Bound States of Repulsing Adsorbed Atoms

JETP Letters - The interaction between two slow atoms adsorbed on the surface is considered. It is shown that, similar to Efimov states of three particles, this system has a bound state at any sign...     

基于多通道联合收发技术的5G传统室分系统错层部署方案研究

本文通过对多通道联合收发技术的研究,探索5G室内分布系统错层部署建设的新模式,在不改变原有LTE传统系统网络结构的前提下,快速实现单双路系统能力的提升,极大提升了传统室分5G网络系统覆盖和性能.为了更好地验证错层部署的覆盖效果,选取了某大厦物业点进行了试点建设,为后续大规模开展5G室内分布系统建设提供了重要参考.     

场发射阵列硅基底类型对去铝牺牲层工艺的影响

研究了Spindt场发射阵列铝牺牲层工艺中不同硅基底类型对尖锥的影响,结果表明,在有栅极(Ti-W)和无栅极情况下,p-Si基底的场发射尖锥阵列都会被腐蚀破坏,而n-Si衬底的尖锥形貌完好.这是由于基底材料与尖锥材料之间形成的接触电位差,使高逸出功的p-Si基底与Mo尖锥形成Mo为阳极、p-Si为阴极而导致Mo尖锥被腐蚀;低逸出功n-Si基底则避免了这种现象的发生.     

A Bismuth-Based Zeolitic Organic Framework with Coordination-Linked Metal Cages for Efficient Electrocatalytic CO2 Reduction to HCOOH

Zeolitic metal–organic frameworks (ZMOFs) have emerged as one of the most promsing catalysts for energy conversion, but they suffer from either weak bonding between metal-organic cubes (MOCs) that decrease their stability during catalysis processes or low activity due to inadequate active sites. In this work, through ligand-directing strategy, we successfully obtain an unprecedented bismuth-based ZMOF (Bi-ZMOF) featuring a ACO topological crystal structure with strong coordination bonding between the Bi-based cages. As a result, it enables efficient reduction of CO₂ to formic acid (HCOOH) with Faradaic efficiency as high as 91 %. A combination of in situ surface-enhanced infrared absorption spectroscopy and density functional theory calculation reveals that the Bi−N coordination contributes to facilitating charge transfer from N to Bi atoms, which stabilize the intermediate to boost the reduction efficiency of CO₂ to HCOOH. This finding highlights the importance of the coordination environment of metal active sites on electrocatalytic CO₂ reduction. We believe that this work will offer a new clue to rationally design zeolitic MOFs for catalytic reaction     

Phosphorothioated DNA Engineered Liposomes as a General Platform for Stimuli-Responsive Cell-Specific Intracellular Delivery and Genome Editing

Intracellular protein delivery is highly desirable for protein drug-based cell therapy. Established technologies suffer from poor cell-specific cytosolic protein delivery, which hampers the targeting therapy of specific cell populations. A fusogenic liposome system enables cytosolic delivery, but its ability of cell-specific and controllable delivery is quite limited. Inspired by the kinetics of viral fusion, we designed a phosphorothioated DNA coatings-modified fusogenic liposome to mimic the function of viral hemagglutinin. The macromolecular fusion machine docks cargo-loaded liposomes at the membrane of target cells, triggers membrane fusion upon pH or UV light stimuli, and facilitates cytosolic protein delivery. Our results showed efficient cell-targeted delivery of proteins of various sizes and charges, indicating the phosphorothioated DNA plug-in unit on liposomes could be a general strategy for spatial-temporally controllable protein delivery both in vitro and in vivo.     

Expanded Conformations of Monomeric Tau Initiate Its Amyloidogenesis**

Understanding early amyloidogenesis is key to rationally develop therapeutic strategies. Tau protein forms well-characterized pathological deposits but its aggregation mechanism is still poorly understood. Using single-molecule force spectroscopy based on a mechanical protection strategy, we studied the conformational landscape of the monomeric tau repeat domain (tau-RD_244-368). We found two sets of conformational states, whose frequency is influenced by mutations and the chemical context. While pathological mutations Δ280K and P301L and a pro-amyloidogenic milieu favored expanded conformations and destabilized local structures, an anti-amyloidogenic environment promoted a compact ensemble, including a conformer whose topology might mask two amyloidogenic segments. Our results reveal that to initiate aggregation, monomeric tau-RD_244-368 decreases its polymorphism adopting expanded conformations. This could account for the distinct structures found in vitro and across tauopathies.     

Stimulated Raman scattering influenced by concentration,fluorescence profile and bandwidth of β‐carotene in liquid‐core optical fiber

We demonstrated stimulated Raman scattering (SRS) of carbon disulfide (CS₂) influenced by β‐carotene in a liquid‐core optical fiber (LCOF). Owing to the double fluorescence characteristics and large third‐order optical nonlinearity of β‐carotene, the high‐order Stokes lines, such as the seventh‐order Stokes line of CS₂, can be observed at a relatively low input‐laser power. The thresholds of Stokes lines lowered with the addition of the carotenoid when the concentration of solution was within 10⁻¹² and 10⁻⁷ mol/L; the threshold increments and intensities of Stokes lines were correlative with the fluorescence profile of β‐carotene: when the fluorescence intensity of the wavenumber region on the spectrum was high, the Stokes line intensity was also high and its threshold increment was small, and vice versa. These results are expected to be worthy of the applications on the tunable laser and the seeding laser. Copyright © 2009 John Wiley & Sons, Ltd.     

弱相互作用费米气体的相对论顺磁性

通过考虑单粒子的相对论能量并且应用量子统计方法，研究弱磁场中弱相互作用费米气体的相对论顺磁性，求解相对论性的最可几磁化率及平均磁化率，讨论相对论效应对最可几磁化率的影响，给出相对论性的粒子数的临界值. 结果显示, 与非相对论情况比较，当 时, 相对论情况下的最可几磁化率和粒子数的临界值都没有变化. 当 时，相对论效应使系统呈现顺磁性容易，而且相对论效应增加磁化率，同时也放大了相互作用对磁化率的影响.     

ZnO纳米棒阵列提高发光二极管光抽取效率的研究

为了提高大功率LED的光抽取效率,采用溶胶-凝胶法、水热生长法的两步生长工艺在大功率红光发光二极管(LEDs)表面制作ZnO纳米棒阵列结构进行研究.利用ZnO纳米棒形成的光波导,ZnO纳米棒侧面为辅助出光面,提高了LED芯片的光输出效率.测试表明,所生长的ZnO纳米棒分布密度均匀,形貌一致;与未制作ZnO纳米棒前相比较...     

Vibration-induced energy relaxation in two-level system

Energy decay in a general two-level electronic system coupled to a vibrational harmonic mode interacting with a thermal bath is studied theoretically. The model assumes a general form of the off-diagonal elements (in the electronic basis) of the vibrational-electronic interaction. The cases for constant, linear, and quadratic dependence with respect to the vibrational displacement are investigated. For short-time regime, fast oscillations corresponding to a coherent energy exchange between electrons and vibrations appear. Their frequency Ω corresponds to the energy difference (ħΩ) between electronic levels. Additionally, for the case of linear or quadratic coupling, the amplitude modulation of the oscillations with the frequency ω equal to that of vibrational motion is found.