5,753 research outputs found

    Specific heat of robust Nb2PdS5 superconductor

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    We report specific heat under different magnetic fields for recently discovered quasi-one dimensional Nb2PdS5 superconductor. The studied compound is superconducting below 6 K. Nb2PdS5 is quite robust against magnetic field with dHc/dT of -42 kOe/K. The estimated upper critical field [Hc2(0)] is 190 kOe, clearly surpassing the Pauli-paramagnetic limit of 1.84Tc. Low temperature heat capacity in superconducting state of Nb2PdS5 under different magnetic fields showed s-wave superconductivity with two different gaps. Two quasi-linear slopes in Somerfield-coefficient as a function of applied magnetic field and two band behavior of the electronic heat capacity demonstrate that Nb2PdS5 is a multiband su-perconductor in weak coupling limit with deltagamma/deltaTc=0.9.Comment: 4 pages text Figs. Short Letter MS. Letter-J. Sup. & Novel Ma

    PdTe a 4.5K Type II BCS Superconductor

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    We report on the structure and physical properties of bulk Palladium Tellurium superconductor, which is synthesized via quartz vacuum encapsulation technique at 750 C. The as synthesized compound is crystallized in hexagonal crystal structure. Magnetization and Magneto-transport measurements provided the values of lower and upper critical field to be 250 and 1200 Gauss respectively at 2 Kelvin. The Coherence length and GL parameter are estimated from the experimentally determined upper and lower critical fields, which are 45 nm and 1.48 respectively. The jump in Cp(T) at Tc is found to be 1.33 and the Debye temperature and electronic specific heat constant are 203 Kelvin and 6.01mJ/mole-K2 respectively.Comment: 13 pages Text + Figs: Accepted in Sup. Sci. and Tec

    Majorization for certain classes of meromorphic functions defined by integral operator

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    Here we investigate a majorization problem involving starlike meromorphic functions of complex order belonging to a certain subclass of meromorphic univalent functions defined by an integral operator introduced recently by Lashin

    Weak ferromagnetism in non-centrosymmetric BiPd 4K superconductor

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    We report synthesis of non-centrosymmetric BiPd single crystal by self flux method. The BiPd single crystal is crystallized in monoclinic structure with the P21 space group. Detailed SEM (Scanning Electron Microscopy) results show that the crystals are formed in slab like morphology with homogenous distribution of Bi and Pd. The magnetic susceptibility measurement confirmed that the BiPd compound is superconducting below 4K. Further, BiPd exhibits weak ferromagnetism near the superconducting transition temperature in isothermal magnetization (MH) measurements. The temperature dependent electrical resistivity also confirmed that the BiPd single crystal is superconducting at Tc=4K. Magneto transport measurements showed that the estimated Hc2(0) value is around 7.0kOe. We also obtained a sharp peak in heat capacity Cp(T) measurements at below 4K due to superconducting ordering. The normalized specific-heat jump, DC/{\gamma}Tc, is 1.52, suggesting the BiPd to be an intermediate BCS coupled superconductor. The pressure dependent electrical resistivity shows the Tc decreases with increasing applied pressure and the obtained dTc/dP is -0.62K/Gpa.Comment: 11 pages Text+Fig

    A stable Algebraic Spin Liquid in a Hubbard model

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    We show the existence of a stable Algebraic Spin Liquid (ASL) phase in a Hubbard model defined on a honeycomb lattice with spin-dependent hopping that breaks time-reversal symmetry. The effective spin model is the Kitaev model for large on-site repulsion. The gaplessness of the emergent Majorana fermions is protected by the time reversal (TR) invariance of this model. We prove that the effective spin model is TR invariant in the entire Mott phase thus ensuring the stability of the ASL. The model can be physically realized in cold atom systems and we propose experimental signals of the ASL.Comment: Published in PR

    Pit Slope Failure Problems in Goan Iron Ore Mines, Goa, India

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    The problem of open pit slope stability is a matter of concern when the mining operations go deeper followed by weak strata conditions. In Goa iron ore mines the problem of slope instability has been faced by several mines, after the on-set of monsoon. A review of case studies available on the subject demonstrates that the ground displacement, stress redistribution, effect of ground water, low strength characteristics of the slope forming materials played significant role for the cause of slope failures. Slope monitoring studies indicated that the mechanism of slope failures could be complex and dependent on failure pathways, where certain units fail first and it is followed by subsequent failures due to redistribution of stresses from the preceding zone. The results of several observations, laboratory testing of slope forming materials and monitoring of the slopes have lead to an awareness of various mechanisms of failure and the conditions under which they occur. In real world situations, the failure mechanisms are much more complex involving many other variables due to complexity within the geological materials. The paper addressed the design of practical pit slope angles in such type of weak strata conditions. The testing techniques for material properties enable weak zones to be identified and their relative strengths are accurately determined. Case study of a large Iron mine discussed in detail to demonstrate how deep mining can be carried out under difficult ground conditions

    Hyperreactio luteinalis: benign disorder masquerading as an ovarian malignancy

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    Hyperreactio luteinalis (HL) refers to pregnancy related moderate to marked enlargement of the ovaries due to multiple benign theca lutein cysts. It is caused due to elevated Human chorionic gonadotropins leading to maternal complications such as preeclampsia and preterm delivery may result. We report case of a 24 years old lady, G3P1A1L1 with spontaneous twin pregnancy at 13 weeks + 4 days gestation presented with chief complaint of lower abdominal pain on exertion for 5 days. Ultrasonography (USG) showed a large left ovarian mass in Pouch of Douglas pushing uterus up and extending into the left side of midline upto costal cartilage. It showed multiple thick septations with vascularity pointing towards malignancy. CA-125 was elevated to 193U/ml. Laparotomy was undertaken. Intraoperatively, bilateral huge, congested, bosselated, multicystic ovarian masses were present which replaced normal ovaries and appeared malignant. Bilateral oophorectomy was done. Specimens received for histopathological examination comprised of two large multilobulated, dark brown, ovarian masses with intact glistening capsule. Serial sections through both the masses showed thin walled, multiloculated cysts with smooth inner lining, filled with thin clear to hemorrhagic fluid. On microscopic examination diagnosis of Hyperreactio luteinalis, bilateral ovarian masses were made. HL can be misinterpreted on USG or laparotomy as ovarian malignancy resulting in unnecessary surgical intervention

    Quantitative variations in ovarian follicles of female Sprague Dawley rats after exposure to low dose gamma radiation

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    In the present experiment, an attempt was made to assess the genetic risk of low dose radiations in mammals. For this purpose female Sprague Dawley rats, 11-12 weeks old, were irradiated with whole body Co 60 gamma rays in three fractionated doses of 0.10 Gy (cumulative dose 0.30 Gy) given at an interval of one month at two different dose-rates (0.00368 Gy/min. and 0.0589 Gy/min.). Ovaries were studied for quantitative evaluation of follicles at 1, 4, 12, 28 and 52 weeks after last fractionated exposure. Quantitation revealed lower number of ovarian follicles in irradiated animals than in controls. The follicular number decreased with the advancement of time after last exposure (i.e. 2 months) and reached a peak level on 28 weeks. After that the recovery was evident but the number remained below 25% of total follicles even at 52 weeks autopsy interval, which indicated an irreversible damage in ovarian tissue. Primary follicles were found to be the most radiosensitive among the various types of follicles. The highest loss in these follicles was noted at 12 weeks after exposure with the high dose-rate, where only 10.61% of them were scored. Dose-rate exhibited an inverse relationship with the number of surviving follicles. At the higher dose-rate (0.0589 Gy / min.), depletion in the total follicular number was significantly higher than at the low dose-rate (0.00368 Gy/min.) used

    Single gap s-wave superconductivity in Nb2PdS5

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    Superconducting order parameter and its symmetry are important parameters towards deciphering the pairing mechanism in newly discovered superconducting systems. We report a study on penetration depth measurement on Nb2PdS5 that has recently been reported with extremely high upper critical field with possible triplet pairing mechanism. Our data show that at low temperatures the change in penetration depth is best fitted with BCS s-wave model for single gap. The zero-temperature value of the superconducting energy gap is estimated to be {\Delta}0 = 1.05 meV. The superfluid density in the entire temperature range is well described by single gap for {\lambda} (0) = 220 nm
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