662 research outputs found
Vacuum effects in an asymptotically uniformly accelerated frame with a constant magnetic field
In the present article we solve the Dirac-Pauli and Klein Gordon equations in
an asymptotically uniformly accelerated frame when a constant magnetic field is
present. We compute, via the Bogoliubov coefficients, the density of scalar and
spin 1/2 particles created. We discuss the role played by the magnetic field
and the thermal character of the spectrum.Comment: 17 pages. RevTe
Influence of waste glass in the foaming process of open cell porous ceramic as filtration media for industrial wastewater
This paper reports the development and testing results of a prototype ceramic filter with excellent sorption properties (<99% elimination in 5 min) leading to good efficacy in the removal of industrial contaminants (Reactive Bezaktiv Turquoise Blue V-G (BTB) dye). The novelty in the investigation lies in developing the filter material obtained from the recycling of waste glass combined with highly porous open-cell clay material. This newly developed material showed a significant reduction in the energy requirements (sintering temperature required for the production of industrial filters) thus addressing the grand challenge of sustainable and cleaner manufacturing. The methodology entails sintering of the clay foam (CF) at temperatures ranging from 800 to 1050 °C and blending it with 5%, 7% and 10 wt% milled glass cullet. One of the aims of this investigation was to evaluate and analyse the effect of the pH of the solution, contact time and equilibrium isotherm on the sorption process and the mechanical compressive strength, porosity, water uptake. From the kinetic studies, it was discovered that the experimental results were well aligned with the pseudo-second-order model and chemisorption was discovered to be a mechanism driving the adsorption process. These findings are crucial in designing cost-effective industrial filtration system since the filter material being proposed in this work is reusable, recyclable and readily available in abundance. Overall, the pathway for the reuse of waste glass shown by this work help address the sustainability targets set by the UN Charter via SDG 6 and SDG 12
Field induced evolution of regular and random 2D domain structures and shape of isolated domains in LiNbO<sub>3</sub> and LiTaO<sub>3</sub>
The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging
Induced magnetic anisotropy features in FeCrSiBNbCu nanocrystalline alloy: Role of stress distribution proven by direct X-ray measurements
Fe73.5-xCrxSi13.5B9Nb 3Cu1 (x = 1, 2, and 3) amorphous ribbons were prepared by single roller rapid quenching technique. Both conventional and stress annealing at 520 C for 2 h at the value of the specific load of 150 MPa resulted in the formation of a nanocrystalline structure with average grain size about 13 nm. No significant differences in crystallite size were observed for all samples under consideration. The crystallite orientations were practically isotropic indicating no texture in the samples of all types. For all conventionally annealed ribbons a longitudinal effective magnetic anisotropy with an easy magnetization axis parallel to the ribbon axis was observed. For all stress annealed ribbons a transverse induced magnetic anisotropy with the anisotropy constant value of about 1800 ± 50 J/m3 was evident. Induced magnetic anisotropy features in FeCrSiBNbCu nanocrystalline alloy, namely an importance of the stress distribution was proven by direct X-ray measurements. A very good correlation between the induced magnetic anisotropy constant values and anisotropic stress distribution was observed. © 2013 Elsevier B.V. All rights reserved
Equivalence of the Path Integral for Fermions in Cartesian and Spherical Coordinates
The path-integral calculation for the free energy of a spin-1/2 Dirac-fermion
gas is performed in spherical polar coordinates for a flat spacetime geometry.
Its equivalence with the Cartesian-coordinate representation is explicitly
established. This evaluation involves a relevant limiting case of the fermionic
path integral in a Schwarzschild background, whose near-horizon limit has been
shown to be related to black hole thermodynamics.Comment: 16 page
The Angular Momentum Operator in the Dirac Equation
The Dirac equation in spherically symmetric fields is separated in two
different tetrad frames. One is the standard cartesian (fixed) frame and the
second one is the diagonal (rotating) frame. After separating variables in the
Dirac equation in spherical coordinates, and solving the corresponding
eingenvalues equations associated with the angular operators, we obtain that
the spinor solution in the rotating frame can be expressed in terms of Jacobi
polynomials, and it is related to the standard spherical harmonics, which are
the basis solution of the angular momentum in the Cartesian tetrad, by a
similarity transformation.Comment: 13 pages,CPT-94/P.3027,late
ХИМИОЛУЧЕВОЙ КОМПОНЕНТ КОМБИНИРОВАННОГО ЛЕЧЕНИЯ РАКА ОРОФАРИНГЕАЛЬНОЙ ОБЛАСТИ
Treatment of malignant oropharyngeal tumors - one of the most difficult problems of modern oncology. This is caused by the intensive growth of incidence, a large proportion of advanced cancers at the time of primary visit to a doctor and low 5-year survival. The aim of this study is to improve the efficiency of treatment of patients with oropharyngeal cancer by implementation of the use of self- or neoadjuvant chemoradiotherapy.Лечение злокачественных орофарингеальных опухолей — одна из сложнейших проблем современной онкологии. Это обусловлено интенсивным ростом заболеваемости, большим удельным весом поздних стадий рака при первичном обращении, низкими показателями 5‑летней выживаемости. Цель исследования — повышение эффективности лечения больных орофарингеальным раком путем использования самостоятельной или неоадьювантной химиолучевой терапии
Charges and fields in a current-carrying wire
Charges and fields in a straight, infinite, cylindrical wire carrying a
steady current are determined in the rest frames of ions and electrons,
starting from the standard assumption that the net charge per unit length is
zero in the lattice frame and taking into account a self-induced pinch effect.
The analysis presented illustrates the mutual consistency of classical
electromagnetism and Special Relativity. Some consequences of the assumption
that the net charge per unit length is zero in the electrons frame are also
briefly discussed
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