19 research outputs found
Data for: Mineralogical and Isotopic Constraints on Early, High-Temperature Events and Reservoirs Recorded in the Interior of a Type B Ca-Al-Rich Inclusion from the Reduced CV3 Chondrite Vigarano
No full textData in the manuscript entitled "Mineralogical and Isotopic Constraints on Early, High-Temperature Events and Reservoirs Recorded in the Interior of a Type B Ca-Al-Rich Inclusion from the Reduced CV3 Chondrite Vigarano", by Han J., Park C., Liu M.-C, Matsuda N., Simon J. I., and Keller L. P
MICROSTRUCTURAL CONSTRAINTS ON THE FORMATIONAL AND THERMAL HISTORIES OF REFRACTORY INCLUSIONS IN CO3 CHONDRITES
No full textRefractory inclusions, calcium-aluminum-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs), of variable textures and mineralogies in CO3 chondrites have been investigated in detail using the focused ion beam (FIB) sample preparation technique combined with transmission electron microscopy (TEM) in order (1) to characterize the microstructures, compositions and textural relationships of their various constituent phases at the micrometer to nanometer scales and (2) to provide additional constraints on their formational and subsequent thermal histories both in the solar nebula and on their asteroidal parent bodies. In particular, refractory inclusions in CO3 chondrites are very fine-grained so that they are sensitive recorders of both primary formational and secondary alteration processes, which can only be adequately characterized by TEM. This work represents the first microstructural study of AOAs and CAIs from two CO3 chondrites, Allan Hills A77307 and Kainsaz. The microstructural and compositional characteristics of AOAs and CAIs in the pristine CO3.0 chondrite, Allan Hills A77307, provide evidence that various high-temperature condensation and gas-solid reactions occurred in the solar nebula under both equilibrium and disequilibrium conditions. Diverse gas-solid reactions reflect localized differences in the primary mineral assemblages in individual AOAs and CAIs that controlled reaction pathways. Despite large variations in their texture and mineralogy, mineralogically- and compositionally-zoned refractory components in AOAs, spinel-pyroxene CAIs and melilite-rich CAIs may have formed by a similar sequence of high-temperature condensation and gas-solid reactions, as follows; (1) the formation of the cores of the inclusions from primary equilibrium condensates (i.e., perovskite, spinel and melilite), (2) disequilibrium, probably short-lived reactions of the primary core minerals with a nebular gas under highly dynamic conditions, forming diopside with remarkably wide compositional ranges over submicrometer distances and (3) direct equilibrium condensation of pure diopside from a nebular gas, forming the outermost rim on the exterior of the inclusions. In spinel-hibonite CAIs, the crystallographic orientation relationships between spinel and hibonite provide evidence of the preferential epitaxial nucleation and growth of spinel on hibonite surfaces after hibonite condensation, rather than melilite. This process contributed to the rarity of melilite in this type of CAI. In the Kainsaz CO3.2 chondrite, the widespread, but heterogeneous occurrence of Fe enrichments at the outer margins of AOAs and along grain boundaries of olivines in AOAs provide evidence that mild parent body thermal metamorphism occurred at relatively low temperatures. However, due to incomplete textural and chemical equilibration of the whole rock, Kainsaz AOAs still retain primary nebular compositional and textural characteristics
Microstructures of Hibonite From an ALH A77307 (CO3.0) CAI: Evidence for Evaporative Loss of Calcium
No full textHibonite is a comparatively rare, primary phase found in some CAIs from different chondrite groups and is also common in Wark-Lovering rims [1]. Hibonite is predicted to be one of the earliest refractory phases to form by equilibrium condensation from a cooling gas of solar composition [2] and, therefore, can be a potential recorder of very early solar system processes. In this study, we describe the microstructures of hibonite from one CAI in ALH A77307 (CO3.0) using FIB/TEM techniques in order to reconstruct its formational history
Association between tropical cyclone exposure and changes in mortality in Korea: an application of two-stage generalized synthetic control approach
No full textInternational audienceBACKGROUND AND AIM[|]While the adverse health effects of natural disasters are gaining public interest, evidence regarding the mortality effects of tropical cyclones in Korea remains unclear. Therefore, utilizing detailed cyclone moving routes and cause-specific mortality data in fine administrative units of Korea, this study evaluated the mortality effects of cyclone exposure using a natural-experiment framework[¤]METHOD[|]Region (si, gun, gu administrative units) specific mortality data (all, non-accidental, cardiovascular, cancer, respiratory, accidental mortality) and cyclone data (size, moving route, storm and wind range) from 2002 to 2023 were obtained from the governmental database. Generalized synthetic control analysis coupled with random effect model meta-analysis were used to estimate the average mortality effect of tropical cyclone exposure during the two weeks following the event in cyclone exposed region. Stratification analyses were conducted for age-groups, educational levels, and location of deaths.[¤]RESULTS[|]Among the 21 cyclones that made landfall on the Korean peninsula, nine tropical cyclones (2007 Nari, 2010 Dianmu, 2010 Kompasu, 2012 Khanun, 2012 Tembin, 2016 Chaba, 2019 Mitag, 2020 Jangmi, 2021 Omais) with clearly defined exposed and non-exposed regions were selected for analysis. During the two weeks following each cyclone, there was a daily average increase of 0.02% (95% CI: 0.01, 0.04) in all-cause mortality in cyclone-exposed region compared to non-exposed. Increasing trends were observed for cardiovascular, respiratory, and accidental mortalities. Regions near cyclone paths, elderly individuals, lower-educated groups, and deaths occurring outside medical facilities showed a more significant increase.[¤]CONCLUSIONS[|]There was a clear increase in mortality in cyclone-exposed regions in Korea. Further investigation into vulnerable populations and changes in hospital utilization following cyclones is warranted
Analysis of Stiffness Effect on Valve Behavior of a Reciprocating Pump Operated by Piezoelectric Elements
No full textThis study analyzed the characteristics of a small reciprocating pump with a cantilever valve driven by a piezo actuator. Three types of valves were fabricated to investigate the effect of the valve stiffness on the pump performance and to measure the variation in the flow rate according to the frequency. The flow rate increased with the driving frequency until a certain frequency was reached, and then it started to decrease. The rise in the pressure of the pump was found to increase as the stiffness decreased. The pump performance could be clearly distinguished according to the stiffness of the valve. The observation of the valve movements revealed that the valve opening time did not change regardless of the operating frequency, but it changed with the valve stiffness. The delay in time for the outlet valve increased significantly with an increase in the frequency. It seems that the overlap of the opening time of the inlet valve and the outlet valve plays an important role in pump performance. Therefore, it is advisable to use different designs for the inlet and outlet valves, where the shape and stiffness of the valve are adjusted
