Design for improved adhesion of fluorine-incorporated hydrogenated amorphous carbon on metallic stent: Three-layered structure with controlled surface free energy

Hydrogenated amorphous carbon (a-C:H) or element-incorporated a-C:H have attracted much attention as coating materials on coronary artery stents owing to their outstanding properties. However, their applications have been limited because of poor adhesion to metallic materials. The present work was thus aimed at improving the adhesive property of a-C:H-based film on a stent by introducing interlayers with controlled surface free energies.Here we propose a three-layered coating for a SUS316L stent, comprising fluorine-incorporated a-C:H (a-C:H:F), silicon-incorporated a-C:H (a-C:H:Si), and hydrogenated amorphous silicon carbide (a-SiC:H) layers (from top to bottom). Each layer was deposited using a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method, and the surface free energy of each layer was controlled by the experimental parameters. Thereafter, the three-layer-coated stent was expanded and evaluated under a scanning electron microscope (SEM) in order to determine whether or not cracking or delamination had occurred. It can be seen from the SEM images that the occurrence of cracks or delamination was markedly suppressed even in the bent region of the stent after expansion, where the plastic deformation is highly localized when stents are expanded. This indicates that the method we applied in this work can serve as one approach to overcoming the limitation described above.     

The Effects of Wet-Milled Wood Flour on the Mechanical Properties of Wood Flour/Polypropylene Composites

The sizes and shapes of wet ball-milled wood flour were investigated based on their average particle size, size distribution, their solution viscosity, and scanning electron microscopy images. The ball-milling conditions were combinations of rotational speed (150, 200, and 250 rpm) and milling time (1 to 16 h). The average diameter of the wood flours decreased and the degree of fibrillation of the wood fibers increased with the ball-milling time at each rotational speed. Ball-milled wood flours having the same average particle size had similar surface fibrils that were tens to hundreds of nanometers wide. Ball-milling at 200 or 250 rpm could pulverize just as effectively as that at 150 rpm because the size reduction and fibrillation progressed more quickly. Tensile and bending properties of the composites prepared from the ball-milled wood flour (4 wt% in polypropylene) were evaluated. Morphological changes in the wood fillers had little effect on the properties of the composites. The tensile and bending properties of the composites containing the wood filler were 10% higher than those for the unfilled resin.     

The Relationship between Dioxin Congeners in the Breast Milk of Vietnamese Women and Sister Chromatid Exchange

The aim of this study was to clarify the relationship between dioxin concentrations in breast milk and the sister chromatid exchange (SCE) frequency in women from herbicide-sprayed and non sprayed areas. Blood samples were taken from 21 women with high TCDD (tetrachlorodibenzo-p-dioxin) levels from sprayed areas, 23 women with moderate TCDD levels from sprayed areas, and 19 women from non sprayed areas to determine their SCE frequency. The SCE frequencies for the high and moderate TCDD groups from the sprayed area and for the non sprayed area group were 2.40, 2.19, and 1.48 per cell, respectively. Multiple regression analysis showed that the standardized β values for 1,2,3,6,7,8-hexaCDD (β = 0.60), 1,2,3,4,6,7,8-heptaCDD (β = 0.64), and octaCDD (β = 0.65) were higher than those for TCDD (β = 0.34) and 1,2,3,7,8-pentaCDD (β = 0.42). The adjusted R² value for polyCDDs (R² = 0.38) was higher than that for polyCDD toxic equivalents (TEQ (toxic equivalents); R² = 0.23). This study therefore shows that levels of hexa-, hepta-, and octaCDD, which were previously regarded as being less toxic than TCDD, are closely related to SCE frequency and that the level of dioxin (pg/g lipid) is potentially more useful as an indicator than TEQ value for explaining SCE frequency.     

Improving thermostability of phosphatidylinositol-synthesizing Streptomyces phospholipase D

Aimed to produce thermostable phosphatidylinositol (PI)-synthesizing phospholipase D (PLD), we initiated site-directed combinatorial mutagenesis followed by high-throughput screening. Previous site-directed combinatorial mutagenesis of wild-type Streptomyces PLD produced a mutant, DYR (W187D/Y191Y/Y385R) with PI-synthesizing ability. Deriving PI as a product of transphosphatidylation between phosphatidylcholine and myo-inositol, with myo-inositol in excess at high-temperature reaction conditions can increase yield due to enhanced solubility of this substrate. Thus, we improved DYR's thermostability by introduction of random mutations into selected amino acid positions having high B-factor. Screening of the libraries under restricted conditions yielded single-point mutants, specifically D40H, T291Y and R329G. Combinations of these point mutations yielded double (D40H/T291Y, D40H/R329G and T291Y/R329G) and triple (D40H/T291Y/R329G) mutants. PI synthesis at elevated temperatures pointed at D40H/T291Y as the most efficient enzyme. Circular dichroism analysis revealed D40H/T291Y to have increased melting temperature and postponed onset of thermal unfolding compared with DYR. Thermal tolerance study at 65°C confirmed D40H/T291Y's thermostability as its half-inactivation time was 8.7 min longer compared with DYR. This mutant had significantly less root-mean-square deviation change compared with DYR and showed no change in root-mean-square fluctuation when temperature shifts from 40 to 60°C, as determined by molecular dynamics analysis. Acquired different degrees of thermostability were also observed for several other DYR mutants.     

Voting for highway construction in economic geography

This paper investigates the efficiency of voting for provision of transportation infrastructure such as highways, and discusses the effect on regional structure. The salient conclusions of this study show that voting and political competition engender overprovision of large-scale transportation infrastructure. In addition, consideration of industrial location reveals that the provision of transportation infrastructure exerts a negative effect on development of rural areas.     

A prototype safety system for new on-the-job training (OJT) in an anthropocentric cell manufacturing system

The anthropocentric cell manufacturing system (ACMS) discussed consists of a skill-based manufacturing scheduling system, a new on-the-job training (New OJT) system and a safety system. The New OJT was developed using e-learning and automated guided vehicle (AGV)-arm robot as a teacher for CNC machine training. Since the machines and the AGV-arm robot are automatic devices, controlled by computer programs, the dangers might arise during training. Therefore, the safety system is required to ensure that a learner will be safe. We propose a prototype of safety system with designed machine-protection in order to protect the learner from dangerous behaviours during a level 1 training of a New OJT in ACMS. The machine-protection focused on protection from danger using image processing with a background subtraction technique and comparison of objects' position. We also evaluated safety assessments of the learners, consisting of human error probabilities (HEP) and a human error rate (HER). The prototype of this developed safety system showed that the machine-protection certainly raises a warning alarm when the learner rises into dangerous zones during the training. The evaluated safety assessments showed that our designed New OJT training level 1 course performed more efficient safety performance for self-training of the learner.     

Streptomyces phospholipase D mutants with altered substrate specificity capable of phosphatidylinositol synthesis

The substrate specificity of a phospholipase D (PLD) from Streptomyces antibioticus was altered by site-directed saturation mutagenesis, so that it was able to synthesize phosphatidylinositol (PI). Mutations were introduced in the pld gene at the positions corresponding to three amino acid residues that might be involved in substrate recognition, and the mutated genes were expressed in Escherichia coli BL21 (DE3). High-throughput screening of approximately 10,000 colonies for PI-synthesizing activity identified 25 PI-synthesizing mutant PLDs. One of these mutant enzymes was chosen for further analysis. The structure of the PI synthesized with the mutant enzyme was analyzed by HPLC-MS and NMR. It was found that the mutant enzyme generated a mixture of structural isomers of PIs with the phosphatidyl groups connected at different positions of the inositol ring. The phosphatidylcholine-hydrolyzing activity of the mutant PLD was much lower than that of the wild-type enzyme. The mutant enzyme was able to transphosphatidylate various cyclohexanols with a preference for bulkier compounds. This is the first example of alteration of the substrate specificity of PLD and of PI synthesis by Streptomyces PLD.     

Analysis of imidocarb in livestock and seafood products using LC-MS/MS

A simple method using high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was investigated for the detection of the antiprotozoal drug imidocarb in 10 livestock and seafood products. Liquid chromatographic separation employed a TSK VMpak-25 column with ammonium acetate-acetonitrile as a mobile phase. Mass spectral acquisition was performed in the ESI positive-ion mode. Imidocarb was extracted from all samples using liquid extraction with acetonitrile under basic conditions. For samples other than honey, fat-soluble impurities were removed by acetonitrile-hexane partitioning. The salting-out technique was used for extraction from honey in order to improve the separation of the organic solvent and water added to the honey sample. The limit of quantitation was 0.005 μg/g (expressed as concentration in samples). The recoveries from all samples were 76-109%, and the repeatability and reproducibility were also satisfactory.     

Antagonistic effect of the Ainu-selected traditional beneficial plants on the transformation of an aryl hydrocarbon receptor

Transformation of an aryl hydrocarbon receptor (AhR) is the initial step to express the multiple toxicity of halogenated and polycyclic aromatic hydrocarbons (HAHs and PAHs) including dioxins. Therefore, it has been suggested that suppression of the transformation induced by HAHs and PAHs leads to reduce their toxicological effects. In this study, the antagonistic effect of 110 indigenous plants (192 plant parts) used as medicine and/or food by the Ainu on the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced AhR transformation was investigated. Of these, a stalk of Aralia elata (Miq.) Seemann and a bark of Fraxinus mandshurica Rupr. var. japonica Maxim. exhibited the strong antagonistic effect in a dose-dependent manner. An antioxidative activity and polyphenol content were also measured, and the strong correlation (r= 0.96) between these two parameters could be confirmed. However, correlation coefficients of the antagonistic effect of 192 extracts compared to their antioxidative activity and polyphenol content were 0.17 and 0.20, respectively. These results suggest that the Ainu-selected traditional beneficial plants are useful source for findings of novel AhR antagonists, and the antagonistic activity of these plants may be independent on their antioxidative activity and polyphenol content. PRACTICAL APPLICATION: Our findings lead to discovery of the valuable plants used by the Ainu and the novel active compounds useful for human's life, and furthermore, may contribute to the development of new medicines and functional foods.     

CO2-facilitated transport membranes prepared by blending polyvinyl alcohol and various water-absorbing agents

This study describes the production of a membrane by blending polyvinyl alcohol (PVA) and water-absorbing agents for the selective permeation of CO₂ by optimizing the type of water-absorbing agent and its ratio to PVA. A CO₂-facilitated transport membrane is prepared by adding an aqueous cesium carbonate solution to a coated polymer blend matrix. When sodium polyacrylate (PAANa) is blended with PVA as a water-absorbing agent, the resulting membrane shows promising heat and pressure resistances and a relatively high CO₂/He separation performance. Particularly, the CO₂/He selectivity of the membrane composed of PVA, PAANa, and another water-absorbing agent exceeds 400 under a total pressure of 0.1 MPa and a CO₂ partial pressure of 0.08 MPa at 85°C. Moreover, the CO₂/He selectivity is approximately 100 even under a total pressure of 0.7 MPa and a CO₂ partial pressure of 0.56 MPa. Thus, a high-performance CO₂ separation membrane at 85°C is produced.