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Energy and spatial momentum of charged rotating frames in tetrad gravity

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Chinese Physics B 2011年第11期20卷 90-101页

作者： gamal g.L.Nashed Mathematics Department Faculty of ScienceAin Shams University

We compute the total energy and the spatial momentum of four charged rotating （Kerr-Newman） frames by using the gravitational energy-momentum 3-form within the framework of the tetrad formulation of the general relativity theory. We show how the effect of the inertial always makes the total energy divergent. We use a natural regularization method, which yields the physical value for the total energy of the system. We show how the regularization method works on a number of different rotating frames that are related to each other by the local Lorentz transformation. We also show that the inertial has no effect on the spatial momentum components.

关键词： teleparallel gravity energy-momentum Weitzenbock connection regularization teleparallelism

Ecological networks and greenways in Europe: reasoning and concepts

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Journal of Environmental Sciences 2003年第2期15卷 173-181页

作者： Rob H.g. Jongman Wageningen UR Expertise Group on Environmental Sciences

The paper gives an overview of approaches towards ecological networks throughout Europe. It does not intend to present a complete picture, but to highlight common developments within countries and regions and show common principles and differences between countries and regions that have to be taken into account when developing a joint European initiative. Countries or regions that have not been included can be active in the same way, but information was not accessible to the authors for different reasons. This overview shows the comparable trends in decline of landscapes and the diversity in approaches to biodiversity conservation and nature conservation planning. Understanding the differences and common issues are of utmost importance to generalise common principles and to understand the way neighbours and other European partners approach problems.

关键词： ecological networks greenways biodiversity land use change homogenisation fragmentation

Micellar sensitized catalytic kinetic spectrophotometry for highly accurate and reproducible determination of Ⅴ(Ⅳ) and Ⅴ(Ⅴ)

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Rare Metals 2014年第4期33卷 466-478页

作者： Ramazan grkan Can Emektas Department of Chemistry Faculty of SciencesUniversity of Cumhuriyet

A highly accurate and reproducible micellar sensitized kinetic method was proposed for determination of V（VI）. The method is based on its catalytic effect on the oxidation of Coomassie brilliant blue R 250 （CBB＋） by bromate at pH 2.0. The reaction was monitored spectro- photometrically by measuring absorbance change with a fixed-time method of 5 min at 594 and 552 nm with and without surfactant. The variables influencing the calibra- tion sensitivity were extensively investigated, and the optimal conditions were established. The linear calibration range was 10-1,600 μg.L-1 with a relative SD ranging from 0.35 % to 3.35 % （for five replicate measurements of 75, 500, 1,000, and 1,500 μg.L-1） and a detection limit of 3.8 μg.L-1. The selectivity was also investigated, and greatly enhanced by suitable masking agents. The method was successfully applied to the analysis of V（IV） in pre- sence of excess V（V） up to 25 fold in environmental waters with the recoveries of 100.0 %-102.8 % for V（IV） and 95.7 %-99.7 % for total V. Its accuracy was validated by analysis of certified reference material via the present kinetic method and standard flame atomic absorption spectrometric method after extractive preconcentration with good agreement between certified and found values.

关键词： Vanadium speciation Kineticspectrophotometry Bromate Coomassie brilliant blue R250 Micellar effect

Nonlinear electrodynamics coupled to teleparallel theory of gravity

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Chinese Physics B 2011年第2期20卷 73-82页

作者： gamal g.L.Nashed Mathematics Department Faculty of ScienceAin Shams UniversityCairoEgypt

Using nonlinear electrodynamics coupled to teleparallel theory of gravity, regular charged spherically symmetric solutions are obtained. The nonlinear theory is reduced to the Maxwell one in the weak limit and the solutions correspond to charged spacetimes. One of the obtained solutions contains an arbitrary function which we call general solution since we can generate from it the other solutions. The metric associated with these spacetimes is the same, i.e., regular charged static spherically symmetric black hole. In calculating the energy content of the general solution using the gravitational energy momentum within the framework of the teleparallel geometry, we find that the resulting form depends on the arbitrary function. Using the regularized expression of the gravitational energy-momentum we obtain the value of energy.

关键词： tetrad theory of gravitation nonlinear electrodynamics spherically symmetric black holes gravitational energy-momentum

Teleparallel equivalent theory of (1+1)-dimensional gravity

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Chinese Physics B 2010年第11期19卷 124-131页

作者： gamal g.L.Nashed Mathematics Department Faculty of ScienceAin Shams UniversityCairoEgypt Centre for Theoretical Physics The Bvitish University in EgyptEl-Sherouk CityMisr-Ismalia Desert RoadPostal No.11837P.O.Box 43Egypt

A theory of （1＋1）-dimensional gravity is constructed on the basis of the teleparallel equivalent of general relativity. The fundamental field variables are the tetrad fields ei^μ and the gravity is attributed to the torsion. A dilatonic spherically symmetric exact solution of the gravitational field equations characterized by two parameters M and Q is derived. The energy associated with this solution is calculated using the two-dimensional gravitational energy- momentum formula.

关键词： teleparallel equivalent theory of (1+1)-dimensional gravity two-dimensional spherically symmetric dilatonic black hole energy

Neuroimaging in atypical normal tension glaucoma:debating routine implementation in the absence of classic neurological findings

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International Journal of Ophthalmology(English edition) 2024年第3期17卷 509-517页

作者： Umay güvenç gülizar Demirok güner Üney Selma Uzman Ophthalmology Department Ankara Training and Research HospitalAnkara 06230Turkey

●AIM:To assess the necessity of neuroimaging in patients with neurological or atypical findings of normal tension glaucoma(NTg)who do not exhibit typical glaucoma manifestations.●METHODS:A retrospective analysis was conducted on 90 atypical NTg patients who underwent cranial magnetic resonance imaging(MRI)due to atypical *** demographic characteristics,clinical parameters,and radiological findings were recorded.●RESULTS:Among the patients,66.7%had abnormal radiology results,with the most common findings being gliosis(34.4%),sequelae of cerebrovascular events and vascular malformations(14.4%),and benign intracranial mass lesions(11%).Non-glaucomatous visual field defects were more frequently observed in patients with abnormal neuroimaging ***,there were no significant differences in intraocular pressure,optic disc parameters,retinal nerve fiber layer thickness,and visual field indices between patients with normal and abnormal radiological *** mean age of the patients was ***,there was a significant age difference,with the abnormal radiology group having a higher median age(P=0.021).●CONCLUSION:The study highlights the importance of cranial imaging in older NTg patients to detect underlying pathologies and prevent *** suggests that neuroimaging may be warranted in NTg patients with atypical visual field defects incompatible with ***,routine neuroimaging in all NTg patients without classic neurological signs may not be necessary.

关键词： normal tension glaucoma neuroimaging atypical visual field defects

Beneficiation of the gold bearing ore by gravity and flotation

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International Journal of Minerals,Metallurgy and Materials 2012年第2期19卷 106-110页

作者： Alim gül Olga Kangal Ayhan A. Sirkeci güven nal Mineral Processing Engineering Department Istanbul Faculty of Mines Technical University Istanbul 34469 Turkey

gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content of the ore. Recently, the recovery of gold using gravity methods has gained attention because of low cost and environmentally friendly operations. In this study, gold pre-concentrates were produced by the stepwise gravity separation and flotation techniques. The Knelson concentrator and conventional flotation were employed for the recovery of gold. gold bearing ore samples were taken from gümüshane Region, northern east part of Turkey. As a result of stepwise Knelson concentration experiments, a gold concentrate assaying around 620 g/t is produced with 41.4wt% recovery. On the other hand, a gold concentrate about 82 g/t is obtained with 89.9wt% recovery from a gold ore assaying 6 g/t Au by direct flotation.

关键词： gold ore treatment beneficiation gold gravity separation flotation

Water sorption thermodynamics in glassy polymers endowed with hydrogen bonding interactions

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Science China(Physics,Mechanics & Astronomy) 2020年第4期63卷 136-154页

作者： g.Scherillo P.La Manna P.Musto g.M ensitieri Department of Chemical Materials and Production EngineeringUniversity of Naples Federico Ⅱnaples 80125Italy Institute for Polymers Composites and BiomaterialsNational Research Council of Italypozzuoli(na)80078Italy

In this contribution, we review and critically compare the results of the analyses we have previously performed on water sorption thermodynamics in a series of polyimides. The experimental investigation was performed by combining gravimetric tests and in situ vibrational spectroscopy. A non-equilibrium theory, based on a compressible lattice framework accounting for the glassy state of the polymer and for the occurrence of hydrogen bonding interactions, has been used to interpret data. Information at a molecular level gained by vibrational spectroscopy has been used to tailor the model equations. The main features of water sorption thermodynamics are well captured, qualitatively and quantitatively, by the adopted model which displays a remarkable agreement with experimental results.

关键词： water polyimides sorption thermodynamics

Synthesis of mesostructured thin films by ionic wind assisted electrostatic spray deposition

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Particuology 2016年第4期14卷 128-132页

作者： S. Khodadadi g.M.H. Meesters g. Biskos Faculty of Applied Sciences Delft University of Technology Delft 2628-BL Netherlands Faculty of Civil Engineering and geosciences Delft University of Technology Delft 2628-CN Netherlands Energy Environment and Water Research Center The Cyprus Institute Hicosia 2121 Cyprus

Thin films produced by electrostatic spray deposition （ESD） have nanometer-sized structures despite the initial sprayed droplets being typically a few tens of microns in diameter. The size and morphology of the resulting structures is not only affected by the solvent properties and drying kinetics, hut also by Coulomb fission owing to the high surface charge density that the droplets build up upon evaporation. In this work we modulate the charge density of the droplets by inducing ionic wind along the spray, and produce mesoscopic structures. Using WO3 as an example, we show that the technique provides a practical way to control the morphology of thin films produced by ESD.

关键词： Electrohydrodynamic atomization Electrospray Aerosol Tungsten oxide Porous thin film