Photochemical degradation of blends of polystyrene and poly(2,6 -dimethyl-1,4-phenylene oxide)

Blends of polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide) that cover the entire compositional range have been subjected to the action of singlet oxygen from microwave discharge, dye-sensitized reaction, and photochemical oxidation. With the applied analytical technique, which consisted of infrared (IR) analysis, including ATR technique and a spectroscopic method combined with chemical analysis for hydroperoxide groups, it was not possible to detect any effect of the singlet oxygen treatment. For that reason singlet oxygen does not appear to be important to the initiation of the photooxidation of these blends. In connection with photochemical oxidation the interaction observed between the two components probably involves energy transfer from PS to PPO. This interaction results in the enhancement of reactions in PPO that lead to greater carbonyl group formation and crosslinking. Simultaneously, the probability of chain scission in the PS is lowered with increased PPO content, found by determining the changes in the molecular weights.     

Uranyl coordination environment in hydrophobic ionic liquids: an in situ investigation

Different inner-sphere coordination environments are observed for the uranyl nitrate complexes formed with octyl-phenyl-N,N-diisobutylcarbamoylmethylphosphine oxide and tributyl phosphate in dodecane and in the hydrophobic ionic liquids (ILs) [C(4)mim][PF(6)] and [C(8)mim][N(SO(2)CF(3))(2)]. Qualitative differences in the coordination environment of the extracted uranyl species are implied by changes in peak intensity patterns and locations for uranyl UV-visible spectral bands when the solvent is changed. EXAFS data for uranyl complexes in dodecane solutions is consistent with hexagonal bipyramidal coordination and the existence of UO(2)(NO(3))(2)(CMPO)(2). In contrast, the complexes formed when uranyl is transferred from aqueous nitric acid solutions into the ILs exhibit an average equatorial coordination number of approximately 4.5. Liquid/liquid extraction results for uranyl in both ILs indicate a net stoichiometry of UO(2)(NO(3))(CMPO)(+). The concentration of the IL cation in the aqueous phase increases in proportion to the amount of UO(2)(NO(3))(CMPO)(+) in the IL phase, supporting a predominantly cation exchange mechanism for partitioning in the IL systems.     

Vibrational frequencies and structural determinations of tert-butylacetylene

The normal mode frequencies and corresponding vibrational assignments of tert-butylacetylene (TBA) are examined theoretically using the Gaussian 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of the nine types of motion (C---C stretch, CC stretch, C---H stretch, C---C---C bend, CC---C bend, CC---H bend, H---C---H bend, CH₃ rock, and CH₃ twist) utilizing the C_3v symmetry of the molecule. Calculations were performed at the Hartree–Fock, B3LYP, and MP2 levels of theory using the standard 6-311G^** basis. Theoretical results were successfully compared against available experimental data.     

Rapid enzyme-linked immunoassay for detection of Salmonella in food and feed products: performance testing program

The BIOLINE Salmonella ELISA Test for Salmonella spp., which is a rapid, easy, and convenient assay was evaluated for use in detecting Salmonella in foods and feeds. Each food matrix or feed was artificially contaminated with low levels of Salmonella. Twenty different matrixes were studied and 20 different Salmonella strains from a broad variety of serogroups (B, C, D, E, F, G, H, I, M, O, P, and U) were used. The EUSA Test kit detected levels as low as 1 cfu/25 g sample with at least 4 of the 20 matrixes tested. The test kit is applicable to all sample types tested. The BIOLINE Salmonella ELISA Test kit has been granted AOAC-RI performance tested status.     

An Aldehyde Responsive,Cleavable Linker for Glucose Responsive Insulins

A glucose responsive insulin (GRI) that responds to changes in blood glucose concentrations has remained an elusive goal. Here we describe the development of glucose cleavable linkers based on hydrazone and thiazolidine structures. We developed linkers with low levels of spontaneous hydrolysis but increased level of hydrolysis with rising concentrations of glucose, which demonstrated their glucose responsiveness in vitro. Lipidated hydrazones and thiazolidines were conjugated to the LysB29 side-chain of HI by pH-controlled acylations providing GRIs with glucose responsiveness confirmed in vitro for thiazolidines. Clamp studies showed increased glucose infusion at hyperglycemic conditions for one GRI indicative of a true glucose response. The glucose responsive cleavable linker in these GRIs allow changes in glucose levels to drive the release of active insulin from a circulating depot. We have demonstrated an unprecedented, chemically responsive linker concept for biopharmaceuticals.