Interrelations of micro-organisms and mulberry II. Phyllosphere microflora and nitrogen fixation in leaf and root surfaces

The mulberry leaves were shown to harbour substantial populations of bacteria, streptomycetes, yeasts, and moulds. Azotobacter and Beijerinckia were observed to contribute to nearly 5 to 10 per cent of the bacterial population. When grown in water culture under sterile conditions, Azotobacter inoculation on the leaf or root surface was found to increase plant growth, dry wt, and nitrogen content of the mulberry. The beneficial effect of Azotobacter was largely influenced by the presence of a carbon source in the plant nutrient solution. The root inoculation in comparison to leaf application was found to confer greater benefits to the growing plant. The presence of carbohydrates and amino acids in the leaf leachates of mulberry was shown. The mutual beneficial nature of the association of the plant and Azotobacter has been brought to light.

A Study of Practical Biological Phantoms with Simple Instrumentation for Electrical Impedance Tomography (EIT)

16-electrode phantoms are developed and studied with a simple instrumentation developed for Electrical Impedance Tomography. An analog instrumentation is developed with a sinusoidal current generator and signal conditioner circuit. Current generator is developed withmodified Howland constant current source fed by a voltage controlled oscillator and the signal conditioner circuit consisting of an instrumentation amplifier and a narrow band pass filter. Electronic hardware is connected to the electrodes through a DIP switch based multiplexer module. Phantoms with different electrode size and position are developed and the EIT forward problem is studied using the forward solver. A low frequency low magnitude sinusoidal current is injected to the surface electrodes surrounding the phantom boundary and the differential potential is measured by a digital multimeter. Comparing measured potential with the simulated data it is intended to reduce the measurement error and an optimum phantom geometry is suggested. Result shows that the common mode electrode reduces the common mode error of the EIT electronics and reduces the error potential in the measured data. Differential potential is reduced up to 67 mV at the voltage electrode pair opposite to the current electrodes. Offset potential is measured and subtracted from the measured data for further correction. It is noticed that the potential data pattern depends on the electrode width and the optimum electrode width is suggested. It is also observed that measured potential becomes acceptable with a 20 mm solution column above and below the electrode array level.

New benzidine procedure for determination of manganese in biological samples

A simple and accurate method for the determination of 0.25 to 1.0 μg. of manganese (in samples containing 1 to 4 μg. of manganese) has been developed by modifying the conditions for the reaction between permanganate and benzidine. Manganese is oxidized with potassium periodate in orthophosphoric acid and selectively estimated in the presence of excess oxidant with benzidine in formic acid. The procedure is applicable for estimation of manganese in biological samples, with recoveries in the range 97.5 to 106.1%.

Adhesion of Acidithiobacillus ferrooxidans to mineral surfaces

Direct contact mechanism in bioleaching implies prior mineral adhesion of Acidithiobacillus ferrooxidans and subsequent enzymatic attack.Prior bacterial adaptation to sulfide mineral substrates influences bacterial ferrous ion oxidation rates. It is highly beneficial to understand major biooxidation mechanisms with reference to solution- and mineral-grown cells in order to optimize bioleaching reactions. For A. ferrooxidans grown in the presence of solid substrates such as sulfur, pyrite and chalcopyrite, bacterial adhesion is required for its enzymatic machinery to come into close contact for mineral dissolution.But when grown in solution substrate such as ferrous ions and thiosulfate, such an adhesion machinery is not required for substrate utilization. Proteinaceous compounds were observed on the surface of sulfur-grown cells. Such an induction of relatively hydrophobic proteins and down regulation of exposed polysaccharides leads to changes in cell surface chemistry. Sulfur-grown and pyrite- and chalcopyrite-grown bacterial cells were found to be more efficient in the bioleaching of chalcopyrite than those grown in the presence of ferrous ions and thiosulfate. (C) 2010 Elsevier B.V. All rights reserved.

Interaction of heterocyclic thiols/thiones eliminated from cephalosporins with iodine and its biological implications

Hydrolysis of beta-lactam antibiotics by beta-lactamases (e. g., metallo-beta-lactamase, m beta l) is one of the major bacterial defense systems. These enzymes can catalyze the hydrolysis of a variety of antibiotics including the latest generation of cephalosporins, cephamycins and imipenem. It is shown in this paper that the thiol/thione moieties eliminated from certain cephalosporins by m beta l-mediated hydrolysis readily react with molecular iodine to produce ionic compounds having S-I bonds. While the reaction of MTT with iodine produced the corresponding disulfide, MDT and DMETT produced the charge-transfer complexes MDT-I-2 and DMETT-I-2, respectively. Addition of two equivalents of I-2 to MDT produced a novel cationic complex having an almost linear S-I+-S moiety and I-5(-) counter anion.However, this reaction appears to be highly solvent dependent. When the reaction of MDT with I2 was carried out in water, the reaction produced a monocation having I-5(-), indicating the reactivity of MDT toward I2 is very similar to that of the most commonly used antithyroid drug methimazole (MMI). In contrast to MMI, MDT and DMETT, the triazine-based compound MTDT acts as a weak donor toward iodine. (C)2010 Elsevier Ltd. All rights reserved.

ErbB-2 expression and its association with other biological parameters of breast cancer among Indian women

Overexpression of the epidermal growth factor receptor family genes, which include ErbB-1, 2, 3 and 4, has been implicated in a number of cancers. We have studied the extent of ErbB-2 overexpression among Indian women with sporadic breast cancer. Methods: Immmunohistochemistry and genomic polymerase chain reaction (PCR) were used to study the ErbB2 overexpression. ErbB2 status was correlated with other clinico-pathological parameters, including patient survival. Results: ErbB-2 overexpression was detected in 43.2% (159/368) of the cases by immunohistochemistry. For a sub-set of patients (n = 55) for whom total DNA was available, ErbB-2 gene amplification was detected in 25.5% (14/55) of the cases by genomic PCR. While the ErbB2 overexpression was significantly higher in patients with lymphnode (χ2 = 12.06, P≤ 0.001), larger tumor size (χ2 = 8.22, P = 0.042) and ductal carcinoma (χ2 = 15.42, P ≤ 0.001), it was lower in patients with disease-free survival (χ2 = 22.13, P ≤ 0.001). Survival analysis on a sub-set of patients for whom survival data were available (n = 179) revealed that ErbB-2 status (χ2 =25.94, P ≤ 0.001), lymphnode status (χ2 = 12.68, P ≤ 0.001), distant metastasis (χ2 = 19.49, P ≤ 0.001) and stage of the disease (χ2 = 28.04, P ≤0.001) were markers of poor prognosis. Conclusions: ErbB-2 overexpression was significantly greater compared with the Western literature, but comparable to other Indian studies. Significant correlation was found between ErbB-2 status and lymphnode status, tumor size and ductal carcinoma. ErbB-2 status, lymph node status, distant metastasis and stage of the disease were found to be prognostic indicators.

Can biological motion be a biometric?

Biological motion has successfully been used for analysis of a person's mood and other psychological traits. Efforts are made to use human gait as a non-invasive mode of biometric. In this reported work, we try to study the effectiveness of biological gait motion of people as a cue to biometric based person recognition. The data is 3D in nature and, hence, has more information with itself than the cues obtained from video-based gait patterns. The high accuracies of person recognition using a simple linear model of data representation and simple neighborhood based classfiers, suggest that it is the nature of the data which is more important than the recognition scheme employed.

Surface modifications in single crystal surfaces of YBa2Cu3O7-delta upon high energy ion irradiation

Atomic force microscopy investigations on swift heavy ion (200 MeV An) irradiated surfaces of a high T-c single crystal YBa2Cu3O7-delta are presented. Results obtained revealed an ion-induced erosion/sputtering clearly confirming our earlier observation on grain boundary dominated thin films. Apart from sputtering, notable effects were seen with many defect structures like dikes/hillocks surrounded by craters, dikes, holes, pearl like structures and ripple formation of sub-micron undulations, all in one crystal. Results are discussed in the light of co-operative phenomena of material re-distribution mechanism related to mass transfer and crater formations.

Darcian mixed convection plumes along vertical adiabatic surfaces in a saturated porous medium

The mixed convection flow due to a line thermal source embedded at the leading edge of an adiabatic vertical plane surface immersed in a saturated porous medium has been studied. Both weakly and strongly buoyant plume regimes have been considered. The cases of buoyancy assisting and buoyancy opposing flow conditions have been incorporated in the analysis. The results are presented for the entire range of buoyancy parameter from the pure forced convection (xgr=0) to the pure free convection (xgr rarr infin@#@) regimes. For buoyancy-assisting flow, the wall temperature and the velocity at the wall increase as the plume strength increases. However, they all decrease as the free-stream velocity increases. For buoyancyopposing flow, the temperature at the wall increases as the strength of the plume increases but velocity at the wall decreases.