All Data

To clarify the effects of intertidal groundwater discharge on macrofaunal community structures of tidal flats, the species richness, abundance and biomass of macrobenthos at the groundwater-seepage area were assessed quantitatively, measuring environmental conditions including sediment temperature, median diameter, ORP and ignition loss, and salinity, water temperature and nutrient concentration of pore water at four sites (Nakatsu River mouth, Sanbyakuken, Higashihama, Oshinden) on the Nakatsu tidal flat, Oita prefecture, Japan, at low tides in June and July, 2019. A total of 1,233 individuals, belonging to 51 macrobenthic species (37 families) were collected. Mean species richness and biomass were significantly greatest at Higashihama, whereas mean abundance was greatest at the Nakatsu River mouth. Lower species richness, abundance and biomass were recorded at Sanbyakuken. At Higashihama, infaunal species such as the bivalve Glauconome angulata and polychaete Ceratonereis erythraeensis were dominant in the lower salinity and higher nutrient environments. A canonical correspondence analysis showed a positive correlation between nutrients and dominant bivalve abundance. The overall results suggested that intertidal groundwater influences the macrofaunal community structure, providing low salinity and nutrient-rich conditions, which contribute to the high productivity and diversity of marine organisms on tidal flats.

The vertical migration of the first stage of five diadromous atyids (Caridina multidentata, C. typus, C. leucosticta, C. serratirostris, Paratya compressa) and two diadromous palaemonids (Macrobrachium japonicum, M. formosense) and a non-diadromous palaemonid shrimp (M. nipponense) and second zoeae of C. multidentata and M. formosense were observed under different light and salinity conditions. The first and second zoeae spread over the whole of the water column during darkness, and sank to the bottom under the light independent of the various salinity and light conditions, though there were slight differences among species. The swimming ability of the zoea is limited, thus this vertical migration is considered to be not useful for homing migration. This vertical migration at night is considered to be useful in order to feed on organic material and avoiding predators on the bottom.

The Japanese lates, Lates japonicus is an endemic fish to the Pacific coast of southern Japan, and commonly found in estuaries and coastal waters of Miyazaki and Kochi Prefectures. The larvae, juveniles and young fish stay in the eelgrass, Zostera japonica beds in brackish water areas. Effects of water temperature and salinity on feeding and growth of immature L. japonicus were studied using combinations of seven levels of temperatures (16 to 28℃) and 6 different salinities (9 to 34 ppt) over two experimental periods each of 30 days. At each of these conditions, ten fish were reared in aquaria for periods of 30 days. Based on values of the daily feeding rates, specific growth rates and feeding efficiencies, we found that immature L. japonicus were euryhaline and at salinities ranged from 9 to 34 ppt showed similar feeding and growth rates. The suitable water temperature range was 22 to 28℃, and the optimal water temperature range was 26 to 28℃ for feeding and growth for immature L. japonicus.

This paper shows the vibration characteristics of a sliding bearings. Especially, the self-excited vibration to be called as oil whirl generated in sliding bearing is studied in the current paper. Three methods like trajectory analysis, tracking analysis and frequency analysis of shaft vibration are analyzed to clarify the vibration characteristics of oil whirl. The oil whirl in a sliding bearing is a characteristic self-oscillation, which occurs at a rotation speed less than the twice of the critical speed of the experimental system. In addition, when oil whirl and shaft unbalance are simultaneously generated in a sliding bearing, the frequency response in all domains of frequency is suddenly become larger compared to that in the case of the only oil whirl. It seems that simultaneous development of oil whirl and shaft unbalance generate the large damage to the rotary machinery system. Furthermore, the amount of whirling to the shaft generated by the oil whirl are identified large in the horizontal, vertical and axial directions of sliding bearing. Particularly, the amount of whirling in the horizontal direction is identified larger, because, there is no suppression as gravity and structural barrier in this direction like that in the vertical and in the axial directions.

In order to research useful organic nitrogen, survival and growth of Neopyropia yezoensis protoplasts were examined using L-arginine (Arg), L-glutamic acid (Glu), Inosine (Ino) and taurine in 0.1, 1.0 and 10 mM. For survival rates for 1 week in culture, there were no significant differences except Glu in 1.0 and 10 mM. For growth for 3 weeks in culture, Arg in 10 mM was grown over two-times higher compared with control. On the other hand, growth in Glu and taurine were suppressed under every condition. Moreover, growth in Ino in 10 mM was suppressed. Our data suggested that Neopyropia yezoensis use directly organic nitrogen and has a potential to induce growth using organic nitrogen.

In order to identify effective amino acid species, survival and growth of Neopyropia yezoensis protoplasts cultured using 18 amino acids were examined. Survival rates of each protoplast cultured for 1 week with arginine, asparagine, ornithine and tyrosine were similar to that of the control condition. Other amino acids significantly reduced the survival rates than the control. Growth of each protoplast cultured for 2 weeks with β-alanine, arginine, glutamine, histidine, lysine, ornithine and phenylalanine were significantly higher than that of the control. Histidine might be useful to make only thallus grow, although survival rate was very low. Arginine and ornithine had potentials to be able to promote the growth without negative influences on the survivals of nori cells.

We investigated the oxygen and acid–base status of the noble scallop Mimachlamys nobilis during air exposure for 24 h. The hemolymph of noble scallop was collected from the adductor muscle, and O_2 partial pressure (Po_2), pH, CO_2 partial pressure (Pco_2), and bicarbonate ion concentration ([HCO_3^–]) were examined during air exposure. Hemolymph Po_2 decreased from 69.5 torr (mean value) to 46.3 torr during air exposure for 6 h, and reached to 19.0 torr after 24 h. The hemolymph Po_2 of air-exposed noble scallops decreased gradually and caused progressive hypoxemia by hypoventilation of the ctenidium. Air-exposed noble scallops showed a reduction in pH and elevation of Pco_2 and [HCO_3^–] of the hemolymph. In air-exposed noble scallops, the hemolymph pH decreased from 7.460 to 7.045 at 6 h and to 6.348 at 24 h. The hemolymph Pco_2 increased from 1.30 torr to 5.05 torr at 6 h and to 56.6 torr at 24 h during air exposure. The [HCO_3^–] increased from 1.26 mM/L to 1.88 mM/L at 6 h and to 4.19 mM/L at 24 h. N32From these results, in the first 6 h of air exposure, noble scallops mainly underwent respiratory acidosis by excess accumulation of CO_2 due to hypoventilation. Meanwhile, after 24 h of air exposure, noble scallops showed mainly metabolic acidosis partially compensated by mobilized [HCO_3^–] from the shell.

In the fishery industry, fishing nets tend to be in the water for a long time. Therefore, there is a possibility that the fishing nets will be broken by marine animals or “Kyucho”； it stands for the violent currents caused by tides or typhoons. It is necessary to repair fishing nets as soon as possible for preventing fishes from escaping to outside of the fishing net. However, a great deal of labor is required to lift and repair fishing nets. In addition, high water pressure and low water temperature may make it difficult for divers to work underwater. Therefore, underwater robot is useful to work instead of divers under such severe situations. The author suggests development of the underwater ROV (Remotely Operated Vehicle) type robot that can move on fishing net with magnet tires and repair the net using manipulators. This paper introduces the development and performance evaluation of the underwater robot using magnetic mobile mechanism.

In this research, aiming at efficient cooling of the locally concentrated heating part of the electronic element, a new concentric circular microchannel plate that can efficiently cool the CPU is designed in consideration of the heat generation characteristics of the CPU. Then, we conducted an experiment on heat transfer when water was used as the refrigerant for this new microchannel plate, and grasped the basic heat transfer characteristics. Furthermore, by comparing the results with the straight microchannel plate having a simple structure, the heat transfer promotion of the concentric microchannel plate was examined. By using a concentric microchannel plate, the temperature at the center of the heater can be maintained at about 25℃, and even when compared with a straight microchannel plate, the temperature rise can be suppressed by about 8 to 23℃. The heat transfer coefficient of the concentric circular microchannel plate is 6 to 8 kW/m^2 K, which is almost constant, and about four times higher than the heat transfer coefficient of the straight microchannel plate at the same heat quantity and the same flow rate. In addition, the research results were compared with the previously proposed experimental correlation equation for single phase forced convection laminar heat transfer of straight microchannnels.

Learners of thermodynamics learn a basic thermodynamic state quantity “entropy” which is challenging to understand owing to multiple reasons. First, entropy is explained using multiple defining equations； intuitively understanding the meaning from the equations can be difficult. Second, entropy is often explained in terms of “clutter” and “disorder” of energy； however, the correspondence between these concepts and the defining equation is not obtained intuitively. Therefore, in this study, we considered a virtual lattice space in which gas molecules are arranged and developed a model that enables intuitive understanding and quantitative calculations using defining equations. Specifically, the model was implemented in spreadsheet software with 100 gas molecules in a virtual space of 100 lattices. The model showed that even such a simple model can define thermodynamic quantities and quantify the number of cases Win Boltzmann’s equation from the viewpoint of the arrangement of molecules in lattice space. This is a tool that can calculate and quantitatively examine all entropy from multiple entropy-defining equations. This calculation sheet shows that the calculated values of entropy by the Sackur–Tetrode equation and Boltzmann’s equation are almost the same. Furthermore, the entropy difference calculated using the thermodynamic defining equation dS = dQ/T was also consistent with the values by other equations. Therefore, the model can specifically calculate the values of various entropy-defining equations.

Recently overbrowsing by fish in cultivation of the wakame Undaria pinnatifida has become problematic and the black scraper Thamnaconus modestus is suspected of the feeding damage for the cultured U. pinnatifida as well as a few herbivorous fishes and the Japanese black seabream Acanthopagrus schlegelii, but aspects on feeding behavior and bite scars of the species are extremely limited. We examined characteristics of bite scars left on thalli of the cultured U. pinnatifida by feedng of T. modestus in a tank experiment. The species showed active feeding behavor of the cultured U. pinnatifida and conspicuously consumed juveniles rather than adults. Bite marks left on blades were categorized into three shapes of arc, ellipse and serration and particularly the ellipse-shaped bite mark is characteristic of T. modestus, unknouwn for other overbrowsing fishes. Additionally cut surfaces of those bite marks were edged with irregular gentle concaves. The shape of bite marks on the thalli was thought to be useful for identifying the fish species that caused the feeding damage of the cultured U. pinnatifida.

Two types of stratified [two-layer； inner layer (L0) and outer layer (L1)] granules were observed in the neutrophils (neutrophil granule, NG： type 1, NG1a； type 2, NG2) of larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri collected in a tributary of the Koyagawa River in Yamaguchi Prefecture. The NG1a consisted of chromophobic L0 and chromatophilic L1. On the other hand, the NG2 had chromatophilic L0 and chromophobic L1. The L1 of NG1a and L0 of NG2 showed a variety of colors [eosinophilic or basophilic (orthomethylenophilic or metaazurophilic)] depending on the staining conditions. These layers were positive for alkaline phosphatase, α-naphtyl acetate esterase and Sudan black B. Some enzymes, such as acid phosphatase, ꞵ-glucuronidase, and naphthol AS-D chloroacetate esterase were detected in the L0 of NG2. The neutrophils lacked α-naphtyl butyrate esterase and peroxidase.

Two types of stratified granules (two-layer) were observed in the eosinophils (eosinophil granule. EG： type 1, EG1； type 2, EG2) of larva (ammocoetes) of far eastern brook lamprey Lethenteron reissneri collected in a tributary of the Koyagawa River in Yamaguchi Prefecture. The EG1 consisted of inner eosinophilic layer (L0) and chromophobic outer layer (L1). Dark (low light transmittance) inclusion structure (IS), which was various size and morphology (round, oval, rod, or spindle), was observed in the L0 of many EG1 (only one IS in a EG1). The IS was found in the cytochemical staining preparation, but not in the preparation stained with May-Grunwald (MG), Giemsa and MG•Giemsa. Therefore, recognition of IS was affected with the eosin-stained L0 of EG1. The EG1 classified into three subtypes (EG1a, EG1b and EG1c) based on the optical artificial image (OAI) of IS in L0. The EG1a had no OAI (probably no IS). The OAI of both EG1b and EG1c were larger than IS. The former was round or oval chromophobic area (OAI-1), and latter was expanded and rugged (threedimensional) image (OAI-2； chromophobic； round, oval, or rod). The EG1a may be prototype of EG1. The EG1 showed no positive reaction by various cytochemical stains. The EG2 had chromophobic inner layer (L0) and basophilic (orthomethylenophilic) outer layer (L1). Some enzymes (alkaline phosphatase, acid phosphatase, ꞵ-glucuronidase, α-naphtyl acetate esterase, naphthol AS-D chloroacetate esterase) were detected in L0 of EG2. The eosinophils lacked α-naphtyl butyrate esterase and peroxidase.

Mentaiko, a seasoned cod roe, is one of the main food products in produced from the ovary of Walleye Pollock in Japan. Walleye Pollock roe is predominantly used in the preparation of Mentaiko, with limited other applications. This study showed the processing procedure for an edible film from the Walleye Pollock roe. A few conditions were identified wherein the film could be prepared during processing of the roe. In the first step, water-soluble proteins were extracted from roe samples employing a pH 12.0 phosphate buffer. The pH of this mixture was subsequently adjusted to pH 6.0, mixed with 1.0% transglutaminase and heated at 70℃ for 20 min. Finally, the product was dried in silicon cases suitable for the preparation of edible films. Evaluation of the dried film indicated some improvement in terms of flexibility compared to similarly produced films. During the evaluation of various film-forming solutions, an increase in the amount of surface hydrophobic groups and/or surface sulfhydryl groups was associated with an increased film production. We showed that the edible film can be produced from the proteins of Walleye Pollock roe.

This study examines the roll of Ube municipality to build collaboration with sales businesses in local fishery sector. Ube city adopted “Evidence－Based Policy Making” to make the next fisheries promotion plan. They conducted questionnaire survey to the local fishery sector and customers and made the first draft of the promotion plan according to the result. Members of the committee were also the local fishermen, distributers and representative from the tourist industry and they discussed and understood the present situation and problem of the community and became awareness of the necessity of their new action. Thus they could take the first step to build a cooperative business relationship among local fishery sector.

In the United States, the Korean War (1950–1953) has long been known as the “forgotten war.” However, the war was a watershed for racial minorities in the U.S. military. The U.S. racial policy was changed drastically after U.S. president Harry S. Truman signed Executive Order 9981 in 1948. This study analyzes the military service of Japanese American Nisei (the second generation) who served in the Korean War. The goal of this study is to clarify the transitions of social status of Nisei before and after their service. The paper highlights the Nisei’s motivation to serve in the military, using semi-structured interviews of Californian veterans that I conducted from 2008 to 2019. Most were Nisei and had U.S. citizenship as their birthright. However, their citizen status was insecure even in the fifties, and racial discrimination prevented them from obtaining adequate employment or college education. The Korean War GI Bill benefits definitely supported them after they returned from the battlefield. In this sense, military service in the Korean War became a pathway to success in the post-internment era for Nisei, yet it also revealed their unstable social status. This paper categorizes their motivations to serve from three elements ： socioeconomic reasons, honor and dignity as U.S. soldiers, and their loyalty and patriotism for the United States. The multiple voices of my interviewees shows that while their difficult situations were certainly critical elements among their motivations for service, their various experiences still should not be considered as simply monolithic.

We investigated the oxygen and acid–base status of the densely lamellated oyster, Ostrea denselamellosa, during air exposure for 24 h. The hemolymph O_2 partial pressure decreased from 68.0 torr (mean value) to 52.1 torr during air exposure for 18 h, and reached 42.1 torr after 24 h. The hemolymph pH decreased from 7.579 to 6.798 at 18 h and to 6.361 at 24 h. The hemolymph CO_2 partial pressure increased from 1.30 torr to 40.9 torr at 24 h during air exposure. The hemolymph bicarbonate concentration increased from 1.36 mM/L to 2.81 mM/L at 24 h. The hemolymph calcium ion concentration increased from 8.2 mM/L to 10.9 mM/L at 24 h. From these results, it was revealed that the densely lamellated oysters caused a progressive hypoxemia by hypoventilation of the gill during air exposure. The densely lamellated oysters were inhibited from releasing CO_2 from the gill by hypoventilation, and respiratory acidosis was caused due to the accumulated CO_2. The densely lamellated oysters exposed to air for a long time developed metabolic acidosis due to anaerobic metabolism partially compensated with mobilized [HCO_3^–] from the shell valve.

To improve breeding techniques for aquarium freshwater pufferfishes, hormone injection (hCG, 10 IU per g)-induced maturity and insemination of Auriglobus modestus from Thailand were undertaken, and morphological development of eggs and early stage larvae observed. Artificial insemination was performed two to five days after hormone injection. Although no fertilized eggs resulted from artificial insemination utilizing a wet (freshwater) method, an isotonic (sodium lactate ringer solution) method produced 458 fertilized eggs out of 787 eggs (fertilization rate 61.7%) spawned by one female, although only 8 larvae (1.7%) eventually hatched. Eggs were oval [long axis 2.05 ± 0.06 mm, short axis 1.68 ± 0.06 mm (n = 5)], translucent, demersal, and adhesive, and contained a number of small yellow oil globules. Oval eggs are unusual among pufferfishes, although common in the genus Chonerinos, an indication of the genetic closeness of the latter and Auriglobus, but also suggesting ecological similarity. The eggs hatched after 2 days, larvae one day after hatching [4.54 ± 0.34 mm NL (n = 9)] having a large yolk sac. However, the mouth remained unopened, the optic vesicle uncolored, and the pectoral fin membrane undeveloped, except for small knob-like rudiments. Seven days after hatching, larvae [5.22 ± 0.10 mm NL (n = 3)] had lost the yolk sac and acquired rudimentary soft rays in the pectoral, dorsal and anal fins. All larvae died after eight days. DNA barcoding comparisons (COI gene, 652 bp) of several pufferfish genera indicated a close genetic relationship of Auriglobus and Chonerhinos, being nested in the same clade.