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Journal of National Fisheries University Volume 71 Issue 4 pp. 109 - 122
published_at 2023-03
Neutrophil granules (NG) of adult (mature) far eastern brook lamprey Lethenteron reissneri [L. sp. S (souther form)] were classified into two types of stratified [two-layer; inner layer (L0) and outer layer (L1)] granules (type 1, NG1a; type 2, NG2), like as larva (ammocoetes) of this species. The L0 of NG1a and L0 of NG2 in adult neutrophils were chromophobic, and L1 of NG1a and L0 of NG2 showed chromatophilic. The stainability of those chromatophilic layers with May-Grünwald (MG), Giemsa, or MG-Giemsa were varied [chromophobic, eosinophilic or basophilic (orthomethylenophilic or metaazurophilic)] with a slight difference to larva. As seen in larval neutrophils, these layers were positive for alkaline phosphatase,α-naphtyl acetate esterase and Sudan black B, and some enzymes (acid phosphatase, ꞵ-glucuronidase, and naphthol AS-D chloroacetate esterase) were detected in the L0 of NG2. Alpha-naphtyl acetate esterase was positive in L0 of NG2 of adult neutrophils. Both larval and adult neutrophils lacked peroxidase.
Creators : Kondo Masakazu | Yasumoto Shinya Publishers : National Fisheries University Updated At : 2023-06-15 12:51:37
Journal of National Fisheries University Volume 71 Issue 4 pp. 141 - 151
published_at 2023-03
Growth of immature Lates japonicus in eelgrass (Zostera japonica) beds of the Tomouchi River located at around 4.3 km upstream from the river mouth of the Gokase River, Kyushu Island, Japan was studied by the mark and recapture method and scale reading from September 1998 to March 2004. Newly occurring 0-year-old L. japonicus specimens of 13.9–78.0 mm SL (standard length) in Z. japonica beds of the Tomouchi River in August or September reached sizes ranging 58.8–125.7 mm SL by April and 203.4–232.8 mm SL between October and November of the following year. Monthly changes in specific growth rates of individuals demonstrated that rapid growth months of immature fish were limited to the period of high water temperature (22–28℃) from June to October. Also, it was supposed that the large-sized fish of the 0-year-old fish migrated away from Z. japonica beds after December, however a few fish remained in Z. japonica beds until the following November.
Creators : Takeshita Naohiko | Kondou Takuya | Nagata Shingo | Takahashi Hiroshi Publishers : National Fisheries University Updated At : 2023-06-15 16:44:47
Journal of National Fisheries University Volume 71 Issue 4 pp. 89 - 108
published_at 2023-03
Two types of stratified (two-layered) granules (type 1, NG1a; type 2, NG2) in the neutrophils of inshore hagfish Eptatretus burgei showed eosin-positive (positive site: outer layer (L1) of NG1a and inner layer (L0) of NG2). In contrast, both eosin-positive sites have been reported to be basophilic. From present result, it is clarified that both sites exhibit as follows: L1 of NG1a, eosinophilic and mataazurophilic; L0 of NG2, eosinophilic, orthomethylenophilic and mataazurophilic. The inshore hagfish neutrophils phagocytosed zymosan particles, in vitro. All blood cells showing phagocytosis were identified as neutrophil.
Creators : Kondo Masakazu | Yasumoto Shinya Publishers : National Fisheries University Updated At : 2023-06-14 16:37:03
Journal of National Fisheries University Volume 71 Issue 3 pp. 81 - 87
published_at 2023-03
Embryonic development in giant cuttlefish Sepia latimanus was studied using eggs laid from broodstocks reared in captive condition. 26 embryonic stages were examined in this study and the detail process of organ development was clarified under microscope observation. Blastdisc was visible at the animal pole on the yolk at 2.5 hours after fertilizaton (HAF). The first cleavage occurred at 8.6 HAF. Then embryo developed to the morula stage at 22 HAF. Almost surface of the egg was covered with blastoderm at 10 days after fertilization (DAF). Primordia of main organs such as arms, mouth, mantle, funnel, optic vesicle, gills, statocyst, lens and optic ganglion were formed till 14 DAF. At 15 DAF calcification began in the first striation on the shell. Primordium of the shell became visible at 18 DAF. The number of striations on the shell reached to 5, 9 and 14 at 26, 32 and 40 DAF, respectively. Embryo needed 45 days for hatching. Newly hatched larva was 14 mm in mantle length and had 18 striations on the shell. The process of embryonic development in S. latimanus was very similar as S. lycidas, S. esucurenta and Sepiella japonia. S. latimanus is characterized with large newly hatched larva in Japanese sepiids. It was revealed that the large yolk of S. latimanus induces the growth of the body over a long period in the embryonic stage.
Creators : Oka Masakazu | Tezuka Nobuhiro Publishers : National Fisheries University Updated At : 2023-06-14 15:49:18
Journal of National Fisheries University Volume 71 Issue 3 pp. 73 - 80
published_at 2023-03
Viral edema of carp (VEC) caused by the carp edema virus (CEV) causes economic losses for Japanese koi farms. In this study, we investigated the infectivity and pathogenicity of a domestic CEV isolate (genogroup IIa) in koi carp, common carp and goldfish. The challenge test consisted of 9 groups (n = 15):3 groups each of koi carp, common carp, and goldfish, at 15, 20 and 25℃. These groups were challenged with CEV (3.0×10^3 copies/µL) in duplicate. All koi carp died in the 15 and 20℃ groups, but all survived in the 25℃ group. The surviving koi carp in 25℃ groups showed high PCR positive rates of 66.7 and 73.3%, with VEC histopathological changes observed. For the common carp, 1 and 2 fish died in the 20℃ groups, but no deaths or VEC symptoms were observed in the 15 and 25℃ groups. In all common carp groups, PCR-positive fish were observed along with histopathological changes. For all goldfish groups, no deaths or VEC symptoms were observed. As with the common carp, PCR-positive fish were found in all goldfish groups, yet no VEC histopathological changes were detected. These results demonstrate infectivity of this CEV strain in koi carp, common carp, and goldfish, but low pathogenicity in common carp and goldfish.
Creators : Matsumoto Akane | Honda Kotaro | Takahashi Hiroshi | Kondo Masakazu | Yasumoto Shinya Publishers : National Fisheries University Updated At : 2023-06-14 14:32:17
Journal of National Fisheries University Volume 71 Issue 4 pp. 123 - 134
published_at 2023-03
Based on the findings of past literature, we speculated the existence of two types of stratified [two-layer; inner layer (L0) and outer layer (L1)] granules in the neutrophils (granulocytes; blood cells) of amphioxus (Cephalocordata), especially Branchiostoma japonicum. Type 1 neutrophil granules (NG1a) consist of chromophobic L0 and chromatophilic L1. Other type (type 2; NG2) have chromatophilic L0 and chromophobic L1. The L1 of NG1a and L0 of NG2 show metaazurophilic (purple to blackish purple) in Giemsa staining preparation. Ultrastructurally, these two granule types will not be separately identified. These granules contain intragranular particles (granulons, g) in the L0 of granules. At least, three types of granulons (g-1, g-2, and g-3) are recognized in a granule and localized in L0. Two of them form an agglomerate with short rod shape and two layers (inner layer consisted by g-2, and outer layer by g-3). The agglomerate have been considered as tubular structure or microtubule (misinterpretation). Neutrophils of cyclostome (hagfish and lamprey) also have NG1 [NG1a or NG1b (chromophobic L0 and L1)] and NG2. Further, neutrophil granules of cyclostome also contain granulons (without forming of agglomerate).
Creators : Kondo Masakazu | Yasumoto Shinya Publishers : National Fisheries University Updated At : 2023-06-15 13:23:56
Journal of National Fisheries University Volume 71 Issue 4 pp. 135 - 140
published_at 2023-03
In order to research the actual operation status of fishing vessels by AIS, an effective extraction method is needed even when vessel name, MMSI, and type of ship information are insufficient. In this study, we analysis on the illegal use of AIS for fishing pole to indicate the location of operations and proposes a method for estimating fishing grounds using AIS buoys. Extracted by Vendor ID and vessel name notation and visualized using the kernel density estimation to show the major fishing grounds. The use of AIS buoys is illegal, but if the reception rate of satellite AIS improves, it may be easier to determine the location of operations and prevent damage to fishing gear.
Creators : Matsumoto Hirofumi | Hata Kazuhiro Publishers : National Fisheries University Updated At : 2023-06-15 14:26:41
Journal of National Fisheries University Volume 71 Issue 2 pp. 43 - 55
published_at 2023-01
We aimed to clarify the microhabitat preferences of Atyidae shrimps in the middle to upper reaches of the Hiwasa R. , Kitagawatidani R. , and Mugi R. , Tokushima Prefecture, southern central Japan. Relationships between the shrimp abundance and physical environmental variables were surveyed at six sites in 2011 fall and 2012 spring by setting 5-m line transects delineated with ten consecutive 50-cm quadrats along the riverbank. The dominant shrimp species collected from the riverbanks were Caridina multidentata, Paratya compressa and Neocaridina denticulata. C. multidentata was shown to prefer loose boulder or cobble beds with interstices. When interstices were scarce, the shrimps were found inhabiting among the vegetation. P. compressa was shown to prefer vegetation and boulder or cobble bed in pools. N. denticulata tended to prefer vegetation in darker, gently-flowing areas. Our results insist that the three shrimp species segregate microhabitat under base-flow conditions, but flow reduction may cause microhabitat overlap between C. multidentata and P, compressa.
Creators : Yonezawa Takayasu | Saito Minoru | Hatama Toshihiro | Araki Akira | Oka Naohiro | Hamano Tatsuo Publishers : National Fisheries University Updated At : 2023-06-09 15:31:25
Journal of National Fisheries University Volume 71 Issue 2 pp. 35 - 42
published_at 2023-01
We investigated the hemolymph oxygen and acid–base status of akoya pearl oysters, Pinctada fucata martensii, exposed to air for a short time (4 h) to elucidate the acid–base balance and CO_2 dynamics. The hemolymph O_2 partial pressure (Po_2) in air-exposed akoya pearl oysters decreased from 88.7 torr (mean value) to 29.4 torr at 1 h, and the low Po_2 continued for the next 3 h during air exposure. The hemolymph pH decreased from 7.586 to 7.082 during air exposure for 1 h and reached 6.851 at 4 h. The hemolymph CO_2 partial pressure increased from 0.9 torr to 4.4 torr at 1 h and reached 7.3 torr after 4 h of air exposure. The hemolymph bicarbonate concentration and calcium ion concentration at 0 h (control) were 1.9 mM/L and 9.0 mM/L, respectively, and these properties did not significantly change during air exposure. From these results, it was determined that the akoya pearl oysters had hypoxemia caused by hypoventilation at an early phase of the short-term air exposure. The akoya pearl oysters inhibited the discharge of CO_2 by hypoventilation, and respiratory acidosis was caused due to the excessive accumulation of CO_2. Bicarbonate was not mobilized from the shell valve into the hemolymph during the short-term air exposure.
Creators : Handa Takeshi | Araki Akira Publishers : National Fisheries University Updated At : 2023-06-09 15:09:18
Journal of National Fisheries University Volume 71 Issue 2 pp. 57 - 65
published_at 2023-01
In aquaculture and fixed-net fishing, fishing nets need to be fixed in the water for a long period of time. Therefore, attached organisms such as shellfish, algae, and parasite eggs easily stick to the nets, making periodic cleaning indispensable. A common method is for divers to dive into the water and clean the nets directly with their hands. However, this method is dangerous because it can be fatal to divers due to high water pressure and low water temperature. Therefore, this study considered the possibility of using underwater robot to clean fishery nets in place of divers to avoid these dangers. A mobile mechanism that can move freely along the sides of fixed fishery net in the water has already been developed in this laboratory. In this study, we propose the cleaning system using autonomous robots that automatically cleans aquaculture nets underwater and the charging station using coils for wireless power supply. This robot and a charging station will be installed on the aquaculture nets, and the robot will be driven periodically to clean the nets underwater with less labor and in a safe manner.
Creators : Fujiwara Shinpei Publishers : National Fisheries University Updated At : 2023-06-14 13:53:39
Journal of National Fisheries University Volume 71 Issue 1 pp. 11 - 20
published_at 2022-12
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.
Creators : Momota Kazuyuki | Doi Hiroyuki | Hashiguchi Yasuyuki | Sakai Harumi | Murakami Shoki | Obata Hiroshi Publishers : National Fisheries University Updated At : 2023-06-09 13:39:59
Journal of National Fisheries University Volume 71 Issue 1 pp. 1 - 9
published_at 2022-12
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.
Creators : Handa Takeshi | Araki Akira Publishers : National Fisheries University Updated At : 2023-06-08 16:49:07
Journal of National Fisheries University Volume 71 Issue 1 pp. 21 - 25
published_at 2022-12
An unusual instance of biting behavior by the pufferfish Arothron meleagris, possibly related to spawning behavior was observed during low tide of new moon spring tide while scuba-diving off the Maldives Islands. Multiple males were following, biting and clinging persistently to a female. Subsequent internet searches revealed that similar biting behavior was common among several congeners, possibly being a characteristic spawning-related behavior of the genus.
Creators : Doi Hiroyuki | Maei Kaori | Yoshitake Takafumi | Momota Kazuyuki | Sakai Harumi Publishers : National Fisheries University Updated At : 2023-06-09 14:11:55
Journal of National Fisheries University Volume 70 Issue 4 pp. 125 - 148
published_at 2022-03
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.
Creators : Kondo Masakazu | Yasumoto Shinya Publishers : National Fisheries University Updated At : 2022-06-24 16:09:00
Journal of National Fisheries University Volume 70 Issue 4 pp. 175 - 184
published_at 2022-03
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.
Creators : Hokimoto Ken Publishers : National Fisheries University Updated At : 2022-06-28 16:53:57
Journal of National Fisheries University Volume 70 Issue 4 pp. 149 - 163
published_at 2022-03
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.
Creators : Kondo Masakazu | Yasumoto Shinya Publishers : National Fisheries University Updated At : 2022-06-27 16:20:58
Journal of National Fisheries University Volume 70 Issue 4 pp. 115 - 123
published_at 2022-03
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.
Creators : Noda Mikio | Murase Noboru Publishers : National Fisheries University Updated At : 2022-06-24 14:15:55
Journal of National Fisheries University Volume 70 Issue 4 pp. 165 - 173
published_at 2022-03
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.
Creators : Yaguchi Shigenori | Fujinaka Megumi | Yoshida Haruka | Yamazaki Ryoutarou | Ohkubo Makoto | Maeda Toshimichi Publishers : National Fisheries University Updated At : 2022-06-28 14:42:32
Journal of National Fisheries University Volume 70 Issue 4 pp. 185 - 198
published_at 2022-03
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.
Creators : Daimaruya Miyuki Publishers : National Fisheries University Updated At : 2022-06-29 13:05:32
Journal of National Fisheries University Volume 70 Issue 3 pp. 91 - 100
published_at 2022-01
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.
Creators : Ohara Junichi | Ishida Masateru Publishers : National Fisheries University Updated At : 2022-06-23 16:32:44
Journal of National Fisheries University Volume 70 Issue 3 pp. 101 - 113
published_at 2022-01
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.
Creators : Ishida Takeshi | Ohara Junichi Publishers : National Fisheries University Updated At : 2022-06-23 16:52:22
Journal of National Fisheries University Volume 70 Issue 3 pp. 79 - 89
published_at 2022-01
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.
Creators : Fujiwara Shinpei Publishers : National Fisheries University Updated At : 2022-06-23 15:06:45
Journal of National Fisheries University Volume 70 Issue 3 pp. 69 - 77
published_at 2022-01
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.
Creators : Handa Takeshi | Araki Akira Publishers : National Fisheries University Updated At : 2022-06-23 14:35:20
Journal of National Fisheries University Volume 70 Issue 2 pp. 45 - 54
published_at 2021-12
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.
Creators : Ohta Hiromitsu | Takada Hirotomo | Fukui Ryousuke | Nagahashi Naoya | Yamada Yuta Publishers : National Fisheries University Updated At : 2022-06-22 16:34:27
Journal of National Fisheries University Volume 70 Issue 2 pp. 55 - 61
published_at 2021-12
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.
Creators : Abe Mahiko | Tara Chizuru | Fujiki Shinya | Kawasaki Shusaku | Murase Noboru Publishers : National Fisheries University Updated At : 2022-06-23 12:50:01