The present status about recycling of minor rare metals and rare-earth elements was briefly summarized. We should understand that the recycling of minor rare metals and rare earth elements is mainly supported by the establishments of a social system and solid separation and chemical refining technologies and pure science partially contributes to the establishments of chemical refining technologies. The solid separation technologies are particularly important in the recycling, and it is necessary to establish the essential theory of this field. Here the results of a national project on the recycling of small domestic appliances implemented by us and the dismantling of a hybrid car motor as shown. It is very essential to understand that the recycling technology begins in here, although it is very unrefined technically. Establishing the supply chains of minor rare metals and rare -earth elements in our society is one of the key issues in considering the industry structure of our country to achieve a true circulatory society in the future.

Biomass is a renewable carbon neutral resource, because it can fix carbon dioxide from the atmosphere by photosynthesis. Recently, it has attracted more attention as an alternative fuel resource from the viewpoints of global warming mitigation and fossil resource saving. However, in Japan, biomass resources are very limited and have a low energy for their sustainable production and utilization. Therefore, a more intensive and focused research and development is required to convert biomass into energy at a higher efficiency. In addition, the gasification technology of biomass has been considered for the establishment of a renewable hydrogen society. The Biomass Technology Research Center (BTRC) of AIST has been conducting technical developments and organizing a social system for biomass utilization to establish a sustainable society not only in Japan but also in other countries in terms of the following three important targets：1) ethanol production from woody biomass; 2) biomass-to-liquid(BTL) process, and 3) study on the biomass total system. On the basis of the obtained results, a sustainable biomass-refining coproduction system should be developed for the establishment of a future low-carbon society.

High-efficiency electric power conversion is an important technology for energy saving. Silicon carbide (SiC) power devices exhibit a high blocking voltage, a low on-resistance, and a high switching speed, owing to its superior physical properties. Through recent progress in SiC growth and device technologies, SiC Schottky barrier diodes and power MOSFETs are now commercially available, contributing to the development of high-efficiency and compact power conversion systems. In this report, progress and remaining issues of the SiC material as well as power devices are reviewed.

“Life-Cycle Analysis” is an effective methodology for evaluating the environmental characteristics of production and service activities. In this paper, examples and guidelines for the life cycle analysis of photovoltaic power generation system, which is one of the most environmental friendly technologies, are presented. Also, perspectives on the life cycle analysis of photovoltaic technology are described.

Thermophotovoltaic (TPV) systems offer a unique, solid-state approach to converting heat into electricity based on thermal radiation. TPV is particularly suitable for certain classes of problems that are difficult for standard engines, such as long, remote missions where repairs are difficult, and portable generation where space and weight are at a premium. While standard thermophotovoltaics are limited in their conversion efficiency, photonic crystals can improve performance by an order of magnitude for a number of systems. Finally, two exemplary systems are discussed : TPV μreactors for portable power generation in a mm-scale form factor, and solar TPV for long-term off-grid power generation from sunlight. In both cases, photonic crystals can enable an order of magnitude enhancement in performance, implying potential performance exceeding that of many other well-known technologies, such as single-junction photovoltaics.

Although our energy strategy should be reconsidered in the future, the distributed power generation and more efficient use of fossil fuels are desired, in addition to renewable energies. In this contribution, the current status of hydrogen energy based on fuel cell technologies is reviewed as an alternative promising energy technology. Materials research and device engineering related to applied physics are also explained.

On-site monitoring for precise control is being expected in the agriculture and animal industry. For living up to the expectation, a multimodal sensor integrating several types of sensors that are capable of measureing factors effecting the target is required. We fabricated a multimodal sensor integrated with a pH, an electrical conductivity and temperature sensors. Because solutions in the soil and stomach can electrify, the multimodal sensor had cross talk between the pH and electrical conductivity sensors. Therefore, sensor operating methods and an output signal processing system were reformed. Real time and simultaneous measurements using the multimodal sensor were successful. On the other hand, a wireless unit with wireless modules and the multimodal sensor was fabricated. The wireless unit was successful in the wireless and real time measurements of the stomach juice of a cow.

Nano-photocatalytic materials have shown great potential not only in environmental remediation but also in solar-chemical conversion by photocatalytic water splitting as well as CO₂ reduction. However, there remains a great challenge in developing highly sensitive photocatalytic materials in the visible light region. Recently, we have reported that Ag₃PO₄, an inorganic material, exhibits a high quantum efficiency approaching that of a photosynthetic process for water oxidation. The possible origin of the superhigh photooxidative property and its potential will be introduced in this article.

Lightning damage of blades is the most serious problem in wind turbine generators. The mechanism and cause of such damage are investigated by lightning observation and high-voltage and large-current experiments. Lightning damage of the blade of a wind turbine still remains a problem even if receptors and a down conductor are installed. A new development for better protection measures of blades, including not only a better form and layout of receptors but also independent lightning towers and new materials for blades, is necessary.

It is possible to classify Funaria hygrometrica as an r-strategy species characterized by a growth pattern with an exponential phase in our suspension culture system. The practical metal mining method using dry powder of this species is generally classified as a carbon neutral process. We used this method to check the quality of various product cells as lead absorbents. Most product cells could be sufficient lead absorbents. Thus, we proposed the employment of protonemal cells produced by a large-scaled culture system to remove lead from an aqueous solution.

Bloch states in crystals are introduced in terms of k-space and Brillouin zone. The expressions for velocity and effective mass are given by using the wave packets of Bloch states.