Indigenous development of ultra high vacuum (UHV) magnetron sputtering system for the preparation of Permalloy magnetic thin films

We have designed and developed an indigenous ultra high vacuum (UHV) sputtering system which can deposit magnetic thin films with high purity and good uniformity. The equipment consists of state-of the-art technologies and sophistication. With this system it is possible to deposit coatings of various materials on a sample size of 3”3” 3”. The Ni81Fe19 ferromagnetic thin films, with Tantalum (Ta) as a buffer and cap layers have been deposited on silicon substrates using this ultra high vacuum (UHV) sputtering system. The magneto transport measurement study indicated a significant variation in the AMR values of the films for varying thicknesses of tantalum and NiFe layers

Investigation of interface properties of sputter deposited TiN/CrN superlattices by low-angle X-ray reflectivity

Approximately 1.8 m thick nanolayered multilayer coatings of TiN/CrN (also known as superlattices) were deposited on silicon (100) substrates at different modulation wavelengths (4.6–12.8 nm), substrate temperatures (50-400 °C) and substrate bias voltages (-50 to -200 V) using a reactive direct current magnetron sputtering system. X-ray reflectivity (XRR) technique was employed to determine various properties of the multilayers such as interface roughness, surface roughness, electron density, critical angle and individual layer thicknesses. The modulation wavelengths of the TiN/CrN superlattice coatings were calculated using modified Bragg’s law. Furthermore, the experimental X-ray reflectivity patterns were simulated using theoretically generated patterns and a good fit was obtained for a three layer model, i.e., (1) top surface roughness layer, (2) TiN/CrN multilayer coating (approximately 1.8 m) and (3) Ti interlayer (~ 0.5 m) at the film-substrate interface. For the superlattice coatings prepared at a modulation wavelength of 9.7 nm, a substrate bias of -200 V and a substrate temperature of 400 C the XRR patterns showed Bragg reflections up to 5th order, indicating well-defined periodicity of the constituent layers and relatively sharp interfaces. The simulation showed that the superlattice coatings prepared under the above conditions exhibited low surface and interface roughnesses. We also present the effect of substrate temperature and substrate bias, which are critical parameters for controlling the superlattice properties, onto the various interface properties of TiN/CrN superlattices

Optical and anti-oxidant application of zinc doped cadmium sulfide nanoparticle

9-17Present work explains about optical and oxidant activity of zinc doped cadmium sulfide nanoparticle. Compare with undoped cadmium sulfide, zinc doped nanoparticles have different results in IR, SEM, TEM and XRD. EDAX image shows the crystalline arrangement of nanoparticles. Anti-oxidant activity describes using DHHP’s radical scavenging method and optical relation determine by Tauc’s equation

Service Control in a Retrial Service Facility System with Two-type of Customer-Semi MDP

In the literature on service facility system, it is common to assume fixed service rate, such as flexible retrial arrival, this assumption is not realistic. In contrast retrial demands model rarely define the mechanism through which arrival of customers is classified into two types say priority customers and ordinary customers. For the given values of maximum inventory, maximum waiting space, reorder level and lead times, we determine the optimal ordering policy at various instants of time. The system is formulated as a Semi-Markov Decision Process and the optimum policy to be employed is found using linear programming method. Numerical examples are provided to illustrate the model

Oxidant-Antioxidant disturbance in men classified as obese according to the preliminary WHO guidelines for Asians

Background: Though there are experimental and clinical evidences regarding oxidant-antioxidant disturbance in obese subjects, clinical data supporting the same in Indian male subjects is lacking. The objective of the present study was to verify the oxidative stress status of male subjects classified as obese according to the WHO guidelines for Asians.Methods: Thirty six obese men with BMI between 25-30 Kg/m2 and 30 non-obese men with BMI < 25 Kg/m2 were enrolled in the study. Malondialdehyde, reduced glutathione, glutathione peroxidase, catalase, fasting glucose and body mass index were assessed in both the groups.Results: Plasma MDA and erythrocyte activity of glutathione peroxidase were significantly increased in the obese subjects when compared with controls. The levels of reduced glutathione were significantly reduced in the obese group when compared with controls. Among the obese group, BMI was significantly associated with MDA and glutathione peroxidase. Further among the obese subjects, glutathione peroxidase correlated significantly with MDA. A significant negative correlation was obtained between MDA and GSH in obese subjects.Conclusion: The data from the present study indicates a significant perturbation of the oxidant – antioxidant status in Indian males considered as obese according to the preliminary WHO guidelines for Asians. The increase in oxidative stress and glutathione peroxidase activity in obesity may contribute towards its pathological complications

Gunn Effect in Silicon Nanowires: Charge Transport under High Electric Field

Gunn (or Gunn-Hilsum) Effect and its associated negative differential resistivity (NDR) emanates from transfer of electrons between two different energy bands in a semiconductor. If applying a voltage (electric field) transfers electrons from an energy sub band of a low effective mass to a second one with higher effective mass, then the current drops. This manifests itself as a negative slope or NDR in the I-V characteristics of the device which is in essence due to the reduction of electron mobility. Recalling that mobility is inversely proportional to electron effective mass or curvature of the energy sub band. This effect was observed in semiconductors like GaAs which has direct bandgap of very low effective mass and its second indirect sub band is about 300 meV above the former. More importantly a self-repeating oscillation of spatially accumulated charge carriers along the transport direction occurs which is the artifact of NDR, a process which is called Gunn oscillation and was observed by J. B. Gunn. In sharp contrast to GaAs, bulk silicon has a very high energy spacing (~1 eV) which renders the initiation of transfer-induced NDR unobservable. Using Density Functional Theory (DFT), semi-empirical 10 orbital ($sp^{3}d^{5}s^{*}$) Tight Binding (TB) method and Ensemble Monte Carlo (EMC) simulations we show for the first time that (a) Gunn Effect can be induced in narrow silicon nanowires with diameters of 3.1 nm under 3 % tensile strain and an electric field of 5000 V/cm, (b) the onset of NDR in I-V characteristics is reversibly adjustable by strain and (c) strain can modulate the value of resistivity by a factor 2.3 for SiNWs of normal I-V characteristics i.e. those without NDR. These observations are promising for applications of SiNWs in electromechanical sensors and adjustable microwave oscillators.Comment: 18 pages, 6 figures, 63 reference

In vitro susceptibility of clinical isolates of Mycobacterium tuberculosis to cefadroxil—a cephalosporin antibiotic

The bactericidal activity (BA) of cefadroxil, a semisynthetic cephalosporin antibiotic, against M. tuberculosis H37Rv was studied in Middlebrook 7H9 medium, Cefadroxil showed good BA (average fall of viable counts = log10 0.32 colony forming units/ml/day) against the log phase culture of M. tuberculosis H37Rv. Its minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were found to be 15 μg/ml or less. The MIC of cefadroxil for 29 clinical isolates of M. tuberculosis and a laboratory strain, M. tuberculosis H37Rv was also determined by agar dilution method using Middlebrook 7H11 agar as a screening procedure. The MIC of cefadroxil was found to be 10 μg/ml or less for M. tuberculosis H37Rv and 16 (55.1%) of 29 clinical isolates tested. The MIC for 3 of 10 drug sensitive and 9 of 19 drug resistant isolates was 40 or more, a concentration much higher than the peak plasma concentration (28 μg/ml) attained in human beings. The higher MIC observed in 12 of 29 clinical isolates irrespective of their susceptibility pattern requires further studies to assess the usefulness of cefadroxil in the treatment of tuberculosis

Optical and anti-oxidant application of zinc doped cadmium sulfide nanoparticle

Present work explains about optical and oxidant activity of zinc doped cadmium sulfide nanoparticle. Compare with undoped cadmium sulfide, zinc doped nanoparticles have different results in IR, SEM, TEM and XRD. EDAX image shows the crystalline arrangement of nanoparticles. Anti-oxidant activity describes using DHHP’s radical scavenging method and optical relation determine by Tauc’s equation

Isolation of mycobacterium tuberculosis from cerebrospinal fluid by the centrifugation and filtration methods

Cerebrospinal fluid (CSF) samples were collected in 2 bottles each, from 112 children, examined clinically for tuberculous meningitis (TBM). One was processed by the centrifugation method and the other by the filtration method for the isolation of M. tuberculosis. Of these specimens, 11 and 13 yielded M. tuberculosis by the centrifugation method and the filtration method, respectively. In 7 specimens M. tuberculosis was isolated by both the methods; in 4, only by the centrifugation method, and in 6, only by the filtration method. Using both the methods, 17 (15.2%) of 112 specimens were culture positive for M. tuberculosis. The improvement in the rate of isolation, thus obtained, assumes importance as the confirmation of the diagnosis of TBM in all the clinically suspected cases is always desired. Moreover, the filtration method is simple and inexpensive and it can be carried out even in remote hospitals and the membranes, after filtration, can be transported to central mycobacteriology laboratory for culture of tubercle bacilli