Purpose-Temperature is an important load for a ballastless track.However,little research has been conducted on the dynamic responses when a train travels on a ballastless track under the temperature gradient.The dynam...Purpose-Temperature is an important load for a ballastless track.However,little research has been conducted on the dynamic responses when a train travels on a ballastless track under the temperature gradient.The dynamic responses under different temperature gradients of the slab are theoretically investigated in this work.Design/methodology/approach-Considering the moving train,the temperature gradient of the slab,and the gravity of the slab track,a dynamic model for a high-speed train that runs along the CRTS Ⅲ slab track on subgrade is developed by a nonlinear coupled way in Abaqus.Findings-The results are as follows:(1)The upward transmission of the periodic deformation of the slab causes periodic track irregularity.(2)Because of the geometric constraint of limiting structures,the maximum bending stresses of the slab occur near the end of the slab under positive temperature gradients,but in the middle of the slab under negative temperature gradients.(3)The periodic deformation of the slab can induce periodic changes in the interlayer stiffness and contact status,leading to a large vibration of the slab.Because of the vibration-reduction capacity of the fastener and the larger mass of the concrete base,the accelerations of both the slab and concrete base are far less than the acceleration of the rail.Originality/value-This study reveals the influence mechanism of temperature gradient-induced periodic deformation in the dynamic responses of the train-track system,and it also provides a guide for the safe service of CRTS Ⅲ slab track.展开更多
BACKGROUND： Glutathione, as an in vivo free radical scavenger, plays an important role in the anti-oxidation defense mechanism in patients with acute cerebral infarction. OBJECTIVE： To observe the relationship betwe...BACKGROUND： Glutathione, as an in vivo free radical scavenger, plays an important role in the anti-oxidation defense mechanism in patients with acute cerebral infarction. OBJECTIVE： To observe the relationship between the levels of glutathione （GSH） and malonaldehyde （MDA）, the metabolite of lipid peroxidation, in erythrocyte and deformation index of erythrocyte in patients at various periods following acute cerebral infarction. DESIGN： Controlled observation.SETTING： Qilu Hospital of Shandong University and Institute of Cerebrovascular Disease of Qingdao Medical College. PARTICIPANTS： We chose 98 inpatients with acute cerebral infarction from Department of Neurology, Qilu Hospital of Shandong University from January to December 2000 , serving as cerebral infarction group, including 50 male and 48 female, with mean age of （62±7）years. There were 23 cases found on the 1^st day after onset; 25 cases on the 3^rd day after onset; 25 cases on the 7^th day after onset; 25 cases on the 14th days after onset, and they were all confirmed by craniocerebral CT or MRI. Another 30 homeochronous inpatients with neurosis, cervical syndrome, lumbar intervertebral disc herniation and motor neuron disease were chosen as control group, including 20 male and 10 female, with mean age of （52±8）years . There was no significant difference in age and gender distribution between two groups （P 〉 0.05）. Patients in the two groups were informed of detected index.METHODS：①Ulnar venous blood was chosen from the patients who were fasted on the 1^st, 3^rd,7^th and 14^th days after onset. Deformation index of erythrocyte was measured with BL88-CKX laser diffraction erythrocyte deformeter and photographing was performed. GSH level in erythrocyte was measured with DTNB assay introduced by Beu-tler. MDA level in erythrocyte was measured with modified thiobarbituric acid colorimetric method.②At each sample collecting , according to the criteria accepted by the Fourth National Conference of Cerebrovascular Disease, intergrant of neurologic impairment 〈 15 points was regarded as mild （n=46）, 15 to 30 points as moderate （n=40）and, 〉 30 points as severe （n=12）. ③ t test was used to compare data between two groups , and linear correlation analysis was used in relationship analysis among indexes. MAIN OUTCOME MEASURES ：① Comparison of erythrocyte GSH and MDA levels and deformation index of erythrocyte at various periods between patients with acute cerebral infarction and controls. ②Correlation of erythrocyte GSH level with erythrocyte MDA level and with deformation index of erythrocyte in patients with cerebral infarction . ③ Relationship between erythrocyte GSH level and severity of disease in patients with acute cerebral infarction. RESULTS： Totally 98 patients with acute cerebral infarction and 30 controls all entered the stage of result analysis. ① Erythrocyte GSH level and deformation index of erythrocyte were lower on the 1^st, 3^rd, 7^th and 14^th days after onset in cerebral infarction group than in control group （P 〈 0.05-0.01）, and erythrocyte MDA level was significantly higher in cerebral infarction group than in control group （P 〈 0.05-0.01）. The three indexes changed most significantly on day 3 after onset in patients, and began to recover or decrease on day 7 after onset and inclined to be normal on day 14 after onset. ② Erythrocyte GSH level was significantly negatively correlated with erythrocyte MDA level in patients with acute cerebral infarction on the 1^st, 3^rd, 7^th and 14^th days after onset （r=-0.534, -0.713, -0.645, -0.656, respectively, P 〈 0.05-0.01 ） ,and significantly positively correlated with erythrocyte deformation index （t-=0.502, 0.560, 0.455, 0.504, respectively, P 〈 0.05）. ③Erythrocyte GSH level was significantly lower in moderate or severe patients with acute cerebral infarction than in mild patients[（0.215±0.088）,（0.192±0.102）, （0.281±0.090） g/L, P〈 0.05]. CONCLUSION：①Erythrocyte GSH and MDA levels and deformation index of erythrocyte change significantly on the 3^rd day following acute cerebral infarction. Index detection results gradually tended to be normal on from the 7^th day to 14^th days day after onset. ② Change of erythrocyte GSH level can reflect the severity of disease of patients with acute cerebral infarction.③Decrease of erythrocyte GSH level in patients with acute cerebral infarction is one of reasons that result in the decrease of deformation ability of erythrocyte.展开更多
基金supported by National Key R&D Program of China[Grant No.2022YFB2603400]R&D Project of China State Railway Group Corporation Limited[Grant No.P2021G053]R&D Project of China Academy of Railway Science Corporation Limited[Grant No.2023YJ200].
文摘Purpose-Temperature is an important load for a ballastless track.However,little research has been conducted on the dynamic responses when a train travels on a ballastless track under the temperature gradient.The dynamic responses under different temperature gradients of the slab are theoretically investigated in this work.Design/methodology/approach-Considering the moving train,the temperature gradient of the slab,and the gravity of the slab track,a dynamic model for a high-speed train that runs along the CRTS Ⅲ slab track on subgrade is developed by a nonlinear coupled way in Abaqus.Findings-The results are as follows:(1)The upward transmission of the periodic deformation of the slab causes periodic track irregularity.(2)Because of the geometric constraint of limiting structures,the maximum bending stresses of the slab occur near the end of the slab under positive temperature gradients,but in the middle of the slab under negative temperature gradients.(3)The periodic deformation of the slab can induce periodic changes in the interlayer stiffness and contact status,leading to a large vibration of the slab.Because of the vibration-reduction capacity of the fastener and the larger mass of the concrete base,the accelerations of both the slab and concrete base are far less than the acceleration of the rail.Originality/value-This study reveals the influence mechanism of temperature gradient-induced periodic deformation in the dynamic responses of the train-track system,and it also provides a guide for the safe service of CRTS Ⅲ slab track.
文摘BACKGROUND： Glutathione, as an in vivo free radical scavenger, plays an important role in the anti-oxidation defense mechanism in patients with acute cerebral infarction. OBJECTIVE： To observe the relationship between the levels of glutathione （GSH） and malonaldehyde （MDA）, the metabolite of lipid peroxidation, in erythrocyte and deformation index of erythrocyte in patients at various periods following acute cerebral infarction. DESIGN： Controlled observation.SETTING： Qilu Hospital of Shandong University and Institute of Cerebrovascular Disease of Qingdao Medical College. PARTICIPANTS： We chose 98 inpatients with acute cerebral infarction from Department of Neurology, Qilu Hospital of Shandong University from January to December 2000 , serving as cerebral infarction group, including 50 male and 48 female, with mean age of （62±7）years. There were 23 cases found on the 1^st day after onset; 25 cases on the 3^rd day after onset; 25 cases on the 7^th day after onset; 25 cases on the 14th days after onset, and they were all confirmed by craniocerebral CT or MRI. Another 30 homeochronous inpatients with neurosis, cervical syndrome, lumbar intervertebral disc herniation and motor neuron disease were chosen as control group, including 20 male and 10 female, with mean age of （52±8）years . There was no significant difference in age and gender distribution between two groups （P 〉 0.05）. Patients in the two groups were informed of detected index.METHODS：①Ulnar venous blood was chosen from the patients who were fasted on the 1^st, 3^rd,7^th and 14^th days after onset. Deformation index of erythrocyte was measured with BL88-CKX laser diffraction erythrocyte deformeter and photographing was performed. GSH level in erythrocyte was measured with DTNB assay introduced by Beu-tler. MDA level in erythrocyte was measured with modified thiobarbituric acid colorimetric method.②At each sample collecting , according to the criteria accepted by the Fourth National Conference of Cerebrovascular Disease, intergrant of neurologic impairment 〈 15 points was regarded as mild （n=46）, 15 to 30 points as moderate （n=40）and, 〉 30 points as severe （n=12）. ③ t test was used to compare data between two groups , and linear correlation analysis was used in relationship analysis among indexes. MAIN OUTCOME MEASURES ：① Comparison of erythrocyte GSH and MDA levels and deformation index of erythrocyte at various periods between patients with acute cerebral infarction and controls. ②Correlation of erythrocyte GSH level with erythrocyte MDA level and with deformation index of erythrocyte in patients with cerebral infarction . ③ Relationship between erythrocyte GSH level and severity of disease in patients with acute cerebral infarction. RESULTS： Totally 98 patients with acute cerebral infarction and 30 controls all entered the stage of result analysis. ① Erythrocyte GSH level and deformation index of erythrocyte were lower on the 1^st, 3^rd, 7^th and 14^th days after onset in cerebral infarction group than in control group （P 〈 0.05-0.01）, and erythrocyte MDA level was significantly higher in cerebral infarction group than in control group （P 〈 0.05-0.01）. The three indexes changed most significantly on day 3 after onset in patients, and began to recover or decrease on day 7 after onset and inclined to be normal on day 14 after onset. ② Erythrocyte GSH level was significantly negatively correlated with erythrocyte MDA level in patients with acute cerebral infarction on the 1^st, 3^rd, 7^th and 14^th days after onset （r=-0.534, -0.713, -0.645, -0.656, respectively, P 〈 0.05-0.01 ） ,and significantly positively correlated with erythrocyte deformation index （t-=0.502, 0.560, 0.455, 0.504, respectively, P 〈 0.05）. ③Erythrocyte GSH level was significantly lower in moderate or severe patients with acute cerebral infarction than in mild patients[（0.215±0.088）,（0.192±0.102）, （0.281±0.090） g/L, P〈 0.05]. CONCLUSION：①Erythrocyte GSH and MDA levels and deformation index of erythrocyte change significantly on the 3^rd day following acute cerebral infarction. Index detection results gradually tended to be normal on from the 7^th day to 14^th days day after onset. ② Change of erythrocyte GSH level can reflect the severity of disease of patients with acute cerebral infarction.③Decrease of erythrocyte GSH level in patients with acute cerebral infarction is one of reasons that result in the decrease of deformation ability of erythrocyte.
