Browsing by Issue Date, starting with "1998"

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Electrostatic potential mapping using hybridization displacement charge: Atomic parameters and transferability of charge and potential
(John Wiley and Sons Inc., 1998) C. Gopi Mohan; P.C. Mishra
Molecular electrostatic potential (MEP) maps and MEP-derived charges for certain molecules were studied by the ab initio approach using the 6-31G basis set. These results were used to obtain the parameters (K and ) for fluorine, sulfur, and chlorine required for the hybridization displacement charge (HDC) calculations employing the MNDO and AMI methods. The HDC combined with Löwdin charges, distributed continuously in three-dimension spherically and symmetrically, were shown to reproduce ab initio MEP features of molecules fairly well. This method of computing the MEP was applied to two molecules of pharmacological importance, namely, dimaprit and mustard gas. It is shown by studying the as and trans forms of two amino acids that transferability of the MEP is appreciably less acceptable than that of charges in going from one conformation to the other. © 1998 John Wiley & Sons, Inc.
Genetic mapping of the amide response element(s) of the hspω locus of Drosophila melanogaster
(1998) S.C. Lakhotia; Madhu G. Tapadia
Small chromosomal deletions [Df(3R)e(R-1) and Df(3R)e(P)] with intact hsrω transcription units but with variable deletions of the upstream region were used to map the upstream regions that regulate heat shock and amide responsivity of the 93D puff (hsrω locus) in salivary glands of late third instar larvae of Drosophila melanogaster. The Df(3R)e(P) deletion, generated by a P-element mobilization screen, removed the 93B6-7 to 93D3-5 cytogenetic region. [3H]uridine-labeled transcription autoradiograms revealed that normal developmental and heat shock-induced expression of the 93D puff remained unaffected in both the deficiency chromosomes. However, the amide responsivity of the 93D site was lost on the Df(3R)e(P) homolog while the Df(3R)e(R-1) homolog responded normally to amides. Southern hybridizations with a series of upstream probes mapped the distal break point of the Df(3R)e(P) deletion between -22 kb and -23 kb of the hsrω transcription unit. Since the distal breakpoint of Df(3R)e(R-1) is at about -45 kb upstream of the hsrω gene it is inferred that the amide response element(s) that modulate the specific transcriptional activation of the 93D puff following treatment of salivary glands with a variety of amides is/are located in the -22 kb to about -45 kb upstream interval. The Df(3R)e(P) and Df(3R)e(R-1) deletions also abolished dosage compensation at the 93D locus as well as the effect of β-alanine levels on its heat shock inducibility.
Polyindole modified potassium ion-sensor using dibenzo-18-crown-6 mediated PVC matrix membrane
(Elsevier, 1998) P.C. Pandey; R. Prakash
A potassium ion-selective electrode using PVC matrix membrane impregnated with dibenzo-18-crown-6 at the surface of the polyindole modified electrode is reported. The electroactivity of the polyindole film contributing to the high selectivity of the neutral carrier based ion-sensor is analyzed based on the cyclic voltammetry. The polyindole modified electrode is formed by the electropolymerization of the indole monomer in dichloromethane containing tetrabutyl ammonium perchlorate (TBAP). A highly stable electroactive polyindole film is obtained. A neutral carrier impregnated PVC membrane is formed by casting over the surface of the polyindole modified electrode. The resulting ion-selective electrode without the incorporation of polyanions shows high reproducibility with negligible drift of the standard potential with a slope of 53 mV/decade. The lowest detection limit for the potassium ion sensor is 7.0 × 10-6 mol dm-3 with a wide linearity over almost five decades. A typical response of the neutral carrier impregnated PVC membrane over the polyindole modified electrode to the potassium ion is reported. © 1998 Elsevier Science S.A. All rights reserved.
Short communication: Bacillus cereus capable of degrading SDS shows growth with a variety of detergents
(1998) Kusum Lata Singh; Arvind Kumar; Ashok Kumar
A strain of Bacillus cereus was isolated from a detergent-polluted pond. This strain showed growth with exceedingly high concentration of both anionic and non-ionic detergents. Detergent such as SDS was rapidly taken up by the cells and degraded to dodecan-1-ol by the enzyme alkylsulphatase.
Effect of hydrogen exposure on the interface state density in titanium dioxide based MOS gas sensor
(SPIE, 1998) D. Dwivedi; R. Dwivedi; S.K. Srivastava
Mechanism of the formation of hydrogen induced interface states at the Si/TiO2 interface has been investigated by conductance measurement of metal oxide semiconductor gas sensor. The conductance voltage response of the fabricated MOS capacitor has been studied upon exposure to hydrogen in argon ambient. The fabricated MOS device is sensitive to hydrogen (1-3%) at room temperature. The interface state density (Nit) is determined from the G-V curve, using a bias scan conductance method at fixed frequency. It is observed that, change in conductance is better at lower frequencies, which may be due to the balanced communication of interface traps with valance and conduction band of silicon substrate. Further it has been concluded that, present investigation provides a method for more accurate calculation of hydrogen induced interface traps in such device.
Acute paraparesis with tuberculous meningitis
(BMJ Publishing Group, 1998) R.K. Garg
[No abstract available]
Simple approach for the detection and identification of individual gases/odours using an integrated sensor array
(SPIE, 1998) V.K. Singh; R. Dwivedi; S.K. Srivastava
In the present paper, a simple pattern recognition approach for application in the detection and identification of individual gases/odours using the response of an array of eight sensors has been presented. The proposed approach has been validated using experimental data for three different gases.
Cytogenetic response of hexavalent chromium-induced somatic cell abnormalities in Allium cepa
(1998) A.N. Sahi; S.K. Singh; P.K. Sen; R.N. Singh
Hexavalent chromium present in water inhibited root growth due to its toxicity and its accumulation in roots. The Cr (VI) concentration in water samples ranged from 0.003 to 0.750 mg/l in and around the Sukinda valley, which was higher than the Government permissible limit. The Cr (VI)-containing water was utilized by local inhabitants for drinking and agricultural practices which produced increases in human health hazards and mutations or cell death in plants. The cytological effect of hexavalent Cr was investigated using onion roots grown in chromium contaminated water samples. The most pronounced chromosome aberration(s) encountered was stickiness followed by bridges with or without fragments, chromosomes with inactivated centromeres, variations of C-mitosis, vagrant chromosomes and micronuclei. The presence of C-mitosis appeared to be due to complete inhibition of spindle fibres. Mitotic chromosomal abnormalities were more numerous and death to the cell occurred at higher concentrations. Local inhabitants were advised not to drink the Cr-contaminated water nor to eat below ground plant parts.
Connection between low- and high-momentum transfer-spin observables
(1998) R. Nag
The Fock space of the nucleon is extended to include states with three quarks and a gluon together with states of the type three quarks and a quark-antiquark pair. The probabilities of various states are determined using the experimental results of deep inelastic scattering. It is found that the resulting wavefunction is able to correlate spin observables measured at low-momentum transfer (F, D and GA/GV) with those measured in high-momentum transfer using a single multiplicative constant, apart from the usual QCD correction factor. This constant is determined by comparison with experimental values.
Compressive strength and tensile strength of rocks at sub-zero temperature
(1998) R.D. Dwivedi; P.K. Singh; T.N. Singh; D.P. Singh
The present paper deals with the uniaxial compressive and tensile behaviour of Chunar sandstone and Makrana marble at sub-zero temperature (0°C to -20°C) in dry and wet conditions. It was found that uniaxial compressive and tensile strengths of these rocks increased with decrease in temperature below 0°C. Both strengths in general and tensile strengths in particular of wet rocks increased more rapidly in comparison to dry rocks.
Detection of nitric oxide using an optical sensor
(1998) P.C. Pandey
An optical sensor for nitric oxide (NO) is described. The sensor involves a flow injection analysis (FIA) system coupled with an evanescent wave (EW) sensor employing total internal reflection of fluorescence radiation (TIRF). The detection is based on the measurement of the decrease in fluorescence response in the presence of NO of a highly fluorescent product which is the complex of glutathione and 7-diethylamino-3-(4′-maleimidylphenyl)-4-methylcoumarin (CPM). CPM forms a highly fluorescent product with thiol containing compound i.e. cysteine/glutathione which can be detected using an evanescent fluorosensor. NO form a stable complex with glutathione/cysteine which then does not react with CPM to form fluorescent product. Thus there is a decrease in the fluorescence signal on increasing concentration of NO with constant concentration of glutathione. An excellent FIA response has been observed on the injection of the constant concentration of CPM-glutathione product obtained by treating constant concentration of glutathione with varying concentration of NO. The lowest detection limit of NO is found to the order of 0.10 μM.
Redefining status of pathology and microbiology.
(1998) P.K. Shukla
[No abstract available]
Occurrence of polyovular follicles and its possible significance in the ovary of the bat, Scotophilus heathi
(1998) U.P. Singh; J. Doval; Amitabh Krishna
Seasonal changes in the number of polyovular follicles were estimated in a Vespertilionid bat, Scotophilus heathi. The largest number of polyovular follicles was observed during September, which coincided with the period of maximum development of intra-ovarian rete cells cord. It has been suggested that interaction between rete cells cord and follicle may be responsible for giving rise to a number of polyovular follicles in the medullary region of the ovary. Most of the polyovular follicles observed were biovular and they grow maximum up to the late preantral stage. Polyovular follicles with four or more oocytes were observed during September and they do not grow beyond stage I of the follicular development. The polyovular follicles were generally short lived and may contribute to the extensive development of the interstitial cells in S. heathi.
Electrocatalytic properties of lanthanum manganite-based oxides obtained by a low temperature method
(1998) A.N. Jain; S.K. Tiwari; R.N. Singh
Pure and Sr-doped lanthanum manganites have been synthesized by a-non-conventional hydroxide solid solution precursor route at 500°C. Their electrochemical and electrocatatytic properties in relation to O2 evolution in KOH solutions have been investigated as film electrodes by cyclic voltammetry, AC impedance and Tafel polarization techniques. The oxide powders have been used to obtain catalytic films on the nickel supports by painting with a slurry of the oxide followed by sintering at 400°C. The electrochemically active area vis-a- vis the electrocatalytic activity of the oxides increases considerably with increasing Sr-content from 0.1 to 0.4 mole in the perovskite lattice. Both, the apparent as well as the true, catalytic activities of the oxide are found to be many times higher than those of the samples prepared by conventional ceramic methods. The electrolytic evolution of O2 follows approximately first order kinetics in OH- concentration. The Tafel slopes are in the range 90-140 mV decade-1.
Cadmium induced growth of 2223 phase and Tc enhancement in TBCCO high Tc thin films
(Elsevier, 1998) H.K. Singh; O.N. Srivastava
Cd doped Tl-2223 thin films (̃ 1 μm) have been grown by annealing B2Ca2CdxCu3Oy (x = 0.0, 0.1, 0.2, 0.3) precursor films, deposited on MgO (100) by ultrasonic spray pyrolysis, in Tl2O ambient in an evacuated (> 10-5 Torr) sealed quartz tube at 890°C for 2 h. Doping by Cd has been found to induce the growth of 2223 phase and an enhancement in Tc. The Tc of the as-grown thin films samples are 118 K, 120 K, 124 K and 121 K respectively for Cd contents x = 0.0, 0.1, 0.2 and 0.3. The observed Tc = 124 K for x = 0.2 is higher than the previously observed highest Tc of 122 K for Tl-2223 thin films. A distinguishing feature of the present synthesis route is the fact that oxygen has not been used at all in the entire synthesis process. The transport Jc of the 0.2 Cd doped film is 1.12 × 105 A/cm2 (77 K, 0 T). The surface morphology of these films shows a very dense growth of platelet-like grains. © 1998 Published by Elsevier Science B.V.
Antihepatotoxic activity of Eclipta alba in albino rats
(1998) R.K. Upadhyay; J.P.N. Chansouria; V.B. Pandey
The antihepatotoxic activity of Eclipta alba was studied by in vivo assay methods using carbon tetrachloride induced acute hepatitis in albino rats. Administration of different extracts of Eclipta alba significantly inhibited the CCl4 induced increase in the transaminases and alkaline phosphatase activity. Of all the extracts maximum hepatoprotective activity was observed in MeOH extract followed by ethyl acetate and petroleum ether extracts of Eclipta alba.
Organic maturation study of Permian coal seams, Rajmahal Basin, Bihar
(1998) Mahendra P. Singh; Prakash K. Singh
The coals are sub-bituminous to highj volatile bituminous in rank and show evidences of 'bituminization' stage of maturation. they have distinctive petrographic characteristics being rich in secondary liptinites such as exsudatinite (nil to 7.66%), bitumenite (0.94 to 28.88%) and fluorinite (nil to 0.99%). The rock-eval data suggest that they are hydrogen-rich and have immature organic matter-kerogen type III. The study corroborates the earlier contention regarding the onset of 'oil window' at Rom of 0.5% and suggests that the paleodepth of burial of the coal bearing horizon in the Rajmahal basin was from 1890 to 2970m. The loss of cover has been estimated to range from 1440 to 1720m.
Effect of Dispersion and Distribution on Activity of Alumina-Supported Cadmium Sulfide Photocatalysts for Hydrogen Production from Water
(American Chemical Society, 1998) Manjit K. Arora; A.S.K. Sinha; S.N. Upadhyay
Activity of a cadmium sulfide photocatalyst, for hydrogen production by decomposition of water using visible light, depends on the protocol used for its preparation. In the present work, unsupported and alumina-supported CdS photocatalysts were prepared by various techniques and characterized by N2 adsorption, X-ray diffraction, electron diffraction, and X-ray photoelectron spectroscopy. The results indicate that the activity is strongly affected by the dispersion and distribution of CdS on alumina. High dispersion and preferential distribution of CdS on the surface of alumina yield superior activity. The catalyst activity has been explained with the help of its microstructure.
Synthesis of isomaleonitrile dithiolato bridged heterobimetallic complexes, M[Pb(i-MNT)2], and their conductance behaviour
(1998) Nanhai Singh; Lal Bahadur Prasad
Heterobimetallic complexes of the type M[Pb(i-MNT)2] (M=Ni(II), Co(II), Zn(II), Cd(II), Cu(II) and dioxouranium(VI); i-MNT = isomaleonitriledithiolate2-] have been synthesized and characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility, infrared and UV-visible spectral studies. Solid state electrical conductivity measurements suggest that the complexes behave as semiconductors. Their conductivities increase with the increase in temperature from 308 to 353 K. One of the compounds, Zn[Pb(i-MNT)2], shows aband gap (1.02 eV) which is quite worthy of further investigations.
Complexes of butyltin(IV) with monothioacetylacetone and tert-butyltrifluoroacetylacetone
(Taylor and Francis Ltd., 1998) Rajendra Prasad Singh
The reaction of butyltin(IV) trichloride with the sodium salt of monothioacetylacetone and tert-butyltrifluoroacetylacetone results in formation of monomeric complexes BuSnCI3-n- (MeCSCHCOMe)n and BuSnCI3-n(CF3COCHCO'-Bu)n (n = 1 -3). All the complexes were characterized by elemental analyses, IR, NMR (1H, 13C, 119Sn, 19F), molar conductance and molecular weight determination. The results show that in all the complexes Iigands coordinate to tin(IV) as bidentate donors.