Modeling of two-phase flows with surface tension by finite pointset method (FPM)

A meshfree method for two-phase immiscible incompressible flows including surface tension is presented. The continuum surface force (CSF) model is used to include the surface tension force. The incompressible Navier–Stokes equation is considered as the mathematical model. Application of implicit projection method results in linear second-order partial differential equations for velocities and pressure. These equations are then solved by the finite pointset method (FPM), which is a meshfree and Lagrangian method. The fluid is represented as finite number of particles and the immiscible fluids are distinguished by the color of each particle. The interface is tracked automatically by advecting the color functions for each particle. Two test cases, Laplace's law and the Rayleigh–Taylor instability in 2D have been presented. The results are found to be consistent with the theoretical results.     

Secondary X-Ray Environment in the Lower Atmosphere of the Earth during Monsoon Season over Udaipur City （India） in July-September 2006

We present a study on the secondary x-rays of energy band 2-100 keV emitted by the intruded principal pollutant components （gases and minerals） brought up in the lower atmosphere by dust storms, monsoon drift and the gravitational pull on meteoritic showers. On the ground we employed a 1.5 × 1 inch^2 NaI crystal in a scintillation detector, suitable for the energy range 2-100 keV of secondary x-rays, providing better energy resolution than a larger sized crystal. In order to eliminate the radioactive background of the Earth, the detector was well shielded on all sides with the help of the lead （Pb） container, except with a.small open window at the top to permit only vertically incident secondary radiation. The results from the data analysis obtained during the monsoon over Udaipur city （India） during the period from July to September （2006） have revealed a linear correlation between dust storm cure monsoon clouds and observed luminosities of secondary x-ray radiation from intruded pollutants. We found intense flux of secondary x-rays from the intruded pollutants when heavy dust and monsoon clouds were brought up by dust storms and monsoon drift in the lower atmosphere over Udaipur city as compared to normal days. Thus, secondary x-rays in the environment provide a tool for investigation of local intrusive pollutant components in the lower atmosphere.     

Locally Rotationally Symmetric Bianchi Type-Ⅰ Model with Time Varying Λ Term

We investigate the locally rotationally symmetric （LRS） Bianchi type-Ⅰ cosmological model for stiff matter and a vacuum solution with a cosmological term proportional to R^-m （R is the scale factor and m is a positive constant）. The cosmological term decreases with time. We obtain that for both the cases the present universe is accelerating with a large fraction of cosmological density in the form of a cosmological term.     

Free Radical Synthetic Protocol for Benzothiazoles via Ring Opening of Benzotriazole: A Two‐step Organic Chemistry Experiment for Undergraduate and Postgraduate Students

The utility and advantages of benzotriazole methodology have been described for the practical synthesis of benzothiazoles. The two‐step synthetic procedure includes nucleophilic acyl substitution followed by benzotriazole ring cleavage under the free radical condition and subsequent cyclization via elimination of molecular nitrogen (N₂). This protocol requires cheap and readily available reagents, and moreover easy to handle, thus can be used to teach undergraduate and postgraduate students about the importance of benzotriazole moiety in organic synthesis, ring cleavage chemistry, cyclization reactions, and use of industrial waste in free radical reactions. Students can also learn some important and common techniques useful in organic chemistry such as monitoring of organic reaction using thin‐layer chromatography and UV, microwave (MW) technique for the synthesis, and column chromatography for the product isolation and structure determination through NMR, MS, and IR spectral analysis of the pure compounds.     

Improving the sensitivity of traditional Western blotting via Streptavidin containing Poly‐horseradish peroxidase (PolyHRP)

Immunoassays such as ELISAs and Western blotting have been the common choice for protein validation studies for the past several decades. Technical advancements and modifications are continuously being developed to enhance the detection sensitivity of these procedures. Among them, Streptavidin‐containing poly‐horseradish peroxidase (PolyHRP) based detection strategies have been shown to improve signals in ELISA. The use of commercially available Streptavidin and antibodies conjugated with many HRPs (PolyHRPs) to potentially enhance the detection sensitivity in Western blotting has not been previously investigated in a comprehensive manner. The use of PolyHRP‐secondary antibody instead of HRP‐secondary antibody increased the Western blotting sensitivity up to 85% depending on the primary antibody used. The use of a biotinylated secondary antibody and commercially available Streptavidin‐conjugated with HRP or PolyHRP all resulted in increased sensitivity with respect to antigen detection. Utilizing a biotinylated secondary antibody and Streptavidin‐conjugated PolyHRP resulted in as much as a 110‐fold increase in Western blotting sensitivity over traditional Western blotting methods. Quantification of troponin I in rat heart lysates showed that the traditional Western blotting method only detected troponin I in ≥2 μg of lysate while Streptavidin‐conjugated PolyHRP20 detected troponin I in ≥50 ng of lysate. A modified blocking procedure is also described that eliminated the interference caused by the endogenous biotinylated proteins. These results suggest that Streptavidin‐conjugated PolyHRP and PolyHRP secondary antibodies are likely to be commonly utilized for Western blots in the future.     

Underwater Electrical Discharges: Temperature,Density and Basic Instability Features with Different Anode Materials

Plasma Chemistry and Plasma Processing - Plasma temperature, density and arc dynamics have been investigated in underwater arc discharges under different anodic environments. Distinct differences...     

Compositional variation in 0.65 PbMg2/3Nb1/3O3 ‐0.35 PbTiO3 single crystals grown by high temperature solution growth technique

Single crystals of lead magnesium niobate titanate, 0.65 PbMg_2/3Nb_1/3O₃ (PMN) ‐0.35PbTiO₃ (PT) were grown using flux method near morphotropic phase boundary (MPB) composition. The crystals grown at the centre of the platinum crucible were found to PT deficient compared to those grown near the walls of the crucibles. A variation of ∼3.8 mol% in PT concentration was found in the crystals grown at the wall and at the centre of the crucible. The difference in the chemical composition of crystals grown at the centre and the near the wall of the crucible was observed by X‐ray diffraction, EDXRF, dielectric and thermal measurements. The presence of PT rich and deficient crystals is explained in terms of the segregation coefficient of PT in PMN. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electrical and optical properties of CdS nanocrystalline semiconductors

II‐VI semiconductor nanoparticles have recently attracted a lot of attention due to the possibility of their application in various devices. In the present study, chemical method has been used in synthesis of CdS nanoparticles and thiophenol was used as capping agent. X‐ray diffraction studies of both samples were done. The dc conductivity of CdS increases at a lower rate or is approximately constant upto 500K and thereafter the conductivity increases at a rapid rate. Beyond T_c it is seen that the portion of the σ_dc versus 1000/T is almost a straight line showing an Arrehenious behaviour. The dielectric constant of nanoparticles of CdS is found to be larger than the corresponding values of CdS crystals. It is clearly observed that at lower wavelengths nanocrystalline samples show a blue‐shift. The three peaks of sample (S2), A, Band C can be ascribed to the transition from Cd‐O complex donor formed by adsorbed oxygen to the valance band, Cd ‐ excess acceptor and the surface states, respectively. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fabrication and electrochemical performance of La<Subscript>0.5</Subscript>Sr<Subscript>0.5</Subscript>CoO<Subscript>3</Subscript> impregnated porous YSZ cathode

La_0.5Sr_0.5CoO₃-yttria-stabilized zirconia (LSCO-YSZ) composite cathode for solid oxide fuel cell (SOFC) has been fabricated by wet impregnation method. Nitrate precursors of La, Sr, and Co have been impregnated into the pre-sintered porous YSZ matrix, which is converted into LSCO phase after calcination at 850 °C in the presence of glycine as confirmed from X-ray diffraction. LSCO of 5, 7, and 10 wt% impregnated porous YSZ have been electrochemically characterized using 2-probe AC conductivity method. Maximum ionic conductivity of 0.27 S/cm at 800 °C and activation energy of 0.15 eV between 600 and 800 °C have been observed for 10 wt% LSCO-YSZ cathode. Area-specific resistance of 1.01 Ω cm² at 800 °C is estimated for the electrolyte-supported half-cell (10 wt% LSCO-YSZ/YSZ). After testing the LSCO-YSZ cathode matrix, the electrolyte-supported full cell (10 wt% LSCO-YSZ/YSZ/NiO-YSZ) has been tested and produced maximum power density 51.12 mW/cm² (109.38 mA/cm²) at 800 °C. The electrolyte-supported full cell exhibited 6 Ω cm² electrode polarization at 800 °C in H₂, which is in higher side leading to low performance. LSCO-YSZ/YSZ/NiO-YSZ SOFC found to give stable performance up to 2 h and scanning electron microscopy analysis has been carried out before and after cell testing to assess the morphological changes.