1H-4,1,2-Benzothiadiazines from 1,2,3-Benzothiadiazole via Alkylbenzothiadiazolium Salts: A Novel Heterocyclic Ring Expansion Possibly via Nitrogen Ylides.

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Investigations on the Corona performance of a Ceramic disc Insulators integrated with Field Reduction Electrode

This paper presents laboratory investigations on the visible corona and discharge radio noise. Experimental investigations are carried on various types of normal and anti-fog types of ceramic disc insulator at the recently established artificial pollution experimental facility. The results obtained from the experimental investigations show better performance for the disc insulators fitted with field reduction electrodes. In addition to the corona and radio noise investigations the comparisons are also made for the experimental results of the potential distribution across the insulator string (with and without filed reduction electrode) with the simulation results obtained by using Surface Charge Simulation Method.

Can one electrochemically measure the statistical morphology of a rough electrode

We have developed a theory for an electrochemical way of measuring the statistical properties of a nonfractally rough electrode. We obtained the expression for the current transient on a rough electrode which shows three times regions: short and long time limits and the transition region between them. The expressions for these time ranges are exploited to extract morphological information about the surface roughness. In the short and long time regimes, we extract information regarding various morphological features like the roughness factor, average roughness, curvature, correlation length, dimensionality of roughness, and polynomial approximation for the correlation function. The formulas for the surface structure factors (the measure of surface roughness) of rough surfaces in terms of measured reversible and diffusion-limited current transients are also obtained. Finally, we explore the feasibility of making such measurements.

Heterogeneous permanganate oxidations: Synthesis of medium ring keto-lactones via substituent directed oxidative cyclisation

Homoallyl alcohols 4a-b and 5a-b undergo smooth oxidative cyclisation to give the corresponding ring enlarged keto-lactones under heterogeneous permanganate oxidation conditions.

Planar triazinium cations from VO2+-assisted ring cyclizations: a remarkably efficient thiazole species for nuclear staining, PDT and anaerobic photocleavage of DNA

Planar triazinium cationic species, from VO2+-assisted cyclization of 1-(2-thiazolylazo)-2-naphthol, shows efficient DNA intercalative binding, visible light-induced anaerobic plasmid DNA photocleavage activity and photocytotoxicity in HeLa and MCF-7 cancer cells by an apoptotic pathway with selective localization of the compound in the nucleus as evidenced from the nuclear staining and confocal imaging.

Nonlinear effects on rotating disk flow in a cylindrical casing

The flow due to a finite disk rotating in an incompressible viscous fluid has been studied. A modified Newton-gradient finite difference scheme is used to obtain the solution of full Navier-Stokes equations numerically for different disk and cylinder sizes for a wide range of Reynolds numbers. The introduction of the aspect ratio and the disk-shroud gap, significantly alters the flow characteristics in the region under consideration, The frictional torque calculated from the flow data reveals that the contribution due to nonlinear terms is not negligible even at a low Reynolds number. For large Reynolds numbers, the flow structure reveals a strong boundary layer character.

Performance of a pipelined ring algorithm for Fast Fourier Transform on transputer arrays

In this paper a pipelined ring algorithm is presented for efficient computation of one and two dimensional Fast Fourier Transform (FFT) on a message passing multiprocessor. The algorithm has been implemented on a transputer based system and experiments reveal that the algorithm is very efficient. A model for analysing the performance of the algorithm is developed from its computation-communication characteristics. Expressions for execution time, speedup and efficiency are obtained and these expressions are validated with experimental results obtained on a four transputer system. The analytical model is then used to estimate the performance of the algorithm for different number of processors, and for different sizes of the input data.

Stabilized alpha-Ni(OH)2 as electrode material for for alkaline secondary cells

Hydrotalcite-like compounds of formula Ni1-xAl(x)(OH)2(CO3)x/2 . nH2O (x = 0.1 to 0.25), having the same structure as that of alpha-Ni(OH)2, have been synthesized by substituting nickel hydroxide with aluminum. Of these, the compounds of compositions x greater-than-or-equal-to 0.2 are found to have prolonged stability in strong alkaline medium. The electrodes comprising stabilized alpha-Ni(OH)2 of x = 0.2 composition are rechargeable with discharge-capacity values of 240 (+/- 15) mAh-g-1 and are attractive for applications in various alkaline secondary cells employing nickel-positive electrodes.

Reactions of palladium chloride with amino spirocyclic cyclotriphosphazenes: Isolation and Crystal Structures of Novel Mono- and Bimetallic Complexes Formed by the Hydrolysis of a .lambda.5-Diazaphospholane Ring

The reaction of the amino spirocyclic cyclotriphosphazene N3P3(NMe2)4(NHCH2CH2CH2NH) (2) with palladium chloride gives the stable chelate complex [PdCl2.2] (4). An X-ray crystallographic study reveals that one of the nitrogen atoms of the diaminoalkane moiety and an adjacent phosphazene ring nitrogen atom are bonded to the metal. An analogous reaction with the phosphazene N3P3(NMe2)4(NHCH2CH2NH) (1) gives initially a similar complex which undergoes facile hydrolysis to give the novel monometallic and bimetallic complexes [PdCl2.HN3P3(O)(NMe2)4(NHCH2CH2NH2)] (5) and [PdCl{N3P3(NMe2)4(NCH2CH2NH2)}]2(O) (6), which have been structurally characterized; in the former, an (oxophosphazadienyl)ethylenediamine is chelated to the metal whereas, in the latter, an oxobridged bis(cyclotriphosphazene) acts as a hexadentate nitrogen donor ligand in its dianionic form. Crystal data for 4 : a = 14.137(1) angstrom, b = 8.3332(5) angstrom, c = 19.205(2) angstrom, beta = 96.108(7)degrees, P2(1)/c, Z = 4, R = 0.027 with 3090 reflections (F > 5sigma(F)). Crystal data for 5 : a = 8.368(2) angstrom, b = 16.841(4) A, c = 16.092(5) angstrom, beta = 98.31(2)degrees, P2(1)/n, Z = 4, R = 0.049 with 3519 reflections (F > 5sigma(F)). Crystal data for 6 : a = 22.455(6) angstrom, b = 14.882(3) angstrom, c = 13.026(5) angstrom, 6 = 98.55(2)degrees, C2/c, Z = 4, R = 0.038 with 3023 reflections (F > 5sigma(F)).

An electrochemically impregnated sintered-nickel electrode

An electrochemically impregnated sintered-nickel porous electrode with a capacity of 225 +/- 10 mAh per g of active material has been developed. This capacity is comparable with any state-of-the-art nickel hydroxide electrode reported in the literature, such as the stabilized alpha-nickel hydroxides that contain aluminium, iron and other trivalent cations. A technical update on various types of nickel positive electrodes is given.

Pipelined ring algorithm for matrix multiplication on transputer networks: performance analysis and estimation

A parallel matrix multiplication algorithm is presented, and studies of its performance and estimation are discussed. The algorithm is implemented on a network of transputers connected in a ring topology. An efficient scheme for partitioning the input matrices is introduced which enables overlapping computation with communication. This makes the algorithm achieve near-ideal speed-up for reasonably large matrices. Analytical expressions for the execution time of the algorithm have been derived by analysing its computation and communication characteristics. These expressions are validated by comparing the theoretical results of the performance with the experimental values obtained on a four-transputer network for both square and irregular matrices. The analytical model is also used to estimate the performance of the algorithm for a varying number of transputers and varying problem sizes. Although the algorithm is implemented on transputers, the methodology and the partitioning scheme presented in this paper are quite general and can be implemented on other processors which have the capability of overlapping computation with communication. The equations for performance prediction can also be extended to other multiprocessor systems.

Effect of TiO2 electrode thickness on photovoltaic properties of dye sensitized solar cell based on randomly oriented Titania nanotubes

Anatase titania nanotubes (TNTs) have been synthesized from P25 TiO2 powder by alkali hydrothermal method followed by post annealing. The microstructure analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed the formation of anatase nanotubes with a diameter of 9-10 nm. These NTs are used to make photo anode in dye-sensitized solar cells (DSSCs). Layer by layer deposition with curing of each layer at 350 C is employed to realize films of desired thickness. The performance of these cells is studied using photovoltaic measurements. Electrochemical impedance spectroscopy (EIS) is used to quantitatively analyze the effect of thickness on the performance of these cells. These studies revealed that the thickness of TiO2 has a pronounced impact on the cell performance and the optimum thickness lies in the range of 10-14 mu m. In comparison to dye solar cells made of P25, TNTs based cells exhibit an improved open circuit voltage and fill factor (FF) due to an increased electron lifetime, as revealed by EIS analysis. (C) 2011 Elsevier B.V. All rights reserved.

Synthesis of DEF ring skeleton of naulafine alkaloid

6, 8-Dichloro-4, 5-dihydro-2-methyl-[2, 7]acenaphthyridin-1-one (5), obtained from the. reaction of 5-cyano-2, 6-dihydroxy-3, 4-cyclopentenopyridine with Vilsmeier reagent, has been transformed to the key synthon 4a in two steps.

Synthesis of taxanes - The carvone approach; A simple, efficient stereo- and enantio-selective synthesis of the functionalised A ring

A highly stereo- and enantio-selective methodology for the construction of the chiral functionalised A-ring of taxanes, starting from (R)-carvone employing a short, simple and efficient sequence is described.