Controllable double-well magneto-optic atom trap with a circular current-carrying wire

We propose a controllable double-well magneto-optic trap (MOT) for neutral atoms that uses a circular current-carrying wire and a biased magnetic field. One can cause the proposed double-well trap to evolve continually into a single-well trap by reducing the current in the wire or increasing the bias field. We estimate that in a weak intensity approximation a cold atomic sample with a temperature of approximately 300 K and a number of approximately 10(6) atoms can be stored in each MOT. One can control the number of trapped atoms by changing the current in the wire.     

Facile synthesis of CoWO<Subscript>4</Subscript>/RGO composites as superior anode materials for lithium-ion batteries

In this paper, a facile method has been developed to synthesize supported CoWO₄ on the reduced graphene oxide (RGO) as high-performance anode material for Li-ion batteries. The composites with cuboid-like CoWO₄ nanoparticles were prepared by directly adding graphene oxide into the precursor solution followed by a hydrothermal treatment. Different analytical methods like high-resolution TEM, XRD, TGA, and XPS characterizations were employed to illustrate structural information of the as-prepared CoWO₄ and CoWO₄/RGO composites. In addition, the Li-ion battery performance using the composites as anode materials was also discussed based on the detailed galvanostatic charge-discharge cycling tests. The result shows that the specific capacity of the as-prepared CoWO₄/RGO composites can reach 533.3 mAh g^?1 after 50 cycles at a current density of 100 mA g^?1. During the whole cyclic process, the coulombic efficiency was maintained higher than 90%. Therefore, CoWO₄, as an environment-friendly and cost-effective anode material, has promising potential for Li-ion batteries.     

Charge Neutralization Drives the Shape Reconfiguration of DNA Nanotubes

Reconfiguration of membrane protein channels for gated transport is highly regulated under physiological conditions. However, a mechanistic understanding of such channels remains challenging owing to the difficulty in probing subtle gating‐associated structural changes. Herein, we show that charge neutralization can drive the shape reconfiguration of a biomimetic 6‐helix bundle DNA nanotube (6HB). Specifically, 6HB adopts a compact state when its charge is neutralized by Mg²⁺; whereas Na⁺ switches it to the expanded state, as revealed by MD simulations, small‐angle X‐ray scattering (SAXS), and FRET characterization. Furthermore, partial neutralization of the DNA backbone charges by chemical modification renders 6HB compact and insensitive to ions, suggesting an interplay between electrostatic and hydrophobic forces in the channels. This system provides a platform for understanding the structure–function relationship of biological channels and designing rules for the shape control of DNA nanostructures in biomedical applications.     

A streamlined high throughput screening method for the Mycobacterium neoaurum mutants with expected yield of biotransformation derivatives from sterols

Mycobacterium neoaurum is ideal strain for bioconversion of sterol into steroid drugs. 96-well plate high throughput screen was validated to be able to discriminate the mimic mixtures of 4-androstene-3,17-dione (AD), androsta-1,4-diene-3,17-dione (ADD) and bisnoraldehyde (BA) optimized by uniform design, which is more rapid and higher throughput than the HPLC-based method.     

Ni/γ-Al2O3催化剂上萘加氢生成十氢萘的催化反应研究

采用Ni/Al₂O₃催化剂,在高压固定床反应器中考察了反应温度、压力、空速和氢油体积比比等因素对萘饱和加氢反应行为的影响,尤其是反应条件对反式十氢萘和顺式十氢萘选择性的影响。研究表明,反式十氢萘和顺式十氢萘的选择性与反应操作条件密切相关;反式十氢萘与顺式十氢萘的比例随着氢油比和温度的升高而增加,而随着压力和空速的增加而减小。在反应温度260-290℃、反应压力为5-7 MPa、空速为1-1.5 h^-1及氢油体积比大于250时,十氢萘的选择性最高可达99%以上,萘的转化率接近100%,产物中反式和顺式十氢萘的比例最高,可达4.0左右。对Ni/γ-Al₂O₃催化剂稳定性进行了考察,初步发现催化活性组分的烧结或流失是催化剂失活和影响产物中反式十氢萘和顺式十氢萘比例的主要原因。     

Using Natural Cinchona Alkaloids to Promote the Enantioselective Addition of Dialkylzinc to N－Diphenylphosphinylimines

Cinchona alkaloids are utilized as chiral ligands to promote the enantioselective addition of dialkylzinc to N-diphenyiphosphinylirnlnes affording enantiomerically enriched N-diphenyiphosphinylamines in up to 91% ee.     

木瓜蛋白酶催化的不对称杂环酮 Aldol反应研究

采用木瓜蛋白酶多功能性催化不对称杂环酮与芳香醛之间的Aldol反应。通过对溶剂、含水量、投料比、酶载量以及反应温度等条件的筛选,发现木瓜蛋白酶在该反应体系中展示了较好的催化活性和底物适应性。在最佳条件下,获得了最高37%的产率和78%的ee值。本文报道的木瓜蛋白酶在有机溶剂中具有类似天然醛缩酶的催化功能。     

Sensitive and selective electrochemical detection of artemisinin based on its reaction with p-aminophenylboronic acid

The electrochemical detection of artemisinin generally requires high oxidation potential or the use of complex electrode modification. We find that artemisinin can react with p-aminophenylboronic acid to produce easily electrochemically detectable aminophenol for the first time. By making use of the new reaction, we report an alternative method to detect artemisinin through the determination of p-aminophenol. The calibration curve for the determination of artemisinin is linear in the range of 2 μmol L⁻¹ to 200 μmol L⁻¹ with the detection limit of 0.8 μmol L⁻¹, which is more sensitive than other reported electrochemical methods. The relative standard deviation is 4.83% for the determination of 10 μM artemisinin. Because the oxidation potential of p-aminophenol is around 0 V, the present method is high selective. When 40 μM, 90 μM and 140 μM of artemisinin were spiked to compound naphthoquine phosphate tablet samples, the recoveries are 107.6%, 105.4% and 101.7%, respectively. This detection strategy is attractive for the detection of artemisinin and its derivatives. The finding that artemisinin can react with aromatic boronic acid has the potential to be exploited for the development of other sensors, such as fluorescence artemisinin sensors.     

Simulation of EOM-based frequency-chirped laser slowing of MgF radicals

Here we propose a scheme to slow MgF molecules by using EOM-based frequency-chirped radiation pressure slowing. The scheme well addresses the need for a rapid chirp rate while light molecules are being laser slowed, whose scattering rate and recoil velocity are large. Two EOMs are used to compensate the rapidly changing Doppler shifts arised from the movement of molecules, and to cover the hyperfine energy structure of MgF, respectively. Based the scattering rate maps calculated from an optical Bloch equation model, individual molecule trajectories are simulated by using a semi-classical three-dimensional Monte Carlo approach. We show how the modulation configuration of EOM and the magnetic field influence the slowing results. The study shows that a cryogenic buffer gas-cooled MgF beam source is possible to be slowed down with a number of ～ 1.4 × 10⁶–10⁷, and the final forward speed peaks at ～ 10 m/s near the capture velocity of a molecular MOT.     

Improving the device performances of two-dimensional semiconducting transition metal dichalcogenides: Three strategies

Two-dimensional (2D) semiconductors are emerging as promising candidates for the next-generation nanoelectronics. As a type of unique channel materials, 2D semiconducting transition metal dichalcogenides (TMDCs), such as MoS₂ and WS₂, exhibit great potential for the state-of-the-art field-effect transistors owing to their atomically thin thicknesses, dangling-band free surfaces, and abundant band structures. Even so, the device performances of 2D semiconducting TMDCs are still failing to reach the theoretical values so far, which is attributed to the intrinsic defects, excessive doping, and daunting contacts between electrodes and channels. In this article, we review the up-to-date three strategies for improving the device performances of 2D semiconducting TMDCs: (i) the controllable synthesis of wafer-scale 2D semiconducting TMDCs single crystals to reduce the evolution of grain boundaries, (ii) the ingenious doping of 2D semiconducting TMDCs to modulate the band structures and suppress the impurity scatterings, and (iii) the optimization design of interfacial contacts between electrodes and channels to reduce the Schottky barrier heights and contact resistances. In the end, the challenges regarding the improvement of device performances of 2D semiconducting TMDCs are highlighted, and the further research directions are also proposed. We believe that this review is comprehensive and insightful for downscaling the electronic devices and extending the Moore’s law.