Antibiofilm Activity of α-Amylase from Bacillus subtilis S8-18 Against Biofilm Forming Human Bacterial Pathogens

The extracellular α-amylase enzyme from Bacillus subtilis S8-18 of marine origin was proved as an antibiofilm agent against methicillin-resistant Staphylococcus aureus (MRSA), a clinical strain isolated from pharyngitis patient, Vibrio cholerae also a clinical isolate from cholera patient and Pseudomonas aeruginosa ATCC10145. The spectrophotometric and microscopic investigations revealed the potential of α-amylase to inhibit biofilm formation in these pathogens. At its BIC level, the crude enzyme caused 51.81–73.07% of biofilm inhibition. Beyond the inhibition, the enzyme was also effective in degradation of preformed mature biofilm by disrupting the exopolysaccharide (EPS), an essential component in biofilm architecture. Furthermore, the enzyme purified to its homogeneity by chromatographic techniques was also effective in biofilm inhibition (43.83–61.68%) as well as in degradation of EPS. A commercial α-amylase enzyme from B. subtilis was also used for comparative purpose. Besides, the effect of various enzymes and temperature on the antibiofilm activity of amylase enzymes was also investigated. This study, for the first time, proved that α-amylase enzyme alone can be used to inhibit/disrupt the biofilms of V. cholerae and MRSA strains and beholds much promise in clinical applications.     

Highly Sensitive NH(3) Detection Based on Organic Field-Effect Transistors with Tris(pentafluorophenyl)borane as Receptor

We have increased organic field-effect transistor (OFET) NH(3) response using tris(pentafluorophenyl)borane (TPFB) as a receptor. OFETs with this additive could detect concentrations of 450 ppb v/v, with a limit of detection of 350 ppb, the highest sensitivity reported to date for semiconductor films; in comparison, when triphenylmethane (TPM) or triphenylborane (TFB) was used as an additive, no obvious improvement in the sensitivity was observed. These OFETs also showed considerable selectivity with respect to common organic vapors and stability toward storage. Furthermore, excellent memory of exposure was achieved by keeping the exposed devices in a sealed container stored at -30 °C, the first such capability demonstrated with OFETs.     

Electrochemical supercapacitor studies of hierarchical structured Co2+-substituted SnO2 nanoparticles by a hydrothermal method

Hierarchical structured Co-doped SnO₂ nanoparticles are prepared by a low temperature hydrothermal process. The structural and surface morphologies of the SnO₂ and Sn_1?xCo_xO₂ nanoparticles are studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The Sn_1?xCo_xO₂ nanoparticles form with a tetragonal rutile structure during the hydrothermal process without further calcination. The pseudocapacitance behavior of the Sn_1?xCo_xO₂ nanoparticles is characterized by cyclic voltammetry (CV) in 1.0 M H₂SO₄ electrolyte. The specific capacitance (SC) is found to increase with an increase in cobalt content. A maximum SC of 840 F g^?1 is obtained for a Sn_0.96Co_0.04O₂ composite at a 10 mV s^?1 scan rate.     

Low-temperature synthesis of Zn2SiO4:Mn green photoluminescence phosphor

Zn₂SiO₄:Mn green phosphor having comparable photoluminescence (PL) efficiency with commercial phosphor has been synthesized at 1000 °C using solid state reactions involving ZnO, silicic acid and manganese acetate. The water of crystallization attached to SiO₂ in silicic acid whose dissociation at 1000 °C seem to promote the sintering efficiency of Zn₂SiO₄:Mn. Incremental ZnO addition and re-firing at 1000 °C promote the diffusion rate of ZnO and SiO₂. The formation of a single crystalline phase of willemite structure in the samples was confirmed by powder XRD measurements. The phosphor exhibit an intense excitation band centered around 275 nm and a relatively weak excitation centered around 380 nm while the broad band green emission peaks at 524 nm. Other parameters studied include PL spectra, grain morphology, ZnO/SiO₂ molar ratio, Mn concentration, co-dopant/flux and the effect of chemical forms of Mn dopant as well as silica on the PL efficiency.     

Synthesis and characterization of ZnCo2O4 nanomaterial for symmetric supercapacitor applications

ZnCo₂O₄ nanomaterial was prepared by co-precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge–discharge tests at various current densities. It is shown that the crystal structure and surface morphology play an important role in the enhancement of the specific capacitance. The TEM results clearly indicate that the prepared material shows aggregated particles. The particle size powder was about 50 nm, and SEM pictures indicate a porous morphology. The electrochemical behavior of ZnCo₂O₄ was characterized by mixing equal proportion of carbon nanofoam (CNF). From CV, it is concluded that the combination of redox and pseudo-capacitance increases the specific capacitance up to 77 F g⁻¹ at 5 mV s⁻¹ scan rate. The ZnCo₂O₄-based supercapacitor cell has good cyclic stability and high coulombic efficiency.     

Synthesis and characterization of Li<Subscript>1-x</Subscript>Tb<Subscript>x</Subscript>NiPO<Subscript>4</Subscript> solid solution as cathode materials for lithium ion battery application

Modified Pechini-type polymerizable precursor method has been used to prepare nanosized Li_1-xTb_xNiPO₄ (x = 0, 0.03, 0.05, and 0.07) solid solutions to obtain homogeneous with controlled stoichiometry and smaller particle size. The reaction temperature was determined by thermogravimetric (TG/DTA) analysis. X-ray diffraction analysis reveals the formation of orthorhombic structure and the calculated crystallite sizes are found to be in the range of 75–89 nm. Morphological, compositional, and vibrational properties were performed by SEM, EDAX, and FTIR, respectively. Conductivity measurements were carried out at room temperature by AC impedance analysis. The Li_0.97Tb_0.03Ni_0.99PO₄ sample shows one order of higher conductivity than pure LiNiPO₄. Higher concentration of terbium samples such as Li_0.95Tb_0.05Ni_0.99PO₄ and Li_0.93Tb_0.07Ni_0.99PO₄ lead to decrease of conductivity. The frequency dependency of dielectric permittivity, dielectric loss, and electric modulus of Li_1-x Tb_xNiPO₄ solid solutions are studied. The frequency-dependent plot of modulus reveals that the conductivity relaxation is of non-Debye type.     

Effective Correlation of Two Holes in a Semimagnetic Quantum Well Wire: Influence of Shape of Confining Potential on Coulomb Interaction *

The hole-hole interaction $(E_{hh})$ has been considered in a ${\rm{CdTe /Cd}}_{1-x}{\rm {Mn}}x{\rm {Te}}$ Semimagnetic Quantum Well Wire (SQWW). The influence of the shape of the confining potential like square well and parabolic well type on the binding energy of an acceptor impurity with two holes and their Coulomb interaction between them has been studied for various impurity locations. Magnetic field has been used as a probe to understand the carrier-carrier correlation in such Quasi 1-Dimensional QWW since it alters the strength of the confining potential tremendously. In order to show the significance of the correlation between the two holes, the calculations have been done with and without including the correlation effect in the ground state wavefunction of the hyderogenic acceptor impurity and the results have been compared. The expectation value of the Hamiltonian, ${H}$, is minimized variationaly in the effective mass approximation through which $(E_{hh})$ has been obtained.     

Neutrino cross-section in ultrahigh energy regime using double asymptotic limit of QCD

Some unusual and unexplained events (the so-called Kolar events) were interpreted in Pramana – J. Phys. 82, 609 (2014). This article is a corrigendum to it.     

ZnS/SnS/Ag2S photocatalyst with enhanced photocatalytic activity under visible light illumination towards wastewater treatment

Research on Chemical Intermediates - In this study, various compositions of ternary ZnS/SnS/Ag2S nanocatalysts were prepared for the first time through a wet chemical method. The as-prepared...     

Linear solvation energy relationship of the solubility of very polar gases: Sulfur dioxide,hydrogen chloride,hydrogen bromide,and ammonia

A linear free energy relationship was found for the log (mole fraction) of solutes in a wide variety of organic solvents with the solvatochromic parameters and the Hildebrand solubility parameter. The solutes were the highly dipolar gases sulfur dioxide, hydrogen chloride, hydrogen bromide, and ammonia at 25°C and 1 atm. partial pressure of the solute. It was found that correlations were greatly improved if solvatochromic parameters for the solvent as a monomer were used rather than the values for the bulk solvent. In solutions with these very dipolar gases, the mole ratio of solute to solvents approaches unity in many of the solutions, so a molecule of solute is interacting primarily with a particular molecule of the solvent. Therefore, the use of the solvatochromic parameters for the solvent as monomer is physically reasonable.