Boric acid as an efficient catalyst for the synthesis of 1,1-diacetate under solvent-free condition

Boric acid (BO₃H₃) is an inexpensive, efficient and mild catalyst for the synthesis of 1,1-diacetate (acylal) from the various aromatic and heteroaryl aldehydes with acetic anhydride at room temperature under solvent-free condition. The present method does not involve any hazardous organic solvents or catalysts. This method gives notable advantages such as excellent chemoselectivity, mild reaction condition, short reaction times and excellent yield.     

Parametric studies on hydrocarbon fireball using large eddy simulations

Occurrences of fireball close to plant buildings due to the release of flammable hydrocarbon fuel caused by the formation of fuel vapour cloud poses severe safety concerns. On the availability of potential ignition source, the induced fireball would cause the damage to the structures of nuclear power plant by direct contact, radiation and/or convection of hot combustion products through the opening of air intakes and ducts. In the present paper, the accidental/ experimental observations and theoretical studies of fireball are summarised. Computational fluid dynamics (CFD) analyses have been carried out to study the behaviour of fireball using OpenFOAM CFD software. The parametric studies are conducted by varying the mass of fuel, inlet velocity and inlet diameter. The new correlations for fireball diameter and duration have been proposed based on the parametric studies using CFD simulations. The fireball with a larger amount of fuel releases the heat slower and for a longer duration. The high heat released rate (HRR) is observed in case of a larger inlet diameter used for the same mass. The incident radiation from the fireball is calculated at different locations to assess thermal hazard. Analysis performed show that various parameters like fireball diameter, duration and the radiative flux falling at different locations can be predicted well using CFD code.     

Transform-Limited Pulses Are Not Optimal for Resonant Multiphoton Transitions

Maximizing nonlinear light-matter interactions is a primary motive for compressing laser pulses to achieve ultrashort transform limited pulses. Here we show how, by appropriately shaping the pulses, resonant multiphoton transitions can be enhanced significantly beyond the level achieved by maximizing the pulse's peak intensity. We demonstrate the counterintuitive nature of this effect with an experiment in a resonant two-photon absorption, in which, by selectively removing certain spectral bands, the peak intensity of the pulse is reduced by a factor of 40, yet the absorption rate is doubled. Furthermore, by suitably designing the spectral phase of the pulse, we increase the absorption rate by a factor of 7.     

Scaffold hopping for identification of novel D2 antagonist based on 3D pharmacophore modelling of illoperidone analogs

The dopamine D(2) receptor is involved in the etiology of a number of disorders, such as Parkinson's disease, Huntington's Chorea, tardive dyskinesia and schizophrenia. Antagonism of D(2) receptors is implicated in the treatment of various psychiatric disorders. In order to understand essential structural features required for D(2) antagonism, this research article elaborates on the generation of a four-point 3D pharmacophore model which was extracted from a series of 45 novel 3-[[(aryloxy)alkyl]piperidinyl]-1,2-benzisoxazole derivatives. The best pharmacophore model generated consisted of four PRRR features: a positively charged group (P), and three aromatic rings (R). Based on the model generated, a statistically valid 3D-QSAR with good predictability (Q(2) = 0.756) was derived. For the validation of the pharmacophore hypothesis, active compounds were docked against the 3D structure of the D(2) receptor which was constructed through homology modeling. Further, the derived pharmacophore was used as a query to search the Zinc 'clean drug-like' database. Hits retrieved were passed progressively through filters, such as fitness score, predicted activity and docking scores. The resulting hits present new scaffolds with a strong potential for D(2) antagonist.     

Synthesis,spectroscopic characterization and thermal studies of some rare earth metal complexes of unsymmetrical tetradentate Schiff base ligand

The solid complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III) and Gd(III) with 4-hydroxy-3-(1-{2-(2-hydroxy-benzylidene)-aminophenylimino}-thyl)-6-methy-pyran-2-one (H₂L) derived from o-phenylenediamine, 3-acetyl-6-methyl-(2H)pyran,2,4(3H)-dione (dehydroacetic acid or DHA) and salicylic aldehyde have been synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV–visible, FTIR, ¹H NMR spectra, X-ray diffraction, and thermal analysis and screened for antimicrobial activity. The FTIR spectral data suggest that the ligand behaves as a dibasic tetradentate ligand with ONNO donar atoms sequence towards central metal ion. From the microanalytical data, the stoichiometry of the complexes has been found to be 1:1 (metal:ligand). The physico-chemical data suggest distorted octahedral geometry for La(III), Ce(III), Pr(III), Nd(III), Sm(III) and Gd(III) complexes. The X-ray diffraction data suggest monoclinic crystal system for La(III) and Ce(III) and orthorhombic crystal system for Pr(III) and Nd(III) complexes. Thermal behaviour (TGA/DTA) of the complexes was studied and kinetic parameters were determined by Horowitz–Metzger and Coats–Redfern methods. The ligand and their metal complexes were screened for antibacterial activity against Staphylococcus aureus, Escherichia coli and Bacillus sp. Fungicidal activity against Aspergillus niger, Trichoderma and Fusarium oxysporum.     

Ionic liquid promoted synthesis of bis(indolyl) methanes

1-benzyl-3-methyl imidazolium hydrogen sulphate [bnmim][HSO₄] was found to be an effective catalyst for the condensation reaction of indoles and derivatives with benzaldehydes in microwave irradiation with lower reaction time and higher yields to give bis(indolyl) methanes.      

Original GC–FID Determination of Non-Chromophoric Impurities in Quetiapine: An Antipsychotic Drug

A rapid and sensitive gas chromatographic method using flame ionization detection (GC–FID) has been developed and validated for five process related non-chromophoric impurities viz, 2-(2-chloroethoxy)ethanol (2-CEE), piperazine, 2-(piperazin-1-yl)ethanol (HEP), 2-[2-(piperazin-1-yl)ethoxy]ethanol (HEEP), 2,2-[piperazine-1,4-diylbis(ethane-2,1-diyloxy)]diethanol (DEEP) observed during the process development of quetiapine hemifumarate, an antipsychotic drug is presented. All five non-chromophoric impurities ranging from 0.05 to 0.1% were detected using DB-5 (30 m × 0.53 mm, 5 μm) column with a good peak separation. The method was fully validated according to the ICH Q2 (R1) guidelines. The investigated validation protocols showed that the method has acceptable specificity, accuracy, linearity, precision, robustness and high sensitivity with detection limits and quantitation limits ranging from 0.001 to 0.01% and 0.004 to 0.03%, respectively. These non-chromophoric impurities generated during the process were identified by GC–MS and are characterized by MS, ¹H NMR and FT-IR spectroscopy.

     

Exploration of biomass waste as low cost adsorbents for removal of methylene blue dye: A review

Biomass waste, which is abundantly available has been studied as low cost biosorbent for dye sequestration from waste water. The present review reports on recent development for remediation of methylene blue dye by agricultural waste and fruit peel waste material. The aim of this study was to revise latest literature in the field of dye adsorption and discuss the dye adsorption capacity of different types of adsorbents. The activated carbon prepared from several types of biomass waste material enhances the adsorption efficiency after modification. The variety of activating agents, method of activation, characterization of biosorbent material like SEM, EDAX, BET surface area and FTIR analysis has been explored in the present review. The dye adsorption factors such as effect of pH, agitation time, temperature, adsorbate and adsorbent dose were discussed. The detailed investigation on applicability of isotherm model, kinetic model and thermodynamic parameters has also been presented. The adsorption kinetics and adsorption isotherm model focus on selectivity of adsorbent. Adsorption mechanism, Influence of surface area, influence of pH_pzc and comparative study of biomass waste adsorbent with other adsorbents have been carried out. The use of biomass waste adsorbents is economically feasible, environmental healthy and found to have outstanding removal capacity of dyes.     

Nitrogen content determinations in different stages of thermal treatment involved in conversion of ammonium diuranate to uranium metal

Accurate, low-level measurement of ²²⁶Ra in high volume water samples requires rapid pre-concentration and robust separation techniques prior to measurement in order to comply with discharge limits and drinking water regulations. This study characterises the behaviour of ²²⁶Ra and interfering elements on recently developed TK100 (Triskem International) extraction chromatography resin. Distribution coefficients over a range of acid concentrations are given, along with an optimised procedure that shows rapid pre-concentration and separation of ²²⁶Ra on TK100 resin is achievable for high volume (1 L) water samples without the need for sample pre-treatment.