Trihydroxy-2-thiaquinolizidine derivatives as a new class of bicyclic glycosidase inhibitors

Trihydroxy-2-thiaquinolizidines, a new class of bicyclic dideoxy-iminohexitol glycosidase inhibitor derivatives with nominally the d-gluco, l-ido, d-manno and l-gulo configurations were synthesized. X-ray analyses indicated that the preferred conformation for d-gluco and d-manno derivatives was a flat trans-fused system. Unlike deoxynojirimycin, the compound with d-gluco configuration was selective for α-glucosidases (yeast and rice) and showed no inhibitory activity towards β-glucosidase (almond), α-galactosidase (green coffee beans), α-galactosidase (E. coli) and α-mannosidase (jack bean), while the l-ido derivative was specific for β-glucosidase (almond).     

Improved results on the robustness of stochastic approximation algorithms

This paper is a continuation of the research carried out in [1]–[2], where the robustness analysis for stochastic approximation algorithms is given for two cases: 1. The regression function and the Liapunov function are not zero at the sought-forx ⁰; 2. lim sup _n a131_{n i=1} ⁿ _i+1 is not zero, where { _i } are the measurement errors and {a _n} are the weighting coefficients in the algorithm. Allowing these deviations from zero to occur simultaneously but to remain small, this paper shows that the estimation error is still small even for a class of measurement errors more general than that considered in [2].This project is supported by the National Natural Science Foundation of China.     

A near-infrared Fourier transform Raman spectroscopy of epidermal keratinocytes: changes in the protein-DNA structure following malignant transformation

We report here the use of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy to analyze normal human epidermal keratinocytes prior to and following malignant transformation. Our analysis indicates specific Raman spectral differences between immortalized (HPK1A) and malignant ras transformed (HPK1A-ras) cells. In addition, striking spectral differences are seen in the DNA isolated from these cells and particularly in the 843/810 cm(-1) ratio with values of 1.6 +/- 0.13 in HPK1A cells and 0.68 +/- 0.09 in HPK1A-ras cells (mean +/- S.D., n = 12, P < 0.001) indicating specific alterations in the backbone conformation markers following malignant transformation. Subsequently, we analysed the effect of a strong inhibitor of keratinocyte growth, the Vitamin D analog EB1089, on the Raman spectra of intact cells and on the 843/810 cm(-1) ratio in the DNA isolated from both cell lines. Specific changes were observed in intact cells in the 1300-750 cm(-1) region. Furthermore, the 843/810 cm(-1) ratio of isolated DNA from HPK1A cells was not affected by EB1089 but significantly increased in DNA isolated from HPK1A-ras cells so much that it became closer to the value observed for HPK1A cells (1.07 +/- 0.10). Our data suggest that Raman analysis of DNA and in particular the 843/810 cm(-1) ratio can provide useful indices of malignant transformation and efficacy of anticancer agents.     

基于System Generator的DBF的建模与仿真

简要介绍数字波束形成的基本原理,在此基础上,利用System Generator(SG)进行数字波束形成系统的建模和仿真,并给出仿真结果.     

Broadband high-efficiency circularly polarized active antenna and array for RF front-end application

This paper presents a broadband high-efficiency circularly polarized (CP) active integrated antenna, and a broadband CP active array at 2 GHz. To realize the broadband CP antenna, a circular patch is aperture coupled by crossed slots in the ground plane, which are fed by an L-shaped microstrip feed line below the ground. The antenna is designed to serve the functions of both a radiator and a harmonics-terminated load for class-E high-efficiency power-amplifier (PA) integration. The broadband CP active antenna is realized by directly integrating the broadband CP antenna with the class-E PA. It achieves a 9% bandwidth (1.84-2.01 GHz) for axial ratio (AR) below 3 dB, and a 12% bandwidth for power-added efficiency (PAE) over 60%. To form the broadband CP active array, four active antenna elements are sequentially rotated, and each element is directly integrated with broadband class-E PA. A low-cost printed-circuit-board technology is employed in fabrication and a pseudomorphic high electron-mobility transistor is used. A peak drain efficiency of 71.5% for the class-E amplifier is measured at 1.95 GHz. The active array achieves a peak-effective radiated power of 39.7 dBm, and PAE is over 50% within a 22.6% bandwidth (1.72-2.16 GHz). The AR is below 3 dB over a 27% bandwidth (1.72-2.26 GHz).     

集成抗ESD二极管的SOI LIGBT/LDMOS器件结构及其制作方法

为探索与国内VLSI制造工艺兼容的新型SOI LIGBT/LDMOS器件与PIC的设计理论和工艺实现方法,首次提出含有抗ESD二极管的集成SOI LIGBT/LDMOS器件截面结构和版图结构,并根据器件结构给出了阻性负载时器件的大信号等效电路.探讨了该结构器件的VLSI工艺实现方法,设计了工艺流程.讨论了设计抗ESD二极管相关参数所需考虑的主要因素,并给出了结构实现的工艺控制要求.     

微机电系统扭转微镜面驱动器的研制

提出了一种新颖的采用键合减薄工艺制作的微机电系统扭转微镜面驱动器,该种微镜面驱动器工艺制作简便可行.通过对研制的微镜面驱动器进行测试,该驱动器在18V驱动电压时可以达到0.3°的扭转角度,微镜面的频率响应时间小于1ms.同时该驱动器具有较大的微反射镜面,面积达到600μm×700μm,试验结果表明微镜面驱动器将可以应用于光通信领域.     

HBT matrix amplifier with gain-cell enhancing gain and bandwidth

A 2 /spl mu/m InGaP/GaAs heterojunction bipolar transistor (HBT) matrix amplifier with a new gain cell achieving 17.2 dB gain and 41 GHz bandwidth is reported. Using the gain-bandwidth products per transistor f/sub t/ and f/sub max/ as the figures of merit for measuring the effectiveness of amplifier design, it achieves 4.72 and 4.43, respectively, demonstrating among the best-reported bipolar broadband amplifiers     

Two-stage quasi-class-E power amplifier in GaN HEMT technology

This letter presents a two-stage quasi-class-E monolithic microwave integrated circuit power amplifier at 2.0GHz, which is based on field-plated GaN high electron mobility transistor technology. It consists of a driver stage and a power stage. The circuit schematic is described. The amplifier achieves an output power of 37.5dBm into a 50-/spl Omega/ load, a power added efficiency (PAE) of 50%, and a gain of 18.2dB. A power density of 5.6W/mm is achieved.     

光网络的保护策略

对光网络中的保护方法进行分类描述,结合当前的研究状况,对光网络保护算法的研究方向,提出相关见解.