Browsing by Author "R.K. Yadav"

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Advancements in the utilization of Azolla-Anabaena system in relation to sustainable agricultural practices
(Indian National Science Academy, 2014) R.K. Yadav; G. Abraham; Y.V. Singh; P.K. Singh
The nitrogen fixing aquatic pteridophyte Azolla has the ability to fix atmospheric nitrogen at cheaper and faster rates due to the presence of a symbiotic cyanobacteriumAnabaena azollae. Because of this property it has been exploited widely as biofertilizer for rice plants. In addition to this it has several other uses such as food, feed, biogas producer and hyperaccumulator of heavy metals etc. Because of the multifaceted uses the promotion and use of Azolla-Anabaena system would be ideal and environment friendly in sustainable agriculture. This article provides a brief account of the importance as well as developments in the utilization of Azolla-Anabaena system in agriculture and allied sectors. © Printed in India.
Backscattering of 8-28 keV electrons from a thick Al, Ti, Ag and Pt targets
(2006) R.K. Yadav; R. Shanker
Measurements of electron backscattering coefficient η for thick Al, Ti, Ag and Pt targets have been made for incident electrons with energy 8-28 keV. The variations of η with angle of incidence α, impact energy E 0 and with target atomic number Z have been studied. The data are compared with available theories. The mean fractional energy absorbed in the backscattering process has been determined and compared with an analytical expression and with Monte-Carlo simulations based on the Kanaya and Okayama electron-electron and electron-nucleus interactions and on the Quinn electron-plasma interactions. The comparison between our experimental data and the model calculations using Monte-Carlo simulations and analytical expression shows a reasonably good agreement among themselves within experimental errors of measurements. © 2005 Elsevier B.V. All rights reserved.
Backscattering of 8-28 keV electrons from a thick tungsten target
(2003) R.K. Yadav; Argala Srivastava; S. Mondal; R. Shanker
The backscattering process of 8-28 keV electrons from a thick tungsten target is studied. Measurements on the variation of the backscattering coefficient, η, with angle of incidence α and with diffusion range xd for different impact energies are presented and discussed. Simple analytical expressions based on continuous energy-loss and diffusion of incident electrons inside the target are used to examine the above variations. Over the entire ranges of impact energy and angle of incidence of the present studies, the predictions of the analytical relations are found to be in good agreement with most of our data and with those of earlier workers within experimental errors of measurement.
Bremsstrahlung spectra produced from kilovolt electrons incident on thick targets of Ti, W and Pt
(Institute of Physics Publishing, 2008) A.N. Agnihotri; V.S. Subrahmanyam; R.K. Yadav; R. Shanker; X. Llovet
Measurements of x-ray emission spectra generated by 10-20 keV electrons impinging normally on bulk targets of pure elements Ti (Z = 22), W (Z = 74) and Pt (Z = 78) have been performed using an experimental setup developed for studying electron-atom/molecule collisions in our laboratory. Values extracted from the experimental data for bremsstrahlung yield, integrated yield and mean energy of the bremsstrahlung radiation beam for the above collision systems have been compared with the simulation results obtained from the general purpose Monte Carlo simulation code PENELOPE. The comparisons are found to show a satisfactory agreement between them within their statistical uncertainties. Some apparent mismatches are observed for which possible causes and their origins are discussed. © 2008 IOP Publishing Ltd.
Comments on “Investigations on a novel biologically active organic molecule of 5-Chloro-1-(4-piperidyl)-2-benzimidazolinone by spectroscopic, molecular docking, and quantum chemical approach”
(Elsevier B.V., 2024) R.K. Yadav; R.A. Yadav
The conformational analysis for the 5-Chloro-1-(4-piperidyl)-2-benzimidazolinone molecule reported earlier [R. Arivazhagan, C. Sridevi, A. Prakasam, Investigations on a novel biologically active organic molecule of 5-Chloro-1-(4-piperidyl)-2-benzimidazolinone by spectroscopic, molecular docking, and quantum chemical approach, J. Mol. Struct. 1274 (2023) 134,544, 14 pages.] is incorrect. In the present communication we report briefly the correct conformational analysis. We have also discussed in brief the possible implications on different molecular properties on account of different molecular structures of the lowest energy conformer. © 2023
Contribution of backscattered electrons to the total electron yield produced in collisions of 8-28 keV electrons with tungsten
(2007) R.K. Yadav; R. Shanker
It is shown experimentally that under energetic electron bombardment the backscattered electrons from solid targets contribute significantly (∼80%) to the observed total electron yield, even for targets of high backscattering coefficients. It is further found that for tungsten (Z = 74) with a backscattering coefficient of about 0.50, about 20% of the total electron yield is contributed by the total secondary electrons for impact energies in the range of 8-28 keV. The yield of true backscattered electrons at normal incidence (η0), total secondary electrons (δ) and the total electron yield (δtot) produced in collisions of 8-28 keV electrons with W have been measured and compared with predictions of available theories. The present results indicate that the constant-loss of primary electrons in the target plays a significant role in producing the secondary electrons and that it yields a better fit to the experiment compared to the power-law. © Indian Academy of Sciences.
Effect of blending soymilk with buffalo milk on the quality of Paneer
(2010) J. Singh; Tanveer Alam; P. Srivastava; R.K. Yadav
Research experiments were carried out for the production of Paneer (Indian Cheese) by utilizing soymilk admixed with buffalo milk to evaluate its quality. Four different combinations of soymilk (0%:T0, 15%:T1 25%:T2 and 35 %:T3) in buffalo milk were taken to prepare soy-Paneer during experimentation. Three coagulation temperatures of 70, 80 and 90 °C were studied using citric and lactic acids as coagulants. The yield of soy-Paneer and their yield, fat and protein contents were increased (P< 0.05) in citric acid groups at 90°C than the Paneer prepare from lactic acid at 70 and 80°C. The yield of Paneer and their fat content decreased (P<0.05) as soymilk increased in the mixture.
Energy and angular distributions of backscattered electrons from collisions of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets
(2007) R.K. Yadav; R. Shanker
The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between EB = 50 eV and 5000 eV. The angle of incidence α and take-off angle 9 are chosen to have values α = 0° and 10° and θ = 100°, 110° and 120° respectively. The measured energy spectra are compared with the available theoretical models for α = 0° and 10°. The elastic peak intensity of backscattered electrons is found to be a function of angle of incidence, take-off angle and atomic number of the target material. The considered theories are reasonably in good agreement with experiment for the energy spectra of the backscattered electrons having their reduced energies ε(= EB/E0) in the range of 0.20 to 1.00. © Indian Academy of Sciences.
Energy and angular distributions of backscattered electrons from the collision of 8-keV electrons with a thick tungsten target
(2004) R.K. Yadav; R. Shanker
A 45° parallel plate electrostatic analyzer was used to measure the energy and angular distributions of backscattered electrons under the impact of 8.0-keV electrons. The energy range of backscattered electrons was considered between 70 and 1700 eV. The results of the two measured energy spectra were compared with two theoretical models. Two distinct Auger peaks appearing at 216 and 548 eV were exhibited by the energy spectra. The results show the cross sections of energy spectra for the large angle of incidence to be relatively larger than for those at low angle of incidence.
Fine needle aspiration cytology in the diagnosis of prostatic enlargements.
(1992) N.C. Aryya; R.K. Yadav; P.B. Singh; S. Khanna; K. Pandey
One hundred patients with enlarged prostate were subjected to fine needle aspiration cytology and histopathologic examination of prostate. The results have been found encouraging. The cytodiagnostic accuracy rate was 99 p.c. in identification of benign or malignant nature of the lesions and 94 p.c. in cytologic specific diagnosis (exactly similar to histopathologic diagnosis). The technique was simple, rapid, economical, reliable, easy to repeat and highly suitable for outpatients. The procedure can routinely be adopted in places where facilities for preparation of paraffin section do not exist or when quick diagnosis is required.
Force field calculations for 2-amino-5-chloro- and 2-amino-5-bromo-benzotrifluorides
(2006) R.A. Yadav; R.K. Yadav; N.P. Singh
Force field calculations have been carried out for 2-amino-5-chloro- and 2-amino-5-bromo-benzotrifluorides using the earlier (Ref. [47] of this article) reported IR and Raman spectra. As the frequencies of the corresponding modes for the C-Br and the C-Cl groups do not differ widely the two molecules are assumed to be isotopomers for the purpose of the force field calculations. The calculated and the observed frequencies match nicely for both the molecules. Consistent assignments have been proposed for the ring modes and the internal modes of the CF3 and the NH2 groups based on the potential energy distributions (PEDs), the IR and the Raman intensities and the depolarisation ratios of the Raman lines. © 2005.
Ion transport in proton conducting solid polymer electrolytes
(Institute for Ionics, 1998) P.N. Gupta; K.P. Singh; R.K. Yadav
In this communication the ion transport properties of polyvinyl alcohol complexed with orthophosphoric acid (H3PO4) have been investigated. The proton conduction is confirmed by hydrogen gas evolved at the cathode of the coulometer and the transference number of H+ ion has been determined. The transient ionic current (TIC) technique has been used to detect the mobile ionic species and their mobilities are evaluated. The ionic mobility was found to be of the order of 10-4 cm2.V -1.s-1 for H+ ions. It is observed that the bulk electrical conductivity increases with the temperature following the Arrhenius type behaviour. Variation of charge carrier concentration with the molar ratio of H3PO4 in the sample reveals that the carrier concentration is largely affected by the amount of dopant in the complexes.
Relative backscattering yields for electrons and positrons from tungsten at keV energies
(2006) R.K. Yadav; R. Shanker
The backscattering coefficients (η0-, η 0+) and their ratios for impact of 8-28 keV electrons and positrons with a thick tungsten target at normal incidence, have been determined and compared with the available data on W and Au targets. It is found that the backscattering ratios attain a constant value of about 1.35 at higher impact energies while they are seen to rise significantly at the lower impact energies. The measurements of backscattering yields at three different scattering angles, namely, at χ = 110°, 120° and 130° for normal incidence of 8 keV electrons with a thick tungsten target, have been made. The measured relative yields are studied as a function of χ and they are compared with the available data from other workers. The compared data are found to be in good agreement with each other and to follow a well known Lambert's cosine-law within the experimental uncertainty of measurements. © 2006 IACS.