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1.
The magnetic properties of an attractive Hubbard chain are considered. Based on the Bethe Ansatz equations of the problem, exact analytic expressions are derived for the magnetization and susceptibility. These formulae can be evaluated after solving certain derivatives of the Bethe Ansatz equations. These derivative equations are also given. We give the magnetization and susceptibility curves for several values of the interaction-strength and bandfilling. We find that the susceptibility at the onset of magnetization (at the critical field) isfinite for all bandfillings, except for the cases of half filled and empty bands, and in the limit of vanishing interaction. We argue that the finiteness of the initial susceptibility is due to the fermion-like behavior of the bound pairs. We also give the gap (what is equal to the critical field) and the initial susceptibility as functions of the interaction-strength and bandfilling for the cases of nearly half filled and almost empty bands as a function of the interaction, and in the weak coupling limit as a function of the bandfilling. To our knowledge, this is the first Bethe Ansatz calculation for the gap in this latter limit. 相似文献
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A higher resolution edge‐based finite volume method for the simulation of the oil–water displacement in heterogeneous and anisotropic porous media using a modified IMPES method
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Rogério Soares da Silva Paulo Roberto Maciel Lyra Ramiro Brito Willmersdorf Darlan Karlo Elisiário de Carvalho 《国际流体数值方法杂志》2016,82(12):953-978
In this article, we present a higher‐order finite volume method with a ‘Modified Implicit Pressure Explicit Saturation’ (MIMPES) formulation to model the 2D incompressible and immiscible two‐phase flow of oil and water in heterogeneous and anisotropic porous media. We used a median‐dual vertex‐centered finite volume method with an edge‐based data structure to discretize both, the elliptic pressure and the hyperbolic saturation equations. In the classical IMPES approach, first, the pressure equation is solved implicitly from an initial saturation distribution; then, the velocity field is computed explicitly from the pressure field, and finally, the saturation equation is solved explicitly. This saturation field is then used to re‐compute the pressure field, and the process follows until the end of the simulation is reached. Because of the explicit solution of the saturation equation, severe time restrictions are imposed on the simulation. In order to circumvent this problem, an edge‐based implementation of the MIMPES method of Hurtado and co‐workers was developed. In the MIMPES approach, the pressure equation is solved, and the velocity field is computed less frequently than the saturation field, using the fact that, usually, the velocity field varies slowly throughout the simulation. The solution of the pressure equation is performed using a modification of Crumpton's two‐step approach, which was designed to handle material discontinuity properly. The saturation equation is solved explicitly using an edge‐based implementation of a modified second‐order monotonic upstream scheme for conservation laws type method. Some examples are presented in order to validate the proposed formulation. Our results match quite well with others found in literature. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
3.
Bala Karlo Brcanov Dejan Gvozdenović Nebojša 《Central European Journal of Operations Research》2017,25(3):525-543
Central European Journal of Operations Research - In this paper we study a problem that arose while planning the delivery of perishable goods, such as newspapers or foodstuff, in urban areas. The... 相似文献
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Forro L Gaal R Berger H Fazekas P Penc K Kezsmarki I Mihaly G 《Physical review letters》2000,84(9):1938-1941
We report on experiments giving evidence for quantum effects of electromagnetic flux in barium alumosilicate glass. In contrast to expectation, below 100 mK the dielectric response becomes sensitive to magnetic fields. The experimental findings include both lifting of the dielectric saturation by weak magnetic fields and oscillations of the dielectric response in the low temperature resonant regime. As the origin of these effects we suggest that the magnetic induction field violates the time reversal invariance leading to a flux periodicity in the energy levels of tunneling systems. At low temperatures, this effect is strongly enhanced by the interaction between tunneling systems and thus becomes measurable. 相似文献
5.
The possibilities of graphic STM image simulation of a clean Si(1 1 1) 7 × 7 surface at atomic level are indicated. The presented procedure takes into account various types of deformation on the surface near the Fermi level in order to classify them and explain their origin. It also gives a clear hint to insert relevant physical phenomena in a suggested analysis. This goal is achieved exploiting the results of DAS (dimmer adatom stacing fault) model by means of standard mathematical programmes. A clean Si(1 1 1) 7 × 7 surface is considered as the representative example, but similar evaluation is possible for another non-metal and metal surfaces. 相似文献
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Physical properties of NdPd2Ge2 and NdAg2Ge2, crystallizing with the tetragonal ThCr2Si2-type crystal structure, were investigated by means of magnetic, calorimetric, electrical transport as well as by neutron diffraction measurements. The specific heat studies and neutron diffraction measurements were performed down to 0.30 K and 0.47 K, respectively. Both compounds exhibit antiferromagnetic ordering below TN equal to 1.5 K for NdPd2Ge2 and 1.8 K for NdAg2Ge2. Neutron diffraction data for the latter germanide indicate antiferromagnetic collinear structure described by the propagation vector k=(0.5, 0, 0.5). The Nd magnetic moments equal to 2.24(5) μB at 0.47 K are aligned along the a-axis and have the +− sequence within the crystal unit cell. For NdPd2Ge2 only very small Bragg peaks of magnetic origin were observed in the neutron diffraction patterns measured below TN, thus hampering determination of the magnetic structure. Both compounds exhibit metallic-like electrical conduction. From the specific heat data the crystal electric field (CEF) levels schemes were determined. Difference between the overall CEF splitting in the two compounds is correlated with their structural parameters. 相似文献
7.
K Benci L Mandić T Suhina M Sedić M Klobučar S Kraljević Pavelić K Pavelić K Wittine M Mintas 《Molecules (Basel, Switzerland)》2012,17(9):11010-11025
We report here on the synthesis and in vitro anti-tumor effects of a series of novel 1,2,4-triazole (compounds 3-6), 4,5-dicyanoimidazole (compound 7), and purine (compounds 8-13) coumarin derivatives and their acyclic nucleoside analogues 14-18. Structures of novel compounds 3-18 were deduced from their 1H- and 13C-NMR and corresponding mass spectra. Results of anti-proliferative assays performed on a panel of selected human tumor cell lines revealed that compound 6 had moderate cytostatic activity against the HeLa cell line (IC50 = 35 μM), whereas compound 10 showed moderate activity against the HeLa (IC50 = 33 μM), HepG2 (IC50 = 25 μM) and SW620 (IC50 = 35 μM) cell lines. These compounds showed no cytotoxic effects on normal (diploid) human fibroblasts. 相似文献
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Karlo Jurica Vesna Benković Sunčana Sikirić Irena Brčić Karačonji Nevenka Kopjar 《Natural product research》2020,34(16):2354-2357
Abstract Although strawberry tree (Arbutus unedo L.) leaves have long been used as a herbal remedy, insufficient information is available on their nephrotoxicity. We assessed the safety of strawberry tree water leaf extract and its key component arbutin, administered per os to Lewis rats of both genders at 200?mg/kg b.w./day for 14 and 28 days. The effects of the tested compounds on DNA integrity in renal cells was evaluated using alkaline comet assay, while kidney function was studied using serum creatinine and urea levels. Strawberry tree water leaf extract showed high biocompatibility with kidney tissue. It did not impair DNA integrity of renal cells and kidney function, either in male or female rats. However, exposure to single arbutin affected the levels of primary DNA damage in renal cells which could be related to metabolic conversion of arbutin into hydroquinone, whose nephrotoxicity has previously been proven. 相似文献
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A. Szytu?a D. Kaczorowski B. Penc A. Hoser 《Journal of magnetism and magnetic materials》2010,322(19):2973-2977
Polycrystalline sample of ErFe2Ge2 was investigated by means of magnetic susceptibility, heat capacity and electrical resistivity measurements, as well as by powder neutron diffraction. All these experiments yielded an evidence of magnetic ordering setting at about 3 K. The low-temperature neutron data revealed the formation of a sine-modulated commensurate antiferromagnetic structure characterized by the propagation vector k=(0, 0, ). The erbium magnetic moment is aligned parallel to the crystallographic a-axis. At T=1.55 K it is equal to 7.06(5) μB. 相似文献