Polymer characterization and gas permeability of poly(1-trimethylsilyl-1-propyne) [PTMSP], poly(1-phenyl-1-propyne) [PPP], and PTMSP/PPP blends

Pure gas and hydrocarbon vapor transport properties of blends of two glassy, polyacetylene-based polymers, poly(1-trimethylsilyl-1-propyne) [PTMSP] and poly(1-phenyl-1-propyne) [PPP], have been determined. Solid-state CP/MAS NMR proton rotating frame relaxation times were determined in the pure polymers and the blends. NMR studies show that PTMSP and PPP form strongly phase-separated blends. The permeabilities of the pure polymers and each blend were determined with hydrogen, nitrogen, oxygen, carbon dioxide, and n-butane. PTMSP exhibits unusual gas and vapor transport properties which result from its extremely high free volume. PTMSP is more permeable to large organic vapors, such as n-butane, than to small, permanent gases, such as hydrogen. PPP exhibits gas permeation characteristics of conventional low free volume glassy polymers; PPP is more permeable to hydrogen than to n-butane. In PTMSP/PPP blends, both n-butane permeability and n-butane/hydrogen selectivity increase as the PTMSP content of the blends increases. © 1996 John Wiley & Sons, Inc.     

Role of dimethyl sulfoxide as a solvent for vinyl polymerization

Dimethyl sulfoxide has been used as a solvent in the polymerization of methyl methacrylate and styrene. The chain-transfer coefficients of the solvent and the values of δ [i.e., (2k_t)^1/2/k_p] in solvent-monomer mixtures of various compositions were determined. δ was observed to be dependent on the solvent concentration in the case of methyl methacrylate but remained constant in case of styrene. The lowering of the values of δ with increasing solvent concentration in case of methyl methacrylate has been attributed to an interaction between the solvent and poly(methyl methacrylate) radical resulting in lower termination rate.     

The gene-protein database of Escherichia coli: edition 5.

The gene-protein database of Escherichia coli is both an index relating a gene to its protein product on two-dimensional gels, and a catalog of information about the function, regulation, and genetics of individual proteins obtained from two-dimensional gel analysis or collated from the literature. Edition 5 has 102 new entries--a 15% increase in the number of annotated two-dimensional gel spots. The large increase in this edition was accomplished in part by the use of a new method for expression analysis of ordered segments of the E. coli genome, which has resulted in linking 50 gel spots to their genes (or open reading frames) and another 45 to specific regions of the chromosome awaiting the availability of DNA sequence information. Communication of information from the scientific community resulted in additional identifications and regulatory information. To increase accessibility of the database it has been placed in the repository at the National Center for Biotechnology Information (NCBI) at the National Library of Medicine under the name ECO2DBASE. It will be updated twice yearly. This edition of the gene-protein database is estimated to contain entries for one-sixth of the protein-encoding genes of E. coli.     

Kinetics and mechanism of substitution of aqua ligands fromcis-diaqua-bis(bipyridyl ruthenium(II)) complex by salicylhydroxamic acid in aqueous medium

The kinetics of substitution of aqua ligands fromcis-[Ru(bipy)₂(H₂O)₂]²⁺ ion by salicylhydroxamic acid (L) in aqueous medium has been studied spectrophotometrically at different temperatures (50–65°C). The following rate law has been established in the pH range 4.0 to 5.8;

Prebiotic Oligosaccharides: Special Focus on Fructooligosaccharides,Its Biosynthesis and Bioactivity

MicroRNAs (miRNAs) are important nonprotein-coding genes involved in almost all biological processes during biotic and abiotic stresses in plants. To investigate the miRNA-mediated plant response to drought stress, two drought-tolerant (C-306 and NI-5439) and two drought-sensitive (HUW-468 and WL-711) wheat genotypes were exposed to 25 % PEG 6000 for 1, 12 and 24 h. Temporal expression patterns of 12 drought-responsive miRNAs and their corresponding nine targets were monitored by quantitative real-time PCR (qRT-PCR). The results showed differential expression of miRNAs and their targets with varying degree of upregulation and downregulation in drought-sensitive genotypes. Likewise, in drought-tolerant wheat genotypes, maximum accumulation of miR393a and miR397a was observed at 1 h of stress. In addition, nearly perfect negative correlation was observed in four miRNA and target pairs (miR164-NAC, miR168a-AGO, miR398-SOD and miR159a-MYB) across all the temporal period studied which could be a major player during drought response in wheat. We, for the first time, validated the presence of miR529a and miR1029 in wheat. These findings gives a clue for temporal and variety-specific differential regulation of miRNAs and their targets in wheat in response to osmotic shock and could help in defining the potential roles of miRNAs in plant adaptation to osmotic stress in future.     

Cu(OAc)2 entrapped on ethylene glycol-modified melamine–formaldehyde polymer as an efficient heterogeneous catalyst for Suzuki–Miyaura coupling reactions

Research on Chemical Intermediates - This work is described as an environmental friendly approach for Cu(OAc)2 entrapped on ethylene glycol-modified melamine–formaldehyde-based polymeric...     

Molecular inversion in the nπ* states: A theoretical investigation of some model systems in a semiempirical molecular orbital framework

The considerations of Walsh rules are extended to rationalize the loss of planarity in the ^1,3nπ* states of simple carbonyl and thiocarbonyl molecules. The role of Fermi correlation in shaping the differences between conformations in the singlet and the triplet state is emphasized. The role played by the π* orbital is also considered.     

LC–MS Simultaneous Determination of Itopride Hydrochloride and Domperidone in Human Plasma

A rapid, simple, sensitive and specific liquid chromatography–tandem mass spectrometry method was developed and validated for simultaneous quantification of itopride hydrochloride and domperidone in human plasma. Both drugs were extracted by liquid–liquid extraction with ethyl acetate and saturated borax solution. The chromatographic separation was performed on a reversed-phase C18 column with a mobile phase of water–methanol (2:98, v/v) containing 0.5% formic acid. The protonated analyte was quantitated in positive ionization by multiple reaction monitoring with a mass spectrometer. The assay exhibited linearity over the concentration range of 3.33–500 ng mL^?1 for itopride hydrochloride and 3.33–100 ng mL^?1 for domperidone in human plasma. The precursor to product ion transitions of m/z 359.1–72.3 and 426.0–147.2 were used to measure itopride hydrochloride and domperidone respectively. The method was found suitable for the analysis of plasma samples collected during phase 1 pharmacokinetics study of itopride HCl 50 mg and domperidone 20 mg in 12 healthy volunteers after single oral doses of the combination drug.