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Drying process of water in a Nafion membrane embedded in the fuel cell analyzed by coherent anti-Stokes Raman scattering spectroscopy
摘要： A coherent anti-Stokes Raman scattering (CARS) spectroscopy system was designed to measure the transient behavior of the humidi?cation of a Na?on membrane used in a polymer electrolyte fuel cell (PEFC). We observed a variation in the intensity of the O–H stretching vibration peak of water during dry and wet gas ?ow. From our measurements, we found that our system showed a high time resolution enough to measure humidi?cation variation in a Na?on membrane in a PEFC. The high acquisition rate revealed the nonequilibrium process of the dehydration or hydration of the Na?on membrane through the temporal variation in the intensity of the O–H stretching vibration peak. The peak consisted of three peaks, suggesting that water molecules hydrated with di?erent bonding energies. The transient behavior of the peaks was probably attributed to the motion of hydration molecules in the proton channel. ? 2018 The Japan Society of Applied Physics
关键词： CARS spectroscopy,O–H stretching vibration,hydration,Na?on membrane,PEFC
更新于2025-09-04 15:30:14
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Study of the Interface of the Early Stages of Growth under Quasi-Equilibrium Conditions of ZnO on Graphene/Cu and Graphite
摘要： The study of the early stages of growth of ZnO on graphene supported on Cu and on highly oriented pyrolytic graphite by means of reactive thermal evaporation of metallic Zn at room temperature is presented. This growth method allows to go in depth in the study of the fundamental interaction between ZnO and graphene at the interface in quasi-equilibrium conditions. Quantitative, chemical, and morphological analysis is performed using photoemission spectroscopy, atomic force, and scanning microscopies as experimental characterization techniques and factor analysis and inelastic peak shape analysis as modeling techniques. The growth of ZnO on a highly oriented pyrolytic graphite substrate is also studied using the same growth method for comparison. The results show that, in spite that the first atomic layer of both substrates is identical, the growth kinetics and morphology of the deposits are completely different. A model for the kinetics of the growth of ZnO on both substrates is proposed.
关键词： X-ray photoemission spectroscopy,early stages of growth,ZnO/graphene interfaces,atomic force microscopy,nanostructured ZnO thin films
更新于2025-09-04 15:30:14
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Hydrogen bound water profiles in the skin influenced by optical clearing molecular agents- quantitative analysis using confocal Raman microscopy
摘要： Confocal Raman microscopy (CRM) has been used to measure depth-dependent profiles of porcine skin ex vivo in the high wavenumber region after application of molecular optical clearing agents (OCAs). Glycerol (70%) and iohexol (100% Omnipaque? (300)) water solutions were used as OCAs and topically applied to porcine ear skin for 30 and 60 min. Using Gaussian function–based deconvolution, the changes of hydrogen bound water molecule types have been microscopically analyzed down to the depth of 200 μm. Results show that both OCAs induced skin dehydration (reduction of total water), which is 51.3% for glycerol (60 min), 33.1% for glycerol (30 min), 8.3% for Omnipaque? (60 min), and 4.4% for Omnipaque? (30 min), on average for the 40–200 μm depths. Among the water types in the skin, the following reduction was observed in concentration of weakly bound (51.1%, 33.2%, 7.5%, and 4.6%), strongly bound (50.4%, 33.0%, 7.9%, and 3.4%), tightly bound (63.6%, 42.3%, 26.1%, and 12.9%) and unbound (55.4%, 28.7%, 10.1%, and 5.9%) water types on average for the 40–200 μm depths, post application of glycerol (60 min), glycerol (30 min), Omnipaque? (60 min), and Omnipaque? (30 min), respectively. As most concentrated in the skin, weakly and strongly bound water types are preferentially involved in the OCA-induced water flux in the skin, and thus, are responsible for optical clearing efficiency.
关键词： dermis,glycerol,skin barrier,Omnipaque?,epidermis,iohexol,Raman spectroscopy
更新于2025-09-04 15:30:14
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Simultaneous <i>in vivo</i> optical quantification of key metabolic and vascular endpoints reveals tumor metabolic diversity in murine breast tumor models
摘要： Therapeutically exploiting vascular and metabolic endpoints becomes critical to translational cancer studies because altered vascularity and deregulated metabolism are two important cancer hallmarks. The metabolic and vascular phenotypes of three sibling breast tumor lines with different metastatic potential are investigated in vivo with a newly developed quantitative spectroscopy system. All tumor lines have different metabolic and vascular characteristics compared to normal tissues, and there are strong positive correlations between metabolic (glucose uptake and mitochondrial membrane potential) and vascular (oxygen saturations and hemoglobin concentrations) parameters for metastatic (4T1) tumors but not for micro-metastatic (4T07) and non-metastatic (67NR) tumors. A longitudinal study shows that both vascular and metabolic endpoints of 4T1 tumors increased up to a specific tumor size threshold beyond which these parameters decreased. The synchronous changes between metabolic and vascular parameters, along with the strong positive correlations between these endpoints suggest that 4T1 tumors rely on strong oxidative phosphorylation in addition to glycolysis. This study illustrates the great potential of our optical technique to provide valuable dynamic information about the interplay between the metabolic and vascular status of tumors, with important implications for translational cancer investigations.
关键词： tumor metabolism,Optical spectroscopy,vascular microenvironment,tumor metastasis
更新于2025-09-04 15:30:14
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Raman spectroscopy analysis of new copper‐cysteamine photosensitizer
摘要： Raman spectroscopy and several microstructure analysis techniques have been used to better characterize recently synthesized copper‐cysteamine Cu3Cl(SR)2, where R = CH2CH2NH2. Nanoparticles of this new copper‐cysteamine have been identified as having potential applications in radiation detection and cancer treatment because of the fact that they can be activated by light, X‐rays, ultrasound, and microwave radiation to produce reactive oxygen species. Three samples were grown under different conditions, and their microstructure was examined by using Raman spectroscopy, Fourier transform infrared, scanning electron microscopy, energy dispersive X‐ray scattering, and X‐ray diffraction. The Raman spectroscopy and Fourier transform infrared measurements identify numerous Raman active and infrared absorption bonds with wavenumbers ranging from 200 to 3,500 cm?1. Scanning electron microscopy scans show well‐faceted crystals varying in size from approximately 10 nm to 4 μm, energy dispersive X‐ray scattering measurements identify relative elemental composition (C = 48%, N = 37.5%, S = 5%, Cl = 2.6%, Cu = 7%), X‐ray diffraction data show the crystal plane spacing varies from 0.8454 to 0.8616 nm. The microstructure observed for the three samples is consistent with variations in the growth conditions.
关键词： microstructure,optical spectroscopy of interatomic bonds,cancer treatment,radiation detection,copper‐cysteamine
更新于2025-09-04 15:30:14
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Direct Synthesis of Gold Nanoparticle‐Over‐Nanosheet for Sensitive SERS Detection
摘要： A simple ethanol sol-based method for the synthesis of gold nanosheets (AuNSs) and gold nanoparticle-over-nanosheet (AuNP/NS) is developed. Gold nanoparticles (AuNPs) with average sizes of ≈8 nm are grown in situ on the surface of the AuNS, which forms a NP/NS structure that obtains strong, significantly improved, surface-enhanced Raman spectroscopy activity with the magnitude ≈2 and ≈6 orders higher than the simplex AuNP and AuNS, respectively. This performance is mainly attributed to uniform AuNPs that are closely packed over AuNS and coupled with NP–NS and NP–NP interactions. The NP–NS–GP (the gap between NP–NS) is narrower than NP–NP–GP in which much stronger and steadier plasmon resonance is obtained that can significantly enhance the Raman signal. The results show that single-crystalline AuNS is an ideal substrate, which can be further coated with other metallic NPs to form a new flexible, high-activity and AuNS-based nanocomposite for a wide variety of applications.
关键词： gold nanoparticle-over-nanosheet (AuNP/NS) composite,2D gold nanosheet (AuNS),surface-enhanced Raman spectroscopy (SERS)
更新于2025-09-04 15:30:14
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Dual Path Lock-In System for Elimination of Residual Amplitude Modulation and SNR Enhancement in Photoacoustic Spectroscopy
摘要： A technique for elimination of residual amplitude modulation (ERAM) in photoacoustic spectroscopy based on dual path lock-in was proposed and experimentally demonstrated. There are two lock-in amplifiers, one is for gas concentration demodulation and another for residual amplitude modulation (RAM) measurement by tuning the reference signal in different phases, and then a dual path lock-in technique based on subtraction is applied to RAM removal, improving the second harmonic profile significantly. In this system, the signal to noise ratio (SNR) increases about two times based on our dual path lock-in technique compared to one distributed feedback laser diode (DFB-LD). The system achieved a good linear response (R-square = 0.99887) in a concentration range from 100 ppmv to 2400 ppmv and a minimum detection limit (MDL) of 1.47 ppmv.
关键词： photoacoustic spectroscopy,RAM,dual path lock-in
更新于2025-09-04 15:30:14
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Handbook of Advanced Non-Destructive Evaluation || Terahertz Techniques in NDE
摘要： So far, terahertz measurement technology has rarely been used in industry. This book chapter presents therefore the underlying technologies, the resulting possibilities and exemplary applications. The introduction describes the basic properties of terahertz systems and the advantages of terahertz technology over established techniques such as infrared, X-rays and ultrasound. The two industrially relevant terahertz techniques, time domain spectrometer and FMCW system, are described in detail. In addition, the metrological basics for their main applications are introduced. Imaging is required in many applications. Different approaches are presented. Before the chapter concludes with an outlook on future applications, current application examples are discussed. This concerns applications in the fields of coating thickness measurement, safety, materials research, testing of lightweight materials and inline testing. An extensive reference list provides a deeper insight into the topics addressed.
关键词： lightweight materials,materials research,coating thickness measurement,terahertz,NDE,FMCW,imaging,inline testing,time-domain spectroscopy
更新于2025-09-04 15:30:14
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Total soil carbon assessment: linking field, lab, and landscape through VNIR modelling
摘要： Context Point based measurements provide only a limited overview of landscape variation in measured properties. Upscaling of measurements from point to landscape comes with challenges particularly considering error propagation. Objectives We investigated the impact of using proximal derived measurements of soil total carbon taken at point locations on upscaling to landscape levels. Methods 1087 soil samples across Florida, USA were collected, laboratory (LAB) analysed for total carbon (TC), and then measured using visible-/near-infrared (VNIR) spectroscopy. Proximal TC values were generated through chemometric modelling using random forest (RF) and partial least squares (PLS) regression. These three datasets were then upscaled to the State of Florida, USA using ordinary kriging and compared. Results R2 (RPD) values for the PLS and RF chemometric models were 88% (2.96) and 91% (3.23), respectively. All 3 spatial models had an accuracy of 54% on an independent validation dataset, with greater than 70% accuracy if predicted values were considered within the interpolation variance range. When comparing spatial interpolations derived from the proximally measured samples, only 18% of the PLS versus 51% of the RF fell within a range of 0.05 logTC (g kg-1) of the LAB measured interpolations. Conclusions Using proximal sampling and modelling provides comparable output to laboratory measured soil TC measurements at point level, but when upscaled to landscape level the selection of proximal modelling method will impact the spatial interpolations derived. The error propagation within sequential modelling must be considered particularly when one wishes to use sequential modelling to analyse change in environmental properties.
关键词： Geostatistics,Proximal sampling,Error propagation,Total carbon (TC),Spectroscopy,Upscaling
更新于2025-09-04 15:30:14
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Synthesis, structural and optical‐vibration properties of Ba <sub/>3</sub> Sc <sub/>4</sub> O <sub/>9</sub> and Sr <sub/>3</sub> Sc <sub/>4</sub> O <sub/>9</sub> ceramics
摘要： Ba3Sc4O9 and Sr3Sc4O9 ceramics were synthesized by conventional solid‐state reactions at 1200°C, being further sintered at 1300°C in order to produce ceramic bodies suitable for exploring their structural and optical vibration properties. Optimized experimental conditions were employed to unveil the complex vibrational spectra of these ceramics by polarized Raman scattering. A reliable and comprehensive set of phonon features was obtained from these experiments: The 30 theoretically expected optically active lattice modes for each material were in fact observed, from which 15 could be assigned as totally symmetric A‐polar modes and 15 attributed as degenerate (and asymmetric) E‐polar ones. Differences between experimental data of Ba‐containing and Sr‐containing samples are discussed in terms of their ionic radii and molar masses. The knowledge of the optical phonon features reported here can help to understand the exceptional luminescence properties of Ba3Sc4O9 and Sr3Sc4O9 rhombohedral phases when doped with trivalent ions, as recently reported by the literature.
关键词： luminescence,ceramics,phosphors,Ba3Sc4O9 and Sr3Sc4O9,polarization‐resolved Raman spectroscopy
更新于2025-09-04 15:30:14