IMPROVEMENT OF TYPE IV CRACKING RESISTANCE OF 9Cr HEAT RESISTING STEEL WELDMENT BY BORON ADDITION

Creep lives of high Cr ferritic heat resisting steel weldments decrease due to Type Ⅳ fracture, which occurs as a result of formation and growth of creep voids and cracks on grain boundaries in fine-grained heat affected zone (HAZ). Because boron is considered to suppress the coarsening of grain boundary precipitates and growth of creep voids, we have investigated the effect of boron addition on the creep properties of 9Cr steel weldments. Four kinds of 9Cr3WSCoVNb steels with boron content varying from 4.7×10-5 to 1.8×10-4 and with nitrogen as low as 2.0×10-5 were prepared. The steel plates were welded by gas tungsten arc welding and crept at 923K. It was found that the microstructures of HAZ were quite different from those of conventional high Cr steels such as P91 and P92, namely the fine-grained HAZ did not exist in the present steel weldments. Boron addition also has the effect to suppress coarsening of grain boundary carbides in HAZ during creep. As a result of these phenomena, the welded join     

High tensile strength fiber of poly[(R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate] processed by two‐step drawing with intermediate annealing

High tensile strength fibers of poly[(R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate] [P(3HB‐co‐3HH)], a type of microbial polyesters, were processed by one‐step and two‐step cold‐drawn method with intermediate annealing. Thermal degradation behaviors were characterized by differential scanning calorimeter and gel permeation chromatography measurements. Thermal analyses were revealed that molecular weights decreased drastically within melting time at a few minute. One‐step cold‐drawn fiber with drawing ratio of 10 showed tensile strength of 281 MPa, while tensile strength of as‐spun fiber was 78 MPa. When two‐step drawing was applied for P(3HB‐co‐3HH) fibers, the tensile strength was led to 420 MPa. Furthermore, the optimization of intermediate annealing condition leads to enhance the tensile strength at 552 MPa of P(3HB‐co‐3HH) fiber. Wide‐angel X‐ray diffraction measurements of these fibers suggest that the fibers with high tensile strength include much amount of the planer‐zigzag conformation (β‐form) as molecular conformation together with 2₁ helix conformation (α‐form). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41258.     

结构性黄土湿陷性指标室内测定方法的探讨

对黄土湿陷性指标的室内测定，国内外都借助标准压密仪，采用单线法或双线法进行。由于多种原因，我国各部委编制的试验规程，对采用何种方法，意见尚未统一。本文首先从人工制备结构性黄土的试验成果出发，讨论了黄土的湿陷线问题，认为非饱和结构性黄土存在湿陷线，且该线与饱和结构性黄土的压密曲线重合。从而说明在此简单应力路径下，单线法和双线法是等价的。接着，从日本大阪海成粘土不同室内压密方法得出的试验结果出发，就天然结构黄土，探讨了常规标准压密试验方法的不足，提议采用等应变压密双线法，来测定结构性黄土的湿陷性指标，从而有利于实际工程应用。     

Synthesis of offset parabola with open-ended waveguides feed

The synthesis of an offset parabola with array feeds consisting of open-ended waveguides located around the focal point of the reflector is investigated. The approach is based on simulated annealing which has been applied to the analysis to two-dimensional phased arrays. Two cases of aperture distributions, uniform and Taylor with 30-dB sidelobe level, are discussed. Both results seem to be satisfactory     

An Automatic Guidance System of a Self-Controlled Vehicle

An automatically guided vehicle, traveling without fixed guide ways, has been developed. In this paper, the construction of the vehicle, the control algorithm, and its general performance are described.     

The IGF-I receptor in mitogenesis and transformation of mouse embryo cells: role of receptor number

The type 1 receptor for insulin-like growth factors (IGF-IR) plays an important role in the growth and transformation of several types of cells. We have investigated the role of IGF-IR number in IGF-I-mediated mitogenesis and transformation of mouse embryo fibroblasts. We have used R- cells (3T3-like cells originating from mouse embryos with a targeted disruption of the IGF-IR genes) transfected with a plasmid expressing the human IGF-IR cDNA to generate clones with receptor numbers ranging from zero to 10(6) receptors per cell. In this model, between 15,000 and 22,000 receptors per cell are sufficient to render mouse embryo cells competent to grow in serum-free medium supplemented solely with IGF-I. For growth in soft agar, 30,000 receptors per cell seem to be the minimum requirement. These experiments indicate that a small increment in the number of receptors per cell, well within the physiological range, can modulate the mitogenic and transforming activities of the IGF-IR in 3T3-like cells.     

New tetrapolar circuit method using magnetic field for measurementof local impedance change in biological substances

A new tetrapolar circuit method using a magnetic field is proposed to measure the local electric impedance change in living tissue. Based on this method, we designed an apparatus which can detect impedance changes in closely-situated two parts of living tissue, simultaneously and independently. Using this apparatus, we showed the effectiveness of the proposed method by an in vitro experiment and by an in vivo measurement of pulsatile waveforms in the forearm arteries. The detection sensitivity for a local impedance change was confirmed to be higher than that of the conventional tetrapolar method. Pulsatile impedance waveforms measured in the radial and the ulnar parts of the forearm were consistent with those estimated from the anatomical structure.     

Impact of corticotropin-releasing hormone on gastrointestinal motility and adrenocorticotropic hormone in normal controls and patients with irritable bowel syndrome

The present study adopted a prospective design to explore relationships among various types of social support and depression. Four types of social support, namely network support, instrumental enacted support, socio-emotional enacted support, and perceived support, were assessed in a sample of Chinese adolescents. Results revealed that perceived support was related to a reduction of subsequent depression for both male and female adolescents. In addition, instrumental enacted support was a significant predictor of subsequent depression for male adolescents, whereas socioemotional enacted support was a significant predictor of subsequent depression for female adolescents. Functional differences in the types of social support for Chinese male and female adolescents, as well as implications for clinical intervention, are discussed.     

Scattering of electromagnetic pulse waves by conducting wedge in uniaxially anisotropic plasma

Asymptotic expansion for the transient response of radiation fields due to electric dipole located above the conducting wedge with an arbitrary angle embedded in a simple plasma is derived by using the saddle point method of integration. The transient time, which is defined as the time required to reach steady state, is discussed for various kinds of wedge angles and plasma frequencies.