Browsing by Author "H. Kumar"

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A tertiary trisomic interchange heterozygote in pea (Pisum sativum L.)
(Birkhäuser-Verlag, 1983) V.C. Mercykutty; H. Kumar
In M2 generation of an interchange heterozygote, one off-type plant was isolated which was characterized by the presence of weak and slender stems, with profuse semi-spreading branching, narrow and yellow-green foliage, small and weak pods, and 10 days late-flowering and-maturing as compared to wildtype. The mutant had high pollen and ovule sterility (76-80%) and showed 5II+2II (heteromorphic)+1I (small chromosome) in 85% of the cells. The mutant appeared to be a tertiary trisomic interchange heterozygote. The possible mechanism of the formation of heteromorphic bivalents and a small chromosome are discussed. © 1983 Birkhäuser Verlag.
Acute renal failure due to intrinsic renal diseases: Review of 1122 cases
(2003) Jai Prakash; D. Sen; N. Sarat Kumar; H. Kumar; L.K. Tripathi; R.K. Saxena
In this study we have analyzed incidence, causes and clinical course of ARF due to primary intrarenal disease other than acute tubular necrosis. Thousand hundred and twenty two cases of ARF of diverse etiology were studied over a period of 16 years; July 1984 to Dec, 1999. Surgical ARF 231 (20.6%) were not included in the present study. Intrinsic renal diseases were responsible for ARF in 891 (79.4%) of cases. The most common intrinsic renal diseases 705 (79.4%) causing ARF were ischemic/toxic acute tubular necrosis, but not included in this study. Acute renal failure was related to acute glomerulonephritis (9.3%), acute interstitial nephritis (7%), and renal cortical necrosis in (4.6%) of cases. Therefore intrinsic renal diseases other than ATN were the causative factor for acute renal failure in 186 (20.8%) patients in our study. Crescentic (51.8%) and endocapillary proliferative glomerulonephritis (34.9%), were the main glomerular diseases responsible for ARF and 75.9% of GN was related to infectious etiology. Fifty three percent of acute interstitial nephritis was drug induced and in 25 (40%) patients it was related to an infectious etiology. Renal cortical necrosis due to HUS was observed in 16 (39%) children and majority (76.47%) of the cases had a diarrhoeal prodrome. Obstetrical complications were the main causes (61%) of cortical necrosis in adults with acute renal failure. Thus, intrinsic renal diseases other than ATN were responsible for ARF in 186 (20.8%) cases. Post-infectious glomerulonephritis, acute interstitial nephritis and renal cortical necrosis (complicating HUS in children and obstetrical complications in adult) are the main causes of acute renal failure in our study. Both acute GN and interstitial nephritis had excellent prognosis, however renal cortical necrosis was associated with a very high mortality.
Acute renal failure in pregnancy
(1998) J. Prakash; H. Kumar
Acute renal failure (ARF) in pregnancy constitutes 15-22% of all cases of ARF referred for dialysis in Indian patients. In contrast, ARF is a rare complication of pregnancy in developed countries. Majority of gravida (60- 70%) developed ARF following septic abortion and the remaining gravida women (30-40%) had ARF due to the complications of late pregnancy i.e. eclampsia, intrauterine foetal death, uterine haemorrhage. The etiopathogenesis of ARF in a given case is multifactorial. The various factors which attribute to ARF are blood loss, hypotension, sepsis, intravascular hemolysis, disseminated intravascular coagulation, volume depletion and septic shock. Histologically, acute tubular necrosis is seen in vast majority of patients, and renal cortical necrosis is observed in 20-25% of cases. The irreversible lesion of renal cortical necrosis is almost similar in both early and late pregnancy. However, the incidence of renal cortical necrosis is higher in renal failure associated with septic abortion. The disease has high maternal mortality and septicemia is the main cause of death in these patients with acute renal failure.
Calorimetric studies of thermal crystallization in glassy Se 80-xTe20Snx (0≤x≤10) alloys
(2011) H. Kumar; N. Mehta; K. Singh
This paper reports a calorimetric study of the crystallization kinetics in glassy Se80-xTe20Snx (0≤x≤10) alloys in terms of kinetic parameters of crystallization (crystallization temperature Tc, activation energy of crystallization Ec and order parameter n) and thermodynamic parameters of crystallization (enthalpy of crystallization Hc and the entropy of crystallization Sc). © 2011 The Royal Swedish Academy of Sciences.
Calorimetric study of specific heat in glassy Se-Te-Sn-Bi system using MDSC technique: Effect of Bi incorporation
(2013) A. Sharma; H. Kumar; N. Mehta
Bismuth has historical significance as a modifier in chalcogenide glasses due to the p- to n-type transition at a particular composition of definite glassy systems after its incorporation. We have synthesized some new quaternary glasses using Bi as a modifier in ternary Se78Te20Sn 2 alloy as parent glass in light of this information. Modulated differential scanning calorimetry measurements have been made on glassy Se 78-x Te20Sn2Bix (0 ≤ x ≤ 6) alloys for specific heat studies. We have observed an expected enormously large increase in the specific heat values in the glass transition region. The composition dependence of specific heat values above the glass transition temperature (Cpe) and below the glass transition (Cpg) is also discussed in this article. © 2013 Copyright Taylor and Francis Group, LLC.
Calorimetric study of thermal crystallization kinetics in Se78−xTe20Sn2Pbx (0 ≤ x ≤ 6) alloys
(2013) H. Kumar; N. Mehta
Glassy samples of Se78−xTe20Sn2Pbx (0 ≤ x ≤ 6) system are prepared by melt quenching method. For non-isothermal study of crystallization kinetics, DSC scans have been taken at the heating rates 5, 10, 15 and 20 K/min in non-isothermal mode. Activation energy of crystallization (Ec) has been calculated using Kissinger method, Matusita-Sakka method and Augis-Bennett method. Various kinetic parameters of crystallization kinetics like peak crystallization temperature (Tc), Rate constants (K) and order parameter (n) are determined using these DSC scans. Thermodynamic parameters such as crystallization enthalpy (ΔHc) and entropy change during the crystallization (ΔS) are also evaluated. Results are discussed using chemical bond approach. © EDP Sciences 2013.
Chiasma Formation in Induced Autotetraploids of Pea (Pisum sativum L.)-An efficient method of scoring
(1990) H. Kumar; C.P. Srivastava; V.C. Mercykutty
Chiasma formation plays an important role in the process of recombination leading to the production of diverse types of gametes. In diploids, the nature and frequency of chiasma formation have been resolved in a variety of crop plants (Darlington 1932, Fedak 1973, David 1974, Jones 1974, Parker 1975, Srivastava and Balyan 1977, Srivastava 1980 a, b, and others). However, induced autotetraploids, which have varying levels of gametic fertility, have not received adequate attention (Kaul 1964, Hazarika and Rees 1967, Dynansagar and Sudhakaran 1970, Hossain and Moore 1975, and others). Moreover, pea has inherent drawback of abnormal meiosis even in diploid (Gottschalh 1968, Blixt 1972, Muller 1976) leading to poor resolution of chromosomes until metaphase I and hence, it is difficult to resolve the chiasma formation. This paper examines the attempt of scoring chiasma formation at metaphase I and its subsequent partitioning in autotetraploids of four diverse genotypes of pea (Pisum sativum L.). © 1990, Japan Mendel Society, International Society of Cytology. All rights reserved.
Composition dependence of specific heat in Se80-x Te 20Sn x chalcogenide glasses
(2013) A. Sharma; H. Kumar; N. Mehta
Differential Scanning Calorimetry (DSC) is performed at different heating rates under non-isothermal conditions to study the specific heat studies of glassy Se80 - x Te20Sn x (0 ≤ x ≤ 10) alloys. An extremely large increase in the specific heat values has been observed at the glass transition temperature. It has also been found that the values of C p below glass transition temperature (C pg ) and after glass transition (C pe ) are highly composition dependent. This indicates that the Sn additive used in the present study influences the structure of the glassy Se80Te20 alloy. The results show that C p values reveal local extrema in Se-Te-Sn glassy system at x = 4 and x = 8. The composition dependence of both parameters (C pe and C pg ) has been explained in terms of the glassy structure of Se-Te-Sn system. © 2013 Pleiades Publishing, Ltd.
Composition dependence of thermal stability, micro-hardness and compactness in glassy Se90In10-xGex alloys
(2009) H. Kumar; N. Mehta; K. Singh; A. Kumar
In the present work, the effect of Ge incorporation is studied on the thermal stability, micro-hardness and compactness of glassy Se90In10 alloy. Thermal stability of glassy Se90In10-xGex alloys has been studied using differential scanning calorimetric technique. Micro-hardness of glassy Se90In10-xGex alloys is measured at room temperature. The compactness of the structure of Se90In10-xGex alloys is also determined from the measured densities. The variation in micro-hardness and compactness with composition has been discussed. © 2009 Elsevier B.V. All rights reserved.
Compositional dependence of thermal transport and optical properties of Se85 Ge15-x Pbx (0≤ x ≤10) chalcogenide glassy alloys
(Elsevier B.V., 2019) Pankaj K. Mishra; K. Singh; A.N. Upadhyay; H. Kumar
In the present work, the ratio of germanium (Ge) to lead (Pb) is varied keeping the concentration of selenium(Se) fixed in the glassy system, Se85 Ge15-x Pbx (0 ≤ x ≤ 10) to optimize the thermal transport and optical properties. The differential scanning calorimetry (DSC) measurements were carried out in the non-isothermal mode to know glass transition temperature (Tg), crystallization temperature (Tc) and melting temperature (Tm). DSC scans of some samples(4 ≤ x ≤ 10) exhibit two glass transition temperatures (Tg), which indicates the presence of co-existing phases in glassy samples. The values of effective thermal conductivity (λe),effective thermal diffusivity(χe) and volumetric heat capacity(QCp) have been determined using transient plane source (TPS) measurements. These parameters show a non-monotonous behavior with the variation of Pb content in the prepared series. These results are explained in terms of chemical bond approach, changes in thermal transfer processes and mechanism of phonon scattering under transitions from dilute to concentrated solid solution. Band gap and Urbach energy have been estimated using Uv–Vis spectroscopy. Optical band gap (~0.65 eV) is minimum for the sample having 4 at.% of Pb. A signature of exciton formation is obtained for this critical composition. Results are explained using structural defect model and by degree of disorder induced, as indicated by a change in intensity and position of the Raman peak corresponding to Se–Se bonds. © 2019 Elsevier B.V.
Crescentic glomerulonephritis in association with traumatic arteriovenous fistula following gun shot injury
(1998) H. Kumar; R.G. Singh; Jai Prakash; Usha; C.R. Kar; K.S. Basavaraj
[No abstract available]
Determination of specific heat in multi-component chalcogenide glasses of SeTeSnPb system using modulated differential scanning calorimetry
(2012) A. Sharma; H. Kumar; N. Mehta
In the recent past, glass physicists have focused their attention on the element lead as a modifier due to observation of carrier-type reversal in chalcogenide glasses for a particular composition of certain glassy systems after the incorporation of lead. Keeping this fact in mind, some new quaternary glasses have been synthesized using Pb as modifier in the ternary Se 78Te 20Sn 2 alloy parent glass. Specific heat studies have been made in glassy Se 78-xTe 20Sn 2Pb x(0≤x≤6) alloys using the modulated differential scanning calorimetry (MDSC) technique. An extremely large increase in the specific heat values has been observed at the glass transition temperature. The composition dependence of specific heat values below glass transition temperature (C pe) and after glass transition (C pg) has been also explained. © 2012 Elsevier B.V.
Effect of Bismuth incorporation on some thermomechanical properties of glassy Se78Te20Sn2 alloy
(National Institute of Optoelectronics, 2012) H. Kumar; A. Sharma; N. Mehta
We have synthesized some novel chalcogenide glasses from the Se-Te-Sn-Bi system. The basic thermo-mechanical parameters such as micro-hardness, volume (Vh) and formation energy (Eh) of micro-voids in the glassy network, as well as the modulus of elasticity E have been calculated in present glasses. The composition dependence of micro-hardness is also discussed.
Effect of lithium ion irradiation on the glass transition kinetics of Se98In2 chalcogenide glass
(2010) H. Kumar; N. Mehta; K. Singh; N.S. Saxena
Glass transition kinetics in glassy Se98In2 alloy is studied using differential scanning calorimetry under two different conditions. In the first condition, normal samples of the present glass are used. In the second condition, the ion-irradiated samples are used to see the effect of ionic irradiation on the glass transition kinetics of present alloy. For this high energetic beam (50 MeV) of lithium ions is used. After the ion irradiation on the glass, drastic changes in kinetic parameters of glass transition are observed. The results are explained by the model developed by Kastner et al. (Valence-alternation model for localized gap states in lone-pair semiconductors, Phys. Rev. Lett. 37 (1976), pp. 1504-1507).
Effect of lithium-ion irradiation on the crystallization kinetics of glassy Se98In2
(2009) H. Kumar; N. Mehta; K. Singh; N.S. Saxena
Differential scanning calorimetry (DSC) has been used to study the crystallization kinetics of glassy Se98In2 both before and after irradiation of the alloy with high-energy (50 MeV) lithium ions. After the ion-irradiation, significant changes in the kinetic parameters of crystallization of the glass were observed. The results are explained in terms of a model involving irradiation-induced defects.
Effect of some chemical modifiers on the glass/crystal transformation in binary Se90In10 alloy
(2011) H. Kumar; N. Mehta; A. Kumar
This work reports the effect of Ge, Sb, Sn additives on the thermally activated glass to crystal phase transition in binary Se90In 10 alloy. Differential scanning calorimetry (DSC) technique is used for this purpose. Different kinetic parameters of glass/crystal transformation have been calculated. The results are explained using the chemical bond approach for the covalent network of such glasses. © 2010 Akadémiai Kiadó, Budapest, Hungary.
Effect of tin incorporation on thermo-mechanical properties of glassy Se80Te20 alloy
(IOP Publishing Ltd, 2014) H. Kumar; A. Sharma; N. Mehta
We report an analysis on the hardness behavior of glassy Se 80-xTe20Snx alloy. The crucial thermo-mechanical parameters (micro-hardness, volume and formation energy of micro-voids and the modulus of elasticity) are examined. The results indicate that the thermo-mechanical parameters are changed significantly after incorporation of Sn in glassy Se80Te20 alloy. © 2014 Chinese Physical Society and IOP Publishing Ltd.
Fertility Improvement in Autotetraploids of Pea — Selection for Seed‐Set and Disjunction Index
(1993) H. Kumar; V.C. Mercykutty; C.P. Srivastava
Four seed‐set groups of plants, viz. unselected ‘general’ and selected ‘high’, ‘medium’ and ‘low’ were constituted in C1 generation from randomly selected autotetraploids of two pea cultivars, T 163 and 5064‐S. In C2 generation, ten plants were selected at random in each of the four groups. Two seeds each from selected autotetraploids were drawn and bulked to make 20 seeds in each of the four groups to raise C3 generation. Selection resulted in a gradual shift in seed‐set, though the magnitude and nature varied with the group and generation. Improvement in the seed‐set from C1 to C3 generation was associated with the increase in bivalents per cell, disjunction index and total chiasmata. Increase in total chiasmata was mostly due to an increase in proximal ones. Increase in seed‐set was reflected in improvement of grain yield per plant. Copyright © 1993, Wiley Blackwell. All rights reserved
Formation of silver particles in [PVA:CS:PEG]-AgNO3 based biopolymer electrolyte membranes: Structural and electric transport properties study
(Elsevier B.V., 2023) R.K. Prajapati; H. Kumar; A.L. Saroj
[Chitosan (CS)-poly(vinyl) alcohol (PVA)-polyethylene glycol (PEG-200)]+xwt% silver nitrate (AgNO3) (x = 0, 10, 20, 30, 40) based biopolymer blend electrolytes (BPBEs) were prepared using solution casting method. FTIR results show the interaction of Ag+/NO3− with the constituents of polymers CS/PVA. XRD results reveal that the amorphousness increases with increasing AgNO3 concentration. Optical morphological (OM) images show that the silver, Ag(o) particles are agglomerated on the surface of the membrane. Temperature dependent dc conductivity (σdc) and dielectric relaxation frequency (fr) for BPBEs follow the Arrhenius type behavior and the sample containing 30 wt% salt has optimum dc conductivity, σdc ∼1.7×10−4 S/cm at 30oC with lowest activation energy∼ 0.16 eV. The ac conductivity spectra follow the Jonscher's power law (JPL) with power law exponent, s > 1. The scaling of AC conductivity and loss tangent (tanδ) spectra were performed with respect to temperatures/concentrations of salt. The dielectric permittivity study reveals that the electrode polarization effect predominates at low frequencies. The Ionic Transference Number (ITN) measurement was used to determine the nature species of charge carrier, either ionic or electronic. The linear sweep voltammetry (LSV), result shows that 30% AgNO3 containing sample has the electrochemical stability window (ESW) ∼+1.5 to -1.5 V. © 2023 Elsevier B.V.
Genetic analysis of adult plant resistance to powdery mildew in pea (Pisum sativum L.)
(Kluwer Academic Publishers, 1981) H. Kumar; R.B. Singh
An analysis of adult plant resistance of powdery mildew in 15 F1, F2 and F3 populations of pea derived from crossing 15 diverse and susceptible lines with one resistant line revealed that resistance to powdery mildew is controlled by duplicate recessive genes. The genes were designated as er1 and er2. Disease reaction showed independent segregation with three known markers in the resistant parent, namely, af (afila, chromosome 1), st (stipule reduced, chromosome 3) and tl (clavicula, chromosome 7). © 1981 Veeman B.V., Wageningen.