An analysis of lasing without inversion in a three level system in terms of vector representation

In the present work, we show that the problem of Λ-type three level systems and lasing without inversion can be understood in terms of evolution of vectors. The time evolutions of these vectors have been worked out using the transition probabilities and detuning. One of the salient features of the work is that Glauber-Sudershan’s p-function can be visualized with this approach. We also present a comparative study between different vector models representing three level Λ-type lasers.     

Thermal decomposition kinetics,flammability, and mechanical property study of wood polymer nanocomposite

Melamine formaldehyde-furfuryl alcohol copolymer was impregnated into softwood in combination with 1,3-dimethylol-4,5-dihydroxy ethyleneurea, a crosslinking agent, nanoclay, and a renewable polymer, collected as gum from a local plant (Moringa oleifera) under vacuum condition and polymerized by catalyst heat treatment. Fourier-transform infrared spectroscopy, X-ray diffractometry, and scanning electron microscopy were used to characterize the nanocomposites. Transmission electron microscopy showed uniform distribution of nanoclay in the composites. The mechanical properties were improved after the addition of plant polymer. The plant polymer had a marked influence on the flammability and thermal stability of the prepared composites. The apparent activation energy was determined by Ozawa-Flynn-Wall’s and Vyazovkin methods. The activation energy of the composites decreased up to a certain decomposed fraction thereafter it remained constant. Higher the plant polymer content higher was the activation energy of the prepared composites which indicated a better interfacial adhesion and thermal stability.     

Enantioselective permeation of racemic alcohol through polymeric membrane

Copolymer of 1,2-bis(2-methyl-1-triethylsiloxy-1-propenyloxy)ethane and dialdehyde have been synthesized by Mukaiyama Aldol polymerization using lipase as the catalyst. The chirality of the polymer was tested by optical rotation and circular dichroism study. The membrane forming ability of this chiral polymer was examined by casting the membrane in three different solvents viz., N-methyl-2-pyrilidone (NMP), dimethyl formamide (DMF) and dimethyl acetamide (DMAc) using the phase inversion method and it was found that chiral polymer–NMP membranes formed more uniform and regular surface morphology as was evident from SEM analysis. The enantioselective membranes prepared in the solvents was tested for resolution of racemic alcohol and it was found that NMP is the best solvent for obtaining highest enantioselectivity value. It was also found that the enantioselectivity for adsorption favoured the (S)-isomer whereas permeation favoured the (R)-isomer which is confirmed from interpretation of the adsorption isotherm by Langmuir model. Accordingly, the enantioselective permeation was caused by suppression of the (S)-isomer permeation. Optical resolution of (±)trans-sobrerol was achieved by pressure driven permeation through the membrane. The highest enantioselectivity, enantiomeric excess and permeation co-efficient was obtained as 98.59%, 20.42 and 13.627 m² h⁻¹, respectively. With an increase in polymer content in the membrane, the permeation rate increases.     

Bounds on the Slope and Curvature of Isgur-Wise Function in a QCD-Inspired Quark Model

The quantum chromodynamics-inspired potential model pursued by us earlier has been recently modified to incorporate an additional factor ‘c’ in the linear cum Coulomb potential. While it felicitates the inclusion of standard confinement parameter b?=?0.183 GeV² unlike in previous work, it still falls short of explaining the Isgur-Wise function for the B mesons without ad hoc adjustment of the strong coupling constant. In this work, we determine the factor ‘c’ from the experimental values of decay constants and masses and show that the reality constraint on ‘c’ yields bounds on the strong coupling constant as well as on slope and curvature of Isgur-Wise function allowing more flexibility to the model.     

Benedict's solution/ vitamin C: An alternative catalytic protocol for the synthesis of regioselective‐1,4‐disubstituted‐1H‐1,2,3‐triazoles at room temperature

A novel and highly efficient method for the synthesis of 1,4‐disubstituted‐1H‐1,2,3‐triazoles by copper‐catalyzed azide‐alkyne cycloaddition has been developed. This economic and sustainable protocol uses a readily available Benedict's solution/Vitamin C catalyst system affording a wide range of 1,4‐disubstituted‐1H‐1,2,3‐triazoles under mild conditions.     

An Improved Analysis of Masses and Decay Constants of Heavy Flavour Mesons within Variational Approach

We employ the variational method to study the properties such as masses, decay constants, oscillation frequency and branching ratios of leptonic decays of heavy flavour mesons with linear cum coulomb Cornell potential.Gaussian function, Coulomb wave function and Airy function are taken as the trial wave-function of variational method in this study. Our analysis suggests that Gaussian trial wave-function provides results which are in close proximity with the experimental results. We also make a comparison with the results from QCD Sum rules and lattice QCD, as well as with recent PDG data.     

Integrated approach to computational and experimental flow visualization of a double annular confined jet

The cold flow of a prototype industrial burner in a cylindrical combustion chamber is investigated. Two concentric annular axial jets simulate this complex flow field, which is investigated using Laser Sheet flow Visualization (LSV), Digital Particle Image Velocimetry (DPIV), Laser Doppler Velocimetry (LDV) and Computational Fluid Dynamics (CFD). The aim is to advance the physical understanding of combustion chamber flow fields and to assist the development of CFD codes specialized in such flows. These simulations generate large amount of data for various measured and calculated quantities. Thus, visualization and comparison procedures are applied for the validation of obtained results. The study reported here is one of the experiments applied in the design of the Quantitative Flow Field Visualization (QFView) software, a web-based environment which supports distributed data access. The application of QFView data analysis greatly improved the understandings about the various transition regions of the flow under investigation.     

Substituted imidazole complexes of platinum(IV) halides

Platinum(IV) halides formed complexes of the type PtL₂X₄ [L=1-vinyl imidazole (1,-VIm), 1-methylimidazole (1-MeIm), 1,2-dimethylimidazole (1,2-Me₂Im), 1-vinyl-2-methylimidazole (1-V-2-MeIm), 2-methylimidazole (2-MeIm), 2-ethylimidazole (2-EtIm), 2-isopropylimidazole (2-i-PrIm), and 4-methylimidazole (4-MeIm); X=Cl, Br] in neutral aqueous solution. The 1-n-butylimidazole (1-n-BuIm) ligand yielded only (LH)₂PtX₆ compound in the same medium. The compounds were characterised by elemental analyses, IR, UV-VIS and ¹HNMR spectra.