Atom transfer radical polymerization of graft chains onto polyethylene film initiated at tribromomethyl unit introduced by electron beam irradiation

A novel process for graft polymerization onto a polyethylene (PE) film using atom transfer radical polymerization (ATRP) was examined. First, a PE film irradiated with an electron beam was treated with carbon tetrabromide, thereby introducing tribromomethyl groups. The number of tribromomethyl groups introduced onto the film could be controlled by adjusting the electron beam irradiation dose. Methyl methacrylate (MMA) was then graft‐polymerized by ATRP in the initiator‐introduced PE film in the presence of a copper catalyst. Based on FTIR spectra from the PMMA grafted films, the behavior of graft polymerization reactions on the film surface and inside the film are discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of magnetic fluid having active-gas resistance and ultra-low vapor pressure for magnetic fluid vacuum seals

The magnetic fluid, having an ultra-low vapor pressure property of 7·0×10⁻¹⁰ Pa at 293 K, was prepared. Hexafluoropropylene oxide polymer oil having high molecular weight was used as base oil. Magnetic particles were dispersed by using two types of new designed and synthesized hexafluoropropylene oxide acid derivative surfactants. The obtained magnetic fluid had a saturation magnetization of 35·0 mT, its magnetite particles were dispersed stably and showed a superior resistance to active gasses. It was ascertained that the magnetic fluid vacuum seal using the prepared fluid had the ultra high vacuum performance.     

Ambient pressure synthesis of La2LiHO3 as a solid electrolyte for a hydrogen electrochemical cell

The capability of La₂LiHO₃ as a H⁻ conductive solid electrolyte has recently been demonstrated, which has suggested the possibility of developing electrochemical devices based on H⁻ conduction. However, the performance of La₂LiHO₃ as a solid electrolyte has not yet been fully clarified. In this study, we prepared La₂LiHO₃ sintered pellets by a conventional solid-state reaction with LiH flux under ambient pressure and characterized the crystal structure and thermal stability (to moisture, ambient air, and oxygen) by neutron and X-ray diffraction measurements. The produced sintered pellets exhibited an activation energy of 69.2 kJ/mol, which is consistent with the value of the sample synthesized by the high-pressure method. The gas-sealing properties of the sintered La₂LiHO₃ pellets as the H⁻ conductive solid electrolyte were confirmed by measuring the electromotive force using a hydrogen concentration cell.     

Evaluation of enhanced conduction-corrected modified effective temperature ETFe as the outdoor thermal environment evaluation index

The purpose of this paper is made to clarify that the relationship between the human physiological and psychological responses and the enhanced conduction-corrected modified effective temperature ETFe as the outdoor thermal environment evaluation index upon the human body. Environmental factors and human physiological and psychological responses were measured. It was made clear that the variables by which summer outdoor environmental factors influence the thermal sensation vote are heat conduction, humidity and short-wave solar radiation. The variables that affect the thermal comfort vote are air velocity, heat conduction and humidity. ETFe, into which the environmental factors that are the variables for human response are incorporated, showed good correspondence with the thermal sensation vote. Similarly, ETFe has a good correspondence with thermal comfort vote. The usage of ETFe as a thermal environment evaluation index for summer outdoor spaces is valid. The threshold for the human body with regards to thermal environment stimuli in an outdoor space is higher than the thermal environment stimuli in a summer indoor space.     

Effect of modification and ceramic particles on solidification behavior of aluminum-matrix composites

Thermal analysis is used to establish the relationship between solidification history and the microstructure of SiC particulate reinforced Al-Si alloy-matrix composites. The results show that cooling curves are influenced by the presence of SiC particles and by strontium modification. The eutectic growth temperature of SiC_P/359 composites modified with Sr lies in the range of 840 to 843 K, i.e., about 5 to 7 K higher than that of Sr-modified unreinforced 359. For the same composite, the eutectic undercooling is higher with Sr modification than without. The eutectic solidification time of the composites is shorter than that of the unreinforced base alloy because of the presence of the ceramic particles. Strontium modification has the tendency to extend the eutectic solidification time. Microstructure analysis reveals that Sr modification has a refining effect on eutectic silicon for the composites, and SiC particles in the composite melt serve as the substrates for eutectic Si phase nucleation.     

Sources of Ca2+ in relation to generation of acetylcholine-induced endothelium-dependent hyperpolarization in rat mesenteric artery

1. The aim of the present study was to identify the sources of Ca2+ contributing to acetylcholine (ACh)-induced release of endothelium-derived hyperpolarizing factor (EDHF) from endothelial cells of rat mesenteric artery and to assess the pathway involved. The changes in membrane potentials of smooth muscles by ACh measured with the microelectrode technique were evaluated as a marker for EDHF release. 2. ACh elicited membrane hyperpolarization of smooth muscle cells in an endothelium-dependent manner. The hyperpolarizing response was not affected by treatment with 10 microM indomethacin, 300 microM NG-nitro-L-arginine or 10 microM oxyhaemoglobin, thereby indicating that the hyperpolarization is not mediated by prostanoids or nitric oxide but is presumably by EDHF. 3. In the presence of extracellular Ca2+, 1 microM ACh generated a hyperpolarization composed of the transient and sustained components. By contrast, in Ca(2+)-free medium, ACh produced only transient hyperpolarization. 4. Pretreatment with 100 nM thapsigargin and 3 microM cyclopiazonic acid, endoplasmic reticulum Ca(2+)-ATPase inhibitors, completely abolished ACh-induced hyperpolarization. Pretreatment with 20 mM caffeine also markedly attenuated ACh-induced hyperpolarization. However, the overall pattern and peak amplitude of hyperpolarization were unaffected by pretreatment with 1 microM ryanodine. 5. In the presence of 5 mM Ni2+ or 3 mM Mn2+, the hyperpolarizing response to ACh was transient, and the sustained component of hyperpolarization was not observed. On the other hand, 1 microM nifedipine had no effect on ACh-induced hyperpolarization. 6. ACh-induced hyperpolarization was nearly completely eliminated by 500 nM U-73122 or 200 microM 2-nitro-4-carboxyphenyl-N, N-diphenylcarbamate, inhibitors of phospholipase C, but was unchanged by 500 nM U-73343, an inactive form of U-73122. Pretreatment with 20 nM staurosporine, an inhibitor of protein kinase C, did not modify ACh-induced hyperpolarization. 7. These results indicate that the ACh-induced release of EDHF from endothelial cells of rat mesenteric artery is possibly initiated by Ca2+ release from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ pool as a consequence of stimulation of phospholipid hydrolysis due to phospholipase C activation, and maintained by Ca2+ influx via a Ni(2+)- and Mn(2+)-sensitive pathway distinct from L-type Ca2+ channels. The Ca(2+)-influx mechanism seems to be activated following IP3-induced depletion of the pool.     

Morphology rearrangement of PEO and PG blocks of amphiphilic copolymer particles in solution affected by FeCl<Subscript>3</Subscript>/acidified water addition

The present contribution describes the preparation of nanosized aggregates by dissolving diblock copolymers consisting of hydrophobic polystyrene (PS) with randomly distributed short diene (D) moieties and hydrophilic polyether (polyethylene oxide (PEO) or polyglycidol (PG)) blocks in selective solvents. Inducing structural and/or size changes of the aggregates by addition of FeCl₃/acidified H₂O to the system is experimented. Dynamic light scattering (DLS) and size exclusion chromatography (SEC) measurements reveal resizing of the particles whilst adding FeCl₃/acidified H₂O. Further the structure and size of P(SD-EO/G) block copolymer corе-shell particles are determined by Diffusion Ordered NMR Spectroscopy (DOSY) which indicates a partial reversal of the core-shell structure upon the addition of FeCl₃/acidified H₂O. Transmission electron microscopy provides a more detailed insight on the morphology, shape and size distribution of the aggregates. For comparison, the change in the particle size under identical conditions for species of preliminary stabilized core-shell morphology is monitored as well.     

Microflora associated with primary endodontic infections: Correlations among sem evaluation,clinical features,and radiographic findings

The aim of the present study was to characterize, by means of SEM, primary endodontic infections and to correlate with clinical and radiographic findings. Twelve (12) human extracted teeth (19 roots) presenting primary endodontic infection were examined. SEM qualitative observations of bacterial and defense cells, their features and distribution within the root canal lumen and root dentine were recorded for association with clinical and radiographic tabled data. Although a direct correlation between biofilm composition and clinical/radiographic findings was not established, structural organization and distribution of the biofilm, as well as the characteristics of host response, could be easily related to those features. Bacterial biofilm was predominant at the apical third. Symptomatic apical periodontitis was related to presence of bacterial biofilm all thirds. Defense cells could be seen in the apical third of some samples. These cells were present in all thirds in some of the cases with open cavities. The correlations performed in this study allowed a better understanding of the picture of primary endodontic infection, host response and relevant clinical features. The combined use of scanning electron microscopy with clinical and radiographic evaluation has the potential to overcome some limits of the current knowledge related to pulpal and periapical diseases, providing important insights for improving treatment strategies. Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.     

Semi‐Automatic Conversion of 3D Shape into Flat‐Foldable Polygonal Model

This paper presents a method that can convert a given 3D mesh into a flat‐foldable model consisting of rigid panels. A previous work proposed a method to assist manual design of a single component of such flat‐foldable model, consisting of vertically‐connected side panels as well as horizontal top and bottom panels. Our method semi‐automatically generates a more complicated model that approximates the input mesh with multiple convex components. The user specifies the folding direction of each convex component and the fidelity of shape approximation. Given the user inputs, our method optimizes shapes and positions of panels of each convex component in order to make the whole model flat‐foldable. The user can check a folding animation of the output model. We demonstrate the effectiveness of our method by fabricating physical paper prototypes of flat‐foldable models.     

New three-dimensional electrode structure for the lithium battery: Nano-sized γ-Fe2O3 in a mesoporous carbon matrix

A new electrode structure based on a three-dimensional mesoporous matrix was developed. Nanoparticles of γ-iron oxide (Fe₂O₃) were introduced into the mesopores of a carbon matrix (mesoporous carbon, CMK-3) by oxidizing metallic iron, which was electroplated in the matrix. The resulting structure was found to have a high charge-discharge capacity when used as the positive electrode of a lithium battery. The iron oxide nanoparticles bonded tightly to the electrically conductive electrode framework, and showed a high activity for the electrochemical reaction: Fe₂O₃ + 6Li → 3Li₂O + 2Fe.