Computer simulation of morphological changes of grain boundary precipitates growing by the ledge mechanism

A previously developed computer model was modified to simulate the growth of grain boundary precipitates which grow by the ledge mechanism. The ledges were assumed to be nucleated in the grain boundary region at constant, parabolically decreasing, and random rates and to grow under the control of volume diffusion of solute to or from the riser of ledges. At lower under coolings at which the motion of individual ledges is slow, late-nucleated ledges soon catch up with first-nucleated ones, and precipitates tend to extend along the grain boundary: the overall precipitate shape is essentially that of a grain boundary allotriomorph. At larger undercoolings, first-nucleated ledges move fast to form a protuberance similar to Widmanstätten sideplates, while late-nucleated ones stay near the grain boundary region. The transition of precipitate shape from one to the other occurs in a very narrow range of supersaturation. The results are compared with various characteristics of the growth of proeutectoid ferrite allotriomorphs and sideplates in Fe-C alloys documented in the literature.     

Photocatalytic Property and Electronic Structure of Lanthanide-based Oxysulfides

Lanthanide-based oxysulfides and sulfide, LnTaO_3.5S_0.5, Ln₁₀OS₁₄ (Ln = La, Pr, Nd, Sm) and La₄In₅S₁₃, were successively synthesized by sulfurization in a flowing H₂S. The sulfurization decreased the band-gap energies from >4 eV to <3eV, because of the formation of occupied S3p orbitals on the top of valence band. In accordance with the small band gap, the H₂ evolution from a 0.01 M Na₂S and 0.01 M Na₂SO₃ solution system was observed under irradiation of light up to >500 nm. The rate of H₂ evolution under light irradiation of >500 nm increased in the order of Ni/LaTaO_3.5S_0.5 < Ru/La₁₀OS₁₄ < Pt/La₄In₅S₁₃.     

Binary Adsorption Isotherms of Water and Ethyl Acetate Vapor for Materials Contained in a Box of a Tobacco Product

An experimental study has been carried out on the characteristics of binary adsorption isotherms of water and volatile flavor for typical materials used in a box of a tobacco product or cigarettes. Ethyl acetate chosen as a model for water-soluble volatile flavor. Binary adsorption isotherms for the tobacco, papers, filters, and activated carbons were measured with a flow-type multi-component adsorption system under the canstant conditions of temperature a t 303 K and vapor pressure of water a t 2.5 kPain the vapor pressure range of ethyl acetate from 0 to 4.2 kPa. A linear equation was applied to express the binary adsorption isotherms for the tobacco, papers and filters, while a Dubinin-Astakhov equation was applied for the activated carbons. The binary adsorption was characterized into three groups, depending on the selectivity as well as the mechanism of adsorption; i.e.(l) for tobacco and papers, water was adsorbed much greater rather than ethyl acetate, (2) for filters, ethyl acetate was adsorbed on the surface as great as water, (3) for activated carbons, ethyl acetate was adsorbed much greater onto their micropores rather than water. The results showed that ethyl     

Three-dimensional pin power reconstruction for the axially heterogeneous region in BWR

A three-dimensional pin power reconstruction method was proposed and verified by applying to the axially heterogeneous region problem of the BWR core calculation. Because the production assembly calculation has been carried out by two-dimensional deterministic calculation methods like current coupling collision probability or the method of characteristics, it has been difficult to predict the detailed three-dimensional heterogeneous pin power distribution of the axially heterogeneous region. Consequently, only radial intranodal homogeneous power distributions have been considered, and axial intranodal homogeneous power distributions have not been considered in the estimation of linear-heat-generation-ratio at common BWR core calculations.     

Studies on chitin 3—effect of coagulants and annealing on the preparation and the properties of chitin membrane

Chitin membrane was prepared by casting a N,N-dimethyl acetamide, N-methyl 2-pyrrolidone and lithium chloride (DMA-NMP-LiCl)solution of chitin and coagulating with several media. The effect of the coagulants on membrane formation was studied. 2-Propanol was found to be more favourable than methanol, ethanol, acetone and mixtures of 2-propanol and water. The membrane obtained in 2-propanol was subjected to annealing. Annealing made the membrane dense and strong. The tensile strength of the membrane annealed at 145°C for 2hr was about twice that of an unannealed membrane. The solute permeability of the annealed membranes was lower than that of the original one. These phenomena could be clearly interpreted in terms of crystallinity.     

OSP-P200最新开放式数控系统

上世纪90年代末，受到以国际互联网为代表的信息技术革命的影响，制造业为了构筑新的生产方法，开始引入各种信息技术工具。这是为了满足消费者品种多样化和个性化的需求，以大量生产为主的产品导向模式（Product Out）向多品种小批量的市场导向模式（Marketin）的变化为目的，充分利用信息技术和设计制造知识，更加快速和低价地向市场提供各种高附加价值产品。     

Copolymerization of methylmethacrylate on a ball-milled surface of coal at 77 K

The ball-milling of coal with methylmethacrylate monomer was carried out under vacuum at 77 K and at room temperature and in air. The e.s.r. and i.r. spectra of ball-milled material showed that a copolymer of coal and methylmethacrylate was formed on the surfaces of coal created by ball-mining. Oxygen is an inhibitor to this process.     

E.s.r. study of annealing and melting effects on the molecular motion of spin trapped chain-end radicals located on the polyethylene surface

E.s.r. spectra of chain-end spin labels on the surface of polyethylene powder were obtained for high and low density polyethylene samples at various stages of heat treatment process. The subsequent crystalline structures of the samples were examined with wide angle and small angle X-ray diffraction spectra. The effects of annealing on the motion of the labels were dependent on annealing temperature and the type of the samples. Higher temperature annealing decreased the rotational correlation times (τ_c) and their activation energy in high density polyethylene but did not affect those of low density polyethylene. Melting decreases the values of τ_c and ΔE for both high an low density polyethylene samples. The cause of these decreases were attributed to the changing of the sites of the chain-end labels. The motion of the labels appeared to be influenced by the local segmental motion of the polymer main chains.     

Photo-regulated metal coordination of azobenzene polymer having sterically controlled ion binding sites

Summary 2,2-Dimethylazobenzenes having metal chelating ligands at meta-positions were synthesized, and the interaction with metal ions were estimated for syn- and anti-ligands on thermal isomerization. The azobenzenes with the metal-interaction were transformed to vinyl azobenzenes and copolymerized with styrene. The metal extracting ability was found in photo-isomerized polymer having syn-bis(iminodiacetic acid) groups; the selectivity was high for Cu(II) ion.