2,144 research outputs found

    A Comprehensive Review of The Impact of Quench Nozzles on Pressure Vessel Design

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    This research examines the influence of cooling spout positioning on pressure container blueprints, particularly emphasizing strain features. Sprayers are crucial for ingress and egress objectives in force containers, and although maximum positioning upholds container uniformity, operation necessities occasionally necessitate circumferential positioning, resulting in uniformity disturbance. The Finite Element Method (FEM) is employed to examine the distribution of strain, while pressure container prototypes fluctuate in the number of spouts and inclinations. By means of an all-inclusive examination, it was discovered that the strain measurements for every circumstance were under the security limit of 50 megapascals. Remarkably, the arrangement with four spouts at 90-degree intervals displayed negligible distortion and sustained strain levels within satisfactory boundaries, imparting valuable perceptions for enhancing the pressure container blueprint with cooling spouts on the circumference, guaranteeing structural soundness and security

    Theory of a Higher Order Phase Transition: Superconducting Transition in BKBO

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    We describe here the properties expected of a higher (with emphasis on the order fourth) order phase transition. The order is identified in the sense first noted by Ehrenfest, namely in terms of the temperature dependence of the ordered state free energy near the phase boundary. We have derived an equation for the phase boundary in terms of the discontinuities in thermodynamic observables, developed a Ginzburg-Landau free energy and studied the thermodynamic and magnetic properties. We also discuss the current status of experiments on Ba0.6K0.4BiO3Ba_{0.6}K_{0.4}BiO_3 and other BiO3BiO_3 based superconductors, the expectations for parameters and examine alternative explanations of the experimental results.Comment: 18 pages, no figure

    Dark Energy Content of Nonlinear Electromagnetism

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    Quasi-constant external fields in nonlinear electromagnetism generate a contribution to the energy-momentum tensor with the form of dark energy. To provide a thorough understanding of the origin and strength of the effects, we undertake a complete theoretical and numerical study of the energy-momentum tensor TμνT^{\mu\nu} for nonlinear electromagnetism. The Euler-Heisenberg nonlinearity due to quantum fluctuations of spinor and scalar matter fields is considered and contrasted with the properties of classical nonlinear Born-Infeld electromagnetism. We also address modifications of charged particle kinematics by strong background fields.Comment: 16 pages, 12 figures; reorganized introduction and sections 4 and 5, added further numerical results and discussion, updated references, fixed typo

    Origin of Intrinsic Josephson Coupling in the Cuprates and Its Relation to Order Parameter Symmetry: An Incoherent Hopping Model

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    Experiments on the cuprate superconductors demonstrate that these materials may be viewed as a stack of Josephson junctions along the c-direction. In this paper, we present a model which describes this intrinsic Josephson coupling in terms of incoherent quasiparticle hopping along the c-axis arising from wave-function overlap, impurity-assisted hopping, and boson-assisted hopping. We use this model to compute the magnitude and temperature T dependence of the resulting Josephson critical current j_c (T) for s- and d-wave superconductors. Contrary to other approaches, d-wave pairing in this model is compatible with an intrinsic Josephson effect at all hole concentrations and leads to j_c (T) \propto T at low T. By parameterizing our theory with c-axis resistivity data from YBCO, we estimate j_c (T) for optimally doped and underdoped members of this family. Our estimates suggest that further experiments on this compound would be of great help in elucidating the validity of our model in general and the pairing symmetry in particular. We also discuss the implications of our model for LSCO and BSCCO.Comment: 28 pages, REVTEX, 5 compressed PostScript figures. Substantially expanded and revised from the earlier version. To appear in Physica

    Irradiation Effects on Microstructure and Dielectric Properties of Ba[(Mg0.32Co0.02)Nb0.66]O3 [BMCN] Thin Films

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    Ba[(Mg0.32Co0.02)Nb0.66]O3 [BMCN] thin films prepared on Pt-Si, MgO, Silicon and ITO coated glass substrates by Pulsed Laser Deposition Technique are investigated. Relative growth parameters suggest that ITO coated glass substrate has good potential for growing films with near Nano size columnar grains. In comparison to bulk, dielectric constant and dielectric loss increases in BMCN films. This undesirable rise in dielectric loss can be drastically reduced by a factor of more than 1/100th times through Ag15+ ion irradiation at 1 × 1012 ions/cm2 dose. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3025

    Nature of Correlated Motion of Electrons in the Parent Cobaltate Superconductors

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    Recently discovered class of cobaltate superconductors (Na0.3CoO2.nH2O) is a novel realization of interacting quantum electron systems in a triangular network with low-energy degrees of freedom. We employ angle-resolved photoemission spectroscopy to uncover the nature of microscopic electron motion in the parent superconductors for the first time. Results reveal a large hole-like Fermi surface (consistent with Luttinger theorem) generated by the crossing of super-heavy quasiparticles. The measured quasiparticle parameters collectively suggest a two orders of magnitude departure from the conventional Bardeen-Cooper-Schrieffer electron dynamics paradigm and unveils cobaltates as a rather hidden class of relatively high temperature superconductors.Comment: 5 pages, 4 figures, 1 tabl

    Novel Synthesis and High Pressure Behavior of Na0.3CoO2 x 1.3 H2O and Related Phases

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    We have prepared powder samples of NaxCoO2 x yH2O using a new synthesis route. Superconductivity was observed in Na0.3CoO2 x 1.3H2O between 4 and 5K as indicated by the magnetic susceptibility. The bulk compressibilities of Na0.3CoO2 x 1.3H2O, Na0.3CoO2 x 0.6H2O and Na0.3CoO2 were determined using a diamond anvil cell and synchrotron powder diffraction. Chemical changes occurring under pressure when using different pressure transmitting media are discussed and further transport measurements are advocated.Comment: 7 pages, 4 figures, PRrapid submitte

    A Honeycomb Proportional Counter for Photon Multiplicity Measurement in the ALICE Experiment

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    A honeycomb detector consisting of a matrix of 96 closely packed hexagonal cells, each working as a proportional counter with a wire readout, was fabricated and tested at the CERN PS. The cell depth and the radial dimensions of the cell were small, in the range of 5-10 mm. The appropriate cell design was arrived at using GARFIELD simulations. Two geometries are described illustrating the effect of field shaping. The charged particle detection efficiency and the preshower characteristics have been studied using pion and electron beams. Average charged particle detection efficiency was found to be 98%, which is almost uniform within the cell volume and also within the array. The preshower data show that the transverse size of the shower is in close agreement with the results of simulations for a range of energies and converter thicknesses.Comment: To be published in NIM

    Genetic determinants of cellular addiction to DNA polymerase theta

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    Polymerase theta (Pol θ, gene name Polq) is a widely conserved DNA polymerase that mediates a microhomology-mediated, error-prone, double strand break (DSB) repair pathway, referred to as Theta Mediated End Joining (TMEJ). Cells with homologous recombination deficiency are reliant on TMEJ for DSB repair. It is unknown whether deficiencies in other components of the DNA damage response (DDR) also result in Pol θ addiction. Here we use a CRISPR genetic screen to uncover 140 Polq synthetic lethal (PolqSL) genes, the majority of which were previously unknown. Functional analyses indicate that Pol θ/TMEJ addiction is associated with increased levels of replication-associated DSBs, regardless of the initial source of damage. We further demonstrate that approximately 30% of TCGA breast cancers have genetic alterations in PolqSL genes and exhibit genomic scars of Pol θ/TMEJ hyperactivity, thereby substantially expanding the subset of human cancers for which Pol θ inhibition represents a promising therapeutic strategy

    Photo--assisted current and shot noise in the fractional quantum Hall effect

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    The effect of an AC perturbation on the shot noise of a fractional quantum Hall fluid is studied both in the weak and the strong backscattering regimes. It is known that the zero-frequency current is linear in the bias voltage, while the noise derivative exhibits steps as a function of bias. In contrast, at Laughlin fractions, the backscattering current and the backscattering noise both exhibit evenly spaced singularities, which are reminiscent of the tunneling density of states singularities for quasiparticles. The spacing is determined by the quasiparticle charge νe\nu e and the ratio of the DC bias with respect to the drive frequency. Photo--assisted transport can thus be considered as a probe for effective charges at such filling factors, and could be used in the study of more complicated fractions of the Hall effect. A non-perturbative method for studying photo--assisted transport at ν=1/2\nu=1/2 is developed, using a refermionization procedure.Comment: 14 pages, 6 figure
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