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A prominent large negative δ13Corg excursion and a coeval notable spike in mercury (Hg)/total organic carbon ratio are observed in the middle–upper Permian Gohan Formation in central Korea, located in the eastern Sino-Korean block (SKB), which may represent the Capitanian mass extinction event. The SKB was separated from the South China block by the eastern Palaeo-Tethys Ocean. This finding from the SKB supports the widespread Hg loading to the environment emitted from the Emeishan volcanic eruptions in SW China. This study demonstrates that the Hg cycle was globally perturbed in association with global carbon cycle perturbation that occurred during the Capitanian Extinction.
We trace Sn nanoparticles (NPs) produced from SnO2 nanotubes (NTs) during lithiation initialized by high energy e-beam irradiation. The growth dynamics of Sn NPs is visualized in liquid electrolytes by graphene liquid cell transmission electron microscopy. The observation reveals that Sn NPs grow on the surface of SnO2 NTs via coalescence and the final shape of agglomerated NPs is governed by surface energy of the Sn NPs and the interfacial energy between Sn NPs and SnO2 NTs. Our result will likely benefit more rational material design of the ideal interface for facile ion insertion.
The upper Palaeozoic succession (Pyeongan Supergroup) in central eastern Korea is well correlated with the equivalent successions distributed in North China, suggestive of the Korean upper Palaeozoic being part of the Sino-Korean Block. Detrital zircon U–Pb ages and Sm–Nd isotope compositions of the Pyeongan Supergroup in the Samcheok coalfield of the Taebaeksan Basin were analysed. A single predominant zircon age peak at c. 1.9 Ga (> 70%) is marked in all sedimentary units, followed by varying amounts of minor late Palaeozoic grains (up to 30%). The rarity of Meso- to Neoproterozoic- and Silurian-aged zircons confirms that sediment influx from the South China and Qinling blocks was insignificant. The 2.0–1.8 Ga-dominated zircon age pattern and the Nd isotope composition (average εNd(0) = −15.5±4.0) of the Pyeongan Supergroup most closely reflect the signature of the Yeongnam Massif basements, which supports a previous hypothesis that the Pyeongan Supergroup was mostly derived from a palaeo-orogen located to the east–southeast. Relatively higher εNd(0) values (> −10.1) in the lowermost and the upper parts of the succession are closely matched by the increased occurrence of syn-depositional-aged zircons, which indicates considerable mixing of juvenile materials at c. 320 Ma and 260 Ma. Both arc-related magmatic events are interpreted to have been related to oceanic subduction, suggesting that the eastern margin of the Sino-Korean Block was an active continental margin during late Palaeozoic times.
Devastating disasters around the world directly contribute to significant increases in human mortality and economic costs. The objective of this study was to examine the current state of the Korea Disaster Relief Team that participated in an international training module.
The whole training period was videotaped in order to observe and evaluate the respondents. The survey was carried out after completion of the 3-day training, and the scores were reported by use of a 5-point Likert scale.
A total of 43 respondents were interviewed for the survey, and the results showed that the overall preparedness score for international disasters was 3.4±1.6 (mean±SD). The awareness of the Incident Command System for international disasters was shown to be low (3.5±1.1). Higher scores were given to personnel who took on leadership roles in the team and who answered “I knew my duty” (4.4±0.6) in the survey, as well as to the training participants who answered “I clearly knew my duty” (4.5±0.5).
The preparedness level of the Korea Disaster Relief Team was shown to be insufficient, whereas understanding of the roles of leaders and training participants in the rescue team was found to be high. It is assumed that the preparedness level for disaster relief must be improved through continued training. (Disaster Med Public Health Preparedness. 2016;1–5)
Blackberry is a fruiting berry species with very high nutrient contents. With the recent increasing consumer demand for blackberries, new sources of germplasm and breeding techniques are required to improve blackberry production. This study was carried out to evaluate the genetic diversity (GD) and relationship among 55 blackberry (Rubus fruticosus) mutants derived from γ-ray treatment (52 lines) and N-methyl-N′-nitrosourea (MNU) treatment (three lines) using an inter-simple sequence repeat marker. A total of 18 bands were amplified with an average of 3.6 bands per primer. Among them, eight bands were identified to be polymorphic with a rate of 44.4%. In addition, the GD information content values were highest in the 60 Gy treatment population and the GD values were higher in the γ-ray treatment populations than in the MNU treatment population. According to a cluster analysis, all the mutant lines can be classified into five categories, and the genetic distance was greatest between the 80 Gy-irradiated population and other populations. These results indicate that mutant lines have high GD and can be effectively utilized for improving blackberry breeding.
Dynamic recrystallization (DRX) of 99.9999% aluminum single crystal at room temperature was examined under frictionless deformation mode. To exclude the self-heating of the specimen due to applied high strain, a microcrack that localizes the stress at a very small region was intentionally introduced by controlled local necking. For the in situ observation of DRX, a specially designed in situ microdeformation device was positioned inside an electron backscattered diffraction system chamber. Recrystallized grains showed relatively random texture and preferred growth direction. The subgrains with low-angle grain boundaries formed by dynamic recovery transformed into small grains with high-angle grain boundaries, acting as nuclei for discontinuous dynamic recrystallization and growing by further deformation. The DRX in pure aluminum can take place under frictionless tensile deformation conditions at room temperature, and the stress localization and high purity are key issues for the DRX of aluminum at room temperature.
The hardness changes caused by formation of the metastable and stable phases were examined and correlated with the microstructural changes in grain interior and grain boundary during aging at 350 °C to clarify the age-hardening and softening mechanism of a low-gold Au-Cu-Ag-Pd dental alloy. Aging in this context refers to the time-delay that occurs wherein such alloys are kept at elevated temperatures for periods upto many hours to allow precipitation or ordering to take place. During the period of increasing hardness, the matrix was separated into the Ag-rich α1 and AuCu I phases through the metastable phases, forming block-like structure. The apparent hardening was attributed primarily to lattice strain due to the tetragonality of AuCu I′ [the primer (′) here indicates a metastable phase; likewise (I) and (I′) indicate stable AuCu I and metastable AuCu I′ phases, respectively] and AuCu I phases along the c-axis, secondarily to the coherency or semicoherency strain between the metastable α1′ and AuCu I′ phases and between the α0 and AuCu I phases along the a-axis. The apparent softening was caused primarily by growth and coarsening of the lamellar structure in the grain boundaries, secondarily by coarsening of the block-like structure in the grain interior.
Geochemical characteristics of marine sediment from the southern Drake Passage were analyzed to reconstruct variations in sediment provenance and transport paths during the late Quaternary. The 5.95 m gravity core used in this study records paleoenvironmental changes during the last approximately 600 ka. Down-core variations in trace element, rare earth element, and Nd and Sr isotopic compositions reveal that sediment provenance varied according to glacial cycles. During glacial periods, detrital sediments in the southern Drake Passage were mostly derived from the nearby South Shetland Islands and shelf sediments. In contrast, interglacial sediments are composed of mixed sediments, derived from both West Antarctica and East Antarctica. The East Antarctic provenance of the interglacial sediments was inferred to be the Weddell Sea region. Sediment input from the Weddell Sea was reduced during glacial periods by extensive ice sheets and weakened current from the Weddell Sea. Sediment supply from the Weddell Sea increased during interglacial periods, especially those with higher warmth such as MIS 5, 9, and 11. This suggests that the influence of deep water from the Weddell Sea increases during interglacial periods and decreases during glacial periods, with the degree of influence increasing as interglacial intensity increases.
Recent extensive nanomechanical experiments have revealed that the instantaneous strength and plasticity of a material can be significantly affected by the size (of sample, microstructure, or stressed zone). One more important property to be added into the list of size-dependent properties is time-dependent plastic deformation referred to as creep; it has been reported that the creep becomes more active at the small scale. Analyzing the creep in the small scale can be valuable not only for solving scientific curiosity but also for obtaining practical engineering information about the lifetime or durability of advanced small-scale structures. For the purpose, nanoindentation creep experiments have been widely performed by far. Here we critically review the existing nanoindentation creep methods and the related issues and finally suggest possible novel ways to better estimate the small-scale creep properties.
Interspecies intracytoplasmic sperm injection has been carried out to understand species-specific differences in oocyte environments and sperm components during fertilization. While sperm aster organization during cat fertilization requires a paternally derived centriole, mouse and hamster fertilization occur within the maternal centrosomal components. To address the questions of where sperm aster assembly occurs and whether complete fertilization is achieved in cat oocytes by interspecies sperm, we studied the fertilization processes of cat oocytes following the injection of cat, mouse, or hamster sperm. Male and female pronuclear formations were not different in the cat oocytes at 6 h following cat, mouse or hamster sperm injection. Microtubule asters were seen in all oocytes following intracytoplasmic injection of cat, mouse or hamster sperm. Immunocytochemical staining with a histone H3-m2K9 antibody revealed that mouse sperm chromatin is incorporated normally with cat egg chromatin, and that the cat eggs fertilized with mouse sperm enter metaphase and become normal 2-cell stage embryos. These results suggest that sperm aster formation is maternally dependent, and that fertilization processes and cleavage occur in a non-species specific manner in cat oocytes.
Although electrical pacing is of great utility in many cardiovascular diseases, its effects on the combined cardiac cell therapy have not been established. We hypothesised that mesenchymal stem cell transplantation changes cardiac sympathetic nerve and gap junction, and concomitant pacing has additional biological effects.
We monitored cardiac rhythm for 4 weeks after human mesenchymal stem cell transplantation (1 × 107, epicardial injection) in 18 dogs in vivo, seven human mesenchymal stem cell with pacing, six human mesenchymal stem cell, and five sham, and evaluated the sympathetic innervation, nerve growth factor-β; tyrosine hydroxylase, angiogenesis, von Willebrand factor, and connexin43 expressions by real time (RT)–polymerase chain reaction and immunostaining. We also measured mRNA expressions of nerve growth factor-β, von Willebrand factor, and connexin43 in vitro culture of human mesenchymal stem cell with or without pacing.
Human mesenchymal stem cell transplanted hearts expressed higher mRNA of nerve growth factor-β (p < 0.01) with sympathetic nerves (p < 0.05), higher mRNA of von Willebrand factor (p < 0.001) with angiogenesis (p < 0.001), but lower mRNA of connexin43 (p < 0.0001) with reduced gap junctions (p < 0.001) than sham. Pacing with human mesenchymal stem cell transplantation resulted in higher expression of mRNA of connexin43 (p < 0.02) and gap junctions (p < 0.001) compared with sham. In contrast, in vitro paced mesenchymal stem cell reduced expression of connexin43 mRNA (p < 0.02).
Human mesenchymal stem cell transplantation increased cardiac sympathetic innervation and angiogenesis, but reduced gap junction after transplanted in the canine heart. In contrast, concomitant electrical pacing increased gap junction expression by paracrine action.