Urinary arsenic species in an arsenic‐affected area of West Bengal,India (part III)

Arsenic contamination of groundwater has long been reported in the Mushidabad district of West Bengal, India. We visited 13 arsenic‐affected families in the Makrampur village of the Beldanga block in Mushidabad during 18–21 December 2001 and collected five shallow tubewell‐water samples used general household purposes, four deep tubewell‐water samples used for drinking and cooking purposes, and 44 urine samples from those families. The arsenic concentrations in the five shallow tubewell‐water samples ranged from 18.0 to 408.4 ppb and those in the four deep tubewell‐water samples were from 5.2 to 9.6 ppb. The average arsenite (arsenic(III)), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate (arsenic(V)) in urine were 28.7 ng mg^?1, 168.6 ng mg^?1, 25.0 ng mg^?1 and 4.6 ng mg^?1 creatinine respectively. The average total arsenic was 227.0 ng mg^?1 creatinine. On comparison of the ratio of (MMA + DMA) to total arsenic, the average proportion was 86.7 ± 9.2% (mean plus/minus to residual standard deviation, n = 43). The exception was data for one boy, whose proportion was 8.0%. One woman excreted the highest total arsenic, at 2890.0 ng mg^?1 creatinine. When using 43 of the urine samples (the exception being the one sample obtained from the boy) there were significantly positive correlations (p < 0.01) between arsenic(III) and MMA, between arsenic(III) and DMA and between MMA and DMA. Copyright © 2005 John Wiley & Sons, Ltd.     

The modelling of radiation heat transfer in forehearths units in glass melting

The interaction between conduction, convection and radiation heat transfer in molten glass has been studied with specific reference to the forehearth units of a glass tank furnace. In shallow molten glass flows as typically encountered in forehearth units, the radiation-conductivity approach for modelling the radiative transfer process is found inappropriate. This is especially so for colourless glasses which are not optically thick below 2.8 microns. In the present work radiative heat transfer process in molten glass has been treated more rigourously by incorporating both optically thick and thin limits. The radiative interaction at the boundaries is treated more realistically. In the case of colourless glasses, the results obtained by the present method show the necessacity to account for the direct radiative interaction between the interior layers of the glass and refractory walls at the top and the bottom. The forehearth exit temperature profiles obtained by using the present method are quite different with those obtained using the radiation conductivity approach.     

Highly Converged Valence Bands and Ultralow Lattice Thermal Conductivity for High‐Performance SnTe Thermoelectrics

A two‐step optimization strategy is used to improve the thermoelectric performance of SnTe via modulating the electronic structure and phonon transport. The electrical transport of self‐compensated SnTe (that is, Sn_1.03Te) was first optimized by Ag doping, which resulted in an optimized carrier concentration. Subsequently, Mn doping in Sn_1.03?xAg_xTe resulted in highly converged valence bands, which improved the Seebeck coefficient. The energy gap between the light and heavy hole bands, i.e. ΔE_v decreases to 0.10 eV in Sn_0.83Ag_0.03Mn_0.17Te compared to the value of 0.35 eV in pristine SnTe. As a result, a high power factor of ca. 24.8 μW cm^?1 K^?2 at 816 K in Sn_0.83Ag_0.03Mn_0.17Te was attained. The lattice thermal conductivity of Sn_0.83Ag_0.03Mn_0.17Te reached to an ultralow value (ca. 0.3 W m^?1 K^?1) at 865 K, owing to the formation of Ag₇Te₄ nanoprecipitates in SnTe matrix. A high thermoelectric figure of merit (z T≈1.45 at 865 K) was obtained in Sn_0.83Ag_0.03Mn_0.17Te.     

Diarylimidoylcyanides,an Attractive Class of Intermediate: Novel Synthesis of α‐Anilino‐β‐Nitroenamines,N, N′‐ Disubstituted Amidines and Substituted Phenyl Glyoxate

The first report of the use of diarylimidoyl cyanides for the synthesis of α‐anilino‐β‐nitrostyrenes, benzamides, and glyoxalic esters is presented, and the advantage of this class of intermediate over diarylimidoyl chlorides is discussed.     

Cyber vulnerability maintenance policies that address the incomplete nature of inspection

In cybersecurity, incomplete inspection, resulting mainly from computers being turned off during the scan, leads to a challenge for scheduling maintenance actions. This article proposes the application of partially observable decision processes to derive cost‐effective cyber maintenance actions that minimize total costs. We consider several types of hosts having vulnerabilities at various levels of severity. The maintenance cost structure in our proposed model consists of the direct costs of maintenance actions in addition to potential incident costs associated with different security states. To assess the benefits of optimal policies obtained from partially observable Markov decision processes, we use real‐world data from a major university. Compared with alternative policies using simulations, the optimal control policies can significantly reduce expected maintenance expenditures per host and relatively quickly mitigate the most important vulnerabilities.     

Tetrametallic Copper Complex to Nanoscale Copper: Selective and Switchable Dehydrogenation-Hydrogenation under Light

A discrete, photoactive, ultrafine copper nanocluster of fewer than hundreds of atoms with stimuli-responsive switchable redox-active states is highly desired to control two different antagonistic reactions. Herein, a mixed-valent tetrametallic copper complex ( C-1 ) of N−O-N Schiff base ligand is disclosed, in which the five different Cu−Cu interactions were used to generate photoactive nanoscale copper [LCu⁰_n, S-1 ] through the reduction of coordinated imine to the amine of C-1 . The presence of a ligand provides stability and helps to homogenize the material ( S-1 ) in the organic solvent. The cluster showed stimuli (O₂/light)-responsive switching between its reduced ( S-1 ) and oxidized [LCu⁰_n−mCuO_m, S-2 ] states that allows it to serve as a highly and poorly active (bistate, relative rate >5–12 fold) catalyst for the dehydrogenation of alcohols to aldehydes and hydrogenation of nitroaromatics to amino aromatics under the light.     

DMSO–POCl3: a reagent for methylthiolation of imidazo[1,2-a]pyridines and other imidazo-fused heterocycles

A practical and metal free method for methylthiolation of imidazo[1,2-a]pyridines and other imidazo-fused heterocycles using DMSO–POCl₃ complex is reported. The reactions are carried out at room temperature that give the corresponding methylthiolated products in good to excellent yield. Further, its application to indole has been demonstrated.     

Any two irreducible Markov chains are finitarily orbit equivalent

Two invertible dynamical systems (X, gA, μ, T) and (Y, ℬ, ν, S), where X, Y are metrizable spaces and T, S are homeomorphisms on X and Y, are said to be finitarily orbit equivalent if there exists an invertible measure preserving mapping ϕ from a subset X ₀ of X of full measure to a subset Y ₀ of Y of full measure such that ϕ|x ₀ is continuous in the relative topology on X ₀, ϕ ⁻¹|Y ₀ is continuous in the relative topology on Y ₀ and ϕ(Orb _T (x)) = Orb _Sϕ (x) for μ-a.e. x ∈ X. In this article a finitary orbit equivalence mapping is shown to exist between any two irreducible Markov chains.