OBJECTIVE: The aim of this study was to evaluate the effectiveness and safety of stem cell transplantation for spinal cord injury(SCI).DATA SOURCES: PubM ed, EMBASE, Cochrane, China National Knowledge Infrastructu...OBJECTIVE: The aim of this study was to evaluate the effectiveness and safety of stem cell transplantation for spinal cord injury(SCI).DATA SOURCES: PubM ed, EMBASE, Cochrane, China National Knowledge Infrastructure, China Science and Technology Journal, Wanfang, and Sino Med databases were systematically searched by computer to select clinical randomized controlled trials using stem cell transplantation to treat SCI, published between each database initiation and July 2016. DATA SELECTION: Randomized controlled trials comparing stem cell transplantation with rehabilitation treatment for patients with SCI. Inclusion criteria:(1) Patients with SCI diagnosed according to the American Spinal Injury Association(ASIA) International standards for neurological classification of SCI;(2) patients with SCI who received only stem cell transplantation therapy or stem cell transplantation combined with rehabilitation therapy;(3) one or more of the following outcomes reported: outcomes concerning neurological function including sensory function and locomotor function, activities of daily living, urination functions, and severity of SCI or adverse effects. Studies comprising patients with complications, without full-text, and preclinical animal models were excluded. Quality of the included studies was evaluated using the Cochrane risk of bias assessment tool and Rev Man V5.3 software, provided by the Cochrane Collaboration, was used to perform statistical analysis. OUTCOME MEASURES: ASIA motor score, ASIA light touch score, ASIA pinprick score, ASIA impairment scale grading improvement rate, activities of daily living score, residual urine volume, and adverse events.RESULTS: Ten studies comprising 377 patients were included in the analysis and the overall risk of bias was relatively low level. Four studies did not detail how random sequences were generated, two studies did not clearly state the blinding outcome assessment, two studies lacked blinding outcome assessment, one study lacked follow-up information, and four studies carried out selective reporting. Compared with rehabilitation therapy, stem cell transplantation significantly increased the lower limb light touch score(odds ratio(OR) = 3.43, 95% confidence interval(CI): 0.01 – 6.86, P = 0.05), lower limb pinprick score(OR = 3.93, 95%CI: 0.74 – 7.12, P = 0.02), ASI grading rate(relative risk(RR) = 2.95, 95%CI: 1.64 – 5.29, P = 0.0003), and notably reduced residual urine volume(OR = –8.10, 95%CI: –15.09 to –1.10, P = 0.02). However, stem cell transplantation did not significantly improve motor score(OR = 1.89, 95%CI: –0.25 to 4.03, P = 0.08) or activities of daily living score(OR = 1.12, 95%CI: –1.17 to 4.04, P = 0.45). Furthermore, stem cell transplantation caused a high rate of mild adverse effects(RR = 14.49, 95%CI: 5.34 – 34.08, P 〈 0.00001); however, these were alleviated in a short time. CONCLUSION: Stem cell transplantation was determined to be an efficient and safe treatment for SCI and simultaneously improved sensory and bladder functions. Although associated minor and temporary adverse effects were observed with transplanted stem cells, spinal cord repair and axon remyelination were apparent. More randomized controlled trials with larger sample sizes and longer follow-up times are needed to further validate the effectiveness of stem cell transplantation in the treatment of SCI.展开更多
The hot deformation and dynamic recrystallization(DRX)behaviors of 7055 aluminum alloy were studied at temperatures of 390−470℃ and strain rates of 0.01−1 s^(−1).A low DRX fraction between 1% and 13% was observed by ...The hot deformation and dynamic recrystallization(DRX)behaviors of 7055 aluminum alloy were studied at temperatures of 390−470℃ and strain rates of 0.01−1 s^(−1).A low DRX fraction between 1% and 13% was observed by using EBSD technique.A modified JMAK-type DRX model was proposed for such low DRX fraction problems.The model was used together with commercial FEM software DEFORM-3D to simulate the hot compression of 7055 aluminum alloy.There was a good agreement between experimental and predicted DRX fractions and grain size with an average absolute relative error(AARE)of 13.7% and 6.3%,respectively.In order to further verify the validity of the proposed model,the model was also used to simulate DRX in industrial hot rolling of 7055 aluminum alloys.The results showed that the distribution of DRX fraction was inhomogeneous,and agreed with experimental observations.展开更多
The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite(Ti42Zr22V14-Cu5Be17)prepared by copper mould casting were analyzed at different normal loads under the dry condition and...The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite(Ti42Zr22V14-Cu5Be17)prepared by copper mould casting were analyzed at different normal loads under the dry condition and rainwater.The results showed that the average value of the frictional coefficients and micro-hardness ascended with increasing the normal load,while the wear rate showed a trend of decline under the dry condition.The electrochemical test results showed that the surface of samples was pitting corroded in the rainwater.The matrices were corroded first.Then the dendrites were exposed,leading to the damage of the surface.Both the frictional coefficients and wear rate of the composite in the rainwater were larger than those under the dry condition,primarily owing to the corrosion of chloride ions on the worn surface.The wear mechanisms of composites were mainly adhesive wear,accompanied by the abrasive wear under the dry condition and corrosive wear in the rainwater.The composites have higher wear resistance both under the dry condition and rainwater due to the lower wear rate.展开更多
基金supported by the National Natural Science Foundation of China,No.81273775
文摘OBJECTIVE: The aim of this study was to evaluate the effectiveness and safety of stem cell transplantation for spinal cord injury(SCI).DATA SOURCES: PubM ed, EMBASE, Cochrane, China National Knowledge Infrastructure, China Science and Technology Journal, Wanfang, and Sino Med databases were systematically searched by computer to select clinical randomized controlled trials using stem cell transplantation to treat SCI, published between each database initiation and July 2016. DATA SELECTION: Randomized controlled trials comparing stem cell transplantation with rehabilitation treatment for patients with SCI. Inclusion criteria:(1) Patients with SCI diagnosed according to the American Spinal Injury Association(ASIA) International standards for neurological classification of SCI;(2) patients with SCI who received only stem cell transplantation therapy or stem cell transplantation combined with rehabilitation therapy;(3) one or more of the following outcomes reported: outcomes concerning neurological function including sensory function and locomotor function, activities of daily living, urination functions, and severity of SCI or adverse effects. Studies comprising patients with complications, without full-text, and preclinical animal models were excluded. Quality of the included studies was evaluated using the Cochrane risk of bias assessment tool and Rev Man V5.3 software, provided by the Cochrane Collaboration, was used to perform statistical analysis. OUTCOME MEASURES: ASIA motor score, ASIA light touch score, ASIA pinprick score, ASIA impairment scale grading improvement rate, activities of daily living score, residual urine volume, and adverse events.RESULTS: Ten studies comprising 377 patients were included in the analysis and the overall risk of bias was relatively low level. Four studies did not detail how random sequences were generated, two studies did not clearly state the blinding outcome assessment, two studies lacked blinding outcome assessment, one study lacked follow-up information, and four studies carried out selective reporting. Compared with rehabilitation therapy, stem cell transplantation significantly increased the lower limb light touch score(odds ratio(OR) = 3.43, 95% confidence interval(CI): 0.01 – 6.86, P = 0.05), lower limb pinprick score(OR = 3.93, 95%CI: 0.74 – 7.12, P = 0.02), ASI grading rate(relative risk(RR) = 2.95, 95%CI: 1.64 – 5.29, P = 0.0003), and notably reduced residual urine volume(OR = –8.10, 95%CI: –15.09 to –1.10, P = 0.02). However, stem cell transplantation did not significantly improve motor score(OR = 1.89, 95%CI: –0.25 to 4.03, P = 0.08) or activities of daily living score(OR = 1.12, 95%CI: –1.17 to 4.04, P = 0.45). Furthermore, stem cell transplantation caused a high rate of mild adverse effects(RR = 14.49, 95%CI: 5.34 – 34.08, P 〈 0.00001); however, these were alleviated in a short time. CONCLUSION: Stem cell transplantation was determined to be an efficient and safe treatment for SCI and simultaneously improved sensory and bladder functions. Although associated minor and temporary adverse effects were observed with transplanted stem cells, spinal cord repair and axon remyelination were apparent. More randomized controlled trials with larger sample sizes and longer follow-up times are needed to further validate the effectiveness of stem cell transplantation in the treatment of SCI.
基金the financial supports from the National Key Research and Development Program of China(No.2016YFB-0300901)the National Natural Science Foundation of China(No.51871033)+1 种基金the Chongqing Research Program of Basic Research and Frontier Technology,China(No.cstc2017jcyjAX0245)the Venture&Innovation Support Program for Chongqing Overseas Returnees,China(No.cx2018002).
文摘The hot deformation and dynamic recrystallization(DRX)behaviors of 7055 aluminum alloy were studied at temperatures of 390−470℃ and strain rates of 0.01−1 s^(−1).A low DRX fraction between 1% and 13% was observed by using EBSD technique.A modified JMAK-type DRX model was proposed for such low DRX fraction problems.The model was used together with commercial FEM software DEFORM-3D to simulate the hot compression of 7055 aluminum alloy.There was a good agreement between experimental and predicted DRX fractions and grain size with an average absolute relative error(AARE)of 13.7% and 6.3%,respectively.In order to further verify the validity of the proposed model,the model was also used to simulate DRX in industrial hot rolling of 7055 aluminum alloys.The results showed that the distribution of DRX fraction was inhomogeneous,and agreed with experimental observations.
基金Item Sponsored by National Natural Science Foundation of China(51371122,51401141)Program for the Innovative Talents of Higher Learning Institutions of Shanxi Province of China(2013)Youth Science Foundation of Shanxi Province of China(2014021017-3)
文摘The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite(Ti42Zr22V14-Cu5Be17)prepared by copper mould casting were analyzed at different normal loads under the dry condition and rainwater.The results showed that the average value of the frictional coefficients and micro-hardness ascended with increasing the normal load,while the wear rate showed a trend of decline under the dry condition.The electrochemical test results showed that the surface of samples was pitting corroded in the rainwater.The matrices were corroded first.Then the dendrites were exposed,leading to the damage of the surface.Both the frictional coefficients and wear rate of the composite in the rainwater were larger than those under the dry condition,primarily owing to the corrosion of chloride ions on the worn surface.The wear mechanisms of composites were mainly adhesive wear,accompanied by the abrasive wear under the dry condition and corrosive wear in the rainwater.The composites have higher wear resistance both under the dry condition and rainwater due to the lower wear rate.