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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.
201

Análise de variação populacional e caracterização dos metabólitos secundários presentes nas folhas de Lychnophora granmongolense (Duarte) Semir & Leitão Filho / Analysis of populational variation and characterization of secondary metabolites in the leaves of Lychnophora granmongolense (Duarte) Semir & Leitão Filho.

Ferreira, Leandro de Santis 28 April 2010 (has links)
Uma das principais características da família Asteraceae é sua capacidade de produzir uma grande diversidade de metabólitos secundários que podem possuir efeitos terapêuticos ou tóxicos. Para verificar a existência de variações inter e intrapopulacionais na sua composição metabólica secundária de Lychnophora granmongolense (Duarte) Semir & Leitão Filho e caracterização desses metabólitos foi desenvolvida uma metodologia analítica em CLAE DAD. Essa metodologia permitiu a identificação de três compostos, vicenina-2, quercetina e pinocembrina, através da coinjeção de padrões, ou seja, pela comparação do tempo de retenção com padrões previamente isolados associados com os dados do espectro no UV. Com a utilização da técnica de espectrometria de massas, CLAE-DAD-EM e CLAE-DAD-EM/EM, foram identificadas quatro lactonas sesquiterpênicas (LST), centraterina, 4,5-di-idrocentraterina, lychnofolido e 15-desoxigoyazensolido. No estudo de variação populacional, os resultados indicaram grandes variações quantitativas e qualitativas tanto inter quanto intrapopulacionais para os metabólitos de alta e média polaridade. A análise dos metabólitos mais apolares presentes nas folhas permitiu a identificação de 8 triterpenos e 8 triterpenos acetilados. Contudo, esses metabólitos apresentam somente pequena variação que não é significativa. Assim, esse estudo contribuiu para o aumento do conhecimento sobre o ritmo metabólico dessa espécie. / One of the main characteristics of plants of the Asteraceae family is their capacity to produce a huge diversity of secondary metabolites having therapeutic and toxic effects. An analytical method was developed based on HPLCDAD which was used to verify the existence of variations in Lychnophora granmongolense (Duarte) Semir & Leitão Filho secondary metabolite levels among species within populations and between distinct populations and to characterize the major secondary metabolites. Through this method three compounds, namely vicenin-2, quercetin and pinocembrin were identified by co-injection of standards. This identification was based on the comparison of retention time with isolated standards and the UV spectrum. Four sesquiterpenes lactones centratherin, 4,5-dihydrocentratherin, lycnopholide and 15-deoxygoyazensolide were identified by mass spectrometry techniques coupled with HPLC (HPLC-DAD-MS e HPLC-DAD-MS/MS). In the populational variation study, the results show large qualitative and quantitative differences among species within populations and between populations for high and medium polarity secondary metabolites. Eight triterpenes and eight acetyl triterpenes were identified by apolar compound analysis. However, small, insignificant variation was observed for these particular metabolites. Thus, this study contributed to an increase in the knowledge of the metabolic rhythm of this specie.
202

Antigens derived from the mucin MUC1 : Solution and solid-phase synthesis of saccharides, peptides and glycopeptides

Pudelko, Maciej January 2008 (has links)
Mucin is a term used to describe a large family of heavily glycosylated proteins which are present on the surfaces of secretory epithelial cells and are overexpressed by many carcinomas. Membrane-bound mucin MUC1 is of special interest. Its backbone consists of repeating units of twenty amino acids with five potential glycosylation sites. These sites are expanded to structures like the T (Galβ(1->3)GalNAcα-Ser/Thr) and Tn (GalNAcα-Ser/Thr) antigens by the action of various glycosyltransferases. In different types of carcinomas these epitopes are being terminated by sialic acid residues to form among others: 2,3-sialyl-T and sialyl-Tn structures due to the elevated levels of different sialyltransferases. Solid-phase synthesis of the selected antigens derived from the mucin MUC1 has been developed and optimized. A chemoenzymatic approach has been used to effectively prepare 2,3-sialyl-T and 2,6-sialyl-Tn glycopeptides. The formation of intramolecular sialic acid lactones in presence of acetic acid was investigated. The stability of lactones formed from 2,3-sialyl-T towards water was studied using NMR spectroscopy and it appeared that 1''->2' lactone displayed remarkable strength to hydrolysis and it was suggested as a candidate for cancer vaccine. Gel-phase 19F NMR spectroscopy is known to be a very good tool to characterize resin-bound products using fluorinated protecting groups and linker molecules. The hydrophobic peptide LLLLTVLTV, which is a fragment from the MUC1 signal sequence, was prepared using solid-phase synthesis according to a modified Fmoc protocol with more active coupling reagent, stronger base, and the isopropylidene dipeptide Fmoc-Leu-Thr-(ΨMe,Mepro)-OH. Gel-phase 19F NMR spectroscopy was used to evaluate peptide chain aggregation and coupling and deprotection efficiency. A carbamate linker strategy proved to be effective in solid-phase synthesis of serine-based neoglycolipids with terminal amino functionality. Neoglycolipids were covalently bound to secondary amines in microtiter plates using squaric acid ester methodology. These arrays have potential to study the interactions between carbohydrates and e.g. proteins and microbes. The new fluorinated α-amino protective group [1-(4-(4-fluorophenyl)-2,6-dioxocyclohexylidene)ethyl] Fde was developed. This group is cleaved with hydrazine in DMF solution. By using amino acids protected with this group, it was possible to quantify the efficiency of peptide coupling using gel-phase 19F NMR spectroscopy.
203

Estudio de la función de la familia de Proteínas Quinasas C en el cáncer de mama

López Nicolás, Rubén 11 February 2011 (has links)
En esta Tesis Doctoral se ha estudiado el efecto de una serie de ácidos grasos como el araquidónico, docosahexaenoico, eicosapentaenoico y oleico, así como un conjunto de derivados de DAG-lactonas en la activación de diferentes isoenzimas de PKC. El sistema modelo de estudio utilizado han sido diferentes líneas celulares de cáncer de mama (BT-474, MCF-7 y MDA-MB-231). Mediante técnicas de biología molecular y celular, microscopía confocal, ARN de interferencia y microarrays de expresión diferencial de genes se ha estudiado la función de la PKCalpha en la capacidad proliferativa, invasiva y de migración de las células modelo de cáncer de mama, revelando nuevos mecanismos moleculares por los que la PKCalpha se localiza en la membrana plasmática y se activa en dichas células. También se pone de manifiesto el efecto antiproliferativo e inductor de apoptosis de los diversos ácidos grasos estudiados, así como la implicación directa de la PKCalpha en la capacidad proliferativa, migr atoria e invasiva de dichas células / In this Doctoral Thesis, the role of several fatty acids like arachidonic, docosahexaenoic, eicosapentaenoic and oleic, as well as some DAG-lactones derivatives, on the activation of different PKC isoforms has been studied. Some breast cancer cell lines, specifically BT-474, MCF-7 and MDA-MB-231, have been used as a model. The role of PKC in proliferation, invasion and migration has been studied by means of cellular and molecular techniques, confocal microscopy, siRNA and gene expression microarrays. The results obtained reveal new molecular mechanisms of PKCalpha; localization and activation in breast cancer cell lines. It is also interesting the anti-proliferative and pro-apoptosis role of several fatty acids tested, as well as the direct involvement of PKCalpha; in proliferation, migration and invasion of breast cancer cells
204

Implications des N-acyl homosérine lactones, molécules du quorum sensing dans les maladies inflammatoires chroniques intestinales / Involvement of N-acyl homoserine lactones, quorum sensing molecules, in inflammatory bowel diseases

Landman, Cécilia 28 November 2017 (has links)
Les N-acyl homosérine lactones sont des molécules du quorum sensing impliquées dans la communication interbactérienne mais elles sont également capables d'intéragir avec les cellules eucaryotes. Rechercher ces molécules dans le contexte des maladies inflammatoires chroniques intestinlaes (MICI) et plus particulièrement dans le cadre de l'étude des conséquences de la dysbiose sur les voies de l'inflammation intestinale est séduisant. En utilisant la spectrométrie de mase, nous avons mis en évidence pour la première fois des AHLs dans l'écosystème intestinal humain, et plus particulièrement une nouvelle AHL, 3-oxo-C12 :2, qui est prédominante. Cette AHL est corrélée à la normobiose, est perdue au cours des MICI et exerce un effet protecteur sur les cellules épithéliales intestinales. En effet, la 3-oxo-C12 :2 exerce un effet anti-inflammatoire in vitro sur les cellules Caco-2 sans augmenter la perméabilité paracellulaire. De plus, les premiers résultats in vivo montrent que la 3-oxo-C12 est également capable d'influencer la composition du microbiote intestinal des souris. Ces résultats ouvrent de nombreuses perspectives notamment dans la recherche de traitements écologiques au cours des MICI. / Quorum sensing molecules N-acyl-homoserine lactones (AHLs) involved in bacterial communication network are also able to interact with eukaryotic cells. Searching for these molecules in the context of inflammatory bowel diseases (IBD) and more precisely when studying consequences of dysbiosis on gut inflammation pathways is appealing. Using mass spectrometry, we identified for the first time AHLs in human intestinal ecosystem, and among them a new AHL, 3-oxo-C12:2 which is prominent. This AHL correlates with normobiosis, is lost IBD and exerts protective effect on gut epithelial cells. In fact, 3-oxo-C12:2 exerts anti-inflammatory effect in vitro on Caco-2 cells without increased paracellular permeability. Furthermore, first results from in vivo experiments show that 3-oxo-C12:2 is also able to influence mice gut microbiota composition. These results open multiple perspectives especially on new ecological treatments in IBD.
205

Estudos de Docking Molecular, síntese e atividade biológica de análogos da (-)- massoialactona e da combretastatina A-4

BARROS, Maria Ester de Sá Barreto 01 May 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-04T13:49:10Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Maria Ester Barros_CD_4.pdf: 6351675 bytes, checksum: 1634d753cabb911bd4c0cf8e58182237 (MD5) / Made available in DSpace on 2017-04-04T13:49:10Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese Maria Ester Barros_CD_4.pdf: 6351675 bytes, checksum: 1634d753cabb911bd4c0cf8e58182237 (MD5) Previous issue date: 2015-05-01 / CNPQ / A primeira parte deste trabalho envolveu o estudo de docking molecular, a síntese, e a avaliação das atividades antitumorais e anti-inflamatórias de lactonas -insaturadas, análogos estruturais da (-)-Massoialactona, produto natural com conhecida atividade farmacológica. O alvo biológico selecionado para o estudo de docking foi a CRM-1, e tal estudo revelou o potencial biológico dos análogos propostos. Estes análogos foram sintetizados em rendimentos que variaram entre 65-75%, e as suas atividades antitumoral e anti-inflamatória foram avaliadas, sendo que um deles mostrou-se bastante promissor. Estudos posteriores de docking molecular da lactona mais promissora revelou que, apesar dos isômeros R e S assumirem diferentes encaixes no sítio ativo da CRM-1, não há diferença significativa na energia de ligação entre esses isômeros e o alvo molecular estudado. A segunda etapa deste trabalho envolveu o estudo de docking molecular, a síntese, e a avaliação da atividade antitumoral de Z-estilbenos, análogos da Combretastatina A-4 (CA-4). O alvo biológico selecionado para o estudo de docking molecular foi o domínio da colchicina na tubulina. Os cálculos teóricos dos análogos estruturais propostos revelaram que seis desses compostos apresentam diferenças significativas nos valores de energia de ligação quando comparados com o valor teórico calculado para a CA-4, ou seja, teoricamente seriam mais ativos que o produto natural. Dos análogos selecionados a partir do docking molecular, dois foram sintetizados em bons rendimentos empregando-se como precursores teluretos vinílicos e organotrifluoroboratos de potássio. A posterior avaliação da atividade antitumoral dos compostos sintetizados revelou que os resultados obtidos estavam em concordância com o previsto no estudo teórico. / The first part of this work involved the study of molecular docking, synthesis, and the evaluation of anti-tumor and anti-inflammatory activities of unsaturated-lactones, structural analogues of (-)-Massoialactone, a natural product with known pharmacological activity. The biological target selected for the docking study was the CRM-1 and this study revealed the biological potential of the proposed analogues. These analogues were synthesized in yields ranging from 65-75%, and its anti-tumor and anti-inflammatory activities were evaluated, being one of them very promising. Further studies of molecular docking using the most promising lactone revealed that despite the R and S isomers take different fittings in the active site of CRM-1, there is no significant difference in binding energy between these isomers and the molecular target studied. The second step of this work involved the study of molecular docking, synthesis, and evaluation of antitumor activity of Z-stilbenes, analogues of combretastatin A-4. The biological target selected for the study of molecular docking was the domain of colchicine in tubulin. Theoretical calculations of the proposed structural analogues revealed that six of these compounds shown significant differences in binding energy values compared to the theoretical values calculated for the CA-4, ie, theoretically, the proposed compounds would be more active than the natural product. From the selected analogs proposed by molecular docking, two were synthesized in good yields employing vinyl tellurides and potassium organotrifluoroborates as precursors. Further evaluation of the antitumor activity of the synthesized compounds showed that the results were in agreement with the theoretical study.
206

Estudos conformacionais de lactonas sesquiterpênicas e compostos relacionados / conformational study of sesquiterpene lactonas and related compounds

Alvaro Cunha Neto 23 August 2006 (has links)
Neste trabalho foram realizados estudos conformacionais de algumas lactonas sesquiterpenicas e cálculos teóricos de deslocamento químico. O estudo conformacional é dividido em tres etapas distintas. A primeira etapa se dá pela busca conformacional em mecânica molecular, onde foram encontradas as possíveis conformações assumidas pelo sistema em estudo. Na segunda etapa, as conformações encontradas foram otimizadas em mecânica quântica. O último passo neste estudo foi o cálculode deslocamento químico e a posterior correlação com os dados experimentais. / This work is aimed on the theoretical calculation of chemical shifts of sesquiterpene lactones, based on the conformational preferences of the compounds. This conformational study is set up in three stages. The first one is a conformational search using molecular mechanics, to assess the relevant conformations of the system under study. In the second stage, the conformations are optimized by quantum mechanics, for the refinement of both the structural assignment and energy calculation of the most stable conformers found in the previous step. The last step is the theoretical calculation of chemical shifts. Finally the weighted average of calculated values is compared to experimental data.
207

Atividade anti-diabética, anti-inflamatória e toxicologia de Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson - Asteraceae / Anti-diabetic, anti-inflammatory activities, and toxicology of Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson - Asteraceae.

Rejane Barbosa de Oliveira 11 April 2011 (has links)
Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson (Asteraceae), conhecida popularmente como yacón, é um erva utilizada na medicina popular para o tratamento do diabetes. A ação hipoglicemiante do extrato aquoso das folhas do yacón foi comprovada em estudos recentes realizados por outros autores em animais diabéticos. Análises fitoquímicas preliminares revelaram que a espécie é rica em lactonas sesquiterpênicas (LST) e em derivados dos ácidos clorogênicos (ACG). Ambas as classes de substâncias possuem inúmeras atividades biológicas, como ação antioxidante, anti-inflamatória, e inibidora de enzimas que podem contribuir no quadro de melhora do estado diabético. Contudo, ainda não está comprovado se as atividades biológicas da espécie são resultantes da ação dos ACG ou das LST. Adicionalmente, análises toxicológicas do consumo das folhas do yacón ainda não foram realizadas. Assim, o objetivo deste trabalho foi avaliar três extratos preparados com folhas do yacón, com o intuito de analisar o papel das diferentes classes químicas no desenvolvimento das atividades biológicas descritas para a espécie, bem como de seus potenciais efeitos tóxicos. Os extratos obtidos foram: o extrato aquoso (EA), no qual foram detectados tanto ACG (2,0 e 1,3 µg/mL dos picos mais intensos), quanto LST (99,7 e 319,0 µg/mL dos picos mais intensos); extrato de lavagem foliar (ELF), rico em LST (1257,4 e 1997,7 µg/mL das majoritárias) e o extrato polar (EP), rico em ACG (9,9 e 9,6 µg/mL dos picos mais intensos), mas sem LST. Os estudos toxicológicos demonstraram que o EP não causou efeitos tóxicos significativos em ratos, enquanto alterações em parâmetros bioquímicos específicos no sangue (creatinina 7,0 mg/dL, glicose 212,0 mg/dL, albumina 2,8 g/dL) de ratos tratados com o EA (10, 50 e 100 mg/kg) e ELF (10 e 100 mg/kg) apontaram para dano renal, confirmado por análises histológicas dos rins. Todos os extratos apresentaram atividade anti-edematogênica in vivo, em especial no modelo de edema induzido por óleo de cróton (EA: 25,9% inibição do edema a 0,5 mg/orelha; EP: 42,7% de inibição a 0,25 mg/orelha, ELF: 44,1% de inibição a 0,25 mg/orelha). O ELF demonstrou os melhores resultados na inibição da migração de neutrófilos, na indução da IL-10, na inibição do NO, TNF- e PGE2, quando comparado aos demais extratos. Todos os extratos inibiram de forma estatisticamente similar a atividade da -amilase, enquanto o EA e o EP foram mais eficazes na redução dos níveis glicêmicos após a administração oral de glicose (controle glicêmico: 201,8±5,2, EA: 169,0±4,9, EP: 176,7,3±7,3, ELF: 219,1±7,6 mg/dL). Com os dados obtidos neste trabalho pode-se concluir que o consumo do chá das folhas do yacón por períodos prolongados pode ser tóxico e seu uso não deve ser recomendado na medicina popular. As LST parecem ser as substâncias responsáveis por essa toxicidade. Tanto as LST, quanto os ACG contribuem para atividade anti-inflamatória, embora as LST parecem ter efeitos mais pronunciados. Contudo, a atividade anti-diabética da espécie parece estar relacionada principalmente à presença ao ACG e não à LST, sendo necessários estudos mais detalhados com ACG puros para verificar seu uso potencial no tratamento do diabetes. / Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson (Asteraceae), known as yacón is a herb used in folk medicine to treat diabetes. The hypoglycaemic effect of the aqueous extract from yacón leaves was demonstrated in recent studies in diabetic animal models. Phytochemical analyzes have demonstrated that this species is rich in chorogenic acids (CGAs) and sesquiterpene lactones (STLs). Both classes of compounds have many biological activities such as antioxidant, anti-inflammatory and inhibit enzymes that can contribute in the improvement of the diabetic state. However, it is not yet established whether the biological activities of this species are due to the action of the CGAs or STLs. In addition, toxicological analysis of the consumption of yacón leaves has not yet been performed. Thus, the purpose of this study was to evaluate three extracts prepared from leaves of yacón, with the aim to analyze the role of different chemical classes in the development of the biological activities described for this species, as well as their potential toxic effects. The following extracts were obtained: aqueous extract (AE), were detected CGAs (2.0 and 1.3 mg / mL of the more intense peaks), and STLs (99.7 and 319 mg / mL of most intense peaks); leaf rinse extract (LRE), rich in STLs (1257.4 and 1997.7 mg / mL of major peaks), and the polar extract (PE) rich in CGAs (9.9 and 9.6 mg / mL of the more intense peaks), but without STLs. The toxicological studies in animals showed that the PE did not cause significant toxic effects, while changes in specific biochemical parameters in blood (creatinine 7.0 mg / dL, glucose 212.0 mg / dL, albumin 2.8 g / dL) of rats treated with AE (10, 50 and 100 mg / kg) and LRE (10 and 100 mg / kg) indicated kidney damage, which was confirmed by histological analysis of kidneys. All extracts showed anti-oedematogenics activity in vivo, particularly in the model of oedema induced by croton oil (AE: 25.9% of oedema inhibition at 0.5 mg / ear, PE: 42.7% of inhibition at 0.25 mg / ear, LRE: 44.1% inhibition at 0.25 mg / ear). The LRE showed the best results in the inhibition of neutrophil migration, induction of IL-10, as well as NO, TNF- and PGE2 inhibition, when compared to other extracts. All extracts inhibited in a statistically similar way the activity of -amylase, while the AE and the PE were more effective in reducing blood glucose levels after oral glucose adminstration (glycaemic control: 201.8 ± 5.2; AE: 169, 0 ± 4.9; PE: 7.3 ± 176,7,3; LRE: 219.1 ± 7.6 mg / dL). The data obtained in this work suggested that the consumption of tea from yacón leaves for prolonged periods can be toxic and their use should not be recommended in folk medicine. The STLs seem to be the substances responsible for this toxicity. Both STLs and CGAs contribute to the anti-inflammatory activity, although the STLs seem to have more pronounced effects. However, the anti-diabetic activity of the yacón leaves seems to be related to the presence of the CGAs and not to LST. More detailed studies with pure CGAs are required in order to determine their potential use in treatment of diabetes.
208

Thiol−ene Coupling of Renewable Monomers : at the forefront of bio-based polymeric materials

Claudino, Mauro January 2011 (has links)
Plant derived oils bear intrinsic double-bond functionality that can be utilized directly for the thiol–ene reaction. Although terminal unsaturations are far more reactive than internal ones, studies on the reversible addition of thiyl radicals to 1,2-disubstituted alkenes show that this is an important reaction. To investigate the thiol–ene coupling reaction involving these enes, stoichiometric mixtures of a trifunctional propionate thiol with monounsaturated fatty acid methyl esters (methyl oleate or methyl elaidate) supplemented with 2.0 wt.% Irgacure 184 were subjected to 365-nm UV-irradiation and the chemical changes monitored. Continuous (RT– FTIR) and discontinuous (NMR and FT–Raman) techniques were used to follow the progress of the reaction and reveal details of the products formed. Experimental results supported by numerical kinetic simulations of the system confirm the reaction mechanism showing a very fast cis/trans-isomerization of the alkene monomers (<1.0 min) when compared to the total disappearance of double-bonds, indicating that the rate-limiting step controlling the overall reaction is the hydrogen transfer from the thiol involved in the formation of final product. The loss of total unsaturations equals thiol consumption throughout the entire reaction; although product formation is strongly favoured directly from the trans-ene. This indicates that initial cis/trans-isomer structures affect the kinetics. High thiol–ene conversions could be easily obtained at reasonable rates without major influence of side-reactions demonstrating the suitability of this reaction for network forming purposes from 1,2-disubstituted alkenes. To further illustrate the validity of this concept in the formation of cross-linked thiol–ene films a series of globalide/caprolactone based copolyesters differing in degree of unsaturations along the backbone were photopolymerized in the melt with the same trithiol giving amorphous elastomeric materials with different thermal and viscoelastic properties. High thiol–ene conversions (>80%) were easily attained for all cases at reasonable reaction rates, while maintaining the cure behaviour and independent of functionality. Parallel chain-growth ene homopolymerization was considered negligible when compared with the main coupling route. However, the comonomer feed ratio had impact on the thermoset properties with high ene-density copolymers giving networks with higher glass transition temperature values (Tg) and a narrower distribution of cross-links than films with lower ene composition. The thiol–ene systems evaluated in this study serve as model example for the sustainable use of naturally-occurring 1,2-disubstituted alkenes at making semi-synthetic polymeric materials in high conversions with a range of properties in an environment-friendly way. / Vegetabiliska oljor som innehåller dubbelbindningar kan användas direkt för thiolene reaktioner. Trots att terminala dubbelbindningar är mycket mer reaktiva än interna visar dessa studier att den reversibla additionen av thiyl radikaler till 1,2-disubstituerade alkener är en viktig reaktion. För att undersöka tiol–ene reaktionerna, som ivolverar dessa alkener förbereddes stökiometriska blandningar av en trifunktionell propionat tiol och enkelomättade fettsyrametylestrar (metyloleat eller metyl elaidat) samt 2.0 vikt.% Irgacure 184. Dessa blandningar utsattes för 365-nm UV strålning och de kemiska förändringarna studerades. De kemiska förändringarna analyserades med olika kemiska analysmetoder; realtid RT–FTIR, NMR och FT–Raman. Dessa användes för att analysera de kemiska reaktionerna i realtid och följa bildandet av produkterna. Reaktionsmekanismen bekräftades med hjälp av experimentella data och beräkningar av numeriska och kinetiska simuleringar för systemet. Resultaten visar en mycket snabb cis/trans-isomerisering av alkenmonomeren (<1.0 min) jämfört med den totala förbrukningen av dubbelbindningarna, vilket indikerar att det hastighetsbegränsande steget kontrolleras av väteförflyttningen från tiolen till slutprodukten. Förbrukningen av den totala omättade kolkedjan är lika med tiolförbrukningen under hela reaktionen, även om bildandet av produkten gynnas från trans-enen. Detta indikerar att den första cis/trans-isomerstrukturen påverkar kinetiken. Höga tiol-ene utbyten kan enkelt erhållas relativt snabbt utan inverkan av sidoreaktioner. Detta innebär att denna reaktion kan användas som nätverksbildande reaktion för flerfunktionella 1,2-disubstituted alkenmonomerer. Vidare användes fotopolymerisation i smälta på en serie globalid/kaprolaktonbaserade sampolyestrar med varierad grad av omättnad med samma tritiol vilket resulterade i bildandet av amorfa elastomeriska material med olika termiska och viskoelastiska egenskaper. Hög omsättning (>80%) uppnåddes relativt enkelt för samtliga blandningar oberoende av den initiala funktionaliteten. Homopolymerisation av alkenen var försumbar i jämförelse med den tiol–en-reaktionen. Mängden alkengrupper har inverkan på härdplastsegenskaperna där en hög andel alken ger en nätstruktur med högre glastransitionstemperatur (Tg). Tiol–ene reaktionen utvärderades i modellsystem baserade på naturlig förekommande 1,2-disubstituterade alkener för att demonstrera konceptet med tiol-förnätade halvsyntetiska material. / QC 20110915
209

Synthesis and Evaluation of Functionalized Dirhodium(II) Carboxylate Catalysts Bearing Axially Chiral Amino Acid Derivatives / 軸性不斉アミノ酸リガンドを有する官能基化されたロジウムカルボキシラート触媒の合成と反応開発

Wenjie, Lu 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(薬科学) / 甲第20303号 / 薬科博第72号 / 新制||薬科||8(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 川端 猛夫, 教授 高須 清誠, 教授 竹本 佳司 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DGAM
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Identification of Compounds that Impact the Ready-to-drink Coffee Flavor Stability during Storage Using LC-MS Flavoromics

Lin, Hao January 2021 (has links)
No description available.

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