935 research outputs found

    Paramagnetic magnetization signals and curious metastable behaviour in field-cooled magnetization of a single crystal of superconductor 2H-NbSe2

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    We present here some newer characteristics pertaining to paramagnetic Meissner effect like response in a single crystal of the low Tc superconducting compound 2H-NbSe2 via a detailed study of effects of perturbation on the field-cooled magnetization response. In the temperature range, where an anomalous paramagnetic magnetization occurs, the field-cooled magnetization response is found to be highly metastable: it displays a curious tendency to switch randomly from a given paramagnetic value to a diamagnetic or to a different paramagnetic value, when the system is perturbed by an impulse of an externally applied ac field. The new facets revealed in a single crystal of 2H-NbSe2 surprisingly bear a marked resemblance with the characteristics of magnetization behaviour anticipated for the giant vortex states with multiple flux quanta predicted to occur in mesoscopic-sized superconducting specimen and possible transitions amongst such states.Comment: 12 pages, 9 figures, submitted to Journal of Physics: Condensed Matte

    Estimation and Correction of RF Impairments in LTE Downlink

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    This Work focuses on refining the received signal at mobile receiver in 4G-LTE mobile communication. Impairments Such as Carrier Frequency Offset, Sampling Frequency offset , DC Offset and IQ Imbalance are studied and some possible ways to overcome those problems has discussed. Simulations are done in Matlab to verify algorithms to correct those impairments. They are also tested on received signals from some of the Test Equipments. Soft Demapping of 16 and 64 QAM is discussed,a simplified approach to demodulate symbols has been presented. Also Channel Estimation and Interpolation techniques are discussed

    Photocatalytic activity of mixed-phase of TiO2 synthesized by non-aqueous methodology

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    768-774A mix-phase (anatase-rutile) nanocrystalline titania particles were successfully synthesized in a non-aqueous solvent medium using a novel approach of controlled hydrolysis of titanium isopropoxide. The hydrolysis was carried out by the controlled release of water molecules from simple Schiff base formation reaction of anisaldehyde employing aniline as an amine component in isopropanol solvent medium. The excess aniline used, and the imine formed acts as directing agents. The photocatalytic activities of the catalysts prepared were compared with Degussa P25 for methylene blue degradation in direct sunlight. The photocatalytic activity was found to increase with decreasing availability of water molecules formed during the Schiff base formation (imination) reaction. Also, it was found to affect the phase and shape selection. TEM images show sphere-like to hexagonal to a rod-shaped formation of particulates

    Assessment of Maximum Bite Force in Oral Submucous Fibrosis Patients: A Preliminary Study

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    Objective: To determine the maximum bite force (MBF) in oral submucous fibrosis (OSMF) patients and to compare them with that of healthy subjects. Material and Methods: Twenty patients who were clinically confirmed, as OSMF and 20 healthy controls matched for age, gender, and number of intact functional teeth were included in this study. For each subject, age, gender, weight, height and body mass index (BMI) were recorded. The MBF registration was carried out by the two evaluators, who were previously calibrated. Bite force was measured in the first molar region using a force transducer occlusal force meter for each subject seated at the upright position, with Frankfort's plane nearly parallel to the floor, and no head support. The Student’s independent t-test was used to determine the statistical significance in relation to mean height, weight, BMI and the presence of number of intact teeth and MBF between the healthy subjects and OSMF individuals. A comparison of grades of OSMF with all variables was carried out by one-way ANOVA test. Results: No significant difference was found in mean age, mean height, weight, BMI and the presence of the number of intact teeth between healthy individuals and OSMF patients. The mean MBF in healthy subjects was 628.23 ± 24.39 N and 635.47 ± 31.22 N in OSMF patients. Even though the healthy subjects reported a higher MBF than OSMF patients did, the difference was statistically non-significant. With regards to sides, no significant difference was observed in mean MBF in healthy subjects and OSMF patients on the right (p=0.7818) and left side (p=0.6154). Conclusion: The healthy subjects reported higher MBF values than OSMF patients did and the difference was statistically non-significant

    Comparison of the Structural Stability and Dynamic Properties of Recombinant Anthrax Protective Antigen and its 2- Fluorohistidine Labeled Analogue

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    Protective antigen (PA) is the primary protein antigenic component of both the currently used anthrax vaccine and related recombinant vaccines under development. An analogue of recombinant PA (2-FHis rPA) has been recently shown to block the key steps of pore formation in the process of inducing cytotoxicity in cells, and thus can potentially be used as an antitoxin or a vaccine. This rPA analogue was produced by fermentation to incorporate the unnatural amino acid 2-fluorohistidine (2-FHis). In this study, the effects of 2-FHis labeling on rPA antigen’s conformational stability and dynamic properties were investigated by various biophysical techniques. Temperature/pH stability profiles of rPA and 2-FHis rPA were analyzed by the empirical phase diagram (EPD) approach, and physical stability differences between them were identified. Results showed that rPA and 2-FHis rPA had similar stability at pH 7–8. With decreasing solution pH, however, 2-FHis rPA was found to be more stable. Dynamic sensitive measurements of the two proteins at pH 5 found that 2-FHis rPA was more dynamic and/or differentially hydrated under acidic pH conditions. The biophysical characterization and stability data provide information useful for the potential development of 2-FHis rPA as a more stable rPA vaccine candidate

    Technical Paper Session I-B - CIGSeS and CIGS2 Thin Film Solar Cells on Flexible Foils for Space Power

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    The objective of the research is to develop flexible, lightweight, radiationresistant, high-specific-power, highly efficient CuIn1-xGaxSe2-ySy (CIGSeS) and CuIn1- xGaxS2 (CIGS2) thin-film solar cells for space electric power. The near optimum bandgap, potential for higher specific power, and superior radiation resistance make this technology an ideal candidate for space electric power. The superior radiation resistance of CIGSeS thin-film solar cells relative to the conventional silicon and gallium arsenide single-crystal cells in the space radiation environment would extend mission lifetimes substantially. The conventional rigid Si and GaAs cells must be folded in an accordion style for deployment space. This can cause problems of opening up and folding of the solar array as has happened recently with the International Space Station. On the other hand, the flexible solar cells and modules can be packaged and rolled out more easily. The stainless steel and titanium foil substrate materials are capable of withstanding high temperatures required for preparing good quality CIGSeS absorber layer. They also do not sag easily and hence do not require rigidizing as is the case with plastic sheet substrates. The CIGSeS absorber film is prepared by selenization/sulfurization of DC magnetron sputter-deposited CuGa, In metallic precursors on 10 cm x 10 cm metallic foil substrate coated with molybdenum back contact layer. CdS heterojunction partner is deposited by chemical bath deposition. Transparent and conducting bilayer of intrinsic ZnO and aluminum doped ZnO:Al is deposited by RF magnetron sputtering. Cells are completed by depositing Ni/Al front contact fingers by thermal evaporation. The sputtering technique utilized in the preparation of solar cells provides an added advantage of facilitating easy scale-up of the laboratory size cells for economic large-area manufacture by the roll-to-roll process. Chemical composition, crystallographic structure and morphology of CIGSeS thin films are analyzed by energy dispersive spectroscopy, Auger electron spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The photovoltaic properties of completed cells are studied by measurement of current-voltage characteristics and quantum efficiency. Best efficiencies of 10.4% under AM 1.5 conditions and 8.84% under AM 0 conditions were achieved on small-area CIGS2 thin-film solar cells

    Noise Mapping and Variance of Road Traffic Noise: Identification of Most Noise Impacting Vehicular Type in an Urban Region

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    Urban road traffic noise is a major concern in developing as well as developed countries. Often it is difficult to identify the most noise impacting vehicular type especially in urban region with mixed vehicular flow. Herein, we analysed in a systematic way to identify the most noise impacting vehicular type at Hyderabad city of India. The road traffic noise across the corridor-3 metro line known as the blue line metro was chosen in the present study because, it stretches from north to south connecting 23 stations comprising major residential and commercial locations of the city. The noise levels were analysed as per CPCB guidelines. The noise pollution quantifying parameters such as Noise Climate (NC), Noise Pollution Level (LNP), and Traffic Noise Index (TNI) were analysed across the lane. A systematic analysis revealed that, the twowheelers are the most noise impacting vehicles in the daytime whereas four-wheelers in the nighttime. Noise map generated using the IDW spatial interpolation method shows the noise impacted regions across the metro lane stretching ~27 km of the city. The methodological pattern in the present investigation can be useful tool in identifying the most noise impacting vehicular type in any region with a mixed vehicular flow

    Conductance Distributions in Chaotic Mesoscopic Cavities

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    We consider the conductance distributions in chaotic mesoscopic cavities for all three invariant classes of random matrices for the arbitrary number of channels N1, N2 in the connecting leads. We show that the Laplace transforms of the distributions can be expressed in terms of determinants in the unitary case and Pfaffians in the orthogonal and symplectic cases. The inverse Laplace transforms then give the exact distributions. This formalism is particularly useful for small values of N = min (N1, N2), and thus is of direct experimental relevance. We also obtain the conductance distributions for orthogonal-unitary and symplectic-unitary crossover ensembles.Comment: 19 pages, 4 figure
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