Search results for "Reaction"

Hydrophobically directed aldol reactions: polystyrene-supported L-proline as a recyclable catalyst for direct asymmetric aldol reactions in the prese…

2007

A simple synthetic methodology for the preparation of a polystyrene- supported L-proline material is reported, and this material has been used as catalyst in direct asymmetric aldol reactions between several ketones and arylaldehydes to furnish aldol products in high yields and stereoselectivities. Screening of solvents showed that these reactions take place only in the presence of water or methanol, at lower levels of conversion in the latter case. This solvent effect, coupled with the observed high stereoselectivities, has been ex- Introduction In the last decade organocatalysis has became a field of great interest.[1] Organocatalysts are metal-free small organic molecules that are able t…

Peculiar mechanism of solubilization of a sparingly water soluble drug into polymeric micelles. Kinetic and equilibrium studies.

2012

Complementary kinetic and equilibrium studies on the solubilization process of the sparingly water soluble tamoxifen (TAM) drug in polymeric aqueous solutions have been performed by using the spectrophotometric method. In particular, the amphiphilic copolymers obtained by derivatization of polymeric chain of poly(N-2-hydroxyethyl)-dl-aspartamide, PHEA, with poly(ethylene glycol)s, PEG (2000 or 5000 Da), and/or hexadecylamine chain, C16, namely PHEA-PEG2000-C16, PHEA-PEG5000-C16, PHEA-C16, have been employed. Preliminary to the kinetic and equilibrium data quantitative treatment, the molar absorption coefficient of TAM in polymeric micelle aqueous solution has been determined. By these studi…

A multiplex polymerase chain reaction protocol for the simultaneous analysis of the glutathione S-transferase GSTM1 and GSTT1 polymorphisms.

1996

Darwinism and pharmacogenomics: from 'one treatment fits all' to 'selection of the richest'?

2004

Pharmacogenomics and pharmacogenetics are relatively new fields, and have arisen from recent advances in genetic research. They offer new perspectives on the development of pharmaceuticals, allowing drug design to be targeted specifically to the genotype of selected populations. The discussion of who will be considered for the development of these tailored drugs and who will be excluded, in a situation in which both research resources and public expenditure are limited, is provoking and has led to several, still unanswered ethical questions and concerns about fairness and the potential discrimination of fringe groups. Based on the statistical analyses of population averages, patient groups …

Contribution of Taq polymerase-induced errors to the estimation of RNA virus diversity.

1998

The genetic diversity of a vesicular stomatitis virus population was analysed by RT-PCR, cloning and sequencing of two approximately 500 nucleotide regions of the virus genome. PCR amplifications were performed in parallel experiments with both Taq and Pfu DNA polymerases, and important differences were observed. Between 10 and 22 mutations were detected when virus populations were analysed by Taq amplification (20 clones from each region), whereas amplification of the same samples with Pfu revealed between 0 and 5 mutations. PCR fidelity assays, performed under the same PCR conditions as those used in the population analysis, showed that the Taq error-rate estimate of 0.27 x 10(-4) misinco…

El populismo penal en Colombia: propuesta para un debate inconcluso

2020

El presente documento argumenta que el populismo penal ha sido interpretado y caracterizado de diversas maneras, pero que, en realidad, no se han planteado propuestas para establecer un “umbral” que permita definir cuándo se trata de una reforma penal legítima y necesaria, y cuándo estamos ante una populista o reaccionaria. Este trabajo propone un modelo aplicado a reformas penales que se podrían considerar populistas, y así, ofrecer un test que permita dar un paso hacia la teoría del populismo penal.

Porphyrin amino acids-amide coupling, redox and photophysical properties of bis(porphyrin) amides.

2013

New trans-AB2C meso-substituted porphyrin amino acid esters with meso-substituents of tunable electron withdrawing power (B = mesityl, 4-C6H4F, 4-C6H4CF3, C6F5) were prepared as free amines 3a-3d, as N-acetylated derivatives Ac-3a-Ac-3d and corresponding zinc(II) complexes Zn-Ac-3a-Zn-Ac-3d. Several amide-linked bis(porphyrins) with a tunable electron density at each porphyrin site were obtained from the amino porphyrin precursors by condensation reactions (4a-4d) and mono- and bis(zinc(II)) complexes Zn(2)-4d and Zn(1)Zn(2)-4d were prepared. The electronic interaction between individual porphyrin units in bis(porphyrins) 4 is probed by electrochemical experiments (CV, EPR), electronic abso…

A recent portrait of bioactive triazoles

2010

Scientists have extensively explored new synthetic routes in order to obtain 1,2,3- and 1,2,4-triazoles as they represent a very interesting class of compounds due to their wide range of biological activities such as antitumor, antiinflammatory, analgesic, antifungal, antibacterial, antiviral, etc. This mini review reports the synthesis and the biological activities of compounds containing a triazole moiety published since 2007. No attempt is made to provide a comprehensive literature overview, our aim is to highlight some more recent examples of synthetic biological active compounds. In particular, we focus on the applications of “click reactions” that allow the regioselective synthesis of…

Electrodeposited nickel–zinc alloy nanostructured electrodes for alkaline electrolyzer

2022

Abstract Over the last decade, as a consequence of the global decarbonization process, the interest towards green hydrogen production has drastically increased. In particular a substantial research effort has focused on the efficient and affordable production of carbon-free hydrogen production processes. In this context, the development of more efficient electrolyzers with low-cost electrode/electrocatalyst materials can play a key role. This work, investigates the fabrication of electrodes of nickel-zinc alloys with nanowires morphology cathode for alkaline electrolyzers. Electrodes are obtained by the simple method of template electrosynthesis that is also inexpensive and easily scalable.…

Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane

2004

The doublet potential energy surfaces involved in the decomposition of the nitromethane radical anion (CH(3)NO(2) (-)) have been studied by using the multistate extension of the multiconfigurational second-order perturbation method (MS-CASPT2) in conjunction with large atomic natural orbital-type basis sets. A very low energy barrier is found for the decomposition reaction: CH(3)NO(2) (-)--[CH(3)NO(2)](-)--CH(3)+NO(2) (-). No evidence has been obtained on the existence of an isomerization channel leading to the initial formation of the methylnitrite anion (CH(3)ONO(-)) which, in a subsequent reaction, would yield nitric oxide (NO). In contrast, it is suggested that NO is formed through the …