Mechanical properties of porous titanium compacts prepared by powder sintering

Porous Ti compacts for biomedical applications are successfully fabricated in the porosity range from 5.0 to 37.1 vol% by controlling sintering conditions and Ti powder sizes. Young’s modulus and bending strength at the porosity of around 30 vol% are found to be similar to those of human cortical bone.     

Activity measurement of gallium in the B2 phase of the CoGa–Sb system by the EMF method with zirconia-based solid electrolyte

Gallium activity in the B2 phase regions of both binary Co–Ga and ternary Co–Ga–Sb systems was measured by EMF method with stabilized zirconia solid electrolyte The temperature range was 1073–1273 K and Sb concentrations were 1, 2 and 3 mol fractions. Ga activity at 1173 and 1273 K increases sharply in Ga rich region and the addition of Sb to the CoGa phase increases Ga activity. Activity change corresponds to the lattice parameter change with Sb addition to the CoGa phase.     

Dynamically Programmed Switchable DNA Hydrogels Based on a DNA Circuit Mechanism

Biological stimuli‐responsive DNA hydrogels have attracted much attention in the field of medical engineering owing to their unique phase transitions from gel to sol through cleavage of DNA cross‐linking points in response to specific biomolecular inputs. In this paper, a new class of biological stimuli‐responsive DNA hydrogels with a dynamically programmed DNA system that relies on a DNA circuit system through cascading toehold‐mediated DNA displacement reactions is constructed, allowing the catalytic cleavage of cross‐linking points and main chains in response to an appropriate DNA input. The dynamically programmed DNA hydrogels exhibit a significant sharp phase transition from gel to sol in comparison to another DNA hydrogel showing noncatalytic cleavage of cross‐linking points due to synchronization of the catalytic cleavage of cross‐linking points and the main chains. Further, the sol–gel phase transitions of the DNA hydrogels in response to the DNA input are easily tunable by changing the cross‐linking density. Additionally, with a structure‐switching aptamer, DNA hydrogels encapsulating PEGylated gold nanoparticles can be used as enzyme‐free signal amplifiers for the colorimetric detection of adenosine 5′‐triphosphate (ATP); this detection system provides simplicity and higher sensitivity (limit of detection: 5.6 × 10^?6 m at 30 min) compared to other DNA hydrogel‐based ATP detection systems.     

An accurate center frequency tuning scheme for 450-KHz CMOS Gm-C bandpass filters

This paper describes a center frequency tuning technique for a second intermediate-frequency (IF) bandpass filter. The utilization of the step signal response ensures the direct measurement of the center frequency. This tuning technique guarantees the accuracy of the design. A 450-kHz G_m-C bandpass filter tuned using this technique has been developed to integrate the IF module for personal digital cellular (PDC) handsets for use in 0.35-μm CMOS. The filter with the tuning scheme achieves a center frequency accuracy of ±0.5%     

Optimization of Digital Growth of Thick N-Polar InGaN by MOCVD

Smooth 200 nm thick N-polar InGaN films were grown by metal–organic chemical vapor deposition (MOCVD) on sapphire using a digital approach consisting of a constant In, Ga, and N precursor flow with pulsed injection of H2 into the N2 carrier gas. Using this growth scheme, the H2 injection time was altered and the effect on the morphology and indium incorporation in the films observed. The effect of periodic insertion of additional GaN inter-layers on the surface morphology of the InGaN layers was also studied.     

Laterally vibrating MEMS resonant vacuum sensor based on cavity-SOI process for evaluation of wide range of sealed cavity pressure

Microsystem Technologies - This paper reports a laterally vibrating MEMS resonant vacuum sensor which senses ambient pressure based on the squeeze-film damping effect. The single-anchored...     

X射线激光Nd，Dy,Er和Yb薄膜靶表面氧化过程的石英晶振方法研究

用电子束蒸发方法在抛光玻璃衬底上分别制备了X射线激光用的稀土元素Nd ,Dy ,Er和Yb薄膜靶。用石英晶片作为陪片 ,通过测量晶振频率的方法研究了薄膜靶在真空、干燥空气及潮湿空气等不同环境中不同阶段的氧化层增长过程。发现除Yb薄膜在淀积结束后的干燥空气和潮湿空气环境中的氧化过程遵循倒对数规律之外 ,其它所有的氧化过程均可用对数规律很好地进行拟合。淀积结束后充入大气时 ,薄膜表面的快速氧化过程仅为数分钟。在相同的环境中 ,Nd氧化速率最高 ,Er和Dy其次 ,Yb最低 ;在不同的环境中 ,Nd受环境湿度的影响最大 ,Er和Dy其次 ,Yb最低。     

ICP-MS法测定地电化学(泡塑)样品中痕量金

通过实验验证了在酸性介质存在条件下用ICP-MS法测定地电化学(泡塑)样品中痕量金的可行性,在稀释因子存在条件下得到了方法的检出限为3 ng、精密度为1.40％.同时,通过制备模拟负载不同金含量的泡塑样品,计算加入标准物质回收率为88.80％～107.37％;与GAAS法测定结果进行显著性检验发现两组数据之间无显著性差...     

Proposal of new iterative scheme in GMRES

In the paper, GMRES is applied to various large matrices appearing in 3D field analyses. By changing the condition of the matrices, effective preconditioning of the matrix is sought. Also studied is a relationship between the residual norm and the precision evaluated during GMRES. The paper shows that the residual norm, which is indirectly computed in GMRES and has so far been used as a measure of precision, cannot be used as an indicator of the solution's accuracy. After discussing deterioration of precision, GMRES(m1), which solves matrices with a modified iterative scheme, is proposed. It is to be confirmed that GMRES(m1) is faster and more accurate than any of GMRES and its modified version, GMRES(m). © 1998 Scripta Technica, Electr Eng Jpn, 123(4): 15–24, 1998