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1

Recent advancement in metal containing multicomponent chalcogenide glasses

100%

Singh A. K.

Opto-Electronics Review

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2012

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tom Vol. 20, No. 3

226-238

EN

Amorphous semiconductors or chalcogenide glasses are the key materials in modern optoelectronics to make comfortable life of our society. Understanding of physical properties (like microstructure, thermal, optical, electrical) of these materials is important for their different uses. Predominant study of physical properties of the metal containing multicomponent chalcogenide glasses have attracted much attention, due to their interesting variable features and wide range of structural network modifications. Structural modifications in these materials are usually described with respect to the values of structural units (or average coordination number). In significance to this, the present work demonstrates the chronological development in the field of chalcogenide glasses along with scanning electron microscopy (SEM) morphologies. Optical, electrical and thermal correlative properties of recent developed Se93-xZn2Te5Inx (0 ≤ x ≤ 10) metallic multicomponent chalcogenide glasses are discussed. Variation in SEM morphology, refractive index (n), extinction coefficient (K), optical energy band gap (Eg), electrical conductivity (δav), crystallization activation energy (Ec) and glass forming ability (GFA) with structural units of Se-Zn-Te-In glasses have been demonstrated in this study. Subjected materials thermal, optical and electrical parameters have been achieved higher and lower in a respective manner at the threshold structural unit value (r)

2

Magnetogasdynamic shock waves in a non-uniform gas with heat conduction and radiation heat-flux

63%

Vishwakarama J. P. , Singh A. K.

International Journal of Applied Mechanics and Engineering

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2008

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tom Vol. 13, no 3

797-815

EN

The propagation of a cylindrical or spherical shock wave in an ideal gas with heat conduction and radiation heat-flux, in the presence of a spacially decreasing azimuthal magnetic field, is investigated. The initial density of the gas is assumed to obey a power law. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient are assumed to vary with temperature and density. The shock wave is assumed to be driven by a piston moving with a variable velocity. Similarity solutions are obtained and the effects of variation of the heat transfer parameters and the variation of piston velocity (or initial density) and Alfven-Mach number are investigated.

3

Transient natural convection between two vertical walls heated/cooled asymmetrically

63%

Singh A. K. , Paul T.

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tom Vol. 11, no 1

143-154

EN

The present paper analyses a closed form solution for the transient free convective flow of a viscous and incompressible fluid between two vertical walls as a result of asymmetric heating or cooling of the walls. The convection currents between the walls occur due to a change in the temperature of the walls to that of the temperature of the fluid. The Laplace transform method has been used to find the solutions for the velocity and temperature fields by solving the governing partial differential equations. The numerical values obtained from the analytical solution show that the flow is initially in the downward direction near the cooled wall for negative values of the buoyancy force distribution parameter. The temperature field of both the air and water gradually decreases and becomes negative near the cooled wall for all negative values of the buoyancy force distribution parameter. The transient solution approaches a steady state when the non-dimensional time becomes comparable with the actual Prandtl number.

4

Effect of elevated temperature on the accumulation of thylakoid proteins and plastid gene expression during light induced chloroplast development

63%

Singh A. K. , Singhal G. S.

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tom 34

5

Synergistic effect of salicylic acid and chitosan on postharvest life and quality attributes of jamun (Syzygium cumini Skeels) fruit

51%

Saurabh V. , Barman K. , Singh A. K.

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2019

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tom 41

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nr 06

EN

Syzygium cumini Skeels, commonly known as jamun, is an under-utilized fruit crop, native to India. The fruit is rich in several bioactive compounds and possesses several medicinal properties, especially therapeutic effects towards healing diabetes. However, the fruit deteriorates rapidly after harvest and can only be stored for 2–3 days at ambient conditions. Therefore, the present study was conducted to extend the storability and preserve jamun fruit quality during storage at ambient conditions. Fully ripe jamun fruits were immersed in salicylic acid (SA, 1.0 mM or 1.5 mM) or chitosan (1.5% w/v) solutions either alone or in combination. Fruits dipped in distilled water served as control. Following treatments, fruits were dried in air and stored at room temperature in corrugated fibre board boxes. The results indicated that 1.5% chitosan + 1.5 mM SA treatment was highly effective in preserving fruit quality and delaying senescence. This treatment resulted in about 19.5% lower weight loss, 49.9% lower decay loss, and 48% lower malondialdehyde content than control fruit. Combined treatment of chitosan and SA (1.5 mM) retained about 1.34-fold higher total anthocyanins, 1.69-fold higher total phenolics, 1.5-fold higher total flavonoids, 1.75-fold higher total antioxidant capacity, and 1.5-fold higher radical scavenging activity than control up to 6 day storage. Significant variations in ascorbic acid and titratable acidity were not recorded among salicylic acid-treated and chitosan-coated fruits; however, total soluble solids content was highest in chitosan-coated fruits. The findings of the study will be useful to increase the availability of jamun fruit and enable for its long-distance transport and subsequent marketing.

6

Nitric oxide application for postharvest quality retention of guava fruits

51%

Sahu S. K. , Barman K. , Singh A. K.

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tom 42

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nr 10

7

Effect of Corrugation and Reinforcement on the Dispersion of SH-wave Propagation in Corrugated Poroelastic Layer Lying over a Fibre-reinforced Half-space

51%

Singh A. K. , Das A. , Lakshman A. , Chattopadhyay A.

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2016

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tom Vol. 64, no. 5

1340--1369

EN

The presence of porosity and reinforcement in a medium is an important factor affecting seismic wave propagation and plays vital role in many geophysical prospects. Also, the presence of salt and ore deposits, mountains, basins, mountain roots, etc. is responsible for the existence of corrugated boundary surfaces of constituent layers. Such facts brought motivation for the present paper which deals with the propagation of SHwave in a heterogeneous fluid-saturated poroelastic layer with corrugated boundaries lying over an initially stressed fibre-reinforced elastic halfspace. Closed form of dispersion relation has been obtained and is found in well agreement to classical Love wave equation for isotropic case. The effect of corrugation, wave number, undulation, position parameter, horizontal compressive/tensile initial stress and heterogeneity on phase velocity has been analysed through numerical computation and graphical illustration. Moreover, comparative study exploring the effect of presence and absence of reinforcement in half-space on dispersion curve is the major highlight of the current study.

8

Assessment of low-cost intervention (foamrubber) among wood carvers exposed to hand-arm vibration and noise

51%

Singh A. K. , Meena M. L. , Chaudhary H. , Karmakar S.

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nr 203

9

Transient free-convective flow in a vertical channel due to symmetric heating

51%

Jha B. K. , Singh A. K. , Takhar H. S.

International Journal of Applied Mechanics and Engineering

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2003

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tom Vol. 8, no 3

497-502

EN

This paper presents a closed form solution for a transient free convective flow of a viscous and incompressible fluid in a vertical channel due to symmetric heating of channel walls. The Laplace transform technique has been used to obtain the expression for the velocity and temperature fields by solving the governing differential equations. The influence of the physical parameters on the velocity field, skin-friction, rate of heat transfer and volumetric flux of the fluid are carefully analysed. A correlation between the steady state time and the Prandtl number has been developed. It is observed that the nature of correlation is linear when the Prandtl number is greater than one while cubic for the Prandtl number is less than one.

10

Impact of Inhomogeneity on SH-type Wave Propagation in an Initially Stressed Composite Structure

51%

Saha S. , Chattopadhyay A. , Singh A. K.

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tom Vol. 66, no. 1

1--19

EN

The present analysis has been made on the influence of distinct form of inhomogeneity in a composite structure comprised of double superficial layers lying over a half-space, on the phase velocity of SH-type wave propagating through it. Propagation of SH-type wave in the said structure has been examined in four distinct cases of inhomogeneity viz. when inhomogeneity in double superficial layer is due to exponential variation in density only (Case I); when inhomogeneity in double superficial layers is due to exponential variation in rigidity only (Case II); when inhomogeneity in double superficial layer is due to exponential variation in rigidity, density and initial stress (Case III) and when inhomogeneity in double superficial layer is due to linear variation in rigidity, density and initial stress (Case IV). Closed-form expression of dispersion relation has been accomplished for all four aforementioned cases through extensive application of Debye asymptotic analysis. Deduced dispersion relations for all the cases are found in well-agreement to the classical Love-wave equation. Numerical computation has been carried out to graphically demonstrate the effect of inhomogeneity parameters, initial stress parameters as well as width ratio associated with double superficial layers in the composite structure for each of the four aforesaid cases on dispersion curve. Meticulous examination of distinct cases of inhomogeneity and initial stress in context of considered problem has been carried out with detailed analysis in a comparative approach.

11

Natural convection in a hydrodynamically and thermally anisotropic non-rectangular porous cavity: effect of internal heat generation/absorption

51%

Chandran P. , Sacheti N. C. , Bhadauria B. S. , Singh A. K.

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tom Vol. 23, no. 3

595--609

EN

Laminar natural convection in a trapezoidal porous vertical cavity has been investigated in this work. It is assumed that the porous enclosure is filled up with a permeable material subject to hydrodynamic and thermal anisotropy, the flow being governed by the Darcy law as applicable to a non-isotropic medium. It is further assumed that (i) there is heating at the left vertical wall and cooling at the right wall of the enclosure and (ii) the flow domain is subject to the presence of heat source or heat sink. The partial differential equations governing the resulting free convection have been solved numerically in the non-dimensional forms. There arises a number of parameters relating to buoyancy, internal heating, cavity aspect ratio and inclination of the upper surface to the horizontal. The influence of these parameters has been illustrated and analyzed through contours of streamlines and isotherms. We have also discussed the role of internal heating as well as anisotropy on the heat transfer characteristics.

12

Development and validation of HPLC assay method for marbofloxacin determination in veterinary chewable tablets

45%

Oliveira K. R. W. , Sversut R. A. , Singh A. K. , Amaral M. S. , Kassab N. M.

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2019

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tom Vol. 31, no. 4

291--293

EN

The present study aimed to develop and validate an analytical method for determination of marbofloxacin (MAR) in veterinary chewable tablets. The isocratic reversed-phase chromatographic method was developed and validated using a Vertisep®, RP C18 column (150 mm × 4.6 mm, 5.0 μm). The mobile phase was composed of water–acetonitrile (55:45, v/v) with pH adjusted to 3.0 with ortho-phosphoric acid and a flow rate set at 0.4 mL/min. The proposed method was validated for linearity in a concentration range of 2.5 to 17.5 μg/mL with a correlation coefficient of 0.99991. The mean content of MAR found in chewable tablets was 104.40% with RSD below 2%. The accuracy expressed as average recovery of the proposed method was 98.74%, and the precision expressed as relative standard deviation among repeated analysis was 0.55%. The method has adequate sensitivity with detection and quantitation limits of 0.25 and 0.81 μg/mL, respectively. Based on the presented results and according to the ICH and AOAC guidelines on validation of analytical methods, the proposed method was considered precise, accurate with adequate sensitivity, and robust in the MAR quantitative analysis. Therefore, the method can be used in the quality control of chewable veterinary tablets containing MAR.

13

An improved method of DNA purification from secondary metabolites rich medicinal plants using certain chaotropic agents

38%

Ghadia B. , Singh A. K. , Khatnani T. , Hirpara M. , Patel S. , Joshi P.

Acta Physiologiae Plantarum

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2016

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tom 38

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nr 08

14

Identification and characterization of a small heat shock protein 17.9-CII gene from faba bean (Vicia faba L.)

38%

Kumar R. , Lavania D. , Singh A. K. , Negi M. , Siddiqui M. H. , Al-Whaibi M. H. , Grover A.

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nr 09

EN

We cloned and characterized the full-length coding sequence of a small heat shock protein 17.9 gene from faba bean encoding 160 amino acids and containing the conserved a-crystallin domain at the C-terminus. Homology and phylogenetic analysis suggested its proximity with the class II sHsp members of fabaceae family. Therefore, we name this gene as VfHsp17.9-CII. The VfHsp17.9-CII transcript showed a clear heat stress induction pattern in leaves of young seedlings and flowering plants. Transient expression of VfHsp17.9-CII fused with green fluorescent protein reporter indicated its nuclear localization. Overexpression of recombinant VfHsp17.9- CII protein in Escherichia coli cells increased tolerance of the bacterial cells to heat and arsenic stresses. The reduction of faba bean pollen viability in response to heat stress correlated with the accumulation pattern of VfHsp17.9-CII transcript in heat stressed pollen. It is suggested that VfHsp17.9-CII protein plays a key role in heat and heavy metal stress tolerance.

15

A study on extracellular synthesis of silver nanoparticles from endophytic fungi, isolated from ethanomedicinal plants Curcuma longa and Catharanthus roseus

38%

Singh D. , Rathod V. , Singh A. K. , Haq M. U. , Mathew J. , Kulkarni P.

International Letters of Natural Sciences

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2016

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tom 57

EN

Biological method is considered as eco-friendly and reliable process for the synthesis of silver nanoparticles (AgNps) in the field of nanotechnology due to its tremendous applications in various fields. In this study we have isolated a total of twelve endophytic fungi from leaves of Curcuma longa (turmeric) and Catharanthus roseus out of which six endophytic fungi showed their ability to synthesized AgNps from silver nitrate (AgNO3) solution which splits into a positive silver ion (Ag+) and a negative nitrate ion (NO3 -) in order to turn the silver ions into solid silver (Agº). Of the six positive endophytic fungi VRD2 showed good and encouraging results and was identified as Penicillium spinulosum VRD2. UV-Visible Spectroscopy confirms the AgNps showing maximum peak at 425nm implying the bioreduction of AgNO3. Transmission Electron Microscopy (TEM) revealed the particle are spherical and well dispersed without agglomeration size ranging from 25- 30nm.