Thermoluminescence studies of UV-irradiated Y2O3:Eu3+ doped phosphor

The present paper reports thermoluminescence (TL) glow curves of Eu³⁺-doped Y₂O₃ phosphor with different ultraviolet (UV) exposure times. The glow peak shows second-order kinetics of Eu³⁺-doped Y₂O₃, and corresponding kinetic parameters were evaluated using the peak shape method. Calculations of trap depth were carried out using different methods. The kinetics order, activation energy, and frequency factor were calculated. The recorded glow curve shifts towards higher intensity with longer UV exposure. The heating rate used for recording TL was 3.0 °C s^?1. Particle size and structure were verified by X-ray diffraction (XRD) pattern and morphology by scanning electron microscopy (SEM) imaging.     

Spectrophotometric analysis of trichloroethylene in various environmental and biological samples

A simple sensitive extractive spectrophotometric method for determination of trichloroethylene is proposed. Trichloroethylene is treated with pyridine to form glutaconic aldehyde by heterolytic cleavage of the pyridine ring. Glutaconic aldehyde is further coupled with 4-aminoacetanilide to form an orange–red dye which is extractable in 3-methyl-1-butanol. The extracted dye shows absorption maximum at 520 nm. The system obeys Beer’s law in the range of 0.05–0.8 μg mL^?1. Important analytical parameters such as time, temperature, reagent concentration, acidity etc. have been optimized for complete colour reaction. Sandell’s sensitivity and molar absorptivity for the system were found to be 0.001 μg cm^?2 and 1.2 × 10⁵ L mol^?1 cm^?1, respectively. The proposed method is satisfactorily applied to micro-level determination of trichloroethylene in various environmental and biological samples.     

Investigation of the reaction mechanism and kinetics of production of anhydrous sodium metaborate (NaBO2) by a solid-state reaction

In this study, the solid-state reaction mechanism and kinetics were investigated for production of anhydrous sodium metaborate (NaBO₂), an industrially and technologically important boron compound. To assess the kinetics of solid-state production of NaBO₂, the chemical reaction between borax (Na₂B₄O₇) and sodium hydroxide (NaOH) was investigated by use of the thermal analysis techniques thermogravimetry (TG) and differential thermal analysis (DTA). DTA curves obtained under non-isothermal conditions at different heating rates (5, 10 and 20 °C/min), revealed five endothermic peaks corresponding to five solid-state reactions occurring at 70, 130, 295, 463, and 595 °C. The stages of the solid-state reaction used for production NaBO₂ were also analyzed by XRD, which showed that at 70 and 130 °C, Na₂B₄O₇ and NaOH particles contacted between the grains, and diffusion was initiated at the interface. However, there was not yet any observable formation of NaBO₂. Formation of NaBO₂ was initiated and sustained from 295 to 463 °C, and then completed at 595 °C; the product was anhydrous NaBO₂. Activation energies (E _a) of the solid-state reactions were calculated from the weight loss based on the Arrhenius model; it was found that in the initial stages of the solid-state reaction E _a values were lower than in the last three steps.     

Synthesis and biological evaluation of 5′-O-dicarboxylic fatty acyl monoester derivatives of anti-HIV nucleoside reverse transcriptase inhibitors

A number of 5′-O-dicarboxylic fatty acyl monoester derivatives of 3′-azido-3′-deoxythymidine (zidovudine, AZT), 2′,3′-didehydro-2′,3′-dideoxythymidine (stavudine, d4T), and 3′-fluoro-3′-deoxythymidine (alovudine, FLT) were synthesized to improve the lipophilicity and potentially the cellular delivery of parent polar 2′,3′-dideoxynucleoside (ddN) analogs. The compounds were evaluated for their anti-HIV activity. Three different fatty acids with varying chain length of suberic acid (octanedioic acid), sebacic acid (decanedioic acid), and dodecanedioic acid were used for the conjugation with the nucleosides. The compounds were evaluated for anti-HIV activity and cytotoxicity. All dicarboxylic ester conjugates of nucleosides exhibited significantly higher anti-HIV activity than that of the corresponding parent nucleoside analogs. Among all the tested conjugates, 5′-O-suberate derivative of AZT (EC₅₀ = 0.10 nM) was found to be the most potent compound and showed 80-fold higher anti-HIV activity than AZT without any significant toxicity (TC₅₀ >500 nM).     

Head group specificity of novel functionalized surfactants: synthesis,self-assembly and calcium tolerance

The present work describes the synthesis, characterization and application of functionalized surfactants derived through simple organic reaction steps. These surfactants have been particularly tailor made to resist hardness due to calcium ions in water. It is unique of its kind because here the surfactants have an analogous hydrophobic chain but differ structurally in the composition of the head groups in terms of the position of attachment of the chain. The effect of this small variability in the head group on the surfactant property, adsorption, self assembly and calcium tolerance behaviour has been studied in detail. This kind of phenol–keto surfactants has not been reported before. It was also found that one of the surfactants was more tolerant towards Ca²⁺ ion than the other. The individual packing behaviour of the surfactants at the air–water interface has been projected to cause this difference which is very interesting.     

An unusual conformation of gabapentin (Gpn) in Pyr‐Gpn‐NH‐NH‐Pyr stabilized by weak interactions

The crystal structure of N‐[(1‐{2‐oxo‐2‐[2‐(pyrazin‐2‐ylcarbonyl)hydrazin‐1‐yl]ethyl}cyclohexyl)methyl]pyrazine‐2‐carboxamide monohydrate (Pyr‐Gpn‐NN‐NH‐Pyr·H₂O), C₁₉H₂₃N₇O₃·H₂O, reveals an unusual trans–gauche (tg⁻) conformation for the gabapentin (Gpn) residue around the C^γ—C^β (θ₁) and C^β—C^α (θ₂) bonds. The molecular conformation is stabilized by intramolecular N—H...N hydrogen bonds and weak C—H...O interactions. The packing of the molecules in the crystal lattice shows a network of strong N—H...O and O—H...O hydrogen bonds together with weak C—H...O and π–π inteactions.     

Comparative evaluation of antibacterial potentials of nano cobalt oxide with standard antimicrobials

Development of suitable potent antimicrobial is the urgent need of modern era to cope up the problem of antimicrobial resistance. The applications of nanotechnology in metal oxides have shown favorable effects to some extent in this area. Thus, the present study was investigated to evaluate the antibacterial properties of cobalt oxide (Co₃O₄) nanoparticles at different concentrations and their comparison with standard antimicrobials i.e. tetracycline and gentamicin. Nanoparticles were synthesized and characterized by standard techniques. The antibacterial potentials of Co₃O₄ nanoparticles against S. aureus and E. coli were determined at various concentrations. The maximum zone of inhibitions of Co₃O₄ nanoparticles against S. aureus and E. coli at 500 μg/ml were 21.17 mm and 24.00 mm, respectively. The Co₃O₄ nanoparticles seemed more effective than gentamicin against S. aureus and E. coli. The nanoparticles with respect to tetracycline showed higher than 1 activity index at ≥ 125 μg/ml for E. coli and ≥31.25 μg/ml for S. aureus. It was also higher than 1 at all compared concentrations with respect to gentamicin against both bacteria. In conclusion, Co₃O₄ nanoparticles seemed to have potent antibacterial potential and these might be very helpful to replace the conventional antimicrobials to solve the problem of antibacterial resistance.     

Synthesis and computational studies of potent antimicrobial and anticancer indolone scaffolds with spiro cyclopropyl moiety as a novel design element

The indolones nucleus is the central core to develop new effective anticancer agents and its substitution at the 3-position can affect antitumor activity, 3-spirocyclopropyl-2-oxindoles have attracted the scientist's community to design and develop expedition's strategies towards their construction and explore the potential of this useful scaffold with their newer derivatives in medicinal world. The present paper describes the synthesis of 3-spirocyclopropyl-2-indolone derivatives in three steps via synthesis of ylide leading to methylene-indolinones followed by the formation of the final product spirocyclopropyl oxindole derivatives with improved yields. In this milieu we considered motivating to advance exploration the biological potencies and computational studies of our newly synthesized molecules. The aimed target molecules were screened for antimicrobial and anticancer activities where they exhibited substantial effective antimicrobial activities. Amongst them, potent compound, bromospirocyclopropyl indolone, 6d displayed encouraging MIC ranging from 0.007 to 0.49 μg/mL for gram positive microbes and also substantial anticancer activity with an IC₅₀ of 11.5 μg/mL. Finally, the computational modelling studies were performed to explore structure-activity relationship analysis. Active site of receptor protein shows docking scores of these molecules as - 5.78 kcal/mol and ?5.097 kcal/mol for the docked target proteins. The binding energy of the best score is found to be ?41.67 kcal/mol to ?44.67 kcal/mol. Thus, the present paper efficaciously validated spirocyclopropyl indolone framework for drug candidates as potent anticancer as well as antimicrobial compounds.     

Investigation of bio-corrosion in galvanized steel by Desulfovibrio desulfuricans and its mitigation by Butea monosperma leaf extract as green inhibitor

This work is intended to examine the microbially influenced corrosion on galvanized steel (GS) caused by sulfate-reducing bacteria (SRB). The efficacy of Butea monosperma (palash) leaf extract to mitigate the corrosion caused by Desulfovibrio desulfuricans was investigated in modified Barr's medium. Weight loss and electrochemical analysis were performed to check the corrosion rate at regular time intervals. SEM images were performed to understand the level of deterioration of the metal surfaces. Image analysis of the unprotected sample showed the presence of pits. From the gravimetric study, the maximum inhibition efficiency (IE) of 98% was obtained with 500 ppm of Palash leaf extract for the fourth-week sample. With the addition of 500 ppm of palash extract, the sulfide concentration decreases to 0 ppm from 123 ppm. Outcomes of potentiodynamic polarization (PP) studies showed that the extract disturbs the cathodic reaction significantly and moves the corrosion potential to a more negative value and IE was about 71% from PP studies. FTIR and GC-MS analysis was performed to recognize the plausible chemical compounds present in Palash leaf powder. EIS results confirmed that the resistance to corrosion increases substantially with the addition of inhibitor. The mechanism for corrosion inhibition has been proposed based on the results obtained.     

Electrocatalytic sensing of omeprazole

Ionics - A novel, simple, sensitive, and highly selective omeprazole sensor based on the synergistic effect of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) has been developed. The...