Browsing by Author "T. Singh"

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1,3,4-Thiadiazoles as potential EP additives - a tribological evaluation using a four-ball test
(1995) A. Bhattacharya; T. Singh; V.K. Verma; N. Prasad
This paper reports a comparative study of the wear-reducing efficiency and extreme pressure properties of 0.5% ( w v) admixtures of paraffin oil and 2-amino-5-arylamino-1,3,4-thiadiazole additives and a commercial sulphur-phosphorus additive in a four-ball test. 2-Amino-5-p-Cl-phenylamino-1,3,4-thiadiazole additive shows excellent EP properties as is evident from the surface smoothness of SEM micrographs. The tribochemistry of the wear-scar surface has been investigated by the auger electron spectroscopy (AES) technique. © 1995.
An interacting two-fluid scenario for dark energy in anisotropic cosmological model
(2013) T. Singh; R. Chaubey
The open anisotropic cosmological model of the early Universe is considered. We study the evolution of the dark energy parameter within anisotropic Bianchi type-V cosmological model filled with barotropic fluid and dark energy. The solutions have been obtained for power law and exponential forms of the expansion parameter. (They correspond to constant deceleration parameter in general relativity.) For large time (i.e., t → ∞), the models tend asymptotically to an isotropic Friedmann-Robertson-Walker cosmological model under certain conditions. © 2013 Published by NRC Research Press.
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.
Aspects of nonflat FRW bouncing models with quadratic equation of state
(World Scientific Publishing Co. Pte Ltd, 2018) Ashutosh Singh; Rakesh Raushan; R. Chaubey; T. Singh
In this paper, we investigate the possibility of a nonsingular model of universe in the framework of general relativity in nonflat FRW geometries with quadratic equation of state and bulk viscosity. We study whether a nonsingular bounce requires violation of energy conditions. We discuss the thermodynamical aspects of the resulting models with equilibrium description. In particular, we discuss the validity of the generalized second law of thermodynamics for resulting cosmologies. © 2018 World Scientific Publishing Company.
Assessment of awareness regarding health hazards of plastic chemicals and their warning label among a sample population of Varanasi City: A cross-sectional study
(Wolters Kluwer Medknow Publications, 2021) Parul Sharma; Priyanka Bhagat; M. Mandal; T. Singh
Background: Plastic containers are widely used to store and serve edibles. In the production of some types of plastic, chemicals such as bisphenol A (BPA) and bisphenol S (BPS) are used. These chemicals leach from the plastic containers into the edibles, get access into the biological systems, and cause a toxic impact on health. Aim: This cross-sectional survey was planned to assess the usage of food contact plastic and awareness regarding the health hazards of plastic chemicals and warning labels on plastic items among a sample population of Varanasi city. Materials and Methods: Data were collected by interviewing the 556 adult participants, using a prevalidated structured questionnaire. Chi-square test was used to test the association and P < 0.05 was considered as significant. Results: Most of the participants were found to be following routine practices during cooking and storage of edibles which may expose them to BPA and BPS through the gut. Although many participants were aware that plastic may contain some type of chemicals which may enter the human body and harm human health in some way, they lacked precise knowledge regarding warning label like 'BPA free plastic' 'plastic containing BPA' and 'food grade plastic.' Furthermore, none of the participants could recognize the 'resin identification codes' correctly. Conclusion: Most of the participants had only elementary awareness of health risk of plastic usage. A significant number of participants lacked crucial information that can help them to make healthy choices as a consumer and use safe alternatives of plastic. © 2021 Journal of Pharmacy and Bioallied Sciences. All rights reserved.
Bianchi type I cosmological model with a cosmological constant (Λ) in creation-field cosmology
(Maik Nauka Publishing / Springer SBM, 2015) R. Chaubey; A.K. Shukla; A. Singh; T. Singh
Solutions of Einstein’s field equations with a cosmological constant Λ in the presence of a creation field have been obtained for Bianchi type I cosmological models in the Hoyle-Narlikar creation field theory. The cosmological parameters are calculated. We examine the nature of the creation field and the cosmological constant which dominate at the early stage of the universe, but they do not survive for a long time and finally tend to zero at large cosmic times. © 2015, Pleiades Publishing, Ltd.
Bounce conditions for FRW models in modified gravity theories
(Springer Verlag, 2015) T. Singh; R. Chaubey; Ashutosh Singh
In this paper, we have derived the minimal conditions for a bounce to occur in FRW cosmologies for the theories like Hoyle-Narlikar creation field theory, Lyra geometry, Brans-Dicke theory, general class of Scalar-Tensor theories, Einstein’s theory with variable cosmological term, with bulk viscosity and Finslerian cosmology. We derive the model-independent minimal necessary conditions for non-singular bounce and show that there is an open temporal region surrounding the bounce over which the strong energy condition (SEC) must be violated. Null energy condition is also violated in some of the modified gravity theories. © 2015, Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg.
Bounce conditions in Kantowski-Sachs and Bianchi cosmologies in modified gravity theories
(World Scientific Publishing Co. Pte Ltd, 2015) T. Singh; R. Chaubey; Ashutosh Singh
Many cosmological scenarios envisage either a bounce of the universe at early times, or a collapse locally to form a black hole which re-expands into a new expanding universe region. Energy conditions preclude this phenomena for ordinary matter in general relativistic universe, but scalar or other types of fields can violate some of these conditions, and so can, possibly, provide conditions for a bouncing universe. In this paper, we have investigated the necessary conditions for a bounce in Kantowski-Sachs (KS) and Bianchi type models in some modified theories of gravity like Hoyle-Narlikar creation field theory, Lyra geometry, general class of scalar-tensor theories, Einstein's theory with variable cosmological term. © 2015 World Scientific Publishing Company.
Bouncing cosmologies in Brans-Dicke theory
(Canadian Science Publishing, 2016) T. Singh; R. Chaubey; Ashutosh Singh
In this paper it is shown that in Brans-Dicke theory, if one considers a non-minimal coupling between the matter and scalar field, can give rise to a bouncing universe (i.e., an expanding universe preceded by a contracting universe). Two examples of such universes have been considered in a spatially flat Friedmann-Robertson-Walker universe and their physical properties have been studied. © 2016 Published by NRC Research Press.
Bouncing cosmologies with viscous fluids
(Springer Netherlands, 2016) T. Singh; R. Chaubey; Ashutosh Singh
The bounce in viscous fluid cosmology with inhomogeneous viscous fluids in Friedman-Robertson-Walker (FRW) space-time has been investigated. Different forms for the scale factor have been considered. The general features of the fluids which realize them and the possibility to have an acceleration after the bounce have been discussed. © 2016, Springer Science+Business Media Dordrecht.
Dark Energy with Generalized Equation of State in Bianchi Type-I Cosmological Model
(2012) T. Singh; R. Chaubey
Dark energy with the usually used equation of state p=γρ, where γ=const < 0 is hydrodynamically unstable. To overcome this drawback we consider the cosmology of a perfect fluid with a linear equation of state of a more general form p=α(ρ-ρ0), where the constants α and ρ0 are free parameters. The anisotropic Bianchi type-I cosmological model filled with dark energy has been considered. A generalized equation of state for the dark energy component of the universe has been used. The exact solutions to the corresponding Einstein field equations and the statefinder diagnostic pair i. e. {r,s} parameters have been obtained in three interesting cases (i) when ρΛ > 0 and A > 0 (ii) when ρΛ > 0 and A > 0 and (iii) when ρΛ < 0 and A > 0 at the singularities i. e. t→0 and t→±∞. © 2011 Springer Science+Business Media, LLC.
Estimation and correlation of serum folic acid levels in spina bifida babies and their mothers
(2008) D. Gupta; A. Pandey; A. Gangopadhyay; S. Prasad; T. Singh; H. Khanna; V. Upadhyaya
Spina bifida is a common neural tube defect. The relative deficiency of folic acid (FA) in mother during periconceptional period is an important factor. We measured the serum FA levels in spina bifida babies and their mothers and compared the result with the FA level in normal babies. The blood samples were collected at the time of admission to hospital. Enquiry made about the age, sex, and birth order, problem in siblings and FA supplementation and detailed examination done to access the severity of the problem. Folic acid estimation was done by enzyme-linked immunosorbent assay method. Antenatal FA supplementation was found in 40% of cases and 80% of control group. In the study group, the mean FA level in babies and mothers of FA supplemented group was 21.73 ± 5.64 ng/dl and 15.02 ± 3.02 ng/dl and in non-supplemented group were 7.41 ± 1.48 ng/dl and 4.12 ± 0.81 ng/dl, respectively. In control group mean FA level in babies and mothers of FA supplemented group were 16.88 ± 3.2 ng/dl and 14.70 ± 2.30 ng/dl and in nonsupplemented group were 14.33 ± 1.74 ng/dl and 10.75 ± 1.34 ng/dl, respectively. The serum FA levels in spina bifida babies as well as in their mothers were significantly low as compared to control group. This study suggests that the low serum FA levels in a lady at the time of pregnancy may be a causative factor in the pathogenesis of spina bifida and low levels in affected babies.
Evaluation of 2,4-dithiomalonamides as extreme pressure additives in the four-ball test
(1990) T. Singh; R. Singh; V.K. Verma
Four-ball tests using 12.7 mm diameter steel bearing balls were conducted to evaluate the load-carrying and extreme pressure properties of admixtures of paraffin oil with 1,5-diaryl-2-4-dithiomalonamides and a sulphur-phosphorus commercial additive (0.5 per cent wt/vol.). 1,5-Di-p-methoxyphenyl-2,4-dithiomalonamide exhibiting wear scar diameter and friction coefficient values of 0.58 mm and 0.058 at 100 kgf (ISL) and 2.18 mm and 0.077 at 500 kgf as compared to the values of 2.05 mm and 0.022 at 56 kgf (ISL) and 2.73 mm and 0.43 at 100 kgf for paraffin oil appeared to be most effective. The surface topography of the wear scars were examined by scanning electron microscope.
General class of Bianchi cosmological models with Λ in creation-field cosmology
(Kluwer Academic Publishers, 2014) R. Chaubey; A.K. Shukla; Ashutosh Singh; T. Singh
The solutions of Einstein's equations with cosmological constant (Λ) in the presence of a creation field have been obtained for general class of anisotropic cosmological models. We have obtained the cosmological solutions for two different scenarios of average scale factor. In first case, we have discussed three different types of physically viable cosmological solutions of average scale factor for the general class of Bianchi cosmological models by using a special law for deceleration parameter which is linear in time with a negative slope. In second case, we have discussed another three different forms of cosmological solutions by using the average scale factor in three different scenarios like Intermediate scenario, Logamediate scenario and Emergent scenario. All physical parameters are calculated and discussed in each physical viable cosmological model. We examine the nature of creation field and cosmological constant is dominated the early Universe but they do not survive for long time and finally tends to zero for large cosmic time t. We have also discussed the all energy conditions in each cases. © 2014 Springer Science+Business Media Dordrecht.
Induced resistance and control of charcoal rot in Cicer arietinum (chickpea) by Pseudomonas fluorescens
(2001) A.K. Srivastava; T. Singh; T.K. Jana; D.K. Arora
Pseudomonas fluorescens isolate 4-92 induced systemic resistance against charcoal rot disease in chickpea (Cicer arietinum L.) caused by Macrophomina phaseolina (Tassi) Goidanich. Time-course accumulation of pathogenesis-related (PR) proteins (chitinases and glucanases) in chickpea plants inoculated with P. fluorescens was significantly (P = 0.05) higher than in control plants. The level of chitinases and glucanases increased by 6.6- to 7-fold up to 4 days postinoculation; thereafter, little decrease in the activity of PR proteins was observed. Root-colonizing populations of P. fluorescens were at a maximum 2 days after transplantation at different inoculum concentrations, and decreased over time. Inoculation of root tips of chickpea by P. fluorescens, 2,6-dichloroisonicotinic acid, and o-acetylsalicylic acid induced systemic resistance against charcoal rot. Disease was 33 to 55.5% higher in control plants than in plants inoculated with chemical inducers or P. fluorescens. Single treatment of plants with P. fluorescens increased disease resistance by 33%, whereas combined application of P. fluorescens with either of the chemical inducers was most effective in inducing the resistance by 2- to 2.25-fold. The time-course study shows that an interval of at least 2 days was required between induction treatment and challenge inoculation. Biocontrol efficacy of P. fluorescens against charcoal rot disease in chickpea was demonstrated under greenhouse conditions.
K-essence cosmologies in Kantowski-Sachs and Bianchi space-times
(Canadian Science Publishing, 2015) T. Singh; R. Chaubey; Ashutosh Singh
We investigate Kantowski-Sachs, locally rotationally symmetric Bianchi-I and Bianchi-III cosmology with k-essence and found a set of models that dissipate the initial anisotropy. We obtain the conditions leading to a regular bounce of the average geometry. We show that the linear k-field and polynomial kinetic function models evolve asymptotically to Friedmann-Robertson-Walker cosmologies. For linear k-essence we find the general solution in these cosmologies, when the k-field is driven by an inverse scalar potential. © 2015 Published by NRC Research Press.
Kantowski-Sachs and Bianchi type models with a general non-canonical scalar field
(Maik Nauka Publishing / Springer SBM, 2017) T. Singh; R. Chaubey; Ashutosh Singh
The paper deals with spatially homogeneous and anisotropic Kantowski-Sachs and Bianchi universes with a general non-canonical scalar field with the Lagrangian L = F(X) − Ω(ϕ), where X=12ϕiϕi. We discuss a general non-canonical scalar field in three different cosmologies: (i) cosmology with a constant potential, Ω(ϕ) = Ω0 = const, (ii) cosmology with a constant equation-of-state parameter, i.e., γϕ = const, and (iii) cosmology with a constant speed of sound, i.e., cs 2 = const. For a constant potential, we have shown that the k-essence Lagrangian and the Lagrangian of the present model are equivalent. Dissipation of anisotropy, when the universe is filled with a general non-canonical scalar field, is investigated. The existence of an average bounce in Kantowski-Sachs and locally rotationally symmetric Bianchi-I and Bianchi-III models is discussed in detail. © 2017, Pleiades Publishing, Ltd.
Locally rotationally symmetric Bianchi type-I cosmological model with dynamical Λ and G in f(R) gravity
(Springer, 2019) Rakesh Raushan; A.K. Shukla; R. Chaubey; T. Singh
In this paper, we have studied the locally rotationally symmetric (LRS) Bianchi type-I cosmological model filled with a bulk viscous cosmological fluid in f(R) gravity in the presence of time-varying gravitational and cosmological constant. We have used the power-law and intermediate scenario for scale factor to obtain the solution of the field equations. The evolution of temperature of a viscous Universe is also analysed. © 2019, Indian Academy of Sciences.
Motility and chemotactic response of Pseudomonas fluorescens toward chemoattractants present in the exudate of Macrophomina phaseolina
(Elsevier GmbH, 2001) T. Singh; D.K. Arora
Pseudomonas fluorescens strains (LAM1-hydrophilic) and (LAM2-hydrophobic) showed positive chemotaxis towards attractants (sugars, amino acids, polyols and organic acids) present in the exudate of Macrophomina phaseolina (a soil-borne plant pathogenic fungus). The varied response of motility traits such as speed, rate of change in direction (RCDI) and net to gross displacement ratio (NGDR) was observed for different chemoattractants. Swimming speed of the strains was highest in 10-fold diluted exudate or 100-1000 μM strength of different attractants, but further dilutions significantly decreased the swimming speed (P = 0.05). Chemotactic response of P. fluorescens was positively correlated with swimming speed (P = 0.05; r = 0.76). Relative to control, the RCDI values decreased 1.5-fold in amino acids or sugars, and 1.2-fold in polyols or organic acids. With increase in swimming speed, the NGDR of both strains also increased, but the RCDI decreased. Both hydrophilic and hydrophobic strains did not show significant differences in their motility traits. The results demonstrate that M. phaseolina exudate contains chemical attractants that serve as signal for flagellar motility of P. fluorescens. Motile P. fluorescens strains thus may consume fungal exudate as nutrients, and thus spores could offer a niche for these bacteria in soil.
On stationary axially symmetric Einsteinâ Maxwell scalar and Bransâ Dickeâ Maxwell fields
(1981) T. Singh; L.N. Rai
A particular type of exact solutions of Einsteinâ Maxwell massless scalar field equations corresponding to stationary axially symmetric fields is presented here. The solutions are linear combinations of static fields with constant coefficients. Further, by a proper choice of conformal transformation the solutions have been transformed to the Bransâ Dicke fields coupled with sourceâ free electromagnetic fields. Finally these solutions have been transformed to a general form through unit transformations. © 1981, American Institute of Physics. All rights reserved.