Thermal death of Escherichia coli suspended in solutions contained sodium ion at several pH values (pH 5.4-7.4) was investigated. The thermal death of Escherichia coli suspended in phosphate-buffered saline (PBS; pH 7.4) was accelerated in comparison with that of Escherichia coli suspended in distilled water. The presence of sodium and potassium ions in PBS was found to accelerate the thermal death of Escherichia coli; the thermal death of Escherichia coli suspended in sodium chloride solution or sodium monohydrogen phosphate solution was accelerated at a neutral pH of the bacterial suspension in comparison with a mild acidic pH. These results indicate that the thermal death of Escherichia coli at neutral pH was accelerated by the addition of sodium ions.

Non-destructive estimation of aquatic products’ volume is important for efficient feed utilisation, and for determining the appropriate time for landing. To enable this, we propose a double cavity underwater Helmholtz resonator for precise aquatic products’ volume estimation. The fundamental principles were developed and the resonator consisting of the generating cavity and the sample cavity was fabricated. By attaching an underwater speaker to the generating cavity, sweep sound was generated and captured using the speaker’s impedance technique. Air, which is less dense than water, was inserted into the sample cavity to mimic aquatic samples of increasing volume. Resonance frequency decreased as air volume increased. A high linear correlation with an R² of 0.99 between the actual and predicted volume was obtained.

The grain loss, a standard for determining the operating performance of for multi-crops, is 2 % for paddy, 1 % for wheat, and as high as 4 % for buckwheat. In this study, to reduce the grain loss and improve the cleaning performance, the aerodynamic characteristics of buckwheat were investigated, and the coefficient of drag and lift necessary for predicting the scattering range of buckwheat were modeled. Owing to attitude changes, the buckwheat was found to have greater coefficient variations than paddy, wheat, and soybean. Thus, the overlap of scattering range between the buckwheat and trash increased, suggesting that the amount of buckwheat discharged outside the machine increases when trying to improve the quality at the clean grain outlet.

We have applied PPP (Precise Point Positioning) using the LEX (L-band Experiment) signal of the QZSS (Quasi-Zenith Satellite System) to a robot tractor for precise farming. The QZSS transmits augmentation signals coded in the LEX signal to realize centimeter-class positioning accuracy. The usage of PPP in autonomous navigation is restricted in ambiguity resolution. Experiments using a commercial QZSS receiver reveal that the PPP converges to different results at the same position, and the results drift after convergence. We proposed a bias identification method based on landmarks to overcome these limitations. The proposed method was effective for navigating a robot tractor with 5 cm accuracy at a speed of 3.6 km/h.

This study aimed to determine the local adaptability of rice cultivation using a transplanting method that employs high-density seedling mats in Japan via empirical cultivation. The study involved evaluation by 342 farmers across 36 prefectures. Considering the total mean of the demonstration sites, seedling height was 13.3 cm, 7.6 trays were used for planting, and the yield was 515 kg. At 57 % of the demonstration sites, the yield was equal to or better than that obtained using the conventional cultivation methods. Therefore, the seedling quality and yield were secured. The high-density seedling mat method was found to be highly adaptable to different regions. Moreover, the farmers reported a reduction in both labor and seedling production costs.