Microstructures and Vickers hardness of rapidly solidified Al-Cu alloys near the Al-Al2Cu equilibrium eutectic composition

Al-Cu alloys near the Al-Al₂Cu equilibrium eutectic composition were rapidly solidified by the single-roller method. Two-zone structures were observed in transverse sections of Al-24.8, 30.0, 32.7, 33.2, 37.0 and 40.3 mass % Cu alloy ribbons, which were interpreted on the basis of the difference in cooling rates and of the temperature gradients between the chilled and free-surface sides of the ribbons. Non-equilibrium eutectic structures, cellular and irregular lamellar, were seen at the chilled side because the alloy liquids were directionally solidified with coupled eutectic growth. The coupled zone of the Al-Cu alloy expanded over the composition range 24.8–40.3 mass % Cu by rapid solidification. Dendritic structures were formed at the unchilled side of Al-24.8, 30.0, 37.0 and 40.3 mass % Cu alloys. Vickers hardness values at the chilled side differed from those at the unchilled side due to the difference in the microstructure.     

TGF-alpha, EGF, and their cognate EGF receptor are co-expressed with desmin during embryonic, fetal, and neonatal myogenesis in mouse tongue development

The developing mouse tongue provides a model for discrete patterns of morphogenesis during short periods of embryonic development. Occipital somite-derived myogenic cells interact with cranial neural crest-derived ecto-mesenchymal cells to form the musculature of the tongue. The biochemical signals that control close range autocrine and/or paracrine signaling processes required to establish the fast-twitch complex tongue musculature are not known. The present study was designed to test the hypothesis that desmin, epidermal growth factor (EGF), and transforming growth factor-alpha (TGF alpha) and their cognate receptor, epidermal growth factor receptor (EGFr), are co-expressed during tongue myogenesis and define specific developmental stages of tongue muscle cell differentiation. To test this hypothesis, we performed studies to analyze the timing, position, and concentration of desmin, TGF alpha, EGF, and EGFr from embryonic day 9 (E9) through birth in Swiss Webster mouse tongue development. Desmin, TGF alpha, EGF, and EGFr co-localized to cells of myogenic lineage in the four occipital somites and subsequently in myoblasts and myotubes from E9 through E17. By newborn stage, desmin is localized to discrete regions in myofibers corresponding to Z-line delimiting sarcomeres, and A-band within sarcomeres; immunostaining for desmin, TGF alpha, and EGF persisted in differentiated myotubes and striated skeletal muscle. Desmin increased from 0.01% at E11 to 0.51% of the total protein by E17 and at birth. Concomitantly, the patterns and increases in TGF alpha, EGF, and EGFr showed significant increases during the same developmental period. The temporal and positional co-localization of TGF alpha, EGF, and EGFr support the hypothesis that autocrine and paracrine regulation of desmin by actions of growth factor ligand and receptor defines critical stages of tongue myogenesis.     

A design technique for a high-gain, 10-GHz class-bandwidth GaAsMESFET amplifier IC module

A design procedure is proposed for a high-gain and wideband IC module, using stability analysis and a unified design methodology for ICs and packages. A multichip structure is developed using stability analysis and the requirements for stable operation are determined for each IC chip, package, and interface condition between them. Furthermore, to reduce the parasitic influences, several improvements in the interface and package design are clarified, such as wideband matching and LC resonance damping. IC design using effective feedback techniques for enlarging the bandwidth are also presented. The ICs are fabricated using 0.2-μm GaAs MESFET IC technology. To verify the validity of these techniques, an equalizer IC module for 10-Gb/s optical communication systems was fabricated, achieving a gain of 36 dB and a bandwidth of 9 GHz     

A study on autobalancing of a casing oscillator using feedback control

The casing oscillator used for basic construction of buildings, factories, and bridges is a construction machine which rotates and rolls the casing to insert it into the ground. It is very important that the casing is retained at a perpendicular position to sea level regardless of the slope of ground. In this paper, we present a new casing oscillator that does need not to be level to the ground for the casing insertion to work. The kinematic analysis for work space of a casing oscillator is presented and carried out with autobalancing of the casing oscillator using feedback control.     

Extrusion and melt spinning characteristics of thermally degraded polypropylene

A basic study of the influence of thermal degradation of polypropylene on its extrudate swell and melt spinning characteristics is reported. The degradation reduces swell, changes the shape of the spinline diameter/velocity profile (i.e., the spinline apparent elongational viscosity function), and stabilizes the melt spinning process. The importance of molecular weight distribution narrowing during the degradation process is noted in these studies.     

Digital control of torch position and weld pool in MIG weldingusing image processing device

A digital computer control system for improving the stability of the torch position and weld pool shape in metal inert gas (MIG) welding is proposed. It is shown how the characteristic of the digital controller may be selected for yielding a desired transient behavior