A lactic acid monomer has an asymmetric carbon in the molecule, so there are optical isomer l- and d-type. The most widely used poly(lactic acid) (PLA) for commercial applications is poly(l-lactic acid) (PLLA). PLLA is the polymerization product of l-lactide. Certain treatments of PLLA can yield a film that exhibits shear piezoelectricity. Thus, piezoelectric PLLA fiber can be generated by micro slitting piezoelectric PLLA films or by a melt spinning method. We prepared left-handed helical multi fiber yarn (S-yarn) and right-handed helical yarn (Z-yarn) using piezoelectric PLLA fiber. PLLA exhibited shear mode piezoelectricity, causing the electric polarity of the yarn surface to be reversed on the S-yarn and Z-yarn when tension was applied. An SZ-yarn was produced by combining the S-yarn and Z-yarn, and fabric was prepared using the SZ-yarn. This study demonstrated that the fabric has a strong antibacterial effect, which is thought to be due to the strong electric field between the yarns. The field is generated by a piezoelectric effect when the fabric was extended and contracted.

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For geochemical analysis such as stable isotope ratio, radiocarbon dating and minor element analysis for a single species of microfossils, a large number of specimens, is required. Collecting specimens one by one under a microscope requires enormous time and effort. In this study, we developed a device that automates these efforts and can be used without expert knowledge. Microfossils can be accurately classified and identified to taxonomic species level using deep learning, which is one of the learning methods of artificial intelligence (AI), and picked up using a micromanipulator installed in the microscope with an automated motorized X-Y stage. A prototype of the classification model AI-PIC_20181024 showed the ability to classify microfossil species Cycladophora davisiana and Actinomma boreale (radiolarians) with accuracy exceeding 90% at a confidence level > 0.90. Using this method, it is possible to collect a large number of particles with speed and accuracy that cannot be achieved by a human technician. Although this technology can only be used for specific species of microfossils, it greatly reduces the hand work of picking and also enables chemical analysis, such as isotope ratio and minor element analysis, for small microfossil species for which it had been difficult to collect enough specimens. In addition to microfossils, this technology can be applied to other particles, with applications expected in various fields, such as medical, food, horticulture, and materials.

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To understand the role of the eyestalk neurosecretory system in regulation of larval morphogenesis, we performed eyestalk ablation on swimming crab Portunus trituberculatus larvae at various times during zoeal development. We measured the length of the chelae and pleopods, which become enlarged during development, and the dorsal spine and telson furcae, which are resorbed during metamorphosis in the final (fourth) stage zoeae and subsequent larval stages, including a supernumerary fifth stage zoeae and megalopae (fifth-instar larvae). The length of the chela and pleopod of fourth stage zoeae decreased when the bilateral eyestalks were ablated earlier during development. Eyestalk ablation had little effect on the zoeal dorsal spine and furcae. In fifth-instar larvae, the effects of eyestalk ablation changed radically depending on the time when the ablation was performed, and a critical period during the premoult of the third zoeal stage was identified. Ablation before this period caused retention of a large dorsal spine and furcae and resulted in moult to the supernumerary fifth zoeal stage. Ablation after this period allowed larvae to metamorphose into normal megalopae. Ablation during this period resulted in megalopae with immature morphology, whereby the larvae retained small dorsal spines and telson furcae. The results demonstrated that the eyestalk neurosecretory system most likely regulates larval morphogenesis during metamorphosis in 2 ways: the morphogenesis of body parts that are enlarged are continuously controlled throughout the zoeal stages, whereas the resorption of body parts is controlled instantaneously at a critical point during the premoult of the third zoeal stage.KEY WORDS: Larval morphogenesis · Larval metamorphosis · Morphological abnormality · Mass mortality in seed production · Moult-death syndrome OPEN PEN

The occurrence of morphologically immature megalopae, which retain zoeal features such as dorsal spines and furcae of telson, is closely correlated with larval mass mortality during seed production of the swimming crab Portunus trituberculatus in Japanese hatcheries. To determine the cause of immature megalopal morphology, zoeae were reared with various supplementary schedules and density of diets (rotifer, Artemia and phytoplanktons including Chlorella vulgaris and Nannochloropsis oculata). In addition, to assess the relationship between immature morphology and endocrine control, the effect of causative dietary factor was compared with the effect of eyestalk ablation at various timing during zoeal development. Megalopal immature morphology was more distinct in Chlorella‐supplemented groups than in Nannochloropsis‐supplemented groups. High density Chlorella supplementation was associated with the highest incidence of immaturity and resulted in larval mass mortality. The premoult of the third zoeal stage was identified as a critical period at which Chlorella supplementation led to the highest incidence of immaturity. This critical period coincided with the critical period at which larval metamorphosis was regulated by the eyestalk neurosecretory system. Our results suggested that the occurrence of immature megalopal morphology under culture conditions is most likely caused by phytoplankton (especially, Chlorella) supplementation, which disrupts the endocrine regulation. On the basis of our results, we successfully prevented the occurrence of immature megalopal morphology in 500 L tanks by excluding the influence of phytoplankton before the critical period (i.e. discontinuing phytoplankton supplementation and supplying rotifer cultured with non‐phytoplankton materials).

This paper presents a selection of the eutectic systems in the Al 2 O 3 -Y 2 O 3 -ZrO 2 pseudo-ternary system and the production of the undercooled melt due to melting of the metastable eutectic structure at the metastable eutectic temperature. In the pseudo-ternary system, there are two eutectic systems; one is the Al 2 O 3 -YAG(Y 3 Al 5 O 12 )-ZrO 2 equilibrium system and the other is the Al 2 O 3 -YAP(YAlO 3 )-ZrO 2 metastable system. The eutectic system was selected by maximum melt temperature before solidification. YAG nucleation was inhibited in the melt when heated above 2250 K and consequently the metastable eutectic solidification path was selected. The selection controlled by the melt temperature before solidification was similar to that of the Al 2 O 3 -Y 2 O 3 system. Furthermore, the undercooled melt formation was found when the Al 2 O 3 -YAP-ZrO 2 metastable eutectic structure was heated up to temperatures above the metastable eutectic temperature. The addition of ZrO 2 to the Al 2 O 3 -Y 2 O 3 system inhibited the YAG nucleation remarkably and enhanced the undercooled melt formation in comparison with the Al 2 O 3 -Y 2 O 3 pseudo-binary system. Ease of the undercooled melt formation in the pseudo-ternary system will be beneficial for the melt shaping processes.

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