Various land use and land cover(LULC)products have been produced over the past decade with the development of remote sensing technology.Despite the differences in LULC classification schemes,there is a lack of researc...Various land use and land cover(LULC)products have been produced over the past decade with the development of remote sensing technology.Despite the differences in LULC classification schemes,there is a lack of research on assessing the accuracy of their application to croplands in a unified framework.Thus,this study evaluated the spatial and area accuracies of cropland classification for four commonly used global LULC products(i.e.,MCD12Q1V6,GlobCover2009,FROM-GLC and GlobeLand30)based on the harmonised FAO criterion,and quantified the relationships between four factors(i.e.,slope,elevation,field size and crop system)and cropland classification agreement.The validation results indicated that MCD12Q1 and GlobeLand30 performed well in cropland classification regarding spatial consistency,with overall accuracies of 94.90 and 93.52%,respectively.The FROMGLC showed the worst performance,with an overall accuracy of 83.17%.Overlaying the cropland generated by the four global LULC products,we found the proportions of complete agreement and disagreement were 15.51 and 44.72% for the cropland classification,respectively.High consistency was mainly observed in the Northeast China Plain,the Huang-Huai-Hai Plain and the northern part of the Middle-lower Yangtze Plain,China.In contrast,low consistency was detected primarily on the eastern edge of the northern and semiarid region,the Yunnan-Guizhou Plateau and southern China.Field size was the most important factor for mapping cropland.For area accuracy,compared with China Statistical Yearbook data at the provincial scale,the accuracies of different products in descending order were:GlobeLand30,FROM-GLC,MCD12Q1,and GlobCover2009.The cropland classification schemes mainly caused large area deviations among the four products,and they also resulted in the different ranks of spatial accuracy and area accuracy among the four products.Our results can provide valuable suggestions for selecting cropland products at the national or provincial scale and help cropland mapping and reconstruction,which is essential for food security and crop management,so they can also contribute to achieving the Sustainable Development Goals issued by the United Nations.展开更多
According to clinical studies,upper limb robotic suits are vital to reduce therapist fatigue and accelerate patient rehabilitation.Soft pneumatic actuators have drawn increasing attention for the development of wearab...According to clinical studies,upper limb robotic suits are vital to reduce therapist fatigue and accelerate patient rehabilitation.Soft pneumatic actuators have drawn increasing attention for the development of wearable robots due to their low weight,flexibility,and high power-to-weight ratio.However,most of current actuators were designed for the flexion assistance of a specific joint,and that for joint extension requires further investigation.Furthermore,designing an actuator for diverse working scenarios remains a challenge.In this paper,we propose an all-fabric bi-directional actuator to assist the flexion and extension of the elbow,wrist,and fingers.A mathematical model is presented that predicts the deformation and guides the design of the proposed bi-directional actuator.To further validate the applicability and adaptability of the proposed actuator for different joints,we developed a 3-DOF soft robotic suit.Preliminary results show that the robotic suit can assist the motion of the elbow,wrist,and finger of the subject.展开更多
Thirty-four patients with cerebral infarction and 18 patients with transient ischemic attack were examined by multi-slice spiral CT scan, CT perfusion imaging, and CT angiography within 6 hours after onset. By CT perf...Thirty-four patients with cerebral infarction and 18 patients with transient ischemic attack were examined by multi-slice spiral CT scan, CT perfusion imaging, and CT angiography within 6 hours after onset. By CT perfusion imaging, 29 cases in the cerebral infarction group and 10 cases in the transient ischemic attack group presented with abnormal blood flow perfusion, which corresponded to the clinical symptoms. By CT angiography, various degrees of vascular stenosis could be detected in 41 patients, including 33 in the cerebral infarction group and eight in the transient ischemic attack group. The incidence of intracranial artery stenosis was higher than that of extracranial artery stenosis. The intracranial artery stenosis was located predominantly in the middle cerebral artery and carotid artery siphon, while the extracranial artery stenosis occurred mainly in the bifurcation of the common carotid artery and the opening of the vertebral artery. There were 34 cases (83%) with convict vascular stenosis and perfusion abnormalities, and five cases (45%) with perfusion abnormalities but without convict vascular stenosis. The incidence of cerebral infarction in patients with National Institutes of Health Stroke Scale scores ≥ 5 points during onset was significantly higher than that in patients with National Institutes of Health Stroke Scale scores < 5 points. These experimental findings indicate that the combined application of various CT imaging methods allows early diagnosis of acute ischemic cerebrovascular disease, which can comprehensively analyze the pathogenesis and severity of acute ischemic cerebrovascular disease at the morphological and functional levels.展开更多
OBJECTIVE:To identify global research trends in the application of MRI for monitoring stem cell transplantation using a bibliometric analysis of Web of Science.DATA RETRIEVAL:We performed a bibliometric analysis of st...OBJECTIVE:To identify global research trends in the application of MRI for monitoring stem cell transplantation using a bibliometric analysis of Web of Science.DATA RETRIEVAL:We performed a bibliometric analysis of studies relating to the application of MRI for detecting stem cell transplantation for the treatment of cerebral ischemia using papers in Web of Science published from 2002 to 2011.SELECTION CRITERIA:The inclusion criteria were:(a) peer-reviewed articles on the application of MRI for detecting transplanted stem cells published and indexed in Web of Science;(b) year of publication between 2002 and 2011.Exclusion criteria were:(a) articles that required manual searching or telephone access;(b) some corrected papers.MAIN OUTCOME MEASURES:(1) Annual publication output;(2) distribution according to journals;(3) distribution according to institution;(4) distribution according to country;(5) top cited authors over the last 10 years.RESULTS:A total of 1 498 studies related to the application of MRI for monitoring stem cell transplantation appeared in Web of Science from 2002 to 2011,almost half of which were derived from American authors and institutes.The number of studies on the application of MRI for detecting stem cell transplantation has gradually increased over the past 10 years.Most papers on this topic appeared in Magnetic Resonance in Medicine.CONCLUSION:This analysis suggests that few experimental studies have been investigated the use of MRI for tracking SPIO-labeled human umbilical cord blood-derived mesenchymal stem cells during the treatment of cerebral ischemia.展开更多
In situ tissue engineering is a powerful strategy for the treatment of bone defects.It could overcome the limitations of traditional bone tissue engineering,which typically involves extensive cell expansion steps,low ...In situ tissue engineering is a powerful strategy for the treatment of bone defects.It could overcome the limitations of traditional bone tissue engineering,which typically involves extensive cell expansion steps,low cell survival rates upon transplantation,and a risk of immuno-rejection.Here,a porous scaffold polycaprolactone(PCL)/decellularized small intestine submucosa(SIS)was fabricated via cryogenic free-form extrusion,followed by surface modification with aptamer and PlGF-2_(123-144)*-fused BMP2(pBMP2).The two bioactive molecules were delivered sequentially.The aptamer Apt19s,which exhibited binding affinity to bone marrow-derived mesenchymal stem cells(BMSCs),was quickly released,facilitating the mobilization and recruitment of host BMSCs.BMP2 fused with a PlGF-2_(123-144)peptide,which showed“super-affinity”to the ECM matrix,was released in a slow and sustained manner,inducing BMSC osteogenic differentiation.In vitro results showed that the sequential release of PCL/SIS-pBMP2-Apt19s promoted cell migration,proliferation,alkaline phosphatase activity,and mRNA expression of osteogenesis-related genes.The in vivo results demonstrated that the sequential release system of PCL/SIS-pBMP2-Apt19s evidently increased bone formation in rat calvarial critical-sized defects compared to the sequential release system of PCL/SIS-BMP2-Apt19s.Thus,the novel delivery system shows potential as an ideal alternative for achieving cell-free scaffold-based bone regeneration in situ.展开更多
A kind of interlaminar film with carbon nanotubes inserted into polyether ketone with cardo was used for lightning strike protection of composite laminates. The distribution of the interlaminar film was investigated b...A kind of interlaminar film with carbon nanotubes inserted into polyether ketone with cardo was used for lightning strike protection of composite laminates. The distribution of the interlaminar film was investigated by experimental and numerical methods. Artificial lightning strike tests were conducted for 12-film carbon nanotube and traditional surface silver coating protected specimens. Then corresponding finite element models(FEMs) were established to analyze the lightning strike effect and validated by the experimental results. Based on the FEMs, the number, distribution and thickness of interlaminar film were investigated in order to obtain equivalent protection effect with the traditional surface silver coating. The results show that only the first two layers were damaged for the surface silver coating protected specimen, while 5 layers were ablated for the 12-film protected specimen. Lightning strike damage area of the laminate protected with 5-film carbon nanotube is almost the same as that of the laminate protected with 12-film carbon nanotube. Compared with traditional surface silver coating protection, one film protection with thickness of 360 lm can make the laminate to obtain equivalent damage depth, 54.8% smaller damage area and 58% less additional weight. And reparability of the laminate is better than that of the laminate protected with 5 interlaminar films.展开更多
The residual stress is formed in YBa_(2)Cu_(3)O_(7-δ) (YBCO) bulk superconductors,which undergoes a complex fabrication process and experienced a huge temperature change about 1000℃.The residual stress may result in...The residual stress is formed in YBa_(2)Cu_(3)O_(7-δ) (YBCO) bulk superconductors,which undergoes a complex fabrication process and experienced a huge temperature change about 1000℃.The residual stress may result in micro-cracks in YBCO bulks and cause degradation of its superconducting and mechanical properties.It will be greatly helpful to reform the structural designs if the distribution of residual stress in YBCO bulk can be investigated.The traditional method of measuring residual stress does not apply to oxide ceramics as they are brittle materials.In this paper,a YBCO bulk was sliced into pieces of several millimeters in height,which could thus be treated as a plane-stress problem.The residual stress and principal stress angle for YBCO bulk have been obtained by an artificial hole-drilling method with very low speed.展开更多
基金supported by the National Key Research and Development Program of China(2022YFB3903503)the National Natural Science Foundation of China(U1901601)the Science and Technology Project of the Department of Education of Jiangxi Province,China(GJJ210541)。
文摘Various land use and land cover(LULC)products have been produced over the past decade with the development of remote sensing technology.Despite the differences in LULC classification schemes,there is a lack of research on assessing the accuracy of their application to croplands in a unified framework.Thus,this study evaluated the spatial and area accuracies of cropland classification for four commonly used global LULC products(i.e.,MCD12Q1V6,GlobCover2009,FROM-GLC and GlobeLand30)based on the harmonised FAO criterion,and quantified the relationships between four factors(i.e.,slope,elevation,field size and crop system)and cropland classification agreement.The validation results indicated that MCD12Q1 and GlobeLand30 performed well in cropland classification regarding spatial consistency,with overall accuracies of 94.90 and 93.52%,respectively.The FROMGLC showed the worst performance,with an overall accuracy of 83.17%.Overlaying the cropland generated by the four global LULC products,we found the proportions of complete agreement and disagreement were 15.51 and 44.72% for the cropland classification,respectively.High consistency was mainly observed in the Northeast China Plain,the Huang-Huai-Hai Plain and the northern part of the Middle-lower Yangtze Plain,China.In contrast,low consistency was detected primarily on the eastern edge of the northern and semiarid region,the Yunnan-Guizhou Plateau and southern China.Field size was the most important factor for mapping cropland.For area accuracy,compared with China Statistical Yearbook data at the provincial scale,the accuracies of different products in descending order were:GlobeLand30,FROM-GLC,MCD12Q1,and GlobCover2009.The cropland classification schemes mainly caused large area deviations among the four products,and they also resulted in the different ranks of spatial accuracy and area accuracy among the four products.Our results can provide valuable suggestions for selecting cropland products at the national or provincial scale and help cropland mapping and reconstruction,which is essential for food security and crop management,so they can also contribute to achieving the Sustainable Development Goals issued by the United Nations.
基金The research is supported by the National Natural Science Foundation of China(52275002)the Open Laboratory Concept Verification Project of Zhongguancun National Demonstration Zone(Grant No.202005226).
文摘According to clinical studies,upper limb robotic suits are vital to reduce therapist fatigue and accelerate patient rehabilitation.Soft pneumatic actuators have drawn increasing attention for the development of wearable robots due to their low weight,flexibility,and high power-to-weight ratio.However,most of current actuators were designed for the flexion assistance of a specific joint,and that for joint extension requires further investigation.Furthermore,designing an actuator for diverse working scenarios remains a challenge.In this paper,we propose an all-fabric bi-directional actuator to assist the flexion and extension of the elbow,wrist,and fingers.A mathematical model is presented that predicts the deformation and guides the design of the proposed bi-directional actuator.To further validate the applicability and adaptability of the proposed actuator for different joints,we developed a 3-DOF soft robotic suit.Preliminary results show that the robotic suit can assist the motion of the elbow,wrist,and finger of the subject.
基金supported by the Youth Fund of the First Clinical College of Liaoning Medical University, No. 2010C20
文摘Thirty-four patients with cerebral infarction and 18 patients with transient ischemic attack were examined by multi-slice spiral CT scan, CT perfusion imaging, and CT angiography within 6 hours after onset. By CT perfusion imaging, 29 cases in the cerebral infarction group and 10 cases in the transient ischemic attack group presented with abnormal blood flow perfusion, which corresponded to the clinical symptoms. By CT angiography, various degrees of vascular stenosis could be detected in 41 patients, including 33 in the cerebral infarction group and eight in the transient ischemic attack group. The incidence of intracranial artery stenosis was higher than that of extracranial artery stenosis. The intracranial artery stenosis was located predominantly in the middle cerebral artery and carotid artery siphon, while the extracranial artery stenosis occurred mainly in the bifurcation of the common carotid artery and the opening of the vertebral artery. There were 34 cases (83%) with convict vascular stenosis and perfusion abnormalities, and five cases (45%) with perfusion abnormalities but without convict vascular stenosis. The incidence of cerebral infarction in patients with National Institutes of Health Stroke Scale scores ≥ 5 points during onset was significantly higher than that in patients with National Institutes of Health Stroke Scale scores < 5 points. These experimental findings indicate that the combined application of various CT imaging methods allows early diagnosis of acute ischemic cerebrovascular disease, which can comprehensively analyze the pathogenesis and severity of acute ischemic cerebrovascular disease at the morphological and functional levels.
文摘OBJECTIVE:To identify global research trends in the application of MRI for monitoring stem cell transplantation using a bibliometric analysis of Web of Science.DATA RETRIEVAL:We performed a bibliometric analysis of studies relating to the application of MRI for detecting stem cell transplantation for the treatment of cerebral ischemia using papers in Web of Science published from 2002 to 2011.SELECTION CRITERIA:The inclusion criteria were:(a) peer-reviewed articles on the application of MRI for detecting transplanted stem cells published and indexed in Web of Science;(b) year of publication between 2002 and 2011.Exclusion criteria were:(a) articles that required manual searching or telephone access;(b) some corrected papers.MAIN OUTCOME MEASURES:(1) Annual publication output;(2) distribution according to journals;(3) distribution according to institution;(4) distribution according to country;(5) top cited authors over the last 10 years.RESULTS:A total of 1 498 studies related to the application of MRI for monitoring stem cell transplantation appeared in Web of Science from 2002 to 2011,almost half of which were derived from American authors and institutes.The number of studies on the application of MRI for detecting stem cell transplantation has gradually increased over the past 10 years.Most papers on this topic appeared in Magnetic Resonance in Medicine.CONCLUSION:This analysis suggests that few experimental studies have been investigated the use of MRI for tracking SPIO-labeled human umbilical cord blood-derived mesenchymal stem cells during the treatment of cerebral ischemia.
基金the National Natural Science Foundation of China(grant numbers 81902219,81672158 and 81873999)the National Key R&D Program of China(2016YFC1100100).
文摘In situ tissue engineering is a powerful strategy for the treatment of bone defects.It could overcome the limitations of traditional bone tissue engineering,which typically involves extensive cell expansion steps,low cell survival rates upon transplantation,and a risk of immuno-rejection.Here,a porous scaffold polycaprolactone(PCL)/decellularized small intestine submucosa(SIS)was fabricated via cryogenic free-form extrusion,followed by surface modification with aptamer and PlGF-2_(123-144)*-fused BMP2(pBMP2).The two bioactive molecules were delivered sequentially.The aptamer Apt19s,which exhibited binding affinity to bone marrow-derived mesenchymal stem cells(BMSCs),was quickly released,facilitating the mobilization and recruitment of host BMSCs.BMP2 fused with a PlGF-2_(123-144)peptide,which showed“super-affinity”to the ECM matrix,was released in a slow and sustained manner,inducing BMSC osteogenic differentiation.In vitro results showed that the sequential release of PCL/SIS-pBMP2-Apt19s promoted cell migration,proliferation,alkaline phosphatase activity,and mRNA expression of osteogenesis-related genes.The in vivo results demonstrated that the sequential release system of PCL/SIS-pBMP2-Apt19s evidently increased bone formation in rat calvarial critical-sized defects compared to the sequential release system of PCL/SIS-BMP2-Apt19s.Thus,the novel delivery system shows potential as an ideal alternative for achieving cell-free scaffold-based bone regeneration in situ.
文摘A kind of interlaminar film with carbon nanotubes inserted into polyether ketone with cardo was used for lightning strike protection of composite laminates. The distribution of the interlaminar film was investigated by experimental and numerical methods. Artificial lightning strike tests were conducted for 12-film carbon nanotube and traditional surface silver coating protected specimens. Then corresponding finite element models(FEMs) were established to analyze the lightning strike effect and validated by the experimental results. Based on the FEMs, the number, distribution and thickness of interlaminar film were investigated in order to obtain equivalent protection effect with the traditional surface silver coating. The results show that only the first two layers were damaged for the surface silver coating protected specimen, while 5 layers were ablated for the 12-film protected specimen. Lightning strike damage area of the laminate protected with 5-film carbon nanotube is almost the same as that of the laminate protected with 12-film carbon nanotube. Compared with traditional surface silver coating protection, one film protection with thickness of 360 lm can make the laminate to obtain equivalent damage depth, 54.8% smaller damage area and 58% less additional weight. And reparability of the laminate is better than that of the laminate protected with 5 interlaminar films.
基金supported by the fund of Natural Science Foundation of China(Nos.11872196,11902130).
文摘The residual stress is formed in YBa_(2)Cu_(3)O_(7-δ) (YBCO) bulk superconductors,which undergoes a complex fabrication process and experienced a huge temperature change about 1000℃.The residual stress may result in micro-cracks in YBCO bulks and cause degradation of its superconducting and mechanical properties.It will be greatly helpful to reform the structural designs if the distribution of residual stress in YBCO bulk can be investigated.The traditional method of measuring residual stress does not apply to oxide ceramics as they are brittle materials.In this paper,a YBCO bulk was sliced into pieces of several millimeters in height,which could thus be treated as a plane-stress problem.The residual stress and principal stress angle for YBCO bulk have been obtained by an artificial hole-drilling method with very low speed.
