The effect of the surface wettability of plasma-modified vertical Si nanowire array on the bio-fouling performance has been investigated.The Si nanowires prepared by a metal-assisted chemical etching technique exhibit...The effect of the surface wettability of plasma-modified vertical Si nanowire array on the bio-fouling performance has been investigated.The Si nanowires prepared by a metal-assisted chemical etching technique exhibit a super-hydrophilic surface.The treatment in CH4/H2 gas plasma environment leads to the decoration of graphite and diamond nanoparticles around Si nanowires.The detailed interface between graphite/diamond and Si nanowire was characterized by HRTEM technique.These surface-modified nanowire samples show an increased water contact angle with ultrananocrystalline diamond decorated ones being superhydrophobic.The immersion test in chlorella solution reveals that the diamond-coated Si nanowires possess the least attachment of chlorella in comparison with other Si nanowires.This result confirms that the coating of Si nanowires with diamond nanoparticles shows the best behavior in anti-biofouling.Importantly,this work provides a method fabricated super-hydrophobic surface for the application of biofouling prevention.展开更多
The Stellar Abundances and Galactic Evolution Survey(SAGES)is a multi-band survey that covers the northern sky area of~12,000 deg2.The Nanshan One-meter Wide-field Telescope(NOWT)of the Xinjiang Astronomical Observato...The Stellar Abundances and Galactic Evolution Survey(SAGES)is a multi-band survey that covers the northern sky area of~12,000 deg2.The Nanshan One-meter Wide-field Telescope(NOWT)of the Xinjiang Astronomical Observatory carried out observations on g/r/i bands.Here,we present the survey strategy,data processing,catalog construction,and database schema.The observations of NOWT started in 2016 August and were completed in2018 January,a total of 17,827 frames were obtained and~4600 deg2 sky areas were covered.In this paper,we release the catalog of the data in the g/r/i bands observed by NOWT.In total,there are 109,197,578 items of source records.The catalog is the supplement for the SDSS for the bright end,and the combination of our catalog and these catalogs could be helpful for source selections for other surveys and Milky Way sciences,e.g.,white dwarf candidates and stellar flares.展开更多
Chemical composition of very metal-poor(VMP)stars can provide observational constraints on current models of nucleosynthesis and the chemical evolution of the Galaxy.It has been found that the scatter of[Na/Fe]versus[...Chemical composition of very metal-poor(VMP)stars can provide observational constraints on current models of nucleosynthesis and the chemical evolution of the Galaxy.It has been found that the scatter of[Na/Fe]versus[Fe/H]in VMP stars is very large in contrast with most other elements.Moreover,a negative slope in[Na/Fe]versus[Fe/H]was found for giants,which is very unlikely according to the theory of nucleosynthesis.For the sample of93 VMP stars in the metallicity range-4.25<[Fe/H]<-1.64 we obtained NLTE sodium abundances using the line profile fitting method by employing accurate atmospheric parameters determined when taking into account NLTE line formation for both FeⅠand FeⅡ.Originally selected from the LAMOST low-resolution spectral database,the spectra of stars were obtained with the High Dispersion Spectrograph of the Subaru Telescope.For 57turn-off stars in metallicity domain-3.04<[Fe/H]<-1.64,we obtained mean[Na/Fe]=-0.29±0.14 and positive slope 0.09±0.06.For 21 giants distributed over metallicity-3.59<[Fe/H]<-2.19,we found mean[Na/Fe]=-0.35±0.1 and positive slope 0.07±0.07.Our[Na/Fe]trend is lower by~0.2 dex,compared to the modern GCE model.We believe the GCE model should be adjusted,by considering the associated scatter.Twelve stars in our sample are found to be outliers,with too low or too high Na abundances.展开更多
The accuracy of the estimated stellar atmospheric parameter evidently decreases with the decreasing of spectral signal-to-noise ratio(S/N)and there are a huge amount of this kind observations,especially in case of S/N...The accuracy of the estimated stellar atmospheric parameter evidently decreases with the decreasing of spectral signal-to-noise ratio(S/N)and there are a huge amount of this kind observations,especially in case of S/N<30.Therefore,it is helpful to improve the parameter estimation performance for these spectra and this work studied the(T_(eff),log g,[Fe/H])estimation problem for LAMOST DR8 low-resolution spectra with 20≤S/N<30.We proposed a data-driven method based on machine learning techniques.First,this scheme detected stellar atmospheric parameter-sensitive features from spectra by the Least Absolute Shrinkage and Selection Operator(LASSO),rejected ineffective data components and irrelevant data.Second,a Multi-layer Perceptron(MLP)method was used to estimate stellar atmospheric parameters from the LASSO features.Finally,the performance of the LASSO-MLP was evaluated by computing and analyzing the consistency between its estimation and the reference from the Apache Point Observatory Galactic Evolution Experiment high-resolution spectra.Experiments show that the Mean Absolute Errors of T_(eff),log g,[Fe/H]are reduced from the LASP(137.6 K,0.195,0.091 dex)to LASSO-MLP(84.32 K,0.137,0.063 dex),which indicate evident improvements on stellar atmospheric parameter estimation.In addition,this work estimated the stellar atmospheric parameters for 1,162,760 lowresolution spectra with 20≤S/N<30 from LAMOST DR8 using LASSO-MLP,and released the estimation catalog,learned model,experimental code,trained model,training data and test data for scientific exploration and algorithm study.展开更多
Lithium is an ancient element that was first produced by the Big Bang Nucleosynthesis(BBN)a few minutes after the birth of the Universe.Lithium is a sensitive tracer for a number of processes in a variety of astrophys...Lithium is an ancient element that was first produced by the Big Bang Nucleosynthesis(BBN)a few minutes after the birth of the Universe.Lithium is a sensitive tracer for a number of processes in a variety of astrophysical environments due to its multi-channels of production and fragility.These features also make lithium a complex element at the center of many unsolved problems.The behavior of lithium in the low-mass evolved stars is one such issue.It is known that such stars not only destroy but also produce lithium,while neither the destruction details nor the production mechanisms over different evolutionary phases are clear.In this paper,we summarize the recent results obtained from the studies combining large-scale spectroscopic surveys,asteroseismology,and traditional high-resolution spectroscopy.We present the detailed evolution behaviors from the red giant branch(RGB)to the red clump(RC)phase characterized by the core helium-burning in the stellar interior.We show the new signatures discovered from the recent studies for the lithium-enhanced giants and also discuss various observational and theoretical constraints on lithium production in red clump stars.展开更多
The Chinese Space Station Survey Telescope(CSST)is an upcoming Stage-IV sky survey telescope,distinguished by its large field of view(Fo V),high image quality,and multi-band observation capabilities.It can simultaneou...The Chinese Space Station Survey Telescope(CSST)is an upcoming Stage-IV sky survey telescope,distinguished by its large field of view(Fo V),high image quality,and multi-band observation capabilities.It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys.The CSST is equipped with five scientific instruments,i.e.,Multi-band Imaging and Slitless Spectroscopy Survey Camera(SC),Multi-Channel Imager(MCI),Integral Field Spectrograph(IFS),Cool Planet Imaging Coronagraph(CPI-C),and THz Spectrometer(TS).Using these instruments,CSST is expected to make significant contributions and discoveries across various astronomical fields,including cosmology,galaxies and active galactic nuclei(AGN),the Milky Way and nearby galaxies,stars,exoplanets,Solar System objects,astrometry,and transients and variable sources.This review aims to provide a comprehensive overview of the CSST instruments,observational capabilities,data products,and scientific potential.展开更多
In situ pressure-induced Raman spectral changes of 1-octyl-3-methyl imidazolium hexafluorophosphate([OMIM][PF6])have been investigated under the pressure up to 5.86 GPa at room temperature.The results indicated that[O...In situ pressure-induced Raman spectral changes of 1-octyl-3-methyl imidazolium hexafluorophosphate([OMIM][PF6])have been investigated under the pressure up to 5.86 GPa at room temperature.The results indicated that[OMIM][PF6]experienced a phase transition at about4.12 GPa during compression,and it was thought as a phase transition of liquid to a superpressurized glass.Upon decompression,from the obvious change of Raman spectra of[OMIM][PF6]at about 0.48 GPa,it could be inferred that a decompression-induced disorder to order phase transition in[OMIM][PF6]occurred.The phase behavior of[OMIM][PF6]at low temperature under atmospheric pressure was also investigated in detail.The result showed that Raman spectra of[OMIM][PF6]varied slightly and no crystallization occurred upon cooling.These facts suggested that a disorder to order phase transition was induced by decompression in[OMIM][PF6],and[OMIM][PF6]served as a superpressurized glass under the pressure above4.12 GPa,which was similar to the glassy state at low temperature.展开更多
Photothermal agents(PTAs)with ultra-high photothermal conversion efficiency(PCE)activated upon near-infrared(NIR)laser irradiation can heat up and destroy tumor cells under low-intensity laser excitation to allow safe...Photothermal agents(PTAs)with ultra-high photothermal conversion efficiency(PCE)activated upon near-infrared(NIR)laser irradiation can heat up and destroy tumor cells under low-intensity laser excitation to allow safe and efficient tumor therapy.Herein,an organic PTA with an outstanding PCE of 89.6%is developed from rationally designed perylene diimide(PDI)with electron-donating cyclohexylamine moiety at the bay-positions of its skeleton and chiral phenethylamine(PEA)moiety at its N terminals,termed here PEAPDI.The strong intermolecular interaction between the PDI skeletons induced by PEA together with the intramolecular charge transfer from cyclohexylamine to PDI skeleton severely quenches the fluorescence emission from PEAPDI and significantly enhances its NIR absorption,resulting in super NIR–photothermal conversion.PEAPDI molecules are subsequently encapsulated within silica nanocapsules(SNCs),creating PEAPDI@SNC.Characterized by its small hydrodynamic diameter,monodispersity,high PDI encapsulation efficiency,colloidal stability,and biocompatibility,PEAPDI@SNC exhibits prolonged blood circulation and enhanced permeability and retention effect,enabling targeted accumulation at the tumor site.An in vivo study using a 4T1 tumor–bearing mice model illustrates the agent’s potent tumor ablation capability without side effects at low dosage under NIR laser irradiation(808 nm).The findings demonstrate PEAPDI@SNC’s significant potential as a PTA for tumor treatment.展开更多
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),also known as the Guoshoujing Telescope,is a major national scientific facility for astronomical research located in Xinglong,China.Beginning with ...The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),also known as the Guoshoujing Telescope,is a major national scientific facility for astronomical research located in Xinglong,China.Beginning with a pilot survey in 2011,LAMOST has been surveying the night sky for more than 10 years.The LAMOST survey covers various objects in the Universe,from normal stars to peculiar ones.展开更多
We humans are always asking why.It seems to be our nature.How did we get here?Are we alone in the universe?How does the universe work?These are the questions we are still trying to answer,which also has been the ultim...We humans are always asking why.It seems to be our nature.How did we get here?Are we alone in the universe?How does the universe work?These are the questions we are still trying to answer,which also has been the ultimate goal of astronomy for thousands of years.For centuries,telescopes,being powerful tools for exploring the universe,have enabled us to probe beyond what we can reach on our own.Just this summer,an already-legendary telescope,the 6.5-m James Webb Space Telescope(JWST),has started to take astronomers a step closer to their ultimate goal.展开更多
基金supported by the National Natural Science Foundation of China(No.51872294)。
文摘The effect of the surface wettability of plasma-modified vertical Si nanowire array on the bio-fouling performance has been investigated.The Si nanowires prepared by a metal-assisted chemical etching technique exhibit a super-hydrophilic surface.The treatment in CH4/H2 gas plasma environment leads to the decoration of graphite and diamond nanoparticles around Si nanowires.The detailed interface between graphite/diamond and Si nanowire was characterized by HRTEM technique.These surface-modified nanowire samples show an increased water contact angle with ultrananocrystalline diamond decorated ones being superhydrophobic.The immersion test in chlorella solution reveals that the diamond-coated Si nanowires possess the least attachment of chlorella in comparison with other Si nanowires.This result confirms that the coating of Si nanowires with diamond nanoparticles shows the best behavior in anti-biofouling.Importantly,this work provides a method fabricated super-hydrophobic surface for the application of biofouling prevention.
基金supported by the National Natural Science Foundation of China(NSFC)under grant Nos.12261141689,12090044,and 12090040sponsored by the Xinjiang Uygur Autonomous Region“Tianchi Talent”Introduction Plan。
文摘The Stellar Abundances and Galactic Evolution Survey(SAGES)is a multi-band survey that covers the northern sky area of~12,000 deg2.The Nanshan One-meter Wide-field Telescope(NOWT)of the Xinjiang Astronomical Observatory carried out observations on g/r/i bands.Here,we present the survey strategy,data processing,catalog construction,and database schema.The observations of NOWT started in 2016 August and were completed in2018 January,a total of 17,827 frames were obtained and~4600 deg2 sky areas were covered.In this paper,we release the catalog of the data in the g/r/i bands observed by NOWT.In total,there are 109,197,578 items of source records.The catalog is the supplement for the SDSS for the bright end,and the combination of our catalog and these catalogs could be helpful for source selections for other surveys and Milky Way sciences,e.g.,white dwarf candidates and stellar flares.
基金funded by the National Natural Science Foundation of China(NSFC,Grant Nos.11988101 and 11890694)the National Key R&D Program of China No.2019YFA0405502。
文摘Chemical composition of very metal-poor(VMP)stars can provide observational constraints on current models of nucleosynthesis and the chemical evolution of the Galaxy.It has been found that the scatter of[Na/Fe]versus[Fe/H]in VMP stars is very large in contrast with most other elements.Moreover,a negative slope in[Na/Fe]versus[Fe/H]was found for giants,which is very unlikely according to the theory of nucleosynthesis.For the sample of93 VMP stars in the metallicity range-4.25<[Fe/H]<-1.64 we obtained NLTE sodium abundances using the line profile fitting method by employing accurate atmospheric parameters determined when taking into account NLTE line formation for both FeⅠand FeⅡ.Originally selected from the LAMOST low-resolution spectral database,the spectra of stars were obtained with the High Dispersion Spectrograph of the Subaru Telescope.For 57turn-off stars in metallicity domain-3.04<[Fe/H]<-1.64,we obtained mean[Na/Fe]=-0.29±0.14 and positive slope 0.09±0.06.For 21 giants distributed over metallicity-3.59<[Fe/H]<-2.19,we found mean[Na/Fe]=-0.35±0.1 and positive slope 0.07±0.07.Our[Na/Fe]trend is lower by~0.2 dex,compared to the modern GCE model.We believe the GCE model should be adjusted,by considering the associated scatter.Twelve stars in our sample are found to be outliers,with too low or too high Na abundances.
基金supported by the National Natural Science Foundation of China(grant Nos.11973022,11973049,and U1811464)the Natural Science Foundation of Guangdong Province(No.2020A1515010710)the Youth Innovation Promotion Association of the CAS(id.Y202017)。
文摘The accuracy of the estimated stellar atmospheric parameter evidently decreases with the decreasing of spectral signal-to-noise ratio(S/N)and there are a huge amount of this kind observations,especially in case of S/N<30.Therefore,it is helpful to improve the parameter estimation performance for these spectra and this work studied the(T_(eff),log g,[Fe/H])estimation problem for LAMOST DR8 low-resolution spectra with 20≤S/N<30.We proposed a data-driven method based on machine learning techniques.First,this scheme detected stellar atmospheric parameter-sensitive features from spectra by the Least Absolute Shrinkage and Selection Operator(LASSO),rejected ineffective data components and irrelevant data.Second,a Multi-layer Perceptron(MLP)method was used to estimate stellar atmospheric parameters from the LASSO features.Finally,the performance of the LASSO-MLP was evaluated by computing and analyzing the consistency between its estimation and the reference from the Apache Point Observatory Galactic Evolution Experiment high-resolution spectra.Experiments show that the Mean Absolute Errors of T_(eff),log g,[Fe/H]are reduced from the LASP(137.6 K,0.195,0.091 dex)to LASSO-MLP(84.32 K,0.137,0.063 dex),which indicate evident improvements on stellar atmospheric parameter estimation.In addition,this work estimated the stellar atmospheric parameters for 1,162,760 lowresolution spectra with 20≤S/N<30 from LAMOST DR8 using LASSO-MLP,and released the estimation catalog,learned model,experimental code,trained model,training data and test data for scientific exploration and algorithm study.
基金This work is supported by the National Natural Science Foundation of China(11988101,12090040,12090044,12022304,11833006,11973052,11973049,11890694,and U2031203)the National Key R&D Program of China(2019YFA0405502)+6 种基金support of the JSPS-CAS Joint Research Program.H.-L.Y.and H.L.acknowledge support from the Youth Innovation Promotion Association of the CAS(id.2019060 and Y202017,respectively)NAOC Nebula Talents Program.J.-H.Z.acknowledges support from NSFC(12103063)from China Postdoctoral Science Foundation funded project(2020M680672)Y.B.K acknowledges the support of the NSFC(11850410437)H.L.acknowledges support from the Strategic Priority Research Program of Chinese Academy of Sciences,(XDB34020205)Guoshoujing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope,LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciences.Funding for the project has been provided by the National Development and Reform CommissionLAMOST is operated and managed by the National Astronomical Observatories,Chinese Academy of Sciences.
文摘Lithium is an ancient element that was first produced by the Big Bang Nucleosynthesis(BBN)a few minutes after the birth of the Universe.Lithium is a sensitive tracer for a number of processes in a variety of astrophysical environments due to its multi-channels of production and fragility.These features also make lithium a complex element at the center of many unsolved problems.The behavior of lithium in the low-mass evolved stars is one such issue.It is known that such stars not only destroy but also produce lithium,while neither the destruction details nor the production mechanisms over different evolutionary phases are clear.In this paper,we summarize the recent results obtained from the studies combining large-scale spectroscopic surveys,asteroseismology,and traditional high-resolution spectroscopy.We present the detailed evolution behaviors from the red giant branch(RGB)to the red clump(RC)phase characterized by the core helium-burning in the stellar interior.We show the new signatures discovered from the recent studies for the lithium-enhanced giants and also discuss various observational and theoretical constraints on lithium production in red clump stars.
基金support of the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-092)the National Key R&D Program of China(Grant Nos.2022YFF0503404,and 2020SKA0110402)+1 种基金the National Natural Science Foundation of China(Grant No.12473002)supported by science research grants from the China Manned Space Project(Grant Nos.CMS-CSST-2025-A02,CMS-CSST-2021-B01,CMSCSST-2021-A01,CMS-CSST-2021-A03,CMS-CSST-2021-A12,and CMSCSST-2021-B10)。
文摘The Chinese Space Station Survey Telescope(CSST)is an upcoming Stage-IV sky survey telescope,distinguished by its large field of view(Fo V),high image quality,and multi-band observation capabilities.It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys.The CSST is equipped with five scientific instruments,i.e.,Multi-band Imaging and Slitless Spectroscopy Survey Camera(SC),Multi-Channel Imager(MCI),Integral Field Spectrograph(IFS),Cool Planet Imaging Coronagraph(CPI-C),and THz Spectrometer(TS).Using these instruments,CSST is expected to make significant contributions and discoveries across various astronomical fields,including cosmology,galaxies and active galactic nuclei(AGN),the Milky Way and nearby galaxies,stars,exoplanets,Solar System objects,astrometry,and transients and variable sources.This review aims to provide a comprehensive overview of the CSST instruments,observational capabilities,data products,and scientific potential.
基金supported by the National Natural Science Foundation of China(21273206)the Natural Science Foundation of Henan Province(2010GGJS-110)
文摘In situ pressure-induced Raman spectral changes of 1-octyl-3-methyl imidazolium hexafluorophosphate([OMIM][PF6])have been investigated under the pressure up to 5.86 GPa at room temperature.The results indicated that[OMIM][PF6]experienced a phase transition at about4.12 GPa during compression,and it was thought as a phase transition of liquid to a superpressurized glass.Upon decompression,from the obvious change of Raman spectra of[OMIM][PF6]at about 0.48 GPa,it could be inferred that a decompression-induced disorder to order phase transition in[OMIM][PF6]occurred.The phase behavior of[OMIM][PF6]at low temperature under atmospheric pressure was also investigated in detail.The result showed that Raman spectra of[OMIM][PF6]varied slightly and no crystallization occurred upon cooling.These facts suggested that a disorder to order phase transition was induced by decompression in[OMIM][PF6],and[OMIM][PF6]served as a superpressurized glass under the pressure above4.12 GPa,which was similar to the glassy state at low temperature.
文摘Photothermal agents(PTAs)with ultra-high photothermal conversion efficiency(PCE)activated upon near-infrared(NIR)laser irradiation can heat up and destroy tumor cells under low-intensity laser excitation to allow safe and efficient tumor therapy.Herein,an organic PTA with an outstanding PCE of 89.6%is developed from rationally designed perylene diimide(PDI)with electron-donating cyclohexylamine moiety at the bay-positions of its skeleton and chiral phenethylamine(PEA)moiety at its N terminals,termed here PEAPDI.The strong intermolecular interaction between the PDI skeletons induced by PEA together with the intramolecular charge transfer from cyclohexylamine to PDI skeleton severely quenches the fluorescence emission from PEAPDI and significantly enhances its NIR absorption,resulting in super NIR–photothermal conversion.PEAPDI molecules are subsequently encapsulated within silica nanocapsules(SNCs),creating PEAPDI@SNC.Characterized by its small hydrodynamic diameter,monodispersity,high PDI encapsulation efficiency,colloidal stability,and biocompatibility,PEAPDI@SNC exhibits prolonged blood circulation and enhanced permeability and retention effect,enabling targeted accumulation at the tumor site.An in vivo study using a 4T1 tumor–bearing mice model illustrates the agent’s potent tumor ablation capability without side effects at low dosage under NIR laser irradiation(808 nm).The findings demonstrate PEAPDI@SNC’s significant potential as a PTA for tumor treatment.
基金This work is supported by the the National Natural Science Foundation of China under grant nos.11988101,11973049,11933004,11890694,12090040,12090042,12090043,12090044,11833002,11833006,12022304,11835057,11973052,11633005,12173007,11933001,11703035,U2031203,and U1531244the National Key R&D Program of China under grant nos.2019YFA0405100,2019YFA0405500,2019YFA0405502,2019YFA0405503,2019YFA0405504,2016YFA0400804,and 2019YFA0405000+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences,grant nos.XDB34020205 and XDB41000000H.Yan,H.L.,S.W.,and Hailong Yuan acknowledge support from the Youth Innovation Promotion Association of the Chinese Academy of Sciences(nos.2019060,Y202017,2019057,and 2020060,respectively).
文摘The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST),also known as the Guoshoujing Telescope,is a major national scientific facility for astronomical research located in Xinglong,China.Beginning with a pilot survey in 2011,LAMOST has been surveying the night sky for more than 10 years.The LAMOST survey covers various objects in the Universe,from normal stars to peculiar ones.
文摘We humans are always asking why.It seems to be our nature.How did we get here?Are we alone in the universe?How does the universe work?These are the questions we are still trying to answer,which also has been the ultimate goal of astronomy for thousands of years.For centuries,telescopes,being powerful tools for exploring the universe,have enabled us to probe beyond what we can reach on our own.Just this summer,an already-legendary telescope,the 6.5-m James Webb Space Telescope(JWST),has started to take astronomers a step closer to their ultimate goal.
