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Earth’s mantle has a two-layered structure, with the upper and lower mantle domains separated by a seismic discontinuity at about 660 km (refs. 1,2). The extent of mass transfer between these mantle domains throughout Earth’s history is, however, poorly understood. Continental crust extraction results in Ti-stable isotopic fractionation, producing isotopically light melting residues3–7. Mantle recycling of these components can impart Ti isotope variability that is trackable in deep time. We report ultrahigh-precision 49Ti/47Ti ratios for chondrites, ancient terrestrial mantle-derived lavas ranging from 3.8 to 2.0 billion years ago (Ga) and modern ocean island basalts (OIBs). Our new Ti bulk silicate Earth (BSE) estimate based on chondrites is 0.052 ± 0.006‰ heavier than the modern upper mantle sampled by normal mid-ocean ridge basalts (N-MORBs). The 49Ti/47Ti ratio of Earth’s upper mantle was chondritic before 3.5 Ga and evolved to a N-MORB-like composition between approximately 3.5 and 2.7 Ga, establishing that more continental crust was extracted during this epoch. The +0.052 ± 0.006‰ offset between BSE and N-MORBs requires that <30% of Earth’s mantle equilibrated with recycled crustal material, implying limited mass exchange between the upper and lower mantle and, therefore, preservation of a primordial lower-mantle reservoir for most of Earth’s geologic history. Modern OIBs record variable 49Ti/47Ti ratios ranging from chondritic to N-MORBs compositions, indicating continuing disruption of Earth’s primordial mantle. Thus, modern-style plate tectonics with high mass transfer between the upper and lower mantle only represents a recent feature of Earth’s history.

Silicon and oxygen are potential light elements in Earth's core because their stronger affinity to metal observed with increasing temperature posits that significant amounts of both can be incorporated into the core. It was proposed that an Fe–Si–O liquid alloy could expel SiO2at the core‐mantle boundary during secular cooling, leaving the core with either silicon or oxygen, not both. This was recently challenged in a study showing no exsolution but immiscibility in the Fe–Si–O system. Here we investigate the liquidus field of Fe–Si and Fe–O binaries and Fe–Si–O ternaries at core‐mantle boundary pressures and temperatures using ab initio molecular dynamics. We find that the liquids remain well mixed with ternary properties identical to mixing of binary properties. Two‐phase simulations of solid SiO2and liquid Fe show dissolution at temperatures above 4100 K, suggesting that SiO2crystallization as well as liquid immiscibility in Fe–Si–O is unlikely to occur in Earth's core. The standard hypothesis is that Earth's core inherited its composition (iron‐nickel alloy + lighter elements such as Si, O, S, and C) during core formation by interaction with Earth's silicate magma ocean and has since remained fixed and well mixed through geological time. It was recently proposed, on the basis of high‐pressure experiments, that silicon and oxygen dissolved in the core could crystallize as SiO2at the core‐mantle boundary during secular cooling, challenging our understanding of core composition and evolution. While other experimental studies have not corroborated these findings, a recent study involving experiments and calculations proposed no SiO2exsolution but rather liquid‐liquid immiscibility in the iron‐silicon‐oxygen system. In this study, we use ab initio molecular dynamics simulations to theoretically investigate the liquidus field of Fe–Si, Fe–O and Fe–Si–O alloys. We find that (1) the liquid alloys remain stable and well mixed, with the volumes of iron, silicon, and oxygen mixing ideally at core conditions; (2) no sign of SiO2crystallization or phase separation (i.e., immiscibility); and (3) simulations of solid SiO2in contact with liquid Fe show mixing of both phases, ruling out silica precipitation out of the core. Liquid Fe‐Si‐O alloys are well mixed at core‐mantle boundary conditions; properties are identical to ideal volume mixing of binariesTwo‐phase ab initio molecular dynamics simulations show that solid SiO2and liquid Fe mix at and above 4100 K at 136 GPaSiO2crystallization from an Fe‐Si‐O alloy is unlikely for a range of plausible temperatures at the core‐mantle boundary

Earth’s core is essentially composed of a light-element bearing iron-nickel alloy (Birch 1964). The nickel content in the core has negligible effects on physical properties such as density and compressibility (e.g., Lin et al. 2003; Kantor et al. 2007; Martorell et al. 2013; Badro et al. 2014). This deters any attempt to determine or even estimate the nickel content of the core using seismological models, as in the case of light elements. It was recently proposed that the presence of nickel should fractionate iron isotopes in small planetary cores (Elardo and Shahar 2017), but the effect for a large (hot) planet such as the Earth would not be measurable; this observation, however, opens up the possibility that Ni can have an effect on element partitioning between the metallic alloy and the silicate melt during core formation. In this case, the siderophile trace-element composition of the mantle would, in turn, constrain the Fe/Ni ratio in the core. Here, we investigated the effect of nickel concentration in the metallic alloy on the partitioning of other elements at conditions directly relevant to core formation, using the laser-heated diamond-anvil cell. We found no measurable effect of nickel concentration on the partitioning of Ni, Cr, and V; the Fe-Ni alloy is chemically ideal over a broad range of Ni concentrations (3.5 to 48.7 wt%). The ideality of the Fe-Ni solution across a wide range of nickel concentration shows that Fe and Ni are not only twins from the standpoint for material properties, but also from that of chemical properties in those high P-Tconditions.

Electrorheological (ER) technology is an advanced technology based on ER effects. The most common material in ER technology is an electrorheological fluid (ERF), which is a type of smart soft material. The viscosity of ERF is reversibly adjustable by an applied electric field. A new type of electroresponsive soft material, electrorheological elastomer (ERE), which is a derivative of ERFs, has attracted wide attention due to its advantages of not precipitating and easy packaging. ER materials are widely applied in mechanical engineering due to their reversibly tunable characteristics, fast response, and low energy consumption. In addition to basic ER material fabrication and application, ER technology is also used in energy material preparation, oil transportation, and energy storage. The application of ER technology in the energy field provides a good example of the potential applications of ER technology in other fields. This article systematically summarizes the research status and future development prospects of ER technology in materials, energy, and mechanical engineering from the mechanism to application, combined with the latest research results.

This study aimed to determine whether PGI2would be evoked by the endogenous endothelial B2receptor agonist bradykinin (BK) in the porcine interlobular renal artery and, if so, to determine how it would influence the vasomotor reaction, and the specific cyclooxygenase (COX) isoform(s) involved in its synthesis. The production of the PGI2metabolite 6-keto-PGF1αwas analyzed with HPLC-mass spectroscopy, while vasomotor reaction to PGI2or BK was determined with isometric force measurement. Results showed that BK evoked an increase in the production of 6-keto-PGF1α, which was abolished by endothelial denudation that removed COX-1 expression, or was reduced by COX-1 inhibition. Interestingly, PGI2evoked a potent contraction, which was prevented by antagonizing thromboxane-prostanoid (TP) receptors and was not enhanced by antagonizing the vasodilator PGI2(IP) receptors. The IP receptor agonists MRE-269 and iloprost did not induce any relaxation. Moreover, iloprost, which is also a PGI2analog, caused a contraction, which was sensitive to TP receptor antagonism, but was to a significantly lesser extent than that of PGI2. Indeed, IP receptors were not detected by RT-PCR or Western blotting in the vessel. Following nitric oxide synthase (NOS) inhibition, BK also evoked an endothelium-dependent contraction, which was blocked by TP receptor antagonism. In addition, inhibition of COX-1 (but not COX-2) impeded the vasoconstrictor activity of BK and expedited the relaxation induced by the agonist in NOS-intact vessels. These results demonstrate that in the porcine interlobular renal artery BK evokes endothelial COX-1-mediated PGI2synthesis, which mainly leads to the activation of TP receptors and a vasoconstrictor response, possibly due to a scarcity of vasodilator activity mediated by IP receptors. Also, our data suggested that the effect of a PGI2analog on TP receptors could be reduced compared with that of PGI2due to modified structure as with iloprost.

Depression symptoms are often found in patients suffering from chronic pain, a phenomenon that is yet to be understood mechanistically. Here, we systematically investigate the cellular mechanisms and circuits underlying the chronic-pain-induced depression behavior. We show that the development of chronic pain is accompanied by depressive-like behaviors in a mouse model of trigeminal neuralgia. In parallel, we observe increased activity of the dopaminergic (DA) neuron in the midbrain ventral tegmental area (VTA), and inhibition of this elevated VTA DA neuron activity reverses the behavioral manifestations of depression. Further studies establish a pathway of glutamatergic projections from the spinal trigeminal subnucleus caudalis (Sp5C) to the lateral parabrachial nucleus (LPBN) and then to the VTA. These glutamatergic projections form a direct circuit that controls the development of the depression-like behavior under the state of the chronic neuropathic pain.

ABSTRACTNon-alcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid accumulation unrelated to excess alcohol intake, in which the hepatic expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is inhibited. Long non-coding RNA HOTAIR suppresses PTEN expression in hepatic stellate cells during liver fibrosis, and it is involved in liver lipid dysregulation. In this study, we evaluated whether the PTEN down-regulation and lipid accumulation in hepatic cells might be mediated by HOTAIR during the development of NAFLD. Free fatty acids (FFAs) treatment promoted triglyceride accumulation in HepG2 cells, significantly increasing HOTAIR expression and inhibiting PTEN expression (both at mRNA and protein levels).The effects on HOTAIR and PTEN expressions disappeared after withdrawal of the FFAs treatment. SiRNA-mediated HOTAIR knockdown prevented PTEN down-regulation and triglyceride accumulation in HepG2 cells treated with FFAs; and CAPE (an NF-κBp65 inhibitor) treatment prevented the HOTAIR up-regulation and PTEN down-regulation. FFAs could induce the up-regulation of HOTAIR in HepG2 cells probably dependent on the NF-κB signaling, and consequently suppress PTEN expression and promote triglyceride accumulation. Aberrant up-regulation of HOTAIR mediated by excessive circulating FFAs levels may be a crucial mechanism associated with liver steatosis.