Small blaze angle gratings with various surface treatments for use in the extreme ultraviolet

Three replica gratings were made from a single master; two were epoxy overcoated with different thicknesses of gold, and one was replicated directly in gold. Their performance in EUV light at grazing incidence angles was measured and compared.     

非饱和水力传导系数的简易实验室测量方法

本文描述一种采用常规的实验装置在短时间内测量土层非饱和水力传导率的简易方法,称为"向上入渗法".这一方法基于在控制压力的条件下测量土的吸水量,从而来估算土层在湿润状态下的水力传导系数.将其结果与恒定加水量法、小增量压力变化法、一步法以及杰克逊理论模型的计算结果进行了比较.采用向上入渗法与采用恒定加水量法的结果很接近,但稍大于一步法而小于杰克逊理论模型的结果.这种测定方法限定负压值约为一米.     

Least squares approach in measurement-dependent filtering for selective medical images

An image-processing method called measurement-dependent filtering has been introduced to improve the SNR (signal-to-noise ratio) of selective images produced by various medical imaging systems. The basic algorithm involves the combination of the low-frequency information of the selective image with the high-frequency information of a nonselective image. A spatially variant control function modulates the amount of high frequency to be added at each point. A least-mean-square (LMS) control function formed from two basis images, namely the high-passed versions of the nonselective image (M(b)) and the selective image (S(b)), is introduced. The original algorithm is now viewed as a two-stage filtering method, including the low-pass filtering noise reduction and least squares filtering for the edge restoration. An appropriate linear transformation is used to convert the original basis images M(b) and S(b) into a new pair with orthogonal noise. This allows the implementation of the LMS and control function with practically obtainable a priori knowledge.     

High-frequency differential piezoelectric photoacoustic investigation of ion-implanted (100) silicon wafers via laser beam position modulation

An exploratory application of position-modulation photoacoustic imaging of ion-implanted (100)-oriented Si wafers was undertaken to assess its potential as a diagnostic probe in semiconductor processing. Wafer scans were performed using acoustooptic modulation of a 1.06-mum Nd(3+):YAG laser beam up to 0.2 MHz with piezoelectric photoacoustic detection. Sensitivity ranges to ion-implanted parameters (ionic species and fluences) were studied and the capability of the technique to monitor processing-induced damage was established. Results indicate that position-modulated photoacoustic detection offers higher sensitivity than single-beam photothermal imaging and has distinct advantages over other analytical techniques.     

计算机模拟扫描电镜颗粒边缘粗糙度外貌特征

各种石英颗粒表面特征的发育与否,是任何扫描电镜分析重建地质环境的基础,对于在石英颗粒表面获得的许多可见特征来说,虽然已有许多"清单"(Krinsley和Donahue,1968:Cater,1984),但是,专门检测技术的有效性还是一个争论的问题.由这类分析获得的最为重要的物理参数之一是边缘磨蚀,因为圆度值是一种发现于石英砂颗粒的主要形态特征.例如,1984年Goudie和Bull发现两类非洲沉积物之间的主要差异是,在深度风化剖面中总体缺乏边缘磨蚀颗粒,并以此为基础建立了该研究区的斜坡     

Ergonomics in sickle operation

Sickle operation in harvesting has been analysed with reference to design features of nine different types of sickles, and field and laboratory based investigations on biomechanical stresses and physiological valuation on six farmers. It has been indicated that the blade geometry contributes significantly to human performance and there is ample scope for further design optimisation. The suggested modifications are: (i) sickle weight - 200 g; (ii) total length of sickle - 33 cm; (iii) handle length - 11 cm; (iv) handle diameter - 3 c cm; (v) radius of blade curvature - 15 cm; (vi) blade concavity - 5 cm; (vii) serrated sickle: tooth pitch - 0.20 cm and tooth angle - 60 degrees; (viii) ratio of the length of cutting surface to chord length - 1.20.     

Pressure-induced conversion of α-connectin to β-connectin

The mechanism of the pressure-induced tenderization of meat has not been fully established in spite of its beneficial effect. To detect the changes in the large structural proteins of the myofibrils induced by pressurization without heat treatment, high hydrostatic pressure (100-300 MPa) was applied to rabbit at-death skeletal muscle for 10 min at low temperature (0-2°C). Significant differences in the electrophoretic pattern of connectin (also called titin) in isolated myofibrils were observed between the control and pressurized muscle samples. The conversion of α-connectin (2800 kDa) to β-connectin (2100 kDa) was accelerated with increasing pressure applied to the muscle; also nebulin (800 kDa) was degraded by pressure treatment. From the results it is clear that the degradation of connectin is induced by pressurization alone without heat treatment. If the conversion of α-connectin to β-connectin during conditioning has some influence on meat tenderization, the pressure-induced conversion of α- to β-connectin is possibly one of the causes of pressure-induced tenderization of meat.