SUMMARY
The crustal structure is a window to understand the tectonic evolution of an area. Through the first large-scale passive-source ocean bottom seismometer (OBS) array observation experiment in ...the Eastern Subbasin of the South China Sea (ESSCS), we calculated and obtained the respective receiver functions of these stations. As OBS works on the seafloor, where the working environment is different from that for its land-based counterpart, the effects of the sea-water layer and the oceanic low-velocity sediment layer on the seismic signals must be evaluated. Receiver functions’ synthetic test demonstrates the following: the presence of the sea-water layer produces a strong negative-amplitude phase (Pwp) in the receiver function, and the arrival time of this phase is delayed as the thickness of the sea-water layer increases; the presence of the low-velocity sediment layer produces a strong positive-amplitude phase (Pseds) which causes a delay in the arrival time of the Moho-related phases of the receiver function and makes them difficult to distinguish. On the basis of phase identification and synthetic tests, we estimate crustal thickness beneath each of the stations using two approaches. The first approach utilizes the observed arrival time of Moho phases, and the second approach finds the optimal crustal thickness by comparing the synthetic and observed receiver functions, which leads to more reliable results. The results of the second method show that the thickness of the sediment in the study area is mainly controlled by seafloor topography, the thickness of the crust in the seamount area is affected by the magma supply during the expansion stage and the post-spreading magmatism, and the crust in the flat basin is only affected by the magma supply during the expansion period. Moreover, the crust in the area affected by magmatic activity after the expansion stage is thicker than that in the area not affected.
The self-assembly of hydrophobically modified polymers has become a research hotspot due to its wide application in the biomedical field. Recombinant human epidermal growth factors (rhEGFs) are ...molecules that are able to enhance wound healing; however, they have a short half-life and require sustained action to enhance their mitogenic effect on epithelial cells. Here, we proposed a new delivery system to avoid the inhibition of rhEGF by various enzymes, thus improving its bioavailability and sustained release. The amphiphilic polymer was composed of conjugated linoleic acid (CLA) and carboxymethyl chitosan (CMCS), which were further characterized by fourier transformed infrared spectroscopy (FTIR) and
H nuclear magnetic resonance (
H NMR). Then, the self-assembly behavior of CLA-CMCS (CC) polymer in water was observed in which the particle size of CC decreased from 196 to 155 nm with the degree of CLA substitution increasing. The nanoparticles were loaded with rhEGF and the maximum rhEGF loading efficiency (LE) of CC3 nanoparticles was 82.43 ± 3.14%. Furthermore, CC nanoparticles (NPs) exhibited no cytotoxicity for L929 cells, and cell proliferation activity was well preserved after rhEGF loading to CC-NPs and was comparable to that of free rhEGF. Topically applied rhEGF:CC-NPs significantly accelerated the wound-closure rate in full thickness, which was most probably due to its sustained release and enhanced skin permeation. In conclusion, carboxymethyl chitosan-based nanoparticles were constructed and showed good cytocompatibility. Moreover, these findings also demonstrated the therapeutic potential of rhEGF:CC-NPs as a topical wound-healing drug carrier.
•The influence of soil aggregate characteristics on the Tc was investigated.•Tc was significantly correlated to WSA0.25 using the LB-WS method.•The new equations, including WSA0.25, were developed to ...predict the Tc.
The sediment transport capacity of overland flow is the core input variable of a process-based soil erosion model. Many studies have focused on the sediment transport capacity for overland flow; however, few studies have explored the relationship between sediment transport capacity and soil aggregate characteristics. The objective of this study was to investigate the effects of soil aggregate characteristics on the sediment transport capacity of overland flow. The unit flow discharge ranged from 0.68 × 10−3 m2 s−1 to 5.41 × 10−3 m2 s−1, and the slope gradient varied from 5.24% to 26.80%. Five types of typical Chinese soil were investigated. The results showed that the best correlation was the relationship between the sediment transport capacity and the mass percentage of aggregates greater than 0.25 mm (WSA0.25) under the Le Bissonnais method of wetting stirring conditions. Sediment transport capacity was not correlated to the other soil aggregate characteristics, including the mean weight diameter (MWD) under the Le Bissonnais method of fast wetting and slow wetting conditions and the Yoder method, the degree of aggregation (A), and the fractal dimension (D) under the Yoder method. New equations including WSA0.25 were developed to predict the sediment transport capacity. The equation including flow discharge, slope gradient and WSA0.25 provided the best accuracy for predicting sediment transport capacity. The sediment transport capacity increased linearly with the mean flow velocity. Between the hydraulic variables of shear stress and stream power, our results showed that stream power was an optimal predictor for calculating sediment transport capacity. These findings offer a new approach for predicting the sediment transport capacity of overland flow.
The creep resistance of polymer determines the dimensional stability of product under stress. The isotactic polybutene-1 (iPB) with outstanding high-temperature creep resistance and stress-crack ...resistance is applied widely in the field of hot-water pipes. Although the chain information including weight-average molecular weight (Mw) and aggregate structures of isotactic polybutene-1 (iPB) influence the creep resistance, the crucial factor affecting the creep behavior greatly is unclear. In this work, a series PB samples with varied Mw, isotacticity and configurational sequence were synthesized and characterized based on Gel Permeation Chromatography (GPC), solvent fractionation and Nuclear Magnetic Resonance Spectroscopy (NMR). The Differential Scanning Calorimetry (DSC), Wide-angle X-ray diffraction (WAXD) and Small angle X-ray scattering (SAXS) were used to characterize the aggregation structures of PB samples. The stress-strain behaviors and 95 °C creep deformation of these PB samples were testes by tensile test and Dynamic Mechanical Analysis (DMA), respectively. It was found that these PB samples showed different chain microstructures like 88–99 wt% high isotactic PB (HiPB) fractions, 90–97.6 mol% tetra-meso placements (mmmm) in HiPB fraction, and 50 × 104-160 × 104Mw. Increasing the molecular weight, isotacticity or configurational sequence mmmm enhanced the creep resistance of PB, while mmmm configurational sequence played more important role in creep resistance of PB through adjusting the aggregation structure (crystalline domains) of the final product greatly. Exploring the influencing factors of creep resistance provided guidance for the synthesis of high-performance PB for high-temperature pipe application.
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•The effects of molecular weight on high-temperature creep resistance were investigated.•The effects of chain microstructure on high-temperature creep resistance were investigated.•The crucial factor which determines the creep behavior of polybutene was put forward.•The mechanism in molecular level was proposed to clarify the creep behavior of PB-1.
Abstract On-demand dissolution of hydrogels has shown much potential in easy and pain-free removal of wound dressings. This work firstly describes a type of carbon dots (CDs) for dissolving ...Ca-alginate hydrogel via site-specific mineralization method. The CDs were characterized by two features, which included presence of primary/secondary amine groups and generation of calcium crystals with Ca 2+ . Especially, the amount of primary/secondary amine groups on CDs played key role in determining whether hydrogel could be dissolved. When there were sufficient primary/secondary amine groups, the mineralization occurred on CDs rather than alginates due to the hydrogen bond between primary/secondary amine and carboxyl of alginates. Thereby, this promoted the gel-sol transition through Ca 2+ capture from the hydrogels. Moreover, antibacterial test revealed Ca 2+ capture from cell walls, while in vivo test revealed hypoxia relief due to porous structures of the renewed hydrogels. Overall, CDs with sufficient primary/secondary amine groups could dissolve Ca-alginate hydrogel through site-specific mineralization method, accompanying by additional functions of antibacterial and hypoxia relief. Graphical Abstract
Herein reported is a fundamentally new strategy for the design of high-power and high energy-density devices. This approach is based on the exchange of lithium ions between the surfaces (not the ...bulk) of two nanostructured electrodes, completely obviating the need for lithium intercalation or deintercalation. In both electrodes, massive graphene surfaces in direct contact with liquid electrolyte are capable of rapidly and reversibly capturing lithium ions through surface adsorption and/or surface redox reaction. These devices, based on unoptimized materials and configuration, are already capable of storing an energy density of 160 Wh/kgcell, which is 30 times higher than that (5 Wh/kgcell) of conventional symmetric supercapacitors and comparable to that of Li-ion batteries. They are also capable of delivering a power density of 100 kW/kgcell, which is 10 times higher than that (10 kW/kgcell) of supercapacitors and 100 times higher than that (1 kW/kgcell) of Li-ion batteries.
While aldehydes represent a classic class of electrophilic synthons, the corresponding acyl radicals are inherently nucleophilic, which exhibits umpolung reactivity. Generation of acyl radicals ...typically requires noble metal catalysts or excess oxidants to be added. Herein, we report a convenient and green approach to access acyl radicals, capitalizing on neutral eosin Y-enabled hydrogen atom transfer (HAT) photocatalysis with aldehydes. The generated acyl radicals underwent SOMOphilic substitutions with various functionalized sulfones (X-SO
R') to deliver value-added acyl products. The merger of eosin Y photocatalysis and sulfone-based SOMOphiles provides a versatile platform for a wide array of aldehydic C-H functionalizations, including fluoromethylthiolation, arylthiolation, alkynylation, alkenylation and azidation. The present protocol features green characteristics, such as being free of metals, harmful oxidants and additives; step-economic; redox-neutral; and amenable to scale-up assisted by continuous-flow technology.
A concise, protecting‐group‐free total synthesis of the unusual brominated sesquiterpene aplydactone is described. Our synthesis features a 2+2 photocycloaddition, a Wolff ring contraction, an ...unusual remote C−H functionalization to establish the highly strained tetracyclic core, and a hydrogen‐atom transfer (HAT) reaction to access the bromine‐containing stereocenter. A finely tuned conformation of the α‐diazoketone precursor is the key for the success of the late‐stage transannular C−H insertion to deliver a bridged six‐membered ring and a quaternary stereocenter (C6) between two quaternary carbon atoms (C1 and C7).
HAT in hand: A concise, protecting‐group‐free total synthesis of aplydactone has been achieved. The synthesis features a transannular six‐membered‐ring C−H insertion and a hydrogen atom transfer (HAT) reaction. A finely tuned conformation, as supported by theoretical calculations, is key to the success of the challenging C−H insertion.
Demand uncertainty, economic globalization, and environmental deterioration force factories to innovate their manufacturing systems for achieving sustainable performance. Seru production, which is ...the latest manufacturing mode developed in Japan, attracts broad attention from both academia and practitioners. The overwhelming majority of existing works on seru production focus on economic performance unilaterally, while neglecting the environmental and social performance. This paper investigates the effects of key enabling technologies for seru production on sustainable performance. Firstly, four key enabling technologies for seru production are identified through systematic review, and an evaluation indicator system of sustainable performance in the context of seru production is developed. Then, the hypotheses about the effects of the identified key enabling technologies for seru production on sustainable performance are proposed on the basis of previous research achievements, theoretical analysis, and practical observations. Finally, the hypotheses are tested through structural equation modeling. Except for two hypotheses which are not supported and one which is indirectly supported, all other hypotheses are verified. The research results show that the four key enabling technologies for seru production have different effects on the three dimensions of sustainable performance. The achievements of this work are of significance to improve the comprehensive understanding of seru production, as well as to develop practical methods to implement sustainable operations.
•Identified four key enabling technologies for seru production by systematic review.•Developed an evaluation indicator system of sustainable performance in the context of seru production.•Verified the effects of four key enabling technologies for seru production on sustainable performance.
Herein reported is a fundamentally new strategy for reviving rechargeable lithium (Li) metal batteries and enabling the emergence of next-generation safe batteries featuring a graphene-supported Li ...metal anode, including the highly promising Li-sulfur, Li-air, and Li-graphene cells with exceptionally high energy or power densities. All the Li metal anode-based batteries suffer from a high propensity to form Li dendrites (tree-like structures) at the anode upon repeated discharges/charges. A dendrite could eventually penetrate through the separator to reach the cathode, causing internal short-circuiting and even explosion, the main reason for the battery industry to abandon rechargeable lithium metal batteries in the early 1990s. By implementing graphene sheets to increase the anode surface areas, one can significantly reduce the anode current density, thereby dramatically prolonging the dendrite initiation time and decreasing the growth rate of a dendrite, if ever initiated, possibly by a factor of up to 1010 and 105, respectively.
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