In this paper,we reconstruct strongly-decaying block sparse signals by the block generalized orthogonal matching pursuit(BgOMP)algorithm in the l2-bounded noise case.Under some restraints on the minimum magnitude of t...In this paper,we reconstruct strongly-decaying block sparse signals by the block generalized orthogonal matching pursuit(BgOMP)algorithm in the l2-bounded noise case.Under some restraints on the minimum magnitude of the nonzero elements of the strongly-decaying block sparse signal,if the sensing matrix satisfies the the block restricted isometry property(block-RIP),then arbitrary strongly-decaying block sparse signals can be accurately and steadily reconstructed by the BgOMP algorithm in iterations.Furthermore,we conjecture that this condition is sharp.展开更多
In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is ...In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is also affected by the block length.Therefore,it is crucial to balance the transmission performance and blockchain performance of blockchain communication systems,especially in wireless environments involving UAVs.This paper investigates a secure transmission scheme for blocks in blockchain-based UAV communication systems to prevent the information contained in blocks from being completely eavesdropped during transmission.In our scheme,using a friendly jamming UAV to emit jamming signals diminishes the quality of the eavesdropping channel,thus enhancing the communication security performance of the source UAV.Under the constraints of maneuverability and transmission power of the UAV,the joint design of UAV trajectories,transmission power,and block length are proposed to maximize the average minimum secrecy rate(AMSR).Since the optimization problem is non-convex and difficult to solve directly,we first decompose the optimization problem into subproblems of trajectory optimization,transmission power optimization,and block length optimization.Then,based on firstorder approximation techniques,these subproblems are reformulated as convex optimization problems.Finally,we utilize an alternating iteration algorithm based on the successive convex approximation(SCA)technique to solve these subproblems iteratively.The simulation results demonstrate that our proposed scheme can achieve secure transmission for blocks while maintaining the performance of the blockchain.展开更多
A number of publications have claimed that Mobitz type Ⅱ atrioventricular block(AVB)may occur during sleep.None of the reports defined type Ⅱ AVB and representative electrocardiograms were either misinterpreted or m...A number of publications have claimed that Mobitz type Ⅱ atrioventricular block(AVB)may occur during sleep.None of the reports defined type Ⅱ AVB and representative electrocardiograms were either misinterpreted or missing.Relatively benign Wenckebach type Ⅰ AVB is often misdiagnosed as Mobitz type Ⅱ which is an indication for a pacemaker.Review of the published reports indicates that Mobitz type II AVB does not occur during sleep when it is absent in the awake state.Conclusion:There is no proof that sleep is associated with Mobitz type Ⅱ AVB.展开更多
Blockchain technology has witnessed a burgeoning integration into diverse realms of economic and societal development.Nevertheless,scalability challenges,characterized by diminished broadcast efficiency,heightened com...Blockchain technology has witnessed a burgeoning integration into diverse realms of economic and societal development.Nevertheless,scalability challenges,characterized by diminished broadcast efficiency,heightened communication overhead,and escalated storage costs,have significantly constrained the broad-scale application of blockchain.This paper introduces a novel Encode-and CRT-based Scalability Scheme(ECSS),meticulously refined to enhance both block broadcasting and storage.Primarily,ECSS categorizes nodes into distinct domains,thereby reducing the network diameter and augmenting transmission efficiency.Secondly,ECSS streamlines block transmission through a compact block protocol and robust RS coding,which not only reduces the size of broadcasted blocks but also ensures transmission reliability.Finally,ECSS utilizes the Chinese remainder theorem,designating the block body as the compression target and mapping it to multiple modules to achieve efficient storage,thereby alleviating the storage burdens on nodes.To evaluate ECSS’s performance,we established an experimental platformand conducted comprehensive assessments.Empirical results demonstrate that ECSS attains superior network scalability and stability,reducing communication overhead by an impressive 72% and total storage costs by a substantial 63.6%.展开更多
BACKGROUND Awake fiberoptic nasotracheal intubation(AFNI)is the preferred airway ma-nagement strategy for patients with difficult airways.However,this procedure can cause significant physical and psychological distres...BACKGROUND Awake fiberoptic nasotracheal intubation(AFNI)is the preferred airway ma-nagement strategy for patients with difficult airways.However,this procedure can cause significant physical and psychological distress.This case report explores the application of a sphenopalatine ganglion(SPG)block as an alternative anal-gesic modality to mitigate the discomfort associated with AFNI.CASE SUMMARY A 63-year-old female with a history of right maxillary osteosarcoma underwent craniotomy for a suspected malignant brain lesion.The patient’s medical history included prior surgery,chemotherapy,and radiation therapy,resulting in signi-ficant jaw impairment and limited neck mobility.Considering the anticipated air-way challenges,AFNI was planned.A SPG block was performed under real-time ultrasound guidance,providing effective analgesia during nasotracheal intuba-tion.CONCLUSION The SPG block represents a promising analgesic approach in AFNI,offering po-tential benefits in alleviating pain involving the nasal and nasopharyngeal regions as well as improving patient cooperation.展开更多
BACKGROUND Anterior cutaneous nerve entrapment syndrome(ACNES)is a condition mani-festing with pain caused by strangulation of the anterior cutaneous branch of the lower intercostal nerves.This case report aims to pro...BACKGROUND Anterior cutaneous nerve entrapment syndrome(ACNES)is a condition mani-festing with pain caused by strangulation of the anterior cutaneous branch of the lower intercostal nerves.This case report aims to provide new insight into the selection of peripheral nerve blocks for the ACNES treatment.CASE SUMMARY A 66-year-old woman manifested ACNES after a robot-assisted distal gastrec-tomy.An ultrasound-guided rectal sheath block was effective for pain triggered by the port scar.However,the sudden severe pain,which radiated laterally from the previous site,remained.A transversus abdominis plane block was performed for the remaining pain and effectively relieved it.CONCLUSION In this case,the trocar port was inserted between the rectus and transverse abdominis muscles.The intercostal nerves might have been entrapped on both sides of the rectus and transversus abdominis muscles.Hence,rectus sheath and transverse abdominis plane blocks were required to achieve complete pain relief.To the best of our knowledge,this is the first report on use of a combination of rectus sheath and transverse abdominis plane blocks for pain relief in ACNES.展开更多
Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid...Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.展开更多
Cryogenic block streams consist of a stream of rocks superficially resembling a stream deposit but lacking a matrix, usually occurring on a valley or gully floor or on slopes that are less steep than the maximum angle...Cryogenic block streams consist of a stream of rocks superficially resembling a stream deposit but lacking a matrix, usually occurring on a valley or gully floor or on slopes that are less steep than the maximum angle of repose of coarse sediments. They are usually formed on perennially frozen ground, but can also occur as relict landforms. There are three main active kinds forming today, viz., Siberian and Tibetan dynamic rock streams and lag block streams. During their formation, the blocks in the active Siberian and Tibetan dynamic block streams move downslope at up to 1 rn/a. They are forming today on the Tibetan Plateau and in the more arid parts of south-central Siberia, although the processes involved in the movement are different. In the case of the Tibetan type, individual blocks slide downslope over the substrate in winter on an icy coating in areas of minimal winter precipitation. The Siberian type develops in areas of 15-80 cm of winter snow cover and an MAAT （mean annual air temperature） of-4 ~C to -17 ~C. The movement is due to creep of snow and ice and collapse of the blocks downslope during thawing. Lag block streams are formed by meltwater flowing over the surface of sediment consisting primarily of larger blocks with a limited amount of interstitial sediment. The erosion of the matrix is primarily in the spring in areas of higher winter precipitation on 10^-30~ slopes. The blocks remain stationary, but the interstitial sediment is washed out by strong seasonal flows of meltwater or rain to form an alluvial fan. The boulders undergo weathering and become more rounded in the process. Lag block streams can also develop without the presence of permafrost in areas with cold climates or glaciers. Block streams also occur as relict deposits in older deposits under various climatic regimes that are unsuitable for their formation today. An example of relict lag block streams with subangular to subrounded blocks occurs in gullies on the forested mountainsides at Felsen in Germany, and is the original ＂felsenmeer＂. Similar examples occur near Vitosha Mountain in Bulgaria. The ＂stone runs＂ in the Falkland Islands are examples of the more angular relict lag block streams. In both Tasmania and the Falkland Islands, they mask a more complex history, the underlying soils indicating periods of tropical and temperate soil formation resulting from weathering during and since the Tertiary Period. Block streams have also been reported from beneath cold-based glaciers in Sweden, and below till in Canada, and when ex- humed, can continue to develop.展开更多
Primary toppling usually occurs in layered rock slopes with large anti-dip angles.In this paper,the block toppling evolution was explored using a large-scale centrifuge system.Each block column in the layered model sl...Primary toppling usually occurs in layered rock slopes with large anti-dip angles.In this paper,the block toppling evolution was explored using a large-scale centrifuge system.Each block column in the layered model slope was made of cement mortar.Some artificial cracks perpendicular to the block column were prefabricated.Strain gages,displacement gages,and high-speed camera measurements were employed to monitor the deformation and failure processes of the model slope.The centrifuge test results show that the block toppling evolution can be divided into seven stages,i.e.layer compression,formation of major tensile crack,reverse bending of the block column,closure of major tensile crack,strong bending of the block column,formation of failure zone,and complete failure.Block toppling is characterized by sudden large deformation and occurs in stages.The wedge-shaped cracks in the model incline towards the slope.Experimental observations show that block toppling is mainly caused by bending failure rather than by shear failure.The tensile strength also plays a key factor in the evolution of block toppling.The simulation results from discrete element method(DEM)is in line with the testing results.Tensile stress exists at the backside of rock column during toppling deformation.Stress concentration results in the fragmented rock column and its degree is the most significant at the slope toe.展开更多
The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various industries.The conventional epoxy coating easily forms many intrinsic defects during the solidification proc...The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various industries.The conventional epoxy coating easily forms many intrinsic defects during the solidification process,which cannot provide sufficient protection.In the current study,we design a double-layer epoxy composite coating on Mg alloy with enhanced anti-corrosion/wear properties,via the spin-assisted assembly technique.The outer layer is functionalized graphene(FG)in waterborne epoxy resin(WEP)and the inner layer is Ce-based conversion(Ce)film.The FG sheets can be homogeneously dispersed within the epoxy matrix to fill the intrinsic defects and improve the barrier capability.The Ce film connects the outer layer with the substrate,showing the transition effect.The corrosion rate of Ce/WEP/FG composite coating is 2131 times lower than that of bare Mg alloy,and the wear rate is decreased by~90%.The improved corrosion resistance is attributed to the labyrinth effect(hindering the penetration of corrosive medium)and the obstruction of galvanic coupling behavior.The synergistic effect derived from the FG sheet and blocking layer exhibits great potential in realizing the improvement of multi-functional integration,which will open up a new avenue for the development of novel composite protection coatings of Mg alloys.展开更多
BACKGROUND Ultrasound guide technology,which can provide real-time visualization of the needle tip and tissues and avoid many adverse events,is widely used in mini-mally invasive therapy.However,the studies on ultraso...BACKGROUND Ultrasound guide technology,which can provide real-time visualization of the needle tip and tissues and avoid many adverse events,is widely used in mini-mally invasive therapy.However,the studies on ultrasound-guided Lateral recess block(LRB)are limited,this is probably because there is no recognized standard method for ultrasound scanning.This study aimed to evaluate the effect of ultrasound-guided LRB in patients with lateral recess stenosis(LRS).CASE SUMMARY A 65-year-old patient complained of low back pain accompanied occasionally by pain and numbness in the left lower limb.Physical examination showed ten-derness on the spinous process and paraspinal muscles from L1 to S1,extensor hallucis longus and tibialis anterior weakness(muscle strength:4-),and a positive straight leg raising test in the left lower limb(60°).Magnetic resonance imaging showed L4–L5 disc degeneration with left LRS and nerve root entrapment.Subsequently,the patient was diagnosed with LRS.This patient was treated with a novel ultrasound-guided LRB approach.The patient’s symptoms significantly improved without any complications at 1 wk postoperatively and at the 3-month follow-up.CONCLUSION This is the first report on the LRS treatment with ultrasound-guided LRB from the contralateral spinous process along the inner side of the articular process by out-plane technique.Further studies are expected to investigate the efficacy and safety of ultrasound-guided LRB for patients with LRS.展开更多
基金supported by Natural Science Foundation of China(62071262)the K.C.Wong Magna Fund at Ningbo University.
文摘In this paper,we reconstruct strongly-decaying block sparse signals by the block generalized orthogonal matching pursuit(BgOMP)algorithm in the l2-bounded noise case.Under some restraints on the minimum magnitude of the nonzero elements of the strongly-decaying block sparse signal,if the sensing matrix satisfies the the block restricted isometry property(block-RIP),then arbitrary strongly-decaying block sparse signals can be accurately and steadily reconstructed by the BgOMP algorithm in iterations.Furthermore,we conjecture that this condition is sharp.
基金supported in part by the National Key R&D Program of China under Grant 2022YFB3104503in part by the China Postdoctoral Science Foundation under Grant 2024M750199+1 种基金in part by the National Natural Science Foundation of China under Grants 62202054,62002022 and 62472251in part by the Fundamental Research Funds for the Central Universities under Grant BLX202360.
文摘In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is also affected by the block length.Therefore,it is crucial to balance the transmission performance and blockchain performance of blockchain communication systems,especially in wireless environments involving UAVs.This paper investigates a secure transmission scheme for blocks in blockchain-based UAV communication systems to prevent the information contained in blocks from being completely eavesdropped during transmission.In our scheme,using a friendly jamming UAV to emit jamming signals diminishes the quality of the eavesdropping channel,thus enhancing the communication security performance of the source UAV.Under the constraints of maneuverability and transmission power of the UAV,the joint design of UAV trajectories,transmission power,and block length are proposed to maximize the average minimum secrecy rate(AMSR).Since the optimization problem is non-convex and difficult to solve directly,we first decompose the optimization problem into subproblems of trajectory optimization,transmission power optimization,and block length optimization.Then,based on firstorder approximation techniques,these subproblems are reformulated as convex optimization problems.Finally,we utilize an alternating iteration algorithm based on the successive convex approximation(SCA)technique to solve these subproblems iteratively.The simulation results demonstrate that our proposed scheme can achieve secure transmission for blocks while maintaining the performance of the blockchain.
文摘A number of publications have claimed that Mobitz type Ⅱ atrioventricular block(AVB)may occur during sleep.None of the reports defined type Ⅱ AVB and representative electrocardiograms were either misinterpreted or missing.Relatively benign Wenckebach type Ⅰ AVB is often misdiagnosed as Mobitz type Ⅱ which is an indication for a pacemaker.Review of the published reports indicates that Mobitz type II AVB does not occur during sleep when it is absent in the awake state.Conclusion:There is no proof that sleep is associated with Mobitz type Ⅱ AVB.
文摘Blockchain technology has witnessed a burgeoning integration into diverse realms of economic and societal development.Nevertheless,scalability challenges,characterized by diminished broadcast efficiency,heightened communication overhead,and escalated storage costs,have significantly constrained the broad-scale application of blockchain.This paper introduces a novel Encode-and CRT-based Scalability Scheme(ECSS),meticulously refined to enhance both block broadcasting and storage.Primarily,ECSS categorizes nodes into distinct domains,thereby reducing the network diameter and augmenting transmission efficiency.Secondly,ECSS streamlines block transmission through a compact block protocol and robust RS coding,which not only reduces the size of broadcasted blocks but also ensures transmission reliability.Finally,ECSS utilizes the Chinese remainder theorem,designating the block body as the compression target and mapping it to multiple modules to achieve efficient storage,thereby alleviating the storage burdens on nodes.To evaluate ECSS’s performance,we established an experimental platformand conducted comprehensive assessments.Empirical results demonstrate that ECSS attains superior network scalability and stability,reducing communication overhead by an impressive 72% and total storage costs by a substantial 63.6%.
文摘BACKGROUND Awake fiberoptic nasotracheal intubation(AFNI)is the preferred airway ma-nagement strategy for patients with difficult airways.However,this procedure can cause significant physical and psychological distress.This case report explores the application of a sphenopalatine ganglion(SPG)block as an alternative anal-gesic modality to mitigate the discomfort associated with AFNI.CASE SUMMARY A 63-year-old female with a history of right maxillary osteosarcoma underwent craniotomy for a suspected malignant brain lesion.The patient’s medical history included prior surgery,chemotherapy,and radiation therapy,resulting in signi-ficant jaw impairment and limited neck mobility.Considering the anticipated air-way challenges,AFNI was planned.A SPG block was performed under real-time ultrasound guidance,providing effective analgesia during nasotracheal intuba-tion.CONCLUSION The SPG block represents a promising analgesic approach in AFNI,offering po-tential benefits in alleviating pain involving the nasal and nasopharyngeal regions as well as improving patient cooperation.
文摘BACKGROUND Anterior cutaneous nerve entrapment syndrome(ACNES)is a condition mani-festing with pain caused by strangulation of the anterior cutaneous branch of the lower intercostal nerves.This case report aims to provide new insight into the selection of peripheral nerve blocks for the ACNES treatment.CASE SUMMARY A 66-year-old woman manifested ACNES after a robot-assisted distal gastrec-tomy.An ultrasound-guided rectal sheath block was effective for pain triggered by the port scar.However,the sudden severe pain,which radiated laterally from the previous site,remained.A transversus abdominis plane block was performed for the remaining pain and effectively relieved it.CONCLUSION In this case,the trocar port was inserted between the rectus and transverse abdominis muscles.The intercostal nerves might have been entrapped on both sides of the rectus and transversus abdominis muscles.Hence,rectus sheath and transverse abdominis plane blocks were required to achieve complete pain relief.To the best of our knowledge,this is the first report on use of a combination of rectus sheath and transverse abdominis plane blocks for pain relief in ACNES.
文摘Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.
文摘Cryogenic block streams consist of a stream of rocks superficially resembling a stream deposit but lacking a matrix, usually occurring on a valley or gully floor or on slopes that are less steep than the maximum angle of repose of coarse sediments. They are usually formed on perennially frozen ground, but can also occur as relict landforms. There are three main active kinds forming today, viz., Siberian and Tibetan dynamic rock streams and lag block streams. During their formation, the blocks in the active Siberian and Tibetan dynamic block streams move downslope at up to 1 rn/a. They are forming today on the Tibetan Plateau and in the more arid parts of south-central Siberia, although the processes involved in the movement are different. In the case of the Tibetan type, individual blocks slide downslope over the substrate in winter on an icy coating in areas of minimal winter precipitation. The Siberian type develops in areas of 15-80 cm of winter snow cover and an MAAT （mean annual air temperature） of-4 ~C to -17 ~C. The movement is due to creep of snow and ice and collapse of the blocks downslope during thawing. Lag block streams are formed by meltwater flowing over the surface of sediment consisting primarily of larger blocks with a limited amount of interstitial sediment. The erosion of the matrix is primarily in the spring in areas of higher winter precipitation on 10^-30~ slopes. The blocks remain stationary, but the interstitial sediment is washed out by strong seasonal flows of meltwater or rain to form an alluvial fan. The boulders undergo weathering and become more rounded in the process. Lag block streams can also develop without the presence of permafrost in areas with cold climates or glaciers. Block streams also occur as relict deposits in older deposits under various climatic regimes that are unsuitable for their formation today. An example of relict lag block streams with subangular to subrounded blocks occurs in gullies on the forested mountainsides at Felsen in Germany, and is the original ＂felsenmeer＂. Similar examples occur near Vitosha Mountain in Bulgaria. The ＂stone runs＂ in the Falkland Islands are examples of the more angular relict lag block streams. In both Tasmania and the Falkland Islands, they mask a more complex history, the underlying soils indicating periods of tropical and temperate soil formation resulting from weathering during and since the Tertiary Period. Block streams have also been reported from beneath cold-based glaciers in Sweden, and below till in Canada, and when ex- humed, can continue to develop.
基金The authors wish to thank National Key R&D Program of China(Grant No.2022YFC308100)the National Nature Science Foundation of China(Grant Nos.42107172 and 42072303)for financial support.
文摘Primary toppling usually occurs in layered rock slopes with large anti-dip angles.In this paper,the block toppling evolution was explored using a large-scale centrifuge system.Each block column in the layered model slope was made of cement mortar.Some artificial cracks perpendicular to the block column were prefabricated.Strain gages,displacement gages,and high-speed camera measurements were employed to monitor the deformation and failure processes of the model slope.The centrifuge test results show that the block toppling evolution can be divided into seven stages,i.e.layer compression,formation of major tensile crack,reverse bending of the block column,closure of major tensile crack,strong bending of the block column,formation of failure zone,and complete failure.Block toppling is characterized by sudden large deformation and occurs in stages.The wedge-shaped cracks in the model incline towards the slope.Experimental observations show that block toppling is mainly caused by bending failure rather than by shear failure.The tensile strength also plays a key factor in the evolution of block toppling.The simulation results from discrete element method(DEM)is in line with the testing results.Tensile stress exists at the backside of rock column during toppling deformation.Stress concentration results in the fragmented rock column and its degree is the most significant at the slope toe.
基金the National Natural Science Foundation of China(Grant number 51771178)Shaanxi Outstanding Youth Fund project(Grant number 2021JC-45)+2 种基金Key international cooperation projects in Shaanxi Province(Grant number 2020KWZ-007)the Major Program of Science and Technology in Shaanxi Province(Grant number20191102006)Open Fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body(Grant number 32115019)。
文摘The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various industries.The conventional epoxy coating easily forms many intrinsic defects during the solidification process,which cannot provide sufficient protection.In the current study,we design a double-layer epoxy composite coating on Mg alloy with enhanced anti-corrosion/wear properties,via the spin-assisted assembly technique.The outer layer is functionalized graphene(FG)in waterborne epoxy resin(WEP)and the inner layer is Ce-based conversion(Ce)film.The FG sheets can be homogeneously dispersed within the epoxy matrix to fill the intrinsic defects and improve the barrier capability.The Ce film connects the outer layer with the substrate,showing the transition effect.The corrosion rate of Ce/WEP/FG composite coating is 2131 times lower than that of bare Mg alloy,and the wear rate is decreased by~90%.The improved corrosion resistance is attributed to the labyrinth effect(hindering the penetration of corrosive medium)and the obstruction of galvanic coupling behavior.The synergistic effect derived from the FG sheet and blocking layer exhibits great potential in realizing the improvement of multi-functional integration,which will open up a new avenue for the development of novel composite protection coatings of Mg alloys.
基金Supported by the National Natural Science Foundation of China,No.82305380The Postdoctoral Research Program,West China Hospital,Sichuan University,No.2020HXBH018.
文摘BACKGROUND Ultrasound guide technology,which can provide real-time visualization of the needle tip and tissues and avoid many adverse events,is widely used in mini-mally invasive therapy.However,the studies on ultrasound-guided Lateral recess block(LRB)are limited,this is probably because there is no recognized standard method for ultrasound scanning.This study aimed to evaluate the effect of ultrasound-guided LRB in patients with lateral recess stenosis(LRS).CASE SUMMARY A 65-year-old patient complained of low back pain accompanied occasionally by pain and numbness in the left lower limb.Physical examination showed ten-derness on the spinous process and paraspinal muscles from L1 to S1,extensor hallucis longus and tibialis anterior weakness(muscle strength:4-),and a positive straight leg raising test in the left lower limb(60°).Magnetic resonance imaging showed L4–L5 disc degeneration with left LRS and nerve root entrapment.Subsequently,the patient was diagnosed with LRS.This patient was treated with a novel ultrasound-guided LRB approach.The patient’s symptoms significantly improved without any complications at 1 wk postoperatively and at the 3-month follow-up.CONCLUSION This is the first report on the LRS treatment with ultrasound-guided LRB from the contralateral spinous process along the inner side of the articular process by out-plane technique.Further studies are expected to investigate the efficacy and safety of ultrasound-guided LRB for patients with LRS.
