Sodiation Of Hard Carbon: How Separating Enthalpy And Entropy Contributions Can Find Transitions Hidden In The Voltage Profile

Sodium-ion batteries (NIBs) utilize cheaper materials than lithium-ion batteries (LIBs) and can thus be used in larger scale applications. The preferred anode material is hard carbon, because sodium cannot be inserted into graphite. We apply experimental entropy profiling (EP), where the cell temperature is changed under open circuit conditions. EP has been used to characterize LIBs; here, we demonstrate the first application of EP to any NIB material. The voltage versus sodiation fraction curves (voltage profiles) of hard carbon lack clear features, consisting only of a slope and a plateau, making it difficult to clarify the structural features of hard carbon that could optimize cell performance. We find additional features through EP that are masked in the voltage profiles. We fit lattice gas models of hard carbon sodiation to experimental EP and system enthalpy, obtaining: 1. a theoretical maximum capacity, 2. interlayer versus pore filled sodium with state of charge.     

初中化学“溶液”的项目式教学*——白砂糖的梦想之路

以“白砂糖的梦想之路”为项目学习主题,呈现了初中化学“溶液”的项目教学案例。基于棒棒糖的制作过程开发了系列学习任务,有助于学生在真实的问题情境中发展核心素养和构建灵活的知识基础。     

真空紫外光电离质谱技术进展及其在快速分析中的应用

真空紫外光电离源(VUV-PI)是一种普适性的质谱软电离源,真空紫外光电离质谱谱图无碎片、易解析、灵敏度高,适合于在线快速分析。真空紫外光电离质谱根据分析对象不同可以直接采用单光子电离或添加掺杂剂实现化学电离,能实现气、液、固体分析,也可实现成像分析。该文介绍了真空紫外光电离源的电离原理、光源类型,分析了光电离质谱灵敏度的影响因素及其技术改进措施,并阐述了真空紫外光电离质谱技术在环境污染物、化工产物在线分析、国家安全分析以及生物医学分析中的相关应用研究。最后,总结了真空紫外光电离源的优缺点,并对真空紫外光电离技术在性能和应用方面的发展前景进行了展望。     

Effects of Polydispersity on the Phase Behavior of Additive Hard Spheres in Solution

The ability to separate enzymes, nucleic acids, cells, and viruses is an important asset in life sciences. This can be realised by using their spontaneous asymmetric partitioning over two macromolecular aqueous phases in equilibrium with one another. Such phases can already form while mixing two different types of macromolecules in water. We investigate the effect of polydispersity of the macromolecules on the two-phase formation. We study theoretically the phase behavior of a model polydisperse system: an asymmetric binary mixture of hard spheres, of which the smaller component is monodisperse and the larger component is polydisperse. The interactions are modelled in terms of the second virial coefficient and are assumed to be additive hard sphere interactions. The polydisperse component is subdivided into sub-components and has an average size ten times the size of the monodisperse component. We calculate the theoretical liquid–liquid phase separation boundary (the binodal), the critical point, and the spinodal. We vary the distribution of the polydisperse component in terms of skewness, modality, polydispersity, and number of sub-components. We compare the phase behavior of the polydisperse mixtures with their concomittant monodisperse mixtures. We find that the largest species in the larger (polydisperse) component causes the largest shift in the position of the phase boundary, critical point, and spinodal compared to the binary monodisperse binary mixtures. The polydisperse component also shows fractionation. The smaller species of the polydisperse component favor the phase enriched in the smaller component. This phase also has a higher-volume fraction compared to the monodisperse mixture.     

Calculation of the photon spectrum radiated by a planarly channeled positron bunch with allowance for the medium polarization

The radiation spectrum of a photon bunch with the energy E = mc ²γ = 4 GeV channeled in the (110) plane of a diamond single crystal is calculated numerically, taking into account the inhomogeneous polarization of the medium. Features of the spectrum in the extreme soft region of frequencies are obtained. Characteristics of the calculated spectrum are in agreement with the experimental data obtained in the hard region of frequencies.     

Generation of a four-qubit cluster state for atoms in a thermal cavity

We propose two schemes for generating a four-atom cluster state in a thermal cavity. With the assistant of a strong classical field the photon-number-dependent parts in the effective Hamiltonian are canceled. Thus the schemes are insensitive to the thermal field. The schemes can also be used to generate the cluster state for the trapped ions in thermal motion.     

Generation of entanglement via atomic coherence in a two-mode three-level cascade atomic system

The generation of continuous variable entanglement via atomic coherence in a two-mode three-level cascade atomic system is discussed according to the entanglement criterion proposed by Duan et al. [Phys. Rev. Lett. 84, 2722 (2000)]. Atomic coherence between the top and bottom levels is induced with two photons of a strong external pump field. It shows that entanglement for the two-mode field in the cavity can be generated under certain conditions. Moreover, by means of the input-output theory, we show that the two-mode entanglement could also be approached at the output.     

Upgrade of beamline BL08B at Taiwan Light Source from a photon‐BPM to a double‐grating SGM beamline

During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam‐position monitor (BPM) to a testing beamline and a single‐grating beamline that enables experiments to record X‐ray photo‐emission spectra (XPS) and X‐ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X‐ray photon energies in the range 300–1000 eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano‐fabrication and topological thin films are increasing. The basic spherical‐grating monochromator beamline was again upgraded by adding a second grating that delivers photons of energy from 80 to 420 eV. Four end‐stations were designed for experiments with XPS, XAS, interstellar photoprocess systems (IPS) and extreme‐ultraviolet lithography (EUVL) in the scheduled beam time. The data from these experiments show a large count rate in core levels probed and excellent statistics on background normalization in the L‐edge adsorption spectrum.     

NaN_3对玉米萌发过程中超弱光子辐射的影响

为了解读植物种子萌发过程中超弱光子辐射信息的生物学意义,采用呼吸抑制剂NaN3处理萌发玉米种子,跟踪测量和分析了玉米种子萌发过程中超弱光子辐射中自发光子辐射和外界光诱导的延迟光子辐射的变化规律,同时研究了萌发玉米种子鲜质量的变化.结果发现,NaN3同步抑制了萌发玉米自发光子辐射和鲜质量的增长,造成萌发玉米延迟光子辐射的初始光子数和延迟光子辐射积分强度大幅度降低,相干时间减小.机理分析表明,NaN3对呼吸代谢电子传递链的抑制造成的自由基反应减弱是萌发玉米自发光子辐射减小的原因,自发光子辐射强度可以作为玉米萌发状态的信号,延迟光子辐射动力学参数的大小可以表征萌发玉米呼吸代谢的强弱,相干时间是种子细胞组织序性的量度,通过对萌发种子超弱光子辐射的采集和分析可以实现对萌发种子细胞代谢和功能状态变化的灵敏和无损检测.     

AN INDIVIDUAL‐BASED MODEL FOR FERAL HOGS IN GREAT SMOKY MOUNTAINS NATIONAL PARK

The expansion of feral hog (Sus scrofa) populations in the United States has resulted in increased efforts to develop and implement control strategies designed to minimize the impacts done by this invasive species. We describe an individual‐based model for feral hogs in Great Smoky Mountains National Park (GSMNP). The objectives of the model are to provide an understanding of the population dynamics of this feral hog population and to determine the efficacy of the annual harvest as a population control method. Results suggest that the dynamics of the population are driven by fall hard mast production and the GSMNP harvests currently limit growth of the population, but these control efforts have not reduced the population.