Oxidation behavior of sus430 stainless steel in moist atmospheres at 873 k

The oxidation behavior of SUS430 stainless steel was studied in moist atmospheres at 873 K. The mass gain during oxidation was measured by using a thermobalance. An abnormal rapid oxidation occurred after an incubation period which increased with increasing oxygen partial pressure. The product on the surface was identified as -Fe₂O₃ of whisker-like morphology by X-ray diffraction and scanning electron microscopy. The abnormal oxidation was not observed under high-oxygen partial pressures. The results of the experiments conducted in various atmospheres were analyzed and are discussed.     

Fundamental investigation of subsurface damage in single crystalline silicon caused by diamond machining

Single crystalline silicon was plunge-cut using diamond tools at a low speed. Cross-sectional transmission electron microscopy and laser micro-Raman spectroscopy were used to examine the subsurface structure of the machined sample. The results showed that the thickness of the machining-induced amorphous layer strongly depends on the tool rake angle and depth of cut, and fluctuates synchronously with surface waviness. Dislocation activity was observed below the amorphous layers in all instances, where the dislocation density depended on the cutting conditions. The machining pressure was estimated from the micro-cutting forces, and a subsurface damage model was proposed by considering the phase transformation and dislocation behavior of silicon under high-pressure conditions.     

Superplasticity of Hot Isostatically Pressed Hydroxyapatite

Dense and translucent hydroxyapatite polycrystals (Ca₁₀(PO₄)₆(OH)₂ with a grain size of 0.64 μMm) were obtained by hot isostatic pressing at 203 MPa and 1000°C for 2 h in argon. The material exhibited superplastic elongation (>150%) in a tension test at temperatures from 1000° to 1100°C and at strain rates from 7.2×10⁻⁵ to 3.6 × 10⁻⁴ s⁻¹. Extensive strain hardening was observed. The stress exponent of the yield stress was larger than 3.     

An optical projection system with mirrors for laparoscopy

We propose an optical projection system aimed at improving laparoscopic surgery based on three-dimensional (3D) measurement that gives an effective information for robotic-assisted surgery and computer-aided surgery. Laparoscopic surgery, which involves the creation of small ports through the patient’s body for the laparoscope and surgical instruments, such as clamp, is minimally invasive and has generated a growing interest. There are techniques using the stereo laparoscope to obtain depth information. Active sensing when structured light is added to the laparoscope can reconstruct a 3D shape. However, active sensing that requires projection devices for the structured light leads to an increase in size. Large-sized projection and sensing systems affect surgical procedures. The size of the system is also larger than the size of port for the laparoscope. To remove the obstacle for the surgery, it is important to design downsized systems. For active sensing with the structured light, a small-size projection system is required to use a small port for the laparoscope. Therefore, we built the optical projection system toward downsizing the device to stereoscopic vision of the laparoscope using mirrors, and we show a new shape reconstruction method from its active sensing. Our Experimental results demonstrate the effectiveness of this proposed system and method.     

二足步行机器人三维动步行的双脚支撑期的理论解析及仿真

本文以１０自由度二足步行机器人三维动步行的实现为目的，根据动力矩和静力矩的概念，运用Ｓ和Ｆ非分离的三维力学分析方法，对于双脚支持期的二足步行运动，进行了理论解析和步行仿真，证明了该方法的有效性。     

Analyses of diffusion-related phenomena in steel process

In steel production processes, there are various diffusion-related phenomena, and these are controlled to obtain the required steel quality. In the refining process, the slag-metal reaction that is controlled by the diffusion of various reactants and products in boundary layers in both the slag and metal side along the slag-metal interface is analyzed by a coupled reaction model. Solidification microsegregation is controlled by the solute diffusion in the liquid and solid phases, and various analytical microsegregation models have been proposed. The tertiary precipitation of nonmetallic inclusions is also affected by solute diffusion in the solid phase and is analyzed by a coupled precipitation model, the modified solidification segregation model. The formation of a carbon (C)-rich band structure along the centerline of steel plates and weld cracking are also prevented by regulating the diffusion of C by accelerated cooling and by encouraging hydrogen to diffuse out by preheating the weld part, respectively. A key element of intragranular ferrite precipitation for ferrite grain refinement is the formation of manganese (Mn)-depleted zone by slow Mn diffusion around a precipitate.     

Hydroxyl radical oxidation destabilizes subfragment-1 but not the rod of myosin in chicken myofibrils

The thermal denaturation process of myosin in oxidized chicken myofibrils was investigated. Exposures of myofibrils to hydroxyl radical-generation systems (HRGS) resulted in an enhanced susceptibility of myosin to thermal inactivation of Ca-ATPase and a loss of salt solubility. The chymotryptic production of subfragment-1 (S-1) from myosin in oxidized myofibrils decreased more rapidly than that in un-oxidized myofibrils upon heating, which paralleled the Ca-ATPase decay. However, the heat-induced decrease in chymotryptic production of rod from myosin was not affected by the HRGS treatment. The results suggested that free radical oxidation promoted thermal destabilization of myosin in the S-1 portion instead of the rod portion. The altered myosin denaturation pattern due to hydroxyl radical oxidation was likely a cause for functionality changes in oxidatively stressed myofibrillar proteins in meat processing.     

Scanning electron microscopic observation of immunohistochemically specified stromal cells following the NaOH maceration method

The present study introduces a method combining immunohistochemistry and a chemical digestion technique applied to scanning electron microscopy (SEM) observation of chemically characterized stromal cells in the myenteric layer of the monkey small intestine. The whole-mount preparation containing the myenteric layer was treated immunohistochemically using small colloidal gold and silver enhancements for detecting a certain type of stromal cell, followed by an alkali maceration method to remove extracellular matrices covering the immunohistochemically stained cells. This method permitted direct SEM observation of the stained stromal cells. Secondary and backscatter electron images clearly visualized the ultrastructure of the immunohistochemically-stained cells and the spatial distribution of the reaction products, respectively. It is suggested that the present method is useful for demonstrating the three-dimensional organization of the chemically specified stromal cells.     

Optical loss change caused by hydraulic pressure in multimode optical fibres

The optical loss change caused by hydraulic pressure in a multimode plastic-coated fibre with a buffer layer was examined. The relationship between loss change and fibre dimensions was found. A large-outer-diameter fibre exhibits a small change in the optical loss caused by hydraulic pressure.     

Isolation and characterization of a high-acetate-producing sake yeast Saccharomyces cerevisiae

The result of sensory evaluation of sake showed that acetic acid imparted desirable acidity when the proportion of acetic acid to lactic acid was about 1/3, even if the concentration of acetic acid was 0.75 g/l. Glycerol balanced the acidity and brought about a harmony between sweetness and acidity in sake. A high-acetate producing sake yeast (MHA-3) was isolated from mutants having low NADH dehydrogenase (NDE) activity. MHA-3 produced 15 times more acetate and 5 times more lactate than the parental strain Kyokai no. 901 (K-901) in a small-scale sake brewing test using 10 kg of rice. In addition, the concentrations of glycerol in sake brewed with MHA-3 were approximately 1.5-fold higher than in that brewed with K-901. The proportion of acetic acid to lactic acid was about 1/3 in sake fermented with MHA-3 and it exhibited a good balance between sweetness and acidity. The activities of glycerol-3-phosphate dehydrogenase (GPD) and aldehyde dehydrogenase (ALD) in MHA-3 were 1.4-fold and 3.1-fold, respectively, higher than those in K-901 while the activity of NDE was 40% that of K-901. MHA-3 accumulated higher amounts of acetate and glycerol than K-901 in static YNB10 medium. The concentrations of acetic acid produced, depending on the quantity of yeast cells added, increased in conjunction with increases in glycerol produced. We suggest that NDE might be linked with GPD and that the nde mutants, which can be used in sake brewing, produced higher amounts of acetate and glycerol.