A method of digitally high pass filtering in frequency domain is proposed to eliminate the background noise of the decoded image in Fresnel zone plate scanning holography. The high pass filter is designed as a circula...A method of digitally high pass filtering in frequency domain is proposed to eliminate the background noise of the decoded image in Fresnel zone plate scanning holography. The high pass filter is designed as a circular stop, which should be suitable to suppressing the background noise significantly and remain much low frequency information of the object. The principle of high pass filtering is that the Fourier transform of the decoded image is multiplied with the high pass filter. Thus the frequency spectrum of the decoded image without the background noise is achieved. By inverse Fourier transform of the spectrum of the decoded image after multiplying operation, the decoded image without the background noise is obtained. Both of the computer simulations and the experimental results show that the contrast and the signal-to-noise ratio of the decoded image are significantly improved with digital filtering.展开更多
The equalization of Ti 6Al 4V alloy welded joint with base metal on corrosion resistance, strength and ductility was studied. The solidification microstructure is transformed from 650 μm columnar grains to 100 μm eq...The equalization of Ti 6Al 4V alloy welded joint with base metal on corrosion resistance, strength and ductility was studied. The solidification microstructure is transformed from 650 μm columnar grains to 100 μm equiaxed grains by scanning electron beam welding. The anodic polarization curve of 150 μm equiaxed grains coincides with that of base metal. Equal corrosion resistance between weld metal and base metal was obtained. Uniform microstructure and solute distribution are the basis of equalization. Corrosion rate of weld with 150 μm equiaxed grains is the lowest, 2.45 times lower than that of 650 μm columnar grains. Weld strength is 98% as much as that of base metal, yield strength ratio is 99.5%, which is 3.6% higher than that of base metal.展开更多
Let Ф（u ×v, k, Aa, Ac） be the largest possible number of codewords among all two- dimensional （u ×v, k, λa, λc） optical orthogonal codes. A 2-D （u× v, k, λa, λ）-OOC with Ф（u× v, k, λ...Let Ф（u ×v, k, Aa, Ac） be the largest possible number of codewords among all two- dimensional （u ×v, k, λa, λc） optical orthogonal codes. A 2-D （u× v, k, λa, λ）-OOC with Ф（u× v, k, λa, λc） codewords is said to be maximum. In this paper, the number of codewords of a maximum 2-D （u × v, 4, 1, 3）-OOC has been determined.展开更多
Scanning probe microscopy(SPM) stands out as one of the most powerful tools for characterizing the solid surface and the adsorbed molecules with ?ngstr?m resolution in real space. In particular, this unique technique ...Scanning probe microscopy(SPM) stands out as one of the most powerful tools for characterizing the solid surface and the adsorbed molecules with ?ngstr?m resolution in real space. In particular, this unique technique provides an unprecedented opportunity for directly probing the low-dimensional ices at surfaces. In this perspective, we first review the recent advances of scanning tunneling microscopy(STM) imaging of various two-dimensional(2 D) ice structures on metal[1-7], insulator[8-12], graphite[13-15] surfaces and under strong confinement[10, 16-19]. We then introduce that noncontact atomic-force microscopy(AFM) with a CO-terminated tip enables atomic imaging of a genuine 2 D ice grown on a hydrophobic Au(111) surface with minimal perturbation[20], paying particular attention to the growth processes at the edges of 2 D ice. In the end, we present an outlook on the future applications of 2 D ice as well as the relation between the 2 D and 3 D ice growth.展开更多
This paper combines improved Hamming codes and parity codes to assure the reliability of memory in presence of multiple bit upsets with low cost overhead.The redundancy bits of improved Hamming codes will be appended ...This paper combines improved Hamming codes and parity codes to assure the reliability of memory in presence of multiple bit upsets with low cost overhead.The redundancy bits of improved Hamming codes will be appended at the end of data bits,which eliminates the overhead of interspersing the redundancy bits at the encoder and decoder.The reliability of memory is further enhanced by the layout architecture of redundancy bits and data bits.The proposed scheme has been implemented in Verilog and synthesized using the Synopsys tools.The results reveal that the proposed method has about 19% less area penalties and 13% less power consumption comparing with the current two-dimensional error codes,and its latency of encoder and decoder is 63% less than that of Hamming codes.展开更多
Two-dimensional(2 D) materials attracted substantial attention due to their extraordinary physical properties resulting from the unique atomic thickness. 2 D materials could be considered as material systems with flat...Two-dimensional(2 D) materials attracted substantial attention due to their extraordinary physical properties resulting from the unique atomic thickness. 2 D materials could be considered as material systems with flat surfaces at both sides, while the van der Waals gap is a natural out-of-plane interface between two monolayers. However, defects are inevitably presented and often cause significant surface and interface reconstruction, which modify the physical properties of the materials being investigated. In this review article, we reviewed the effort achieved in probing the defect structures and the reconstruction of surface and interface in novel 2 D materials through aberration corrected low voltage scanning transmission electron microscopy(LVSTEM). The LVSTEM technique enables us to unveil the intrinsic atomic structure of defects atom-by-atom, and even directly visualize the dynamical reconstruction process with single atom precision. The effort in understanding the defect structures and their contributions in the surface and interface reconstructions in 2 D materials shed light on the origin of their novel physical phenomenon, and also pave the way for defect engineering in future potential applications.展开更多
Superconducting quantum interference devices(SQUIDs)are directly sensitive to magnetic flux.Nano-fabricated SQUID chip with miniaturized superconducting circuits can be further utilized as scanning probes for imaging ...Superconducting quantum interference devices(SQUIDs)are directly sensitive to magnetic flux.Nano-fabricated SQUID chip with miniaturized superconducting circuits can be further utilized as scanning probes for imaging of materials.Scanning SQUID microscopy(SSM)combines both high spatial resolution and high magnetic field sensitivity and is especially suitable for studying low dimensional materials with small sensing volumes.Here,we briefly review the fabrication of different types of nano-SQUIDs and the recent progress of utilizing them for scanning microscopy of quantum materials.We focus on but are not limited to topological states,unconventional superconductivity and exotic magnetism with a particular interest in two-dimensional materials.The magnet-ometry,susceptometry and current imaging modes of the SSM coupled with the external tuning of the material by magnetic field,electrical field gating and strain reveals a multitude of information beyond the scopes of charge-sensing probes.展开更多
The desert plant Rhazya stricta has anticancer and antimicrobial properties, and is widely used in indigenous medicines of Saudi Arabia. However, the therapeutic benefits rely on an accurate identification of this spe...The desert plant Rhazya stricta has anticancer and antimicrobial properties, and is widely used in indigenous medicines of Saudi Arabia. However, the therapeutic benefits rely on an accurate identification of this species. The authenticity of R. stricta and other medicinal plants and herbs procured from local markets can be questionable due to a lack of clear phenotypic traits. DNA barcoding is an emerging technology for rapid and accurate species identification. In this study, six candidate chloroplastid barcodes were investigated for the authentication of R. stricta. We compared the DNA sequences from fifty locally collected and five market samples of R. stricta with database sequences of R. stricta and seven closely related species. We found that the coding regions matK, rbcL, rpoB, and rpoC1 were highly similar among the taxa. By contrast, the intergenic spacers psbK-psbI and atpF-atpH were variable loci distinct for the medicinal plant R. stricta. psbK-psbI clearly discriminated R. stricta samples as an efficient single locus marker, whereas a two-locus marker combination comprising psbK-psbI + atpF-atpH was also promising according to results from the Basic Local Alignment Search Tool and a maximum likelihood gene tree generated using PHyML. Two-dimensional DNA barcodes (i.e., QR codes) for the psbK-psbI and psbK-psbI + atpF-atpH regions were created for the validation of fresh or dried R. stricta samples.展开更多
This paper briefly introduces the characteristics and structure of symbol QR two-dimensional code, a detailed analysis of the image processing method to identify QR code of the whole process, and the bilinear mapping ...This paper briefly introduces the characteristics and structure of symbol QR two-dimensional code, a detailed analysis of the image processing method to identify QR code of the whole process, and the bilinear mapping method is applied to image correction, the final steps of decoding are given. The actual test results show that, the design algorithm has theoretical and practical, this recognition system can correctly read QR code, and has high recognition rate and recognition speed, has practical value and application prospect.展开更多
In the self-built fruit and vegetable sorting warehouse of Lushang Group,the system is automatically scanning the QR code for agricultural product and conducts pesticide residue testing on fruits and vegetables;new pr...In the self-built fruit and vegetable sorting warehouse of Lushang Group,the system is automatically scanning the QR code for agricultural product and conducts pesticide residue testing on fruits and vegetables;new products from foreign trade factories will be directly transported to Ginza Supermarket through the“Direct Express for Domestic Product”channel,and will be shelved on the“Lushang Life”service platform within 48 hours;in front of the campus intelligent milk cabinet independently launched by Lushang Technology,students receive pasteurized milk by brushing their faces,and the data about milk source farms and sterilization parameters are sent to the parents simultaneously.This is the daily scenario of digital applications by Lushang Group’s full supply chain management.展开更多
Although electrostatic bonding between chalcogen(Ch)atoms(O,S,Se,and Te)and nitrogen(N)has emerged as a powerful driving force in the fabrication of supramolecular structures;this noncovalent bond has not yet been use...Although electrostatic bonding between chalcogen(Ch)atoms(O,S,Se,and Te)and nitrogen(N)has emerged as a powerful driving force in the fabrication of supramolecular structures;this noncovalent bond has not yet been used to link polymers to form networks.In this study,we took advantage of additive enthalpy in forming multipoint noncovalent bonds to construct a two-dimensional(2D)network via the hierarchical on-surface synthesis of linear polymer chains,followed by multipoint S···N and S···H bonding.When 4,7-dibromobenzo[c][1,2,5]thiadiazole was used,only short oligomers with embedded bromine atoms and cross-linked byproducts were formed on Ag(111)or Au(111)surfaces after multiple annealing procedures,and no 2D network was observed.By changing the precursor to a similar iodinesubstituted molecule,long linear polymers were generated and assembled with iodine atoms on Au(111)after annealing at 523 K.After annealing at 603 K,iodine atoms were desorbed and polymer chains were assembled via multipoint noncovalent bonding.The 2D network remained intact after annealing at 653 K,demonstrating its high thermostability.The multipoint noncovalent bonds were investigated by the combination of scanning tunneling microscopy,noncontact atomic force microscopy,and density functional theory calculations,which revealed that S···N and S···H bonding were the driving forces to construct thermostable and orderly 2D networks.展开更多
Spin crossover(SCO)is commonly accompanied by a synchronous phase transition.A few phase transitioncoupled SCO compounds have been reported,yet the synergy between SCO and phase transition on different time scales has...Spin crossover(SCO)is commonly accompanied by a synchronous phase transition.A few phase transitioncoupled SCO compounds have been reported,yet the synergy between SCO and phase transition on different time scales has not been explored.Herein,we report an[Fe(H-5-Cl-thsa-Et)(5-Cl-thsa-Et)]·H2O(1·H2O;H2-5-Cl-thsa-Et=5-chloro-salicylaldehyde ethylthiosemicarbazone)Fe(III)complex that displays a two-dimensional supramolecular structure and SCO behavior above room temperature.Its dehydrated form1 exhibits a two-step spin transition with aplateau in the temperature-dependent magnetization(M−T)curve at room temperature and a 51 K thermal hysteresis loop(Tc↑↓=299/248 K)at a rate of 5 K/min.The improved SCOperformance in 1 could be attributed to the stronger intralayer but weaker interlayer interactions,which is supported by single-crystal structural analysis and density functional theory calculations.Remarkably,complex 1 displays an unusual scan rate-dependent SCO behavior at rates of 0.5−30 K/min,in whichM−T curveplateaus appear at lower scan rates(<10 K/min)but vanish at faster scan rates(≥10 K/min).Scan rate-dependent differential scanning calorimetry,powder X-ray diffractometry,timedependent magnetic moment decays,and infrared spectroscopy consistently reveal that the slow structural relaxation is coupled with a slowcrystallographic phase transition,which is the mechanism for the unusual scan rate-dependent SCO.展开更多
文摘A method of digitally high pass filtering in frequency domain is proposed to eliminate the background noise of the decoded image in Fresnel zone plate scanning holography. The high pass filter is designed as a circular stop, which should be suitable to suppressing the background noise significantly and remain much low frequency information of the object. The principle of high pass filtering is that the Fourier transform of the decoded image is multiplied with the high pass filter. Thus the frequency spectrum of the decoded image without the background noise is achieved. By inverse Fourier transform of the spectrum of the decoded image after multiplying operation, the decoded image without the background noise is obtained. Both of the computer simulations and the experimental results show that the contrast and the signal-to-noise ratio of the decoded image are significantly improved with digital filtering.
文摘The equalization of Ti 6Al 4V alloy welded joint with base metal on corrosion resistance, strength and ductility was studied. The solidification microstructure is transformed from 650 μm columnar grains to 100 μm equiaxed grains by scanning electron beam welding. The anodic polarization curve of 150 μm equiaxed grains coincides with that of base metal. Equal corrosion resistance between weld metal and base metal was obtained. Uniform microstructure and solute distribution are the basis of equalization. Corrosion rate of weld with 150 μm equiaxed grains is the lowest, 2.45 times lower than that of 650 μm columnar grains. Weld strength is 98% as much as that of base metal, yield strength ratio is 99.5%, which is 3.6% higher than that of base metal.
基金Supported by the National Natural Science Foundation of China(61071221,10831002)
文摘Let Ф（u ×v, k, Aa, Ac） be the largest possible number of codewords among all two- dimensional （u ×v, k, λa, λc） optical orthogonal codes. A 2-D （u× v, k, λa, λ）-OOC with Ф（u× v, k, λa, λc） codewords is said to be maximum. In this paper, the number of codewords of a maximum 2-D （u × v, 4, 1, 3）-OOC has been determined.
文摘Scanning probe microscopy(SPM) stands out as one of the most powerful tools for characterizing the solid surface and the adsorbed molecules with ?ngstr?m resolution in real space. In particular, this unique technique provides an unprecedented opportunity for directly probing the low-dimensional ices at surfaces. In this perspective, we first review the recent advances of scanning tunneling microscopy(STM) imaging of various two-dimensional(2 D) ice structures on metal[1-7], insulator[8-12], graphite[13-15] surfaces and under strong confinement[10, 16-19]. We then introduce that noncontact atomic-force microscopy(AFM) with a CO-terminated tip enables atomic imaging of a genuine 2 D ice grown on a hydrophobic Au(111) surface with minimal perturbation[20], paying particular attention to the growth processes at the edges of 2 D ice. In the end, we present an outlook on the future applications of 2 D ice as well as the relation between the 2 D and 3 D ice growth.
基金Sponsored by the Opening Project of National Key Laboratory of Science and Technology on Reliability PhysicsApplication Technology of Electrical Component(Grant No.ZHD200903)
文摘This paper combines improved Hamming codes and parity codes to assure the reliability of memory in presence of multiple bit upsets with low cost overhead.The redundancy bits of improved Hamming codes will be appended at the end of data bits,which eliminates the overhead of interspersing the redundancy bits at the encoder and decoder.The reliability of memory is further enhanced by the layout architecture of redundancy bits and data bits.The proposed scheme has been implemented in Verilog and synthesized using the Synopsys tools.The results reveal that the proposed method has about 19% less area penalties and 13% less power consumption comparing with the current two-dimensional error codes,and its latency of encoder and decoder is 63% less than that of Hamming codes.
基金the support from National Natural Science Foundation of China(No.11974156)Guangdong International Science Collaboration Project(No.2019A050510001)the assistance of SUSTech Core Research Facilities,especially technical support from Pico-Centre that receives support from Presidential fund and Development and Reform Commission of Shenzhen。
文摘Two-dimensional(2 D) materials attracted substantial attention due to their extraordinary physical properties resulting from the unique atomic thickness. 2 D materials could be considered as material systems with flat surfaces at both sides, while the van der Waals gap is a natural out-of-plane interface between two monolayers. However, defects are inevitably presented and often cause significant surface and interface reconstruction, which modify the physical properties of the materials being investigated. In this review article, we reviewed the effort achieved in probing the defect structures and the reconstruction of surface and interface in novel 2 D materials through aberration corrected low voltage scanning transmission electron microscopy(LVSTEM). The LVSTEM technique enables us to unveil the intrinsic atomic structure of defects atom-by-atom, and even directly visualize the dynamical reconstruction process with single atom precision. The effort in understanding the defect structures and their contributions in the surface and interface reconstructions in 2 D materials shed light on the origin of their novel physical phenomenon, and also pave the way for defect engineering in future potential applications.
基金Yihua Wang would like to acknowledge support by Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the National Key R&D Program of China(Grant No.2021YFA1400100)+2 种基金the National Natural Science Foundation of China(Grant No.12150003)Hao Li thanks the National Natural Science Foundation of China(Grant No.62201556)the Shanghai Pujiang Program(Grant No.22PJ1415200)for financial support.
文摘Superconducting quantum interference devices(SQUIDs)are directly sensitive to magnetic flux.Nano-fabricated SQUID chip with miniaturized superconducting circuits can be further utilized as scanning probes for imaging of materials.Scanning SQUID microscopy(SSM)combines both high spatial resolution and high magnetic field sensitivity and is especially suitable for studying low dimensional materials with small sensing volumes.Here,we briefly review the fabrication of different types of nano-SQUIDs and the recent progress of utilizing them for scanning microscopy of quantum materials.We focus on but are not limited to topological states,unconventional superconductivity and exotic magnetism with a particular interest in two-dimensional materials.The magnet-ometry,susceptometry and current imaging modes of the SSM coupled with the external tuning of the material by magnetic field,electrical field gating and strain reveals a multitude of information beyond the scopes of charge-sensing probes.
文摘The desert plant Rhazya stricta has anticancer and antimicrobial properties, and is widely used in indigenous medicines of Saudi Arabia. However, the therapeutic benefits rely on an accurate identification of this species. The authenticity of R. stricta and other medicinal plants and herbs procured from local markets can be questionable due to a lack of clear phenotypic traits. DNA barcoding is an emerging technology for rapid and accurate species identification. In this study, six candidate chloroplastid barcodes were investigated for the authentication of R. stricta. We compared the DNA sequences from fifty locally collected and five market samples of R. stricta with database sequences of R. stricta and seven closely related species. We found that the coding regions matK, rbcL, rpoB, and rpoC1 were highly similar among the taxa. By contrast, the intergenic spacers psbK-psbI and atpF-atpH were variable loci distinct for the medicinal plant R. stricta. psbK-psbI clearly discriminated R. stricta samples as an efficient single locus marker, whereas a two-locus marker combination comprising psbK-psbI + atpF-atpH was also promising according to results from the Basic Local Alignment Search Tool and a maximum likelihood gene tree generated using PHyML. Two-dimensional DNA barcodes (i.e., QR codes) for the psbK-psbI and psbK-psbI + atpF-atpH regions were created for the validation of fresh or dried R. stricta samples.
文摘This paper briefly introduces the characteristics and structure of symbol QR two-dimensional code, a detailed analysis of the image processing method to identify QR code of the whole process, and the bilinear mapping method is applied to image correction, the final steps of decoding are given. The actual test results show that, the design algorithm has theoretical and practical, this recognition system can correctly read QR code, and has high recognition rate and recognition speed, has practical value and application prospect.
基金This project is supported by Postdoctoral Science Research Foundation of China （20060390859） and National Nature Science Foundation of China （69555011）.
文摘In the self-built fruit and vegetable sorting warehouse of Lushang Group,the system is automatically scanning the QR code for agricultural product and conducts pesticide residue testing on fruits and vegetables;new products from foreign trade factories will be directly transported to Ginza Supermarket through the“Direct Express for Domestic Product”channel,and will be shelved on the“Lushang Life”service platform within 48 hours;in front of the campus intelligent milk cabinet independently launched by Lushang Technology,students receive pasteurized milk by brushing their faces,and the data about milk source farms and sterilization parameters are sent to the parents simultaneously.This is the daily scenario of digital applications by Lushang Group’s full supply chain management.
基金supported by the National Natural Science Foundation of China(grant nos.22002044,21925201,22161160319,22201073,and 21978049)Shanghai Municipal Science and Technology Major Project,China(grant no.2018SHZDZX03)+2 种基金China Postdoctoral Science Foundation(grant nos.2022M711035 and 2021M702188)the Programme of Introducing Talents of Discipline to Universities,China(grant no.B16017)the Fundamental Research Funds for the Central Universities of China.We thank the Research Center of Analysis and Testing of East China University of Science and Technology for help with the characterization of our fabrications.
文摘Although electrostatic bonding between chalcogen(Ch)atoms(O,S,Se,and Te)and nitrogen(N)has emerged as a powerful driving force in the fabrication of supramolecular structures;this noncovalent bond has not yet been used to link polymers to form networks.In this study,we took advantage of additive enthalpy in forming multipoint noncovalent bonds to construct a two-dimensional(2D)network via the hierarchical on-surface synthesis of linear polymer chains,followed by multipoint S···N and S···H bonding.When 4,7-dibromobenzo[c][1,2,5]thiadiazole was used,only short oligomers with embedded bromine atoms and cross-linked byproducts were formed on Ag(111)or Au(111)surfaces after multiple annealing procedures,and no 2D network was observed.By changing the precursor to a similar iodinesubstituted molecule,long linear polymers were generated and assembled with iodine atoms on Au(111)after annealing at 523 K.After annealing at 603 K,iodine atoms were desorbed and polymer chains were assembled via multipoint noncovalent bonding.The 2D network remained intact after annealing at 653 K,demonstrating its high thermostability.The multipoint noncovalent bonds were investigated by the combination of scanning tunneling microscopy,noncontact atomic force microscopy,and density functional theory calculations,which revealed that S···N and S···H bonding were the driving forces to construct thermostable and orderly 2D networks.
基金supported by the National Natural Science Foundation of China(NSFCnos.21971124 and 22035003).
文摘Spin crossover(SCO)is commonly accompanied by a synchronous phase transition.A few phase transitioncoupled SCO compounds have been reported,yet the synergy between SCO and phase transition on different time scales has not been explored.Herein,we report an[Fe(H-5-Cl-thsa-Et)(5-Cl-thsa-Et)]·H2O(1·H2O;H2-5-Cl-thsa-Et=5-chloro-salicylaldehyde ethylthiosemicarbazone)Fe(III)complex that displays a two-dimensional supramolecular structure and SCO behavior above room temperature.Its dehydrated form1 exhibits a two-step spin transition with aplateau in the temperature-dependent magnetization(M−T)curve at room temperature and a 51 K thermal hysteresis loop(Tc↑↓=299/248 K)at a rate of 5 K/min.The improved SCOperformance in 1 could be attributed to the stronger intralayer but weaker interlayer interactions,which is supported by single-crystal structural analysis and density functional theory calculations.Remarkably,complex 1 displays an unusual scan rate-dependent SCO behavior at rates of 0.5−30 K/min,in whichM−T curveplateaus appear at lower scan rates(<10 K/min)but vanish at faster scan rates(≥10 K/min).Scan rate-dependent differential scanning calorimetry,powder X-ray diffractometry,timedependent magnetic moment decays,and infrared spectroscopy consistently reveal that the slow structural relaxation is coupled with a slowcrystallographic phase transition,which is the mechanism for the unusual scan rate-dependent SCO.
