Browsing by Author "S.K. Tiwari"

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A review on antidiabetic action of asanadi gana
(International Journal of Research in Ayurveda and Pharmacy, 2013) Vandana Gupta; Bipin Bihari Keshari; S.K. Tiwari; K.H.H.V.S.S. Narasimha Murthy
Herbs and herbal drugs have created interest among the people due to their various clinically proven effects and lack of side effect. Moreover the overuse of synthetic drug which result in higher incidence of adverse drug reaction, has motivated the human to revert to nature for safer herbal medicines. The current review focuses on Asanadi gana (group of drugs) and its potential in the treatment of diabetes mellitus, a major crippling disease worldwide leading to huge economic loss. The review describes, various aspect of Asanadi gana like active phytoconstituents having hypoglycemic action, pharmacological properties and mechanism of action of its ingredients. This review also focuses on the traditional therapeutic action of the asanadi gana dravyas mentioned in ancient classics. In various pharmacological studies, done in last few decades on the drugs of asanadi gana dravyas, it has been proved that almost all the constituents of asanadi gana, posses anti hyperglycemic, hypolipidemic, antioxidant and other therapeutic properties.
Active thin NiCo2O4 film prepared on nickel by spray pyrolysis for oxygen evolution
(1995) S.K. Tiwari; S. Samuel; R.N. Singh; G. Poillerat; J.F. Koenig; P. Chartier
Thin films of NiCo2O4 were prepared on Ni at 370 °C by the method of spray pyrolysis. The films were uniform, adherent, free from cracks and electrocatalytically much more active for oxygen evolution than other NiCo2O4 films recently reported in the literature. This film electrode showed two Tafel slopes ~40 and ~120 mV decade-1 at low and high overpotential, respectively. The second-order observed kinetics in OH- concentration at lower overpotentials changed to first-order at higher overpotentials. A suitable mechanism involving the formation of a physisorbed hydrogen peroxide intermediate in a slow electrochemical step has been suggested. © 1994.
Anti-platelet aggregating activity of a polyherbal compound-shirishadi - In vitro study
(Oriental Scientific Publishing Company, 2017) Kajaria Divya; J.S. Tripathi; S.K. Tiwari
The present study aims to search a drug that acts on platelet aggregation to validate the fact that preventing platelet aggregation is helpful in successful management of bronchial asthma in addition with the effect on previously proved mechanism. With this aim it was planned to search the effect of a polyherbal drug - Shirishadi on platelet aggregation. It is worthy here to mention that this drug (Shirishadi) is chosen on the basis of clinical evidence suggesting its potent anti-asthmatic effect. Anti-platelet property of Shirishadi polyherbal compound was evaluated using thrombin induced platelet aggregation isolated from human blood (collected from healthy volunteers) by differential centrifugation. Under in vitro conditions, 15 min pre-incubation with the Shirishadi polyherbal compound (200μg/ml) significantly (p< 0.001) inhibit thrombin- induced platelet aggregation. These findings suggest that Shirishadi, a polyherbal formulation possesses potent anti-platelet aggregation activity in the experimental models of in vitro platelet aggregation. Copyright © 2017 Oriental Scientific Publishing Company.all rights reserved.
Assessment of Groundwater behavior in Kulpahar Watershed, District Mahoba, Uttar Pradesh, India
(IOP Publishing Ltd, 2020) A. Ram; S.K. Tiwari; H.K. Pandey; A.K. Chaurasia; S.K. Chaudhary
In hard rock terrain, the groundwater occurs in two zones viz. shallow zone (in overburden) and deeper fractured zones mainly through secondary porosity. The groundwater level through 23 observation wells (fifteen dug wells and eight piezometers) has been monitored during pre and post-monsoon periods. An attempt has been made to evaluate the impact of rainfall on the groundwater level in the hard rock area of Mahoba district in the Bundelkhand region. The study depicts the impact of rainfall over the long-term groundwater level trend and establishes a conceptual structure to understand the hydrological stress conditions. Due to overexploitation, the groundwater condition has reached to the category of a critical stage. The severity and duration of water-level responses to hydrologic stresses have been analyzed statistically as well as graphically. The groundwater level is spatially and temporally variable in hard rock area and essentially depends upon the amount of rainfall, geological condition, and topographic slope. The analyzed rainfall data have been graded as a good year and bad year based on the amount of precipitation. The long-term groundwater level trend (2006-2016) indicates a sharp decline in groundwater level trend in the western part due to higher base flow and poor recharge. On the other hand, due to the presence of thicker overburden and runoff accumulation therein, the groundwater level is rising in the northern part of the study area. It also validates that there is very fair control of slope and thickness of overburden on the groundwater regime apart from the rainfall. © Published under licence by IOP Publishing Ltd.
Decomposition studies of a liquisol quenched Al-33 at.% Mg alloy
(1979) S.K. Tiwari; K. Chattopadhyay; C. Suryanarayana; T.R. Anantharaman
X-ray and electron metallographic studies were undertaken on an aluminum-33 at.% magnesium alloy rapidly quenched from the melt by the "gun" technique. A small supersaturation of Mg in Al and two metastable intermediate phases were detected. These phases were found to display complex decomposition behavior on annealing at temperatures up to 300°C. © 1979.
Description of hot and dense hadron-gas properties in a new excluded-volume model
(American Physical Society, 2012) S.K. Tiwari; P.K. Srivastava; C.P. Singh
A new equation of state for a hot and dense hadron gas (HG) is obtained where the finite hard-core size of baryons has been incorporated into a thermodynamically consistent formulation of excluded volume correction. Our model differs from other existing approaches on the following points. We assign a hard-core volume only to each baryon and mesons, which, although they possess a small volume, can fuse and interpenetrate into one another. Use of the full quantum statistics is made to obtain the grand canonical partition function, where excluded-volume correction has been incorporated by explicitly integrating over volume. We thus find that the new model works even for cases of extreme temperatures and/or densities where most other approaches fail. The numerical calculation indicates that the causality is respected by our prescription even at extreme densities. The temperature and density dependences of various thermodynamical quantities, e.g., pressure, baryon density, entropy and energy density, compare well with the results of other microscopic HG models. After suitable parametrization of the center-of-mass energy in terms of temperature and baryon chemical potential, we explore some new freeze-out criteria which exhibit full independence of the collision energy and of the structures of the colliding nuclei. We further demonstrate the suitability of our model for explaining the various experimental results of the multiplicity ratios of various particles and their antiparticles. Finally, we use our excluded-volume model to obtain the transport behavior of a hot and/or dense HG, such as shear viscosity- to-entropy ratio and speed of sound, and compare the results with earlier calculations. © 2012 American Physical Society.
Effects of Ni, Fe, Cu, and Cr substitutions for Co in La0.8Sr0.2CoO3 on electrocatalytic properties for oxygen evolution
(Electrochemical Society Inc., 1996) S.K. Tiwari; S.P. Singh; R.N. Singh
The influence of some transition metal ion substitutions in the active 0.2 mole strontium-doped lanthanum cobaltate (La0.8Sr0.2Co1-yByO3 with B = Ni, Fe, Cu, and Cr; 0.1 ≤ y ≤ 0.4) lattice was studied on the electrocatalytic properties of the oxide by cyclic voltammetry and Tafel polarization techniques. The cyclic voltammetry showed a pair of redox peaks prior to the onset of oxygen evolution, regardless of the nature of the substitution. The presence of Fe or Ni, in small quantities, enhanced the electrochemically active area. The anodic polarization studies indicated two Tafel slopes: ∼2.3 RT/F at low and ∼2(2.3 RT/F) at high overpotentials. The oxygen evolution reaction on each B-site substituted perovskite followed first-order kinetics with respect to OH- ion concentration. The La0.8Sr0.2Co0.9Fe0.1O3 and La0.8Sr0.2Co0.9Ni0.1O3 electrodes showed the highest electrocatalytic activity based on geometrical surface area. Copper and chromium substitutions had detrimental effects on the electrocatalytic activity.
Effects of Ta, La and Nd additions on the corrosion behaviour of aluminium bronze in mineral acids
(Kluwer Academic Publishers, 1992) R.N. Singh; S.K. Tiwari; W.R. Singh
Corrosion studies of aluminium bronze with and without additions of Ta, La and Nd were carried out in HCl, HNO3 and H2SO4 solutions, using weight loss, polarization and impedance measurements. The study showed that the addition of each of Ta, La and Nd in small quantities effectively inhibited the corrosion of the alloy in HCl solution, the inhibition effect being greatest with low content of the alloying element. The inhibition of corrosion due to alloying additions was observed to be small in H2SO4 solution. In HNO3 medium, these alloying elements at low level showed slightly beneficial effects while they had adverse effects at higher concentrations. © 1992 Chapman & Hall.
Electro-catalytic activities of binary nano-composites of pt and nano-carbon/multiwall carbon nanotube for methanol electro-oxidation
(2010) R.N. Singh; R. Awasthi; S.K. Tiwari
Binary nano-composites of Pt and nano-carbon (NC) and Pt and multiwalled carbon nanotube (MWCNT) have been prepared with varied compositions ranging between 20 and 80wt% Pt and investigated them as electrocatalysts for methanol oxidation. The study shows that with the increase in wt% of NC, the apparent electro-catalytic activity of the composite catalyst increases initially, reaches maximum at about 40wt% NC and decreases thereafter. However, the anodic peak current value, estimated as per mg of Pt present in the composite, increases gradually with increasing wt% of NC in the composite. The electrochemical active surface area (EASA) value for Pt in the composite electrode also increases with increasing the carbon composition in the composite. Almost similar effect of the MWCNT addition on the electro-catalytic activity is also observed in the case of Pt-MWCNT composite. Results have shown that an incorporation of carbon (NC/MWCNT) improves both the geometrical as well as the electronic properties of Pt. © Singh et al.
Electrocatalysis of oxygen evolution/reduction on LaNiO3 prepared by a novel malic acid-aided method
(Springer Netherlands, 1998) S.K. Tiwari; J.F. Koenig; G. Poillerat; P. Chartier; R.N. Singh
A kinetic study of the electroformation and electroreduction of oxygen in KOH solutions has been carried out on a LaNiO3 electrode obtained through a malic acid precursor route. The new electrocatalyst was found to show greatly enhanced activity for both oxygen evolution and reduction. The apparent electrocatalytic activity of this electrode for oxygen reduction was more than 10 times higher than those reported for similar electrodes obtained by other methods. It was, however, observed to be less active electrocatalytically for oxygen evolution as compared to the active LaNiO3 electrode obtained by the Bockris-Otagawa coprecipitation method. The electrochemical reaction order with respect to OH- concentration was found to be approximately 1 in the case of oxygen evolution while that for oxygen reduction, was approximately -1. The Tafel slope values for the reactions were ∼2.3 RT/F and ∼2 × 2.3 RT/3F, respectively.
Electrocatalytic activity of high specific surface area perovskite-type LaNiO3 via sol-gel route for electrolytic oxygen evolution in alkaline solution
(Elsevier Ltd, 1997) R.N. Singh; S.K. Tiwari; S.P. Singh; A.N. Jain; N.K. Singh
Lanthanum nickelate was synthesized by a sol-gel method at low temperature (500 °C) and its interfacial electrochemical and electrocatalytic properties in 1 M KOH were investigated in film form on Ni. The oxide film was obtained by painting a slurry of oxide powder and Triton X-100 and subsequent sintering at 400 °C. The cyclic voltammetry of the oxide electrode in 1 M KOH indicated the formation of the diffusion-controlled quasi-reversible Ni(II)-Ni(III) redox couple, prior to the onset of O2 evolution. The oxygen evolution reaction followed approximately first order kinetics in OH- concentration. The Tafel slope was 65 mV decade-1. The electrocatalytic activities of LaNiO3 prepared by different methods have been compared. ©1997 International Association for Hydrogen Energy.
Electrocatalytic properties of La-manganites prepared by low temperature synthesis
(1998) T. Sharma; N.K. Singh; S.K. Tiwari; R.N. Singh
Pure and strontium substituted lanthanum manganites were prepared by a sol-gel route and their electrocatalytic properties, in the form of film electrodes, were studied in relation to O2 evolution. Results showed that the catalytic activity of new oxides in 1 M KOH at 25°C was 25-100 times higher than ones obtained by a conventional ceramic method. The Tafel slopes were ranging 90-114 mV decade-1 and the reaction order in OH- concentration was found to be approximately one. Strontium substitutions have been observed to be greatly beneficial from electrocatalysis stand-point.
Electrocatalytic properties of lanthanum manganite-based oxides obtained by a low temperature method
(1998) A.N. Jain; S.K. Tiwari; R.N. Singh
Pure and Sr-doped lanthanum manganites have been synthesized by a-non-conventional hydroxide solid solution precursor route at 500°C. Their electrochemical and electrocatatytic properties in relation to O2 evolution in KOH solutions have been investigated as film electrodes by cyclic voltammetry, AC impedance and Tafel polarization techniques. The oxide powders have been used to obtain catalytic films on the nickel supports by painting with a slurry of the oxide followed by sintering at 400°C. The electrochemically active area vis-a- vis the electrocatalytic activity of the oxides increases considerably with increasing Sr-content from 0.1 to 0.4 mole in the perovskite lattice. Both, the apparent as well as the true, catalytic activities of the oxide are found to be many times higher than those of the samples prepared by conventional ceramic methods. The electrolytic evolution of O2 follows approximately first order kinetics in OH- concentration. The Tafel slopes are in the range 90-140 mV decade-1.
Electrocatalytic properties of lanthanum manganites obtained by a novel malic acid-aided route
(Elsevier Ltd, 1998) N.K. Singh; S.K. Tiwari; R.N. Singh
Electrochemical properties of lanthanum manganite and its substituted derivatives for oxygen evolution in KOH solutions were studied by cyclic voltammetry, AC impedance and Tafel polarization techniques. The oxides were obtained by a sol-gel route, using malic acid as precursor. The catalytic activity of LaMnO3 electrode, prepared by this new method, was found to be approximately 15 times higher than the one obtained by ceramic method. The introduction of 0.2-0.4 mole Sr in the perovskite lattice further improved the activity of the catalyst. However, other Sr-substitutions (0.1 and 0.6 mole) appeared to be less beneficial. 0.2 mole Pb-substitution showed to be highly detrimental from the electrocatalysis point of view. The oxygen evolution reaction followed a first-order kinetics with respect to OH- concentration. The Tafel slope value was 108 ± 5 mV decade-1. © 1998 International Association for Hydrogen Energy.
Electrocatalytic properties of spinel-type MnxFe3-x O4 synthesized below 100°C for oxygen evolution in KOH solutions
(Royal Society of Chemistry, 1996) N.K. Singh; S.K. Tiwari; K.L. Anitha; R.N. Singh
Some spinel ferrites (MnxFe3-xO4; x = 0, 0.5, 1.0, 1.5) have been synthesized at 70°C by the method of precipitation, for electrochemical characterization as oxygen anodes. The electrodes were prepared as films on a nickel substrate by painting with an oxide-slurry, followed by sintering at 400°C. The electrocatalytic activity for O2 evolution was found to be a maximum with the MnFe2O4 electrode. Based on the observed current density at 0.625 V, the activity of MnFe2O4 was 20 times higher than that of Fe3O4. The reaction followed approximately second-order kinetics in [OH-] at the pure and manganese-substituted ferrite film electrodes. The Tafel slope values were ca. RT/F on Fe3O4 and Mn0.5Fe2.5O4 and ca. 2RT/3F on MnFe2O4 and MH1.5Fe1.5O4. Based on the electrode kinetic results, a reaction mechanism for oxygen evolution is suggested.
Evaluation of antimicrobial activity and bronchodialator effect of a polyherbal drug-Shrishadi
(Asian Pacific Tropical Biomedicine Press, 2012) Divya Kumari Kajaria; Mayank Gangwar; Dharmendra Kumar; Amit Kumar Sharma; Ragini Tilak; Gopal Nath; Yamini Bhusan Tripathi; J.S. Tripathi; S.K. Tiwari
Objective: To investigate antimicrobial and bronchodialator effect of hydroalcholic extract of polyherbal drug Shirishadi containing Shirisha (Albezzia lebbeck), Nagarmotha (Cyprus rotandus) & Kantakari (Solanum xanthocarpum). Methods: Antimicrobial activity was evaluated by disc diffusion method and MIC, MBC, MFC were calculated by micro dilution method. Hydroalcholic extract of this preparation was investigated for its phytochemical analysis, phenol and flavonoid were determined by spectrophotometric method and in vivo bronchodilator effect was analysed by convulsion time. Results: The phytochemical tests revealed presence of alkaloids, anthraquinones, carbohydrates, flavonoids, saponins and tannins. The antimicrobial result showed the MIC of 6.25 mg/mL against Staphylococcus aureus and 12.5 mg/mL for Escherichia coli and 12.5 mg/mL against remaining bacteria tested, with strong antifungal activity. The maximum inhibition zone is found against Pseudomonas aeruginosa with MIC 16 mg/mL. Drug showed significant bronchodilator effect with 27.86% & 36.13% increase in preconvulsion time of guinea pigs pretreated with 100 & 200 mg/kg body weight of extract. Conclusions: The study reveals that the extracts possess antibacterial activity and antifungal activity in a dose dependent manner. This antimicrobial property may be due to presence of several saponins, further studies are highly needed for the drug development. © 2012 Asian Pacific Tropical Biomedical Magazine.
Fluoride contamination in southern block of Sonbhadra district, Uttar Pradesh, India
(India Meteorological Department, 2020) Ravi Shanker Patel; S.K. Tiwari; S.B. Dwivedi; D. Mohan
[No abstract available]
Groundwater Quality assessment using Water Quality Index (WQI) in parts of Varanasi District, Uttar Pradesh, India
(Geological Society of India, 2018) Abhishek Kumar Chaurasia; H.K. Pandey; S.K. Tiwari; Ram Prakash; Prashant Pandey; Arjun Ram
The water quality index (WQI) is an important tool to determine the drinking water quality in urban, rural and industrial area. WQI is defined as an index reflecting the composite influence of different water quality parameters which is considered and taken for calculation of water quality index. In the present study, sixteen groundwater samples were collected from the southern portion of the Varanasi district, Uttar Pradesh, India, during the pre monsoon period of May, 2015. The twenty two water quality parameters have been considered for the calculation of water quality index viz. pH, electrical conductivity (EC), total hardness (TH), total dissolved solid (TDS), alkalinity, sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), nitrates (NO3"), bicarbonate (HCO3 –), chlorides (Cl–), sulphates (SO4 –), fluorides (F–), chromium (Cr), zinc (Zn), copper (Cu), manganese (Mn), iron (Fe), nickel (Ni), lead (Pb) and cadmium (Cd). The Bureau of Indian Standard (BIS, 2012) has been considered to assess the suitability of groundwater for drinking purposes and for the calculation of WQI. Correlation study between various physicochemical properties also reveals significant negative relationships. The current study shows that ~20% area is falling under the non suitable for drinking water category and rest is falling under good, moderate, poor, very poor as per the WQI classification. The present study is helpful in proper planning and management of available water resource for drinking purpose. © 2018, Geological Society of India.
Groundwater quality assessment using water quality index (WQI) under GIS framework
(Springer Science and Business Media Deutschland GmbH, 2021) Arjun Ram; S.K. Tiwari; H.K. Pandey; Abhishek Kumar Chaurasia; Supriya Singh; Y.V. Singh
Groundwater is an important source for drinking water supply in hard rock terrain of Bundelkhand massif particularly in District Mahoba, Uttar Pradesh, India. An attempt has been made in this work to understand the suitability of groundwater for human consumption. The parameters like pH, electrical conductivity, total dissolved solids, alkalinity, total hardness, calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, fluoride, nitrate, copper, manganese, silver, zinc, iron and nickel were analysed to estimate the groundwater quality. The water quality index (WQI) has been applied to categorize the water quality viz: excellent, good, poor, etc. which is quite useful to infer the quality of water to the people and policy makers in the concerned area. The WQI in the study area ranges from 4.75 to 115.93. The overall WQI in the study area indicates that the groundwater is safe and potable except few localized pockets in Charkhari and Jaitpur Blocks. The Hill-Piper Trilinear diagram reveals that the groundwater of the study area falls under Na+-Cl−, mixed Ca2+-Mg2+-Cl− and Ca2+-HCO3- types. The granite-gneiss contains orthoclase feldspar and biotite minerals which after weathering yields bicarbonate and chloride rich groundwater. The correlation matrix has been created and analysed to observe their significant impetus on the assessment of groundwater quality. The current study suggests that the groundwater of the area under deteriorated water quality needs treatment before consumption and also to be protected from the perils of geogenic/anthropogenic contamination. © 2021, The Author(s).
Groundwater resource assessment of an alluvial aquifer in parts of Varanasi and Sant Ravidas Nagar Districts, Uttar Pradesh, India using GRE-2015
(IOP Publishing Ltd, 2020) Abhishek Kumar Chaurasia; H.K. Pandey; S.K. Tiwari
The importance of groundwater in India can be realized from the fact that the 85% of rural drinking water supply is dependent on groundwater. There has been paradigm shift from surface to ground water in view of poor quality and reduction in river flow/discharge in the recent past. The concept of micro and sustainable irrigation may be achieved efficiently through groundwater. Therefore, the groundwater resource assessment is essential to make the development plan for meeting out the drinking and irrigation demand for any groundwater unit. An attempt has been made to evaluate the groundwater resource using the latest Ground Water Resource Estimation (GRE-15) of an area that has gone through extensive irrigation using groundwater so that the groundwater stress areas can be sustainably managed. The present research is based on the Groundwater Resource Estimation methodology- 2015 to evaluate the groundwater availability and the stress conditions occurring in the study area. The stage of groundwater development inferred after the study shows that Araziline block of Varanasi and Bhadohi block of Sant Ravidas Nagar district of Uttar Pradesh are falling under the critical category while Sevapuri block of Varanasi district of Uttar Pradesh falls under the semi-critical category. The current estimation warrants the immediate need for proper management of groundwater resources. © 2020 Institute of Physics Publishing. All rights reserved.