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Sample records for attenuated total reflectance

  1. Fourier transform infrared - attenuated total reflection for wheat grain

    NASA Astrophysics Data System (ADS)

    Suchowilska, E.; Kandler, W.; Wiwart, M.; Krska, R.

    2012-04-01

    Mid-infrared regions of the spectrum of grain of four Triticum species were analyzed using Fourier transform infrared - attenuated total reflection. Significant variations were noted in the absorbance of all studied taxa over four wavenumber ranges. The principal component analysis supported strong discrimination of the four examined species. The percentage of variation explained by the first two principal component analyses reached 95.04%, including principal components 1-72.16% and 2-22.88%. The applied method supports quick identification of the grains of various hulled species of wheat and it is a useful tool for evaluating the seeds and food products obtained from those cereal species.

  2. Critical coupling of surface plasmons in graphene attenuated total reflection geometry

    NASA Astrophysics Data System (ADS)

    Cuevas, Mauro

    2016-12-01

    We study the optical response of an attenuated total reflection (ATR) structure in Otto configuration with graphene sheet, paying especial attention to the occurrence of total absorption. Our results show that due to excitation of surface plasmons on the graphene sheet, two different conditions of total absorption may occur. At these conditions, the energy loss of the surface plasmon by radiation is equal to its energy loss by absorption into the graphene sheet. We give necessary conditions on ATR parameters for the existence of total absorption.

  3. High-sensitivity attenuated total internal reflection continuous-wave terahertz imaging

    NASA Astrophysics Data System (ADS)

    Liu, Hongxiang; Wang, Yuye; Xu, Degang; Wu, Limin; Yan, Chao; Yan, Dexian; Tang, Longhuang; He, Yixin; Feng, Hua; Yao, Jianquan

    2017-09-01

    We demonstrate an attenuated total internal reflection imaging system. The surface information of the sample on top of a prism can be acquired by two-dimensionally scanning this prism moving in the vertical plane with horizontally incident continuous terahertz waves at a fixed height. The principles and feasibility of this method are investigated. The effective imaging area on the prism, image resolution and polarization dependence of contrast enhancement and stability improvement are analyzed. Examples including solid agar, distilled water and porcine tissue are presented, demonstrating the method’s advantages of high sensitivity and simple sample preparation. The experimental and theoretical results consistently show that p-polarization contributes to enhanced image contrast and more stable intensity of the attenuated total internal reflected signal.

  4. Detection of explosives traces on documents by attenuated total reflection method

    NASA Astrophysics Data System (ADS)

    Boreysho, A. S.; Bertseva, E. V.; Korepanov, V. S.; Morosov, A. V.; Savin, A. V.; Strakhov, S. Y.

    2007-06-01

    The technical devices of explosives trace detection are discussed in this work. The attenuated total reflection method (ATR) is considered for detection of explosives traces on different things (documents, clothes, fingers). The results of experiments with Fourier spectrometer and ATR attachment for explosive trace detection are presented. The optical scheme and design of the compact testing device are discussed. The device includes the document information scanner and at the same time - the trace detector of explosives on the document cover.

  5. Determination of styrene-butadiene rubber composition by attenuated total internal reflection infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Orlov, A. S.; Kiselev, S. A.; Kiseleva, E. A.; Budeeva, A. V.; Mashukov, V. I.

    2013-03-01

    A rapid method for determining the composition of styrene-butadiene rubber using attenuated total internal reflection infrared spectroscopy was proposed. PMR and 13C NMR spectroscopy and infrared transmission spectroscopy were used as absolute techniques for determining the compositions of calibration samples. It was shown that the method was applicable to a wide range of styrene-butadiene rubbers, did not require additional sample preparation, and was easily reproducible.

  6. Attenuated Total Reflection (ATR) Sampling in Infrared Spectroscopy of Heterogeneous Materials Requires Reproducible Pressure Control.

    PubMed

    Lu, Zhenyu; Cassidy, Brianna M; DeJong, Stephanie A; Belliveau, Raymond G; Myrick, Michael L; Morgan, Stephen L

    2017-01-01

    Attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy, in which the sample is pressed against an internal reflection element, is a popular technique for rapid IR spectral collection. However, depending on the accessory design, the pressure applied to the sample is not always well controlled. While collecting data from fabrics with heterogeneous coatings, we have observed systematic pressure-dependent changes in spectra that can be eliminated by more reproducible pressure control. We also described a pressure sensor adapted to work with an ATR tower to enable more precise control of pressure during ATR sampling.

  7. Study of electronic transitions by using attenuated total reflectance spectroscopy in the far-UV region

    NASA Astrophysics Data System (ADS)

    Morisawa, Yusuke; Tachibana, Shin; Ehara, Masahiro; Ozaki, Yukihiro

    2016-09-01

    The wavelength region shorter than 200 nm, far-ultraviolet (FUV) region, is very rich in information about the electronic states and structure of a molecule. Since the molar absorption coefficient is very high ( 105 mol-1 dm3 cm-1) in the FUV region, the electronic states and structure mainly for gas molecules has been investigated for a long time. On the other hand, as to molecules in the condensed phase transmittance spectra could not measure because of high molecular density, and reflection spectroscopy has been used to observe spectra of solid samples in the FUV region. However, for liquid samples generally either absorption spectroscopy or specular reflection spectroscopy was difficult to observe. Accordingly, FUV spectroscopy for liquid samples has been a relatively undeveloped research area. To solve the above difficulties of FUV spectroscopy we have recently developed a totally new UV spectrometer based on attenuated total reflection (ATR) that enables us to measure spectra of liquid and solid samples in the 140-280 nm region. This paper shows the studies by the attenuated total reflection far-ultraviolet (ATR-FUV) spectroscopy. These investigations elucidate the electronic structure and electronic transition in the FUV region for molecules such as n- and branched alkanes, alcohols, ketones, amides, and nylons in the liquid or solid phase. The consistent assignments were performed with a help of quantum chemical calculation.

  8. Terahertz time domain attenuated total reflection spectroscopy with an integrated prism system.

    PubMed

    Nakanishi, Atsushi; Kawada, Yoichi; Yasuda, Takashi; Akiyama, Koichiro; Takahashi, Hironori

    2012-03-01

    We demonstrated attenuated total reflection (ATR) spectroscopy with an integrated prism system that included a terahertz emitter, a terahertz receiver, and an ATR prism. The ATR prism had two internal off-axis parabolic mirrors for, respectively, collimating and focusing the terahertz waves. The Fresnel loss at each interface was reduced, and the total propagation efficiency was 3.36 times larger than when using a non-integrated prism system. The refractive index of water samples calculated from the experimental data showed good agreement with values reported in the literature.

  9. An effective medium study of surface plasmon polaritons in nanostructured gratings using attenuated total reflection

    SciTech Connect

    Tyboroski, M. H.; Anderson, N. R.; Camley, R. E.

    2014-01-07

    Recent work studied surface plasmon resonances in structured materials by the method of attenuated total reflection using a prism on top of a metallic grating. That calculation considered Transverse Magnetic polarized radiation, involved an expansion in 121 Fourier modes, and found a number of interesting features. Many of these features were attributed to localized plasmons or other factors, which arise from a discrete structure. We use a simple effective medium theory to address the same problem, and find many of the same reflection features observed in the more complex calculation, indicating that localization is not an important factor. We also evaluate the possibility of using some of the new features in the reflection spectrum for bio-sensing and find that the sensitivity of the system to small changes in relative permittivity is increased compared to some standard methods.

  10. Atomic Scale Flatness of Chemically Cleaned Silicon Surfaces Studied by Infrared Attenuated-Total-Reflection Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sawara, Kenichi; Yasaka, Tatsuhiro; Miyazaki, Seiichi; Hirose, Masataka

    1992-07-01

    Hydrogen-terminated Si(111) and Si(100) surfaces obtained by aqueous HF or pH-modified (pH{=}5.3) buffered-HF (BHF) treatments have been characterized by a Fourier transform infrared (FT-IR) attenuated-total-reflection (ATR) technique. The BHF treatment provides better surface flatness than the HF treatment. Pure water rinse is effective for improving the Si(111) surface flatness, while this is not the case for Si(100) because the pure water acts as an alkaline etchant and promotes the formation of (111) microfacets or microdefects on the (100) surface.

  11. Multiband enhanced absorption of monolayer graphene with attenuated total reflectance configuration and sensing application

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Bu, Lingbing; Chen, Yunyun; Zheng, Gaige; Zou, Xiujuan; Xu, Linhua; Wang, Jicheng

    2017-01-01

    An enhanced absorption of monolayer graphene is obtained in a multilayer film-based attenuated total reflectance configuration in the visible wavelength range. The enhanced absorption under transverse magnetic and electric conditions is associated with the excitation of the waveguide mode in the thin-film layer, which is verified by the numerical calculation of field profiles. The obtained results manifest that the model induces a high field enhancement at the graphene-dielectric interface with the resonant angle, which implies potential sensing applications. The magnitude of the figure of merit is found to be three times higher than that of a conventional surface plasmon sensor.

  12. Preliminary Method for Direct Quantification of Colistin Methanesulfonate by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

    PubMed Central

    Niece, Krista L.

    2015-01-01

    Colistin use has increased in response to the advent of infections caused by multidrug-resistant organisms. It is administered parenterally as an inactive prodrug, colistin methanesulfonate (CMS). Various formulations of CMS and labeling conventions can lead to confusion about colistin dosing, and questions remain about the pharmacokinetics of CMS. Since CMS does not have strong UV absorbance, current methods employ a laborious process of chemical conversion to colistin followed by precolumn derivatization to detect formed colistin by high-performance liquid chromatography. Here, we report a method for direct quantification of colistin methanesulfonate by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR). PMID:26124160

  13. Thin-film absorption coefficients by attenuated-total-reflection spectroscopy.

    PubMed

    Holm, R T; Palik, E D

    1978-02-01

    The application of attenuated-total-reflection spectroscopy to the measurement of the absorption coefficient of thin films is presented. For low absorption the sensitivity of ATR is discussed in terms of the concept of an effective thickness. Both the case in which the refractive index of the film is higher and the case in which it is lower than that of the ATR trapezoid are considered. Experimental ATR data for antireflection-coating materials for laser windows is analyzed and compared with calorimetric data.

  14. Study of ester crosslinking reactions on aluminum surfaces by infrared attenuated total reflectance spectrometry

    NASA Astrophysics Data System (ADS)

    Bhat, Sanmitra A.; Yang, Charles Q.; de Haseth, James A.

    1998-06-01

    Polycarboxylic acids are used as an alternative nonformaldehyde durable press finishing agents for cotton fabrics. Previous studies have shown that polycarboxylic acids esterify with cotton cellulose through intermediate formation of a cyclic anhydride. Cotton cellulose, due to the presence of hydroxyl groups, is a very active substrate. To understand the mechanism of ester formation, esterification reactions were studied on aluminum surfaces by infrared attenuated total reflectance (ATR) spectrometry. The infrared data showed that a five-membered cyclic anhydride is formed as an intermediate, that esterifies with the crosslinking agents. The data also demonstrated that formation of anhydride increases with temperature and also in the presence of a catalyst.

  15. Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite

    NASA Astrophysics Data System (ADS)

    Aufort, Julie; Ségalen, Loïc; Gervais, Christel; Brouder, Christian; Balan, Etienne

    2016-10-01

    Attenuated total reflectance (ATR) infrared spectra were measured on a synthetic and a natural fluorapatite sample. A modeling approach based on the computation of the Fresnel reflection coefficient between the ATR crystal and the powder sample was used to analyze the line shape of the spectra. The dielectric properties of the samples were related to those of pure fluorapatite using an effective medium approach, based on Maxwell-Garnett and Bruggeman models. The Bruggeman effective medium model leads to a very good agreement with the experimental data recorded on the synthetic fluorapatite sample. The poorer agreement observed on the natural sample suggests a more significant heterogeneity of the sample at a characteristic length scale larger than the mid-infrared characteristic wavelength, i.e., about 10 micrometers. The results demonstrate the prominent role of macroscopic electrostatic effects over fine details of the microscopic structure in determining the line shape of strong ATR bands.

  16. Mix ratio measurements of pozzolanic blends by Fourier transform infrared-attenuated total reflectance method

    SciTech Connect

    Rebagay, T.V.; Dodd, D.A.

    1992-07-01

    The disposal of low-level radioactive liquid wastes at the Hanford Site near Richland, Washington, involves mixing the wastes with pozzolanic grout-forming solid blends. Checking the quality of each blend component and its mix ratio will ensure processibility of the blend and the long-term performance of the resulting waste grout. In earlier work at Hanford laboratories, Fourier transform infrared-transmission method (FTIR-TR) using KBr pellet was applied successfully in the analysis of blends consisting of cement, fly ash, and clays. This method involves time-consuming sample preparation resulting in slow turnaround for repetitive sampling. Because reflection methods do not require elaborate sample preparation, they have the potential to reduce turnaround analysis time. Neat samples may be examined making these methods attractive for quality control. This study investigates the capability of Fourier transform infrared-attenuated total reflectance method (FTIR-ATR) to analyze pozzolanic blends.

  17. Midinfrared spectroscopy of synthetic olivines: Thermal emission, specular and diffuse reflectance, and attenuated total reflectance studies of forsterite to fayalite

    NASA Astrophysics Data System (ADS)

    Lane, Melissa D.; Glotch, Timothy D.; Dyar, M. Darby; Pieters, Carle M.; Klima, Rachel; Hiroi, Takahiro; Bishop, Janice L.; Sunshine, Jessica

    2011-08-01

    Synthetic olivine samples ranging in composition from forsterite to fayalite are analyzed in the midinfrared using thermal emission, specular and diffuse reflectance, and attenuated total reflectance spectroscopies to study the spectral effects of Mg-Fe solid solution. For each method, fundamental bands gradually change in position and strength from Mg2SiO4 at larger wave numbers to Fe2SiO4 at smaller wave numbers. Each spectrum is diagnostic of chemistry within the continuum, as previously noted. In this study, 10 identified fundamental bands are traceable across the solid solution series for each technique. In pelletized sample spectra, the 10 bands shift approximately linearly in position by as little as 11 to as much as 64 cm-1. In powdered sample spectra, the bands shift by as little as 12 to as much as 74 cm-1 (disregarding one outlier point). Moreover, for every spectral technique, an even larger linear shift is identified of a specific emissivity maximum/reflectivity minimum (the flection position). From forsterite to fayalite, this flection position shifts by at least 88 cm-1, which is, on average, 48% more than the largest fundamental band shift within the same data set for the pelletized spectra and 44% more for the powdered spectra. Also the R2 and 2σ values of the best fit line for the flection position shift (versus Fo#) generally were as good as or routinely better than those of the fundamental bands. Thus, the flection position should be considered as a means of determining Mg-Fe olivine composition when using thermal emission, specular reflectance, diffuse reflectance, or attenuated total reflectance spectroscopic data.

  18. Applications of microstructured silicon wafers as internal reflection elements in attenuated total reflection Fourier transform infrared spectroscopy.

    PubMed

    Schumacher, Henrik; Künzelmann, Ulrich; Vasilev, Boris; Eichhorn, Klaus-Jochen; Bartha, Johann W

    2010-09-01

    A novel internal reflection element (IRE) for attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectral acquisition is introduced and applied for several surface-sensitive measurements. It is based on microstructured double-side-polished (100) silicon wafers with v-shaped grooves of {111} facets on their backside. These facets of the so-called "microstructured single-reflection elements" (mSRE) are formed by a crystal-oriented anisotropic wet etching process within a conventional wafer structuring process. They are used to couple infrared radiation into and out of the IRE. In contrast to the application of the commonly used silicon multiple-reflection elements (MRE), the new elements provide single-reflection ATR measurements at the opposite wafer side by using simple reflection accessories without any special collimation. Due to the short light path, the spectral range covers the entire mid-infrared region with a high optical throughput, including the range of silicon lattice vibrations from 300 to 1500 cm(-1). In addition to typical ATR applications, i.e., the measurement of bulk liquids and soft materials, the new reflection elements can be effectively used and customer-specifically designed for in situ and ex situ investigations of aqueous solutions, thin films, and monolayers on Si. Examples presented in this article are in situ etching of native as well as thermal SiO(2) and characterization of polydimethylsiloxane (PDMS) films on Si under various measuring conditions.

  19. Attenuated total reflectance powder cell for infrared analysis of hygroscopic samples.

    PubMed

    Lekgoathi, M D S; le Roux, J P

    2011-11-01

    An attenuated total reflectance (ATR) sample cell has been designed, manufactured and subsequently used for the mid-infrared analysis of hygroscopic samples. This sample cell was installed as a simple drop-in replacement for the cell supplied with our commercially available Harrick Mvp-Pro FTIR-ATR accessory. Calcium chloride, a well-known desiccant that has a propensity to absorb water into its crystal lattice, was selected as non-infrared active substrate to accentuate the efficacy of the cell in preserving the anhydrous state of the sample by straightforward monitoring of the water bands. In contrast, mid-infrared spectra are presented that qualitatively demonstrate the rapid rate at which atmospheric moisture is incorporated into the anhydrous sample when analyzed using the conventional ATR cell assembly.

  20. Infrared Attenuated Total Reflectance Spectroscopy: An Innovative Strategy for Analyzing Mineral Components in Energy Relevant Systems

    NASA Astrophysics Data System (ADS)

    Müller, Christian Menno; Pejcic, Bobby; Esteban, Lionel; Piane, Claudio Delle; Raven, Mark; Mizaikoff, Boris

    2014-10-01

    The direct qualitative and quantitative determination of mineral components in shale rocks is a problem that has not been satisfactorily resolved to date. Infrared spectroscopy (IR) is a non-destructive method frequently used in mineral identification, yet challenging due to the similarity of spectral features resulting from quartz, clay, and feldspar minerals. This study reports on a significant improvement of this methodology by combining infrared attenuated total reflection spectroscopy (IR-ATR) with partial least squares (PLS) regression techniques for classifying and quantifying various mineral components present in a number of different shale rocks. The developed multivariate classification model was calibrated using pure component mixtures of the most common shale minerals (i.e., kaolinite, illite, montmorillonite, calcite, and quartz). Using this model, the IR spectra of 11 real-world shale samples were analyzed and evaluated. Finally, the performance of the developed IR-ATR method was compared with results obtained via X-ray diffraction (XRD) analysis.

  1. Infrared attenuated total reflectance spectroscopy: an innovative strategy for analyzing mineral components in energy relevant systems.

    PubMed

    Müller, Christian Menno; Pejcic, Bobby; Esteban, Lionel; Delle Piane, Claudio; Raven, Mark; Mizaikoff, Boris

    2014-10-31

    The direct qualitative and quantitative determination of mineral components in shale rocks is a problem that has not been satisfactorily resolved to date. Infrared spectroscopy (IR) is a non-destructive method frequently used in mineral identification, yet challenging due to the similarity of spectral features resulting from quartz, clay, and feldspar minerals. This study reports on a significant improvement of this methodology by combining infrared attenuated total reflection spectroscopy (IR-ATR) with partial least squares (PLS) regression techniques for classifying and quantifying various mineral components present in a number of different shale rocks. The developed multivariate classification model was calibrated using pure component mixtures of the most common shale minerals (i.e., kaolinite, illite, montmorillonite, calcite, and quartz). Using this model, the IR spectra of 11 real-world shale samples were analyzed and evaluated. Finally, the performance of the developed IR-ATR method was compared with results obtained via X-ray diffraction (XRD) analysis.

  2. Rapid analysis of tetracycline hydrochloride solution by attenuated total reflection terahertz time-domain spectroscopy.

    PubMed

    Qin, Jianyuan; Xie, Lijuan; Ying, Yibin

    2017-06-01

    Despite numerous methods for the detection of antibiotic residues, they are usually destructive and require tedious pre-treatment. Terahertz time-domain spectroscopy (THz-TDS) is an emerging technology that has advantages for analyzing chemical and biological compounds since THz waves are very sensitive to the molecular vibrational modes. Here we incorporated attenuated total reflection technique into the THz-TDS and demonstrated that this technology (ATR THz-TDS) allowed to determine the complex refractive indices of tetracycline hydrochloride (TCH) solutions with high accuracy and could be used to predict their concentrations. Our results from the simple linear regression models indicated that the complex refractive index exhibited a monotonic decrease with an increase in the TCH concentration. This study will provide new knowledge about the concentration determination of a liquid sample that couldn't be elucidated with the conventional THz-TDS technologies.

  3. An attenuated total reflectance mid infrared (ATR-MIR) spectroscopy study of gelatinization in barley.

    PubMed

    Cozzolino, D; Roumeliotis, S; Eglinton, J

    2014-08-08

    The aim of this study was to evaluate the use of attenuated total reflectance and mid infrared (ATR-MIR) spectroscopy and to understand the gelatinization and retro-gradation of flour barley samples and the relationship with malting quality. Samples were sourced from two commercial barley varieties exhibiting high hot water extract (HWE) namely Navigator (n=8), and Admiral (n=8). Samples were analysed using the Rapid Visco Analyser (RVA) and ATR-MIR analysis. These results showed that ATR-MIR spectroscopy is capable of characterising gel samples derived from barley flour samples having different malting characteristics. Infrared spectra can effectively represent a 'fingerprint' of the sample being analysed and can be used to simplify and reduce analytical times in the routine methods currently used. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Evidence of light depolarization in grazing incidence germanium attenuated total reflection prisms.

    PubMed

    Rochat, Névine; Klymko, Nancy; Licitra, Christophe; Gambacorti, Narciso

    2011-09-01

    Attenuated total reflection (ATR) infrared absorption spectroscopy is a well-known vibrational spectroscopy technique for many different applications. In recent years this technique has been used to detect thin layer(s) lying on a solid substrate. Such a sample needs high pressure to ensure good optical contact between sample and prism and a p-polarization to enhance the signal to be detected. Such conditions have not been detailed in the literature regarding the effect of high pressure on the ATR measurement. This study shows the detrimental effect of high pressure on the ATR spectra. This effect is related to light depolarization induced by the germanium prism under high pressure. Moreover, the importance of polarizer position in the optical bench is highlighted. Indeed, due to the pressure-induced depolarization of the prism, the polarizer has to be placed before the prism to limit undesirable effects on the ATR spectrum baseline.

  5. Detection of whitening agents in illegal cosmetics using attenuated total reflectance-infrared spectroscopy.

    PubMed

    Deconinck, E; Bothy, J L; Desmedt, B; Courselle, P; De Beer, J O

    2014-09-01

    Cosmetic products containing illegal whitening agents are still found on the European market. They represent a considerable risk to public health, since they are often characterised by severe side effects when used chronically. The detection of such products at customs is not always simple, due to misleading packaging and the existence of products containing only legal components. Therefore there is a need for easy to use equipment and techniques to perform an initial screening of samples. The use of attenuated total reflectance-infrared (ATR-IR) spectroscopy, combined with chemometrics, was evaluated for that purpose. It was found that the combination of ATR-IR with the simple chemometric technique k-nearest neighbours gave good results. A model was obtained in which a minimum of illegal samples was categorised as legal. The correctly classified illegal samples could be attributed to the illegal components present.

  6. Attenuated total reflectance Fourier transform infrared spectroscopy analysis of red seal inks on questioned document.

    PubMed

    Nam, Yun Sik; Park, Jin Sook; Kim, Nak-Kyoon; Lee, Yeonhee; Lee, Kang-Bong

    2014-07-01

    Seals are traditionally used in the Far East Asia to stamp an impression on a document in place of a signature. In this study, an accuser claimed that a personal contract regarding mining development rights acquired by a defendant was devolved to the accuser because the defendant stamped the devolvement contract in the presence of the accuser and a witness. The accuser further stated that the seal ink stamped on the devolvement contract was the same as that stamped on the development rights application document. To verify this, the seals used in two documents were analyzed using micro-attenuated total reflectance Fourier transform infrared spectroscopy and infrared spectra. The findings revealed that the seals originated from different manufacturers. Thus, the accuser's claim on the existence of a devolvement contract was proved to be false.

  7. Minimally invasive screening for colitis using attenuated total internal reflectance fourier transform infrared spectroscopy.

    PubMed

    Titus, Jitto; Viennois, Emilie; Merlin, Didier; Unil Perera, A G

    2017-03-01

    This article describes a rapid, simple and cost-effective technique that could lead to a screening method for colitis without the need for biopsies or in vivo measurements. This screening technique includes the testing of serum using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy for the colitis-induced increased presence of mannose. Chronic (Interleukin 10 knockout) and acute (Dextran Sodium Sulphate-induced) models for colitis are tested using the ATR-FTIR technique. Arthritis (Collagen Antibody Induced Arthritis) and metabolic syndrome (Toll like receptor 5 knockout) models are also tested as controls. The marker identified as mannose uniquely screens and distinguishes the colitic from the non-colitic samples and the controls. The reference or the baseline spectrum could be the pooled and averaged spectra of non-colitic samples or the subject's previous sample spectrum. This shows the potential of having individualized route maps of disease status, leading to personalized diagnosis and drug management.

  8. Quantitative Analysis of Alcohol, Sugar, and Tartaric Acid in Alcoholic Beverages Using Attenuated Total Reflectance Spectroscopy

    PubMed Central

    Nagarajan, R.; Gupta, A.; Bajaj, M. M.

    2006-01-01

    Mid-infrared (MIR) spectroscopy in attenuated total reflectance (ATR) mode was used for quantifying ethanol, sucrose, and tartaric acid in alcoholic beverages. One hundred synthetic samples were prepared with different ethanol, sucrose, and tartaric acid concentrations. Experiments were carried out on Bio-Rad 175 C FTS using an ATR accessory. Spectra were recorded in the wavelength region 600–4000 cm −1 . Calibration was performed using partial least squares (PLS) algorithm. Commercially available alcoholic beverages (gin, rum, vodka, etc.) were experimented and concentration of ethanol in these samples was predicted using the developed calibration model. Chemical analysis of these commercial samples was carried out in order to compare the results. The agreement between ATR results with those of chemical analysis revealed good reliability and repeatability of the technique used. PMID:17671618

  9. Studying substrate binding to reconstituted secondary transporters by attenuated total reflection infrared difference spectroscopy.

    PubMed

    Lórenz-Fonfría, Víctor A; León, Xavier; Padrós, Esteve

    2012-01-01

    The determination of protein conformational changes induced by the interaction of substrates with secondary transporters is an important step toward the elucidation of their transport mechanism. Since conformational changes in a protein alter its vibrational patterns, they can be detected with high sensitivity by infrared difference (IR(diff)) spectroscopy without the need for external probes. We describe a general procedure to obtain substrate-induced IR(diff) spectra by alternating perfusion of buffers over an attenuated total reflection (ATR) crystal containing an adhered film of a membrane protein reconstituted in lipids. As an example, we provide specific protocols to obtain melibiose and Na(+)-induced ATR-IR(diff) spectra of reconstituted melibiose permease, a sodium/melibiose co-transporter from E. coli. The presented methodology is applicable in principle to any membrane protein, provided that it can be purified and reconstituted in functional form, and appropriate substrates are available.

  10. Attenuated total reflectance spectroscopy of plant leaves: A tool for ecological and botanical studies

    USGS Publications Warehouse

    Ribeiro da Luz, B.

    2006-01-01

    ??? Attenuated total reflectance (ATR) spectra of plant leaves display complex absorption features related to organic constituents of leaf surfaces. The spectra can be recorded rapidly, both in the field and in the laboratory, without special sample preparation. ??? This paper explores sources of ATR spectral variation in leaves, including compositional, positional and temporal variations. Interspecific variations are also examined, including the use of ATR spectra as a tool for species identification. ??? Positional spectral variations generally reflected the abundance of cutin and the epicuticular wax thickness and composition. For example, leaves exposed to full sunlight commonly showed more prominent cutin- and wax-related absorption features compared with shaded leaves. Adaxial vs. abaxial leaf surfaces displayed spectral variations reflecting differences in trichome abundance and wax composition. Mature vs. young leaves showed changes in absorption band position and intensity related to cutin, polysaccharide, and possibly amorphous silica development on and near the leaf surfaces. ??? Provided that similar samples are compared (e.g. adaxial surfaces of mature, sun-exposed leaves) same-species individuals display practically identical ATR spectra. Using spectral matching procedures to analyze an ATR database containing 117 individuals, including 32 different tree species, 83% of the individuals were correctly identified. ?? The Authors (2006).

  11. Pressure-modulation dynamic attenuated-total-reflectance (ATR) FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Marcott, C.; Story, G. M.; Noda, I.; Bibby, A.; Manning, C. J.

    1998-06-01

    A single-reflectance attenuated-total-reflectance (ATR) accessory with a diamond internal-reflection element was modified by the addition of a piezoelectric transducer. Initial dynamic pressure-modulation experiments have been performed in the sample compartment of a step-scanning FT-IR spectrometer. A sinusoidal pressure modulation applied to samples of isotactic polypropylene and linear low density polyethylene resulted in dynamic responses which appear to be similar to those observed in previous dynamic 2D IR experiments. Preliminary pressure-modulation dynamic ATR results are also reported for a styrene-butadiene-styrene triblock copolymer. The new method has the advantages that a much wider variety of sample types and geometries can be studied and less sample preparation is required. Dynamic 2D IR experiments carried out by ATR no longer require thin films of large area and sufficient strength to withstand the dynamic strain applied by a rheometer. The ability to obtain dynamic IR spectroscopic information from a wider variety of sample types and thicknesses would greatly expand the amount of useful information that could be extracted from normally complicated, highly overlapped IR spectra.

  12. [Fast determination of induction period of motor gasoline using Fourier transform attenuated total reflection infrared spectroscopy].

    PubMed

    Liu, Ya-Fei; Yuan, Hong-Fu; Song, Chun-Feng; Xie, Jin-Chun; Li, Xiao-Yu; Yan, De-Lin

    2014-11-01

    A new method is proposed for the fast determination of the induction period of gasoline using Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR). A dedicated analysis system with the function of spectral measurement, data processing, display and storage was designed and integrated using a Fourier transform infrared spectrometer module and chemometric software. The sample presentation accessory designed which has advantages of constant optical path, convenient sample injection and cleaning is composed of a nine times reflection attenuated total reflectance (ATR) crystal of zinc selenide (ZnSe) coated with a diamond film and a stainless steel lid with sealing device. The influence of spectral scanning number and repeated sample loading times on the spectral signal-to-noise ratio was studied. The optimum spectral scanning number is 15 times and the optimum sample loading number is 4 times. Sixty four different gasoline samples were collected from the Beijing-Tianjin area and the induction period values were determined as reference data by standard method GB/T 8018-87. The infrared spectra of these samples were collected in the operating condition mentioned above using the dedicated fast analysis system. Spectra were pretreated using mean centering and 1st derivative to reduce the influence of spectral noise and baseline shift A PLS calibration model for the induction period was established by correlating the known induction period values of the samples with their spectra. The correlation coefficient (R2), standard error of calibration (SEC) and standard error of prediction (SEP) of the model are 0.897, 68.3 and 91.9 minutes, respectively. The relative deviation of the model for gasoline induction period prediction is less than 5%, which meets the requirements of repeatability tolerance in GB method. The new method is simple and fast. It takes no more than 3 minutes to detect one sample. Therefore, the method is feasible for implementing

  13. Characterization of historic silk by polarized attenuated total reflectance Fourier transform infrared spectroscopy for informed conservation.

    PubMed

    Garside, Paul; Lahlil, Sophia; Wyeth, Paul

    2005-10-01

    When assessing historic textiles and considering appropriate conservation, display, and storage strategies, characterizing the physical condition of the textiles is essential. Our work has concentrated on developing nondestructive or micro-destructive methodologies that will permit this. Previously, we have demonstrated a correlation between the physical deterioration of unweighted and "pink" tin (IV) chloride weighted silk and certain measurable spectroscopic and chromatographic signatures, derived from polarized Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy (Pol-ATR) and high-performance liquid chromatography (HPLC) microsampling analyses. The application of the Pol-ATR technique to aged silk characterization has now been extended to include a more comprehensive range of weighting methods and aging regimes. This was intended to replicate the full spectrum of states of deterioration observed in silk textiles, from pristine to heavily degraded. Breaking strength was employed as a measure of the physical integrity of the fibers, and, as expected, decreased with aging. An orientational crystallinity parameter, reflecting the microstructural ordering of the fibroin polymer within the fibers, was derived from the Pol-ATR spectra. A good correlation was observed between the breaking strength of the variety of fibers and this parameter. This suggests that the physical state of historic silk fabrics might be adequately characterized for conservation purposes by such indirect micromethodology.

  14. Discrimination of Alicyclobacillus strains using nitrocellulose membrane filter and attenuated total reflectance fourier transform infrared spectroscopy.

    PubMed

    Wang, Jun; Yue, Tianli; Yuan, Yahong; Lu, Xiaonan; Shin, Joong-Han; Rasco, Barbara

    2011-03-01

    Alicyclobacillus spp. are thermoacidophilic, spore-forming bacteria, some of which cause spoilage in pasteurized and heat-treated apple juice products through the production of guaiacol. It would be helpful if a rapid method to detect and discriminate Alicyclobacillus strains was available. A simple and rapid sample preparation method using nitrocellulose membrane filter (NMF) and a single reflection horizontal attenuated total reflection (HATR) accessory with Fourier transform infrared (FT-IR) was developed here. Fourier transform infrared (FT-IR) spectroscopy was used and tested on 8 Alicyclobacillus strains (KF, WAC, NWN-13501, NWN-12697, NWN-12654, NWN-10682, 1016, 1101). A linear discriminant analysis (LDA) was established to discriminate Alicyclobacillus strains. The sample preparation method could successfully separated strains into different groups by principal component analysis (PCA). High identification accuracy (95%) was achieved with the LDA model. The method developed in the paper can be used to discriminate different Alicyclobacillus strains from each other making it possible to easily determine whether the strain of Alicyclobacillus present is associated with juice spoilage.

  15. Glucose quantification in dried-down nanoliter samples using mid-infrared attenuated total reflection spectroscopy.

    PubMed

    Diessel, Edgar; Willmann, Stefan; Kamphaus, Peter; Kurte, Roland; Damm, Uwe; Heise, H Michael

    2004-04-01

    The aim of this study was to determine the feasibility of minimally invasive glucose concentration measurement of a body fluid within the physiologically important range below 100 nL with a number of samples such as interstitial fluid, plasma, or whole blood using mid-infrared spectroscopy, but starting with preliminary measurements on samples of simple aqueous glucose solutions. The Fourier transform infrared spectrometer was equipped with a Golden Gate single reflection diamond attenuated total reflection (ATR) accessory and a room-temperature pyroelectric detector. As the necessary detection limits can be achieved only for dried samples within the spectrometric conditions realized by a commercial instrument, the work focused on the optimization of such ATR measurements. We achieved quantification of samples with volumes as low as 7 nL between 10 and 600 mg/dL. The standard error of prediction (SEP) for the concentration range 10-100 mg/dL is 3.2 mg/dL with full interval data between 1180 and 940 cm(-1). The performance of the prediction is given by a coefficient of variation of prediction (CV(pred) ) of 6.2%. When all samples within the whole concentration range are included, the SEP increases to 20.2 mg/dL, and hence the CV(pred) to 10.6% due to a nonlinear signal dependence on glucose concentration. A detection limit for glucose of 0.7 ng with a signal-to-noise ratio of 10 was obtained.

  16. Simulation of attenuated total reflection infrared absorbance spectra: applications to automotive clear coat forensic analysis.

    PubMed

    Lavine, Barry K; Fasasi, Ayuba; Mirjankar, Nikhil; Nishikida, Koichi; Campbell, Jay

    2014-01-01

    Attenuated total reflection (ATR) is a widely used sampling technique in infrared (IR) spectroscopy because minimal sample preparation is required. Since the penetration depth of the ATR analysis beam is quite shallow, the outer layers of a laminate or multilayered paint sample can be preferentially analyzed with the entire sample intact. For this reason, forensic laboratories are taking advantage of ATR to collect IR spectra of automotive paint systems that may consist of three or more layers. However, the IR spectrum of a paint sample obtained by ATR will exhibit distortions, e.g., band broadening and lower relative intensities at higher wavenumbers, compared with its transmission counterpart. This hinders library searching because most library spectra are measured in transmission mode. Furthermore, the angle of incidence for the internal reflection element, the refractive index of the clear coat, and surface contamination due to inorganic contaminants can profoundly influence the quality of the ATR spectrum obtained for automotive paints. A correction algorithm to allow ATR spectra to be searched using IR transmission spectra of the paint data query (PDQ) automotive database is presented. The proposed correction algorithm to convert transmission spectra from the PDQ library to ATR spectra is able to address distortion issues such as the relative intensities and broadening of the bands, and the introduction of wavelength shifts at lower frequencies, which prevent library searching of ATR spectra using archived IR transmission data.

  17. Discrimination between immature and mature green coffees by attenuated total reflectance and diffuse reflectance Fourier transform infrared spectroscopy.

    PubMed

    Craig, Ana Paula; Franca, Adriana S; Oliveira, Leandro S

    2011-10-01

    The objective of this work was to evaluate the potential of Fourier transform infrared spectroscopy (FTIR) in the characterization and discrimination between immature and mature or ripe coffee beans. Arabica coffee beans were submitted to FTIR analysis by reflectance readings employing attenuated total reflectance (ATR) and diffuse reflectance (DR) accessories. The obtained spectra were similar, but in general higher absorbance values were observed for nondefective beans in comparison to immature ones. Multivariate statistical analysis (principal component analysis, PCA, and agglomerative hierarchical clustering, AHC) was performed in order to verify the possibility of discrimination between immature and mature coffee samples. A clear separation between immature and mature coffees was observed based on AHC and PCA analyses of the normalized spectra obtained by employing both ATR and DR accessories. Linear discriminant analysis was employed for developing classification models, with recognition and prediction abilities of 100%. Such results showed that FTIR analysis presents potential for the development of a simple routine methodology for separation of immature and mature coffee beans. Practical Application: The ultimate goal of this research is to be able to propose improvements in the way immature coffee beans are separated from graded mature beans in coffee facilities (cooperatives and other coffee producer's associations). The results obtained herein point toward FTIR as a potential tool for the aimed improvements.

  18. Characterization of Printing Inks Using DART-Q-TOF-MS and Attenuated Total Reflectance (ATR) FTIR.

    PubMed

    Williamson, Rhett; Raeva, Anna; Almirall, Jose R

    2016-05-01

    The rise in improved and widely accessible printing technology has resulted in an interest to develop rapid and minimally destructive chemical analytical techniques that can characterize printing inks for forensic document analysis. Chemical characterization of printing inks allows for both discrimination of inks originating from different sources and the association of inks originating from the same source. Direct analysis in real-time mass spectrometry (DART-MS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were used in tandem to analyze four different classes of printing inks: inkjets, toners, offset, and intaglio. A total of 319 samples or ~ 80 samples from each class were analyzed directly on a paper substrate using the two methods. DART-MS was found to characterize the semi-volatile polymeric vehicle components, while ATR-FTIR provided chemical information associated with the bulk components of these inks. Complimentary data results in improved discrimination when both techniques are used in succession resulting in >96% discrimination for all toners, 95% for all inkjets, >92% for all offset, and >54% for all intaglio inks. © 2016 American Academy of Forensic Sciences.

  19. Attenuated total reflectance-FT-IR spectroscopy for gunshot residue analysis: potential for ammunition determination.

    PubMed

    Bueno, Justin; Sikirzhytski, Vitali; Lednev, Igor K

    2013-08-06

    The ability to link a suspect to a particular shooting incident is a principal task for many forensic investigators. Here, we attempt to achieve this goal by analysis of gunshot residue (GSR) through the use of attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR) combined with statistical analysis. The firearm discharge process is analogous to a complex chemical process. Therefore, the products of this process (GSR) will vary based upon numerous factors, including the specific combination of the firearm and ammunition which was discharged. Differentiation of FT-IR data, collected from GSR particles originating from three different firearm-ammunition combinations (0.38 in., 0.40 in., and 9 mm calibers), was achieved using projection to latent structures discriminant analysis (PLS-DA). The technique was cross (leave-one-out), both internally and externally, validated. External validation was achieved via assignment (caliber identification) of unknown FT-IR spectra from unknown GSR particles. The results demonstrate great potential for ATR-FT-IR spectroscopic analysis of GSR for forensic purposes.

  20. Attenuated total reflectance-FT-IR imaging for rapid and automated detection of gunshot residue.

    PubMed

    Bueno, Justin; Lednev, Igor K

    2014-04-01

    An alternative approach for the nondestructive, rapid and selective detection of gunshot residue (GSR) was investigated. A cloth substrate containing GSR particles expelled during a firearm discharge was used as an analog for the clothing of a shooting victim or a suspect discharging a firearm. An established and efficient procedure for GSR collection (tape lifting) was utilized to recover GSR particles from the cloth substrate. Microscopic-attenuated total reflectance (ATR) Fourier transform (FT) infrared (IR) spectroscopic imaging rapidly and automatically scanned large areas of the tape collection substrate and detected varying morphologies (microscopic and macroscopic) and chemical compositions (organic and inorganic) of GSR. The "spectroscopic fingerprint" of each GSR type provided unique virbrational modes, which were not characteristic of the tape collection substrate or the cloth debris which was also recovered. ATR images (maps) targeted the detection of these unique chemical markers over the mapped area. The hues of the ATR images were determined by the intensity of the signal for the chemical marker of each analyte. The spatial resolution of the technique was determined to be 4.7 μm. Therefore, all GSR particles sized 4.7 μm or larger will be resolved and detected on the tape substrate using micro-ATR imaging.

  1. Detection of citrus Huanglongbing by Fourier transform infrared-attenuated total reflection spectroscopy.

    PubMed

    Hawkins, Samantha A; Park, Bosoon; Poole, Gavin H; Gottwald, Timothy; Windham, William R; Lawrence, Kurt C

    2010-01-01

    Citrus Huanglongbing (HLB, also known as citrus greening disease) was discovered in Florida in 2005 and is spreading rapidly amongst the citrus growing regions of the state. Detection via visual symptoms of the disease is not a long-term viable option. New techniques are being developed to test for the disease in its earlier presymptomatic stages. Fourier transform infrared-attenuated total reflection (FT-IR-ATR) spectroscopy is a candidate for rapid, inexpensive, early detection of the disease. The mid-infrared region of the spectrum reveals dramatic changes that take place in the infected leaves when compared to healthy non-infected leaves. The carbohydrates that give rise to peaks in the 900-1180 cm(-1) range are reliable in distinguishing leaves from infected plants versus non-infected plants. A model based on chemometrics was developed using the spectra from 179 plants of known disease status. This model then correctly predicted the status of >95% of the plants tested.

  2. Attenuated Total Internal Reflectance Infrared Spectroscopy (ATR-FTIR): A Quantitative Approach for Kidney Stone Analysis

    PubMed Central

    Gulley-Stahl, Heather J.; Haas, Jennifer A.; Schmidt, Katherine A.; Evan, Andrew P.; Sommer, André J.

    2011-01-01

    The impact of kidney stone disease is significant worldwide, yet methods for quantifying stone components remain limited. A new approach requiring minimal sample preparation for the quantitative analysis of kidney stone components has been investigated utilizing attenuated total internal reflectance infrared spectroscopy (ATR-FTIR). Calcium oxalate monohydrate (COM) and hydroxylapatite (HAP), two of the most common constituents of urinary stones, were used for quantitative analysis. Calibration curves were constructed using integrated band intensities of four infrared absorptions versus concentration (weight %). The correlation coefficients of the calibration curves range from 0.997 to 0.93. The limits of detection range from 0.07 ± 0.02% COM/HAP where COM is the analyte and HAP the matrix to 0.26 ± 0.07% HAP/COM where HAP is the analyte and COM the matrix. This study shows that linear calibration curves can be generated for the quantitative analysis of stone mixtures provided the system is well understood especially with respect to particle size. PMID:19589213

  3. Early detection of cell activation events by means of attenuated total reflection Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Titus, Jitto; Filfili, Chadi; Hilliard, Julia K.; Ward, John A.; Unil Perera, A. G.

    2014-06-01

    Activation of Jurkat T-cells in culture following treatment with anti-CD3 (Cluster of Differentiation 3) antibody is detectable by interrogating the treated T-cells using the Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) Spectroscopy technique. Cell activation was detected within 75 min after the cells encountered specific immunoglobulin molecules. Spectral markers noted following ligation of the CD3 receptor with anti CD3 antibody provides proof-of-concept that ATR-FTIR spectroscopy is a sensitive measure of molecular events subsequent to cells interacting with anti-CD3 Immunoglobulin G. The resultant ligation of the CD3 receptor results in the initiation of well defined, specific signaling pathways that parallel the measurable molecular events detected using ATR-FTIR. Paired t-test with post-hoc Bonferroni corrections for multiple comparisons has resulted in the identification of statistically significant spectral markers (p < 0.02) at 1367 and 1358 cm-1. Together, these data demonstrate that early treatment-specific cellular events can be measured by ATR-FTIR and that this technique can be used to identify specific agents via the responses of the cell biosensor at different time points postexposure.

  4. Quantitative orientation measurements in thin lipid films by attenuated total reflection infrared spectroscopy.

    PubMed Central

    Picard, F; Buffeteau, T; Desbat, B; Auger, M; Pézolet, M

    1999-01-01

    Quantitative orientation measurements by attenuated total reflectance (ATR) infrared spectroscopy require the accurate knowledge of the dichroic ratio and of the mean-square electric fields along the three axes of the ATR crystal. In this paper, polarized ATR spectra of single supported bilayers of the phospholipid dimyristoylphosphatidic acid covered by either air or water have been recorded and the dichroic ratio of the bands due to the methylene stretching vibrations has been calculated. The mean-square electric field amplitudes were calculated using three formalisms, namely the Harrick thin film approximation, the two-phase approximation, and the thickness- and absorption-dependent one. The results show that for dry bilayers, the acyl chain tilt angle varies with the formalism used, while no significant variations are observed for the hydrated bilayers. To test the validity of the different formalisms, s- and p-polarized ATR spectra of a 40-A lipid layer were simulated for different acyl chain tilt angles. The results show that the thickness- and absorption-dependent formalism using the mean values of the electric fields over the film thickness gives the most accurate values of acyl chain tilt angle in dry lipid films. However, for lipid monolayers or bilayers, the tilt angle can be determined with an acceptable accuracy using the Harrick thin film approximation. Finally, this study shows clearly that the uncertainty on the determination of the tilt angle comes mostly from the experimental error on the dichroic ratio and from the knowledge of the refractive index. PMID:9876167

  5. Correcting attenuated total reflection-Fourier transform infrared spectra for water vapor and carbon dioxide.

    PubMed

    Bruun, Susanne W; Kohler, Achim; Adt, Isabelle; Sockalingum, Ganesh D; Manfait, Michel; Martens, Harald

    2006-09-01

    Fourier transform infrared (FT-IR) spectroscopy is a valuable technique for characterization of biological samples, providing a detailed fingerprint of the major chemical constituents. However, water vapor and CO(2) in the beam path often cause interferences in the spectra, which can hamper the data analysis and interpretation of results. In this paper we present a new method for removal of the spectral contributions due to atmospheric water and CO(2) from attenuated total reflection (ATR)-FT-IR spectra. In the IR spectrum, four separate wavenumber regions were defined, each containing an absorption band from either water vapor or CO(2). From two calibration data sets, gas model spectra were estimated in each of the four spectral regions, and these model spectra were applied for correction of gas absorptions in two independent test sets (spectra of aqueous solutions and a yeast biofilm (C. albicans) growing on an ATR crystal, respectively). The amounts of the atmospheric gases as expressed by the model spectra were estimated by regression, using second-derivative transformed spectra, and the estimated gas spectra could subsequently be subtracted from the sample spectra. For spectra of the growing yeast biofilm, the gas correction revealed otherwise hidden variations of relevance for modeling the growth dynamics. As the presented method improved the interpretation of the principle component analysis (PCA) models, it has proven to be a valuable tool for filtering atmospheric variation in ATR-FT-IR spectra.

  6. [Attenuated Total Reflection Infrared Spectroscopy for Degradation Profile of High Density Polyethylene after Weathering Aging].

    PubMed

    Guo, Jun-jun; Yan, Hua; Bao, He-bin; Wang, Xue-mei; Hu, Zhi-de; Yang, Jian-jian

    2015-06-01

    High density polyethylene (HDPE) was widely used as rotational packaging case in the material reserve field. The chemical changes of HDPE, exposed to particular climatic conditions of tropic marine atmosphere for one year-long in Wanning Hainan, were elucidated by the attenuated total reflection infrared spectroscopy (ATR-FTIR). The structural changes were studied qualitatively, mainly from the polymeric chain breaking, branching and oxidation to distinguish the degradation profile. The variations of crystallinity & carbonyl index were also studied quantitatively according to the characteristic peaks intensity & area ratio. Finally, the relationships between structural changes and mechanical properties were investigated. The results showed that the polymeric chain breaking & branching play a leading role before 3 months in the aging progress. Then oxidation phenomena gradually takes place during 3-6 months. The chain branching & oxidation were predominant factors after 6 months. Nine months later, the oxidation was saturated gradually. Furthermore, the aging process is positively correlated to the temperature and irradiation. After 12 months aging, the carbonyl index increased by 112 times and crystallinity was 10% higher than before. The tensile/bending modulus deceased faster than tensile/bending strength of HDPE. The linear degree of tensile modulus and carbonyl index was 0.97. The degree of linearity of tensile strength and crystallinity calculated by feature bands (720-730 cm(-1)) was 0.96. It showed that the mechanical properties of HDPE can be speculated from the structural changes by ATR-FTIR.

  7. Effects of oxidative irrigants on root dentin structure: Attenuated Total Reflection Fourier Transform Infrared Spectroscopy study.

    PubMed

    Atabek, Didem; Bodur, Haluk; Yalçin, Gözde; Kalayci, Şükrü

    2014-09-01

    The aim of this study was to compare the effect of oxidative irrigants on the organic and inorganic structure of root canal dentin. Fifty human 2nd premolar roots were used in the study. The dentin specimens prepared from those teeth were immersed in liquid nitrogen for 15 min. The frozen composition was titrated in a mixer and the obtained dentin powder was kept frozen at -70°C until use. Ten groups of 50mg dentin powder were immersed in agents (A: Ozone for 100 or 200 sec, B: 5.25% NaOCl, C: 2.25% NaOCl, D: 2% Chlorhexidine, E: 0.9% NaCl (control)) for 5 or 10 min. An Attenuated Total Reflection Fourier Transform Infrared Spectrophotometer (ATR FT-IR) was used to analyze dentin powder. The data were statistically analyzed by using Kruskall-Wallis analysis of variance. In all groups, collagen degradation was significantly increased compared to the control and 2% CHX groups (p<0.05). The use of ozone increased collagen degradation significantly compared to the use of 2.25% NaOCl and 2% Chlorhexidine for 5 min (p < 0.05). No significant differences were observed between ozone and 5.25% NaOCl-treated groups (p > 0.05). The structural composition of human dentin was significantly affected by the use of oxidative irrigants at higher concentrations.

  8. Visible attenuated total reflection (ATR): a new technique for high-strength pigment analyses.

    PubMed

    Lee, Kathryn A; Rich, Danny C

    2011-03-01

    A visible-attenuated total reflection (visible-ATR) device was designed to provide a method for directly determining the relative tint strength in high-strength inks. This device showed good reproducibility and the spectra could be correlated to known values of relative tint strength in viscous, highly pigmented inks well within the industry-acceptable error (±5% tint strength). The results of the visible-ATR measurements were compared to those from mid-infrared (mid-IR) and near-infrared (NIR) spectroscopy and the capabilities of those techniques for determining ink strength. Mid-IR analysis was able to directly quantify relative tint strengths, as well as correlating to known values, and to qualify ink products by spectral matching. NIR analysis was able to quantify the tint strength based on the vehicle concentrations in the NIR region. The visible region of the NIR spectrometer was not able to be used for quantification. The vis-ATR and mid-IR spectra showed changes over the time scale of minutes, indicating self-stratification of the pigment and varnish.

  9. Identification of species' blood by attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy.

    PubMed

    Mistek, Ewelina; Lednev, Igor K

    2015-09-01

    Blood is one of the most common and informative forms of biological evidence found at a crime scene. A very crucial step in forensic investigations is identifying a blood stain's origin. The standard methods currently employed for analyzing blood are destructive to the sample and time-consuming. In this study, attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy is used as a confirmatory, nondestructive, and rapid method for distinction between human and animal (nonhuman) blood. Partial least squares-discriminant analysis (PLS-DA) models were built and demonstrated complete separation between human and animal donors, as well as distinction between three separate species: human, cat, and dog. Classification predictions of unknown blood donors were performed by the model, resulting in 100 % accuracy. This study demonstrates ATR FT-IR spectroscopy's great potential for blood stain analysis and species discrimination, both in the lab and at a crime scene since portable ATR FT-IR instrumentation is commercially available.

  10. Development of a time-resolved attenuated total reflectance spectrometer in far-ultraviolet region

    NASA Astrophysics Data System (ADS)

    Morisawa, Yusuke; Higashi, Noboru; Takaba, Kyoko; Kariyama, Naomi; Goto, Takeyoshi; Ikehata, Akifumi; Ozaki, Yukihiro

    2012-07-01

    A far-ultraviolet transient absorption spectrometer based on time-resolved attenuated total reflectance (ATR) has been developed and tested for aqueous solutions of phenol and tryptophan in the region 170-185 nm. In this region, a stable tunable laser was not available, and therefore, white light from a laser-driven Xe lamp source was used. The time resolution, which was determined by the time response of a continuous light detector, was 40 ns. A new ATR cell where a sample liquid is exchanged continuously by a flow system was designed to reduce efficiently the stray light from the excitation light. We have tested the performance of the instrument by using aqueous solutions of phenol and tryptophan, whose photochemistry is already well known. Phenol and tryptophan have very strong absorptions due to a π-π* transition near 180 nm. Even for dilute solutions (10-3 mol dm-3), we could observe decreases in their concentrations due to photochemistry that occurred upon their irradiation with a fourth harmonic generation laser pulse produced by an Nd:YAG laser. The sensitivity of the spectrometer was about 10-4 abs, which corresponded to a concentration variation of 10-3 mol dm-3 for phenol and tryptophan.

  11. Tracing the acetalization of cyclohexanone in CO2-expanded alcohols by attenuated total reflection infrared spectroscopy.

    PubMed

    Seki, Tsunetake; Andanson, Jean-Michel; Jutz, Fabian; Baiker, Alfons

    2009-09-01

    The CO(2)-catalyzed acetalization is regarded as a promising alternative to the conventional acid-catalyzed method from a viewpoint of green chemistry (C. A. Eckert et al., Ind. Eng. Chem. Res. 43, 2605 (2004)). We have applied in situ attenuated total reflection infrared (ATR-IR) spectroscopy for elucidating and monitoring the acetalization of cyclohexanone in CO(2)-expanded ethylene glycol and methanol at 50 degrees C and 3 MPa. The ATR-IR spectra of the reaction mixtures periodically recorded with a ZnSe crystal demonstrate that ATR-IR spectroscopy is a practical tool for tracing the kinetics of acetalizations in situ. In addition, the rate of CO(2) dissolution as well as CO(2) solubility into the cyclohexanone-alcohol mixtures could be evaluated from the CO(2)-nu(3)-antisymmetric stretching band. The ZnSe ATR crystal, however, was corroded during longer use under the acidic conditions realized by the dissolution of CO(2) in the alcohols. In contrast, the corrosion did not occur when a Ge crystal was used instead of a ZnSe crystal, and therefore the application of a Ge ATR crystal is recommended for continuous long-term experiments with these media.

  12. [Discriminant Analysis of Lavender Essential Oil by Attenuated Total Reflectance Infrared Spectroscopy].

    PubMed

    Tang, Jun; Wang, Qing; Tong, Hong; Liao, Xiang; Zhang, Zheng-fang

    2016-03-01

    This work aimed to use attenuated total reflectance Fourier transform infrared spectroscopy to identify the lavender essential oil by establishing a Lavender variety and quality analysis model. So, 96 samples were tested. For all samples, the raw spectra were pretreated as second derivative, and to determine the 1 750-900 cm(-1) wavelengths for pattern recognition analysis on the basis of the variance calculation. The results showed that principal component analysis (PCA) can basically discriminate lavender oil cultivar and the first three principal components mainly represent the ester, alcohol and terpenoid substances. When the orthogonal partial least-squares discriminant analysis (OPLS-DA) model was established, the 68 samples were used for the calibration set. Determination coefficients of OPLS-DA regression curve were 0.959 2, 0.976 4, and 0.958 8 respectively for three varieties of lavender essential oil. Three varieties of essential oil's the root mean square error of prediction (RMSEP) in validation set were 0.142 9, 0.127 3, and 0.124 9, respectively. The discriminant rate of calibration set and the prediction rate of validation set had reached 100%. The model has the very good recognition capability to detect the variety and quality of lavender essential oil. The result indicated that a model which provides a quick, intuitive and feasible method had been built to discriminate lavender oils.

  13. Detection of sibutramine in adulterated dietary supplements using attenuated total reflectance-infrared spectroscopy.

    PubMed

    Deconinck, E; Cauwenbergh, T; Bothy, J L; Custers, D; Courselle, P; De Beer, J O

    2014-11-01

    Sibutramine is one of the most occurring adulterants encountered in dietary supplements with slimming as indication. These adulterated dietary supplements often contain a herbal matrix. When customs intercept these kind of supplements it is almost impossible to discriminate between the legal products and the adulterated ones, due to misleading packaging. Therefore in most cases these products are confiscated and send to laboratories for analysis. This results inherently in the confiscation of legal, non-adulterated products. Therefore there is a need for easy to use equipment and techniques to perform an initial screening of samples. Attenuated total reflectance-infrared (ATR-IR) spectroscopy was evaluated for the detection of sibutramine in adulterated dietary supplements. Data interpretation was performed using different basic chemometric techniques. It was found that the use of ATR-IR combined with the k-Nearest Neighbours (k-NN) was able to detect all adulterated dietary supplements in an external test set and this with a minimum of false positive results. This means that a small amount of legal products will still be confiscated and analyzed in a laboratory to be found negative, but no adulterated samples will pass the initial ATR-IR screening. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Attenuated total reflectance Fourier-transform infrared spectroscopy of carboxylic acids adsorbed onto mineral surfaces

    NASA Astrophysics Data System (ADS)

    Kubicki, J. D.; Schroeter, L. M.; Itoh, M. J.; Nguyen, B. N.; Apitz, S. E.

    1999-09-01

    A suite of naturally-occurring carboxylic acids (acetic, oxalic, citric, benzoic, salicylic and phthalic) and their corresponding sodium salts were adsorbed onto a set of common mineral substrates (quartz, albite, illite, kaolinite and montmorillonite) in batch slurry experiments. Solution pH's of approximately 3 and 6 were used to examine the effects of pH on sorption mechanisms. Attenuated total reflectance Fourier-transform infrared (ATR FTIR) spectroscopy was employed to obtain vibrational frequencies of the organic ligands on the mineral surfaces and in solution. UV/visible spectroscopy on supernatant solutions was also employed to confirm that adsorption from solution had taken place for benzoic, salicylic and phthalic acids. Molecular orbital calculations were used to model possible surface complexes and interpret the experimental spectra. In general, the tectosilicates, quartz and albite feldspar, did not chemisorb (i.e., strong, inner-sphere adsorption) the carboxylate anions in sufficient amounts to produce infrared spectra of the organics after rinsing in distilled water. The clays (illite, kaolinite and montmorillonite) each exhibited similar ATR FTIR spectra. However, the illite sample used in this study reacted to form strong surface and aqueous complexes with salicylic acid before being treated to remove free Fe-hydroxides. Chemisorption of carboxylic acids onto clays is shown to be limited without the presence of Fe-hydroxides within the clay matrix.

  15. Metallic attenuated total reflection infrared hollow fibers for robust optical transmission systems

    NASA Astrophysics Data System (ADS)

    Jing, Chengbin; Guo, Hong; Hu, Zhigao; Yang, Pingxiong; Chu, Junhao; Liu, Aiyun; Shi, Yiwei

    2014-07-01

    A durable metallic attenuated total reflection (ATR) hollow fiber (bore size: 1.45 mm, wall thickness: 50 μm) was designed and fabricated based on a nickel capillary tube and hexagonal germanium dioxide (GeO2). The anomalous dispersion of the hexagonal GeO2 layer grown inside a nickel tube achieves low-loss light transmission at two peak-power wavelengths for CO2 laser devices (10.2 and 10.6 μm). An 11-28 W, 10.2 or 10.6 μm CO2 laser power was steadily delivered via a fiber elastically bent from 0° to 90° (radius: 45 cm) for over 40 min (transmission loss: 0.22 to 4.2 dB/m). Theoretically fitting the measured temperatures showed that front-end clipping caused greater thermal loading than the distributed mode absorption. The maximum external temperature of a nickel ATR fiber is much lower than that of a silica glass ATR fiber owing to their different heat dissipation abilities. The HE11 mode purity of the output beam profiles decreased from 90.3% to 44.7% as the bending angle increased from 0° to 90°. Large core sizes and wall roughnesses (scattering loss 0.04 dB/m) contributed to mode mixing and excess losses that were above the value predicted by the classical Marcatili and Schmeltzer equation (0.024-0.037 dB/m).

  16. Attenuated total reflectance fourier transform infrared analysis of fly ash geopolymer gel aging.

    PubMed

    Rees, Catherine A; Provis, John L; Lukey, Grant C; van Deventer, Jannie S J

    2007-07-17

    Structural changes in fly ash geopolymers activated with different sodium hydroxide and silicate concentrations are investigated using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy over a period of 200 days. A strong correlation is found between the concentration of silicate monomer in the activating solution and the position of the main Si-O-T stretching band in the FTIR spectrum, which gives an indication of the relative changes in the gel Si/Al ratio. The FTIR spectra of geopolymer samples with activating solution concentrations of up to 1.2 M SiO2 indicate that an Al-rich gel forms before the final gel composition is reached. The time required for the system to reach a steady gel composition depends on the silicate activating solution concentration and speciation. Geopolymers activated with solutions containing predominantly high-order silicate species rapidly reach a steady gel composition without first forming an Al-rich gel. A minimum silicate monomer concentration of approximately 0.6 M is required to shift the geopolymer synthesis mechanism from hydroxide activation to silicate activation. Silicate speciation in the activating solutions also affects zeolite formation and geopolymer microstructures, with a more homogeneous microstructure and less zeolite formation observed at a higher SiO2 content.

  17. Brain tumour differentiation: rapid stratified serum diagnostics via attenuated total reflection Fourier-transform infrared spectroscopy.

    PubMed

    Hands, James R; Clemens, Graeme; Stables, Ryan; Ashton, Katherine; Brodbelt, Andrew; Davis, Charles; Dawson, Timothy P; Jenkinson, Michael D; Lea, Robert W; Walker, Carol; Baker, Matthew J

    2016-05-01

    The ability to diagnose cancer rapidly with high sensitivity and specificity is essential to exploit advances in new treatments to lead significant reductions in mortality and morbidity. Current cancer diagnostic tests observing tissue architecture and specific protein expression for specific cancers suffer from inter-observer variability, poor detection rates and occur when the patient is symptomatic. A new method for the detection of cancer using 1 μl of human serum, attenuated total reflection-Fourier transform infrared spectroscopy and pattern recognition algorithms is reported using a 433 patient dataset (3897 spectra). To the best of our knowledge, we present the largest study on serum mid-infrared spectroscopy for cancer research. We achieve optimum sensitivities and specificities using a Radial Basis Function Support Vector Machine of between 80.0 and 100 % for all strata and identify the major spectral features, hence biochemical components, responsible for the discrimination within each stratum. We assess feature fed-SVM analysis for our cancer versus non-cancer model and achieve 91.5 and 83.0 % sensitivity and specificity respectively. We demonstrate the use of infrared light to provide a spectral signature from human serum to detect, for the first time, cancer versus non-cancer, metastatic cancer versus organ confined, brain cancer severity and the organ of origin of metastatic disease from the same sample enabling stratified diagnostics depending upon the clinical question asked.

  18. Rapid profiling of Swiss cheese by attenuated total reflectance (ATR) infrared spectroscopy and descriptive sensory analysis.

    PubMed

    Kocaoglu-Vurma, N A; Eliardi, A; Drake, M A; Rodriguez-Saona, L E; Harper, W J

    2009-08-01

    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.

  19. Development of an ultra-compact mid-infrared attenuated total reflectance spectrophotometer

    NASA Astrophysics Data System (ADS)

    Kim, Dong Soo; Lee, Tae-Ro; Yoon, Gilwon

    2014-07-01

    Mid-infrared spectroscopy has been an important tool widely used for qualitative analysis in various fields. However, portable or personal use is size and cost prohibitive for either Fourier transform infrared or attenuated total reflectance (ATR) spectrophotometers. In this study, we developed an ultra-compact ATR spectrophotometer whose frequency band was 5.5-11.0 μm. We used miniature components, such as a light source fabricated by semiconductor technology, a linear variable filter, and a pyro-electric array detector. There were no moving parts. Optimal design based on two light sources, a zippered configuration of the array detector and ATR optics could produce absorption spectra that might be used for qualitative analysis. A microprocessor synchronized the pulsed light sources and detector, and all the signals were processed digitally. The size was 13.5×8.5×3.5 cm3 and the weight was 300 grams. Due to its low cost, our spectrophotometer can replace many online monitoring devices. Another application could be for a u-healthcare system installed in the bathroom or attached to a smartphone for monitoring substances in body fluids.

  20. Quantifying amyloid fibrils in protein mixtures via infrared attenuated-total-reflection spectroscopy.

    PubMed

    Wang, Pei; Bohr, Wilhelm; Otto, Markus; Danzer, Karin M; Mizaikoff, Boris

    2015-05-01

    Amyloid aggregation of proteins is usually associated with amyloid diseases. A distinct feature of protein aggregation is the increase of crossed β-sheet structures. Infrared attenuated-total-reflectance (IR-ATR) spectroscopy is a sensitive optical technique that has the potential to provide secondary structure characteristics of proteins even in complex biological samples. In this study we report the analysis of secondary structures of proteins, using the amide I band for the detection and quantification of amyloid fibrils in protein mixtures by use of IR-ATR techniques, at comparatively low sample concentrations. From the experimental results, an analytical model of the relationship between the IR spectra of protein mixtures and the individual mixture components was established using spectral-deconvolution procedures and curve-fitting methods. On the basis of this model, four ratios were shown to provide direct information on amyloid aggregated fibrils via the increase of crossed β-sheet structures in protein-mixture samples. In conclusion, this study confirms the utility of IR spectroscopy for analyzing protein mixtures and for identifying amyloid fibril information within such complex multi-component samples.

  1. [Characterization of oxidation on pyrite by in situ attenuated total reflection-Fourier transform infrared spectroscopy].

    PubMed

    Zhang, Ping; Chen, Yong-Heng; Liu, Juan; Wang, Chun-Lin

    2008-11-01

    Pyrite is one of common natural minerals in the environment, which is easily oxidated and is the main source of acidity mine drainage (AMD). The study on the oxidation of pyrite is helpful to comprehend the mechanism of its pollution. In the present paper, the oxidation of pyrite under the condition of air and water was respectively investigated by the attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) through the designing experiment on the formation of carbon dioxide by the reaction of carbonate in pyrite with sulfuric acid formed by the oxidation of pyrite. The CO2 measurement by in situ ATR indicated that the oxidation rate of pyrite both in the air and in water both reduced by time and the latter reduced more obviously than the former, which indicates that the oxidation rate of pyrite in water is slower than that in the air. In the ATR measurement, the double absorption peaks at 2 350 cm(-1) that indicates CO2 have high selectivity, and permits the in situ analysis.

  2. Screening the origin and weathering of oil slicks by attenuated total reflectance mid-IR spectrometry.

    PubMed

    Fernández-Varela, R; Suárez-Rodríguez, D; Gómez-Carracedo, M P; Andrade, J M; Fernández, E; Muniategui, S; Prada, D

    2005-11-15

    The combination of attenuated total reflectance-fourier transform mid-infrared spectrometry (ATR-FTMIR) and multivariate pattern recognition is presented as a fast and convenient methodology to ascertain the source product an oil slick comes from and to evaluate the extent of its weathering. Different types of hydrocarbons (including crude oils, several heavy distillates and the Prestige's heavy fuel oil) were spilled on metallic containers designed ad hoc and their fate monitored by ATR-FTMIR. Not only environmental conditions were considered for weathering but artificial IR- and UV-irradiation. Pattern-recognition studies revealed that the different hydrocarbons clustered at different locations on the score plots and that the samples corresponding to each oil became ordered according to the extent of their weathering. Among them, fuel oil samples coming from the recent disaster of the Prestige tanker off the Galician shoreline showed a distinctive behaviour. Comparison of natural-, IR- and UV-weathering of a crude oil showed that IR solar radiation can be important in oil-weathering, in addition to broadly-reported UV degradation.

  3. Quantitative determination of band distortions in diamond attenuated total reflectance infrared spectra.

    PubMed

    Boulet-Audet, Maxime; Buffeteau, Thierry; Boudreault, Simon; Daugey, Nicolas; Pézolet, Michel

    2010-06-24

    Due to its unmatched hardness and chemical inertia, diamond offers many advantages over other materials for extreme conditions and routine analysis by attenuated total reflection (ATR) infrared spectroscopy. Its low refractive index can offer up to a 6-fold absorbance increase compared to germanium. Unfortunately, it also results for strong bands in spectral distortions compared to transmission experiments. The aim of this paper is to present a methodological approach to determine quantitatively the degree of the spectral distortions in ATR spectra. This approach requires the determination of the optical constants (refractive index and extinction coefficient) of the investigated sample. As a typical example, the optical constants of the fibroin protein of the silk worm Bombyx mori have been determined from the polarized ATR spectra obtained using both diamond and germanium internal reflection elements. The positions found for the amide I band by germanium and diamond ATR are respectively 6 and 17 cm(-1) lower than the true value dtermined from the k(nu) spectrum, which is calculated to be 1659 cm(-1). To determine quantitatively the effect of relevant parameters such as the film thickness and the protein concentration, various spectral simulations have also been performed. The use of a thinner film probed by light polarized in the plane of incidence and diluting the protein sample can help in obtaining ATR spectra that are closer to their transmittance counterparts. To extend this study to any system, the ATR distortion amplitude has been evaluated using spectral simulations performed for bands of various intensities and widths. From these simulations, a simple empirical relationship has been found to estimate the band shift from the experimental band height and width that could be of practical use for ATR users. This paper shows that the determination of optical constants provides an efficient way to recover the true spectrum shape and band frequencies of

  4. Compositional features of cotton plant biomass fractions characterized by attenuated total reflection Fourier transform infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Cotton is one of the most important and widely grown crops in the world. In addition to natural textile fiber production as a primary purpose, it yields a high grade vegetable oil for human consumption and also carbohydrate fiber and protein byproducts for animal feed. In this work, attenuated total...

  5. Excitation of plasmonic terahertz photovoltaic effects in a periodic two-dimensional electron system by the attenuated total reflection method

    SciTech Connect

    Fateev, D. V. Mashinsky, K. V.; Bagaeva, T. Yu.; Popov, V. V.

    2015-01-15

    The problem of the rectification of terahertz radiation due to plasmonic nonlinearities in a periodic two-dimensional electron system upon the excitation of plasma oscillations by the attenuated total reflection method is solved. This model allows the independent study of different plasmonic rectification mechanisms, i.e., plasmonic electron drag and plasmonic ratchet effects.

  6. Secondary cell wall development in cotton fibers as examined with attenuated total reflection Fourier transform infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. The selected harvesting points coincide with secondary cell wall (SCW) development in the fibers. Progressive but moderat...

  7. Characterization of southern yellow pine bark layers by Attenuated Total Reflectance (ATR) and Fourier Transform Infrared (FT-IR) Spectroscopy

    Treesearch

    Thomas L. Eberhardt

    2009-01-01

    The outer bark (rhytidome) of the southern yellow pines is a complex structure comprised of alternating layers of obliterated phloem and periderm tissues, with the latter comprised of three layers, those being phellem, phellogen, and phelloderm. An attenuated total reflectance (ATR) sampling accessory, coupled with a Fourier transform infrared (FTIR) spectrometer,...

  8. Metallic attenuated total reflection infrared hollow fibers for robust optical transmission systems

    SciTech Connect

    Jing, Chengbin; Guo, Hong; Hu, Zhigao; Yang, Pingxiong; Chu, Junhao; Liu, Aiyun; Shi, Yiwei

    2014-07-07

    A durable metallic attenuated total reflection (ATR) hollow fiber (bore size: 1.45 mm, wall thickness: 50 μm) was designed and fabricated based on a nickel capillary tube and hexagonal germanium dioxide (GeO{sub 2}). The anomalous dispersion of the hexagonal GeO{sub 2} layer grown inside a nickel tube achieves low-loss light transmission at two peak-power wavelengths for CO{sub 2} laser devices (10.2 and 10.6 μm). An 11–28 W, 10.2 or 10.6 μm CO{sub 2} laser power was steadily delivered via a fiber elastically bent from 0° to 90° (radius: 45 cm) for over 40 min (transmission loss: 0.22 to 4.2 dB/m). Theoretically fitting the measured temperatures showed that front-end clipping caused greater thermal loading than the distributed mode absorption. The maximum external temperature of a nickel ATR fiber is much lower than that of a silica glass ATR fiber owing to their different heat dissipation abilities. The HE{sub 11} mode purity of the output beam profiles decreased from 90.3% to 44.7% as the bending angle increased from 0° to 90°. Large core sizes and wall roughnesses (scattering loss 0.04 dB/m) contributed to mode mixing and excess losses that were above the value predicted by the classical Marcatili and Schmeltzer equation (0.024–0.037 dB/m).

  9. Discerning some Tylenol brands using attenuated total reflection Fourier transform infrared data and multivariate analysis techniques.

    PubMed

    Msimanga, Huggins Z; Ollis, Robert J

    2010-06-01

    Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to classify acetaminophen-containing medicines using their attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectra. Four formulations of Tylenol (Arthritis Pain Relief, Extra Strength Pain Relief, 8 Hour Pain Relief, and Extra Strength Pain Relief Rapid Release) along with 98% pure acetaminophen were selected for this study because of the similarity of their spectral features, with correlation coefficients ranging from 0.9857 to 0.9988. Before acquiring spectra for the predictor matrix, the effects on spectral precision with respect to sample particle size (determined by sieve size opening), force gauge of the ATR accessory, sample reloading, and between-tablet variation were examined. Spectra were baseline corrected and normalized to unity before multivariate analysis. Analysis of variance (ANOVA) was used to study spectral precision. The large particles (35 mesh) showed large variance between spectra, while fine particles (120 mesh) indicated good spectral precision based on the F-test. Force gauge setting did not significantly affect precision. Sample reloading using the fine particle size and a constant force gauge setting of 50 units also did not compromise precision. Based on these observations, data acquisition for the predictor matrix was carried out with the fine particles (sieve size opening of 120 mesh) at a constant force gauge setting of 50 units. After removing outliers, PCA successfully classified the five samples in the first and second components, accounting for 45.0% and 24.5% of the variances, respectively. The four-component PLS-DA model (R(2)=0.925 and Q(2)=0.906) gave good test spectra predictions with an overall average of 0.961 +/- 7.1% RSD versus the expected 1.0 prediction for the 20 test spectra used.

  10. Tethered bilayer lipid membranes studied by simultaneous attenuated total reflectance infrared spectroscopy and electrochemical impedance spectroscopy

    PubMed Central

    Erbe, Andreas; Bushby, Richard J.; Evans, Stephen D.; Jeuken, Lars J. C.

    2013-01-01

    The formation of tethered lipid bilayer membranes (tBLMs) from unilamelar vesicles of egg yolk phosphatidylcholine (EggPC) on mixed self–assembled monolayers (SAMs) from varying ratios of 6-mercaptohexanol and EO3Cholesteryl on gold has been monitored by simultaneous attenuated total reflectance fourier transform infrared (ATR–FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The influence of the lipid orientation (and hence the anisotropy) of lipids on a gold film on the dichroic ratio was studied by simulations of spectra with a matrix method for anisotropic layers. It is shown that for certain tilt angles of the dielectric tensor of the adsorbed anisotropic layer dispersive and negative absorption bands are possible. The experimental data indicates that the structure of the assemblies obtained varies with varying SAM composition. On SAMs with a high content of EO3Cholesteryl, tBLMs with reduced fluidity are formed. For SAMs with high content of 6-mercaptohexanol, the results are consistent with the adsorption of flattened vesicles, while spherical vesicles have been found in a small range of surface compositions. The kinetics of the adsorption process is consistent with the assumption of spherical vesicles as long–living intermediates for surfaces of high 6-mercaptohexanol content. No long–living spherical vesicles have been detected for surfaces with large fraction of EO3Cholesteryl tethers. The observed differences between the surfaces suggest that for the formation of tBLMs (unlike supported BLMs) no critical surface coverage of vesicles is needed prior to lipid bilayer formation. PMID:17388505

  11. Evaluation of various polyethylene as potential dosimeters by attenuated total reflectance-Fourier-transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Halperin, Fred; Collins, Greta; DiCicco, Michael; Logar, John

    2014-12-01

    Various types of polyethylene (PE) have been evaluated in the past for use as a potential dosimeter, chiefly via the formation of an unsaturated transvinylene (TV) double-bond resulting from exposure to ionizing radiation. The utilization of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy in characterizing TV formation in irradiated PE for a potential dosimeter has yet to be fully developed. In this initial investigation, various PE films/sheets were exposed to ionizing radiation in a high-energy 5 megaelectron volt (MeV) electron beam accelerator in the 10-500 kilogray (kGy) dose range, followed by ATR-FTIR analysis of TV peak formation at the 965 cm-1 wavenumber. There was an upward trend in TV formation for low-density polyethylene (LDPE) films and high-density polyethylene (HDPE) sheets as a function of absorbed dose in the 10-50 kGy dose range, however, the TV response could not be equated to a specific absorbed dose. LDPE film displayed a downward trend from 50 kGy to 250 kGy and then scattering up to 500 kGy; HDPE sheets demonstrated an upward trend in TV formation up to 500 kGy. For ultra-high molecular weight polyethylene (UHMWPE) sheets irradiated up to 150 kGy, TV response was equivalent to non-irradiated UHMWPE, and a minimal upward trend was observed for 200 kGy to 500 kGy. The scatter of the data for the irradiated PE films/sheets is such that the TV response could not be equated to a specific absorbed dose. A better correlation of the post-irradiation TV response to absorbed dose may be attained through a better understanding of variables.

  12. [Attenuated total reflection-fourier transform infrared spectroscopic study of dried shark fin products].

    PubMed

    Han, Wan-qing; Luo, Hai-ying; Xian, Yan-ping; Luo, Dong-hui; Mu, Torng-na; Guo, Xin-dong

    2015-02-01

    Sixty-four pieces of shark fin dried products (including real, fake and artificial shark fin products) and real products coated with gelatin were rapidly and nondestructively analyzed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The characteristic of IR spectrograms among the above four kinds of samples were systematically studied and comparied, the results showed that the spectrograms of the same kind of samples were repeatable, and different kinds of shark fin products presented significant differences in the spectrograms, which mainly manifested as the specific absorption peaks of amido bonds in protein (1650, 1544 cm(-1)) and skeletal vibration in polysaccharide (1050 cm(-1)). The spectrograms of real shark fins were characterized by the strong absorption peaks of protein characteristic amide I and II absorbent (1650, 1544 cm(-1)) and relatively weak C--O--C vibration absorbent (1050 cm(-1)) owing to the high content of protein and relatively low level of polysaccharide. For fake shark fin products that were molded form by mixing together with the offcut of shark, collagen and other substances, the introduction of non-protein materials leaded to the weaker amido bonds absorbent than real products along with a 30 cm(-1) blue shift of amide I absorbent. Opposite to the real sample, the relatively strong absorption peak of polysaccharide (approximately 1047 cm(-1)) and barely existed amide absorbent were the key features of the spectrogram of artificial samples, which was synthersized by polysaccharide like sodium alginate. Real samples coated with gelatin, the peak strength of protein and polysaccharide were decreased simultaneously when the data collection was taken at the surface of sample, while the spectrogram presented no significant difference to real samples when the data was collected in the section. The results above indicated that by analyzing the characteristic of IR spectrograms and the value range of Apro

  13. Infrared attenuated total reflection (IR-ATR) spectroscopy for detecting drugs in human saliva.

    PubMed

    Hans, Kerstin M-C; Müller, Susanne; Sigrist, Markus W

    2012-06-01

    The consumption of drugs is of great concern worldwide. Various drug tests for humans have been developed but there is no compact and easy-to-use test device available yet for direct semi-quantitative drug testing in the field. We suggest using attenuated total reflection (ATR) infrared spectroscopy as a sensing method to analyze human saliva samples with respect to drugs. In this paper, we present ATR spectra in the infrared range between 2300 and 900 cm(-1) as a first step towards such a device. We emphasize the common drug cocaine and its metabolites and investigate the problems of spectral interferences of selected diluents, masking agents, common medication, and soft drinks. Furthermore, spectra of saliva samples are recorded and a time-dependent change of the spectral signatures after alcohol consumption is presented. To the best of our knowledge, it is the first time that not only spectra of the drug of interest (cocaine) dissolved in water and in saliva but also spectra of interfering compounds possibly present in the saliva sample of a tested subject are discussed. This paper presents the most appropriate spectral range for strong cocaine absorption (including its metabolites) and minimum interference by the investigated substances. This spectral window is found to be between 1800 and 1710 cm(-1). In addition, we demonstrate the feasibility to identify cocaine in saliva at a concentration of 0.020 mg/ml with IR-ATR-spectroscopy without any separation or extraction procedures. For example, this technique could also be applied for drug detection in waste water. Copyright © 2011 John Wiley & Sons, Ltd.

  14. Attenuated total reflection micro FTIR characterisation of pigment-binder interaction in reconstructed paint films.

    PubMed

    Mazzeo, R; Prati, S; Quaranta, M; Joseph, E; Kendix, E; Galeotti, M

    2008-09-01

    The interaction of pigments and binding media may result in the production of metal soaps on the surface of paintings which modifies their visible appearance and state of conservation. To characterise more fully the metal soaps found on paintings, several historically accurate oil and egg yolk tempera paint reconstructions made with different pigments and naturally aged for 10 years were submitted to attenuated total reflectance Fourier transform infrared (ATR FTIR) microspectroscopic analyses. Standard metal palmitates were synthesised and their ATR spectra recorded in order to help the identification of metal soaps. Among the different lead-based pigments, red lead and litharge seemed to produce a larger amount of carboxylates compared with lead white, Naples yellow and lead tin yellow paints. Oil and egg tempera litharge and red lead paints appeared to be degraded into lead carbonate, a phenomenon which has been observed for the first time. The formation of metal soaps was confirmed on both oil and egg tempera paints based on zinc, manganese and copper and in particular on azurite paints. ATR mapping analyses showed how the areas where copper carboxylates were present coincided with those in which azurite was converted into malachite. Furthermore, the key role played by manganese in the production of metals soaps on burnt and raw sienna and burnt and raw umber paints has been observed for the first time. The formation of copper, lead, manganese, cadmium and zinc metal soaps was also identified on egg tempera paint reconstructions even though, in this case, the overlapping of the spectral region of the amide II band with that of metal carboxylates made their identification difficult.

  15. Quantification of bovine immunoglobulin G using transmission and attenuated total reflectance infrared spectroscopy.

    PubMed

    Elsohaby, Ibrahim; McClure, J Trenton; Riley, Christopher B; Shaw, R Anthony; Keefe, Gregory P

    2016-01-01

    In this study, we evaluated and compared the performance of transmission and attenuated total reflectance (ATR) infrared (IR) spectroscopic methods (in combination with quantification algorithms previously developed using partial least squares regression) for the rapid measurement of bovine serum immunoglobulin G (IgG) concentration, and detection of failure of transfer of passive immunity (FTPI) in dairy calves. Serum samples (n = 200) were collected from Holstein calves 1-11 days of age. Serum IgG concentrations were measured by the reference method of radial immunodiffusion (RID) assay, transmission IR (TIR) and ATR-IR spectroscopy-based assays. The mean IgG concentration measured by RID was 17.22 g/L (SD ±9.60). The mean IgG concentrations predicted by TIR and ATR-IR spectroscopy methods were 15.60 g/L (SD ±8.15) and 15.94 g/L (SD ±8.66), respectively. RID IgG concentrations were positively correlated with IgG levels predicted by TIR (r = 0.94) and ATR-IR (r = 0.92). The correlation between 2 IR spectroscopic methods was 0.94. Using an IgG concentration <10 g/L as the cut-point for FTPI cases, the overall agreement between TIR and ATR-IR methods was 94%, with a corresponding kappa value of 0.84. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for identifying FTPI by TIR were 0.87, 0.97, 0.91, 0.95, and 0.94, respectively. Corresponding values for ATR-IR were 0.87, 0.95, 0.86, 0.95, and 0.93, respectively. Both TIR and ATR-IR spectroscopic approaches can be used for rapid quantification of IgG level in neonatal bovine serum and for diagnosis of FTPI in dairy calves.

  16. Hygrothermal degradation of 3-glycidoxypropyltrimethoxysilane films studied by neutron and X-ray reflectivity and attenuated total reflection infrared spectroscopy.

    SciTech Connect

    Tallant, David Robert; Garcia, Manuel Joseph; Majewski, Jaroslaw; Kent, Michael Stuart; Yim, Hyun

    2005-05-01

    Thin films of organosilanes have great technological importance in the areas of adhesion promotion, durability, and corrosion resistance. However, it is well-known that water can degrade organosilane films, particularly at elevated temperatures. In this work, X-ray and neutron reflectivity (XR and NR) were combined with attenuated total reflection infrared (ATR-IR) spectroscopy to study the chemical and structural changes within thin films of (3-glycidoxypropyl)trimethoxysilane (GPS) after exposure for various periods of time to air saturated with either D{sub 2}O or H{sub 2}O at 80 C. For NR and XR, ultrathin ({approx}100 {angstrom}) films were prepared by spin-coating. Both D{sub 2}O and H{sub 2}O provide neutron scattering contrast with GPS. Variations in the neutron scattering length density (SLD) profiles (a function of mass density and atomic composition) with conditioning time were measured after drying the samples out and also swelled with H{sub 2}O or D{sub 2}O vapor at room temperature. For samples that were dried out prior to measurement, little or no change was observed for H{sub 2}O conditioning up to 3.5 days, but large changes were observed after 30 days of conditioning. The range of conditioning time for this structural change was narrowed to between 4 and 10 days with XR. The SLD profiles indicated that the top portion of the GPS film was transformed into a thick low-density layer after conditioning, but the bottom portion showed little structural change. A previous NR study of as-prepared GPS films involving swelling with deuterated nitrobenzene showed that the central portion of the film has much lower cross-link density than the region nearest the substrate. The present data show that the central portion also swells to a much greater extent with water and hydrolyzes more rapidly. The chemical degradation mechanism was identified by IR as hydrolysis of siloxane bonds. For ATR-IR, GPS films were prepared by dip-coating, which resulted in a greater

  17. Attenuated Total Reflection Surface-Enhanced Infrared Absorption (ATR SEIRA) Spectroscopy for the Analysis of Fatty Acids on Silver Nanoparticles.

    PubMed

    Kato, Yuichi; Kikugawa, Masashi; Sudo, Eiichi

    2017-09-01

    The application of attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR SEIRA) to the analysis of fatty acids on silver nanoparticles was investigated. Attenuated total reflection measurements using four types of internal reflection elements (IREs)-zinc selenide, diamond, silicon, and germanium-were performed for silver nanoparticles modified with fatty acids, and germanium IRE was shown to be suitable for the analysis of silver nanoparticles, even when the sample had a high refractive index. Fatty acids coating the silver nanoparticles could be directly identified by SEIRA enhancement, because both symmetric carboxylate stretching vibration and methylene wagging vibration were strongly detected. Furthermore, the peak positions for methylene wagging vibration differed depending on the carbon number of the fatty acid, so that information from the ATR SEIRA spectra makes it possible to identify substances coating silver nanoparticles. Therefore, ATR SEIRA would appear to have significant potential as a technique for the identification of substances coated on metal nanoparticle surfaces.

  18. Effects of Particle Size on the Attenuated Total Reflection Spectrum of Minerals.

    PubMed

    Udvardi, Beatrix; Kovács, István J; Fancsik, Tamás; Kónya, Péter; Bátori, Miklósné; Stercel, Ferenc; Falus, György; Szalai, Zoltán

    2016-09-26

    This study focuses on particle size effect on monomineralic powders recorded using attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy. Six particle size fractions of quartz, feldspar, calcite, and dolomite were prepared (<2, 2-4, 4-8, 8-16, 16-32, and 32-63 µm). It is found that the width, intensity, and area of bands in the ATR FT-IR spectra of minerals have explicit dependence on the particle size. As particle size increases, the intensity and area of IR bands usually decrease while the width of bands increases. The band positions usually shifted to higher wavenumbers with decreasing particle size. Infrared spectra of minerals are the most intensive in the particle size fraction of 2-4 µm. However, if the particle size is very small (<2 µm), due to the wavelength and penetration depth of the IR light, intensity decreases. Therefore, the quantity of very fine-grained minerals may be underestimated compared to the coarser phases. A nonlinear regression analysis of the data indicated that the average coefficients and indices of the power trend line equation imply a very simplistic relationship between median particle diameter and absorbance at a given wavenumber. It is concluded that when powder samples with substantially different particle size are compared, as in regression analysis for modal predictions using ATR FT-IR, it is also important to report the grain size distribution or surface area of samples. The band area of water (3000-3620 cm(-1)) is similar in each mineral fraction, except for the particles below 2 µm. It indicates that the finest particles could have disproportionately more water adsorbed on their larger surface area. Thus, these higher wavenumbers of the ATR FT-IR spectra may be more sensitive to this spectral interference if the number of particles below 2 µm is considerable. It is also concluded that at least a proportion of the moisture could be very adhesive to the particles due to the band

  19. Comparative study of Fourier transform infrared spectroscopy in transmission, attenuated total reflection, and total reflection modes for the analysis of plastics in the cultural heritage field.

    PubMed

    Picollo, Marcello; Bartolozzi, Giovanni; Cucci, Costanza; Galeotti, Monica; Marchiafava, Veronica; Pizzo, Benedetto

    2014-01-01

    This study was completed within the framework of two research projects dealing with the conservation of contemporary artworks. The first is the Seventh Framework Project (FP7) of the European Union, Preservation of Plastic ARTefacts in Museum Collections (POPART), spanning years 2008-2012, and the second is the Italian project funded by the Tuscan Region, Preventive Conservation of Contemporary Art (Conservazione Preventiva dell'Arte Contemporanea (COPAC)), spanning 2011-2013. Both of these programs pointed out the great importance of having noninvasive and portable analytical techniques that can be used to investigate and characterize modern and contemporary artworks, especially those consisting of synthetic polymers. Indeed, despite the extensive presence of plastics in museum collections, there is still a lack of analytical tools for identifying, characterizing, and setting up adequate conservation strategies for these materials. In this work, the potentials of in situ and noninvasive Fourier transform infrared (FT-IR) spectroscopy, implemented by means of portable devices that operate in reflection mode, are investigated with a view to applying the results in large-scale surveys of plastic objects in museums. To this end, an essential prerequisite are the reliability of spectral data acquired in situ and the availability of spectral databases acquired from reference materials. A collection of polymeric samples, which are available commercially as ResinKit, was analyzed to create a reference spectral archive. All the spectra were recorded using three FT-IR configurations: transmission (trans), attenuated total reflection (ATR), and total reflection (TR). A comparative evaluation of the data acquired using the three instrumental configurations is presented, together with an evaluation of the similarity percentages and a discussion of the critical cases.

  20. A modified golden gate attenuated total reflection (ATR) cell for monitoring phase transitions in multicomponent fluids at high temperatures.

    PubMed

    Novitskiy, Alexander A; Ke, Jie; Comak, Gurbuz; Poliakoff, Martyn; George, Michael W

    2011-08-01

    A new continuous flow method using attenuated total reflection infrared (ATR-IR) spectroscopy has been developed for monitoring phase transitions in multicomponent fluids at high pressures and temperatures. Our approach uses Fourier transform infrared (FT-IR) and a modified Golden Gate attenuated total reflection (ATR) cell and exploits the fact that the absorbance of a vapor is much lower than that of the corresponding liquid to monitor the phase transition between vapor and liquid. We demonstrate that this method can provide quantitative measurements on both the dew point and the bubble point. We have validated our approach using three single-component systems (EtOH, MeOH, and H(2)O) and a binary system of EtOH + H(2)O, monitoring phase transitions at temperature up to 300 °C and pressure up to 10 MPa.

  1. A preliminary evaluation of attenuated total reflection Fourier transform infrared spectroscopy for the hematological analysis of thalassemias.

    PubMed

    Wan, Jun-Hui; Tian, Pei-Ling; Yin, Hao; Han, Yun; Wei, Xiang-Cai; Pan, Tao

    2013-01-01

    The effectiveness of attenuated total reflection Fourier transform infrared spectroscopy for the hematological analysis of thalassemias was evaluated. The correlations of hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin between routine method and attenuated total reflection Fourier transform infrared spectroscopy were analyzed using linear regression analysis. Appropriate cut-off values of predicted mean corpuscular volume and predicted mean corpuscular hemoglobin in screening of thalassemias were derived from the receiver operator characteristic curve conducted on 103 subjects. Obvious positive correlations of hemoglobin (beta=0.876, R(2)=0.791, P<0.001), mean corpuscular volume (beta=0.656, R(2)=0.516, P<0.001) and mean corpuscular hemoglobin (beta=0.674, R(2)=0.583, P<0.001) were observed between routine method and attenuated total reflection Fourier transform infrared spectroscopy. Based on the receiver operator characteristic curve analysis, the best cut off value of predicted mean corpuscular volume for the phenotype-positive subjects was found to be 79.9 fl with a sensitivity of 100.0% and a specificity of 97.8%, and the proposed cut off value of predicted mean corpuscular hemoglobin was 27.3 pg with a sensitivity of 100.0% and a specificity of 96.8%. The area under curve was 0.996 for predicted mean corpuscular volume and 0.992 for predicted mean corpuscular hemoglobin, respectively. The established method could be an additional potentially promising tool for the preliminary screening of thalassemias in population prevention and control program. The main advantage of this method is no unwanted chemical regents compared with conventional method. Strategy for the development of this method could be of use for the other important parameters of thalassemias. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  2. A method to overcome the diffraction limit in infrared microscopy using standing waves in an attenuated total reflection configuration

    NASA Astrophysics Data System (ADS)

    Hendaoui, Nordine; Mani, Aladin; Liu, Ning; Tofail, Syed M.; Silien, Christophe; Peremans, André

    2017-01-01

    A method is proposed to overcome the diffraction limit of spatial resolution in infrared microscopy. To achieve this, standing waves in an attenuated total reflection configuration were generated to spatially modulate the absorbance of adsorbate vibrational transitions. A numerical simulation was undertaken. It showed that chemical imaging with a spatial resolution of approximately 100 nm is achievable in the case of self-assembled patterns (ofoctdecyltrichlorosilane [CH3-(CH2)17-SiCl3]), when probing the methyl modes located near 3.5 micrometres.

  3. Use of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy To Identify Microbial Metabolic Products on Carbonate Mineral Surfaces▿ †

    PubMed Central

    Bullen, Heather A.; Oehrle, Stuart A.; Bennett, Ariel F.; Taylor, Nicholas M.; Barton, Hazel A.

    2008-01-01

    This paper demonstrates the use of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to detect microbial metabolic products on carbonate mineral surfaces. By creating an ATR-FTIR spectral database for specific organic acids using ATR-FTIR spectroscopy we were able to distinguish metabolic acids on calcite surfaces following Escherichia coli growth. The production of these acids by E. coli was verified using high-performance liquid chromatography with refractive index detection. The development of this technique has allowed us to identify microbial metabolic products on carbonate surfaces in nutrient-limited cave environments. PMID:18502924

  4. High-throughput evaluation of olefin copolymer composition by means of attenuated total reflection Fourier tranform infrared spectroscopy.

    PubMed

    Tuchbreiter, A; Marquardt, J; Zimmermann, J; Walter, P; Mülhaupt, R; Kappler, B; Faller, D; Roths, T; Honerkamp, J

    2001-01-01

    As a consequence of developing fully automated reactors for organic and organometallic synthesis and polymerizations combined with rapid on-line analysis, databases, and data mining, the analysis of polymers with respect to composition and properties has been speeded up. High-throughput evaluation of olefin copolymers requires fast measurements and high accuracy without tedious sample preparation such as pressing KBr pellets. This has been achieved by using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR spectroscopy) in conjunction with multivariate calibration in order to determine the composition of olefin copolymers such as ethene/propene, ethene/1-hexene and ethene/1-octene copolymers.

  5. Obtaining spectrally selective images of objects in attenuated total reflection regime in real time in visible and terahertz ranges

    NASA Astrophysics Data System (ADS)

    Gerasimov, V. V.; Knyazev, B. A.; Cherkassky, V. S.

    2010-06-01

    An imaging attenuated total reflection (ATR) spectrometer for the terahertz range is created for the first time. The spectrometer uses a powerful free-electron laser. Images are recorded with a microbolom-eter detector array as a source of frequency tunable monochromatic radiation. Recording spectrally selective images of dynamic objects at a rate of 20 frames per second in the visible and terahertz ranges is demonstrated. In the terahertz range, images of the interdiffusion of liquids with strongly differing optical constants are obtained. Optimal configurations for the operation of the ATR spectrometer are found. Merits and demerits of the method are considered, as well as ways of improving the quality of image.

  6. Application of linear discriminant analysis and Attenuated Total Reflectance Fourier Transform Infrared microspectroscopy for diagnosis of colon cancer.

    PubMed

    Khanmohammadi, Mohammadreza; Bagheri Garmarudi, Amir; Samani, Simin; Ghasemi, Keyvan; Ashuri, Ahmad

    2011-06-01

    Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) microspectroscopy was applied for detection of colon cancer according to the spectral features of colon tissues. Supervised classification models can be trained to identify the tissue type based on the spectroscopic fingerprint. A total of 78 colon tissues were used in spectroscopy studies. Major spectral differences were observed in 1,740-900 cm(-1) spectral region. Several chemometric methods such as analysis of variance (ANOVA), cluster analysis (CA) and linear discriminate analysis (LDA) were applied for classification of IR spectra. Utilizing the chemometric techniques, clear and reproducible differences were observed between the spectra of normal and cancer cases, suggesting that infrared microspectroscopy in conjunction with spectral data processing would be useful for diagnostic classification. Using LDA technique, the spectra were classified into cancer and normal tissue classes with an accuracy of 95.8%. The sensitivity and specificity was 100 and 93.1%, respectively.

  7. Infrared analysis of polyethylene wear specimens using attenuated total reflection spectroscopy. [effects of radiation on the surface properties of materials for total joint protheses

    NASA Technical Reports Server (NTRS)

    Jones, W. R.; Lauer, J. L.

    1979-01-01

    Attenuated total reflection infrared spectroscopy was used to analyze ultrahigh molecular weight polyethylene wear test specimens. Three different specimens were analyzed. One specimen was gamma irradiated to a dose of 5.0 MRad, another to a dose of 2.5 MRad, and the final specimen was unirradiated. There was no conclusive evidence of chemical changes (i.e., unsaturation or oxidation) in the surface regions of any of the polyethylene samples. Therefore, it was concluded that the gamma irradiation sterilization procedure shoud not alter the boundary lubricating properties of the polyethylene.

  8. The Advantages of an Attenuated Total Internal Reflection Infrared Microspectroscopic Imaging Approach for Kidney Biopsy Analysis

    PubMed Central

    Gulley-Stahl, Heather J.; Bledsoe, Sharon B.; Evan, Andrew P.; Sommer, André J.

    2011-01-01

    The benefits of an ATR-FTIR imaging approach for kidney biopsy analysis are described. Biopsy sections collected from kidney stone formers are analyzed at the initial stages of stone development to provide insights into stone growth and formation. The majority of tissue analysis currently conducted with IR microspectroscopy is performed with a transflection method. The research presented in this manuscript demonstrates that ATR overcomes many of the disadvantages of transflection or transmission measurements for tissue analysis including an elimination of spectral artifacts. When kidney biopsies with small mineral inclusions are analyzed with a transflection approach, specular reflection, and the Christiansen effect (anomalous dispersion) can occur leading to spectral artifacts. Another effect specific to the analysis of mineral inclusions present in kidney biopsies is known as the reststrahlen effect where the inclusions become strong reflectors near an absorption band. ATR eliminates these effects by immersing the sample in a high index medium. Additionally, the focused beam size for ATR is decreased by a factor of four when a germanium internal reflection element is used, allowing the acquisition of spectra from small mineral inclusions several micrometers in diameter. If quantitative analysis of small mineral inclusions is ultimately desired, ATR provides the photometrically accurate spectra necessary for quantification. PMID:20132593

  9. Identification of trace additives in polymer materials by attenuated total reflection Fourier transform infrared mapping coupled with multivariate curve resolution

    NASA Astrophysics Data System (ADS)

    Li, Qian; Tang, Yongjiao; Yan, Zhiwei; Zhang, Pudun

    2017-06-01

    Although multivariate curve resolution (MCR) has been applied to the analysis of Fourier transform infrared (FTIR) imaging, it is still problematic to determine the number of components. The reported methods at present tend to cause the components of low concentration missed. In this paper a new idea was proposed to resolve this problem. First, MCR calculation was repeated by increasing the number of components sequentially, then each retrieved pure spectrum of as-resulted MCR component was directly compared with a real-world pixel spectrum of the local high concentration in the corresponding MCR map. One component was affirmed only if the characteristic bands of the MCR component had been included in its pixel spectrum. This idea was applied to attenuated total reflection (ATR)/FTIR mapping for identifying the trace additives in blind polymer materials and satisfactory results were acquired. The successful demonstration of this novel approach opens up new possibilities for analyzing additives in polymer materials.

  10. Attenuated total reflection response to wavelength tuning of plasmon-induced transparency in a metal-insulator-metal structure.

    PubMed

    Matsunaga, Kouki; Watanabe, Takeshi; Neo, Yoichiro; Matsumoto, Takahiro; Tomita, Makoto

    2016-11-15

    We experimentally demonstrated a plasmon-induced transparency in a metal-insulator-metal (MIM) structure based on the attenuated total reflection (ATR) response. Here, the MIM waveguide (MIMWG) mode and the surface plasmon polariton (SPP) resonance mode acted as low- and high-Q resonance modes, respectively. The dependence of the resonance angles of SPP and MIMWG mode resonances on the incident wavelength differed, which allowed the coupling condition between the two modes to be tuned via the wavelength. When the resonance angles of the two modes coincided, the ATR response showed a symmetric plasmon-induced transparency spectrum; in contrast, when the resonance angles were detuned, the ATR exhibited a sharp asymmetric spectrum characteristic to off-resonance Fano interference.

  11. Diagnosis of colon cancer by attenuated total reflectance-Fourier transform infrared microspectroscopy and soft independent modeling of class analogy.

    PubMed

    Khanmohammadi, Mohammadreza; Garmarudi, Amir Bagheri; Ghasemi, Keyvan; Jaliseh, Hadigheh Kazemi; Kaviani, Ahmad

    2009-01-01

    This study tries to demonstrate that attenuated total reflectance-fourier transform infrared (ATR-FTIR) microspectroscopy in combination with chemometric methods can reliably distinguish malignant colon tissues from healthy ones. It is important to explore a noninvasive and rapid method for detection of colon cancer biopsies. Initially, principal component analysis was applied to examine the degree of separation between tissue samples. Soft independent modeling of class analogy (SIMCA) was also employed to evaluate the prediction accuracy of ATR-FTIR microspectroscopy for the diagnosis of colon cancer. There were significant differences in the fourier transform infrared spectra of normal and cancerous colon biopsies in the 1,800-900 cm(-1) spectral region. The SIMCA results demonstrated that the accuracy, specificity, and sensitivity of the proposed diagnostic method were 93.3, 100, and 88.2%, respectively, which could help satisfy clinical diagnostic requirements.

  12. Identification of trace additives in polymer materials by attenuated total reflection Fourier transform infrared mapping coupled with multivariate curve resolution.

    PubMed

    Li, Qian; Tang, Yongjiao; Yan, Zhiwei; Zhang, Pudun

    2017-03-07

    Although multivariate curve resolution (MCR) has been applied to the analysis of Fourier transform infrared (FTIR) imaging, it is still problematic to determine the number of components. The reported methods at present tend to cause the components of low concentration missed. In this paper a new idea was proposed to resolve this problem. First, MCR calculation was repeated by increasing the number of components sequentially, then each retrieved pure spectrum of as-resulted MCR component was directly compared with a real-world pixel spectrum of the local high concentration in the corresponding MCR map. One component was affirmed only if the characteristic bands of the MCR component had been included in its pixel spectrum. This idea was applied to attenuated total reflection (ATR)/FTIR mapping for identifying the trace additives in blind polymer materials and satisfactory results were acquired. The successful demonstration of this novel approach opens up new possibilities for analyzing additives in polymer materials.

  13. Application of attenuated total reflectance Fourier transform infrared spectrometry to the determination of sodium percarbonate in washing powder detergent.

    PubMed

    Khanmohammadi, M; Kargosha, K

    2005-02-15

    In this paper, a novel and precise analytical procedure has been developed for quantitative determination of sodium percarbonate (SPC) in washing powder. The method is based on the partial least squares (PLS) treatment of data obtained by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectrometry in wavenumber region of 1435-1342cm(-1). The statistical parameters such as R(2), RSD, SEC and SECV have been evaluated, and number of factors, number of scan and the resolution have been optimized. In this method R(2) and RSD for five independent analyses of a 0.552g per 100g solution of SPC, SEC for 10 standard samples and SECV for five validation samples were 0.998, 1.011, 0.002 and 0.039 respectively. Results obtained for six different commercial washing powders compared well with those obtained with a standard method.

  14. From curdlan powder to the triple helix gel structure: an attenuated total reflection-infrared study of the gelation process.

    PubMed

    Gagnon, Marc-André; Lafleur, Michel

    2007-04-01

    Infrared spectroscopy was used to probe the hydration and gelation of curdlan, a linear polysaccharide built from repeating units of (1-->3)-beta-D-glucose. The spectra have been recorded using a temperature-controlled attenuated total reflection (ATR) device. Thermal gelation of curdlan could therefore be followed in situ and in real time. The transformation of the low-set gel, mainly formed with single helices, into a high-set gel, associated with a triple helix structure, could be directly observed. The relative intensities and positions of characteristic absorption bands in the C-O region (1200-850 cm-1) were found to be representative of the gel structure, as they are believed to be sensitive to the helical conformation of the polymer chains. Infrared (IR) spectroscopy is shown to be a useful tool for rapid and efficient characterization of curdlan gels.

  15. Micro-attenuated total reflection spectral imaging in archaeology: application to Maya paint and plaster wall decorations.

    PubMed

    Goodall, Rosemary A; Hall, Jay; Sharer, Robert J; Traxler, Loa; Rintoul, Llew; Fredericks, Peter M

    2008-01-01

    Fourier transform infrared (FT-IR) attenuated total reflection (ATR) imaging has been successfully used to identify individual mineral components of ancient Maya paint. The high spatial resolution of a micro FT-IR-ATR system in combination with a focal plane array detector has allowed individual particles in the paint to be resolved and identified from their spectra. This system has been used in combination with micro-Raman spectroscopy to characterize the paint, which was found to be a mixture of hematite and silicate particles with minor amounts of calcite, carbon, and magnetite particles in a sub-micrometer hematite and calcite matrix. The underlying stucco was also investigated and found to be a combination of calcite with fine carbon particles, making a dark sub-ground for the paint.

  16. Nature of hydrogen bonding of water molecules in aqueous solutions of glycerol by attenuated total reflection (ATR) infrared spectroscopy.

    PubMed

    Kataoka, Yuki; Kitadai, Norio; Hisatomi, Osamu; Nakashima, Satoru

    2011-04-01

    Attenuated total reflection infrared (ATR-IR) spectroscopy was performed on glycerol/water solutions in order to gain a better understanding of the strong hydrogen bonding of glycerol as a humectant. The OH stretching band after eliminating the contribution of glycerol OH in the glycerol/water solutions was decomposed using three Gaussian components. With increasing glycerol concentrations up to 50 volume %, the decrease of the 3428 cm(-1) component (middle H-bond component) and the increase of the 3562 cm(-1) component (longer H-bond component) suggested the breaking of H bonds among water molecules. On the other hand, the 3242 cm(-1) component (shorter H-bond component) remained unchanged. It was expected that water molecules surrounding glycerol molecules are retained by strong H bonding between H atoms of water and O atoms in C-O of glycerol when aqueous solutions containing glycerol are introduced in human skin. © 2011 Society for Applied Spectroscopy

  17. Micro-Attenuated Total Reflection Fourier Transform Infrared (Micro ATR FT-IR) Spectroscopic Imaging with Variable Angles of Incidence.

    PubMed

    Wrobel, Tomasz P; Vichi, Alessandra; Baranska, Malgorzata; Kazarian, Sergei G

    2015-10-01

    The control of the angle of incidence in attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy allows for the probing of the sample at different depths of penetration of the evanescent wave. This approach has been recently coupled with macro-imaging capability using a diamond ATR accessory. In this paper, the design of optical apertures for the micro-germanium (Ge) ATR objective is presented for an FT-IR spectroscopic imaging microscope, allowing measurements with different angles of incidence. This approach provides the possibility of three-dimensional (3D) profiling in micro-ATR FT-IR imaging mode. The proof of principle results for measurements of polymer laminate samples at different angles of incidence confirm that controlling the depth of penetration is possible using a Ge ATR objective with added apertures.

  18. Experimental study of the enhanced Raman scattering in the Sarid-type 4-layered attenuated total reflection configurations

    NASA Astrophysics Data System (ADS)

    Lee, Moon-Gyu; Lee, Jai-Hyung; Chang, Joon-Sung

    We experimentally explored the enhanced Raman scattering in pyridine (C 5H 5N) due to the excitation of long range surface plasmons (LRSP's) guided by a symmetrically bounded silver slab in the Sarid-type ATR (attenuated total reflection) configuration. We have observed that, with decreasing the metallic thickness, the absolute enhancement of the Raman cross section increases while the width of the polar angular distribution of the signal decreases. This observed dependence of the enhanced Raman intensity on the thickness of the thin Ag slab and the collecting solid angle is well explained by assuming that the Raman scattering is mediated by LRSP's. The observed maximum enhancement factor is 4 × 10 6 for the 140 Å silver slab which agrees well with the theoretically predicted value of 6 × 10 6.

  19. Chemometric analysis of attenuated total reflectance infrared spectra of Proteus mirabilis strains with defined structures of LPS.

    PubMed

    Zarnowiec, Paulina; Mizera, Andrzej; Chrapek, Magdalena; Urbaniak, Mariusz; Kaca, Wieslaw

    2016-07-01

    Proteus spp. strains are some of the most important pathogens associated with complicated urinary tract infections and bacteremia affecting patients with immunodeficiency and long-term urinary catheterization. For epidemiological purposes, various molecular typing methods have been developed for this pathogen. However, these methods are labor intensive and time consuming. We evaluated a new method of differentiation between strains. A collection of Proteus spp. strains was analyzed by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy in the mid-infrared region. ATR FT-IR spectroscopy used in conjunction with a diamond ATR accessory directly produced the biochemical profile of the surface chemistry of bacteria. We conclude that a combination of ATR FT-IR spectroscopy and mathematical modeling provides a fast and reliable alternative for discrimination between Proteus isolates, contributing to epidemiological research. © The Author(s) 2016.

  20. Historical perspective and modern applications of Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR).

    PubMed

    Blum, Marc-Michael; John, Harald

    2012-01-01

    Vibrational spectroscopy has a long history as an important spectroscopic method in chemical and pharmaceutical analysis. Instrumentation for infrared (IR) spectroscopy was revolutionized by the introduction of Fourier Transform Infrared (FTIR) spectrometers. In addition, easier sampling combined with better sample-to-sample reproducibility and user-to-user spectral variation became available with attenuated total reflectance (ATR) probes and their application for in situ IR spectroscopy. These innovations allow many new applications in chemical and pharmaceutical analysis, such as the use of IR spectroscopy in Process Analytical Chemistry (PAC), the quantitation of drugs in complex matrix formulations, the analysis of protein binding and function and in combination with IR microscopy to the emergence of IR imaging technologies. The use of ATR-FTIR instruments in forensics and first response to 'white powder' incidents is also discussed. A short overview is given in this perspective article with the aim to renew and intensify interest in IR spectroscopy.

  1. Individual sugar content control by the use of FTIR spectroscopy coupled with an attenuated total reflectance accessory

    NASA Astrophysics Data System (ADS)

    Bellon, Veronique; Vallat, Celine

    1993-12-01

    This paper describes the use of Fourier Transform Infrared (FT-IR) spectroscopy coupled with an Attenuated Total Reflectance (ATR) accessory to quantify the individual sugars (glucose, maltose, maltodextrins...) in a mixture extracted from a process of wheat transformation into sugar. ATR accessory allows us to analyze very viscous media such as molasses by pouring the medium on a flat crystal. In the first step, model mixtures are prepared in the concentrations common to sugar industries and are analyzed by an FT-IR spectrometer. Binary (glucose/maltose) and ternary (glucose/maltose/maltotriose) solutions are used. Spectra are recorded from 1300 to 850 cm-1. Multivariate mathematical processing methods are applied to these spectra (Partial Least Squares and Principal Component Regression). The results show a very good discrimination between the different sugars.

  2. High-Throughput Thermal Stability Analysis of a Monoclonal Antibody by Attenuated Total Reflection FT-IR Spectroscopic Imaging

    PubMed Central

    2014-01-01

    The use of biotherapeutics, such as monoclonal antibodies, has markedly increased in recent years. It is thus essential that biotherapeutic production pipelines are as efficient as possible. For the production process, one of the major concerns is the propensity of a biotherapeutic antibody to aggregate. In addition to reducing bioactive material recovery, protein aggregation can have major effects on drug potency and cause highly undesirable immunological effects. It is thus essential to identify processing conditions which maximize recovery while avoiding aggregation. Heat resistance is a proxy for long-term aggregation propensity. Thermal stability assays are routinely performed using various spectroscopic and scattering detection methods. Here, we evaluated the potential of macro attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopic imaging as a novel method for the high-throughput thermal stability assay of a monoclonal antibody. This chemically specific visualization method has the distinct advantage of being able to discriminate between monomeric and aggregated protein. Attenuated total reflection is particularly suitable for selectively probing the bottom of vessels, where precipitated aggregates accumulate. With focal plane array detection, we tested 12 different buffer conditions simultaneously to assess the effect of pH and ionic strength on protein thermal stability. Applying the Finke model to our imaging kinetics allowed us to determine the rate constants of nucleation and autocatalytic growth. This analysis demonstrated the greater stability of our immunoglobulin at higher pH and moderate ionic strength, revealing the key role of electrostatic interactions. The high-throughput approach presented here has significant potential for analyzing the stability of biotherapeutics as well as any other biological molecules prone to aggregation. PMID:25221926

  3. Surface plasmons in doped graphene excited by the Attenuated Total Reflection technique in the THz regime

    NASA Astrophysics Data System (ADS)

    Ramos-Mendieta, F.; Hernandez-Lopez, J. A.; Palomino-Ovando, M.

    2015-03-01

    Surface plasmons of transverse electric (TE) and transverse magnetic (TM) polarization in doped free-standing graphene are numerically investigated at THz frequencies. For detecting these modes sufficient sensitivity of the prism-based Otto configuration is demonstrated. Complete agreement with the TM dispersion relation is found in doped graphene of Fermi level μ = 0.8 eV; perfect absorption due to wave interference is also observed. On the other hand, TE surface plasmons are special surface vibrations without induced surface charge; they are self-sustained current oscillations (unique of graphene) that arise in frequency ranges where the imaginary part of the graphene dynamical conductivity is negative. We found that TE plasmons are excited for angles of incidence very close to the critical angle between prism and air, as predicted from their dispersion relation. Reflection profiles and field intensities of these waves are presented for μ = 0.2, 0.3 eV. This work was supported by SESIC Mexico, Promep Grant FOFM-2008 and by CONACyT, Mexico.

  4. Determination of antioxidant capacity and phenolic content of chocolate by attenuated total reflectance-Fourier transformed-infrared spectroscopy.

    PubMed

    Hu, Yaxi; Pan, Zhi Jie; Liao, Wen; Li, Jiaqi; Gruget, Pierre; Kitts, David D; Lu, Xiaonan

    2016-07-01

    Antioxidant capacity and phenolic content of chocolate, containing different amounts of cacao (35-100%), were determined using attenuated total reflectance (ATR)-Fourier transformed-infrared (FT-IR) spectroscopy (4000-550cm(-1)). Antioxidant capacities were first characterized using DPPH (2,2-diphenyl-1-picrylhydrazyl) and ORAC (oxygen radical absorbance capacity) assays. Phenolic contents, including total phenol and procyanidins monomers, were quantified using the Folin-Ciocalteu assay and high performance liquid chromatography coupled with photodiode array detector (HPLC-DAD), respectively. Five partial least-squares regression (PLSR) models were constructed and cross-validated using FT-IR spectra from 18 types of chocolate and corresponding reference values determined using DPPH, ORAC, Folin-Ciocalteu, and HPLC assays. The models were validated using seven unknown samples of chocolate. PLSR models showed good prediction capability for DPPH [R(2)-P (prediction)=0.88, RMSEP (root mean squares error of prediction)=12.62μmol Trolox/g DFW], ORAC (R(2)-P=0.90, RMSEP=37.92), Folin-Ciocalteu (R(2)-P=0.88, RMSEP=5.08), and (+)-catechin (R(2)-P=0.86, RMSEP=0.10), but lacked accuracy in the prediction of (-)-epicatechin (R(2)-P=0.72, RMSEP=0.57). ATR-FT-IR spectroscopy can be used for rapid prediction of antioxidant capacity, total phenolic content, and (+)-catechin in chocolate.

  5. [Classification of oils by attenuated total reflectance-Fourier transform infrared spectrometry combined with pattern recognition techniques].

    PubMed

    Liu, Qian; Sun, Pei-Yan; Gao, Zhen-Hui; Cai, Wen-Sheng; Shao, Xue-Guang

    2010-03-01

    In the present work, the combination of attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR) and pattern recognition, including principal components analysis (PCA) and hierarchical cluster analysis (HCA), is used as a fast and convenient analytical tool to classify oil samples. Twenty five samples including crude oils and fuel oils with different total contents of n-alkanes were analyzed. It was found that multiplicative scatter correction (MSC) and continuous wavelet transform (CWT) as a pretreatment method could improve the classification results of pattern recognition. The classification results were proved to be in agreement with the origin of the oil samples. The oils with high content of n-alkanes and those with low content were classified clearly by this developed method, but it still had some constraint to differentiating oils with little difference. The present work provides a feasible method for quick classification of oils, which can be used for the initial identification of spill oils and afford useful information for the further identification of the oils.

  6. Attenuated Total Reflection Mid-Infrared (ATR-MIR) Spectroscopy and Chemometrics for the Identification and Classification of Commercial Tannins.

    PubMed

    Ricci, Arianna; Parpinello, Giuseppina P; Olejar, Kenneth J; Kilmartin, Paul A; Versari, Andrea

    2015-11-01

    Attenuated total reflection Fourier transform infrared (FT-IR) spectroscopy was used to characterize 40 commercial tannins, including condensed and hydrolyzable chemical classes, provided as powder extracts from suppliers. Spectral data were processed to detect typical molecular vibrations of tannins bearing different chemical groups and of varying botanical origin (univariate qualitative analysis). The mid-infrared region between 4000 and 520 cm(-1) was analyzed, with a particular emphasis on the vibrational modes in the fingerprint region (1800-520 cm(-1)), which provide detailed information about skeletal structures and specific substituents. The region 1800-1500 cm(-1) contained signals due to hydrolyzable structures, while bands due to condensed tannins appeared at 1300-900 cm(-1) and exhibited specific hydroxylation patterns useful to elucidate the structure of the flavonoid monomeric units. The spectra were investigated further using principal component analysis for discriminative purposes, to enhance the ability of infrared spectroscopy in the classification and quality control of commercial dried extracts and to enhance their industrial exploitation.

  7. Surface-modified ZnSe waveguides for label-free infrared attenuated total reflection detection of DNA hybridization.

    PubMed

    Riccardi, Carla S; Hess, Dennis W; Mizaikoff, Boris

    2011-12-07

    This communication presents a novel label-free biosensing method to monitor DNA hybridization via infrared attenuated total reflection (IR-ATR) spectroscopy using surface-modified ZnSe waveguides. Well-defined carboxyl-terminated monolayers were formed at H-terminated ZnSe by direct photochemical activation. Chemical activation of the acidic function was obtained by using succinimide/carbodiimide linkers. The sequential surface modification reactions were characterized by XPS and IR-ATR spectroscopy. Finally, a single stranded DNA probe with a C6-NH(2) 5' modifier was coupled to the ester-terminated surface via peptide bonding, and the hybridization of the immobilized DNA sequence with its complementary strand was directly evaluated by IR-ATR spectroscopy in the mid-infrared (MIR) spectral regime (3-20 μm) without requiring an additional label. A shift of the vibrational modes corresponding to the phosphodiester and deoxyribose structures of the DNA backbone was observed. Hence, this approach substantiates a novel strategy for label-free DNA detection utilizing mid-infrared spectroscopy as the optical sensing platform.

  8. Determination of molecular anisotropy in thin films of discotic assemblies using attenuated total reflectance UV-visible spectroscopy.

    PubMed

    Flora, Ware H; Mendes, Sergio B; Doherty, Walter J; Saavedra, S Scott; Armstrong, Neal R

    2005-01-04

    We report here an investigation of absorbance anisotropy in highly ordered, single bilayer (ca. 5.6 nm) Langmuir-Blodgett (LB) thin films of discotic liquid-crystalline phthalocyanines, using a recently introduced broad-band attenuated total reflectance (ATR) spectroscopic technique, capable of measuring dichroism in such films in the UV--visible optical region down to absorbances of ca. 0.003 absorbance units. On the basis of the ATR measurements of LB-deposited films, a thorough treatment was established to determine the ensemble average of the Cartesian components and the associated optical anisotropy of transition dipoles in the molecular film. In an effort to recover order parameters of molecular orientation, those results were interpreted with a circular dipole model, which is the expected model for the isolated molecule based on symmetry properties. We measured a strong dipole component normal to the film plane that cannot be explained in terms of a truly circular model, indicating that the molecular transition dipoles were perturbed upon aggregation. The utility of the experimental approach was further demonstrated by (a) investigating the effect of substrate modifiers (methyl- and phenyl-terminated silanes) on the ordering within the phthalocyanine film and (b) the effect of water immersion and re-annealing of the thin film on molecular ordering and optical anisotropy.

  9. Quantitative analysis of sulfathiazole polymorphs in ternary mixtures by attenuated total reflectance infrared, near-infrared and Raman spectroscopy.

    PubMed

    Hu, Yun; Erxleben, Andrea; Ryder, Alan G; McArdle, Patrick

    2010-11-02

    The simultaneous quantitative analysis of sulfathiazole polymorphs (forms I, III and V) in ternary mixtures by attenuated total reflectance-infrared (ATR-IR), near-infrared (NIR) and Raman spectroscopy combined with multivariate analysis is reported. To reduce the effect of systematic variations, four different data pre-processing methods; multiplicative scatter correction (MSC), standard normal variate (SNV), first and second derivatives, were applied and their performance was evaluated using their prediction errors. It was possible to derive a reliable calibration model for the three polymorphic forms, in powder ternary mixtures, using a partial least squares (PLS) algorithm with SNV pre-processing, which predicted the concentration of polymorphs I, III and V. Root mean square errors of prediction (RMSEP) for ATR-IR spectra were 5.0%, 5.1% and 4.5% for polymorphs I, III and V, respectively, while NIR spectra had a RMSEP of 2.0%, 2.9%, and 2.8% and Raman spectra had a RMSEP of 3.5%, 4.1%, and 3.6% for polymorphs I, III and V, respectively. NIR spectroscopy exhibits the smallest analytical error, higher accuracy and robustness. When these advantages are combined with the greater convenience of NIR's "in glass bottle" sampling method both ATR-IR and Raman methods appear less attractive.

  10. Waveband selection of reagent-free determination for thalassemia screening indicators using Fourier transform infrared spectroscopy with attenuated total reflection.

    PubMed

    Long, Xiaoli; Liu, Guisong; Pan, Tao; Chen, Jiemei

    2014-08-01

    A reagent-free determination method for the thalassemia screening indicators hemoglobin (Hb), mean corpuscular Hb (MCH), and mean corpuscular volume (MCV) was developed based on Fourier transform infrared spectrometers equipped with an attenuated total reflection accessory. A random and stability-dependent rigorous process of calibration, prediction, and validation was conducted. Appropriate wavebands were selected using the improved moving window partial least squares method with stability and equivalence. The obtained optimal wavebands were 1722 to 1504 cm⁻¹ for Hb, 1653 to 901 cm⁻¹ for MCH, and 1562 to 964 cm⁻¹ for MCV. A model set equivalent to the optimal model was proposed for each indicator; the public waveband of Hb equivalent wavebands was 1717 to 1510 cm⁻¹, and the public equivalent waveband for MCH and MCV was 1562 to 901 cm⁻¹. All selected wavebands were within the MIR fingerprint region and achieved high validation effects. The sensitivity and specificity were 100.0% and 96.9% for the optimal wavebands and 100.0% and 95.3% for the equivalent wavebands, respectively. Thus, the spectral prediction was highly accurate for determining negative and positive for thalassemia screening. This technique is rapid and simple in comparison with conventional methods and is a promising tool for thalassemia screening in large populations.

  11. An examination of the sequence of intersecting lines using attenuated total reflectance-Fourier transform infrared spectral imaging.

    PubMed

    Bojko, Katherine; Roux, Claude; Reedy, Brian J

    2008-11-01

    In this study, the potential of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectral imaging as a technique to determine the sequence of line crossings was examined. The technique was successful in determining the sequence of heterogeneous line intersections produced using ballpoint pens and laser printers. By imaging at characteristic frequencies, it was possible to form spectral images showing the spatial distribution of the materials. By examining the spectral images from the inks, it was possible to determine whether the ink was above or below the toner. In blind testing, ATR-FTIR spectral imaging results were directly compared to those obtained by eight experienced forensic document examiners using methods regularly employed in casework. ATR-FTIR spectral imaging was shown to achieve a 100% success rate in the blind tests, whereas some incorrect sequence determinations were made by the forensic document examiners when using traditional techniques. The technique was unable to image ink-jet printing, gel pens, roller ball pens, and felt-tip pens, and was also unable to determine the sequence of intersecting ballpoint pen lines.

  12. Evaluating degradation of silk's fibroin by attenuated total reflectance infrared spectroscopy: case study of ancient banners from Polish collections.

    PubMed

    Koperska, M A; Łojewski, T; Łojewska, J

    2015-01-25

    In this study a part of research where artificially aged model samples were used as a guideline to the mechanism of degradation is presented. In previous work Bombyx Mori silk samples were exposed to various environments such as different oxygen, water vapour and volatile organic products content, all at the temperature of 150 °C [11]. Based on those results gathered with by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR-FTIR) the degradation estimators were proposed and classified as follows: (1) Primary functional groups estimators EAmideI/II - intensity ratios of Amide I C=O stretching vibration to Amide II N-H in-plane bending and C-N stretching vibrations A1620/A1514. ECOOH - band 1318 cm(-1) integral to band integral of CH3 bending vibration band located at 1442 cm(-1)P1318/P1442. (2) Secondary conformational estimators EcC=O2 - intensity ratios within Amide I C=O stretching vibration of parallel β-sheet to antiparallel β-sheet A1620/A1699. In this work estimators were verified against estimators calculated from spectra of silk samples from 8 museum objects: 3 from 19th, 2 from 18th, 1 from 17th and 2 from 16th century including 3 banners from the storage resources of the Wawel Royal Castle in Cracow, Poland.

  13. In situ attenuated total reflection FTIR investigations of thin water films in the silanization of ZnSe and Si

    NASA Astrophysics Data System (ADS)

    Imhof, Roman; Xie, Xianyue; Calzaferri, Gion

    1997-07-01

    In situ attenuated total reflection ATR-FTIR spectroscopy is used to investigate the reaction of trimethylchlorosilane (CH 3) 3SiCl in organic solvents at room temperature on ZnSe and on Si surfaces in the presence and absence of pyridine. In the absence of the base, siloxanes are formed, but they can be removed in situ with the reaction solvent along with the surplus of trimethylchlorosilane and no chemisorption is detected. Instead a thin water film is formed on the surface which shows a well resolved ATR-IR water spectrum with absorptions νas( O H) at 3477 cm -1, νs( O H) at 3421 cm -1, 2δ(HOH) at 3186 cm -1, δ(HOH) + νL at 2182 cm -1 where νL is a librational mode of water and δ(HOH) at 1601 cm -1. These thin water films are astonishingly stable and easy to handle, and their growth can be monitored. Addition of pyridine to the reaction solvent allows the detection of trimethylsilanol with an absorption band at 3706 cm -1. Concurrently pyridinium chloride is formed and partly precipitates on the substrate surface.

  14. The Advantages of an Attenuated Total Internal Reflection Infrared Microspectroscopic Imaging Technique for the Analysis of Polymer Laminates.

    PubMed

    Ling, Chen; Sommer, André J

    2015-06-01

    Until recently, the analysis of polymer laminates using infrared microspectroscopy involved the painstaking separation of individual layers by dissection or by obtaining micrometer thin cross-sections. The latter usually requires the expertise of an individual trained in microtomy and even then, the very structure of the laminate could affect the outcome of the spectral results. The recent development of attenuated total internal reflection (ATR) infrared microspectroscopy imaging has provided a new avenue for the analysis of these multilayer structures. This report compares ATR infrared microspectroscopy imaging with conventional transmission infrared microspectroscopy imaging. The results demonstrate that the ATR method offers improved spatial resolution, eliminates a variety of competing optical processes, and requires minimal sample preparation relative to transmission measurements. These advantages were illustrated using a polymer laminate consisting of 11 different layers whose thickness ranged in size from 4-20 μm. The spatial resolution achieved by using an ATR-FTIR (Fourier transform infrared spectroscopy) imaging technique was diffraction limited. Contrast in the ATR images was enhanced by principal component analysis.

  15. Attenuated total reflectance infrared spectroscopy study of hysteresis of water and n-alcohol coadsorption on silicon oxide.

    PubMed

    Barnette, Anna L; Kim, Seong H

    2012-11-06

    The structure and thickness of the binary adsorbate layers formed on silicon oxide exposed in n-propanol/water and n-pentanol/water vapor mixtures under atmospheric pressure and room temperature conditions were investigated using attenuated total reflectance infrared spectroscopy (ATR-IR). The ATR-IR spectra of the adsorbate layers were analyzed while the vapor composition was varied stepwise by changing the mixing ratios of (a) n-propanol vapor stream with a 94% relative partial pressure (P/P(sat)) and 94% P/P(sat) water stream and (b) 83% P/P(sat)n-pentanol and 85% P/P(sat) water streams. The amount of the adsorbed water with solid-like structure in the binary adsorbate layer was larger in successive cycles of the water/alcohol vapor composition change, while n-alcohol showed negligible hysteresis in the amount adsorbed. The hysteresis behavior of the solid-like water structure was amplified in the coadsorption cycles of alcohol and water as compared to the water-only case. The origin of this behavior must be attributed to the structure of the alcohol/water binary adsorbate layer. The n-alcohol molecules present at the adsorbate/vapor interface can lower the surface energy of the system and stabilize the solid-like water structure in the alcohol-water binary adsorbate layer on silicon oxide.

  16. Evaluating degradation of silk's fibroin by attenuated total reflectance infrared spectroscopy: Case study of ancient banners from Polish collections

    NASA Astrophysics Data System (ADS)

    Koperska, M. A.; Łojewski, T.; Łojewska, J.

    2015-01-01

    In this study a part of research where artificially aged model samples were used as a guideline to the mechanism of degradation is presented. In previous work Bombyx Mori silk samples were exposed to various environments such as different oxygen, water vapour and volatile organic products content, all at the temperature of 150 °C [11]. Based on those results gathered with by Attenuated Total Reflectance/Fourier Transform Infrared Spectroscopy (ATR-FTIR) the degradation estimators were proposed and classified as follows: Primary functional groups estimators EAmideI/II - intensity ratios of Amide I Cdbnd O stretching vibration to Amide II Nsbnd H in-plane bending and Csbnd N stretching vibrations A1620/A1514. ECOOH - band 1318 cm-1 integral to band integral of CH3 bending vibration band located at 1442 cm-1P1318/P1442. Secondary conformational estimators EcCdbndO2 - intensity ratios within Amide I Cdbnd O stretching vibration of parallel β-sheet to antiparallel β-sheet A1620/A1699. In this work estimators were verified against estimators calculated from spectra of silk samples from 8 museum objects: 3 from 19th, 2 from 18th, 1 from 17th and 2 from 16th century including 3 banners from the storage resources of the Wawel Royal Castle in Cracow, Poland.

  17. Screening of Wolbachia endosymbiont infection in Aedes aegypti mosquitoes using Attenuated Total Reflection mid-infrared spectroscopy.

    PubMed

    Khoshmanesh, Aazam; Christensen, Dale; Perez-Guaita, David; Iturbe-Ormaetxe, Iñaki; O'Neill, Scott L; McNaughton, Don; Wood, Bayden R

    2017-03-23

    Dengue fever is the most common mosquito transmitted viral infection afflicting humans, estimated to generate around 390 million infections each year in over 100 countries. The introduction of the endosymbiotic bacterium Wolbachia into Aedes aegypti mosquitoes has the potential to greatly reduce the public health burden of the disease. This approach requires extensive PCR (Polymerase Chain Reaction) testing of the Wolbachia-infection status of mosquitoes in areas where Wolbachia-A. aegypti are released. Here we report the first example of small organism mid-infrared spectroscopy where we have applied Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy and multivariate modelling methods to determine sex, age and the presence of Wolbachia (wMel strain) in laboratory mosquitoes and sex and age in field mosquitoes. The prediction errors using Partial Least Squares Discriminant Analysis (PLS-DA) discrimination models for laboratory studies on independent test sets ranged from 0 to 3% for age & sex grading, and 3 to 5% for Wolbachia infection diagnosis using dry mosquito abdomens while field study results using an Artificial neural network yielded a 10 % error. The application of FTIR analysis is inexpensive, easy to use, portable, and shows significant potential to replace the reliance on more expensive and laborious PCR assays.

  18. In situ permeation study of drug through the stratum corneum using attenuated total reflection Fourier transform infrared spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Andanson, Jean-Michel; Hadgraft, Jonathan; Kazarian, Sergei G.

    2009-05-01

    Infrared (IR) spectroscopy is one of the most chemically specific analytical methods that gives information about composition, structure, and interactions in a material. IR spectroscopy has been successfully applied to study the permeation of xenobiotics through the skin. Combining IR spectroscopy with an IR array detector led to the development of Fourier transform infrared (FTIR) spectroscopic imaging, which generates chemical information from different areas of a sample at the microscopic level. This is particularly important for heterogeneous samples, such as skin. Attenuated total reflection (ATR)-FTIR imaging has been applied to measure, in situ, the diffusion of benzyl nicotinate (BN) through the outer layer of human skin [stratum corneum (SC)]. In vitro experiments have demonstrated the heterogeneous distribution of SC surface lipids before the penetration of a saturated solution of BN. Image analysis demonstrated a strong correlation between the distribution of lipids and drugs, while ethanol appeared to be homogenously distributed in the SC. These results show the ability of ATR-FTIR imaging to measure simultaneously the affinities of drug and solvent to the lipid-rich and lipid-poor skin domains, respectively, during permeation. This information may be useful in better understanding drug-diffusion pathways through the SC.

  19. Structure and Thermotropic phase Behavior of Fluorinated Phospholipid Bilayers: A combined Attenuated Total Reflection FTIR Spectroscopy and Imaging Ellipsometry Study

    PubMed Central

    Schuy, Steffen; Faiss, Simon; Yoder, Nicholas C.; Kalsani, Venkateshwarlu; Kumar, Krishna; Janshoff, Andreas; Vogel, Reiner

    2008-01-01

    Lipid bilayers consisting of lipids with terminally perfluoroalkylated chains have remarkable properties. They exhibit increased stability and phase-separated nanoscale patterns in mixtures with nonfluorinated lipids. In order to understand the bilayer properties that are responsible for this behavior, we have analyzed the structure of solid-supported bilayers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and of a DPPC analogue with 6 terminal perfluorinated methylene units (F6-DPPC). Polarized attenuated total reflection Fourier-transform infrared spectroscopy indicates that for F6-DPPC, the tilt of the lipid acyl chains to the bilayer normal is increased to 39° as compared to 21° for native DPPC, for both lipids in the gel phase. This substantial increase of the tilt angle is responsible for a decrease of the bilayer thickness from 5.4 nm for DPPC to 4.5 nm for F6-DPPC, as revealed by temperature-controlled imaging ellipsometry on microstructured lipid bilayers and solution atomic force microscopy. During the main phase transition from the gel to the fluid phase, both the relative bilayer thickness change and the relative area change are substantially smaller for F6-DPPC than for DPPC. In light of these structural and thermotropic data, we propose a model in which the higher acyl-chain tilt angle in F6-DPPC is the result of a conformational rearrangement to minimize unfavorable fluorocarbon–hydrocarbon interactions in the center of the bilayer due to chain staggering. PMID:18563929

  20. Concept and setup for intraoperative imaging of tumorous tissue via Attenuated Total Reflection spectrosocopy with Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Geiger, Florian B.; Koerdel, Martin; Schick, Anton; Heimann, Axel; Matiasek, Kaspar; Herkommer, Alois M.

    2015-03-01

    A major challenge in tumor surgery is the differentiation between normal and malignant tissue. Since an incompletely resected tumor easily leads to recidivism, the gold standard is to remove malignant tissue with a sufficient safety margin and send it to pathology for examination with patho-histological techniques (rapid section diagnosis). This approach, however, exhibits several disadvantages: The removal of additional tissue (safety margin) means additional stress to the patient; the correct interpretation of proper tumor excision relies on the pathologist's experience and the waiting time between resection and pathological result can be more than 45 minutes. This last aspect implies unnecessary occupation of cost-intensive operating room staff as well as longer anesthesia for the patient. Various research groups state that hyperspectral imaging in the mid-infrared, especially in the so called "fingerprint region", allows spatially resolved discrimination between normal and malignant tissue. All these experiments, though, took place in a laboratory environment and were conducted on dried, ex vivo tissue and on a microscopic scale. It is therefore our aim to develop a system incorporating the following properties: Intraoperatively and in vivo applicable, measurement time shorter than one minute, based on mid infrared spectroscopy, providing both spectral and spatial information and no use of external fluorescence markers. Theoretical assessment of different concepts and experimental studies show that a setup based on a tunable Quantum Cascade Laser and Attenuated Total Reflection seems feasible for in vivo tissue discrimination via imaging. This is confirmed by experiments with a first demonstrator.

  1. Rapid quantification of methamphetamine: using attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) and chemometrics.

    PubMed

    Hughes, Juanita; Ayoko, Godwin; Collett, Simon; Golding, Gary

    2013-01-01

    In Australia and increasingly worldwide, methamphetamine is one of the most commonly seized drugs analysed by forensic chemists. The current well-established GC/MS methods used to identify and quantify methamphetamine are lengthy, expensive processes, but often rapid analysis is requested by undercover police leading to an interest in developing this new analytical technique. Ninety six illicit drug seizures containing methamphetamine (0.1%-78.6%) were analysed using Fourier Transform Infrared Spectroscopy with an Attenuated Total Reflectance attachment and Chemometrics. Two Partial Least Squares models were developed, one using the principal Infrared Spectroscopy peaks of methamphetamine and the other a Hierarchical Partial Least Squares model. Both of these models were refined to choose the variables that were most closely associated with the methamphetamine % vector. Both of the models were excellent, with the principal peaks in the Partial Least Squares model having Root Mean Square Error of Prediction 3.8, R(2) 0.9779 and lower limit of quantification 7% methamphetamine. The Hierarchical Partial Least Squares model had lower limit of quantification 0.3% methamphetamine, Root Mean Square Error of Prediction 5.2 and R(2) 0.9637. Such models offer rapid and effective methods for screening illicit drug samples to determine the percentage of methamphetamine they contain.

  2. Identification of fungal phytopathogens using Fourier transform infrared-attenuated total reflection spectroscopy and advanced statistical methods

    NASA Astrophysics Data System (ADS)

    Salman, Ahmad; Lapidot, Itshak; Pomerantz, Ami; Tsror, Leah; Shufan, Elad; Moreh, Raymond; Mordechai, Shaul; Huleihel, Mahmoud

    2012-01-01

    The early diagnosis of phytopathogens is of a great importance; it could save large economical losses due to crops damaged by fungal diseases, and prevent unnecessary soil fumigation or the use of fungicides and bactericides and thus prevent considerable environmental pollution. In this study, 18 isolates of three different fungi genera were investigated; six isolates of Colletotrichum coccodes, six isolates of Verticillium dahliae and six isolates of Fusarium oxysporum. Our main goal was to differentiate these fungi samples on the level of isolates, based on their infrared absorption spectra obtained using the Fourier transform infrared-attenuated total reflection (FTIR-ATR) sampling technique. Advanced statistical and mathematical methods: principal component analysis (PCA), linear discriminant analysis (LDA), and k-means were applied to the spectra after manipulation. Our results showed significant spectral differences between the various fungi genera examined. The use of k-means enabled classification between the genera with a 94.5% accuracy, whereas the use of PCA [3 principal components (PCs)] and LDA has achieved a 99.7% success rate. However, on the level of isolates, the best differentiation results were obtained using PCA (9 PCs) and LDA for the lower wavenumber region (800-1775 cm-1), with identification success rates of 87%, 85.5%, and 94.5% for Colletotrichum, Fusarium, and Verticillium strains, respectively.

  3. Application of multibounce attenuated total reflectance fourier transform infrared spectroscopy and chemometrics for determination of aspartame in soft drinks.

    PubMed

    Khurana, Harpreet Kaur; Cho, Il Kyu; Shim, Jae Yong; Li, Qing X; Jun, Soojin

    2008-02-13

    Aspartame is a low-calorie sweetener commonly used in soft drinks; however, the maximum usage dose is limited by the U.S. Food and Drug Administration. Fourier transform infrared (FTIR) spectroscopy with attenuated total reflectance sampling accessory and partial least-squares regression (PLS) was used for rapid determination of aspartame in soft drinks. On the basis of spectral characterization, the highest R2 value, and lowest PRESS value, the spectral region between 1600 and 1900 cm(-1) was selected for quantitative estimation of aspartame. The potential of FTIR spectroscopy for aspartame quantification was examined and validated by the conventional HPLC method. Using the FTIR method, aspartame contents in four selected carbonated diet soft drinks were found to average from 0.43 to 0.50 mg/mL with prediction errors ranging from 2.4 to 5.7% when compared with HPLC measurements. The developed method also showed a high degree of accuracy because real samples were used for calibration, thus minimizing potential interference errors. The FTIR method developed can be suitably used for routine quality control analysis of aspartame in the beverage-manufacturing sector.

  4. Detection and identification of explosive particles in fingerprints using attenuated total reflection-Fourier transform infrared spectromicroscopy.

    PubMed

    Mou, Yongyan; Rabalais, J Wayne

    2009-07-01

    The application of attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectromicroscopy for detection of explosive particles in fingerprints is described. The combined functions of ATR-FTIR spectromicroscopy are visual searching of particles in fingerprints and measuring the FTIR spectra of the particles. These functions make it possible to directly identify whether a suspect has handled explosives from the fingerprints alone. Particles in explosive contaminated fingerprints are either ingredients of the explosives, finger residues, or other foreign materials. These cannot normally be discriminated by their morphology alone. ATR-FTIR spectra can provide both particle morphology and composition. Fingerprints analyzed by ATR-FTIR can be used for further analysis and identification because of its non-destructive character. Fingerprints contaminated with three different types of explosives, or potential explosives, have been analyzed herein. An infrared spectral library was searched in order to identify the explosive residues. The acquired spectra are compared to those of finger residue alone, in order to differentiate such residue from explosive residue.

  5. Rapid Quantification of Methamphetamine: Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Chemometrics

    PubMed Central

    Hughes, Juanita; Ayoko, Godwin; Collett, Simon; Golding, Gary

    2013-01-01

    In Australia and increasingly worldwide, methamphetamine is one of the most commonly seized drugs analysed by forensic chemists. The current well-established GC/MS methods used to identify and quantify methamphetamine are lengthy, expensive processes, but often rapid analysis is requested by undercover police leading to an interest in developing this new analytical technique. Ninety six illicit drug seizures containing methamphetamine (0.1%–78.6%) were analysed using Fourier Transform Infrared Spectroscopy with an Attenuated Total Reflectance attachment and Chemometrics. Two Partial Least Squares models were developed, one using the principal Infrared Spectroscopy peaks of methamphetamine and the other a Hierarchical Partial Least Squares model. Both of these models were refined to choose the variables that were most closely associated with the methamphetamine % vector. Both of the models were excellent, with the principal peaks in the Partial Least Squares model having Root Mean Square Error of Prediction 3.8, R2 0.9779 and lower limit of quantification 7% methamphetamine. The Hierarchical Partial Least Squares model had lower limit of quantification 0.3% methamphetamine, Root Mean Square Error of Prediction 5.2 and R2 0.9637. Such models offer rapid and effective methods for screening illicit drug samples to determine the percentage of methamphetamine they contain. PMID:23936058

  6. Direct determination of lycopene content in tomatoes (Lycopersicon esculentum) by attenuated total reflectance infrared spectroscopy and multivariate analysis.

    PubMed

    Halim, Yuwana; Schwartz, Steven J; Francis, David; Baldauf, Nathan A; Rodriguez-Saona, Luis E

    2006-01-01

    Lycopene is a potent antioxidant that has been shown to play critical roles in disease prevention. Efficient assays for detection and quantification of lycopene are desirable as alternatives to time- and labor-intensive methods. Attenuated total reflectance infrared (ATR-IR) spectroscopy was used for quantification of lycopene in tomato varieties. Calibration models were developed by partial least-squares regression (PLSR) using quantitative measures of lycopene concentration from liquid chromatography as reference method. IR spectra showed a distinct marker band at 957 cm(-1) for trans Carbon-Hydrogen (CH) deformation vibration of lycopene. PLSR models predicted the lycopene content accurately and reproducibly with a correlation coefficient (sigma) of 0.96 and standard error of cross-validation <0.80 mg/100 g. ATR-IR spectroscopy allowed for rapid, simple, and accurate determination of lycopene in tomatoes with minimal sample preparation. Results suggest that the ATR-IR method is applicable for high-throughput quantitative analysis and screening for lycopene in tomatoes.

  7. Light at the interface: the potential of attenuated total reflection infrared spectroscopy for understanding heterogeneous catalysis in water.

    PubMed

    Mojet, Barbara Louise; Ebbesen, Sune Dalgaard; Lefferts, Leon

    2010-12-01

    IR spectroscopy has been an important tool for studying detailed interactions of reactants and reaction-intermediates with catalyst surfaces. Studying reactions in water is, however, far from trivial, due to the excessive absorption of infrared light by water. One way to deal with this is the use of Attenuated Total Reflection spectroscopy (ATR-IR) minimizing the path length of infrared light through the water. Moreover, ATR-IR allows for a direct comparison of reactions in gas and water on the same sample, which bridges the gap between separate catalyst investigations in gas and liquid phase. This tutorial review describes recent progress in using ATR-IR for studying heterogeneous catalysts in water. An overview is given of the important aspects to be taken into account when using ATR-IR to study heterogeneous catalysts in liquid phase, like the procedure to prepare stable catalyst layers on the internal reflection element. As a case study, CO adsorption and oxidation on noble metal catalysts is investigated with ATR-IR in gas and water. The results show a large effect of water and pH on the adsorption and oxidation of CO on Pt/Al(2)O(3) and Pd/Al(2)O(3). From the results it is concluded that water affects the metal particle potential as well as the adsorbed CO molecule directly, resulting in higher oxidation rates in water compared to gas phase. Moreover, also pH influences the metal particle potential with a clear effect on the observed oxidation rates. Finally, the future outlook illustrates that ATR-IR spectroscopy holds great promise in the field of liquid phase heterogeneous catalysis.

  8. Modeling Microalgal Biosediment Formation based on Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Monitoring.

    PubMed

    Ogburn, Zachary L; Vogt, Frank

    2017-01-01

    With increasing amounts of anthropogenic pollutants being released into ecosystems, it becomes ever more important to understand their fate and interactions with living organisms. Microalgae play an important ecological role as they are ubiquitous in marine environments and sequester inorganic pollutants which they transform into organic biomass. Of particular interest in this study is their role as a sink for atmospheric CO2, a greenhouse gas, and nitrate, one cause of harmful algal blooms. Novel chemometric hard-modeling methodologies have been developed for interpreting phytoplankton's chemical and physiological adaptations to changes in their growing environment. These methodologies will facilitate investigations of environmental impacts of anthropogenic pollutants on chemical and physiological properties of marine microalgae (here: Nannochloropsis oculata). It has been demonstrated that attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can gain insights into both and this study only focuses on the latter. From time-series of spectra, the rate of microalgal biomass settling on top of a horizontal ATR element is derived which reflects several of phytoplankton's physiological parameters such as growth rate, cell concentrations, cell size, and buoyancy. In order to assess environmental impacts on such parameters, microalgae cultures were grown under 25 different chemical scenarios covering 200-600 ppm atmospheric CO2 and 0.35-0.75 mM dissolved NO3(-). After recording time-series of ATR FT-IR spectra, a multivariate curve resolution-alternating least squares (MCR-ALS) algorithm extracted spectroscopic and time profiles from each data set. From the time profiles, it was found that in the considered concentration ranges only NO3(-) has an impact on the cells' physiological properties. In particular, the cultures' growth rate has been influenced by the ambient chemical conditions. Thus, the presented spectroscopic

  9. Analysis of H2O in silicate glass using attenuated total reflectance (ATR) micro-FTIR spectroscopy

    USGS Publications Warehouse

    Lowenstern, Jacob B.; Pitcher, Bradley W.

    2013-01-01

    We present a calibration for attenuated total reflectance (ATR) micro-FTIR for analysis of H2O in hydrous glass. A Ge ATR accessory was used to measure evanescent wave absorption by H2O within hydrous rhyolite and other standards. Absorbance at 3450 cm−1 (representing total H2O or H2Ot) and 1630 cm−1 (molecular H2O or H2Om) showed high correlation with measured H2O in the glasses as determined by transmission FTIR spectroscopy and manometry. For rhyolite, wt%H2O=245(±9)×A3450-0.22(±0.03) and wt%H2Om=235(±11)×A1630-0.20(±0.03) where A3450 and A1630 represent the ATR absorption at the relevant infrared wavelengths. The calibration permits determination of volatiles in singly polished glass samples with spot size down to ~5 μm (for H2O-rich samples) and detection limits of ~0.1 wt% H2O. Basaltic, basaltic andesite and dacitic glasses of known H2O concentrations fall along a density-adjusted calibration, indicating that ATR is relatively insensitive to glass composition, at least for calc-alkaline glasses. The following equation allows quantification of H2O in silicate glasses that range in composition from basalt to rhyolite: wt%H2O=(ω×A3450/ρ)+b where ω = 550 ± 21, b = −0.19 ± 0.03, ρ = density, in g/cm3, and A3450 is the ATR absorbance at 3450 cm−1. The ATR micro-FTIR technique is less sensitive than transmission FTIR, but requires only a singly polished sample for quantitative results, thus minimizing time for sample preparation. Compared with specular reflectance, it is more sensitive and better suited for imaging of H2O variations in heterogeneous samples such as melt inclusions. One drawback is that the technique can damage fragile samples and we therefore recommend mounting of unknowns in epoxy prior to polishing. Our calibration should hold for any Ge ATR crystals with the same incident angle (31°). Use of a different crystal type or geometry would require measurement of several H2O-bearing standards to provide a crystal

  10. Exploration of attenuated total reflectance mid-infrared spectroscopy and multivariate calibration to measure immunoglobulin G in human sera.

    PubMed

    Hou, Siyuan; Riley, Christopher B; Mitchell, Cynthia A; Shaw, R Anthony; Bryanton, Janet; Bigsby, Kathryn; McClure, J Trenton

    2015-09-01

    Immunoglobulin G (IgG) is crucial for the protection of the host from invasive pathogens. Due to its importance for human health, tools that enable the monitoring of IgG levels are highly desired. Consequently there is a need for methods to determine the IgG concentration that are simple, rapid, and inexpensive. This work explored the potential of attenuated total reflectance (ATR) infrared spectroscopy as a method to determine IgG concentrations in human serum samples. Venous blood samples were collected from adults and children, and from the umbilical cord of newborns. The serum was harvested and tested using ATR infrared spectroscopy. Partial least squares (PLS) regression provided the basis to develop the new analytical methods. Three PLS calibrations were determined: one for the combined set of the venous and umbilical cord serum samples, the second for only the umbilical cord samples, and the third for only the venous samples. The number of PLS factors was chosen by critical evaluation of Monte Carlo-based cross validation results. The predictive performance for each PLS calibration was evaluated using the Pearson correlation coefficient, scatter plot and Bland-Altman plot, and percent deviations for independent prediction sets. The repeatability was evaluated by standard deviation and relative standard deviation. The results showed that ATR infrared spectroscopy is potentially a simple, quick, and inexpensive method to measure IgG concentrations in human serum samples. The results also showed that it is possible to build a united calibration curve for the umbilical cord and the venous samples.

  11. Dynamics of layer-by-layer growth of a polyelectrolyte multilayer studied in situ using attenuated total reflectance infrared spectroscopy.

    PubMed

    Owusu-Nkwantabisah, Silas; Gammana, Madhira; Tripp, Carl P

    2014-10-07

    Attenuated total reflectance infrared spectroscopy (ATR-IR) was used to study the dynamic layer-by-layer (LBL) growth of a sodium polyacrylate (NaPA)/poly(diallydimethylammonium) chloride (PDADMAC) multilayer on TiO2 particles. Molecular weights (Mw) used were 30 and 60 kDa for NaPA and 8.5 and 150 kDa for PDADMAC. IR spectra were recorded in situ as a function of time and were used to obtain the dynamic mass adsorbed and bound fraction of the polymers during each deposition step. For 30 kDa NaPA layers, the dynamics of adsorption show an initial rapid rise in mass followed by a slow increase toward a plateau value upon LBL with 150 kDa PDADMAC. In contrast, the 60 kDa NaPA layers achieve a plateau quickly and do not show a slow increase toward a plateau. In the case of LBL with 150 kDa PDADMAC, the dynamics of the bound fraction of polymer per layer suggest that polymer diffusion and conformational rearrangement occur for the layers of 30 kDa NaPA but not for the 60 kDa NaPA layers. Furthermore, PDADMAC adsorption profiles show that there is no diffusion of the PDADMAC layers and that PDADMAC flattens onto the underlying layer. A linear growth in the mass adsorbed per layer was observed for 150 kDa PDADMAC with both molecular weights of NaPA. In the case of 8.5 kDa PDADMAC, smaller growth increments and the desorption of underlying layers were observed. This work demonstrates the use of ATR-IR in obtaining the dynamics of LBL multilayer formation. Furthermore, it provides an example in which polymer diffusion during LBL film formation does not lead to exponential growth.

  12. A quantitative study for determination of sugar concentration using attenuated total reflectance terahertz (ATR-THz) spectroscopy

    NASA Astrophysics Data System (ADS)

    Suhandy, Diding; Suzuki, Tetsuhito; Ogawa, Yuichi; Kondo, Naoshi; Ishihara, Takeshi; Takemoto, Yuichiro

    2011-06-01

    The objective of our research was to use ATR-THz spectroscopy together with chemometric for quantitative study in food analysis. Glucose, fructose and sucrose are main component of sugar both in fresh and processed fruits. The use of spectroscopic-based method for sugar determination is well reported especially using visible, near infrared (NIR) and middle infrared (MIR) spectroscopy. However, the use of terahertz spectroscopy for sugar determination in fruits has not yet been reported. In this work, a quantitative study for sugars determination using attenuated total reflectance terahertz (ATR-THz) spectroscopy was conducted. Each samples of glucose, fructose and sucrose solution with different concentrations were prepared respectively and their absorbance spectra between wavenumber 20 and 450 cm-1 (between 0.6 THz and 13.5 THz) were acquired using a terahertz-based Fourier Transform spectrometer (FARIS-1S, JASCO Co., Japan). This spectrometer was equipped with a high pressure of mercury lamp as light source and a pyroelectric sensor made from deuterated L-alanine triglycine sulfate (DLTGS) as detector. Each spectrum was acquired using 16 cm-1 of resolution and 200 scans for averaging. The spectra of water and sugar solutions were compared and discussed. The results showed that increasing sugar concentration caused decreasing absorbance. The correlation between sugar concentration and its spectra was investigated using multivariate analysis. Calibration models for glucose, fructose and sucrose determination were developed using partial least squares (PLS) regression. The calibration model was evaluated using some parameters such as coefficient of determination (R2), standard error of calibration (SEC), standard error of prediction (SEP), bias between actual and predicted sugar concentration value and ratio prediction to deviation (RPD) parameter. The cross validation method was used to validate each calibration model. It is showed that the use of ATR

  13. Fourier Transform Infrared with Attenuated Total Reflectance Applied to the Discrimination of Freshwater Planktonic Coccoid Green Microalgae

    PubMed Central

    de Moraes, Guilherme Pavan; Vieira, Armando Augusto Henriques

    2014-01-01

    Despite the recent advances on fine taxonomic discrimination in microorganisms, namely using molecular biology tools, some groups remain particularly problematic. Fine taxonomy of green algae, a widely distributed group in freshwater ecosystems, remains a challenge, especially for coccoid forms. In this paper, we propose the use of the Fourier Transform Infrared (FTIR) spectroscopy as part of a polyphasic approach to identify and classify coccoid green microalgae (mainly order Sphaeropleales), using triplicated axenic cultures. The attenuated total reflectance (ATR) technique was tested to reproducibility of IR spectra of the biological material, a primary requirement to achieve good discrimination of microalgal strains. Spectral window selection was also tested, in conjunction with the first derivative treatment of spectra, to determine which regions of the spectrum provided better separation and clustering of strains. The non-metric multidimensional scaling (NMDS), analysis of similarities (ANOSIM) and hierarchical clusters (HCA), demonstrated a correct discrimination and classification of closely related strains of chlorophycean coccoid microalgae, with respect to currently accepted classifications. FTIR-ATR was highly reproducible, and provided an excellent discrimination at the strain level. The best separation was achieved by analyzing the spectral windows of 1500–1200 cm−1 and 900–675 cm−1, which differs from those used in previously studies for the discrimination of broad algal groups, and excluding spectral regions related to storage compounds, which were found to give poor discrimination. Furthermore, hierarchical cluster analyses have positioned the strains tested into clades correctly, reproducing their taxonomic orders and families. This study demonstrates that FTIR-ATR has great potential to complement classical approaches for fine taxonomy of coccoid green microalgae, though a careful spectrum region selection is needed. PMID:25541701

  14. [Characterization of kale (Brassica oberacea var acephala) under thallium stress by in situ attenuated total reflection FTIR].

    PubMed

    Yao, Yan; Zhang, Ping; Wang, Zhen-Chun; Chen, Yong-Heng

    2009-01-01

    The experiment was designed based on consumption of carbon dioxide through the photosynthesis of Brassica oberacea var acephala leaf, and the photosynthesis of kale leaf under thallium stress was investigated by in situ attenuated total reflection FTIR (in situ ATR-FTIR). The ATR-FTIR showed that the absorption peaks of leaves had no obvious difference between plants growing in thallium stress soil and plants growing in non-thallium pollution soil, and the strong peaks at 3,380 cm(-1) could be assigned to the absorption of water, carbohydrate, protein or amide; the strong peaks at 2,916 and 2,850 cm(-1) assigned to the absorption of carbohydrate or aliphatic compound; the peaks at 1,640 cm(-1) assigned to the absorption of water. However, as detected by the in situ ATR-FTIR, the double peaks (negative peaks) at 2,360 and 2,340 cm(-1) that are assigned to the absorption of CO2 appeared and became high gradually. It was showed that kale was carrying photosynthesis. At the same time, the carbon dioxide consumption speed of leaf under thallium stress was obviously larger than that of the blank It was expressed that photosynthesis under thallium stress was stronger than the blank All these represented that kale had certain tolerance to the heavy metal thallium. Meanwhile, the carbon dioxide consumption of grown-up leaf was more than that of young leaf whether or not under thallium stress. It was also indicated that the intensity of photosynthesis in grown-up leaf is higher than that in young leaf.

  15. Attenuated total internal reflection infrared microspectroscopic imaging using a large-radius germanium internal reflection element and a linear array detector.

    PubMed

    Patterson, Brian M; Havrilla, George J

    2006-11-01

    The number of techniques and instruments available for Fourier transform infrared (FT-IR) microspectroscopic imaging has grown significantly over the past few years. Attenuated total internal reflectance (ATR) FT-IR microspectroscopy reduces sample preparation time and has simplified the analysis of many difficult samples. FT-IR imaging has become a powerful analytical tool using either a focal plane array or a linear array detector, especially when coupled with a chemometric analysis package. The field of view of the ATR-IR microspectroscopic imaging area can be greatly increased from 300 x 300 microm to 2500 x 2500 microm using a larger internal reflection element of 12.5 mm radius instead of the typical 1.5 mm radius. This gives an area increase of 70x before aberrant effects become too great. Parameters evaluated include the change in penetration depth as a function of beam displacement, measurements of the active area, magnification factor, and change in spatial resolution over the imaging area. Drawbacks such as large file size will also be discussed. This technique has been successfully applied to the FT-IR imaging of polydimethylsiloxane foam cross-sections, latent human fingerprints, and a model inorganic mixture, which demonstrates the usefulness of the method for pharmaceuticals.

  16. In Situ Focused Beam Reflectance Measurement (FBRM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and Raman Characterization of the Polymorphic Transformation of Carbamazepine.

    PubMed

    Zhao, Yingying; Bao, Ying; Wang, Jingkang; Rohani, Sohrab

    2012-02-09

    The objective of this work was to study the polymorphic transformation of carbamazepine from Form II to Form III in 1-propanol during seeded isothermal batch crystallization. First, the pure Form II and Form III were obtained and characterized. Then their solubilities and metastable zone limits were measured by in-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and focused beam reflectance measurement (FBRM). A transition temperature at about 34.2 °C was deduced suggesting the enantiotropic nature of this compound over the studied temperature range. To quantify the polymorph ratio during the transformation process, a new in-situ quantitative method was developed to measure the fraction of Form II by Raman spectroscopy. Successful tracking of the nucleation of the stable form and the transformation from Form II to Form III during isothermal crystallization was achieved by Raman spectroscopy and FBRM. The results from these three in-situ techniques, FBRM, FTIR and Raman were consistent with each other. The results showed a strong dependency on the amount of seeds added during isothermal crystallization.

  17. Kinetic modeling of dissolution and crystallization of slurries with attenuated total reflectance UV-visible absorbance and near-infrared reflectance measurements.

    PubMed

    Hsieh, Chun H; Billeter, Julien; McNally, Mary Ellen P; Hoffman, Ronald M; Gemperline, Paul J

    2013-06-04

    Slurries are often used in chemical and pharmaceutical manufacturing processes but present challenging online measurement and monitoring problems. In this paper, a novel multivariate kinetic modeling application is described that provides calibration-free estimates of time-resolved profiles of the solid and dissolved fractions of a substance in a model slurry system. The kinetic model of this system achieved data fusion of time-resolved spectroscopic measurements from two different kinds of fiber-optic probes. Attenuated total reflectance UV-vis (ATR UV-vis) and diffuse reflectance near-infrared (NIR) spectra were measured simultaneously in a small-scale semibatch reactor. A simplified comprehensive kinetic model was then fitted to the time-resolved spectroscopic data to determine the kinetics of crystallization and the kinetics of dissolution for online monitoring and quality control purposes. The parameters estimated in the model included dissolution and crystal growth rate constants, as well as the dissolution rate order. The model accurately estimated the degree of supersaturation as a function of time during conditions when crystallization took place and accurately estimated the degree of undersaturation during conditions when dissolution took place.

  18. Combined Light Microscopy and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy for Integration of Biofilm Structure, Distribution, and Chemistry at Solid-Liquid Interfaces

    PubMed Central

    Suci, P. A.; Siedlecki, K. J.; Palmer, R. J.; White, D. C.; Geesey, G. G.

    1997-01-01

    Reflected differential interference contrast microscopy and attenuated total reflection Fourier transform infrared spectroscopy were used to obtain complementary data on the structural and chemical properties of a biofilm. This information was obtained nondestructively, quasisimultaneously, and in real time, thereby permitting the verification of time-dependent relationships between the biofilm's population structure, distribution, and interfacial chemistry. The approach offers opportunities to examine these relationships on a variety of substrata in the presence of a bulk aqueous phase under controlled hydrodynamic conditions. PMID:16535743

  19. Application of the Polynomial-Based Least Squares and Total Least Squares Models for the Attenuated Total Reflection Fourier Transform Infrared Spectra of Binary Mixtures of Hydroxyl Compounds.

    PubMed

    Shan, Peng; Peng, Silong; Zhao, Yuhui; Tang, Liang

    2016-03-01

    An analysis of binary mixtures of hydroxyl compound by Attenuated Total Reflection Fourier transform infrared spectroscopy (ATR FT-IR) and classical least squares (CLS) yield large model error due to the presence of unmodeled components such as H-bonded components. To accommodate these spectral variations, polynomial-based least squares (LSP) and polynomial-based total least squares (TLSP) are proposed to capture the nonlinear absorbance-concentration relationship. LSP is based on assuming that only absorbance noise exists; while TLSP takes both absorbance noise and concentration noise into consideration. In addition, based on different solving strategy, two optimization algorithms (limited-memory Broyden-Fletcher-Goldfarb-Shanno (LBFGS) algorithm and Levenberg-Marquardt (LM) algorithm) are combined with TLSP and then two different TLSP versions (termed as TLSP-LBFGS and TLSP-LM) are formed. The optimum order of each nonlinear model is determined by cross-validation. Comparison and analyses of the four models are made from two aspects: absorbance prediction and concentration prediction. The results for water-ethanol solution and ethanol-ethyl lactate solution show that LSP, TLSP-LBFGS, and TLSP-LM can, for both absorbance prediction and concentration prediction, obtain smaller root mean square error of prediction than CLS. Additionally, they can also greatly enhance the accuracy of estimated pure component spectra. However, from the view of concentration prediction, the Wilcoxon signed rank test shows that there is no statistically significant difference between each nonlinear model and CLS.

  20. Application of laboratory and portable attenuated total reflectance infrared spectroscopic approaches for rapid quantification of alpaca serum immunoglobulin G.

    PubMed

    Elsohaby, Ibrahim; Burns, Jennifer B; Riley, Christopher B; Shaw, R Anthony; McClure, J Trenton

    2017-01-01

    The objective of this study was to develop and compare the performance of laboratory grade and portable attenuated total reflectance infrared (ATR-IR) spectroscopic approaches in combination with partial least squares regression (PLSR) for the rapid quantification of alpaca serum IgG concentration, and the identification of low IgG (<1000 mg/dL), which is consistent with the diagnosis of failure of transfer of passive immunity (FTPI) in neonates. Serum samples (n = 175) collected from privately owned, healthy alpacas were tested by the reference method of radial immunodiffusion (RID) assay, and laboratory grade and portable ATR-IR spectrometers. Various pre-processing strategies were applied to the ATR-IR spectra that were linked to corresponding RID-IgG concentrations, and then randomly split into two sets: calibration (training) and test sets. PLSR was applied to the calibration set and calibration models were developed, and the test set was used to assess the accuracy of the analytical method. For the test set, the Pearson correlation coefficients between the IgG measured by RID and predicted by both laboratory grade and portable ATR-IR spectrometers was 0.91. The average differences between reference serum IgG concentrations and the two IR-based methods were 120.5 mg/dL and 71 mg/dL for the laboratory and portable ATR-IR-based assays, respectively. Adopting an IgG concentration <1000 mg/dL as the cut-point for FTPI cases, the sensitivity, specificity, and accuracy for identifying serum samples below this cut point by laboratory ATR-IR assay were 86, 100 and 98%, respectively (within the entire data set). Corresponding values for the portable ATR-IR assay were 95, 99 and 99%, respectively. These results suggest that the two different ATR-IR assays performed similarly for rapid qualitative evaluation of alpaca serum IgG and for diagnosis of IgG <1000 mg/dL, the portable ATR-IR spectrometer performed slightly better, and provides more flexibility for potential

  1. Application of laboratory and portable attenuated total reflectance infrared spectroscopic approaches for rapid quantification of alpaca serum immunoglobulin G

    PubMed Central

    Burns, Jennifer B.; Riley, Christopher B.; Shaw, R. Anthony; McClure, J. Trenton

    2017-01-01

    The objective of this study was to develop and compare the performance of laboratory grade and portable attenuated total reflectance infrared (ATR-IR) spectroscopic approaches in combination with partial least squares regression (PLSR) for the rapid quantification of alpaca serum IgG concentration, and the identification of low IgG (<1000 mg/dL), which is consistent with the diagnosis of failure of transfer of passive immunity (FTPI) in neonates. Serum samples (n = 175) collected from privately owned, healthy alpacas were tested by the reference method of radial immunodiffusion (RID) assay, and laboratory grade and portable ATR-IR spectrometers. Various pre-processing strategies were applied to the ATR-IR spectra that were linked to corresponding RID-IgG concentrations, and then randomly split into two sets: calibration (training) and test sets. PLSR was applied to the calibration set and calibration models were developed, and the test set was used to assess the accuracy of the analytical method. For the test set, the Pearson correlation coefficients between the IgG measured by RID and predicted by both laboratory grade and portable ATR-IR spectrometers was 0.91. The average differences between reference serum IgG concentrations and the two IR-based methods were 120.5 mg/dL and 71 mg/dL for the laboratory and portable ATR-IR-based assays, respectively. Adopting an IgG concentration <1000 mg/dL as the cut-point for FTPI cases, the sensitivity, specificity, and accuracy for identifying serum samples below this cut point by laboratory ATR-IR assay were 86, 100 and 98%, respectively (within the entire data set). Corresponding values for the portable ATR-IR assay were 95, 99 and 99%, respectively. These results suggest that the two different ATR-IR assays performed similarly for rapid qualitative evaluation of alpaca serum IgG and for diagnosis of IgG <1000 mg/dL, the portable ATR-IR spectrometer performed slightly better, and provides more flexibility for potential

  2. Single-pass attenuated total reflection Fourier transform infrared spectroscopy for the prediction of protein secondary structure.

    PubMed

    Smith, Brandye M; Oswald, Lisa; Franzen, Stefan

    2002-07-15

    Principal component regression (PCR) was applied to a spectral library of proteins in H2O solution acquired by single-pass attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy. PCR was used to predict the secondary structure content, principally alpha-helical and the beta-sheet content, of proteins within a spectral library. Quantitation of protein secondary structure content was performed as a proof of principle that use of single-pass ATR-FT-IR is an appropriate method for protein secondary structure analysis. The ATR-FT-IR method permits acquisition of the entire spectral range from 700 to 3900 cm(-1) without significant interference from water bands. An "inside model space" bootstrap and a genetic algorithm (GA) were used to improve prediction results. Specifically, the bootstrap was utilized to increase the number of replicates for adequate training and validation of the PCR model. The GA was used to optimize PCR parameters, particularly wavenumber selection. The use of the bootstrap allowed for adequate representation of variability in the amide A, amide B, and C-H stretching regions due to differing levels of sample hydration. Implementation of the bootstrap improved the robustness of the PCR models significantly; however, the use of a GA only slightly improved prediction results. Two spectral libraries are presented where one was better suited for beta-sheet content prediction and the other for alpha-helix content prediction. The GA-optimized PCR method for alpha-helix content prediction utilized 120 wavenumbers within the amide I, II, A, B, and IV and the C-H stretching regions and 18 factors. For beta-sheet content predictions, 580 wavenumbers within the amide I, II, A, and B and the C-H stretching regions and 18 factors were used. The validation results using these two methods yielded an average absolute error of 1.7% for alpha-helix content prediction and an average absolute error of 2.3% for beta-sheet content prediction

  3. Electronic transitions in liquid amides studied by using attenuated total reflection far-ultraviolet spectroscopy and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Morisawa, Yusuke; Yasunaga, Manaka; Fukuda, Ryoichi; Ehara, Masahiro; Ozaki, Yukihiro

    2013-10-01

    Attenuated total reflection far-ultraviolet (ATR-FUV) spectra in the 140-260 nm region were measured for several types of liquid amides (formamide, FA; N-methylformamide, NMF; N-methylacetamide, NMA; N,N-dimethylformamide, NdMF; and N,N-dimethylacetamide, NdMA) to investigate their electronic transitions in the FUV region. The spectra were compared with the corresponding gas-phase spectra to examine the shift in the major absorption band in the 180-200 nm region going from the gas phase to the liquid phase, and it was found that the peak shift was dependent on the particular amide. FA and NMF, which exhibit intermolecular C=O…H-N hydrogen bonding, show a large shift of ˜0.60 eV to lower energy; however, NMA, which also exhibits hydrogen bonding, shows only a small shift. In NdMF and NdMA, C=O groups seem to be coupled, which results in a small peak shift. Two types of quantum chemical calculations, time-dependent density functional theory (TD-DFT) and symmetry-adapted-cluster configuration interaction (SAC-CI) method, were performed to elucidate the origin of the shifts and the band assignments. The shift estimated by the monomer and dimer models with TD-DFT reproduced well the observed shift from the gas phase to the liquid phase. This suggests that the intermolecular hydrogen-bonding interaction significantly affects the magnitude of the shift. The many-body effects were also considered using the larger cluster models (trimer to pentamer). The energy shift calculated using SAC-CI with the monomer and the state-specific polarizable continuum model was also accurate, indicating that the nonlinear polarization effect appears to be important. As for the band assignments, it was found that though the major band can be mainly attributed to the π-π* transition, several types of Rydberg transitions also exist in its vicinity and mixing of orbitals with the same symmetry occurs. The number and type of Rydberg transitions in the spectra depend upon the type of amide

  4. Hygrothermal degradation of (3-glycidoxypropyl)trimethoxysilane films studied by neutron and X-ray reflectivity and attenuated total reflection infrared spectroscopy.

    PubMed

    Yim, H; Kent, M S; Tallant, D R; Garcia, M J; Majewski, J

    2005-05-10

    Thin films of organosilanes have great technological importance in the areas of adhesion promotion, durability, and corrosion resistance. However, it is well-known that water can degrade organosilane films, particularly at elevated temperatures. In this work, X-ray and neutron reflectivity (XR and NR) were combined with attenuated total reflection infrared (ATR-IR) spectroscopy to study the chemical and structural changes within thin films of (3-glycidoxypropyl)trimethoxysilane (GPS) after exposure for various periods of time to air saturated with either D2O or H2O at 80 degrees C. For NR and XR, ultrathin (approximately 100 A) films were prepared by spin-coating. Both D2O and H2O provide neutron scattering contrast with GPS. Variations in the neutron scattering length density (SLD) profiles (a function of mass density and atomic composition) with conditioning time were measured after drying the samples out and also swelled with H2O or D2O vapor at room temperature. For samples that were dried out prior to measurement, little or no change was observed for H2O conditioning up to 3.5 days, but large changes were observed after 30 days of conditioning. The range of conditioning time for this structural change was narrowed to between 4 and 10 days with XR. The SLD profiles indicated that the top portion of the GPS film was transformed into a thick low-density layer after conditioning, but the bottom portion showed little structural change. A previous NR study of as-prepared GPS films involving swelling with deuterated nitrobenzene showed that the central portion of the film has much lower cross-link density than the region nearest the substrate. The present data show that the central portion also swells to a much greater extent with water and hydrolyzes more rapidly. The chemical degradation mechanism was identified by IR as hydrolysis of siloxane bonds. For ATR-IR, GPS films were prepared by dip-coating, which resulted in a greater and more variable thickness than for

  5. Use of total internal reflection Raman (TIR) and attenuated total reflection infrared (ATR-IR) spectroscopy to analyze component separation in thin offset ink films after setting on coated paper surfaces.

    PubMed

    Kivioja, Antti; Hartus, Timo; Vuorinen, Tapani; Gane, Patrick; Jääskeläinen, Anna-Stiina

    2013-06-01

    The interactive behavior of ink constituents with porous substrates during and after the offset print process has an important effect on the quality of printed products. To help elucidate the distribution of ink components between the retained ink layer and the substrate, a variety of spectroscopic and microscopic analysis techniques have been developed. This paper describes for the first time the use of total internal reflection (TIR) Raman spectroscopy to analyze the penetration behavior of separated offset ink components (linseed oil, solid color pigment) in coated papers providing chemically intrinsic information rapidly, nondestructively, and with minimal sample preparation. In addition, the already widely applied technique of attenuated total reflection infrared spectroscopy (ATR-IR) was evaluated in parallel and compared. The results of the ATR-IR Raman clearly revealed an improvement in uppermost depth resolution compared with values previously published from other nondestructive techniques, and the method is shown to be capable of providing new knowledge of the setting of thin (0.25-2 μm) offset ink films, allowing the spreading and the penetration behavior on physically different paper coating surfaces to be studied.

  6. Amplified total internal reflection.

    PubMed

    Fan, J; Dogariu, A; Wang, L J

    2003-02-24

    Totally internal reflected beams can be amplified if the lowerindex medium has gain. We analyze the reflection and refraction of light, and analytically derive the expression for the Goos-Hänchen shifts of a Gaussian beam incident on a lower-index medium, both active and absorptive. We examine the energy flow and the Goos-Hänchen shifts for various cases. The analytical results are consistent with the numerical results. For the TE mode, the Goos-Hänchen shift for the transmitted beam is exactly half of that of the reflected beam, resulting in a "1/2" rule.

  7. Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) for Rapid Determination of Microbial Cell Lipid Content: Correlation with Gas Chromatography-Mass Spectrometry (GC-MS).

    PubMed

    Millan-Oropeza, Aaron; Rebois, Rolando; David, Michelle; Moussa, Fathi; Dazzi, Alexandre; Bleton, Jean; Virolle, Marie-Joelle; Deniset-Besseau, Ariane

    2017-10-01

    There is a growing interest worldwide for the production of renewable oil without mobilizing agriculture lands; fast and reliable methods are needed to identify highly oleaginous microorganisms of potential industrial interest. The aim of this study was to demonstrate the relevance of attenuated total reflection (ATR) spectroscopy to achieve this goal. To do so, the total lipid content of lyophilized samples of five Streptomyces strains with varying lipid content was assessed with two classical quantitative but time-consuming methods, gas chromatography-mass spectrometry (GC-MS) and ATR Fourier transform infrared (ATR FT-IR) spectroscopy in transmission mode with KBr pellets and the fast ATR method, often questioned for its lack of reliability. A linear correlation between these three methods was demonstrated allowing the establishment of equations to convert ATR values expressed as CO/amide I ratio, into micrograms of lipid per milligram of biomass. The ATR method proved to be as reliable and quantitative as the classical GC-MS and FT-IR in transmission mode methods but faster and more reproducible than the latter since it involves far less manipulation for sample preparation than the two others. Attenuated total reflection could be regarded as an efficient fast screening method to identify natural or genetically modified oleaginous microorganisms by the scientific community working in the field of bio-lipids.

  8. Development of an Attenuated Total Reflection Based Fiber-Optic Sensor for Real-time Sensing of Biofilm Formation.

    PubMed

    Orii, Tatsuya; Okazaki, Takuya; Hata, Noriko; Sugawara, Kazuharu; Rahman, Faidz A; Kuramitz, Hideki

    2017-01-01

    A fiber-optic sensor capable of real-time monitoring of biofilm formation in water was developed. The sensor can be easily fabricated by removing the cladding of a multimode fiber optic to expose the core. The sensing action is based on the penetration of an evanescent wave through a biofilm formed on the surface of the exposed fiber core during total internal reflection. The proposed setup can be used to analyze the transmittance response over a wide wavelength range using a white-light source and a spectroscopy detector. The change in transmittance with respect to the biofilm formation on the fiber core surface was observed. The findings from this study showed that the sensor detection had better sensitivity at near-infrared wavelengths than at visible-light wavelengths. Moreover, the sensitivity of this sensor could be controlled by surface modifications of the core surface through electrostatic interactions, involving a silane coupling layer, polyanions, and polycations. The developed sensor was successfully applied to evaluating of the effectiveness of a commercial biofilm inhibitor.

  9. Investigation of binary and ternary systems of ionic liquids with water and/or supercritical CO2 by in situ attenuated total reflection infrared spectroscopy.

    PubMed

    Andanson, Jean-Michel; Jutz, Fabian; Baiker, Alfons

    2010-02-18

    Two commonly used ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]), as well as binary and ternary mixtures of them with water and/or supercritical CO(2) (scCO(2)) were investigated by means of infrared spectroscopy at high pressure. The experiments were performed using attenuated total reflection (ATR) infrared spectroscopy on dry and wet ILs at 40 degrees C and pressures up to 150 bar of scCO(2). The studies indicate that the content of water does not change significantly the solubility of CO(2) in the ionic liquids tested. Furthermore, the presence of water does not change significantly the interaction between the IL anion and CO(2), which explains why the presence of water in IL does not modify the solubility of CO(2) in the system, even in the case of an initial molar ratio of approximately 50/50 of water in [bmim][BF(4)]. We show that despite the limited solubility of water in supercritical CO(2) an ionic liquid can be efficiently dried using scCO(2) extraction even in the case of a hydrophilic ionic liquid (e.g., [bmim][BF(4)]). During the scCO(2) extraction, the concentration of water was followed in situ using attenuated total reflection (ATR) infrared spectroscopy. After extraction, no residual water could be detected by this technique, which corresponds approximately to a water concentration of below 320 ppm.

  10. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) Applied to Study the Distribution of Ink Components in Printed Newspapers.

    PubMed

    Gómez, Nuria; Molleda, Cristina; Quintana, Ester; Carbajo, José M; Rodríguez, Alejandro; Villar, Juan C

    2016-09-01

    A new method was developed to study how the oil and cyan pigments of cold-set ink are distributed in newspaper thickness. The methodology involved laboratory printing followed by delamination of the printed paper. The unprinted side, printed side, and resulting layers were analyzed using attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR). Three commercial newspapers and black and cyan cold-set inks were chosen for the study. Attenuated total reflection Fourier transform infrared spectroscopy enabled the proportion of oil and cyan pigment on the printed surface and throughout the sheet thickness to be measured. Oil percentage was evaluated as the area increment of the region from 2800 cm(-1) to 3000 cm(-1) The relative amount of cyan pigment was determined as the area of the absorption band at 730 cm(-1) The ink oil was found mainly below half the paper thickness, whereas the pigment was detected at the layers closer to the printed surface, at a depth penetration of less than 15 µm (20% of thickness). Distribution of these two components in paper thickness depended on the type of cold-set ink, the amount of ink transferred, and the newspaper properties. © The Author(s) 2016.

  11. Rapid determination of free fatty acid content in waste deodorizer distillates using single bounce-attenuated total reflectance-FTIR spectroscopy.

    PubMed

    Naz, Saba; Sherazi, Sayed Tufail Hussain; Talpur, Farah N; Mahesar, Sarfaraz A; Kara, Huseyin

    2012-01-01

    A simple, rapid, economical, and environmentally friendly analytical method was developed for the quantitative assessment of free fatty acids (FFAs) present in deodorizer distillates and crude oils by single bounce-attenuated total reflectance-FTIR spectroscopy. Partial least squares was applied for the calibration model based on the peak region of the carbonyl group (C=O) from 1726 to 1664 cm(-1) associated with the FFAs. The proposed method totally avoided the use of organic solvents or costly standards and could be applied easily in the oil processing industry. The accuracy of the method was checked by comparison to a conventional standard American Oil Chemists' Society (AOCS) titrimetric procedure, which provided good correlation (R = 0.99980), with an SD of +/- 0.05%. Therefore, the proposed method could be used as an alternate to the AOCS titrimetric method for the quantitative determination of FFAs especially in deodorizer distillates.

  12. Quantitative determination of Malathion in pesticide by modified attenuated total reflectance-Fourier transform infrared spectrometry applying genetic algorithm wavelength selection method.

    PubMed

    Khanmohammadi, M; Karimi, M A; Ghasemi, K; Jabbari, M; Garmarudi, A Bagheri

    2007-04-30

    A simple and environment friendly method was developed for determination of Malathion content of analytical and commercial insecticide samples with no special preparation. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra were characterized and 1000-2000cm(-1) region was selected for quantitative analysis utilizing partial least square (PLS) and two wavelength selection methods: (a) principal component regression (PCR) and (b) genetic algorithm (GA). Relative error of prediction (REP) was calculated in PLS, PCR-PLS and GA-PLS methods and was 3.536, 1.656 and 0.188, respectively. Proposed method is successfully applicable for quantification of Malathion in commercial grade samples and reliable results in comparison with known methods, confirms this idea.

  13. Textured and smooth breast implants: is there a difference in the chemical structure of silicone?: an analysis with fourier transformation infrared and attenuated total reflectance spectroscopy.

    PubMed

    Persichetti, Paolo; Tenna, Stefania; Delfino, Sergio; Abbruzzese, Franca; Trombetta, Marcella; Scuderi, Nicolò

    2009-10-01

    Scientific controversy concerning silicone and its biocompatibility has been ongoing for the last 10 years. This study on textured and smooth silicone breast implant shells using fourier transformation infrared spectroscopy associated with attenuated total reflectance cells aimed to identify eventual chemical modifications of silicone induced by texturization. The surfaces of 8 new implants produced by 2 well-known manufactures have been taken into consideration. A sample 1 cm2 has been harvested from the anterior and posterior sides of textured and smooth shells. Infrared spectra were then recorded, evaluated, and compared with the reference spectrum of pure silicone. Potentially reactive groups, known as silanols, were identified, in all shells, intensity increasing in textured implants (P < 0.05), whereas no silanols were detected in the spectrum of pure silicone. These results suggest that polar groups, present in manipulated silicone might influence capsula formation.

  14. New tool for epidermal and cosmetic formulation studies by attenuated total-reflection spectroscopy using a flexible mid-infrared fiber probe.

    PubMed

    Heise, H M; Küpper, L; Pittermann, W; Butvina, L N

    2001-11-01

    The potential of mid-infrared attenuated total-reflection spectroscopy for dermatology studies has been increased by the development of a flexible fiber-optic probe from silver halide material. Such a tool significantly eases epidermal surface characterization. Spectra of human forearm skin and of bovine udder skin (BUS-model), which is used as a substitute for in-vivo tests on man, were compared, and as an example low concentrations of vitamin E acetate (alpha-tocopherol acetate) in the stratum corneum were measured after topical skin application. Depth profiling was enabled by repeated steps of tape stripping and subsequent skin measurement. The infrared methodology is rapid and can be applied to small areas of skin. It is also sufficiently sensitive for analysis of a large variety of cosmetic formulations and dermatopharmaca. Discrimination of vehicle formulations is possible because of the large information content of mid-infrared spectra.

  15. Classification of pumpkin seed oils according to their species and genetic variety by attenuated total reflection Fourier-transform infrared spectroscopy.

    PubMed

    Saucedo-Hernández, Yanelis; Lerma-García, María Jesús; Herrero-Martínez, José Manuel; Ramis-Ramos, Guillermo; Jorge-Rodríguez, Elisa; Simí-Alfonso, Ernesto F

    2011-04-27

    Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), followed by multivariate treatment of the spectral data, was used to classify seed oils of the genus Cucurbita (pumpkins) according to their species as C. maxima, C. pepo, and C. moschata. Also, C. moschata seed oils were classified according to their genetic variety as RG, Inivit C-88, and Inivit C-2000. Up to 23 wavelength regions were selected on the spectra, each region corresponding to a peak or shoulder. The normalized absorbance peak areas within these regions were used as predictors. Using linear discriminant analysis (LDA), an excellent resolution among all categories concerning both Cucurbita species and C. moschata varieties was achieved. The proposed method was straightforward and quick and can be easily implemented. Quality control of pumpkin seed oils is important because Cucurbita species and genetic variety are both related to the pharmaceutical properties of the oils.

  16. Application of micro-attenuated total reflectance Fourier transform infrared spectroscopy to ink examination in signatures written with ballpoint pen on questioned documents.

    PubMed

    Nam, Yun Sik; Park, Jin Sook; Lee, Yeonhee; Lee, Kang-Bong

    2014-05-01

    Questioned documents examined in a forensic laboratory sometimes contain signatures written with ballpoint pen inks; these signatures were examined to assess the feasibility of micro-attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy as a forensic tool. Micro-ATR FTIR spectra for signatures written with 63 ballpoint pens available commercially in Korea were obtained and used to construct an FTIR spectral database. A library-searching program was utilized to identify the manufacturer, blend, and model of each black ballpoint pen ink based upon their FTIR peak intensities, positions, and patterns in the spectral database. This FTIR technique was also successfully used in determining the sequence of homogeneous line intersections from the crossing lines of two ballpoint pen signatures. We have demonstrated with a set of sample documents that micro-ATR FTIR is a viable nondestructive analytical method that can be used to identify the origin of the ballpoint pen ink used to mark signatures.

  17. Epidermal in vivo and in vitro studies by attenuated total reflection mid-infrared spectroscopy using flexible silver halide fibre-probes

    NASA Astrophysics Data System (ADS)

    Heise, H. M.; Küpper, L.; Pittermann, W.; Stücker, M.

    2003-06-01

    Dermatology studies focussing on the stratum corneum were carried out by infrared attenuated total reflection (ATR) spectroscopy using flexible fibre-optic probes made from square cross-section polycrystalline silver halide material. We compared the upper horny layer of human and bovine udder skin (BUS). As a substitute for human in vivo tests, the in vitro model of the isolated perfused bovine udder skin (BUS-model) has been used. For depth profiling of endogenous and topically applied compounds, subsequent stripping of corneocyte layers by adhesive tape application was carried out in combination with in situ fibre-probe ATR-measurements. The non-invasive measurement technique was also applied to patients with various skin abnormalities. Owing to the remote sensing capability, the technique presented is promising, since it opens the field for new medical and cosmetic applications, which are otherwise not possible with conventional sampling compartment based ATR-accessories.

  18. Origin identification of dried distillers grains with solubles using attenuated total reflection Fourier transform mid-infrared spectroscopy after in situ oil extraction.

    PubMed

    Vermeulen, Ph; Fernández Pierna, J A; Abbas, O; Dardenne, P; Baeten, V

    2015-12-15

    The ban on using processed animal proteins in feedstuffs led the feed sector to look for other sources of protein. Dried distillers grains with solubles (DDGS) could be considered as an important source in this regard. They are imported into Europe mainly for livestock feed. Identifying their origin is essential when labelling is missing and for feed safety, particularly in a crisis situation resulting from contamination. This study investigated applying attenuated total reflection Fourier transform mid-infrared spectroscopy (ATR-FT-MIR) to the oil fraction extracted from samples in situ in order to identify the origin of DDGS. The use of spectroscopic and chemometric tools enabled the botanical and geographical origins of DDGS, as well as the industrial process used to produce them, to be identified. The models developed during the study provided a classification higher than 95% using an external validation set.

  19. An attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopic study of gas adsorption on colloidal stearate-capped ZnO catalyst substrate.

    PubMed

    Silverwood, Ian P; Keyworth, Colin W; Brown, Neil J; Shaffer, Milo S P; Williams, Charlotte K; Hellgardt, Klaus; Kelsall, Geoff H; Kazarian, Sergei G

    2014-01-01

    Attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy has been applied in situ to study gas adsorption on a colloidal stearate-capped zinc oxide (ZnO) surface. Infrared spectra of a colloidal stearate-capped ZnO catalyst substrate were assigned at room temperature using zinc stearate as a reference compound. Heating was shown to create a monodentate species that allowed conformational change to occur, leading to altered binding geometry of the stearate ligands upon cooling. CO2 and H2 adsorption measurements demonstrated that the ligand shell was permeable and did not cover the entire surface, allowing adsorption and reaction with at least some portion of the ZnO surface. It has been demonstrated that stearate ligands did not prevent the usual chemisorption processes involved in catalytic reactions on a model ZnO catalyst system, yet the ligand-support system is dynamic under representative reaction conditions.

  20. T dependence of vibrational dynamics of water in ion-exchanged zeolites A: a detailed Fourier transform infrared attenuated total reflection study.

    PubMed

    Crupi, Vincenza; Longo, Francesca; Majolino, Domenico; Venuti, Valentina

    2005-10-15

    In order to explore the influence of cation substitution on the vibrational dynamics of water molecules in zeolites, the evolution of structural properties of the O-H stretching band of water in fully hydrated Na-A and Mg-exchanged A zeolites has been studied, for different percentages of induced ion exchange, by Fourier transform infrared attenuated total reflection spectroscopy as a function of temperature. The differences revealed in the O-H stretching band shapes have been accounted by fitting the spectra as a sum of four components, corresponding to water molecules exhibiting different types of hydrogen bonding. The dependencies of the relative intensities, peak wave numbers, and bandwidths of the resolved components on temperature and Mg2+ content have been discussed. Evidence of the "structure-maker" role played by a zeolitic surface on physisorbed water, systematically enhanced by increasing the percentage of induced ion exchange, is given in the whole explored temperature range.

  1. Potential and limitation of mid-infrared attenuated total reflectance spectroscopy for real time analysis of raw milk in milking lines.

    PubMed

    Linker, Raphael; Etzion, Yael

    2009-02-01

    Real-time information about milk composition would be very useful for managing the milking process. Mid-infrared spectroscopy, which relies on fundamental modes of molecular vibrations, is routinely used for off-line analysis of milk and the purpose of the present study was to investigate the potential of attenuated total reflectance mid-infrared spectroscopy for real-time analysis of milk in milking lines. The study was conducted with 189 samples from over 70 cows that were collected during an 18 months period. Principal component analysis, wavelets and neural networks were used to develop various models for predicting protein and fat concentration. Although reasonable protein models were obtained for some seasonal sub-datasets (determination errors attenuated total reflectance spectroscopy for in-line milk analysis is indeed quite limited.

  2. Modification of xylan in alkaline treated bleached hardwood kraft pulps as classified by attenuated total-internal-reflection (ATR) FTIR spectroscopy.

    PubMed

    Chen, Zhiwen; Hu, Thomas Q; Jang, Ho Fan; Grant, Edward

    2015-08-20

    The glucuronoxylan composition of a pulp affects the bonding between cellulosic fibres, and thus correlates with such network properties as tensile strength. Here, we demonstrate the promise of attenuated total-internal-reflection (ATR) FTIR spectroscopy as a rapid means for classifying the xylan contained in commercial bleached kraft pulps. This study draws upon samples composed of bleached eucalyptus kraft pulps and combinations of eucalyptus with other commercial bleached kraft pulps. We subject these pulp samples to systematic extraction by sodium hydroxide solutions with concentrations ranging from 0.5% to 6% to build a standard sample library with varying xylan content, quantified by acid hydrolysis, HPLC carbohydrate separation and titration. This pulp chemistry of mild alkaline extraction removes up to two-thirds of the xylan. In the NaOH concentration regime of 0.5-4%, the infrared spectral variance reflects the decrease in hemicellulose concentration as well as the cellulose crystallinity. A residual xylan component remains resistant to base solutions of higher concentrations. Principal component analysis of infrared spectra distinguishes this residual xylan as structurally variant. Both partial least squares multivariate analysis and univariate analysis confined to a feature at 964 cm(-1) in normalized second derivative IR spectra show a very good correlation with xylan content quantified by HPLC. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Measurement of conjugated linoleic acid (CLA) in CLA-rich soy oil by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR).

    PubMed

    Kadamne, Jeta V; Jain, Vishal P; Saleh, Mohammed; Proctor, Andrew

    2009-11-25

    Conjugated linoleic acid (CLA) isomers in oils are currently measured as fatty acid methyl esters by a gas chromatography-flame ionization detector (GC-FID) technique, which requires approximately 2 h to complete the analysis. Hence, we aim to develop a method to rapidly determine CLA isomers in CLA-rich soy oil. Soy oil with 0.38-25.11% total CLA was obtained by photo-isomerization of 96 soy oil samples for 24 h. A sample was withdrawn at 30 min intervals with repeated processing using a second batch of oil. Six replicates of GC-FID fatty acid analysis were conducted for each oil sample. The oil samples were scanned using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and the spectrum was collected. Calibration models were developed using partial least-squares (PLS-1) regression using Unscrambler software. Models were validated using a full cross-validation technique and tested using samples that were not included in the calibration sample set. Measured and predicted total CLA, trans,trans CLA isomers, total mono trans CLA isomers, trans-10,cis-12 CLA, trans-9,cis-11 CLA and cis-10,trans-12 CLA, and cis-9,trans-11 CLA had cross-validated coefficients of determinations (R2v) of 0.97, 0.98, 0.97, 0.98, 0.97, and 0.99 and corresponding root-mean-square error of validation (RMSEV) of 1.14, 0.69, 0.27, 0.07, 0.14, and 0.07% CLA, respectively. The ATR-FTIR technique is a rapid and less expensive method for determining CLA isomers in linoleic acid photo-isomerized soy oil than GC-FID.

  4. Attenuated Total Reflectance Fourier transform infrared spectroscopy for determination of Long Chain Free Fatty Acid concentration in oily wastewater using the double wavenumber extrapolation technique.

    PubMed

    Hao, Zisu; Malyala, Divya; Dean, Lisa; Ducoste, Joel

    2017-04-01

    Long Chain Free Fatty Acids (LCFFAs) from the hydrolysis of fat, oil and grease (FOG) are major components in the formation of insoluble saponified solids known as FOG deposits that accumulate in sewer pipes and lead to sanitary sewer overflows (SSOs). A Double Wavenumber Extrapolative Technique (DWET) was developed to simultaneously measure LCFFAs and FOG concentrations in oily wastewater suspensions. This method is based on the analysis of the Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectrum, in which the absorbance of carboxyl bond (1710cm(-1)) and triglyceride bond (1745cm(-1)) were selected as the characteristic wavenumbers for total LCFFAs and FOG, respectively. A series of experiments using pure organic samples (Oleic acid/Palmitic acid in Canola oil) were performed that showed a linear relationship between the absorption at these two wavenumbers and the total LCFFA. In addition, the DWET method was validated using GC analyses, which displayed a high degree of agreement between the two methods for simulated oily wastewater suspensions (1-35% Oleic acid in Canola oil/Peanut oil). The average determination error of the DWET approach was ~5% when the LCFFA fraction was above 10wt%, indicating that the DWET could be applied as an experimental method for the determination of both LCFFAs and FOG concentrations in oily wastewater suspensions. Potential applications of this DWET approach includes: (1) monitoring the LCFFAs and FOG concentrations in grease interceptor (GI) effluents for regulatory compliance; (2) evaluating alternative LCFFAs/FOG removal technologies; and (3) quantifying potential FOG deposit high accumulation zones in the sewer collection system.

  5. Sensing cocaine in saliva with attenuated total reflection infrared (ATR-IR) spectroscopy combined with a one-step extraction method

    NASA Astrophysics Data System (ADS)

    Hans, Kerstin M.-C.; Gianella, Michele; Sigrist, Markus W.

    2012-03-01

    On-site drug tests have gained importance, e.g., for protecting the society from impaired drivers. Since today's drug tests are majorly only positive/negative, there is a great need for a reliable, portable and preferentially quantitative drug test. In the project IrSens we aim to bridge this gap with the development of an optical sensor platform based on infrared spectroscopy and focus on cocaine detection in saliva. We combine a one-step extraction method, a sample drying technique and infrared attenuated total reflection (ATR) spectroscopy. As a first step we have developed an extraction technique that allows us to extract cocaine from saliva to an almost infrared-transparent solvent and to record ATR spectra with a commercially available Fourier Transform-infrared spectrometer. To the best of our knowledge this is the first time that such a simple and easy-to-use one-step extraction method is used to transfer cocaine from saliva into an organic solvent and detect it quantitatively. With this new method we are able to reach a current limit of detection around 10 μg/ml. This new extraction method could also be applied to waste water monitoring and controlling caffeine content in beverages.

  6. Selecting the optimum number of partial least squares components for the calibration of attenuated total reflectance-mid-infrared spectra of undesigned kerosene samples.

    PubMed

    Gómez-Carracedo, M P; Andrade, J M; Rutledge, D N; Faber, N M

    2007-03-07

    Selecting the correct dimensionality is critical for obtaining partial least squares (PLS) regression models with good predictive ability. Although calibration and validation sets are best established using experimental designs, industrial laboratories cannot afford such an approach. Typically, samples are collected in an (formally) undesigned way, spread over time and their measurements are included in routine measurement processes. This makes it hard to evaluate PLS model dimensionality. In this paper, classical criteria (leave-one-out cross-validation and adjusted Wold's criterion) are compared to recently proposed alternatives (smoothed PLS-PoLiSh and a randomization test) to seek out the optimum dimensionality of PLS models. Kerosene (jet fuel) samples were measured by attenuated total reflectance-mid-IR spectrometry and their spectra where used to predict eight important properties determined using reference methods that are time-consuming and prone to analytical errors. The alternative methods were shown to give reliable dimensionality predictions when compared to external validation. By contrast, the simpler methods seemed to be largely affected by the largest changes in the modeling capabilities of the first components.

  7. A method to quantify organic functional groups and inorganic compounds in ambient aerosols using attenuated total reflectance FTIR spectroscopy and multivariate chemometric techniques

    NASA Astrophysics Data System (ADS)

    Coury, Charity; Dillner, Ann M.

    An attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic technique and a multivariate calibration method were developed to quantify ambient aerosol organic functional groups and inorganic compounds. These methods were applied to size-resolved particulate matter samples collected in winter and summer of 2004 at three sites: a downtown Phoenix, Arizona location, a rural site near Phoenix, and an urban fringe site between the urban and rural site. Ten organic compound classes, including four classes which contain a carbonyl functional group, and three inorganic species were identified in the ambient samples. A partial least squares calibration was developed and applied to the ambient spectra, and 13 functional groups related to organic compounds (aliphatic and aromatic CH, methylene, methyl, alkene, aldehydes/ketones, carboxylic acids, esters/lactones, acid anhydrides, carbohydrate hydroxyl and ethers, amino acids, and amines) as well as ammonium sulfate and ammonium nitrate were quantified. Comparison of the sum of the mass measured by the ATR-FTIR technique and gravimetric mass indicates that this method can quantify nearly all of the aerosol mass on sub-micrometer size-segregated samples. Analysis of sample results shows that differences in organic functional group and inorganic compound concentrations at the three sampling sites can be measured with these methods. Future work will analyze the quantified data from these three sites in detail.

  8. Characterization of Developmental Immature Fiber ( im) Mutant and Texas Marker-1 (TM-1) Cotton Fibers Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy.

    PubMed

    Liu, Yongliang; Kim, Hee-Jin

    2017-01-01

    The immature fiber ( im) mutant is one type of cotton fiber mutant with unique characteristics of non-fluffy cotton bolls. Compared to its near-isogenic wild type Texas Marker-1 (TM-1), im fiber has a thin secondary cell wall and is less mature. In this work, we applied the previously proposed principal component analysis (PCA) and simple algorithms to analyze the attenuated total reflection Fourier transform infrared (ATR FT-IR) spectra of developmental im and TM-1 fibers. The results from these approaches could not effectively and consistently indicate the inherent difference between TM-1 and im fibers at the same developmental stage. The difference between TM-1 and corresponding im fibers was detected when comparing the normalized intensity variations of the 730 cm(-1) bands. The 730 cm(-1) band intensities in developmental im fibers are temporally lower than those in developmental TM-1 fibers although they became similar when the TM-1 and im fibers are fully mature. The observation might imply the likelihood of temporal reduction of amorphous regions in developmental im fibers rather than in developmental TM-1 fibers.

  9. Mechanism of formation of humus coatings on mineral surfaces 2. Attenuated total reflectance spectra of hydrophobic and hydrophilic fractions of organic acids from compost leachate on alumina

    USGS Publications Warehouse

    Wershaw, R. L.; Llaguno, E.C.; Leenheer, J.A.; Sperline, R.P.; Song, Y.

    1996-01-01

    Hydrophobic and hydrophilic fractions were isolated from a compost leachate. The adsorption isotherms of both fractions on alumina were measured by attenuated total reflectance infrared spectroscopy. The shapes of the adsorption isotherms of the two fractions were different. The isotherms for the hydrophilic fraction showed little change in surface excess with increasing solution concentration above 4 mg L-1. The isotherms for the hydrophobic fraction, on the other hand, displayed a marked increase in surface excess with increasing solution concentration. This increase is evidence for the formation of aggregates (admicelles or hemimicelles) on the alumina surface. Linear dichroism calculations indicated that more of the carboxylate groups in the adsorbed hydrophobic molecules than in the absorbed hydrophilic fraction were free to rotate. The hindered rotation of the carboxylate groups in the adsorbed hydrophilic-fraction molecules probably indicates that these groups are bound to surface aluminum ions by a bidentate mechanism in which the two oxygen atoms of a single carboxylate group bind to separate aluminum ions.

  10. Chemometric detection of acetaminophen in pharmaceuticals by infrared spectroscopy combined with pattern recognition techniques: comparison of attenuated total reflectance-FTIR and Raman spectroscopy.

    PubMed

    Komsta, Łukasz; Czarnik-Matusewicz, Henryk; Szostak, Roman; Gumieniczek, Anna; Pietraś, Rafał; Skibiński, Robert; Inglot, Tadeusz

    2011-01-01

    This paper presents and discusses the building of discriminant models from attenuated total reflectance (ATR)-FTIR and Raman spectra that were constructed to detect the presence of acetaminophen in over-the-counter pharmaceutical formulations. The datasets, containing 11 spectra of pure substances and 21 spectra of various formulations, were processed by partial least squares (PLS) discriminant analysis. The models found in the present study coped greatly with the discrimination, and their quality parameters were acceptable. A root mean square error of cross-validation was in the 0.14-0.35 range, while a root mean square error of prediction was in the 0.20-0.56 range. It was found that standard normal variate preprocessing had a negligible influence on the quality of ATR-FTIR; in the Raman case, it lowered the prediction error by 2. The influence of variable selection with the uninformative variable elimination by PLS method was studied, and no further model improvement was found.

  11. Detection Limits for Blood on Fabrics Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy and Derivative Processing.

    PubMed

    Lu, Zhenyu; DeJong, Stephanie A; Cassidy, Brianna M; Belliveau, Raymond G; Myrick, Michael L; Morgan, Stephen L

    2017-05-01

    Attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) was used to detect blood stains based on signature protein absorption in the mid-IR region, where intensity changes in the spectrum can be related to blood concentration. Partial least squares regression (PLSR) was applied for multivariate calibrations of IR spectra of blood dilutions on four types of fabric (acrylic, nylon, polyester, and cotton). Gap derivatives (GDs) were applied as a preprocessing technique to optimize the performance of calibration models. We report a much improved IR detection limit (DL) for blood on cotton (2700× in dilution factor units) and the first IR DL reported for blood on nylon (250×). Due to sample heterogeneity caused by fabric hydrophobicity, acrylic fabric produced variable ATR FT-IR spectra that caused poor DLs in concentration units compared to previous work. Polyester showed a similar problem at low blood concentrations that lead to a relatively poor DL as well. However, the increased surface sensitivity and decreased penetration depth of ATR FT-IR make it an excellent choice for detection of small quantities of blood on the front surface of all fabrics tested (0.0010 µg for cotton, 0.0077 µg for nylon, 0.011 µg for acrylic, and 0.0066 µg for polyester).

  12. Changes in hemp secondary fiber production related to technical fiber variability revealed by light microscopy and attenuated total reflectance Fourier transform infrared spectroscopy.

    PubMed

    Fernandez-Tendero, Eva; Day, Arnaud; Legros, Sandrine; Habrant, Anouck; Hawkins, Simon; Chabbert, Brigitte

    2017-01-01

    Interest in hemp (Cannabis sativa L.) is increasing due to the development of a new range of industrial applications based on bast fibers. However the variability of bast fiber yield and quality represents an important barrier to further exploitation. Primary and secondary fiber content was examined in two commercial hemp varieties (Fedora 17, Santhica 27) grown under contrasted sowing density and irrigation conditions. Both growing conditions and hemp varieties impact stem tissue architecture with a large effect on the proportion of secondary fibers but not primary fibers. Attenuated total reflectance infrared spectroscopy allowed the discrimination of manually-isolated native primary fibers and secondary fibers but did not reveal any clustering according to growing conditions and variety. Infrared data were confirmed by wet chemistry analyses that revealed slight but significant differences between primary and secondary fiber cell wall composition. Infrared spectroscopy of technical fibers obtained after mechanical defibering revealed differences with native primary, but not secondary fibers and also discriminated samples obtained from plants grown under different conditions. Altogether the results suggested that the observed variability of hemp technical fibers could be partially explained by i) differences in secondary fiber production and ii) differential behavior during mechanical defibering resulting in unequal separation of primary and secondary fibers.

  13. Changes in hemp secondary fiber production related to technical fiber variability revealed by light microscopy and attenuated total reflectance Fourier transform infrared spectroscopy

    PubMed Central

    Fernandez-Tendero, Eva; Day, Arnaud; Legros, Sandrine; Habrant, Anouck; Hawkins, Simon

    2017-01-01

    Interest in hemp (Cannabis sativa L.) is increasing due to the development of a new range of industrial applications based on bast fibers. However the variability of bast fiber yield and quality represents an important barrier to further exploitation. Primary and secondary fiber content was examined in two commercial hemp varieties (Fedora 17, Santhica 27) grown under contrasted sowing density and irrigation conditions. Both growing conditions and hemp varieties impact stem tissue architecture with a large effect on the proportion of secondary fibers but not primary fibers. Attenuated total reflectance infrared spectroscopy allowed the discrimination of manually-isolated native primary fibers and secondary fibers but did not reveal any clustering according to growing conditions and variety. Infrared data were confirmed by wet chemistry analyses that revealed slight but significant differences between primary and secondary fiber cell wall composition. Infrared spectroscopy of technical fibers obtained after mechanical defibering revealed differences with native primary, but not secondary fibers and also discriminated samples obtained from plants grown under different conditions. Altogether the results suggested that the observed variability of hemp technical fibers could be partially explained by i) differences in secondary fiber production and ii) differential behavior during mechanical defibering resulting in unequal separation of primary and secondary fibers. PMID:28640922

  14. The different molar absorptivities of the secondary structure types in the amide I region: an attenuated total reflection infrared study on globular proteins.

    PubMed

    de Jongh, H H; Goormaghtigh, E; Ruysschaert, J M

    1996-11-01

    Differences in molar absorptivity of the various secondary structures in the amide I region of infrared protein spectra would have a great impact on the interpretation of the data published thus far on protein films studied by attenuated total reflection infrared spectroscopy. In this work, representative values for amide I absorptivities are obtained for 15 different films of globular proteins spread from H2O solutions. The observed intensities are corrected for variations in film thickness and for contributions of hydration water, atmospheric water, and side chains. These absorptivities, together with the reported secondary structure of the proteins investigated, are used to deduce the molar absorptivities of the individual secondary structure types. It is found that the molar absorptivity of beta-strands is 1.4-1.6 times larger than that of alpha-helices, which in turn is 1.3-2.1 times larger than those found for beta-turns or random coiled structures. The implications of our findings for spectral analysis currently used in literature are discussed.

  15. Mid-infrared attenuated total reflection spectroscopy of human stratum corneum using a silver halide fiber probe of square cross-section and adhesive tape stripping

    NASA Astrophysics Data System (ADS)

    Heise, H. M.; Küpper, L.; Butvina, L. N.

    2003-12-01

    Mid-infrared fiber probes allow an extended use of attenuated total reflection (ATR) measurements for topical in vivo skin analysis, which were otherwise not possible with conventional sample compartment accessories. Evanescent wave spectroscopy using a flexible fiber-optic probe from silver halide fibers of square cross-section was employed for stratum corneum characterization and keratinocyte quantification on adhesive tapes. Such a method of quantifying the amount of keratin, which can be repetitively removed from the skin surface by adhesive tape application, is essential for the study of substances topically applied and penetrating into the horny layer. For calibration, the weight of keratinocytes was determined using an ultramicro-balance. Best results were obtained with difference spectroscopy and the evaluation of the amide I absorption band intensity (correlation coefficient r=0.983). Lowest amounts per cm 2 were reached for the range down to 5 μg/cm 2. The heterogeneity in the surface density of keratinocytes clinging to the tape was investigated by microscopy, and the thickness of some individual keratinocytes was tested by ATR-microspectroscopy and atomic force microscopy.

  16. Fourier transform infra-red spectroscopy using an attenuated total reflection probe to distinguish between Japanese larch, pine and citrus plants in healthy and diseased states

    NASA Astrophysics Data System (ADS)

    Gandolfo, D. S.; Mortimer, H.; Woodhall, J. W.; Boonham, N.

    2016-06-01

    FTIR spectroscopy coupled with an Attenuated Total Reflection (ATR) sampling probe has been demonstrated as a technique for detecting disease in plants. Spectral differences were detected in Japanese Larch (Larix kaempferi) infected with Phytophthora ramorum at 3403 cm-1 and 1730 cm-1, from pine (Pinus spp.) infected with Bursaphelenchus xylophilus at 1070 cm-1, 1425 cm-1, 1621 cm-1 and 3403 cm-1 and from citrus (Citrus spp.) infected with 'Candidatus liberibacter' at 960 cm-1, 1087 cm-1, 1109 cm-1, 1154 cm-1, 1225 cm-1, 1385 cm-1, 1462 cm-1, 1707 cm-1, 2882 cm-1, 2982 cm-1 and 3650 cm-1. A spectral marker in healthy citrus has been identified as Pentanone but is absent from the diseased sample spectra. This agrees with recent work by Aksenov, 2014. Additionally, the spectral signature of Cutin was identified in the spectra of Pinus spp. and Citrus spp. and is consistent with work by Dubis, 1999 and Heredia-Guerrero, 2014.

  17. Rapid, nondestructive estimation of surface polymer layer thickness using attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy and synthetic spectra derived from optical principles.

    PubMed

    Weinstock, B André; Guiney, Linda M; Loose, Christopher

    2012-11-01

    We have developed a rapid, nondestructive analytical method that estimates the thickness of a surface polymer layer with high precision but unknown accuracy using a single attenuated total reflection Fourier transform infrared (ATR FT-IR) measurement. Because the method is rapid, nondestructive, and requires no sample preparation, it is ideal as a process analytical technique. Prior to implementation, the ATR FT-IR spectrum of the substrate layer pure component and the ATR FT-IR and real refractive index spectra of the surface layer pure component must be known. From these three input spectra a synthetic mid-infrared spectral matrix of surface layers 0 nm to 10,000 nm thick on substrate is created de novo. A minimum statistical distance match between a process sample's ATR FT-IR spectrum and the synthetic spectral matrix provides the thickness of that sample. We show that this method can be used to successfully estimate the thickness of polysulfobetaine surface modification, a hydrated polymeric surface layer covalently bonded onto a polyetherurethane substrate. A database of 1850 sample spectra was examined. Spectrochemical matrix-effect unknowns, such as the nonuniform and molecularly novel polysulfobetaine-polyetherurethane interface, were found to be minimal. A partial least squares regression analysis of the database spectra versus their thicknesses as calculated by the method described yielded an estimate of precision of ±52 nm.

  18. Preparation and transmission characteristics of a mid-infrared attenuated total reflection hollow waveguide based on a stainless steel capillary tube.

    PubMed

    Wang, Xu; Guo, Hong; Wang, Lin; Yue, Fangyu; Jing, Chengbin; Chu, Junhao

    2016-08-10

    Stainless steel (SUS) capillary tubes were examined as a category of structural tube for establishing a metallic attenuated total reflection (ATR) GeO2 hollow waveguide. GeO2 films were grown on the inner wall of SUS tubes by different liquid phase deposition (LPD) cycles. Fourier transform infrared (FTIR) spectra, scanning electronic microscope (SEM) image, and transmission loss for a CO2 laser were measured to investigate the effects of the LPD cycles on the transmission behavior of the hollow waveguide samples. The film thickness and surface roughness increase with every LPD cycle. The two LPD cycle sample has a film thickness equivalent to the CO2 laser wavelength, while the surface roughness is acceptable. This sample has the lowest transmission loss (0.27  dB/m) among these samples. The bending loss, output beam profile, and full divergence angle (FDA) were further studied. Higher-order modes are excited by bending the sample, inducing additional loss, decentralized beam profile, and larger FDA.

  19. Spectral Mining for Discriminating Blood Origins in the Presence of Substrate Interference via Attenuated Total Reflection Fourier Transform Infrared Spectroscopy: Postmortem or Antemortem Blood?

    PubMed

    Takamura, Ayari; Watanabe, Ken; Akutsu, Tomoko; Ikegaya, Hiroshi; Ozawa, Takeaki

    2017-08-28

    Often in criminal investigations, discrimination of types of body fluid evidence is crucially important to ascertain how a crime was committed. Compared to current methods using biochemical techniques, vibrational spectroscopic approaches can provide versatile applicability to identify various body fluid types without sample invasion. However, their applicability is limited to pure body fluid samples because important signals from body fluids incorporated in a substrate are affected strongly by interference from substrate signals. Herein, we describe a novel approach to recover body fluid signals that are embedded in strong substrate interferences using attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy and an innovative multivariate spectral processing. This technique supported detection of covert features of body fluid signals, and then identified origins of body fluid stains on substrates. We discriminated between ATR FT-IR spectra of postmortem blood (PB) and those of antemortem blood (AB) by creating a multivariate statistics model. From ATR FT-IR spectra of PB and AB stains on interfering substrates (polyester, cotton, and denim), blood-originated signals were extracted by a weighted linear regression approach we developed originally using principal components of both blood and substrate spectra. The blood-originated signals were finally classified by the discriminant model, demonstrating high discriminant accuracy. The present method can identify body fluid evidence independently of the substrate type, which is expected to promote the application of vibrational spectroscopic techniques in forensic body fluid analysis.

  20. Interactions involved in the realignment of membrane-associated helices. An investigation using oriented solid-state NMR and attenuated total reflection Fourier transform infrared spectroscopies.

    PubMed

    Aisenbrey, Christopher; Kinder, Rudolf; Goormaghtigh, Erik; Ruysschaert, Jean-Marie; Bechinger, Burkhard

    2006-03-24

    A series of histidine-containing peptides (LAH4X6) was designed to investigate the membrane interactions of selected side chains. To this purpose, their pH-dependent transitions from in-plane to transmembrane orientations were investigated by attenuated total reflection Fourier transform infrared and oriented solid-state NMR spectroscopies. Peptides of the same family have previously been shown to exhibit antibiotic and DNA transfection activities. Solution NMR spectroscopy indicates that these peptides form amphipathic helical structures in membrane environments, and the technique was also used to characterize the pK values of all histidines in the presence of detergent micelles. Whereas one face of the amphipathic helix is clearly hydrophobic, the opposite side is flanked by four histidines surrounding six leucine, alanine, glycine, tryptophan, or tyrosine residues, respectively. This diversity in peptide composition causes pronounced shifts in the midpoint pH of the in-plane to transmembrane helical transition, which is completely abolished for the peptides carrying the most hydrophilic amino acid residues. These properties open up a conceptually new approach to study in a quantitative manner the hydrophobic as well as specific interactions of amino acids in membranes. Notably, the resulting scale for whole residue transitions from the bilayer interface to the hydrophobic membrane interior is obtained from extended helical sequences in lipid bilayers.

  1. Detection and quantification of soymilk in cow-buffalo milk using Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR).

    PubMed

    Jaiswal, Pranita; Jha, Shyam Narayan; Borah, Anjan; Gautam, Anuj; Grewal, Manpreet Kaur; Jindal, Gaurav

    2015-02-01

    Milk consumption is steadily increasing, especially in India and China, due to rising income. To bridge the gap between supply and demand, unscrupulous milk vendors add milk-like products from vegetable sources (soymilk) to milk without declaration. A rapid detection technique is required to enforce the safety norms of food regulatory authorities. Fourier Transform Infrared (FTIR) spectroscopy has demonstrated potential as a rapid quality monitoring method and was therefore explored for detection of soymilk in milk. In the present work, spectra of milk, soymilk (SM), and milk adulterated with known quantity of SM were acquired in the wave number range of 4000-500cm(-1) using Attenuated Total Reflectance (ATR)-FTIR. The acquired spectra revealed differences amongst milk, SM and adulterated milk (AM) samples in the wave number range of 1680-1058cm(-1). This region encompasses the absorption frequency of amide-I, amide-II, amide-III, beta-sheet protein, α-tocopherol and Soybean Kunitz Trypsin Inhibitor. Principal component analysis (PCA) showed clustering of samples based on SM concentration at 5% level of significance and thus SM could be detected in milk using ATR-FTIR. The SM was best predicted in the range of 1472-1241cm(-1) using multiple linear regression with coefficient of determination (R(2)) of 0.99 and 0.92 for calibration and validation, respectively.

  2. Evaluation of the moisture prediction capability of near-infrared and attenuated total reflectance fourier transform infrared spectroscopy using superdisintegrants as model compounds.

    PubMed

    Uppaluri, Sai G; Bompelliwar, Sai K; Johnson, Paul R; Gupta, Mali R; Al-Achi, Antoine; Stagner, William C; Haware, Rahul V

    2014-12-01

    The superdisintegrants (SDs) moisture content measurement by near-infrared (NIR) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy has been evaluated against thermogravimetric analysis as a reference method. SDs with varying moisture content were used to build calibration and independent model verification data sets. Calibration models were developed based on the water-specific NIR and ATR-FTIR spectral regions using partial least-square regression methods. Because of the NIR water low molar absorptivity, NIR spectroscopy handled higher moisture content (∼81%, w/w) than ATR-FTIR (∼25%, w/w). A two-way ANOVA test was performed to compare R(2) values obtained from measured and predicted moisture content (5%-25%, w/w) of SDs. No statistically significant difference was observed between the predictability of NIR and ATR-FTIR methods (p = 0.3504). However, the interactions between the two independent variables, SDs, and analytical methods were statistically significant (p = 0.0002), indicating that the predictability of the analytical method is material dependent. Thus, it would be important to recognize this highly dependent material and analytical method interaction when using NIR moisture analysis in process analytical technology to analyze and control critical quality and performance attributes of raw materials during processing with the goal of ensuring final product quality attributes.

  3. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy on Intact Dried Leaves of Sage (Salvia officinalis L.): Accelerated Chemotaxonomic Discrimination and Analysis of Essential Oil Composition.

    PubMed

    Gudi, Gennadi; Krähmer, Andrea; Krüger, Hans; Schulz, Hartwig

    2015-10-07

    Sage (Salvia officinalis L.) is cultivated worldwide for its aromatic leaves, which are used as herbal spice, and for phytopharmaceutical applications. Fast analytical strategies for essential oil analysis, performed directly on plant material, would reduce the delay between sampling and analytical results. This would enhance product quality by improving technical control of cultivation. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) method described here provides a reliable calibration model for quantification of essential oil components [EOCs; R(2) = 0.96; root-mean-square error of cross-validation (RMSECV) = 0.249 mL 100 g(-1) of dry matter (DM); and range = 1.115-5.280 mL 100 g(-1) of DM] and main constituents [e.g., α-thujone/β-thujone; R(2) = 0.97/0.86; RMSECV = 0.0581/0.0856 mL 100 g(-1) of DM; and range = 0.010-1.252/0.005-0.893 mL 100 g(-1) of DM] directly on dried intact leaves of sage. Except for drying, no further sample preparation is required for ATR-FTIR, and the measurement time of less than 5 min per sample contrasts with the most common alternative of hydrodistillation followed by gas chromatography analysis, which can take several hours per sample.

  4. Development and validation of an environmentally friendly attenuated total reflectance in the mid-infrared region method for the determination of ethanol content in used engine lubrication oil.

    PubMed

    Hatanaka, Rafael Rodrigues; Sequinel, Rodrigo; Gualtieri, Carlos Eduardo; Tercini, Antônio Carlos Bergamaschi; Flumignan, Danilo Luiz; de Oliveira, José Eduardo

    2013-05-15

    Lubricating oils are crucial in the operation of automotive engines because they both reduce friction between moving parts and protect against corrosion. However, the performance of lubricant oil may be affected by contaminants, such as gasoline, diesel, ethanol, water and ethylene glycol. Although there are many standard methods and studies related to the quantification of contaminants in lubricant oil, such as gasoline and diesel oil, to the best of our knowledge, no methods have been reported for the quantification of ethanol in used Otto cycle engine lubrication oils. Therefore, this work aimed at the development and validation of a routine method based on partial least-squares multivariate analysis combined with attenuated total reflectance in the mid-infrared region to quantify ethanol content in used lubrication oil. The method was validated based on its figures of merit (using the net analyte signal) as follows: limit of detection (0.049%), limit of quantification (0.16%), accuracy (root mean square error of prediction=0.089% w/w), repeatability (0.05% w/w), fit (R(2)=0.9997), mean selectivity (0.047), sensitivity (0.011), inverse analytical sensitivity (0.016% w/w(-1)) and signal-to-noise ratio (max: 812.4 and min: 200.9). The results show that the proposed method can be routinely implemented for the quality control of lubricant oils. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. A Correction Method for Attenuated Total Reflection-Far Ultraviolet Spectra Via the Use of Charge Transfer to Solvent Band Intensities of Iodide in the Ultraviolet Region.

    PubMed

    Ikehata, Akifumi; Goto, Takeyoshi; Morisawa, Yusuke

    2017-07-01

    Attenuated total reflection (ATR) spectra, which are often used in IR analysis, can be transformed into extinction and refraction spectra by Kramers-Kronig transformation (KKT) with Fresnel equations. However, it is often difficult to obtain correct optical indices due to the inherent instrumental functions. This paper proposes a simple practical method for correction of KKT with two parameters, which include all the effects of the instrumental function. In order to obtain the parameters of the instrumental function, absorption ratios of charge transfer to solvent (CTTS) transitions of aqueous iodide ions observed at 195 nm and 230 nm were used as a standard. The absorption indices calculated from the ATR spectra with the parameters correspond reasonably well to those given by the transmittance spectra not only in the UV region but also in the far-ultraviolet (FUV, 120-200 nm) region. By applying the corrected KKT to the ATR-FUV spectra of aqueous potassium halide solutions in the range of 0-2 M, correct features of the absorption spectra of KCl and KBr, whose CTTS bands are thought to be observed in FUV region, were confirmed. It is possible to use the parameters representing the instrument function as long as the instrument is not changed.

  6. Binding of transducin and transducin-derived peptides to rhodopsin studies by attenuated total reflection-Fourier transform infrared difference spectroscopy.

    PubMed Central

    Fahmy, K

    1998-01-01

    Fourier transform infrared difference spectroscopy combined with the attenuated total reflection technique allows the monitoring of the association of transducin with bovine photoreceptor membranes in the dark. Illumination causes infrared absorption changes linked to formation of the light-activated rhodopsin-transducin complex. In addition to the spectral changes normally associated with meta II formation, prominent absorption increases occur at 1735 cm-1, 1640 cm-1, 1550 cm-1, and 1517 cm-1. The D2O sensitivity of the broad carbonyl stretching band around 1735 cm-1 indicates that a carboxylic acid group becomes protonated upon formation of the activated complex. Reconstitution of rhodopsin into phosphatidylcholine vesicles has little influence on the spectral properties of the rhodopsin-transducin complex, whereas pH affects the intensity of the carbonyl stretching band. AC-terminal peptide comprising amino acids 340-350 of the transducin alpha-subunit reproduces the frequencies and isotope sensitivities of several of the transducin-induced bands between 1500 and 1800 cm-1, whereas an N-terminal peptide (aa 8-23) does not. Therefore, the transducin-induced absorption changes can be ascribed mainly to an interaction between the transducin-alpha C-terminus and rhodopsin. The 1735 cm-1 vibration is also seen in the complex with C-terminal peptides devoid of free carboxylic acid groups, indicating that the corresponding carbonyl group is located on rhodopsin. PMID:9726932

  7. Simultaneous probing of bulk liquid phase and catalytic gas-liquid-solid interface under working conditions using attenuated total reflection infrared spectroscopy.

    PubMed

    Meemken, Fabian; Müller, Philipp; Hungerbühler, Konrad; Baiker, Alfons

    2014-08-01

    Design and performance of a reactor set-up for attenuated total reflection infrared (ATR-IR) spectroscopy suitable for simultaneous reaction monitoring of bulk liquid and catalytic solid-liquid-gas interfaces under working conditions are presented. As advancement of in situ spectroscopy an operando methodology for gas-liquid-solid reaction monitoring was developed that simultaneously combines catalytic activity and molecular level detection at the catalytically active site of the same sample. Semi-batch reactor conditions are achieved with the analytical set-up by implementing the ATR-IR flow-through cell in a recycle reactor system and integrating a specifically designed gas feeding system coupled with a bubble trap. By the use of only one spectrometer the design of the new ATR-IR reactor cell allows for simultaneous detection of the bulk liquid and the catalytic interface during the working reaction. Holding two internal reflection elements (IRE) the sample compartments of the horizontally movable cell are consecutively flushed with reaction solution and pneumatically actuated, rapid switching of the cell (<1 s) enables to quasi simultaneously follow the heterogeneously catalysed reaction at the catalytic interface on a catalyst-coated IRE and in the bulk liquid on a blank IRE. For a complex heterogeneous reaction, the asymmetric hydrogenation of 2,2,2-trifluoroacetophenone on chirally modified Pt catalyst the elucidation of catalytic activity/enantioselectivity coupled with simultaneous monitoring of the catalytic solid-liquid-gas interface is shown. Both catalytic activity and enantioselectivity are strongly dependent on the experimental conditions. The opportunity to gain improved understanding by coupling measurements of catalytic performance and spectroscopic detection is presented. In addition, the applicability of modulation excitation spectroscopy and phase-sensitive detection are demonstrated.

  8. Preliminary investigations into macroscopic attenuated total reflection-fourier transform infrared imaging of intact spherical domains: spatial resolution and image distortion.

    PubMed

    Everall, Neil J; Priestnall, Ian M; Clarke, Fiona; Jayes, Linda; Poulter, Graham; Coombs, David; George, Michael W

    2009-03-01

    This paper describes preliminary investigations into the spatial resolution of macro attenuated total reflection (ATR) Fourier transform infrared (FT-IR) imaging and the distortions that arise when imaging intact, convex domains, using spheres as an extreme example. The competing effects of shallow evanescent wave penetration and blurring due to finite spatial resolution meant that spheres within the range 20-140 microm all appeared to be approximately the same size ( approximately 30-35 microm) when imaged with a numerical aperture (NA) of approximately 0.2. A very simple model was developed that predicted this extreme insensitivity to particle size. On the basis of these studies, it is anticipated that ATR imaging at this NA will be insensitive to the size of intact highly convex objects. A higher numerical aperture device should give a better estimate of the size of small spheres, owing to superior spatial resolution, but large spheres should still appear undersized due to the shallow sampling depth. An estimate of the point spread function (PSF) was required in order to develop and apply the model. The PSF was measured by imaging a sharp interface; assuming an Airy profile, the PSF width (distance from central maximum to first minimum) was estimated to be approximately 20 and 30 microm for IR bands at 1600 and 1000 cm(-1), respectively. This work has two significant limitations. First, underestimation of domain size only arises when imaging intact convex objects; if surfaces are prepared that randomly and representatively section through domains, the images can be analyzed to calculate parameters such as domain size, area, and volume. Second, the model ignores reflection and refraction and assumes weak absorption; hence, the predicted intensity profiles are not expected to be accurate; they merely give a rough estimate of the apparent sphere size. Much further work is required to place the field of quantitative ATR-FT-IR imaging on a sound basis.

  9. Simultaneous probing of bulk liquid phase and catalytic gas-liquid-solid interface under working conditions using attenuated total reflection infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Meemken, Fabian; Müller, Philipp; Hungerbühler, Konrad; Baiker, Alfons

    2014-08-01

    Design and performance of a reactor set-up for attenuated total reflection infrared (ATR-IR) spectroscopy suitable for simultaneous reaction monitoring of bulk liquid and catalytic solid-liquid-gas interfaces under working conditions are presented. As advancement of in situ spectroscopy an operando methodology for gas-liquid-solid reaction monitoring was developed that simultaneously combines catalytic activity and molecular level detection at the catalytically active site of the same sample. Semi-batch reactor conditions are achieved with the analytical set-up by implementing the ATR-IR flow-through cell in a recycle reactor system and integrating a specifically designed gas feeding system coupled with a bubble trap. By the use of only one spectrometer the design of the new ATR-IR reactor cell allows for simultaneous detection of the bulk liquid and the catalytic interface during the working reaction. Holding two internal reflection elements (IRE) the sample compartments of the horizontally movable cell are consecutively flushed with reaction solution and pneumatically actuated, rapid switching of the cell (<1 s) enables to quasi simultaneously follow the heterogeneously catalysed reaction at the catalytic interface on a catalyst-coated IRE and in the bulk liquid on a blank IRE. For a complex heterogeneous reaction, the asymmetric hydrogenation of 2,2,2-trifluoroacetophenone on chirally modified Pt catalyst the elucidation of catalytic activity/enantioselectivity coupled with simultaneous monitoring of the catalytic solid-liquid-gas interface is shown. Both catalytic activity and enantioselectivity are strongly dependent on the experimental conditions. The opportunity to gain improved understanding by coupling measurements of catalytic performance and spectroscopic detection is presented. In addition, the applicability of modulation excitation spectroscopy and phase-sensitive detection are demonstrated.

  10. Simultaneous probing of bulk liquid phase and catalytic gas-liquid-solid interface under working conditions using attenuated total reflection infrared spectroscopy

    SciTech Connect

    Meemken, Fabian; Müller, Philipp; Hungerbühler, Konrad; Baiker, Alfons

    2014-08-15

    Design and performance of a reactor set-up for attenuated total reflection infrared (ATR-IR) spectroscopy suitable for simultaneous reaction monitoring of bulk liquid and catalytic solid-liquid-gas interfaces under working conditions are presented. As advancement of in situ spectroscopy an operando methodology for gas-liquid-solid reaction monitoring was developed that simultaneously combines catalytic activity and molecular level detection at the catalytically active site of the same sample. Semi-batch reactor conditions are achieved with the analytical set-up by implementing the ATR-IR flow-through cell in a recycle reactor system and integrating a specifically designed gas feeding system coupled with a bubble trap. By the use of only one spectrometer the design of the new ATR-IR reactor cell allows for simultaneous detection of the bulk liquid and the catalytic interface during the working reaction. Holding two internal reflection elements (IRE) the sample compartments of the horizontally movable cell are consecutively flushed with reaction solution and pneumatically actuated, rapid switching of the cell (<1 s) enables to quasi simultaneously follow the heterogeneously catalysed reaction at the catalytic interface on a catalyst-coated IRE and in the bulk liquid on a blank IRE. For a complex heterogeneous reaction, the asymmetric hydrogenation of 2,2,2-trifluoroacetophenone on chirally modified Pt catalyst the elucidation of catalytic activity/enantioselectivity coupled with simultaneous monitoring of the catalytic solid-liquid-gas interface is shown. Both catalytic activity and enantioselectivity are strongly dependent on the experimental conditions. The opportunity to gain improved understanding by coupling measurements of catalytic performance and spectroscopic detection is presented. In addition, the applicability of modulation excitation spectroscopy and phase-sensitive detection are demonstrated.

  11. Determination of total phenolic content and antioxidant activity of garlic (Allium sativum) and elephant garlic (Allium ampeloprasum) by attenuated total reflectance-Fourier transformed infrared spectroscopy.

    PubMed

    Lu, Xiaonan; Ross, Carolyn F; Powers, Joseph R; Aston, D Eric; Rasco, Barbara A

    2011-05-25

    The total phenolic contents and antioxidant activities of garlics from California, Oregon, Washington, and New York were determined by Fourier transform infrared (FT-IR) spectroscopy (400-4000 cm(-1)). The total phenolic content was quantified [Folin-Ciocalteu assay (FC)] and three antioxidant activity assays, 2,2-diphenyl-picrylhydrazyl (DPPH) assay, Trolox equivalent antioxidant capacity (TEAC) assay, and ferric reducing antioxidant power (FRAP), were employed for reference measurements. Four independent partial least-squares regression (PLSR) models were constructed with spectra from 25 extracts and their corresponding FC, DPPH, TEAC, and FRAP with values for 20 additional extracts predicted (R > 0.95). The standard errors of calibration and standard error of cross-validation were <1.45 (TEAC), 0.36 (FRAP), and 0.33 μmol Trolox/g FW (DPPH) and 0.55 mg gallic acid/g FW (FC). Cluster and dendrogram analyses could segregate garlic grown at different locations. Hydroxyl and phenolic functional groups most closely correlated with garlic antioxidant activity.

  12. Minimally invasive identification of degraded polyester-urethane magnetic tape using attenuated total reflection Fourier transform infrared spectroscopy and multivariate statistics.

    PubMed

    Cassidy, Brianna M; Lu, Zhenyu; Fuenffinger, Nathan C; Skelton, Samantha M; Bringley, Eric J; Nguyen, Linhchi; Myrick, Michael L; Breitung, Eric M; Morgan, Stephen L

    2015-09-15

    Audio recordings are a significant component of the world's modern cultural history and are retained for future generations in libraries, archives, and museums. The vast majority of tapes contain polyester-urethane as the magnetic particle binder, the degradation of which threatens the playability and integrity of these often unique recordings. Magnetic tapes with stored historical data are degrading and need to be identified prior to digitization and/or preservation. We demonstrate the successful differentiation of playable and nonplayable quarter-inch audio tapes, allowing the minimally invasive triage of tape collections. Without such a method, recordings are put at risk during playback, which is the current method for identifying degraded tapes. A total of 133 quarter-inch audio tapes were analyzed by attenuated total reflectance Fourier transform-infrared spectroscopy (ATR FT-IR). Classification of IR spectra in regards to tape playability was accomplished using principal component analysis (PCA) followed by quadratic discriminant analysis (QDA) and K-means cluster analysis. The first principal component suggests intensities at the following wavenumbers to be representative of nonplayable tapes: 1730 cm(-1), 1700 cm(-1), 1255 cm(-1), and 1140 cm(-1). QDA and cluster analysis both successfully identified 93.78% of nonplayable tapes in the calibration set and 92.31% of nonplayable tapes in the test set. This application of IR spectra assessed with multivariate statistical analysis offers a path to greatly improve efficiency of audio tape preservation. This rapid, minimally invasive technique shows potential to replace the manual playback test, a potentially destructive technique, ultimately allowing the safe preservation of culturally valuable content.

  13. Determination of thermally induced trans-fatty acids in soybean oil by attenuated total reflectance fourier transform infrared spectroscopy and gas chromatography analysis.

    PubMed

    Li, An; Ha, Yiming; Wang, Feng; Li, Weiming; Li, Qingpeng

    2012-10-24

    The intake of edible oil containing trans-fatty acids has deleterious effects mainly on the cardiovascular system. Thermal processes such as refining and frying cause the formation of trans-fatty acids in edible oil. This study was conducted to investigate the possible formation of trans-fatty acids because of the heat treatment of soybean oil. The types of trans-fatty acids in heated soybean oil are determined by attenuated total reflectance Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry methods. The effects of the heating temperature on the trans-fatty acids in soybean oil were evaluated using gas chromatography flame ionization detection analysis. Results show that heat treatment at 240 °C causes the formation of trans-fatty acids in soybean oil and the amount of trans-fatty acids increases with heating time. The only peak observed at 966 cm(-1) of the samples indicates the formation of nonconjugated trans isomers in the heated soybean oil. The major types of trans-fatty acids formed were trans-polyunsaturated fatty acids. Significant increases (P < 0.05) in the amounts of two trans-linoleic acids (C18:2-9c,12t and C18:2-9t,12c) and four trans-linolenic acids (C18:3-9c,12c,15t, C18:3-9t,12c,15c, and C18:3-9t,12t,15c/C18:3-9t,12c,15t) in soybean oil heated to temperatures exceeding 200 °C were compared with those of the control sample. The heating temperature and duration should be considered to reduce the formation of trans-fatty acids during thermal treatment.

  14. The problem of 2,4,6-trichloroanisole in cork planks studied by attenuated total reflection infrared spectroscopy: proof of concept.

    PubMed

    Garcia, Ana R; Lopes, Luís F; Brito de Barros, Ricardo; Ilharco, Laura M

    2015-01-14

    Attenuated total reflection infrared spectroscopy (ATR-IR) proved to be a promising detection technique for 2,4,6-trichloroanisole (TCA), which confers organoleptic defects to bottled alcoholic beverages, allowing the proposal of a criterion for cork plank acceptance when meant for stopper production. By analysis of a significant number of samples, it was proved that the presence of TCA, even in very low concentrations, imparts subtle changes to the cork spectra, namely, the growth of two new bands at ∼1417 (νC═C of TCA ring) and 1314 cm–1 (a shifted νCC of TCA) and an increase in the relative intensities of the bands at ∼1039 cm–1 (δCO of polysaccharides) and ∼813 cm–1 (τCH of suberin), the latter by overlapping with intense bands of TCA. These relative intensities were evaluated in comparison to a fingerprint of suberin (νasC–O–C), at 1161 cm–1. On the basis of those spectral variables, a multivariate statistics linear analysis (LDA) was performed to obtain a discriminant function that allows classifying the samples according to whether they contain or not TCA. The methodology proposed consists of a demanding acceptance criterion for cork planks destined for stopper production (with the guarantee of nonexistence of TCA) that results from combining the quantitative results with the absence of the two TCA correlated bands. ATR infrared spectroscopy is a nondestructive and easy to apply technique, both on cork planks and on stoppers, and has proven more restrictive than other techniques used in the cork industry that analyze the cleaning solutions. At the level of proof of concept, the method here proposed is appealing for high-value stopper applications.

  15. A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy

    PubMed Central

    Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

    2016-01-01

    Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion. PMID:27025266

  16. Revealing the Nature and Distribution of Metal Carboxylates in Jackson Pollock's Alchemy (1947) by Micro-Attenuated Total Reflection FT-IR Spectroscopic Imaging.

    PubMed

    Gabrieli, Francesca; Rosi, Francesca; Vichi, Alessandra; Cartechini, Laura; Pensabene Buemi, Luciano; Kazarian, Sergei G; Miliani, Costanza

    2017-01-17

    Protrusions, efflorescence, delamination, and opacity decreasing are severe degradation phenomena affecting oil paints with zinc oxide, one of the most common white pigments of the 20th century. Responsible for these dramatic alterations are the Zn carboxylates (also known as Zn soaps) originated by the interaction of the pigment and the fatty acids resulting from the hydrolysis of glycerides in the oil binding medium. Despite their widespread occurrence in paintings and the growing interest of the scientific community, the process of formation and evolution of Zn soaps is not yet fully understood. In this study micro-attenuated total reflection (ATR)-FT-IR spectroscopic imaging was required for the investigation at the microscale level of the nature and distribution of Zn soaps in the painting Alchemy by J. Pollock (1947, Peggy Guggenheim Collection, Venice) and for comparison with artificially aged model samples. For both actual samples and models, the role of AlSt(OH)2, a jellifying agent commonly added in 20th century paint tube formulations, proved decisive for the formation of zinc stearate-like (ZnSt2) soaps. It was observed that ZnSt2-like soaps first form around the added AlSt(OH)2 particles and then eventually grow within the whole painting stratigraphy as irregularly shaped particles. In some of the Alchemy samples, and diversely from the models, a peculiar distribution of ZnSt2 aggregates arranged as rounded and larger particles was also documented. Notably, in one of these samples, larger agglomerates of ZnSt2 expanding toward the support of the painting were observed and interpreted as the early stage of the formation of internal protrusions. Micro-ATR-FT-IR spectroscopic imaging, thanks to a very high chemical specificity combined with high spatial resolution, was proved to give valuable information for assessing the conservation state of irreplaceable 20th century oil paintings, revealing the chemical distribution of Zn soaps within the paint

  17. Characterization of dopant diffusion within semiconducting polymer and small-molecule films using infrared-active vibrational modes and attenuated total reflectance infrared spectroscopy.

    PubMed

    Maliakal, Ashok J

    2013-09-11

    Understanding dopant diffusion within organic and polymeric semiconductors is of great importance toward the development of organic photovoltaic and electronic devices, many of which require layered structures with controlled doping profiles (e.g., p-n and p-i-n structures). The current paper demonstrates a new method to determine the diffusion and permeability coefficients for dopant diffusion within polymeric and small-molecule organic semiconductors using attenuated total reflectance infrared (ATR-IR) spectroscopy and taking advantage of the intense IR-active vibrational bands created when dopants such as iodine accept charge from a semiconducting polymer to generate polaronic species. The diffusion and permeability coefficients for iodine within poly(3-hexylthiophene) (P3HT) are determined to be 2.5×10(-11)±1.2×10(-11) cm2/s and 2.4×10(-8)±1.2×10(-8) cm2/s·atm, respectively. The approach is applied to P3HT/PCBM (1:1 mass ratio) films, and the diffusion and permeability coefficients through these composite films are determined to be 7.8×10(-11)±2.8×10(-11) cm2/s and 4.8×10(-8)±1.3×10(-8) cm2/s·atm, respectively. Finally, the approach is extended to determining iodine diffusion within the polycrystalline semiconductor tetraphenylporphyrin (TPP) in a bilayer film with P3HT, and the diffusion coefficient of iodine through TPP is determined to be 7.1×10(-14)±1.1×10(-14) cm2/s. Although the current paper determines diffusion and permeability for the dopant iodine, this approach should be applicable to a wide array of dopants and polymeric and small-molecule semiconductors of interest in photovoltaic and electronic applications.

  18. Comparison of Fiber Optic and Conduit Attenuated Total Reflection (ATR) Fourier Transform Infrared (FT-IR) Setup for In-Line Fermentation Monitoring.

    PubMed

    Koch, Cosima; Posch, Andreas E; Herwig, Christoph; Lendl, Bernhard

    2016-12-01

    The performance of a fiber optic and an optical conduit in-line attenuated total reflection mid-infrared (IR) probe during in situ monitoring of Penicillium chrysogenum fermentation were compared. The fiber optic probe was connected to a sealed, portable, Fourier transform infrared (FT-IR) process spectrometer via a plug-and-play interface. The optical conduit, on the other hand, was connected to a FT-IR process spectrometer via a knuckled probe with mirrors that had to be adjusted prior to each fermentation, which were purged with dry air. Penicillin V (PenV) and its precursor phenoxyacetic acid (POX) concentrations were determined by online high-performance liquid chromatography and the obtained concentrations were used as reference to build partial least squares regression models. Cross-validated root-mean-square errors of prediction were found to be 0.2 g L(-1) (POX) and 0.19 g L(-1) (PenV) for the fiber optic setup and 0.17 g L(-1) (both POX and PenV) for the conduit setup. Higher noise-levels and spectrum-to-spectrum variations of the fiber optic setup lead to higher noise of estimated (i.e., unknown) POX and PenV concentrations than was found for the conduit setup. It seems that trade-off has to be made between ease of handling (fiber optic setup) and measurement accuracy (optical conduit setup) when choosing one of these systems for bioprocess monitoring.

  19. A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy.

    PubMed

    Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

    2016-03-30

    Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion.

  20. Chemical Functionalization of Germanium with Dextran Brushes for Immobilization of Proteins Revealed by Attenuated Total Reflection Fourier Transform Infrared Difference Spectroscopy.

    PubMed

    Schartner, Jonas; Hoeck, Nina; Güldenhaupt, Jörn; Mavarani, Laven; Nabers, Andreas; Gerwert, Klaus; Kötting, Carsten

    2015-07-21

    Protein immobilization studied by attenuated total reflection Fourier transform infrared (ATR-FT-IR) difference spectroscopy is an emerging field enabling the study of proteins at atomic detail. Gold or glass surfaces are frequently used for protein immobilization. Here, we present an alternative method for protein immobilization on germanium. Because of its high refractive index and broad spectral window germanium is the best material for ATR-FT-IR spectroscopy of thin layers. So far, this technique was mainly used for protein monolayers, which lead to a limited signal-to-noise ratio. Further, undesired protein-protein interactions can occur in a dense layer. Here, the germanium surface was functionalized with thiols and stepwise a dextran brush was generated. Each step was monitored by ATR-FT-IR spectroscopy. We compared a 70 kDa dextran with a 500 kDa dextran regarding the binding properties. All surfaces were characterized by atomic force microscopy, revealing thicknesses between 40 and 110 nm. To analyze the capability of our system we utilized N-Ras on mono-NTA (nitrilotriacetic acid) functionalized dextran, and the amount of immobilized Ras corresponded to several monolayers. The protein stability and loading capacity was further improved by means of tris-NTA for immobilization. Small-molecule-induced changes were revealed with an over 3 times higher signal-to-noise ratio compared to monolayers. This improvement may allow the observation of very small and so far hidden changes in proteins upon stimulus. Furthermore, we immobilized green fluorescent protein (GFP) and mCherry simultaneously enabling an analysis of the surface by fluorescence microscopy. The absence of a Förster resonance energy transfer (FRET) signal demonstrated a large protein-protein distance, indicating an even distribution of the protein within the dextran.

  1. Ultrasound-enhanced attenuated total reflection mid-infrared spectroscopy in-line probe: acquisition of cell spectra in a bioreactor.

    PubMed

    Koch, Cosima; Brandstetter, Markus; Wechselberger, Patrick; Lorantfy, Bettina; Plata, Maria Reyes; Radel, Stefan; Herwig, Christoph; Lendl, Bernhard

    2015-02-17

    This article presents a novel method for selective acquisition of Fourier transform infrared (FT-IR) spectra of microorganisms in-line during fermentation, using Saccharomyces cerevisiae as an example. The position of the cells relative to the sensitive region of the attenuated total reflection (ATR) FT-IR probe was controlled by combing a commercially available ATR in-line probe with contact-free, gentle particle manipulation by ultrasonic standing waves. A prototype probe was successfully constructed, assembled, and tested in-line during fed-batch fermentations of S. cerevisiae. Control over the position of the cells was achieved by tuning the ultrasound frequency: 2.41 MHz was used for acquisition of spectra of the cells (pushing frequency f(p)) and 1.87 MHz, for retracting the cells from the ATR element, therefore allowing spectra of the medium to be acquired. Accumulation of storage carbohydrates (trehalose and glycogen) inside the cells was induced by a lack of a nitrogen source in the feed medium. These changes in biochemical composition were visible in the spectra of the cells recorded in-line during the application of f(p) and could be verified by reference spectra of dried cell samples recorded off-line with a FT-IR microscope. Comparison of the cell spectra with spectra of trehalose, glycogen, glucose, and mannan, i.e., the major carbohydrates present in S. cerevisiae, and principal components analysis revealed that the changes observed in the cell spectra correlated well with the bands specific for trehalose and glycogen. This proves the applicability and capability of ultrasound-enhanced in-line ATR mid-IR spectroscopy as a real-time PAT method for the in situ monitoring of cellular biochemistry during fermentation.

  2. Ultrasound-Enhanced Attenuated Total Reflection Mid-infrared Spectroscopy In-Line Probe: Acquisition of Cell Spectra in a Bioreactor

    PubMed Central

    2015-01-01

    This article presents a novel method for selective acquisition of Fourier transform infrared (FT-IR) spectra of microorganisms in-line during fermentation, using Saccharomyces cerevisiae as an example. The position of the cells relative to the sensitive region of the attenuated total reflection (ATR) FT-IR probe was controlled by combing a commercially available ATR in-line probe with contact-free, gentle particle manipulation by ultrasonic standing waves. A prototype probe was successfully constructed, assembled, and tested in-line during fed-batch fermentations of S. cerevisiae. Control over the position of the cells was achieved by tuning the ultrasound frequency: 2.41 MHz was used for acquisition of spectra of the cells (pushing frequency fp) and 1.87 MHz, for retracting the cells from the ATR element, therefore allowing spectra of the medium to be acquired. Accumulation of storage carbohydrates (trehalose and glycogen) inside the cells was induced by a lack of a nitrogen source in the feed medium. These changes in biochemical composition were visible in the spectra of the cells recorded in-line during the application of fp and could be verified by reference spectra of dried cell samples recorded off-line with a FT-IR microscope. Comparison of the cell spectra with spectra of trehalose, glycogen, glucose, and mannan, i.e., the major carbohydrates present in S. cerevisiae, and principal components analysis revealed that the changes observed in the cell spectra correlated well with the bands specific for trehalose and glycogen. This proves the applicability and capability of ultrasound-enhanced in-line ATR mid-IR spectroscopy as a real-time PAT method for the in situ monitoring of cellular biochemistry during fermentation. PMID:25582569

  3. In situ determination of transient pKa changes of internal amino acids of bacteriorhodopsin by using time-resolved attenuated total reflection Fourier-transform infrared spectroscopy.

    PubMed

    Zscherp, C; Schlesinger, R; Tittor, J; Oesterhelt, D; Heberle, J

    1999-05-11

    Active proton transfer through membrane proteins is accomplished by shifts in the acidity of internal amino acids, prosthetic groups, and water molecules. The recently introduced step-scan attenuated total reflection Fourier-transform infrared (ATR/FT-IR) spectroscopy was employed to determine transient pKa changes of single amino acid side chains of the proton pump bacteriorhodopsin. The high pKa of D96 (>12 in the ground state) drops to 7.1 +/- 0.2 (in 1 M KCl) during the lifetime of the N intermediate, quantitating the role of D96 as the internal proton donor of the retinal Schiff base. We conclude from experiments on the pH dependence of the proton release reaction and on point mutants where each of the glutamates on the extracellular surface has been exchanged that besides D85 no other carboxylic group changes its protonation state during proton release. However, E194 and E204 interact with D85, the primary proton acceptor of the Schiff base proton. The C==O stretching vibration of D85 undergoes a characteristic pH-dependent shift in frequency during the M state of wild-type bacteriorhodopsin with a pKa of 5.2 (+/-0.3) which is abolished in the single-site mutants E194Q and E204Q and the quadruple mutant E9Q/E74Q/E194Q/E204Q. The double mutation E9Q/E74Q does not affect the lifetime of the intermediates, ruling out any participation of these residues in the proton transfer chain of bacteriorhodopsin. This study demonstrates that transient changes in acidity of single amino acid residues can be quantified in situ with infrared spectroscopy.

  4. In situ studies of butyronitrile adsorption and hydrogenation on Pt/Al2O3 using attenuated total reflection infrared spectroscopy.

    PubMed

    Ortiz-Hernandez, Ivelisse; Williams, Christopher T

    2007-03-13

    The adsorption and hydrogenation of butyronitrile (BN) in hexane on a 5% Pt/Al2O3 catalyst has been studied using in situ attenuated total reflection infrared (ATR-IR) spectroscopy. ATR-IR measurements were conducted on thin ( approximately 10 mum) films of catalyst deposited on Ge wave guides. Multivariate analysis involving classical lease-squares (CLS) and partial least-squares (PLS) modeling was used to aid in the interpretation of the spectroscopic data. During the adsorption of BN over a concentration range from 4 to 40 mM in hexane, no clear evidence for adsorbed N-bound end-on species could be detected. However, a feature at approximately 1635-1640 cm-1 indicated the presence of an adsorbed imine species, with the C=N group existing in a tilted configuration involving a strong degree of pi interaction with the surface. This assignment is bolstered by the detection of N-H stretching bands that are consistent with imine vibrations. This imine-type intermediate is very prominent and shows transient behavior in the presence of solution-phase hydrogen, suggesting that, once formed, it can be converted into amine products that adsorb on the catalyst surface. Evidence for amine formation was observed in the form of N-H stretching and NH2 bending vibrations, with assignments confirmed through comparison studies of butylamine adsorption under identical conditions. Comparisons between Pt/Al2O3 and Al2O3 suggest that there may be some adsorption of these amines on the support surface. The mechanistic implications with regard to heterogeneous nitrile hydrogenation on transition metals under mild conditions are briefly discussed in light of these findings.

  5. Application of Terahertz Attenuated Total Reflection Spectroscopy to Detect Changes in the Physical Properties of Lactose during the Lubrication Process Required for Drug Formulation.

    PubMed

    Dohi, Masafumi; Momose, Wataru; Yamashita, Kazunari; Hakomori, Tadashi; Sato, Shusaku; Noguchi, Shuji; Terada, Katsuhide

    2017-02-01

    Manufacturing the solid dosage form of an orally administered drug requires lubrication to enhance manufacturability, ensuring that critical quality attributes such as disintegration and dissolution of the drug product are maintained during manufacture. Here, to evaluate lubrication performance during manufacture, we used terahertz attenuated total reflection (THz-ATR) spectroscopy to detect differences in the physical characteristics of the lubricated powder. We applied a simple formulation prepared by blending granulated lactose as filler with magnesium stearate as lubricant. A flat tablet was prepared using the lubricated powder to acquire sharp THz-ATR absorption peaks of the samples. First, we investigated the effects of lubricant concentration and compression pressure on preparation of the tablet and then determined the effect of the pressure applied to samples in contact with the ATR prism on sample absorption amplitude. We focused on the differences in the magnitudes of spectra at the lactose-specific frequency. Second, we conducted the dynamic lubrication process using a 120-L mixer to investigate differences in the magnitudes of absorption corresponding to the lactose-specific frequency during lubrication. In both studies, enriching the lubricated powder with a higher concentration of magnesium stearate or prolonging blending time correlated with higher magnitudes of spectra at the lactose-specific frequency. Further, in the dynamic lubrication study, the wettability and disintegration time of the tablets were compared with the absorption spectra amplitudes at the lactose-specific frequency. We conclude that THz-ATR spectroscopy is useful for detecting differences in densities caused by a change in the physical properties of lactose during lubrication.

  6. Drying process of microcrystalline cellulose studied by attenuated total reflection IR spectroscopy with two-dimensional correlation spectroscopy and principal component analysis

    NASA Astrophysics Data System (ADS)

    Watanabe, Akihiko; Morita, Shigeaki; Kokot, Serge; Matsubara, Mika; Fukai, Katsuhiko; Ozaki, Yukihiro

    2006-11-01

    Molecular interactions between microcrystalline cellulose (MCC) and water were investigated by attenuated total reflection infrared (ATR/IR) spectroscopy. Moisture-content-dependent IR spectra during a drying process of wet MCC were measured. In order to distinguish overlapping O-H stretching bands arising from both cellulose and water, principal component analysis (PCA) and, generalized two-dimensional correlation spectroscopy (2DCOS) and second derivative analysis were applied to the obtained spectra. Four typical drying stages were clearly separated by PCA, and spectral variations in each stage were analyzed by 2DCOS. In the drying time range of 0-41 min, a decrease in the broad band around 3390 cm -1 was observed, indicating that bulk water was evaporated. In the drying time range of 49-195 min, decreases in the bands at 3412, 3344 and 3286 cm -1 assigned to the O6H6⋯O3' interchain hydrogen bonds (H-bonds), the O3H3⋯O5 intrachain H-bonds and the H-bonds in Iβ phase in MCC, respectively, were observed. The result of the second derivative analysis suggests that water molecules mainly interact with the O6H6⋯O3' interchain H-bonds. Thus, the H-bonding network in MCC is stabilized by H-bonds between OH groups constructing O6H6⋯O3' interchain H-bonds and water, and the removal of the water molecules induces changes in the H-bonding network in MCC.

  7. Microstructure and Ion Exchange in Stearic Acid Langmuir-Blodgett Films Studied by Fourier Transform Infrared-Attenuated Total Reflection Spectroscopy.

    PubMed

    Li, Chun; Zhao, Bing; Lu, Yiqing; Liang, Yingqiu

    2001-03-01

    Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectra have been recorded of 11-layer Langmuir-Blodgett (LB) films of stearic acid deposited at various surface pressures (0.1, 15, and 35 mN/m), and the molecular orientation angles were evaluated quantitatively, which supplied insight into the molecular order with the alkyl chains tightly packed like crystal in the LB films deposited at the zero and higher surface pressures. These experimental results indicate that, in the Langmuir film as the precursor of LB films, stearic acid molecules self-aggregate to form two-dimensional crystalline domains already even at the zero surface pressure, which results in the inhomogeneity of monolayer. The analysis of dependence of nu(C=O) intensity on the surface pressure, surface density, and subphase temperature leads to the conclusion that the defects in LB films originate from the Langmuir film and be conserved upon deposition. Annealing below 50 degrees C and cooling could improve the monolayer homogeneity, and thus a defect-free or low-defect LB films can be deposited. Furthermore, ion exchange conducted in the LB films, on the other hand, confirms the existence of structure defects in LB films of stearic acid. The polar plane microstructure, lateral transport along the polar planes and the coordination types of stearic acid/cation system may be the rate-limiting process. The results have implication on the possible uses of stearic acid LB films as ion-exchange materials or sensors. Copyright 2001 Academic Press.

  8. Composition of Cypripedium calceolus (Orchidaceae) seeds analyzed by attenuated total reflectance IR spectroscopy: in search of understanding longevity in the ground.

    PubMed

    Barsberg, Søren; Rasmussen, Hanne N; Kodahl, Nete

    2013-10-01

    Orchid seeds are minute and covered with a thin coat, yet they often have a long life after dispersal. They are notorious for low and irregular germination, in nature as well as in vitro. Since orchids are often rare species of conservational and commercial interest, reproduction by seeds is an important concern. The purpose of this study was to learn more about the resilience of these highly specialized seeds and stimulatory processes toward germination. • We studied testa and embryos of Cypripedium calceolus to identify natural components in intact seeds and the impact of 7 yr in soil in its natural habitat. We also analyzed the effects of Ca(OCl)2, used technically to enhance germination for cultivation in vitro. For the first time with this kind of plant material, we used attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, an ideal method for minute sample sizes and surface selectivity. Thus, we could link treatments with changes in seed surface chemistry. • A lignin-like polymer is an essential testa component that undergoes degradation by soil or hypochlorite processes. In both cases, we found a build-up of CaCO3 on the testa, which could interact with lignin to enhance germination. Very minor changes occurred in embryo reserve nutrient content after a long sojourn underground, which supports their continued viability. • We suggest that degradation of lignin and enrichment of the testa surface with CaCO3 are important stimulants of germination both in the habitat and during laboratory sowing.

  9. Attenuated total reflection Fourier transform infrared spectroscopy of redox transitions in photosynthetic reaction centers: comparison of perfusion- and light-induced difference spectra

    NASA Astrophysics Data System (ADS)

    Iwaki, Masayo; Andrianambinintsoa, Sandra; Rich, Peter; Breton, Jacques

    2002-05-01

    Chemically induced Fourier transform infrared difference spectra associated with redox transitions of several primary electron donors and acceptors in photosynthetic reaction centers (RCs) have been compared with the light-induced FTIR difference spectra involving the same cofactors. The RCs are deposited on an attenuated total reflection (ATR) prism and form a film that is enclosed in a flow cell. Redox transitions in the film of RCs can be repetitively induced either by perfusion of buffers poised at different redox potentials or by illumination. The perfusion-induced ATR-FTIR difference spectra for the oxidation of the primary electron donor P in the RCs of the purple bacteria Rb.sphaeroides and Rp.viridis and P700 in the photosystem I of Synechocystis 6803, as well as the Q A-/Q A transition of the quinone acceptor (Q A) in Rb.sphaeroides RCs are reported for the first time. They are compared with the light-induced ATR-FTIR difference spectra P +Q A-/PQ A for the RCs of Rb.sphaeroides and P700 +/P700 for photosystem 1. It is shown that the perfusion-induced and light-induced ATR-FTIR difference spectra recorded on the same RC film display identical signal to noise ratios when they are measured under comparable conditions. The ATR-FTIR difference spectra are very similar to the equivalent FTIR difference spectra previously recorded upon photochemical or electrochemical excitation of these RCs in the more conventional transmission mode. The ATR-FTIR technique requires a smaller amount of sample compared with transmission FTIR and allows precise control of the aqueous environment of the RC films.

  10. Molecular events in deliquescence and efflorescence phase transitions of sodium nitrate particles studied by Fourier transform infrared attenuated total reflection spectroscopy.

    PubMed

    Lu, Pei-Dong; Wang, Feng; Zhao, Li-Jun; Li, Wen-Xue; Li, Xiao-Hong; Dong, Jin-Ling; Zhang, Yun-Hong; Lu, Gao-Qing

    2008-09-14

    The NaNO(3) droplets with sizes of 1-5 microm generated from a nebulizer were deposited on a ZnSe substrate in a Fourier transform infrared attenuated total reflection (FTIR-ATR) chamber. After solidification of the droplets with dry N(2) gas passing through the chamber, the solid NaNO(3) particles were monitored by in situ FTIR-ATR spectra in cycles of deliquescence and efflorescence processes with varying relative humidities (RHs). With an increase in the RH, a dominant peak at approximately 3539 cm(-1), together with three relatively weak peaks at approximately 3400, approximately 3272, and approximately 3167 cm(-1), in the O-H stretching band of water was resolved by the high signal-to-noise ratio FTIR-ATR spectra. The dominant peak and the three relatively weak peaks were contributed by the water monomers and the aggregated water molecules adsorbed on the surfaces of solid NaNO(3) particles, respectively. When the RH approached approximately 72%, slightly lower than the deliquescence RH (74.5%), the band component at approximately 3400 cm(-1) became the main peak, indicating that the water monomers and the aggregated water molecules aggregated to form a thin water layer on the surfaces of solid NaNO(3) particles. A splitting of the nu(3)-NO(3)(-) band at 1363 and 1390 cm(-1) at the RH of approximately 72%, instead of the single nu(3)-NO(3)(-) band at 1357 cm(-1) for the initial solid NaNO(3), was observed. We suggested that this reflected a phase transition from the initial solid to a metastable solid phase of NaNO(3). The metastable solid phase deliquesced completely in the region from approximately 87% to approximately 96% RH according to the fact that the nu(3)-NO(3)(-) band showed two overlapping peaks at 1348 and 1405 cm(-1) similar to those of bulk NaNO(3) solutions. In the efflorescence process of the NaNO(3) droplets, the nu(1)-NO(3)(-) band presented a continuous blueshift from 1049 cm(-1) at approximately 77% RH to 1055 cm(-1) at approximately 36% RH

  11. Soy Protein Isolate and Glycerol Hydrogen Bonding Using Two-Dimensional Correlation (2D-COS) Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy.

    PubMed

    Yan, Zhiwei; Li, Qian; Zhang, Pudun

    2017-01-01

    It is a trend to substitute bioplastics for petroleum-based plastics in food packaging. Glycerol-plasticized soy protein isolate (SPI) is promising as a replacement for traditional petroleum-based plastics. Hydrogen bonding (H-bonding) plays a key role in plasticization of SPI film. However, few publications are concerned with the interactions of SPI and glycerol at the molecular level. In this paper, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy was applied to investigate the effect of H-bonding on the secondary structures of glycerol-plasticized SPI films and thus on the plasticization. An "S" profile of the H-bonding between SPI and glycerol with an abrupt jump in the glycerol range of 10-30% was achieved. For more in-depth investigation of the H-bonding, two-dimensional correlation spectroscopy (2D-COS) and perturbation-correlation moving-window two-dimensional (PCMW2D) analyses were applied to the amide I and II bands of SPI films spectra series. The conformation change sequences under the effect of H-bonding were revealed. When glycerol was involved, it entered into the β-sheet and the H-bonds of the SPI peptide backbone (C = O···H-N-) were replaced by the new H-bonds between SPI and glycerol (C = O···H-O-). The transformations of parallel β-sheet to β-turn in the range of 0-20% and anti-parallel β-sheet to β-turn in the range of 20-35% were obtained. In the 35-60% concentration range, the β-sheet was first changed to a transition state conformation, then together with the β-turn, to the random coil. The 2D-COS results clearly suggest that the conformations of SPI gradually change from the ordered to the less ordered and disordered, which significantly improve the plasticity of SPI film.

  12. Acceleration using total internal reflection

    SciTech Connect

    Fernow, R.C.

    1991-06-07

    This report considers the use of a dielectric slab undergoing total internal reflection as an accelerating structure for charged particle beams. We examine the functional dependence of the electromagnetic fields above the surface of the dielectric for polarized incident waves. We present an experimental arrangement for testing the performance of the method, using apparatus under construction for the Grating Acceleration experiment at Brookhaven National Laboratory. 13 refs., 4 figs., 2 tabs.

  13. Polarimetric total internal reflection biosensing.

    PubMed

    Maisonneuve, Mathieu; Song, In-Hyouk; Patskovsky, Sergiy; Meunier, Michel

    2011-04-11

    In this paper, a concept of polarimetric total internal reflection (TIR) biosensor based on the method of temporal phase modulation is presented. Measurements of the phase difference between s- and p- polarized light combined with their amplitudes allow simultaneous detection of the bulk refractive index and thickness of the surface biofilms. Obtained experimental sensitivity is better than 10(-5) in terms of refractive index unit and 0.5 nm in biolayer thickness. Relatively simple technological implementation of the TIR sensors on the base of inexpensive and transparent substrates opens a number of novel applications in biosensing and microscopy. © 2011 Optical Society of America

  14. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) Mapping Coupled with Multivariate Curve Resolution (MCR) for Studying the Miscibility of Chlorobutyl Rubber/Polyamide-12 Blends.

    PubMed

    Tang, Yongjiao; Jing, Nan; Zhang, Pudun

    2015-11-01

    A series of chlorobutyl rubber/polyamide-12 (CIIR/PA-12) blends compatibilized by different amounts of maleic anhydride (MAH) grafted polypropylene (PP-g-MAH) were investigated by attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) mapping. Multivariate curve resolution (MCR) was used to process the FT-IR images. Both the spectra of pure components in the blends and their concentration distributions in a micro-region were acquired. Our results demonstrated that the blend with 15 parts per hundred rubber PP-g-MAH showed the best miscibility. An amide interphase and an imide interphase were inferred by analyzing the spectra of MCR component 3 of the blends with and without PP-g-MAH, respectively. Correspondingly, two different compatibilizing mechanisms were proposed for these blends.

  15. Prediction of source rock origin by chemometric analysis of fourier transform infrared-attenuated total reflectance spectra of oil petroleum: evaluation of aliphatic and aromatic fractions by self-modeling mixture analysis.

    PubMed

    Abbas, Ouissam; Dupuy, Nathalie; Rebufa, Catherine; Vrielynck, Laurence; Kister, Jacky; Permanyer, Albert

    2006-03-01

    This study describes a new methodology for the interpretation of Fourier transform infrared (FT-IR) attenuated total reflectance (ATR) spectra of Algerian, Brazilian, and Venezuelan crude oils. It is based on a comparative study between a chemometric treatment and the classical one, which refers to indices calculation. In fact, the combined use of FT-IR indices and principal component analysis (PCA) has led to the classification of the studied samples in terms of geographic distribution. Quantitative analysis has been successfully realized by the supervised method partial least squares (PLS), which has permitted the prediction of the locations of oils. We have also applied another mathematical processing method, simple-to-use interactive self-modeling mixture analysis (SIMPLISMA), to evaluate the aromatic and aliphatic composition of the oils by extracting pure spectra representative of the different fractions.

  16. Label-Free Determination of Protein Binding in Aqueous Solution using Overlayer Enhanced Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (OE-ATR-FTIR)

    NASA Astrophysics Data System (ADS)

    Ruthenburg, Travis; Aweda, Tolulope; Park, Simon; Meares, Claude; Land, Donald

    2009-03-01

    Protein binding/affinity studies are often performed using Surface Plasmon Resonance techniques that don't produce much spectral information. Measurement of protein binding affinity using FTIR is traditionally performed using high protein concentration or deuterated solvent. By immobilizing a protein near the surface of a gold-coated germanium internal reflection element interactions can be measured between an immobilized protein and free proteins or small molecules in aqueous solution. By monitoring the on and off rates of these interactions, the dissociation constant for the system can be determined. The dissociation constant for the molecule Yttrium-DOTA binding to the antibody 2D12.5 system was determined to be 100nM. Results will also be presented from our measurements of Bovine Serum Albumin (BSA) binding to anti-BSA.

  17. Application of Attenuated Total Reflectance-Fourier Transformed Infrared (ATR-FTIR) Spectroscopy To Determine the Chlorogenic Acid Isomer Profile and Antioxidant Capacity of Coffee Beans.

    PubMed

    Liang, Ningjian; Lu, Xiaonan; Hu, Yaxi; Kitts, David D

    2016-01-27

    The chlorogenic acid isomer profile and antioxidant activity of both green and roasted coffee beans are reported herein using ATR-FTIR spectroscopy combined with chemometric analyses. High-performance liquid chromatography (HPLC) quantified different chlorogenic acid isomer contents for reference, whereas ORAC, ABTS, and DPPH were used to determine the antioxidant activity of the same coffee bean extracts. FTIR spectral data and reference data of 42 coffee bean samples were processed to build optimized PLSR models, and 18 samples were used for external validation of constructed PLSR models. In total, six PLSR models were constructed for six chlorogenic acid isomers to predict content, with three PLSR models constructed to forecast the free radical scavenging activities, obtained using different chemical assays. In conclusion, FTIR spectroscopy, coupled with PLSR, serves as a reliable, nondestructive, and rapid analytical method to quantify chlorogenic acids and to assess different free radical-scavenging capacities in coffee beans.

  18. A multivariate approach using attenuated total reflectance mid-infrared spectroscopy to measure the surface mannoproteins and β-glucans of yeast cell walls during wine fermentations.

    PubMed

    Moore, John P; Zhang, Song-Lei; Nieuwoudt, Hélène; Divol, Benoit; Trygg, Johan; Bauer, Florian F

    2015-11-18

    Yeast cells possess a cell wall comprising primarily glycoproteins, mannans, and glucan polymers. Several yeast phenotypes relevant for fermentation, wine processing, and wine quality are correlated with cell wall properties. To investigate the effect of wine fermentation on cell wall composition, a study was performed using mid-infrared (MIR) spectroscopy coupled with multivariate methods (i.e., PCA and OPLS-DA). A total of 40 yeast strains were evaluated, including Saccharomyces strains (laboratory and industrial) and non-Saccharomyces species. Cells were fermented in both synthetic MS300 and Chardonnay grape must to stationery phase, processed, and scanned in the MIR spectrum. PCA of the fingerprint spectral region showed distinct separation of Saccharomyces strains from non-Saccharomyces species; furthermore, industrial wine yeast strains separated from laboratory strains. PCA loading plots and the use of OPLS-DA to the data sets suggested that industrial strains were enriched with cell wall proteins (e.g., mannoproteins), whereas laboratory strains were composed mainly of mannan and glucan polymers.

  19. Determination of trans Fat in Selected Fast Food Products and Hydrogenated Fats of India Using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy.

    PubMed

    Khan, Mohd Umar; Hassan, Mohammad Fahimul; Rauf, Abdul

    2017-01-01

    This paper reports the application of a simple and rapid method for the determination of trans fatty acid (TFA) content in some of the selected Indian fast food products and hydrogenated fats using Fourier transform infrared (FTIR) spectroscopy in conjunction with second derivative procedure. FTIR spectroscopy has been successfully applied to trans measurement using the absorbance bands at or near 966 cm(-1) in the FTIR spectra. It was found from the analysis that TFA content of fast food product was ranging from 1.57% to 3.83% of the total fat while for hydrogenated fats, comparatively large quantity of TFA was detected in the range of 3.31% to 4.73%. Since GC-FID is most widely used method for the determination of fatty acid (FA) composition, this method was used for the sake of comparison. Value of regression coefficient was found very close to one (0.99503) with standard deviation of 0.10247 showing a good agreement between GC-FID and proposed ATR-FTIR method.

  20. Digital holography of total internal reflection.

    PubMed

    Ash, William M; Kim, Myung K

    2008-06-23

    We introduce a new microscopy technique termed total internal reflection holographic microscopy (TIRHM). Quantitative phase microscopy by digital holography is used to image the phase profile of light in total internal reflection, which is modulated by the materials present on or near the surface of internal reflection. The imaging characteristics are theoretically modeled and imaging capabilities are experimentally demonstrated.

  1. Attenuated total reflection far-ultraviolet spectroscopy

    NASA Astrophysics Data System (ADS)

    Ozaki, Yukihiro; Morisawa, Yusuke; Goto, Takeyoshi; Tanabe, Ichiro

    2016-09-01

    Recently, far-ultraviolet (FUV) spectroscopy of solid and liquid states has been a matter of keen interest because it provides new possibilities for studying electronic structures and transitions of almost all kinds of molecules. It has also great potential for a variety of applications from quantitative and qualitative analysis of aqueous solutions to environmental and geographical analyses. This review describes the state-of- the-art of FUV spectroscopy; an introduction to FUV spectroscopy, the development of FUV spectrometers, investigations on electronic transitions and structure, its various applications, and future prospects.

  2. Application of in-situ attenuated total reflection-Fourier transform infrared spectroscopy for the understanding of complex reaction mechanism and kinetics: formic acid oxidation on a Pt film electrode at elevated temperatures.

    PubMed

    Chen, Yan Xia; Ye, Shen; Heinen, Martin; Jusys, Zenonas; Osawa, Masatoshi; Behm, R Jürgen

    2006-05-18

    The potential of in-situ Fourier transform infrared (FTIR) spectroscopy measurements in an attenuated total reflection configuration (ATR-FTIRS) for the evaluation of reaction pathways, elementary reaction steps, and their kinetics is demonstrated for formic acid electrooxidation on a Pt film electrode. Quantitative kinetic information on two elementary steps, formic acid dehydration and CO(ad) oxidation, and on the contributions of the related pathways in the dual path reaction mechanism are derived from IR spectroscopic signals in simultaneous electrochemical and ATR-FTIRS measurements over a wide temperature range (25-80 degrees C). Linearly and multiply bonded CO(ad) and bridge-bonded formate are the only formic acid related stable reaction intermediates detected. With increasing temperature, the steady-state IR signal of CO(ad) increases, while that of formate decreases. Reaction rates for CO(ad) formation via formic acid dehydration and for CO(ad) oxidation as well as the activation energies of these processes were determined at different temperatures, potentials, and surface conditions (with and without preadsorbed CO from formic acid dehydration) from the temporal evolution of the IR intensities of CO(ad) during adsorption/reaction transients, using an IR intensity-CO(ad) coverage calibration. At potentials up to 0.75 V and temperatures from 25 to 80 degrees C, the "indirect" CO pathway contributes less than 5% (at potentials < or =0.6 V significantly below 1%) to the total Faradaic reaction current, making the "direct" pathway by far the dominant one under the present reaction conditions. Much higher activation energies for CO(ad) formation and CO(ad) oxidation compared with the effective activation energy of the total reaction, derived from the Faradaic currents, support this conclusion.

  3. A study of surface film formation on LiNi0.8Co0.15Al0.05O2 cathodes u sing attenuated total reflection infrared spectroscopy

    SciTech Connect

    Song, S.-W.; Zhuang, G.V.; Ross Jr., P.N.

    2004-01-19

    The surface films formed on commercial LiNi0.8Co0.15Al0.05O2 cathodes (ATD Gen2) charged from 3.75V to 4.2V vs. Li/Li+ in EC:DEC - 1M LiPF6 were analyzed using ex-situ Fourier transform infrared spectroscopy (FTIR) with the attenuated total reflection (ATR) technique. A surface layer of Li2CO3 is present on the virgin cathode, probably from reaction of the active material with air during the cathode preparation procedure. The Li2CO3 layer disappeared even after soaking in the electrolyte, indicating that the layer dissolved into the electrolyte possibly even before potential cycling of the electrode. IR features only from the binder (PVdF) and a trace of polyamide from the Al current collector were observed on the surfaces of cathodes charged to below 4.2 V, i.e., no surface species from electrolyte oxidation. Some new IR features were, however, found on the cathode charged to 4.2 V and higher. An electrolyte oxidation product was observed that appeared to contain dicarbonyl anhydride and (poly)ester functionalities. The reaction appears to be an indirect electrochemical oxidation with overcharging (removal of > 0.6 Li ions) destabilizing oxygen in the oxide lattice resulting in oxygen transfer to the solvent molecules.

  4. Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy as a Forensic Method to Determine the Composition of Inks Used to Print the United States One-cent Blue Benjamin Franklin Postage Stamps of the 19th Century.

    PubMed

    Brittain, Harry G

    2016-01-01

    Through the combined use of infrared (IR) absorption spectroscopy and attenuated total reflectance (ATR) sampling, the composition of inks used to print the many different types of one-cent Benjamin Franklin stamps of the 19th century has been established. This information permits a historical evaluation of the formulations used at various times, and also facilitates the differentiation of the various stamps from each other. In two instances, the ink composition permits the unambiguous identification of stamps whose appearance is identical, and which (until now) have only been differentiated through estimates of the degree of hardness or softness of the stamp paper, or through the presence or absence of a watermark in the paper. In these instances, the use of ATR Fourier transform infrared spectroscopy (FT-IR) spectroscopy effectively renders irrelevant two 100-year-old practices of stamp identification. Furthermore, since the use of ATR sampling makes it possible to obtain the spectrum of a stamp still attached to its cover, it is no longer necessary to identify these blue Franklin stamps using their cancellation dates. © The Author(s) 2015.

  5. Source Determination of Red Gel Pen Inks using Raman Spectroscopy and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy combined with Pearson's Product Moment Correlation Coefficients and Principal Component Analysis.

    PubMed

    Mohamad Asri, Muhammad Naeim; Mat Desa, Wan Nur Syuhaila; Ismail, Dzulkiflee

    2017-05-08

    The potential combination of two nondestructive techniques, that is, Raman spectroscopy (RS) and attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy with Pearson's product moment correlation (PPMC) coefficient (r) and principal component analysis (PCA) to determine the actual source of red gel pen ink used to write a simulated threatening note, was examined. Eighteen (18) red gel pens purchased from Japan and Malaysia from November to December 2014 where one of the pens was used to write a simulated threatening note were analyzed using RS and ATR-FTIR spectroscopy, respectively. The spectra of all the red gel pen inks including the ink deposited on the simulated threatening note gathered from the RS and ATR-FTIR analyses were subjected to PPMC coefficient (r) calculation and principal component analysis (PCA). The coefficients r = 0.9985 and r = 0.9912 for pairwise combination of RS and ATR-FTIR spectra respectively and similarities in terms of PC1 and PC2 scores of one of the inks to the ink deposited on the simulated threatening note substantiated the feasibility of combining RS and ATR-FTIR spectroscopy with PPMC coefficient (r) and PCA for successful source determination of red gel pen inks. The development of pigment spectral library had allowed the ink deposited on the threatening note to be identified as XSL Poppy Red (CI Pigment Red 112). © 2017 American Academy of Forensic Sciences.

  6. Single-particle mineralogy of Chinese soil particles by the combined use of low-Z particle electron probe X-ray microanalysis and attenuated total reflectance-FT-IR imaging techniques.

    PubMed

    Malek, Md Abdul; Kim, Bowha; Jung, Hae-Jin; Song, Young-Chul; Ro, Chul-Un

    2011-10-15

    Our previous work on the speciation of individual mineral particles of micrometer size by the combined use of attenuated total reflectance FT-IR (ATR-FT-IR) imaging and a quantitative energy-dispersive electron probe X-ray microanalysis technique (EPMA), low-Z particle EPMA, demonstrated that the combined use of these two techniques is a powerful approach for looking at the single-particle mineralogy of externally heterogeneous minerals. In this work, this analytical methodology was applied to characterize six soil samples collected at arid areas in China, in order to identify mineral types present in the samples. The six soil samples were collected from two types of soil, i.e., loess and desert soils, for which overall 665 particles were analyzed on a single particle basis. The six soil samples have different mineralogical characteristics, which were clearly differentiated in this work. As this analytical methodology provides complementary information, the ATR-FT-IR imaging on mineral types, and low-Z particle EPMA on the morphology and elemental concentrations, on the same individual particles, more detailed information can be obtained using this approach than when either low-Z particle EPMA or ATR-FT-IR imaging techniques are used alone, which has a great potential for the characterization of Asian dust and mineral dust particles.

  7. Use of Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy in Direct, Nondestructive, and Rapid Assessment of Developmental Cotton Fibers Grown In Planta and in Culture.

    PubMed

    Liu, Yongliang; Kim, Hee-Jin

    2015-08-01

    Cotton fibers are routinely harvested from cotton plants (in planta), and their end-use qualities depend on their development stages. Cotton fibers are also cultured in controlled laboratory environments, so that cotton researchers can investigate many aspects of experimental protocols in cotton breeding programs at reduced expenses. In this work, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectra of cotton fibers grown in planta and in culture were collected to explore the potential of FT-IR technique as a simple, rapid, and direct method for characterizing the fiber development. Complementary to visual inspection of spectral variations, principal component analysis (PCA) of ATR FT-IR spectra revealed the occurrence of phase transition from primary to secondary cell wall synthesis and also the difference of starting the phase transition between two types of fibers. Like PCA observation, three simple algorithms were capable of monitoring the secondary cell wall formation effectively. Interestingly and uniquely, simple algorithms were able to detect the subtle discrepancies in fibers older than 25 days post-anthesis, which was not apparent from PCA results. The observation indicated the feasibility of FT-IR technique in rapid, routine, nondestructive, and direct assessment of fiber development for cotton physiology and breeding applications.

  8. Microscale Solubility Measurements of Matrix-Assisted Laser Desorption-Ionization (MALDI) Matrices Using Attenuated Total Reflection (ATR) Fourier Transform Infrared Spectroscopy (FT-IR) Coupled with Partial Least Squares (PLS) Analysis.

    PubMed

    Gorre, Elsa; Owens, Kevin G

    2016-11-01

    In this work an attenuated total reflection Fourier transform infrared (FT-IR) absorption based method is used to measure the solubility of two matrix-assisted laser desorption-ionization (MALDI) matrices in a few pure solvents and mixtures of acetonitrile and water using low microliter amounts of solution. Results from a method that averages the values obtained from multiple calibration curves created by manual peak picking are compared to those predicted using a partial least squares (PLS) chemometrics approach. The PLS method provided solubility values that were in good agreement with the manual method with significantly greater ease of analysis. As a test, the solubility of adipic acid in acetone was measured using the two methods of analysis, and the values are in good agreement with solubility values reported in literature. The solubilities of the MALDI matrices α-cyano-4-hydroxy cinnamic acid (CHCA) and sinapinic acid (SA) were measured in a series of mixtures made from acetonitrile (ACN) and water; surprisingly, the results show a highly nonlinear trend. While both CHCA and SA show solubility values of less than 10 mg/mL in the pure solvents, the solubility value for SA increases to 56.3 mg/mL in a 75:25 v/v ACN:water mixture. This can have a significant effect on the matrix-to-analyte ratios in the MALDI experiment when sample protocols call for preparation of a saturated solution of the matrix in the chosen solvent system.

  9. Determination of Trichinella spiralis in pig muscles using Mid-Fourier Transform Infrared Spectroscopy (MID-FTIR) with Attenuated Total Reflectance (ATR) and Soft Independent Modeling of Class Analogy (SIMCA).

    PubMed

    Gómez-De-Anda, Fabián; Dorantes-Álvarez, Lidia; Gallardo-Velázquez, Tzayhri; Osorio-Revilla, Guillermo; Calderón-Domínguez, Georgina; Martínez Labat, Pablo; de-la-Rosa-Arana, Jorge-Luis

    2012-07-01

    The aim of this work was to study the feasibility of detection of Trichinella spiralis in swine meat using Middle Infrared Spectroscopy Fourier Transform with Attenuated Total Reflectance (ATR) and Soft Independent Modeling of Class Analogy (MID-FTIR-ATR-SIMCA). Five male Pigs were orally infected at different larvae concentrations (13,000, 6500, 3500, 1625, 812 larvae/pig) and after 24 weeks the animals were euthanized. Five types of muscles were studied (leg, loin, rib, masseter, and diaphragm). Results showed that MID-FTIR-ATR-SIMCA was useful to determine the presence of T. spiralis in the samples, as the interclass distance between infected and non infected muscles varied from 13.5 to 36.8. This technique was also useful to discriminate among pig muscles, where masseter showed the largest interclass distance, while rib presented the smallest one. In all cases the recognition and rejection rates were 100%, which means that the methodology is capable of accurately separating T. spiralis infected from non infected swine meat.

  10. Feasibility study for the detection of Trichinella spiralis in a murine model using mid-Fourier transform infrared spectroscopy (MID-FTIR) with attenuated total reflectance (ATR) and soft independent modelling of class analogies (SIMCA).

    PubMed

    Gómez-de Anda, Fabián; Gallardo-Velazquez, Tzayhri; Osorio-Revilla, Guillermo; Dorantes-Alvarez, Lidia; Calderon-Dominguez, Georgina; Nogueda-Torres, Benjamín; de-la-Rosa-Arana, Jorge-Luis

    2012-12-21

    Fourier transform infrared (FTIR) spectroscopy with attenuated total reflectance (ATR) and soft independent modelling by class analogies (SIMCA) was used to assess the feasibility of detecting Trichinella spiralis in a murine model. The selected FTIR wavenumber range was 1700-900 cm(-1) and the first derivative of the spectra was subjected to SIMCA analysis. The SIMCA model developed for rat meat spiked with T. spiralis larvae was successfully apply to classify non-infected from infected rat meat with a limit of detection of 3 larvae/10 g rat meat and no false positives with 99% confidence limit. To avoid false positives arising from the presence of other parasites, another chemometric model was developed to demonstrate the capacity of the model to discriminate between Ascaris suum, Taenia solium and T. spiralis. Results confirmed that this method could correctly distinguish these parasites. Additional studies are needed to prove the effectiveness of this technique for other types of muscle meats, including those relevant to human consumption.

  11. In situ attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy monitoring of 1,2-butylene oxide polymerization reaction by using iterative concentration-guided classical least squares.

    PubMed

    Chen, Xiaoyun; Pell, Randy; Sarsani, Sagar; Cramm, Brian; Villa, Carlos; Dixit, Ravindra

    2013-08-01

    There has been rapid growth in the application of in situ optical spectroscopy techniques for reaction and process monitoring recently in both academia and industry. Vibrational spectroscopies such as mid-infrared, near-infrared spectroscopy, and Raman spectroscopy have proven to be versatile and informative. Accurate determination of concentrations, based on highly overlapped spectra, remains a challenge. As an example, 1,2-butylene oxide (BO) polymerization, an important industrial reaction, initiated by propylene glycol (PG) and catalyzed by KOH, is studied in this work in a semi-batch fashion by using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) monitoring. The weak BO absorbance, the constantly changing interference from the product oligomers throughout the course of the reaction, and the change in BO spectral features with system polarity posed challenges for quantitative spectral analysis based on conventional methods. An iterative concentration-guided classical least-squares (ICG-CLS) method was developed to overcome these challenges. Taking advantage of the concentration-domain information, ICG-CLS enabled the estimation of the pure oligomer product spectra at different stages of the semi-batch process, which in turn was used to construct valid CLS models. The ICG-CLS algorithm provides an in situ calibration method that can be broadly applied to reactions of known order. Caveats in its applications are also discussed.

  12. Characterization of silver halide fiber optics and hollow silica waveguides for use in the construction of a mid-infrared attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy probe.

    PubMed

    Damin, Craig A; Sommer, André J

    2013-11-01

    Advances in fiber optic materials have allowed for the construction of fibers and waveguides capable of transmitting infrared radiation. An investigation of the transmission characteristics associated with two commonly used types of infrared-transmitting fibers/waveguides for prospective use in a fiber/waveguide-coupled attenuated total internal reflection (ATR) probe was performed. Characterization of silver halide polycrystalline fiber optics and hollow silica waveguides was done on the basis of the transmission of infrared light using a conventional fiber optic coupling accessory and an infrared microscope. Using the fiber optic coupling accessory, the average percent transmission for three silver halide fibers was 18.1 ± 6.1% relative to a benchtop reflection accessory. The average transmission for two hollow waveguides (HWGs) using the coupling accessory was 8.0 ± 0.3%. (Uncertainties in the relative percent transmission represent the standard deviations.) Reduced transmission observed for the HWGs was attributed to the high numerical aperture of the coupling accessory. Characterization of the fibers/waveguides using a zinc selenide lens objective on an infrared microscope indicated 24.1 ± 7.2% of the initial light input into the silver halide fibers was transmitted. Percent transmission obtained for the HWGs was 98.7 ± 0.1%. Increased transmission using the HWGs resulted from the absence or minimization of insertion and scattering losses due to the hollow air core and a better-matched numerical aperture. The effect of bending on the transmission characteristics of the fibers/waveguides was also investigated. Significant deviations in the transmission of infrared light by the solid-core silver halide fibers were observed for various bending angles. Percent transmission greater than 98% was consistently observed for the HWGs at the bending angles. The combined benefits of high percent transmission, reproducible instrument responses, and increased bending

  13. Raman Scattering with Attentuated - Total-Reflection

    NASA Astrophysics Data System (ADS)

    Reed, Christopher Edward

    Two experiments and supporting calculations were done to see whether using Kretschmann prisms to generate an enhancement by coupling to surface plasmon-polaritons (SPPs) can help in observing Raman scattering by monolayers of molecules. The experiments were done in ultra-high vacuum (UHV). In one, semi-transparent silver films were evaporated onto glass prisms held at 110(DEGREES)K. Attenuated -total-reflectivity (ATR) curves were taken as the prisms warmed to room temperature; the initially very broad and shallow reflectivity dips irreversibly deepened and narrowed, approaching those of films evaporated onto room-temperature substrates. We concluded that delocalized SPPs in cold -evaporated silver films are strongly damped and thus do not contribute to their surface enhanced Raman scattering (SERS) and also that we could not combine SERS with enhancement due to coupling to SPPs. Curve-fitting yielded effective dielectric constants and film thicknesses. In the second experiment we observed Raman scattering by a few monolayers of pyridine adsorbed on smooth silver films deposited at room temperature onto the glass prisms. We used three configurations; light incident from and collected in vacuum, incident through the prism and collected in vacuum, and incident and collected through the prism. The first configuration worked best. Heating of the films limited the incident power we could use. Another limitation was a large background when light was incident and collected through the prism. Possible solutions to these problems are discussed. Using the 2 x 2 matrix method for electromagnetic calculations in multilayers, the reflectivities and electric fields due to incident light were calculated. Combining this with the electromagnetic Green's functions of Mills and Maradudin, which we show work in a more general situation, yields the radiation by an oscillating electric dipole in an arbitrary multilayer. The 2 x 3 matrix giving the polarized radiation in a particular

  14. Novel method for identification and quantification of methanol and ethanol in alcoholic beverages by gas chromatography-Fourier transform infrared spectroscopy and horizontal attenuated total reflectance-Fourier transform infrared spectroscopy.

    PubMed

    Sharma, Kakali; Sharma, Shiba Prasad; Lahiri, Sujit Chandra

    2009-01-01

    Numerous methods are being used to identify and quantify methanol and ethanol in alcoholic beverages, including country liquors. Some of the known methods are density and refractive index measurements, and spectrophotometric measurements using Schiff's reagent or chromatropic acid. Other advanced techniques involve head space gas chromatography (GC), GC-flame ionization detection, high-performance liquid chromatography, enzymatic reactions, and biosensors. However, identification and quantification of methanol and ethanol in beverages can be accurately done using GC-Fourier transform infrared spectroscopy (FTIR) and horizontal attenuated total reflectance (HATR)-FTIR. Identification of alcohols is possible from library matching of the IR spectra obtained from GC-FTIR. In water, methanol and ethanol show a very strong peak for C-O, stretching at 1015.3 and 1044.2 cm(-1), respectively. The strong absorption of vibrational stretching frequency of C-O present in alcohols was used for quantification purposes. The absorptions of C-O group frequency of alcohols in water mixtures were measured using HATR-FTIR with a zinc-selenide crystal. Samples were placed directly on the HATR crystal, with alcohol concentrations ranging from 0.2 to 50.0% (v/v). The plot of absorptions against concentrations of methanol and ethanol obeyed Beer's law (r2 = 0.9998 and 0.9987, respectively), from which alcohol in the mixtures was quantified. Propan-2-ol and n-butanol showed no interference. The method is validated from absorption measurements of known mixtures of standard ethanol in water. This is a simple, specific, rapid, accurate, and nondestructive method of identification and quantification of methanol and ethanol in mixtures. It can be used to ascertain methanol contamination in alcoholic beverages that can lead to death or methanol poisoning by alcohol consumption.

  15. Single-particle characterization of summertime Antarctic aerosols collected at King George Island using quantitative energy-dispersive electron probe X-ray microanalysis and attenuated total reflection Fourier transform-infrared imaging techniques.

    PubMed

    Maskey, Shila; Geng, Hong; Song, Young-Chul; Hwang, Heejin; Yoon, Young-Jun; Ahn, Kang-Ho; Ro, Chul-Un

    2011-08-01

    Single-particle characterization of Antarctic aerosols was performed to investigate the impact of marine biogenic sulfur species on the chemical compositions of sea-salt aerosols in the polar atmosphere. Quantitative energy-dispersive electron probe X-ray microanalysis was used to characterize 2900 individual particles in 10 sets of aerosol samples collected between March 12 and 16, 2009 at King Sejong Station, a Korean scientific research station located at King George Island in the Antarctic. Two size modes of particles, i.e., PM(2.5-10) and PM(1.0-2.5), were analyzed, and four types of particles were identified, with sulfur-containing sea-salt particles being the most abundant, followed by genuine sea-salt particles without sulfur species, iron-containing particles, and other species including CaCO(3)/CaMg(CO(3))(2), organic carbon, and aluminosilicates. When a sulfur-containing sea-salt particle showed an atomic concentration ratio of sulfur to sodium of >0.083 (seawater ratio), it is regarded as containing nonsea-salt sulfate (nss-SO(4)(2-)) and/or methanesulfonate (CH(3)SO(3)(-)), which was supported by attenuated total reflection Fourier transform-infrared imaging measurements. These internal mixture particles of sea-salt/CH(3)SO(3)(-)/SO(4)(2-) were very frequently encountered. As nitrate-containing particles were not encountered, and the air-masses for all of the samples originated from the Pacific Ocean (based on 5-day backward trajectories), the oxidation of dimethylsulfide (DMS) emitted from phytoplanktons in the ocean is most likely to be responsible for the formation of the mixed sea-salt/CH(3)SO(3)(-)/SO(4)(2-) particles.

  16. In Situ Monitoring of the Nascent Pseudomonas fluorescens Biofilm Response to Variations in the Dissolved Organic Carbon Level in Low-Nutrient Water by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy▿

    PubMed Central

    Delille, Anne; Quilès, Fabienne; Humbert, François

    2007-01-01

    Drinking water quality management requires early warning tools which enable water supply companies to detect quickly and to forecast degradation of the microbial quality of drinking water during its transport throughout distribution systems. This study evaluated the feasibility of assessing, in real time, drinking water biostability by monitoring in situ the evolution of the attenuated total reflectance-Fourier transform infrared (ATR-FTIR) fingerprint of a nascent reference biofilm exposed to water being tested. For this purpose, the responses of nascent Pseudomonas fluorescens biofilms to variations in the dissolved organic carbon (DOC) level in tap water were monitored in situ and in real time by ATR-FTIR spectroscopy. Nascent P. fluorescens biofilms consisting of a monolayer of bacteria were formed on the germanium crystal of an ATR flowthrough cell by pumping bacterial suspensions in Luria-Bertani (LB) medium through the cell. Then they were exposed to a continuous flow of dechlorinated sterile tap water supplemented with appropriate amounts of sterile LB medium to obtain DOC concentrations ranging from 1.5 to 11.8 mg/liter. The time evolution of infrared bands related to proteins, polysaccharides, and nucleic acids clearly showed that changes in the DOC concentration resulted in changes in the nascent biofilm ATR-FTIR fingerprint within 2 h after exposure of the biofilm to the water being tested. The initial bacterial attachment, biofilm detachment, and regrowth kinetics determined from changes in the areas of bands associated with proteins and polysaccharides were directly dependent on the DOC level. Furthermore, they were consistent with bacterial adhesion or growth kinetic models and extracellular polymeric substance overproduction or starvation-dependent detachment mechanisms. PMID:17644640

  17. In situ monitoring of the nascent Pseudomonas fluorescens biofilm response to variations in the dissolved organic carbon level in low-nutrient water by attenuated total reflectance-Fourier transform infrared spectroscopy.

    PubMed

    Delille, Anne; Quilès, Fabienne; Humbert, François

    2007-09-01

    Drinking water quality management requires early warning tools which enable water supply companies to detect quickly and to forecast degradation of the microbial quality of drinking water during its transport throughout distribution systems. This study evaluated the feasibility of assessing, in real time, drinking water biostability by monitoring in situ the evolution of the attenuated total reflectance-Fourier transform infrared (ATR-FTIR) fingerprint of a nascent reference biofilm exposed to water being tested. For this purpose, the responses of nascent Pseudomonas fluorescens biofilms to variations in the dissolved organic carbon (DOC) level in tap water were monitored in situ and in real time by ATR-FTIR spectroscopy. Nascent P. fluorescens biofilms consisting of a monolayer of bacteria were formed on the germanium crystal of an ATR flowthrough cell by pumping bacterial suspensions in Luria-Bertani (LB) medium through the cell. Then they were exposed to a continuous flow of dechlorinated sterile tap water supplemented with appropriate amounts of sterile LB medium to obtain DOC concentrations ranging from 1.5 to 11.8 mg/liter. The time evolution of infrared bands related to proteins, polysaccharides, and nucleic acids clearly showed that changes in the DOC concentration resulted in changes in the nascent biofilm ATR-FTIR fingerprint within 2 h after exposure of the biofilm to the water being tested. The initial bacterial attachment, biofilm detachment, and regrowth kinetics determined from changes in the areas of bands associated with proteins and polysaccharides were directly dependent on the DOC level. Furthermore, they were consistent with bacterial adhesion or growth kinetic models and extracellular polymeric substance overproduction or starvation-dependent detachment mechanisms.

  18. Direct determination of sorbitol and sodium glutamate by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) in the thermostabilizer employed in the production of yellow-fever vaccine.

    PubMed

    de Castro, Eduardo da S G; Cassella, Ricardo J

    2016-05-15

    Reference methods for quality control of vaccines usually require treatment of the samples before analysis. These procedures are expensive, time-consuming, unhealthy and require careful manipulation of the sample, making them a potential source of analytical errors. This work proposes a novel method for the quality control of thermostabilizer samples of the yellow fever vaccine employing attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR). The main advantage of the proposed method is the possibility of direct determination of the analytes (sodium glutamate and sorbitol) without any pretreatment of the samples. Operational parameters of the FTIR technique, such as the number of accumulated scans and nominal resolution, were evaluated. The best conditions for sodium glutamate were achieved when 64 scans were accumulated using a nominal resolution of 4 cm(-1). The measurements for sodium glutamate were performed at 1347 cm(-1) (baseline correction between 1322 and 1369 cm(-1)). In the case of sorbitol, the measurements were done at 890cm(-1) (baseline correction between 825 and 910 cm(-1)) using a nominal resolution of 2 cm(-1) with 32 accumulated scans. In both cases, the quantitative variable was the band height. Recovery tests were performed in order to evaluate the accuracy of the method and recovery percentages in the range 93-106% were obtained. Also, the methods were compared with reference methods and no statistical differences were observed. The limits of detection and quantification for sodium glutamate were 0.20 and 0.62% (m/v), respectively, whereas for sorbitol they were 1 and 3.3% (m/v), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Effects of lanthanoid cations on the first electronic transition of liquid water studied using attenuated total reflection far-ultraviolet spectroscopy: ligand field splitting of lanthanoid hydrates in aqueous solutions.

    PubMed

    Goto, Takeyoshi; Ikehata, Akifumi; Morisawa, Yusuke; Higashi, Noboru; Ozaki, Yukihiro

    2012-10-15

    The effects of the lanthanoid cations (Ln(3+)) on the first electronic transition (à ← X̃) of liquid water were studied from the attenuated total reflection far-ultraviolet (ATR-FUV) spectra of trivalent Ln(3+) electrolyte solutions (1 M), except Pm(3+). The à ← X̃ transition energies of the Ln(3+) electrolyte solutions show a distinct tetrad in their dependence on the number of 4f electrons of the Ln(3+) cations. For the half occupation period of the 4f electrons, the à ← X̃ transition energies decrease from La(3+) (4f(0), 8.0375 eV) to Nd(3+) (4f(3), 8.0277 eV) and increase from Sm(3+) (4f(5), 8.0279 eV) to Gd(3+) (4f(7), 8.0374 eV). For the complete occupation period, there are two local minima at Dy(3+) (4f(9), 8.0349 eV) and Yb(3+) (4f(13), 8.0355 eV). The à ← X̃ transition energies of the tetrad nodes (La(3+), Gd(3+), Ho(3+) (4f(10)), and Lu(3+) (4f(14))) increase slightly, as the nuclear charge increases in accordance with the hydration energies of the Ln(3+) cations. The energy difference (ΔE) between the à ← X̃ transition energies and the line between La(3+) and Lu(3+) is largest at Nd(3+) (80.5 cm(-1)) for the half occupation period and at Dy(3+) (26.1 cm(-1)) and Yb(3+) (24.5 cm(-1)) for the complete occupation period. The order of magnitude of ΔE is comparable to the ligand field splitting (LFS) of the ground state multiplets of Ln(3+) complexes. The observed tetrad trend of the à ← X̃ transition energies of the Ln(3+) electrolyte solutions across the 4f period reflects the hydration energies of the Ln(3+) cations and the LFS induced by water ligands.

  20. Electrowetting-actuated optical switch based on total internal reflection.

    PubMed

    Liu, Chao; Wang, Di; Yao, Li-Xiao; Li, Lei; Wang, Qiong-Hua

    2015-04-01

    In this paper we demonstrate a liquid optical switch based on total internal reflection. Two indium tin oxide electrodes are fabricated on the bottom substrate. A conductive liquid (Liquid 1) is placed on one side of the chamber and surrounded by a density-matched silicone oil (Liquid 2). In initial state, when the light beam illuminates the interface of the two liquids, it just meets the conditions of total internal reflection. The light is totally reflected by Liquid 2, and the device shows light-off state. When we apply a voltage to the other side of the indium tin oxide electrode, Liquid 1 stretched towards this side of the substrate and the curvature of the liquid-liquid interface changes. The light beam is refracted by Liquid 1 and the device shows light-on state. So the device can achieve the functions of an optical switch. Because the light beam can be totally reflected by the liquid, the device can attain 100% light intensity attenuation. Our experiments show that the response time from light-on (off) to light-off (on) are 130 and 132 ms, respectively. The proposed optical switch has potential applications in variable optical attenuators, information displays, and light shutters.

  1. Frustrated total internal reflection acoustic field sensor

    DOEpatents

    Kallman, Jeffrey S.

    2000-01-01

    A frustrated total internal reflection acoustic field sensor which allows the acquisition of the acoustic field over an entire plane, all at once. The sensor finds use in acoustic holography and acoustic diffraction tomography. For example, the sensor may be produced by a transparent plate with transparent support members tall enough to support one or more flexible membranes at an appropriate height for frustrated total internal reflection to occur. An acoustic wave causes the membrane to deflect away from its quiescent position and thus changes the amount of light that tunnels through the gap formed by the support members and into the membrane, and so changes the amount of light reflected by the membrane. The sensor(s) is illuminated by a uniform tight field, and the reflection from the sensor yields acoustic wave amplitude and phase information which can be picked up electronically or otherwise.

  2. Total internal reflection ellipsometry: principles and applications.

    PubMed

    Arwin, Hans; Poksinski, Michal; Johansen, Knut

    2004-05-20

    A concept for a measurement technique based on ellipsometry in conditions of total internal reflection is presented. When combined with surface plasmon resonance (SPR) effects, this technique becomes powerful for monitoring and analyzing adsorption and desorption on thin semitransparent metal films as well as for analyzing the semitransparent films themselves. We call this technique total internal reflection ellipsometry (TIRE). The theory of ellipsometry under total internal reflection combined with SPR is discussed for some simple cases. For more advanced cases and to prove the concept, simulations are performed with the Fresnel formalism. The use of TIRE is exemplified by applications in protein adsorption, corrosion monitoring, and adsorption from opaque liquids on metal surfaces. Simulations and experiments show greatly enhanced thin-film sensitivity compared with ordinary ellipsometry.

  3. Reflective attenuator for high-energy laser measurements

    SciTech Connect

    Lehman, John H.; Livigni, David; Li Xiaoyu; Cromer, Christopher L.; Dowell, Marla L

    2008-06-20

    A high-energy laser attenuator in the range of 250 mJ (20 ns pulse width, 10 Hz repetition rate, 1064 nm wavelength) is described. The optical elements that constitute the attenuator are mirrors with relatively low reflectance, oriented at a 45 deg. angle of incidence. By combining three pairs of mirrors, the incoming radiation is collinear and has the same polarization orientation as the exit. We present damage testing and polarization-dependent reflectance measurements for 1064 nm laser light at 45 deg. angle of incidence for molybdenum, silicon carbide, and copper mirrors. A six element, 74 times (18 dB) attenuator is presented as an example.

  4. Reflective attenuator for high-energy laser measurements.

    PubMed

    Lehman, John H; Livigni, David; Li, Xiaoyu; Cromer, Christopher L; Dowell, Marla L

    2008-06-20

    A high-energy laser attenuator in the range of 250 mJ (20 ns pulse width, 10 Hz repetition rate, 1064 nm wavelength) is described. The optical elements that constitute the attenuator are mirrors with relatively low reflectance, oriented at a 45 degrees angle of incidence. By combining three pairs of mirrors, the incoming radiation is collinear and has the same polarization orientation as the exit. We present damage testing and polarization-dependent reflectance measurements for 1064 nm laser light at 45 degrees angle of incidence for molybdenum, silicon carbide, and copper mirrors. A six element, 74 times (18 dB) attenuator is presented as an example.

  5. Total internal reflection photonic crystal prism.

    PubMed

    Schonbrun, Ethan; Abashin, Maxim; Blair, John; Wu, Qi; Park, Wounjhang; Fainman, Yeshaiahu; Summers, Christopher J

    2007-06-25

    An integrated total internal reflection prism is demonstrated that generates a transversely localized evanescent wave along the boundary between a photonic crystal and an etched out trench. The reflection can be described by either the odd symmetry of the Bloch wave or a tangential momentum matching condition. In addition, the Bloch wave propagates through the photonic crystal in a negative refraction regime, which manages diffraction within the prism. A device with three input channels has been fabricated and tested that illuminates different regions of the reflection interface. The reflected wave is then sampled by a photonic wire array, where the individual channels are resolved. Heterodyne near field scanning optical microscopy is used to characterize the spatial phase variation of the evanescent wave and its decay constant.

  6. Total internal reflection laser tools and methods

    DOEpatents

    Zediker, Mark S.; Faircloth, Brian O.; Kolachalam, Sharath K.; Grubb, Daryl L.

    2016-02-02

    There is provided high power laser tools and laser heads that utilize total internal reflection ("TIR") structures to direct the laser beam along a laser beam path within the TIR structure. The TIR structures may be a TIR prism having its hypotenuse as a TIR surface.

  7. Quantitative determination of two polymorphic forms of imatinib mesylate in a drug substance and tablet formulation by X-ray powder diffraction, differential scanning calorimetry and attenuated total reflectance Fourier transform infrared spectroscopy.

    PubMed

    Bellur Atici, Esen; Karlığa, Bekir

    2015-10-10

    Imatinib has been identified as a tyrosine kinase inhibitor that selectively inhibits the Abl tyrosine kinases, including Bcr-Abl. The active substance used in drug product is the mesylate salt form of imatinib, a phenylaminopyrimidine derivative and chemically named as N-(3-(4-(pyridin-3-yl) pyrimidin-2-ylamino)-4-methylphenyl)-4-((4-methylpiperazin-1-yl) methyl)-benzamide methanesulfonic acid salt. It exhibits many polymorphic forms and most stable and commercialized polymorphs are known as α and β forms. Molecules in α and β polymorphic forms exhibit significant conformational differences due to their different intra- and intermolecular interactions, which stabilize their molecular conformations and affect their physicochemical properties such as bulk density, melting point, solubility, stability, and processability. The manufacturing process of a drug tablet included granulation, compression, coating, and drying may cause polymorphic conversions. Therefore, polymorphic content of the drug substance should be controlled during quality control and stability testing. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) methods were evaluated for determination of the polymorphic content of the drug substance and drug product; and PXRD was the most accurate technique and selected as preferred method and validated. Prior to development of a quantification method, pure α and β polymorphs were characterized and used throughout the method development and validation studies. Mixtures with different ratios of α and β forms were scanned using X-ray diffractometer with a scan rate of 0.250°/min over an angular range of 19.5-21.0° 2θ and the peak heights for characteristic peak of β form at 20.5 ± 0.2° 2θ diffraction angle were used to generate a calibration curve. The detection limit of β polymorph in α form imatinib mesylate tablets was found as 4% and

  8. Total Internal Reflection Fluorescence Flow Cytometry

    PubMed Central

    Wang, Jun; Bao, Ning; Paris, Leela L.; Geahlen, Robert L.; Lu, Chang

    2009-01-01

    Total internal reflection fluorescence microscopy (TIRFM) has been widely used to explore biological events that are close to the cell membrane by illuminating fluorescent molecules using the evanescent wave. However, TIRFM is typically limited to the examination of a low number of cells and the results do not reveal potential heterogeneity in the cell population. In this report, we develop an analytical tool referred to as total internal reflection fluorescence flow cytometry (TIRF-FC) to examine the region of the cell membrane with a throughput of ~100–150 cells/s and single cell resolution. We use an elastomeric valve that is partially closed to force flowing cells in contact with the glass surface where the evanescent field resides. We demonstrate that TIRF-FC is able to detect the differences in the subcellular location of an intracellular fluorescent protein. Proper data processing and analysis allows TIRF-FC to be quantitative. With the high throughput, TIRF-FC will be a very useful tool for generating information on cell populations with events and dynamics close to the cell surface. PMID:19007249

  9. Random noise attenuation using an improved anisotropic total variation regularization

    NASA Astrophysics Data System (ADS)

    Gemechu, Diriba; Yuan, Huan; Ma, Jianwei

    2017-09-01

    In seismic data processing, attenuation of random noise from the observed data is the basic step which improves the signal-to-noise ratio (SNR) of seismic data. In this paper, we proposed an anisotropic total bounded variation regularization approach to attenuate noise. An improved constraint convex optimization model is formulated for this approach and then the split Bregman algorithm is used to solve the optimization model. Generalized cross validation (GCV) technique is used to estimate the regularization parameter. Synthetic and real seismic data are considered to show the out performance of the proposed method in terms of event-preserving denoising, in comparison with FX deconvolution, shearlet hard thresholding, and anisotropic total variation methods. The numerical results indicate that the proposed method effectively attenuates random noise by preserving the structure and important features of seismic data.

  10. Frustrated total internal reflection of laser eigenstates

    SciTech Connect

    Balcou, P.; Dutriaux, L.; Bretenaker, F.; Le Floch, A.

    1996-07-01

    The role of frustrated total internal reflection in the dynamics of laser eigenstates is investigated theoretically and experimentally. We first derive the Jones matrix of a frustrating element for a realistic Gaussian beam in a single-pass geometry. We point out the existence of three different angular regimes, namely, a pure frustration regime, an intermediate regime, and a quasi-Fabry{endash}Perot regime. We then explore in each case the nature and the competition between the laser polarization eigenstates. A novel spiraling behavior of the laser parameters is demonstrated when the frustrating gap is varied, along with puzzling polarization-flipping effects, that may modify strongly the conditions that optimize the laser-output power. Experimental results agree with a theoretical model. {copyright} {ital 1996 Optical Society of America.}

  11. Power law relationships for rain attenuation and reflectivity

    NASA Technical Reports Server (NTRS)

    Devasirvatham, D. M. J.; Hodge, D. B.

    1978-01-01

    The equivalent reflectivity, specific attenuation and volumetric backscatter cross section of rain are calculated and tabulated at a number of frequencies from 1 to 500 GHz using classical Mie theory. The first two parameters are shown to be closely approximated as functions of rain rate by the power law aR to the b power. The a's and b's are also tabulated and plotted for convenient reference.

  12. Prisms with total internal reflection as solar reflectors

    DOEpatents

    Rabl, Arnulf; Rabl, Veronika

    1978-01-01

    An improved reflective wall for radiant energy collection and concentration devices is provided. The wall is comprised of a plurality of prisms whose frontal faces are adjacent and which reflect the desired radiation by total internal reflection.

  13. High seismic attenuation in the reflective layers of the Philippine Sea Subduction Zone, Japan

    NASA Astrophysics Data System (ADS)

    Petukhin, Anatoly; Kagawa, Takao

    Intrinsic seismic attenuation gives additional constraints on the physical properties of the deep medium. However, in many cases attenuation is masked by scattering loss. In this work, the high-frequency Q-value, i.e. parameter of seismic attenuation, is studied in the Kii Peninsula segment of the Philippine Sea subduction zone of Japan. The geometrical spreading factor, which is necessary to exclude before inversion of the Q-value, is calculated numerically using a realistic 3-D velocity model and ray approximation. Generally, estimated "total" Q-values agree well with results of other studies and with common expectations based on tectonic structure, except for one striking result: Q-values for the lower crust and the subducting oceanic crust become extremely low, Qtotal˜20-30ƒ . In order to interpret this result we compiled attenuation-related phenomena that were observed in the studied region: (1) the seismogenic upper crust; (2) aseismic lower crust; (3) reflective lower crust (RLC); (4) belt-like zone of the deep low-frequency tremor generation (LFT), that is parallel to the slab; (5) low-frequency earthquakes (LFE); and (6) reflective subducting oceanic crust (SOC). Analysis of ray coverage reveals that anomalously low Q-value in RLC and SOC can be explained mostly by high scattering attenuation (i.e., low Qsc value) in the reflective layers.

  14. Approximating the detection limit of an infrared spectroscopic imaging microscope operating in an attenuated total reflection (ATR) modality: theoretical and empirical results for an instrument using a linear array detector and a 1.5 millimeter germanium hemisphere internal reflection element.

    PubMed

    Lanzarotta, Adam

    2015-01-01

    Theoretical and empirical detection limits have been estimated for aripiprazole (analyte) in alpha lactose monohydrate (matrix model pharmaceutical formulation) using a micro-attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopic imaging instrument equipped with a linear array detector and a 1.5 mm germanium hemisphere internal reflection element (IRE). The instrument yielded a theoretical detection limit of 0.0035% (35 parts per million (ppm)) when operating under diffraction-limited conditions, which was 49 times lower than what was achieved with a traditional macro-ATR instrument operating under practical conditions (0.17%, 1700 ppm). However, these results may not be achievable for most analyses because the detection limits will be particle size limited, rather than diffraction limited, for mixtures with average particle diameters greater than 8.3 μm (most pharmaceutical samples). For example, a theoretical detection limit of 0.028% (280 ppm) was calculated for an experiment operating under particle size-limited conditions where the average particle size was 23.4 μm. These conditions yielded a detection limit of 0.022% (220 ppm) when measured empirically, which was close to the theoretical value and only eight times lower than that of a faster, more simplistic macro-ATR instrument. Considering the longer data acquisition and processing times characteristic of the micro-ATR imaging approach (minutes or even hours versus seconds), the cost-benefit ratio may not often be favorable for the analysis of analytes in matrices that exhibit only a few overlapping absorptions (low-interfering matrices such as alpha lactose monohydrate) using this technique compared to what can be achieved using macro-ATR. However, the advantage was significant for detecting analytes in more complex matrices (those that exhibited several overlapping absorptions with the analyte) because the detection limit of the macro-ATR approach was highly formulation

  15. Error in total ozone measurements arising from aerosol attenuation

    NASA Technical Reports Server (NTRS)

    Thomas, R. W. L.; Basher, R. E.

    1979-01-01

    A generalized least squares method for deducing both total ozone and aerosol extinction spectrum parameters from Dobson spectrophotometer measurements was developed. An error analysis applied to this system indicates that there is little advantage to additional measurements once a sufficient number of line pairs have been employed to solve for the selected detail in the attenuation model. It is shown that when there is a predominance of small particles (less than about 0.35 microns in diameter) the total ozone from the standard AD system is too high by about one percent. When larger particles are present the derived total ozone may be an overestimate or an underestimate but serious errors occur only for narrow polydispersions.

  16. Uranium soft x-ray total attenuation coefficients

    SciTech Connect

    Del Grande, N.K.; Oliver, A.J.

    1981-01-01

    Uranium total attenuation coefficients were measured continuously from 0.84 to 6.0 keV and at selected higher energies using a vacuum single crystal diffractometer and flow-proportional counter. Statistical fluctuations ranged from 0.5% to 2%. The overall accuracy was 3%. Prominent structure was measured within 20 eV of the M/sub 5/ (3.552 keV) and M/sub 4/ (3.728 keV) edges. Jump ratios were determined from log-log polynomial fits to data at energies apart from the near-edge regions. These data were compared with calculations based on a relativistic HFS central potential model and with previously tabulated data.

  17. Total external reflection of X-rays from solid surfaces

    NASA Astrophysics Data System (ADS)

    Stozharov, V. M.

    2017-01-01

    The reflection of X-rays from solid surfaces is comprehensively studied using the measurements of patterns of total external reflection and X-ray diffraction with the aid of a parabolic mirror. Principles for theoretical processing of X-ray patterns are developed. An inverse dependence of the refractive index of X-ray radiation on the interplanar distances in crystallites is obtained.

  18. Questions Students Ask: What Causes Total Internal Reflection?

    ERIC Educational Resources Information Center

    Giancoli, Douglas

    1983-01-01

    Provides a detailed, non-mathematical analysis of total internal reflection based on the interaction of light and matter and the principle of superposition. Discusses factors affecting the critical angle and the percent of the incident beam that is refracted and reflected. (JM)

  19. Multiple attenuation to reflection seismic data using Radon filter and Wave Equation Multiple Rejection (WEMR) method

    SciTech Connect

    Erlangga, Mokhammad Puput

    2015-04-16

    Separation between signal and noise, incoherent or coherent, is important in seismic data processing. Although we have processed the seismic data, the coherent noise is still mixing with the primary signal. Multiple reflections are a kind of coherent noise. In this research, we processed seismic data to attenuate multiple reflections in the both synthetic and real seismic data of Mentawai. There are several methods to attenuate multiple reflection, one of them is Radon filter method that discriminates between primary reflection and multiple reflection in the τ-p domain based on move out difference between primary reflection and multiple reflection. However, in case where the move out difference is too small, the Radon filter method is not enough to attenuate the multiple reflections. The Radon filter also produces the artifacts on the gathers data. Except the Radon filter method, we also use the Wave Equation Multiple Elimination (WEMR) method to attenuate the long period multiple reflection. The WEMR method can attenuate the long period multiple reflection based on wave equation inversion. Refer to the inversion of wave equation and the magnitude of the seismic wave amplitude that observed on the free surface, we get the water bottom reflectivity which is used to eliminate the multiple reflections. The WEMR method does not depend on the move out difference to attenuate the long period multiple reflection. Therefore, the WEMR method can be applied to the seismic data which has small move out difference as the Mentawai seismic data. The small move out difference on the Mentawai seismic data is caused by the restrictiveness of far offset, which is only 705 meter. We compared the real free multiple stacking data after processing with Radon filter and WEMR process. The conclusion is the WEMR method can more attenuate the long period multiple reflection than the Radon filter method on the real (Mentawai) seismic data.

  20. Chemical characterization of latent fingerprints by matrix-assisted laser desorption ionization, time-of-flight secondary ion mass spectrometry, mega electron volt secondary mass spectrometry, gas chromatography/mass spectrometry, X-ray photoelectron spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopic imaging: an intercomparison.

    PubMed

    Bailey, Melanie J; Bright, Nicholas J; Croxton, Ruth S; Francese, Simona; Ferguson, Leesa S; Hinder, Stephen; Jickells, Sue; Jones, Benjamin J; Jones, Brian N; Kazarian, Sergei G; Ojeda, Jesus J; Webb, Roger P; Wolstenholme, Rosalind; Bleay, Stephen

    2012-10-16

    The first analytical intercomparison of fingerprint residue using equivalent samples of latent fingerprint residue and characterized by a suite of relevant techniques is presented. This work has never been undertaken, presumably due to the perishable nature of fingerprint residue, the lack of fingerprint standards, and the intradonor variability, which impacts sample reproducibility. For the first time, time-of-flight secondary ion mass spectrometry, high-energy secondary ion mass spectrometry, and X-ray photoelectron spectroscopy are used to target endogenous compounds in fingerprints and a method is presented for establishing their relative abundance in fingerprint residue. Comparison of the newer techniques with the more established gas chromatography/mass spectrometry and attenuated total reflection Fourier transform infrared spectroscopic imaging shows good agreement between the methods, with each method detecting repeatable differences between the donors, with the exception of matrix-assisted laser desorption ionization, for which quantitative analysis has not yet been established. We further comment on the sensitivity, selectivity, and practicability of each of the methods for use in future police casework or academic research.

  1. Nondestructive Determination of the Age of 20th-Century Oil-Binder Ink Prints Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR): A Case Study with Postage Stamps from the Łódź Ghetto.

    PubMed

    Bower, Nathan W; Blanchet, Conor J K; Epstein, Michael S

    2016-01-01

    The ability to determine the production date for a painting or print would be of great benefit in the forensic detection of fakes and forgeries as well as in art history and conservation. Changes in the pigments used at different times have been invaluable in detecting incongruities that suggest fraud, but relatively little work has been published that uses the chemical changes in oil binders as they dry to determine when an ink print or an oil painting was made. Using attenuated total reflectance-Fourier transform infrared (ATR FT-IR) spectroscopy and samples with known dates, we calibrate the drying of oil binders in inks and paints and cross-validate the paints with pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). We apply the ink calibration to a case study involving the age determination of possible philatelic counterfeits from a World War II Jewish Ghetto in Occupied Poland, obtaining a date of 1946 ± 6 (1 s, n = 9) for the genuine stamps, and 1963 ± 16 (1 s, n = 19) for the various reproductions.

  2. Revisiting A Surprising Demonstration of Total Internal Reflection

    NASA Astrophysics Data System (ADS)

    Lee, Jiwon; Cha, Yu Wha; Jung, Yeon Su; Oh, Eun Ju; Moon, Ye Lin; Kim, Jung Bog

    2016-10-01

    Melton demonstrated a surprising disappearance using total internal reflection. When he put a Florence flask filled with marbles into a water tank and looked straight down from directly above the flask, he was only able to see marbles above a certain water level. When he added more water into the tank above the top line of the marbles, all of the marbles disappeared. He explained this phenomenon as due to a combination of both refraction and total internal reflection. Here, we wanted to develop this surprising idea to create more surprises. However, in our case, we only took the refraction effect from Melton's idea to demonstrate our magic. This idea is supported by various perspectives. For instance, Viss and Sikkema demonstrated the critical angle without using total internal reflection, and James showed the novel optical properties of a submerged light bulb.

  3. A low-reflection coaxial tunable attenuator based on zero refractive index metamaterial

    NASA Astrophysics Data System (ADS)

    Zhang, Kai-Lun; Hou, Zhi-Ling; Wang, Chan-Yuan; Kong, Ling-Bao; Bian, Xin-Ming

    2016-11-01

    In this paper, we design a low-reflection coaxial tunable attenuator with a maximum attenuation of -50 dB by use of zero refractive index metamaterial. Almost no reflection is observed from input port of the proposed structure, due to the easily accessible impedance matching derived from the use of zero refractive index metamaterial. The relationship between attenuation and the air gap width can be well described by an equivalent circuit model. Interestingly, the ratio of input to output voltage is linearly related to the gap width due to the eliminated fringing capacitance by zero-refraction metamaterial, which makes it easy to achieve accurate calibration of the proposed attenuator. The low reflection and linear relationships enable the proposed attenuator to hold promising potential for practical applications.

  4. Method of determining ultrasonic attenuation of tissue using reflective tomographic reconstruction

    SciTech Connect

    Flax, S. W.; Glover, G. H.

    1984-10-09

    Ultrasonic wave attenuation is determined for a plurality of limited volumes of tissue comprising a body under examination by directing ultrasonic waves through each limited volume along a plurality of vectors, determining a measure of attenuation of the limited volume by detecting the frequency shift of reflections of the ultrasonic wave along each vector, and averaging the attenuation of each limited volume from each vector intersecting the limited volume.

  5. Frustration of total internal reflection by a hidden nanowire

    NASA Astrophysics Data System (ADS)

    Frumin, Leonid; Nemykin, Anton; Shapiro, David

    2016-12-01

    A metallic wire embedded in the dielectric substrate leads to frustration of the total internal reflection at the interface between dielectric and free space. The scattering by a gold cylinder is studied in order to exploit the light for hidden objects optical diagnostics. The p-wave incidenting by the angle close to total reflection with the frequency near plasmonic resonance is treated by the modified boundary elements method. The magnetic and electric fields at the interface are calculated. The scattering diagrams are found in near and far field.

  6. Broad Band Intra-Cavity Total Reflection Chemical Sensor

    DOEpatents

    Pipino, Andrew C. R.

    1998-11-10

    A broadband, ultrahigh-sensitivity chemical sensor is provided that allows etection through utilization of a small, extremely low-loss, monolithic optical cavity. The cavity is fabricated from highly transparent optical material in the shape of a regular polygon with one or more convex facets to form a stable resonator for ray trajectories sustained by total internal reflection. Optical radiation enters and exits the monolithic cavity by photon tunneling in which two totally reflecting surfaces are brought into close proximity. In the presence of absorbing material, the loss per pass is increased since the evanescent waves that exist exterior to the cavity at points where the circulating pulse is totally reflected, are absorbed. The decay rate of an injected pulse is determined by coupling out an infinitesimal fraction of the pulse to produce an intensity-versus-time decay curve. Since the change in the decay rate resulting from absorption is inversely proportional to the magnitude of absorption, a quantitative sensor of concentration or absorption cross-section with 1 part-per-million/pass or better sensitivity is obtained. The broadband nature of total internal reflection permits a single device to be used over a broad wavelength range. The absorption spectrum of the surrounding medium can thereby be obtained as a measurement of inverse decay time as a function of wavelength.

  7. Revisit: A Surprising Demonstration of Total Internal Reflection

    ERIC Educational Resources Information Center

    Lee, Jiwon; Cha, Yu Wha; Jung, Yeon Su; Oh, Eun Ju; Moon, Ye Lin; Kim, Jung Bog

    2016-01-01

    Melton demonstrated a surprising disappearance using total internal reflection. When he put a Florence flask filled with marbles into a water tank and looked straight down from directly above the flask, he was only able to see marbles above a certain water level. When he added more water into the tank above the top line of the marbles, all of the…

  8. Revisit: A Surprising Demonstration of Total Internal Reflection

    ERIC Educational Resources Information Center

    Lee, Jiwon; Cha, Yu Wha; Jung, Yeon Su; Oh, Eun Ju; Moon, Ye Lin; Kim, Jung Bog

    2016-01-01

    Melton demonstrated a surprising disappearance using total internal reflection. When he put a Florence flask filled with marbles into a water tank and looked straight down from directly above the flask, he was only able to see marbles above a certain water level. When he added more water into the tank above the top line of the marbles, all of the…

  9. Gaining Insight into Antibubbles via Frustrated Total Internal Reflection

    ERIC Educational Resources Information Center

    Suhr, Wilfried

    2012-01-01

    The interest in the phenomenon of frustrated total internal reflection dates back to the time of Newton. Because of its technological relevance, it has become a standard topic covered by advanced courses in physics. In practical courses optical setups especially designed to demonstrate the phenomenon are commonly used. As an alternative, this…

  10. Rydberg and π-π* transitions in film surfaces of various kinds of nylons studied by attenuated total reflection far-ultraviolet spectroscopy and quantum chemical calculations: peak shifts in the spectra and their relation to nylon structure and hydrogen bondings.

    PubMed

    Morisawa, Yusuke; Yasunaga, Manaka; Sato, Harumi; Fukuda, Ryoichi; Ehara, Masahiro; Ozaki, Yukihiro

    2014-10-09

    Attenuated total reflection far-ultraviolet (ATR-FUV) spectra in the 145-260 nm region were measured for surfaces (thickness 50-200 nm) of various kinds of nylons in cast films to explore their electronic transitions in the FUV region. ATR-FUV spectra show two major bands near 150 and 200 nm in the surface condensed phase of nylons. Transmittance (Tr) spectra were also observed in particular for the analysis of valence excitations. Time-dependent density functional theory (TD-DFT/CAM-B3LYP) calculations were carried out using the model systems to provide the definitive assignments of their absorption spectra and to elucidate their peak shifts in several nylons, in particular, focusing on their crystal alignment structures and intermolecular hydrogen bondings. Two major bands of nylon films near 150 and 200 nm are characterized as σ-Rydberg 3p and π-π* transitions of nylons, respectively. These assignments are also coherent with those of liquid n-alkanes (n = 5-14) and liquid amides observed previously. The Rydberg transitions are delocalized over the hydrocarbon chains, while the π-π* transitions are relatively localized at the amide group. Differences in the peak positions and intensity were found in both ATR- and Tr-FUV spectra for different nylons. A red-shift of the π-π* amide band in the FUV spectra of nylon-6 and nylon-6/6 models in α-form is attributed to the crystal structure pattern and the intermolecular hydrogen bondings, which result in the different delocalization character of the π-π* transitions and transition dipole coupling.

  11. Experimental observation of total-internal-reflection rainbows.

    PubMed

    Adler, Charles L; Lock, James A; Mulholland, Jonathon; Keating, Brian; Ekelman, Diana

    2003-01-20

    A new class of rainbows is created when a droplet is illuminated from the inside by a point light source. The position of the rainbow depends on both the index of refraction of the droplet and the position of the light source, and the rainbow vanishes when the point source is too close to the center of the droplet. Here we experimentally measure the position of the transmission and one-internal-reflection total-internal-reflection rainbows, and the standard (primary) rainbow, as a function of light-source position.

  12. Phase-sensitive silicon-based total internal reflection sensor.

    PubMed

    Patskovsky, S; Meunier, M; Kabashin, A V

    2007-09-17

    A concept of phase-sensitive Si-based Total Internal Reflection bio- and chemical sensor is presented. The sensor uses the reflection of light from an internal edge of a Si prism, which is in contact with analyte material changing its index of refraction (thickness). Changes of the refractive index are monitored by measuring the differential phase shift between p- and s-polarized components of light reflected from the system. We show that due to a high refractive index of Si, such methodology leads to a high sensitivity and dynamic range of measurements. Furthermore, the Si-based platform offers an easy bioimmobilization step and excellent opportunities for the development of multi-channel microsensors taking advantage of the advanced state of development of Si-based microfabrication technologies.

  13. Multiple-channel, total-reflection optic with controllable divergence

    DOEpatents

    Gibson, David M.; Downing, Robert G.

    1997-01-01

    An apparatus and method for providing focused x-ray, gamma-ray, charged particle and neutral particle, including neutron, radiation beams with a controllable amount of divergence are disclosed. The apparatus features a novel use of a radiation blocking structure, which, when combined with multiple-channel total reflection optics, increases the versatility of the optics by providing user-controlled output-beam divergence.

  14. Multiple-channel, total-reflection optic with controllable divergence

    DOEpatents

    Gibson, D.M.; Downing, R.G.

    1997-02-18

    An apparatus and method for providing focused x-ray, gamma-ray, charged particle and neutral particle, including neutron, radiation beams with a controllable amount of divergence are disclosed. The apparatus features a novel use of a radiation blocking structure, which, when combined with multiple-channel total reflection optics, increases the versatility of the optics by providing user-controlled output-beam divergence. 11 figs.

  15. Removing attenuation effects in reflectivity images at 33 and 95 GHz

    NASA Astrophysics Data System (ADS)

    Lohmeier, Stephen P.; Sekelsky, Stephen M.; Firda, John M.

    1997-09-01

    Reflectivity is a fundamental parameter for sensing the morphology and composition of clouds and precipitation. However, attenuation due to varying amounts of precipitation, clouds, and water vapor along the propagation path corrupts reflectivity estimates. In this paper, an algorithm to correct for these effects at 33 and 95 GHz is proposed. This algorithm is then applied to corrupted reflectivity images collected with the University of Massachusetts Microwave Remote Sensing Laboratory (MIRSL) Cloud Profiling Radar System (CPRS), which is a dual-frequency (33 and 95 GHz) , fully-polarimetric, pulse-Doppler, ground-based radar. The attenuation correction algorithm consists of two steps. First, different sources of attenuation along the propagation path are identified by classifying each image into regions of: air, ice particles, liquid droplets, rain, mixed-phase particles, and insects. This is accomplished with a rule-based classifier that relies on collocated measurements of velocity, linear depolarization ratio, and height to make classification decisions. The second step is correcting attenuation along the propagation path in a region appropriate manner. By starting at the ground with the assumption that the reflectivity estimate is unattenuated, and working away from the radar adding a region-appropriate amount to the reflectivity estimate at each range gate, attenuation effects in the image can be largely removed. However, if a mixed-phase region where the rate of attenuation is unknown is encountered along the propagation path, the correction is suspended and an alternative approach that corrects attenuation from the top of the cloud down is used. The complete algorithm was applied to the CPRS data and significantly improved reflectivity estimates.

  16. The role of the reflection coefficient in precision measurement of ultrasonic attenuation

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.

    1984-01-01

    Ultrasonic attenuation measurements using contact, pulse-echo techniques are sensitive to surface roughness and couplant thickness variations. This can reduce considerable inaccuracies in the measurement of the attenuation coefficient for broadband pulses. Inaccuracies arise from variations in the reflection coefficient at the buffer-couplant-sample interface. The reflection coefficient is examined as a function of the surface roughness and corresponding couplant thickness variations. Interrelations with ultrasonic frequency are illustrated. Reliable attenuation measurements are obtained only when the frequency dependence of the reflection coefficient is incorporated in signal analysis. Data are given for nickel 200 samples and a silicon nitride ceramic bar having surface roughness variations in the 0.3 to 3.0 microns range for signal bandwidths in the 50 to 100 MHz range.

  17. Total reflection optical waveguide switching through dielectric chip motion.

    PubMed

    Terui, H; Kobayashi, M

    1981-09-15

    An optical waveguide switch has been realized utilizing the total reflection critical angle controlled by the motion of a dielectric chip set on a waveguide surface. By the contact-noncontact of a GGG chip with the SiO(2)-Ta(2)O(5) waveguide film having a built-in low refractive-index channel, a switching angle of 22.5x and extincion ratio of 12-16 dB were obtained for the TE(0) mode at 0.633-microm wavelength. A 1 x 3 switch that includes two switching positions driven by 6-V electromagnets is demonstrated.

  18. Total Internal Reflection Accounts for the Bright Color of the Saharan Silver Ant.

    PubMed

    Willot, Quentin; Simonis, Priscilla; Vigneron, Jean-Pol; Aron, Serge

    2016-01-01

    The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant's dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant's body.

  19. Total Internal Reflection Accounts for the Bright Color of the Saharan Silver Ant

    PubMed Central

    Aron, Serge

    2016-01-01

    The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant’s dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant’s body. PMID:27073923

  20. TRASER - Total Reflection Amplification of Spontaneous Emission of Radiation

    PubMed Central

    Zachary, Christopher B.; Gustavsson, Morgan

    2012-01-01

    Background and Objective Light and lasers in medical therapy have made dramatic strides since their invention five decades ago. However, the manufacture of lasers can be complex and expensive which often makes treatments limited and costly. Further, no single laser will provide the correct parameters to treat all things. Hence, laser specialists often need multiple devices to practice their specialty. A new concept is described herein that has the potential to replace many lasers and light sources with a single ‘tunable’ device. Study Design/Material and Methods This device amplifies spontaneous emission of radiation by capturing and retaining photons through total internal reflection, hence the acronym Total Reflection Amplification of Spontaneous Emission of Radiation, or TRASER. Results Specific peaks of light can be produced in a reproducible manner with high peak powers of variable pulse durations, a large spot size, and high repetition rate. Conclusion Considering the characteristics and parameters of Traser technology, it is possible that this one device would likely be able to replace the pulsed dye laser and many other light based systems. PMID:22558261

  1. Acoustic total transmission and total reflection in zero-index metamaterials with defects

    NASA Astrophysics Data System (ADS)

    Wei, Qi; Cheng, Ying; Liu, Xiao-jun

    2013-04-01

    The acoustic wave propagation is investigated in the zero-index metamaterial (ZIM) waveguide embedded with defects. Two types of ZIMs, the index-near-zero metamaterials with matched impedance and the density-near-zero metamaterials with mismatched impedance, are examined. Theoretical derivations and numerical simulations show that the total transmission or total reflection can be achieved by properly tailoring the parameters of the defects even in deep-subwavelength scale. Moreover, the transmission is sensitive to the parameters of the defects, suggesting the active control of acoustic transmission by using particular defects with tunable parameters such as porous materials.

  2. Ground-roll attenuation using modified common-offset-common-reflection-surface stacking

    NASA Astrophysics Data System (ADS)

    Rastegar, Seyyed Ali Fa'al; Javaherian, Abdolrahim; Farajkhah, Naser Keshavarz; Monfared, Mehrdad Soleimani; Zarei, Abbas

    2016-06-01

    We modified the common-offset-common-reflection-surface (COCRS) method to attenuate ground roll, the coherent noise typically generated by a low-velocity, low-frequency, and high-amplitude Rayleigh wave. The COCRS operator is based on hyperbolas, thus it fits events with hyperbolic traveltimes such as reflection events in prestack data. Conversely, ground roll is linear in the common-midpoint (CMP) and common-shot gathers and can be distinguished and attenuated by the COCRS operator. Thus, we search for the dip and curvature of the reflections in the common-shot gathers prior to the common-offset section. Because it is desirable to minimize the damage to the reflection amplitudes, we only stack the multicoverage data in the ground-roll areas. Searching the CS gathers before the CO section is another modification of the conventional COCRS stacking. We tested the proposed method using synthetic and real data sets from western Iran. The results of the ground-roll attenuation with the proposed method were compared with results of the f-k filtering and conventional COCRS stacking after f-k filtering. The results show that the proposed method attenuates the aliased and nonaliased ground roll better than the f-k filtering and conventional CRS stacking. However, the computation time was higher than other common methods such as f-k filtering.

  3. Development of a scanning angle total internal reflection Raman spectrometer

    NASA Astrophysics Data System (ADS)

    McKee, Kristopher J.; Smith, Emily A.

    2010-04-01

    A scanning angle total internal reflection (SATIR) Raman spectrometer has been developed for measuring interfacial phenomena with chemical specificity and high axial resolution perpendicular to the interface. The instrument platform is an inverted optical microscope with added automated variable angle optics to control the angle of an incident laser on a prism/sample interface. These optics include two motorized translation stages, the first containing a focusing lens and the second a variable angle galvanometer mirror. The movement of all instrument components is coordinated to ensure that the same sample location and area are probed at each angle. At angles greater than the critical angle, an evanescent wave capable of producing Raman scatter is generated in the sample. The Raman scatter is collected by a microscope objective and directed to a dispersive spectrometer and charge-coupled device detector. In addition to the collected Raman scatter, light reflected from the prism/sample interface is collected to provide calibration parameters that enable modeling the distance over which the Raman scatter is collected for depth profiling measurements. The developed instrument has an incident angle range of 25.5°-75.5°, with a 0.05° angle resolution. Raman scatter can be collected from a ZnSe/organic interface over a range of roughly 35-180 nm. Far from the critical angle, the achieved axial resolution perpendicular to the focal plane is approximately 34 nm. This is roughly a 30-fold improvement relative to confocal Raman microscopy.

  4. High performance, LED powered, waveguide based total internal reflection microscopy

    PubMed Central

    Ramachandran, Srinivasan; Cohen, Daniel A.; Quist, Arjan P.; Lal, Ratnesh

    2013-01-01

    Total internal reflection fluorescence (TIRF) microscopy is a rapidly expanding optical technique with excellent surface sensitivity and limited background fluorescence. Commercially available TIRF systems are either objective based that employ expensive special high numerical aperture (NA) objectives or prism based that restrict integrating other modalities of investigation for structure-function analysis. Both techniques result in uneven illumination of the field of view and require training and experience in optics. Here we describe a novel, inexpensive, LED powered, waveguide based TIRF system that could be used as an add-on module to any standard fluorescence microscope even with low NA objectives. This system requires no alignment, illuminates the entire field evenly, and allows switching between epifluorescence/TIRF/bright field modes without adjustments or objective replacements. The simple design allows integration with other imaging systems, including atomic force microscopy (AFM), for probing complex biological systems at their native nanoscale regimes. PMID:23823601

  5. Diffraction under total internal reflection for micro-fluidic analysis

    NASA Astrophysics Data System (ADS)

    Sarov, Y.; Ivanov, T.; Ivanova, K.; Sarova, V.; Capek, I.; Rangelow, I. W.

    2006-07-01

    This work presents the principles of a novel micro-optical system for micro- and nano-fluidic analysis. It is based on diffraction, occurring in total internal reflection conditions. The developed detector is integrated in an autonomous micro-fluidic device, produced by a unique combination of different techniques for micro- and nano-structuring and micro-machining. The micro-fluidic sensor is examined both experimentally and theoretically with respect to the parameters of the light and the diffraction grating. The most beneficial configurations with respect to maximum sensitivity towards the fluidic optical constants are discussed. Optical experiments show sensitivity of 5×10-4 to the fluidic refractive index and of 3.5×106 m-1 to the absorption coefficient. Envisioned applications of the integrated micro-sensor are concentration and composition analysis, environmental protection control, medical, biological and chemical diagnostics, and so on.

  6. A 'pocket guide' to total internal reflection fluorescence.

    PubMed

    Martin-Fernandez, M L; Tynan, C J; Webb, S E D

    2013-10-01

    The phenomenon of total internal reflection fluorescence (TIRF) was placed in the context of optical microscopy by Daniel Axelrod over three decades ago. TIRF microscopy exploits the properties of an evanescent electromagnetic field to optically section sample regions in the close vicinity of the substrate where the field is induced. The first applications in cell biology targeted investigation of phenomena at the basolateral plasma membrane. The most notable application of TIRF is single-molecule experiments, which can provide information on fluctuation distributions and rare events, yielding novel insights on the mechanisms governing the molecular interactions that underpin many fundamental processes within the cell. This short review intends to provide a 'one stop shop' explanation of the electromagnetic theory behind the remarkable properties of the evanescent field, guide the reader through the principles behind building or choosing your own TIRF system and consider how the most popular applications of the method exploit the evanescent field properties.

  7. Frustrated Total Internal Reflection applied to Quantum Tunneling

    NASA Astrophysics Data System (ADS)

    Hull, Nathaniel; Yan, Jia-An

    The objective of this project is to demonstrate an optical phenomenon, frustrated total internal reflection (FTIR), by numerically solving the time-dependent Schrodinger equation (TDSE) in quantum mechanics, and to illustrate the correlations between FTIR and the quantum tunneling in one-dimensional quantum structures. We will use a MATLAB program to numerically propagate a Gaussian wave packet to penetrate finite square barriers. The transmission coefficient is then calculated as a function of the distance between two rectangular barriers/wells. The results will be useful to elucidate the correlations between optical FTIR and quantum tunneling. This work was supported by the FCSM Undergraduate Research Committee, the FCSM Fisher General Endowment and the FDRC Grant (OSPR No. 140269) at Towson University.

  8. Attenuation of front-end reflections in an impulse radar using high-speed switching

    NASA Astrophysics Data System (ADS)

    Mazzaro, Gregory J.; Ressler, Marc A.; Smith, Gregory D.

    2011-06-01

    Pulse reflection between front-end components is a common problem for impulse radar systems. Such reflections arise because radio frequency components are rarely impedance-matched over an ultra-wide bandwidth. Any mismatch between components causes a portion of the impulse to reflect within the radar front-end. If the reflection couples into the transmit antenna, the radar emits an unintended, delayed and distorted replica of the intended radar transmission. These undesired transmissions reflect from the radar environment, produce echoes in the radar image, and generate false alarms in the vicinity of actual targets. The proposed solution for eliminating these echoes, without redesigning the transmit antenna, is to dissipate pulse reflections in a matched load before they are emitted. A high-speed switch directs the desired pulse to the antenna and redirects the undesired reflection from the antenna to a matched load. The Synchronous Impulse Reconstruction (SIRE) radar developed by the Army Research Laboratory (ARL) is the case-study. This paper reviews the current front-end design, provides a recent radar image which displays the aforementioned echoes, and describes the switch-cable-load circuit solution for eliminating the echoes. The consequences of inserting each portion of the new hardware into the radar front-end are explained. Measurements on the front-end with the high-speed switch show an attenuation of the undesired pulse transmissions of more than 18 dB and an attenuation in the desired pulse transmission of less than 3 dB.

  9. Diffuse Reflectance Spectroscopy for Total Carbon Analysis of Hawaiian Soils

    NASA Astrophysics Data System (ADS)

    McDowell, M. L.; Bruland, G. L.; Deenik, J. L.; Grunwald, S.; Uchida, R.

    2010-12-01

    Accurate assessment of total carbon (Ct) content is important for fertility and nutrient management of soils, as well as for carbon sequestration studies. The non-destructive analysis of soils by diffuse reflectance spectroscopy (DRS) is a potential supplement or alternative to the traditional time-consuming and costly combustion method of Ct analysis, especially in spatial or temporal studies where sample numbers are large. We investigate the use of the visible to near-infrared (VNIR) and mid-infrared (MIR) spectra of soils coupled with chemometric analysis to determine their Ct content. Our specific focus is on Hawaiian soils of agricultural importance. Though this technique has been introduced to the soil community, it has yet to be fully tested and used in practical applications for all soil types, and this is especially true for Hawaii. In short, DRS characterizes and differentiates materials based on the variation of the light reflected by a material at certain wavelengths. This spectrum is dependent on the material’s composition, structure, and physical state. Multivariate chemometric analysis unravels the information in a set of spectra that can help predict a property such as Ct. This study benefits from the remarkably diverse soils of Hawaii. Our sample set includes 216 soil samples from 145 pedons from the main Hawaiian Islands archived at the National Soil Survey Center in Lincoln, NE, along with more than 50 newly-collected samples from Kauai, Oahu, Molokai, and Maui. In total, over 90 series from 10 of the 12 soil orders are represented. The Ct values of these samples range from < 1% - 55%. We anticipate that the diverse nature of our sample set will ensure a model with applicability to a wide variety of soils, both in Hawaii and globally. We have measured the VNIR and MIR spectra of these samples and obtained their Ct values by dry combustion. Our initial analyses are conducted using only samples obtained from the Lincoln archive. In this

  10. Around-the-objective total internal reflection fluorescence microscopy

    PubMed Central

    Burghardt, Thomas P.; Hipp, Andrew D.; Ajtai, Katalin

    2009-01-01

    Total internal reflection fluorescence (TIRF) microscopy uses the evanescent field on the aqueous side of a glass/aqueous interface to selectively illuminate fluorophores within ~100 nm of the interface. Applications of the method include epi-illumination TIRF, where the exciting light is refracted by the microscope objective to impinge on the interface at incidence angles beyond critical angle, and prism-based TIRF, where exciting light propagates to the interface externally to the microscope optics. The former has higher background autofluorescence from the glass elements of the objective where the exciting beam is focused, and the latter does not collect near-field emission from the fluorescent sample. Around-the-objective TIRF, developed here, creates the evanescent field by conditioning the exciting laser beam to propagate through the submillimeter gap created by the oil immersion high numerical aperture objective and the glass coverslip. The approach eliminates background light due to the admission of the laser excitation to the microscopic optics while collecting near-field emission from the dipoles excited by the ~50 nm deep evanescent field. PMID:19904308

  11. Attenuator design for organs at risk in total body irradiation using a translation technique

    SciTech Connect

    Lavallee, Marie-Claude; Aubin, Sylviane; Chretien, Mario; Larochelle, Marie; Beaulieu, Luc

    2008-05-15

    Total body irradiation (TBI) is an efficient part of the treatment for malignant hematological diseases. Dynamic TBI techniques provide great advantages (e.g., dose homogeneity, patient comfort) while overcoming treatment room space restrictions. However, with dynamic techniques come additional organs at risk (OAR) protection challenges. In most dynamic TBI techniques, lead attenuators are used to diminish the dose received by the OARs. The purpose of this study was to characterize the dose deposition under various shapes of attenuators in static and dynamic treatments. This characterization allows for the development of a correction method to improve attenuator design in dynamic treatments. The dose deposition under attenuators at different depths in dynamic treatment was compared with the static situation based on two definitions: the coverage areas and the penumbra regions. The coverage area decreases with depth in dynamic treatment while it is stable for the static situation. The penumbra increases with depth in both treatment modes, but the increasing rate is higher in the dynamic situation. Since the attenuator coverage is deficient in the dynamic treatment mode, a correction method was developed to modify the attenuator design in order to improve the OAR protection. The correction method is divided in two steps. The first step is based on the use of elongation charts, which provide appropriate attenuator coverage and acceptable penumbra for a specific depth. The second point is a correction method for the thoracic inclination, which can introduce an orientation problem in both static and dynamic treatments. This two steps correction method is simple to use and personalized to each patient's anatomy. It can easily be adapted to any dynamic TBI techniques.

  12. Attenuator design for organs at risk in total body irradiation using a translation technique.

    PubMed

    Lavallée, Marie-Claude; Aubin, Sylviane; Chrétien, Mario; Larochelle, Marie; Beaulieu, Luc

    2008-05-01

    Total body irradiation (TBI) is an efficient part of the treatment for malignant hematological diseases. Dynamic TBI techniques provide great advantages (e.g., dose homogeneity, patient comfort) while overcoming treatment room space restrictions. However, with dynamic techniques come additional organs at risk (OAR) protection challenges. In most dynamic TBI techniques, lead attenuators are used to diminish the dose received by the OARs. The purpose of this study was to characterize the dose deposition under various shapes of attenuators in static and dynamic treatments. This characterization allows for the development of a correction method to improve attenuator design in dynamic treatments. The dose deposition under attenuators at different depths in dynamic treatment was compared with the static situation based on two definitions: the coverage areas and the penumbra regions. The coverage area decreases with depth in dynamic treatment while it is stable for the static situation. The penumbra increases with depth in both treatment modes, but the increasing rate is higher in the dynamic situation. Since the attenuator coverage is deficient in the dynamic treatment mode, a correction method was developed to modify the attenuator design in order to improve the OAR protection. The correction method is divided in two steps. The first step is based on the use of elongation charts, which provide appropriate attenuator coverage and acceptable penumbra for a specific depth. The second point is a correction method for the thoracic inclination, which can introduce an orientation problem in both static and dynamic treatments. This two steps correction method is simple to use and personalized to each patient's anatomy. It can easily be adapted to any dynamic TBI techniques.

  13. Quo Vadis total reflection X-ray fluorescence?

    NASA Astrophysics Data System (ADS)

    Pahlke, Siegfried

    2003-12-01

    The multielement trace analytical method 'total reflection X-ray fluorescence' (TXRF) has become a successfully established method in the semiconductor industry, particularly, in the ultra trace element analysis of silicon wafer surfaces. TXRF applications can fulfill general industrial requirements on daily routine of monitoring wafer cleanliness up to 300 mm diameter under cleanroom conditions. Nowadays, TXRF and hyphenated TXRF methods such as 'vapor phase decomposition (VPD)-TXRF', i.e. TXRF with a preceding surface and acid digestion and preconcentration procedure, are automated routine techniques ('wafer surface preparation system', WSPS). A linear range from 10 8 to 10 14 [atoms/cm 2] for some elements is regularly controlled. Instrument uptime is higher than 90%. The method is not tedious and can automatically be operated for 24 h/7 days. Elements such as S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sn, Sb, Ba and Pb are included in the software for standard peak search. The detection limits of recovered elements are between 1×10 11 and 1×10 7 [atoms/cm 2] depending upon X-ray excitation energy and the element of interest. For the determination of low Z elements, i.e. Na, Al and Mg, TXRF has also been extended but its implementation for routine analysis needs further research. At present, VPD-TXRF determination of light elements is viable in a range of 10 9 [atoms/cm 2]. Novel detectors such as silicon drift detectors (SDD) with an active area of 5 mm 2, 10 mm 2 or 20 mm 2, respectively, and multi-array detectors forming up to 70 mm 2 are commercially available. The first SDD with 100 mm 2 (!) area and integrated backside FET is working under laboratory conditions. Applications of and comparison with ICP-MS, HR-ICP-MS and SR-TXRF, an extension of TXRF capabilities with an extremely powerful energy source, are also reported.

  14. Total internal reflection and dynamic light scattering microscopy of gels

    NASA Astrophysics Data System (ADS)

    Gregor, Brian F.

    Two different techniques which apply optical microscopy in novel ways to the study of biological systems and materials were built and applied to several samples. The first is a system for adapting the well-known technique of dynamic light scattering (DLS) to an optical microscope. This can detect and scatter light from very small volumes, as compared to standard DLS which studies light scattering from volumes 1000x larger. The small scattering volume also allows for the observation of nonergodic dynamics in appropriate samples. Porcine gastric mucin (PGM) forms a gel at low pH which lines the epithelial cell layer and acts as a protective barrier against the acidic stomach environment. The dynamics and microscopic viscosity of PGM at different pH levels is studied using polystyrene microspheres as tracer particles. The microscopic viscosity and microrheological properties of the commercial basement membrane Matrigel are also studied with this instrument. Matrigel is frequently used to culture cells and its properties remain poorly determined. Well-characterized and purely synthetic Matrigel substitutes will need to have the correct rheological and morphological characteristics. The second instrument designed and built is a microscope which uses an interferometry technique to achieve an improvement in resolution 2.5x better in one dimension than the Abbe diffraction limit. The technique is based upon the interference of the evanescent field generated on the surface of a prism by a laser in a total internal reflection geometry. The enhanced resolution is demonstrated with fluorescent samples. Additionally. Raman imaging microscopy is demonstrated using the evanescent field in resonant and non-resonant samples, although attempts at applying the enhanced resolution technique to the Raman images were ultimately unsuccessful. Applications of this instrument include high resolution imaging of cell membranes and macroscopic structures in gels and proteins. Finally, a third

  15. Investigation of the influence of reflection on the attenuation of cancellous bone.

    PubMed

    Klinge, Sandra; Hackl, Klaus; Gilbert, Robert P

    2013-01-01

    The model proposed in this paper is based on the fact that the reflection might have a significant contribution to the attenuation of the acoustic waves propagating through the cancellous bone. The numerical implementation of the mentioned effect is realized by the development of a new representative volume element that includes an infinitesimally thin 'transient' layer on the contact surface of the bone and the marrow. This layer serves to model the amplitude transformation of the incident wave by the transition through media with different acoustic impedances and to take into account the energy loss due to the reflection. The proposed representative volume element together with the multiscale finite element is used to simulate the wave propagation and to evaluate the attenuation coefficient for samples with different effective densities in the dependence of the applied excitation frequency. The obtained numerical values show a very good agreement with the experimental results. Moreover, the model enables the determination of the upper and the lower bound for the attenuation coefficient.

  16. Exploiting total internal reflection geometry for efficient optical modulation of terahertz light

    NASA Astrophysics Data System (ADS)

    Liu, Xudong; Parrott, Edward P. J.; Ung, Benjamin S.-Y.; Pickwell-MacPherson, Emma

    2016-10-01

    Efficient methods to modulate terahertz (THz) light are essential for realizing rapid THz imaging and communication applications. Here we report a novel THz modulator which utilizes the evanescent wave in a total internal reflection setup coupled with a conductive interface to enhance the attenuation efficiency of THz light. This approach makes it possible to achieve close to 100% modulation with a small interface conductivity of 12 mS. The frequency dependence of this technique is linked to the optical properties of the materials: a material with close to frequency independent conductivity that is also controllable will result in an achromatic modulation response, and the device performance can be optimized further by tuning the internal reflection angle. In this work, we focus on applying the technique in the terahertz frequency range. Using an LED array with a pump intensity of 475 mW/cm2 to produce carriers in a silicon wafer, we have achieved a modulation depth of up to 99.9% in a broad frequency range of 0.1 THz-0.8 THz. The required pumping power for the generation of the required free carriers is low because the sheet conductivity needed is far less than required for traditional transmission techniques. Consequently, the device can be modulated by an LED making it a very practical, low cost, and scalable solution for THz modulation.

  17. Teleseismic attenuation, time delays, and raypath bending, and local reflected phases at Uturuncu volcano, Bolivia

    NASA Astrophysics Data System (ADS)

    Farrell, A. K.; McNutt, S. R.

    2016-12-01

    A set of 13 teleseismic earthquakes sourced to the NW (4, Japan Subduction Zone), SE (5, South Sandwich Subduction Zone), and SW (4, Kermadec-Tonga Subduction Zones) was studied to determine how wave propagation was affected by a presumed magma body beneath Uturuncu. The number of events is small but the events have good signal-to-noise ratios and very similar waveforms for each event so that reliable measurements could be made of arrival times and amplitudes. Attenuation of amplitudes occurs in a NW-SE trend beneath the volcano, 14 by 33 km, with calculated values of quality factor Qas low as 1.7, suggesting strong seismic attenuation. Relative time delays (between the theoretical and observed travel times) of up to 0.8 sec were also observed. The pattern of attenuation and relative time delays together showed four trends: fast and not attenuated (normal crust), slow and attenuated (partial melt), fast and attenuated (likely high fracture density), and slow but not attenuated (possible deep low Vp structure). Results suggest partial melt as high as 16-60% in a region of low Bouguer gravity, high Vp/Vs, persistent seismicity, and overlapping a locus of uplift. Realistically, percent partial melt values above 30% are unlikely and therefore, to account for this, the anomaly would need to have a greater thickness along the raypath for the stations showing 30% or more, thus giving a mean partial melt zone thickness of 24.7 km for an assumed uniform percent partial melt value of 20%. Additionally, there is evidence of reflected phases from some local earthquakes interacting with the top of the mid-crustal magma body. These can be used to reduce depth uncertainty in earthquake locations as well as to determine parameters of the magma body itself, such as determining whether the contact with the country rock is sharp or gradual, resolving the presence and direction of anisotropy, and estimating whether the surface of the magma body is flat or irregular.

  18. Transmission, attenuation and reflection of shear waves in the human brain.

    PubMed

    Clayton, Erik H; Genin, Guy M; Bayly, Philip V

    2012-11-07

    Traumatic brain injuries (TBIs) are caused by acceleration of the skull or exposure to explosive blast, but the processes by which mechanical loads lead to neurological injury remain poorly understood. We adapted motion-sensitive magnetic resonance imaging methods to measure the motion of the human brain in vivo as the skull was exposed to harmonic pressure excitation (45, 60 and 80 Hz). We analysed displacement fields to quantify the transmission, attenuation and reflection of distortional (shear) waves as well as viscoelastic material properties. Results suggest that internal membranes, such as the falx cerebri and the tentorium cerebelli, play a key role in reflecting and focusing shear waves within the brain. The skull acts as a low-pass filter over the range of frequencies studied. Transmissibility of pressure waves through the skull decreases and shear wave attenuation increases with increasing frequency. The skull and brain function mechanically as an integral structure that insulates internal anatomic features; these results are valuable for building and validating mathematical models of this complex and important structural system.

  19. Transmission, attenuation and reflection of shear waves in the human brain

    PubMed Central

    Clayton, Erik H.; Genin, Guy M.; Bayly, Philip V.

    2012-01-01

    Traumatic brain injuries (TBIs) are caused by acceleration of the skull or exposure to explosive blast, but the processes by which mechanical loads lead to neurological injury remain poorly understood. We adapted motion-sensitive magnetic resonance imaging methods to measure the motion of the human brain in vivo as the skull was exposed to harmonic pressure excitation (45, 60 and 80 Hz). We analysed displacement fields to quantify the transmission, attenuation and reflection of distortional (shear) waves as well as viscoelastic material properties. Results suggest that internal membranes, such as the falx cerebri and the tentorium cerebelli, play a key role in reflecting and focusing shear waves within the brain. The skull acts as a low-pass filter over the range of frequencies studied. Transmissibility of pressure waves through the skull decreases and shear wave attenuation increases with increasing frequency. The skull and brain function mechanically as an integral structure that insulates internal anatomic features; these results are valuable for building and validating mathematical models of this complex and important structural system. PMID:22675163

  20. Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions

    SciTech Connect

    Walker, Rachel L.; Searles, Keith; Willard, Jesse A.; Michelsen, Rebecca R. H.

    2013-12-28

    Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphology allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.

  1. Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions

    NASA Astrophysics Data System (ADS)

    Walker, Rachel L.; Searles, Keith; Willard, Jesse A.; Michelsen, Rebecca R. H.

    2013-12-01

    Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphology allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.

  2. Estimating the total ultrasound attenuation along the propagation path by using a reference phantom.

    PubMed

    Labyed, Yassin; Bigelow, Timothy A

    2010-11-01

    In this study, an algorithm previously developed for estimating the total ultrasonic attenuation along the propagation path from the surface of the transducer to a region of interest (ROI) in tissue, was modified to make it more practical for use in clinical settings. Specifically, the algorithm was re-derived for when a tissue mimicking phantom rather than a planar reflector is used to obtain the reference power spectrum. The reference power spectrum is needed to compensate for the transfer function of the transmitted pulse, the transfer function of transducer, and the diffraction effects that result from focusing/beam forming. The modified algorithm was tested on simulated radio frequency (RF) echo lines obtained from two samples that have different scatterer sizes and different attenuation coefficient slopes, one of which was used as a reference. The mean and standard deviation of the percent errors in the attenuation coefficient estimates (ACEs) were less than 5% and 10%, respectively, for ROIs that contain more than 10 pulse lengths and more than 25 independent echo lines. The proposed algorithm was also tested on two tissue mimicking phantoms that have attenuation coefficient slopes of 0.7 dB/cm-MHz and 0.5 dB/cm-MHz respectively, the latter being the reference phantom. When a single element spherically focused source was used, the mean and standard deviation of the percent errors in the ACEs were less than 5% and 10% respectively for windows that contain more than 10 pulse lengths and more than 17 independent echo lines. When a clinical array transducer was used, the mean and standard deviation of the percent errors in the ACEs were less than 5% and 25%, respectively, for windows that contain more than 12 pulse lengths and more than 45 independent echo lines.

  3. Total reflection of optical beams by weakly oscillating dielectric scatterers

    NASA Astrophysics Data System (ADS)

    Granot, Er'el

    2016-12-01

    It is well known that in quantum mechanics a weak scatterer can act as a perfect reflector provided it oscillates at a specific frequency, which is close to that of the incident particles. This is a Fano resonance, in which case the propagating wave mode destructively interferes with the bound state. Due to the high frequencies of the optical domain, it is not possible to design an optical device, which is based on this effect. However, if the beam propagates in a narrow waveguide with conducting boundaries, then even a weak dielectric scatterer, which oscillates at the frequency difference between the optical frequency and the threshold frequency of the waveguide, can block the optical beam. This frequency difference can be arbitrarily small. A model for such a system is presented and solved exactly numerically without approximations. For a weak scatterer an approximate analytical expression is suggested for the point of perfect reflection. Finally, a physical realization is suggested. This effect can be used for controlling optical beams by submicron devices.

  4. Total reflection X-ray photoelectron spectroscopy as a semiconductor lubricant elemental analysis method

    NASA Astrophysics Data System (ADS)

    Alshehabi, Abbas; Sasaki, Nobuharu; Kawai, Jun

    2015-12-01

    Photoelectron spectra from a typical hard disk storage media device (HDD) were measured at total reflection and non-total reflection at unburnished, acetone-cleaned, and argon-sputtered conditions. F, O, N, and C usually making the upper layer of a typical hard disk medium were detected. Enhancement of the photoelectron emission of the fluorocarbon lubricant was observed at total reflection. Pt and Co were only found by non-total X-ray photoelectron spectroscopy (XPS) because they are constituents of a deeper region than the top and interface regions. Argon-sputtered, ultrasonic acetone-cleaned, and unburnished top layers were compared at total and non-total reflection conditions. Total reflection X-ray photoelectron spectroscopy (TRXPS) is demonstrated to be a powerful tool for storage media lubrication layer chemical state analysis, reliable for industrial quality control application , and reproducible.

  5. Total attenuation coefficient of intralipid dilutions for discrete laser wavelengths between 405 and 1315 nm

    NASA Astrophysics Data System (ADS)

    Dreischuh, Tanja N.; Gurdev, Ljuan L.; Vankov, Orlin I.; Avramov, Lachezar A.; Stoyanov, Dimitar V.

    2015-01-01

    The experimental investigations on different aspects of optical tomography require the knowledge of the optical parameters of tissues and tissue-like phantoms in order to unambiguously interpret the experimental data and specify characteristic inhomogeneities in tissue diagnostics. The main optical parameters of interest are the absorption coefficient, the scattering, backscattering, and reduced-scattering coefficients, the total attenuation (extinction) coefficient and the anisotropy factor. In this work, we extend our investigations of the optical properties of tissuemimicking phantoms, such as Intralipid-20% fat emulsion, using an approach we have developed recently based on the peculiarities of laser radiation beams propagating through semi-infinite turbid media. The dependence of the total attenuation coefficient on the Intralipid concentration, for laser radiation wavelengths λ=405, 672, 850, and 1314 nm, is studied, by using a set of phantoms consisting of different dilutions of Intralipid in distilled water. The experimental results for the extinction are in agreement with our previous results and with empiric formulae found by other authors concerning the wavelength dependence of the scattering coefficient of Intralipid -10% and Intralipid - 20%. They are also in agreement with known data of the water absorptance. As a whole, the results obtained in this work confirm the consideration of the experimental phantoms as semi-infinite media. They also confirm and extend theoretical and experimental results obtained previously, and reveal advantages of using longer wavelengths for deeper diagnostics of tissues and mimic turbid media.

  6. Incoherent broadband cavity-enhanced total internal reflection spectroscopy of surface-adsorbed metallo-porphyrins.

    PubMed

    Ruth, Albert A; Lynch, Kieran T

    2008-12-21

    An improvement of conventional attenuated total reflection (ATR) spectroscopy is demonstrated by applying an incoherent broadband light source (short-arc Xe-lamp) in a cavity-enhanced evanescent-wave absorption method. With this novel approach the absorption spectra of several metallo-octaethyl porphyrins (palladium (PdOEP), platinum (PtOEP) and zinc (ZnOEP)) in thin acetone solution layers and on a fused silica (FS) surface are studied between approximately 390 and 625 nm. The time dependence of the evaporation process of the solution on the FS surface is described. The maximum sensitivity of the setup is estimated at approximately 2 x 10(-5) per pass, which translates into a minimal detectable surface density of less than 2 x 10(-3) monolayers for the porphyrins studied (based on the strong absorption in the Soret bands). Changes of surface and solution spectra are characterised and discussed on the basis of observed band broadenings and spectral shifts. For Pd- and PtOEP the changes of spectral feature can be interpreted with respect to J-aggregate formation supported by polarization dependent measurements. The reason for an observed blue-shift of ca. 10 nm for the Soret band in ZnOEP in combination with a large red-shift of the Q-bands (11 nm for Q1 and 18 nm for Q2) is discussed.

  7. Incoherent broadband cavity-enhanced total internal reflection spectroscopy of surface-adsorbed metallo-porphyrins

    NASA Astrophysics Data System (ADS)

    Ruth, A. A.; Glaczynski, G.; Lynch, K. T.

    2009-04-01

    An improvement of conventional attenuated total reflection (ATR) spectroscopy is demonstrated by applying an incoherent broadband light source (short-arc Xe-lamp) in a cavity-enhanced evanescent-wave absorption method. With this novel approach the absorption spectra of several metallo-octaethyl porphyrins (Palladium (PdOEP), Platinum (PtOEP) and Zinc- (ZnOEP)) in thin acetone solution layers and on a fused silica (FS) surface were studied between 390 and 625 nm. The time dependence of the evaporation process of the solution on the FS surface is described. The maximum sensitivity of the setup is estimated at approximately 2 Ã- 10-5 per pass, which translates into a minimal detectable surface density of less than 2 Ã- 10-3 monolayers for the porphyrins studied (based on absorption in the strong Soret bands). Changes of surface and solution spectra are characterised and discussed on basis of observed band broadenings and spectral shifts. This new approach is of relevance for investigations in atmopsheric and planetary sciences involving absorbers on surfaces and heterogeneous chemistry.

  8. Attenuating initial beliefs: increasing the acceptance of anthropogenic climate change information by reflecting on values.

    PubMed

    van Prooijen, Anne-Marie; Sparks, Paul

    2014-05-01

    Anthropogenic climate change information tends to be interpreted against the backdrop of initial environmental beliefs, which can lead to some people being resistant toward the information. In this article (N = 88), we examined whether self-affirmation via reflection on personally important values could attenuate the impact of initial beliefs on the acceptance of anthropogenic climate change evidence. Our findings showed that initial beliefs about the human impact on ecological stability influenced the acceptance of information only among nonaffirmed participants. Self-affirmed participants who were initially resistant toward the information showed stronger beliefs in the existence of climate change risks and greater acknowledgment that individual efficacy has a role to play in reducing climate change risks than did their nonaffirmed counterparts. © 2013 Society for Risk Analysis.

  9. Determination of optical parameters of pulp suspensions by time-resolved detection of photoacoustic signals and total diffuse reflectance measurements

    NASA Astrophysics Data System (ADS)

    Zhao, Zuomin; Törmänen, Matti; Myllylä, Risto

    2010-04-01

    Time-resolved photoacoustics were used to measure the optical parameters of pulp suspensions for the first time. Reconstructing stress distribution along the direction of the incident laser light allows the effective attenuation coefficient of these suspensions to be determined. Simultaneously, the total diffuse reflectance of the suspensions was measured by the same laser source. Based on the effective attenuation coefficient and total diffuse reflectance, the absorption and reduced scattering coefficients of pulp suspensions can be calculated. In this study, three kinds of pulp suspensions with different kappa number (2, 13, and 16), a measure of lignin content in pulp fibers, were diluted with water to make samples with a consistency range from 1% to 5%, and studied at 355 nm wavelength. The results showed that the optical coefficients were approximately proportional to pulp consistency; on the other hand, the absorption coefficient was linearly correlated with kappa number, but the reduced scattering coefficient was not. Therefore, by determining its optical parameters, it is possible to extract the consistency and kappa number of an unknown pulp suspension.

  10. Effective atomic numbers and mass attenuation coefficients of some thermoluminescent dosimetric compounds for total photon interaction

    SciTech Connect

    Shivaramu; Amutha, R.; Ramprasath, V.

    1999-05-01

    Effective atomic numbers for total gamma-ray interaction with some selected thermoluminescent dosimetric compounds such as barium acetate, barium sulfate, calcium carbonate, calcium sulfate, calcium sulfate dihydrate, cadmium sulfate (anhydrous), cadmium sulfate, strontium sulfate, and lithium fluoride have been calculated in the 1-keV to 20-MeV energy region. Experimental mass attenuation coefficients and effective atomic numbers for these compounds at selected photon energies of 26.3, 33.2, 59.54, and 661.6 keV have been obtained from good geometry transmission measurements and compared with theoretical values. The effect of absorption edge on effective atomic numbers and its variation with energy, and nonvalidity of the Bragg`s mixture rule at incident photon energies closer to the absorption edges of constituent elements of compounds are discussed.

  11. Attenuation of postmenopausal bone loss in patients with transient hypoparathyroidism after total thyroidectomy.

    PubMed

    Takamura, Yuuki; Miyauchi, Akira; Yabuta, Tomonori; Kihara, Minoru; Ito, Yasuhiro; Miya, Akihiro

    2013-12-01

    Increased bone mineral density (BMD) has been reported in patients with postsurgical permanent hypoparathyroidism. Hypoparathyroidism may attenuate the high-turnover bone loss in postmenopausal women. We reported previously that patients who had transient hypoparathyroidism postoperatively were at subclinical hypoparathyroid (hP) status even 5 years after surgery. We hypothesized that patients with transient hypoparathyroidism (ThP) may have altered BMD. A total of 140 women who underwent total thyroidectomy had BMD measurements of the lumbar spine, femoral neck, and radius 3 years after surgery. At surgery, 99 patients were ≥50 years and 41 were <50 years. They were divided into three groups according to their postoperative parathyroid function: There were 80 patients in the no hP (NhP) group, 54 in the ThP group, and 6 in the permanent hP (PhP) group. Among the 99 patients aged ≥50 years, 36 ThP patients had median Z scores of the BMD in all three areas (lumbar spine, femoral neck, radius) that were significantly higher (by 1.083, 0.533, and 1.047, respectively) than those in the 60 NhP patients aged ≥50 years. The BMDs in the three PhP patients ≥50 years were higher than those in the NhP and ThP patients, but the difference did not reach significance except for in the femoral neck. Multivariate logistic regression analyses showed that Z scores > 0 were significantly associated only with the presence of ThP postoperatively. In the patients <50 years, the BMD values were not significantly different among the three groups except at the radius in PhP patients, which was significantly lower than those of the other patients. We found that ThP was associated with increased BMD in postmenopausal women. This may be due to attenuation of the high-turnover bone loss in postmenopausal women.

  12. Angular dependence of the reflectance from an isotropic polydomain medium: effect of large domain size on total reflection.

    PubMed

    Mayerhöfer, Thomas G; Popp, Jürgen

    2005-03-01

    We investigate the angular dependence of the reflectance from an isotropic medium consisting of optically large and anisotropic, randomly oriented domains, assuming a highly refractive, isotropic, and homogeneous incidence medium, which is presumed to have a higher refractive index than any of the domains' principal indices of refraction. By employing average reflectance and transmittance theory, we are able to show that the onset of total reflection is considerably shifted to higher angles of incidence compared with an isotropic medium with domains that are small compared with the wavelength. The onset of total reflection for a random medium with large domains is found to be dependent only on the largest principal index of refraction of the domains, assuming that all domains have the same optical properties. Therefore the shift of the onset depends on the magnitude of the optical anisotropy of the domains. Even in the case of a small optical anisotropy, large cross-polarization terms are predicted in the vicinity of the onset of total reflection. These terms show a pronounced maximum near that onset and extend beyond it.

  13. Retrieval of diffuse attenuation coefficient in the China seas from surface reflectance.

    PubMed

    Qiu, Zhongfeng; Wu, Tingting; Su, Yuanyuan

    2013-07-01

    Accurate estimation of the diffuse attenuation coefficient is important for our understanding the availability of light to underwater communities, which provide critical information for the China seas ecosystem. However, algorithm developments and validations of the diffuse attenuation coefficient in the China seas have been seldom performed before and therefore our knowledge on the quality of retrieval of the diffuse attenuate coefficient is poor. In this paper optical data at 306 sites collected in coastal waters of the China seas between July 2000 and February 2004 are used to evaluate three typical existing Kd(490) models. The in situ Kd(490) varied greatly among different sites from 0.029 m(-1) to 10.3 m(-1), with a mean of 0.92 ± 1.59 m(-1). Results show that the empirical model and the semi-analytical model significantly underestimate the Kd(490) value, with estimated mean values of 0.24 m(-1) and 0.5 m(-1), respectively. The combined model also shows significant differences when the in situ Kd(490) range from 0.2 m(-1) to 1 m(-1). Thus, the present study proposes that the three algorithms cannot be directly used to appropriately estimate Kd(490) in the turbid coastal waters of the China seas without a fine tuning for regional applications. In this paper, new Kd(490) algorithms are developed based on the semi-analytical retrieval of the absorption coefficient a(m(-1)) and the backscattering coefficient bb(m(-1)) from the reflectance at two wavelengths, 488 and 667 nm for the Moderate Resolution Imaging Spectroradiometer (MODIS) and 490 and 705 nm for the Medium Resolution Imaging Spectrometer (MERIS) applications, respectively. With the new approaches, the mean ratio and the relative percentage difference are 1.05 and 4.6%, respectively, based on an independent in situ data set. Furthermore, the estimates are reliable within a factor of 1.9 (95% confidence interval). Comparisons also show that the Kd(490) derived with the new algorithms are well correlated

  14. Intensification of acoustic beams in crystals at mode conversion near total internal reflection

    NASA Astrophysics Data System (ADS)

    Alshits, V. I.; Bessonov, D. A.; Lyubimov, V. N.

    2017-07-01

    Geometrical conditions under which mode conversion occurs in a crystal near total internal reflection of an acoustic beam are found. In this case, the entire energy of an incident pump wave is spent on the excitation of a narrow intense reflected beam close in structure to an eigenmode. A consistent choice of orientations of the sagittal plane and surface that excludes the reflection of a parasitic wave of leakage is found.

  15. Amplitude Variation of Bottom Simulating Reflection with Respect to Frequency - Transitional Base or Attenuation?

    USGS Publications Warehouse

    Lee, Myung W.

    2007-01-01

    The amplitude of a bottom simulating reflection (BSR), which occurs near the phase boundary between gas hydrate-bearing sediments and underlying gas-filled sediments, strongly depends on the frequency content of a seismic signal, as well as the impedance contrast across the phase boundary. A strong-amplitude BSR, detectable in a conventional seismic profile, is a good indicator of the presence of free gas beneath the phase boundary. However, the BSR as observed in low-frequency multichannel seismic data is generally difficult to identify in high-frequency, single-channel seismic data. To investigate the frequency dependence of BSR amplitudes, single-channel seismic data acquired with an air gun source at Blake Ridge, which is located off the shore of South Carolina, were analyzed in the frequency range of 10-240 Hz. The frequency-dependent impedance contrast caused by the velocity dispersion in partially gas saturated sediments is important to accurately analyze BSR amplitude. Analysis indicates that seismic attenuation of gas hydrate-bearing sediments, velocity dispersion, and a transitional base all contribute to the frequency-dependent BSR amplitude variation in the frequency range of 10-500 Hz. When velocity dispersion is incorporated into the BSR amplitude analysis, the frequency-dependent BSR amplitude at Blake Ridge can be explained with gas hydrate-bearing sediments having a quality factor of about 250 and a transitional base with a thickness of about 1 meter.

  16. Forensic application of total reflection X-ray fluorescence spectrometry for elemental characterization of ink samples

    NASA Astrophysics Data System (ADS)

    Dhara, Sangita; Misra, N. L.; Maind, S. D.; Kumar, Sanjukta A.; Chattopadhyay, N.; Aggarwal, S. K.

    2010-02-01

    The possibility of applying Total Reflection X-ray Fluorescence for qualitative and quantitative differentiation of documents printed with rare earth tagged and untagged inks has been explored in this paper. For qualitative differentiation, a very small amount of ink was loosened from the printed documents by smoothly rubbing with a new clean blade without destroying the manuscript. 50 μL of Milli-Q water was put on this loose powder, on the manuscript, and was agitated by sucking and releasing the suspension two to three times with the help of a micropipette. The resultant dispersion was deposited on quartz sample support for Total Reflection X-ray Fluorescence measurements. The Total Reflection X-ray Fluorescence spectrum of tagged and untagged inks could be clearly differentiated. In order to see the applicability of Total Reflection X-ray Fluorescence for quantitative determinations of rare earths and also to countercheck such determinations in ink samples, the amounts of rare earth in painted papers with single rare earth tagged inks were determined by digesting the painted paper in HNO 3/HClO 4, mixing this solution with the internal standard and recording their Total Reflection X-ray Fluorescence spectra after calibration of the instrument. The results thus obtained were compared with those obtained by Inductively Coupled Plasma Mass Spectrometry and were found in good agreement. The average precision of the Total Reflection X-ray Fluorescence determinations was 5.5% (1 σ) and the average deviation of Total Reflection X-ray Fluorescence determined values with that of Inductively Coupled Plasma Mass Spectrometry was 7.3%. These studies have shown that Total Reflection X-ray Fluorescence offers a promising and potential application in forensic work of this nature.

  17. A method based on reflection theory to test the attenuation performance of an absorption coat to 8mm waves

    NASA Astrophysics Data System (ADS)

    Wang, Xuanyu

    2016-09-01

    A testing method has been set up to evaluate the attenuation performance of an absorption coat to 8mm waves, which is based on a set of detecting system included by an 8mm wave emitter, a millimeter power meter, a point to point collimator and a reflecting plate. The power meter was aimed at the 8 mm wave emitter along the reflection optical path instead of the direction observation between incident and reflected millimeter wave. Some Al, Fe and aluminum alloy sample plates were made and painted by the dope which was complexed with chopped carbon fibers. A naked metal plate was first used to adjust the transmission path of the millimeter wave. Then the power meter was adjusted to phase locking after preheating, and the millimeter wave power was sampled as the background value. Then the other painted plates were tested under the same conditions. When the concentration of chopped carbon fibers is 0.5mg/ml and the thickness of the absorption coat is 0.5mm, the attenuation percentages of Al, Fe and aluminum alloy painted plates respectively is 54.29%, 58.31% and 41.12%. By the result, the reflection testing method may be widely used to measure the reflection capacity or attenuation performance of various surfaces to millimeter waves.

  18. Total transmission and total reflection of acoustic wave by zero index metamaterials loaded with general solid defects

    NASA Astrophysics Data System (ADS)

    Wang, Ziyu; Yang, Fan; Liu, LiBing; Kang, Ming; Liu, Fengming

    2013-11-01

    This work investigates acoustic wave transmission property through a zero index metamaterials (ZIM) waveguide embedded with a general solid defect. Total transmission and total reflection can be achieved by adjusting the parameters of the solid defect. We comprehensively study how longitudinal/transverse wave speeds of the solid defect affect the acoustic wave propagation through the waveguide. A two-dimensional (2D) acoustic crystals system with zero index is used to realize these intriguing transmission properties. Thus, our work provides more possibilities to manipulate acoustic wave propagation through ZIM.

  19. Quantitative total and diffuse reflectance laboratory measurements for remote, standoff, and point sensing

    NASA Astrophysics Data System (ADS)

    Blake, Thomas A.; Johnson, Timothy J.; Tonkyn, Russell G.; Forland, Brenda M.; Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong

    2014-05-01

    Methods for making total and diffuse directional/hemispherical reflectance measurements in the shortwave to longwave infrared using an integrating sphere are described. The sphere is a commercial, off-the-shelf optical device with its sample port at the bottom, which is essential for examining powdered samples without using a cover glass. The reflectance spectra of recently-developed National Institute of Standards and Technology (NIST, USA) infrared reflectance standards have been measured using the sphere. Reflectance spectra of other materials such as Spectralon and Infragold were also measured. The relative systematic error for the total reflectance measurements is estimated to be on the order of 3%, and random measurement error for multiple samples of each material is on the order of 0.5%.

  20. Quantitative Total and Diffuse Reflectance Laboratory Measurements for Remote, Standoff, and Point Sensing

    SciTech Connect

    Blake, Thomas A.; Johnson, Timothy J.; Tonkyn, Russell G.; Forland, Brenda M.; Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong

    2014-06-10

    Methods for making total and diffuse directional/hemispherical reflectance measurements in the shortwave to longwave infrared using an integrating sphere are described. The sphere is a commercial, off-the-shelf optical device with its sample port at the bottom, which is essential for examining powdered samples without using a cover glass. The reflectance spectra of recently-developed National Institute of Standards and Technology (NIST, USA) infrared reflectance standards have been measured using the sphere. Reflectance spectra of other materials such as Spectralon and Infragold were also measured. The relative systematic error for the total reflectance measurements is estimated to be on the order of 3%, and random measurement error for multiple samples of each material is on the order of 0.5%.

  1. Reflective variable optical attenuators and fibre ring lasers for wavelength-division multiplexing systems

    NASA Astrophysics Data System (ADS)

    Liu, He Liang

    Wavelength division multiplexing (WDM) optical fibre system is an important enabling technology to fulfill the demands for bandwidth in the modern information age. The main objective of this project is to study novel devices with the potential to enhance the performance of WDM systems. In particular, a novel reflective variable optical attenuator (RVOA) used for dynamic gain equalization (DGE) and fibre lasers based on an entirely new type of erbium-doped fibres with ultrawide tuning range were investigated theoretically and experimentally. We proposed a new type of RVOA device which could be potentially integrated with arrayed waveguide grating (AWG) to reduce the cost of DGE substantially. Initially, fibre-based RVOAs, fabricated with optical fibre components such as fibre coupler and Faraday rotator mirror, were investigated theoretically and experimentally. Larger attenuation range up to 22 dB was realized for fibre coupler-based ROVA with a Faraday rotator mirror and its polarization-dependent loss is about 0.5 dB. Then polymeric waveguide-based RVOAs were investigated theoretically and experimentally. Using an epoxy Novolak resin as core material and an UV-cured resin (Norland's NOA61) as cladding material, a polymeric waveguide RVOA was successfully fabricated. The dynamic 15 dB attenuation range was achieved and the PDL was less than 0.2 dB. The measured insertion loss of the polymeric waveguide RVOA was too large (about 18 dB) and was mainly induced by coupling loss, material loss and poor alignment. In the second part of the study, fibre ring lasers with continuous wavelength tuning over wide wavelength range and fibre ring lasers with discrete wavelength tuning were investigated. Tunable lasers are important devices in WDM systems because they could be employed as reserved sources and therefore avoiding the need to stock large inventory of lasers to cover the ITU-wavelength grid. In this project, erbium ions doped bismuth oxide glass fibres instead of

  2. Attenuation of fission neutrons by some hydrogeneous shield materials and the exponential dependence of the attenuated total neutron dose rate on the shield thickness.

    PubMed

    Ibrahim, M A

    2000-01-01

    This work deals with the attenuation of fission neutrons by some hydrogeneous shield materials. The attenuated fission neutrons are described by the energy groups (fast, epithermal and thermal). The exponential decrease in the fast flux is represented by the removal cross section concept. Each of the epithermal and thermal fluxes is expressed using the diffusion equation including a pair of arbitrary constants to be determined using the corresponding boundary conditions. The solution obtained for the required arbitrary constants is then approximated in a simplified form such that it may easily replace the corresponding exact solution. The attenuation values, by which the neutron dose rate distributions are exponentially decreased through certain thicknesses are also determined for the given materials. They are compared to the corresponding experimental and theoretical data. The results obtained for the total neutron dose rate distributions in terms of a suitable range of layer thicknesses are then used to determine--for each material--an average value for the total neutron dose rate representing the exponential decrease during passage through the considered range of layer thicknesses.

  3. Mapping fluorophore distributions in three dimensions by quantitative multiple angle-total internal reflection fluorescence microscopy.

    PubMed Central

    Olveczky, B P; Periasamy, N; Verkman, A S

    1997-01-01

    The decay of evanescent field intensity beyond a dielectric interface depends upon beam incident angle, enabling the 3-d distribution of fluorophores to be deduced from total internal reflection fluorescence microscopy (TIRFM) images obtained at multiple incident angles. Instrumentation was constructed for computer-automated multiple angle-TIRFM (MA-TIRFM) using a right angle F2 glass prism (n(r) 1.632) to create the dielectric interface. A laser beam (488 nm) was attenuated by an acoustooptic modulator and directed onto a specified spot on the prism surface. Beam incident angle was set using three microstepper motors controlling two rotatable mirrors and a rotatable optical flat. TIRFM images were acquired by a cooled CCD camera in approximately 0.5 degree steps for >15 incident angles starting from the critical angle. For cell studies, cells were grown directly on the glass prisms (without refractive index-matching fluid) and positioned in the optical path. Images of the samples were acquired at multiple angles, and corrected for angle-dependent evanescent field intensity using "reference" images acquired with a fluorophore solution replacing the sample. A theory was developed to compute fluorophore z-distribution by inverse Laplace transform of angle-resolved intensity functions. The theory included analysis of multiple layers of different refractive index for cell studies, and the anisotropic emission from fluorophores near a dielectric interface. Instrument performance was validated by mapping the thickness of a film of dihexyloxacarbocyanine in DMSO/water (n(r) 1.463) between the F2 glass prism and a plano-convex silica lens (458 mm radius, n(r) 1.463); the MA-TIRFM map accurately reproduced the lens spherical surface. MA-TIRFM was used to compare with nanometer z-resolution the geometry of cell-substrate contact for BCECF-labeled 3T3 fibroblasts versus MDCK epithelial cells. These studies establish MA-TIRFM for measurement of submicroscopic distances between

  4. Sulfate adsorption at the buried hematite/solution interface investigated using total internal reflection (TIR)-Raman spectroscopy.

    PubMed

    Jubb, Aaron M; Verreault, Dominique; Posner, Ralf; Criscenti, Louise J; Katz, Lynn E; Allen, Heather C

    2013-06-15

    Sulfate adsorption at buried mineral/solution interfaces is of great interest in geochemistry and atmospheric aerosol chemistry due to the sulfate anion's environmental ubiquity and the wide role of physical and chemical phenomena that it impacts. Here we present the first application of total internal reflection-Raman (TIR-Raman) spectroscopy, a surface sensitive spectroscopy, to probe sulfate ion behavior at the buried hematite/solution interface. Hematite is the most thermodynamically stable iron oxide polymorph and as such is widely found in nature. Our results demonstrate the feasibility of a TIR-Raman approach to study simple, inorganic anion adsorption at buried interfaces. Moreover, our data suggest that inner-sphere sulfate adsorption proceeds in a bidentate fashion at the hematite surface. These results help clarify long-standing questions as to whether sulfate forms inner-sphere adsorption complexes at hematite surfaces in a mono- or bidentate fashion based on attenuated total reflection-infrared (ATR-IR) observations. Our results are discussed with perspective to this debate and the applicability of TIR-Raman spectroscopy to address ambiguities of ion adsorption to mineral surfaces.

  5. Monte Carlo simulation applied in total reflection x-ray fluorescence: Preliminary results

    SciTech Connect

    Meira, Luiza L. C.; Inocente, Guilherme F.; Vieira, Leticia D.; Mesa, Joel

    2013-05-06

    The X-ray Fluorescence (XRF) analysis is a technique for the qualitative and quantitative determination of chemical constituents in a sample. This method is based on detection of the characteristic radiation intensities emitted by the elements of the sample, when properly excited. A variant of this technique is the Total Reflection X-ray Fluorescence (TXRF) that utilizes electromagnetic radiation as excitation source. In total reflection of X-ray, the angle of refraction of the incident beam tends to zero and the refracted beam is tangent to the sample support interface. Thus, there is a minimum angle of incidence at which no refracted beam exists and all incident radiation undergoes total reflection. In this study, we evaluated the influence of the energy variation of the beam of incident x-rays, using the MCNPX code (Monte Carlo NParticle) based on Monte Carlo method.

  6. Slow-light total-internal-reflection switch with bending angle of 30 deg.

    PubMed

    Fuchida, Ayumi; Matsutani, Akihiro; Koyama, Fumio

    2011-07-15

    Slowing light in a Bragg reflector waveguide is used to miniaturize optical waveguide switches. We can realize a giant equivalent refractive index change induced by carrier injection near a cutoff wavelength due to its large waveguide dispersion. We fabricate and characterize a reflection-type slow-light switch. Input light is reflected at the off state due to an equivalent index difference between an oxide aperture and an oxide region, while it passes through at the on state, since the equivalent index difference is compensated using carrier injection. We obtained a large bending angle of 30° with total internal reflection of slow light.

  7. Steady-state total diffuse reflectance with an exponential decaying source.

    PubMed

    Symvoulidis, Panagiotis; Jentoft, Karin M; Garcia-Allende, P Beatriz; Glatz, Jürgen; Ripoll, Jorge; Ntziachristos, Vasilis

    2014-07-01

    The increasing preclinical and clinical utilization of digital cameras for photographic measurements of tissue conditions motivates the study of reflectance measurements obtained with planar illumination. We examine herein a formula that models the total diffuse reflectance measured from a semi-infinite medium using an exponentially decaying source, assuming continuous plane wave epi-illumination. The model is validated with experimental reflectance measurements from tissue mimicking phantoms. The need for adjusting the blood absorption spectrum due to pigment packaging is discussed along with the potential applications of the proposed formulation.

  8. Influence of distortions on the determination of liquid crystal parameters by the attenuated total reflection technique

    NASA Astrophysics Data System (ADS)

    Eidner, K.; Mayer, G.; Schuster, R.

    1986-10-01

    Theoretical considerations and measurements on a thin plane-parallel plate show that the fringes of equal inclination and the shift of the whole interference pattern, induced by an external magnetic field, must be used for a correct determination of optical and anchoring properties of liquid crystals.

  9. Detection of Citrus Huanglongbing by Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR) Spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Citrus Huanglongbing (HLB, also known as citrus greening disease) was discovered in Florida in 2005 and is spreading rapidly amongst the citrus growing regions of the state. Detection via visual symptoms of the disease is not a long term viable option. New techniques are being developed to test fo...

  10. Attenuated total reflection infrared spectroscopy (ATR-IR) as an in situ technique for dissolution studies.

    PubMed

    Kassis, Abe; Bhawtankar, Vrushali M; Sowa, John R

    2010-11-02

    Dissolution studies are critical tests for measuring the performance of a drug product. We have developed a novel technique using in situ ATR-IR spectroscopy to monitor dissolutions of pharmaceutical drug products. The accuracy of this technique is +/-3% relative to HPLC using salicylic acid calibrator tablets and acetaminophen OTC tablets. This novel approach also gives the research laboratory the capability of analyzing individual ingredients in multiple tablets; for example, individual components of salicylic acid and acetaminophen tablets are easily distinguished. In addition, the individual ingredients of a multi-component tablet containing acetylsalicylic acid and acetaminophen are readily distinguished. The ATR-IR system was found to have good sensitivity and can analyze samples as low as 0.03 mg/ml. With improved sensitivity, this is a promising method for monitoring dissolution of pharmaceutical tablets with an excellent in situ capability for distinguishing individual components. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  11. Determination of cholesterol concentration in human milk samples using attenuated total reflectance Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kamelska, A. M.; Pietrzak-Fiećko, R.; Bryl, K.

    2013-03-01

    Results of an inexpensive and rapid evaluation of the cholesterol concentration in human milk using ATR-FTIR techniques are presented. The FTIR spectrum of pure cholesterol was characterized and quantitatively estimated in the region between 2800 and 3200 cm-1. 125 samples at different stages of lactation were analyzed. There were no differences between the cholesterol concentrations in the samples of early (1-3 months), medium (4-6 months), and late (> 6 months) lactation stages ( p = 0.096968). The cholesterol concentration ranged from 4.30 to 21.77 mg/100 cm3. Such a broad range was due to the differences between the samples from different women ( p = 0.000184). The results indicate that ATR-FTIR has potential for rapid estimation of cholesterol concentration in human milk.

  12. Rapid identification and classification of Staphylococcus aureus by attenuated total reflectance fourier transform infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Staphylococcus aureus is an important bacterium that can cause serious infections in humans such as pneumonia and bacteremia. Rapid detection of this pathogen is crucial in food industries and clinical laboratories to control S. aureus food poisoning and human infections. In this study, fourier tran...

  13. An Attenuated Total Reflectance Sensor for Copper: An Experiment for Analytical or Physical Chemistry

    ERIC Educational Resources Information Center

    Shtoyko, Tanya; Zudans, Imants; Seliskar, Carl J.; Heineman, William R.; Richardson, John N.

    2004-01-01

    A sensor experiment which can be applied to advanced undergraduate laboratory course in physical or analytical chemistry is described along with certain concepts like the demonstration of chemical sensing, preparation of thin films on a substrate, microtitration, optical determination of complex ion stoichiometry and isosbestic point. It is seen…

  14. An Attenuated Total Reflectance Sensor for Copper: An Experiment for Analytical or Physical Chemistry

    ERIC Educational Resources Information Center

    Shtoyko, Tanya; Zudans, Imants; Seliskar, Carl J.; Heineman, William R.; Richardson, John N.

    2004-01-01

    A sensor experiment which can be applied to advanced undergraduate laboratory course in physical or analytical chemistry is described along with certain concepts like the demonstration of chemical sensing, preparation of thin films on a substrate, microtitration, optical determination of complex ion stoichiometry and isosbestic point. It is seen…

  15. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic analysis of regenerated bone

    NASA Astrophysics Data System (ADS)

    Benetti, Carolina; Kazarain, Sergei G.; Alves, Marco A. V.; Blay, Alberto; Correa, Luciana; Zezell, Denise M.

    2014-03-01

    The cutting of bone is routinely required in medical procedures, especially in dental applications. In such cases, bone regeneration and new bone quality can determine the success of the treatment. This study investigated the main spectral differences of undamaged and healed bone using the ATR-FTIR spectroscopy technique. Three rabbits were submitted to a surgical procedure; a small piece of bone (3x3 mm2) was removed from both sides of their jaws using a high speed drill. After 15 days, the rabbits were euthanized and the jaws were removed. A bone slice was cut from each side of the jaw containing regions of undamaged and newly formed bone, resulting in six samples which were polished for spectroscopic comparison. The samples were analyzed by FTIR spectroscopy using a diamond ATR accessory. Spectral characteristics were compared and particular attention was paid to the proportion of phosphate to amide I bands and the width of the phosphate band. The results show that the ratio of phosphate to amide I is smaller in new bone tissue than in the undamaged bone, indicating a higher organic content in the newly formed bone. The analysis of the width of the phosphate band suggests a crystallinity difference between both tissues, since the width was higher in the new bone than in the natural bone. These results suggest that the differences observed in bone aging processes by FTIR spectroscopic can be applied to the study of healing processes.

  16. Focusing hard x rays beyond the critical angle of total reflection by adiabatically focusing lenses

    DOE PAGES

    Patommel, Jens; Klare, Susanne; Hoppe, Robert; ...

    2017-03-06

    In response to the conjecture that the numerical aperture of x-ray optics is fundamentally limited by the critical angle of total reflection, the concept of adiabatically focusing refractive lenses was proposed to overcome this limit. Here, we present an experimental realization of these optics made of silicon and demonstrate that they indeed focus 20 keV x rays to a 18.4 nm focus with a numerical aperture of 1.73(9) × 10–3 that clearly exceeds the critical angle of total reflection of 1.55 mrad.

  17. Total internal reflection resonance light scattering at solid/liquid interfaces.

    PubMed

    Tang, Yao-Ji; Chen, Ying; Yao, Min-Na; Li, Yao-Qun

    2008-08-05

    Total internal reflection (TIR) technique is an interface-specific tool and resonance light scattering (RLS) is of high sensitivity. The combination of both approaches is introduced into the solid/liquid interface for the first time. The behaviors of mixture of TPPS and BSA at the interface have been studied with total internal reflection resonance light scattering (TIR-RLS). The preliminary experimental results indicate that TIR-RLS is a good approach to study the interaction and distinguish the states of macromolecules at the solid/liquid interface.

  18. Amplified total internal reflection: theory, analysis, and demonstration of existence via FDTD.

    PubMed

    Willis, Keely J; Schneider, John B; Hagness, Susan C

    2008-02-04

    The explanation of wave behavior upon total internal reflection from a gainy medium has defied consensus for 40 years. We examine this question using both the finite-difference time-domain (FDTD) method and theoretical analyses. FDTD simulations of a localized wave impinging on a gainy half space are based directly on Maxwell's equations and make no underlying assumptions. They reveal that amplification occurs upon total internal reflection from a gainy medium; conversely, amplification does not occur for incidence below the critical angle. Excellent agreement is obtained between the FDTD results and an analytical formulation that employs a new branch cut in the complex "propagation-constant" plane.

  19. Calibration of a turbidity meter for making estimates of total suspended solids concentrations and beam attenuation coefficients in field experiments

    NASA Technical Reports Server (NTRS)

    Usry, J. W.; Whitlock, C. H.

    1981-01-01

    Management of water resources such as a reservoir requires using analytical models which describe such parameters as the suspended sediment field. To select or develop an appropriate model requires making many measurements to describe the distribution of this parameter in the water column. One potential method for making those measurements expeditiously is to measure light transmission or turbidity and relate that parameter to total suspended solids concentrations. An instrument which may be used for this purpose was calibrated by generating curves of transmission measurements plotted against measured values of total suspended solids concentrations and beam attenuation coefficients. Results of these experiments indicate that field measurements made with this instrument using curves generated in this study should correlate with total suspended solids concentrations and beam attenuation coefficients in the water column within 20 percent.

  20. Total reflection and cloaking by zero index metamaterials loaded with rectangular dielectric defects

    NASA Astrophysics Data System (ADS)

    Wu, Ying; Li, Jichun

    2013-05-01

    In this work, we investigate wave transmission property through a zero index metamaterial (ZIM) waveguide embedded with rectangular dielectric defects. We show that total reflection and total transmission (cloaking) can be achieved by adjusting the geometric sizes and/or permittivities of the defects. Our work provides another possibility of manipulating wave propagation through ZIM in addition to the widely studied dielectric defects with cylindrical geometries.

  1. Interferences with an Plane Parallel Plate Near the Critical Angel of Total Reflection

    NASA Astrophysics Data System (ADS)

    Eidner, K.; Mayer, G.; Schuster, R.

    1985-07-01

    The fringes of equal inclination with a plane parallel plate surrounded by an optically denser medium start at an angle of incidence less than the critical angle of total reflection. Despite its practical importance this effect was disregarded in optics up to now.

  2. Nondestructive Determination of Total Chlorophyll Content in Maize Using Three-Wavelength Diffuse Reflectance

    NASA Astrophysics Data System (ADS)

    Gu, D.-D.; Wang, W.-Z.; Hu, J.-D.; Zhang, X.-M.; Wang, J.-B.; Wang, B.-S.

    2016-09-01

    Chlorophyll in leaves plays a vital role in plant growth and can be used as an indicator of a plant's nutritional status. In this paper, an experimental setup for measuring total chlorophyll content using three-wavelength diffuse reflectance is proposed, for which light-emitting diodes with peak wavelengths of 640, 660, and 940 nm are used. Two different maize strains, Zhengdan-958 and Xundan-20, fertilized at different levels before the jointing stage, were used to validate this setup. Regression analyses between remission function values of diffuse reflectance and SPAD values, as well as remission function values of diffuse reflectance and the actual total chlorophyll content, were performed. The determination coefficients between remission function values and the actual total chlorophyll content were 0.9766 for Zhengdan-958 leaves and 0.9612 for Xundan-20 leaves. The experimental results validated the feasibility of using the diffuse reflectance spectrum to determine the total chlorophyll content. This paper also provides guidance for the development of a portable instrument to determine the actual chlorophyll content.

  3. Hard x-ray nanofocusing using total-reflection zone plates

    SciTech Connect

    Takano, Hidekazu Matsumura, Atsuyuki; Sakka, Kenji; Tsusaka, Yoshiyuki; Kagoshima, Yasushi; Tsuji, Takuya

    2016-01-28

    A total-reflection zone plate (TRZP), which is a reflective grating that generates a line focus of hard X-rays, was developed. Newly designed TRZPs, introducing a laminar grating concept, were fabricated with various zone parameters. The focusing performances with regard to the beam size and the diffraction efficiency were evaluated using synchrotron radiation X-rays of 10 keV energy. Although the beam sizes measured are insufficient in comparison with the ideal value, the maximum diffraction efficiency, measured at 20%, exceeds the limitations of conventional TRZPs based on a binary grating.

  4. Energy flux and Goos-Hänchen shift in frustrated total internal reflection.

    PubMed

    Chen, Xi; Lu, Xiao-Jing; Zhao, Pei-Liang; Zhu, Qi-Biao

    2012-05-01

    Using Yasumoto and Õishi's energy flux method, a generalized analytical formulation for analyzing the Goos-Hänchen (GH) shift in frustrated total internal reflection is provided, from which the GH shift given by Artman's stationary phase method is shown to equal the GH calculated by Renard's conventional energy flux method plus a self-interference shift. The self-interference shift, originating from the interference between the incident and reflected beams, sheds light on the asymptotic behavior of the GH shift in such optical tunneling process in term of energy flux.

  5. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    DOEpatents

    Pipino, Andrew Charles Rule

    1999-11-16

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  6. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    DOEpatents

    Pipino, Andrew C. R.; Hudgens, Jeffrey W.

    1999-08-24

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  7. Nanotopology of cell adhesion upon Variable-Angle Total Internal Reflection Fluorescence Microscopy (VA-TIRFM).

    PubMed

    Wagner, Michael; Weber, Petra; Baumann, Harald; Schneckenburger, Herbert

    2012-10-02

    Surface topology, e.g. of cells growing on a substrate, is determined with nanometer precision by Variable-Angle Total Internal Reflection Fluorescence Microscopy (VA-TIRFM). Cells are cultivated on transparent slides and incubated with a fluorescent marker homogeneously distributed in their plasma membrane. Illumination occurs by a parallel laser beam under variable angles of total internal reflection (TIR) with different penetration depths of the evanescent electromagnetic field. Recording of fluorescence images upon irradiation at about 10 different angles permits to calculate cell-substrate distances with a precision of a few nanometers. Differences of adhesion between various cell lines, e.g. cancer cells and less malignant cells, are thus determined. In addition, possible changes of cell adhesion upon chemical or photodynamic treatment can be examined. In comparison with other methods of super-resolution microscopy light exposure is kept very small, and no damage of living cells is expected to occur.

  8. Application of the Total Reflection X-ray Fluorescence technique to trace elements determination in tobacco

    NASA Astrophysics Data System (ADS)

    Martinez, T.; Lartigue, J.; Zarazua, G.; Avila-Perez, P.; Navarrete, M.; Tejeda, S.

    2008-12-01

    Many studies have identified an important number of toxic elements along with organic carcinogen molecules and radioactive isotopes in tobacco. In this work we have analyzed by Total Reflection X-Ray Fluorescence 9 brands of cigarettes being manufactured and distributed in the Mexican market. Two National Institute of Standards and Technology standards and a blank were equally treated at the same time. Results show the presence of some toxic elements such as Pb and Ni. These results are compared with available data for some foreign brands, while their implications for health are discussed. It can be confirmed that the Total Reflection X-Ray Fluorescence method provides precise (reproducible) and accuracy (trueness) data for 15 elements concentration in tobacco samples.

  9. Circular and near-circular polarization states of evanescent monochromatic light fields in total internal reflection.

    PubMed

    Azzam, R M A

    2011-11-20

    Conditions for the production of near-circular polarization states of the evanescent field present in the rarer medium in total internal reflection of incident monochromatic p-polarized light at a dielectric-dielectric planar interface are determined. Such conditions are satisfied if high-index (>3.2) transparent prism materials (e.g., GaP and Ge) are used at angles of incidence well above the critical angle but sufficiently below grazing incidence. Furthermore, elliptical polarization of incident light with nonzero p and s components can be tailored to cause circular polarization of the resultant tangential electric field in the plane of the interface or circular polarization of the transverse electric field in a plane normal to the direction of propagation of the evanescent wave. Such polarization control of the evanescent field is significant, e.g., in the fluorescent excitation of molecules adsorbed at solid-liquid and solid-gas interfaces by total internal reflection.

  10. Zero infrared reflectance anomaly in doped silicon lamellar gratings. I. From antireflection to total absorption

    NASA Astrophysics Data System (ADS)

    Auslender, M.; Hava, S.

    1995-12-01

    Zero-reflectance phenomenon for a binary lamellar grating on n-Si substrate irradiated by normally incident TE polarized plane electromagnetic wave of wavelength 10.6 μm is studied. The treatment is performed in the strong diffraction regime, where the structural dimensions and the wavelength are of the same order of magnitude, using data on the IR dielectric function of bulk doped silicon and a version of rigorous coupled-wave analysis. The evolution of normal reflectance zeros with increasing electron concentration from dielecric to metallic-like n-Si is traced. It is shown that the groove height undergoes sharp increase and the period shrinks when plasma wavelength becomes equal to the radiation wavelength. This marks the transition from the antireflection to the total absorption regime where most of incident power is absorbed in the grating region. The cavity-resonance origin of total absorption and satellite peaks in the spectral response are discussed.

  11. Determination of trace elements in macrozoobenthos samples by total reflection X-ray fluorescence analysis

    NASA Astrophysics Data System (ADS)

    Miesbauer, Hermann; Köck, Günter; Füreder, Leo

    2001-11-01

    The paper describes the analysis of a set of metals in macrozoobenthos samples from a river in Western Austria by using total reflection X-ray fluorescence analysis (TXRF). Metal concentrations in aquatic insect larvae from an industrially contaminated site are significantly higher than in larvae from a reference site. Furthermore, species-specific differences in metal accumulation were found. TXRF allows multi-element analysis of very low metal concentrations in very small sample masses (e.g. single aquatic insect larvae with a dry weight of only a few milligrams). Due to its multi-element capability and high sensitivity total reflection X-ray fluorescence analysis is a valuable tool for biomonitoring studies of metal contamination in aquatic ecosystems.

  12. Experimental observation of the Imbert-Fedorov transverse displacement after a single total reflection.

    PubMed

    Pillon, Frank; Gilles, Hervé; Girard, Sylvain

    2004-03-20

    We describe a simple experimental setup with which to observe the transverse shift--also known as the Imbert-Fedorov effect-that circularly or elliptically polarized optical beams undergo after a single total internal reflection on a dielectric plane. A comparison between a theoretical model based on the conservation of energy and experimental measurements shows good agreement simultaneously for longitudinal (Goos-Hänchen) and transverse (Imbert-Fedorov) displacements.

  13. Slow propagation, anomalous absorption, and total external reflection of surface plasmon polaritons in nanolayer systems.

    PubMed

    Stockman, Mark I

    2006-11-01

    I predict that a nanoscopic, high-permittivity layer on the surface of a plasmonic metal can cause total external reflection of surface plasmon polaritons (SPPs). Such a layer can be used as a mirror in nanoplasmonics, in particular for resonators of nanolasers and spasers and can also be used in adiabatic nanooptics. I also show that the earlier predicted slow propagating SPP modes, especially those with negative refraction, are highly damped.

  14. Design rule of nanostructures in light-emitting diodes for complete elimination of total internal reflection.

    PubMed

    Son, Jun Ho; Kim, Jong Uk; Song, Yang Hee; Kim, Buem Joon; Ryu, Chul Jong; Lee, Jong-Lam

    2012-05-02

    Cone-shaped nanostructures with controllable side-wall angle are success- fully fabricated with a SiO(2) nanosphere lithography (NSL) etching mask. Vertical LEDs with cone-shaped nanostructures with a 24.1° side-wall angle provide 6% more light output power compared to those using hexagonal pyramids formed by photochemical etching. This achievement is attributed to effective elimination of total internal reflection by angle-controlled nanostructures.

  15. Dielectric compound parabolic concentrating solar collector with a frustrated total internal reflection absorber.

    PubMed

    Hull, J R

    1989-01-01

    Coupling a dielectric compound parabolic concentrator (DCPC) to an absorber across a vacuum gap by means of frustrated total internal reflection (FTIR) can theoretically approach the maximum concentration permitted by physical laws, thus allowing higher radiative fluxes in thermal applications. The calculated optical performance of 2-D DCPCs with FTIR absorbers indicates that the ratio of gap thickness to optical wavelength must be <0.22 before the optical performance of the DCPC is superior to that of the nondielectric CPC.

  16. Silica colloidal crystals as porous substrates for total internal reflection fluorescence microscopy of live cells.

    PubMed

    Velarde, Tomika R C; Wirth, Mary J

    2008-06-01

    Total internal reflection fluorescence (TIRF) microscopy is a powerful means of probing biological cells because it reduces autofluorescence, but the need for direct contact between the cell surface and the microscope slide hinders chemical access to the cell surface. In this work, a submicrometer crystalline layer of colloidal silica on the microscope coverslip is shown to allow TIRF microscopy while also allowing chemical access to the cell surface. A 750 nm layer of 165 nm silica colloidal crystals was sintered onto a fused silica coverslip, and Chinese hamster ovary cells were successfully grown on this surface. This cell line over-expresses the human delta-opioid receptor, which enabled probing of the binding of a labeled ligand to the receptors on the cell surface. Total internal reflection and chemical access to the cell surface are demonstrated. The range of angles for total internal reflection is reduced only by 1/3 due to the lower index of refraction of the colloidal multilayer relative to fused silica.

  17. [Determination of baicalin and total flavonoids in Radix scutellariae by near infrared diffuse reflectance spectroscopy].

    PubMed

    Huang, Qian-qian; Pan, Rui-le; Wei, Jian-he; Wu, Yan-wei; Zhang, Lu-da

    2009-09-01

    The objective of the present study was to develop a method for rapid determination of baicalin and total flavonoids in radix scutellariae by near infrared diffuse reflectance spectroscopy. Sixty one samples of radix scutellariae from different areas containing baicalin of 12.24%-21.34% and total flavonoids of 16.08%-26.52% were used. The range of 8000-4000 cm(-1) of near infrared spectra (NIRS) was selected. Calibration models were established using the PLS(partial least squares). Different spectra pretreatment methods were compared and the optimal model was selected. The study showed that first derivative pretreatments and minimum-maximum normalization methods can be used to extracted spectra information thoroughly to analyze the contents of baicalin and total flavonoids, respectively. The correlation coefficient (r) of baicalin was 0.9024, SEC was 1.01 (standard deviation of the calibration sets) and SEP was 0.8764 (standarddeviation ofthe prediction sets). The correlation coefficient(r) of total flavonoids was 0.9527, SEC was 0.7850 and SEP was 0.5211. Results indicated that near infrared diffuse reflectance spectroscopy method can be used to analyze the main active components in radix scutellariae rapidly.

  18. Attenuation of total organic carbon and unregulated trace organic chemicals in U.S. riverbank filtration systems.

    PubMed

    Hoppe-Jones, Christiane; Oldham, Gretchen; Drewes, Jörg E

    2010-08-01

    There is increasing concern regarding the presence of unregulated trace organic chemicals in drinking water supplies that receive discharge from municipal wastewater treatment plants. In comparison to conventional and advanced drinking water treatment, riverbank filtration represents a low-cost and low-energy alternative that can attenuate total organic carbon (TOC) as well as trace organic chemicals (TOrC). This study examined the role of predominant redox conditions, retention time, biodegradable organic carbon, and temperature to achieve attenuation of TOC and TOrC through monitoring efforts at three full-scale RBF facilities in different geographic areas of the United States. The RBF systems investigated in this study were able to act as a reliable barrier for TOC, nitrogen, and certain TOrC. Temperature (seasonal) variation played an important role for the make-up of the river water quality and performance of the RBF systems. Temperatures of less than 10 degrees C did not affect TOC removal but resulted in diminished attenuation of nitrate and select TOrC.

  19. Fast determination of total ginsenosides content in ginseng powder by near infrared reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Hua-cai; Chen, Xing-dan; Lu, Yong-jun; Cao, Zhi-qiang

    2006-01-01

    Near infrared (NIR) reflectance spectroscopy was used to develop a fast determination method for total ginsenosides in Ginseng (Panax Ginseng) powder. The spectra were analyzed with multiplicative signal correction (MSC) correlation method. The best correlative spectra region with the total ginsenosides content was 1660 nm~1880 nm and 2230nm~2380 nm. The NIR calibration models of ginsenosides were built with multiple linear regression (MLR), principle component regression (PCR) and partial least squares (PLS) regression respectively. The results showed that the calibration model built with PLS combined with MSC and the optimal spectrum region was the best one. The correlation coefficient and the root mean square error of correction validation (RMSEC) of the best calibration model were 0.98 and 0.15% respectively. The optimal spectrum region for calibration was 1204nm~2014nm. The result suggested that using NIR to rapidly determinate the total ginsenosides content in ginseng powder were feasible.

  20. Design of an fMRI-compatible optical touch stripe based on frustrated total internal reflection.

    PubMed

    Jarrahi, Behnaz; Wanek, Johann

    2014-01-01

    Previously we developed a low-cost, multi-configurable handheld response system, using a reflective-type intensity modulated fiber-optic sensor (FOS) to accurately gather participants' behavioral responses during functional magnetic resonance imaging (fMRI). Inspired by the popularity and omnipresence of the fingertip-based touch sensing user interface devices, in this paper we present the design of a prototype fMRI-compatible optical touch stripe (OTS) as an alternative configuration. The prototype device takes advantage of a proven frustrated total internal reflection (FTIR) technique. By using a custom-built wedge-shaped optically transparent acrylic prism as an optical waveguide, and a plano-concave lens to provide the required light beam profile, the position of a fingertip touching the surface of the wedge prism can be determined from the deflected light beams that become trapped within the prism by total internal reflection. To achieve maximum sensitivity, the optical design of the wedge prism and lens were optimized through a series of light beam simulations using WinLens 3D Basic software suite. Furthermore, OTS performance and MRI-compatibility were assessed on a 3.0 Tesla MRI scanner running echo planar imaging (EPI) sequences. The results show that the OTS can detect a touch signal at high spatial resolution (about 0.5 cm), and is well suited for use within the MRI environment with average time-variant signal-to-noise ratio (tSNR) loss < 3%.

  1. Phase fluctuations of radio waves experiencing total reflection from a randomly inhomogeneous plasma layer

    NASA Astrophysics Data System (ADS)

    Afanasiev, N. T.; Afanasiev, A. N.; Larunin, O. A.; Markov, V. P.

    2010-05-01

    We examine the problem of small-angle scattering of radio waves experiencing total reflection from a randomly inhomogeneous layer of plasma. We consider the waves to be normally incident on the layer. To take into account the scattering peculiarities in the neighborhood of the reflection point, we introduce an analytical transformation for the eikonal equation solution derived by the perturbation method. This transformation permits calculations of radio-wave phase fluctuations for any monotonous profile of the regular dielectric permittivity of the plasma in the layer. Using this approach, we have derived analytical formulas for the variance and two-dimensional spatial spectrum of phase fluctuations, depending on the three-dimensional power spectrum of plasma fluctuations. We have also estimated a contribution of reflection point fluctuations to the phase fluctuations and determined the limits of applicability of the derived formulas. The presented analytical transformation of the eikonal equation solution can be used to calculate other statistical moments of the radio wave phase in many problems of solar-terrestrial physics where scattering and reflection of radio waves by plasma formations are important.

  2. Refractive Index Imaging of Cells with Variable-Angle Near-Total Internal Reflection (TIR) Microscopy.

    PubMed

    Bohannon, Kevin P; Holz, Ronald W; Axelrod, Daniel

    2017-09-18

    The refractive index in the interior of single cells affects the evanescent field depth in quantitative studies using total internal reflection (TIR) fluorescence, but often that index is not well known. We here present method to measure and spatially map the absolute index of refraction in a microscopic sample, by imaging a collimated light beam reflected from the substrate/buffer/cell interference at variable angles of incidence. Above the TIR critical angle (which is a strong function of refractive index), the reflection is 100%, but in the immediate sub-critical angle zone, the reflection intensity is a very strong ascending function of incidence angle. By analyzing the angular position of that edge at each location in the field of view, the local refractive index can be estimated. In addition, by analyzing the steepness of the edge, the distance-to-substrate can be determined. We apply the technique to liquid calibration samples, silica beads, cultured Chinese hamster ovary cells, and primary culture chromaffin cells. The optical technique suffers from decremented lateral resolution, scattering, and interference artifacts. However, it still provides reasonable results for both refractive index (~1.38) and for distance-to-substrate (~150 nm) for the cells, as well as a lateral resolution to about 1 µm.

  3. Polarizing properties of embedded symmetric trilayer stacks under conditions of frustrated total internal reflection.

    PubMed

    Azzam, Rasheed M A; Perla, Siva R

    2006-03-01

    An all-transparent symmetric trilayer structure, which consists of a high-index center layer coated on both sides by a low-index film and embedded in a high-index prism, can function as an efficient polarizer or polarizing beam splitter under conditions of frustrated total internal reflection over a wide range of incidence angles. For a given set of refractive indices, all possible solutions for the thicknesses of the layers that suppress the reflection of either the p or s polarization at a specified angle, as well as the reflectance of the system for the orthogonal polarization, are determined. A 633 nm design that uses a MgF2-ZnS-MgF2 trilayer embedded in a ZnS prism achieves an extinction ratio (ER) > 40 dB from 50 degrees to 80 degrees in reflection and an ER > 20 dB from 58 degrees to 80 degrees in transmission. IR polarizers that use CaF2-Ge-CaF2 trilayers embedded in a ZnS prism are also considered.

  4. Observation of total external reflection of x rays from a liquid-solid interface

    NASA Astrophysics Data System (ADS)

    Touryanski, A. G.; Pirshin, I. V.

    2007-07-01

    A new experimental scheme for the measurement of the x-ray reflectivity R from a liquid-solid interface in the range of angles of total external reflection is proposed. An x-ray beam is transmitted through a plane channel filled with a liquid under investigation. The channel is formed by two optically polished plates, one of which being the substrate under study. To eliminate the edge effects caused by surface tension, polymer films with a lyophilic coating are used as windows of the channel. For wate-silicon and glycerol-silicon interfaces, the angular dependences of R and the parameters of the interfaces are measured with the scheme developed using the CuK α (8.05 keV) and CuK β (8.91 keV) lines.

  5. Total internal reflection-based planar waveguide solar concentrator with symmetric air prisms as couplers.

    PubMed

    Xie, Peng; Lin, Huichuan; Liu, Yong; Li, Baojun

    2014-10-20

    We present a waveguide coupling approach for planar waveguide solar concentrator. In this approach, total internal reflection (TIR)-based symmetric air prisms are used as couplers to increase the coupler reflectivity and to maximize the optical efficiency. The proposed concentrator consists of a line focusing cylindrical lens array over a planar waveguide. The TIR-based couplers are located at the focal line of each lens to couple the focused sunlight into the waveguide. The optical system was modeled and simulated with a commercial ray tracing software (Zemax). Results show that the system used with optimized TIR-based couplers can achieve 70% optical efficiency at 50 × geometrical concentration ratio, resulting in a flux concentration ratio of 35 without additional secondary concentrator. An acceptance angle of ± 7.5° is achieved in the x-z plane due to the use of cylindrical lens array as the primary concentrator.

  6. Superresolution confocal technology for displacement measurements based on total internal reflection

    SciTech Connect

    Kuang Cuifang; Hao Xiang; Wang Tingting; Liu Xu; Ali, M. Yakut

    2010-10-15

    In order to achieve a higher axial resolution for displacement measurement, a novel method is proposed based on total internal reflection filter and confocal microscope principle. A theoretical analysis of the basic measurement principles is presented. The analysis reveals that the proposed confocal detection scheme is effective in enhancing the resolution of nonlinearity of the reflectance curve greatly. In addition, a simple prototype system has been developed based on the theoretical analysis and a series of experiments have been performed under laboratory conditions to verify the system feasibility, accuracy, and stability. The experimental results demonstrate that the axial resolution in displacement measurements is better than 1 nm in a range of 200 nm which is threefold better than that can be achieved using the plane reflector.

  7. Processing and attenuation of noise in deep seismic-reflection data from the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Hutchinson, D. R.; Lee, M. W.

    1989-03-01

    The U.S. Geological Survey deep crustal studies reflection profile across the Gulf of Maine off southeastern New England was affected by three sources of noise: side-scattered noise, multiples, and 20-Hz whale sounds. The special processing most effective in minimizing this noise consisted of a combination of frequency-wavenumber (F-K) filtering, predictive deconvolution, and spectral whitening, each applied in the shot domain (prestack). Application of the F-K filter to remove side-scatter noise in the poststack domain resulted in a much poorer quality profile. The prestack noise suppression processing techniques resulted in a reflection profile with good signal-to-noise ratios and reliable strong reflections, especially at depths equivalent to the lower crust (24 34 km). Certain geologic features, such as a buried rift basin and a crustal fault are resolved much better within the upper crust after this processing. Finite difference migration of these data using realistic velocities produced excellent results. Migration was essential to distinguish between abundant dipping and subhorizontal reflections in the lower crust as well as to show an essentially transparent upper mantle.

  8. Processing and attenuation of noise in deep seismic-reflection data from the Gulf of Maine

    USGS Publications Warehouse

    Hutchinson, D.R.; Lee, M.W.

    1989-01-01

    The U.S. Geological Survey deep crustal studies reflection profile across the Gulf of Maine off southeastern New England was affected by three sources of noise: side-scattered noise, multiples, and 20-Hz whale sounds. The special processing most effective in minimizing this noise consisted of a combination of frequency-wavenumber (F-K) filtering, predictive deconvolution, and spectral whitening, each applied in the shot domain (prestack). Application of the F-K filter to remove side-scatter noise in the poststack domain resulted in a much poorer quality profile. The prestack noise suppression processing techniques resulted in a reflection profile with good signal-to-noise ratios and reliable strong reflections, especially at depths equivalent to the lower crust (24-34 km). Certain geologic features, such as a buried rift basin and a crustal fault are resolved much better within the upper crust after this processing. Finite difference migration of these data using realistic velocities produced excellent results. Migration was essential to distinguish between abundant dipping and subhorizontal reflections in the lower crust as well as to show an essentially transparent upper mantle. ?? 1989 Kluwer Academic Publishers.

  9. Physical Activity Attenuates Total and Cardiovascular Mortality Associated With Physical Disability: A National Cohort of Older Adults.

    PubMed

    Martinez-Gomez, David; Guallar-Castillon, Pilar; Higueras-Fresnillo, Sara; Garcia-Esquinas, Esther; Lopez-Garcia, Esther; Bandinelli, Stefania; Rodríguez-Artalejo, Fernando

    2017-06-16

    Regular physical activity (PA) has been shown to protect against disability onset but, once the disability is present, it is unclear if PA might attenuate its harmful health consequences. Thus, we examined if mortality risk associated with physical disability can be offset by PA among older adults. We used data from a cohort of 3,752 individuals representative of the noninstitutionalized population aged 60 years and older in Spain. In 2000-2001, participants self-reported both PA levels (inactive, occasionally, monthly, weekly) and five physical disabilities (agility, mobility, global daily activities, instrumental activities of daily living, and self-care). Individuals were prospectively followed through 2014 to assess incident deaths. The mean follow-up was 10.8 years, with a total of 1,727 deaths, 638 of them due to cardiovascular disease (CVD). All disability types were associated with higher total and CVD mortality. Being physically active (ie, doing any PA) was associated with a statistically significant 26%-37% and 35%-50% lower risk of total and CVD death, respectively, across types of disability. As compared with those being physically active and without disability, those who were inactive and had a disability showed the highest mortality risk from total (hazard ratios from 1.52 to 1.90 across disabilities, all p < .05) and from CVD (hazard ratios from 1.99 to 2.24 across disabilities, all p < .05). Total and CVD mortality risk was similar in physically active participants with disabilities and in inactive individuals without disability. In older adults, PA could attenuate the increased risk of mortality associated with physical disability.

  10. Synchrotron total reflection X-ray fluorescence at BL-16 microfocus beamline of Indus-2

    SciTech Connect

    Tiwari, M. K. Singh, A. K. Das, Gangadhar Chowdhury, Anupam Lodha, G. S.

    2014-04-24

    Determination of ultra trace elements is important in many disciplines both in basic and applied sciences. Numerous applications show their importance in medical science, environmental science, materials science, food processing and semiconductor industries and in maintaining the quality control of ultra pure chemicals and reagents. We report commissioning of a synchrotron based total reflection x-ray fluorescence (TXRF) facility on the BL-16 microfocus beamline of Indus-2. This paper describes the performance of the BL-16 TXRF spectrometer and the detailed description of its capabilities through examples of measured results.

  11. Synchrotron total reflection X-ray fluorescence at BL-16 microfocus beamline of Indus-2

    NASA Astrophysics Data System (ADS)

    Tiwari, M. K.; Singh, A. K.; Das, Gangadhar; Chowdhury, Anupam; Lodha, G. S.

    2014-04-01

    Determination of ultra trace elements is important in many disciplines both in basic and applied sciences. Numerous applications show their importance in medical science, environmental science, materials science, food processing and semiconductor industries and in maintaining the quality control of ultra pure chemicals and reagents. We report commissioning of a synchrotron based total reflection x-ray fluorescence (TXRF) facility on the BL-16 microfocus beamline of Indus-2. This paper describes the performance of the BL-16 TXRF spectrometer and the detailed description of its capabilities through examples of measured results.

  12. Energy Flux and Density of Nonuniform Electromagnetic Waves with Total Reflection

    NASA Astrophysics Data System (ADS)

    Petrov, N. S.

    2014-07-01

    Analytic expressions are obtained for the energy flux and density of refracted nonuniform waves produced during total reflection at the boundary between two isotropic media for the general case of elliptically polarized incident light. The average values are determined as functions of the parameters of the adjoining media and the angle of incidence. The cases of linearly and circularly polarized incident waves are examined in detail. An explicit general expression relating the energy fl ux and density of these waves for arbitrarily polarized incident light is obtained.

  13. Total internal reflection ellipsometry and SPR detection of low molecular weight environmental toxins

    NASA Astrophysics Data System (ADS)

    Nabok, A. V.; Tsargorodskaya, A.; Hassan, A. K.; Starodub, N. F.

    2005-06-01

    The environmental toxins, such as herbicides simazine and atrazine, and T2 mycotoxin were registered with the optical methods of surface plasmon resonance (SPR) and recently developed total internal reflection ellipsometry (TIRE). The immune assay approach was exploited for in situ registration of the above low molecular weight toxins with specific antibodies immobilised onto the gold surface via (poly)allylamine hydrochloride layer using electrostatic self-assembly (ESA) technique. The comparison of two methods of SPR and TIRE shows a higher sensitivity of the latter.

  14. Three-dimensional characterization of tethered microspheres by total internal reflection fluorescence microscopy

    NASA Technical Reports Server (NTRS)

    Blumberg, Seth; Gajraj, Arivalagan; Pennington, Matthew W.; Meiners, Jens-Christian

    2005-01-01

    Tethered particle microscopy is a powerful tool to study the dynamics of DNA molecules and DNA-protein complexes in single-molecule experiments. We demonstrate that stroboscopic total internal reflection microscopy can be used to characterize the three-dimensional spatiotemporal motion of DNA-tethered particles. By calculating characteristic measures such as symmetry and time constants of the motion, well-formed tethers can be distinguished from defective ones for which the motion is dominated by aberrant surface effects. This improves the reliability of measurements on tether dynamics. For instance, in observations of protein-mediated DNA looping, loop formation is distinguished from adsorption and other nonspecific events.

  15. Three-dimensional characterization of tethered microspheres by total internal reflection fluorescence microscopy

    NASA Technical Reports Server (NTRS)

    Blumberg, Seth; Gajraj, Arivalagan; Pennington, Matthew W.; Meiners, Jens-Christian

    2005-01-01

    Tethered particle microscopy is a powerful tool to study the dynamics of DNA molecules and DNA-protein complexes in single-molecule experiments. We demonstrate that stroboscopic total internal reflection microscopy can be used to characterize the three-dimensional spatiotemporal motion of DNA-tethered particles. By calculating characteristic measures such as symmetry and time constants of the motion, well-formed tethers can be distinguished from defective ones for which the motion is dominated by aberrant surface effects. This improves the reliability of measurements on tether dynamics. For instance, in observations of protein-mediated DNA looping, loop formation is distinguished from adsorption and other nonspecific events.

  16. Quantitative imaging of cellular adhesion by total internal reflection holographic microscopy.

    PubMed

    Ash, William M; Krzewina, Leo; Kim, Myung K

    2009-12-01

    Total internal reflection (TIR) holographic microscopy uses a prism in TIR as a near-field imager to perform quantitative phase microscopy of cell-substrate interfaces. The presence of microscopic organisms, cell-substrate interfaces, adhesions, and tissue structures on the prism's TIR face causes relative index of refraction and frustrated TIR to modulate the object beam's evanescent wave phase front. We present quantitative phase images of test specimens such as Amoeba proteus and cells such as SKOV-3 and 3T3 fibroblasts.

  17. Innovative light collimator with afocal lens and total internal reflection lens for daylighting system.

    PubMed

    Chen, Bo-Jian; Chen, Yin-Ti; Ullah, Irfan; Chou, Chun-Han; Chan, Kai-Cyuan; Lai, Yi-Lung; Lin, Chia-Ming; Chang, Cheng-Ming; Whang, Allen Jong-Woei

    2015-10-01

    This research presents a novel design of the collimator, which uses total internal reflection (TIR), convex, and concave lenses for the natural light illumination system (NLIS). The concept of the NLIS is to illuminate building interiors with natural light, which saves energy consumption. The TIR lens is used to collimate the light, and convex and concave lenses are used to converge the light to the required area. The results have shown that the efficiency in terms of achieving collimated light using the proposed collimator at the output of the light collector is better than that of a previous system without a collimator.

  18. Frustrated total internal reflection and critical coupling in a thick plasmonic grating with narrow slits

    SciTech Connect

    Mattiucci, N.; D'Aguanno, G. E-mail: giuseppe.daguanno@us.army.mil; Bloemer, M. J.; Alù, A.

    2014-06-02

    We demonstrate the possibility of critical coupling through frustrated total internal reflection in a thick plasmonic grating below the first diffraction order. Differently from conventional approaches relying on the excitation of surface plasmon-polaritons, here we exploit the light coupling with the leaky modes supported by the grating. This mechanism entails a wide-angle coupling and effectively access spectral bands that would otherwise be difficult to probe using conventional plasmonic critical coupling techniques, such as the Otto configuration. Our finding may pave the way to efficient plasmonic bio-sensor devices.

  19. Total Internal Reflection Tomography (TIRT) for Three-Dimensional Sub-Wavelength Imaging

    NASA Technical Reports Server (NTRS)

    Fischer, David G.; Carney, P. Scott

    2002-01-01

    We will present a novel new form of near-field microscopy known as total internal reflection tomography (TIRT), which allows for true three-dimensional sub-wavelength imaging. It is based on recent theoretical advances regarding the fundamental interaction of light with sub-wavelength structures, as well as stable algorithms for the near-field inverse problem. We will discuss its theoretical underpinnings, as well describe current efforts at the NASA Glenn Research Center to implement a TIRT system for biofluid research.

  20. Single-particle evanescent light scattering simulations for total internal reflection microscopy

    NASA Astrophysics Data System (ADS)

    Helden, Laurent; Eremina, Elena; Riefler, Norbert; Hertlein, Christopher; Bechinger, Clemens; Eremin, Yuri; Wriedt, Thomas

    2006-10-01

    We simulate and measure light scattering of a micrometer-sized spherical particle suspended in solution close to a glass substrate. The model, based on the discrete sources method, is developed to describe the experimental situation of total internal reflection microscopy experiments; i.e., the particle is illuminated by an evanescent light field originating from the glass-solvent interface. In contrast to the well-established assumption of a simple exponential decay of the scattering intensity with distance, we demonstrate significant deviations for a certain range of penetration depths and polarization states of the incident light.

  1. Comparison of T-matrix method with discrete sources method applied for total internal reflection microscopy

    NASA Astrophysics Data System (ADS)

    Riefler, Norbert; Eremina, Elena; Hertlein, Christopher; Helden, Laurent; Eremin, Yuri; Wriedt, Thomas; Bechinger, Clemens

    2007-07-01

    In the paper we applied a variant of the T-matrix method, the null-field method with discrete sources (NFM-DS) and the discrete sources method (DSM) to model light scattering by a particle near a plane surface in an evanescent wave field. Such investigations have a great practical value for total internal reflection microscopy (TIRM). The numerical algorithms of DSM and NFM-DS have been modified to model the specific conditions of real measurement experiments carried out in Stuttgart University. Objective response and scattering cross-section have been calculated. Numerical results of both methods have been compared and demonstrate good agreement with measurements.

  2. Single-particle evanescent light scattering simulations for total internal reflection microscopy.

    PubMed

    Helden, Laurent; Eremina, Elena; Riefler, Norbert; Hertlein, Christopher; Bechinger, Clemens; Eremin, Yuri; Wriedt, Thomas

    2006-10-01

    We simulate and measure light scattering of a micrometer-sized spherical particle suspended in solution close to a glass substrate. The model, based on the discrete sources method, is developed to describe the experimental situation of total internal reflection microscopy experiments; i.e., the particle is illuminated by an evanescent light field originating from the glass-solvent interface. In contrast to the well-established assumption of a simple exponential decay of the scattering intensity with distance, we demonstrate significant deviations for a certain range of penetration depths and polarization states of the incident light.

  3. Total internal reflection fluorescence microscopy study of spiral Ca2+ waves in single heart cell.

    PubMed

    Bai, Y; Tang, A; Wang, S; Zhu, X

    2008-03-01

    Spiral wave phenomena exist in many scales of nature and have attracted the attention of scientists from different fields. Although much work has been done on qualitative analysis of spiral waves, the mechanism of spiral waves' spontaneous formation and termination in living systems is still not clear. Here, by using total internal reflection fluorescence microscopy, we show the spiral waves of calcium signals in single rat cardiac myocytes and the simulation of the waves comprising calcium sparks. The mechanism of the formation and termination of spiral waves is attributable to the calcium release channels' refractory resulting from their stochastic release. We suggest that this mechanism can be adapted to other living systems.

  4. Microplate-compatible total internal reflection fluorescence microscopy for receptor pharmacology

    NASA Astrophysics Data System (ADS)

    Chen, Minghan; Zaytseva, Natalya V.; Wu, Qi; Li, Min; Fang, Ye

    2013-05-01

    We report the use of total internal reflection fluorescence (TIRF) microscopy for analyzing receptor pharmacology and the development of a microplate-compatible TIRF imaging system. Using stably expressed green fluorescence protein tagged β2-adrenergic receptor as the reporter, we found that the activation of different receptors results in distinct kinetic signatures of the TIRF intensity of cells. These TIRF signatures closely resemble the characteristics of their respective label-free dynamic mass redistribution signals in the same cells. This suggests that TIRF in microplate can be used for profiling and screening drugs.

  5. Continuous refractive index dispersion measurement based on derivative total reflection method

    NASA Astrophysics Data System (ADS)

    Deng, Zhichao; Wang, Jin; Ye, Qing; Sun, Tengqian; Zhou, Wenyuan; Mei, Jianchun; Zhang, Chunping; Tian, Jianguo

    2015-04-01

    Traditionally, continuous refractive index dispersion (CRID) measurement of materials with scattering is hard to realize. In this paper, CRID measurement based on the derivative total reflection method (CRIDM-DTRM) is proposed to measure the CRID of both absorption and scattering materials. It effectively determined the CRID of K9 glass, concentrated milk, and 0.5% methyl red solution in the 400-750 nm range with the spectral resolution of about 0.259 nm. For the first time, CRID of a scattering material is measured. CRIDM-DTRM is a useful technique in the field of RID measurement, especially for biotissues and anomalous dispersion materials.

  6. Thin-film-based sensitivity enhancement for total internal reflection fluorescence live-cell imaging.

    PubMed

    Kim, Kyujung; Cho, Eun-Jin; Huh, Yong-Min; Kim, Donghyun

    2007-11-01

    We investigated experimentally the evanescent field enhancement based on dielectric thin films in total internal reflection microscopy. The sample employed two layers of Al2O3 and SiO2 deposited on an SF10 glass substrate. Field intensity enhancement measured by fluorescent excitation of microbeads relative to that of a control sample without dielectric films was polarization dependent, determined as 4.2 and 2.4 for TE and TM polarizations, respectively, and was in good agreement with numerical results. The thin-film-based field enhancement was also applied to live-cell imaging of quantum dots, which confirmed the sensitivity enhancement qualitatively.

  7. Nanograting-based plasmon enhancement for total internal reflection fluorescence microscopy of live cells.

    PubMed

    Kim, Kyujung; Kim, Dong Jun; Cho, Eun-Jin; Suh, Jin-Suck; Huh, Yong-Min; Kim, Donghyun

    2009-01-07

    We investigated evanescent field enhancement based on subwavelength nanogratings for improved sensitivity in total internal reflection microscopy of live cells. The field enhancement is associated with subwavelength-grating-coupled plasmon excitation. An optimum sample employed a silver grating on a silver film and an SF10 glass substrate. Field intensity was enhanced by approximately 90% when measured by fluorescent excitation of microbeads relative to that on a bare prism as a control, which is in good agreement with numerical results. The subwavelength-grating-mediated field enhancement was also applied to live cell imaging of quantum dots, which confirmed the sensitivity enhancement qualitatively.

  8. First Total Reflection X-Ray Fluorescence round-robin test of water samples: Preliminary results

    NASA Astrophysics Data System (ADS)

    Borgese, Laura; Bilo, Fabjola; Tsuji, Kouichi; Fernández-Ruiz, Ramón; Margui, Eva; Streli, Christina; Pepponi, Giancarlo; Stosnach, Hagen; Yamada, Takashi; Vandenabeele, Peter; Maina, David M.; Gatari, Michael; Shepherd, Keith D.; Towett, Erick K.; Bennun, Leonardo; Custo, Graciela; Vasquez, Cristina; Depero, Laura E.

    2014-11-01

    Total Reflection X-Ray Fluorescence (TXRF) is a mature technique to evaluate quantitatively the elemental composition of liquid samples deposited on clean and well polished reflectors. In this paper the results of the first worldwide TXRF round-robin test of water samples, involving 18 laboratories in 10 countries are presented and discussed. The test was performed within the framework of the VAMAS project, interlaboratory comparison of TXRF spectroscopy for environmental analysis, whose aim is to develop guidelines and a standard methodology for biological and environmental analysis by means of the TXRF analytical technique.

  9. Superluminal energy transmission in the Goos-Hanchen shift of total reflection

    NASA Astrophysics Data System (ADS)

    Wang, Zhong-Yue

    2011-04-01

    The dispersion relation ω2 = β2c2 - τ2c2 of surface electromagnetic waves is corresponding to that E2 = p2c2 - m02c4 of a tachyon where the coefficient of proportionality is the squared Planck constant ℏ2. Then we prove the energy flow velocity of the Goos-Hanchen shift in vacuum is cn sin θi > c as well according to electrodynamics. These two different ways lead to a same conclusion that energy transport in the Goos-Hanchen effect of total reflection is faster than light.

  10. Application of transparent nanostructured electrodes for modulation of total internal reflection

    NASA Astrophysics Data System (ADS)

    Hrudey, P. C. P.; Martinuk, M. A.; Mossman, M. A.; van Popta, A. C.; Brett, M. J.; Dunbar, T. D.; Huizinga, J. S.; Whitehead, L. A.

    2007-09-01

    We present a novel method of modulating total internal reflection (TIR) from an optical surface using a solution of dye ions in combination with a nanostructured electrode. Previous work using the electrophoretic movement of pigment particles to modulate TIR was limited by agglomeration of the pigment over time. Dye ions do not suffer from this limitation, but because of their small size they have significantly smaller absorption cross-section per unit charge than pigment particles which are generally two orders of magnitude larger. This significantly limits the maximum absorption caused by electrostatic attraction of the ions to a transparent conductive electrode. This can be overcome by using a transparent conductive nanoporous thin film as the electrode in which the porosity increases the effective surface area, allowing more dye ions to move into the evanescent wave region near the nanoporous transparent electrode and thus substantially increases the amount of absorption. In this paper, we demonstrate the modulation of TIR by observing the time-dependent variation of the reflectance as the dye ions are moved into and out of the evanescent wave region. This approach may have applications in reflective displays and active diffractive devices.

  11. Reflection effects during the radiation sterilization of ultra high molecular weight polyethylene for total knee replacements.

    PubMed

    Barron, Declan; Birkinshaw, Colin; Collins, Maurice N

    2015-08-01

    Ultra high molecular weight polyethylene has been subject to γ irradiation whilst in contact with a stainless steel backing. This leads to reflection of the incident radiation and to backscattered electrons, both of which contribute to an effective increase in dose received. Radiation induced damage through scission of inter-lamellae tie chains results in an increase in crystallinity. At a nominal received dose of 100 kGy the effect of the metal backing is to increase crystallinity by approximately a third relative to the increase observed in materials irradiated in the absence of the backing. The metal backing induced reflections cause a bimodal recrystallization distribution giving rise to a more refined crystal population. As implant materials are subject to intermittent, but high, stress levels it is clearly of importance to examine how these reflection induced structural changes influence mechanical properties. Stress/strain results have indicated that subsequent yielding behavior is governed by the counteracting mechanisms of crystal growth and lamella reorganization mechanisms and in metal backed components the resulting morphological inhomogeneity may have important property consequences for wear induced failures in total knee replacement materials.

  12. Wave intensity amplification and attenuation in non-linear flow: implications for the calculation of local reflection coefficients.

    PubMed

    Mynard, Jonathan; Penny, Daniel J; Smolich, Joseph J

    2008-12-05

    Local reflection coefficients (R) provide important insights into the influence of wave reflection on vascular haemodynamics. Using the relatively new time-domain method of wave intensity analysis, R has been calculated as the ratio of the peak intensities (R(PI)) or areas (R(CI)) of incident and reflected waves, or as the ratio of the changes in pressure caused by these waves (R(DeltaP)). While these methods have not yet been compared, it is likely that elastic non-linearities present in large arteries will lead to changes in the size of waves as they propagate and thus errors in the calculation of R(PI) and R(CI). To test this proposition, R(PI), R(CI) and R(DeltaP) were calculated in a non-linear computer model of a single vessel with various degrees of elastic non-linearity, determined by wave speed and pulse amplitude (DeltaP(+)), and a terminal admittance to produce reflections. Results obtained from this model demonstrated that under linear flow conditions (i.e. as DeltaP(+)-->0), R(DeltaP) is equivalent to the square-root of R(PI) and R(CI) (denoted by R(PI)(p) and R(CI)(p)). However for non-linear flow, pressure-increasing (compression) waves undergo amplification while pressure-reducing (expansion) waves undergo attenuation as they propagate. Consequently, significant errors related to the degree of elastic non-linearity arise in R(PI) and R(CI), and also R(PI)(p) and R(CI)(p), with greater errors associated with larger reflections. Conversely, R(Delta)(P) is unaffected by the degree of non-linearity and is thus more accurate than R(PI) and R(CI).

  13. Nanostructured surface fabricated by laser interference lithography to attenuate the reflectivity of microlens arrays

    NASA Astrophysics Data System (ADS)

    Baroni, P.-Y.; Päivänranta, B.; Scharf, T.; Nakagawa, W.; Roussey, M.; Kuittinen, M.; Herzig, H. P.

    2010-01-01

    A subwavelength-scale square lattice optical meta-material is fabricated using an interference photolithography process on the surface of a quartz microlens array. This nanostructuring of the quartz surface introduces an antireflective effect, reducing reflectivity between 10% and 30% and enhancing the transmissivity 3% in the visible spectrum. This approach permits fast fabrication on a 4-inch wafer covered with microlenses (non-flat surface) and produces monolithic devices which are robust to adverse environments such as temperature variations.

  14. Variable-angle total internal reflection fluorescence microscopy of intact cells of Arabidopsis thaliana

    PubMed Central

    2011-01-01

    Background Total internal reflection fluorescence microscopy (TIRFM) is a powerful tool for observing fluorescently labeled molecules on the plasma membrane surface of animal cells. However, the utility of TIRFM in plant cell studies has been limited by the fact that plants have cell walls, thick peripheral layers surrounding the plasma membrane. Recently, a new technique known as variable-angle epifluorescence microscopy (VAEM) was developed to circumvent this problem. However, the lack of a detailed analysis of the optical principles underlying VAEM has limited its applications in plant-cell biology. Results Here, we present theoretical and experimental evidence supporting the use of variable-angle TIRFM in observations of intact plant cells. We show that when total internal reflection occurs at the cell wall/cytosol interface with an appropriate angle of incidence, an evanescent wave field of constant depth is produced inside the cytosol. Results of experimental TIRFM observations of the dynamic behaviors of phototropin 1 (a membrane receptor protein) and clathrin light chain (a vesicle coat protein) support our theoretical analysis. Conclusions These findings demonstrate that variable-angle TIRFM is appropriate for quantitative live imaging of cells in intact tissues of Arabidopsis thaliana. PMID:21943324

  15. Modeling total and polarized reflectances of ice clouds: evaluation by means of POLDER and ATSR-2 measurements.

    PubMed

    Knap, Wouter H; Labonnote, Laurent C; Brogniez, Gérard; Stammes, Piet

    2005-07-01

    Four ice-crystal models are tested by use of ice-cloud reflectances derived from Along Track Scanning Radiometer-2 (ATSR-2) and Polarization and Directionality of Earth's Reflectances (POLDER) radiance measurements. The analysis is based on dual-view ATSR-2 total reflectances of tropical cirrus and POLDER global-scale total and polarized reflectances of ice clouds at as many as 14 viewing directions. Adequate simulations of ATSR-2 total reflectances at 0.865 microm are obtained with model clouds consisting of moderately distorted imperfect hexagonal monocrystals (IMPs). The optically thickest clouds (tau > approximately 16) in the selected case tend to be better simulated by use of pure hexagonal monocrystals (PHMs). POLDER total reflectances at 0.670 microm are best simulated with columnar or platelike IMPs or columnar inhomogeneous hexagonal monocrystals (IHMs). Less-favorable simulations are obtained for platelike IHMs and polycrystals (POLYs). Inadequate simulations of POLDER total and polarized reflectances are obtained for model clouds consisting of PHMs. Better simulations of the POLDER polarized reflectances at 0.865 microm are obtained with IMPs, IHMs, or POLYs, although POLYs produce polarized reflectances that are systematically lower than most of the measurements. The best simulations of the polarized reflectance for the ice-crystal models assumed in this study are obtained for model clouds consisting of columnar IMPs or IHMs.

  16. [Estimating total nitrogen content in wetland vegetation based on measured reflectance spectra].

    PubMed

    Liu, Ke; Zhao, Wen-ji; Guo, Xiao-yu; Wang, Yi-hong; Sun, Yong-hua; Miao, Qian

    2012-02-01

    More and more urban wetlands have been supplied with reclaimed water. And monitoring the growth condition of large-area wetland vegetation is playing a very important role in wetland restoration and reconstruction. Recently, remote sensing technology has become an important tool for vegetation growth monitoring. The South Wetland in the Olympic Park, a typical wetland using reused water, was selected as the research area. The leaf reflectance spectra and were acquired for the main wetland plants reed (Phragmites australis) and cattail (Typha angustifolia) with an ASD FieldSpec 3 spectrometer (350 2 500 nm). The total nitrogen (TN) content of leaf samples was determined by Kjeldahl method subsequently. The research established univariate models involving simple ratio spectral index (SR) model and normalized difference spectral index (ND) model, as well as multivariate models including stepwise multiple linear regression (SMLR) model and partial least squares regression (PLSR) model. Moreover, the accuracy of all the models was tested through cross-validated coefficient of determination (R2(CV)) and cross-validated root mean square error (RMSE(CV)). The results showed that (1) comparing different types of wetland plants, the accuracy of all established prediction models using Phragmites australis reflectance spectra was higher than that using Typha angustifolia reflectance spectra. (2) compared with univariate techniques, multivariate regressions improved the estimation of TN concentration in leaves. (3) among the various investigated models, the accuracy of PLSR model was the highest (R2(CV) = 0.80, RMSE(CV) = 0.24). PLSR provided the most useful explorative tool for unraveling the relationship between spectral reflectance and TN consistence of leaves. The result would not only provide a scientific basis for remote sensing retrieval of biochemical variables of wetland vegetation, but also provide a strong scientific basis for the monitoring and management of urban

  17. Stable isotopes of nitrate reflect natural attenuation of propellant residues on military training ranges.

    PubMed

    Bordeleau, Geneviève; Savard, Martine M; Martel, Richard; Smirnoff, Anna; Ampleman, Guy; Thiboutot, Sonia

    2013-08-06

    Nitroglycerin (NG) and nitrocellulose (NC) are constituents of double-base propellants used notably for firing antitank ammunitions. Nitroglycerin was detected in soil and water samples from the unsaturated zone (pore water) at an active antitank firing position, where the presence of high nitrate (NO3(-)) concentrations suggests that natural attenuation of NG is occurring. However, concentrations alone cannot assess if NG is the source of NO3(-), nor can they determine which degradation processes are involved. To address this issue, isotopic ratios (δ(15)N, δ(18)O) were measured for NO3(-) produced from NG and NC through various controlled degradation processes and compared with ratios measured in field pore water samples. Results indicate that propellant combustion and degradation mediated by soil organic carbon produced the observed NO3(-) in pore water at this site. Moreover, isotopic results are presented for NO3(-) produced through photolysis of propellant constituents, which could be a dominant process at other sites. The isotopic data presented here constitute novel information regarding a source of NO3(-) that was practically not documented before and a basis to study the contamination by energetic materials in different contexts.

  18. Attenuation fluctuations and local dermal reflectivity are indicators of immune cell infiltrate and epidermal hyperplasia in skin inflammation

    NASA Astrophysics Data System (ADS)

    Phillips, Kevin G.; Wang, Yun; Choudhury, Niloy; Levitz, David; Swanzey, Emily; Lagowski, James; Kulesz-Martin, Molly; Jacques, Steven

    2012-02-01

    Psoriasis is a common inflammatory skin disease resulting from genetic and environmental alterations of cutaneous immune responses responsible for skin homeostasis. While numerous therapeutic targets involved in the immunopathogenesis of psoriasis have been identified, the in vivo dynamics of psoriasis remains under investigated. To elucidate the spatial-temporal morphological evolution of psoriasis we undertook in vivo time course focus-tracked optical coherence tomography (OCT) imaging to non-invasively document dermal alterations due to immune cell infiltration and epidermal hyperplasia in an Imiquimod (IMQ) induced model of psoriasis-like inflammation in DBA2/C57Bl6 hybrid mice. Quantitative appraisal of dermal architectural changes was achieved through a three parameter fit of OCT axial scans in the dermis of the form A(z) = ρ exp(-mu;z +ɛ(z)). Ensemble averaging of the fit parameters over 2000 axial scans per mouse in each treatment arm revealed that the local dermal reflectivity ρ, decreased significantly in response to 6 day IMQ treatment (p = 0.0001), as did the standard deviation of the attenuation fluctuation std(ɛ(z)), (p = 0.04), in comparison to cream controls and day 1 treatments. No significant changes were observed in the average dermal attenuation rate, μ. Our results suggest these label-free OCT-based metrics can be deployed to investigate new therapeutic targets in animal models as well as aid in clinical staging of psoriasis in conjunction with the psoriasis area and severity index.

  19. Bromine and bromide content in soils: Analytical approach from total reflection X-ray fluorescence spectrometry.

    PubMed

    Gallardo, Helena; Queralt, Ignasi; Tapias, Josefina; Candela, Lucila; Margui, Eva

    2016-08-01

    Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample preparation and low-cost analyses are desired. In the present work, the possibilities and drawbacks of low-power total reflection X-ray fluorescence spectrometry (TXRF) for the determination of total bromine and bromide contents in soils were evaluated. The direct analysis of a solid suspension using 20 mg of fine ground soil (<63 μm) gave a 3.7 mg kg(-1) limit of detection for bromine which, in most cases, was suitable for monitoring total bromine content in soils (Br content range in soils = 5-40 mg kg(-1)). Information about bromide determination in soils is also possible by analyzing the Br content in water soil extracts. In this case, the TXRF analysis can be directly performed by depositing 10 μL of the internal standardized soil extract sample on a quartz glass reflector in a measuring time of 1500 s. The bromide limit of detection by this approach was 10 μg L(-1). Good agreement was obtained between the TXRF results for the total bromine and bromide determinations in soils and those obtained by other popular analytical techniques, e.g. energy dispersive X-ray fluorescence spectrometry (total bromine) and ionic chromatography (bromide). As a study case, the TXRF method was applied to study bromine accumulation in two agricultural soils fumigated with a methyl bromide pesticide and irrigated with regenerated waste water.

  20. Estimation of the Diffuse Attenuation Coefficient KdPAR Using MERIS Satellite Reflections for European Coastal Waters

    NASA Astrophysics Data System (ADS)

    Saulquin, Bertand; Hamdi, Anouar; Populus, Jacques; Loutier, Romain; Demaria, Julien; Mangin, Antoine; D'Andon, Odile Fanton

    2010-12-01

    Accurate estimations of the diffuse attenuation coefficient is critical to understand physical processes such as the heat transfer in the upper layer of the ocean and also biological processes such as phytoplankton photosynthesis in the ocean euphotic zone. Light availability in the water column and the seabed determine the euphotic zone and constraints the type and distribution of the algae species. The EuSeaMap project's aim is to characterize at a resolution of 250m the European infralitoral benthic zone, according to biology, physic and geology criteriums and using observations and models. Satellite observations of the diffuse attenuation coefficient of the downwelling spectral irradiance at wavelength 490 nm (Kd490) or the diffuse attenuation coefficient for the downwelling photosynthetically available radiation (KdPAR) is an effective method to provide large scale maps of these parameters at high spatial and temporal resolution. Several empirical and semi-analytical models are commonly used to derive the Kd490 and KdPAR maps from ocean colour satellite sensors such as the Medium Resolution Imaging Spectrometer Instrument (MERIS), the Sea- viewing Wide Field-of-view Sensor (SeaWiFS), and the Moderate Resolution Imaging Spectroradiometer (MODIS). Most of these existing empirical or semi- analytical models have been calibrated on open ocean waters and provide good results in these areas, but tend to underestimate the attenuation of light in coastal waters, our area of interest. We propose here a new estimation of the euphotic depth and the KdPAR for coastal European waters using MERIS reflectances at the resolution of 1km and 250 m. First, a semi-analytical model is used to estimate the Kd490, and in a second step, two relationships have been developed between the KdPAR and the Kd490 for respectively clear and turbid waters. Satellite-derived fields of Kd490 and the deduced KdPAR are validated using matchups collected over the world. Distribution maps of seabed

  1. Transmission and total reflection of subhertz electromagnetic waves at the earth-atmosphere interface

    SciTech Connect

    Shiozawa, Toshiyuki

    2010-12-15

    For the purpose of providing for a theoretical background for the study of electromagnetic fields generated by precursory effects of earthquakes, the problem of transmission and total reflection at the earth-atmosphere interface is investigated in detail for a subhertz plane electromagnetic wave incident from the earth's crust. The term ''subhertz'' means 'below 1 Hz'. First, for the special case of normal incidence, the overall power transmission coefficient at the earth-atmosphere interface is found to take a maximum value at a definite frequency f{sub 0} which is inversely proportional to the square of the depth of a virtual hypocenter. A typical value of f{sub 0} falls around 0.01 Hz. For oblique incidence as well, this feature of the overall power transmission coefficient is retained except in the vicinity of the critical angle of incidence for the H-wave. At the critical angle of incidence, the power flow carried by a surface wave along the interface becomes anomalously large for the H-wave. However, over a wide range of angles of incidence greater than the critical angle, the power flow carried by the E-wave exceeds that carried by the H-wave by orders of magnitude. Finally, the energy conservation relations for the incident, reflected, and transmitted waves at the earth-atmosphere interface are discussed. For an incident wave coming from the earth's crust, the interactive power between the incident and reflected waves plays a crucial role for the conservation of energy at the interface.

  2. Near IR Scanning Angle Total Internal Reflection Raman Spectroscopy at Smooth Gold Films

    SciTech Connect

    McKee, Kristopher; Meyer, Matthew; Smith, Emily

    2012-04-13

    Total internal reflection (TIR) Raman and reflectivity spectra were collected for nonresonant analytes as a function of incident angle at sapphire or sapphire/smooth 50 nm gold interfaces using 785 nm excitation. For both interfaces, the Raman signal as a function of incident angle is well-modeled by the calculated interfacial mean square electric field (MSEF) relative to the incident field times the thickness of the layer being probed in the Raman measurement (D{sub RS}). The Raman scatter was reproducibly enhanced at the interface containing a gold film relative to the sapphire interface by a factor of 4.3–4.6 for aqueous pyridine or 2.2–3.7 for neat nitrobenzene, depending on the analyzed vibrational mode. The mechanism for the increased Raman signal is the enhanced MSEF at incident angles where propagating surface plasmons are excited in the metal film. The background from the TIR prism was reduced by 89–95% with the addition of the gold film, and the percent relative uncertainty in peak area was reduced from 15 to 1.7% for the 1347 cm–1 mode of nitrobenzene. Single monolayers of benzenethiol (S/N = 6.8) and 4-mercaptopyridine (S/N = 16.5) on gold films were measured by TIR Raman spectroscopy with 785 nm excitation (210 mW) without resonant enhancement in 1 min.

  3. Trace elements determination in red and white wines using total-reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Anjos, M. J.; Lopes, R. T.; de Jesus, E. F. O.; Moreira, S.; Barroso, R. C.; Castro, C. R. F.

    2003-12-01

    Several wines produced in different regions from south of Brazil and available in markets in Rio de Janeiro were analyzed for their contents of elements such as: P, S, Cl, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb and Sr. Multi-element analysis was possible with simple sample preparation and subsequent analysis by total-reflection X-ray fluorescence using synchrotron radiation. The measurement was carried at the X-ray fluorescence beamline in the Synchrotron Light Source Laboratory in Campinas, Brazil. The levels of the various elements obtained were lower in the Brazilian wines than the values generally found in the literature. The present study indicates the capability of multi-element analysis for determining the contents of various elements present in wines coming from Brazil vineyards by using a simple, sensitive and precise method.

  4. Imaging with total internal reflection fluorescence microscopy for the cell biologist.

    PubMed

    Mattheyses, Alexa L; Simon, Sanford M; Rappoport, Joshua Z

    2010-11-01

    Total internal reflection fluorescence (TIRF) microscopy can be used in a wide range of cell biological applications, and is particularly well suited to analysis of the localization and dynamics of molecules and events near the plasma membrane. The TIRF excitation field decreases exponentially with distance from the cover slip on which cells are grown. This means that fluorophores close to the cover slip (e.g. within ~100 nm) are selectively illuminated, highlighting events that occur within this region. The advantages of using TIRF include the ability to obtain high-contrast images of fluorophores near the plasma membrane, very low background from the bulk of the cell, reduced cellular photodamage and rapid exposure times. In this Commentary, we discuss the applications of TIRF to the study of cell biology, the physical basis of TIRF, experimental setup and troubleshooting.

  5. Common-path configuration in total internal reflection digital holography microscopy.

    PubMed

    Calabuig, Alejandro; Matrecano, Marcella; Paturzo, Melania; Ferraro, Pietro

    2014-04-15

    Total Internal Reflection Digital Holographic Microscopy (TIRDHM) is recognized to be a powerful tool for retrieving quantitative phase images of cell-substrate interfaces, adhesions, and tissue structures close to the prism surface. In this Letter, we develop an improved TIRDHM system, taking advantage of a refractive index mismatch between the prism and the sample substrate, to allow phase-shifting DH with just a single-beam interferometric configuration. Instead of the traditional off-axis method, phase-shift method is used to retrieve amplitude and phase images in coherent light and TIR modality. Essentially, the substrate-prism interface acts like a beam splitter generating a reference beam, where the phase-shift dependence on the incident angle is exploited in this common-path configuration. With the aim to demonstrate the technique's validity, some experiments are performed to establish the advantage of this compact and simple configuration, in which the reference arm in the setup is avoided.

  6. Total-Internal-Reflection Platforms for Chemical and Biological Sensing Applications

    NASA Astrophysics Data System (ADS)

    Sapsford, Kim E.

    Sensing platforms based on the principle of total internal reflection (TIR) represent a fairly mature yet still expanding and exciting field of research. Sensor development has mainly been driven by the need for rapid, stand-alone, automated devices for application in the fields of clinical diagnosis and screening, food and water safety, environmental monitoring, and chemical and biological warfare agent detection. The technologies highlighted in this chapter are continually evolving, taking advantage of emerging advances in microfabrication, lab-on-a-chip, excitation, and detection techniques. This chapter describes many of the underlying principles of TIR-based sensing platforms and additionally focusses on planar TIR fluorescence (TIRF)-based chemical and biological sensors.

  7. Nanoscale characterization of vesicle adhesion by normalized total internal reflection fluorescence microscopy.

    PubMed

    Cardoso Dos Santos, Marcelina; Vézy, Cyrille; Jaffiol, Rodolphe

    2016-06-01

    We recently proposed a straightforward fluorescence microscopy technique to study adhesion of Giant Unilamellar Vesicles. This technique is based on dual observations which combine epi-fluorescence microscopy and total internal reflection fluorescence (TIRF) microscopy: TIRF images are normalized by epi-fluorescence ones. By this way, it is possible to map the membrane/substrate separation distance with a nanometric resolution, typically ~20 nm, with a maximal working range of 300-400 nm. The purpose of this paper is to demonstrate that this technique is useful to quantify vesicle adhesion from ultra-weak to strong membrane-surface interactions. Thus, we have examined unspecific and specific adhesion conditions. Concerning unspecific adhesion, we have controlled the strength of electrostatic forces between negatively charged vesicles and various functionalized surfaces which exhibit a positive or a negative effective charge. Specific adhesion was highlighted with lock-and-key forces mediated by the well defined biotin/streptavidin recognition.

  8. Topography of Cells Revealed by Variable-Angle Total Internal Reflection Fluorescence Microscopy.

    PubMed

    Cardoso Dos Santos, Marcelina; Déturche, Régis; Vézy, Cyrille; Jaffiol, Rodolphe

    2016-09-20

    We propose an improved version of variable-angle total internal reflection fluorescence microscopy (vaTIRFM) adapted to modern TIRF setup. This technique involves the recording of a stack of TIRF images, by gradually increasing the incident angle of the light beam on the sample. A comprehensive theory was developed to extract the membrane/substrate separation distance from fluorescently labeled cell membranes. A straightforward image processing was then established to compute the topography of cells with a nanometric axial resolution, typically 10-20 nm. To highlight the new opportunities offered by vaTIRFM to quantify adhesion process of motile cells, adhesion of MDA-MB-231 cancer cells on glass substrate coated with fibronectin was examined.

  9. Total internal reflection-based biochip utilizing a polymer-filled cavity with a micromirror sidewall.

    PubMed

    Chronis, Nikolas; Lee, Luke P

    2004-04-01

    A total internal reflection (TIR)-based biochip utilizing a polymer-filled cavity with a micromirror sidewall has been designed and fabricated. The implementation of the micromirror sidewall cavity facilitates precise alignment of the excitation light beam into the system. The incident angle of illumination can be easily modified by selecting polymers of different indices of refraction while optical losses are minimized. The design enables the hybrid, vertical integration of a laser diode and a CCD camera, resulting in a compact optical system. Brownian motion of fluorescent microspheres and real-time photobleaching of rhodamine 6G molecules is demonstrated. The proposed TIR-based chip simplifies current TIR optical configurations and could potentially be used as an optical-microfluidic platform for an integrated lab-on-a-chip microsystem.

  10. Efficient focusing of hard x rays to 25 nm by a total reflection mirror

    SciTech Connect

    Mimura, Hidekazu; Yumoto, Hirokatsu; Matsuyama, Satoshi; Sano, Yasuhisa; Yamamura, Kazuya; Mori, Yuzo; Yabashi, Makina; Nishino, Yoshinori; Tamasaku, Kenji; Ishikawa, Tetsuya; Yamauchi, Kazuto

    2007-01-29

    Nanofocused x rays are indispensable because they can provide high spatial resolution and high sensitivity for x-ray nanoscopy/spectroscopy. A focusing system using total reflection mirrors is one of the most promising methods for producing nanofocused x rays due to its high efficiency and energy-tunable focusing. The authors have developed a fabrication system for hard x-ray mirrors by developing elastic emission machining, microstitching interferometry, and relative angle determinable stitching interferometry. By using an ultraprecisely figured mirror, they realized hard x-ray line focusing with a beam width of 25 nm at 15 keV. The focusing test was performed at the 1-km-long beamline of SPring-8.

  11. Total reflection X-ray spectrometry (TXRF) for trace elements assessment in edible clams.

    PubMed

    Marguí, Eva; de Fátima Marques, Alexandra; de Lurdes Prisal, Maria; Hidalgo, Manuela; Queralt, Ignasi; Carvalho, Maria Luisa

    2014-01-01

    The present contribution presents a preliminary investigation of the chemical composition with respect to major, minor, trace, and ultratrace elements in several clam species that are frequently used for human consumption in Portuguese markets and worldwide. In order to use a simple and rapid analytical methodology for clam analysis, energy dispersive X-ray fluorescence (EDXRF) spectrometry and total reflection X-ray fluorescence (TXRF) spectrometry were selected as analytical techniques. The analytical capabilities of TXRF spectrometry were evaluated for the determination of minor and trace elements in commercial edible clams. We compared the direct analysis of powdered suspensions (using different sample amounts and dispersant agents) with the analysis of the digested samples for trace element determination. Inductively coupled plasma mass spectrometry analysis of clam digests was also performed to evaluate the analytical possibilities of TXRF spectrometry for trace and ultratrace analysis.

  12. Watch your step! A frustrated total internal reflection approach to forensic footwear imaging

    NASA Astrophysics Data System (ADS)

    Needham, J. A.; Sharp, J. S.

    2016-02-01

    Forensic image retrieval and processing are vital tools in the fight against crime e.g. during fingerprint capture. However, despite recent advances in machine vision technology and image processing techniques (and contrary to the claims of popular fiction) forensic image retrieval is still widely being performed using outdated practices involving inkpads and paper. Ongoing changes in government policy, increasing crime rates and the reduction of forensic service budgets increasingly require that evidence be gathered and processed more rapidly and efficiently. A consequence of this is that new, low-cost imaging technologies are required to simultaneously increase the quality and throughput of the processing of evidence. This is particularly true in the burgeoning field of forensic footwear analysis, where images of shoe prints are being used to link individuals to crime scenes. Here we describe one such approach based upon frustrated total internal reflection imaging that can be used to acquire images of regions where shoes contact rigid surfaces.

  13. Tunneling mode in a frustrated total internal reflection structure with hyperbolic metamaterial

    NASA Astrophysics Data System (ADS)

    Luo, Li; Li, Chaoyang; Tang, Tingting

    2016-10-01

    We study the tunneling modes in a frustrated total internal reflection (FTIR) structure with hyperbolic metamaterial (HMM). The physical mechanism of tunneling mode is analyzed by the condition of general zero average permittivity. The influence of anisotropy, loss and dispersion of HMM on tunneling modes is discussed based on simulation results. Tunneling mode merging or splitting can be realized by adjusting the thickness of air or HMM. We can also find the absorption of HMM significantly reduces the transmittance peak of tunneling mode. When a recently reported HMM of ZnAlO/ZnO multilayer is introduced in the FTIR structure, the combined action of HMM loss and dispersion brings many small tunneling modes in the angular spectrum. The tunneling mode in the proposed structure can be used to design filters and wavelength selectors which may also have applications in wavelength de-multiplexing in optical communications.

  14. Total internal reflection fluorescence based multiplane localization microscopy enables super-resolved volume imaging

    NASA Astrophysics Data System (ADS)

    Mondal, Partha Pratim; Hess, Samuel T.

    2017-05-01

    Total internal reflection fluorescence (TIRF) based geometry is attractive for super-resolution localization microscopy. Although the traditional TIRF configuration enables near-surface 2D imaging, it is not capable of imaging multiple axial planes. We propose a simultaneous multiplane imaging based localization encoded (SMILE) technique in the TIRF configuration that utilizes point spread function (PSF) information (PSF size, corresponding to single molecules located at the focal plane and off-focal planes, and the detected photons per PSF) to reconstruct a near-surface volume stack. The natural spread of the detection PSFs (far from the specimen-coverslip interface) is used to fix the axial locations of single molecules, and the corresponding photon count determines their localization precision. The proposed SMILE microscopy technique enables super-resolved volume reconstruction based on 2D recorded data.

  15. Preparation of filamentous actin for polarized total internal reflection fluorescence microscopy (polTIRFM) motility assays.

    PubMed

    Beausang, John F; Sun, Yujie; Quinlan, Margot E; Forkey, Joseph N; Goldman, Yale E

    2012-05-01

    Polarized total internal reflection fluorescence microscopy (polTIRFM) can be used to detect the spatial orientation and rotational dynamics of single molecules. polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. In this protocol, filamentous actin (F-actin) is polymerized from purified, monomeric actin (G-actin) for use in polTIRFM motility assays in which actin interacts with myosin. The procedures include (1) the preparation of unlabeled F-actin from G-actin; (2) the preparation of F-actin that is sparsely labeled with 6'-IATR (6'-iodoacetamidotetramethylrhodamine); and (3) the preparation of F-actin with a combination of unlabeled, biotinylated, and rhodamine-labeled monomers. Rhodamine-phalloidin actin, also used in polTIRFM assays, can be prepared using a procedure similar to the one for unlabeled actin.

  16. Watch your step! A frustrated total internal reflection approach to forensic footwear imaging

    PubMed Central

    Needham, J. A.; Sharp, J. S.

    2016-01-01

    Forensic image retrieval and processing are vital tools in the fight against crime e.g. during fingerprint capture. However, despite recent advances in machine vision technology and image processing techniques (and contrary to the claims of popular fiction) forensic image retrieval is still widely being performed using outdated practices involving inkpads and paper. Ongoing changes in government policy, increasing crime rates and the reduction of forensic service budgets increasingly require that evidence be gathered and processed more rapidly and efficiently. A consequence of this is that new, low-cost imaging technologies are required to simultaneously increase the quality and throughput of the processing of evidence. This is particularly true in the burgeoning field of forensic footwear analysis, where images of shoe prints are being used to link individuals to crime scenes. Here we describe one such approach based upon frustrated total internal reflection imaging that can be used to acquire images of regions where shoes contact rigid surfaces. PMID:26880687

  17. Coherent total internal reflection dark-field microscopy: label-free imaging beyond the diffraction limit.

    PubMed

    von Olshausen, Philipp; Rohrbach, Alexander

    2013-10-15

    Coherent imaging is barely applicable in life-science microscopy due to multiple interference artifacts. Here, we show how these interferences can be used to improve image resolution and contrast. We present a dark-field microscopy technique with evanescent illumination via total internal reflection that delivers high-contrast images of coherently scattering samples. By incoherent averaging of multiple coherent images illuminated from different directions we can resolve image structures that remain unresolved by conventional (incoherent) fluorescence microscopy. We provide images of 190 nm beads revealing resolution beyond the diffraction limit and slightly increased object distances. An analytical model is introduced that accounts for the observed effects and which is confirmed by numerical simulations. Our approach may be a route to fast, label-free, super-resolution imaging in live-cell microscopy.

  18. Analysis of the late steps of exocytosis: biochemical and total internal reflection fluorescence microscopy (TIRFM) studies.

    PubMed

    Holz, Ronald W

    2006-01-01

    1. Time with Julie in his laboratory at the NIH in the early 1970s is remembered. The experience led to a life-long interest in the regulation of catecholamine secretion. Here are summarized aspects of this work. 2. The relationship between ATP-dependent priming of exocytosis and the polyphosphoinositides is reviewed. In addition, studies are summarized in which total internal reflection fluorescent microscopy (TIRFM) was used to visualize secretory granule behavior before exocytosis and individual exocytotic events. 3. Quantitative optical analysis indicates that chromaffin granule motion is highly restricted but regulated. Granules can undergo significant motion in the 100 ms prior to fusion and interactions with the plasma membrane leading to fusion can occur within this time. The small motions may permit granules adjacent to the plasma membrane to repetitively sample microdomains of the plasma membrane, thereby increasing the probability of fruitful interactions that lead to fusion.

  19. Redistribution of fluorescent molecules at the solid/liquid interface with total internal reflection illumination.

    PubMed

    Wei, Lin; Ye, Zhongju; Luo, Wenjuan; Chen, Bo; Xiao, Lehui

    2016-08-01

    Many intriguing physical and chemical processes commonly take place at the solid/liquid interface. Total internal reflection illumination, together with single molecule spectroscopy, provides a robust platform for the selective exploration of kinetic processes close the interface. With these techniques, it was observed that the distribution of Rhodamine B molecules close to a solid/liquid interface could be regulated in a photo-induced route. The laser-induced repulsion force at this interface is enough to compromise the Brownian diffusion of single molecules in a range of several hundred nanometers normal to the solid/liquid interface. This observation is fundamentally and practically interesting because moderate laser intensity is enough to initiate this repulsion effect. Therefore, it might display extensive applications in the development of photo-modulation technique with high throughput capability.

  20. Analysis of total oil and fatty acids composition by near infrared reflectance spectroscopy in edible nuts

    NASA Astrophysics Data System (ADS)

    Kandala, Chari V.; Sundaram, Jaya

    2014-10-01

    Near Infrared (NIR) Reflectance spectroscopy has established itself as an important tool in quantifying water and oil present in various food materials. It is rapid and nondestructive, easier to use, and does not require processing the samples with corrosive chemicals that would render them non-edible. Earlier, the samples had to be ground into powder form before making any measurements. With the development of new soft ware packages, NIR techniques could now be used in the analysis of intact grain and nuts. While most of the commercial instruments presently available work well with small grain size materials such as wheat and corn, the method present here is suitable for large kernel size products such as shelled or in-shell peanuts. Absorbance spectra were collected from 400 nm to 2500 nm using a NIR instrument. Average values of total oil contents (TOC) of peanut samples were determined by standard extraction methods, and fatty acids were determined using gas chromatography. Partial least square (PLS) analysis was performed on the calibration set of absorption spectra, and models were developed for prediction of total oil and fatty acids. The best model was selected based on the coefficient of determination (R2), Standard error of prediction (SEP) and residual percent deviation (RPD) values. Peanut samples analyzed showed RPD values greater than 5.0 for both absorbance and reflectance models and thus could be used for quality control and analysis. Ability to rapidly and nondestructively measure the TOC, and analyze the fatty acid composition, will be immensely useful in peanut varietal improvement as well as in the grading process of grain and nuts.

  1. Immunoglobulin surface-binding kinetics studied by total internal reflection with fluorescence correlation spectroscopy.

    PubMed Central

    Thompson, N L; Axelrod, D

    1983-01-01

    An experimental application of total internal reflection with fluorescence correlation spectroscopy (TIR/FCS) is presented. TIR/FCS is a new technique for measuring the binding and unbinding rates and surface diffusion coefficient of fluorescent-labeled solute molecules in equilibrium at a surface. A laser beam totally internally reflects at the solid-liquid interface, selectively exciting surface-adsorbed molecules. Fluorescence collected by a microscope from a small, well-defined surface area approximately 5 micron2 spontaneously fluctuates as solute molecules randomly bind to, unbind from, and/or diffuse along the surface in chemical equilibrium. The fluorescence is detected by a photomultiplier and autocorrelated on-line by a minicomputer. The shape of the autocorrelation function depends on the bulk and surface diffusion coefficients, the binding rate constants, and the shape of the illuminated and observed region. The normalized amplitude of the autocorrelation function depends on the average number of molecules bound within the observed area. TIR/FCS requires no spectroscopic or thermodynamic change between dissociated and complexed states and no extrinsic perturbation from equilibrium. Using TIR/FCS, we determine that rhodamine-labeled immunoglobulin and insulin each nonspecifically adsorb to serum albumin-coated fused silica with both reversible and irreversible components. The characteristic time of the most rapidly reversible component measured is approximately 5 ms and is limited by the rate of bulk diffusion. Rhodamine-labeled bivalent antibodies to dinitrophenyl (DNP) bind to DNP-coated fused silica virtually irreversibly. Univalent Fab fragments of these same antibodies appear to specifically bind to DNP-coated fused silica, accompanied by a large amount of nonspecific binding. TIR/FCS is shown to be a feasible technique for measuring absorption/desorption kinetic rates at equilibrium. In suitable systems where nonspecific binding is low, TIR

  2. Carvacrol attenuates serum levels of total protein, phospholipase A2 and histamine in asthmatic guinea pig

    PubMed Central

    Boskabady, Mohammad Hossein; Jalali, Sedigheh; Yahyazadeh, Negin; Boskabady, Mostafa

    2016-01-01

    Objective: Pharmacological effects of carvacrol such as its anti-inflammatory activities have been shows. In this study the effects of carvacrol on serum levels of total protein (TP), phospholipase A2 (PLA2) and histamine in sensitized guinea pigs was evaluated. Materials and Methods: Sensitized guinea pigs were given drinking water alone (group S), drinking water containing three concentrations of carvacrol (40, 80 and 160 µg/ml) or dexamethasone. Serum levels of TP, PLA2 and histamine were examined I all sensitized groups as well as a non-sensitized control group (n=6 for each group). Results: In sensitized animals, serum levels of TP, PLA2 and histamine were significantly increased compared to control animals (p<0.05 to p<0.001). Significant reduction in TP, PLA2 and histamine levels were observed in treated groups with the two higher concentrations of carvacrol but dexamethasone treatment only decreased serum level of PLA2 (p<0.05 to p<0.001). Although the effect of the lowest concentration of the extract was less than that of dexamethasone (p<0.05 for TP and p<0.001 for PLA2), the effects of the two higher concentrations on PLA2 were similar to dexamethasone and on TP (p<0.01) and histamine (p<0.001) were higher than those of dexamethasone. Conclusion: These results showed that carvacrol reduced serum levels of TP, PLA2 and histamine in sensitized guinea pigs which may indicate an anti-inflammatory effect of this agent in inflammatory disorders such as asthma. PMID:28078244

  3. The Mixture of Salvianolic Acids from Salvia miltiorrhiza and Total Flavonoids from Anemarrhena asphodeloides Attenuate Sulfur Mustard-Induced Injury.

    PubMed

    Li, Jianzhong; Chen, Linlin; Wu, Hongyuan; Lu, Yiming; Hu, Zhenlin; Lu, Bin; Zhang, Liming; Chai, Yifeng; Zhang, Junping

    2015-10-15

    Sulfur mustard (SM) is a vesicating chemical warfare agent used in numerous military conflicts and remains a potential chemical threat to the present day. Exposure to SM causes the depletion of cellular antioxidant thiols, mainly glutathione (GSH), which may lead to a series of SM-associated toxic responses. MSTF is the mixture of salvianolic acids (SA) of Salvia miltiorrhiza and total flavonoids (TFA) of Anemarrhena asphodeloides. SA is the main water-soluble phenolic compound in Salvia miltiorrhiza. TFA mainly includes mangiferin, isomangiferin and neomangiferin. SA and TFA possess diverse activities, including antioxidant and anti-inflammation activities. In this study, we mainly investigated the therapeutic effects of MSTF on SM toxicity in Sprague Dawley rats. Treatment with MSTF 1 h after subcutaneous injection with 3.5 mg/kg (equivalent to 0.7 LD50) SM significantly increased the survival levels of rats and attenuated the SM-induced morphological changes in the testis, small intestine and liver tissues. Treatment with MSTF at doses of 60 and 120 mg/kg caused a significant (p<0.05) reversal in SM-induced GSH depletion. Gene expression profiles revealed that treatment with MSTF had a dramatic effect on gene expression changes caused by SM. Treatment with MSTF prevented SM-induced differential expression of 93.8% (973 genes) of 1037 genes. Pathway enrichment analysis indicated that these genes were mainly involved in a total of 36 pathways, such as the MAPK signaling pathway, pathways in cancer, antigen processing and presentation. These data suggest that MSTF attenuates SM-induced injury by increasing GSH and targeting multiple pathways, including the MAPK signaling pathway, as well as antigen processing and presentation. These results suggest that MSTF has the potential to be used as a potential therapeutic agent against SM injuries.

  4. Sensitivity Studies for Space-based Measurements of Atmospheric Total Column Carbon Dioxide Using Reflected Sunlight

    NASA Technical Reports Server (NTRS)

    Mao, Jianping; Kawa, S. Randolph

    2003-01-01

    A series of sensitivity studies is carried out to explore the feasibility of space-based global carbon dioxide (CO2) measurements for global and regional carbon cycle studies. The detection method uses absorption of reflected sunlight in the CO2 vibration-rotation band at 1.58 micron. The sensitivities of the detected radiances are calculated using the line-by-line model (LBLRTM), implemented with the DISORT (Discrete Ordinates Radiative Transfer) model to include atmospheric scattering in this band. The results indicate that (a) the small (approx.1%) changes in CO2 near the Earth's surface are detectable in this CO2 band provided adequate sensor signal-to-noise ratio and spectral resolution are achievable; (b) the effects of other interfering constituents, such as water vapor, aerosols and cirrus clouds, on the radiance are significant but the overall effects of the modification of light path length on total back-to-space radiance sensitivity to CO2 change are minor for general cases, which means that generally the total column CO2 can be derived in high precision from the ratio of the on-line center to off-line radiances; (c) together with CO2 gas absorption aerosol/cirrus cloud layer has differential scattering which may result in the modification of on-line to off-line radiance ratio which could lead a large bias in the total column CO2 retrieval. Approaches to correct such bias need further investigation. (d) CO2 retrieval requires good knowledge of the atmospheric temperature profile, e.g. approximately 1K RMS error in layer temperature, which is achievable from new atmospheric sounders in the near future; (e) the atmospheric path length, over which the CO2 absorption occurs, should be known in order to correctly interpret horizontal gradients of CO2 from the total column CO2 measurement; thus an additional sensor for surface pressure measurement needs to be attached for a complete measurement package.

  5. Sensitivity Studies for Space-based Measurements of Atmospheric Total Column Carbon Dioxide Using Reflected Sunlight

    NASA Technical Reports Server (NTRS)

    Mao, Jianping; Kawa, S. Randolph

    2003-01-01

    A series of sensitivity studies is carried out to explore the feasibility of space-based global carbon dioxide (CO2) measurements for global and regional carbon cycle studies. The detection method uses absorption of reflected sunlight in the CO2 vibration-rotation band at 1.58 micron. The sensitivities of the detected radiances are calculated using the line-by-line model (LBLRTM), implemented with the DISORT (Discrete Ordinates Radiative Transfer) model to include atmospheric scattering in this band. The results indicate that (a) the small (approx.1%) changes in CO2 near the Earth's surface are detectable in this CO2 band provided adequate sensor signal-to-noise ratio and spectral resolution are achievable; (b) the effects of other interfering constituents, such as water vapor, aerosols and cirrus clouds, on the radiance are significant but the overall effects of the modification of light path length on total back-to-space radiance sensitivity to CO2 change are minor for general cases, which means that generally the total column CO2 can be derived in high precision from the ratio of the on-line center to off-line radiances; (c) together with CO2 gas absorption aerosol/cirrus cloud layer has differential scattering which may result in the modification of on-line to off-line radiance ratio which could lead a large bias in the total column CO2 retrieval. Approaches to correct such bias need further investigation. (d) CO2 retrieval requires good knowledge of the atmospheric temperature profile, e.g. approximately 1K RMS error in layer temperature, which is achievable from new atmospheric sounders in the near future; (e) the atmospheric path length, over which the CO2 absorption occurs, should be known in order to correctly interpret horizontal gradients of CO2 from the total column CO2 measurement; thus an additional sensor for surface pressure measurement needs to be attached for a complete measurement package.

  6. Total reflection x-ray fluorescence: Determination of an optimum geometry

    SciTech Connect

    Koo, Y.M.; Chang, C.H.; Padmore, H.A.

    1997-04-01

    Total reflection X-Ray Fluorescence (TXRF) is a widely used technique in which the normal trace element detection capability of hard x-ray fluorescence (XRF) is enhanced by use of an x-ray reflective substrate. TXRF is more sensitive than normal photon induced XRF due to the reduction of the substrate scattering and fluorescence signals. This reduction comes about because in total external reflection, the photon field only penetrates about 20 {angstrom} into the surface, instead of typically 50 {mu}m for a silicon substrate at normal incidence for 10 KeV photons. The technique is used in many fields of trace element analysis, and is widely used in the determination of metal impurity concentrations on and in the surface of silicon wafers. The Semiconductor Industry Association roadmap (SIA) indicates a need for wafer contamination detection at the 10{sup 7}atoms/cm{sup 2} level in the next few years. Current commercial systems using rotating anode x-ray sources presently routinely operate with a sensitivity level of around 10{sup 10} atoms/cm{sup 2} and this has led to interest in the use of synchrotron radiation to extend the sensitivity by three orders of magnitude. The pioneering work of Pianetta and co-workers at SSRL has clearly shown that this should be possible, using a fully optimized source and detector. The purpose of this work is to determine whether ALS would be a suitable source for this type of highly sensitive wafer TXRF. At first look it appears improbable as the SSRL work used a high flux multipole wiggler source, and it is clear that the detected fluorescence for relevant concentrations is small. In addition, SSRL operates at 3.0 GeV rather than 1.9 GeV, and is therefore more naturally suited to hard x-ray experiments. The aim of this work was therefore to establish a theoretical model for the scattering and fluorescence processes, so that one could predict the differences between alternative geometries and select an optimum configuration.

  7. Production of the ideal sample shape for Total Reflection X-ray Fluorescence analysis

    NASA Astrophysics Data System (ADS)

    Horntrich, C.; Kregsamer, P.; Prost, J.; Stadlbauer, F.; Wobrauschek, P.; Streli, C.

    2012-11-01

    Total Reflection X-ray Fluorescence analysis (TXRF) is a well-established analytical method in the semiconductor industry for the analysis of silicon wafer surfaces. For the calibration of the spectrometer typically an external standard is used which is sensitive to quantification errors. In general TXRF is known to allow for linear calibration. For small sample amounts (pg to ng region) the thin film approximation is valid neglecting absorption effects of the exciting and the detected radiation. For higher total amounts of sample the relation between fluorescence intensity and sample amount diverges from linearity (saturation effect). These deviations lead to difficulties in quantification with external standard. Content of the presented work is the production of the ideal TXRF sample shape, which was theoretically determined to be ring shaped. A possibility for the production of samples with ring shape is the use of a nanodispensing system combined with a positioning device. Therewith it is possible to produce ring shaped samples in a controlled way with the ring consisting of individual nanodroplets, so that the wanted diameter of the ring can be chosen. A comparison of the fluorescence intensities emitted by contracted and ring shaped samples shows that the ring shape is not only theoretically the best TXRF shape but also experimentally. It could be proven that for contracted samples the saturation effect occurs at a lower sample mass than for samples with ring shape.

  8. Determination of carbon in natural freshwater biofilms with total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Óvári, M.; Streli, C.; Wobrauschek, P.; Záray, Gy.

    2009-08-01

    There is a growing interest in determination of low Z elements, i.e., carbon to phosphorus, in biological samples. Total reflection X-ray fluorescence spectrometry (TXRF) has been already established as suitable trace element analytical method with low sample demand and quite good quantification limits. Recently, the determinable element range was extended towards Z = 6 (carbon). Biofilms can be used for biomonioring purposes in the aquatic environment. Besides the trace metals, especially the determination of the carbon content is important for the better understanding of the early stage of biofilm formation. For this, an ATI low Z spectrometer equipped with Cr-anode X-ray tube, multilayer monochromator, vacuum chamber, and a Si(Li) detector with ultra thin window was used. Biofilms were grown on two different artificial supports (granite and plexiglass), freeze dried, suspended in high purity water and analyzed. As an internal standard the natural titanium content of the biofilms was used. The accuracy of the method was checked by total carbon measurement using a combusting carbon analyzer.

  9. Developing a composite weighted quality metric to reflect the total benefit conferred by a health plan.

    PubMed

    Taskler, Glen B; Braithwaite, R Scott

    2015-03-01

    To improve individual health quality measures, which are associated with varying degrees of health benefit, and composite quality metrics, which weight individual measures identically. We developed a health-weighted composite quality measure reflecting the total health benefit conferred by a health plan annually, using preventive care as a test case. Using national disease prevalence, we simulated a hypothetical insurance panel of individuals aged 25 to 84 years. For each individual, we estimated the gain in life expectancy associated with 1 year of health system exposure to encourage adherence to major preventive care guidelines, controlling for patient characteristics (age, race, gender, comorbidity) and variation in individual adherence rates. This personalized gain in life expectancy was used to proxy for the amount of health benefit conferred by a health plan annually to its members, and formed weights in our health-weighted composite quality measure. We aggregated health benefits across the health insurance membership panel to analyze total health system performance. Our composite quality metric gave the highest weights to health plans that succeeded in implementing tobacco cessation and weight loss. One year of compliance with these goals was associated with 2 to 10 times as much health benefit as compliance with easier-to-follow preventive care services, such as mammography, aspirin, and antihypertensives. For example, for women aged 55 to 64 years, successful interventions to encourage weight loss were associated with 2.1 times the health benefit of blood pressure reduction and 3.9 times the health benefit of increasing adherence with screening mammography. A single health-weighted quality metric may inform measurement of total health system performance.

  10. Structural Health Monitoring Using Lamb Wave Reflections and Total Focusing Method for Image Reconstruction

    NASA Astrophysics Data System (ADS)

    Muller, Aurelia; Robertson-Welsh, Bradley; Gaydecki, Patrick; Gresil, Matthieu; Soutis, Constantinos

    2016-11-01

    This investigation aimed to adapt the total focusing method (TFM) algorithm (originated from the synthetic aperture focusing technique in digital signal processing) to accommodate a circular array of piezoelectric sensors (PZT) and characterise defects using guided wave signals for the development of a structural health monitoring system. This research presents the initial results of a broader study focusing on the development of a structural health monitoring (SHM) guided wave system for advance carbon fibre reinforced plastic (CFRP) composite materials. The current material investigated was an isotropic (aluminium) square plate with 16 transducers operating successively as emitter or sensor in pitch and catch configuration enabling the collection of 240 signals per assessment. The Lamb wave signals collected were tuned on the symmetric fundamental mode with a wavelength of 17 mm, by setting the excitation frequency to 300 kHz. The initial condition for the imaging system, such as wave speed and transducer position, were determined with post processing of the baseline signals through a method involving the identification of the waves reflected from the free edge of the plate. The imaging algorithm was adapted to accommodate multiple transmitting transducers in random positions. A circular defect of 10 mm in diameter was drilled in the plate, which is similar to the delamination size introduced by a low velocity impact event in a composite plate. Images were obtained by applying the TFM to the baseline signals, Test 1 data (corresponding to the signals obtained after introduction of the defect) and to the data derived from the subtraction of the baseline to the Test 1 signals. The result shows that despite the damage diameter being 40 % smaller than the wavelength, the image (of the subtracted baseline data) demonstrated that the system can locate where the waves were reflected from the defect boundary. In other words, the contour of the damaged area was

  11. An active one-particle microrheometer: incorporating magnetic tweezers to total internal reflection microscopy.

    PubMed

    Gong, Xiangjun; Hua, Li; Wu, Chi; Ngai, To

    2013-03-01

    We present a novel microrheometer by incorporating magnetic tweezers in the total internal reflection microscopy (TIRM) that enables measuring of viscoelastic properties of materials near solid surface. An evanescent wave generated by a solid∕liquid interface in the TIRM is used as the incident light source in the microrheometer. When a probe particle (of a few micrometers diameter) moves near the interface, it can interact with the evanescent field and reflect its position with respect to the interface by the scattered light intensity. The exponential distance dependence of the evanescent field, on the one hand, makes this technique extremely sensitive to small changes from z-fluctuations of the probe (with a resolution of several nanometers), and on the other, it does not require imaging of the probe with high lateral resolution. Another distinct advantage is the high sensitivity in determining the z position of the probe in the absence of any labeling. The incorporated magnetic tweezers enable us to effectively manipulate the distance of the embedded particle from the interface either by a constant or an oscillatory force. The force ramp is easy to implement through a coil current ramp. In this way, the local viscous and elastic properties of a given system under different confinements can therefore be measured by resolving the near-surface particle motion. To test the feasibility of applying this microrheology to soft materials, we measured the viscoelastic properties of sucrose and poly(ethylene glycol) solutions and compared the results to bulk rheometry. In addition, we applied this technique in monitoring the structure and properties of deformable microgel particles near the flat surface.

  12. Structural Health Monitoring Using Lamb Wave Reflections and Total Focusing Method for Image Reconstruction

    NASA Astrophysics Data System (ADS)

    Muller, Aurelia; Robertson-Welsh, Bradley; Gaydecki, Patrick; Gresil, Matthieu; Soutis, Constantinos

    2017-04-01

    This investigation aimed to adapt the total focusing method (TFM) algorithm (originated from the synthetic aperture focusing technique in digital signal processing) to accommodate a circular array of piezoelectric sensors (PZT) and characterise defects using guided wave signals for the development of a structural health monitoring system. This research presents the initial results of a broader study focusing on the development of a structural health monitoring (SHM) guided wave system for advance carbon fibre reinforced plastic (CFRP) composite materials. The current material investigated was an isotropic (aluminium) square plate with 16 transducers operating successively as emitter or sensor in pitch and catch configuration enabling the collection of 240 signals per assessment. The Lamb wave signals collected were tuned on the symmetric fundamental mode with a wavelength of 17 mm, by setting the excitation frequency to 300 kHz. The initial condition for the imaging system, such as wave speed and transducer position, were determined with post processing of the baseline signals through a method involving the identification of the waves reflected from the free edge of the plate. The imaging algorithm was adapted to accommodate multiple transmitting transducers in random positions. A circular defect of 10 mm in diameter was drilled in the plate, which is similar to the delamination size introduced by a low velocity impact event in a composite plate. Images were obtained by applying the TFM to the baseline signals, Test 1 data (corresponding to the signals obtained after introduction of the defect) and to the data derived from the subtraction of the baseline to the Test 1 signals. The result shows that despite the damage diameter being 40 % smaller than the wavelength, the image (of the subtracted baseline data) demonstrated that the system can locate where the waves were reflected from the defect boundary. In other words, the contour of the damaged area was

  13. Direct experimental observation of giant Goos-Hänchen shifts from bandgap-enhanced total internal reflection.

    PubMed

    Wan, Yuhang; Zheng, Zheng; Kong, Weijing; Liu, Ya; Lu, Zhiting; Bian, Yusheng

    2011-09-15

    Giant Goos-Hänchen (GH) shifts are experimentally demonstrated from a prism-coupled multilayer structure incorporating a one-dimensional photonic crystal (PC) through a bandgap-enhanced total internal reflection scheme. By combining the large phase changes near the bandgap of the PC and the low reflection loss of the total internal reflection, 2 orders of magnitude enhancement of the GH shift is realized with rather low extra optical loss, which might help to open the door toward many interesting applications for GH effects.

  14. Total internal reflection fluorescence microscopy for determination of size of individual immobilized vesicles: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Olsson, Thomas; Zhdanov, Vladimir P.; Höök, Fredrik

    2015-08-01

    Lipid vesicles immobilized via molecular linkers at a solid support represent a convenient platform for basic and applied studies of biological processes occurring at lipid membranes. Using total internal reflection fluorescence microscopy (TIRFM), one can track such processes at the level of individual vesicles provided that they contain dyes. In such experiments, it is desirable to determine the size of each vesicle, which may be in the range from 50 to 1000 nm. Fortunately, TIRFM in combination with nanoparticle tracking analysis makes it possible to solve this problem as well. Herein, we present the formalism allowing one to interpret the TIRFM measurements of the latter category. The analysis is focused primarily on the case of unpolarized light. The specifics of the use of polarized light are also discussed. In addition, we show the expected difference in size distribution of suspended and immobilized vesicles under the assumption that the latter ones are deposited under diffusion-controlled conditions. In the experimental part of our work, we provide representative results, showing explicit advantages and some shortcomings of the use of TIRFM in the context under consideration, as well as how our refined formalism improves previously suggested approaches.

  15. Design and construction of a multiwavelength, micromirror total internal reflectance fluorescence microscope.

    PubMed

    Larson, Joshua; Kirk, Matt; Drier, Eric A; O'Brien, William; MacKay, James F; Friedman, Larry J; Hoskins, Aaron A

    2014-10-01

    Colocalization single-molecule spectroscopy (CoSMoS) has proven to be a useful method for studying the composition, kinetics and mechanisms of complex cellular machines. Key to the technique is the ability to simultaneously monitor multiple proteins and/or nucleic acids as they interact with one another. Here we describe a protocol for constructing a CoSMoS micromirror total internal reflection fluorescence microscope (mmTIRFM). Design and construction of a scientific microscope often requires a number of custom components and a substantial time commitment. In our protocol, we have streamlined this process by implementation of a commercially available microscopy platform designed to accommodate the optical components necessary for an mmTIRFM. The mmTIRF system eliminates the need for machining custom parts by the end user and facilitates optical alignment. Depending on the experience level of the microscope builder, these time savings and the following protocol can enable mmTIRF construction to be completed within 2 months.

  16. A total internal reflection-fluorescence correlation spectroscopy setup with pulsed diode laser excitation

    NASA Astrophysics Data System (ADS)

    Weger, Lukas; Hoffmann-Jacobsen, Kerstin

    2017-09-01

    Fluorescence correlation spectroscopy (FCS) measures fluctuations in a (sub-)femtoliter volume to analyze the diffusive behavior of fluorescent particles. This highly sensitive method has proven to be useful for the analysis of dynamic biological systems as well as in chemistry, physics, and material sciences. It is routinely performed with commercial fluorescence microscopes, which provide a confined observation volume by the confocal technique. The evanescent wave of total internal reflectance (TIR) is used in home-built systems to permit a surface sensitive FCS analysis. We present a combined confocal and TIR-FCS setup which uses economic low-power pulsed diode lasers for excitation. Excitation and detection are coupled to time-correlated photon counting hardware. This allows simultaneous fluorescence lifetime and FCS measurements in a surface-sensitive mode. Moreover, the setup supports fluorescence lifetime correlation spectroscopy at surfaces. The excitation can be easily switched between TIR and epi-illumination to compare the surface properties with those in liquid bulk. The capabilities of the presented setup are demonstrated by measuring the diffusion coefficients of a free dye molecule, a labeled polyethylene glycol, and a fluorescent nanoparticle in confocal as well as in TIR-FCS.

  17. The polarized total internal reflection fluorescence microscopy (polTIRFM) twirling filament assay.

    PubMed

    Beausang, John F; Sun, Yujie; Quinlan, Margot E; Forkey, Joseph N; Goldman, Yale E

    2012-06-01

    Polarized total internal reflection fluorescence microscopy (polTIRFM) can be used to detect the spatial orientation and rotational dynamics of single molecules. polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. This protocol describes the twirling filament assay, so named because actin sometimes twirls about its own axis as it is translocated by myosin. A gliding filament assay is constructed in which a sparsely labeled actin filament (0.3% of the actin monomers contain 6'- iodoacetamidotetramethylrhodamine [IATR]) is translocated by a field of unlabeled myosin V fixed to the surface. The polTIRFM twirling assay differs from a standard gliding filament assay in that full filaments are not visible, but rather individual fluorophores are spaced along each filament. The goal is to investigate possible rotational motions of the actin filament about its axis (i.e., twirling) by measuring the spatial angle of the fluorescent probe as a function of time. Successful assays contain microscopic fields of approximately 50 isolated points of fluorescence that move across the field in the presence of ATP. Actin is usually translocated by more than one myosin molecule, depending on the filament length and the myosin surface density. Sparsely labeled filaments are required because the orientation of only one probe can be resolved at a time.

  18. Elucidation of perovskite film micro-orientations using two-photon total internal reflectance fluorescence microscopy

    DOE PAGES

    Watson, Brianna R.; Yang, Bin; Xiao, Kai; ...

    2015-07-29

    The emergence of efficient hybrid organic-inorganic perovskite photovoltaic materials has caused the rapid development of a variety of preparation and processing techniques designed to maximize their performance. As processing methods continue to emerge, it is important to understand how the optical properties of these materials are affected on a microscopic scale. Here polarization resolved two-photon total internal reflectance microscopy (TIRFM) was used to probe changes in transition dipole moment orientation as a function of thermal annealing time in hybrid organic-inorganic lead iodide based perovskite (CH3NH3PbI3) thin films on glass. These results show that as thermal annealing time is increased themore » distribution of transition moments pointing out-of-plane decreases in favor of forming areas with increased in-plane orientations. As a result, it was also shown through the axial sensitivity of TIRFM that the surface topography is manifested in the signal intensity and can be used to survey aspects of morphology in coincidence with the optical properties of these films.« less

  19. Elucidation of perovskite film micro-orientations using two-photon total internal reflectance fluorescence microscopy

    SciTech Connect

    Watson, Brianna R.; Yang, Bin; Xiao, Kai; Ma, Ying -Zhong; Doughty, Benjamin L.; Calhoun, Tessa R.

    2015-07-29

    The emergence of efficient hybrid organic-inorganic perovskite photovoltaic materials has caused the rapid development of a variety of preparation and processing techniques designed to maximize their performance. As processing methods continue to emerge, it is important to understand how the optical properties of these materials are affected on a microscopic scale. Here polarization resolved two-photon total internal reflectance microscopy (TIRFM) was used to probe changes in transition dipole moment orientation as a function of thermal annealing time in hybrid organic-inorganic lead iodide based perovskite (CH3NH3PbI3) thin films on glass. These results show that as thermal annealing time is increased the distribution of transition moments pointing out-of-plane decreases in favor of forming areas with increased in-plane orientations. As a result, it was also shown through the axial sensitivity of TIRFM that the surface topography is manifested in the signal intensity and can be used to survey aspects of morphology in coincidence with the optical properties of these films.

  20. A Platform for Combined DNA and Protein Microarrays Based on Total Internal Reflection Fluorescence

    PubMed Central

    Asanov, Alexander; Zepeda, Angélica; Vaca, Luis

    2012-01-01

    We have developed a novel microarray technology based on total internal reflection fluorescence (TIRF) in combination with DNA and protein bioassays immobilized at the TIRF surface. Unlike conventional microarrays that exhibit reduced signal-to-background ratio, require several stages of incubation, rinsing and stringency control, and measure only end-point results, our TIRF microarray technology provides several orders of magnitude better signal-to-background ratio, performs analysis rapidly in one step, and measures the entire course of association and dissociation kinetics between target DNA and protein molecules and the bioassays. In many practical cases detection of only DNA or protein markers alone does not provide the necessary accuracy for diagnosing a disease or detecting a pathogen. Here we describe TIRF microarrays that detect DNA and protein markers simultaneously, which reduces the probabilities of false responses. Supersensitive and multiplexed TIRF DNA and protein microarray technology may provide a platform for accurate diagnosis or enhanced research studies. Our TIRF microarray system can be mounted on upright or inverted microscopes or interfaced directly with CCD cameras equipped with a single objective, facilitating the development of portable devices. As proof-of-concept we applied TIRF microarrays for detecting molecular markers from Bacillus anthracis, the pathogen responsible for anthrax. PMID:22438738

  1. Frustrated total internal reflection in organic light-emitting diodes employing sphere cavity embedded in polystyrene

    NASA Astrophysics Data System (ADS)

    Zhu, Peifen

    2016-02-01

    The light extraction efficiency of top-emitting organic light-emitting diodes (OLEDs) is numerically investigated employing the finite-difference time-domain method. The periodic nanostructures formed by embedding the sphere arrays in polystyrene (PS) are placed on top of OLED to frustrate the total internal reflection at the interface between OLED and free space. These nanostructures serve as an intermediate medium to extract the light out of OLED devices. Efficiently coupling both evanescent waves and propagation waves into spheres and subsequently extracting these light waves out of the sphere is key to achieving high extraction efficiency. By tuning the thickness of PS layer, both of the in-coupling efficiency and out-coupling efficiency are optimized for achieving high light extraction efficiency. Thicker PS layer results in higher in-coupling efficiency in sphere while the thinner PS layer leads to higher out-coupling efficiency. Thus the maximum light extraction is a trade-off between the in-coupling efficiency and out-coupling efficiency. The study shows that light extraction efficiency of 89% can be achieved by embedding 0.90 μm TiO2 sphere in 0.30 μm PS layer with optimized in-coupling efficiency, out-coupling efficiency and cavity effect.

  2. Total internal reflection photoacoustic spectroscopy for the detection of β-hematin

    NASA Astrophysics Data System (ADS)

    Goldschmidt, Benjamin S.; Sudduth, Amanda S. M.; Samson, Edward B.; Whiteside, Paul J. D.; Bhattacharyya, Kiran D.; Viator, John A.

    2012-06-01

    Evanescent field sensing methods are currently used to detect many different types of disease markers and biologically important chemicals such as the HER2 breast cancer receptor. Hinoue et al. used Total Internal Reflection Photoacoustic Spectroscopy (TIRPAS) as a method of using the evanescent field to detect an optically opaque dye at a sample interface. Although their methods were successful at detecting dyes, the results at that time did not show a very practical spectroscopic technique, which was due to the less than typical sensitivity of TIRPAS as a spectroscopy modality given the low power (~1 to 2 W) lasers being used. Contrarily, we have used an Nd:YAG laser with a five nanosecond pulse that gives peak power of 1 MW coupled with the TIRPAS system to increase the sensitivity of this technique for biological material sensing. All efforts were focused on the eventual detection of the optically absorbing material, hemozoin, which is created as a byproduct of a malarial infection in blood. We used an optically analogous material, β-hematin, to determine the potential for detection in the TIRPAS system. In addition, four properties which control the sensitivity were investigated to increase understanding about the sensor's function as a biosensing method.

  3. High pressure sample cell for total internal reflection fluorescence spectroscopy at pressures up to 2500 bar

    NASA Astrophysics Data System (ADS)

    Koo, Juny; Czeslik, Claus

    2012-08-01

    Total internal reflection fluorescence (TIRF) spectroscopy is a surface sensitive technique that is widely used to characterize the structure and dynamics of molecules at planar liquid-solid interfaces. In particular, biomolecular systems, such as protein adsorbates and lipid membranes can easily be studied by TIRF spectroscopy. Applying pressure to molecular systems offers access to all kinds of volume changes occurring during assembly of molecules, phase transitions, and chemical reactions. So far, most of these volume changes have been characterized in bulk solution, only. Here, we describe the design and performance of a high pressure sample cell that allows for TIRF spectroscopy under high pressures up to 2500 bar (2.5 × 108 Pa), in order to expand the understanding of volume effects from the bulk phase to liquid-solid interfaces. The new sample cell is based on a cylindrical body made of Nimonic 90 alloy and incorporates a pressure transmitting sample cuvette. This cuvette is composed of a fused silica prism and a flexible rubber gasket. It contains the sample solution and ensures a complete separation of the sample from the liquid pressure medium. The sample solution is in contact with the inner wall of the prism forming the interface under study, where fluorescent molecules are immobilized. In this way, the new high pressure TIRF sample cell is very useful for studying any biomolecular layer that can be deposited at a planar water-silica interface. As examples, high pressure TIRF data of adsorbed lysozyme and two phospholipid membranes are presented.

  4. Determination of element levels in human serum: Total reflection X-ray fluorescence applications

    NASA Astrophysics Data System (ADS)

    Majewska, U.; Łyżwa, P.; Łyżwa, K.; Banaś, D.; Kubala-Kukuś, A.; Wudarczyk-Moćko, J.; Stabrawa, I.; Braziewicz, J.; Pajek, M.; Antczak, G.; Borkowska, B.; Góźdź, S.

    2016-08-01

    Deficiency or excess of elements could disrupt proper functioning of the human body and could lead to several disorders. Determination of their concentrations in different biological human fluids and tissues should become a routine practice in medical treatment. Therefore the knowledge about appropriate element concentrations in human organism is required. The purpose of this study was to determine the concentration of several elements (P, S, Cl, K, Ca, Cr, Fe, Cu, Zn, Se, Br, Rb, Pb) in human serum and to define the reference values of element concentration. Samples of serum were obtained from 105 normal presumably healthy volunteers (66 women aged between 15 and 78 years old; 39 men aged between 15 and 77 years old). Analysis has been done for the whole studied population and for subgroups by sex and age. It is probably first so a wide study of elemental composition of serum performed in the case of Świętokrzyskie region. Total reflection X-ray fluorescence (TXRF) method was used to perform the elemental analysis. Spectrometer S2 Picofox (Bruker AXS Microanalysis GmbH) was used to identify and measure elemental composition of serum samples. Finally, 1st and 3rd quartiles were accepted as minimum and maximum values of concentration reference range.

  5. Total reflection X-ray fluorescence as a fast multielemental technique for human placenta sample analysis

    NASA Astrophysics Data System (ADS)

    Marguí, E.; Ricketts, P.; Fletcher, H.; Karydas, A. G.; Migliori, A.; Leani, J. J.; Hidalgo, M.; Queralt, I.; Voutchkov, M.

    2017-04-01

    In the present contribution, benchtop total reflection X-ray fluorescence spectrometry (TXRF) has been evaluated as a cost-effective multielemental analytical technique for human placenta analysis. An easy and rapid sample preparation consisting of suspending 50 mg of sample in 1 mL of a Triton 1% solution in deionized water showed to be the most suitable for this kind of samples. However, for comparison purposes, an acidic microwave acidic digestion procedure was also applied. For both sample treatment methodologies, limits of detection for most elements were in the low mg/kg level. Accurate and precise results were obtained using internal standardization as quantification approach and applying a correction factor to compensate for absorption effects. The correction factor was based on the proportional ratio between the slurry preparation results and those obtained for the analysis of a set of human placenta samples analysed by microwave acidic digestion and ICP-AES analysis. As a study case, the developed TXRF methodology was applied for multielemental analysis (K, Ca, Fe, Cu, Zn, As, Se, Br, Rb and Sr) of several healthy women's placenta samples from two regions in Jamaica.

  6. Rainwater analysis by synchrotron radiation-total reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    López, María L.; Ceppi, Sergio A.; Asar, María L.; Bürgesser, Rodrigo E.; Ávila, Eldo E.

    2015-11-01

    Total reflection X-ray fluorescence analysis excited with synchrotron radiation was used to quantify the elemental concentration of rainwater in Córdoba, Argentina. Standard solutions with gallium as internal standard were prepared for the calibration curves. Rainwater samples of 5 μl were added to an acrylic reflector, allowed to dry, and analyzed for 200 s measuring time. The elemental concentrations of As, Ca, Co, Cr, Cu, Fe, K, Mn, Ni, Pb, S, Sr, V, and Zn were determined. The electrical conductivity, pH, and elemental concentrations were compared to data previously reported for the soluble fraction of rainwater at different sites. A factor analysis was performed in order to determine the sources that contributed to the elemental concentration in rainwater. Anthropogenic sources were identified as traffic pollution, vehicular emissions, and metallurgical factories. The quality of rainwater was analyzed by comparing the concentrations of all the elements in rainwater samples with the WHO guideline values for drinking water. The results show the need to control the atmospheric emissions in order to preserve the quality of rainwater. SR-TXRF analysis of chemical composition of rainwater in Córdoba represents the very first contribution in the region to the knowledge of the concentration of trace metals in the soluble fraction of rainwater. These data are scarce, especially in the Southern Hemisphere.

  7. Glutathione immunosensing platform based on total internal reflection ellipsometry enhanced by functionalized gold nanoparticles.

    PubMed

    García-Marín, Antonio; Abad, José M; Ruiz, Eduardo; Lorenzo, Encarnación; Piqueras, Juan; Pau, José L

    2014-05-20

    An immunosensor to detect small molecules, such as glutathione (GSH), has been developed by combination of ellipsometry and Kretschmann surface plasmon resonance (SPR). The Au thin film used for surface plasmon polariton (SPP) excitation is functionalized with anti-GSH to specifically bind GSH. At low concentrations, the small refractive index changes caused by the low molecular weight of GSH induced only negligible shifts in the plasmon resonant energy during GSH binding. To improve sensitivity, gold nanoparticles (AuNPs) are functionalized with glutathione acting as amplifiers of the antigen-antibody interaction. Changes induced by the AuNP adsorption are monitored using Ψ and Δ ellipsometric functions. After performing competitive assays using solutions containing different concentrations of free GSH and a constant amount of functionalized AuNPs, it was concluded that the resonant energy linearly shifts as the relative concentration of free GSH increases. A detection limit for free GSH in the nanomolar range is found, demonstrating the effectiveness of AuNPs to enhance the sensitivity to immunoreactions in total internal reflection ellipsometry.

  8. Elemental concentration analysis in prostate tissues using total reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Leitão, R. G.; Palumbo, A.; Souza, P. A. V. R.; Pereira, G. R.; Canellas, C. G. L.; Anjos, M. J.; Nasciutti, L. E.; Lopes, R. T.

    2014-02-01

    Prostate cancer (PCa) currently represents the second most prevalent malignant neoplasia in men, representing 21% of all cancer cases. Benign Prostate Hyperplasia (BPH) is an illness prevailing in men above the age of 50, close to 90% after the age of 80. The prostate presents a high zinc concentration, about 10-fold higher than any other body tissue. In this work, samples of human prostate tissues with cancer, BPH and normal tissue were analyzed utilizing total reflection X-ray fluorescence spectroscopy using synchrotron radiation technique (SR-TXRF) to investigate the differences in the elemental concentrations in these tissues. SR-TXRF analyses were performed at the X-ray fluorescence beamline at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo. It was possible to determine the concentrations of the following elements: P, S, K, Ca, Fe, Cu, Zn and Rb. By using Mann-Whitney U test it was observed that almost all elements presented concentrations with significant differences (α=0.05) between the groups studied.

  9. Total reflection X-ray fluorescence as a tool for food screening

    NASA Astrophysics Data System (ADS)

    Borgese, Laura; Bilo, Fabjola; Dalipi, Rogerta; Bontempi, Elza; Depero, Laura E.

    2015-11-01

    This review provides a comprehensive overview of the applications of total reflection X-ray fluorescence (TXRF) in the field of food analysis. Elemental composition of food is of great importance, since food is the main source of essential, major and trace elements for animals and humans. Some potentially toxic elements, dangerous for human health may contaminate food, entering the food chain from the environment, processing, and storage. For this reason the elemental analysis of food is fundamental for safety assessment. Fast and sensitive analytical techniques, able to detect major and trace elements, are required as a result of the increasing demand on multi-elemental information and product screening. TXRF is suitable for elemental analysis of food, since it provides simultaneous multi-elemental identification in a wide dynamic range of concentrations. Several different matrices may be analyzed obtaining results with a good precision and accuracy. In this review, the most recent literature about the use of TXRF for the analysis of food is reported. The focus is placed on the applications within food quality monitoring of drinks, beverages, vegetables, fruits, cereals, animal derivatives and dietary supplements. Furthermore, this paper provides a critical outlook on the developments required to transfer these methods from research to the industrial and analytical laboratories contexts.

  10. Measuring incidence angle for through-the-objective total internal reflection fluorescence microscopy

    PubMed Central

    2012-01-01

    Abstract. Total internal reflection fluorescence (TIRF) microscopy has the exciting laser beam incident beyond critical angle from the glass side of a glass/aqueous interface formed by the coverslip and aqueous sample. The aqueous side evanescent field decays exponentially with distance from the interface with penetration depth depending on incidence angle. Through-the-objective TIRF has the exciting laser focused at the back focal plane (BFP) creating a refracted parallel beam approaching the interface in the small gap between objective and coverslip, making incidence angle challenging to measure. Objective axial scanning does not affect incidence angle but translates beam and interface intersection detected by the fluorescence center of mass from fluorescent spheres attached to the aqueous side of the interface. Center of mass translation divided by the axial translation is the tangent of the incidence angle that is sampled repeatedly over objective trajectory to obtain a best estimate. Incidence angle is measured for progressively larger radial positions of the focused beam on the BFP. A through-the-objective TIRF microscope, utilizing a micrometer and relay lenses to position the focused beam at the BFP, is calibrated for incidence angle. Calibration depends on microscope characteristics and TIRF objective and is applicable to any interface or sample. PMID:23208218

  11. Accessible biometrics: A frustrated total internal reflection approach to imaging fingerprints.

    PubMed

    Smith, Nathan D; Sharp, James S

    2017-05-01

    Fingerprints are widely used as a means of identifying persons of interest because of the highly individual nature of the spatial distribution and types of features (or minuta) found on the surface of a finger. This individuality has led to their wide application in the comparison of fingerprints found at crime scenes with those taken from known offenders and suspects in custody. However, despite recent advances in machine vision technology and image processing techniques, fingerprint evidence is still widely being collected using outdated practices involving ink and paper - a process that can be both time consuming and expensive. Reduction of forensic service budgets increasingly requires that evidence be gathered and processed more rapidly and efficiently. However, many of the existing digital fingerprint acquisition devices have proven too expensive to roll out on a large scale. As a result new, low-cost imaging technologies are required to increase the quality and throughput of the processing of fingerprint evidence. Here we describe an inexpensive approach to digital fingerprint acquisition that is based upon frustrated total internal reflection imaging. The quality and resolution of the images produced are shown to be as good as those currently acquired using ink and paper based methods. The same imaging technique is also shown to be capable of imaging powdered fingerprints that have been lifted from a crime scene using adhesive tape or gel lifters. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

  12. Quantifying the Assembly of Multicomponent Molecular Machines by Single-Molecule Total Internal Reflection Fluorescence Microscopy.

    PubMed

    Boehm, E M; Subramanyam, S; Ghoneim, M; Washington, M Todd; Spies, M

    2016-01-01

    Large, dynamic macromolecular complexes play essential roles in many cellular processes. Knowing how the components of these complexes associate with one another and undergo structural rearrangements is critical to understanding how they function. Single-molecule total internal reflection fluorescence (TIRF) microscopy is a powerful approach for addressing these fundamental issues. In this article, we first discuss single-molecule TIRF microscopes and strategies to immobilize and fluorescently label macromolecules. We then review the use of single-molecule TIRF microscopy to study the formation of binary macromolecular complexes using one-color imaging and inhibitors. We conclude with a discussion of the use of TIRF microscopy to examine the formation of higher-order (i.e., ternary) complexes using multicolor setups. The focus throughout this article is on experimental design, controls, data acquisition, and data analysis. We hope that single-molecule TIRF microscopy, which has largely been the province of specialists, will soon become as common in the tool box of biophysicists and biochemists as structural approaches have become today. © 2016 Elsevier Inc. All rights reserved.

  13. Extraction of light trapped due to total internal reflection using porous high refractive index nanoparticle films.

    PubMed

    Mao, Peng; Sun, Fangfang; Yao, Hanchao; Chen, Jing; Zhao, Bo; Xie, Bo; Han, Min; Wang, Guanghou

    2014-07-21

    TiO₂ nanoparticle layers composed of columnar TiO₂ nanoparticle piles separated with nanoscale pores were fabricated on the bottom surface of the hemispherical glass prism by performing gas phase cluster beam deposition at glancing incidence. The porosity as well as the refractive index of the nanoparticle layer was precisely tuned by the incident angle. Effective extraction of the light trapped in the substrate due to total internal reflection with the TiO₂ nanoparticle layers was demonstrated and the extraction efficiency was found to increase with the porosity. An enhanced Rayleigh scattering mechanism, which results from the columnar aggregation of the nanoparticles as well as the strong contrast in the refractive index between pores and TiO₂ nanoparticles in the nanoporous structures, was proposed. The porous TiO₂ nanoparticle coatings were fabricated on the surface of GaN LEDs to enhance their light output. A nearly 92% PL enhancement as well as a 30% EL enhancement was observed. For LED applications, the enhanced light extraction with the TiO₂ nanoparticle porous layers can be a supplement to the microscale texturing process for light extraction enhancement.

  14. New light on ion channel imaging by total internal reflection fluorescence (TIRF) microscopy.

    PubMed

    Yamamura, Hisao; Suzuki, Yoshiaki; Imaizumi, Yuji

    2015-05-01

    Ion channels play pivotal roles in a wide variety of cellular functions; therefore, their physiological characteristics, pharmacological responses, and molecular structures have been extensively investigated. However, the mobility of an ion channel itself in the cell membrane has not been examined in as much detail. A total internal reflection fluorescence (TIRF) microscope allows fluorophores to be imaged in a restricted region within an evanescent field of less than 200 nm from the interface of the coverslip and plasma membrane in living cells. Thus the TIRF microscope is useful for selectively visualizing the plasmalemmal surface and subplasmalemmal zone. In this review, we focused on a single-molecule analysis of the dynamic movement of ion channels in the plasma membrane using TIRF microscopy. We also described two single-molecule imaging techniques under TIRF microscopy: fluorescence resonance energy transfer (FRET) for the identification of molecules that interact with ion channels, and subunit counting for the determination of subunit stoichiometry in a functional channel. TIRF imaging can also be used to analyze spatiotemporal Ca(2+) events in the subplasmalemma. Single-molecule analyses of ion channels and localized Ca(2+) signals based on TIRF imaging provide beneficial pharmacological and physiological information concerning the functions of ion channels.

  15. Determination of copper nanoparticle size distributions with total reflection X-ray fluorescence spectroscopy

    SciTech Connect

    Singh, Andy; Luening, Katharina; Brennan, Sean; Homma, Takayuki; Kubo, Nobuhiro; Nowak, Stanisław H.; Pianetta, Piero

    2017-01-01

    Total reflection X-ray fluorescence (TXRF) analysis is extensively used by the semiconductor industry for measuring trace metal contamination on silicon surfaces. In addition to determining the quantity of impurities on a surface, TXRF can reveal information about the vertical distribution of contaminants by measuring the fluorescence signal as a function of the angle of incidence. In this study, two samples were intentionally contaminated with copper in non-deoxygenated and deoxygenated ultrapure water (UPW) resulting in impurity profiles that were either atomically dispersed in a thin film or particle-like, respectively. The concentration profile of the samples immersed into deoxygenated UPW was calculated using a theoretical concentration profile representative of particles, yielding a mean particle height of 16.1 nm. However, the resulting theoretical profile suggested that a distribution of particle heights exists on the surface. The fit of the angular distribution data was further refined by minimizing the residual error of a least-squares fit employing a model with a Gaussian distribution of particle heights about the mean height. The presence of a height distribution was also confirmed with atomic force microscopy measurements.

  16. Identification of novel insulin mimetic drugs by quantitative total internal reflection fluorescence (TIRF) microscopy

    PubMed Central

    Lanzerstorfer, Peter; Stadlbauer, Verena; Chtcheglova, Lilia A; Haselgrübler, Renate; Borgmann, Daniela; Wruss, Jürgen; Hinterdorfer, Peter; Schröder, Klaus; Winkler, Stephan M; Höglinger, Otmar; Weghuber, Julian

    2014-01-01

    Background and Purpose Insulin stimulates the transport of glucose in target tissues by triggering the translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Resistance to insulin, the major abnormality in type 2 diabetes, results in a decreased GLUT4 translocation efficiency. Thus, special attention is being paid to search for compounds that are able to enhance this translocation process in the absence of insulin. Experimental Approach Total internal reflection fluorescence (TIRF) microscopy was applied to quantify GLUT4 translocation in highly insulin-sensitive CHO-K1 cells expressing a GLUT4-myc-GFP fusion protein. Key Results Using our approach, we demonstrated GLUT4 translocation modulatory properties of selected substances and identified novel potential insulin mimetics. An increase in the TIRF signal was found to correlate with an elevated glucose uptake. Variations in the expression level of the human insulin receptor (hInsR) showed that the insulin mimetics identified stimulate GLUT4 translocation by a mechanism that is independent of the presence of the hInsR. Conclusions and Implications Taken together, the results indicate that TIRF microscopy is an excellent tool for the quantification of GLUT4 translocation and for identifying insulin mimetic drugs. PMID:25039620

  17. Determination of copper nanoparticle size distributions with total reflection X-ray fluorescence spectroscopy.

    PubMed

    Singh, Andy; Luening, Katharina; Brennan, Sean; Homma, Takayuki; Kubo, Nobuhiro; Nowak, Stanisław H; Pianetta, Piero

    2017-01-01

    Total reflection X-ray fluorescence (TXRF) analysis is extensively used by the semiconductor industry for measuring trace metal contamination on silicon surfaces. In addition to determining the quantity of impurities on a surface, TXRF can reveal information about the vertical distribution of contaminants by measuring the fluorescence signal as a function of the angle of incidence. In this study, two samples were intentionally contaminated with copper in non-deoxygenated and deoxygenated ultrapure water (UPW) resulting in impurity profiles that were either atomically dispersed in a thin film or particle-like, respectively. The concentration profile of the samples immersed into deoxygenated UPW was calculated using a theoretical concentration profile representative of particles, yielding a mean particle height of 16.1 nm. However, the resulting theoretical profile suggested that a distribution of particle heights exists on the surface. The fit of the angular distribution data was further refined by minimizing the residual error of a least-squares fit employing a model with a Gaussian distribution of particle heights about the mean height. The presence of a height distribution was also confirmed with atomic force microscopy measurements.

  18. Optical design and laser ablation of surface textures: demonstrating total internal reflection

    NASA Astrophysics Data System (ADS)

    Gommans, Hans; Booij, Silvia; Pijlman, Fetze; Krijn, Marcel; de Zwart, Siebe; Sepkhanov, Ruslan; Beaumont, Dave; van der Schaft, Hans; Sanders, Rene

    2015-09-01

    In lighting applications key drivers for optical design of surface textures are integration of optical elements, the disentanglement of optical functionality and appearance and late stage configuration. We investigated excimer laser ablation as a mastering technology for micro textured surfaces, where we targeted an increase in correspondence between surface design and ablated surface for high aspect ratio structures. To achieve this we have improved the photo mask design using a heuristic algorithm that corrects for the angular dependence of the ablation process and the loss of image resolution at ablation depths that exceed the depth of field. Using this approach we have been able to demonstrate close correspondence between designed and ablated facet structures up to 75° inclination at 75 μm depth. These facet design parameters allow for total internal reflection (TIR) as a means of beam deflection which is demonstrated in a range of mono shaped cone arrays in hexagonal tessellation. BSDF analysis was used to characterize the narrow TIR deflection beams that matched the peak positions of the design down to 28° apex. In addition, a single surface TIR-Fresnel lens design with focal distance 5 mm has been manufactured using this photo mask design algorithm and beam collimation up to 12° beam angle and 32° field angle is shown. These outcomes demonstrate that the laser ablation process intrinsically yields sufficient small dispersion in structure and fillet radii for lighting applications.

  19. Total reflection X-ray fluorescence analysis of pollen as an indicator for atmospheric pollution*1

    NASA Astrophysics Data System (ADS)

    Pepponi, G.; Lazzeri, P.; Coghe, N.; Bersani, M.; Gottardini, E.; Cristofolini, F.; Clauser, G.; Torboli, A.

    2004-08-01

    The viability of pollen is affected by environmental pollution and its use as a bio-indicator is proposed. Such effects can be observed and quantified by biological tests. However, a more accurate identification of the agents affecting the viability is required in order to validate the biological assay for environmental monitoring. The chemical analysis of pollen is meant to ascertain the existence of a correlation between its reduced biological functions and the presence of pollutants. Moreover, such biological systems act as accumulators and allow the detection and quantification of species present in the environment at low concentrations. Total reflection X-ray fluorescence analysis (TXRF) has been chosen for the investigation due to its high sensitivity, multielement capability and wide dynamic range. Corylus avellana L. (hazel) pollen has been collected in areas with different anthropic impact in the province of Trento, Italy. For the TXRF measurements, a liquid sample is needed, especially if a quantitative analysis is required. In the present work, the analysis after a microwave digestion has been compared with the analysis of a suspension of the pollen samples. In both cases, an internal standard has been used for the quantification. The concentrations of 17 elements ranging from Al to Pb have been determined in 13 samples. Analysis of the suspensions showed to be comparable to that of digested samples in terms of spectral quality, but the latter preparation method gave better reproducibility. Sub-ppm lowest limits of detection were obtained for iron and heavier elements detected.

  20. A laser induced fluorescence technique for quantifying transient liquid fuel films utilising total internal reflection

    NASA Astrophysics Data System (ADS)

    Alonso, Mario; Kay, Peter J.; Bowen, Phil J.; Gilchrist, Robert; Sapsford, Steve

    2010-01-01

    This paper describes the development of a laser induced fluorescence (LIF) technique to quantify the thickness and spatial distribution of transient liquid fuel films formed as a result of spray-wall interaction. The LIF technique relies on the principle that upon excitation by laser radiation the intensity of the fluorescent signal from a tracer like 3-pentanone is proportional to the film thickness. A binary solution of 10% (v/v) of 3-pentanone in iso-octane is used as a test fuel with a Nd:YAG laser as the excitation light source (utilising the fourth harmonic at wavelength 266 nm) and an intensified CCD camera is used to record the results as fluorescent images. The propagation of the excitation laser beam through the optical piston is carefully controlled by total internal reflection so that only the fuel film is excited and not the airborne droplets above the film, which had been previously shown to induce significant error. Other known sources of error are also carefully minimised. Calibrated temporally resolved benchmark results of a transient spray from a gasoline direct injector impinging on a flat quartz crown under atmospheric conditions are presented, with observations and discussion of the transient development of the fuel film. The calibrated measurements are consistent with previous studies of this event and demonstrate the applicability of the technique particularly for appraisal of CFD predictions. The potential utilisation of the technique under typical elevated ambient conditions is commented upon.

  1. 3D reconstruction of cortical microtubules using multi-angle total internal reflection fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Jin, Luhong; Xiu, Peng; Zhou, Xiaoxu; Fan, Jiannan; Kuang, Cuifang; Liu, Xu; Xu, Yingke

    2017-01-01

    Total internal reflection fluorescence microscopy (TIRFM) has been widely used in biomedical research to visualize cellular processes near the cell surface. In this study, a novel multi-angle ring-illuminated TIRFM system, equipped with two galvo mirrors that are on conjugate plan of a 4f optical system was developed. Multi-angle TIRFM generates images with different penetration depths through the controlled variation of the incident angle of illuminating laser. We presented a method to perform three-dimensional (3-D) reconstruction of microtubules from multi-angle TIRFM images. The performance of our method was validated in simulated microtubules with variable signal-to-noise ratios (SNR) and the axial resolution and accuracy of reconstruction were evaluated in selecting different numbers of illumination angles or in different SNR conditions. In U373 cells, we reconstructed the 3-D localization of microtubules near the cell surface with high resolution using over a hundred different illumination angles. Theoretically, the presented TIRFM setup and 3-D reconstruction method can achieve 40 nm axial resolution in experimental conditions where SNR is as low as 2, with 35 different illumination angles. Moreover, our system and reconstruction method have the potential to be used in live cells to track membrane dynamics in 3-D.

  2. Determination of copper nanoparticle size distributions with total reflection X-ray fluorescence spectroscopy

    DOE PAGES

    Singh, Andy; Luening, Katharina; Brennan, Sean; ...

    2017-01-01

    Total reflection X-ray fluorescence (TXRF) analysis is extensively used by the semiconductor industry for measuring trace metal contamination on silicon surfaces. In addition to determining the quantity of impurities on a surface, TXRF can reveal information about the vertical distribution of contaminants by measuring the fluorescence signal as a function of the angle of incidence. In this study, two samples were intentionally contaminated with copper in non-deoxygenated and deoxygenated ultrapure water (UPW) resulting in impurity profiles that were either atomically dispersed in a thin film or particle-like, respectively. The concentration profile of the samples immersed into deoxygenated UPW was calculatedmore » using a theoretical concentration profile representative of particles, yielding a mean particle height of 16.1 nm. However, the resulting theoretical profile suggested that a distribution of particle heights exists on the surface. The fit of the angular distribution data was further refined by minimizing the residual error of a least-squares fit employing a model with a Gaussian distribution of particle heights about the mean height. The presence of a height distribution was also confirmed with atomic force microscopy measurements.« less

  3. Visualizing substructure of Ca2+ waves by total internal reflection fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Bai, Yongqiang; Tang, Aihui; Wang, Shiqiang; Zhu, Xing

    2005-02-01

    Total internal reflection fluorescence microscope is a new optical microscopic system based on near-field optical theory. Its character of illumination by evanescent wave, together with the great signal-to-noise ratio and temporal resolution achieved by high quality CCD, allows us to analyze the spatiotemporal details of local Ca2+ dynamics within the nanoscale microdomain surrounding different Ca2+ channels. We have recently constructed a versatile objective TIRFM equipped with a high numerical aperture (NA=1.45) objective. Using fluo-4 as the Ca2+ indicator, we visualized the near-membrane profiles of Ca2+ waves and elementary Ca2+ sparks generated by Ca2+ release channels in rat ventricular myocytes. Different from those detected using conventional and confocal microscopy, Ca2+ waves observed with TIRFM exhibited fine inhomogenous substructures composed of fluctuating Ca2+ sparks. The anfractuous routes of spark recruitment suggested that the propagation of Ca2+ waves is much more complicated than previously imagined. We believe that TIRFM will provide a unique tool for dissecting the microscopic mechanisms of intracellular Ca2+ signaling.

  4. Total internal reflection holographic microscopy (TIRHM) for quantitative phase characterization of cell-substrate adhesion

    NASA Astrophysics Data System (ADS)

    Ash, William Mason, III

    Total Internal Reflection Holographic Microscopy (TIRHM) combines near-field microscopy with digital holography to produce a new form of near-field phase microscopy. Using a prism in TIR as a near-field imager, the presence of microscopic organisms, cell-substrate interfaces, and adhesions, causes relative refractive index (RRI) and frustrated TIR (f-TIR) to modulate the object beam's evanescent wave phase front. Quantitative phase images of test specimens such as Amoeba proteus, Dictyostelium Discoideum and cells such as SKOV-3 ovarian cancer and 3T3 fibroblasts are produced without the need to introduce stains or fluorophores. The angular spectrum method of digital holography to compensate for tilt anamorphism due to the inclined TIR plane is also discussed. The results of this work conclusively demonstrate, for the first time, the integration of near-field microscopy with digital holography. The cellular images presented show a correlation between the physical extent of the Amoeba proteus plasma membrane and the adhesions that are quantitatively profiled by phase cross-sectioning of the holographic images obtained by digital holography. With its ability to quantitatively characterise cellular adhesion and motility, it is anticipated that TIRHM can be a tool for characterizing and combating cancer metastasis, as well as improving our understanding of morphogenesis and embryogenesis itself.

  5. Total reflection X-ray fluorescence (TXRF) for direct analysis of aerosol particle samples.

    PubMed

    Bontempi, E; Zacco, A; Benedetti, D; Borgese, L; Colombi, P; Stosnach, H; Finzi, G; Apostoli, P; Buttini, P; Depero, L E

    2010-04-14

    Atmospheric aerosol particles have a great impact on the environment and on human health. Routine analysis of the particles usually involves only the mass determination. However, chemical composition and phases provide fundamental information about the particles' origins and can help to prevent health risks. For example, these particles may contain heavy metals such as Pb, Ni and Cd, which can adversely affect human health. In this work, filter samples were collected in Brescia, an industrial town located in Northern Italy. In order to identify the chemical composition and the phases of the atmospheric aerosols, the samples were analysed by means of total reflection X-ray fluorescence (TXRF) spectrometry with a laboratory instrument and X-ray microdiffraction at Synchrotron Daresbury Laboratories, Warrington (Cheshire, UK). The results are discussed and correlated to identify possible pollution sources. The novelty of this analytical approach is that filter samples for TXRF were analysed directly and did not require chemical pretreatment to leach elements from the aerosol particulates. The results of this study clearly show that TXRF is a powerful technique for the analysis of atmospheric aerosols on 'as-received' filters, thereby leaving samples intact and unaltered for possible subsequent analyses by other methods. In addition, the low detection limits for many elements (low ng/cm2) indicate that this method may hold promise in various application fields, such as nanotechnology.

  6. Design and Construction of a Multi-wavelength, Micromirror Total Internal Reflectance Fluorescence Microscope

    PubMed Central

    Larson, Joshua; Kirk, Matt; Drier, Eric A.; O’Brien, William; MacKay, James F.; Friedman, Larry; Hoskins, Aaron

    2015-01-01

    Colocalization Single Molecule Spectroscopy (CoSMoS) has proven to be a useful method for studying the composition, kinetics, and mechanisms of complex cellular machines. Key to the technique is the ability to simultaneously monitor multiple proteins and/or nucleic acids as they interact with one another. Here we describe a protocol for constructing a CoSMoS micromirror Total Internal Reflection Fluorescence Microscope (mmTIRFM). Design and construction of a scientific microscope often requires a number of custom components and a significant time commitment. In our protocol, we have streamlined this process by implementation of a commercially available microscopy platform designed to accommodate the optical components necessary for a mmTIRFM. The mmTIRF system eliminates the need for machining custom parts by the end-user and facilitates optical alignment. Depending on the experience-level of the microscope builder, these time-savings and the following protocol can enable mmTIRF construction to be completed within two months. PMID:25188633

  7. Measurement of Single Macromolecule Orientation by Total Internal Reflection Fluorescence Polarization Microscopy

    PubMed Central

    Forkey, Joseph N.; Quinlan, Margot E.; Goldman, Yale E.

    2005-01-01

    A new approach is presented for measuring the three-dimensional orientation of individual macromolecules using single molecule fluorescence polarization (SMFP) microscopy. The technique uses the unique polarizations of evanescent waves generated by total internal reflection to excite the dipole moment of individual fluorophores. To evaluate the new SMFP technique, single molecule orientation measurements from sparsely labeled F-actin are compared to ensemble-averaged orientation data from similarly prepared densely labeled F-actin. Standard deviations of the SMFP measurements taken at 40 ms time intervals indicate that the uncertainty for individual measurements of axial and azimuthal angles is ∼10° at 40 ms time resolution. Comparison with ensemble data shows there are no substantial systematic errors associated with the single molecule measurements. In addition to evaluating the technique, the data also provide a new measurement of the torsional rigidity of F-actin. These measurements support the smaller of two values of the torsional rigidity of F-actin previously reported. PMID:15894632

  8. Investigation of the effect of atmospheric dust on the determination of total ozone from the earth's ultraviolet reflectivity measurements, 2

    NASA Technical Reports Server (NTRS)

    Dave, J. V.

    1976-01-01

    Results of a detailed analysis of the simulated measurements for the BUV (Nimbus-4) configuration are described by using a total-ozone estimation procedure. A set of recommendations are discussed for increasing the accuracy and confidence level of the total ozone values estimated from the measurements of the earth's ultraviolet reflectivity at five different wavelengths (BUV configuration). A tentative procedure is also considered for the estimation of total ozone from measurements of reflectivity at six different wavelengths specified in the SBUV/TOMS (Nimbus-G) configuration.

  9. Efficacy of sevoflurane as an adjuvant to propofol-based total intravenous anesthesia for attenuating secretions in ocular surgery.

    PubMed

    Lai, Hou-Chuan; Chang, Yun-Hsiang; Huang, Ren-Chih; Hung, Nan-Kai; Lu, Chueng-He; Chen, Jou-Hsiu; Wu, Zhi-Fu

    2017-04-01

    The incidence of nasal secretions into the operative field is as high as 5% in ophthalmic surgery under general anesthesia. It may induce postoperative endophthalmitis. Secretions under propofol-based total intravanous anesthesia (TIVA) are greater than sevoflurane anesthesia during surgery. Postoperative nausea and vomiting (PONV) after inhalational anesthesia is higher than TIVA and may increase intraocluar pressure. We investigated the effect of sevoflurane combination with propofol-based TIVA on nasopharyngeal secretions and PONV in ocular surgery. Fifty patients undergoing ocular operations were randomly assigned for propofol-based TIVA or propofol/sevoflurane anesthesia. In the TIVA group (n = 25), anesthesia was induced and maintained with propofol and fentanyl; in the propofol/sevoflurane group (n = 25), 1% sevoflurane anesthesia was added. Nasopharyngeal excretion volume was significantly higher in the propofol-based TIVA group than in the propofol/sevoflurane group (31.0 ± 18.1 vs 13.7 ± 12.6 ml; P < .001). No significant difference in extubation time was noted (propofol-based TIVA: 6.4 ± 3.6 vs propofol/sevoflurane: 7.4 ± 3.0 minutes; P = .34). No postoperative endophthalmitis or PONV in both groups was observed. Sevoflurane attenuated secretions under propofol-based TIVA and did not increase the incidence of PONV or prolonged extubation in ocular surgery.

  10. Total Flavones of Choerospondias axillaris Attenuate Cardiac Dysfunction and Myocardial Interstitial Fibrosis by Modulating NF-κB Signaling Pathway.

    PubMed

    Sun, Bei; Xia, Qiumei; Gao, Zhiyong

    2015-07-01

    This study aimed to investigate the effect of total flavonoids of Choerospondias axillaris (TFC) on myocardial infarction (MI)-induced cardiac dysfunction, interstitial fibrosis and inflammatory reaction and further to clarify the potential signaling pathway involved. Rats were subjected to MI via coronary artery occlusion. The model establishment was confirmed by the occurrence of ST-segment elevation in electrocardiogram. Then, TFC was administrated at doses of 75, 150 and 300 mg/kg for 28 consecutive days (gavage). Body weight and heart weight were recorded. Hemodynamics, infarct size and myocardial fibrosis were examined. Blood samples were collected to determine tumor necrosis factor-α (TNF-α) and interleukin 6, 10 (IL-6, IL-10) levels. The expressions of matrix metalloproteinases-2, 9 (MMP-2, 9), phosphor-IKBα (p-IKBα) and transforming growth factor-β1 (TGF-β1) were assayed by Western blot. The results indicated that TFC significantly improved cardiac dysfunction, the heart coefficient and myocardial fibrosis in MI rat. TFC also decreased the levels of TNF-α and IL-6, but increased IL-10 content. Moreover, treatment with TFC protected the heart from chronic MI injury by decreasing the expressions of MMP-2, 9, TGF-β1 and p-IKBα. The results suggested that TFC attenuated cardiac dysfunction and myocardial interstitial fibrosis by modulating nuclear factor-kappa B (NF-κB) signaling pathway.

  11. Thermal dissociation cavity attenuated phase shift spectroscopy for continuous measurement of total peroxy and organic nitrates in the clean atmosphere

    NASA Astrophysics Data System (ADS)

    Sadanaga, Yasuhiro; Takaji, Ryo; Ishiyama, Ayana; Nakajima, Kazuo; Matsuki, Atsushi; Bandow, Hiroshi

    2016-07-01

    A thermal dissociation cavity attenuated phase shift spectroscopy (TD-CAPS) instrument was developed for measuring total peroxy nitrates (PNs) and organic nitrates (ONs) concentrations in the clean atmosphere. This instrument is easy to operate and can be applied to continuous measurement of PNs and ONs. A continuously measurable system is convenient to perform observations, especially in remote areas. Three lines (NO2, PNs, and ONs lines) were used for thermal dissociation. The NO2 line contains a quartz tube that is not heated, while the PN and ON lines contain quartz tubes that are heated at 433 K and 633 K, respectively. The concentrations of NO2, NO2 + PNs, and NO2 + PNs + ONs can be obtained from the NO2, PN, and ON lines, respectively. The lower limit values of the detection limit (3σ) for PNs and ONs were estimated to be 21 parts per trillion by volume with an integration time of 2 min. PNs were selectively thermally decomposed in the PNs line and formed NO2 quantitatively. In the ONs line, both PNs and ONs were thermally decomposed to produce NO2 quantitatively, but partial decomposition of HNO3 at 633 K interfered with the ONs measurement. Therefore, a HNO3 scrubber is required before the ONs line. Continuous observations were conducted with the TD-CAPS instrument in a remote area, and the instrument performed well for obtaining PNs and ONs concentrations.

  12. Using Total Internal Reflection Fluorescence Microscopy To Visualize Rhodopsin-Containing Cells

    PubMed Central

    Keffer, J. L.; Sabanayagam, C. R.; Lee, M. E.; DeLong, E. F.; Hahn, M. W.

    2015-01-01

    Sunlight is captured and converted to chemical energy in illuminated environments. Although (bacterio)chlorophyll-based photosystems have been characterized in detail, retinal-based photosystems, rhodopsins, have only recently been identified as important mediators of light energy capture and conversion. Recent estimates suggest that up to 70% of cells in some environments harbor rhodopsins. However, because rhodopsin autofluorescence is low—comparable to that of carotenoids and significantly less than that of (bacterio)chlorophylls—these estimates are based on metagenomic sequence data, not direct observation. We report here the use of ultrasensitive total internal reflection fluorescence (TIRF) microscopy to distinguish between unpigmented, carotenoid-producing, and rhodopsin-expressing bacteria. Escherichia coli cells were engineered to produce lycopene, β-carotene, or retinal. A gene encoding an uncharacterized rhodopsin, actinorhodopsin, was cloned into retinal-producing E. coli. The production of correctly folded and membrane-incorporated actinorhodopsin was confirmed via development of pink color in E. coli and SDS-PAGE. Cells expressing carotenoids or actinorhodopsin were imaged by TIRF microscopy. The 561-nm excitation laser specifically illuminated rhodopsin-containing cells, allowing them to be differentiated from unpigmented and carotenoid-containing cells. Furthermore, water samples collected from the Delaware River were shown by PCR to have rhodopsin-containing organisms and were examined by TIRF microscopy. Individual microorganisms that fluoresced under illumination from the 561-nm laser were identified. These results verify the sensitivity of the TIRF microscopy method for visualizing and distinguishing between different molecules with low autofluorescence, making it useful for analyzing natural samples. PMID:25769822

  13. In situ fluorescent protein imaging with metal film-enhanced total internal reflection microscopy.

    PubMed

    Burghardt, Thomas P; Charlesworth, Jon E; Halstead, Miriam F; Tarara, James E; Ajtai, Katalin

    2006-06-15

    Fluorescence detection of single molecules provides a means to investigate protein dynamics minus ambiguities introduced by ensemble averages of unsynchronized protein movement or of protein movement mimicking a local symmetry. For proteins in a biological assembly, taking advantage of the single molecule approach could require single protein isolation from within a high protein concentration milieu. Myosin cross-bridges in a muscle fiber are proteins attaining concentrations of approximately 120 muM, implying single myosin detection volume for this biological assembly is approximately 1 attoL (10(-18) L) provided that just 2% of the cross-bridges are fluorescently labeled. With total internal reflection microscopy (TIRM) an exponentially decaying electromagnetic field established on the surface of a glass-substrate/aqueous-sample interface defines a subdiffraction limit penetration depth into the sample that, when combined with confocal microscopy, permits image formation from approximately 3 attoL volumes. Demonstrated here is a variation of TIRM incorporating a nanometer scale metal film into the substrate/glass interface. Comparison of TIRM images from rhodamine-labeled cross-bridges in muscle fibers contacting simultaneously the bare glass and metal-coated interface show the metal film noticeably reduces both background fluorescence and the depth into the sample from which fluorescence is detected. High contrast metal film-enhanced TIRM images allow secondary label visualization in the muscle fibers, facilitating elucidation of Z-disk structure. Reduction of both background fluorescence and detection depth will enhance TIRM's usefulness for single molecule isolation within biological assemblies.

  14. Adhesion of living cells revealed by variable-angle total internal reflection fluorescence microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Cardoso Dos Santos, Marcelina; Vézy, Cyrille; Jaffiol, Rodolphe

    2016-02-01

    Total Internal Reflection Fluorescence Microscopy (TIRFM) is a widespread technique to study cellular process occurring near the contact region with the glass substrate. In this field, determination of the accurate distance from the surface to the plasma membrane constitutes a crucial issue to investigate the physical basis of cellular adhesion process. However, quantitative interpretation of TIRF pictures regarding the distance z between a labeled membrane and the substrate is not trivial. Indeed, the contrast of TIRF images depends on several parameters more and less well known (local concentration of dyes, absorption cross section, angular emission pattern…). The strategy to get around this problem is to exploit a series of TIRF pictures recorded at different incident angles in evanescent regime. This technique called variable-angle TIRF microscopy (vaTIRFM), allowing to map the membrane-substrate separation distance with a nanometric resolution (10-20 nm). vaTIRFM was developed by Burmeister, Truskey and Reichert in the early 1990s with a prism-based TIRF setup [Journal of Microscopy 173, 39-51 (1994)]. We propose a more convenient prismless setup, which uses only a rotatable mirror to adjust precisely the laser beam on the back focal plane of the oil immersion objective (no azimuthal scanning is needed). The series of TIRF images permit us to calculate accurately membrane-surface distances in each pixel. We demonstrate that vaTIRFM are useful to quantify the adhesion of living cells for specific and unspecific membrane-surface interactions, achieved on various functionalized substrates with polymers (BSA, poly-L-lysin) or extracellular matrix proteins (collagen and fibronectin).

  15. Sensitivity Studies for Space-based Measurement of Atmospheric Total Column Carbon Dioxide Using Reflected Sunlight

    NASA Technical Reports Server (NTRS)

    Mao, Jianping; Kawa, S. Randolph

    2003-01-01

    A series of sensitivity studies is carried out to explore the feasibility of space-based global carbon dioxide (CO2) measurements for global and regional carbon cycle studies. The detection method uses absorption of reflected sunlight in the CO2 vibration-rotation band at 1.58 microns. The sensitivities of the detected radiances are calculated using the line-by-line model (LBLRTM), implemented with the DISORT (Discrete Ordinates Radiative Transfer) model to include atmospheric scattering in this band. The results indicate that (a) the small (approx.1%) changes in CO2 near the Earth's surface are detectable in this CO2 band provided adequate sensor signal-to-noise ratio and spectral resolution are achievable; (b) the radiance signal or sensitivity to CO2 change near the surface is not significantly diminished even in the presence of aerosols and/or thin cirrus clouds in the atmosphere; (c) the modification of sunlight path length by scattering of aerosols and cirrus clouds could lead to large systematic errors in the retrieval; therefore, ancillary aerosol/cirrus cloud data are important to reduce retrieval errors; (d) CO2 retrieval requires good knowledge of the atmospheric temperature profile, e.g. approximately 1K RMS error in layer temperature; (e) the atmospheric path length, over which the CO2 absorption occurs, must be known in order to correctly interpret horizontal gradients of CO2 from the total column CO2 measurement; thus an additional sensor for surface pressure measurement needs to be attached for a complete measurement package.

  16. Using total internal reflection fluorescence microscopy to visualize rhodopsin-containing cells.

    PubMed

    Keffer, J L; Sabanayagam, C R; Lee, M E; DeLong, E F; Hahn, M W; Maresca, J A

    2015-05-15

    Sunlight is captured and converted to chemical energy in illuminated environments. Although (bacterio)chlorophyll-based photosystems have been characterized in detail, retinal-based photosystems, rhodopsins, have only recently been identified as important mediators of light energy capture and conversion. Recent estimates suggest that up to 70% of cells in some environments harbor rhodopsins. However, because rhodopsin autofluorescence is low-comparable to that of carotenoids and significantly less than that of (bacterio)chlorophylls-these estimates are based on metagenomic sequence data, not direct observation. We report here the use of ultrasensitive total internal reflection fluorescence (TIRF) microscopy to distinguish between unpigmented, carotenoid-producing, and rhodopsin-expressing bacteria. Escherichia coli cells were engineered to produce lycopene, β-carotene, or retinal. A gene encoding an uncharacterized rhodopsin, actinorhodopsin, was cloned into retinal-producing E. coli. The production of correctly folded and membrane-incorporated actinorhodopsin was confirmed via development of pink color in E. coli and SDS-PAGE. Cells expressing carotenoids or actinorhodopsin were imaged by TIRF microscopy. The 561-nm excitation laser specifically illuminated rhodopsin-containing cells, allowing them to be differentiated from unpigmented and carotenoid-containing cells. Furthermore, water samples collected from the Delaware River were shown by PCR to have rhodopsin-containing organisms and were examined by TIRF microscopy. Individual microorganisms that fluoresced under illumination from the 561-nm laser were identified. These results verify the sensitivity of the TIRF microscopy method for visualizing and distinguishing between different molecules with low autofluorescence, making it useful for analyzing natural samples. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  17. Deconstructing the Late Phase of Vimentin Assembly by Total Internal Reflection Fluorescence Microscopy (TIRFM)

    PubMed Central

    Winheim, Stefan; Hieb, Aaron R.; Silbermann, Marleen; Surmann, Eva-Maria; Wedig, Tatjana; Herrmann, Harald; Langowski, Jörg; Mücke, Norbert

    2011-01-01

    Quantitative imaging of intermediate filaments (IF) during the advanced phase of the assembly process is technically difficult, since the structures are several µm long and therefore they exceed the field of view of many electron (EM) or atomic force microscopy (AFM) techniques. Thereby quantitative studies become extremely laborious and time-consuming. To overcome these difficulties, we prepared fluorescently labeled vimentin for visualization by total internal reflection fluorescence microscopy (TIRFM). In order to investigate if the labeling influences the assembly properties of the protein, we first determined the association state of unlabeled vimentin mixed with increasing amounts of labeled vimentin under low ionic conditions by analytical ultracentrifugation. We found that bona fide tetrameric complexes were formed even when half of the vimentin was labeled. Moreover, we demonstrate by quantitative atomic force microscopy and electron microscopy that the morphology and the assembly properties of filaments were not affected when the fraction of labeled vimentin was below 10%. Using fast frame rates we observed the rapid deposition of fluorescently labeled IFs on glass supports by TIRFM in real time. By tracing their contours, we have calculated the persistence length of long immobilized vimentin IFs to 1 µm, a value that is identical to those determined for shorter unlabeled vimentin. These results indicate that the structural properties of the filaments were not affected significantly by the dye. Furthermore, in order to analyze the late elongation phase, we mixed long filaments containing either Alexa 488- or Alexa 647-labeled vimentin. The ‘patchy’ structure of the filaments obtained unambiguously showed the elongation of long IFs through direct end-to-end annealing of individual filaments. PMID:21544245

  18. Membrane order parameters for interdigitated lipid bilayers measured via polarized total-internal-reflection fluorescence microscopy.

    PubMed

    Ngo, An T; Jakubek, Zygmunt J; Lu, Zhengfang; Joós, Béla; Morris, Catherine E; Johnston, Linda J

    2014-11-01

    Incorporating ethanol in lipid membranes leads to changes in bilayer structure, including the formation of an interdigitated phase. We have used polarized total-internal-reflection fluorescence microscopy (pTIRFM) to measure the order parameter for Texas Red DHPE incorporated in the ethanol-induced interdigitated phase (LβI) formed from ternary lipid mixtures comprising dioleoylphosphatidylcholine, cholesterol and egg sphingomyelin or dipalmitoylphosphatidylcholine. These lipid mixtures have 3 co-existing phases in the presence of ethanol: liquid-ordered, liquid-disordered and LβI. pTIRFM using Texas Red DHPE shows a reversal in fluorescence contrast between the LβI phase and the surrounding disordered phase with changes in the polarization angle. The contrast reversal is due to changes in the orientation of the dye, and provides a rapid method to identify the LβI phase. The measured order parameters for the LβI phase are consistent with a highly ordered membrane environment, similar to a gel phase. An acyl-chain labeled BODIPY-FL-PC was also tested for pTIRFM studies of ethanol-treated bilayers; however, this probe is less useful since the order parameters of the interdigitated phase are consistent with orientations that are close to random, either due to local membrane disorder or to a mixture of extended and looping conformations in which the fluorophore is localized in the polar headgroup region of the bilayer. In summary, we demonstrate that order parameter measurements via pTIRFM using Texas Red-DHPE can rapidly identify the interdigitated phase in supported bilayers. We anticipate that this technique will aid further research in the effects of alcohols and other additives on membranes.

  19. Optical characterization of a radiochromic film by total reflectance and transmittance measurements.

    PubMed

    Fusi, Franco; Mercatelli, Luca; Marconi, Giacomo; Cuttone, Giacomo; Romano, Giovanni

    2004-07-01

    The GafChromic film (GCF) MD-55-2, a radiochromic material, was examined for its optical properties through total reflectance and transmittance measurements in visible spectrum (400-700 nm). By using a multilayer model of the film and Kubelka-Munk's (KM) theory, absorption and scattering coefficients of the film sensitive layer (K and S, respectively) were obtained from measurements of irradiated and nonirradiated slides. This has allowed calculation of the absorbance A(KM) of the sensitive layer of the GCF. The model easily splits scattering from absorption. Unlike absorption, scattering is essentially insensitive to irradiation dose and decreases slowly as the wavelength increases. The scattering effect is predominant over absorption in the 400-500 nm range, while beyond 600 nm absorption prevails. The A(KM) absorbance of the sensitive layer was calculated using the K coefficient and compared with the optical densities (OD) measured considering only ballistic photons (as in a standard spectrophotometer) as well as the optical densities measured collecting all the transmitted photons (as in many densitometers). The values of A(KM) found were always lower than OD measured by the other methods and they had the best linearity on the whole visible range. These data support the hypothesis that the sensitive layer reacts to irradiation more linearly than that shown by measurements using standard commercial devices. However, in the 600-680 nm range, correction is not very important because absorption is predominant over scattering. When GCF is used for imaging, scattering produces a loss of spatial information. Consequently, it is necessary to collect only ballistic photons and to correct absorbance by K and S coefficients.

  20. Actin dynamics at the living cell submembrane imaged by total internal reflection fluorescence photobleaching.

    PubMed Central

    Sund, S E; Axelrod, D

    2000-01-01

    Although reversible chemistry is crucial to dynamical processes in living cells, relatively little is known about relevant chemical kinetic rates in vivo. Total internal reflection/fluorescence recovery after photobleaching (TIR/FRAP), an established technique previously demonstrated to measure reversible biomolecular kinetic rates at surfaces in vitro, is extended here to measure reversible biomolecular kinetic rates of actin at the cytofacial (subplasma membrane) surface of living cells. For the first time, spatial imaging (with a charge-coupled device camera) is used in conjunction with TIR/FRAP. TIR/FRAP imaging produces both spatial maps of kinetic parameters (off-rates and mobile fractions) and estimates of kinetic correlation distances, cell-wide kinetic gradients, and dependences of kinetic parameters on initial fluorescence intensity. For microinjected rhodamine actin in living cultured smooth muscle (BC3H1) cells, the unbinding rate at or near the cytofacial surface of the plasma membrane (averaged over the entire cell) is measured at 0.032 +/- 0.007 s(-1). The corresponding rate for actin marked by microinjected rhodamine phalloidin is very similar, 0.033 +/- 0.013 s(-1), suggesting that TIR/FRAP is reporting the dynamics of entire filaments or protofilaments. For submembrane fluorescence-marked actin, the intensity, off-rate, and mobile fraction show a positive correlation over a characteristic distance of 1-3 microm and a negative correlation over larger distances greater than approximately 7-14 microm. Furthermore, the kinetic parameters display a statistically significant cell-wide gradient, with the cell having a "fast" and "slow" end with respect to actin kinetics. PMID:10969025

  1. Real-time monitoring of NKCC2 endocytosis by total internal reflection fluorescence (TIRF) microscopy.

    PubMed

    Jaykumar, Ankita Bachhawat; Caceres, Paulo S; Sablaban, Ibrahim; Tannous, Bakhos A; Ortiz, Pablo A

    2016-01-15

    The apical Na-K-2Cl cotransporter (NKCC2) mediates NaCl reabsorption by the thick ascending limb (TAL). The amount of NKCC2 at the apical membrane of TAL cells is determined by exocytic delivery, recycling, and endocytosis. Surface biotinylation allows measurement of NKCC2 endocytosis, but it has low time resolution and does not allow imaging of the dynamic process of endocytosis. We hypothesized that total internal reflection fluorescence (TIRF) microscopy imaging of labeled NKCC2 would allow monitoring of NKCC2 endocytosis in polarized Madin-Darby canine kidney (MDCK) and TAL cells. Thus we generated a NKCC2 construct containing a biotin acceptor domain (BAD) sequence between the transmembrane domains 5 and 6. Once expressed in polarized MDCK or TAL cells, surface NKCC2 was specifically biotinylated by exogenous biotin ligase (BirA). We also demonstrate that expression of a secretory form of BirA in TAL cells induces metabolic biotinylation of NKCC2. Labeling biotinylated surface NKCC2 with fluorescent streptavidin showed that most apical NKCC2 was located within small discrete domains or clusters referred to as "puncta" on the TIRF field. NKCC2 puncta were observed to disappear from the TIRF field, indicating an endocytic event which led to a decrease in the number of surface puncta at a rate of 1.18 ± 0.16%/min in MDCK cells, and a rate 1.09 ± 0.08%/min in TAL cells (n = 5). Treating cells with a cholesterol-chelating agent (methyl-β-cyclodextrin) completely blocked NKCC2 endocytosis. We conclude that TIRF microscopy of labeled NKCC2 allows the dynamic imaging of individual endocytic events at the apical membrane of TAL cells.

  2. Fluorescence intensity, lifetime, and anisotropy screening of living cells based on total internal reflection techniques

    NASA Astrophysics Data System (ADS)

    Bruns, Thomas; Angres, Brigitte; Steuer, Heiko; Strauss, Wolfgang S. L.; Schneckenburger, Herbert

    2009-02-01

    A setup for fluorescence measurements of surfaces of biological samples, in particular the plasma membrane of living cells, is described. The method is based on splitting of a laser beam and multiple total internal reflections (TIR) within the bottom of a microtiter plate, such that up to 96 individual samples are illuminated simultaneously by an evanescent electromagnetic field. Two different screening procedures for the detection of fluorescence arising from the plasma membrane of living cells by High Throughput Screening (HTS) and High Content Screening (HCS), are distinguished. In the first case a rapid measurement of large sample numbers based on fluorescence intensity, and in the second case a high content of information from a single sample based on the parameters fluorescence lifetime (Fluorescence Lifetime Screening, FLiS) and fluorescence anisotropy (Fluorescence Lifetime Polarization Screening, FLiPS) is achieved. Both screening systems were validated using cultivated cells incubated with different fluorescent markers (e. g. NBD-cholesterol) as well as stably transfected cells expressing a fluorescent membrane-associating protein. In addition, particularly with regard of potential pharmaceutical applications, the kinetics of the intracellular translocation of a fluorescent protein kinase c fusion protein upon stimulation of the cells was determined. Further, a caspase sensor based on Förster Resonance Energy Transfer (FRET) between fluorescent proteins was tested. Enhanced cyan fluorescent protein (ECFP) anchored to the inner leaflet of the plasma membrane of living cells transfers its excitation energy via a spacer (DEVD) to an enhanced yellow fluorescent protein (EYFP). Upon apoptosis DEVD is cleaved, and energy transfer is disrupted, as proven by changes in fluorescence intensity and decay times.

  3. Total reflection X-ray fluorescence spectrometers for multielement analysis: status of equipment

    NASA Astrophysics Data System (ADS)

    Ayala Jiménez, Rony E.

    2001-11-01

    Multielement analysis by total reflection X-ray fluorescence spectrometry has evolved during two decades. At present commercial equipment is available for chemical analysis of all types of biological and mineral samples. The electronic industry has also benefited from scientific and technological developments in this field due to new instrumentation to determine contamination on the surface of silicon wafers (the equipment will not be covered in this paper). The basic components of the spectrometers can be summarized as follows: (a) excitation source; (b) geometric arrangement (optics) for collimation and monochromatization of the primary radiation; (c) X-ray detector; and (d) software for operation of the instrument, data acquisition and spectral deconvolution to determine the concentrations of the elements (quantitative analysis). As an optional feature one manufacturer offers a conventional 45° geometry for direct excitation. Personal communications of the author and commercial brochures available have allowed us to list the components used in TXRF for multielement analysis. Excitation source: high-power sealed X-ray tubes, output from 1300 to 3000 W, different mixed alloy anodes Mo/W are used but molybdenum, tungsten and copper are common; single anode metal ceramic low power X-ray tubes, output up to 40 W. Excitation systems can be customized according to the requirements of the laboratory. Detector: silicon-lithium drifted semiconductor detector liquid nitrogen cooled; or silicon solid state thermoelectrically cooled detector (silicon drift detector SDD and silicon-PIN diode detector). Optics: multilayer monochromator of silicon-tungsten, nickel-carbon or double multilayer monochromator. Electronics: spectroscopy amplifier, analog to digital converter adapted to a PC compatible computer with software in a Windows environment for the whole operation of the spectrometer and for qualitative/quantitative analysis of samples are standard features in the

  4. Total reflection of x-ray fluorescence (TXRF): a mature technique for environmental chemical nanoscale metrology

    NASA Astrophysics Data System (ADS)

    Borgese, L.; Zacco, A.; Bontempi, E.; Colombi, P.; Bertuzzi, R.; Ferretti, E.; Tenini, S.; Depero, L. E.

    2009-08-01

    Total reflection x-ray fluorescence (TXRF) is a technique well established for chemical analysis of samples deposited as a thin layer. Nowadays it is mainly employed for electronic industry quality control. Recently, very compact and economic TXRF instrumentation was proposed. Combining this with the capability to analyze liquid samples, this technique is suitable to be employed in many different applications, comprising the very critical field of environmental analysis. Comparisons with the standard atomic absorption spectroscopy (AAS) technique show that TXRF is a practical, accurate, and reliable technique. Indeed, round-robin activities have already been started. Despite the efficiency and economy of the developed portable TXRF instrumentation, this is not widely employed for chemical laboratory analysis probably because TXRF is not an officially recognized technique, i.e. it is not yet normative-subjected. This fact could also be due to the long background of analytical applications developed for AAS, ICPS or inductively coupled plasma mass spectroscopy (ICP-MS) up to now. In this paper, we present a work of environmental monitoring of an industrial site, performed by means of bioindicators (lichens). The analysis of trace elements concentration in lichen was usually conducted with spectrophotometric techniques, such as AAS and ICP-MS, which were accepted by common regulations and normative-subjected. In this study, we accomplished a comparative lichen analysis by AAS and TXRF. The reproducibility of the obtained results showed the high correspondence between the two techniques. This comparison highlighted the versatility of the TXRF apparatus that allowed more rapid and simultaneous element detection. The obtained results suggested that this portable TXRF system could be suitable for regulation to produce certificated analysis upto ppb concentrations for some elements.

  5. Phase fluctuations of a radio wave in the case of total internal reflection from a randomly inhomogeneous ionosphere

    NASA Astrophysics Data System (ADS)

    Afanasiev, N. T.; Laryunin, O. A.; Markov, V. P.

    2009-10-01

    Based on the geometrical-optics approximation, we propose a method for calculation of statistical moments of the radio-wave phase in the case of total internal reflection from a randomly inhomogeneous ionosphere with a monotonic height profile of regular dielectric permittivity. To take into account the radio-wave scattering at the reflection point in a correct way, we perform analytical transformation of the eikonal equation solution derived in a first approximation of the perturbation method.

  6. Adjusting total body iron for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project.

    PubMed

    Mei, Zuguo; Namaste, Sorrel Ml; Serdula, Mary; Suchdev, Parminder S; Rohner, Fabian; Flores-Ayala, Rafael; Addo, O Yaw; Raiten, Daniel J

    2017-07-01

    Background: Total body iron (TBI) that is calculated from ferritin and soluble transferrin receptor (sTfR) allows for the evaluation of the full range of iron status from deficiency to excess. However, both ferritin and sTfR are affected by inflammation and malaria, which may require a statistical adjustment. TBI has been used to assess iron status in the United States, but its use worldwide and in settings with inflammation has been limited.Objective: We examine whether inflammation-adjusted ferritin and sTfR concentrations affect TBI values and the prevalence of low TBI (<0 mg/kg) in preschool children (PSC) (age range: 6-59 mo) and women of reproductive age (WRA) (age range: 15-49 y).Design: Cross-sectional data for PSC (8 surveys; n = 8413) and WRA (4 surveys; n = 4258) from the Biomarkers Reflecting the Inflammation and Nutritional Determinants of Anemia (BRINDA) project were analyzed individually and combined. TBI and the prevalence of low TBI were compared following 3 adjustment approaches for ferritin and sTfR: 1) the exclusion of individuals with inflammation (C-reactive protein concentration >5 mg/L or α-1-acid glycoprotein concentration >1 g/L), 2) the application of arithmetic correction factors, and 3) the use of regression correction.Results: Regardless of the method that was used to adjust ferritin and sTfR for inflammation, the adjusted mean TBI decreased in both PSC and WRA compared with unadjusted values. Subsequently, inflammation-adjusted TBI increased the prevalence of low TBI by a median of 4-14 percentage points (pps) in PSC and 1-3 pps in WRA compared with unadjusted TBI. The regression approach resulted in a greater median increase than was achieved with the exclusion or correction-factor approaches, and accounting for malaria in addition to inflammation did not have an added effect on the prevalence estimates.Conclusion: The prevalence of low TBI is underestimated if it is not adjusted by inflammation, particularly in children living in

  7. Synchrotron Radiation Total Reflection X-ray Fluorescence Spectroscopy for Microcontamination Analysis on Silicon Wafer Surfaces

    SciTech Connect

    Takaura, Norikatsu

    1997-10-01

    As dimensions in state-of-the-art CMOS devices shrink to less than 0.1 pm, even low levels of impurities on wafer surfaces can cause device degradation. Conventionally, metal contamination on wafer surfaces is measured using Total Reflection X-Ray Fluorescence Spectroscopy (TXRF). However, commercially available TXRF systems do not have the necessary sensitivity for measuring the lower levels of contamination required to develop new CMOS technologies. In an attempt to improve the sensitivity of TXRF, this research investigates Synchrotron Radiation TXRF (SR TXRF). The advantages of SR TXRF over conventional TXRF are higher incident photon flux, energy tunability, and linear polarization. We made use of these advantages to develop an optimized SR TXRF system at the Stanford Synchrotron Radiation Laboratory (SSRL). The results of measurements show that the Minimum Detection Limits (MDLs) of SR TXRF for 3-d transition metals are typically at a level-of 3x10{sup 8} atoms/cm{sup 2}, which is better than conventional TXRF by about a factor of 20. However, to use our SR TXRF system for practical applications, it was necessary to modify a commercially available Si (Li) detector which generates parasitic fluorescence signals. With the modified detector, we could achieve true MDLs of 3x10{sup 8} atoms/cm{sup 2} for 3-d transition metals. In addition, the analysis of Al on Si wafers is described. Al analysis is difficult because strong Si signals overlap the Al signals. In this work, the Si signals are greatly reduced by tuning the incident beam energy below the Si K edge. The results of our measurements show that the sensitivity for Al is limited by x-ray Raman scattering. Furthermore, we show the results of theoretical modeling of SR TXRF backgrounds consisting of the bremsstrahlung generated by photoelectrons, Compton scattering, and Raman scattering. To model these backgrounds, we extended conventional theoretical models by taking into account several aspects particular

  8. Adjusting total body iron for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

    PubMed Central

    Namaste, Sorrel ML; Serdula, Mary; Suchdev, Parminder S; Rohner, Fabian; Flores-Ayala, Rafael; Addo, O Yaw; Raiten, Daniel J

    2017-01-01

    Background: Total body iron (TBI) that is calculated from ferritin and soluble transferrin receptor (sTfR) allows for the evaluation of the full range of iron status from deficiency to excess. However, both ferritin and sTfR are affected by inflammation and malaria, which may require a statistical adjustment. TBI has been used to assess iron status in the United States, but its use worldwide and in settings with inflammation has been limited. Objective: We examine whether inflammation-adjusted ferritin and sTfR concentrations affect TBI values and the prevalence of low TBI (<0 mg/kg) in preschool children (PSC) (age range: 6–59 mo) and women of reproductive age (WRA) (age range: 15–49 y). Design: Cross-sectional data for PSC (8 surveys; n = 8413) and WRA (4 surveys; n = 4258) from the Biomarkers Reflecting the Inflammation and Nutritional Determinants of Anemia (BRINDA) project were analyzed individually and combined. TBI and the prevalence of low TBI were compared following 3 adjustment approaches for ferritin and sTfR: 1) the exclusion of individuals with inflammation (C-reactive protein concentration >5 mg/L or α-1-acid glycoprotein concentration >1 g/L), 2) the application of arithmetic correction factors, and 3) the use of regression correction. Results: Regardless of the method that was used to adjust ferritin and sTfR for inflammation, the adjusted mean TBI decreased in both PSC and WRA compared with unadjusted values. Subsequently, inflammation-adjusted TBI increased the prevalence of low TBI by a median of 4–14 percentage points (pps) in PSC and 1–3 pps in WRA compared with unadjusted TBI. The regression approach resulted in a greater median increase than was achieved with the exclusion or correction-factor approache