Cavity QED with semiconductor nanocrystals

We report on a strongly coupled cavity quantum electrodynamic (CQED) system consisting of a CdSe nanocrystal coupled to a single photon mode of a polymer microsphere. The strong exciton-photon coupling is manifested by the observation of a cavity mode splitting variant Planck's over 2piOmega(exp) between 30 und 45 microeV and photon lifetime measurements of the coupled exciton-photon state. The single photon mode is isolated by lifting the mode degeneracy in a slightly deformed microsphere cavity and addressing it by high-resolution imaging spectroscopy. This cavity mode is coupled to a localized exciton of an anisotropically shaped CdSe nanocrystal that emits highly polarized light in resonance to the cavity mode and that was placed in the maximum electromagnetic field close to the microsphere surface. The exciton confined in the CdSe nanorod exhibits an optical transition dipole moment much larger than that of atoms, the standard system for CQED experiments, and a low-temperature homogeneous line width much narrower than the high-Q cavity mode width. The observation of strong coupling in a colloidal semiconductor nanocrystal-cavity system opens the way to study fundamental quantum-optics phenomena and to implement quantum information processing concepts that work in the visible spectral range and are based on solid-state nanomaterials.     

Highly ordered graphene architectures by duplicating melamine sponges as a three-dimensional deformation-tolerant electrode

In this study, macroscopic graphene-wrapped melamine foams (MF-G) were fabricated by an MF-templated layer-by-layer (LBL) assembly using graphene oxide as building blocks, followed by solution-processed reduction. By concisely duplicating sponge-like, highly ordered three-dimensional architectures from MF, the resulting MF-G with an interconnected graphene-based scaffold and tunable nanostructure was explored as compressible, robust electrodes for efficient energy storage. A thin layer of pseudocapacitive polypyrrole (PPy) was then attached and uniformly coated on MF-G, resulting in a well-defined core–double-shell configuration of the MF-G-PPy ternary composite sponges. The as-assembled devices exhibited enhancement of supercapacitor performance, with a high specific capacitance of 427 F·g^?1 under a compressive strain of 75% and an excellent cycling stability with only 18% degradation after 5,000 charge–discharge cycles. Besides, the MF-G-PPy electrode maintained stable capacitance up to 100 compression–release cycles, with a compressive strain of 75%. These encouraging results thus provide a new route towards the low-cost, easily scalable fabrication of lightweight and deformation-tolerant electrodes.

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Les phases SrLa2Al2O7 et SrGd2Al2O7

SrLa₂Al₂O₇ and SrGd₂Al₂O₇ belong to the structural type Sr₃Ti₂O₇. In SrGd₂Al₂O₇ strontium and gadolinium occupy respectively the 12 and 9 coordinated sites, whereas in SrLa₂Al₂O₇ the homologous cations are statistically distributed. The fluorescence spectra of both phases activated by Eu³⁺ ions show that the only possible position of Eu³⁺ is the 9 coordinated site.     

数字签名应用标准化初步模型

本文分析了数字签名的优势和潜力,指出了数字签名技术的广阔应用前景,同时阐明了建立相关标准的重要性,并且提出了一个数字签名技术应用的通用的模型.     

节能型低噪声卡式双吹风机盘管

介绍了节能型低噪声卡式双吹风机盘管机组采用的新型卡式双吹风结构,其特点是采用了U形单排管换热器、下置式风机组件、波浪形过滤网等部件。通过对这些部件的合理布置,大幅度降低机组能耗及噪声,保证了产品输入功率及噪声指标,解决了传统盘管在实际运行时风量小的问题,有效提高了空调房间的舒适性。     

刚性基础下柔性桩桩侧摩阻力及有效桩长的研究

复合地基加固软土地基应用广泛,但对其加固机理的认识还并不全面,对摩阻力的分布规律也有待研究。基于桩土顶部位移相等原理,利用Mindlin位移解推导了刚性基础下柔性桩摩阻力和桩轴力的分布形式,得到最大摩阻力及其深度的计算公式。对摩阻力分布形式进行简化,并在此基础上推导出有效桩长的计算公式。     

前驱体酸碱添加剂对溶胶凝胶法制备LiFePO4的影响

溶胶凝胶法作为一种常见的软化学方法用于LiFePO4锂离子正极材料的制备。通过在前驱体中添加盐酸或者氨水，考察不同酸碱添加剂对LiFePO4性能的影响。X射线衍射分析（XRD）和扫描电子显微镜（SEM）用于材料物相及形貌的分析和表征，通过正极材料在空气中加热前后质量差计算得到正极材料中的碳含量。加入盐酸的样品的颗粒尺寸、碳含量及可逆容量得到较为明显的改善，在低充放速率下达到140mAh／g的容量。     

Quantification of Tafel coefficients according to passive/active state of steel carbonation‐induced corrosion in concrete

Statistical quantification of Tafel coefficients is investigated in this study for isolated steel rebar embedded in concrete. The survey is supported by a wide experimental campaign carried out earlier to characterize the passive and active states of carbonation‐induced corrosion of steel. Electrochemical measurements (polarization resistance, corrosion potential, Tafel coefficients) and gravimetric estimations of iron loss were regularly conducted over 417 days on 108 concrete specimens. The statistical analysis reveals that the mean value of Tafel coefficients, both cathodic and anodic, is higher under active corrosion, which seems to contradict the general tendency found for chloride‐induced corrosion, while their coefficient of variation is smaller. The statistical inference was based on the first step of distributions fitting the experimental data and then on the second step of goodness‐of‐fit tests. The most suitable of the distributions proposed were the Burr, Rayleigh, and Gamma distributions. A similar analysis was made for the corrosion potential and polarization resistance. The findings of the study will be valuable for probabilistic approaches to corrosion where probabilistic distributions are required.     

Physical Characteristics of Friction Processes in a Columnar Approach-Separation Model with Tangential Force

Protection of Metals and Physical Chemistry of Surfaces - Three-dimensional molecular dynamics (MD) simulation is conducted to understanding the dynamics processes of atomic-scale friction, which...     

Leukotriene B4 stimulation of an early elevation of phosphatidic acid mass in human neutrophils

The signal transduction pathway of leukotriene B₄ involves phospholipase D activation in cytochalsin B-primed neutrophils, but leukotriene B₄ stimulation of increased phosphatidic acid mass in neutrophils has not been demonstrated. Employing the NIH Image program, we have examined the effect of leukotriene B₄ on phosphatidic acid mass in human neutrophils incubated with or without cytochalasin B. Our results show that 0.15 μM leukotriene B₄ without cytochalasin B was capable of increasing phosphatidic acid mass in neutrophils by 2-fold after 5 s, 2.5-fold after 1 min, and 2-fold after 5 min incubation. Leukotriene B₃, leukotriene B₄, and leukotriene B₅ were equipotent stimuli for phosphatidic acid mass elevation. Leukotriene B₄ induced phosphatidylethanol formation at the expense of phosphatidic acid in cells preincubated with 0.25–1% ethanol, indicating phospholipase D activation. Cytochalasin B enhanced leukotriene B₄ stimulation of phosphatidic acid mass elevation and phosphatidylethanol formation. There were no measurable changes in 1,2-diglyceride mass after 5 s, but a 1.7-fold increase occurred after 1 min and declined thereafter. Leukotriene B₄ stimulation of [³H]glycerol incorporation into phosphatidic acid, diglyceride and phosphatidylinositol was detectable after a 1-min incubation, suggesting increasedde novo synthesis of these lipids. These results suggest that leukotriene B₄ stimulation of phospholipase D activity contributes to part of the early increased phosphatidic acid mass and that combined actions of stimulated phospholipases C and D, andde novo phosphatidic acid synthesis contribute to the total increased phosphatidic acid mass.