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Manifold learning of four-dimensional scanning transmission electron microscopy

npj Computational Materials 2019年第1期5卷 1097-1104页

作者： Xin Li Ondrej E.Dyck Mark P.Oxley Andrew R.Lupini Leland McInnes john healy Stephen Jesse Sergei V.Kalinin Center for Nanophase Materials Sciences Oak Ridge National LaboratoryOak RidgeTN 37831USA Institute for Functional Imaging of Materials Oak Ridge National LaboratoryOak RidgeTN 37831USA Tutte Institute for Mathematics and Computing OttawaCanada

Four-dimensional scanning transmission electron microscopy(4D-STEM)of local atomic diffraction patterns is emerging as a powerful technique for probing intricate details of atomic structure and atomic electric ***,efficient processing and interpretation of large volumes of data remain challenging,especially for two-dimensional or light materials because the diffraction signal recorded on the pixelated arrays is *** we employ data-driven manifold leaning approaches for straightforward visualization and exploration analysis of 4D-STEM datasets,distilling real-space neighboring effects on atomically resolved deflection patterns from single-layer graphene,with single dopant atoms,as recorded on a pixelated *** extracted patterns relate to both individual atom sites and sublattice structures,effectively discriminating single dopant anomalies via multimode *** believe manifold learning analysis will accelerate physics discoveries coupled between data-rich imaging mechanisms and materials such as ferroelectric,topological spin,and van der Waals heterostructures.

关键词： manifold straight details

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Continuous-wave terahertz diffraction tomography for measuring three-dimensional refractive index maps

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Chinese Optics Letters 2021年第12期19卷 150-155页

作者： Dayong Wang Xiaoyu Jin Jie Zhao Yunxin Wang Lu Rong john J.healy College of Physics and Optoelectronics Faculty of ScienceBeijing University of TechnologyBeijing 100124China Beijing Engineering Research Center of Precision Measurement Technology and Instruments Beijing 100124China Beijing-Dublin International College Beijing University of TechnologyBeijing 100124China

Three-dimensional(3D)refractive index(RI)distribution is important to reveal the object’s inner *** implemented terahertz(THz)diffraction tomography with a continuous-wave single-frequency THz source for measuring 3D RI *** off-axis holographic interference configuration was employed to obtain the quantitative scattered field of the object under each rotation *** 3D reconstruction algorithm adopted the filtered backpropagation method,which can theoretically calculate the exact scattering potential from the measured scattered *** on the Rytov approximation,the 3D RI distribution of polystyrene foam spheres was achieved with high fidelity,which verified the feasibility of the proposed method.

关键词： diffraction tomography three-dimensional terahertz imaging three-dimensional reconstruction algorithm refractive index measurement

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Continuous-wave terahertz in-line holographic diffraction tomography with the scattering fields reconstructed by a physics-enhanced deep neural network

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Photonics Research 2023年第12期11卷 2149-2158页

作者： XIAOYU JIN JIE ZHAO DAYONG WANG john Jhealy LU RONG YUNXIN WANG SHUFENG LIN College of Physics and Optoelectronics Faculty of ScienceBeijing University of TechnologyBeijing 100124China Beijing Engineering Research Center of Precision Measurement Technology and Instruments Beijing 100124China Beijing-Dublin International College Beijing University of TechnologyBeijing 100124China School of Electrical and Electronic Engineering College of Engineering and ArchitectureUniversity College DublinBelfieldDublin 4Ireland

Diffraction tomography is a promising,quantitative,and nondestructive three-dimensional(3D)imaging method that enables us to obtain the complex refractive index distribution of a *** acquisition of the scattered fields under the different illumination angles is a key issue,where the complex scattered fields need to be ***,in order to develop terahertz(THz)diffraction tomography,the advanced acquisition of the scattered fields is *** this paper,a THz in-line digital holographic diffraction tomography(THz-IDHDT)is proposed with an extremely compact optical configuration and implemented for the first time,to the best of our knowledge.A learning-based phase retrieval algorithm by combining the physical model and the convolution neural networks,named the physics-enhanced deep neural network(PhysenNet),is applied to reconstruct the THz in-line digital hologram,and obtain the complex amplitude distribution of the sample with high *** advantages of the PhysenNet are that there is no need for pretraining by using a large set of labeled data,and it can also work for thick *** with a continuous-wave THz laser,the PhysenNet is first demonstrated by using the thin samples and exhibits superiority in terms of imaging *** importantly,with regard to the thick samples,PhysenNet still works well,and can offer 2D complex scattered fields for diffraction ***,the 3D refractive index maps of two types of foam sphere samples are successfully reconstructed by the proposed *** a single foam sphere,the relative error of the average refractive index value is only 0.17%,compared to the commercial THz time-domain spectroscopy *** demonstrates the feasibility and high accuracy of the THz-IDHDT,and the idea can be applied to other wavebands as well.

关键词： holographic scattered wave

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Author Correction:Manifold learning of four-dimensional scanning transmission electron microscopy

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npj Computational Materials 2020年第1期6卷 1073-1073页

作者： Xin Li Ondrej E.Dyck Mark P.Oxley Andrew R.Lupini Leland McInnes john healy Stephen Jesse Sergei V.Kalinin Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge USA Institute for Functional Imaging of Materials Oak Ridge National Laboratory Oak Ridge USA Tutte Institute for Mathematics and Computing Ottawa Canada

The original version of the published Article had a mistake in the Acknowledgements *** Acknowledgments have been updated to the following:This research was supported by the US Department of Energy,Basic Energy Sciences,Materials Sciences and Engineering Division(M.P.O.,A.R.L.,S.V.K.)and conducted at the Center for Nanophase Materials Sciences,which is a US DOE Office of Science User Facility(X.L.,O.E.D.,S.J.).*** *** support from Tutte Institute for Mathematics and Computing,Canada.

关键词： section ledgment Manifold

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Effect of institutional volume on laparoscopic cholecystectomy outcomes: Systematic review and metaanalysis

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World Journal of Meta-Analysis 2015年第1期3卷 26-35页

作者： Muireann Murray Donagh A healy john Ferguson Khalid Bashar Seamus McHugh Mary Clarke Moloney Stewart R Walsh Department of Surgery University Hospital Limerick Department of Nephrology Graduate Entry Medical School University of Limerick Health Research Institute University of Limerick Department of Surgery University College Hospital

AIM: To determine whether institutional laparoscopy cholecystectomy(LC) volume affects rates of mortality, conversion to open surgery, bile leakage and bile duct injury(BDI).METHODS: Eligible studies were prospective or retrospective cohort studies that provided data on outcomes from consecutive LC procedures in single institutions. Relevant outcomes were mortality, conversion to open surgery, bile leakage and BDI. We performed a Medline search and extracted data. A regression analysis using generalized estimating equations were used to determine the influence of annual institutional LC caseload on outcomes. A sensitivity analysis was performed including only those studies that were published after ***: Seventy-three cohorts(127404 LC procedures) were included. Average complication rates were 0.06% for mortality, 3.23% for conversion, 0.44% for bile leakage and 0.28% for bile duct injury. Annual institutional caseload did not influence rates of mortality(P = 0.142), bile leakage(P = 0.111) or bile duct injury(P = 0.198) although increasing caseload was associated with reduced incidence of conversion(P = 0.019). Results from the sensitivity analyses were ***: Institutional volume is a determinant of LC complications. It is unclear whether volume is directly linked to complication rates or whether it is an index for protocolised care.

关键词： Abdominal Cholecystectomy Quality control Systematic review Meta-analysis

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Real-time Measurements of Secondary Organic Aerosol from the Photooxidation of Naphthalene using Single Particle Mass Spectrometry

Real-time Measurements of Secondary Organic Aerosol from the...

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十一届全国气溶胶会议暨第十届海峡两岸气溶胶技术研讨会

作者： ang Chen Robert M.healy Shouming Zhou john C.Weng Yer Insitute of Earth Environment Chinese Academy of Sciences Department of Chemistry and Environmental Research Institute University College Cork

Naphthalene is the most abundant polycyclic aromatic hydrocarbon detected in urban air and has recently been identified as an important precursor for the formation of secondary organic aerosol（SOA） in the atmosphere. In this work, a series of simulation chamber experiments has been performed on the photooxidation of naphthalene under a variety of reaction conditions. The decay of naphthalene was monitored using in situ FTIR spectroscopy and the formation and evolution of SOA was followed using a scanning mobility particle sizer. An Aerosol Time-of-Flight Mass Spectrometer（ATOFMS） was used to determine the chemical composition of the SOA in real-time. In experiments using NOx as the hydroxyl radical precursor, the single particle mass spectra were found to change slowly over a period of hours. The positive ion mass spectra initially contained hydrocarbon fragments typical of aromatic species which are tentatively attributed to ring-retaining oxidation products such as naphthol and nitronaphthalene. After 3-4 hours the intensity of the hydrocarbon fragments was significantly reduced and the negative ion mass spectra displayed characteristic features of oxidized organic aerosol and nitrates. Interestingly, some of these peaks continued to increase after the lights were turned off, suggesting that particle phase processing was maintained, even under dark conditions. The results from these experiments indicate that ATOFMS can be used to monitor chemical changes in SOA in real-time and is a potentially useful tool for investigating aerosol formation and ageing.

关键词： Secondary Organic Aerosol Naphthalene online single particle mass spectrometer

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