Raman Microprobe Evaluation of Bridging Stresses in Highly Anisotropic Silicon Nitride

The microscopic bridging stress distribution developed behind the crack tip of a highly anisotropic silicon nitride has been measured along the crack profile using Raman microprobe spectroscopy with a micrometer spatial resolution. The near-tip rising R -curve behavior and the crack-opening displacement (COD) profile of the material were also determined and discussed in comparison with the Raman microstress data. A comparison with the fracture behavior of a previously investigated silicon nitride material with a three-dimensional random microstructure is also proposed. According to this set of micro/macroscopic fracture characterizations, a self-consistent view of toughening behavior in silicon nitride ceramics is obtained, and the role on toughness of anisotropically oriented acicular grains clarified. In agreement with previous studies, it is confirmed that crack-face bridging is the most effective mechanism for toughening silicon nitride ceramics.     

Uni-directional heat flux through the horizontal fluid layer with sinusoidal wall temperature at the top or bottom boundaries

Infinite horizontal fluid layer is considered between the top and bottom walls. Either top or bottom wall temperature is sinusoidally oscillated in terms of the constant average temperature in an opposing horizontal wall. This is the system with no temperature difference between the top and bottom walls in time-averaged sense, as studied by Kalabin et al. for a square channel. The fluid is Newtonian and Boussinesq approximation is made. The fluid layer of height 1 versus the horizontal width 1 or 4 is adopted and numerical computations are carried out for Pr = 1. The time-averaged Nusselt numbers computed both at top and bottom walls give the upward time-averaged heat flux without depending on the temperature oscillation either at the upper or lower walls. This is because the time-dependent convection plumes occur at the almost largest temperature of the bottom wall in comparison to the top wall. The time-averaged heat flux is always positive, i.e., upward, even if the time-averaged temperature difference is zero between the top and bottom walls.     

Nd–Fe–B thick films prepared at the high deposition rate of 90 µm/h

After a postannealing process, the magnetic properties of pulsed laser deposition (PLD)‐made Nd–Fe–B film magnets prepared at the deposition rate of 20–90 µm/h showed constant values, and the average values of H_c, B_r and (BH)_max were 1050 kA/m, 0.6 T, and 60 kJ/m³, respectively. The obtained results were comparable to those previously reported. In conclusion, it was found that a maximum deposition rate of 90 µm/h could be achieved without deterioration of magnetic and mechanical properties. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

An RTN Variation Tolerant SRAM Screening Test Design with Gaussian Mixtures Approximations of Long-Tail Distributions

This paper points out that the ordinary screening-test design (STD) will be no longer available when once the random telegraph noise (RTN) could not be ignored any more, resulting from a significantly increasing of the time-dependent modulation of the overall voltage-margin variations (OVMV). Since the major RTN effect on the OVMV modulation comes up after the screening, the actual precision of the STD must rely entirely upon the estimation accuracy of the RTN effect. The proposed STD is based on the developed statistical convolution model capable of fulfilling the following requirements: (1) precisely approximating the non Gaussian tail distribution of the RTN by simple Gaussian mixtures model (GMM), (2) accurately convoluting the RTN tail with the distribution of the Gaussian random dopant fluctuation (RDF). The proposed concepts are 1) sequentially and adaptively segmentation of the long tailed distributions such that the log-likelihood of the GMM in each segment is maximized. It has been verified that the proposed method can reduce the error of the fail-bit predictions by 3-orders of magnitude at the interest raw score where the fail probability pdf = 10^?12 which corresponds to a 99.9 % yield for 1Gbit chips.     

Joint Transmit Power Control and Rate Adaptation for Wireless LANs

Wireless local area networks (WLANs) are widely deployed recently. But many basic service sets (BSSs) nearby have to share a common channel due to the limitation in the spectrum resource. To get higher throughput with newly deployed access points (APs), it is necessary to improve spatial reuse of the channels by transmit power control (TPC). The achievable throughput, however, heavily depends on other factors such as rate adaptation (RA). Moreover, TPC without careful design may lead to asymmetric links and degrade fairness. In this paper, we jointly design TPC and RA to further improve total throughput of WLANs, and suggest (i) choosing power for each BSS by maximizing throughput which takes tradeoff between transmit rate and spatial reuse of channels, and, (ii) avoiding potential asymmetric links by explicit coordination among APs: each BSS uses almost the same power as its co-channel neighbors while BSSs far from each other may use different power levels as required. Extensive simulation evaluations confirm that the proposed scheme can greatly improve total throughput of dense WLANs, meanwhile fairness is retained.     

Quantitative analysis of quercetin using Raman spectroscopy

Raman spectroscopy was used for the quantitative analysis of quercetin. Raman spectra were measured with an Ar ion laser at 488 nm. A 20× objective lens was used for focusing the laser beam on the sample. The back scattering light was passed into the monochrometer and detected with a CCD detector. The Raman band of a solvent (ethanol and methanol) was used as the internal standard to remove the effect of factors such as laser power and other instrumental effect. The band ratio between the Raman intensity of the sample and that of the solvent had good linearity with the analyte concentration. The equations of the calibration curve were y = 9.005x with an R² of 0.9998 and y = 11.50x with R² of 0.9999 in ethanol and methanol, respectively. The limit of detection (LOD) was 5 × 10⁻⁵ mol/L. The quantity of quercetin extracted from onion peels was determined by Raman spectroscopy. Masses in quercetins of 73 mg/100 g and 70 mg/100 g were extracted from dried onion peels by using hot ethanol and hot methanol for three hours. These values are in good agreement with results obtained by HPLC and UV–vis spectroscopy.     

不同长度粒料对玻璃纤维增强聚丙烯复合材料力学性能的影响

对采用玻璃纤维形成的不同长度粒料(3.00 mm的短纤维粒料1种,7.00、11.00、15.00 mm的长纤维粒料3种)所制备的4种玻璃纤维增强聚丙烯复合材料进行拉伸、弯曲、冲击试验,测量注塑成型后残留的玻璃纤维长度,采用X-ray CT扫描法观察复合材料内部的纤维排列,探讨不同长度玻璃纤维对复合材料力学性能的影响。结果表明:注塑成型后玻璃纤维断裂严重,4种粒料的玻璃纤维长度均下降50%以上。随着玻璃纤维的原始长度从1.50 mm增加到15.00 mm,残留纤维长度从0.68 mm增加到4.18 mm。在残留纤维长度从0.68 mm增加到3.02 mm范围内,复合材料的拉伸强度和弯曲强度明显提高;在残留纤维长度从3.02mm增加到4.18 mm范围内,复合材料的拉伸强度和弯曲强度保持稳定。复合材料的冲击强度随着玻璃纤维的原始长度增加而增加。以短纤维增强粒料制得的复合材料,虽然玻璃纤维的原始长度非常短,但纤维排列接近长度方向;以长纤维增强粒料制得的复合材料,其芯层有宽阔的纤维排列杂乱区,纤维取向趋向无序状态,且该现象随着玻璃纤维的原始长度增加而加剧,部分纤维发生相互缠绕。     

Towards Personalized Medicine Mediated by in Vitro Virus-Based Interactome Approaches

We have developed a simple in vitro virus (IVV) selection system based on cell-free co-translation, using a highly stable and efficient mRNA display method. The IVV system is applicable to the high-throughput and comprehensive analysis of proteins and protein–ligand interactions. Huge amounts of genomic sequence data have been generated over the last decade. The accumulated genetic alterations and the interactome networks identified within cells represent a universal feature of a disease, and knowledge of these aspects can help to determine the optimal therapy for the disease. The concept of the “integrome” has been developed as a means of integrating large amounts of data. We have developed an interactome analysis method aimed at providing individually-targeted health care. We also consider future prospects for this system.     

Electro-oxidation of hydrolysed poly-oxymethylene-dimethylether on PtRu supported catalysts

Poly-oxymethylene-dimethylether (CH₃-O-(CH₂-O)_n-CH₃ (n = 3), abbreviated as POMM₃), which has no toxicity and a very low vapour pressure, unlike methanol, was investigated as a possible liquid fuel for a direct oxidation-type fuel cell. The electrocatalytic activity towards the oxidation of methanol, formaldehyde and a fully hydrolysed form of POMM₃ in 0.1 mol dm⁻³ HClO₄ solution was examined from 30 °C to 90 °C by using a channel flow cell system at three different types of PtRu catalysts, dispersed on high surface area supports, i.e., carbon black, antimony-doped tin oxide (Sb-SnO₂), and the latter mixed with a certain fraction of acetylene black (AB) to improve the electronic conductivity. The PtRu/Sb-SnO₂ + AB catalyst exhibited the best electrocatalytic activity and thermal stability towards the fully hydrolysed POMM₃ and formaldehyde oxidations, for which the mass activity was about ten times higher than that for methanol.     

Compressive Behavior During the Transition of Strain Rates

The application of a strain-rate-dependent model, for example, an isotache model, is very useful and highly effective for predicting the settlement due to consolidation, including secondary consolidation. In the isotache model, compression curves are not only determined by pressure, but also by strain rate. The validity of this model has been experimentally confirmed by many researchers using different types of oedometer tests, such as constant rate of strain (CRS) tests, incremental loading (IL) tests, etc. However, considerable scatter has been observed in the test results, which show the effects of the strain rate, and questions arise as to whether such scatter is caused by the heterogeneity of the soil samples or by the incompletion of the model. To avoid the heterogeneity of the tested samples, special CRS tests, in which the strain rate is not kept constant but is varied during the tests, were carried out on intact and reconstituted Osaka clay samples. The effects of the strain rate on the compressive behavior of these clays were carefully evaluated in terms of visco-plastic strain, assuming that the total strain consists of visco-plastic strain and elastic strain. It was confirmed that the stress and the visco-plastic strain relation of clay samples strongly depends on the visco-plastic strain rate. However, the effects of the strain rate, under a given constant visco-plastic strain rate, do not become constant when the visco-plastic strain rate becomes very small. The reason is assumed to be due to the development of structures under a constant small visco-plastic strain rate. The development of structures may restrict the applicability of the isotache model to the compressive behavior of clay.