Lithospheric thinning and ignition of a Cordilleran magmatic flare-up:Geochemical and O-Hf isotopic constraints from Cretaceous plutons in southern Korea

Northeast Asian continental margins contain the products of magma emplacement driven by prolonged subduction of the(paleo-)Pacific plate.As observed in many Cordilleran arcs,magmatic evolution in this area was punctuated by high-volume pulses amid background periods.The present study investigates the early evolution of the Cretaceous magmatic flare-up using new and published geochronological,geochemical,and O-Hf isotope data from plutonic rocks in the southern Korean Peninsula.After a long(~50 m.y.)magmatic hiatus and the development of the Honam Shear Zone through flat-slab subduction,the Cretaceous flare-up began with the intrusion of monzonites,granodiorites,and granites in the inboard Gyeonggi Massif and the intervening Okcheon Belt.Compared to Jurassic granitoids formed during the former flare-up,Albian(~111 Ma)monzonites found in the Eopyeong area of the Okcheon Belt have distinctly higher zirconε_(Hf)(t)(-7.5±1.3)andδ^(18)O(7.78‰±0.25‰)values and lower wholerock La/Yb and Sr/Y ratios.The voluminous coeval granodiorite and granite plutons in the Gyeonggi Massif are further reduced in Sr/Y and to a lesser extent,in La/Yb,and have higher zirconε_(Hf)(t)values(-13 to-19)than the Precambrian basement(ca.-30).These chemical and isotopic features indicate that Early Cretaceous lithospheric thinning,most likely resulting from delamination of tectonically and magmatically overthickened lithospheric keel that was metasomatized during prior subduction episodes,and consequent asthenospheric upwelling played vital roles in igniting the magmatic flare-up.The O-Hf isotopic ranges of synmagmatic zircons from the Albian plutons and their Paleoproterozoic and Jurassic inheritance attest to the involvement of lithospheric mantle and crustal basement in magma generation during this decratonization event.Arc magmatism then migrated trenchward and culminated in the Late Cretaceous,yielding widespread granitoid rocks emplaced at shallow crustal levels.The early Late Cretaceous(94-85 Ma)granites now prevalent in Seoraksan-Woraksan-Sokrisan National Parks are highly silicic and display flat chondrite-normalized rare earth element patterns with deep Eu anomalies.Synmagmatic zircons in these granites mimic their host rock's chemistry.Delamination-related rejuvenation of crustal protoliths is indicated by zirconε_(Hf)(t)values of granites(-6 to-20)that are consistently higher than the Precambrian basement value.Concomitant core-to-rim variation in zircon O-Hf isotopic compositions reflects a typical sequence of crustal assimilation and fresh input into the magma chamber.

Anti-Proliferative Effects of Ginsenosides Extracted from Mountain Ginseng on Lung Cancer

Objective： To investigate the effect of three major ginsenosides from mountain ginseng as anti- cancer substance and explore the underlying mechanism involved in lung cancer. Methods： The inhibitory proliferation of lung cancer by major five ginsenosides （Rbl, Rb2, Rgl, Rc, and Re） was examined using 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide assay. Calculated 50% inhibition （IC50） values of five ginsenosides were determined and compared each other. Apoptosis by the treatment of single ginsenoside was performed by fluorescence-assisted cytometric spectroscopy. The alterations of apoptosis-related proteins were evaluated by Western blot analysis. Results： The abundance of ginsenosides in butanol extract of mountain ginseng （BX-MG） was revealed in the order of Rbl, Rgl, Re, Rc and Rb2. Among them, Rbl was the most effective to lung cancer cell, followed by Rb2 and Rgl on the basis of relative IC50 values of IMR90 versus A549 cell. The alterations of apoptotic proteins were confirmed in lung cancer A549 cells according to the administration of Rbl, Rb2 and Rgl. The expression levels of caspase-3 and caspase-8 were increased upon the treatment of three ginsenosides, however, the levels of caspase-9 and anti-apoptotic protein Bax were not changed. Conclusion： Major ginsenosides such as Rbl, Rb2 and Rgl comprising BX-MG induced apoptosis in lung cancer cells via extrinsic apoptotic pathway rather than intrinsic mitochondrial pathway.

UV light driven high-performance room temperature surface acoustic wave NH_(3) gas sensor using sulfur-doped g-C_(3)N_(4) quantum dots

Nanomaterials integrated surface acoustic wave(SAW)gas sensing technology has emerged as a promising candidate for realtime toxic gas sensing applications for environmental and human health safety.However,the development of novel chemical interface based on two-dimensional(2D)sensing materials for SAW sensors for the rapid and sensitive detection of NH_(3)gas at room temperature(RT)still remains challenging.Herein,we report a highly selective RT NH_(3)gas sensor based on sulfur-doped graphitic carbon nitride quantum dots(S@g-C_(3)N_(4)QD)coated langasite(LGS)SAW sensor with enhanced sensitivity and recovery rate under ultraviolet(UV)illumination.Fascinatingly,the sensitivity of the S@g-C_(3)N_(4)QD/LGS SAW sensor to NH_(3)(500 ppb)at RT is dramatically enhanced by~4.5-fold with a low detection limit(~85 ppb),high selectivity,excellent reproducibility,fast response/recovery time(70 s/79 s)under UV activation(365 nm)as compared to dark condition.Additionally,the proposed sensor exhibited augmented NH_(3)detection capability across the broad range of relative humidity(20%–80%).Such remarkable gas sensing performances of the as-prepared sensor to NH_(3)are attributed to the high surface area,enhanced functional groups,sulfur defects,UV photogenerated charge carriers,facile charge transfer in the S@g-C_(3)N_(4)QD sensing layer,which further helps to improve the gas molecules adsorption that causes the increase in conductivity,resulting in larger frequency responses.The gas sensing mechanism of S@g-C_(3)N_(4)QD/LGS SAW sensor is ascribed to the enhanced electroacoustic effect,which is supported by the correlation of resistive type and COMSOL Multiphysics simulation studies.We envisage that the present work paves a promising strategy to develop the next generation 2D g-C_(3)N_(4)based high responsive RT SAW gas sensors.