Chemical composition and antimicrobial activity of essential oil of Heracleum rigens

The essential oil was extracted from the seeds of Heracleum rigens by hydrodistillation and a total of twenty compounds accounting for 98.5% of the total oil composition were identified. Physicochemical properties and chemical composition of the oil was determined by a combination GC/FID and GC/MS analysis. The major compounds identified were bornyl acetate (51.2%), alpha-pinene (22.6%), limonene (9.62%), octyl acetate (3.94%), rho-cymene (2.85%) and gamma-terpinene (1.93%). The antimicrobial activity of the oil was screened by the disc diffusion method against nine pathogenic bacterial strains. Maximum antimicrobial activity was noted against Klebsiella pneumonia and Bacillus subtillis. This investigation corroborates the traditional claim of H. rigens as an effective antimicrobial agent.     

Synthesis of zeolite ZSM‐5: Effect of emulsifiers

Zeolite ZSM‐5 has been synthesized in presence of various emulsifiers. Influence of types and proportions of cationic, anionic and non‐ionic emulsifier has been studied. Cationic emulsifier, cetyl trimethyl ammonium bromide resulted in an amorphous phase, whereas anionic emuisifier, sodium lauryl sulphate afforded crystalline phase, identified as magadiite. Non‐ionic emulsifiers, 1,2,3‐benzotriazole and sorbital mono‐stearate led to the formation of pure crystalline ZSM‐5 phase. Emulsifier concentration was found to affect the process of crystallization, and the crystal size and morphology of ZSM‐5. Emulsifier necessitated higher crystallization temperature and/or longer hydrothermal period. ZSM‐5 crystallization was observed to proceed through magadiite phase formation. In case of benzotriazole, unusual stacked square platelet type morphology and with sorbital monostearate, very small crystals were observed.     

Effect of secondary structure on the self-assembly of amphiphilic molecules: a multiscale simulation study

The self-assembly of amphiphilic molecules is of interest from a fundamental and practical standpoint. There has been recent interest in a class of molecules made from β-amino acids (which contain an additional backbone carbon atom when compared with natural amino acids). Block copolymers of β-peptides, where one block is hydrophobic and the other is hydrophilic, self-assemble into micelles. In this work, we use computer simulations to provide insight into the effect of secondary structure on the self-assembly of these molecules. Atomistic simulations for the free energy of association of a pair of molecules show that a homochiral hydrophobic block promotes self assembly compared to a heterochiral hydrophobic block, consistent with experiment. Simulations of a coarse-grained model show that these molecules spontaneously form spherical micelles.     

Classical mechanics of directly interacting relativistic particles

We discuss the classical mechanics of relativistic systems containing any number of particles with direct interaction. We continue our previous approach of restricting the observables to gauge invariant variables. As a preliminary we show how to constructN-particle mass shell constraints. Physical momentum and position variables are constructed in consonance with nonsuperluminality and relativity and consistent with a slightly weakened separability which allows the position four vector of separated particles to differ from the canonical coordinate four vector by a constant term which depends on its history but does not affect future dynamics. The formalism is mathematically consistent though slightly more complicated than previous attempts in this direction.     

Quantitative determination of ragaglitazar in rat plasma by HPLC: validation and application in pharmacokinetic study

A specific, accurate, precise and reproducible high-performance liquid chromatography (HPLC) method was developed for the estimation of ragaglitazar [(-) DRF 2725, NNC 61-0029], a novel anti-diabetic agent, in rat plasma. The assay procedure involved simple liquid/liquid extraction of ragaglitazar and internal standard (IS, troglitazone) from plasma into ethyl acetate. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40 degrees C. The residue was reconstituted in the mobile phase and injected onto a Kromasil KR 100 - 5C(18) column (4.6 x 250 mm, 5 micro m). Mobile phase consisting of 0.01 M potassium dihydorgen ortho phosphate (pH 3.2) and acetonitrile (30:70, v/v) was used at a flow rate of 1.0 mL/min. The eluate was monitored using an UV detector set at 240 nm. Ratio of peak area of analyte to IS was used for quantification of plasma samples. Nominal retention times of IS and ragaglitazar were 6.9 and 12.2 min, respectively. The standard curve for ragaglitazar was linear (r(2) > 0.999) in the concentration range 0.2-100 micro g/mL. Absolute recovery was >87% from rat plasma for both analyte and IS. The lower limit of quantification (LLOQ) of ragaglitazar was 0.2 micro g/mL. The inter- and intra-day precision in the measurement of quality control (QC) samples, 0.2, 1.0, 5.0 and 50 micro g/mL, were in the range 1.32-3.70% relative standard deviation (RSD) and 1.19-9.39% RSD, respectively. Accuracy in the measurement of QC samples was in the range 94.28-107.45%. Analyte and IS were stable in the battery of stability studies, viz. benchtop, autosampler and freeze/thaw cycles. Stability of ragaglitazar was established for 1 month at -20 degrees C. The application of the assay to a pharmacokinetic study in rats is described.     

On Spin Distributions for Generic p-Spin Models

Journal of Statistical Physics - We provide an alternative formula for spin distributions of generic p-spin glass models. As a main application of this expression, we write spin statistics as...     

Physical nature of the event horizon

It is shown by arguments based on the uncertainty principle that large fluctuations of the metric occur near the event horizon of a Schwarzschild black hole on a scale much larger than Planck length. The width of the transition layer about the event horizon and the associated surface tension are also estimated.     

Post-Synthetic Modification of Zr-based Metal-Organic Frameworks with Imidazole: Variable Optical Behavior and Sensing

UiO-66-NH₂-IM, a fluorescent metal-organic framework (MOF), was synthesized by post-synthetic modification of UiO-66-NH₂ with 2-imidazole carboxaldehyde via a Schiff base reaction. It was examined using various characterization techniques (PXRD, FTIR, NMR, SEM, TGA, UV-Vis DRS, and photoluminescence spectroscopy). The emissive feature of UiO-66-NH₂-IM was utilized to detect volatile organic compounds (VOCs), metal ions, and anions, such as acetone, Fe³⁺, and carbonate (CO₃²⁻). Acetone turns off the high luminescence of UiO-66-NH₂-IM in DMSO, with the limit of detection (LOD) being 3.6 ppm. Similarly, Fe³⁺ in an aqueous medium is detected at LOD=0.67 μM (0.04 ppm) via quenching. On the contrary, CO₃²⁻ in an aqueous medium significantly enhances the luminescence of UiO-66-NH₂-IM, which is detected with extremely high sensitivity (LOD=1.16 μM, i. e., 0.07 ppm). Large Stern-Volmer constant, K_sv, and low LOD values indicate excellent sensitivity of the post-synthetic MOF. Experimental data supported by density functional theory (DFT) calculations discern photo-induced electron transfer (PET), resonance energy transfer (RET), inner filter effect (IFE), or proton abstraction as putative sensing mechanisms. NMR and computational studies propose a proton abstraction mechanism for luminescence enhancement with CO₃²⁻. Moreover, the optical behavior of the post-synthetic material toward analytes is recyclable.