The kinetic deuterium isotope effect, D(V/K), on ethanol oxidation was measured by the radiometric, competitive method using 14C-labelled ethanol containing deuterium in the (1-R) position. Acetate was isolated and used for the determination. Experiments were performed on rats either anaesthetized and laparotomized, or provided with indwelling catheters in a. carotis, v. cava and v. portae. Exp...

The oxygen isotope effect of the ferromagnetic transition in itinerant ferromagnet strontium ruthenate SrRuO3 with a Curie temperature Tc of 160 K is studied. We observed for the first time a shift of ∆Tc ~ 1 K by oxygen isotope substitution of 16O → 18O in SrRuO3 by precise measurements of DC and AC magnetizations. The results surprisingly lead to the noteworthy inverse isotope effect with neg...

Weak satellites of the strong and sharp parity-forbidden, but symmetry-allowed 1s(A1)→1s(T2) doublet of the S donor spectrum in silicon are reported. The low-energy ones are ascribed to a Si isotope effect and the high-energy ones to an S isotope effect. We also show that the profile of the low-energy component of the same transition of Se in silicon can be reproduced from the computed combinat...

The remote label method was used to measure primary and secondary (18)O isotope effects in the alkaline hydrolysis of O,O-diethylphosphorylcholine iodide (DEPC) and the primary (18)O effect in the alkaline hydrolysis of O,O-diethyl-m-nitrobenzyl phosphate (DEmNBP). Both the leaving group of interest (choline or m-nitrobenzyl alcohol) and ethanol can be ejected during hydrolysis due to the simil...

We recently reported abnormal secondary deuterium kinetic isotope effects (2° KIEs) for hydride transfer reactions from alcohols to carbocations in acetonitrile (Chem. Comm. 2012, 48, 11337). Experimental 2° KIE values were found to be inflated on the 9-C position in the xanthylium cation but deflated on the β-C position in 2-propanol with respect to the values predicted by the semi-classical t...

The currently available results of the isotope effect on the superconducting transition temperature Tc in Fe-based high-temperature superconductors (HTSs) are highly controversial. The values of the Fe isotope effect exponent �Fe for various families of Fe-based HTS were found to be as well positive, as negative, or even be exceedingly larger than the BCS value �BCS�0.5. Here we emphasize that ...

background : the aim of the current study was to develop a marking technique as an internal marker to mark post blood meal mosquitoes by using stable phosphate isotope 32 p and determine the optimal concentration of it. methods : an isotonic physiological saline solution, containing different concentration of radioactive isotope 32 p-labeled disodium phosphate (na 2 h 32 po4) was injected into ...

The mechanism of L-ribulose 5-phosphate 4-epimerase of Aerobacfer aerogenes has been investigated by determining the kinetic isotope effect (KT/KH) for the epimerization of D-[4-T]xylulose 5-phosphate in the presence of D-[l-14C]xylulose 5-phosphate. The ratio of T:14C was determined for the isolated L-ribulose derived from aliquots of an epimerization reaction mixture during its progress towar...

A 5,5-d2 -luciferin was prepared to measure isotope effects on reactions of two intermediates in firefly bioluminescence: emission by oxyluciferin and elimination of a putative luciferyl adenylate hydroperoxide to dehydroluciferin. A negligible isotope effect on bioluminescence provides further support for the belief that the emitting species is the keto-phenolate of oxyluciferin and rules out ...

The primary, alpha-secondary, beta-secondary, and beta'-secondary deuterium and primary 18O kinetic isotope effects on V/K for the dehydration of [(3S)-3-hydroxybutyryl]pantetheine by bovine liver crotonase (enoyl-CoA hydratase, EC 4.2.1.17) have been determined by the equilibrium perturbation method. The primary deuterium and 18O kinetic isotope effects are 1.61 and 1.051, respectively. The se...