Superconducting state parameters of ternary metallic glasses

The well-known empty core (EMC) model potential of Ashcroft was used to study the theoretical investigation of the superconducting state parameters (SSP) viz. electron-phonon coupling strength λ, Coulomb pseudopotential µ*, transition temperature T _C, isotope effect exponent α and effective interaction strength N _O V of some ternary metallic glasses. Most recent local field correction function due to Sarkar et al is used to study the screening influence on the aforesaid properties. Quadratic T _C equations have been proposed and found successful. Also, the present findings are found to be in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the ternary superconductors. The pseudo-alloy-atom (PAA) model was applied for the first time instead of Vegard’s law.     

Creating multipoint-to-point LSPs for traffic engineering

Traffic engineering enhances an ISP's capability to manage and utilize its resources effectively. MPLS has emerged as an efficient packet forwarding tool that gives a significant boost to the traffic engineering capabilities of an ISP. A fundamental problem in MPLS is to reduce label space usage by label switched paths while meeting the requirements of the flows traversing the network. Using multipoint-to-point LSP trees has been proposed as one of the techniques to reduce label space usage. We look at the problem of creating multipoint-to-point LSPs given a set of precomputed point-to-point LSPs. We propose a heuristic for multipoint-to-point LSP creation and show its effectiveness.     

Ferroelectric hysteresis in simultaneously stretched andcorona-poled PVDF films

SSCP (simultaneous stretching and corona poling) of PVDF (polyvinylidene fluoride) films has enhanced the ferroelectric properties. D-E hysteresis loops of these films were observed by using the Sawyer-Tower method in the field range 35 to 80 MV/m. The dependence of ferroelectric hysteresis on poling field has also been studied. The average value of remanent polarization ≈82 mC/m² was observed for the SSCP (simultaneous stretching and corona poling) films, which is significantly higher than the value P≈62 mC/m² observed for the STCP (stretched and then corona poled) films. Coercive fields of E_c≈61 and 50 MV/m were obtained for the SSCP and the STCP films respectively. A comparison of the IR spectra of the SSCP and the STCP films in perpendicularly polarized light E_⊥ indicates that the dipolar orientation is better in the SSCP films     

Inhibitory effect of folinic acid on radiation-induced micronuclei and chromosomal aberrations in V79 cells

Folinic acid (FA), clinically called leucovorin, has been widely used as a nutrient supplement in dietary intake and is capable of inhibiting cytotoxicity and chromosomal damage induced by chemicals. However, data on its antigenotoxic effect on radiation-induced chromosomal damage are limited. The present study was, therefore, performed to investigate the effect of FA on radiation-induced (X-rays and UV radiation) micronuclei (MN) and structural chromosomal aberrations (SCA) concurrently in V79 Chinese hamster lung cells. Exponentially growing cells were exposed to five doses of X-rays (1-12 Gy) and UV radiation (50-800 microJ x 10(2)/cm2) and post-treated with 5 or 50 micrograms FA/ml of culture medium for 16 h. The slides were analyzed for the presence of MN and SCA using standard procedures. The results showed that X-ray treatment alone produced dose-related cytotoxicity as measured by nuclear division index (NDI) and mitotic index (MI). X-rays produced a clear dose-related clastogenicity as measured by percent of micronucleated binucleated cells (MNBN) (5-79%) and percent of aberrant cells (11-92%). FA at 5 micrograms/ml slightly decreased X-ray induced chromosomal damage in both assays; however, the inhibition was significant (12-46% of MNBN, 14-48% in aberrant cells) only when X-ray-treated cultures were post-treated with 50 micrograms FA/ml. Post-treatment of FA had no effect on X-ray induced cytotoxicity as measured by NDI and MI. A similar a dose-related increase in % MNBN (0.5-10.3%) and percent aberrant cells (6-35%) was produced by UV radiation treatment alone. There were significant percentages of MNBN and aberrant cell inhibitions at both 5 and 50 micrograms/ml in both assays. As in the case of X-ray-treated cells, there was a clear dose-related cytotoxicity in UV-treated cells alone. No reduction in NDI or MI was found when UV-exposed cells were post-treated with 5 or 50 micrograms of FA. These data demonstrate the beneficial effect of FA in decreasing radiation-induced chromosomal damage.     

Comments on the criticism of Sarvajit Singh on the paper ‘Surface waves in fibre-reinforced anisotropic elastic media’

Though the decoupling of displacement potentials in case of fibrereinfoced anisotropic elastic media is not possible in the general case, an attempt has been made to decouple the equation as a particular case. The assumptions made in this paper satisfy both set of equations formed by the displacement potentials, which is the main feature of the criticism made by Sarvajit Singh     

System-level modeling and simulation of biochemical assays in lab-on-a-chip devices

We present a “mixed-methodology” based system-level modeling and simulation for biochemical assays in lab-on-a-chip (LoC) devices. The methodology uses a combination of numerical schemes and analytical approaches to simulate biological and physicochemical processes, specifically, an integral approach for fluid flow and electric field, method of lines (MOL) and two-compartment models for biochemical reactions, and Fourier series-based model for analyte mixing. The solution procedure begins with decomposing the LoC device into a system of inter-connected components (e.g., channels and junctions) and the models are solved in a network fashion. Models are developed to accurately capture the multi-physics (e.g., flow, mixing, and reaction) behavior of individual components. The assembly of the components is facilitated via exchange of fluid flux and Fourier series coefficients (or average concentration) of analytes between various components, which enables network solution of the models. The system models are validated against both experimental and numerical models on various biochemical assays (e.g. immunoassays and enzymatic reactions), showing significant computational speedup (100–10,000-fold depending on the assay) without appreciably compromising accuracy (<10% error relative to numerical analysis).     

An Approach for Extracting Small-Signal Equivalent Circuit of Double Heterojunction δ-Doped PHEMTs for Millimeter Wave Applications

Pseudomorphic high electron mobility transistors (PHEMTs) are very important in millimeterwave application. A simple and accurate method for extracting small-signal equivalent curcuit for Double Heterojunction δ-doped PHEMT valid up to 40GHz is presented. First, the parasitic parameters of the equivalent circuit are determined using pinch off PHEMT except for PAD capacitances. The initial intrinsic elements are then determined by conventional analytical method. Advanced Design System is then used to optimize the whole model parameters with very small dispersion of initial values. Good agreement is obtained between simulation results and measured results for a 0.25um DH PHEMT.     

Adaptive and hierarchical modelling of fatigue crack propagation

A methodology is developed to simulate adaptively and hierarchically fatigue crack growth in structural components. Cracks are modelled, by overlaying portions of the finite element mesh free of cracks with a discontinuous finite element field containing unconstrained double nodes along the discontinuity. Crack propagation is simulated by advancing the crack front in the superimposed mesh only keeping the underlying mesh fixed. Adaptivity in time and space domain together with the hierarchical nature of the method ensure both economical and reliable simulation of crack propagation. Numerical results of fatigue crack growth in the attachment lug were found to be, in good agreement with the experimental data.