Multi-analyte HPLC–DAD Method for Concurrent Analysis of Six Antimicrobials and Three Proton Pump Inhibitors Frequently used in Management of Helicobacter pylori Infection: Application to Simulated Intestinal Fluid Samples

Chromatographia - The present work deals with the optimization, validation and application of a versatile HPLC–DAD method for concurrent estimation of nine antimicrobials and proton pump...     

Crystal and molecular structure of crenatine carbonate

The crystal and molecular structure of 1-ethyl-4-methoxy-9H-pyrido[3,4b]indole (crenatine) carbonate C₁₄H₁₄N₂O·H₂CO₃, (MS, m/z 226)M _R 288.3, a-carboline alkaloid, has been determined from X-ray diffraction data. The compound crystallizes in the space group Pbca with cell parameters:a=11.616(4),b=18.450(8),c=12.992(5)Å,V=2784(2)ų,Z=8,D _calc=1.375 g cm^–3, (MoK)=0.71069Å,(Mo K)=0.94 cm^–1,F(000)=1216,R/R _w =8.2/10.3% for 1099 reflections. The ring system of the-carboline nucleus is planar. The title compound shows a two center hydrogen bond between the indole N-H group and the oxygen atom of a carbonate group. The structure does not display hydrogen bonding between-carboline groups but rather a bonding network involving the carbonate group.     

Piperaceae alkaloids: Part IV. Structure and Synthesis of Cyclostachine A,Cyclostachine B and Cyclopiperstachine

Three new alkaloids designated as cyclostachine A (2), cyclostachine B (7) and cyclopiperstachine (10) have been isolated from Piper trichostachyon C. DC. Their structures have been derived on the basis of spectral and degradative studies and confirmed by synthesis. The ¹H- and ¹³C-NMR. spectra of these compounds are discussed.     

Revised structures of pipoxide and pipoxide chlorohydrin

The structures assigned earlier to pipoxide and pipoxide chlorohydrin have been revised on the basis of 360 MHz PMR spectral evidence and decoupling experiments.     

An approach to solutions of coupled semilinear partial differential equations with applications

In this work, an approach for finding the solution of coupled semi‐linear diffusion equations for initial value problems is presented. The formal exact solution is found and the Picard iteration is constructed. It is shown that the constructed sequence of solutions converges uniformly for some classes of initial value problems. The problem of dispersion of an oxygen demanding pollutant released into a uniform flow is studied. Copyright © 2000 John Wiley & Sons, Ltd.     

Synthesis,biological evaluation and molecular docking studies of 6-(4-nitrophenoxy)-1<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-b]pyridine derivatives as novel antitubercular agents: future DprE1 inhibitors

Tuberculosis is an air-borne disease, mostly affecting young adults in their productive years. Here, Ligand-based drug design approach yielded a series of 23 novel 6-(4-nitrophenoxy)-1H-imidazo[4,5-b]pyridine derivatives. The required building block of imidazopyridine was synthesized from commercially available 5,5-diaminopyridine-3-ol followed by four step sequence. Derivatives were prepared using various substituted aromatic aldehydes. All the synthesized analogues were characterized using NMR, Mass analysis and also screened for in vitro antitubercular activity against Mycobacterium tuberculosis (H₃₇Rv). Four compounds, 5c (MIC-0.6 μmol/L); 5g (MIC-0.5 μmol/L); 5i (MIC-0.8 μmol/L); and 5u (MIC-0.7 μmol/L) were identified as potent analogues. Drug receptor interactions were studied with the help of ligand docking using maestro molecular modeling interphase, Schrodinger. Here, computational studies showed promising interaction with other residues with good score, which is novel finding than previously reported. So, these compounds may exhibit in vivo DprE1 inhibitory activity.

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Dielectric spectroscopy in a micromachined flow cytometer: theoretical and practical considerations

We propose a model to determine the influence of different cell properties, such as size, membrane capacitance and cytoplasm conductivity, on the impedance spectrum as measured in a microfabricated cytometer. A dielectric sphere of equivalent complex permittivity is used as a simplified model to describe a biological cell. The measurement takes place between a pair of facing microelectrodes in a microchannel filled with a saline solution. The model incorporates various cell parameters, such as dielectric properties, size and position in the channel. A 3D finite element model is used to evaluate the magnitude of the electric field in the channel and the resultant changes in charge densities at the measurement electrode boundaries as a cell flows past. The charge density is integrated on the electrode surface to determine the displacement current and the channel impedance for the computed frequency range. The complete impedance model combines the finite element model, the electrode-electrolyte interface impedance and stray impedance, which are measured from a real device. The modeled dielectric complex spectra for various cell parameters are discussed and a measurement strategy for cell discrimination with such a system is proposed. We finally discuss the amount of noise and measurement fluctuations of the sensor.     

Degradation of a stilbene dye (SOTGL) in aqueous solutions under gamma-radiation

The effect of radiation on the colour intensity of aerated, oxygen and nitrogen-saturated aqueous solution of Solophenyl Orange TGL has been investigated. Experiments show that the absorption band decreases gradually with the increase of the dose in all cases and the destruction of the skeleton of the dye molecule is promoted, by the presence of oxygen. The kinetics of degradation of solution of (SOTGL) turned out to be of the first order with respect to the low dye concentration (<0.14 g/l) and of zero order for dye concentration (>0.14 g/l). The radiochemical degradation yield (Gd) was calculated and was found to decrease experimentally with the increase of dose for low concentrations, whereas for higher concentrations such a behaviour can be presented by a straight line parallel to the dose axis. The influence of pH on the degradation of the dye was studied. The specific bimolecular rate constant of the reaction of SOTGL with the hydroxyl radical was determined by studying the effect of ethanol concentration on Gd using competition kinetics and was found to be 1.055·10⁹ M^–1 s^–1. Suggestions are made for possible low radiation dosimetry (about 1.5 kGy) by means of spectrophotometric analysis of the absorption spectra.     

Numerical simulation of particulate-flow in spiral separators: Part I. Low solids concentration (0.3% & 3% solids)

The aim of the present study is the simulation of the particulate flow in spiral separators. The study is based on Eulerian approach and turbulence modeling. The results focus on particulate-flow characteristics such as the velocity, the distribution, and concentration of particulates on the spiral trough. The predicted results are compared with the experimental findings from LD9 coal spiral. The comparison shows good agreement and indicates that the most accurate turbulence model is RNG K–ε.