The effects of Manganese （Mn） incorporation on a precipitated iron-based Fischer-Tropsch synthesis （FTS） catalyst were investigated using N2 physical adsorption, air differential thermal analysis （DTA）, H2 tempe...The effects of Manganese （Mn） incorporation on a precipitated iron-based Fischer-Tropsch synthesis （FTS） catalyst were investigated using N2 physical adsorption, air differential thermal analysis （DTA）, H2 temperature-programmed reduction （TPR）, and Mǒssbauer spectroscopy. The FTS performances of the catalysts were tested in a slurry phase reactor. The characterization results indicated that Mn increased the surface area of the catalyst, and improved the dispersion of （α-Fe2O3 and reduced its crystallite size as a result of the high dispersion effect of Mn and the Fe-Mn interaction. The Fe-Mn interaction also suppressed the reduction of （α-Fe2O3 to Fe3O4, stabilized the FeO phase, and （or） decreased the carburization degree of the catalysts in the H2 and syngas reduction processes. In addition, incorporated Mn decreased the initial catalyst activity, but improved the catalyst stability because Mn restrained the reoxidation of iron carbides to Fe3O4, and improved further carburization of the catalysts. Manganese suppressed the formation of CH4 and increased the selectivity to light olefins （C2-4^=）, but it had little effect on the selectivities to heavy （C5＋） hydrocarbons. All these results indicated that the strong Fe-Mn interaction suppressed the chemisorptive effect of the Mn as an electronic promoter, to some extent, in the precipitated iron-manganese catalyst system.展开更多
According to the characteristic and the requirement of multipath planning, a new multipath planning method is proposed based on network. This method includes two steps： the construction of network and multipath searc...According to the characteristic and the requirement of multipath planning, a new multipath planning method is proposed based on network. This method includes two steps： the construction of network and multipath searching. The construction of network proceeds in three phases： the skeleton extraction of the configuration space, the judgment of the cross points in the skeleton and how to link the cross points to form a network. Multipath searching makes use of the network and iterative penalty method （IPM） to plan multi-paths, and adjusts the planar paths to satisfy the requirement of maneuverability of unmanned aerial vehicle （UAV）. In addition, a new height planning method is proposed to deal with the height planning of 3D route. The proposed algorithm can find multiple paths automatically according to distribution of terrain and threat areas with high efficiency. The height planning can make 3D route following the terrain. The simulation experiment illustrates the feasibility of the proposed method.展开更多
Excessive emission of carbon dioxide(CO_(2))has posed an imminent threat to human's environment and global prosperity.To achieve a sustainable future,solid oxide electrolysis cell(SOEC),which can efficiently combin...Excessive emission of carbon dioxide(CO_(2))has posed an imminent threat to human's environment and global prosperity.To achieve a sustainable future,solid oxide electrolysis cell(SOEC),which can efficiently combine CO_(2)reduction reaction(CO_(2)RR)and renewable energy storage,has become increasingly attractive owing to its unique functionalities.Additionally,symmetrical SOEC(SSOEC)has been considered as one of the most versatile cell configurations due to its simplified process,high compatibility,and low cost.However,the electrode material requirements become very demanding since efficient catalytic-activities are required for both CO_(2)RR and oxygen evolution reaction(OER).Herein,we demonstrate a novel high-entropy perovskite type symmetrical electrode Pr_(0.5)Ba_(0.5)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Cu_(0.2)O_(3-δ)(HE-PBM)for SSOEC.B-site doping of transition metals such as Mn,Fe,Co,Ni,and Cu in HE-PBM anode has been found to strongly accelerate the OER in the anode.Moreover,the presence of in-situ formed Fe–Co–Ni–Cu quaternary alloy nanocatalysts from HE-PBM cathode under reducing atmosphere has resulted in superior catalytic-activity towards CO_(2)RR.The faster kinetics are also reflected by the significantly low polarization resistance of 0.289Ω⋅cm^(-2)and high electrolysis current density of 1.21 A⋅cm^(-2)for CO_(2)RR at 2.0 V and 800℃.The excellent electrochemical performance and stability demonstrate that the highentropy perovskite material is a promising electrode material in SSOEC for efficient and durable CO_(2)RR.展开更多
Carbon nitride(g-C_(3)N_(4))is an attractive photocatalyst but commonly suffers from high photogenerated electron-hole recombination rate,low specific surface area,and narrow visible-light response range.Herein,3D ord...Carbon nitride(g-C_(3)N_(4))is an attractive photocatalyst but commonly suffers from high photogenerated electron-hole recombination rate,low specific surface area,and narrow visible-light response range.Herein,3D ordered macroporous(3DOM)g-C_(3)N_(4)/CdS was constructed by a feasible and inexpensive synthesis strategy of using template and light-assisted methods to solve the above problems.The formed heterostructure with suitable morphology,band structure,and extended light absorption range is beneficial to promoting photocatalytic Hgeneration.3DOM g-C_(3)N_(4)/Cd S exhibits a high Hproduce rate of718.6μmol hg,which is 73.3 times higher than that of g-C_(3)N_(4)and 25.4 times higher than that of3DOM g-C_(3)N_(4).The 3DOM structure can effectively increase the path length of light of g-C_(3)N_(4),improve the light energy conversion efficiency,and shorten the carrier transport distance.CdS enhances visiblelight response and produces many surface sites.Constructing a stable and tight interface between 3DOM g-C_(3)N_(4)and Cd S can promote the migration of photogenerated electrons and holes and consequently the visible-light catalytic activity.This study offers an effective designing strategy for heterostructure photocatalysts to achieve high activity and stable solar H2production.展开更多
Stroke and heart attack,which could be led by a kind of cerebrovascular and cardiovascular disease named as atherosclerosis,would seriously cause human morbidity and mortality.It is important for the early stage diagn...Stroke and heart attack,which could be led by a kind of cerebrovascular and cardiovascular disease named as atherosclerosis,would seriously cause human morbidity and mortality.It is important for the early stage diagnosis and monitoring medical intervention of the atherosclerosis.Carotid stenosis is a classical atherosclerotic lesion with vessel wall narrowing down and accumulating plaques burden.The carotid artery of intima-media thickness(IMT)is a key indicator to the disease.With the development of computer assisted diagnosis technology,the imaging techniques,segmentation algorithms,measurement methods,and evaluation tools have made considerable progress.Ultrasound imaging,being real-time,economic,reliable,and safe,now seems to become a standard in vascular assessment methodology especially for the measurement of IMT.This review firstly attempts to discuss the clinical relevance of measurements in clinical practice at first,and then followed by the challenges that one has to face when approaching the segmentation of ultrasound images.Secondly,the commonly used methods for the IMT segmentation and measurement are presented.Thirdly,discussion and evaluation of different segmentation techniques are performed.An overview of summary and future perspectives is given finally.展开更多
Multi‐modal brain image registration has been widely applied to functional localisation,neurosurgery and computational anatomy.The existing registration methods based on the dense deformation fields involve too many ...Multi‐modal brain image registration has been widely applied to functional localisation,neurosurgery and computational anatomy.The existing registration methods based on the dense deformation fields involve too many parameters,which is not conducive to the exploration of correct spatial correspondence between the float and reference images.Meanwhile,the unidirectional registration may involve the deformation folding,which will result in the change of topology during registration.To address these issues,this work has presented an unsupervised image registration method using the free form deformation(FFD)and the symmetry constraint‐based generative adversarial networks(FSGAN).The FSGAN utilises the principle component analysis network‐based structural representations of the reference and float images as the inputs and uses the generator to learn the FFD model parameters,thereby producing two deformation fields.Meanwhile,the FSGAN uses two discriminators to decide whether the bilateral registration have been realised simultaneously.Besides,the symmetry constraint is utilised to construct the loss function,thereby avoiding the deformation folding.Experiments on BrainWeb,high grade gliomas,IXI and LPBA40 show that compared with state‐of‐the‐art methods,the FSGAN provides superior performance in terms of visual comparisons and such quantitative indexes as dice value,target registration error and computational efficiency.展开更多
The non-local means (NLM) denoising method replaces each pixel by the weighted average of pixels with the sur-rounding neighborhoods. In this paper we employ a cosine weighting function instead of the original exponen...The non-local means (NLM) denoising method replaces each pixel by the weighted average of pixels with the sur-rounding neighborhoods. In this paper we employ a cosine weighting function instead of the original exponential func-tion to improve the efficiency of the NLM denoising method. The cosine function outperforms in the high level noise more than low level noise. To increase the performance more in the low level noise we calculate the neighborhood si-milarity weights in a lower-dimensional subspace using singular value decomposition (SVD). Experimental compari-sons between the proposed modifications against the original NLM algorithm demonstrate its superior denoising per-formance in terms of peak signal to noise ratio (PSNR) and histogram, using various test images corrupted by additive white Gaussian noise (AWGN).展开更多
Achieving highly efficient syngas conversion to olefins on the Fe-based catalysts is promising,but remains a big challenge due to the twin coexistence of the Fischer–Tropsch to olefins(FTO)and water gas shift(WGS)rea...Achieving highly efficient syngas conversion to olefins on the Fe-based catalysts is promising,but remains a big challenge due to the twin coexistence of the Fischer–Tropsch to olefins(FTO)and water gas shift(WGS)reactions.Herein,we developed a strategy via regulating the microenvironment of Fe catalyst and controlling the diffusion behaviors of critical intermediates to successfully realize the syngas conversion to olefins with low CO_(2)emission.A Fe@C catalyst with Fe species encapsulated in porous carbon was fabricated and achieved high single-pass olefins yield(>30%)and low CO_(2)selectivity(around 20%)simultaneously,which has ranked the top among the ever-reported advanced oxide–zeolite,Co-based,and Fe-based catalysts.A series of experimental and theoretical results revealed that the unique microenvironment could enrich olefins and inhibit hydrogenation reaction,therefore favoring high value-added olefins formation.Moreover,due to the accelerated diffusion of H_(2)O molecules,the WGS side reaction was obviously inhibited even at high CO conversion.Our research presented a new catalyst design strategy to realize highly efficient and controllable catalysis in syngas conversion.展开更多
Stable and flexible metal nanoparticles(NPs)with regeneration ability are critical for long-term operation of solid oxide electrolysis cells(SOECs).Herein,a novel perovskite electrode with stoichiometric Pr_(0.4)Sr_(0...Stable and flexible metal nanoparticles(NPs)with regeneration ability are critical for long-term operation of solid oxide electrolysis cells(SOECs).Herein,a novel perovskite electrode with stoichiometric Pr_(0.4)Sr_(0.6)Co_(0.125)Fe_(0.75)Mo_(0.125)O_(3)−δ(PSFCM)is synthesized and studied,which undergoes multiple redox cycles to validate its structural stability and NPs reversibility.The Co-Fe alloy has exsolved from the parent bulk under reducing atmosphere,and is capable of reincorporation into the parent oxide after re-oxidation treatment.During the redox process,we successfully manipulate the size and population density of the exsolved NPs,and find that the average particle size significantly reduces but the population density increases correspondingly.The electrode polarization resistance of the symmetric cell remains stable for 450 h,and even activates after the redox cycling,which may be attributed to the higher quantity and larger specific surface area of the regenerated Co-Fe alloy NPs.Moreover,the electrochemical performance towards carbon dioxide reduction reaction(CO_(2)RR)is evaluated,and the CO_(2)electrolyzer consisting of CoFe@PSCFM-Ce_(0.8)Sm_(0.2)O_(1.9)(SDC)dual-phase electrode exhibits an excellent current density of 1.42 A·cm^(−2)at 1.6 V,which reaches 1.7 times higher than 0.83 A·cm^(−2)for the pristine PSCFM electrode.Overall,with this flexible and reversible high-performance SOEC cathode material,new options and perspectives are provided for the efficient and durable CO_(2)electrolysis.展开更多
基金Foundation item:the National Outstanding Young Scientists Foundation of China(20625620)the National Key Basic Research Program of China(973 Program,2007CB216401)+1 种基金the National Natural Science Foundation of China(20590360)the Natural Science Foundation of Shanxi Province(2006021014).
文摘The effects of Manganese （Mn） incorporation on a precipitated iron-based Fischer-Tropsch synthesis （FTS） catalyst were investigated using N2 physical adsorption, air differential thermal analysis （DTA）, H2 temperature-programmed reduction （TPR）, and Mǒssbauer spectroscopy. The FTS performances of the catalysts were tested in a slurry phase reactor. The characterization results indicated that Mn increased the surface area of the catalyst, and improved the dispersion of （α-Fe2O3 and reduced its crystallite size as a result of the high dispersion effect of Mn and the Fe-Mn interaction. The Fe-Mn interaction also suppressed the reduction of （α-Fe2O3 to Fe3O4, stabilized the FeO phase, and （or） decreased the carburization degree of the catalysts in the H2 and syngas reduction processes. In addition, incorporated Mn decreased the initial catalyst activity, but improved the catalyst stability because Mn restrained the reoxidation of iron carbides to Fe3O4, and improved further carburization of the catalysts. Manganese suppressed the formation of CH4 and increased the selectivity to light olefins （C2-4^=）, but it had little effect on the selectivities to heavy （C5＋） hydrocarbons. All these results indicated that the strong Fe-Mn interaction suppressed the chemisorptive effect of the Mn as an electronic promoter, to some extent, in the precipitated iron-manganese catalyst system.
基金supported by the National High Technology Research and Development Program of China(2007AA12Z166)
文摘According to the characteristic and the requirement of multipath planning, a new multipath planning method is proposed based on network. This method includes two steps： the construction of network and multipath searching. The construction of network proceeds in three phases： the skeleton extraction of the configuration space, the judgment of the cross points in the skeleton and how to link the cross points to form a network. Multipath searching makes use of the network and iterative penalty method （IPM） to plan multi-paths, and adjusts the planar paths to satisfy the requirement of maneuverability of unmanned aerial vehicle （UAV）. In addition, a new height planning method is proposed to deal with the height planning of 3D route. The proposed algorithm can find multiple paths automatically according to distribution of terrain and threat areas with high efficiency. The height planning can make 3D route following the terrain. The simulation experiment illustrates the feasibility of the proposed method.
基金supported by National Natural Science Foundation of China(U21A20317),the National Key Research and Development Program of China(2022YFA1504701)the Fundamental Research Funds for the Central University(2042022gf0002)the U.S.National Science Foundation(1832809)and the start-up research funds from Wuhan Institute of Technology(K202201).
文摘Excessive emission of carbon dioxide(CO_(2))has posed an imminent threat to human's environment and global prosperity.To achieve a sustainable future,solid oxide electrolysis cell(SOEC),which can efficiently combine CO_(2)reduction reaction(CO_(2)RR)and renewable energy storage,has become increasingly attractive owing to its unique functionalities.Additionally,symmetrical SOEC(SSOEC)has been considered as one of the most versatile cell configurations due to its simplified process,high compatibility,and low cost.However,the electrode material requirements become very demanding since efficient catalytic-activities are required for both CO_(2)RR and oxygen evolution reaction(OER).Herein,we demonstrate a novel high-entropy perovskite type symmetrical electrode Pr_(0.5)Ba_(0.5)Mn_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Cu_(0.2)O_(3-δ)(HE-PBM)for SSOEC.B-site doping of transition metals such as Mn,Fe,Co,Ni,and Cu in HE-PBM anode has been found to strongly accelerate the OER in the anode.Moreover,the presence of in-situ formed Fe–Co–Ni–Cu quaternary alloy nanocatalysts from HE-PBM cathode under reducing atmosphere has resulted in superior catalytic-activity towards CO_(2)RR.The faster kinetics are also reflected by the significantly low polarization resistance of 0.289Ω⋅cm^(-2)and high electrolysis current density of 1.21 A⋅cm^(-2)for CO_(2)RR at 2.0 V and 800℃.The excellent electrochemical performance and stability demonstrate that the highentropy perovskite material is a promising electrode material in SSOEC for efficient and durable CO_(2)RR.
基金financially supported by the National Natural Science Foundation of China(Nos.51862023,51662030 and 21868016)the Natural Science Foundation of Jiangxi Province(No.20212BAB204051)。
文摘Carbon nitride(g-C_(3)N_(4))is an attractive photocatalyst but commonly suffers from high photogenerated electron-hole recombination rate,low specific surface area,and narrow visible-light response range.Herein,3D ordered macroporous(3DOM)g-C_(3)N_(4)/CdS was constructed by a feasible and inexpensive synthesis strategy of using template and light-assisted methods to solve the above problems.The formed heterostructure with suitable morphology,band structure,and extended light absorption range is beneficial to promoting photocatalytic Hgeneration.3DOM g-C_(3)N_(4)/Cd S exhibits a high Hproduce rate of718.6μmol hg,which is 73.3 times higher than that of g-C_(3)N_(4)and 25.4 times higher than that of3DOM g-C_(3)N_(4).The 3DOM structure can effectively increase the path length of light of g-C_(3)N_(4),improve the light energy conversion efficiency,and shorten the carrier transport distance.CdS enhances visiblelight response and produces many surface sites.Constructing a stable and tight interface between 3DOM g-C_(3)N_(4)and Cd S can promote the migration of photogenerated electrons and holes and consequently the visible-light catalytic activity.This study offers an effective designing strategy for heterostructure photocatalysts to achieve high activity and stable solar H2production.
基金This work is supported by Projects of International Cooperation and Exchanges,National Natural Science Foundation of China(NSFC)(Grant No.:30911120497)the National 973 project Grant No.:2011CB933103.
文摘Stroke and heart attack,which could be led by a kind of cerebrovascular and cardiovascular disease named as atherosclerosis,would seriously cause human morbidity and mortality.It is important for the early stage diagnosis and monitoring medical intervention of the atherosclerosis.Carotid stenosis is a classical atherosclerotic lesion with vessel wall narrowing down and accumulating plaques burden.The carotid artery of intima-media thickness(IMT)is a key indicator to the disease.With the development of computer assisted diagnosis technology,the imaging techniques,segmentation algorithms,measurement methods,and evaluation tools have made considerable progress.Ultrasound imaging,being real-time,economic,reliable,and safe,now seems to become a standard in vascular assessment methodology especially for the measurement of IMT.This review firstly attempts to discuss the clinical relevance of measurements in clinical practice at first,and then followed by the challenges that one has to face when approaching the segmentation of ultrasound images.Secondly,the commonly used methods for the IMT segmentation and measurement are presented.Thirdly,discussion and evaluation of different segmentation techniques are performed.An overview of summary and future perspectives is given finally.
基金supported in part by the National Key Research and Development Program of China under Grant 2018Y FE0206900in part by the National Natural Science Foundation of China under Grant 61871440in part by the CAAIHuawei MindSpore Open Fund.We gratefully acknowledge the support of MindSpore for this research.
文摘Multi‐modal brain image registration has been widely applied to functional localisation,neurosurgery and computational anatomy.The existing registration methods based on the dense deformation fields involve too many parameters,which is not conducive to the exploration of correct spatial correspondence between the float and reference images.Meanwhile,the unidirectional registration may involve the deformation folding,which will result in the change of topology during registration.To address these issues,this work has presented an unsupervised image registration method using the free form deformation(FFD)and the symmetry constraint‐based generative adversarial networks(FSGAN).The FSGAN utilises the principle component analysis network‐based structural representations of the reference and float images as the inputs and uses the generator to learn the FFD model parameters,thereby producing two deformation fields.Meanwhile,the FSGAN uses two discriminators to decide whether the bilateral registration have been realised simultaneously.Besides,the symmetry constraint is utilised to construct the loss function,thereby avoiding the deformation folding.Experiments on BrainWeb,high grade gliomas,IXI and LPBA40 show that compared with state‐of‐the‐art methods,the FSGAN provides superior performance in terms of visual comparisons and such quantitative indexes as dice value,target registration error and computational efficiency.
文摘The non-local means (NLM) denoising method replaces each pixel by the weighted average of pixels with the sur-rounding neighborhoods. In this paper we employ a cosine weighting function instead of the original exponential func-tion to improve the efficiency of the NLM denoising method. The cosine function outperforms in the high level noise more than low level noise. To increase the performance more in the low level noise we calculate the neighborhood si-milarity weights in a lower-dimensional subspace using singular value decomposition (SVD). Experimental compari-sons between the proposed modifications against the original NLM algorithm demonstrate its superior denoising per-formance in terms of peak signal to noise ratio (PSNR) and histogram, using various test images corrupted by additive white Gaussian noise (AWGN).
基金supported by the National Key Research and Development Program of China(2022YFA1504700)the National Natural Science Foundation of China(22308266,U21A20317,and U22A20394)+1 种基金the Innovative Groups in Hubei Province(2022CFA017)the China Postdoctoral Science Foundation(2021M702521).
文摘Achieving highly efficient syngas conversion to olefins on the Fe-based catalysts is promising,but remains a big challenge due to the twin coexistence of the Fischer–Tropsch to olefins(FTO)and water gas shift(WGS)reactions.Herein,we developed a strategy via regulating the microenvironment of Fe catalyst and controlling the diffusion behaviors of critical intermediates to successfully realize the syngas conversion to olefins with low CO_(2)emission.A Fe@C catalyst with Fe species encapsulated in porous carbon was fabricated and achieved high single-pass olefins yield(>30%)and low CO_(2)selectivity(around 20%)simultaneously,which has ranked the top among the ever-reported advanced oxide–zeolite,Co-based,and Fe-based catalysts.A series of experimental and theoretical results revealed that the unique microenvironment could enrich olefins and inhibit hydrogenation reaction,therefore favoring high value-added olefins formation.Moreover,due to the accelerated diffusion of H_(2)O molecules,the WGS side reaction was obviously inhibited even at high CO conversion.Our research presented a new catalyst design strategy to realize highly efficient and controllable catalysis in syngas conversion.
基金supported by the National Natural Science Foundation of China(No.U21A20317)the National Key Research and Development Program of China(No.2022YFA1504701)+2 种基金the Fundamental Research Funds for the Central Universities(No.2042022gf0002)the start-up research funds from Wuhan Institute of Technology(No.K202201)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515010429).
文摘Stable and flexible metal nanoparticles(NPs)with regeneration ability are critical for long-term operation of solid oxide electrolysis cells(SOECs).Herein,a novel perovskite electrode with stoichiometric Pr_(0.4)Sr_(0.6)Co_(0.125)Fe_(0.75)Mo_(0.125)O_(3)−δ(PSFCM)is synthesized and studied,which undergoes multiple redox cycles to validate its structural stability and NPs reversibility.The Co-Fe alloy has exsolved from the parent bulk under reducing atmosphere,and is capable of reincorporation into the parent oxide after re-oxidation treatment.During the redox process,we successfully manipulate the size and population density of the exsolved NPs,and find that the average particle size significantly reduces but the population density increases correspondingly.The electrode polarization resistance of the symmetric cell remains stable for 450 h,and even activates after the redox cycling,which may be attributed to the higher quantity and larger specific surface area of the regenerated Co-Fe alloy NPs.Moreover,the electrochemical performance towards carbon dioxide reduction reaction(CO_(2)RR)is evaluated,and the CO_(2)electrolyzer consisting of CoFe@PSCFM-Ce_(0.8)Sm_(0.2)O_(1.9)(SDC)dual-phase electrode exhibits an excellent current density of 1.42 A·cm^(−2)at 1.6 V,which reaches 1.7 times higher than 0.83 A·cm^(−2)for the pristine PSCFM electrode.Overall,with this flexible and reversible high-performance SOEC cathode material,new options and perspectives are provided for the efficient and durable CO_(2)electrolysis.
