Дисертації з теми "Hemihydrate de sulfate de calcium"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Hemihydrate de sulfate de calcium".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Chan, Kwok-chu Timmy. "Calcium sulphate hemihydrate effect of humidity in storage /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21129526.
Повний текст джерелаLing, Yuanbing 1970. "Direct preparation of alpha-calcium sulfate hemihydrate from sulfuric acid." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84283.
Повний текст джерелаFor the standard preparation procedure of adding lime into hot sulfuric acid, alpha-hemihydrate grows in the c-axis direction much more rapidly than in other directions ending in the form of fine needle crystals. Also, independent of the shape of the seed particles, the resultant crystals of hemihydrate are needle-shaped, which suggests a "dissolution-recrystallization" mechanism. Upon prolonged equilibration in their acid-preparation solution hemihydrate needle-shape crystals become fibrous and eventually convert to anhydrite. It is believed that uptake of SO42- instead of Ca2+ is the rate-determining step in the hemihydrate crystallization process. The hot SO42--rich environment rendered most of the additives (particularly organic) tried ineffective. Trivalent cations such as Fe3+ and Al3+, are the only ones found to modify the crystal morphology from needle-shape to small "grain" type morphology.
Slow addition of H2SO4 solution to slaked lime - reverse procedure was found to favor the production of alpha-hemihydrate with column-shaped as opposed to needle-shaped crystal morphology within otherwise the same operating window, 0.6--1.1M H2SO4. Preliminary assessment of the properties of the alpha-hemihydrate materials synthesized in this work showed them to compare satisfactorily with other materials produced by conversion of dihydrate to hemihydrate.
Nilles, Vera [Verfasser]. "Insights into the Retarding Mechanism of Linear Sodium Polyphosphates on the Hydration of α-Calcium Sulfate Hemihydrate / Vera Nilles". München : Verlag Dr. Hut, 2012. http://d-nb.info/1021072931/34.
Повний текст джерелаAlvarez-Dalama, Alina 1960. "CALCIUM-SULFITE HEMIHYDRATE CRYSTALLIZATION IN LIQUORS WITH HIGH TOTAL DISSOLVED SOLIDS (GROWTH, SIZE DISTRIBUTION, NUCLEATION, HABIT)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275528.
Повний текст джерелаRong, Yi. "Formation du sulfate de calcium hémihydrate de type α à partir de gypse par un procédé de dissolution-cristallisation : étude cinétique expérimentale et modélisation". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM070/document.
Повний текст джерелаIn mineral or pharmaceutical industry, many transformations of solids in solution (polymorphic or not), take place by the dissolution of the first solid and the crystallization of the second solid. Instead of the traditional drying process, the conversion of gypsum (calcium sulfate dihydrate) to alpha-bassanite (calcium sulphate hemihydrate) can be carried out in aqueous solution by increasing the temperature sufficiently. At this moment, the gypsum becomes more soluble in water than the hemihydrate, which then has the possibility to crystallize. An apparatus and an original procedure have been designed to investigate the sensitivity of the kinetics of transformation and the characteristics of the hemihydrate crystals obtained under its operating conditions. In fact, this dissolution-recrystallization route allows to control the aspect ratio of the hemihydrate crystals, and even their average size and size dispersion, by the choice of its physicochemical conditions such as temperature, pH, use of additives, and seeding the solution with the appropriate hemihydrate particles. Image analysis techniques are developed to identify the aspect ratio of the particles.A kinetic model taking into account the dissolution of gypsum, the nucleation and the growth of calcium sulphate hemihydrate and their equilibrium in aqueous phase and solubility had been developed and the equations of this model are solved with the help of MATLAB software. Coupled with a numerical optimization method, this resolution under MATLAB makes it possible to examine the validity of the assumptions on the selected processes and to identify their kinetic parameters
SIDQUI, MUSTAPHA. "Etude du comportement des osteoblastes et des osteoclastes de rat en culture au contact de biomateriaux a usage odontologique." Paris 7, 1998. http://www.theses.fr/1998PA07GA01.
Повний текст джерела陳國柱 and Kwok-chu Timmy Chan. "Calcium sulphate hemihydrate: effect of humidity in storage." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B21129526.
Повний текст джерелаGirgin, Seref. "Crystallization of alpha-calcium sulphate hemihydrate by aqueous reaction of calcium chloride with sulphuric acid." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102980.
Повний текст джерелаIn the reactive crystallization study H2SO4 was the limiting reactant added to the CaCl2 solution up to 0.8 SO 4/Ca molar ratio. The nucleation and growth stages were successfully separated via supersaturation control achieved by regulated addition of the limiting reactant in multiple steps. This separation permitted the growth of the homogeneously nucleated crystals within the metastable zone to needle-shaped hexagonal crystals (acicular habit). Upon recycling (seeding) of the product further growth was achieved, producing crystals with 80 mum - volume based mean crystal diameter- or 100-120 mum length and 10-15 mum diameter. Growth of the seed crystals appeared to follow an agglomeration mechanism. However, in the presence of foreign metal cations (in particular divalent, Mg 2+, Fe2+, Ni2+ and trivalent, Al 3+, Fe3+) crystal growth was severely retarded via their apparent adsorption. Some of the metal cations, namely Na+, Ni2+, Al3+ were found to incorporate into the hemihydrate crystal structure to a variable extent from 0.3g/t for Na to 7g/t for Ni and 11g/t for Al. The chloride uptake was less than 10 ppm.
Pierre, Alexandre. "Rhéologie de suspensions concentrées de sulfate de calcium." Phd thesis, INSA de Rennes, 2013. http://tel.archives-ouvertes.fr/tel-00910334.
Повний текст джерелаKuthadi, Sandeep Kumar. "Laboratory Scale Study of Calcium Sulfate Hydration Forms." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1467.
Повний текст джерелаGovender, Desania Raquel. "The burn rate of calcium sulfate dihydrate-aluminium thermites." Diss., University of Pretoria, 2018. http://hdl.handle.net/2263/66196.
Повний текст джерелаDissertation (MEng)--University of Pretoria, 2018.
Chemical Engineering
MEng
Unrestricted
Wang, Yuan School of Chemical Engineering & Industrial Chemistry UNSW. "Composite fouling of calcium sulfate and calcium carbonate in a dynamic seawater reverse osmosis unit." Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/26007.
Повний текст джерелаHorne, Kerry Allison. "The refining of calcium using a sulfate reducing bacterial system." Thesis, Rhodes University, 2001. http://hdl.handle.net/10962/d1003974.
Повний текст джерелаOppici, Maria A. "Sodium sulfate hot corrosion of silicon carbide fiber-reinforced calcium aluminosilicate." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA297663.
Повний текст джерелаOrellana, Bryan R. "BIOERODIBLE CALCIUM SULFATE BONE GRAFTING SUBSTITUTES WITH TAILORED DRUG DELIVERY CAPABILITIES." UKnowledge, 2014. http://uknowledge.uky.edu/cbme_etds/18.
Повний текст джерелаLi, Zhibao 1962. "Measurement and chemical modeling of calcium sulfate solubilities in concentrated chloride media." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102677.
Повний текст джерелаFeldmann, Thomas. "Crystallization kinetic investigations of calcium sulfate phases in aqueous CaCl2-HCl solutions." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121477.
Повний текст джерелаLa cinétique et la qualité cristalline d'un nouveau système de cristallisation réactive menant à la formation des phases de sulfate de calcium avec la génération simultanée de l'acide chlorhydrique (un acide fort, jusqu'à 9 M) ont été étudiées. Les études entreprises dans cette recherche sont reliées à un nouveau procédé de régénération de l'acide chlorhydrique présentement en développement pour des applications industrielles dans des opérations hydrométallurgiques des métaux non-ferreux. Cette thèse considère les aspects suivants: (a) la cinétique de cristallisation du sulfate de calcium α-hémihydraté (HH); (b) la cinétique des transitions de phase du sulfate de calcium; (c) les effets des impuretés sur la cristallisation réactive des phases du sulfate de calcium; et (d) les effets des modificateurs de cristaux dans la qualité cristalline du sulfate de calcium. Concernant (a), les taux de croissance des cristaux de sulfate de calcium α-hémihydraté, normalisés selon l'aire de surface, ont été déterminés dans deux types de solutions–à haute concentration en CaCl2 (HCl 1.4 M, CaCl2 2.8 M) et à haute concentration en HCl (HCl 5.6 M, CaCl2 0.7 M)–avec un réacteur semi-continu opéré à sursaturation constante dans une série de températures allant de 70°C jusqu'à 95°C. Il a été montré que le taux de croissance dépend uniquement du débit d'introduction des réactifs Ca2+ et SO42-, et qu'il obéit à la deuxième loi de cristallisation de von Weimarn reliant la taille du cristal avec le niveau de sursaturation. De plus, il a été trouvé que la largeur de la distribution de tailles des particules diminue lorsque le taux de croissance du cristal augmente. En (b), une étude sur la cinétique des transitions de phase du sulfate de calcium dihydraté (DH) et du HH a été réalisée dans des réacteurs discontinus sur un intervalle de concentrations de CaCl2 (de 0.25 M jusqu'à 4.97 M), de HCl (de 0 M jusqu'à 9.43 M), et de températures (de 40°C jusqu'à 90°C) incluant l'effet de la nucléation. Deux mécanismes de transition ont été identifiés: un mécanisme de dissolution-précipitation pour la transition du DH vers le HH, et un mécanisme à réaction topotactique pour la transformation du HH en AH. Une réduction de la durée de vie des phases métastables, DH et HH, a été trouvée lorsque la température a été augmentée et l'activité avec de l'eau a été réduite. En (c), les effets d'une série d'impuretés cationiques et anioniques (K+,Mg2+,Sr2+,Ba2+,Al3+,Fe2+,Fe3+,La3+,Y3+, F- (fluorure), PO43- (phosphate)) sur la cristallisation réactive des phases du sulfate de calcium dans des solutions à haute concentration de CaCl2 (1.82 M) et HCl (6.29 M) ont été déterminés à 40°C et à 80°C pour le DH et le HH respectivement. Parmi toutes les impuretés, l'incorporation de strontium dans le DH et le HH s'est montrée la plus élevée, par substitution du Ca2+ à cause de la similarité de leurs rayons ioniques. L'autre impureté qui a eu un effet négatif lorsqu'elle a été incorporée de façon significative durant la croissance du cristal est le phosphate. De plus, ces deux impuretés ont engendré une transition de phase du DH vers le HH lorsque certains niveaux de concentration ont été dépassés. Finalement en (d), les effets d'une vaste plage de modificateurs de la morphologie de cristaux ont été examinés dans des solutions de CaCl2-HCl à différentes concentrations. Les additifs les plus actifs ont été le bromure de cétyltriméthylammonium (CTAB), l'acide polyacrylique et l'acide polyvinyle sulfonique. L'utilisation du CTAB a favorisé la formation des plaques épaisses de cristaux, ce qui est d'intérêt industriel, alors que l'acide polyacrylique a engendré la formation des cristaux minces et allongés. Ce comportement avec l'acide polyacrylique, s'explique par la prédilection pour certains plans cristallographiques lors de l'adsorption. L'utilisation de l'acide polyvinyle sulfonique a nui à la nucléation et à la croissance des cristaux, ce qui s'explique par sa structure polymérique.
Zangaro, Renato Amaro. "Étude et application du sulfate de calcium en cartographie de radiation ionisante." Montpellier 2, 1988. http://www.theses.fr/1988MON20114.
Повний текст джерелаZangaro, Renato Amaro. "Etude et application du sulfate de calcium en cartographie de radiation ionisante." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376192249.
Повний текст джерелаKedziora, Charlotte. "Propriétés d’usage et mécanismes d’hydratation du système ternaire [Ciment Alumineux – Sulfate de Calcium – Laitier de Haut Fourneau] à haute teneur en sulfate de calcium : De l’approche expérimentale à la modélisation." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0047/document.
Повний текст джерелаThe potential of activation of a Ground Granulated Blast Furnace Slag has been evaluated into a ternary system comprising of a Calcium Sulfate as major component and a Calcium Aluminate Cement. This system is not well known and the main goal of this study is to determine its main advantages and limitations. From the usage properties point of view, fast setting and initial strengths are governed by the ettringitic binder. Then, and only if the dehydration is avoided, slag reacts. In this case, slag contributes to the increase of mechanical performances at medium and long terms and to limit the expansion under water. From an understanding point of view, the original experimental approach reveals the potential of the slag. It is based on a comparison of performances with different types of curing methods. The potential of hydration of the slag is amplified when the system is dehydrated during a few days and then rehydrated. However, slag contribution is complex to establish because analytical methods to follow-up slag consumption (such as X-ray Diffraction and Differential Scanning Calorimetry analysis) are not well adapted. So, to understand the hydration mechanisms, indirect approaches are used. Semi-quantitative methods by X-ray Diffraction to follow-up the mayenite, calcium sulfate, syngenite and ettringite, ThermoGravimetric Analysis to measure degree of hydration and Mercury Intrusion Porosimetry to identify microstructural changes have been carried. The most important difficulty concerns the identification and quantification of amorphous phases such as slag, C-S-H and AH3. That is why a modelling approach is necessary to understand the role of each compound in the ternary mixture and in particular the obvious contribution of slag during rehydration test. This modelling approach increases knowledge of the physical and chemical phenomena in this ternary binder. It is useful to explain the observed macroscopic properties such as strength and helps to determine the kinetics of hydration in porous environment. Even if this model is still under development, it has allowed identifying the sequences of hydration (ettringitic binder reacts at very initial time, then anhydrite transforms into gypsum and slag reacts at long term) and confirms therefore that the reaction of slag is slow
Pereira, Rodrigo de Paula [UNESP]. "A atividade antimicrobiana de agentes desinfetantes incorporados ao gesso tipo IV." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/98032.
Повний текст джерелаCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Vários protocolos de desinfecção podem ser usados para romper a cadeia de infecção cruzada entre o consultório odontológico e o laboratório de prótese. A inclusão de agentes antimicrobianos à composição do gesso ou a manipulação do gesso com soluções desinfetantes podem ser usados com esta finalidade. O propósito deste estudo foi avaliar a atividade antimicrobiana de dois agentes desinfetantes (digluconato de clorexidina 2% e cloridrato de clorexidina 98%) incorporados ao gesso IV (FujiRock - GC Europe, Leuven, Bélgica) durante sua manipulação. No teste microbiológico de difusão em Agar foram uti l izados os seguintes microorganismos: Escherichia coli, Staphylococcus aureus, Bacilus subtilis e Candida albicans. Amostras com 5 mm de diâmetro e 3 mm de espessura foram separadas em quatro grupos: 1) gesso manipulado com água destilada esterilizada (controle positivo); 2) discos de papel embebidos com solução de digluconato de clorexidina 2% (controle negativo); 3) gesso manipulado com solução de digluconato de clorexidina 2%; 4) gesso com a incorporação de cloridrato de clorexidina 98% em pó, na proporção de 1% da massa do gesso, e manipulado com água destilada esterilizada. Após 1 hora e 24 horas do vazamento do gesso, as amostras foram posicionadas em placas de Petri com meios de cul tura específicos inoculados com as suspensões microbianas. A atividade antimicrobiana dos desinfetantes foi avaliada pelo diâmetro médio dos halos de inibição do crescimento microbiano. Os valores foram analisados pela ANOVA Aninhada (p<0,05) e teste de Tukey para comparações específicas. Os resultados encontrados demonstraram que os agentes desinfetantes analisados apresentaram atividade antimicrobiana quando misturados ao gesso, com exceção para Candida albicans, na qual não houve efeito da solução de clorexidina nos dois períodos de análise...
Many protocols for disinfection procedures can be used to break the chain of cross-contamination between dental office and dental laboratory. The inclusion of antimicrobial agent to the composition of gypsum or the manipulat ion of gypsum with disinfectant substances can be used to that aim. The purpose of this study was to evaluate the antimicrobial activity of two disinfectant agents (2% chlorhexidine digluconate and 98% chlorhexidine hydrochloride) incorporated into type IV dental stone (FujiRock - GC Europe, Leuven, Belgium) at the time of mixing. The microbiological test used was the Agar diffusion test to the following microorganisms: Escherichia coli, Staphylococcus aureus, Bacilus subtilis and Candida albicans. Samples of 5 mm in diameter and 3 mm in length were separated in four groups: 1) dental stone mixed wi th steri le distilled water (positive control); 2) paper disk soaked wi th solution of 2% chlorhexidine digluconate (negative control); 3) dental stone mixed with solution of 2% chlorhexidine digluconate; 4) dental stone wi th incorporation of chlorhexidine hydrochloride 98% powder, in proportion of 1% of the dental stone mass, and mixed with sterile distilled water. The samples were placed, 1 hour and 24 hours after pouring of dental stone, in Petri plates with specific cul ture medium wich were inoculated with the microbial suspensions. The antimicrobial activity of disinfectant was evaluated by the average diameter of microbial growth inhibi tion zones. The data were analyzed with a Nested ANOVA (p<0,05) and Tukey test for specific comparisons. The disinfectant agents analyzed demonstrated antimicrobial effect against microorganisms used in this study, in exception to Candida albicans, against wich there was not effect from chlorhexidine digluconate at two periods of analysis. Significant difference between disinfectantes were found to all microrganisms... (Complete abstract click electronic access below)
Marraha, Mohamed. "Synthèse et étude physico-chimique des phosphosulfates de calcium de structure [Béta] Ca3(PO4)2." Toulouse, INPT, 1989. http://www.theses.fr/1989INPT025G.
Повний текст джерелаNguyen, Tien Dung. "Apport des aluminates de calcium vis-à-vis de la résistance à l'eau des sulfates de calcium hydratés." Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0002.
Повний текст джерелаCalcium sulphate materials are economical and ecological. But their use in the construction is quite limited because of their sensibility to water. The capacity of aluminate cement (CAC) to decrease the water sensibility of calcium sulphate and the mechanisms of insensibilisation were investigated. Waterproofing of gypsum base materials was carried out by addition of small amounts of aluminate cement (≤ 30%). Different nature of calcium sulphates : gypsum, hemihydrate α and β, synthetic anhydrite was studied. The study of mechanisms of insensibilisation to water of calcium sulphate by adding cement Fondu, with different analysis of microstructure : IR, DRX, ATD-TG, MEB, revealed two approaches : formation of ettringite insoluble and formation of gel AH3 that stick soluble grains of calcium sulphate. The nature of phases of aluminate cement has influences on the mechanical properties, sensibility to water and durability of mixtures [calcium sulphate / CAC]. The studies of mixtures [synthetic anhydrite / slag / CAC] offer interesting perspectives for the development of binders with low imprint CO2
Ait, Kettout Ahcéne. "Influence de la nature des sulfates de calcium sur l'hydratation d'un ciment en présence d'adjuvants." Toulouse 3, 1989. http://www.theses.fr/1989TOU30232.
Повний текст джерелаNewton, Peter J. "Sodium sulfate corrosion of silicon carbide fiber-reinforced calcium aluminosilicate glass-ceramic matrix composites." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283703.
Повний текст джерелаAranda, Berenger. "Réactivité et durabilité à base de sulfate de calcium et de liants minéraux classiques." Rennes, INSA, 2012. http://www.theses.fr/2012ISAR0001.
Повний текст джерелаKerysten® is a calcium sulfate binder product by “flash calcination”. The binder is originally made of γ-anhydrite (CaSO4) and hemihydrate (CaSO4. 0,5H2O). These two phases form a complex grain which leads to one stable state and two metastable states. To compare the settings of the Kerysten® and a plaster of Paris, we have synthesized both materials with the same quantity of water and the same quantity of retarding admixture. The Kerysten® reacts faster with water than the plaster of Paris. The mechanical properties of the Kerysten® are more important than these of the plaster of Paris. These differences are due to the complex grains of the Kerysten®. We have hydrated a mixture of 70% of Kerysten® and 30% of Portland cement. During the setting, gypsum skeleton has been formed first. This phase has delayed the hydration of the cementitious phases which have precipitated into the porous system. In this material, Kerysten® improves the hardness of the material at early stage and cementitious precipitates improve mechanical strengths. We have studied mortars made with different ratios of Kerysten® and Portland cement. Mortars with small quantities of Portland cement between 5% and 20% have mechanical strengths as important as these of a 100% Portland cement mortar. Prismatic specimens have been made of the mixture of 70% of Kerysten® and 30% of Portland cement. Their durability has been studied under different conditions of chemical attacks: prismatic specimens have been dept in water, in chloride acid, in sulfuric acid and in ammonia sulfate acid for a period of 92 days. Attacks have provoked an important dissolution of calcium hydroxide and calcium sulfate of the materials. Then, calcium carbonate and gypsum have precipitated in the solution. The precipitates contained also cimentitious phases fallen from the porous system. The degradations have caused a strong decrease of the 3-points flexural strengths, whereas the compressive strengths and the hardness have less decreased. An addition of 30% of Portland cement in the Kerysten® improves the chemical resistant of the material. Thanks to Kerysten®, cimentitious phases have been less dissolved. Thanks to Portland cement, strengths stayed good
Sadok, El-Habib. "Rôles compares des cations étrangers en solution dans l’étape de germination associée à l'hydratation des sulfates de calcium et de l'aluminate mono calcique." Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0058.
Повний текст джерелаBerry, Jeffrey Nicholas. "Sulfate in foraminiferal calcium carbonate : investigating a potential proxy for sea water carbonate ion concentration." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/53536.
Повний текст джерелаIncludes bibliographical references (leaves 82-85).
The sulfur content of planktonic and benthic foraminifera was measured in specimens recovered from deep-sea sediment cores and individuals grown in culture. A new method for measuring sulfur in foraminiferal calcium carbonate was developed, employing a high-resolution inductively coupled plasma-mass spectrometer. The sulfur measurements, expressed as sulfur-to-calcium (S/Ca) ratios in the foraminiferal shells, ranged from 0.26 to 6.0 mmol/mol. Most analyses fell in the range of 0.7 to 2.5 mmol/mol. Culturing experiments were conducted in the planktonic foraminifer G. sacculifer to test the hypothesis that S/Ca ratios in the foraminifer are inversely proportional to the carbonate ion concentration in the seawater in which they grow, and hence proportional to the pH of the seawater. The slope of the relationship between cultured G. sacculifer S/Ca and the pH of the seawater medium was -1.92 mmol mol-1/pH unit with a least squares linear correlation coefficient, r2=0.927. The S/Ca ratios of planktonic and benthic foraminifera from Holocene and last glacial period sediments were measured in an effort to use the established relationship of S/Ca and pH to calculate the ocean pH gradient between Holocene and glacial time. The results indicate the pH of global ocean deepwater was 0.10 to 0.15 pH units higher during glacial time than today. Smaller pH gradients were seen for some cores which may have been caused by circulation-induced water mass changes. Surface ocean changes in pH over the Holocene-glacial interval seem to vary from region to region, with up to an 0.2 pH unit increase at the Sierra Leone Rise in glacial time. Benthic foraminifera from coretops in the thermocline of the Little Bahama Bank were analyzed for S/Ca to examine the effects of hydrographic variables on S/Ca. The relationship of S/Ca to pH and [CO3=] has a positive slope, at odds with the expected negative slope from the previous results. The S/Ca results do correlate well with salinity, suggesting that salinity or other hydrographic parameters may also influence foraminiferal S/Ca ratios.
by Jeffrey Nicholas Berry.
M.S.
DADKHAH, MEHRAN. "Preparation and characterization of a Novel mesoporous bioactive glass/calcium sulfate cement for vertebroplasty application." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2678646.
Повний текст джерелаHalfen, Doris Pereira. "Adição de fontes de enxofre e cálcio na dieta de gatos adultos e seus efeitos no ph urinário e equilíbrio ácido-básico." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/149324.
Повний текст джерелаUrolithiasis is a commom problem in the veterinary clinic considered as a cause of morbidity. The urolithiasis are closely associated with urinary pH and nutrition plays a key role in the control of this disease, because through dietary manipulation, it´s possible modify the urinary pH. The diet has cations and anions in their mineral composition and the difference between ions is measured in milliequivalents (mEq/kg) and called base excess (BE) of the diet, calculated by the equation: (49.9 x Ca) + (82, Mg x 3) + (43.5 x Na) + (25.6 x K) - (64.6 x P) - (62.4 x S) - (28.2 x Cl), being the concentration of elements in g/kg DM. The purpose of this study, divided in two experiments, was to evaluate the effect of addition of sources of sulfur (S) and calcium in the diets of cats on the urinary pH and acid-base balance. The addition of sulfur sources aimed to demonstrate the efficacy in urinary acidification. In the first experiment were evaluated three different sources of sulfur, calcium sulfate (CaSO4), DLMethionine (DLM) and Methionine hydroxy analogue (MHA) added to a control diet at two levels each. In the control treatment there was no addition of acidifying. At the first level was added 1.28 g S/kg and in the second 2.56 g S/kg, resulting in seven treatments. In the second experiment two calcium sources were evaluated in order to research the effectiveness of these salts in alkalinize urine. In the control treatment there was no addition of calcium sources. In treatments 2 and 3 were added to the control diet calcium carbonate and calcium gluconate, respectively, at doses of +160 mEq/kg, resulting in three treatments. The urine produced in each period of 24 hours had measured its volume, density and pH. The second experiment also measured the urinary excretion of calcium in the period of 72 hours. The acid-base balance was evaluated by blood gas analysis of venous blood. The DLM at the highest level and MHA differed of the control diet in relation to urinary pH (p<0.001) and their acidifying power was greater than the calcium sulfate (p<0.05). The two sources of calcium alkalinized the urine, but the calcium carbonate reached a urine pH higher than calcium gluconate. It was concluded that the effect of different sources of S and calcium on urinary pH is an indicator that the participation of calcium is dependent of the anions that is associated, which leads to questions about how is the best way to evaluate its participation in calculation of BE.
El, Mornan Abdelmjid. "Synthèse, comportement thermique et réactivité de la solution solide gypse-brushite (1-x) CaSO4, 2H2O-xCaHPO4, 2 H2O (x<0,2) et de ses produits de déshydratation." Lyon 1, 1990. http://www.theses.fr/1990LYO10186.
Повний текст джерелаMarden, Torres Sandro. "The influence of chloride on the thaumasite form of sulfate attack in mortars containing calcium carbonate." Thesis, University of Sheffield, 2004. http://etheses.whiterose.ac.uk/6064/.
Повний текст джерелаShih, Wen-Yi. "Formation and control of calcium sulfate dihydrate (gypsum) crystallization on RO membranes and surrogate polymeric surfaces." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1383480211&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Повний текст джерелаKobata, Robert Steven 1954. "AN AUTOMATED METHOD OF MEASURING ISOLATED MUSCLE CONTRACTION (VERAPAMIL, HALOTHANE, CALCIUM-CHLORIDE, MAGNESIUM SULFATE, GUINEA PIG)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/277003.
Повний текст джерелаBeltagui, Hoda. "The influence of gypsum on the hydration kinetics and the microstructure of calcium sulfoaluminate cements in sulfate-rich environmnets." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231270.
Повний текст джерелаMartias, Céline. "Synthèse et caractérisation de matériaux composites à base de sulfate de calcium destinés à la protection incendie." Phd thesis, Toulon, 2011. http://tel.archives-ouvertes.fr/tel-00769952.
Повний текст джерелаKuryatnyk, Tetyana. "Insensibilisation à l'eau des mélanges à base de sulfate de calcium par ajout de clinker sulfo-alumineux." Lyon, INSA, 2007. http://theses.insa-lyon.fr/publication/2007ISAL0062/these.pdf.
Повний текст джерелаBinders based on calcium sulfate are cheap but vulnerable in water due to their high solubility. The capacity of calcium sulfo-aluminate clinker to stabilize calcium sulfate based binders as well as the influence of the nature of calcium sulfate on the mechanical properties and microstructure of such materials were investigated. Waterproofing of gypsum based binders was carried out by addition of 30, 50 and 70 % of calcium sulfo-aluminate clinker. The present study compares the bihaviour of pastes containing respectively natural gypsum, recristallized gypsum, and β hemi-hydrate. The study of the hydration of calcium sulfate based binders containing 30, 50 and 70 % of calcium sulfo-aluminate clinker has been carried out by means of XRD, DTA, and IR spectrometry. It was pointed out that ettringite and gibbsite are the main hydrates that formed regardless of the calcium sulfate to calcium sulfo-aluminate clinker ratio or the nature of calcium sulfate. The main factors determining the microstructure and thus the physical properties and the durability of material were the following : W / C ratio, conditions of curing (water or in air), percentage of added calcium sulfo-aluminate clinker, and nature of calcium sulfate. From this study, it became possible to determine the minimal quantity (30 %) of calcium sulfo-aluminate clinker ensuring the stability in water of the different mixtures
Kuryatnyk, Tetyana Pera Jean Derevianko Viktor. "Insensibilisation à l'eau des mélanges à base de sulfate de calcium par ajout de clinker sulfo-alumineux." Villeurbanne : Doc'INSA, 2007. http://docinsa.insa-lyon.fr/these/pont.php?&id=kuryatnyk.
Повний текст джерелаPereira, Rodrigo de Paula. "A atividade antimicrobiana de agentes desinfetantes incorporados ao gesso tipo IV /." Araraquara : [s.n.], 2009. http://hdl.handle.net/11449/98032.
Повний текст джерелаBanca: Sérgio Sualdini Nogueira
Banca: Vinícius Pedrazzi
Resumo: Vários protocolos de desinfecção podem ser usados para romper a cadeia de infecção cruzada entre o consultório odontológico e o laboratório de prótese. A inclusão de agentes antimicrobianos à composição do gesso ou a manipulação do gesso com soluções desinfetantes podem ser usados com esta finalidade. O propósito deste estudo foi avaliar a atividade antimicrobiana de dois agentes desinfetantes (digluconato de clorexidina 2% e cloridrato de clorexidina 98%) incorporados ao gesso IV (FujiRock - GC Europe, Leuven, Bélgica) durante sua manipulação. No teste microbiológico de difusão em Agar foram uti l izados os seguintes microorganismos: Escherichia coli, Staphylococcus aureus, Bacilus subtilis e Candida albicans. Amostras com 5 mm de diâmetro e 3 mm de espessura foram separadas em quatro grupos: 1) gesso manipulado com água destilada esterilizada (controle positivo); 2) discos de papel embebidos com solução de digluconato de clorexidina 2% (controle negativo); 3) gesso manipulado com solução de digluconato de clorexidina 2%; 4) gesso com a incorporação de cloridrato de clorexidina 98% em pó, na proporção de 1% da massa do gesso, e manipulado com água destilada esterilizada. Após 1 hora e 24 horas do vazamento do gesso, as amostras foram posicionadas em placas de Petri com meios de cul tura específicos inoculados com as suspensões microbianas. A atividade antimicrobiana dos desinfetantes foi avaliada pelo diâmetro médio dos halos de inibição do crescimento microbiano. Os valores foram analisados pela ANOVA Aninhada (p<0,05) e teste de Tukey para comparações específicas. Os resultados encontrados demonstraram que os agentes desinfetantes analisados apresentaram atividade antimicrobiana quando misturados ao gesso, com exceção para Candida albicans, na qual não houve efeito da solução de clorexidina nos dois períodos de análise... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Many protocols for disinfection procedures can be used to break the chain of cross-contamination between dental office and dental laboratory. The inclusion of antimicrobial agent to the composition of gypsum or the manipulat ion of gypsum with disinfectant substances can be used to that aim. The purpose of this study was to evaluate the antimicrobial activity of two disinfectant agents (2% chlorhexidine digluconate and 98% chlorhexidine hydrochloride) incorporated into type IV dental stone (FujiRock - GC Europe, Leuven, Belgium) at the time of mixing. The microbiological test used was the Agar diffusion test to the following microorganisms: Escherichia coli, Staphylococcus aureus, Bacilus subtilis and Candida albicans. Samples of 5 mm in diameter and 3 mm in length were separated in four groups: 1) dental stone mixed wi th steri le distilled water (positive control); 2) paper disk soaked wi th solution of 2% chlorhexidine digluconate (negative control); 3) dental stone mixed with solution of 2% chlorhexidine digluconate; 4) dental stone wi th incorporation of chlorhexidine hydrochloride 98% powder, in proportion of 1% of the dental stone mass, and mixed with sterile distilled water. The samples were placed, 1 hour and 24 hours after pouring of dental stone, in Petri plates with specific cul ture medium wich were inoculated with the microbial suspensions. The antimicrobial activity of disinfectant was evaluated by the average diameter of microbial growth inhibi tion zones. The data were analyzed with a Nested ANOVA (p<0,05) and Tukey test for specific comparisons. The disinfectant agents analyzed demonstrated antimicrobial effect against microorganisms used in this study, in exception to Candida albicans, against wich there was not effect from chlorhexidine digluconate at two periods of analysis. Significant difference between disinfectantes were found to all microrganisms... (Complete abstract click electronic access below)
Mestre
Sanches, Carlos Vinícius [UNESP]. "Disponibilidade de Ni em um latossolo vermelho distrófico em função da aplicação de gesso agrícola e caracterização fisiológica e bioquímica do algodoeiro." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151924.
Повний текст джерелаApproved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-10-18T18:46:06Z (GMT) No. of bitstreams: 1 sanches_cv_me_ilha.pdf: 1153134 bytes, checksum: e1a87166456fa7557998258f42005db3 (MD5)
Made available in DSpace on 2017-10-18T18:46:06Z (GMT). No. of bitstreams: 1 sanches_cv_me_ilha.pdf: 1153134 bytes, checksum: e1a87166456fa7557998258f42005db3 (MD5) Previous issue date: 2017-08-18
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O algodoeiro apresenta uma sensibilidade elevada nos sistemas de cultivo. A acidez do solo aliada a alta concentração alumínio e a baixa disponibilidade de cálcio em profundidade podem limitar a produtividade sendo possível verificar distúrbios nutricionais. Nesse contexto, o níquel, nutriente essencial, componente da metaloenzima urease tem sua importância comprovada no metabolismo do nitrogênio e vem sendo estudado como alternativa para melhorar a qualidade do sistema de cultivo por meio da eficiência do uso do nitrogênio disponível. Outra vertente de estudos diz respeito a capacidade do níquel de agir como metal pesado sendo prejudicial para as culturas, dessa maneira faz-se necessário entender a dinâmica desse nutriente dentro dos sistemas de cultivo. Tendo em vista o exposto, o objetivo deste trabalho foi verificar os efeitos da aplicação de diferentes doses de níquel e gesso, e a interação entre os dois sobre o crescimento, produtividade e estado nutricional de plantas de algodoeiro em condições de campo. O experimento foi desenvolvido em dois anos, os tratamentos utilizados foram 0,0; 1,0; 2,0; 6,0; 12 e 16 kg ha-1 de Ni e 0, 200, 400 e 800 kg ha-1 de gesso, aplicados via solo. Utilizou-se o delineamento em blocos ao acaso em um fatorial 6x4 com 3 repetições. Para mensurar o efeito dos tratamentos, os parâmetros de crescimento (altura, diâmetro e número de ramos), estado nutricional (P, K, Ca, Mg, S, Cu, Fe, Mn, Zn e Ni), e produtividade (número de estruturas reprodutivas, produtividade de algodão em caroço, rendimento de fibra e massa de 20 capulhos), foram submetidos a análise de variância e regressão polinomial por meio do software de análise estatística Sisvar 5.1. Há variações na produtividade em função das condições climáticas, em déficit hídrico severo foi possível concluir que o aumento na dose de gesso pode reduzir a produtividade do algodoeiro linearmente, a aplicação de doses de níquel e gesso, nas condições apresentadas nesse experimento, não exercem influência no crescimento e desenvolvimento do algodoeiro. O fornecimento de gesso até 800 kg/ha interfere na absorção de Ni, verifica-se um antagonismo entre cálcio e níquel. O fornecimento de níquel via solo não interfere na absorção de nutrientes com exceção do cálcio. O cálcio exerce antagonismo em relação ao manganês. As doses de níquel não promoveram efeitos positivos ou negativos no crescimento e desenvolvimento do algodoeiro.
The cotton plant has a high sensitivity in the cropping systems. The soil acidity allied to high aluminum concentration and low calcium availability in depth may limit the productivity and develop nutritional disorders. In this context, nickel, essential element, component of metalloenzyme urease, has its importance proven in the nitrogen metabolism. It has been studied as an alternative to improve the cropping system quality through an efficient use of the available nitrogen. Another strand of studies mentions about the nickel capacity to act as a heavy metal and being harmful to the crops, thereby making it necessary to understand this nutrient dynamic within the cropping systems. Based on the foregoing, the objective of this study was to verify the effects of the application of different nickel and gypsum doses, and the interaction between them on the growth, crop yield and nutritional status of cotton plants under field conditions. The experiment was conducted in two years, the treatments used were 0,0; 1,0; 2,0; 6,0; 12 and 16 kg ha-1 of Ni and 0, 200, 400 and 800 kg ha-1 of gypsum, applied via soil. A randomized complete block design was used in a 6x4 factorial scheme with 3 repetitions. In order to measure the treatment effects, the parameters of growth (high, diameter and number of branches), nutritional status (P, K, Ca, Mg, S, Cu, Fe, Mn, Zn and Ni), and crop yield (number of reproductive structures, seed cotton yield, fiber cotton yield and mass of 20 cotton bolls), were submitted to an analysis of variance and polynomial regression through a software of statistical analysis Sisvar 5.1. There are variations in the crop yield in function of the climate conditions; in severe water deficit, it was possible to conclude that the increase in gypsum doses can reduce cotton crop yield linearly. The application of doses of nickel and gypsum, under the conditions presented, do not influence the growth and development of the cotton plants. The supply of gypsum up to 800 kg ha-1 interfere in the absorption of Ni, verifying an antagonism between calcium and nickel. The supply of nickel via soil do not interfere in the nutrients absorption with exception of calcium, which exerts antagonism over manganese. The doses of nickel did not promote positive or negatives effects in the growth and development of the cotton plants.
Bingol, Onur Rauf. "Hydrothermal-like Synthesis Of Hydroxyapatite From Calcium Sulfates." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612425/index.pdf.
Повний текст джерела0.5H2O, PoP) and gypsum (CaSO4&bull
2H2O) has been performed. HAp synthesis was achieved by reacting 1 M of (NH4)2HPO4 (or 0.5 M of (NH4)2HPO4) solutions with solid calcium sulfate precursors under ambient pressure (1 atm) and hydrothermal-like (2 ±
0.2 atm, 120 °
C) conditions. Under ambient conditions, HAp formation kinetics was investigated at 25 °
C, 50 °
C and 90 °
C using 1 M of (NH4)2HPO4 solution. Conversion to HAp at such low temperature takes more than 21 days and it also promotes formation of additional calcium phosphate with HAp. At 25 °
C, HAp formation started after 7 days accompanied with formation of brushite (CaHPO4&bull
2H2O). At 50 °
C no significant conversion was observed after 6 h. However, at 90 °
C, phase pure HAp was formed after 2 h. On the other hand, under hydrothermal-like conditions, the HAp formation proceed much faster and it was also shown that HAp could be also synthesized from gypsum powders and bulk gypsum pellets. Using 1 M of (NH4)2HPO4 solution, HAp formation from PoP started 15 min and completed almost in 30 min, whereas 0.5 M of (NH4)2HPO4 reactant solution slowed down the conversion. The exact chemical identity of the HAp product of hydrothermal-like reaction was evaluated by post-synthesis calcinations and the thermal phase stability was related with the stoichiometry (Ca/P at ratio) of the HAp. The HAp phase was stable up to 600 °
C and above 600 °
C, &beta
-tricalcium phosphate (&beta
-Ca3(PO4)2, &beta
-TCP) was formed, suggesting that the resultant HAp was calcium-deficient. Mechanical testing by diametrical compression was performed to the HAp samples produced from bulk gypsum pellets. The strength was measured 1.2 MPa with highest solid to liquid (s:l) ratio 3.33 and decreased with s:l ratio. This change was found to be related with the porosity differences due to differences in s:l ratio. Additional mechanical tests were applied to the polycaprolactone (PCL) coated bulk HAp pellets for which the tensile strength was doubled. This study presents an easy and feasible method for production of HAp from a cheap and abundant calcium source &ndash
PoP. In addition, the findings provide a potential processing route for developing irregularly shaped bulk porous HAp structures.
Hsia, Chungwei. "Mechanisms and rate of solid state diffusion in iridium-hafnium intermetallic compound (iridium(3) hafnium) and calcium sulfate /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848078448938.
Повний текст джерелаPoupelloz, Estelle. "Etude des processus de germination-croissance de l'ettringite, seule ou dans un système aluminate tricalcique/sulfate de calcium." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCK055.
Повний текст джерелаEttringite Ca6Al2(SO4)3(OH)12.26H2O is one of the main hydration products of cements but despite the importance of this compound for cement chemistry, laws governing its precipitation processes have been poorly studied. This PhD thesis was entirely focused on the study of ettringite and on its nucleation-growth mechanisms.Ettringite precipitation was first studied alone from supersaturated ionic solutions. Experiments were designed in order to study separately processes of nucleation and growth. The Classical Theory of Nucleation was applied and allowed the determination of the interfacial energy of ettringite. A global description of ettringite precipitation process has been suggested. It appeared that ettringite is an easily formed hydrate, because of its low interfacial energy, presenting a high precipitation rate as soon as its constitituve ions are present in solution. After primary homogeneous nucleation, when the quantity of already formed crystals is still low, precipitation rate of ettringite mainly depends on the supersaturation degree of the solution. When the crystalline surface gets significative, it provokes an increase of precipitation rate and processes of secondary nucleation and growth have been identified.Then, formation of ettringite during the hydration of a C$_3$A/calcium sulfate system, chosen to get closer to chemical reactions happening in a Portland cement, was studied. Conducted experiments helped prove that a growing concentration of sulfate ions (and of calcium ions) in solution was speeding up ettringite precipitation. Obtained results about the ease and speed of ettringite precipitation alone from supersaturated solutions seem also valid in the case of ettringite formation during the hydration of a C$_3$A/CaSO$_4$ system
Silva, Marcos Aurelio Bomfim da 1983. "Propriedades físicas de gessos odontológicos tipo IV desidratados em temperatura ambiente e em forno de microondas." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288550.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-17T13:52:59Z (GMT). No. of bitstreams: 1 Silva_MarcosAurelioBomfimda_M.pdf: 1487583 bytes, checksum: 9cb32f8fb3e02fe5c0534b01b7a60277 (MD5) Previous issue date: 2011
Resumo: O objetivo deste estudo foi verificar a influência da secagem em temperatura de laboratório (25±4ºC) e em forno de microondas sobre propriedades físicas de gessos odontológicos tipo IV: Elite Rock, Shera Premium e Durone IV. Os gessos foram proporcionados e espatulados mecanicamente a vácuo seguindo as recomendações dos fabricantes e vazado no molde com auxílio de vibrador mecânico. No Capítulo 1 foi avaliada a alteração dimensional, resistência à compressão e reprodução de detalhes dos gessos desidratados em forno de microondas e em temperatura de laboratório. Dois protocolos de desidratação com diferentes períodos de avaliação foram utilizados para os ensaios de alteração dimensional, resistência à compressão e reprodução de detalhes dos gessos foram utilizados e divididos em 4 grupos com: G1- temperatura de laboratório (25 ± 4ºC) no período de 2 horas; G2- temperatura de laboratório após 24 horas; G3- temperatura de laboratório após 7 dias e G4- microondas com potência de 800 W por 5 minutos após 2 horas. No Capitulo 2 foi avaliada a influência de diferentes potências de radiação do forno de microondas durante a secagem dos gessos sobre a alteração dimensional e resistência à compressão. Foram utilizados seis diferentes métodos de secagem e divididos em seis grupos: G1-temperatura ambiente no período de 2 horas; G2- temperatura ambiente no período de 24 horas; G3- temperatura ambiente no período de 7 dias; G4- microondas com potência de 200 W por 5 minutos; G5- microondas com potência média 400 W por 5 minutos e G6- microondas com potência alta 800 W por 5 minutos. Nos capítulos 1 e 2 para o ensaio de alteração dimensional linear foram confeccionadas amostras utilizando matriz metálica com entalhes de diferentes profundidades e distância entre as linhas de 2,5 mm. Em seguida, a superfície foi escaneada com resolução de 1200 dpi e analisada com software ImageTool 3.0. Para o ensaio de resistência à compressão foram confeccionados moldes de silicone polimerizada por condensação, a partir de uma matriz metálica cilíndrica medindo 20 mm de comprimento por 10 mm de diâmetro. Para o ensaio de reprodução de detalhes executada somente no capítulo 1, a análise foi feita na linha central da matriz reproduzida na superfície da amostra de gesso. Os dados foram submetidos à análise de variância (ANOVA) com dois fatores e as médias ao teste de Tukey com nível de 5% de significância. Capitulo 1: No G1, as três marcas comerciais apresentaram maiores níveis de expansão dimensional sendo diferentes estatisticamente entre os grupos 2, 3 e 4. Para o ensaio de resistência à compressão os gessos Elite Rock e Durone IV não apresentaram diferença estatística significante entre G2 e G4, exceto para Shera Premium não apresentando diferença entre G3 e G4. Os melhores índices de reprodução ocorreram para G3. Capítulo 2: Os valores de alteração dimensional para o gesso Elite Rock foram estatisticamente semelhantes entre G3 e G6 e entre G4,G5 e G2. O gesso Shera Premium apresentou maiores níveis de expansão para G1 em relação a G2, G3, G4, G5, G6. Para o gesso Durone IV o G5 apresentou os menos valores de expansão dimensional. Para as três marcas comerciais utilizadas, a desidratação em forno de microondas com potência de 200 W e em temperatura de laboratório após 7 dias promoveu resistência à compressão sem diferença estatística e significativamente maiores,com exceção do Shera Premium e Durone IV que produziram valores semelhantes com potência de 800 W e 400W respectivamente. Os gessos odontológicos tipo IV apresentaram melhora em suas propriedades com secagem em forno de microondas. A potência de 200 W a 800 W proporcionaram níveis de alteração dimensional similares aos desidratados em temperatura de laboratório após 24 horas e 7 dias. A potência de 200 W produz maiores valores de resistência à compressão para Elite Rock.
Abstract: The objective of this study was to assess the effect of drying laboratory temperature (25 ± 4 ° C) and in microwave oven on the physical properties of dental stone type IV: Rock Elite, Premium and Shera Durone IV. Plasters were proportionate and spatulate mechanically vacuum following the manufacturers recommendations and poured into the mold with the aid of mechanical vibrator. In Chapter 1 we evaluated the dimensional change, compressive strength and detail reproduction of plaster dried in a microwave oven and a temperature of the laboratory. Two different protocols of dehydration for tests of dimensional change, compressive strength and detail reproduction of plaster casts were used and divided into four groups: G1-temperature laboratory (25 ± 4 ° C) in 2 hours, G2- temperature laboratory after 24 hours, G3-temperature laboratory after 7 days and G4-microwave power of 800 W for 5 minutes after 2 hours. In Chapter 2 we evaluated the effects of different energy radiation from the microwave oven during the drying of plaster on the dimensional changes and compressive strength. We used six different methods of drying and divided into six groups: G1-room temperature within 2 hours; G2-room temperature within 24 hours; G3-temperature environment within 7 days: G4-microwave power of 200 W for 5 minutes and G5- average microwave power 400 W for 5 minutes, G6-high microwave power 800 W for 5 minutes. In chapters 1 and 2 for testing dimensional linear samples were prepared using metal matrix with notches of different depths and distance between lines of 2.5 mm. Then the surface was scanned at 1200 dpi and analyzed with software ImageTool 3.0. For testing the compressive strength silicone molds were prepared by condensation polymerized in cylindrical stainless steel mold measuring 20 mm by 10 mm in diameter. To test the reproduction of details performed only in chapter 1, the analysis was performed on the center line of the matrix reproduced on the sample surface of plaster. Data were subjected to analysis of variance (ANOVA) with two factors and the means with Tukey test at 5% level of significance. Chapter 1: In G1 of three commercial brands showed higher levels of dimensional expansion was statistically significant between groups 2,3 and 4. For testing the compressive strength gypsum Durone Elite Rock and IV showed no statistically significant difference between G2 and G4, except for Premium Shera no difference between G3 and G4. The highest rates of reproduction were to G3. Chapter 2: The values of dimensional change to the cast Elite Rock showed statistically similar values among and between G3 and G6, G4, G5 and G2. Gypsum Premium Shera had higher levels of expansion in G1 compared to G2, G3, G4, G5, G6. For plaster Durone IV G5 showed the least values of dimensional expansion. For the three trademarks used, drying in a microwave oven with a power of 200 W and temperature in the laboratory after 7 days promoted the compressive strength and not statistically significantly higher, except for the Premium and Shera Durone IV that produced similar values with power of 800 W and 400W respectively. Dental stone type IV showed improvement in their properties with drying in a microwave oven. The power of 200 W to 800 W gave similar levels of dimensional change in the dehydration temperature of the laboratory after 24 hours and 7 days. The power of 200 W produces higher values of compressive strength for Elite Rock.
Mestrado
Materiais Dentarios
Mestre em Materiais Dentários
Tekkouk, Abdelhadi. "Contribution à l'étude des interactions micro-ondes-matière condensée : cas d'un matériau de construction, le sulfate de calcium semihydraté." Lyon 1, 1989. http://www.theses.fr/1989LYO10073.
Повний текст джерелаБольшаніна, Світлана Борисівна, Светлана Борисовна Большанина, Svitlana Borysivna Bolshanina, Лариса Іванівна Марченко, Лариса Ивановна Марченко, Larysa Ivanivna Marchenko, Олексій Германович Аблєєв, Алексей Германович Аблеев та Oleksii Hermanovych Ablieiev. "Исследование твердой фазы при гидратации полугидрата сульфата кальция". Thesis, Издательство СумГУ, 2007. http://essuir.sumdu.edu.ua/handle/123456789/19014.
Повний текст джерелаBenhidjeb, Nadra. "Etude théorique et expérimentale de l'évolution de la structure poreuse lors de la sulfatation de la chaux." Mulhouse, 1996. http://www.theses.fr/1996MULH0442.
Повний текст джерелаHsin-YiLiu and 劉欣宜. "Hill Sachs Lesion Repaired by Injectable Alpha Calcium Sulfate Hemihydrate." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/82448628183765848379.
Повний текст джерела國立成功大學
生物醫學工程學系
103
The Hill-Sachs lesion is usually caused by shoulder dislocation at glenohumeral joint which is a ball and socket structure, and the dimension of humeral head is larger than glenoid fossa which makes it unstable and easily being dislocated. The dislocation causes the superior labrum anterior to posterior lesion and impinges into the bone, making engaging Hill-Sachs defect that is participated for the range of motion (ROM) in the 30% to 40% circumscribed. The Hill-Sachs lesion has been reported in high possibility of recurrent anterior dislocations. When the instability of the shoulder gets worse caused by Hill-Sachs defect, the patient will suffer severe pain and the defect should consider surgical repair. Several autologous grafts and synthetic materials have been used as graft material; however, their availability and biocompatibility limit their clinical outcome. Thus, this study investigates to treat the Hill-Sachs lesion with injectable alpha Calcium Sulfate Hemihydrate (αCSH). It is possible to be used inside the human body as bone filler. Virtually, the αCSH has been noticed having the characteristics of the osteo-induction and osteo-conduction in vivo; however, it has never been applied as bone filler to repair the Hill-Sachs defect. This study tests the possibility of using αCSH to repair the Hill-Sachs defect and was divided into three parts including αCSH characterization, in vitro biocompatibility of αCSH and in vivo Hill-Sachs model in rabbits: Part 1 Material preparation: The preparation of αCSH was from heat treatment of Calcium Sulfate Dihydrate (CSD, J.T. Baker) and the heat treatment conditions were evaluated by Differential Scanning Calorimetry (DSC) and Thermogravimetry Analysis (TGA). The result of DSC curve had first endothermic peak (△H=713.54 J/g) at 120-140℃ which means 2H2O converts to 1/2H2O, and there is the second endothermic peak (△H=144.54 J/g) at 140-150℃ for 1/2H2O to non-aqueous. Also, the TGA curve of CSD and CSH shows the decreasing in weight around 119.5℃. Combined the DSC and TGA results we defined the heat treatment temperature at 127℃ under 5kg/cm2 pressure for 9 hours. In the results of X-ray Diffraction (XRD) which match with JCPDS card and Jade system were to identify the completeness of phase transformation. The primary crystal planes of CSD were located at (020), (021), and (041). After 9 hours heat treatment the crystal planes of CSD were convert to αCSH at (010), (310), and (202). In spite of that the XRD still cannot specific determine the kind of crystallize (α or β phase), the microstructure from scanning electron microscopy (SEM) was used to further identify the crystal formation. In the SEM images of CSD with wider arrangement which the particles size were 163.06±11μm in length and 28.45±6.53μm in width (N=5). The microstructure of αCSH were with needle-shaped which particles size were 92.02±63μm in length and 17.31±2.4μm in width (N=5), from H2O evaporation. In addition, the compressive strength of αCSH was tested by Materials Test Systems by following the ASTM 451-99a. The compressive strength of αCSH hardening with DD water was at 5.39±0.42MPa (N=6) and the αCSH with curing agent was enhanced the compressive stress to 9.62±2.05MPa (N=6). However, the curing time of αCSH/DD water and the αCSH/HCl were with no significant difference at 10-14 minutes and with proper hardening time for surgery. (N=6) Besides, the degradation of materials was with similar degradation rate about 25% weight loss after 49 days and the pH value at 5.5-6.0. However the αCSH/ HCl group has a stronger chemical bounding which can effectively control the release of calcium ions in the results of EDS after 49 days. All of the scaffolds had no significant change for the appearance after 49 days degradation. Therefore, the microstructure of hardening material of αCSH/ DD water has an interlocking structure with 58% of porosity (N=10). However, the material of αCSH/HCl demonstrated the glue-like structure with 47% of porosity (N=10). Both materials have a pore size of 10-100 μm which is adequate dimension for cell migration and attachment. Part 2 in vitro test: A human osteoblast-like cell line, MG63 (Homo sapiens bone osteosarcoma), was used to test the biocompatibility of αCSH/DD water, αCSH/HCl, and 15% alginate and followed by ISO-10993-5. The cytotoxicity of αCSH/DD water and αCSH/HCl group which co-cultured with 5×104 cells in 24-well plates in DMEM (Dulbecco’s Modified Eagle Medium) containing 10% Fetal Bovine Serum, 1% penicillin-streptomycin and saturation concentration of material powder. The alginate was coated with 0.1 cc material on the 24-well plates and co-cultured with 5×104 cells. After the incubation of cells with materials for 1, 3, 5, and7 days, absorbance was set at 490 nm to evaluate the cell viability in response to the cytotoxicity of materials. The results of MTS assay shows the co-cultured cells with materials had no significant difference of cytotoxicity compared with control group. (P〉0.05) The cell attachments of materials were followed by ASTM F813-83. The scaffolds were seeded with 5×104 cells on the surface and incubated in 24 well plates, observed at 1, 3, 5 days. They were dehydrated in a graded series of ethanol, treated with 10% paraformaldehyde, coated with gold, and observed by SEM. In the results of microscopy demonstrated that cells were extended and attached on the scaffolds successfully after 1 day. Cells were spread all over the surface of scaffolds and with plenty of secretion, after 5 days. The SEM shows the cells had migrated into the cut in halve scaffold at day 5. In bounding test, the humeral heads of pork were used in the push out test. The material without alginate drops out from the bone defect after immersing in Hank’s solution for 5 minutes. However, the material with alginate was effectively attached on the bone defect and the bounding force had reached to 1.73±0.26 MPa (N=6) Part 3 in vivo test: The Hill-Sachs model was built by creating a defect on rabbit’s humeral head. The size and location of defect to mimic the Hill-Sachs defect was verified by histology and micro-CT after sacrificed. Defect size was 25% of humeral head and the diameter was 7.5mm and the depth was 5mm. The deflection depth was too deep which destroy the bone marrow and cause angiostasis which lead to a failure of attaching the materials into the bone defects. Therefore, the materials were injected two weeks after the surgery. The process of mixing αCSH and hardening solution are1:1 ratio at room temperature with stirring for 60 seconds then it was injected with 15% alginate.αCSH hardening reaction took 10 to 11 minutes of curing time at body temperature (37 °C) The functionality of repairing Hill-Sachs defect after αCSH injection were evaluated by radiography and histology at 4 and 12 weeks postoperatively. CT analysis shows, the bone remodeling had tissue regeneration starting from the edge of defect and the residue of materials were showed on the 2D image after 4 weeks. In contrast, the defect without treatment had no obvious tissue repaired on the 2D image after 4 weeks. However, the material had been completely replaced by the newly bone after 12 weeks. In the result of 3D reorganization, the bone defect had well appearance after 4 and 12weeks (N=6). The value of BV/TV showed that the material groups had obvious difference with defect groups (P〈0.05). Furthermore, there were no significant difference compare with defect group treated with materials after 12 weeks and the control group. (P〉0.05) The histology applied with HE and Masson trichrome staining by paraffin sections for 4μm was use to confirm the bone regeneration. In the results of histology, the bone repaired started from the edge, the plenty of osteoblasts had migrated into the material and the connective tissue showed the connection between newly bone and the material after 4 weeks. However, the defect group had no tissue regeneration on histology after 4 weeks. Besides, the bone regeneration of material group has been completed, comparing with the defect group which was 100-700μm regenerated after 12 weeks. The αCSH/HCl/Alginate provided a simple preparation of injectable performance with great biocompatibility in vitro and bone repaired, which has a potential in repairing the Hill-Sachs defect surgery.
Chuang, Fu-Yu, and 莊馥瑜. "Study on Calcium Sulfate Hemihydrate added Tricalcium Phosphate/Calcium Citrate Bone Cement Composites." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/43s6mg.
Повний текст джерела龍華科技大學
化工與材料工程系碩士班
106
Calcium Sulfate Hemihydrate has been used as a bone substitute for more than one hundred years. It has good biocompatibility, good mechanical strength, and short curing time. The disadvantage is that the degradation rate in the human body is too fast, and it is necessary to rely on other chemicals to prolong its absorption. In this study, Calcium Sulfate Hemihydrate was used as the main Bone Cement composite material, Tricalcium Phosphate and Calcium Citrate were added according to different proportions. A series of experiments were carried out on curing time, mechanical properties analysis, weight loss, XRD analysis and surface structure microscopic analysis. According to the result of the experiment, by soaking artificial body fluid experiment found that the Calcium Sulfate Hemihydrate/Tricalcium Phosphate Bone Cement (CSHTCP) and the Bone Cement Calcium Sulfate Hemihydrate/Calcium Citrate Bone Cement (CSHCC), as the soaking time is longer, the surface arrangement is gradually loose, and the weight loss is also greater. Where the pH value of the immersion test, the pH value turn from neutral to weak acid and it meets the pH value of human body. In the XRD analysis , it was found that the lower the pH of the Bone Cement composites, the stronger the peak value, and the crystallized out of the calcium phosphate rock, in which the CSHCC Bone Cement is stronger, and the citrate-containing component accelerates the growth of the brushite.
Hsieh, Yueh-chih, and 謝岳池. "In-Vitro Study of Calcium Sulfate Hemihydrated and Calcium Carbonate Composites Material." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/8b6x7z.
Повний текст джерела國立臺北科技大學
材料及資源工程系研究所
99
Because of their excellent biocompatibility, both Calcium carbonate (CaSO4) and Calcium carbonate (CaCO3) are widely used as the bone defect repair materials. However, the fast rate of CaSO4 degradation might cause defects during the implantation, which will obstruct the growth of the bone. Calcium carbonates are used as hydration accelerator and filler component within composites, which reduce the setting time and promote the mechanical strength of calcium composite paste. In this experiment, an optimal incorporation ratio of CaCO3 into CaSO4 bone filler system was introduced. SEM and XRD were used for the characterization of which the crystal structure, physical properties, and mechanical strength of the composite system has been observed. In addition, the analysis was synchronized from the derivation of reaction mechanisms and the presented kinetics trending-graphs. The influences of degradation and biocompatibility were illustrated from Porosity, Flexural Strength, and Compressive Strength of the specimens that were resulting of CaSO4 crystal structures within variations of added CaCO3.