Symmetry in electron diffractions from helical structures

In this work, we elucidate the regular rule of the symmetry in electron diffraction patterns from helical structures. It is affected by the value of the dominating Bessel function orders for the layer lines and relative orientation of the samples with respect to the electron beam. For Single-Walled Carbon nanotubes (SWCNTs), we use analytic analysis and computer simulations to demonstrate that the 2mm symmetry of the electron diffraction may break down not only from an achiral SWCNT, but also from a chiral SWCNT. Also, the simulation work for B-DNA is presented to corroborate the theoretical analysis.     

2π空间发光的理想点光源系统

为获得能在２π空间发光的理想点光源，本文提出了一种特殊光学系统，介绍了这种系统的工作原理、设计方法和设计结果。     

Multiple-input microcantilever sensors

A surface-micromachined micro-electro-mechanical-system (MEMS) process has been used to demonstrate multiple-input chemical sensing using selectively coated cantilever arrays. Cantilever motion due to absorption-induced stress was readout using a custom-designed, eight-channel integrated circuit. Combined hydrogen and mercury vapor detection was achieved with a palm-sized, self-powered module with spread-spectrum telemetry reporting.     

An optimal feedrate model and solution algorithm for a high-speed machine of small line blocks with look-ahead

In complex high-speed machining of consecutive small line blocks, the tool path segments can be so short that a machining center moving at a high feedrate cannot accelerate or decelerate fast enough to make direction changes accurately. Aiming at adjusting the feedrate automatically to achieve maximum productivity, this paper present a novel mathematical model considering the key and representative factors, and then based on it, propose an algorithm to seek the approximate optimal feedrate by evaluating the toolpath ahead. Simulation results demonstrate the machine using the proposed model and algorithm can go fast where possible and to slow down just enough where needed and the productivity can be improved dramatically.     

Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@PAM@NTA-Ni<Superscript>2+</Superscript> Magnetic Composite Nanoparticles for Highly Specific Separation of His-tagged Proteins

A facile approach has been developed to synthesize Fe₃O₄@PAM (polyacrylamide) nanoparticles (NPs) with carboxyl groups on the surfaces by copolymerization with acrylamide and acrylic acid in Fe₃O₄ NPs aqueous suspension. Nitrilotriacetic acid (NTA) was conjugated to the magnetic NPs via well-known carboniimide chemistry using EDC and NHS. The Ni²⁺ ions loaded on the surface of NPs provide abundant docking sites for immobilization of His-tagged green fluorescent proteins (His-tagged GFP). The high magnetic property of Fe₃O₄@PAM@NTA-Ni²⁺ allows an easy separation of the NPs from solution under an external magnetic field, with high His-tagged protein binding capacity (42 μg protein/mg of NPs). The NPs can be recycled for at least four times without significant loss of binding capacity to proteins. These materials show great potential to separate His-tagged protein with low-cost purification at industrial scale.     

林区环境因素与CORS测量精度的相关性分析

在林区环境下的碎部测量中存在一定的障碍物对CORS信号进行干扰,影响CORS信号的站间传播。为研究林区环境因素与CORS测量精度之间的关系,通过获取林区优势树种的叶面积指数(LAI)和CORS测量精度等要素,利用SPSS软件分析其相关性。结果表明：不同优势树种的LAI值与CORS测量精度秩相关系数r_s>0.8,在p<0.01下呈强相关性,树冠投影面积与CORS测量精度的秩相关系数r_s>0.5,在p<0.01下呈现中等相关,而树冠高度和地形与CORS测量精度未得出相关性。     

CCD传感器实时检测系统在微细电火花加工机床上校正法的研究

CCD(Charge-Couple Device)传感器实时检测系统是一套基于光电检测技术的质量监测仪器,可用于实时观测和测量被加工工件,特别适合安装应用于微细电火花加工机床.本文就该系统安装在电火花加工机床上后如何提高检测精度进行研究,提出了3种方法对该检测系统进行校正,如,整体校准常数、C值校正、D值校正.此后设计实验来检验校准后该系统的稳定性和精确度,从而验证了所提出的三步校正法的可靠性.     

智能卡话者确认系统的研究

介绍了一个将参考模板存放在智能卡上的与相关的话者确认系统及其工作原理、相关算法和参数设置。