A combination of experimental measurements and numerical analysis was utilized to study the low-velocity impact damage of domestic carbon fiber-reinforced composites(CFRCs).The results indicated that the low-velocity ...A combination of experimental measurements and numerical analysis was utilized to study the low-velocity impact damage of domestic carbon fiber-reinforced composites(CFRCs).The results indicated that the low-velocity impact damage induced pits and longitudinal cracks on the front side,oblique cracks and delaminationin on the back side.The pit depth increased with the increasing impact energy.It was demonstrated that the numerical analysis strain history curve was similar to the experimentally measured strain history curve,which verified the accuracy of numerical analysis in which the Hashin failure criterion was used.The work provides basic data and theoretical basis for the promotion and application of the domestic carbon fiber,and demonstrates the feasibility of replacing imported carbon fibers with domestic carbon fibers.展开更多
BACKGROUND Delayed post hypoxic leukoencephalopathy syndrome(DPHLS),also known as Grinker’s myelinopathy,is a rare but significant neurological condition that manifests days to weeks after a hypoxic event.Characteriz...BACKGROUND Delayed post hypoxic leukoencephalopathy syndrome(DPHLS),also known as Grinker’s myelinopathy,is a rare but significant neurological condition that manifests days to weeks after a hypoxic event.Characterized by delayed onset of neurological and cognitive deficits,DPHLS presents substantial diagnostic and therapeutic challenges.AIM To consolidate current knowledge on pathophysiology,clinical features,diagnostic approaches,and management strategies for DPHLS,providing a comprehensive overview and highlighting gaps for future research.METHODS Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes guidelines,we systematically searched PubMed,ScienceDirect and Hinari databases using terms related to delayed post-hypoxic leukoencephalopathy.Inclusion criteria were original research articles,case reports,and case series involving human subjects with detailed clinical,neuroimaging,or pathological data on DPHLS.Data were extracted on study characteristics,participant demographics,clinical features,neuroimaging findings,pathological findings,treatment,and outcomes.The quality assessment was performed using the Joanna Briggs Institute critical appraisal checklist.RESULTS A total of 73 cases were reviewed.Common comorbidities included schizoaffective disorder,bipolar disorder,hypertension,and substance use disorder.The primary causes of hypoxia were benzodiazepine overdose,opioid overdose,polysubstance overdose,and carbon monoxide(CO)poisoning.Symptoms frequently include decreased level of consciousness,psychomotor agitation,cognitive decline,parkinsonism,and encephalopathy.Neuroimaging commonly revealed diffuse T2 hyperintensities in cerebral white matter,sometimes involving the basal ganglia and the globus pallidus.Magnetic resonance spectroscopy often showed decreased N-acetylaspartate,elevated choline,choline-to-creatinine ratio,and normal or elevated lactate.Treatment is often supportive,including amantadine,an antioxidant cocktail,and steroids.Hyperbaric oxygen therapy may be beneficial in those with CO poisoning.Parkinsonism was often treated with levodopa.Most of the patients had substantial recovery over the course of months and many cases had some residual neurocognitive deficits.CONCLUSION DPHLS remains a complex and multifaceted condition with various etiologies and clinical manifestations.Early recognition and appropriate management are crucial to improving patient outcomes.Future research should focus on standardizing diagnostic criteria,using advanced imaging techniques,and exploring therapeutic interventions to improve understanding and treatment of DPHLS.Conducting prospective cohort studies and developing biomarkers for early diagnosis and monitoring will be essential to advance patient care.展开更多
Fiber-reinforced polymer(FRP)wrapping is a potential technique for coal pillar reinforcement.In this study,an acoustic emission(AE)technique was employed to monitor coal specimens with carbon FRP(CFRP)jackets during u...Fiber-reinforced polymer(FRP)wrapping is a potential technique for coal pillar reinforcement.In this study,an acoustic emission(AE)technique was employed to monitor coal specimens with carbon FRP(CFRP)jackets during uniaxial compression,which addressed the inability to observe the cracks inside the FRP-reinforced coal pillars by conventional field inspection techniques.The spatiotemporal fractal evolution of the cumulated AE events during loading was investigated based on fractal theory.The results indicated that the AE response and fractal features of the coal specimens were closely related to their damage evolution,with CFRP exerting a significant influence.In particular,during the unstable crack development stage,the evolutionary patterns of the AE count and energy curves of the CFRPconfined specimens underwent a transformation from the slight shockemajor shock type to the slight shockesub-major shockeslight shockemajor shock type,in contrast to the unconfined coal specimens.The AE b-values decreased to a minimum and then increased marginally.The AE spatial fractal dimension increased rapidly,whereas the AE temporal fractal dimension fluctuated significantly during the accumulation and release of strain energy.Ultimately,based on the AE count and AE energy evolution,a damage factor was proposed for the coal samples with CFRP jackets.Furthermore,a damage constitutive model was established,considering the CFRP jacket and the compaction characteristics of the coal.This model provides an effective description of the stressestrain relationship of coal specimens with CFRP jackets.展开更多
Solid-phase-sintered Si C-based composites with short carbon fibers（Csf/SSi C） in concentrations ranging from 0 to 10wt% were prepared by pressureless sintering at 2100°C. The phase composition, microstructure,...Solid-phase-sintered Si C-based composites with short carbon fibers（Csf/SSi C） in concentrations ranging from 0 to 10wt% were prepared by pressureless sintering at 2100°C. The phase composition, microstructure, density, and flexural strength of the composites with different Csf contents were investigated. SEM micrographs showed that the Csf distributed in the SSi C matrix homogeneously with some gaps at the fiber/matrix interfaces. The densities of the composites decreased with increasing Csf content. However, the bending strength first increased and then decreased with increasing Csf content, reaching a maximum value of 390 MPa at a Csf content of 5wt%, which was 60 MPa higher than that of SSi C because of the pull-out strengthening mechanism. Notably, Csf was graphitized and damaged during the sintering process because of the high temperature and reaction with boron derived from the sintering additive B4C; this graphitization degraded the fiber strengthening effect.展开更多
Reclaimed mine soils (RMS) which develop on post-mining sites play significant role in Carbon sequestration in new ecosystems, especially in local range on areas disturbed by human activity. This study presents the po...Reclaimed mine soils (RMS) which develop on post-mining sites play significant role in Carbon sequestration in new ecosystems, especially in local range on areas disturbed by human activity. This study presents the potential for Carbon sequestration in RMS developing on 3 post sur- face mining areas in Poland (Central Europe) reforested with Scots pine (Pinus sylvestris L). Research was conducted on waste heaps and quarry which accompany open cast lignite, sul- fur, and sand mining. Control plots were arrang- ed in managed pine forests on natural sites in the surrounding area. The results shows high Carbon accumulation in RMS, estimated on 16.77 Mg?ha-1 in poor (oligotrofic) soils on Quaternary sands on sand quarry and up to 65.03 Mg?ha-1 on external waste heap after Sulfur sur- face mining exploitation on Quaternary sands mixed with Tertiary clays. These results were very similar to natural forest soils on control plots. Potential rate of Carbon sequestration in RMS was estimated on 0.73 (on the poorest sa- ndy soils on quarry) to 2.17 Mg?ha-1?yr-1 (on potentially abundant sandy-clayish soils on Sulfur waste heap), and 5.26 Mg?ha-1?yr-1 (on Tertiary sands substrate soils on lignite mining waste heap). In conslusion the average Carbon accu- mulation in RMS was estimated on 41 Mg?ha-1 and Carbon sequestration rate was 1.45 Mg? ha-1?yr-1. According to the result of this study and range of post-mining areas reclaimed to forestry in Poland (ca 15000 ha) total Carbon accumulation in RMS was estimated on 615 × 103 Mg and potential Carbon sequestration rate in new ecosystems on 21.75 × 103 Mg?ha-1?yr-1. However, the main factors affecting Carbon sequestration and protection in RMS under tree stand were substrate, percentage of clay and silt sized fraction, in order to formulate guidelines for sustainable management of post-mining ec- osystem, further study must be continue for be- tter understanding.展开更多
The discovery of silicate carbon star poses a challenge to the theory of stellar evolution in the late stage, hence it is important to look for more silicate carbon stars. To this end we have carried out cross-identif...The discovery of silicate carbon star poses a challenge to the theory of stellar evolution in the late stage, hence it is important to look for more silicate carbon stars. To this end we have carried out cross-identifications between the new IRAS Low-Resolution Spectrum （LRS） database and the new carbon star catalog, CGCS3. We have found nine new silicate carbon stars with silicate features around 10μm and/or 18 μm. These newly identified stars are located in the Regions Ilia and VII in the IRAS two-color diagram, which means they indeed have typical far infrared colors of silicate carbon stars. The infrared properties of each of these sources are discussed.展开更多
The properties and classification of IRAS 19111+2555 have so far not been well determined. We collect all the available information and data of this star, and take the data obtained by IRAS LRS and ISO SWS to discuss ...The properties and classification of IRAS 19111+2555 have so far not been well determined. We collect all the available information and data of this star, and take the data obtained by IRAS LRS and ISO SWS to discuss its properties and classification. The star is found to have a 3.1μm feature in absorption and a 10μm feature in emission, so it is possibly a new silicate carbon star.展开更多
As an important component,the bond behavior of carbon fiber-reinforced polymer(CFRP)-concrete interface for a reinforced concrete(RC)beam is very significant.In this study,a theoretical model was established to analyz...As an important component,the bond behavior of carbon fiber-reinforced polymer(CFRP)-concrete interface for a reinforced concrete(RC)beam is very significant.In this study,a theoretical model was established to analyze the flexural behavior of CFRP-strengthened RC beams,and the CFRP-concrete interfacial bond-slip relationship under hygrothermal environment was unified into one model.Two failure criteria corresponding to two types of failure modes,i.e.,concrete crushing and intermediate crack(IC)-induced debonding,were developed.Through the theoretical model,the flexural behavior of deflection,interfacial shear stress distribution and ultimate load of a CFRP-strengthened RC beam under hygrothermal environment were obtained and predicted.Moreover,the theoretical model was verified by test results.The results showed that the hygrothermal environment had a significant impact on the CFRP-concrete interface behavior.Compared with the control beam without hygrothermal environment pretreatment,the deflection and ultimate load of the strengthened RC beam decreased by 51.9%and 20%,respectively.展开更多
基金Funded by the Fundamental Research Funds for the Central Universities(No.2018IB001)and the National High-tech Research and Development Program of China(863 Program)(No.2013AA031306)。
文摘A combination of experimental measurements and numerical analysis was utilized to study the low-velocity impact damage of domestic carbon fiber-reinforced composites(CFRCs).The results indicated that the low-velocity impact damage induced pits and longitudinal cracks on the front side,oblique cracks and delaminationin on the back side.The pit depth increased with the increasing impact energy.It was demonstrated that the numerical analysis strain history curve was similar to the experimentally measured strain history curve,which verified the accuracy of numerical analysis in which the Hashin failure criterion was used.The work provides basic data and theoretical basis for the promotion and application of the domestic carbon fiber,and demonstrates the feasibility of replacing imported carbon fibers with domestic carbon fibers.
文摘BACKGROUND Delayed post hypoxic leukoencephalopathy syndrome(DPHLS),also known as Grinker’s myelinopathy,is a rare but significant neurological condition that manifests days to weeks after a hypoxic event.Characterized by delayed onset of neurological and cognitive deficits,DPHLS presents substantial diagnostic and therapeutic challenges.AIM To consolidate current knowledge on pathophysiology,clinical features,diagnostic approaches,and management strategies for DPHLS,providing a comprehensive overview and highlighting gaps for future research.METHODS Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes guidelines,we systematically searched PubMed,ScienceDirect and Hinari databases using terms related to delayed post-hypoxic leukoencephalopathy.Inclusion criteria were original research articles,case reports,and case series involving human subjects with detailed clinical,neuroimaging,or pathological data on DPHLS.Data were extracted on study characteristics,participant demographics,clinical features,neuroimaging findings,pathological findings,treatment,and outcomes.The quality assessment was performed using the Joanna Briggs Institute critical appraisal checklist.RESULTS A total of 73 cases were reviewed.Common comorbidities included schizoaffective disorder,bipolar disorder,hypertension,and substance use disorder.The primary causes of hypoxia were benzodiazepine overdose,opioid overdose,polysubstance overdose,and carbon monoxide(CO)poisoning.Symptoms frequently include decreased level of consciousness,psychomotor agitation,cognitive decline,parkinsonism,and encephalopathy.Neuroimaging commonly revealed diffuse T2 hyperintensities in cerebral white matter,sometimes involving the basal ganglia and the globus pallidus.Magnetic resonance spectroscopy often showed decreased N-acetylaspartate,elevated choline,choline-to-creatinine ratio,and normal or elevated lactate.Treatment is often supportive,including amantadine,an antioxidant cocktail,and steroids.Hyperbaric oxygen therapy may be beneficial in those with CO poisoning.Parkinsonism was often treated with levodopa.Most of the patients had substantial recovery over the course of months and many cases had some residual neurocognitive deficits.CONCLUSION DPHLS remains a complex and multifaceted condition with various etiologies and clinical manifestations.Early recognition and appropriate management are crucial to improving patient outcomes.Future research should focus on standardizing diagnostic criteria,using advanced imaging techniques,and exploring therapeutic interventions to improve understanding and treatment of DPHLS.Conducting prospective cohort studies and developing biomarkers for early diagnosis and monitoring will be essential to advance patient care.
基金supported by Yunlong Lake Laboratory of Deep Underground Science and Engineering Project(Grant No.104024003)the Natural Science Foundation of the Jiangsu Provincial Basic Research Program(Grant No.BK20220024)the Open Sharing Fund for the large-scale instruments and equipment of the China University of Mining and Technology(Grant No.DYGX-2023-044).
文摘Fiber-reinforced polymer(FRP)wrapping is a potential technique for coal pillar reinforcement.In this study,an acoustic emission(AE)technique was employed to monitor coal specimens with carbon FRP(CFRP)jackets during uniaxial compression,which addressed the inability to observe the cracks inside the FRP-reinforced coal pillars by conventional field inspection techniques.The spatiotemporal fractal evolution of the cumulated AE events during loading was investigated based on fractal theory.The results indicated that the AE response and fractal features of the coal specimens were closely related to their damage evolution,with CFRP exerting a significant influence.In particular,during the unstable crack development stage,the evolutionary patterns of the AE count and energy curves of the CFRPconfined specimens underwent a transformation from the slight shockemajor shock type to the slight shockesub-major shockeslight shockemajor shock type,in contrast to the unconfined coal specimens.The AE b-values decreased to a minimum and then increased marginally.The AE spatial fractal dimension increased rapidly,whereas the AE temporal fractal dimension fluctuated significantly during the accumulation and release of strain energy.Ultimately,based on the AE count and AE energy evolution,a damage factor was proposed for the coal samples with CFRP jackets.Furthermore,a damage constitutive model was established,considering the CFRP jacket and the compaction characteristics of the coal.This model provides an effective description of the stressestrain relationship of coal specimens with CFRP jackets.
基金financially supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20110006110025)the National Natural Science Foundation of China(No.U1134102)
文摘Solid-phase-sintered Si C-based composites with short carbon fibers（Csf/SSi C） in concentrations ranging from 0 to 10wt% were prepared by pressureless sintering at 2100°C. The phase composition, microstructure, density, and flexural strength of the composites with different Csf contents were investigated. SEM micrographs showed that the Csf distributed in the SSi C matrix homogeneously with some gaps at the fiber/matrix interfaces. The densities of the composites decreased with increasing Csf content. However, the bending strength first increased and then decreased with increasing Csf content, reaching a maximum value of 390 MPa at a Csf content of 5wt%, which was 60 MPa higher than that of SSi C because of the pull-out strengthening mechanism. Notably, Csf was graphitized and damaged during the sintering process because of the high temperature and reaction with boron derived from the sintering additive B4C; this graphitization degraded the fiber strengthening effect.
文摘Reclaimed mine soils (RMS) which develop on post-mining sites play significant role in Carbon sequestration in new ecosystems, especially in local range on areas disturbed by human activity. This study presents the potential for Carbon sequestration in RMS developing on 3 post sur- face mining areas in Poland (Central Europe) reforested with Scots pine (Pinus sylvestris L). Research was conducted on waste heaps and quarry which accompany open cast lignite, sul- fur, and sand mining. Control plots were arrang- ed in managed pine forests on natural sites in the surrounding area. The results shows high Carbon accumulation in RMS, estimated on 16.77 Mg?ha-1 in poor (oligotrofic) soils on Quaternary sands on sand quarry and up to 65.03 Mg?ha-1 on external waste heap after Sulfur sur- face mining exploitation on Quaternary sands mixed with Tertiary clays. These results were very similar to natural forest soils on control plots. Potential rate of Carbon sequestration in RMS was estimated on 0.73 (on the poorest sa- ndy soils on quarry) to 2.17 Mg?ha-1?yr-1 (on potentially abundant sandy-clayish soils on Sulfur waste heap), and 5.26 Mg?ha-1?yr-1 (on Tertiary sands substrate soils on lignite mining waste heap). In conslusion the average Carbon accu- mulation in RMS was estimated on 41 Mg?ha-1 and Carbon sequestration rate was 1.45 Mg? ha-1?yr-1. According to the result of this study and range of post-mining areas reclaimed to forestry in Poland (ca 15000 ha) total Carbon accumulation in RMS was estimated on 615 × 103 Mg and potential Carbon sequestration rate in new ecosystems on 21.75 × 103 Mg?ha-1?yr-1. However, the main factors affecting Carbon sequestration and protection in RMS under tree stand were substrate, percentage of clay and silt sized fraction, in order to formulate guidelines for sustainable management of post-mining ec- osystem, further study must be continue for be- tter understanding.
基金Supported by the National Natural Science Foundation of China.
文摘The discovery of silicate carbon star poses a challenge to the theory of stellar evolution in the late stage, hence it is important to look for more silicate carbon stars. To this end we have carried out cross-identifications between the new IRAS Low-Resolution Spectrum （LRS） database and the new carbon star catalog, CGCS3. We have found nine new silicate carbon stars with silicate features around 10μm and/or 18 μm. These newly identified stars are located in the Regions Ilia and VII in the IRAS two-color diagram, which means they indeed have typical far infrared colors of silicate carbon stars. The infrared properties of each of these sources are discussed.
文摘The properties and classification of IRAS 19111+2555 have so far not been well determined. We collect all the available information and data of this star, and take the data obtained by IRAS LRS and ISO SWS to discuss its properties and classification. The star is found to have a 3.1μm feature in absorption and a 10μm feature in emission, so it is possibly a new silicate carbon star.
基金The authors would like to acknowledge the financial support from the National Natural Science Foundation of China(Nos.11872185,11627802,51678249,11132004)the Natural Science Foundation of Guangdong Province(No.2019A1515012222).
文摘As an important component,the bond behavior of carbon fiber-reinforced polymer(CFRP)-concrete interface for a reinforced concrete(RC)beam is very significant.In this study,a theoretical model was established to analyze the flexural behavior of CFRP-strengthened RC beams,and the CFRP-concrete interfacial bond-slip relationship under hygrothermal environment was unified into one model.Two failure criteria corresponding to two types of failure modes,i.e.,concrete crushing and intermediate crack(IC)-induced debonding,were developed.Through the theoretical model,the flexural behavior of deflection,interfacial shear stress distribution and ultimate load of a CFRP-strengthened RC beam under hygrothermal environment were obtained and predicted.Moreover,the theoretical model was verified by test results.The results showed that the hygrothermal environment had a significant impact on the CFRP-concrete interface behavior.Compared with the control beam without hygrothermal environment pretreatment,the deflection and ultimate load of the strengthened RC beam decreased by 51.9%and 20%,respectively.
