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Present Communication (present + communication)
Selected AbstractsVoltammetric Determination of L -Dopa on Poly(3,4-ethylenedioxythiophene)-Single-Walled Carbon Nanotube Composite Modified MicroelectrodesELECTROANALYSIS, Issue 4 2010Jayaraman Mathiyarasu Abstract In the present communication, it is shown that platinum microelectrodes electrochemically coated with a composite of poly(3,4-)ethylenedioxythiophene and single-walled carbon nanotubes (PEDOT/SWNT) enable determinations of 3,4-dihydroxy- L -phenylalaines (L -dopa) in neutral phosphate buffer solutions containing an excess of ascorbic acid. The interpenetrated networked nanostructure of the composite was characterized by scanning electron microscope (SEM) and Raman spectroscopy. It is shown that the presence of the composite gives rise to an increase in the electroactive area of an order of magnitude in compared to the area for the bare microelectrodes. The composite film-coated microelectrode, which yielded reversible cyclic voltammograms for the ferro/ferricyanide redox couple for scan rates between 0.01 and 0.10,V s,1, also gave rise to two well-resolved oxidation peaks for L -dopa and ascorbic acid (AA). The latter effect, which was not seen in the absence of the composite, enabled differential pulse voltammetric determinations of L -dopa in the concentration range between 0.1 to 20,,M with a detection limit of 100,nM. [source] Green Approaches to Field Nitrate Analysis: An Electroanalytical PerspectiveELECTROANALYSIS, Issue 7 2009Radha Desai Abstract The different approaches that have been taken in the development of analytical methods for the determination of nitrate within the field are reviewed. The emphasis has been placed on providing a critical appraisal of the chemistry that underpins current commercial systems and the need to remove the dependence on heavy metal and concentrated acid components. The search for more environmentally acceptable and user friendly systems has long been pursued and the present communication seeks to explore the recent development in portable testing technologies and how they might evolve in the future. In particular, the role of electrochemical techniques in the latter are investigated and their potential application compared and contrasted with the more traditional wet chemical detection strategies. [source] Simplified models for the performance evaluation of desiccant wheel dehumidificationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2003M. Beccali Abstract In the present communication, simple models have been presented to evaluate the performance of rotary desiccant wheels based on different kind of solid desiccants e.g. silica gel and LiCl. The first part of the paper presents ,Model 54' which is developed for silica gel desiccant rotor. The model has been derived from the interpolation of experimental data obtained from the industry and the correlations have been developed for predicting outlet temperature and absolute humidity. The ,Model 54' consists of 54 coefficients corresponding to each correlation for outlet absolute humidity and temperature and it is found that the model predicts very well the performance of silica gel desiccant rotor (Type-I). In the second part of the paper, a psychrometric model has been presented to obtain relatively simple correlations for outlet temperature and absolute humidity. The developed psychometric model is based on the correlations between the relative humidity and enthalpy of supply and regeneration air streams. The model is used to predict the performance of three type of desiccant rotors manufactured by using different kind of solid desiccants (Type I, II and III). The model is tested corresponding to a wide range of measurement data. The developed psychometric model is simple in nature and able to predict very well the performance of different kind of desiccant rotors. Copyright © 2002 John Wiley & Sons, Ltd. [source] Non-biaryl atropisomers. part 1. configurationally stable 1,2-diaryl-3-methyl-1,4,5,6-tetrahydropyrimidinium saltsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2001Maria B. García In the present communication we describe two examples of a new kind of configurationally stable non-biaryl atropisomers in which the Ar-N bond is the chiral axis, namely 1-(o -nitrophenyl)-2-aryl-3-methyl-1,4,5,6-tetrahydropyrimidinium iodides 1. Stereochemical features of such compounds are analyzed on the basis of their 1H and 13C one- and two-dimensional nmr spectra. A comparison is made with the corresponding amidines 2. [source] Contribution of ROCK in contraction of trabecular meshwork: Proposed mechanism for regulating aqueous outflow in monkey and human eyesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2005Emi Nakajima Abstract Aqueous outflow in the conventional outflow pathway is regulated by the contraction and relaxation of the ciliary muscle (CM) and the trabecular meshwork (TM). Rho-associated coiled coil-forming protein kinase (ROCK) is thought to regulate actomyosin-based contractility in many types of cells by phosphorylation of ROCK substrates. In animal models, ROCK inhibitor Y-39983 relaxed CM and TM and decreased intraocular pressure (IOP). Thus, ROCK is implicated in the regulation of aqueous outflow and IOP. However, the site of action of ROCK in monkey and man is unknown. In the present communication, RT-PCR analysis of monkey tissues showed higher levels of mRNAs for ROCK and ROCK substrates in TM compared to CM. Human TM also showed higher levels of mRNAs for ROCK and ROCK substrates compared to CM. Differences between TM and CM in human were not as high as in monkey. ROCK inhibitor Y-39983 led to a dose-dependent relaxation of carbachol-induced, contracted TM from monkey. In contrast, Y-39983 was only slightly effective in relaxing CM. Our results suggested that TM was one of the major sites for regulating IOP by ROCK. ROCK inhibitor Y-39983 might be a candidate drug for lowering IOP by increasing conventional outflow and producing fewer side effects on accommodation and miosis. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:701,708, 2005 [source] A "Click" Strategy for Tuning in situ the Hydrophilic,Hydrophobic Balance of AB MacrosurfactantsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 12-13 2008Zoya Zarafshani Abstract The self-organization of amphiphilic block copolymers in water strongly depends on their molecular structure, in particular on their hydrophilic,hydrophobic balance. Herein, a simple method for tuning the amphiphilicity of polymeric macrosurfactants in aqueous medium is proposed. This concept relies on the "click" ligation of an amphiphilic block copolymer (AB type) and a hydrophilic homopolymer (B type). In the present communication, the validity of this approach was examined with model polymers based on polystyrene (PS) and poly[oligo (ethylene glycol) acrylate] (POEGA) segments. A well-defined , -azido functional diblock copolymer PS- b -POEGA and an , -alkyne functional homopolymer POEGA were prepared using atom transfer radical polymerization. These two polymers could be efficiently coupled to each other via copper-catalyzed azide,alkyne click chemistry in aqueous medium. Moreover, in this coupling strategy, an ester group was introduced at the junction between AB and B segments. This labile moiety may be "cut" by hydrolysis. [source] | ||||||||||