期刊文献+
共找到56,178篇文章
< 1 2 250 >
每页显示 20 50 100
Unveiling nano-scale chemical inhomogeneity in surface oxide films formed on V-and N-containing martensite stainless steel by synchrotron X-ray photoelectron emission spectroscopy/microscopy and microscopic X-ray absorption spectroscopy
1
作者 Xiaoqi Yue Dihao Chen +11 位作者 Anantha Krishnan Isac Lazar Yuran Niu Evangelos Golias Carsten Wiemann Andrei Gloskovskii Christoph Schlueter Arno Jeromin Thomas F.Keller Haijie Tong Sebastian Ejnermark Jinshan Pan 《Journal of Materials Science & Technology》 2025年第2期191-203,共13页
Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ra... Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ray Photoelectron emission spectroscopy(HAXPES)and microscopy(HAXPEEM)as well as microscopic X-ray absorption spectroscopy(μ-XAS)techniques.The results reveal the inhomogeneity in the oxide films on the micron-sized Cr_(2)N-and VN-type particles,while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600℃.The oxide film formed on Cr_(2)N-type particles is rich in Cr_(2)O_(3) compared with that on the martensite matrix and VN-type particles.With the increase of tempering temperature,Cr_(2)O_(3) formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles. 展开更多
关键词 Synchrotron X-ray photoelectron emission microscopy Hard X-ray photoelectron emission spectroscopy Synchrotron microscopic X-ray absorption spectroscopy Martensite stainless steel Surface oxide film
原文传递
Electron Microscopy and Spectroscopy Investigation of Atomic, Electronic, and Phonon Structures of NdNiO_(2)/SrTiO_(3) Interface
2
作者 Yuan Yin Mei Wu +9 位作者 Xiang Ding Peiyi He Qize Li Xiaowen Zhang Ruixue Zhu Ruilin Mao Xiaoyue Gao Ruochen Shi Liang Qiao Peng Gao 《Chinese Physics Letters》 2025年第4期130-141,共12页
The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclus... The infinite-layer nickelates,proposed as analogs to superconducting cuprates,provide a promising platform for exploring the mechanisms of unconventional superconductivity.However,the superconductivity has been exclusively observed in thin films under atmospheric pressure,underscoring the critical role of the heterointerface. 展开更多
关键词 atomic structure phonon structure electron microscopy electronic structure spectroscopy NdNiO SrTiO interface thin films superconducting cupratesprovide
原文传递
Influence of Radio-Frequency Voltage on Electron Spin Resonance Spectroscopy in Scanning Tunneling Microscopy
3
作者 Jiaan Cao Lyuzhou Ye +1 位作者 Rui-Xue Xu Xiao Zheng 《Chinese Journal of Chemical Physics》 2025年第4期375-381,I0104,共8页
Over the last decade,the integra-tion of scanning tunneling mi-croscopy(STM)and electron spin resonance(ESR)spectroscopy has emerged as a powerful tool for measuring spin states of surface-adsorbed molecules.The radio... Over the last decade,the integra-tion of scanning tunneling mi-croscopy(STM)and electron spin resonance(ESR)spectroscopy has emerged as a powerful tool for measuring spin states of surface-adsorbed molecules.The radio-fre-quency voltage is a key physical quantity that influences STM-ESR spectra.However,the specific effect of radio-frequency voltage on the real-time electric current associated with STM-ESR sig-nal remains unclear.In this work,we employ the hierarchical equations of motion method to simulate the STM-ESR spectra of a single spin-1/2 surface-adsorbed molecule and track the temporal evolution of the electric current,thereby elucidating how the radio-frequency volt-age influences the features of STM-ESR spectra,the real-time electric current,and the char-acteristic frequencies conveyed by the electric current.These theoretical insights facilitate a deeper comprehension of experimental phenomena. 展开更多
关键词 Electron spin resonance Scanning tunneling microscopy Radio-frequency volt-age Real-time electric current
在线阅读 下载PDF
Microscopic and spectroscopic analysis of atmospheric iron-containing single particles in Lhasa,Xizang
4
作者 Junyu Chen Daobin Zhang +6 位作者 Yiran Fu Jinhu Wang Xiaomei Cui Ci-ren Qu-zong Qiangying Zhang Chan Jin Bu Duo 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2024年第7期40-50,共11页
The Tibetan Plateau,known as the“Third Pole”,is currently in a state of perturbation caused by intensified human activity.In this study,56 samples were obtained at the five sampling sites in typical area of Lhasa ci... The Tibetan Plateau,known as the“Third Pole”,is currently in a state of perturbation caused by intensified human activity.In this study,56 samples were obtained at the five sampling sites in typical area of Lhasa city and their physical and chemical properties were investigated by TEM/EDS,STXM,and NEXAFS spectroscopy.After careful examination of 3387single particles,the results showed that Fe should be one of the most frequent metal elements.The Fe-containing single particles in irregular shape and micrometer size was about7.8%and might be mainly from local sources.Meanwhile,the Fe was located on the subsurface of single particles and might be existed in the form of iron oxide.Interestingly,the core-shell structure of iron-containing particles were about 38.8%and might be present as single-,dual-or triple-core shell structure and multi-core shell structure with the Fe/Si ratios of 17.5,10.5,2.9 and 1.2,respectively.Meanwhile,iron and manganese were found to coexist with identical distributions in the single particles,which might induce a synergistic effect between iron and manganese in catalytic oxidation.Finally,the solid spherical structure of Fe-containing particles without an external layer were about 53.4%.The elements of Fe and Mn were co-existed,and might be presented as iron oxide-manganese oxide-silica composite.Moreover,the ferrous and ferric forms of iron might be co-existed.Such information can be valuable in expanding our understanding of Fe-containing particles in the Tibetan Plateau atmosphere. 展开更多
关键词 Fe-containing single particle Irregular shape Core-shell structure Solid spherical structure Transmission electron microscopy Synchrotron X-ray microscopy
原文传递
Characteristics and differential diagnosis of common verrucous proliferative skin diseases under dermoscopy and reflectance confocal microscopy 被引量:1
5
作者 ZHOU Lu FU Yule +7 位作者 HUANG Jian TANG Zhen LU Jianyun TAN Lina WANG Dan ZENG Jinrong WANG Jia GAO Lihua 《中南大学学报(医学版)》 北大核心 2025年第3期358-365,共8页
Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often ... Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often posing diagnostic challenges.Dermoscopy and reflectance confocal microscopy(RCM)can aid in their differentiation,yet their specific features under these tools have not been systematically described.This study aims to summarize and analyze the dermoscopic and RCM features of VEN,SK,VP,VV,and NS.Methods:A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled.Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions.Results:Under dermoscopy,the 5 diseases displayed distinct characteristics:VEN typically showed gyriform structures;SK was characterized by gyriform structures,comedo-like openings,and milia-like cysts;VP and VV featured dotted vessels and frogspawn-like structures;NS presented as brownish-yellow globules.RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases.Specific features included gyriform structures and elongated rete ridges in VEN;pseudocysts and gyriform structures in SK;evenly distributed ring-like structures in VP;vacuolated cells and papillomatous proliferation in VV;and frogspawn-like structures in NS.Conclusion:These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM.The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases. 展开更多
关键词 reflectance confocal microscopy DERMOSCOPY verrucous proliferation verrucous epidermal nevus seborrheic keratosis verruca plana verruca vulgaris nevus sebaceous
暂未订购
Fast full-color pathological imaging using Fourier ptychographic microscopy via closed-form model-based colorization 被引量:2
6
作者 Yanqi Chen Jiurun Chen +4 位作者 Zhiping Wang Yuting Gao Yonghong He Yishi Shi An Pan 《Advanced Photonics Nexus》 2025年第2期7-16,共10页
Full-color imaging is essential in digital pathology for accurate tissue analysis.Utilizing advanced optical modulation and phase retrieval algorithms,Fourier ptychographic microscopy(FPM)offers a powerful solution fo... Full-color imaging is essential in digital pathology for accurate tissue analysis.Utilizing advanced optical modulation and phase retrieval algorithms,Fourier ptychographic microscopy(FPM)offers a powerful solution for high-throughput digital pathology,combining high resolution,large field of view,and extended depth of field(DOF).However,the full-color capabilities of FPM are hindered by coherent color artifacts and reduced computational efficiency,which significantly limits its practical applications.Color-transferbased FPM(CFPM)has emerged as a potential solution,theoretically reducing both acquisition and reconstruction threefold time.Yet,existing methods fall short of achieving the desired reconstruction speed and colorization quality.In this study,we report a generalized dual-color-space constrained model for FPM colorization.This model provides a mathematical framework for model-based FPM colorization,enabling a closed-form solution without the need for redundant iterative calculations.Our approach,termed generalized CFPM(gCFPM),achieves colorization within seconds for megapixel-scale images,delivering superior colorization quality in terms of both colorfulness and sharpness,along with an extended DOF.Both simulations and experiments demonstrate that gCFPM surpasses state-of-the-art methods across all evaluated criteria.Our work offers a robust and comprehensive workflow for high-throughput full-color pathological imaging using FPM platforms,laying a solid foundation for future advancements in methodology and engineering. 展开更多
关键词 Fourier ptychographic microscopy color transfer dual-color-space constrained model
在线阅读 下载PDF
Highly sensitive laser spectroscopy sensing based on a novel four-prong quartz tuning fork 被引量:1
7
作者 Runqiu Wang Shunda Qiao +1 位作者 Ying He Yufei Ma 《Opto-Electronic Advances》 2025年第4期6-16,共11页
In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical sim... In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical simulation model was established to optimize the design of the QTF structure.In the simulation of quartz-enhanced photoacoustic spectroscopy(QEPAS)technology,the maximum stress and the surface charge density of the four-prong QTF demonstrated increases of 11.1-fold and 15.9-fold,respectively,compared to that of the standard two-prong QTF.In the simulation of light-induced thermoelastic spectroscopy(LITES)technology,the surface temperature difference of the four-prong QTF was found to be 11.4 times greater than that of the standard QTF.Experimental results indicated that the C_(2)H_(2)-QEPAS system based on this innovative design improved the signal-to-noise-ratio(SNR)by 4.67 times compared with the standard QTF-based system,and the SNR could increase up to 147.72 times when the four-prong QTF was equipped with its optimal acoustic micro-resonator(AmR).When the average time of the system reached 370 s,the system achieved a MDL as low as 21 ppb.The four-prong QTF-based C_(2)H_(2)-LITES system exhibited a SNR improvement by a factor of 4.52,and a MDL of 96 ppb was obtained when the average time of the system reached 100 s.The theoretical and experimental results effectively demonstrated the superiority of the four-prong QTF in the field of laser spectroscopy sensing. 展开更多
关键词 four-prong quartz tuning fork C2H2 detection quartz-enhanced photoacoustic spectroscopy light-induced thermoelastic spectroscopy
在线阅读 下载PDF
In-situ observation of nonmetallic inclusions in steel using confocal scanning laser microscopy:A review 被引量:1
8
作者 Ying Ren Lifeng Zhang 《International Journal of Minerals,Metallurgy and Materials》 2025年第5期975-991,共17页
The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are revi... The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are reviewed and summarized,particularly the col-lision of various inclusions,dissolution of inclusions in liquid slag,and reactions between inclusions and steel.Solid inclusions exhibited a high collision tendency,whereas pure liquid inclusions exhibited minimal collisions because of the small attraction force induced by their<90°contact angle with molten steel.The collision of complex inclusions in molten steel was not included in the scope of this study and should be evaluated in future studies.Higher CaO/Al_(2)O_(3)and CaO/SiO_(2)ratios in liquid slag promoted the dissolution of Al_(2)O_(3)-based in-clusions.The formation of solid phases in the slag should be prevented to improve dissolution of inclusions.To accurately simulate the dissolution of inclusions in liquid slag,in-situ observation of the dissolution of inclusions at the steel-slag interface is necessary.Using a combination of CSLM and scanning electron microscopy-energy dispersive spectroscopy,the composition and morphological evolution of the inclusions during their modification by the dissolved elements in steel were observed and analyzed.Although the in-situ observa-tion of MnS and TiN precipitations has been widely studied,the in-situ observation of the evolution of oxide inclusions in steel during so-lidification and heating processes has rarely been reported.The effects of temperature,heating and cooling rates,and inclusion character-istics on the formation of acicular ferrites(AFs)have been widely studied.At a cooling rate of 3-5 K/s,the order of AF growth rate in-duced by different inclusions,as reported in literature,is Ti-O<Ti-Ca-Zr-Al-O<Mg-O<Ti-Zr-Al-O<Mn-Ti-Al-O<Ti-Al-O<Zr-Ti-Al-O.Further comprehensive experiments are required to investigate the quantitative relationship between the formation of AFs and inclusions. 展开更多
关键词 INCLUSION STEEL in-situ observation confocal scanning laser microscopy
在线阅读 下载PDF
Value of Magnetic Resonance Spectroscopy for Examining Fetal Brain Development in Mid-to Late Pregnancy 被引量:1
9
作者 Dejuan Shan Yi Zhang +3 位作者 Maobo Wang Yanyan Liu Yudong Wang Lianxiang Xiao 《iRADIOLOGY》 2025年第3期209-213,共5页
Background:Magnetic resonance spectroscopy(MRS)represents a significant advancement in the noninvasive assessment of brain metabolism.MRS can provide valuable metabolic information and facilitate more accurate diagnos... Background:Magnetic resonance spectroscopy(MRS)represents a significant advancement in the noninvasive assessment of brain metabolism.MRS can provide valuable metabolic information and facilitate more accurate diagnoses of intrauterine fetal brain development than was previously possible.To obtain information regarding normal intrauterine fetal brain metabolism and to establish gestational age-specific reference values for normal fetal brain metabolites for subsequent use in MRS,we conducted MRS scans of normal fetal brains during mid-to late-term pregnancies,along with related processing.Methods:In this prospective study,MRS scans were conducted on 109 fetuses,with a total of 54 normal fetal brains enrolled on the basis of specific inclusion and exclusion criteria.We analyzed metabolic ratios,including the sum of N-acetylaspartate(NAA)and total N-acetylaspartate(tNAA),total choline(tCho),inositol(Ins),and total creatine(tCr),in relation to gestational age.Results:Gestational age was significantly correlated with specific metabolic ratios(Ins/tCr:r=-0.75,p<0.0001;tCho/tCr:r=-0.50,p<0.0001),especially tNAA/tCho(tNAA/tCho:r=0.54,p<0.0001)and tNAA/Ins(r=0.56,p<0.0001),providing a baseline for fetal brain metabolic assessment.Linear regression analysis was used to calculate regression lines for fetal brain metabolite ratios.Slopes were tested at p of 0.05.Conclusions:The current findings confirmed a significant correlation between fetal brain metabolites and gestational age,supporting the feasibility of establishing standard values for these metabolites in fetal brain assessment. 展开更多
关键词 CHOLINE CREATINE fetal brain metabolism magnetic resonance spectroscopy N-ACETYLASPARTATE
暂未订购
Development and Application of Cavity-based Absorption Spectroscopy in Atmospheric Chemistry:Recent Progress 被引量:1
10
作者 Weixiong ZHAO Nana YANG +6 位作者 Renzhi HU Bo FANG Jiacheng ZHOU Chuan LIN Feihu CHENG Pinhua XIE Weijun ZHANG 《Advances in Atmospheric Sciences》 2025年第4期605-622,共18页
Atmospheric chemistry research and atmospheric measurement techniques have mutually promoted each other and developed rapidly in China in recent years.Cavity-based absorption spectroscopy,which uses a high-finesse cav... Atmospheric chemistry research and atmospheric measurement techniques have mutually promoted each other and developed rapidly in China in recent years.Cavity-based absorption spectroscopy,which uses a high-finesse cavity to achieve very long absorption path-length,thereby achieving ultra-high detection sensitivity,plays an extremely important role in atmospheric chemistry research.Based on the Beer–Lambert law,this technology has the unique advantages of being non-destructive,chemical-free,and highly selective.It does not require any sample preparation and can quantitatively analyze atmospheric trace gases in real time and in situ.In this paper,we review the following:(1)key technological advances in different cavity-based absorption spectroscopy techniques,including cavity ring-down spectroscopy,cavityenhanced absorption spectroscopy,cavity attenuated phase shift spectroscopy,and their extensions;and(2)applications of these techniques in the detection of atmospheric reactive species,such as total peroxy radical,formaldehyde,and reactive nitrogen(e.g.,NOx,HONO,peroxy nitrates,and alkyl nitrates).The review systematically introduces cavity-based absorption spectroscopy techniques and their applications in atmospheric chemistry,which will help promote further communication and cooperation in the fields of laser spectroscopy and atmospheric chemistry. 展开更多
关键词 cavity-based absorption spectroscopy atmospheric chemistry atmospheric reactive species
在线阅读 下载PDF
Coulomb attraction driven spontaneous molecule-hotspot pairing enables universal,fast,and large-scale uniform single-molecule Raman spectroscopy 被引量:1
11
作者 Lihong Hong Haiyao Yang +2 位作者 Jianzhi Zhang Zihan Gao Zhi-Yuan Li 《Opto-Electronic Advances》 2025年第7期37-49,共13页
Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrate... Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrates.Here we present a SM-SERS scheme that involves simultaneously giant chemical enhancement from WS22D materials,giant electromagnetic enhancement from plasmonic nanogap hot spot,and inhibition of molecular fluorescence influence under near-infrared laser illumination.Remarkably we find Coulomb attraction between analyte and gold nanoparticle can trigger spontaneous formation of molecule-hotspot pairing with high precision,stability and robustness.The scheme has enabled realization of universal,robust,fast,and large-scale uniform SM-SERS detection for three Raman molecules of rhodamine B,rhodamine 6G,and crystal violet with a very low detection limit of 10−16 M and at a very fast spectrum acquisition time of 50 ms. 展开更多
关键词 single-molecule Raman spectroscopy Coulomb attractions electromagnetic enhancement chemical enhancement near-infrared laser illumination
在线阅读 下载PDF
Combining machine learning algorithms with traditional methods for resolving the atomic-scale dynamic structure of monolayer MoS_(2) in high-resolution transmission electron microscopy 被引量:1
12
作者 Yu Meng Shuya Wang +5 位作者 Xibiao Ren Han Xue Xuejun Yue Chuanhong Jin Shanggang Lin Fang Lin 《Chinese Physics B》 2025年第1期162-170,共9页
High-resolution transmission electron microscopy(HRTEM)promises rapid atomic-scale dynamic structure imaging.Yet,the precision limitations of aberration parameters and the challenge of eliminating aberrations in Cs-co... High-resolution transmission electron microscopy(HRTEM)promises rapid atomic-scale dynamic structure imaging.Yet,the precision limitations of aberration parameters and the challenge of eliminating aberrations in Cs-corrected transmission electron microscopy constrain resolution.A machine learning algorithm is developed to determine the aberration parameters with higher precision from small,lattice-periodic crystal images.The proposed algorithm is then validated with simulated HRTEM images of graphene and applied to the experimental images of a molybdenum disulfide(MoS_(2))monolayer with 25 variables(14 aberrations)resolved in wide ranges.Using these measured parameters,the phases of the exit-wave functions are reconstructed for each image in a focal series of MoS_(2)monolayers.The images were acquired due to the unexpected movement of the specimen holder.Four-dimensional data extraction reveals time-varying atomic structures and ripple.In particular,the atomic evolution of the sulfur-vacancy point and line defects,as well as the edge structure near the amorphous,is visualized as the resolution has been improved from about 1.75?to 0.9 A.This method can help salvage important transmission electron microscope images and is beneficial for the images obtained from electron microscopes with average stability. 展开更多
关键词 aberration measurement high-resolution transmission electron microscopy feature-extraction networks exit-wave reconstruction monolayer MoS_(2)
原文传递
Development and prospect of near-infrared spectroscopy-assisted schizophrenia diagnosis based on bibliometrics
13
作者 Yan Zhang Hao-Yu Xing Juan Yan 《World Journal of Psychiatry》 SCIE 2025年第1期7-11,共5页
In this editorial,we comment on the recent article by Fei et al exploring the field of near-infrared spectroscopy(NIRS)research in schizophrenia from a bibliometrics perspective.In recent years,NIRS has shown unique a... In this editorial,we comment on the recent article by Fei et al exploring the field of near-infrared spectroscopy(NIRS)research in schizophrenia from a bibliometrics perspective.In recent years,NIRS has shown unique advantages in the auxiliary diagnosis of schizophrenia,and the introduction of bibliometrics has provided a macro perspective for research in this field.Despite the opportunities brought about by these technological developments,remaining challenges require multidi-sciplinary approach to devise a reliable and accurate diagnosis system for schizo-phrenia.Nonetheless,NIRS-assisted technology is expected to contribute to the division of methods for early intervention and treatment of schizophrenia. 展开更多
关键词 BIBLIOMETRICS SCHIZOPHRENIA Near-infrared spectroscopy Diagnostic technique Data analysis
暂未订购
A promising approach for quantifying focal stroke modeling and assessing stroke progression:optical resolution photoacoustic microscopy photothrombosis
14
作者 Xiao Liang Xingping Quan +6 位作者 Xiaorui Geng Yujing Huang Yonghua Zhao Lei Xi Zhen Yuan Ping Wang Bin Liu 《Neural Regeneration Research》 SCIE CAS 2025年第7期2029-2037,共9页
To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these me... To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes. 展开更多
关键词 AGE-DEPENDENT cerebral cortex ischemic stroke mouse model optical coherence tomography angiography photoacoustic microscopy PHOTOTHROMBOSIS vascular imaging
暂未订购
Illuminating the microscopic mysteries of enamel demineralization through terahertz near-field imaging
15
作者 XIAO Feng ZHANG Xiao-Qiu-Yan +6 位作者 CHENG Li XU Xing-Xing ZHANG Tian-Yu TANG Fu HU Tao HU Min LIU Sheng-Gang 《红外与毫米波学报》 北大核心 2025年第5期720-725,共6页
Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especial... Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especially continuous wave(CW)THz near-field scanning microscopy(THz-SNOM)with its nanoscale reso⁃lution,can be promising in biomedical imaging.In addition,compared with traditional THz time-domain spec⁃troscopy(TDS),portable solid-state source as the emission has higher power and SNR,lower cost,and can ob⁃tain more precise imaging.In this study,we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale.We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens,mainly due to the decrease in permittivity.This new approach offers valuable insights into the micro⁃scopic processes of enamel demineralization,laying the foundation for further research and treatment. 展开更多
关键词 demineralized enamel near-field scanning microscopy continuous wave TERAHERTZ
在线阅读 下载PDF
Infrared spectroscopic analysis of O-H bond dynamics in one-dimensional confined water and bulk water
16
作者 ZHANG Lei WANG Tian-Qi FAN Yan-Ping 《红外与毫米波学报》 北大核心 2025年第1期78-85,共8页
In sub nanometer carbon nanotubes,water exhibits unique dynamic characteristics,and in the high-frequency region of the infrared spectrum,where the stretching vibrations of the internal oxygen-hydrogen(O-H)bonds are c... In sub nanometer carbon nanotubes,water exhibits unique dynamic characteristics,and in the high-frequency region of the infrared spectrum,where the stretching vibrations of the internal oxygen-hydrogen(O-H)bonds are closely related to the hydrogen bonds(H-bonds)network between water molecules.Therefore,it is crucial to analyze the relationship between these two aspects.In this paper,the infrared spectrum and motion characteristics of the stretching vibrations of the O-H bonds in one-dimensional confined water(1DCW)and bulk water(BW)in(6,6)single-walled carbon nanotubes(SWNT)are studied by molecular dynamics simulations.The results show that the stretching vibrations of the two O-H bonds in 1DCW exhibit different frequencies in the infrared spectrum,while the O-H bonds in BW display two identical main frequency peaks.Further analysis using the spring oscillator model reveals that the difference in the stretching amplitude of the O-H bonds is the main factor causing the change in vibration frequency,where an increase in stretching amplitude leads to a decrease in spring stiffness and,consequently,a lower vibration frequency.A more in-depth study found that the interaction of H-bonds between water molecules is the fundamental cause of the increased stretching amplitude and decreased vibration frequency of the O-H bonds.Finally,by analyzing the motion trajectory of the H atoms,the dynamic differences between 1DCW and BW are clearly revealed.These findings provide a new perspective for understanding the behavior of water molecules at the nanoscale and are of significant importance in advancing the development of infrared spectroscopy detection technology. 展开更多
关键词 one-dimensional confined water infrared spectroscopy hydrogen bonds
在线阅读 下载PDF
Unveiling solid-solid contact states in all-solid-state lithium batteries:An electrochemical impedance spectroscopy viewpoint 被引量:1
17
作者 Jin-Liang Li Liang Shen +9 位作者 Zi-Ning Cheng Jun-Dong Zhang Ling-Xuan Li Yu-Tong Zhang Yan-Bin Gao Chunli Guo Xiang Chen Chen-Zi Zhao Rui Zhang Qiang Zhang 《Journal of Energy Chemistry》 2025年第2期16-22,I0002,共8页
All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid... All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental approach.This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs.With the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery impedance.Through accurate fitting,inverse proportional relations between contact resistance Rcand(1-porosity)as well as crack angle was disclosed.This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs. 展开更多
关键词 Electrochemical impedance spectroscopy All-solid-state lithium batteries Solid-solid contacts Finite element method Equivalent circuit model Distribution of relaxation times
在线阅读 下载PDF
Optical Spectroscopy Methods for Determining Semiconductor Bandgaps
18
作者 ZHANG Yong 《发光学报》 北大核心 2025年第7期1271-1282,共12页
Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic a... Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic absorption,(2)modulation spectroscopy,and(3)the most widely used Tauc-plot.The excitonic absorption is based on a many-particle theory,which is physically the most correct approach,but requires more stringent crystalline quality and appropriate sample preparation and experimental implementation.The Tauc-plot is based on a single-particle theo⁃ry that neglects the many-electron effects.Modulation spectroscopy analyzes the spectroscopy features in the derivative spectrum,typically,of the reflectance and transmission under an external perturbation.Empirically,the bandgap ener⁃gy derived from the three approaches follow the order of E_(ex)>E_(MS)>E_(TP),where three transition energies are from exci⁃tonic absorption,modulation spectroscopy,and Tauc-plot,respectively.In principle,defining E_(g) as the single-elec⁃tron bandgap,we expect E_(g)>E_(ex),thus,E_(g)>E_(TP).In the literature,E_(TP) is often interpreted as E_(g),which is conceptual⁃ly problematic.However,in many cases,because the excitonic peaks are not readily identifiable,the inconsistency be⁃tween E_(g) and E_(TP) becomes invisible.In this brief review,real world examples are used(1)to illustrate how excitonic absorption features depend sensitively on the sample and measurement conditions;(2)to demonstrate the differences between E_(ex),E_(MS),and E_(TP) when they can be extracted simultaneously for one sample;and(3)to show how the popular⁃ly adopted Tauc-plot could lead to misleading results.Finally,it is pointed out that if the excitonic absorption is not ob⁃servable,the modulation spectroscopy can often yield a more useful and reasonable bandgap than Tauc-plot. 展开更多
关键词 semiconductor material bandgap excitonic absorption modulation spectroscopy Tauc plot
在线阅读 下载PDF
Oxidative Degradation of Plastic Bottle Tops in an Arid, Terrestrial Environment—Identifying Oxidative Degradation by Infrared Spectroscopy
19
作者 Mahra Al Kaabi Vijo Poulose Thies Thiemann 《Journal of Environmental Protection》 2025年第2期66-86,共21页
This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectr... This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectroscopy. It is noted that while different bottle top types photo-oxidize at different rates, all show an appreciable level of oxidation after half a year of exposure to the environment. The oxidation leads to brittleness of the plastic, which leads to fissure formation in bottle tops of little thickness. This leads to fragmentation of the material upon impact, making plastic bottle tops an appreciable source of microplastics. 展开更多
关键词 PLASTICS Polythene POLYPROPYLENE Plastic Bottle Tops FRAGMENTATION Microplastics Infrared spectroscopy Oxidation Index
在线阅读 下载PDF
Review of imaging buffers used in stochastic optical reconstruction microscopy
20
作者 Can Wang Zhe Sun Donghan Ma 《Chinese Chemical Letters》 2025年第9期56-63,共8页
Stochastic optical reconstruction microscopy(STORM),as a typical technique of single-molecule localization microscopy(SMLM),has overcome the diffraction limit by randomly switching fluorophores between fluorescent and... Stochastic optical reconstruction microscopy(STORM),as a typical technique of single-molecule localization microscopy(SMLM),has overcome the diffraction limit by randomly switching fluorophores between fluorescent and dark states,allowing for the precise localization of isolated emission patterns and the super-resolution reconstruction from millions of localized positions of single fluorophores.A critical factor influencing localization precision is the photo-switching behavior of fluorophores,which is affected by the imaging buffer.The imaging buffer typically comprises oxygen scavengers,photo-switching reagents,and refractive index regulators.Oxygen scavengers help prevent photobleaching,photo-switching reagents assist in facilitating the conversion of fluorophores,and refractive index regulators are used to adjust the refractive index of the solution.The synergistic interaction of these components promotes stable blinking of fluorophores,reduces irreversible photobleaching,and thereby ensures high-quality super-resolution imaging.This review provides a comprehensive overview of the essential compositions and functionalities of imaging buffers used in STORM,serving as a valuable resource for researchers seeking to select appropriate imaging buffers for their experiments. 展开更多
关键词 Single-molecule localization microscopy Stochastic optical reconstruction microscopy Photo-switching Photobleaching Imaging buffer
原文传递
上一页 1 2 250 下一页 到第
使用帮助 返回顶部