Fluoranthene based fluorescent chemosensors for detection of explosive nitroaromatics

A novel fluoranthene based fluorescent chemosensor for the detection of picric acid (PA) at the parts per billion (ppb) level was evaluated. Static fluorescence quenching was the dominant process by intercalative π-π interaction between fluoranthene (S(1)) and nitroaromatics.     

Recoverable and thermally stable superhydrophobic silica coating

A facile route to methyltrimethoxysilane (MTMS) based recoverable superhydrophobic silica coatings with dual-scale roughness obtained through the single step base catalyst sol–gel process. Superhydrophobic silica coatings have shown static water contact angle near about 170 ± 1° and dynamic water contact angle up to 2 ± 1°. Superhydrophobic-superhydrophilic switching feature also achieved by alternating heat treatment and bath surface modification with Trimethylchlorosilane (TMCS) at room temperature (26 °C). Furthermore, the superhydrophobic state could be transformed into superhydrophilic state by slow rate heat treatment. These studies present a very simple strategy for the fabrication of recoverable superhydrophobic surfaces.     

Study of physical chemistry on biosorption of zinc by using Chlorella pyrenoidosa

Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. Presence of heavy metals in the aquatic system is posing serious problems. Zinc has been used in many industries and removal of Zn ions from waste water is significant. Biosorption is one of the economic methods used for removal of heavy metals. In the present study, the biomass obtained from the dried Chlorella pyrenoidosa was used for evaluating the biosorption characteristics of Zn ions in aqueous solutions. Batch adsorption experiments were performed with this material and it was found that the amount of metal ions adsorbed increased with the increase in the initial metal ion concentration. In this study effect of agitation time, initial metal ion concentration, temperature, pH and biomass dosage were studied. Maximum metal uptake (q _max) observed at pH 5 was 101.11 mg/g. The biosorption followed both Langmuir and Freundlich isotherm model. The adsorption equilibrium was reached in about 1 h. The kinetic of biosorption followed the second-border rate. The biomass could be regenerated using 0.1 M HNO₃. A positive value of ΔH° indicated the endothermic nature of the process. A negative value of the free energy (ΔG°) indicated the spontaneous nature of the adsorption process. A positive value of ΔS° showed increased randomness at solid-liquid interface during the adsorption of heavy metals, it also suggests some structural changes in the adsorbate and the adsorbent. FTIR Spectrums of Chlorella pyrenoidosa revealed the presence of hydroxyl, amino, carboxylic and carbonyl groups. The scanning electron micrograph clearly revealed the surface texture and morphology of the biosorbent.     

Microwave assisted mild, rapid, solvent-less, and catalyst-free chemoselective N-tert-butyloxycarbonylation of amines

Microwave assisted simple, rapid, solventless, and catalyst-free chemoselective method for the protection of amino group in aromatic, aliphatic, heterocyclic, aralkyl amines, phenyl hydrazine, and amino acid esters in good to excellent isolated yield (83-98%) in short reaction time (2-12 min) has been reported.     

Thin-film models of liquid displacement on chemically patterned surfaces for lithographic printing processes

We examine in this work a model problem relevant to the liquid displacement that occurs in lithographic printing processes. The model problem consists of two stratified thin liquid films confined between parallel plates, one of which is chemically heterogeneous. The films are assumed to be thin enough so that intermolecular forces are important and the lubrication approximation can be invoked. Both linear stability analysis and nonlinear simulations are applied to a partial differential equation governing the behavior of the liquid-liquid interface. The results provide physical insights into and numerical estimates of the smallest and largest feature sizes that can be printed, as well as the minimum spacing between feature sizes that can be tolerated. The results also provide insight into experimental observations on a closely related process, wire-wound rod coating on chemically patterned surfaces. The work presented here has important implications for the production of electronic devices and displays by lithographic printing, as well as for other processes that rely on coating and printing on chemically patterned surfaces.     

Validated LC–MS/MS method for quantification of agomelatine in human plasma and its application in a pharmacokinetic study

An analytical method based on liquid–liquid extraction has been developed and validated for analysis of agomelatine in human plasma. Fluoxetine was used as an internal standard for agomelatine. A Betasil C18 (4.0 × 100 mm, 5 µm) column provided chromatographic separation of analytes followed by detection with mass spectrometry. The method involves simple isocratic chromatographic conditions and mass spectrometric detection in the positive ionization mode using an API‐4000 system. The proposed method has been validated with linear range of 0.050–8.000 ng/ml for agomelatine. The intra‐run and inter‐run precision values are within 12.12% and 9.01%, respectively, for agomelatine at the lower limit of quantification level. The overall recovery for agomelatine and fluoxetine was 67.10% and 72.96%, respectively. This validated method was used successfully for analysis of plasma samples from a pharmacokinetic study. Copyright © 2012 John Wiley & Sons, Ltd.     

Unfairly forgotten member of the iodocarborane family: synthesis and structural characterization of 8-iodo-1,2-dicarba-closo-dodecaborane, its precursors, and derivatives

8-Iodo-1,2-dicarba-closo-dodecaborane (7) was prepared in three steps starting from decaborane-14 with 20% overall yield. In the presence of nucleophiles, compound 7 undergoes selective removal of the boron vertex in the position para to the iodine substituent to form the anionic nido-carborane 1-iodo-7,8-dicarba-nido-undecaborate. Capping of the corresponding dicarbollide dianion with BI(3) led to formation of the new carborane, 3,10-diiodo-1,2-dicarba-closo-dodecaborane (15). The same dicarbollide dianion reacts with cobalt and nickel acetylacetonates in anhydrous tetrahydrofuran to form the corresponding bis(dicarbollide) complexes with excellent yields. All compounds were characterized by multinuclear NMR and high-resolution mass spectroscopy. Structures of 2-iododecaborane (2), 8-iodo-1,2-dicarba-closo-dodecaborane (7), 1-ethoxycarbonyl-8-iodo-1,2-dicarba-closo-dodecaborane (10), cesium 1-iodo-7,8-dicarba-nido-undecaborate (13), 3,10-diiodo-1,2-dicarba-closo-dodecaborane (15), and cesium 3,3'-commo-(10-iodo-1,2-dicarba-3-cobalta-closo-dodecaborane)-(10'-iodo-1',2'-dicarba-3'-cobalta-closo-dodecaborane) (16) were established by X-ray analysis of single crystals.     

Biological and Cheminformatics Studies of Newly Designed Triazole Based Derivatives as Potent Inhibitors against Mushroom Tyrosinase

A series of nine novel 1,2,4-triazole based compounds were synthesized through a multistep reaction pathway and their structures were scrutinized by using spectral methods such as FTIR, LC-MS, 1H NMR, and 13C NMR. The synthesized derivatives were screened for inhibitory activity against the mushroom tyrosinase and we found that all the synthesized compounds demonstrated decent inhibitory activity against tyrosinase. However, among the series of compounds, N-(4-fluorophenyl)-2-(5-(2-fluorophenyl)-4-(4-fluorophenyl)-4H-1,2,4-triazol-3-ylthio) acetamide exhibited more prominent activity when accompanied with the standard drug kojic acid. Furthermore, the molecular docking studies identified the interaction profile of all synthesized derivatives at the active site of tyrosinase. Based on these results, N-(4-fluorophenyl)-2-(5-(2-fluorophenyl)-4-(4-fluorophenyl)-4H-1,2,4-triazol-3-ylthio) acetamide could be used as a novel scaffold to design some new drugs against melanogenesis.     

Forty years of the Staebler–Wronski effect

This article describes highlights of investigations of the Staebler–Wronski effect (SWE), observed in hydrogenated amorphous silicon since its discovery. Some of the basic characteristics of SWE are discussed along with some solved and unsolved puzzles. Particular emphasis is given to a recent model based on long-range potential fluctuations caused by heterogeneities present in the films. Evidence is reviewed for the presence of several kinds of dangling-bond defects produced by light exposure (hv?>?1.3?eV) at different temperatures between 4.2 and 360?K. With exposure at lower temperature the defects become less stable, but they possess larger recombination cross-sections. Voids in the material have been identified as the location for light-induced defects most harmful to the efficiency of solar cells. Ways to eliminate them are discussed. We suggest that progress in this field was delayed by lack of sample sharing among laboratories.