Propagation of Gaussian beams through parabolic index optical waveguides with random dielectric constant gradient

The propagation of gaussian beams through parabolic index optical waveguides having random irregularities in the dielectric constant gradient has been studied. For fundamental mode propagation, the perturbation approach has been employed and an analytic expression for the loss of power from the fundamental mode has been obtained. For an incident gaussian beam with arbitrary width, geometrical optics approximation has been used and an exact analytical expression for the average value of the beamwidth has been derived for a particular random process, namely, the dichotomic Markov process. The fluctuations in the beamwidth have also been calculated.     

Standardization and validation of phytometabolites by UHPLC and high-performance thin layer chromatography for rapid quality assessment of ancient ayurvedic medicine,Mahayograj Guggul

Mahayograj Guggul is an ancient ayurvedic medicine, prescribed for various joint disorders like arthritis, gout, and rheumatism. The present research was envisaged to develop a simple, sensitive, and comprehensive analytical method for standardization of Mahayograj Guggul. The analysis was conducted for gallic acid, protocatechuic acid, vanillic acid, cinnamic acid, piperine, guggulsterone-E, and guggulsterone-Z by high-performance thin-layer chromatography, and additionally ferulic acid, ellagic acid, and picroside I by ultra high-performance liquid chromatography. These developed methods were validated as per international guidelines, and were found linear (r² > 0.99), sensitive, precise (relative standard deviation < 5%), and accurate with recovery values (85–105%). The limit of detection and quantification were in the range of 0.11–23.6 and 0.33–71.51 μg/g. Gas chromatography tandem mass spectrometry was used to develop Mahayograj Guggul fingerprinting profile and to identify mid-polar or nonpolar compounds. Proximate analysis was used to ascertain the functional groups present in Mahayograj Guggul. Ultra high-performance liquid chromatography and gas chromatography tandem mass spectrometry were further employed to authenticate quality reproducibility in the active ingredients of Mahayograj Guggul in six commercial batches. Taken together, these analytical methods provide a scientific basis and reference for quality control evaluation of Mahayograj Guggul and similar traditional broad-spectrum formulations.     

A simple,rapid, and robust “on-the-go” identity testing of biotherapeutics using FTIR spectroscopy

The stunning rise of biotherapeutics as successful treatments of complex and hard-to-treat diseases, in particular cancer, has necessitated the development of a rapid analytical method capable of differentiating these otherwise significantly similar antibody-based products. The existing methods for product identification pose significant drawbacks in terms of the consumption of time and labor. Here, we present an FTIR spectroscopy-based simple, rapid, and robust method that is capable of differentiating between the biotherapeutics (both innovator products and biosimilars). The proposed approach uses partial least-squares-discriminant analysis to pinpoint subtle differences in the FTIR spectra of the samples, enabling us to not only identify the product but also calculate its concentration. This FTIR-based method can be used to fulfill the identity testing requirement of a pharmaceutical drug in its final packaged form set by the US Food and Drug Administration. Along with this, identity testing can also be deployed at multiple steps in the manufacturing process and can also be used by the appropriate regulatory or government agency for tackling counterfeits of biotherapeutic products.     

Raman signatures of strong and weak hydrogen bonds in binary mixtures of phenol with acetonitrile,benzene and orthodichlorobenzene

The present study aims at investigating the effect of hydrogen bonds of phenol in binary mixtures of phenol with three solvents viz. acetonitrile, orthodichlorobenzene and benzene respectively in order of decreasing hydrogen bond strength. Raman spectroscopy in correlation with density functional theory (DFT) calculations has led to a profound understanding of changes in structure, energy, dipole moment and other physical and chemical properties of phenol pertaining to hydrogen bond formation in solution. The spectral variation in wavenumber and linewidth of ring deformation, ring stretching, C≡N stretching and C―H stretching modes have been analyzed in detail. The breaking of self association of phenol in solution and formation of strong or weak hydrogen bonds depending on the nature of the solvent has been discussed by comparing the Raman and DFT results for three different solvents. Copyright © 2016 John Wiley & Sons, Ltd.     

Intersection multiplicities over Gorenstein rings

Let R be a complete local ring of dimension d over a perfect field of prime characteristic p, and let M be an R-module of finite length and finite projective dimension. S. Dutta showed that the equality holds when the ring R is a complete intersection or a Gorenstein ring of dimension at most 3. We construct a module over a Gorenstein ring R of dimension five for which this equality fails to hold. This then provides an example of a nonzero Todd class , and of a bounded free complex whose local Chern character does not vanish on this class. Received: February 11, 1999     

Multi-symbolic Rees algebras and strong F-regularity

Let I be a divisorial ideal of a strongly F-regular ring A. K.-i. Watanabe raised the question whether the symbolic Rees algebra is Cohen-Macaulay whenever it is Noetherian. We develop the notion of multi-symbolic Rees algebras and use this to show that is indeed Cohen-Macaulay whenever a certain auxiliary ring is finitely generated over A. Received August 10, 1998 / in final form October 18, 1999 / Published online July 20, 2000     

Biocomputational Assessment of Natural Compounds as a Potent Inhibitor to Quorum Sensors in Ralstonia solanacearum

Ralstonia solanacearum is among the most damaging bacterial phytopathogens with a wide number of hosts and a broad geographic distribution worldwide. The pathway of phenotype conversion (Phc) is operated by quorum-sensing signals and modulated through the (R)-methyl 3-hydroxypalmitate (3-OH PAME) in R. solanacearum. However, the molecular structures of the Phc pathway components are not yet established, and the structural consequences of 3-OH PAME on quorum sensing are not well studied. In this study, 3D structures of quorum-sensing proteins of the Phc pathway (PhcA and PhcR) were computationally modeled, followed by the virtual screening of the natural compounds library against the predicted active site residues of PhcA and PhcR proteins that could be employed in limiting signaling through 3-OH PAME. Two of the best scoring common ligands ZINC000014762512 and ZINC000011865192 for PhcA and PhcR were further analyzed utilizing orbital energies such as HOMO and LUMO, followed by molecular dynamics simulations of the complexes for 100 ns to determine the ligands binding stability. The findings indicate that ZINC000014762512 and ZINC000011865192 may be capable of inhibiting both PhcA and PhcR. We believe that, after further validation, these compounds may have the potential to disrupt bacterial quorum sensing and thus control this devastating phytopathogenic bacterial pathogen.     

Photoredox-Mediated Hydrogen Isotope Exchange Reactions of Amino-Acids,Peptides, and Peptide-Derived Drugs

Hydrogen isotopically labelled compounds are essential diagnostic tools in drug research and development, as they provide vital information about the biological metabolism of drug candidates and their metabolites. Herein we report a photoredox-initiated hydrogen atom transfer (HAT) protocol which efficiently and selectively introduces deuterium or tritium at C(sp³)−H bonds, utilizing heavy water (D₂O or T₂O) as the hydrogen isotope source, and a guanidine base. This protocol has been successfully applied to the incorporation of deuterium in several amino acids (lysine, glycine and proline) and small peptides. Finally, the method has been applied to tritium, because tritium-labelled peptides are essential for application in biological experiments, such as ligand-binding assays, or absorption, distribution, metabolism, and excretion (ADME) studies.