桩端土和桩侧土在荷载传递过程中的相互强化

通过模型试验和现场测试,对桩侧土和桩端土在荷载传递过程中的相互强化作用进行了研究,并对这种相互强化作用机理进行了深入的理论分析。研究发现:不但桩端土的强度对桩侧土的极限摩阻力的发挥具有强化作用,同样,桩侧土的强度对桩端的极限端阻力的发挥也具有强化作用。

中国周边关系与边疆治理的互动:历史、模式及影响因素

由于独特的地理位置,边疆治理不仅是一个国内问题,而且也是一个与本国和周边国家关系密切相关的问题。从国际政治的角度来看,新中国建立后的边疆治理政策,其主题经历了以国防安全为首要考虑的治理政策到以发展为首要考虑的治理政策的变化。不同时期的边疆治理政策所取得的成效是不一样的。但是,很明显,周边关系的好坏影响甚至决定着边疆治理的成效,而边疆治理的好坏也对周边关系产生正面或负面的影响,两者之间呈现出一种相互强化的关系。同时,与边疆毗邻的周边地区的稳定状况也对边疆治理的成效有着直接的或潜在的影响。从层次分析的角度看,影响周边关系与边疆治理互动关系的因素既有国际体系层面的因素,也有大国的因素,还有国内政治的因素。

住房分配与保障:一个民生议题

计划经济时代的城市住房分配采取反市场的再分配模式,单位间与单位内的等级秩序是住房分配的表征。转型经济时期的住房分配则采取以市场为导向的分配模式,住房市场是一种混合市场,由官僚结构、单位因素、家庭结构及早期房改制度等共同左右。在这种情况下,市场与再分配存在相互强化,结果导致"强市场强制度"的过度保障、"超强制度"的错位保障及"弱制度弱市场"的缺位保障,这些问题应是未来制定住房政策的关注焦点。

Spatio-temporal Analysis of Urban Spatial Interaction in Globalizing China—A Case Study of Beijing-Shanghai Corridor

This paper aims to explore urban geography with a new perspective. Endowed with the urban geography connotations, an improved data field model is employed to integrate temporal dimension into spatial process of cities in a typical region in this article. Taking the Beijing-Shanghai Corridor including 18 cities as an example, the authors chose the city centricity index (CCI) and the spatial data field model to analyze the evolution process and features of sub-region and urban spatial interaction in this corridor based on the data of 1991, 1996 and 2002. Through the analy- sis, we found that: 1) with the improvement of the urbanization level and the development of urban economy, the cit- ies’ CCI grew, the urban spatial radiative potential enhanced and the radiative range expanded gradually, which reflects the urban spatial interaction’s intensity has been increasing greatly; 2) although the spatial interaction intensity among the cities and sub-regions in the Beijing-Shanghai Corridor was growing constantly, the gap of the spatial interaction strength among different cities and sub-regions was widening, and the spatial division between the developed areas and the less developed areas was obvious; and 3) the intensity of the spatial interaction of Beijing, Shanghai and their urban agglomerations was far greater than that in small cities of other parts of the corridor, and it may have a strong drive force on the choice of spatial location of the economic activities.

Automatic Organization, Thinking Motion and Dynamics of the Universe

There are many automatic organization phenomena and automatic organization unities in the universe. The automatic organization whole refers to a life body with the thinking. The thinking is the core of automatic organization. The thinking is at eternal restless motion and binds to substances. The universe, organism and society are the automatic organization unities or life systems with the thinking. The thinking can perceive, attract, drive, organize and control all individuals and it is a force of life structure or universal gravitation and universal repulsion. The thinking has a life structure, a template and dynamic of entity-life＇s automatic organization. Life body has five dynamic systems： the thinking motion and information flow, breathing motion, closed-loop current （particle flow） and energy flow, interaction among state-varying, state-stabilizing and control organizations and active ＆ automatic chemical-physical reactions, cardiac pulsation and active motion and transportation. Human, galaxies and society can change from low to high energy state initiatively. This is realized by controlling the desires of life entity via the thinking and breathing motions and by altering the body＇s binding forces dominating the life entity （in turn, by bond force, strong interaction and quark confinement）. All forces in the universe present in the universe of life： force of the thinking-universal gravitation and universal repulsion, electromagnetic interaction, bond force, strong interaction, quark confinement and weak interaction. Under the automatic organization of the thinking, these forces bind into a 4-season＇ whole. The united state of these forces is controlled by the thinking and breathing motion, which is capable of changing from 3-, 2- and 1-dimensional states to a 0-dimensional state.

Strong metal‐support interaction boosting the catalytic activity of Au/TiO_(2) in chemoselective hydrogenation

Gold catalysts have been reported as highly effective catalysts in various oxidation reactions.However,for chemoselective hydrogenation reactions,gold‐based catalysts normally show much lowercatalytic activity than platinum group metals,even though their selectivities are excellent.Here,wereport that the chemoselective hydrogenation activity of 3‐nitrostyrene to 3‐vinylaniline overAu/TiO_(2)can be enhanced up to 3.3 times through the hydrogen reduction strategy.It is revealedthat strong metal‐support interaction,between gold nanoparticles(NPs)and TiO_(2)support,is introducedthrough hydrogen reduction,resulting in partial dispersion of reduced TiOx on the Au surface.The partially covered Au not only increases the perimeter of the interface between the gold NPs andthe support,but also benefits H_(2)activation.Reaction kinetic analysis and H_(2)‐D2 exchange reactionshow that H_(2)activation is the critical step in the hydrogenation of 3‐nitrostyrene to 3‐vinylaniline.Density functional theory calculations verify that hydrogen dissociation and hydrogen transfer arefavored at the interface of gold NPs and TiO_(2)over the hydrogen‐reduced Au/TiO_(2).This study providesinsights for fabricating highly active gold‐based catalysts for chemoselective hydrogenationreactions.

Catalytic performance enhancement by alloying Pd with Pt on ordered mesoporous manganese oxide for methane combustion

Ordered mesoporous Mn2O3 (meso‐Mn2O3) and meso‐Mn2O3‐supported Pd, Pt, and Pd‐Pt alloy x(PdyPt)/meso‐Mn2O3; x = (0.10?1.50) wt%; Pd/Pt molar ratio (y) = 4.9?5.1 nanocatalysts were prepared using KIT‐6‐templated and poly(vinyl alcohol)‐protected reduction methods, respectively.The meso‐Mn2O3 had a high surface area, i.e., 106 m2/g, and a cubic crystal structure. Noble‐metalnanoparticles (NPs) of size 2.1?2.8 nm were uniformly dispersed on the meso‐Mn2O3 surfaces. AlloyingPd with Pt enhanced the catalytic activity in methane combustion; 1.41(Pd5.1Pt)/meso‐Mn2O3gave the best performance; T10%, T50%, and T90% (the temperatures required for achieving methaneconversions of 10%, 50%, and 90%) were 265, 345, and 425 °C, respectively, at a space velocity of20000 mL/(g?h). The effects of SO2, CO2, H2O, and NO on methane combustion over1.41(Pd5.1Pt)/meso‐Mn2O3 were also examined. We conclude that the good catalytic performance of1.41(Pd5.1Pt)/meso‐Mn2O3 is associated with its high‐quality porous structure, high adsorbed oxygen species concentration, good low‐temperature reducibility, and strong interactions between Pd‐Pt alloy NPs and the meso‐Mn2O3 support.

Magnetization of GaAs Parabolic Quantum Dot by Variation Method

The magnetization of two interacting electrons confined in a quantum dot presented in a magnetic field had been calculated by solving the relative Hamiltonian using variational method. We had investigated the dependence of the magnetization on temperature, magnetic field strength and confining frequency. The singlet-triplet transitions in the ground state of the quantum dot spectra and the corresponding jumps in the magnetization curves had been shown. The comparisons show that our results are in very good agreement with reported works.

灌注桩桩端与桩侧土体相互作用试验研究

基于室内模型桩试验方法,结合灌注桩施工工艺对桩侧与桩端土体造成的影响,通过在桩侧设置泥皮与在桩端铺设石棉毡的方法分别控制桩侧与桩端土体承载条件,考察桩侧土体性质变化对桩端阻力的影响规律以及桩端土体性质改变时桩侧摩阻力的变化特征,进而揭示灌注桩桩端与桩侧土体相互强化的规律。

新中国成立以来中国共产党领导的制度优势与成功之道

新中国成立70年来,中国共产党领导的制度优势集中体现在以组织力为核心、以生产力为导向、以创造力为中心、以执行力为保障、以发展力为基石,塑造了组织的先进性、战略的前瞻性、决策的科学性、治理的绩效性以及发展的和平性这五大基本特征,而这些基本特征的累积叠加与相互强化,推动了中国共产党始终勇立潮头,敢于自我革新,不断带领中国人民从胜利走向更大的胜利。

Interface engineering of heterostructured electrocatalysts towards efficient alkaline hydrogen electrocatalysis

Boosting the alkaline hydrogen evolution and oxidation reaction(HER/HOR)kinetics is vital to practicing the renewable hydrogen cycle in alkaline media.Recently,intensive research has demonstrated that interface engineering is of critical significance for improving the performance of heterostructured electrocatalysts particularly toward the electrochemical reactions involving multiple reaction intermediates like alkaline hydrogen electrocatalysis,and the research advances also bring substantial non-trivial fundamental insights accordingly.Herein,we review the current status of interface engineering with respect to developing efficient heterostructured electrocatalysts for alkaline HER and HOR.Two major subjects—how interface engineering promotes the reaction kinetics and what fundamental insights interface engineering has brought into alkaline HER and HOR—are discussed.Specifically,heterostructured electrocatalysts with abundant interfaces have shown substantially accelerated alkaline hydrogen electrocatalysis kinetics owing to the synergistic effect from different components,which could balance the adsorption/desorption behaviors of the intermediates at the interfaces.Meanwhile,interface engineering can effectively tune the electronic structures of the active sites via electronic interaction,interfacial bonding,and lattice strain,which would appropriately optimize the binding energy of targeted intermediates like hydrogen.Furthermore,the confinement effect is critical for delivering high durability by sustaining high density of active sites.At last,our own perspectives on the challenges and opportunities toward developing efficient heterostructured electrocatalysts for alkaline hydrogen electrocatalysis are provided.

Fe3O4 Octahedral Colloidal Crystals

We present a facile and controllable method for the large-scale fabrication of highly-ordered octahedral Fe3O4 colloidal ＂single crystals＂ without the assistance of a substrate. Oleic acid is used to reduce the solubility of the nano-building blocks in colloidal solution and to induce a ＂crystallization＂ process. Our colloidal crystals are of multimicron size and show typical crystallographic characteristics. They have a very robust structure and can serve as a novel ordered magnetic mesoporous material with a relatively narrow pore size distribution. The sample possesses an extremely high Verwey transition temperature （Tv） of 100 K and a high saturation magnetization （Ms） of 86 emu/g at 5 K based on its good crystallinity, as well as the interparticle dipolar interaction behavior arising from its unique structure. Electrochemical measurements have demonstrated the excellent capacity of the mesoporous colloidal crystals when used in lithium-ion batteries.

Large exchange bias in magnetic shape memory alloys by tuning magnetic ground state and magnetic-field history

The exchange bias is of technological significance in magnetic recording and spintronic devices.Pursuing a large bias field is a long-term goal for the research field of magnetic shape memory alloys.In this work,a large bias field of 0.53 T is achieved in the Ni50Mn34In16-xFex(x=1,3,5)system by tuning the magnetic ground state(determined by the composition x)and the magnetic-field history(determined by the magnetic field HFCduring field cooling and the maximum field HMaxduring isothermal magnetization).The maximum volume fraction of the interfaces between the ferromagnetic clusters and antiferromagnetic matrix and the strong interfacial interaction are achieved by tuning the magnetic ground state and the magnetic-field history,which results in strong magnetic unidirectional anisotropy and the large exchange bias.Moreover,two guidelines were proposed to obtain the large bias field.Firstly,the composition with a magnetic ground state consisting of the dilute spin glass and the strong antiferromagnetic matrix is preferred to obtain a large bias field;secondly,tuning the magnetic-field history by enhancing HFCand reducing HMaxis beneficial to achieving large exchange bias.Our work provides an effective way for designing magnetically inhomogeneous compounds with large exchange bias.

Study of nanoscratching of polymers by using molecular dynamics simulations

Molecular dynamic simulations are performed to study the nanoscratching behavior of polymers.The effects of scratching depth,scratching velocity and indenter/polymer interaction strength are investigated.It is found that polymer material in the scratching zone around the indenter can be removed in a ductile manner as the local temperature in the scratching zone exceeds glass transition temperature Tg.The recovery of polymer can be more significant when the temperature approaches or exceeds Tg.The tangential force,normal force and friction coefficient increase as the scratching depth increases.A larger scratching velocity leads to more material deformation and higher pile-up.The tangential force and normal force are larger for a larger scratching velocity whereas the friction coefficient is almost independent of the scratching velocities studied.It is also found that stronger indenter/polymer interaction strength results in a larger tangential force and friction coefficient.