We introduce a modification of reflectron time-of-flight mass spectrometer for laser photodissociation of mass-selected ions. In our apparatus, the ions of interests were selected by a mass gate near the first space f...We introduce a modification of reflectron time-of-flight mass spectrometer for laser photodissociation of mass-selected ions. In our apparatus, the ions of interests were selected by a mass gate near the first space focus point and decelerated right after the mass gate, were then crossed by a laser beam for dissociation. The daughter ions and surviving parent ions were re-accelerated and analyzed by the reflectron time-of-flight mass spectrometer. Compared to the designs reported by other research groups, our selection-deceleration-dissociation-reacceleration approach has better daughter-parent-ions-separation, easier laser timing, and better overlapping between the ion beam and laser beam. We also conducted detailed cal- culations on the parent ion and daughter ion flight times, and provided a simplified formula for the calibration of daughter ion mass.展开更多
BACKGROUND Few reports have described lumbar foraminal stenosis-induced radiculopathy after treatment by full-endoscopic spine surgery(FESS)combined with percutaneous vertebroplasty(PVP)in patients with vertebral comp...BACKGROUND Few reports have described lumbar foraminal stenosis-induced radiculopathy after treatment by full-endoscopic spine surgery(FESS)combined with percutaneous vertebroplasty(PVP)in patients with vertebral compression fractures.We herein report such a case,including the patient’s treatment process and doctor’s surgical experience.CASE SUMMARY A 79-year-old man presented with symptoms of radiculopathy after sustaining L4 vertebral compression fractures.Imaging and physical examination revealed L4 vertebral compression fractures combined with L3/4 Lumbar foraminal stenosis(LFS).The patient’s symptoms were low back pain with pain in the lateral left leg.Although many reports have described radiculopathy induced by osteoporotic vertebral compression fractures,the use of FESS combined with PVP has rarely been reported.This case report indicates that the combination of FESS and PVP is a safe and effective approach for the treatment of LFS-induced radiculopathy after vertebral compression fractures.This minimally invasive technique has great potential to replace traditional lumbar fixation and decompression surgery.Thus,we suggest the continued accumulation of similar cases to discuss the wider application of FESS.CONCLUSION For patients with osteoporotic vertebral compression fracture(OVCF)and LFS,PVP and FESS can be used to restore the vertebral height and reduce the pressure around the intervertebral foramen.Additionally,the combination of FESS and PVP can treat the pain or numbness of the low back and lower limbs and allow for recovery in a short time with excellent postoperative effects.In general,FESS is a good treatment for radiculopathy caused by foraminal stenosis after OVCF.展开更多
Veins are easy to obtain,have low immunogenicity,and induce a relatively weak inflammatory response.Therefore,veins have the potential to be used as conduits for nerve regeneration.However,because of the presence of v...Veins are easy to obtain,have low immunogenicity,and induce a relatively weak inflammatory response.Therefore,veins have the potential to be used as conduits for nerve regeneration.However,because of the presence of venous valves and the great elasticity of the venous wall,the vein is not conducive to nerve regeneration.In this study,a novel tissue engineered nerve graft was constructed by combining normal dissected nerve microtissue with an autologous vein graft for repairing 10-mm peripheral nerve defects in rats.Compared with rats given the vein graft alone,rats given the tissue engineered nerve graft had an improved sciatic static index,and a higher amplitude and shorter latency of compound muscle action potentials.Furthermore,rats implanted with the microtissue graft had a higher density and thickness of myelinated nerve fibers and reduced gastrocnemius muscle atrophy compared with rats implanted with the vein alone.However,the tissue engineered nerve graft had a lower ability to repair the defect than autogenous nerve transplantation.In summary,although the tissue engineered nerve graft constructed with autologous vein and nerve microtissue is not as effective as autologous nerve transplantation for repairing long-segment sciatic nerve defects,it may nonetheless have therapeutic potential for the clinical repair of long sciatic nerve defects.This study was approved by the Experimental Animal Ethics Committee of Chinese PLA General Hospital(approval No.2016-x9-07)on September 7,2016.展开更多
Investigating the structures and properties of Au-Ge mixed clusters can give insight into the microscopic mechanisms in gold-catalyzed Ge films and can also provide valuable information for the production of germanium...Investigating the structures and properties of Au-Ge mixed clusters can give insight into the microscopic mechanisms in gold-catalyzed Ge films and can also provide valuable information for the production of germanium-based functional materials. In this work, size-selected anion photoelectron spectroscopy and theoretical calculations were used to explore the structural evolution and electronic properties of Au2Gen^-/0 (n=1-8) clusters. It is found that the two Au atoms in Au2Gen^-/0 (n=1-8) showed high coordination numbers and weak aurophilic interactions. The global minima of Au2Gen- anions and Au2Gen neutrals are in spin doublet and singlet states, respectively. Au2Gen- anions and Au2Gen neutrals showed similar structural features, except for Au2Ge4^-/0 and Au2Ge5^-/0. The C2v symmetric V-shaped structure is observed for Au2Ge1^-/0, while Au2Ge2^-/0 has a C2v symmetric dibridged structure. Au2Ge3^-/0 can be viewed as the two Au atoms attached to different Ge-Ge bonds of Ge3 triangle. Au2Ge4- has two Au atoms edge-capping Ge4 tetrahedron, while Au2Ge4 neutral adopts a C2v symmetric double Au atoms face-capping Ge4 rhombus. Au2Ge5-8^-/0 show triangular, tetragonal, and pentagonal prism-based geometries. Au2Ge6 adopts a C2v symmetric tetragonal prism structure and exhibits σ plus π double bonding characters.展开更多
We measured the photoelectron spectra of AuC_(n)^(-)(n=3-8)and conducted theoretical study on the structures and properties of AuC_(n)^(-/0)(n=3-8).It is found that the photoelectron spectra of AuC_(n)^(-)exhibit odd-...We measured the photoelectron spectra of AuC_(n)^(-)(n=3-8)and conducted theoretical study on the structures and properties of AuC_(n)^(-/0)(n=3-8).It is found that the photoelectron spectra of AuC_(n)^(-)exhibit odd-even alternation.The spectral features of AuC_(3)^(-),AuC_(5)^(-),and AuC_(7)^(-)are much broader than those of AuC_(4)^(-),AuC_(6)^(-),and AuC_(5)^(-).The vertical detachment energies of AuC_(3)^(-),AuC_(5)^(-),and AuC_(7)^(-)are lower than those of AuC_(4)^(-),AuC_(6)^(-),and AuCs_(8)^(-).The most stable structures of AuC_(n)^(-)(n=3-8)are chain structures.The most stable structures of neutral AuC_(n)(n=3-8)are linear structures except that those of AuC_(3) and AuC_(5) are slightly bent.The calculated∠AuCC angles,Au-C bond lengths,and the charges on Au atom also show odd-even alternations,consistent with the experimental observations.展开更多
Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies,and understanding such catalytic properties requires knowledge of their precise geome...Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies,and understanding such catalytic properties requires knowledge of their precise geometry,determination of which is challenging,particularly for clusters formed by multiple elements.In this study,we investigate the geometries and electronic structures of binary V_(n)C_(3)-(n=1-6)clusters and their neutrals using photoelectron spectroscopy and theoretical calculations based on density functional theory.The adiabatic detachment energies of V_(n)C_(3)-,or equally,the electron affinities of V_(n)C_(3),have been determined from the measured photoelectron spectra.Theoretical calculations reveal that the carbon atoms become separate when the number of V atoms increases in the clusters,i.e.,the C-C interactions present in small clusters are replaced by V-C and/or V-V interactions in larger ones.We further explore the composition dependent formation of cubic or cube-like structures in 8-atom VnCm(n+m=8)clusters.展开更多
We measured the photoelectron spectra of Al_(n)C_(4)^(−)(n=2−4)clusters by using size-selected anion photoelectron spectroscopy.The structures of Al_(n)C_(4)^(−/0)(n=2−4)clusters were explored with quantum chemistry c...We measured the photoelectron spectra of Al_(n)C_(4)^(−)(n=2−4)clusters by using size-selected anion photoelectron spectroscopy.The structures of Al_(n)C_(4)^(−/0)(n=2−4)clusters were explored with quantum chemistry calculations and were determined by comparing the theoretical results with the experimental spectra.It is found that the most stable structure of Al_(2)C_(4)^(−) anion is a C_(2v)symmetry planar structure with two Al atoms interacting with two C_(2)units.In addition,Al_(2)C_(4)^(−) anion also has a D∞h symmetry linear structure with two Al atoms located at the two ends of a C_(4)chain,which is slightly higher in energy than the planar structure.The most stable structure of neutral Al_(2)C_(4)has a D∞h symmetry linear structure.The most stable structure of Al_(3)C_(4)^(−) anion is a planar structure with three Al atoms interacting with two C_(2)units.Whereas neutral Al_(3)C_(4)cluster has a C_(2v)symmetric V-shaped bent structure.The global minima structures of both Al_(4)C_(4)^(−) and neutral Al_(4)C_(4)are C_(2)h symmetry planar structures with four Al atoms interacting with the ends of two C_(2)units.Adaptive natural density partitioning analyses of Al_(n)C_(4)^(−)(n=2−4)clusters show that the interactions between the Al atoms and C_(2)units have bothσandπcharacters.展开更多
We employ nondestructive evaluation involving AC field measurement in detecting and identifying metal barcode labels,providing a reference for design.Using the magnetic scalar potential boundary condition at notches i...We employ nondestructive evaluation involving AC field measurement in detecting and identifying metal barcode labels,providing a reference for design.Using the magnetic scalar potential boundary condition at notches in thin-skin field theory and 2D Fourier transform,we introduce an analytical model for the magnetic scalar potential induced by the interaction of a high-frequency inducer with a metal barcode label containing multiple narrow saw-cut notches,and then calculate the magnetic field in the free space above the metal barcode label.With the simulations of the magnetic field,qualitative analysis is given for the effects on detecting and identifying metal barcode labels,which are caused by metal material,notch characteristics,exciting inducer properties,and other factors that can be used in metal barcode label design as reference.Simulation results are in good accordance with experiment results.展开更多
基金V. ACKNOWLEDGMENTS This work supported by the National Natural Science Foundation of China （No.20853001）. We thank Professor Qi-he Zhu and Professor Zhen Gao for valuable discussions.
文摘We introduce a modification of reflectron time-of-flight mass spectrometer for laser photodissociation of mass-selected ions. In our apparatus, the ions of interests were selected by a mass gate near the first space focus point and decelerated right after the mass gate, were then crossed by a laser beam for dissociation. The daughter ions and surviving parent ions were re-accelerated and analyzed by the reflectron time-of-flight mass spectrometer. Compared to the designs reported by other research groups, our selection-deceleration-dissociation-reacceleration approach has better daughter-parent-ions-separation, easier laser timing, and better overlapping between the ion beam and laser beam. We also conducted detailed cal- culations on the parent ion and daughter ion flight times, and provided a simplified formula for the calibration of daughter ion mass.
基金Supported by National Natural Science Foundation of China,No.81972108.
文摘BACKGROUND Few reports have described lumbar foraminal stenosis-induced radiculopathy after treatment by full-endoscopic spine surgery(FESS)combined with percutaneous vertebroplasty(PVP)in patients with vertebral compression fractures.We herein report such a case,including the patient’s treatment process and doctor’s surgical experience.CASE SUMMARY A 79-year-old man presented with symptoms of radiculopathy after sustaining L4 vertebral compression fractures.Imaging and physical examination revealed L4 vertebral compression fractures combined with L3/4 Lumbar foraminal stenosis(LFS).The patient’s symptoms were low back pain with pain in the lateral left leg.Although many reports have described radiculopathy induced by osteoporotic vertebral compression fractures,the use of FESS combined with PVP has rarely been reported.This case report indicates that the combination of FESS and PVP is a safe and effective approach for the treatment of LFS-induced radiculopathy after vertebral compression fractures.This minimally invasive technique has great potential to replace traditional lumbar fixation and decompression surgery.Thus,we suggest the continued accumulation of similar cases to discuss the wider application of FESS.CONCLUSION For patients with osteoporotic vertebral compression fracture(OVCF)and LFS,PVP and FESS can be used to restore the vertebral height and reduce the pressure around the intervertebral foramen.Additionally,the combination of FESS and PVP can treat the pain or numbness of the low back and lower limbs and allow for recovery in a short time with excellent postoperative effects.In general,FESS is a good treatment for radiculopathy caused by foraminal stenosis after OVCF.
基金This work was supported by the National Natural Science Foundation of China,Nos.31771052(to YW),81671684(to YXW),81871788(to CZ)National Key Research and Development Program of China,Nos.2017YFA0104702,2017YFA0104703+3 种基金the Natural Science Foundation of Beijing of China,No.7172202(to YW)PLA Youth Training Project for Medical Science of China,No.16QNP144(to YW),the Project for Science and Technology Leader of Anhui Province of China,No.2018H177(to CZ)Funding of“Panfeng”Innovation Team Project for Scientifc Research of Yijishan Hospital,Wannan Medical College,China,No.PF2019007(to HGX)Funding of“Peak”Training Program for Scientifc Research of Yijishan Hospital,Wannan Medical College,China,No.GF2019T02(to HGX).
文摘Veins are easy to obtain,have low immunogenicity,and induce a relatively weak inflammatory response.Therefore,veins have the potential to be used as conduits for nerve regeneration.However,because of the presence of venous valves and the great elasticity of the venous wall,the vein is not conducive to nerve regeneration.In this study,a novel tissue engineered nerve graft was constructed by combining normal dissected nerve microtissue with an autologous vein graft for repairing 10-mm peripheral nerve defects in rats.Compared with rats given the vein graft alone,rats given the tissue engineered nerve graft had an improved sciatic static index,and a higher amplitude and shorter latency of compound muscle action potentials.Furthermore,rats implanted with the microtissue graft had a higher density and thickness of myelinated nerve fibers and reduced gastrocnemius muscle atrophy compared with rats implanted with the vein alone.However,the tissue engineered nerve graft had a lower ability to repair the defect than autogenous nerve transplantation.In summary,although the tissue engineered nerve graft constructed with autologous vein and nerve microtissue is not as effective as autologous nerve transplantation for repairing long-segment sciatic nerve defects,it may nonetheless have therapeutic potential for the clinical repair of long sciatic nerve defects.This study was approved by the Experimental Animal Ethics Committee of Chinese PLA General Hospital(approval No.2016-x9-07)on September 7,2016.
基金supported by the National Natural Science Foundation of China (No.21273246 and No.21103202)the Chinese Academy of Sciences (No.QYZDB-SSW-SLH024)+3 种基金the Natural Science Foundation of Shandong Province of China (No.ZR2018BB040)Open Funds of Beijing National Laboratory for Molecular Sciences (No.BNLMS201804)Research Start-up Funds (Doctoral Science Foundation) of Heze University (No.XY18BS02)Chinese Academy of Sciences President’s International Fellowship Initiative (PIFI) (No.2018VMA0011)
文摘Investigating the structures and properties of Au-Ge mixed clusters can give insight into the microscopic mechanisms in gold-catalyzed Ge films and can also provide valuable information for the production of germanium-based functional materials. In this work, size-selected anion photoelectron spectroscopy and theoretical calculations were used to explore the structural evolution and electronic properties of Au2Gen^-/0 (n=1-8) clusters. It is found that the two Au atoms in Au2Gen^-/0 (n=1-8) showed high coordination numbers and weak aurophilic interactions. The global minima of Au2Gen- anions and Au2Gen neutrals are in spin doublet and singlet states, respectively. Au2Gen- anions and Au2Gen neutrals showed similar structural features, except for Au2Ge4^-/0 and Au2Ge5^-/0. The C2v symmetric V-shaped structure is observed for Au2Ge1^-/0, while Au2Ge2^-/0 has a C2v symmetric dibridged structure. Au2Ge3^-/0 can be viewed as the two Au atoms attached to different Ge-Ge bonds of Ge3 triangle. Au2Ge4- has two Au atoms edge-capping Ge4 tetrahedron, while Au2Ge4 neutral adopts a C2v symmetric double Au atoms face-capping Ge4 rhombus. Au2Ge5-8^-/0 show triangular, tetragonal, and pentagonal prism-based geometries. Au2Ge6 adopts a C2v symmetric tetragonal prism structure and exhibits σ plus π double bonding characters.
基金supported by the Beijing Municipal Science&Technology Commission(No.Z191100007219009)。
文摘We measured the photoelectron spectra of AuC_(n)^(-)(n=3-8)and conducted theoretical study on the structures and properties of AuC_(n)^(-/0)(n=3-8).It is found that the photoelectron spectra of AuC_(n)^(-)exhibit odd-even alternation.The spectral features of AuC_(3)^(-),AuC_(5)^(-),and AuC_(7)^(-)are much broader than those of AuC_(4)^(-),AuC_(6)^(-),and AuC_(5)^(-).The vertical detachment energies of AuC_(3)^(-),AuC_(5)^(-),and AuC_(7)^(-)are lower than those of AuC_(4)^(-),AuC_(6)^(-),and AuCs_(8)^(-).The most stable structures of AuC_(n)^(-)(n=3-8)are chain structures.The most stable structures of neutral AuC_(n)(n=3-8)are linear structures except that those of AuC_(3) and AuC_(5) are slightly bent.The calculated∠AuCC angles,Au-C bond lengths,and the charges on Au atom also show odd-even alternations,consistent with the experimental observations.
基金the Doctoral Start-up Funding of Zhengzhou University of Light Industry(No.2017BSJJ030)Henan Province Science Fund for Excellent Young Scholars(No.202300410494)+4 种基金the Beijing Municipal Science and Technology Commission(No.Z191100007219009)for supportsthe VSC(Flemish Supercomputer Center),funded by the Research Foundation-Flanders(FWO)the Flemish Government-department EWIthe support of Xi’an Jiaotong University via the“Young Talent Support Plan”the“Fundamental Research Funds for Central Universities”。
文摘Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies,and understanding such catalytic properties requires knowledge of their precise geometry,determination of which is challenging,particularly for clusters formed by multiple elements.In this study,we investigate the geometries and electronic structures of binary V_(n)C_(3)-(n=1-6)clusters and their neutrals using photoelectron spectroscopy and theoretical calculations based on density functional theory.The adiabatic detachment energies of V_(n)C_(3)-,or equally,the electron affinities of V_(n)C_(3),have been determined from the measured photoelectron spectra.Theoretical calculations reveal that the carbon atoms become separate when the number of V atoms increases in the clusters,i.e.,the C-C interactions present in small clusters are replaced by V-C and/or V-V interactions in larger ones.We further explore the composition dependent formation of cubic or cube-like structures in 8-atom VnCm(n+m=8)clusters.
基金supported by the Beijing Municipal Science&Technology Commission(No.Z191100007219009)the National Natural Science Foundation of China(No.21773255)。
文摘We measured the photoelectron spectra of Al_(n)C_(4)^(−)(n=2−4)clusters by using size-selected anion photoelectron spectroscopy.The structures of Al_(n)C_(4)^(−/0)(n=2−4)clusters were explored with quantum chemistry calculations and were determined by comparing the theoretical results with the experimental spectra.It is found that the most stable structure of Al_(2)C_(4)^(−) anion is a C_(2v)symmetry planar structure with two Al atoms interacting with two C_(2)units.In addition,Al_(2)C_(4)^(−) anion also has a D∞h symmetry linear structure with two Al atoms located at the two ends of a C_(4)chain,which is slightly higher in energy than the planar structure.The most stable structure of neutral Al_(2)C_(4)has a D∞h symmetry linear structure.The most stable structure of Al_(3)C_(4)^(−) anion is a planar structure with three Al atoms interacting with two C_(2)units.Whereas neutral Al_(3)C_(4)cluster has a C_(2v)symmetric V-shaped bent structure.The global minima structures of both Al_(4)C_(4)^(−) and neutral Al_(4)C_(4)are C_(2)h symmetry planar structures with four Al atoms interacting with the ends of two C_(2)units.Adaptive natural density partitioning analyses of Al_(n)C_(4)^(−)(n=2−4)clusters show that the interactions between the Al atoms and C_(2)units have bothσandπcharacters.
基金supported by the National Natural Science Foundation of China(No.61271247)
文摘We employ nondestructive evaluation involving AC field measurement in detecting and identifying metal barcode labels,providing a reference for design.Using the magnetic scalar potential boundary condition at notches in thin-skin field theory and 2D Fourier transform,we introduce an analytical model for the magnetic scalar potential induced by the interaction of a high-frequency inducer with a metal barcode label containing multiple narrow saw-cut notches,and then calculate the magnetic field in the free space above the metal barcode label.With the simulations of the magnetic field,qualitative analysis is given for the effects on detecting and identifying metal barcode labels,which are caused by metal material,notch characteristics,exciting inducer properties,and other factors that can be used in metal barcode label design as reference.Simulation results are in good accordance with experiment results.
