Nature of transient species formed during pulse radiolysis of 4-mercaptopyridine in aqueous solutions: Formation of a dimer radical species by one-electron reduction reaction

Reactions of one-electron reducing as well as oxidizing radicals with 4-mercaptopyridine (4-MPy) were studied in aqueous solutions at different pH values. One-electron oxidizing radicals such as N₃ and Br₂ ^–, react with 4-MPy by electron transfer reaction at pH 11 to give 4-pyridylthiyl radical. The reduction potential for the couple 4-PyS /4-PyS^– was estimated to be 0.93V vs. NHE by equilibrium reaction with I₂ ^– /2I^– couple. At pH 6.8, where the compound is predominantly present in the thione form, the transient species formed is a cation radical. OH radicals react with 4-MPy by addition to the pyridine ring at pH 6.8 and 11. At pH 0, OH radicals as well as one-electron oxidants like Cl₂ ^– and Br₂ ^– radicals react with 4-MPy to produce the protonated form of 4-pyridylthiyl radical. At pH 6.8 and 11, e_aq ^– reaction with 4-MPy gave an initial adducts which reacted with the parent molecule to give dimer radicals. Acetone ketyl radicals were unable to reduce 4-MPy at neutral pH. Reducing radicals like H-atoms and acetone ketyl radicals reacted with 4-MPy at acidic pH by H-abstraction reaction to give the same species as produced by oxidizing radicals.     

Rank procedures for some two-population multivariate extended classification problems

Given independent samples from three multivariate populations with cumulative distribution functions F⁽¹⁾(x), F⁽²⁾(x), and F⁽⁰⁾(x) = θF⁽¹⁾(x) + (1 ? θ)F⁽²⁾(x), where 0 ≤ θ ≤ 1 is unknown, the three-action problem involving decision as to whether the value of θ is high, low, or intermediate, is considered. A class of consistent procedures based on the relative spacing of three sample averages of linearly compounded rank scores is formulated. The asymptotic operating characteristics of the procedures when F⁽¹⁾ and F⁽²⁾ come close together are studied and the best choice of the compounding coefficients in terms of these considered. The consequence of using estimates of the best coefficients on the asymptotic operating characteristics is also examined.     

Determination of persulphate by arsenite using CuII as a catalyst

Summary An indirect volumetric determination of persulphate is based on the reaction with arsenite catalysed by copper(II). An excess of arsenite is added and permanganate is employed for back titration.

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Zusammenfassung Eine indirekte volumetrische Persulfatbestimmung beruht auf der durch Kupfer(II) katalysierten Reaktion mit Arsenit. Es wird überschüssige Arsenitlösung zugegeben und mit Permanganatlösung zurücktitriert.

     

Birkhoff’s rings in the restricted problem of three bodies in a three-dimensional co-ordinate system

In this paper, firstly the trajectory corresponding to the solution of the restricted problem of 3-bodies in a 3-dimensional co-ordinate system has been represented on a 3-dimensional torus and finally, it is seen that the points on the trajectory have one-to-one correspondance with the points on the rings which were studied by Birkhoff [1] for the two-dimensional problem. The special feature of the paper lies in the generalisation of Levi-Civita transformation for a 3-dimensional co-ordinate system to regularise the solutions.     

Heteropoly acid as a novel nitrene transfer agent: a facile and practical aziridination of olefins with Chloramine-T

Environmentally benign HPA is found to be an efficient catalyst for aziridination of olefins in the presence of inexpensive Chloramine-T as a nitrogen source: instantaneous at room temperature, requires only stoichiometric amount of olefin and no allyl amine side product.     

Transport in Porous Media

Table of Contents

Transport in Porous Media     

Analysis of $B^{0}_{d} \to \phi K^{{*0}} $ decay mode with supersymmetry

Motivated by the recent measurement of a low longitudinal polarization fraction in the decay mode , which appears not to be in agreement with the standard model expectation, we analyze this mode in the minimal supersymmetric standard model with the mass insertion approximation. Within the standard model, with the factorization approximation, the longitudinal polarization is expected to be . We find that this anomaly can be explained in the minimal supersymmetric standard model with either the LR or the RL mass insertion approximation. PACS. 13.25.Hw, 11.30.Er, 12.60.Jv Received: 9 May 2005, Revised: 26 July 2005, Published online: 30 August 2005     

Vortex phase qubit: generating arbitrary, counterrotating, coherent superpositions in Bose-Einstein condensates via optical angular momentum beams

We propose a scheme for the generation of arbitrary coherent superpositions of vortex states in Bose-Einstein condensates (BEC) using the orbital-angular-momentum states of light. We devise a scheme to generate coherent superpositions of two such counterrotating states of light using well-known experimental techniques. We show that a specially designed Raman scheme allows for transfer of the optical vortex-superposition state onto an initially nonrotating BEC. This creates an arbitrary and coherent superposition of a vortex and antivortex pair in the BEC. The ideas presented here could be extended to generate entangled vortex states, design memories for the orbital-angular-momentum states of light, and perform other quantum information tasks. Applications to inertial sensing are also discussed.     

A simple and readily integratable approach to toxicity prediction

A simple, highly extensible computational strategy to assess compound toxicity has been developed with the premise that a compound's toxicity can be gauged from the toxicities of structurally similar compounds. Using a reference set of 13645 compounds with reported acute toxicity endpoint dose data (oral, rat-LD(50) data normalized in mg/kg), a generic utility which assigns a compound the average toxicity of structurally similar compounds is shown to correlate well with reported values. In a leave-one-out simulation using the requirement that at least one structurally similar member in a "voting consortium" is present within a reference set, the strategy demonstrates a predictive correlation (q wedge 2) of 0.82 with 57.3% of the compounds being predicted. Similar leave-one-out simulations on a set of 1781 drugs demonstrate a q wedge 2 of 0.74 with 51.8% of the compounds being predicted. Simulations to optimize similarity cutoff definitions, consortium member size, and reference set size illustrate that a significant improvement in the quality and quantity of predictions can be obtained by increasing the reference set size. Similar application of the strategy to subchronic and chronic toxicity data should be possible given reasonably sized reference sets.