Stereochemical,biochemical and ligation behaviour of divalent platinum complexes of sulfur and nitrogen donor agents

Divalent Pt complexes of o-FC₆ H₄ C(H)NNC(SH)SCH₂ Ph(L¹H) and o-FC₆ H₄ C(Me)NNC(SH)SCH₂ Ph(L ²H) have been synthesized and characterized thoroughly by analytical data, conductance measurements, molecular weight determinations, magnetic measurements, i.r., electronic, ¹H-n.m.r. and ¹⁹F-n.m.r. spectral studies. The spectral data are consistent with a square planar geometry around Pt^IIin which the ligand acts as a neutral bidentate and monobasic bidentate ligand coordinating through nitrogen and sulfur atoms. Ligands and their metal complexes were tested against certain microorganisms to assess their antimicrobial properties and the results are indeed positive.     

Radon exhalation potential and natural radioactivity in soil collected from the surrounding area of a thermal power plant

Journal of Radioanalytical and Nuclear Chemistry - In the present study, radon (222Rn), thoron (220Rn) exhalation rates, and the specific activities of 238U,232Th, and 40K of 75 soil samples...     

A new intramolecular charge transfer receptor as a selective ratiometric ‘off-on’ sensor for Zn

A new intramolecular charge transfer (ICT) probe 3 is found to display a highly selective photophysical response in the presence of Zn²⁺, among various biologically significant metal ions examined. The absorption band of 3 is red shifted by 84 nm and the fluorescence intensity increases 13-fold in the presence of Zn²⁺. The binding interaction follows the order Zn²⁺ > Cd²⁺ > Mg²⁺ > Ba²⁺ > Ca²⁺ > K⁺ ≅ Na⁺ ≅ Li⁺ and the stability constant for 3 + Zn²⁺ is over an order of magnitude higher compared to biologically competing Ca²⁺ and Mg²⁺.     

Immobilization of Xylanase from <Emphasis Type="Italic">Bacillus pumilus</Emphasis> Strain MK001 and its Application in Production of Xylo-oligosaccharides

Xylanase from Bacillus pumilus strain MK001 was immobilized on different matrices following varied immobilization methods. Entrapment using gelatin (GE) (40.0%), physical adsorption on chitin (CH) (35.0%), ionic binding with Q-sepharose (Q-S) (45.0%), and covalent binding with HP-20 beads (42.0%) showed the maximum xylanase immobilization efficiency. The optimum pH of immobilized xylanase shifted up to 1.0 unit (pH 7.0) as compared to free enzyme (pH 6.0). The immobilized xylanase exhibited higher pH stability (up to 28.0%) in the alkaline pH range (7.0–10.0) as compared to free enzyme. Optimum temperature of immobilized xylanase was observed to be 8 °C higher (68.0 °C) than free enzyme (60.0 °C). The free xylanase retained 50.0% activity, whereas xylanase immobilized on HP-20, Q-S, CH, and GE retained 68.0, 64.0, 58.0, and 57.0% residual activity, respectively, after 3 h of incubation at 80.0 °C. The immobilized xylanase registered marginal increase and decrease in K _m and V _max values, respectively, as compared to free enzyme. The immobilized xylanase retained up to 70.0% of its initial hydrolysis activity after seven enzyme reaction cycles. The immobilized xylanase was found to produce higher levels of high-quality xylo-oligosaccharides from birchwood xylan, indicating its potential in the nutraceutical industry.     

Efficient Recycling of Gold and Copper from Electronic Waste by Selective Precipitation

The recycling of metals from electronic waste (e-waste) using efficient, selective, and sustainable processes is integral to circular economy and net-zero aspirations. Herein, we report a new method for the selective precipitation of metals such as gold and copper that offsets the use of organic solvents that are traditionally employed in solvent extraction processes. We show that gold can be selectively precipitated from a mixture of metals in hydrochloric acid solution using triphenylphosphine oxide (TPPO), as the complex [(TPPO)₄(H₅O₂)][AuCl₄]. By tuning the acid concentration, controlled precipitation of gold, zinc and iron can be achieved. We also show that copper can be selectively precipitated using 2,3-pyrazinedicarboxylic acid (2,3-PDCA), as the complex [Cu(2,3-PDCA-H)₂]_n ⋅ 2n(H₂O). The combination of these two precipitation methods resulted in the recovery of 99.5 % of the Au and 98.5 % of the Cu present in the connector pins of an end-of-life computer processing unit. The selectivity of these precipitation processes, combined with their straightforward operation and the ability to recycle and reuse the precipitants, suggests potential industrial uses in the purification of gold and copper from e-waste.     

Dual negative precursor ion scan approach for rapid detection of glutathione conjugates using liquid chromatography/tandem mass spectrometry

Screening for conjugates formed by the tripeptide glutathione with new chemical entities is an essential step during the drug discovery process, as the formation of these conjugates serves as an indicator for the presence of reactive electrophilic intermediates. To increase the selectivity and throughput of this analysis, various mass spectral scan types have evolved over time. Historically, samples were analyzed under positive ionization conditions for the neutral loss of m/z 129 (loss of the pyroglutamic acid moiety from glutathione); however, more recently, negative precursor ion scanning for the loss of m/z 272 (deprotonated gamma-glutamyl-dehydroalanyl-glycine from glutathione) has emerged as a more selective tool. Further increasing the selectivity, we report on an extension of this methodology by incorporating a simultaneous dual negative precursor ion scan for two commonly observed ion fragments from glutathione conjugates, m/z 272 and 254 (the dehydrated form of m/z 272). This negative dual precursor ion scan methodology was first validated using substrates known to undergo metabolic bioactivation (diclofenac, carbamazepine, and 3-methyl indole) and has then been applied to the routine analysis of proprietary compounds undergoing active lead optimization. In comparison to alternative scan methodologies, the increased selectivity offered by this simultaneous dual precursor method results in a reduction in the generation of false positive results as well as reduced data interpretation time.     

Synthesis of fluorescent carbon dots via microwave carbonization of citric acid in presence of tetraoctylammonium ion,and their application to cellular bioimaging

A jelly-like form of carbon dots (C-dots) was prepared by microwave-assisted synthesis from citric acid in the presence of tetraoctylammonium bromide. The effect of the concentration of tetraoctylammonium bromide was examined. The synthesized carbon dots were characterized by UV–vis, XRD, FTIR, fluorescence and HR-TEM. Fluorescence extends from 350 to 600 nm, and the corresponding excitation wavelengths range from 300 to 460 nm. Quantum yields are at around 0.11. A cytotoxicity study showed carbon dots to be cell permeable and biocompatible which renders them appropriate for imaging applications. The dots were used to image HeLa cell lines via the blue fluorescence of the dots.

C-dots were synthesized from citric acid by microwave heating in presence of varying concentrations of tetraoctylammonium bromide (TOAB) as a micellar template. The excellent optical properties of the nanoparticles make them well suitable for bio-imaging of HeLa cells.

     

Local and global universal relations for first-gradient materials

Local universal relations are relations between stress and kinematic variables which hold for all materials of a particular class irrespective of specific material parameters. A method is developed for obtaining local universal relations for most first gradient materials. The currently known local universal relations for isotropic elastic materials have been extended to all isotropic first gradient materials under constant step deformation histories and have also been extended to all isotropic first gradient materials undergoing arbitrary time dependent triaxial extensions along fixed material directions. It has been shown that universal relations exist for some anisotropic materials. A set of pseudo-universal relations has been obtained for anisotropic elastic materials which can be used to decouple the material functions. These pseudo-universal relations contain some, but not all, material functions. A global universal relation has been developed for the extension and torsion of an isotropic cylindrical shaft which holds for all incompressible first gradient materials.     

Quality control assessment of polyherbal formulation based on a quantitative determination multimarker approach by ultra high performance liquid chromatography with tandem mass spectrometry using polarity switching combined with multivariate analysis

An ultra high performance liquid chromatography with electrospray ionization tandem mass spectrometry method has been developed and validated for the simultaneous quantification of 28 major bioactive compounds in Mentat tablet, a complex Indian herbal medicine used in the treatment of neurological disorder and improvement of mental health. Multiple‐reaction monitoring scanning was employed for quantification in positive and negative ion switching mode. The analysis was accomplished on Waters ACQUITY UPLC BEH C₁₈ column with linear gradient elution of water/formic acid (0.1%) and acetonitrile/formic acid (0.1%) at a flow rate of 0.3 mL/min. The proposed method was validated with acceptable linearity (r², 0.9984–0.9999), precision (RSD, 0.22–2.11%), stability (RSD, 0.16–1.78%), and recovery (RSD ≤ 3.74%), under optimum conditions. The limits of quantitation ranged from 0.28 to 3.88 ng/mL. The method was successfully applied for simultaneous determination of 28 compounds in 20 batches of Mentat tablet. Hierarchical cluster analysis and principal component analysis were performed to evaluate the similarity and variation of the 20 samples based on the characteristics of 28 bioactive compounds. Results indicated that this method is rapid, sensitive, and reliable to show the quality of the Mentat tablet's composition, hence may be used for quality control of polyherbal formulations having similar markers/raw herbs.     

On New Similarity Solutions of the Boiti–Leon–Pempinelli System

In the present work, the new exact solutions of the Boiti-Leon-Pempinelli system have been found. The system has extensive physical background. The exact solutions of the Boiti-Leon-Pempinelli system are investigated using similarity transformation method via Lie group theory. Lie symmetry generators are used for constructing similarity variables for the given system of partial differential equations, which lead to the new system of partial differentiaJ equations with one variable less at each step and eventually to a system of ordinary differential equations （ODEs）. Finally, these ODEs are solved exactly. The exact solutions are obtained under some parametric restrictions. The elastic behavior of the soliton solutions is shown graphically by taking some appropriate choices of the arbitrary functions involved in the solutions.