Net primary productivity (NPP) can indicate vegetation ecosystem services ability and reflect variation response to climate change and human activities. This study applied MODIS-1 km NPP products to ...investigate the NPP variation from 2001 to 2006, a fast urban expansion and adjustment period in Guangzhou, China, and quantify the impacts of weather and land use/land cover (LULC) changes, respectively. The results showed that the NPP mean value increased at a rate of 11.6 g∙C∙m−2∙yr−1 during the initial three years and decreased at an accelerated rate of 31.0 g∙C∙m−2∙yr−1 during the final three years, resulting in a total NPP loss of approximately 167 × 106 g∙C. The spatiotemporal of NPP varied obviously in the central area, suburb and exurb of Guangzhou driven by three patterns of weather and LULC changes. By the interactive effects and the weather variation dominated effects, NPP of most areas changed slightly with dynamic index less than 5% of NPP mean value in the central area and the suburb. The LULC change dominated effects caused obvious NPP reduction, by more than 15% of the NPP mean value, which occurred in some areas of the suburb and extended to the exurb with the outward urban sprawl. Importantly, conversion from wood grassland, shrublands and even forests to croplands occupied by urban landscapes proved to be a main process in the conversion from high-NPP coverage to low-NPP coverage, thereby leading to the rapid degradation of urban carbon stock capacity in urban fringe areas. It is helpful for government to monitor urban ecological health and safety and make relevant policies.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Task-specific Py-Zn@IPOPX with multiple active sites are developed and exhibit durable high-activity for cycloaddition of CO2 to epoxides under additive-free conditions.
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•Novel ...task-specific Py-Zn@IPOPX are constructed in green ionic liquid medium.•Py-Zn@IPOPI with multiple active sites can activate CO2 and epoxide simultaneously.•Py-Zn@IPOPI realizes efficient CO2 cycloaddition under additive-free conditions.•The developed catalyst is easily separated and exhibits durable high-activity.
Based on the Schiff base reaction and post-modification strategy, novel nanocomposites of pyridine-zinc-based ionic porous organic polymers (Py-Zn@IPOPX, X = Br, I, Ac) were constructed and structurally characterized. Various Py-Zn@IPOPX were applied to the transformation of CO2 and epoxides into cyclic carbonates, and their catalytic activities were studied and discussed in detail. The results showed that Py-Zn@IPOPI possesses Lewis acid-base bifunctional features, and also modified with superior nucleophilic active groups, which exerted an important synergistic effect on activation of CO2 and epoxide, and ring-opening of epoxide. Under co-catalyst/solvent-free conditions, Py-Zn@IPOPI could afford 96 % PC yield and 99 % selectivity at 120 °C and 2.0 MPa CO2 pressure for 6 h, and turnover frequency (TOF) was high to 230 h−1. Moreover, the reusability and versatility of the catalyst were examined, and the catalytic mechanism was speculated according to the obtained results. Compared with previously reported porous polymer catalysts, Py-Zn@IPOPI requires much greener and milder reaction conditions while avoids the use of a co-catalyst, displaying bright prospects for the design and synthesis of ionic porous organic polymers for CO2 activation and utilization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Satellite networks have long been regarded as a vital component of space communication systems, which provide integrated satellite-terrestrial broadband access in seamless coverage and cost-effective ...manner. The inter-satellite routing design for low earth orbit (LEO) satellite constellations is critical for achieving low-latency and high-reliability communication in the space communication systems. However, the inherent dynamic nature of LEO satellites, coupled with the variability in inter-satellite connectivity, imposes significant challenges for routing efficiency and network dependability. Existing routing schemes cannot handle such topological fluctuations due to their insensitivity to real-time network changes, thus suffering from performance degradations in highly dynamic space environments. This paper presents Iris , an intelligent reliable routing scheme for inter-satellite communication, aiming at increasing efficiency and reliability of the packet transmission process. Specifically, we propose a comprehensive deep reinforcement learning (DRL) framework that learns a policy to select routing paths automatically under the emerging software-defined satellite networking (SDSN) architecture. To strengthen fault-tolerance in fluctuating environments, we train an agent in an incremental manner by gradually increasing scenario complexity. Simulation results indicate that our solution significantly outperforms baselines and exhibits advances in adaptability and reliability, especially under dynamic environments with frequent topology changes.
•SDSN framework can alleviate the dilemma of limited on-planet resources.•Link attributes characterize the impact of satellite dynamics on link reliability.•LAODR can enhance the adaptability and ...reliability during data transmission.•Use NSGA-II to solve the multi-service routing and ensure services adaptation.
As the potential complement to terrestrial networks, satellite networks are expected to facilitate full coverage and broadband access at anytime and anywhere. However, satellite networks are characterized by highly dynamic topology and load, and how to design an adaptive routing algorithm to meet diverse application needs faces significant challenges. In this paper, we propose a Link-Attributes-based multi-service On-Demand Routing (LAODR) algorithm to provide highly reliable and service-aware data forwarding for Software -Defined Satellite Networks (SDSN). Specifically, we construct a quantitative model of link reliability which provides a fine-grained state description of the dynamic topology. Furthermore, we select the K-shortest path as the solution space and plan routing paths based on NSGA-II to allocate link resources reasonably. Extensive experiments on the Iridium validate that LAODR outperforms state-of-art routing algorithms in terms of end-to-end average latency, packet loss, throughput and node congestion degree, as well as meets the requirements of diverse services.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Many students trained in carbon-free trolley engineering to design smoothly but found that it was difficult to achieve the ideal results with a lot of time and effort in trajectory ...debugging. To deeply explore the characteristics of space crank rocker, through repeated experiments and theoretical analysis of carbon-free trolleys, and using MATLAB, SolidWorks, SPSS, and other software analysis, combined with projection geometric analysis to derive the equations of motion and derive the displacement, velocity, and acceleration characteristic curves. The conditions for the existence of the space crank rocker mechanism with an interlaced angle of 90° are derived, and the relationship between corner amplitude and main structural parameters is obtained. The size of the influence factor of each structural parameter was compared. In the commissioning, according to the characteristics of these parameters, the commissioning cycle of the carbon-free trolley can be greatly shortened.
An efficient two-electrode strategy with the amplification of BOD label was first put forward to develop a novel PEC biosensing platform with high sensitivity and good selectivity in real biological ...matrix.
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•An efficient two-electrode strategy amplified by BOD labelling was proposed to build PEC biosensing platform.•The ZIS/Fe:TiO2 photoanode as signal conservation element presented a remarkable photocurrent output.•The BOD-guided signaling strategy for O2 reduction reaction could change current detection signal evidently.•The PEC biosensing platform demonstrated high sensitivity and good selectivity in real biological matrix.
Herein, a novel and robust two-electrode photoelectrochemical (PEC) biosensing platform amplified by bilirubin oxidase (BOD) labelling was reported. This two-electrode operating system was composed of photoanode and sensing biocathode. Carcinoembryonic antigen (CEA) was utilized as a model for probing. Specifically, Fe3+-doped TiO2 (Fe:TiO2) nanotubes were first prepared and then deposited with ZnIn2S4 (ZIS) nanocrystals to develop the ZIS/Fe:TiO2 photoanode. Toward sensing biocathode, after carbon nanotubes (CNTs) and Au nanoparticles (NPs) were modified on conductive glass, an Au/CNT cathodic substrate was fabricated to anchor the CEA aptamer. Complementary DNA (cDNA) of the CEA aptamer was labelled with BOD to form the cDNA-BOD conjugate that amplified the signal through DNA hybridization. Target detection hinged on an evident decline in the current signal generated by terminated amplification of the BOD labels and evident steric hindrance of the captured CEA molecules. Profiting from excellent PEC property of the ZIS/Fe:TiO2 photoanode and good oxygen-reduction capability of the BOD labels, the two-electrode PEC biosensing platform exhibited high sensitivity. Because of the division of biorecognition with photoanode, the platform also showed satisfactory selectivity in biological matrix. This elegant two-electrode strategy offers a promising path for seeking other robust PEC biosensors applying in complex biological samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aberrant expression of annexin A2-SI00A10 heterotetramer （AIIt） associated with PML/RARα fusion protein causes lethal hyperfibrinolysis in acute promyelocytic leukemia （APL）, but the mechanism is ...unclear. To facilitate the investigation of regulatory association between ANXA2 and promyelocytic leukemia/retinoic acid receptor α （PML/RARα） fusion protein, this work was performed to determine the transcription start site of ANXA2 promoter with rapid amplification of 5＇-cDNA ends analysis. Zinc-induced U937/PR9 cells expressed PML/RARα fusion protein, and resultant increases in ANXA2 transcripts and translational expressions of both ANXA2 and S100A10, while S100A10 transcripts remained constitutive. The transactivation of ANXA2 promoter by PML/RARα fusion protein was 3.29 ± 0.13 fold higher than that by control pSG5 vector or wild-type RARer. The overexpression of ANXA2 in U937 transfected with full-length ANXA2 cDNA was associated with increased S100A10 subunit, although S100A10 transcripts remained constitutive. The tPA-dependent initial rate of plasmin generation （IRPG） in zinc-treated U937/PR9 increased by 2.13-fold, and cell invasiveness increased by 27.6%. Antibodies against ANXA2, S100A10, or combination of both all remarkably inhibited the IRPG and invasiveness in U937/PR9 and NB4. Treatment of zinc-induced U937/PR9 or circulating APL blasts with all-trans retinoic acid （ATRA） significantly reduced cell surface ANXA2 and S100A10 and associated reductions in IRPG and invasiveness. Thus, PML/RARα fusion protein transactivated the ANXA2 promoter to upregulate ANXA2 and accumulate S100A10. Increased AIIt promoted IRPG and invasiveness, both of which were partly abolished by antibodies against ANXA2 and S100A10 or by ATRA.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
That GIS-based hydrological response units (HRUs) incorporated watershed variables and their potential spatial correlation into ANN modeling was clarified in the paper. The process and final results ...of neural network modeling were both assessed by the deterministic or statistical methods, spatial regression kriging (RK). The relation of prediction errors and HRUs area scale can provide useful information to optimize the design of stream monitoring network. It is indicated that potential advantage of ANN for watershed and the assessment of estuarine river impacts can be done by precise spatial prediction and sensitive factors analysis.
The low earth orbit (LEO) satellite constellation is regarded as an effective complement to the terrestrial communication system due to its seamless coverage and ultra-low latency. Unfortunately, the ...highly dynamic traffic volume, as well as the inherent nature of dynamic topology changes caused by frequent link handover and uncertain hardware failures, pose severe challenges in the design of reliable routing. However, most existing reliable routing approaches with distributed schemes only focus on information exchange between adjacent nodes, which makes them fail to perceive real-time global network changes and make optimal decisions. In this paper, we propose a software defined networking (SDN) based intelligent satellite routing (SISR) method to increase the adaptivity and reliability during the packet transmission process. With the facilitation of SDN, we manage the network in a hierarchical and centralized paradigm, and further implement a more refined form of reinforcement learning (RL) to enhance the fault-tolerant ability of satellite network routing. Experimental results show that our solution can reduce latency and packet loss ratio by more than 42% and 29% compared to baselines.
Lanthanum-aluminum loaded hydrothermal palygorskite（La-Al-HP） composite was prepared and selected as adsorbent for the fluoride removal from simulated groundwater. The adsorbent was characterized by ...scanning electron microscopy（SEM）, Brunauer-Emmet-Teller（BET） analysis, X-ray diffraction（XRD） analysis and X-ray pho- toelectron spectroscopy（XPS）. SEM visualization shows that the dense surface structure of raw HP appeared loose and presented micro canals after modification. The BET analysis also proved the specific surface area of La-Al-HP composite（95.58 m^2/g） was higher than that of the raw HP（34.31 m^2/g）. Subsequently, the adsorption capacity of La-Al-HP composite was demonstrated in adsorption experiments. The kinetics of fluoride ion adsorption into La-Al-HP composite followed the pseudo-second order with a correlation coefficient of 0.997. The isotherm data was well fitted with the Langmuir model. The monolayer adsorption capacity of La-Al-HP composite was 1.30 mg/g. The XRD and XPS results reveal that the La^3＋ and Al^3＋ ions were loaded on the surface of modified HP and the fluoride ion was adsorbed onto the La-Al-HP composite. A large amount of La-Al-O composite oxide existing on the surface of La-Al-HP composite might be the immanent cause for the excellent adsorption capacity of fluoride ions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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