Experimental study of drag-reduction mechanism for a dilute surfactant solution flow

The quantitative characteristics of vortex structures and turbulent events in turbulent channel flows with and without drag reduction were investigated experimentally. Drag reducing aqueous solutions of CTAC (CTAC – cetyltrimethyl ammonium chloride) with concentration of 25 ppm and 75 ppm at 30 °C were tested. Particle image velocimetry (PIV) was used to measure the instantaneous velocity field in the streamwise–wall-normal plane of the flow. Through visualizing the instantaneous vector fields, contour maps of the swirling strength and instantaneous value of uv (u and v are the streamwise and wall-normal velocity fluctuations, respectively), the characteristic angle of vortex packets was quantified. It was shown that the drag-reducing CTAC additive reduced both the strength and frequency of turbulent bursts near the wall, and the characteristics of vortex structures and bursts were not only dependent on drag-reduction level but also on concentration of additive. From the quantified parameters characterizing turbulent events in a wall-bounded turbulent flow, it was obtained that f_T was linearly proportional to the product of frequency and strength of turbulent events.     

PREPARATION OF MICROSPHERES WITH LIQUID CRYSTAL RESPONSES

We synthesized a ferroelectric liquid crystal monomer possessing both carboxyl p-benzolxy-benzoate and carboxyl (s)-(-)-2-methylbutyl ester in its side chain. The liquid crystal and styrene monomers were utilized to form matrices of microspheres prepared by the dispersion or suspension polymerization. In this study, we characterized in detail physicochemical properties, thermo-responses, or electro-optical responses in the microspheres. We demonstrated the following results: (1) the volume-averaged diameters of microspheres prepared by the dispersion or suspension polymerization were of 1.5 or 45 μm, respectively, (2) the microspheres prepared showed liquid crystal abilities at the prescribed temperature, (3) the phase transition temperatures toward the liquid crystal phase of the microspheres prepared by copolymerizing the liquid crystal and styrene monomers could be decreased with increasing styrene monomer concentrations, and (4) the microspheres obtained remarkably exhibited electro-optical responses at the appointed voltage.     

应用现代控制理论的丰用5档自动变速器

我们已经开发一种精确的和高性能的轿车用5档自动变速器（A350E）。开发这种变速器的目的在于改善在低和中等速度范围内的加速和平稳加速。具有简单传动系的5档自动变速器已经完全应用了工业最现代控制理论辅助换档技术。     

Heat transfer characteristics of a rotary regenerative combustion system (RRX)

With a view to saving fuel, the use of regenerative burners as a heating source has been spreading in the field of industrial furnaces. By combining a burner with a regenerative air preheater, a second generation regenerative burner—the Rotary Regenerative Combustion System (RRX)—has been developed, which makes for lower emission of air pollutants and compactness, in addition to fuel savings. In this paper, heat transfer characteristics of RRX were deduced theoretically based on the heat transfer theory of a regenerative air preheater and investigated experimentally using two test rigs. A commercially operating fired heater was revamped in the summer of 1994 to install three sets of RRXs, and it has been successfully operated for one year. As a result, it was determined that the heat transfer rate in RRX can be predicted to within ±10%, by considering not only convective but also radiative heat transfer. Furthermore, it was confirmed both theoretically and experimentally that fuel efficiency exceeding 90% was stably attained in a commercial fired heater. Around 60 ppm of NOx emission (as dry, 6% O₂) was also measured, although the preheated air temperature was calculated to be as high as 930 K. © 1999 Scripta Technica, Heat Trans Jpn Res, 27(8): 584–596, 1998     

Heat transfer characteristics and particle behavior around circular tubes immersed in fluidized beds

In this study, the particle velocity, particle volume fraction (attenuation of transmission light), and heat transfer coefficient were simultaneously measured for a horizontal tube bundle immersed in a fluidized bed of 0.42 mm diameter glass beads. To improve the accuracy of the particle velocity measurements, an optical fiber probe composed of a combination of transmission and reflection types was designed. The particle velocities were calculated by using the cross-correlation method and the particle passing-time method, respectively. It was shown by comparison of particle velocities obtained by the two methods that the particle passing-time method gives more stable results. The particle velocities at the bottom and at the side of the tube were relatively large and appeared to have periodicity while those near the top of the tube were low. This particle contacting feature can be used to explain the heat transfer characteristics. © 1998 Scripta Technica. Heat Trans Jpn Res, 26(5): 306–318, 1997     

Frictional property of Ti-B-N coating with preferred grain orientations deposited by arc ion plating under dry condition

It was shown in the previous paper that the low coefficients of friction of TiN coatings with (111) preferred grain orientation were measured under dry condition. In this paper, the new Ti-B-N coatings with (111) preferred grain orientation were developed for the industrial application. The coefficients of friction of the Ti-B-N coatings against steel materials were measured by ball-on-disc friction tester. As a result, it was found that the Ti-B-N coatings were able to maintain the low coefficients of friction over long sliding distance under severe sliding condition in comparison with the TiN coatings. It is understood that the Ti-B-N coatings have the possibility of being applied to the sliding parts of industrial machines under dry condition.     

Influence of properties of gas diffusion layers on the performance of polymer electrolyte-based unitized reversible fuel cells

Polymer electrolyte-based unitized reversible fuel cells (URFCs) combine the functionality of a fuel cell and an electrolyzer in a single device. In a URFC, titanium (Ti)-felt is used as a gas diffusion layer (GDL) of the oxygen electrode, whereas typical carbon paper is used as a GDL of the hydrogen electrode. Different samples of Ti-felt with different structural properties (porosity and fiber diameter) and PTFE content were prepared for use as GDLs of the oxygen electrode, and the relation between the properties of the GDL and the fuel cell performance was examined for both fuel cell and electrolysis operation modes. Experimental results showed that the cell with a Ti-felt GDL of 80 μm fiber diameter had the highest round-trip efficiency due to excellent fuel cell operation under relatively high-humidity conditions despite degradation in performance in the electrolysis mode.     

Structure-Based Design,Synthesis, and Biological Evaluation of Imidazo[4,5-b]pyridin-2-one-Based p38 MAP Kinase Inhibitors: Part 1

We identified a lead series of p38 mitogen-activated protein kinase inhibitors using a structure-based design strategy from high-throughput screening of hit compound 1 . X-ray crystallography of 1 with the kinase showed an infrequent flip of the peptide bond between Met109 and Gly110, which was considered to lead to high kinase selectivity. Our structure-based design strategy was to conduct scaffold transformation of 1 with maintenance of hydrogen bond interactions with the flipped hinge backbone of the enzyme. In accordance with this strategy, we focused on scaffold transformation to identify imidazo[4,5-b]pyridin-2-one derivatives as potent inhibitors of the p38 MAP kinase. Of the compounds evaluated, 21 was found to be a potent inhibitor of the p38 MAP kinase, lipopolysaccharide-induced tumor necrosis factor-α (TNF-α) production in human monocytic leukemia cells, and TNF-α-induced production of interleukin-8 in human whole blood cells. Herein we describe the discovery of potent and orally bioavailable imidazo[4,5-b]pyridin-2-one-based p38 MAP kinase inhibitors that suppressed cytokine production in a human whole blood cell-based assay.     

Synthesis of hollow silica microparticles from bacterial templates

Hollow inorganic particles have attracted great interest because of their unique physicochemical properties. In this study, hollow silica microparticles were prepared using a rod-shaped gram-negative bacterium, Escherichia coli (KP7600), as a biological template. Silica nanoparticles were generated in addition to coated biological templates when the reaction rate was increased, so control of reaction rate is important for coating silica smoothly onto the bacterial surface. Silica coating was also carried out using the fixed cells (with and without internal water) using glutaraldehyde as templates. When the fixed cells without internal water were used as templates, no rod-shaped particles were observed after calcination of the synthesized particles. By contrast, silica hollow particles were formed using the fixed cells with internal water as templates. This means that the internal water inside biological cells acts as an initiator for hydrolysis of tetraethyl orthosilicate (TEOS) and results in the formation of smooth silica shell surface and indicates that the use of dry cultured bacteria templates is not required. Thus, there is a significant benefit in using gram-negative bacteria as templates for producing hollow silica microparticles, compared with the method using dried gram-positive bacteria templates.