When subjected to sustained high temperatures,the structure of the continuous China railway track system(CRTS)II railway track is susceptible to internal axial pressure,leading to joint damage and the potential for up...When subjected to sustained high temperatures,the structure of the continuous China railway track system(CRTS)II railway track is susceptible to internal axial pressure,leading to joint damage and the potential for upwarp buckling of the track slab.This study employs model testing to derive the upwarp buckling deformation curve of the track slab under conditions of joint damage.An analytical expression for the upwarp buckling equilibrium path of the track slab is derived through the application of the energy principle.Validation of the outcomes is performed by the comparison with experimental data.The effects of initial upwarp amplitude,initial upwarp curve type,elastic modulus,thickness,and gravity load on the upwarp buckling response of the track slab were investigated.The results show that:1)The upwarp deformation of the track slab in the narrow joint damage state is concentrated in a minor range on both sides of the joint,forming an inverted‘V’shape with concave ends.2)The joint damage can significantly reduce the upwarp buckling critical temperature rise of the track slab.3)The magnitude of the initial upwarp amplitude dictates the buckling mode of the track slab,while the initial upwarp curve predominantly influences the upwarp buckling critical temperature rise.Notably,an initial upwarp amplitude below 6.5 mm ensures the buckling resistance for up to a 60℃temperature rise.4)The increases in elastic modulus,gravity load,and track slab thickness can increase the upwarp buckling critical temperature rise.As the initial upwarp amplitude increases,the influence of these factors on the upwarp buckling critical temperature rise of the track slab gradually diminishes.展开更多
The ultimately exposed roof area(UERA)of goaf is crucial to the safety and economics of underground mining.The prediction models do not consider the mechanical weakness of rock mass and ignore the influence of the joi...The ultimately exposed roof area(UERA)of goaf is crucial to the safety and economics of underground mining.The prediction models do not consider the mechanical weakness of rock mass and ignore the influence of the joint damage factor,causing a large predicted exposure area with a high roof falling risk.This work adopted joint damage factor to derive a new UERA prediction model.The relationships between the UERA(S)and the span ratio(m),the density(k)and the diameter of fracture(d)were analysed by the new prediction model.The results showed that the exposed area S and the span ratio m have a U-shaped curve relationship.The S decreases with the increase of m and then increases when m is beyond 2.The exposed roof area S is in an inversely proportional power-law relationship with the fracture surface density k,and the curvature of the S-k relationship curve decreases when d=0.5 and k>7,and S is close to 0.There is a negative correlation between S and the fracture surface diameter d,the curvature of the S-d curve decreases with the increase of d and k,and the variation rate increases first and then decreases with the increase of d;when k=0.5 and d>9,S is close to 0.The predicted values of the UERA prediction model are 119.3,112.8,and 114.6 m2 with different joint damage parameters,which are slightly smaller than the actual critical exposure area of a roof(S=120 m2).The case study shows that the alternative prediction model is reasonable and acceptable and provides new theoretical support for the underground mining safety of sedimentary bauxite ore.展开更多
BACKGROUND A disease caused by a novel coronavirus virus,named coronavirus disease 2019(COVID-19),broke out in Wuhan,China in December 2019,and spread around the word.As of March 4,2020,93090 confirmed cases and 2984 ...BACKGROUND A disease caused by a novel coronavirus virus,named coronavirus disease 2019(COVID-19),broke out in Wuhan,China in December 2019,and spread around the word.As of March 4,2020,93090 confirmed cases and 2984 deaths have been reported in more than 80 countries and territories.It has triggered global public health security.However,the features and prognosis of COVID-19 are incompletely understood.CASE SUMMARY We here report that the erythrocyte sedimentation rate(ESR)increased in a confirmed COVID patient.The high level of ESR sustained for a long time even after the patient recovered from COVID-19,while all results related to tumor,tuberculosis,rheumatic diseases,anemia,etc.cannot explain the abnormal elevation of ESR presented in this case.CONCLUSION Although the increased ESR cannot be explained by all existing evidence,it possibly links the abnormal pathologic change in some COVID-19 patients and negative prognosis,and provides the clue to dissect the mechanism of illness progressing in COVID-19 and its prognosis.展开更多
Rheumatoid arthritis(RA)is an autoimmune disorder char-acterized by synovial joint damage and progressive loss of mobility.The human leukocyte antigen(HLA)classⅡalleles HLA-DRB1^(*)01:01 and HLA-DRB1^(*)04:01 are str...Rheumatoid arthritis(RA)is an autoimmune disorder char-acterized by synovial joint damage and progressive loss of mobility.The human leukocyte antigen(HLA)classⅡalleles HLA-DRB1^(*)01:01 and HLA-DRB1^(*)04:01 are strongly linked to RA susceptibility.展开更多
基金supported by the National Natural Science Foundation of China(No.52278459).
文摘When subjected to sustained high temperatures,the structure of the continuous China railway track system(CRTS)II railway track is susceptible to internal axial pressure,leading to joint damage and the potential for upwarp buckling of the track slab.This study employs model testing to derive the upwarp buckling deformation curve of the track slab under conditions of joint damage.An analytical expression for the upwarp buckling equilibrium path of the track slab is derived through the application of the energy principle.Validation of the outcomes is performed by the comparison with experimental data.The effects of initial upwarp amplitude,initial upwarp curve type,elastic modulus,thickness,and gravity load on the upwarp buckling response of the track slab were investigated.The results show that:1)The upwarp deformation of the track slab in the narrow joint damage state is concentrated in a minor range on both sides of the joint,forming an inverted‘V’shape with concave ends.2)The joint damage can significantly reduce the upwarp buckling critical temperature rise of the track slab.3)The magnitude of the initial upwarp amplitude dictates the buckling mode of the track slab,while the initial upwarp curve predominantly influences the upwarp buckling critical temperature rise.Notably,an initial upwarp amplitude below 6.5 mm ensures the buckling resistance for up to a 60℃temperature rise.4)The increases in elastic modulus,gravity load,and track slab thickness can increase the upwarp buckling critical temperature rise.As the initial upwarp amplitude increases,the influence of these factors on the upwarp buckling critical temperature rise of the track slab gradually diminishes.
基金This work is supported by the National Natural Science Foundation of China(51974135,51704094)the National Key Research and Development Program of China(2016YFC0600802).
文摘The ultimately exposed roof area(UERA)of goaf is crucial to the safety and economics of underground mining.The prediction models do not consider the mechanical weakness of rock mass and ignore the influence of the joint damage factor,causing a large predicted exposure area with a high roof falling risk.This work adopted joint damage factor to derive a new UERA prediction model.The relationships between the UERA(S)and the span ratio(m),the density(k)and the diameter of fracture(d)were analysed by the new prediction model.The results showed that the exposed area S and the span ratio m have a U-shaped curve relationship.The S decreases with the increase of m and then increases when m is beyond 2.The exposed roof area S is in an inversely proportional power-law relationship with the fracture surface density k,and the curvature of the S-k relationship curve decreases when d=0.5 and k>7,and S is close to 0.There is a negative correlation between S and the fracture surface diameter d,the curvature of the S-d curve decreases with the increase of d and k,and the variation rate increases first and then decreases with the increase of d;when k=0.5 and d>9,S is close to 0.The predicted values of the UERA prediction model are 119.3,112.8,and 114.6 m2 with different joint damage parameters,which are slightly smaller than the actual critical exposure area of a roof(S=120 m2).The case study shows that the alternative prediction model is reasonable and acceptable and provides new theoretical support for the underground mining safety of sedimentary bauxite ore.
基金Supported by the Central Publicinterest Scientific Institution Basal Research Fund,Chinese Academy of Medical Sciences,No.2019PT320003Science and Technology Support Plan Fund of Zunyi City,No.NS(2020)1and Science Plan Fund of Zunyi City,No.HZ(2020)4.
文摘BACKGROUND A disease caused by a novel coronavirus virus,named coronavirus disease 2019(COVID-19),broke out in Wuhan,China in December 2019,and spread around the word.As of March 4,2020,93090 confirmed cases and 2984 deaths have been reported in more than 80 countries and territories.It has triggered global public health security.However,the features and prognosis of COVID-19 are incompletely understood.CASE SUMMARY We here report that the erythrocyte sedimentation rate(ESR)increased in a confirmed COVID patient.The high level of ESR sustained for a long time even after the patient recovered from COVID-19,while all results related to tumor,tuberculosis,rheumatic diseases,anemia,etc.cannot explain the abnormal elevation of ESR presented in this case.CONCLUSION Although the increased ESR cannot be explained by all existing evidence,it possibly links the abnormal pathologic change in some COVID-19 patients and negative prognosis,and provides the clue to dissect the mechanism of illness progressing in COVID-19 and its prognosis.
基金supported by the Russian Science Foundation(No.22-14-00219).
文摘Rheumatoid arthritis(RA)is an autoimmune disorder char-acterized by synovial joint damage and progressive loss of mobility.The human leukocyte antigen(HLA)classⅡalleles HLA-DRB1^(*)01:01 and HLA-DRB1^(*)04:01 are strongly linked to RA susceptibility.
