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Quantitative analysis on <i>in vivo</i> tumor-microvascular images from optical-resolution photoacoustic microscopy
摘要： Optical-resolution photoacoustic microscopy (OR-PAM) has been shown to be an excellent imaging modality for monitoring and study of tumor microvasculature. However, previous studies focused mainly on the normal tissues and did not quantify the tumor microvasculature. In this study, we present an in vivo OR-PAM imaging of the melanomas and hepatoma implanted in the mouse ear. We quantify the vessel growth by extracting the skeletons of both dense and thin branches of the tumor microvasculature obtained by Hessian matrix enhancement followed by improved two-step multistencils fast marching method. Compared to the previous methods of using OR-PAM for normal tissues, our method was more effective in extracting the binary vascular network in the tumor images and in obtaining the complete and continuous microvascular skeleton maps. Our demonstration of using OR-PAM in improving microvasculature of tumors and quantification of tumor growth would push deep this technology for the early diagnosis and treatment of cancers.
关键词： photoacoustic imaging,tumor neovascular network,quantitative analysis,optical-resolution photoacoustic microscopy
更新于2025-09-19 17:15:36
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Improved measurement on quantitative analysis of coal properties using laser induced breakdown spectroscopy
摘要： It is of great significance to realize the rapid or online analysis of coal properties for combustion optimization of thermal power plants. In this work, a set of calibration schemes based on laser-induced breakdown spectroscopy (LIBS) was determined to improve the measurement on quantitative analysis of coal properties, including proximate analysis (calorific value, ash, volatile content) and ultimate analysis (carbon and hydrogen). Firstly, different normalization methods (channel normalization and normalization with the whole spectral area) combined with two regression algorithms (partial least-squares regression [PLSR] and support vector regression [SVR]) were compared to initially select the appropriate calibration method for each indicator. Then, the influence of de-noising by the wavelet threshold de-noising (WTD) on quantitative analysis was further studied, thereby the final analysis schemes for each indicator were determined. The results showed that WTD coupled SVR can be well estimated calorific value and ash, the root mean square error of prediction (RMSEP) were 0.80 MJ kg?1 and 0.60%. Coupling WTD and PLSR performed best for the measurement of volatile content, the RMSEP was 0.76%. For the quantitative analysis of carbon and hydrogen, normalization with the whole spectral area combined with SVR can get better measurement results, the RMSEP of the measurements were 1.08% and 0.21%, respectively. The corresponding average standard deviation (RSD) for calorific value, ash, volatile content, carbon and hydrogen of validation sets were 0.26 MJ kg?1, 0.57%, 0.79%, 0.47% and 0.08%, respectively. The results demonstrated that the selection of appropriate spectral pre-processing coupled with calibration strategies for each indicator can effectively improve the accuracy and precision of the measurement on coal properties.
关键词： partial least-squares regression (PLSR),quantitative analysis,normalization,Laser-induced breakdown spectroscopy (LIBS),coal properties,support vector regression (SVR),wavelet threshold de-noising (WTD)
更新于2025-09-19 17:13:59
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Quantitative analysis of Pb in soil by femtosecond-nanosecond double-pulse laser-induced breakdown spectroscopy
摘要： The effects of inter-pulse delay on the quantitative analysis of femtosecond-nanosecond double-pulsed laser-induced breakdown spectroscopy (fs-ns DP-LIBS) for assessing Pb in soil have been systematically studied in this work. A femtosecond pulse laser was focused to produce a filament, which was used to ablate the soil sample and produce an appreciable amount of aerosol particles ejected from the soil surface at a low density. Scattering images of the soil particles ejected from the soil surface were obtained, and the soil particles were found to have a delay of 800 μs. After an inter-pulse delay, a nanosecond Nd:YAG laser re-ablated the soil particles and obtained a spectral enhancement and a narrow line width. The quantitative analysis based on DP-LIBS for Pb in soil was strongly dependent on the inter-pulse delay time. With an inter-pulse delay time of 10 μs for DP-LIBS, the R-square factor (R2), relative standard deviation (RSD), root mean square error of cross-validation (RMSECV), and limit of detection (LOD) were 99.42%, 2.99%, 0.42 wt.%, and 8.13 mg/kg, respectively. These findings demonstrate that DP-LIBS can be applied as an efficient spectroscopic tool to improve the quantitative analysis of Pb heavy metal in soil.
关键词： fs-ns DP-LIBS,quantitative analysis,limit of detection,Pb heavy metal
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Quantitative Analysis of Heavy Metal Components in Soil by Laser-Induced Breakdown Spectroscopy Based on Principal Component Analysis
摘要： The calibration curves of heavy metal elements Cd and Ni were established based on laser induced breakdown spectroscopy of standard soil and soil to be tested. The plasma excitation test was carried out on the soil by laser induced breakdown spectroscopy to obtain a plasma spectrum with a wavelength of 300-1000 nm. By comparing the characteristic peaks in the obtained spectrum with the National Institute of Standards and Technology database, it is found that the test samples contain heavy metal elements such as Cd, Cr, Cu, Hg, Ni and W, and the Cd and the measured standard soil. The main method analysis of the peak of Ni element is carried out, and the principal component regression model is established to obtain the calibration curve of Cd and Ni elements, and then the content of Cd and Ni elements in the soil to be tested is estimated. Based on the concentration of the national standard soil sample and the measured spectral intensity, the linear correlation coefficients between the predicted and actual values of the Cd and Ni element contents were established to be 1 and 0.99443. Compared with the commonly used methods, laser-induced breakdown spectroscopy can quickly detect samples to be tested, and sample pretreatment is simple and less damage to the sample.
关键词： Principal component analysis,Soil heavy metal pollution,Laser induced breakdown spectroscopy,Qualitative and quantitative analysis
更新于2025-09-16 10:30:52
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A feature selection method combined with ridge regression and recursive feature elimination in quantitative analysis of laser induced breakdown spectroscopy
摘要： In the spectral analysis of laser-induced breakdown spectroscopy, abundant characteristic spectral lines and severe interference information exist simultaneously in the original spectral data. Here, a feature selection method called recursive feature elimination based on ridge regression (Ridge-RFE) for the original spectral data is recommended to make full use of the valid information of spectra. In the Ridge-RFE method, the absolute value of the ridge regression coefficient is used as a criterion to screen spectral characteristic, the feature with the absolute value of minimum weight in the input subset features was removed by recursive feature elimination (RFE), and the selected features were used as inputs of the partial least squares regression (PLS) model. The Ridge-RFE method based PLS model was used to measure the Fe, Si, Mg, Cu, Zn and Mn for 51 aluminum alloy samples, and the results showed that the root mean square error of prediction (RMSEP) decreased greatly compared to the PLS model with full spectrum as input. The overall results demonstrate that the Ridge-RFE method is more efficient to improve model generalization ability.
关键词： recursive feature elimination,laser-induced breakdown spectroscopy,quantitative analysis,ridge regression,feature selection
更新于2025-09-16 10:30:52
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Quantitative Analysis of Twelve Active Components Combined With Chromatographic Fingerprint for Comprehensive Evaluation of Qinma Prescription by Ultra-Performance Liquid Chromatography Coupled With Diode Array Detection
摘要： A combination method of ultra-performance liquid chromatography (UPLC) coupled with diode array detection has been developed for quality evaluation of Qinma prescription (QMP), based on chromatographic fingerprint technology with the similarity analysis (SA) and the quantitative analysis of 12 components by hierarchical cluster analysis (HCA). The established method has been validated by linearity, precision, repeatability, stability and recovery tests. The UPLC fingerprints with 17 common peaks of 5 QMP samples prepared by different extraction methods including water decoction extraction, water extraction-ethanol precipitation method, ethanol reflux extraction, ethanol extraction-water precipitation method and methanol ultrasonic extraction were obtained, and the SA results indicated that similarity index was greatly influenced by the large peak. The similarity index ranged from 0.816 to 0.999 basing on 17 peaks, which has been decreased to 0.683–0.999 basing on 16 peaks without the large peak of baicalin (BA). The results of simultaneous quantification of 12 components in these 5 QMP samples proved that BA, gallic acid (GA), wogonoside (WOG) and gentiopicroside (GEN) were the major ingredients in QMP with high contents >1.44 (mg/g), indicating that ethanol reflux was the most effective extraction method. Integrating fingerprint analysis, simultaneous determination and HCA, the established method is rapid, sensitive, accurate and readily applicable. All the results indicated that the combination method can control the quality of QMP and its related traditional Chinese medicinal compounds more comprehensively and scientifically.
关键词： quantitative analysis,Qinma prescription,similarity analysis,diode array detection,UPLC,hierarchical cluster analysis,chromatographic fingerprint
更新于2025-09-12 10:27:22
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Fluorometric lateral flow immunoassay for simultaneous determination of three mycotoxins (aflatoxin B1, zearalenone and deoxynivalenol) using quantum dot microbeads
摘要： A fluorometric lateral flow immunoassay (LFA) is described for the simultaneous determination of the mycotoxins aflatoxin B1 (AFB1), zearalenone (ZEN) and deoxynivalenol (DON). The method is based on the use of CdSe/SiO2 quantum dot microbeads (QBs) with a mean diameter of 106 nm. These have strong red luminescence (with excitation/emission peaks at 365/622 nm) which results in enhanced sensitivity. The QBs binding with monoclonal antibodies (mAbs) as the signal probes can react specifically with AFB1, ZEN and DON, respectively. There is an inverse correlation between the fluorescence signal intensity of test line and the analyte content, which can realize the quantitative analysis of analytes within 15 min. The limits of detection in solution are 10, 80 and 500 pg mL?1 for AFB1, ZEN and DON, respectively. Besides, the average recoveries from spiked feed range from 85.5 to 119.0%, and the relative standard deviations are less than 16.4% for both intra- and inter-day assays. The method was used to analyze naturally contaminated feedstuff, and this resulted in a good agreement with data obtained by LC-MS/MS.
关键词： Rapid detection,LC-MS/MS,Food safety,Multiplexed,Immunochromatographic strip,Quantitative analysis,Cereal samples,Antibody,Feedstuff
更新于2025-09-12 10:27:22
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Fourier transform infrared imaging and quantitative analysis of pre-treated wood fibers: A comparison between partial least squares and multivariate curve resolution with alternating least squares methods in a case study
摘要： Pretreated lignocellulosic fibers were used as a case study to compare two chemometric methods for the quantification of chemical components in Fourier transformed infrared (FT-IR) images. Partial least squares (PLS) and multivariate curve resolution with alternating least squares (MCR-ALS) methods were applied to the images to quantify glucans, lignin and hemicellulose content. The main problem for calibration in samples from natural origin is to obtain proper reference material for pixel to pixel quantification. Furthermore, chemical components in wood experience changes after different pretreatment conditions; therefore commercially available reference material may not have the same identity of the components present in the sample. Concentration information of bulk samples obtained by wet chemistry methods, along with the median spectrum of whole images, was used as an alternative for PLS calibration in this scenario. Results show that both methods provided similar spatial distribution for lignin and hemicellulose in the concentration maps, but image reconstruction of glucans shows differences in distribution between the two methods. PLS models used to quantify pixels in an image were previously validated through the prediction of global concentration of samples, using the median spectrum of different images (RMSEP ? 1.3% for glucans, 1.0% for lignin and 0.9% for hemicelluloses); The range of pixel concentration predicted in a single image was too narrow possibly due to the lack of a calibration set with a wider dynamic range. Concentration maps obtained with MCR-ALS were satisfactory and the range of concentration for pixels was more consistent with what would be expected. A quantification approach that does not need a calibration set was used to transform concentration profiles into real concentration units for pixels. Therefore MCR-ALS was a more suitable method for quantification in this specific case study.
关键词： PLS,Lignocellulosic fibers,Hyperspectral imaging,Quantitative analysis,MCR-ALS
更新于2025-09-12 10:27:22
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Quantitative analysis of cadmium and zinc in algae using laser-induced breakdown spectroscopy
摘要： In the demand for renewable energy sources, algae are considered to have a good potential for biodiesel production. Fast detection of heavy metals in energetic algae is of vital importance for algal biomass and biodiesel production environment monitoring. This study aims to determine cadmium (Cd) and zinc (Zn) contents in algal pellets with laser-induced breakdown spectroscopy (LIBS) technology. Partial least squares (PLS) regression and extreme learning machine (ELM) were constructed after spectral preprocessing by standard normal variate transformation (SNV), multiplicative scatter correction (MSC) and Savitzky–Golay smoothing (SG). For univariate analysis, ELM models based on Cd II 226.45 nm and Zn II 206.19 nm of SNV preprocessed spectra achieved the best results for Cd and Zn content prediction respectively, with Rp, RMSEP and RPD values of 0.9866, 50.71 mg kg?1 and 6.95 for the former, and 0.9873, 30.08 mg kg?1 and 6.44 for the latter. Multivariate analysis of Cd based on the PLS model with global spectra achieved the best performance with Rc and Rp values of 0.9965 and 0.9972, RMSECV and RMSEP values of 25.57 mg kg?1 and 23.63 mg kg?1, and an RPD value as high as 13.27, showing the excellent robustness and effectiveness of the model for Cd detection. For Zn analysis, the best performance was achieved by the ELM model based on feature variables selected by regression coefficients, with Rc and Rp values of 0.9836 and 0.9920, RMSEC and RMSEP values of 34.25 mg kg?1 and 24.64 mg kg?1, and an RPD value of 7.87. The results indicated that the LIBS technique combined with appropriate preprocessing algorithms and multivariate chemometric methods could be a rapid and accurate way for quantitative analysis of Cd and Zn contents in algae and the aquatic environment.
关键词： laser-induced breakdown spectroscopy,quantitative analysis,chemometric methods,zinc,algae,cadmium
更新于2025-09-12 10:27:22
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Fast analysis of caffeinated beverages using laser diode thermal desorption mass spectrometry (LDTD-MS/MS)
摘要： A rapid method for quantitative caffeine analysis in carbonated and non-carbonated beverages and liquid dietary supplement products was developed based on the direct sample introduction technique of laser diode thermal desorption atmospheric pressure chemical ionisation with tandem mass spectrometry (LDTD-MS/MS). Product samples were diluted with a mixture of methanol, water, and d3-caffeine internal standard. Sample aliquots were filtered, spotted on a metal-lined LDTD microtitre plate, dried, and thermally desorbed for subsequent ionisation and analysis by MS/MS analysis. Each sample required a 6 s desorption, and sample-to-sample analysis time of less than 30 s per sample. Caffeine yielded a linear calibration curve over the range 0.5–100 μg mL?1 (R2 > 0.995). Caffeine recoveries from fortified samples ranged from 97% to 107% with <5% RSD. The caffeine determination was not affected by matrix interferences despite the large range of ingredients, vitamins, sweeteners, extracts, and additives present in the products tested, even though LDTD-MS/MS is a whole-sample desorption technique with no separation of matrix background. The method detection limit was below 0.12 μg mL?1. The method was applied to 33 caffeinated products and LDTD-MS/MS quantitative results closely correlated (R2 > 0.998) with the regulatory standard HPLC-UV method (AOAC Official Method 979.08).
关键词： quantitative analysis,direct analysis mass spectrometry,Caffeine,laser diode thermal desorption,energy drinks
更新于2025-09-11 14:15:04