Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts.To accurately predict necking defects,new judgement conditions are established based on the thermal p...Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts.To accurately predict necking defects,new judgement conditions are established based on the thermal performance of 6082 aluminium alloy.The limit-sectional shrinkage without necking defects is achieved by combining theoretical calculation and finite-element model analysis,which couples heat transfer and deformation.In this paper,a 6082 aluminium alloy extruded rod with a 40 mm diameter rolled at a preheated temperature of 500℃and a rolling angular velocity of 1 rad/s is taken as an example.The simulation and experimental results show that necking defects do not occur on the rolled pieces if the sectional shrinkage is below the limit-sectional shrinkage but will occur when the sectional shrinkage is above it.The results prove that the prediction model of necking defects in cross-wedge rolling of 6082 aluminum alloy is feasible,and this research provides a theoretical basis for the qualified aluminum alloy shafts produced by the cross-wedge rolling.展开更多
Bird migration is a seasonal movement between breeding and wintering grounds.Opinions are widely divided on the reasons for this movement.According to biological data including:geographic distribution,reproductive phy...Bird migration is a seasonal movement between breeding and wintering grounds.Opinions are widely divided on the reasons for this movement.According to biological data including:geographic distribution,reproductive physiology,comparison of breeding and wintering habitats,geological data including Qinghai Tibetan Plateau uplift and Quatemary Period glaciation,it is inferred that bird migration is a survival mechanism,and that migration originated on the breeding grounds.展开更多
Aim Head and neck cancers are the eighth most common cancer worldwide. Despite significant ad- vances in the delivery of treatment and surgical reconstruction, the mortality rates for this disease have not improved in...Aim Head and neck cancers are the eighth most common cancer worldwide. Despite significant ad- vances in the delivery of treatment and surgical reconstruction, the mortality rates for this disease have not improved in the past 4 decades. Our previous study has shown that HIV protease inhibitors （HIV PIs） induce cell apoptosis via activating endoplasmic reticulum （ER） stress. It also has been reported that a few HIV PIs are able to radio- sensitize tumor cells. However, the underlying cellular mechanisms remain to be identified. The aim of this study was to examine whether HIV PIs activate the ER stress response and sensitize human head and neck carcinoma cells to radiation. Methods Human SQ20B and Fadu cells and the most commonly used HIV PIs, lopinavir and ritona- vir, were used in this study. The mRNA and protein levels of ER stress-related genes （ CHOP, ATF4, XBP-1, and GRP78 ） were detected by real time RT-PCR and Western blot, respectively. Cell viability and apoptosis were ana- lyzed using Cellometer Vision CBA. After treatment with HIV PIs, cells were irradiated at a dose of 2G or 4G. Col- onies were stained and counted 10 days after irradiation. Results HIV PIs significantly induced activation of ER stress and apoptosis. Treatment of HIV PIs inhibited Akt phosphorylation, induced cell cycle arrest in G1 phase and increased tumor cell sensitivity to irradiation-induced cell death. Conclusion HIV PIs sensitize human head and neck carcinoma cells to radiation by activating ER stress.展开更多
Based on the concepts of species and speciation,the speciation of Black necked Grane(Grus nigricollis) was discussed using bio geographic principles and some evidences suggest that Black necked Grane had a close re...Based on the concepts of species and speciation,the speciation of Black necked Grane(Grus nigricollis) was discussed using bio geographic principles and some evidences suggest that Black necked Grane had a close relationship with Red crowned Crane(Grus japonensis).The Qinghai Tibetan Plateau uplift may be the most important factor in allopatric speciation for Black necked Crane.展开更多
Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The functio...Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.展开更多
Introduction-The cervical spine is subjected to injury frequently,especially among pilots who are usually on the condition of high acceleration.Injuries of the cervical spine will be potential risk of damage to the sp...Introduction-The cervical spine is subjected to injury frequently,especially among pilots who are usually on the condition of high acceleration.Injuries of the cervical spine will be potential risk of damage to the spinal cord,which could be result in life threatening展开更多
基金Project(51975301)supported by the National Natural Science Foundation of ChinaProject(LZ17E050001)supported by the National Natural Science Foundation of Zhejiang Province of China。
文摘Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts.To accurately predict necking defects,new judgement conditions are established based on the thermal performance of 6082 aluminium alloy.The limit-sectional shrinkage without necking defects is achieved by combining theoretical calculation and finite-element model analysis,which couples heat transfer and deformation.In this paper,a 6082 aluminium alloy extruded rod with a 40 mm diameter rolled at a preheated temperature of 500℃and a rolling angular velocity of 1 rad/s is taken as an example.The simulation and experimental results show that necking defects do not occur on the rolled pieces if the sectional shrinkage is below the limit-sectional shrinkage but will occur when the sectional shrinkage is above it.The results prove that the prediction model of necking defects in cross-wedge rolling of 6082 aluminum alloy is feasible,and this research provides a theoretical basis for the qualified aluminum alloy shafts produced by the cross-wedge rolling.
文摘Bird migration is a seasonal movement between breeding and wintering grounds.Opinions are widely divided on the reasons for this movement.According to biological data including:geographic distribution,reproductive physiology,comparison of breeding and wintering habitats,geological data including Qinghai Tibetan Plateau uplift and Quatemary Period glaciation,it is inferred that bird migration is a survival mechanism,and that migration originated on the breeding grounds.
文摘Aim Head and neck cancers are the eighth most common cancer worldwide. Despite significant ad- vances in the delivery of treatment and surgical reconstruction, the mortality rates for this disease have not improved in the past 4 decades. Our previous study has shown that HIV protease inhibitors （HIV PIs） induce cell apoptosis via activating endoplasmic reticulum （ER） stress. It also has been reported that a few HIV PIs are able to radio- sensitize tumor cells. However, the underlying cellular mechanisms remain to be identified. The aim of this study was to examine whether HIV PIs activate the ER stress response and sensitize human head and neck carcinoma cells to radiation. Methods Human SQ20B and Fadu cells and the most commonly used HIV PIs, lopinavir and ritona- vir, were used in this study. The mRNA and protein levels of ER stress-related genes （ CHOP, ATF4, XBP-1, and GRP78 ） were detected by real time RT-PCR and Western blot, respectively. Cell viability and apoptosis were ana- lyzed using Cellometer Vision CBA. After treatment with HIV PIs, cells were irradiated at a dose of 2G or 4G. Col- onies were stained and counted 10 days after irradiation. Results HIV PIs significantly induced activation of ER stress and apoptosis. Treatment of HIV PIs inhibited Akt phosphorylation, induced cell cycle arrest in G1 phase and increased tumor cell sensitivity to irradiation-induced cell death. Conclusion HIV PIs sensitize human head and neck carcinoma cells to radiation by activating ER stress.
文摘Based on the concepts of species and speciation,the speciation of Black necked Grane(Grus nigricollis) was discussed using bio geographic principles and some evidences suggest that Black necked Grane had a close relationship with Red crowned Crane(Grus japonensis).The Qinghai Tibetan Plateau uplift may be the most important factor in allopatric speciation for Black necked Crane.
文摘Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.
文摘Introduction-The cervical spine is subjected to injury frequently,especially among pilots who are usually on the condition of high acceleration.Injuries of the cervical spine will be potential risk of damage to the spinal cord,which could be result in life threatening
