聚合物膜上的微尺度金属导线在力电耦合作用下的屈曲行为(英文)

研究一种典型的微尺度康铜线/聚合物膜结构在力电耦合作用下的屈曲行为。根据卸载后康铜线从聚合物基底上屈曲的现象,评估康铜线与聚合物基底间的界面韧性。此外,力电耦合作用还会诱发新的失稳模态。在电载荷和拉伸载荷作用下,康铜线易在屈曲时发生断裂。在电载荷和压缩载荷作用下,康铜线易在屈曲区域的顶部发生折叠,偶尔还会向聚合物基底内部方向发生屈曲。分析了这些失稳模态的产生机理。     

Enhanced piezoelectric properties of barium titanate–potassium niobate nano-structured ceramics by MPB engineering

Barium titanate (BaTiO₃, BT)–potassium niobate (KNbO₃, KN) (BT–KN) nanocomplex ceramics with various KN/BT molar ratios were prepared by the solvothermal method. From a transmittance electron microscopy (TEM) observation, it was confirmed that KN layer thickness of the BT–KN nanocomplex ceramics was controlled from 0 to 44 nm by controlling KN/BT molar ratios. Their dielectric constants were measured at room temperature and 1 MHz, and a maximum dielectric constant of around 400 was measured for the BT–KN nanocomplex ceramics with a KN thickness of 22 nm. TEM observation revealed that below KN thickness of 22 nm, BT/KN heteroepitaxial interface was assigned to the strained interface while over 22 nm, the interface was assigned to the relaxed one. These results suggested that the strained heteroepitaxial interface could be responsible for the enhanced dielectric constants.     

Preparation and Characterization of Amphiphilic Lignin Derivatives as Surfactants

Abstract

Acetic acid lignin (AL), one of the organosolv lignins, was modified by polyoxyethylation using commercially available polyethylene glycol diglycidylethers (PEGDE) having various chain lengths in order to generate novel nonionic polymeric surfactants. AL could be converted to the amphiphile by modifying with PEGDE (PEGDE-AL) having more than 9 of the ethylene oxide (EO) repeating units. Although the surface activities of PEG and AL were very limited, PEGDE-AL did strongly depress surface tension of water, and showed clear critical micelle concentrations (CMC). The CMC value of PEGDE-AL could be comparable to a commercial anionic lignin surfactant, lignosulfonate. The surface activity of AL amphiphile was further improved by modification with monoepoxides, ethoxy-(2-hydroxy)-propoxy-polyethylene glycol glycidylether (EPEGGE). The surface tension of water was depressed by the addition of the EPEGGE-AL to the same level as Triton® X-100, which is a commercial PEG-based nonionic surfactant, although there is still room for improvement in CMC value. The hydrophile–lipophile balance (HLB) of these AL amphiphiles was in the range of 11–14, and significant biodegradation was observed. These results suggest that the AL amphiphiles can be used as emulsifier and detergent.     

GAS PERMEANCE BEHAVIOR AT ELEVATED TEMPERATURE IN MESOPOROUS ANODIC OXIDIZED ALUMINA SYNTHESIZED BY PULSE-SEQUENTIAL VOLTAGE METHOD

Mesoporous anodic oxidized alumina (MAOA) capillary tubes with and without a barrier layer have been synthesized by applying a pulse-sequential voltage. The single gas permeances at an elevated temperature and the thermal and hydrothermal stabilities of MAOA were investigated. A highly oriented radial mesopore channel with pore sizes from 40 to 4 nm was formed in the MAOA tubes. Micropores with sizes from 0.4 to 0.8 nm were formed in the barrier layer. The H₂ permeance of MAOA with a barrier layer (barrier type) was approximately 540 times lower than that of MAOA without a barrier layer (block type) at 773 K. The H₂/N₂ permselectivity of the barrier type in the temperature range from 333 to 673 K was 3.4; those of the barrier type at 773 and 823 K were 4.4 and 11, respectively. On the other hand, the H₂/N₂ permselectivities of the block type were from 3.1 to 3.6 in the temperature range from 333 to 773 K. The H₂ permeance and the H₂/N₂ permselectivity of the amorphous silica membrane on the block type were 1.1 × 10^?7 mol/m² · s · Pa and 40 at 773 K, respectively. MAOA synthesized by the pulse-sequential voltage method can be applied to the mesoporous support of the gas separation membrane at elevated temperatures.     

Effect of Dopants on the Distribution of Aluminum and Oxygen Fluxes in Polycrystalline Alumina Under Oxygen Potential Gradients at High Temperatures

The oxygen permeability of Lu‐, Y‐, and Hf‐doped polycrystalline alumina wafers under steep oxygen potential gradients was evaluated at temperatures above 1773 K. Oxygen permeation occurred by the grain‐boundary (GB) diffusion of oxygen from the higher oxygen partial pressure (P_O2) surface to the lower P_O2 surface, and was coincident with GB diffusion of aluminum in the reverse direction. Lu‐ and Y‐doping both suppressed oxygen permeation to the same extent, owing to the decrease in oxygen mobility, but neither had any significant effect on aluminum mobility. Hf‐doping had the opposite effect. The fluxes of oxygen and aluminum at the inflow side in all wafers were significantly smaller than those at the outflow side, regardless of whether or not these dopants were added. Consequently, the intersection of the fluxes shifted to the lower P_O2 side upon Lu‐ and Y‐doping, and to the higher P_O2 side upon Hf‐doping. Furthermore, the effect of dopants on the mass transfer in scales formed by oxidation of FeCrAl‐based alloys at 1300–1500 K was analyzed through predictions of the flux distributions of oxygen and aluminum in the scales.     

Effect of Water on Adsorption Behavior at Polymer/γ-Fe2O3 Interface

The adsorption behavior of a hydroxylated polymer onto γ-Fe₂O₃ particles in a tetrahydrofuran/water solvent system was investigated. The saturation adsorption of the polymer decreased with an increase in the water content of the solvent system, and the degree of dispersion of the magnetic particles in the paint also decreased. It was shown that the water located not at the interface between the particles and the solution but in the solution. Water interacted with the polymer and increased the radius of gyration of the polymer in solution. Thus, the polymer did not interact with the particles, and the particles were prevented from having a high dispersion.     

Crystallization of double crystalline block copolymer/crystalline homopolymer blends: 1. Crystalline morphology

The crystalline morphology formed in binary blends of poly(ε-caprolactone)- block-polyethylene (PCL-b-PE) copolymers and PCL homopolymers has been examined using synchrotron small-angle X-ray scattering (SR-SAXS) and differential scanning calorimetry (DSC) as a function of the homopolymer fraction in the blend. The PE block crystallized first on quenching from a lamellar microdomain structure to set a hard lamellar morphology (PE lamellar morphology) in the blend, followed by the crystallization of PCL chains (i.e., PCL homopolymers + PCL blocks). Two binary blends were studied by considering the miscible state of PCL homopolymers in the microdomain structure: when the PCL homopolymers were uniformly mixed with PCL blocks, they formed a mixed crystal. When the PCL homopolymers were localized between PCL blocks in the microdomain structure, DSC results suggested the possible formation of separate PCL crystals in the PE lamellar morphology. The effect of the advance crystallization of PE blocks on the subsequent crystallization of PCL chains was discussed as compared with the crystalline morphology formed in PCL-block-polybutadiene copolymer/PCL homopolymer blends, where the crystallization of PCL chains started directly from a microdomain structure without forming the hard lamellar morphology.     

Site-Specific Fracture Healing: Comparison between Diaphysis and Metaphysis in the Mouse Long Bone

The process of fracture healing varies depending upon internal and external factors, such as the fracture site, mode of injury, and mechanical environment. This review focuses on site-specific fracture healing, particularly diaphyseal and metaphyseal healing in mouse long bones. Diaphyseal fractures heal by forming the periosteal and medullary callus, whereas metaphyseal fractures heal by forming the medullary callus. Bone healing in ovariectomized mice is accompanied by a decrease in the medullary callus formation both in the diaphysis and metaphysis. Administration of estrogen after fracture significantly recovers the decrease in diaphyseal healing but fails to recover the metaphyseal healing. Thus, the two bones show different osteogenic potentials after fracture in ovariectomized mice. This difference may be attributed to the heterogeneity of the skeletal stem cells (SSCs)/osteoblast progenitors of the two bones. The Hox genes that specify the patterning of the mammalian skeleton during embryogenesis are upregulated during the diaphyseal healing. Hox genes positively regulate the differentiation of osteoblasts from SSCs in vitro. During bone grafting, the SSCs in the donor’s bone express Hox with adaptability in the heterologous bone. These novel functions of the Hox genes are discussed herein with reference to the site-specificity of fracture healing.     

Protective effect of lutein after ischemia-reperfusion in the small intestine

Lutein is a carotenoid mainly found in green leafy vegetables and is located in the macula lutea in the human eye. Since humans cannot synthesise lutein de novo, it must be digested as food. The physiological importance of an orally administered compound depends on its interaction with target tissues. There is little information about the effects of intake of lutein in tissues other than the eyes. The aim of this study was to clarify the protective effect of lutein against oxidative injury using ischemia-reperfusion (I/R) model rats and to determine the relationship between pharmacokinetics and antioxidant activity of lutein. Intestinal I/R was induced by 30-min occlusion of the superior mesenteric artery followed by 60-min reperfusion. After 60 min of reperfusion, intestinal tissue was used for analysis of Evans blue dye extravasation, lipid peroxidation and myeloperoxidase activity. Lutein administered before I/R had a significant protective effect against oxidative injury.     

Study on laser consolidation of metal powder with Yb:fiber laser—Evaluation of line consolidation structure

This study describes the consolidation characteristics of chromium molybdenum steel (SCM) based powder used for rapid tooling. The laser beam used was a Yb:fiber laser with a spot diameter of 45 μm and a maximum power of 40 W. In order to investigate the influence of irradiation conditions on the maximum temperature at the focal area, a two-color pyrometer developed by the authors was used. In addition, the cross section of the consolidated structure was analyzed with an electron probe microanalysis, and the cutting force was measured with a dynamometer. The result showed that the maximum temperature at the focal area was related to the consolidation characteristics of the metal powder. The main parameters which affected the consolidation characteristics were laser power and scan speed of the laser beam. The deposited powder and the plate surface were melted with generated heat and alloyed in the process of the solidification. The specific cutting force was greatly influenced by the consolidation conditions. The highest value of a specific cutting force was obtained when the melting of the powder and the solidification of the molten powder were performed repeatedly and the structure was consolidated linearly.