Search results for "ear-infrared spectroscopy"
showing 10 items of 139 documents
Quantitative determination of surface area of silica gel particles by near infrared spectroscopy and chemometrics
2008
Abstract Surface areas of silica gel particles have been quantitatively determined by using near infrared spectrometry and chemometrics. Surface areas of six silica gel samples with varying surface area (300–750 m2/g) have been determined by the common Brunauer–Emmett–Teller (BET) method and used in preparing mixtures of silica gel samples with varying surface area in the ranges 300–474 and 500–750 m2/g. The near infrared spectra of the mixtures were measured and the spectral profiles calibrated against the calculated surface area of the mixtures as dependent variable using partial least squares (PLS) technique. The models obtained from the calibrations were then used in predicting the surf…
Fast authentication of tea tree oil through spectroscopy
2018
Two new procedures, based on infrared spectroscopy in the near infrared (NIR) and mid infrared (MIR), have been developed for the authentication of tea tree oil (TTO) commercial samples. Infrared measurements were made on untreated samples by transmission NIR and attenuated total reflectance (ATR) followed by partial least square discriminant analysis (PLS-DA). These methods offer a fast and low cost alternative to enantiomeric two-dimensional gas chromatography coupled to mass detection usually employed to discriminate between authentic and non-authentic samples. In these studies, a set of 267 samples, including authentic and non-authentic labelled tea tree oil samples, were used to build …
A Functional Near-Infrared Spectroscopy Examination of the Neural Correlates of Cognitive Shifting in Dimensional Change Card Sort Task
2020
This study aims to examine the neural correlates of cognitive shifting during the Dimensional Change Card Sort Task (DCCS) task with functional near-infrared spectroscopy. Altogether 49 children completed the DCCS tasks, and 25 children (Mage = 68.66, SD = 5.3) passing all items were classified into the Switch group. Twenty children (Mage = 62.05, SD = 8.13) committing more than one perseverative errors were grouped into the Perseverate group. The Switch group had Brodmann Area (BA) 9 and 10 activated in the pre-switch period and BA 6, 9, 10, 40, and 44 in the post-switch period. In contrast, the Perseverate group had BA 9 and 10 activated in the pre-switch period and BA 8, 9, 10 in the pos…
Segmentation of Hyperspectral Images for the Detection of Rotten Mandarins
2008
The detection of rotten citrus in packing lines is carried out manually under ultraviolet illumination, which is dangerous for workers. Light emitted by the rotten region of the fruit due to the ultraviolet-induced fluorescence is used by the operator to detect the damages. This procedure is required because the low contrast between the damaged and sound skin under visible illumination difficult their detection. We study a set of techniques aimed to detect rottenness in citrususing visible and near infrared lighting trough an hyperspectral imaging system. Methods for selecting a proper set of wavelengths are investigated such as correlation analysis, mutual information, stepwise or genetic …
MULTISPECTRAL VENOUS IMAGES ANALYSIS FOR OPTIMUM ILLUMINATION SELECTION
2013
International audience; Intravenous (IV) catheterization is the most important phase in medical practices of daily life. It is hard to localize veins in patients who have deep veins, minor age or dark skin; hence multiple attempts become indispensable for proper catheterization in such cases. Near Infrared (NIR) Imaging allow to visualize the veins underneath the skin of persons having non-visibility of veins problem. This paper reports the pre-selection of illuminants that ensure best veins/tissues contrast for patients having different skin tone. The sample subjects have been divided in four different classes based on the Luminance value of their skin tone in order to extract the best ill…
Flow injection near-infrared determination of ethanol in chloroform
1995
A simple and direct flow injection (FIA) procedure has been developed for the determination of the stabilizing agent ethanol in chloroform samples. The procedure is based on the use of the absorbance band of ethanol in the near-infrared (NIR) region at 2272 nm, measured in front of a reference sample of chloroform stabilized with amylene. The method developed provides a limit of detection of 0.0045% (v/v) and a dynamic range until 10% (v/v) with a typical variation coefficient of 0.4% for six independent analysis of a real sample containing approximately 1% (v/v) of ethanol. The sample injection frequency allowed by the method is 78 h−1.
Near infrared determination of Diuron in pesticide formulations
2005
Abstract A simple, fast and environmentally friendly near infrared (NIR)-based methodology was developed for Diuron determination in pesticide formulations. This methodology was based on the pesticide extraction with acetonitrile and subsequent transmittance measurement determination by peak area measurement between 2021 and 2047 nm, corrected with a single point baseline established at 2071 nm. The repeatability, as relative standard deviation of five independent analysis of a 15.3 mg g −1 Diuron standard was 0.03% and the limit of detection 0.013 mg g −1 . The reagent consumption was clearly reduced in front of a chromatographic reference procedure from 39.1 ml acetonitrile per sample, re…
Mid- and near-infrared determination of metribuzin in agrochemicals
2008
Abstract Two infrared-based methodologies were developed for metribuzin determination in pesticide formulations after extraction with acetonitrile. Fourier transform mid infrared (MIR) procedure was based on peak area measurements between 1692 and 1670 cm −1 corrected with a baseline fixed at 1877 cm −1 . Fourier transform near infrared (NIR) determination was made by measuring the peak area between 6498 and 6332 cm −1 corrected using a two points baseline defined between 6570 and 6212 cm −1 . Repeatability, as relative standard deviation, of 5 independent measurements at mg g −1 concentration level was 0.3% and 0.03% for MIR and NIR, respectively, and limit of detection values of 9 and 17 …
PLS-NIR determination of total sugar, glucose, fructose and sucrose in aqueous solutions of fruit juices
1997
Abstract An analytical procedure has been developed for the direct determination of sugars in fruit juice samples. The method is based on the partial least-squares (PLS) treatment of first derivative near infrared (NIR) spectroscopic data obtained between 1200 and 2450 nm, using 1 mm pathlength cell and a multicomponent calibration set, including seven binary mixtures and 10 ternary mixtures of glucose, fructose and sucrose. The limit of detection values found are of the order of 0.2 g/100 ml for total sugar and 0.2, 0.4 and 0.5 g/100 ml for glucose, fructose and sucrose, respectively. Relative standard deviation values obtained vary from 0.4% to 2.3% for six independent measurements of ind…
Contact and contactless diffuse reflectance spectroscopy: potential for recovery monitoring of vascular lesions after intense pulsed light treatment.
2011
Optical fiber contact probe diffuse reflectance spectroscopy and remote multispectral imaging methods in the spectral range of 400 to 1100 nm were used for skin vascular malformation assessment and recovery tracing after treatment by intense pulsed light. The results confirmed that oxy-hemoglobin relative changes and the optical density difference between lesion and healthy skin in the spectral region 500 to 600 nm may be successfully used for objective appraisal of the therapy effect. Color redness parameter a* = 2 is suggested as a diagnostic border to distinguish healthy skin and vascular lesions, and as the indicator of phototreatment efficiency. Valuable diagnostic information on large…