No Spin-Localization Phase Transition in the Spin-Boson Model without Local Field

We explore the spin-boson model in a special case, i.e., with zero local field. In contrast to previous studies, we find no possibility for quantum phase transition （QPT） happening between the localized and delocalized phases, and the behavior of the model can be fully characterized by the even or odd parity as well as the parity breaking, instead of the QPT, owned by the ground state of the system. The parity breaking mentioned in our case is completely different from the spontaneously broken symmetry relevant to the conventionally defined QPT in previous studies. Our analytical treatment about the eigensolution of the ground state of the model presents for the first time a rigorous proof of no- degeneracy for the ground state of the model, which is independent of the bath type, the degrees of freedom of the bath and the calculation precision. We argue that the QPT mentioned previously appears due to incorrect employment of the ground state of the model and/or unreasonable treatment of the infrared divergence existing in the spectral functions for Ohmic and sub-Ohmic dissipations.     

松辽盆地陆相生油母质的类型与演化模式

本文利用综合指标参数对松辽盆地的干酪根进行了分类,把油气形成划分为四个阶段,建立了大型湖盆不同类型干酪根分布与油气演化模式。特别指出:大型富营养湖泊,在大面积长期继承性深水构造凹陷环境中,快速湖进式非补偿条件下形成的生油岩,生油潜力大;迭合腐泥型(Ⅰ类)干酪根的热演化和油气形成特征,有别于前人提出的油气演化一般模式。预测盆地仍有良好的勘探远景。     

La掺杂Bi-2201单晶中宏观相分离迹象的发现及研究

在对系列Ｌａ 掺杂的Ｂｉ２Ｓｒ２ － ｘＬａｘＣｕＯ６ ＋ δ单晶的研究中,我们发现在极度Ｌａ 掺杂（ 空穴极度欠掺杂） 的样品中有高达３６Ｋ 的超导相出现．Ｘ 射线衍射图（ＸＲＤ） 和电镜照片都表明这种极度空穴欠掺的样品有很好的单相性,从而排除了样品化学不纯的可能．另外,对这种样品进行脱氧处理后,此超导电性相应消失,说明了这种高Ｔｃ 的超导电性是由活动性空穴掺杂引起的．虽然对相应样品在正常态的磁测量没有测出反铁磁峰（Ｎｅｅｌ 峰） ,但对系列样品的拉曼散射研究发现样品随着Ｌａ 含量的增多,其反铁磁交换作用明显加强．所以,我们认为这种高Ｔｃ 超导电性的出现是在Ｂｉ２２０１ 体系中存在宏观相分离的明显迹象     

PHASE SEPARATION AND JOSEPHSON-COUPLING ORIGIN FOR THE ANOMALOUS Hc2 BEHAVIOR IN OVERDOPED Bi2Sr2-xLaxCuO6+δ CRYSTALS

Hole-overdoped Bi₂Sr_2-xLa_xCuO_6+δ single crystals with two coexistent superconducting transitions have been intensively studied by measuring the dc magnetic susceptibility. It is found that the coexistence of these two phases cannot be attributed to any chemical or vortex dynamical effect but to some intrinsic driving force, such as the electronic-driven phase separation. Furthermore, the upper critical fields of the two phases behave in a rather different way; that is, one of them shows a "normal H_c2 behavior" which can be described by the critical fluctuation theory, while the other exhibits an "anomalous H_c2 behavior" and can be well explained by a recent theory based on an assumption of a Josephson-coupling origin, indicating a strong evidence of Josephson-coupling origin for the upward curvature of the so-called H_c2 in high T_c superconductors.     

新修正偶应力层合板理论中的几个基本假设对自由振动计算的影响

基于新修正偶应力理论,在对微细观尺度的复合材料层合梁/板进行力学响应计算时,往往采用一系列假设来简化模型。现有文献都全部或部分应用了这些假设,但对这些假设是否会对计算结果造成影响尚未进行充分讨论分析。本文建立了未经简化的新修正偶应力Reddy层合板模型,并对其自由振动进行了分析。通过数值算例的对比,讨论了常用的几个简化假设对微细观复合材料四边简支方板自振频率的影响以及适用范围。算例结果表明,常用的几个简化假设对于微尺度层合薄板自由振动的影响很小,对于厚板的低阶频率影响也很小,但对厚板的高阶频率影响显著。     

基于修正偶应力和高阶剪切变形理论的变截面微梁的自由振动

基于修正偶应力和高阶剪切理论建立了仅含有一个尺度参数的Reddy变截面微梁的自由振动模型,研究了变截面微梁自由振动问题的尺度效应和横向剪切变形对自振频率计算的影响。基于哈密顿原理推导了动力学方程与边界条件,并采用微分求积法求解了各种边界条件下的自振频率。算例结果表明,基于偶应力理论预测的变截面微梁的自振频率均大于经典梁理论的预测结果,即捕捉到了尺度效应。另外,梁的几何尺寸与尺度参数越接近,尺度效应就越明显,而梁的长细比越小,横向剪切变形对自振频率的影响就越明显。     

Soft x-ray spectroscopy for probing electronic and chemical states of battery materials

The formidable challenge of developing high-performance battery system stems from the complication of battery operations, both mechanically and electronically. In the electrodes and at the electrode–electrolyte interfaces, chemical reactions take place with evolving electron states. In addition to the extensive studies of material synthesis, electrochemical, structural, and mechanical properties, soft x-ray spectroscopy provides unique opportunities for revealing the critical electron states in batteries. This review discusses some of the recent soft x-ray spectroscopic results on battery binder,transition-metal based positive electrodes, and the solid-electrolyte-interphase. By virtue of soft x-ray's sensitivity to electron states, the electronic property, the redox during electrochemical operations, and the chemical species of the interphases could be fingerprinted by soft x-ray spectroscopy. Understanding and innovating battery technologies need a multimodal approach, and soft x-ray spectroscopy is one of the incisive tools to probe the chemical and physical evolutions in batteries.     

活性/可控自由基聚合制备奎宁分子印迹微球及识别性能研究

以奎宁分子为模板,甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,二硫代四乙基秋兰姆(TED)为活性/可控引发剂,将可逆加成—断裂链转移自由基聚合与沉淀聚合相结合,制备微米级的球形奎宁分子印迹聚合物。并用扫描电镜和激光粒度扫描对聚合物粒子进行表征,结果显示,活性/可控聚合制备的分子印迹聚合物呈均匀的球形,其平均粒径最大可达2.3μm。对不同底物的结合实验表明,与传统沉淀聚合物相比,该分子印迹聚合物表现出更高的络合容量和分子选择性。     

过量La掺杂的Bi—2201单晶的超导电性

在极度Ｌａ掺杂的Ｂｉ２Ｓｒ２－ｘＬａｘＣｕＯ６＋ｙ单晶中发现Ｔｃ高达３６Ｋ的超导相。Ｘ射线衍射（ＸＲＤ图和劳埃斑点实验都显示单晶具有很好的质量。ＥＤＸ分析结果和由ＸＲＤ得到的单晶ｃ轴长度均证实单晶处于极度Ｌａ掺杂的区域。一般来说，处于如此高Ｌａ掺杂区域的Ｂｉ－２２０１体系不表现出超导电性。因为我们的样品曾在Ｏ２中６８０℃退火１０小时，而且极度Ｌａ掺杂会导致长程反铁磁有序背景。所以我们将这种高Ｔｃ的     

TYPE AND EVOLUTION MODEL OF CONTINENTAL KEROGEN IN THE SONGLIAO BASIN

Based on some composite indices, this paper proposes a classification of kerogen in theSongliao Basin and the four stages of hydrocarbon formation. A model of the evolution ofhydrocarbons in a large lake basin different from the model previously suggested ispresented. It is pointed out hi this paper that in a long subsiding, deep-water structural de-pression of a large eutrophic lake, the source rock formed under rapid, non-compensatoryconditions has the highest potential for petroleum. The thermal evolution of "combined"sapropelic kerogen (type Ⅰ) and the characteristics of petroleum formation are illustrated,The authors predict that the Songliao Basin is promising for further exploration.