检索结果-南通市图书馆

Scanning Raman Picoscopy: Angstrom-Resolved Tip-Enhanced Raman Spectromicroscopy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2021年第1期34卷 1-14,I0011页

作者： Yao Zhang Yang Zhang zhen-chao dong Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics Department of Chemical PhysicsUniversity of Science and Technology of ChinaHefei 230026China

In this review,we present a brief overview on the recent advances in Angstr6m-resolved tip-enhanced Raman *** first introduce the theoretical understanding of the confinement of light at the atomistic scale,and explain how the Raman scattering from a single molecule happens under the“illumination”of such an atomically confined *** we describe the latest developments on Angstr6m-resolved tipenhanced Raman spectromicroscopy,particularly on a new methodology called“scanning Raman picoscopy”for visually cons true ting the chemical st ruc ture of a single molecule in real ***,we give a perspective of this technique in various applications where iden ti fying the chemical st ruc tu res of mat erials at the chemical bond level is required.

关键词： Scanning Raman picoscopy Tip-enhanced Raman spectroscopy Structural determination Picocavity plasmon Angstr6m resolution

Dispersion and STM Characterization of Au-CdSe Nanohybrids on Au（111）

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2012年第2期25卷 231-234,I0004页

作者： Bo Gao Yan-min Kuang Yuan Liao zhen-chao dong Hefei National laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230025China

We report the dispersion and scanning tunneling microscopy （STM） characterization of iso- lated Au-CdSe nanohybrids on atomically fiat Au（111） through surface modifications. The top terminal groups of spacer molecules self-assembled on the surface are found critical for locking the nanohybrids into a well-separated state. The STM results indicate that both thiol and carboxylic terminals are effective in this aspect by making strong interaction with the Au portions of the nanohybrids. An argon ion sputtering technique is also proposed to clean up organic contaminants on the surface for improved STM imaging of individual Au-CdSe nanohybrids. These observations help to enrich technical approaches to dispersing individual nanostructures on the surface and provide opportunities to explore their local electroluminescent and energy transfer properties at the nanoscale.

关键词： Metal-semiconductor nanostructure Nanoparticle dispersion Sputter cleaning Scanning tunneling microscopy Plasmon-exciton coupling

Role of Nanocavity Plasmons in Tunneling Electron Induced Light Emission on and near a Molecule

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2018年第3期31卷 263-268,367页

作者： Hui-fang Wang Gong Chen Xiao-guang Li zhen-chao dong Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Tech-nology of ChinaHefei 230026China School of Physics and Engineering Zhengzhou UniversityZhengzhou 450052China Institute for Advanced Study Shenzhen UniversityShenzhen 518060China

By using a microscopic quantum model, we study theoretically different roles of nanocavity plasmons in scanning tunneling microscope(STM) induced light emission upon selective initial excitation of molecules or plasmons. The time evolution and spectroscopic properties of the emission from the coupled plasmon-molecule system in each case are studied using time-dependent quantum mater equations. When the STM tip is placed on the molecule to ensure direct carrier injection induced molecular excitation, the major role of the plasmons is to enhance the molecular emission via increasing its radiative decay rate, resulting in sharp molecule-specific emission peaks. On the other hand, when the STM tip is located in close proximity to the edge of the molecule but without direct carrier injection into the molecule, the role of the plasmon-molecule coupling is to cause destructive interferences between the two quantum objects, leading to the occurrence of Fano dips around the energy of the molecular exciton in the plasmonic emission spectra.

关键词： Scanning tunneling microscope induced luminescence Plasmon enhanced spec-troscopy Fano resonance Quantum master equation

Visually constructing the chemical structure of a single molecule by scanning Raman picoscopy

在线全文

学校读者我要写书评

暂无评论

National Science Review 2019年第6期6卷 1169-1175页

作者： Yao Zhang Ben Yang Atif Ghafoor Yang Zhang Yu-Fan Zhang Rui-Pu Wang Jin-Long Yang Yi Luo zhen-chao dong J.G.Hou Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China

The strong spatial confinement of a nanocavity plasmonic field has made it possible to visualize the inner structure of a single molecule and even to distinguish its vibrational modes in real space. With such ever-improved spatial resolution, it is anticipated that full vibrational imaging of a molecule could be achieved to reveal molecular structural details. Here we demonstrate full Raman images of individual vibrational modes at the ■ level for a single Mg-porphine molecule, revealing distinct characteristics of each vibrational mode in real space. Furthermore, by exploiting the underlying interference effect and Raman fingerprint database, we propose a new methodology for structural determination, which we have called 'scanning Raman picoscopy', to show how such ultrahigh-resolution spectromicroscopic vibrational images can be used to visually assemble the chemical structure of a single molecule through a simple Lego-like building process.

关键词： scanning Raman picoscopy tip-enhanced Raman spectroscopy structure determination vibrational mode imaging interference effect

Fusion of Spiral Convolution-LSTM for Intrusion Detection Modeling

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第5期79卷 2315-2329页

作者： Fei Wang zhen dong School of Cyberspace Security Gansu University of Political Science and LawLanzhou73000China

Aiming at the problems of low accuracy and slow convergence speed of current intrusion detection models,SpiralConvolution is combined with Long Short-Term Memory Network to construct a new intrusion detection *** dataset is first preprocessed using solo thermal encoding and normalization *** the spiral convolution-Long Short-Term Memory Network model is constructed,which consists of spiral convolution,a two-layer long short-term memory network,and a *** is shown through experiments that the model is characterized by high accuracy,small model computation,and fast convergence speed relative to previous deep learning *** model uses a new neural network to achieve fast and accurate network traffic intrusion *** model in this paper achieves 0.9706 and 0.8432 accuracy rates on the NSL-KDD dataset and the UNSWNB-15 dataset under five classifications and ten classes,respectively.

关键词： Intrusion detection deep learning spiral convolution long and short term memory networks 1D-spiral convolution

Dielectric Constant Calculation of Poly(vinylidene fluoride)Based on Finite Field and Density Functional Theory

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第5期42卷 655-662,I0009页

作者： Yong-Zhi Lin Lu-Kun Feng Ya-dong Li chao-Fan Chang Cai-zhen Zhu Ming-Liang Wang Jian Xu College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen518055China Chengdu Institute of Organic Chemistry Chinese Academy of SciencesChengdu610041China

In this study,we proposed a novel method that integrates density functional theory(DFT)with the finite field method to accurately estimate the polarizability and dielectric constant of *** approach effectively accounts for the influence of electronic and geometric conformation changed on the dielectric *** validated our method using polyethylene(PE)and polytetrafluoroethylene(PTFE)as benchmark materials,and found that it reliably predicted their dielectric ***,we explored the impact of conformation variations in poly(vinylidene fluoride)(PVDF)on its dielectric constant and *** resulting dielectric constants ofα-andγ-PVDF(3.0)showed excellent agreement with crystalline PVDF in *** findings illuminate the relationship between PVDF’s structural properties and its electrical behavior,offering valuable insights for material design and applications.

关键词： Dielectric constant PVDF Finite field DFT

Preoperatively predicting vessels encapsulating tumor clusters in hepatocellular carcinoma:Machine learning model based on contrast-enhanced computed tomography

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Oncology 2024年第3期16卷 857-874页

作者： chao Zhang Hai Zhong Fang Zhao zhen-Yu Ma zheng-Jun Dai Guo-dong Pang Department of Radiology The Second Hospital of Shandong UniversityJinan 250033Shandong ProvinceChina Department of Radiology Qilu Hospital of Shandong UniversityJinan 250014Shandong ProvinceChina Department of Radiology Linglong Yingcheng HospitalYantai 265499Shandong ProvinceChina Department of Scientific Research Huiying Medical Technology Co.LtdBeijing 100192China

BACKGROUND Recently,vessels encapsulating tumor clusters(VETC)was considered as a distinct pattern of tumor vascularization which can primarily facilitate the entry of the whole tumor cluster into the bloodstream in an invasion independent manner,and was regarded as an independent risk factor for poor prognosis in hepatocellular carcinoma(HCC).AIM To develop and validate a preoperative nomogram using contrast-enhanced computed tomography(CECT)to predict the presence of VETC+in *** We retrospectively evaluated 190 patients with pathologically confirmed HCC who underwent CECT scanning and immunochemical staining for cluster of differentiation 34 at two medical *** analysis was conducted on intratumoral and peritumoral regions in the portal vein *** features,essential for identifying VETC+HCC,were extracted and utilized to develop a radiomics model using machine learning algorithms in the training *** model’s performance was validated on two separate test *** operating characteristic(ROC)analysis was employed to compare the identified performance of three models in predicting the VETC status of HCC on both training and test *** most predictive model was then used to constructed a radiomics nomogram that integrated the independent clinical-radiological *** and decision curve analysis were used to assess the performance characteristics of the clinical-radiological features,the radiomics features and the radiomics *** The study included 190 individuals from two independent centers,with the majority being male(81%)and a median age of 57 years(interquartile range:51-66).The area under the curve(AUC)for the combined radiomics features selected from the intratumoral and peritumoral areas were 0.825,0.788,and 0.680 in the training set and the two test sets.A total of 13 features were selected to construct the *** nomogram,combining clinicalradiological and combined radiomics features could acc

关键词： Hepatocellular carcinoma Vessels encapsulating tumor clusters Intratumoral and peritumoral regions Radiomics features Nomog

Evaluation of Auto-Ignition Characteristics of Diesel Surrogate Fuels with the Same Derived Cetane Numbers at Changed Thermodynamic Environments

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第4期33卷 1590-1606页

作者： ZHANG Cong GUAN Yuanhang HUANG zhen HAN dong Key Laboratory for Power Machinery and Engineering Ministry of EducationShanghai Jiao Tong UniversityShanghai200240China College of Smart Energy Shanghai Jiao Tong UniversityShanghai200240China Shanghai Non-carbon Energy Conversion and Utilization Institute Shanghai200240China

The ignition tendency of diesel fuels is highly sensitive to ambient conditions and fuel *** this study,the ignition characteristics of different diesel surrogate fuels with the same derived cetane numbers(DCN)were measured and compared in varied thermodynamic and oxidizing *** combustion pressures,heat release rates,ignition delays,and combustion delays of the test fuels were *** experimental results showed that the diesel surrogate fuels with the same DCNs exhibit similar ignition propensity at standard DCN test ***,for the test conditions of high cetane fuels,high ambient temperatures,and suficient oxygen concentrations,surrogate fuels with the same DCN have similar ignition behaviors,and using the DCN to evaluate fuel ignition tendency is ***,for the test conditions of low cetane fuels,low ambient temperatures,and reduced oxygen concentrations,different ignition behaviors are observed for the surrogate fuels with the same DCN,so at these conditions using DCN as the evaluation index for fuel ignition tendency may lead to higher uncertainty.

关键词： diesel fuels surrogate fuels derived cetane numbers constant volume combustion chamber

Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第2期23卷 445-454页

作者： Li Yuchun Shen chao Liu Wei Li dong Department of Hydraulic Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this *** auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on *** parametric vibration equation is established for the test model using the finite-element *** auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent *** effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test *** with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental *** a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric *** with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

关键词： auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd Bridge