Littérature scientifique sur le sujet « Ioni zinco »
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Articles de revues sur le sujet "Ioni zinco"
1
Riss, H., K. Testa, K. Betiatto, Elton Mendes, R. Piletti, Márcio Antônio Fiori et Humberto Gracher Riella. « Biocidal Glasses with High Performance : Comparison of the Antimicrobial Action Obtained by Use of Different Metal Ions ». Materials Science Forum 869 (août 2016) : 963–68. http://dx.doi.org/10.4028/www.scientific.net/msf.869.963.
Texte intégralRésumé :
The development of antimicrobial materials and its use have shown an effective way to reduce the risks posed to human life by fungi, bacteria and other pathogenic microorganisms. This work presents preliminary results about the development of powder biocidal vitreous, applying the ionic exchange process between the sodium ions, present in the glass matrix, and ionic oligodynamic species, present in the ionic exchange medium. The magnitude of the oligodynamic effect was modified with the use of different metal ions, providing significant difference in antimicrobial performance. Three samples were prepared incorporating different ionic metal in its glass matrix during the ionic exchange process, Ag+, Zn2+ and Cu2+. These precursors of cations were used: AgNO3 for the silver ions, ZnSO4 for the zinc ions and Cu (NO3)2 for the cooper ions. Samples were submitted to microbiological analysis – Agar Diffusion Test for Escherichiacoli and Staphylococcusaureus bacterial species, and fungus species Candidaalbicans – and atomic absorption techniques. Results showed higher microbiological magnitude to the silver-glass, followed by the cooper-glass and zinc-glass.
2
Mendes, Elton, Elidio Angioletto, Erlon Mendes, Raquel Ternus, Kelly Regina Betiatto, Riss Heloisa, Karine Testa, Raquel Piletti, Humberto Gracher Riella et Márcio Antônio Fiori. « Kinetics Modelling of the Adsorption Process of Zinc Ions by Glass Microparticles ». Materials Science Forum 930 (septembre 2018) : 556–61. http://dx.doi.org/10.4028/www.scientific.net/msf.930.556.
Texte intégralRésumé :
The oligodynamic property is a lethal effect which some atoms exert over bacteria, fungi and other microorganisms. The oligodynamic property can be promoted by glass microparticles doped by zinc ionic specimens utilizing the ionic exchange processes. This study is aimed at modelling the behavior of adsorption mechanisms of the zinc ions on glass microparticles absorbent, with potential use as antimicrobial material. Aqueous solutions of zinc nitrate were used as the ionic supplying of zinc ions. The amount of zinc adsorbed on the glass was determined by spectroscopy of atomic absorption and with a mass balance analysis for each adsorption conditions. The experimental data were modeled by three Eq.s employed in adsorption kinetics studies: pseudo first order, pseudo second order and Elovich Eq.. The pseudo second order data model presented the better adjust condition. A sample of zinc glass microparticles, prepared at the finest conditions established by the kinetic model of pseudo second order, was submitted to microbiological analysis: agar diffusion test with Pseudomonas aeruginosa and Staphylococcus aureus and with Candida albicans. The glass doped with ionic zinc inhibited the growth of microorganisms in every conducted analysis.
3
Kravchenko, Aleksandr, Denis Dyachenko, Dmitriy Polikarpov et Valeriy Fomichev. « Electrochemical deposition of zinc coatings from the ionic liquid based on choline chloride ». E3S Web of Conferences 121 (2019) : 02008. http://dx.doi.org/10.1051/e3sconf/201912102008.
Texte intégralRésumé :
Galvanic zinc coatings were obtained by using of electrolytes based on ionic liquid choline chloride – urea. Zinc chloride, zinc sulphate and zinc acetate were used as a sources of Zn2+ ions. Influence of zinc salt anion on morphology of deposited coatings shown. Anodic dissolution of obtained zinc coatings investigated in chloride containing aqueous solution.
4
Vieira, Daniela, Jérôme Allard, Kathleen Taylor, Edward J. Harvey et Geraldine Merle. « Zincon-Modified CNTs Electrochemical Tool for Salivary and Urinary Zinc Detection ». Nanomaterials 12, no 24 (13 décembre 2022) : 4431. http://dx.doi.org/10.3390/nano12244431.
Texte intégralRésumé :
Recently, the abnormal level of zinc emerged as a powerful indicator or risk factor for metabolic, endocrine, neurodegenerative and cardiovascular diseases, including cancer. Electrochemical detection has been explored to quantify zinc in a precise, rapid, and non-expensive way; however, most of the current electrochemical systems lack in specificity. In this work we studied a highly selective and sensitive electrochemical method to detect quickly and reliably free zinc ions (Zn2+). The surface of the working electrode was modified with zincon electropolymerized on carbon nanotube (CNT) to enable the binding of zinc in complex body fluids. After being physicochemically characterized, the performances of the zincon-CNT complex was electrochemically assessed. Square Wave Voltammetry (SWV) was used to determine the calibration curve and the linear range of zinc quantification in artificial saliva and urine. This zincon- CNT system could specifically quantify mobile Zn2+ in salivary and urinary matrices with a sensitivity of ~100 ng·mL−1 and a limit of detection (LOD) of ~20 ng·mL−1. Zincon-modified CNT presented as a desirable candidate for the detection and quantification of free zinc in easily body fluids that potentially can become a diagnostic non-invasive testing platform.
5
Pulletikurthi, Giridhar, Maryam Shapouri Ghazvini, Tong Cui, Natalia Borisenko, Timo Carstens, Andriy Borodin et Frank Endres. « Electrodeposition of zinc nanoplates from an ionic liquid composed of 1-butylpyrrolidine and ZnCl2 : electrochemical, in situ AFM and spectroscopic studies ». Dalton Transactions 46, no 2 (2017) : 455–64. http://dx.doi.org/10.1039/c6dt04149c.
Texte intégral
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Abdolmohammad-Zadeh, Hossein, Sima Hassanlouei et Monireh Zamani-Kalajahi. « Preparation of ionic liquid-modified SiO2@Fe3O4nanocomposite as a magnetic sorbent for use in solid-phase extraction of zinc(ii) ions from milk and water samples ». RSC Advances 7, no 38 (2017) : 23293–300. http://dx.doi.org/10.1039/c7ra02126g.
Texte intégral
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Ismail, W. M. I. W., N. S. W. Zulkefeli et M. N. Masri. « A Sight of Zinc Corrosion in Various Alkaline Media ». Journal of Tropical Resources and Sustainable Science (JTRSS) 4, no 2 (13 août 2021) : 95–97. http://dx.doi.org/10.47253/jtrss.v4i2.614.
Texte intégralRésumé :
This review concentrates on corrosion properties that expose to zinc by various alkaline media. The assumption has been advanced that zinc corrodes electrochemically in the first stage of exposition, but the chemical corrosion prevails after a longer time. Different types of electrolyte had been tested on zinc such as sodium chloride, sodium hydroxide and potassium hydroxide. Each of alkaline media can produced corrosion product such as zinc hydroxide chloride, zinc hydroxide carbonate, zinc oxide, and zinc hydroxide. The production of corrosion products is depending on the carbon dioxide content that introduced to the air. Potassium hydroxide is the highest and active alkaline where it contains the highest ionic conductivity potassium ions, K+ after hydronium, H3O+ among the cations and hydroxide, OH ? has the highest ionic conductivity among the anions.
8
Ishida, Tsuneo. « Thrombosis prevention and anti-thrombus formation by zinc (Ⅱ) ions against COVID-19 infection ». Journal of Clinical Case Reports and Studies 3, no 6 (28 juin 2022) : 01–08. http://dx.doi.org/10.31579/2690-8808/114.
Texte intégralRésumé :
Zinc induced COVID-19 thrombosis prevention and anti-thrombus formation have been established by that zinc promotes COVID-19 thrombosis prevention and anti-thrombus formation and zinc ions-induced activated anti-thrombus activity is proceeded to prevent acute ischemic stroke among COVID-19 patients Zinc can reduce neurological outcomes in COVID-19 patients that Zn2+ promotes inflammatory cytokine as a neurodegenerative disorder and the coronaviruses can affect the nervous system through blood circulation, causing neuro-inflammation. Zinc supplementation affects bronchial mucosal epithelial integrity, both under normal and zinc deficient conditions. The other, zinc ions inhibit COVID-19 lung inflammation that zinc ions promote platelet activation function that inhibits pulmonary thromboembo-lism, in which platelets could respond to changes in extracellular and intracellular Zn2+ concentration. Zn2+ plays a major role in the regulation of coagulation that zinc inhibit blood coagulation against COVID-19 infection, in which Zn2+ can modulate platelet and coagulation activation pathways, including fibrin formation that the release of ionic Zn2+ store from secretory granules upon platelet activation contributes to the procoagulant role of Zn2+ in platelet-dependent fibrin formation. Zinc-induced platelet aggregation, low concentrations of ZnSO4 and zinc chelation involve platelet activation and potentiated platelet aggregation. Persistent zinc intake for severe aggravation of COVID-19 has been suggested to be 8–11 mg/day for adults (tolerable upper intake level 40 mg/day) and suggesting that a zinc intake of 30–70 mg/day might aid in the RNA viruses control. Thus, zinc ions can inhibit inflammation, platelet behaviour function, blood coagulation, and neurological thrombus formation during ROS production and excessive oxidative stress against COVID-19 infection. Zn2+ ions-binding with many proteins-molecular mechanism has been clarified that Zn2+ ions may be bound with COVID-19 inflammatory, platelet, coagulation, thrombus proteins by Zn2+ ions-centered tetrahedrally binding protein molecular coordination pattern.
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Ishida, Dr Sci Tsuneo. « Zinc (Ⅱ)-Induced Anti-Thrombus Formation against Severe COVID-19 Infection ». SAR Journal of Medical Case Reports 3, no 2 (7 juin 2022) : 8–16. http://dx.doi.org/10.36346/sarjmcr.2022.v03i02.001.
Texte intégralRésumé :
Zinc(Ⅱ) induced neurological COVID-19 anti-thrombus formation has been established by that zinc induced inhibitive bronchial thrombosis and modulatory pulmonary thromboembolism are attained, causing COVID-19 activated anti-thrombus activity and leading to COVID-19 anti-thrombus formation. Zinc supplementation affected bronchial mucosal epithelial integrity, both under normal and zinc deficient conditions that there was an interaction between the individual zinc status. The other, zinc ions inhibit COVID-19 lung inflammation and promote platelet activation function that inhibits pulmonary thromboembolism, in which platelets could respond to changes in extracellular and intracellular Zn2+ concentration. Zinc-induced platelet aggregation, low concentrations of ZnSO4 and zinc chelation involve platelet activation and potentiated platelet aggregation, in which Zn2+ plays a major role in the regulation of coagulation that zinc inhibit blood coagulation against COVID-19 infection. Zn2+ can modulate platelet and coagulation activation pathways, including fibrin formation that the release of ionic Zn2+ store contributes to the procoagulant role of Zn2+ in platelet-dependent fibrin formation. Further, zinc may reduce neurological resultings in COVID-19 patients that Zn2+ promotes inflammatory cytokine as a neurodegenerative disorder and the coronaviruses can affect the nervous system through blood circulation, causing neuro-inflammation. Zinc ions can inhibit inflammation, platelet behaviour function, and blood coagulation. Hence, zinc ions promote neurological anti-thrombosis formation during ROS production and excessive oxidative stress against COVID-19 infection. Persistent zinc intake for severe aggravation of COVID-19 has been suggested to be 8–11 mg/day for adults (upper intake level 40 mg/day) and suggesting that a zinc intake of 30–70 mg/day might aid in the RNA virus control. Accordingly, Zn2+ ions-binding molecular mechanism has been clarified that Zn2+ ions may be bound with COVID-19 inflammatory, platelet, coagulation, and thrombus various proteins by Zn2+ ions-centered tetrahedrally binding protein molecular coordination pattern.
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Silva, AB, Jorge-E. Rueda-P et Q. Gomes K. « Effect of zirconia in the density and ionic conductivity properties of Bi4V1.8Cu0.1Zn0.1O10.7 compound ». BISTUA REVISTA DE LA FACULTAD DE CIENCIAS BASICAS 13, no 1 (28 juin 2015) : 27. http://dx.doi.org/10.24054/01204211.v1.n1.2015.1665.
Texte intégralRésumé :
Ceramics based bismuth vanadate are conductors of oxygen ions and they are used as solid electrolytes in pressure sensors and fuel cells. These materials operate at temperatures above 700 °C. At high temperatures, the bismuth-vanadium oxide (Bi4V2O11) has a g-phase with a large number of oxygen vacancies that favors the ionic conductivity. The g-phase of the Bi4V2O11 was stabilized at room temperature by partial substitution of vanadium (V5+) ions by cuprum (Cu2+) and zinc (Zn2+) ions to provide high ionic conductivity values between 100 and 400oC. Thus, polycrystalline samples of Bi4V1.8Cu0.1Zn0.1O10.7 were obtained after 4h sintering at 800 °C. Investigations were made about densification process and ionic conductivity related to the effect of addition of the yttria-stabilized zirconia (Zr0.88Y0.12O1.94).
Thèses sur le sujet "Ioni zinco"
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DALLA, POZZA Elisa. « Meccanismi molecolari dell'attività antitumorale associata alla modulazione degli ioni zinco in cellule di adenocarcinoma pancreatico ». Doctoral thesis, Università degli Studi di Verona, 2008. http://hdl.handle.net/11562/337588.
Texte intégralRésumé :
Lo zinco è il secondo metallo maggiormente abbondante nel corpo umano. Questo ione è
essenziale in un’ampia varietà di processi cellulari, in quanto ha un ruolo sia funzionale
agendo da cofattore per più di 300 enzimi, sia strutturale per la stabilizzazione della struttura
terziaria di molte proteine. L’omeostasi dello zinco è un processo cellulare ben regolato
dall’espressione di trasportatori di membrana e di proteine sequestranti zinco. A livello
intracellulare esiste un “pool” labile di zinco, molto dinamico soggetto al flusso ionico ed
influenzato dalla deprivazione e dalla “supplementazione” di questo ione; questo “pool”
labile sembra essere importante per la citoprotezione e la regolazione dell’apoptosi.
Le specie reattive dell’ossigeno (ROS), prodotte costantemente da una varietà di processi
cellulari, causano, a bassi livelli, un aumento della progressione del ciclo cellulare, mentre a
livelli più elevati, un arresto del ciclo cellulare e successivamente apoptosi o necrosi.
L’utilizzo di molecole capaci di indurre stress ossidativo potrebbe essere un’efficace strategia
terapeutica contro il cancro, in quanto, nelle cellule tumorali, aventi un livello basale di ROS
più elevato, un ulteriore aumento di stress ossidativo determinerebbe lo scatenarsi di
fenomeni di morte cellulare che non avverrebbero nelle cellule normali.
In questa tesi sono esposti gli effetti ottenuti in linee cellulari di adenocarcinoma pancreatico
umano trattate con due molecole: la pirrolidina ditiocarbammato (PDTC) [1] e l’N,N,N’,N’-
tetrakis(2-piridilmetil)etilenediammina (TPEN) [2]. Il PDTC, grazie alla sua attività ionofora,
è in grado di aumentare la quantità di zinco intracellulare, a bassi livelli se utilizzato da solo
o a livelli più elevati se utilizzato in associazione con zinco esogeno. L’aumento di zinco
intracellulare è direttamente proporzionale all’aumento di ROS nella cellula e causa fenomeni
diversi a seconda dell’entità dell’incremento. Il PDTC causa l’attivazione di ERK1/2 e
l’induzione di P21, con conseguente blocco della progressione del ciclo cellulare in fase S. Il
trattamento associato PDTC e zinco determina il danneggiamento della membrana
mitocondriale con il rilascio di AIF, che trasloca nel nucleo e causa una forte apoptosi caspasi
indipendente. Il TPEN, grazie alla sua attività chelate, è in grado di diminuire i livelli di zinco
intracellulare, determinando lo scatenarsi di fenomeni indipendenti dallo stress ossidativo. La
sua forte citotossicità è dovuta sia al blocco della progressione del ciclo cellulare in fase G1
sia a morte apoptotica. Il TPEN è in grado di regolare l’espressione di vari geni, in
particolare, per quanto riguarda il ciclo cellulare, aumenta il rapporto tra i livelli di
espressione dei geni inibitori dei complessi ciclina-cdk e i geni delle cicline, mentre per
l’apoptosi, incrementa il rapporto tra i livelli di espressione dei geni mitocondriali apoptotici
e quelli anti-apoptotici. Inoltre, il TPEN determina danno mitocondriale e attivazione delle
caspasi. Sia il PDTC che il TPEN sono risultati essere più efficienti nell’inibizione della
vitalità cellulare delle linee di adenocarcinoma pancreatico rispetto al chemioterapico
standard, la gemcitabina, e inoltre risultano essere poco citotossiche su cellule normali di
fibroblasti primari.not available
2
Granzotto, Alberto. « Role of metal ions dyshomeostasis in neurodegeneration ». Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423606.
Texte intégralRésumé :
In the present study metal ions role in neurodegenerative processes has been investigated. Two major pathways have been developed: 1) metal ions role in β-amyloid (Aβ folding and deposition from in vitro to in vivo; 2) calcium dyshomeostasis in an in vitro model of neurodegeneration.
Firstly, metal ions role (aluminum, copper, iron, zinc) in Aβ folding and deposition was assessed. Aβ misfolding is, in fact, believed to play a critical role in Alzheimer’s disease pathogenesis. Our data confirm that Aβ folding is closely related to the conjugated metal ion, thereby following peculiar metal ion-dependent conformational changes. Strikingly, we report that aluminum, a non physiological metal ion, is the most efficient in “freezing” Aβ in its oligomeric and most toxic state.
Within this framework we investigated the mechanisms underlying Aβ and Aβ-metal conjugates toxicity. To that aim we employed two natural compounds (resveratrol and cholesterol) acting on two different Aβ mechanisms of toxicity: oxidative stress and membrane damage, respectively.
In both cases, in vitro analysis revealed that resveratrol and cholesterol do not influence Aβ and Aβ-metal conjugates folding processes, but are still effective in protecting a neuronal-like cell line against Aβ toxicity. We reported that resveratrol was able to significantly reduce the Aβ-triggered generation of reactive oxygen species, meanwhile physiological concentrations of cholesterol were effective in protecting cellular membrane structure against Aβ (especially Aβ-Al) lipid disrupting activity.
To further assess that differently shaped Aβ-metal conjugates result in different biological responses, we investigated Aβ-Cu and Aβ-Zn role in influencing/altering gene expression profile in a neuronal-like cell line. We found that these two conjugates are effective in modulating expression of transcripts involved in inflammatory processes, oxidative stress, and in apoptotic cell death.
Following these in vitro studies we decided to investigate whether expression of transcripts involved in metal ions homeostasis resulted affected in an in vivo model of the disease, represented by the 3xTg-AD mice. Our data highlight a significant overlapping between the expression profiles of young 3xTg-AD mice compared with aged wild type mice; this finding support the notion that Alzheimer’s disease can be interpreted as a boosted variant of otherwise naturally occurring age-driven changes. In our dataset we found several differentially expressed transcripts involved in calcium homeostasis, a key metal ion for the physiology of the cell.
Secondly, calcium dyshomeostasis in striatal neurons following excitotoxic challenge was assessed. Striatal neurons degeneration is involved in several pathologies showing motor and behavioral sequelae, such as Huntington’s disease (HD). We tried to determine why a subpopulation of striatal neurons results spared in HD striata, showing a peculiar resistance towards excitotoxic challenges. Our data demonstrate that the striking resistance of these cells may be due to boosted scavenging capabilities embedded in such neuronal subpopulation, resulting in lack of ROS generation upon excitotoxic insults.
Collectively, these findings highlight the pivotal role played by metal ions in the development of neurodegenerative disorders. Noteworthy, not only endogenous and biologically relevant metal ions (iron, copper, zinc and calcium) seem involved in the pathogenesis of neurodegenerative disorders, but also exogenous metals (i.e.: aluminum) could have a key and subtle, although less investigated, role in neuronal degenerationIl presente lavoro di tesi si è suddiviso in due filoni principali che hanno come filo conduttore la disomeostasi di ioni metallici nei processi neurodegenerativi. La prima parte riporta lo studio sul ruolo di alcuni ioni metallici (alluminio, ferro, rame e zinco) nel processo di folding della proteina β-amiloide (Aβ), ritenuta uno dei fattori eziopatogenici del morbo di Alzheimer. I dati ottenuti dimostrano come i complessi Aβ-metallo-ione acquistino una peculiare conformazione dipendente dal metallo legato, conferendo così all’Aβ particolari proprietà citotossiche. Tale citotossicità risulta particolarmente evidente per il complesso Aβ-Al che è in grado di aumentare, in maniera significativa, la tossicità data dalla sola Aβ o dalla stessa Aβ coniugata con metalli diversi dall’Al. All’interno di questo quadro sperimentale si è poi cercato di indagare più nel dettaglio i meccanismi con i quali Aβ, e i suoi complessi metallici, esercitassero la loro citotossicità. A questo scopo sono stati impiegati due composti quali il resveratrolo e il colesterolo, che vanno ad agire su due meccanismi che stanno alla base della tossicità dell’Aβ, come lo stress ossidativo e l’alterata fluidità delle membrane cellulari. Nel primo caso, i dati in vitro hanno permesso di dimostrare come, agendo in maniera selettiva sulla produzione di specie reattive dell’ossigeno (ROS) Aβ-mediata, sia possibile ridurre la tossicità di Aβ e dei suoi complessi con metalli redox (rame e ferro) mediante un meccanismo di scavenging dei ROS ad opera del resveratrolo, dalle spiccate proprietà anti-ossidanti e neuro-protettive. A questo punto si è indagata la capacità dei vari complessi Aβ-metalloioni di alterare la struttura di membrane lipidiche attraverso l’uso di modelli di membrane cellulari. In precedenza si era dimostrato come il complesso Aβ-Al fosse l’unico complesso in grado di alterare significativamente la fluidità di layer lipidici. I dati ottenuti ci permettono di affermare che tale capacità è dovuta principalmente alla elevata idrofobicità superficiale del complesso Aβ-Al. Inoltre, agendo sulle membrane cellulari con concentrazioni fisiologiche di colesterolo è stato possibile ridurre l’”irrigidimento” delle membrane (lipidico) conseguente alla presenza di Aβ-Al, e ridurne la citotossicità. Si é quindi approfondito il ruolo geno-tossico dei succitati complessi Aβ-metalloioni andando ad indagare come questi siano in grado di modulare in maniera significativa (e metallo-dipendente) l’espressione genica di numerosi trascritti coinvolti nella patologia di Alzheimer. In particolare, il nostro interesse si è focalizzato sui complessi Aβ-Cu e Aβ-Zn, che si sono rivelati in grado di modulare selettivamente l’espressione di geni coinvolti in processi infiammatori, nello stress ossidativo e nella morte cellulare (apoptosi). Dopo questa serie di studi in vitro si è passati ad indagare l’espressione genica dell’intero genoma umano in un modello in vivo di patologia di Alzheimer. Lo scopo era quello di identificare il network o il pathway d’espressione coinvolti della disomeostasi cationica. I profili d’espressione del modello murino 3xTg-AD sono stati pertanto confrontati con quelli del controllo wild type. In questo contesto, si è scoperta una significativa sovrapposizione dei geni sovra- e sotto-espressi tra topi wild type anziani e topi 3xTg-AD giovani. Questo dato supporta l’idea che il substrato patologico dell’AD possa favorire un processo di invecchiamento precoce. All’interno del gruppo di geni trovati differenzialmente espressi, molti erano coinvolti nell’omeostasi del calcio, ione chiave per la fisiopatologia cellulare. Il secondo filone di ricerca ha riguardato lo studio del ruolo dello ione calcio nell’eccitotossicità dei neuroni dello striato. Tale fenomeno è particolarmente importante in alcune patologie neurodegenerative che hanno come segno caratteristico una progressiva e irreversibile perdita del controllo motorio, come ad esempio il morbo di Huntington. L’interesse si è focalizzato nel determinare il perchè una subpopolazione di neuroni striatali, caratterizzata dalla sovraespressione di nitrico-ossidosintasi, non vada incontro ad apoptosi in seguito a stress eccitotossico. I dati raccolti ci hanno permesso di stabilire che la resistenza di tale sottopopolazione al sovraccarico di calcio è dovuta principalmente ad una potenziata capacità di questi neuroni di detossificarsi rapidamente dalle specie ROS, di origine mitocondriale, specie che si generano durante fenomeni eccitotossici. Conclusione. Nel complesso i dati ottenuti sottolineano una volta di più un ruolo centrale degli ioni metallici nello sviluppo e/o nella progressione di alcune patologie a carattere neurodegenerativo. In particolare è importante notare come, a fianco di alcuni ioni metallici endogeni - che hanno un rilevante ruolo fisiologico (ferro, rame, zinco, calcio) -, anche altri ioni privi (apparentemente) di un ruolo biologico, ma coi quali ci interfacciamo quotidianamente, come ad esempio l’alluminio, sembrino svolgere un ruolo chiave in processi eziopatogenetici legati a fenomeni neurodegenerativi
3
Borba, Carlos Eduardo. « Estudos do proceso de troca ionica do sistema multicomponente cobre-zinco-sodio utilizando a resina Amberlite IR 120 ». [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267139.
Texte intégralRésumé :
Orientadores: Reginaldo Guirardello, Edson Antonio da SilvaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-14T18:58:40Z (GMT). No. of bitstreams: 1 Borba_CarlosEduardo_D.pdf: 1593358 bytes, checksum: 8ae06b7d3dd4c535d777a874b5dab2a6 (MD5) Previous issue date: 2009
Resumo: O aumento da produção industrial tem proporcionado a geração de efluentes aquosos contaminados com íons de metais pesados. Estes devem ser tratados antes de serem descartados no meio ambiente. Colunas de leito fixo podem ser eficientes na remoção de íons de metais pesados de meios aquosos. Para o projeto destes equipamentos são necessárias informações a respeito do equilíbrio do sistema, bem como informações a respeito dos efeitos de transferência de massa no sistema. Os principais objetivos deste trabalho foram a interpretação e obtenção de dados de equilíbrio de troca iônica dos sistemas binários Cu+2 - Na+, Zn+2 - Na+ e Zn+2 - Cu+2 e do sistema ternário Cu+2 - Zn+2 - Na+ e interpretação e obtenção de dados experimentais da dinâmica de troca iônica em coluna de leito fixo. Neste trabalho, foram realizados experimentos para a obtenção de dados de equilíbrio para os sistemas binários e para o sistema ternário. Estes experimentos foram conduzidos em sistema batelada na temperatura de 25°C. Foram também realizados experimentos de troca iônica em coluna de leito fixo para os sistemas binários Cu+2 - Na+ e Zn+2 - Na+ e para o sistema ternário. Em todos os experimentos foi utilizada a resina Amberlite IR 120 como trocador iônico. No tratamento dos dados experimentais de equilíbrio foram utilizadas a isoterma de Langmuir competitiva e a Lei da Ação das Massas (LAM) ideal e não ideal. A utilização da LAM não ideal exigiu o cálculo do coeficiente de atividade das espécies em ambas as fases. Para o cálculo do coeficiente de atividade dos íons na resina foi empregado o modelo de Wilson. Para o cálculo do coeficiente de atividade dos íons em solução foi empregado o modelo de Bromley. Os resultados mostraram que a isoterma de Langmuir competitiva e a LAM ideal representaram satisfatoriamente os dados de equilíbrio dos sistemas binários Cu+2 - Na+ e Zn+2 - Na+. No entanto, não representaram adequadamente o equilíbrio do sistema Zn+2 - Cu+2. A LAM não ideal representou apropriadamente o equilíbrio de todos os sistemas binários. O equilíbrio de troca iônica do sistema ternário foi representado satisfatoriamente pela isoterma de Langmuir competitiva e pela LAM não ideal, a qual envolveu os parâmetros dos sistemas binários para predizer o equilíbrio do sistema ternário. Para representar a dinâmica de troca iônica em coluna de leito fixo foi utilizado um modelo em que foram consideradas como etapas controladoras da transferência de massa a difusão no filme externo e a difusão nas partículas da resina. Neste modelo foi considerado equilíbrio termodinâmico na interface sólido-líquido, o qual foi representado pela isoterma de Langmuir competitiva e pela LAM não ideal. Os resultados mostraram que o modelo representou satisfatoriamente a dinâmica de troca iônica em todos os casos investigados.
Abstract: The increase in industrial production has provided the liquid effluent generation compound by heavy metal ions. These must be treated before being thrown in environment. Fixed bed columns may be efficient in the removal of these ions in aqueous environment. Therefore, to the project of these equipments, information related to the system equilibrium is essential as well as information about the effects of mass transfer in the system. The main goals of this paper were the achievement and interpretation of the equilibrium data related to the ionic exchange of the binary systems Cu+2 - Na+, Zn+2 - Na+ e Zn+2 - Cu+2 and of the ternary system Zn+2 - Cu+2 - Na+, and the achievement and interpretation of the ionic exchange dynamics in these systems in fixed bed column. In this work, experiments were made to obtain equilibrium data, for binary and ternary system. These experiments were made in batch system at the temperature of 25ºC. Experiments in ionic exchange in fixed bed column were made to the binary systems Cu+2 - Na+ , Zn+2 - Na+ and to the ternary system. In all of the experiments were used the resin Amberlite IR 120 as ionic exchanger. In the treatment of experimental equilibrium data, the competitive adsorption isotherm of Langmuir, the Mass Action Law (MAL) ideal and non ideal were used. The utilization of MAL non ideal required the calculus of activity coefficient of species in both phases. For the calculus of the ions activity coefficient in the resin, the Wilson model equation was used. To calculate the activity coefficient of ions in solution, the Bromley model equation was used. The results showed the competitive isotherm of Langmuir and the ideal MAL represented properly the equilibrium data of the binary systems Cu+2 - Na+ e Zn+2 - Na+. However, they hadn't properly represented the equilibrium of the binary system Zn+2 - Cu+2. The non ideal MAL represented properly the equilibrium of all binary systems. The ionic exchange equilibrium of the ternary system was represented properly by the competitive isotherm and non ideal MAL, which used the binary system parameters to predict the ternary system equilibrium. For the representation of the dynamic of ionic Exchange in fixed bed column, was used a model that considered the diffusion in external film, and diffusion on the resin particles as controller steps of mass transfer. In this model was considered thermodynamic equilibrium on the interface solid-liquid represented by the competitive isotherm of Langmuir and by the non ideal MAL. The results showed the model represented properly the dynamic of ionic exchange in all of the cases investigated.
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
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Bouhsira, Emilie Sautet Jean. « Interaction Zinc-Glutamate dans l'hippocampe dorsal de la souris ». [S.l.] : [s.n.], 2007. http://oatao.univ-toulouse.fr/1805/1/debouch_1805.pdf.
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Jiacheng, Wu. « Modelling 3D Zinc Anodes for Efficient Rechargeable Zinc-Ion Batteries ». Thesis, Faculty of Engineering, School of Chemical and Biomolecular Engineering, 2022. https://hdl.handle.net/2123/29538.
Texte intégralRésumé :
Rechargeable Zn ion batteries have emerged as a promising candidate for energy storage owing to
their advantages in low cost and high safety. Nevertheless, Zn anodes face the critical issues of Zn
dendrite formation and undesired side reactions, which significantly limit their cycling stability and
capacity. Constructing 3D Zn anodes with porous substrates has been proven to effectively inhibit
the Zn dendrite growth via the enlarged surface area and homogenized electric field. However, some
important structural parameters, including porosity, pore depth, etc. have been rarely studied for 3D
Zn anodes. Exploring these parameters can provide valuable insights for the future design of 3D Zn
anodes. In this work, previous research on 3D Zn anodes is firstly reviewed and critically compared.
It is found that the current research mainly utilizes Zn anode composites with various 3D substrates
(carbon, metal, Zn alloy), as well as 3D pure Zn structures. Following this, two different Zn anodes
with varying porosity values are proposed and modelled, namely, 3D Zn pillar anode (porosity=0.3,
0.5, 0.7, 0.9) and 3D Zn concentric anode (porosity=0.1, 0.3, 0.5, 0.7). The electric field distributions
of anodes are explored and simulated using Ansys Maxwell numerical analysis. Consequently, it is
found that increasing porosity can disperse electric field distributions over anodes. In particular, the
Zn pillar anode can accommodate Zn ions more effectively owing to its unique and open pillar
channels, whereas the 3D Zn concentric anode can impose a weaker electric field across pores with
its large volume of space. The studies of pore depth propose a low to moderate pore depth for effective
Zn ion transport in 3D Zn anodes. These results pioneer the research on optimizing the performance
of 3D Zn anodes by exploring their structural designs and parameters.
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de, Souza Ana Paula 1975. « Efeito de ions metalicos divalentes sobre a atividade de metaloproteases da matriz secretadas por celulas do tecido gengival ». [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290002.
Texte intégralRésumé :
Orientador: Sergio R. P. LineDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Metaloproteases da matriz (MMPs) representam uma família de enzimas proteolíticas que participam da degradação da matriz extracelular. Estas enzimas são secretadas na forma de pró-enzimas inativas (zimógeno), sendo então ativadas na matriz extracelular por clivagem do pró-peptídeo. Todos os membros desta família apresentam um íon zinco e cálcio ligado ao seu sítio ativo. As MMPs estão envolvidas em fenômenos fisiológicos e patológicos, como o desenvolvimento das glândulas salivares e dos dentes, e na doença periodontal, respectivamente. Diversos íons metálicos divalentes, como zinco e cobre, estão contidos em materiais odontológicos, como o amálgama dental, e a interação entre metais e o meio ambiente oral têm sido assunto em pesquisa odontológica. Deste modo, o objetivo deste trabalho foi estudar o efeito de sais de diversos metais divalentes sobre a atividade de MMPs secretadas por células do tecido gengival. Fragmentos de tecido gengival foram incubados a 37° C por 24 h em DMEM e as enzimas secretadas foram caracterizadas por iminoprecipitação como MMP-2 e MMP-9. Posteriormente, o efeito destes metais sobre a atividade das MMPs foi testado utilizando zimografia de gelatina e também contra a degradação do colágeno tipo I desnaturado in vitro. Metais divalentes, como o zinco e cobre, mostraram potente efeito inibidor sobre a atividade da forma ativa e zimógeno da MMP-2 e MMP-9
Abstract: Matrix Metalloproteinases (MMPs) are a family of proteolytic enzymes that mediates the degradation of extracellular matrix. They are secreted as inactive proenzymes (zymogen), and they are thought to be activated in the tissue by cleavage of the propeptide. All members of this family have zinc and calcium binding to the active site. The MMPs take part in physiologic and pathologic events, as developmental of salivary glands and teeth and periodontal disease, respectively. Several divalent metal íons, as zinc and copper, are contained in dental materiaIs, as dental amalgam, and the interaction between metal íons and the oral environrnent is a major subject in dental research. The aim of this work was to study the effect of several of divalent metaIs on the activity of MMPs secreted by gingival tissue .cells. Gingival explants were cultured at 37° C for 24 h in DMEM and the secreted enzymes were characterized as MMP-2 and MMP-9 by immunoprecipitation. After, the effect of metaIs on the activity of the MMPs was tested using gelatin zymography and also against denatured collagen type I degradation in vitro. Divalente metaIs, as zinc and cupper, inhibited active and zimogen forms of MNrP-2 and MMP-9
Mestrado
Mestre em Biologia e Patologia Buco-Dental
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Zanatta, Camilla dos Santos. « Preparação e caracterização de óxido de zinco nanoestruturado / ». Bauru : [s.n.], 2009. http://hdl.handle.net/11449/88364.
Texte intégralRésumé :
Orientador: Dayse Iara dos SantosBanca: Manuel Henrique Leite
Banca: Alejandra Hortencia Miranda González
Resumo: Materiais nanoestruturados vêm sendo amplamente estudados pela comunidade científica, devido às suas propriedades únicas obtidas com o controle da síntese dos materiais. Por meio do controle experimental, esses materiais podem ser utilizados em numerosas áreas, tais como na eletrônica e na fotônica. Dentre os vários métodos químicos, o processo poliol vem sendo utilizado devido à fácil obtenção de nanopartículas de óxidos e metais na sua forma elementar. O presente trabalho teve como objetivo a síntese do óxido de zinco nanoestruturado por meio do método poliol. Diferentes precursores metálicos, tais como acetato de zinco dihidratado, nitrato de zinco hexahidratado, sulfato de zinco monohidratado e cloreto de zinco anidro e diferentes tempos de permanência da síntese foram utilizados para verificar possíveis interferências dos ânions precursores na síntese e na morfologia do óxido de zinco quando obtido. Os materiais obtidos das sínteses foram caracterizados por difração de raios X (DRX), análises térmicas (TG/DTA), medidas de adsorção de gás nitrogênio, microscopia eletrônica de varredura (MEV), microscopia eletrônica de varredura de alta resolução (MEV-FEG) e cronopotenciometria. Por meio destas técnias mostrou-se a viabilidade da obtenção do óxido de zinco nanoestruturado dd maneira direta a partir do acetato de zinco, através de refluxo em etilenoglicol por 2, 4 e 8 horas seguido de lavagem e centrifugação. A menor nanoestrutura encontrada apresentou partículas com dimensão de aproximadamente 25 nm e formato poliédrico, as quais foram observadas pelo FEG. A técnica de cronopotenciometria, representada por meio das curvas de carga/descarga mostraram que a utilização do compósito contendo o óxido de zinco sintetizado apresenta melhores resultados quando comparados ao uso... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Nanostructered materials have been extensively studied by the scientific community due to their unique properties obtained by controlled synthesis of materials. By means of the control of parameters, this new materials can be used in a number of applications in electronic and photonic technology. Among the several methods to obtain nanoparticles or nanostructured materials, the polyol method has been applied because it shows easy procedures to produce nanostructured oxides and elemental metals. The aim of this work is the synthesis of nanostructured zinc oxide, one of the most multifunctional oxides, by the polyol method. Different precursors salts like zinc acetate dihydrate, zinc nitrate hexahydrate, zinc sulfate monohydrate and zinc chloride anhydrate, as well as several times of reflux, were used to investigate the influence of the precursos anions on the synthesis and on the morphology of the crystals of zinc oxide whenever produced. The obtained powders were characterized by X-ray diffraction (DRX), thermal analyses (TG/DTA), and measurements of 'N IND. 2' gas adsorption, scanning electronic and field emission microscopy (MEV and FEG) and chronopotentiometry. These techniques showed the possibility of producing nanostructured zinc oxide in direct way from the reflux in etylenglycol for 2, 4 and 8 hours, followed by washing and centrifugation. The smallest nanostructure observed by FEG presented around 25 nm polyhedral particles. The chronopotentiometry, present charge/discharge curves showing better results for the electrode made of polimer composite containing ZnO nanoparticles than the obtaining results for the oxide alone. The best results showed reversibility of the lithium-ion cell upon 20 cycles, applying 3 μΑ electric current and showing a charge potential up to 4.2 V.
O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp
Mestre
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Hensley, Mart Patrick. « Zinc Homeostasis in E. coli ». Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1333655875.
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Luo, Ming. « Transition-metal ions in II-VI semiconductors ZnSe and ZnTe / ». Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4630.
Texte intégralRésumé :
Thesis (Ph. D.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xiv, 141 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 135-141).
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Rivas, Charlotte. « Dual-modal imaging agents for zinc ion sensing ». Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/30814.
Texte intégralRésumé :
The area of MRI/optical imaging has received a lot of attention as their combination brings together the high spatial resolution of MRI with the high sensitivity of optical imaging. Changes in pancreatic β-cell mass contribute to the development of both type 1 and type 2 diabetes. Whilst the processes of β-cell loss are fairly well established for type 1, both the extent of the loss and the underlying mechanisms are relatively unknown for type 2. Zinc ions are highly concentrated in the insulin granules that are contained within β-cells. Few robust approaches currently exist to monitor changes in β-cell mass in vivo, and as such, this project aims to develop responsive lanthanide complexes to bind selectively and respond to zinc levels in this target area. The introductory chapter considers the fundamental aspects of molecular imaging, with a particular focus on magnetic resonance and optical imaging, as well as the intrinsic properties of the lanthanide elements, such as magnetism and luminescence. The subsequent results chapters contain more detailed introductions, relevant to the topics covered within the chapter. The synthesis of dual-modal MR/optical probes is described in chapter two. Three rhodamine-based [GdDO3A] complexes are described and their relaxivity and fluorescence properties are established. The Eu3+ and Tb3+ analogues are also studied. Two of the complexes, which show superior water solubilities, are further studied in in vitro and in vivo experiments. One probe displays a fluorescence pH sensitivity that allows for the differentiation of healthy cells from malignant cells due to their difference in pH whilst the other probe displays fluorescence at all pH's. Both probes show accumulation in the mitochondria. Chapter three discusses the synthesis of an MR zinc sensor using a BPEN chelator as the zinc-binding moiety. Showing high selectivity for zinc, this probe is then further functionalised with the rhodamine fluorophore derivative previously described to give a dual- modal MR/fluorescent zinc sensor. This probe only shows an MR response in the presence of zinc. In vitro experiments show the localisation of the probe to differ from the results of the dual-modal probes discussed in chapter two, showing cytosol localisation. Finally, chapter four concerns the synthesis of a fluorescent zinc sensor and its conjugation to a [GdDO3A] scaffold to give a dual-modal MR/optical zinc sensor. This probe displays an improved response to zinc showing increases in both relaxivity and fluorescence. In vitro experiments with both INS1 and HEK cells show the probe to localise in the lysosome and mitochondria respectively.
Livres sur le sujet "Ioni zinco"
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National Institute of Hydrology (India), dir. Adsorption of lead and zinc ions on sediments. Roorkee : National Institute of Hydrology, 1997.
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United States. National Aeronautics and Space Administration., dir. Ion beam sputter deposited zinc telluride films. [Washington, DC] : National Aeronautics and Space Administration, 1985.
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Geological Survey (U.S.), dir. Ion exchange capture of copper, lead, and zinc in acid-rock drainages of Colorado using natural clinoptilolite : Preliminary field studies. [Denver, CO?] : U.S. Geological Survey, 1992.
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C, Amacher Michael, et Intermountain Research Station (Ogden, Utah), dir. Adding sodium hydroxide to study metal removal in a stream affected by acid mine drainage. [Ogden, UT] : U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station, 1993.
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Zinc Ions in Ear, Nose, and Throat Work. Elsevier, 2013. http://dx.doi.org/10.1016/c2013-0-06666-2.
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Friel, A. R. Zinc Ions in Ear, Nose, and Throat Work. Elsevier Science & Technology Books, 2013.
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Postma, James M., J. Leland Hollenberg et Julian Roberts. Identification of Ferric, Aluminum, and Zinc Ions : Separate from Chemistry in the Laboratory 5e. W. H. Freeman, 2000.
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Bhatnagar, Atul P. Analytical preconcentration of metals by uphill transport across supported liquid membranes. 1989.
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Tang, Yougen, Haiyan Wang et Qi Zhang. Aqueous Zinc Ion Batteries : Fundamentals, Materials and Design. Wiley & Sons, Incorporated, John, 2023.
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Tang, Yougen, Haiyan Wang et Qi Zhang. Aqueous Zinc Ion Batteries : Fundamentals,Materials and Design. Wiley & Sons, Limited, John, 2023.
Trouver le texte intégralChapitres de livres sur le sujet "Ioni zinco"
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Maret, Wolfgang. « Zinc and the Zinc Proteome ». Dans Metal Ions in Life Sciences, 479–501. Dordrecht : Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-5561-1_14.
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Maret, Wolfgang. « Regulation of Cellular Zinc Ions and Their Signaling Functions ». Dans Zinc Signaling, 5–22. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-15-0557-7_2.
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Bhattacharya, Pabitra Krishna, et Prakash B. Samnani. « Zinc in Biochemical Systems ». Dans Metal Ions in Biochemistry, 83–102. 2nd edition. | Boca Raton : CRC Press, 2021. | Originally published : Metal ions in biochemistry / P.K. Bhattacharya. 2005. : CRC Press, 2020. http://dx.doi.org/10.1201/9781003108429-4.
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Maret, Wolfgang. « Zinc and Human Disease ». Dans Metal Ions in Life Sciences, 389–414. Dordrecht : Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-7500-8_12.
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Maret, Wolfgang. « Zinc and Zinc Ions in Biological Systems ». Dans Encyclopedia of Metalloproteins, 2396–400. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-1533-6_185.
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Li, Yang V. « Zinc Overload in Stroke ». Dans Metal Ion in Stroke, 167–89. New York, NY : Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4419-9663-3_7.
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Holze, Rudolf. « Ionic conductance of zinc acetate ». Dans Electrochemistry, 1763. Berlin, Heidelberg : Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-49251-2_1580.
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Holze, Rudolf. « Ionic conductance of zinc malonate ». Dans Electrochemistry, 1764. Berlin, Heidelberg : Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-49251-2_1581.
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Holze, Rudolf. « Ionic conductance of zinc bimalonate ». Dans Electrochemistry, 1765. Berlin, Heidelberg : Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-49251-2_1582.
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Holze, Rudolf. « Ionic conductance of zinc oxalate ». Dans Electrochemistry, 1768. Berlin, Heidelberg : Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-49251-2_1585.
Texte intégralActes de conférences sur le sujet "Ioni zinco"
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Lopes Filho, Wilson Roberto, Yago F. Lopes, Lilian T. F. de M. Camargo et Ademir J. Camargo. « Dinâmica Molecular Ab Initio da Complexarão de Íons zinco com a vitamina C em Fase Gasosa ». Dans VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol2020166.
Texte intégralRésumé :
Zinc and vitamin C are essential micronutrients for the conservation of the human body, being essential for the maintenance of the immune system, reducing the risk, severity and duration of infectious diseases. They are taken together as a food supplement, resulting in the improvement of pneumonia and malaria infections. Vitamin C and zinc are also associated with measures of obesity and adiposity. Studies report that vitamin C complexed in zinc promotes adipogenesis and stimulates the generation of insulin-responsive adipocytes. Therefore, since vitamin C together with zinc are fundamental for the body, and that vitamin C complexed with zinc can promote adipogenesis and stimulate the generation of adipocytes responsive to insulin, the study of the interaction between these micronutrients will broaden the understanding of its bioactivity, which may be important in the study of a new use of vitamin C and zinc combined. Thus, it is intended to study the complexation of Vitamin C with the zinc ion using simulations of Molecular Dynamics ab initio. Through the results of the dynamics, it is found that zinc interacted significantly with 3 atoms of vitamin C, thus identifying the formation of a tridentate complex, since the average distances between the metal and these atoms were between 2.176 and 2.261 Å. A decrease in the free Helmholtz energy is perceived as the zinc approaches these atoms, up to a distance of high stability, which corresponds to the average distance of these interactions. It is also evident that the complexation energy is -220,64 Kcal/mol indicating that the complexation is energetically favorable and that the complex formed is stable. Therefore, the results obtained broadened the knowledge about the complexation of zinc ions with vitamin C, which will be of great importance for the understanding of its bioactivity and in the planning of new drugs.
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Renger, Stefan, Sören Alt, Wolfgang Kästner et André Seeliger. « Investigations About Released Debris and Corrosion Products and Their Impact to Head Loss Build Up and Decay Heat Removal Under Water-Chemical PWR-LOCA Conditions ». Dans 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60261.
Texte intégralRésumé :
Investigations about the release, transportation and deposit of fibrous insulation material (FIM), corrosion products as well as resulting compounds and debris mixtures become more important to reactor safety research, when considering long-term behavior of emergency core cooling systems (ECCS) during loss of coolant accidents (LOCA). Debris released by a leakage jet leads to head loss buildups at the sump strainers, the debris filters and the spacers of fuel assemblies. However, these complex processes may influence the decay heat transfer out of the reactor core. A similar but newer scenario implies that the boric acid coolant in pressurized water reactors (PWR) can support corrosion processes at hot-dip galvanized installations, leading to a significant release of ionic zinc into the coolant during the sump recirculation phase. A long-term change of chemical properties of the coolant (e.g. pH, zinc ion concentration) has to be considered in safety analyses. Chemical analyses showed that the solubility of zinc in boric acid coolant is inversely proportional to the coolant temperature. Consequently, zinc ions can be dissolved at lower temperatures in the containment sump. Precipitations of zinc borate (ZBP) are possible at hot spots in the reactor core. The ZBP can be formed as a flocculent disperse phase in the coolant or as solidified layers at hot fuel rod surfaces. Layer spalling could lead to the release of further solid particles into coolant flow inside the reactor core. In several joint research projects between the Zittau/Görlitz University of Applied Sciences (HSZG) and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) investigations on the impact of these processes to the head loss buildup and the heat transfer from core were done at laboratory and semi-technical scaled test facilities. Generic experiments showed the formation of ZBP in heating rod configurations. The ZBP may remain in the core structures or can be transported on debris filter cakes in upstream and downstream components of ECCS and influence the head loss. After this, research addressed the systematical clarification of physico-chemical mechanisms and their influence on thermal-hydraulic-dynamic processes occurring as a consequence of flow induced corrosion effects during LOCA. This paper includes a description of the most important involved test facilities, applied measuring techniques, an overview of boundary conditions considered experimentally and selected results.
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Bhattacharya, Rabi S., P. He, Y. Xu, M. Goorsky, Edmund G. Seebauer, Susan B. Felch, Amitabh Jain et Yevgeniy V. Kondratenko. « Ion Beam Layer Separation of Cadmium Zinc Telluride ». Dans ION IMPLANTATION TECHNOLOGY : 17th International Conference on Ion Implantation Technology. AIP, 2008. http://dx.doi.org/10.1063/1.3033597.
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Oh, Thomas I. « Broadband AR coatings on zinc selenide substrates using ion-assisted deposition ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.tuh5.
Texte intégralRésumé :
A series of five broadband antireflection coatings on zinc selenide substrates was deposited with or without ion-assisted deposition at a substrate temperature of 220°C. Measurement of laser damage threshold for 10.6-µm, 0.1-µs pulses were made on these coatings. Significant improvements have been made in increasing the durability and laser damage threshold of broadband AR coatings by using the ion-assisted deposition of the zinc selenide films. Coatings prepared using this technique consistently passed the environmental tests for adhesion, 24-h salt spray, and 10-day humidity tests specified by MIL-C-675 and MIL-M-13508. The experimental data indicate that the damage threshold can be increased by using the ion-assisted deposition and by optimizing deposition parameters such as temperature and pressure. The absorption was normally reduced by baking the coatings at the temperature of 300°C in air. Baking increased the damage thresholds of some coatings, especially those which initially had noticeably large absorption. Using the ion-assisted deposition, the zinc selenide films were strengthened by increasing packing density and reducing columnar microstructure. Therefore, it is concluded that the ion-assisted deposition of zinc selenide films definitely increases the laser damage threshold of broadband AR coatings on zinc selenide substrates.
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KWAK, A. « Study of the Impact of –NH2 Modification on Adsorptive Properties of Graphene Oxide ». Dans Terotechnology XII. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644902059-23.
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Abstract. Graphene oxide is a nanomaterial of very high adsorption capabilities due to its vast surface area. Moreover, numerous oxygen functional groups present on the surface of graphene oxide enable its modifications to be performed. The authors aimed to create adsorbents based on activated carbon impregnated with amine-modified graphene oxide. The study showed that the amino group functionalisation, both with the use of ethylenediamine (GO-EDA) and using polyaniline (GO-PANI), causes the adsorbent to remove lead, mercury, copper, and iron ions from aqueous solutions very efficiently. Both adsorbents also reduce the cadmium, nickel, zinc, and arsenic ion content, however to a lesser extent but nevertheless still significantly. The two sorbents can be applied in field water treatment to remove specific contaminants.
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Desai, A. V., et M. A. Haque. « Effect of Electromechanical Coupling on the Young’s Modulus of Zinc Oxide Nanowires ». Dans ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/detc2008-49911.
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The Young’s modulus of zinc oxide nanowires was measured to be significantly lower than bulk zinc oxide, which cannot be explained within the framework of existing theories. We propose that the strong electromechanical coupling in piezoelectric materials, such as zinc oxide, influences the measured mechanical properties. The asymmetric wurtzite crystal structure and the ionic nature of the molecular bonding result in internal electric fields during straining of the zinc oxide nanowire, which in turn lead to reduction in the measured modulus. In case of flexural deformation, additional electromechanical coupling is present due to the flexoelectric effect.
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Holcomb, G. R., S. J. Bullard, B. S. Covino, S. D. Cramer, C. B. Cryer et G. E. McGill. « Electrochemical Aging of Thermal Sprayed Zinc Anodes on Concrete ». Dans ITSC 1996, sous la direction de C. C. Berndt. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.itsc1996p0185.
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Abstract Thermal-sprayed zinc anodes are used in impressed current cathodic protection systems for some of Oregon's coastal reinforced concrete bridges. Electrochemical aging of zinc anodes results in physical and chemical changes at the zinc-concrete interface. Concrete surfaces heated prior to thermal-spraying had initial adhesion strengths 80% higher than unheated surfaces. For electrochemical aging greater than 200 kC/m2 (5.2 A-h/ft2), there was no difference in adhesion strengths for zinc on preheated and unheated concrete. Adhesion strengths decreased monotonically after about 400 to 600 kC/m2 (10.4 to 15.6 A-h/ft2) as a result of the reaction zones at the zinc-concrete interface. A zone adjacent to the metallic zinc (and originally part of the zinc coating) was primarily zincite (ZnO), with minor constituents of wulfingite (Zn(OH)2), simonkolleite (Zn5(OH)8Cl2H20), and hydrated zinc hydroxide sulfates (Zn4S04(OH)5xH20). This zone is the locus for cohesive fracture when the zinc coating separates from the concrete during adhesion tests. Zinc ions substitute for calcium in the cement paste adjacent to the coating as the result of secondary mineralization. The initial estimate of the coating service life based on adhesion strength measurements in accelerated impressed current cathodic protection tests is about 27 years.
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Otsuka, M., S. Marunaka, Y. Matsuda, A. Ito, P. Layrolle, H. Naito et N. Ichinose. « Calcium Level-Responsive Zinc Ion Release from Tricalcium Phosphate Containing Zinc (ZnTCP) ». Dans Proceedings of the 12th International Symposium on Ceramics in Medicine. WORLD SCIENTIFIC, 1999. http://dx.doi.org/10.1142/9789814291064_0137.
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Yan, Fei, Amy T. Kan, Chao Yan, Lu Wang, Ya Liu et Mason B. Tomson. « Experimental and Modeling Study on Enhancement of Squeeze Treatment in Sandstone by the Addition of Zinc Ion ». Dans SPE International Oilfield Scale Conference and Exhibition. SPE, 2014. http://dx.doi.org/10.2118/spe-169753-ms.
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Abstract Scale inhibitor squeeze treatment is often used to control mineral scales in the oilfield. However, the performance of scale inhibitor squeeze treatment is sometimes not satisfactory due to low inhibitor retention in the formation and a short squeeze life. It has been previously found that the addition of transition metal ions increased the retention of phosphonate and carboxylate polymeric inhibitor in carbonate formation. In this study, laboratory squeeze experiments were conducted to evaluate squeeze treatment by the addition of metal ions (zinc) in Berea sandstone and oil field core materials. Several scale inhibitors including phosphonate, phosphinopolycarboxylic acid (PPCA), and phosphonated carboxylate polymer were investigated, and these scale inhibitors were mixed with metal ions in the inhibitor pill for squeeze application. Experimental results demonstrated that zinc ions in the inhibitor pills improved retention of scale inhibitors and increased squeeze life significantly. It is proposed that the metal-inhibitor precipitate or complex formed, and the formation of the precipitate/complex enhances the adsorption of scale inhibitor in the mineral matrix. It was also found that chemical composition of the mineral may have an impact on the performance of squeeze treatment, and high concentration of iron may limit the effectiveness of this treatment. The demonstration of metal ions to improve scale inhibitor squeeze will have significant implications on scale control in the oilfield.
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Desai, A. V., et M. A. Haque. « Effect of Strain Induced Charge Redistribution on Young’s Modulus of Zinc Oxide Nanowires ». Dans ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41210.
Texte intégralRésumé :
As the size of material decreases to nanoscale, fundamental material properties such as Young’s modulus are different from bulk values. In this paper, we propose a new mechanism to explain the difference in experimentally observed Young’s modulus values between zinc oxide nanowires and bulk zinc oxide. As a binary compound material (such as zinc oxide) is strained, the effective charge on the ionic constituents of the material changes (in this case zinc and oxygen). The strain induced charge redistribution effect is more significant in nanostructures (such as nanowires) because of their higher fracture strains compared to their bulk counterparts. Since the Young’s modulus of a material is related to the effective charge, we observe differences in modulus values between nanowires and their bulk equivalent. The strain induced charge redistribution phenomenon can also be used to explain variation in modulus values between bulk and nanoscale for other single crystal piezoelectric materials such as silicon carbide.
Rapports d'organisations sur le sujet "Ioni zinco"
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Li, H., J. Q. Chambers et D. T. Hobbs. Electroreduction of nitrate ions in concentrated sodium hydroxide solutions at lead, zinc, nickel, and phthalocyanine-modified electrodes. Office of Scientific and Technical Information (OSTI), décembre 1987. http://dx.doi.org/10.2172/665993.
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Oji, L. N. Ion Exchange Conceptual Design for Treating Seven Technical Area Sumps with Elevated Levels of Copper and Zinc. Office of Scientific and Technical Information (OSTI), février 1999. http://dx.doi.org/10.2172/4814.
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