Search results for "Principal component"
showing 10 items of 514 documents
A spectroscopic method for determining lignin content of softwood and hardwood kraft pulps
1998
Abstract A rapid method for determining the kappa number of unbleached and oxygen-delignified kraft pulps in the range 3–35 is presented. This novel method was based on the multivariate analysis of VIS spectral data on pulp samples. The calculated models and the test results indicated that partial least squares (PLS) and principal component regression (PCR) models yielded similar results, PLS being slightly more accurate. It was also found that for practical purposes a separate model for each wood feedstock and delignification process is needed.
FTIR Monitoring of Chemical Changes in Softwood During Heating
2000
Abstract A multivariate chemometric method for monitoring the mass loss of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) by IR spectroscopic determination of chemical changes occurring during the heat treatment (160 - 260 °C, 2 - 8 h) of these wood materials was developed. The method was based on the handling of FTIR data on treated and untreated wood powder samples by the partial least squares (PLS) method. In addition, unknown samples (treated and untreated pine and spruce) were classified into separate groups by the principal component analysis (PCA) method. The chemical changes occurring in the wood samples during heating were also briefly discussed.
Optimization criteria in sample selection step of local regression for quantitative analysis of large soil NIRS database
2012
International audience; Large soil spectral libraries compiling thousands of NIR (Near Infrared) reflectance spectra have been created encompassing a wide diversity and heterogeneity of spectra. Among the many chemometric approaches to the calibration of chemical and physical properties from these large libraries, local calibrations have the advantage of being able to select the most similar spectra to the spectrum of a target sample. This is particularly relevant when dealing with highly heterogeneous media such as soils, where the mineral matrix has a strong influence on spectral features. A crucial step in the implementation of local calibration procedures is the construction of local ne…
Sampling strategy in molecular microbial ecology: influence of soil sample size on DNA fingerprinting analysis of fungal and bacterial communities.
2003
Assessing soil microbial community structure by the use of molecular techniques requires a satisfactory sampling strategy that takes into account the high microbial diversity and the heterogeneous distribution of microorganisms in the soil matrix. The influence of the sample size of three different soil types (sand, silt and clay soils) on the DNA yield and analysis of bacterial and fungal community structure were investigated. Six sample sizes from 0.125 g to 4 g were evaluated. The genetic community structure was assessed by automated ribosomal intergenic spacer analysis (A-RISA fingerprint). Variations between bacterial (B-ARISA) and fungal (F-ARISA) community structure were quantified b…
The evolutionary history of the Arabidopsis arenosa complex: diverse tetraploids mask the Western Carpathian center of species and genetic diversity.
2012
The Arabidopsis arenosa complex is closely related to the model plant Arabidopsis thaliana. Species and subspecies in the complex are mainly biennial, predominantly outcrossing, herbaceous, and with a distribution range covering most parts of latitudes and the eastern reaches of Europe. In this study we present the first comprehensive evolutionary history of the A. arenosa species complex, covering its natural range, by using chromosome counts, nuclear AFLP data, and a maternally inherited marker from the chloroplast genome [trnL intron (trnL) and trnL/F intergenic spacer (trnL/F-IGS) of tRNA(Leu) and tRNA(Phe), respectively]. We unravel the broad-scale cytogeographic and phylogeographic pa…
Wing morphometrics as a possible tool for the diagnosis of the Ceratitis fasciventris, C. anonae, C. rosa complex (Diptera, Tephritidae)
2015
Abstract Previous attempts to resolve the Ceratitis FAR complex (Ceratitis fasciventris, Ceratitis anonae, Ceratitis rosa, Diptera, Tephritidae) showed contrasting results and revealed the occurrence of five microsatellite genotypic clusters (A, F1, F2, R1, R2). In this paper we explore the potential of wing morphometrics for the diagnosis of FAR morphospecies and genotypic clusters. We considered a set of 227 specimens previously morphologically identified and genotyped at 16 microsatellite loci. Seventeen wing landmarks and 6 wing band areas were used for morphometric analyses. Permutational multivariate analysis of variance detected significant differences both across morphospecies and g…
Rapid and Nondestructive Determination of Egg Freshness Category and Marked Date of Lay using Spectral Fingerprint
2020
The potential of nondestructive prediction of egg freshness based on near-infrared (NIR) spectra fingerprints would be beneficial to quality control officers and consumers alike. In this study, handheld NIR spectrometer in the range of 740 nm to 1070 nm and chemometrics were used to simultaneously determine egg freshness based on marked date of lay for eggs stored under cold and ambient conditions. The spectra acquired from the eggs were preprocessed using multiplicative scatter correction and principal component analysis (MSC-PCA). Linear discriminant analysis (LDA) was used to build identification model to predict the category of freshness, while partial least square regression (PLS-R) wa…
Metabolomics analysis and biological investigation of three Malvaceae plants
2019
Introduction: Metabolomics is a fast growing technology that has effectively contributed to many plant-related sciences and drug discovery. Objective: To use the non-targeted metabolomics approach to investigate the chemical profiles of three Malvaceae plants, namely Hibiscus mutabilis L. (Changing rose), H. schizopetalus (Dyer) Hook.f. (Coral Hibiscus), and Malvaviscus arboreus Cav. (Sleeping Hibiscus), along with evaluating their antioxidant and anti-infective potential. Methodology: Metabolic profiling was carried out using liquid chromatography coupled with high-resolution electrospray ionisation mass spectrometry (LC-HR-ESI-MS) for dereplication purposes. The chemical composition of th…
Rapid determination of baicalin and total baicalein content in Scutellariae radix by ATR-IR and NIR spectroscopy
2013
In this study methods for the quantification of baicalin and total baicalein in Scutellariae radix with near infrared (NIR) spectroscopy and attenuated-total-reflectance mid-infrared (ATR-IR) spectroscopy in hyphenation with multivariate analysis were developed and compared. The reference analysis was performed by high performance liquid chromatography coupled to diode array detection (HPLC-DAD). Different pretreatments like standard normal variate (SNV), multiplicative scatter correction (MSC), first and second derivative Savitzky-Golay were applied on the spectra to optimize the calibrations. A principal component analysis was performed with both spectroscopic methods to distinguish wild …
Growth in Average Firm Size of U.S. Industrial Portfolios and the Cross-Section of Expected Returns
2018
This paper shows that growth in average firm size in U.S. industrial portfolios predicts future growth in average firm size. Moreover, the payoffs of industrial portfolios sorted by growth in average firm size in the previous period increase linearly as we move from lowest to highest growth in average firm size. The spread between highest and lowest growth in average firm size is economically large and cannot be explained by exposures to standard risk factors or the asset growth effect (Cooper, Gulen, and Schill, 2008). Principal component analysis reveals that this growth in average firm size effect is linked to the first principal component. Moreover, stochastic discount factor model anal…