Magic angle spinning NMR on single crystals as a new aid in characterizing phase transitions: application to squaric acid

Accurate measurement of δ_ISO, the isotropic part of the NMR chemical shift tensor, is usually difficult for solids. This study suggests that the technique of magic angle sample spinning (MAS), employing single crystals, might be suitable for this purpose. In our ¹³C CP(cross polarization)/MAS measurements on squaric acid (H₂C₄O₄), single crystals yielded about five-fold narrower line widths than powder samples. The resolution enhancement thus obtained enabled us to measure δ_ISO for all four carbons of squaric acid, and to show that the average O-H distance can serve as an order parameter for the phase transition at 373 K. Additionally, the ¹³C δ_ISO data suggest that the transition mechanism involves a significant displacive component, in addition to the known order-disorder behavior, thus demonstrating the high potential of the single crystal MAS-NMR methodology for studying the microscopic mechanism of phase transitions.     

Enantioseparation of (RS)-Bupropion and determination of configuration

Racemate of (RS)-Bupropion (Bup) has been separated by derivatization approach and thin layer chromatography (TLC). It was extracted from commercially available tablets, purified, and characterized. A new chiral derivatization reagent (CDR) was synthesized by introducing L-leucine amide and butoxy group in cyanuric chloride (CC) moiety. Derivatization reaction was carried out using a two-fold molar excess of CDR under microwave irradiation (MWI). The diastereomeric pair was separated by TLC and the same were recovered by the preparative method; these were purified and characterized. Absolute configuration of the Bup moiety in the diastereomeric derivatives was confirmed by recording their ¹HNMR spectra and thus elution order was also established.     

Secretion of human interleukin-2 fused with green fluorescent protein in recombinatn <Emphasis Type="Italic">pichia pastoris</Emphasis>

Methylotrophic yeast Pichia pastoris is convenient for the expression of eukaryotic foreign proteins owing to its potential for posttranslational modifications, protein folding, and facile culturing. In this work, human interleukin (hIL)-2 was successfully produced as a secreted fusion form in recombinant P. pastoris. By employing green fluorescent protein (GFP) as a monitoring fusion partner, clear identification of fusion protein expression and quantification of intracellular hIL-2 were possible even though there was no correlation between culture supernatant fluorescence and secreted hIL-2 owing to high media interference. Importantly, by the addition of casamino acids in basal medium, we were able to enhance threefold amount of secreted hIL-2, which was present both as a fusion and as a clipped fragment.     

Evaluation of Hydride-Based Stationary Phases for LC-MS

Two hydride-based stationary phases (cholesterol and bidentate C18) are evaluated for use in chromatographic analyses with mass spectroscopic detection. The stability of the bonded moieties and the background signal in the effluent from these columns are investigated. Separations of steroids and catecholamines are used to characterize these separation materials. Peak symmetries and efficiencies can provide additional insights into the effectiveness of the two phases. In one case a small column configuration directly connected to the mass spectrometer inlet is also tested.     

Synthesis of Biologically Active Carvacrol Compounds using Different Solvents and Supports

Natural monoterpenoids have been documented for their acute toxicity and repellent, antifeedent, reproduction inhibitory, and insecticidal actions. The present work aims to derive a variety of ether and ester compounds using polymer‐supported reactions from the polymer‐supported carvacrol anion was reacted with alkyl halides and acid chlorides to afford carvacryl ethers and esters, respectively. Furthermore, a special study on the effect of different solvents and supports revealed that Amberlite IRA 400 (chloride form) was found to be the best polymer support and acetone among the solvents.     

Effect of plant extracts on book deteriorated fungal species

Abstract

The aim of the study was to evaluate the effect of leaf extracts of four plants against some isolated fungal species from deteriorated books. Aqueous, methanol and chloroform extracts of selected plant species were screened in vitro for their antifungal activity against some book deteriorating fungal species. Fifteen species belonging to 09 genera were isolated and identified from infested books in library. Aqueous and solvent extracts of leaves of Azadiracta indica, Callistemon citrinus, Eucalyptus lanceolatus and Pongamia pinnata were tested against some dominant fungal species viz. Chaetomium spiralis, Alternaria alternata, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus and Rhizopus stolonifer. Solvent extracts exhibited potent inhibitory activity than aqueous extracts. However, these plant extracts exhibited moderate activity against A. flavus, C. spiralis, R. stolonifer and A. alternata.     

Chronology and characteristics of groundwater along the United Arab Emirates-Oman arid region: a guide for regional sustainability

Journal of Radioanalytical and Nuclear Chemistry - Estimating groundwater recharge rate is essential for water sustainability of the arid region of the United Arab Emirates that receives most...     

Measurement of natural radioactivity concentrations and chemical composition of coal and its post-combustion residues in KSA

Journal of Radioanalytical and Nuclear Chemistry - The variable values of 226Ra, 228Ra and 40K were identified in coal and coal combustion residuals (CCR) samples to redistribute radionuclides...     

A Review on Obesity Management through Natural Compounds and a Green Nanomedicine-Based Approach

Obesity is a serious health complication in almost every corner of the world. Excessive weight gain results in the onset of several other health issues such as type II diabetes, cancer, respiratory diseases, musculoskeletal disorders (especially osteoarthritis), and cardiovascular diseases. As allopathic medications and derived pharmaceuticals are partially successful in overcoming this health complication, there is an incessant need to develop new alternative anti-obesity strategies with long term efficacy and less side effects. Plants harbor secondary metabolites such as phenolics, flavonoids, terpenoids and other specific compounds that have been shown to have effective anti-obesity properties. Nanoencapsulation of these secondary metabolites enhances the anti-obesity efficacy of these natural compounds due to their speculated property of target specificity and enhanced efficiency. These nanoencapsulated and naive secondary metabolites show anti-obesity properties mainly by inhibiting the lipid and carbohydrate metabolizing enzymes, suppression of adipogenesis and appetite, and enhancing energy metabolism. This review focuses on the plants and their secondary metabolites, along with their nanoencapsulation, that have anti-obesity effects, with their possible acting mechanisms, for better human health.