7,093 research outputs found

    Tuberculosis vaccine: pipeline approaches and future prospective

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    Tuberculosis (TB), despite anti-mycobacterial therapies and vaccine, is a deadly infectious disease with about 12 million incident cases worldwide. Existing Bacillus Calmette-Guérin (BCG) vaccine is unquestionably inexpensive, safe and effective against severe forms of childhood TB but appears to be limited in effectiveness against adult pulmonary disease in endemic areas. Genetic variation in the population is the major obstruction inhibiting validation of biomarkers for protective human immunity against TB. Since current TB cases are presenting new challenges with threats of HIV co-infection therefore various attempts at a global platform are being made to develop a new modified vaccine against it. Consequently, Modified Vaccinia Ankara virus (MVA) vectored MPT64 & Ag85A delivery and polyvalent DNA vaccine, expressing an ESAT6–Ag85B fusion protein etc. are preclinically tested for boosted immune effects. However, better vaccine approaches still need to be developed against M. tuberculosis which can be unbeaten in most infected areas

    Accelerating dark energy models in bianchi Type-V space-time

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    Some new exact solutions of Einstein's field equations in a spatially homogeneous and anisotropic Bianchi type-V space-time with minimally interaction of perfect fluid and dark energy components have been obtained. To prevail the deterministic solution we choose the scale factor a(t)=tneta(t) = \sqrt{t^{n}e^{t}}, which yields a time dependent deceleration parameter (DP), representing a model which generates a transition of the universe from the early decelerating phase to the recent accelerating phase. We find that for n1n \geq 1, the quintessence model is reproducible with present and expected future evolution of the universe. The other models (for n<1n < 1), we observe the phantom scenario. The quintessence as well as phantom models approach to isotropy at late time. For different values of nn, we can generate a class of physically viable DE models. The cosmic jerk parameter in our descended model is also found to be in good concordance with the recent data of astrophysical observations under appropriate condition. The physical and geometric properties of spatially homogeneous and anisotropic cosmological models are discussed.Comment: 12 pages, 6 figure

    Thermoelectric response of Fe1+y_{1+y}Te0.6_{0.6}Se0.4_{0.4}: evidence for strong correlation and low carrier density

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    We present a study of the Seebeck and Nernst coefficients of Fe1+y_{1+y}Te1x_{1-x}Sex_{x} extended up to 28 T. The large magnitude of the Seebeck coefficient in the optimally doped sample tracks a remarkably low normalized Fermi temperature, which, like other correlated superconductors, is only one order of magnitude larger than Tc_c. We combine our data with other experimentally measured coefficients of the system to extract a set of self-consistent parameters, which identify Fe1+y_{1+y}Te0.6_{0.6}Se0.4_{0.4} as a low-density correlated superconductor barely in the clean limit. The system is subject to strong superconducting fluctuations with a sizeable vortex Nernst signal in a wide temperature window.Comment: 4 pages including 4 figure

    Electrical properties of a lead-free perovskite ceramic: (Na0.5Sb0.5)TiO3

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    Polycrystalline (Na0.5Sb0.5)TiO3 was prepared using a high-temperature solid-state reaction method. An XRD analysis indicated the formation of a single-phase monoclinic structure. Complex impedance studies revealed the presence of grain boundary effects from 300 °C onwards. Also, the dielectric relaxation in the system was found to be of a non-Debye type. The ac conductivity data were used to evaluate the density of states at the Fermi level, the minimum hopping length and activation energy of the compound. The dc electrical and thermal conductivities of grain and grain boundary have been assessed. The correlated barrier hopping model was found to successfully explain the mechanism of charge transport in (Na0.5Sb0.5)TiO3

    Magnetic phase diagram of Fe1.1Te1-xSex: A comparative study with the stoichiometric superconducting FeTe1-xSex system

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    We report a comparative study of the series Fe1.1Te1-xSex and the stoichiometric FeTe1-xSex to bring out the difference in their magnetic, superconducting and electronic properties. The Fe1.1Te1-xSex series is found to be magnetic and its microscopic properties are elucidated through Moessbauer spectroscopy. The magnetic phase diagram of Fe1.1Te1-xSex is traced out and it shows the emergence of spin-glass state when the antiferromagnetic state is destabilized by the Se substitution. The isomer shift and quadrupolar splitting obtained from the Moessbauer spectroscopy clearly brings out the electronic differences in these two series.Comment: 6 pages, 9 figure
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