In this study,the concrete cone capacity,concrete cone angle,and load–displacement response of cast-in headed anchors in geopolymer concrete are explored using numerical analyses.The concrete damaged plasticity(CDP)m...In this study,the concrete cone capacity,concrete cone angle,and load–displacement response of cast-in headed anchors in geopolymer concrete are explored using numerical analyses.The concrete damaged plasticity(CDP)model in ABAQUS is used to simulate the behavior of concrete substrates.The tensile behavior of anchors in geopolymer concrete is compared with that in normal concrete as well as that predicted by the linear fracture mechanics(LFM)and concrete capacity design(CCD)models.The results show that the capacity of the anchors in geopolymer concrete is 30%–40%lower than that in normal concrete.The results also indicate that the CCD model overestimates the capacity of the anchors in geopolymer concrete,whereas the LFM model provides a much more conservative prediction.The extent of the difference between the predictions by the numerical analysis and those of the above prediction models depends on the effective embedment depth of the anchor and the anchor head size.The influence of concrete surface cracking on the capacity of the anchor is shown to depend on the location of the crack and the effective embedment depth.The influence of the anchor head profile on the tensile capacity of the anchors is found to be insignificant.展开更多
Background We investigated the effects of using large-diameter femoral heads in total hip prostheses on early postoperative gait restoration in patients undergoing total hip arthroplasty （THA）. Methods We collected ...Background We investigated the effects of using large-diameter femoral heads in total hip prostheses on early postoperative gait restoration in patients undergoing total hip arthroplasty （THA）. Methods We collected data for 19 primary THAs using 28-mm metal-on-polyethylene heads （conventional group） and for 12 THAs （BHR group） using metal-on-metal femoral heads with an average size of 45 mm （range, 40-49mm）. All patients had unilateral femoral head avascular necrosis. All patients underwent Harris Hip Scores evaluation and gait analysis with the IDEEA device at the same 3 time points which were before surgery and then at 1 month and again at 3 months after surgery, and the parameters measured were walking speed, stride length （SL）, single limb support （SLS）, cycle duration （CD）, and swing power （SP）. Harris Hip Scores and gait analysis parameters for both groups were compared. Results Intraclass comparison indicated that Harris Hip Scores, speed scores, and gait parameter measures in both groups improved significantly with the passage of time; Interclass comparison showed no significance between Harristm postop - HarriSpreop and Harris3m postop- HarriSpreop in both groups. The speed in the BHR group at 1 month and at 3 months after surgery was significantly higher than that of conventional group. At 1 month after surgery, each mean for SLnormal - SLaffected, （SLSnormal - SLSaffected）/CD, and SPnormal - SPaffected in the BHR group was significantly lower than that for the conventional group. At 3 months after surgery, the differences between means for both groups for SLnormal - SLaffected, （SLSnormal- SLSaffected）/CD, and SPnormal - SPaffected were not significant, but the mean of SPnorrnal - SPaffected in the BHR group was significantly lower than that in the conventional group. Conclusions Our data suggest that large-diameter femoral heads in THA provide better early gait restoration than conventional-size femoral heads.展开更多
Phrynocephalus guinanensis has sexual dimorphism in abdominal coloration, but its ontogenetic development of sexual size dimorphism （SSD） is unknown. Using mark-recapture data during four days each year from August ...Phrynocephalus guinanensis has sexual dimorphism in abdominal coloration, but its ontogenetic development of sexual size dimorphism （SSD） is unknown. Using mark-recapture data during four days each year from August from 2014 to 2016, we investigated the development of sex ratios, SSD, sex-specific survivorship and growth rates in a population of P guinanensis. Our results indicated that the sex ratio of males to females was 1：2.8. Males had a lower survival rate （6%） than females （14%） across the age range from hatchling to adult, which supported the discovered female-biased sex ratio potentially associated with the low survival rate of males between hatchlings and juveniles. Male-biased SSD in tail length and head width existed in adults rather than in hatchling or juvenile lizards. The growth rates in body dimensions were undistinguishable between the sexes during the age from hatchling to juvenile, but the growth rate in head length from juvenile to adult was significantly larger in males than females. Average growth rate of all morphological measurements from hatchling to juvenile were larger compared with corresponding measurements from juvenile to adult, but only being significant in tail length, head width, abdomen length in females and snout-vent length in males. We provided a case study to strengthen our understanding of the important life history traits on how a viviparous lizard population can survive and develop their morphology in cold climates.展开更多
文摘In this study,the concrete cone capacity,concrete cone angle,and load–displacement response of cast-in headed anchors in geopolymer concrete are explored using numerical analyses.The concrete damaged plasticity(CDP)model in ABAQUS is used to simulate the behavior of concrete substrates.The tensile behavior of anchors in geopolymer concrete is compared with that in normal concrete as well as that predicted by the linear fracture mechanics(LFM)and concrete capacity design(CCD)models.The results show that the capacity of the anchors in geopolymer concrete is 30%–40%lower than that in normal concrete.The results also indicate that the CCD model overestimates the capacity of the anchors in geopolymer concrete,whereas the LFM model provides a much more conservative prediction.The extent of the difference between the predictions by the numerical analysis and those of the above prediction models depends on the effective embedment depth of the anchor and the anchor head size.The influence of concrete surface cracking on the capacity of the anchor is shown to depend on the location of the crack and the effective embedment depth.The influence of the anchor head profile on the tensile capacity of the anchors is found to be insignificant.
文摘Background We investigated the effects of using large-diameter femoral heads in total hip prostheses on early postoperative gait restoration in patients undergoing total hip arthroplasty （THA）. Methods We collected data for 19 primary THAs using 28-mm metal-on-polyethylene heads （conventional group） and for 12 THAs （BHR group） using metal-on-metal femoral heads with an average size of 45 mm （range, 40-49mm）. All patients had unilateral femoral head avascular necrosis. All patients underwent Harris Hip Scores evaluation and gait analysis with the IDEEA device at the same 3 time points which were before surgery and then at 1 month and again at 3 months after surgery, and the parameters measured were walking speed, stride length （SL）, single limb support （SLS）, cycle duration （CD）, and swing power （SP）. Harris Hip Scores and gait analysis parameters for both groups were compared. Results Intraclass comparison indicated that Harris Hip Scores, speed scores, and gait parameter measures in both groups improved significantly with the passage of time; Interclass comparison showed no significance between Harristm postop - HarriSpreop and Harris3m postop- HarriSpreop in both groups. The speed in the BHR group at 1 month and at 3 months after surgery was significantly higher than that of conventional group. At 1 month after surgery, each mean for SLnormal - SLaffected, （SLSnormal - SLSaffected）/CD, and SPnormal - SPaffected in the BHR group was significantly lower than that for the conventional group. At 3 months after surgery, the differences between means for both groups for SLnormal - SLaffected, （SLSnormal- SLSaffected）/CD, and SPnormal - SPaffected were not significant, but the mean of SPnorrnal - SPaffected in the BHR group was significantly lower than that in the conventional group. Conclusions Our data suggest that large-diameter femoral heads in THA provide better early gait restoration than conventional-size femoral heads.
基金supported by the National Natural Science Foundation of China (31372183, 31772447, 31471988)
文摘Phrynocephalus guinanensis has sexual dimorphism in abdominal coloration, but its ontogenetic development of sexual size dimorphism （SSD） is unknown. Using mark-recapture data during four days each year from August from 2014 to 2016, we investigated the development of sex ratios, SSD, sex-specific survivorship and growth rates in a population of P guinanensis. Our results indicated that the sex ratio of males to females was 1：2.8. Males had a lower survival rate （6%） than females （14%） across the age range from hatchling to adult, which supported the discovered female-biased sex ratio potentially associated with the low survival rate of males between hatchlings and juveniles. Male-biased SSD in tail length and head width existed in adults rather than in hatchling or juvenile lizards. The growth rates in body dimensions were undistinguishable between the sexes during the age from hatchling to juvenile, but the growth rate in head length from juvenile to adult was significantly larger in males than females. Average growth rate of all morphological measurements from hatchling to juvenile were larger compared with corresponding measurements from juvenile to adult, but only being significant in tail length, head width, abdomen length in females and snout-vent length in males. We provided a case study to strengthen our understanding of the important life history traits on how a viviparous lizard population can survive and develop their morphology in cold climates.
