高脂饮食对小鼠脂肪代谢和矿物元素代谢的影响

为探讨高脂饮食对小鼠脂肪代谢和矿物元素代谢的影响,用昆明(KM)小鼠24只,出生28 d后随机分成2组,各12只,分别给予高脂饲料与普通饲料,饲养至第9周眼球取血处死,取皮下、腹腔、肠系膜脂肪,毛,肝,血,计算体质量脂肪质量比,测定毛、肝、血中Zn、Ca、Cu、Mn、Mg、Fe含量。结果表明,高脂饮食小鼠体质量增加(P<0.05),单位腹腔脂肪及血Ch显著性增加(P<0.01)。肝Zn、Cu、Mg、Fe、Mn显著降低(P<0.01),血凝块Zn升高(P<0.05),Cu降低(P<0.05),毛Mg降低(P<0.05)。提示高脂饮食引起体质量与血脂增加,脂肪堆积,矿物元素代谢紊乱;不同器官矿物元素的代谢紊乱有差异,以肝脏最显著。     

Linear expansion of the eigenvalues of a Hermitian matrix and its application to the analysis of the electronic spectra of 3d ions in crystals

It is shown that the eigenvalues E_i of a Hermitian matrix H with matrix elements H_ij = Σ_kA^k_ija_k, where A^k_ij are known numbers and a_k a set of parameters, can be exactly expanded as $\text{E}{}_{\mathrm{i}}\text{= Σ}{}_{\mathrm{k}}\text{(}\text{?E}{}_{\mathrm{i}}\text{?a}{}_{\mathrm{k}}\text{)a}{}_{\mathrm{k}}$. This property is applied to the analysis of the optical spectra of transition metal ions in crystals proposed by L. Pueyo, M. Bermejo, and J. W. Richardson (J. Solid State Chem.31, 217, 1980), and it is shown that this method represents the best fit of the Hamiltonian eigenvalues to the observed (or calculated) spectrum. Further advantages of using this property, in connection with the spectral analysis, are the minimization of the errors associated with the numerical approximations and a reduction in computer time. In the molecular orbital calculation of the optical or uv spectra of these systems, this linear expansion of the eigenvalues give a detailed interpretation of the improvements produced by refined calculations, such as those including configuration interaction. In particular, the changes in one-electron energy and in open-shell repulsion interactions associated with the refinement can be clearly and easily formulated. As examples, the computed spectra of CrF^4?₆ and CrF^3?₆ are discussed.     

The structure, energetics, and nature of the chemical bonding of phenylthiol adsorbed on the Au(111) surface: implications for density-functional calculations of molecular-electronic conduction

The adsorption of phenylthiol on the Au(111) surface is modeled using Perdew and Wang density-functional calculations. Both direct molecular physisorption and dissociative chemisorption via S-H bond cleavage are considered as well as dimerization to form disulfides. For the major observed product, the chemisorbed thiol, an extensive potential-energy surface is produced as a function of both the azimuthal orientation of the adsorbate and the linear translation of the adsorbate through the key fcc, hcp, bridge, and top binding sites. Key structures are characterized, the lowest-energy one being a broad minimum of tilted orientation ranging from the bridge structure halfway towards the fcc one. The vertically oriented threefold binding sites, often assumed to dominate molecular electronics measurements, are identified as transition states at low coverage but become favored in dense monolayers. A similar surface is also produced for chemisorption of phenylthiol on Ag(111); this displays significant qualitative differences, consistent with the qualitatively different observed structures for thiol chemisorption on Ag and Au. Full contours of the minimum potential energy as a function of sulfur translation over the crystal face are described, from which the barrier to diffusion is deduced to be 5.8 kcal mol(-1), indicating that the potential-energy surface has low corrugation. The calculated bond lengths, adsorbate charge and spin density, and the density of electronic states all indicate that, at all sulfur locations, the adsorbate can be regarded as a thiyl species that forms a net single covalent bond to the surface of strength 31 kcal mol(-1). No detectable thiolate character is predicted, however, contrary to experimental results for alkyl thiols that indicate up to 20%-30% thiolate involvement. This effect is attributed to the asymptotic-potential error of all modern density functionals that becomes manifest through a 3-4 eV error in the lineup of the adsorbate and substrate bands. Significant implications are described for density-functional calculations of through-molecule electron transport in molecular electronics.     

ABO_3，A_2BO_4型复合氧化物催化剂用于CO，CH_4，NH_3完全氧

本文探讨了ＣＯ，ＣＨ＿４和ＮＨ＿３在ＬａＮｉＯ＿３，Ｌａ＿２ＮｉＯ＿４和ＬａＳｒＮｉＯ＿４三个催化剂上的氧化行为，并得出结论：对于ＣＯ氧化，关键步骤在于ＣＯ在催化剂表面上的络合活化。Ｎｉ￣（３＋）含量越高，越利于ＣＯ的络合活化。对于氨氧化，催化反应遵循氧化－还原机理。Ｎｉ￣（３＋）是主要的活性离子，晶格氧是主要活性氧种。对于ＣＨ＿４氧化，催化机理较复杂，只是发现Ａ＿２ＢＯ＿４型氧化物（Ｌａ＿２ＮｉＯ＿４，ＬａＳｒＮｉＯ＿４）比ＡＢＯ＿３型氧化物（ＬａＮｉＯ＿３）较利于ＣＨ＿４的氧化。     

Structure and properties of transition-metal compounds. A systematic study of basis set effects in ab initioSCF calculations

The recently developed Gaussian basis functions [2] were used in calculations on the ground electronic states of molecules containing transition-metal atoms: ScF₃, TiCl₄, ZrCl₄, Cr(CO)₆, Ni(CO)₄, CuF, CuCl, Zn(CH₃)₂, and Cd(CH₃)₂. The usefulness of minimal basis sets, the importance of splitting of the valence part of the minimal basis sets, the role of the triple splitting of the d-block functions, and the need for p-, d-, and f-type polarization functions were discussed in the context of the geometrical structure and the firstorder electronic properties of the transition-metal atom compounds.     

Hybrid nanoparticle design based on cationized gelatin and the polyanions dextran sulfate and chondroitin sulfate for ocular gene therapy

We describe the development of hybrid nanoparticles composed of cationized gelatin and the polyanions CS and DS for gene therapy in the ocular surface. The physicochemical properties of the nanoparticles that impact their bioperformance, such as average size and zeta potential, can be conveniently modulated by changing the ratio of polymers and the crosslinker. These systems associate plasmid DNA and are able to protect it from DNase I degradation. We corroborate that the introduction of CS or DS in the formulation decreases the in vitro toxicity of the nanoparticles to human corneal cells without compromising the transfection efficiency. These nanoparticles are potential candidates for the development of safer and more effective nanomedicines for ocular therapy.     

On the thermodynamics of an ideal fermi gas on the lattice at finite density

We study the ideal gas of fermions on a lattice at finite density for both naive and Wilson fermions. Comparing the thermodynamical quantities thus calculated with the known results in the continuum theory, we are led to propose a modification of the naive form of the lattice action, which is same for both the naive and the Wilson fermions. The thermodynamical quantities, calculated by using this form, are shown to have the correct continuum limit.     

A wave-packet formulation of multiparticle production at high energies

Starting from a free boson gas in a box, we formulate a statistical approach to multi-particle production. The specific feature of the small box quantization is the fact that one-particle wave functions are wave packets instead of plane waves. In this context we investigate the jet model with Bose-Einstein (BE) statistics. The transverse cut-off function is naturally related to the size of the box (production region). We compare our results with experimental data.     

Nanoparticle adsorption on a weak polyelectrolyte. Stiffness, pH, charge mobility, and ionic concentration effects investigated by Monte Carlo simulations

Monte Carlo simulations have been used to study two different models for a weak linear polyelectrolyte in the presence of nanoparticles: (i) a rodlike and (ii) a flexible polyelectrolytes. The use of simulated annealing has made it possible to simulate a polyelectrolyte chain in the presence of several nanoparticles by improving conformation sampling and avoiding multiple minima problems when dense conformations are produced. Nanoparticle distributions along the polymer backbone were analyzed versus the ionic concentration, polyelectrolyte stiffness, and nanoparticle surface charge. Titration curves were calculated and the influences of the ionic concentration, solution pH, and number of adsorbed nanoparticles on the acid/base polyelectrolyte properties have been systematically investigated. The subtle balance of attractive and repulsive interactions has been discussed, and some characteristic conformations are presented. The comparison of the two limit models provides a good representation of the stiffness influence on the complex formation. In some conditions, overcharging was obtained and presented with respect to both the polyelectrolyte and nanoparticle as the central element. Finally, the charge mobility influence along the polyelectrolyte backbone was investigated by considering annealed and quenched polyelectrolyte chains.