A reexamination of the pyrolysis of bis trifluoromethyl peroxide

The literature results for the pyrolysis of bis trifluoromethyl peroxide are reexamined and compared with those for dimethyl peroxide. The thermochemistry yields the result that the π-bond energy in carbonyl fluoride is 96 ± 10 kcal/mol compared to 74 kcal/mol for that in formaldehyde. Thermodynamic additivity contributions are derived for the C? (F)₃(O) and O? (C)(F) groups. Some conclusions are drawn in relation to the oxidation of halogeno methyl radicals and the chemistry of the atmosphere.     

Heats of formation of C1?C4 alkyl nitrites (RONO) and their RO-NO bond dissociation energies

The heats of formation of C₃ and C₄ alkyl nitrites (RONO) have been determined via their heats of combustion by bomb calorimetry, thereby providing a complete set of values of ΔHº_f for C₁-C₄ alkyl nitrites. The experimental values are in excellent agreement with values derived from group additivity rules. For branched compounds these calculations involve corrections for gauche interactions. In these cases, the gauche interactions are reflected in the activation energies E₁ determined by recent kinetic studies, required for breaking the RO-NO bond. The heats of formation of the alkoxy radicals involved together with ΔHº_f(NO) = 21.6 kcal/mole leads to the result D(RO-NO) = 41.5 ± 1 kcal/mole. The concordance between D(thermochemical) and D(kinetic), unlike previous kinetic studies, implies that E₂ = 0 ± 1 kcal/mole.     

End-functionalization of poly(3-hydroxybutyrate)via genetic engineering for solid surface modification

A new approach to end-functionalization of poly(3-hydroxybutyrate)[PHB] is described. Using genetically engineered PHB synthase fused with a 10x-histidine units at its N-terminus, end-functionalized PHB was synthesized and used for the solid surface modification.     

A rigorous stability result for the Vlasov-Poisson system in three dimensions

It is proven that in a neutral two-component plasma with space homogeneous positively charged background, which is governed by the Vlasov-Poisson system and for which Poisson's equation is considered on a cube inR ³ with periodic boundary conditions, the space homogeneous stationary solutions g with energy gradient g/ 0 and compact support are (nonlinearly) stable in the L¹-norm with respect to weak solutions of the initial value problem.     

A simple poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid) transistor for glucose sensing at neutral pH

We demonstrate a simple transistor based on the conducting polymer poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid), capable of sensing glucose in a neutral pH buffer solution by a mechanism involving sensing of hydrogen peroxide.     

Immobilization of pig liver microsomes

Microsomes from pig liver were covalently coupled to Sepharose activated by CNBr and to Sephadex activated by 1,1’-carbonyldiimidazole. Microsomes were also entrapped inside Ca-alginate andk-carrageenan gels. The concentration of immobilized cytochrome P-450 was determined by CO-difference spectra. The activity of the monooxygenase system was demonstrated by theN-demethylation of aminopyrine, theO-demethylation ofp-nitroanisole, and the hydroxylation of perhexiline maleate. Upon immobilization, a 30–40% and a 60–70% decrease in V _max ^app for theOandN-demethylations were respectively observed. The V _max ^app values for the hydroxylation of perhexiline maleate were essentially the same for the different immobilized forms and for the freely suspended microsomal cytochrome P-450. Under storage at 4°C, microsomes entrapped insidek-carrageenan and Ca-alginate were less stable than the free microsomes, whereas immobilization on CNBr-activated Sepharose improved the stability of the hepatic microsomal monooxygenase system at the same temperature. These types of immobilized microsomes have the advantage of being easily recovered and reused for other assays. Finally, microsomes entrapped insidek-carrageenan or Ca-alginate can be used to follow up the continuous metabolization ofp-nitroanisole for several hours in a stirred-batch reactor.     

Formation of modified cytosine residues in the presence of depurinated DNA

[Chemical reaction: See text] Depurination is an important degradation pathway for antisense phosphorothioate oligonucleotides under conditions of thermal stress. We present evidence showing that depurinated oligonucleotides react with cytosine-containing sequences giving products containing a 6-(2-deoxy-beta-D-erythro-pentofuranosyl)-3-(2-oxopropyl)imidazo[1,2-c]pyrimidin-5(6H)-one residue. Further, we demonstrate that the same product is formed upon treatment of 2'-deoxycytidine with 4-oxo-2-pentenal, the latter being an expected byproduct of serial elimination reactions at apurinic sites. In addition to being important for synthetic oligonucleotides, apurinic site formation in cellular DNA is a common occurrence. Because repair of these sites can result in the production of 4-oxo-2-pentenal, it is interesting to speculate whether 6-(2-deoxy-beta-D-erythro-pentofuranosyl)-3-(2-oxopropyl)imidazo[1,2-c]pyrimidin-5(6H)-one residues can form in vivo.     

From second to first order transitions in a disordered quantum magnet

The cross sections and transverse spin asymmetries in the hard exclusive electroproduction of decuplet baryons are calculated in the large N(c) limit and found to be comparable to that of octet baryons. Large N(c) selection rules for the production amplitudes are derived, leading to new sensitive tests of the spin aspects of the QCD chiral dynamics both in the nonstrange and strange sectors. Importance of such studies for the reliable extraction of the pion form factor from pion electroproduction is explained.