Dirac field in topologically massive gravity

We consider a Dirac field coupled minimally to the Mielke–Baekler model of gravity and investigate cosmological solutions in three dimensions. We arrive at a family of solutions which exists even in the limit of vanishing cosmological constant.     

Ionic liquid promoted interrupted Feist-Benary reaction with high diastereoselectivity

A basic ionic liquid, 1-butyl-3-methylimidazolium hydroxide promotes the interrupted Feist-Benary reaction at room temperature under organic solvent-free conditions to produce a variety of substituted hydroxydihydrofurans. The hydroxydihydrofurans are converted to furans (Feist-Benary products) using the ionic liquid, 1-methyl-3-pentylimidazolium bromide at 70-75 °C. The reactions are very clean, high yielding and highly stereoselective.     

Pseudolinear equivalent constant rigidity concept for analyzing welding residual deformation

To ascertain the extent of deformation due to the thermal cycles caused by welding it calls for solving a complex thermal elasto-plastic problem, which is non-linear and involves plastic deformation of the medium at high temperature varying in both time and space. Analytical solutions turned out to be inadequate. At the same time conventional numerical techniques proved to be highly time consuming and thereby prohibitively expensive in real life situations. The concept of pseudolinear equivalent constant rigidity system was developed in this investigation for thermo-mechanical analysis of plates undergoing variation of rigidity due to a continuously changing temperature profile as is encountered in welding situations. The initial non-linear problem with modulus varying with temperature was transformed into a pseudolinear equivalent system of constant rigidity that was solved by applying linear analysis.     

Nonmetricity and torsion induced by dilaton gravity in two dimension

We develop a theory in which there are couplings amongst Dirac spinor, dilaton and non-Riemannian gravity and explore the nature of connection-induced dilaton couplings to gravity and Dirac spinor when the theory is reformulated in terms of the Levi-Civita connection. After presenting some exact solutions without spinors, we investigate the minimal spinor couplings to the model and in conclusion we cannot find any nontrivial dilaton couplings to spinor.     

Visible Light-Enabled sp3-C−H Functionalization with Chloro- and Bromoalkynes: Chemoselective Route to Vinylchlorides or Alkynes

An unprecedented direct atom-economic chemo- and regioselective hydroalkylation of chloroalkynes and an sp³-C−H alkynylation of bromoalkynes was achieved. The reaction partners are unfunctionalized ethers, alcohols, amides, and even non-activated hydrocarbons. We found that a household fluorescent bulb was able to excite a diaryl ketone, which then selectively abstracts a H-atom from an sp³-C−H bond. The product of a formal alkyne insertion into the sp³-C−H bond was obtained with chloroalkynes, providing valuable vinyl chlorides. The photo-organocatalytic hydrogen atom transfer strategy gives rise to a broad range of diversely functionalized olefins. When bromoalkynes are applied in the presence of a base, a chemoselectivity switch to an alkynylation is observed. This reaction can even be performed for the alkynylation of unactivated sp³-C−H bonds, in this case with a preference of the more substituted carbon. Accompanying quantum chemical calculations indicate a vinyl radical intermediate with pronounced linear coordination of the carbon radical center, thus enabling the formation of both diastereoisomers after H-atom abstraction, suggesting that the (Z)-diastereoisomer is preferred, which supports the experimentally observed (E/Z)-distribution.     

Studies on potential utilization of rice husk char in blend with lignite for cocombustion application

Combustion behavior of Indian lignite sample blended with rice husk chars (prepared at low temperature) has been examined in this study through simultaneous differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) technique. Range of inputs obtainable by characteristic TG–DSC parameters has been utilized to arrive at important conclusions and observations in respect of ideal selection of blend proportion, proper utilization of the blend combination, etc. Deviations of experimental mass loss pattern (TG) and of rate curve (DTG) from corresponding expected theoretically calculated pattern have also been noted for different blends to examine possible advantageous or disadvantageous effects. As per the observations recorded, use of biomass char in blends (with lignite) was found to be very much beneficial and its proportion in the blends may be restricted to a level of 40 % by mass to extract maximum benefits in burning performance. This paper also focuses specific advantages of use of rice husk char in place of raw rice husk for cocombustion applications. Moreover, the importance of heat release pattern to assess compatibility of a fuel mix with existing boiler design and also to workout fresh boiler design for cocombustion application has been discussed in this paper.     

Radio-frequency measurements of UNiX compounds (X=Al, Ga, Ge) in high magnetic fields

We performed radio-frequency (RF) skin-depth measurements of antiferromagnetic UNiX compounds (X=Al, Ga, Ge) in magnetic fields up to 60 T and at temperatures between 1.4 to ~60 K. Magnetic fields are applied along different crystallographic directions and RF penetration-depth was measured using a tunnel-diode oscillator (TDO) circuit. The sample is coupled to the inductive element of a TDO resonant tank circuit, and the shift in the resonant frequency Δf of the circuit is measured. The UNiX compounds exhibit field-induced magnetic transitions at low temperatures, and those transitions are accompanied by a drastic change in Δf. The results of our skin-depth measurements were compared with previously published B–T phase diagrams for these three compounds.