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The deteriorated degradation resistance of Mg alloy microtubes for vascular stent under the coupling effect of radial compressive stress and dynamic medium
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作者 Mengyao Liu Yabo Zhang +6 位作者 Qingyuan Zhang Yan wang Di Mei Yufeng Sun liguo wang Shijie Zhu Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第2期573-585,共13页
The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environm... The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environment,the hot-extruded fine-grained Mg-Zn-Y-Nd alloy microtubes,which are employed to manufacture vascular stents,were tested under radial compressive stress in the dynamic Hanks'Balanced Salt Solution(HBSS).The results revealed that the high flow rate accelerates the degradation of Mg alloy microtubes and its degradation is sensitive to radial compressive stress.These results contribute to understanding the service performance of Mg alloys as vascular stent materials. 展开更多
关键词 Mg alloy MICROTUBES Degradation behavior Radial compressive stress Dynamic conditions
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A multi-functional MgF_(2)/polydopamine/hyaluronan-astaxanthin coating on the biodegradable ZE21B alloy with better corrosion resistance and biocompatibility for cardiovascular application
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作者 Yachen Hou Xueqi Zhang +2 位作者 Jingan Li liguo wang Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第3期1102-1116,共15页
The cardiovascular diseases(CVD)continue to be the major threat to global public health over the years,while one of the effective methods to treat CVD is stent intervention.Biomedical magnesium(Mg)alloys have great po... The cardiovascular diseases(CVD)continue to be the major threat to global public health over the years,while one of the effective methods to treat CVD is stent intervention.Biomedical magnesium(Mg)alloys have great potential applications in cardiovascular stents benefit from their excellent biodegradability and absorbability.However,excessive degradation rate and the delayed surface endothelialization still limit their further application.In this study,we modified a Mg-Zn-Y-Nd alloy(ZE21B)by preparing MgF_(2) as the corrosion resistance layer,the dopamine polymer film(PDA)as the bonding layer,and hyaluronic acid(HA)loaded astaxanthin(ASTA)as an important layer to directing the cardiovascular cells fate.The electrochemical test results showed that the MgF_(2)/PDA/HA-ASTA coating improved the corrosion resistance of ZE21B.The cytocompatibility experiments also demonstrated that this novel composite coating also selectively promoted endothelial cells proliferation,inhibited hyperproliferation of smooth muscle cells and adhesion of macrophages.Compared with the HAloaded rapamycin(RAPA)coating,our MgF_(2)/PDA/HA-ASTA coating showed better blood compatibility and cytocompatibility,indicating stronger multi-functions for the ZE21B alloy on cardiovascular application. 展开更多
关键词 Biodegradable ZE21B alloy REENDOTHELIALIZATION Surface modification Hyaluronic acid Astaxanthin.
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The misalignment between degradation rate and mechanical integrity of Mg-Zn-Y-Nd alloy during the degradation evaluation in modified Hanks’solutions
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作者 Di Mei Qingyuan Zhang +7 位作者 Yaqian Li Mengyao Liu Wenkai Li Pingli Jiang Ruiqing Hou Shijie Zhu liguo wang Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第9期3661-3674,共14页
The degradation behavior of biodegradable Mg alloys has become a research hotspot in the fields about biodegradable metallic materials.While the most of the related publications mainly focused on the degradation rate ... The degradation behavior of biodegradable Mg alloys has become a research hotspot in the fields about biodegradable metallic materials.While the most of the related publications mainly focused on the degradation rate of Mg-based materials,but rare to care about the changes of their mechanical properties during the immersion period,which can significantly affect their service performance.The link between residual strength and Mg degradation is not appreciated enough.In this work,a series media were constructed based on Hanks’solution,the effects of inorganic ions on the degradation rate and mechanical integrity of Mg-Zn-Y-Nd alloy were investigated.The results indicated that the degradation behavior of Mg alloy was mainly controlled by degradation products and there is no direct correspondence between the degradation rate change and mechanical integrity of Mg alloy.The relevant findings are beneficial for selecting the monitoring index in Mg corrosion tests and evaluating the service reliability of Mg alloys for biomedical applications. 展开更多
关键词 Magnesium alloy Degradation rate Mechanical integrity Hanks’solution
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Privacy‐preserving remote sensing images recognition based on limited visual cryptography 被引量:3
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作者 Denghui Zhang Muhammad Shafiq +2 位作者 liguo wang Gautam Srivastava Shoulin Yin 《CAAI Transactions on Intelligence Technology》 SCIE EI 2023年第4期1166-1177,共12页
With the arrival of new data acquisition platforms derived from the Internet of Things(IoT),this paper goes beyond the understanding of traditional remote sensing technologies.Deep fusion of remote sensing and compute... With the arrival of new data acquisition platforms derived from the Internet of Things(IoT),this paper goes beyond the understanding of traditional remote sensing technologies.Deep fusion of remote sensing and computer vision has hit the industrial world and makes it possible to apply Artificial intelligence to solve problems such as automatic extraction of information and image interpretation.However,due to the complex architecture of IoT and the lack of a unified security protection mechanism,devices in remote sensing are vulnerable to privacy leaks when sharing data.It is necessary to design a security scheme suitable for computation‐limited devices in IoT,since traditional encryption methods are based on computational complexity.Visual Cryptography(VC)is a threshold scheme for images that can be decoded directly by the human visual system when superimposing encrypted images.The stacking‐to‐see feature and simple Boolean decryption operation make VC an ideal solution for privacy‐preserving recognition for large‐scale remote sensing images in IoT.In this study,the secure and efficient transmission of high‐resolution remote sensing images by meaningful VC is achieved.By diffusing the error between the encryption block and the original block to adjacent blocks,the degradation of quality in recovery images is mitigated.By fine‐tuning the pre‐trained model from large‐scale datasets,we improve the recognition performance of small encryption datasets for remote sensing images.The experimental results show that the proposed lightweight privacy‐preserving recognition framework maintains high recognition performance while enhancing security. 展开更多
关键词 activity recognition feature extraction image classification KNN privacy protection remote monitoring remote sensing
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A complementary integrated Transformer network for hyperspectral image classification
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作者 Diling Liao Cuiping Shi liguo wang 《CAAI Transactions on Intelligence Technology》 SCIE EI 2023年第4期1288-1307,共20页
In the past,convolutional neural network(CNN)has become one of the most popular deep learning frameworks,and has been widely used in Hyperspectral image classification tasks.Convolution(Conv)in CNN uses filter weights... In the past,convolutional neural network(CNN)has become one of the most popular deep learning frameworks,and has been widely used in Hyperspectral image classification tasks.Convolution(Conv)in CNN uses filter weights to extract features in local receiving domain,and the weight parameters are shared globally,which more focus on the highfrequency information of the image.Different from Conv,Transformer can obtain the long‐term dependence between long‐distance features through modelling,and adaptively focus on different regions.In addition,Transformer is considered as a low‐pass filter,which more focuses on the low‐frequency information of the image.Considering the complementary characteristics of Conv and Transformer,the two modes can be integrated for full feature extraction.In addition,the most important image features correspond to the discrimination region,while the secondary image features represent important but easily ignored regions,which are also conducive to the classification of HSIs.In this study,a complementary integrated Transformer network(CITNet)for hyperspectral image classification is proposed.Firstly,three‐dimensional convolution(Conv3D)and two‐dimensional convolution(Conv2D)are utilised to extract the shallow semantic information of the image.In order to enhance the secondary features,a channel Gaussian modulation attention module is proposed,which is embedded between Conv3D and Conv2D.This module can not only enhance secondary features,but suppress the most important and least important features.Then,considering the different and complementary characteristics of Conv and Transformer,a complementary integrated Transformer module is designed.Finally,through a large number of experiments,this study evaluates the classification performance of CITNet and several state‐of‐the‐art networks on five common datasets.The experimental results show that compared with these classification networks,CITNet can provide better classification performance. 展开更多
关键词 complementary integrated Transformer module convolutional neural network Gaussian modulation TRANSFORMER
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An efficient and stable Cu/SiO_2 catalyst for the syntheses of ethylene glycol and methanol via chemoselective hydrogenation of ethylene carbonate 被引量:7
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作者 Jiaju Liu Peng He +3 位作者 liguo wang Hui Liu Yan Cao Huiquan Li 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第8期1283-1293,共11页
The efficient synthesis of methanol and ethylene glycol via the chemoselective hydrogenation of ethylene carbonate(EC) is important for the sustainable utilization of CO_2 to produce commodity chemicals and fuels. I... The efficient synthesis of methanol and ethylene glycol via the chemoselective hydrogenation of ethylene carbonate(EC) is important for the sustainable utilization of CO_2 to produce commodity chemicals and fuels. In this work, a series of β-cyclodextrin-modified Cu/SiO_2 catalysts were prepared by ammonia evaporation method for the selective hydrogenation of EC to co-produce methanol and ethylene glycol. The structure and physicochemical properties of the catalysts were characterized in detail by N_2 physisorption, XRD, N_2O titration, H_2-TPR, TEM, and XPS/XAES. Compared with the unmodified 25 Cu/SiO_2 catalyst, the involvement of β-cyclodextrin in 5β-25 Cu/SiO_2 could remarkably increase the catalytic activity—excellent activity of 1178 mgEC g_(cat)^(–1) h^(–1) with 98.8%ethylene glycol selectivity, and 71.6% methanol selectivity could be achieved at 453 K. The remarkably improved recyclability was primarily attributed to the remaining proportion of Cu~+/(Cu^0+Cu~+). Furthermore, the DFT calculation results demonstrated that metallic Cu^0 dissociated adsorbed H_2, while Cu~+ activated the carbonyl group of EC and stabilized the intermediates. This study is a facile and efficient method to prepare highly dispersed Cu catalysts—this is also an effective and stable heterogeneous catalyst system for the sustainable synthesis of ethylene glycol and methanol via indirect chemical utilization of CO_2. 展开更多
关键词 Ethylene carbonate Hydrogenation Β-CYCLODEXTRIN Cu/SiO2 Methanol Ethylene glycol
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Recent advances on the reduction of CO2 to important C2+ oxygenated chemicals and fuels 被引量:5
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作者 Jiachen Li liguo wang +3 位作者 Yan Cao Chanjuan Zhang PengHe Huiquan Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第11期2266-2279,共14页
The chemical utilization of CO_2 is a crucial step for the recycling of carbon resource. In recent years, the study on the conversion of CO_2 into a wide variety of C_(2+) important chemicals and fuels has received co... The chemical utilization of CO_2 is a crucial step for the recycling of carbon resource. In recent years, the study on the conversion of CO_2 into a wide variety of C_(2+) important chemicals and fuels has received considerable attention as an emerging technology. Since CO_2 is thermodynamically stable and kinetically inert, the effective activation of CO_2 molecule for the selective transformation to target products still remains a challenge. The welldesigned CO_2 reduction route and efficient catalyst system has imposed the feasibility of CO_2 conversion into C_(2+) chemicals and fuels. In this paper, we have reviewed the recent advances on chemical conversion of CO_2 into C_(2+) chemicals and fuels with wide practical applications, including important alcohols, acetic acid, dimethyl ether, olefins and gasoline. In particular, the synthetic routes for C\\C coupling and carbon chain growth, multifunctional catalyst design and reaction mechanisms are exclusively emphasized. 展开更多
关键词 CO2 REDUCTION C2+ CHEMICALS Fuels CATALYSIS
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Integrated watershed management:evolution,development and emerging trends 被引量:4
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作者 Guangyu wang Shari Mang +4 位作者 Haisheng Cai Shirong Liu Zhiqiang Zhang liguo wang John L.Innes 《Journal of Forestry Research》 SCIE CAS CSCD 2016年第5期967-994,共28页
Watershed management is an ever-evolving practice involving the management of land, water, biota, and other resources in a defined area for ecological, social, and economic purposes. In this paper, we explore the foll... Watershed management is an ever-evolving practice involving the management of land, water, biota, and other resources in a defined area for ecological, social, and economic purposes. In this paper, we explore the following questions: How has watershed management evolved? What new tools are available and how can they be integrated into sustainable watershed management? To address these questions, we discuss the process of developing integrated watershed management strategies for sustainable manage- ment through the incorporation of adaptive management techniques and traditional ecological knowledge. We address the numerous benefits from integration acrossdisciplines and jurisdictional boundaries, as well as the incorporation of technological advancements, such as remote sensing, GIS, big data, and multi-level social-eco- logical systems analysis, into watershed management strategies. We use three case studies from China, Europe, and Canada to review the success and failure of integrated watershed management in addressing different ecological, social, and economic dilemmas in geographically diverse locations. Although progress has been made in watershed management strategies, there are still numerous issues impeding successful management outcomes; many of which can be remedied through holistic management approaches, incorporation of cutting-edge science and technology, and cross-jurisdictional coordination. We conclude by high- lighting that future watershed management will need to account for climate change impacts by employing techno- logical advancements and holistic, cross-disciplinary approaches to ensure watersheds continue to serve their ecological, social, and economic functions. We present three case studies in this paper as a valuable resource for scientists, resource managers, government agencies, and other stakeholders aiming to improve integrated watershed management strategies and more efficiently and successfully achieve ecological and socio-economic management objectives. 展开更多
关键词 Adaptive management Climate change impacts Social-ecological systems analysis Traditional ecological knowledge Watershed management
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The adsorption properties of NaY zeolite for separation of ethylene glycol and 1,2-butanediol: Experiment and molecular modelling 被引量:4
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作者 Pei Xiong Peng He +6 位作者 Yixin Qu liguo wang Yan Cao Shuang Xu Jiaqiang Chen Muhammad Ammar Huiquan Li 《Green Energy & Environment》 SCIE CSCD 2021年第1期102-113,共12页
The separation of ethylene glycol(EG)and 1,2-butanediol(1,2-BDO)azeotrope in the synthesis process of EG via coal and biomass is becoming of increasing commercial and environmental importance.Selective adsorption is d... The separation of ethylene glycol(EG)and 1,2-butanediol(1,2-BDO)azeotrope in the synthesis process of EG via coal and biomass is becoming of increasing commercial and environmental importance.Selective adsorption is deemed as the most promising methods because of energy saving and environment favorable.In this paper,NaY zeolite was used to separate 1,2-BDO from EG,and its adsorption properties was then investigated.The isotherms of EG and 1,2-BDO in vapor and liquid phases from 298 to 328 K indicated that they fitted Langmuir model quite well,and the NaY zeolite absorbent favored EG more than 1,2-BDO.The Grand Canonical Monte Carlo(GCMC)and molecular dynamics(MD)simulation techniques were conducted to investigate the competition adsorption and diffusion characteristics in different adsorption regions.It was observed that EG and 1,2-BDO molecules all have the most probable locations of the center of the 12-membered ring near the Na cations.The diffusivities of EG are lower than those of 1,2-BDO at the same adsorption concentration.At last,the breakthrough curves of the binary mixture regressed from the empirical Dose–Response model in fixed-bed column showed that the adsorption selectivity of EG could reach to as high as 2.43,verified that the NaY zeolite could effectively separate EG from 1,2-BDO.This work is also helpful for further separation of other dihydric alcohol mixtures from coal and biomass fermentation. 展开更多
关键词 Adsorption mechanism Ethylene glycol(EG) 1 2-Butanediol(1 2-BDO) NaY zeolite Fixed-bed column tests
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An efficient green route for hexamethylene-1,6-diisocyanate synthesis by thermal decomposition of hexamethylene-1,6-dicarbamate over Co3O4/ZSM-5 catalyst: An indirect utilization of CO2 被引量:4
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作者 Muhammad Ammar Yan Cao +3 位作者 Peng He liguo wang Jiaqiang Chen Huiquan Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第12期1760-1770,共11页
The utilization of CO2 as raw material for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate (HDC) is a promising approach for i... The utilization of CO2 as raw material for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate (HDC) is a promising approach for indirect utilization of CO2 to produce hexamethylene-1,6-diisocyanate (HDI). In this work, a green route was developed for the synthesis of HD1 by thermal decomposition of HDC over Co3O4/ZSM-5 catalyst, using chlorobenzene as low boiling point solvent. Different metal oxide supported catalysts were prepared by incipient wetness impregnation (IWI), PEG-additive (PEG) and deposition precipitation with ammonia evaporation (DP) methods. Their catalytic performances for the thermal decomposition of HDC were tested. The catalyst screening results showed that Co3O4/ZSM-525 catalysts prepared by different methods showed different performances in the order of Co3O4/ZSM-5 25(PEG) 〉 Co3O4/ZSM-525(IWI) 〉 Co3O4/ZSM-525(DP). The physicochemical properties of Co3O4/ZSM- 52s catalyst were characterized by XRD, FTIR, N2 adsorption-desorption measurements, NH3-TPD and XPS. The superior catalytic performance of Co3O4/ZSM-52S(PEG) catalyst was attributed to its relative surface content of Co3 +, surface lattice oxygen content and total acidity. Under the optimized reaction conditions: 6.5% HDC concentration in chlorobenzene, 1 wt% Co3O4/ZSM-525(PEG) catalyst, 250℃ temperature, 2.5 h time, 800 ml.min 1 nitrogen flow rate and 1.0 MPa pressure, the HDC conversion and HDI yield could reach 100% and 92.8% respectively. The Co3O4/ZSM-525(PEG) catalyst could be facilely separated from the reaction mixture, and reused without degradation in catalytic performance. Furthermore, a possible reaction mechanism was proposed based on the physicochemical properties of the Co3O4/ZSM-5 25 catalysts. 展开更多
关键词 Hexamethylene-1 6-dicarbamate (HDC)Hexamethylene-1 6-diisocyanate (HDI) Thermal decomposition Co3O4/ZSM-5 Heterogeneous catalyst
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Green and selective hydrogenation of aromatic diamines over the nanosheet Ru/g-C_(3)N_(4)-H_(2) catalyst prepared by ultrasonic assisted impregnation-deposition method 被引量:3
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作者 Huanhuan Yang liguo wang +5 位作者 Shuang Xu Yan Cao Peng He Jiaqiang Chen Zheng Zheng Huiquan Li 《Green Energy & Environment》 SCIE EI CSCD 2022年第6期1361-1376,共16页
In this study,nanosheet g-C_(3)N_(4)-H_(2) was prepared by thermal exfoliation of bulk g-C_(3)N_(4) under hydrogen.A series of Ru/g-C_(3)N_(4)-H_(2) catalysts with Ru species supported on the nanosheet g-C_(3)N_(4)-H_... In this study,nanosheet g-C_(3)N_(4)-H_(2) was prepared by thermal exfoliation of bulk g-C_(3)N_(4) under hydrogen.A series of Ru/g-C_(3)N_(4)-H_(2) catalysts with Ru species supported on the nanosheet g-C_(3)N_(4)-H_(2) were synthesized via ultrasonic assisted impregnation-deposition method.Ultrafine Ru nanoparticles(<2 nm)were highly dispersed on nanosheet g-C_(3)N_(4)-H_(2).Strong interaction due to Ru-Nx coordination facilitated the uniform distribution of Ru species.Meanwhile,the involvement of surface basicity derived from abundant nitrogen sites was favourable for enhancing the selective hydrogenation performance of bi-benzene ring,i.e.,almost complete 4,40-diaminodiphenylmethane(MDA)conversion and>99%4,40-diaminodicyclohexylmethane selectivity,corresponding to a reaction activity of 35.7 mol_(MDA) mol_(Ru)^(-1) h^(-1).Moreover,the reaction activity of catalyst in the fifth run was 36.5 mol_(MDA) mol_(Ru)^(-1) h^(-1),which was comparable with that of the fresh one.The computational results showed that g-C_(3)N_(4) as support was favorable for adsorption and dissociation of H_(2) molecules.Moreover,the substrate scope can be successfully expanded to a variety of other aromatic diamines.Therefore,this work provides an efficient and green catalyst system for selective hydrogenation of aromatic diamines. 展开更多
关键词 Nanosheet carbon nitride Ultrafine Ru species Selective hydrogenation Aromatic diamine Alicyclic diamine
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Effect of rare earth and Mn elements on the corrosion behavior of extruded AZ61 system in 3.5 wt%NaCl solution and salt spray test 被引量:3
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作者 Shijie Zhu Zhidan Liu +3 位作者 RuiXiao Qu liguo wang Qingkui Li Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS 2013年第3期249-255,共7页
In this study,multiple addition of rare earth(RE)and manganese(Mn)to AZ61 was conducted aiming to find out the influence to corrosion resistance.AZ61 containing different amounts of RE and Mn was investigated by elect... In this study,multiple addition of rare earth(RE)and manganese(Mn)to AZ61 was conducted aiming to find out the influence to corrosion resistance.AZ61 containing different amounts of RE and Mn was investigated by electrochemical measurement in condition of 3.5 wt%NaCl solution at 25°C.Gravimetric measurement was conducted in 5 wt%salt spray at 35°C and 3.5 wt%NaCl solution at 25°C.Samples were characterized by SEM,EDS,OM and XRD.The result shows that with RE addition Al8Mn5 in AZ61 changed into Al10RE2Mn7.The quantity ofβphase is reduced significantly.The multiple addition of RE and Mn improved the corrosion resistance of AZ61.When the ratio of Mn and RE is 0.3,alloy has the best property of corrosion resistance.In addition,the composite addition removed the impurity elements in AZ61 especially Fe. 展开更多
关键词 AZ61 Rare earth Multiple addition Corrosion resistance Electrochemical properties
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Integration of spatial attractions between and within pixels for sub-pixel mapping 被引量:3
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作者 Qunming wang liguo wang Danfeng Liu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第2期293-303,共11页
As a promising technique to enhance the spatial reso- lution of remote sensing imagery, sub-pixel mapping is processed based on the spatial dependence theory with the assumption that the land cover is spatially depend... As a promising technique to enhance the spatial reso- lution of remote sensing imagery, sub-pixel mapping is processed based on the spatial dependence theory with the assumption that the land cover is spatially dependent both within pixels and be- tween them. The spatial attraction is used as a tool to describe the dependence. First, the spatial attractions between pixels, sub- pixel/pixel spatial attraction model (SPSAM), are described by the modified SPSAM (MSPSAM) that estimates the attractions accord- ing to the distribution of sub-pixels within neighboring pixels. Then a mixed spatial attraction model (MSAM) for sub-pixel mapping is proposed that integrates the spatial attractions both within pix- els and between them. According to the expression of the MSAM maximumising the spatial attraction, the genetic algorithm is em- ployed to search the optimum solution and generate the sub-pixel mapping results. Experiments show that compared with SPSAM, MSPSAM and pixel swapping algorithm modified by initialization from SPSAM (MPS), MSAM can provide higher accuracy and more rational sub-pixel mapping results. 展开更多
关键词 remote sensing imagery sub-pixel mapping mixed spatial attraction model (MSAM) genetic algorithm (GA).
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Corrosion fatigue of the extruded Mg-Zn-Y-Nd alloy in simulated body fluid 被引量:4
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作者 Mengyao Liu Jianfeng wang +4 位作者 Shijie Zhu Yabo Zhang Yufeng Sun liguo wang Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE 2020年第1期231-240,共10页
Magnesium alloys were considered to be used as biodegradable implants due to their biocompatibility,biodegradability and nontoxicity.However,under the simultaneous action of corrosive environment and mechanical loadin... Magnesium alloys were considered to be used as biodegradable implants due to their biocompatibility,biodegradability and nontoxicity.However,under the simultaneous action of corrosive environment and mechanical loading in human body,magnesium alloys are easy to be affected by corrosion fatigue and stress corrosion cracking.In this work,the fatigue behavior of the extruded Mg-Zn-Y-Nd alloy used for vascular stents was studied both in air and in simulated body fluid(SBF).It was revealed that the fatigue limit of as-extruded Mg-Zn-Y-Nd alloy in air is about 65 MPa at 10^7 cycles,while there is no limit in SBF and shows a linear relationship between the fatigue life and stress amplitudes.The fatigue crack source in air was formed by the inclusions and defects.However,the stress corrosion and hydrogen embrittlement are the main reasons for the formation of the fatigue initial crack source in SBF. 展开更多
关键词 Biodegradable magnesium alloy Corrosion fatigue Simulated body fluid Fatigue crack source
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Microstructure and texture evolution of fine-grained Mg-Zn-Y-Nd alloy micro-tubes for biodegradable vascular stents processed by hot extrusion and rapid cooling 被引量:3
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作者 Kaikai Guo Mengyao Liu +5 位作者 Jianfeng wang Yufeng Sun Weiqing Li Shijie Zhu liguo wang Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS 2020年第3期873-882,共10页
Magnesium alloys have narrow available slip result from close-packed hexagonal structure that limit their processing properties.In the recent work,the Mg-2Zn-0.46Y-0.5Nd,as materials for degradable stents,was applied ... Magnesium alloys have narrow available slip result from close-packed hexagonal structure that limit their processing properties.In the recent work,the Mg-2Zn-0.46Y-0.5Nd,as materials for degradable stents,was applied to produce as-extruded micro-tube with an outer diameter of 3.0mm and a wall thickness of 0.35mm by hot extrusion with an extrusion ratio of 105:1 at 653K and rapid cooling.The fine microstructure of the dynamic recrystallization of as-extruded micro-tube could be preserved by rapid cooling such as water-cooled,resulting in more excellent mechanical properties relative to air-cooled micro-tube.The addition of rare earth elements Y and Nd results in continuous dynamic recrystallization dominated the dynamic recrystallization mechanism.During the hot extrusion process,the activation of the non-basal slip system,especially the pyramidal(c+a)slip,could significantly weaken the texture strength,and the as-extruded micro-tube exhibits weak"RE"texture components(011^(-)1)||ED and(1^(-)21^(-)1)||ED.Hence,the magnesium alloy micro-tube prepared by the rapid cooling has fine microstructure and weak texture,which is favorable for further process and governance. 展开更多
关键词 Magnesium alloy MICRO-TUBE Microstructure Rapid cooling Texture
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Non-phosgene synthesis of hexamethylene-1,6-diisocyanate from thermal decomposition of hexamethylene-1,6-dicarbamate over Zn–Co bimetallic supported ZSM-5 catalyst 被引量:2
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作者 Yan Cao Yafang Chi +3 位作者 Ammar Muhammad Peng He liguo wang Huiquan Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2019年第3期549-555,共7页
A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate(HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate(HDC) over Zn–Co bi-metallic supported ZSM-5 catalyst.The cataly... A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate(HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate(HDC) over Zn–Co bi-metallic supported ZSM-5 catalyst.The catalyst was characterized by FTIR and XRD analyses. Three solvents dioctyl sebacate(DOS), dibutyl sebacate(DBS) and 1-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_4) were investigated and compared; DOS gave better performance. The catalytic performances for thermal decomposition of HDC to HDI using DOS as solvent were then investigated, and the results showed that, under the optimized reaction conditions, i.e.,10 wt%concentration of HDC in DOS, 250 °C temperature, 60 min reaction time, 83.8% yield of HDI had been achieved over Zn–Co/ZSM-5. Decomposition of the intermediate hexamethylene-1-carbamate-6-isocyanate(HMI) over Zn–Co/ZSM-5 in DOS solvent was further studied and the results indicated that yield of HDI from HMI reached to 69.6%(98.6% HDI selectively) at 270 °C, which further increased the yield of the total HDI(HDI_(tol)) to as high as 95.0%. Recycling of catalyst showed that HDI and HMI yield slightly decreased, and by-product yield increased after the catalyst was reused for 4 times. At last possible reaction mechanism was proposed. 展开更多
关键词 NON-PHOSGENE Thermal decomposition Hexamethylene-1 6-diisocyanate Hexamethylene-1 6-dicarbamate BIMETALLIC SUPPORTED ZSM-5 catalyst
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A two-step superplastic forging forming of semi-continuously cast AZ70 magnesium alloy 被引量:2
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作者 Pan wang Shijie Zhu +2 位作者 liguo wang Lihong Wu Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS 2015年第1期70-75,共6页
A two-step technology combined forging with superplastic forming has been developed to enhance the forgeability of semi-continuously cast AZ70 magnesium alloy and realize the application of the as-cast magnesium alloy... A two-step technology combined forging with superplastic forming has been developed to enhance the forgeability of semi-continuously cast AZ70 magnesium alloy and realize the application of the as-cast magnesium alloy in large deformation bullet shell.In the first step,fine-grained microstructure preforms that are suitable for superplastic forming were obtained by reasonably designing the size of the initial blanks with the specific height-to-diameter ratio,upsetting the blanks and subsequent annealing.In the second step,the heat treated preforms were forged into the end products at the superplastic conditions.The end products exhibit high quality surface and satisfied microstructure.Consequently,this forming technology that not only avoids complicating the material preparation but also utilizes higher strain rate superplastic provides a near net-shaped novel method on magnesium forging forming technology using as-cast billet. 展开更多
关键词 Magnesium alloy SUPERPLASTICITY Recrystallization Casting Light microscopy Forging technology
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Local perceptions of the conversion of cropland to forestland program in Jiangxi, Shaanxi, and Sichuan, China 被引量:1
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作者 Guangyu wang Oliver Z.Ma +7 位作者 liguo wang Anil Shrestha Baozhang Chen Feng Mi Shirong Liu Xiaomin Guo Sarah Eshpeter John L.Innes 《Journal of Forestry Research》 SCIE CAS CSCD 2019年第5期1833-1847,共15页
Numerous land-use policies have been implemented in China in recent decades for ecological restoration and conservation to reduce environmental disasters and promote environmental sustainability.Many of these policies... Numerous land-use policies have been implemented in China in recent decades for ecological restoration and conservation to reduce environmental disasters and promote environmental sustainability.Many of these policies follow a top-down approach to implementation and as such,emphasize the hierarchical control within government structures.An understanding of local perceptions of land-use policies is important if the disconnect between policy makers and the target population is to be reduced and if program support is to improve.This study aimed to help improve local implementation,attitude toward,and engagement by examining the influence of socio-economic characteristics on the target population’s(local farmers)perception of the conversion of cropland to forestland program(CFPP)land use policy in Jiangxi,Sichuan,and Shaanxi provinces.It uses logistical regression models,with robust aspects of perception including confidence,support,transparency,prospects,fairness,and willingness to participate.Results indicate that social aspects as well as economic aspects are most important in influencing farmers’perceptions towards the CFPP.The farmers who have received technical support,rural male habitants,educated,and non-middle-aged farmers exhibit more positive perceptions of the program and are much more likely to support it,whereas farmers without any technical support or formal education,and female and middle-aged farmers are less likely to support the program.Importantly,this study also reveals the differences in responses,experiences and perceptions of the farmers living across different provinces.These empirical results provide insight into the influence of socio-economic characteristics on the perception of farmers towards land-use policies,which has important implications for designing targeted policy instruments and increasing farmer support for these policies.This knowledge can be harnessed and further evaluated in future research to improve citizen engagement,support,and understanding in order to help ecological restoration and conservation objectives be more effectively achieved. 展开更多
关键词 Forest policy ECOLOGICAL restoration LOCAL perception Social sustainability Land-use and change China
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In vitro corrosion properties of HTHEed Mg-Zn-Y-Nd alloy microtubes for stent applications:Influence of second phase particles and crystal orientation 被引量:1
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作者 Peihua Du Di Mei +4 位作者 Tsuyoshi Furushima Shijie Zhu liguo wang Yifan Zhou Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2022年第5期1286-1295,共10页
Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer... Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion,which is limiting their widespread application.To solve the problem of uneven degradation of stents,a HTHE(long-time and high-temperature heat treatment,large-reduction-ratio hot extrusion)process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this study.The heat treatment is to dissolve alloying elements and reduce the size of SPPs,and the hot extrusion is to acquire fine-grained and strongly textured microtubes.The microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of microtubes.After hot extrusion,microtubes show strong texture with basal plain oriented parallel to the longitudinal section(LS).The corrosion testing indicates that severe localized corrosion occurs on the cross section(CS)while localized corrosion is alleviated on the LS.Based on the different corrosion properties of the LS and CS,HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents. 展开更多
关键词 Mg-Zn-Y-Nd alloy MICROTUBES Heat treatment Hot extrusion Corrosion properties Cardiovascular stent
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Preparation of functional coating on magnesium alloy with hydrophilic polymers and bioactive peptides for improved corrosion resistance and biocompatibility 被引量:1
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作者 Lingchuang Bai Yahui wang +5 位作者 Lan Chen Jun wang Jingan Li Shijie Zhu liguo wang Shaokang Guan 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2022年第7期1957-1971,共15页
Biodegradable magnesium alloy stents(MAS)have great potential in the treatment of cardiovascular diseases.However,too fast degradation and the poor biocompatibility are still two key problems for the clinical utility ... Biodegradable magnesium alloy stents(MAS)have great potential in the treatment of cardiovascular diseases.However,too fast degradation and the poor biocompatibility are still two key problems for the clinical utility of MAS.In the present work,a functional coating composed of hydrophilic polymers and bioactive peptides was constructed on magnesium alloy to improve its corrosion resistance and biocompatibility in vitro and in vivo.Mg-Zn-Y-Nd(ZE21B)alloy modified with the functional coating exhibited moderate surface hydrophilicity and enhanced corrosion resistance.The favourable hemocompatibility of ZE21B alloy with the functional coating was confirmed by the in vitro blood experiments.Moreover,the modified ZE21B alloy could selectively promote the adhesion,proliferation,and migration of endothelial cells(ECs),but suppress these behaviors of smooth muscle cells(SMCs).Furthermore,the modified ZE21B alloy wires could alleviate intimal hyperplasia,enhance corrosion resistance and re-endothelialization in vivo transplantation experiment.These results collectively demonstrated that the functional coating improved the corrosion resistance and biocompatibility of ZE21B alloy.This functional coating provides new insight into the design and development of novel biodegradable stents for biomedical engineering. 展开更多
关键词 Magnesium alloy stent Functional coating Corrosion resistance BIOCOMPATIBILITY Hemocompatibility ENDOTHELIALIZATION
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