期刊文献+
共找到41,816篇文章
< 1 2 250 >
每页显示 20 50 100
Optical Frequency Comb-Based Cavity-Enhanced Fourier-Transform Spectroscopy:Application to Collisional Line-Shape Study
1
作者 Akiko Nishiyama Grzegorz Kowzan +2 位作者 Dominik Charczun Ryszard S.Trawinski Piotr Mas lowski 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第1期23-30,共8页
Direct-comb spectroscopy techniques uses optical frequency combs(OFCs)as spectroscopic light source.They deliver high sensitivity,high frequency resolution and precision in a broad spectral range.Due to these features... Direct-comb spectroscopy techniques uses optical frequency combs(OFCs)as spectroscopic light source.They deliver high sensitivity,high frequency resolution and precision in a broad spectral range.Due to these features,the field has burgeoned in recent years.In this work we constructed an OFC-based cavity-enhanced Fourier-transform spectrometer in the nearinfrared region and used it for a line-shape study of rovibrational transitions of CO perturbed by Ar.The highly sensitive measurements spanned the wavenumber range from 6270 cm^-1 to 6410 cm^-1,which covered both P and R branch of the second overtone band of CO.The spectrometer delivers high-resolution surpassing the Fourier-transform resolution limit determined by interferogram length,successfully removing ringing and broadening effects caused by instrumental line shape function.The instrumental-line-shape-free method and high signal-to-noise ratio in the measurement allowed us to observe collisional effects beyond those described by the Voigt profile.We retrieved collisional line-shape parameters by fitting the speed-dependent Voigt profile and found good agreement with the values given by precise cavity ring-down spectroscopy measurements that used a continuous-wave laser referenced to a stabilized OFC.The results demonstrate that OFC-based cavity-enhanced Fouriertransform spectroscopy is a strong tool for accurate line-shape studies that will be crucial for future spectral databases. 展开更多
关键词 Carbon monoxide Spectral lineshapes Optical frequency comb Cavity enhanced absorption spectroscopy fourier-transform spectroscopy
在线阅读 下载PDF
Tender energy spectroscopy beamline at the Shanghai Synchrotron Radiation Facility
2
作者 Shu‑Min Yang Ling‑Ling Guo +12 位作者 Bing Nan Ying Zhao Yan‑Qing Wu Zhi Guo Chen Tian Bo Zhao Chao‑Fan Xue Jun Zhao Shuang Song Zhen‑Ye Liang Li‑Na Li Yong Wang Ren‑Zhong Tai 《Nuclear Science and Techniques》 2026年第1期94-106,共13页
This paper describes the design and performance of the tender energy spectroscopy beamline(BL16U1),a phase Ⅱ beamline,at the Shanghai Synchrotron Radiation Facility.The beamline,based on an in-vacuum undulator source... This paper describes the design and performance of the tender energy spectroscopy beamline(BL16U1),a phase Ⅱ beamline,at the Shanghai Synchrotron Radiation Facility.The beamline,based on an in-vacuum undulator source with 26 mm period,provides an operable energy range between 2.1 keV and 16 keV,covering the K-edges of P to Rb and L3-edges of Zr to Bi.The principal optical elements of the beamline are a toroidal mirror,a liquid nitrogen-cooled double-crystal monochromator,a high-harmonic-rejection mirror,and two pairs of Kirkpatrick–Baez(KB)mirrors.Three end-stations,including non-focusing,microprobe,and sub-microprobe types,are installed on the beamline.X-ray fluorescence(XRF)and X-ray absorption spectroscopy(XAS),including X-ray absorption near-edge structure(XANES)and extended X-ray absorption fine structure(EXAFS),are performed under vacuum or He atmosphere at the non-focusing end-station(with a beam spot size of∼670μm×710μm).Using two KB mirrors systems,micro-XRF(μXRF)mapping and micro-XANES(μXANES)studies can be performed with a spot size of approximately∼3.3μm×1.3μm at the microprobe end-station and with a smaller spot size of∼0.5μm×0.25μm at the sub-microprobe end-station.The non-focusing end-station was officially opened to users in January 2024.The microprobe and sub-microprobe end-stations will be opened to users in the near future.This paper presents the characteristics,short-term technical developments,and early experimental results of this new beamline. 展开更多
关键词 Tender energy X-ray spectroscopy X-ray fluorescence SSRF X-ray absorption spectroscopy(XAS) MICROPROBE
在线阅读 下载PDF
Commissioning of a radiofrequency quadrupole cooler‑buncher for collinear laser spectroscopy
3
作者 Yin‑Shen Liu Han‑Rui Hu +15 位作者 Xiao‑Fei Yang Wen‑Cong Mei Yang‑Fan Guo Zhou Yan Shao‑Jie Chen Shi‑Wei Bai Shu‑Jing Wang Yong‑Chao Liu Peng Zhang Dong‑Yang Chen Yan‑Lin Ye Qi‑Te Li Jie Yang Stephan Malbrunot‑Ettenauer Simon Lechner Carina Kanitz 《Nuclear Science and Techniques》 2026年第1期193-201,共9页
A RadioFrequency Quadrupole(RFQ)cooler-buncher system was developed and implemented in a collinear laser spectroscopy setup.This system converts a continuous ion beam into short bunches while enhancing the beam qualit... A RadioFrequency Quadrupole(RFQ)cooler-buncher system was developed and implemented in a collinear laser spectroscopy setup.This system converts a continuous ion beam into short bunches while enhancing the beam quality and reducing the energy spread.The functionality of the RFQ cooler buncher was verified through offline tests with stable rubidium and indium beams delivered from a surface ion source and a laser ablation ion source,respectively.Bunched ion beams with a full width at half maximum of approximately 2μs in the time-of-flight spectrum were successfully achieved with a transmission efficiency exceeding 60%.The implementation of the RFQ cooler-buncher system also significantly improved the overall transmission efficiency of the collinear laser spectroscopy setup. 展开更多
关键词 Radiofrequency quadrupole cooler-buncher Collinear laser spectroscopy Hyperfine structure Time of flight
在线阅读 下载PDF
The evolving role of Fourier-transform midinfrared spectroscopy in genetic improvement of dairy cattle 被引量:3
4
作者 K.M.Tiplady T.J.Lopdell +1 位作者 M.D.Littlejohn D.J.Garrick 《Journal of Animal Science and Biotechnology》 CAS CSCD 2020年第3期626-638,共13页
Over the last 100 years,significant advances have been made in the characterisation of milk composition for dairy cattle improvement programs.Technological progress has enabled a shift from labour intensive,on-farm co... Over the last 100 years,significant advances have been made in the characterisation of milk composition for dairy cattle improvement programs.Technological progress has enabled a shift from labour intensive,on-farm collection and processing of samples that assess yield and fat levels in milk,to large-scale processing of samples through centralised laboratories,with the scope extended to include quantification of other traits.Fourier-transform midinfrared(FT-MIR)spectroscopy has had a significant role in the transformation of milk composition phenotyping,with spectral-based predictions of major milk components already being widely used in milk payment and animal evaluation systems globally.Increasingly,there is interest in analysing the individual FT-MIR wavenumbers,and in utilising the FT-MIR data to predict other novel traits of importance to breeding programs.This includes traits related to the nutritional value of milk,the processability of milk into products such as cheese,and traits relevant to animal health and the environment.The ability to successfully incorporate these traits into breeding programs is dependent on the heritability of the FT-MIR predicted traits,and the genetic correlations between the FT-MIR predicted and actual trait values.Linking FT-MIR predicted traits to the underlying mutations responsible for their variation can be difficult because the phenotypic expression of these traits are a function of a diverse range of molecular and biological mechanisms that can obscure their genetic basis.The individual FT-MIR wavenumbers give insights into the chemical composition of milk and provide an additional layer of granularity that may assist with establishing causal links between the genome and observed phenotypes.Additionally,there are other molecular phenotypes such as those related to the metabolome,chromatin accessibility,and RNA editing that could improve our understanding of the underlying biological systems controlling traits of interest.Here we review topics of importance to phenotyping and genetic applications of FT-MIR spectra datasets,and discuss opportunities for consolidating FT-MIR datasets with other genomic and molecular data sources to improve future dairy cattle breeding programs. 展开更多
关键词 Bovine milk Cattle breeding genetics fourier-transform infrared spectroscopy Trait prediction
在线阅读 下载PDF
Use of Fourier-transform infrared spectroscopy to rapidly diagnose gastric endoscopic biopsies 被引量:1
5
作者 Qing-BoLi Xue-JunSun +5 位作者 Yi-ZhuangXu Li-MinYang Yuan-FuZhang Shi-FuWeng Jing-SenShi Jin-GuangWu 《World Journal of Gastroenterology》 SCIE CAS CSCD 2005年第25期3842-3845,共4页
AIM: To determine if Fourier-transform infrared (FT-IR)spectroscopy of endoscopic biopsies could accurately diagnose gastritis and malignancy.METHODS: A total of 123 gastroscopic samples, including 11 cases of cancero... AIM: To determine if Fourier-transform infrared (FT-IR)spectroscopy of endoscopic biopsies could accurately diagnose gastritis and malignancy.METHODS: A total of 123 gastroscopic samples, including 11 cases of cancerous tissues, 63 cases of chronic atrophic gastritis tissues, 47 cases of chronic superficial gastritis tissues and 2 cases of normal tissues, were obtained from the First Hospital of Xi'an Jiaotong University, China. A modified attenuated total reflectance (ATR) accessory was linked to a WQD-500 FT-IR spectrometer for spectral measurement followed by submission of the samples for pathologic analysis. The spectral characteristics for different types of gastroscopic tissues were summarized and correlated with the corresponding pathologic results.RESULTS: Distinct differences were observed in the FTIR spectra of normal, atrophic gastritis, superficial gastritis and malignant gastric tissues. The sensitivity of FT-IR for detection of gastric cancer, chronic atrophic gastritis and superficial gastritis was 90.9%, 82.5%, 91.5%, and specificity was 97.3%, 91.7%, 89.5% respectively.CONCLUSION: FT-IR spectroscopy can distinguish gastric inflammation from malignancy. 展开更多
关键词 fourier-transform infrared spectroscopy Gastric endoscope Gastric cancer Chronic gastritis Spectral analysis Infrared detection
暂未订购
Study on the Hydrogen Bond Interaction Between Soy Protein Isolate and Glycerol Using Two-Dimensional Correlation Fourier-Transform Infrared Spectroscopy
6
作者 YAN Zhi-wei YANG He-li ZHANG Pu-dun 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2016年第S1期85-86,共2页
A series of soy protein isolate(SPI)films plasticized by glycerol(Gly)were studied using attenuated total reflectance-Fourier transform infrared spectroscopy(ATR/FTIR).Perturbation-correlation movingwindow two-dimensi... A series of soy protein isolate(SPI)films plasticized by glycerol(Gly)were studied using attenuated total reflectance-Fourier transform infrared spectroscopy(ATR/FTIR).Perturbation-correlation movingwindow two-dimensional(PCMW2D)and two-dimensional correlation(2DCOS)analyses were applied to the amideⅠband and thus the hydrogen bond interaction between SPI and Gly was systematically investigated.When Gly concentrations were in the range 0~35%,the hydrogen bond amongβ-sheets was replaced by the one between SPI chain and Gly molecule,which caused these protein chains being changed toα-helix.However,the transformation ofβ-sheet toα-helix was saturated and both of them tend to change to random coil when Gly concentrations were in the range 35%~60%. 展开更多
关键词 Two-dimensional correlation infrared spectroscopy Soy protein isolate GLYCEROL Hydrogen bond interaction
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
Identification of active sites for hydrogenation over Ru/SBA-15 using in situ Fourier-transform infrared spectroscopy
8
作者 Hangjia Shen Xianyuan Wu +2 位作者 Dahao Jiang Xiaonian Li Jun Ni 《Chinese Journal of Catalysis》 CSCD 北大核心 2017年第9期1597-1602,共6页
The active sites for hydrogenation over Ru/SBA‐15catalysts were identified using in situ Fourier‐transform infrared spectroscopy.The amount of active sites was proportional to the interfacial circumference of the Ru... The active sites for hydrogenation over Ru/SBA‐15catalysts were identified using in situ Fourier‐transform infrared spectroscopy.The amount of active sites was proportional to the interfacial circumference of the Ru particles.In contrast,the rate of hydrogen spillover from Ru to the support was inversely proportional to the size of the Ru metal particles.Consequently,a catalyst with small Ru metal particles has a high rate of hydrogen spillover but a low density of active sites,whereas one with large Ru particles has a low rate of hydrogen spillover but a high density of active sites.The formation of these active sites is probably an intermediate step in hydrogen spillover. 展开更多
关键词 Ru/SBA‐15 catalyst In‐situ Fourier‐transform infrared spectroscopy HYDROGENATION Active site Hydrogen spillover
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
Rapid pathologic grading-based diagnosis of esophageal squamous cell carcinoma via Raman spectroscopy and a deep learning algorithm 被引量:1
11
作者 Xin-Ying Yu Jian Chen +2 位作者 Lian-Yu Li Feng-En Chen Qiang He 《World Journal of Gastroenterology》 2025年第14期32-46,共15页
BACKGROUND Esophageal squamous cell carcinoma is a major histological subtype of esophageal cancer.Many molecular genetic changes are associated with its occurrence.Raman spectroscopy has become a new method for the e... BACKGROUND Esophageal squamous cell carcinoma is a major histological subtype of esophageal cancer.Many molecular genetic changes are associated with its occurrence.Raman spectroscopy has become a new method for the early diagnosis of tumors because it can reflect the structures of substances and their changes at the molecular level.AIM To detect alterations in Raman spectral information across different stages of esophageal neoplasia.METHODS Different grades of esophageal lesions were collected,and a total of 360 groups of Raman spectrum data were collected.A 1D-transformer network model was proposed to handle the task of classifying the spectral data of esophageal squamous cell carcinoma.In addition,a deep learning model was applied to visualize the Raman spectral data and interpret their molecular characteristics.RESULTS A comparison among Raman spectral data with different pathological grades and a visual analysis revealed that the Raman peaks with significant differences were concentrated mainly at 1095 cm^(-1)(DNA,symmetric PO,and stretching vibration),1132 cm^(-1)(cytochrome c),1171 cm^(-1)(acetoacetate),1216 cm^(-1)(amide III),and 1315 cm^(-1)(glycerol).A comparison among the training results of different models revealed that the 1Dtransformer network performed best.A 93.30%accuracy value,a 96.65%specificity value,a 93.30%sensitivity value,and a 93.17%F1 score were achieved.CONCLUSION Raman spectroscopy revealed significantly different waveforms for the different stages of esophageal neoplasia.The combination of Raman spectroscopy and deep learning methods could significantly improve the accuracy of classification. 展开更多
关键词 Raman spectroscopy Esophageal neoplasia Early diagnosis Deep learning algorithm Rapid pathologic grading
暂未订购
Coulomb attraction driven spontaneous molecule-hotspot pairing enables universal,fast,and large-scale uniform single-molecule Raman spectroscopy 被引量:1
12
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
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
Using deep learning to reduce nonlinearity effects in nearinfrared spectroscopy for accurate quantification of tobacco leaf pectin concentrations
14
作者 Wenhui Yang Limin Shao 《中国科学技术大学学报》 北大核心 2025年第6期57-66,56,I0002,共12页
In the near-infrared(NIR)spectroscopic data of complex sample systems,such as tobacco leaves,nonlinearity is fairly significant between the absorbance and concentration.This nonlinearity severely degrades the quantita... In the near-infrared(NIR)spectroscopic data of complex sample systems,such as tobacco leaves,nonlinearity is fairly significant between the absorbance and concentration.This nonlinearity severely degrades the quantitative results of traditional methods,such as partial least squares regression(PLS),which can be used to construct linear models.The problem was addressed in this study by using deep learning(DL).We employed three different DL models:a one-dimensional convolutional neural network(1D CNN),a deep neural network(DNN),and a stacked autoencoder with feedforward neural networks(SAE-FNNs).By carefully selecting and tuning the architectures and parameters of these models,we were able to find the most suitable model for dealing with such nonlinear relationships.Our experimental findings reveal that both the DNN and the SAE-FNN models excel in addressing the nonlinear issues of pectin concentration in tobacco,surpassing the performance of the classic linear model(PLS).Specifically,the DNN model stands out for its low average root mean squared error of prediction(RMSEP)value and small standard deviation(SD)of RMSEPs,leading to a tighter and more centered distribution of residuals in the prediction set.These DL models not only proficiently identify complex patterns within NIR data but also boast high prediction accuracy and fast implementation,demonstrating their effectiveness in analytical applications. 展开更多
关键词 quantitative regression NONLINEARITY deep learning methods near-infrared spectroscopy
在线阅读 下载PDF
Infrared spectroscopic analysis of O-H bond dynamics in one-dimensional confined water and bulk water
15
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
16
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
17
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
18
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
Research on Denoising Method of Agricultural Product Terahertz Spectroscopy Based on Adaptive Signal Decomposition
19
作者 WU Jing-zhu LIU Yu-hao +3 位作者 YANG Yi XIE Chuan-luan L Zhong-ming LI Yi-can 《光谱学与光谱分析》 北大核心 2025年第12期3575-3584,共10页
To address the issues of peak overlap caused by complex matrices in agricultural product terahertz(THz)spectral signals and the dynamic,nonlinear interference induced by environmental and system noise,this study explo... To address the issues of peak overlap caused by complex matrices in agricultural product terahertz(THz)spectral signals and the dynamic,nonlinear interference induced by environmental and system noise,this study explores the feasibility of adaptive-signal-decomposition-based denoising methods to improve THz spectral quality.THz time-domain spectroscopy(THz-TDS)combined with an attenuated total reflection(ATR)accessory was used to collect THz absorbance spectra from 48 peanut samples.Taking the quantitative prediction model of peanut moisture content based on THz-ATR as an example,wavelet transform(WT),empirical mode decomposition(EMD),local mean decomposition(LMD),and its improved methods-segmented local mean decomposition(SLMD)and piecewise mirror extension local mean decomposition(PME-LMD)-were employed for spectral denoising.The applicability of different denoising methods was evaluated using a support vector regression(SVR)model.Experimental results show that the peanut moisture content prediction model constructed after PME-LMD denoising achieved the best performance,with a root mean square error(RMSE),coefficient of determination(R^(2)),and mean absolute percentage error(MAPE)of 0.010,0.912,and 0.040,respectively.Compared with traditional methods,PME-LMD significantly improved spectral quality and model prediction performance.The PME-LMD denoising strategy proposed in this study effectively suppresses non-uniform noise interference in THz spectral signals,providing an efficient and accurate preprocessing method for THz spectral analysis of agricultural products.This research provides theoretical support and technical guidance for the application of THz technology for detecting agricultural product quality. 展开更多
关键词 Terahertz spectroscopy Denoising method Agricultural products Support vector regression Piecewise mirror extension local mean decomposition
在线阅读 下载PDF
Dynamic surface-enhanced Raman spectroscopy-based metabolic profiling:A novel pathway to overcoming antifungal resistance
20
作者 Hao Li Hanzhi Lu +4 位作者 Linlin Hu Xueli Zhang Hua Shao Fulun Li Yanfei Shen 《Chinese Chemical Letters》 2025年第7期217-221,共5页
Antifungal resistance is the leading cause of antifungal treatment failure in invasive candidiasis.Metabolic rewiring could become a new insight to account for antifungal resistance as to find innovative clinical ther... Antifungal resistance is the leading cause of antifungal treatment failure in invasive candidiasis.Metabolic rewiring could become a new insight to account for antifungal resistance as to find innovative clinical therapies.Here,we show that dynamic surface-enhanced Raman spectroscopy is a promising tool to identify the metabolic differences between fluconazole(Diflucan)-resistant and fluconazole(Diflucan)-sensitive Candida albicans through the signatures of biochemical components and complemented with machine learning algorithms and two-dimensional correlation spectroscopy,an underlying resistance mechanism,that is,the change of purine metabolites induced the resistance of Candida albicans has been clarified yet never reported anywhere.We hope the integrated methodology introduced in this work could be beneficial for the interpretation of cellular regulation,propelling the development of targeted antifungal therapies and diagnostic tools for more efficient management of severe antifungal resistance. 展开更多
关键词 Antifungal resistance Metabolic rewiring Dynamic surface-enhanced Raman spectroscopy Machine learning Two-dimensional correlation spectroscopy
原文传递
上一页 1 2 250 下一页 到第
使用帮助 返回顶部