Facet-embedded thin-film III-V edge-emitting lasers integrated with SU-8 waveguides on silicon

A thin-film InGaAs/GaAs edge-emitting single-quantum-well laser has been integrated with a tapered multimode SU-8 waveguide onto an Si substrate. The SU-8 waveguide is passively aligned to the laser using mask-based photolithography, mimicking electrical interconnection in Si complementary metal-oxide semiconductor, and overlaps one facet of the thin-film laser for coupling power from the laser to the waveguide. Injected threshold current densities of 260A/cm(2) are measured with the reduced reflectivity of the embedded laser facet while improving single mode coupling efficiency, which is theoretically simulated to be 77%.     

Identification of Heat-Related ESTs in Moth Bean Through Suppression Subtraction Hybridization

Moth bean (Vigna aconitifolia (Jacq.) Marechal), an important grain-legume crop grown in hot desert regions of Thar, under scorching sun rays, was investigated for heat tolerance at molecular level. In the present study, we constructed a forward suppression subtractive hybridization (SSH) cDNA library of heat tolerant genotype RMO-40 to identify genes expressing under delayed response to elevated temperature. Heat induction was carried out by exposing 14-day-old seedlings to elevated temperature of 42 °C for 30 min. A total of 125 unigenes (33 contigs and 92 singletons) were derived by cluster assembly and sequence alignment of 200 ESTs; out of 125 unigenes, 21 (16 %) were found to be novel to moth bean. Gene ontology functional classification terms were retrieved for 98 (78.4 %) unigenes of which 73 (58.4 %) ESTs were functionally annotated (GO consensus) where 19 unigenes were annotated with 11 enzyme commission (EC) codes and were mapped to 25 different KEGG pathways. We have identified a majority of heat-shock proteins (constituting 35 % of the present library) aiding heat stress tolerance to moth bean. An expression level of 22 ESTs generated from the above SSH cDNA library was studied through semiquantitative RT-PCR assay simultaneously under 5 and 30 min of heat stress at 42 °C.     

Two-field coset space realization of the spin-4 current algebra

A two-field realization of the spin-4 current algebra is obtained through the coset space approach. The transformation properties of these two fields are also deduced through the composition law, which turns out to be a simple generalization of the corresponding diffeomorphic transformation.     

Conformational relaxation dynamics in the excited electronic states of benzil in solution

Relaxation dynamics in the excited singlet (S₁) state of benzil have been studied in solution using pico and subpicosecond transient absorption spectroscopic techniques. The triple exponential decay dynamics of the S₁ state indicates that the process of conformational change from the cis-skewed to the trans-planar form takes place via the formation of a meta-stable intermediate conformer resulting the involvement of two consequent barrier crossing processes. The barrier crossing dynamics is governed by both the polarity of the solvent, which alters the barrier heights by ‘static' interactions, as well as the viscosity of the solvent via ‘dynamical' interactions.     

PHOTOPHYSICAL AND PHOTOCHEMICAL PROPERTIES OF TRITON X-165 IN AQUEOUS AND METHANOLIC SOLUTIONS

Abstract Laser flash photolysis of the nonionic surfactant Triton X-165 was carried out at 248 nm in methanolic and aqueous solutions at different pHs. Cation radical, triplet, phenoxy radical and solvated electron were observed as the transient absorbing species. Various characteristics of these transient species and their decay constants are reported. Photoionization was found to be a major process and it was monophotonic. The results obtained are compared with the photolysis of a small molecule p -methoxytoluene (PMT). Fluorescence and phosphorescence properties of the surfactants Triton X-100, Triton X-165 and PMT are also studied. A suitable reaction scheme is proposed to account for the observed results.     

The Crystal and Molecular Structure of the Dinuclear Mo(VI) Species: [(cis-MoO2L)(μ-O)(cis-MoOL(OH2)]?·?CHCl3 where L?=?(S-benzyl 3-(2-Hydroxyphenyl)Methylenedithiocarbazate)

Abstract  The title dinuclear complex, [(cis-MoO₂L)(μ-O)(cis-MoOL(OH₂)], was characterized as a chloroform solvate. In this structure, one Mo atom features a cis-[MoO₂]²⁺ core to which is also bonded a dinegative, tridentate S-benzyl 3-(2-hydroxyphenyl)methylenedithiocarbazate ligand (= L), via sulfur-, oxygen-, and nitrogen-donors, and a water molecule completes the distorted octahedral coordination geometry. A similar NO₄S donor set is found for the other Mo atom but in this case, the water molecule is substituted by a bridging oxo atom derived from the first Mo species. Two dimers associate via cooperative O–H⋯O hydrogen bonds to form a supramolecular dimer which, in turn, are linked into supramolecular chains via O–H⋯N hydrogen bonding. The complex crystallizes in the triclinic space group P-1 with a = 10.4714(12) ?, b = 10.7627(14) ?, c = 16.708(2) ?, α = 87.916(7)°, β = 76.249(6)°, γ = 83.610(7)°, and Z = 2. Index Abstract  Dinuclear [(cis-MoO₂L)(μ-O)(cis-MoOL(OH₂)], characterized as a chloroform solvate, with octahedral Mo centers, are connected into supramolecular dimers via O–H⋯O hydrogen bonding which are connected via O–H⋯N hydrogen bonds into chains.      

Stability of Circular Orbits in General Relativity: a Phase Space Analysis

Phase space method provides a novel way for deducing qualitative features of nonlinear differential equations without actually solving them. The method is applied here for analyzing stability of circular orbits of test particles in various physically interesting environments. The approach is shown to work in a revealing way in Schwarzschild spacetime. All relevant conclusions about circular orbits in the Schwarzschild-de Sitter spacetime are shown to be remarkably encoded in a single parameter. The analysis in the rotating Kerr black hole readily exposes information as to how stability depends on the ratio of source rotation to particle angular momentum. As a wider application, it is exemplified how the analysis reveals useful information when applied to motion in a refractive medium, for instance, that of optical black holes.     

Triaxial projected shell model study of chiral rotation in odd-odd nuclei

Chiral rotation observed in ¹²⁸Cs is studied using the newly developed microscopic triaxial projected shell model (TPSM) approach. The observed energy levels and the electromagnetic transition probabilities of the nearly degenerate chiral dipole bands in this isotope are well reproduced by the present model. This demonstrates the broad applicability of the TPSM approach, based on a schematic interaction and angular-momentum projection technique, to explain a variety of low- and high-spin phenomena in triaxial rotating nuclei.