Motor endplates(MEPs) are important sites of information exchange between motor neurons and skeletal muscle, and are distributed in an organized pattern of lamellae in the muscle. Delayed repair of peripheral nerve in...Motor endplates(MEPs) are important sites of information exchange between motor neurons and skeletal muscle, and are distributed in an organized pattern of lamellae in the muscle. Delayed repair of peripheral nerve injury typically results in unsatisfactory functional recovery because of MEP degeneration. In this study, the mouse tibial nerve was transected and repaired with a biodegradable chitin conduit, immediately following or 1 or 3 months after the injury. Fluorescent α-bungarotoxin was injected to label MEPs. Tissue optical clearing combined with light-sheet microscopy revealed that MEPs were distributed in an organized pattern of lamellae in skeletal muscle after delayed repair for 1 and 3 months. However, the total number of MEPs, the number of MEPs per lamellar cluster, and the maturation of single MEPs in gastrocnemius muscle gradually decreased with increasing denervation time. These findings suggest that delayed repair can restore the spatial distribution of MEPs, but it has an adverse effect on the homogeneity of MEPs in the lamellar clusters and the total number of MEPs in the target muscle. The study procedures were approved by the Animal Ethics Committee of the Peking University People's Hospital(approval No. 2019 PHC015) on April 8, 2019.展开更多
As one of important members of refractory materials,tungsten phosphide(WP)holds great potential for fundamental study and industrial applications in many fields of science and technology,due to its excellent propertie...As one of important members of refractory materials,tungsten phosphide(WP)holds great potential for fundamental study and industrial applications in many fields of science and technology,due to its excellent properties such as superconductivity and as-predicted topological band structure.However,synthesis of high-quality WP crystals is still a challenge by using tradition synthetic methods,because the synthesis temperature for growing its large crystals is very stringently required to be as high as 3000℃,which is far beyond the temperature capability of most laboratory-based devices for crystal growth.In addition,high temperature often induces the decomposition of metal phosphides,leading to off-stoichiometric samples based on which the materials'intrinsic properties cannot be explored.In this work,we report a high-pressure synthesis of single-crystal WP through a direct crystallization from cooling the congruent W-P melts at 5 GPa and^3200℃.In combination of x-ray diffraction,electron microscope,and thermal analysis,the crystal structure,morphology,and stability of recovered sample are well investigated.The final product is phase-pure and nearly stoichiometric WP in a single-crystal form with a large grain size,in excess of one millimeter,thus making it feasible to implement most experimental measurements,especially,for the case where a large crystal is required.Success in synthesis of high-quality WP crystals at high pressure can offer great opportunities for determining their intrinsic properties and also making more efforts to study the family of transition-metal phosphides.展开更多
The quadrilateral plate(QP)is an essential structure of the inner wall of the acetabulum,an important weight-bearing joint of the human body,which is often involved in acetabular fractures.The operative exposure,reduc...The quadrilateral plate(QP)is an essential structure of the inner wall of the acetabulum,an important weight-bearing joint of the human body,which is often involved in acetabular fractures.The operative exposure,reduction and fixation of QP fractures have always been the difficulties in orthopedics due to the special morphological structure and anatomical features of the QP.Fortunately,there have been many effective methods and instruments developed for QP exposure,reduction and fixation by virtue of the combined efforts of numerous orthopedists.At the same time,each method presents with its own advantages and disadvantages,resulting in different prognoses.It is necessary to have a thorough understanding of the anatomy,radiology and fixation techniques of the QP in terms of patient prognosis optimization.In this paper,the anatomical features,definition and classification of QP,operative approach selection,implant internal fixation methods and efficacy were reviewed.展开更多
BACKGROUND The corona virus disease 2019(COVID-19)has been a pandemic for more than one year and estimated to affect the whole world in the near future.CASE SUMMARY Here we reported that one COVID-19 patient with vesi...BACKGROUND The corona virus disease 2019(COVID-19)has been a pandemic for more than one year and estimated to affect the whole world in the near future.CASE SUMMARY Here we reported that one COVID-19 patient with vesicles was treated by bullectomy.The patient’s perioperative laboratory tests were analyzed.The pathological findings of bullectomy were described and compared with those of common bulla cases.CONCLUSION This patient with vesicles underwent bullectomy and had a poor prognosis.He showed diffuse alveolar damage and extensive necrosis in bullectomy specimen.We hope our report will be of interest for clinicians who will treat COVID-19 patients in the future.展开更多
Obtaining small carbides is crucial but difficult for high-speed steels.A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was prop...Obtaining small carbides is crucial but difficult for high-speed steels.A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was proposed.The morphologies and properties of eutectic carbides formed at different cooling rates were investigated by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),transmission electron microscopy(TEM),electron back-scattered diffraction(EBSD)and differential scanning calorimeter(DSC).The results show that eutectic carbides change from a lamellar shape into a curved-rod shape as cooling rate increases.Despite different morphologies,the two carbides are both of M_2C type with a hexagonal close-packed structure and display a single crystal orientation in one eutectic colony.The morphology of M_2C mainly depends on the growing process of eutectic carbides,which is strongly influenced by cooling rate.Compared with lamellar carbides,M_2C carbides with curved-rod shapes are less stable,and decompose into M_6 C and MC at lower temperatures.They are more inclined to spheroidize during heating,which ultimately and distinguishably refines the carbide dimensions.As small carbides are much easier to dissolve into matrices during austenization,the process described herein improves the supersaturation of alloying elements in martensite,which leads to an increment of hardness in M42 steel.展开更多
The morphology,microstructure and decomposition behavior of M_2C carbides in high speed steels with different chemical compositions have been investigated by scanning electron microscopy,transmission electron microsco...The morphology,microstructure and decomposition behavior of M_2C carbides in high speed steels with different chemical compositions have been investigated by scanning electron microscopy,transmission electron microscopy,electron backscatter diffraction and X-ray diffraction.The results show that the morphology and substructure of M_2C carbides are very sensitive to chemical compositions of high speed steels.M_2C carbides present the plate-like shape in tungsten-molybdenum steel and present the polycrystal orientation in the eutectic cell.In contrast,they show the fibrous shape in molybdenum-base steel and exhibit the monocrystal orientation.Plate-like and fibrous M_2C carbides are both metastable and decompose into M6 C together with MC at high temperatures.MC nucleates inside the plate-like M_2C while it is formed at the fibrous M2C/matrix interface during the decomposition process.Such differences are expected to arise from different compositions of plate-like and fibrous M_2C carbides.展开更多
The isothermal oxidation behavior of a new Refree nickel-based single-crystal superalloy in air at 950 ℃ for 200 h was studied by scanning electron microscopy(SEM)with energy-dispersive spectroscopy(EDS)and X-ray dif...The isothermal oxidation behavior of a new Refree nickel-based single-crystal superalloy in air at 950 ℃ for 200 h was studied by scanning electron microscopy(SEM)with energy-dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The results indicate that oxidation kinetics obeys parabolic law approximately,and the mass gain increases rapidly during initial oxidation stage and then gradually slows down.The oxidation scales are composed of three layers:the outer layer mainly consists of NiO with a small amount of CoO;the intermediate layer is mainly composed of Cr_2O_3 with a small amount of spinel compounds such as CrTaO_4,NiCr_2O_4,CoCrAl_2O_4,CoAl_2O_4,and NiAl_2O_4;and the inner layer is composed of Al_2O_3.Inner Al_2O_3 layer suppresses the diffusion of elements between oxygen and alloy elements,slows down the alloy oxidation speed,and also suppresses the growth of the oxide scale and reduces the oxidation rate,which is agreeable with the oxidation kinetics.展开更多
Four new polyketide decalin derivatives,penicisteck acids A-D(1-4),and three new nitrogenous compounds(7-9)z together with eight previously reported compounds,were isolated from the mangrove endophytic fungus Penicill...Four new polyketide decalin derivatives,penicisteck acids A-D(1-4),and three new nitrogenous compounds(7-9)z together with eight previously reported compounds,were isolated from the mangrove endophytic fungus Penicillium steckii SCSIO 41025.展开更多
基金supported by the National Natural Science Foundation of China,Nos.82072162(to XFY),81971177the Natural Science Foundation of Beijing of China,No.7192215(to XFY)。
文摘Motor endplates(MEPs) are important sites of information exchange between motor neurons and skeletal muscle, and are distributed in an organized pattern of lamellae in the muscle. Delayed repair of peripheral nerve injury typically results in unsatisfactory functional recovery because of MEP degeneration. In this study, the mouse tibial nerve was transected and repaired with a biodegradable chitin conduit, immediately following or 1 or 3 months after the injury. Fluorescent α-bungarotoxin was injected to label MEPs. Tissue optical clearing combined with light-sheet microscopy revealed that MEPs were distributed in an organized pattern of lamellae in skeletal muscle after delayed repair for 1 and 3 months. However, the total number of MEPs, the number of MEPs per lamellar cluster, and the maturation of single MEPs in gastrocnemius muscle gradually decreased with increasing denervation time. These findings suggest that delayed repair can restore the spatial distribution of MEPs, but it has an adverse effect on the homogeneity of MEPs in the lamellar clusters and the total number of MEPs in the target muscle. The study procedures were approved by the Animal Ethics Committee of the Peking University People's Hospital(approval No. 2019 PHC015) on April 8, 2019.
基金the National Key Research and Development Program of China(Grant Nos.2016YFA0401503 and 2018YFA0305700)the National Natural Science Foundation of China(Grant No.11575288)+4 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2016006)the Key Research Platforms and Research Projects of Universities in Guangdong Province,China(Grant No.2018KZDXM062)the Guangdong Innovative&Entrepreneurial Research Team Program,China(Grant No.2016ZT06C279)the Shenzhen Peacock Plan,China(Grant No.KQTD2016053019134356)the Shenzhen Development&Reform Commission Foundation for Novel Nano-Material Sciences,China,the Research Platform for Crystal Growth&Thin-Film Preparation at SUST,China,and the Shenzhen Development and Reform Commission Foundation for Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressure,China.
文摘As one of important members of refractory materials,tungsten phosphide(WP)holds great potential for fundamental study and industrial applications in many fields of science and technology,due to its excellent properties such as superconductivity and as-predicted topological band structure.However,synthesis of high-quality WP crystals is still a challenge by using tradition synthetic methods,because the synthesis temperature for growing its large crystals is very stringently required to be as high as 3000℃,which is far beyond the temperature capability of most laboratory-based devices for crystal growth.In addition,high temperature often induces the decomposition of metal phosphides,leading to off-stoichiometric samples based on which the materials'intrinsic properties cannot be explored.In this work,we report a high-pressure synthesis of single-crystal WP through a direct crystallization from cooling the congruent W-P melts at 5 GPa and^3200℃.In combination of x-ray diffraction,electron microscope,and thermal analysis,the crystal structure,morphology,and stability of recovered sample are well investigated.The final product is phase-pure and nearly stoichiometric WP in a single-crystal form with a large grain size,in excess of one millimeter,thus making it feasible to implement most experimental measurements,especially,for the case where a large crystal is required.Success in synthesis of high-quality WP crystals at high pressure can offer great opportunities for determining their intrinsic properties and also making more efforts to study the family of transition-metal phosphides.
文摘The quadrilateral plate(QP)is an essential structure of the inner wall of the acetabulum,an important weight-bearing joint of the human body,which is often involved in acetabular fractures.The operative exposure,reduction and fixation of QP fractures have always been the difficulties in orthopedics due to the special morphological structure and anatomical features of the QP.Fortunately,there have been many effective methods and instruments developed for QP exposure,reduction and fixation by virtue of the combined efforts of numerous orthopedists.At the same time,each method presents with its own advantages and disadvantages,resulting in different prognoses.It is necessary to have a thorough understanding of the anatomy,radiology and fixation techniques of the QP in terms of patient prognosis optimization.In this paper,the anatomical features,definition and classification of QP,operative approach selection,implant internal fixation methods and efficacy were reviewed.
文摘BACKGROUND The corona virus disease 2019(COVID-19)has been a pandemic for more than one year and estimated to affect the whole world in the near future.CASE SUMMARY Here we reported that one COVID-19 patient with vesicles was treated by bullectomy.The patient’s perioperative laboratory tests were analyzed.The pathological findings of bullectomy were described and compared with those of common bulla cases.CONCLUSION This patient with vesicles underwent bullectomy and had a poor prognosis.He showed diffuse alveolar damage and extensive necrosis in bullectomy specimen.We hope our report will be of interest for clinicians who will treat COVID-19 patients in the future.
基金Item Sponsored by National Natural Science Foundation of China(51301038,51201031,51371050)Industry-Academia-Research Program of Jiangsu Province of China(BY2014127-03)+1 种基金Natural Science Foundation of Jiangsu Province of China(BK20141306)Jiangsu Province Key Laboratory of High-end Structural Materials of China(hsm1404)
文摘Obtaining small carbides is crucial but difficult for high-speed steels.A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was proposed.The morphologies and properties of eutectic carbides formed at different cooling rates were investigated by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),transmission electron microscopy(TEM),electron back-scattered diffraction(EBSD)and differential scanning calorimeter(DSC).The results show that eutectic carbides change from a lamellar shape into a curved-rod shape as cooling rate increases.Despite different morphologies,the two carbides are both of M_2C type with a hexagonal close-packed structure and display a single crystal orientation in one eutectic colony.The morphology of M_2C mainly depends on the growing process of eutectic carbides,which is strongly influenced by cooling rate.Compared with lamellar carbides,M_2C carbides with curved-rod shapes are less stable,and decompose into M_6 C and MC at lower temperatures.They are more inclined to spheroidize during heating,which ultimately and distinguishably refines the carbide dimensions.As small carbides are much easier to dissolve into matrices during austenization,the process described herein improves the supersaturation of alloying elements in martensite,which leads to an increment of hardness in M42 steel.
基金funded by National Natural Science Foundation of China(51301038,51371050)Industry-Academia-Research Program of Jiangsu Province of China(BY2014127-03)+2 种基金Natural Science Foundation of Jiangsu Province of China(BK20141306)Key Research Program of Jiangsu Province of China(BE2016154)Jiangsu Province Key Laboratory of High-end Structural Materials of China(hsm1404)
文摘The morphology,microstructure and decomposition behavior of M_2C carbides in high speed steels with different chemical compositions have been investigated by scanning electron microscopy,transmission electron microscopy,electron backscatter diffraction and X-ray diffraction.The results show that the morphology and substructure of M_2C carbides are very sensitive to chemical compositions of high speed steels.M_2C carbides present the plate-like shape in tungsten-molybdenum steel and present the polycrystal orientation in the eutectic cell.In contrast,they show the fibrous shape in molybdenum-base steel and exhibit the monocrystal orientation.Plate-like and fibrous M_2C carbides are both metastable and decompose into M6 C together with MC at high temperatures.MC nucleates inside the plate-like M_2C while it is formed at the fibrous M2C/matrix interface during the decomposition process.Such differences are expected to arise from different compositions of plate-like and fibrous M_2C carbides.
基金financially supported by Jiangsu Province Key Technology R&D(Industry)Program(No.BE201217)the Science and Technology Innovation Fund Program(Nos.CX2011028 and CX2011029)+1 种基金the Cooperative Innovation Fund of Jiangsu Province(No.BY2014004-09)the Foundation of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(No.ASMA201403)
文摘The isothermal oxidation behavior of a new Refree nickel-based single-crystal superalloy in air at 950 ℃ for 200 h was studied by scanning electron microscopy(SEM)with energy-dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The results indicate that oxidation kinetics obeys parabolic law approximately,and the mass gain increases rapidly during initial oxidation stage and then gradually slows down.The oxidation scales are composed of three layers:the outer layer mainly consists of NiO with a small amount of CoO;the intermediate layer is mainly composed of Cr_2O_3 with a small amount of spinel compounds such as CrTaO_4,NiCr_2O_4,CoCrAl_2O_4,CoAl_2O_4,and NiAl_2O_4;and the inner layer is composed of Al_2O_3.Inner Al_2O_3 layer suppresses the diffusion of elements between oxygen and alloy elements,slows down the alloy oxidation speed,and also suppresses the growth of the oxide scale and reduces the oxidation rate,which is agreeable with the oxidation kinetics.
基金This work was supported by the Key-Area Research and Development Program of Guangdong Province(2O2OB1111O3OOO5)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guang-zhou)(GML2019ZD0406)+4 种基金the National Natural Science Foundation of China(Nos.U20A20101,22007019,81973235)the Special Fund for Bagui Scholars of Guangxi(05019055)the Natural Science Foundation of Guangxi(Nos.2020GXNSFBA159001,2020GXNSFGA297002)the Specific Research Project of Guangxi for Research Bases and Talents(AD20297003)the Open Project of CAS Key Laboratory of Tropical Marine Bio-resources and Ecology(LMB20211005).
文摘Four new polyketide decalin derivatives,penicisteck acids A-D(1-4),and three new nitrogenous compounds(7-9)z together with eight previously reported compounds,were isolated from the mangrove endophytic fungus Penicillium steckii SCSIO 41025.
