We process rigorously GPS data observed during the past 25 years from continental China to derive site secular velocities. Analysis of the velocity solution leads to the following results. (a) The ...deformation field inside the Tibetan plateau and Tien Shan is predominantly continuous, and large deformation gradients only exist perpendicular to the Indo‐Eurasian relative plate motion and are associated with a few large strike‐slip faults. (b) Lateral extrusions occur on both the east and west sides of the plateau. The westward extrusion peaks at ~6 mm/yr in the Pamir‐Hindu Kush region. A bell‐shaped eastward extrusion involves most of the plateau at a maximum rate of ~20 mm/yr between the Jiali and Ganzi‐Yushu faults, and the pattern is consistent with gravitational flow in southern and southeastern Tibet where the crust shows widespread dilatation at 10–20 nanostrain/yr. (c) The southeast borderland of Tibet rotates clockwise around the eastern Himalaya syntaxis, with sinistral and dextral shear motions along faults at the outer and inner flanks of the rotation terrane. The result suggests gravitational flow accomplished through rotation and translation of smaller subblocks in the upper crust. (d) Outside of the Tibetan plateau and Tien Shan, deformation field is block‐like. However, unnegligible internal deformation on the order of a couple of nanostrain/yr is found for all blocks. The North China block, under a unique tectonic loading environment, deforms and rotates at rates significantly higher than its northern and southern neighboring blocks, attesting its higher seismicity rate and earthquake hazard potential than its neighbors.
Key Points
Production of a GPS velocity solution in China with rigorous processing and accounting for effects of large earthquakes
Comprehensive analysis of distributed deformation within Tibetan plateau and Tien Shan and block‐like deformation for the rest of region
Quantification of two‐way extrusion of Tibetan plateau and clockwise rotation of its southeast borderland
We derive a detailed horizontal velocity field for the southeast borderland of the Tibetan Plateau using GPS data collected from the Crustal Motion Observation Network of China between 1998 and 2004. ...Our results reveal a complex deformation field that indicates that the crust is fragmented into tectonic blocks of various sizes, separated by strike‐slip and transtensional faults. Most notably, the regional deformation includes 10–11 mm/yr left slip across the Xianshuihe fault, ∼7 mm/yr left slip across the Anninghe‐Zemuhe‐Xiaojiang fault zone, ∼2 mm/yr right slip across a shear zone trending northwest near the southern segment of the Lancang River fault, and ∼3 mm/yr left slip across the Lijiang fault. Deformation along the southern segment of the Red River fault appears not significant at present time. The region south and west of the Xianshuihe‐Xiaojiang fault system, whose eastward motion is resisted by the stable south China block to the east, turns from eastward to southward motion with respect to south China, resulting in clockwise rotation of its internal subblocks. Active deformation is detected across two previously unknown deformation zones: one is located ∼150 km northwest of and in parallel with the Longmenshan fault with 4–6 mm/yr right‐slip and another is continued south‐southwestward from the Xiaojiang fault abutting the Red River fault with ∼7 mm/yr left slip. While both of these zones are seismically active, the exact locations of faults responsible for such deformation are yet to be mapped by field geology. Comparing our GPS results with predictions of various models proposed for Tibetan Plateau deformation, we find that the relatively small sizes of the inferred microblocks and their rotation pattern lend support to a model with a mechanically weak lower crust experiencing distributed deformation underlying a stronger, highly fragmented upper crust.
A porous MoO2 nanosheet as an active and stable bifunctional electrocatalyst for overall water splitting, is presented. It needs a cell voltage of only about 1.53 V to achieve a current density of 10 ...mA cm−2 and maintains its activity for at least 24 h in a two‐electrode configuration.
Developing non‐noble metal catalysts as Pt substitutes, with good activity and stability, remains a great challenge for cost‐effective electrochemical evolution of hydrogen. Herein, ...carbon‐encapsulated WOx anchored on a carbon support (WOx@C/C) that has remarkable Pt‐like catalytic behavior for the hydrogen evolution reaction (HER) is reported. Theoretical calculations reveal that carbon encapsulation improves the conductivity, acting as an electron acceptor/donor, and also modifies the Gibbs free energy of H* values for different adsorption sites (carbon atoms over the W atom, O atom, WO bond, and hollow sites). Experimental results confirm that WOx@C/C obtained at 900 °C with 40 wt% metal loading has excellent HER activity regarding its Tafel slope and overpotential at 10 and 60 mA cm−2, and also has outstanding stability at −50 mV for 18 h. Overall, the results and facile synthesis method offer an exciting avenue for the design of cost‐effective catalysts for scalable hydrogen generation.
Experimental and theoretical studies on carbon‐encapsulated WO
x anchored onto carbon supports, as a remarkable Pt‐like catalyst for the hydrogen evolution reaction are presented. Theoretical calculations reveal that the encapsulated carbon atoms play the key role in improving the conductivity of the materials and modifying the Gibbs free energy of H* values for different adsorption sites.
Using the measurements of ∼726 GPS stations around the Tibetan Plateau, we determine the rigid rotation of the entire plateau in a Eurasia‐fixed reference frame which can be best described by an ...Euler vector of (24.38° ± 0.42°N, 102.37° ± 0.42°E, 0.7096° ± 0.0206°/Ma). The rigid rotational component accommodates at least 50% of the northeastward thrust from India and dominates the eastward extrusion of the northern plateau. After removing the rigid rotation to highlight the interior deformation within the plateau, we find that the most remarkable interior deformation of the plateau is a “glacier‐like flow” zone which starts at somewhere between the middle and western plateau, goes clockwise around the Eastern Himalayan Syntaxis (EHS), and ends at the southeast corner of the plateau with a fan‐like front. The deformation feature of the southern plateau, especially the emergence of the flow zone could be attributed to an eastward escape of highly plastic upper crustal material driven by a lower crust viscous channel flow generated by lateral compression and gravitational buoyancy at the later developmental stage of the plateau. The first‐order feature of crustal deformation of the northeastern plateau can be well explained by a three‐dimensional elastic half‐space dislocation model with rates of dislocation segments comparable to the ones from geological observations. In the eastern plateau, although GPS data show no significant convergence between the eastern margin of the plateau and the Sichuan Basin, a small but significant compressional strain rate component of ∼10.5 ± 2.8 nstrain/yr exists in a relatively narrow region around the eastern margin. In addition, a large part of the eastern plateau, northeast of the EHS, is not undergoing shortening along the northeastward convergence direction of the EHS but is stretching.
Engineering novel Sn‐based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy ...nanoparticles (x up to 0.20) with native Bi‐doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi‐SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state‐of‐the‐art Bi‐SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO.
The first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) is successfully achieved with native Bi‐atoms‐doped amorphous SnOx nanoshells for highly efficient CO2 reduction into formate, outperforming current tin oxide catalysts.
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•MoP-Mo2C quantum dot heterostructures uniformly distribute on carbon sheet network.•MoP-Mo2C/NPC possesses abundant heterogeneous interfaces and pore structure.•MoP-Mo2C/NPC exhibits ...low overpotentials and ultrahigh stability for HER and OER.
In this work, we constructed MoP-Mo2C quantum dot heterostructures uniformly hosted on a three-dimensional (3D) hierarchically porous thin N,P-doped carbon sheet network (MoP-Mo2C/NPC) by a novel one-pot simultaneous phosphating-carbonization-activation of molybdenum-chelated resin and KOH. Chelate confinement not only prevents the aggregation of MoP/Mo2C quantum dots, but also synchronously produces a carbon sheet network doped with N and P without the requirement for post-atom doping. The prepared MoP-Mo2C/NPC exhibited a large specific surface area, a high electron conductivity, and abundant active sites for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). As a result, MoP-Mo2C/NPC with a low calculated Gibbs free energy for H adsorption exhibited an excellent electrocatalytic activity and an ultrahigh stability for both the HER and OER processes in an alkaline medium. In addition, the assembled MoP-Mo2C/NPC || MoP-Mo2C/NPC alkaline electrolyzer delivered a current density of 10 mA cm−2 at an overpotential of only 1.55 V, and maintained > 95% of the initial current density after 168 h (1 week) of activity, which is superior to that of the state-of-the-art Pt/C || RuO2/C system in the overall water splitting process.
Despite the importance of viscoelasticity in the evolution of crustal stress/strain being widely recognized, the interpretation of interseismic geodetic measurements for assessing earthquake ...potential is still based overwhelmingly on elastic models. The reasons for this disparity include conflating deformation rates with deformation itself and the lack of a succinct representation of the seismic readiness of a locked fault in a viscoelastic Earth. Using a classical viscoelastic model for strike‐slip faults, we reiterate the commonly overlooked message that, if the recurrence interval is long, most of the strain energy for the next earthquake accrues early in the cycle, and low strain rates later in the cycle by no means indicate diminished rupture potential. Fault stress stays near failure for much of the late interseismic period which may explain why slow slip‐rate faults have more variable recurrence intervals than fast slip‐rate faults. We propose to use displacement deficit instead of slip deficit to represent seismic readiness.
Plain Language Summary
Modern satellite measurements can reveal how quickly faults are being loaded by tectonic plate motions, and seismic hazard models use these loading rates as proxy for the likelihood of a pending earthquake. However, because of the partially fluid‐like behavior of Earth's interior, these loading rates have actually evolved with time since the last rupture. For faults with long intervals between successive earthquakes, these rates slow down substantially as the next event draws near. We, therefore, caution that slow rates of loading should not be assumed to reflect limited earthquake potential.
Key Points
Because of viscoelasticity, faults with long recurrence intervals accrue most of their elastic strain early in the interseismic period
Strain rates should not be conflated with stored strain, and slow geodetic deformation rates do not imply limited earthquake potential
For strike‐slip faults, “Relative Displacement Deficit” is a better measure of the earthquake readiness of a fault than “slip deficit”
To get carbon electrode with both excellent gravimetric and volumetric capacitances at high mass loadings is critical to supercapacitors. Herein, cracked defective graphene nanospheres (GNS) well ...meet above requirements. The morphology and structure of the GNS are controlled by polystyrene sphere template/glucose ratio, microwave heating time, and Fe content. The typical GNS with specific surface area of 2794 m2 g−1, pore volume of 1.48 cm3 g−1, and packing density of 0.74 g cm−3 performs high gravimetric and volumetric capacitances of 529 F g−1 and 392 F cm−3 at 1A g−1 with a capacitance retention of 62.5% at 100 A g−1 in a three‐electrode system in 6 mol L−1 KOH aqueous electrolyte. In a two‐electrode system, the GNS possesses energy density of 18.6 Wh kg−1 (13.8 Wh L−1) at the power density of 504 W kg−1, which is higher than all reported pure carbon materials in gravimetric energy density and higher than all reported heteroatom‐doped carbon materials in volumetric energy density, in aqueous solution, as far as it is known. A structural feature of carbon materials that possess both high energy density and high power density is pointed out here.
Graphene nanospheres (GNSs) are prepared through dispersing, cracking, and graphitization of glucose. The GNSs have ultrahigh specific surface area, dense defects, high packing density, and excellent ion and electron transfer performances. The GNSs show higher gravimetric energy density than the best pure carbon electrodes and higher volumetric energy density even than the best heteroatom‐doped carbon electrodes.
Precise connectivity in neuronal circuits is a prerequisite for proper brain function. The dauntingly complex environment encountered by axons and dendrites, even after navigation to their target ...area, prompts the question of how specificity of synaptic connections arises during development. We review developmental strategies and molecular mechanisms that are used by neurons to ensure their precise matching of pre- and postsynaptic elements. The emerging theme is that each circuit uses a combination of simple mechanisms to achieve its refined, often complex connectivity pattern. At increasing levels of resolution, from lamina choice to subcellular targeting, similar signaling concepts are reemployed to narrow the choice of potential matches. Temporal control over synapse development and synapse elimination further ensures the specificity of connections in the nervous system.
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