Monoamine oxidase and succinate dehydrogenase inhibitory properties of substituted 1,3,4-oxadiazole-2-thiones

Fifteen new 3-arylaminomethyl-5-(2-hydroxy-3,5-dibromophenyl)-1,3,4-oxadiazole-2-thiones were synthesized and characterized by their sharp melting points, elemental analyses and ir spectra. These substituted oxadiazolylthiones were evaluated for their enzyme inhibitory activity. All compounds inhibited in vitro monoamine oxidase and succinate dehydrogenase activity of rat brain homogenates. The degree of monoamine oxidase inhibition ranged from 59-93% at a final concentration of 1 × 10^?4 M whereas the inhibition of succinate dehydrogenase was 49-100% at a final concentration of 5 × 10^?5 M.     

Field-cooled measurements of harmonic generation in magnetization of high-T c superconductors

We present measurements of harmonic generation in the magnetization of sintered pellets of YBa₂Cu₃O₇ and Bi_1.7Pb_0.3Sr₂Ca₂Cu₃O₁₀ as a function of DC field. The DC field is applied in the field-cooled mode. Measurements are made at 77 K for various values of the AC field amplitude. A comparison is made with calculations done within the critical state model.     

Properties of quark matter governed by quantum chromodynamics (II). Renormalization schemes in quark matter

Renormalization schemes are examined (in the Coulomb gauge) for quantum chromodynamics in the presence of quark matter. We demand that the effective coupling constant for all schemes become congruent with the vacuum QCD running coupling constant as the matter chemical potential, μ, goes to zero. Also, to enable us to standardize with the vacuum QCD running coupling constant at some asymptotic momentum transfer, $\text{|}\text{p}{}_0\text{|,}\text{we keep}\text{μ ? ¦}\text{p}{}_0\text{¦}$, to ensure that the matter contribution is negligible at this point. This means all schemes merge with vacuum QCD at $\text{|}\text{p}{}_0\text{|}$ and beyond. Two renormalization group invariants are shown to emerge: (i) the effective or invariant charge, g_inv², which is, however, scheme dependent and (ii) g²(M)/S(M), where S(M)^?1 is the Coulomb propagator, which is scheme independent. The only scheme in which g_inv² is scheme independent and identical to g²(M)/S(M) is the screened charged scheme (previous paper) characterised by the normalization of the entire Green function, S^?1, to unity. We conclude that this is the scheme to be used if one wants to identify with the experimental effective coupling in perturbation theory. However, if we do not restrict to perturbation theory all schemes should be allowed. Although we discuss matter QCD in the Coulomb gauge, the above considerations are quite general to gauge theories in the presence of matter.     

Fractals in one and two dimensions of medium energy particles in 800 GeV p-AgBr interactions

We present the first experimental results on self-similar nature of fluctuations of one and two-dimensional density distributions of medium energy particles in 800 GeV p-AgBr interactions. The density fluctuations as measured by 1?D _q are found to be more in two dimensions as compared to those in one dimension, whereas the fluctuations decrease with increase in multiplicity. It has been found that the self-similar cascade model with multifractal properties describes well the observed fluctuations. The ratios of multifractal power law indices are found to be independent of the dimensionality of phase space and of multiplicity.     

Thermal studies on oligosilylbiguanides: A mechanistic approach

Thermal decomposition of oligo-1,4-bis(silyl)-5-propyl/phenylbiguanides, 1–4 under controlled conditions (130–140 °C/N₂) proceeds predominantly via the formation of organic amines, cyclic silazanes and cyclic silylcarbodiimides. Detection of these low molecular weight products accounts for the low residual yields in thermogravimetric analysis of 1–4. A plausible mechanism for thermal degradation is suggested.     

Some thermodynamic parameters for hydroxy amino acids: Bicine and tricine

pK values of N,N-dihydroxyethylglycine (bicine) and N-[tris(hydroxymethyl)methyl]-glycine (tricine) have been determined by the Irving-Rossotti method in an aqueous medium at 25, 30, 35, 40, 45, and 50°C and at different ionic strengths (I = 0.1, 0.5, and 1.0). Plots between pK_a(NH) and 1/T for various ionic strengths have been obtained and the values of slopes have been used to calculate the ΔH, ΔS, and ΔG for the dissociation reactions of bicine and tricine. The ΔH, ΔS, and ΔG values for bicine were found to be 10.6 ± 0.6 kcal mol^?1, ?1.9 ± 1.8 e.u., and 11.1 ± 0.06 kcal mol^?1, respectively, and for tricine 11.2 ± 0.6 kcal mol^?1, 1.6 ± 1.6 e.u., and 10.7 ± 0.06 kcal mol^?1, respectively. The pK_a(NH) values decrease with rise in temperature but the influence of ionic strength is not significant.     

Kinetics and mechanism of oxidation of hydroxylamine by tetrachloroaurate(III) ion

The oxidation of H₂NOH is first-order both in [NH₃OH⁺] and [AuCl₄ ^–]. The rate is increased by the increase in [Cl^–] and decreased with increase in [H⁺]. The stoichiometry ratio, [NH₃OH⁺]/[AuCl₄ ^–], is 1. The mechanism consists of the following reactions.