An evaluation method of radial accuracy for hydrostatic air spindles considering radial movement of the rotating center

In this paper, we observed radial movement of the rotating center of a hydrostatic air spindle and have proposed an evaluation method of radial accuracy including radial movement of the rotating center. Our results are summarized as follows: (1) porous type spindles experienced limited radial motion during single revolutions. However, excessive rotating center movement was noted in comparison with inherent compensation restrictor types. (2) In the horizontal position, radial movement of the rotating center of an air spindle was excessive in comparison with the vertical position. (3) Repeatability of radial movement of the rotating center was within 0.1 μm. (4) As for radial movement of the rotating center, radial accuracy of the air spindle was significantly higher than the motion of one revolution.     

Tribological Behavior of Rice Bran Ceramics in a Vacuum Environment

ABSTRACT

In this study, we investigated the friction and wear of rice bran (RB) ceramics—hard porous carbon materials made from rice bran—in a vacuum environment. Sliding friction tests for RB ceramic pin–RB ceramic disk contact were performed using a pin-on-disk-type friction tester installed in a vacuum chamber. The ambient pressure was controlled at 0.02, 0.6, 30, and 10⁵ Pa (i.e., atmospheric pressure). The normal load was 0.49 or 2.94 N, the sliding velocity was 0.01 or 0.1 m/s, and the number of friction cycles was 50,000. The friction coefficient tended to decrease with decreasing ambient pressure for all combinations of normal load and sliding velocity; by contrast, the specific wear rate of the RB ceramic pin and disk specimens tended to increase with decreasing ambient pressure. The friction coefficient exhibited a low value of 0.05 or less at 0.02 Pa. The results suggested that the reduced surface roughness and graphitization of the sliding surface of the RB ceramic pin and disk due to induced friction, as well as the increased ratio between the partial pressure of water vapor and the ambient pressure, are related to the reduction in the friction of RB ceramic–RB ceramic dry sliding contact under vacuum conditions.     

Direct measurement of energetic electron flow in Q-shu University experiment with steady-state spherical tokamak

In magnetized plasmas, the presence of a significant number of energetic electrons has been observed but quantitative characteristics of these electrons are proving difficult to investigate. A Langmuir probe offers a means to provide quantitative measurement of these energetic electrons that takes into account electron emissions (secondary electron emission and electron reflection) from the probe tips and sheath expansion around the probe tips caused by a considerable negative potential. In this paper, these effects are experimentally confirmed and an analytical means to measure energetic electron characteristics are proposed. An analysis of plasmas produced by a high frequency wave is then applied leading to the successful detection of an asymmetric flow of energetic electrons. The estimated electron temperature and current density were approximately 4-5 keV and 2-3 kA/m(2).     

Wave-dispersive x-ray spectrometer for simultaneous acquisition of several characteristic lines based on strongly and accurately shaped Ge crystal

Si and Ge are widely used as analyzing crystals for x-rays. Drastic and accurate shaping of Si or Ge gives significant advance in the x-ray field, although covalently bonded Si or Ge crystals have long been believed to be not deformable to various shapes. Recently, we developed a deformation technique for obtaining strongly and accurately shaped Si or Ge wafers of high crystal quality, and the use of the deformed wafer made it possible to produce fine-focused x-rays. In the present study, we prepared a cylindrical Ge wafer with a radius of curvature of 50 mm, and acquired fluorescent x-rays simultaneously from four elements by combining the cylindrical Ge wafer with a position-sensitive detector. The energy resolution of the x-ray fluorescence spectrum was as good as that obtained using a flat single crystal, and its gain was over 100. The demonstration of the simultaneous acquisition of high-resolution x-ray fluorescence spectra indicated various possibilities of x-ray spectrometry, such as one-shot x-ray spectroscopy and highly efficient wave-dispersive x-ray spectrometers.     

Internal stress of epoxy resin modified with acrylic polymers having crosslinks produced byin situ UV radiation polymerization

In order to reduce the internal stress of cured epoxy resin generated by shrinkage in the cooling process from cure temperature to room temperature, two kinds of acrylic polymers were introduced byin situ UV radiation polymerization prior to curing. Polybutyl acrylate (A) and butyl acrylate-monoethylene glycol dimethacrylate copolymer (molar ratio 955) (B) were used as the acrylic polymer. In the A-modified resin, a heterogeneous structure with spherical submicrometre domains were formed. In the B-modified resin, irregularly shaped submicrometre domains in which the microphase separation occurred were observed. The modulus of cured epoxy resin decreased as a result of the modifications, and was lower in the B-modified resin than in the A-modified resin. Therefore the internal stress decreased more effectively in the B-modified resin.     

Flexible electrophoretic display driven by solution‐processed organic thin‐film transistors

Abstract— An organic thin‐film‐transistor (OTFT) backplane has been fabricated by using a solution‐processed organic semiconductor (OSC) and organic insulators. The OSC, a peri‐xanthenoxanthene derivative, provides a mobility of 0.5 cm²/V‐sec. These organic materials enhance the mechanical flexibility of the backplane. The developed backplane successfully drives a 13.3‐in. flexible UXGA electrophoretic display that can operate when bent at a radius of 5 mm.     

Evaluation of biocompatibility of the surface of polyethylene films modified with various water soluble polymers using Ar plasma‐post polymerization technique

Surface modified polyethylene (g‐PE), PMPC‐g‐PE, PGEMA‐g‐PE, PNIPAAm‐g‐PE and PHPMA‐g‐PE films with the water soluble polymers such as poly[2‐(methacryloyloxy)ethyl phosphorylcholine] (PMPC), poly[2‐(glucosyloxy)ethyl methacrylate] (PGEMA), poly(N‐isopropylacrylamide) (PNIPAAm) and poly[N‐(2‐hydroxypropyl) methacrylamide] (PHPMA) were prepared by graft copolymerization using an Ar plasma‐post polymerization technique. The surface of the g‐PE films was characterized by means of X‐ray photoelectron spectroscopy and the grafting percentage of PMPC, PNIPAAm and PHPMA was found to be 5.31, 2.83, and 3.40% for the corresponding g‐PE film. Biocompatibility of the g‐PE films was evaluated by the adsorption of serum proteins and the Michaelis constant (K_m) for the enzymatic reaction of thrombin with synthetic substrate S‐2238 in the presence of g‐PE film. The biocompatibility of water soluble polymers such as PMPC, polyoxyethylene (POE), PGEMA, PNIPAAm and PHPMA was also evaluated by the same enzymatic reaction of thrombin with S‐2238 in their polymer solutions. The K_m values in the presence of water soluble polymers was found to decrease in the order PMPC > POE > PGEMA > PNIPAAm > PHPMA. As a conclusion, PMPC‐g‐PE film exhibited the most biocompatibility among g‐PE films because its surface adsorbed less protein than those of the untreated PE and other g‐PE films and it showed the largest K_m for the enzymatic reaction.     

Lactoferrin Ameliorates Dry Eye Disease Potentially through Enhancement of Short-Chain Fatty Acid Production by Gut Microbiota in Mice

Lactoferrin is a glycoprotein found at high concentrations within exocrine secretions, including tears. Low levels of lactoferrin have been implicated in the loss of tear secretion and ageing. Furthermore, lactoferrin possesses a range of functionalities, including anti-inflammatory properties and the ability to modulate the gut microbiota. Expanding evidence demonstrates a crucial role of the gut microbiota in immune regulation and development. The specific composition of bacterial species of the gut has a profound influence on local and systemic inflammation, leading to a protective capacity against a number of inflammatory diseases, potentially by the induction of regulatory immune cells. In this study, we demonstrated that oral administration of lactoferrin maintains tear secretion in a restraint and desiccating stress induced mouse model of dry eye disease. Furthermore, we revealed that lactoferrin induces the reduction of inflammatory cytokines, modulates gut microbiota, and induces short-chain fatty acid production. Whereas, the antibiotic vancomycin abrogates the effects of lactoferrin on dry eye disease and significantly reduces short-chain fatty acid concentrations. Therefore, this protective effect of LF against a mice model of DED may be explained by our observations of an altered gut microbiota and an enhanced production of immunomodulatory short-chain fatty acids.     

Measurement of flow velocity for hydrogen introduced into a wall‐stabilized argon arc

Small solid particles are usually used as tracers for the measurement of flow velocity of a fluid. In the case of a high‐temperature thermal plasma, sometimes it is difficult to use solid tracers due to the loss by vaporization caused by strong heat transfer from the plasma. If gaseous tracers could be used, it would compensate for the difficulty in using conventional solid particle tracers. To investigate the feasibility of gaseous tracers, hydrogen was used as a gaseous tracer for flow velocity measurement of a well‐stabilized argon arc plasma. Propagation of Hα line emission along the arc axis was observed by high speed photography using a CCD camera with bandpass filters. The propagation velocity was 30 to 100 m/s which was influenced by the flow rate of argon. The Peclét number was calculated for the experimental condition. The result shows that the effect of the diffusion on the mass transport is smaller than that of the flow. This means that the propagating velocity of the Hα line emission closely corresponds to the flow velocity of the argon arc plasma with the added hydrogen. The measured velocity and the estimated average flow velocity of argon arc plasma were in good agreement. The principle of the gaseous tracer was confirmed, although further work will be needed for practical use. © 2001 Scripta Technica, Electr Eng Jpn, 135(1): 15–23, 2001