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Total Reflectance (total + reflectance)
Terms modified by Total Reflectance Selected AbstractsRapid Profiling of Swiss Cheese by Attenuated Total Reflectance (ATR) Infrared Spectroscopy and Descriptive Sensory AnalysisJOURNAL OF FOOD SCIENCE, Issue 6 2009N.A. Kocaoglu-Vurma ABSTRACT:, The acceptability of cheese depends largely on the flavor formed during ripening. The flavor profiles of cheeses are complex and region- or manufacturer-specific which have made it challenging to understand the chemistry of flavor development and its correlation with sensory properties. Infrared spectroscopy is an attractive technology for the rapid, sensitive, and high-throughput analysis of foods, providing information related to its composition and conformation of food components from the spectra. Our objectives were to establish infrared spectral profiles to discriminate Swiss cheeses produced by different manufacturers in the United States and to develop predictive models for determination of sensory attributes based on infrared spectra. Fifteen samples from 3 Swiss cheese manufacturers were received and analyzed using attenuated total reflectance infrared spectroscopy (ATR-IR). The spectra were analyzed using soft independent modeling of class analogy (SIMCA) to build a classification model. The cheeses were profiled by a trained sensory panel using descriptive sensory analysis. The relationship between the descriptive sensory scores and ATR-IR spectra was assessed using partial least square regression (PLSR) analysis. SIMCA discriminated the Swiss cheeses based on manufacturer and production region. PLSR analysis generated prediction models with correlation coefficients of validation (rVal) between 0.69 and 0.96 with standard error of cross-validation (SECV) ranging from 0.04 to 0.29. Implementation of rapid infrared analysis by the Swiss cheese industry would help to streamline quality assurance. [source] Study of pseudo-multilayer structures based on starch-polycaprolactone extruded blendsPOLYMER ENGINEERING & SCIENCE, Issue 6 2009Laurent Bélard This article is focused on the analysis of the structure-process relationships of biodegradable materials. It is mainly focused on the analysis of phase separation phenomenon occurring during the extrusion of plasticized starch/polycaprolactone blends, in a slit die. Rheological characterizations are carried out, in-line in an instrumented slit die at the exit of the extruder and, out-line with different rheometers. In certain conditions, a pseudo-multilayer structure can be generated with a polyester rich skin. Then, Electron Spectroscopy for Chemical Analysis (ESCA) and Fourier Transformed Infrared Attenuated Total Reflectance (FTIR-ATR) analyses are conducted to evaluate semi-quantitatively the polyester surface enrichment. In the range of available shear rates, the phase separation is mainly driven by the molecular weight of polycaprolactone, linked to its molten state viscosity. Three zones of surface enrichment, dependent on the molecular weights, are identified. Above 60,000 g·mol,1, no surface enrichment could be detected; below 37,000 g·mol,1, the phase separation occurs with no dependence on the processing conditions; between these two limits, the phase separation depends on both, the formulation and the processing conditions. A correlation between the rheological measurements and the phase separation is given. A predictive criterion based on the viscous behavior of the blend is established. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [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] Effects of pubescence and waxes on the reflectance of leaves in the ultraviolet and photosynthetic wavebands: a comparison of a range of speciesPLANT CELL & ENVIRONMENT, Issue 1 2002M. G. Holmes Abstract Total reflectance of ultraviolet and photosynthetically effective wavelengths was measured for a range of different leaf types. Two approaches were employed. Firstly, reflectance of monochromatic wavebands at 330 and 680 nm was measured for a total of 45 different species covering a wide range of genera. In the second, specific leaf types that displayed different degrees of reflectance were treated to remove hairs and waxes that contributed to their reflectance. Selected waxy and non-waxy leaves were also studied in more detail over the spectral range 270,500 nm. It was found that both pubescence (presence of hairs) and glaucousness (presence of a thick epicuticular wax layer) had marked effects on total reflectance. Pubescent leaves tended to be more effective in reflecting longer wavelengths than ultraviolet radiation. The extent of this effect depended on hair type. Glaucous leaves demonstrated that surface waxes were very effective reflectors of both UV and longer wavelength radiation. [source] Dentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restorationEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2010Andy C. Ritts Ritts AC, Li H, Yu Q, Xu C, Yao X, Hong L, Wang Y. Dentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restoration. Eur J Oral Sci 2010; 118: 510,516. © 2010 Eur J Oral Sci The objective of this study was to investigate the treatment effects of non-thermal atmospheric gas plasmas on dentin surfaces used for composite restoration. Extracted unerupted human third molars were prepared by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. The dentin surfaces were treated using a non-thermal atmospheric argon plasma brush for various periods of time. The molecular changes of the dentin surfaces were analyzed using Fourier transform infrared spectrophotometry/attenuated total reflectance (FTIR/ATR), and an increase in the amount of carbonyl groups was detected on plasma-treated dentin surfaces. Adper Single Bond Plus adhesive and Filtek Z250 dental composite were applied as directed. To evaluate the dentin/composite interfacial bonding, the teeth thus prepared were sectioned into micro-bars and analyzed using tensile testing. Student,Newman,Keuls tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s of plasma treatment. However, the bonding strength to plasma-treated inner dentin did not show any improvement. It was found that plasma treatment of the peripheral dentin surface for up to 100 s resulted in an increase in the interfacial bonding strength, while prolonged plasma treatment of dentin surfaces (e.g. 5 min) resulted in a decrease in the interfacial bonding strength. [source] Tuning the Refractive Index of Polymers for Polymer Waveguides Using Nanoscaled Ceramics or Organic Dyes,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2004J. Böhm Plastic Optical Fibers (POF) show advantageous properties like high flexibility and their cost advantage in comparison to glass fibers. The refractive indices of core and cladding have to be modified in order to get total reflectance. Thus, there is a strong demand for refractive index adjustable polymers with improved transmission properties in the visible and the NIR range. Inorganic nanosized particles or organic dyes homogeniously dispersed or solved in the polymer matrix allow a tailored increase or decrease of the refractive index of various polymers. [source] Quantification of Grafting Densities Achieved via Modular "Grafting-to" Approaches onto Divinylbenzene MicrospheresADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Leena Nebhani Abstract The surface modification of divinylbenzene (DVB)-based microspheres is performed via a combination of reversible addition fragmentation chain transfer (RAFT) polymerization and rapid hetero-Diels,Alder (HDA) chemistry with the aim of quantifying the grafting densities achieved using this "grafting-to" method. Two variants of the RAFT-HDA concept are employed to achieve the functionalization of the microspheres. In the first approach, the microspheres are functionalized with a highly reactive diene, i.e., cyclopentadiene, and are subsequently reacted with polystyrene chains (number-averaged molecular weight, Mn,=,4200,g,mol,1; polydispersity index, PDI,=,1.12.) that carry a thiocarbonyl moiety functioning as a dienophile. The functionalization of the microspheres is achieved rapidly under ambient conditions, without the aid of an external catalyst. The surface grafting densities obtained are close to 1.2,×,1020 chains per gram of microspheres. In the second approach, the functionalization proceeds via the double bonds inherently available on the microspheres, which are reacted with poly(isobornyl acrylate) chains carrying a highly dienophilic thiocarbonyl functionality; two molecular weights (Mn,=,6000,g,mol,1, PDI,=,1.25; Mn,=,26,000,g,mol,1, PDI,=,1.26) are used. Due to the less reactive nature of the dienes in the second approach, functionalization is carried out at elevated temperatures (T,=,60,°C) yet in the absence of a catalyst. In this case the surface grafting density is close to 7,chains,nm,2 for Mn,=,6000,g,mol,1 and 4,chains,nm,2 for Mn,=,26,000,g,mol,1, or 2.82,×,1019 and 1.38,×,1019,chains g,1, respectively. The characterization of the microspheres at various functionalization stages is performed via elemental analysis for the quantification of the grafting densities and attenuated total reflectance (ATR) IR spectroscopy as well as confocal microscopy for the analysis of the surface chemistry. [source] Reduced barrier efficiency in axillary stratum corneumINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2002A. Watkinson Synopsis The skin of the axilla is cosmetically important with millions of consumers daily applying antiperspirant/deodorant products. Despite this, we know virtually nothing about axillary skin or how antiperspirant (AP) use impacts upon it. To characterize the axillary stratum corneum and determine whether this is a unique skin type, we have looked at stratum corneum composition and function, particularly its barrier properties, and compared it with other body sites. Transepidermal water loss (TEWL) and corneosurfametry (CSM) revealed a reduced barrier function in the axilla. HPTLC analysis of the stratum corneum lipids demonstrated statistically elevated levels of fatty acids, ceramides, and particularly cholesterol in the axilla. Both ceramide and cholesterol did not appear to change with depth, indicating that they were predominantly of stratum corneum origin. On the other hand, at least some of the fatty acid had a sebaceous origin. We hypothesized that the reduced barrier function might be owing to the changes in the crucial ceramide : cholesterol ratio. To address this, we used a combination of attenuated total reflectance,Fourier-transformed infrared spectroscopy (ATR,FTIR) with cyanoacrylate sampling. These results demonstrated more ordered lipid-lamellae phase behaviour in the axilla, suggesting that the elevated cholesterol might form crystal microdomains within the lipid lamellae, allowing an increase in water flux. Since an exaggerated application of antiperspirant had no effect upon the axilla barrier properties, it is concluded that this region of skin physiologically has a reduced barrier function. Résumé La peau des aisselles est importante du point de vue cosmétique, avec des millions de consommateurs appliquant quotidiennement des produits antitranspirants/déodorants. Malgré cela, nous ne connaissons pratiquement rien de la peau des aisselles ou de l'impact que l'utilization d'antitranspirants peut avoir sur celle-ci. Afin de caractériser la stratum corneum des aisselles et de déterminer si elle constitue un type de peau spécifique, nous avons examiné la composition et la fonction de la stratum corneum, en particulier ses propriétés de barrière, comparées à d'autres zones du corps. La perte d'eau trans -épidermique (trans -epidermal water loss TEWL) et la cornéosurfamétrie (CSM) ont révélé une fonction barrière réduite dans les aisselles. L'analyse HPTLC des lipides de la stratum corneum a démontré la présence de niveaux statistiquement plus élevés d'acides gras, de céramides et en particulier de cholestérol dans la peau axillaire. Ni les céramides ni le cholestérol n'ont semblé changer en fonction de la profondeur, indiquant qu'ils sont probablement originaires du stratum corneum. Cependant, au moins une partie des acides gras avaient une origine sébacée. Notre hypothèse est qu'une réduction de la fonction de barrière de la stratum corneum axillaire est peut-être due à des changements dans le rapport crucial céramides : cholestérol. Pour examiner cette hypothèse, nous avons utilisé la spectroscopie infrarouge par transformée de Fourier ATR[l'attenuated total reflectance Fourier-transformed infrared spectroscopy (ATR,FTIR)] combinée à l'échantillonnage au cyanoacrylate. Ces résultats ont dévoilé un comportement de phase de lamelles lipidiques plus ordonnée dans les aisselles, suggérant que le cholestérol puisse former des microdomaines cristallins à l'intérieur des lamelles lipidiques, ce qui permettrait ainsi une augmentation du flux d'eau. Puisque l'application exagérée d'anti-transpirant n'a pas eu d'effet sur les propriétés de barrière des aisselles, nous concluons que cette région de la peau a une fonction de barrière physiologique réduite. [source] Potential Modulated Attenuated Total Reflectance Spectroscopy of Prussian Blue Films on ITOISRAEL JOURNAL OF CHEMISTRY, Issue 3 2006Zeynep Ozkan Araci Potential modulated attenuated total reflectance (PM-ATR) spectroscopy has been employed to study charge transfer processes in Prussian blue (PB) films deposited on indium tin oxide (ITO) electrodes. PM-ATR is a planar waveguide-based spectroelectrochemical technique in which the optical response of an electroactive film is measured as a function of applied potential and modulation frequency. The multiple internal reflection geometry of PM-ATR provides a significant sensitivity advantage over the single external reflectance geometry that has been employed in most prior electroreflectance studies. The apparent electron transfer rate of PB on ITO obtained using PM-ATR was compared to that obtained with conventional cyclic voltammetry; the respective rates, 0.33 ± 0.15 s,1 (n = 3) and 0.71 ± 0.37 s,1 (n = 10), are in good agreement. [source] ,Green earths': vibrational and elemental characterization of glauconites, celadonites and historical pigmentsJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2008Francesca Ospitali Abstract ,Green earths' are employed since antiquity as pigments in the creation of artworks. The minerals responsible for the colour belong to four groups: (1) the clayey micas celadonite and glauconite, undoubtedly the most common; (2) smectites; (3) chlorites; (4) serpentines. Whereas there have been several studies on clayey materials, mineralogical analyses in the field of cultural heritage are mainly limited to the identification of the green earth without specific characterization of the mineralogical species. This work shows a preliminary characterization by the multi-techniques approach of some raw minerals (glauconite, celadonite and ferroceladonite). Vibrational analyses have been correlated with elemental analyses, thanks to the hyphenated instrumentation of scanning electron microscopy with EDS and Raman structural and chemical analyser (SEM-EDS-SCA) probes, which permitted collection of EDS and Raman spectra on the same microscopic area. Micro-Raman and Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopies were able to distinguish between celadonite and glauconite. The use of different lasers revealed resonance effects in the Raman spectra. In addition to pure minerals, archaeological samples and commercial green earths were also analysed, thereby enabling a more precise classification of the green pigments in heterogeneous samples such as wall paintings. Some commercially available green earths were found to contain organic dyes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Detection of inverted beet sugar adulteration of honey by FTIR spectroscopyJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001S Sivakesava Abstract A combination of Fourier transform infrared (FTIR) spectroscopy and multivariate statistics as a screening tool for the determination of beet medium invert sugar adulteration in three different varieties of honey is discussed. Honey samples with different concentrations of beet invert sugar were scanned using the attenuated total reflectance (ATR) accessory of the Bio-Rad FTS-6000 Fourier transform spectrometer. The spectral wavenumber region between 950 and 1500,cm,1 was selected for partial least squares (PLS) regression to develop calibration models for beet invert sugar determination in honey samples. Results from the PLS (first derivative) models were slightly better than those obtained with other calibration models. Predictive models were also developed to classify beet sugar invert in three different varieties of honey samples using discriminant analysis. Spectral data were compressed using the principal component method, and linear discriminant and canonical variate analyses were used to detect the level of beet invert sugar in honey samples. The best predictive model for adulterated honey samples was achieved with canonical variate analysis, which successfully classified 88,94 per cent of the validation set. The present study demonstrated that Fourier transform infrared spectroscopy could be used for rapid detection of beet invert sugar adulteration in different varieties of honey. © 2001 Society of Chemical Industry [source] Hydrophilization of polypropylene films by using migratory additivesJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2007Siqiang Zhu Linear and branched hydrophilic additives of various molecular weights (MWs) were extruded with polypropylene (PP) to make blend films. The surface-modifying additives included polyethylene glycol (PEG), hydroxyl-terminated four-arm polyethylene oxide (PEO), and a commercial hydrophilic additive, Irgasurf HL560. Films were extruded by using a twin-screw microcompounder at 200°C, and the resulting film thickness was 100 ,m. Attenuated total reflectance (ATR)-FTIR spectrometry and water contact angle measurements were performed on the film surfaces over time to investigate the additive migration behavior. Although ATR-FTIR detected concentration increases for all additives in the subsurface region, there was no significant improvement in surface hydrophilicity for the PEGs and four-arm PEOs in the same period of time as water contact angles were measured on the surfaces. Among the linear additives, low MW PEG (1 kDa) was found to migrate faster than the high MW varieties. The linear PEG and four-arm PEO with MW higher than 2 kDa did not exhibit significant migration to the surface within a month. Irgasurf was found to change the surface wettability effectively in a relatively short time. J. VINYL ADDIT. TECHNOL., 13:57,64, 2007. © 2007 Society of Plastics Engineers. [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] Effects of pubescence and waxes on the reflectance of leaves in the ultraviolet and photosynthetic wavebands: a comparison of a range of speciesPLANT CELL & ENVIRONMENT, Issue 1 2002M. G. Holmes Abstract Total reflectance of ultraviolet and photosynthetically effective wavelengths was measured for a range of different leaf types. Two approaches were employed. Firstly, reflectance of monochromatic wavebands at 330 and 680 nm was measured for a total of 45 different species covering a wide range of genera. In the second, specific leaf types that displayed different degrees of reflectance were treated to remove hairs and waxes that contributed to their reflectance. Selected waxy and non-waxy leaves were also studied in more detail over the spectral range 270,500 nm. It was found that both pubescence (presence of hairs) and glaucousness (presence of a thick epicuticular wax layer) had marked effects on total reflectance. Pubescent leaves tended to be more effective in reflecting longer wavelengths than ultraviolet radiation. The extent of this effect depended on hair type. Glaucous leaves demonstrated that surface waxes were very effective reflectors of both UV and longer wavelength radiation. [source] Analysis of human tear fluid by Fourier transform infrared spectroscopyBIOPOLYMERS, Issue 1 2005Yasushi Nagase Abstract The purpose of this research is to find some useful spectroscopic factors in human tear fluid contents to monitor diurnal changes of the physicochemical ocular conditions noninvasively. All tear fluid samples were collected with glass microcapillary tubes from both eyes of three donors and analyzed by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR,ATR). We measured the peak intensities at 2852, 1735, 1546, and 1242 cm,1, and the peak intensity ratios among those peaks in the second derivative spectra. We found significant diurnal and individual variations in those peak intensities for tear fluid obtained from right and left eyes. Among these variations, we observed significant changes in tear samples between right and left eyes. In this case the peak intensity ratio between 1242 (phosphate ester) and 2852 cm,1 (fatty acid methylene) of right eye tear fluid was increased in the afternoon (1600 to 1900 h), while that of left eye tear fluid did not change significantly. In the ratio between 1242 (phosphate ester) and 1546 cm,1 (amide II), the difference was not observed between both eyes. We conclude that the difference in diurnal variations of biochemical constituents between right and left eye tear fluids could be monitored noninvasively and nondestructively by FTIR technique and this method could be useful in the future for tear diagnoses.© 2005 Wiley Periodicals, Inc. Biopolymers 79: 18,27, 2005 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Sugar Metabolic Analysis of Suspensions of Plant Cells Using an FT-IR/ATR MethodBIOTECHNOLOGY PROGRESS, Issue 3 2001Atsushi Hashimoto A simple, rapid and accurate evaluation of the sugar uptake rate of suspended plant cells from culture media was developed with the predicted sugar contents measured by mid-infrared spectroscopy using a Fourier transform infrared (FT-IR) spectrometer equipped with an attenuated total reflectance (ATR) accessory. We performed plant cell cultivation with Nicotiana tabacum cv. Bright Yellow No.2 (TBY-2) in culture media, which had various combinations of glucose, fructose and sucrose concentrations at the initial stage, and measured simultaneously each sugar content in the medium by the FT-IR/ATR method. By applying a logistic function to the predicted sugar contents and cell density in the medium during cultivation, the specific sugar uptake rates by the suspended TBY-2 cells were easily and continuously obtained. Thus the kinetic sugar uptake phenomena by the TBY-2 cells were well confirmed overall using the developed method. Additionally it was found that the fraction of sucrose of the initial total sugar content might kinetically affect the sugar uptake process and cell growth. Also, the relationship between the nondimensional cell density and sucrose content could be classified into three groups on the basis of the initial fraction of sucrose. [source] Effects of Polymer Architecture and Composition on the Adhesion of Poly(tetrafluoroethylene)CHEMPHYSCHEM, Issue 6 2006Chen-Yuan Tu Dr. Abstract Poly(glycidyl methacrylate), PGMA, chains in linear and arborescent structures were incorporated onto surfaces of poly(tetrafluoroethylene), PTFE, films by hydrogen plasma and ozone treatment and atom transfer radical polymerization. The epoxide groups of the PGMA chains were further reacted with acetic acid (AAc), oxalic acid (XAc), allyl amine (AA), and ethylenediamine (EDN) to introduce hydroxyl and amine groups to the surfaces of the PTFE films. Surface characterizations performed by Fourier Transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the surface modification and the chemical structure. The PGMA chains in arborescent structures show a high effectiveness for the enhancement of the adhesion of PTFE films. The adhesion of PTFE films was also significantly enhanced by ring-opening reactions of the PGMA epoxide groups with acetic acid and amine compounds. A high value of 9.5 N,cm,1 in the optimum 180° peel strength test was observed with PTFE/copper assemblies. [source] | |||||||||||||||||||