In this paper,the phenomena of Mg_(2)Sn-induced Sn whisker growth were explored on the surfaces of Mg/Sn/Mg ultrasonic-assisted soldering joints after aging treatment.The in-situ observation and thermal analysis confi...In this paper,the phenomena of Mg_(2)Sn-induced Sn whisker growth were explored on the surfaces of Mg/Sn/Mg ultrasonic-assisted soldering joints after aging treatment.The in-situ observation and thermal analysis confirmed that the formation and the corrosion of Mg_(2)Sn nanoparticles were the dominant reason of Sn whisker growth.The Mg_(2)Sn accumulation at the grain boundaries would pin the dislocation slip and affect the continuity of whisker growth,and the boundary angle would thus play a decisive role in the growth shape of Sn whiskers due to the pining effect of Mg_(2)Sn.This study might be conducive to elucidating the growth behavior of Sn whiskers and provide the exploration strategy to further improve the bonding strength of Mg/Sn/Mg ultrasonic-assisted soldering joints.展开更多
Many factors influence the fatigue and crack growth behavior of welded joints. Some structures often undergo fairly large static loading before they enter service or variable amplitude cyclic loading when they are in ...Many factors influence the fatigue and crack growth behavior of welded joints. Some structures often undergo fairly large static loading before they enter service or variable amplitude cyclic loading when they are in service. The combined effect of both applied stress and high initial residual stress is expected to cause the residual stresses relaxation. Only a few papers seem to deal with appropriate procedures for fatigue analysis and crack growth by considering the combined effect of variable amplitude cyclic loading with residual stresses relaxation. In this article, some typical welded connections in ship-shaped structures are investigated with 3-D elastic-plastic finite element analysis. The effect of residual stress relaxation, initial residual stress, and the applied load after variable amplitude cyclic loading is revealed, and a formula for predicting the residual stress at hot spot quantitatively is proposed. Based on the formula, an improved fatigue procedure is introduced. Moreover, crack growth of typical weld joints considering residual stresses relaxation is studied.展开更多
Joint toxicity of Beauveria bassiana and two insect growth regulators, methoxyfenozide and hexaflumuron, on beet annywonn larvae, Spodoptera exigua （ Htthner）, were investigated. An obvious synergism effect of the t...Joint toxicity of Beauveria bassiana and two insect growth regulators, methoxyfenozide and hexaflumuron, on beet annywonn larvae, Spodoptera exigua （ Htthner）, were investigated. An obvious synergism effect of the two insect growth regulators with B. beauveria was observed. When the insect growth regulators at LC50 concentrations （25 × 10^-6 g/L for methoxyfenozide and 1 000 × 10^ -6 g/L for hexaflumuren） were mixed with B. bassiana at the volume ratio of 4： 1, the mixtures achieved the best efficacy. The co-toxicity co-efficient （CTC） of methexyfenozide and B. bass/ana was 285, and that of hexaflumuron and B. bass/ana was 208. Scanning electron microscope observation of the longitudinal section of S. exigua revealed obviously different patterns of integument in different treatment groups.展开更多
Objective: The aim of the study was to evaluate the effect of platelet rich growth factors (PRGFs) in treatment of temporomandibular joint disc displacement. Materials and Methods: The study subjects included 8 female...Objective: The aim of the study was to evaluate the effect of platelet rich growth factors (PRGFs) in treatment of temporomandibular joint disc displacement. Materials and Methods: The study subjects included 8 females having bilateral anterior disc displacement with reduction and 1 female having bilateral anterior disc displacement without reduction with the age range between 20 - 35 years. The process of obtaining PRGFs was carried out following the Anitua Technique. Results: Clinical parameters of Interincisal distance, Lateral excursion of mandible using digital caliper in millimeters and Visual Analogue Scale (VAS 0/10) for pain intensity score were used. All of these parameters were running through the intervals of two, four, and eight weeks till the end of the follow-up period at twenty-six weeks (six months). The participated patients showed the clinical improvement in the different clinical statuses such as interincisal distance;lateral excursion of mandible and Pain Score. Conclusion: the study reported early efficacy of PRGFs after the arthrocentesis of the joint in treatment of TMJ disc displacement, and according to our results, the injection of PRGFs could be a possible alternative treatment for patients who did not respond to standard treatment.展开更多
目的观察火针联合董氏奇穴针刺治疗肩袖损伤的临床疗效及对关节功能及血清前列腺素E_(2)(prostaglandin E_(2),PGE_(2))和转化生长因子-β1(transforming growth factor-β1,TGF-β1)的影响。方法将100例肩袖损伤患者随机分为对照组(50...目的观察火针联合董氏奇穴针刺治疗肩袖损伤的临床疗效及对关节功能及血清前列腺素E_(2)(prostaglandin E_(2),PGE_(2))和转化生长因子-β1(transforming growth factor-β1,TGF-β1)的影响。方法将100例肩袖损伤患者随机分为对照组(50例)和观察组(50例)。对照组予以电针联合董氏奇穴针刺治疗,观察组予以火针联合董氏奇穴针刺治疗。检测视觉模拟量表(visual analog scale,VAS)和美国加利福尼亚大学洛杉矶分校(University of California,Los Angeles,UCLA)肩关节评分、肩关节活动度(range of motion,ROM)及血清PGE_(2)和TGF-β1水平。结果观察组总有效率高于对照组(P<0.05)。治疗后及4周随访时,两组VAS评分及血清PGE_(2)和TGF-β1水平均低于治疗前(P<0.05),且观察组均低于对照组(P<0.05);两组UCLA肩关节评分和肩关节ROM均高于治疗前(P<0.05),且观察组均高于对照组(P<0.05)。4周随访时,两组VAS评分、UCLA肩关节评分、肩关节ROM及血清PGE_(2)和TGF-β1水平与治疗后比较差异无统计系意义(P>0.05)。治疗后血清PGE_(2)、TGF-β1水平与VAS评分呈正相关,与UCLA肩关节评分呈负相关。结论火针和电针联合董氏奇穴针刺治疗肩袖损伤均可缓解疼痛、改善肩关节功能,但火针优于电针,其机制可能与降低血清PGE_(2)和TGF-β1水平有关。展开更多
Double edge notched tensile （DENT） tests were carried out to investigate the slow crack growth （SCG） behavior of PESO welded joints. Efforts were made to acquire creep fracture parameters which can characterize cr...Double edge notched tensile （DENT） tests were carried out to investigate the slow crack growth （SCG） behavior of PESO welded joints. Efforts were made to acquire creep fracture parameters which can characterize creep resistance. Results show that creep compliance indicates an ascending trend with the increase of applied stress. A global creep load parameter is obtained. It has a linear relationship with fkacture time in logarithmic coordinate system and helps to predict the fracture time at any applied load.展开更多
基金supported by Science and Technology Planning Project of Shenzhen (Grant No. JCYJ201908 09161213154)Xiamen Youth Innovation Fund Project (Grant No. 3502Z20206026)Academy-level Project of Xiamen City University (Grant No.KYKJ2019-4)。
文摘In this paper,the phenomena of Mg_(2)Sn-induced Sn whisker growth were explored on the surfaces of Mg/Sn/Mg ultrasonic-assisted soldering joints after aging treatment.The in-situ observation and thermal analysis confirmed that the formation and the corrosion of Mg_(2)Sn nanoparticles were the dominant reason of Sn whisker growth.The Mg_(2)Sn accumulation at the grain boundaries would pin the dislocation slip and affect the continuity of whisker growth,and the boundary angle would thus play a decisive role in the growth shape of Sn whiskers due to the pining effect of Mg_(2)Sn.This study might be conducive to elucidating the growth behavior of Sn whiskers and provide the exploration strategy to further improve the bonding strength of Mg/Sn/Mg ultrasonic-assisted soldering joints.
基金supported by the National Natural Science Foundation of China(No.50609009)Natural Science Foundation of College of Jiangsu Province(No.07KJD580056)
文摘Many factors influence the fatigue and crack growth behavior of welded joints. Some structures often undergo fairly large static loading before they enter service or variable amplitude cyclic loading when they are in service. The combined effect of both applied stress and high initial residual stress is expected to cause the residual stresses relaxation. Only a few papers seem to deal with appropriate procedures for fatigue analysis and crack growth by considering the combined effect of variable amplitude cyclic loading with residual stresses relaxation. In this article, some typical welded connections in ship-shaped structures are investigated with 3-D elastic-plastic finite element analysis. The effect of residual stress relaxation, initial residual stress, and the applied load after variable amplitude cyclic loading is revealed, and a formula for predicting the residual stress at hot spot quantitatively is proposed. Based on the formula, an improved fatigue procedure is introduced. Moreover, crack growth of typical weld joints considering residual stresses relaxation is studied.
基金Supported by National Key Technology Support Program(2012BAD19B01)
文摘Joint toxicity of Beauveria bassiana and two insect growth regulators, methoxyfenozide and hexaflumuron, on beet annywonn larvae, Spodoptera exigua （ Htthner）, were investigated. An obvious synergism effect of the two insect growth regulators with B. beauveria was observed. When the insect growth regulators at LC50 concentrations （25 × 10^-6 g/L for methoxyfenozide and 1 000 × 10^ -6 g/L for hexaflumuren） were mixed with B. bassiana at the volume ratio of 4： 1, the mixtures achieved the best efficacy. The co-toxicity co-efficient （CTC） of methexyfenozide and B. bass/ana was 285, and that of hexaflumuron and B. bass/ana was 208. Scanning electron microscope observation of the longitudinal section of S. exigua revealed obviously different patterns of integument in different treatment groups.
文摘Objective: The aim of the study was to evaluate the effect of platelet rich growth factors (PRGFs) in treatment of temporomandibular joint disc displacement. Materials and Methods: The study subjects included 8 females having bilateral anterior disc displacement with reduction and 1 female having bilateral anterior disc displacement without reduction with the age range between 20 - 35 years. The process of obtaining PRGFs was carried out following the Anitua Technique. Results: Clinical parameters of Interincisal distance, Lateral excursion of mandible using digital caliper in millimeters and Visual Analogue Scale (VAS 0/10) for pain intensity score were used. All of these parameters were running through the intervals of two, four, and eight weeks till the end of the follow-up period at twenty-six weeks (six months). The participated patients showed the clinical improvement in the different clinical statuses such as interincisal distance;lateral excursion of mandible and Pain Score. Conclusion: the study reported early efficacy of PRGFs after the arthrocentesis of the joint in treatment of TMJ disc displacement, and according to our results, the injection of PRGFs could be a possible alternative treatment for patients who did not respond to standard treatment.
文摘目的观察火针联合董氏奇穴针刺治疗肩袖损伤的临床疗效及对关节功能及血清前列腺素E_(2)(prostaglandin E_(2),PGE_(2))和转化生长因子-β1(transforming growth factor-β1,TGF-β1)的影响。方法将100例肩袖损伤患者随机分为对照组(50例)和观察组(50例)。对照组予以电针联合董氏奇穴针刺治疗,观察组予以火针联合董氏奇穴针刺治疗。检测视觉模拟量表(visual analog scale,VAS)和美国加利福尼亚大学洛杉矶分校(University of California,Los Angeles,UCLA)肩关节评分、肩关节活动度(range of motion,ROM)及血清PGE_(2)和TGF-β1水平。结果观察组总有效率高于对照组(P<0.05)。治疗后及4周随访时,两组VAS评分及血清PGE_(2)和TGF-β1水平均低于治疗前(P<0.05),且观察组均低于对照组(P<0.05);两组UCLA肩关节评分和肩关节ROM均高于治疗前(P<0.05),且观察组均高于对照组(P<0.05)。4周随访时,两组VAS评分、UCLA肩关节评分、肩关节ROM及血清PGE_(2)和TGF-β1水平与治疗后比较差异无统计系意义(P>0.05)。治疗后血清PGE_(2)、TGF-β1水平与VAS评分呈正相关,与UCLA肩关节评分呈负相关。结论火针和电针联合董氏奇穴针刺治疗肩袖损伤均可缓解疼痛、改善肩关节功能,但火针优于电针,其机制可能与降低血清PGE_(2)和TGF-β1水平有关。
文摘Double edge notched tensile （DENT） tests were carried out to investigate the slow crack growth （SCG） behavior of PESO welded joints. Efforts were made to acquire creep fracture parameters which can characterize creep resistance. Results show that creep compliance indicates an ascending trend with the increase of applied stress. A global creep load parameter is obtained. It has a linear relationship with fkacture time in logarithmic coordinate system and helps to predict the fracture time at any applied load.
