- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Chemical Analysis of Solid Insulation Degradation using the AFM-IR Technique
摘要： To enable the continued development of power transmission cabling, an understanding of the processes which result in their failures is essential. In order to do so, powerful analysis techniques are required. However, those which consider chemical degradation are lagging behind those for visible degradation. This paper presents the Atomic Force Microscopy - Infrared Spectroscopy (AFM-IR) chemical analysis technique, which can provide surface chemical analysis with resolution of ~50 nm across the infrared spectrum. Two cases are considered: interfacial tracking between epoxy and silicone rubber, and the degraded region formed in front of a needle tip in the electrical tree initiation process. The results obtained using AFM-IR are compared to the outcomes from other techniques. It is found that AFM-IR offers a unique and powerful insight into visible and non-visible degradation of solid dielectrics.
关键词： AFM-IR,epoxy,chemical analysis,interfacial tracking,Electrical treeing,degradation
更新于2025-09-23 15:22:29
-
Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis
摘要： This study describes a method to quantify the chemical composition of deep-sea hydrothermal deposits in situ using laser-induced breakdown spectroscopy (LIBS). Partial least squares (PLS) regression analysis is applied to spectra obtained using a long laser pulse with a duration of 150 ns. The number of measurements needed to address the spatial heterogeneity of samples is determined through high-resolution mapping of the elemental distribution in rock samples. PLS applied to laboratory measured seawater-submerged samples achieved an average relative error (RE) of 25% for Cu, Pb, and Zn compared to benchmark concentration values in cross-validation and validation studies, where both the benchmark concentration values and LIBS spectral data are made available with this publication. The PLS model was applied to LIBS signals obtained in situ from hydrothermal deposits at 1000 m depth in the ocean. The results show that target inhomogeneity limits the accuracy of the surface LIBS measurements compared to benchmark values from bulk analysis of samples. Making multiple measurements with small position offsets at each location improves the accuracy of estimates compared to an equivalent number of measurements at a single position. Maps of element distribution generated using quantified in situ data demonstrate how chemical survey outputs can be generated by combining LIBS with multivariate analysis. This enables real-time chemical feedback during deep-sea operations and chemical surveys in situations or with platforms where sample recovery is not possible.
关键词： Multivariate analysis,Laser-induced breakdown spectroscopy (LIBS),Deep-sea explorations,In situ chemical analysis,Seafloor mineral resources,Partial least squares regression analysis
更新于2025-09-23 15:19:57
-
Optimisation of the Quantification of Total Soluble Solids, pH and Titratable Acidity in South African Grape Must using Fourier Transform Mid-infrared Spectroscopy
摘要： Calibration models for Fourier transform mid-infrared (FT-MiR) spectroscopy were developed for the simultaneous quantification of total soluble solids (TSS, measured as °Brix), pH and titratable acidity (TA, expressed as g/L tartaric acid) in South African (SA) grape must. An exploratory data analysis of the FT-MIR spectra of 1170 grape must samples (647 for °Brix, 252 for pH and 271 for TA) was done by principal component analysis, and partial least squares regression was used for the computation of the regression models. The prediction errors for TSS (0.34 °Brix), pH (0.04 units) and TA (0.51 g/L) provided analytical data of satisfactory accuracy. The evaluation of ready-to-use global calibrations to quantify these three parameters in SA samples presented standard error of prediction (SEP) values of 0.46°Brix, 0.10 pH units and 3.13 g/L for TA. After slope and intercept adjustments of the original global calibration algorithms, the SEP values were reduced to 0.38 °Brix, 0.05 pH units and 0.49 g/L for TA. These results show the necessity for optimisation of the global FT-MIR WineScan calibrations to provide a better fit to samples of South African origin. The results demonstrate that FT-MiR spectroscopy is a useful technique for the rapid quantification of major grape must parameters and for quality control purposes in an industrial cellar.
关键词： wine grape chemical analysis,Fourier transform infrared spectroscopy,chemometrics
更新于2025-09-19 17:15:36
-
[OSA Optical Fiber Sensors - Lausanne (2018..-..)] 26th International Conference on Optical Fiber Sensors - Distributed hydrogen monitoring with phase-sensitive optical time-domain reflectometry
摘要： We propose a distributed hydrogen sensing system based on ?-OTDR and a novel coating configuration with fiber adhesively bonding to palladium foils. An ultra-high sensitive distributed hydrogen sensing with 5 cm spatial resolution is demonstrated.
关键词： Chemical analysis,Scattering, Rayleigh,Fiber optics sensors,Fiber optics
更新于2025-09-19 17:13:59
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - All — Fiber Evanescent Wave Sensors for the Mid-Infrared Spectroscopy of Liquids
摘要： Methods of the mid-IR spectroscopy provide reliable tools for detecting chemical composition of gases and liquids. In the mid-IR spectral range (wavelengths of 3-25 μm), various molecules and functional groups have fundamental absorption bands with large absorption coefficients. Creation of materials and technologies for the remote sensors consisting of fiber-optic broadband sources of coherent mid-IR radiation, chalcogenide fibers for transmitting light to the sensing elements and spectrally-selective photodetectors is a problem of a high scientific priority. In this work, we develop the fiber-optic analytical spectroscopy for chemical analysis of aqueous solutions of acetone, ethanol, for determination of the fractional chemical composition of hydrocarbons. As a material base for the fiber-optic sensors, chalcogenide fibers with an extremely low content of impurities have been designed and fabricated by single- and double-crucible methods (including the REE-doped glass fibers). By using these fibers, technologies of fabrication of permanent fiber bends, tapers, microstructured fibers have been developed for using these structures in fiber lasers, supercontinuum generators, sensing elements. A theoretical approach based on electromagnetic theory of optical fibers has been applied for computer-aided design of the evanescent-wave sensors. A sensing element shaped as the U-bent fiber that was applied for chemical analysis of liquid consisting of a diesel oil and a fuel additive is shown. For chemical analysis, the absorption band at the wavelength of 7.83 μm, corresponding to esters, has been chosen. Output characteristics of the sensor were studied in experiment by variation of the fiber core diameter and the bend radius. In a computer model, it was shown that attenuation coefficients of evanescent modes propagating in the fiber bend grow with increase of the bend radius and with decrease of the fiber core diameter. This allows for enhancing sensitivity and decreasing the minimum detectable amount of an analyte. In fact, with an optimised sensing element, the minimum detected amount of the fuel additive was less than 0.1 vol.%.
关键词： evanescent-wave sensors,chalcogenide fibers,chemical analysis,fiber-optic sensors,mid-IR spectroscopy
更新于2025-09-12 10:27:22
-
Synchrotron infrared nanospectroscopy on a graphene chip
摘要： A recurring goal in biology and biomedicine research is to access the biochemistry of biological processes in liquids that represent the environmental conditions of living organisms. These demands are becoming even more specific as microscopy techniques are fast evolving to the era of single cells analysis. In the modality of chemical probes, synchrotron infrared spectroscopy (μ-FTIR) is a technique that is extremely sensitive to vibrational response of materials, however, the classical optical limits prevent the technique to access the biochemistry of specimens in the subcellular level. In addition, due to the intricate environmental requirements and strong infrared absorption of water, μ-FTIR of bioprocess in liquids remains highly challenging. In phase with those challenges, on-chip liquid cells emerge as a versatile alternative to control the water thickness while providing a biocompatible chemical environment for analytical analyzes. In this work we report the development of a liquid platform specially designed for nanoscale infrared analysis of biomaterials in wet environments. A key advantage of our designed platform is the use of graphene as the optical window that interfaces wet and dry environments in the liquid cell. By combining near-field optical microscopy and synchrotron infrared radiation, we measure nanoscale fingerprint IR absorbance of a variety of liquids often used in biological studies. Further, we demonstrate the feasibility of the platform for the chemical analysis of protein clusters immersed in water with a clear view of the proteins secondary structure signatures. The simplicity of the proposed platform combined to the high quality of our data make our findings a template for future microfluidic devices targeting dynamical nanoscale-resolved chemical analysis.
关键词： nanoscale chemical analysis,biomaterials,synchrotron infrared nanospectroscopy,graphene chip,liquid cell
更新于2025-09-11 14:15:04
-
Raman, Infrared, and Chemical Characterization of Fly Ash-Generated Spherules
摘要： The majority of studies on silicate glass spherules containing fly ash deal only with the determination of their chemical composition. Nearly 70 vol.% of fly ash is comprised of silicate glass spherules. Here, we report spectroscopic properties of silicate glass spherules using the laser micro-Raman and Fourier transform infrared techniques coupled with refractive index measurements, X-ray diffraction, and electron probe micro-analysis to better ascertain their physical and chemical properties. Glass spherules show similar refractive indices (1.499–1.510) and a bell-shaped diffraction pattern with 5–10 vol.% of crystallites observed on microscopic and submicroscopic scales. The bulk chemical composition of fly ash spherules is predominantly silica-rich (SiO2: 70.96–74.13 wt.%) with a subordinate amount of Al2O3 (0.11–0.69 wt.%), FeO(Total) + MgO (3.6–4.94 wt.%), and CaO + Na2O + K2O (20.83–22.62 wt.%). The infrared spectra suggest the presence of a dissolved –OH– bearing fluid phase in the studied fly ash spherules. The spectra also show symmetric stretching peaks of C–O–C due to the atmospheric CO2 adsorption at 2350 cm–1. The Raman spectra show broad amorphous and/or short-ordered phases.
关键词： fly ash,micro-chemical analysis,Raman and infrared spectroscopy,silicate glass spherules
更新于2025-09-10 09:29:36
-
Potential use of nir and visible spectroscopy to analyze chemical properties of thermally treated wood
摘要： The modification of wood by thermal treatments produces characteristic changes in its chemical composition and surface color and can improve the structural and esthetic quality. The objective of this paper is to evaluate the potential of near infrared and visible spectroscopy to predict the modifications in chemical composition of Eucalyptys grandis and Pinus taeda after thermal treatment. Near infrared and visible spectra were collected directly on the longitudinal surface of wood samples. The thermally modified wood of both species showed higher content of lignin and extractives than the untreated wood. There was darkening of thermally modified wood, as a result of chemical modification caused by heat. The Near infrared/visible technique identified the groups that were modified by treatment. NIR and visible spectroscopy can be used to predict chemical composition of natural or thermally treated Eucalyptus grandis and Pinus taeda.
关键词： Eucalyptus grandis,Pinus taeda,wood composition,Chemical analysis,wood color,thermal modification
更新于2025-09-09 09:28:46
-
Preparation and Use of Chemically Modified Noble Metal Nanoparticles
摘要： Papers dealing with chemical modi? cation of the surface of noble metal nanoparticles and their use in analytical and bioanalytical chemistry, pharmacology, etc., are analyzed. Grafting of a layer of preset chemical composition on the nanoparticle surface allows preparation of functional materials combining the properties of the metal core (surface plasmon resonance, enhancement of ? uorescence and nonelastic scattering) and shell (selective interaction with components of the surrounding medium). Combination of these properties opens wide prospects for using the modi? ed nanoparticles in various branches of science and engineering, primary in chemical and biochemical analysis, and also in pharmacology.
关键词： functional materials,biochemical analysis,noble metal nanoparticles,chemical analysis,chemical modi? cation of the surface
更新于2025-09-04 15:30:14