Search results for "Fen"
showing 10 items of 3710 documents
Quimiosensores y quimiodosímetros para la detección de neurotransmisores
2019
La presente Tesis Doctoral titulada “Quimiosensores y quimiodosímetros para la detección de neurotransmisores” está centrada en el desarrollo de nuevos sistemas para la detección cromogénica y fluorogénica de moléculas biógenas, haciendo especial hincapié en el uso del fenómeno conocido como Emisión Inducida por Agregación (AIE) como mecanismo de transducción. Para ello, se han sintetizado y estudiado una serie de derivados del tetrafenileteno (TPE), compuesto que presenta propiedades AIE que pueden ser modificadas fácilmente gracias a la adecuada funcionalización del mismo. En el capítulo 3 se describe cómo, en derivados del TPE funcionalizados con anillos de triazol sustituidos con cadena…
Aroniju ogu fitoķīmiskā sastāva izvērtējums
2019
Aroniju ogu fitoķīmiskā sastāva izvērtēšana. Batarāga A. Zinātniskā vadītāja Asoc.prof. Dr. ķīm. Prikšāne A., konsultante Mg.ķīm. Valkovska V. Maģistra darbs, 76 lappuses, 46 attēli, 20 tabulas, 44 literatūras avoti. Latviešu valodā. Darbā analizēts aroniju ogu fitoķīmiskais sastāvs, nosakot kopējo fenolu, flavonoīdu saturu un antiradikālo aktivitāti. Lai pagatavotu analizējamos paraugus, izmantotas gan sasaldētas, gan ţāvētas ogas un kā ekstrahenti – 70 % etanola/ūdens, 10 % glicerīna/etanola un daţādu koncentrāciju un pH vērtību etanola/ūdens/HCl maisījumi. Pēc ultraskaľas veicinātas ekstrakcijas un 1 – 3 nedēļu ilgas macerācijastika noteikts kopējo fenolu saturs, izmantojot FolinCiocalte…
Latvijas teritorijā sastopamo parasto un lielziedu vīgriežu fitoķīmiskais izvērtējums
2018
Latvijas teritorijā sastopamo parasto un lielziedu vīgriežu fitoķīmiskais izvērtējums. Berga M., zinātniskais vadītājs docente Dr. ķīm. Ilva Nakurte, Bakalaura darbs, 47 lappuses, 26 attēli, 8 tabulas, 32 literatūras avoti, 1 pielikums. Latviešu valodā. Literatūras apskatā apkopota informācija par lielziedu vīgriezi un parasto vīgriezi; dažādiem ekstrakcijas veidiem, antioksidatīvām īpašībām un abu vīgriežu fitoķīmiskajām īpašībām. Veikts abu vīgriežu sugu fitoķīmiskā sastāva salīdzinājums. Bakalaura darba eksperimentālajā daļā pagatavoti vīgriežu ekstrakti, izmantojot dažādas ekstrakcijas vides un veidus. Izmantojot UV/VIS spektroskopiju, veikti lielziedu un parastās vīgriezes etanola, gli…
Mikrozaļumu ķīmiskais sastāvs atkarībā no fotoperioda audzēšanas laikā
2020
Literatūras apskatā ir aprakstīts augu ķīmiskais sastāvs un gaismas ietekme uz to. Apkopotas paraugu sagatavošanas un analīzes metodes. Darbā ir veikta četru dažādu ģiņšu mikrozaļumu diedzēšana pie 4, 8 un 12 stundu ilgiem fotoperiodiem. Spektrometriski ir noteikta kopējā hlorofila un karotenoīdu koncentrācija, kopējā polifenolu koncentrācija un antiradikālā aktivitāte augos. Noteica mikroelementu un makroelementu sastāvu augos ar ICP-MS metodi. Noteica brīvo aminoskābju koncentrāciju augos ar HPLC-MS metodi. Iegūtie dati salīdzināti savā starpā, kā arī tika salīdzināts ķīmiskais sastāvs atkarībā no fotoperioda.
Pattern of macrovascular invasion in hepatocellular carcinoma
2021
Background and aims: In patients with hepatocellular carcinoma (HCC), macrovascular invasion (MaVI) limits treatment options and decreases survival. Detailed data on the relationship between MaVI extension and patients' characteristics, and its impact on patients' outcome are limited. We evaluated the prevalence and extension of MaVI in a large cohort of consecutive HCC patients, analysing its association with liver disease and tumour characteristics, as well as with treatments performed and patients' survival. Methods: We analysed data of 4774 patients diagnosed with HCC recorded in the Italian Liver Cancer (ITA.LI.CA) database (2008-2018). Recursive partition analysis (RPA) was performed …
Spectrophotometric determination of ethiofencarb in waters by reaction with p-aminophenol
1993
An automatized procedure has been developed for the spectrophotometric determination of ethiofencarb in water by reaction with p-aminophenol after alkaline hydrolysis to obtain the corresponding phenol sulphone. The hydrolyzed samples are continuously introduced into different manifolds at the same time as 300 mg/l p-aminophenol, 0.004 mol/l KIO4 and 0.04 mol/l NaOH solutions. The absorbance is measured at 638 nm after a reaction time of 6 min in stop flow. This absorbance band corresponds to the indo dye obtained from the reaction between the phenol sulphone of ethiofencarb and the quinoneimine form of the p-aminophenol and it permits a matrix-free spectrophotometric determination of ethio…
Influence of gamma-aminobutyric acid on baclofen intestinal absorption.
1994
Since previous studies suggested that baclofen absorption in the rat middle intestine was inhibited by beta-alanine and therefore mediated, at least in part, by the beta-aminoacid carrier, we focused our new studies on the analysis of the possible inhibition of the drug by a gamma-aminoacid model compound, gamma-aminobutyric acid (GABA). A rat jejunum in situ study was undertaken in order to evaluate the effect of GABA on baclofen absorption and to establish the inhibition model. Assays using isotonic perfusion solutions of 0.5 mM baclofen with starting GABA concentrations ranging from 0 to 100 mM are reported. The results show that the absorption rate pseudoconstants of the drug decrease a…
Partially competitive inhibition of intestinal baclofen absorption by beta-alanine, a nonessential dietary aminoacid.
1991
In situ intestinal absorption of baclofen in the rat in the presence of beta-alanine has been investigated. Through the perfusion of 0.50 mM baclofen solutions containing variable concentrations of the aminoacid (from 5 to 100 mM), a partially competitive inhibition of baclofen absorption was characterized: absorption rate pseudoconstants of the spasmolytic drug decrease as beta-alanine concentration increases, until a limiting value is obtained (36.8 per cent of that found for baclofen alone). A computer method was developed in order to calculate parameters governing baclofen absorption in the presence of beta-aminoacid, with the following results: Vm = 11.22 mM h-1; Km = 7.42 mM; Ki = 2.4…
Evidence of competitive inhibition for the intestinal absorption of baclofen by phenylalanine
1996
Abstract Previous studies showed that the absorption of the antispastic drug baclofen, in the rat middle intestine, is inhibited by β-alanine, γ-aminobutyric acid (GABA) and leucine. It was concluded that baclofen intestinal transport was mediated, at least in part, by the β-, γ- and α-amino acid carriers. We therefore focused our next studies on the analysis of the possible inhibition of drug absorption by an aromatic α-amino acid model compound, phenylalanine. An in situ study in the rat small intestine was undertaken in order to evaluate the effect of phenylalanine on baclofen absorption and to establish the inhibition model. Assays using isotonic perfusion solutions of 0.5 mM baclofen w…
LATIN AMERICA AND ABYA YALA IN TEACHING SPANISH HISTORY: THE "DISCOVERY", THE CONQUEST AND CONTROVERSIES OF THE BLACK LEGEND
2019
RESUMO O trabalho explicita as representações contemporâneas da História da América no ensino de História na Espanha. Explicita e problematiza as configurações textuais e iconográficas que pretendem ensinar uma história do “descobrimento”, da conquista e da colonização da América. Usou-se a metodologia da pesquisa bibliográfica e de campo, com técnica de fichamento e observações analíticas de obras historiográficas contemporâneas, livros didáticos e lugares de memória (museus e monumentos históricos). Em relação aos manuais didáticos, foram selecionados e analisados 18 livros de ensino de História editados por seis editoras no período de 2000 a 2015. Analisou-se a história do “descobrimento…