Showing papers by "North Eastern Hill University published in 1996"
TL;DR: A review of hydroxylapatite, a biological material of extensive contemporary inter-disciplinary research, can be found in this article, where the authors provide information on preparation techniques, characterization, isomorphous substitutions and solubility equilibria.
Abstract: A few significant physico-chemical aspects of hydroxylapatite, a biological material of extensive contemporary inter-disciplinary research, have been reviewed. Updated information on preparation techniques, characterization, isomorphous substitutions, and solubility equilibria is provided. Recent research trends and aspects which require further clarification have been emphasized.
437 citations
TL;DR: In this article, the interaction of phenazinium dyes with nonionic surfactant Triton X100 increases in the order PSF < SFT < SFO < MO.
83 citations
TL;DR: In this article, the seasonal dynamics of microbial biomass C, N and P were studied in 7-, 13-and 16-year-old regrowths of a disturbed subtropical humid forest in north-east India.
75 citations
TL;DR: The position of the LLCT band is largely dependent on the substituent type on the catechol frame and is qualitatively assigned as the 3b 1 (cat) → π*(aap) transition as mentioned in this paper.
52 citations
TL;DR: In this paper, the decay dynamics of fine roots and N and P mineralization pattern were studied in forest regrowths of three different ages in a humid subtropical region of India.
48 citations
TL;DR: The tegumental surface of Artyfechinostomum sufrartyfex as viewed under the scanning electron microscope revealed the presence of double rows of spines in the collar and sloughing off of most of the spines or their deformation as well as wrinkles and rupture of the general teguments.
Abstract: The tegumental surface of Artyfechinostomum sufrartyfex as viewed under the scanning electron microscope revealed the presence of double rows of spines in the collar. The dorsal surface (6–8 rows) and the ventral surface are provided with posteriorly directed spines. The normal body surface of Fasciolopsis buski shows posteriorly directed scales throughout the ventral surface; the dorsal surface is free of any scales but has domed, coarsely distributed papillae. When treated in vitro with ethanol root-tuber extract of Flemingia vestita, an indigenous medicinal plant in Meghalaya, India, at a concentration of 5, 10, and 20 mg/ml phosphate-buffered saline (PBS), A. sufrartyfex became paralyzed within 1.1–1.4, 0.8–1.0, and 0.3–0.5 h, respectively. Following similar treatment, F. buski took 3.0–3.6, 1.5–2.0, and 0.6–0.8 h, respectively, to reach a paralytic state. Oxyclozanide B.P. was used as the reference drug and paralyzed the worm, taking slightly less time than the crude extract for both species of flukes. Stereoscanning observations on the tegumental surface of treated (20 mg extract/ml PBS) A. sufrartyfex revealed sloughing off of most of the spines or their deformation as well as wrinkles and rupture of the general tegument. Severe tegumental alterations and deformities were also displayed by F. buski exposed to 20 mg extract/ml PBS.
46 citations
TL;DR: In this article, a subtropical Pinus kesiya Royle Ex. Gordon forest in north-east India was studied, and the results showed that tree fall and tree cutting substantially altered community structure, and therefore soil nutrient status.
43 citations
TL;DR: In three stands of a subtropical humid forest of north-east India representing different stages of regrowth after tree cutting, biomass of both fine and coarse roots followed a unimodal growth curve by showing a gradual increase from spring/pre-rainy season to autumn/post-rainY season.
Abstract: Seasonal variation and depthwise distribution of dry matter in roots of different diameter classes and their annual production were studied using sequential core sampling. The investigations were carried out in three stands of a subtropical humid forest of north-east India representing different stages of regrowth after tree cutting. The mean annual standing crop of fine (<2 mm in diameter) and coarse (2–15 mm diameter) roots increased gradually from 5.4 Mg ha-1 and 0.7 Mg ha-1 in 7-yr old regrowth to 9.4 Mg ha-1 and 2.8 Mg ha-1 in 16-yr old regrowth, respectively. The contribution of fine roots to the total root mass declined from 88% in 7-yr old regrowth to 77% in both 13 and 16-yr old regrowths, while that of coarse roots increased from 12 to 23%. A major portion of fine roots (59–62%) was present in 0–10 cm soil layer, but the coarse roots were concentrated in 10–20 cm soil depth (38–48%). In all the three stands, biomass of both fine and coarse roots followed a unimodal growth curve by showing a gradual increase from spring/pre-rainy season to autumn/post-rainy season. Biomass to necromass ratio increased from 2.5 in the 7-yr old to 3.2 in the 16-yr old stand. The annual fine root production increased from 5.9 Mg ha-1 to 7.7 Mg ha-1 and total root production from 7.6 Mg ha-1 to 14.7 Mg ha-1 from 7-yr to 16-yr old regrowth.
40 citations
TL;DR: In this paper, an efficient trans diastereoselective synthesis for azetidinones 3 having 3-dienyl functionalities was developed, which first involved the [2 + 2] cycloaddition of butadienylketene with variou...
Abstract: An efficient trans diastereoselective synthesis for azetidinones 3 having 3-dienyl functionalities was developed. The method first involved the [2 + 2] cycloaddition of butadienylketene with variou...
37 citations
TL;DR: In this article, a detailed analysis of the particle spectrum of the non-minimal supersymmetric standard model (NMSSM), containing two Higgs doublets and a singlet, in the limit tan β ⋍ m t m b.
31 citations
TL;DR: In this paper, a direct synthetic route, based on silver assisted metal exchange reaction, to cationic bis-ligand complexes of copper involving N-aryl-pyridine-2-aldimines (L, 1) has been studied.
TL;DR: Quinolinium dichromate in water oxidizes vicinal and nonvicinal diols to the corresponding alpha-hydroxy carbonyl compound and can be correlated with a mechanistic pathway involving the intermediate formation of a chromate ester, which undergoes decomposition to give the product.
Abstract: Quinolinium dichromate (QDC) in water oxidizes vicinal and nonvicinal diols to the corresponding α-hydroxy carbonyl compound. The rate is proportional to the concentrations of diol, oxidant and hydrogen ions, and the reactions proceed almost twice as fast in D2O than in H2O. These data can be correlated with a mechanistic pathway involving the intermediate formation of a chromate ester, which undergoes decomposition to give the product.
TL;DR: The cryoprotectant (CSP1) comprising sucrose, dimethylsulfoxide (DMSO) and glycerol (10, 10, 5%, w/v) gave the best survival of bromegrass cells exposed to liquid nitrogen (LN) as determined by regrowth and fluorescent diacetate (FDA) staining.
TL;DR: In this paper, the authors evaluated the impact of shortening of the jhum cycle on the ecosystem productivity and economic yield in a young and an old jhum fallow in North-Etern India.
Abstract: Cropping on jhum fallows in north-eartern India is predominantly done for one year in a jhum cycle. If second year cropping is done, expanse of the forest land required for slashing and burning could be reduced significantly. We tested this hypothesis in a young (6 yr) and an old (20 yr) jhum fallow. We also evaluated if the productivity during second year cropping could be alleviated by auxiliary measures such as tilling the soil or application of fertilizers (chemical or farm-yard manure or both in combination). The results demonstrate that the ecosystem productivity (total dry matter production) and economic yield (rice grain production) decline with shortening of jhum cycle. Second year cropping causes a further decline in ecosystem productivity in old jhum field, but not in young jhum field. Economic yield from second year cropping in its traditional form (without any fertilizer treatment) is not much lower than that in the first year, and can be improved further by manuring the soil. Tilling of soil improves neither ecosystem productivity nor economic yield. Different fertilization treatments respond differently; while inorganic manuring enhances ecosystem productivity, a combination of inorganic and organic manuring improves economic yield
TL;DR: The cyclopropanes 2a-h having 4-(bismethylthio)butadienyl moiety as donor group, which are easily obtained by regioselective cycloproanation of vinylogous ketene dithioacetals with oxodimethylsulphonium methylide, undergo facile Lewis acid assisted vinylcyclopropyl rearrangement to afford substituted and spiro cyclopentenes 3a-H in good yields as discussed by the authors.
TL;DR: In this article, the potential alpha energy exposure (PAEE) due to radon and its progenies has been measured in dwellings at five different locations in the north-eastern region of India.
TL;DR: In this paper, the viscosities of aqueous sodium nitrate and sodium thiosulphate solutions were measured as functions of temperature ( ⋍288.0-328.4 K ) and concentration (from dilute to almost saturation point).
TL;DR: In this paper, the Ricci scalar and Dirac spinors were considered in four-dimensional curved spacetime and it was shown that a large number of fermion-antifermion pairs can be produced by the exponential expansion of the early universe.
Abstract: It has been noted that at high energy the Ricci scalar is manifested in two different ways, as a matter field as well as a geometrical field (which is its usual nature even at low energy). Here, using the material aspect of the Ricci scalar, its interaction with Dirac spinors is considered in four-dimensional curved spacetime. We find that a large number of fermion-antifermion pairs can be produced by the exponential expansion of the early universe.
TL;DR: In this article, substituted 1-methyl and 2-methylnaphthalenes, 5-methyl- and 6-methyl -1,2,3,4-tetrahydroanthracenes have been synthesized in good yields through 1,2- addition of the corresponding α -lithio- o -or m -xylenes onto α-oxoketene dithioacetals or their dihydro derivatives.
TL;DR: In this paper, the formation and characterization of (oxoferryl)tetraphenylporphyrin ((TPP)FeIVO) as a result of photodisproportionation of the μ-oxo dimer, (Fe(TPP))2O, obtained on solubilization of Fe(TPP)Cl in an aqueous alkaline TX-100 detergent micelle, under 441.6 nm laser excitation at room temperature and at −50 °C.
Abstract: We report the formation and characterization of (oxoferryl)tetraphenylporphyrin ((TPP)FeIVO) as a result of photodisproportionation of the μ-oxo dimer, (Fe(TPP))2O, obtained on solubilization of Fe(TPP)Cl in an aqueous alkaline TX-100 detergent micelle, under 441.6 nm laser excitation at room temperature and at −50 °C. The other photoproduct is identified as a five-coordinated, high-spin (5cHS) ferrous complex.
TL;DR: Fluoride amino acid complexes of vanadium(IV) of the type A[VOF 2 L(H 2 O)] (A = Naor NH 4, L = cysteinate) and A [VOF 3 L 2 O] (A= NH 4 for alanine and A = Na, NH 4 or K for serine) have been synthesized.
TL;DR: Acyclic and cyclic aroyl ketene N,S-acetals undergo regioselective deprotonation-cyclization via dipole stabilized carbanion in the presence of LDA/THF to afford the corresponding 2-(cycloalkylamino)-4-aryl or 3,4-annelated thiophenes in moderate to good yields as mentioned in this paper.
TL;DR: An upper bound on the mass of the lightest neutralino in a supersymmetric theory containing an arbitrary number of singlet, doublet, and triplet Higgs superfields under the standard model gauge group is derived.
Abstract: We derive an upper bound on the mass of the lightest neutralino in a supersymmetric theory containing an arbitrary number of singlet, doublet, and triplet Higgs superfields under the standard model gauge group. Assuming grand unification of the gauge couplings, whereby the theory reduces to the minimal supersymmetric standard model with an arbitrary number of singlets, the bound can be expressed in terms of the gluino mass. Including radiative corrections, the upper bound on the mass of the lightest neutralino is 62 GeV for B gluino mass of 200 GeV, which increases to 178 GeV for a 1 TeV gluino.
TL;DR: In this paper, α-oxoketene dithioacetals were shown to undergo highly selective conjugate reduction with Zn/ZnCl 2 -TMEDA in refluxing ethanol under controlled reaction conditions to afford β-methylthiomethylene ketones.
TL;DR: In this article, the cycloalkanones (1a-lf) were converted into their corresponding carboxylates (2a-2f) by a lead (IV) acetate promoted rearrangement in presence of perchloric acid in triethyl orthoformate.
TL;DR: The carbinol acetals 2a-h obtained by 1,2-addition of propargylmagnesium bromide to acyclic α-oxoketene dithioacetals as mentioned in this paper undergo cycloaromatization in the presence of trimethyl borate/methanol to give 2,5-bis(alkylthio)biphenyls 4a-henic oxy-Cope rearrangement and an unprecedented 1,4-alkyl-thio shift in the resulting allenic intermediate.
TL;DR: Spores of Frankia strain ACN1AG, immobilized in calcium alginate beads, germinated to produce colonies that increased in protein content and showed nitrogenase activity, opening the possibility of using beaded spores as inocula.
Abstract: Spores of Frankia strain ACN1AG, immobilized in calcium alginate beads, germinated to produce colonies that increased in protein content and showed nitrogenase activity. Air dried immobilized spores remained viable for at least 15 days in dry condition, making the storage and transport of Frankia strains easy. This also opens the possibility of using beaded spores as inocula.
Journal Article•
TL;DR: Human kidney T1-cells were exposed in vitro to various doses up to 3 Gy of 6 MeV neutrons and compared with the effect caused by gamma photons, finding neutrons were about 4-fold more efficient as compared to gamma rays.
Abstract: ADP-ribosylation (ADPR) of proteins has been shown to be involved with a variety of cellular responses in which chromatin organization and functions are affected. In order to look into this response, human kidney T1-cells were exposed in vitro to various doses up to 3 Gy of 6 MeV neutrons and compared with the effect caused by gamma photons. Whereas in case of neutrons the maximal inhibition of ADPR was reversed at 0.37 Gy, that in case of gamma-rays occurred at 1.5 Gy. For the reversal of inhibition of ADPR of proteins in T1-cells, neutrons were about 4-fold more efficient as compared to gamma rays.
TL;DR: A new lower bound is obtained on the heavy SU(4${)}_{\mathit{C}}$ gauge boson mass due to Pati and Salam to be g${906}_.\mathrm{\ensuremath{-}}195}^{+241}$ TeV.
Abstract: Using the most recent experimental limit on ${\mathit{K}}_{\mathit{L}}$\ensuremath{\rightarrow}\ensuremath{\mu}e\ifmmode\bar\else\textasciimacron\fi{}, the inputs from the CERN LEP measurements, and the top-quark mass, we obtain a new lower bound on the heavy SU(4${)}_{\mathit{C}}$ gauge boson mass due to Pati and Salam to be ${\mathit{M}}_{\mathit{C}}$g${906}_{\mathrm{\ensuremath{-}}195}^{+241}$ TeV. \textcopyright{} 1996 The American Physical Society.
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TL;DR: In frogs, the signals are meant to attract and assess the sex, species identity and genetic quality of potential mates as discussed by the authors, which plays a central role in the courtship behavior of frogs.
Abstract: Vertebrate vocalization came into existence for the first time in frogs. Acoustic signals produced by the frogs have well-defined physical characteristics and a clear biological meaning. The signals are meant to attract and assess the sex, species identity and genetic quality of potential mates. Acoustic communication plays a central role in the courtship behaviour of frogs.