Si based single electron transistor (SET) is fabricated successfully on p type SIMOX substrate,based on electron beam (EB) lithography,reactive ion etching (RIE) and thermal oxidation.In particular,using thermal oxi...Si based single electron transistor (SET) is fabricated successfully on p type SIMOX substrate,based on electron beam (EB) lithography,reactive ion etching (RIE) and thermal oxidation.In particular,using thermal oxidation and etching off the oxide layer,a one dimensional Si quantum wire can be converted into several quantum dots inside quantum wire in connection with the source and drain regions.The differential conductance (d I ds /d V ds ) oscillations and the Coulomb staircases in the source drain current ( I ds ) are shown clearly dependent on the source drain voltage at 5 3K.The I ds V gs (gate voltage) oscillations are observed from the I ds V gs characteristics as a function of V gs at different temperatures and various values of V ds .For a SET whose total capacitance is about 9 16aF,the I ds V gs oscillations can be observed at 77K.展开更多
The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cu...The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cutting parameters were conducted. Cutting temperature was measured by FLIR A315 infrared thermal imager. Tool wear was measured by scanning electron microscope(SEM). The numerical model of heat flux considering tool wear generated in cutting zone was established. Then two-step finite element method(FEM) simulations matching the experimental conditions were carried out to simulate the thermal deformation. In addition, the tests of deformation of tool system were performed to verify previous simulation results. And then the influence of cutting parameters on thermal deformation was investigated. The results show that the temperature and thermal deformation from simulations agree well with the results from experiments in the same conditions. The maximum thermal deformation of tool reaches to 7 μm. The average flank wear width and cutting speed are the dominant factors affecting thermal deformation, and the effective way to decrease the thermal deformation of tool is to control the tool wear and the cutting speed.展开更多
The interracial electron transfer （IET） dynamics of single CdSe core/multilayer shell （CdS2MLZnCdS1MLZnSIML） quantum dots （QDs） on the （110） surface of a futile TiO2 single crystal and TiO2 nanoparticles have ...The interracial electron transfer （IET） dynamics of single CdSe core/multilayer shell （CdS2MLZnCdS1MLZnSIML） quantum dots （QDs） on the （110） surface of a futile TiO2 single crystal and TiO2 nanoparticles have been compared. The fluorescence decay rates of single QDs on TiO2 are faster than those on glass, an insulating substrate, due to lET from the QDs to TiO2. Whereas the average IET rates are similar for QDs on the single crystal and nanoparticles, the distribution of lET rates is much broader in the latter, indicating a broad distribution of QD adsorption sites on the TiO2 nanoparticles.展开更多
We investigate the low-energy electronic structure ofa Weyl semimetal quantum dot （QD） with a simple model Hamiltonian with only two Weyl points. Distinguished from the semiconductor and topological insulator QDs, t...We investigate the low-energy electronic structure ofa Weyl semimetal quantum dot （QD） with a simple model Hamiltonian with only two Weyl points. Distinguished from the semiconductor and topological insulator QDs, there exist both surface and bulk states near the Fermi level in Weyl semimetal QDs. The surface state, distributed near the side surface of the QD, contributes a circular persistent current, an orbital magnetic moment, and a chiral spin polarization with spin-current locking. There are always surface states even for a strong magnetic field, even though a given surface state gradually evolves into a Landau level with increasing magnetic field. It indicates that these unique properties can be tuned via the QD size. In addition, we show the correspondence to the electronic structures of a three-dimensional Weyl semimetal, such as Wey[ point and Fermi arc. Because a QD has the largest surface-to-volume ratio, it provides a new platform to verify Weyl semimetal by separating and detecting the signals of surface states. Besides, the study of Weyl QDs is also necessary for potential applications in nanoelectronics.展开更多
The design and synthesis of bio-nano hybrid materials can not only provide new materials with novel properties, but also advance our fundamental understanding of interactions between biomolecules and their abiotic cou...The design and synthesis of bio-nano hybrid materials can not only provide new materials with novel properties, but also advance our fundamental understanding of interactions between biomolecules and their abiotic counterparts. Here, we report a new approach to achieving such a goal by growing CdS quantum dots （QDs） within single crystals of lysozyme protein. This bio-nano hybrid emitted much stronger red fluorescence than its counterpart without the crystal, and such fluorescence properties could be either enhanced or suppressed by the addition of Ag（I） or Hg（II）, respectively. The three-dimensional incorporation of CdS QDs within the lysozyme crystals was revealed by scanning transmission electron microscopy with electron tomography. More importantl~ since our approach did not disrupt the crystalline nature of the lysozyme crystals, the metal and protein interactions were able to be studied by X-ray crystallography, thus providing insight into the role of Cd（II） in the CdS QDs formation.展开更多
文摘Si based single electron transistor (SET) is fabricated successfully on p type SIMOX substrate,based on electron beam (EB) lithography,reactive ion etching (RIE) and thermal oxidation.In particular,using thermal oxidation and etching off the oxide layer,a one dimensional Si quantum wire can be converted into several quantum dots inside quantum wire in connection with the source and drain regions.The differential conductance (d I ds /d V ds ) oscillations and the Coulomb staircases in the source drain current ( I ds ) are shown clearly dependent on the source drain voltage at 5 3K.The I ds V gs (gate voltage) oscillations are observed from the I ds V gs characteristics as a function of V gs at different temperatures and various values of V ds .For a SET whose total capacitance is about 9 16aF,the I ds V gs oscillations can be observed at 77K.
基金Project(51175122)supported by the National Natural Science Foundation of China
文摘The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cutting parameters were conducted. Cutting temperature was measured by FLIR A315 infrared thermal imager. Tool wear was measured by scanning electron microscope(SEM). The numerical model of heat flux considering tool wear generated in cutting zone was established. Then two-step finite element method(FEM) simulations matching the experimental conditions were carried out to simulate the thermal deformation. In addition, the tests of deformation of tool system were performed to verify previous simulation results. And then the influence of cutting parameters on thermal deformation was investigated. The results show that the temperature and thermal deformation from simulations agree well with the results from experiments in the same conditions. The maximum thermal deformation of tool reaches to 7 μm. The average flank wear width and cutting speed are the dominant factors affecting thermal deformation, and the effective way to decrease the thermal deformation of tool is to control the tool wear and the cutting speed.
基金supported by the National Science Foundation (CHE-0848556)the donors of the Petroleum Research Fund of the American Chemical Society (PRF #49286-ND6)
文摘The interracial electron transfer （IET） dynamics of single CdSe core/multilayer shell （CdS2MLZnCdS1MLZnSIML） quantum dots （QDs） on the （110） surface of a futile TiO2 single crystal and TiO2 nanoparticles have been compared. The fluorescence decay rates of single QDs on TiO2 are faster than those on glass, an insulating substrate, due to lET from the QDs to TiO2. Whereas the average IET rates are similar for QDs on the single crystal and nanoparticles, the distribution of lET rates is much broader in the latter, indicating a broad distribution of QD adsorption sites on the TiO2 nanoparticles.
基金supported by the National Natural Science Foundation of China(Grants Nos.11747122,11274364,and 11574007)the National Basic Research Program of China(Grant Nos.2017YFA0303301,and2015CB921102)+1 种基金the Natural Science Foundation of Shandong Province(Grant No.ZR2018PA007)the Doctoral Foundation of University of Jinan(Grant No.160100147)
文摘We investigate the low-energy electronic structure ofa Weyl semimetal quantum dot （QD） with a simple model Hamiltonian with only two Weyl points. Distinguished from the semiconductor and topological insulator QDs, there exist both surface and bulk states near the Fermi level in Weyl semimetal QDs. The surface state, distributed near the side surface of the QD, contributes a circular persistent current, an orbital magnetic moment, and a chiral spin polarization with spin-current locking. There are always surface states even for a strong magnetic field, even though a given surface state gradually evolves into a Landau level with increasing magnetic field. It indicates that these unique properties can be tuned via the QD size. In addition, we show the correspondence to the electronic structures of a three-dimensional Weyl semimetal, such as Wey[ point and Fermi arc. Because a QD has the largest surface-to-volume ratio, it provides a new platform to verify Weyl semimetal by separating and detecting the signals of surface states. Besides, the study of Weyl QDs is also necessary for potential applications in nanoelectronics.
基金This work was supported by the US National Science Foundation （Nos. CMMI 0749028 and DMR-0117792）. The authors thank C. Lei and W. Swiech for help with the STEM imaging, C~ M. Bee and D. Zhang for fluorescence microscopic measurements, S. M. Nie for the use of Nuance system and A. M. Smith for insightful discussions. S. H. and I. M. R. acknowledge support from the US Department of Energy （grant No. DE-FC36-05GO15064）. STEM experiments were carried out in part in the Frederick Seitz Materials Research Laboratory Central Facilities, University of Illinois. X-ray crystallographic data for this study were measured at beamline X12C of the National Synchrotron Light Source, Brookhaven National Laboratory. Financial support comes principally from the Offices of Biological and Environmental Research and of Basic Energy Sciences of the US Department of Energy, and from the National Center for Research Resources （No. P41RR012408） and the National Institute of General Medical Sciences （No. P41GM103473） of the National Institutes of Health.
文摘The design and synthesis of bio-nano hybrid materials can not only provide new materials with novel properties, but also advance our fundamental understanding of interactions between biomolecules and their abiotic counterparts. Here, we report a new approach to achieving such a goal by growing CdS quantum dots （QDs） within single crystals of lysozyme protein. This bio-nano hybrid emitted much stronger red fluorescence than its counterpart without the crystal, and such fluorescence properties could be either enhanced or suppressed by the addition of Ag（I） or Hg（II）, respectively. The three-dimensional incorporation of CdS QDs within the lysozyme crystals was revealed by scanning transmission electron microscopy with electron tomography. More importantl~ since our approach did not disrupt the crystalline nature of the lysozyme crystals, the metal and protein interactions were able to be studied by X-ray crystallography, thus providing insight into the role of Cd（II） in the CdS QDs formation.
