Energetic neutral atoms from a trans-Europa gas torus at Jupiter

The space environments--or magnetospheres--of magnetized planets emit copious quantities of energetic neutral atoms (ENAs) at energies between tens of electron volts to hundreds of kiloelectron volts (keV). These energetic atoms result from charge exchange between magnetically trapped energetic ions and cold neutral atoms, and they carry significant amounts of energy and mass from the magnetospheres. Imaging their distribution allows us to investigate the structure of planetary magnetospheres. Here we report the analysis of 50-80 keV ENA images of Jupiter's magnetosphere, where two distinct emission regions dominate: the upper atmosphere of Jupiter itself, and a torus of emission residing just outside the orbit of Jupiter's satellite Europa. The trans-Europa component shows that, unexpectedly, Europa generates a gas cloud comparable in gas content to that associated with the volcanic moon Io. The quantity of gas found indicates that Europa has a much greater impact than hitherto believed on the structure of, and the energy flow within, Jupiter's magnetosphere.     

Controlled exchange interaction between pairs of neutral atoms in an optical lattice

Ultracold atoms trapped by light offer robust quantum coherence and controllability, providing an attractive system for quantum information processing and for the simulation of complex problems in condensed matter physics. Many quantum information processing schemes require the manipulation and deterministic entanglement of individual qubits; this would typically be accomplished using controlled, state-dependent, coherent interactions among qubits. Recent experiments have made progress towards this goal by demonstrating entanglement among an ensemble of atoms confined in an optical lattice. Until now, however, there has been no demonstration of a key operation: controlled entanglement between atoms in isolated pairs. Here we use an optical lattice of double-well potentials to isolate and manipulate arrays of paired (87)Rb atoms, inducing controlled entangling interactions within each pair. Our experiment realizes proposals to use controlled exchange coupling in a system of neutral atoms. Although 87Rb atoms have nearly state-independent interactions, when we force two atoms into the same physical location, the wavefunction exchange symmetry of these identical bosons leads to state-dependent dynamics. We observe repeated interchange of spin between atoms occupying different vibrational levels, with a coherence time of more than ten milliseconds. This observation demonstrates the essential component of a neutral atom quantum SWAP gate (which interchanges the state of two qubits). Its 'half-implementation', the root SWAP gate, is entangling, and together with single-qubit rotations it forms a set of universal gates for quantum computation.     

Reduction of Faults in Software Testing by Fault Domination

Although mutation testing is one of the practical ways of enhancing test effectiveness in software testing, it could be sometimes infeasible in practical work for a large scale software so that the mutation testing becomes time-consuming and even in prohibited time. Therefore, the number of faults assumed to exist in the software under test should be reduced so as to be able to confine the time complexity of test within a reasonable period of time. This paper utilizes the concept of fault dominance and equivalence, which has long been employed in hardware testing, for revealing a novel way of reducing the number of faults assumed to hide in software systems. Once the number of faults assumed in software is decreased sharply, the effectiveness of mutation testing will be greatly enhanced and become a feasible way of software testing. Examples and experimental results are presented to illustrate the effectiveness and the helpfulness of the technology proposed in the paper.     

含锌离子的矿坑水混凝沉淀处理方法

根据铜坑矿矿坑水的水质特征,选取了复合混凝法对其进行处理,通过单因素及正交试验,研究了混凝剂和助凝剂配比、溶液pH值、搅拌速度和搅拌时间等因素对矿坑水中Zn2+去除效果的影响,确定了各因素的较佳水平.当聚合氯化铝(PAC)/聚丙烯酰胺(PAM)为2∶1,协同效应达到最好;pH值为9,搅拌速度为80 r.min-1,搅拌时间为10 min时,处理效果最佳.经实际水样处理试验结果表明:Zn2+去除率达93.9%,出水中Zn2+质量浓度满足国家排放标准要求.     

The Domination for Evaluation of the Contingent Claims by Nonlinear Generator

In this paper,through applying the result of backward stochastic differential equations,it investigates a domination for pricing of the contingent claims by the use of nonlinear infinitesimal generator of process X. This domination provides a guide for valuing the price of the position on the financial market.     

从人物描写看《我主沉浮》的现实意义和艺术价值

《我主沉浮》成功刻画了改革先锋赵安邦、腐败精英钱惠人、资本大鳄白原葳等人物形象。通过对作品的人物描写的具体分析,可以发现《我主沉浮》深刻的现实意义与较高的艺术价值。     

发酵秸秆吸附水中重金属离子性能研究

 生物吸附法是一种新兴的废水处理方法,高效廉价生物吸附剂的研发是生物吸附技术研究的关键之一。以甜高粱秸秆发酵产乙醇残渣（FSSR）为吸附剂,研究了其对Pb（Ⅱ）的吸附特性。研究结果表明,FSSR对Pb（Ⅱ）的吸附过程符合拟二级动力学模型,吸附过程是化学吸附过程。发酵后材料对Pb（Ⅱ）的吸附容量有显著提高,平衡时吸附容量由3.32 mg/g提高到6.92 mg/g。当温度由10℃升高到40℃时,FSSR对Pb（Ⅱ）最大吸附容量由5.92 mg/g提高到7.23 mg/g,等温吸附过程符合Langmuir模型。多元体系中FSSR对离子的选择性为Pb（Ⅱ）> Cu（Ⅱ）> Zn（Ⅱ）。发酵后材料有更多的活性官能团裸露在材料的表面,为吸附反应的发生提供了有利的条件,可以提高材料对金属离子的吸附容量。     

基于压力弹塑性变形中性层偏移模型的构建与验证

大截面棒材矫直过程中性层偏移明显,对二辊矫直辊辊型及棒材直线度的影响较大. 依据三点弯曲理论建立了棒材矫直过程中基于压力弹塑性变形的中性层偏移量理论计算模型,结合室温拉伸和弯曲试验,研究了棒材矫直过程中性层偏移规律. 结果表明:反弯半径和棒材力学性能对中性层偏移值的影响显著,反弯半径越小,则中性层偏移量越大;强度较低、塑性较强的材料,中性层偏移量较大. 通过弯曲试验,验证了该模型的可靠性及其适用范围.     

变压膜渗透空气分离制氮

在稳态膜渗透的基础上提出了一种新的非稳态渗透流程.该流程是一种循环操作过程,每一周期包含加压、抽真空以及排空三个阶段. 实验研究了加压时间、抽真空时间和排空时间对空气分离制氮的产品平均纯度、产率和回收率的影响,并与稳态渗透实验结果进行了比较. 结果表明,随着加压时间的延长,富氮气体的平均纯度、产率以及氮气回收率均会上升;延长抽真空时间可以提高富氮气体平均纯度,但会降低富氮产率和氮气回收率;适当延长排空时间可以提高富氮气体平均纯度、产率和氮气回收率,但排空时间过长将会导致富氮产率和氮气回收率下降. 本文提出的变压渗透过程能够得到比稳态渗透更高的富氮纯度,但富氮产率和回收率要低.     

Creation of ultracold molecules from a Fermi gas of atoms

Following the realization of Bose-Einstein condensates in atomic gases, an experimental challenge is the production of molecular gases in the quantum regime. A promising approach is to create the molecular gas directly from an ultracold atomic gas; for example, bosonic atoms in a Bose-Einstein condensate have been coupled to electronic ground-state molecules through photoassociation or a magnetic field Feshbach resonance. The availability of atomic Fermi gases offers the prospect of coupling fermionic atoms to bosonic molecules, thus altering the quantum statistics of the system. Such a coupling would be closely related to the pairing mechanism in a fermionic superfluid, predicted to occur near a Feshbach resonance. Here we report the creation and quantitative characterization of ultracold 40K2 molecules. Starting with a quantum degenerate Fermi gas of atoms at a temperature of less than 150 nK, we scan the system over a Feshbach resonance to create adiabatically more than 250,000 trapped molecules; these can be converted back to atoms by reversing the scan. The small binding energy of the molecules is controlled by detuning the magnetic field away from the Feshbach resonance, and can be varied over a wide range. We directly detect these weakly bound molecules through their radio-frequency photodissociation spectra; these probe the molecular wavefunction, and yield binding energies that are consistent with theory.     

中性磷类萃取剂从卤水中萃取锂的研究

为回收卤水中的金属锂 ,在 Fe Cl3存在的条件下 ,通过实验研究中性磷类萃取剂萃取锂的效果 ,并研究萃取时间、温度、萃取剂浓度、金属盐 (Mg2 ,Na ,K )浓度、酸度对TBP-煤油体系从高镁锂比的模拟卤水中萃取锂的影响规律。在实验中向高镁锂比的模拟卤水中添加 Fe Cl3,比较了中性磷类萃取剂 TBP、 DBBP和 TOPO萃取锂的效果 ,结果表明 TBP对锂有非常显著的萃取效果 ,而 DBBP和 TOPO的萃取能力则很弱。 TBP-煤油体系萃取锂时较优的萃取条件为 :萃取时间约为 2 0 min,温度为 2 0～ 2 5℃ ,[Fe3 ]/[L i ]为 1.5～ 2 .0 ,TBP体积分数为 5 0 %～ 70 % ,Mg Cl2 浓度大于 3m ol/ L ,p H值约为 2 ,在萃取锂之前应先将钠盐和钾盐分离析出。     

Flotation mechanisms of molybdenite fines by neutral oils

The flotation mechanisms of molybdenite fines by neutral oils were investigated through microflotation test,turbidity measurements,infrared spectroscopy,and interfacial interaction calculations.The results of the flotation test show that at pH 2-11,the floatability of molybdenite fines in the presence of transformer oil is markedly better than that in the presence of kerosene and diesel oil.The addition of transformer oil,which enhances the floatability of molybdenite fines,promotes the aggregation of molybdenite particles.Fourier transform infrared measurements illustrate that physical interaction dominates the adsorption mechanism of neutral oil on molybdenite.Interfacial interaction calculations indicate that hydrophobic attraction is the crucial force that acts among the oil collector,water,and molybdenite.Strong hydrophobic attraction between the oily collector and water provides the strong dispersion capability of the collector in water.Furthermore, the dispersion capability of the collector,not the interaction strength between the oily collectors and molybdenite,has a highly significant role in the flotation system of molybdenite fines.Our findings provide insights into the mechanism of molybdenite flotation.     

氧化石墨烯对水溶液中中性红的吸附行为

研究了氧化石墨烯(GO)对水溶液中染料中性红的吸附性能.考察了GO浓度、吸附时间等因素对吸附效果的影响,探究了动力学及热力学吸附规律.结果表明,GO对中性红具有显著、快速的去除能力,最大饱和吸附量可达到约900 mg/g,该吸附过程可用准二级吸附速率方程进行描述.不同温度下的热力学参数研究表明GO对中性红的吸附过程符合Langmuir等温吸附方程式,是一个自发、放热、熵增的过程.     

EAST中性束注入电流驱动的数值模拟研究

长脉冲高参数稳态运行是EAST的主要科学目标,因此大功率的辅助加热手段是必需的。文章基于EAST实验等离子体放电数据,针对EAST不同的中性束物理实验的需要,在不同的背景等离子体和中性束参数下模拟研究中性束注入的加热和电流驱动效果,包括不同的中性束注入功率和束能量等,模拟预测结果对开展EAST中性束注入实验研究具有参考意义。     

Hardness of materials: studies at levels from atoms to crystals

Based on the electron-holding energy per unit volume, we extend the concept of hardness to atomic stiffness, ionic stiffness and bond hardness, investigating the nature of material hardness at these three levels. We find that the stiffness of isolated atoms or ions has no direct connection with the hardness of materials, whereas material hardness is directly related to bond hardness, which is essentially determined by the electron-holding energy of its constituent chemical bonds per unit volume. We establish a model for identifying the hardness of materials on the basis of bond hardness. This work offers a deeper understanding of the nature of material hardness at the atomic level, and provides a practical guide in the search for new superhard materials. Supported by National Natural Science Foundation of China (Grant No. 20471012), Program for New Century Excellent Talents in University (Grant No. NCET-05-0278) and Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200322)     

金属离子的反相微胶团萃取研究

研究了用正己烷－环己醇、异辛烷－正己醇作萃取溶剂,铬天青Ｓ作萃取剂,加入Ｎ－氯代十六烷基吡啶、十六烷基三甲基溴化铵等阳离子表面活性剂,在ＨＮＯ３和ＨＣｌ介质中Ｆｅ（Ⅱ）,Ｌａ（Ⅱ）,Ｃｕ（Ⅱ）和Ｐｄ（Ⅱ）等金属离子的反相微胶团萃取行为。讨论了不同浓度的电解质溶液和酸溶液对有机相中金属离子进行反萃取的影响,实现了Ｆｅ（Ⅲ）－Ｃｕ（Ⅱ）,Ｌａ（Ⅲ）－Ｃｕ（Ⅱ）等金属离子间的定量萃取分离。     

Chemical identification of individual surface atoms by atomic force microscopy

Scanning probe microscopy is a versatile and powerful method that uses sharp tips to image, measure and manipulate matter at surfaces with atomic resolution. At cryogenic temperatures, scanning probe microscopy can even provide electron tunnelling spectra that serve as fingerprints of the vibrational properties of adsorbed molecules and of the electronic properties of magnetic impurity atoms, thereby allowing chemical identification. But in many instances, and particularly for insulating systems, determining the exact chemical composition of surfaces or nanostructures remains a considerable challenge. In principle, dynamic force microscopy should make it possible to overcome this problem: it can image insulator, semiconductor and metal surfaces with true atomic resolution, by detecting and precisely measuring the short-range forces that arise with the onset of chemical bonding between the tip and surface atoms and that depend sensitively on the chemical identity of the atoms involved. Here we report precise measurements of such short-range chemical forces, and show that their dependence on the force microscope tip used can be overcome through a normalization procedure. This allows us to use the chemical force measurements as the basis for atomic recognition, even at room temperature. We illustrate the performance of this approach by imaging the surface of a particularly challenging alloy system and successfully identifying the three constituent atomic species silicon, tin and lead, even though these exhibit very similar chemical properties and identical surface position preferences that render any discrimination attempt based on topographic measurements impossible.