A study of the fatigue limit of copper

This paper shows that, in fatigue tests on copper, a great number of cycles beyond expectation is necessary for determining the fatigue limit. An ultrahigh frequency fatigue testing machine was used andS-N curves covering 10¹⁰ cycles were obtained for annealed specimens and for stretched ones. In annealed copper, the fatigue limit appeared at about 9.8 × 10⁹ cycles. Observations were made on the development of slip bands and substructures in the course of a test at the strain level (3.8 × 10^-4) of the fatigue limit. The slip bands continued to develop up to about 9 × 10⁹ cycles, but remained unchanged if further cycled. On a searching examination of the behavior of microcracks, one end of which stayed in a grain without propagation, it was proved that fatigue hardening was responsible for the existence of the fatigue limit. Contrary to expectation, cell structures were found after 10¹⁰ cycles in such a low strain fatigue. In stretched copper, however, microcracks continued to grow even in the stage beyond 10¹⁰ cycles when fatigued at the strain level of the fatigue limit inferred from itsS-N curve.     

Design of novel sheet-shaped chitosan hydrogel for wound healing: A hybrid biomaterial consisting of both PEG-grafted chitosan and crosslinkable polymeric micelles acting as drug containers

In this study, we successfully prepared a novel “sheet-shaped” chitosan hydrogel for wound healing consisting of both PEG-g-chitosan and a crosslinkable polymeric micelle. The study's findings clarify that the PEG modification percentage (PMP) of PEG-g-chitosan increased proportionally as the weight ratio of PEG/chitosan increased. Furthermore, the positive second virial coefficient of PEG-g-chitosans from a Debye plot strongly suggests that the PEG modification greatly improved the solubility of the water-insoluble chitosan. Finally, the “sheet-shaped” “flexible” hydrogel formed by mixing solutions containing either PEG-g-chitosan with moderate PMP or polymeric micelles exhibited the highest storage modulus. The sheet itself exhibited an attractive feature insofar as polymeric micelles, which can act as drug containers facilitating the incorporation and the gradual release of drugs, are covalently immobilized in the polymeric network of the hydrogel. The results obtained in the present study show that the hybrid PEG-g-chitosan hydrogel containing crosslinkable polymeric micelles has the potential to address the need for novel functional biomaterials.     

Structural classification and similarity measurement of malware

This paper proposes a new lightweight method that utilizes the growing hierarchical self‐organizing map (GHSOM) for malware detection and structural classification. It also shows a new method for measuring the structural similarity between classes. A dynamic link library (DLL) file is an executable file used in the Windows operating system that allows applications to share codes and other resources to perform particular tasks. In this paper, we classify different malware by the data mining of the DLL files used by the malware. Since the malware families are evolving quickly, they present many new problems, such as how to link them to other existing malware families. The experiment shows that our GHSOM‐based structural classification can solve these issues and generate a malware classification tree according to the similarity of malware families. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

TEM and HAADF-STEM study of the structure of Au nano-particles on CeO<Subscript>2</Subscript>

The structure and growth process of Au particles on CeO₂ were observed by the transmission electron microscope (TEM) equipped with the high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) system. The growth of Au particles on CeO₂ was shown to be mainly Ostwald ripening under heating at various temperatures, although it is suppressed in the hydrogen atmosphere. In the HAADF-STEM observation of Au/CeO₂ interfaces with the orientation relationship of (111)[1–10]Au//(111)[1–10]CeO₂, (111)[−110]Au//(111)[1–10]CeO₂ and atomic columns of Au and Ce were successfully resolved, and the interface structure was analyzed in details for the first time.     

Synthesis of dioctyl sulfosuccinate-doped polypyrrole grains by aqueous chemical oxidative polymerization and their use as light-responsive liquid marble stabilizer

Polypyrrole grains are synthesized by aqueous chemical oxidative polymerization using ferric chloride as an oxidant in the presence of bis(2-ethylhexyl) sulfosuccinate sodium salt as both a dopant and a hydrophobizing agent. The resulting grain products are characterized in terms of their size, morphology, surface and bulk chemical compositions, hydrophilicity-hydrophobicity balance, (photo) thermal property, and electrical conductivity. Scanning electron microscopy studies indicate that the grains are aggregates of atypical primary grains with submicrometer size. Elemental microanalysis and thermogravimetric analysis confirm that the polypyrrole is preferably doped with dioctyl sulfosuccinate compared with chloride ion, and dioctyl sulfosuccinate/chloride ion dopant ratio increases with an increase of bis(2-ethylhexyl) sulfosuccinate sodium salt concentration in the polymerization systems. The grains show near-infrared light-to-heat photothermal property, which is confirmed by thermography. The data obtained through X-ray photoelectron spectroscopy indicate the presence of dioctyl sulfosuccinate dopants on the surface of the grains, and therefore the dried polypyrrole grains show hydrophobic character. The dried grains can work as a light-responsive liquid marble (LM) stabilizer. Motions of the LM can be driven by near-infrared laser irradiation-induced Marangoni flow on planar air-water surface. The release of internal liquid can be achieved by controlled disruption of the LM via external stimulus application.     

Analytical TEM study on structural changes of Au particles on cerium oxide using a heating holder

The structure changes of Au nano-particles supported on CeO₂ were observed by using an analytical transmission electron microscope (TEM) with a specimen heating holder. The disintegration and growth of Au particles on CeO₂ were successfully observed in the atomic scale. In situ observation of Au particles at elevated temperature reveals that the Au particles on CeO₂ grow by Ostwald ripening process through surface diffusion. Iridium particles on CeO₂ were also observed during the heating process for comparison. The growth mode of Au particles is quite different from that of Ir.     

Transcriptional Induction of Metallothionein by Tris(pentafluorophenyl)stibane in Cultured Bovine Aortic Endothelial Cells

Vascular endothelial cells cover the luminal surface of blood vessels and contribute to the prevention of vascular disorders such as atherosclerosis. Metallothionein (MT) is a low molecular weight, cysteine-rich, metal-binding, inducible protein, which protects cells from the toxicity of heavy metals and active oxygen species. Endothelial MT is not induced by inorganic zinc. Adequate tools are required to investigate the mechanisms underlying endothelial MT induction. In the present study, we found that an organoantimony compound, tris(pentafluorophenyl)stibane, induces gene expression of MT-1A and MT-2A, which are subisoforms of MT in bovine aortic endothelial cells. The data reveal that MT-1A is induced by activation of both the MTF-1–MRE and Nrf2–ARE pathways, whereas MT-2A expression requires only activation of the MTF-1–MRE pathway. The present data suggest that the original role of MT-1 is to protect cells from heavy metal toxicity and oxidative stress in the biological defense system, while that of MT-2 is to regulate intracellular zinc metabolism.     

Studies on composites from wood and polypropylenes. II

Composites of polypropylene (PP) or maleic-anhydride-modified polypropylene (MPP) with refiner ground pulp (RGP) were prepared under various kneading conditions (mixing temperature, rate of rotation, and mixing time) and evaluated for their tensile strength (σ_max), break elongation (?_max), and Young's modulus (E). Particularly, for the rate of rotation, fiber length distribution and its fibrillation were investigated in connection with mechanical properties of the composites. Also evaluated in this study was the effect of modifiers of PP on the properties. Modified PP that can be grafted or can have affinity to RGP was proved to improve the tensile strength of the molded composites as the RGP content increases, while the strength was decreased for PP–RGP composite without a modifier. MPP was also evaluated as a compatibilizer for the PP–RGP composites, and a tremendous improvement of tensile strength was achieved with MPP addition of only 2.5%, indicating that MPP can act as a compatibilizer in its system. These lines of evidence is interpreted to be caused from the improvement of the adhesion between RGP and PP through localizing MPP at the interface of these two components.     

Liquefaction and product identification of corn bran (CB) in phenol

The liquefaction of corn bran (CB) was successfully conducted by using three different liquefaction conditions. Among them, catalyzed liquefaction at high pressure and temperature (180–220°C) using phenol was the most effective for the liquefaction of CB. Both the phenol/CB ratio and the catalyst content affected the extent of the liquefaction. The decomposed components of CB did not show high reactivity toward phenol when liquefied without a catalyst. Thermal‐flow properties of the phenolated CB and flexural properties of the phenolated CB‐based moldings were influenced by the amount of combined phenol and were comparable to those of the commercial novolak or phenolated wood. The effect of molding time and filler content on the flexural properties is also presented. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 311–318, 2000     

Solubilization of single-walled carbon nanotubes by entanglements between them and hyperbranched phenolic polymer

Hyperbranched phenolic polymer (HBP) was prepared by Lewis acid-catalyzed polycondensation of bifunctional phenolic monomer with trifunctional phenolic monomer. By choosing an appropriate Lewis acid, HBP was successfully obtained. By using physical adsorption of HBP on a single-walled carbon nanotube (SWCNT) surface, solubilization of SWCNTs was examined. SWCNTs were soluble with extended branches of HBP in N,N-dimethylformamide (DMF) solution, while they were insoluble in a linear phenolic polymer. In the presence of shrinking branches of HBP in tetrahydrofuran, SWCNTs were hardly soluble. Entanglements between extended branches of HBP and SWCNT in DMF solution resulted in high solubility of SWCNTs.