873 research outputs found

    Topological Matrix Model

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    Starting from the primal principle based on the noncommutative nature of (9+1)-dimensional spacetime, we construct a topologically twisted version of the supersymmetric reduced model with a certain modification. Our formulation automatically provides extra 1+1 dimensions, thereby the dimensions of spacetime are promoted to 10+2. With a suitable gauge choice, we can reduce the model with (10+2)-dimensional spacetime to the one with (9+1)-dimensions and thus we regard this gauge as the light-cone gauge. It is suggested that the model so obtained would describe the light-cone F-theory. From this viewpoint we argue the relation of the reduced model to the matrix model of M-theory and the SL(2,Z) symmetry of type IIB string theory. We also discuss the general covariance of the matrix model in a broken phase, and make some comments on the background independence.Comment: 18 pages, LaTeX, no figures, minor corrections and modifications, references adde

    Development of fully-automated synthesis systems

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    This paper describes the development of fully-automated synthesis systems for preparing and isolating various kinds of pharmaceutical compounds. The systems are versatile, and are able to perform most of the chemical reactions currently used in organic chemistry, with the exception of hydrogenation which requires high pressure. An additional benefit is the very user-friendly software

    Computer-assisted automated synthesis. III. Synthesis of substituted N-(carboxyalkyl) amino-acid tert-butyl ester derivatives

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    A versatile automated synthesis apparatus, equipped with a chemical artificial intelligence, was developed to prepare and isolate a wide variety of compounds. The apparatus was to the synthesis of substituted N-(carboxyalkyl)amino-acids. The apparatus [1,2] is composed of units for performing various tasks,for example reagent supply, reaction, purification and separation, each linked to a control system. All synthetic processes, including washing and drying of the apparatus after each synthetic run, were automatically performed from the mixing of the reactants to the isolation of the products as powders or crystals. The reaction of an amino-acid tertbutyl ester acetic acid salt with a 2-keto acid sodium salt produces an unstable intermediate, Schiff base, which is reduced with sodum cyanoborohydride to give a substituted N-(carboxyalkyl)aminoacid tert-butyl ester sodium salt. The equilibrium and the consecutive reactions were controlled by adding sodium cyanoborohydride using the artificial intelligence software, which contained novel kinetic equations [3] and substituent effects [4]

    Particle size and surface texturing effects on friction of magnetorheological fluids

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    MR fluids are produced by dispersing micron-sized ferrimagnetic particles in oil. Generally, the presence of foreign particles in a lubricant affects the sliding behavior of the lubricated surface. Accordingly, the dispersed particles in MR fluids should significantly affect the lubrication properties of the fluids. In this study, we investigated the lubrication properties of MR fluids through sliding tests and in situ observations, while focusing on the behavior of the dispersed particles. MR fluids containing dispersed particles of various diameters were tested. The results of the sliding tests suggested that the MR fluid with the smallest particles exhibited the best lubrication characteristics. Surface observations showed the presence of grooves on the lubricated surfaces after wear. It is assumed that the grooves are formed by the abrasive action of the dispersed particles and that they affect the behavior of the particles. In situ observations proved that, in the case of flat surfaces, the dispersed particles remained stationary during sliding. On the other hand, in case of grooved surfaces, they moved along the grooves. Given these results, it can be surmised that the grooves on the worn surface changed the behavior of the particles and improved the lubricity of MR fluids

    Evaluation of carbon dioxide absorption by amine based absorbent

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    AbstractToshiba has developed amine based aqueous solution (Toshiba solvent 1, TS-1) that can significantly reduce CO2 regeneration energy compared with general 30 wt% monoethanolamine (MEA) aqueous solution and reported the results of the pilot plant of 10 t- CO2/day recovery from the flue gas of a coal- fired power plant. In order to reduce the CO2 regeneration energy further, we have developed new hindered amine based absorbent, Absorbent-A.In the present work, Absorbent-A was evaluated for CO2 absorption properties by laboratory scale apparatus. Absorbent-A was found to have the high CO2 absorption capacity and the low reaction heat. Furthermore, the CO2 regeneration energy of Absorbent-A was 45% less than that of general 30 wt% MEA aqueous solution.In future, we will additionally evaluate Absorbent-A in order to test in the pilot plant

    Effectiveness of Surface Texturing for Improving the Anti-seizure Property of Copper Alloy

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    AbstractIt is well known that lead-bronze is widely used in the automotive industry owing to the high anti-seizure property. However, because of toxicity of lead, the automotive industry demands a lead-free copper alloy from the viewpoint of environment. Lead- free copper alloy, which has the anti-seizure property as high as lead-bronze, has not been yet well exploited. For this reason, the objective of this study is to improve the anti-seizure property of lead-free copper alloy using a laser surface texturing (LST). In this study, a ring-on-ring sliding friction tester was used to assess the effectiveness of LST on the anti-seizure property of lead- free copper alloy. The upper specimens were made of FCD700, while the textured bottom specimens were made of PBC2 (lead- free copper alloy). A Daphne Hydraulic Fluid 32 (Idemitsu) paraffinic oil was used as a lubricant. The sliding friction test was conducted with a running-in period for 10min at a load of 50N. Afterwards, the load was increased incrementally from 50N to 1600N, while the friction coefficient was measured simultaneously. The friction test results showed that the textured specimens have a better anti-seizure property compared to the non-textured specimens. Based on the obtained experimental results, it was concluded that the arrangement and area ratio of dimples play an important role in improving the anti-seizure property

    Structural Study of SiO_x Amorphous Thin Films by the Grazing Incidence X-ray Scattering (GIXS) Method

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    Atomic structures of SiO_x amorphous thin films of 200 nm thick were analyzed by the grazing incident x-ray scattering (GIXS) method. The radial distribution functions (RDFs) were experimentally determined in two SiO_x amorphous thin films grown in the atmosphere with and without N_2 gas. The SiO_x amorphous film grown with N_2 gas forms the network structure consisting of SiO_4 tetrahedra which are connected each other by oxygen atoms at their vertices. This network structure is similar to the one observed in SiO_2 glass. On the other hand, in the SiO_x amorphous film grown without N_2 gas, the atomic distance of Si-O pairs is a few percent longer and the coordination number of O-O pairs is smaller than the other. This suggests that some of oxygen atoms in a SiO_4 tetrahedron are not connected to a next neighboring tetrahedron. Namely, some part of the network structure is disconnected in the SiO_x amorphous film grown without N_2 gas. Due to this imperfection of the network structure, it is expected that the SiO_x film grown without N_2 gas would be inferior to the other one grown with N_2 gas in some electrical properties as an insulator
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