Changes in the thermomechanical behavior of epoxy glasses under the state of strain aging

Changes in thermomechanical behavior with structural relaxation taking place in epoxy glasses were studied. Differential scanning calorimetry measurements and thermostimulated strain recovery tests were performed for specimens deformed and then aged under fixed strain. In the course of heating, the specimens started to absorb thermal energy, whereas plastic strain was still stable. At higher temperatures, plastic strain started recovery, which was accompanied by exothermic behavior of the specimen. With an increase in the aging duration, the endothermic peak signified and moved to a higher temperature. These results indicated that the longer the aging duration was, the harder the plastic strain and strain energy were frozen in the glassy structure. This freeze‐strain phenomenon was observed for crosslinked epoxy glass, as well as polymeric glasses with linear molecular structures, aged under strain. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The diversification of proto-cells driven by membrane permselectivity

We consider how permselectivity as a function of the membrane is related to the cell evolution with an abstract proto-cell model. We construct an autopoietic proto-cell model having primitive auto-catalytic reaction cycle inside. In this model, several primitive membrane substances are assumed to be produced from the reaction cycle and the membrane is assumed to have a permeability to specific chemical species. We show that the permselectivity of the membrane induces the diversification of the cell volume. We discuss how the diversification of the cells is related to the Darwinian evolution. This work was presented in part and awarded as Young Author Award at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Framework for Performance-Based Design of Building Structures

Abstract:   This article proposes a new framework for performance-based design (PBD) of building structures. This framework was proposed under the 3-year Japanese Government Comprehensive Research and Development Project on "Development of a New Engineering Framework for Building Structures" launched in the fiscal year of 1995. The primary objective of the project is to create a system in which the performance of buildings is clearly stated, and consumers, that is, occupants, are well informed of how their buildings will perform and how much it will cost to maintain their performance. The framework emphasizes the establishment of target performance, the performance evaluation, and the performance statement as the main three elements. It also stresses that an institutional framework and support systems need to be provided to enable PBD to be practiced efficiently. The implementation of the proposed framework is also expected to promote engineering innovation, progress in building engineering, and globalization. The new framework will also bring other benefits, such as improved design techniques, greater design flexibility, and international harmonization. It is also important for building structural performance to become one of the most important indexes for consumers to define a building's value. The Japanese building code was changed to the performance-based code, based in the clear and comprehensive manner proposed in this article. In the United States, "Vision 2000" ( SEAOC, 1995 ) was published, then many research activities were conducted simultaneously.     

Role of ComFA in controlling the DNA uptake rate during transformation of competent Bacillus subtilis

The roles of ComFA and ComEC in DNA uptake by competent Bacillus subtilis were analyzed by transformation with DNA in protoplast lysates (LP transformation). Deletion mutants of comFA and comEC and putative Walker A mutants (K152N, K152Q, K152E) of comFA were constructed by fusion polymerase chain reaction. Transformants of comEC mutant with purified DNA and DNA in protoplast lysate were not obtained, which shows a lack of transformation ability and backwards recombination of the mutant. Transformants of the comFA mutant were obtained by LP transformation (1.8 × 10(4) transformants/μg DNA). Low relative efficiency of transformation (RET) of comFA compared to wild type (4.3 × 10(-4)) showed an important role for comFA in DNA uptake. Walker A mutants showed 1.8-19 × 10(-4) RET, suggesting a dependence on ATPase activity for transformation. Co-transformation between short linkages was only detected in comFA mutants. The results demonstrated that ComFA controlled the DNA uptake rate. The interpretation was further supported by analyzing the plasmid used in LP transformation of the comFA mutant. The RET of comFA compared to the wild type was 2.7 × 10(-2), 60-fold higher than that with chromosomal DNA (4.3 × 10(-4)). Following addition of DNA into comFA culture, transformants were obtained after 15 min, with the number of transformants increasing over time. The kinetics strongly suggested that in comFA mutants, formation of another DNA uptake complex without ComFA would be a lengthy process.     

α-gel prepared in sodium methyl stearoyl taurate/behenyl alcohol/water system-characterization of structural changes with water concentration

In this study, the changes in the structural and physicochemical properties of an α-crystalline phase (often called an "α-gel") were assessed in a sodium methyl stearoyl taurate (SMT)/behenyl alcohol/water system. The α-gels were characterized focusing on the effects of the alcohol/surfactant ratio and water concentration. Water molecules solubilized in the interlayer of the α-crystalline phase resulting in expanded interlayer spacing. Beyond the solubilization limit of 85 %, water molecules were trapped in the matrix of the α-crystalline phase in non-equilibrium (i.e., two phases). Accordingly, different self-diffusion coefficients for the solubilized and trapped water molecules were measured using a Fourier transform pulsed gradient spin echo technique to monitor the 1H NMR spectra. It was concluded that the two self-diffusion coefficients correspond to the water solubilized in the interlayer, i.e., "slow water," and trapped in the matrix of the α-crystalline phase, i.e., "fast water."     

Role of ComEA in DNA uptake during transformation of competent Bacillus subtilis

The role of the competence protein ComEA in DNA uptake during transformation of competent Bacillus subtilis was analyzed by lysed-protoplast transformation (LP transformation). A comEA deletion mutant was constructed by a fusion polymerase chain reaction. Transformants of the mutant were obtained by LP transformation at a frequency of 1.1 × 10(2) transformants per μg DNA, representing a low relative efficiency of transformation [RET (mutant/wild type)] of 2.7 × 10(-6). This implied an important role of the protein during DNA uptake. When analyzing LP transformation of comEA with a plasmid (5.7 kb), a similar RET (mutant/wild type) of 5.6 × 10(-5) was obtained. Following addition of DNA into the comEA mutant culture, the number of transformants increased at a rate of 0.5 transformants/min, which was very low compared with the wild-type (6.9×10(4) transformants/min). However, even in the comEA mutant, DNA uptake began immediately after addition of DNA. Using co-transformation analysis of the comEA mutant, short linkages at distances of 2-156 kb could be detected, but not long linkages at distances of 671-1662 kb. Taken together, the results indicate that ComEA plays an important role in the transfer of transforming DNA into the DNA channel and in controlling the rate of DNA uptake.     

Induction of the 2B9 antigen/dipeptidyl peptidase IV/CD26 on human natural killer cells by IL-2, IL-12 or IL-15

Activation of human natural killer (NK) cells involves sequential events including cytokine production and induction of cell surface molecules, resulting in the enhancement of cytolytic activity. To delineate the activation process of NK cells, we generated murine monoclonal antibodies (mAbs) against YT, a human large granular lymphocyte/natural killer (LGL/NK) cell line. Among the mAbs reactive with YT cells, one mAb, termed 2B9, was noted because of the lack of reactivity with most of the human T- and B-cell lines tested. In fresh peripheral blood mononuclear cells (PBMC), however, the majority of cells expressing this antigen (Ag) were T cells but not CD16+ nor CD56+ NK cells. Since YT cells showed an activated phenotype expressing interleukin-2 (IL-2) receptor alpha chain, we examined whether 2B9 Ag could be induced on normal human peripheral blood NK cells by cytokines known to activate NK cells. The 2B9 Ag was induced on NK cells by IL-2, IL-12 or IL-15 while no induction was observed by interferon-gamma (IFN-gamma). Biochemical analysis showed that anti-2B9 mAb recognized a 115 kDa molecule in YT cells. A cDNA clone encoding the 2B9 Ag was isolated from a cDNA expression library of YT cells and its sequence was identical to CD26 cDNA although it was not of full length. Transient expression of the 2B9 cDNA on COS-7 cells revealed that this cDNA encodes the antigenic epitope(s) recognized by anti-2B9 mAb as well as Ta1, an anti-CD26 mAb. These results showed that the 2B9 Ag is identical to CD26, and demonstrated that CD26 is an activation antigen on CD16+ CD56+ NK cells inducible by IL-2, IL-12 or IL-15.     

Integrity degradation of UO2 pellets subjected to thermal shock

Thermal shock behavior of UO₂ pellets has been investigated by means of out-of-pile experiments and a theoretical analysis which particularly emphasized the porosity effect on the thermal shock damage. In the experiments, specimens of porosity range 0.05–0.15 were thermal-shocked by heating and then quenching in a water bath at various quenching temperature differences (ΔT). Results showed that with increasing porosity, ΔT values cause a first damage (ΔT_c) and bring about destructive failure of the specimens increased, while the strength loss at ΔT_c was reduced. These findings suggested that the higher the porosity, the higher the pellet integrity during rise to power. Theoretical equations expressing the thermal shock damage were introduced. Good agreements were obtained between observed and predicted values.     

Contents of D-lactate and its related metabolites as well as enzyme activities in the liver, muscle and blood plasma of aging rats

Regulatory elements within the promoter of the pollen-specific NTP303 gene from tobacco were analysed by transient and stable expression analyses. Analysis of precisely targeted mutations showed that the NTP303 promoter is not regulated by any of the previously described pollen-specific cis-regulatory elements. However, two adjacent regions from -103 to -86 bp and from -86 to -59 bp were shown to contain sequences which positively regulated the NTP303 promoter. Both of these regions were capable of driving pollen-specific expression from a heterologous promoter, independent of orientation and in an additive manner. The boundaries of the minimal, functional NTP303 promoter were determined to lie within the region -86 to -51 bp. The sequence AAATGA localized from -94 to -89 bp was identified as a novel cis-acting element, of which the TGA triplet was shown to comprise an active part. This element was shown to be completely conserved in the similarly regulated promoter of the Bp 10 gene from Brassica napus encoding a homologue of the NTP303 gene.     

Study on the compensation of error by stick-slip for high-precision table

A simple approach of compensating friction error of high-precision tables is proposed in this paper. On the basis of accurate prediction of the magnitude of the friction error and the place where it occurs, a compensator is first constructed which consists of an online friction error prediction model and rectangular compensation curves regarded as compensation pulses. Then by carrying out optimal compensation experiments several times, the parameters describing the rectangular compensation curve at certain positions can be obtained. Finally, the optimal parameters of the rectangular compensation curve at any position can be determined by interpolation and approximation. It has been shown that, the method to compensate friction error proposed in this paper can be applied to effectively compensate the friction error for all circular motions of high-precision tables.