The Moon provides a unique environment for investigating nearby astrophysical events such as supernovae.Lunar samples retain valuable information from these events,via detectable long-lived“fingerprint”radionuclides...The Moon provides a unique environment for investigating nearby astrophysical events such as supernovae.Lunar samples retain valuable information from these events,via detectable long-lived“fingerprint”radionuclides such as^(60)Fe.In this work,we stepped up the development of an accelerator mass spectrometry(AMS)method for detecting^(60)Fe using the HI-13tandem accelerator at the China Institute of Atomic Energy(CIAE).Since interferences could not be sufficiently removed solely with the existing magnetic systems of the tandem accelerator and the following Q3D magnetic spectrograph,a Wien filter with a maximum voltage of±60 kV and a maximum magnetic field of 0.3 T was installed after the accelerator magnetic systems to lower the detection background for the low abundance nuclide^(60)Fe.A 1μm thick Si_(3)N_(4) foil was installed in front of the Q3D as an energy degrader.For particle detection,a multi-anode gas ionization chamber was mounted at the center of the focal plane of the spectrograph.Finally,an^(60)Fe sample with an abundance of 1.125×10^(-10)was used to test the new AMS system.These results indicate that^(60)Fe can be clearly distinguished from the isobar^(60)Ni.The sensitivity was assessed to be better than 4.3×10^(-14)based on blank sample measurements lasting 5.8 h,and the sensitivity could,in principle,be expected to be approximately 2.5×10^(-15)when the data were accumulated for 100 h,which is feasible for future lunar sample measurements because the main contaminants were sufficiently separated.展开更多
This paper proposes a new numerical simulation method for analyzing the parametric vibration of stay cables based on the theory of nonlinear dynamic response of structures under the asynchronous support excitation. Th...This paper proposes a new numerical simulation method for analyzing the parametric vibration of stay cables based on the theory of nonlinear dynamic response of structures under the asynchronous support excitation. The effects of important pa- rameters related to parametric vibration of cables, i.e., characteristics of structure, excitation frequency, excitation amplitude, damping effect of the air and the viscous damping coefficient of the cables, were investigated by using the proposed method for the cables with significant length difference as examples. The analysis results show that nonlinear finite element method is a powerful technique in analyzing the parametric vibration of cables, the behavior of parametric vibration of the two cables with different Irvine parameters has similar properties, the amplitudes of parametric vibration of cables are related to the frequency and amplitude of harmonic support excitations and the effect of distributed viscous damping on parametric vibration of the cables is very small.展开更多
Through the experience of being stationed on the USS Mercy hospital ship(T-AH19) and a preliminary comprehension of the personnel and material arrangements,processing and functional formats,and the multi-platform cont...Through the experience of being stationed on the USS Mercy hospital ship(T-AH19) and a preliminary comprehension of the personnel and material arrangements,processing and functional formats,and the multi-platform contributions of US Navy hospital ships,we briefly introduce the characteristics of US hospital ships regarding medical support,emergency rescue exercises,communications and training,international humanitarian aid,etc.We discuss the function and responsibility of Chinese hospital ships,focusing on the investigation of the construction mode and positioning in the navy.展开更多
A novel small band-gap conjugated polymer - poly [(3-acetylpyrrole-2,5-diyl)(4-dimethylaminobenzyliene)(3-acetylpyrrolequinodimethane-2,5-diyl)] (PAPDMABE) - and its precursor were synthesized by a simple method and c...A novel small band-gap conjugated polymer - poly [(3-acetylpyrrole-2,5-diyl)(4-dimethylaminobenzyliene)(3-acetylpyrrolequinodimethane-2,5-diyl)] (PAPDMABE) - and its precursor were synthesized by a simple method and characterized by H-1-NMR, FT-IR, TGA and UV-VIS. The polymer can be dissolved in strong polar solvents such as DMSO, DMF or NMP. The band-gap energy of PAPDMABE, was found to be 0.95 eV. The conductivity of doped products with iodine falls in the range of a semiconductor.展开更多
Chirality,the property that an object cannot coincide with its mirror image arising from lack of mirror symmetry,is ubiquitous in nature at various length scales.The physical and chemical properties are strongly relat...Chirality,the property that an object cannot coincide with its mirror image arising from lack of mirror symmetry,is ubiquitous in nature at various length scales.The physical and chemical properties are strongly related to the nature of chiral complexes,playing a significant role in various fields such as photonics,biochemistry,medicine and catalysis.In particular,the recent flexible design of chiral metal nanostructures offers one platform for deeply understanding the origin of chirality and one roadmap for the precise construction of chiral nanomaterials directed by the applications.Herein,we summarize the different geometries and classical synthetic approaches to chiral noble metal nanomaterials.Moreover,chiroptical properties and potential applications of chiral metal nanostructures are discussed as well.Finally,the opportunities and challenges toward the synthesis and application of chiral metal nanostructures are proposed.展开更多
Artificial synapses and neurons are crucial milestones for neuromorphic computing hardware,and memristors with resistive and threshold switching characteristics are regarded as the most promising candidates for the co...Artificial synapses and neurons are crucial milestones for neuromorphic computing hardware,and memristors with resistive and threshold switching characteristics are regarded as the most promising candidates for the construction of hardware neural networks.However,most of the memristors can only operate in one mode,that is,resistive switching or threshold switching,and distinct memristors are required to construct fully memristive neuromorphic computing hardware,making it more complex for the fabrication and integration of the hardware.Herein,we propose a flexible dual-mode memristor array based on core–shell CsPbBr3@graphdiyne nanocrystals,which features a 100%transition yield,small cycle-to-cycle and device-to-device variability,excellent flexibility,and environmental stability.Based on this dual-mode memristor,homo-material-based fully memristive neuromorphic computing hardware—a power-free artificial nociceptive signal processing system and a spiking neural network—are constructed for the first time.Our dual-mode memristors greatly simplify the fabrication and integration of fully memristive neuromorphic systems.展开更多
Pediatric acute hyperextension spinal cord injury(SCI)named as PAHSCI by us,is a special type of thoracolumbar SCI without radiographic abnormality and highly related to back-bend in dance training,which has been incr...Pediatric acute hyperextension spinal cord injury(SCI)named as PAHSCI by us,is a special type of thoracolumbar SCI without radiographic abnormality and highly related to back-bend in dance training,which has been increasingly reported.At present,it has become the leading cause of SCI in children,and brings a heavy social and economic burden.Both domestic and foreign academic institutions and dance education organizations lack a correct understanding of PAHSCI and relevant standards,specifications or guidelines.In order to provide standardized guidance,the expert team formulated this guideline based on the principles of science and practicability,starting from the diagnosis,differential diagnosis,etiology,admission evaluation,treatment,complications and prevention.This guideline puts forward 23 recommendations for 14 related issues.展开更多
Background： Many clinical studies over the past decade have indicated positive outcomes for patients treated with Dynesys dynamic stabilization for lumbar degenerative disease. However, long-term outcomes of Dynesys ...Background： Many clinical studies over the past decade have indicated positive outcomes for patients treated with Dynesys dynamic stabilization for lumbar degenerative disease. However, long-term outcomes of Dynesys for lumbar spinal stenosis are rarely reported. The aim of this study was to analyze the long-term clinical and radiologic outcomes for patients with lumbar spinal stenosis treated with Dynesys stabilization. Methods： Thirty-eight patients with lumbar spinal stenosis were treated with Dynesys stabilization from July 2008 to March 2010. The minimal duration of follow-up was 72 months. The patients were divided into stenosis and spondylolisthesis groups according to degenerative spondylolisthesis. Clinical outcomes were evaluated using the Oswestry Disability Index （ODI） and visual analog scale （VAS）. Radiographic evaluations included range of motion （ROM） and the disc heights of stabilized segments and the upper adjacent segments. We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration （ASD）. Results： There were 23 patients in stenosis group and 15 patients in spondylolisthesis group. The ODl scores were significantly improved at the final follow-up evaluation, as compared to the baseline values （ 16.1± 5.7 vs. 57.2 ± 14.2, t = 61.4 l, P 〈 0.01 ）. The VA S scores for back and leg pain were significantly improved from 4.82 ±0.89 and 4.04 ± 0.82 preoperatively to 0.93± 0.61 and 0.54 ± 0.51 postoperatively （t = 6.59, P 〈 0.01, and t = 5.91, P 〈 0.01, respectively）. There were no differences between the two groups with respect to VAS and ODI scores. The ROM of stabilized segments decreased significantly from 7.8°± 2.4° to 4.5° ± 1.5° （t = 7.18, P 〈 0.05）, while the upper adjacent segments increased significantly from 8.3° ± 2.4° to 10.4° ± 2.4° （t = 2.87, P = 0.01）. The change in disc height of stabilized segments was not significant （11.9 ±2.1 preoperatively vs. 12.5 ± 1.5 postoperatively, t = 1.43, P = 0.15）, whereas the decrease in disc height of the upper adjacent segments was significant （12.5 ±2.0 preopcratively vs. 11.0 ± 1.7 postoperatively, t = 2.94, P = 0.01 ）. The occurrence of radiographic and symptomatic ASD was 16% （6/38） and 3% （1/38）, respectively. Conclusions： Decompression and Dynesys stabilization for lumbar stenosis with or without spondylolisthesis showed good long-term clinical and radiographic results. Lumbar stenosis with or without Grade I spondylolisthesis, particularly in patients 〈60 years of age with mild-to-moderate lumbar disc degeneration, would be one of the main indications for the Dynesys system.展开更多
The electrochemical CO_(2) reduction(ECR)into value-added products presents an appealing approach to mitigate CO_(2) emission caused by excess consumption of fossil fuels.To obtain high catalytic activity and selectiv...The electrochemical CO_(2) reduction(ECR)into value-added products presents an appealing approach to mitigate CO_(2) emission caused by excess consumption of fossil fuels.To obtain high catalytic activity and selectivity toward target product in ECR,designing and developing a stable and efficient electrocatalyst is of significant importance.To date,metal nanomaterials have been widely applied as electrocatalysts for ECR due to their unique physicochemical properties.The structural modulation of metal nanomaterials is an attractive strategy to improve the catalytic performance.In this review,the recent progress of structural modulation,including size,facet,grain boundary,composition,interface,ligand modification,and crystal phase,is systematically summarized from both theoretical and experimental aspects.Finally,the opportunities and perspectives of structural modulation of metal nanomaterials for ECR are proposed.展开更多
Single-atom catalysts(SACS) have obtained a great deal of attention in many catalytic fields due to the high atom utilization efficiency and high catalytic activity.Recently,great achievements on S ACs have been made ...Single-atom catalysts(SACS) have obtained a great deal of attention in many catalytic fields due to the high atom utilization efficiency and high catalytic activity.Recently,great achievements on S ACs have been made for thermocatalysis,electrocatalysis,and photocatalysis which play an important role in obtaining value-added products.However,it remains a great challenge to fabricate S ACs with high metal loading and investigate their reaction mechanisms.Therefore,it is necessary to highlight the recent development of S ACs in these fields to guide future research.In this review,we overviewed the thermocatalysis applications of SACs in CO oxidation,preferential oxidation of CO,water-gas shift reaction,methane conversion,methanol steam reforming,aqueous-phase reforming of methanol,hydrogenation of alkynes and dienes,hydrogenation of CO,and hydrogenation of substituted nitroarenes.Moreover,the oxygen reduction reaction(ORR),hydrogen evolution reaction(HER),oxygen evolution reaction(OER),CO2 reduction reaction(CO2 RR),and N2 reduction reaction(N2 RR) for photocatalytic and electrocatalytic fields were also overviewed.Lastly,the opportunities and challenges of SACs were pointed out.展开更多
Graphdiyne(GDY)is emerging as a promising material for various applications owing to its unique structure and fascinating properties.However,the application of GDY in electronics and optoelectronics are still in its i...Graphdiyne(GDY)is emerging as a promising material for various applications owing to its unique structure and fascinating properties.However,the application of GDY in electronics and optoelectronics are still in its infancy,primarily owing to the huge challenge in the synthesis of large-area and uniform GDY film for scalable applications.Here a modified van der Waals epitaxy strategy is proposed to synthesize wafer-scale GDY film with high uniformity and controllable thickness directly on graphene(Gr)surface,providing an ideal platform to construct large-scale GDY/Gr-based optoelectronic synapse array.Essential synaptic behaviors have been realized,and the linear and symmetric conductance-update characteristics facilitate the implementation of neuromorphic computing for image recognition with high accuracy and strong fault tolerance.Logic functions including“NAND”and“NOR”are integrated into the synapse which can be executed in an optical pathway.Moreover,a visible information sensing-memory-processing system is constructed to execute real-time image acquisition,in situ image memorization and distinction tasks,avoiding the time latency and energy consumption caused by data conversion and transmission in conventional visual systems.These results highlight the potential of GDY in applications of neuromorphic computing and artificial visual systems.展开更多
Despite the reactive facets play a vital role in designing highly efficient photocatalysts,it has long been a tremendous challenge to reveal the principle that reactive facets favor photocatalysis at the molecular lev...Despite the reactive facets play a vital role in designing highly efficient photocatalysts,it has long been a tremendous challenge to reveal the principle that reactive facets favor photocatalysis at the molecular level.In a recent work published in Nature catalysis,Lin et al.展开更多
Electrochemical carbon dioxide(CO_(2))reduction reaction(CO_(2)RR),powered by a renewable energy source,to valueadded chemicals and fuels is a promising solution to mitigate the ever-increasing CO_(2)emission and buil...Electrochemical carbon dioxide(CO_(2))reduction reaction(CO_(2)RR),powered by a renewable energy source,to valueadded chemicals and fuels is a promising solution to mitigate the ever-increasing CO_(2)emission and build carbon recycling systems[1-4].展开更多
We aimed to explore the associations between the age at which children undergo surgery for hypospadias and a range of social and clinical factors in a single center.Our aim was to promote the early surgical treatment ...We aimed to explore the associations between the age at which children undergo surgery for hypospadias and a range of social and clinical factors in a single center.Our aim was to promote the early surgical treatment of children with hypospadias.For a 6-year period,social and clinical data were collected from all children undergoing surgery to repair hypospadias in Children’s Hospital of Chongqing Medical University(Chongqing,China),located in southwest of China.We analyzed the correlations between age at surgery and a range of social and clinical factors.A total of 1611 eligible cases were recruited,with a mean age of 54.3 months and a median age of 42 months:234 cases(14.5%)were classified into a“timely operation”group,419(26.0%)cases into a“subtimely operation”group,and 958(59.5%)cases into a“delayed operation”group.According to multivariate regression analyses,the higher the regional economic level,the closer the urethral opening to the perineum,and the higher the educational level of the guardians was,the younger the children were when they underwent the initial surgery for hypospadias;this was also the case for families without other children.Our subgroup analysis showed that the primary educational level of the guardians was a risk factor for subtimely surgery in their children(odds ratio[OR]=1.52,95%confidence interval[CI]:1.08-2.15,P<0.05).A lower regional economic level(OR=1.87,95%CI:1.26-2.78,P<0.01),a lower educational level of the guardians(OR=3.84,95%CI:2.31-6.41,P<0.01),and an anterior-segment urethral opening(OR_(1)[vs middle hypospadias]=2.07,95%CI:1.42-3.03;0R_(2)[vs posterior hypospadias]=2.63,95%CI:1.75-3.95;P<0.01)were all risk factors for delayed surgery in children.展开更多
Electrocatalytic CO_(2) reduction reaction(CO_(2) RR)has been regarded as a highly effective strategy to produce valuable fuels and feedstocks,contributing to achieving a carbon–neutral cycle and dramatically mitigat...Electrocatalytic CO_(2) reduction reaction(CO_(2) RR)has been regarded as a highly effective strategy to produce valuable fuels and feedstocks,contributing to achieving a carbon–neutral cycle and dramatically mitigating CO_(2) emission[1–6].Generally,alkaline or near-neutral solution,such as KOH or KHCO3aqueous solution,is employed as elec-trolytes for CO_(2) RR owing to higher solubility of CO_(2) in electrolytes[1,7–10].展开更多
Fluorinated polymers are important materials that are widely used in many areas as taking the advantage of inertness to chemical corrosion,prominent weather resista nee,low flammability,and good thermal stability.Poly...Fluorinated polymers are important materials that are widely used in many areas as taking the advantage of inertness to chemical corrosion,prominent weather resista nee,low flammability,and good thermal stability.Poly(vinylidene fluoride)(PVDF)based fluoropolymers is the most commontype of commercial fluoropolymer especially used as dielectric materials.However,there are always some shortcomings in practical applications,so it is necessary to modify PVDF-based fluoropolymers for better application.Controlled/living radical polymerization(CRP)and related techniques have become a powerful approach to tailoring the chemical and physical properties of materials and have given rise to great advances in modification of PVDF-based fluoropolymers.展开更多
To the Editor： Percutaneous endoscopic lumbar discectomy （PELD） becomes increasingly popular among spine surgeries in recent years. PELD is one of the minimally invasive spine surgeries with significant advantages ...To the Editor： Percutaneous endoscopic lumbar discectomy （PELD） becomes increasingly popular among spine surgeries in recent years. PELD is one of the minimally invasive spine surgeries with significant advantages including small incision, less muscle stripping, and enhanced postoperative recovery.展开更多
The post-functionalization of gold nanoclusters with organic molecules into organic-inorganic hybrid functional materials is an efficient approach to develop multifunctional materials.By introducing 1-pyrenamine and 3...The post-functionalization of gold nanoclusters with organic molecules into organic-inorganic hybrid functional materials is an efficient approach to develop multifunctional materials.By introducing 1-pyrenamine and 3-aminofluoranthene into[O(AuPPh_(3))_(3)][BF_(4)]with a covalent bond,two novel organoimido functionalized trinuclear gold nanoclusters[C_(16)H_(9)N(AuPPh_(3))_(3)][BF_(4)](Au_(3)-P)and[C_(6)H_(4)-C_(10)H_(5)N(AuPPh_(3))_(3)][BF_(4)](Au_(3)-F)have been successfully obtained.Their structures have been determined by electrospray ionization mass spectroscopy(ESI-MS)and single-crystal X-ray diffraction(SC-XRD),and the photoluminescence properties have been investigated from both experimental and theoretical aspects.It is found that the lowest-energy electronic transitions in the ultraviolet-visible(UV-Vis)absorption spectra of Au_(3)-P(403 nm)and Au_(3)-F(425 nm)exhibit a slight bathochromic shift compared to the corresponding transitions in the spectra of 1-pyrenamine and 3-aminofluoranthene,respectively.In addition,the dichloromethane solutions of Au_(3)-P and Au_(3)-F complexes clearly display blue and yellowish-green fluorescence,respectively.These results will help to design and prepare organic-inorganic nanocluster hybrid luminescent materials for potential applications in(bio)sensors,bioimaging and optoelectronic devices.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12125509,12222514,11961141003,and 12005304)National Key Research and Development Project(No.2022YFA1602301)+1 种基金CAST Young Talent Support Planthe CNNC Science Fund for Talented Young Scholars Continuous support for basic scientific research projects。
文摘The Moon provides a unique environment for investigating nearby astrophysical events such as supernovae.Lunar samples retain valuable information from these events,via detectable long-lived“fingerprint”radionuclides such as^(60)Fe.In this work,we stepped up the development of an accelerator mass spectrometry(AMS)method for detecting^(60)Fe using the HI-13tandem accelerator at the China Institute of Atomic Energy(CIAE).Since interferences could not be sufficiently removed solely with the existing magnetic systems of the tandem accelerator and the following Q3D magnetic spectrograph,a Wien filter with a maximum voltage of±60 kV and a maximum magnetic field of 0.3 T was installed after the accelerator magnetic systems to lower the detection background for the low abundance nuclide^(60)Fe.A 1μm thick Si_(3)N_(4) foil was installed in front of the Q3D as an energy degrader.For particle detection,a multi-anode gas ionization chamber was mounted at the center of the focal plane of the spectrograph.Finally,an^(60)Fe sample with an abundance of 1.125×10^(-10)was used to test the new AMS system.These results indicate that^(60)Fe can be clearly distinguished from the isobar^(60)Ni.The sensitivity was assessed to be better than 4.3×10^(-14)based on blank sample measurements lasting 5.8 h,and the sensitivity could,in principle,be expected to be approximately 2.5×10^(-15)when the data were accumulated for 100 h,which is feasible for future lunar sample measurements because the main contaminants were sufficiently separated.
基金Project (No. 50578141) supported by the National Natural Science Foundation of China
文摘This paper proposes a new numerical simulation method for analyzing the parametric vibration of stay cables based on the theory of nonlinear dynamic response of structures under the asynchronous support excitation. The effects of important pa- rameters related to parametric vibration of cables, i.e., characteristics of structure, excitation frequency, excitation amplitude, damping effect of the air and the viscous damping coefficient of the cables, were investigated by using the proposed method for the cables with significant length difference as examples. The analysis results show that nonlinear finite element method is a powerful technique in analyzing the parametric vibration of cables, the behavior of parametric vibration of the two cables with different Irvine parameters has similar properties, the amplitudes of parametric vibration of cables are related to the frequency and amplitude of harmonic support excitations and the effect of distributed viscous damping on parametric vibration of the cables is very small.
文摘Through the experience of being stationed on the USS Mercy hospital ship(T-AH19) and a preliminary comprehension of the personnel and material arrangements,processing and functional formats,and the multi-platform contributions of US Navy hospital ships,we briefly introduce the characteristics of US hospital ships regarding medical support,emergency rescue exercises,communications and training,international humanitarian aid,etc.We discuss the function and responsibility of Chinese hospital ships,focusing on the investigation of the construction mode and positioning in the navy.
文摘A novel small band-gap conjugated polymer - poly [(3-acetylpyrrole-2,5-diyl)(4-dimethylaminobenzyliene)(3-acetylpyrrolequinodimethane-2,5-diyl)] (PAPDMABE) - and its precursor were synthesized by a simple method and characterized by H-1-NMR, FT-IR, TGA and UV-VIS. The polymer can be dissolved in strong polar solvents such as DMSO, DMF or NMP. The band-gap energy of PAPDMABE, was found to be 0.95 eV. The conductivity of doped products with iodine falls in the range of a semiconductor.
基金financially supported by the National Natural Science Foundation of China(Nos.22071172,21902148,12205165,50835002 and 51105102)。
文摘Chirality,the property that an object cannot coincide with its mirror image arising from lack of mirror symmetry,is ubiquitous in nature at various length scales.The physical and chemical properties are strongly related to the nature of chiral complexes,playing a significant role in various fields such as photonics,biochemistry,medicine and catalysis.In particular,the recent flexible design of chiral metal nanostructures offers one platform for deeply understanding the origin of chirality and one roadmap for the precise construction of chiral nanomaterials directed by the applications.Herein,we summarize the different geometries and classical synthetic approaches to chiral noble metal nanomaterials.Moreover,chiroptical properties and potential applications of chiral metal nanostructures are discussed as well.Finally,the opportunities and challenges toward the synthesis and application of chiral metal nanostructures are proposed.
基金Natural Science Foundation of Tianjin City,Grant/Award Number:19JCYBJC17300National Natural Science Foundation of China,Grant/Award Numbers:21790052,51802220。
文摘Artificial synapses and neurons are crucial milestones for neuromorphic computing hardware,and memristors with resistive and threshold switching characteristics are regarded as the most promising candidates for the construction of hardware neural networks.However,most of the memristors can only operate in one mode,that is,resistive switching or threshold switching,and distinct memristors are required to construct fully memristive neuromorphic computing hardware,making it more complex for the fabrication and integration of the hardware.Herein,we propose a flexible dual-mode memristor array based on core–shell CsPbBr3@graphdiyne nanocrystals,which features a 100%transition yield,small cycle-to-cycle and device-to-device variability,excellent flexibility,and environmental stability.Based on this dual-mode memristor,homo-material-based fully memristive neuromorphic computing hardware—a power-free artificial nociceptive signal processing system and a spiking neural network—are constructed for the first time.Our dual-mode memristors greatly simplify the fabrication and integration of fully memristive neuromorphic systems.
基金National Natural Science Foundation of China(No.82072446 and 81873999)International Science&Technology Cooperation Program of China(No.2013DFG32690)Key R&D Program of Hubei Province(2020BCB050)。
文摘Pediatric acute hyperextension spinal cord injury(SCI)named as PAHSCI by us,is a special type of thoracolumbar SCI without radiographic abnormality and highly related to back-bend in dance training,which has been increasingly reported.At present,it has become the leading cause of SCI in children,and brings a heavy social and economic burden.Both domestic and foreign academic institutions and dance education organizations lack a correct understanding of PAHSCI and relevant standards,specifications or guidelines.In order to provide standardized guidance,the expert team formulated this guideline based on the principles of science and practicability,starting from the diagnosis,differential diagnosis,etiology,admission evaluation,treatment,complications and prevention.This guideline puts forward 23 recommendations for 14 related issues.
文摘Background： Many clinical studies over the past decade have indicated positive outcomes for patients treated with Dynesys dynamic stabilization for lumbar degenerative disease. However, long-term outcomes of Dynesys for lumbar spinal stenosis are rarely reported. The aim of this study was to analyze the long-term clinical and radiologic outcomes for patients with lumbar spinal stenosis treated with Dynesys stabilization. Methods： Thirty-eight patients with lumbar spinal stenosis were treated with Dynesys stabilization from July 2008 to March 2010. The minimal duration of follow-up was 72 months. The patients were divided into stenosis and spondylolisthesis groups according to degenerative spondylolisthesis. Clinical outcomes were evaluated using the Oswestry Disability Index （ODI） and visual analog scale （VAS）. Radiographic evaluations included range of motion （ROM） and the disc heights of stabilized segments and the upper adjacent segments. We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration （ASD）. Results： There were 23 patients in stenosis group and 15 patients in spondylolisthesis group. The ODl scores were significantly improved at the final follow-up evaluation, as compared to the baseline values （ 16.1± 5.7 vs. 57.2 ± 14.2, t = 61.4 l, P 〈 0.01 ）. The VA S scores for back and leg pain were significantly improved from 4.82 ±0.89 and 4.04 ± 0.82 preoperatively to 0.93± 0.61 and 0.54 ± 0.51 postoperatively （t = 6.59, P 〈 0.01, and t = 5.91, P 〈 0.01, respectively）. There were no differences between the two groups with respect to VAS and ODI scores. The ROM of stabilized segments decreased significantly from 7.8°± 2.4° to 4.5° ± 1.5° （t = 7.18, P 〈 0.05）, while the upper adjacent segments increased significantly from 8.3° ± 2.4° to 10.4° ± 2.4° （t = 2.87, P = 0.01）. The change in disc height of stabilized segments was not significant （11.9 ±2.1 preoperatively vs. 12.5 ± 1.5 postoperatively, t = 1.43, P = 0.15）, whereas the decrease in disc height of the upper adjacent segments was significant （12.5 ±2.0 preopcratively vs. 11.0 ± 1.7 postoperatively, t = 2.94, P = 0.01 ）. The occurrence of radiographic and symptomatic ASD was 16% （6/38） and 3% （1/38）, respectively. Conclusions： Decompression and Dynesys stabilization for lumbar stenosis with or without spondylolisthesis showed good long-term clinical and radiographic results. Lumbar stenosis with or without Grade I spondylolisthesis, particularly in patients 〈60 years of age with mild-to-moderate lumbar disc degeneration, would be one of the main indications for the Dynesys system.
基金financially supported by the National Key R&D Program(N os.2017 YF A0204503 and 2016YFB0401100)the National Natural Science Foundation of China(Nos.91833306,21875158,51633006 and 51703159)。
文摘The electrochemical CO_(2) reduction(ECR)into value-added products presents an appealing approach to mitigate CO_(2) emission caused by excess consumption of fossil fuels.To obtain high catalytic activity and selectivity toward target product in ECR,designing and developing a stable and efficient electrocatalyst is of significant importance.To date,metal nanomaterials have been widely applied as electrocatalysts for ECR due to their unique physicochemical properties.The structural modulation of metal nanomaterials is an attractive strategy to improve the catalytic performance.In this review,the recent progress of structural modulation,including size,facet,grain boundary,composition,interface,ligand modification,and crystal phase,is systematically summarized from both theoretical and experimental aspects.Finally,the opportunities and perspectives of structural modulation of metal nanomaterials for ECR are proposed.
基金financially supported by the National Natural Science Foundation of China(Nos.11675051,51302079,51702138,51702297,51633006,51725304,51733004,51703159,and 51903186)the Natural Science Foundation of Hunan Province(No.2017JJ1008)+1 种基金the Key Research and Development Program of Hunan Province of China(No.2018GK2031)the Ministry of Science and Technology of China(Nos.2017YFA0204503 and 2016YFB0401100)。
文摘Single-atom catalysts(SACS) have obtained a great deal of attention in many catalytic fields due to the high atom utilization efficiency and high catalytic activity.Recently,great achievements on S ACs have been made for thermocatalysis,electrocatalysis,and photocatalysis which play an important role in obtaining value-added products.However,it remains a great challenge to fabricate S ACs with high metal loading and investigate their reaction mechanisms.Therefore,it is necessary to highlight the recent development of S ACs in these fields to guide future research.In this review,we overviewed the thermocatalysis applications of SACs in CO oxidation,preferential oxidation of CO,water-gas shift reaction,methane conversion,methanol steam reforming,aqueous-phase reforming of methanol,hydrogenation of alkynes and dienes,hydrogenation of CO,and hydrogenation of substituted nitroarenes.Moreover,the oxygen reduction reaction(ORR),hydrogen evolution reaction(HER),oxygen evolution reaction(OER),CO2 reduction reaction(CO2 RR),and N2 reduction reaction(N2 RR) for photocatalytic and electrocatalytic fields were also overviewed.Lastly,the opportunities and challenges of SACs were pointed out.
基金This work was supported by the National Natural Science Foundation of China(Nos.21790052 and 51802220)Natural Science Foundation of Tianjin City(No.19JCYBJC17300).
文摘Graphdiyne(GDY)is emerging as a promising material for various applications owing to its unique structure and fascinating properties.However,the application of GDY in electronics and optoelectronics are still in its infancy,primarily owing to the huge challenge in the synthesis of large-area and uniform GDY film for scalable applications.Here a modified van der Waals epitaxy strategy is proposed to synthesize wafer-scale GDY film with high uniformity and controllable thickness directly on graphene(Gr)surface,providing an ideal platform to construct large-scale GDY/Gr-based optoelectronic synapse array.Essential synaptic behaviors have been realized,and the linear and symmetric conductance-update characteristics facilitate the implementation of neuromorphic computing for image recognition with high accuracy and strong fault tolerance.Logic functions including“NAND”and“NOR”are integrated into the synapse which can be executed in an optical pathway.Moreover,a visible information sensing-memory-processing system is constructed to execute real-time image acquisition,in situ image memorization and distinction tasks,avoiding the time latency and energy consumption caused by data conversion and transmission in conventional visual systems.These results highlight the potential of GDY in applications of neuromorphic computing and artificial visual systems.
文摘Despite the reactive facets play a vital role in designing highly efficient photocatalysts,it has long been a tremendous challenge to reveal the principle that reactive facets favor photocatalysis at the molecular level.In a recent work published in Nature catalysis,Lin et al.
基金financially supported by the National Natural Science Foundation of China (No.22071172)
文摘Electrochemical carbon dioxide(CO_(2))reduction reaction(CO_(2)RR),powered by a renewable energy source,to valueadded chemicals and fuels is a promising solution to mitigate the ever-increasing CO_(2)emission and build carbon recycling systems[1-4].
基金the National Natural Science Foundation of China(No.81970571)。
文摘We aimed to explore the associations between the age at which children undergo surgery for hypospadias and a range of social and clinical factors in a single center.Our aim was to promote the early surgical treatment of children with hypospadias.For a 6-year period,social and clinical data were collected from all children undergoing surgery to repair hypospadias in Children’s Hospital of Chongqing Medical University(Chongqing,China),located in southwest of China.We analyzed the correlations between age at surgery and a range of social and clinical factors.A total of 1611 eligible cases were recruited,with a mean age of 54.3 months and a median age of 42 months:234 cases(14.5%)were classified into a“timely operation”group,419(26.0%)cases into a“subtimely operation”group,and 958(59.5%)cases into a“delayed operation”group.According to multivariate regression analyses,the higher the regional economic level,the closer the urethral opening to the perineum,and the higher the educational level of the guardians was,the younger the children were when they underwent the initial surgery for hypospadias;this was also the case for families without other children.Our subgroup analysis showed that the primary educational level of the guardians was a risk factor for subtimely surgery in their children(odds ratio[OR]=1.52,95%confidence interval[CI]:1.08-2.15,P<0.05).A lower regional economic level(OR=1.87,95%CI:1.26-2.78,P<0.01),a lower educational level of the guardians(OR=3.84,95%CI:2.31-6.41,P<0.01),and an anterior-segment urethral opening(OR_(1)[vs middle hypospadias]=2.07,95%CI:1.42-3.03;0R_(2)[vs posterior hypospadias]=2.63,95%CI:1.75-3.95;P<0.01)were all risk factors for delayed surgery in children.
文摘Electrocatalytic CO_(2) reduction reaction(CO_(2) RR)has been regarded as a highly effective strategy to produce valuable fuels and feedstocks,contributing to achieving a carbon–neutral cycle and dramatically mitigating CO_(2) emission[1–6].Generally,alkaline or near-neutral solution,such as KOH or KHCO3aqueous solution,is employed as elec-trolytes for CO_(2) RR owing to higher solubility of CO_(2) in electrolytes[1,7–10].
基金This work was financially supported by the National Natural Science Foundation of China(Nos.92066204,52003214,51773166 and 51603167)China Postdoctoral Science Foundation Funded Project(Nos.2019M663699 and 2020T130507)+3 种基金Key Laboratory Construction Program of Xi'an Municipal Bureau of Science and Technology(No.201805056ZD7CG40)Natural Science Foundation of Jiangsu Province(No.BK2020245)Suzhou Science and Technology Project(No.SYG202028)the Fundamental Research Funds for the Central Universities(No.xzy012020035).
文摘Fluorinated polymers are important materials that are widely used in many areas as taking the advantage of inertness to chemical corrosion,prominent weather resista nee,low flammability,and good thermal stability.Poly(vinylidene fluoride)(PVDF)based fluoropolymers is the most commontype of commercial fluoropolymer especially used as dielectric materials.However,there are always some shortcomings in practical applications,so it is necessary to modify PVDF-based fluoropolymers for better application.Controlled/living radical polymerization(CRP)and related techniques have become a powerful approach to tailoring the chemical and physical properties of materials and have given rise to great advances in modification of PVDF-based fluoropolymers.
文摘To the Editor： Percutaneous endoscopic lumbar discectomy （PELD） becomes increasingly popular among spine surgeries in recent years. PELD is one of the minimally invasive spine surgeries with significant advantages including small incision, less muscle stripping, and enhanced postoperative recovery.
基金financially supported by the foundation of Key Laboratory of Ethnomedicine(Minzu University of China),Ministry of Education(No.KLEM-ZZ201804)the Young Teachers’Scientific Research Ability Promotion Program of Minzu University of China(No.2018QNPY57)Beijing Municipal Natural Science Foundation(No.2154049)。
文摘The post-functionalization of gold nanoclusters with organic molecules into organic-inorganic hybrid functional materials is an efficient approach to develop multifunctional materials.By introducing 1-pyrenamine and 3-aminofluoranthene into[O(AuPPh_(3))_(3)][BF_(4)]with a covalent bond,two novel organoimido functionalized trinuclear gold nanoclusters[C_(16)H_(9)N(AuPPh_(3))_(3)][BF_(4)](Au_(3)-P)and[C_(6)H_(4)-C_(10)H_(5)N(AuPPh_(3))_(3)][BF_(4)](Au_(3)-F)have been successfully obtained.Their structures have been determined by electrospray ionization mass spectroscopy(ESI-MS)and single-crystal X-ray diffraction(SC-XRD),and the photoluminescence properties have been investigated from both experimental and theoretical aspects.It is found that the lowest-energy electronic transitions in the ultraviolet-visible(UV-Vis)absorption spectra of Au_(3)-P(403 nm)and Au_(3)-F(425 nm)exhibit a slight bathochromic shift compared to the corresponding transitions in the spectra of 1-pyrenamine and 3-aminofluoranthene,respectively.In addition,the dichloromethane solutions of Au_(3)-P and Au_(3)-F complexes clearly display blue and yellowish-green fluorescence,respectively.These results will help to design and prepare organic-inorganic nanocluster hybrid luminescent materials for potential applications in(bio)sensors,bioimaging and optoelectronic devices.
