Design, development and performance study of six-gap glass MRPC detectors

The Multigap Resistive Plate Chambers (MRPCs) are gas ionization detectors with multiple gas sub-gaps made of resistive electrodes. The high voltage (HV) is applied on the outer surfaces of outermost resistive plates only, while the interior plates are left electrically floating. The presence of multiple narrow sub--gaps with high electric field results in faster signals on the outer electrodes, thus improving the detector's time resolution. Due to their excellent performance and relatively low cost, the MRPC detector has found potential application in Time-of-Flight (TOF) systems. Here we present the design, fabrication, optimization of the operating parameters such as the HV, the gas mixture composition, and, performance of six--gap glass MRPC detectors of area 27cm $\times$ 27 cm, which are developed in order to find application as trigger detectors, in TOF measurement etc. The design has been optimized with unique spacers and blockers to ensure a proper gas flow through the narrow sub-gaps, which are 250 $\mu$m wide. The gas mixture consisting of R134A, Isobutane and SF$_{6}$, and the fraction of each constituting gases has been optimized after studying the MRPC performance for a set of different concentrations. The counting efficiency of the MRPC is about 95% at $17.9$ kV. At the same operating voltage, the time resolution, after correcting for the walk effect, is found to be about $219$ ps.Comment: Revised version with 15 pages, 14 figures, 2 tables. Accepted for publication in the European Physical Journal

Hall effect in cobalt-doped TiO2−δ_{2-\delta}

We report Hall effect measurements on thin films of cobalt-doped TiO$_{2-\delta}$. Films with low carrier concentrations (10$^{18}$ - 10$^{19}$) yield a linear behavior in the Hall data while those having higher carrier concentrations (10$^{21}$ - 10$^{22}$) display anomalous behavior near zero field. In the entire range of carrier concentration, n-type conduction is observed. The appearance of the anomalous behavior is accompanied by a possible structural change from rutile TiO$_{2}$ to Ti_[n}O$_{2n-1}$ Magneli phase(s)

Immunoadjuvant potential of Azadirachta indica, Butea frondosa and Ficus religiosa against Swine flu vaccine antigen

Introduction: In general, primary or secondary metabolites derived from medicinal plant products might be responsible for stimulating or suppressing the immune system against specific protein antigens. The objective of this study was to evaluate the adjuvant potential of aqueous leaves extract of Azadirachta indica, Butea frondosa and Ficus religiosa against Swine flu vaccine antigen.Methods: In this study, our group evaluated the antibody (IgG) titre of Swine flu vaccine antigen (2 μg/mL) using variable doses (0.625–5 mg) of aqueous leaves extract of A. indica, B. frondosa and F. religiosa. In addition, Swiss mice were immunized subcutaneously (100 μL) on day 0 with Swine flu vaccine antigen (1:1000 dilution). Splenocytes were collected on day 7 and cultured with variable doses of aqueous leaves extract of A. indica, B. frondosa and F. religiosa pertaining to determine the total cellular content and splenocyte proliferation (Swine flu vaccine; Ovalbumin, OVA and Con A) assay. In addition, estimation of Th1 (IFN-gamma and TNF alpha) cytokines in cell culture supernatant containing swine flu vaccine antigen along with aqueous leaves extract were measured.Results: Aqueous leaves extract of A. indica, B. frondosa and F. religiosa showed anti-Swine flu titre at higher doses. In ex vivo animal model studies these three medicinal plants in the form of aqueous leaves extract enhanced total cellular content at higher doses but increased in splenocyte proliferation (Swine flu vaccine, OVA and Con A) assay at lower doses. Similarly, there was enhancement in Th1 cytokines (IFN-gamma, TNF alpha) with respect to swine flu vaccine antigen containing aqueous extract at lower doses as compared to control group.Conclusion: Aqueous leaves extract of A. indica, B. frondosa and F. religiosa showed adjuvant activity against Swine flu vaccine antigen and might be used in manufacturing active adjuvant for vaccine antigen

Temperature dependent optical studies of Ti1−x_{1-x}Cox_xO2_2

We present the results of Raman and photoluminescence (PL) studies on epitaxial anatase phase Ti$_{1-x}$Co$_x$O$_2$ films for $x$ = 0-0.07, grown by pulsed laser deposition. The low doped system ($x$=0.01 and 0.02) shows a Curie temperature of ~700 K in the as-grown state. The Raman spectra from the doped and undoped films confirm their anatase phase. The photoluminescence spectrum is characterized by a broad emission from self-trapped excitons (STE) at 2.3 eV at temperatures below 120 K. This peak is characteristic of the anatase-phase TiO$_2$ and shows a small blueshift with increasing doping concentration. In addition to the emission from STE, the Co-doped samples show two emission lines at 2.77 eV and 2.94 eV that are absent in the undoped film indicative of a spin-flip energy.Comment: 8 pages, 4 figure

Influence of Glomus Species and Soil Phosphorous on Verticillium Wilt in Bt Cotton

Amendment of single superphosphate to the soil was done at 20mg /kg and 300mg /kg. After that soil was treated with different treatments like a) Verticillium dahliae, b) Glomus species, c) both Verticillium and Glomus species d) None of Glomus species and Verticillium. The Verticillium wilt was more severe in plants infected with Glomus species than non-mycorrhizal plants fertigated at 20mg P / kg of soil. However, in plants fertigated with 300mg P / kg of soil, Verticillium wilt was equally severe in mycorrhizal and non-mycorrhizal plants. More propagules of V. dahliae were found in the plants fertigated with 20mg P / kg of soil, in petioles of mycorrhizal plants than that of non-mycorrhizal plants. The plants fertigated with 300mg P / kg of soil reported maximum number of propagules of V. dahliae were not significantly different in mycorrhizal and non-mycorrhizal plants.  It was found that infection of V. dahliae in Bt cotton by Glomus species was not affected in plants fertigated with 20mg P / kg of soil.  The infection was inhibited by phosphorous and further by V. dahliae in plants fertigated with 300mg P / kg of soil.  The concentrations of phosphorous in the leaves of the treated plants were found similar to the treated mycorrhizal and non-mycorrhizal plants fertigated with 20mg P / kg of soil. The plants infected with V. dahliae alone were found lower than the plants infected with both V. dahliae and Glomus species

Superconducting MgB2 thin films by pulsed laser deposition

Growth of MgB2 thin films by pulsed laser deposition is examined under ex situ and in situ processing conditions. For the ex situ process, Boron films grown by PLD were annealed at 900 C with excess Mg. For the in situ process, different approaches involving ablation from a stoichiometric target under different growth conditions, as well as multilayer deposition involving interposed Mg layers were examined and analyzed. Magnetic measurements on ex situ processed films show TC of ~39 K, while the current best in situ films show a susceptibility transition at ~ 22 K.Comment: 3 pages, PD

Electric Field Effect in Diluted Magnetic Insulator Anatase Co:TiO2

An external electric field induced reversible modulation of room temperature magnetic moment is achieved in an epitaxial and insulating thin film of dilutely cobalt-doped anatase TiO2. This first demonstration of electric field effect in any oxide based diluted ferromagnet is realized in a high quality epitaxial heterostructure of PbZr0.2Ti0.8O3/Co:TiO2/SrRuO3 grown on (001) LaAlO3. The observed effect, which is about 15% in strength in a given heterostructure, can be modulated over several cycles. Possible mechanisms for electric field induced modulation of insulating ferromagnetism are discussed.Comment: 14 pages, 4 figure

High Temperature Phase Stability in Li0.12Na0.88NbO3: A Combined powder X-Ray and Neutron Diffraction Study

Lithium doped sodium niobate is an ecofriendly piezoelectric material that exhibits a variety of structural phase transitions with composition and temperature. We have investigated the phase stabilities of an important composition Li0.12Na0.88NbO3 (LNN12) using a combination of powder x-ray and neutron diffraction techniques in the temperature range 300 - 1100 K. Detailed Rietveld analyses of thermo-diffractograms show a variety of structural phase transitions ranging from non-polar antiferrodistortive to ferroelectric in nature. In the temperature range of 525 K to 675 K, unambiguous experimental evidence is shown for phase coexistence of orthorhombic paraelectric O1 phase (space group Cmcm) and orthorhombic ferroelectric O2 phase (space group Pmc21). The bp primitive lattice parameter of the ferroelectric orthorhombic phase (O2 phase) decreases, while the ap and cp primitive lattice parameters show normal increase with increase in temperature. Above 675 K, in the O1 phase, all lattice parameters come close to each other and increase continuously with increase of temperature, and around 925 K, ap parameter approaches bp parameter and thus the sample undergoes an orthorhombic to tetragonal phase transition. Further as temperature increases, the cp lattice parameter decreases, and finally approaches to ap parameter, and the sample transform into the cubic phase. The continuous change in the lattice parameters reveals that the successive phase transformations from orthorhombic O1 to high temperature tetragonal phase and finally to the cubic phase are not of a strong first order type in nature. We argue that application of chemical pressure as a result of Li substitution in NaNbO3 matrix, favours the freezing of zone centre phonons over the zone boundary phonons that are known to freeze in pure NaNbO3 as function of temperature.Comment: 15 pages, 5 Figures. arXiv admin note: text overlap with arXiv:1011.441