Salt-tolerant and thermostable alkaline protease fromBacillus subtilis NCIM No. 64

The proteolytic activity produced by aBacillus subtilis isolated from a hot spring was investigated. Maximum protease production was obtained after 38 h of fermentation. Effects of various carbon and nitrogen sources indicate the requirement of starch and bacteriological peptone to be the best inducers for maximum protease production. Requirement for phosphorus was very evident, and the protease was secreted over a wide range of pH 5–11. The partially purified enzyme was stable at 60°C for 30 min. Calcium ions were effective in stabilizing the enzyme, especially at higher temperature. The enzyme was extremely salt tolerant and retained 100% activity in 5M NaCl over 96 h. The molecular weight of the purified enzymes as determined by SDS-PAGE was 28,000. The enzyme was completely inactivated by PMSF, but little affected by urea, sodium dodecyl sulfate, and sodium tripoly phosphate.     

Deep inelastic collisions of32S +27Al reaction at 130 MeV bombarding energy

The³²S +²⁷Al reaction was studied to investigate the deep inelastic collisions at a bombarding energy of 130 MeV which is well above the Coulomb barrier. The energy distributions of the binary decay products of 6⩽Z⩽10 were determined using a large area position sensitive ionization chamber. The average kinetic energies of the reaction products indicate that the exit shapes correspond to highly stretched scission configurations in the deep-inelastic processes.     

Magnetoelectric effect in cobalt ferrite-barium titanate composites and their electrical properties

CoFe₂O₄-BaTiO₃ composites were prepared using conventional ceramic double sintering process with various compositions. Presence of two phases in the composites was confirmed using X-ray diffraction. The dc resistivity and thermoemf as a function of temperature in the temperature range 300 K to 600 K were measured. Variation of dielectric constant (ɛ′) with frequency in the range 100 Hz to 1 MHz and also with temperature at a fixed frequency of 1 kHz was studied. The ac conductivity was derived from dielectric constant (ɛ′) and loss tangent (tan δ). The nature of conduction is discussed on the basis of small polaron hopping model. The static value of magnetoelectric conversion factor has been studied as a function of magnetic field.     

Optical energy balance in laser-produced plasmas

Optical energy balance in plasmas produced by irradiating solid targets by highpower laser pulses, has been experimentally determined. The total light scattered has been measured as a function of the laser intensity and the irratiated spot diameter. It has been found that the net light absorption does not depend on the laser intensity alone, but is also affected by the irradiated spot area. It has also been observed that diffuse back reflection becomes a dominant loss mechanism at high incident flux and small irradiated spot area.     

Aminolysis of p-tert-butyltetrathiacalix[4]arene tetraethylacetates in cone, partial cone and 1,3-alternate conformation: synthesis of amide based receptors for oxyanions

Cone, partial cone and 1,3-alternate conformers of tetrathiacalix[4]arene tetraethylacetate were synthesized and subjected to aminolysis with alkyl amines [CH₃(CH₂)_nNH₂; n=2, 3, 5] to yield mono-, di-, tri- or tetrasubstituted p-tert-butyltetrathiacalix[4]arene amides which were characterized by detailed analysis of their NMR spectral and single crystal X-ray crystallography. It has been observed that while the 1,3-alternate and cone conformers of the tetrathiacalix[4]arene tetraethylacetate gave corresponding tetrathiacalix[4]arene tetraamides under different experimental conditions, the corresponding partial cone conformer undergoes a cascade of regioselective reactions with the same amines. Variable temperature ¹H NMR experiments allowed the determination of relative stability of different conformers within the temperature range of 298-333 K. The synthesized derivatives were evaluated as molecular extractants for cations and anions and were determined to facilitate extraction of oxyanions (CrO₄²⁻ and Cr₂O₇²⁻) from aqueous to the organic phase. The studies have a significance in the design of tetrathiacalix[n]arene based molecular receptors for innovative applications.     

Polyglycerol‐Based Copper Chelators for the Transport and Release of Copper Ions in Biological Environments

Here, the synthesis and characterization of three improved nanosystems is presented based on amino functionalized hyperbranched polyglycerol (hPG; M_w = 16.8 kDa) as potential copper(ii ) chelators. The ligands, N‐methyl‐N‐picolylglycine amide, 2,6‐pyridine dicarboxylic acid monoamide, and cyclam tetraacetic acid (TETA) monoamide, are covalently attached to the polymer with amide bonds. In this paper, the Cu(ii ) loading capacity, the stability of the Cu(ii )‐loaded carriers at different pHs, with competing ligands and in human serum, as well as the transport of Cu(ii ) in biological systems are investigated. For the first time, a different cytotoxicity of functionalized polymer nanoparticles with and without Cu(ii ) is observed. The cyclam‐based carrier combines the highest loading capacity (29 Cu ions/nanoparticle), best stability with respect to pH and EDTA (45% remaining Cu after 24 h), lowest cytotoxicity (IC₅₀ > 100 × 10^?6m (unloaded), 1500 × 10^?6m Cu(ii ); Cu:carrier 29:1), and the highest stability in human serum.

     

Mesoporous Porphyrin-Silica Nanocomposite as Solid Acid Catalyst for High Yield Synthesis of HMF in Water

Solid acid catalysts occupy a special class in heterogeneous catalysis for their efficiency in eco-friendly conversion of biomass into demanding chemicals. We synthesized porphyrin containing porous organic polymers (PorPOPs) using colloidal silica as a support. Post-modification with chlorosulfonic acid enabled sulfonic acid functionalization, and the resulting material (PorPOPS) showed excellent activity and durability for the conversion of fructose to 5-hydroxymethyl furfural (HMF) in green solvent water. PorPOPS composite was characterized by N₂ sorption, FTIR, TGA, CHNS, FESEM, TEM and XPS techniques, justifying the successful synthesis of organic networks and the grafting of sulfonic acid sites (5 wt%). Furthermore, a high surface area (260 m²/g) and the presence of distinct mesopores of ~15 nm were distinctly different from the porphyrin containing sulfonated porous organic polymer (FePOP-1S). Surprisingly the hybrid PorPOPS showed an excellent yield of HMF (85%) and high selectivity (>90%) in water as compared to microporous pristine-FePOP-1S (yield of HMF = 35%). This research demonstrates the requirement of organic modification on silica surfaces to tailor the activity and selectivity of the catalysts. We foresee that this research may inspire further applications of biomass conversion in water in future environmental research.     

Spatial trends in uranium distribution in groundwaters of Southwest Punjab,India - A hydrochemical perspective

A hydrochemical study was undertaken in uranium impacted districts of southwest Punjab for evaluating the spatial and vertical trends as well as correlations with other hydrochemical parameters. Results infer that U is present in all samples (12.2–621 µg l⁻¹) and 90% are contaminated. Contour diagram depicts contamination in entire region excepting some pockets in central part of the study area. Shallow zones (<50 m bgl) show higher U compared to deeper ones. Hydrochemistry infers a common source of U for both shallow and deep zones and alkalinity as the governing factor for U mobilization from the sediments.

     

Synthesis and evaluation of novel tetrapropoxycalix[4]arene enones and cinnamates for protection from ultraviolet radiation

A series of novel calix[4]arene enones (5-7) and cinnamates (12-14) have been synthesized and evaluated for ensuring protection from ultraviolet radiation (UVR). Spectroscopic analyses has revealed that compound 6 absorbs ultraviolet radiations between 280 and 350 nm with an absorption maximum at 312 nm. Its molar absorption coefficient (ε) (>5 × 10(4)M(-1)cm(-1)) and bandwidth are larger than those for the commercially used sun protectants (oxybenzone (OB), 2-ethylhexyl 4-methoxycinnamate (OMC) and avobenzone). The in vitro Sun Protection Factor (SPF) measurement revealed an SPF of 5.2 at 2% concentration of 6 in home made emulsion formulations while combination of 2% each of 6 and OMC gave an SPF of 8.8. Lower sun protection seems to be compensated by significant protection from more harmful UVA radiations (UVA/UVB absorbance ratio of 0.62).