Browsing by Author "R.K. Singh"

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A generalised shell model of lattice dynamics
(1972) R.K. Singh
A generalised shell model is presented to study the lattice dynamics of ionic crystals by incorporating the electron shell deformation and zero-point vibration effects in the shell model. The model makes nearest approach to the quantum mechanical shell model of Sinha and seems to be eminently suitable for the purpose. © 1972.
A preliminary study on the effect of Azadirachta indica on bronchial smooth muscles and mast cells
(Natural Remedies Private Limited, 2003) S.B. Acharya; S.U. Yanpallewar; R.K. Singh
Objective: The present study was designed to assess the protective effect of Azadirachta indica on bronchial smooth muscles and mast cells. Methods: Azadirachta indica (200 mg/kg p.o.) leaf juice was administered to animals and its protective effect was determined on histamine aerosol induced bronchospasm in guinea pigs, comp 48/80 induced mast cell degranulation and active anaphylaxis in rats. Results: A significant protection against histamine induced bronchospasm in guinea pigs was observed. There was 63% delay in onset of dyspnoea in A. indica treated animals against that of 16% in control animals. A. indica neither could prevent mast cell degranulation nor could protect against active anaphylaxis. Conclusion: The results of the present preliminary study reveal that A. indica has bronchoprotective role. Moreover, it also suggests that mechanisms other than that associated with mast cell degranulation or active anaphylaxis are possibly involved in bronchoprotective role of A.indica.
Absorption and velocity of acoustical waves in binary solutions of poly (ethylene glycol) and water
(2008) R.K. Singh; M.P. Singh; R.P. Singh
The velocity and absorption of ultrasonic waves have been measured in aqueous solutions of poly (ethylene glycol). The velocity of ultrasonic waves was obtained in the frequency range 1MHz-12MHz over a wide range of temperature. The concentration (by weight) ranged from 1% to 10% of poly (ethylene glycol) in water. The shear viscosity was also measured. Measurements were carried out in the temperatures range 35 °C to 65 °C. It was observed that velocity of ultrasonic wave increases with temperature at a given concentration, while as concentration is increased at a given temperature, velocity was found to increase. The shear viscosity and density decreased with temperature.
Acoustic wave propagation in barium monochalcogenides in the B1 phase
(2009) R.K. Singh; Rishi Pal Singh; M.P. Singh; S.K. Chaurasia
Temperature dependence of ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss have been studied in (NaCl-type) barium monochalcogenides [BaX, X = S, Se, Te], in the temperature range 50-500 K; for longitudinal and shear modes of propagation along 〈100〉, 〈110〉, 〈111〉 directions. Second and third order elastic constants have been evaluated using electrostatic and Born repulsive potentials and taking interactions up to next nearest neighbours. Gruneisen parameters, nonlinearity constants, nonlinearity constants ratios and viscous drag due to screw and edge dislocations have also been evaluated for longitudinal and shear waves at 300 K. In the present investigation, it has been found that phonon-phonon interaction is the dominant cause for ultrasonic attenuation. The possible implications of results have been discussed. © 2009 Pleiades Publishing, Ltd.
Acoustical characterization of nanostructured metal
(2008) R.K. Singh; R.P. Singh; M.P. Singh
Ultrasonic attenuation due to phonon-phonon interaction, thermoelastic loss and dislocation damping arising from screw and edge dislocations has been evaluated in nanocrystalline copper (13 nm) in the temperature range 50-500K, and size-dependent attenuation at a constant temperature for longitudinal and shear modes of propagation. Second and third order elastic constants have been obtained, taking the nearest neighbor distance and the hardness parameter as input data. SOEC and TOEC (obtained at different temperatures) have been used to obtain Grüneisen parameters and nonlinearity parameters, which in turn have been used to evaluate α/f2 for longitudinal and shear waves. Results have been discussed, and compared with available experimental values. It has been found that α/f2 increases with temperature and a significant contribution to the total attenuation occurs due to scattering from grain boundaries, and ultrasonic attenuation due to thermoelastic loss is negligible compared to phonon-phonon interaction, establishing that the major part of energy from the sound wave is removed owing to the interaction of acoustic phonons with thermal phonons (lattice vibrations). © World Scientific Publishing Company.
Acoustical dissipation due to phonon-phonon interaction, thermoelastic loss and dislocation damping in MnO and CoO
(2008) R.P. Singh; M.P. Singh; R.K. Singh
Temperature dependent ultrasonic attenuation due to phonon-phonon interaction, thermoelastic mechanism and dislocation damping due to screw and edge dislocations have been evaluated in MnO and CoO in fcc (B1- type) phase, in a wide temperature range 50 ≤ T ≤ 500 K for longitudinal and shear modes of propagation along three crystallographic directions viz. 〈100〉, 〈110〉 and 〈111〉. Electrostatic and Born-Mayer potentials were used to obtain second and third order elastic moduli at different temperatures taking interactions up to next nearest neighbours. Second and third order elastic moduli obtained at different temperatures have been used to obtain gruneisen parameters and non-linearity parameters which in turn were used to evaluate attenuation coefficient over frequency square viz. (α/f 2) for longitudinal and shear waves. Specific heat (as function of Debye temperature), hardness parameter and lattice parameter have been used as input data. Results have been discussed and it has been found that thermoelastic mechanism has negligible contribution to the total attenuation compared to phonon-phonon interaction.
Acoustical investigations of uranium chalcogenides
(2009) R.K. Singh; K.K. Pandey; M.P. Singh; R.P. Singh
Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss was evaluated in uranium chalcogenides viz. UX, X= S, Se, Te in fcc phase in the temperature range 50-600 K for longitudinal and shear waves along the <100>, <110> and <111> directions of propagation. Electrostatic and Born-Mayer repulsive potentials were used to obtain second and third order elastic constants, taking the nearest neighbour distance and hardness parameter as the input data. Second and third order elastic constants (obtained at various temperatures) were used to obtain the Gruneisen parameters and non-linearity or anisotropy parameters, which in turn were used to evaluate the ultrasonic attenuation coefficient over the frequency square due to phonon-phonon interaction, (α/f2)p-p in the Akhiezer regime. It has been found that at lower temperatures α/f2 increases rapidly with temperature, and at higher temperatures the rate of increase becomes small. Contribution to the total attenuation due to thermoelastic loss is negligible in comparison with that of phonon-phonon interaction, i.e. a major part of the energy from the sound wave is removed, due to interaction of acoustic phonons with thermal phonons (lattice vibrations).
Additions to the hyphomycete genus Veronaea as phytoparasitic species
(Elsevier GmbH, 2004) R.N. Kharwar; R.K. Singh
Three new species of Veronaea, V. ficina on Ficus hispida L. (Moraceae), V. grewiicola on Grewia asiatica L. (Tiliaceae), and V. hippocratiae on Hippocratia arborea Willd. (Celastraceae), collected from forests of Nepal and the Terai belt of North-Eastern Uttar Pradesh, India, are described, illustrated and compared with related taxa. © 2004 Elsevier GmbH. All rights reserved.
Adrenocortical response to surgery: changes in plasma cortisol (17-OHCS) levels
(1976) R.K. Singh; P.K. Dhar; J.P.N. Chansouria; K.N. Udupa
[No abstract available]
Adrenocortical response to surgery: changes in urinary corticoids and electrolyte levels
(1976) R.K. Singh; P.K. Dhar; J.P.N. Chansouria; K.N. Udupa
[No abstract available]
Analysis of Genetic Differentiation and Phylogenetic Relationships among Sugarcane Genotypes Differing in Response to Red Rot
(2011) R.K. Singh; M.S. Khan; R. Singh; D.K. Pandey; S. Kumar; S. Lal
The selection of parents is the most crucial step in any breeding programme. A better understanding of genetic diversity among the available genotypes would help the breeder to make better crosses. Advancements of DNA marker techniques in many crops have supplemented the morphological traits with molecular markers to identify the diverse genotypes. The genetic diversity of 30 sugarcane genotypes differing in response to red rot resistance was carried out using simple sequence repeat (SSR) markers. The polymorphism information content (PIC) ranged from 0.216 to 0.813 with an average of 0.525. The highest values (0. 86) of proportion of polymorphic loci (P) and expected heterozygosity (He) were obtained in the susceptible population (S) and moderately resistant population (MR), respectively. FST values between populations ranged from -0.043 to 0.041. However, AMOVA did not show much variation among the groups. Cluster analysis clearly distinguished all the genotypes from each other. The resistant genotypes namely ISH150 and SES594 emerged out to be most distinct genotypes, whereas the rest of the genotypes could be grouped in two broad clusters separating the moderately resistant and susceptible sugarcane genotypes. The clustering pattern was fairly supported by Mantel's test (r=0.894) and high bootstrap value (75.0%). Thus, information given in the present study can be used in genetic resource management as well as in broadening the genetic base of cultivated sugarcane for red rot and selection of suitable parent for generating the mapping population for tagging the red rot resistance gene(s) in sugarcane. copy; 2011 Society for Sugar Research & Promotion.
Anti oxidant potential of Metformin and Pioglitazone in Type 2 Diabetes Mellitus: Beyond their anti glycemic effect
(Elsevier Ltd, 2016) R.K. Singh; B. Gupta; K. Tripathi; S.K. Singh
Objective Insulin sensitizers might influence oxidative stress to improve insulin resistance in diabetes mellitus. The present study was designed with the aim to study the effect of Metformin & Pioglitazone on markers of oxidative stress after 4 weeks of therapy in patients with type 2 diabetes mellitus (Type 2 DM). Research design and methods This was a prospective study with follow up of 4 weeks in patients with Type 2 DM. They were randomized into metformin treated group (N = 20) and Pioglitazone treated group (N = 20) and healthy age-matched control group (N = 20). Data was presented as mean ± S.D. Student "t" test, ANOVA and Pearson correlation co-efficient tests were performed to analyze the parametric data in this study. Results Baseline clinical characteristics of the two study groups were similar. There is a significant difference for Fasting plasma glucose (FPG) and 2h-Post Prandial Plasma Glucose (PPPG) after 30 days of metformin and pioglitazone treatment. Metformin significantly reduced MDA (p = 0.041) and increased SOD (p < 0.001). Pioglitazone significantly reduced MDA (p < 0.001) but failed to raise SOD level (p = 0.132). Mean MDA was 4.57 ± 0.57 μM/L in metformin and 2.91 ± 0.66 μM/L in pioglitazone treatment with a p-value of <0.001. Further, a similar significant difference was obtained for SOD value by metformin and pioglitazone treatment (7.87 ± 0.72 U/ml vs. 6.94 ± 0.53 U/ml; p < 0.001). Conclusion Pioglitazone was superior to Metformin to improve oxidative stress as reflected by reduction in MDA but the antioxidant effect i.e. increase in SOD was seen with metformin only. The differing mechanism of actions of the two drugs on oxidative stress favors co prescription of these drugs for better outcome in improving insulin resistance and diabetic complications. © 2015 Diabetes India.
Anti-inflammatory activity of seed extracts of Pongamia pinnata in rat
(1996) R.K. Singh; B.L. Pandey
Pongamia pinnata is a marsh growing Indian tree. Its seeds are used in febrile and inflammatory diseases in Indian system of medicine. Previous preliminary studies with ethanolic seed extract of this plant had exhibited an anti-inflammatory effect in rat. Different solvent fractionated extracts were evaluated in the present study for anti-inflammatory effect in chemically induced paw inflammation in rats. Anti-inflammatory effects of P. pinnata were best seen against bradykinin and PGE1-induced inflammation. In contrast minimal effects were seen against histamine and 5-HT-induced inflammation. The predominant action of extracts of Pongamia pinnata appears to be a modulation of eicosanoid-events in inflammation.
Anti-inflammatory effect of (+)-pinitol
(2001) R.K. Singh; B.L. Pandey; M. Tripathi; V.B. Pandey
In the carrageenin-induced paw oedema in rats, (+)-pinitol (2.5-10 mg/kg, i.p.), isolated from Abies pindrow leaves, showed a significant anti-inflammatory effect, the highest dose being comparable to phenylbutazone (100 mg/kg, i.p.). Copyright © 2001 Elsevier Science B.V.
Antimicrobial activity of Elaeocarpus sphaericus
(1999) R.K. Singh; Gopal Nath
Antibacterial activity of petroleum ether (PE), benzene (BE), chloroform (CE), acetone (AE) and ethanol (EE) extracts of dried Elaeocarpus sphaericus fruit was investigated against 28 gram-positive and gram-negative bacteria using the disc diffusion and plate dilution methods. The AE fraction showed marked antimicrobial activity against ten organisms. BE was active against Salmonella typhimurium and Morganella morganii, and EE against Plesiomonas shigelloides, Shigella flexnerii and Sh. sonneii. The alkaloids and flavonoids present in the plant appear to be of chemotherapeutic interest.
Antioxidant activity of Cuscuta reflexa stems
(2000) S.B. Yadav; V. Tripathi; R.K. Singh; H.P. Pandey
The in vitro antioxidant activity of Cuscuta reflexa stem extract has been investigated by estimating degree of non-enzymatic hemoglobin glycosylation measured colorimetrically at 440 nm. The ethyl acetate fraction of ethanol extract showed higher activity than the other fractions. The antioxidant activity of extracts are very close and identical in magnitude and comparable to that of standard antioxidant compounds used.
Anxiolytic activity of Indian Abies pindrow Royle leaves in rodents: An experimental study
(2000) V. Kumar; R.K. Singh; A.K. Jaiswal; S.K. Bhattacharya; S.B. Acharya
Putative anxiolytic activity of ethanolic extract of Indian A. pindrow Royle leaf was investigated in rats using various experimental paradigms of anxiety viz. open field exploratory behaviour, elevated plus maze (EPM) and elevated zero maze (EZM) tests. Pilot studies indicated that single dose administration of extract had little to no acute behavioural effects, hence the extract was administered orally at different dose levels once daily for three consecutive days, while lorazepam (LR) (0.5 mg/kg, ip) was administered acutely. Ethanolic extract of A. pindrow (AP) leaves (50 and 100 mg/kg, po) showed significant anxiolytic effects on all the paradigms of anxiety. The results indicate that AP and LR induced a significant increase in open field ambulation and slight increase in rearings and activity in center, whereas grooming and faecal droppings remain unchanged. In EPM, significant augmentation of open arm entries, and time spent on open arms was noted in AP treated rats. In EZM test, significant increase in time spent on open arms and entries in open arms was observed, whereas slight increase in head dips and stretched attend postures was also observed. The AP extract showed consistent and significant anxiolytic activity in all the tests. The effects induced by ethanolic extract of AP were less marked than those of lorazepam were.
Application of bacterial endophytes as bioinoculant enhances germination, seedling growth and yield of maize (Zea mays L.)
(Range Management Society of India, 2013) N.P. Singh; R.K. Singh; J.P. Shahi; H.K. Jaiswal; T. Singh
Ten endophytic bacteria isolated from maize plants at farmer fields were characterized for their endophytic association and various biochemical activities such as production of phytohormones, siderophore and phosphate solubilization. All the selected isolates produced indole acetic acid. However, four isolates (BHU3, BHU8, BHU9 and BHU10) have ability for phosphate solubilization. Siderophore production was shown by six isolates (BHU1, BHU2, BHU3, BHU5, BHU8 and BHU10). Activates of endophytic bacterial isolates under field conditions indicated significant increase in seed germination, chlorophyll content, cob length, plant height, test weight, grain yield and harvest index over control. Isolates BHU3, BHU8 and BHU10 performed relatively better than the other isolates.
Arthrobotrys oligospora-mediated biological control of diseases of tomato (Lycopersicon esculentum Mill.) caused by Meloidogyne incognita and Rhizoctonia solani
(2013) U.B. Singh; A. Sahu; N. Sahu; R.K. Singh; S. Renu; D.P. Singh; M.C. Manna; B.K. Sarma; H.B. Singh; K.P. Singh
Aims: To study the biocontrol potential of nematode-trapping fungus Arthrobotrys oligospora in protecting tomato (Lycopersicon esculentum Mill.) against Meloidogyne incognita and Rhizoctonia solani under greenhouse and field conditions. Methods and Results: Five isolates of the nematode-trapping fungus Arthrobotrys oligospora isolated from different parts of India were tested against Meloidogyne incognita and Rhizoctonia solani in tomato (Lycopersicon esculentum Mill.) plants grown under greenhouse and field conditions. Arthrobotrys oligospora-treated plants showed enhanced growth in terms of shoot and root length and biomass, chlorophyll and total phenolic content and high phenylalanine ammonia lyase activity in comparison with M. incognita- and R. solani-inoculated plants. Biochemical profiling when correlated with disease severity and intensity in A. oligospora-treated and untreated plants indicate that A. oligospora VNS-1 offered significant disease reduction in terms of number of root galls, seedling mortality, lesion length, disease index, better plant growth and fruit yield as compared to M. incognita- and R. solani-challenged plants. Conclusion: The result established that A. oligospora VNS-1 has the potential to provide bioprotection agents against M. incognita and R. solani. Significance and Impact of the Study: Arthrobotrys oligospora can be a better environment friendly option and can be incorporated in the integrated disease management module of crop protection. Application of A. oligospora not only helps in the control of nematodes but also increases plant growth and enhances nutritional value of tomato fruits. Thus, it proves to be an excellent biocontrol as well as plant growth promoting agent. © 2012 The Society for Applied Microbiology.
Bio-efficacy and selectivity of sulfosulfuron and metribuzin before and after irrigation in wheat (Triticum aestivum) under zero-tillage system
(2009) R.K. Singh; S.K. Verma; Rajvir Sharma; S.B. Singh
A field experiment was conducted during winter(rabi) season of 2003-04 and 2004-05 at agronomy reasearch farm, BHU, Varanasi, to study the bio-efficacy and selectivity of sulfosulfuron and metribuzin before and after irrigation in wheat (Triticum aestivum L. emend. Fiori & Paol.) underzerotillage system. Eight ween control treatments, viz metribuzin 0.21 kg/ha before first irrigation (BFI), Metribuzin 0.21 kg/ha after first irrigation (AFI), sulfosulfuron 0.025 kg/ha BFI sulfosulfuron 0.025 kg/ha AFI, isoproturon +2, 4-D0.75+0.5 kg/ha AFI, 1 hand weeding at 30 days after sowing (DAS), 2 were tested in randomized block design with 3 replications. Sulfosulfuron (AFI) significantly reduced weed density, dry weight and NPK depletion by weeds with maximum weed control efficiency (79.4%) and improved the NPK uptake by crop which cause significant impact on crop growth and yield attributes which resulted higher grain yield (3.24 and 3.53 tonnes/ha), being at par with that of one hand weeding at 30 days after sowing. Isoproturon + 2, 4-D (AFI) significantly reduced density and dry weight of weeds over metribuzin (BFI) and sulfosulfuron (BFI) and it was at par with metribuzin (AFI) and 1 hand weeding. Among the herbicidal treatments, maximum net returns (Rs 7564 and 9165/ha) and benefit: cost ration (1.54 and 1.63) were recorded under isoproturon + 2, 4-D (AFI). Hand weeding twice at 30 and 45 DAS recorded significantly higher yield attributes, grain yield, nutrients uptake with maximum weed control efficiency, net returns and benefits : cost ration over all other weed control treatments.