Ytterbium-decreasing Streptomyces sp. and its naphthoquinone-pigment production in the presence of rare-earth elements

We screened for oligotrophic microorganisms capable of decreasing the concentration of ytterbium (Yb), a representative of the heavy rare-earth elements, in a culture medium. From 476 strains of oligotrophic microorganisms (grown on 1/100 diluted nutrient agar) isolated from soil and river water samples, 5 strains capable of reducing the concentration of Yb in diluted nutrient broth containing 5 ppm Yb were selected. Among them, a strain capable of reducing the concentration of all rare-earth elements to a great extent was identified as Streptomyces sp. (strain YB-1). This strain produced redish-purple pigment(s) only in the presence of rare earths, but not in that of other metals. The pigment was extracted with ethyl acetate and purified by a series of column chromatography steps. From the results of structural analysis using ultraviolet or infrared absorption spectrometry and 13C-NMR, the pigment was determined to be a kind of naphthoquinone similar to nanaomycin produced by a Streptomyces sp. These results suggested that rare earths might affect the physiological activity of this strain.     

Fluorescent in situ hybridization in combination with filter cultivation (FISHFC) method for specific detection and enumeration of viable Clostridium perfringens

To reduce time for enumeration of viable Clostridium perfringens, fluorescence in situ hybridization in combination with filter cultivation (FISHFC) was employed. The method utilized a CLP-180 probe, based on the 16S rRNA region of C. perfringens, and FISHFC fluorescence microscopy to detect C. perfringens, but not organisms from other species. Optimal cultivation requirements for micro-colony formation were TSC medium, anaerobic conditions, 37 °C, and incubation for 6 h. Under these conditions, micro-colony diameters reached 100 μm, a size sufficient for hybridization. Enumeration of C. perfringens using the CLP-180-aided FISHFC method was realized in 9 h as compared to 3–5 days required by the conventional plate count method. Moreover, viable C. perfringens counts of food samples from the two methods were not significantly different.     

Preservative effect of combined treatment with electrolyzed NaCl solutions and essential oil compounds on carp fillets during convectional air-drying

The antimicrobial and antioxidant effects on carp fillet samples of treatments with alkaline electrolyzed NaCl solution EW (-) prior to treatment with acidic electrolyzed NaCl solution EW (+) and 1% solutions of the essential oils consisting of 0.5% carvacrol and 0.5% thymol (1% Cv+Ty) were tested. First carp fillet samples were treated with EW (-), then EW (+), followed by 1% (C+T), represented as [EW (-)/EW (+)/1% (Cv+Ty)] for 15 min, during drying at 45 degrees C. Samples were subsequently evaluated by microbiological, chemical and sensory analyses. Microbiological analyses indicated that the initial total microbial counts of samples treated with EW (-)/EW (+), 1% (Cv+Ty) or EW (-)/EW (+)/1% (Cv+Ty) were significantly (p< or =0.05) reduced, compared with the control sample. Treatment with EW (-)/EW (+)/1% (Cv+Ty) gave the strongest overall inhibition of microbial growth when compared to all of the other treatments. The volatile basic nitrogen (VBN) value of samples treated with EW (-)/EW (+)/1% (Cv+Ty) was kept at low level (18.46+/-0.45) until the end of drying period (5 days), compared with control samples (40.33+/-0.58). Treatment with EW (-)/EW (+)/1% (Cv+Ty) during drying significantly reduced the peroxide values (PV) and thiobarbituric acid values (TBA). Sensory evaluation indicated that there were significant differences (p< or =0.05) in the color, odor, taste, flavor and texture, on the end of the 5-day drying period between samples treated with EW (-)/EW (+)/1% (Cv+Ty), as compared to all of the other treatments. We conclude that treatment with EW (-)/EW (+)/1% (Cv+Ty) had stronger antimicrobial and antioxidant effects than all of the other treatments on carp fillets during drying, and could be a good alternative to artificial preservatives in food industry.     

Parallel BDD-based monolithic approach for acoustic fluid-structure interaction

Parallel BDD-based monolithic algorithms for acoustic fluid-structure interaction problems are developed. In a previous study, two schemes, NN-I + CGC-FULL and NN-I + CGC-DIAG, have been proven to be efficient among several BDD-type schemes for one processor. Thus, the parallelization of these schemes is discussed in the present study. These BDD-type schemes consist of the operations of the Schur complement matrix-vector (Sv) product, Neumann-Neumann (NN) preconditioning, and the coarse problem. In the present study, the Sv product and NN preconditioning are parallelized for both schemes, and the parallel implementation of the solid and fluid parts of the coarse problem is considered for NN-I + CGC-DIAG. The results of numerical experiments indicate that both schemes exhibit performances that are almost as good as those of single solid and fluid analyses in the Sv product and NN preconditioning. Moreover, NN-I + CGC-DIAG appears to become more efficient as the problem size becomes large due to the parallel calculation of the coarse problem.     

A general method for predicting temperature-dependent anisomorphic constant fatigue life diagram for a woven fabric carbon/epoxy laminate

The anisomorphic constant fatigue life (CFL) diagram approach to prediction of fatigue lives of composites, which was developed in an earlier study, is developed further into a more general methodology that can deal with the mean stress sensitivity in fatigue of composites at different temperatures. The temperature dependence of the anisomorphic CFL diagram for a given composite is characterized by the temperature dependence of the static strengths in tension and compression and of the reference S–N relationship for a critical stress ratio. The temperature dependence of the static strengths in tension and compression is first formulated to describe the temperature dependence of the critical stress ratio. To predict the reference S–N relationships at different temperatures, the change in the value of critical stress ratio with temperature as well as the effect of temperature on fatigue should be taken into account. To this end, a new and efficient engineering method is developed which is based on a grand master S–N curve built by means of a modified fatigue strength ratio and a life-temperature parameter of the Larson–Miller type. The generalized anisomorphic CFL diagram approach developed in this study succeeds in efficiently and adequately predicting the CFL diagrams for a woven fabric carbon/epoxy quasi-isotropic laminate at different temperatures and thus the mean stress dependence of the S–N relationships of the laminate at different temperatures.     

A three-segment anisomorphic constant life diagram for the fatigue of symmetric angle-ply carbon/epoxy laminates at room temperature

The anisomorphic constant fatigue life (CFL) diagram approach that was developed in an earlier study is further tested for applicability to the matrix-dominated fatigue failure in symmetric angle-ply carbon/epoxy laminates. An extension of the CFL diagram approach is also attempted to improve the accuracy of fatigue life prediction. The original anisomorphic CFL diagram approach can be used for approximately predicting the CFL diagrams for the [±30]_3S and [±45]_3S laminates, while it fails to accurately predict the CFL diagram for the [±60]_3S laminate due to its significant local distortion. For accommodating the anisomorphic CFL diagram approach to the local distortion in CFL curves due to a significant change in mean stress sensitivity in fatigue, a transitional segment is inserted between the tension–tension and compression–compression dominated segments. It is demonstrated that the three-segment anisomorphic CFL diagram approach allows improved predictions of the CFL diagrams and S–N relationships for the angle-ply laminates.     

Optimizing process allocation of parallel programs for heterogeneous clusters

The performance of a conventional parallel application is often degraded by load‐imbalance on heterogeneous clusters. Although it is simple to invoke multiple processes on fast processing elements to alleviate load‐imbalance, the optimal process allocation is not obvious. Kishimoto and Ichikawa presented performance models for high‐performance Linpack (HPL), with which the sub‐optimal configurations of heterogeneous clusters were actually estimated. Their results on HPL are encouraging, whereas their approach is not yet verified with other applications. This study presents some enhancements of Kishimoto's scheme, which are evaluated with four typical scientific applications: computational fluid dynamics (CFD), finite‐element method (FEM), HPL (linear algebraic system), and fast Fourier transform (FFT). According to our experiments, our new models (NP‐T models) are superior to Kishimoto's models, particularly when the non‐negative least squares method is used for parameter extraction. The average errors of the derived models were 0.2% for the CFD benchmark, 2% for the FEM benchmark, 1% for HPL, and 28% for the FFT benchmark. This study also emphasizes the importance of predictability in clusters, listing practical examples derived from our study. Copyright © 2008 John Wiley & Sons, Ltd.     

Preparation and characterization of Maillard reacted chitosan films with hemicellulose model compounds

The Maillard reaction between chitosan and hemicellulose model compounds such as mannose, xylose, and glucuronic acid was investigated. Chitosan and the compounds were dissolved in 1% acetic acid and were dried at 50°C. In an analysis of the film obtained, weight increase, color difference, FTIR, relative amount of free amino groups, insolubility to dilute acetic acid, and tensile properties were measured. The film weight increased gradually as the compounds were added, and the color difference changed significantly. In addition, the relative amount of free amino groups decreased rapidly, and the insoluble matter increased markedly. In particular, xylose brought about drastic changes in a small amount addition. According to the results of FTIR spectra, the cleavage of sugar unit of chitosan and the formation of heterocyclic compounds were observed in all compounds. The formation of carbonyl and carboxyl groups was observed with the addition of a large amount of the compounds. The tensile strength was improved in 10–20 wt % additions of the compounds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Near-infrared luminescent polymer thin films containing Yb(III) complex and photosensitized dye

Polymethylmethacrylate (PMMA) thin films containing Yb(pms)₃(H₂O)₈ (pms: bis(perfluoromethanesulfonyl)imide) and dipyridophenazine with DMSO and DMSO-d₆ were fabricated on the glass substrates. The films show photosensitized near-IR luminescence under UV light irradiation of 370 nm in wavelength. The emission quantum yields of Yb(III) complex in PMMA (film 1), PMMA containing DMSO (film 2), and PMMA containing DMSO-d₆ (film 3) thin films are 0.18, 0.26, and 0.26%, respectively. The emission quantum yields of films 1 and 2 were considerably enhanced after the annealing at 80 °C.