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1
Khodaparast, Zahra. "Toxicity of silver nanoparticles and silver nitrate on Nassarius reticulatus larvae." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15327.
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Mestrado em Toxicologia e EcotoxicologiaProduction and utilization of silver nanoparticles (AgNPs) for various applications is growing rapidly, mainly due to their antibacterial activity. Their inclusion in many consumer products led to an increased release of AgNPs in the environment, especially in aquatic ecosystems. AgNPs reach both freshwater and marine environments from the effluents of the wastewater treatment plants, presenting differentiated behavior in these two environments potentially influencing its toxicity. The study of AgNPs toxicity to marine organisms is extremely important to the assessment of the potential risk of AgNPs in the environment. The toxicity of AgNPs on the living organisms is dependent on various environmental conditions. Regarding the toxicity of AgNPs in the marine environment, there is a lack of information on the toxic effects at different salinities. This study upsurges to fill this gap, being the first report on the effects of AgNPs on marine gastropods, using Nassarius reticulatus as a case study. N. reticulatus adults were collected from a reference population in Ria de Aveiro (NW Portugal, 40° 38' 33.24"N | 8° 44' 06.69’’W). Specimens were transported to the laboratory in local seawater and kept in aquaria to spawn. Egg capsules were maintained until veliger larva were noticed, which enclosure was induced by cesarean. These recently hatched larvae were then exposed to nominal concentrations of AgNPs and Ag+ (0.1, 1, 10, 100 μg Ag/L) for up to 96 h, either in the presence or absence of food. Larval mortality and swimming behavior –namely the velum beating arrest–were determined for each treatment. The median lethal concentration (LC50) of AgNPs was higher to that of ionic Ag (AgNO3). Results also revealed that the negative impact of AgNPs on N. reticulatus veligers swimming ability is higher when compared with the effect of ionic Ag (EC50-96 h 1.044 μg Ag/L). However, although the velum arrests have significantly decreased under Ag+ exposure, AgNPs did not show any effects. Additionally, the presence of the food proved to be an effective factor that can cause a significant drop in the mortality of the N. reticulatus larvae exposed to AgNPs.
A produção e utilização de nanopartículas de prata (AgNPs) em diversas aplicações têm crescido rapidamente, principalmente devido à sua atividade antibacteriana. A inclusão de AgNPs em muitos produtos de consumo conduziu a um aumento da sua libertação no meio ambiente, especialmente nos ecossistemas aquáticos. As AgNPs atingem tanto o ambiente marinho como o de água doce a partir da descarga de efluentes de estações de tratamento de águas residuais, apresentando comportamento diferenciado nestes dois meios, potencialmente influenciando a sua toxicidade. O estudo da toxicidade das AgNPs em organismos marinhos é extremamente importante na avaliação do potencial risco da presença de AgNPs no ambiente. A toxicidade de AgNPs emorganismos vivos é dependente de várias condições ambientais. No que se refere à toxicidade das AgNPs em ambiente marinho, verifica-se uma lacuna de informação relativamente aos efeitos tóxicos a diferentes salinidades. Este trabalho surge para preencher esta lacuna, sendo o primeiro relato do efeito de AgNPs em larvas de gastrópodes marinhos, usando Nassarius reticulatus como caso de estudo. Foram colhidos adultos de N. reticulatus de uma população de referência da Ria de Aveiro (NW Portugal, 40° 38' 33.24"N | 8° 44' 06.69’’W). Os espécimes foram transportados para o laboratório em água do local e aí mantidos em aquário até à postura de cápsulas ovígeras. As cápsulas foram mantidas até à observação de larvas velígeras no seu interior, cuja eclosão foi induzida por cesariana. Estas larvas recém-eclodidas foram então expostas a concentrações nominais de AgNPs e Ag+ (0,1, 1, 10, 100 ug de Ag / L), durante 96 h, na presença ou ausência de alimento. A mortalidade larvar e o comportamento de natação, nomeadamente a inibição do batimento do velum, foram determinados para cada um dos tratamentos. A concentração letal média (CL50) das AgNPs revelou-se superior à da Ag iónica (AgNO3). Os resultados também revelaram que o impacto negativo das AgNPs na natação das velígeras de N. reticulatus é superior (EC50-96 h 0.044 μg Ag/L) quando comparado com o efeito da Ag iónica (EC50-96 h 1.044 μg Ag/L). Contudo, embora a inibição da movimentação do velum das larvas ter diminuido significativamente na presença de Ag+, as AgNPs não mostraram quaisquer efeitos na inibição do batimento do velum. Adicionalmente, a presença de alimento revelou ser um fator importante, podendo causar uma redução significativa na mortalidade das larvas de N. reticulatus expostas a AgNPs.
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Yang, Shu. "Electrocatalytic reduction of NOx on metal nanoparticles stabilized by polyoxometalates." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF056.
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L’objet de ce travail est de développer des nouveaux catalyseurs pour réduire les ions nitrites (NO2- /HNO2) et nitrates (NO3-) dans l’eau en étudiant les facteurs qui vont influencer leurs réductions catalytiques. On a montré que la présence de polyoxométallates (POMs) permet d’améliorer les propriétés catalytiques de l’électrode de Cu et d’Ag pour la réduction de ions nitrate et nitrite avec des conditions adaptées. Par la suite, des nanoparticules du cuivre (Cu@POM) ou d’argent (Ag@POM) ont été préparées par électroréduction of CuPOM in situ ou photocatalyse en présence d’ions POMs et Ag(I) respectivement. Leurs propriétés électrocatalytiques ont été étudiées. Six différents polyoxométallates substitués par des atomes de Cu(II) (CuPOMs) ont montré de bonnes activités pour la réduction de nitrite à pH 1 et à pH 5. Deux activités sont observées : au potentiel de la réduction de CuII et au potentiel de réduction des W(VI) du POM. Quant à la réduction du nitrate, [Cu4(H2O)2(P2W15O56)2]16- et [(A-β-SiW9O34)Cu4(OH)3(H2O)(H3N(CH2)3COO)2]3 5- peuvent catalyser la réduction du nitrate à un potentiel au-delà de la réduction du Cu(II) à la réduction des W(VI). Par contre, dans le cas de [(SbW9O33)2{Cu(H2O)}3]12– aucune électrocatalyse n’est observée. Cela indique que le type de POM influence les propriétés catalytiques des nanoparticules. Pour le système Ag@POM photoréduit, un catalyseur hétérogène est préparé et stabilisé par une couche de Nafion. Les nanoparticules Ag@POM sont actives pour la réduction du nitrite et du nitrate et possèdent une activité meilleure que celle mesurée pour l’électrode d’Ag seule. Dans la dernière partie, une étude préliminaire de polyoxométallates encapsulés dans les ‘Metal-Organic Framworks’ (MOFs) e st présentée. L’entité POM conserve ses propriétés électrochimiques et électrocatalytiques pour la réduction de nitrite après immobilisation dans la cage MOFThe object of this work is to develop new catalysts to reduce nitrite ions (NO2- / HNO2) and nitrate ions(NO3-) in water and also tried to understand the factors that will influence catalytic reductions. It has been shown that the presence of polyoxometalates makes it possible to improve the catalytic properties of the Cu and Ag bulk electrodes for the reduction of nitrate and nitrite ions under suitable conditions. Then, the copper or silver nanoparticles decorated with POMs, Cu@POM or Ag@POM), are formed with two different methods: electroreduction in situ of CuPOM or photocatalysis in the presence of POM and Ag(I) ions respectively). Their electrocatalytic properties are presented. Six different Cusubstituted polyoxometalates (CuPOMs) are active for nitrite reduction at pH 1 and pH 5. Two activities are observed at the potential of CuII reduction and at the potential of WVI reduction in POM. [Cu4(H2O)2(P2W15O56)2]16- and [(A-β-SiW9O34)Cu4(OH)3(H2O)(H3N(CH2)3COO)2]3 5- catalyse the nitrate reduction at the potential beyond the reduction of CuII and at the reduction of WVI. On the other hand, no catalysis efficiency was observed with [(SbW9O33)2{Cu(H2O)}3]12-. This indicates the type of POM will influence the catalytic properties of nanoparticles. With the photoreduced Ag@POM nanoparticles, a heterogeneous catalyst is prepared and stabilized by a Nafion layer. Ag@POM nanoparticles are active for the reduction of nitrite and nitrate and have an activity better than the Ag electrode alone. In the last part, a preliminary study of polyoxometalates encapsulated in Metal-Organic Framworks (MOFs) is presented. POM retains its electrochemical and electrocatalytic properties toward the reduction of nitrite after immobilized in the cage of MOF
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Domingues, Vasco Filipe de Castro. "Toxicity of silver nanoparticles and silver nitrate to the freshwater planarian Dugesia tigrina." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17016.
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Mestrado em Toxicologia e EcotoxicologiaAtualmente, as nanopartículas de prata (AgNP) são bastante utilizadas em vários produtos devido às suas propriedades únicas e excecionais, nomeadamente a sua potente atividade antibacteriana. Algumas das suas aplicações comuns são em têxteis, produtos cosméticos e tintas. Deste modo, é esperada a presença de AgNP nos sistemas aquáticos. Tendo isto em consideração, o objetivo deste trabalho é descrever os efeitos tóxicos de AgNP de diferentes tamanhos, e comparar estes efeitos com os induzidos pela exposição a AgNO3 usando as características comportamentais das planárias da espécie Dugesia tigrina. Foram efetuados testes de exposição aguda (96 h) e testes de exposição crónica (8 dias) onde foram avaliados parâmetros como a sobrevivência, a locomoção, alimentação e regeneração cefálica. Foram selecionadas AgNP de diferentes tamanhos (AgNP de 10-25 nm e AgNP 3-8 nm) e comparados os efeitos com os da exposição a AgNO3, de modo a analisar se a toxicidade tem origem na libertação de iões Ag ou se é devida às propriedades das diferentes nanopartículas. Os resultados mostraram que os valores de LC50 para as 24, 48, 72 e 96 h não variaram ao longo do tempo para AgNP (10-25 nm) (76.62 μg L-1) e para AgNO3 (109.1 μg L-1). As planárias experienciaram nas primeiras 24 h várias alterações morfológicas na zona da cabeça como aurículas suprimidas e principalmente dissolução da cabeça. Estes efeitos notaram-se principalmente na AgNP (10-25 nm) e AgNO3. Em relação à exposição crónica, as planárias apresentaram uma redução significativa na locomoção e na alimentação na exposição a todas as nanopartículas estudadas, sendo estes parâmetros os mais sensíveis para D. tigrina. Relativamente à capacidade de regeneração não houve efeitos significativos à exposição a Ag. A fonte de toxicidade pode estar relacionada com as propriedades das AgNP que interferem com o sistema nervoso das planárias, causando a sua morte. Este estudo demonstrou que as planárias são um organismo adequado para estudos ecotoxicológicos comportamentais e devem ser considerados em metodologias de avaliação de risco ambiental.
Currently, silver nanoparticles (AgNP) are widely used in several products because of their unique and exceptional properties, particularly its potent antibacterial activity. Thus, AgNP are very often applied in textiles, cosmetics and paints. Under those circumstances, AgNP is expected to be present in aquatic systems. Taking this into consideration, the objective of the present work is to describe the toxicity of AgNP of different sizes and compare to the toxicity from AgNO3 exposure using behavioral endpoints of the planarian Dugesia tigrina. Acute exposure tests (96 h) and chronic exposure tests (8 days) were performed, in which parameters such as survival, locomotion, feeding and regeneration were evaluated. Therefore, AgNP of different sizes were selected (AgNP of 10-25 nm and AgNP 3-8 nm) and effects from exposure were compared to those from AgNO3, in order to analyze whether the source of toxicity was originated by release the ionic form of Ag or related to the inherent properties of nanoparticles. The results showed that LC50 values at 24, 48, 72 and 96 h were equal over time for AgNP (10-25 nm) (76.62 μg L-1) and for AgNO3 (109.1 μg L -1). In the first 24 h, planarians experienced several morphological alterations at the head region such as suppressed auricles and mainly head dissolution. These effects were noted mainly in AgNP (10-25 nm) and AgNO3 exposures. Regarding chronic exposure, planarians presented a significant reduction in locomotion and feeding activity upon both AgNP exposures. These endpoints revealed to be the most sensitive to D. tigrina. There were no significant effects on the regeneration test. The source of toxicity may be related to the properties of AgNP that interfere with nervous system of planarians consequently causing their death. This study demonstrated that planarians are an adequate organism for behavioural ecotoxicological studies and should be considered in environmental risk assessment methodologies.
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Babaahmadi, V., M. Ghanbarajjeh, T. Toliyat, and M. Montazer. "Photochemical reduction of silver nitrate to nano silver using stannous chloride, ctab and daylight irradiation." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20633.
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Silver nanoparticles (NPs) were synthesized and stabilized by a simple method in
aqueous solution, by the reduction of silver nitrate with stannous chloride (SnCl2.2H2O)
and cetyl trimethyl ammonium bromide (CTAB)through day light irradiation. Thereby,
the silver nanoparticles were colloidally stabilized by CTAB as a surfactant. The synthesis
of silver NPs with different size were possible by changing the reaction conditions
such as reagent ratio. The silver NPs were characterized by Dynamic Light Scattering
(DLS) and UV-visible spectroscopy. A very strong plasmon resonance peak at 400-500
nm in the UV-visible spectra is a clear consequence of the silver NPs production. The
synthesized silver NPs showed good stability by using CTAB.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20633
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Fridley, Brooke A. "Phytoformations of silver and gold nanoparticles." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4957.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xiii, 104 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 70-73).
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Luke, Nicholas L. "A comparison of the antimicrobial efficacy of silver diamine fluoride and silver nitrate: an in vitro study." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5294.
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A COMPARISON OF THE ANTIMICROBIAL EFFICACY OF SILVER DIAMINE FLUORIDE AND SILVER NITRATE: AN IN VITRO STUDY
By: Nicholas L Luke, D.D.S.
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry at Virginia Commonwealth University.
Virginia Commonwealth University, May 2018
Thesis Advisor: William O. Dahlke Jr., D.M.D.
Pediatric Dentistry, Department Chair
Purpose: To determine the antimicrobial efficacy of SDF and SN/NaF.
Methods: Three bacterial species were combined to create an in vitro biofilm. Treatment was completed with SN, SN/NaF, SDF, SDF½ or untreated (control).
Results: The untreated group demonstrated significantly higher growth than all other treatment groups across the study. On the BHI-plates (1-day), there were significant differences between all treatments except SDF and SDF½. On the BHI-plates (3-days), SN/NaF was not significantly different from SDF or SDF½. On the L-MRS-plates (1-day), both SN treatment groups yielded significantly higher growth than the SDF groups. On the L-MRS-plates (3-days), SN yielded significantly higher growth than SN/NaF, SDF, and SDF½.
Conclusion: SDF is more effective than SN/NaF, with the exception of BHI-plates (3-days) only and SN/NaF is more effective than SN on primarily S. mutans and L. acidophilus. There is evidence of a possible antimicrobial tolerance of oral bacteria to silver.
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AlNajjar, Reham M. "A comparison of the antimicrobial efficacy of silver diamine fluoride and silver nitrate: an ex vivo study." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5800.
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A comparison of the antimicrobial efficacy of silver diamine fluoride and silver nitrate on various cariogenic bacteria: an ex vivo study By: Reham AlNajjar, D.D.S.
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry at Virginia Commonwealth University. Virginia Commonwealth University, 2019
Thesis Advisor: William Dahlke, D.M.D., Associate Professor and Chair of Pediatric Dentistry, School of Dentistry
Purpose: The use of silver-based antimicrobials is an emerging method for the treatment of dental caries. In this study, the authors compare the efficacy of the two most prominent silver- based therapeutics, silver diamine fluoride (SDF) and silver nitrate (AgNO3), on cariogenic and non-cariogenic multispecies biofilms. Currently there is a lack of studies comparing the efficacy of SDF to AgNO3.
Methods: Plaque samples from anterior and posterior tooth sites from children presenting both with early childhood caries and caries-free children were collected, pooled, and utilized to create four ex vivo biofilm systems in artificial saliva. SDF and AgNO3 were administered to these biofilms and bacterial survival was quantified and compared to untreated controls.
Results: Each of the four pooled sample types was applied to plates coated in artificial saliva + 1% sucrose. Both SDF and AgNO3 were very effective against plaque derived biofilms when compared to untreated biofilms (P0.05) in the potency of each compound.
Conclusions: SDF and AgNO3 significantly inhibit ex vivo cariogenic and non-cariogenic biofilms at similar levels.
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Salvio, Luciana Andrea. "Resistencia da união e qualidade de camada hibrida segundo a forma de interação dos sistemas adesivos a dentina." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288192.
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Orientador: Mario Fernando de GoesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-06T08:38:04Z (GMT). No. of bitstreams: 1 Salvio_LucianaAndrea_D.pdf: 9815435 bytes, checksum: 9c80659f327995fb1aab0fb6244ecb67 (MD5) Previous issue date: 2006
Resumo: O objetivo foi avaliar a resistência da união e qualidade de camada híbrida de acordo com o modo de interação de diferentes sistemas adesivos com a dentina. Para a avaliação da resistência da união à tração foram utilizados sete terceiros molares humanos hígidos, os quais foram submetidos cortes perpendiculares ao longo eixo do dente para obtenção de superfícies planas de dentina média. Estas foram secionadas em quatro partes iguais, por dois cortes perpendiculares entre si. Os sistemas de ¿passo único¿ Adper Prompt (ADP) e Xeno III (XE); de ¿dois passos¿ Clearfil SE Bond (SE) e Adhe SE (ADSE); e o Single Bond (SB) foram aplicados sobre as superfícies dentinárias seguindo as instruções dos fabricantes. Sobre a dentina tratada foi construído um bloco de resina composta (Filtek Z250, 3M/ESPE) com 5 mm de altura. Após 24 h, cada espécime foi secionado de modo a obter espécimes com formato de ¿palito¿ com área média de 1mm2 para a realização do teste de tração. Os padrões de fratura foram examinados em microscopia eletrônica de varredura (MEV). Os valores foram submetidos à análise da variância e ao teste Tukey (p<0,05). Para a avaliação da qualidade de camada híbrida foram utilizados 15 terceiros molares, dos quais, através de cortes perpendiculares ao longo eixo, foram obtidas duas superfícies planas e adjacentes de dentina média por dente. Sobre estas duas superfícies adjacentes, foi aplicado o mesmo sistema adesivo. A seguir, entre as superfícies hibridizadas foi aplicada uma resina de baixa viscosidade de modo a uni-las formando um bloco composto por dentina-resina-dentina após a polimerização. Decorridas 24h cada bloco foi cortado no sentido mésio-distal criando 12 interfaces por adesivo; 4 interfaces foram submetidas à técnica de pigmentação com nitrato de prata amoniacal; 4 à técnica de pigmentação com metenamina de prata; e 2 serviram de controle. Todas as interfaces foram observadas sob MEV. As médias de resistência de união, em MPa, foram: SE (51,48 ± 15,24); ADSE (37,08 ± 12,55); XE (36,24 ± 11,95); SB (26,20 ± 4,39) e ADP (24,92 ± 6,17). Houve predominância de fraturas do tipo mista entre adesivo e camada híbrida para SB, ADSE e XE; e fratura coesiva na camada de adesivo para SE e ADP. Em relação à qualidade de camada híbrida, SB mostrou maior intensidade na deposição de grãos de prata metálica na camada híbrida quando comparado aos outros sistemas. SE e ADSE apresentaram deposições de grãos de prata metálica semelhantes entre si e em menor intensidade comparada com os demais grupos. XE e ADP mostraram quantias moderadas de grãos prata metálica na camada híbrida e, diferentemente dos demais, dentro da camada de adesivo. Áreas de nanoinfiltração no interior da interface de união puderam ser identificadas tanto pela solução de nitrato de prata amoniacal como também pela solução de metenamina de prata. De acordo com o modo de interação dos sistemas adesivos com a dentina há formação de diferentes padrões de camada híbrida que, provavelmente, infuenciou nos valores de resistência de união
Abstract: This study evaluated the bond strength and hybrid layer formation between different adhesive systems and dentine. To evaluate the bond strength, seven molars fresh extracted were sectioned in multiple parallel layers. The middle dentine layers were selected and sectioned into four equal pieces perpendicular to the previous sections. The ¿one step¿ self-etching adhesive systems Adper Prompt (ADP) and XENO III (XE); the ¿two steps¿ self-etching adhesive systems Clearfil SE Bond (SE) and Adhe SE (ADSE) and the ¿total-etch¿ adhesive Single Bond (SB) were applied on dentine surfaces according to the manufactures¿ instructions. A block of resin (Filtek Z250, 3M/ESPE) of 5 mm height was built in three increments, each one light cured for 20 seconds, on the treated dentine. The specimens were stored in 37°C distilled water for 24h and then sectioned in X and Y directions to obtain 1 mm2 area sticks. The sticks were submitted to a microtensile bond strength test in a universal testing machine (Instron 4411) at a crosshead speed of 0.5mm/min. The results were submitted to one-way analysis of variance and Tukey¿s test at a 5% level of significance. To evaluate the hybrid layer, 15 third molars were used. Two adjacent flat surfaces of middle dentine were obtained for each tooth. The same adhesive system was applied on these two adjacent surfaces, which were applied according to manufacturers' instructions. A resin ¿sandwich¿ block of dentine/resin/dentine was made filling the two adjacent slices with a low viscosity resin, which was polymerized for 20s. After 24 h, each block was mesio-distally sectioned producing 12 interfaces per adhesive. Four interfaces were stained with ammoniacal silver nitrate solution and 4 with silver methenamine solution. The other four were kept without stain and used as a control group. All the interfaces were observed under SEM. The bond strength means, in MPa, were: SE (51.48 ± 15.24); ADSE (37.08 ± 12.55); XE (36.24 ± 11.95); SB (26.20 ± 4.39) and ADP (24.92 ± 6.17). There was prevalence of mixed failure between adhesive and hybrid layer for SB, ADSE and XE; and prevalence of cohesive failure in the adhesive layer for SE and ADP. According to the hybrid layer, SB showed a greater intensity of silver grains deposition than the other systems. SE and ADSE presented similar silver grains depositions but in a small quantity. XE and ADP differing from the others, not only showed moderate amounts of silver grains in the hybrid layer, but also inside the adhesive layer. It was possible to identify nanoleakage inside the bond interface with both used stains. According to the interactions of the adhesive systems with dentine, there were different hybrid layer patterns, which may influence the bond strength
Doutorado
Materiais Dentarios
Doutor em Materiais Dentários
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Costa, José Ferreira. ""Soluções aquosas de nitrato de prata: características e desempenho nos testes de infiltração"." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/23/23140/tde-12012006-101151/.
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Soluções de nitrato de prata são freqüentemente usadas em testes de micro e nanoinfiltração, apesar de nem todas as suas características estarem definidas claramente na literatura. Neste estudo foram avaliadas soluções aquosas de nitrato de prata quanto ao pH e à quantidade de prata iônica (ppm) em várias concentrações, bem como o desempenho dessas soluções em testes de microinfiltração realizados em dentes decíduos e permanentes. Numa primeira fase foi analisado o pH (pHmetro digital) de solução a 50% (p/v), tendo como variáveis a pureza da água, a marca comercial do sal, a cor do frasco, e a idade pós-preparo. Posteriormente, avaliou-se a quantidade de prata iônica, por espectrometria de emissão atômica, presente nas soluções (1%, 5%, 25% e 50%) ao longo de 168 horas de armazenagem. Em cavidades de classe V, confeccionadas nas faces vestibular e lingual/palatina de molares, foram aplicados dois sistemas adesivos (OptiBond FL ou OptiBond Solo Plus SE). Após a restauração (Filtek Z-250) foi determinado o valor médio de microinfiltração (mm) para diversas concentrações e idade pós-preparo das soluções. Os dados obtidos foram tratados por análise de variância e teste de Tukey (a=0,05). As soluções analisadas na primeira etapa apresentaram pH médio entre 7,9±2,2 a 11,8±0,9, e houve diferenças significativas para todas as variáveis. O teor médio de prata iônica apresentou diferenças significativas para o fator Concentração (4,75±0,5 a 1% e 293±15,3ppm a 50%); porém, não houve diferença para o fator Idade. Nos testes de microinfiltração houve diferença significante apenas para o fator Adesivo (p<0,01); os demais fatores e as interações não apresentaram diferenças significativas. Com base nos resultados obtidos neste estudo pode-se concluir que: 1) o pH de soluções aquosas de nitrato de prata varia de neutro a alcalino; 2) a quantidade de prata iônica e o pH se mantêm estáveis por até 168h; 3) a concentração e a idade pós-preparo das soluções não interferiram nos valores médios de microinfiltração; 4) o sistema adesivo OptiBond FL apresentou menores valores de microinfiltração, em dentes permanentes e decíduosSilver nitrate solutions are frequently used in micro and nanoleakage tests, although not all of their characteristics are clearly defined in the literature. In this study an assessment was made of aqueous silver nitrate solutions as regards pH and the amount of ionic silver (ppm) in various concentrations, as well as the performance of these solutions in microleakage tests performed in primary and permanent teeth. In the first phase the pH (digital pH meter) of a 50% (w/v) solution was analyzed, having water purity, commercial brand of the salt, the color of the flask, and the storage time as variables. Afterwards, the amount of ionic silver present in the solutions (1%, 5%, 25% and 50%) was evaluated by atomic emission spectrometry, throughout 168 hours of storage. In Class V cavities made on the vestibular and lingual/palatal faces of molars, two adhesive systems were applied (OptiBond FL or OptiBond Solo Plus SE). After restoration (Filtek Z-250) the mean microleakage value (mm) was determined for the various concentrations and post-preparation time of the solutions. The data obtained were submitted to analysis of variance and the Tukey test (a=0.05). The solutions analyzed in the first stage had a mean pH ranging between 7.9±2.2 and 11.8±0.9, and there were significant differences for all the variables. The mean ionic silver content presented with significant differences for the factor Concentration (4.75±0.5 at 1% and 293±15.3 ppm at 50%); but there was no difference for the factor Time. In the microleakage tests there was significant difference only for the factor Adhesive (p<0.01); the other factors and the interactions did not present with any significant differences. Based on the results obtained in this study, it may be concluded that: 1) the pH of aqueous silver nitrate solutions varies from neutral to alkaline; 2) the amount of ionic silver and pH remained stable for up to 168h; 3) the concentration and the post-preparation time of the solutions did not interfere with the mean microleakage values; 4) the adhesive system OptiBond FL presented with the lowest microleakage values in both permanent and primary teeth
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Mello, Lucas Braga de [UNESP]. "Preparação e caracterização de filmes híbridos de (AgNO3)." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144366.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O processo Sol-Gel tem permido preparar materiais vítreos ou vítro-cerâmicos com novas composições com alto grau de pureza, homogêneos, materiais híbridos orgânicos e inorgânicos (OIHM) e até materiais impossíveis de serem preparados por processos convencionais. Um dos melhores sistemas para obtenção dos OIHM de sílica (ORMOSIL – Silicato Organicamente Modificado) é a reação combinada com alcoóxidos de Silício como o TEOS (Tetraetilortosilicato) e alcoóxidos funcionalizados como o GPTS (3-Glicidoxipropil-trimetoxisilano). A Prata, é aplicada em diversas áreas como por exemplo, em pinturas a base de Prata (utilizados para circuitos impressos), em filmes fotográficos, películas de vidros dentre várias outras aplicações. Dois efeitos encontrados quando uma amostra GTD-Ag (Amostra com a dopagem de AgNO3), irradiada por uma lâmpada UV e tratada a temperatura (acima de 80 °C), são os efeitos fotocrômicos e termocrômicos. Para o efeito fotocrômico, a irradiação por lâmpada UV, produz partículas de prata oxidadas (Ag+) que transformam-se em partículas de prata reduzidas (Ago), ocorrendo-se assim, o escurecimento dos filmes (redução). O clareamento das amostras GTD-Ag (oxidação), foi obtido através de um agente oxidante, o H2O2. Para observar o efeito termocrômico, as amostras GTD-Ag, são tratadas em forno convencional em temperaturas de 80 °C à 550 °C em atmosferas de N2 e ambiente. No tratamento térmico em atmosfera de N2, foi possível observar o escurecimento (redução) da amostra, a partir da temperatura de 80 °C, e em tratamento térmico à atmosfera ambiente, observamos um clareamento da amostra (oxidação), a partir da temperatura de 200 °C. Utilizando a técnica de análise térmica diferencial (DTA), foi possível verificar a óxido-redução da amostra GTD-Ag, quando tratada em atmosfera ambiente, em temperaturas superiores a 150 °C. Comportamento semelhante é observado para as amostras GTD (Amostra sem dopagem de AgNO3), em temperaturas acima de 200 °C, ocorrendo um efeito conhecido por pirólise, que no nosso caso é a degradação do grupo epóxi.
The sol-gel process has allowed prepare vitreous or vitro-ceramic materials with novel compositions with high purity, homogeneous, organic and inorganic hybrid materials (OIHM) and impossible materials to be prepared by conventional methods. One of the better systems for obtaining OIHM silica (ORMOSIL - Silicate Organically Modified), is the combined reaction of silicon alkoxides such as TEOS (Tetraethylorthosilicate), and functionalised alkoxides such as GPTS (3- Glycidoxypropyl-trimethoxysilane). The Silver is applied in various areas such as Silver paintings (used for printed circuits) on photographic films, glass films among many other applications. Two effects found when a GTD-Ag sample (Sample with AgNO3 doping) irradiated by a UV lamp and treated at temperatures (above 80 °C), are photochromic and thermochromic effects. For the photochromic effect, the UV irradiation lamp produces oxidized silver particles (Ag+) which becomes reduced particles silver (Agº), occurring to thereby darkening of the films (reduction). The samples of the bleaching GTD-Ag (oxidation) were obtained by an oxidizing agent H2O2. To observe the thermochromic effect, the GTD-Ag samples are treated in a conventional oven at temperatures of 80 °C to 550 °C in N2 atmosphere and ambient. In the heat treatment in N 2 atmosphere, was observed to darkening (reduction) of the sample from the 80 °C temperature and treatments to the ambient atmosphere, we observed a whitening of the sample (oxidation) at low temperature 200 °C. Using the differential thermal analysis (DTA), we found the redox sample GTD-Ag, when treated in atmosphere ambient at temperatures above 150 °C. Similar behavior is observed for the GTD samples (Sample undoped AgNO3) at temperatures above 200 °C, occurring an effect known by pyrolysis which in our case is the degradation of the epoxy group.
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Peixoto, Sara Cristiana Lopes. "Changes of the microbial communities as a mean to evaluate the impact of soil contamination by nanoparticles." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16452.
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Mestrado em MicrobiologiaSilver nanoparticles (AgNPs) are broadly used in the industry due to AgNPs’ antibacterial proprieties. Uncontrolled released of AgNPs and persistence in the environment might enhance the concern of soil contamination by AgNPs. Thus, the aim of this thesis was to evaluate the effects of AgNPs on the bacterial communities using two complementary approaches: a culture-independent method [Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE)] and a culture-dependent method (disc diffusion to analyze the bacterial susceptibility). To explore this aim, the bacterial communities of the LUFA 2.2 soil was exposed to 5 µg/kg of AgNPs or silver cation (Ag+, provided as AgNO3) during 56 days. The analysis of the soil bacterial communities by PCR-DGGE included those retrieved from soil at 42 and 56 days as well as those developed in the presence and absence of Porcellionides pruinosus. For the susceptibility tests, only the soil bacterial communities retrieved from soil at 56 days were analyzed. The first method enabled to investigate the effects of AgNPs or Ag+ on the bacterial community of soil and to understand if these effects changed with the presence of P. pruinosus or along the exposure period. The second methodology provided an analysis of the viable soil bacterial community and allowed to assess the susceptibility responses of the soil bacterial communities according to the silver form (AgNPs or Ag+), silver amounts (10 µg, 1 µg or 0.1 µg), joint exposure to AgNPs and Ag+ and after previous exposure to silver. By using PCR-DGGE, we demonstrated that the silver forms (AgNPs and Ag+), exposure period (42 or 56 days) and the presence of P. pruinosus were relevant to alter the structure of soil bacterial community. P. pruinosus showed to be probably useful to minimize the effects of silver cation for exposures close to 2 months; yet, even in the presence of this isopod, the AgNPs might still be a risk for the soil bacterial communities. By using disc diffusion method we provided an analysis of the viable soil bacterial community demonstrating that the silver form, the amount and the combination of both silver forms affected the susceptibility of the soil bacterial communities. Bacteria were more susceptible to Ag+ than to AgNPs and amount-dependent as well as addition effects were demonstrated. Although the bacterial communities being analyzed by the two methods were different, overall patterns were identified: bacteria are affected by both silver forms, particularly by showing altered community structure and showing susceptibility through growth inhibition. Yet, lower concentrations than those herein tested are imperative to be considered in future investigations as we obtained most of the susceptibility changes for exposures with lower amounts (1 and 0.1 µg). Compared to silver cation, the AgNPs appears to affect less the soil bacterial communities. Thus, this thesis strengthens how valuable is to use these communities to evaluate the effects of the soil contamination as they proved to be sensible to silver contamination by both methodologies.
As nanopartículas de prata (AgNPs) são muito utilizadas na indústria devido às suas propriedades antibacterianas. A libertação de forma não controlada das AgNPs para o ambiente e a sua persistência no mesmo, aumentam a preocupação em relação à contaminação dos solos por AgNPs. Assim, o objetivo desta tese foi analisar os efeitos das AgNPs nas comunidades bacterianas do solo recorrendo a duas abordagens complementares: uma independente do cultivo [Polymerase Chain Reaction- Denaturing Gradient Gel Electrophoresis (PCR-DGGE)] e outra dependente do cultivo (método de difusão por discos para analisar a suscetibilidade bacteriana). Para dar cumprimento a este objectivo, as comunidades bacterianas do solo LUFA 2.2 foram expostas a 5 µg/kg de AgNPs ou de catião prata (Ag+, disponibilizado como AgNO3) durante 56 dias. A análise das comunidades bacterianas do solo por PCR-DGGE foi feita para 42 e 56 dias e na presença e ausência do Porcellionides pruinosus. Para os testes de suscetibilidade, apenas as comunidades bacterianas do solo para 56 dias foram analisadas. O primeiro método possibilitou investigar os efeitos das AgNPs ou Ag+ nas comunidades bacterianas do solo e compreender se estes efeitos alteravam com a presença do P. pruinosus ou ao longo do tempo de exposição. O segundo método permitiu avaliar a resposta de suscetibilidade das comunidades bacterianas do solo atendendo à forma (AgNPs ou Ag+) e quantidade (10 µg, 1 µg ou 0.1 µg) da prata, à exposição conjunta e após reincidência da contaminação por prata. Com o PCR-DGGE demostrou-se que a forma da prata (AgNPs ou Ag+), o período de exposição (42 ou 56 dias) e a presença do P. pruinosus foram relevantes para a alteração da comunidade bacteriana do solo. O P. pruinosus poderá ser, provavelmente, útil para a bioremediação de catião prata para exposições perto dos 2 meses; ainda assim, mesmo na presença deste isópode, as AgNPs poderão constituir um risco para as comunidades bacterianas do solo. Através do método de difusão por discos foi possível disponibilizar uma análise da fracção viável das comunidades bacterianas do solo demonstrando que a forma, quantidade e combinação de ambas as formas de prata afectaram a suscetibilidade das comunidades bacterianas do solo. As bactérias mostraram ser mais suscetíveis Ag+ do que às AgNPs sendo também possível observar uma resposta dependente da quantidade além do efeito aditivo para a exposição combinada. Apesar dos efeitos das nanopartículas de prata nas comunidades bacterianas terem sido analisadas por dois métodos, foram identificados alguns padrões: as bactérias foram afetadas por ambas as formas de prata, mostrando que quer a estrutura da comunidade quer a suscetibilidade eram alteradas. É imperativa a análise de baixas quantidades em investigações futuras, além das testadas nesta tese, já que a resposta de suscetibilidade alterou-se para exposição prévia a contaminações com quantidades baixas (1 e 0.1 µg). Comparativamente com o catião de prata, as AgNPs parecem afetar menos as comunidades bacterianas do solo. Assim, esta tese reforça o quão valioso é usar estas comunidades para avaliar os efeitos da contaminação no solo, já que provaram ser sensíveis à contaminação de prata pelas duas metodologias.
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Araújo, Cíntia Tereza Pimenta de 1968. "Influencia da distancia da ativação dos sistemas adesivos autocondicionantes na resistencia de união e qualidade da hibridização em dentina e esmalte." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289632.
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Orientador: Luis Alexandre Maffei Sartini PaulilloDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Os sistemas adesivos autocondicionantes apresentam alta concentração de água utilizada como solvente para ionização de monômeros ácidos. A presença do excesso deste solvente no adesivo aplicado ao tecido dental pode comprometer a formação da camada híbrida, como também interferir na polimerização dos monômeros, produzindo interfaces de união permeáveis. O uso de sistemas adesivos autocondicionantes em situações clínicas de preparos cavitários Classe II com caixas proximais profundas, apresenta além dos problemas relacionados à sua composição, a possibilidade de ter a qualidade de polimerização afetada pela distância da fonte de luz nas paredes mais profundas. Assim a proposta deste estudo foi avaliar a influência da distância da fonte de luz na resistência à união através da microtração e avaliar a qualidade de hibridização através da nanoinfiltração de nitrato de prata em sistemas adesivos autocondicionantes aplicados aos substratos de esmalte e dentina. Para a realização deste estudo foram utilizados 198 incisivos bovinos e três sistemas adesivos autocondicionantes, Clearfil Protect Bond, Clearfil Tri-S e One up Bond F Plus que foram aplicados em superfícies planas de esmalte e dentina. A fotoativação dos adesivos foi realizada nas distâncias de 0,5, 3 e 6 mm e após a polimerização dos adesivos foi confeccionado um bloco de resina composta TPH3 de 4 mm de altura. Os resultados de microtração mostraram que distância da fonte de luz não influenciou significativamente a resistência à união, entretanto a mesma foi dependente do sistema adesivo e do substrato, em que o adesivo de dois passos Clearfil Protect Bond-Kuraray apresentou melhor comportamento em todas as condições experimentais. Entre os substratos, o esmalte mostrou as maiores médias de resistência de união. A análise de variância revelou diferenças significativas de porcentagem de nanoinfiltração para os fatores em estudo sistema adesivo (p<0.0001), substrato dental (p=0,0001) e para as interações distânciaXsubstrato (P=0,0159) e adesivoXsubstrato (P=0,0079). Para a interação distânciaXsubstrato, não foram observadas diferenças significativas de nanoinfiltração entre os grupos fotoativados às distâncias de 3 e 6 mm nas interfaces em dentina, entretanto os mesmos apresentaram menor nanoinfiltração do que os grupos com 0,5 mm de distância de fotoativação. Assim pelos dados observados neste estudo pôde-se concluir que a distância da fonte de luz não influenciou a resistência à microtração dos sistemas adesivos e o padrão de nanoinfiltração das interfaces em esmalte. Por outro lado, o padrão de nanoinfiltração em dentina foi adversamente influenciada pela fotoativação às distâncias de 0,5 e 6 mm.
Abstract: The self-etching adhesives systems present high water content that are used as solvent for acid monomer ionization. The presence of the excess of this solvent in the hybrid layer can compromise its the formation, as well as to affect the polymerization of monomers producing bonding interfaces permeables. The use of self-etching adhesives in clinical situations of Class II cavities with deep box, presents beyond the problems related to its composition, the possibility to have the quality of polymerization affected for the distance of the source of light in the deepest walls. Thus the purpose of this study was to evaluate the influence of the light-tip distance of a halogen light-curing lights in the microtensile bond strength (MTBS) and to evaluate the quality of hybridization through the nanoleakage of self-etch adhesive systems applied to substrate of enamel and dentine. For the accomplishment of this study 198 bovine incisors and three selfetching adhesive systems were used, Clearfil Protect Bond, Clearfil Tri-S and One up Bond F Plus that were applied in plain surfaces of enamel and dentine. The photoactivation of the adhesives was carried through at 0,5, 3 and 6 mm distances and after a 4-mm thick TPH3 composite block was built. The results showed that distance of the light-guide did not influence significantly the MTS, however the same one were dependent of the adhesive system and substrate, where the adhesive of two steps Clearfil Protect Bond (Kuraray) presented better behavior in all experimental conditions. Between dentals substrate the enamel showed highest mean bond strength. For the nanoleakage analysis, the threeway ANOVA detected no significant difference for the distance of the lightcuring tip and significant differences for the adhesive (p<0.0001) and substrate (p<0.0001) factors, and the double interactions between distance X substrate (p=0.0159) and between adhesive X substrate (p = 0.0079) were also significant. For the interaction distance X substrate, no significant difference in nanoleakage was observed among groups light-activated with curing unit tip having a distance of 3 and 6 mm when the adhesive interfaces were in dentin. On the other hand, such groups showed lower nanoleakage than those with 0,5 mm distance between curing unit tip and the bonded surface. Thus for the data observed in this study it could be concluded that the distance of the light-guide did not influence the !TBS values of the adhesives systems and the nanoleakage patterns of the enamel interfaces. However, the nanoleakage patterns were adversely influenced by photoactivation at distances of 0,5 and 6 mm.
Mestrado
Dentística
Mestre em Clínica Odontológica
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Maaza, Malik. "Latent and thermal energy storage enhancement of silver nanowires-nitrate molten salt for concentrated solar power." University of Western Cape, 2020. http://hdl.handle.net/11394/8038.
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>Magister Scientiae - MScPhase change material (PCM) through latent heat of molten salt, is a convincing way for thermal energy storage in CSP applications due to its high volume density. Molten salt, with (60% NaNO3 and 40% KNO3) has been used extensively for energy storage however; the low thermal conductivity and specific heat have limited its large implementation in solar applications. For that, molten salt with the additive of silver nanowires (AgNWs) was synthesized and characterized. This research project aims to investigate the thermophysical properties enhancement of nanosalt (Mixture of molten salt and silver nanowires). The results obtained showed that by simply adjusting the temperature, Silver nanowires with high aspect ratio have been synthesized through the enhanced PVP polyol process method. SEM results revealed a network of silver nanowires and TEM results confirmed the presence of silver nanowires with an average diameter of 129 nm and 16 μm in length.
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Miller, Christopher J. "An Additive Printing Process for Conductive Structures Based on Low Pressure Argon Plasma Treatment of Silver Nitrate-based Inks." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1497046125099719.
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Sánchez-ayala, Alfonso. "AVALIAÇÃO DA INFLUÊNCIA DA CICLAGEM TÉRMICA E MECÂNICA NA EFETIVIDADE DA INTERFACE ADESIVA." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2008. http://tede2.uepg.br/jspui/handle/prefix/1695.
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Previous issue date: 2008-01-31The aim of this study was to evaluate in vitro the adhesive effectiveness in class V cavities using four different adhesive systems, being submit to thermocycling and occlusal load cycling. The cavities had a dimension of 3x2x1.8 mm3 and were made on amelo-cement junction on buccal and lingual of 80 human premolars (n=160). The used adhesive systems were Adper Single Bond 2, AdheSE, Adper Prompt LPop and One Coat 7.0. The used composite was Synergy® D6. The adhesive and photopolymerization (600 mW/cm2) proceedings were made conventionally and following the manufacturer recommendations. The specimens were divided in 4 groups (n=40) according to adhesive system used. Each group was divided in 4 subgroups (n=10) according to applycated stress (thermocycling, occlusal load cycling and thermocycling+occlusal load cycling). Each subgroup included 1 control group without stressing. The thermocycling was made using 500 cycles, with 5-55 C, dwell time of 15 seg and transfer time of 5 seg. The occlusal load cycling was made applying a force of 40-70 N during 50000 cycles with 2 Hz of frequency. Later, the specimens were impermeabilited and immersed in tracer agent of 50 % silver nitrate solution by 2 hours. Finally, the specimens were prepared for adhesive effectiveness evaluation through optic microscopy 40X (marginal microleakage occurrence) and scanning electronic microscopy 1000X (gaps formation). The tracer agent microleakage was measured qualitative (score) and quantitatively . The gap width was measured on 3 points of center of axial wall. The Kruskal-Wallis and post-hoc de Dunn, and ANOVA two-way and post-hoc Bonferroni tests were used on statistic analysis. Despite of few differences found in used adhesive system performance, the tendency could be observed to the increase of the marginal microleakage in the submitted groups specifically to thermocycling. On the other hand, the axial gaps formation presented progressively higher width in the submitted groups to thermocycling, occlusal load cycling and thermocycling+occlusal load cycling. It was concluded that the used adhesive system presented similar adhesive effectiveness when were submitted to thermal and mechanical stress.
A proposição deste estudo foi avaliar in vitro a efetividade adesiva em cavidades de classe V utilizando quatro diferentes sistemas adesivos, sendo submetidas a termociclagem e carga cíclica oclusal. As cavidades tiveram uma dimensão de 3x2x1.8 mm3 e foram realizadas na união amelo-cementária em vestibular e lingual de 80 pré-molares humanos (n=160). Os sistemas adesivos empregados foram Adper Single Bond 2, AdheSE, Adper Prompt L-Pop e One Coat 7.0. A resina composta utilizada foi Synergy D6. Os procedimentos de adesão e fotopolomerização (600 mW/cm2) foram realizados convencionalmente e seguindo as recomendações do fabricante. Os espécimes foram divididos em 4 grupos (n=40) segundo o tipo sistema adesivo utilizado. Cada grupo foi dividido em 4 subgrupos (n=10) segundo o tipo de estresse aplicado (termociclagem, carga cíclica oclusal e termociclagem+carga cíclica oclusal). Cada subgrupo incluiu 1 grupo controle sem estresse. A termociclagem foi realizada utilizando 500 ciclos a 5-55 C, 15 seg de tempo de permanência em cada temperatura e 5 seg de tempo de transferência. A carga cíclica oclusal foi realizada aplicando uma força de 40-70 N durante 50000 ciclos com freqüência de 2 Hz. Posteriormente, os espécimes foram impermeabilizados e imersos em agente traçador de solução a 50 de nitrato de prata por 2 horas. Finalmente, os espécimes foram preparados para a avaliação da efetividade adesiva por meio de microscopia óptica 40X (ocorrência de microinfiltração marginal) e microscopia eletrônica de varredura 1000x (formação de fendas). A microinfiltração do agente traçador foi mensurada qualitativa (escore) e quantitativamente . A largura das fendas foi medida (μm) em 3 pontos do centro da parede axial. Os testes de Kruskal-Wallis e post-hoc de Dunn, e ANOVA two-way e post-hoc Bonferroni foram utilizados na análise estatística. Apesar das poucas diferenças significativas encontradas no desempenho dos sistemas adesivos utilizados, pôde-se observar a tendência ao aumento da microinfiltração marginal nos grupos submetidos especificamente a termociclagem. Por outro lado, a formação de fendas axiais apresentaram progressivamente maior largura nos grupos submetidos a termociclagem, carga cíclica e termociclagem+carga cíclica. Concluise que os sistemas adesivos avaliados apresentaram efetividade adesiva similar quando foram submetidos a estresse térmico e mecânico.
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Antunes, Alberto Nogueira da Gama. "Avaliação de adesivos autocondicionantes contemporâneos = efetividade da união dentina-adesivo em função do tempo de armazenamento em água." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288198.
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Orientador: Mário Fernando de GóesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo do estudo foi avaliar a resistência à tração e nanoinfiltração de adesivos autocondicionantes unidos à dentina em função do período de armazenamento em água. Cinquenta molares humanos foram aleatoriamente distribuídos em cinco grupos com 10 dentes cada, de acordo com o adesivo: Single Bond 2, Easy One, Silorane (3M ESPE), Bond Force (Tokuyama) e Adhese One (Ivoclair Vivadent). O esmalte oclusal foi seccionado para obter uma superfície plana em dentina. Os adesivos foram aplicados sobre a superfície da dentina de acordo com as orientações de cada fabricante. Um bloco de resina composta foi construído sobre cada dente, armazenados por 24 horas em água a 37ºC, seguidos pelo seccionamento e obtenção de corpos-de-prova com o formato de palitos com área de secção transversal de 0,8±0,1mm2. Foram usados 5 palitos de cada dente (n=5) em cada período de armazenamento, 24h, 3 e 6 meses, para o teste de resistência à tração (Instron, 0,5mm/minuto). O padrão de fratura foi analisado em microscópio eletrônico de varredura. Três palitos de cada grupo (n=5), em cada período de armazenamento, foram imersos em prata amoniacal para a análise da região da união. Os valores médios obtidos no ensaio de tração (MPa) e nanoinfiltração (%) foram submetidos à Análise de Variância e teste de Fischer (p<0,05). Os valores da resistência à tração (MPa) e nanoinfiltração (%) nos períodos de 24h, 3 e 6 meses foram, respectivamente: Single Bond 2 (48,78, 37,24 e 30,32), (4,78, 4,79 e 6.14); Easy One (48,55, 39,71 e 29,96), (3,22, 2,51 e 4,87); Silorane (41,77, 36,5 e 26,27), (0,77, 0,79 e 2,18); BondForce (39,10, 34,44 e 22,54), (4,28, 4,67 e 13,10); Adhese One (24,65, 24,48 e 16,69), (3,14, 2,93 e 6,74). A resistência à tração do Adhese One foi estatisticamente diferente e inferior aos demais adesivos nos 3 períodos de armazenamento. Single Bond 2, Silorane e BondForce apresentaram resistência à tração estatisticamente diferentes nos períodos de 24h e 6 meses, enquanto que o Easy One e o Adhese One não foram diferentes estatisticamente nos mesmos períodos. O valor médio da nanoinfiltração do Silorane foi inferior e diferente estatisticamente em relação aos demais adesivos, que não apresentaram diferenças entre si no período de 24h. O adesivo BondForce apresentou o maior valor de infiltração de prata em relação aos demais adesivos com a exceção do Adhese One. Os adesivos Single Bond 2, Easy One e Silorane não apresentaram diferenças estatisticamente significantes entre si. O Silorane, BondForce e Adhese One apresentaram valores estatisticamente diferentes em relação ao período de 24h e 6 meses de armazenamento, enquanto que o Single Bond 2 e o Easy One não apresentaram diferenças no mesmo período de tempo. A fratura coesiva na camada de adesivo foi o padrão predominante para os adesivos autocondicionantes nos diferentes tempos de armazenamento. O Single Bond 2 mostrou um padrão de fratura misto, distribuído nas regiões da base da camada híbrida, coesiva no adesivo, dentina, camada híbrida e resina composta nos 3 períodos de armazenamento
Abstract: The aim of this study was to evaluate the tensile strength and nanoleakage of adhesives to dentin surface according to water storage period. Fifty human molars were randomly assigned to five groups of 10 teeth each, according to the adhesive Single Bond 2, Easy One, Silorane (3M ESPE), Bond Force (Tokuyama) and Adhese One (Ivoclair Vivadent). The occlusal enamel was sectioned to obtain a flat dentin surface. The adhesives were applied on the dentin surface according to manufacturer' s instruction. A composite block was built-up on each flat dentin, stored for 24h in water at 37°C, followed by sectioning to obtain beams with crosssectional area of 0.8 ± 0.1mm2. It was used 5 beams from each tooth (n=5) at each storage period - 24h, 3 and 6 months - to evaluate the tensile strength (Instron, 0.5mm/minute). The fracture pattern was analyzed in scanning electron microscope. Three beams of each group (n=5) in each storage period were immersed in ammoniacal silver nitrate to evaluate the nanoleakage. The average values obtained in tensile test (MPa) and nanoleakage (%) were submitted to ANOVA and Fischer's test (p<0.05). The tensile strength (MPa) and nanoleakage (%) values for 24h, 3 and 6 months were: Single Bond 2 (48.78, 37.24 and 30.32), (4.78, 4.79 and 6.14); Easy One (48.55, 39.71 and 29.96), (3.22, 2.51 and 4.87); Silorane (41.77, 36.5 and 26, 27), (0.77, 0.79 and 2.18); BondForce (39.10, 34.44 and 22.54), (4.28, 4.67 and 13.10); Adhese One (24.65, 24.48 and 16.69), (3.14, 2.93 and 6.74). The tensile strength of Adhese One was inferior and statistically different from the other groups on the three periods of storage. Single Bond 2, Silorane Bond Force 24h tensile strength values showed statistically difference to the 6 months groups, while the Easy One and One Adhese were not statistically different in the same periods. The nanoleakage of Silorane was lower and statistically different compared to the other adhesives, which do not differ from each other within 24 hours. The adhesive Bond Force showed the highest infiltration of silver compared to Easy One and Silorane while it was not statistically different from Single Bond 2 and Adhese One other adhesives with the exception of Adhese One and Single Bond 2. The Silorane, BondForce Adhese One showed 6 months nanoleakage values statistically different from 24h, but Single Bond 2 and Easy One presented no differences in the same period. A cohesive failure in adhesive layer was the predominant pattern of self-etching adhesives in three storage periods. The Single Bond 2 showed a mixed fracture pattern, distributed in hybrid layer base, cohesive in adhesive, dentin, hybrid layer and composite resin in three storage periods
Doutorado
Materiais Dentarios
Doutor em Materiais Dentários
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Young, Eleanor Dawn, and ellie@goldstreetstudios com au. "Mechanisms of Controlling Colour and Aesthetic Appearance of the Photographic Salt Print." RMIT University. Applied Science, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080901.142948.
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Abstract The salt print is an important part of photography, both in its historic value and in the tonal range it can provide. This tonal range is greater than any other photographic printing process available to date attributed to the inherent masking ability of the metallic silver. However the intrinsic production problems have made it a 'forgotten' process. There are five key problems. 1. The difficulties in achieving the potential extensive tonal range. 2. The varying colour of the print. 3. Staining that appears in the print, during and after processing. 4. Instability and longevity of the salt print. 5. Contradictory and inaccurate information in material published on the salt print. Although the emphasis of the research is on exploring and controlling the colour and tonal range, the staining problems and stability of the print are also addressed. The materials used for contact negatives today vary in both capture and output, from analogue film processed in the traditional wet darkroom to a variety of transparent film printed from digital files. Inadequate density and tonal range can affect all types of negatives. To provide sufficient exposure time for the salt prints extended tonal range adjustments to the negative were necessary. These long exposures then converted sufficient silver salts to the image making metallic silver, utilising the intrinsic self-masking process. Ultimately this research has uncovered ways to control colour and tonal range and certain aesthetic qualities of the salt print, while simultaneously resolving some of the conflicts in published information. Accurate and consistent methods of processing eliminate staining, providing some stability to the print. The activities and steps carried out to make a salt print are manual; precise duplication is therefore almost unattainable. Nevertheless, although tests on a densitometer may display numeric differences, visual differences are barely noticeable.
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Parastouk, Yasemin. "The Effect Of Ploidy Level On Plant Regeneration In Sugar Beet (beta Vulgaris L.)." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607581/index.pdf.
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ABSTRACT
Three different genotypes of sugar beet (diploid, triploid and tetraploid)4 varieties from diploid and triploid genotypes Soraya (KWS8123) and Leila (diploid), Visa (H68121) and Kassandra (triploid) and 2 lines from tetraploid genotype Ç
BM315 and EA2075 (tetraploid) were used for investigating the effects of ploidy level on plant regeneration. Within three sugar beet genotypes, with respect to the treatments, triploids or tetraploids were found to respond to treatments significantly different when compared with diploids. The responses of polyploids were superior over the responses of diploids. Moreover, varieties from same genotype responded differently to treatments. Two types of calli were obtained
one white and friable with regenerative capacity and the other green and compact with no regenerative capacity. Concentration of sucrose on callus development was observed to be important. High concentration of sucrose (30 g/L) was found to cause discoloration and irresponsiveness of formed calli at callus enlargement and subsequent shoot regeneration stages. Therefore, low concentration (10 g/L) is advised to be used at these stages
although this caused less callus induction. Although initially used for the prevention of tissue discoloration, L-ascorbic acid inclusion into the medium was found to be positively affecting the regeneration capacity. When used at 20 mg/100 mL concentration, the only two spontaneous shoots from the tetraploid EA2075 line were obtained. Subsequently, these shoots were successfully rooted and whole plants were obtained. The effect of silver nitrate, in combination with L-ascorbic acid, on the prevention of sugar beet tissue discoloration was investigated. Unfortunately, the symptoms of discoloration did not diminish. Moreover, callus formation was reduced and the subsequent shoot recovery could not be achieved. Since a total of 3456 explants were used during this study, and only 2 whole plants were regenerated, the efficiency of plant recovery was calculated as a rather low value of 0.058 %.
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Linard, Marco AntÃnio BasÃlio. "Perfil mineral e proteico do plasma seminal de coelhos." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12861.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorSeminal plasma is the fluid portion of semen and its presence positively affects the survival and parameters of sperm motility in rabbits. This study aimed (i) to verify the seminal concentrations of sodium, chloride and citric acid as a function of collection month, the color and aspect of the ejaculate, and to find the frequency of ejaculations with the presence of gel fraction, color and aspect of the semen of rabbits on tropical climate, (ii) to meet monthly protein spots and their possible correlation with seminal and biochemical parameters in rabbits. 20 rabbits of New Zealand White, raised in the flat-deck, fed commercial feed were used. The samples were collected twice a week, and then evaluated for volume, color, aspect, vigor, motility and sperm concentration. After the evaluations, the samples were centrifuged to obtain seminal plasma, which was stored in eppendorfs tubes at -18 oC. A monthly seminal plasma pool of each animal was made to evaluate the concentrations of sodium, chloride, citric acid and proteins. Significant monthly variations were found (p <0.05) in the concentrations of sodium, chloride and citric acid in the seminal plasma of rabbits. All mineral constituents analyzed suffered significant influence (p <0.05) by the color of the ejaculate, and the highest concentrations were found in the white-yellowish ejaculates. Correlation studies found a high and significant association between concentrations of sodium and vigor (r = 0.80, p <0.001), and between sperm concentration and citric acid (r = -0.64, p <0.02). Most of the ejaculates of rabbits showed no gel fraction. The results also showed that the white and milky ejaculate are the most common for the species. It was also observed an average concentration of 2.73 Â 0.31 mg / dl total protein in samples of seminal plasma. From the quantification of total protein were prepared two-dimensional electrophoresis gels stained SDS-PAGE with silver nitrate, with a pH gradient between 3 â 10, mesh 15% and a concentration of 100 mg of protein per sample for each month. Gels were analyzed with the Image Master 2D Platinum 6.0. Â software. The gel containing the most spots (555 spots) was the gel of the month of May, and the gel with fewer spots (71 spots) was observed in January, but no effect of month on the amount of spots was detected. The majority of spots present in seminal plasma of rabbits have pI below 8, and these spots, about 40% have pI acid, the distribution of the spots as a function of pI was homogeneous throughout the year. The distribution of spots depending on the molecular weight widely varied between the months. Except of a few months, most of the protein had a molecular weight above 100 kDa. The number of protein spot positively and moderately correlated with total protein (r = 0.57, p <0.05) and citric acid (r = 0.59, p <0.05). In silico analysis of 1411 protein spots found compatible proteins with the Swiss-Prote database and TrEMBL (UniProtKB). It is concluded that the composition of the seminal plasma of rabbits showed a broad monthly variation and ejaculated with high concentrations of citric acid are undesirable. In addition, the protein profile of rabbits has great affinity of the proteins to acidic and high molecular weight, no influence of the months of the year on the amount of protein spots identified were found and bioinformatics analysis tool does not provide consistent results with those obtained gel electrophoresis, but it allows an estimate of the probable proteins that can be found.
O plasma seminal representa a porÃÃo fluida do sÃmen e sua presenÃa afeta positivamente a sobrevivÃncia e os parÃmetros de motilidade espermÃtica em coelhos. Este trabalho teve como objetivos (i) verificar as concentraÃÃes seminais de sÃdio, cloretos e Ãcido cÃtrico em funÃÃo do mÃs de coleta, da cor e do aspecto do ejaculado, e encontrar a frequÃncia de ejaculados com presenÃa de fraÃÃo gel, cor e aspecto do sÃmen de coelhos criados em clima tropical; (ii) conhecer os spots proteicos mensais e suas possÃveis correlaÃÃes com parÃmetros seminais e bioquÃmicos de coelhos. Foram utilizados 20 coelhos da raÃa Nova ZelÃndia Branca, criados em sistema flat-deck, alimentados com raÃÃo comercial. Os ejaculados foram coletados duas vezes por semana, e logo avaliados quanto ao volume, cor, aspecto, vigor, motilidade e concentraÃÃo espermÃtica. ApÃs as avaliaÃÃes os ejaculados foram centrifugados para obtenÃÃo do plasma seminal, que foi acondicionado em tubos eppendorfs a -18 oC. Um pool mensal de PS de cada animal foi feito para avaliaÃÃo das concentraÃÃes de sÃdio, cloretos, Ãcido cÃtrico e proteÃnas totais. Foram constatadas variaÃÃes mensais significativas (p<0,05) nas concentraÃÃes de sÃdio, cloretos e Ãcido cÃtrico no plasma seminal de coelhos. Todos os constituintes minerais analisados sofreram influencia significativa (p<0,05) da cor do ejaculado, e as concentraÃÃes mais elevadas foram constatadas nos ejaculados de cor branco-amarelada. O estudo de correlaÃÃes encontrou associaÃÃo alta e significativa entre as concentraÃÃes de sÃdio e vigor (r=0,80; p<0,001), bem como entre a concentraÃÃo espermÃtica e o Ãcido cÃtrico (r=-0,64; p<0,02). A maior parte dos ejaculados de coelhos nÃo apresentaram a fraÃÃo gel. Os resultados tambÃm mostraram que o ejaculado de cor branca e de aspecto leitoso sÃo os mais comuns nessa espÃcie. TambÃm foi verificado uma concentraÃÃo mÃdia de 2,73 Â0,31 μg/dl de proteÃnas totais nas amostras de plasma seminal. A partir da quantificaÃÃo das proteÃnas totais foram confeccionados dois gÃis de eletroforese bidimensional SDS-PAGE corados com nitrato de prata, com gradiente de pH entre 3 â 10, malha de 15% e uma concentraÃÃo de 100 μg de proteÃnas por amostra, para cada mÃs. Os gÃis foram analisados no software Image Master 2D Platinum 6.0. Â. O gel que continha o maior nÃmero de spots (555 spots) foi o do mÃs de maio, e o gel com menor nÃmero spots (71 spots) foi verificado em janeiro, mas nÃo houve efeito do mÃs sobre a quantidade de spots detectados. A maioria dos spots presentes no plasma seminal de coelhos tem pI abaixo de 8 e, destes spots, cerca de 40% tem pI Ãcido, a distribuiÃÃo dos spots em funÃÃo do pI foi homogÃnea ao longo do ano. A distribuiÃÃo dos spots em funÃÃo do peso molecular variou amplamente entre os meses. Com exceÃÃo de alguns os meses, a maioria das proteÃnas apresentaram peso molecular acima de 100 kDa. O nÃmero de spot proteicos correlacionaram-se moderada e positivamente com as proteÃnas totais (r=0,57; p<0,05) e com o Ãcido cÃtrico (r=0,59; p<0,05). A anÃlise in silico dos spots encontrou 1.411 proteÃnas compatÃveis com os bancos de dados Swiss-Prote e TrEMBL (UniProtKB). Concluiu-se que a composiÃÃo do plasma seminal de coelhos apresentou ampla variaÃÃo mensal e que ejaculados com alta concentraÃÃo de Ãcido cÃtrico sÃo indesejÃveis. AlÃm disso, o perfil proteico de coelhos apresenta grande parte das proteÃnas com afinidade a meio Ãcido e com alto peso molecular, nÃo houve influencia de meses do ano sobre a quantidade de spots proteicos detectados, e devido à ausÃncia de dados sobre coelhos, a ferramenta de anÃlise bioinformÃtica nÃo ofereceu resultados coerentes, mas permite uma estimativa das provÃveis proteÃnas que podem ser encontradas.
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Paudel, Yadab Kumar. "Tribological properties of adaptive [molybdenum nitride/molybdenum sulfide/silver] nanocomposite coatings /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1597633321&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Wickens, David John. "Nanocomposite zirconium nitride/silver coatings to combat external bone fixation pin infections." Thesis, Manchester Metropolitan University, 2014. http://e-space.mmu.ac.uk/280/.
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External bone fixation provides rehabilitation for severely broken limbs. The nature of the pins compromises the skin at the entry point and creates an interface that is prone to infection by opportunistic pathogens. Pin tract infections possess one of the highest infection rates of implanted devices. Infection induces further physical and psychological stress to the patient as well as increasing healthcare costs. If the infection can be prevented there is the potential to reduce patient distress, related healthcare costs and the overuse of antibiotics. Using magnetron sputtering, zirconium nitride/ silver coatings were co-deposited onto medical grade 316L stainless steel. Combining the hard wearing properties of ZrN and the broad spectrum antimicrobial properties of silver, these nanocomposite coatings displayed the potential to combat pin tract infections. The coatings were characterised in terms of surface topography, morphology, chemical composition, physicochemistry, antimicrobial efficacy and bacterial retention towards Staphylococcus aureus and Staphylococcus epidermidis. The Ti-ZrN/Ag coatings displayed an increase in nanotopography in comparison to the underlying stainless steel but no increase in microtopography was observed. The silver was deposited as particles in the coatings and the silver content increased linearly with an increase in magnetron power. The most antimicrobial coating was not necessarily the one with the most silver. The Ti-ZrN-Ag coatings were tested against two of the most commonly isolated bacteria from pin tract infections; Staphylococcus aureus and Staphylococcus epidermidis. The Ti-ZrN/Ag coatings displayed an effective contact kill towards both microorganisms, with the silver causing multiple bacterial physiological changes, reducing bacterial respiration and compromising the cell membranes. An increase in silver content displayed an increase in short term antimicrobial efficacy (< 1 hour) whereas following 24 hours contact time (humid conditions) no bacteria survived on the surfaces containing silver, regardless of the concentration. To replicate an in vivo environment, the Ti-ZrN/Ag coatings were characterised in the presence of a blood conditioning film. The underlying topography of the surfaces were found to have an effect on the physicochemical properties of the adsorbed conditioning film. The surface chemistry also affected the adsorption of the conditioning film, with differences in surface morphology between the stainless steel and ZrN in comparison to the ZrN/Ag coatings. The short term antimicrobial activity was reduced when the surfaces were dry (similar to the environment the pin will encounter outside the body), however keeping the environment humid (similar to the environment the pin will encounter inside the body) the coatings demonstrated an antimicrobial effect over 24 hours. Multifractal analysis was used to provide a method to quantify bacterial dispersion and density by analysing the micrographs of retained bacterial cells on the ZrN/Ag surfaces. Multifractal analysis found that with increasing silver content the densities of the retained S. aureus cells remained similar whereas the S. epidermidis decreased. S. aureus demonstrated a more heterogeneous dispersion and S. epidermidis a more homogeneous cell spread. Using this quantitative data acquisition method on the retention behaviour of bacteria displays potential to rapidly assess the surface - bacteria interfacial characteristics of biomaterials, thus, aiding improvement of surface characteristics of an implant at early research and development stages. These results demonstrate the importance of thorough characterisation, microbiological and conditioning film testing when designing new coatings. This work has demonstrated that Ti-ZrN/Ag coatings have the potential to provide an actively antimicrobial pin coating in situ.
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Stone, D'Arcy S. "Tribological investigation of nanocomposite thin films of transitional metal nitrides with silver inclusions." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/768.
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In this tribological study, a temperature dependent inquiry of the changes in chemistry and crystal structure of two selected double metal oxides is undertaken. It is known that chameleon coatings of Mo2N/Ag/MoS2 produce a friction coefficient of 0.1 from wear testing at 600 °C for 300,000 cycles. The low friction is attributed to the formation of silver molybdates layers, a lubricious double-metal oxide, in the coating. Double-metal oxides consisting of a group 6 transitional metal and silver (silver molybdate (Ag2Mo2O7) and silver tungstate (Ag2WO4)) were used for this investigation. Thin films and powders were investigated using high temperature x-ray diffraction, high-temperature Raman spectroscopy and differential scanning calorimetry in tandem with sliding tests from 25 to 600 °C. Our results were compared to external ab-initio molecular dynamic simulations performed elsewhere to qualify experimental results. The layered atomic structure of silver molybdate facilitates sliding, resulting in a low coefficient of friction (<0.2) from 300-500 °C. Unlike Ag2Mo2O7, however, Ag2WO4 does not possess a layered atomic structure and produced coefficients of friction (>0.4) in all temperature ranges between room temperature and 500 °C. Applying the knowledge gained from prior studies of the intrinsic properties of double metal oxides of group 6, chameleon coatings consisting of group 5 transitional metal nitrides (vanadium nitride, niobium nitride, and tantalum nitride) with silver inclusions were created using unbalanced magnetron sputtering to investigate their potential application as adaptive, friction reducing coatings. The coatings were tribotested against a Si3N4 counterface in the 22 to 1000 °C temperature range. In-situ Raman Spectroscopy measurements were taken during heating and wear testing at 700 °C to identify the evolution of phases in the coatings' surfaces and in the wear track. The chemical and structural properties of the coatings were also characterized before and after wear testing using x-ray diffraction. At higher temperatures, oxygen, silver and the transition metals react on the surface to form potentially lubricious double oxide phases (silver vanadate, silver niobate and silver tantalate). All coatings performed similarly up to 750 °C. The VN/Ag coating, however, had a lower coefficient of friction at 750 °C comparatively to TaN/Ag and NbN/Ag, likely due to its reported lower melting temperature (450 °C) and its layered crystal structure.
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Ribicki, Ariane Caroline. "Síntese e caracterização de novos materiais híbridos orgânicos- inorgânicos visando diferenciadas aplicações." Universidade Estadual de Ponta Grossa, 2018. http://tede2.uepg.br/jspui/handle/prefix/2746.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Este trabalho reporta a preparação, caracterização e aplicação de novos materiais híbridos silsesquioxanos, obtidos a partir do método sol-gel de síntese, que consistiu em reações de hidrólise e policondensação dos precursores a base de sílica e por meio da reação SN2 dos precursores com os ligantes orgânicos 4-(aminometil)piridina e imidazol, obtendo assim o Si4ampy+Cl- e o SiImi+Cl-, respectivamente. Os silsesquioxanos nitrogenados foram submetidos a técnicas de caracterização como RMN, DRX, MEV, UV-VIS, FTIR e BET para confirmação das estruturas apresentadas nesta tese, bem como a organofuncionalização dos materiais. No caso do Si4ampy+Cl-, verificou-se dois sítios de reação com ligação do carbono –α do grupo npropil ao nitrogênio do grupamento amino e do nitrogênio do anel piridínio, com proposta de dois arranjos da cadeia carbônica. O Si4ampy+Cl- foi aplicado na construção de eletrodos modificados com a NiTsPc, utilizando a técnica LbL para a fabricação de filmes finos. O eletrodo na configuração (Si4ampy+Cl-/NiTsPc)11 foi aplicado como sensor eletroquímico sensível ao nitrito, com r = 0,999 na faixa de 0,113 mmol L-1 a 0,860 mmol L-1, LD e LQ de 0,026 mmol L-1 e 0,127 mmol L-1, respectivamente e os valores de desvio-padrão foram de aproximadamente 3%, estando de acordo com recomendações da ANVISA e Inmetro. Outro emprego do Si4ampy+Cl- foi na estabilização de nanopartículas de prata para fabricação de filmes finos. A presença das Ag-NPs/Si4ampy+Cl- foi confirmada por UV-VIS, pela banda plasmon em 426 nm, as quais apresentaram distribuição com tamanho aproximado entre 12 e 131 nm, constatado por DLS e corroborado por MEV, apresentando boa estabilidade (= +43,4 mV). As Ag-NPs/Si4ampy+Cl- mostraram-se promissoras na modificação do eletrodo ITO com a NiTsPc, apresentando um crescimento linear do filme LbL e processos redox referentes à oxirredução do centro metálico e à oxidação do anel da ftalocianina vistos por voltametria cíclica, exibindo a capacidade do eletrodo modificado (Ag-NPs/Si4ampy+Cl-/NiTsPc)7 em eletrocatalisar espécies químicas. No geral, os eletrodos modificados (Si4ampy+Cl-/NiTsPc)11 e (Ag-NPs/Si4ampy+Cl-/NiTsPc)7 proporcionaram aprimoramento na resposta de corrente anódica e redução do potencial de oxidação comparado com o eletrodo não-modificado (ITO) em presença de nitrito. O SiImi+Cl- que foi destinado a adsorção dos íons Cu2+, Cd2+ e Ni2+, apresentou capacidade de troca iônica de 2,944 mmol g-1, resultado considerado excelente de acordo com a literatura para a aplicação proposta. Os resultados de adsorção mostraram a viabilidade do uso do SiImi+Cl- como eficiente material adsorvente, exibindo maior afinidade para os íons Cu2+ em pH 4. Ao aplicar os modelos de Langmuir e Freundlich nas isotermas de adsorção, verificou-se que tanto o pH como a natureza do íon são fatores que influenciaram o ajuste das isotermas aos modelos propostos.
This work reports the preparation, characterization and application of new silsesquioxanes hybrid materials obtained from the sol-gel synthesis method, which consisted of hydrolysis and polycondensation reactions of the silica-based precursors and SN2 reaction of the precursors with 4-(aminomethyl)pyridine and imidazole groups, obtaining Si4ampy+Cl- and SiImi+Cl-, respectively. Silsesquioxanes with nitrogen groups were characterized by techniques such as NMR, XRD, MEV, UV-VIS, FTIR and BET to confirm the structures presented in this thesis, as well as the materials functionalization. In the case of Si4ampy+Cl- two reaction sites were observed with carbon-α of the n-propyl group bonding with the amino group and the pyridinium ring, having as proposal two arrangements of the carbonic chain. The Si4ampy+Cl- was applied in the construction of electrodes modified with NiTsPc using the LbL technique for the thin films manufacture. The electrode in the configuration (Si4ampy+Cl-/NiTsPc)11 was applied for nitrite electrochemical sensor, with r = 0.999 in the range of 0.113 mmol L-1 to 0.860 mmol L-1, LD and LQ of 0.026 mmol L-1 and 0.127 mmol L-1, respectively and standard deviation values of approximately 3%, according to recommendations of ANVISA and Inmetro. Another use of Si4ampy+Cl- was the stabilization of silver nanoparticles for the thin films production. The presence of Ag-NPs/Si4ampy+Cl- was confirmed by UV-VIS technique by the plasmon band at 426 nm which presented a distribution with approximate size between 12 and 131 nm, verified by DLS and MEV, presenting good stability (= +43.4 mV). The Ag-NPs/Si4ampy+Cl- showed promising in the modification of the ITO electrode with NiTsPc, showing linear growth of the LbL film and redox processes related to the oxidation of the metal center and to the oxidation of the phthalocyanine ring observed by cyclic voltammetry, exhibiting the performance of the modified electrode (Ag-NPs/Si4ampy+Cl-/NiTsPc)7 to electrocatalyse chemical species. In general, the modified electrodes (Si4ampy+Cl-/NiTsPc)11 and (Ag-NPs/Si4ampy+Cl-/NiTsPc)7 obtained an improvement in the anodic current response and reduction of the oxidation potential compared to the unmodified electrode (ITO) in the presence of nitrite. The SiImi+Cl- was used to adsorb Cu2+, Cd2+ and Ni2+ ions and presented ion exchange capacity of 2.944 mmol g-1, which was considered excellent according to the literature for the proposed application. The adsorption results showed the viability of using SiImi+Cl- as an efficient adsorbent material, exhibiting a higher affinity for the Cu2+ ions at pH 4. Applying the Langmuir and Freundlich models to the adsorption isotherms, it was verified that both the pH as the nature of the ion are factors that influenced the adjustment of the isotherms to the proposed models.
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Zahidi, Assou. "Etudes structurales et dynamiques de complexes macrocycliques par rmn heteronucleaire." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13171.
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Etude de la complexation de cations et d'anions par des ligands synthetiques a l'aide de la rmn heteronucleaire (**(6)li, **(7)li, **(13)c, **(14)n, **(15)n, **(19)f, **(31)p, **(35)cl et **(109)ag) et de mesures d'effet overhauser homo- et heteronuclaires
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Findik, Hamide. "Potassium Permanganate/ Carboxylic Acid/ Organic Solvent: A Powerful Reagent For C-c Bond Formation, Aryl Coupling Reactions And Enone Oxidation Ipso-nitration Of Arylboronic Acids With Silver Nitrite/ Tmscl." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610472/index.pdf.
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The first part of the thesis presents the KMnO4/ carboxylic acid/ organic solvent which is a powerful reagent for C-C bond formation, aryl coupling reactions and enone oxidation. The a¢-acetoxylation of enones and the a-acetoxylation of aromatic ketones were carried out with potassium permanganate and acetic acid, in which acetoxylation products were obtained in 74-96% yields. The same reaction was carried out with carboxylic acids other than acetic acid, which furnished corresponding acyloxy ketones with the same regioselectivity. For the first time, formyloxylation products were synthesized in a 61-85% yield by using formic acid. The potassium permanganate and acetic acid method was also used for aryl coupling reactions. The reaction of arylboronic acids and aryl hydrazines in benzene with potassium permanganate and acetic acid in turn furnished biaryls in a 85-96% yield. We showed that potassium permanganate/carboxylic acid/organic solvent behaves as manganese(III) acetate. In the second part of the thesis, ipso-nitration of arylboronic acids with AgNO2/ TMSCl was performed. Nitration of aromatic compounds is one of the most extensively studied reactions, and nitroaryl moieties play key roles in the physical and chemical properties of many target molecules in organic synthesis. For electrophilic nitration of aromatic compounds, a wide variety of reagents are available to date. Most of them are very strong nitrating agents and often lead to further nitration and mixture of isomers. Since most nitrating agents are oxidants, oxidation of other functional groups can also occur, giving a mixture of products. Thus, a search for milder and selective nitrating agents is a good research goal. In this work, we aimed to apply AgNO2/ TMSCl system to ipso nitration of arylboronic acids.
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Horn, Jacqueline Marie. "Design of a Wearable Flexible Resonant Body Temperature Sensor with Inkjet-Printing." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703340/.
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A wearable body temperature sensor would allow for early detection of fever or infection, as well as frequent and accurate hassle-free recording. This thesis explores the design of a body-temperature-sensing device inkjet-printed on a flexible substrate. All structures were first modeled by first-principles, theoretical calculations, and then simulated in HFSS. A variety of planar square inductor geometries were studied before selecting an optimal design. The designs were fabricated using multiple techniques and compared to the simulation results. It was determined that inductance must be carefully measured and documented to ensure good functionality. The same is true for parallel-plate and interdigitated capacitors. While inductance remains relatively constant with temperature, the capacitance of the device with a temperature-sensitive dielectric layer will result in a shift in the resonant frequency as environmental or ambient temperature changes. This resonant frequency can be wirelessly detected, with no battery required for the sensing device, from which the temperature can be deduced. From this work, the optimized version of the design comprises of conductive silver in with a temperature-sensitive graphene oxide layer, intended for inkjet-printing on flexible polyimide substrates. Graphene oxide demonstrates a high dielectric permittivity with good sensing capabilities and high accuracy. This work pushes the state-of-the-art in applying these novel materials and techniques to enable flexible body temperature sensors for future biomedical applications.
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Chen, Ningxin. "Processus de transfert de l’eau et des contaminants agricoles dans la zone non saturée de la craie." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS588.
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L'aquifère de la craie est une ressource importante d'eau potable mais sa qualité s’est dégradée à cause de l'utilisation d'engrais et de pesticides. La craie est un milieu hétérogène avec double porosité : matrice et fractures, et souvent recouverte par l’argile à silex. Le but de cette étude est de caractériser le processus de transfert d'eau et de contaminants dans la zone non saturée (ZNS) et de comprendre comment ils sont impactés par la ZNS. Cette étude est réalisée sur la carrière souterraine de Saint-Martin-le-Nœud. La craie est recouverte par une couche d’argile à silex d’épaisseur variable. La carrière est à la limite de la ZNS et la zone saturée permettant d’avoir un accès direct à la ZNS. Au plafond, l’eau percole et dans la partie basses, la nappe affleure formant ainsi des lacs. Les propriétés hydrochimiques et hydrodynamiques de 16 sites (lac+percolation) ont été suivies dans le temps. La variation spatio-temporelle des eaux souterraines montre : l'eau et les contaminants sont transférés principalement par la matrice (~1 m/an) et une partie transférée par les fractures (~100 m/an) et ces vitesses varient en fonction du type de molécule ; les transferts sont principalement sous l'effet piston avec une partie en transfert direct ; le front de contaminants descend vers la nappe plus profonde avec une vitesse de 1m/an. La ZNS impactent le transfert d’eau et de contaminants et la dégradation des pesticides : plus la nappe est profonde, moins elle est contaminée ; l’argile à silex favorise la dégradation des pesticides en créant une nappe perchée en proche surface ; l’argile à silex accélère les transferts d’eau et des contaminants par les chemins préférentielsThe chalk aquifer is an important source of drinking water, and the quality of which has deteriorated in recent decades, due to the use of fertilizers and pesticides on the surface. Chalk is a heterogeneous medium because of its double porosity: matrix and fractures, and often covered by superficial formations. The purpose of this thesis is to characterize the transfer processes of water and contaminants in the unsaturated zone (UZ), and to understand how they are influenced by the properties of the UZ. This study is carried out on the underground quarry of Saint-Martin-le-Nœud. The chalk is covered by a layer of clay of varying thickness. The quarry is at the boundary between the UZ and the saturated zone (ZS) allows direct access to the ZNS. On the ceiling, the water percolates and in the lower parts watertable forms lakes. The hydrochemical and hydrodynamic properties of 16 sites (lake + percolation) were observed for several years. The study of the spatio-temporal variation of groundwater shows: water and contaminants are transferred mainly by the matrix (~1 m / year) with a part transferred by fractures (~100 m / year) and these transfer rates vary depending on the type of molecule (different between solute and organic molecule); the transfers are mainly results of the piston flow with a small part of direct transfer. Characteristics of the UZ’ effect on water and contaminants transfers and pesticide degradation: deeper water table has fewer contaminants; clay-with-flints promotes pesticide degradation by creating a perched sheet in the near surface; clay-with-flints accelerates the transfer of water and contaminants through preferential paths
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Chen, Chih-Kant, and 陳志綱. "Fabrication of Silver Nanostructure Using ArF-excimer-laser Photoreduction of Silver Nitrate." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/82385768080636709983.
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碩士國立中正大學
光機電整合工程所
97
Techniques for fabricating silver nanostructures from a silver nitrate film can be divided into two main categories. One is realized by a direct photochemical reaction and the other is accomplished first through a photoreduction process to generate the initial silver pattern then followed by the method of selective electroless plating to grow the resulting metallic pattern. The former has been successfully employed to fabricate nanosctures with various forms such as wires, spheres, cubes, rods, tubes and plates. These designate nanostructures are applicable to surface enhance Raman spectroscope. Generally, the light source is a UV lamp and it takes long to complete the exposing process. The latter, however, utilizes a pulsed Ti:Sapphire or CO2 laser as the light source that can facilitate the exposing process. Taking the merits of laser exposing, the present study employs an ArF excimer laser for fast fabrication of silver nanostructures. Well crystallized silver nitrate films, with thickness ranging from 1000 nm to 700 nm and solidified either on a glass, SiO2 or PET substrate from solutions with various solvents, are first carefully developed. Laser light through a mask is then incident on the prepared silver nitrate film. By adjusting the laser optics, film sizes ranging from 10 m ×10 m to 1 mm × 1 mm can be fabricated. Depending on the laser fluence and exposing time, films with different types of nanostructure can be reduced. With suitable exposing parameters, the reduction film can be in a nanomesh structure that forms a well interconnected network. Thus, the resulting silver film is able to be a very good conductor. Resistivity down to 8.5×10-8 Ωm is obtainable which is close to that of bulk silver (1.67×10-8 Ωm). The mechanism of nanostructure formation and its relation to film conductivity are discussed in this thesis. Besides, to further reduce the film thickness and facilitate the fabrication time, the use of sodium dodecyl sulphate (SDS) as a dispersing agent in preparing silver nitride film is also studied. With this dispersant, the resulting film thickness can be further to 300 nm.
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CHEN, CHIEN-HSUN, and 陳建勳. "A Novel ipso-Nitration of 2-Halothiophenes with Silver Nitrate." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/u4za3r.
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碩士輔仁大學
化學系
105
In this thesis, we provide an efficient ipso-nitration to synthesize 2-nitrothiophene derivatives. The reaction use silver nitrate, a readily available reagent, as the nitration reagent and no additives, such as strong oxidants or transition metal catalysts, are needed for the transformation. 5-Halothiophenes, which containing styryl 82, p-methoxystyryl 84 and p-bromostyryl 92 and iodothienyl 96 substituents, could be converted into the corresponding ipso-nitration products by silver nitrate in toluene or 1,4-dioxane under reflux. Besides, the ipso-nitration of 2-bromothiophene 85 and 87 could render dinitro product 106 when 1,4-dioxane was used as the solvent. In the same condition, 2-bromofuran (104) could be converted into 2-nitrofuran (105) smoothly.
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Kao, Fang-hsin, and 高芳歆. "BLACKENING OF ANODIC FILM OF ALUMINUM IN SILVER NITRATE SOLUTION." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/62208529592210719837.
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碩士大同大學
化學工程學系(所)
92
In the study, the anodic oxide aluminum was electrolyzed in silver nitrate solution. The factors that influence the electrolytic coloring, such as electrolytic coloring time, temperature of electrolytic coloring bath, electrolytic concentration, and coloring voltage were investigated. The conditions to produce the blackest colored film on aluminum were also found out. The results show that the silver nitrate solution is very suitable for black electrolytic coloring, because of the low voltage, short coloring time and low concentration. Besides, the minimum reflectivity of black anodic oxide film was obtained about 2.68 % by spectrophotometer. In addition, the operating condition of coloring bath temperature is the main factor to influence the L-value, reflectivity, film thickness and film microhardness. From the test of dissolution and SEM, the structure of the colored film from the higher coloring bath temperature is looser and softer; and the corrosion resistance is worse than that from lower coloring bath temperature.
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Wan-LingGong and 龔婉菱. "A Kinetic Study of Silver Nitrate and Copper Ion by Replacement Reaction." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/85203475350258416869.
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碩士國立成功大學
電機工程學系
103
This study is probing into the kinetic influence in silver-copper replacement reaction. In order to reduce the contact resistance, copper powder contact each other with the binder, silver nanoparticles. Silver nanoparticles will melt at 200℃ before copper powder is oxidized. This mechanism can not only prevent copper from oxidized, but enhance the conductivity. Silver-copper powder is prepared by replacement reaction. Through changing the content of silver nitrate, the content of dispersant (PVP), reaction time and reaction temperature, the result shows replacement reaction has an impact on the grain size. Moreover, the kinetic study can be analyzed. The conclusion of this study represents when the molar ratio of silver nitrate to copper powder is 1:0.5, using ethylene glycol as solvent, adding 0.5 wt. % PVP, at room temperature, the reduction rate of silver particles could be controlled, and forming nanostructure silver which has obvious branch structure. The dendritic structure silver formed smaller and obvious branch structure. When reaction time is 30 minutes, there is enough time to produce silver nanoparticles, obvious dendritic structure. In the other side, if the temperature of reaction is too low, copper powder can’t be coated completely. A weight percent of silver is more than 95% on the surface by energy dispersive spectrometer analysis. This result shows silver nanostructure covered on copper in a good shape.
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Wu, Chia-Wei, and 吳嘉薇. "The Effect of Incorporating Silver Nitrate on the Properties of Silver/Graphene Nanosheets Composites Produced With Cathodic Plasma Exfoliation." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/m8399n.
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Gama, Raquel Matias. "The effects of silver nitrate on Cicer arietinum L. (C3) and Zea mays (C4) plants." Master's thesis, 2020. http://hdl.handle.net/10451/52473.
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Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, 2020, Universidade de Lisboa, Faculdade de Farmácia.Os nanomateriais foram desenvolvidos há várias décadas e implementados numa ampla gama de aplicações industriais. Atualmente, um dos nanomateriais mais utilizados são as nanopartículas de prata (AgNPs), principalmente no setor agrícola. As AgNPs podem ser produzidas por vários métodos. Um novo método de produção de AgNPs é o uso de plantas ou extratos de plantas para a sua síntese, a chamada “síntese verde”, revelando-se este método ser mais seguro, biológica e ambientalmente, quando comparado aos métodos convencionais de produção - químicos ou físicos. Todavia são escassos os estudos destas AgNPs, quando produzidas via síntese verde, nas plantas C3 e C4. Tendo como objetivo preencher esta lacuna na ciência, esta investigação tem por objetivo estudar o efeito do nitrato de prata (AgNO3) e das AgNPs, produzidas via síntese verde usando Salvia officinalis, nas plantas C3 e C4. Como espécies de plantas C3 e C4 utilizouse Cicer arietinum L. (grão-de-bico) e Zea mays (milho), respetivamente. Este é o primeiro estudo de que temos conhecimento que estudou ambos os tipos de plantas. O estudo empírico foi conduzido no âmbito do programa Erasmus +, na University of Veterinary and Pharmaceutical Sciences, Brno, compreendendo duas etapas. Na primeira etapa, estudou-se o efeito do AgNO3 no grão-de-bico e no milho. Numa segunda etapa, delineou-se a experiência para o estudo do efeito das AgNPs no mesmo tipo de plantas. Só foi possível recolher e tratar os resultados empíricos relativos à primeira etapa (devido à interrupção da investigação na sequência da pandemia COVID-19). Os resultados empíricos obtidos evidenciam que os iões de prata são benéficos para a germinação de ambos os tipos de plantas, sendo o nível de concentração mais benéfico o de 50 mg/L. Este resultado indicia que altas concentrações de AgNO3 podem causar stress oxidativo e inibição do crescimento, levando à morte celular das plantas. Com referência ao efeito das AgNPs, os resultados expectáveis com base na literatura, sugerem que a toxicidade das AgNPs é menor do que a de AgNO3, pois não há acúmulo direto de iões de prata. Assim, é possível gerar menos espécies reativas de oxigénio, menos efeitos negativos nos parâmetros fotossintéticos e obter resultados ainda melhores na germinação das plantas. Relativamente aos metabolitos secundários das plantas, a literatura não é consensual.
Nanomaterials went into development several decades ago and since implemented across a wide range of industrial applications. Nowadays, silver nanoparticles (AgNPs) represent one of the most commonly used nanomaterials, especially in the agricultural sector. There are several methods for producing AgNPs. A new AgNPs production method involves the usage of plants or plant extracts for their synthesis that termed “green synthesis”, which proves to be biologically and environmentally safer, when compared to conventional production methods via chemical or physical means. However, there are only scarce studies about the effects of AgNPs on C3 and C4 plants when produced via green synthesis. In order to fill this gap, this project aims to study the effect of silver nitrate (AgNO3) and AgNPs, produced via green synthesis using Salvia officinalis, on C3 and C4 plants. As C3 and C4 plant species, we made recourse to Cicer arietinum L. (chickpeas) and Zea mays (maize), respectively. To the best of our knowledge, this is the first research to study both types of plants. The empirical study, conducted under the Erasmus + program at the University of Veterinary and Pharmaceutical Sciences, Brno, involved two steps. The first studied the effect of AgNO3 on chickpeas and maize. In a second stage, the experiment was outlined to study the effect of AgNPs on the same plant types. It was only possible to collect and analyse the empirical results relating to the first step (due to the suspension of the research caused by the COVID-19 pandemic). The empirical results obtained demonstrate how silver ions are beneficial for the germination of both types of plants, with the most beneficial concentration level being 50 mg/L. Furthermore, these results indicate how high concentrations of AgNO3 may cause oxidative stress and the inhibition of growth, leading to cell death in plants. With reference to the effects of AgNPs, the results expected according to the literature indicate a lower level of toxicity for AgNPs than for AgNO3 as there is no direct accumulation of silver ions. Applying AgNPs makes it possible to generate fewer reactive oxygen species, less negative effects in terms of the photosynthetic parameters and obtaining even better results for plant germination. Regarding the secondary metabolites of plants due to the effect of AgNPs, the literature does not display any consensual position.
Com o patrocínio da University of Veterinary and Pharmaceutical Sciences, Brno
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Wang, Meng-Ling, and 王孟鈴. "The study of silver nitrate effect on synthesis and properties of polyurethanes containing pyridine." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/37322288812420595161.
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碩士南亞技術學院
材料應用科技研究所
99
This study is mainly to use aromatic 4,4’-diphenylmethane diisocyanate (MDI) as the hard segment and use Polytetramethylene glycol (PTMG) as the soft segment to synthesize the pre-polymer, and then use 1,4-butane diol (1,4-BD) and 2,6-Pyridinedimethanol (2,6-PDM) to act as the chain extender, meanwhile add the silver nitrate content in different proportions. Due to silver ions and 2,6 - pyridine methanol (2,6-PDM) will form coordination bonding to become a polyurethane/ silver nitrate composite materials to improve the impact to the mechanical properties and thermal properties of polyurethane, and it has antibacterial properties. In this study, we use FT-IR analysis spectrum to know the functional group, it shows that polyurethane/ silver nitrate composite materials does successfully synthesized. By the test of X-Ray diffraction, we can know the 28.55° of 2θ angle belongs to the peak value of silver ion crystal. In thermal property, we observed that the pyrolysis temperature of the polyurethane / silver nitrate composite material will rise significantly with the silver nitrate concentration increasing, and the thermal gravity residual rate in 600℃ will also increase with the silver nitrate content increased. Additionally, it can be tell by the experiment results of DSC and DMA that Tg of polyurethane/ silver nitrate composite material will increase with the silver nitrate content increased. In mechanical properties, the tensile strength and elongation at break has the tendency to decrease along with the silver nitrate content increased, but the Young’s coefficient was increased gradually, and then uses EDS analysis to know it contains silver metal element. It can be tell in swelling experiment that swelling property is getting worse along with silver nitrate content increased. In addition, it can be tell by the spectrophotometer that UV resistance will be better along with the silver nitrate content increased. In the antimicrobial tests, we can be tell by the experiment results of Staphylococcus aureus and Klebsiella pneumoniae, its antibacterial effect increase along with the added silver nitrate content increased.
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Lin, Elaine Yi-Hua. "A Study of the Mobility of Silver Ions in Chitosan Membranes." Thesis, 2007. http://hdl.handle.net/10012/3097.
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Chitosan membrane has found applications in biomedical, wastewater treatment, and petrochemical fields that involve the use of silver ions (Ag+). However, mobility of Ag+ in chitosan membranes has seldom been studied. In this study, transport properties of Ag+ in chitosan membranes are studied in-depth, to determine diffusivity coefficient, permeability coefficient, and sorption uptake of Ag+ in chitosan. All parameters are evaluated based on the influence of feed concentration, membrane thickness and operating temperature.
The diffusivity is determined from the time lag obtained from transient diffusion experiments. The permeability is determined from the steady state of permeation experimentally. The diffusivity and corresponding permeability coefficients of Ag+ in chitosan range from to 2.0 10-7 (cm2/s) and from 6.6 10-8 to 2.0 10-7 {mol m/[m2 s (mol/L)]}, respectively, over the conditions tested. Temperature dependencies of these two parameters are found to follow the Arrhenius relationship.
Sorption uptake of the silver salt in chitosan correlates well with the Langmuir isotherm. Also determined from the sorption tests are degree of membrane swelling at different concentrations. This information allows diffusivity coefficients to be determined from the steady state permeation rate. These values of diffusivity are compared with that obtained using the time lag method.
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HUANG, YI-WEI, and 黃益偉. "The Study of Characteristics About Polyvinyl Alcohol-Silver Nitrate Conductive Films Adding Multi-Layer Graphene." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/684vt3.
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碩士國立雲林科技大學
環境與安全衛生工程系
106
This study is produced environmental, flexible conductive film by polyvinyl alcohol with characteristics that has malleable, can be widely decomposed by microorganisms. Then silver nitrate is reduced by the functional groups rich in polyvinyl alcohol to form conductive silver nanoparticles. Finally, a multi-layered graphene is added to the conductive film in a physically mixed manner, and the graphene surface is rich in positive electricity, which helps the silver particles form a silver floe. Preparation of conductive film samples with different ratios of silver nitrate and multilayer graphene, and make a treatment with heat. And through a variety of instrument detection include: Field emission scanning microscope (FE-SEM), UV-VIS spectrometer (UV-VIS), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction analyzer (XRD), heat Heavy loss analyzer (TGA) and four-point probes were used to compare the differences in surface characteristics, transmittance, characteristic functional groups, crystal structure, thermal stability, and conductivity between the samples. This study concluded that the addition of silver nitrate and multilayer graphene will cause the transmittance of the conductive film to decrease, but increasing the amount of silver nitrate and multilayer graphene can increase the conductivity of the conductive film. It was found from the TGA analysis that the addition of silver nitrate resulted in a decrease in the thermal stability of the polyvinyl alcohol, which could be improved by the addition of multilayer graphene.
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Nguyen, Chin. "Research portfolio: a new in-vitro methodology for the study of microleakage of low volume shrinkage composite resin." Thesis, 2011. http://hdl.handle.net/2440/71849.
Full textAbstract:
Microleakage has been defined as the passage of bacteria, fluids, molecules or ions along the tooth-restoration interface (Kidd, 1976). This leakage may be clinically undetectable, but is a major factor influencing the longevity of dental restorations as it causes many severe biological effects on the restored tooth including the recurrence of caries, pulp pathology, hypersensitivity and marginal breakdown (Hersek, 2002). The investigation of microleakage is, therefore, important in the assessment of restorative materials. A variety of in vitro methods have been introduced into the study of microleakage including compressed air, neutron activation, electrochemical, fluid filtration, bacteria and the use of dyes (Karagenς, 2006; Kidd, 1976;Taylor, 1992). In addition, various techniques such as scanning electron microscopy, transmission electron microscopy and electron probe microscopic analysis have been used to image and measure leakage. However, the above specimen preparation techniques are two-dimensional in nature and do not take the whole tooth-restoration interface into account, as some sections obtained randomly are taken to measure microleakage. Over the past few years there have been efforts to investigate microleakage of restorative materials three dimensionally (Gale, 1994; Iwami, 2005; Lyroudia, 2000; Youngson, 1992). However, this methodology was also destructive as images were reconstructed from serial cross-sections of continuously ground surfaces. One of the most advanced techniques in medical imaging in recent years has been the advent of micro-computed tomography (MCT) that can achieve a spatial resolution at the micron level. Recently, the MCT Skyscan 1072 (MCT 1072) has been introduced into dentistry for the study of many subjects including dental materials, dental morphology and dental implants (Bergmans, 2001; Park, 2005; De Santis, 2005). De Santis et al (2005) first used MCT to study microleakage and although these workers introduced a non-destructive method, the model they chose had some weaknesses. From the clinical perspective only flat dentine surfaces were studied rather than definite cavities, as in the clinical situation. Furthermore, no three-dimensional quantitative and qualitative analyses were undertaken. In considering various methods that have been used to study microleakage, the technology of MCT would appear to offer significant advantages over two-dimensional methods involving sectioning of specimens. In order to image microleakage using MCT, an x-ray contrast dye solution is needed. It has been reported that a silver nitrate solution has been the only metal solution that is able to express the microleakage of restorative materials (Besnault, 2003; Taylor, 1992; Taylor, 1993; Tsatsas, 2005). Filtek Silorane (3M ESPE) has been recently introduced into the market and is considered as a low volume shrinkage composite resin. Very little microleakage research has been done for this new material. It is from this fundamental basis that the project evolved, with firstly, the need to explore the potential of using MCT scanning of composite resin restorations and secondly, to develop a suitable study model that can be used effectively with the MCT 1072. Thirdly, qualitative and quantitative microleakage patterns of Filtek Silorane are studied non-destructively and three-dimensionally. As an introduction to this investigation it is necessary to review the adverse effects of microleakage on the restored teeth. In addition, aetiologies and dynamic processes of microleakage will be considered. Furthermore, the current methodologies with their main advantages and disadvantages will be discussed. Having discussed the current thinking on microleakage, there will be a further discussion of x-ray contrast dye solutions and MCT 1072. There will be also an overview of the new version of composite resin namely, Silorane. Finally, the factors that can influence the results of microleakage studies will be reviewed.Thesis (D.Clin.Dent.) -- University of Adelaide, School of Dentistry, 2011
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SHARMA, SUBHA. "STUDIES ON BIOACTIVE NANOCOMPOSITE SERICIN/PVA BLEND FILMS." Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/14623.
Full textAbstract:
The present study focuses on the preparation and characterization of bioactive nanocomposite sericin/ polyvinyl alcohol (PVA) blend films. Films were prepared by blending sericin and PVA by solvent casting method. Different blends were created by varying the concentrations of glutraldehyde (GA), glycerol as plasticizer, closite 30B as bioactive nanoclay and silver nitrate as antimicrobial bioactive material. Films were characterised for mechanical, structural, morphological, thermal, biodegradable and antimicrobial properties. Fourier Transform Infrared Spectroscopy (FTIR) of films revealed that GA chemically cross linked with sericin and PVA. Scanning electron microscopic (SEM) revealed that no phase separation in prepared films. These films show the antimicrobial activity against gram negative bacteria Neisseria. Such biodegradable blended films can be used for smart food packaging material.
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CHEN, YEN-CHENG, and 陳彥錚. "The study of characteristics about conductive thin film through polyvinyl alcohol in associate with silver nitrate." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/91815876315778049652.
Full textAbstract:
碩士國立雲林科技大學
環境與安全衛生工程系
104
This study is produced environmental conductive film by polyvinyl alcohol that has biodegradable, non-toxic and tasteless characteristics. Experiment with different concentrations of polyvinyl alcohol and different methods of silver nitrate compound to the polyvinyl alcohol solution. These methods include: Mixed method, Thermal reduced method, Oxidation reduction method. Let itself does not have the conductive properties of the polyvinyl alcohol into the conductive film. The test through various instruments that include: Four-point probe, UV - visible spectrophotometer, X-ray diffraction analyzer, Field emission scanning electron microscope. Various methods were compared their effect between the film and the conductive. We confirmed that if only add to the silver nitrate solution of polyvinyl alcohol, does not affect the surface roughness of the film, but increase the amount of light transmittance while decrease of silver nitrate. Using a four-point probe analysis the sheet resistance of the film, with the film sheet resistance comparable to conductivity, but will know that add the higher concentration of silver nitrate get better conductivity. Using UV-VIS analysis know the maximum absorption wavelength range of the film, we could concluded that the film is absorbing ultraviolet or visible light. By XRD analysis, the use of diffraction peak angle can determine the type of content contained in the crystalline material type, the more sharp peaks, the better effect crystallization.
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Huang, Chia-wei, and 黃家緯. "THE STUDY OF ELECTROLYTIC COLORING IN SILVER NITRATE SOLUTION AFTER THE SECOND ANODIC TREATMENT OF ALUMINUM SHEET." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/vagr9h.
Full textAbstract:
碩士大同大學
化學工程學系(所)
95
The aluminum materiel can produce plane film with larger pores after the secondary anodic treatment. The application of silver nitrate as the electrolytic solution of the electrolytic coloring has the advantage of obtaining pure black anodic film by applying low coloring voltage, short time and dilute concentration. In this research, effects of using respectively silver nitrate and copper sulfate in the electrolytic solution for the electrolytic coloring after the secondary anodic treatment are investigated and the comparison of the properties of the film after coloring are studied. The results show that by applying silver nitrate as the electrolytic solution at an electrolytic voltage of 15Vac, the lowest L-value can be obtained; besides, a-value and b-value approach to zero, the aluminum oxide film has the effect of being in near to purely black. Both the coloring time and the voltage do not have any effect on the film thickness, whereas, it’s the current density of the anodic treatment that has the effect on the thickness of the film. As for the hardness, the larger the electrolytic coloring time or the larger the electric voltage, the hardness of the aluminum oxide film would be worse. With SEM it is known that larger and more pores are produced from secondary anodic treatment than those from primary anodic treatment, and that large quantity of metal ions precipitates into pores on the surface of the coloring film. As for the reflectivity, it is measured that with the silver nitrate solution for the electrolytic coloring, the reflectivity within the range of 600~700 nm is lower than that with the copper sulfate solution. From the dissolution film test, it is known that stronger structure can be obtained by using silver nitrate in the electrolytic solution. Furthermore, according to the corrosion test, better anticorrosion effect can be obtained by using silver nitrate solution for the electrolytic coloring and that the best anticorrosion effect occurs at the anodic current density of 2A/dm2. Through the secondary anodic treatment at the anodic current density of 2A/dm2, by applying silver nitrate as the electrolytic solution, under the coloring voltage of 15Vac and coloring time of 15 min, these are the best operating conditions to obtain a black film with △E value of 9.60, L-value of 9.56, a-value of 0.83, b-value of -0.09, and the lowest reflection of 5.55% within the visible light of 580 nm. Therefore, the best absorption effect is obtained.
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Ndebele, Nkosinobubelo. "Assessment of the use of ceramic water filters with silver nitrate as point-of-use water treatment devices in Dertig, North West Province, South Africa." Diss., 2020. http://hdl.handle.net/11602/1621.
Full textAbstract:
MESHWRDepartment of Hydrology and Water Resources
Water borne diseases due to inadequate and unsafe drinking water is a global challenge that has led to a significant number of deaths and illnesses reported annually. These diseases are prevalent in less-developed countries, especially in rural areas where there is shortage of basic infrastructure and inadequate funds for piped water systems in individual households. Community members are forced to resort to collecting water from communal water points and later storing the water in containers for daily use. Recontamination of microbiologically safe drinking water during and after collection from the water source has been recognised as a problem; hence treating water at household level is one way to provide potable water for affected communities. The microbiological quality of household water may be improved by using point-of-use treatment technologies such as chemical disinfection, solar disinfection and ceramic water filters. Some of these technologies are expensive, less effective and difficult to implement in rural communities. This research thus focused on ceramic water filters and finding an appropriate method for silver application so as to produce filters that are effective in both the provision of clean drinking water and the release of silver levels that are safe for human consumption. An assessment of the efficiency of ceramic water filters made with silver nitrate as point-of -use water treatment device in Dertig Village, North West Province, South Africa was carried out. During production of filters made with silver nitrate, the filters undergo firing in an electric kiln and ionic silver is reduced to metallic nanopatches dispersed throughout the porous ceramic media. Both filters made with silver nitrate and conventional silver nanoparticles impregnated ceramic water filters were manufactured at the PureMadi Dertig Ceramic Filter Facility, South Africa. Resulting filters were evaluated and quantified for total coliform and E. coli removal as well as silver concentration in the effluent. Ceramic water filters made with silver nitrate had a high removal efficiency for total coliforms (94.7%) and E. coli (99.3%). A comparison of the performance of filters made with silver nitrate and silver nanoparticles in the provision of potable water was carried out and results showed that the different filters had similar levels of total coliform and E. coli removal, although the silver nitrate filters produced the highest average removal of 97.23% while silver nanoparticles filters produced the lowest average removal of 85.43%. Reasonable silver levels were obtained in effluent from all filters. Average effluent silver levels were 0.07±0.04mg/L, 0.6±1.10 mg/L and 0.8±1.0mg/L for 1 g, 2 g and silver nanoparticle filters, respectively (below the EPA and WHO standard of 100 mg/L). Because silver nitrate filters resulted in the lowest effluent silver concentrations, this could potentially increase the effective life span of the filter. A cost analysis of the process proved that it was cheaper to produce ceramic water filters using silver nitrate as the chemical can be purchased locally and also eliminates labour related costs. Thus, filters made using silver nitrate could potentially improve performance, reduce production costs, and increase safety of production for workers. The results obtained from this study will be applied to improve the ceramic filtration technology as point-of-use water treatment device in an effort to reduce health problems associated with microbial contamination of water stored at household level.
NRF
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Chou, Hsin-Hung, and 周信宏. "Application of Silver Nitrate Water-based Solution and Inkjet Printing in the Fabrication of 1-D and 2-D Electronically Conductive Structures." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/80898959777983441248.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系碩博士班
96
Over the past ten years, it is in demand for the microelectronics industry to raising their manufacturing efficiency and refining the developments of the elemental electronics components, hence the many attentions given to the direct writing inkjet printing technologies. This technique could effectively improve the efficiency of conventional photolithographic process, mask consuming, and low resolution of screen printing technology. Materials can be deposited only at the desired locations using computer aided controls to enable convenient operation as well as less material wastage, consequently making the process more effective and efficient. Moreover, using metal precursor solution as the printing materials can avoid the problem of some protecting agent remaining due to incomplete thermal treatment, and it is more suitable for the application of printing conductive structures. Silver nitrate water-based solution of 1 M and 5 M concentrations were employed in this study for observing droplets evolution during ink-jetting and constructing 1-D and 2-D micro-conductive patterns. During droplets observation, stable driving voltage ranges for the 1 M and 5 M solutions were found to be ±22 - ±26 volt and ±25 - ±28 volt respectively; where the resulting average micro-droplets size was about 27 μm for both concentrations. When printing with the 1 M silver nitrate, a continuous and uniform micro-conductive 1-D line pattern could be formed at a substrate temperature of 90℃ and step sizes of 20 μm and 30 μm. However, the conductive thin-films could not be formed successfully due to the low solute concentration. This study has attempted to improve the printing quality of 1 M solution and avoid the instable ejection process by introducing the higher concentration solution. Continuous and uniform micro-conductive lines were produced at substrate temperatures of 25 - 90℃ in step sizes of 20 μm and 30 μm; the average width of lines were about 76.1 - 99.9 μm. The 2-D conductive thin-films were printed at a substrate temperature of 25℃ and step size of 10 μm measured a best specific resistance at densest spaces to be about 1.9 x 10-6 Ω•cm. In addition, other special patterns were printed in this study to show the infinite potential for real life applications.
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Gomes, Sara Filipa Pereira. "Aplicações biomédicas do cério." Master's thesis, 2019. http://hdl.handle.net/10284/8709.
Full textAbstract:
O cério é um dos 15 elementos químicos que compõem o grupo dos lantanídeos da tabela periódica. Na natureza, é considerado o metal mais abundante do seu grupo, de simples purificação e o segundo mais leve dos lantanídeos. Estas e outras características suscitaram interesse a diversas indústrias que começaram a explorar as suas propriedades.
Ao longo dos anos, o cério tem-se tornado um elemento muito promissor nas áreas da biologia e da medicina.
O nitrato de cério tem exibido uma significativa capacidade de inibir o crescimento de certos microrganismos, e desta forma, torna-se vantajoso incluí-lo em dispositivos médicos para a prevenção de infeções provocadas por cateteres. Além disso, este sal, também está disponível como adjuvante ao creme sulfadiazina de prata para o tratamento tópico de queimaduras extensas, necroses complicadas e úlceras venosas.
O iodeto de cério tem sido amplamente estudado com o intuito de induzir o encolhimento de tumores.
A aplicação biológica de nanopartículas de óxido de cério começou a ser pesquisada no início do século XXI, devido ao seu carácter antioxidante.
O presente trabalho é elaborado com o recurso a diversas vias de informação, e assim, expõe uma perspetiva histórica baseada em várias evidências científicas relacionadas com as propriedades e aplicações do cério na área da biomedicina.Cerium is one of the 15 chemical elements in the lanthanides group of the periodic table. In nature, it is considered the most abundant metal of his group, the second lightest element of the lanthanides and also the one with a simple purification process. These and other characteristics increase the interest of several industries, which started to explore its proprieties. Over the years, cerium has become a promising element in areas such biology and medicine. As cerium Nitrate has shown a high capacity of inhibit the growth of some microorganisms, it becomes advantageous to include it in the medical devices in order to prevent infections from catheters. Besides that, this salt, is also available as an adjuvant in the silver sulfadiazine cream, used for topical treatment of extensive burns, complicated necrosis and venous ulcers. Cerium iodide has been widely studied to induce the shrinkage of tumors. The biological application of cerium oxide nanoparticles started to be researched in the early years of the XXI century, because of its antioxidant character. This thesis is elaborated with the aid of several information sources, and thus, exposes an historical perspective based in various scientific evidences related to the properties and application of cerium in the biomedicine area.
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Frances, J. "Toxicity of ammonia and nitrite to silver perch (Bidyanus bidyanus)." Thesis, 1999. https://eprints.utas.edu.au/19700/7/Frances_whole_thesis_ex_pub_mat.pdf.
Full textAbstract:
Acutely toxic concentrations (LC\(_{50}\)) of ammonia and nitrite were estimated for juvenile silver perch (Bidyanus bidyanus) during 96h experiments. Additional experiments were conducted for at least 25 days to determine the growth-limiting concentrations of ammonia and nitrite for juvenile silver perch. Furthermore, the effects of exposure to metabolic and reagent ammonia were compared. Gill histopathology was examined in each experiment to determine if changes in gill structure correlated with exposure to toxicant, and whether gill histopathology was a useful indicator of sub-acute intoxication for this species.
The acutely toxic concentration (LC\(_{50}\)) of un-ionised ammonia (UAN) was defined as the concentration at which silver perch lost the ability to orientate. At this point, fish were removed from the experiment, as preliminary research had shown that prolonged exposure beyond this point always led to death. The LC\(_{50}\) was estimated to be 1.2 mg L\(^{-1}\) UAN. The acutely toxic concentration (LC\(_{50}\)) of nitrite was estimated to be 160 mg L\(^{-1}\)NO\(_2\) -N.
Following a 39 day exposure, growth (wet weight gain) of juvenile silver perch was reduced at concentrations of ammonia above 0.36 mg L\(^{-1}\) UAN. There was no significant difference in wet weight gain of control fish or those exposed to 0.02 mg L\(^{-1}\) metabolic ammonia. Growth of silver perch exposed to nitrite at concentrations above 1.43 mg L\(^{-1}\)NO\(_2\) -N for 25 days was reduced.
Following acute exposure to ammonia, there was a significant increase in the percentage of filaments affected by epithelial lifting, but no other significant change in gill histopathology was observed. Acute exposure to nitrite resulted in no significant changes in gill histopathology, although macroscopic observation indicated browning and discolouration of gill tissue at concentrations above 130 mg L\(^{-1}\)NO\(_2\) -N.
After 39 days' exposure to ammonia, there was an increase in the occurrence of epithelial lifting, while no other index of gill histopathology was significantly different. Exposure to metabolic ammonia also increased the percentage of filaments affected by epithelial lifting. Following 25 days' exposure to nitrite, there was a significant difference in the percentage of gill filaments affected by epithelial lifting and hypertrophy.
These results indicate critical concentrations of ammonia and nitrite which will assist in the management of nitrogenous wastes in pond or tank culture of silver perch. Understanding of these concentrations may increase production and reduce the incidence of critical water quality conditions.
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"Ab initio Study of Tantalum Nitride and Silver Adatoms." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.14745.
Full textAbstract:
abstract: In 2022, integrated circuit interconnects will approach 10 nm and the diffusion barrier layers needed to ensure long lasting devices will be at 1 nm. This dimension means the interconnect will be dominated by the interface and it has been shown the interface is currently eroding device performance. The standard interconnect system has three layers - a Copper metal core, a Tantalum Adhesion layer and a Tantalum Nitride Diffusion Barrier Layer. An alternate interconnect schema is a Tantalum Nitride barrier layer and Silver as a metal. The adhesion layer is removed from the system along with changing to an alternate, low resistivity metal. First principles are used to assess the interface of the Silver and Tantalum Nitride. Several stoichiometric 1:1 Tantalum Nitride polymorphs are assessed and it is found that the Fe2P crystal structure is actually the most stable crystal structure which is at odds with the published phase diagram for ambient crystal structure. The surface stability of Fe2P-TaN is assessed and the absorption enthalpy of Silver adatoms is calculated. Finally, the thermodynamic stability of the TaN-Ag interconnect system is assessed.Dissertation/Thesis
Ph.D. Materials Science and Engineering 2012
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Hung, Chun-Chin, and 洪俊欽. "Study on the Acute Toxicity and Tolerance of Nitrite to Juvenile Silver Moony (Monodactylus argenteus)." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/41749650814963882597.
Full textAbstract:
碩士國立東華大學
海洋生物多樣性及演化研究所
101
Silver moony (Monodactylus argenteus) is a common ornamental fish and the development of its early life has been illustrated in detail. Furthermore, breed of silver moony can be operated artificially successfully while the ambient nitrite accumulates easily in intensive culture systems. Accumulation of nitrite causes various damages at different levels. The aim of this study is to evaluate the safe concentration of nitrite for culture and the physiological effects of nitrite on silver moony. Juvenile silver moony bred artificially from embryo stage until 120 days post- hatch were used for 96-h nitrite exposure experiment. The mortality data was recorded and the 96 hours LC50 was calculated by probit-analysis. The LC50-96 h of M. argenteus for nitrite is 54.5 mg/L NO2-N and the suggested concentration for safe rearing is 5.45 mg/L NO2-N. Protein abundance of heat shock protein 70 (HSP70), Na+/K+-ATPase (NKA), proliferating cell nuclear antigen (PCNA) in gills and PCNA in muscle of fish exposed to 0, 25, 50 mg/L NO2-N for 96h was detected by western blotting. HSP70 is significant difference between control and the treatments (P < 0.05), and protein expression of gill NKA is significant difference between 50 mg/L NO2-N and the others (P < 0.05). Moreover, gill and muscle PCNA exhibited the similar protein abundance within all groups (P > 0.05). According to the evidences of molecular responses, exposure to high concentration of nitrite lead to activation of stress responses for cytoprotection and the nitrite also affected on the ionoregulation in M. argenteus. However, the cell cycle related regulation might not be serious affected. This study integrated artificial breeding, analysis of water chemistry and fish physiology to figure out the importance of nitrite monitor in the fish breeding and the potential threat to juvenile silver moony.
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Huang, Sha-li, and 黃莎莉. "Acute toxicity and sublethal effects of nitrite on morphometric indices and physiological responses of juvenile silver moony (Monodactylus argenteus)." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/75973211330392038577.
Full textAbstract:
碩士國立中山大學
生物科學系研究所
103
Silver moony (Monodactylus argenteus) is a common aquarium ornamental species in Taiwan. Due to study on nitrite toxicity in silver moony is lack, an acute toxicity test was carried out by exposing the juvenile fish to 0, 25, 50, 75, 100 and 150 mg/L NO2−N for 96 h. The determined median lethal concentration (96 h - LC50) was 54.5 (42.5-67.9) mg/L NO2−N. The impacts of sublethal nitrite exposure were further investigated. After exposure to 28 mg/L (2 mM) NO2−N for 7 days, decrease of hepasomatic index and increase in plasma glucose levels, osmolality and chloride concentration were observed. Gill Na+/K+-ATPase (NKA) response elevated in silver moony when exposed to sublethal nitrite. In protein quality control (PQC) mechanism, expression of branchial and hepatic heat shock protein (HSP) 90 and 70 up-regulated in response to sublethal nitrite exposure while the levels of ubiquitin-conjugated proteins were constant. The present study showed that sublethal nitrite exposure might be a stressor to affect ionic balance and homeostasis of cellular proteins, and then activation of NKA responses and PQC mechanism was essential for ionoregulatory adjustment and protein stability. This study provided the information to clarify the potential treats of sublethal nitrite toxicity to multi-physiological regulation of seawater teleosts.
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Lin, Hao-Yuan, and 林浩源. "Using Silicon Nitride Thin Film Combined with Silver Nanoparticles to Fabricate Low-reflective Silicon Nanostructure Solar Cells." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/69470150736770141912.
Full textAbstract:
碩士國立聯合大學
材料科學工程學系碩士班
103
Surface plasmon resonance (SPR) effect is suggested to be a popular topics recent studies to improve the performance of solar cells by nanoparticles, and anti-reflective layer on the solar cell applications have also been developed for a long time that it can enhance the efficiency of the solar cell by lower surface reflection and passivation. In this study, we combined these two processes. For nanoparticle fabrication, we sputtered a layer of silver film on the silicon nanopillar solar cell, and then used the inductively coupled plasma (ICP) by controlling the RF power and etching duration to fabricate silver nanoparticles with different sizes. For antireflective coating, we performed the optimization on thickness for the deposition of nitride layer on silicon nanopillar solar cells before and after ICP plasma etching to investigate the effects of both SPR and nitride coating on the performance of nanopillar solar cells. The results show that the nanopillar solar cells with 75 nm antireflection layer have the lowest reflectance (2.3 %) and the highest efficiency (12.65 %). In the following three different structures (nanoparticles on nitride coating, nitride coating on nanoparticle, and sandwich structure) we found that the performance of solar cells can be improved by plasma etching sliver thin film on a 75 nm antireflection layer, in which the surface reflection was reduced from 9.8 % to 1.8 % and the efficiency was increased from 8.05 % to 9.50 %. We believe that the antireflective layer and SPR contribute to these results.
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Tseng, I.-Hsing, and 曾奕軒. "Acute toxicity of nitrite and its sublethal effects on morphometrics, ionoregulation, stress response and energy metabolism in freshwater juvenile silver moony (Monodactylus argenteus)." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/a5jr7b.
Full textAbstract:
碩士國立東華大學
海洋生物多樣性及演化研究所
102
Euryhaline silver moony (Monodactylus argenteus) is a familiar ornamental fish in Taiwan and usually reared in fresh water. Accumulation of nitrite to toxic level would occur in intensive and recirculating aquaculture systems. Therefore, establishment of a safe level of nitrite for rearing aquaculture species is important to avoid the harmful effects. In this regard, the acute tolerance of juvenile silver moony to nitrite and sublethal nitrite exposure were examined to evaluate an appropriate safe criterion. After exposure to different concentrations of nitrite (0,10,15,20 and 25 mg/L NO2--N) for 96h, the mortality was recorded to calculate the median lethal concentration values (LC50). The estimated 96h-LC50 value of nitrite was 10.6 mg/L NO2--N. Furthermore, 0.1, 0.25 and 0.4-fold of the 96h-LC50 value were used to study the sublethal effects on morphometric indices, ionoregulation, stress response and energy metabolism. The results revealed that condition factor and hepatosomatic index were not significantly different in all groups. Moreover, compared to control group, sublethal nitrite exposure at different concentrations resulted in significant increase of protein abundance of gill Na+/K+-ATPase (NKA) and heat shock protein (HSP70) (p < 0.05). In plasma chloride concentration, a significant difference was found between control and 4.24 mg/L NO2--N groups. Liver glycogen content, however, evidently decreased when silver moony were exposed to various nitrite concentration. According to these findings, lower than 1.06 mg/L NO2--N was suggested as a safe level for cultivation of freshwater juvenile silver moony. This study integrated artificial propagation, water chemistry and fish physiology to clarify the potential threats to cultured freshwater fish. To aid in sustainable aquaculture, our findings provided an useful information for artificial cultivation to avoid the severe effects caused by nitrite to improve the aquaculture quality.
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Vyvadil, Jan. "Voltametrické stanovení pentritu pomocí rtuťových a stříbrných amalgamových elektrod." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-342940.
Full textAbstract:
This Diploma Thesis is focused on investigation of the voltammetric behavior of the explosive penthrite (pentaerythritol tetranitrate) (PETN) and on searching for optimum conditions for its determination using differential pulse voltammetry (DPV) at a hanging mercury drop electrode (HMDE) (this part of the Diploma Thesis follows the topic investigated in the author's Bachelor Thesis; in this Diploma Thesis, the results of the Bachelor thesis are applied to the determination of PETN in environmental matrices) and at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and on investigation of voltammetric behavior in real samples (deionized, drinking, and river water). For investigating the behavior of PETN in aqueous-methanolic media on the m-AgSAE, mixtures of Britton-Robinson buffers (BR-buffers) and methanol in various volume ratios were used. In non-aqueous media, methanolic solutions of tetramethylammonium bromide (TMAB), tetrabutylammonium iodide (TBAI), and tetrabutylammonium chloride (TBAC) were used as supporting electrolytes. Firstly, the influence of pH (in the range of 2 - 13) and methanol content (10 - 90 vol. %) on voltammetric responses of PETN was studied. The best response was obtained at each of those pH values at the volume ratio of BR-buffer - methanol of 1:9 or...