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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.
11

Utveckling av HPLC-metoder för kvantifiering av nyckelkomponenter i en villkorad emulsion / Development of HPLC methods for quantification of key components in a conditional emulsion

Persson, Mikael January 2009 (has links)
Traditionally, rolling mills use emulsions based on a mixture of oil and water for lubrication. Since two years ago SAPA has been using (instead of oil) a synthetic lubricant so called conditional emulsion for hot-rolling of aluminum. This lubricant is water based and homogenous at ambient temperature, but switches to a two-phase system at heating above the cloud point. This project aims to validate and if necessary modify an existing HPLC method for quantifying two out of three key components (A, B and C) in the conditional emulsion. Attempts to develop a method to quantify the pH adjusting components, X and Y were also made. These two methods are required to optimize the lubricant. Due to the complexity of the components, it has been difficult to present a method for quantification, and HPLC with ELS detection was chosen after a long series of trials. Due to a few uncontrollable parameters the proposed analysis method has tendencies to be unstable. The column used is sensitive to changes in equilibrium and ELSD is also less sensitive and less reproducible than the commonly used UV-detector. While the proposed assay method shows somewhat large relative standard deviations the method has been shown to produce sufficiently precise and accurate data for the intended purpose. Development of a method for the pH-adjusting components X and Y was more difficult than expected. For some reason their difference in chemical properties does not show satisfying impact in the chromatograms. This method is still in its cradle and needs further development.
12

Characterization Of Skeletal Muscle Lipids In Obese Mice Lines

Aras, Ebru 01 September 2012 (has links) (PDF)
Obesity becomes an epidemic health problem in developing and developed countries, which arises due to stable life style and increase in the consumption of high fat diets. Obesity is generally accompanied with various clinical disorders, such as insulin resistance, type II diabetes, hypertension, dyslipidemia and cardiovascular diseases. This study aims to characterize and quantify different lipid classes in longissimus dorsi (LD) and quadriceps (Q) skeletal muscles of control (DBA/2J), obese Berlin fat mouse inbred (BFMI) and Berlin muscle mouse inbred (BMMI) lines, which display high fat and high muscle content, respectively. These mouse lines were special due to their phenotypes, especially BFMI lines, which displayed spontaneous and strong obesity. These lines, more specifically BFMI860 and BFMI861, were also special due to their possibility of being an animal model of cardiovascular diseases and metabolic syndrome, since they also displayed insulin resistance. For separation,identification and quantification of various lipids of these lines, a novel method was developed which gives better separation of main lipid classes via using high performance liquid chromatography (HPLC) coupled to an evaporative light scattering detector (ELSD). Addition of triethylamine (TEA) to the solvents being used, and altering the parameters of HPLC and ELSD instruments, and also the gradient elution, provided a better separation with an enhanced resolution. This method has been applied to the lipid extracts obtained from longissimus dorsi (LD) and quadriceps (Q) skeletal muscles of control (DBA/2J), obese Berlin fat mouse inbred (BFMI) and Berlin muscle mouse inbred (BMMI). In this method, a binary gradient elution composed of n-Hexane, isopropanol, methanol, acetic acid and triethylamine was applied to the samples. All interested lipid classes, namely triglyceride (TG), cholesteryl ester (CO), cholesterol (C), 1-oleoyl-rac-glycerol (MG), phosphatidylcholine (PC) and cardiolipin (CLPN), all of which have been known to have a role in obesity, insulin resistance, and cardiovascular diseases, were separated, identified and quantified via this novel method. According to the results, among BFMI lines, BFMI860 and BFMI861 lines and BMMI806, among BMMI lines, are worth to study obesity. Especially, the former ones may also become animal models for cardiovascular diseases and metabolic syndrome.
13

Otimização das condições de produção microbiológica de destruxinas por Beauveria felina / Optimal conditions for the microbial production of destruxins by Beauveria felina

Raquel Peres de Morais Urano 21 October 2010 (has links)
O fungo entomopatogênico Beauveria felina produz as destruxinas, hexadepsipeptídeos cíclicos que apresentam diversas atividades biológicas, como por exemplo: atividade inseticida, fitotóxica, citotóxica contra células tumorais, atividade antiviral contra o vírus da hepatite B, dentre outras. Devido à atividade inseticida das destruxinas, os fungos que as produzem têm grande importância econômica. Assim, o objetivo deste trabalho foi realizar a otimização das condições de crescimento e produção das destruxinas pelo fungo Beauveria felina utilizando diferentes meios de cultivo, a fim de se isolar destruxinas em maiores quantidades para a avaliação de seu potencial tóxico. Foram utilizados métodos de planejamento experimental e análise multivariada para a otimização das condições de crescimento, resultando em três condições ótimas de cultivo para cada um dos meios de cultura MF, PDB e SBD. Em todas as condições ótimas de cultivo foram observadas destruxinas conhecidas, desconhecidas e destruxinas que não foram isoladas anteriormente de Beauveria felina. O cultivo de Beauveria felina no meio PDB foi o que mais apresentou destruxinas desconhecidas (5). Em seguida foi realizada uma otimização das condições de análise cromatográfica de destruxinas por CLAD-DAD-DELE-EM e a validação deste método. Uma das frações obtidas do meio de cultura de Beauveria felina apresentou atividade vermífuga contra Haemonchus contortus. Duas de suas frações purificadas, P1 (destruxina Ed1 - m/z 625 e pseudodestruxina B ou pseudodestruxina C - isobáricas, m/z 669) e P7 (destruxina D ou hidroxihomodestruxina B ou roseotoxina C - isobáricas, m/z 623), foram ativas contra o carrapato bovino Rhipicephalus microplus. / The entomopathogenic fungus Beauveria felina produces destruxins, cyclic hexadepsipeptides which have several biological activities, such as insecticidal, phytotoxic, cytotoxic against tumor cells, antiviral activity against hepatitis B virus, among others. Because of the insecticidal activity of destruxins, fungi that produce them have a considerable economic importance. Therefore the aim of this study was to optimize the conditions for the growth of Beauveria felina and its production of destruxins by using different culture media, in order to isolate larger quantities for the evaluation of their toxic potential. Experimental design and multivariate analysis were used for the optimization of growth conditions, resulting in three conditions for optimum growth for each of the culture media MF, PDB and SBD. Both known and unknown destruxins were observed in each of the optimal conditions, along with destruxins that were not previously isolated from Beauveria felina. The cultivation of Beauveria felina in PDB was the one that showed the largest amount of unknown destruxins (5). We then carried out an optimization of the chromatographic analysis of destruxins by HPLC-PDA-ELSD-MS and the validation of this method. One of the fractions obtained from the culture medium of Beauveria felina showed anthelmintic activity against Haemonchus contortus, while two of its purified fractions, P1 (destruxin Ed1 - m/z 625 and pseudodestruxin B or pseudodestruxin C - isobaric m/z 669) and P7 (destruxin D or hydroxyhomodestruxin B or roseotoxin C - isobaric m/z 623), were active against the cattle tick Rhipicephalus microplus.
14

Evaluación del uso de la radiación microondas y del control de temperatura para la separación de componentes en alimentos por cromatografía de líquidos

Carballo Marrero, Silvia 08 June 2017 (has links)
No description available.
15

Contribution à l'étude phytochimique de Solidago virgaurea : application dans le domaine bucco-dentaire et étude de la variabilité phytochimique pour la création d'une filière / Contribution to the phytochemical study of Solidago virgaurea

Laurençon, Lise 12 April 2013 (has links)
Dans le but de valoriser la biodiversité végétale des Alpes-Maritimes, une plante commune dans cette région, Solidago virgaurea, a été sélectionnée pour son potentiel inhibiteur de la conversion levure-hyphe de Candida albicans, micro-organisme responsable d’infections bucco-dentaires de type candidose. Le fractionnement bioguidé de l’extrait aqueux a conduit à l’identification d’une famille de saponines particulièrement active. Parmi les onze saponines majoritaires caractérisées par RMN et HRMS, cinq se sont révélées être de nouvelles structures. Les tests biologiques ont néanmoins montré qu’elles n’étaient pas toutes actives contre la forme filamenteuse de C. albicans. Ces résultats ont conduit à une étude de la variabilité de la composition en saponines de plusieurs populations alpines de S. virgaurea. Trois méthodes de dosage des saponines ont été développées par HPLC et HPTLC. Les résultats ont démontré l'influence de différents facteurs sur la composition en saponines. Enfin, la composition globale de différents extraits de S. virgaurea a été étudiée dans le but d'identifier des activités biologiques complémentaires. Parmi les composés identifiés, trois nouveaux acides octulosoniques ont été caractérisés, aux côtés de trois composés phénoliques identifiés pour la première fois chez S. virgaurea. Les tests biologiques sur les extraits et fractions ont par ailleurs mis en évidence des activités antioxydante, anti-tyrosinase et inhibitrice de cellules cancéreuses in vitro. Ces tests devront être approfondis ultérieurement. / Toward the promotion of plant diversity of Maritime Alps, a common plant of the alpine area, Solidago virgaurea, was chosen to its inhibiting activity of Candida albicans yeast-hyphal conversion, a causal agent of opportunistic oral infections named candidiasis. In a first step, an aqueous extract of S. virgaurea was submitted to bioassay guided fractionation. This led to an active saponin-containing fraction from which eleven saponins were characterized by carrying out NMR experiments along with HRMS analyses. Five out of these were identified for the first time and bioassays showed that saponins activity varied according to the molecular structure of the compound. In a second step, the saponins composition of various S. virgaurea populations was studied qualitatively and quantitatively, using HPLC and HPTLC. Results demonstrated that saponins composition depends on various factors. Finally, the overall chemical composition of different S. virgaurea extracts was investigated searching for additional bioactivities. Among all the identified compounds, three new octulosonic acids were characterized and three phenolic compounds were found for the first time in S. virgaurea. Moreover, bioassays on extracts and fractions showed antioxidant, anti-tyrosinase activity and inhibition of cancer cell lines in vitro. Further bioassays have now to be completed. As a conclusion, this work was the starting point of an oral care product development and the setting-up of an innovative sector.
16

Étude des conditions de production et d'excrétion induite ou naturelle de métabolites par les microalgues / Study of conditions of production and excretion induced or natural metabolites by the microalgae

Donot, Florentin 18 April 2013 (has links)
Depuis plusieurs années, la recherche dans le domaine des bioénergies s'oriente de plus en plus vers l'utilisation des microorganismes (bactéries, levures, moisissures et microalgues) pour la production de biocarburants. Face au contexte actuel de développement durable, l'utilisation des microorganismes oléagineux photoautotrophes (cyanobactéries et microalgues) semble potentiellement plus intéressante d'un point de vue économique (énergie solaire) et environnemental (assimilation de CO2) malgré des productions plus faibles que celles des microorganismes oléagineux hétérotrophes (levures et moisissures). L'objectif général de ces travaux de thèse a donc été d'étudier l'accumulation de lipides neutres et d'hydrocarbures chez Botryococcus braunii race A (chlorophycée unicellulaire d'eau douce), sélectionnée pour son potentiel de production après une étude bibliographique et d'évaluer les mécanismes naturels d'exsudation de ces métabolites. Afin de fiabiliser la quantification et l'identification des composés lipidiques produits par la microalgue, des méthodes d'analyse qualitative et quantitative par HPLC ont été mises au point. Les résultats analytiques ont permis de montrer que les méthodes d'extraction et quantification décrites dans la littérature conduisaient à surévaluer la teneur en hydrocarbures synthétisés par la souche B. braunii Utex 572. Les études menées lors de ce travail de thèse ont également permis de déterminer l'impact des principaux facteurs abiotiques (milieu de culture, pH, CO2, intensité lumineuse, salinité) sur la production de biomasse, lipides neutres et hydrocarbures par B. braunii et d'en définir les conditions optimales. L'étude de la flore bactérienne naturellement présente dans les cultures de B. braunii en conditions non axéniques et de sa dynamique a montré que celle-ci n'avait pas ou peu d'impact sur la production de biomasse et de lipides neutres chez B. braunii dans les conditions de l'étude. L'application d'un stress oxydatif à une culture de B. braunii en phase stationnaire n'a pas engendré le phénomène de « milking » recherché mais a eu un impact positif sur l'accumulation de lipides intracellulaires et sur la synthèse de triglycérides. / Biofuels produced from vegetable oils or microbial cultures, are an alternative to fossil fuels that can reduce the human impact on the environment. For several years, research in the field of bioenergy is moving increasingly toward the use of microorganisms (bacteria, yeasts, fungi and microalgae) for the production of biofuels. In the current context of sustainable development, the use of photoautotrophic oleaginous microorganisms (cyanobacteria and microalgae) seems potentially more interesting economically (solar energy) and environmentally (CO2 assimilation) despite lower production rates than those of heterotrophic oleaginous microorganisms (yeasts and moulds). The overall objective of this thesis has been to study the accumulation of neutral lipids and hydrocarbons in the A-race Botryococcus braunii (unicellular green alga of freshwater), selected on its potential production after literature review, and to evaluate the mechanisms of natural exudation of these metabolites. To reliable quantification and identification of lipid compounds produced by microalgae, methods of qualitative and quantitative analysis by HPLC were developed. The analytical results have shown that the extraction and quantification methods described in the literature led to overestimate the amount of hydrocarbons synthesized by the strain B. braunii Utex 572. The studies in this thesis have also identified the impact of key abiotic factors (culture medium pH, CO2, light intensity, salinity) on biomass production, neutral lipids and hydrocarbons by B. braunii and to define the optimal conditions of production. The study of the bacterial flora naturally present in cultures of B. braunii under non axenic conditions and its dynamics showed that it had little or no impact on the production of biomass and neutral lipids in B. braunii in the conditions of the study. The application of oxidative stress to a culture of B. braunii at the stationary phase did not cause the sought phenomenon of "milking" but had a positive impact on the accumulation of intracellular lipid and triglyceride synthesis.
17

Desenvolvimento e validação de métodos por HPLC-DAD-ELSD para controle de qualidade químico do látex do caule e do fruto de mangaba (Hancornia speciosa Gomes)

Santos, Alan Diego da Conceição 27 February 2012 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work describes the development and application of analytical methods to establish parameters to the quality control of fruit and trunk latex of H. speciosa using High Performance Liquid Chromatography (HPLC) with diode array detect and evaporative light scattering detector (ELSD). As a first step chromatographic profile analytical method was developed and validated for the analysis of authentic sample of trunk latex of H. speciosa, and then the optimized method was used for the analysis of commercial samples of trunk latex sold in open markets from Sergipe, Brazil. The visual comparison of the chromatographic profiles of different samples of trunk latex allowed checking the authenticity and dissimilarities of chemical profiles of these samples. Seven chemical markers were purified by semi-preparative HPLC-DAD from the trunk latex of H. speciosa, the characterization by 1H, 13C NMR allowed the identification of the following substances cyclohexylethanoid glucoside cornoside, cyclohexylethanoid glucoside dihydrocornoside and (7,8)-treo-4,7,9,9 -tetrahydroxy-3,3 -dimethoxy-8-O-4 -neolignan-7-O-β-D-glucopyranoside. As a second step of our work chromatographic method for qualitative analysis of chemical markers lupeol, α-amyrin, β-amyrin e 3- β-O-acyl lupeol esters in the fruit latex of H. speciosa and in the mangaba commercial pulp was developed, the optimized method showed itself appropriate to the identification of such substances with adequate separation. In the end one analytical method for the quantification of the lupeol ester content in fruit latex and commercial pulp was developed and validated using the HPLC-DAD-ELSD. In the validation study were evaluated the figures of merit selectivity, linearity, limit of quantification and detection, precision, accuracy, stability and robustness according to the standards described in RE nº 899/03 (ANVISA). The quantification of lupeol ester by both detectors was significantly similar (259.44 μg/mg DAD and 269.58 μg/mg ELSD) with one coefficient of variation of 2.7%. This paper presents a contribution to the quality control of H. speciosa samples. / O presente trabalho apresenta o desenvolvimento e aplicação de métodos analíticos para o controle de qualidade do látex do fruto e do caule de H. speciosa Gomes utilizando cromatografia líquida de alta eficiência com os detectores de arranjo de diodos e evaporativo por espalhamento de luz (HPLC-DAD-ELSD). No primeiro momento, um método analítico para a obtenção do perfil cromatográfico foi desenvolvido e validado para a análise de uma amostra autêntica do látex do caule de H. speciosa; em seguida foi utilizado o método otimizado para a análise de amostras do látex do caule comercializadas em feiras livres do Estado de Sergipe. A comparação visual dos perfis cromatográficos das diferentes amostras do látex do caule permitiu averiguar a autenticidade e as dissimilaridades dos perfis químicos dessas amostras. Utilizando uma coluna semi-preparativa, sete marcadores químicos foram purificados a partir do látex do caule de H. speciosa; a caracterização por RMN 1H, 13C possibilitou a identificação das seguintes substâncias: ciclohexiletanóide glicosilado cornosídeo, ciclohexiletanóide glicosilado dihidrocornosídeo e (7,8)-treo-4,7,9,9 -tetrahidroxi-3,3 -dimetoxi- 8-O-4 -neolignana-7-O-β-D-glicopiranosídeo. No segundo momento, um método cromatográfico para análise qualitativa dos marcadores químicos lupeol, α-amirina, β-amirina e ésteres 3- β-O-acil lupeol no látex dos frutos de H. speciosa e em polpa comercial de mangaba foi desenvolvido. Por fim, um método analítico para a quantificação do teor de ésteres de lupeol em látex dos frutos de H. speciosa e em polpa comercial foi desenvolvido e validado utilizando HPLC-DAD-ELSD. No estudo da validação foram avaliadas as figuras de mérito seletividade, linearidade, limite de quantificação e detecção, precisão, exatidão, estabilidade e robustez conforme as normas descritas na RE nº 899/03 (ANVISA). A quantificação do teor de ésteres de lupeol por ambos os detectores se mostraram significativamente similares (259,44 μg/mg para o DAD e 269,58 μg/mg para o ELSD) com coeficiente de variação de 2,7 %. Este trabalho apresenta uma contribuição ao controle de qualidade de amostras de H. speciosa.

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