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Mesoscale eddies occur frequently in the Luzon Strait and its adjacent area, and accurate prediction of eddy structure changes is of great significance. In recent years, artificial neural network (ANN) has been widely applied in t...
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Mesoscale eddies occur frequently in the Luzon Strait and its adjacent area, and accurate prediction of eddy structure changes is of great significance. In recent years, artificial neural network (ANN) has been widely applied in the study of physical oceanography with the continuous accumulation of satellite remote sensing data. This study adopted an ANN approach to predict the evolution of eddies around the Luzon Strait, based on 25 years of sea level anomaly (SLA) data, 85% of which are used for training and the remaining 15% are reserved for testing. The original SLA data were firstly decomposed into spatial modes (EOFs) and time-dependent principal components (PCs) by the empirical orthogonal function (EOF) analysis. In order to calculate faster and save costs, only the first 35 PCs were selected as predictors, whereas their variance contribution rate reached 96%. The results of predicted reconstruction indicated that the neural network-based model can reliably predict eddy structure evaluations for about 15 days. Importantly, the position and variation of four typical eddy events were reconstructed, and included a cyclone eddy event, an eddy shedding event, an anticyclone eddy event, and an abnormal anticyclone eddy event.
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Mitigating climate change requires long-term global efforts. The aim of this study is to simulate the possible paths of CO2 emissions in G20 countries and the world from 2020 to 2050, by using the STIRPAT model and SSP scenarios w...
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Mitigating climate change requires long-term global efforts. The aim of this study is to simulate the possible paths of CO2 emissions in G20 countries and the world from 2020 to 2050, by using the STIRPAT model and SSP scenarios with different constraints (SSP baseline, SSP-3.4). The results show that (1) the world’s CO2 emissions cannot peak in the SSP baseline scenarios, but can peak in the SSP-3.4 scenarios through four paths other than the high fossil energy consumption path; (2) for G20 countries, in the SSP baseline scenarios, 13 countries such as China, the United States, and the United Kingdom can achieve the peak, while six countries such as Argentina, India, and Saudi Arabia cannot. In the SSP-3.4 scenarios, Saudi Arabia cannot achieve the peak, while other countries can achieve the peak, and most of them are likely to achieve significant CO2 emission reductions by 2050; (3) climate goals have a crowding-out effect on other sustainable development goals, with less impact on developed countries and a greater impact on developing countries; and (4) the optimization of the energy structure and a low energy intensity can greatly advance the peak time of CO2 emissions.
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Solar-driven CO2 reduction to solar fuel is an effective way to deal with the greenhouse effect and energy crisis. A one-step hydrothermal method was used to synthesize Bi4Ti3O12/SrTiO3 composite photocatalysts. The heterogeneous ...
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Solar-driven CO2 reduction to solar fuel is an effective way to deal with the greenhouse effect and energy crisis. A one-step hydrothermal method was used to synthesize Bi4Ti3O12/SrTiO3 composite photocatalysts. The heterogeneous structure formed by intimate contact was observed between SrTiO3 (STO) nanoparticles and Bi4Ti3O12 (BTO) nanoplates, achieving an enhanced photocatalytic CO2 reduction yield of CO (13.37 mu mol/g) that was 5.74-fold that of pure STO (2.33 mu mol/g), with a high yield of CH4 (1.55 mu mol/g). Characterizations of phase composition, morphology, and optical/electrochemical properties were applied to prove the heterojunction structure and its role in improving the photocatalytic performance. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy tests demonstrate that electrons transfer from STO to BTO and result in the generation of an internal electron field between the two phases. Consequently, a direct Z-scheme system was formed: photoelectrons in the conduction band of BTO transferred to the valence band of STO to recombine with the holes thus spatially separated the photogenerated electron-hole pairs while enabling the photocatalyst to achieve the maximum reduction and oxidation capability. The catalyst structure system proposed here may bring new ideas for the development of titanate-based photocatalysts with high CO2 reduction activity. (C) 2021 Society of Photo-Optical Instrumentation Engineers (SPIE)
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When the under-actuated hand pinches the object on the worktable, the trajectory of the end of the finger is not a straight line, which makes it difficult for the hand to grasp the object from its both sides. In order to overcome ...
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When the under-actuated hand pinches the object on the worktable, the trajectory of the end of the finger is not a straight line, which makes it difficult for the hand to grasp the object from its both sides. In order to overcome this shortcoming, this paper proposes a new configuration of the linear-parallel and self-adaptive under-actuated hand which uses the four-link and sliding base mechanism to compensate for the vertical displacement of the end of the finger. Based on this new configuration, the mechanical structure of the under-actuated hand is designed, which has five degrees of freedom (DOFs), and is mainly composed of two fingers, a sliding base, four link compensation mechanisms and an outer base. These two fingers have exactly the same structure and size, where each finger uses only one motor to control two joints of the finger which realizes the under-actuated function. Through the cooperation of the four-link and sliding base mechanism, the under-actuated hand can realize the linear-parallel and self-adaptive hybrid grasping mode. Kinematics analysis and contact force analysis of the under-actuated hand are discussed, and the prototype of the under-actuated hand is developed to carry out the grasping experiments. The results of the simulation and experiment all show that the under-actuated hand has good motion performance and grasping stability and can be used as an end effector for intelligent robots.
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The response of dam structures subjected to explosion shock loading is a key element in assessments for the dam antiknock safety and antiterrorism applications. The physical processes during an explosive detonated in underwater/ai...
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The response of dam structures subjected to explosion shock loading is a key element in assessments for the dam antiknock safety and antiterrorism applications. The physical processes during an explosive detonated in underwater/air and the subsequent response of structures are extremely complex, involving many complex issues such as the explosion, shock wave propagation, shock wave-structure interaction, and structural response. In addition, there exists a significant contrast in wave propagation phenomena in the water and the air medium due to their different physical properties and interface phenomena. In this paper, a fully coupled numerical approach with combined Lagrangian and Eulerian methods is used to simulate the dynamic responses of a concrete gravity dam subjected to underwater and air explosions. The shock wave propagation characteristics from explosions in water and air are simulated and compared. The damage profiles of concrete gravity dams subjected to underwater and air explosions are discussed. The influence of the blast loading from explosions in water and air on the dynamic response and the damage of the dam is also investigated. The analysis results show that a submerged explosion causes significantly more damage to the dam in water than the same mass of explosive in air. (C) 2014 American Society of Civil Engineers.
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The ankle joint complex (AJC) is of fundamental importance for balance, support, and propulsion. However, it is particularly susceptible to musculoskeletal and neurological injuries, especially neurological injuries such as drop f...
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The ankle joint complex (AJC) is of fundamental importance for balance, support, and propulsion. However, it is particularly susceptible to musculoskeletal and neurological injuries, especially neurological injuries such as drop foot following stroke. An important factor in ankle dysfunction is damage to the central nervous system (CNS). Correspondingly, the fundamental goal of rehabilitation training is to stimulate the reorganization and compensation of the CNS, and to promote the recovery of the motor system’s motor perception function. Therefore, an increasing number of ankle rehabilitation robots have been developed to provide long-term accurate and uniform rehabilitation training of the AJC, among which the parallel ankle rehabilitation robot (PARR) is the most studied. The aim of this study is to provide a systematic review of the state of the art in PARR technology, with consideration of the mechanism configurations, actuator types with different trajectory tracking control techniques, and rehabilitation training methods, thus facilitating the development of new and improved PARRs as a next step towards obtaining clinical proof of their rehabilitation benefits. A literature search was conducted on PubMed, Scopus, IEEE Xplore, and Web of Science for articles related to the design and improvement of PARRs for ankle rehabilitation from each site’s respective inception from January 1999 to September 2020 using the keywords “ parallel”, “ ankle”, and “ robot”. Appropriate syntax using Boolean operators and wildcard symbols was utilized for each database to include a wider range of articles that may have used alternate spellings or synonyms, and the references listed in relevant publications were further screened according to the inclusion criteria and exclusion criteria. Ultimately, 65 articles representing 16 unique PARRs were selected for review, all of which have developed the prototypes with experiments designed to verify their usability and feasibility. From the comparison among these PARRs, we found that there are three main considerations for the mechanical design and mechanism optimization of PARRs, the choice of two actuator types including pneumatic and electrically driven control, the covering of the AJC’s motion space, and the optimization of the kinematic design, actuation design and structural design. The trajectory tracking accuracy and interactive control performance also need to be guaranteed to improve the effect of rehabilitation training and stimulate a patient’s active participation. In addition, the parameters of the reviewed 16 PARRs are summarized in detail with their differences compared by using figures and tables in the order they appeared, showing their differences in the two main actuator types, four exercise modes, fifteen control strategies, etc., which revealed the future research trends related to the improvement of the PARRs. The selected studies showed the rapid development of PARRs in terms of their mechanical designs, control strategies, and rehabilitation training methods over the last two decades. However, the existing PARRs all have their own pros and cons, and few of the developed devices have been subjected to clinical trials. Designing a PARR with three degrees of freedom (DOFs) and whereby the mechanism’s rotation center coincides with the AJC rotation center is of vital importance in the mechanism design and optimization of PARRs. In addition, the design of actuators combining the advantages of the pneumatic-driven and electrically driven ones, as well as some new other actuators, will be a research hotspot for the development of PARRs. For the control strategy, compliance control with variable parameters should be further studied, with sEMG signal included to improve the real-time performance. Multimode rehabilitation training methods with multimodal motion intention recognition, real-time online detection and evaluation system should also be further developed to meet the needs of different ankle disability and rehabilitation stages. In addition, the clinical trials are in urgent need to help the PARRs be implementable as an intervention in clinical practice.
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Macrophages (M Phi s) are an important immune cell population that are essential for tissue homeostasis and disease pathogenesis. M Phi s are now classified as either M1, which produce pro-inflammatory cytokines, or M2, which prod...
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Macrophages (M Phi s) are an important immune cell population that are essential for tissue homeostasis and disease pathogenesis. M Phi s are now classified as either M1, which produce pro-inflammatory cytokines, or M2, which produce antiinflammatory cytokines. The impact of granulocyte colony-stimulating factor (G-CSF) on M Phi s in humans is unclear. Moreover, little is known about the association between M Phi subsets in allografts and the occurrence of acute graft-versushost disease (aGVHD) in patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). In the current study, we found that the M1/M2 ratio was markedly decreased in both G-CSF-treated bone marrow (post-BM) and G-CSF-treated peripheral blood from healthy donors. Post-BM M Phi s exhibited reduced migration and increased phagocytosis. Moreover, post-BM M Phi s reduced the percentage of Th1 and Tc1 lineages and increased the percentage of Th2, Tc2, and Treg lineages. Patients who received BM grafts with a higher M1/M2 ratio exhibited a higher incidence of grade 2-4 aGVHD. In summary, our data indicate that G-CSF decreases the M1/M2 ratio in BM grafts from healthy donors, which may contribute to preventing the occurrence of grade 2-4 aGVHD in patients after allo-HSCT.
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The pathogenesis of corticosteroid-resistant immune thrombocytopenia (ITP), a clinically challenging condition in which patients exhibit either no response to corticosteroids or are corticosteroid-dependent, remains poorly underst...
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The pathogenesis of corticosteroid-resistant immune thrombocytopenia (ITP), a clinically challenging condition in which patients exhibit either no response to corticosteroids or are corticosteroid-dependent, remains poorly understood. Murine studies suggest that bone marrow (BM) endothelial progenitor cells (EPCs) play a crucial role in regulating megakaryocytopoiesis. However, little is known regarding the number and function of BM EPCs or how to improve impaired BM EPCs in corticosteroid-resistant ITP patients. In the current case-control study, we evaluated whether the BM EPCs in corticosteroid-resistant ITP differed from those in corticosteroid-sensitive ITP. Moreover, whether atorvastatin could enhance the number and function of BM EPCs derived from corticosteroid-resistant ITP patients was investigated in vitro and in vivo. Reduced and dysfunctional BM EPCs, characterized by decreased capacities of migration and angiogenesis as well as higher levels of reactive oxygen species and apoptosis, were observed in corticosteroid-resistant ITP patients. In vitro treatment with atorvastatin quantitatively and functionally improved BM EPCs derived from corticosteroid-resistant ITP patients by downregulating the p38 MAPK pathway and upregulating the Akt pathway, and rescued the impaired BM EPCs to support megakaryocytopoiesis. Subsequently, a pilot cohort study showed that atorvastatin was safe and effective in corticosteroid-resistant ITP patients. Taken together, these results indicate that reduced and dysfunctional BM EPCs play a role in the pathogenesis of corticosteroid-resistant ITP, and the impaired BM EPCs could be improved by atorvastatin both in vitro and in vivo. Although requiring further validation, our data indicate that atorvastatin represents a promising therapeutic approach for repairing impaired BM EPCs in corticosteroid-resistant ITP patients.
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Modified Mg3Al layered double hydroxide (LDH) intercalated with dodecylsulfate anion composites, which were designated as SDS-LDH composites, were synthesized by coprecipitation. The samples were characterized using SEM, EDX, FT-I...
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Modified Mg3Al layered double hydroxide (LDH) intercalated with dodecylsulfate anion composites, which were designated as SDS-LDH composites, were synthesized by coprecipitation. The samples were characterized using SEM, EDX, FT-IR, zeta potential analysis, and XRD. The results showed that the SDS-LDH composites contain a thicker and larger porous interconnected network than inorganic LDH due to the enlarged inter-layer distance. The outstanding adsorption performance of SDS-LDH composites toward 17-estradiol (E2) was investigated under different conditions, including solution pH, adsorbent dosage, ion strength, reaction time, and temperature. When the solution pH was 7 and the adsorbent dosage was 2 g L-1, the removal rate of E2 reached the maximum at 94%, whereas inorganic LDH displayed a poor E2 removal rate of 10%. The presence of various ions (Na+, SO42-, CI-, and H2PO4-) in aqueous solution exerted no significant adverse effects on the adsorption process. The adsorption equilibrium was reached within 20 min, and the adsorption fitted well with the pseudo-second-order model and the Freundlich isotherm. The thermodynamic test revealed that the adsorption process was spontaneous and endothermic. Phosphorus was selected as the index for evaluating the adsorption capacity of SDS-LDH composites for inorganic ions. The removal rates of total phosphorus and PO43- were 43.71% and 55.93% for SDS-LDH composites at 2 g L-1. The removal rate of PO43- reached up to 85% when the contact time was 120 min and the dosage was 3 g L-1 for SDS-LDH composites, which were approximately close to those of inorganic LDH of 30 min and 2 g L-1, respectively. This finding indicates that the removal capacity of SDS-LDH composites for PO43- decreased after the dodecylsulfate anions intercalated into the interlayer. The composites retained their high efficiency and stability after desorption and regeneration with alkali treatment. This study demonstrated that SDS-LDH composites are a promising adsorbent for the recovery and abatement of trace-level E2 in secondary effluents of wastewater treatment plants.
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Bi12GeO20-based composites Bi12GeO20-Bi2S3 (BGS) were successfully constructed through a facile ball-milling method using sulfur powder for the first time. Systematical analyses verified the in-situ generation of n-p heterojunctio...
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Bi12GeO20-based composites Bi12GeO20-Bi2S3 (BGS) were successfully constructed through a facile ball-milling method using sulfur powder for the first time. Systematical analyses verified the in-situ generation of n-p heterojunctions with surface oxygen vacancies (OVs). These composites showed reinforced photocatalytic removal of NO at ppb level under visible light with high selectivity for NO2- /NO3- species, avoiding the generation of toxic NO2 as far as possible. Especially, the best candidate BGS0.1 possessed 46% NO removal with 96% selectivity for NO2-/NO3- species that were much higher than those by Bi12GeO20, mainly relevant to the enhanced visible-light absorption, synergistic effect of heterojunctions containing surface OVs to promote charge carriers segregation and reactive radicals formation, and suitable phase composition with proper band structures. The effect of heterojunctions with surface OVs over band structures and reaction paths was demonstrated by density functional theory (DFT) calculation. DRIFTS and FT-IR spectra were recorded to deduce NO conversion routes. Eventually, a preliminary photocatalysis mechanism of these robust composites was conjectured in a Zscheme manner basing experimental and analytical results. This study might pave roads for in-situ construction of sillenite-based composites with surface OVs by a mechanochemical approach with satisfactory photocatalytic NO treatment under visible light.
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