Showing papers by "Banaras Hindu University published in 1991"

Microbial C, N and P in dry tropical forest soils: Effects of alternate land-uses and nutrient flux

Abstract: The effects of alternate land-uses (savanna, cropfield and mine spoil) on microbial C, N and P in dry tropical forest soil of India were studied. The mean microbial C, N and P, respectively, in the four major systems ranged from 250 to 609 μg C g −1 , 27 to 65 μg N g −1 and 12 to 26 μg P g −1 . The microbial biomass in these systems was characterized by a mean C:N:P ratio of 23:2:1. The microbial C, N and P were positively related to root biomass and total plant biomass (aboveground + root biomass). The derived ecosystems (savanna, cropland and mine spoil) have changed from the original forest ecosystems in terms of soil features and microbial biomass. The conversion of forest into other land-uses resulted in remarkable decline in the amounts of soil nutrients and microbial C, N and P. The microbial nutrients in this dry tropical environment are sensitive to land-use changes. The calculated flux of N and P through the microbial biomass ranged from 27 to 64 kg N ha −1 yr −1 and 13 to 26 kg P ha −1 yr −1 . Thus, in this dry tropical environment the microbial biomass appears to contribute substantially to the N and P requirements of higher plants.

Serum trace elements and Cu/Zn ratio in breast cancer patients.

Abstract: Serum copper, zinc, and the Cu/Zn ratio were measured in 55 patients with breast disease (20 with benign breast diseases and 35 patients with breast cancer) and 30 controls. The mean serum copper levels were higher in breast cancer than in benign breast diseases (167.3 μg/dl) vs. 117.6 μg/dl) (P<).001) and controls (167.3 μg/dl vs. 98.8 μg/dl) (P<0.001). Patients with advanced breast cancer had higher serum copper levels than did patients with early breast cancer (177.9 μg/dl vs. 130.4 μg/dl) (P <0.001). The mean serum zinc levels were lowered only in patients with advanced breast cancer as compared with controls (88.6 μg/dl vs. 115.1 μg/dl) (P < 0.001). Serum zinc levels were not decreased in patients with early breast cancer and benign breast diseases. The Cu/Zn ratio was increased in breast cancer patients (1.91 vs. 0.86) (P < 0.001) but not in patients with benign breast diseases. The precise mechanisms responsible for the alterations in trace element levels in breast cancer patients are still unclear and require further evaluation. However, the serum copper levels and the Cu/Zn ratio may be used as biochemical markers in these patients.

Nitrogen-mineralization in dry tropical savanna: effects of burning and grazing

Abstract: The effects or burning and grazing on plant available nitrogen (NO3-N + NH4-N) and N-mineralization in a dry tropical savanna were examined. The plant available N ranged from 2.8 to 10.6 μg g−1 with maximum values in the dry period (summer season) and minimum values in the wet period (rainy season). The trend for N-mineralization was opposite to that of the size of the available N pool. N-mineralization rates ranged from 1.8 to 30.6 μg g−1 mo−1 within an annual cycle. On average the pool of available N was 54% higher in the burned treatment and 48% higher in the grazed treatment compared to the protected treatment, similarly the mean annual N-mineralization was 20% higher in the burned and 16% higher in the grazed savanna.

Recovery of injured Campylobacter jejuni cells after animal passage.

Abstract: Sixteen freeze-thaw-injured nonculturable stocks of Campylobacter jejuni were passed through rat gut, and seven were reisolated. These reisolated strains were converted to toxin producers, as they were before preservation, following consecutive passages through rat gut. This observation indicated the existence of an injured, viable, but nonresuscitated form of C. jejuni which can be resuscitated to a culturable and fully virulent form by passaging the organism through a susceptible host.

Enhanced frequency of chromosome aberrations in workers occupationally exposed to diagnostic X-rays.

Abstract: To estimate the level of radiation exposure of personnel handling diagnostic X-ray machines, the yield of chromosomal aberrations was analysed in peripheral blood lymphocyte cultures. These occupationally exposed individuals showed higher frequencies of dicentrics as well as acentrics than normal controls. Absorbed radiation doses calculated by extrapolating reference in vitro dose-response curve for dicentrics ranged between 0.13 and 0.17 Gy. This implies exposure beyond the permissible limit of 0.05 Gy/year for the whole body. However, no obvious trend of increased aberrations as a function of either duration of employment or age was noticed. The increase in the aberration yields in this personnel underscores the need of adopting measures to avoid or minimise such overexposure.

Some Bianchi-type cosmological models in a new scalar-tensor theory

Abstract: Bianchi type I, III, V, VI0, and Kantowski-Sachs type models have been investigated in a scalar tensor theory developed by Saez and Ballester (1985) and Saez (1985). The dynamical behaviour of the models has also been analyzed.

Spoil characteristics and vegetation development of an age series of mine spoils in a dry tropical environment

Abstract: A series of coal mine spoils (5, 10, 12, 16 and 20-yr old) in a dry tropical environment was sampled to assess the changes with time in spoil characteristics, species composition and plant biomass. Coarse fragments (>2 mm) decreased with age of mine spoil while the proportion of 0.2–0.1 mm particles increased. Total soil N, mineral N, NaHCO3-extractable Pi, and exchangeable K increased with age of mine spoil and these parameters were lower in mine spoils than native forest soil even after 20 years of succession. Exchangeable Na decreased with age of mine spoil and in 20-yr old spoil it was higher than native forest soil. Plant community composition changed with age. Only a few species participated in community formation. Species richness increased with age, while evenness and species diversity declined from 5-yr old to 16-yr old community with an increase in the 20-yr old community. A reverse trend occurred for concentration of dominance. Area-weighted shoot and root biomass of other species increased with the age of the mine spoil while that of Xanthium strumarium patches declined with age. Data collected on spoil features, microbial C, N and P, and shoot and root biomass when subjected to Discriminant Analysis indicated a continued profound effect of age. 10 and 12-yr old mine spoils were closer to each other, and 5 and 20-yr old spoils were farthest apart.

Removal of ni(II) from aqueous solutions by sorption

Abstract: Adsorption of Ni(II) from its aqueous solutions on China clay, a cheap clay mineral, has been found quite favourable; a maximum removal of 75.3% was obtained at 50 mg L‐1 metal concentration and a pH of 6.5 at 30°C. Dynamic modelling of the nickel uptake has been worked out and found to be of the first order. The rate constant was found to be 9.21 x 10‐1 min‐1 under the above optimum conditions of the experiment. Coefficients of the mass transfer and intraparticle diffusion were also evaluated and found to be 2.8 x 10‐2 cm s‐1 and 4.50 x 10‐2 cm2 s‐1 respectively. Langmuir's model was used for the equilibrium modelling and the constants were calculated at 30, 40 and 50°C. Thermodynamic study at different temperatures was undertaken and the values of change in the standard free energy (?G°), enthalpy (?H°) and entropy (?S°) are reported. Low temperature and high pH favour the removal of nickel (II) by adsorption on China clay.

Metal-induced inhibition of photosynthetic electron transport chain of the cyanobacterium Nostoc muscorum

Abstract: This study presents information on the mechanism of inhibition of the photosynthetic electron transport of Nostoc muscorum by chromium (Cr) and lead (Pb). Photosystem II (PS II) was found to be more sensitive both to low and high concentrations of test metals used. A considerable inhibition of photosystem I (PS I) was, however, observed at high concentrations only. Although Cr-induced inhibition of DCPIP photoreduction and lowering of chlorophyll a (Chl a) fluorescence intensity (F685) could not be reversed by artificial electron donors (diphenyl-carbazide (DPC), NH2OH, MnCl2 and benzidine) of PS II, these electron donors did substantially reverse the Pb-induced inhibition of DCPIP photoreduction as well as the lowering of Chl a fluorescence. Nevertheless, an increase in Chl a fluorescence at high concentrations of Pb suggested that this metal also arrests electron flow on the reducing side of the PS II reaction centre. Besides this, the suppression of fluorescence intensity of phycocyanin at low concentrations of both metals points to the involvement of phycobilisomes in the inhibition of PS II activity. The present study demonstrates that the modes of action of Cr and Pb on PS II are quite different.

Nitrogen and Phosphorus Removal-capacity of Four Chosen Aquatic Macrophytes in Tropical Freshwater Ponds

Abstract: The nutrient removal-capacity of four chosen aquatic macrophytes was tested in both natural and laboratory conditions. Laboratory experiments were performed under controlled conditions using ‘microcosm’ methods wherein the plants were grown in three different nutrient concentrations. For field experiments, three ponds were selected that had different levels of plant nutrient concentrations and accordingly were treated as polluted, moderately polluted, and relatively unpolluted, respectively, the object being to study the nutrient removal-capacity of chosen aquatic macrophytes living in ‘natural’ conditions. For the present investigation, four common and widespread aquatic plants growing in all three ponds were chosen: Water-hyacinth (Eichhornia crassipes [Mart.] Solms), Water-lettuce (Pistia stratiotes L.), Round-leafed Water-fern (Salvinia rotundifolia Willd.), and Lesser Duckweed (Lemna minor L.). These plants were selected also because of their frequent presence in aquatic bodies in the region and their high reproductive capacity.From the results it is revealed that, during the summer and rainy seasons, the highest content of nitrogen was removed by the Eichhornia, followed by the Pistia > Lemna > Salvinia, while during winter the highest content of nitrogen was removed by the Eichhornia followed by the Lemna > Pistia > Salvinia. Higher phosphorus removal was found in summer than in the rainy or the winter season. Phosphorus removal by the macrophytes was in the order of the Eichhornia > Pistia > Lemna > Salvinia, during the summer and rainy seasons, whereas the highest content of phosphorus was removed by Lemna in the winter months.The nutrient removal-capacity was rated to be highest by the Water-hyacinth, followed by the Pistia, then the Lemna, and lowest by the Salvinia. It was also evident that the nutrient removal increased with increasing nutrient concentration in the wastewater. The removal of nitrate by the selected macrophytes ranged from 42.0% to 96.2%, while phosphate removal ranged from 36.3% to 70.2%. A positive and significant correlation was obtained between the concentration of nitrate and phosphate in the waters and plant tissues that were studied, and it is thought that a useful strategy to employ might be to grow the Eichhornia and the Lemna together at least where winter temperatures were likely to be low enough to favour the Lemna at that season, though at other times it is apt to be a nuisance.

Mass transfer effects on the flow past an exponentially accelerated vertical plate with constant heat flux

Abstract: An analytical study is performed to examine the mass-transfer characteristics on the free-convection flow of an incompressible viscous fluid past an exponentially accelerated infinite vertical plate under the action of constant heat flux. The effects of various parameters occurring into the problem, is extensively discussed.

Impact of anaemia prophylaxis in pregnancy on maternal haemoglobin, serum ferritin & birth weight.

Abstract: 137 pregnant women treated for 100 days with 60 mg iron (as ferrous S04) and 500 mcg folic acid were compared to 123 controls from rural Varanasi District Uttar Pradesh State India as to maternal hemoglobin ferritin and birth weights in 1987-1988. Women entered the study at 16-24 weeks gestation and height weight arm circumference serum hemoglobin and serum ferritin determined by radioimmunoassay were documented. Those with hemoglobin <7.0 g/dl were referred to hospital and excluded. An estimated <10% of study and controls received the government supplement for 25-30 days. Initially the 2 groups did not differ in height weight arm circumference or hemoglobin which averaged 10.1 and 10.3 g/dl. After supplementation hemoglobin in the study group rose to an average of 12.1 and ferritin rose from 9.96 to 30.53 mcg/l (p<0.001). Mean birth weights were significantly higher in the treated group 3.88 vs. 2.59 kg with birth weights over 3.0 in 54%. The percentage of low birth weight infants (<2.5 kg) was 20.4 in the treated vs. 37.9 in the control pairs. The proportion of low birth weight infants was lower when supplementation was begun earlier at 16-19 weeks gestation. Birth weights were significantly correlated with both initial maternal weight and with the increase in hemoglobin achieved by treatment.

MHD free-convection and mass-transform flow through a porous medium

Abstract: The effect of a uniform transverse magnetic field on the free-convection and mass-transform flow of an electrically-conducting fluid past an infinite vertical plate for uniformly accelerated motion of the plate through a porous medium is discussed. The magnetic lines of force are assumed to be fixed relative to the plate. Expression for the velocity field and skin-friction are obtained by the Laplace transform technique. The influence of the various parameters, entering into the problem, on the velocity field and skin-friction is extensively discussed.

Some cosmological models with constant deceleration parameter

Abstract: Berman (1983) presented a law of variation of Hubble’s parameter that yields constant deceleration parameter models of the Universe. In this paper, Robertson-Walker models have been studied in Einstein’s theory with cosmological term and in cosmological theory based on Lyra’s geometry. Some simple models have been obtained. The necessary relations in each model have been derived, considering a perfect fluid.

The need for formulation of Shilajit by its isolated active constituents

Abstract: Shilajit, a panacea of oriental medicine, collected from different countries, exhibits overtly different levels of bioactivity. The effects of shilajit, collected from India, Nepal, Pakistan and Soviet Russia, and the effects of organic constituents isolated from a potent shilajit sample, were studied in a number of antistress and CNS activity paradigms. Shilajit from Kumaon (India), Dolpa (Nepal), and a combintion (1:1) of the total ethylacetate extracts (TE) and fulvic acids (FAs), from Kumaon shilajit, produced statistically significant effects in forced swimming-induced immobility in albino mice; restraint stress and aspirin-induced gastric ulcers in pylorus ligated albino rats; and augmented the learning acquisition and memory retention in old rats. The potential risk of ingesting shilajit, in the native form as a ‘health product’, was appraised in view of its high stable free radical content and possible contamination with mycotoxin-producing fungi. Hence, there is an imperative need for formulation of shilajit on the basis of its isolated active constituents (TE and FAs). Additionally, the physical and spectral characteristics of active FAs (bioactivity-directed) were determined and compared with those of less active and inactive samples. These would provide predictability for selection of FAs for formulation of shilajit.

Low-cycle fatigue behavior of NIMONIC PE16 at room temperature

Abstract: The fatigue behavior of NIMONIC PE16 has been investigated at room temperature as a function of γ′ particle size (from 10 to 30 nm) and total strain amplitude (0.44 to 2.60 pct). All specimens initially harden and then soften on further deformation. The degrees of hardening and softening show a marked variation with γ′ particle size and strain amplitude. Cyclic stress-strain and Coffin-Manson plots show a bilinear behavior with a change of slope at Δep/2, the plastic strain amplitude, of about 0.3 pct. These results are interpreted in terms of microstructural observations, namely, the number of slip systems activated and mutual interaction of dislocations on these systems, as well as their interaction with γ′ particles.

Dynamics of soil biomass C, N, and P in a dry tropical forest in India

Abstract: Three dry tropical forest soils along a topographic sequence were examined to determine the seasonal dynamics of microbial C, N, and P. The lowest microbial biomass was found in forest soils at the foot of the hill followed by midslope forest soils. The hilltop soil, which had the most fine particles, water-holding capacity, organic C, and total N, reflected the presence of greater amounts of microbial C, N, and P. Mean annual microbial C, N, and P ranges were 466–662, 48–72 to 21–30 μg g-1, respectively. The seasonal pattern of microbial biomass, C, N, and P was similar at all sites, the values being greatest during the dry season and lowest during the wet season. The seasonal values for microbial biomass C, N, and P were positively correlated with each other and a negative correlation was found between microbial biomass and the fine root mass in these forest soils.