The GH4169 superalloy with different content ofδ-Ni3Nb phase was welded by tungsten inert gas welding.A detailed study of microstructure and hardness of heat-affected zone(HAZ)was performed in both as-welded and aged...The GH4169 superalloy with different content ofδ-Ni3Nb phase was welded by tungsten inert gas welding.A detailed study of microstructure and hardness of heat-affected zone(HAZ)was performed in both as-welded and aged state.The results show that the precipitation ofδphase,especially the intergranularδphase,can lead to the enrichment of Nb and Mo elements,which promote the formation ofγ/Laves eutectic constituent at grain boundaries in HAZ.In as-welded state,the hardness decreases first and then increases(exhibiting a"V"shape)with distance away from fusion line in HAZ,which is governed by grain size.After aging treatment,however,theγ″phase plays a key role in hardness and leads to the"■"shape profiles of hardness in HAZ.展开更多
The natural melanin is one kind of ubiquitous biological pigments, which is produced in melanosomes and widely distributed in living organisms. The synthetic melanin, often known as polydopamine(PDA), has similar chem...The natural melanin is one kind of ubiquitous biological pigments, which is produced in melanosomes and widely distributed in living organisms. The synthetic melanin, often known as polydopamine(PDA), has similar chemical compositions and physical properties to natural melanin. In recent years, both natural melanin and PDA have aroused increased research interests in biomedical fields owing to their inherent biocompatibility, antioxidant activity, free-radical scavenging, metal ion chelation,strong near-infrared absorption and high photothermal conversion efficiency. Inspired by these fascinating properties, melanin and PDA have been widely used as building blocks for the construction of multifunctional nanoplatforms for various biomedical applications. This review focuses on the state-of-the-art progress in melanin/PDA-based nanomaterials, which covers from their preparation methods to biomedical applications including bioimaging, treatment, theranostics, antibacterial, UV/radiation protection, biosensor and tissue engineering. Moreover, the current trends and the future prospects of melanin/PDA-based nanomaterials are also discussed.展开更多
Golay codes are the most practical code in coded ultrasound imaging systems.But the trade-off for perfect range sidelobe cancellation is the requirement for two firings, thus resulting in motion-dependent decoding err...Golay codes are the most practical code in coded ultrasound imaging systems.But the trade-off for perfect range sidelobe cancellation is the requirement for two firings, thus resulting in motion-dependent decoding errors.In view of this, we propose a new scheme using the simultaneous emission of code pairs.The code pair is allocated to different elements of an aperture and transmitted simultaneously.The process of separating the code pair from the echo received is based on the orthogonality of the code pair.At last the autocorrelation functions of the individual Golay codes are added together.The simultaneous emission of code pairs instead of two firings recovers the frame rate loss, and eliminates the motion-dependent decoding error.Our theoretical analysis and simulations show that the scheme can be used to eliminate the tissue motion effects.展开更多
基金financially supported by the National Natural Science Foundation of China (No.51774213)the Regional Demonstration Project of Marine Economic Innovation and Development (No.BHSF2017-10)
文摘The GH4169 superalloy with different content ofδ-Ni3Nb phase was welded by tungsten inert gas welding.A detailed study of microstructure and hardness of heat-affected zone(HAZ)was performed in both as-welded and aged state.The results show that the precipitation ofδphase,especially the intergranularδphase,can lead to the enrichment of Nb and Mo elements,which promote the formation ofγ/Laves eutectic constituent at grain boundaries in HAZ.In as-welded state,the hardness decreases first and then increases(exhibiting a"V"shape)with distance away from fusion line in HAZ,which is governed by grain size.After aging treatment,however,theγ″phase plays a key role in hardness and leads to the"■"shape profiles of hardness in HAZ.
基金supported by the National Natural Science Foundation of China (51802202, 51703132, 51573096, 21807074)the Postdoctoral Science Foundation of China (2017M612727, 2018M633123)+2 种基金the National Postdoctoral Program for Innovative Talents (BX201600111)the Guangdong Province Natural Science Foundation of PhD Start-up Fund (2018A030310566, 2018A030310574)the Basic Research Program of Shenzhen (JCYJ20170412111100742, JCYJ20160422091238319)
文摘The natural melanin is one kind of ubiquitous biological pigments, which is produced in melanosomes and widely distributed in living organisms. The synthetic melanin, often known as polydopamine(PDA), has similar chemical compositions and physical properties to natural melanin. In recent years, both natural melanin and PDA have aroused increased research interests in biomedical fields owing to their inherent biocompatibility, antioxidant activity, free-radical scavenging, metal ion chelation,strong near-infrared absorption and high photothermal conversion efficiency. Inspired by these fascinating properties, melanin and PDA have been widely used as building blocks for the construction of multifunctional nanoplatforms for various biomedical applications. This review focuses on the state-of-the-art progress in melanin/PDA-based nanomaterials, which covers from their preparation methods to biomedical applications including bioimaging, treatment, theranostics, antibacterial, UV/radiation protection, biosensor and tissue engineering. Moreover, the current trends and the future prospects of melanin/PDA-based nanomaterials are also discussed.
基金supported by the National Natural Science Foundation of China(Nos.61031003,81271651,and 61101025)the Shenzhen Basic Research Project(No.JC201005280501A),China
基金Project supported by the National Natural Science Foundation of China (Nos. 60772147 and 60871060)the Science and Technology Planning Project of Shenzhen City, China (No. JC200903120129A)
文摘Golay codes are the most practical code in coded ultrasound imaging systems.But the trade-off for perfect range sidelobe cancellation is the requirement for two firings, thus resulting in motion-dependent decoding errors.In view of this, we propose a new scheme using the simultaneous emission of code pairs.The code pair is allocated to different elements of an aperture and transmitted simultaneously.The process of separating the code pair from the echo received is based on the orthogonality of the code pair.At last the autocorrelation functions of the individual Golay codes are added together.The simultaneous emission of code pairs instead of two firings recovers the frame rate loss, and eliminates the motion-dependent decoding error.Our theoretical analysis and simulations show that the scheme can be used to eliminate the tissue motion effects.
