The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the...The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.展开更多
A kind of thrombus-targeted lipid-coated microbubbles were prepared, and the target prop- erty of the microbubbles and the effects of different methods detecting thrombosis in vessels were ob- served. Phospholipid-coa...A kind of thrombus-targeted lipid-coated microbubbles were prepared, and the target prop- erty of the microbubbles and the effects of different methods detecting thrombosis in vessels were ob- served. Phospholipid-coated microbubbles were prepared by membrane-hydration method. Throm- bus-targeted lipid-coated fluorocarbon microbubbles were labeled with specific fluorescence and then integrated to the thrombus in vivo and ex vivo through an avidin biotin system. The thrombus was im- mediately observed for the distribution and property of the thrombus-targeted microbubbles under the optical microscope, fluorescence microscope and transmission electron microscope. The carotid throm- bosis models were set up in rabbits, and the effects of different methods detecting thrombosis in vessels were observed. The diameter of the phospholipid-coated microbubbles was 0.8-2.5μm, and even reached nanoscale in some of them. The zeta electric potential was about -11 mV and the concentration was about 1.08×10μmL. Immunofluorescence of rapid frozen sections in vivo and ex vivo showed that massive targeted lipid-coated microbubbles flocked around fresh blood clots and some aggregated within them under the light and fluorescence microscope. The number of aggregated microbubbles ex vivo was greater than that observed in the experiment in vivo, and the fluorescence observed in the ex- periment ex vivo was stronger than that in the experiment in vivo. The same imaging was observed un- der the electron microscope. Models of carotid thrombosis in rabbits were established successfully. Ef- fects of detecting thrombosis by means of thrombosis-targeted microbubble ultrasonoraphy and Sono Vue ultrasonography in vessels were more satisfactory than those by Color Doplor Flow Imaging （CDFI）, ordinary microbubbles and Three Dimensions-time of flight MR angiography （3D-TOF-MRA） （P〈0.01）. Compared to ordinary microbubbles ultrasonography, thrombosis-targeted microbubbles ultrasonography had the advantages whenever in imaging quality or in imaging time. Thrombus-targeted phospholipid-coated microbubbles were prepared successfully by membrane-hydration method. They could aggregate rapidly in fresh blood clots and enter deep into the internal part of the thrombus both in vivo and ex vivo, and had the targeted property of strongly conjugating with the thrombus. Compared to other thrombosis detection methods, ultrasonography with thrombosis-targeted microbubbles has obvious advantages in detecting thrombosis in vessels, mainly in： non-invasiveness, safety, good image quality, accuracy, and longer imaging time.展开更多
We have investigated the doping behavior of rare earth element holmium （Ho3＋） in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO （x=0.0, 0.04, and 0.05） thin films deposite...We have investigated the doping behavior of rare earth element holmium （Ho3＋） in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO （x=0.0, 0.04, and 0.05） thin films deposited on Si（100） substrate by thermal evaporation technique were studied. The ceramic targets were prepared by conventional solid state ceramic technique. The pallets used as target were final sintered at 900℃ in the presence of N2 atmosphere. The experimental results of X-ray diffraction （XRD） spectra, surface morphology, and magnetic properties show that the Ho3＋ doped ZnO thin films has a strong influence on the materials properties. The higher angle shift in peak position and most preferred （101） orientation were observed in XRD pattern. These spectra confirmed the substitution of Ho3＋ in ZnO lattice. The surface morphology and stoichiometry for both bulk and thin films were analyzed by scanning electron microscopy and energy dispersive spectroscopy. It was observed that grain size decreases with the increase of Ho3＋. Room temperature ferromagnetism was observed for Zn0.95Ho0.050 films. The ferromagnetism might be attributed to the substitution of Ho ions for Zn2＋ in ZnO lattices.展开更多
文摘The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.
基金supported by National Natural Science Foundation of China (No. 30672207)
文摘A kind of thrombus-targeted lipid-coated microbubbles were prepared, and the target prop- erty of the microbubbles and the effects of different methods detecting thrombosis in vessels were ob- served. Phospholipid-coated microbubbles were prepared by membrane-hydration method. Throm- bus-targeted lipid-coated fluorocarbon microbubbles were labeled with specific fluorescence and then integrated to the thrombus in vivo and ex vivo through an avidin biotin system. The thrombus was im- mediately observed for the distribution and property of the thrombus-targeted microbubbles under the optical microscope, fluorescence microscope and transmission electron microscope. The carotid throm- bosis models were set up in rabbits, and the effects of different methods detecting thrombosis in vessels were observed. The diameter of the phospholipid-coated microbubbles was 0.8-2.5μm, and even reached nanoscale in some of them. The zeta electric potential was about -11 mV and the concentration was about 1.08×10μmL. Immunofluorescence of rapid frozen sections in vivo and ex vivo showed that massive targeted lipid-coated microbubbles flocked around fresh blood clots and some aggregated within them under the light and fluorescence microscope. The number of aggregated microbubbles ex vivo was greater than that observed in the experiment in vivo, and the fluorescence observed in the ex- periment ex vivo was stronger than that in the experiment in vivo. The same imaging was observed un- der the electron microscope. Models of carotid thrombosis in rabbits were established successfully. Ef- fects of detecting thrombosis by means of thrombosis-targeted microbubble ultrasonoraphy and Sono Vue ultrasonography in vessels were more satisfactory than those by Color Doplor Flow Imaging （CDFI）, ordinary microbubbles and Three Dimensions-time of flight MR angiography （3D-TOF-MRA） （P〈0.01）. Compared to ordinary microbubbles ultrasonography, thrombosis-targeted microbubbles ultrasonography had the advantages whenever in imaging quality or in imaging time. Thrombus-targeted phospholipid-coated microbubbles were prepared successfully by membrane-hydration method. They could aggregate rapidly in fresh blood clots and enter deep into the internal part of the thrombus both in vivo and ex vivo, and had the targeted property of strongly conjugating with the thrombus. Compared to other thrombosis detection methods, ultrasonography with thrombosis-targeted microbubbles has obvious advantages in detecting thrombosis in vessels, mainly in： non-invasiveness, safety, good image quality, accuracy, and longer imaging time.
文摘We have investigated the doping behavior of rare earth element holmium （Ho3＋） in ZnO semiconductor. The structural, microstructure, and magnetic properties of Zn1-xHoxO （x=0.0, 0.04, and 0.05） thin films deposited on Si（100） substrate by thermal evaporation technique were studied. The ceramic targets were prepared by conventional solid state ceramic technique. The pallets used as target were final sintered at 900℃ in the presence of N2 atmosphere. The experimental results of X-ray diffraction （XRD） spectra, surface morphology, and magnetic properties show that the Ho3＋ doped ZnO thin films has a strong influence on the materials properties. The higher angle shift in peak position and most preferred （101） orientation were observed in XRD pattern. These spectra confirmed the substitution of Ho3＋ in ZnO lattice. The surface morphology and stoichiometry for both bulk and thin films were analyzed by scanning electron microscopy and energy dispersive spectroscopy. It was observed that grain size decreases with the increase of Ho3＋. Room temperature ferromagnetism was observed for Zn0.95Ho0.050 films. The ferromagnetism might be attributed to the substitution of Ho ions for Zn2＋ in ZnO lattices.
