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排序方式: 共有938条查询结果,搜索用时 31 毫秒
921.
Koyama D Ide T Friend JR Nakamura K Ueha S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(3):597-604
This paper presents a noncontact sliding table design and measurements of its performance via ultrasonic levitation. A slider placed atop two vibrating guide rails is levitated by an acoustic radiation force emitted from the rails. A flexural traveling wave propagating along the guide rails allows noncontact transportation of the slider. Permitting a transport mechanism that reduces abrasion and dust generation with an inexpensive and simple structure. The profile of the sliding table was designed using the finite-element analysis (FEA) for high levitation and transportation efficiency. The prototype sliding table was made of alumina ceramic (Al2O3) to increase machining accuracy and rigidity using a structure composed of a pair of guide rails with a triangular cross section and piezoelectric transducers. Two types of transducers were used: bolt-clamped Langevin transducers and bimorph transducers. A 40-mm long slider was designed to fit atop the two rail guides. Flexural standing waves and torsional standing waves were observed along the guide rails at resonance, and the levitation of the slider was obtained using the flexural mode even while the levitation distance was less than 10 microm. The levitation distance of the slider was measured while increasing the slider's weight. The levitation pressure, rigidity, and vertical displacement amplitude of the levitating slider thus were measured to be 6.7 kN/m2, 3.0 kN/microm/m2, and less than 1 microm, respectively. Noncontact transport of the slider was achieved using phased drive of the two transducers at either end of the vibrating guide rail. By controlling the phase difference, the slider transportation direction could be switched, and a maximum thrust of 13 mN was obtained. 相似文献
922.
Study on an activated carbon fiber–ethanol adsorption chiller: Part I – system description and modelling 总被引:2,自引:1,他引:1
B.B. Saha I.I. El-Sharkawy A. Chakraborty S. Koyama 《International Journal of Refrigeration》2007,30(1):86-95
This article presents the transient modelling for a two-bed, activated carbon fiber (ACF)–ethanol adsorption chiller. This innovative adsorption chiller employs pitch based ACF of type A-20 as adsorbent which is a fibrous adsorbent having the advantages of fast adsorption rate, high porosity and ease of handling when compared with granular adsorbents and powdered adsorbents. Ethanol is used as refrigerant as it has no harm to environment, it is a non-toxic substance, moreover, ethanol has comparatively higher vapor pressure even at low temperature. This innovative system utilizes effectively low-temperature waste heat sources of temperature between 60 and 95 °C along with a coolant at 30 °C. We have found that, regardless of the initial mass distribution, the ACF–ethanol adsorption chiller is able to achieve the same cyclic-steady-state within three cycles or 1890 s. 相似文献
923.
924.
Reconstruction of bone fenestration on mandiblar by the guided bone regeneration methods with beta-TCP/PLGC membranes 总被引:1,自引:0,他引:1
Koyama Y Kikuchi M Edamura K Nagaoka K Tanaka S Tanaka J Takakuda K 《Journal of nanoscience and nanotechnology》2007,7(3):859-861
Guided Bone Regeneration (GBR) is a method for bone tissue regeneration. In this method, membranes are used to cover bone defects and to block the invasion of the surrounding soft tissues. It would provide sufficient time for the osteogenic cells from bone marrow to proliferate and form new bony tissues. In spite of the potential usefulness of this method, no appropriate materials for the GBR membrane have been developed. Here we design the ideal mechanical properties of the GBR membranes and created novel materials, which is the composite of beta-tricalcium phosphate (beta-TCP) and block copolymer of L-lactide, glycolide, and epsilon-caplolactone (PLGC). In the animal experiments with the use of the GBR membranes for large bone defects, we observed significant enhancement in the bone regeneration after 12 weeks implantation and proved the effectiveness of the materials. 相似文献
925.
Chemical Identification of MHC-influenced Volatile Compounds in Mouse Urine. I: Quantitative Proportions of Major Chemosignals 总被引:2,自引:0,他引:2
Novotny MV Soini HA Koyama S Wiesler D Bruce KE Penn DJ 《Journal of chemical ecology》2007,33(2):417-434
The genes of the major histocompatibility complex (MHC) are highly polymorphic loci that encode cell surface proteins, class I and II molecules. They present peptide antigens to T cells and thereby control immunological self/nonself recognition. Increasing evidence indicates that MHC genes also influence odor and mating preferences; however, it is unclear how. Here we report the results of chemical analyses of male mouse urinary odors collected from a variety of mouse strains, including MHC-congenics, recombinants, mutants, and transgenics (i.e., beta2 microglobulin "knockouts," which lack class I expression, and transporters associated with antigen processing (TAP) knock-outs). After the identification of volatile odor components by gas chromatography/mass spectrometry, the odor profiles of urine samples were analyzed quantitatively by using stir bar sorptive extraction and gas chromatography/atomic emission detection. Results showed that MHC genes influenced the amounts of testosterone-mediated pheromones, sulfur-containing compounds, and several carbonyl metabolites. This is the first report to quantitatively link known mouse pheromones to classical, antigen-binding MHC loci. Surprisingly, these compounds were not influenced by TAP genes, even though these loci are MHC-linked and play a role in peptide presentation. Whereas identification of MHC-determined odorants does not reveal their metabolic origin, some constituents were also present in blood serum, and their levels were not altered by antibiotics. 相似文献
926.
Khairul HabibBidyut Baran Saha Anutosh ChakrabortyShigeru Koyama Kandadai Srinivasan 《International Journal of Refrigeration》2011,34(1):129-137
This paper presents the results of an investigation on the performance of combined adsorption refrigeration cycles. The novel combined cycle amalgamates the activated carbon (AC)-R507A as the bottoming cycle and AC-R134a cycle as the topping cycle and deliver refrigeration load at as low as −10 °C at the bottoming cycle. The cycle simulation is based on the experimentally confirmed adsorption isotherms, kinetics and isosteric heat of adsorption data for R134a and R507A on highly porous based activated carbon of type Maxsorb III. The optimum cooling capacity, coefficient of performance (COP) and chiller efficiency are calculated in terms of cycle time, switching time, regeneration and brine inlet temperatures. Results show that the combined adsorption cycles are feasible even when low-temperature heat source is available. 相似文献
927.
Takimoto T Suzuki K Arisaka H Murata T Ozaki H Koyama N 《Molecular nutrition & food research》2011,55(10):1561-1571
Scope: The objective of this study is to investigate a vascular effect of N‐(p‐coumaroyl)serotonin (CS) and N‐feruloylserotonin (FS), major antioxidative indolic polyphenols in safflower seeds with anti‐atherogenic properties, with emphasis on effects on vascular smooth muscle cells (VSMCs). Methods and results: Both CS and FS (each 10 to 100 μM) relaxed rat femoral arteries, which were pre‐contracted by 10?5 M phenylephrine or 50 mM KCl, independently of their endothelium. Both CS and FS also concentration‐dependently inhibited the increase of cytosolic free Ca2+ concentration ([Ca2+]i) that was induced by KCl or 5‐hydroxytryptamine in cultured rat VSMCs. Next, we examined the effects of CS and FS on platelet‐derived growth factor (PDGF)‐BB‐evoked proliferation and migration of the VSMCs. Both CS and FS inhibited PDGF‐BB‐evoked proliferation and migration of the VSMCs in a concentration‐dependent manner. They also inhibited PDGF‐BB‐induced phosphorylation of PDGF receptor β and ERK1/2, and Ca2+ release from sarcoplasmic reticulum in the VSMCs in a concentration‐dependent fashion. Conclusion: These results indicated a possible vascular effect of CS/FS to inhibit the activation of VSMCs by blocking the increase of [Ca2+]i and/or blocking PDGF signaling. These may explain a part of anti‐atherogenic mechanism that underlies their ability to improve vascular distensibility and to inhibit aortic hyperplasia. 相似文献
928.
Yuki Orikasa Daiko Takamatsu Kentaro Yamamoto Yukinori Koyama Shinichiro Mori Titus Masese Takuya Mori Taketoshi Minato Hajime Tanida Tomoya Uruga Zempachi Ogumi Yoshiharu Uchimoto 《Advanced Materials Interfaces》2014,1(9)
Surface coating on lithium‐ion battery cathodes improves their durability at high potentials, which is a well‐known practical application. However, the mechanism is still unclear because the coating influences the electrode/electrolyte interface at a few nanometer‐scale and direct observation of the interface under real operating conditions of a battery is challenging. This study reveals the mechanism of the surface coating effect on lithium‐ion battery cathodes by using in operando X‐ray absorption spectroscopy (XAS) on well‐defined MgO‐coated LiCoO2 thin‐film electrodes prepared via pulsed laser deposition. Total‐reflection in operando XAS measurements reveal that LiCoO2 forms a reductive phase at the interface between the uncoated‐LiCoO2 electrode and the electrolyte, while the MgO coating layer inhibits the redox process, leading to an improvement in the cycle performance of the battery. Depth‐resolved in operando XAS measurements indicate that a solid solution of the magnesium phase forms at the LiCoO2 surface upon MgO coating. Magnesium ions function as pillars to stabilize the layered structure at the interface between the LiCoO2 electrode and the electrolyte for delithiated states upon cycling at potentials. 相似文献
929.
Alteration of Wax Ester Content and Composition in Euglena gracilis with Gene Silencing of 3‐ketoacyl‐CoA Thiolase Isozymes 下载免费PDF全文
Masami Nakazawa Hiroko Andoh Keiichiro Koyama Yomi Watanabe Takeo Nakai Mitsuhiro Ueda Tatsuji Sakamoto Hiroshi Inui Yoshihisa Nakano Kazutaka Miyatake 《Lipids》2015,50(5):483-492
Euglena gracilis produces wax ester under hypoxic and anaerobic culture conditions with a net synthesis of ATP. In wax ester fermentation, fatty acids are synthesized by reversing beta‐oxidation in mitochondria. A major species of wax ester produced by E. gracilis is myristyl myristate (14:0‐14:0Alc). Because of its shorter carbon chain length with saturated compounds, biodiesel produced from E. gracilis wax ester may have good cold flow properties with high oxidative stability. We reasoned that a slight metabolic modification would enable E. gracilis to produce a biofuel of ideal composition. In order to produce wax ester with shorter acyl chain length, we focused on isozymes of the enzyme 3‐ketoacyl‐CoA thiolase (KAT), a condensing enzyme of the mitochondrial fatty acid synthesis pathway in E. gracilis. We performed a gene silencing study of KAT isozymes in E. gracilis. Six KAT isozymes were identified in the E. gracilis EST database, and silencing any three of them (EgKAT1‐3) altered the wax ester amount and composition. In particular, silencing EgKAT1 induced a significant compositional shift to shorter carbon chain lengths in wax ester. A model fuel mixture inferred from the composition of wax ester in EgKAT1‐silenced cells showed a significant decrease in melting point compared to that of the control cells. 相似文献
930.
Shin‐Ichiro Tanifuji Tsuyoshi Kikuchi Jun‐Ichi Takimoto Kiyohito Koyama 《Polymer Engineering and Science》2000,40(8):1878-1893
This paper focuses on the overall numerical simulation of the parison formation and inflation process of extrusion blow molding. The competing effects due to swell and drawdown in the parison formation process were analyzed by a Lagrangian Eulerian (LE) finite element method (FEM) using an automatic remeshing technique. The parison extruded through an annular die was modeled as an axisymmetric unsteady nonisothermal flow with free surfaces and its viscoelastic properties were described by a K‐BKZ integral constitutive equation. An unsteady die‐swell simulation was performed to predict the time course of the extrudate parison shape under the influence of gravity and the parison controller. In addition, an unsteady large deformation analysis of the parison inflation process was also carried out using a three‐dimensional membrane FEM for viscoelastic material. The inflation sequence for the parison molded into a complex‐shaped mold cavity was analyzed. The numerical results were verified using experimental data from each of the sub‐processes. The greatest advantage of the overall simulation is that the variation in the parison dimension caused by the swell and drawdown effect can be incorporated into the inflation analysis, and consequently, the accuracy of the numerical prediction can be enhanced. The overall simulation technique provides a rational means to assist the mold design and the determination of the optimal process conditions. 相似文献