Quantum Resources in Heisenberg XX Model Under Noisy Environment

International Journal of Theoretical Physics - In this paper, we investigate Einstein-Podolsky-Rosen steering, Bell non-locality, first-order coherence and concurrence in the spin- $\frac {1}{2}$...     

Restoration of Coherence by Local PT-Symmetric Operator

In this work, we mainly investigate effect of PT-symmetric operation on the dynamics of the relative entropy of coherence for a two-level system within non-Markovian environments, and put forward a feasible physical scheme to recover coherence by means of optimal PT-symmetric operation. The results show that the damaged quantum coherence can be restored to a large extent. Furthermore, the freezing phenomenon of the coherence can be detected by using the optimal PT-symmetric operation strength within the non-Markovian environments.

     

1—间甲氧苯基—2—二甲胺甲基环己醇的合成与结构研究

通过间溴苯甲醚与２－二甲胺甲基环己酮反应制得１－间甲氧苯基－２－二胺甲基环己醇，对其分离得到相应的顺反异构体，对反应的立体化学进行了分析，并对＾１３Ｃ ＮＭＲ谱确定了顺反异构体的构型。     

Lattice preconditioning for the real relaxation branch-and-bound approach for integer least squares problems

The integer least squares problem is an important problem that arises in numerous applications. We propose a real relaxation-based branch-and-bound (RRBB) method for this problem. First, we define a quantity called the distance to integrality, propose it as a measure of the number of nodes in the RRBB enumeration tree, and provide computational evidence that the size of the RRBB tree is proportional to this distance. Since we cannot know the distance to integrality a priori, we prove that the norm of the Moore–Penrose generalized inverse of the matrix of coefficients is a key factor for bounding this distance, and then we propose a preconditioning method to reduce this norm using lattice reduction techniques. We also propose a set of valid box constraints that help accelerate the RRBB method. Our computational results show that the proposed preconditioning significantly reduces the size of the RRBB enumeration tree, that the preconditioning combined with the proposed set of box constraints can significantly reduce the computational time of RRBB, and that the resulting RRBB method can outperform the Schnorr and Eucher method, a widely used method for solving integer least squares problems, on some types of problem data.     

双盘状ZnO的可控制备

采用水热法制备了形貌可控、 尺寸均一的双盘状ZnO. X射线粉末衍射(XRD)、 扫描电子显微镜(SEM)及透射电子显微镜(TEM)等测试结果表明, 制备的ZnO具有六方纤锌矿结构, 由2个直径约为4 μm, 厚度约为600 nm的圆盘复合而成. 考察了反应温度和乙酸锌与柠檬酸钾的摩尔比对产物形貌与尺寸的影响, 实现了双盘状ZnO的可控合成, 并初步探讨了其形成机理. 荧光光谱显示, 双盘状ZnO的紫外发射峰半高宽约为10 nm, 比块体ZnO的紫外发射峰半高宽(18 nm)窄, 表明双盘状ZnO具有更好的光学特性.     

A pillared metal-organic framework incorporated with 1,2,3-triazole moieties exhibiting remarkable enhancement of CO(2) uptake

The replacement of the pillar ligand, 4,4'-bipyridine, in the prototypal pillared MOF, MOF-508, with the custom-designed ligand, 4,4'-(2H-1,2,3-triazole-2,4-diyl)dipyridine, affords a porous metal-triazolate framework, MTAF-3, which demonstrates remarkable enhancement of CO(2) uptake capacity by a factor of ～3 compared to the parent MOF-508.     

Solubilities of hydrogen and deuterium gases in water and their isotope fractionation factor

Solubilities of deuterium gas in water were measured at 5° intervals from 278 to 303°K with an overall precision of about 0.4%. Thermodynamic functions for the solution process were calculated for deuterium gas and compared with the corresponding quantities for hydrogen gas based on the reported data of Crozier and Yamamoto. Henry's law constantsk, obtained at different temperaturesT, were fitted to an equation of the form $$R ln ({1 \mathord{\left/ {\vphantom {1 k}} \right. \kern-\nulldelimiterspace} k}) = A + {B \mathord{\left/ {\vphantom {B {T + }}} \right. \kern-\nulldelimiterspace} {T + }}C ln T + DT$$ Isotope fractionation factors α for the D₂/H₂ system were obtained with careful error estimates. Compared at the same temperature, D₂ gas is more soluble in water than H₂ gas, showing a “normal” isotope effect, and the value of α decreases from 1.086 (±0.005) at 278°K to 1.065 (±0.006) at 303°K. The large isotope effect may be attributed, at least partly, to the difference in the zero-point energies between H₂ and D₂ molecules when they execute oscillatory motion in a solvent cage.     

Chemical shifts of aqueous nonelectrolyte solutions: Influence of the polar and nonpolar groups on the water proton shifts at 0°C

Hydroxyl-proton chemical shifts of alcohol mixtures and aqueous solutions containing some nonelectrolytes (alcohols, ketones, cyclic ethers, and amines) have been measured at 60 MHz and at 0°C. Methyl-proton resonance of the solutes was used as the internal reference and the water-proton shifts in solutions were measured with respect to pure water. Downfield shifts for some alcohols (particularly tertiary butanol and iso-propanol), cyclic ethers, and amines in the water-rich region were confirmed For alcohols and some other nonelectrolytes in water, the observed shifts were decomposed to component contributions arising from the polar group effect, solute proton effect, and nonpolar group effect. Polar effects are found to contribute a substantial fraction of the observed downfield shifts. After subtracting these polar contributions, however, there still remains certain amounts of downfield shifts which may be attributed to the effect of nonpolar groups on the water structure. The downfield shifts are found to be relatively large when the solutes have branched alkyl groups with nearly spherical shape and with diameters of about 5 Å. Strikingly large downfield shifts of water proton resonance were found for some secondary amines and tertiary diamines with globular shape. However, in view of the extrapolation technique employed in evaluating the polar group effect, the downfield nonpolar group effect we estimated should be considered as the upper limits.Work done at Professor Hertz's laboratory in Karlsruhe on a sabbatical leave from Clark University.     

Post-Synthetic Modification of Porphyrin-Encapsulating Metal-Organic Materials by Cooperative Addition of Inorganic Salts to Enhance CO(2) /CH(4) Selectivity

Keeping MOM: Reaction of biphenyl-3,4',5-tricarboxylate and Cd(NO(3) )(2) in the presence of meso-tetra(N-methyl-4-pyridyl)porphine tetratosylate afforded porph@MOM-11, a microporous metal-organic material (MOM) that encapsulates cationic porphyrins and solvent in alternating open channels. Porph@MOM-11 has cation and anion binding sites that facilitate cooperative addition of inorganic salts (such as M(+) Cl(-) ) in a stoichiometric fashion.     

A nuclear magnetic resonance study of dynamics in toluene-polyisobutylene solutions: 1. Penetrant diffusion and Fujita theory

The self-diffusion coefficients of toluene in polyisobutylene (PIB) solutions were determined using the pulsed field gradient nuclear magnetic resonance technique. The volume fraction of toluene in the polymer was varied from 0.045 up to 0.712 and the temperature was varied from 225 K up to 368 K. The concentration dependence of the data was interpreted using the Fujita free volume theory and the temperature dependence was interpreted with the WLF equation. These models describe separately the concentration and temperature dependencies of the toluene self-diffusion coefficients very well and the resulting free volume parameters are in good agreement with the ones extracted from the analysis of viscosity data on the same system. ©1995 John Wiley & Sons, Inc.