Whale rover moving along the surface of sperm whale

ABSTRACT

Biologging, which uses small data loggers directly attached to the bodies of animals to collect various behavioral data, can be an effective means for revealing the mysteries of animal life. With respect to marine animals, zoologists have attempted to obtain video data of a sperm whale eating a giant squid using biologging. These previous efforts have been unsuccessful because the biologger, which was attached to the whale's back that emerged from the sea as the whale swam, provided poor visibility of the whale's mouth area in the deep sea. To solve this problem, we proposed a novel roving biologger or whale rover that travels along a sperm whale's body surface from its back to its mouth area using robotic technology. Four prior whale rover prototypes have been designed and developed. In this study, we further improved the whale rover design to allow for adapted travel on curved or uneven surfaces. The feasibility of this fifth prototype was confirmed using both field and laboratory experiments. These experimental results demonstrated the whale rover's ability to successfully travel across a flat surface at a depth of almost 500 m and across a curved surface in a laboratory water tank.     

Superior Alignment of Human iPSC-Osteoblasts Associated with Focal Adhesion Formation Stimulated by Oriented Collagen Scaffold

Human-induced pluripotent stem cells (hiPSCs) can be applied in patient-specific cell therapy to regenerate lost tissue or organ function. Anisotropic control of the structural organization in the newly generated bone matrix is pivotal for functional reconstruction during bone tissue regeneration. Recently, we revealed that hiPSC-derived osteoblasts (hiPSC-Obs) exhibit preferential alignment and organize in highly ordered bone matrices along a bone-mimetic collagen scaffold, indicating their critical role in regulating the unidirectional cellular arrangement, as well as the structural organization of regenerated bone tissue. However, it remains unclear how hiPSCs exhibit the cell properties required for oriented tissue construction. The present study aimed to characterize the properties of hiPSCs-Obs and those of their focal adhesions (FAs), which mediate the structural relationship between cells and the matrix. Our in vitro anisotropic cell culture system revealed the superior adhesion behavior of hiPSC-Obs, which exhibited accelerated cell proliferation and better cell alignment along the collagen axis compared to normal human osteoblasts. Notably, the oriented collagen scaffold stimulated FA formation along the scaffold collagen orientation. This is the first report of the superior cell adhesion behavior of hiPSC-Obs associated with the promotion of FA assembly along an anisotropic scaffold. These findings suggest a promising role for hiPSCs in enabling anisotropic bone microstructural regeneration.     

Improved antifouling of anion-exchange membrane by polydopamine coating in electrodialysis process

The fouling, in particular the organic fouling of anion exchange membranes (AEMs), is a serious problem in electrodialysis (ED). In this paper, we attempted to improve the antifouling potential of AEM by surface modification with polydopamine (PDA). The antifouling potential was evaluated by the transition time, i.e. the time elapsed before fouling took place, using sodium dodecyl benzene sulfonate (SDBS) as a model foulant. The negative surface charge density, hydrophilicity and roughness of the membrane surface were increased with increasing dopamine concentration in the modification solution. The increases in negative surface charge density and hydrophilicity increased the antifouling potential, while the increase in surface roughness decreased the antifouling potential. Consequently, the optimum modification condition was the immersion into a 0.1 kg/m³ dopamine aqueous solution at pH 8.8 for 24 h. Under this condition, the antifouling potential of AEM was sufficiently improved. It was shown by theoretical analysis of the fouling data that the surface modification with PDA prevented the adsorption of SDBS micelles and improved the antifouling potential. Furthermore, it was experimentally confirmed that the modified membrane was highly stable.     

Interfacial Reaction between Zn-Al-Based High-Temperature Solders and Ni Substrate

The Zn-Al(-Cu) eutectic alloys (melting point 381°C) are candidates for use as Pb-free high-temperature solders as a substitute for Pb-based solders, which are suitable for severe working environments such as the engine room of hybrid vehicles equipped with an inverter system as well as a heat engine. In this study, the interfacial reaction between Zn-Al(-Cu) alloys and the Ni substrate during soldering, aging, and thermal cycling was investigated. Semiconductor chips and Ni substrates were soldered with Zn-Al(-Cu) alloys at various temperatures under a nitrogen atmosphere. The soldered assemblies were then heat-treated at 200°C and 300°C to examine the microstructural evolution at the soldered interface. The effect of severe thermal cycles between −40°C and 250°C in air on the microstructure and fracture behavior at the solder joint was investigated. Even after a 1000-cycle test, the thickness of the Al₃Ni₂ layer formed at the interface between the Zn-Al-based solder and the Ni substrate, which is responsible for the damage of the soldered assemblies, was quite small.     

Quasi-damascene metal gate/high-k CMOS using oxygenation through gate electrodes

We present a novel metal gate/high-k complementary metal–oxide–semiconductor (CMOS) integration scheme with symmetric and low threshold voltage (V_th) for both n-channel (nMOSFET) and p-channel (pMOSFET) metal–oxide–semiconductor field-effect transistors. The workfunction of pMOSFET is modulated by oxygen in-diffusion (‘oxygenation’) through the titanium nitride metal gate without equivalent oxide thickness (EOT) degradation. A significant V_th improvement by 420 mV and an aggressively scaled capacitance equivalent thickness under channel inversion (T_inv) of 1.3 nm is achieved for the pFET by using a replacement process in conjunction with optimized oxygenation process. Immunity of nMOSFET against oxygenation process is demonstrated.     

Effect of physicochemical structure of natural fiber on transverse thermal conductivity of unidirectional abaca/bamboo fiber composites

To study the effect of the microstructure of natural fiber on the transverse thermal conductivity of unidirectional composite, abaca and bamboo fibers were unidirectionally aligned to fabricate epoxy composites by a resin transfer molding (RTM) technique. The transverse thermal conductivity of these two types of composites was measured in a steady-state platform. X-ray diffractometer and scanning electron microscopy were applied to analyze the microstructure and morphology of both fibers and composites. The results indicated that the transverse thermal conductivity showed two types of tendencies with fiber content increasing: increasing for bamboo fiber composites, and decreasing for abaca fiber composites. The microstructure and theoretical analysis suggest that the lumen structure plays a great role rather than crystal structures and chemical compounds on the transverse thermal conductivity of unidirectional composites, which is useful for further development and design of natural fiber reinforced composites with better thermal insulation property for people’s daily life.     

Continuously Frequency Tunable High Power Sub-THz Radiation Source—Gyrotron FU CW VI for 600 MHz DNP-NMR Spectroscopy

A high frequency gyrotron with a 15 T superconducting magnet named Gyrotron FU CW VI has achieved continuous frequency tuning through the relatively wide range of 1.5 GHz near 400 GHz. The operation is at the fundamental cyclotron resonance of the TE₀₆ cavity mode with many higher order axial modes. The output power measured at the end of the circular waveguide system ranges from 10 to 50 watts at the low acceleration voltage of 12 kV for beam electrons. The beam current is also low. It is around 250 mA. This gyrotron is designed as a demountable radiation source for the 600 MHz DNP-NMR spectroscopy. The design and operation results of the gyrotron FU CW VI are presented.     

Isolation and characterization of murine hepatocytes following collagenase infusion into left ventricle of heart

A method for obtaining mouse hepatocytes by infusing collagenase solution into the left ventricle was established. This technique was shown to be equivalent to the intra-portal infusion method and more practical, especially in postnatal mice with a small body size.