Each morning at Yangluo Port in Wuhan,Hubei Province,the all-electric cargo vessel Huahang Xinneng No.1 completes a battery swap in under 10 minutes before returning to service with nearly 8,000 kWh of power onboard。
To conduct marine surveys,multiple unmanned surface vessels(Multi-USV)with different capabilities perform collaborative mapping in multiple designated areas.This paper proposes a task allocation algorithm based on int...To conduct marine surveys,multiple unmanned surface vessels(Multi-USV)with different capabilities perform collaborative mapping in multiple designated areas.This paper proposes a task allocation algorithm based on integer linear programming(ILP)with flow balance constraints,ensuring the fair and efficient distribution of sub-areas among USVs and maintaining strong connectivity of assigned regions.In the established gridmap,a search-based path planning algorithm is performed on the sub-areas according to the allocation scheme.It uses the greedy algorithm and the A*algorithm to achieve complete coverage of the barrier-free area and obtain an efficient trajectory of each USV.The greedy algorithm enables fast local traversal of unvisited grids,while the A*algorithm ensures navigation to escape from deadlock areas and maintains global path continuity.The comparison of task allocation results proves that the task allocation algorithm based on ILP improves the mapping efficiency and task distribution fairness.The proposed allocation method and result analysis provide a certain reference for the practical application ofMulti-USV to perform survey tasks collaboratively.展开更多
Dear Editor,Underactuated autonomous surface vessels(ASVs)are increasingly attracting attention from researchers because of a wide range of applications[1].Consequently,path following,a typical functionality for ASVs,...Dear Editor,Underactuated autonomous surface vessels(ASVs)are increasingly attracting attention from researchers because of a wide range of applications[1].Consequently,path following,a typical functionality for ASVs,has become a research focus[2].Despite the abundant study results,some challenging issues are still worthy of exploration and resolution,two of which are addressed in this letter.The first one is related to the guidance law.Currently,common guidance methods in the ASV field include the line-of-sight(LOS)guidance[3]and vector field(VF)guidance[4].The response quality of LOS guidance is highly related to the lookahead distance;a constant lookahead distance may result in undesired phenomena such as the singularity problem and the reduction of trajectory smoothness of ASVs(see[5]).To this end,several works have proposed modified LOS guidance laws(see[6]).Although the above modifications,as pointed out by[7],the VF guidance exhibits smaller crosstrack errors and better performances than the LOS guidance.However,the existing VF guidance is only available for straight lines and orbits rather than curved paths,a considerable obstacle that limits its practical application(see[8],[9]).Thus,the VF guidance for curved path following deserves more in-depth study.展开更多
Cardiovascular disease(CVD)is a major global health challenge,which causes significant illness and death worldwide.These include a range of conditions that affect the heart and blood vessels,including coro-nary artery...Cardiovascular disease(CVD)is a major global health challenge,which causes significant illness and death worldwide.These include a range of conditions that affect the heart and blood vessels,including coro-nary artery disease,stroke,peripheral artery disease,and heart failure.Despite advances in medicine and healthcare delivery,CVD continues to have a serious impact on individuals,families,and the healthcare system.This review begins by delineating the merits and demerits of commonly employed synthetic and natural materials for artificial blood vessels.It delves into various techniques commonly employed in the fabrication of artificial blood vessels,encompassing advanced textile technologies,electrospinning,ther-mally induced phase separation,and 3D printing.The review critically analyzes the attributes of different preparation methodologies alongside the latest advancements in research.The review also outlines the requisite performance requirements for artificial blood vessels,which encompass robust mechanical prop-erties,appropriate porosity,exceptional compatibility,and antibacterial attributes.It provides a succinct overview of ongoing effort s in vascular functionalization,particularly emphasizing thrombus mitigation,promotion of endothelialization,and enhancement of nitric oxide production.The review finally encap-sulates the primary challenges confronting vascular grafts and prospective avenues for future research.展开更多
Objective:To study the application effect of bundle nursing strategy in the maintenance of difficult blood vessels for long-term hemodialysis patients.Methods:A prospective study was conducted on 40 long-term hemodial...Objective:To study the application effect of bundle nursing strategy in the maintenance of difficult blood vessels for long-term hemodialysis patients.Methods:A prospective study was conducted on 40 long-term hemodialysis patients admitted from January 2024 to January 2025.The patients were randomly divided into a control group(20 cases)and an observation group(20 cases)using computer random sampling.The control group received routine nursing for difficult blood vessels,while the observation group received a bundle nursing strategy for difficult blood vessels.The self-care ability,complication rate,and nursing satisfaction were compared between the two groups.Results:After nursing,the self-care ability score of the observation group was higher than that of the control group(P<0.05).The complication rate in the observation group was lower than that in the control group(P<0.05).The nursing satisfaction in the observation group was higher than that in the control group(P<0.05).Conclusion:The application of the bundle nursing strategy in the maintenance of difficult blood vessels for long-term hemodialysis patients is beneficial for improving self-care ability,reducing complications,and increasing patient satisfaction with nursing services.展开更多
Frequent flood disasters caused by climate change may lead to tremendous economic and human losses along inland waterways.Emergency response and rescue vessels(ERRVs)play an essential role in minimizing losses and pro...Frequent flood disasters caused by climate change may lead to tremendous economic and human losses along inland waterways.Emergency response and rescue vessels(ERRVs)play an essential role in minimizing losses and protecting lives and property.However,the path planning of ERRVs has mainly depended on expert experiences instead of rational decision making.This paper proposes an improved artificial potential field(APF)algorithm to optimize the shortest path for ERRVs in the rescue process.To verify the feasibility of the proposed model,eight tests were carried out in two water areas of the Yangtze River.The results showed that the improved APF algorithm was efficient with fewer iterations and that the response time of path planning was reduced to around eight seconds.The improved APF algorithm performed better in the ERRV’s goal achievement,compared with the traditional algorithm.The path planning method for ERRVs proposed in this paper has theoretical and practical value in flood relief.It can be applied in the emergency management of ERRVs to accelerate flood management efficiency and improve capacity to prevent,mitigate,and relieve flood disasters.展开更多
The mechanical properties,microstructure and second phase precipitation behavior of flange forgings for high-pressure hydrogen storage vessels at different tempering temperatures(620–700℃)were studied.The results sh...The mechanical properties,microstructure and second phase precipitation behavior of flange forgings for high-pressure hydrogen storage vessels at different tempering temperatures(620–700℃)were studied.The results showed that when tempered at 620–680°C,the main microstructure of the test steel was tempered sorbite,and the main microstructure of tempered steel changed to martensite at 700℃.At 700℃,the dislocation density increased and some retained austenite existed.With the tempering temperature increasing,the yield strength showed a decreasing trend,the formation of fresh martensite made the tensile strength first decrease and then increase slightly,the impact energy at−40℃increased first and then decreased,and the impact energy at 660℃had the maximum value.The precipitates of MC type were mainly(Mo,V,Ti)C.The test steel had excellent strength and toughness matching at 660℃tempering,the tensile strength at different cross section locations was above 750 MPa,the impact energy was above 200 J at−40℃,and the relative percentage reduction of area(ZH2/ZN2)was above 75%at hydrogen environment of 6.3 MPa.展开更多
Segmentation of the retinal vessels in the fundus is crucial for diagnosing ocular diseases.Retinal vessel images often suffer from category imbalance and large scale variations.This ultimately results in incomplete v...Segmentation of the retinal vessels in the fundus is crucial for diagnosing ocular diseases.Retinal vessel images often suffer from category imbalance and large scale variations.This ultimately results in incomplete vessel segmentation and poor continuity.In this study,we propose CT-MFENet to address the aforementioned issues.First,the use of context transformer(CT)allows for the integration of contextual feature information,which helps establish the connection between pixels and solve the problem of incomplete vessel continuity.Second,multi-scale dense residual networks are used instead of traditional CNN to address the issue of inadequate local feature extraction when the model encounters vessels at multiple scales.In the decoding stage,we introduce a local-global fusion module.It enhances the localization of vascular information and reduces the semantic gap between high-and low-level features.To address the class imbalance in retinal images,we propose a hybrid loss function that enhances the segmentation ability of the model for topological structures.We conducted experiments on the publicly available DRIVE,CHASEDB1,STARE,and IOSTAR datasets.The experimental results show that our CT-MFENet performs better than most existing methods,including the baseline U-Net.展开更多
Objective To investigate the effects of histamine receptor antagonists on vasoconstriction induced by electrical stimulation （ES） on posterior auricular nerve,and to explore the pre-and post-synaptic effects of symp...Objective To investigate the effects of histamine receptor antagonists on vasoconstriction induced by electrical stimulation （ES） on posterior auricular nerve,and to explore the pre-and post-synaptic effects of sympathetic histamine on the vasomotor responses of vascular smooth muscle in rabbit ear.Methods ES was applied to posterior auricular nerves of the whole rabbit ear at 10 Hz,20 Hz and 40 Hz,respectively.Besides,the whole ear was perfused with different histamine receptor antagonists under constant perfusion pressure,and the changes in the flow rate of perfusate were observed.Results The flow rate of venous outflow was decreased by ES at all the 3 frequencies.The ES-induced vasoconstriction at 20 Hz and 40 Hz could be partly inhibited by H1 receptor antagonist chlorpheniramine （P0.05） .After exhaustion of histamine in mast cells by pretreatment with specific mast cell degranulator compound 48/80,chlorpheniramine could still inhibit the ES-induced flow rate reduction.In contrast,H2 receptor antagonist cimetidine could enhance the 40-Hz ES-induced flow rate reduction （P 0.05） .Moreover,ES-induced vasoconstriction at the 3 frequencies could all be enhanced by H3 receptor antagonist thioperamide （P0.05） .Conclusion Stimulation on the auricular nerve may evoke histamine release from sympathetic nerves rather than from mast cells.Moreover,the functions of sympathetic histamine vary from pre-synaptic modulation to post-synaptic vasoconstriction or vasodilatation,via activation of different histamine receptors.展开更多
Background:Limited data are available for sirolimus-eluting stent(SES,Cypher)implantation in patients with coronary artery disease in small vessels.The clinical longtermoutcomes of SES in patients with coronary artery...Background:Limited data are available for sirolimus-eluting stent(SES,Cypher)implantation in patients with coronary artery disease in small vessels.The clinical longtermoutcomes of SES in patients with coronary artery disease after intracoronary stenting in small vessels has not been yet evaluated.展开更多
[Objective] The aim of this study was to provide the theoretical basis for variety identification of carambola and pomiculture.[Method] The molecular structure of vessels in stem secondary xylem from three carambola v...[Objective] The aim of this study was to provide the theoretical basis for variety identification of carambola and pomiculture.[Method] The molecular structure of vessels in stem secondary xylem from three carambola varieties of Malaysia 8,Misi and Malaysia B17 were studied by cell image analysis system and microphotography.[Result] The molecular structure of vessels in stem secondary xylem from carambola was as follows:the first type had tails in two ends,the second type had tail in one end,and the third type had no tails in two ends.The average length of vessel elements was from 328.88 to 366.09 μm,while its average width was from 44.61 to 52.43 μm.Most of the end wall was simple perforation plates,while the alternate-opposite pitting was the major forms of pitting.[Conclusion] Most characteristics of vessel elements from carambola were evolutionary characters of vessel elements in the process of phylogeny,but there were more primitive characters,for example,both two ends of vessel had tails or just one end had tail,and end wall was inclined.The molecular structure of vessel from carambola was in accordance with its ecological adaptability,and the growth characteristics of different varieties were also in accordance with the difference of molecular structure of vessel.展开更多
AIM: To investigate age-and gender-related differences in non-culprit versus culprit coronary vessels assessed with virtual histology intravascular ultrasound (VH-IVUS). METHODS: In 390 patients referred for coronary ...AIM: To investigate age-and gender-related differences in non-culprit versus culprit coronary vessels assessed with virtual histology intravascular ultrasound (VH-IVUS). METHODS: In 390 patients referred for coronary angiography to a single center (Luzerner Kantonsspital, Switzerland) between May 2007 and January 2011, 691 proximal vessel segments in left anterior descending, circumflex and/or right coronary arteries were imaged by VH-IVUS. Plaque burden and plaque composition(fibrous, fibro-fatty, necrotic core and dense calcium volumes) were analyzed in 3 age tertiles, according to gender and separated for vessels containing non-culprit or culprit lesions. To classify as vessel containing a culprit lesion, the patient had to present with an acute coronary syndrome, and the VH-IVUS had to be performed in a vessel segment containing the culprit lesion according to conventional coronary angiography. RESULTS: In non-culprit vessels the plaque burden increased significantly with aging (in men from 37% ± 12% in the lowest to 46% ± 10% in the highest age tertile, P < 0.001; in women from 30% ± 9% to 40% ± 11%, P < 0.001); men had higher plaque burden than women at any age (P < 0.001 for each of the 3 age tertiles). In culprit vessels of the lowest age tertile, plaque burden was significantly higher than that in non- culprit vessels (in men 48% ± 6%, P < 0.001 as compared to non-culprit vessels; in women 44% ± 18%, P = 0.004 as compared to non-culprit vessels). Plaque burden of culprit vessels did not significantly change during aging (plaque burden in men of the highest age tertile 51% ± 9%, P = 0.523 as compared to lowest age tertile; in women of the highest age tertile 49% ± 8%, P = 0.449 as compared to lowest age tertile). In men, plaque morphology of culprit vessels became increasingly rupture-prone during aging (increasing percentages of necrotic core and dense calcium), whereas plaque morphology in non-culprit vessels was less rupture-prone and remained constant during aging. In women, necrotic core in non-culprit vessels was very low at young age, but increased during aging resulting in a plaque morphology that was very similar to men. Plaque morphology in culprit vessels of young women and men was similar. CONCLUSION: This study provides evidence that age-and gender-related differences in plaque burden and plaque composition significantly depend on whether the vessel contained a non-culprit or culprit lesion.展开更多
Multi-layer pressure vessels are widely used in every field of high pressure technology.For the purpose of enhancing a vessels＇ load bearing capacity,a beneficial process like shrink-fit is usually employed.However,f...Multi-layer pressure vessels are widely used in every field of high pressure technology.For the purpose of enhancing a vessels＇ load bearing capacity,a beneficial process like shrink-fit is usually employed.However,few documents on optimum design for multi-layer shrink-fit vessels made of different strength materials can be found,available data are mainly on two-layer vessels.In this paper,an optimum design approach is developed for shrink-fit multi-layer vessels under ultrahigh pressure by using different materials.Maximum shear stress theory is applied as design criteria.The inner and outer radii of a multi-layer vessel,as well as the material of each layer,are assumed to be known.The optimization mathematical model is,thereby,built.Lagrange multipliers method is required to obtain the optimal design formula of wall ratio（ratio of outer to inner radii） of each layer,from which the optimum formulas of shrinkage pressure and radial interference are derived with the superposition principle employed.These formulas are applicable for the optimization design of all multi-layer vessels made of different materials,or same materials.The formulas of the limit working pressure and the contact pressure show that the optimum wall ratio of each layer and limit working pressure are only related to all selected material strength and unrelated to the position of the layer placement in the vessel.However,shrinkage pressure is related to the position of the layer placement in the vessel.Optimization design of an open ended shrink-fit three-layer vessel using different materials and comparisons proved that the optimized multi-layer vessels have outstanding characteristics of small radial interference and are easier for assembly.When the stress of each layer is distributed more evenly and appropriately,the load bearing capability and safety of vessels are enhanced.Therefore,this design is material-saving and cost-effective,and has prospect of engineering application.展开更多
Cold-stretched pressure vessels from austenitic stainless steels （ASS） are widely used for storage and transportation of liquefied gases, and have such advantages as thin wall and light weight. Fatigue is an importa...Cold-stretched pressure vessels from austenitic stainless steels （ASS） are widely used for storage and transportation of liquefied gases, and have such advantages as thin wall and light weight. Fatigue is an important concern in these pressure vessels, which are subjected to alternative loads. Even though several codes and standards have guidelines on these pressure vessels, there are no relevant design methods on fatigue failure. To understand the fatigue properties of ASS 1.4301 （equivalents include UNS $30400 and AISI 304） in solution-annealed （SA） and cold-stretched conditions （9% strain level） and the response of fatigue properties to cold stretching （CS）, low-cycle fatigue （LCF） tests were performed at room temperature, with total strain amplitudes ranging from ：~0.4% to ＂0.8%. Martensite transformations were measured during the tests. Comparisons on cyclic stress response, cyclic stress-strain behavior, and fatigue life were carried out between SA and CS materials. Results show that CS reduces the initial hardening stage, but prolongs the softening period in the cyclic stress response. Martensite transformation helps form a stable regime and subsequent secondary hardening. The stresses of monotonic and cyclic stress-strain curves are improved by CS, which leads to a lower plastic strain and a much higher elastic strain. The fatigue resistance of the CS material is better than that of the SA material, which is approximately 1 - 103 to 2 - 104 cycles. The S-N curve of the ASME standard for ASS is compared with the fatigue data and is justified to be suitable for the fatigue design of cold-stretched pressure vessels. However, considering the CS material has a better fatigue resistance, the S-N curve will be more conservative. The present study would be helpful in making full use of the advantages of CS to develop a new S-N curve for fatigue design of cold-stretched pressure vessels.展开更多
文摘Each morning at Yangluo Port in Wuhan,Hubei Province,the all-electric cargo vessel Huahang Xinneng No.1 completes a battery swap in under 10 minutes before returning to service with nearly 8,000 kWh of power onboard。
基金supported in part by the International Science and Technology Project of Guangzhou Development District under Grant 2023GH08the Science and Technology Development Fund,MSAR,under Grants 0029/2022/AGJ and 0029/2023/RIA1the Program of Guangdong under Grant 2023A0505020003.
文摘To conduct marine surveys,multiple unmanned surface vessels(Multi-USV)with different capabilities perform collaborative mapping in multiple designated areas.This paper proposes a task allocation algorithm based on integer linear programming(ILP)with flow balance constraints,ensuring the fair and efficient distribution of sub-areas among USVs and maintaining strong connectivity of assigned regions.In the established gridmap,a search-based path planning algorithm is performed on the sub-areas according to the allocation scheme.It uses the greedy algorithm and the A*algorithm to achieve complete coverage of the barrier-free area and obtain an efficient trajectory of each USV.The greedy algorithm enables fast local traversal of unvisited grids,while the A*algorithm ensures navigation to escape from deadlock areas and maintains global path continuity.The comparison of task allocation results proves that the task allocation algorithm based on ILP improves the mapping efficiency and task distribution fairness.The proposed allocation method and result analysis provide a certain reference for the practical application ofMulti-USV to perform survey tasks collaboratively.
基金supported by the National Natural Science Foundation of China(62473243,62421004)the Fundamental Research Funds for the Provincial Universities(3072024 GH0404)+1 种基金the Key Research and Development Projects in Hainan Province(ZDYF2024GXJS009)the“Spring Wild Goose”Plan Project of Heilongjiang Province(CYQN24071).
文摘Dear Editor,Underactuated autonomous surface vessels(ASVs)are increasingly attracting attention from researchers because of a wide range of applications[1].Consequently,path following,a typical functionality for ASVs,has become a research focus[2].Despite the abundant study results,some challenging issues are still worthy of exploration and resolution,two of which are addressed in this letter.The first one is related to the guidance law.Currently,common guidance methods in the ASV field include the line-of-sight(LOS)guidance[3]and vector field(VF)guidance[4].The response quality of LOS guidance is highly related to the lookahead distance;a constant lookahead distance may result in undesired phenomena such as the singularity problem and the reduction of trajectory smoothness of ASVs(see[5]).To this end,several works have proposed modified LOS guidance laws(see[6]).Although the above modifications,as pointed out by[7],the VF guidance exhibits smaller crosstrack errors and better performances than the LOS guidance.However,the existing VF guidance is only available for straight lines and orbits rather than curved paths,a considerable obstacle that limits its practical application(see[8],[9]).Thus,the VF guidance for curved path following deserves more in-depth study.
基金the National Natural Science Foundation of China(No.82374295)the National Key R&D Program of China(No.2021YFE0111100)+1 种基金the Science and Technol-ogy Partnership Program by the Ministry of Science and Technol-ogy of China(No.KY202201002)the Jiangsu Provincial De-partment of Science and Technology(No.BZ2022017).
文摘Cardiovascular disease(CVD)is a major global health challenge,which causes significant illness and death worldwide.These include a range of conditions that affect the heart and blood vessels,including coro-nary artery disease,stroke,peripheral artery disease,and heart failure.Despite advances in medicine and healthcare delivery,CVD continues to have a serious impact on individuals,families,and the healthcare system.This review begins by delineating the merits and demerits of commonly employed synthetic and natural materials for artificial blood vessels.It delves into various techniques commonly employed in the fabrication of artificial blood vessels,encompassing advanced textile technologies,electrospinning,ther-mally induced phase separation,and 3D printing.The review critically analyzes the attributes of different preparation methodologies alongside the latest advancements in research.The review also outlines the requisite performance requirements for artificial blood vessels,which encompass robust mechanical prop-erties,appropriate porosity,exceptional compatibility,and antibacterial attributes.It provides a succinct overview of ongoing effort s in vascular functionalization,particularly emphasizing thrombus mitigation,promotion of endothelialization,and enhancement of nitric oxide production.The review finally encap-sulates the primary challenges confronting vascular grafts and prospective avenues for future research.
文摘Objective:To study the application effect of bundle nursing strategy in the maintenance of difficult blood vessels for long-term hemodialysis patients.Methods:A prospective study was conducted on 40 long-term hemodialysis patients admitted from January 2024 to January 2025.The patients were randomly divided into a control group(20 cases)and an observation group(20 cases)using computer random sampling.The control group received routine nursing for difficult blood vessels,while the observation group received a bundle nursing strategy for difficult blood vessels.The self-care ability,complication rate,and nursing satisfaction were compared between the two groups.Results:After nursing,the self-care ability score of the observation group was higher than that of the control group(P<0.05).The complication rate in the observation group was lower than that in the control group(P<0.05).The nursing satisfaction in the observation group was higher than that in the control group(P<0.05).Conclusion:The application of the bundle nursing strategy in the maintenance of difficult blood vessels for long-term hemodialysis patients is beneficial for improving self-care ability,reducing complications,and increasing patient satisfaction with nursing services.
基金The National Natural Science Foundation of China(Grant No.72274052)the National Natural Science Foundation of China(Grant No.72174173).
文摘Frequent flood disasters caused by climate change may lead to tremendous economic and human losses along inland waterways.Emergency response and rescue vessels(ERRVs)play an essential role in minimizing losses and protecting lives and property.However,the path planning of ERRVs has mainly depended on expert experiences instead of rational decision making.This paper proposes an improved artificial potential field(APF)algorithm to optimize the shortest path for ERRVs in the rescue process.To verify the feasibility of the proposed model,eight tests were carried out in two water areas of the Yangtze River.The results showed that the improved APF algorithm was efficient with fewer iterations and that the response time of path planning was reduced to around eight seconds.The improved APF algorithm performed better in the ERRV’s goal achievement,compared with the traditional algorithm.The path planning method for ERRVs proposed in this paper has theoretical and practical value in flood relief.It can be applied in the emergency management of ERRVs to accelerate flood management efficiency and improve capacity to prevent,mitigate,and relieve flood disasters.
基金supported by the National Key research and Development Program of China(No.2022YFB4003001).
文摘The mechanical properties,microstructure and second phase precipitation behavior of flange forgings for high-pressure hydrogen storage vessels at different tempering temperatures(620–700℃)were studied.The results showed that when tempered at 620–680°C,the main microstructure of the test steel was tempered sorbite,and the main microstructure of tempered steel changed to martensite at 700℃.At 700℃,the dislocation density increased and some retained austenite existed.With the tempering temperature increasing,the yield strength showed a decreasing trend,the formation of fresh martensite made the tensile strength first decrease and then increase slightly,the impact energy at−40℃increased first and then decreased,and the impact energy at 660℃had the maximum value.The precipitates of MC type were mainly(Mo,V,Ti)C.The test steel had excellent strength and toughness matching at 660℃tempering,the tensile strength at different cross section locations was above 750 MPa,the impact energy was above 200 J at−40℃,and the relative percentage reduction of area(ZH2/ZN2)was above 75%at hydrogen environment of 6.3 MPa.
基金the National Natural Science Foundation of China(No.62266025)。
文摘Segmentation of the retinal vessels in the fundus is crucial for diagnosing ocular diseases.Retinal vessel images often suffer from category imbalance and large scale variations.This ultimately results in incomplete vessel segmentation and poor continuity.In this study,we propose CT-MFENet to address the aforementioned issues.First,the use of context transformer(CT)allows for the integration of contextual feature information,which helps establish the connection between pixels and solve the problem of incomplete vessel continuity.Second,multi-scale dense residual networks are used instead of traditional CNN to address the issue of inadequate local feature extraction when the model encounters vessels at multiple scales.In the decoding stage,we introduce a local-global fusion module.It enhances the localization of vascular information and reduces the semantic gap between high-and low-level features.To address the class imbalance in retinal images,we propose a hybrid loss function that enhances the segmentation ability of the model for topological structures.We conducted experiments on the publicly available DRIVE,CHASEDB1,STARE,and IOSTAR datasets.The experimental results show that our CT-MFENet performs better than most existing methods,including the baseline U-Net.
基金supported by the National Natural Science Foundation of China(No.30770669,30800310)
文摘Objective To investigate the effects of histamine receptor antagonists on vasoconstriction induced by electrical stimulation （ES） on posterior auricular nerve,and to explore the pre-and post-synaptic effects of sympathetic histamine on the vasomotor responses of vascular smooth muscle in rabbit ear.Methods ES was applied to posterior auricular nerves of the whole rabbit ear at 10 Hz,20 Hz and 40 Hz,respectively.Besides,the whole ear was perfused with different histamine receptor antagonists under constant perfusion pressure,and the changes in the flow rate of perfusate were observed.Results The flow rate of venous outflow was decreased by ES at all the 3 frequencies.The ES-induced vasoconstriction at 20 Hz and 40 Hz could be partly inhibited by H1 receptor antagonist chlorpheniramine （P0.05） .After exhaustion of histamine in mast cells by pretreatment with specific mast cell degranulator compound 48/80,chlorpheniramine could still inhibit the ES-induced flow rate reduction.In contrast,H2 receptor antagonist cimetidine could enhance the 40-Hz ES-induced flow rate reduction （P 0.05） .Moreover,ES-induced vasoconstriction at the 3 frequencies could all be enhanced by H3 receptor antagonist thioperamide （P0.05） .Conclusion Stimulation on the auricular nerve may evoke histamine release from sympathetic nerves rather than from mast cells.Moreover,the functions of sympathetic histamine vary from pre-synaptic modulation to post-synaptic vasoconstriction or vasodilatation,via activation of different histamine receptors.
文摘Background:Limited data are available for sirolimus-eluting stent(SES,Cypher)implantation in patients with coronary artery disease in small vessels.The clinical longtermoutcomes of SES in patients with coronary artery disease after intracoronary stenting in small vessels has not been yet evaluated.
基金Supported by Guangdong Natural Science Foundation(04300850)~~
文摘[Objective] The aim of this study was to provide the theoretical basis for variety identification of carambola and pomiculture.[Method] The molecular structure of vessels in stem secondary xylem from three carambola varieties of Malaysia 8,Misi and Malaysia B17 were studied by cell image analysis system and microphotography.[Result] The molecular structure of vessels in stem secondary xylem from carambola was as follows:the first type had tails in two ends,the second type had tail in one end,and the third type had no tails in two ends.The average length of vessel elements was from 328.88 to 366.09 μm,while its average width was from 44.61 to 52.43 μm.Most of the end wall was simple perforation plates,while the alternate-opposite pitting was the major forms of pitting.[Conclusion] Most characteristics of vessel elements from carambola were evolutionary characters of vessel elements in the process of phylogeny,but there were more primitive characters,for example,both two ends of vessel had tails or just one end had tail,and end wall was inclined.The molecular structure of vessel from carambola was in accordance with its ecological adaptability,and the growth characteristics of different varieties were also in accordance with the difference of molecular structure of vessel.
基金Supported by Swiss Heart Foundation, Bern, Switzerlandthe Swiss National Science Foundation, No. 310000-118468/1, Bern,Switzerlandthe Kamillo-Eisner Foundation, Hergiswil,Switzerland
文摘AIM: To investigate age-and gender-related differences in non-culprit versus culprit coronary vessels assessed with virtual histology intravascular ultrasound (VH-IVUS). METHODS: In 390 patients referred for coronary angiography to a single center (Luzerner Kantonsspital, Switzerland) between May 2007 and January 2011, 691 proximal vessel segments in left anterior descending, circumflex and/or right coronary arteries were imaged by VH-IVUS. Plaque burden and plaque composition(fibrous, fibro-fatty, necrotic core and dense calcium volumes) were analyzed in 3 age tertiles, according to gender and separated for vessels containing non-culprit or culprit lesions. To classify as vessel containing a culprit lesion, the patient had to present with an acute coronary syndrome, and the VH-IVUS had to be performed in a vessel segment containing the culprit lesion according to conventional coronary angiography. RESULTS: In non-culprit vessels the plaque burden increased significantly with aging (in men from 37% ± 12% in the lowest to 46% ± 10% in the highest age tertile, P < 0.001; in women from 30% ± 9% to 40% ± 11%, P < 0.001); men had higher plaque burden than women at any age (P < 0.001 for each of the 3 age tertiles). In culprit vessels of the lowest age tertile, plaque burden was significantly higher than that in non- culprit vessels (in men 48% ± 6%, P < 0.001 as compared to non-culprit vessels; in women 44% ± 18%, P = 0.004 as compared to non-culprit vessels). Plaque burden of culprit vessels did not significantly change during aging (plaque burden in men of the highest age tertile 51% ± 9%, P = 0.523 as compared to lowest age tertile; in women of the highest age tertile 49% ± 8%, P = 0.449 as compared to lowest age tertile). In men, plaque morphology of culprit vessels became increasingly rupture-prone during aging (increasing percentages of necrotic core and dense calcium), whereas plaque morphology in non-culprit vessels was less rupture-prone and remained constant during aging. In women, necrotic core in non-culprit vessels was very low at young age, but increased during aging resulting in a plaque morphology that was very similar to men. Plaque morphology in culprit vessels of young women and men was similar. CONCLUSION: This study provides evidence that age-and gender-related differences in plaque burden and plaque composition significantly depend on whether the vessel contained a non-culprit or culprit lesion.
基金supported by Key Scientific Research Project of Baoji University of Arts and Sciences of China (Grant No.ZK0727)Shanxi Provincial Special Foundation Project of Key Discipline Construction of China
文摘Multi-layer pressure vessels are widely used in every field of high pressure technology.For the purpose of enhancing a vessels＇ load bearing capacity,a beneficial process like shrink-fit is usually employed.However,few documents on optimum design for multi-layer shrink-fit vessels made of different strength materials can be found,available data are mainly on two-layer vessels.In this paper,an optimum design approach is developed for shrink-fit multi-layer vessels under ultrahigh pressure by using different materials.Maximum shear stress theory is applied as design criteria.The inner and outer radii of a multi-layer vessel,as well as the material of each layer,are assumed to be known.The optimization mathematical model is,thereby,built.Lagrange multipliers method is required to obtain the optimal design formula of wall ratio（ratio of outer to inner radii） of each layer,from which the optimum formulas of shrinkage pressure and radial interference are derived with the superposition principle employed.These formulas are applicable for the optimization design of all multi-layer vessels made of different materials,or same materials.The formulas of the limit working pressure and the contact pressure show that the optimum wall ratio of each layer and limit working pressure are only related to all selected material strength and unrelated to the position of the layer placement in the vessel.However,shrinkage pressure is related to the position of the layer placement in the vessel.Optimization design of an open ended shrink-fit three-layer vessel using different materials and comparisons proved that the optimized multi-layer vessels have outstanding characteristics of small radial interference and are easier for assembly.When the stress of each layer is distributed more evenly and appropriately,the load bearing capability and safety of vessels are enhanced.Therefore,this design is material-saving and cost-effective,and has prospect of engineering application.
基金Project supported by the National Key Technology R&D Program (No.2011BAK06B0205)the International Science and Technology Cooperation Project (No. 2010DFB42960)the Key Technology Innovation Team of Zhejiang Province (No. 2010R50001),China
文摘Cold-stretched pressure vessels from austenitic stainless steels （ASS） are widely used for storage and transportation of liquefied gases, and have such advantages as thin wall and light weight. Fatigue is an important concern in these pressure vessels, which are subjected to alternative loads. Even though several codes and standards have guidelines on these pressure vessels, there are no relevant design methods on fatigue failure. To understand the fatigue properties of ASS 1.4301 （equivalents include UNS $30400 and AISI 304） in solution-annealed （SA） and cold-stretched conditions （9% strain level） and the response of fatigue properties to cold stretching （CS）, low-cycle fatigue （LCF） tests were performed at room temperature, with total strain amplitudes ranging from ：~0.4% to ＂0.8%. Martensite transformations were measured during the tests. Comparisons on cyclic stress response, cyclic stress-strain behavior, and fatigue life were carried out between SA and CS materials. Results show that CS reduces the initial hardening stage, but prolongs the softening period in the cyclic stress response. Martensite transformation helps form a stable regime and subsequent secondary hardening. The stresses of monotonic and cyclic stress-strain curves are improved by CS, which leads to a lower plastic strain and a much higher elastic strain. The fatigue resistance of the CS material is better than that of the SA material, which is approximately 1 - 103 to 2 - 104 cycles. The S-N curve of the ASME standard for ASS is compared with the fatigue data and is justified to be suitable for the fatigue design of cold-stretched pressure vessels. However, considering the CS material has a better fatigue resistance, the S-N curve will be more conservative. The present study would be helpful in making full use of the advantages of CS to develop a new S-N curve for fatigue design of cold-stretched pressure vessels.
