A metal‐ and oxidant‐free electrochemical method for preparing selenomethyl‐substituted cyclic ethers or lactones via difunctionalization of olefines is presented. A series of ...selenomethyl‐substituted cyclic ethers, particularly 9‐ and 11‐ membered, selenomethyl‐substituted lactones (4‐6 membered), and selenomethyl‐substituted phthalides can be obtained via this reaction. This method features convenient operation, an electron as oxidant, and ammonium iodide as electrolyte, thereby making it a green synthesis method.
This paper realizes the evaluation and optimal decision of the spoofing effect on the global navigation satellite system (GNSS) under navigation countermeasures based on the game perspective, to ...overcome the limitations of current relevant research findings and maintain the secure application of the GNSS and maximize its defensive benefit during countering. An evaluation system based on the perspective of the game between spoofing strategies and defense measures is created to build the benefit matrix, which can solve the limitation in building a benefit matrix (the vital element in a game) that conforms to the confrontation‐oriented GNSS spoofing properties. Based on the built benefit matrix, a method integrating the grey expert‐based system with the hybrid evolutionary method is developed to realize quantifying the matrix and further make the optimal decision stably, which can solve the uncertainties of qualitative indices during quantifying and no global optimal solution for benefit equations deduced from the quantified matrix. Finally, based on various judgment principles, simulation and testing results verify the effectiveness of the obtained results and the superiority of the proposed method by comparing the results solved by the method in this paper with the results obtained by other decision‐making processing methods.
This paper realizes the evaluation and optimal decision of the spoofing effect on the global navigation satellite system (GNSS) under navigation countermeasures based on the game perspective, to overcome the limitations of the current relevant research findings and maintain the secure application of the GNSS and maximize its defensive benefit during countering. Specifically, it proposes and verifies a method related to the effective evaluation and dynamic decision of GNSS spoofing effect under the satellite navigation confrontation, it selects and updates the optimal defense measure according to the known spoofing strategies under different information conditions, and it minimizes the damage to GNSS. In conclusion, the safety protection ability of GNSS can be enhanced.
•Spatial–temporal variations of Mesozoic volcanic rocks in NE China are studied.•Transformation from the Paleo-Asian Ocean to circum-Pacific regimes happened during T3 to J1.•Temporal effect of the ...Mongol–Okhotsk belt on NE China extended from at least J1 to K11.•K12 and K2 volcanisms in NE China were related to the subduction of the Paleo-Pacific Plate.
LA-ICP-MS zircon U–Pb ages and geochemical data are presented for the Mesozoic volcanic rocks in northeast China, with the aim of determining the tectonic settings of the volcanism and constraining the timing of the overprinting and transformations between the Paleo-Asian Ocean, Mongol–Okhotsk, and circum-Pacific tectonic regimes. The new ages, together with other available age data from the literature, indicate that Mesozoic volcanism in NE China can be subdivided into six episodes: Late Triassic (228–201Ma), Early–Middle Jurassic (190–173Ma), Middle–Late Jurassic (166–155Ma), early Early Cretaceous (145–138Ma), late Early Cretaceous (133–106Ma), and Late Cretaceous (97–88Ma). The Late Triassic volcanic rocks occur in the Lesser Xing’an–Zhangguangcai Ranges, where the volcanic rocks are bimodal, and in the eastern Heilongjiang–Jilin provinces where the volcanics are A-type rhyolites, implying that they formed in an extensional environment after the final closure of the Paleo-Asian Ocean. The Early–Middle Jurassic (190–173Ma) volcanic rocks, both in the Erguna Massif and the eastern Heilongjiang–Jilin provinces, belong chemically to the calc-alkaline series, implying an active continental margin setting. The volcanics in the Erguna Massif are related to the subduction of the Mongol–Okhotsk oceanic plate beneath the Massif, and those in the eastern Jilin–Heilongjiang provinces are related to the subduction of the Paleo-Pacific Plate beneath the Eurasian continent. The coeval bimodal volcanic rocks in the Lesser Xing’an–Zhangguangcai Ranges were probably formed under an extensional environment similar to a backarc setting of double-direction subduction. Volcanic rocks of Middle–Late Jurassic (155–166Ma) and early Early Cretaceous (145–138Ma) age only occur in the Great Xing’an Range and the northern Hebei and western Liaoning provinces (limited to the west of the Songliao Basin), and they belong chemically to high-K calc-alkaline series and A-type rhyolites, respectively. Combined with the regional unconformity and thrust structures in the northern Hebei and western Liaoning provinces, we conclude that these volcanics formed during a collapse or delamination of a thickened continental crust related to the evolution of the Mongol–Okhotsk suture belt. The late Early Cretaceous volcanic rocks, widely distributed in NE China, belong chemically to a low- to medium-K calc-alkaline series in the eastern Heilongjiang–Jilin provinces (i.e., the Eurasian continental margin), and to a bimodal volcanic rock association within both the Songliao Basin and the Great Xing’an Range. The volcanics in the eastern Heilongjiang–Jilin provinces formed in an active continental margin setting related to the subduction of the Paleo-Pacific Plate beneath the Eurasian continent, and the bimodal volcanics formed under an extensional environment related either to a backarc setting or to delamination of a thickened crust, or both. Late Cretaceous volcanics, limited to the eastern Heilongjiang–Jilin provinces and the eastern North China Craton (NCC), consist of calc-alkaline rocks in the eastern Heilongjiang–Jilin provinces and alkaline basalts in the eastern NCC, suggesting that the former originated during subduction of the Paleo-Pacific Plate beneath the Eurasian continent, whereas the latter formed in an extensional environment similar to a backarc setting. Taking all this into account, we conclude that (1) the transformation from the Paleo-Asian Ocean regime to the circum-Pacific tectonic regime happened during the Late Triassic to Early Jurassic; (2) the effect of the Mongol–Okhotsk suture belt on NE China was mainly in the Early Jurassic, Middle–Late Jurassic, and early Early Cretaceous; and (3) the late Early Cretaceous and Late Cretaceous volcanics can be attributed to the subduction of the Paleo-Pacific Plate beneath the Eurasian continent.
Zircon U–Pb dating and whole-rock geochemical analysis have been undertaken on Late Paleozoic–Early Mesozoic intrusive rocks of central Jilin Province, NE China, with the aim of constraining the ...tectonic evolution of the eastern segment of the northern margin of the North China Block (NCB) during the Late Paleozoic–Early Mesozoic. Zircon U–Pb dating indicates that Late Paleozoic–Early Mesozoic magmatic events can be subdivided into four stages: Middle Permian (~270Ma), Late Permian (259–255Ma), Early Triassic (~249Ma), and Late Triassic (~222Ma). The Middle Permian magmatic event formed peraluminous garnet-bearing monzogranites, indicative of formation under a compressional tectonic regime related to collision between the NCB and the Songnen–Zhangguangcai Range Massif. The Late Permian magmatic event formed gabbros and syenogranites, a bimodal association that is typical of magmatism within post-collisional extensional setting. The Early Triassic magmatic event formed adakitic monzogranites, suggesting that they formed from magmas derived from partial melting of a thickened mafic lower crust. The Late Triassic magmatic event formed a series of mafic–ultramafic intrusive rocks, together with coeval granitoids in adjacent regions, and make up a typical bimodal association suggesting that they formed under an extensional environment related to the final amalgamation of the NCB and the Songnen–Zhangguangcai Range Massif. Taken together, we conclude that the northern margin of the NCB underwent multiple orogenic events between the Middle Permian and the Late Triassic, with final amalgamation of the NCB and the Songnen–Zhangguangcai Range Massif occurring in the Early Triassic, an event that led to the final suturing of the Solonker–Xra Moron–Changchun zone.
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•P2–T3 magmatism in the study area can be subdivided into four stages.•P2 garnet-bearing and T1 adakitic monzogranites reveal twice orogenic processes.•P3 and T3 bimodal magmatism reveals twice post-orogenic extensional settings.•T1 adakitic magmatism marks the final closure of the Paleo-Asian Ocean.
It has been anticipated that learning from nature photosynthesis is a rational and effective way to develop artificial photosynthesis system, but it is still a great challenge. Here, we assembled a ...photoelectrocatalytic system by mimicking the functions of photosystem II (PSII) with BiVO4 semiconductor as a light harvester protected by a layered double hydroxide (NiFeLDH) as a hole storage layer, a partially oxidized graphene (pGO) as biomimetic tyrosine for charge transfer, and molecular Co cubane as oxygen evolution complex. The integrated system exhibited an unprecedentedly low onset potential (0.17 V) and a high photocurrent (4.45 mA cm–2), with a 2.0% solar to hydrogen efficiency. Spectroscopic studies revealed that this photoelectrocatalytic system exhibited superiority in charge separation and transfer by benefiting from mimicking the key functions of PSII. The success of the biomimetic strategy opened up new ways for the rational design and assembly of artificial photosynthesis systems for efficient solar-to-fuel conversion.
The proline-type organocatalysts has been efficiently employed to catalyze a wide range of asymmetric transformations; however, there are still many synthetically useful and challenging ...transformations that remain unachievable in an asymmetric fashion. Herein, a chiral bifunctional organocatalyst with a spirocyclic pyrrolidine backbone-derived containing fluoro-alkyl and aryl sulfonamide functionalities, are designed, prepared, and examined in the asymmetric Mannich/acylation/Wittig reaction sequence of 3,4-dihydro-β-carboline with acetaldehyde, acyl halides, and Wittig reagents. As a result, the spirocyclic pyrrolidine trifluoromethanesulfonamide catalyst can facilitate this versatile sequence as demonstrated by 18 examples displaying excellent enantioselectivity (up to 94% ee), as well as moderate to good yields (up to 54% over 3 steps). As a practical application, the asymmetric total synthesis of naucleofficine I (1a) and II (1b) in ten steps have been accomplished.
The migration of hepatic stellate cells (HSCs) is essential to the hepatic fibrotic response, and recently High-mobility group box 1 (HMGB1) has been shown up-regulated during liver fibrosis. ...Nevertheless, whether HMGB1 can modulate the proliferation and migration of HSCs is poorly understood, as well as the involved intracellular signaling. In this study, we examined the effect of HMGB1 on proliferation, migration, pro-fibrotic function of HSCs and investigated whether toll-like family of receptor 4 (TLR4) dependent signal pathway is involved in the intracellular signaling regulation.
Modified transwell chamber system to mimic the space of Disse was used to evaluate the migration of human primary HSCs, and the protein expressions of related signal factors were evaluated by western blot. Cell proliferation was analyzed by MTT assay, the pro-fibrotic functions of HSCs by qRT-PCR and ELISA respectively. Recombinant human HMGB1 could significantly promote migration of HSCs under both haptotactic and chemotactic stimulation, especially the latter. Human TLR4 neutralizing antibody could markedly inhibit HMGB1-induced migration of HSCs. HMGB1 could enhance the phosphorylation of JNK and PI3K/Akt, and TLR4 neutralizing antibody inhibited HMGB1-enhanced phosphorylation of JNK and PI3K/Akt and activation of NF-κB. JNK inhibitor (SP600125) and PI3K inhibitor (LY 294002) significantly inhibited HMGB1-induced proliferation and migration of HSCs, and also reduced HMGB1-enhanced related collagen expressions and pro-fibrotic cytokines production.
HMGB1 could significantly enhance migration of HSCs in vitro, and TLR4-dependent JNK and PI3K/Akt signal pathways are involved in the HMGB1-induced proliferation, migration and pro-fibrotic effects of HSCs, which indicates HMGB1 might be an effective target to treat liver fibrosis.
To constrain the Permian–Early Mesozoic tectonic evolution of the eastern segment of the Paleo-Asian Ocean, we conducted zircon U–Pb dating and whole-rock geochemical analyses on six middle ...Permian–Middle Triassic intrusive plutons in central–eastern Jilin Province, NE China. Zircons from the six plutons display distinct oscillatory zoning and striped absorption in cathodoluminescence (CL) images, and Th/U ratios of 0.11–1.41, indicating a magmatic origin. Zircon U–Pb dating indicates that the intrusive rocks formed in the middle Permian (ca. 260Ma) to Middle Triassic (ca. 245Ma). In central–eastern Jilin Province, the middle Permian and Middle Triassic plutons are composed mainly of strongly deformed monzogranites with affinities to adakitic rocks, which are formed from partial melting of thickened mafic lower crust. In contrast, the late Permian–the Early Triassic plutons in central–eastern Jilin Province consist of a bimodal association (including gabbros and granitoids) and deformed monzonites, which typically form in extensional settings. These observations, along with the results of previous studies on early–middle Permian granitoids in western Jilin Province, indicate that the eastern segment of the Paleo-Asian Ocean underwent the initial closure in central–western Jilin Province during the middle Permian and the final closure in eastern Jilin Province in the Middle Triassic.
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•P2–T2 magmatisms are recognized in the eastern segment of the CAOB.•P2 and T2 adakitic rocks formed by partial melting of thickened crust.•P3–T1 bimodal magmatism formed in post-collisional extensional setting.•The final closure of the Paleo-Asian Ocean happened during Middle Triassic.
LA-ICP-MS zircon U–Pb dating and geochemical data have been obtained from five representative mafic–ultramafic intrusions in the Lesser Xing'an–Zhangguangcai Range, NE China, with the aim of ...improving our understanding of the Mesozoic tectonic evolution in the region, and in particular, determining the time of initiation of the circum-Pacific tectonic system. The selected zircons exhibit striped absorption in cathodoluminescence (CL) images and have high Th/U ratios (0.20–3.16), indicating a magmatic origin. The zircon U–Pb dates indicate that most of these magmatic zircons (other than a few relics that were captured and entrained in the magma) formed in the late Early Jurassic (186–182Ma), and not as previously supposed in the Middle Caledonian. The five mafic–ultramafic plutons are composed of olivine-gabbro, hornblendite, gabbro, hornblende-gabbro, and gabbro–diorite. The olivine-gabbro and hornblendite display cumulate textures, implying that fractional crystallization of olivine and plagioclase took place during magma evolution. These mafic–ultramafic igneous rocks have SiO2=37.3%–55.7%, MgO=3.05%–13.3%, Al2O3=11.8%–23.8%, Mg#=42–69 Mg#=100Mg/(Mg+Fe2+total), and δEu=0.88–1.32, and they display three types of rare earth element (REE) distribution patterns: right-slipped, flat patterns, or dome-like. The trace element spider diagrams show that the rocks are enriched in large ion lithophile elements (LILEs) such as Ba, K, and Sr, and depleted in high field strength elements (HFSEs) such as Nb, Ta, Zr, and Hf. The zircons have εHf (186–182Ma)=+2.7 to +12.0, and TDM1=366–732Ma. The geochemical data indicate that the Early Jurassic mafic magma originated in an extensional environment from the partial melting of a depleted mantle wedge that had been metasomatized by fluids released from a fossil subducted slab. These data, combined with information on the spatial variation of coeval igneous rocks, indicate that the formation of the Early Jurassic mafic–ultramafic rocks in the Lesser Xing'an–Zhangguangcai Range was related to the subduction of the Paleo-Pacific Plate beneath the Eurasian continent, and this event would mark the beginning of the circum-Pacific tectonic system.
► The mafic–ultramafic intrusive rocks are studied in NE China. ► The mafic–ultramafic intrusive rocks formed in Early Jurassic. ► They were derived from partial melting of a depleted mantle wedge within a fossil subduction zone. ► Early Jurassic mafic magmatism marks the beginning of the circum-Pacific tectonic system.
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