Novel Copolymers of Styrene. 10. Halo Ring-Substituted 2-Cyano-3-phenyl-2-propenamides

Novel electrophilic trisubstituted ethylene monomers, halo ring-substituted 2-cyano-3-phenyl-2-propenamides, RPhCH ? C(CN)CONH₂, where R is 2-bromo, 3-bromo, 2-fluoro, 3-fluoro, 2-iodo, 3-iodo, and 4-iodo were prepared and copolymerized with styrene. The monomers were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H- and ¹³C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H- and ¹³C-NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (7-19 wt%), which then decomposed in the 500–800°C range.     

Reveal E. coli 2.0 method for detection of Escherichia coli O157:H7 in raw beef

Reveal E. coli 2.0 is a new lateral-flow immunodiagnostic test for detection of E. coli O157:H7 and O157:NM in raw beef trim and ground beef. Compared with the original Reveal E. coli O157:H7 assay, the new test utilizes a unique antibody combination resulting in improved test specificity. The device architecture and test procedure have also been modified, and a single enrichment protocol was developed which allows the test to be performed at any point during an enrichment period of 12 to 20 h. Results of inclusivity and exclusivity testing showed that the test is specific for E. coli serotypes O157:H7 and O157:NM, with the exception of two strains of O157:H38 and one strain of O157:H43 which produced positive reactions. In internal and independent laboratory trials comparing the Reveal 2.0 method to the U.S. Department of Agriculture-Food Safety and Inspection Service reference culture procedure for detection of E. coli O157:H7 in 65 and 375 g raw beef trim and ground beef samples, there were no statistically significant differences in method performance with the exception of a single internal trial with 375 g ground beef samples in which the Reveal method produced significantly more positive results. There were no unconfirmed positive results by the Reveal assay, for specificity of 100%. Results of ruggedness testing showed that the Reveal test produces accurate results even with substantial deviation in sample volume or device incubation time or temperature. However, addition of the promoter reagent to the test sample prior to introducing the test device is essential to proper test performance.     

微波消解-氢化物发生-原子荧光光谱法测定大米中痕量汞

采用微波消解 氢化物发生 原子荧光光谱法对大米中痕量汞进行了消解、测定。以微波消解为样品前处理方法 ,建立了大米微波消解的最佳分析条件。确定了原子荧光光谱仪的参数设置 ,最佳氢化反应条件以及影响汞测定的相关环境参数。检测限 0 0 0 5ng·mL-1 ,测定大米中汞成分分析标准物质 (GBW 0 85 0 8)中汞的含量 ,其结果与证书值相吻合 ,精密度 2 1 % ,回收率 95 2 %～ 1 0 6 4 %。     

Solid-state NMR studies of bacterial lipoteichoic acid adsorption on different surfaces

Teichoic acids are important to bacteria for surface adhesion, metal ion coordination, and other biological processes crucial to bacterial survival. In particular, the surface adhesion of teichoic acids plays a crucial role in the formation of Gram-positive biofilms. Biofilms have been implicated as the major cause of various chronic infections. Biofilm formation is essentially a four-step process beginning with the adhesion of bacteria to a surface, followed by the excretion of an extracellular polymeric substance (slime), development and maturation of the biofilm architecture, and finally biofilm spreading through bacterial release. Currently, there is very little molecular level information available for the initial adhesion of bacteria to solid surfaces. Solid-state NMR is ideally suited for the study of these samples, thus we use (31)P solid-state NMR experiments to study the initial adhesion of lipoteichoic acid (LTA) to various surfaces. (31)P CP-MAS spectra and T(1)(rho) data demonstrate that the structure of LTA changes when adhered to cellulose, cell wall peptidoglycan (PGN), or TiO(2). However, when LTA is simultaneously adhered to PGN and TiO(2) the observed structure is dependent on the amount of retained water. For LTA on TiO(2), we suggest that the alanine and glucosamine groups interact with the surface. However, during simultaneous adhesion to TiO(2) and PGN, the glucosamine groups bind to the PGN while the alanine groups bind to the surface. This arrangement traps water between the PGN and TiO(2) surface.     

A Journey through Diastereomeric Space: The Design,Synthesis, In Vitro and In Vivo Pharmacological Activity,and Molecular Modeling of Novel Potent Diastereomeric MOR Agonists and Antagonists

Four sets of diastereomeric C9-alkenyl 5-phenylmorphans, varying in the length of the C9-alkenyl chain, were designed to examine the effect of these spatially distinct ligands on opioid receptors. Functional activity was obtained by forskolin-induced cAMP accumulation assays and several compounds were examined in the [³⁵S]GTPgS assay and in an assay for respiratory depression. In each of the four sets, similarities and differences were observed dependent on the length of their C9-alkenyl chain and, most importantly, their stereochemistry. Three MOR antagonists were found to be as or more potent than naltrexone and, unlike naltrexone, none had MOR, KOR, or DOR agonist activity. Several potent MOR full agonists were obtained, and, of particular interest partial agonists were found that exhibited less respiratory depression than that caused by morphine. The effect of stereochemistry and the length of the C9-alkenyl chain was also explored using molecular modeling. The MOR antagonists were found to interact with the inactive (4DKL) MOR crystal structures and agonists were found to interact with the active (6DDF) MOR crystal structures. The comparison of their binding modes at the mouse MOR was used to gain insight into the structural basis for their stereochemically induced pharmacological differences.     

ChemInform Abstract: 3s-Gd2C2Br2, an Isomorph with a New Stacking Sequence

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