Elemental profile in some common medicinal plants of India. Its correlation with traditional therapeutic usage

Several parts of plants are used in herbal and Ayurvedic medicines of India. The different elemental constituents at trace levels of these plant parts play an effective role in the medicines prepared. Elemental composition of different parts (root, bark, leaf, seed) of some medicinal plants of North Eastern India has been determined by using proton induced X-ray emission (PIXE). A total of 14 elements, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, Zr and Pb have been measured. Their concentrations were found to vary in different samples. Medicinal properties of these plant samples and their elemental distribution have been correlated.     

Adsorption of Cr(VI) and Se(IV) from their aqueous solutions onto Zr4+-substituted ZnAl/MgAl-layered double hydroxides: effect of Zr4+ substitution in the layer

Hydrotalcite-like compounds (layered double hydroxides, LDHs) containing varying amounts of Al(3+), Zr(4+), and Zn(2+) or Mg(2+) in the metal hydroxide layer have been synthesized and characterized by various physicochemical methods. The adsorption behavior of uncalcined (as-synthesized) and calcined LDHs have been investigated for Cr(2)O(7)(2-) and SeO(3)(2-). The mixed oxides, obtained on calcination at 450 degrees C, exhibit high adsorption capacities for Cr(2)O(7)(2-) (1.6-2.7 meq/g) and SeO(3)(2-) (1.1-1.5 meq/g), where adsorption occurs through rehydration. Substitution of Zr(4+) in the LDHs, for either M(2+) or Al(3+) ions, increases the adsorption capacity up to 20%, thus providing an alternative way to enhance the adsorption capacity of this type of material. The high adsorption capacity of these materials could be successfully used for removal of undesirable anions from water and also for synthesis of intercalated materials with tailored acidobasicity.     

TDPAD measurements of magnetic hyperfine field for <Superscript>132</Superscript>Ba in ferromagnetic Ni

The magnetic hyperfine field of Ba in ferromagnetic Ni has been measured by time differential perturbed angular distribution technique using the 13 ns 10⁺ isomeric state in ¹³²Ba as probe which was populated in the reaction ¹²C(¹²⁴Sn, 4n) ¹³²Ba at beam energy of 60 MeV. The hyperfine field extracted from the observed Larmor precession frequency comes out to be ?84(5) kG. Our experimental results show good agreement with theoretical calculations performed within local density approximation of the density functional theory. The hyperfine field data presented here would be useful towards accurate determination of g-factor in other high spin states in Ba isotopes.     

High spin spectroscopy of 139Pr

The high spin states in N=80 ¹³⁹Pr have been investigated by in-beam γ-spectroscopic techniques following the reaction ¹³⁰Te (¹⁴N, 5n) reaction at E=75 MeV, using a gamma detector array, consisting of seven 23% compton-suppressed high purity germanium detectors and a multiplicity ball of fourteen bismuth germanate elements. Based on γ-γ coincidence data, the level scheme of ¹³⁹Pr has been considerably extended up to 7.2 MeV excitation. Tentative spin-parity assignments are done for the newly proposed levels on the basis of the DCO ratios corresponding to strong gates and the available information from the earlier light ion experiments.     

Bacterial synthesized metal and metal salt nanoparticles in biomedical applications: An up and coming approach

In the present scenario, metal nanoparticles have elicited a great deal of interest in biomedical applications because of their unique properties and antimicrobial potentials. Over the past few years, the green nanotechnology has materialized as a momentous approach for the synthesis and fabrication of noble metal salt and metal nanoparticles. The green route synthesis exploits diverse reducing and stabilizing agents from bacterial resources for the successful synthesis of metal nanoparticles. This review mainly focuses on the biosynthesis of the most commonly studied metal and metal salt nanoparticles such as gold, silver, platinum, palladium, copper, cadmium, titanium oxide, zinc oxide, zinc sulphate, cadmium sulphide and many more. These noble nanoparticles can be exploited in pharmaceutical industry as antimicrobial and anti-biofilm agents, targeted delivery of anticancer drugs, biosensors, etc.     

Impact of Membrane Types and Catalyst Layers Composition on Performance of Polymer Electrolyte Membrane Fuel Cells

Performance of a low temperature polymer electrolyte membrane fuel cell (PEMFC) is highly dependent on the kind of catalysts, catalyst supports, ionomer amount on the catalyst layers (CL), membrane types and operating conditions. In this work, we investigated the influence of membrane types and CL compositions on MEA performance. MEA performance increases under all practically relevant load conditions with reduction of the membrane thickness from 50 to 15 μm, however further decrease in membrane thickness from 15 to 10 μm leads to reduction in cell voltage at high current loads. A thick anode CL is found to be beneficial under wet operating conditions assuming more pore space is provided to accommodate liquid water, whereas under dry operating conditions, an intermediate thickness of the anode CL is beneficial. When studying the impact of catalyst layer thickness, too thin a catalyst layer again shows reduced performance due to increased ohmic resistance ruled out the performance of the MEAs which have identical Pt crystallite sizes on the cathode CLs i. e. the thinnest the cathode CL, the highest the voltage were achieved at a defined current load. Adaptation of the operating conditions is highly anticipated to achieve the highest MEA performance.     

A potential Co36Fe36Si4B20Nb4 nanocrystalline alloy for high temperature soft magnetic applications

The paper addresses the structural, crystallization, soft magnetic and Curie temperature behaviour of Co₃₆Fe₃₆Si₄B₂₀Nb₄ alloy. The material, prepared in the form of ribbons by melt-spinning technique, was amorphous in the as-cast state. Differential scanning calorimetry (DSC) showed two stages of crystallization whereas thermal variation of electrical resistivity (TER) carried out to a higher range of temperature indicated three stages of crystallization. The first crystallization stage, which occurred at 845?K and 825?K in DSC and TER, respectively, was due to the formation of nanophase (CoFe)₂Si as evidenced by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The formation of these nanoparticles reduced the magnetocrystalline anisotropy, thereby revealing good soft magnetic properties in the samples annealed between 825?K and 875?K with coercivity less than 49.9?A?m^?1 (627?mOe) and susceptibility?～?0.72?×?10³. In this optimum nanocrystalline state, the material also exhibited a high Curie temperature above 1100?K, opening the scope of the present nanocrystalline alloy for high temperature applications.     

Semileptonic (Λ b → Λcev) decay in a field theoretic quark model

The semileptonic decay width of heavy baryons such as (Λ _b → Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution inside the hadron as free parameters.     

Properties of 80-MeV oxygen ion irradiated ZnS:Mn nanoparticles and exploitation in nanophotonics

ZnS:Mn nanoparticles of size variation 11–17 nm were synthesized by a simple and inexpensive chemical method and confirmed by transmission electron microscopy (TEM). Presuming electronic energy loss (S _e>S _n, S _n being nuclear energy loss) to be the dominant phenomenon, they were irradiated by 80-MeV energetic oxygen ions with fluence of 10¹¹ to 10¹³ ions/cm². Photoluminescence (PL) spectra revealed three major emission bands ~445 nm, ~582 nm and ~706 nm; which are ascribed to D–A pair transition, Mn emission and surface state led fluorescence activation. The recovery of Mn emission and tunable surface state emission have been observed with ion fluence variation. Infra-red (IR) spectra of irradiated samples show great extent of oscillation with respect to amplitude due to ion fluence variation however, phonon energy (~98 MeV) remains unchanged. The possible applications of these modified properties in nanophotonics are also highlighted.