Flow‐controlled thermosyphon using multi‐stacked radiator cores

We have been developing a more compact cooling unit compared with the conventional cooling aluminum fin and the heat pipe‐type cooling unit. The aim of this paper is to examine the cooling performance of the cooling unit using multi‐stacked radiator cores and a new flow controller. We propose a new simple structure for the refrigerant circulation flow using multi‐stacked radiator cores with holes at both ends. Further we clarified that the cooling performance is greatly improved by the new refrigerant flow controller if the cooling unit is inclined. © 2000 Scripta Technica, Heat Trans Asian Res, 29(8): 648–659, 2000     

Design of a small‐size interlocking system with high availability

An interlocking system consists of an interlocking logical unit and a power controlling unit. After this logical unit calculates the relationship among the train position, the rail shifting position, and the signal, it decides the aspect of the signal. The power controlling unit supplies electrical power to the switch motor and the signal light according to the decision of the logical unit. This paper proposes a small‐sized interlocking system which uses a triplex redundant off‐the‐shelf controller with fail‐safe checker as an interlocking logical unit. A majority voting circuit ensures the safety of parallel output from the interlocking logical unit. This circuit satisfies the condition of total self‐checking (of D.A. Anderson) and also the condition of high availability. In other words, no single fault ever leads to a hazardous state and this circuit ensures safety after single fault occurrence. © 1999 Scripta Technica, Electr Eng Jpn, 128(2): 63–73, 1999     

A reverse process of superheated steam drying from condensation to evaporation

To clarify the mechanism of heat and mass transfer in the early stages of superheated steam drying which accompanies condensation and evaporation, an experiment in which a water surface was used as the dried material was conducted under atmospheric pressure. Temperature profiles in both the gas phase and the liquid phase near the water surface and the liquid level were measured precisely. From the results, heat transfer rates at the water surface and the amount of steam condensed into water were determined; in addition, the relationship between these two was investigated both experimentally and theoretically. Furthermore, a characteristic curve of drying accompanying condensation and evaporation in the early stages of superheated steam drying was derived semiempirically. In this drying characteristic curve, there is a point at which neither condensation nor evaporation occurs. This is defined as the “reverse point.” Introduction of this reverse point and the time ratio for condensation and evaporation during the early stages of superheated steam drying are clarified. © 1999 Scripta Technica, Heat Trans Asian Res, 28(5): 352–366, 1999     

Fucoxanthin Prevents Pancreatic Tumorigenesis in C57BL/6J Mice That Received Allogenic and Orthotopic Transplants of Cancer Cells

Fucoxanthin (Fx) is a marine carotenoid with anti-inflammatory and anti-cancer properties in various animal models of carcinogenesis. However, there is currently no information on the effects of Fx in animal models of pancreatic cancer. We investigated the chemopreventive effects of Fx in C57BL/6J mice that received allogenic and orthotopic transplantations of cancer cells (KMPC44) derived from a pancreatic cancer murine model (Ptf1a^Cre/+; LSL-kras^G12D/+). Using microarray, immunofluorescence, western blot, and siRNA analyses, alterations in cancer-related genes and protein expression were evaluated in pancreatic tumors of Fx-administered mice. Fx administration prevented the adenocarcinoma (ADC) development of pancreatic and parietal peritoneum tissues in a pancreatic cancer murine model, but not the incidence of ADC. Gene and protein expressions showed that the suppression of chemokine (C-C motif) ligand 21 (CCL21)/chemokine receptor 7 (CCR7) axis, its downstream of Rho A, B- and T-lymphocyte attenuator (BTLA), N-cadherin, αSMA, pFAK(Tyr³⁹⁷), and pPaxillin(Tyr³¹) were significantly suppressed in the pancreatic tumors of mice treated with Fx. In addition, Ccr7 knockdown significantly attenuated the growth of KMPC44 cells. These results suggest that Fx is a promising candidate for pancreatic cancer chemoprevention that mediates the suppression of the CCL21/CCR7 axis, BTLA, tumor microenvironment, epithelial mesenchymal transition, and adhesion.     

VVVF on-line control of matrix converters

A matrix converter does not have any energy storage components, so it is smaller than a converter-inverter system with same KVA. Although a matrix converter requires 18 switching devices instead of 12, each device capacity is 0.383 times with a total capacity of 0.575 times that of the converter-inverter system. For the matrix converter, we proposed a firing sequence which eliminated voltage and current spikes in switching operations and a control method I which generated the output voltage of 0.866 times the supply voltage. Moreover, we proposed control method II which improved the waveform distortion of the input current and realized unity input power factor. In this paper, we propose a new VVVF gate circuit based on control method II for matrix converter, which can on-line control input current waveform and output voltage waveform to sinusoidal even if there is fluctuation, asymmetry, and/or harmonics in the supply voltage. We also confirm by experiments that the waveform distortion of the input current and the input power factor were greatly improved. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(2): 81–90, 1997     

Optimum design of a long-stroke thin linear DC motor

Computers have been more widely used in recent years. Researchers are now able to analyze a magnetic field using the finite element method. A motor can be designed more effectively and rationally. It is important to understand design space. Design space means the limit of the thrust or design variables within constraints. Within these limited dimensions, a linear dc motor (LDM) for a pen recorder is designed. This LDM is very thin with long strokes. It is described as follows: (1) the thickness of the permanent magnet and the length of the gap are selected as the design variables in the magnetic circuit of the LDM; (2) the effective magnetic flux density of LDMs using the 3-D finite element method is compared; (3) the design space of thin LDM with long strokes is clarified. The LDM measurement value (thrust constant) was increased at 0.60 N/A from the first LDM. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (4): 84–93, 1997     

Alcohol oxidase hybrid oligomers formed in vivo and in vitro

Cell‐free extract prepared from methanol‐grown cells of the methylotrophic yeast Pichia methanolica showed nine multiple alcohol oxidase (AOD) bands on active staining in native polyacrylamide gel electrophoresis. Their molecular basis was investigated and two AOD‐encoding genes, MOD1 and MOD2, were cloned from P. methanolica genome. When the two genes were expressed in a heterologous host, an alcohol oxidase‐depleted strain of Candida boidinii(aod1Δ strain), both MOD1 and MOD2 partially complemented growth defect of the host strain on methanol. While expression of either MOD1 or MOD2 in C. boidinii aod1Δ strain gave a single AOD band corresponding to the band with the largest and smallest mobility among the nine AOD bands, respectively, co‐expression of MOD1 and MOD2 resulted in multiple band formation. Mixed oligomerization of Mod1p and Mod2p in vitro also gave nine multiple bands. From these results, we concluded that the nine multiple forms of AOD observed on native–PAGE represent two homo‐octamers and seven hetero‐octamers of Mod1p and Mod2p. Using this zymogram analysis, we also found that Mod1p was preferably produced at low methanol concentrations in the media, while Mod2p was produced at higher methanol concentrations. This shows distinct regulatory features of the two AOD‐encoding genes in this methylotrophic yeast. Copyright © 1999 John Wiley & Sons, Ltd.     

Surface Engineering of Top7 to Facilitate Structure Determination

Top7 is a de novo designed protein whose amino acid sequence has no evolutional trace. Such a property makes Top7 a suitable scaffold for studying the pure nature of protein and protein engineering applications. To use Top7 as an engineering scaffold, we initially attempted structure determination and found that crystals of our construct, which lacked the terminal hexahistidine tag, showed weak diffraction in X-ray structure determination. Thus, we decided to introduce surface residue mutations to facilitate crystal structure determination. The resulting surface mutants, Top7sm1 and Top7sm2, crystallized easily and diffracted to the resolution around 1.7 Å. Despite the improved data, we could not finalize the structures due to high R values. Although we could not identify the origin of the high R values of the surface mutants, we found that all the structures shared common packing architecture with consecutive intermolecular β-sheet formation aligned in one direction. Thus, we mutated the intermolecular interface to disrupt the intermolecular β-sheet formation, expecting to form a new crystal packing. The resulting mutant, Top7sm2-I68R, formed new crystal packing interactions as intended and diffracted to the resolution of 1.4 Å. The surface mutations contributed to crystal packing and high resolution. We finalized the structure model with the R/R_free values of 0.20/0.24. Top7sm2-I68R can be a useful model protein due to its convenient structure determination.     

Effect of Crystal Grain Size and Thermal Stress on Martensitic Transformation of Phosphorus-Bearing Dicalcium Silicates

A series of P₂O₅-bearing Ca₂SiO₄ solid solutions, (Ca_{2- x /2}open square _{x /2})(Si_{1- x} P _x )O₄ with x = 0.02 and 0.06 lessthan equal to 0.11, was prepared. The alpha´_L <–> ß martensitic transformation temperatures were determined by high-temperature XRD for powder specimens with x = 0.02. With decreasing particle size, both M _s and M _f decreased, while both A _s and A _f were almost unchanged. Each transformation temperature was lower than that of pure Ca₂SiO₄. The phase composition at 25°C for the crystals with 0.075 lessthan equal to x lessthan equal to 0.10 was dependent not only on the x -value but also on the particle size and the intensity of the thermal stress upon quenching. The effect of the latter two was most clearly recognized in the phase composition of the crystals with x = 0.09. The phase composition was changed between the two extremes; one was composed of 8% alpha´_L-phase and 92%ß-phase and the other was 96% alpha´_L-phase and 4%ß-phase. For the crystals with 0.06 lessthan equal to x lessthan equal to 0.065 (ß-phase) and 0.105 lessthan equal to x lessthan equal to 0.11 (alpha´_L-phase), only the x -value governed the phase composition.     

Equivalent model of the side wall electrodynamic suspension system

The side wall electrodynamic suspension (EDS) system has the advantage of not requiring gap control, and the magnetic drag is smaller than for the repulsion arrangement. This levitation system is applied in the JR magnetically levitated (Maglev) transportation system. The experimental results in the Miyazaki test line seem to indicate that this system has large damping. However, calculations show that this system has little damping and the reason for large damping in the test line is not clear. Thus, running characteristics and improved design can be investigated using numerical analysis to improve riding comfort and reduce loss of the superconducting magnet. Since this is a non-linear system, complicated analysis is needed. Usually the running characteristics of this EDS system are given by a numerical analysis that combines electromagnetic phenomena with mechanical equations of motion. However, this method requires very large calculation times. Thus, a simpler suspension model for this EDS system is needed. This paper presents levitation and guidance characteristics of the system and develops an equivalent suspension system model from the electric circuit characteristics. The approximation is developed by a simple function of the velocity and position of the bogie. The dynamic movement of the bogie was calculated easily using this model, and the results correspond to the results given by the electric circuit model. © 1998 Scripta Technica, Electr Eng Jpn, 124(2): 63–73, 1998