Pressure dependence of gas permeability in a rubbery polymer

The effect of pressure on gas permeability of a rubbery polymer, 1,2-polybutadiene, is investigated for 15 gases with various molecular sizes and solubilities in the ranges of pressure up to 110 atm at 25°C. The permeability for slightly soluble gases (He, Ne, H₂, N₂, O₂, and Ar) decreases with increasing pressure, and that for soluble gases (CH₄, Kr, CO₂, N₂O, C₂H₄, Xe, C₂H₆, C₃H₆, and C₃H₈) increases with increasing pressure. Logarithms of permeability coefficient versus feed-gas pressure for the slightly soluble gases, CH₄ and Kr, is linear within each pressure range, whereas such plots become convex toward the pressure axis for more soluble gases, such as CO₂, N₂O, C₂H₄, Xe, C₂H₆, C₃H₆, and C₃H₈. By analyzing the pressure dependence of permeability using sorption data of the gases, contributions of concentration and hydrostatic pressure to the gas diffusivity are estimated. © 1996 John Wiley & Sons, Inc.     

Control of the rhodium particle size of the silica-supported catalysts by using microemulsion

The control of the rhodium particle size of silica-supported catalysts by using microemulsion was investigated in terms of the structure of surfactants and organic solvents. The use of nonionic surfactants and anionic surfactants is effective for the preparation of catalysts having narrow size distribution. Especially, in nonionic surfactants, the rhodium particle size varied in the range of 3.0–8.2 nm according to the structure of surfactants and organic solvents regardless of rhodium content. The length of the hydrophilic group of surfactants and the carbon number of n-alcohol as an organic solvent were effective factors for the size control. The rhodium particle size increased with decreasing length of the hydrophilic groups of surfactants and with increasing carbon number of n-alcohol.     

复合喷雾加工法在切削加工过程中的冷却和润滑效果

对喷雾加工法应用于连续切削的可能性进行了探讨。复合喷雾加工法是将冷却性能很好的水形成小颗粒的水雾,并将其同微量植物油油雾同时供给切削区,以降低切削区温度,保证微量切削油的润滑性的加工方法。试验结果证明,复合喷雾加工法对于被认为对切削区供给切削油困难的连续切削,也是十分有效的加工方法。应用这种加工方法可提高加工表面的精度,改善刀具的磨损,并由此实现清洁生产方式。     

Determination of levamisole in livestock products using high performance liquid chromatography

A method is described for the determination of the anthelmintic levamisole in muscle, liver, kidney and fat of cattle, swine and poultry using high performance liquid chromatography with photodiode array detection. Levamisole was extracted from an alkaline sample with ethyl acetate and back-extracted with 0.1 mol/L hydrochloric acid. The extract was applied to an SCX solid-phase extraction column. The column was washed with water and methanol. Levamisole was eluted with a solution of ammonia in methanol. The eluate was evaporated to dryness and the residue was dissolved in the mobile phase and injected into the HPLC system. Mean recoveries from 0.01-0.10 microgram/g fortified muscle, liver, kidney and fat samples ranged from 78.3 to 99.8%. The detection limit for the assay was 0.005 microgram/g.     

Effects of liquid–liquid phase separation on crystallization of poly(ethylene glycol) in blends with isotactic poly(methyl methacrylate)

To analyze the interplay between crystallization and liquid–liquid phase separation (LLPS), isothermal crystallization behavior of poly(ethylene glycol) (PEG) in blends with isotactic poly(methyl methacrylate) (i-PMMA) was investigated by differential scanning calorimetry (DSC). The blend system had an upper critical solution temperature (UCST) type phase diagram. When the crystallization occurred simultaneously with LLPS, the overall crystallization rate was enhanced at high crystallization temperatures T_c, relatively compared with that of neat PEG. This behavior was interpreted by the combination of the effects of spinodal quench depth ?T_s and usual supercooling degree ?T_c, according to the theory of Mitra and Muthukumar, namely, the crystallization rate is enhanced by the concentration fluctuation-assisted nucleation at high T_c. In the crystallization after LLPS proceeded, on the other hand, the overall crystallization rate was slow and less dependent on the blend composition. In addition, it was revealed by small-angle X-ray scattering measurements that amorphous i-PMMA was excluded from the interlamellar region of PEG crystals in SQ as well as WQ.     

Intercalated Polycarbonate/Clay Nanocomposites: Nanostructure Control and Foam Processing

Intercalated polycarbonate (PC)/clay nanocomposites (PCCN)s have been prepared successfully through the melt intercalation method in the presence of a compatibilizer. The internal structure and morphology of the PCCNs has been established by using wide‐angle X‐ray diffraction (WAXD) analyses and transmission electron microscopic (TEM) observations. The morphology of these nanocomposites and degradation of the PC matrix after nanocomposites preparation can be controlled by varying surfactants used for the modification of clay and compatibilizer. The intercalated PCCNs exhibited remarkable improvements of mechanical properties when compared with PC without clay. We also discuss foam processing of one representative PCCN using supercritical CO₂ as a foaming agent.

TEM bright field image of intercalated polycarbonate/synthetic fluorohectorite nanocomposite.     

Miscibility of segmented polyurethane/poly(vinyl chloride) blends

Miscibilities of segmented polyurethanes (SPUs) and poly(vinyl chloride) (PVC) or functionalized poly(vinyl chloride) (FPVC) were studied with dynamic mechanical analysis, differential scanning calorimetry, and X‐ray diffraction. Mechanical properties of the blends were also studied with tensile measurements. The miscibility of the blends depended greatly on the hard‐segment content of SPU and the existence of the functional groups. The combination of SPU with a low hard‐segment content and PVC with functional groups made the blend system miscible. Moreover, controlling the blend composition of SPU/FPVC allowed us to modify the mechanical properties of SPU, where the elongation at break was multiplied without a significant change in its tensile strength. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3022–3029, 2001     

Thermal Expansion of YBa2Cu3O7_xas Determined by High-Temperature X-ray Diffraction under Controlled Oxygen Partial Pressures

The high-temperature phase relationship and thermal expansion coefficient of YBa₂Cu₃O_7-x under constant oxygen nonstoichiometry, x, were determined by high-temperature powder X-ray diffraction analysis under controlled oxygen partial pressure at temperatures up to 800^deg;C. The results are discussed based on reported nonstoichiometry data. The present study showed an orthorhombic-to-tetragonal transition near the composition x = 0.5. The lattice parameter c, perpendicular to the Cu-O plane, showed a maximum at around x = 0.7 to 0.8. In the ortho-rhombic phase, the lattice parameters a and b along the Cu-O plane were essentially constant for x < 0.2. For 0.2 < x < ∼ 0.5, a increased and b decreased with x. In the tetragonal phase, with x < ∼ 0.5, the lattice parameter a decreased with x. The thermal expansion coefficient, α, along the c-axis ranged from 19 × 10^-6 to 25 × 10^-6-K^-1, whereas a along the a- and b-axes ranged from 12 × 10^-6 to 22 × 10^-6-K^-1 at 400° to 800^deg;C, and these values were very small below 400^deg;C. It was found that a, b, and α along the a- and b-axes are smaller when the oxygen content along the respective axes is less, while the area of the ab plane and its thermal expansion coefficient are larger when the deviation of the oxygen content from the stoichiometric compositions of YBa₂Cu₃O₇ or YBa₂Cu₃O₆ is larger. Changes of x and temperature affected c more strongly than a and b.     

Synthesizing activated carbons from resins by chemical activation with K2CO3

We prepared activated carbons from phenol-formaldehyde (PF) and urea-formaldehyde (UF) resins by chemical activation with K₂CO₃ with impregnation during the synthesis of the resins. The influence of carbonization temperature (773-1173 K) on the pore structure (specific surface area and pore volume) and the temperature range at which K₂CO₃ worked effectively as an activation reagent, were investigated. The specific surface area and micropore volume of PF-AC and UF-AC increased with an increase of carbonization temperature in the range of 773-1173 K. We prepared activated carbon with well-developed micropores from PF, and activated carbon with high specific surface area (>3000 m²/g) and large meso-pore volume from UF. We deduced the activation mechanism with thermogravimetry and X-ray diffraction. In preparing activated carbon from PF, K₂CO₃ was reduced by carbon in the PF char. The carbon was removed as CO gas resulting in increased specific surface area and pore volume above 1000 K. In preparing AC from UF, above 900 K the carbon in UF char was consumed during the K₂CO₃ reduction step.     

Development and Regeneration of Muscle,Tendon, and Myotendinous Junctions in Striated Skeletal Muscle

Owing to a rapid increase in aging population in recent years, the deterioration of motor function in older adults has become an important social problem, and several studies have aimed to investigate the mechanisms underlying muscle function decline. Furthermore, structural maintenance of the muscle–tendon–bone complexes in the muscle attachment sites is important for motor function, particularly for joints; however, the development and regeneration of these complexes have not been studied thoroughly and require further elucidation. Recent studies have provided insights into the roles of mesenchymal progenitors in the development and regeneration of muscles and myotendinous junctions. In particular, studies on muscles and myotendinous junctions have—through the use of the recently developed scRNA-seq—reported the presence of syncytia, thereby suggesting that fibroblasts may be transformed into myoblasts in a BMP-dependent manner. In addition, the high mobility group box 1—a DNA-binding protein found in nuclei—is reportedly involved in muscle regeneration. Furthermore, studies have identified several factors required for the formation of locomotor apparatuses, e.g., tenomodulin (Tnmd) and mohawk (Mkx), which are essential for tendon maturation.