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.     

Analysis of the microstructure near the crack tip of ASME Gr.92 steel after creep crack growth

The microstructures near to and remote from the tip of a crack in ASME Gr.92 steel were investigated after creep crack growth at 873 and 898 K, focusing on the martensitic lath, the dislocation structure, and precipitates. After creep, the mean lath width near the crack tip was obviously larger than that of the virgin material, whereas the lath width remote from the crack tip was only slightly larger than that of the virgin material. The mean dislocation density near the crack tip markedly decreased after creep, whereas only a small change was observed in the dislocation density remote from the crack tip. The mean size of M₂₃C₆ particles near the crack tip after creep was larger than that of the virgin material, whereas their mean size remote from the crack tip was almost the same as that of the virgin material.     

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.     

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     

Diffraction of electromagnetic plane wave by an infinite slit in a screen with surface impedance

Diffraction of an electromagnetic plane wave by an infinite slit in a screen with surface impedance is solved analytically as a boundary value problem under the assumption that the plane of incidence is normal to the slit in a screen of zero thickness surrounded by a homogeneous medium. The field expressions and the transmission coefficient are derived asymptotically, and their numerical solutions are presented for a special case of perfect conducting screen.     

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.     

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.