Magnetization distribution of magnetic vortex of amorphous FeSiB investigated by electron holography and computer simulation

The three-dimensional spin structure of the magnetic vortex of FeSiB, an amorphous soft magnetic material, was investigated by holography observation and computer simulation. Magnetization distribution in the neighborhood of the vortex center was estimated from the phase distribution obtained by holography observation. To confirm this magnetization distribution, sample-tilting experiments were performed: when the sample was tilted with respect to the electron beam direction, the phase-image center was found to shift along the tilting axis. Finite-element computer simulation was carried out to estimate the amount of shifts of the phase-image center in the sample tilting from the experimental magnetization distributions in the no sample-tilting conditions. We found that the simulated shifts of the phase-image center were in good agreement with those in the sample-tilting experiment, thus confirming the magnetization distribution near the vortex center obtained by holography observation.     

Biomass-based composites from poly(lactic acid) and wood flour by vapor-phase assisted surface polymerization

To prepare biomass-based composites in an environmentally benign manner, vapor-phase assisted surface polymerization (VASP) was applied to prepare the composites from wood flour and poly(l-lactic acid) (PLLA) without solvent. VASP of l,l-lactide successfully proceeded on the wood flour surfaces, resulting in surface coverage by newly generated PLLA. For obtained PLLA/wood flour composites, it was clarified that grafting of PLLA on wood flour surfaces had occurred to form covalently bonded composites, with the accumulated PLLA layers having crystallized in situ during VASP. Resulting PLLA layers showed very high crystallinity of 79.2% and a high melting point close to the equilibrium melting point. Moreover, thermal degradation behavior of the composites suggested a cooperative degradation manner of the components.     

SYNTHETIC HYDROGELS AS SCAFFOLDS FOR MANIPULATING ENDOTHELIUM CELL BEHAVIORS

Synthetic hydrogels can be used as scaffolds that not only favor endothelial cells (Ecs) proliferation but also manipulate the behaviors and functions of the Ecs. In this review paper, the effect of chemical structure, Young's modulus (E) and zeta potential (ζ) of synthetic hydrogel scaffolds on static cell behaviors, including cell morphology,proliferation,cytoskeleton structure and focal adhesion, and on dynamic cell behaviors, including migration velocity and morphology oscillation, as well as on EC function such as anti-platelet adhesion, are reported. It was found that negatively charged hydrogels, poly(2-acrylamido-2-methylpropanesulfonic sodium) (PNaAMPS) and poly(sodium pstyrene sulphonate)(PNaSS), can directly promote cell proliferation, with no need of surface modification by any cell-adhesive proteins or peptides at the environment of serum-containing medium. In addition, the Young's modulus (E) and zeta potential (ζ) of hydrogel scaffolds are quantitatively tuned by copolymer hydrogels, poly(NaAMPS-co-DMAAm) and poly(NaSS-co-DMAAm), in which the two kinds of negatively charged monomers NaAMPS and NaSS are copolymerized with neutral monomer, N,N-dimethylacrylamide (DMAAm). It was found that the critical zeta potential of hydrogels manipulating EC morphology, proliferation, and motility is ζcritical= -20.83 mV and ζcritical= -14.0 mV for poly(NaAMPS-co-DMAAm) and poly(NaSS-co-DMAAm), respectively. The above mentioned EC behaviors well correlate with the adsorption of fibronectin,a kind of cell-adhesive protein, on the hydrogel surfaces. Furthermore, adhered platelets on the EC monolayers cultured on the hydrogel scaffolds obviously decreases with an increase of the Young's modulus (E) of the hydrogels, especially when E > 60 kPa. Glycocalyx assay and gene expression of Ecs demonstrate that the anti-platelet adhesion well correlates with the EC-specific glycocalyx. The above investigation suggests that understanding the relationship between physic-chemical properties of synthetic hydrogels and cell responses is essential to design optimal soft and wet scaffolds for tissue engineering.     

主链电荷型高分子与表面活性剂复合物的形成及结构研究

合成了主链带电荷的阳离子高分子聚N,N二甲十二烷基溴化铵（以下简单称12,12-ionene),研究了它与阳离子表面活性剂之间的相互作用及复合物的形成过程,研究结果表明,表面活性对高分子的吸附存在两种形式：一种是等化学量的1：1复合物沉淀的形成;另一种是非等化学量的可溶的复合物的形成,复合物的形成机理被认为活性剂与高分子间的静电相互作用和疏水性相互作用二者的协同,通过X射线衍射分析方法对复合物结构研究表明,复合物可形成规整的分子及超分子结构排列。     

Polymer gels as artificial soft tissue

Soft tissue consists a main body of biological systems. It is made of hydrogels mainly composed of extra cellular matrix (ECM), which is the three-dimensional highly organized and inter-woven network of proteins and polysaccharides. ECM has three symbolic roles. They are pertinent and excellent mechanical performance, extremely low friction, and effective and selective transportation of solute molecules for cell viability. One of the important goals for gel science would be to design and create hydrogels with critical parameters, which natural tissues possess and eventually to replace them with artificial one.     

Ultra-high-precision time control system over any long time delay for laser pump and synchrotron x-ray probe experiment

An ultra-high-precision clock system for long time delay has been developed for picosecond time-resolved x-ray diffraction measurements using synchrotron radiation (SR) pulses and synchronized femtosecond laser pulses. The time delay control between pump laser pulse and the probe SR pulse was achieved by combining an in-phase quadrature modulator and a synchronous counter. This method allowed us to change the delay time by a nearly infinite amount while maintaining the precision of +/-8.40 ps. Time-resolved diffraction measurements using the delay control system were demonstrated for precise measurement of an acoustic velocity in a single crystal of gallium arsenide.     

Biohydrogen production from biomass and industrial wastes by dark fermentation

Hydrogen is a clean energy carrier which has a great potential to be an alternative fuel. Abundant biomass from various industries could be a source for biohydrogen production where combination of waste treatment and energy production would be an advantage. This article summarizes the dark fermentative biohydrogen production from biomass. Types of potential biomass that could be the source for biohydrogen generation such as food and starch-based wastes, cellulosic materials, dairy wastes, palm oil mill effluent and glycerol are discussed in this article. Moreover, the microorganisms, factors affecting biohydrogen production such as undissociated acid, hydrogen partial pressure and metal ions are also discussed.     

Relationship between NAFLD and Periodontal Disease from the View of Clinical and Basic Research,and Immunological Response

Periodontal disease is an inflammatory disease caused by pathogenic oral microorganisms that leads to the destruction of alveolar bone and connective tissues around the teeth. Although many studies have shown that periodontal disease is a risk factor for systemic diseases, such as type 2 diabetes and cardiovascular diseases, the relationship between nonalcoholic fatty liver disease (NAFLD) and periodontal disease has not yet been clarified. Thus, the purpose of this review was to reveal the relationship between NAFLD and periodontal disease based on epidemiological studies, basic research, and immunology. Many cross-sectional and prospective epidemiological studies have indicated that periodontal disease is a risk factor for NAFLD. An in vivo animal model revealed that infection with periodontopathic bacteria accelerates the progression of NAFLD accompanied by enhanced steatosis. Moreover, the detection of periodontopathic bacteria in the liver may demonstrate that the bacteria have a direct impact on NAFLD. Furthermore, Porphyromonas gingivalis lipopolysaccharide induces inflammation and accumulation of intracellular lipids in hepatocytes. Th17 may be a key molecule for explaining the relationship between periodontal disease and NAFLD. In this review, we attempted to establish that oral health is essential for systemic health, especially in patients with NAFLD.     

Structural changes of micropores in carbons by chemical vapor infiltration of carbon

Chemical vapor infiltration is now being used to produce advanced materials for aerospace applications. It is also applicable to carbons to enhance the resistance against oxidation. In the present study, methane pyrolysis was conducted for several kinds of carbons such as electrode-grade graphite, electrode-grade carbon, coke and activated charcoal. The structural change of micropores (radius < 10 nm) accompanying infiltration and oxidation was investigated because oxidation is considered mainly to occur in such small pores due to their large specific surface area. The change of macropores measured by mercury porosimeter is also shown for comparison with that of fine pores. Pore-size distribution measured by the BET method have shown that the filling mode depends on the pore structure of carbons.