• Plasma sterilization has been developed as an alternative sterilization method due to its chemical activity, operation at low temperature and atmospheric pressure, low power consumption, low cost and safety. We have studied a mechanism of chemical species generation and transport in a plasma flow and, the sterilization efficacy and mechanism for several plasma sources at atmospheric pressure, such as a microwave plasma flow, a dielectric barrier discharge in a tube and a water vapor plasma flow. We already clarified that the damages of outer membrane and destructions of the cytoplasmic membrane of Escherichia coli by exposure to the microwave plasma flow. Fig. 1 shows the effect of plasma exposure on the E. coli. When the E. coli was exposed to the plasma, the height of the E. coli decreased and the potassium leakage of cytoplasmic material increased. For sterilization in a tube, we also clarified that an induced flow in the narrow tube by DBD transports chemical species and sterilize the whole inside surface of a tube as shown in Fig. 2. We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

• Microwave processing is one of the attractive fields in recent materials processing. We perform various materials processing using non-equilibrium reaction field induced by microwave and/or ultrasonic irradiation. The topic contains powder metallurgy, nitride coatings, synthesis of new functional materials, fabrication of nanoparticles, etc. Recently we have developed a new TiN coating method using our microwave irradiation equipment operated at a frequency of 2.45 GHz. The method is simple but applicable to various substrates with complex shape. This method can be applied to various nitride coatings and will open a new coating technology in many fields of applications.

The major targets of TiN coatings are for cutting tools, ball bearings, dental implants, die and mold for stamping, and ornaments. The newly developed method makes it possible to perform nitride coatings within a short time using a standard microwave heating equipment. We hope to conduct collaborative research with a willing company for a practical application of these technology.

• We found an effective catalyst system composed of CeO2 and 2-cyanopyridine for direct and catalytic polycarbonate formation reaction from CO2 and diols. CeO2 acted as an activator for CO2 and diols, and 2-cyanopyridine shifted the equilibrium in favor of the product side by hydration of 2-cyanopyridine, promoting the reaction. Green polycarbonates can be synthesized by combination of the catalyst system with a technique of diol syntheses from biomass.

This catalyst system is effective for direct transformation of CO2, contributing to the effective utilization and emission reduction of CO2. Combination of the catalyst system with a concentration technique of CO2 will bring about much advantage.

• We developed both pH and Cl- imaging plates, which can visualize the pH and Cl- concentration on metal surfaces in acidic environments. The pH range is from 3.0 to 0.5, and Cl- concentration up to 4 M can be measured. Fluorescent dyes are successively used for pH and Cl- imaging in the field of biology, but their sensitivity tends to be insufficient in acidic and/or highly concentrated chloride solutions. A glass plate with a sol-gel sensing layer, which contains a pH indicator or a Cl- sensitive florescent dye was fabricated and validated using the solutions with various pH values and Cl- concentrations. Changes in the pH and Cl- distribution on stainless surface in an acidic environment were measured quantitatively.

The newly developed imaging plates can be used to investigate the mechanism of various chemical reactions, such as corrosion, which occurs in an acidic environment. Micro-flow imaging using our sensing technique will be a promising approach to understand the catalytic chemistry of metal surfaces.
強調

• Plasma sterilization has been developed as an alternative sterilization method due to its chemical activity, operation at low temperature and atmospheric pressure, low power consumption, low cost and safety. We have studied a mechanism of chemical species generation and transport in a plasma flow and, the sterilization efficacy and mechanism for several plasma sources at atmospheric pressure, such as a microwave plasma flow, a dielectric barrier discharge in a tube and a water vapor plasma flow. We already clarified that the damages of outer membrane and destructions of the cytoplasmic membrane of Escherichia coli by exposure to the microwave plasma flow. Fig. 1 shows the effect of plasma exposure on the E. coli. When the E. coli was exposed to the plasma, the height of the E. coli decreased and the potassium leakage of cytoplasmic material increased. For sterilization in a tube, we also clarified that an induced flow in the narrow tube by DBD transports chemical species and sterilize the whole inside surface of a tube as shown in Fig. 2. We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

• Fukuyama laboratory studies novel material processing based on chemical thermodynamics with high-temperature thermophysical property measurements. As examples, we are developing new crystal growth processes to bring a breakthrough in nitride-semiconductor devices, which are promising materials for next-generation optical devices applied in environmental, medical, bio and information technologies fields. Database of thermophysical properties of materials is needed for modeling heat and mass transports in materials processes.

A new thermophysical property measurement system is currently under development, which enables accurate measurements of heat capacity, thermal conductivity, emissivity, density and surface tension of high-temperature melts, utilizing electromagnetic levitation in a dc magnetic field.