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21.
The present paper reports for the first time an exact analytic expression that can be used for obtaining fracture stress σF, when fracture occurs in the elastic limit and also when fracture occurs after general yield (σF > σY) in a brittle solid. The present paper may provide a new basis to fracture-safe design of brittle materials. 相似文献
22.
The present review deals with coherent states, its application to various problems in physics, chemistry and biology and its important applications to anharmonic, time-dependent and damped oscillator systems. It is seen that use of these states overcomes certain theoretical difficulties. 相似文献
23.
The percentage contribution of the peripheral phonons towards the total phonon conductivity of P-doped Ge has been studied with the help of the Ziman expression of the electron-phonon scattering relaxation rate and the Callaway integral of the lattice thermal conductivity. It is found that the percentage contribution of the peripheral phonons increases with the increase of temperature. The entire study is limited to the temperature range 1–5 K. 相似文献
24.
Prof. Vladimir I. Bregadze Prof. Igor B. Sivaev Ravindra Dhar Dubey Prof. Andrey Semioshkin Dr. Akim V. Shmal'ko Dr. Irina D. Kosenko Kseniya V. Lebedeva Prof. Swadhin Mandal Prasannakumar Sreejyothi Arindam Sarkar Prof. Zheyu Shen Prof. Aiguo Wu Prof. Narayan S. Hosmane 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(61):13832-13841
A series of boron-containing lipids were prepared by reactions of cyclic oxonium derivatives of polyhedron boranes and metallacarboranes (closo-dodecaborate anion, cobalt and iron bis(dicarbollides)) with amine and carboxylic acids which are derived from cholesterol. Stable liposomal formulations, on the basis of synthesized boron-containing lipids, hydrogenated soybean l -α-phosphatidylcholine and (HSPC) 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG) as excipients, were prepared and then characterized by dynamic light scattering (DLS) that revealed the formation of particles to be smaller than 200 nm in diameter. The resulting liposomal formulations showed moderate to excellent loading and entrapment efficiency, thus justifying the design of the compounds to fit in the lipid bilayer and ensuring ease of in vivo use for future application. The liposomal formulations based on cobalt and iron bis(dicarbollide)-based lipids were found to be nontoxic against both human breast normal epithelial cells MCF-10A and human breast cancer cells MCF-7. 相似文献
25.
Dr. Peng Wang Dr. Chang-xin Huo Shuyao Lang Dr. Kyle Caution Dr. Setare Tahmasebi Nick Prof. Purnima Dubey Prof. Rajendar Deora Prof. Xuefei Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6513-6520
With the infection rate of Bordetella pertussis at a 60-year high, there is an urgent need for new anti-pertussis vaccines. The lipopolysaccharide (LPS) of B. pertussis is an attractive antigen for vaccine development. With the presence of multiple rare sugars and unusual glycosyl linkages, the B. pertussis LPS is a highly challenging synthetic target. In this work, aided by molecular dynamics simulation and modeling, a pertussis-LPS-like pentasaccharide was chemically synthesized for the first time. The pentasaccharide was conjugated with a powerful carrier, bacteriophage Qβ, as a vaccine candidate. Immunization of mice with the conjugate induced robust anti-glycan IgG responses with IgG titers reaching several million enzyme-linked immunosorbent assay (ELISA) units. The antibodies generated were long lasting and boostable and could recognize multiple clinical strains of B. pertussis, highlighting the potential of Qβ-glycan as a new anti-pertussis vaccine. 相似文献
26.
A low dissipative framework is given to construct high order entropy stable flux by addition of suitable numerical diffusion operator into entropy conservative flux. The framework is robust in the sense that it allows the use of high order reconstructions which satisfy the sign property only across the discontinuities. The third order weighted essentially non-oscillatory (WENO) interpolations and high order total variation diminishing (TVD) reconstructions are shown to satisfy the sign property across discontinuities. Third order accurate entropy stable schemes are constructed by using third order WENO and high order TVD reconstructions procedures in the diffusion operator. These schemes are efficient and less diffusive since the diffusion is actuated only in the sign stability region of the used reconstruction which includes discontinuities. Numerical results with constructed schemes for various test problems are given which show the third order accuracy and less dissipative nature of the schemes. 相似文献
27.
Durgesh Dubey Smriti Chaurasia Anupam Guleria Sandeep Kumar Dinesh Raj Modi Ramnath Misra Dinesh Kumar 《Magnetic resonance in chemistry : MRC》2019,57(1):30-43
Currently, there are no reliable biomarkers available that can aid early differential diagnosis of reactive arthritis (ReA) from other inflammatory joint diseases. Metabolic profiling of synovial fluid (SF)—obtained from joints affected in ReA—holds great promise in this regard and will further aid monitoring treatment and improving our understanding about disease mechanism. As a first step in this direction, we report here the metabolite specific assignment of 1H and 13C resonances detected in the NMR spectra of SF samples extracted from human patients with established ReA. The metabolite characterization has been carried out on both normal and ultrafiltered (deproteinized) SF samples of eight ReA patients (n = 8) using high-resolution (800 MHz) 1H and 1H─13C NMR spectroscopy methods such as one-dimensional 1H CPMG and two-dimensional J-resolved1H NMR and homonuclear 1H─1H TOCSY and heteronuclear1H─13C HSQC correlation spectra. Compared with normal SF samples, several distinctive 1H NMR signals were identified and assigned to metabolites in the 1H NMR spectra of ultrafiltered SF samples. Overall, we assigned 53 metabolites in normal filtered SF and 64 metabolites in filtered pooled SF sample compared with nonfiltered SF samples for which only 48 metabolites (including lipid/membrane metabolites as well) have been identified. The established NMR characterization of SF metabolites will serve to guide future metabolomics studies aiming to identify/evaluate the SF-based metabolic biomarkers of diagnostic/prognostic potential or seeking biochemical insights into disease mechanisms in a clinical perspective. 相似文献
28.
Tak V Kanaujia PK Pardasani D Kumar R Srivastava RK Gupta AK Dubey DK 《Journal of chromatography. A》2007,1161(1-2):198-206
A qualitative method was developed for the determination of degraded products of nerve agents by using ion-pair liquid chromatography electrospray ionization tandem mass spectrometry (IP-LC-ESI-MS(n)). Generally, alkylphosphonic acids (APAs) and O-alkyl alkylphosphonic acids (AAPAs) give deprotonated molecular ion [M-H](-) in negative mode. Interestingly, first time we obtained the molecular radical anion [M](.-) of phosphonic acids in negative mode by using tri-n-butyl amine as an ion-pairing agent. We interpreted this observation as an indication of electrochemical reduction of phosphonic acids in electrospray needle. Three variables such as sheath gas flow, electrospray needle voltage and pH of the mobile phase were investigated to enhance the molecular radical anion [M](.-) signal of each analyte. The Doehlert design was used to obtain the region in which the optimum value of such variables is simultaneously achieved. Limit of detection achieved was 0.5 microg mL(-1) for AAPAs and 10 microg mL(-1) for APAs. Excellent precision was observed with less than 8.61% RSD. Finally, the method was applied for the detection of ethyl methylphosphonic in aqueous extract of soil sample. 相似文献
29.
Ankita RaiLal Dhar S. Yadav 《Tetrahedron letters》2011,52(30):3933-3936
The first one-pot three-component coupling reaction of O,O-diethyl hydrogen phosphorodithioate, aldehydes, and aldimines affording 1,2,4-trisubstituted 1,3-thiazetidines is reported. The product is obtained in moderate to high yields (45-94%) and has excellent diastereoselectivity (90-96%) in favour of the cis isomer. Shorter reaction times, ambient temperature, operational simplicity, and high yields are the salient features of the present procedure. 相似文献
30.
Debamitra Chakravorty Saravanan Parameswaran Vikash Kumar Dubey Sanjukta Patra 《Applied biochemistry and biotechnology》2012,167(3):439-461
Organic solvent-stable lipases have pronounced impact on industrial economy as they are involved in synthesis by esterification, interesterification, and transesterification. However, very few of such natural lipases have been isolated till date. A study of the recent past provided few pillars to rely on for this work. The three-dimensional structure, inclusive of the surface and active site, of 29 organic solvent-stable lipases was analyzed by subfamily classification and protein solvent molecular docking based on fast Fourier transform correlation approach. The observations revealed that organic solvent stability of lipases is their intrinsic property and unique with respect to each lipase. In this paper, factors like surface distribution of charged, hydrophobic, and neutral residues, interaction of solvents with catalytically immutable residues, and residues interacting with essential water molecules required for lipase activity, synergistically and by mutualism contribute to render a stable lipase organic solvent. The propensity of surface charge in relation to stability in organic solvents by establishing repulsive forces to exclude solvent molecules from interacting with the surface and prohibiting the same from gaining entry to the protein core, thus stabilizing the active conformation, is a new finding. It was also interesting to note that lipases having equivalent surface-exposed positive and negative residues were stable in a wide range of organic solvents, irrespective of their LogP values. 相似文献