The emotional contagion of netizens is an important factor that accelerates the spread of rumors, and it is also key to the effectiveness of rumor refutation. Based on the existing emotional model, ...we improved the method for calculating the emotional value and the transformation rules to simulate how the infection transforms individual emotion to group emotion during rumor refutation. The results show that the cycle and trend of netizen emotional change vary by period, but the final distribution structure presents a relatively stable state. The factors that affect the emotional changes of netizens are mainly objective and subjective aspects, both of which can promote the evolution of emotional contagion. The objective aspect depends on the speed and credibility of the rumor, and the subjective aspect depends on the degree of intimacy between netizens. After rumor refutation, emotions generally change from negative emotions to positive or immune emotions.
Age-associated changes in mitochondria are closely involved in aging. Apart from the established roles in bioenergetics and biosynthesis, mitochondria are signaling organelles that communicate their ...fitness to the nucleus, triggering transcriptional programs to adapt homeostasis stress that is essential for organismal health and aging. Emerging studies revealed that mitochondrial-to-nuclear (mito-nuclear) communication via altered levels of mitochondrial metabolites or stress signals causes various epigenetic changes, facilitating efforts to maintain homeostasis and affect aging. Here, we summarize recent studies on the mechanisms by which mito-nuclear communication modulates epigenomes and their effects on regulating the aging process. Insights into understanding how mitochondrial metabolites serve as prolongevity signals and how aging affects this communication will help us develop interventions to promote longevity and health.
Mito-nuclear communication plays an integral role in cellular homeostasis and aging.Mitochondrial metabolites are substrates or mediators of epigenetic modifications.Mitochondrial-to-nuclear stress signals modulate lifespan via epigenetic regulations.
The recent discovery of large porphyry copper deposits (PCDs) associated with Miocene (22–12 Ma) granitoid magmas in the eastern section of the Paleocene-Eocene Gangdese magmatic arc in the ...Himalaya-Tibetan orogenic belt raises new questions about the origin of water-rich (≥4.5 wt.%), oxidized (ΔFMQ 1–3) magmas in continental collisional settings and their mineralization potential. We review the literature and compile available data on whole rock and isotope geochemistry for Cenozoic igneous rocks from Tibet, and add new zircon Ce4+/Ce3+ and Ti-in-zircon thermometry data to better understand variations in oxidation state and thermal evolution of these suites, which are key controls on Cu mineralization. Six distinct Cenozoic igneous suites are defined: Paleocene-Eocene syn-collisional Gangdese magmatic arc rocks (ΔFMQ = −1.2 to +0.8) (suite I), and five broadly contemporaneous Miocene suites. A distinct change in magmatism along the length of the belt occurs at around 88°E in the Miocene suites: to the east, porphyry copper mineralization is associated with a moderately oxidized, high-Sr/Y granitoid suite (suite II, ΔFMQ = +0.8 to +2.9) with minor occurrences of transitional (hybrid) monzonitic (suite III) and trachytic rocks (suite IV; both with zircon Ce4+/Ce3+ > 50–100, EuN/EuN* = ~0.5, and ΔFMQ = ~+1 to +2). To the west of 88°E, trachytic volcanic rocks (suite V) are more voluminous but more reduced (zircon Ce4+/Ce3+ < 50, ΔFMQ < +1), and are associated with sparse, poorly mineralized high-Sr/Y granitoids (suite VI) which are moderately oxidized (zircon Ce4+/Ce3+ = 20–100, ΔFMQ = ~+1 to +3).
The Miocene high-Sr/Y granitoids have many compositional and isotopic similarities to the Paleocene-Eocene Gangdese arc rocks, and are interpreted to have been derived by melting of the hydrated arc root, with minor mantle input. In contrast, the highly evolved isotopic signatures of the Miocene trachytic rocks, combined with deep seismic profiles and a xenolith-derived geotherm, suggest their derivation from the underthrust Indian Proterozoic subcontinental lithospheric mantle (SCLM) or old fore-arc Tibetan SCLM during phlogopite breakdown at temperatures of ~1100°C.
Based on published geophysical data and tectonic reconstructions, we develop a model that explains the origin of the various Miocene magmatic suites, their spatial differences, and the origin of related PCDs. Following the early stages of continental collision (Eocene–Oligocene), shallow underthrusting of the Indian continental lithosphere and subcretion of Tethyan sediments (including oxidized carbonates and possibly evaporites) under eclogite facies conditions promoted the release of aqueous fluids, which hydrated and oxidized the base of the overlying Tibetan plate. This metasomatism rendered the Tibetan lower crust fusible and fertile for metal remobilization.
During the mid-Miocene, the Indian slab steepened in the eastern sector (east of ~88°E). In this eastern belt, deeply derived trachytic magmas were trapped in melt zones at the base of the Tibetan crust, and variably mixed with the crustally-derived, high Sr/Y granitoid magmas. They may also have released water that contributed to fluid-fluxed melting of the lower crust, producing voluminous high-Sr/Y granitoid magmas, which were associated with significant PCD mineralization. Hybridization between the trachytic magmas and lower crustal partial melts is indicated by intermediate isotopic compositions, enriched Cr and Ni contents, and high Mg# in some intermediate-to-felsic (56–70 wt. % SiO2) high-Sr/Y granitoids. Trapping of the trachytic melts in deep crustal melt zones explains the relatively small volumes of trachytic magmas erupted at surface in the east.
In contrast, to the west of ~88°E, subduction of the Indian plate has remained flat to the present day, preventing incursion of hot asthenosphere. Consequently, cooler conditions in the deep Tibetan lithosphere resulted in limited crustal melting and the production of only small volumes of high-Sr/Y granitic magmas. Trachytic melts ascending from the underthrust Indian or Tibetan plate were able to pass through the cooler lower crust and erupted in greater volume at surface, whereas only small volumes of high-Sr/Y granitoid magma were generated and are not associated with significant PCD mineralization.
Living cell‐based drug delivery systems (LC‐DDSs) are limited by adverse interactions between drugs and carrier cells, typically drug‐induced toxicity to carrier cells and restriction of carrier ...cells on drug release. Here, a method is established to adsorb nanocarriers externally to living cells, thereby reducing cytotoxicity caused by drug uptake and realizing improved drug release at the disease site. It is found that a divalent metal ion‐phenolic network (MPN) affords adhesion of poly (lactic‐co‐glycolic acid) nanoparticles onto macrophage (Mφ) surfaces with minimized intracellular uptake and no negative effect on cell proliferation. On this basis, an Mφ‐DDS with doxorubicin‐loaded nanoparticles on cell surface (DOX‐NP@Mφ) is constructed. Compared to intracellular loading via endocytosis, this method well‐maintains bioactivity (viability and migration chemotaxis) of the carrier cell. By virtue of the photothermal effect of MPN at the tumor site, DOX‐NP‐associated vesicles are liberated for improved chemotherapy. This facile, benign, and efficient method (ice bath, 2 min) for extracellular nanoparticle attachment and minimizing intracellular uptake provides a platform technology for LC‐DDS development.
Macrophages with doxorubicin‐loaded polymeric nanoparticles attached on cell surface (DOX‐NP@Mφ) through metal‐phenolic networks (MPNs) are constructed. DOX‐NP@Mφ can actively navigate to the tumor site, where photothermal effect from MPNs liberates DOX‐NP for improved tumor cell uptake and chemotherapy.
Different hypotheses have been proposed for the origin and pre-Cenozoic evolution of the Tibetan Plateau as a result of several collision events between a series of Gondwana-derived terranes (e.g., ...Qiangtang, Lhasa and India) and Asian continent since the early Paleozoic. This paper reviews and reevaluates these hypotheses in light of new data from Tibet including (1) the distribution of major tectonic boundaries and suture zones, (2) basement rocks and their sedimentary covers, (3) magmatic suites, and (4) detrital zircon constraints from Paleozoic metasedimentary rocks. The Western Qiangtang, Amdo, and Tethyan Himalaya terranes have the Indian Gondwana origin, whereas the Lhasa Terrane shows an Australian Gondwana affinity. The Cambrian magmatic record in the Lhasa Terrane resulted from the subduction of the proto-Tethyan Ocean lithosphere beneath the Australian Gondwana. The newly identified late Devonian granitoids in the southern margin of the Lhasa Terrane may represent an extensional magmatic event associated with its rifting, which ultimately resulted in the opening of the Songdo Tethyan Ocean. The Lhasa−northern Australia collision at ~263Ma was likely responsible for the initiation of a southward-dipping subduction of the Bangong-Nujiang Tethyan Oceanic lithosphere. The Yarlung-Zangbo Tethyan Ocean opened as a back-arc basin in the late Triassic, leading to the separation of the Lhasa Terrane from northern Australia. The subsequent northward subduction of the Yarlung-Zangbo Tethyan Ocean lithosphere beneath the Lhasa Terrane may have been triggered by the Qiangtang–Lhasa collision in the earliest Cretaceous. The mafic dike swarms (ca. 284Ma) in the Western Qiangtang originated from the Panjal plume activity that resulted in continental rifting and its separation from the northern Indian continent. The subsequent collision of the Western Qiangtang with the Eastern Qiangtang in the middle Triassic was followed by slab breakoff that led to the exhumation of the Qiangtang metamorphic rocks. This collision may have caused the northward subduction initiation of the Bangong-Nujiang Ocean lithosphere beneath the Western Qiangtang. Collision-related coeval igneous rocks occurring on both sides of the suture zone and the within-plate basalt affinity of associated mafic lithologies suggest slab breakoff-induced magmatism in a continent−continent collision zone. This zone may be the site of net continental crust growth, as exemplified by the Tibetan Plateau.
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► Reevaluating the origin and evolution of the Tibetan Plateau. ► Presenting a synthetic model for the pre-Cenozoic evolution of the Tibetan Plateau. ► Interpreting the coeval magmatism occurring on both sides of a suture in a collision zone as a result of slab breakoff.
The significance of the continental crust (CC) on which we live is self-evident. However, our knowledge remains limited on its origin, its way and rate of growth, and how it has acquired the ...“andesitic” composition from mantle derived magmas. Compared to rocks formed from mantle derived magmas in all geological environments, volcanic arc rocks associated with seafloor subduction share some common features with the CC; both are relatively depleted in “fluid-insoluble” elements (e.g., Nb, Ta and Ti), but enriched in “fluid-soluble” elements (e.g., U, K and Pb). These chemical characteristics are referred to as the “arc-like signature”, and point to a possible link between subduction-zone magmatism and CC formation, thus leading to the “island arc” model widely accepted for the origin of the CC over the past 45years. However, this “island–arc” model has many difficulties: e.g., (1) the bulk arc crust (AC) is basaltic whereas the bulk CC is andesitic; (2) the AC has variably large Sr excess whereas the CC is weakly Sr deficient; and (3) AC production is mass-balanced by subduction erosion and sediment recycling, thus contributing no net mass to the CC growth, at least in the Phanerozoic. Our recent and ongoing studies on granitoid rocks (both volcanic and intrusive) formed in response to the India–Asia continental collision (~55±10Ma) show remarkable compositional similarity to the bulk CC with the typical “arc-like signature”. Also, these syncollisional granitoid rocks exhibit strong mantle isotopic signatures, meaning that they were recently derived from a mantle source. The petrology and geochemistry of these syncollisional granitoid rocks are most consistent with an origin via partial melting of the upper ocean crust (i.e., last fragments of underthrusting ocean crust upon collision) under amphibolite facies conditions, adding net mantle-derived materials to form juvenile CC mass. This leads to the logical and testable hypothesis that continental collision produces and preserves the juvenile crust, and hence maintains net CC growth.
Importantly, the history of the Greater Tibetan Plateau from the Early Paleozoic to present manifests the history of “super” continent amalgamation through a series of continental collision events with production and preservation of abundant syncollisional granitoids. Plate tectonics in terms of seafloor spreading and subduction is a continuous process on a global scale since its inception (in the early Archean?), whereas continental collision on regional scales and super-continental formation on a global scale are episodic (vs. continuous). Hence, continental collision with juvenile crust formation/preservation and super-continent amalgamation explains the episodic growth of the CC. We are continuing testing and refining this hypothesis by detailed petrological, geochemical and geochronological studies of syncollisional granitoids along older collision zones in central-west China, especially on the northern Tibetan Plateau in a global context.
Identifying arc‐trench systems along with spatial and temporal variations in their record of tectono‐magmatic events is crucial for determining the orogenic divers and evolution of orogenic systems. ...New geochronological and geochemical data of Jurassic igneous rocks, as well as detrital zircon data from contemporaneous sedimentary units, within the eastern Bangong‐Nujiang suture in central Tibet indicate the existence of an approximately 1,200‐km Middle‐Late Jurassic magmatic arc system. This arc system can be divided into two distinct along‐strike segments, which are characterized by magmatic activity extending from 166 to 160 Ma in the east and 170–148 Ma in the west, followed by magmatic gaps at 160–120 and 148–125 Ma, respectively. An accretionary prism, magmatic arc, and retro‐arc sedimentary units are identified from south to north in the eastern segment. The 166–160 Ma arc includes high‐K calc‐alkaline granitoids, and high‐Mg andesites, dacites, and rhyolites, which collectively can be interpreted to originate from partial melting of ancient lower crust and mélange diapirs above a north dipping subduction zone. Our analysis reveals the existence of an overall compressional arc‐trench system along strike, which overlaps with a phase of 170–160 Ma ophiolite generation and a rock association of 160–148 Ma slab‐derived adakites and oceanic island basalt‐type rocks, and is followed by an overall magmatic gap during 148–125 Ma with subsequent 125–105 Ma extensive magmatism. We infer that these records may reflect sequential tectonic events, including subparallel ridge‐trench collision (170–160 Ma), slab window formation (160–148 Ma), subsequent subduction termination (148–125 Ma), and final Lhasa‐Qiangtang amalgamation (125–105 Ma).
Key Points
An ~1,200‐km‐long Middle‐Late Jurassic magmatic arc flanked by coeval sedimentary units
An overall compressional convergent margin overlapping with ophiolite generation and slab window magmatism, and followed by a magmatic gap
Sequential events including subparallel ridge‐trench collision, slab window formation, subduction termination, and Lhasa‐Qiangtang amalgamation
The photocatalytic reduction of N₂ to NH₃ is typically hampered by poor binding of N₂ to catalytic materials and by the very high energy of the intermediates involved in this reaction. Solvated ...electrons directly introduced into the reactant solution can provide an alternative pathway to overcome such limitations. Here we demonstrate that illuminated hydrogen-terminated diamond yields facile electron emission into water, thus inducing reduction of N₂ to NH₃ at ambient temperature and pressure. Transient absorption measurements at 632 nm reveal the presence of solvated electrons adjacent to the diamond after photoexcitation. Experiments using inexpensive synthetic diamond samples and diamond powder show that photocatalytic activity is strongly dependent on the surface termination and correlates with the production of solvated electrons. The use of diamond to eject electrons into a reactant liquid represents a new paradigm for photocatalytic reduction, bringing electrons directly to reactants without requiring molecular adsorption to the surface.
The analytical solutions for the mode-I and mode-II stress intensity factor (SIF) of arbitrary distributed offset parallel cracks in brittle solids were generated based on the Kachanov method and ...superposition principle. By analyzing the SIF ratio, effects of the horizontal interval, vertical interval, crack inclination angle and crack length on the interaction of offset parallel cracks were estimated, and the interference area of the crack was determined theoretically. Numerical models were established using the finite element method (FEM) to show the performance of the present method, and the relationship between crack propagation and crack interaction was discussed. The results show that the SIFs obtained from the present method agree well with the accurate ones. The interaction of offset parallel cracks contains three types, i.e. reinforcing effect, shielding effect and null-effect, which can convert mutually with the change in interval, crack inclination angle and crack length. The interference area of the crack can be divided into reinforcing, shielding area and null-effect area which are symmetric about the crack. The reinforcing effect facilitates crack propagation while the shielding effect inhibits crack propagation.
•The analytical solutions to the mode-I and II stress intensity factor of offset parallel cracks were generated.•Effects of the geometric parameters of offset parallel cracks on the interaction were estimated.•The interference area of the crack was determined theoretically.
Vehicular ad hoc network(VANET) is a special mobile ad hoc network (MANET) which plays an important role in the intelligent traffic system(ITS). Based on the high mobility of VANETs, the security ...problems have not been reasonably solved when we enjoy the convenience brought by the Location Based Service(LBS). We present a blockchain-based trust management model for location privacy preserving. The scheme allows vehicles to use certificate to request LBS without revealing their privacy information. We construct anonymous cloaking region to ensure the privacy security of vehicles. We propose a trust management algorithm to constrain and standardize the behavior of vehicles, and use blockchain to implement the data security of vehicles. In the experiments, we conduct the tests with various data sets. Security analysis and experiments show that the system is resilient to sorts of trust model attacks, which can better preserve the privacy security of vehicles. Simulation results reveal that the proposed system is effective and feasible in collect.
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