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An Approach for In Situ Rapid Detection of Deep-Sea Aromatic Amino Acids Using Laser-Induced Fluorescence
摘要： Amino acids are the material basis of almost all life activities. An improved understanding of the source, state, and cycle of amino acids is essential for determining the energy flow and material circulation of marine ecosystems. In the present study, an in situ rapid detection method of ultraviolet (UV; 266 nm) laser-induced fluorescence (LIF) technology was used to detect three natural, aromatic amino acids in the seawater. The laser-induced fluorescence peaks of aromatic amino acids tryptophan, tyrosine, and phenylalanine were located at 350 nm, 300 nm, and 280 nm, respectively. High, linear correlations between the concentrations of the aromatic amino acids and the fluorescence peak heights were observed, and the lowest detectable concentrations of tryptophan, tyrosine, and phenylalanine were 4.70 × 10?9 mol/L, 2.76 × 10?8 mol/L, and 6.05 × 10?7 mol/L, respectively, which allowed us to quantify their concentrations by using laser-induced fluorescence. This paper not only provides a practical method for the detection of aromatic amino acids in seawater, but a new means to further understand the biogeochemical processes of carbon cycles in the deep sea.
关键词： in situ detection,soluble aromatic amino acid,laser-induced fluorescence
更新于2025-09-16 10:30:52
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Investigation of excitation interference in laser-induced breakdown spectroscopy assisted with laser-induced fluorescence for chromium determination in low-alloy steels
摘要： Chromium determination in steels suffered from excitation interference in laser-induced breakdown spectroscopy assisted with laser-induced fluorescence (LIBS-LIF). In this work, excitation interference between target chromium atoms and matrix iron atoms was investigated in detail. Relative absorption strength (RAS) of chromium and iron was mathematically deduced and utilized to estimate the excitation interference theoretically. Standard calibration curves of LIBS and LIBS-LIF for chromium determination in low-alloy steels were experimentally established. The chromium line 359.35 nm with less interference in the RAS map provided better analytical performance (slope of 1.99 ×10 5 counts/ wt%, detection limit of 8.64 μg g ? 1 , R 2 of 0.992, average RSD of 2.89%), in accordance with the theoretical estimation. This work realized sensitive and accurate determination of trace chromium in low-alloy steels, even influenced by excitation interference. An effective estimation method was provided for evaluating excitation interference to choose a suitable excitation line.
关键词： Laser-induced fluorescence,Steel,Excitation interference,Chromium,Laser-induced breakdown spectroscopy
更新于2025-09-12 10:27:22
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Revealing Long-Range Substituent Effects in the Laser-Induced Fluorescence and Dispersed Fluorescence Spectra of Jet-Cooled CH <sub/><i>x</i> </sub> F <sub/> 3– <i>x</i> </sub> CH <sub/>2</sub> O ( <i>x</i> = 1, 2, 3) Radicals
摘要： The B?←X? laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectra of the atmospherically important β-monofluoro ethoxy (MFEO), β,β-difluoro ethoxy (DFEO), and β,β,β-trifluoro ethoxy (TFEO) radicals were recorded with vibronic resolution under jet-cooled conditions. To simulate the spectra, Franck-Condon factors were obtained from quantum chemical computations carried out at the CAM-B3LYP/6-311++G(d,p) level of theory. The simulations reproduce well both the LIF and DF spectra. Both conformers (G and T) of MFEO and one (G) of the two conformers of DFEO contribute to the LIF spectrum. A comparison between the experimental and calculated spectra confirms the expected long-range field effects of the CHxF3?x group on electronic transition energies and bond strengths, especially in the excited electronic (B?) state. Although TFEO has only one conformer, its LIF spectrum is highly congested, which is attributed to the interaction between CO stretch and the ?CF3 internal rotation.
关键词： Laser-Induced Fluorescence,Molecular Structure,Spectroscopy,Quantum Chemistry,Fluoroethoxy Radicals,Jet-cooled,Dispersed Fluorescence
更新于2025-09-12 10:27:22
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Correcting the effect of the detection angular on laser-induced chlorophyll fluorescence
摘要： Chlorophyll fluorescence has been widely used to monitor vegetation growth status and quantitative remote sensing monitoring of vegetation biochemical content. Therefore, it is significant to accurately measure the fluorescence information. In this study, the variation in fluorescence intensity of vivo vegetation leaf with the change in detection angle on the basis of laser-induced fluorescence technology was discussed. Experimental results demonstrated that the relationship between the emission fluorescence intensity and detection angles could be explained by the cosine expression. Then, two-step fluorescence intensity correction method was proposed. Firstly, the fluorescence intensity was corrected based on the changing of cosine expression. Secondly, the fluorescence ratio calculated based on the corrected fluorescence intensity. Results demonstrated that the effect of detection angles on fluorescence signals can be efficiently eliminated compared to the traditional spectral ratio method. Findings of this study may be valuable in promoting the applications of laser-induced fluorescence in remote sensing to achieve accurate chlorophyll fluorescence information for quantitative monitoring of plant nutrient stress.
关键词： fluorescence ratios,intensity correction,angular distribution,Laser-induced fluorescence
更新于2025-09-12 10:27:22
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Comparative laser-induced fluorescence evolution analysis of different oil pollution on the terrestrial surface
摘要： We have studied the time evolution of the laser-induced fluorescence spectra of oil pollution on the terrestrial surface at a fluorescence excitation wavelength of 355 nm. The paper presents a block-diagram of the experimental laboratory setup and data processing results of the laser-induced fluorescence spectra for the oil-polluted soil and sand and conducts a comparative analysis of the fluorescence spectra evolution of pollution due to spilling crude oil and heavy and light petroleum products.
关键词： petroleum products,laser-induced fluorescence,terrestrial surface,oil pollution
更新于2025-09-12 10:27:22
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Deep UV laser-induced fluorescence for pharmaceutical cleaning validation
摘要： Cleaning verification and validation is a requirement in the pharmaceutical industry. Due to the limited number of mobile devices that do effective and accurate onsite cleaning verification, it is mostly done via lab-based quality control techniques. These techniques, such as High-Performance Liquid Chromatography (HPLC) or Total Organic Carbon, often lead to extending the validation of cleaning by days. The void of more sensitive, accurate, and portable instruments to verify cleaning onsite has to be filled. The article discusses the use of Deep Ultra Violet (DUV) laser-induced fluorescence for detecting carryover of Active Pharmaceutical Ingredients (APIs) and detergents onsite. A modified spectrometer was used as an offsite bench type prototype for analyzing trace samples of API and cleaning detergents with various substrates. Even if the API to be detected has a low fluorescence efficiency, the specificity of the technique allows API traces having concentrations as low as ≈0.20 μg/cm2 to be identified. The work also shows the possibility of using a probe for validating cleaning of hard to reach areas using DUV laser-induced fluorescence. DUV laser-induced fluorescence of trace API over any polymer/glass substrate has better Signal to Background Ratio (SBR) compared to FTIR absorption techniques. Processing times of DUV laser-induced fluorescence trace detection are shown to be much less than swab based methods.
关键词： Active Pharmaceutical Ingredients (APIs),pharmaceutical cleaning validation,Deep Ultra Violet (DUV),signal to background ratio (SBR),laser-induced fluorescence
更新于2025-09-12 10:27:22
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The far-field plasma characterization in a 600 W Hall thruster plume by laser-induced fluorescence
摘要： Non-intrusive characterization of the singly ionized xenon velocity in Hall thruster plume using laser induced fluorescence (LIF) is critical for constructing a complete picture of plume plasma, deeply understanding the ion dynamics in the plume, and providing validation data for numerical simulation. This work presents LIF measurements of singly ionized xenon axial velocity on a grid ranging from 100 mm to 300 mm in axial direction and from 0 mm to 50 mm in radial direction for a 600 W Hall thruster operating at the nominal condition of discharge voltage 300 V and discharge current 2 A, the influence of discharge voltage is investigated as well. The ion velocity distribution function (IVDF) results in the far-field plume demonstrate a profile of bimodal IVDFs, especially prominent at radial distances greater than channel inner radius of 22 mm at axial position of 100 mm, which is quite different from that of the near-field plume where bimodal IVDFs occur in the central core region for the same power Hall thruster when compared to previous LIF measurements of BHT-600 by Hargus W A (2010, Journal of Propulsion and Power, 26 135). Beyond 100 mm, only single-peak IVDFs are measured. The two-dimensional ion velocity vector field indicates the bimodal axial IVDF is merely a geometry effect for the annular discharge channel in the far-field plume. Results about the IVDF, the most probable velocity and the accelerating potential profile along the centerline all indicate that ions are still accelerating at axial distances greater than 100 mm, and the maximum most probable velocity measured at 300 mm downstream of the exit plane is about 19 km/s. In addition, the most probable velocity of ions along radial direction changes a little except the lower velocity ion populations in the bimodal IVDF cases. The ion temperature at axial distances of 100 mm and 300 mm oscillates along the radial direction, while the ion temperature first increases, and then decreases for the 200 mm case. Finally, the axial position for the ion peak axial velocity on the thruster centerline is shifted upstream for higher discharge voltages, and the velocity curve is becoming steeper with the discharge voltage before reaching the maximum. This observation can be used as a criterion to optimize the thruster performance.
关键词： optical diagnostic,laser-induced fluorescence,Hall thruster,ion velocity distribution function
更新于2025-09-12 10:27:22
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Capillary Electrophoresis with Laser Induced Fluorescence Detection for Study of the Association of HSP60 Gene Polymorphism with Gouty Arthritis
摘要： Background: Gout arthritis is a common inflammatory arthritis and it poses a major threat to human health. Objective: A method of capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) for the detection of HSP60 gene polymorphism has been developed and applied to the exploration of correlation between gouty arthritis and HSP60 gene polymorphism. Methods: The genomic deoxyribonucleic acid from 59 patients with gouty arthritis and 64 control subjects was extracted and the conservative fragment of HSP60 was amplified. The products were digested with restriction endonuclease NlaIII and then separated and detected by the proposed method. Results: In the case group, there were 7 cases of TT genotype, 29 cases of CC genotype, and 23 cases of CT genotype. In the control group, there were 4 cases of TT genotype, 6 cases of CC genotype, and 54 cases of CT genotype. The detection results of the samples were statistically analyzed by binary logistic regression and Spearman correlation analysis. After adjusting gender, age, and other compounding factors, the TT genotype and CT genotype of the HSP60 gene were found to affect gouty arthritis. Conclusions: When used for gene polymorphism research, the proposed CE-LIF method has the advantages of high efficiency, rapidity, sensitivity, and low sample consumption. A moderate correlation between gouty arthritis and HSP60 genotype distribution was discovered for the first time. Highlights: A new method using CE-LIF for the detection of HSP60 gene polymorphism of 59 patients with gouty arthritis and 64 control subjects in China. The correlation between gouty arthritis and HSP60 gene polymorphism was explored for the first time.
关键词： Gouty arthritis,Capillary electrophoresis,HSP60 gene polymorphism,Laser-induced fluorescence
更新于2025-09-12 10:27:22
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Laser-Induced Fluorescence and Dispersed Fluorescence Spectroscopy of Jet-Cooled Isopentoxy Radicals
摘要： The B?-X? laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectra of jet-cooled isopentoxy radicals have been obtained. The LIF spectrum of isopentoxy lacks strong transitions to the CO-stretch levels that are typical for alkoxy radicals. Instead, it contains two low-frequency vibrational progressions due to large-amplitude motions of the GG’ and GG conformers involving torsion of the C1C2C3H dihedral angle. Other vibronic bands observed in the LIF spectrum are attributed to the TG conformer. Molecular carriers of the vibronic transitions in the LIF spectrum are identified by comparing the experimentally obtained spectrum and the simulated one. DF spectra of the GG and TG conformers are dominated by strong vibrational progressions of the CO-stretch mode when the origin or the CO-stretch band is pumped. When non-CO-stretch bands are pumped, the DF spectra are dominated by combination bands of the CO-stretch and the pumped mode. ?-X? separations of the GG, and TG conformers were also determined from the DF spectra.
关键词： Isopentoxy Radicals,Conformers,Laser-Induced Fluorescence,Vibrational Progressions,Jet-Cooled,Dispersed Fluorescence Spectroscopy
更新于2025-09-11 14:15:04
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Understanding and Interpreting Laser Diagnostics in Flames: A Review of Experimental Measurement Techniques
摘要： There is a wealth of existing experimental data of flames collected using laser diagnostics. The primary objective of this review is to provide context and guidance in interpreting these laser diagnostic data. This educational piece is intended to benefit those new to laser diagnostics or with specialization in other facets of combustion science, such as computational modeling. This review focuses on laser-diagnostics in the context of the commonly used canonical jet-in-hot-coflow (JHC) burner, although the content is applicable to a wide variety of configurations including, but not restricted to, simple jet, bluff body, swirling and stratified flames. The JHC burner configuration has been used for fundamental studies of moderate or intense low oxygen dilution (MILD) combustion, autoignition and flame stabilization in hot environments. These environments emulate sequential combustion or exhaust gas recirculation. The JHC configuration has been applied in several burners for parametric studies of MILD combustion, flame reaction zone structure, behavior of fuels covering a significant range of chemical complexity, and the collection of data for numerical model validation. Studies of unconfined JHC burners using gaseous fuels have employed point-based Rayleigh-Raman or two-dimensional Rayleigh scattering measurements for the temperature field. While the former also provides simultaneous measurements of major species concentrations, the latter has often been used in conjunction with planar laser-induced fluorescence (PLIF) to simultaneously provide quantitative or qualitative measurements of radical and intermediary species. These established scattering-based thermography techniques are not, however, effective in droplet or particle laden flows, or in confined burners with significant background scattering. Techniques including coherent anti-Stokes Raman scattering (CARS) and non-linear excitation regime two-line atomic fluorescence (NTLAF) have, however, been successfully demonstrated in both sooting and spray flames. This review gives an overview of diagnostics techniques undertaken in canonical burners, with the intention of providing an introduction to laser-based measurements in combustion. The efficacy, applicability and accuracy of the experimental techniques are also discussed, with examples from studies of flames in JHC burners. Finally, current and future directions for studies of flames using the JHC configuration including spray flames and studies and elevated pressures are summarized.
关键词： moderate or intense low oxygen dilution (MILD) combustion,autoignition,vitiated coflow burner (VCB),laser-induced fluorescence (LIF),thermography,jet in hot coflow (JHC),planar laser diagnostics
更新于2025-09-11 14:15:04