Reactions occurring at a carbon atom through the Walden inversion mechanism are one of the most important and useful classes of reactions in chemistry. Here we report an accurate theoretical study of the simplest reaction of that type: the H+CH4 substitution reaction and its isotope analogues. It is found that the reaction threshold versus collision energy is considerably higher than the barrie...

The messenger RNA (mRNA) from 5 of 69 patients with severe hemophilia A did not support amplification of complementary DNA containing the first few exons of the factor VIII (F8) gene but supported amplification of mRNA containing exon 1 of F8 plus exons of the VBP1 gene. This chimeric mRNA signals an inversion breaking intron 1 of the F8 gene. Using an inversion patient, one deleted for F8 exon...

While the reactive pocket of many enzymes has been shown to modify reactions of substrates by changing their chemical properties, examples of reactions whose stereochemical course is completely reversed are exceedingly rare. We report herein a class of water-soluble host assemblies that is capable of catalyzing the substitution reaction at a secondary benzylic carbon center to give products wit...

this study investigated the effectiveness of individual and collaborative outputbasedfocus-on-form instructional tasks on the acquisition of english inversionstructures by efl learners. moreover, it explored the developmental trend oflearners’ inversion acquisition. to this end, 60 homogeneous efl learners wereassigned to individual and collaborative output groups. they were exposed to textsenc...

applying 2d algorithms for inverting the potential field data is more useful and efficient than their 3d counterparts, whenever the geologic situation permits. this is because the computation time is less and modeling the subsurface is easier. in this paper we present a 2d inversion algorithm for interpreting gravity data by employing a set of constraints including minimum distance, smoothness,...

Current inversion condition leads to incorrect operation of current based directional relay in power system with series compensated device. Application of the intelligent system for fault direction classification has been suggested in this paper. A new current directional protection scheme based on intelligent classifier is proposed for the series compensated line. The proposed classifier uses ...

Quantitative NMR spectroscopy (qNMR) is an essential tool in organic chemistry, with applications including reaction monitoring, mechanistic analysis, and purity determination. Establishing the correct acquisition rate for consecutive qNMR scans requires knowledge of longitudinal relaxation time constants (T1) all nuclei being monitored. We report a simple method that about 10-fold faster than ...

A nonperturbative electron transfer rate theory is developed on the basis of reduced density matrix dynamics, which can be evaluated readily for the Debye solvent model without further approximation. Not only does it recover for reaction rates the celebrated Marcus' inversion and Kramers' turnover behaviors, but the present theory also predicts reaction thermodynamics, such as equilibrium Gibbs...

We have studied the mechanism of S(N)2@P reactions in the model systems X(-) + PMe(2)Y and X(-) + POR(2)Y (with R=Me, OH, OMe; and X, Y=Cl, OH, MeO) using density functional theory at OLYP/TZ2P. Our main purpose is to analyze the nature of the Walden inversion in our model nucleophilic substitution reactions. Walden inversion is well-known to proceed, in general, as a concerted umbrella motion ...