Nanofiber networks of two or three dimensions are promising materials for flexible devices, and electrospinning is a straightforward method for forming the nanofibers. Using chemical vapor deposition, we fabricated carbon nanotube field emitter arrays on a substrate of electrospun carbon fabric composed of thin carbon fiber. That fabric serves as a suitable substrate because it offers high thermal stability, electrical conductivity, and flexibility. Our hierarchy-structured carbon emitter exhibited better field-emission properties than carbon nanotubes fabricated on a silicon substrate. We carried out our work in cooperation with a group led by Professor Gehan Amaratunga at the University of Cambridge.

Members of the Tanioka Laboratory are exploring applications for nanofibers in bioengineering, information technology, environmental catalytic systems, and fuel cells. Work in the laboratory also includes research on the fluorescence quenching of organic materials, advanced materials for water purification, electrolysis, and the diffusion and sorption of gas across polymer membranes.

Acute myocardial infarction is a frequent cause of chronic heart failure and is especially common in the industrialized nations. About 1.5 million individuals in the United States suffer acute myocardial infarction annually. We have found that the molecule periostin performs an essential function in repairing disrupted heart tissue after infarction.

The recruitment of fibroblastic cells to the infarct is essential to the cardiac healing process. Researchers have associated stiffness of the extracellular matrix in the infarcted myocardium with cardiac healing, but the molecular mechanism of cardiac healing remains unclear.

Periostin, we have shown, acts to recruit the cells that repair the defective cardiac muscle. We developed periostin-null mice and verified that the cardiac healing after acute myocardial infarction was conspicuously slower in those mice than in otherwise normal mice. Those and related findings that we have reported highlight the importance of activating periostin to promote cardiac healing after acute myocardial infarction.

Maintaining liquid droplets in a vacuum at high temperature could be useful in processes for forming new ceramics, such as liquid-assisted crystal growth. Liquid droplets in a vacuum ordinarily evaporate, however, on heating. A possible means of preventing that evaporation is the classical surfactant effect.

We employed the surfactant effect in stabilizing the high-temperature molten salt of ceramics in a vacuum. Real-time imaging with a laser microscope revealed that adding CuOx to Bi₂O₃ as a surfactant stabilized the ceramic liquid droplets.

The imaging of ceramic droplets is part of work in the Matsumoto Laboratory on vacuum processing for nanomaterials. Members of the laboratory also study oxide hetero nanoelectrodes, new nanostructures based on oxide surface chemistry, and on new oxide devices controllable with chemical reactions.

Innovative reprocessing methods for the spent fuels of fast breeder reactors are an important development issue in the nuclear fuel cycle. We have found that N-cyclohexyl-2-pyrrolidone can selectively precipitate UO₂²⁺ in an HNO₃ aqueous solution, and we have developed a reprocessing process that uses pyrrolidone derivatives (NRP) as precipitants. Our process first precipitates U(VI) species with precipitants of low hydrophobicity and donicity and then precipitates U(VI) and Pu species with precipitants of high hydrophobicity and donicity.

We examined the effectiveness of different precipitants for UO₂²⁺ in HNO₃, and we analyzed the crystal structures of UO₂(NO₃)₂(NRP)₂. Our finding was that packing efficiency is an important factor in precipitation ability and that we can estimate that efficiency in reference to a compactness parameter defined as the mean volume occupied by one C atom of the alkyl chain in a UO₂(NO₃)₂(NRP)₂ crystal.

The Uzawa-Lucas model of economic growth is the only basic two-sector endogenous growth model developed thus far and is of great methodological importance. It is technically difficult to use, however, because of its complicated transitional dynamics. We have formulated a two-sector endogenous growth model that features intersectoral knowledge spillovers, and we have associated local dynamics with the slope of the excess demand curve for a consumption good.

Our model exhibits the unique steady state and no transitional dynamics if and only if the excess demand curve slopes downward. The model, because of its simple dynamics, is applicable to several fields, such as international economics and public economics.