The East Asian Very Long Baseline Interferometry(VLBI) Network(EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China,Japan and Korea.EAVN aims at forming a joi...The East Asian Very Long Baseline Interferometry(VLBI) Network(EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China,Japan and Korea.EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions.After the combination of the Korean VLBI Network(KVN) and the VLBI Exploration of Radio Astrometry(VERA) into Ka VA,further expansion with the joint array in East Asia is actively promoted.Here we report the first imaging results(at 22 and 43 GHz) of bright radio sources obtained with Ka VA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China.To test the EAVN imaging performance for different sources,we observed four active galactic nuclei(AGN) having different brightness and morphology.As a result,we confirmed that the Tianma 65-m Radio Telescope(TMRT) significantly enhances the overall array sensitivity,a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of Ka VA only.The addition of the Nanshan 26-m Radio Telescope(NSRT) further doubled the east-west angular resolution.With the resulting high-dynamic-range,high-resolution images with EAVN(Ka VA+TMRT+NSRT),various fine-scale structures in our targets,such as the counter-jet in M87,a kink-like morphology of the 3 C 273 jet and the weak emission in other sources are successfully detected.This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general.Ongoing expansion of EAVN will further enhance the angular resolution,detection sensitivity and frequency coverage of the network.展开更多
A microneedle(MN)array is a novel biomedical device adopted in medical applications to pierce through the stratum corneum while targeting the viable epidermis and dermis layers of the skin.Owing to their micron-scale ...A microneedle(MN)array is a novel biomedical device adopted in medical applications to pierce through the stratum corneum while targeting the viable epidermis and dermis layers of the skin.Owing to their micron-scale dimensions,MNs can minimize stimulations of the sensory nerve fibers in the dermis layer.For medical applications,such as wound healing,biosensing,and drug delivery,the structure of MNs significantly influences their mechanical properties.Among the various microfabrication methods for MNs,fused deposition modeling(FDM),a commercial 3D printing method,shows potential in terms of the biocompatibility of the printed material(polylactic acid(PLA))and preprogrammable arbitrary shapes.Owing to the current limitations of FDM printer resolution,conventional micron-scale MN structures cannot be fabricated without a post-fabrication process.Hydrolysis in an alkaline solution is a feasible approach for reducing the size of PLA needles printed via FDM.Moreover,weak bonding between PLA layers during additive manufacturing triggers the detachment of PLA needles before etching to the expected sizes.Furthermore,various parameters for the fabrication of PLA MNs with FDM have yet to be sufficiently optimized.In this study,the thermal parameters of the FDM printing process,including the nozzle and printing stage temperatures,were investigated to bolster the interfacial bonding between PLA layers.Reinforced bonding was demonstrated to address the detachment challenges faced by PLA MNs during the chemical etching process.Furthermore,chemical etching parameters,including the etchant concentration,environmental temperature,and stirring speed of the etchant,were studied to determine the optimal etching ratio.To develop a universal methodology for the batch fabrication of biodegradable MNs,this study is expected to optimize the conditions of the FDM-based fabrication process.Additive manufacturing was employed to produce MNs with preprogrammed structures.Inclined MNs were successfully fabricated by FDM printing with chemical etching.This geometrical structure can be adopted to enhance adhesion to the skin layer.Our study provides a useful method for fabricating MN structures for various biomedical applications.展开更多
基金supported by The Graduate University for Advanced Studies (SOKENDAI)supported by the Japanese Government (MEXT) Scholarship+18 种基金supported by JSPS KAKENHI Grant Numbers JP18K03656 (M.K.),JP18H03721 (K.N.,K.H.and M.K.),JP19H01943 (K.H.,F.T.and Y.H.) and JP18KK0090 (K.H.and F.T.)supported by the Mitsubishi Foundation (grant number 201911019)supported by an EACOA Fellowship awarded by the East Asia Core Observatories Association,which consists of the Academia Sinica Institute of Astronomy and Astrophysics,the National Astronomical Observatory of Japan,the Center for Astronomical Mega-Science,the Chinese Academy of Sciencesthe Korea Astronomy and Space Science Institutethe financial support from the National Research Foundation (NRF) of Korea via Global Ph.D.Fellowship Grant 2014H1A2A1018695 and 2015H1A2A1033752,respectivelysupport from the NRF via Grant 2019R1F1A1059721supported by the Major Program of the National Natural Science Foundation of China (NSFC,Grant Nos.11590780 and 11590784)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KJCX1-YW-18)the Scientific Program of Shanghai Municipality (08DZ1160100)Key Laboratory for Radio Astronomy,CASsupport from NSFC (Grant No.11803071)supported by the National Key R&D Program of China (Grant No.2018YFA0404602)the CAS ‘Light of West China’ Program (Grant No.2018-XBQNXZ-B021)the NSFC (Grant Nos.U2031212 and 61931002)the Youth Innovation Promotion Association of the CAS (Grant No.2017084)support from Fundamental Research Grant Scheme (FRGS) FRGS/1/2019/STG02/UM/02/6supported by the Max Planck Partner Group of the MPG and the CASthe support by the Key Program of the NSFC (Grant No.11933007)the Research Program of Fundamental and Frontier Sciences,CAS (Grant No.ZDBS-LY-SLH011)。
文摘The East Asian Very Long Baseline Interferometry(VLBI) Network(EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China,Japan and Korea.EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions.After the combination of the Korean VLBI Network(KVN) and the VLBI Exploration of Radio Astrometry(VERA) into Ka VA,further expansion with the joint array in East Asia is actively promoted.Here we report the first imaging results(at 22 and 43 GHz) of bright radio sources obtained with Ka VA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China.To test the EAVN imaging performance for different sources,we observed four active galactic nuclei(AGN) having different brightness and morphology.As a result,we confirmed that the Tianma 65-m Radio Telescope(TMRT) significantly enhances the overall array sensitivity,a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of Ka VA only.The addition of the Nanshan 26-m Radio Telescope(NSRT) further doubled the east-west angular resolution.With the resulting high-dynamic-range,high-resolution images with EAVN(Ka VA+TMRT+NSRT),various fine-scale structures in our targets,such as the counter-jet in M87,a kink-like morphology of the 3 C 273 jet and the weak emission in other sources are successfully detected.This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general.Ongoing expansion of EAVN will further enhance the angular resolution,detection sensitivity and frequency coverage of the network.
文摘A microneedle(MN)array is a novel biomedical device adopted in medical applications to pierce through the stratum corneum while targeting the viable epidermis and dermis layers of the skin.Owing to their micron-scale dimensions,MNs can minimize stimulations of the sensory nerve fibers in the dermis layer.For medical applications,such as wound healing,biosensing,and drug delivery,the structure of MNs significantly influences their mechanical properties.Among the various microfabrication methods for MNs,fused deposition modeling(FDM),a commercial 3D printing method,shows potential in terms of the biocompatibility of the printed material(polylactic acid(PLA))and preprogrammable arbitrary shapes.Owing to the current limitations of FDM printer resolution,conventional micron-scale MN structures cannot be fabricated without a post-fabrication process.Hydrolysis in an alkaline solution is a feasible approach for reducing the size of PLA needles printed via FDM.Moreover,weak bonding between PLA layers during additive manufacturing triggers the detachment of PLA needles before etching to the expected sizes.Furthermore,various parameters for the fabrication of PLA MNs with FDM have yet to be sufficiently optimized.In this study,the thermal parameters of the FDM printing process,including the nozzle and printing stage temperatures,were investigated to bolster the interfacial bonding between PLA layers.Reinforced bonding was demonstrated to address the detachment challenges faced by PLA MNs during the chemical etching process.Furthermore,chemical etching parameters,including the etchant concentration,environmental temperature,and stirring speed of the etchant,were studied to determine the optimal etching ratio.To develop a universal methodology for the batch fabrication of biodegradable MNs,this study is expected to optimize the conditions of the FDM-based fabrication process.Additive manufacturing was employed to produce MNs with preprogrammed structures.Inclined MNs were successfully fabricated by FDM printing with chemical etching.This geometrical structure can be adopted to enhance adhesion to the skin layer.Our study provides a useful method for fabricating MN structures for various biomedical applications.