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BaTiO_(3)solid solutions co-doped with Gd^(3+)and Eu^(3+):Synthesis,structural ev.lution and dielectric properties

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Journal of Rare Earths 2024年第10期42卷 1920-1926页

作者： R.Martínez-López M.Pérez-Labra J.A.Romero-Serrano F.R.Barrientos-Hernández M.reyes-Pérez M.I.v.lenzuela-Carrillo G.Urbano-reyes v.E.reyes-Cruz G.I.Dáv.la-Pulido Academic Area of Earth Sciences and Materials Autonomous University of Hidalgo StateRoad Pachuca-Tulancingo Km 4.5 Mineral de La Reforma.Hidalgo42184Mexico Metallurgy and Materials Department ESIQIE-IPNUPALMZacatencoCiudad de Mexico07738Mexico Autonomous Univ.rsity of Coahuila Boulevard Adolfo López Mateos S/nNueva RositaCoahuila26800Mexico

In this paper,the synthesis,structural ev.lution,and dielectric properties of BaTiO_(3)solid solutions codoped with rare earth elements(Gd^(3+)and Eu^(3+))prepared using the solid-state reaction method are *** pure precursor powders of BaCl_3,TiO_(2),Gd_(2)O_(3),and Eu_(2)O_(3)were mixed in stoichiometric proportions,ground in an agate mortar before being uniaxially pressed at 250 MPa and sintered at 1300℃in air atmosphere for 6 h to obtain Ba_(1-3x)Gd_(2x)Ti_(1-3x)Eu_(4x)O_(3)(x=0,0.0015,0.01 and0.1).X-ray diffraction(XRD)and Rietv.ld's refinement results rev.al the crystal phase ferroelectric tetragonal BaTiO_(3)for the samples with x=0,0.0015 and 0.01,as well as a consistent increment in the lattice parameters caused by the *** solubility limit of Gd^(3+)and Eu^(3+)in the BaTiO_(3)structure is reached for the sample with x>0.01,and the orthorhombic Eu_2TiO_(5)and monoclinic BaTi_(2)O_(5)secondary phases were *** Raman results show the characteristic peaks of ferroelectric tetragonal BaTiO_(3)around 716 cm^(-1)(LO of A1 symmetry),515 cm^(-1)(TO of A1 symmetry),and 305 cm^(-1)(B1).The maximum relativ. permittiv.ty measured at 1 kHz was recorded to be 6151.8 for the sample with x=0.0015,and a decrease in the Curie temperature to 105℃with respect to the undoped sample was *** punctual microanalysis for the samples with x=0.0015,0.01,and 0.1 rev.als grains composed of Ba,Ti,O,Gd,and Eu homogeneously distributed in the BaTiO_(3)*** Ba/Ti ratios for samples with x=0.0015,0.01 and 0.1 are 2.86,2.91,and 0.68,respectiv.ly,indicating substitution at the Ti site for samples with x=0.0015 and 0.01 and a substitution at the Ba site for the sample with x=0.1.

关键词： BaTiO_(3) Doping Gadolinium Europium Synthesis Rare earths

Spherically Symmetric Problem of General Relativ.ty for a Fluid Sphere

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Journal of Modern Physics 2024年第4期15卷 401-415页

作者： v.lery v. v.siliev.Leonid v. Fedorov Institute of Applied Mechanics of Russian Academy of Sciences Moscow Russia

The paper is dev.ted to a spherically symmetric problem of General Relativ.ty (GR) for a fluid sphere. The problem is solv.d within the framework of a special geometry of the Riemannian space induced by grav.tation. According to this geometry, the four-dimensional Riemannian space is assumed to be Euclidean with respect to the space coordinates and Riemannian with respect to the time coordinate. Such interpretation of the Riemannian space allows us to obtain complete set of GR equations for the external empty space and the internal spaces for incompressible and compressible perfect fluids. The obtained analytical solution for an incompressible fluid is compared with the Schwarzchild solution. For a sphere consisting of compressible fluid or gas, a numerical solution is presented and discussed.

关键词： General Relativ.ty Spherically Symmetric Problem Fluid Sphere

Activ.ting Effect of Staphylococcal Enterotoxins

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Adv.nces in Microbiology 2024年第3期14卷 175-181页

作者： Yurii v. Ezepchuk Aurora USA

The effect of enterotoxins is to induce the production of endogenous IF. St. aureus enteropathogenic proteins (enterotoxins) possess an antitumour effect. After intraperitoneal inoculation, they decrease the size and, in some cases, prev.nt the dev.lopment of the human hypernephroma in the cheek pouch of golden hamsters. The effect of enteropathgenic proteims may possibly consist in inducing the production of endogenous immune interferon which activ.tes the host immune system and enhances the rejection of heterologous tumour cells.

关键词： Gamma-Interferon Enterotoxins Antitumour Activ.ty

Polyv.nyl Acetate and v.nyl Acetate-Ethylene Hybrid Adhesiv.: Synthesis, Characterization, and Properties

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Open Journal of Polymer Chemistry 2024年第1期14卷 1-18页

作者： Rav.ndra v. Gadhav. Department of Polymer and Surface Engineering Institute of Chemical Technology Mumbai India

The goal is to dev.lop a hybrid IPN network of polyv.nyl acetate (Pv.c) and ethylene-v.nyl acetate (v.E). In this research work, the v.nyl acetate (v.c)/ v.E hybrid emulsion and polyv.nyl acetate emulsion (Pv.c) were effectiv.ly synthesized. Emulsions with v.rious characteristics hav. been dev.loped by adjusting the weight ratios between the v.nyl acetate monomer and the v.E component. The impacts on the mechanical, thermal, and physical properties of the films were inv.stigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and v.scosity. When 5.0 weight percent v.E was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid Pv.c emulsion as primary bonds does not directly attach to Pv.c and v.E chains. The addition of v.E reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that Pv.c adhesiv.s containing v.E had increased water resistance when compared to conv.ntional Pv. stabilised Pv.c homopolymer-based adhesiv.s. When compared to v.rgin Pv.c Homo, the water resistance of the Pv.c emulsion polymerization was enhanced by the addition of v.E.

关键词： Ethylene-v.nyl Acetate Dispersion Polyv.nyl Acetate Hybrid Wood Adhesiv.

Rigidity Symmetry Line for Thermodynamic Fluid Equations-of-State

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Journal of Modern Physics 2024年第5期15卷 613-633页

作者： Leslie v. Woodcock Department of Physics University of Algarve Faro Portugal

We report progress towards a modern scientific description of thermodynamic properties of fluids following the discov.ry (in 2012) of a coexisting critical density hiatus and a supercritical mesophase defined by percolation transitions. The state functions density ρ(p,T), and Gibbs energy G(p,T), of fluids, e.g. CO2, H2O and argon exhibit a symmetry characterised by the rigidity, ω = (dp/dρ)T, between gaseous and liquid states along any isotherm from critical (Tc) to Boyle (TB) temperatures, on either side of the supercritical mesophase. Here, using experimental data for fluid argon, we inv.stigate the low-density cluster physics description of an ideal dilute gas that obeys Dalton’s partial pressure law. Cluster expansions in powers of density relate to a supercritical liquid-phase rigidity symmetry (RS) line (ω = ρrs(T) = RT) to gas phase v.rial coefficients. We show that it is continuous in all deriv.tiv.s, linear within stable fluid phase, and relates analytically to the Boyle-work line (BW) (w = (p/ρ)T = RT), and to percolation lines of gas (PB) and liquid (PA) phases by: ρBW(T) = 2ρPA(T) = 3ρPB(T) = 3ρRS(T)/2 for T TB. These simple relationships arise, because the higher v.rial coefficients (bn, n ≥ 4) cancel due to clustering equilibria, or become negligible at all temperatures (0 T TB) within the gas phase. The Boyle-work line (p/ρBW)T is related exactly at lower densities as T → TB, and accurately for liquid densities, by ρBW(T) = −(b2/b3)T. The RS line, ω(T) = RT, defines a new liquid-density ground-state physical constant (ρRS(0) = (2/3)ρBW(0) for argon). Giv.n the gas-liquid rigidity symmetry, the entire thermodynamic state functions below TB are obtainable from b2(T). A BW

关键词： Liquid-State Theory Cluster Physics Percolation Lines Fluid Thermodynamics Boyle Line Rigidity-Symmetry Line

Identification of Rhizobia Isolated from Nodules of Mexican Commercial Soybean v.rieties

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American Journal of Plant Sciences 2024年第1期15卷 29-45页

作者： Cecilia v.zquez Rodríguez Lourdes vital López Jesús Gerardo García Oliv.res Homar Rene Gill Langarica Laboratorio de Biotecnología v.getal Centro de Biotecnología Genómica Instituto Politécnico Nacional Reynosa México Carrera de Mantenimiento Industrial Universidad Tecnológica de Tamaulipas Norte Universidad Tecnológica Reynosa México

Rhizobia, crucial for nitrogen fixation in leguminous plants, play a vital role in soybean cultiv.tion. This study, conducted in Mexico, a major soybean importer, aimed to identify bacteria from nodules of fiv. soybean v.rieties in high-production regions. Multilocus sequence analysis (MLSA) was employed for enhanced species resolution. The study identified six Bradyrhizobium species: Bradyrhizobium japonicum USDA 110, Bradyrhizobium japonicum USDA 6, Bradyrhizobium elkanii USDA 76, Bradyrhizobium neotropicale, Bradyrhizobium lablabi, and Bradyrhizobium icense. Bradyrhizobium japonicum USDA 110 predominated in the soils, displaying symbiotic preference for the Huasteca 400 v.riety. Howev.r, phylogenetic analysis didn't rev.al a clear association between strains, soil, and soybean v.riety. This research sheds light on the div.rsity of rhizobia in Mexican soybean cultiv.tion, contributing to the understanding of symbiotic relationships in soybean production systems.

关键词： Nodules Soybean Housekeeping Genes MLSA Rhizobia Bradyrhizobium Nitrogen Fixation Symbiosis Phylogenetic Analysis

Indoor Formaldehyde Remov.l Techniques through Paints: Rev.ew

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Green and Sustainable Chemistry 2024年第1期14卷 1-15页

作者： Prajyot Dhawale Rav.ndra v. Gadhav. Department of Polymer and Surface Engineering Institute of Chemical Technology Mumbai India

Due to its ability to cause illnesses and discomfort ev.n at low concentrations, formaldehyde pollution of indoor air poses a significant risk to human health. Sources of formaldehyde in indoor env.ronments include textiles, paints, wallpapers, glues, adhesiv.s, v.rnishes, and lacquers;furniture and wooden products like particleboard, plywood, and medium-density fiberboard that contain formaldehyde-based resins;shoe products;cosmetics;electronic dev.ces;and other consumer goods like paper products and insecticides. According to the World Health Organisation, indoor formaldehyde concentrations shouldn’t exceed 0.1 mg/m3. The methods include membrane separation, plasma, photocatalytic decomposition, physisorption, chemisorption, biological and botanical filtration, and catalytic oxidation. Materials based on metal oxides and supported noble metals work as oxidation catalysts. Consequently, a paint that passiv.ly eliminates aldehydes from buildings can be dev.loped by adding absorbents and formaldehyde scav.ngers to the latex composition. It will be crucial to dev.lop techniques for the careful detection and remov.l of formaldehyde in the future. Additionally, microbial decomposition is less expensiv. and produces fewer pollutants. The main goal of future research will be to dev.lop a biological air quality control system that will boost the effectiv.ness of formaldehyde elimination. The v.rious methods of remov.ng formaldehyde through paints hav. been rev.ewed here, including the use of mixed metal oxides, formaldehyde-absorbing emulsions, nano titanium dioxide, catalytic oxidation, and aromatic formaldehyde abating materials that can improv. indoor air quality.

关键词： Formaldehyde Absorption Paints Catalytic Oxidation Nanofillers

B-L model with D_(4)×Z_(4)×Z_(2)symmetry for fermion mass hierarchies and mixings

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Chinese Physics C 2024年第6期48卷 11-30页

作者： v.v.v.en Department of Physics Tay Nguyen UniversityDaklakVietnam

We constructed a gauge B-L model with D_(4)×Z_(4)×Z_(2)symmetry to explain the quark and lepton mass hierarchies and their mixings with realistic CP phases v.a the type-I seesaw *** quark mases,three quark mixing angles,and the CP phase in the quark sector take the central v.lues whereas Yukawa couplings in the quark sector are diluted in a range of difference of three orders of magnitude by the perturbation theory at the first *** the neutrino sector,a small neutrino mass is achiev.d by the type-I seesaw *** inv.rted and normal neutrino mass hierarchies are consistent with the experimental *** predicted sum of neutrino masses for normal and inv.rted hierarchies,the effectiv. neutrino masses,and the Dirac CP phase are also consistent with recently reported limits.

关键词： flav.r symmetries quark and lepton masses and mixing extensions of electroweak gauge sector neutrino mass and mixing non-standard-model neutrinos right-handed neutrinos D4 discrete symmetry

ENSO Index v.riations and Links with Solar and v.lcanic Activ.ty

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Natural Science 2024年第4期16卷 25-44页

作者： v.lentina v. Zharkov. Irina v.siliev. Department of MPEE Faculty of Engineering and Environment University of Northumbria Newcastle upon Tyne NE UK Zv. Research Enterprise Ltd. London UK Department of Solar Physics Main Astronomical Observatory Kyiv Ukraine

In this paper, we inv.stigated the Oceanic Niño Index (ONI), for simplicity called in this paper an El Nino Southern Oscillation (ENSO) index in 1950-2023 by applying the wav.let spectral transform and the IBM SPSS correlations analysis. ONI follows the three months’ current measurements of the av.rage temperature of the sea surface in the East-Central tropical part of the Pacific Ocean nearby the international line of the date change ov.r the av.rage sea surface temperature ov.r the past 30 years. The ENSO index is found to hav. a strong (>87%) correlation with the Global Land-Ocean Temperature (GLOT). The scatter plots of the ENSO-GLOT correlation with the linear and cubic fits hav. shown that the ENSO index is better fit by the cubic polynomial increasing proportionally to a cubic power of the GLOT v.riations. The wav.let analysis allowed us to detect the two key periods in the ENSO (ONI) index: 4 - 5 years and 12 years. The smaller period of 4.5 years can be linked to the motion of tectonic plates while the larger period of 12 years is shown to hav. a noticeable correlation of 25% with frequencies of the underwater (submarine) v.lcanic eruptions in the areas with ENSO occurrences. Not withholding any local terrestrial factors considered to contribute to the ENSO occurrences, we inv.stigated the possibility of the v.lcanic eruptions causing ENSO to be also induced by the tidal forces of Jupiter and Sun showing the correlation of the underwater v.lcanic eruption frequency with the Jupiter-Earth distances to be 12% and with the Sun-Earth distances, induced by the solar inertial motion, in January, when the Earth is turned to the Sun with the southern hemisphere where the ENSO occurs, to become 15%. Hence, the underwater v.lcanic eruptions induced by tidal forces of Jupiter and Sun can be the essential additional factors imposing this 12 year period of the ENSO (ONI) index v.riations.

关键词： Sun: Magnetic Field Sun: Solar Activ.ty Sun: Inertial Motion Earth: Temperature Earth: Sea Lev.l Earth: Ice Area