In recent years, space agencies including NASA, academia, non-profit organizations, and private companies have been considering potential human settlement sites on Mars. The First Landing Site/Exploration Zone Workshop for Human Missions to the Surface of Mars was conducted in the United States in 2015. At the workshop, 47 teams analyzed separate exploration zones under the same rubric and criteria to identify potential landing sites, areas of scientific interest, and areas of resource interest. Most of the studies focused primarily on scientific exploration, and did not analyze from a perspective of settlement. In this paper, Mars Society Japan compared the same 47 exploration sites from four main perspectives: "local water resource usage," "atmospheric thickness corresponding to altitude," and "latitudes with sufficient sunlight for agriculture," to determine settlements capable of accommodating up to 10,000 people. In total, four locations were selected as candidates. Two of the locations coincided with potential settlement sites selected by SpaceX for city construction.

The influences of quercetin on the productions of lipid peroxides, anisidine-reactive compounds and ozone in autoxidation of α-linolenic acid were investigated. Lipid peroxide concentration, anisidine value and ozone concentration significantly increased in the autoxidation of α-linolenic acid for 5 days. On the other hand, the addition of quercetin as a natural antioxidant agent efficiently suppressed the increases in the generations of these peroxidation products. The increase in ozone concentration was correlated with the increase in anisidine value, but not the lipid peroxide concentration. The oxidative cleavage of double bonds in α-linolenic acid and lipid peroxides by ozone generated in the autoxidation seems to be involved in the productions of anisidine-reactive compounds. Quercetin inhibited the process of productions of anisidine-reactive compounds by inhibiting the generation of ozone from lipid peroxides. Next, the direct effect of autoxidized α-linolenic acid on λDNA was evaluated. The autoxidized α-Linolenic acid degraded λDNA dependently upon the increase in anisidine-reactive compounds. On the other hand, the addition of quercetin during the autoxidation of α-linolenic acid significantly inhibited the degradation of λDNA. 2,4-Heptadienal and trans-2-pentenal efficiently degraded λDNA, suggesting that the DNA-degrading compounds in autoxidized α-linolenic acid might be these aldehydes.

Recovery of plant nutrients from food residue is one of the most effective methods for resource recycling. To use food residue for hydroponics, the organic matters have to be mineralized and the nutrients have to be dissolved. Anaerobic digestion, biological oxidation, anaerobic digestion followed by biological oxidation, and wet oxidation are treatments to break down organic matter. The decomposition products of these processes are in liquid form and would be used as liquid fertilizer. The authors investigated the difference in the behaviour of nitrogen, potassium, and phosphorus in each treatment. Nitrogen was converted to ammonium by anaerobic digestion and wet oxidation, and to nitrate by biological oxidation. Potassium did not change significantly with treatment. The percentage of dissolved phosphorus in all treatments, especially in the microbial treatment, was smaller than in food residue. This is probably due to phosphorus binding to other ions and uptake by microorganisms during the treatment process.

Green onions (Allium fistulosum L.) are an essential flavoring vegetable in Asian cuisine with high nutritional value. To ensure their stable future production, efficiently cultivating them in plant factories is necessary. In this study, we investigated the effects of spectral photon flux density and lighting position and direction for green onion production using two cultivars (ʻWhite Starʼ and ʻFukuichi-Negiʼ). First, we investigated the effects of four types of light-emitting diode (LED) lamps with or without far-red light and different red/blue (R/B) ratios on the growth of the green onion cultivars. ʻWhite Starʼ had the highest shoot fresh weight when grown under low blue-light ratio LED lamps with far-red light, while ʻFukuichi-Negiʼ had the highest shoot fresh weight under medium blue-light ratio LED lamps. The R/B ratio and far-red light affected green onion growth, with the effect varying among the varieties. Furthermore, we investigated a light irradiation method to increase the production efficiency of green onions. We compared the growth of the two green onion varieties by irradiating the top of the plants (conventional method) or their sheath base from the lateral direction (sideward irradiation). The results showed that the shoot fresh weight of ʻWhite Starʼ and ʻFukuichi-Negiʼ grown under sideward irradiation were 1.5- and 1.3-fold higher than those under the conventional method, respectively.

This study provides important knowledge for improving the efficiency of green onion production in plant factories using LEDs.

To investigate effects of CO₂ concentration, light intensity, and nutrient solution strength on the growth of wasabi (Eutrema japonicum (Miq.) Koidz.) seedlings, they were grown in environmentally controlled chambers. In the first experiment, single effect of CO₂ concentration on growth of wasabi cultivar ʻIzumaʼ was investigated. The dry weight of the whole seedling was increased more under enriched CO₂ concentrations (1000 and 2000 ppm (v/v)) than under ambient CO₂ concentration (400 ppm). However, the CO₂ effect to raise photosynthesis was weakened in the latter half of the experiment. To sustain the effect of the enriched CO₂ throughout the whole seedling cultivation period and maximize the wasabi seedling growth, the wasabi seedlings were grown under different light intensities and different nutrient solution strengths in the second experiment. Two wasabi cultivars ʻIzumaʼ and ʻFujimidoriʼ were used. ʻFujimidoriʼ is a newly developed cultivar that is more tolerant to high temperatures. The results revealed that ʻFujimidoriʼ had the highest whole dry weight under enriched CO₂ concentration (1000 ppm), higher light intensity (200 µmol m^-2 s^-1), and higher concentration of the nutrient solution. Contrary, the whole dry weight of ʻIzumaʼ under such environmental conditions was almost the same as that of ʻIzumaʼ grown under a lower concentration of nutrient solution but enriched CO₂ concentration and higher light intensity, and under lower light intensity but enriched CO₂ concentration and higher concentration of nutrient solution. This suggests that a combination of a higher concentration of the nutrient solution and higher light intensity cannot amplify the CO₂ effect on ʻIzumaʼ growth. The difference in the environmental response between the two cultivars seemed to be partially caused by the different temperature tolerances.

To evaluate the effectivity of ʻCoral gravel agricultureʼ on cherry tomato, we examined the effects of silicon and calcium included in solid medium on growth, yield and photosynthesis. Total fruit yield and total number of fruits were increased by silicon material in solid medium. Simultaneously, net photosynthetic rate at later growth stage was increased by silicon material. However, the yield and photosynthesis parameters were no affected by foliar spray of silicon. These effects indicate that the silicon thorough root was the important on yield and dry matter production of cherry tomato. Moreover, the calcium material in solid medium increased the total fruit yield in cherry tomato. The photosynthetic rate was slightly increased by calcium material, but the effects was not significant. Therefore, the calcium through root was the important factor in cherry tomato, but the importance of calcium was smaller than silicon. These results indicated that silicon and calcium in Coral gravel promoted the growth and photosynthesis, and consequently increased the yield of cherry tomato.

We investigated the grain thickness distribution of flavorful rice (Oryza sativa L. cv. Koshihikari) in Japan. A total of 150 samples were collected from three Special A rice cultivation areas (with high ratings for taste quality) and compared with 30 samples collected from other rice growing areas. We found that the flavorful rice samples tended to have greater grain thickness than the control samples. There were multiple differences in the physicochemical properties of rice samples with different thicknesses. In general, the thicker rice grains had higher amylose contents and lower protein contents. Higher amylose and lower protein contents were correlated with higher taste values and cooking qualities. The results suggested that we can improve the taste quality of rice by selecting grains with greater thickness. We can also sort rice with different protein and amylose contents by fractionation based on thickness. This fractionation method could help address the increasing demand for high quality rice.

The freshness of leafy vegetables is one of the most essential requirements that plant factories need to meet in order to attract consumers. The farmbox^® developed by Farmship, Inc. is an in-store plant cultivation system. It can be placed on the floor of a supermarket where it can be used to grow aromatic herbs with lighting and irrigation equipment. This system allows consumers to purchase extremely fresh vegetables by harvesting the aromatic herbs by themselves and minimizes the time lag between the time of harvest and purchase, which is a major factor affecting freshness. In addition, the flavor/smell, which is attributed to volatile organic compounds (VOCs) that are emitted by plants, is also one of the most important factors affecting freshness, especially for aromatic herbs. In this study, we investigated the effect of in-store cultivation using a farmbox^® on VOC emissions from sweet basil (Ocimum basilicum) leaves. In the standard commercial production process, control plants were grown under a PPFD (Photosynthetic Photon Flux Density) of 300 μmol m^-2s^-1 for 16 hours a day for 23 days (16L:8D). Then, for the light treatment, plants were maintained in the farmbox^® and subjected to lighting with a PPFD of 130 μmol m^-2s^-1 for 4 hours a day for an additional 7 days (4L:20D). For the dark treatment, plants were maintained in the farmbox^® under continuous dark conditions for an additional 7 days. VOCs emitted from whole and shredded leaves were collected using a closed chamber system and analyzed by GC-MS (Gas Chromatograph Mass Spectrometer) with a thermal desorption system. The emission of typical VOCs from sweet basil, such as eugenol, cineole, linalool, (Z)-3-hexenal, and (Z)-3-hexenol, was observed. In the case of the whole leaves, the emission of cineole during the dark treatment was significantly higher than that from the from the control and the light treatments. Conversely, in the case of the shredded leaves, the emission of (Z)-3-hexenal from both the light and the dark treatments was significantly lower than that from the control treatment. Furthermore, the emissions of linalool and (Z)-3-hexenol from shredded leaves of plants maintained under dark conditions were lower than those of the control. The results suggest that lighting conditions during the preservative cultivation period in the farmbox^® affect the VOC emission profile of sweet basil leaves, and that these conditions can be used to modify the flavor/smell profile of this herb.

To investigate effects of environmental factors in nurseries on growth of Wasabi (Eutrema japonicum (Miq.) Koidz.) seedlings, they were grown in four different sites in Shizuoka and one site in Yamanashi during summer season in 2021 and 2022. At the end of experiment, ratio of shippable seedlings among the seedlings used for experiment was highest (= 80%) at Yamanashi site, followed by Fujinomiya highland site. At the site of Fujinomiya lowland, no shippable seedlings were obtained. Environmental factors affecting the shippable ratio at individual sites seemed to be different, i.e. air temperature, vapor pressure deficit, or light intensity. A multiple regression analysis was applied to clarify the significant factors affecting the shippable ratio. Accumulated air temperature over 30°C, diurnal range of air temperature, light intensity, and yearly-different growing setup have been revealed to be affecting factors. Using the relationship, suitable sites for Wasabi seedling cultivation during summer season were estimated among 55 sites where meteorological data were provided by Japan Meteorological Agency. The number of the suitable sites were 1, 3, and 20 in Shizuoka, Yamanashi, and Nagano prefectures, respectively. Assuming that air temperature was 1°C higher than average of those during 2021 and 2022, the number of the suitable sites was decreased, but Yamanakako village was left, to which our experimental site in Yamanashi was adjacent.

The degradation of rice straw ploughed into a paddy field was studied using ¹³C as a tracer. The changes in the δ¹³C value of soil organic carbon of the paddy field where ¹³C-enriched rice straw had been buried in April 2008 were determined. The amounts of organic materials contained in the buried rice straw decreased to about 50% of the initial value during the first month of the experiment, and thereafter, decreased relatively slowly during the experimental period. The ¹³C concentration in rice plants grown in this paddy field increased rapidly and then decreased. The high ¹³C concentration in the rice plants suggested that they took up carbon derived from rice straw buried in the paddy field soil by photosynthesis. The ¹³C concentration of the air in the hollow stems of the rice plants immersed in a solution of ¹³C-labeled sodium bicarbonate was high. These results suggest that rice can take up inorganic carbon from soil through the roots.

Knowing the stand timber volume in a forest is necessary for good forest management. A typical way to work out stand timber volume is to use the area-based approach (ABA) with airborne LiDAR. The ABA requires checking the model applicability and parameters against other forest areas. The present study developed a stand timber volume estimation based on publicly available data on the Internet. The objectives of the present study were 1) to evaluate errors in stand timber volume using the ABA and 2) to examine the factors affecting these errors. The study area was located in the eastern part of Shizuoka Prefecture, with 15 plots in Cryptomeria japonica-dominated forests and 13 plots in Chamaecyparis obtusa-dominated forests. Errors in stand timber volume were evaluated by comparing the airborne LiDAR results with results of conventional methods. Relative root-mean-square error (RMSE) and bias were 20% and –14% for the coniferous forest parameter and 17% and –11% for the mixed forest parameter, respectively, resulting in underestimations. The multiple regression analysis showed that the determination coefficient (R²) was 0.66, the relative error was underestimated as the total basal area increased, and the relative error was underestimated more for C. japonica than for C. obtusa. The errors in the present study were relatively small compared to seven previous studies. Therefore, the present study showed that estimating the stand timber volume by using the ABA was valid in the eastern part of Shizuoka Prefecture.

The functions of extracellular substances (ESs) that contribute to the protection of cells against ultraviolet (UV) radiation were investigated in the terrestrial cyanobacterium, Nostoc sp. HK-01. The original advanced method was used successfully and was found useful for UV- protective bioassay. Cells with and without ESs were exposed to UV radiation, and results showed the survival rate of the cells with ESs was higher than that of the cells without ESs. The ES of Nostoc sp. HK-01 did not show the specific reflection; however, the high absorption in the UV range, especially UV-C range, was investigated. The results indicated the presence of substances with UV-C protection properties in the ES. Additionally, we confirmed other functions related to cell differentiation, namely, akinete germination, differentiation to vegetative cells, and differentiation to hormogonia, in ES. This phenomenon showed in a limited concentration of ES. In the germination test, contribution of elements in ESs had great effect; however, some inhibiting and promoting effects were confirmed as some organic compound. The occurrence of differentiation in hormogonia by ESs was first examined and confirmed during the early stages of akinete germination. Our results demonstrated that Nostoc sp. HK-01 cells may have unique abilities during cell hydration and drying under harsh environmental conditions.

The processing of wastewater containing high concentrations of hexavalent chromium, commonly used as a powerful oxidant in many industrial production processes, is not readily available in developing countries. Previously, to develop a simple treatment method for wastewater containing high concentrations of hexavalent chromium, we have been investigated the processing of the artificial wastewater using inexpensive inorganic compounds as treatment agents. As a result, it was confirmed that hexavalent chromium ions were specifically removed as the precipitate containing iron chromate complex and iron chromate from the artificial wastewater by adding ferrous chloride after adding calcium hydroxide. In the present study, to evaluate the practicality of this precipitation treatment method, we verified the processing effect of the aged plating wastewater supplied from a metal plating plant complexly contaminated with high concentrations of hexavalent chromium and several heavy metal ions. As a result, hexavalent chromium, zinc, copper and lead ions in the aged plating wastewater were effectively precipitated and removed by this precipitation method regardless of the presence or absence of agglomeration treatment. Furthermore, no significant re-eluting of hexavalent chromium, zinc, copper and lead ions from the fine powders of the precipitates at pH 3-11 was observed on the re-eluting experiments.

The objective of this study was to investigate the changes in soluble sugar accumulation in the main stem, nitrate concentration in Murashige and Skoog (MS) medium, and growth rates of Torenia fournieri ‘Dwarf Blue’ under hypobaric (50 kPa) and atmospheric (100 kPa) conditions with O₂ and CO₂ partial pressures equal to the atmospheric pressure levels. Torenia plants were grown in MS medium at 20% strength without ammonium nitrate by using a reduced pressure plant cultivation system. The plants that were grown at 50 kPa had a greater shoot dry weight and a greater number of floral buds and flowers than those grown at 100 kPa. The soluble sugar concentration in the main apical stem at 50 kPa was higher than that at 100 kPa. The concentration of nitrates in the MS medium at 50 kPa was lower than that at 100 kPa. A reduced pressure of 50 kPa promoted vegetative and reproductive growth in Torenia plants.

The sea urchin Mesocentrotus nudus is a valuable commercial species in Hokkaido and northern Honshu, Japan, where artificial seeds produced in the hatcheries are released on fishery grounds for stock enhancement program. To develop a method for promoting broodstock maturation, we investigated the effects of photoperiod manipulation on the gonadal maturation of this species. Adult sea urchins were reared from December for 9-11 months under manipulated photoperiods where the annual change in day length between the two winter solstices was shortened to 6, 8, and 10 months, or advanced 2 months ahead of the natural photoperiod. Maturation progress was evaluated by observing the wet-squash gonad preparations and spawning reaction tests, which involved observing gamete release from the gonopore after removing the coelomic fluid. Experimental urchins reared under any of the accelerated and advanced photoperiods matured around August, one month earlier than those reared under the ambient photoperiod and the wild urchins collected from the coastal water. We conclude that the maturation of M. nudus can be promoted for early gamete collection in the hatcheries using the artificially accelerated or advanced photoperiods.

Hydroxyapatite (HAp) prepared from baked livestock bone as fine solid powder efficiently inhibited the release of iron ions from the metallic iron plate in a 3% sodium chloride solution. The effects of fine powder HAp on Tafel measurement and anodic polarization using iron electrodes were examined. The response current density in the active region significantly increased depending on the potential on the iron electrode surface without HAp. On the other hand, on the iron electrode surface installed with fine powder HAp, the response current density increased in the active range up to about -0.2 V, and then, the increase in response current density was completely suppressed up to about 0.5V. Next, the surface of the iron electrode contacted with the fine powder HAp after the anodic polarization measurement was analyzed by TEM. As a result, the formation of iron hydroxide layer mainly containing Fe(OH)₃ with a thickness of approximately 1.3 μm between the iron electrode and HAp was confirmed. It was suggested that fine powder HAp strongly suppressed the release of iron ions and electrons with protection of the passivation iron hydroxide layer.

The thermal decomposition mechanism of bivalves and sea urchin spines was investigated to evaluate the potential for using fishery waste material as thermal storage material. The thermal decomposition rate demonstrates an Arrhenius-type temperature relationship. Compared with a CaCO₃ reagent, shells and spines were efficiently thermally decomposed. Despite showing a significant difference in thermal decomposition rate, chemical composition, particle size, and specific surface area, the activation energy of thermal decomposition was only marginally different. The rate-limiting process in thermal decomposition processes could be caused by the CO₂ gas flux, which was emitted from the sample. The CO₂ flux is controlled not only by the geometric surface area, particle seize but also by the crystallographic morphology of the sample. The biologically originated calcite may have efficient heat exchangeability as thermal storage material due to its unique crystal figure and microstructure.

The most popular method for avoiding frost damage to tea leaves in Japanese tea-producing areas is the air stirring method using frost protection fans. To avoid unnecessary fan operation, this study constructed an air temperature sensing system using IoT and examined the stability of data transmission by Sigfox and Wi-Fi modules in an actual tea garden. In a wide range of area, the Wi-Fi router could not directly receive radio waves from the microcomputer connected to the temperature sensors. In addition, Wi-Fi modules experienced frequent data loss, and data acquisition was unstable even with the use of repeaters. On the other hand, Sigfox modules acquired the data from the sensors and sent the data to the cloud without communication failures, regardless of locations and weather conditions. Given the high spatial variation of the tea leaf temperature in the tea garden, this study introduced multi-point measurements by the IoT system. The operating time for the frost protection fans was evaluated using both existing conventional and proposed methods. In most cases, the fan operating time became shorter with the proposed methods than with the conventional methods. At the locations where the minimum air temperatures were lower than the temperature in the reference location, increases in the operating time were considered to avoid the risk of frost. This study confirmed that Sigfox was more suitable than Wi-Fi in the outdoor tea garden and concluded that the effects of multi-point measurements by the IoT system were useful for reducing unnecessary fan operation and avoiding frost risk.