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Reflectance Spectra (reflectance + spectrum)
Kinds of Reflectance Spectra Selected AbstractsPrevention of Transient Discoloration of BeefJOURNAL OF FOOD SCIENCE, Issue 3 2001G. Tewari ABSTRACT Oxygen absorbent technology in conjunction with controlled atmosphere packaging(CAP) was used to prevent transient discoloration in master-packaged beef steaks. Two types of commercial O2 scavengers were used in the study. The master packs were stored at 1± 0.5 °C. The steaks from master packs were presented in a display-case for visual evaluation. Reflectance spectra from each steak-surface were obtained to estimate metmyoglobin content. Steaks packaged without O2 scavengers showed more discoloration, and had significantly higher proportions of metmyoglobin when compared to steaks with O2 scavengers, after most storage intervals (p < 0.05). Prevention of metmyoglobin formation was influenced by the number but not the type of O2 scavenger employed (p > 0.05). Keywords: oxygen scavengers, centralized meat operations, transient discoloration [source] Use of mid-infrared spectroscopy in the diffuse-reflectance mode for the prediction of the composition of organic matter in soil and litterJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2008Bernard Ludwig Abstract Mid-infrared spectroscopy (MIRS) is assumed to be superior to near-infrared spectroscopy (NIRS) for the prediction of soil constituents, but its usefulness is still not sufficiently explored. The objective of this study was to evaluate the ability of MIRS to predict the chemical and biological properties of organic matter in soils and litter. Reflectance spectra of the mid-infrared region including part of the near-infrared region (7000,400,cm,1) 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 partial least-square method and cross-validation were used to develop equations for the different constituents over selected spectra ranges after several mathematical treatments of the spectra. Mid-infrared spectroscopy predicted well the C : N ratio: the modeling efficiency EF was 0.95, the regression coefficient (a) of a linear regression (measured against predicted values) was 1.0, and the correlation coefficient (r) was 0.98. Satisfactorily (EF , 0.70, 0.8 , a , 1.2, r , 0.80) assessed were the contents of C, N, and lignin, the production of dissolved organic carbon, and the contents of carbonyl C, aromatic C, O-alkyl C, and alkyl C. However, the N mineralization rate, the microbial biomass and the alkyl,to,aromatic C ratio were predicted less satisfactorily (EF < 0.70). Limiting the sample set to mineral soils did generally not result in improved predictions. The good and satisfactory predictions reported above indicate a marked usefulness of MIRS in the assessment of chemical characteristics of soils and litter, but the accuracies of the MIRS predictions in the diffuse-reflectance mode were generally not superior to those of NIRS. [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] Reflectance spectra of iron meteorites: Implications for spectral identification of their parent bodiesMETEORITICS & PLANETARY SCIENCE, Issue 2 2010Edward A. CLOUTIS Powder spectra are invariably red-sloped over this wavelength interval and have a narrow range of visible albedos (approximately 10,15% at 0.56 ,m). Metal (Fe:Ni) compositional variations have no systematic effect on the powder spectra, increasing grain size results in more red-sloped spectra, and changes in viewing geometry have variable effects on overall reflectance and spectral slope. Roughened metal slab spectra have a wider, and higher, range of visible albedos than powders (22,74% at 0.56 ,m), and are also red-sloped. Smoother slabs exhibit greater differences from iron meteorite powder spectra, exhibiting wider variations in overall reflectance, spectral slopes, and spectral shapes. No unique spectral parameters exist that allow for powder and slab spectra to be fully separated in all cases. Spectral differences between slabs and powders can be used to constrain possible surface properties, and causes of rotational spectral variations, of M-asteroids. The magnitude of spectral variations between M-asteroids and rotational and spectral variability does not necessarily imply a dramatic change in surface properties, as the differences in albedo and/or spectral slope can be accommodated by modest changes in grain size (for powders), small changes in surface roughness (for slabs), or variations in viewing geometry. Since metal powders exhibit much less spectral variability than slabs, M-asteroid spectral variability requires larger changes in either powder properties or viewing geometry than for slabs for a given degree of spectral variation. [source] Total reflectance and Raman studies in AlyInxGa1-x-yN epitaxial layersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2010A. Margarida Bola Abstract This study comprises a set of AlyInxGa1-x-yN thin films grown on GaN/sapphire substrate by MOVPE, with In content between 2 and 8% and Al between 21 and 38%. The thin films were optically characterized by means of UV-Visible total reflectance and ,-UV-Raman scattering, performed at room temperature. It is shown that the [Al]/[In] ration influences strongly the Reflectance spectra and a good correlation has been found between the reflectance maximum located at higher energy and the band gap predicted by Vegard's law for quaternary alloys. The Raman results indicate that the LO-AlGaN-like vibration mode is the dominated vibration in good agreement with the oscillator strength values obtained theoretically [12] for this alloys. It is shown how the influence of competing effects, such as composition and strain influences the frequency observed for the LO-AlGaN-like mode (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Reflectance spectra of Munsell standard chips and their appearanceCOLOR RESEARCH & APPLICATION, Issue 3 2008Tarow Indow Abstract In this article, we present the results of analysis by two different methods for representing information in reflectance spectra of Munsell standard chips that relates to their appearance. The spectrum of a chip j is denoted as rj, where , represents wavelength , from 430 to 660 nm with 1 nm intervals. The spectrum of light reflected from a chip j under D65 is rj, × e, where e, represents the spectral power distribution of D65 illumination. In one method, singular value decomposition is applied to a matrix of (rj, × e,). Combining results of this analysis with results of human assessment experiments, we obtain four curves ,0,(H) that represent principal hue components , in Munsell Hue, , = redness, yellowness, greenness, and blueness (Fig. 6). The other method is multiple regression of each (rj, × e,) to activities of three kinds of cones in the retina. From this analysis, we obtain three curves Bq(H) that represent relative involvements of q = L, M, S cone activities in determining the appearance of Munsell Hue (Fig. 10). Two sets of curves, ,0,(H), and Bq(H), are compared with predictions from a model of higher order color mechanism (Fig. 12) that has been proposed on the basis of experiments with light stimuli of wavelength ,. It is found that ,0,(H), and Bq(H) constructed from broadband spectra of Munsell chips are interpretable in terms of this model. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 229,237, 2008 [source] Controllable Synthesis of Cu2O Microcrystals via a Complexant-Assisted Synthetic RouteEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2010Wanqun Zhang Abstract A novel method using Cu(AC)2·H2O and dimethylglyoxime as reagents has been successfully developed for the controllable synthesis of Cu2O microcrystals with distinctive morphologies, including porous hollow microspheres, octahedral microcages, and microcrystals with truncated corners and edges and octahedral microcrystals. These structures can be fine-tuned by varying reaction temperature, reaction time, and concentration. The products were characterized by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectra, and UV/Vis diffuse reflectance spectra. This is the first report of the preparation of the novel microcage structure of Cu2O through a simple solution-based route. By investigating the intermediate products which resemble the final crystal structures, a possible growth mechanism is proposed. Moreover, the investigations showed that the various 3D architectures of the as-made products exhibit different abilities to catalytically degrade rhodamine-B. Our work shows that octahedral Cu2O crystals with entirely {111} faces are photocatalytically more active than octahedral microcrystals with truncated corners and edges, suggesting the {111} faces of Cu2O nanostructures are catalytically more active than the {100} and {110} faces. Due to dual effect of the cavity structure and the {111} surfaces, the octahedral microcages with truncated corners and edges exhibit a higher extent of the photodecomposition reaction. As a result of very slow photocorrosion rate of the Cu2O microcrystal, it is expected that these microcrystals with different surfaces may find more applications in photocatalysis. [source] Predicting pasture root density from soil spectral reflectance: field measurementEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2010B. H. KUSUMO This paper reports the development and evaluation of a field technique for in situ measurement of root density using a portable spectroradiometer. The technique was evaluated at two sites in permanent pasture on contrasting soils (an Allophanic and a Fluvial Recent soil) in the Manawatu region, New Zealand. Using a modified soil probe, reflectance spectra (350,2500 nm) were acquired from horizontal surfaces at three depths (15, 30 and 60 mm) of an 80-mm diameter soil core, totalling 108 samples for both soils. After scanning, 3-mm soil slices were taken at each depth for root density measurement and soil carbon (C) and nitrogen (N) analysis. The two soils exhibited a wide range of root densities from 1.53 to 37.03 mg dry root g,1 soil. The average root density in the Fluvial soil (13.21 mg g,1) was twice that in the Allophanic soil (6.88 mg g,1). Calibration models, developed using partial least squares regression (PLSR) of the first derivative spectra and reference data, were able to predict root density on unknown samples using a leave-one-out cross-validation procedure. The root density predictions were more accurate when the samples from the two soil types were separated (rather than grouped) to give sub-populations (n = 54) of spectral data with more similar attributes. A better prediction of root density was achieved in the Allophanic soil (r2 = 0.83, ratio prediction to deviation (RPD ) = 2.44, root mean square error of cross-validation (RMSECV ) = 1.96 mg g ,1) than in the Fluvial soil (r2 = 0.75, RPD = 1.98, RMSECV = 5.11 mg g ,1). It is concluded that pasture root density can be predicted from soil reflectance spectra acquired from field soil cores. Improved PLSR models for predicting field root density can be produced by selecting calibration data from field data sources with similar spectral attributes to the validation set. Root density and soil C content can be predicted independently, which could be particularly useful in studies examining potential rates of soil organic matter change. [source] Iridescent hindwing patches in the Pipevine Swallowtail: differences in dorsal and ventral surfaces relate to signal function and contextFUNCTIONAL ECOLOGY, Issue 4 2010Ronald L. Rutowski Summary 1.,Iridescent colour signals are directional but, like diffusely reflected colours, vary within and among species in ways that may be adaptations to specific types of receivers in specific light environments. 2.,The hindwings of pipevine swallowtail butterflies exhibit brilliant blue and iridescent colour patches on the ventral surface in both sexes and on the dorsal wing surface in males. Evidence suggests that the ventral iridescent blue is a component of the warning coloration of this distasteful species, while the dorsal blue iridescent wing area is a sexual signal. Given differences in the function and ecological context of signal production, we analysed reflectance spectra from the iridescent blue areas of both field-caught and laboratory-reared animals to test several predictions about the iridescent colour patches on these wing surfaces. 3.,The ventral blue patches in the warning coloration of males and females should be most visible early and late in the day, due to wing orientation relative to sun angle. We therefore predicted that these iridescent colour patches would be brighter and of longer wavelengths than the male dorsal blue patch displayed during midday courtships. The prediction about reflectance intensity was supported but the prediction about hue was not. 4.,We predicted that the sexually selected dorsal hindwing iridescence of males would be more variable among individuals and condition dependent than the naturally selected ventral iridescent colour patches. To assess variation and condition dependence, laboratory-reared and field-captured individuals were compared. The prediction about variation was not supported, but only the dorsal wing surfaces showed evidence of being condition dependent. 5.,We investigated whether development of dorsal and ventral blue iridescence was coupled by determining correlations in colour properties between the wing surfaces. Our finding of positive correlations indicated a potential developmental constraint in the evolution of colour differences between the two wing surfaces. 6.,Results of this study suggest that some properties of iridescent coloration on the hindwing of the pipevine swallowtail (especially intensity) may have been fine-tuned by evolution in response to prevailing ambient light conditions and viewing perspectives that differ among types of signal receivers. [source] Clinical grading of oral mucosa by curve-fitting of corrected autofluorescence using diffuse reflectance spectraHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 6 2010Rupananda Jayachandra Mallia PhD Abstract Background Laser-induced autofluorescence (LIAF) and diffuse reflectance (DR) were collectively used in this clinical study to improve early oral cancer diagnosis and tissue grading. Methods LIAF and DR emission from oral mucosa were recorded on a fiber-optic spectrometer by illumination with a 404-nm diode laser and tungsten halogen lamp in 36 healthy volunteers and 40 lesions of 20 patients. Results Absorption dips in LIAF spectra at 545 and 575 nm resulting from changes in oxygenated hemoglobin were corrected using DR spectra of the same site. These corrected spectra were curve-fitted using Gaussian spectral functions to determine constituent emission peaks and their relative contribution. The Gaussian peak intensity and area ratios F500/F635 and F500/F685 were found to be useful indicators of tissue transformation. The diagnostic capability of various ratios in differentiating healthy, hyperplastic, dysplastic, and squamous cell carcinomas (SCCs) were examined using discrimination scatterplots. Conclusions The LIAF/DR technique, in conjunction with curve-fitting, differentiates different grades of dysplasia and SCC in this clinical trial and proves its potential for early detection of oral cavity cancer and tissue grading. © 2009 Wiley Periodicals, Inc. Head Neck, 2010 [source] Formation of Oxynitride as the Photocatalytic Enhancing Site in Nitrogen-Doped Titania Nanocatalysts: Comparison to a Commercial Nanopowder,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2005X. Chen Abstract A nitrogen-doped TiO2 nanocolloid has been successfully prepared and its properties compared with the commercially available TiO2 nanomaterial, Degussa P25. Several characterization techniques, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Raman scattering, and UV-visible reflectance spectra, are combined in order to determine the crystal phase and grain size, shape, degree of nitrogen incorporation, and nature of the resultant oxynitride chemical bonding on the surface and in the bulk. The high relative photocatalytic activity of the nitrogen doped-TiO2 nanocolloid is evaluated through a study of the decomposition of methylene blue under visible light excitation. The ease and degree of substitutional-insertional nitrogen doping is held accountable for the significant increase in photocatalytic activity in the porous nanocolloid versus the nitrided commercial nanopowder. It is suggested that the nitrogen incorporation produces an NO bonding region as evidenced by the resulting XPS spectrum. [source] Application of extended inverse scatter correction to mid-infrared reflectance spectra of soilJOURNAL OF CHEMOMETRICS, Issue 5-7 2005Neal B. Gallagher Abstract Scattering artifacts adversely affect infrared reflectance measurements of powders and soils, and extended inverse scatter correction (EISC) is a flexible method useful for correcting these artifacts. EISC was used to correct mid-infrared reflectance spectra of two different soils coated with dibutyl phosphate and the results were examined using regression analysis. To obtain the correction, EISC fits a measured spectrum to a reference spectrum. However, if measured spectra contain features not included in the reference spectrum the fit can be biased resulting in poor correction. Weighted and robust least squares were used to account for these potential biases. Additionally, the present work demonstrates how analyte-free samples can be used to determine basis functions for an extended mixture model used in the correction. Corrected spectra resulted in partial least squares models that performed at least as well as 2nd derivative spectra and were more interpretable. Copyright © 2006 John Wiley & Sons, Ltd. [source] Some theoretical properties of the O-PLS methodJOURNAL OF CHEMOMETRICS, Issue 2 2004Thomas Verron Abstract The objective of this paper is to present new properties of the orthogonal projections to latent structures (O-PLS) method developed by Trygg and Wold (J. Chemometrics 2002; 16: 119,128). The original orthogonal signal correction (OSC) filter of Wold et al. (Chemometrics Intell. Lab. Syst. 1998; 44: 175,185) removes systematic variation from X that is unrelated to Y. O-PLS is a more restrictive OSC filter. O-PLS removes only systematic variation in X explained in each PLS component that is not correlated with Y. O-PLS is a slight modification of the NIPALS PLS algorithm, which should make O-PLS a generally applicable preprocessing and filtering method. The computation of the O-PLS components under the constraint of being correlated with one PLS component imposes particular properties on the space spanned by the O-PLS components. This paper is divided into two main sections. First we give an application of O-PLS on near-infrared reflectance spectra of soil samples, showing some graphical properties. Then we give the mathematical justifications of these properties. Copyright © 2004 John Wiley & Sons, Ltd. [source] Interspecific variation in plumage colour among birds: species recognition or light environment?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2002Melinda K. McNaught Abstract The traditional explanation for interspecific plumage colour variation in birds is that colour differences between species are adaptations to minimize the risk of hybridization. Under this explanation, colour differences between closely related species of birds represent reproductive character displacement. An alternative explanation is that interspecific variation in plumage colour is an adaptive response to variation in light environments across habitats. Under this explanation, differences in colour between closely related species are a product of selection on signal efficiency. We use a comparative approach to examine these two hypotheses, testing the effects of sympatry and habitat use, respectively, on divergence in male plumage colour. Contrary to the prediction of the Species Isolation Hypothesis, we find no evidence that sympatric pairs of species are consistently more divergent in coloration than are allopatric pairs of species. However, in agreement with the Light Environment Hypothesis, we find significant associations between plumage coloration and habitat use. All of these results remain qualitatively unchanged irrespective of the statistical methodology used to compare reflectance spectra, the body regions used in the analyses, or the exclusion of areas of plumage not used in sexual displays. Our results suggest that, in general, interspecific variation in plumage colour among birds is more strongly influenced by the signalling environment than by the risk of hybridization. [source] Passport Examination by Polarized Infrared SpectraJOURNAL OF FORENSIC SCIENCES, Issue 4 2007Shigeru Sugawara M.S. Abstract:, In this study, a new nondestructive technique for passport examination is proposed. In this technique, linearly polarized light is used to measure Fourier transform infrared (FT-IR) reflectance spectra of films on the biographical data page. Thirty genuine and thirty-five counterfeit Japanese passports and five marketed films pasted on name cards were examined. The measured spectra were analyzed as follows. The absorption spectra were obtained by the Kramers,Kronig transformations of reflectance spectra. The peak ratios were then calculated from the absorption spectra by adding the peak areas at 1126 and 1263 cm,1 and dividing the result by the peak area at 1727 cm,1. When nonpolarized light was used, the samples could not be distinguished by comparing the peak ratios. However, when polarized light was used, they were successfully distinguished by the comparison. Therefore, polarized light is useful for the forensic discrimination of passport films by the measurement of FT-IR spectra. [source] Low-Temperature Growth of Rutile Nanorod Thin Films and their Photon-Induced PropertyJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008Jin-Ming Wu Thin films of well-crystallized pure rutile nanorods were deposited on Ti substrates through a simple solution approach at a low temperature of 353 K. Field emission scanning electron microscopic and atomic force microscopic investigations revealed topographies of both quasi-aligned and less-aligned nanorod arrays, depending on Ti grain facets. X-ray diffraction and Raman spectra analysis verified that the deposited nanorod thin film was phase-pure rutile. This rutile nanorod was identified to be single crystalline growing along the [001] direction by high-resolution transmission electron microscopy. UV-Vis diffuse reflectance spectra estimated a remarkable red shift in responsive light for the nanorods when compared with that of bulk rutile. Under illumination of artificial solar light, the ability of the rutile nanorod film to aid photodegradation of rhodamine B in water was argued to be superior to the rutile nanoparticles isolated from commercial Degussa P25, which was attributed to the unique rod-like nanostructure. [source] Comparative effect of red yeast rice (Monascus purpureus), red beet root (Beta vulgaris) and betanin (E-162) on colour and consumer acceptability of fresh pork sausages packaged in a modified atmosphereJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2006Luis Martínez Abstract Fresh pork sausages containing natural colorants, red yeast rice powder (Monascus purpureus; Frame®) or a crude red beet root (Beta vulgaris) juice or commercial betanin (E-162), at different concentrations, were packaged in an atmosphere containing 80% O2 and 20% CO2 and stored in the dark for 20 days. The following parameters were measured at 4 day intervals: instrumental colour (CIE L*, a*, b*, a*/b*, C* and h*), reflectance spectra, sensory discoloration (trained panel) and acceptability and willingness to purchase (habitual and non-habitual consumer panels) under two different lighting displays (standard fluorescent and Promolux® lamp). The use of colorants improved the colour properties of fresh pork sausages. Sausages with red yeast rice, red beet root juice and betanin had lower L* and h* and higher a* and a*/b* values than control samples. The colour properties of sausages with red beet root were the closest to control sausages, while sausages with red yeast rice had significantly lower b* values. Both natural colorants and betanin protected sausages from discoloration and extended acceptability and willingness to purchase by about 4 days, according to evaluation by habitual consumers under two different types of lighting display. Therefore, red beet root juice may be envisaged as the most suitable natural colorant for use in fresh pork sausages. Copyright © 2005 Society of Chemical Industry [source] Prediction of fat in intact cereal food products using near-infrared reflectance spectroscopy,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2005Sandra E Kays Abstract To evaluate the feasibility of an intact product approach to the near-infrared (NIR) determination of fat content, a rapid acquisition spectrometer, with an InGaAs diode-array detector and custom built sampling device, was used to obtain reflectance spectra (1100,1700 nm) of diverse cereal food products. Fat content reference data were obtained gravimetrically by extraction with petroleum ether (AOAC Method 945.16). Using spectral and reference data, partial least-squares regression analysis was applied to calculate a NIR model (n = 89) to predict fat in intact cereal products; the model was adequate for rapid screening of samples, predicting the test samples (n = 44) with root mean square error of prediction (RMSEP) of 11.8 (range 1.4,204.8) g kg,1 and multiple coefficient of determination of 0.98. Repeated repacking and rescanning of the samples did not appreciably improve model performance. The model was expanded to include samples with a broad range of particle sizes and moisture contents without reduction in prediction accuracy for the untreated samples. The regression coefficients for the models calculated indicated that spectral features at 1165, 1215 and 1395 nm, associated with CH stretching in fats, were the most critical for model development. Published in 2005 for SCI by John Wiley & Sons, Ltd. [source] Does Pond Water Reflectance Influence Double-crested Cormorant Selection of Aquaculture Ponds?JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2010Andrew A. Radomski Double-crested cormorants, Phalacrocorax auritus, are a frequent and major avian predator on channel catfish, Ictalurus punctatus, and other aquaculture species throughout the southeastern USA. Although cormorant movements and occurrence within the aquaculture production region are understood, no studies have focused on the mechanisms utilized by these avian predators to select foraging sites within these high-density aquaculture systems. The objective of this study was to determine if cormorant abundance is associated with specific (ultraviolet to visible) light reflectance spectra within commercial catfish ponds. Three commercial farms were used in this study; each farm had four ponds classified as "preferred" and another four ponds classified as "avoided" based on observing cormorant numbers for 3 mo prior to reflectance measures (>100 h observation for each pond). Reflectance and pond turbidity were measured weekly for 7 wk during the period of maximal over-wintering cormorant numbers. Water samples were collected at the surface (1 cm depth) and secchi depth (10,41 cm) at two locations (upwind and downwind sides) within each pond to determine spectral reflectance and turbidity. Average pond reflectance values were not significantly different between ponds preferred and avoided by cormorants; however, upwind reflectance significantly differed from downwind reflectance between cormorant use groups. Using cross-validation discriminant analysis, the accuracy of separating upwind ponds preferred and avoided by cormorants was over 62%. Repeated measures ANOVA identified the reflectance at 370, 380, 460, 500, 510, and 620 nm as significantly different between ponds preferred and avoided by cormorants. The lower wavelengths (380,410 nm) correspond to known UV-A sensing compounds in cormorants and the other wavelengths share characteristics associated with algal biomass. Cormorants utilize ponds that have lower algal biomass when compared with avoided ponds. [source] Diagnosis of breast cancer using diffuse reflectance spectroscopy: Comparison of a Monte Carlo versus partial least squares analysis based feature extraction techniqueLASERS IN SURGERY AND MEDICINE, Issue 7 2006Changfang Zhu MS Abstract Background and Objective We explored the use of diffuse reflectance spectroscopy in the ultraviolet-visible (UV-VIS) spectrum for the diagnosis of breast cancer. A physical model (Monte Carlo inverse model) and an empirical model (partial least squares analysis) based approach, were compared for extracting diagnostic features from the diffuse reflectance spectra. Study Design/Methods The physical model and the empirical model were employed to extract features from diffuse reflectance spectra measured from freshly excised breast tissues. A subset of extracted features obtained using each method showed statistically significant differences between malignant and non-malignant breast tissues. These features were separately input to a support vector machine (SVM) algorithm to classify each tissue sample as malignant or non-malignant. Results and Conclusions The features extracted from the Monte Carlo based analysis were hemoglobin saturation, total hemoglobin concentration, beta-carotene concentration and the mean (wavelength averaged) reduced scattering coefficient. Beta-carotene concentration was positively correlated and the mean reduced scattering coefficient was negatively correlated with percent adipose tissue content in normal breast tissues. In addition, there was a statistically significant decrease in the beta-carotene concentration and hemoglobin saturation, and a statistically significant increase in the mean reduced scattering coefficient in malignant tissues compared to non-malignant tissues. The features extracted from the partial least squares analysis were a set of principal components. A subset of principal components showed that the diffuse reflectance spectra of malignant breast tissues displayed an increased intensity over wavelength range of 440,510 nm and a decreased intensity over wavelength range of 510,600 nm, relative to that of non-malignant breast tissues. The diagnostic performance of the classification algorithms based on both feature extraction techniques yielded similar sensitivities and specificities of approximately 80% for discriminating between malignant and non-malignant breast tissues. While both methods yielded similar classification accuracies, the model based approach provided insight into the physiological and structural features that discriminate between malignant and non-malignant breast tissues. Lasers Surg. Med. © 2006 Wiley-Liss, Inc. [source] Spectral reflectance-compositional properties of spinels and chromites: Implications for planetary remote sensing and geothermometryMETEORITICS & PLANETARY SCIENCE, Issue 4 2004Edward A. Cloutis These two groups of minerals are spectrally distinct, which relates largely to differences in the types of major cations present. Both exhibit a number of absorption features in the 0.3,26 ,m region that show systematic variations with composition and can be used to quantify or constrain certain compositional parameters, such as cation abundances, and site occupancies. For spinels, the best correlations exist between Fe2+ content and wavelength positions of the 0.46, 0.93, 2.8, Restrahelen, 12.3, 16.2, and 17.5 ,m absorption features, Al and Fe3+ content with the wavelength position of the 0.93 ,m absorption feature, and Cr content from the depth of the absorption band near 0.55 ,m. For chromites, the best correlations exist between Cr content and wavelength positions of the 0.49, 0.59, 2, 17.5, and 23 ,m absorption features, Fe2+ and Mg contents with the wavelength position of the 1.3 ,m absorption feature, and Al content with the wavelength position of the 2 ,m absorption feature. At shorter wavelengths, spinels and chromites are most readily distinguished by the wavelength position of the absorption band in the 2 ,m region (<2.1 ,m for spinels, >2.1 ,m for chromite), while at longer wavelengths, spectral differences are more pronounced. The importance of being able to derive compositional information for spinels and chromites from spectral analysis stems from the relationship between composition and petrogenetic conditions (pressure, temperature, oxygen fugacity) and the widespread presence of spinels and chromites in the inner solar system. When coupled with the ability to derive compositional information for mafic silicates from spectral analysis, this opens up the possibility of deriving petrogenetic information for remote spinel- and chromite-bearing targets from analysis of their reflectance spectra. [source] Porphyrin Bleaching and PDT-induced Spectral Changes are Irradiance Dependent in ALA-sensitized Normal Rat Skin In Vivo,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2001Jarod C. Finlay ABSTRACT Photobleaching kinetics of aminolevulinic acid,induced protoporphyrin IX (PpIX) were measured in the normal skin of rats in vivo using a technique in which fluorescence spectra were corrected for the effects of tissue optical properties in the emission spectral window through division by reflectance spectra acquired in the same geometry and wavelength interval and for changes in excitation wavelength optical properties using diffuse reflectance measured at the excitation wavelength. Loss of PpIX fluorescence was monitored during photodynamic therapy (PDT) performed using 514 nm irradiation. Bleaching in response to irradiances of 1, 5 and 100 mW cm,2 was evaluated. The results demonstrate an irradiance dependence to the rate of photobleaching vs irradiation fluence, with the lowest irradiance leading to the most efficient loss of fluorescence. The kinetics for the accumulation of the primary fluorescent photoproduct of PpIX also exhibit an irradiance dependence, with greater peak accumulation at higher irradiance. These findings are consistent with a predominantly oxygen-dependent photobleaching reaction mechanism in vivo, and they provide spectroscopic evidence that PDT delivered at low irradiance deposits greater photodynamic dose for a given irradiation fluence. We also observed an irradiance dependence to the appearance of a fluorescence emission peak near 620 nm, consistent with accumulation of uroporphyrin/coproporphyrin in response to mitochondrial damage. [source] AFM and SNOM characterization of ordinary chondrites: A contribution to solving the problem of asteroid reddeningPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2010Giuliano Pompeo Abstract Space weathering (SW) is an ensemble of processes that act on a body exposed to the space environment. Typically, the exposure to SW results in the accumulation, at the surface, of nanoparticles, that are thought to be produced through a vaporization and subsequent cooling of the metallo-silicaceous components exposed to the space environment. The presence of such nanoparticles is responsible for the so-called reddening of the asteroids' reflectance spectra (i.e., the increase in Vis,NIR reflectance with increase in wavelength) observed by remote-sensing measurements. To investigate the mechanism of formation of these nanoparticles, we have employed atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) to morphologically and optically characterize ordinary chondrites (OC), the most abundant class of meteorites collected on Earth and whose parent bodies are the S-type asteroids. The AFM study reveals the occurrence of a diffuse nanophase (martensite) in the meteorite's metal inclusions. Since the same areas show a reddening of the reflectivity spectra, this suggests that such spectral modification is based on a shock-induced phase transformation of the metal components of the extraterrestrial body. To gain more insight into this nanophase and on its role in the SW of the asteroids, an optical characterization by SNOM has been performed on OCs. In this work we exploited the peculiarity of this technique to search for a correlation between the topography on the nanoscale and the spectral characteristics, at different wavelengths in the red-NIR range, of the observed nanophase. Indeed, a high-resolution mapping of the optical properties of the meteorite provides an interesting method to discriminate between martensite-based and Fe-silicaceous nanoparticles. [source] MBE growth and magneto-optical properties of ZnCdSe-ZnMnSe wire systemsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2009Takashi Matsumoto Abstract Zn0.91Cd0.09Se/Zn0.88Mn0.12Se wire array embedded in a ZnSe barrier layer has been grown on GaAs vicinal substrate by MBE under step-flow growth condition, and polarized photoluminescence (PL) and reflectance spectra have been measured in external magnetic field in the Voigt geometry with magnetic field parallel and perpendicular to the wire. The sample shows strong luminescence due to exciton recombination in the Zn0.91Cd0.09Se QWRs. Zeeman shift of the luminescence is anisotropic, that is, the energy shift depends on the direction of the magnetic field and the direction of electric field of emitted light. In reflectance spectra two dips are observed. One is active to the light polarized perpendicular to the magnetic field and the other is active to the light parallel to the magnetic field. The effect of energy separation between the two dips on the PL polarization is studied, and relative contribution of the heavy- and light-hole component to the hole states responsible for the two transitions is discussed. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photoluminescence of cubic InN films on MgO (001) substratesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008T. Inoue Abstract We have studied photoluminescence from cubic InN films grown on MgO substrates with a cubic GaN underlayer by RF N2 plasma molecular beam epitaxy. A single PL peak was observed at 0.47 eV. By analyzing the reflectance spectra of cubic InN films, we could derive the refractive index and extinction coefficient, and found the band gap energy of cubic InN is 0.48 eV, indicating that the PL peak observed at 0.47 eV is due to the interband transition of cubic InN. The difference in the PL peak energy between hexagonal and cubic InN is in good agreement with that predicted by ab-initio calculations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Molecular adsorbate induced restructuring of a stepped Cu(110) surfacePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2005N. P. Blanchard Abstract We correlate linear optical reflectance spectra with scanning tunnelling microscopy data to observe the restructuring of a stepped Cu(110) surface by exposure to molecular oxygen. Restructuring is found on the atomic and nanometer length scales. The (2 × 1)-O added row structure is formed on the stepped Cu(110) surface, independent of the occupancy of the lower lying surface state at . We find that heating the (2 × 1)-O surface results in further and considerable restructuring of the surface. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Bitumen content estimation of Athabasca oil sand from broad band infrared reflectance spectraTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2010B. Rivard Abstract Oil sand is a mixture of quartz grains, clay minerals, bitumen, water, and minor accessory minerals. There is a need in oil sands mining operations for a robust method to estimate total bitumen content in real time; and so modelling of the total bitumen content (TBC) in Athabasca oil sands of Western Canada was undertaken on the basis of hyperspectral reflectance spectra. A selection of different bitumen, water, and clay mineral spectral features (3.0,30.0,µm) was used to develop broad-band TBC predictive models that have good accuracy, with less than 1.5% error with respect to laboratory methods of bitumen assay. These models are also robust, in that they are independent of mine location. Simple broad band models, based upon previously identified Gaussian features or wavelet features, provide an incremental improvement over the currently deployed industry two-band ratio model. An improved two-band model was also developed, which makes use of a combination of the same two bands but normalised to their mean. A wavelet-based, broad-band model comprised of indices and five bands, where the bands are normalised to the mean of the bands, adequately addresses the influence of water, clay, and textural variation on selected bitumen features. This five-band model appears to produce the most robust estimator of TBC, with a dispersion of ,1.1,1.5%, which can be applied to different sites within a mine and to different mines without additional tuning or calibration, as evidenced by regression slopes of 0.99,1.0 for modelling, validation, and blind data sets. [source] Photocatalytic Activity and Electronic Structure Analysis of N-doped Anatase TiO2: A Combined Experimental and Theoretical StudyCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2009H. Gao Abstract N-Doped TiO2 photocatalysts were prepared by a hydrothermal method with tetra- n -butyl titanate (TTNB) and triethanolamine as precursors. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra (DRS), respectively. Photocatalytic activities of the anatase products were investigated on the degradation of methyl orange (MO). The incorporation of nitrogen impurity in anatase TiO2 was studied by the first-principles calculations based on the density functional theory (DFT). The calculated electronic band structures for substitutional and interstitial N-doped TiO2 indicated the formation of localized states in the band gap, which lied above the valence band. Excitation from the impurity states of N 2p to the conduction band could account for the optical absorption edge shift toward the lower energies. It was consistent with the experimentally observed absorption of N-doped samples in the visible region. [source] Preparation and Characterization of Bi3+ -TiO2 and its Photocatalytic ActivityCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2007H. Zuo Abstract Bi3+ -TiO2 photocatalysts were prepared by doping bismuth ion into the TiO2 structure in a sol-gel process. The catalyst samples were then characterized by UV-vis diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Rodamine-B (RhB) was used in this study as a model chemical with the aim of organic pollutants control. The photocatalytic degradation of RhB demonstrated that an optimal loading of bismuth 0.7,at.,% achieved the highest photodegradation rate, with the rate constant increasing by a factor of 3.89 over neat TiO2 (P25) under UV illumination (, , 320,nm). The degradation of p -nitrobenzonic acid (pNBA) was also examined to prevent/preclude/exclude/ the photosensitization pathway. GC-MS results show that pNBA can be effectively degraded and minerized to small molecules, such as quinone, acetic acid and formic acid. [source] A Novel Inorganic-Organic Composite Constructed from Cobalt(II)-Monosubstituted Polyoxometalates and Poly(amidoamine)-NH2 DendrimersCHINESE JOURNAL OF CHEMISTRY, Issue 3 2007Xiao-Feng Zhang Abstract An inorganic-organic composite was prepared by poly(amidoamine) (PAMAM) dendrimer reacting with cobalt(II)-monosubstituted polyoxometalates Na5CoII(H2O)PW11O39 (PW11Co) in an aqueous solution. The hybrid composite PW11Co/PAMAM was characterized by FT-IR, UV-Vis diffuse reflectance spectra (DR-UV-Vis), XPS, XRD and TG/DTA, indicating that the PW11Co was chemically anchored to PAMAM. The morphologies of the title composite were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic activity was evaluated by oxidation of isobutyraldehyde (IBA) to isobutyric acid (IBAc) in MeCN under mild conditions (20 °C, ambient pressure), showing that the title compound is a more effective and recoverable catalyst than corresponding PW11Co. [source] | |||||||||||||||||||||||||||||||||||||