Browsing by Author "D. Kumar"

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A Novel Transformation: Based on Inverse Trigonometric Lindley Distribution
(Gnedenko Forum, 2022) D. Kumar; P.K. Chaurasia; P. Kumar; A. Chaurasia
As we see that the present era is directly depending upon various kinds of machines. In other words, we can say that we are fully surrounded by machines. Machines are assembled with many components and each component has its own importance. For proper functioning of a machine, these components should be up to date. Therefore, for smooth functioning, we have to make replacement of the component before its failure. In this present paper, we propose a new transformation which is purely based on inverse trigonometry with lindley distribution for the first time and so, named "Inverse Trigonometric Lindley Distribution". It find its various properties like survival function, hazard rate function, moments, conditional moments, order statistics, entropy measurement etc. Maximum likelihood estimator have also considered for estimation of parameter. To know the paternal behavior of the model, different real datasets have been considered. To understand the behavior of estimators at the long run, simulation study is being performed in detail. © 2022 Gnedenko Forum. All Rights Reserved.
Amorphous to crystalline phase transition in glassy Se65Te20Ag15 alloy
(2009) R.S. Tiwari; D. Kumar; N. Mehta
In the present work, the amorphous to crystalline phase transition of chalcogenide glass Se65Te20Ag15 has been studied using differential scanning calorimetric (DSC) measurements. The heating rate dependence of crystallization peaks has been used for the determination of activation energies of glass transition (Eg) and crystallization (Ec). Different non-isothermal methods have been used for this purpose. Other useful kinetic parameters such as the order parameter (n), the numerical factor of crystallization mechanism (m) and the frequency factor (Ko) of the rate constant (K) have been also determined.
Antinormal Composition Operators on the L 2-Space of an Atomic Measure Space
(Springer New York LLC, 2019) D. Kumar; H. Chandra
Let L2(μ) denote a Hilbert space associated with a 𝜎-finite atomic measure μ. We propose a characterization of antinormal composition operators on L2(μ). © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
Assessment of Bioactive Potential and Characterization of an Anticancer Compound from the Endophytic Fungi of Ocimum sanctum
(Pleiades Publishing, 2024) A. Verma; K. Kumar; U. Talukdar; G. Pal; D. Kumar; P. Shukla; S. Patel; A. Kumar; A. Kumar; R.N. Kharwar; S.K. Verma
Abstract: The goal of this study was to isolate endophytic fungi from Ocimum sanctum L. and to evaluate their biological potential, including antibacterial, antioxidant, and enzymatic activities and further characterization of the bioactive compounds. Nine endophytic fungi were isolated from the leaves and stem tissues of O. sanctum collected from the botanical garden of Banaras Hindu University, Varanasi, India. All isolates were identified based on their microscopic structures and molecular sequencing of the ITS rDNA. Aspergillus clavatonanicus (SS7) and Cochliobolus hawaiiensis (SL3) showed the highest colonization frequencies in the stem and leaves (16 and 14%, respectively). All fungal isolates were tested for extracellular enzymatic activities of amylase, cellulase, and pectinase. Of the nine fungal isolates, 60% tested positive for amylase and cellulase, whereas 50% showed pectinase activity. Using a disc diffusion assay, the extracted secondary metabolites were checked for antibacterial activity against three human pathogenic bacteria. Two isolates, SL2 and SS7, exhibited the highest antibacterial activity against all pathogens, including Enterococcus faecalis, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus (MRSA). Crude extracts of the six fungal isolates showed positive antioxidant activity. The crude extract of Aspergillus allahabadii (isolate SL2) showed strong antibacterial and antioxidant activities and crystallized during purification. X-ray crystallography confirmed the identity of the crystal as citrinin, which also exhibited strong anticancer activity against Dalton’s lymphoma cells. The results of this study suggest that endophytic fungi isolated from the leaf and stem tissues of Ocimum sanctum are potential sources of antibacterial, antioxidant, and anticancer compounds. © Pleiades Publishing, Ltd. 2024. ISSN 0026-2617, Microbiology, 2024, Vol. 93, No. 4, pp. 459–471. Pleiades Publishing, Ltd., 2024.
Assessment of predacity and efficacy of Arthrobotrys dactyloides for biological control of root knot disease of tomato
(2006) D. Kumar; K.P. Singh
Five isolates of Arthrobotrys dactyloides were isolated from different locations of India and their in vitro predacity was tested against Meloidogyne incognita (J2), Tylenchorhynchus brassicae and Hoplolaimus indicus. All isolates of A. dactyloides captured and killed M. incognita and T. brassicae but not H. indicus. The isolates also differed in their predacity of the first two nematode species. The application of mass culture of A. dactyloides in soil infested with 2000 juveniles of M. incognita per 'kg' before planting of tomato seedlings reduced the number of root knots by 5.6-45.6%, of females by 44.7-72.9%, of egg masses by 44.5-51.3% and of juveniles by 37.9-81.8% and increased the plant growth in a pot experiment. The effect of this fungus as biocontrol agent was enhanced when its mass culture was applied with cow dung manure, which reduced the number of root knots by 61.7-66.6%, of females by 80.6-94.7%, of egg masses by 80.3-89.6% and of juveniles by 68.1-88.0%. © 2006 Blackwell Verlag.
Autoradiographic studies on RNA synthesis and transport in the Salivary gland of Lygaeus sp. (Hemiptera-Lygaeidae)
(Birkhäuser-Verlag, 1981) D. Kumar
Autoradiographic studies using3H-uridine in the salivary gland of adult Lygaeus sp. were carried out. The gland cell nuclei, particularly the multiple nucleoli, are the sites of incorporation of the label exhibiting RNA synthesis. The labelled molecules (RNA) are transported to the cell cytoplasm and then into the gland lumen in which no turnover of the radioactivity is observed. © 1981 Birkhäuser Verlag.
Biomass of nematode and associated roots: A determinant of symptom production in root knot disease of rice (Oryza sativa L.)
(2006) K.P. Singh; R.K. Jaiswal; N. Kumar; D. Kumar
The biomass of Meloidogyne graminicola developing in rice roots was studied in relation to the expression of disease symptoms. The biomass of invading second stage juveniles (0.09 μg) increased to 33 μg on day 16 when adult females were in advance egg laying stage, with an increase of approximately 360-fold. Initiation of leaf yellowing was related to the ratio between total nematode and total root biomass of rice seedlings. Plants with nematode-to-root biomass ratios above 1:161 did not show any symptom while those with ratios between 1:138 and 1:121 exhibited yellowing. Plants with nematode-to-root biomass ratios between 1:115 and 1:60 showed moderate stunting while those with ratios between 1:43 and 1:20 exhibited severe stunting. The wilting symptoms occurred at or below 1:14 nematode-to-root biomass ratio. The yellowing of leaves in seedlings inoculated with graded inocula was expressed when the nematode-to-root biomass ratios reached to 1:136 on day 15 at 1000 J 2, 1:138 on day 9 at 3000 J2, 1:134 on day 7 at 6000 J2 and 1:129 on day 5 at 9000 J2 per pot. In rice nurseries, seedlings showing moderate stunting, severe stunting, wilting and wilting with single gall recorded nematode-to-root biomass ratios of 1:92, 1:20, 1:12 and 1:14 respectively. In severely stunted transplanted rice, the nematode-to-root biomass ratio ranged from 1:84 to 1:75. © 2006 The Authors.
Classical and Bayesian Estimation of Parameter of SSE(ε)-distribution Under Type-II Censored Data
(Gnedenko Forum, 2022) P. Kumar; D. Kumar; P. Kumar; U. Singh
In this present piece of work, we have considered a lifetime distribution based on trigonometric function called SSE(ε)-distribution and discuss its various properties which have not been added previously by host as well as any other authors. This distribution is useful and a good contribution in research under trigonometric function. We are deriving some more useful properties such as moments, conditional moments, mean deviation about mean, mean deviation about median, order statistics etc. Estimation of parameter has been done for both classical and Bayesian paradigms under Type-II censored sample. Simulation study has also been carried out to know the progress of the estimators in the sense of having smallest risk (over the sample space) at the long-run use. © 2022 Reliability: Theory and Applications. All rights reserved.
Copper toxicity in the fresh water cyanobacterium nostoc linckia
(1985) D. Kumar; M. Jha; H.D. Kumar
The effect of copper (CuC12.2H2O) on growth, heterocyst frequency, acetylene reduction, H2production and photosynthetic O2evolution of Nostoc linckia was studied. Whereas copper inhibited growth and other physiological processes, it increased heterocyst frequency and H2production. We conclude that copper pollution could considerably alter nitrogen dynamics in fresh water systems. © 1985, Applied Microbiology, Molecular and Cellular Biosciences Research Foundation. All rights reserved.
Developmental studies on proteins from haemolymph, fat body and ovary of a phytophagous bug, Dysdercus koenigii (Heteroptera: Pyrrhocoridae)
(1994) K.J. Venugopal; D. Kumar; A.K. Singh
[No abstract available]
Dielectric behaviour of valence compensated system Ba1-xlaxSn1-xNxO3
(IOM Communications Ltd., 2000) S. Upadhyay; D. Kumar; O. Parkash
Compositions in the system Ba1-xLaxSn1-xNixO3 up to x ≤ 0.30 were prepared by solid state sintering, and the dielectric behaviour of single phase solid solutions studied. It has been found that solid solutions form for compositions with x ≤ 0.15, the structure remaining cubic, similar to BaSnO3. The grain size of all the sintered compositions was almost the same as that for BaSnO3, i.e. 2-3 μm. Dielectric relaxation in these materials is explained on the basis of the reorientation of dipoles due to hopping of electrons among Ni2+ and Ni3+ ions. © 2000 IoM Communications Ltd.
Effect of fluorides on silicates and phosphates
(1961) D. Kumar; R.G. Ward; D.J. Williams
Thermogravirnetric measurements on silicate-phosphate-fluoride melts have been carried out in dry and water-saturated air-streams using a high-temperature balance. From the weight losses observed and the analysis of fluorine, the loss of fluorine can only be accounted for as SiF4 and HF, respectively in the absence and presence of water in the silicate-fluoride melts. The interaction of water with phosphate-fluoride and silicate-phosphate-fluoride melt appears to be similar to that in the silicate-fluoride melts. The known differential effect of fluorspar on the viscosities of acid and basic slags, the thermogravimetric measurements and the infra-red measurements on quenched silicate-fluoride melts are compatible with two different mechanisms of solution of the fluoride. It is proposed that in acid melts the fluoride ions are linked with silicons as Si-F bonds, whereas in melts containing more than 55-60 mole % metal oxide, the tendency towards Si-F bonding decreases markedly and fluorine is present largely as independent F- ions.
Effect of in additive on the photosensitivity of glassy Se 80Te20 alloy
(2009) N. Mehta; D. Kumar; A. Kumar
Photo-electrical measurements are done on thin films of Se 80-xTe20Inx (0 ≤x ≤ 20) to see the effect of In on the photoconductive properties of binary Se80Te 20 alloy. The photosensitivity (σph/σ d) and activation energy of photoconduction (δEph) are determined for this purpose. It has been found that σph/ σd and Eph are decreased with increasing concentration of the third element. The results are explained in terms of the increase in density of the defect states with the increase in concentration of the additive in thin films of Se80-xTe20Inx.
Effect of PbO–B2O3–BaO–SiO2 glass additive on dielectric properties of Ba0.5Sr0.5TiO3 ceramics for radio-frequency applications
(Elsevier Ltd, 2019) P. Tripathi; P. Kumari; V.K. Mishra; R. Singh; S.P. Singh; D. Kumar
In this work, the effects of PbO–B2O3–BaO–SiO2 (PBBS) glass addition (in increasing wt%) into Ba0.5Sr0.5TiO3 (BST0) ceramic on sintering, phase, and dielectric properties of BST0 are studied. The Ba0.5Sr0.5TiO3 (BST0) ceramic was synthesized by the conventional solid-state reaction method, and the PbO–B2O3–BaO–SiO2(PBBS) glass was formed by melting and quenching process. The PBBS glass with different weight percentages (3, 5, 8 and 10 wt%)is added to BST0 ceramic (BST3, BST5, BST8, and BST10, respectively) as a sintering aid to reduce the sintering temperature. Addition of glass helps in better sintering at lower temperatures with the presence of liquid phase at the respective sintering temperatures. The results of liquid phase-sintered ceramics are compared with the BST0 ceramic sintered at 1523 K. The BST10 with 10 wt% glass showed the lowest sintering temperature of 1148 K. Rietveld refinement analysis of BST0 ceramic confirmed the formation of single phase with cubic crystal structure. X-ray diffraction patterns of all liquid phase-sintered ceramics showed that the glass has minimal reaction with the BST0 ceramic and does not affect the crystal structure. Dielectric characterization was performed within the temperature range 20–450 K and frequency range 1 kHz to 1 MHz. It is revealed that the transition temperature shifted with different weight percentage of glass addition. All the compositions exhibit the paraelectric phase at room temperature. Dielectric properties were also measured in the microwave frequency range 8.5–11 GHz at room temperature. BST10 shows the stable and highest dielectric constant (average value of εr = 27) with lowest dielectric loss (tanδ = ∼0.121). Fourier transform infrared (FTIR) and Raman spectroscopy confirmed the formation of desired compositions by detecting molecular vibrations and chemical bonding. The synthesized ceramic is a low-cost candidate and can have potential uses in the radio-frequency applications. © 2018 Elsevier Ltd
Effect of Pr- and Nd-doping on structural, dielectric, and magnetic properties of multiferroic Bi0.8La0.2Fe 0.9Mn0.1O3
(American Institute of Physics Inc., 2014) Rahul Singh; G.D. Dwivedi; P. Shahi; D. Kumar; Om Prakash; A.K. Ghosh; Sandip Chatterjee
Bi0.8La0.15RE0.05Fe0.9Mn 0.1O3 (where RE = Pr and Nd) have been prepared via conventional solid state route. The Rietveld refinement of X-ray diffraction patterns shows that both systems crystallize in orthorhombic Pnma space group. Raman modes observed for these two systems indicate that both systems are very close to orthorhombic Pnma structure. Appearance of prominent A1-3 and weak E-2 modes in Bi0.8La0.15Nd0.05Fe 0.9Mn0.1O3 indicate the presence of chemically more active Bi-O covalent bonds (which favors stereochemical activity of Bi lone pair electrons) in comparison to Bi0.8La0.15Pr 0.05Fe0.9Mn0.1O3. Moreover, Bi 0.8La0.15Nd0.05Fe0.9Mn 0.1O3 system shows higher dielectric constant, low dielectric loss, and higher magnetization value in comparison to Bi 0.8La0.15Pr0.05Fe0.9Mn 0.1O3 system. Ferroelectric transition temperature decreases to 460 °C for both systems in comparison to 710 °C of Bi 0.8La0.2Fe0.9Mn0.1O3. The improved dielectric and magnetic response suggests Bi0.8La 0.15Nd0.05Fe0.9Mn0.1O3 a better multiferroic system than Bi0.8La0.15Pr 0.05Fe0.9Mn0.1O3. © 2014 AIP Publishing LLC.
Effect of some physiological factors on the nitrogenase and hydrogenase of the Azolla-Anabaena Azollae association
(1990) D. Kumar; A.B. Pandey; H.D. Kumar
Nitrogenase (acetylene reducing) activity, nitrogenase-mediated hydrogen evolution and hydrogenase-catalysed hydrogen uptake activity was studied in intact Azolla fronds. Nitrogenase activity was significantly influenced by various physiological parameters. When incubated under light, the rate of H2 evolved by the fronds under anaerobic conditions was significantly higher than that under aerobic condition. H2 uptake was significantly inhibited by both acetylene and carbon monoxide incubations. © 1990.
Effects of low temperature on two cyanobacteria
(1992) D. Kumar; J.B. Singh; H.D. Kumar
[No abstract available]
Efficient UV-visible up-conversion emission in Er3+/Yb 3+ co-doped La2O3 nano-crystalline phosphor
(2010) S.K. Singh; A.K. Singh; D. Kumar; O. Prakash; S.B. Rai
A nano-crystalline La2O3: Er3+/Yb 3+ phosphor sample has been synthesized through the solution combustion route using urea as a reducing agent. Thermal, structural and optical characterizations have been carried out to explore several of its properties. By thermal analysis one concludes to the presence of moisture and hydroxide phases [La(OH)3 and LaOOH] of lanthanum in the as-synthesized sample, which further changes to La2O3 phase above 600°C temperature. Up-conversion (UC) study shows the intense emission bands in the UV, blue, green and red regions. This paper also reports the first observation of UC emission bands extending up to the UV (240 nm) region on excitation with 976 nm wavelength. Heat treatment of the samples shows a change in the crystallite phase along with crystallite growth and relative UC luminescence intensities. The input pump power dependence shows the involvement of up to four photons. © 2009 Springer-Verlag.
Electrical conduction in calcium yttrium titanium cobalt oxide Ca1-xYxTi1-xCoxO3 (x≤0.15)
(1993) Om. Parkash; H.S. Tewari; V.B. Tare; D. Kumar
The DC resistivity and Seebeck coefficient have been measured as a function of temperature in the system Ca1-xYxTi1-xCoxO3 for the samples with x≤0.15 in the range 300-800 K. AC conductivity has been measured as a function of temperature and frequency. Results of these measurements show that electrical transport occurs mainly by a Debye-type loss process at temperatures less than 375 K and by excitation of charge carriers at localized states close to band edges and hopping among the localized sites.
Evaluation of highly conserved hsp65-specific nested PCR primers for diagnosing Mycobacterium tuberculosis
(International Union against Tubercul. and Lung Dis., 2017) P. Priyadarshini; K. Tiwari; A. Das; D. Kumar; M.N. Mishra; P. Desikan; G. Nath
OBJECTIVE : To evaluate the sensitivity and specificity of a new nested set of primers designed for the detection of Mycobacterium tuberculosis complex targeting a highly conserved heat shock protein gene (hsp65). DES I G N : The nested primers were designed using multiple sequence alignment assuming the nucleotide sequence of the M. tuberculosis H37Rv hsp65 genome as base. Multidrug-resistant Mycobacterium species along with other non-mycobacterial and fungal species were included to evaluate the specificity of M. tuberculosis hsp65 gene-specific primers. RESULT S : The sensitivity of the primers was determined using serial 10-fold dilutions, and was 100% as shown by the bands in the case of M. tuberculosis complex. None of the other non M. tuberculosis complex bacterial and fungal species yielded any band on nested polymerase chain reaction (PCR). The first round of amplification could amplify 0.3 ng of the template DNA, while nested PCR could detect 0.3 pg. CONC L U S ION: The present hsp65-specific primers have been observed to be sensitive, specific and costeffective, without requiring interpretation of biochemical tests, real-time PCR, sequencing or high-performance liquid chromatography. These primer sets do not have the drawbacks associated with those protocols that target insertion sequence 6110, 16S rDNA, rpoB, recA and MPT 64. © 2017 Chipinduro et al.