Homma KYOJI (本間 恭二)

A prospect system is offered to detect the plant vermin (e.g. larva of lamellicom beetle) living in the soil without digging up the soil by using a C-band microwave sensor (mean frequency: 5GHz). The characteristic of the prospect system is required to detect explicitly the behavior of vermin moving underground in the vicinity of the surface. The prospective characteristic, however, is limited by the magnitude of microwave attenuation (attenuation constant α) traveling in the soil which is depended on water contents of the soil. First of all, relation of microwave attenuation and water contents of the soil is measured for "Akadama" soil and "Kanuma" soil with uniform grain size, which are fundamentally used in gardening. Detectable critical transmission depth of soil for each water contents is confirmed as the result of the experiment. α was detected quantitatively varying the magnitude of vibration amplitude of mini-speaker (frequency: 1Hz, displacement: 0.1mm, 0.2mm, diameter of diaphragm: 25mm) embedded in the water content controlled soil (volume water contents: 0.3g/cm^3). In this case, detectable critical transmission depths of soil were 105mm, 125mm for the displacement amplitude 0.1mm, 0.2mm. The real movement of the larva of lamellicom beetle (head around width: 4mm, body length: 25mm) embedded in the soil was measured using the system. Critical transmission depths of the soil were 200mm and 100mm for the case of α: 0.1Np/cm and α: 0.2Np/cm. It was confirmed that the system is able to detect the vermin, if the moisture content of the soil is small.

Mussel adhesive protein (MAP) shows promise for the future as a new artificial adhesive material for bonding surgical incisions. The adhesive properties of MAP, however, have not been clarified until now. The purpose of this study was to assess the adhesive strength of MAP with respect to various substrates. The effect of curing temperature on the curing time of MAP after bonding to the substrate was also investigated. Adhesive strength was measured, using a newly developed peel test, using byssus preparations exposed to different curing temperatures (20°C, 40°C, 70°C) for 24 hours following an initial 48 hours of curing at 20°C. Adhesive strength depended on the curing temperature, being 19% lower at a curing temperature at 40°C than at 20°C, and 41% lower at 70°C. In terms of its adhesive strength, MAP may thus be suitable as a medical adhesive in surgery.

Environmental changes due to global warming greatly influence ecological systems including those of plants. Diagnostic technologies using non-destructive inspection methods to evaluate environmental stress are few. Acoustic emission (AE) is applied to plants under water stress and the damage is measured. Cavitation phenomena are created by negative pressure in plants because of the lack of water in vessels or tracheids. Since shock waves due to cavitations create AE, the water stress state of plants can be monitored in real time by measuring AE. In this paper, AE events due to cavitation were measured in the drought-treated Ginkgo biloba L., Ficus spp., and Lycopersicon. In all plants examined, AE events increased during drought. In a short-term drought experiment, AE events were stopped by supplying water, but not in a long-term drought experiment. In Ginkgo biloba L. and Ficus spp, a temporary decrease of AE events was observed during drought. Plants adjust their internal water balance through certain self-defense mechanisms.

Present study reports acoustic emission (AE) technique to evaluate corrosion damages of bottom plates (floor conditions) in above-ground tanks. Artificial AE signals were generated by pencil lead breaks at arbitrary locations on the bottom of a tank (300 kL in capacity) to investigate accuracy of AE source location. Attenuation of AE waves was shown to be very small in liquid. AE source location analysis was conducted, using a neural network (NN). Input and output units of the NN were arrival time differences between four AE sensors and coordinate of the AE source location, respectively. Arrival time differences of AE waves were determined by visual observation of the first signal arrivals and threshold crossing times of the AE signal normalized by its peak amplitude. It was concluded that accurate AE source location can be obtained by the decision process resulted from automated readings of threshold crossing time, based on the NN trained method by theoretical calculation.

Mussels living in the ocean adhere to shore reef and each other with byssus formed by insolubilization of a bonding protein, whose application to the new bio-adhesion material has been expected. Their adhesive strength has not been accurately measured because peeling test method is not established since the contact areas between a plaque and the substrate are less than 1 mm². Present paper attempts to measure adhesive strength of the plaque using original simple peeling test method and investigates the influence of environmental change on the adhesive strength and the change of the adhesive strength in the lapse of time. The results show that the-adhesive strength of the plaque decreases with the change in the environment by moving mussels from the beach to an experimental environment and the adhesive strength changes along with the elapsed time after the plaque is formed.