Open Library Archives of Kagawa University (OLIVE)
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Convergence zones of coastal waters as hotspots for floating microplastic accumulation
No full text本論では、潮目のマイクロプラスチック（MP）密度が一般海域の40〜300倍高く、高松沖は、最大18.8個/m³に達することを発見した。この結果は、潮目が局所的なMPホットスポットとなる可能性を示唆している。潮目は稚魚の住みかでもあり、今後のさらなる研究が求められる。This study examines microplastic (MP, 1–5 mm) densities in convergence zones in a coastal sea, the Seto Inland Sea, comparing them to those of non-convergence zones and other areas. Notably, Seto convergence zones exhibit MP densities 40 to 300 times higher than non-convergence zones, with an extraordinary density of 3.7 ± 6.3 pieces m−3, similar to densities found in Tokyo Bay as known a MP hotspot. The predominant polymer found was expanded polystyrene, varying seasonally and peaking in summer. Juvenile fish associated with driftweed in these convergence zones face a risk of long-term MP exposure, potentially up to four months. This large number of MPs found in coastal convergence zones is similar to accumulation zones formed in the gyres of open oceans, with strong implications for detrimental effects on coastal marine life. However, these MPs are autochthonous, and may be manageable through local marine plastic waste management.journal articl
Mesocrystalline SrTiO3/CaTiO3 nanocomposites with 3D heteroepitaxial interfaces, superior piezoresponse and high Curie temperature
No full textFerroelectric mesocrystalline nanocomposites are promising piezoelectric nanomaterials due to the presence of three-dimensional (3-D) heteroepitaxial interfaces, rendering superior piezoelectric and dielectric responses due to lattice strain at the interface. Herein, we describe the synthesis of mesocrystalline SrTiO3/CaTiO3 (ST/CT) nanocomposites via a two-step topochemical process by using layered titanate H1.07Ti1.73O4·nH2O (HTO), as a precursor, and demonstrate the influence of synthesis parameters on nanostructure, morphology, piezoelectric response and dielectric behavior. The mesocrystalline ST/CT nanocomposites are formed by in-situ topotactic structural transformation, consisting of [110]-oriented ST nanocrystals and [001]-oriented CT nanocrystals with high-density 3-D heteroepitaxial interfaces. The presence of 3-D heteroepitaxial interfaces introduces lattice strain at the interface, leading to an enormously enhanced piezoelectric response with a d33* value of 301 p.m./V. Moreover, the Curie temperature of ST phase is significantly increased from −250 °C to 300 °C by introducing lattice strain. It is demonstrated that the piezoresponse depends on lattice mismatch at heteroepitaxial interfaces and optimal lattice mismatch is found to be ∼3.3%, where the largest lattice strain effect and an expected d33* value of about 450 p.m./V could be achieved. These results demonstrate the potential of lattice strain engineering for high-performance lead-free piezoelectric materials.journal articl
Regulation of nitric oxide by phytoglobins in Lotus japonicus is involved in mycorrhizal symbiosis with Rhizophagus irregularis
No full textVarious reactive molecular species are generated in plant–microbe interactions, and these species participate in defense and symbiotic responses. Leguminous plants successfully establish symbiosis by maintaining an appropriate level of nitric oxide (NO), which is generated in the roots and nodules during root nodule symbiosis. Phytoglobin (plant hemoglobin) controls NO levels in plants. In this study, we investigated mycorrhizal symbiosis, which occurs in more than 80% of land plants, between Rhizophagus irregularis and Lotus japonicus to clarify the involvement of phytoglobin-mediated NO regulation. The mycorrhizae of L. japonicus exhibited higher NO levels in the presence of R. irregularis than in its absence, especially at the infection site. LjGlb1–1, a phytoglobin that regulates NO level in L. japonicus, was upregulated during symbiosis with R. irregularis. In transformed hairy roots carrying the ProLjGlb1–1:GUS construct, LjGlb1–1 expression was observed at the R. irregularis infection site. We further examined the symbiotic phenotypes of L. japonicus lines with high and low LjGlb1–1 expression with R. irregularis. During mycorrhizal symbiosis, the high LjGlb1–1 expression line exhibited better growth than the wild-type, whereas the low expression line exhibited poor growth. In addition, the expression of LjPT4, a phosphate transporter specific to mycorrhizal symbiosis, was higher in the high LjGlb1–1 expression line, whereas that of the tubulin gene of R. irregularis was lower in the low LjGlb1–1 expression line than in the wild-type. These results confirm that NO regulation by LjGlb1–1 is involved in mycorrhizal symbiosis in L. japonicus, as it is reportedly in nitrogen-fixing symbiosis.journal articl
Immunohistochemical localization of HCA1 receptor in placenta in presence of fetal growth restriction
No full textIntroduction
Glucose metabolism produces lactate and hydrogen ions in an anaerobic environment. Fetuses with intrauterine growth restriction are considered to become progressively lactacidemic as well as hypoxic. Roles of lactate in the placenta in the presence of fetal growth restriction (FGR) remain to be clarified.Methods
Immunohistochemical localization of lactate-related substances, such as a receptor for lactate (hydroxy-carboxylic acid 1 receptor (HCA1 receptor/GPR81)), monocarboxylate transporters (MCTs) for lactate, lactate dehydrogenases (LDHs), and proteins expressed in syncytiotrophoblasts or cytotrophoblasts was examined in placentas of appropriate weight for gestational age (AGA) fetus and those showing FGR.Results
Immunoreactivity for the HCA1 receptor was present in the cytoplasm of some trophoblasts, predominantly localized to their basal (fetus-facing) side, and was frequently colocalized with that for E-cadherin or serine peptidase inhibitor, Kunitz type 1 (SPINT1), a marker protein of cytotrophoblasts. Immunoreactivity for MCT1 and MCT4 was present on the basal and the microvillous (maternal-facing) membranes of trophoblasts in both groups, respectively. Clear immunoreactivity for LDHA and LDHB was also observed in the cytoplasm of trophoblasts, mainly localized to their basal side. However, there were no significant differences in immunohistochemically stained areas of lactate-related substances between AGA and late-onset FGR groups. On the other hand, there were correlations between coefficients of the presence of chorioamnionitis and the values of LDHB and E-cadherin.Discussion
Immunohistochemical localization of the HCA1 receptor was predominantly observed in the cytoplasm located on the basal side of trophoblasts, suggesting a role of lactate in human placental development, including syncytialization.journal articl
Carrier transport and mesomorphic properties of deformable fluorinated perylene bisimide bearing disiloxane chains
No full textWe synthesized liquid crystalline difluorinated perylene bisimide derivatives bearing oligosiloxane moieties. At room temperature, these compounds exhibited columnar phases which were stabilized thermodynamically, compared to that of a non-fluorinated analog. The absorption bands in the thin films of the fluorinated compounds exhibited a slight bathochromic shift compared to that in the solution state, indicating a weak electronic coupling between the fluorinated perylene bisimide cores in the columnar phases. The electron mobilities in the columnar phases of the difluorinated compounds were determined to be on the order of 10−2 cm2V−1s−1 at room temperature by the time-of-flight measurements. The LUMO levels of the difluorinated compounds were lowered by 0.1 eV from that of non-fluorinated analog. Anion radicals of the fluorinated compounds were stable as that of the non-fluorinated analog while dianions of the fluorinated compounds were unstable unlike that of the non-fluorinated analog. The difluorinated compounds was soft waxy solid. In particular, the 1,7-difluorinated derivative is deformable to form various shapes at room temperature. A study on the surface morphology of the thin film indicated formation of microscopic grooves, which should enhance the softness of the compound.journal articl
Underwater fatigue behavior of cementitious mortar and a countermeasure using a water-dispersible polyurethane ether–Portland cement composite
No full textThe underwater fatigue behaviors of cementitious mortars are investigated with a focus on the mechanisms contributing to the deterioration of bridge foundations and possible countermeasures. This study analyzes the effects of water penetration during repetitive loading and unloading on the underwater fatigue lives of cementitious materials, highlighting the importance of considering dynamic water motion, in addition to the surface energy mechanism. Water penetration during underwater fatigue occurs even in water-saturated specimens, and water in- and egress within a few millimeters of the specimen surface can significantly reduce the fatigue life. This study proposes a novel approach using a water-dispersible polyurethane ether–Portland cement composite as a countermeasure to improve underwater fatigue resistance. Based on experimental analysis of fatigue in water and microstructural investigations of the composite, the presence of polyurethane compounds within the nano-to-micron-sized microstructures may mitigate water penetration and contribute to a corresponding increase in underwater fatigue life.journal articl
