Long-term ozone trend and its effect on night airglow intensity of Li 6708 ? at Ahmedabad (23°N, 72.5°E), India and Halley Bay (76°S, 27°W), British Antarctic Service Station

A critical analysis has been made of the long-term yearly and seasonal variations of ozone concentration at Ahmedabad (23°N, 72.5°E), India and Halley Bay (76°S, 27°W), a British Antarctic Service Station. The effect of O3 depletion on night airglow emission of Li 6708 ? line at Ahmedabad and Halley Bay has been studied. Calculations based on chemical kinetics show that the airglow intensity of Li 6708 ? line has also been affected due to the depletion of O₃ concentration. The nature of yearly variation and seasonal variation of intensity of Li 6708 ? line for the above two stations have been shown and compared. It has been shown that the rate of decrease of intensity of Li 6708 ? line was comparatively higher at Halley Bay due to dramatic decrease of Antarctic O₃ concentration.     

Short-range order and its effect on the electronic structure of binary alloys: CuZn — a case study

We discuss an application of the generalized augmented space method introduced by one of us combined with the recursion method of Haydock et al (GASR) to the study of electronic structure and optical properties of random binary alloys. As an example, we have taken the 50-50 CuZn alloy, where neutron scattering indicates the existence of short-range order.      

Electric field distribution and simulation of avalanche formation due to the passage of heavy ions in a parallel grid avalanche counter

Electric field distributions and their role in the formation of avalanche due to the passage of heavy ions in parallel grid avalanche type wire chamber detectors are evaluated using a Monte Carlo simulation. The relative merits and demerits of parallel and crossed wire grid configurations are studied. It is found that the crossed grid geometry has marginally higher gain at larger electric fields close to the avalanche region. The spatial uniformity of response in the two wire grid configurations is also compared.      

Effects of three-body atomic interaction and optical lattice on solitons in quasi-one-dimensional Bose-Einstein condensate

We make use of a coordinate-free approach to implement Vakhitov-Kolokolov criterion for stability analysis in order to study the effects of three-body atomic recombination and lattice potential on the matter-wave bright solitons formed in Bose-Einstein condensates. We analytically demonstrate that (i) the critical number of atoms in a stable BEC soliton is just half the number of atoms in a marginally stable Townes-like soliton and (ii) an additive optical lattice potential further reduces this number by a factor of √1 − bg ₃ with g ₃ the coupling constant of the lattice potential and b = 0.7301.      

A Girsanov particle filter in nonlinear engineering dynamics

In this Letter, we propose a novel variant of the particle filter (PF) for state and parameter estimations of nonlinear engineering dynamical systems, modelled through stochastic differential equations (SDEs). The aim is to address a possible loss of accuracy in the estimates due to the discretization errors, which are inevitable during numerical integration of the SDEs. In particular, we adopt an explicit local linearization of the governing nonlinear SDEs and the resulting linearization errors in the estimates are corrected using Girsanov transformation of measures. Indeed, the linearization scheme via transformation of measures provides a weak framework for computing moments and this fits in well with any stochastic filtering strategy wherein estimates are themselves statistical moments. We presently implement the strategy using a bootstrap PF and numerically illustrate its performance for state and parameter estimations of the Duffing oscillator with linear and nonlinear measurement equations.     

Surface and interfacial structural characterization of MBE grown Si/Ge multilayers

Si/Ge multilayer structures have been grown by solid source molecular beam epitaxy (MBE) on Si (1 1 1) and (1 0 0) substrates and were characterized by high-resolution X-ray diffraction (XRD), atomic force microscopy (AFM), high-depth-resolution secondary ion mass spectroscopy (SIMS) and cross-section high-resolution transmission electron microscopy (HRTEM). A reasonably good agreement has been obtained for layer thickness, interfacial structure and diffusion between SIMS and HRTEM measurements. Epitaxial growth and crystalline nature of the individual layer have been probed using cross-sectional HRTEM and XRD measurements. Surface and interface morphological studies by AFM and HRTEM show island-like growth of both Si and Ge nanostructures.     

Ideal Gas with a Varying (Negative Absolute) Temperature: an Alternative to Dark Energy?

The present work is an attempt to investigate whether the evolutionary history of the Universe from the offset of inflation can be described by assuming the cosmic fluid to be an ideal gas with a specific gas constant but a varying negative absolute temperature (NAT). The motivation of this work is to search for an alternative to the “exotic” and “supernatural” dark energy (DE). In fact, the NAT works as an “effective quintessence” and there is need to deal neither with exotic matter like DE nor with modified gravity theories. For the sake of completeness, we release some clarifications on NATs in Section 3 of the paper.     

Exclusive measurement of the nonmesonic weak decay of the lambda(5)He hypernucleus

We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay of lambda(5)He formed via the 6Li(pi+, K+) reaction. The energies of the two nucleons and the pair number distributions in the opening angle between them were measured. In both np and nn pairs, we observed a clean back-to-back correlation coming from the two-body weak reactions of lambda p --> np and lambda n --> nn, respectively. The ratio of the nucleon pair numbers was N(nn)/N(np) = 0.45 +/- 0.11(stat) +/- 0.03(syst) in the kinematic region of cos theta(NN) < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of gamma(lambda p --> np)/gamma(lambda n --> nn). The ratio is consistent with recent theoretical calculations based on the heavy meson and/or direct-quark exchange picture.     

Stability indicating liquid chromatographic method for simultaneous quantification of betamethasone valerate and tazarotene in in vitro and ex vivo studies of complex nanoformulation

Low‐potency corticosteroid betamethasone valerate and vitamin‐A tazarotene are used in combination for effective treatment of psoriasis. There is no robust high‐performance liquid chromatography analytical technique available for simultaneous estimation of betamethasone valerate and tazarotene in conventional and nanocarriers based formulations. A simple, accurate, robust isocratic high‐performance liquid chromatography method was developed for simultaneous estimation of betamethasone valerate and tazarotene in topical pharmaceutical formulations. The developed method was validated as per the regulatory guidelines. The validated method was linear over the concentration range of 150–6000 ng/mL (r² > 0.999) at 239 nm wavelength. Limits of detection and quantification of two analytes were 50 and 150 ng/mL, respectively. The %relative standard deviation for intraday and interday precision was less than 2%. The method was also evaluated in the presence of forced degradation conditions. The developed method was successfully applied for in vitro and ex vivo drug release studies of in‐house designed nanoformulations.     

Pharmacophore mapping of flavone derivatives for aromatase inhibition

Aromatase, which catalyses the final step in the steroidogenesis pathway of estrogen, has been target for the design of inhibitor in the treatment of hormone dependent breast cancer for postmenopausal women. The extensive SAR studies performed in the last 30 years to search for potent, selective and less toxic compounds, have led to the development of second and third generation of non-steroidal aromatase inhibitors (AI). Besides the development of synthetic compounds, several naturally occurring and synthetic flavonoids, which are ubiquitous natural phenolic compounds and mediate the host of biological activities, are found to demonstrate inhibitory effects on aromatase. The present study explores the pharmacophores, i.e., the structural requirements of flavones (Fig. 1) for inhibition of aromatase activity, using quantitative structure activity relationship (QSAR) and space modeling approaches. The classical QSAR studies generate the model (R (2) = 0.924, Q (2) = 0.895, s = 0.233) that shows the importance of aromatic rings A and C, along with substitutional requirements in meta and para positions of ring C for the activity. 3D QSAR of Comparative Molecular Field Analysis (CoMFA, R (2) = 0.996, [Formula: see text]) and Comparative Molecular Similarity Analysis (CoMSIA, R (2) = 0.992, [Formula: see text]) studies show contour maps of steric and hydrophobic properties and contribution of acceptor and donor of the molecule, suggesting the presence of steric hindrance due to ring C and R'-substituent, bulky hydrophobic substitution in ring A, along with acceptors at positions 11, and alpha and gamma of imidazole ring, and donor in ring C favor the inhibitory activity. Further space modeling (CATALYST) study (R = 0.941, Delta( cost ) = 96.96, rmsd = 0.876) adjudge the presence of hydrogen bond acceptor (keto functional group), hydrophobic (ring A) and aromatic rings (steric hindrance) along with critical distance among features are important for the inhibitory activity.