Study on the spatial distribution of 137Cs content in bottom sediment and benthic species of Mumbai off coast

The observed ¹³⁷Cs content in bottom sediment and benthic species of Mumbai off coast varied between 2–370  \( {\text{Bq kg}}_{{ ( {\text{dry)}}}}^{ - 1} \) and <0.08–0.4  \( {\text{Bq kg}}_{{ ( {\text{wet)}}}}^{ - 1} \) respectively. The annual estimated ingestion dose to ‘general public’ due to consumption of benthic species is 0.02 µSv y^?1, which is infinitesimally smaller, in comparison to average annual human exposure of 3.01 mSv and also to the internationally accepted public dose limit of 1,000 µSv y^?1.     

Purification and Characterization of RNA Allied Extracellular Tyrosinase from Aspergillus Species

Production of l-DOPA, an anti-Parkinson’s drug, using biological sources is widely studied in which tyrosinase is known to play a vital role. Tyrosinase is an omnipresent type 3 copper enzyme participating in many essential biological functions. Understanding properties of tyrosinase is essential for developing useful tyrosinase-based applications. Hence, extracellular tyrosinase from Aspergillus flavus UWFP 570 was purified using ammonium sulphate precipitation and DEAE ion exchange chromatography up to 8.3-fold. Purified protein was a riboprotein in nature containing significant amount of RNA which was confirmed colorimetrically and by electrophoresis. Removal of RNA reduced the activity and altered the conformation of tyrosinase as suggested by spectroflurometric results. Optimum pH and temperature of this 140 kDa protein were 7 and 40 °C, respectively. Copper sulphate and magnesium chloride enhanced the activity whereas in contrast FeCl₃ inhibited the activity completely. Purified tyrosinase transformed l-tyrosine (5 mM) to l-DOPA within 5 h.     

Searching of potential energy curves for the benzene dimer using dispersion-corrected density functional theory

The present work aims to establish the utility of dispersion-corrected density functional theory for potential energy curves of the benzene dimer, a problem that has received significant attention for a long time. The interaction energies of parallel-stacked, T-shaped and parallel-displaced benzene dimer configurations have been evaluated using both dispersion- and normal gradient-corrected Perdew-Burke-Ernzerhof functionals along with Dunning's augmented correlation-consistent polarized valence triple-zeta (aug-cc-pVTZ) basis functions and compared with explicit correlation methods. The potential energy curves for the parallel-stacked and parallel-displaced benzene dimers are in excellent agreement with highly accurate coupled cluster (CCSD(T)) results, while for the T-shaped benzene dimer the dispersion-corrected results show a distinct deviation, being closer in that case to the MP2 level of results. The overestimation of interaction energy in the T-shaped dimer may be attributed to the presence of a permanent dipole moment in this configuration and indicates a structural dependence of the dispersion-corrected density functional method.     

Synthesis, gene silencing, and molecular modeling studies of 4'-C-aminomethyl-2'-O-methyl modified small interfering RNAs

The linear syntheses of 4'-C-aminomethyl-2'-O-methyl uridine and cytidine nucleoside phosphoramidites were achieved using glucose as the starting material. The modified RNA building blocks were incorporated into small interfering RNAs (siRNAs) by employing solid phase RNA synthesis. Thermal melting studies showed that the modified siRNA duplexes exhibited slightly lower T(m) (～1 °C/modification) compared to the unmodified duplex. Molecular dynamics simulations revealed that the 4'-C-aminomethyl-2'-O-methyl modified nucleotides adopt South-type conformation in a siRNA duplex, thereby altering the stacking and hydrogen-bonding interactions. These modified siRNAs were also evaluated for their gene silencing efficiency in HeLa cells using a luciferase-based reporter assay. The results indicate that the modifications are well tolerated in various positions of the passenger strand and at the 3' end of the guide strand but are less tolerated in the seed region of the guide strand. The modified siRNAs exhibited prolonged stability in human serum compared to unmodified siRNA. This work has implications for the use of 4'-C-aminomethyl-2'-O-methyl modified nucleotides to overcome some of the challenges associated with the therapeutic utilities of siRNAs.     

Energy pooling in multiple ionization and Coulomb explosion of clusters by nanosecond-long, megawatt laser pulses

We report the results of experiments that establish the possibility of bringing about multiple ionization and Coulomb explosion of molecular clusters with nanosecond laser pulses at intensities as small as 10(9) W cm(-2). We demonstrate several new facets of the laser-cluster interaction in the low-intensity, long-pulse domain: (i) The choice of laser wavelength for a given cluster species is very crucial. (ii) Excited electronic states play a very important role in the ionization dynamics. (iii) When field ionization is insignificant and ponderomotive energies are very small, it is energy pooling rather than inverse bremsstrahlung that determines how clusters absorb energy from the optical field.     

Physical features of ultrasound assisted enzymatic degradation of recalcitrant organic pollutants

This work has attempted to provide answer to the interaction of sonolysis and enzymatic treatment on degradation of recalcitrant dyes in a combined treatment. The model system comprises of two dyes, acid red and malachite green as model pollutants, along with horseradish peroxidase as a model enzyme and ultrasound of 20 kHz frequency. A dual approach of coupling experimental results with simulations of cavitation bubble dynamics has been adopted. Utilization of oxidation potential of horseradish peroxidase has been found to be a function of convection level in the medium. Cavitation phenomenon is found to have an adverse effect on enzyme action due to generation of high amplitude shock waves, which denature the enzyme. Degradation of dye at high static pressure increases due to absence of cavitation and high energy interaction (or collisions) between enzyme and dye molecules, which are beneficial towards enzymatic oxidation of the latter. High intensity convection generated by ultrasound also obviates need for an external shielding agent such as PEG that prevents attachment of the phenoxy radicals to enzyme that blocks the active sites of the enzyme.     

Quantitative determination of saroglitazar,a predominantly PPAR alpha agonist,in human plasma by a LC–MS/MS method utilizing electrospray ionization in a positive mode

A sensitive LC–MS/MS method was developed and validated for quantitation of saroglitazar using turboion spray interface with positive ion mode. A liquid–liquid extraction, with a mixture of dichloromethane and diethyl ether, was employed for the extraction of saroglitazar and glimepiride (IS) from human plasma. The chromatographic separation was achieved using an ACE‐5, C₁₈ (4.6 × 100 mm) column with a gradient mobile phase comprising acetonitrile and ammonium acetate buffer with trifluoracetic acid in purified water. Both analytes were separated within 10 min with retention times of 4.52 and 2.57 min for saroglitazar and IS, respectively. Saroglitazar quantitation was achieved by the summation of two MRM transition pairs (m/z 440.2 to m/z 366.0 and m/z 440.2 to m/z 183.1), while that of IS was achieved using transition pair m/z 491.3 to m/z 352.0. The calibration standards of saroglitazar showed linearity from 0.2 to 500 ng/mL, with a lower limit of quantitation of 0.2 ng/mL. The biases for inter‐ and intra‐batch assays were ?7.51–1.15% and ?11.21 to ?3.25%, respectively, while the corresponding precisions were 5.04–8.06% and 1.53–7.68%, respectively. The developed method was used to monitor the plasma concentrations of saroglitazar in clinical samples.