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Considerable Rise (considerable + rise)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Reactive grafting of glycidyl methacrylate onto polypropylene

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010
Emma-Louise Burton
Abstract This work explored the melt-phase grafting of glycidyl methacrylate (GMA) onto polypropylene on a closely intermeshing corotating twin-screw extruder (16-mm screws, 40 : 1 length/diameter ratio). The modification of the base polypropylene to produce GMA-grafted polypropylene was achieved via peroxide-induced hydrogen abstraction from the polypropylene followed by the grafting of the GMA monomer or by the grafting of styrene followed by copolymerization with the GMA. In this study, both the position and order of the reactant addition were investigated as a route to improving graft yields and reducing side reactions (degradation). For the peroxide,GMA system, adding GMA to the melt before the peroxide resulted in significant improvements in the graft levels because of the improved dispersion of GMA in the melt. The addition of a comonomer (styrene) was explored as a second route to improving the graft yield. Although the addition of the comonomer led to a considerable rise in the level of grafted GMA, altering the order of the reactant addition was not found to contribute to an increase in the grafted GMA levels. However, variable levels of grafted styrene were achieved, and this may play an important role in the development of grafted polymers to suit specific needs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

GSK3,: role in therapeutic landscape and development of modulators

BRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010
S Phukan
Glycogen synthase kinase-3 beta (GSK3,) is a multifunctional serine/threonine kinase which was originally identified as a regulator of glycogen metabolism. It plays a key role in the regulation of numerous signalling pathways including cellular process such as cell cycle, inflammation and cell proliferation. Over the last few years there is a considerable rise in the number of journals and patents publication by different workers worldwide. Many pharmaceutical companies are focusing on GSK3, as a therapeutic target for the treatment of disease conditions. The present review is focused on signalling pathways of different disease conditions where GSK3, is implicated. In this review, we present a comprehensive map of GSK3, signalling pathways in disease physiologies. Structural analysis of GSK3, along with molecular modelling reports from numerous workers are reviewed in context of design and development of GSK3, inhibitors. Patent landscape of the small molecule modulators is profiled. The chemo space for small molecule modulators extracted from public and proprietary Kinase Chembiobase for GSK3, are discussed. Compounds in different clinical phases of discovery are analysed. The review ends with the overall status of this important therapeutic target and challenges in development of its modulators. [source]

Red-Emitting Rhodamine Dyes for Fluorescence Microscopy and Nanoscopy

CHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2010
Kirill Kolmakov Dr.
Abstract Fluorescent markers emitting in the red are extremely valuable in biological microscopy since they minimize cellular autofluorescence and increase flexibility in multicolor experiments. Novel rhodamine dyes excitable with 630,nm laser light and emitting at around 660,nm have been developed. The new rhodamines are very photostable and have high fluorescence quantum yields of up to 80,%, long excited state lifetimes of 3.4,ns, and comparatively low intersystem-crossing rates. They perform very well both in conventional and in subdiffraction-resolution microscopy such as STED (stimulated emission depletion) and GSDIM (ground-state depletion with individual molecular return), as well as in single-molecule-based experiments such as fluorescence correlation spectroscopy (FCS). Syntheses of lipophilic and hydrophilic derivatives starting from the same chromophore-containing scaffold are described. Introduction of two sulfo groups provides high solubility in water and a considerable rise in fluorescence quantum yield. The attachment of amino or thiol reactive groups allows the dyes to be used as fluorescent markers in biology. Dyes deuterated at certain positions have narrow and symmetrical molecular mass distribution patterns, and are proposed as new tags in MS or LC-MS for identification and quantification of various substance classes (e.g., amines and thiols) in complex mixtures. High-resolution GSDIM images and live-cell STED-FCS experiments on labeled microtubules and lipids prove the versatility of the novel probes for modern fluorescence microscopy and nanoscopy. [source]

Spectroscopic and Electrochemical Evaluation of Salt Effects on Electron-Transfer Equilibria between Donor/Acceptor and Ion-Radical Pairs in Organic Solvents

CHEMPHYSCHEM, Issue 16 2008
Sergiy V. Rosokha Dr.
Abstract Addition of "inert" tetrabutylammonium hexafluorophosphate (Bu4NPF6) to a solution of TMDO/DDQ in dichloromethane (where TMDO=2,2,6,6-tetramethylbenzo[1,2-d;4,5-d]bis[1,3]-dioxole, donor, and DDQ=diclorodicyano-p-benzoquinone, acceptor) is accompanied by drastic changes in the electronic spectrum, which are related to the appearance of the DDQ,. and TMDO+. ion radicals and a decrease in the concentration of the neutral molecules and the charge-transfer complex [TMDO,DDQ]. These changes point to a considerable rise (of about three orders of magnitude) in the apparent electron-transfer equilibrium constant (KET) for this donor/acceptor pair upon increasing the electrolyte concentration from 0 to 0.5,M. Accordingly, the ion-radical fractions and KET values are higher in dichloromethane, at high electrolyte concentrations, than in acetonitrile (where the effect of Bu4NPF6 is less pronounced). Similar trends of the apparent equilibrium constants are observed for the tetramethyl-p-phenylenediamine/tetracyanoethylene pair. Electron-transfer equilibrium constants for both donor/acceptor dyads obtained from spectral measurements are related to those derived from the redox potentials of the reactants. The effects of media variations on the electron-transfer equilibria are discussed within the ion-pairing and ionic-activity frameworks. [source]