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This paper describes the state of the art of structural steel reuse in Japan. A significant part of the material is taken from a document titled the Architectural Institute of Japan (AIJ) Recommendations for Sustainable Steel Building Construction (Draft) available only in the Japanese language. The motivations for and potential benefits of steel reuse are examined. The affinity between seismic design requirements and steel reuse is highlighted through a concept known as damage-control design. Some technologies for disassembly are introduced. The historical development and changes in Japanese structural steel are summarized, followed by a discussion on reusability of historical steel reclaimed from existing buildings. Reuse projects whose details are known to the authors are listed. The heart of the paper is a design procedure that specifies the structural engineer's role and involvement in planning, material procurement, and executing a steel reuse project. The discussion is concluded by six directions that should be pursued to make steel reuse a widely accepted reality in Japan. Among those directions are research needs to establish a procedure to quantify the remaining structural performance of reclaimed steel considering possible exposure to earthquakes, establish connections that allow for easy disassembly, and introduce modularized structural systems. High seismicity and the general practice to adopt full moment frames pose unique challenges for steel reuse in Japan.

The authors have investigated the elastic-plastic behavior of the steel and concrete composite columns (SC column) and the beam-to-column connections composed SC columns and wide flange beams against severe earthquakes. The SC column is an octagonal sectional column composed of cross-shaped steel and concrete. A pulling experiment of connection for SC columns and steel flanges was carried out in order to make clear the difference of welded connection details on the behaviors of connection between a column flange and a beam flange with outer diaphragms and band-plates. The authors have performed FEM analysis and performed a comparison with the experiment behavior, and have made clear the difference of connection details on the behavior of frameworks quantitatively by performing numerical analysis. From these results, we will discuss the design method for beam-to-column connection composed of SC columns and wide flange beam where stress transmission mechanism is clear, and construction is simple.

The authors propose to develop a new structural column on steel-concrete (SC) composite structures. The main reason why cruciform steel used in the SC columns is selected is that concrete confined by cruciform steel has stronger than non-confined concrete. In this study, seven specimens were tested to investigate structural performance and the scale effect of concrete of large-scale the SC columns. The size of the cruciform steel and the presence of a shear connector are among the experimental variables considered. Based on the test results, the comparisons of the experimental results of the two types of specimens indicate that there was little the scale effect of concrete on the elastic-plastic behavior of SC columns. Furthermore, there is concern about a gap between steel and concrete due to drying shrinkage of concrete over time. A mechanical shear connector contributes stress transfer between steel and concrete. Mechanical shear connectors were welded to a web of the cruciform steel to ensure stress transfer. If a gap exists between steel and concrete due to drying shrinkage of concrete over time, the shear connector can transfer stress from steel to concrete.

Concrete-filled steel tube (CFST) columns are commonly used in Japan, which utilize onsite full-strength welded splices between columns. However, onsite welding requires high technical skill and a controlled environment. Further, this type of splice is expensive and, in most cases, is not necessary for dependable building performance under severe earthquake loading conditions. Recently, new types of CFST column splices have been developed that enhance constructability and avoid the need for onsite welding. In the proposed column splice method, perforated steel plates are placed on each column half and are welded into place. To evaluate the performance of this splice, it is important to determine the pull-out strength and behavior modes of the perforated steel plates embedded into the CFSTs. In this paper, a pull-out experiment with perforated steel plates embedded into a square CFST stub is conducted. The experimental parameters are the bond between the steel plate and the concrete, the embedded length of the perforation, and the extra length of the steel plate. The effect of the bond and friction strength between the steel and concrete are discussed, and a design formula for the pull-out strength of the perforated steel plate is examined.

SUMMARYStrongyloides venezuelensis is a parasitic nematode that infects rodents. Although Strongyloides species described to date are known to exhibit parthenogenetic reproduction in the parasitic stage of their life cycle and sexual reproduction in the free-living stage, we did not observe any free-living males in S. venezuelensis in our strain, suggesting that the nematode is likely to depend on parthenogenetic reproduction. We confirmed by cytological analysis that S. venezuelensis produces eggs by parthenogenesis during the parasitic stage of its life cycle. Phylogenetic analysis using nearly the full length of 18S and D3 region of 28S ribosomal RNA gene suggested that S. venezuelensis is distantly related to another rodent parasite, namely Strongyloides ratti, but more closely related to a ruminant parasite, Strongyloides papillosus. Karyotype analysis revealed S. venezuelensis reproduces with mitotic parthenogenesis, and has the same number of chromosomes as S. papillosus (2n = 4), but differs from S. ratti (2n = 6) in this regard. These results, taken together, suggest that S. venezuelensis evolved its parasitism for rodents independently from S. ratti and, therefore, is likely to have a different reproductive strategy.

The photon antibunching behavior in the photoluminescence (PL) of single CdSe/ZnS semiconductor nanocrystals (NCs) interacting with the localized surface plasmon resonance (LSPR) of Ag nanostructure was investigated using fs-pulsed laser excitation at two excitation wavelengths. The time traces of the PL intensity, the PL decay curves, and the photon correlations of single NCs on a rough Ag film and on a coverslip were measured simultaneously, and an increase in the PL intensity accompanied by shortening of the PL lifetime was observed for the single NCs on the rough Ag film. The enhancement factor of the PL intensity depended on the excitation wavelength. Nearly all of the single NCs with enhanced PL exhibited photon antibunching behavior independent of the enhancement factor. Based on the enhanced radiative- and nonradiative-decay rates estimated from the experimental data, the mechanism of the photon antibunching behavior was considered as follows. To exhibit the photon antibunching behavior, the nonradiative Auger recombination between the generated excitons in a single NC is important. When the radiative- and the nonradiative-decay rates enhanced by the LSPR are faster than the Auger recombination rate, the probability of photon antibunching decreases. However, such fast radiative- and the nonradiative decay rates were not observed for single NCs interacting with the LSPR of the rough Ag film in this work. Therefore, the PL intensity from a single NC can be increased while maintaining the photon antibunching behavior. Our findings assist in the creation of effective single-photon sources and provide important information on the emission properties of an NC coupled with the plasmon of a metal nanostructure.

This study evaluated the prevalence of Strongyloides stercoralis infection and human T-cell lymphotropic virus type 1 (HTLV-1) infection in the population. In addition, this study investigated the relationship between S. stercoralis infection or HTLV-1 infection and a patient's risk of developing related cancers. This is a retrospective cohort study of 5,209 patients. The prevalence of S. stercoralis infection was 5.2% among all patients. The prevalence among men (6.3%) was significantly higher than among women (3.6%, P < 0.001). The prevalence of HTLV-1 infection among this population was 13.6% and the prevalence among women (15.5%) was significantly higher than that of men (12.3%, P < 0.001). HTLV-1 seroprevalence was higher in patients with liver cancer (P = 0.003, odds ratio [OR]: 1.91, 95% confidence interval [CI]: 1.24, 2.95) and in those with lymphoma other than adult T-cell leukemia/lymphoma (ATLL) (P = 0.005, adjusted OR: 2.76, 95% CI: 1.36, 5.62) if compared with patients without any neoplasm. The prevalence of both S. stercoralis and HTLV-1 in the Okinawan population has been steadily decreasing over the past 24 years. HTLV-1 infection significantly increases the odds of developing liver cancer and lymphomas other than ATLL.