Bose-Einstein correlations for pions produced inp p collisions at 360 GeV/c

Zeitschrift für Physik C Particles and Fields - Correlations among identically charged pions were measured for pions produced inp p collisions at 360 GeV/c using the EHS spectrometer. The...     

An efficient transient Navier–Stokes solver on compact nonuniform space grids

In this paper, we propose an implicit higher-order compact (HOC) finite difference scheme for solving the two-dimensional (2D) unsteady Navier–Stokes (N–S) equations on nonuniform space grids. This temporally second-order accurate scheme which requires no transformation from the physical to the computational plane is at least third-order accurate in space, which has been demonstrated with numerical experiments. It efficiently captures both transient and steady-state solutions of the N–S equations with Dirichlet as well as Neumann boundary conditions. The proposed scheme is likely to be very useful for the computation of transient viscous flows involving free and wall bounded shear layers which invariably contain spatial scale variation. Numerical results are presented and compared with analytical as well as established numerical data. Excellent comparison is obtained in all the cases.     

Ultra high vacuum electron spectrometer for ‘DSCEMS’

Depth Selective Conversion Electron Mössbauer Spectroscopy (DSCEMS) has become a very important surface science technique during the last one decade and attracted world wide interest specially because it gives more detailed knowledge of the properties and structure of the solid surfaces. The design and details of an ultra high vacuum cylindrical mirror analyser (CMA) for DSCEMS are described and illustrated.     

Polyaniline/Single‐Walled Carbon Nanotubes Composite Based Triglyceride Biosensor

Nanocomposite film comprising of polyaniline (PANI) and single walled carbon nanotubes (SWCNT) has been fabricated onto indium‐tin‐oxide (ITO) coated glass plate using electrophoretic technique. Co‐immobilization of glycerol dehydrogenase (GDH) and lipase (LIP) has been done via N‐ethyl‐N′‐(3‐dimethylaminopropyl) carbodiimide and N‐hydroxysuccinimide chemistry to explore its application for triglyceride (tributyrin) sensing. Response studies have been done using linear sweep voltammetry revealing that LIP‐GDH/PANI‐SWCNT‐TB/ITO bioelectrode can detect tributyrin in the range of 50 to 400 mg dL^?1 with low Michaelis–Menten constant of 1.138 mM, improved response time of 12 s, high sensitivity as 4.28×10^?4 mA mg^?1 dL and storage stability of about 13 weeks.     

Electrophoretically deposited polyaniline nanotubes based film for cholesterol detection

Polyaniline nanotube (PANI-NT) based films have been fabricated onto indium-tin-oxide (ITO) coated glass plates via electrophoretic technique. These PANI-NT/ITO electrodes have been utilized for covalent immobilization of cholesterol oxidase (ChOx) using glutaraldehyde (Glu) as cross-linker. Structural, morphological and electrochemical characterization of PANI-NT/ITO electrode and ChOx/Glu/PANI-NT/ITO bioelectrode have been done using FT-IR spectroscopy, SEM, electrochemical impedance spectroscopy and cyclic voltammetry techniques. Response studies of the ChOx/Glu/PANI-NT/ITO bioelectrode have been carried out using both linear sweep voltammetry and UV-Visible spectrophotometry. The results of the biosensing studies reveal that this bioelectrode can be used to detect cholesterol in wide detection range of 25-500 mg/dL with high sensitivity of 3.36 mA mg(-1) dL and fast response time of 30 s at pH 7.4. This bioelectrode exhibits very low value of Michaelis-Menten constant of 1.18 mM indicating enhanced interactions between cholesterol and ChOx immobilized onto this nanostructured PANI matrix.     

CoMFA and CoMSIA of diverse pyrrolidine analogues as dipeptidyl peptidase IV inhibitors: active site requirements

The inhibition of dipeptidyl peptidase IV (DPP-IV) has emerged as an attractive target in the treatment of type 2 diabetes. In view of this development, a critical analysis of structural requirements of the DPP-IV inhibitors is envisioned to identify the significant features toward design of selective inhibitors. The comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) contour plots of pyrrolidine based analogues are used to analyze the structural requirements of a DPP-IV active site. The CoMFA model has shown a cross-validated q ² of 0.651 with a non-cross-validated r ² of 0.882 and explained 70.6% variance in the activity of external test compounds. In this, the steric and electrostatic fields have respectively contributed 59.8 and 40.2%, respectively, to the explained activity of the compounds. The CoMSIA model has shown optimum predictivity (cross-validated q ² = 0.661; non-cross-validated r ² = 0.803; external test set’s predictive r ² = 0.706) with four molecular fields namely, steric, electrostatic, hydrogen bond (HB)-donor, and HB-acceptor. The contour plots of molecular fields resulting from these studies have suggested: (i) steric restriction with small electron rich substituent at 2- and 3-position of pyrrolidine ring, (ii) presence of electropositive ring linker between the pyrrolidine head and aryl tail, (iii) presence of electron-rich groups around the aryl tail moiety, and (iv) presence of sulfonamide between the ring linker and aryl tail which would increase DPP-IV binding affinity of the compounds. These findings will help in the design of structurally related/new compounds as potential DPP-IV inhibitors.     

Nanoengineering of methylene blue loaded silica encapsulated magnetite nanospheres and nanocapsules for photodynamic therapy

Core–shell nanostructures have emerged as an important class of functional materials with potential applications in diverse fields, especially in health sciences. In this article, nanoengineering of novel magnetic colloidal dispersion containing surface modifiable silica with a core of single domain magnetite nanoparticles loaded with photosensitizer (PS) drug “Methylene blue” (MB) has been described. Magnetite core is produced by the well-established chemical coprecipitation technique and silica shell is formed over it by the modified hydrolysis and condensation of TEOS (tetraethyl orthosilicate). Conditions for reaction kinetics have been established to tailor the core–shell structures in the form of nanospheres and nanocapsules. MB is loaded into the nanostructures by demethylation reaction. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated MB loaded superparamagnetic magnetite-silica nanostructures with tailored morphology, tunable loading, and excellent magnetic properties.     

Formation and stability criteria for amorphous Ge alloy films

Formation and stability of room-temperature deposited amorphous (a-) alloy films of Ge with Ag, Au, Cu, Ni, Fe, Ga, In, Sn, Sb, Ni, Bi and Nb have been studied, using differential thermal analysis and electron microscopy, as a function of various parameters such as: solubility of alloying element (in c-Ge), its melting point, atomic size and electonegativity. It has been shown that the composition range R, up to which amorphous alloy films are obtained, is affected by the solubility of the alloying element and its melting point. The effect of solubility S is dominant when S > 1 at%. However, for $\text{S ? 1}\text{at}\text{\%}$, the range is entirely governed by the melting point of the alloying element. Solubility and melting point have also been found to play a decisive role in stabilizing the amorphous phase of Ge. However, atomic size and electronegativity differences do not seem to play any important role in either the formation or stability of the amorphous phase.     

Discovery of novel inhibitors for <Emphasis Type="Italic">Leishmania</Emphasis> nucleoside diphosphatase kinase (NDK) based on its structural and functional characterization

Nucleoside diphosphate kinases (NDKs) are ubiquitous enzymes that catalyze the transfer of the γ-phosphate moiety from an NTP donor to an NDP acceptor, crucial for maintaining the cellular level of nucleoside triphosphates (NTPs). The inability of trypanosomatids to synthesize purines de novo and their dependence on the salvage pathway makes NDK an attractive target to develop drugs for the diseases they cause. Here we report the discovery of novel inhibitors for Leishmania NDK based on the structural and functional characterization of purified recombinant NDK from Leishmania amazonensis. Recombinant LaNDK possesses auto-phosphorylation, phosphotransferase and kinase activities with Histidine 117 playing an essential role. LaNDK crystals were grown by hanging drop vapour diffusion method in a solution containing 18% PEG-MME 500, 100 mM Bis-Tris propane pH 6.0 and 50 mM MgCl₂. It belongs to the hexagonal space group P6₃22 with unit cell parameters a?=?b?=?115.18, c?=?62.18 Å and α?=?β?=?90°, γ?=?120°. The structure solved by molecular replacement methods was refined to crystallographic R-factor and R_free values of 22.54 and 26.52%, respectively. Molecular docking and dynamics simulation-based virtual screening identified putative binding compounds. Protein inhibition studies of selected hits identified five inhibitors effective at micromolar concentrations. One of the compounds showed ~45% inhibition of Leishmania promastigotes proliferation. Analysis of inhibitor-NDK complexes reveals the mode of their binding, facilitating design of new compounds for optimization of activities as drugs against leishmaniasis.     

Review of heat transport properties of solar heat transfer fluids

The present article reviews the test techniques for some of the important heat transport properties of oils such as viscosity, density, specific heat capacity and thermal conductivity mainly used for characterization of heat transfer fluids. It can be seen that while density of oils can be tested at higher temperatures, the other heat transport properties of oils like viscosity, specific heat capacity and thermal conductivity have a limitation of being tested at low temperatures below 100–150 °C. While quite a few number of researchers have reported evaluation of heat transfer properties like specific heat capacity and thermal conductivity of oils by different methods, there remains a huge scope of debate and discussions on the repeatability and reproducibility of such tests, especially in case of oils used in high-temperature applications. A lot of insight has been gathered with respect to testing of thermal conductivity of oils, and several common test methods have been compared with each other. Lastly, two mathematical models, reported in the literature in open domain, have been reviewed and compared with each other. If the oils are to be used at elevated temperatures, like heat transfer fluids used in concentrated solar power generation where temperatures go as high as 400 °C and beyond, there is an urgent need to standardize a laboratory test method for performance evaluation of heat transport properties, which can help in formulating new generation oils based on novel chemistries and technologies like nanofluids, synthetic oils of novel chemistries, molten salts and molten metals.