Two crustal cross sections through the eastern margin of the Tibetan Plateau are jointly determined from deep seismic sounding. The E–W trending line AA’ passes through the western Sichuan plateau ...(including the Songpan‐Garze terrane and the Longmenshan fault belt) and ends in the Sichuan basin (a part of the Yangtze craton). Line BB’ has a trend of NNE and crosses the Songpan‐Garze terrane. Two‐dimensional crustal structures along the profiles were jointly determined by the additional use of existing deep seismic sounding data. Our seismic velocity models indicate that the western Sichuan plateau and the Sichuan basin have crustal thicknesses of 62 and 43 km, average crustal P wave velocities of 6.27 and 6.45 km/s and lower crustal (Vp > 6.5 km/s) thicknesses of 27 and 15 km, respectively. Density models constructed from the seismic velocity models are consistent with observed Bouguer gravity anomalies. We infer that collision between the Tibetan Plateau and the Yangtze craton has caused thickening of the lower crust and uplift of the western Sichuan plateau. We detect a low‐velocity layer in the upper crust of the western Sichuan plateau but observe no equivalence in the Sichuan basin; west dipping thrusts may detach into this low‐velocity layer. The seismic phase PmP in the western Sichuan plateau has low amplitude, suggesting high attenuation in the lower crust (Qp of 100–300). We suggest that the high attenuation is a consequence of lower crustal flow caused by the large lower crustal thickness beneath the western Sichuan plateau.
Microalgae have been emerging as an important source for the production of bioactive compounds. Marine diatoms can store high amounts of lipid and grow quite quickly. However, the genetic and ...biochemical characteristics of fatty acid biosynthesis in diatoms remain unclear. Glycerophospholipids are integral as structural and functional components of cellular membranes, as well as precursors of various lipid mediators. In addition, diacylglycerol acyltransferase (DGAT) is a key enzyme that catalyzes the last step of triacylglyceride (TAG) biosynthesis. However, a comprehensive sequence-structure and functional analysis of DGAT in diatoms is lacking. In this study, an isoform of diacylglycerol acyltransferase type 2 of the marine diatom Phaeodactylum tricornutum was characterized. Surprisingly, DGAT2 overexpression in P. tricornutum stimulated more oil bodies, and the neutral lipid content increased by 35%. The fatty acid composition showed a significant increase in the proportion of polyunsaturated fatty acids; in particular, EPA was increased by 76.2%. Moreover, the growth rate of transgenic microalgae remained similar, thereby maintaining a high biomass. Our results suggest that increased DGAT2 expression could alter fatty acid profile in the diatom, and the results thus represent a valuable strategy for polyunsaturated fatty acid production by genetic manipulation.
Over the past decade, supramolecular compounds with organometallic Ir, Rh, Ru based half-sandwich complexes have received considerable attention as materials with a variety of potential applications. ...The major emphasis of this tutorial review lies on the self-assembly of such organometallic half-sandwich molecular rectangles, prisms and cages with half-sandwich corners and two different rigid bifunctional ligands using an approach of stepwise construction. Synthetic methods and the structural and functional properties of the target complexes are discussed in detail.
Optoelectronic synapses integrating synaptic and optical-sensing functions exhibit large advantages in neuromorphic computing for visual information processing and complex learning, recognition, and ...memory in an energy-efficient way. However, electric stimulation is still essential for existing optoelectronic synapses to realize bidirectional weight-updating, restricting the processing speed, bandwidth, and integration density of the devices. Herein, a two-terminal optical synapse based on a wafer-scale pyrenyl graphdiyne/graphene/PbS quantum dot heterostructure is proposed that can emulate both the excitatory and inhibitory synaptic behaviors in an optical pathway. The simple device architecture and low-dimensional features of the heterostructure endow the optical synapse with robust flexibility for wearable electronics. This optical synapse features a linear and symmetric conductance-update trajectory with numerous conductance states and low noise, which facilitates the demonstration of accurate and effective pattern recognition with a strong fault-tolerant capability even at bending states. A series of logic functions and associative learning capabilities have been demonstrated by the optical synapses in optical pathways, significantly enhancing the information processing capability for neuromorphic computing. Moreover, an integrated visible information sensing memory processing system based on the optical synapse array is constructed to perform real-time detection, in situ image memorization, and distinction tasks. This work is an important step toward the development of optogenetics-inspired neuromorphic computing and adaptive parallel processing networks for wearable electronics.
Graphdiyne (GDY) is emerging as a promising material for various applications owing to its unique structure and fascinating properties. However, the application of GDY in electronics and ...optoelectronics are still in its infancy, primarily owing to the huge challenge in the synthesis of large-area and uniform GDY film for scalable applications. Here a modified van der Waals epitaxy strategy is proposed to synthesize wafer-scale GDY film with high uniformity and controllable thickness directly on graphene (Gr) surface, providing an ideal platform to construct large-scale GDY/Gr-based optoelectronic synapse array. Essential synaptic behaviors have been realized, and the linear and symmetric conductance-update characteristics facilitate the implementation of neuromorphic computing for image recognition with high accuracy and strong fault tolerance. Logic functions including “NAND” and “NOR” are integrated into the synapse which can be executed in an optical pathway. Moreover, a visible information sensing-memory-processing system is constructed to execute real-time image acquisition,
in situ
image memorization and distinction tasks, avoiding the time latency and energy consumption caused by data conversion and transmission in conventional visual systems. These results highlight the potential of GDY in applications of neuromorphic computing and artificial visual systems.
The unavoidable interaction of an open quantum system with its surrounding environment may follow non-Markovian dynamics behavior, which causes its memory effects to play a key role in many quantum ...technologies. In this work, we first consider the dynamics control of a spin-1/2 system that simultaneously interacts with two magnets. Subsequently, we study in detail the evolution of a classically driven spin-1/2 system that is coupled with a magnet. Two dynamical crossovers of the spin system, namely, from Markovian dynamics to non-Markovian dynamics and from no-speedup evolution to speedup evolution, can be controlled in these two models. Slightly different from the previous quantum speedup scenarios with controllable non-Markovianity, the stronger non-Markovianity does not necessarily lead to the quantum speedup dynamics process of the spin system in our spin-magnet schemes.
•A novel theoretical solution is proposed to predict the critical load of out-of-plane buckling of perforated arches under a central concentrated load.•Experimental results of out-of-plane buckling ...of perforated arches are presented.•FE models are validated using experimental results.•The accuracy of the proposed analytical model is checked using FEA results.
Perforated arches with cellular openings are widely used as roof beams in various buildings due to the functional and appearance requirements of architecture. Perforated arches under a central concentrated load may suffer from out-of-plane buckling when the load reaches to a critical value. This paper presents the analytical solution based on the energy method to predict the critical load of perforated arches under a central concentrated load. Experimental tests and finite element analyses are also carried out for perforated circular aluminum arch specimens to validate the present analytical solution. Good agreement between the analytical, experimental, and numerical results is demonstrated. The present results show that the size of web openings and the slenderness of the arch could affect the out-of-plane buckling behavior of perforated arches significantly. The arch with larger web perforations or larger slenderness ratio has the lower critical load of out-of-plane buckling.
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•An electrochemical system for salinity gradient energy harvesting is designed.•The system uses pseudocapacitive Mn3(PO4)2 for efficiency energy harvesting.•The energy density ...produced of the device is about 5.31 J g−1 or 42.48 mJ cm−2.
Salinity gradient energy, which is abundant along the coastline in ocean, is a kind of chemical energy existing the solutions of different concentrations mixing. The pressure retarded osmosis, reverse electrodialysis and accumulator mixing technology are currently the most common approaches to harvest salinity gradient energy. Here we report an electrochemical device using active carbon as anode and manganese phosphate as cathode for salinity gradient energy harvesting, which shows an energy density of 5.31 J g−1, indicating a potential application in the field of ocean energy utilization.
We quantified the size-dependent energy bandgap modulation of ZnO nanowires under tensile strain by an in situ measurement system combining a uniaxial tensile setup with a cathodoluminescence ...spectroscope. The maximal strain and corresponding bandgap variation increased by decreasing the size of the nanowires. The adjustable bandgap for the 100 nm nanowire caused by a strain of 7.3% reached approximately 110 meV, which is nearly double the value of 59 meV for the 760 nm nanowire with a strain of 1.7%. A two-step linear feature involving bandgap reduction caused by straining and a corresponding critical strain was identified in ZnO nanowires with diameters less than 300 nm. The critical strain moved toward the high strain level with shrunken nanowires. The distinct size effect of strained nanowires on the bandgap variation reveals a competition between core-dominated and surface-dominated bandgap modulations. These results could facilitate potential applications involving nanowire-based optoelectronic devices and band-strain engineering.
The main problem of salinity gradient energy extraction using activated carbon (AC) as electrode is charge leakage. We used the chemical charging method to chemically modify the activated carbon ...electrode so that its surface carries different charged groups. Activated carbon electrodes with different charged properties show strong concentration response. We treated the activated carbon with nitric acid, then chemically modified it with 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide (EDC) and 1-aminopropyl-3-methylimidazolium bromide (APMIB) to obtain a positively charged AC-P electrode material with brominium groups on the surface; The activated carbon treated with nitric acid was mixed with a hydrophilic charged polymer binder modified with carboxy methyl cellulose (CMC) by sulfosuccic acid (SSA), and an AC-S electrode material with negative surface sulfonic groups was obtained. These two methods are used to regulate the charge properties on the surface of activated carbon, improve the hydrophilicity and ion selectivity of activated carbon electrode, and the electrode materials show different concentration response effects. By assembling activated carbon materials AC-P and AC-S carrying positive and negative charged groups respectively into capacitors AC-P//AC-S, salinity gradient energy extraction is carried out by four-step cycle method without charging and 2.69 J m−2 energy is obtained. The extraction of salinity gradient energy from common activated carbon was realized after chemical modification.
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