Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects o...Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.展开更多
A new beech and self-tapping screw composite dowel is proposed and studied,its performance being compared with that of beech dowels and self-tapping screws alone.The single shear performance of components connected by...A new beech and self-tapping screw composite dowel is proposed and studied,its performance being compared with that of beech dowels and self-tapping screws alone.The single shear performance of components connected by composite dowels was tested.Results show that the dowels are a good choice for components requiring high stiffness.Screws remain a good choice for components requiring excellent seismic performance.Combination group presents similar maximum load stiffness to those of composite dowels,but other ductility parameters are superior for composite dowels.The best connection mode was provided by two composite dowels.Based on connecting two points,structural elements with two composite dowels showed much better load bearing ability than when joined by two beech dowels or by two self-tapping screws separately.The structural element with two composite dowels not only presented better initial stiffness,but also exhibited a better ductility coeffi-cient and less energy consumption.So,the composite dowels can be used for beam column connection,dowel laminated timber,and restoration or enhancement of ancient buildings.展开更多
Introduction: An observation was made that when removing self-tapping cortical screws from patients bones, stripping or shearing of the head of the screw occurred more often in screws whose cutting flutes sat in corti...Introduction: An observation was made that when removing self-tapping cortical screws from patients bones, stripping or shearing of the head of the screw occurred more often in screws whose cutting flutes sat in cortical bone compared with screws that had penetrated the distal cortex with flutes exposed. Method: A model was designed to simulate screws with their cutting flutes either in contact with cortical bone or deep to cortical bone. Screws were grouped depending on the location of their cutting flutes and removal torque was measured. Results: Eighteen screws were included in final analysis. There was a statistically significant difference in average initial removal torque and average maximal removal torque with screws with their cutting flutes in substrate requiring significantly more torque to remove. Conclusion: We conclude that self-tapping cortical screws whose cutting flutes sit in cortical substrate require more torque to remove and are therefore more likely to fail. This finding may be used as a guide in pre-operative planning for removal of metalwork from patients.展开更多
The scanning electron microscope (SEM) results of bone interface of titanium-coated 317L plate screw are reported in this article. 317L plate screw had a rough surface composed of sprayed pure titanium which formed a ...The scanning electron microscope (SEM) results of bone interface of titanium-coated 317L plate screw are reported in this article. 317L plate screw had a rough surface composed of sprayed pure titanium which formed a bone/metal interface in biointegration after implanted into the mandible of dog. Though a bone/metal interface in osseointegration was also formed on the surface of uncoated 317L plate screw after implantation, a smal1 space was seen between the bone and surface of the screw, indicating that the tissue compatibility of titanium-coated 317L plate screw may be better than that of the non-coated screw.展开更多
目的探讨空心无头加压螺钉钛缆张力带内固定术对髌骨骨折(patellar fracture,PF)患者并发症及膝关节功能的影响。方法选取2020年6月至2022年2月平度市第三人民医院收治的92例PF患者作为研究对象,按照随机数字表法分为对照组与观察组,每...目的探讨空心无头加压螺钉钛缆张力带内固定术对髌骨骨折(patellar fracture,PF)患者并发症及膝关节功能的影响。方法选取2020年6月至2022年2月平度市第三人民医院收治的92例PF患者作为研究对象,按照随机数字表法分为对照组与观察组,每组46例。对照组予以克氏针钢丝张力带内固定术治疗,观察组予以空心无头加压螺钉钛缆张力带固定术治疗。比较两组围手术期指标、临床疗效、并发症发生情况、疼痛情况[视觉模拟评分法(visual analogue scale,VAS)评分]、膝关节功能及生命质量[生命质量综合评定问卷(generic quality of life inventory-74,GQOLI-74)评分]。结果两组术中失血量、手术时间及住院时间比较差异无统计学意义;观察组下床活动时间短于对照组,差异有统计学意义(P<0.05)。观察组治疗总有效率为95.65%,高于对照组的82.61%,差异有统计学意义(P<0.05)。观察组并发症发生率为4.35%,低于对照组的19.57%,差异有统计学意义(P<0.05)。治疗后,观察组VAS评分低于对照组,差异有统计学意义(P<0.05)。治疗后,观察组疼痛程度、工作能力、肌萎缩程度、关节活动范围、辅助物使用及积液情况评分均高于对照组,差异有统计学意义(P<0.05)。治疗后,观察组物质生活、社会功能、生理及心理功能评分均高于对照组,差异有统计学意义(P<0.05)。结论空心无头加压螺钉钛缆张力带内固定术治疗PF疗效显著,可缩短患者术后恢复时间,减少并发症发生,减轻术后疼痛,促进膝关节功能恢复,提高患者生命质量,值得临床推广应用。展开更多
基金funded by the National Natural Science Foundation of China (32160348)Forestry Science and Technology Research Project of Guizhou Forestry Bureau (J[2022]21 and[2020]C14)+1 种基金Department Program of Guizhou Province ([2020]1Y128)the Cultivation Project of Guizhou University of China ([2019]37).
文摘Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.
基金The authors are grateful for the support of the National Natural Science Foundation of China(Grant No.31901252)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180276)+3 种基金Jiangsu Planned Projects for Postdoctoral Research Funds(Grant No.2020Z075)the Science and Technology Program of Jiangsu Housing and Construction Department(Grant Nos.2018ZD118 and 2020ZD29)Qing Lan Project of Jiangsu,the Yangzhou Science and Technology Project(Grant No.SGH2020010040)Yangzhou Polytechnic Institute Project(Grant No.2019xjzk007).
文摘A new beech and self-tapping screw composite dowel is proposed and studied,its performance being compared with that of beech dowels and self-tapping screws alone.The single shear performance of components connected by composite dowels was tested.Results show that the dowels are a good choice for components requiring high stiffness.Screws remain a good choice for components requiring excellent seismic performance.Combination group presents similar maximum load stiffness to those of composite dowels,but other ductility parameters are superior for composite dowels.The best connection mode was provided by two composite dowels.Based on connecting two points,structural elements with two composite dowels showed much better load bearing ability than when joined by two beech dowels or by two self-tapping screws separately.The structural element with two composite dowels not only presented better initial stiffness,but also exhibited a better ductility coeffi-cient and less energy consumption.So,the composite dowels can be used for beam column connection,dowel laminated timber,and restoration or enhancement of ancient buildings.
文摘Introduction: An observation was made that when removing self-tapping cortical screws from patients bones, stripping or shearing of the head of the screw occurred more often in screws whose cutting flutes sat in cortical bone compared with screws that had penetrated the distal cortex with flutes exposed. Method: A model was designed to simulate screws with their cutting flutes either in contact with cortical bone or deep to cortical bone. Screws were grouped depending on the location of their cutting flutes and removal torque was measured. Results: Eighteen screws were included in final analysis. There was a statistically significant difference in average initial removal torque and average maximal removal torque with screws with their cutting flutes in substrate requiring significantly more torque to remove. Conclusion: We conclude that self-tapping cortical screws whose cutting flutes sit in cortical substrate require more torque to remove and are therefore more likely to fail. This finding may be used as a guide in pre-operative planning for removal of metalwork from patients.
文摘The scanning electron microscope (SEM) results of bone interface of titanium-coated 317L plate screw are reported in this article. 317L plate screw had a rough surface composed of sprayed pure titanium which formed a bone/metal interface in biointegration after implanted into the mandible of dog. Though a bone/metal interface in osseointegration was also formed on the surface of uncoated 317L plate screw after implantation, a smal1 space was seen between the bone and surface of the screw, indicating that the tissue compatibility of titanium-coated 317L plate screw may be better than that of the non-coated screw.
文摘目的探讨空心无头加压螺钉钛缆张力带内固定术对髌骨骨折(patellar fracture,PF)患者并发症及膝关节功能的影响。方法选取2020年6月至2022年2月平度市第三人民医院收治的92例PF患者作为研究对象,按照随机数字表法分为对照组与观察组,每组46例。对照组予以克氏针钢丝张力带内固定术治疗,观察组予以空心无头加压螺钉钛缆张力带固定术治疗。比较两组围手术期指标、临床疗效、并发症发生情况、疼痛情况[视觉模拟评分法(visual analogue scale,VAS)评分]、膝关节功能及生命质量[生命质量综合评定问卷(generic quality of life inventory-74,GQOLI-74)评分]。结果两组术中失血量、手术时间及住院时间比较差异无统计学意义;观察组下床活动时间短于对照组,差异有统计学意义(P<0.05)。观察组治疗总有效率为95.65%,高于对照组的82.61%,差异有统计学意义(P<0.05)。观察组并发症发生率为4.35%,低于对照组的19.57%,差异有统计学意义(P<0.05)。治疗后,观察组VAS评分低于对照组,差异有统计学意义(P<0.05)。治疗后,观察组疼痛程度、工作能力、肌萎缩程度、关节活动范围、辅助物使用及积液情况评分均高于对照组,差异有统计学意义(P<0.05)。治疗后,观察组物质生活、社会功能、生理及心理功能评分均高于对照组,差异有统计学意义(P<0.05)。结论空心无头加压螺钉钛缆张力带内固定术治疗PF疗效显著,可缩短患者术后恢复时间,减少并发症发生,减轻术后疼痛,促进膝关节功能恢复,提高患者生命质量,值得临床推广应用。
