SUMMARYThe Active Variable Stiffness (AVS) system is proposed as a seismic response control system. It actively controls structural characteristics, such as stiffness of a building, to establish a non-resonant state against earthquake excitations, thus suppressing the building's response. It consumes a relatively small amount of energy and maintains the safety of the building in moderate to severe earthquakes. In order to accumulate practical data and investigate them, a building has been constructed as a trial. This paper describes the applied system, the control algorithm, verification of stiffness selection, results of tests for verifying system characteristics, some observed earthquake records and simulation analyses. Responses in controlled and uncontrolled states have been compared to show the effectiveness of the proposed system.

SUMMARYThis paper presents the "rst application of a semi-active damper system to an actual building. The Semi-active Hydraulic Damper (SHD) can produce a maximum damping force of 1000 kN with an electric power of 70 W. It is compact, so a large number of them can be installed in a single building. It is thus possible to control the building's response during a severe earthquake, because a large control force is obtained in comparison with a conventional active control system. This paper outlines the building, the control system con"guration, the SHD, the control method using a Linear Quadratic Regulator, the response analysis results of the controlled building, and the dynamic loading test results of the actual SHD. The simulation analysis shows that damage to building can be prevented in a severe earthquake by SHD control. The dynamic loading test results of the SHD are reported, which show that the speci"ed design values were obtained in the basic characteristic test. The control performance test using simulated response time histories, also shows that the damping force agrees well with the command. Finally, it is con"rmed that the semi-active damper system applied to an actual building e!ectively controls its response in severe earthquakes.

SUMMARYAn Active Mass Driver (AMD) system is proposed to suppress actively the response of a building to irregular external excitations such as earthquakes and typhoons. This system has been introduced to an actual ten-storey office building for the first time in the world. The system controls the motions of a structure by means of an external energy supply. It consists of an auxiliary mass installed in a building and an actuator that operates the mass and produces a control force which counters disturbances to the building. The design method of the AMD system, including the location of the installation and the capacity and stability of the system, is proposed. Simplification of the control algorithm is also described.

In recent years, green syntheses have been researched comprehensively to develop inexpensive and eco-friendly approaches for the generation of nanoparticles. In this context, plant and microbial sources are being examined to discover potential reducing agents. This study aims to utilize an extracellular pigment produced by Talaromyces purpurogenus as a prospective reducing agent to synthesize silver nanoparticles (AgNPs). Biosynthesized AgNPs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), electron probe micro analyser (EPMA), and zeta potential. The pigment functional groups involved in the generation of AgNPs were investigated using Fourier transform infrared spectroscopy. TEM images showed that the generated nanoparticles were spherical, hexagonal, rod-shaped, and triangular-shaped with a particle size distribution from 4 to 41 nm and exhibited a surface plasmon resonance at around 410 nm. DLS and zeta potential studies revealed that the particles were polydispersed and stable (−24.8 mV). EPMA confirmed the presence of elemental silver in the samples. Biosynthesized AgNPs exhibited minimum inhibitory concentrations of 32 and 4 μg/mL against E. coli and S. epidermidis, respectively. Further, cytotoxicity of the AgNPs was investigated against human cervical cancer (HeLa), human liver cancer (HepG2), and human embryonic kidney (HEK-293) cell lines using 5-fluorouracil as a positive control. A significant activity was recorded against HepG2 cell line with a half-maximal inhibitory concentration of 11.1 μg/mL.

A new control strategy to improve a tuned mass damper (TMD) is disturbances. The feedback gain of the proposed algorithm is linear to the response acceleration of the primal system and it is optimized in :he frequency domain under a harmonic excitation. According to this method both the feedback gain and the TMD parameters are optimized in the frequency domain and they are expressed in a set of closed form solutions. The performance of the proposed control method is discussed and compared with that of a passive TMO.

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The proper function of the genome largely depends on the higher order architecture of the chromosome. Our previous application of nanotechnology to the questions regarding the structural basis for such macromolecular dynamics has shown that the higher order architecture of the Escherichia coli genome (nucleoid) is achieved via several steps of DNA folding (Kim et al., 2004). In this study, the hierarchy of genome organization was compared among E. coli, Staphylococcus aureus and Clostridium perfringens. A one-molecule-imaging technique, atomic force microscopy (AFM), was applied to the E. coli cells on a cover glass that were successively treated with a detergent, and demonstrated that the nucleoids consist of a fundamental fibrous structure with a diameter of 80 nm that was further dissected into a 40-nm fiber. An application of this on-substrate procedure to the S. aureus and the C. perfringens nucleoids revealed that they also possessed the 40- and 80-nm fibers that were sustainable in the mild detergent solution. The E. coli nucleoid dynamically changed its structure during cell growth; the 80-nm fibers releasable from the cell could be transformed into a tightly packed state depending upon the expression of Dps. However, the S. aureus and the C. perfringens nucleoids never underwent such tight compaction when they reached stationary phase. Bioinformatic analysis suggested that this was possibly due to the lack of a nucleoid protein, Dps, in both species. AFM analysis revealed that both the mitotic chromosome and the interphase chromatin of human cells were also composed of 80-nm fibers. Taking all together, we propose a structural model of the bacterial nucleoid in which a fundamental mechanism of chromosome packing is common in both prokaryotes and eukaryotes.

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