BHU Institutional Repository :: Browsing by Author "Pandey, R.N."

Browsing by Author "Pandey, R.N."

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Asymptotic expansions of the Mehler-Fock transform
(Springer India, 1989) Pathak, R.S.; Pandey, R.N.
Asymptotic expansions in the two limits x → + ∞ and x → 0+ are obtained for the Mehler-Fock transform {Mathematical expression} where P -1/2+ir m (cosh x) is the associated Legendre function. © 1989 Indian Academy of Sciences.
Behaviour of some copper(ii) salts in propylene carbonate. Standard electrode potential of the Cu2+/Cu system at 25° c
(1988) Pandey, R.N.; Srivastava, A.K.; Bapat, M.G.
The behaviour of Cu(ClO4)2, CuCl2 and CuBr2 in propylene carbonate (PC) has been studied with conductance and potential measurements. The conductance behaviour of CuCl2 and CuBr2 in PC is explained on the basis of the equilibria 3 CuX2 ⇋ Cu2+ +2 CuX-3 and 2 CuX2 ⇋ (CuX2)2. In addition, a copper indicator electrode in conjunction with a Hg/HgCl2(s) in PC reference electrode was used for potential measurements. The results of the potential measurements, combined with those of the conductance measurements, provide the standard potential of the reaction Cu2+(solv) + 2 e- ⇋ Cu(s) vs. SHE in PC at 25 °C. It was found to 0.1546 ±0.0026 V. © 1988.
Behaviour of some monocarboxylic acids in propylene carbonate: a conductance study
(1992) Pandey, R.N.; Bapat, M.G.
The results of conductance measurements of monochloroacetic, dichloroacetic, trichloroacetic, trifluoroacetic, p-chlorophenoxyacetic, 2-(p-chlo o-bromobenzoic and o-nitrobenzoic acids in propylene carbonate are reported. The observed conductance behaviour of these acids in propylene car -), homoconjugation (HA + A → HA2-) and dimerization (2HA → (HA)2) equilibria. The existence of dimers was found only in the ca Values of the constants of dissociation KHA, homoconjugation KHA and dimerization Kd have been obtained for these a. © 1992.
Complete and satisfactory solutions of Luikov equations of heat and moisture transport in a spherical capillary-porous body
(Elsevier Science Ltd, 2000) Pandey, R.N.; Pandey, S.K.; Ribeiro, J.W.
Available results based on the exact solutions of the Luikov system of coupled heat and moisture diffusion problems addressed to the boundary conditions of the third kind for the bodies of simple geometry, have been reconsidered and revised because the transcendental equations have countable number of complex conjugate roots under certain conditions, which were ignored in the original computations. A methodology, quite different from Lobo et al., is presented for evaluating a set of countable number of pairs of complex conjugate roots. The influence of complex eigenvalues on the temperature and moisture distributions in a spherical capillary porous body is demonstrated and benchmark results are obtained for reference purpose. © 2000 Elsevier Science Ltd.; Available results based on the exact solutions of the Luikov system of coupled heat and moisture diffusion problems addressed to the boundary conditions of the third kind for the bodies of simple geometry, have been reconsidered and revised because the transcendental equations have countable number of complex conjugate roots under certain conditions, which were ignored in the original computations. A methodology, quite different from Lobo et al., is presented for evaluating a set of countable number of pairs of complex conjugate roots. The influence of complex eigenvalues on the temperature and moisture distributions in a spherical capillary porous body is demonstrated and benchmark results are obtained for reference purpose.
Determination of drawdown and well function in case of finite nonleaky aquifer system. A new approach
(1989) Pandey, V.S.; Kunar, Sharad; Pandey, R.N.
This paper deals with the derivation of the expressions for drawdown and well function in case of transient radial flow in an isotropic nonleaky finite aquifer system with fully penetrating well and constant discharge condition using (i) Laplace transform technique (Exact method) and (ii) an algorithm developed by the authors (Approximate method). The numerical values of well function obtained by these two methods are depicted graphically and it is found that they compare excellently well.
Determination of steady state drawdowns in a horizontal double aquifer system - a new approach.
(1987) Pandey, V.S.; Pandey, S.K.; Pandey, R.N.
Using Ditkin's operator the exact analytical expressions for drawdowns for coupled 2 finite aquifer system in which pumpage from the upper and lower aquifer is balanced by a reduction in evapotranspiration from the upper aquifer are obtained. Also, the expressions for drawdowns for the limiting cases (viz. when the horizontal dimension of the aquifers is considered to be infinite) are deduced from one of the general results. -from Authors
Fractional Calculus and Its Applications Involving Certain Classes of Functional Relations
(1993) Pandey, R.N.; Srivastava, H.M.
An interesting functional relation between Fox's H-function and the Digamma function ψ(z) was derived recently by applying the Riemann-Liouville fractional differintegral operator of (real or complex) order μ The object of this paper is to present much simpler alternative derivations of substantially more general classes of functional relations without using fractional calculus. Some relevant historical details are also provided. © 1993 by the Massachusetts Institute of Technology.
High conversion efficiency photoelectrochemical solar cells
(Elsevier Ltd, 1996) Pandey, R.N.; Chandra Babu, K.S.; Srivastava, O.N.
The present review focusses on the prospectives and perspectives of high conversion efficiency photoelectrochemical (PEC) solar cells. The PEC solar cells score over their solid state counterparts on several points. Some of these are ease of fabrication and inbuilt storage capability. In order to make PEC solar cells viable, their conversion efficiencies need to be enhanced so as to reach optimum values. Several feasible efficiency enhancement processes for PEC cells such as electrode surface modification, photoetching, electrolyte modification etc. have been described and discussed in this article. The case of efficiency enhancement of n-GaAs based PEC solar cell through the modification of GaAs by Os3+ or Ru3+ ions leading to efficiency enhancement from 9 to 15% has been described and discussed. In regard to efficiency enhancement through electrolyte modification, the example of n-CdSe based PEC cell where the electrolyte (K3 Fe(CN)6 / K4 Fe(CN)6) is modified through KCN has been dealt with. The efficiency obtained in this cell is upto ∼ 16%. For the PEC solar cells embodying the d-d phototransition, MX2 type layered materials, the most dramatic conversion efficiency enhancements come through photoetching of electrode surfaces. We have described and discussed in detail the efficiency enhancements in n-WSe2 / I-3, I-/Pt solar cells through photoetching of n-WSe2 photoelectrodes in 0.1 M aquaregia. High efficiencies upto ∼ 17% have been obtained for those solar cells. Yet another route of fabricating viable PEC solar cells giving high power output corresponds to the development of newer PEC cell designs. One example of the newer cell designs which has been described and discussed in this article corresponds to semiconductor-septum (SC-SEP) PEC solar cell. The SC-SEP, PEC solar cells have been found to yield higher power outputs (Voc and Isc) than the conventional single compartment PEC cells. For example, n-CdSe/Ti septum based PEC solar cell with configuration - Pt, 1 M-3S//n-CdSe/ Ti//0.1M AgNO3, Pt has been found to give higher power output (1.42 V and 20 mA/cm2), as compared to n-CdSe based conventional PEC cell (0.64 V and 6 mA/cm2). Similarly, n-TiO2/Ti septum electrode based SC-SEP, cell - Pt, 1 M NaOH/n-TiO2/Ti/0.1M AgNO3, Pt also gives higher power output (1.2 V and 15 mA/cm2). The case of another new PEC cell design incorporating nanostructured TiO2 photoelectrode overlaid with special dye (Ruthenium trinuclear cyanide complex) and exhibiting efficiencies of 7% (under usual solar illumination) and 12% (in diffuse solar light) has also been outlined.
Investigations of electrolyte heating induced enhancement of the photoelectrochemical response in PEC solar cells based on n-WSe2 single crystals
(1991) Chandra, A.; Pandey, R.N.; Srivastava, O.N.; Prasad, G.
Very significant enhancements in photoelectrochemical activity, particularly the photocurrent (short circuit current), have been noticed when preheated (up to approximately 42 degrees C) electrolyte is used in PEC solar cells comprising a single crystal n-WSe2 photoelectrode with I -/I3- electrolyte. Current enhancements ranging from two to five times have been observed for different n-WSe2 photoelectrodes. It has been shown that this enhancement, although obtained through electrolyte heating, is a room temperature phenomenon and is invariably present for all the n-WSe2 photoelectrodes employed in the present investigation. Measurements of the various characteristics of the electrolyte and the crystal surface/interface reveal that the only feature which undergoes noticeable change is the flat band potential. Mott-Schottky plots reveal that a representative change in flat band potential is a shift from -0.41 V (native electrolyte) to -0.84 V (preheated electrolyte). The most likely cause of the enhancement is thought to be the formation of other polyiodides such as I 42- and I5- during cooling of the heated electrolyte and their consequent adsorption onto the crystal surface. This leads to passivation of surface states through the formation of complexes involving W4+ and I42- and/or I 5-. Such a passivation will reduce the density of recombination states leading to the observed enhancement in the photocurrent.
Linear theory of memory-dependent micropolar viscoelastic materials with stretch
(1978) Gupta, L.S.; Pandey, R.N.
A linear theory of memory-dependent micropolar viscoelastic materials with stretch has bean developed. Linear constitutive functionals have been considered to depend on the continuous past history of the strain measures, micro-rotation gradient, stretch and stretch gradients. The constitutive equations of isotronic linear micronolar viscoelastic materials with stretch have been obtained as a particular case by neglecting the past history of the motion. © 1978.
Solar hydrogen production employing n-TiO2/Ti SC-SEP, photoelectrochemical solar cell
(Elsevier Ltd, 1997) Misra, Mridula; Pandey, R.N.; Srivastava, O.N.
The present paper describes the fabrication and solar hydrogen production studies employing a new semiconductor-septum (SC-SEP) photoelectrode n-TiO2/Ti based photoelectrochemical solar cell with the configuration SCE/1 M NaOH/TiO2/Ti/H2SO4+K2SO 4/PtCE, PtWE. The monitoring of the current-voltage characteristics of the above SC-SEP cell revealed an enhancement in short-circuit current (ISC) up to three times (5-∼ 15 mAcm-2) that of its single compartment PEC cell counterpart based on the n-TiO2 photoelectrode. The rate of hydrogen production was found to change with variation in the concentration of the electrolyte in the dark compartment; e.g. for 1 M H2SO4 it is 6.31 1 h-1 m-2 and for 5 M it is 13.15 1 h-1 m-2. The optimum hydrogen production rate was found to be 13.15 1 h-1 m-2 for 5 M H2SO4. With a further increase in H2SO4 concentration, the hydrogen production rate was found to be invariant. The hydrogen production rate of TiO2/Ti based SC-SEP cells when compared with the only other known SC-SEP cell based on n-CdSe/Ti and corresponding to the configuration SCE/polysulfide +0.1 M selenium solute/n-CdSe/Ti/5 M H2SO4/PtCE, PtWE exhibits a hydrogen production rate higher by about 10 times. © 1997 International Association for Hydrogen Energy. All rights reserved.
Solar hydrogen production using semiconductor septum (n-CdSe/Ti and n-TiO2/Ti) electrode based photoelectrochemical solar cells
(Elsevier Ltd, 1998) Pandey, R.N.; Misra, M.; Srivastava, O.N.
In the present study, photoelectrochemical and hydrogen evolution characteristics of CdSe/Ti and TiO2/Ti based semiconductor-septum photoelectrochemical (SC-SEP, PEC) solar cell have been studied. The SC-SEP cell in the configuration of SCE, 1 M 3S//CdSe/Ti//5 M H2SO4, Pt(W), Pt(C), gave power output of 0.62 V and 11 mA cm-2, whereas the conventional Pt, 1 M 3S//CdSe/Ti, PEC cell gives power output of 0.64 V and 6 mA cm-2. The hydrogen evolution characteristics of SCE, 1 M 3S//CdSe/Ti//5 M H2SO4, Pt(W), Pt(C), exhibited a rate of 1.0 to 1.5 1 h-1 m-2 under an illumination intensity of 80 mW cm-2. The TiO2/Ti septum based SC-SEP solar cell in the configuration of SCE, 1 M NaOH//TiO2/Ti//5 M H2SO4, Pt(W), Pt(C), gives power output of 0.74 V and 14.5 mA cm-2 whereas the conventional Pt, 1 M NaOH//TiO2/Ti, PEC solar cell gives power output of 0.7 V and 5 mA cm-2. The hydrogen evolution characteristics of TiO2/Ti based SC-SEP cell measured in the configuration of SCE, 1 M NaOH//TiO2/Ti//5 M H2SO4, Pt(W), Pt(C), gave a hydrogen evolution rate of 10-15 1 h-1 m-2 under an illumination intensity of 450 mW cm-2. It has been shown in the present investigation that TiO2/Ti based SC-SEP solar cell is more stable and gives higher rate of hydrogen production compared to the CdSe/Ti based SC-SEP cell. Further studies to optimize the stability and other conditions for the production of solar hydrogen using these SC-SEP solar cells have been outlined. © 1998 International Association for Hydrogen Energy.
Solutions of Luikov equations of heat and mass transfer in capillary porous bodies through matrix calculus: A new approach
(Elsevier Sci Ltd, 1999) Pandey, R.N.; Srivastava, S.K.; Mikhailov, M.D.
In this paper an eigenvalue analysis approach is employed to obtain the solutions of the Luikov system of linear partial differential equations addressed to the most general type of boundary conditions. The Luikov equations provide a well established model for the analysis of various simultaneous heat and mass diffusion problems in capillary porous bodies. However, analytical methods to achieve a complete and satisfactory solution of these equations is still lacking in the literature because of noninclusion of the existence of a countable number of complex roots in almost all the solutions. A specific example on contact drying of a moist porous sheet with uniform initial temperature and moisture distribution is considered. The influence of the complex roots on the dimensionless temperature, moisture content, and the local rate of drying is demonstrated. A set of benchmark results is obtained for reference purposes.; In this paper an eigenvalue analysis approach is employed to obtain the solutions of the Luikov system of linear partial differential equations addressed to the most general type of boundary conditions. The Luikov equations provide a well established model for the analysis of various simultaneous heat and mass diffusion problems in capillary porous bodies. However, analytical methods to achieve a complete and satisfactory solution of these equations is still lacking in the literature because of noninclusion of the existence of a countable number of complex roots in almost all the solutions. A specific example on contact drying of a moist porous sheet with uniform initial temperature and moisture distribution is considered. The influence of the complex roots on the dimensionless temperature, moisture content, and the local rate of drying is demonstrated. A set of benchmark results is obtained for reference purposes.
Temperature and moisture distributions in a moist spherical capillary-porous body - A new approach
(John Wiley and Sons Ltd, 1999) Pandey, R.N.; Pandey, S.K.; Mikhailov, M.D.
A novel technique, which is a combination of the Laplace transform and matrix calculus, is employed to obtain the exact solutions of the linearized Luikov system of coupled heat and moisture transport equations in a spherical capillary porous body addressed to specified initial and boundary conditions. It is shown that under certain restrictions, in the case of convective-type boundary conditions, the transcendental equation yields a countable number of complex conjugate roots. Here, a new computational scheme is employed, which evaluates real as well as a countable number of pairs of complex conjugate roots. A set of benchmark results is generated for the Luikov drying model, and in a way better than the alternative solutions proposed by Lobo et al. [19] for linear problems. Copyright © 1999 John Wiley & Sons, Ltd.
Trichoderma: agricultural applications and beyond
(Elsevier, 2021) Pandey, R.N.; Jaisani, Pratik; Singh, H.B.
The filamentous fungal genus Trichoderma is the most common occurring fungus in soil and has the ability to colonize and multiply in various habitats. Trichoderma spp. are extensively used for biotic and abiotic stress management, crop growth enhancers, enzymes and antibiotics production/industrial uses, molecular biology, transgenic crop, metabolizers of xenobiotics, and commercial biofungicides etc. They possess multiple characteristics which qualify them as wonderful bioagents. The formulation of Trichoderma spp. are used in agriculture for seed treatment, foliar application and soil treatment for management of various diseases caused by fungi, bacteria and nematodes etc. Trichoderma is also used in bioremediation of heavy metal contamination, degradation of pesticide residue, This chapter deals with importance of Trichoderma, diversity, molecular taxonomy, its modes of action, methods of multiplication and application, challenges for wide scale adoption, regulatory requirements, bioremediation, decomposition of organic matter, wood preservation and biofuel. © 2022 Elsevier Inc. All rights reserved.

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