A new method for generating a hollow Gaussian beam

Hollow Gaussian beam (HGB) was introduced 10 years ago (Cai et al. in Opt Lett 28:1084, 2003). In this paper, we introduce a new method for generating a HGB through transforming a Laguerre–Gaussian beam with radial index 0 and azimuthal index l into a HGB with mode n = l/2. Furthermore, we report experimental generation of a HGB based on the proposed method, and we carry out experimental study of the focusing properties of the generated HGB. Our experimental results agree well with the theoretical predictions.     

Direct-writing organic three-dimensional nanofibrous structure

Direct-writing technology based on Near-Field Electrospinning (NFES) was used to fabricate an organic three-dimensional nanofibrous circle on the patterned silicon substrate. In NFES, straight jet without splitting and chaotic motion was utilized to direct-write orderly nanofiber. When the collector movement speed was lower than electrospinning rate, the relaxed nanofiber would be lead into the pendulum motion by the electrical field force and Coulomb repulsion force from the residual charges on the collector. When the relative air humidity is lower than 35%, individual nanofiber with larger elastic resistance would reveal a good self-assembly performance. Owing to the guidance of the electric field force at the edge of the micro-pattern, a nanofiber was deposited layer by layer to format a 3D nanofibrous circle on the top surface of the micro-pattern. The dimension scale of 3D nanofibrous circle was smaller than 30 μm. With the help of a microscope, a 3D nanofibrous circle can be deposited precisely on the strip micro-pattern with width of 4 μm. Furthermore, a 3D nanofibrous circle in different shapes can be obtained by using special micro-patterns. This organic three-dimensional nanofibrous circle has created a new aspect for the fabrication of organic micro/nanosystems.     

Quasi-static analysis of multicrossover structures in grounded two-layer dielectric media

The capacitive coupling effects of multi-crossover structures in grounded two-layer dielectric media are investigated by a set of generalized quasi-static formulations. The moment method is employed to solve the set of generalized integral equations for the charge densities. Both the distributed capacitances and the lumped excess capacitances are computed.     

Full-wave analyses of H-meshed-strip line by an FDTD networking approach

A finite-difference time-domain (FDTD) networking approach is applied to the full-wave analysis of the transmission properties of H-meshed-strip line. The network formulation incorporated with the FDTD method leads to a large saving in computation time and computer memory.This work was supported by the National Natural Science Fundation of China.     

L(+)-乳酸提取纯化新工艺

发酵制备L(+)-乳酸过程中,发酵醪液分离提纯的时间和成本占到整个生产过程的一半以上,大大限制了乳酸生产工业的发展.针对此种情况,需探索出低成本高效率的分离提纯精制L(+)-乳酸的新工艺,以提高产品收率和纯度.本工艺过程:发酵醪液微波灭菌、高速离心、活性碳除色、膜过滤除蛋白质、柱分离、柱精制、真空浓缩得成品.生产过程不产生硫酸钙废弃物,减少对环境的污染,提取率由原来50%提高到71%以上.     

用双计算全息图检测凹非球面

为实现对凹非球面的高精度检测,提出并设计了一种二元纯相位型双计算全息图.设计的双计算全息图由主全息和对准全息两部分组成,分别用于检测非球面和精确定位主全息.介绍了双计算全息图的工作原理及其设计方法,并给出了一个检测Φ140、F/2抛物面反射镜的双计算全息图设计实例,实验得到的均方根(RMS)误差为0.062λ.通过分析对准全息的误差,推导出主全息的条纹位置畸变误差,最后计算出其综合误差为0.06A.为验证实验结果的可靠性,将其与平面镜自准直检测结果(ERMS=0.062A)比较,结果二者吻合良好.     

A novel photoelectric MOSFET with AC output under constant illumination

Traditional photoelectric devices can generate only DC electric signals under constant illumination. In this work, a novel photoelectric metal-oxide-semiconductor field-effect transistor (MOSFET) with AC output under constant illumination is introduced, in which the channel current is modulated by the gate voltage. This virtue can greatly simplify the signal processing circuitry. This photoelectric MOSFET has been successfully fabricated using a standard 0.8 micron MOSFET process.     

Identification of Key Reversible Intermediates in Self‐Reconstructed Nickel‐Based Hybrid Electrocatalysts for Oxygen Evolution

The oxygen evolution reaction (OER) has been explored extensively for reliable hydrogen supply to boost the energy conversion efficiency. The superior OER performance of newly developed non‐noble metal electrocatalysts has concealed the identification of the real active species of the catalysts. Now, the critical active phase in nickel‐based materials (represented by NiNPS) was directly identified by observing the dynamic surface reconstruction during the harsh OER process via combining in situ Raman tracking and ex situ microscopy and spectroscopy analyses. The irreversible phase transformation from NiNPS to α‐Ni(OH)₂ and reversible phase transition between α‐Ni(OH)₂ and γ‐NiOOH prior to OER demonstrate γ‐NiOOH as the key active species for OER. The hybrid catalyst exhibits 48‐fold enhanced catalytic current at 300 mV and remarkably reduced Tafel slope to 46 mV dec^?1, indicating the greatly accelerated catalytic kinetics after surface evolution.