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Near-infrared Reflectance Spectroscopy (near-infrared + reflectance_spectroscopy)
Selected AbstractsPeau sèche-rêche et "Hydratation".INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004Concept de la capture de l'eau organisée comme de la glace Synopsis About sixty years ago Frank and Evans showed, by entropy measurements, that when a "non-polar molecule dissolves in water it modifies the water structure in the direction of greater ,cristallinity', the water builds a microscopic iceberg around it" Now, we propose the "concept of ice-like-water capture": a lowering of organized ice-like water promotes aggregation (loss of solubility) of the filaggrin/keratin1/keratin10 associations through their hydrophobic patches. The capture of ice-like water may be performed by the glucoceramides-rich bilayers in stratum granulosum. Probably, the same process aggregates the proteins of corneocytes envelope as well as corneodesmosomes proteins. According to the "concept of ice-like-water capture", to regulate the keratinization, it is not total water that must be added to the stratum corneum, but ice-like water that must be removed from stratum granulosum. Both petrolatum (lipophilic ingredient) and glycerol (hydrophilic ingredient) would capture the ice-like water, most probably after combination with the lipid bilayers of stratum corneum. Moisturizing cream, when organized in secondary droplets is likely to perform the same action. Measurements by near-infrared reflectance spectroscopy of the skin show that petrolatum; glycerol and/or moisturizing cream enhance the quantity of bulk water (1890,1897 nm band). As the ice-like water is the complement of bulk water, the enhanced bulk water let presume an ice-like water lessening. Some desynchronization (late or forward) of the keratinization/differentiation which confer the somatosensory problems associated with "dry and flaky skin" may be linked to an excess or lack of ice-like. For instance, the winter xerosis, very common by chilling weather, could be explained by an increase of ice-like water driven by the fall of the temperature. Résumé En s'appuyant: 1°-sur d'anciens travaux de thermodynamique montrant, d'une part que les molécules d'eau autour des zones apolaires en solution dans l'eau s'organise selon une structure d'eau-comme-de-la-glace, d'autre part qu'en l'absence de cette eau-comme-de-la-glace les molécules de protéines s'agrègent par leurs zones hydrophobes; 2°-sur des travaux récents utilisant la spectroscopie de l'infrarouge proche; technique qui permet de mesurer la quantité d'eau-en-vrac, forme que prend l'eau-comme-de-la-glace après sa fusion lors de l"établissement de liaisons/interactions hydrophobes; nous proposons le "concept de la capture de l"eau-comme-de-la-glace" selon lequel : 1° la différenciation des kératinocytes, qui se traduit à la fois par l'agrégation des trios filaggrine/K1/K10 (ainsi que notamment la formation de l'enveloppe des cornéocytes et des cornéodesmosomes) est promue par une baisse de la teneur en eau organisée dans le stratum granulosum. La captation de l'eau-comme-de-la-glace pourrait être assurée in situ par la structure lipidique riche en glucocéramides dont l'apparition dans le stratum granulosum est contemporaine du début de la baisse de la teneur en eau; 2° contrairement à la "tradition", la peau sèche-rêche n'est pas améliorée par une augmentation de l'hydratation du stratum corneum mais par la capture d'eau-comme-de-la-glace dans le stratum granulosum. 3° le glycérol, la Vaseline et les crèmes "hydratantes" peuvent concourir à cette capture d'eau-comme-de-la-glace, vraisemblablement après s"être combinés aux bicouches céramidiques du stratum corneum, et ainsi agir depuis ce stratum sur le stratum granulosum. 4°-la baisse hivernale de la température provoque une baisse de la quantité d'eau organisée et confère une aggravation de la peau sèche-rêche. 5°-une désynchronisation de la synthèse ou une modification de la structure et/ou de la composition des bicouches glucocéramidiques du stratum granulosum pourraient être à l'origine de certains types de peau sèche-rêche. [source] Near-infrared spectroscopy can predict the composition of organic matter in soil and litterJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2006Thomas Terhoeven-Urselmans Abstract The usefulness and limitations of near-infrared reflectance spectroscopy (NIRS) for the assessment of several soil characteristics are still not sufficiently explored. The objective of this study was to evaluate the ability of visible and near-infrared reflectance (VIS-NIR) spectroscopy to predict the composition of organic matter in soils and litter. Reflectance spectra of the VIS-NIR region (400,2500 nm) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C-CPMAS-NMR spectroscopy. A modified partial least-square method and cross-validation were used to develop equations for the different constituents over the whole spectrum (1st to 3rd derivation). Near-infrared spectroscopy predicted well the C : N ratios, the percentages of O-alkyl C and alkyl C, the ratio of alkyl C to O-alkyl C, and the sum of phenolic oxidation products: the ratios of standard deviation of the laboratory results to standard error of cross-validation (RSC) were greater than 2, the regression coefficients (a) of a linear regression (measured against predicted values) ranged from 0.9 to 1.1, and the correlation coefficients (r) were greater than 0.9. Satisfactorily (0.8 , a , 1.2, r , 0.8, and 1.4 , RSC , 2.0) assessed were the contents of C, N, and production of DOC, the percentages of carbonyl C and aromatic C and the ratio of alkyl C to aromatic C. However, the N-mineralization rate and the microbial biomass were predicted unsatisfactorily (RSC < 1.4). The good and satisfactory predictions reported above indicate a marked usefulness of NIRS in the assessment of biological and chemical characteristics of soils and litter. [source] Preliminary study on the use of near-infrared reflectance spectroscopy to assess nitrogen content of undried wheat plantsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2007Alejandro Morón Abstract Near-infrared reflectance (NIR) spectroscopy combined with chemometrics was used to assess nitrogen (N) and dry matter content (DM) and chlorophyll in whole-wheat plant (Triticum aestivum L). Whole-wheat plant samples (n = 245) were analysed by reference method and by visible and NIR spectroscopy, in fresh (n = 182) and dry (n = 63) presentations, respectively. Calibration equations were developed using partial least squares (PLS) and validated using full cross-validation (leave-one-out method). Coefficient of determination in calibration (R2CAL) and the standard error of cross-validation (SECV) for N content in fresh sample presentation, after second derivative, were 0.89 (SECV: 0.64%), 0.86 (SECV: 0.66%) and 0.82 (SECV: 0.74%) using the visible + NIR, NIR and visible wavelength regions, respectively. Dry sample presentation gave better R2CAL and SECV for N compared with fresh presentation (R2CAL > 0.90, SECV < 0.20%) using visible + NIR. The results demonstrated that NIR is a suitable method to assess N concentration in wheat plant using fresh samples (unground and undried). Copyright © 2006 Society of Chemical Industry [source] Measurement of pesticide residues in peppers by near-infrared reflectance spectroscopyPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2010María-Teresa Sánchez Abstract BACKGROUND: Peppers are a frequent object of food safety alerts in various member states of the European Union owing to the presence in some batches of unauthorised pesticide residues. This study assessed the viability of near-infrared reflectance spectroscopy (NIRS) for the measurement of pesticide residues in peppers. Commercially available spectrophotometers using different sample-presentation methods were evaluated for this purpose: a diode-array spectrometer for intact raw peppers and two scanning monochromators fitted with different sample-presentation accessories (transport and spinning modules) for crushed peppers and for dry extract system for infrared analysis (DESIR), respectively. RESULTS: Models developed using partial least squares,discriminant analysis (PLS2-DA) correctly classified between 62 and 68% of samples by presence/absence of pesticides, depending on the instrument used. At model validation, the highest percentage of correctly classified samples,75 and 82% for pesticide-free and pesticide-containing samples respectively,were obtained for intact peppers using the diode-array spectrometer. CONCLUSION: The results obtained confirmed that NIRS technology may be used to provide swift, non-destructive preliminary screening for pesticide residues; suspect samples may then be analysed by other confirmatory analytical methods. Copyright © 2010 Society of Chemical Industry [source] | ||||||||||