Browsing by Issue Date, starting with "2003"

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Effect of rice cultivars on rate of N-mineralization, nitrification and nitrifier population size in an irrigated rice ecosystem
(Elsevier, 2003) Paromita Ghosh; A.K. Kashyap
A study was conducted in irrigated rice fields planted to three rice (Oryza sativa) cultivars, Sarju-52, Malviya-36 and Pant Dhan-4, to investigate the influence of rice cultivars on rate of N-mineralization, nitrification and nitrifier population size. Thirty-day-old seedlings were transplanted in the waterlogged condition. Urea was the only fertilizer applied, at a rate of 100 kg N ha-1 in three split doses. The experiment was laid out in a randomized complete block design with three replicate plots for each cultivar and treatment. Soil mineral-N content, N-mineralization, nitrification and the most probable number of ammonium and nitrite oxidizing bacteria were estimated on six dates within the cropping period. It was observed that the mineral-N content in soil was lowest beneath Pant Dhan-4 under both unfertilized (control) and fertilized conditions. Mineral-N values in plots planted to Malviya-36 had intermediate values, while plots planted to Sarju-52 had highest mineral-N content under both control and fertilized conditions. Throughout the cropping season the lowest rate of N-mineralization, nitrification and nitrifier population was recorded in soil beneath Sarju-52 and highest beneath Pant Dhan-4. The highest vigour in terms of plant growth, grain yield and root porosity, was observed in Pant Dhan-4, followed by Malviya-36 and Sarju-52. Intercultivar differences in plant biomass production, which indicates the differences in nitrogen utilization potential and indirectly the quantity and quality of litter production may explain in part the differences in N-mineralization processes. The nitrifying bacterial population was strongly correlated with root biomass and root air space. The rice cultivars differed significantly in aerenchyma tissue differentiation resulting in different degrees of aerobic conditions in their rhizosphere. This explains the differences in nitrifier populations harboured by each of the cultivars in their respective soils and the consequent differences in soil processes. Hence, apart from fertilizer management, choice of rice cultivar also affects nitrifier populations and their functions, which are responsible for supplying nutrients to the rice soil. © 2003 Elsevier B.V. All rights reserved.
Molecular electrostatic properties using point charges: Ab initio hybridization displacement charges combined with bond-centered charges
(2003) A.K. Singh; A. Kumar; P.C. Mishra
A new approximate scheme to compute hybridization displacement charges (HDC) in molecules at the ab initio level using bond-centered charges arising due to overlapping atomic orbitals has been developed. It has been applied at the SCF/6-31G** and SCF-CIS/6-31G** levels to the ground and excited states, respectively, of several polar and non-polar molecules. It is found that, statistically speaking, HDC computed using the present approach reproduce SCF dipole moments and surface molecular electrostatic potential (MEP) patterns quite satisfactorily. In some cases, HDC reproduce MEP features even somewhat better than the MEP-fitted CHelpG charges, particularly in molecules where MEP values around atoms vary rapidly, e.g. around the boron atom in certain molecules containing it, and homonuclear diatomic molecules. Some interesting information about molecular bonding, not available from other charge distributions, is revealed by the present approach, e.g. in lithium containing molecules. The present approach also appears to describe molecular electrostatic properties and molecular bonding better than that where the Löwdin's symmetry orthogonalized atomic orbitals are used. © 2003 Elsevier Science B.V. All rights reserved.
Studies on the synthesis, characterization and hydrogenation behaviour of new Zr1-xMmx(Cr0.8Mo0.2)2 AB2-type hydrogen storage materials
(2003) B.K. Singh; A.K. Singh; M.A. Imam; O.N. Srivastava
This paper deals with the improvement in the hydrogenation behaviour of ZrCr2 type alloys through substitutions at both the Zr and Cr sites. It has been found that the alloy Zr1-xMmx(Cr1-yMoy)2 exhibits better hydrogen storage capacity and kinetics as compared to the parent alloy ZrCr2 or its variant Zr(Cr1-yMoy)2. The optimum material has been found to correspond to Zr0.93Mm0.07(Cr0.8Mo0.2)2 which shows a high hydrogen storage capacity of ∼1.8 wt.% under ambient conditions. This is the highest storage capacity known so far for the ZrCr2 type hydrogen storage system. It should be pointed out that the storage capacity reported previously in the literature for the optimum material Zr(Cr0.8Mo0.2)2 has a value of 1.53 wt.% only. In addition to the higher storage capacity, the material Zr0.93Mm0.07(Cr0.8Mo0.2)2 also exhibits kinetics (5×10-4 m3/s/kg) that are faster than the known kinetics (3×10-4 m3/s/kg) for the ZrCr2 storage system. A correlation between structural/microstructural characteristics and the improved hydrogenation behaviour (higher storage capacity and faster kinetics) has been outlined. © 2003 Elsevier Science B.V. All rights reserved.
Application of polymer-modified hanging mercury drop electrode in the indirect determination of certain β-lactam antibiotics by differential pulse, ion-exchange voltammetry
(Wiley-VCH Verlag, 2003) Bhim Bali Prasad; Bhavana Arora
A selective and sensitive polymer-modified electrode was developed for β-lactam antibiotics (cefaclor, amoxycillin and ampicillin) present in formulated and blood plasma samples for the quantitative analysis in aqueous environment. The detection was made using an ion-exchange voltammetric technique, in differential pulse mode, on poly(N-chloranil N,N,N′,N′ -tetramethylethylene diammonium dichloride)-modified hanging mercury drop electrode of a three-electrode system (PAR Model 303A) attached with a Polarographic Analyzer/Stripping Voltammeter (PAR Model 264A). Antibiotics, which are electroinactive compounds, were essentially converted to their electroactive oxazolone analogues through acid treatment under drastic conditions (0.1 mol L-1 HCl, ∼85 °C, 2 h). These analytes in the form of their respective oxazolones were indirectly analyzed by oxazolone entrapment in the polymeric film through ion-exchange process at modified electrode surface (accumulation potential -0.20 V (vs. Ag/AgCl), accumulation time 120 s, pH 7.4, KH2PO4-NaOH buffer (ionic strength 0. 1 mol L-1), scan rate 10 mV s-1, pulse amplitude 25 mV). The limit of detection of cefaclor-derived oxazolone was found to be 2.12 nmol L-1 (0.82 ppb, S/N 3, RSD 3.21%) in terms of cefaclor (a representative β-lactam) concentration.
Anaesthetic considerations for minimal access surgery (MAS) in children
(2003) L.D. Mishra; G.K. Sinha; R.K. Verma
Though often called minimally invasive, the "Minimal Access Surgery (MAS)" appears a correct term for laparoscopically performed operations, more so in children. The term non invasive is false and minimally invasive is misleading, as many operations can be quite invasive. It is not synonymous with minor surgery and never a minor anaesthesia. The MAS is truly a great surgical advance in adults and is also becoming a useful tool in children, for many intra abdominal, thoracic (throracoscopy) and intracranial diagnostic and therapeutic procedures. The major benefits are thought to result from avoidance of a large incision and excessive tissue handling. Though fairly safe in experienced hands, serious surgical and anaesthetic complications are possible. These are essentially related to the experience of the treating staff and limited space available for manipulation in children. The anesthetist should ensure an empty stomach and urinary bladder and optimal hydration before induction of a balanced endotracheal anaesthesia, with adequate muscle relaxation, monitoring and post-operative follow up. He / she should be prepared if the procedure becomes lengthy with possible risks of bleeding and venous gas embolism. Finally a patient who is not fit for a conventional operation is also not fit for MAS.
Cytochrome P-450 expression and lipid peroxidation in gallbladder cancer
(2003) Manoj Pandey; Lal B. Sharma; Vijay K. Shukla
Background and Objectives: Carcinoma of the gallbladder is the commonest neoplasm of the biliary tract; however, the etiology of this tumor remains unclear. Methods: A case-control study was carried out comprising 50 patients with gallbladder cancer and 50 patients with cholelithiasis. Cytochrome P-450 estimation was carried out in the gallbladder tissue, and lipid peroxide product melonaldehyde (MDA) was measured in gallbladder bile. Statistical analysis was carried out by Student's t-test, and one-way analysis of variance (ANOVA). The Pearson correlation coefficient was calculated, and linear regression analysis was performed. Results: The mean cytochrome P-450 concentration was significantly higher in patients with carcinoma of the gallbladder than in controls (t = 3.9, P < 0.001; F = 15.2, P = 0.002). Similarly, the mean concentration of melonaldehyde was significantly higher among cancer patients than in patients with gallstones (t = 2.7, P < 0.003; F = 7.37, P = 0.0078). No significant correlation was observed between tissue MDA and cytochrome P-450 levels (Pearson r = 0.1, P = 0.28). Conclusions: The results of the present study show that the rise in concentration of MDA is independent of the rise in concentration of cytochrome P-450; however, this is statistically insignificant. This could be due to biliary stasis leading to a rise in biliary concentration of melonaldeyde that is disproportionate to its production. © 2003 Wiley-Liss, Inc.
Ferulic acid may prevent infection of Cicer arietinum by Sclerotium rolfsii
(2003) B.K. Sarma; U.P. Singh
High performance liquid chromatography analysis of different parts of Sclerotium rolfsii-infected and healthy seedlings of chickpea (Cicer arietinum) was carried out to examine the status of phenolic compounds. Three major peaks that appeared consistently were identified as gallic, vanillic and ferulic acids. Gallic acid concentrations were increased in the leaves and stems of infected plants compared to healthy ones. Vanillic acid detected in stems and leaves of healthy seedlings was not detected in infected seedlings. There was a significant increase of ferulic acid in those stem portions located above the infected collar region compared to minimal amounts in the roots of healthy seedlings. In vitro studies of ferulic acid showed significant antifungal activity against S. rolfsii. Complete inhibition of mycelial growth was observed with 1000 μg of ferulic acid/ml. Lower concentrations (250, 500 and 750 μg/ml) were also inhibitory and colony growth was compact in comparison with the fluffy growth of normal mycelium. Higher amounts of phenolics were found in the stems and leaves of S. rolfsii-infected seedlings in comparison to the healthy ones. A role for ferulic acid in preventing infections by S. rolfsii in the stems and leaves of chickpea plants above the infection zone is therefore feasible.
Variation of Parthenium hysterophorus in response to soil quality: Implications for invasiveness
(2003) C. Annapurna; J.S. Singh
The performance of Parthenium hysterophorus, native to the tropical Americas and invasive to several countries, was evaluated for response to soil quality. Phenological (six stages) and quantitative growth variables [relative growth rates in height (Rh) and diameter (Rd)] were measured every fortnight. Based on harvest data, the variables, root:shoot (R:S) ratio, specific leaf area (SLA), relative growth rate in biomass (Rw), net assimilation rate (NAR) and dry matter allocation to plant components, were determined. High clay content in soils prolonged the rosette stage, enhanced Rh and Rd and hampered root growth, but promoted biomass allocation to shoots. The extreme degree of plant mortality was observed, with only 33.3% individuals surviving to reproduce in the soils with highest clay contents. This appears to be one of the most important findings that certainly has a major bearing on the range of adaptation of the weed. Seed mass declined whereas seed production increased in relatively coarser soils with the exception of nearly pure sand. In soils rich in clay, plants produced a smaller number of larger seeds. These data suggest that variation in fundamental functional traits would enable P. hysterophorus to adjust to a variety of habitat conditions.
Antifungal activity and induced resistance in pea by aqueous extract of vermicompost and for control of powdery mildew of pea and balsam
(2003) U.P. Singh; S. Maurya; D.P. Singh
Vermicompost (VC) is a nutritionally rich natural organic fertilizer, which releases nutrients relatively slowly in the soil. It improves quality of the plants along with physical and biological properties of soil, i. e., soil aeration, water-holding capacity and ecological balance of microbial soil biota. Aqueous extracts of vermicompost (AVC) inhibited spore germination of several fungi. They also affected the development of powdery mildews on balsam (Impatiens balsamina) and pea (Pisum sativum) caused by Erysiphe cichoracearum and Erysiphe pisi, respectively, in the field at very low concentrations (0.1-0.5 %). Soil amendment with VC (1-5%) induced synthesis of phenolic acids in pea. Maximum phenolic acids were detected in pea plants treated with 4% VC followed by 3% as compared to control. The induction of phenolic acids in plants was correlated with the degree of resistance in treated as compared to non-treated (control) pea plants. The growth of plants grown in VC-amended soil was much better than the growth of plants raised in non-amended soil.
Pictorial CME. Pseudohypoparathyroidism type IA.
(2003) S.K. Bhadada; A.G. Unnikrishnan; R. Kumar; D.V. Reddy; N.K. Agarwal; S.K. Singh; J.K. Agrawal
[No abstract available]
Role of the dielectric constant of ferroelectric ceramic in enhancing the ionic conductivity of a polymer electrolyte composite
(2003) Pramod Kumar Singh; Amreesh Chandra
The effect of dispersal of ferroelectric ceramic materials Ba0.70Sr0.30TiO3 (Tc ≈ 30°C) and Ba0.88Sr0.12TiO3 (Tc ≈ 90°C) on the ionic conductivity of an ion conducting polymer electrolyte (PEO:NH4I) is reported. The addition of 3 wt% of Ba1-xSrxTiO3 (x = 0.30 and 0.12) results in an increase in the conductivity by one to two orders of magnitude. Further, a study on the temperature dependence of conductivity of these composites shows that the conductivity enhancement 'peaks' as we approach the dielectric phase transition of the dispersed ferroelectric material where the ε changes rapidly from ∼2400 to 7500 (for x = 0.30) and from 1100 to 5500 (for x = 0.12). This establishes the role of dielectric constant of the dispersoid in enhancing the ionic conductivity of the polymeric composites.
Formation of a new F.C.C. τ2 phase in rapidly quenched Al55Cu35V10 alloy
(2003) D.K. Misra; R.S. Tiwari; O.N. Srivastava
X-ray diffraction and transmission electron microscopy experiments were carried out to study the structure of rapidly solidified as-cast and annealed Al55Cu35V10 alloy. The as-cast Al55Cu35V10 alloy shows the presence of a new f.c.c. τ2 phase (a=0.58nm) along with a b.c.c. (a=0.89nm) phase which after subsequent annealing transforms into single f.c.c. phase (a=0.58nm). In this paper, it is also reported that these phases are crystalline approximants to an icosahedral phase on the basis of e/a (valence electron per atom) constant line.
Damping of ion-cyclotron whistler waves through ionospheric plasma
(Springer Berlin, 2003) Ashok K. Singh; Rajesh Singh
The propagation features of ion-cyclotron whistler waves through the hydrogen, helium and oxygen plasma are studied. Expression for temporal damping, spatial damping and the time development of wave amplitude is derived from the modified theory of cyclotron damping of ion-cyclotron whistler wave including thermal effect. It is shown that the temporal damping is dominant for wave frequencies closer to the ion gyrofrequencies. The variations in plasma conditions cause variation in sudden commencement of cyclotron damping, which occurs after finite time of propagation of ion whistlers. The results have been used to explain the sudden cut-off of the amplitude of ion whistler wave observed by rockets and satellites in the terrestrial ionosphere. It is shown that the present study can be used to estimate ion temperature of the plasma. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.
Mechanism of nucleosome disruption and octamer transfer by the chicken SWI/SNF-like complex
(Academic Press Inc., 2003) Anil K. Panigrahi; Raghuvir S. Tomar; Madan M. Chaturvedi
We had recently characterized SLC, a SWI/SNF-like chromatin remodelling activity, from chicken liver. The SLC efficiently disrupts nucleosomes, transfers histone octamers from nucleosomal substrates onto acceptor DNA, and slides histone octamers along DNA. Here, we present evidence that SLC is indeed a SWI/SNF homologue, and it disrupts nucleosomes by inducing extensive dynamic helical distortions in the nucleosomal DNA. Both the nucleosome disruption and octamer transfer functions are indifferent to nucleosomal histone tails. We further show that the nucleosome disruption precedes the octamer transfer and that the latter requires continuous presence of ATP. Based on these observations, we propose that a disrupted nucleosome is not a spontaneous substrate for octamer transfer; rather the nucleosome disruption and the octamer transfer are two temporally successive, ATP-dependent events during nucleosome remodelling by SLC in vitro. © 2003 Elsevier Science (USA). All rights reserved.
Massive falx cerebri empyema
(2003) A.K. Yende; S. Mohanty
A rare case of otogenic massive intra-falx empyema is reported. The patient presented with headache, vomiting and left lower limb weakness of 8 months duration. C.T. scan revealed two cavities in the falx. Right fronto-parietal craniectomy and drainage of massive empyema was undertaken through interhemispheric approach with wide opening of the falx, evacuation of voluminous amount of thick pus and marsupalization of flax with dura. The patient showed complete recovery. The relevant literature is briefly reviewed.
Antithrombin III activity in cerebrovascular accidents
(2003) V.P. Singh; M.K. Singh; V. Kumar; M.K. Sinha; R.C. Dwivedi; M. Rai; B. Dube
Cerebrovascular accidents are commonly due to occlusive or haemorrhagic lesions. The present prospective study was planned to find out role of antithrombin in possible etiopathological process, which might predispose an individual for stroke. Method: Biological activity of antithrombin III was done by the method as described by Innerfield et al (1976). Immunological estimation of an antithrombin III was done by single radial immunodiffusion by the technique of Mancini et al modified by Fahey and Mckelvey. Results: The biological and immunological activity of antithrombin III was measured in 98 patient of occlusive and 56 patients of haemorrhagic strokes. Significant depression in biological as well as immunological activity (p<0.001) was observed in occlusive stroke. In haemorrhagic stroke both, biological and immunological activity was increased. In follow up study, there was progressive normalization of both, biological as well as of immunological activity in both group. Conclusion: Decrease of antithrombin III in occlusive and increase in haemorrhagic stroke indicates that these changes have at least an additive role in the pathogenesis of stroke.
Studies of glass sands occurring around Shankargarh, district - Allahabad with reference to its economic viability
(2003) Ajai Srivastava; R.N. Tiwari; Diwakar Mishra; Kshitij Mohan
The present paper deals with the glass sands occurring around Shankargarh, district Allahabad. The sands in the area are predominantly whitish. However, other colours viz., pink, light yellow, yellow, brown, and red are also commonly found. More than 60 samples representing the vertical and lateral variations of the lithological units were collected from different parts of the area for grain size, mineralogical and geochemical analyses. The grain size analysis reveals that the majority of the grains are rounded, coarse to fine size grade, well sorted, finely skewed and platykurtic. Mineralogical study of the selected glass sand samples shows the presence of light minerals, i.e., quartz, mica, and chert and heavies-rutile, staurolite, tourmaline, and zircon. Opaques include magnetite and ilmenite. Geochemical analysis of these sands reveals a variation in SiO2 in between 97 per cent and 99.01 per cent, whereas Fe2O3 from 0.14 per cent to 1.41 per cent and Al2O3 0.12 to 1.89 per cent. The percentage of iron decreases with the increase of depth, thereby at the base white glass sand of purest variety is met with. Impurities in the form of iron oxide, glistening specks of mica, etc., have been observed in the glass sands. By treatment and beneficiation, iron, and aluminium contents of the glass sands of the area can be reduced for the purpose of making colourless glass. These sands can also be used for making the different types of glass, i.e., lime glass, lead glass, and silicate glass. The glass sands in the area have been found under thin cover of soil with a gentle ground slope. This has provided more time and opportunity for the rain water to percolate through and thereby facilitate the disintegration of the parent rock in the dry summer season.
Heliotrope rash and 'V' sign in dermatomyositis
(2003) P. Neehar; B. Benjamin; A. Sahu; A.K. Singh; I.S. Gambhir
[No abstract available]
Synthesis and characterization of Cu nanotubes and nanothreads by electrical arc evaporation
(2003) Ram Manohar Yadav; A.K. Singh; O.N. Srivastava
We report the formation and characterization of copper nanostructures, nanotubules and nanothreads, which were obtained by electrical arc evaporation of Cu electrodes under varied conditions of He ambience. Electrical arc evaporation was done with ∼10 V and (∼50-100 A) DC current. The current was used in a pulse mode. The evaporated material was condensed on a formvarcoated Cu grid mounted on a liquid N 2-cooled specimen holder. Transmission electron microscopy was employed to characterize the condensed materials. These investigations revealed that the condensed materials consisted of the mentioned nanostructures. Nanotubes and nanothreads are formed for a He pressure in the chamber corresponding to ∼140 and ∼500 torr, respectively. Extensive electron microscopic investigations showed that the diameter of the nanotubes varied from ∼5 nm to ∼50 nm and their length from 2 μm to 3 μm.
Tomato leaf curl Gujarat virus, a New Begomovirus Species Causing a Severe Leaf Curl Disease of Tomato in Varanasi, India
(American Phytopathological Society, 2003) S. Chakraborty; P.K. Pandey; M.K. Banerjee; G. Kalloo; C.M. Fauquet
The biological and molecular properties of Tomato leaf curl Gujarat virus from Varanasi, India (ToLCGV-[Var]) were characterized. ToLCGV-[Var] could be transmitted by grafting and through whitefly transmission in a persistent manner. The full-length genome of DNA-A and DNA-B of ToLCGV-[Var] was cloned in pUC18. Sequence analysis revealed that DNA-A (AY190290) is 2,757 bp and DNA-B (AY190291) is 2,688 bp in length. ToLCGV-[Var] could infect and cause symptoms in tomato, pepper, Nicotiana benthamiana, and N. tabacum when partial tandem dimeric constructs of DNA-A and DNA-B were co-inoculated by particle bombardment. DNA-A alone also is infectious, but symptoms were milder and took longer to develop. ToLCGV-Var virus can be transmitted through sap inoculation from infected tomato plants to the above-mentioned hosts causing the same symptoms. Open reading frames (ORFs) in both DNA-A and DNA-B are organized similarly to those in other begomoviruses. DNA-A and DNA-B share a common region of 155 bp with only 60% sequence identity. DNA-B of ToLCGV-[Var] shares overall 80% identity with DNA-B of Tomato leaf curl New Delhi virus-Severe (ToLCNDV-Svr) and 75% with ToLCNDV-[Lucknow] (ToLCNDV-[Luc]). Comparison of DNA-A sequence with different begomoviruses indicates that ToLCGV-[Var] shares 84% identity with Tomato leaf curl Karnataka virus (ToLCKV) and 66% with ToLCNDV-Svr. ToLCGV-[Var] shares a maximum of 98% identity with another isolate of the same region (ToLCGV-[MIr]; AF449999) and 97% identity with one isolate from Gujarat (ToLCGV-[Vad]; AF413671). All three viruses belong to the same species that is distinct from all the other geminivirus species described so far in the genus Begomovirus of the family Geminiviridae. The name Tomato leaf curl Gujarat virus is proposed because the first sequence was taken from an isolate of Gujarat, India.