Browsing by Author "S.N. Upadhyay"

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Active cadmium sulfide photocatalysts for hydrogen production from water
(American Chemical Society, 1998) Manjit K. Arora; A.S.K. Sinha; S.N. Upadhyay
Cadmium sulfide photocatalysts for H2 production from water using visible light were prepared by different techniques, i.e., liquid-liquid, gas-liquid, and solid-liquid reactions. The crystallite size and distribution, band gap, and stoichiometric composition of cadmium sulfide and consequently the activity were affected by the preparation technique. The activity of cadmium sulfide showed a strong correlation with its semiconducting (n- or p-type) behavior. Cadmium sulfide that was prepared by gas-solid reaction had excess interstitial cadmium ions in the lattice, which had been attributed to its n-type semiconductor behavior and superior activity. The n-type behavior of cadmium sulfide has been correlated to its stoichiometry. © 1998 American Chemical Society.
Alumina nanoparticles for the removal of Ni(II) from aqueous solutions
(2008) Y.C. Sharma; V. Srivastava; S.N. Upadhyay; C.H. Weng
Alumina nanoparticles were developed by the sol-gel method and were used for the removal of Ni(II) ions from aqueous solutions. The nanoparticles were characterized by TEM and XRD. Nanoparticles of alumina were then used for removal of Ni(II) ions from aqueous solutions of nickel. The nanosize of the adsorbent was confirmed by TEM and XRD. Removal (%) was found to be dependent on the initial concentration of nickel, and maximum removal was found to be 96.6% at 25 mg/L Ni(II). The removal increased from 99 to 99.6% by decreasing the initial concentration from 75 to 25 mg/L. Equilibrium time was found to be 120 min. As expected, higher removal was obtained at higher adsorbent dose. The removal was governed by first-order kinetics, and the value of the rate constant of adsorption was found to be 1.83 × 10-2 min-1 at 25 mg/L and 25°C. The removal was found to be pH dependent, and maximum removal was found to be at pH 8.0. The adsorption process was endothermic in nature. The experimental data fit well the Langmuir and Freundlich isotherms. Constants of the two isotherm equations were determined. Thermodynamic studies for the present process were performed by determining the values of ΔG̊, ΔH̊, and ΔS̊ at different temperatures. © 2008 American Chemical Society.
An economically viable removal of methylene blue by adsorption on activated carbon prepared from rice husk
(2011) Y.C. Sharma; Uma; S.N. Upadhyay
Application of an agricultural waste material, rice husk, has been investigated for preparation of activated carbon. The rice husk-activated carbon (RHAC) was successfully utilised for the removal of a cationic dye, methylene blue (MB) from aqueous solutions. The activated carbon was prepared in presence of ZnCl2 as an activating agent under inert nitrogen atmosphere. RHAC was characterised for surface area, pore structural parameters, and point zero charge (pHZPC). The activated carbon was further characterised by Fourier transformation infrared (FT-IR) spectrometer, X-ray diffractometer (XRD), and scanning electron microscope (SEM). The effect of different parameters such as contact time and initial concentration, adsorbent dose, and temperature on removal of the dye from aqueous solutions was investigated. The experimental data fitted well in both the Freundlich and Langmuir isotherm models. The maximum adsorption capacity for MB was found to be 9.73mgg-1 at 303K. During the study of effect of adsorbent dose, almost a 100% removal was achieved at a higher dose of RHAC. Most of the experiments were carried out at an initial concentration of MB of 60mg/L and at 303K. Different thermodynamic parameters, viz., changes in free energy (G°), enthalpy (H°), and entropy (S°) have also been determined to explain feasibility of the process of removal. The sorption of MB on RHAC was found to be feasible, spontaneous, and endothermic in nature. © 2010 Canadian Society for Chemical Engineering.
Anxiolytic activity of piracetam, a nootropic agent, following subchronic administration in rodents
(1993) S.K. Bhattacharya; A.P. Sen; S.N. Upadhyay; A.K. Jaiswal
Piracetam (PIR), a cyclic GABA derivative without GABA-mimetic activity, is classified as a nootropic agent, a new class of psychotropic drugs which augment learning acquisition and retention of memory. The present study indicates that PIR has significant anxiolytic activity in rodents following subchronic, but not acute administration, when tested against several paradigms of experimental anxiety. Thus, PIR (250 and 500 mg/kg), administered orally for 7 and 14 days, exhibited anxiolytic activity in the open-field, elevated plus-maze and footshock-induced fighting in paired mice paradigms, as well as in the Vogel's conflict test in rats. In addition, PIR induced significant reduction in rat brain tribulin levels, a putative endocoid marker for anxiety, produced by pentylenetetrazole, an anxiogenic agent. On the contrary, single acute administration of PIR failed to induce any anxiolytic effect. The present study, thus, confirms clinical reports that PIR can induce a delayed antianxiety effect in psychogeriatric individuals and in chronic alcoholism.
Bio-filtration of trichloroethylene using diazotrophic bacterial community
(Elsevier Ltd, 2010) Awadhesh K. Shukla; Pranjali Vishwakarma; R.S. Singh; S.N. Upadhyay; Suresh K. Dubey
Biodegradation of TCE was studied in a biofilter packed with wood charcoal and inoculated with diazotrophic bacterial community isolated from local soil. Steady state TCE removal efficiencies higher than 85% were observed up to inlet load of 2.866 g m-3 h-1. The maximum elimination capacity of 5.31 gm-3 h-1 was observed at an inlet load of more than 7.90 g m-3 h-1. The biofilter was sensitive to fluctuations in the process conditions but could easily recover its performance after 10 days shutdown. Almost constant and small pressure drop per unit length and very negligible compaction was observed during the whole experimental period. The molecular analyses such as RT-PCR and gene sequencing revealed the presence of functionally active Azospirillum species in the biofilm. © 2009 Elsevier Ltd. All rights reserved.
Bio-methanol as a renewable fuel from waste biomass: Current trends and future perspective
(Elsevier Ltd, 2020) Pallavi Gautam; Neha; S.N. Upadhyay; S.K. Dubey
Use of abundantly available virgin and waste biomasses as feed-stock for producing gaseous (bio-gas) and liquid fuels (bio-methanol, bio-ethanol and bio-butanol) is being considered as the sustainable and viable alternative to fossil fuels (coal, natural gas and petro-fuels like gasoline and diesel). Out of these bio-methanol is being considered as an attractive liquid fuel as well as feed-stock for the synthesis of enumerable valuable organic compounds currently being produced from coal, natural gas, and petroleum feed stocks. This review presents an overview of various thermo-chemical and biochemical routes that are being explored for the sustainable production of bio-methanol from waste biomass. The advantages and limitations of both the routes are discussed to provide a brief account of their basic principles and also indicate the issues to be addressed through further technological up-gradations for satiating the future energy demand. It focuses specially on the biochemical conversion route which utilizes microbes as biocatalysts for methanol production under normal temperature and pressure conditions. Available information on various process parameters affecting microbial production of bio-methanol have been critically reviewed. To make the process cost effective certain improvements like utilization of raw biogas instead of natural gas for methanol production and development of methane-utilizing microbes through genetic engineering as the subject for future research are discussed. The gap existing in the current knowledge that needs to be bridged to facilitate development of technology for large scale production of bio-methanol at an economical rate to meet the future demands are also pointed out. © 2020 Elsevier Ltd
Biodegradation of trichloroethylene (TCE) by methanotrophic community
(2009) Awadhesh K. Shukla; Pranjali Vishwakarma; S.N. Upadhyay; Anil K Tripathi; H.C. Prasana; Suresh K. Dubey
Laboratory incubation experiments were carried out to assess the potential of methanotrophic culture for degrading TCE. Measurements of the growth rate and TCE degradation showed that the methanotrophs not only grew in presence of TCE but also degraded TCE. The rate of TCE degradation was found to be 0.19 ppm h-1. The reverse transcriptase-PCR test was conducted to quantify expression of pmoA and mmoX genes. RT-PCR revealed expression of pmoA gene only. This observation provides evidence that the pmoA gene was functionally active for pMMO enzyme during the study. The diversity of the methanotrophs involved in TCE degradation was assessed by PCR amplification, cloning, restriction fragment length polymorphism and phylogenetic analysis of pmoA genes. Results suggested the occurrence of nine different phylotypes belonging to Type II methanotrophs in the enriched cultures. Out of the nine, five clustered with, genera Methylocystis and rest got clustered in to a separate group. © 2008 Elsevier Ltd. All rights reserved.
Biofiltration of xylene using wood charcoal as the biofilter media under transient and high loading conditions
(Elsevier Ltd, 2017) Kiran Singh; B.S. Giri; Amrita Sahi; S.R. Geed; M.K. Kureel; Sanjay Singh; S.K. Dubey; B.N. Rai; Surendra Kumar; S.N. Upadhyay; R.S. Singh
The main objective of this study was to evaluate the performance of wood charcoal as biofilter media under transient and high loading condition. Biofiltration of xylene was investigated for 150 days in a laboratory scale unit packed with wood charcoal and inoculated with mixed microbial culture at the xylene loading rates ranged from 12 to 553 g m−3 h−1. The kinetic analysis of the xylene revealed absence of substrate inhibition and possibility of achieving higher elimination under optimum condition. The pH, temperature, pressure drop and CO2 production rate were regularly monitored during the experiments. Throughout experimental period, the removal efficiency (RE) was found to be in the range of 65–98.7% and the maximum elimination capacity (EC) was 405.7 g m−3 h−1. Molecular characterization results show Bacillus sp. as dominating microbial group in the biofilm. © 2017 Elsevier Ltd
Catalysis for energy
(2006) Shailendra Tripathi; A.S.K. Sinha; S.N. Upadhyay
[No abstract available]
Changes in methanogenic population size and CH4 production potential in response to crop phenology in tropical rice field
(2013) Suresh K. Dubey; Alpana Singh; R.S. Singh; S.N. Upadhyay
In order to understand the microbial ecology of CH4 production in rice field, population size of methanogens and pattern of CH4 production potential was determined during rice cultivation for two years (2009 and 2010). Population size varied between 4.88 × 105 and 13.98 × 105 copies g-1 dws during the entire study period and followed the trend: flowering > ripening > tillering > post-harvest > pre-plantation. Pattern of CH4 production potential was similar to the population size for different stages of the crop and followed the pseudo-first order kinetics, indicating a positive relationship between the population size of methanogens and CH4 production potential. An exponential relationship between the cumulative methane production potential and methanogenic population size was established. © 2012 Elsevier Ltd.
Comparative effects of prenatal and postnatal undernutrition on learning and memory in rats
(National Institute of Science Communication, 1999) Arun K. Jaiswal; S.N. Upadhyay; K.S. Satyan; S.K. Bhattacharya
Effects of pre- and post-natal undernutrition on learning and memory parameters were studied in albino rats. Prenatal undernutrition was induced in rat pups by restricting the mother's diet by 50% during the entire gestation period, whereas postnatal undernutrition was induced in rat pups by restriction of their diet by rotating them between lactating and non- lactating maternalised females for 12hr each day during suckling period from 2nd day to 18th day after birth. At 2.5 to 3 months of age all the rat offsprings were subjected to (i) original and reversal discrimination learning, (ii) passive avoidance, and (iii) active avoidance and its retention tests. The results indicate that both pre- and post-natal undernutrition in rat pups caused significant deficits in original and reversal discrimination learning, retention of passive avoidance after one week retention interval, and retention of active of avoidance learning. However, both pre- and post-natal undernutrition did not show significant effect on acquisition of active avoidance and retention of passive avoidance after 24hr retention interval.
Computer simulation of membrane processes: Ultrafiltration and dialysis units
(Elsevier Science Ltd, 2000) Vineet Kumar; S.N. Upadhyay
An algorithm for computer simulation of membrane processes such as ultrafiltration and dialysis has been developed using a simplified finite volume approach. The technique used is slightly different from the standard finite difference, finite volume and finite element methods where all the parameters are considered at fixed nodal points. In the present approach the entire flow chamber is divided into a large number of volume elements and each element is considered to be an independent unit (similar to finite volume method). All mass flux and velocity components are calculated at the boundaries whereas concentration is considered at the center of the element. Thus, unlike FDM, FVM, and FEM, in the present approach nodal points for velocity and concentration are different. It has been observed that this method is more accurate and fast and requires less computational effort. (C) 2000 Elsevier Science Ltd. All rights reserved.; An algorithm for computer simulation of membrane processes such as ultrafiltration and dialysis has been developed using a simplified finite volume approach. The technique used is slightly different from the standard finite difference, finite volume and finite element methods where all the parameters are considered at fixed nodal points. In the present approach the entire flow chamber is divided into a large number of volume elements and each element is considered to be an independent unit (similar to finite volume method). All mass flux and velocity components are calculated at the boundaries whereas concentration is considered at the center of the element. Thus, unlike FDM, FVM, and FEM, in the present approach nodal points for velocity and concentration are different. It has been observed that this method is more accurate and fast and requires less computational effort.
Degradation kinetics of chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP) by fungal communities
(Elsevier Ltd, 2012) K. Maya; S.N. Upadhyay; R.S. Singh; Suresh K. Dubey
Fungal isolates obtained from soil were used for degrading chlorpyrifos (CP) and TCP. The percentage degradation ranged from 69.4 to 89.8 for CP and 62.2 to 92.6 for TCP after one week. The values of Ks and Vmax were different for different isolates. The Ks ranged from 66.66 to 169.5 mg/L and Vmax from 6.56 to 40.4 mg/L/d for CP and from 53.19 to 163.9 mg/L and 3.41 to 40.40 mg/L/d, respectively, for TCP. Fungal community showed high affinity for both CP and TCP. The genetic relatedness of isolate F1 to Aspergillus sp., F2 and F3 to Penicillium sp., F4 to Eurotium sp. and F5 to Emericella sp. were confirmed. The degradation potential was in the order: F1 > F2 = F3 > F4 > F5. © 2012 Elsevier Ltd
Diffusion and mass transfer from a rotating disk in aqueous polymeric solutions
(1980) P. Lal; P. Mishra; S.N. Upadhyay
Laminar flow mass transfer data from the surface of rotating disks have been used to calculate diffusion coefficients of benzoic acid in aq. solutions of carboxymethyl cellulose (CMC). In the range studied the diffusion coefficient has been shown to decrease with increasing polymer concentration and to be independent of shear rate. The ratio of the diffusivity in polymer solution to that in water is a function of the square root of the polymer concentration and for benzoic acid-aq. CMC solution it can be expressed as DM,sol DM,water=10-0.964 C. © 1980.
Diffusion Coefficient in Aqueous Polymer Solutions
(1991) U.K. Ghosh; S. Kumar; S.N. Upadhyay
The diffusion coefficients for benzoic add in a number of aqueous solutions of poly(vinyl alcohol) (3.0 and 6.0% polymer by weight) and poly (ethylene oxide) (0.75-3.5% polymer by weight) are reported. The diffusivity values are obtained by measuring the rate of mass transfer of benzoic acid from the surfaces of rotating disks. Data on solubility of benzoic acid in poly(ethylene oxide) are also reported. The diffusivities in the polymer solutions are found to be Independent of shear rate and are lower than those in water. © 1991, American Chemical Society. All rights reserved.
Effect of chemical treatment on thermal degradation behavior of litchi seed biomass
(Springer Science and Business Media B.V., 2023) Mohit Kumar; Rahul Yadav; Amit Kumar Patel; Munish Bindal; S.N. Upadhyay; P.K. Mishra
Litchi tree is planted in several countries of the world for its juicy fruit. For the estimated total annual global litchi production of ~ 2.7 million tons, around ~ 0.54 million tons of seeds as well as a sizeable amount of skin are generated as waste. This renewable waste biomass can be effectively used as the feedstock for recovering energy and obtaining several value-added products. In the present work, the fuel and thermochemical characteristics and thermal degradation behavior of acid- and alkali-treated litchi seed biomass were systematically investigated and compared for the first time. The average and maximum rate of mass losses, peak temperature and pyrolysis factor had been evaluated to assess the reactivity of the treated biomass. It had been observed that acid and alkali treatments improved the higher heating value and changed the thermal degradation behavior. The thermogravimetric (TG)/differential thermogravimetric analysis (DTG) data obtained at the heating rates of 20, 25 and 30 °C min−1 were used to evaluate the kinetic and thermodynamic parameters using iso-conversional models of Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Tang and Starink. The Criado method had been used to elucidate the prevailing thermal degradation reaction mechanisms at different fractional conversions. The average activation energy of the acid-treated biomass increased, and that of the alkali-treated biomass decreased compared to that of the untreated biomass. Graphical abstract: [Figure not available: see fulltext.] © 2023, Akadémiai Kiadó, Budapest, Hungary.
Effect of dihydroergotoxine, a cerebral vasodilator, on cognitive deficits induced by prenatal undernutrition and environmental impoverishment in young rats
(1991) A.K. Jaiswal; S.N. Upadhyay; S.K. Bhattacharya
[No abstract available]
Effect of Dispersion and Distribution on Activity of Alumina-Supported Cadmium Sulfide Photocatalysts for Hydrogen Production from Water
(American Chemical Society, 1998) Manjit K. Arora; A.S.K. Sinha; S.N. Upadhyay
Activity of a cadmium sulfide photocatalyst, for hydrogen production by decomposition of water using visible light, depends on the protocol used for its preparation. In the present work, unsupported and alumina-supported CdS photocatalysts were prepared by various techniques and characterized by N2 adsorption, X-ray diffraction, electron diffraction, and X-ray photoelectron spectroscopy. The results indicate that the activity is strongly affected by the dispersion and distribution of CdS on alumina. High dispersion and preferential distribution of CdS on the surface of alumina yield superior activity. The catalyst activity has been explained with the help of its microstructure.
Effect of piracetam on electroshock induced amnesia and decrease in brain acetylcholine in rats
(1993) S.K. Bhattacharya; S.N. Upadhyay; A.K. Jaiswal
Piracetam, a prototype of a new class of psychotropic agents, the nootropic agents, which improve learning ability and memory retention, was found to induce a dose-related prevention of disruption of acquisition of a passive avoidance response produced by electroshock application. The amnesia attenuating effect of piracetam was accompanied by prevention of the decrease in acetylcholine concentrations of rat brain induced by electroshock. The study indicates that the cognition enhancing effect of piracetam may be due to a facilitatory effect on cholinergic transmission.
Effect of piracetam, a nootropic agent, on discrimination learning deficits induced by parental undernutrition and environmental impoverishment in young rats
(1989) A.K. Jaiswal; S.N. Upadhyay; S.K. Bhattacharya
[No abstract available]