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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
501

Vzájemné působení záporných elektrod a iontových kapalin / Interaction of Negative Electrodes and Ionic Liquids

Mahdalová, Kateřina January 2017 (has links)
This work deals with electrolytes and ionic liquids for Li-ion batteries. Following interaction of electrolytes and ionic liquids to electrodes material. In the theoretical part attention is focused on the description of battery electrolytes and ionic liquids for lithium-ion batteries.
502

Stratégia eliminácie akrylamidu v cereálnych produktoch / A strategy of acrylamide elimination in cereal foods

Belková, Renáta January 2010 (has links)
Acrylamide is a carcinogenic substance generated in heat processed food stuff, where the temperature increases over 120 °C. The main acrylamide precursors are carbonyl compounds and the amino acid asparagine. In this diploma work, possible elimination strategies were observed in a bread matrix with an addition of inorganic salts into the basic powder formulation for home bread making. Samples were analyzed from the point of view of acrylamide content as well as their physico-chemical properties and sensory evaluation too. Results show, that the addition of inorganic salts hasn`t expected considerable elimination impact as in the case of model samples. It has been shown the importance of fermentation process, whereas was the amount of acrylamide in bread without yeast added almost 14times higher. The addition of CaCl2 in bread mixture improved the organoleptic quality of final product, as proved in sensory evaluation with simultaneus positive effect on acrylamide reduction in bread.
503

Studium hydratačního procesu anhydritových maltovin / Study of Hydration Process of Anhydrite Binders

Verner, Filip January 2017 (has links)
The presented work deals with the study of hydration processes anhydrite binders with external exciters. Work is divided into two parts. Conceptually is this work divided into two parts The theoretical part of study contains general theory of gypsum binders, anhydrite binders and research at the institude THD. In the experimental part deals with proposal of recipes, making of samples and subsequent determination of main technological tests and monitoring hydration process by the XRD and DTA analysis.
504

Étude du comportement de l’uranium et de l’iode dans le mélange de fluorures fondus LiF-ThF₄ à 650 °C / Study of uranium and iodine behavior in the molten fluorides LiF-ThF₄ at 650 ° C

Durán-Klie, Gabriela 25 September 2017 (has links)
Le Réacteur Nucléaire à sel fondu à spectre rapide (Molten Salt Fast Reactor, MSFR) est un concept innovant de quatrième génération développé par le CNRS depuis 2004 et actuellement étudié dans le cadre du projet européen SAMOFAR de H2020. Le MSFR fonctionne avec un combustible nucléaire liquide constitué d’un mélange de sels fluorures LiF-ThF₄-(UF₄/UF₃) (77,5-20-2,5) mol% fondus à haute température (700-900°C). Ce réacteur est particulièrement intéressant pour le cycle de combustible du thorium (²³²Th-²³³U). Ce concept propose un retraitement intégré du combustible nucléaire basé sur des méthodes pyrochimiques afin d’extraire la matière fissile et de séparer les actinides des produits de fission.Un schéma de traitement du sel combustible, proposé lors d’un précédent projet européen (EVOL, FP7), est basé sur les propriétés redox et acido-basiques des éléments produits par les réactions de fission et de capture ayant lieu dans le cœur du réacteur. La base d’évaluation de ce schéma a été dans un premier temps thermodynamique. Une validation expérimentale est actuellement en cours qui consiste à étudier le comportement chimique et électrochimique du sel fondu et des éléments qui y sont solubilisés. Les études précédentes sur les réacteurs sels fondus ne peuvent être utilisées que partiellement pour ce concept car la composition du sel du MSFR définie par le projet européen EVOL est différente en nature et composition des sels proposés jusqu’à présent pour ce type de réacteurs. Or, les coefficients de diffusion et d’activité dépendent des propriétés physico-chimiques du sel fondu (en particulier de la solvatation) et nous avons, lors d’études précédentes, montré que les propriétés de solvatation des sels fondus dépendent fortement de leur nature et de leur composition.Les objectifs de ce travail de thèse sont l’étude du mélange fondu LiF-ThF₄ et du comportement électrochimique de l’uranium et de l’iode dans ce mélange.L’étude électrochimique du comportement de l’uranium a montré la stabilité de deux espèces solubles (UF₄ et UF₃) de cet élément dans le milieu fondu et la possibilité de le réduire à l’état métallique. Ce point est d’importance car la co-existence de ces deux composés permettra de contrôler le potentiel du sel combustible dans le cœur du réacteur et de limiter les réactions de corrosion avec les matériaux de structure. Les coefficients d’activité de U(IV) et de U(III) ont été déterminés. Les valeurs obtenues montrent que la solvatation de l’uranium au degré d’oxydation (IV) par les ions fluorure est beaucoup plus importante que celle de l’uranium au degré (III), ce qui est en accord avec des observations ultérieures dans d’autres sels fluorures. Notre choix pour l’étude des produits de fission dans le sel combustible s’est porté sur l’iode. Dans le cœur du réacteur, la forme stable de l’iode est la forme halogénure soluble I- et dans le schéma général de traitement du sel combustible, il est prévu d’extraire l’iode par une étape de fluoration qui permet de produire le gaz I₂. Cette étude a montré la contribution d’une réaction chimique à l’oxydation des ions iodures en iode gazeux. Cette réaction chimique d’oxydo-réduction correspond à l’oxydation des ions iodures par l’oxygène. Cette réaction n’est expliquée que par l’existence d’un oxyfluorure de thorium soluble ThOF₂. Une efficacité d’extraction de I₂ (g) supérieure à 95 % a été obtenue par électrolyse à potentiel contrôlé. Ces électrolyses, qui simulent la fluoration, permettent de valider l’étape d’extraction de l’iode dans le schéma de traitement.Ce travail de recherche a permis d’acquérir une meilleure connaissance de la stabilité du sel et du comportement chimique et électrochimique de différents composés (U et I) dans le sel. / The Molten Salt Fast Reactor (MSFR) is an innovative concept of GEN IV developed by the CNRS since 2004. It is currently studied in the framework of the European project SAMOFAR of H2020. The MSFR operates with a liquid nuclear fuel consisting of a mixture of fluoride salts LiF-ThF₄- (UF₄ / UF₃) (77.5-20-2.5) mol% melted at high temperature (700-900° C). This reactor is particularly advantageous for the thorium fuel cycle (²³²Th-²³³U). This concept proposes an integrated reprocessing of the nuclear fuel based on pyrochemical methods in order to extract the fissile material and to separate the actinides from the fission products.A scheme for the treatment of the fuel salt, proposed in a previous European project (EVOL, FP7), is based on the redox and acido-basic properties of the elements produced by the fission and capture reactions occurring in the reactor core. The baseline for this scheme was initially thermodynamic. Experimental validation is currently under way to study the chemical and electrochemical behavior of the molten salt and the elements solubilized therein. Previous studies on molten salt reactors can only be partially used for this concept because the composition of the MSFR salt defined by the European EVOL project is different from the composition of the salts proposed up to now for this type of reactor. However, the diffusion and activity coefficients depend on the physicochemical properties of the molten salt (in particular solvation) and in previous studies we have shown that the solvation properties of molten salts are strongly dependent on their nature and their composition.The objectives of this thesis are the electrochemical characterization of the molten mixture LiF-ThF₄ and the study of the electrochemical behavior of uranium and iodine.The electrochemical study of the behavior of uranium shows the stability of two soluble species (UF₄ and UF₃) of this element in the molten medium and the possibility of its reduction to the metallic state. This point is important because the co-existence of these two compounds will make possible to control the potential of the fuel salt in the core of the reactor in order to limit the corrosion reactions with the structural materials. The activity coefficients of U (IV) and U (III) were determined. The values obtained show that the solvation of uranium to the degree of oxidation (IV) by fluoride ions is much greater than that of uranium to degree (III), which is in agreement with subsequent observations in other fluoride salts.Our choice for the study of fission products in the fuel salt has focused on iodine. In the core of the reactor, the stable form of the iodine is the soluble halide form I- and in the general scheme of treatment of the fuel salt, it is planned to extract iodine by a fluorination step in order to produce the gaseous compound I₂. The electrochemical study shows the contribution of a chemical reaction to the electrochemical oxidation of iodide ions in gaseous iodine. This redox chemical reaction corresponds to the oxidation of the iodide ions by oxygen. This reaction is explained for the existence of a soluble thorium oxifluoride ThOF₂. Extraction efficiencies of I₂ (g) greater than 95% were obtained by electrolysis at controlled potential. These electrolysis, which simulate fluorination process, make it possible to validate the method for the extraction of the iodine in the reprocessing scheme.This research has led to a better understanding of salt stability and of the chemical and electrochemical behavior of several compounds (U and I) in the molten salt.
505

Cytotoxic Effects of Nickel Nanowires in Human Fibroblasts

Felix Servin, Laura P. 04 1900 (has links)
There is an increasing interest for the use of nanostructures as potential tools in areas that include biology and medicine, for applications spanning from cell separation to treatments of diseases. Magnetic nanoparticles (MNPs) have been the most widely studied and utilized nanostructures in biomedical applications. Despite their popularity, the regular shape of MNPs limits their potential for certain applications. Studies have shown that magnetic nanowires (MNWs), due to their high-­-aspect ratio and specific magnetic properties, might provide improved performance for some biomedical applications. As a consequence, MNWs have received increasing attention from researchers in the last years. However, as with any other nanostructure intended for biomedical applications, rigorous studies must be carried out to determine their potential toxicity and adverse effects before they can be successfully incorporated in clinical applications. This work attempts to elucidate the cytotoxic effects of nickel NWs (Ni NWs) in human fibroblasts by measuring cell viability under different parameters. Ni NWs of three different lengths (0.86 ± 0.02 μm, 1.1 ± 0.1 μm and 6.1 ± 0.6 μm) were fabricated by electrodeposition using porous aluminum oxide (PAO) membranes as templates. Energy dispersive X-­-Ray analysis (EDAX) and X-­-Ray diffraction (XRD) were used for the chemical characterization of the Ni NWs. Their physical characterization was done using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging. MTT assays were performed to assess cell viability of human fibroblasts in the presence of Ni NWs. NW length, NW/cell ratio and exposure time were changed throughout the experiments to elucidate their effects on cell viability. The results showed that NWs length has a strong effect on internalization and cytotoxicity. Smaller NWs showed higher toxicity levels at earlier times while longer NWs had stronger effects on cell viability at later times. NW/cell ratio did not seem to have a very strong effect at low concentrations. However, at high concentration (1000 NW/cell) significant loss of cell viability was observed, with the effects becoming stronger at later times. Other factors such as cell surface area, presence of oxide layer on NWs, and the cytotoxicity of Ni salts, were also studied and found to affect cell viability. For our knowledge, this is the first systematic study done in human fibroblasts wi-­-38 using ferromagnetic NWs; where the toxic effects of equivalent amounts of Ni in its salt and in its NW form are compared. It is also the first study to provide insights of the interaction between wi-­-38 cells and Ni NWs. The results of this study complement and enrich previous cytotoxicity studies of Ni NWs. This work aims at providing a more comprehensive understanding of the interaction between NWs and biological systems. Despite the advancements, further studies will be required to fully understand the factors affecting NW cytotoxicity. Only when we understand the underlying mechanisms, will we be able to design suitable nanostructures for biomedical applications.
506

Pharmacokinetics of individual versus combined exposure to "bath salts" compounds MDPV, Mephedrone, and Methylone

Troglin, Courtney G, Bouldin, J. Brooke, Schreiner, Shannon, Perez, Emily, Brown, Stacy D., Ph.D, Pond, Brooks B., Ph.D 12 April 2019 (has links)
Earlier this decade, “bath salts” were popularized as legal alternatives to the pyschostimulants cocaine and the amphetamines. These products contained synthetic cathinones including 3,4-methylenedioxypyrovalerone (MDPV), 4-methylmethcathinone (mephedrone), and 3,4-methylenedioxymethcathinone (methylone). Studies indicate that the cathinones have similar pharmacology to controlled psychostimulants, increasing levels of dopamine (DA) in the synaptic cleft. Most preclinical investigations have only assessed the effect of these synthetic cathinones independently; however, case reports and DEA studies indicate that “bath salts” often contain mixtures of these substances. Therefore, in a recent study by our laboratory, we examined effects of individual versus combined exposure to MDPV, mephedrone, and methylone. Interestingly, an enhanced effect on the levels of DA was observed, as well as significant alterations in locomotor activity following co-exposure to the cathinones. In this study, we examine whether the enhanced effects of the drug combination were due to pharmacokinetic (PK) interactions. It is known that many of the same cytochrome P450 (CYP) isoenzymes metabolize each of these three drugs. Therefore, it is probable that the drugs’ PK would differ when administered individually as compared to in combination. We hypothesize that combined exposure to MDPV, mephedrone, and methylone will result in increased drug concentrations and enhanced total drug concentrations when compared to individual administration. The pharmacokinetics of MDPV, mephedrone, and methylone in the brain and plasma were examined following intraperitoneal injection in mice. Briefly, adolescent male Swiss-Webster mice were injected intraperitoneally with either 10 mg/kg MDPV, 10 mg/kg mephedrone, 10 mg/kg methylone, or 10 mg/kg combined MDPV, mephedrone, and methylone. Following injection, brains and plasma were collected at the following time points: 1, 10, 15, 30, 60, and 120 minutes. Samples were then flash-frozen and stored at -70°C until analysis. Drugs were extracted via solid-phase extraction and concentrations were determined using a previously validated and published high pressure-liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Following intraperitoneal administration, all drugs quickly crossed the blood-brain barrier and entered the brain. Peak drug concentrations, time to peak concentration, drug half-lives, and total drug exposure (as measured by area under the curve) are compared when drugs were given individually versus in combination. These data provide insight into the consequences of co-exposure to popular “bath salt” products.
507

IMPACTS OF ROAD DE-ICING SALTS ON MANGANESE TRANSPORT TO GROUNDWATER IN ROADSIDE SOILS

Wen, Yingrong January 2012 (has links)
Manganese (Mn) is an important element in soil, it occur natural in minerals and precipitated as Mn-oxides. Several factors could decide the solubility and mobility of Mn in soil water. In this study, the impact of road de-icing salts (NaCl) on manganese mobilization and transport to groundwater in roadside soils has been investigated by leaching tests. Generally, in the salt solution leachates, the water-soluble concentrations of Mn tended to increase with elevated salt concentrations, suggesting that ion exchange mainly affected the mobilization. The process was also attributed to the complexion with Cl. Associated with exchangeable concentration of Mn and soil properties such as pH and acidity, the mobilizations of Mn varied. Mn-oxides can dissolve when reduced condition exists, therefore the oxalate extractable Mn was extracted to estimate the change of redox potential condition in roadside soils. The redox potential of soil samples is higher in general. Redox condition has little effect on the Mn solubility and mobility in this research. Although groundwater samples indicated that only a few periods and sites were under threaten of elevated concentrations of manganese, there is still great risk of transport of high water-soluble concentrations of Mn in roadside soils to groundwater, especially the areas exposed to de-icing salts. In addition, lower value of Mn concentrations in groundwater for considering good drinking water quality for the well-being of children should be paid more attention to.
508

Extraction of Mn and Cr from slags by molten salt electrolysis

Tianming, Sun January 2012 (has links)
There are many kinds of elements, especially heavy metallic elements, presentin the industrial slags. These elements bring big environmental problems ifthey are directly used in land filling. And the recovery of these elements canalso have benefits for the resource conservation. This paper reports the use ofelectrochemical method to extract the metal elements from both industrial slagand pure oxide. The mixture of NaCl-KCl was used as the electrolyte for thisprocess. Some proposals are alsomentioned for the further work.
509

Lethal and Toxic Effects of Synthetic Cathinone Analogues at Physiologically Preferred and High Temperatures

Heeren, Sasha January 2021 (has links)
No description available.
510

Deaths Involving Methylenedioxypyrovalerone (MDPV) in Upper East Tennessee

Wright, Trista H., Cline-Parhamovich, Karen, Lajoie, Dawn, Parsons, Laura, Dunn, Mark, Ferslew, Kenneth E. 01 November 2013 (has links)
Two deaths involving 3, 4-methylenedioxypyrovalerone (MDPV) are reported. MDPV is a synthetic cathinone stimulant found in "bath salts" with neurological and cardiovascular toxicity. Biological specimens were analyzed for MDPV by GC/MS and LC/MS. A White man was found dead with signs of nausea and vomiting after repeatedly abusing bath salts during a weekend binge. Femoral venous blood and urine had MDPV concentrations of 39 ng/mL and 760 ng/mL. The second fatality was a White man with a history of drug and bath salt abuse found dead at a scene in total disarray after exhibiting fits of anger and psychotic behavior. Femoral venous blood and urine had MDPV concentrations of 130 ng/mL and 3800 ng/mL. The blood and urine MDPV concentrations are within the reported recreational concentration ranges (blood 24-241 ng/mL and urine 34-3900 ng/mL). Both decedents' deaths were attributed to relevant natural causes in a setting of MDPV abuse.

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