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Sample records for total reflection atr

  1. 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. PMID:26195028

  2. 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. PMID:26449810

  3. 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-specific calibration.

  4. 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-THz spectroscopy combined with appropriate chemometric can be a potential for a rapid determination of sugar concentrations.

  5. 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.

  6. Attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy of oxidized polymer-modified bitumens.

    PubMed

    Yut, Iliya; Zofka, Adam

    2011-07-01

    Oxidative age hardening of bitumen results in increasing fatigue susceptibility of bituminous mixtures, thus reducing the service life of asphalt pavements. Polymer additives to bitumen have been shown to improve its viscoelastic properties and, in some cases, reduce the level of bitumen hardening. Fourier transform infrared (FT-IR) spectroscopy enables evaluation of oxidation levels in bitumen by measuring the concentration of oxygen-containing chemical functionalities. This paper summarizes the results of the investigation of oxidative age hardening of polymer-modified bitumens (PMB) caused by accelerated aging in laboratory conditions. The PMB samples are prepared with different concentrations of styrene-butadiene-based co-polymers. Next, the PMB samples are aged using standard procedures that employ air blowing at 163 C for 85 min followed by conditioning the samples at 100 C and 2.1 MPa pressure for 20 to 48 hours. The resultant changes in their chemical composition are evaluated by portable attenuated total reflection (ATR) spectrometer. Measurements of ketone, sulfoxide, and hydroxyl content in PMB samples indicated similar oxidation pathways to those of non-modified bitumens. In addition, no evidence of polymer degradation due to accelerated aging of PMB was found in this study. PMID:21740638

  7. 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 Central

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

    2012-01-01

    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. PMID:24300186

  8. 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

    2012-01-01

    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. PMID:24300186

  9. Simultaneous monitoring of curing shrinkage and degree of cure of thermosets by attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy.

    PubMed

    Fernndez-Francos, Xavier; Kazarian, Sergei G; Ramis, Xavier; Serra, ngels

    2013-12-01

    We present a novel methodology to simultaneously monitor of the degree of cure and curing shrinkage of thermosetting formulations. This methodology is based on the observation of changes in the infrared absorption of reactive functional groups and the groups used as a standard reference for normalization. While the optical path length is exact and controlled in transmission infrared spectroscopy, in attenuated total reflection Fourier transform infrared (ATR FT-IR), the exact determination of volume changes requires the measurement of the refractive indices of the studied system throughout the curing process or at least an indirect parallel measurement of this property. The methodology presented here allows one to achieve quantitative measurements of the degree of cure and shrinkage for thermosets using in situ ATR FT-IR spectroscopy. PMID:24359657

  10. 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.

  11. Fluorescence, CD, attenuated total reflectance (ATR) FTIR, and sup 13 C NMR characterization of the structure and dynamics of synthetic melittin and melittin analogues in lipid environments

    SciTech Connect

    Weaver, A.J.; Prendergast, F.G. ); Kemple, M.D. ); Brauner, J.W.; Mendelsohn, R. )

    1992-02-11

    The structure and dynamics of synthetic melittin (MLT) and MLT analogues bound to monomyristoylphosphatidylcholine micelles, dimyristoylphosphatidylcholine vesicles, and diacylphosphatidylcholine films have been investigated by fluorescence, CD, attenuated total reflectance (ATR) FTIR, and {sup 13}C NMR spectroscopy. All of these methods provide information about peptide secondary structure and/or about the environment of the single tryptophan side chain in these lipid environments. ATR-FTIR data provide additional information about the orientation of helical peptide segments with respect to the bilayer plane. Steady-state fluorescence anisotropy, fluorescence lifetime, and {sup 13}C NMR relaxation data are used in concert to provide quantitative information about the dynamics of a single {sup 13}C{alpha}-labeled glycine incorporated into each of the MLT peptides at position 12. The cumulative structural and dynamic data are consistent with a model wherein the N-terminal {alpha}-helical segment of these peptides is oriented perpendicular to the bilayer plane. Correlation times for the lysolipid-peptide complexes provide evidence for binding of a single peptide monomer per micelle. A model for the membranolytic action of MLT and MLT-like peptides is proposed.

  12. 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, ?-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. PMID:25172681

  13. An attenuated total reflection (ATR) and Raman spectroscopic investigation into the effects of chloroquine on Plasmodium falciparum-infected red blood cells.

    PubMed

    Kozicki, M; Creek, D J; Sexton, A; Morahan, B J; Wesełucha-Birczyńska, A; Wood, B R

    2015-04-01

    Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and Raman spectroscopy were used to compare chloroquine (CQ)-treated and untreated cultured Plasmodium falciparum-infected human red blood cells (iRBCs). The studies were carried out in parallel from the same starting cultures using both spectroscopic techniques, in duplicate. ATR FTIR spectra showed modifications in the heme vibrational bands as well as increases in the CH2/CH3 stretching bands in the 3100-2800 cm(-1) region of CQ-treated iRBCs consistent with an increase in lipid content. Other changes consisted of secondary structural variations including shifts in the amide I and II modes, along with changes in RNA and carbohydrate bands. Raman microspectroscopy of single red blood cells using 532 nm revealed subtle changes in the positions and intensity of ν37 of the core size region marker band and ν4 in the pyrrole ring-stretching region between untreated and CQ-treated iRBCs. Similar patterns in the corresponding relations were also observed in the non-fundamental (overtone region) between the control and treated cells. These differences were consistent with higher levels of oxygenated hemoglobin (oxyHb) in the treated cells as shown in a Principle Component Analysis (PCA) loadings plot. The results obtained demonstrate that vibrational spectroscopic techniques can provide insight into the effect of quinolines on iRBCs and thus may assist understanding the sensitivity and resistance of new and existing anti-malarial drugs. PMID:25654140

  14. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy as a bedside diagnostic tool for detecting renal disease biomarkers in fresh urine samples

    NASA Astrophysics Data System (ADS)

    Oliver, Katherine V.; Matjiu, Faith; Davey, Cameron; Moochhala, Shabbir; Unwin, Robert J.; Rich, Peter R.

    2015-03-01

    Attenuated total reflection (ATR)-FTIR spectroscopy is a convenient technique for analysing biomedical samples because of its sensitivity to subtle compositional changes, speed of data acquisition and ease of sample preparation. We have applied the technology to the detection of disease biomarkers in urine and investigated the translation of these diagnostic methods to simple bench-top spectrometers. To demonstrate the use of ATR-FTIR spectroscopy as a bedside diagnostic tool, we have installed a roomtemperature bench-top infrared spectrometer in the renal unit at the Royal Free Hospital (RFH), London. A nurse recorded spectra of urine from patients with a range of conditions, including diabetes, kidney disease, stone disease and urinary tract infections, and the data were correlated to medical conditions to assess the diagnostic capabilities of the system and to identify potential spectral patterns associated with disease. Two hundred and six spectra have been recorded to date; these show it is possible to detect urea, creatinine, protein, lipids, sugars and other minor metabolites, including potential disease biomarkers. Several spectral peaks of potential diagnostic interest were identified that show variations between normal and disease samples.

  15. 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. PMID:26647047

  16. 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

  17. Attenuated total reflectance-mid infrared spectroscopy (ATR-MIR) coupled with independent components analysis (ICA): A fast method to determine plasticizers in polylactide (PLA).

    PubMed

    Kassouf, Amine; Ruellan, Alexandre; Jouan-Rimbaud Bouveresse, Delphine; Rutledge, Douglas N; Domenek, Sandra; Maalouly, Jacqueline; Chebib, Hanna; Ducruet, Violette

    2016-01-15

    Compliance of plastic food contact materials (FCMs) with regulatory specifications in force, requires a better knowledge of their interaction phenomena with food or food simulants in contact. However these migration tests could be very complex, expensive and time-consuming. Therefore, alternative procedures were introduced based on the determination of potential migrants in the initial material, allowing the use of mathematical modeling, worst case scenarios and other alternative approaches, for simple and fast compliance testing. In this work, polylactide (PLA), plasticized with four different plasticizers, was considered as a model plastic formulation. An innovative analytical approach was developed, based on the extraction of qualitative and quantitative information from attenuated total reflectance (ATR) mid-infrared (MIR) spectral fingerprints, using independent components analysis (ICA). Two novel chemometric methods, Random_ICA and ICA_corr_y, were used to determine the optimal number of independent components (ICs). Both qualitative and quantitative information, related to the identity and the quantity of plasticizers in PLA, were retrieved through a direct and fast analytical method, without any prior sample preparations. Through a single qualitative model with 11 ICs, a clear and clean classification of PLA samples was obtained, according to the identity of plasticizers incorporated in their formulations. Moreover, a quantitative model was established for each formulation, correlating proportions estimated by ICA and known concentrations of plasticizers in PLA. High coefficients of determination (higher than 0.96) and recoveries (higher than 95%) proved the good predictability of the proposed models. PMID:26592648

  18. Comparison between ATR-IR, Raman, concatenated ATR-IR and Raman spectroscopy for the determination of total antioxidant capacity and total phenolic content of Chinese rice wine.

    PubMed

    Wu, Zhengzong; Xu, Enbo; Long, Jie; Pan, Xiaowei; Xu, Xueming; Jin, Zhengyu; Jiao, Aiquan

    2016-03-01

    The application of attenuated total reflectance infrared spectroscopy (ATR-IR), Raman spectroscopy (RS) and combination of ATR-IR and RS for measurements of total antioxidant capacity (TAC) and total phenolic content (TPC) of Chinese rice wine (CRW) were investigated in this study. Synergy interval partial least-squares (SiPLS), support vector machine (SVM) and principal component analysis (PCA) were applied to process the merged data from two individual instruments. It was observed that the performances of models based on the RS spectra were better than those based on the ATR-IR spectra. In addition, SVM models based on the efficient information extracted from ATR-IR and RS spectra were superior to PLS models based on the same information and PLS models based on ATR-IR or RS spectra. The overall results demonstrated that integrating ATR-IR and RS was possible and could improve the prediction accuracy of TAC and TPC in CRWs. PMID:26471606

  19. Optimized data analysis algorithm for on-site chemical identification using a hand-held attenuated total reflection Fourier transform infrared (ATR FT-IR) spectrometer.

    PubMed

    Ron, Izhar; Zaltsman, Amalia; Kendler, Shai

    2013-12-01

    On-site identification of organic compounds in the presence of interfering materials using a field-portable attenuated total reflection Fourier transform infrared (ATR FT-IR) spectrometer is presented. Identification is based on an algorithm that compares the analyte's infrared absorption spectrum with the reference spectra. The comparison is performed at several predetermined frequencies, and a similarity value (distance) between the measured and the reference spectra is calculated either at each frequency individually, or, alternatively, the average distance for all frequencies is calculated. The examined frequencies are selected to give the best contrast between the target materials of interest. In this study, the algorithm was optimized to identify three common chemical warfare agents (CWAs): O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioic acid (VX), sarin (GB), and sulfur mustard (bis(2-chloroethyl) sulfide) (HD), in the presence of field-related interfering materials (fuels, water, and dust). Receiver operating characteristics analysis was performed in order to determine the probabilities for detection (PD) and for false alerts (PF). Challenging the algorithm with a set of data that contains mixtures of CWAs and interfering materials resulted in PD of 90% and PF of 0%, 0%, and 1% for VX, GB, and HD, respectively, using the average distance approach, which was found to be much more effective than analyzing each frequency individually. This finding was validated for all possible combinations of 2-7 peaks per material. It is suggested that this algorithm provides a reliable mean for the identification of a predetermined set of target analytes and interfering materials. PMID:24359653

  20. Identification of natural dyes on laboratory-dyed wool and ancient wool, silk, and cotton fibers using attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy and Fourier transform Raman spectroscopy.

    PubMed

    Bruni, Silvia; De Luca, Eleonora; Guglielmi, Vittoria; Pozzi, Federica

    2011-09-01

    Attenuated total reflection (ATR) infrared and Fourier transform (FT) Raman spectra were obtained from wool threads dyed in the laboratory with natural dyes used in antiquity, following a procedure similar to ancient methods for dyeing wool. The ATR spectra were primarily dominated by the signals of the wool, making it difficult to identify the dye on the fibers only by visual inspection of the infrared spectrum. However, the Raman spectra showed more significant characteristics attributable to the dyes as previously studied in the literature on modern synthetic dyes. A library-search method was thus applied to the second derivatives of both the ATR and Raman spectra to verify the possibility of identifying the dye. Two libraries were constructed, one consisting of the ATR spectra of undyed wool (raw, washed, and mordanted) and the transmission spectra of pure dyes and the other consisting of the Raman spectra of undyed wool and of pure dyes. Correlation and first-derivative correlation search algorithms were used. The results presented here suggest that the two types of spectroscopy are complementary in this kind of work, allowing the almost complete identification of historic dyes on wool. In fact, through the combined use of the two searches, most dyes were identified with a good index of similarity and within the first five hits. Only for annatto was identification totally impossible using either technique. Subsequently the same method was applied to wool, silk, and cotton threads taken from ancient Caucasian and Chinese textiles. PMID:21929856

  1. 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. PMID:26725502

  2. 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

    Gmez-De-Anda, Fabin; Dorantes-lvarez, Lidia; Gallardo-Velzquez, Tzayhri; Osorio-Revilla, Guillermo; Caldern-Domnguez, Georgina; Martnez 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. PMID:22364689

  3. 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. PMID:26767638

  4. 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. PMID:26162559

  5. 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. PMID:26647055

  6. Effects of pH and metal ions on the conformation of bovine serum albumin in aqueous solution An attenuated total reflection (ATR) FTIR spectroscopic study

    NASA Astrophysics Data System (ADS)

    Qing, Huai; Yanlin, He; Fenlin, Sheng; Zuyi, Tao

    1996-11-01

    The Hummel-Dreyer gel permeation technique has been applied to investigate the binding of bovine serum albumin (BSA) with Zn 2+ and Cd 2+, and has provided evidence for the existence of two different types of binding sites in the BSA molecule. The effects of pH and the presence of metal ions Zn 2- and Cd 2+ on the conformation of BSA were investigated using ATR FTIR Spectroscopy. The results demonstrated that there were different conformational states in BSA at pH 5.0 and 9.0. Furthermore, we observed the spectral changes of BSA in the amide I region and major metal ion (Zn 2+ and Cd 2+) binding sites which were C?O and C?N groups of BSA.

  7. 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.

  8. 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 4cm(-1). The measurements for sodium glutamate were performed at 1347cm(-)(1) (baseline correction between 1322 and 1369cm(-1)). In the case of sorbitol, the measurements were done at 890cm(-1) (baseline correction between 825 and 910cm(-1)) using a nominal resolution of 2cm(-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. PMID:26992492

  9. Attenuated total reflectance spectroscopy with chirped-pulse upconversion.

    PubMed

    Shirai, Hideto; Duchesne, Constance; Furutani, Yuji; Fuji, Takao

    2014-12-01

    Chirped-pulse upconversion technique has been applied to attenuated total reflectance (ATR) infrared spectroscopy. An extremely broadband infrared pulse was sent to an ATR diamond prism and the reflected pulse was converted to the visible by using four-wave mixing in krypton gas. Absorption spectra of liquids in the range from 200 to 5500 cm(-1) were measured with a visible spectrometer on a single-shot basis. The system was applied to observe the dynamics of exchanging process of two solvents, water and acetone, which give clear vibrational spectral contrast. We observed that the exchange was finished within ∼ 10 ms. PMID:25606893

  10. 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. PMID:26767642

  11. 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. PMID:22462902

  12. Infrared attenuated total reflection spectroscopy for the characterization of gold nanoparticles in solution.

    PubMed

    Lpez-Lorente, ngela Inmaculada; Sieger, Markus; Valcrcel, Miguel; Mizaikoff, Boris

    2014-01-01

    In situ synthesis of bare gold nanoparticles mediated by stainless steel as reducing agent was monitored via infrared attenuated total reflection (IR-ATR) spectroscopy. Gold nanoparticles were directly synthesized within the liquid cell of the ATR unit taking immediate advantage of the stainless steel walls of the ATR cell. As nanoparticles were formed, a layer of particles was deposited at the SiO2 ATR waveguide surface. Incidentally, the absorption bands of water increased resulting from surface-enhanced infrared absorption (SEIRA) effects arising from the presence of the gold nanoparticles within the evanescent field. Next to the influence of the Au(III) precursor concentration and the temperature, the suitability of IR-ATR spectroscopy as an innovative tool for investigating changes of nanoparticles in solution, including their aggregation promoted by an increase of the ionic strength or via a pH decrease, and for detailing the sedimentation process of gold nanoparticles was confirmed. PMID:24313342

  13. Surface-enhanced, multi-dimensional attenuated total reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Kraack, Jan Philip; Lotti, Davide; Hamm, Peter

    2015-08-01

    Ultrafast two-dimensional infrared spectroscopy (2D IR) spectroscopy is performed in attenuated total reflectance (ATR) geometry with the Kretschmann configuration in order to measure femtosecond to picosecond dynamics of self-assembled monolayers on gold-coated solid-liquid interfaces. In the monolayers low-absorbing (<200 M-1 cm-1) nitrile functional groups are used as local vibrational probes to monitor vibrational relaxation and spectral diffusion in dependence of different environments of the nitrile group. By comparing spectral diffusion dynamics of the vibrational probe in bulk solution and in the monolayer we find that the dynamics are slowed down by more than a factor of 20 upon immobilization of the sample. Moreover, spectral diffusion dynamics are affected by the local environment within the monolayers as evidenced by 2D ATR IR experiments on mixed monolayers with different aliphatic and aromatic co-adsorbates. The results are interpreted in terms of absent excitation energy-transfer as well as solvation dynamics around the nitrile vibrational probe. Our results demonstrate that 2D ATR IR spectroscopy offers the possibility to obtain ultrafast dynamics from sub-monolayer coverages of even low-absorbing vibrational probes such as nitrile functional groups.

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

    PubMed

    Boulet-Audet, Maxime; Buffeteau, Thierry; Boudreault, Simon; Daugey, Nicolas; Pzolet, 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 distorted ATR spectra. PMID:20507143

  15. Total sulfur determination in residues of crude oil distillation using FT-IR/ATR and variable selection methods

    NASA Astrophysics Data System (ADS)

    Mller, Aline Lima Hermes; Picoloto, Rochele Sogari; Mello, Paola de Azevedo; Ferro, Marco Flores; dos Santos, Maria de Ftima Pereira; Guimares, Regina Clia Loureno; Mller, Edson Irineu; Flores, Erico Marlon Moraes

    2012-04-01

    Total sulfur concentration was determined in atmospheric residue (AR) and vacuum residue (VR) samples obtained from petroleum distillation process by Fourier transform infrared spectroscopy with attenuated total reflectance (FT-IR/ATR) in association with chemometric methods. Calibration and prediction set consisted of 40 and 20 samples, respectively. Calibration models were developed using two variable selection models: interval partial least squares (iPLS) and synergy interval partial least squares (siPLS). Different treatments and pre-processing steps were also evaluated for the development of models. The pre-treatment based on multiplicative scatter correction (MSC) and the mean centered data were selected for models construction. The use of siPLS as variable selection method provided a model with root mean square error of prediction (RMSEP) values significantly better than those obtained by PLS model using all variables. The best model was obtained using siPLS algorithm with spectra divided in 20 intervals and combinations of 3 intervals (911-824, 823-736 and 737-650 cm-1). This model produced a RMSECV of 400 mg kg-1 S and RMSEP of 420 mg kg-1 S, showing a correlation coefficient of 0.990.

  16. Total sulfur determination in residues of crude oil distillation using FT-IR/ATR and variable selection methods.

    PubMed

    Mller, Aline Lima Hermes; Picoloto, Rochele Sogari; de Azevedo Mello, Paola; Ferro, Marco Flores; de Ftima Pereira dos Santos, Maria; Guimares, Regina Clia Loureno; Mller, Edson Irineu; Flores, Erico Marlon Moraes

    2012-04-01

    Total sulfur concentration was determined in atmospheric residue (AR) and vacuum residue (VR) samples obtained from petroleum distillation process by Fourier transform infrared spectroscopy with attenuated total reflectance (FT-IR/ATR) in association with chemometric methods. Calibration and prediction set consisted of 40 and 20 samples, respectively. Calibration models were developed using two variable selection models: interval partial least squares (iPLS) and synergy interval partial least squares (siPLS). Different treatments and pre-processing steps were also evaluated for the development of models. The pre-treatment based on multiplicative scatter correction (MSC) and the mean centered data were selected for models construction. The use of siPLS as variable selection method provided a model with root mean square error of prediction (RMSEP) values significantly better than those obtained by PLS model using all variables. The best model was obtained using siPLS algorithm with spectra divided in 20 intervals and combinations of 3 intervals (911-824, 823-736 and 737-650 cm(-1)). This model produced a RMSECV of 400 mg kg(-1) S and RMSEP of 420 mg kg(-1) S, showing a correlation coefficient of 0.990. PMID:22257712

  17. 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).

  18. Attenuated Total Reflection FTIR spectroscopy of Ultrathin Dielectrics Films

    NASA Astrophysics Data System (ADS)

    Liu, Ran

    2003-03-01

    Characterization of ultrathin dielectric films and surface layers becomes extremely crucial in the semiconductor industry. Although the standard transmission and reflection Fourier Transformed Infrared (FTIR) spectroscopy provides rich structural and chemical information, the lack of sensitivity in comparison with other surface techniques such as X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) calls for application of new IR sampling technique for ultrathin layer analysis. This paper will demonstrate the powerfulness of Attenuated Total Reflection (ATR) as a unique FTIR probing method that is capable of analyzing dielectric films with thickness down to 1 nm. Examples will be given in areas of characterization of regular (SiO_2, SiON), low-k (SiOF), and high-k (HfO_2, HfSiO_x, SrTiO_3) films on Si.

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

    PubMed

    Schumacher, Henrik; Knzelmann, 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. PMID:20828439

  20. Use of attenuated total reflectance Fourier transform infrared spectroscopy to identify microbial metabolic products on carbonate mineral surfaces.

    PubMed

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

    2008-07-01

    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

  1. 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. PMID:26699522

  2. Excitation of optical modes supported by strong absorption in organic thin films at attenuated total reflection geometry

    NASA Astrophysics Data System (ADS)

    Aoki, K.; Wakamatsu, T.

    2014-12-01

    Reflection dips observed at attenuated total reflection (ATR) geometry for metal thin films are interpreted from excitations of surface plasmon polaritons. We have presented that the absorption induced by enhanced electric fields in a metal film is an origin of this phenomenon (Wakamatsu et al (2007 J. Opt. Soc. Am. B 24 2307)). This viewpoint provides that ATR dips can be generated not only in metals but in other materials. Here, the absorption spectra of copper phthalocyanine (CuPc) thin films were observed at ATR geometry without a metal layer. Only from p-polarized ATR measurements was a strong absorption dip observed in the short wavelength region of the CuPc absorption bands. Kramers-Kronig analyses for the transmittance spectra of a CuPc thin film revealed that the refractive index of the film lowers around the spectral position of the p-polarized ATR dip. Transfer matrix analyses indicated that the lowered refractive index of CuPc induces the enhancement of evanescent fields in the film. These results demonstrate that the ATR dip generation is attributable to the absorption derived from enhanced evanescent fields in the CuPc film.

  3. [Quantitative analysis of surface composition of polypropylene blends using attenuated total reflectance FTIR spectroscopy].

    PubMed

    Chen, Han-jia; Zhu, Ya-fei; Zhang, Yi; Xu, Jia-rui

    2008-08-01

    The surface composition and structure of solid organic polymers influence many of their properties and applications. Oligomers such as poly(ethylene glycol) (PEG), poly(methyl methacrylate) (PMMA) poly(butyl methacrylate) (PBMA) and their graft copolymers of polybutadiene and polypropylene were used as the macromolecular surface modifiers of polypropylene. The compositions on surface and in bulk of the polypropylene (PP) blends were determined quantitatively using attenuated total reflectance FTIR spectroscopic (ATR-FTIR) technique with a variable-angle multiple-reflection ATR accessory and FTIR measurements, respectively. By validating by Lambert-Beer law, 1103 and 1733 cm(-1) can be used to represent modifiers characteristic absorbance band to determine quantitatively the surface composition of modifiers including poly(ethylene glycol) and carbonyl segment in PP blends, respectively. The determination error can be effectively eliminated by calibrating wavelength and using absorption peak area ratio as the calibrating basis for the quantitative analysis. To minimize the effect of contact between the polymer film and the internal reflection element on the results of absolute absorbance, the technique of "band ratioing" was developed, and it was testified that the error of the peak area ratios of interest can be reduced to 5% or below, which was suitable for ATR-FTIR used as a determining quantitative tool for surface composition. The working curves were then established and used to calculate the composition of the responding functional groups in the film surface of the PP blends. The depth distribution of modifiers on the surface of blend films also can be determined by changing the incident angle of interest on the basis of the equation of the depth of penetration of the excursion wave in ATR spectra. The results indicated that ATR-FTIR can be used to determine quantitatively the surface composition and distribution of modifiers with reproducible and reliable measurement results. PMID:18975806

  4. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  6. 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 ?m. Therefore, all GSR particles sized 4.7 ?m or larger will be resolved and detected on the tape substrate using micro-ATR imaging. PMID:24588255

  7. A study of magneto-optical effect in dilute Fe3O4 ferro-fluid by attenuated total reflection, ferro-magnetic resonance and Faraday rotation

    NASA Astrophysics Data System (ADS)

    Poh Pang, Chin; Hsieh, Chang-Tsun; Lue, Juh-Tzeng

    2003-03-01

    Physical parameters such as dielectric constant and susceptibility of dilute Fe3O4 ferrofluids derived directly from attenuated total reflection (ATR) and ferromagnetic resonance (FMR), respectively, were exploited to delineate the corresponding Faraday rotation angles with respect to applied magnetic fields. Theoretical estimation was compared with experimental measurements adducing that the effective medium theory is admittedly correct and ATR becomes a fertilized method to study the magneto-optical effects of ferrofluids.

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

    PubMed Central

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

    2014-01-01

    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. PMID:25358261

  9. Study of total internal reflection switch

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Qi, Wei; Li, Yubo; Hao, Yinlei; Jiang, Xiaoqing; Wang, Minghua; Yang, Jianyi

    2008-12-01

    The optical waveguide switch utilizing the principle of total internal reflection (TIR) is a promising structure since its merits such as compact size, digital response characteristic, insensitivity to wavelength and polarization, and so on. In this paper the TIR switch is studied both in theory and in experiment. At first, we give a comprehensive analysis about reflection mechanism in the TIR switch from the following three issues: the grazing incidence of a narrow beam in the free space, the beam reflection in a bounded space, and the beam expansion induced by the reflection in a two-dimensional gradient field of the refractive index decrease. Then based on the analytical works, we successfully fabricate practical TIR switches by utilizing the thermo-optical effect of polymer and the carrier injection effect of GaAs (both the current injection and the photon injection manners are employed). The testing results show that: the extinction ratio of the thermo-optical TIR switch exceeds 35 dB at an power consumption of 80 mW; for the carrier injection TIR switch utilizing the current injection manner, its operation speed is faster than 20 ns and its operation current is about 70 mA.

  10. Potential Modulation on Total Internal Reflection Ellipsometry.

    PubMed

    Liu, Wei; Niu, Yu; Viana, A S; Correia, Jorge P; Jin, Gang

    2016-03-15

    Electrochemical-total internal reflection ellipsometry (EC-TIRE) has been proposed as a technique to observe the redox reactions on the electrode surface due to its high phase sensitivity to the electrolyte/electrode interface. In this paper, we mainly focus on the influence of the potential modulation on the TIRE response. The analysis suggests that both dielectric constant variation of gold and the electric double layer transformation would modulate the reflection polarization of the surface. For a nonfaradaic process, the signal of TIRE would be proportional to the potential modulation. To testify the analysis, linear sweep voltammetry and open circuit measurement have been performed. The results strongly support the system analysis. PMID:26889871

  11. Total-reflection x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Jibaoui, H.; Erre, D.; Cazaux, J.

    2001-07-01

    This contribution describes a new microscopy based on the total reflection of grazing-incident x rays. The corresponding instrument permits, for the first time, acquiring x-ray total-reflection images of surfaces and interfaces. It is a laboratory instrument based on the modification of a scanning electron microscope equipped with a special mechanical setup and a charge-coupled-device camera but without any focusing element for the x rays. The principle of such microscopy is given with a description of the corresponding instrument. The various parameters characterizing its performance are given and are illustrated by some selected images of surfaces acquired in a few seconds and related to surface areas (of the imaged region) of about 1 mm2. It is, in particular, a lateral resolution restricted to the micrometer range but associated with a relief resolution in the nanometer range and to a rapid detection of isolated details on very flat surfaces. Special attention is devoted to interface imaging.

  12. 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.

  13. 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

  14. 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.}

  15. Synchrotron radiation total reflection for rainwater analysis

    NASA Astrophysics Data System (ADS)

    Simabuco, Silvana Moreira; Matsumoto, Edson

    2001-07-01

    In this work Total Reflection X-Ray Fluorescence Analysis with excitation by Synchrotron Radiation (SR-TXRF) has been used for rainwater trace element analysis. The samples were collected in four different sites at Campinas City, SP, Brazil. Rainwater samples of 10 ?l were added to Perspex reflector disks, dried under vacuum and analyzed for 100 s measuring time. For the calibration system standard solutions with gallium as internal standard were prepared. The detection limits obtained for K-shell lines varied from 29 ng.ml-1 for sulfur to 1.3 ng.ml-1 for zinc and copper, while for L-shell the values were 4.5 ng.ml-1 for mercury and 7.0 ng.ml-1 for lead.

  16. Total internal reflection photoacoustic detection spectroscopy

    NASA Astrophysics Data System (ADS)

    Sudduth, Amanda S. M.; Goldschmidt, Benjamin S.; Samson, Edward B.; Whiteside, Paul J. D.; Viator, John A.

    2011-03-01

    Total Internal Reflection Photoacoustic Spectroscopy (TIRPAS) is a method that exploits the evanescent field of a nanosecond duration laser pulse reflecting off a glass/water interface to generate photoacoustic responses. These photoacoustic events are generated in light absorbing analytes suspended in the fluid medium in contact with the glass that are within the penetration depth of the evanescent wave. This method has been employed in previous studies by Hinoue et al. Hinoue et al. used an optically chopped HeNe laser at 632.8 nm to detect Brilliant Blue FCF dye at different angles of incidence. In recent years, the advent of high power nanosecond pulsed tunable lasers has allowed for the re-visitation of the TIRPAS idea under stress confinement and orders of magnitude larger peak energy conditions. Compared to conventional detection methods, this approach has the potential to detect much smaller quantities of disease indicators, such as circulating tumor cells and hemazoin crystals in malaria, than other optical methods. The detection limit of the TIRPAS system was quantified using chlorazol black solution with an absorption coefficient of 55 cm-1 at 532 nm. Interaction with the evanescent field was verified by varying the angle of incidence of the probe laser beam that generated the photoacoustic waves, thereby changing the penetration depth of the evanescent field as well as the photoacoustic spectroscopy effect from angled excitation.

  17. 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 ?m) 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 ?m). An 11-28 W, 10.2 or 10.6 ?m 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).

  18. Far- and Deep-UV Spectroscopy of Semiconductor Nanoparticles Measured Based on Attenuated Total Reflectance spectroscopy.

    PubMed

    Tanabe, Ichiro; Yamada, Yosuke; Ozaki, Yukihiro

    2016-02-01

    Far- and deep-ultraviolet spectra (150-300?nm) of semiconductor nanoparticles (zinc oxide and zinc sulfide) are successfully measured by using attenuated total reflectance (ATR) spectroscopy, and analyzed using finite-difference time-domain (FDTD) simulations. The obtained spectra show good consistency with earlier synchrotron-radiation spectra and with theoretical calculations. The FDTD simulation results show that the present system collected the correct spectra. In the present system, the obtained spectra are affected by the real part n of the complex refractive index more strongly than the imaginary part k. It is also revealed both experimentally and theoretically that spectral intensities of the semiconductor nanoparticles are approximately one tenth those of liquid samples. These results provide insights into the far- and deep-ultraviolet spectroscopy based on the ATR system, and show the general applicability of our original ATR spectroscopy to semiconductor nanoparticles. The system needs neither high vacuum nor much space, and enables rapid and systematic investigation of the electronic states of various materials. PMID:26691240

  19. On the production of glycogen by Pseudomonas fluorescens during biofilm development: an in situ study by attenuated total reflection-infrared with chemometrics.

    PubMed

    Quils, Fabienne; Humbert, Franois

    2014-01-01

    Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to monitor Pseudomonas fluorescens biofilms in situ, non-destructively, in real time, and under fully hydrated conditions. Changes accompanying the metabolic evolution of the sessile bacterial cells from the nascent biofilm monolayer to the beginning of the multi-layered structure in the presence of nutrients were identified via the ATR-FTIR fingerprints of the young biofilm on the ATR crystal. The ATR-FTIR spectra were analysed by classical methods (time evolution of integrated intensities and profile evolution of specific bands), and also by a multivariate curve resolution, Bayesian positive source separation, to extract the pure component spectra and their change of concentration over time occurring during biofilm settlement. This work showed clearly the overproduction of glycogen by sessile P. fluorescens, which had not previously been described by other research groups. PMID:24835847

  20. Contact pressure effects on vibrational bands of kaolinite during infrared spectroscopic measurements in a diamond attenuated total reflection cell.

    PubMed

    Friedrich, Frank; Weidler, Peter G

    2010-05-01

    Over the last decades infrared spectroscopy has become a frequently used method to investigate the structure and bonding properties of clay minerals. Along with classic transmission techniques, attenuated total reflection (ATR) spectroscopy has been applied as a very fast and easy method. In this study we compared transmission spectra of kaolinite with ATR spectra obtained by a single-reflection diamond ATR accessory (Golden Gate Mark II). The ATR spectra showed anomalous band positions that were obviously affected by the applied contact pressure of the sapphire anvil. Most of these vibrations can be assigned to basal Si-O bonds and all of them shifted their positions to lower wavenumbers. It is suggested that these peak shifts are due to changes in the Si-O-Si bond angle Theta. They are caused by distortions and rotations of SiO(4) units within the tetrahedral sheet, due to shear forces perpendicular to the uniaxial pressure applied by the anvil. Furthermore, the intensity of a normally very weak transversal optical mode (TO mode) of the inner surface hydroxyls (3684 cm(-1)) remarkably increased with increasing contact pressure, while the longitudinal optical mode (LO mode) at 3694 cm(-1) strongly decreased its intensity. This possibly is determined by a strong alignment of the platy kaolinite particles along their ab-planes due to the applied pressure. PMID:20482968

  1. ATR-FTIR Spectroscopy in the Undergraduate Chemistry Laboratory: Part I--Fundamentals and Examples

    ERIC Educational Resources Information Center

    Schuttlefield, Jennifer D.; Grassian, Vicki H.

    2008-01-01

    Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is a useful technique for measuring the infrared spectra of solids and liquids as well as probing adsorption on particle surfaces. Several examples of the use of FTIR-ATR spectroscopy in different undergraduate chemistry laboratory courses are presented here. These…

  2. ATR-FTIR Spectroscopy in the Undergraduate Chemistry Laboratory: Part I--Fundamentals and Examples

    ERIC Educational Resources Information Center

    Schuttlefield, Jennifer D.; Grassian, Vicki H.

    2008-01-01

    Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is a useful technique for measuring the infrared spectra of solids and liquids as well as probing adsorption on particle surfaces. Several examples of the use of FTIR-ATR spectroscopy in different undergraduate chemistry laboratory courses are presented here. These

  3. Frustrated Total Internal Reflection: A Simple Application and Demonstration.

    ERIC Educational Resources Information Center

    Zanella, F. P.; Magalhaes, D. V.; Oliveira, M. M.; Bianchi, R. F.; Misoguti, L.; Mendonca, C. R.

    2003-01-01

    Describes the total internal reflection process that occurs when the internal angle of incidence is equal to or greater than the critical angle. Presents a demonstration of the effect of frustrated total internal reflection (FTIR). (YDS)

  4. Surface-Active Lipid Linings under Shear Load--A Combined in-Situ Neutron Reflectivity and ATR-FTIR Study.

    PubMed

    Schwörer, Felicitas; Trapp, Marcus; Ballauff, Matthias; Dahint, Reiner; Steitz, Roland

    2015-10-27

    We study shear effects in solid-supported lipid membrane stacks by simultaneous combined in-situ neutron reflectivity (NR) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The stacks mimic the terminal surface-active phospholipid (SAPL) coatings on cartilage in mammalian joints. Piles of 11 bilayer membranes of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) are immobilized at the interface of the solid silicon support and the liquid D2O backing phase. We replace the natural hyaluronic acid (HA) component of synovial fluid by a synthetic substitute, namely, poly(allylamine hydrochloride) (PAH), at identical concentration. We find the oligolamellar DMPC bilayer films strongly interacting with PAH resulting in a drastic increase of the membranes d spacing (by a factor of ∼5). Onset of shear causes a buckling-like deformation of the DMPC bilayers perpendicular to the applied shear field. With increasing shear rate we observe substantially enhanced water fractions in the membrane slabs which we attribute to increasing fragmentation caused by Kelvin-Helmholtz-like instabilities parallel to the applied shear field. Both effects are in line with recent theoretical predictions on shear-induced instabilities of lipid bilayer membranes in water (Hanasaki, I.; Walther, J. H.; Kawano, S.; Koumoutsakos, P. Phys. Rev. E 2010, 82, 051602). With the applied shear the interfacial lipid linings transform from their gel state Pβ' to their fluid state Lα. Although in chain-molten state with reduced bending rigidity the lipid layers do not detach from their solid support. We hold steric bridging of the fragmented lipid bilayer membranes by PAH molecules responsible for the unexpected mechanical stability of the DMPC linings. PMID:26388226

  5. Application of attenuated total reflectance Fourier transform infrared spectroscopy in the mineralogical study of a landslide area, Hungary

    NASA Astrophysics Data System (ADS)

    Udvardi, Beatrix; Kovcs, Istvn Jnos; Knya, Pter; Fldvri, Mria; Fri, Judit; Budai, Ferenc; Falus, Gyrgy; Fancsik, Tams; Szab, Csaba; Szalai, Zoltn; Mihly, Judith

    2014-11-01

    This study demonstrates that the unpolarized attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) is a practical and quick tool to distinguish different types of sediments in landslide-affected areas, and potentially other types of physical environments too. Identification and quantification of minerals by ATR FTIR is implemented on a set of powdered natural sediments from a loess landslide (Kulcs, Hungary). A protocol including sample preparation, analytical conditions and evaluation of sediment ATR spectra is outlined in order to identify and estimate major minerals in sediments. The comparison of the defined FTIR parameters against qualitative and quantitative results of X-ray diffraction and thermal analysis was used to validate the use of ATR FTIR spectroscopy for the considered sediments. The infrared band areas and their ratios (water/carbonates; silicates/carbonates; kaolinite) appear to be the most sensitive parameters to identify strongly weathered sediments such as paleosols and red clays which most likely facilitate sliding and could form sliding zones. The effect of grain size and orientation of anisotropic minerals on the wave number and intensity of some major absorption bands is also discussed.

  6. Adhesive secretions of live mussels observed in situ by attenuated total reflection-infrared spectroscopy.

    PubMed

    Gao, Zhihong; Bremer, Phil J; Barker, Michael F; Tan, Eng Wui; McQuillan, A James

    2007-01-01

    The chemical species involved in the adhesion of blue mussels (Mytilus galloprovincialis) and greenshell mussels (Perna canaliculus) to surfaces has been investigated using in situ attenuated total reflection infrared (ATR-IR) spectroscopy. Mussel spat ranging in size from 0.5 to 25 mm were placed in a flow cell containing a ZnSe multiple internal reflection prism and supplied with temperature-controlled seawater. Distinctively different absorption spectra were obtained when the mussels were predominantly moving across the surface or forming permanent bonds. With limited movement, the absorption spectrum was characteristic of protein with peaks near 1647 cm-1 (amide I), 1543 cm-1 (amide II), and 1235 cm-1 (amide III). When the mussels were observed to be moving across the surface of the ATR-IR crystal there was a strong broad absorption maximum around 1200-900 cm-1 (carbohydrate polymers), presumably due to the secretion of a weakly acidic mucopolysaccharide. Distinct differences in the spectra obtained from the adhesive secretions of blue or greenshell mussels were not observed. The data presented is the first reported use of IR spectroscopy to obtain in situ, real-time, chemical data on the interactions between invertebrates and substrates immersed in sea water. PMID:17311717

  7. Detection of Citrus Huanglongbing by Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR) Spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  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. 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.

  10. ATR-FTIR Spectroscopy in the Undergraduate Chemistry Laboratory: Part II--A Physical Chemistry Laboratory Experiment on Surface Adsorption

    ERIC Educational Resources Information Center

    Schuttlefield, Jennifer D.; Larsen, Sarah C.; Grassian, Vicki H.

    2008-01-01

    Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is a useful technique for measuring the infrared spectra of solids and liquids as well as probing adsorption on particle surfaces. The use of FTIR-ATR spectroscopy in organic and inorganic chemistry laboratory courses as well as in undergraduate research was presented…

  11. ATR-FTIR Spectroscopy in the Undergraduate Chemistry Laboratory: Part II--A Physical Chemistry Laboratory Experiment on Surface Adsorption

    ERIC Educational Resources Information Center

    Schuttlefield, Jennifer D.; Larsen, Sarah C.; Grassian, Vicki H.

    2008-01-01

    Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is a useful technique for measuring the infrared spectra of solids and liquids as well as probing adsorption on particle surfaces. The use of FTIR-ATR spectroscopy in organic and inorganic chemistry laboratory courses as well as in undergraduate research was presented

  12. Attenuated total reflectance Fourier-transform infrared spectroscopic investigation of silicon heterojunction solar cells.

    PubMed

    Holovský, Jakub; De Wolf, Stefaan; Jiříček, Petr; Ballif, Christophe

    2015-07-01

    Silicon heterojunction solar cells critically depend on the detailed properties of their amorphous/crystalline silicon interfaces. We report here on the use of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy to gain precise insight into the vibrational properties of the surfaces and ultrathin layers present in such solar cells. We fabricate ATR prisms from standard silicon wafers similar to those used for device fabrication. In this fashion, we acquire very-high sensitivity FTIR information on device-relevant structures. Our method has no requirement for minimum layer thickness, enabling the study of the impact of the different fabrication process steps on the film microstructure. We discuss the necessary requirements for the method implementation and give a comprehensive overview of all observed vibration modes. In particular, we study vibrational signatures of Si-H(X), Si-H(X)(Si(Y)O(Z)), B-H, hydroxyl groups, and hydrocarbons on the Si(111) surface. We observe subtle effects in the evolution of the chemical state of the surface during sample storage and process-related wafer handling and discuss their effect on the electronic properties of the involved interfaces. PMID:26233357

  13. Evaluation of drug crystallinity in aqueous suspension using terahertz time-domain attenuated total reflection spectroscopy.

    PubMed

    Takebe, Gen; Kawada, Yoichi; Akiyama, Koichiro; Takahashi, Hironori; Takamoto, Hisayoshi; Hiramatsu, Mitsuo

    2013-11-01

    Terahertz pulsed spectroscopy has recently been demonstrated to be a novel technique for the investigation of the solid-state properties of pharmaceutical materials. In this study, we directly measured the crystallinity of a drug suspended in water, using a terahertz pulsed attenuated total reflection (ATR) method. The dihydropyridine calcium channel blocker nifedipine is classified as a poorly soluble drug; its most stable crystalline form is known as form I. Transmission spectra, collected from 0.2 to 2.0 THz (6.6 to 66 cm(-1) ), of nifedipine crystals had a strong absorption peak at 1.2 THz (40 cm(-1) ) at room temperature. When the nifedipine crystals were mixed with poloxamer 188 and suspended in water, the resulting spectra measured using the ATR method had a peak at the same frequency as in the spectra obtained in transmission mode. Furthermore, the peak area was proportional to the amount of crystals. The upward sloping baseline in the spectra, corresponding to water absorption, decreased stepwise with increasing amounts of crystalline particles. We confirmed that the spectra gave excellent quantitative results, using partial least-squares regression analysis. The results suggest the possibility of using this method for qualitative and quantitative assessments of crystalline drugs in suspension. PMID:24037861

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

    PubMed

    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 ?-?? 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. PMID:22852667

  15. Detection of Ni2+ by a dimethylglyoxime probe using attenuated total-reflection infrared spectroscopy.

    PubMed

    Ponnuswamy, Thomas; Chyan, Oliver

    2002-04-01

    A new analytical approach for the detection of Ni2+ utilizing an attenuated total reflection (ATR) technique is discussed in this paper. Nickel detection was accomplished on a silicon ATR parallelogram crystal uniformly coated by a ca. 1.5-microm Nafion film embedded with dimethylglyoxime (DMG) probe molecules. The detection of Ni2+ is based on the appearance of a unique infrared absorption peak at 1572 cm(-1) that corresponds to the C=N stretching mode in the nickel dimethylglyoximate, Ni(DMG)2, complex. The suitable operational pH range for the nickel infrared sensor is between 6 - 8. High alkalinity in the sample solution causes a leaching of Ni(DMG)2. The detection limit of the nickel infrared sensor is 1 ppm in a sample solution of pH = 8. Interference studies revealed that Cu2+ could compete with Ni2+ for the DMG sites in the Nafion matrix. The new nickel detection methodology can be potentially utilized, after further improvement, in field analysis to locate hot spots contaminated with a high ppm of Ni2+. PMID:11999521

  16. [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. PMID:26601359

  17. High-sensitivity infrared attenuated total reflectance sensors for in situ multicomponent detection of volatile organic compounds in water.

    PubMed

    Lu, Rui; Li, Wen-Wei; Mizaikoff, Boris; Katzir, Abraham; Raichlin, Yosef; Sheng, Guo-Ping; Yu, Han-Qing

    2016-02-01

    In situ detection of volatile organic compounds (VOCs) in aqueous environments is imperative for ensuring the quality and safety of water supplies, yet it remains a challenging analytical task. We present a high-sensitivity method for in situ analysis of multicomponent VOCs at low concentrations based on the use of infrared attenuated total reflection (IR-ATR) spectroscopy. This protocol uses a unique ATR waveguide, which comprises a planar silver halide (AgClxBr1-x) fiber with cylindrical extensions at both ends to increase the number of internal reflections, and a polymer coating that traps VOCs and excludes water molecules. Depending on the type of VOC and measurement scenario, IR spectra with specific frequency windows, scan times and spectral resolutions are obtained, from which concentration information is derived. This protocol allows simultaneous detection of multiple VOCs at concentrations around 10 p.p.b., and it enables accurate quantification via a single measurement within 5 min without the need for sample collection or sample pretreatment. This IR-ATR sensor technology will be useful for other applications; we have included a procedure for the analysis of protein conformation changes in Supplementary Methods as an example. PMID:26820794

  18. 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.; Kpper, L.; Pittermann, W.; Stcker, 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.

  19. 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.

  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.

    PubMed

    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. PMID:24387384

  2. Determination of the polymorphic forms of bicifadine hydrochloride by differential scanning calorimetry-thermogravimetric analysis, X-ray powder diffraction, attenuated total reflectance-infrared spectroscopy, and attenuated total reflectance-near-infrared spectroscopy.

    PubMed

    McArdle, Patrick; Gilligan, Karen; Cunningham, Desmond; Ryder, Alan

    2005-11-01

    The pharmaceutical compound bicifadine hydrochloride, which has been found to crystallize in two polymorphic forms, has been characterized by thermal analysis, X-ray powder diffraction (XRPD), infrared (IR) spectroscopy, and near-infrared (NIR) spectroscopy. A series of 22 sample mixtures of polymorph 1 and polymorph 2 were prepared and calibration models for the quantitation of these binary mixtures have been developed for each of the XRPD, attenuated total reflectance (ATR)-IR, and ATR-NIR analytical techniques. The quantitative results were obtained using a partial least squares (PLS) algorithm, which predicted the concentration of polymorph 1 from the XRPD spectra with a root mean standard error of prediction (RMSEP) of 4.4%, from the IR spectra with a RMSEP of 3.8%, and from the NIR spectra with a RMSEP of 1.4%. The studies indicate that when analyses are carried out on equivalent sets of spectra, NIR spectroscopy offers significant advantages in quantitative accuracy as a tool for the determination of polymorphs in the solid state and is also more convenient to use than both the ATR-IR and XRPD methods. Density functional theory (DFT) B3LYP calculations and IR spectral simulation have been used to determine the nature of the vibrational modes that are the most sensitive in the analysis. PMID:16316514

  3. 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 and more variable thickness than for the spin-coated samples. The IR spectra revealed an increase in vicinal silanol generation over the first 3 days of conditioning followed by geminal silanol generation. Thus, the structural change detected by NR and XR roughly coincided with the onset of geminal silanol generation. Finally, little change in the reflectivity data was observed for films conditioned with D{sub 2}O at 80 C for 1 month. This indicates that hydrolysis of Si-O-Si is much slower with D{sub 2}O than with H{sub 2}O.

  4. 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. PMID:17042173

  5. Attenuated total reflectance-fourier transform infrared microspectroscopy of copper(II) complexes with reduced dextran derivatives

    NASA Astrophysics Data System (ADS)

    Nikoli?, G. S.; Caki?, M.; Miti?, .; Ili?, B.; Premovi?, P.

    2009-09-01

    Dextran is a water-soluble, extracellular neutral polysaccharide with a linear flexible chain of ?-(1 ? 6)-linked ?-D-glucopyranose units, in a single compounds. In alkali solutions Cu(II) ion forms complexes with reduced low-molar dextran (RLMD). The metal content and the solution composition depended on pH. The complexing process begins in weak alkali solution (pH > 7), and involves OH groups in C2 and C3 dextran monomer units. Synthesized copper(II) complexes with RLMD, of average molar mass M w = 5000 g/mol were investigated by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and FTIR imaging microscopy. ATR-FTIR microspectroscopic data of synthesized complexes are rare in literature. The changes in intensity and width of the IR bands in region 1500-1000 cm-1 were related to changes in conformation and short-range interactions of the ligand dextran. FTIR microscopy images shows more and less ordered structures of the Cu(II)-RLMD complexes. ATR-FTIR microspectroscopic data shows homogeneity of the Cu(II)-RLMD samples and green color of the samples confirm existence of Cu(II) ions.

  6. Investigating the secondary structures for long oligonucleotides using attenuated-total-reflection nanoplasmon-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Chiu, K.-C.; Yu, L.-Y.; Lin, C.-Y.; Chen, S.-J.

    2007-09-01

    This study utilizes a nanoplasmon-enhanced Raman scattering based on the attenuated-total-reflection (ATR) method to investigate the secondary structures of long oligonucleotides and their influence on the DNA hybridization. It is found that the ring-breathing modes of adenine, thymine, guanine, and cytosine in Raman fingerprint associated with three 60mer oligonucleotides with prominent secondary structures are lower than those observed for the two oligonucleotides with no obvious secondary structures. It is also determined that increasing the DNA hybridization temperature from 35 °C to 45 °C reduces secondary structure effects. The kinetics of biomolecular interaction analysis can be performed by using surface plasmons resonance biosensor, but the structural information of the oligonucleotides can not observed directly. The ATR-Raman spectrum can provide the structural information of the oligonucleotide monolayer on the sensing surface with the help of a silver patterned nanostructure film based on the finite-difference time-domain simulation and the e-beam lithography fabrication adapted as an ATR-Raman active substrate.

  7. 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)

  8. MIR-ATR sensor for process monitoring

    NASA Astrophysics Data System (ADS)

    Geörg, Daniel; Schalk, Robert; Methner, Frank-Jürgen; Beuermann, Thomas

    2015-06-01

    A mid-infrared attenuated total reflectance (MIR-ATR) sensor has been developed for chemical reaction monitoring. The optical setup of the compact and low-priced sensor consists of an IR emitter as light source, a zinc selenide (ZnSe) ATR prism as boundary to the process, and four thermopile detectors, each equipped with an optical bandpass filter. The practical applicability was tested during esterification of ethanol and formic acid to ethyl formate and water as a model reaction with subsequent distillation. For reference analysis, a Fourier transform mid-infrared (FT-MIR) spectrometer with diamond ATR module was applied. On-line measurements using the MIR-ATR sensor and the FT-MIR spectrometer were performed in a bypass loop. The sensor was calibrated by multiple linear regression in order to link the measured absorbance in the four optical channels to the analyte concentrations. The analytical potential of the MIR-ATR sensor was demonstrated by simultaneous real-time monitoring of all four chemical substances involved in the esterification and distillation process. The temporal courses of the sensor signals are in accordance with the concentration values achieved by the commercial FT-MIR spectrometer. The standard error of prediction for ethanol, formic acid, ethyl formate, and water were 0.38 mol L  -  1, 0.48 mol L  -  1, 0.38 mol L  -  1, and 1.12 mol L  -  1, respectively. A procedure based on MIR spectra is presented to simulate the response characteristics of the sensor if the transmission ranges of the filters are varied. Using this tool analyte specific bandpass filters for a particular chemical reaction can be identified. By exchanging the optical filters, the sensor can be adapted to a wide range of processes in the chemical, pharmaceutical, and beverage industries.

  9. Measuring Photochemical Kinetics in Submonolayer Films by Transient ATR Spectroscopy on a Multimode Planar Waveguide

    SciTech Connect

    Simon, Anne M.; Marucci, Nicole E.; Saavedra, S. Scott

    2011-07-15

    Understanding the kinetics of reactions in molecular thin films can aid in the molecular engineering of organic photovoltaics and biosensors. Using two analytical methods, transient absorbance spectroscopy (TAS) and attenuated total reflectance (ATR), in a relatively simple arrangement when compared with previous TAS/ATR instruments to interrogate molecular structure and photochemistry at interfaces. The multimode planar waveguide geometry provides a significant path length enhancement relative to a conventional transmission geometry, making it feasible to perform measurements on low-surface-coverage films. This work demonstrates that TAS/ATR can be used to probe structure and photochemical kinetics in molecular films at extremely low surface coverages.

  10. 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.

  11. [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/Apol collected by ATR-FTIR method could perform the undamaged and rapid identification for shark fins. PMID:25970896

  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 fast determination of gasoline induction period, and of a positive meaning in the evaluation of fuel quality. PMID:25752033

  13. 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. PMID:26920292

  14. Infrared reflection and attenuated total reflection spectra in the Bi2Se3 topological insulator

    NASA Astrophysics Data System (ADS)

    Novikova, N. N.; Yakovlev, V. A.; Kucherenko, I. V.

    2015-08-01

    Infrared reflection and attenuated total reflection spectra are measured in the (111)Si/Bi2Se3 topological insulator film. The characteristic parameters of plasmons and phonons in the near-surface layers close to the Si-film interface are obtained from the dispersion analysis of the reflection spectra. It is found that the charge carrier density near the interface far exceeds that in the bulk. The dispersion laws for surface polaritons and waveguide modes are determined.

  15. Dielectric interlayers for increasing the transparency of metal films for mid-infrared attenuated total reflection spectroscopy.

    PubMed

    Reithmeier, Martina; Erbe, Andreas

    2010-11-28

    By depositing a continuous, thin metal film on a substrate coated with a mid-infrared (IR) transparent dielectric film that fulfils the role of an index-matching, anti-reflective coating for the metal, the transparency of the metal in the IR wavelength range can be significantly enhanced. This effect is used to yield enhanced absorption in attenuated total internal reflection infrared (ATR-IR) spectroscopy in the presence of continuous thin metal films. The main limitation of the ATR technique when using continuous metal films is the low transparency of metals, especially for infrared light. Computations and experiments show an enhancement in the absorbance of a sample in contact with the metal at certain wavenumbers when the dielectric interlayer is present. The realisation of the setup is the stratified system consisting of zinc selenide-germanium (~1 ?m)-gold (40 nm and 20 nm) using the organic solvent acetonitrile as sample. Enhancement is stronger in s- than in p-polarisation. In s-polarisation, enhancement factors of up to 4 have been observed so far in experiments, but calculations show a route to higher enhancements. In addition to the increased absorption, the absorbance spectra show interference fringes which are due to a mismatch in the real part of the refractive index of the sample in contact with the metal film compared to a reference measurement. PMID:20941445

  16. 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.

  17. 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

  18. Noninvasive method for the assessment of dermal uptake of pesticides using attenuated total reflectance infrared spectroscopy.

    PubMed

    Carden, Angela; Yost, Michael G; Fenske, Richard A

    2005-03-01

    Dermal absorption of pesticides is a primary exposure route for agricultural workers, but is not well characterized. Current measurement techniques are either invasive, such as tape-stripping, or require extensive sample preparation or analysis time, such as urinary metabolite monitoring or wipe sampling followed by gas chromatography analysis. We present the application of a noninvasive, spectroscopic approach for the measurement of pesticide absorption into skin. Attenuated total reflectance infrared spectroscopy (ATR-IR) was used to monitor directly the absorption of two pesticides--captan and azinphos-methyl--in ten volunteers over 20 min under occlusive conditions. We found substantial variability in absorption across subjects. Our results were comparable to those measured by the more traditional method of wipe-sampling followed by extraction and gas chromatography analysis. Multivariate data analysis, in the form of multivariate curve resolution (MCR), is a novel addition to this type of experiment, yielding time-resolved information unachievable by standard methods. These data are potentially more informative than the monitoring of blood or urinary metabolites because they can be acquired in essentially real-time, allowing observations of pesticide absorption on a rapid timescale rather than over hours or days. PMID:15901309

  19. 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. PMID:20132604

  20. 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. PMID:17590027

  1. Cell-substrate contacts illuminated by total internal reflection fluorescence.

    PubMed

    Axelrod, D

    1981-04-01

    A technique for exciting fluorescence exclusively from regions of contact between cultured cells and the substrate is presented. The technique utilizes the evanescent wave of a totally internally reflecting laser beam to excite only those fluorescent molecules within one light wavelength or less of the substrate surface. Demonstrations of this technique are given for two types of cell cultures: rat primary myotubes with acetylcholine receptors labeled by fluorescent alpha-bungarotoxin and human skin fibroblasts labeled by a fluorescent lipid probe. Total internal reflection fluorescence examination of cells appears to have promising applications, including visualization of the membrane and underlying cytoplasmic structures at cell-substrate contacts, dramatic reduction of autofluorescence from debris and thick cells, mapping of membranes topography, and visualization of reversible bound fluorescent ligands at membrane receptors. PMID:7014571

  2. 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

  3. 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.

  4. 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.

  5. X-Ray Reflectometry and Total Reflection Imaging

    NASA Astrophysics Data System (ADS)

    Jibaoui, H.; Erre, D.

    X-ray specular reflectivity measurement is a powerful method for investigating surfaces, and the shape analysis of the X-ray reflectivity curve provides a range of possibilities for the study of surface structure, thin layers and multilayers. The wide field applications of this technique in modern technology explains its increasing use. The typical equipment for this technique is usually a reflectometer with an angular scanning that requires a long time for studying a surface size of a few mm2. This article proposes a new method for simultaneous detection of several experimental reflectivity curves without incidence angle scanning and thus with a shorter aquisition time, typically 2-60 s. The method is illustrated with a first experiment using a divergent X-ray beam and a 2D detector. Furthermore, such an approach provides a new imaging technique for the surface and interface. The images obtained that way can concern the direct visualization of isolated defects sited on a very flat surface or buried interface; a domain where the X-ray reflectivity cannot be used. The feasibility of X-ray images at grazing incidence has also been demonstrated. The technique will hereafter be noted as total reflection X-ray microscopy (TRXRM).

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

    PubMed

    Barnette, Anna L; Kim, Seong H

    2012-11-01

    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. PMID:23098071

  7. In situ permeation study of drug through the stratum corneum using attenuated total reflectance [corrected] Fourier transform infrared spectroscopic imaging.

    PubMed

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

    2009-01-01

    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 reflectance [corrected] (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. PMID:19566304

  8. Investigating the structural changes of β-amyloid peptide aggregation using attenuated-total-reflection surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chiu, K.-C.; Yu, L.-Y.; Yih, J.-N.; Chen, S.-J.

    2007-02-01

    This study utilizes a surface-enhanced Raman spectroscopy (SERS) based on the attenuated-total-reflection (ATR) method to investigate that the structural information of the biomolecular monolayer on sensing surface can be dynamically observed with a higher signal-to-noise ratio signal. The secondary structures of long oligonucleotides and their influence on the DNA hybridization on the sensing surface are investigated. The SERS spectrum provides the structural information of the oligonucleotides with the help of a silver colloidal nanoparticle monolayer by control of the size and distribution of the nanoparticles adapted as a Raman active substrate. It is found that the ring-breathing modes of adenine, thymine, guanine, and cytosine in Raman fingerprint associated with three 60mer oligonucleotides with prominent secondary structures are lower than those observed for the two oligonucleotides with no obvious secondary structures. It is also determined that increasing the DNA hybridization temperature from 35°C to 45°C reduces secondary structure effects. The ATR-SERS biosensing technique will be used to provide valuable structural information regarding the short-term reversible interactions and long-term polymerization events in the Aβ aggregates on the sensing surface.

  9. Polarization model for total internal reflection-based retroreflectors

    NASA Astrophysics Data System (ADS)

    Zhu, Minhao; Li, Yan; Ellis, Jonathan D.

    2014-06-01

    A theoretical model has been developed to analyze the output polarization state of a total internal reflection-based retroreflector as a function of pitch and yaw motions. There are six different beam paths in the retroreflector, and thus output polarization states, for a given pitch or yaw misalignment. This polarization model discusses the electric field changes of the laser beam based on Fresnel equations for phase and polarization change on reflection. Jones matrices are computed based on Snell's law, Fresnel equations, the solid geometry, and coordinate transformations to obtain a Jones matrix model of the retroreflector for a given misalignment. Modeling results show that there is always a rotation to the input beam's polarization and there are specific input regions that are not sensitive to pitch motions but are sensitive to yaw motions. Validation of the model is also presented, using both theoretical and experimental results published by Kalibjian in 2004.

  10. 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

  11. Discrimination of the hard keratins animal horn and chelonian shell using attenuated total reflection-infrared spectroscopy.

    PubMed

    Biscardi, Brianna; Welsh, Wendy; Kennedy, Anthony

    2012-05-01

    The ability to discriminate between objects manufactured from animal horn and chelonian (turtle, tortoise, or terrapin) shell is important from a cultural and archeological perspective such that it may allow conservators to determine the appropriate treatment and long-term care solution. It would also aid curators in identifying and cataloging items manufactured from these materials. Discrimination and classification is also a valuable tool for those involved in tracking the illegal trade in restricted materials of this nature. Attenuated total reflection infrared (ATR-IR) spectroscopy, using a single reflection diamond internal reflection element (IRE), coupled with discrimination analysis was used to analyze a total of thirty-nine samples (29 calibration samples, 10 validation samples). A discrimination analysis model was constructed using Mahalanobis distances to classify spectra into one of two classes. The model was then subsequently used to successfully classify all validation samples and correctly identify them as animal horn or chelonian shell based on second-derivative spectra of the amide I and II regions. This technique requires minimal to no sample preparation and may be used to nondestructively identify very small samples successfully without performing detailed secondary structural curve-fitting routines. This model should be a valuable resource to museums, conservators, and wildlife management programs for rapidly and reliably discriminating between animal horn and chelonian shell. PMID:22524968

  12. Effects of thermal gradients on total internal reflection corner cubes.

    PubMed

    Goodrow, Scott D; Murphy, Thomas W

    2012-12-20

    Uncoated corner cube retroreflectors (CCRs) operating via total internal reflection (TIR) are less susceptible to internal heating than their metal-coated analogs, lacking an absorber on the rear surface. Even so, environments that induce differential heating within the CCR will result in thermal lensing of the incident wavefront, introducing aberrations that will generally reduce the central irradiance of the polarization-sensitive far-field diffraction pattern (FFDP). In this paper, we characterize the sensitivity of TIR CCRs to axial and radial thermal gradients. We present simulated FFDPs for key input polarizations and incidence angles and provide a generalized analytic model that approximates the behavior of the central irradiance as temperature differences are introduced. PMID:23262618

  13. Total Internal Reflection Fluorescence (TIRF) Microscopy of Chlamydomonas Flagella

    PubMed Central

    Engel, Benjamin D.; Lechtreck, Karl-Ferdinand; Sakai, Tsuyoshi; Ikebe, Mitsuo; Witman, George B.; Marshall, Wallace F.

    2013-01-01

    The eukaryotic flagellum is host to a variety of dynamic behaviors, including flagellar beating, the motility of glycoproteins in the flagellar membrane, and intraflagellar transport (IFT), the bidirectional traffic of protein particles between the flagellar base and tip. IFT is of particular interest, as it plays integral roles in flagellar length control, cell signaling, development, and human disease. However, our ability to understand dynamic flagellar processes such as IFT is limited in large part by the fidelity with which we can image these behaviors in living cells. This chapter introduces the application of total internal reflection fluorescence (TIRF) microscopy to visualizing the flagella of Chlamydomonas reinhardtii. The advantages and challenges of TIRF are discussed in comparison to confocal and differential interference contrast (DIC) techniques. This chapter also reviews current IFT insights gleaned from TIRF microscopy of Chlamydomonas and provides an outlook on the future of the technique, with particular emphasis on combining TIRF with other emerging imaging technologies. PMID:20409817

  14. Total Internal Reflection Fluorescence Quantification of Receptor Pharmacology

    PubMed Central

    Fang, Ye

    2015-01-01

    Total internal reflection fluorescence (TIRF) microscopy has been widely used as a single molecule imaging technique to study various fundamental aspects of cell biology, owing to its ability to selectively excite a very thin fluorescent volume immediately above the substrate on which the cells are grown. However, TIRF microscopy has found little use in high content screening due to its complexity in instrumental setup and experimental procedures. Inspired by the recent demonstration of label-free evanescent wave biosensors for cell phenotypic profiling and drug screening with high throughput, we had hypothesized and demonstrated that TIRF imaging is also amenable to receptor pharmacology profiling. This paper reviews key considerations and recent applications of TIRF imaging for pharmacology profiling. PMID:25922915

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

    PubMed

    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 degrees-75.5 degrees, with a 0.05 degrees 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. PMID:20441324

  16. Direct analysis of oxidizing agents in aqueous solution with attenuated total reflectance mid-infrared spectroscopy and diamond-like carbon protected waveguides.

    PubMed

    Janotta, Markus; Vogt, Frank; Voraberger, Hannes-Stefan; Waldhauser, Wolfgang; Lackner, Jrgen M; Stotter, Christoph; Beutl, Michael; Mizaikoff, Boris

    2004-01-15

    A novel approach for the direct detection of oxidizing agents in aqueous solution is presented using diamond-like carbon (DLC) protected waveguides in combination with attenuated total reflectance (ATR) mid-infrared spectroscopy. Pulsed laser deposition was applied to produce high-quality DLC thin films on ZnSe ATR crystals with thicknesses of a few 100 nm. Scanning electron microscopy and X-ray photoelectron spectroscopy has been used to investigate the surface properties of the DLC films including the sp(3)/sp(2) hybridization ratio of the carbon bonds. Beside excellent adhesion of the DLC coatings to ZnSe crystals, these films show high chemical stability against strongly oxidizing agents. IR microscopy was utilized to compare differences in the chemical surface modification of bare and protected ATR waveguides when exposed to hydrogen peroxide, peracetic acid, and peroxydisulfuric acid. The feasibility of DLC protected waveguides for real-time concentration monitoring of these oxidizing agents was demonstrated by measuring calibration sets in a concentration range of 0.2-10%. Additionally, principal component regression has been applied to analyze multicomponent mixtures of hydrogen peroxide, acetic acid, and peracetic acid in aqueous solution. Due to high chemical stability and accurate monitoring capabilities, DLC protected waveguides represent a novel approach for directly detecting oxidizing agents in aqueous solution with promising potential for industrial process analysis. PMID:14719887

  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

    2013-06-01

    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. PMID:23565977

  18. 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. PMID:25582569

  19. 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

  20. 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

    2016-01-01

    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

  1. 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. PMID:26810185

  2. Absolute position total internal reflection microscopy with an optical tweezer

    PubMed Central

    Liu, Lulu; Woolf, Alexander; Rodriguez, Alejandro W.; Capasso, Federico

    2014-01-01

    A noninvasive, in situ calibration method for total internal reflection microscopy (TIRM) based on optical tweezing is presented, which greatly expands the capabilities of this technique. We show that by making only simple modifications to the basic TIRM sensing setup and procedure, a probe particle’s absolute position relative to a dielectric interface may be known with better than 10 nm precision out to a distance greater than 1 μm from the surface. This represents an approximate 10× improvement in error and 3× improvement in measurement range over conventional TIRM methods. The technique’s advantage is in the direct measurement of the probe particle’s scattering intensity vs. height profile in situ, rather than relying on assumptions, inexact system analogs, or detailed knowledge of system parameters for calibration. To demonstrate the improved versatility of the TIRM method in terms of tunability, precision, and range, we show our results for the hindered near-wall diffusion coefficient for a spherical dielectric particle. PMID:25512542

  3. Total internal reflection photoacoustic spectroscopy for the detection of ?-hematin.

    PubMed

    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, ?-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. PMID:22734742

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

    PubMed

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

    2009-11-10

    Total internal reflection fluorescence (TIRF) microscopy uses the evanescent field on the aqueous side of a glass/aqueous interface to selectively illuminate fluorophores within approximately 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 approximately 50 nm deep evanescent field. PMID:19904308

  5. Total internal reflection photoacoustic spectroscopy for the detection of ?-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, ?-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.

  6. Visualizing membrane trafficking using total internal reflection fluorescence microscopy.

    PubMed

    Beaumont, V

    2003-08-01

    There is a dizzying array of fluorescent probes now commercially available to monitor cellular processes, and advances in molecular biology have highlighted the ease with which proteins can now be labelled with fluorophores without loss of functionality. This has led to an explosion in the popularity of fluorescence microscopy techniques. One such specialized technique, total internal reflection fluorescence microscopy (TIR-FM), is ideally suited to gaining insight into events occurring at, or close to, the plasma membrane of live cells with excellent optical resolution. In the last few years, the application of TIR-FM to membrane trafficking events in both non-excitable and excitable cells has been an area of notable expansion and fruition. This review gives a brief overview of that literature, with emphasis on the study of the regulation of exocytosis and endocytosis in excitable cells using TIR-FM. Finally, recent applications of TIR-FM to the study of cellular processes at the molecular level are discussed briefly, providing promise that the future of TIR-FM in cell biology will only get brighter. PMID:12887313

  7. Combined study of biphasic and zero-order release formulations with dissolution tests and ATR-FTIR spectroscopic imaging.

    PubMed

    Wray, Patrick; Li, Jing; Li, Ling Qiao; Kazarian, Sergei G

    2014-07-01

    In this study of multi-layer tablets, the dissolution of biphasic and zero-order release formulations has been studied primarily using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic imaging as well as UV-Vis detection of dissolved drug in the effluent stream and USP dissolution testing. Bilayer tablets, containing the excipients microcrystalline cellulose (MCC) and glucose, were used for biphasic release with nicotinamide and buflomedil as model drugs. ATR-FTIR spectroscopic imaging showed the changing component distributions during dissolution. Further experiments studied monolithic and barrier-layered tablets containing hydroxypropyl methylcellulose, MCC and buflomedil dissolving in a USP I apparatus. These data were compared with UV-Vis dissolution profiles obtained online with the ATR flow-through cell. ATR-FTIR imaging data of the biphasic formulations demonstrated that the drug release was affected by excipient ratios and effects such as interference between tablet sections. Tablets placed in the ATR-FTIR flow-through cell exhibited zero-order UV-Vis dissolution profile data at high flow rates, similar to barrier-layered formulations studied using the USP I apparatus. ATR-FTIR spectroscopic imaging provided information regarding the dissolution mechanisms in multi-layer tablets which could assist formulation development. The ability to relate data from USP dissolution tests with that from the ATR-FTIR flow-through cell could help spectroscopic imaging complement dissolution methods used in the industry. PMID:24801351

  8. 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

    2014-10-01

    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. PMID:25203136

  9. 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 110 11 and 110 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.

  10. Oxidation of carbon monoxide at a platinum film electrode studied by Fourier transform infrared spectroscopy with attenuated total reflection technique

    SciTech Connect

    Zhu, Yimin; Uchida, Hiroyuki; Watanabe, Masahiro

    1999-12-07

    Fourier transform infrared reflection absorption spectroscopy with the attenuated total reflection technique (ATR-FTIR), coupled with cyclic voltammetry (CV) measurement, is used to observe the oxidation process of adsorbed CO at Pt film sputtered on a silicon prism. The interesting bipolar shape of the linearly bonded CO band is observed at high coverage of CO, although no CO band is included in the reference spectrum. This asymmetric shape is ascribed to Fano resonance. In addition to a linear CO and bridged CO, a new absorption band presumably assigned to a carboxyl radical, was detected. This band may be formed by a heterogeneous reaction between adsorbed CO and H{sub 2}O on the Pt surface in the hydrogen adsorption potential region. The adsorbed carboxyl radical was oxidized at a less positive potential than the adsorbed CO, which can be ascribed to a presumable origin for the pre-peak that appeared in a CV reading prior to the oxidation of such a linear or bridged CO. This oxidation led to the rearrangement of CO ad-layers, especially at high coverage of CO. In the case of the low coverage of CO, the conversion from the bridged CO to the linear CO is ascribed to the potential induced electronic effects of the electrode surface on the adsorption states. A consumption of adsorbed H{sub 2}O and a production of CO{sub 2} were also clearly indicated by the spectroscopy when COOH of CO disappeared from the surface.

  11. Nitrogen-doped diamond-like carbon as optically transparent electrode for infrared attenuated total reflection spectroelectrochemistry.

    PubMed

    Menegazzo, Nicola; Kahn, Markus; Berghauser, Roswitha; Waldhauser, Wolfgang; Mizaikoff, Boris

    2011-05-01

    This contribution describes the development of nitrogen-doped diamond-like carbon (N-DLC) thin films for multi-reflection mid-infrared (MIR) attenuated total reflectance (IR-ATR) spectroelectrochemistry. N-DLC coatings were deposited using pulsed laser deposition (PLD) involving the ablation of a high purity graphite target. The DLC matrix was further modified by ablating the target in the presence of nitrogen gas. This technique offers the advantage of depositing thin films at room temperature, thereby enabling coating of temperature-sensitive substrates including e.g., MIR waveguides. The resulting films were analyzed with X-ray photoelectron spectroscopy (XPS), and determined to be composed of carbon, nitrogen, and adventitious oxygen. Raman spectroscopic studies indicate that the addition of nitrogen induces further clustering and ordering of the sp(2)-hybridized carbon phase. The electrochemical activity of PLD fabricated N-DLC films was verified using the Ru(NH(3))(3+/2+) redox couple, and was determined to be comparable with that of other carbon-based electrodes. In situ spectroelectrochemical studies involving N-DLC coated zinc selenide (ZnSe) MIR waveguides provided evidence concerning the oxidation of N-DLC at anodic potentials in 1 M HClO(4) solutions. Finally, the electropolymerization of polyaniline (PAni) was performed at N-DLC-modified waveguide surfaces, which enabled spectroscopic monitoring of the electropolymerization, as well as in situ studying the structural conversion of PAni at different potentials. PMID:21373709

  12. Use of attenuated total reflectance midinfrared for rapid and real-time analysis of compositional parameters in commercial white grape juice.

    PubMed

    Shah, Nevil; Cynkar, Wies; Smith, Paul; Cozzolino, Daniel

    2010-03-24

    A simple and fast midinfrared (MIR) spectroscopy method was developed for simultaneously determining total soluble solids (TSS, degrees Brix), pH, total phenolics, ammonia, free amino nitrogen (FAN), and yeast assimilable nitrogen (YAN) contents in grape juice samples using attenuated total reflectance (ATR). Results from this study demonstrated the capability of ATR-MIR coupled with partial least-squares regression to measure TSS and pH and to monitor FAN, ammonia, and YAN in a wide range of grape juice samples. The standard error in cross-validation and the residual predictive deviation obtained were 0.20 degrees Brix and 9 for TSS, 0.07 and 3.3 for pH, 14.8 mg/L and 2 for ammonia, 28.3 mg/L and 2 for FAN, and 36.9 mg/L and 2 for YAN, respectively. Both the time of analysis and the volume of sample required were considerably reduced as compared to the transmission MIR measurements currently used by the wine industry. PMID:20170170

  13. 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.

  14. 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.

  15. Electronic transitions of protonated and deprotonated amino acids in aqueous solution in the region 145-300 nm studied by attenuated total reflection far-ultraviolet spectroscopy.

    PubMed

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

    2013-03-28

    The electronic transitions of 20 naturally occurring amino acids in aqueous solution were studied with attenuated total reflection far-ultraviolet (ATR-FUV) spectroscopy in the region from 145 to 300 nm. From the measured ATR spectra of sample solutions, the FUV absorption spectra attributed to the amino acids were separated from the intense solvent absorption by using a modified Kramers-Kronig transformation method. The FUV absorption spectra of the amino acids reflect the protonation states of the backbone and side-chain structures. The contributions of the side chains to the spectra were also examined from the difference spectra subtracting the corresponding Gly spectrum from each spectrum. The observed spectra were compared mostly with the electronic transition studies of the molecular fragments of the amino acids in gas phase. The FUV spectra of the amino acids exhibited the intra- and intermolecular electronic interactions of the solute-solute as well as the solute-solvent, and those are essential factors to elucidate UV photochemical processes of the amino acids in aqueous solution. PMID:23458581

  16. Infrared spectroscopy with heated attenuated total internal reflectance enabling precise measurement of thermally induced transitions in complex biological polymers.

    PubMed

    Warren, Frederick J; Perston, Benjamin B; Royall, Paul G; Butterworth, Peter J; Ellis, Peter R

    2013-04-16

    We report an improved tool for acquiring temperature-resolved fourier transform infrared (FT-IR) spectra of complex polymer systems undergoing thermal transitions, illustrated by application to several phenomena related to starch gelatinization that have proved difficult to study by other means. Starch suspensions from several botanical origins were gelatinized using a temperature-controlled attenuated total reflectance (ATR) crystal, with IR spectra collected every 0.25 °C. By following the 995/1022 cm(-1) peak ratio, clear transitions occurring between 59 and 70 °C were observed, for which the midpoints could be determined accurately by sigmoidal fits. The magnitude of the change in peak ratio was found to be strongly correlated to the enthalpy of gelatinization as measured by differential scanning calorimetry (DSC, R(2) = 0.988). An important advantage of the technique, compared to DSC, is that the signal-to-noise ratio is not reduced when measuring very broad transitions. This has the potential to allow more precise determination of the gelatinization parameters of high-amylose starches, for which gelatinization may take place over several tens of °C. PMID:23461675

  17. 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.

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

    PubMed

    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. PMID:22352668

  19. 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.; ?ojewski, T.; ?ojewska, 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 ?-sheet to antiparallel ?-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.

  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; Gldenhaupt, Jrn; Mavarani, Laven; Nabers, Andreas; Gerwert, Klaus; Ktting, 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 Frster resonance energy transfer (FRET) signal demonstrated a large protein-protein distance, indicating an even distribution of the protein within the dextran. PMID:26102158

  1. The influence of wetting and drying cycles on mid-infrared attenuated total-reflection spectra of quartz: understanding spectroscopy of disturbed soil

    NASA Astrophysics Data System (ADS)

    Karlowatz, Manfred; Aleksandrov, Alexandr; Orlando, Thomas; Cathcart, J. Michael; Mizaikoff, Boris

    2004-09-01

    Attenuated total reflection (ATR) spectroscopy is a well established optical technique investigating fundamental molecular vibrations in the mid-infrared (MIR) spectral regime for a wide variety of samples including liquids, thin films and powders. In the present study, first results simulating the influence of weathering processes on the spectral characteristics of soils are discussed. In particular, the effect of wetting and drying cycles on IR spectra of fine quartz (SiO2) powders has been investigated with ATR techniques. Resulting from a wetting and drying cycle, the sample spectra of quartz powders revealed significantly increased absorption intensities throughout the spectral region of interest (1400-600 cm-1). We hypothesize that this effect results from a higher packing density of the particles following the wetting procedure with the fines packed into interstitial spaces closer to the ATR waveguide surface. Moreover, a strong red shift of approx. 40 cm-1 of the absorption band assigned to asymmetric SiO4 stretching vibrations (1050 cm-1 to 1250 cm-1) could be observed. Both effects, increase in intensity and spectral shift, are reversed by mechanically disturbing the cemented powder after the wetting/drying cycle. Experiments with s- and p-polarized infrared radiation show similar (reversible) spectral shifts for this particular frequency range. It is expected that these findings will lead to better understanding of the spectral characteristics of soil in the mid-infrared spectral domain providing improved interpretation of data retrieved from disturbed soils e.g. potential landmine sites during hyperspectral imaging.

  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. 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.

  4. Fourier transform infrared attenuated total reflection analysis of human hair: comparison of hair from breast cancer patients with hair from healthy subjects.

    PubMed

    Lyman, Donald J; Murray-Wijelath, Jacqueline

    2005-01-01

    A comparative study of Fourier transform infrared attenuated total reflection (FTIR-ATR) spectra of 32 scalp and pubic hair samples from individuals diagnosed with breast cancer and those who were negative for breast cancer showed increases in the beta-sheet/disorder structures (relative to alpha-helix structures) and C-H lipid content of hair from breast cancer patients. Thus, the presence of breast cancer appears to alter the hair growth process, resulting in changes in the composition and conformation of cell membrane and matrix materials of hair fiber. These appear to be consistent with the changes observed in X-ray diffraction patterns for hair from breast cancer patients. A blind study of 12 additional hair samples using these FTIR-ATR spectral differences as markers correctly identified all four hair samples from cancer patients (100%). Two of these samples were from breast cancer patients. Of the remaining two samples analyzing positive for cancer, one was from a prostate cancer patient and one from a lung cancer patient. Thus, it appears that the mechanism that alters hair fiber synthesis in the three types of cancer may be similar. The blind study incorrectly identified as positive for cancer three hair samples from two apparently healthy individuals and one patient considered cured from prostate cancer. PMID:15720735

  5. Drug penetration as studied by noninvasive methods: fourier transform infrared-attenuated total reflection, fourier transform infrared, and ultraviolet photoacoustic spectroscopy.

    PubMed

    Hanh, B D; Neubert, R H; Wartewig, S; Christ, A; Hentzsch, C

    2000-09-01

    The penetration of the drugs dithranol and methoxsalen from semisolid Vaseline formulation into an artificial dodecanol-collodion membrane was followed by three spectroscopic methods; they are, step-scan Fourier transform infrared (FTIR) photoacoustic spectroscopy (PAS) with phase modulation, FTIR-attenuated total reflection (FTIR-ATR), and ultraviolet (UV) PAS. The uptake of the drug in the membrane was quantified by monitoring the dependence of an appropriate drug band on the penetration time. The PAS experiments were carried out with various modulation frequencies for generating various sampling depths. Based on Fick's second law, the diffusion coefficient was derived by numerical fitting of the experimental data. It appears that the diffusion coefficient for the drug in the membrane depends on the distance. The comparative studies demonstrate that FTIR-ATR is favored for permeation studies, whereas the PAS techniques are capable of providing the drug penetration profile in the membrane. Thus, extended experimental data are available for new insight into the penetration process. However, because of the photacoustic cells at hand, PAS is only suitable for in vitro studies. PMID:10944375

  6. 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.; Kpper, 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 ?g/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.

  7. Application of multivariate chemometric techniques for simultaneous determination of five parameters of cottonseed oil by single bounce attenuated total reflectance Fourier transform infrared spectroscopy.

    PubMed

    Talpur, M Younis; Kara, Huseyin; Sherazi, S T H; Ayyildiz, H Filiz; Topkafa, Mustafa; Arslan, Fatma Nur; Naz, Saba; Durmaz, Fatih; Sirajuddin

    2014-11-01

    Single bounce attenuated total reflectance (SB-ATR) Fourier transform infrared (FTIR) spectroscopy in conjunction with chemometrics was used for accurate determination of free fatty acid (FFA), peroxide value (PV), iodine value (IV), conjugated diene (CD) and conjugated triene (CT) of cottonseed oil (CSO) during potato chips frying. Partial least square (PLS), stepwise multiple linear regression (SMLR), principal component regression (PCR) and simple Beer׳s law (SBL) were applied to develop the calibrations for simultaneous evaluation of five stated parameters of cottonseed oil (CSO) during frying of French frozen potato chips at 170°C. Good regression coefficients (R(2)) were achieved for FFA, PV, IV, CD and CT with value of >0.992 by PLS, SMLR, PCR, and SBL. Root mean square error of prediction (RMSEP) was found to be less than 1.95% for all determinations. Result of the study indicated that SB-ATR FTIR in combination with multivariate chemometrics could be used for accurate and simultaneous determination of different parameters during the frying process without using any toxic organic solvent. PMID:25127621

  8. ATR neutron spectral characterization

    SciTech Connect

    Rogers, J.W.; Anderl, R.A.

    1995-11-01

    The Advanced Test Reactor (ATR) at INEL provides intense neutron fields for irradiation-effects testing of reactor material samples, for production of radionuclides used in industrial and medical applications, and for scientific research. Characterization of the neutron environments in the irradiation locations of the ATR has been done by means of neutronics calculations and by means of neutron dosimetry based on the use of neutron activation monitors that are placed in the various irradiation locations. The primary purpose of this report is to present the results of an extensive characterization of several ATR irradiation locations based on neutron dosimetry measurements and on least-squares-adjustment analyses that utilize both neutron dosimetry measurements and neutronics calculations. This report builds upon the previous publications, especially the reference 4 paper. Section 2 provides a brief description of the ATR and it tabulates neutron spectral information for typical irradiation locations, as derived from the more historical neutron dosimetry measurements. Relevant details that pertain to the multigroup neutron spectral characterization are covered in section 3. This discussion includes a presentation on the dosimeter irradiation and analyses and a development of the least-squares adjustment methodology, along with a summary of the results of these analyses. Spectrum-averaged cross sections for neutron monitoring and for displacement-damage prediction in Fe, Cr, and Ni are given in section 4. In addition, section4 includes estimates of damage generation rates for these materials in selected ATR irradiation locations. In section 5, the authors present a brief discussion of the most significant conclusions of this work and comment on its relevance to the present ATR core configuration. Finally, detailed numerical and graphical results for the spectrum-characterization analyses in each irradiation location are provided in the Appendix.

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

    PubMed

    Saucedo-Hernndez, Yanelis; Lerma-Garca, Mara Jess; Herrero-Martnez, Jos Manuel; Ramis-Ramos, Guillermo; Jorge-Rodrguez, Elisa; Sim-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. PMID:21410160

  10. Detection and Quantification of Early-Stage Malaria Parasites in Laboratory Infected Erythrocytes by Attenuated Total Reflectance Infrared Spectroscopy and Multivariate Analysis

    PubMed Central

    2014-01-01

    New diagnostic modalities for malaria must have high sensitivity and be affordable to the developing world. We report on a method to rapidly detect and quantify different stages of malaria parasites, including ring and gametocyte forms, using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR) and partial least-squares regression (PLS). The absolute detection limit was found to be 0.00001% parasitemia (<1 parasite/?L of blood; p < 0.008) for cultured early ring stage parasites in a suspension of normal erythrocytes. Future development of universal and robust calibration models can significantly improve malaria diagnoses, leading to earlier detection and treatment of this devastating disease. PMID:24694036

  11. 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. PMID:26190596

  12. Visco-thermal effects in acoustic metamaterials: from total transmission to total reflection and high absorption

    NASA Astrophysics Data System (ADS)

    Molerón, Miguel; Serra-Garcia, Marc; Daraio, Chiara

    2016-03-01

    We theoretically and experimentally investigate visco–thermal effects on the acoustic propagation through metamaterials consisting of rigid slabs with subwavelength slits embedded in air. We demonstrate that this unavoidable loss mechanism is not merely a refinement, but that it plays a dominant role in the actual acoustic response of the structure. Specifically, in the case of very narrow slits, the visco–thermal losses avoid completely the excitation of Fabry–Perot resonances, leading to 100% reflection. This is exactly opposite to the perfect transmission predicted in the idealised lossless case. Moreover, for a wide range of geometrical parameters, there exists an optimum slit width at which the energy dissipated in the structure can be as high as 50%. This work provides a clear evidence that visco–thermal effects are necessary to describe realistically the acoustic response of locally resonant metamaterials.

  13. Investigation on the adsorption characteristics of sodium benzoate and taurine on gold nanoparticle film by ATR-FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kumar, Naveen; Thomas, S.; Tokas, R. B.; Kshirsagar, R. J.

    2014-01-01

    Fourier transform infrared (FTIR) spectroscopic studies of sodium benzoate and taurine adsorbed on gold nanoparticle (AuNp) film on silanised glass slides have been studied by attenuated total reflection technique (ATR). The surface morphology of the AuNp films has been measured by Atomic Force Microscopy. The ATR spectra of sodium benzoate and taurine deposited on AuNp film are compared with ATR spectra of their powdered bulk samples. A new red-shifted band appeared along with the symmetric and asymmetric stretches of carboxylate group of sodium benzoate leading to a broadening of the above peaks. Similar behavior is also seen in the case of symmetric and asymmetric stretches of sulphonate group of taurine. The results indicate presence of both chemisorbed and physisorbed layers of both sodium benzoate and taurine on the AuNp film with bottom layer chemically bound to AuNp through carboxylate and sulphonate groups respectively.

  14. Investigation of drug release from suspension using FTIR-ATR technique: part I. Determination of effective diffusion coefficient of drugs.

    PubMed

    Hanh, B D; Neubert RHH; Wartewig, S

    2000-08-25

    Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy was used to study directly the release of drug particles (ketoconazole) in a liquid medium (paraffinum liquidum). In the case of the release experiment, the formulation is placed on the ATR crystal and the acceptor membrane on the top of the ointment. The decrease of the drug content in the sediment near the interface ATR crystal-formulation in the course of the release process was quantified by monitoring the changes of the IR spectrum in relevant spectral ranges using multivariate analysis. A mathematical model based on Fick's second law with appropriate initial and boundary conditions was applied in order to determine the diffusion coefficient of the drug in the liquid medium. Knowing this value, it is possible to calculate the effective diffusion coefficient of the drug in heterogeneous semisolid formulation (Vaseline) as a function of the volume fraction of the solid phase. PMID:11011998

  15. 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. PMID:21894905

  16. PUREX new substation ATR

    SciTech Connect

    Nelson, D.E.

    1997-05-12

    This document is the acceptance test report (ATR) for the New PUREX Main and Minisubstations. It covers the factory and vendor acceptance and commissioning test reports. Reports are presented for the Main 5 kV substation building, the building fire system, switchgear, and vacuum breaker; the minisubstation control building and switch gear; commissioning test; electrical system and loads inspection; electrical utilities transformer and cable; and relay setting changes based on operational experience.

  17. 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, indicating the formation of contact ion pairs between Na(+) and NO(3)(-). Moreover, in the RH range from approximately 53% down to approximately 26%, two peaks at 836 and 829 cm(-1) were observed in the nu(2)-NO(3)(-) band region, demonstrating the coexistence of NaNO(3) solid particles and droplets. PMID:19044926

  18. Structural investigations of oriented membrane assemblies by FTIR-ATR spectroscopy

    NASA Astrophysics Data System (ADS)

    Fringeli, Urs Peter; Goette, Jeannette; Reiter, Gerald; Siam, Monira; Baurecht, Dieter

    1998-06-01

    In situ attenuated total reflection (ATR) Fourier transform (FT) spectroscopy is presented as an adequate tool for studying molecular structure and function of biomembranes. In this article emphasis was directed to the production of suitable model bilayer membranes for optimum mimicking of natural biomembranes, and to special FTIR ATR techniques to achieve enhanced selectivity as well as time resolved information on complex membrane assemblies. In this context, the preparation of supported bilayers according to the LB/vesicle method is presented and the use of such model membranes to build more complex assemblies, e.g. with creatine kinase, a surface bound enzyme, and alkaline phosphatase, a membrane anchored enzyme. A comprehensive summary of equations used for quantitative ATR spectroscopy is given and applied to determine the surface concentration and orientation of membrane bound molecules. The use of supported bilayers for drug membrane interaction studies is demonstrated by the local anesthetic dibucaine. Besides of structural information's, such studies result also thermodynamic date, such as adsorption isotherm and partition coefficient. A special ATR set-up for more precise background compensation is presented enabling the conversion of a single beam spectrometer into a pseudo double beam spectrometer. This optical component may be placed in the sample compartment of the spectrometer, and is referred to as single-beam-sample-reference (SBSR) attachment. Finally, a short theoretical introduction into time resolved modulation spectroscopy is given. Temperature modulated excitation of reversible conformational changes in the polypeptide poly-L-lysine and the enzyme RNase are shown as examples.

  19. Surface functionalization of germanium ATR devices for use in FTIR-biosensors.

    PubMed

    Devouge, Sabrina; Conti, Josphine; Goldsztein, Andra; Gosselin, Emmanuel; Brans, Alain; Vou, Michel; De Coninck, Jol; Hombl, Fabrice; Goormaghtigh, Erik; Marchand-Brynaert, Jacqueline

    2009-04-15

    Biosensors based on intrinsic detection methods have attracted growing interest. The use of Fourier transform infra-red (FTIR) spectroscopy with the attenuated internal total reflection (ATR) mode, in the biodetection context, requires appropriate surface functionalization of the ATR optical element. Here, we report the direct grafting of a thin organic layer (about 20 A depth) on the surface of a germanium crystal. This covering, constructed with novel amphiphilic molecules 2b (namely, 2,5,8,11,14,17,20-heptaoxadocosan-22-yl-3-(triethoxysilyl) propylcarbamate), is stable for several hours under phosphate buffered saline (PBS) flux and features protein-repulsive properties. Photografting of molecule 5 (namely, O-succinimidyl 4-(p-azidophenyl)butanoate) affords the activated ATR element, ready for the covalent fixation of receptors, penicillin recognizing proteins BlaR-CTD for instance. The different steps of the previous construction have been monitored by water contact angle (theta(w)) measurements, spectroscopic ellipsometry (covering depth), X-ray photoelectron spectroscopy (XPS) by using a fluorinated tag for the control of surface reactivity, and FTIR-ATR spectroscopy for the structural analysis of grafted molecules. Indeed, contrarily to silicon device, germanium device offers a broad spectral window (1000-4000 cm(-1)) and thus amide I and II absorption bands can be recorded. This work lays the foundations for the construction of novel FTIR biosensors. PMID:19150721

  20. Infrared ATR: a probe for cellular activation

    NASA Astrophysics Data System (ADS)

    Timlin, Jerilyn A.; Martin, Laura E.; Alam, M. Kathleen; Haaland, David M.; Garrison, Kristen; Lyons, C. Richard; Hjelle, Brian

    2002-02-01

    We employ infrared spectroscopy (IR) with attenuated total reflectance (ATR) as a sampling technique to monitor live and dried RAW cells (a murine macrophage cell line) during activation with g-interferon and lipopolysaccharide. By comparing the spectra of activated cells at various time points to the spectra of healthy control cells, we identify spectral bands associated with nucleic acids that are markers for the cell activation process. These spectral changes are slight and can be complicated with the normal metabolic changes that occur within cells. We will discuss the use of data pretreatment strategies to accurately correct for the contribution of the buffer to the live cell spectra. We find the standard background correction method inadequate for concentrated solutions of cells. Data presented shows the severe effect incorrect background subtraction has on the cell spectra. We report a more accurate correction for phosphate buffer spectral contribution using an interactive subtraction of the buffer spectrum. We will show classification of dried control and activated macrophage cell spectra using partial-least squares analysis with multiplicative scatter correction.

  1. 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%.

  2. 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, Lus 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 (?C?C of TCA ring) and 1314 cm1 (a shifted ?CC of TCA) and an increase in the relative intensities of the bands at ?1039 cm1 (?CO of polysaccharides) and ?813 cm1 (?CH of suberin), the latter by overlapping with intense bands of TCA. These relative intensities were evaluated in comparison to a fingerprint of suberin (?asCOC), at 1161 cm1. 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. PMID:25487962

  3. Dynamical measurement of refractive index distribution using digital holographic interferometry based on total internal reflection.

    PubMed

    Zhang, Jiwei; Di, Jianglei; Li, Ying; Xi, Teli; Zhao, Jianlin

    2015-10-19

    We present a method for dynamically measuring the refractive index distribution in a large range based on the combination of digital holographic interferometry and total internal reflection. A series of holograms, carrying the index information of mixed liquids adhered on a total reflection prism surface, are recorded with CCD during the diffusion process. Phase shift differences of the reflected light are reconstructed exploiting the principle of double-exposure holographic interferometry. According to the relationship between the reflection phase shift difference and the liquid index, two dimensional index distributions can be directly figured out, assuming that the index of air near the prism surface is constant. The proposed method can also be applied to measure the index of solid media and monitor the index variation during some chemical reaction processes. PMID:26480394

  4. Studies on breast tumor tissues with ATR-FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Yu, Ge; Xu, Jialin; Niu, Yun; Zhang, Cunzhou; Zhang, Chunping

    2005-01-01

    The original and deconvoluted spectra of Attenuated Total Reflection (ATR) FTIR have been determined for both benign and malignant tumor tissues samples and the spectral differences have been investigated between the two types of samples. In comparison with the benign samples, the characteristic changes of malignant ones mainly involve: The prominent bands 1652 and 1645cm-1 due to the proteins in the ?-helical and the unordered-random-coils substructures become stronger compared to those in the ?-sheet and the turns substructures, suggesting that the former type of proteins increase in content in contrast to the later. The phospodiester band 1083 cm-1 of the nucleic acids becomes strongest on cancer tissues spectra and its area ratio to the amide II band 1548cm-1 rises greatly, indicating that the DNA content rises remarkably. The collagen proteins reduce in content while phosphorylated ones rise, and some hydrogen bonding is nearly broken in amino acid residue C-O (H) groups. The glycogen content decreases, and the CH2 content is higher than CH3 one. These results suggest that ATR-FTIR spectroscopy has the potential to become a powerful tool for biochemical studies and in vivo diagnosis of human breast cancers.

  5. Total-reflection active-mirror laser with cryogenic Yb:YAG ceramics.

    PubMed

    Furuse, Hiroaki; Kawanaka, Junji; Takeshita, Kenji; Miyanaga, Noriaki; Saiki, Taku; Imasaki, Kazuo; Fujita, Masayuki; Ishii, Shinya

    2009-11-01

    An efficient high-power laser operation has been demonstrated by using a cryogenic Yb:YAG composite ceramic with a total-reflection active-mirror arrangement. The composite ceramic, which had no high-reflection coating and was cooled with liquid nitrogen directly, showed four-level operation even at 67 kW/cm(3) of high pump density. A 273 W cw output power was obtained with 65% optical efficiency and 72% slope efficiency. PMID:19881620

  6. 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.

  7. Phylogeny of cultivated and wild wheat species using ATR-FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Demir, Pinar; Onde, Sertac; Severcan, Feride

    2015-01-01

    Within the last decade, an increasing amount of genetic data has been used to clarify the problems inherent in wheat taxonomy. The techniques for obtaining and analyzing these data are not only cumbersome, but also expensive and technically demanding. In the present study, we introduce infrared spectroscopy as a method for a sensitive, rapid and low cost phylogenetic analysis tool for wheat seed samples. For this purpose, 12 Triticum and Aegilops species were studied by Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy. Hierarchical cluster analysis and principal component analysis clearly revealed that the lignin band (1525-1505 cm-1) discriminated the species at the genus level. However, the species were clustered according to their genome commonalities when the whole spectra were used (4000-650 cm-1). The successful differentiation of Triticum and its closely related genus Aegilops clearly demonstrated the power of ATR-FTIR spectroscopy as a suitable tool for phylogenetic research.

  8. Orientation of molecular groups of fibers in nonoriented samples determined by polarized ATR-FTIR spectroscopy.

    PubMed

    Belbachir, Karima; Lecomte, Sophie; Ta, Ha-Phuong; Petibois, Cyril; Desbat, Bernard

    2011-12-01

    A method based on polarized attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is proposed for determining the infrared dichroic absorption ratio of a single fiber from a sample deposited flat on a germanium crystal without the requirement of fiber orientation. The method shows its efficiency on cellulose fibers of paper and has been applied to protein fibers (type I collagen and ?-amyloid) and polysaccharide fibers (cellulose and starch). The method gives access to the dichroic ratio of strong absorptions bands, which is not easily accessible with conventional absorption techniques. Then, the orientation of the molecular groups of organic fibers can be easily determined by polarized ATR-FTIR spectroscopy. By extension, this method will be useful to determine the molecular orientation of fibers in structured complex samples, such as biological tissues and plants. Spatially resolved information on the organization of the fiber network will be easily extracted by utilizing a focal plane array detector for imaging measurements. PMID:21964809

  9. ATR-FTIR observations of water structure in colloidal silica: implications for the hydration force mechanism.

    PubMed

    Bailey, J Ryan; McGuire, Molly M

    2007-10-23

    Attenuated total internal reflection Fourier-transform infrared spectroscopy (ATR-FTIR) was used to probe the change in water structure in silica colloids as a function of particle density. The absorption index (k) spectra were calculated from the ATR spectra using the subtractive Kramers-Kronig transform in order to avoid the effects of the density-dependent refractive index on the raw spectra and allow direct comparison of the different chemical environments. Normalized difference spectra were obtained by subtracting the k spectrum of bulk water from those of the silica colloids. At low particle densities, these difference spectra reveal the presence of a strongly hydrogen-bonded hydration layer at the surface of the colloidal particles. At higher particle densities, the hydrogen-bonding network is increasingly disrupted. The results provide direct experimental evidence of hydrogen-bond breaking as the mechanism for the hydration force, which provides the extraordinary stability of colloidal silica. PMID:17880116

  10. Phylogeny of cultivated and wild wheat species using ATR-FTIR spectroscopy.

    PubMed

    Demir, Pinar; Onde, Sertac; Severcan, Feride

    2015-01-25

    Within the last decade, an increasing amount of genetic data has been used to clarify the problems inherent in wheat taxonomy. The techniques for obtaining and analyzing these data are not only cumbersome, but also expensive and technically demanding. In the present study, we introduce infrared spectroscopy as a method for a sensitive, rapid and low cost phylogenetic analysis tool for wheat seed samples. For this purpose, 12 Triticum and Aegilops species were studied by Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy. Hierarchical cluster analysis and principal component analysis clearly revealed that the lignin band (1525-1505 cm(-1)) discriminated the species at the genus level. However, the species were clustered according to their genome commonalities when the whole spectra were used (4000-650 cm(-1)). The successful differentiation of Triticum and its closely related genus Aegilops clearly demonstrated the power of ATR-FTIR spectroscopy as a suitable tool for phylogenetic research. PMID:25145919

  11. Structure-Activity Relations In Enzymes: An Application Of IR-ATR Modulation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Fringeli, Urs P.; Ahlstrom, Peter; Vincenz, Claudius; Fringeli, Marianna

    1985-12-01

    Relations between structure and specific activity in immobilized acetylcholinesterase (ACNE) have been studied by means of pH- and Ca++-modulation technique combined with attenuated total reflection (ATR) infrared (IR) spectroscopy and enzyme activity measurement. Periodic modulation of pH and Ca++-concentration enabled a periodic on-off switching of about 40% of the total enzyme activity. It was found that about 0.5 to 1% of the amino acids were involved in this process. These 15 to 30 amino acids assumed antiparallel pleated sheet structure in the inhibited state and random and/or helical structure in the activated state.

  12. Corrosion inhibitor film formation studied by ATR-FTIR

    SciTech Connect

    Campbell, S.; Jovancicevic, V.

    1999-11-01

    The development of an inhibitor film is essential for the effective performance of a corrosion inhibitor. The use of attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR) allows the development of inhibitor films on iron oxides to be monitored. For two distinct corrosion inhibitor chemistries, oleic imidazoline and phosphate ester, the film formation and corrosion processes are monitored on Fe{sub 3}O{sub 4} in a powdered form (a model surface). Additional data following on the physical and chemical properties are obtained using XPS and SEM techniques, which allows for a more complete characterization of the model inhibitor/oxide system. By the proper choice of system and measurement techniques, the complex phenomenon of corrosion inhibition may be analyzed directly.

  13. Measurement of the Longitudinal Shift of Radiation at Total Internal Reflection by Microwave Techniques

    ERIC Educational Resources Information Center

    Akylas, Victor; And Others

    1976-01-01

    Describes a method to experimentally determine the longitudinal shift of a microwave beam at total internal reflection. Suggests that the activity be incorporated into an undergraduate laboratory program due to its ease in set-up and clarity of results. (CP)

  14. Total Reflection X-ray Microscopy in a SEM: 1. Principle and performance

    NASA Astrophysics Data System (ADS)

    Jibaoui, H.; Erre, D.; Cazaux, J.

    2000-05-01

    Total Reflection X-ray Microscopy permits to obtain topographic images of surfaces and interfaces. The principle and performance of this new microscopy are described and discussed. The experimental arrangement is installed inside a conventional SEM equipped with a CCD camera and with a special mechanical set-up. Some images illustrating the performance are also shown.

  15. Total Reflection X-Ray Microscopy in a SEM: 2. Application to surfaces and interfaces

    NASA Astrophysics Data System (ADS)

    Jibaoui, H.; Erre, D.; Cazaux, J.

    2000-05-01

    Some applications of Total Reflection X-Ray Microscopy (TRXRM) are given. It is demonstrated that this new imaging technique permits to acquire rapidly (a few seconds) digital images related to the topography of the irradiated surfaces. An important illustration is the direct imaging of slightly buried solid/solid interfaces.

  16. Reconstruction of the net emission distribution from the total radiance distribution on a reflecting surface.

    PubMed

    Ruyten, W

    2001-01-01

    The problem is considered of reconstructing, from a measurement of the total radiance distribution on an emitting surface, the radiance distribution that would be observed in the absence of reflected radiation. An explicit solution of the implied inverse problem is derived for the case in which the reflective properties of the surface are given in terms of a bidirectional reflection distribution function. Also considered are the limiting cases of diffuse and specular reflection. Practical considerations are discussed for application of the theory to the nonintrusive and remote measurement of temperatures and pressures on concave surfaces, either by traditional radiometry or by the use of thermographic phosphors and temperature- and pressure-sensitive paints. PMID:11152000

  17. Hard x-ray nanofocusing using total-reflection zone plates

    NASA Astrophysics Data System (ADS)

    Takano, Hidekazu; Tsuji, Takuya; Matsumura, Atsuyuki; Sakka, Kenji; Tsusaka, Yoshiyuki; Kagoshima, Yasushi

    2016-01-01

    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.

  18. Multivariate Analysis of Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopic Data to Confirm Phase Partitioning in Methacrylate-Based Dentin Adhesive

    PubMed Central

    Ye, Qiang; Parthasarathy, Ranganathan; Abedin, Farhana; Laurence, Jennifer S.; Misra, Anil; Spencer, Paulette

    2014-01-01

    Water is ubiquitous in the mouths of healthy individuals and is a major interfering factor in the development of a durable seal between the tooth and composite restoration. Water leads to the formation of a variety of defects in dentin adhesives; these defects undermine the tooth-composite bond. Our group recently analyzed phase partitioning of dentin adhesives using high-performance liquid chromatography (HPLC). The concentration measurements provided by HPLC offered a more thorough representation of current adhesive performance and elucidated directions to be taken for further improvement. The sample preparation and instrument analysis using HPLC are, however, time-consuming and labor-intensive. The objective of this work was to develop a methodology for rapid, reliable, and accurate quantitative analysis of near-equilibrium phase partitioning in adhesives exposed to conditions simulating the wet oral environment. Analysis by Fourier transform infrared (FT-IR) spectroscopy in combination with multivariate statistical methods, including partial least squares (PLS) regression and principal component regression (PCR), were used for multivariate calibration to quantify the compositions in separated phases. Excellent predictions were achieved when either the hydrophobic-rich phase or the hydrophilic-rich phase mixtures were analyzed. These results indicate that FT-IR spectroscopy has excellent potential as a rapid method of detection and quantification of dentin adhesives that experience phase separation under conditions that simulate the wet oral environment. PMID:24359662

  19. Real-time feedback control using online attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy for continuous flow optimization and process knowledge.

    PubMed

    Skilton, Ryan A; Parrott, Andrew J; George, Michael W; Poliakoff, Martyn; Bourne, Richard A

    2013-10-01

    The use of automated continuous flow reactors is described, with real-time online Fourier transform infrared spectroscopy (FT-IR) analysis to enable rapid optimization of reaction yield using a self-optimizing feedback algorithm. This technique has been applied to the solvent-free methylation of 1-pentanol with dimethyl carbonate using a ?-alumina catalyst. Calibration of the FT-IR signal was performed using gas chromatography to enable quantification of yield over a wide variety of flow rates and temperatures. The use of FT-IR as a real-time analytical technique resulted in an order of magnitude reduction in the time and materials required compared to previous studies. This permitted a wide exploration of the parameter space to provide process understanding and validation of the optimization algorithms. PMID:24067568

  20. Super hydrophobic surface of polytetrafluoroethylene fabricated by picosecond laser and phenomenon of total internal reflection underwater

    NASA Astrophysics Data System (ADS)

    Jiang, Yijian; Cao, Wenshen; Zhao, Yan; Wu, Yan; Ji, Lingfei

    2015-03-01

    A groove-shaped array with average 25 ?m interval, 25 ?m wall thickness, 75 ?m depth and a columnar array with average 30 ?m side length, 25 ?m interval, 43 ?m depth are processed by 1064 nm picosecond laser on polytetrafluoroethylene (PTFE) surface at room temperature. The water contact angle of modified PTFE surface can reach 167, which show super hydrophobic surface of PTFE is prepared. It is observed super hydrophobic surface reflects metal luster underwater through the glassware when super hydrophobic PTFE entirely immerses in pure water. The experiment conducts super hydrophobic surface will enhance intensity of reflection of visible light underwater, which is due to total internal reflection of super hydrophobic surface und erwater.

  1. 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.

  2. Optical fiber biosensor based on multiple total internal reflections in heterodyne interferometry

    NASA Astrophysics Data System (ADS)

    Wang, Shinn-Fwu; Chiu, Jyh-Shyan; Wang, Ming-Jen

    2007-07-01

    In this paper, an optical fiber biosensor based on multiple total internal reflections in heterodyne interferometry is proposed. The sensor is made of a long U-shaped multimode optical fiber which cladding is removed from the sensing portion of the fiber. With the optical fiber biosensor the phase shift difference due to the multiple total internal reflections (MTIR) effect between the P and S-polarizations is measured by using heterodyne interferometry with the optical fiber biosensor. Substituting the phase shift difference into Fresnel's equations, the refractive index for the tested medium can be calculated. The resolution of the sensor can reach 1.5810 -6 refractive index unit (RIU). The optical fiber biosensor could be valuable for chemical, biological and biochemical sensing. It has some merits, such as, high resolution and stability, small size and real-time measurement.

  3. U-shaped optical fiber sensor based on multiple total internal reflections in heterodyne interferometry

    NASA Astrophysics Data System (ADS)

    Wang, Shinn-Fwu

    2009-10-01

    In this paper, an optical fiber sensor based on multiple total internal reflections (MTIRs) in heterodyne interferometry is proposed. With the optical fiber sensor the phase shift difference due to the multiple total internal reflections effect between the p- and s-polarizations is measured by using heterodyne interferometry. Substituting the phase shift difference into Fresnel's equations, the refractive index for the tested medium can be calculated. The resolution of the sensor can reach 1.610 -6 refractive index unit (RIU). The optical fiber sensor could be valuable for chemical, biological and biochemical sensing. It has some merits, such as, high resolution and stability, high sensitivity, high resolution and real-time measurement.

  4. Polar magneto-optical effects in magnetoplasmonic thin films illuminated by attenuated total reflection

    NASA Astrophysics Data System (ADS)

    Yan, Cunji; Han, Li; Yang, Jinbo; Gu, Wenqi

    2014-09-01

    We investigate the polar magneto-optical Kerr effect as a function of the angle of incidence in Co/Au thin films under attenuated total reflection conditions. An experimental method is proposed to measure the intrinsic polar magneto-optical Kerr rotation of the magnetoplasmonic films while considering the influence of the glass Faraday magneto-optical effect. The experimental results demonstrate that the Kerr rotations of these films are greatly affected by a number of factors including the angle of incidence, the linear polarization of the incident light, and the film thickness. The results suggest that the polar magneto-optical activity is affected by the evanescent fields decaying inside the films; these fields arise not only from attenuated total reflection at the glass/metal interface but also from the surface plasmon polaritons at the metal/air interface. A close relationship between the magneto-optical activity and the electromagnetic field distribution within the magnetoplasmonic films is clearly revealed.

  5. 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.

  6. 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.

  7. NOTE: Refractive index measurement for biomaterial samples by total internal reflection

    NASA Astrophysics Data System (ADS)

    Jin, Y. L.; Chen, J. Y.; Xu, L.; Wang, P. N.

    2006-10-01

    The refractive index of biological tissue is a fundamental parameter in applications of optical diagnosis and laser treatments. In the present work, the refractive indices and thermo-optic coefficients of some basic biomaterials, such as blood plasma, haemoglobin solution and lipid membrane, were studied by the method of total internal reflection at the wavelengths of 532 and 632.8 nm that are the most frequently used laser wavelengths in the biomedical field. The effects of the sample concentration and the temperature on refractive index were measured, and empirical relationships were summarized, accompanied by a theoretical explanation based on molecular polarization theory. The results provide some fundamental data for the refractive indices of these biomaterials under variant conditions, and also demonstrate that the total internal reflection method is a feasible and reliable way to measure the refractive indices of biological samples.

  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. Total-Internal-Reflection-Fluorescence Microscopy for the Study of Nanobubble Dynamics

    NASA Astrophysics Data System (ADS)

    Chan, Chon U.; Ohl, Claus-Dieter

    2012-10-01

    Nanobubbles can be observed with optical microscopy using the total-internal-reflection-fluorescence excitation. We report on total-internal-reflection-fluorescence visualization using rhodamine 6G at 5?M concentration which results in strongly contrasting pictures. The preferential absorption and the high spatial resolution allow us to detect nanobubbles with diameters of 230 nm and above. We resolve the nucleation dynamics during the water-ethanol-water exchange: within 4 min after exchange the bubbles nucleate and form a stable population. Additionally, we demonstrate that tracer particles near to the nanobubbles are following Brownian motion: the remaining drift flow is weaker than a few micrometers per second at a distance of 400 nm from the nanobubbles center.

  10. ATR-FTIR spectroscopy and chemometrics: An interesting tool to discriminate and characterize counterfeit medicines.

    PubMed

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

    2015-08-10

    Counterfeit medicines pose a huge threat to public health worldwide. High amounts of counterfeit pharmaceuticals enter the European market and therefore detection of these products is essential. Attenuated Total Reflection Fourier-Transform infrared spectroscopy (ATR-FTIR) might be useful for the screening of counterfeit medicines since it is easy to use and little sample preparation is required. Furthermore, this approach might be helpful to customs to obtain a first evaluation of suspected samples. This study proposes a combination of ATR-FTIR and chemometrics to discriminate and classify counterfeit medicines. A sample set, containing 209 samples in total, was analyzed using ATR-FTIR and the obtained spectra were used as fingerprints in the chemometric data-analysis which included Principal Component Analysis (PCA), k-Nearest Neighbours (k-NN), Classification and Regression Trees (CART) and Soft Independent Modelling of Class Analogy (SIMCA). First it was verified whether the mentioned techniques are capable to distinguish samples containing different active pharmaceutical ingredients (APIs). PCA showed a clear tendency of discrimination based on the API present; k-NN, CART and SIMCA were capable to create suitable prediction models based on the presence of different APIs. However k-NN performs the least while SIMCA performs the best. Secondly, it was tested whether these three models could be expanded to discriminate between genuine and counterfeit samples as well. k-NN was not able to make the desired discrimination and therefore it was not useful. CART performed better but also this model was less suited. SIMCA, on the other hand, resulted in a model with a 100% correct discrimination between genuine and counterfeit drugs. This study shows that chemometric analysis of ATR-FTIR fingerprints is a valuable tool to discriminate genuine from counterfeit samples and to classify counterfeit medicines. PMID:25476739

  11. TOTAL INTERNAL REFLECTION WITH FLUORESCENCE CORRELATION SPECTROSCOPY: APPLICATIONS TO SUBSTRATE-SUPPORTED PLANAR MEMBRANES

    PubMed Central

    Thompson, Nancy L.; Wang, Xiang; Navaratnarajah, Punya

    2009-01-01

    In this review paper, the conceptual basis and experimental design of total internal reflection with fluorescence correlation spectroscopy (TIR-FCS) is described. The few applications to date of TIR-FCS to supported membranes are discussed, in addition to a variety of applications not directly involving supported membranes. Methods related, but not technically equivalent, to TIR-FCS are also summarized. Future directions for TIR-FCS are outlined. PMID:19269331

  12. 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.

  13. 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. PMID:15072036

  14. Quantitative measurement of permeabilization of living cells by terahertz attenuated total reflection

    NASA Astrophysics Data System (ADS)

    Grognot, Marianne; Gallot, Guilhem

    2015-09-01

    Using Attenuated Total Reflection imaging technique in the terahertz domain, we demonstrate non-invasive, non-staining real time measurements of cytoplasm leakage during permeabilization of epithelial cells by saponin. The terahertz signal is mostly sensitive to the intracellular protein concentration in the cells, in a very good agreement with standard bicinchoninic acid protein measurements. It opens the way to in situ real time dynamics of protein content and permeabilization in live cells.

  15. 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-Fie?ko, 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.

  16. Application of total internal reflection microscopy for laser damage studies on fused silica

    NASA Astrophysics Data System (ADS)

    Sheehan, Lynn M.; Kozlowski, Mark R.; Camp, David W.

    1998-04-01

    Damage studies show that the majority of damage on UV grade fused silica initiates at the front or rear surface. The grinding and polishing processes used to produce the optical surfaces of transparent optics play a key role in the development of defects which can ultimately initiate damage. These defects can be on or breaking through the surface or can be sub-surface and surface defects in transparent materials. Images taken which compare both total internal reflection microscopy and atomic force microscopy show that the observed defects can be less than one micron in size. Total internal reflection microscopy has the added benefit of being able to observe large areas with sub-micron detection. Both off-line and in- situ systems have been applied in the Lawrence Livermore National Laboratory's damage laboratory in order to understand defects in the surface and subsurface of polished fused silica. There is a preliminary indication that TIRM quality can be related to the damage resistance. The in-situ microscope is coupled into a 355 nm, 7.5 ns, 10 Hz Nd:YAG laser system in order to study damage occurring at localized scatter sites revealed with the total internal reflection microscopy method. The tests indicate damage initiating at observed artifacts which have many different morphologies and damage behaviors. Some of the scatter sites and damage morphologies revealed have been related back to the finishing process.

  17. FTIR-ATR spectroscopy applied to quality control of grape-derived spirits.

    PubMed

    Anjos, Ofélia; Santos, António J A; Estevinho, Letícia M; Caldeira, Ilda

    2016-08-15

    The Fourier transform infrared (FTIR) spectroscopic method with attenuated total reflectance (ATR) was used for predicting the alcoholic strength, the methanol, acetaldehyde and fusel alcohols content of grape-derived spirits. FTIR-ATR spectrum in the mid-IR region (4000-400cm(-1)) was used for the quantitative estimation by applying partial least square (PLS) regression models and the results were correlated with those obtained from reference methods. In the developed method, a cross-validation with 50% of the samples was used for PLS analysis along with a validation test set with 50% of the remaining samples. Good correlation models with a great accuracy were obtained for methanol (r(2)=99.4; RPD=12.8), alcoholic strength (r(2)=97.2; RPD=6.0), acetaldehyde (r(2)=98.2; RPD=7.5) and fusel alcohols (r(2) from 97.4 to 94.1; RPD from 6.2 to 4.1). These results corroborate the hypothesis that FTIR-ATR is a useful technique for the quality control of grape-derived spirits, whose practical application may improve the efficiency and quickness of the current laboratory analysis. PMID:27006210

  18. 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.

  19. 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%. PMID:25571103

  20. Total internal reflection optical switch using the reverse breakdown of a pn junction in silicon.

    PubMed

    Kim, Jong-Hun; Park, Hyo-Hoon

    2015-11-01

    We demonstrate a new type of silicon total-internal-reflection optical switch with a simple pn junction functioning both as a reflector and a heater. The reflector is placed between asymmetrically y-branched multimode waveguides with an inclination angle corresponding to half of the branch angle. When the reflector is at rest, incident light is reflected in accordance to the refractive index difference due to the plasma dispersion effect of the pre-doped carriers. Switching to the transmission state is attained under a reverse breakdown of the pn junction by the thermo-optic effect which smears the refractive index difference. From this switching scheme, we confirmed the switching operation with a shallow total-internal-reflection region of 1 ?m width. At a 6 branch angle, an extinction ratio of 12 dB and an insertion loss of -4.2??dB are achieved along with a thermal heating power of 151.5 mW. PMID:26512468

  1. Development of thin-film total-reflection mirrors for the XUV FEL

    NASA Astrophysics Data System (ADS)

    Jacobi, Sandra; Wiesmann, Joerg; Steeg, Barbara; Feldhaus, Josef; Michaelsen, Carsten

    2001-12-01

    A free electron laser for the XUV spectral range is currently under test at the TESLA Test Facility at DESY. High gain has been demonstrated below 100nm wavelength, and it is expected that the FEL will provide intense, sub-picosecond radiation pulses with photon energies up to 200eV. Thin film optical elements required for this facility are currently being developed by the X-ray optics group of the GKSS research center near Hamburg. Sputter-deposited coatings have been prepared for the use as total reflection X-ray mirrors for FEL beam optics. Coatings of low Z elements with the lowest possible absorption and high reflectivity have been investigated. Silicon substrates have been coated with carbon using different deposition conditions. The films were investigated using the soft X-ray reflectometer at the HASYLAB beamline G1. The measurements show that the reflectivity of the films is typically 90% at energies below 200eV and a grazing incidence angle of 4 degrees. The optical constants of these coatings obtained from the reflectivity measurements and are in agreement with tabulated values. The deposition parameters have been optimized resulting in argon contamination free films with near-theoretical performance. Preliminary investigations concerning the heat resistance of the films were also carried out.

  2. Dye bonding to TiO2: in situ attenuated total reflection infrared spectroscopy study, simulations, and correlation with dye-sensitized solar cell characteristics.

    PubMed

    Vlker, Barbara; Wlzl, Florian; Brgi, Thomas; Lingenfelser, Dominic

    2012-08-01

    Processing dye-sensitized solar cells gains more and more importance as interest in industrial applications grows daily. For large-scale processing and optimizing manufacturing in terms of environmental acceptability as well as time and material saving, a detailed knowledge of certain process steps is crucial. In this paper we concentrate on the sensitizing step of production, i.e., the anchoring of the dye molecules onto the TiO(2) semiconductor. A vacuum-tight attentuated total reflection infrared (ATR-IR) flow-through cell was developed, thus allowing measurements using a vacuum spectrometer to monitor infiltration of dye molecules into the porous TiO(2) film in situ at high sensitivity. In particular, the influence of the anchor and backbone of perylene dye molecules as well as the influence of solvents on the adsorption process was investigated. The experiments clearly show that an anhydride group reacts much slower than an acid group. A significantly lower amount of anhydride dye can be adsorbed on the films. Ex situ transmission experiments furthermore indicate that the availability of OH groups on the TiO(2) surface may limit dye adsorption. Also the backbone and base frame of the dye can influence the adsorption time drastically. Electrical cell characteristics correlate with the amount of adsorbed dye molecules determined by in situ ATR-IR measurements. The latter is also sensitive toward the diffusion of the dye through the porous layer. To gain a deeper understanding of the interplay between diffusion and adsorption, simulations were performed that allowed us to extract diffusion and adsorption constants. Again it was demonstrated that the anchoring group has a strong effect on the adsorption rate. The influence of the solvent was also studied, and it was found that both adsorption and desorption are affected by the solvent. Protic polar solvents are able to remove bound dye molecules, which is a possible pathway of cell degradation. Most importantly, the analysis shows the potential of this approach for the evaluation of molecules or additives concerning their characteristics important for cell processing. PMID:22775480

  3. Total internal reflection imaging of microorganism adhesion using an oil immersion objective.

    PubMed

    Velinov, Tzvetan; Asenovska, Yana; Marinkova, Dessislava; Yotova, Lyubov; Stoitsova, Stoyanka; Bivolarska, Maria; Stavitskaya, Lyuba

    2011-11-01

    In this paper, we report the results of total internal reflection microscopy investigations of the interaction of two types of microorganisms: Saccharomyces cerevisiae and Escherichia coli with substrates. It is shown that with this method qualitative and quantitative information about cells-substrate interaction can be obtained. One can easily make a difference between attached and non-attached as well as between dead and alive cells, and more generally can follow the dynamics of the process of cells' attachment to substrates. Quantitative information about the cell size and cell-substrate distance is obtained by using a model in which yeast cells and bacteria are approximated by ellipsoids, and multiple reflections of the evanescent waves between the cells and the substrate are neglected. PMID:21820880

  4. Note: Portable total reflection X-ray fluorescence spectrometer with small vacuum chamber.

    PubMed

    Kunimura, Shinsuke; Kudo, Shunpei; Nagai, Hiroki; Nakajima, Yoshihide; Ohmori, Hitoshi

    2013-04-01

    To improve the detection limits of a portable total reflection X-ray fluorescence (TXRF) spectrometer using white X-rays (i.e., both characteristic X-rays and continuum X-rays) from a 5 W X-ray tube, the measurement was performed in vacuum. The TXRF spectrum measured in vacuum was compared with that measured in air. The spectral background was significantly reduced when the scattering of the incident X-rays from air was reduced using a vacuum pump, leading to improvement in the detection limit. A detection limit of 8 pg was achieved for Cr when measuring in vacuum. PMID:23635242

  5. Environmental trace-element analysis using a benchtop total reflection X-ray fluorescence spectrometer.

    PubMed

    Stosnach, Hagen

    2005-07-01

    Total reflection X-ray fluorescence (TXRF) analysis is an established technique for trace-element analysis in various types of samples. Though expensive large-scale systems restricted the applications in the past, in this study the capability of a benchtop system for trace elemental analysis is reported. The suitability of this system for the mobile on-site analysis of heavy metal contaminated soils and sediments is reported as well as the possibilities and restrictions of TXRF for additional applications, including trace-element analysis of water, glass and biological samples. PMID:16038513

  6. Optimization of a total internal reflection lens by using a hybrid Taguchi-simulated annealing algorithm

    NASA Astrophysics Data System (ADS)

    Chao, Shih-Min; Whang, Allen Jong-Woei; Chou, Chun-Han; Su, Wei-Shao; Hsieh, Tsung-Heng

    2014-03-01

    In this paper, we propose a new method for optimization of a total internal reflection (TIR) lens by using a hybrid Taguchi-simulated annealing algorithm. The conventional simulated annealing (SA) algorithm is a method for solving global optimization problems and has also been used in non-imaging systems in recent years. However, the success of SA depends heavily on the annealing schedule and initial parameter setting. In this study, we successfully incorporated the Taguchi method into the SA algorithm. The new hybrid Taguchi-simulated annealing algorithm provides more precise search results and has lower initial parameter dependence.

  7. 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.

  8. 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.

  9. 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.

  10. Trace element determination in drugs by total-reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Wagner, M.; Rostam-Khani, P.; Wittershagen, A.; Rittmeyer, Claudia; Kolbesen, B. O.; Hoffmann, H.

    1997-07-01

    The capability of total-reflection X-ray fluorescence spectrometry (TXRF) for the determination of trace elements in drugs is described. Various samples of lecithin, insulin, procaine and tryptophan of different origin were investigated. The element concentrations provide element fingerprints which offer the possibility to discriminate between different batches of the analysed substances originating from different production or purification processes. TXRF facilitates the characterization of such samples without extensive pre-treatment, and provides fast multi-element determination of elements with atomic numbers 14< Z<92 based on matrix-independent quantification by means of an internal standard.

  11. 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; Fernndez-Ruiz, Ramn; 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.

  12. Study of the interaction between HSA and oligo-DNA using total internal reflection ellipsometry

    NASA Astrophysics Data System (ADS)

    Jung, Y. W.; Byun, J. S.; Kim, Y. D.; Hemzal, D.; Humliček, J.

    2012-04-01

    Techniques of quantitative analysis are very important for studies of the interactions between bio-molecules in the field of biotechnology and drug development. The total internal reflection ellipsometry system (TIRE) is an attractive label-free procedure for the quantitative analysis of biomolecules because it combines the analytic ability of ellipsometry and the high surface sensitivity of surface plasmon resonance. In this work, we have used TIRE to study the optical properties of an aquatic monolayer of human serum albumin (HSA) and oligo-DNA. Also, we have monitored the adsorption and the interaction processes of protein layers.

  13. 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.

  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. 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. PMID:26479648

  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. PMID:19956284

  17. 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.

  18. Frustrated total internal reflection and critical coupling in a thick plasmonic grating with narrow slits

    NASA Astrophysics Data System (ADS)

    Mattiucci, N.; D'Aguanno, G.; Bloemer, M. J.; Al, A.

    2014-06-01

    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. 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.

  20. 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, Grard; 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. PMID:16004054

  1. 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 ? 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. PMID:25913607

  2. 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. PMID:26275025

  3. ATR-FTIR spectroscopic studies on density changes of fused silica induced by localized CO2 laser treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Chuan-Chao; Zhang, Li-Juan; Liao, Wei; Yan, Zhong-Hua; Chen, Jing; Jiang, Yi-Lan; Wang, Hai-Jun; Luan, Xiao-Yu; Ye, Ya-Yun; Zheng, Wan-Guo; Yuan, Xiao-Dong

    2015-02-01

    The surface density changes of the central region of the sites treated by using the CO2 laser-based non-evaporative damage mitigation for fused silica are investigated by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The ATR-FTIR peak shifts of the treated sites of fused silica are monitored to determine the changes of the corresponding density. For the quenching treated sites, the surface density is increased by (0.24 0.01)% compared with the initial density but the laser annealing by the exposure of a power ramp down after damage mitigation effectively suppresses the structural changes of treated sites, which could reduce the increase of the corresponding density to (0.08 0.01)%. The results provide sufficient evidence that the laser annealing by a power ramp down after damage mitigation has a positive effect on the control of the structural change induced by CO2 laser-based damage mitigation.

  4. Total Reflection X-ray Fluorescence attachment module modified for analysis in vacuum

    NASA Astrophysics Data System (ADS)

    Wobrauschek, P.; Streli, C.; Kregsamer, P.; Meirer, F.; Jokubonis, C.; Markowicz, A.; Wegrzynek, D.; Chinea-Cano, E.

    2008-12-01

    Based on the design of the low cost Total Reflection X-Ray Fluorescence attachment module available since 1986 from Atominstitut (WOBRAUSCHEK-module) which can be attached to existing X-ray equipment, a new version was developed which allows the analysis of samples in vacuum. This design was in particular possible as the Peltier cooled light weight Silicon Drift Detector is following all adjustment procedures for total reflection as angle rotation and linear motion. The detector is mounted through a vacuum feed and O-ring tightening to the small vacuum chamber. The standard 30 mm round quartz, Si-wafer or Plexiglas reflectors are used to carry the samples. The reflectors are placed on the reference plane with the dried sample down looking facing in about 0.5 mm distance the up looking detector window. The reflectors are resting on 3 steel balls defining precisely the reference plane for the adjustment procedure. As the rotation axis of the module is in the plane of the reflector surface, angle dependent experiments can be made to distinguish between film and particulate type contamination of samples. Operating with a Mo anode at 50 kV and 40 mA with a closely attached multilayer monochromator and using a 10 mm 2 KETEK silicon drift detector with 8 ?m Be window, a sensitivity of 70 cps/ng for Rb was measured and detection limits of 2 pg were obtained.

  5. Dielectric totally internally reflecting concentrator structure for vertical bifacial photovoltaic receivers

    NASA Astrophysics Data System (ADS)

    Thomsen, Elizabeth; Ratcliff, Thomas; Stocks, Matthew; Blakers, Andrew W.

    2015-08-01

    A new dielectric totally internally reflecting concentrator (DTIRC) design has been developed for use with bifacial photovoltaic cells. The structure incorporates the bifacial cell standing vertically at the base of the structure, immersed in dielectric. DTIRC structures with single-sided photovoltaic receivers, like CPC structures, are designed using the paths of the edge rays to calculate the sidewalls. If these rays successfully hit the receiver then all rays at lower angles will also hit the receiver. In a vertical DTIRC structure, it is not just the edge rays that need to be taken into account in designing the structure. Around the bifacial receiver, rays at normal and close to normal incidence are the hardest to totally internally reflect onto the receiver. Once outside the area closest to the receiver, a modification of the maximum concentration method is used to design the remainder of the sidewalls. Ray tracing has been performed to confirm that the vertical DTIRC structure concentrates light as expected. The structure gives a lower concentration than a CPC with vertical bifacial receiver, however it is also a shorter structure with more uniform flux distribution over the receiver (leading to lower losses in the photovoltaic receiver).

  6. Low-temperature, low-cost growth of robust ATR GeO2 hollow fibers based on copper capillary tubes for transmission of CO2 laser light

    NASA Astrophysics Data System (ADS)

    Jing, Chengbin; Bai, Wei; Hu, Zhigao; Yang, Pingxiong; Liu, Aiyun; Lin, Fangtin; Shi, Yiwei; Chu, Junhao

    2014-02-01

    Attenuated total reflectance (ATR) infrared hollow waveguide attracts particular interest since it has both advantages of a hollow fiber and a light guiding mechanism similar to that of solid-core fibers. Presently, ATR hollow waveguides are mainly structured with single-crystal sapphire or glassy materials. These waveguides are somewhat brittle. More robust ATR hollow fibers are required in many military and domestic applications. In this work, ATR GeO2 hollow waveguides were prepared based on a copper capillary tube for transmitting CO2 laser light. The inner wall of the copper structural tube was polished using a high-pressure pulsed nanofluid technique. A hexagonal crystalline GeO2 reflective layer with sufficient thickness (>4 μm) was grown on the inner tube wall via a simple liquid phase deposition process at room temperature. The GeO2 coated copper hollow fiber exhibits a low-loss band within 10-11.5 μm. It can still be bent since the hollow-core size (1.4 mm) and the wall thickness (50 μm) are not too large. The transmissions of CO2 laser light are 91% and 43% under a straight condition and a 90° bend with a 30-cm radius condition, respectively. The waveguide displays high heat-resisting properties due to high thermal conductivity of the copper substrate tube and a high melting point (1115°C) of the GeO2 reflective layer. This work opens a door for low-temperature, low-cost growth of long ATR GeO2 infrared hollow fibers based on various substrate tubes, even including plastic capillary tubes.

  7. Characterization of amorphous carbon films as total-reflection mirrors for XUV free-electron lasers

    NASA Astrophysics Data System (ADS)

    Jacobi, Sandra; Steeg, Barbara; Wiesmann, Jorg; Stormer, Michael; Feldhaus, Josef; Bormann, R.'diger; Michaelsen, Carsten

    2002-12-01

    As part of the TESLA (TeV-Energy Superconducting Linear Accelerator) project a free electron laser (FEL) in the XUV (Extreme Ultra-Violet, (6-200 eV)) and X-ray (0.5-15 keV) range is being developed at DESY (Deutsches Elektronen Synchrotron, Hamburg). At the TESLA Test Facility (TTF) a prototype FEL has recently demonstrated maximum light amplification in the range of 80 nm to 120 nm. It is expected that the FEL will provide intense, sub-picosecond radiation pulses with photon energies up to 200 eV in the next development stage. In a joint project between DESY and GKSS, thin film optical elements with very high radiation stability, as required for FEL applications, are currently being developed. Sputter-deposited amorphous carbon coatings have been prepared for use as total reflection X-ray mirrors. The optical characterization of the mirrors has been carried out using the soft X-ray reflectometer at HASYLAB (Hamburger Synchrotronstrahlungslabor) beamline G1. The reflectivity of the carbon films at 2 deg incidence angle is close to the theoretical reflectivity of 95.6 %, demonstrating the high quality of the coatings. For comparison, layers produced by different methods (e.g. Chemical vapor deposition, Pulsed laser deposition) have been characterized as well. Annealing experiments have been performed to evaluate the thermal stability of the amorphous carbon films. Further investigations concerning the radiation stability of the X-ray mirrors have also been conducted. The mirrors were irradiated in the FELIS (Free Electron Laser-Interaction with Solids) experiment at the TTF-FEL. Microscopic investigations demonstrate that the carbon mirrors are fairly stable.

  8. 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.

  9. Imaging with total internal reflection fluorescence microscopy for the cell biologist

    PubMed Central

    Mattheyses, Alexa L.; Simon, Sanford M.; Rappoport, Joshua Z.

    2010-01-01

    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. PMID:20971701

  10. Probing Membrane Fouling via Infrared Attenuated Total Reflection Mapping Coupled with Multivariate Curve Resolution.

    PubMed

    Chen, Wei; Liu, Xiao-Yang; Huang, Bao-Cheng; Wang, Long-Fei; Yu, Han-Qing; Mizaikoff, Boris

    2016-02-01

    Understanding membrane fouling induced by dissolved organic matter (DOM) is of primary importance for developing effective fouling control and prevention strategies. In this work, we combine multivariate curve resolution-alternating least squares analysis with infrared attenuated total reflection mapping to explore the fouling process of microfiltration and ultrafiltration membranes caused by two typical DOMs, humic acid (HA) and bovine serum albumin (BSA). The spectral contributions of different foulants and the membrane substrate were successfully discriminated, thereby enabling the diagnosis of fouling origins. Membrane fouling caused by HA is more severe than that by BSA. Three periods, the initial adsorption stage, the equilibrium stage, and the accumulation stage, were observed for the HA-induced fouling process. The integrated approach presented herein elegantly demonstrates the spatial and temporal characterization of membrane fouling processes, along with relative concentrations of the involved species, and suggests a promising perspective for understanding the interaction mechanisms between foulant species and membranes at the molecular level. PMID:26639164

  11. 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.

  12. Electrostatic Interactions of Fluorescent Molecules with Dielectric Interfaces Studied by Total Internal Reflection Fluorescence Correlation Spectroscopy

    PubMed Central

    Blom, Hans; Hassler, Kai; Chmyrov, Andriy; Widengren, Jerker

    2010-01-01

    Electrostatic interactions between dielectric surfaces and different fluorophores used in ultrasensitive fluorescence microscopy are investigated using objective-based Total Internal Reflection Fluorescence Correlation Spectroscopy (TIR-FCS). The interfacial dynamics of cationic rhodamine 123 and rhodamine 6G, anionic/dianionic fluorescein, zwitterionic rhodamine 110 and neutral ATTO 488 are monitored at various ionic strengths at physiological pH. As analyzed by means of the amplitude and time-evolution of the autocorrelation function, the fluorescent molecules experience electrostatic attraction or repulsion at the glass surface depending on their charges. Influences of the electrostatic interactions are also monitored through the triplet-state population and triplet relaxation time, including the amount of detected fluorescence or the count-rate-per-molecule parameter. These TIR-FCS results provide an increased understanding of how fluorophores are influenced by the microenvironment of a glass surface, and show a promising approach for characterizing electrostatic interactions at interfaces. PMID:20386645

  13. Estimation of blood alcohol concentration by horizontal attenuated total reflectance-Fourier transform infrared spectroscopy.

    PubMed

    Sharma, Kakali; Sharma, Shiba P; Lahiri, Sujit C

    2010-06-01

    Numerous methods like distillation followed by iodometric titrations, gas chromatograph (GC)-flame ionization detector, gas chromatograph-mass spectrophotometer, GC-Headspace, Breath analyzer, and biosensors including alcohol dehydrogenase (enzymatic) have been used to determine blood alcohol concentration (BAC). In the present study, horizontal attenuated total reflectance-Fourier transform infrared spectroscopy had been used to determine BAC in whole blood. The asymmetric stretching frequency of C-C-O group of ethanol in water (1,045 cm(-1)) had been used to calculate BAC using Beer's Law. A seven-point calibration curve of ethanol was drawn in the concentration range 24-790 mg dL(-1). The curve showed good linearity over the concentration range used (r(2)=0.999, standard deviation=0.0023). The method is accurate, reproducible, rapid, simple, and nondestructive in nature. PMID:20541351

  14. The mid-infrared (attenuated total reflection) spectroscopy of ethylene carbonate in water

    NASA Astrophysics Data System (ADS)

    Brooksby, Paula A.; Fawcett, W. Ronald

    2001-05-01

    Ethylene carbonate (EC) and water solution compositions ranging from pure water to 60 mass% EC have been examined using infrared (attenuated total reflection) spectroscopy. The fundamental vibrational modes of EC in the mid-infrared between 2050 and 1000 cm -1 were fitted to mixed Lorentzian-Gaussian bandshapes. The spectral data for EC bands between 1000 and 650 cm -1 are also shown but were not curve-fitted due to baseline distortions from water librational modes. The results of the band analysis have provided information regarding the molecular structure of these solutions, and the fact that the structure is also concentration dependent. The Fermi resonance coupling between the ν 2 and 2ν 7 vibrations of EC have been analysed using a standard perturbation model.

  15. Study of Spectral Modifications in Acidified Ignitable Liquids by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy.

    PubMed

    Martín-Alberca, Carlos; Ojeda, Fernando Ernesto Ortega; García-Ruiz, Carmen

    2016-03-01

    In this work, the spectral characteristics of two types of acidified gasoline and acidified diesel fuel are discussed. Neat and acidified ignitable liquids (ILs) infrared absorption spectra obtained by attenuated total reflection Fourier transform infrared spectroscopy were compared in order to identify the modifications produced by the reaction of the ILs with sulfuric acid. Several bands crucial for gasoline identification were modified, and new bands appeared over the reaction time. In the case of acidified diesel fuel, no significant modifications were observed. Additionally, the neat and acidified ILs spectra were used to perform a principal components analysis in order to confirm objectively the results. The complete discrimination among samples was successfully achieved, including the complete differentiation among gasoline types. Taking into account the results obtained in this work, it is possible to propose spectral fingerprints for the identification of non-burned acidified ILs in forensic investigations related with arson or the use of improvised incendiary devices (IIDs). PMID:26810182

  16. Polarization and far-field diffraction patterns of total internal reflection corner cubes.

    PubMed

    Murphy, Thomas W; Goodrow, Scott D

    2013-01-10

    Many corner cube prisms, or retroreflectors, employ total internal reflection (TIR) via uncoated rear surfaces. The different elliptical polarization states emerging from the six unique paths through the corner cube complicate the far-field diffraction pattern by introducing various phase delays between the six paths. In this paper, we present a computational framework to evaluate polarization through TIR corner cubes for arbitrary incidence angles and input polarization states, presenting example output for key normal-incidence conditions. We also describe a method to produce far-field diffraction patterns resulting from the polarization analysis, presenting representative images--broken into orthogonal polarizations--and characterizing key cases. Laboratory confirmation is also presented for both polarization states and far-field diffraction patterns. PMID:23314626

  17. Watch your step! A frustrated total internal reflection approach to forensic footwear imaging.

    PubMed

    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

  18. 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

  19. Analysis on the magnetic sensitivity in a total reflection prisms (TRP) ring resonator

    NASA Astrophysics Data System (ADS)

    Li, Dong; Zhao, Jianlin; Bi, Chao

    2015-07-01

    Based on the theory of transfer matrix and the condition of eigenmode self-reproduction, the model of the magnetic sensitivity in a total reflection prisms (TRP) ring laser resonator is established. Then the influences of the slight nonplanar effect on the output frequency difference and the magnetic sensitivity are analyzed theoretically and numerically. The results show that the slightly nonplanar effect will bring an additional ellipticity of the eigenmode and the environment magnetic field can produce an additional output frequency difference in a TRP ring laser resonator. It can also be found that the output frequency difference increases versus the augment of nonplanar angle and the intensity of magnetic field. These interesting results may be useful for designing and optimizing the structure of super high precision TRP ring laser gyroscopes.

  20. 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.

  1. 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. PMID:24979021

  2. Analysis of infrared attenuated total reflection spectra from thin SiO2 films on Si

    NASA Astrophysics Data System (ADS)

    Bjorkman, C. H.; Yamazaki, T.; Miyazaki, S.; Hirose, M.

    1995-01-01

    Infrared attenuated total reflection spectra from thin SiO2 films sandwiched between a Ge prism and a Si substrate were investigated. The measurements were performed in the range of Si-O-Si stretching vibrations and compared with calculated spectra using bulk values for the SiO2 dielectric function. This comparison enabled confirmation of the experimentally observed peak broadening and peak shift of the longitudinal-optical-phonon mode at approximately 1250/cm for films thicker than 30 A by using the exact expression for calculating p-polarized spectra. It is also shown that the linear approximation for vibrational spectroscopy in this frequency range is only valid for thicknesses less than 15 A.

  3. Large tunable optical absorption of CVD graphene under total internal reflection by strain engineering.

    PubMed

    Dong, Bin; Wang, Peng; Liu, Zhi-Bo; Chen, Xu-Dong; Jiang, Wen-Shuai; Xin, Wei; Xing, Fei; Tian, Jian-Guo

    2014-11-14

    We have developed a method to tune polarization-dependent optical absorption of large-scale chemical vapor deposition (CVD) graphene under total internal reflection (TIR) by strain engineering. Through control of the strain direction, the optical absorption of graphene for transverse magnetic or transverse electric waves can be separately tuned. Strain-induced modulation of the optical absorption has been theoretically expected when light is normally incident through graphene. Under TIR, however, we experimentally observed a significant increase in the strain-induced tunability of optical absorption for CVD graphene, with the modulation efficiency of optical absorption in monolayer graphene increasing by a factor of three times that for normal incidence. We conclude that the strain sensitivity of optical absorption of graphene under TIR offers significant potential for application in many areas such as ultra-thin optical devices and strain sensors. PMID:25338947

  4. Quantitative Analysis of Protein Translocations by Microfluidic Total Internal Reflection Fluorescence Flow Cytometry

    PubMed Central

    Wang, Jun; Fei, Bei; Geahlen, Robert L.

    2010-01-01

    Protein translocation, or the change in a proteins location between different subcellular compartments, is a critical process by which intracellular proteins carry out their cellular functions. Aberrant translocation events contribute to various diseases ranging from metabolic disorders to cancer. In this study, we demonstrate the use of a newly developed single-cell tool, microfluidic total internal reflection fluorescence flow cytometry (TIRF-FC), for detecting both cytosol to plasma membrane and cytosol to nucleus translocations using the tyrosine kinase Syk and the transcription factor NF-?B as models. This technique detects fluorescent molecules at the plasma membrane and in the membrane-proximal cytosol in single cells. We were able to record quantitatively changes in the fluorescence density in the evanescent field associated with these translocation processes for large cell populations with single cell resolution. We envision that TIRF-FC will provide a new approach to explore the molecular biology and clinical relevance of protein translocations. PMID:20820633

  5. 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.

  6. Development of surface sensitive DXAFS measurement method by applying Kramers-Kronig relations to total reflection spectra

    NASA Astrophysics Data System (ADS)

    Abe, Hitoshi; Niwa, Yasuhiro; Nitani, Hiroaki; Nomura, Masaharu

    2014-04-01

    Total reflection XAFS spectra are obtained combining with dispersive XAFS (DXAFS) configuration. A total reflection DXAFS spectrum of 30 nm Co layer on Si substrate was measured in 4 ms. Kramers-Kronig analysis was applied to extract XAFS signal from total reflection spectra. Spectra obtained by this method are comparable to usual XAFS spectra in terms of signal-to-noise ratios and peak positions in Fourier transformed EXAFS functions. The development of this Kramers-Kronig relations based DXAFS method is useful to study the variation of the surface state with the time resolution of millisecond.

  7. Membrane helix orientation from linear dichroism of infrared attenuated total reflection spectra.

    PubMed Central

    Bechinger, B; Ruysschaert, J M; Goormaghtigh, E

    1999-01-01

    Oriented multilamellar systems containing phospholipids and peptides have been formed on a germanium internal reflection element. Attenuated total reflection infrared spectra have been recorded and the linear dichroism of peptide amide I and amide II bands measured. Using peptides for which the orientation had been previously studied under similar experimental conditions by 15N solid-state nuclear magnetic resonance spectroscopy, important conclusions were drawn on the approach to be used to derive secondary structure orientation in a membrane from dichroic ratios. In particular, it is shown that the influence of the film thickness and refractive index on the orientation determination can be evaluated from the value of RATRiso, i.e., the dichroic ratio of a dipole oriented at the magic angle or with isotropic mobility. A series of peptides was used to test the validity of our suggestions on various helix orientations in the membrane. These include magainin 2 and hydrophobic (hPhi20) model peptides, the transmembrane segment of glycophorin (GLY), and LAH4, a designed peptide antibiotic that changes between a transmembrane and an in-plane orientation in a pH-dependent manner. PMID:9876168

  8. Total reflection X-ray fluorescence and archaeometry: Application in the Argentinean cultural heritage

    NASA Astrophysics Data System (ADS)

    Vzquez, Cristina; Albornoz, Ana; Hajduk, Adam; Elkin, Dolores; Custo, Graciela; Obrustky, Alba

    2008-12-01

    Archaeometry is an interdisciplinary research area involved in the development and use of scientific methods in order to answer questions concerned with the human history. In this way the knowledge of archaeological objects through advanced chemical and physical analyses permits a better preservation and conservation of the cultural heritage and also reveals materials and technologies used in the past. In this sense, analytical techniques play an important role in order to provide chemical information about cultural objects. Considering the non destructive characteristic of this study, analytical techniques must be adequate in order to prevent any alteration or damage and in addition to allow the conservation of their integrity. Taking into account the irreplaceable character of the archaeological and artistic materials considered in this study, analytical techniques must be adequate in order to prevent any alteration or damage and in addition to allow the conservation of their integrity. Total Reflection X-ray Fluorescence Spectrometry as a geometric variant of conventional X-ray fluorescence is a proved microanalytical technique considering the small amount of sample required for the analysis. A few micrograms are enough in order to reveal valuable information about elemental composition and in this context it is highly recommended for artwork studies. In this paper a case study is presented in which Total Reflection X-Ray Fluorescence Spectrometry has been successfully employed in the archaeometry field. Examples from Argentinean cultural heritage sites related with the determination of pigments in paintings on canvas and in rock sites as well as in underwater archaeology research are shown.

  9. 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.

  10. 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.

  11. An informative confidence metric for ATR.

    SciTech Connect

    Bow, Wallace Johnston Jr.; Richards, John Alfred; Bray, Brian Kenworthy

    2003-03-01

    Automatic or assisted target recognition (ATR) is an important application of synthetic aperture radar (SAR). Most ATR researchers have focused on the core problem of declaration-that is, detection and identification of targets of interest within a SAR image. For ATR declarations to be of maximum value to an image analyst, however, it is essential that each declaration be accompanied by a reliability estimate or confidence metric. Unfortunately, the need for a clear and informative confidence metric for ATR has generally been overlooked or ignored. We propose a framework and methodology for evaluating the confidence in an ATR system's declarations and competing target hypotheses. Our proposed confidence metric is intuitive, informative, and applicable to a broad class of ATRs. We demonstrate that seemingly similar ATRs may differ fundamentally in the ability-or inability-to identify targets with high confidence.

  12. 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 I? 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.

  13. 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 Central

    Zscherp, Christian; Schlesinger, Ramona; Tittor, Jrg; Oesterhelt, Dieter; Heberle, Joachim

    1999-01-01

    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. PMID:10318912

  14. Root discrimination of closely related crop and weed species using FT MIR-ATR spectroscopy.

    PubMed

    Meinen, Catharina; Rauber, Rolf

    2015-01-01

    Root discrimination of species is a pre-condition for studying belowground competition processes between crop and weed species. In this experiment, we tested Fourier transform mid-infrared (FT MIR)-attenuated total reflection (ATR) spectroscopy to discriminate roots of closely related crop and weed species grown in the greenhouse: maize/barnyard grass, barley/wild oat, wheat/blackgrass (Poaceae), and sugar beet/common lambsquarters (Chenopodiaceae). Fresh (moist) and dried root segments as well as ground roots were analyzed by FT MIR-ATR spectroscopy. Root absorption spectra showed species specific peak distribution and peak height. A clear separation according to species was not possible with fresh root segments. Dried root segments (including root basis, middle section, and root tip) of maize/barnyard grass and sugar beet/common lambsquarters formed completely separated species clusters. Wheat and blackgrass separated in species specific clusters when root tips were removed from cluster analysis. A clear separation of dried root segments according to species was not possible in the case of barley and wild oat. Cluster analyses of ground roots revealed a 100% separation of all tested crop and weed species combinations. Spectra grouped in Poaceae and Chenopodiaceae clusters. Within the Poaceae cluster, C3 and C4 species differed significantly in heterogeneity. Thus, root spectra reflected the degree of kinship. To quantify species proportion in root mixtures, a two- and a three-species model for species quantification in root mixtures of maize, barnyard grass, and wild oat was calculated. The models showed low standard errors of prediction (RMSEP) and high residual predictive deviation values in an external test set validation. Hence, FT MIR-ATR spectroscopy seems to be a promising tool for root research even between closely related plant species. PMID:26483799

  15. Root discrimination of closely related crop and weed species using FT MIR-ATR spectroscopy

    PubMed Central

    Meinen, Catharina; Rauber, Rolf

    2015-01-01

    Root discrimination of species is a pre-condition for studying belowground competition processes between crop and weed species. In this experiment, we tested Fourier transform mid-infrared (FT MIR)-attenuated total reflection (ATR) spectroscopy to discriminate roots of closely related crop and weed species grown in the greenhouse: maize/barnyard grass, barley/wild oat, wheat/blackgrass (Poaceae), and sugar beet/common lambsquarters (Chenopodiaceae). Fresh (moist) and dried root segments as well as ground roots were analyzed by FT MIR-ATR spectroscopy. Root absorption spectra showed species specific peak distribution and peak height. A clear separation according to species was not possible with fresh root segments. Dried root segments (including root basis, middle section, and root tip) of maize/barnyard grass and sugar beet/common lambsquarters formed completely separated species clusters. Wheat and blackgrass separated in species specific clusters when root tips were removed from cluster analysis. A clear separation of dried root segments according to species was not possible in the case of barley and wild oat. Cluster analyses of ground roots revealed a 100% separation of all tested crop and weed species combinations. Spectra grouped in Poaceae and Chenopodiaceae clusters. Within the Poaceae cluster, C3 and C4 species differed significantly in heterogeneity. Thus, root spectra reflected the degree of kinship. To quantify species proportion in root mixtures, a two- and a three-species model for species quantification in root mixtures of maize, barnyard grass, and wild oat was calculated. The models showed low standard errors of prediction (RMSEP) and high residual predictive deviation values in an external test set validation. Hence, FT MIR-ATR spectroscopy seems to be a promising tool for root research even between closely related plant species. PMID:26483799

  16. Cleaning-in-place of immunoaffinity resins monitored by in situ ATR-FTIR spectroscopy.

    PubMed

    Boulet-Audet, Maxime; Byrne, Bernadette; Kazarian, Sergei G

    2015-09-01

    In the next 10 years, the pharmaceutical industry anticipates that revenue from biotherapeutics will overtake those generated from small drug molecules. Despite effectively treating a range of chronic and life-threatening diseases, the high cost of biotherapeutics limits their use. For biotherapeutic monoclonal antibodies (mAbs), an important production cost is the affinity resin used for protein capture. Cleaning-in-place (CIP) protocols aim to optimise the lifespan of the resin by slowing binding capacity decay. Binding assays can determine resin capacity from the mobile phase, but do not reveal the underlying causes of Protein A ligand degradation. The focus needs to be on the stationary phase to examine the effect of CIP on the resin. To directly determine both the local Protein A ligand concentration and conformation on two Protein A resins, we developed a method based on attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. ATR-FTIR spectroscopic imaging revealed that applying a carefully controlled load to agarose beads produces an even and reproducible contact with the internal reflection element. This allowed detection and quantification of the binding capacity of the stationary phase. ATR-FTIR spectroscopy also showed that Protein A proteolysis does not seem to occur under typical CIP conditions (below 1 M NaOH). However, our data revealed that concentrations of NaOH above 0.1 M cause significant changes in Protein A conformation. The addition of >0.4 M trehalose during CIP significantly reduced NaOH-induced ligand unfolding observed for one of the two Protein A resins tested. Such insights could help to optimise CIP protocols in order to extend resin lifetime and reduce mAb production costs. PMID:26159572

  17. A Study of Electrochemical Reduction of Ethylene and PropyleneCarbonate Electrolytes on Graphite Using ATR-FTIR Spectroscopy

    SciTech Connect

    Zhuang, Guorong V.; Yang, Hui; Blizanac, Berislav; Ross Jr.,Philip N.

    2005-05-12

    We present results testing the hypothesis that there is a different reaction pathway for the electrochemical reduction of PC versus EC-based electrolytes at graphite electrodes with LiPF6 as the salt in common. We examined the reduction products formed using ex-situ Fourier Transform Infrared (FTIR) spectroscopy in attenuated total reflection (ATR) geometry. The results show the pathway for reduction of PC leads nearly entirely to lithium carbonate as the solid product (and presumably ethylene gas as the co-product) while EC follows a path producing a mixture of organic and inorganic compounds. Possible explanations for the difference in reaction pathway are discussed.

  18. 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.

  19. Multi-element analysis by portable total reflection X-ray fluorescence spectrometer.

    PubMed

    Liu, Ying; Imashuku, Susumu; Kawai, Jun

    2013-01-01

    Multi-element solutions containing the 11 elements S, K, Sc, V, Mn, Co, Cu, Ga, As, Br and Y were analyzed by a portable total reflection X-ray fluorescence (TXRF) spectrometer. The excitation parameters (glancing angle, operational voltage and current) and sample amount were optimized for the portable TXRF in order to realize the smallest possible detection limits for all elements. The excitation parameter dependencies of the fluorescence signal and background for the detected elements are explained in detail. Background contributed by the sample carrier is also discussed. Consequently, nine elements were detectable at sub-nanogram levels in a single measurement of 10 min under the optimal experimental conditions. The portable TXRF spectrometer was found to be suitable for simultaneous multi-element analysis with low detection limits. The features of high sensitivity, small sample amount required, and fast detection of a wide range of elements make the portable TXRF a valuable tool in various applications, such as field studies in environmental and geological investigations. PMID:23934559

  20. Live-Cell Imaging of the Estrogen Receptor by Total Internal Reflection Fluorescence Microscopy.

    PubMed

    Kisler, Kassandra; Dominguez, Reymundo

    2016-01-01

    Trafficking studies of plasma membrane-localized intracellular estrogen receptors have mainly relied on biochemical and histological techniques to locate the receptor before and after estradiol stimulation. More often than not these experiments were performed using postmortem, lysed, or fixed tissue samples, whose tissue or cellular structure is typically severely altered or at times completely lost, making the definitive localization of estrogen receptors difficult to ascertain. To overcome this limitation we began using total internal reflection fluorescence microscopy (TIRFM) to study the trafficking of plasma membrane estrogen receptors. This real-time imaging approach, described in this chapter, permits observation of live, intact cells while allowing visualization of the steps (in time and spatial distribution) involved in receptor activation by estradiol and movements on and near the membrane. TIRFM yields high-contrast real-time images of fluorescently labeled E6BSA molecules on and just below the cell surface and is ideal for studying estrogen receptor trafficking in living cells. PMID:26585135

  1. 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.

  2. Glutathione immunosensing platform based on total internal reflection ellipsometry enhanced by functionalized gold nanoparticles.

    PubMed

    Garca-Marn, Antonio; Abad, Jos M; Ruiz, Eduardo; Lorenzo, Encarnacin; Piqueras, Juan; Pau, Jos 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 ? and ? 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. PMID:24766219

  3. 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.

  4. Identification of novel insulin mimetic drugs by quantitative total internal reflection fluorescence (TIRF) microscopy

    PubMed Central

    Lanzerstorfer, Peter; Stadlbauer, Verena; Chtcheglova, Lilia A; Haselgrbler, Renate; Borgmann, Daniela; Wruss, Jrgen; Hinterdorfer, Peter; Schrder, Klaus; Winkler, Stephan M; Hglinger, 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

  5. Small-angle measurement with highly sensitive total-internal-reflection heterodyne interferometer.

    PubMed

    Lin, Jiun-You; Liao, Yu-Cheng

    2014-03-20

    In this paper, a high-sensitivity total-internal-reflection (TIR) heterodyne interferometer is proposed for measuring small angles. In the proposed interferometer, a half-wave plate and two quarter-wave plates that exhibit specific optic-axis azimuths are combined to form a phase shifter. When a rhomboid prism is placed between the phase shifter and an analyzer that exhibits suitable transmission-axis azimuth, it shifts and enhances the phase difference of the s- and p-polarization states at double TIR. The enhanced phase difference is dependent on the incident angle; thus small angles can be easily and accurately measured by estimating the phase difference. The experimental results demonstrate the feasibility of this method. Angular resolution and sensitivity levels superior to 1.2×10⁻⁴ deg (2.1×10⁻⁶ rad) and 100 (deg/deg), respectively, were attainable in a dynamic range of 0.5 deg. PMID:24663469

  6. 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.

  7. 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 ?m 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.

  8. Amplification characteristics of a cryogenic Yb?:YAG total-reflection active-mirror laser.

    PubMed

    Furuse, Hiroaki; Sakurai, Toshimitsu; Chosrowjan, Haik; Kawanaka, Junji; Miyanaga, Noriaki; Fujita, Masayuki; Ishii, Shinya; Izawa, Yasukazu

    2014-03-20

    We have studied the amplification characteristics of a cryogenically cooled Yb?:YAG total-reflection active-mirror (TRAM) ceramic laser including wavefront distortion, birefringence loss, small signal gain (SSG), and temperature rise for developing high-performance master oscillator power amplifier (MOPA) systems. A 0.6 mm thick Yb?:YAG ceramic sample was used, and maximum pump intensity ~10??kW/cm was reached. The transmitted wavefront was measured by using a Shack-Hartmann wavefront sensor, and we evaluated the thermal lens focal length and Strehl ratio for different pump conditions. We have also observed a butterfly-like leakage profile of thermally induced birefringence loss at the maximum pump intensity. From SSG measurements, we obtained moderate laser gain of G=3 for one bounce with a near aberration-free wavefront. Gain calculations, which included also temperature dependence of the emission cross section and reabsorption of Yb?:YAG, were in good agreement with the experiments. These experimental results will be useful as benchmark data for numerical simulations of temperature distribution in TRAM and for designing multikilowatt-class high-performance MOPA systems. PMID:24663477

  9. Negligible water surface charge determined using Kelvin probe and total reflection X-ray fluorescence techniques.

    PubMed

    Shapovalov, Vladimir L; Mhwald, Helmuth; Konovalov, Oleg V; Knecht, Volker

    2013-09-01

    The water surface charge has been extensively debated in recent decades. Electrophoretic mobilities of air bubbles in water and disjoining pressures between the surfaces of aqueous films suggest that the surface of water exhibits a significant negative charge. This is commonly attributed to a strong adsorption of hydroxide ions at the interface, though spectroscopic measurements and simulation studies suggest surface depletion of hydroxide ions. Alternatively, the negative surface charge could arise from surface contamination with trace charged surfactants. We have probed the variation in the surface charge of water with pH by measuring surface potentials using the Kelvin probe technique. Independently, the abundance in the interfacial layer of "reporter ions" (Rb(+) and Br(-)), which must be affected by a charged surface, has been monitored using the total reflection X-ray fluorescence (TRXF) technique. Special care was taken to prove the high sensitivity of this technique as well as to avoid surface contaminants. The magnitude of the surface charge was found to be below 1 e per 500 nm(2) (TRXF). No evidence of variations in the surface potential between pH 2-3 and pH 9-12 was detected within the accuracies of the methods (5 mV for Kelvin probe and 2 mV for TRXF). Hence, our findings suggest that the clean water surface exhibits negligible charge in a wide pH range. PMID:23842782

  10. Use of liposomal amplifiers in total internal reflection fluorescence fiber-optic biosensors for protein detection.

    PubMed

    Chang, Ying-Feng; Fu, Chen; Chen, Yi-Ting; Fang-Ju Jou, Amily; Chen, Chii-Chang; Chou, Chien; Annie Ho, Ja-An

    2016-03-15

    Evanescent-wave excited fluorescence technology has been demonstrated to enhance sensitivity and reduce matrix effects, making it suitable for biosensor development. In this study, we developed a liposome-based, total internal reflection fluorescence, fiber-optic biosensor (TIRF-FOB) for protein detection, which integrates a liposomal amplifier and sandwich immunoassay format with TIRF-FOB. In addition, the antibody-tagged and fluorophore-entrapped liposomes for heterogeneous detection of target molecules were designed and synthesized. This biosensor successfully detected the target protein (model analyzed here is IgG) with a limit of detection (LOD) of 2.0 attomoles for the target protein (equivalent to 2.0 pg/mL of protein presented in 150 μL of sample solution). The features of this ultra-sensitive liposomal TIRF-FOB are (i) fluorescence is excited via evanescent waves and amplified via liposomes; (ii) the use of two polyclonal antibodies in the sandwich assay format increases the specificity and lowers the cost of our assay. Based on the exceptional detection sensitivity and cost-effectiveness, we believe that the proposed biosensor has great potential as a practical, clinical diagnostic tool in the near future. PMID:26595485

  11. Tunable Wide-Angle Tunneling in Graphene-Assisted Frustrated Total Internal Reflection

    PubMed Central

    Tran, Thang Q.; Lee, Sangjun; Heo, Hyungjun; Kim, Sangin

    2016-01-01

    Electrically tunable permittivity of graphene provides an excellent tool in photonic device design. Many previous works on graphene-based photonic devices relied on variable absorption in graphene, which is naturally small in the optical region, and resonant structures to enhance it. Here we proposed a novel scheme to control evanescent coupling strength by inserting two graphene layers to a frustrated total internal reflection (FTIR) configuration. The resulting structure behaves in a drastically different way from the original FTIR: optical transmission though the structure can be electrically controlled from ~10−5 to ~1 with little dependency on angle of incidence. This unique feature stems from the fact that the permittivity of doped graphene can be close to zero at a certain photon energy. The electrical controllability of evanescent coupling strength can enable novel design of optical devices. As a proof-of-concept, we designed a waveguide-type optical modulator of a novel operation principle: transmission modulation depends on the electrically controlled existence of a guided-mode of the waveguide, not the variation of the ohmic loss of graphene, resulting in a low insertion loss and a small device footprint. PMID:26815116

  12. Tunable Wide-Angle Tunneling in Graphene-Assisted Frustrated Total Internal Reflection.

    PubMed

    Tran, Thang Q; Lee, Sangjun; Heo, Hyungjun; Kim, Sangin

    2016-01-01

    Electrically tunable permittivity of graphene provides an excellent tool in photonic device design. Many previous works on graphene-based photonic devices relied on variable absorption in graphene, which is naturally small in the optical region, and resonant structures to enhance it. Here we proposed a novel scheme to control evanescent coupling strength by inserting two graphene layers to a frustrated total internal reflection (FTIR) configuration. The resulting structure behaves in a drastically different way from the original FTIR: optical transmission though the structure can be electrically controlled from ~10(-5) to ~1 with little dependency on angle of incidence. This unique feature stems from the fact that the permittivity of doped graphene can be close to zero at a certain photon energy. The electrical controllability of evanescent coupling strength can enable novel design of optical devices. As a proof-of-concept, we designed a waveguide-type optical modulator of a novel operation principle: transmission modulation depends on the electrically controlled existence of a guided-mode of the waveguide, not the variation of the ohmic loss of graphene, resulting in a low insertion loss and a small device footprint. PMID:26815116

  13. Extraction of light trapped due to total internal reflection using porous high refractive index nanoparticle films

    NASA Astrophysics Data System (ADS)

    Mao, Peng; Sun, Fangfang; Yao, Hanchao; Chen, Jing; Zhao, Bo; Xie, Bo; Han, Min; Wang, Guanghou

    2014-06-01

    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. Parasitic Oscillations And Amplified Spontaneous Emission In Face-Pumped Total Internal Reflection Lasers

    NASA Astrophysics Data System (ADS)

    Brown, D. C.; Benfey, D. P.; Gehm, W. J.; Holmes, D. H.; Lee, K. K.

    1987-04-01

    Parasitic oscillations and amplified spontaneous emission (ASE) can often strongly influence the operation and efficiency of laser devices, as has been shown previously for disk and active-mirror amplifiers. Here we report the first comprehensive investigation of those phenomena in total internal reflection (TIR) face-pumped lasers. The results to be presented here were made possible by the development of two three-dimensional computer codes. The first (PARA) systematically searches for parasitic oscillations in slab lasers and determines the gain required to reach threshold. Our second code (AMSPE) is a three dimensional raytrace model which includes temporal gain and allows for non-uniform gain profiles. AMSPE calculates the gain depletion as well as changes in spatial gain profile and thus the decrease in amplifier efficiency as a function of a number of critical parameters such as slab aspect ratio, spontaneous emission spectral profile, and slab face angle. In this paper we first review the classes of parasitics in slab lasers and show how symmetry breaking can significantly increase the energy storage capability of such deyices. We then review the construction of the AMSPE code and show how it may be used to identify maximum efficiency slab laser configurations.

  15. Tunable Wide-Angle Tunneling in Graphene-Assisted Frustrated Total Internal Reflection

    NASA Astrophysics Data System (ADS)

    Tran, Thang Q.; Lee, Sangjun; Heo, Hyungjun; Kim, Sangin

    2016-01-01

    Electrically tunable permittivity of graphene provides an excellent tool in photonic device design. Many previous works on graphene-based photonic devices relied on variable absorption in graphene, which is naturally small in the optical region, and resonant structures to enhance it. Here we proposed a novel scheme to control evanescent coupling strength by inserting two graphene layers to a frustrated total internal reflection (FTIR) configuration. The resulting structure behaves in a drastically different way from the original FTIR: optical transmission though the structure can be electrically controlled from ~10‑5 to ~1 with little dependency on angle of incidence. This unique feature stems from the fact that the permittivity of doped graphene can be close to zero at a certain photon energy. The electrical controllability of evanescent coupling strength can enable novel design of optical devices. As a proof-of-concept, we designed a waveguide-type optical modulator of a novel operation principle: transmission modulation depends on the electrically controlled existence of a guided-mode of the waveguide, not the variation of the ohmic loss of graphene, resulting in a low insertion loss and a small device footprint.

  16. A Platform for Combined DNA and Protein Microarrays Based on Total Internal Reflection Fluorescence

    PubMed Central

    Asanov, Alexander; Zepeda, Anglica; 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

  17. 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.

  18. A label-free continuous total-internal-reflection-fluorescence-based immunosensor.

    PubMed

    Engstrm, Henrik A; Andersson, Per Ola; Ohlson, Sten

    2006-10-15

    In this study, we continuously monitored, second-by-second, concentration changes of two different carbohydrates (maltose and panose) by using monoclonal antibodies in an optical immunosensor based on total internal reflection fluorescence. Earlier studies have demonstrated that these antibodies increase their intrinsic tryptophan fluorescence upon binding of carbohydrate antigens. Using the four immobilized monoclonal antibodies with low affinities (K(d)>10(-6)M), fast kinetics (k(off)>1s(-1)), and high reversibility gave opportunities for developing a continuous immunosensor without any need for regeneration. Since intrinsic fluorescence was used, no extrinsic labeling was necessary. Sensitivity was in the range of 1-5 microM for panose, and 10-15 microM for maltose and the loss of intensity was as low as 3.5% per hour during measurements. Calculations of DeltaH degrees and DeltaS degrees from the temperature dependence of K(d) indicated an enthalpic driven antigen-antibody binding event that is diminished upon antibody immobilization. We feel certain that weakly interacting antibodies can be used in future applications for continuous monitoring where there is a need to achieve instantaneous information on the concentration of an analyte. PMID:16934212

  19. 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.

  20. Elemental concentration analysis in prostate tissues using total reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Leito, 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, So 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 (?=0.05) between the groups studied.

  1. Design and Construction of a Multi-wavelength, Micromirror Total Internal Reflectance Fluorescence Microscope

    PubMed Central

    Larson, Joshua; Kirk, Matt; Drier, Eric A.; OBrien, 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

  2. Elucidation of Perovskite Film Micro-Orientations Using Two-Photon Total Internal Reflectance Fluorescence Microscopy

    SciTech Connect

    Watson, Brianna R; Yang, Bin; Xiao, Kai; Ma, Yingzhong; Doughty, Benjamin L; Calhoun, Tessa R

    2015-01-01

    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. 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.

  3. 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 200nm 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. PMID:26002253

  4. Determination of mercury by total-reflection X-ray fluorescence using amalgamation with gold

    NASA Astrophysics Data System (ADS)

    Bennun, L.; Gomez, J.

    1997-07-01

    Analysis by total-reflection X-ray fluorescence (TXRF) is unsuitable for determining mercury concentrations because the usual sample preparation produces evaporation and loss of this element as a consequence of its high vapour pressure and low boiling point. A method that has been developed to achieve this determination involves forming an amalgam while a thin layer of silver (obtained by sputtering or evaporation) is in contact with an ionic solution of Hg; subsequently, a traditional TXRF analysis is performed. This was the first method reported in the literature to apply the TXRF technique for reliably determining mercury concentrations with high sensitivity. This work shows how a similar procedure may be employed to measure mercury concentrations. This second method involves forming an amalgam of gold using microlitre quantities of the solution to be analysed. As gold is a highly malleable material, it allows the production of very thin films, the weight of which is a few orders of magnitude higher than the mass of mercury present in the amalgam. The determination is performed in the usual way using the TXRF technique. The sensitivity of this method (? 5 ppm) is inferior to that of the former method, and data processing is quite difficult because the peaks for mercury and gold overlap, but the experiment is simple to execute and improved sensitivity is expected to be attained by forming the amalgam with larger volumes of sample and with a more responsive data processing scheme.

  5. Surface complexation of mellitic acid to goethite: an attenuated total reflection Fourier transform infrared study.

    PubMed

    Johnson, Bruce B; Sjberg, Staffan; Persson, Per

    2004-02-01

    The nature of the interaction between mellitic acid (benzene hexacarboxylic acid) and the common soil mineral goethite (alpha-FeOOH) has been investigated as a function of pH and ionic strength by use of attenuated total reflection Fourier transform infrared spectroscopy. Molecular orbital calculations of the theoretical vibrational frequencies of the mellitate ion (L6-) and dihydrogen mellitate (H2L4-) have allowed the measured absorption frequencies to be accurately assigned. At pH values above 6, adsorption involves outer-sphere complexation of the deprotonated L6- ion. At lower pH values, there is evidence of a second outer-sphere surface complex involving a partially protonated species, although the extent of protonation of the surface species is significantly less than that found for the solution species at the same pH. While there is no evidence of inner-sphere complexation, increasing the ionic strength to 2.0 M does not displace the adsorbed species but does increase the fraction present on the surface as the fully deprotonated L6-. The small effect of ionic strength suggests that the adsorptive interaction, although outer-sphere in character, is still relatively strong, which indicates that hydrogen bonds may play a significant role. Hydrogen bonding may also help to account for the observed outer-sphere complexation at pH values above the pHiep of goethite. PMID:15773110

  6. 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

    TiO? nanoparticle layers composed of columnar TiO? 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 TiO? 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 TiO? nanoparticles in the nanoporous structures, was proposed. The porous TiO? 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 TiO? nanoparticle porous layers can be a supplement to the microscale texturing process for light extraction enhancement. PMID:24927071

  7. Changepoint Analysis for Single-Molecule Polarized Total Internal Reflection Fluorescence Microscopy Experiments

    PubMed Central

    Beausang, John F.; Goldman, Yale E.; Nelson, Philip C.

    2011-01-01

    The experimental study of individual macromolecules has opened a door to determining the details of their mechanochemical operation. Motor enzymes such as the myosin family have been particularly attractive targets for such study, in part because some of them are highly processive and their product is spatial motion. But single-molecule resolution comes with its own costs and limitations. Often, the observations rest on single fluorescent dye molecules, which emit a limited number of photons before photobleaching and are subject to complex internal dynamics. Thus, it is important to develop methods that extract the maximum useful information from a finite set of detected photons. We have extended an experimental technique, multiple polarization illumination in total internal reflection fluorescence microscopy (polTIRF), to record the arrival time and polarization state of each individual detected photon. We also extended an analysis technique, previously applied to FRET experiments, that optimally determines times of changes in photon emission rates. Combining these improvements allows us to identify the structural dynamics of a molecular motor (myosin V) with unprecedented detail and temporal resolution. PMID:21187234

  8. Novel Bio, Chemical, Environmental Sensing Based on New Model of Total Internal Reflection in Turbid Media

    NASA Astrophysics Data System (ADS)

    Bali, Samir; Judge, Patrick; Phillip, Nathan; Boivin, Jordan; Scaffidi, Jonathan; Berberich, Jason; Bali, Lalit

    2014-05-01

    We have initiated a collaborative experimental research program that combines new advances in optical physics, field portable chemical analysis, and biosensing. Our goal is to discover and characterize new optical sensing methodologies in opaque, highly scattering (i.e., ``turbid'') media, and demonstrate new paradigms for optical sensing in research and industry. We have three specific objectives. First, we propose to fully characterize and validate a new model of total internal reflection (TIR) from highly turbid media thus enabling a first demonstration of non-invasive, in-situ, real-time particle sizing for the case of arbitrary scattering particle size-a holy grail in colloidal science. Second, we propose to implement a first demonstration of real-time non-invasive measurement of nanoparticle aggregation in highly turbid media. Third, we propose to use our new sensing methodology to demonstrate real-time in-situ label-free monitoring of molecular interactions and adsorption at surfaces. We gratefully acknowledge support from the American Chemical Society Petroleum Research Fund and Miami University's Interdisciplinary Roundtable Fund. We also gratefully acknowledge experimental help from the Miami University Instrumentation Laboratory.

  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. Application of Near Infrared Reflectance Spectroscopy on Determination of Moisture, Total oil and Protein Contents of In-shell Peanuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Moisture, total oil and protein content of peanuts are important factors in peanut grading. A method that could rapidly and nondestructively measure these parameters for in-shell peanuts would be extremely useful. NIR reflectance spectroscopy was used to analyze the moisture, total oil and protein ...

  11. 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.

  12. Rapid discrimination of maggots utilising ATR-FTIR spectroscopy.

    PubMed

    Pickering, Claire L; Hands, James R; Fullwood, Leanne M; Smith, Judith A; Baker, Matthew J

    2015-04-01

    Entomological evidence is used in forensic investigations to indicate time since death. The species and age of maggots or flies that are present at the scene can be used when estimating how much time has passed since death. Current methods that are used to identify species and developmental stage of larvae and fly samples are highly subjective, costly and often time consuming processes and require the expertise of an entomologist or species identification via DNA analysis. The use of vibrational spectroscopy, as an alternative identification method, would allow for a quicker, cheaper and less subjective technique and would allow entomological evidence to be used more commonly in the forensic process. This proof of principle study shows the potential for using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) as a rapid tool for differentiating between various species of larvae, such as those commonly found at crime scenes. The proposed regime would provide a rapid and valuable tool resulting in reduced time for both species identification and life cycle determination, particularly in forensic situations. PMID:25703014

  13. Application of FTIR-ATR Spectroscopy to Determine the Extent of Lipid Peroxidation in Plasma during Haemodialysis

    PubMed Central

    Oleszko, Adam; Olsztyńska-Janus, Sylwia; Grzeszczuk-Kuć, Karolina; Bujok, Jolanta; Gałecka, Katarzyna; Czerski, Albert; Witkiewicz, Wojciech; Komorowska, Małgorzata

    2015-01-01

    During a haemodialysis (HD), because of the contact of blood with the surface of the dialyser, the immune system becomes activated and reactive oxygen species (ROS) are released into plasma. Particularly exposed to the ROS are lipids and proteins contained in plasma, which undergo peroxidation. The main breakdown product of oxidized lipids is the malondialdehyde (MDA). A common method for measuring the concentration of MDA is a thiobarbituric acid reactive substances (TBARS) method. Despite the formation of MDA in plasma during HD, its concentration decreases because it is removed from the blood in the dialyser. Therefore, this research proposes the Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy, which enables determination of primary peroxidation products. We examined the influence of the amount of hydrogen peroxide added to lipid suspension that was earlier extracted from plasma specimen on lipid peroxidation with use of TBARS and FTIR-ATR methods. Linear correlation between these methods was shown. The proposed method was effective during the evaluation of changes in the extent of lipid peroxidation in plasma during a haemodialysis in sheep. A measurement using the FTIR-ATR showed an increase in plasma lipid peroxidation after 15 and 240 minutes of treatment, while the TBARS concentration was respectively lower. PMID:25961007

  14. Integrity and stability studies of precipitated rhBMP-2 microparticles with a focus on ATR-FTIR measurements.

    PubMed

    Schwartz, Daniel; Sofia, Susan; Friess, Wolfgang

    2006-07-01

    A major obstacle in the development of protein drug formulations is the need to maintain the native, active protein structure both during the formulation process and upon long time storage. Controlled precipitation was evaluated for its potential to supply stable microparticulate formulations of bone-regenerating recombinant human Bone Morphogenetic Protein-2 (rhBMP-2). Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) did provide insight into the protein formulation and stability. Temperature dependent ATR-FTIR measurements and DSC measurements allow for the study of changes in the protein structure during melting. To address the question of isomerization, peptide mapping was performed, and protein aggregation was monitored by size exclusion chromatography (SEC). It could be demonstrated by ATR-FTIR that controlled precipitation did not harm the protein and the process is fully reversible. DSC measurements further confirmed these findings. No changes in the transition temperature and process were observed after precipitation and redissolution. Upon storage, isomerization and aggregation could be detected, but to a lower extent in the precipitated formulation as compared to a solution reference. Thus, controlled precipitation of rhBMP-2 is fully reversible and has the potential as alternative formulation tool for the generation of a microparticulate drug delivery system. PMID:16675211

  15. ATR-FTIR Spectroscopy Highlights the Problem of Distinguishing Between Exophiala dermatitidis and E. phaeomuriformis Using MALDI-TOF MS.

    PubMed

    Ergin, Çağrı; Gök, Yaşar; Bayğu, Yasemin; Gümral, Ramazan; Özhak-Baysan, Betil; Döğen, Aylin; Öğünç, Dilara; Ilkit, Macit; Seyedmousavi, Seyedmojtaba

    2016-02-01

    The present study compared two chemical-based methods, namely, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, to understand the misidentification of Exophiala dermatitidis and Exophiala phaeomuriformis. The study utilized 44 E. dermatitidis and 26 E. phaeomuriformis strains, which were partially treated with strong acids and bases for further evaluation. MALDI-TOF MS and ATR-FTIR spectroscopy data of the two Exophiala species were compared. Data groupings were observed for the chromic acid- and nitric acid-treated species when the black yeast sources were categorized as creosoted-oak sleepers, concrete sleepers, or dishwasher isolates. The MALDI-TOF MS data for the metalloenzyme-containing regions were consistent with the ATR-FTIR spectroscopy data. These results indicated that environmental isolates might contain metals not found in human isolates and might interfere with chemical-based identification methods. Therefore, MALDI-TOF MS reference libraries should be created for clinical strains and should exclude petroleum-associated environmental isolates. PMID:26373644

  16. On the differentiation of diffusion bond strength using the total acoustic energy reflected from the bond

    SciTech Connect

    Ojard, G.C.; Buck, O.; Rehbein, D.K.; Hughes, M.S.

    1992-12-31

    Single frequency reflection coefficients and reflected energy over a broad acoustic band (2-15 MHz), and the mechanical bond strength were evaluated on diffusion bonds in Cu/Cu, Cu/Ni, and Ti-6Al-4V/self. Results indicate that energy data are more sensitive to small bond strength changes as predicted by Parseval`s theorem. In all cases, the energy reflected mainly originates at voids still present at the original interface location. Other microstructural features caused by the interdiffusion appear to diminish the reflected energy. 7 refs., 4 figs.

  17. 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 lowcomparable to that of carotenoids and significantly less than that of (bacterio)chlorophyllsthese 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, ?-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

  18. 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

  19. Total reflection X-ray fluorescence spectrometers for multielement analysis: status of equipment

    NASA Astrophysics Data System (ADS)

    Ayala Jimnez, 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 production of this instrument. The detection limits reported in the literature are presented; pricing, analytical capability, ease of operation, calibration and optical alignment as well as technical support are also discussed.

  20. 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. PMID:26538436

  1. 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.

  2. Actin dynamics at the living cell submembrane imaged by total internal reflection fluorescence photobleaching.

    PubMed

    Sund, S E; Axelrod, D

    2000-09-01

    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

  3. 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.

  4. Measurements of long-range interactions between protein-functionalized surfaces by total internal reflection microscopy.

    PubMed

    Wang, Zhaohui; Gong, Xiangjun; Ngai, To

    2015-03-17

    Understanding the interaction between protein-functionalized surfaces is an important subject in a variety of protein-related processes, ranging from coatings for biomedical implants to targeted drug carriers and biosensors. In this work, utilizing a total internal reflection microscope (TIRM), we have directly measured the interactions between micron-sized particles decorated with three types of common proteins concanavalin A (ConA), bovine serum albumin (BSA), lysozyme (LYZ), and glass surface coated with soy proteins (SP). Our results show that the protein adsorption greatly affects the charge property of the surfaces, and the interactions between those protein-functionalized surfaces depend on solution pH values. At pH 7.5-10.0, all these three protein-functionalized particles are highly negatively charged, and they move freely above the negatively charged SP-functionalized surface. The net interaction between protein-functionalized surfaces captured by TIRM was found as a long-range, nonspecific double-layer repulsion. When pH was decreased to 5.0, both protein-functionalized surfaces became neutral and double-layer repulsion was greatly reduced, resulting in adhesion of all three protein-functionalized particles to the SP-functionalized surface due to the hydrophobic attraction. The situation is very different at pH = 4.0: BSA-decorated particles, which are highly charged, can move freely above the SP-functionalized surfaces, while ConA- and LYZ-decorated particles can only move restrictively in a limited range. Our results quantify these nonspecific kT-scale interactions between protein-functionalized surfaces, which will enable the design of surfaces for use in biomedical applications and study of biomolecular interactions. PMID:25719226

  5. Micro attenuated total reflection spectra of bulk silica glass: effects of experimental conditions and glass thermal history on appearance of a surface polariton in the Si-O stretching region.

    PubMed

    Stolov, Andrei A; Simoff, Debra A

    2008-06-01

    Micro attenuated total reflection (micro-ATR) spectra of bulk silica glass were investigated for a variety of samples, including fused quartz slides, an optical fiber preform, and a series of optical fiber claddings. The experiments were performed at varied distances between the internal reflection element (IRE) and the sample. At certain conditions, a surface polariton peak is observed in the region 1100-1160 cm(-1). The position of this peak is affected by the type of IRE (Ge, Si, ZnSe, or diamond), IRE-sample distance, and the material used as an interlayer between the IRE and the sample (air or Nujol). From the experimental data, the dielectric constant of silica is determined in the region between 1100 and 1160 cm(-1). The polariton peak is also observed when glass is coated with a thin (40 nm) layer of carbon. It has also been found that the polariton peak position is affected by the thermal history of the glass, and an attempt is made to correlate the observed changes with the glass fictive temperature. PMID:18559149

  6. Characterization of urban air pollution by total reflection X-ray fluorescence*1

    NASA Astrophysics Data System (ADS)

    Schmeling, Martina

    2004-08-01

    Besides photochemical smog, particulate air pollution is a constantly growing problem in urban areas. The particulate matter present in pollution events contains often toxic or health impacting elements and is responsible for low visibility, might be triggering respiratory diseases like asthma, and can play an important role in formation or duration of smog events. To characterize particulate pollution in two different cities, samples were taken during intensive field campaigns in Chicago, IL, in 2002 and Phoenix, AZ, in 2001. Both cities experience regularly photochemical smog events as well as particulate pollution, but show very different meteorological and topographical conditions. Therefore it is expected that the particulate composition varies significantly, providing information about different pollution forms. Sampling took place in both cases at elevated locations and had a temporal resolution of 1.5 h and 1 h, respectively. The samples were analyzed by total reflection X-ray fluorescence after digestion of the filter matrix. As expected the elemental composition of particulate matter varied between both cities substantially with Phoenix showing a higher abundance of crustal elements, and Chicago enrichment in anthropogenically produced ones. In both cities diurnal patterns were found, exerting maxima in the morning and minima in the early afternoon. The diurnal pattern was much more regularly and also more strongly pronounced in Phoenix. Phoenix's valley location permits for a more stable nocturnal boundary layer to build up during the night thus trapping particulates efficiently during this time, until mixing occurs in the early morning hours and the residual layer lifts. In Chicago, the diurnal variation was less extreme, but another pattern determines the situation with the lake breeze. The lake breeze corresponds to a shift in wind direction towards the east, i.e. from Lake Michigan during the late morning. It was found that certain elemental species were enriched during a lake breeze event whereas this was not the case during other days. In conclusion, the low sample mass needed for TXRF analysis and the corresponding short sampling times, permitted the observation and characterization of local meteorological patterns in Phoenix and in Chicago.

  7. Colloidal force measurements using atomic force microscopy and total internal reflection microscopy

    NASA Astrophysics Data System (ADS)

    Dagastine, Raymond Riley

    Measurements of colloidal forces at deformable interfaces (compared to rigid systems) are complicated by deformation of the interfaces making both measurement and interpretation more difficult, although understanding the colloidal forces at a liquid-liquid and liquid-gas interface is relevant to many industrial processes. Atomic Force Microscopy (AFM) measurements between a rigid probe and a deformable interface have become commonplace, yet interpretation of the data is not straightforward due to the deformation. A semianalytic model was developed to predict the behavior of this type of AFM force measurement. The results of the theory demonstrate that analysis techniques for rigid systems are not valid for deformable cases. A method for extracting quantitative data from an AFM measurement was developed using the above model, where planar interaction energy per unit area was deconvoluted from the AFM force measurement without any prior knowledge of the interaction energy. Interaction energies extracted from measurements with an anionic surfactant absorbed at the oil water interface compared favorably to theoretical predictions for van der Waals and electrostatic force models. The experimental results indicated that local surface tension changes or local charge rearrangement of the surfactant occur during the force measurement. Electrostatic forces and steric forces were observed in interaction energies extracted from measurements with a tri-block copolymer (Pluronic F-108) absorbed at both interfaces in the presence of an inorganic salt. The decay lengths of the electrostatic force indicated that the oil-water interface was not charged, consistent with a nonionic polymer absorbed at the oil-water interface. An existing Total Internal Reflection Microscopy (TIRM) fluid cell was modified to measure the interaction energy of an oil droplet levitated below a flat silica plate. Methods to improve the experiment to minimize noise, which obscured most quantitative analyses on the data, were discussed. A novel method to account for the effects of surface roughness on van der Waals force predictions using Lifshitz theory was developed. The model behavior was probed at contact by variation of the type of surface roughness and at larger separations by comparison to previously published TIRM measurements of retarded van der Waals forces between a sphere and plate.

  8. Prospects for the Use of ATR Inhibitors to Treat Cancer

    PubMed Central

    Wagner, Jill M.; Kaufmann, Scott H.

    2010-01-01

    ATR is an apical kinase in one of the DNA-damage induced checkpoint pathways. Despite the development of inhibitors of kinases structurally related to ATR, as well as inhibitors of the ATR substrate Chk1, no ATR inhibitors have yet been developed. Here we review the effects of ATR downregulation in cancer cells and discuss the potential for development of ATR inhibitors for clinical use.

  9. ATR-FTIR measurements of albumin and fibrinogen adsorption: Inert versus calcium phosphate ceramics.

    PubMed

    Boix, Marcel; Eslava, Salvador; Costa Machado, Gil; Gosselin, Emmanuel; Ni, Na; Saiz, Eduardo; De Coninck, Jol

    2015-11-01

    Arthritis, bone fracture, bone tumors and other musculoskeletal diseases affect millions of people across the world. Nowadays, inert and bioactive ceramics are used as bone substitutes or for bone regeneration. Their bioactivity is very much dictated by the way proteins adsorb on their surface. In this work, we compared the adsorption of albumin and fibrinogen on inert and calcium phosphates ceramics (CaPs) using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to follow in situ protein adsorption on these materials. To this effect, we developed a sol-gel technique to control the surface chemistry of an ATR-FTIR detector. Hydroxyapatite adsorbed more albumin and ?-tricalcium phosphate adsorbed more fibrinogen. Biphasic calcium phosphate presented the lowest adsorption among CaP for both proteins, illustrating the effect of surface heterogeneities. Inert ceramics adsorbed a lower amount of both proteins compared with bioactive ceramics. A significant change was observed in the conformation of the adsorbed protein versus the surface chemistry. Hydroxyapatite produced a larger loss of ?-helix structure on albumin and biphasic calcium phosphate reduced ?-sheet percentage on fibrinogen. Inert ceramics produced large ?-helix loss on albumin and presented weak interaction with fibrinogen. Zirconia did not adsorb albumin and titanium dioxide promoted huge denaturalization of fibrinogen. PMID:25940865

  10. Evanescent wave absorption measurements of corroded materials using ATR and optical fibers

    NASA Astrophysics Data System (ADS)

    Namkung, Juock; Hoke, Mike; Schwartz, Andy

    2011-06-01

    The purpose of this research effort is to develop an in-situ corrosion sensing capability. The technique will permit detection of corrosion on and within aircraft structures. This includes component junctions that are susceptible to corrosion but which are not accessible for visual inspection. The prototype experimental configuration we are developing includes long wave infrared transmitting optical fiber probes interfaced with a Fourier Transform Infrared (FTIR) interferometer for evanescent wave absorption spectroscopic measurements. The mature and fielded technique will allow periodic remote sensing for detection of corrosion and for general onboard aircraft structural health monitoring. An experimental setup using an Attenuated Total Reflection (ATR) crystal integrated with an FTIR spectrometer has been assembled. Naturally occurring corrosion including Aluminum Hydroxide [Al(OH)3] is one of the main corrosion products of aluminum the principle structural metal of aircraft. Absorption spectra of our model corrosion product, pure Al(OH)3, have been collected with this ATR/FTIR experimental setup. The Al(OH)3spectra serve as reference spectral signatures. The spectra of corrosion samples from a simulated corrosion process have been collected and compared with the reference Al(OH)3 spectra. Also absorption spectra of naturally occurring corrosion collected from a fielded corroded aircraft part have been obtained and compared with the spectra from the simulated corrosion.

  11. Rapid detection of melamine adulteration in dairy milk by SB-ATR-Fourier transform infrared spectroscopy.

    PubMed

    Jawaid, Sana; Talpur, Farah N; Sherazi, S T H; Nizamani, Shafi M; Khaskheli, Abid A

    2013-12-01

    Melamine is a nitrogenous chemical substance used principally as a starting material for the manufacture of synthetic resins. Due to its very high proportion of nitrogen melamine has been added illegitimately to foods and feeds to increase the measured protein content, which determines the value of the product. These issues prompted private as well as governmental laboratories to develop methods for the analysis of melamine in a wide variety of food products and ingredients. Owing to this fact present study is aimed to use single bounce attenuated total reflectance (SB-ATR) Fourier transform infrared spectroscopy (FTIR) method as an effective rapid tool for the detection and quantification of melamine in milk (liquid and powder). Partial least-squares (PLS) models were established for correlating spectral data to melamine concentration with R(2)>0.99, and RMSEC 0.370. Linear calibration curves were obtained over the calibration range of 25-0.0625%. The LOD and LOQ of the method was 0.00025% (2.5 ppm) and 0.0015% (15 ppm) respectively. Proposed SB-ATR-FTIR method requires little or no sample preparation with an assay time of 1-2 min. PMID:23871060

  12. Water content determination of superdisintegrants by means of ATR-FTIR spectroscopy.

    PubMed

    Szakonyi, G; Zelk, R

    2012-04-01

    Water contents of superdisintegrant pharmaceutical excipients were determined by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy using simple linear regression. Water contents of the investigated three common superdisintegrants (crospovidone, croscarmellose sodium, sodium starch glycolate) varied over a wide range (0-24%, w/w). In the case of crospovidone three different samples from two manufacturers were examined in order to study the effects of different grades on the calibration curves. Water content determinations were based on strong absorption of water between 3700 and 2800 cm?, other spectral changes associated with the different compaction of samples on the ATR crystal using the same pressure were followed by the infrared region between 1510 and 1050 cm?. The calibration curves were constructed using the ratio of absorbance intensities in the two investigated regions. Using appropriate baseline correction the linearity of the calibration curves was maintained over the entire investigated water content regions and the effect of particle size on the calibration was not significant in the case of crospovidones from the same manufacturer. The described method enables the water content determination of powdered hygroscopic materials containing homogeneously distributed water. PMID:22361662

  13. Two-dimensional attenuated total reflection infrared correlation spectroscopy study of desorption process of water-soaked cotton fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two-dimensional (2D) correlation analysis was applied to characterize the ATR spectral intensity fluctuations of native cotton fibers with various water contents. Prior to 2D analysis, the spectra were leveled to zero at the peak intensity of 1800 cm-1 and then were normalized at the peak intensity ...

  14. A plastic total internal reflection-based photoluminescence device for enzymatic biosensors

    NASA Astrophysics Data System (ADS)

    Thakkar, Ishan G.

    Growing concerns for quality of water, food and beverages in developing and developed countries drive sizeable markets for mass-producible, low cost devices that can measure the concentration of contaminant chemicals in water, food, and beverages rapidly and accurately. Several fiber-optic enzymatic biosensors have been reported for these applications, but they exhibit very strong presence of scattered excitation light in the signal for sensing, requiring expensive thin-film filters, and their non-planar structure makes them challenging to mass-produce. Several other planar optical waveguide-based biosensors prove to be relatively costly and more fragile due to constituent materials and the techniques involved in their fabrication. So, a plastic total internal reflection (TIR)-based low cost, low scatter, field-portable device for enzymatic biosensors is fabricated and demonstrated. The design concept of the TIR-based photoluminescent enzymatic biosensor device is explained. An analysis of economical materials with appropriate optical and chemical properties is presented. PMMA and PDMS are found to be appropriate due to their high chemical resistance, low cost, high optical transmittance and low auto-fluorescence. The techniques and procedures used for device fabrication are discussed. The device incorporated a PMMA-based optical waveguide core and PDMS-based fluid cell with simple multi-mode fiber-optics using cost-effective fabrication techniques like molding and surface modification. Several techniques of robustly depositing photoluminescent dyes on PMMA core surface are discussed. A pH-sensitive fluorescent dye, fluoresceinamine, and an O2-sensitive phosphorescent dye, Ru(dpp) both are successfully deposited using Si-adhesive gel-based as well as HydroThane-based deposition methods. Two different types of pH-sensors using two different techniques of depositing fluoresceinamine are demonstrated. Also, the effect of concentration of fluoresceinamine-dye molecules on fluorescence intensity and scattered excitation light intensity is investigated. The fluorescence intensity to the scattered excitation light intensity ratio for dye deposition is found to increase with increase in concentration. However, both the absolute fluorescence intensity and absolute scatter intensity are found to decrease in different amounts with an increase in concentration. An enzymatic hydrogen peroxide (H2O2) sensor is made and demonstrated by depositing Ruthenium-based phosphorescent dye (Ru(dpp) 3) and catalase-enzyme on the surface of the waveguide core. The O 2-sensitive phosphorescence of Ru(dpp)3 is used as a transduction signal and the catalase-enzyme is used as a bio-component for sensing. The H2O2 sensor exhibits a phosphorescence signal to scattered excitation light ratio of 100+/-18 without filtering. The unfiltered device demonstrates a detection limit of (2.20+/-0.6) microM with the linear range from 200microM to 20mM. An enzymatic lactose sensor is designed and characterized using Si-adhesive gel based Ru(dpp)3 deposition and oxidase enzyme. The lactose sensor exhibits the linear range of up to 0.8mM, which is too small for its application in industrial process control. So, a flow cell-based sensor device with a fluid reservoir is proposed and fabricated to increase the linear range of the sensor. Also, a multi-channel pH-sensor device with four channels is designed and fabricated for simultaneous sensing of multiple analytes.

  15. Mobility and surfactant migration in EA/MAA latex films; ATR FT-IR spectroscopic study

    SciTech Connect

    Thorstenson, T.A.; Tebelius, L.K.; Urban, M.W.

    1993-12-31

    Although numerous factors such as compatibility, mechanical deformation, and the nature of the substrate have been addressed with respect to surfactant migration and distribution within latex films, latex suspension stability and the effects of particle flocculation are also key issues. In this paper, surfactant behavior in an ethyl acrylate/methacrylic acid/sodium dioctyl sulfosuccinate (EA/MAA/SDOSS) latex system is monitored as a function of stability of the liquid latex suspensions. Particle size data obtained using light scattering reveals an appreciable degree of flocculation over the period of study. It is found that flocculation is paralleled by a significantly increased degree of interfacial surfactant enrichment, a monitored by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR). It is concluded that the enhanced surfactant exudation observed for flocculated latexes is due to displacement of adsorbed surfactant during the course of flocculation.

  16. An in situ ATR-IR spectroscopy study of aluminas under aqueous phase reforming conditions.

    PubMed

    Koichumanova, K; Sai Sankar Gupta, K B; Lefferts, L; Mojet, B L; Seshan, K

    2015-10-01

    High temperature/pressure in situ Attenuated Total Reflection Infrared (ATR-IR) spectroscopy was used to investigate the phase transformation of support ?-Al2O3 into boehmite (AlO(OH)) under the hydrothermal conditions of aqueous phase reforming (APR). Activation energy barriers of boehmite formation in hot compressed water at temperatures between 150 and 180 C were calculated to be 15.9 4.8 kJ mol(-1) for ?-Al2O3 and 43.2 4.3 kJ mol(-1) for Pt/?-Al2O3. The influence of Pt particles is suggested to slow down the phase transformation by selective blockage of the surface nucleation sites. The presence of ethylene glycol has also an inhibiting effect on the transformation due to the carbon deposits formed on the oxide surface. Post-mortem analysis using Raman spectroscopy, (1)H and (27)Al MAS NMR confirms the formation of boehmite. PMID:26305344

  17. FTIR-ATR evaluation of topical skin protectants useful for sulfur mustard and related compounds

    NASA Astrophysics Data System (ADS)

    Braue, Ernest H., Jr.; Litchfield, Marty R.; Bangledorf, Catherine R.; Rieder, Robert G.

    1992-03-01

    The US Army has a need to develop topical protectants that can decrease the effects of cutaneous exposure to chemical warfare (CW) agents. Such materials would enhance a soldier's ability to carry out the mission in a chemically hostile environment, would lessen the burden on medical personnel, and may allow the casualties to return to duty in a shorter period of time than might otherwise be possible. In a preliminary report (E. H. Braue, Jr. and M. G. Pannella, Applied Spectrosc., 44, 1061 (1990)), we described a unique analytical method using FT-IR spectroscopy and the horizontal attenuated total reflectance (ATR) accessory for evaluating the effectiveness of topical skin protectants (TSPs) against penetration by chemical agents. We now describe the application of this method to the chemical warfare agent sulfur mustard (HD).

  18. Total reflection X-ray fluorescence trace mercury determination by trapping complexation: Application in advanced oxidation technologies

    NASA Astrophysics Data System (ADS)

    Custo, Graciela; Litter, Marta I.; Rodrguez, Diana; Vzquez, Cristina

    2006-11-01

    It is well known that Hg species cause high noxious effects on the health of living organisms even at very low levels (5 ?g/L). Quantification of this element is an analytical challenge due to the peculiar physicochemical properties of all Hg species. The regulation of the maximal allowable Hg concentration led to search for sensitive methods for its determination. Total reflection X-ray fluorescence is a proved instrumental analytical tool for the determination of trace elements. In this work, the use of total reflection X-ray fluorescence for Hg quantification is investigated. However, experimental determination by total reflection X-ray fluorescence requires depositing a small volume of sample on the reflector and evaporation of the solvent until dryness to form a thin film. Because of volatilization of several Hg forms, a procedure to capture these volatile species in liquid samples by using complexing agents is proposed. Acetate, oxalic acid, ethylenediaminetetracetic acid and ammonium pyrrolidine-dithiocarbamate were assayed for trapping the analytes into the solution during the preparation of the sample and onto the reflector during total reflection X-ray fluorescence measurements. The proposed method was applied to evaluate Hg concentration during TiO 2-heterogeneous photocatalysis, one of the most known advanced oxidation technologies. Advanced oxidation technologies are processes for the treatment of effluents in waters and air that involve the generation of very active oxidative and reductive species. In heterogeneous photocatalysis, Hg is transformed to several species under ultraviolet illumination in the presence of titanium dioxide. Total reflection X-ray fluorescence was demonstrated to be applicable in following the extent of the heterogeneous photocatalysis reaction by determining non-transformed Hg in the remaining solution.

  19. Analysis of moisture content, total oil and fatty acid composition by NIR reflectance spectroscopy: a review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near Infrared (NIR) Reflectance spectroscopy has established itself as an important analytical technique in the field of food and agriculture. It is quicker and easier to use and does not require processing the samples with corrosive chemicals such as acids or hydroxides. However, for a long time t...

  20. Analysis of Total Oil and Fatty Acids Composition by Near Infrared Reflectance Spectroscopy in Edible Nuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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-edib...

  1. Modeling changes in the hemoglobin concentration of skin with total diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Glennie, Diana L.; Hayward, Joseph E.; Farrell, Thomas J.

    2015-03-01

    The ability to monitor changes in the concentration of hemoglobin in the blood of the skin in real time is a key component to personalized patient care. Since hemoglobin has a unique absorption spectrum in the visible light range, diffuse reflectance spectroscopy is the most common approach. Although the collection of the diffuse reflectance spectrum with an integrating sphere (IS) has several calibration challenges, this collection method is sufficiently user-friendly that it may be worth overcoming the initial difficulty. Once the spectrum is obtained, it is commonly interpreted with a log-inverse-reflectance (LIR) or "absorbance" analysis that can only accurately monitor changes in the hemoglobin concentration when there are no changes to the nonhemoglobin chromophore concentrations which is not always the case. We address the difficulties associated with collection of the diffuse reflectance spectrum with an IS and propose a model capable of retrieving relative changes in hemoglobin concentration from the visible light spectrum. The model is capable of accounting for concentration changes in the nonhemoglobin chromophores and is first characterized with theoretical spectra and liquid phantoms. The model is then used in comparison with a common LIR analysis on temporal measurements from blanched and reddened human skin.

  2. Critical coupling layer thickness for positive or negative Goos-Hänchen shifts near the excitation of backward surface polaritons in Otto-ATR systems

    NASA Astrophysics Data System (ADS)

    Zeller, Mariana A.; Cuevas, Mauro; Depine, Ricardo A.

    2015-05-01

    We present a theoretical analysis of the lateral displacement (Goos-Hänchen shift) of spatially limited beams reflected from attenuated total reflection (ATR) devices in the Otto configuration when backward surface plasmon polaritons are excited at the interface between a positive refractive index slab and a semi-infinite metamaterial with a negative refractive index. First, the stationary phase approximation and a phenomenological model based on the properties of the complex poles and zeroes of the reflection coefficient are used to demonstrate that: (i) the excitation of backward surface waves can lead to both negative and positive (and not exclusively negative) Goos-Hänchen shifts, and (ii) the sign of the shift depends on whether the value of the coupling layer thickness is higher or lower than a critical value characteristic of the ATR structure. Then, these findings are verified through rigorous calculations of the spatial structure of the reflected beam. For incident beams with a Gaussian profile, the lateral shift calculated as the first moment of the field distribution of the reflected beam agrees quite well with the predictions of approximate analysis. Near the resonant excitation of the backward surface plasmon polariton, large (negative or positive) Goos-Hänchen shifts are obtained, along with a splitting of the reflected beam.

  3. Glancing Angle Dependence of the X-Ray Emission Measured under Total Reflection Angle X-Ray Spectroscopy (TRAXS) Condition during Reflection High Energy Electron Diffraction Observation

    NASA Astrophysics Data System (ADS)

    Yamanaka, Toshiro; Hanada, Takashi; Ino, Shozo; Daimon, Hiroshi

    1992-10-01

    We measured the glancing angle (?g) dependence of the X-ray emission from Si(111)-\\sqrt{3}\\sqrt{3}-Ag and ?-\\sqrt{3}\\sqrt{3}-Au surfaces during Reflection High Energy Electron Diffraction observation under the Total Reflection Angle X-ray Spectroscopy condition. The characteristic X-rays AgL and AuM decreased according to 1/sin ?g. The function 1/\\sin?g is easily understood in terms of Ag and Au atoms located at the top layer of the surface. The SiK and the bremsstrahlung showed broad peaks around 8. These trends of the curves are explained by an analysis using Monte Carlo electron trajectory simulation. By measuring the glancing angle dependence we can easily distinguish whether or not a specific kind of atom is confined at the top layer of the surface.

  4. ATM and ATR signaling at a glance.

    PubMed

    Awasthi, Poorwa; Foiani, Marco; Kumar, Amit

    2015-12-01

    ATM and ATR signaling pathways are well conserved throughout evolution and are central to the maintenance of genome integrity. Although the role of both ATM and ATR in DNA repair, cell cycle regulation and apoptosis have been well studied, both still remain in the focus of current research activities owing to their role in cancer. Recent advances in the field suggest that these proteins have an additional function in maintaining cellular homeostasis under both stressed and non-stressed conditions. In this Cell Science at a Glance article and the accompanying poster, we present an overview of recent advances in ATR and ATM research with emphasis on that into the modes of ATM and ATR activation, the different signaling pathways they participate in - including those that do not involve DNA damage - and highlight their relevance in cancer. PMID:26567218

  5. 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.

  6. An Evaluation of Total Solar Reflectance and Spectral Band Ratioing Techniques for Estimating Soil Water Content

    NASA Technical Reports Server (NTRS)

    Reginato, R. J.; Vedder, J. F.; Idso, S. B.; Jackson, R. D.; Blanchard, M. B.; Goettelman, R.

    1977-01-01

    For several days in March of 1975, reflected solar radiation measurements were obtained from smooth and rough surfaces of wet, drying, and continually dry Avondale loam at Phoenix, Arizona, with pyranometers located 50 cm above the ground surface and a multispectral scanner flown at a 300-m height. The simple summation of the different band radiances measured by the multispectral scanner proved equally as good as the pyranometer data for estimating surface soil water content if the multispectral scanner data were standardized with respect to the intensity of incoming solar radiation or the reflected radiance from a reference surface, such as the continually dry soil. Without this means of standardization, multispectral scanner data are most useful in a spectral band ratioing context. Our results indicated that, for the bands used, no significant information on soil water content could be obtained by band ratioing. Thus the variability in soil water content should insignificantly affect soil-type discrimination based on identification of type-specific spectral signatures. Therefore remote sensing, conducted in the 0.4- to 1.0-micron wavelength region of the solar spectrum, would seem to be much More suited to identifying crop and soil types than to estimating of soil water content.

  7. Approximate analytical solution for waveguide excitation of a plane dielectric layer by a Gaussian beam at frustrated total internal reflection.

    PubMed

    Serdyuk, Vladimir; Rudnitsky, Anton

    2015-05-01

    We present an approximate 2D asymptotic analytic theory of light field excitation in a plane thin dielectric layer under conditions of frustrated total internal reflection, when an inclined Gaussian beam, falling from a triangular prism, excites a decaying field in air spacing between a prism and a plane dielectric. Ignoring the radiation scattering on the sharp edges of a prism, we have obtained the formulas that allow us to compute spatial structures of an electromagnetic field in every point of space and to estimate the integral efficiency of waveguide mode excitation in a plane dielectric layer and the total energy of a reflected beam. It is shown that the width of an initial Gaussian beam has an effect on waveguide mode intensity. PMID:26366908

  8. 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

    2014-10-01

    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. PMID:25203613

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  10. High Refractive Index Silicone Gels for Simultaneous Total Internal Reflection Fluorescence and Traction Force Microscopy of Adherent Cells

    PubMed Central

    Besser, Achim; Sundd, Prithu; Ley, Klaus; Danuser, Gaudenz; Ginsberg, Mark H.; Groisman, Alex

    2011-01-01

    Substrate rigidity profoundly impacts cellular behaviors such as migration, gene expression, and cell fate. Total Internal Reflection Fluorescence (TIRF) microscopy enables selective visualization of the dynamics of substrate adhesions, vesicle trafficking, and biochemical signaling at the cell-substrate interface. Here we apply high-refractive-index silicone gels to perform TIRF microscopy on substrates with a wide range of physiological elastic moduli and simultaneously measure traction forces exerted by cells on the substrate. PMID:21961031

  11. Application of Variable Angle Total Internal Reflection Fluorescence Microscopy to Investigate Protein Dynamics in Intact Plant Cells.

    PubMed

    Wan, Yinglang; Xue, Yiqun; Li, Ruili; Lin, Jinxing

    2016-01-01

    Variable angle total internal reflection fluorescence microscopy (VA-TIRFM) is an optical method to observe the molecular events occurring in an extremely thin region near the plasma membrane. Recently, the VA-TIRFM technique has been widely used to study fluorescently labeled target molecules in living animal and plant cells. Here, we describe the optical principle of the VA-TIRFM technique and provide a detailed experimental procedure for the study of living plant cells. PMID:26577785

  12. Mobile target ladar ATR system

    NASA Astrophysics Data System (ADS)

    Hodge, Jesse L.; DeKruger, David H.; Park, Alden E.

    2001-10-01

    The Mobile Target Acquisition System (MTAS) is an automatic target recognition (ATR) system developed by the Naval Air Warfare Center Weapons Division, China Lake, CA, under funding by the Office of Naval Research (ONR) to detect and identify mobile target laser detection and ranging (LADAR) range signatures. The primary objective was to achieve high correct system identification rates for range signatures of relatively low numbers of pixels on target and, at the same time, maintain a low system identification false alarm rate. MTAS met this objective by stressing conservation and efficient exploitation of target information at all levels of processing. Adaptive noise cleaning conserves target information by filtering pixels only when the pixel and its neighbors satisfied the criteria for range dropouts. The MTAS detector holds false alarms to a low level by convolving synthetic templates with the gradient of the range image and fusing the resulting correlation surface with a blob size filter. Mobile target identification fuses 2-D silhouette shape with 3-D (21/2-D) volumetric shape where the mixture of 2- and 3-D shapes is controlled by a single parameter. The match between the measured LADAR range signature and the synthetic range template efficiently and effectively exploits scarce target information by including all target and template pixels in the Fuzzy Tanimoto Distance similarity measure. This system has successfully detected and identified measured mobile LADAR target signatures with 200 pixels on target and greater with a low confuser identification rate and no system clutter identification false alarms.

  13. Two-dimensional standing wave total internal reflection fluorescence microscopy: superresolution imaging of single molecular and biological specimens.

    PubMed

    Chung, Euiheon; Kim, Daekeun; Cui, Yan; Kim, Yang-Hyo; So, Peter T C

    2007-09-01

    The development of high resolution, high speed imaging techniques allows the study of dynamical processes in biological systems. Lateral resolution improvement of up to a factor of 2 has been achieved using structured illumination. In a total internal reflection fluorescence microscope, an evanescence excitation field is formed as light is total internally reflected at an interface between a high and a low index medium. The <100 nm penetration depth of evanescence field ensures a thin excitation region resulting in low background fluorescence. We present even higher resolution wide-field biological imaging by use of standing wave total internal reflection fluorescence (SW-TIRF). Evanescent standing wave (SW) illumination is used to generate a sinusoidal high spatial frequency fringe pattern on specimen for lateral resolution enhancement. To prevent thermal drift of the SW, novel detection and estimation of the SW phase with real-time feedback control is devised for the stabilization and control of the fringe phase. SW-TIRF is a wide-field superresolution technique with resolution better than a fifth of emission wavelength or approximately 100 nm lateral resolution. We demonstrate the performance of the SW-TIRF microscopy using one- and two-directional SW illumination with a biological sample of cellular actin cytoskeleton of mouse fibroblast cells as well as single semiconductor nanocrystal molecules. The results confirm the superior resolution of SW-TIRF in addition to the merit of a high signal/background ratio from TIRF microscopy. PMID:17483188

  14. Two-Dimensional Standing Wave Total Internal Reflection Fluorescence Microscopy: Superresolution Imaging of Single Molecular and Biological Specimens

    PubMed Central

    Chung, Euiheon; Kim, Daekeun; Cui, Yan; Kim, Yang-Hyo; So, Peter T. C.

    2007-01-01

    The development of high resolution, high speed imaging techniques allows the study of dynamical processes in biological systems. Lateral resolution improvement of up to a factor of 2 has been achieved using structured illumination. In a total internal reflection fluorescence microscope, an evanescence excitation field is formed as light is total internally reflected at an interface between a high and a low index medium. The <100 nm penetration depth of evanescence field ensures a thin excitation region resulting in low background fluorescence. We present even higher resolution wide-field biological imaging by use of standing wave total internal reflection fluorescence (SW-TIRF). Evanescent standing wave (SW) illumination is used to generate a sinusoidal high spatial frequency fringe pattern on specimen for lateral resolution enhancement. To prevent thermal drift of the SW, novel detection and estimation of the SW phase with real-time feedback control is devised for the stabilization and control of the fringe phase. SW-TIRF is a wide-field superresolution technique with resolution better than a fifth of emission wavelength or ?100 nm lateral resolution. We demonstrate the performance of the SW-TIRF microscopy using one- and two-directional SW illumination with a biological sample of cellular actin cytoskeleton of mouse fibroblast cells as well as single semiconductor nanocrystal molecules. The results confirm the superior resolution of SW-TIRF in addition to the merit of a high signal/background ratio from TIRF microscopy. PMID:17483188

  15. In-situ monitoring of blood glucose level for dialysis machine by AAA-battery-size ATR Fourier spectroscopy

    NASA Astrophysics Data System (ADS)

    Hosono, Satsuki; Sato, Shun; Ishida, Akane; Suzuki, Yo; Inohara, Daichi; Nogo, Kosuke; Abeygunawardhana, Pradeep K.; Suzuki, Satoru; Nishiyama, Akira; Wada, Kenji; Ishimaru, Ichiro

    2015-07-01

    For blood glucose level measurement of dialysis machines, we proposed AAA-battery-size ATR (Attenuated total reflection) Fourier spectroscopy in middle infrared light region. The proposed one-shot Fourier spectroscopic imaging is a near-common path and spatial phase-shift interferometer with high time resolution. Because numerous number of spectral data that is 60 (= camera frame rare e.g. 60[Hz]) multiplied by pixel number could be obtained in 1[sec.], statistical-averaging improvement realize high-accurate spectral measurement. We evaluated the quantitative accuracy of our proposed method for measuring glucose concentration in near-infrared light region with liquid cells. We confirmed that absorbance at 1600[nm] had high correlations with glucose concentrations (correlation coefficient: 0.92). But to measure whole-blood, complex light phenomenon caused from red blood cells, that is scattering and multiple reflection or so, deteriorate spectral data. Thus, we also proposed the ultrasound-assisted spectroscopic imaging that traps particles at standing-wave node. Thus, if ATR prism is oscillated mechanically, anti-node area is generated around evanescent light field on prism surface. By elimination complex light phenomenon of red blood cells, glucose concentration in whole-blood will be quantify with high accuracy. In this report, we successfully trapped red blood cells in normal saline solution with ultrasonic standing wave (frequency: 2[MHz]).

  16. Sensitivity studies for space-based measurement of atmospheric total column carbon dioxide by reflected sunlight.

    PubMed

    Mao, Jianping; Kawa, S Randolph

    2004-02-01

    The feasibility of making space-based carbon dioxide (CO2) measurements for global and regional carbon-cycle studies is explored. With the proposed detection method, we use absorption of reflected sunlight near 1.58 microm. The results indicate that the small (degrees 1%) changes in CO2 near the Earth's surface are detectable provided that an adequate sensor signal-to-noise ratio and spectral resolution are achievable. Modification of the sunlight path by scattering of aerosols and cirrus clouds could, however, lead to systematic errors in the CO2 column retrieval; therefore ancillary aerosol and cloud data are important to reduce errors. Precise measurement of surface pressure and good knowledge of the atmospheric temperature profile are also required. PMID:14960086

  17. Comparison of HEU and LEU Fuel Neutron Spectrum for ATR Fuel Element and ATR Flux-Trap Positions

    SciTech Connect

    G. S. Chang

    2008-10-01

    The Advanced Test Reactor (ATR) is a high power and high neutron flux research reactor operating in the United States. Powered with highly enriched uranium (HEU), the ATR has a maximum thermal power rating of 250 MWth. Because of the high total core power and high neutron flux, the ATR is an ideal candidate for assessing the feasibility of converting an HEU driven reactor to a low-enriched core. An optimized low-enriched uranium (LEU) (U-10Mo) core conversion case, which can meet the project requirements, has been selected. However, LEU contains a significant quantity of high density U-238 (80.3 wt.%), which will harden the neutron spectrum in the core region. Based on the reference ATR HEU and the optimized LEU full core plate-by-plate (PBP) models, the present work investigates and compares the neutron spectra differences in the fuel element (FE), Northeast flux trap (NEFT), Southeast flux trap (SEFT), and East flux trap (EFT) positions. A detailed PBP MCNP ATR core model was developed and validated for fuel cycle burnup comparison analysis. The current ATR core with HEU U 235 enrichment of 93.0wt.% was used as the reference model. Each HEU fuel element contains 19 fuel plates with a fuel meat thickness of 0.508 mm (20 mil). In this work, an optimized LEU (U-10Mo) core conversion case with a nominal fuel meat thickness of 0.330 mm (13 mil) and the U-235 enrichment of 19.7 wt.% was used to calculate the impact of the neutron spectrum in FE and FT positions. MCNP-calculated results show that the neutron spectrum in the LEU FE is slightly harder than in the HEU FE, as expected. However, when neutrons transport through water coolant and beryllium (Be), the neutrons are thermalized to an equilibrium neutron spectrum as a function of water volume fraction in the investigated FT positions. As a result, the neutron spectrum differences of the HEU and LEU in the NEFT, SEFT, and EFT are negligible. To demonstrate that the LEU core fuel cycle performance can meet the Updated Final Safety Analysis Report (UFSAR) safety requirements, additional studies will be necessary to evaluate and compare safety parameters such as void reactivity and Doppler coefficients, control components worth (outer shim control cylinders, safety rods and regulating rod), and shutdown margins between the HEU and LEU cores.

  18. Dielectric compound parabolic concentrating solar collector with frustrated total internal reflection absorber

    NASA Astrophysics Data System (ADS)

    Hull, J. R.

    Since its introduction, the concept of nonimaging solar concentrators, as exemplified by the compound parabolic concentrator (CPC) design, has greatly enhanced the ability to collect solar energy efficiently in thermal and photovoltaic devices. When used as a primary concentrator, a CPC can provide significant concentration without the complication of a tracking mechanism and its associated maintenance problems. When used as a secondary, a CPC provides higher total concentration, or for a fixed concentration, tolerates greater tracking error in the primary.

  19. 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 ? = 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 ? = 0.2, 0.3 eV. This work was supported by SESIC Mexico, Promep Grant FOFM-2008 and by CONACyT, Mexico.

  20. Formation of Assemblies Comprising RuPolypyridine Complexes and CdSe Nanocrystals Studied by ATR-FTIR Spectroscopy and DFT Modeling

    SciTech Connect

    Koposov, Alexey Y.; Cardolaccia, Thomas; Albert, Victor; Badaeva, Ekaterina; Kilina, Svetlana; Meyer, Thomas J.; Tretiak, Sergei; Sykora, Milan

    2011-07-05

    The interaction between CdSe nanocrystals (NCs) passivated with trioctylphosphine oxide (TOPO) ligands and a series of Rupolypyridine complexes was studied by attenuated total reflectance FTIR (ATR-FTIR) and modeled using density functional theory (DFT). The results of DFT modeling are consistent with the experiment, showing that for the deprotonated carboxylic acid group the coupling to two Cd atoms via a bridging mode is the energetically most favorable mode of attachment for all nonequivalent NC surface sites and that the attachment of the protonated carboxylic acid is thermodynamically significantly less favorable.

  1. Nonlinear absorbance amplification using a diffuse reflectance cell: total organic carbon monitoring at 214 nm.

    PubMed

    Li, Yin-Huan; Shelor, C Phillip; Dasgupta, Purnendu K

    2015-01-20

    We present an absorption spectrometric method using a polytetrafluoroethylene (PTFE) cell as a diffuse reflector. The system was used for monitoring ultrapure water. All compounds absorb to some degree at low UV wavelengths, and the absorption at 214 nm from a zinc lamp source was monitored using a charge-coupled device (CCD) spectrometer. The absorption was interpreted in terms of total organic carbon present. The cell acts as a nonlinear absorbance amplifier, improving both the limit of detection (LOD) and the dynamic range. Potassium hydrogen phthalate (KHP) and glucose were used to evaluate the system and provided respective LODs of 46.5 ng/L and 4.5 mg/L as carbon. Although the physical path length was 25 cm, a maximum effective path length of 280 cm was observed at the lowest tested KHP concentrations. The system is intended for real-time monitoring of ultrapure water. PMID:25514042

  2. Selective detection of the structural changes upon photoreactions of several redox cofactors in photosystem II by means of light-induced ATR-FTIR difference spectroscopy

    NASA Astrophysics Data System (ADS)

    Okubo, Tatsunori; Noguchi, Takumi

    2007-04-01

    Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was applied for the first time to detect the structural changes upon photoreactions of redox cofactors in photosystem II (PSII). The PSII-enriched membranes from spinach were adsorbed on the surface of a silicon prism, and FTIR measurements of various redox cofactors were performed for the same sample but under different conditions by exchanging buffers in a flow cell. Light-induced FTIR difference spectra upon redox reactions of the oxygen-evolving Mn cluster, the primary quinone electron acceptor Q A, the redox-active tyrosine Y D, the primary electron acceptor pheophytin, and the primary electron donor chlorophyll P680 were successively recorded in buffers including different redox reagents and inhibitors. All of these cofactors remained active in the PSII membranes on the silicon surface, and the resultant spectra were basically identical to those previously recorded by the conventional transmission method. These ATR-FTIR measurements enable accurate comparison between reactions of different active sites in a single PSII sample. The present results demonstrated that the ATR-FTIR spectroscopy is a useful technique for investigation of the reaction mechanism of PSII.

  3. Quantum (not frustrated) theory of the total internal reflection as the source of the Goos-Hnchen shift

    NASA Astrophysics Data System (ADS)

    Jakiel, Jacek; Kantor, Wies?aw

    2014-10-01

    The frustrated total internal reflection theories (FTIR) from previous century are thoroughly recalculated from the, so called, monodromy operator's point of view - a theory lunched by Born and Wolf [Principles of Optics (Pergamon Press, 1975), Chap. 1.6] and Arnold [Geometric Methods in the Theory of Ordinary Differential Equations (Springer, 1987)]. Monodromy is a theory of simultaneous solution (for both reflection and transmission amplitudes) of one dimensional Schrdinger equation (for the wavefunction and its derivative) and the Maxwell equation (for electric and magnetic fields). Introducing new quantities: the dwell distance and the phase distance, we get general Goos-Hnchen (G-H) shift formula for optical tunneling for three layer system with refraction indexes n0, n1, n2. This formula reduces itself to expressions known from the scientific literature for infinite air gap (infinite width of second layer). Extension to many layers is possible.

  4. 77 FR 67557 - Special Conditions: ATR-GIE Avions de Transport Regional, Models ATR42-500 and ATR72-212A...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-13

    ... Privacy Act Statement can be found in the Federal Register published on April 11, 2000 (65 FR 19477-19478... Federal Aviation Administration 14 CFR Part 25 Special Conditions: ATR-GIE Avions de Transport Regional, Models ATR42-500 and ATR72-212A Airplanes; Aircraft Electronic System Security Protection...

  5. 76 FR 47520 - Airworthiness Directives; ATR-GIE Avions de Transport Régional Model ATR42 and ATR72 Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-05

    ... continued.airworthiness@atr.fr ; Internet http://www.aerochain.com . You may review copies of the referenced... 12866; 2. Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034... Transport R gional Model ATR42 and ATR72 Airplanes AGENCY: Federal Aviation Administration (FAA),...

  6. Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico

    NASA Astrophysics Data System (ADS)

    Martinez, T.; Lartigue, J.; Zarazua, G.; Avila-Perez, P.; Navarrete, M.; Tejeda, S.

    2010-06-01

    Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO 3 and H 2O 2 (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different ( α = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 μg g - 1 . A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of "Citrus Leaves" and a blank were treated in the same way.

  7. Design of an efficient Fresnel-type lens utilizing double total internal reflection for solar energy collection.

    PubMed

    Wallhead, Ian; Jimnez, Teresa Molina; Ortiz, Jose Vicente Garca; Toledo, Ignacio Gonzalez; Toledo, Cristbal Gonzalez

    2012-11-01

    A novel of Fresnel-type lens for use as a solar collector has been designed which utilizes double total internal reflection (D-TIR) to optimize collection efficiency for high numerical aperture lenses (in the region of 0.3 to 0.6 NA). Results show that, depending on the numerical aperture and the size of the receiver, a collection efficiency theoretical improvement on the order of 20% can be expected with this new design compared with that of a conventional Fresnel lens. PMID:23326849

  8. Design of an efficient Fresnel-type lens utilizing double total internal reflection for solar energy collection.

    PubMed

    Wallhead, Ian; Jimnez, Teresa Molina; Ortiz, Jose Vicente Garca; Toledo, Ignacio Gonzalez; Toledo, Cristbal Gonzalez

    2012-11-01

    A novel of Fresnel-type lens for use as a solar collector has been designed which utilizes double total internal reflection (D-TIR) to optimize collection efficiency for high numerical aperture lenses (in the region of 0.3 to 0.6 NA). Results show that, depending on the numerical aperture and the size of the receiver, a collection efficiency theoretical improvement on the order of 20% can be expected with this new design compared with that of a conventional Fresnel lens. PMID:23187651

  9. An antidot array as an edge for total non-reflection of spin waves in yttrium iron garnet films

    NASA Astrophysics Data System (ADS)

    Gieniusz, R.; Bessonov, V. D.; Guzowska, U.; Stognii, A. I.; Maziewski, A.

    2014-02-01

    An array of antidots has been used as an edge to create the phenomenon of total non-reflection of spin waves in yttrium iron garnet films. At the critical angle between the line of antidots and the magnetic field, we observe a high-intensity beam of spin waves moving along the line of antidots. The properties of these waves are investigated experimentally by Brillouin light scattering spectroscopy. The conditions required for the occurrence of this phenomenon based on an analysis of the properties of the isofrequency dependencies are presented. The numerical simulations are in good agreement with those of the experimental measurements.

  10. Multiplex detection of histone-modifying enzymes by total internal reflection fluorescence-based single-molecule detection.

    PubMed

    Ma, Fei; Liu, Meng; Wang, Zi-Yue; Zhang, Chun-Yang

    2016-01-01

    We develop a sensitive and selective method for the multiplex detection of histone-modifying enzymes (HMEs) through the integration of antibody-based fluorescence labeling with total internal reflection fluorescence (TIRF)-based single-molecule detection. This method exhibits excellent specificity and high sensitivity with a detection limit of 21 pM for histone acetyltransferase GcN5 and 12 pM for histone methyltransferase G9a, and it can be applied for the screening of HME inhibitors as well. PMID:26608941

  11. Three-Dimensional Orientation Determination of Stationary Anisotropic Nanoparticles with Sub-Degree Precision under Total Internal Reflection Scattering Microscopy

    SciTech Connect

    Marchuk, Kyle; Fang, Ning

    2013-11-13

    Single-particle and single-molecule orientation determination plays a vital role in deciphering nanoscale motion in complex environments. Previous attempts to determine the absolute three-dimensional orientation of anisotropic particles rely on subjective pattern matching and are inherently plagued by high degrees of uncertainty. Herein, we describe a method utilizing total internal reflection scattering microscopy to determine the 3D orientation of gold nanorods with subdegree uncertainty. The method is then applied to the biologically relevant system of microtubule cargo loading. Finally, we demonstrate the method holds potential for identifying single particles versus proximate neighbors within the diffraction limited area.

  12. An antidot array as an edge for total non-reflection of spin waves in yttrium iron garnet films

    SciTech Connect

    Gieniusz, R. Guzowska, U.; Maziewski, A.; Bessonov, V. D.; Stognii, A. I.

    2014-02-24

    An array of antidots has been used as an edge to create the phenomenon of total non-reflection of spin waves in yttrium iron garnet films. At the critical angle between the line of antidots and the magnetic field, we observe a high-intensity beam of spin waves moving along the line of antidots. The properties of these waves are investigated experimentally by Brillouin light scattering spectroscopy. The conditions required for the occurrence of this phenomenon based on an analysis of the properties of the isofrequency dependencies are presented. The numerical simulations are in good agreement with those of the experimental measurements.

  13. A New Method for Axial Decay Function Calibration of Evanescent Field in Multi-Angle Total Internal Reflection Fluorescence Microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Xiu, Peng; Jin, Luhong; Nan, Di; Kuang, Cuifang; Zheng, Xiaoxiang; Xu, Yingke; Liu, Xu

    2016-01-01

    Three-dimensional image reconstruction in multi-angle total internal reflection fluorescence microscopy relies on actual penetration depths of evanescent wave at various incidence angles. In this paper, we propose a simple and elegant calibration method to calculate the actual axial decay profile of a given evanescent field, for the analytical solution of theoretical equation is hard to solve in complicated conditions. The results calculated by the proposed method agree with the experimental demands in our research. Our calibration method, together with multi-angle TIRF imaging, permits 3D reconstruction of cell surface in superb axial resolution.

  14. 45 polymer-based total internal reflection coupling mirrors for fully embedded intraboard guided wave optical interconnects

    NASA Astrophysics Data System (ADS)

    Wang, Li; Wang, Xiaolong; Jiang, Wei; Choi, Jinho; Bi, Hai; Chen, Ray

    2005-10-01

    An array of 50?m50?m polymer waveguides with 45 total internal reflection (TIR) wideband coupling mirrors were fabricated by soft molding to achieve fully embedded boardlevel optoelectronic interconnects. The 45 TIR coupling mirrors were formed at the ends of the waveguides to provide surface normal light coupling between waveguides and optoelectronic devices. Three-dimensional optoelectronic interconnects were replicated in one-step transfer by the soft molding technique. The measured propagation loss of the multimode waveguide was 0.16dB/cm at 850nm wavelength. The coupling efficiency of the silver-coated 45 micromirrors buried under the top cladding was 92% with low polarization sensitivity.

  15. High accuracy subwavelength distance measurements: A variable-angle standing-wave total-internal-reflection optical microscope

    SciTech Connect

    Haynie, A.; Min, T.-J.; Luan, L.; Mu, W.; Ketterson, J. B.

    2009-04-15

    We describe an extension of the total-internal-reflection microscopy technique that permits direct in-plane distance measurements with high accuracy (<10 nm) over a wide range of separations. This high position accuracy arises from the creation of a standing evanescent wave and the ability to sweep the nodal positions (intensity minima of the standing wave) in a controlled manner via both the incident angle and the relative phase of the incoming laser beams. Some control over the vertical resolution is available through the ability to scan the incoming angle and with it the evanescent penetration depth.

  16. Evolution of radar reflectivity and total lightning characteristics of the 21 April 2006 mesoscale convective system over Texas

    NASA Astrophysics Data System (ADS)

    Hodapp, Charles L.; Carey, Lawrence D.; Orville, Richard E.

    2008-07-01

    On 21 April 2006 a mesoscale convective system (MCS) passed within range of the Houston (KHGX) operational Weather Surveillance Radar 1988 Doppler (WSR-88D, S-band) and the Houston Lightning Detection and Ranging (LDAR) network, which measures the time and three-dimensional location of total, or both intracloud (IC) and cloud-to-ground (CG), lightning. This study documents the evolution of total lightning and radar reflectivity for the 21 April 2006 MCS over Texas, with emphasis on the stratiform region and those processes in the convection region that likely influence stratiform region development. As the MCS traverses the LDAR network, the system slowly matures with a weakening convective line and a developing stratiform region and radar bright band. The area of stratiform precipitation increases by an order of magnitude and mean stratiform radar reflectivity increases by 7-8 dB in the radar bright band and mixed-phase zone (0 to - 10 C) just above it. As the stratiform region matures, the total lightning pathway slopes rearward and downward from the back of the convective line and into the stratiform region. At early times, the pathway extends horizontally rearward 40 to 50 km into the stratiform region at an altitude of 10 to 12 km. Near the end of the analysis time period, the total lightning pathway slopes rearward 40 km and downward 6 km through the transition zone before extending 40 to 50 km in the stratiform region at an altitude of 5 to 7 km. The sloping pathway likely results from charged ice particles advected from the convective line by storm relative front to rear flow while the level pathway extending further into the stratiform region is likely caused by both charge advection and local in-situ charging. As the stratiform region matures, the stratiform region total lightning flash rate increases and total lightning heights decrease. The percentage of stratiform total lightning flashes originating in the stratiform region increases significantly from 10% to 45%. The number of positive CG flashes in the stratiform region also increases with 73% originating in the convective or transition regions. Both in-situ charging mechanisms created by the development of the mesoscale updraft and charge advection by the front to rear flow likely contribute to the increased electrification and total lightning production of the stratiform region.

  17. Screening a random mutagenesis library of a fungal ?-fructofuranosidase using FT-MIR ATR spectroscopy and multivariate analysis.

    PubMed

    Trollope, K M; Nieuwoudt, H H; Grgens, J F; Volschenk, H

    2014-05-01

    Short-chain fructooligosaccharides (scFOS) are valuable health-promoting food additives. During the batch production of scFOS from sucrose the ?-fructofuranosidase catalyst is subject to product inhibition by glucose. Engineering the enzyme for reduced sensitivity to glucose could improve product yields or process productivity while preserving the simple industrial batch design. Random mutagenesis is a useful technique for engineering proteins but should be coupled to a relevant high-throughput screen. Such a screen for sucrose and scFOS quantification remains elusive. This work presents the development of a screening method displaying potential high-throughput capacity for the evaluation of ?-fructofuranosidase libraries using Fourier transform mid-infrared attenuated total reflectance (FT-MIR ATR) spectroscopy and multivariate analysis. A calibration model for the quantification of sucrose in enzyme assay samples ranged from 5 to 200g/l and the standard error of prediction was below 13g/l. A library of the Aspergillus japonicus fopA gene was generated by error prone PCR and screened in Saccharomyces cerevisiae. Using FT-MIR ATR spectroscopy, potential hits were identified as those variants that converted more sucrose in the presence of the glucose inhibitor than the parent. Subsequent analysis of reaction products generated by top performers using high-performance liquid chromatography identified a variant producing higher scFOS levels than the parent. At the peak difference in performance the variant produced 28% more scFOS from the same amount of sucrose. This study highlights the application of FT-MIR ATR spectroscopy to a variant discovery pipeline in the directed evolution of a ?-fructofuranosidase for enhanced scFOS production. PMID:24323289

  18. ATR-FTIR spectroscopy coupled with chemometric analysis discriminates normal, borderline and malignant ovarian tissue: classifying subtypes of human cancer.

    PubMed

    Theophilou, Georgios; Lima, Kssio M G; Martin-Hirsch, Pierre L; Stringfellow, Helen F; Martin, Francis L

    2016-01-01

    Surgical management of ovarian tumours largely depends on their histo-pathological diagnosis. Currently, screening for ovarian malignancy with tumour markers in conjunction with radiological investigations has a low specificity for discriminating benign from malignant tumours. Also, pre-operative biopsy of ovarian masses increases the risk of intra-peritoneal dissemination of malignancy. Intra-operative frozen section, although sufficiently accurate in differentiating tumours according to their histological type, increases operation times. This results in increased surgery-related risks to the patient and additional burden to resource allocation. We set out to determine whether attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, combined with chemometric analysis can be applied to discriminate between normal, borderline and malignant ovarian tumours and classify ovarian carcinoma subtypes according to the unique spectral signatures of their molecular composition. Formalin-fixed, paraffin-embedded ovarian tissue blocks were de-waxed, mounted on Low-E slides and desiccated before being analysed using ATR-FTIR spectroscopy. Chemometric analysis in the form of principal component analysis (PCA), successive projection algorithm (SPA) and genetic algorithm (GA), followed by linear discriminant analysis (LDA) of the obtained spectra revealed clear segregation between benign versus borderline versus malignant tumours as well as segregation between different histological tumour subtypes, when these approaches are used in combination. ATR-FTIR spectroscopy coupled with chemometric analysis has the potential to provide a novel diagnostic approach in the accurate diagnosis of ovarian tumours assisting surgical decision making to avoid under-treatment or over-treatment, with minimal impact to the patient. PMID:26090781

  19. A dynamic thermal ATR-FTIR/chemometric approach to the analysis of polymorphic interconversions. Cimetidine as a model drug.

    PubMed

    Calvo, Natalia L; Maggio, Rubn M; Kaufman, Teodoro S

    2014-04-01

    Crystal polymorphism of active ingredients is relevant to the pharmaceutical industry, since polymorphic changes taking place during manufacture or storage of pharmaceutical formulations can affect critical properties of the products. Cimetidine (CIM) has several relevant solid state forms, including four polymorphs (A, B, C and D), an amorphous form (AM) and a monohydrate (M1). Dehydration of M1 has been reported to yield mixtures of polymorphs A, B and C or just a single form. Standards of the solid forms of CIM were prepared and unequivocally characterized by FTIR spectroscopy, digital microscopy, differential scanning calorimetry and solid state (13)C NMR spectroscopy. Multivariate curve resolution with alternating least squares (MCR-ALS) was coupled to variable temperature attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to dynamically characterize the behavior of form M1 of CIM over a temperature range from ambient to 160C, without sample pretreatment. MCR-ALS analysis of ATR-FTIR spectra obtained from the tested solid under variable temperature conditions unveiled the pure spectra of the species involved in the polymorphic transitions. This allowed the simultaneous observation of thermochemical and thermophysical events associated to the changes involved in the solid forms, enabling their unequivocal identification and improving the understanding of their thermal behavior. It was demonstrated that under the experimental conditions, dehydration of M1 initially results in the formation of polymorph B; after melting and upon cooling, the latter yields an amorphous solid (AM). It was concluded that the ATR-FTIR/MCR association is a promising and useful technique for monitoring solid-state phase transformations. PMID:24509287

  20. Cascaded automatic target recognition (Cascaded ATR)

    NASA Astrophysics Data System (ADS)

    Walls, Bradley

    2010-04-01

    The global war on terror has plunged US and coalition forces into a battle space requiring the continuous adaptation of tactics and technologies to cope with an elusive enemy. As a result, technologies that enhance the intelligence, surveillance, and reconnaissance (ISR) mission making the warfighter more effective are experiencing increased interest. In this paper we show how a new generation of smart cameras built around foveated sensing makes possible a powerful ISR technique termed Cascaded ATR. Foveated sensing is an innovative optical concept in which a single aperture captures two distinct fields of view. In Cascaded ATR, foveated sensing is used to provide a coarse resolution, persistent surveillance, wide field of view (WFOV) detector to accomplish detection level perception. At the same time, within the foveated sensor, these detection locations are passed as a cue to a steerable, high fidelity, narrow field of view (NFOV) detector to perform recognition level perception. Two new ISR mission scenarios, utilizing Cascaded ATR, are proposed.

  1. Live Imaging of Cellular Internalization of Single Colloidal Particle by Combined Label-Free and Fluorescence Total Internal Reflection Microscopy.

    PubMed

    Byrne, Gerard D; Vllasaliu, Driton; Falcone, Franco H; Somekh, Michael G; Stolnik, Snjezana

    2015-11-01

    In this work we utilize the combination of label-free total internal reflection microscopy and total internal reflectance fluorescence (TIRM/TIRF) microscopy to achieve a simultaneous, live imaging of single, label-free colloidal particle endocytosis by individual cells. The TIRM arm of the microscope enables label free imaging of the colloid and cell membrane features, while the TIRF arm images the dynamics of fluorescent-labeled clathrin (protein involved in endocytosis via clathrin pathway), expressed in transfected 3T3 fibroblasts cells. Using a model polymeric colloid and cells with a fluorescently tagged clathrin endocytosis pathway, we demonstrate that wide field TIRM/TIRF coimaging enables live visualization of the process of colloidal particle interaction with the labeled cell structure, which is valuable for discerning the membrane events and route of colloid internalization by the cell. We further show that 500 nm in diameter model polystyrene colloid associates with clathrin, prior to and during its cellular internalization. This association is not apparent with larger, 1 μm in diameter colloids, indicating an upper particle size limit for clathrin-mediated endocytosis. PMID:26402436

  2. Simultaneous multielement determination in vegetable foodstuffs and their respective cell fractions by total-reflection X-ray fluorescence (TXRF).

    PubMed

    Gnther, K; von Bohlen, A

    1990-04-01

    Total-reflection X-ray fluorescence (TXRF) was employed in the multielement determination made on samples of lamb's lettuce and cauliflower as well as in the analysis of their soluble and insoluble cell fractions. All samples were digested with HNO3 and the elements were quantitatively determined with Ga as internal standard. For cell fractionation, the freeze-dried vegetables were mortared in the presence of fine-grain quartz and extracted with a buffer solution; the resulting suspension was then separated by ultracentrifugation into cytosol and pellet components. K, Ca, Mn, Fe, Cu, Zn, Rb and Sr were the elements of which the total content and distribution between cytosol and pellet were determined. As a result of the cellular digestion and extraction procedures employed, greater than or equal to 50% of the total metal contents of Zn, Cu, K and Rb could be reduced to the cytosol phase in both vegetables, however, Sr, Fe, Ca and Mn were mainly bound to the insoluble pellet components which, in the case of cauliflower, contained up to 100% of the total Sr content. As a multielement method, TXRF proved to be an excellent analytical tool in these investigations, since it requires only minute samples with simple preparation and involves a large dynamic measuring scale. PMID:2343677

  3. Study of consumer fireworks post-blast residues by ATR-FTIR.

    PubMed

    Martín-Alberca, Carlos; Zapata, Félix; Carrascosa, Héctor; Ortega-Ojeda, Fernando E; García-Ruiz, Carmen

    2016-03-01

    Specific analytical procedures are requested for the forensic analysis of pre- and post-blast consumer firework samples, which present significant challenges. Up to date, vibrational spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) have not been tested for the analysis of post-blast residues in spite of their interesting strengths for the forensic field. Therefore, this work proposes a simple and fast procedure for the sampling and analysis of consumer firework post-blast residues by a portable FTIR instrument with an Attenuated Total Reflection (ATR) accessory. In addition, the post-blast residues spectra of several consumer fireworks were studied in order to achieve the identification of their original chemical compositions. Hence, this work analysed 22 standard reagents usually employed to make consumer fireworks, or because they are related to their combustion products. Then, 5 different consumer fireworks were exploded, and their residues were sampled with dry cotton swabs and directly analysed by ATR-FTIR. In addition, their pre-blast fuses and charges were also analysed in order to stablish a proper comparison. As a result, the identification of the original chemical compositions of the post-blast samples was obtained. Some of the compounds found were potassium chlorate, barium nitrate, potassium nitrate, potassium perchlorate or charcoal. An additional study involving chemometric tools found that the results might greatly depend on the swab head type used for the sampling, and its sampling efficiency. The proposed procedure could be used as a complementary technique for the analysis of consumer fireworks post-blast residues. PMID:26717839

  4. Investigation of drug release from suspension using FTIR-ATR technique: part II. Determination of dissolution coefficient of drugs.

    PubMed

    Hanh, B D; Neubert, R H; Wartewig, S

    2000-08-25

    Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy was applied to a release experiment in order to determine the dissolution coefficient of drug particles in heterogeneous semisolid formulations. The drug release experiment was carried out using ketoconazole suspended in Vaseline with various amounts of paraffinum liquidum as donor and an artificial dodecanol-collodion (DDC) membrane as acceptor compartment. Monitoring changes in IR bands due to ketoconazole the decrease of the drug content near the ATR crystal ointment was followed as a function of time. A mathematical model based on Fick's second law with a source term was used to derive the apparent dissolution coefficient Kdis by numerical fitting the experimental data. It was found that Kdis is dependent on the fraction of paraffinum liquidum in the suspension. Taking into account all experimental parameters required, the transport process was simulated and discussed in terms of drug concentration- time and drug concentration- distance profiles. Calculating the area under the mass-time curve it was tried to predict the 'dermal bioavailability' in the acceptor (AUCa). PMID:11011999

  5. In situ ATR-IR spectroscopic and electron microscopic analyses of settlement secretions of Undaria pinnatifida kelp spores

    PubMed Central

    Petrone, L.; Easingwood, R.; Barker, M. F.; McQuillan, A. J.

    2011-01-01

    Knowledge about the settlement of marine organisms on substrates is important for the development of environmentally benign new methods for control of marine biofouling. The adhesion to substrates by spores of Undaria pinnatifida, a kelp species that is invasive to several countries, was studied by scanning electron and transmission electron microscopies (SEM/TEM) as well as by in situ attenuated total reflection infrared (ATR-IR) spectroscopy. The IR spectra showed that adhesive secretion began approximately 15 min after initial settlement and that the adhesive bulk material contained protein and anionic polysaccharides. Energy dispersive X-ray microanalysis of the adhesive identified sulphur and phosphorus as well as calcium and magnesium ions, which facilitate the gelation of the anionic polysaccharides in the sea water. The adhesive may be secreted from Golgi bodies in the spore, which were imaged by TEM of spore thin sections. Additionally, an in situ settlement study on TiO2 particle film by ATR-IR spectroscopy revealed the presence of phosphorylated moieties directly binding the substrate. The presence of anionic groups dominating the adhesive suggests that inhibition of spore adhesion will be favoured by negatively charged surfaces. PMID:20685693

  6. Focusing and matching properties of the ATR transfer line

    SciTech Connect

    Tsoupas, N.; Fischer, W.; Kewisch, J.; MacKay, W.W.; Peggs, S.; Pilat, F.; Tepikian, S.; Wei, J.

    1997-07-01

    The AGS to RHIC (AtR) beam transfer line has been constructed and will be used to transfer beam bunches from the AGS machine into the RHIC machine which is presently under construction at BNL. The original design of the AtR line has been modified. This article will present the optics of the various sections of the existing AtR beam line, as well as the matching capabilities of the AtR line to the RHIC machine.

  7. Mapping of healthy oral mucosal tissue using diffuse reflectance spectroscopy: ratiometric-based total hemoglobin comparative study.

    PubMed

    Hafez, Razan; Hamadah, Omar; Bachir, Wesam

    2015-11-01

    The objective of this study is to clinically evaluate the diffuse reflectance spectroscopy (DRS) ratiometric method for differentiation of normal oral mucosal tissues with different histological natures and vascularizations in the oral cavity. Twenty-one healthy patients aged 20-44years were diagnosed as healthy and probed with a portable DRS system. Diffuse reflectance spectra were recorded in vivo in the range (450-650nm). In this study, the following three oral mucosal tissues were considered: masticatory mucosa, lining mucosa, and specialized mucosa. Spectral features based on spectral intensity ratios were determined at five specific wavelengths (512, 540, 558, 575, and 620nm). Total hemoglobin based on spectral ratios for the three anatomical regions have also been evaluated. The three studied groups representing different anatomical regions in the oral cavity were compared using analysis of variance and post hoc least significant difference tests. Statistical analysis showed a significant difference in the mean of diffuse spectral ratios between the groups (P?total hemoglobin content. Diffuse reflectance spectroscopy might be used for creating a DRS databank of normal oral mucosal tissue with specific spectral ratios featuring the total hemoglobin concentrations. That would further enhance the discrimination of oral tissue for examining the histological nature of oral mucosa and diagnosis of early precancerous changes in the oral cavity based on non-invasive monitoring of neovascularization. PMID:25987341

  8. Overview of the ATR Power Supplies

    NASA Astrophysics Data System (ADS)

    Bruno, D.; Soukas, A.; Toldo, F.; Lambiase, B.

    1997-05-01

    The AGS to RHIC transfer Line (ATR) transports a variety of beams from the Alternating Gradient Synchrotron (AGS) which gets its input from the Booster Synchrotron. In turn, the Booster receives input beams from either a Tandem Van de Graaff (heavy ions) or a Linac(protons). The AGS extracts beam bunches, up to a rate of 30 Hertz, to the ATR which will eventually feed the Relativistic Heavy Ion Collider (RHIC) starting with the sextant test in January of 1996. The ATR is made up of the upgraded U line and the new W, X and Y lines. A test in 1995 transported beam to the end of the W line. During normal operation, a pulsed switching magnet at the end of the W line will bend the beam into the X line or the Y line so that the two rings in RHIC are filled with counter rotating beams. The ATR line is comprised of 80 power supplies (PS's), 17 of which are upgraded AGS PS's. The remaining 63 PS's were newly purchased. These PS's range from bipolar 600 watt linear type trim magnet PS's to 1 Megawatt, thyristor, dipole PS's. Results of the commissioning runs will be presented, as well as descriptions of regulation, filtering, and analog and digital controls.

  9. Overview of the ATR power supplies

    SciTech Connect

    Bruno, D.; Soukas, A.; Toldo, F.; Lambiase, R.F.

    1997-07-01

    The AGS to RHIC transfer line (ATR) transports a variety of beams from the Alternating Gradient Synchrotron (AGS) which gets its input from the Booster Synchrotron. In turn, the Booster receives input beams from either a Tandem Van de Graaff (heavy ions) or a Linac (protons). The AGS extracts beam bunches, up to a rate of 30 Hertz, to the ATR which feeds the Relativistic Heavy Ion Collider (RHIC) starting with the sextant test in January of 1997. The ATR is made up of the upgraded U line and the new W, X, and Y lines. A test in 1995 transported beam to the end of the W line. During normal operation, a pulsed switching magnet at the end of the W line will bend the beam into the X line or the Y line so that the two storage rings in RHIC are filled with counter rotating beams. The ATR line is comprised of 80 power supplies (PS`s), 17 of which are upgraded AGS PS`s. The remaining 63 PS`s were newly purchased. These PS`s range from bipolar 600 watt linear type trim magnet PS`s to 1 Megawatt, thyristor, dipole PS`s. Results of the commissioning runs will be presented, as well as descriptions of regulation, filtering, and analog and digital controls.

  10. Use of total-reflection X-ray fluorescence in search of a biomonitor for environmental pollution in Vietnam

    NASA Astrophysics Data System (ADS)

    Brauer, Hans; Wagner, Annemarie; Boman, Johan; Viet Binh, Doan

    2001-11-01

    The concentration of trace elements in tissues of several animals collected in the Ha Nam province, approximately 40 km south of Hanoi, Vietnam, has been investigated using total-reflection X-ray fluorescence analysis. We find that the freshwater mussel is probably the optimal choice of biomonitor for the pollution situation in Vietnam, but the freshwater crab, the toad and the catfish are also good candidates. The krait is probably also well suited for this purpose. It is shown that since several elements show a more or less pronounced accumulation tendency in a particular tissue it can be of great use to determine the levels in different tissues. When selecting an organism to be used as a biomonitor, other factors besides the mere concentration of trace elements must be considered, for instance the abundance and feeding habits.

  11. Fast high-resolution 3D total internal reflection fluorescence microscopy by incidence angle scanning and azimuthal averaging

    PubMed Central

    Boulanger, Jrme; Gueudry, Charles; Mnch, Daniel; Cinquin, Bertrand; Paul-Gilloteaux, Perrine; Bardin, Sabine; Gurin, Christophe; Senger, Fabrice; Blanchoin, Laurent; Salamero, Jean

    2014-01-01

    Total internal reflection fluorescence microscopy (TIRFM) is the method of choice to visualize a variety of cellular processes in particular events localized near the plasma membrane of live adherent cells. This imaging technique not relying on particular fluorescent probes provides a high sectioning capability. It is, however, restricted to a single plane. We present here a method based on a versatile design enabling fast multiwavelength azimuthal averaging and incidence angles scanning to computationally reconstruct 3D images sequences. We achieve unprecedented 50-nm axial resolution over a range of 800 nm above the coverslip. We apply this imaging modality to obtain structural and dynamical information about 3D actin architectures. We also temporally decipher distinct Rab11a-dependent exocytosis events in 3D at a rate of seven stacks per second. PMID:25404337

  12. Total internal reflection fluorescence correlation spectroscopy (TIR-FCS) with low background and high count-rate per molecule

    NASA Astrophysics Data System (ADS)

    Hassler, Kai; Leutenegger, Marcel; Rigler, Per; Rao, Ramachandra; Rigler, Rudolf; Gsch, Michael; Lasser, Theo

    2005-09-01

    We designed a fluorescence correlation spectroscopy (FCS) system for measurements on surfaces. The system consists of an objective-type total internal reflection fluorescence (TIRF) microscopy setup, adapted to measure FCS. Here, the fluorescence exciting evanescent wave is generated by epi-illumination through the periphery of a high NA oil-immersion objective. The main advantages with respect to conventional FCS systems are an improvement in terms of counts per molecule (cpm) and a high signal to background ratio. This is demonstrated by investigating diffusion as well as binding and release of single molecules on a glass surface. Furthermore, the size and shape of the molecule detection efficiency (MDE) function was calculated, using a wave-vectorial approach and taking into account the influence of the dielectric interface on the emission properties of fluorophores.

  13. Fast high-resolution 3D total internal reflection fluorescence microscopy by incidence angle scanning and azimuthal averaging.

    PubMed

    Boulanger, Jrme; Gueudry, Charles; Mnch, Daniel; Cinquin, Bertrand; Paul-Gilloteaux, Perrine; Bardin, Sabine; Gurin, Christophe; Senger, Fabrice; Blanchoin, Laurent; Salamero, Jean

    2014-12-01

    Total internal reflection fluorescence microscopy (TIRFM) is the method of choice to visualize a variety of cellular processes in particular events localized near the plasma membrane of live adherent cells. This imaging technique not relying on particular fluorescent probes provides a high sectioning capability. It is, however, restricted to a single plane. We present here a method based on a versatile design enabling fast multiwavelength azimuthal averaging and incidence angles scanning to computationally reconstruct 3D images sequences. We achieve unprecedented 50-nm axial resolution over a range of 800 nm above the coverslip. We apply this imaging modality to obtain structural and dynamical information about 3D actin architectures. We also temporally decipher distinct Rab11a-dependent exocytosis events in 3D at a rate of seven stacks per second. PMID:25404337

  14. Determination of copper, iron and zinc in spirituous beverages by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Capote, T.; Marcó, L. M.; Alvarado, J.; Greaves, E. D.

    1999-10-01

    The concentration of copper in traditional homemade alcoholic distillates produced in Venezuela (Cocuy de Penca) were determined by total reflection X-ray fluorescence (TXRF) using vanadium as internal standard. The results were compared to those obtained by flame atomic absorption spectrometry (FAAS). Three preparative methods of addition of vanadium were compared: classical internal standard addition, 'layer on layer' internal standard addition and in situ addition of internal standard. The TXRF procedures were accurate and the precision was comparable to that obtained by the FAAS technique. Copper levels were above the maximum allowed limits for similar beverages. Zinc and iron in commercial and homemade distilled beverages were also analyzed by TXRF with in situ addition of internal standard demonstrating the usefulness of this technique for trace metal determination in distillates.

  15. In-situ analysis of fruit anthocyanins by means of total internal reflectance, continuous wave and time-resolved spectroscopy

    NASA Astrophysics Data System (ADS)

    Zude, Manuela; Spinelli, Lorenzo; Dosche, Carsten; Torricelli, Alessandro

    2009-08-01

    In sweet cherry (Prunus avium), the red pigmentation is correlated with the fruit maturity stage and can be measured by non-invasive spectroscopy. In the present study, the influence of varying fruit scattering coefficients on the fruit remittance spectrum (cw) were corrected with the effective pathlength and refractive index in the fruit tissue obtained with distribution of time-of-flight (DTOF) readings and total internal reflection fluorescence (TIRF) analysis, respectively. The approach was validated on fruits providing variation in the scattering coefficient outside the calibration sample set. In the validation, the measuring uncertainty when non-invasively analyzing fruits with cw method in comparison with combined application of cw, DTOF, and TIRF measurements showed an increase in r2 up to 22.7 % with, however, high errors in all approaches.

  16. Determination of heavy metals in macrozoobenthos from the rivers Tisza and Szamos by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Woelfl, S.; Mages, M.; Óvári, M.; Geller, W.

    2006-11-01

    In 2000, accidents in the Romanian mining industry in key catchment areas led to heavy metal contamination of the Hungarian rivers Tisza and Szamos resulting in substantial heavy metal loads in several sediments of the upper river basins. This enhanced metal content might have been bioaccumulated in benthic organisms during the following years. Therefore, the aim of this study was to test, whether the zoobenthic fauna showed an enhanced metal content 3 years after the industrial accident. Macrozoobenthic insect larvae (chironomids) were sampled 100 m below and above the confluent site of the rivers Tisza and Szamos during summer 2003 and for comparison purpose also in the river Maros, a tributary of the Tisza river, during 2005. In order to determine their heavy metal content, single specimens were prepared and analysed by Total Reflection X-ray Fluorescence Spectrometry (TRXF) according to the modified dry method. Fe was much lower and Mn and Zn much higher concentrated in benthos from the more contaminated Szamos river compared to the Tisza and Maros rivers. In this sense, the benthic organisms reflected very well the enhanced metal concentrations in the contaminated rivers being suitable as bioindicators of metal contamination. However, the sediment bioaccumulation factor was low at all sampling sites indicating a low bioavailability of trace metals for benthic organisms.

  17. Monitoring the distribution of surfactants in the stratum corneum by combined ATR-FTIR and tape-stripping experiments.

    PubMed

    Hoppel, Magdalena; Holper, Evelyn; Baurecht, Dieter; Valenta, Claudia

    2015-01-01

    Combined ATR-FTIR (attenuated total reflection-Fourier transform infrared) spectroscopy and tape-stripping experiments in vitro on porcine ear skin were used to investigate the spatial distribution of different surfactants in the stratum corneum (SC). To reveal a possible connection between the size of the formed micelles and skin penetration, dynamic light-scattering measurements of the aqueous surfactant solutions were also taken. Compared to an alkyl polyglycoside and sucrose laurate, a deeper skin penetration of the anionic surfactants sodium dodecyl sulfate (SDS) und sodium lauryl ether sulfate (SLES) could be related to a smaller size of the formed micelles. Beside the differences in spatial distribution, a link between the physical presence of anionic surfactants in the SC and a decrease of skin hydration was found. Furthermore, the incorporation of SDS and SLES into the SC, even after a brief, consumer-orientated washing procedure with commercially available hair shampoos, was confirmed. PMID:25612540

  18. ATR-FTIR Spectroscopy for the Assessment of Biochemical Changes in Skin Due to Cutaneous Squamous Cell Carcinoma

    PubMed Central

    Lima, Cssio A.; Goulart, Viviane P.; Crrea, Luciana; Pereira, Thiago M.; Zezell, Denise M.

    2015-01-01

    Nonmelanoma skin cancers represent 95% of cutaneous neoplasms. Among them, squamous cell carcinoma (SCC) is the more aggressive form and shows a pattern of possible metastatic profile. In this work, we used Fourier transform infrared spectroscopy (FTIR) spectroscopy to assess the biochemical changes in normal skin caused by squamous cell carcinoma induced by multi-stage chemical carcinogenesis in mice. Changes in the absorption intensities and shifts were observed in the vibrational modes associated to proteins, indicating changes in secondary conformation in the neoplastic tissue. Hierarchical cluster analysis was performed to evaluate the potential of the technique to differentiate the spectra of neoplastic and normal skin tissue, so that the accuracy obtained for this classification was 86.4%. In this sense, attenuated total reflection (ATR)-FTIR spectroscopy provides a useful tool to complement histopathological analysis in the clinical routine for the diagnosis of cutaneous squamous cell carcinoma. PMID:25811925

  19. Formulation and drug-content assay of microencapsulated antisense oligonucleotide to NF-?B using ATR-FTIR

    NASA Astrophysics Data System (ADS)

    Siwale, Rodney; Meadows, Fred; Mody, Vicky V.; Shah, Samit

    2013-09-01

    Antisense oligonucleotide to NF-?B sequence: 5?-GGA AAC ACA TCC TCC ATG-3?, was microencapsulated in an albumin matrix by the method of spray dryingTM. Spectral analysis was performed on varying drug loading formulations of both drugs by mid-IR attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). An out of plane O-H bending vibration at 948 cm-1, unique to both the native and microencapsulated drugs was identified. The calculated peak areas corresponded to the drug loadings in the microsphere formulations. A standard curve could then be used to determine the drug content of an unknown microsphere formulation. Accuracy and precision were determined to be comparable to other analytical techniques such as HPLC.

  20. Surface-enhanced ATR-IR spectroscopy with interface-grown plasmonic gold-island films near the percolation threshold.

    PubMed

    Enders, Dominik; Nagao, Tadaaki; Pucci, Annemarie; Nakayama, Tomonobu; Aono, Masakazu

    2011-03-21

    Flat nano-island films prepared by wet-chemical deposition were investigated with attenuated total reflection infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) in order to analyze the correlation between film morphology and optical properties. Here we choose Au as representative coinage metal (Au, Ag, Cu) that shows strong structure-dependent surface-enhanced infrared absorption (SEIRA). Infrared spectra of octadecanethiol monolayers on films of different stages of morphologic development show effects that are characteristic for SEIRA, such as enhanced vibrational signals, Fano-type line shape, and adsorbate induced baseline shifts. Their extent was found to be strongly dependent on the structural details and the strongest enhancement occurs at the percolation threshold of the two-dimensional island system. Also films beyond percolation show significant enhancement due to residual nanoholes that are acting as hotspots. PMID:21293799

  1. Determination of V, Fe, Ni and S in petroleum crude oil by total-reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Ojeda, Nelson; Greaves, Eduardo D.; Alvarado, Jose; Sajo-Bohus, Laszlo

    1993-02-01

    The use of total-reflection X-ray fluorescence (TXRF) for the determination of S, V, Fe and Ni in crude petroleum oil samples is described. The advantages and limitations of the technique for this particular type of analysis are discussed. The method consists of the deposition of milligram or microliter quantities of the sample on a sample holder of a high-quality, optically flat surface made of pure fused SiO 2. The sample is irradiated with a collimated, filtered beam of X-rays at a small incident angle so that total reflection takes place at the specimen holder surface. The analysis is carried out on the crude petroleum oils with very little sample treatment. Homogenization is required to improve reproducibility of the measurements. Excitation was achieved with the L? lines of a tungsten X-ray tube operated at 45 kV and at 20 mA. Quantification was carried out using the scattered X-radiation of the exciting L-line of the tungsten tube as internal standard. Detection limits obtained were 20 ppm (= ?g g -1) for S, 0.6 ppm for V, 0.1 ppm for Fe and 0.4 ppm for Ni. Reproducibility, expressed as relative standard deviation (RSD), was in the range of 2-6%. Accuracy within the range of 4% was confirmed by the analysis of the standard reference material NIST 1634a and of samples that had been previously analyzed by atomic absorption or neutron activation techniques. Further confirmation of the accuracy of the method was obtained after comparison of results obtained by TXRF with those obtained by wavelength dispersive XRF analysis of a range of light and heavy Venezuelan crude oil samples.

  2. Serum Cystatin C Reflects Angiographic Coronary Collateralization in Stable Coronary Artery Disease Patients with Chronic Total Occlusion

    PubMed Central

    Zhang, Rui Yan; Zhang, Qi; Lu, Lin; Shen, Wei Feng

    2015-01-01

    Objective We investigated whether and to what extent cystatin C was associated with angiographic coronary collateralization in patients with stable coronary artery disease and chronic total occlusion. Methods Serum levels of cystatin C and high-sensitive C-reactive protein (hsCRP) and glomerular filtration rate (GFR) were determined in 866 patients with stable angina and angiographic total occlusion of at least one major coronary artery. The degree of collaterals supplying the distal aspect of a total occlusion from the contra-lateral vessel was graded as poor (Rentrop score of 0 or 1) or good coronary collateralization (Rentrop score of 2 or 3). Results In total, serum cystatin C was higher in patients with poor collateralization than in those with good collateralization (1.08 ± 0.32 mg/L vs. 0.90 ± 0.34 mg/L, P < 0.001), and correlated inversely with Rentrop score (adjusted Spearmen’s r = -0.145, P < 0.001). The prevalence of poor coronary collateralization increased stepwise with increasing cystatin C quartiles (P for trend < 0.001). After adjusting for age, gender, risk factors for coronary artery disease, GFR and hsCRP, serum cystatin C ≥ 0.97 mg/L remained independently associated with poor collateralization (OR 2.374, 95% CI 1.660 ~ 3.396, P < 0.001). The diagnostic value of cystatin C levels for detecting poor coronary collateralization persisted regardless of age, gender, presence or absence of diabetes, hypertension or renal dysfunction. Conclusions Serum cystatin C reflects angiographic coronary collateralization in patients with stable coronary artery disease, and cystatin C ≥ 0.97 mg/L indicates a great risk of poor coronary collaterals. PMID:26402227

  3. The distribution of atrazine (ATR) and ATR metabolites in the Wistar rat following gestational/lactational exposures

    EPA Science Inventory

    Gestational/lactational exposure to ATR is reported to alter reproductive/developmental function, yet our understanding of the transfer of ATR and/or its metabolites from the dam to the fetus/offspring is limited. Previously we examined the lactational transfer of CI4-ATR, but sp...

  4. Design, simulation and fabrication of a total internal reflection (TIR)-based chip for highly sensitive fluorescent imaging

    NASA Astrophysics Data System (ADS)

    Le, Nam Cao Hoai; Dao, Dzung Viet; Yokokawa, Ryuji; Wells, John; Sugiyama, Susumu

    2007-06-01

    This paper presents a total internal reflection based chip which generates evanescent waves for highly sensitive fluorescent imaging. The chip is monolithically, massively cast in polydimethylsiloxane (PDMS) at a very low cost using a Si mold fabricated by Si anisotropic wet etching and deep reactive ion etching (DRIE). Our method integrates all miniaturized optical components, namely cylindrical microlens, prism and waveguide, into one monolithic PDMS chip; thus assembly is unnecessary, and misalignment is eliminated. The slide-format and monolithic chip can be used with both upright and inverted fluorescent microscopes with flexible sample delivery platforms. The flexibility of sample delivery platforms facilitates various surface treatment/immobilization techniques required in fluorescent imaging. Moreover, the fiberoptics coupling into the chip allows a broad choice of wavelengths and types of laser sources ranging from UV to IR. We have successfully demonstrated the capability of the chip in highly sensitive imaging of tetramethylrhodamine (TMR) fluorescent dye and immobilized fluorescent nanobeads. Our monolithic, miniaturized TIR-based chip could potentially serve as an evanescent excitation-based platform integrated into a micro-total analysis system (?-TAS).

  5. Surfactant adsorption kinetics by total internal reflection Raman spectroscopy. 2. CTAB and Triton X-100 mixtures on silica.

    PubMed

    Woods, David A; Petkov, Jordan; Bain, Colin D

    2011-06-01

    Total internal reflection (TIR) Raman spectroscopy has been used to study the kinetics of adsorption, desorption, and displacement of mixed surfactant systems at the silica-water interface. The limited penetration depth of the evanescent wave provides surface sensitivity while the chemical sensitivity of Raman scattering permits the determination of the time-dependent composition of the adsorbed film. Principal component analysis is used to deconvolute the Raman spectra with a time resolution of 2 s and a precision of 5% of a monolayer. Both equilibrium and kinetic measurements are presented for the cetyltrimethylammonium bromide (CTAB)/Triton X-100 system over a range of concentrations and compositions. For a total concentration of 2 mM, the adsorption isotherm shows strong synergistic behavior with the addition of small amounts of CTAB (?2% of the total surfactant) doubling the adsorbed amount of Triton X-100. This synergism has a marked influence on the kinetics: for example, when Triton X-100 replaces CTAB, the Triton X-100 surface excess overshoots its equilibrium value and returns only very slowly to equilibrium. For systems above the cmc, the repartitioning of surfactant between micelles and monomers results in unexpected behavior during exchange or rinsing of mixed surfactant solutions. For example, during rinsing, the more rapid diffusion of CTAB away from the surface leads to a local increase in the monomer concentration of Triton X-100, resulting in a temporary spike in the Triton X-100 surface excess. Displacement kinetics of CTAB by TX-100 and vice versa are generally slower than the adsorption or desorption of the pure surfactants but cover a wide range of kinetic time scales, depending on the details of the compositions and concentrations of the initial and final solutions. PMID:21591653

  6. An ATR-FTIR spectroscopic approach for measuring rapid kinetics at the mineral/water interface.

    PubMed

    Parikh, S J; Lafferty, B J; Sparks, D L

    2008-04-01

    This study presents a methodology for studying rapid kinetic reactions for IR active compounds. In soils, sediments, and groundwater systems a rapid initial chemical reaction can comprise a substantial portion of the total reaction process at the mineral/water interface. Rapid-scan attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy is presented here as a new method for collecting rapid in situ kinetic data. As an example of its application, the initial oxidation of arsenite (As III) via Mn-oxides is examined. Using a rapid-scan technique, IR spectra were collected with a time resolution of up to 2.55 s (24 scans, 8 cm(-1) resolution). Through observation and analysis of IR bands corresponding to arsenate (AsV), rapid chemically-controlled As III oxidation is observed (initial pH 6-9) with 50% of the reaction occurring within the first one min. The oxidation of As III is followed by rapid binding of AsV to HMO, at least in part, through surface bound Mn II. The experimental data indicate that rapid-scan FTIR is an effective technique for acquisition of kinetic data, providing molecular scale information for rapid reactions at the solid/liquid interface. PMID:18222461

  7. Use of attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy in direct, non-destructive, and rapid assessment of developmental cotton fibers grown in planta and in culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 at controlled laboratory environments, so that cotton researchers can investigate many aspects of experimental protocols in cotton bre...

  8. 10 CFR 830 Major Modification Determination for Replacement of ATR Primary Coolant Pumps and Motors

    SciTech Connect

    Noel Duckwitz

    2011-05-01

    The continued safe and reliable operation of the ATR is critical to the Department of Energy (DOE) Office of Nuclear Energy (NE) mission. While ATR is safely fulfilling current mission requirements, a variety of aging and obsolescence issues challenge ATR engineering and maintenance personnel’s capability to sustain ATR over the long term. First documented in a series of independent assessments, beginning with an OA Environmental Safety and Health Assessment conducted in 2003, the issues were validated in a detailed Material Condition Assessment (MCA) conducted as a part of the ATR Life Extension Program in 2007.Accordingly, near term replacement of aging and obsolescent original ATR equipment has become important to ensure ATR capability in support of NE’s long term national missions. To that end, a mission needs statement has been prepared for a non-major system acquisition which is comprised of three interdependent subprojects. The first project will replace the existent diesel-electrical bus (E-3), switchgear, and the 50-year-old obsolescent marine diesels with commercial power that is backed with safety related emergency diesel generators, switchgear, and uninterruptible power supply (UPS). The second project, the subject of this major modification determination, will replace the four, obsolete, original primary coolant pumps (PCPs) and motors. Completion of this and the two other age-related projects (replacement of the ATR diesel bus [E-3] and switchgear and replacement of the existent emergency firewater injection system) will resolve major age-related operational issues plus make a significant contribution in sustaining the ATR safety and reliability profile. The major modification criteria evaluation of the project pre-conceptual design identified several issues that lead to the conclusion that the project is a major modification: 1. Evaluation Criteria #3 (Change of existing process). The proposed strategy for equipping the replacement PCPs with VFDs and having the PCPs also function as ECPs will require significant safety basis changes requiring DOE approval. 2. Evaluation Criteria #4 (Use of new technology). The use of VFD and VFD “pump catcher” technology for the PCPs is not currently in use and has not been previously formally reviewed/approved by DOE for ATR. It is noted that VFD technology has several decades of commercial use and experience. However, the ATR probabilistic risk assessment will have to be updated, reflecting the changes for supplying ECP flows including VFD reliability, to confirm that the proposed activity maintains or reduces the CDF for the ATR. 3. Evaluation Criteria #5 (Create the need for new or revised safety SSCs). It is expected that the proposed activity will result in a revised list of safety-related SSCs. Specifically, as currently proposed, the existing ECPs will be deleted from the list. The PCPs and their associated components, picking up the ECP function, will be classified as safety-related active Seismic Category I.

  9. A Simplified Shuttle Irradiation Facility for ATR

    SciTech Connect

    A. J. Palmer; S. T. Laflin

    1999-08-01

    During the past fifteen years there has been a steady increase in the demand for radioisotopes in nuclear medicine and a corresponding decline in the number of reactors within the U.S. capable of producing them. The Advanced Test Reactor (ATR) is the largest operating test reactor in the U.S., but its isotope production capabilities have been limited by the lack of an installed isotope shuttle irradiation system. A concept for a simple "low cost" shuttle irradiation facility for ATR has been developed. Cost were reduced (in comparison to previous ATR designs) by using a shielded trough of water installed in an occupiable cubicle as a shielding and contamination control barrier for the send and receive station. This shielding concept also allows all control valves to be operated by hand and thus the need for an automatic control system was eliminated. It was determined that 4-5 ft of water would be adequate to shield the isotopes of interest while shuttles are transferred to a small carrier. An additional feature of the current design is a non-isolatable by-pass line, which provides a minimum coolant flow to the test region regardless of which control valves are opened or closed. This by-pass line allows the shuttle facility to be operated without bringing reactor coolant water into the cubicle except for send and receive operations.

  10. Automated rapid training of ATR algorithms

    NASA Astrophysics Data System (ADS)

    McBride, Jonah; Lowell, Jessica; Snorrason, Magnús; Eaton, Ross; Irvine, John

    2009-05-01

    Computer vision methods, such as automatic target recognition (ATR) techniques, have the potential to improve the accuracy of military systems for weapon deployment and targeting, resulting in greater utility and reduced collateral damage. A major challenge, however, is training the ATR algorithm to the specific environment and mission. Because of the wide range of operating conditions encountered in practice, advanced training based on a pre-selected training set may not provide the robust performance needed. Training on a mission-specific image set is a promising approach, but requires rapid selection of a small, but highly representative training set to support time-critical operations. To remedy these problems and make short-notice seeker missions a reality, we developed Learning and Mining using Bagged Augmented Decision Trees (LAMBAST). LAMBAST examines large databases and extracts sparse, representative subsets of target and clutter samples of interest. For data mining, LAMBAST uses a variant of decision trees, called random decision trees (RDTs). This approach guards against overfitting and can incorporate novel, mission-specific data after initial training via perpetual learning. We augment these trees with a distribution modeling component that eliminates redundant information, ignores misrepresentative class distributions in the database, and stops training when decision boundaries are sufficiently sampled. These augmented random decision trees enable fast investigation of multiple images to train a reliable, mission-specific ATR. This paper presents the augmented random decision tree framework, develops the sampling procedure for efficient construction of the sample, and illustrates the procedure using relevant examples.

  11. Function of the ATR N-terminal domain revealed by an ATM/ATR chimera

    SciTech Connect

    Chen Xinping; Zhao Runxiang; Glick, Gloria G.; Cortez, David . E-mail: david.cortez@vanderbilt.edu

    2007-05-01

    The ATM and ATR kinases function at the apex of checkpoint signaling pathways. These kinases share significant sequence similarity, phosphorylate many of the same substrates, and have overlapping roles in initiating cell cycle checkpoints. However, they sense DNA damage through distinct mechanisms. ATR primarily senses single stranded DNA (ssDNA) through its interaction with ATRIP, and ATM senses double strand breaks through its interaction with Nbs1. We determined that the N-terminus of ATR contains a domain that binds ATRIP. Attaching this domain to ATM allowed the fusion protein (ATM*) to bind ATRIP and associate with RPA-coated ssDNA. ATM* also gained the ability to localize efficiently to stalled replication forks as well as double strand breaks. Despite having normal kinase activity when tested in vitro and being phosphorylated on S1981 in vivo, ATM* is defective in checkpoint signaling and does not complement cellular deficiencies in either ATM or ATR. These data indicate that the N-terminus of ATR is sufficient to bind ATRIP and to promote localization to sites of replication stress.

  12. A novel total reflection X-ray fluorescence procedure for the direct determination of trace elements in petrochemical products.

    PubMed

    Cinosi, Amedeo; Andriollo, Nunzio; Pepponi, Giancarlo; Monticelli, Damiano

    2011-01-01

    A total reflection X-ray fluorescence (TXRF) procedure was developed for the determination of metal traces in petrochemical end products or intermediates for surfactant synthesis. The method combines a fast and straightforward sample preparation, i.e. deposition on the sample holder and evaporation of the sample matrix, with an efficient quantification method based on internal standardization (organic gallium standard). The method developed showed detection limits below 0.05?gg(-1) and in most cases below 0.005?gg(-1). Fifteen elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rh, Sn, Sr, V and Zn) were determined in matrices such as paraffins, n-olefins, linear alkylbenzenes, long-chain alkyl alcohols and esters: typical metal contents were below 1?gg(-1). The results were compared with the reference method ASTM D5708 (test method B) based on inductively coupled plasma optical emission spectroscopy: advantages and drawbacks of the two procedures were critically evaluated. The TXRF method developed showed comparable precision and absence of bias with respect to the reference method. A comparison of the performances of the two methods is presented. PMID:21046076

  13. Bayesian total internal reflection fluorescence correlation spectroscopy reveals hIAPP-induced plasma membrane domain organization in live cells.

    PubMed

    Guo, Syuan-Ming; Bag, Nirmalya; Mishra, Aseem; Wohland, Thorsten; Bathe, Mark

    2014-01-01

    Amyloid fibril deposition of human islet amyloid polypeptide (hIAPP) in pancreatic islet cells is implicated in the pathogenesis of type II diabetes. A growing number of studies suggest that small peptide aggregates are cytotoxic via their interaction with the plasma membrane, which leads to membrane permeabilization or disruption. A recent study using imaging total internal reflection-fluorescence correlation spectroscopy (ITIR-FCS) showed that monomeric hIAPP induced the formation of cellular plasma membrane microdomains containing dense lipids, in addition to the modulation of membrane fluidity. However, the spatial organization of microdomains and their temporal evolution were only partially characterized due to limitations in the conventional analysis and interpretation of imaging FCS datasets. Here, we apply a previously developed Bayesian analysis procedure to ITIR-FCS data to resolve hIAPP-induced microdomain spatial organization and temporal dynamics. Our analysis enables the visualization of the temporal evolution of multiple diffusing species in the spatially heterogeneous cell membrane, lending support to the carpet model for the association mode of hIAPP aggregates with the plasma membrane. The presented Bayesian analysis procedure provides an automated and general approach to unbiased model-based interpretation of imaging FCS data, with broad applicability to resolving the heterogeneous spatial-temporal organization of biological membrane systems. PMID:24411251

  14. Inorganic pigment study of the San Pedro Gonzalez Telmo Sibyls using total reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Vázquez, Cristina; Custo, Graciela; Barrio, Néstor; Burucúa, José; Boeykens, Susana; Marte, Fernando

    2010-09-01

    This article describes the study carried out on a series of oil paintings on canvas from the eighteenth century that were restored at Centro de Producción e Investigación en Restauración y Conservación Artística y Bibliográfica - Tarea (CEIRCAB-Tarea), Buenos Aires, Argentina: the San Pedro González Telmo Sibyls. Experimental study was undertaken to identify inorganic pigments and the technique used in their confection; and, in this way, try to add information about their local origin. Therefore special emphasis was put to infer technologies used in the manufacturing of these paintings. Elemental analysis was performed by total reflection X-ray fluorescence spectrometry (TXRF) and complemented by optical and polarized light microscopy. Microsampling was carefully done over areas of the paintings which were damaged and where a small additional loss will not be noticed. This investigation has shown that a variety of pigments were used, namely earth pigments (red and yellow ochres), white lead, vermilion, etc., and they were used either pure or in mixtures. This characterization helped conservators in their decisions regarding a better understanding of the deterioration processes. In addition, this research about the material composition allowed the art historians and restorers the possibility to obtain information about where, when or by whom The San Pedro González Telmo Sibyls may have been painted.

  15. Planar solar concentrator featuring alignment-free total-internal-reflection collectors and an innovative compound tracker.

    PubMed

    Teng, Tun-Chien; Lai, Wei-Che

    2014-12-15

    This study proposed a planar solar concentrator featuring alignment-free total-internal-reflection (TIR) collectors and an innovative compound tracker. The compound tracker, combining a mechanical single-axis tracker and scrollable prism sheets, can achieve a performance on a par with dual-axis tracking while reducing the cost of the tracking system and increasing its robustness. The alignment-free TIR collectors are assembled on the waveguide without requiring alignment, so the planar concentrator is relatively easily manufactured and markedly increases the feasibility for use in large concentrators. Further, the identical TIR collector is applicable to various-sized waveguide slab without requiring modification, which facilitates flexibility regarding the size of the waveguide slab. In the simulation model, the thickness of the slab was 2 mm, and its maximal length reached 6 m. With an average angular tolerance of 0.6, and after considering both the Fresnel loss and the angular spread of the sun, the simulation indicates that the waveguide concentrator of a 1000-mm length provides the optical efficiencies of 62-77% at the irradiance concentrations of 387-688, and the one of a 2000-mm length provides the optical efficiencies of 52-64.5% at the irradiance concentrations of 645-1148. Alternatively, if a 100-mm horizontally staggered waveguide slab is collocated with the alignment-free TIR collectors, the optical efficiency would be greatly improved up to 91.5% at an irradiance concentration of 1098 (C(geo) = 1200X). PMID:25607496

  16. Assessment of serum selenium levels in 2-month-old sucking calves using total reflection X-ray fluorescence technique

    NASA Astrophysics Data System (ADS)

    Buoso, M. C.; Ceccato, D.; Moschini, G.; Bernardini, D.; Testoni, S.; Torboli, A.; Valdes, M.

    2001-11-01

    The assessment of selenium status of livestock plays an important role in the production of medicine since low serum Se levels influence disease resistance in ruminants. It has been proved that Se deficiency may cause muscular dystrophy, cardiomyopathy and even death. Serum level has been widely used to evaluate the Se short-term status in animals since there is a good association between serum Se level and the dietary intake of the element over a wide range. The purpose of this work was to determine the Se serum concentration in a population of 78 sucking 2-month-old calves, in order to corroborate a clinical diagnosis of severe deficiency status. The samples were analyzed by total reflection X-ray fluorescence (TXRF) at the ITAL STRUCTURES Research Laboratory. The results obtained from the serum samples presented Se concentrations varying from 10 to 66 ng/ml. The comparison between the obtained values and the expected serum selenium values (60-80 ng/ml), confirmed a mild to severe deficiency status in the investigated population.

  17. Determination of trace perchlorate concentrations by anion-selective membranes and total reflection X-ray fluorescence analysis.

    PubMed

    Hatzistavros, Vasilios S; Kallithrakas-Kontos, Nikolaos G

    2011-05-01

    In the present work a method for the determination of perchlorate trace levels by total reflection X-ray fluorescence (TXRF) is introduced. Perchlorate anions were concentrated on anion-selective membranes that had been prepared on the surface of TXRF quartz reflectors. Various complexation substances were used in the membranes. The reflectors were immersed in water solutions containing nanogram per milliliter (ppb) concentrations of perchlorate. After this step, the reflectors were taken out of the solution and they were analyzed by TXRF, using a copper X-ray tube and helium flow on the target (to lower the argon peak which is present in the air). The effects of various experimental parameters were examined, and the possibility of discrimination between chloride and perchlorate anions was shown. Minimum detection limits lower than 1 ng/mL and good linearity at the concentration range of 1-50 ng/mL were achieved. The method is applicable for the analysis of perchlorate in drinking water samples. PMID:21462926

  18. Determination of platinum group metal catalyst residues in active pharmaceutical ingredients by means of total reflection X-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Margu, Eva; Queralt, Ignasi; Hidalgo, Manuela

    2013-08-01

    The control of metal catalyst residues (i.e., platinum group metals (PGMs)) in different stages of the manufacturing processes of the active pharmaceutical ingredients (APIs) and, especially, in the final product is crucial. For API specimens, there are strict guidelines to limit the levels of metal residues based on their individual levels of safety concern. For PGMs the concentration limit has been established at 10 mg/kg in the API. Therefore great effort is currently being devoted to the development of new and simple procedures to control metals in pharmaceuticals. In the present work, an analytical methodology based on benchtop total reflection X-ray fluorescence spectrometry (TXRF) has been developed for the rapid and simple determination of some PGM catalyst impurities (Rh, Pd, Ir and Pt) in different types of API samples. An evaluation of different sample treatments (dissolution and digestion of the solid pharmaceutical samples) has been carried out and the developed methodologies have been validated according to the analytical parameters to be considered and acceptance criteria for PGM determination according to the United States Pharmacopeia (USP). Limits of quantification obtained for PGM metals were in the range of 2-4 mg/kg which are satisfactory according to current legislation. From the obtained results it is shown that the developed TXRF method can be implemented in the pharmaceutical industries to increase productivity of the laboratory; offering an interesting and complementary analytical tool to other atomic spectroscopic methods.

  19. 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.

  20. Element determination in natural biofilms of mine drainage water by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Mages, Margarete; von Tmpling, Wolf; van der Veen, Andrea; Baborowski, Martina

    2006-11-01

    Human impacts like mining activities lead to higher element concentration in surface waters. For different pollution levels, the consequences for aquatic organisms are not yet investigated in detail. Therefore, the aim of this investigation is to determine the influence of mining affected surface waters on biofilms. Elements like heavy metals can be absorbed on cell walls and on polymeric substances or enter the cytoplasm of the cells. Thus, they are important for the optimization of industrial biotechnological processes and the environmental biotechnology. Beyond this, biofilms can also play an important role in wastewater treatment processes and serve as bioindicators in the aquatic environment. The presented total reflection X-ray fluorescence spectroscopic investigation was performed to compare the element accumulation behavior of biofilms grown on natural or on artificial materials of drainage water affected by former copper mining activities. A high salt and heavy metal pollution is characteristic for the drainage water. For an assessment of these results, samples from stream Schlenze upstream the confluence with the drainage water, a small tributary of the Saale River in central Germany, were analyzed, too.

  1. Lateral Mobility of Membrane-Binding Proteins in Living Cells Measured by Total Internal Reflection Fluorescence Correlation Spectroscopy

    PubMed Central

    Ohsugi, Yu; Saito, Kenta; Tamura, Mamoru; Kinjo, Masataka

    2006-01-01

    Total internal reflection fluorescence correlation spectroscopy (TIR-FCS) allows us to measure diffusion constants and the number of fluorescent molecules in a small area of an evanescent field generated on the objective of a microscope. The application of TIR-FCS makes possible the characterization of reversible association and dissociation rates between fluorescent ligands and their receptors in supported phospholipid bilayers. Here, for the first time, we extend TIR-FCS to a cellular application for measuring the lateral diffusion of a membrane-binding fluorescent protein, farnesylated EGFP, on the plasma membranes of cultured HeLa and COS7 cells. We detected two kinds of diffusional motionfast three-dimensional diffusion (D1) and much slower two-dimensional diffusion (D2), simultaneously. Conventional FCS and single-molecule tracking confirmed that D1 was free diffusion of farnesylated EGFP close to the plasma membrane in cytosol and D2 was lateral diffusion in the plasma membrane. These results suggest that TIR-FCS is a powerful technique to monitor movement of membrane-localized molecules and membrane dynamics in living cells. PMID:16891361

  2. Determination of some heavy metals (Fe, Cu, Zn and Pb) in blood by total reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Bounakhla, M.; Doukkali, A.; Lalaoui, K.; Aguenaou, H.; Mokhtar, N.; Attrassi, B.

    2003-05-01

    The main purpose of this study is the interaction between nutrition (micronutrients heavy metals: Fe, Zn, Cu) and toxic heavy metals such as Pb in blood of children living in Gharb region of Morocco. This region receives all pollution carried by the Sebou river coming mainly from industrial activities. A rapid and simple analytical procedure was used for the determination of Fe, Cu and Zn trace amounts in blood by total-reflection X-ray fluorescence technique. This method is an energy dispersive XRF technique in a special geometry of primary beam, sample and detector. The sample is deposited on a plane polished surface of a suitable reflector material. It is presented as a few drops (25 ?l) from a solution of blood digested in a mixture of HNO3 and H2O2 using a microwaves accelerated reaction system. The accuracy of measurements has been investigated by using certified materials. The concentration of Cu was found to be normal in all samples (\\cong1 ppm) which ruled out any interaction between this element and the others. On the other hand, amounts of Fe and Zn are very variables, suggesting an interaction between Fe and Zn. However, amounts of Pb in blood are inferior to 50 ppb, suggesting that no interaction exist with this metal and micronutrients.

  3. Quantifying Exocytosis by Combination of Membrane Capacitance Measurements and Total Internal Reflection Fluorescence Microscopy in Chromaffin Cells

    PubMed Central

    Becherer, Ute; Pasche, Mathias; Nofal, Shahira; Hof, Detlef; Matti, Ulf; Rettig, Jens

    2007-01-01

    Total internal reflection fluorescence microscopy (TIRF-Microscopy) allows the observation of individual secretory vesicles in real-time during exocytosis. In contrast to electrophysiological methods, such as membrane capacitance recording or carbon fiber amperometry, TIRF-Microscopy also enables the observation of vesicles as they reside close to the plasma membrane prior to fusion. However, TIRF-Microscopy is limited to the visualization of vesicles that are located near the membrane attached to the glass coverslip on which the cell grows. This has raised concerns as to whether exocytosis measured with TIRF-Microscopy is comparable to global secretion of the cell measured with membrane capacitance recording. Here we address this concern by combining TIRF-Microscopy and membrane capacitance recording to quantify exocytosis from adrenal chromaffin cells. We found that secretion measured with TIRF-Microscopy is representative of the overall secretion of the cells, thereby validating for the first time the TIRF method as a measure of secretion. Furthermore, the combination of these two techniques provides a new tool for investigating the molecular mechanism of synaptic transmission with combined electrophysiological and imaging techniques. PMID:17551585

  4. A total internal reflection ellipsometry and atomic force microscopy study of interactions between Proteus mirabilis lipopolysaccharides and antibodies.

    PubMed

    Gleńska-Olender, J; Sęk, S; Dworecki, K; Kaca, W

    2015-07-01

    Specific antigen-antibody interactions play a central role in the human immune system. The objective of this paper is to detect immune complexes using label-free detection techniques, that is, total internal reflection ellipsometry (TIRE) and atomic force microscopy (AFM)-based topography and recognition imaging. Interactions of purified rabbit immunoglobulin G (IgG) antibodies with bacterial endotoxins (Proteus mirabilis S1959 O3 lipopolysaccharides) were studied. Lipopolysaccharide was adsorbed on gold surface for TIRE. In the AFM imaging experiments, LPS was attachment to the PEG linker (AFM tip modification). The mica surface was covered by IgG. In TIRE, the optical parameters Ψ and Δ change when a complex is formed. It was found that even highly structured molecules, such as IgG antibodies (anti-O3 LPS rabbit serum), preserve their specific affinity to their antigens (LPS O3). LPS P. mirabilis O3 response of rabbit serum anti-O3 was also tested by topography and recognition imaging. Both TIRE and AFM techniques were recruited to check for possible detection of antigen-antibody recognition event. The presented data allow for determination of interactions between a variety of biomolecules. In future research, this technique has considerable potential for studying a wide range of antigen-antibody interactions and its use may be extended to other biomacromolecular systems. PMID:25854960

  5. Intelligent Simultaneous Quantitative Online Analysis of Environmental Trace Heavy Metals with Total-Reflection X-Ray Fluorescence

    PubMed Central

    Ma, Junjie; Wang, Yeyao; Yang, Qi; Liu, Yubing; Shi, Ping

    2015-01-01

    Total-reflection X-ray fluorescence (TXRF) has achieved remarkable success with the advantages of simultaneous multi-element analysis capability, decreased background noise, no matrix effects, wide dynamic range, ease of operation, and potential of trace analysis. Simultaneous quantitative online analysis of trace heavy metals is urgently required by dynamic environmental monitoring and management, and TXRF has potential in this application domain. However, it calls for an online analysis scheme based on TXRF as well as a robust and rapid quantification method, which have not been well explored yet. Besides, spectral overlapping and background effects may lead to loss of accuracy or even faulty results during practical quantitative TXRF analysis. This paper proposes an intelligent, multi-element quantification method according to the established online TXRF analysis platform. In the intelligent quantification method, collected characteristic curves of all existing elements and a pre-estimated background curve in the whole spectrum scope are used to approximate the measured spectrum. A novel hybrid algorithm, PSO-RBFN-SA, is designed to solve the curve-fitting problem, with offline global optimization and fast online computing. Experimental results verify that simultaneous quantification of trace heavy metals, including Cr, Mn, Fe, Co, Ni, Cu and Zn, is realized on the online TXRF analysis platform, and both high measurement precision and computational efficiency are obtained. PMID:25954949

  6. Influenza hemagglutinin assumes a tilted conformation during membrane fusion as determined by attenuated total reflection FTIR spectroscopy.

    PubMed Central

    Tatulian, S A; Hinterdorfer, P; Baber, G; Tamm, L K

    1995-01-01

    Fusion of influenza virus with target membranes is mediated by an acid-induced conformational change of the viral fusion protein hemagglutinin (HA) involving an extensive reorganization of the alpha-helices. A 'spring-loaded' displacement over at least 100 A provides a mechanism for the insertion of the fusion peptide into the target membrane, but does not explain how the two membranes are brought into fusion contact. Here we examine, by attenuated total reflection Fourier transform infrared spectroscopy, the secondary structure and orientation of HA reconstituted in planar membranes. At neutral pH, the orientation of the HA trimers in planar membranes is approximately perpendicular to the membrane. However, at the pH of fusion, the HA trimers are tilted 55-70 degrees from the membrane normal in the presence or absence of bound target membranes. In the absence of target membranes, the overall secondary structure of HA at the fusion pH is similar to that at neutral pH, but approximately 50-60 additional residues become alpha-helical upon the conformational change in the presence of bound target membranes. These results are discussed in terms of a structural model for the fusion intermediate of influenza HA. Images PMID:8521808

  7. Determination of trace element distribution in cancerous and normal human tissues by total reflection X-ray fluorescence analysis

    NASA Astrophysics Data System (ADS)

    von Czarnowski, D.; Denkhaus, E.; Lemke, K.

    1997-07-01

    The intention of this study was to establish a method for cancer diagnosis. For this purpose, different trace element distributions in carcinomas of the digestive tract and in normal tissues of human stomach, colon and rectum in correlation to the type of cancer were determined by total reflection X-ray fluorescence analysis (TXRF). The tissue samples were frozen and cut by a microtome into 10 ?m sections, and a modified sample excision technique was introduced according to the aim of this research. After drying and spiking of the tissue sections, more than 20 elements, especially biologically relevant ones, were determined. The repeatabilities of measurements of element concentrations in malignant and normal tissues were calculated to be 10-30% (RSD) depending on the specific element. The concentration of Ca was found to be virtually constant (0.2500.025 ?g per 0.1 mm 3) in normal tissue and in carcinoma of the digestive organs. A significant diminution of Cr, Fe and Ni in carcinoma of the stomach, of Cr and Co in carcinoma of the colon and a significant accumulation of K in cancerous tissue of the colon and of Fe and K in neoplastic tissue of the rectum were discovered for a very limited population of patients.

  8. FT-IR-ATR study of depth profile of SiO 2 ultra-thin films

    NASA Astrophysics Data System (ADS)

    Nagai, N.; Hashimoto, H.

    2001-03-01

    It is very important to characterize the depth change in chemical bonding structures of ultra-thin SiO 2 films. The LO mode and the lower frequency shoulder peak of SiO 2 on Si was detected by the FT-IR-ATR method, and this band was simulated by a gradient layered and effective medium model. Interface roughness estimated from the shoulder bands of ATR spectra was in good agreement with the GIXR results, and the shoulder band also reflects the change of Si-O-Si bonding angle. In our calculation, the shoulder band around 1150-1050 cm -1 reflects the interface roughness and the shoulder band around 1250-1150 cm -1 includes information about the change of Si-O-Si bonding angle and/or Si-O force constant. The FT-IR-ATR method is a useful technique with which to characterize SiO 2 ultra-thin films.

  9. Noninvasive detection by ATR and NIR-DR methods for skin-care ionic materials transported into the skin by iontophoresis

    NASA Astrophysics Data System (ADS)

    Ueda, Toyotoshi; Watanabe, Yukio; Akao, Ken-ichi; Suzuki, Harue

    2003-12-01

    Two analytical methods without damage to the skin were proposed in order to detect and measure the quantity of the medication transported into the skin by the iontophoresis. The infrared attenuated total reflection (ATR) method was proven to be able to evaluate the content of such a substance as sodium all- trans-retinoate or magnesium ?-ascorbyl-2-phosphate in the top (horny) layer of epidermis (about 1 ?m under the skin surface), using characteristic bands to the above ion. Another method of near-infrared diffusive-reflection (NIR-DR) technique was shown probably to detect it in the dermis (1 mm under the surface), based on the shift of frequency and the change in intensity for the vibrational combination band of water molecules hydrating the ion. The quantity of the above material decreased monotonically in the horny layer for several hours after the treatment, while in the dermis it increased at first and then decreased via the maximum value.

  10. ATR promotes cilia signalling: links to developmental impacts

    PubMed Central

    Stiff, Tom; Casar Tena, Teresa; O'Driscoll, Mark; Jeggo, Penny A.; Philipp, Melanie

    2016-01-01

    Mutations in ATR (ataxia telangiectasia and RAD3-related) cause Seckel syndrome (ATR-SS), a microcephalic primordial dwarfism disorder. Hitherto, the clinical manifestation of ATR deficiency has been attributed to its canonical role in DNA damage response signalling following replication fork stalling/collapse. Here, we show that ATR regulates cilia-dependent signalling in a manner that can be uncoupled from its function during replication. ATR-depleted or patient-derived ATR-SS cells form cilia of slightly reduced length but are dramatically impaired in cilia-dependent signalling functions, including growth factor and Sonic hedgehog signalling. To better understand the developmental impact of ATR loss of function, we also used zebrafish as a model. Zebrafish embryos depleted of Atr resembled ATR-SS morphology, showed a modest but statistically significant reduction in cilia length and other morphological features indicative of cilia dysfunction. Additionally, they displayed defects in left-right asymmetry including ambiguous expression of southpaw, incorrectly looped hearts and randomized localization of internal organs including the pancreas, features typically conferred by cilia dysfunction. Our findings reveal a novel role for ATR in cilia signalling distinct from its canonical function during replication and strengthen emerging links between cilia function and development. PMID:26908596

  11. ATR promotes cilia signalling: links to developmental impacts.

    PubMed

    Stiff, Tom; Casar Tena, Teresa; O'Driscoll, Mark; Jeggo, Penny A; Philipp, Melanie

    2016-04-15

    Mutations inATR(ataxia telangiectasia and RAD3-related) cause Seckel syndrome (ATR-SS), a microcephalic primordial dwarfism disorder. Hitherto, the clinical manifestation of ATR deficiency has been attributed to its canonical role in DNA damage response signalling following replication fork stalling/collapse. Here, we show that ATR regulates cilia-dependent signalling in a manner that can be uncoupled from its function during replication. ATR-depleted or patient-derived ATR-SS cells form cilia of slightly reduced length but are dramatically impaired in cilia-dependent signalling functions, including growth factor and Sonic hedgehog signalling. To better understand the developmental impact of ATR loss of function, we also used zebrafish as a model. Zebrafish embryos depleted of Atr resembled ATR-SS morphology, showed a modest but statistically significant reduction in cilia length and other morphological features indicative of cilia dysfunction. Additionally, they displayed defects in left-right asymmetry including ambiguous expression ofsouthpaw, incorrectly looped hearts and randomized localization of internal organs including the pancreas, features typically conferred by cilia dysfunction. Our findings reveal a novel role for ATR in cilia signalling distinct from its canonical function during replication and strengthen emerging links between cilia function and development. PMID:26908596

  12. Classification of agents using Syrian hamster embryo (SHE) cell transformation assay (CTA) with ATR-FTIR spectroscopy and multivariate analysis.

    PubMed

    Ahmadzai, Abdullah A; Trevisan, Jlio; Pang, Weiyi; Riding, Matthew J; Strong, Rebecca J; Llabjani, Valon; Pant, Kamala; Carmichael, Paul L; Scott, Andrew D; Martin, Francis L

    2015-09-01

    The Syrian hamster embryo (SHE) cell transformation assay (pH 6.7) has a reported sensitivity of 87% and specificity of 83%, and an overall concordance of 85% with in vivo rodent bioassay data. To date, the SHE assay is the only in vitro assay that exhibits multistage carcinogenicity. The assay uses morphological transformation, the first stage towards neoplasm, as an endpoint to predict the carcinogenic potential of a test agent. However, scoring of morphologically transformed SHE cells is subjective. We treated SHE cells grown on low-E reflective slides with 2,6-diaminotoluene, N-nitroso-N-ethylnitroguanidine, N-nitroso-N-methylurea, N-nitroso-N-ethylurea, EDTA, dimethyl sulphoxide (DMSO; vehicle control), methyl methanesulfonate, benzo[e]pyrene, mitomycin C, ethyl methanesulfonate, ampicillin or five different concentrations of benzo[a]pyrene. Macroscopically visible SHE colonies were located on the slides and interrogated using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy acquiring five spectra per colony. The acquired IR data were analysed using Fisher's linear discriminant analysis (LDA) followed by principal component analysis (PCA)-LDA cluster vectors to extract major and minor discriminating wavenumbers for each treatment class. Each test agent vs. DMSO and treatment-induced transformed cells vs. corresponding non-transformed were classified by a unique combination of major and minor discriminating wavenumbers. Alterations associated with Amide I, Amide II, lipids and nucleic acids appear to be important in segregation of classes. Our findings suggest that a biophysical approach of ATR-FTIR spectroscopy with multivariate analysis could facilitate a more objective interrogation of SHE cells towards scoring for transformation and ultimately employing the assay for risk assessment of test agents. PMID:25925069

  13. Hyperspectral Sensing for Turbid Water Quality Monitoring in Freshwater Rivers: Empirical Relationship between Reflectance and Turbidity and Total Solids

    PubMed Central

    Wu, Jiunn-Lin; Ho, Chung-Ru; Huang, Chia-Ching; Srivastav, Arun Lal; Tzeng, Jing-Hua; Lin, Yao-Tung

    2014-01-01

    Total suspended solid (TSS) is an important water quality parameter. This study was conducted to test the feasibility of the band combination of hyperspectral sensing for inland turbid water monitoring in Taiwan. The field spectral reflectance in the Wu river basin of Taiwan was measured with a spectroradiometer; the water samples were collected from the different sites of the Wu river basin and some water quality parameters were analyzed on the sites (in situ) as well as brought to the laboratory for further analysis. To obtain the data set for this study, 160 in situ sample observations were carried out during campaigns from August to December, 2005. The water quality results were correlated with the reflectivity to determine the spectral characteristics and their relationship with turbidity and TSS. Furthermore, multiple-regression (MR) and artificial neural network (ANN) were used to model the transformation function between TSS concentration and turbidity levels of stream water, and the radiance measured by the spectroradiometer. The value of the turbidity and TSS correlation coefficient was 0.766, which implies that turbidity is significantly related to TSS in the Wu river basin. The results indicated that TSS and turbidity are positively correlated in a significant way across the entire spectrum, when TSS concentration and turbidity levels were under 800 mg·L−1 and 600 NTU, respectively. Optimal wavelengths for the measurements of TSS and turbidity are found in the 700 and 900 nm range, respectively. Based on the results, better accuracy was obtained only when the ranges of turbidity and TSS concentration were less than 800 mg·L−1 and less than 600 NTU, respectively and used rather than using whole dataset (R2 = 0.93 versus 0.88 for turbidity and R2 = 0.83 versus 0.58 for TSS). On the other hand, the ANN approach can improve the TSS retrieval using MR. The accuracy of TSS estimation applying ANN (R2 = 0.66) was better than with the MR approach (R2 = 0.58), as expected due to the nonlinear nature of the transformation model. PMID:25460816

  14. Hyperspectral sensing for turbid water quality monitoring in freshwater rivers: Empirical relationship between reflectance and turbidity and total solids.

    PubMed

    Wu, Jiunn-Lin; Ho, Chung-Ru; Huang, Chia-Ching; Srivastav, Arun Lal; Tzeng, Jing-Hua; Lin, Yao-Tung

    2014-01-01

    Total suspended solid (TSS) is an important water quality parameter. This study was conducted to test the feasibility of the band combination of hyperspectral sensing for inland turbid water monitoring in Taiwan. The field spectral reflectance in the Wu river basin of Taiwan was measured with a spectroradiometer; the water samples were collected from the different sites of the Wu river basin and some water quality parameters were analyzed on the sites (in situ) as well as brought to the laboratory for further analysis. To obtain the data set for this study, 160 in situ sample observations were carried out during campaigns from August to December, 2005. The water quality results were correlated with the reflectivity to determine the spectral characteristics and their relationship with turbidity and TSS. Furthermore, multiple-regression (MR) and artificial neural network (ANN) were used to model the transformation function between TSS concentration and turbidity levels of stream water, and the radiance measured by the spectroradiometer. The value of the turbidity and TSS correlation coefficient was 0.766, which implies that turbidity is significantly related to TSS in the Wu river basin. The results indicated that TSS and turbidity are positively correlated in a significant way across the entire spectrum, when TSS concentration and turbidity levels were under 800 mgL(-1) and 600 NTU, respectively. Optimal wavelengths for the measurements of TSS and turbidity are found in the 700 and 900 nm range, respectively. Based on the results, better accuracy was obtained only when the ranges of turbidity and TSS concentration were less than 800 mgL(-1) and less than 600 NTU, respectively and used rather than using whole dataset (R(2) = 0.93 versus 0.88 for turbidity and R(2) = 0.83 versus 0.58 for TSS). On the other hand, the ANN approach can improve the TSS retrieval using MR. The accuracy of TSS estimation applying ANN (R(2) = 0.66) was better than with the MR approach (R(2) = 0.58), as expected due to the nonlinear nature of the transformation model. PMID:25460816

  15. Deposition from dopamine solutions at Ge substrates: an in situ ATR-FTIR study.

    PubMed

    Müller, Martin; Kessler, Bernd

    2011-10-18

    Deposition from dopamine (DA) solutions at germanium (Ge) model substrates was monitored under stationary conditions using surface sensitive in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR spectra of the interfacial organic layer formed upon contact of TRIS buffered aqueous DA solutions to a Ge internal reflection element (IRE) showed conveniently strong diagnostic IR absorption bands, which were increasing with deposition time up to at least 6 h. Comparison of IR spectra of unreacted pristine DA, surface reacted, and bulk reacted material confirmed chemical reactions of DA to a polymerizate according to the literature. The found IR bands could be assigned to aromatic as well as C-O single bond moieties. The kinetic courses of the diagnostic band integrals showed an initial increase and saturation of the deposition after around 300 min, which could be empirically represented by an exponential damping function revealing a rather small kinetic constant. Highest deposition levels were found at pH = 8.5 (TRIS buffer or NaOH) in contrast to pH = 6.2, where no deposition occurred. Minor deposition was found in the presence of salt or at ZnSe instead of Ge due to the absence of reactive hydroxyl groups. The concentration dependence of DA deposition showed an initial increase and a saturation beginning at around 0.4 mg/mL (0.0022 M), where around 50 nm thick films featuring granular surface morphologies are formed. The adsorbed species are suggested to be smaller bulk reacted DA polymerizate particles with reactive end groups. Rinsing the formed films by pure TRIS buffer resulted in a time dependent release of deposited organic material by ≈23%, which could be represented by an exponential decay function. A saturation of the release after around 100 min and a larger kinetic constant compared to deposition could be determined. The released material is suggested to be larger aggregated bulk reacted DA polymerizate particles loosely bound to the surface by weak interaction forces. PMID:21866968

  16. 75 FR 8476 - Airworthiness Directives; ATR-GIE Avions de Transport Régional Model ATR42 and ATR72 Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-25

    ..., amendment 39-16159 (75 FR 221, January 5, 2010), on December 28, 2009. That AD applies to certain portable...'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and 3. Will not have... Transport R gional Model ATR42 and ATR72 Airplanes AGENCY: Federal Aviation Administration (FAA),...

  17. [Estimating total nitrogen content in reclaimed water based on hyperspectral reflectance information from emergent plants: a case study of Mencheng Lake Wetland Park in Beijing, China].

    PubMed

    Liu, Hui; Gong, Zhao-ning; Zhao, Wen-ji

    2014-12-01

    Hyperspectral reflectance information is a crucial method to detect total nitrogen content in plant leaves, meanwhile, vegetation nitrogen content has a strong relationship with nitrogen in water. Taking Mencheng Lake Wetland Park supplied with reclaimed water as study area, the vegetation hyperspectral data (Phragmites australis and Typha angustifolia), and the content of total nitrogen in water were detected to investigate the feasibility of estimating total nitrogen content in reclaimed water based on hyperspectral reflectance information from emergent plants. We established simple linear regression model, stepwise multiple linear regression model and partial least square regression model based on four hyperspectral indices (spectral indices, normalized difference indices, trilateral parameters, absorption feature parameters), respectively. The accuracy of these models was coefficient of determination (R2) and root mean square error (RMSE). The results showed that stepwise multiple linear regression model and partial least square regression model predicted more accurately than simple linear regression model, and the accuracy of prediction models based on P. australis reflectance spectra was higher than those on T. angustifolia. Partial least square regression model was the most useful explorative tool for unraveling the relationship between spectral reflectance of P. australis and total nitrogen content in water with R2 of 0.854 and RMSE of 0.647. 500-700 nm was the best band range for detecting water total nitrogen content. The reflectance ratio of green peak and red valley could be effectively predicted by the absorption feature parameters. PMID:25876415

  18. Combining Mass Spectrometry and ATR-FTIR Spectroscopy to Study Phase, Diffusion and Composition of Secondary Organic Aerosol from the Ozonolysis of ?-pinene

    NASA Astrophysics Data System (ADS)

    Perraud, V. M.; Finlayson-Pitts, B. J.; Waring-Kidd, C.

    2014-12-01

    Secondary organic aerosol (SOA) is ubiquitous in the atmosphere and composes a large fraction of the total aerosol budget. Recent reports from field measurements and laboratory studies show that some SOA particles are better represented by a semi-solid low viscosity tar-like material rather than a ideal liquid often assumed in regional and global models. Characterizing the phase of SOA is crucial to understanding how particles interact with trace gases and how it ultimately impacts their growth and evolution in the atmosphere. We report here laboratory studies carried out in the unique UCI large-volume, slow-flow, aerosol flow reactor. Particles from the ozonolysis of a-pinene were formed at various relative humidities (RH from < 3% to 90%) and collected onto a custom ATR-FTIR impactor. The observed impaction pattern provided insights into changes in phase/viscosity of the SOA as a function of relative humidity. In addition, attenuated total reflectance FTIR and mass spectrometry measurements provided information on simultaneous changes on composition. Application of ATR-FTIR combined with PTR-MS provided additional data on the volatility of the SOA at room temperature and diffusion coefficients of two key components pinonaldehyde and acetic acid present in the SOA. Implication for modeling the growth and ultimately the lifetime of SOA in the atmosphere will be discussed.

  19. Determination of metal-cofactors in enzyme complexes by total-reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Wittershagen, A.; Rostam-Khani, P.; Klimmek, O.; Gro, R.; Zickermann, V.; Zickermann, I.; Gemeinhardt, S.; Krger, A.; Ludwig, B.; Kolbesen, B. O.

    1997-07-01

    The determination of metal-cofactors and their molar concentrations is an important requirement for the characterisation of metalloproteins and a challenge regarding the capabilities of trace analytical methods. In this respect, total-reflection X-ray fluorescence spectrometry offers many advantages for the determination of trace elements in enzymes, as compared to other well known analytical techniques such as flame atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry (ICP-AES), because of the significantly smaller amounts of sample required. Without any decomposition, elements like P, S, Fe, Ni, Cu, Zn, Mn and Mo could be determined with high accuracy, in spite of the large bio-organic matrix. The enzymes (polysulphide reductase and hydrogenase of the rumen bacterium Wolinella succinogenes, and the cytochrome c oxidase and quinol oxidase of the soil bacterium Paracoccus denitrificans) were transferred from their usual salt-buffer into a solution of 100 mmol l -1 tris(hydroxymethyl)aminomethane (tris)-acetate containing an appropriate detergent. By this procedure, an improved signal-to-noise ratio is obtained. The polysulphide reductase was found to contain copper as a hitherto existing unknown cofactor. The enzyme contains a stretch of amino acids that are typical of copper proteins and thus confirm the presence of this element. Furthermore, the data concerning cytochrome c oxidase from Paracoccus denitrificans are in good agreement with published values obtained by ICP-AES. Also, results from measurements with the quinol oxidase from the same bacterium agree with the expected values. The investigations lead to the conclusion that the method is well suited to the quantitative determination of metals in enzymes, in particular their molar fractions, and requires only small amounts of the biological sample without any extensive pretreatment.

  20. Type-II Superlattices and Variable Overlap Superlattices in Total Internal Reflection Switches for the Longwave Infrared

    NASA Astrophysics Data System (ADS)

    Youngdale, E. R.; Meyer, J. R.; Hoffman, C. A.; Bartoli, F. J.; Wang, W. I.

    We derive explicit criteria for the properties required of a semiconductor nonlinear medium suitable for use in all-optical switching devices employing total internal reflection. Transmission as a function of laser intensity and film thickness has been calculated using a realistic model for penetration of the evanescent beam under TIR conditions. Requirements based on these results include a large nonlinear refractive index, large index change at saturation and small absorption coefficient. We show that unlike previously-studied semimetals and narrow-gap semiconductors, Type-II superlattices such as InAs-GaSb and variable-overlap superlattices (variants of Type-II which include a spacer between the layer containing the conduction-band minimum and that containing the valence band maximum) such as InAs-AlSb-GaSb hold prospects for satisfying all of these requirements simultaneously. As the free carrier lifetime will have a crucial influence on device performance, we have initiated a systematic experimental study of electron-hole recombination in InAs-based superlattices. From degenerate and nondegenerate four-wave mixing experiments, we have also determined nonlinear optical coefficients as a function of difference frequency and intensity. An InAs-GaSb superlattice has been found to display a refractive index change of ? 0.1, as well as device figures of merit which slightly surpasses any previously reported for weakly-saturating nonlinearities at CO2 wavelengths. It is anticipated that future experiments on Type-II superlattices with longer lifetimes may yield nearly two orders of magnitude additional improvement in the nonlinear refractive index.

  1. Total reflection X-ray fluorescence analysis of oral fluids of women affected by osteoporosis and osteopenia

    NASA Astrophysics Data System (ADS)

    Snchez, Hctor Jorge; Valentinuzzi, Mara Cecilia; Grenn, Miram; Abraham, Jos

    2008-12-01

    Osteoporosis is a disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures; the early stage of decreased bone density is called osteopenia. More than 200 million people are affected and about 50% of post-menopausic women are expected to develop the disease. Osteoporosis, osteopenia and periodontal disease have in common several risk factors, being hyperthyroidism and smoking habits the most important ones. There is scarce information in the literature about the association between periodontal disease and osteoporosis and/or osteopenia. Some works suggest that osteoporotic women are susceptible to a higher loss of periodontal insertion, alveolar bones, and teeth. Thirty adult post-menopausic women were studied; some of them were healthy (control group) and the rest of them were undergoing some stage of osteoporosis or osteopenia. All the subjects were healthy, non-smokers, not having dental implants, and with communitarian periodontal index higher than 1(CPI > 1). Samples of saliva and gingival crevice fluid were extracted with calibrated micro-capillaries and deposited on Si reflectors. Known amounts of Ga were added to the samples in order to act as internal standard for quantification by the total reflection x-ray fluorescence technique. Experimental concentrations of several elements (P, S, Cl, K, Ca, Cr, Fe, NI, Cu, and Zn) were determined. The concentration of some elements in saliva showed different behavior as compared to gingival crevice fluid. Some critical elements of bone composition, such as Ca and Zn, present very distinguishable behavior. Improvements in the statistics are required for a better assessment of a routine method and to establish some correlation with periodontal disease. TXRF seems to be a promising method to evaluate the evolution of osteoporosis.

  2. Zinc and cadmium accumulation in single zebrafish ( Danio rerio) embryos A total reflection X-ray fluorescence spectrometry application

    NASA Astrophysics Data System (ADS)

    Mages, Margarete; Bandow, Nicole; Kster, Eberhard; Brack, Werner; von Tmpling, Wolf

    2008-12-01

    Trace metals such as Cadmium (Cd) and Zinc (Zn) are known to exhibit adverse effects on many aquatic organisms including early life stages of fish. In contact with contaminated sediment, fish eggs and embryos may be exposed to metals via the water phase as well as via direct contact with contaminated particles. This may result in body burdens that are difficult to predict and may vary according to individual micro scale exposure conditions. The highly sensitive total reflection X-ray fluorescence spectrometry (TXRF) may provide a tool to analyse individual embryos for internal contaminant concentrations and thus helps to develop a better understanding of dose-response relationships. To test this hypothesis, embryos of Danio rerio were exposed to Cd and Zn spiked sediment in different treatments applying an ion exchange resin for modification of bioavailable concentrations. The TXRF analysis indicated individual embryos with dramatically enhanced exposure compared to other individuals despite uniform exposure conditions on a macro scale. Ion exchanger reduced embryo Zn concentrations to values close to control value with a comparably low standard deviation. Cadmium concentrations in embryos were in the range of 4000 to 7000 g/g with a median of 5740 g/g. A commercial ion exchanger reduced individual body burdens by a factor 50 to 100. Individual peak body burdens of up to 3160 g/g were accompanied by reduced weight of the fish eggs due to early death i.e. coagulation. The investigation of exposure and effects on an individual-based scale may significantly help to reduce uncertainty and inconsistencies occurring in conventional analysis of pooled fish embryo samples.

  3. Application of CO2 Snow Jet Cleaning in Conjunction with Laboratory Based Total Reflection X-Ray Fluorescence

    NASA Technical Reports Server (NTRS)

    Schmeling, M.; Burnett, D. S.; Allton, J. H.; Rodriquez, M.; Tripa, C. E.; Veryovkin, I. V.

    2013-01-01

    The Genesis mission was the first mission returning solar material to Earth since the Apollo program [1,2]. Unfortunately the return of the space craft on September 8, 2004 resulted in a crash landing, which shattered the samples into small fragments and exposed them to desert soil and other debris. Thus only small fragments of the original collectors are available, each having different degrees of surface contamination. Thorough surface cleaning is required to allow for subsequent analysis of solar wind material embedded within. An initial cleaning procedure was developed in coordination with Johnson Space Center which focused on removing larger sized particulates and a thin film organic contamination acquired during collection in space [3]. However, many of the samples have additional residues and more rigorous and/or innovative cleaning steps might be necessary. These cleaning steps must affect only the surface to avoid leaching and re-distribution of solar wind material from the bulk of the collectors. To aid in development and identification of the most appropriate cleaning procedures each sample has to be thoroughly inspected before and after each cleaning step. Laboratory based total reflection X-ray fluorescence (TXRF) spectrometry lends itself to this task as it is a non-destructive and surface sensitive analytical method permitting analysis of elements from aluminum onward present at and near the surface of a flat substrate [4]. The suitability of TXRF has been demonstrated for several Genesis solar wind samples before and after various cleaning methods including acid treatment, gas cluster ion beam, and CO2 snow jet [5 - 7]. The latter one is non-invasive and did show some promise on one sample [5]. To investigate the feasibility of CO2 snow jet cleaning further, several flown Genesis samples were selected to be characterized before and after CO2 snow application with sample 61052 being discussed below.

  4. Dopamine and amphetamine rapidly increase dopamine transporter trafficking to the surface: live cell imaging using total internal reflection fluorescence microscopy

    PubMed Central

    Furman, Cheryse A.; Chen, Rong; Guptaroy, Bipasha; Zhang, Minjia; Holz, Ronald W.; Gnegy, Margaret

    2009-01-01

    Rapid treatment (1 min) of rat striatal synaptosomes with low dose amphetamine increases surface expression of the dopamine transporter (DAT). Using mouse neuroblastoma N2A cells stably transfected with GFP-DAT we demonstrate the real-time substrate-induced rapid trafficking of DAT to the plasma membrane using total internal reflection fluorescence microscopy (TIRFM). Both the physiological substrate, dopamine, and amphetamine began to increase surface DAT within 10 sec of drug addition and steadily increased surface DAT until removal 2 min later. The substrate-induced rise in surface DAT was dose-dependent, was blocked by cocaine and abated after drug removal. While individual vesicle fusion was not visually detectable, exocytosis of DAT was blocked using both tetanus neurotoxin and botulinum neurotoxin C to cleave SNARE proteins. Notably, the dopamine-induced increase in surface DAT was cocaine-sensitive but D2-receptor independent. TIRFM data were confirmed in human DAT-N2A cells using biotinylation and similar effects were detected in rat striatal synaptosomes. A specific inhibitor of protein kinase C-? blocked the substrate-mediated increase in surface DAT in both DAT-N2A cells and rat striatal synaptosomes. These data demonstrate that the physiological substrate, dopamine, and amphetamine rapidly increase the trafficking of DAT to the surface by a mechanism dependent upon SNARE proteins and protein kinase C-? but independent of dopamine D2 receptor activation. Importantly, this study suggests that the reuptake system is poised to rapidly increase its function upon dopamine secretion in order to tightly regulate dopaminergic neurotransmission. PMID:19279270

  5. Cold plasma ashing improves the trace element detection of single Daphnia specimens by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Woelfl, Stefan; Mages, Margarete; Encina, Francisco

    2003-12-01

    The recently developed dry method for the element determination of single freshwater microcrustacean specimens ( Daphnia) using total reflection X-ray fluorescence (TXRF) spectrometry showed that inhomogeneities of the biological material on the glass carriers resulted in some cases in high background and hampered the detection of certain trace elements (e.g. Cr, Ni). The aim of this study was to test how inhomogeneities of the biological material can be reduced using cold plasma ashing (CPA) techniques. For that, single specimens of the microcrustacean Daphnia pulex prepared according to the dry method were measured by TXRF before and after CPA. To determine the efficiency of the removal of organic matrix, the background and signal-to-background relationship of 28 samples were analyzed. The results showed (1) a highly significant reduction of the background by CPA fluctuating between 26 and 46% (all elements) and (2) a significant increase of the signal-to-background relationship by the factor 1.5-2.5 (all elements) and a much better detection of Cr, Pb, As and Se. The element concentrations (with exception of Cr, Ni and Pb) after ashing were in the same range or slightly higher than that before ashing. No significant differences between the two treatments were observed for Mn, As, Pb, Se (November), Sr (November), Cr (March) and Pb (March). The element concentration of P, K, Ca, Cu, Zn, Cr (November), Fe and Rb were significantly higher after ashing. In general, they increased by 1.5-13.6% and were highest for Rb (March) and P (November). In contrast, the element concentration of Ni and Cr (only March) decreased significantly after ashing (Ni: 91.6-92.1%, Cr: 91.3%). We recommend the use of CPA for biological material in the microgram-range as a routine method for TXRF analysis, especially when trace elements in minute concentrations are of interest.

  6. Determination of trace elements in freshwater rotifers and ciliates by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Woelfl, S.; Óvári, M.; Nimptsch, J.; Neu, T. R.; Mages, M.

    2016-02-01

    Element determination in plankton is important for the assessment of metal contamination of aquatic environments. Until recently, it has been difficult to determine elemental content in rotifers or ciliates derived from natural plankton samples because of the difficulty in handling and separation of these fragile organisms. The aim of this study was to evaluate methods for separation of rotifers and large ciliates from natural plankton samples (μg range dry weight) and subsequent analysis of their elemental content using total-reflection X-ray fluorescence spectrometry (TXRF). Plankton samples were collected from different aquatic environments (three lakes, one river) in Chile, Argentina and Hungary. From one to eighty specimens of five rotifer species (Brachionus calyciflorus, Brachionus falcatus, Asplanchna sieboldii, Asplanchna sp., Philodina sp.) and four to twelve specimens of one large ciliate (Stentor amethystinus) were prepared according to the dry method originally developed for microcrustaceans, and analysed by TRXF following in situ microdigestion. Our results demonstrated that it possible to process these small and fragile organisms (individual dry mass: 0.17-9.39 μg ind- 1) via careful washing and preparation procedures. We found species-dependent differences of the element mass fractions for some of the elements studied (Cr, Mn, Fe, Ni, Cu, Zn, As, Pb), especially for Cu, Fe and Mn. One large rotifer species (A. sieboldii) also showed a negative correlation between individual dry weight and the element content for Pb, Ni and Cr. We conclude that our application of the in situ microdigestion-TRXF method is suitable even for rotifers and ciliates, greatly expanding the possibilities for use of plankton in biomonitoring of metal contamination in aquatic environments.

  7. Oriented 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine/ganglioside membranes: a Fourier transform infrared attenuated total reflection spectroscopic study. Band assignments; orientational, hydrational, and phase behavior; and effects of Ca2+ binding.

    PubMed Central

    Mller, E; Giehl, A; Schwarzmann, G; Sandhoff, K; Blume, A

    1996-01-01

    Fourier transform infrared (FTIR) attenuated total reflection (ATR) spectroscopy was used to elucidate the hydration behavior and molecular order of phospholipid/ganglioside bilayers. We examined dry and hydrated films of the gangliosides GM1, deacetyl-GM1, lyso-GM1, deacetyllyso-GM1, and GM3 and oriented mixed films of these gangliosides with 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) using polarized light. Analysis of the amide I frequencies reveals that the amide groups are involved in intermolecular interactions via hydrogen bonds of varying strengths. The tilt angle of the acyl chains of the lipids in mixed films was determined as a function of ganglioside structure. Deacetylation of the sialic acid in the headgroup has a stronger influence on the tilt angle than the removal of the ganglioside fatty acid. The phase behavior was examined by FTIR ATR spectroscopy and by differential scanning calorimetry (DSC) measurements on lipid suspensions. At the same molar concentration, lyso-gangliosides have less effect on changes of transition temperature compared to the double-chain analogs. Distinct differences in the amide band shapes were observed between mixtures with lyso-gangliosides and normal double-chain gangliosides. Determined from the dicroic ratio RATR, the orientation of the COO- group in all DMPC/ganglioside mixtures was found to be relatively fixed with respect to the membrane normal. In 4:1 mixtures of DMPC with GM1 and deacetyl-GM1, the binding of Ca2+ leads to a slight decrease in chain tilt in the gel phase, probably caused by a dehydration of the membrane-water interface. In mixtures of DMPC with GM3 and deacetyl-lyso-GM1, a slight increase in chain tilt is observed. The chain tilt in DMPC/lyso-GM1 mixtures is unchanged. Analysis of the COO- band reveals that Ca2+ does not bind to the carboxylate group of the sialic acid of GM1 and deacetyl-GM1, the mixtures in which a decrease in chain tilt was observed. Binding to the sialic acid was only observed for mixtures of DMPC with GM3, lyso-GM1, and deacetyl-lyso-GM1. Ca2+ obviously accumulates at the bilayer-water interface and leads to partial dehydration of the headgroup region in the gel as well as in the liquid-crystalline phase. This can be concluded from the changes in the amide I band shapes. With the exception of DMPC/deacetyl-GM1, the effects on the ester C==O bands are small. The addition of Ca2+ has minor effects on the phase behavior, with the exception of the DMPC/GM1 mixture. PMID:8874015

  8. Computer analysis of ATR-FTIR spectra of paint samples for forensic purposes

    NASA Astrophysics Data System (ADS)

    Szafarska, Małgorzata; Woźniakiewicz, Michał; Pilch, Mariusz; Zięba-Palus, Janina; Kościelniak, Paweł

    2009-04-01

    A method of subtraction and normalization of IR spectra (MSN-IR) was developed and successfully applied to extract mathematically the pure paint spectrum from the spectrum of paint coat on different bases, both acquired by the Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) technique. The method consists of several stages encompassing several normalization and subtraction processes. The similarity of the spectrum obtained with the reference spectrum was estimated by means of the normalized Manhattan distance. The utility and performance of the method proposed were tested by examination of five different paints sprayed on plastic (polyester) foil and on fabric materials (cotton). It was found that the numerical algorithm applied is able - in contrast to other mathematical approaches conventionally used for the same aim - to reconstruct a pure paint IR spectrum effectively without a loss of chemical information provided. The approach allows the physical separation of a paint from a base to be avoided, hence a time and work-load of analysis to be considerably reduced. The results obtained prove that the method can be considered as a useful tool which can be applied to forensic purposes.

  9. ATR-FTIR spectroscopic studies of boric acid adsorption on hydrous ferric oxide

    NASA Astrophysics Data System (ADS)

    Peak, Derek; Luther, George W.; Sparks, Donald L.

    2003-07-01

    Boron is an important micronutrient for plants, but high B levels in soils are often responsible for toxicity effects in plants. It is therefore important to understand reactions that may affect B availability in soils. In this study, Attenuated Total Reflectance Fourier transform Infrared (ATR-FTIR) spectroscopy was employed to investigate mechanisms of boric acid (B(OH) 3) and borate (B(OH) 4-) adsorption on hydrous ferric oxide (HFO). On the HFO surface, boric acid adsorbs via both physical adsorption (outer-sphere) and ligand exchange (inner-sphere) reactions. Both trigonal (boric acid) and tetrahedral (borate) boron are complexed on the HFO surface, and a mechanism where trigonal boric acid in solution reacts to form either trigonal or tetrahedral surface complexes is proposed based upon the spectroscopic results. The presence of outer-sphere boric acid complexes can be explained based on the Lewis acidity of the B metal center, and this complex has important implications for boron transport and availability. Outer-sphere boric acid is more likely to leach downward in soils in response to water flow. Outer-sphere boron would also be expected to be more available for plant uptake than more strongly bound boron complexes, and may more readily return to the soil solution when solution concentrations decrease.

  10. In situ ATR-FTIR study of the early stages of fly ash geopolymer gel formation.

    PubMed

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

    2007-08-14

    The kinetics of geopolymer formation are monitored using a novel in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic technique. Reaction rates are determined from the intensity variation of the bands related to the geopolymer gel network and the unreacted fly ash particles. Comparison with deuterated geopolymer samples provides critical information regarding peak assignments. An initial induction (lag) period is observed to occur for hydroxide-activated geopolymers, followed by gel evolution according to an approximately linear reaction profile. The length of the lag period is reduced by increasing the concentration of NaOH. An increase in the rate of network formation also occurs with increasing NaOH concentration up to a maximum point, beyond which an increased NaOH concentration leads to a reduced rate of network formation. This trend is attributed to the competing effects of increased alkalinity and stronger ion pairing with an increase in NaOH concentration. In situ analysis also shows that the rate of fly ash dissolution is similar for all moderate- to high-alkali geopolymer slurries, which is attributed to the very highly water-deficient nature of these systems and is contrary to predictions from classical glass dissolution chemistry. This provides for the first time detailed kinetic information describing fly ash geopolymer formation kinetics. PMID:17658864

  11. Structural characterization of nylon 7 by solid-state NMR, DSC, and ATR-FTIR

    NASA Astrophysics Data System (ADS)

    Johnson, C. G.; Mathias, L. J.

    1993-06-01

    Samples of commercial nylon 7 were given different thermal or precipitation histories. Structure and crystallinity were followed by DSC, solid-state NMR, and attenuated total reflectance FTIR (ATR-FTIR). Delta H and T(sub m) values ranged from 52 to 93 J/g and 228 to 242 C, respectively. Surprisingly, annealing did not give material with the greatest delta H although it possessed the highest melting point. Solid-state C-13 and N-15 NMR methods were used to observe the amorphous and crystalline fractions. For example, the amide nitrogens show resonances near 86.5 ppm in amorphous domains, near 84 ppm in alpha-crystals, and near 89 ppm in gamma-crystals. N-15 CP/MAS spectra of solution cast samples contained peaks consistent with all three domains in various intensity ratios but with the gamma-peak being the most intense for most samples. Solid-state C-13 spectra contained peaks which supported the presence of these phases but with the alpha-phase peaks predominating.

  12. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism.

    PubMed

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-02-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm(-1) that originates from the pyranose ring structure of glucose gave measurement errors less than 20%. PMID:26977373

  13. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism

    PubMed Central

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-01-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm−1 that originates from the pyranose ring structure of glucose gave measurement errors less than 20%. PMID:26977373

  14. [Spectral analysis of ball pen script by FTIR microscope with ATR objective].

    PubMed

    Huang, Tao-Hong; Wu, Tian-Ming

    2007-11-01

    Inspection of ball pen script is very important in public security and justice field. It is difficult to get a good spectrum directly by infrared microscope reflectance mode because of low reflectivity of paper and dark gray in color. The best way to measure low reflectivity sample is by infrared microscope with ATR objective method. Measurement with the microscopic ATR method involves bringing the trace of ball pen ink into contact with the prism. By this method, some mixed spectra of ball pen ink and paper fiber were obtained from one of the actual sample. The spectrum of the paper was subtracted from those mixed spectra and a pure spectrum of the ball pen ink was obtained. In this spectrum, three strong peaks were found 1 581, 1 361 and 1 172 cm(-1) respectively, all from crystal violet, a typical triphenylmethane pigment. Another strong peak at 1 724 cm(-1) is contributed by carbonyl vibration from oil reagent alkyd. A 3D graph, showing the distribution of peak 1 581 cm(-1) in this area, was set up by using mapping software. In the 3D distribution graph, the figure of ball pen trace vividly appeared. This infrared microscope ATR method makes it available to nondestructively inspect original ball pen script. PMID:18260394

  15. Adaptive configuration and control in an ATR system

    NASA Astrophysics Data System (ADS)

    Roberts, Barry A.; Au, Wing K.

    1995-06-01

    Today's ATR is constructed via inefficient and suboptimal system configuration and training. The process of configuring an ATR is currently very labor intensive, subjective, and inaccurate, as is the process of training an ATR for a particular mission. To cure this deficiency, what is desired is an automated method of configuration and training which is capable of searching the N-dimensional space of modules, algorithms, and parameter values to produce ATR algorithm suites which perform best in each trained scenario. Also, today's ATR is only capable of a limited amount of adaptation to sensed (or otherwise obtained) changes in the environment. To improve the adaptibility of ATR processing and thereby improve accuracy and robustness, what is desired is a high-level control structure which enables system adaptation via changes in parameter values and changes in algorithms (at the component and at the 'suite' level). The Honeywell effort is producing a system for Adaptive Configuration and Control (ACC) of an ATR system which addresses the above described problems. The software system is using the machine learning technique of Genetic Algorithms to autonomously and optimally perform configuration and training and it is using case-based reasoning to provide run-time configuration and control of the ATR system. This paper provides an overview of the ACC system, describes its operation, and describes the benefits it provides to ATR systems.

  16. Advanced miniature processing handware for ATR applications

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin (Inventor); Daud, Taher (Inventor); Thakoor, Anikumar (Inventor)

    2003-01-01

    A Hybrid Optoelectronic Neural Object Recognition System (HONORS), is disclosed, comprising two major building blocks: (1) an advanced grayscale optical correlator (OC) and (2) a massively parallel three-dimensional neural-processor. The optical correlator, with its inherent advantages in parallel processing and shift invariance, is used for target of interest (TOI) detection and segmentation. The three-dimensional neural-processor, with its robust neural learning capability, is used for target classification and identification. The hybrid optoelectronic neural object recognition system, with its powerful combination of optical processing and neural networks, enables real-time, large frame, automatic target recognition (ATR).

  17. A physically-based model for Total Suspended Matter retrieval via hyperspectral reflectance inversion in turbid waters

    NASA Astrophysics Data System (ADS)

    Pitarch, Jaime; Kawka, Marcin; Odermatt, Daniel; West, Alfred

    2013-04-01

    We present an approach to estimate the vertical distribution of total suspended matter (TSM) from above-surface radiometric measurements in inland waters. To obtain the needed ground-truth data, a field campaign was carried out in Lake Constance on May 25, 2012. In spring, Lake Constance receives massive input of suspended particles due to a discharge peak from the Alpine Rhine caused by intensive snow melting. Due to density differences between lake's and river's waters, and also to lake currents, TSM shows with complicated horizontal and vertical variation. We made a transect consisting of 26 points, covering the east part of the lake. We measured light transmissivity along a 10 cm path at the wavelength 650 nm, which was converted to beam attenuation c(z) (1/m). Additionally, we made gravimetric measurements of TSM from surface water TSM(0), which ranged between 0 and 14 mg/l. The regression line c(0)-TSM(0) (r2=0.96) was used as a calibration curve to build TSM(z).Chlorophyll-a was measured with a Trilux fluorometer, from Chelsea Technologies Group. Absorption by CDOM was supposed known, having exponential decay with depth and wavelength. We also took above-surface radiometric measurements with a hand-held spectrometer. Using optical theory, we modelled the water inherent optical properties (IOPs) as formed by four components: pure water, dissolved coloured organic matter (CDOM), chlorophyll-bearing particles and mineral particles. Radiative transfer code (Hydrolight) was used to model the light field. As a derived quantity, the simulated remote sensing reflectance was matched to the measured one. The possibilities of this technique are evaluated and discussed. In particular, how much vertical information can be retrieved from above-surface measurements, having also the physical limitation of light penetration. This work is part of the validation activities for the FP-7 project 263.287 FreshMon (High Resolution Freshwater Monitoring: FreshMon GMES Downstream Services) (www.freshmon.eu), which develops a new service line for the continuous provision of Earth Observation based products, integrated with in situ and hydrodynamic modelling components, for water quality monitoring.

  18. Direct determination of trace elements in boron nitride powders by slurry sampling total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Amberger, Martin A.; Hltig, Michael; Broekaert, Jos A. C.

    2010-02-01

    The use of slurry sampling total reflection X-ray fluorescence spectrometry (SlS-TXRF) for the direct determination of Ca, Cr, Cu, Fe, Mn and Ti in four boron nitride powders has been described. Measurements of the zeta potential showed that slurries with good stabilities can be obtained by the addition of polyethylenimine (PEI) at a concentration of 0.1 wt.% and by adjusting the pH at 4. For the optimization of the concentration of boron nitride in the slurries the net line intensities and the signal to background ratios were determined for the trace elements Ca and Ti as well as for the internal standard element Ga in the case of concentrations of boron nitride ranging from 1 to 30 mg mL -1. As a compromise with respect to high net line intensities and high signal to background ratios, concentrations of 5 mg mL -1 of boron nitride were found suitable and were used for all further measurements. The limits of detection of SlS-TXRF for the boron nitride powders were found to range from 0.062 to 1.6 ?g g - 1 for Cu and Ca, respectively. Herewith, they are higher than those obtained in solid sampling and slurry sampling graphite furnace atomic absorption spectrometry (SoS-GFAAS, SlS-GFAAS) as well as those of solid sampling electrothermal evaporation inductively coupled plasma optical emission spectrometry (SoS-ETV-ICP-OES). For Ca and Fe as well as for Cu and Fe, however, they were found to be lower than for GFAAS and for ICP-OES subsequent to wet chemical digestion, respectively. The universal applicability of SlS-TXRF to the analysis of samples with a wide variety of matrices could be demonstrated by the analysis of certified reference materials such as SiC, Al 2O 3, powdered bovine liver and borate ore with a single calibration. The correlation coefficients of the plots for the values found for Ca, Fe and Ti by SlS-TXRF in the boron nitride powders as well as in the before mentioned samples versus the reference values for the respective samples over a concentration range from 2.5 to 1470 ?g g - 1 were found to be 0.995, 0.991 and 0.997, respectively.

  19. Orientation of specifically 13C=O labeled phosphatidylcholine multilayers from polarized attenuated total reflection FT-IR spectroscopy.

    PubMed Central

    Hübner, W; Mantsch, H H

    1991-01-01

    Oriented multilayers of 1-myristoyl-2(1-13C)-myristoyl-sn-glycero-3-phosphatidylcholine (2[1-13C]DMPC) and 1-palmitoyl-2(1-13C)-palmitoyl-sn-glycero-3-phosphatidylcholine (2[1-13C]DPPC) were investigated by use of attenuated total reflection infrared spectroscopy with polarized light. Experiments were performed with the aim to determine the orientation of the two ester groups in these phospholipids in the solid state and in the hydrated state at temperatures below and above the respective gel to liquid-crystalline phase transitions. Substitution of the naturally occurring 12C carbonyl carbon atom by 13C in the ester group of the sn-2 chain of DMPC and DPPC shifts the infrared absorption of the carbonyl double bond stretching vibration to lower frequency. This results in two well-resolved ester C=O bands which can be assigned unequivocally to the sn-1 and sn-2 chains as they are separated by more than 40 cm-1. The two ester CO-O single bond stretching vibrations of the molecular fragments-CH2CO-OC-are also affected and the corresponding infrared absorption band shifts by 20 cm-1 on 13C-labeling of the carbonyl carbon atom. From the dichroic ratios of the individual ester bands in 2(1-13C)DMPC and 2(1-13C)DPPC we were able to demonstrate that the sn-1 and sn-2 ester C=O groups are similarly oriented with respect to the bilayer plane, with an angle greater than or equal to 60 degrees relative to the bilayer normal. The two CO-O single bonds on the other hand have very different orientations. The CH2CO-OC fragment of the sn-1 chain is oriented along the direction of the all-trans methylene chain, whereas the same molecular segment of the sn-2 carbon chain is directed toward the bilayer plane. This orientation of the ester groups is retained in the liquid-crystalline phase. The tilt angle of the hydrocarbon all-trans chains, relative to the membrane normal, is 25 degrees in the solid state of DMPC and DPPC multibilayers. In the hydrated gel state this angle varies between 26 degrees and 30 degrees, depending on temperature. Neither the orientation of the phosphate group, nor that of the choline group varies significantly in the different physical states of these phospholipids. PMID:1873463

  20. Comment on Sub-15 nm Hard X-Ray Focusing with a New Total-Reflection Zone Plate

    SciTech Connect

    Specht, Eliot D

    2011-01-01

    Takano et al. report the focusing of 10-keV X-rays to a size of 14.4 nm using a total-reflection zone plate (TRZP). This focal size is at the diffraction limit for the optic's aperture. This would be a noteworthy result, since the TRZP was fabricated using conventional lithography techniques. Alternative nanofocusing optics require more demanding fabrication methods. However, as I will discuss in this Comment, the intensity distribution presented by Takano et al. (Fig. 4 of ref. 1) is more consistent with the random speckle pattern produced by the scattering of a coherent incident beam by a distorted optic than with a diffraction-limited focus. When interpreted in this manner, the true focal spot size is {approx}70 nm: 5 times the diffraction limit. When a coherent photon beam illuminates an optic containing randomly distributed regions which introduce different phase shifts, the scattered diffraction pattern consists of a speckle pattern. Each speckle will be diffraction-limited: the peak width of a single speckle depends entirely on the source coherence and gives no information about the optic. The envelope of the speckle distribution corresponds to the focal spot which would be observed using incoherent illumination. The width of this envelope is due to the finite size of the coherently-diffracting domains produced by slope and position errors in the optic. The focal intensity distribution in Fig. 4 of ref. 1 indeed contains a diffraction-limited peak, but this peak contains only a fraction of the power in the focused, and forms part of a distribution of sharp peaks with an envelope {approx}70 nm in width, just as expected for a speckle pattern. At the 4mm focal distance, the 70 nm width corresponds to a slope error of 18 {micro}rad. To reach the 14 nm diffraction limit, the slope error must be reduced to 3 {micro}rad. Takano et al. have identified a likely source of this error: warping due to stress as a result of zone deposition. It will be interesting to see whether the use of a more rigid substrate gives improved results.

  1. ATR-FTIR spectroscopy detects alterations induced by organotin(IV) carboxylates in MCF-7 cells at sub-cytotoxic/-genotoxic concentrations

    PubMed Central

    Ahmad, Muhammad S; Mirza, Bushra; Hussain, Mukhtiar; Hanif, Muhammad; Ali, Saqib; Walsh, Michael J; Martin, Francis L

    2008-01-01

    The environmental impact of metal complexes such as organotin(IV) compounds is of increasing concern. Genotoxic effects of organotin(IV) compounds (0.01 ?g/ml, 0.1 ?g/ml or 1.0 ?g/ml) were measured using the alkaline single-cell gel electrophoresis (comet) assay to measure DNA single-strand breaks (SSBs) and the cytokinesis-block micronucleus (CBMN) assay to determine micronucleus formation. Biochemical-cell signatures were also ascertained using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. In the comet assay, organotin(IV) carboxylates induced significantly-elevated levels of DNA SSBs. Elevated micronucleus-forming activities were also observed. Following interrogation using ATR-FTIR spectroscopy, infrared spectra in the biomolecular range (900 cm-1 1800 cm-1) derived from organotin-treated MCF-7 cells exhibited clear alterations in their biochemical-cell fingerprint compared to control-cell populations following exposures as low as 0.0001 ?g/ml. Mono-, di- or tri-organotin(IV) carboxylates (0.1 ?g/ml, 1.0 ?g/ml or 10.0 ?g/ml) were markedly cytotoxic as determined by the clonogenic assay following treatment of MCF-7 cells with ? 1.0 ?g/ml. Our results demonstrate that ATR-FTIR spectroscopy can be applied to detect molecular alterations induced by organotin(IV) compounds at sub-cytotoxic and sub-genotoxic concentrations. This biophysical approach points to a novel means of assessing risk associated with environmental contaminants. PACS codes: 87.15.-v, 87.17.-d, 87.18.-h PMID:19351425

  2. ATM and ATR: Sensing DNA damage

    PubMed Central

    Yang, Jun; Xu, Zheng-Ping; Huang, Yun; Hamrick, Hope E.; Duerksen-Hughes, Penelope J.; Yu, Ying-Nian

    2004-01-01

    Cellular response to genotoxic stress is a very complex process, and it usually starts with the sensing or detection of the DNA damage, followed by a series of events that include signal transduction and activation of transcription factors. The activated transcription factors induce expressions of many genes which are involved in cellular functions such as DNA repair, cell cycle arrest, and cell death. There have been extensive studies from multiple disciplines exploring the mechanisms of cellular genotoxic responses, which have resulted in the identification of many cellular components involved in this process, including the mitogen-activated protein kinases (MAPKs) cascade. Although the initial activation of protein kinase cascade is not fully understood, human protein kinases ATM (ataxia-telangiectasia, mutated) and ATR (ATM and Rad3-related) are emerging as potential sensors of DNA damage. Current progresses in ATM/ATR research and related signaling pathways are discussed in this review, in an effort to facilitate a better understanding of genotoxic stress response. PMID:14716813

  3. Adsorption and oxidation of carbon monoxide on Pt/C, Pt3Co/C, and PtRu/C catalysts studied by in-situ attenuated total reflection Fourier-transform infrared.

    PubMed

    Sato, Takako; Kunimatsu, Keiji; Watanabe, Masahiro; Uchida, Hiroyuki

    2011-06-01

    The adsorption and oxidation of CO on commercial nanoparticle catalysts supported on carbon black (Pt/C, Pt3Co/C, PtRu/C) were examined at 23, 40, and 60 degrees C in 0.1 M HClO4 by use of in situ ATR-FTIR (attenuated total reflection Fourier-transform infrared) spectroscopy. Absorption bands for the adsorbed CO assigned to linear (atop) CO (CO(L)) and bridge CO (CO(B)) were observed around 2040 cm(-1) and 1850 cm(-1), respectively, at high CO coverage theta(CO) close to 0.8 on all three types of catalysts. The adsorption rates of both CO(L) and CO(B) at the initial stage were found to decrease in the order Pt/C > Pt3Co/C > PtRu/C, indicating that the interaction of CO with PtRu is weakest. The adsorption of CO on these catalysts resulted in the growth of a sharp O-H stretching band around 3630 to 3640 cm(-1), which was assigned to non-hydrogen-bonded water molecules (isolated H2O) co-adsorbed with CO. For the electrooxidation reaction of CO, PtRu/C exhibited the highest activity at all temperatures. It was confirmed that the dominant factor for determining CO oxidation activity was the onset potential for the oxidation of isolated H2O, E(onset)(H2O), to provide an oxygen species that is consumed in either a Langmuir-Hinshelwood mechanism (Pt/C, Pt3Co/C) or the bi-functional mechanism (PtRu/C). In addition, PtRu/C exhibited the weakest Pt-CO interaction. The values of E(onset)(H2O) at PtRu/C were lowest among the three catalysts from 23 to 60 degrees C. With increasing temperature, the E(onset)(H2O) at Pt/C and Pt3Co/C shifted to less positive potential, resulting in increased CO oxidation activity, while the shift in E(onset)(H2O) at PtRu/C was relatively small. PMID:21770153

  4. 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; Karl??a, 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 ? and ? forms. Molecules in ? and ? 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 ? and ? polymorphs were characterized and used throughout the method development and validation studies. Mixtures with different ratios of ? and ? forms were scanned using X-ray diffractometer with a scan rate of 0.250/min over an angular range of 19.5-21.0 2? and the peak heights for characteristic peak of ? form at 20.5 0.2 2? diffraction angle were used to generate a calibration curve. The detection limit of ? polymorph in ? form imatinib mesylate tablets was found as 4% and the linear regression analysis data for the calibration plots showed good linear relationship with correlation coefficient of 0.992 with respect to relative peak height in the concentration range of 12-75 wt% ? form containing tablet mixtures. The obtained results at each stage of the validation study proved that the method is specific, repeatable, precise and accurate, and could be used for determination of ? polymorph content in tablets produced by using ? polymorph of imatinib mesylate. The developed PXRD quantification method was used to monitor the polymorphic purity of ? form drug substance and corresponding drug products during the quality control analyses and stability studies, and the results indicated that ? form was stable and not converted to ? form during the manufacturing process and stability period. PMID:26099262

  5. ATR evaluation through the synthesis of multiple performance measures

    NASA Astrophysics Data System (ADS)

    Bassham, Christopher B.; Klimack, William K.; Bauer, Kenneth W., Jr.

    2002-07-01

    This research demonstrates the application of decision analysis (DA) techniques to decisions made within Automatic Target Recognition (ATR) technology development. This work is accomplished to improve the means by which ATR technologies are evaluated. The first step in this research was to create a flexible decision analysis framework that could be applied to several decisions across different ATR programs evaluated by the Comprehensive ATR Scientific Evaluation (COMPASE) Center of the Air Force Research Laboratory (AFRL). For the purposes of this research, a single COMPASE Center representative provided the value, utility, and preference functions for the DA framework. The DA framework employs performance measures collected during ATR classification system (CS) testing to calculate value and utility scores. The authors gathered data from the Moving and Stationary Target Acquisition and Recognition (MSTAR) program to demonstrate how the decision framework could be used to evaluate three different ATR CSs. A decision-maker may use the resultant scores to gain insight into any of the decisions that occur throughout the lifecycle of ATR technologies. Additionally, a means of evaluating ATR CS self-assessment ability is presented. This represents a new criterion that emerged from this study, and no present evaluation metric is known.

  6. ATR phosphorylates SMARCAL1 to prevent replication fork collapse

    PubMed Central

    Couch, Frank B.; Bansbach, Carol E.; Driscoll, Robert; Luzwick, Jessica W.; Glick, Gloria G.; Btous, Rmy; Carroll, Clinton M.; Jung, Sung Yun; Qin, Jun; Cimprich, Karlene A.; Cortez, David

    2013-01-01

    The DNA damage response kinase ataxia telangiectasia and Rad3-related (ATR) coordinates much of the cellular response to replication stress. The exact mechanisms by which ATR regulates DNA synthesis in conditions of replication stress are largely unknown, but this activity is critical for the viability and proliferation of cancer cells, making ATR a potential therapeutic target. Here we use selective ATR inhibitors to demonstrate that acute inhibition of ATR kinase activity yields rapid cell lethality, disrupts the timing of replication initiation, slows replication elongation, and induces fork collapse. We define the mechanism of this fork collapse, which includes SLX4-dependent cleavage yielding double-strand breaks and CtIP-dependent resection generating excess single-stranded template and nascent DNA strands. Our data suggest that the DNA substrates of these nucleases are generated at least in part by the SMARCAL1 DNA translocase. Properly regulated SMARCAL1 promotes stalled fork repair and restart; however, unregulated SMARCAL1 contributes to fork collapse when ATR is inactivated in both mammalian and Xenopus systems. ATR phosphorylates SMARCAL1 on S652, thereby limiting its fork regression activities and preventing aberrant fork processing. Thus, phosphorylation of SMARCAL1 is one mechanism by which ATR prevents fork collapse, promotes the completion of DNA replication, and maintains genome integrity. PMID:23873943

  7. Catalyzed oxidation of arsenic(III) by hydrogen peroxide on the surface of ferrihydrite: an in situ ATR FTIR study.

    PubMed

    Voegelin, Andreas; Hug, Stephan J

    2003-03-01

    Knowledge of arsenic redox kinetics is crucial for understanding the impact and fate of As in the environment and for optimizing As removal from drinking water. Rapid oxidation of As(III) adsorbed to ferrihydrite (FH) in the presence of hydrogen peroxide (H2O2) might be expected for two reasons. First, the adsorbed As(III) is assumed to be oxidized more readily than the undissociated species in solution. Second, catalyzed decomposition of H2O2 on the FH surface might also lead to As(III) oxidation. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy was used to monitor the oxidation of adsorbed As(III) on the FH surface in situ. No As(III) oxidation within minutes to hours was observed prior to H2O2 addition. Initial pseudo-first-order oxidation rate coefficients for adsorbed As(III), determined at H2O2 concentrations between 8.4 microM and 8.4 mM and pH values from 4 to 8, increased with the H2O2 concentration according to the equation log k(ox) (min(-1)) = 0.17 + 0.50 log [H2O] (mol/L), n = 21, r2 = 0.87. Only a weak pH dependence of log k(ox) was observed (approximately 0.04 logarithm unit increase per pH unit). ATR-FTIR experiments with As(III) adsorbed onto amorphous aluminum hydroxide showed that Fe was necessary to induce As(III) oxidation by catalytic H2O2 decomposition. Supplementary As(III) oxidation experiments in FH suspensions qualitatively confirmed the findings from the in situ ATR-FTIR experiments. Our results indicate that the catalyzed oxidation of As(III) by H2O2 on the surface of iron (hydr)oxides might be a relevant reaction pathway in environmental systems such as surface waters, as well as in engineered systems for As removal from water. PMID:12666928

  8. Characterization of attenuated total reflection infrared spectral intensity variations of immature and mature cotton fibers by two-dimensional correlation analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two-dimensional (2D) correlation analysis was applied to characterize the ATR spectral intensity fluctuations of immature and mature cotton fibers. Prior to 2D analysis, the spectra were leveled to zero at the peak intensity of 1800 cm-1 and then were normalized at the peak intensity of 660 cm-1 to ...

  9. Evaluation of metformin hydrochloride in Wistar rats by FTIR-ATR spectroscopy: A convenient tool in the clinical study of diabetes

    PubMed Central

    Ramalingam, P.; Reddy, Y. Padmanabha; Kumar, K. Vinod; Chandu, Babu Rao; Rajendran, K.

    2014-01-01

    Introduction: The IR absorption patterns (in cm?1) provide the basis to distinguish among the constituents and to separately quantify as well as qualify them and they possess many advantages such as very small sample volume requirement, good precision over entire physiological range, avoid of costly disposables, wealth of information from a single spectral measurement. The efficacy of anti-diabetic drug metformin hydrochloride as used to treat diabetic-induced Wistar rats and their sera were analyzed by FT-IR (ATR) in absorption mode. Materials and Methods: The present work was attempted in the study of normal and antidiabetic regimen-treated rat blood samples using FTIR spectroscopy by the attenuated total reflectance (ATR) sampling technique. The biomolecule characteristics were measured as intensity ratio parameter (IRP) values and interpreted. Results: To quantify the results three IRPs such as R1, R2 and R3 were calculated, respectively, for lipid, protein, and glucose. The glucose IRP value R3 showed, 0.3802, 0.3304, and 0.2847, respectively, for diseased, metformin-treated, and normal rats. Conclusion: The IRP values for glucose are compared to the glucose level obtained by using a glucometer. This study can be conveniently used in diagnostic procedures, patient compliance assessment, and efficacy evaluation of metformin hydrochlorides. PMID:25097400

  10. Film-forming process and biocide assessment of high-molecular-weight chitosan as determined by combined ATR-FTIR spectroscopy and antimicrobial assays.

    PubMed

    Fernandez-Saiz, P; Ocio, M J; Lagaron, J M

    2006-12-15

    This pioneering study reported about the film-forming properties of high-molecular-weight chitosan as followed in situ by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and has implications in fields such as biomedical, pharmaceutical, packaging, and coating applications. From the results, it was observed that immediately after dissolution in an acetic acid aqueous solution and subsequent casting over the ATR crystal, the formed carboxylate antimicrobial (-NH3+ -OOCH) species are not stable in the film formulation and become reduced over time; further assays confirmed previous research, which suggested that the presence and stability of these groups is strongly dependent, among other factors, on storage conditions. As-received chitosan and chitosan neutralized in NaOH films did not exhibit biocide performance towards Staphylococcus aureus. The antimicrobial tests were also found to strongly relate the presence of a sufficient quantity of these carboxylate groups to the chitosan activity as a biocide agent. Moreover, a novel methodology based on the use of a normalized infrared band centered at 1405 cm(-1) is proposed which can be correlated with the antimicrobial character of the biopolymer. PMID:16929529

  11. In situ ATR and DRIFTS studies of the nature of adsorbed CO? on tetraethylenepentamine films.

    PubMed

    Wilfong, Walter Christopher; Srikanth, Chakravartula S; Chuang, Steven S C

    2014-08-27

    CO2 adsorption/desorption onto/from tetraethylenepentamine (TEPA) films of 4, 10, and 20 ?m thicknesses were studied by in situ attenuated total reflectance (ATR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques under transient conditions. Molar absorption coefficients for adsorbed CO2 were used to determine the CO2 capture capacities and amine efficiencies (CO2/N) of the films in the DRIFTS system. Adsorption of CO2 onto surface and bulk NH2 groups of the 4 ?m film produced weakly adsorbed CO2, which can be desorbed at 50 C by reducing the CO2 partial pressure. These weakly adsorbed CO2 exhibit low ammonium ion intensities and could be in the form of ammonium-carbamate ion pairs and zwitterions. Increasing the film thickness enhanced the surface amine-amine interactions, resulting in strongly adsorbed ion pairs and zwitterions associated with NH and NH2 groups of neighboring amines. These adsorbed species may form an interconnected surface network, which slowed CO2 gas diffusion into and diminished access of the bulk amine groups (or amine efficiency) of the 20 ?m film by a minimum of 65%. Desorption of strongly adsorbed CO2 comprising the surface network could occur via dissociation of NH3(+)/NH2(+)NH2/NH ionic hydrogen bonds beginning from 60 to 80 C, followed by decomposition of NHCOO(-)/NCOO(-) at 100 C. These results suggest that faster CO2 diffusion and adsorption/desorption kinetics could be achieved by thinner layers of liquid or immobilized amines. PMID:25054585

  12. Acute Transfusion Reactions (ATRs) in Intensive Care Unit (ICU): A Retrospective Study

    PubMed Central

    Kumar, Rajesh; Gupta, Manvi; Gupta, Varun; Kaur, Amarjit; Gupta, Sonia

    2014-01-01

    Background: Blood transfusion is a frequent and integral part of critical care. Although life saving, it can occasionally be unsafe and result in a spectrum of adverse events. Acute transfusion reactions (ATRs) are probably under diagnosed in critically ill patients due to confusion of the symptoms with the underlying disease. Aim: To analyze the incidence and spectrum of ATRs occuring in critically ill patients. Materials and Methods: This was a retrospective review conducted from 1st April 2011 till 31st March 2013. The ATRs related to the administration of blood components in the patients admitted in various Intensive Care Units (ICUs) were recorded, analyzed and classified on the basis of their clinical features and laboratory tests. Results: During the study period 98651 blood components were issued. Out of these 21971 were issued to various ICUs. A total of 225 transfusion reactions were reported from the various critical care departments during this period. The most frequent were Febrile Non Hemolytic Transfusion Reactions (FNHTR) 136 (60.4%), allergic reactions 70 (31.2%), hemolytic reactions 1(0.4%) and non specific reactions 18 (8%). The incidence of ATRs in our study was found to be 1.09% in adult ICUs and 0.36% in pediatric ICUs. Conclusions: Blood transfusion is a vital therapeutic procedure with a potential risk to already critical patients. So a strict vigilance has to be kept and each transfusion has to be monitored carefully with prompt recognition and treatment of ATRs. A rational use of these products considering their deleterious effects can decrease transfusion related morbidity and mortality in the critically ill patients. PMID:24701502

  13. Molecular cloning of AtRS4, a seed specific multifunctional RFO synthase/galactosylhydrolase in Arabidopsis thaliana

    PubMed Central

    Gangl, Roman; Behmüller, Robert; Tenhaken, Raimund

    2015-01-01

    Stachyose is among the raffinose family oligosaccharides (RFOs) one of the major water-soluble carbohydrates next to sucrose in seeds of a number of plant species. Especially in leguminous seeds, e.g. chickpea, stachyose is reported as the major component. In contrast to their ambiguous potential as essential source of carbon for germination, RFOs are indigestible for humans and can contribute to diverse abdominal disorders. In the genome of Arabidopsis thaliana, six putative raffinose synthase genes are reported, whereas little is known about these putative raffinose synthases and their biochemical characteristics or their contribution to the RFO physiology in A. thaliana. In this paper, we report on the molecular cloning, functional expression in Escherichia coli and purification of recombinant AtRS4 from A. thaliana and the biochemical characterisation of the putative stachyose synthase (AtSTS, At4g01970) as a raffinose and high affinity stachyose synthase (Km for raffinose 259.2 ± 21.15 μM) as well as stachyose and galactinol specific galactosylhydrolase. A T-DNA insertional mutant in the AtRS4 gene was isolated. Only semi-quantitative PCR from WT siliques showed a specific transcriptional AtRS4 PCR product. Metabolite measurements in seeds of ΔAtRS4 mutant plants revealed a total loss of stachyose in ΔAtRS4 mutant seeds. We conclude that AtRS4 is the only stachyose synthase in the genome of A. thaliana that AtRS4 represents a key regulation mechanism in the RFO physiology of A. thaliana due to its multifunctional enzyme activity and that AtRS4 is possibly the second seed specific raffinose synthase beside AtRS5, which is responsible for Raf accumulation under abiotic stress. PMID:26483807

  14. Advanced correlation filter methods for SHARP ATR

    NASA Astrophysics Data System (ADS)

    Topiwala, Pankaj; Casasent, David; Nehemiah, Avinash

    2007-04-01

    A electro-optic (EO) and infrared (IR) automatic target recognition (ATR) system based on the minimum noise and correlation energy (MINACE) distortion invariant filter (DIF) is presented. The system uses exceptionally high resolution EO and IR data obtained from the Shared Reconnaissance Pod (SHARP). Excellent detection results are obtained. Furthermore, the selection of a key parameter - the MINACE filter parameter c - is fully automated using a training and validation set. We also present a set of correlation plane post processing methods to reduce false alarms and improve detection accuracies. The system is evaluated using multi-sensor imagery acquired using the SHARP sensor suite, the detection (P D) and false alarm (P FA) scores are presented for the problem of detecting aircrafts in the high resolution imagery. The scale and orientation of the targets are not assumed to be known, thus making the problem more realistic.

  15. ATR FTIR Mapping of Leather Fiber Panels

    NASA Astrophysics Data System (ADS)

    Tondi, G.; Grünewald, T.; Petutschnigg, A.; Schnabel, T.

    2015-01-01

    Leather fiber panels are very promising materials for many applications, not only for the easy availability of the constituents but also for their outstanding fi re-retardant properties. These innovative composite panels can be an excellent material for building insulation, and in recent times, the interest of industries in this composite board has considerably arisen. For this reason the discrimination of the components in the leather fiber panels is becoming fundamental in order to ensure their homogeneous properties. A method to characterize the surface of these materials is then required. An ATR FTIR mapping system for the leather fiber panels has been performed with a Perkin-Elmer microscope coupled with a Frontier FTIR spectrometer. The system has successfully allowed transforming the optical image to a chemical one. This technique can be considered as a right tool for routine controls of the surface quality, especially when the leather shavings cannot be optically distinguished.

  16. Association Mapping of Total Carotenoids in Diverse Soybean Genotypes Based on Leaf Extracts and High-Throughput Canopy Spectral Reflectance Measurements

    PubMed Central

    Dhanapal, Arun Prabhu; Ray, Jeffery D.; Singh, Shardendu K.; Hoyos-Villegas, Valerio; Smith, James R.; Purcell, Larry C.; King, C. Andy; Fritschi, Felix B.

    2015-01-01

    Carotenoids are organic pigments that are produced predominantly by photosynthetic organisms and provide antioxidant activity to a wide variety of plants, animals, bacteria, and fungi. The carotenoid biosynthetic pathway is highly conserved in plants and occurs mostly in chromoplasts and chloroplasts. Leaf carotenoids play important photoprotective roles and targeted selection for leaf carotenoids may offer avenues to improve abiotic stress tolerance. A collection of 332 soybean [Glycine max (L.) Merr.] genotypes was grown in two years and total leaf carotenoid content was determined using three different methods. The first method was based on extraction and spectrophotometric determination of carotenoid content (eCaro) in leaf tissue, whereas the other two methods were derived from high-throughput canopy spectral reflectance measurements using wavelet transformed reflectance spectra (tCaro) and a spectral reflectance index (iCaro). An association mapping approach was employed using 31,253 single nucleotide polymorphisms (SNPs) to identify SNPs associated with total carotenoid content using a mixed linear model based on data from two growing seasons. A total of 28 SNPs showed a significant association with total carotenoid content in at least one of the three approaches. These 28 SNPs likely tagged 14 putative loci for carotenoid content. Six putative loci were identified using eCaro, five loci with tCaro, and nine loci with iCaro. Three of these putative loci were detected by all three carotenoid determination methods. All but four putative loci were located near a known carotenoid-related gene. These results showed that carotenoid markers can be identified in soybean using extract-based as well as by high-throughput canopy spectral reflectance-based approaches, demonstrating the utility of field-based canopy spectral reflectance phenotypes for association mapping. PMID:26368323

  17. Investigation of the effect of atmospheric dust on the determination of total ozone from the earth's ultraviolet reflectivity measurements, 1

    NASA Technical Reports Server (NTRS)

    Dave, J. V.

    1976-01-01

    Two computer algorithms are described. These algorithms were used for computing the aximuth-independent component of the intensity of the monochromatic radiation emerging at the top of a pseudo-spherical atmosphere with arbitrary vertical distribution of ozone, and with any arbitrary height distribution of up to two different kinds of aerosol. This atmospheric model was assumed to rest on a surface obeying Lambert's law of reflection.

  18. Study on the Identification of Radix Bupleuri from Its Unofficial Varieties Based on Discrete Wavelet Transformation Feature Extraction of ATR-FTIR Spectroscopy Combined with Probability Neural Network.

    PubMed

    Jin, Wenying; Wan, Chayan; Cheng, Cungui

    2015-01-01

    The attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was employed to acquire the infrared spectra of Radix Bupleuri and its unofficial varieties: the root of Bupleurum smithii Wolff and the root of Bupleurum bicaule Helm. The infrared spectra and spectra of Fourier self-deconvolution (FSD), discrete wavelet transform (DWT), and probability neural network (PNN) of these species were analyzed. By the method of FSD, there were conspicuous differences of the infrared absorption peak intensity of different types between Radix Bupleuri and its unofficial varieties. But it is hard to tell the differences between the root of Bupleurum smithii Wolff and the root of Bupleurum bicaule. The differences could be shown more clearly when the DWT was used. The research result shows that by the DWT technology it is easier to identify Radix Bupleuri from its unofficial varieties the root of Bupleurum smithii Wolff and the root of Bupleurum bicaule. PMID:25784938

  19. Diffuse reflectance spectra of the palpebral conjunctiva and its utility as a noninvasive indicator of total hemoglobin

    NASA Astrophysics Data System (ADS)

    McMurdy, John W., III; Jay, Gregory D.; Suner, Selim; Trespalacios, Flor; Crawford, Gregory P.

    2006-01-01

    The palpebral conjunctiva is an attractive location to qualitatively examine for the presence of anemia; however, this method of diagnosis has not been shown to be accurate. A spectroscopic examination of the palpebral conjunctiva enables the use of a quantitative parameter as a basis for diagnoses. Visible range diffuse reflectance spectra from the palpebral conjunctiva are examined from 30 patients and hemoglobin levels are extracted from these signatures using both a partial least-squares (PLS) multivariate regression model and a discrete spectral region model. Hemoglobin concentration derived from both these models is compared to an in vitro measurement of hemoglobin. Root mean squared errors of cross validation for the two analytical methods are 0.67 g/dL and 1.07 g/dL, respectively. Conjunctival reflectance spectra coupled with a PLS analysis achieve an enhanced specificity and sensitivity for anemia diagnoses over reported observational studies using the palpebral conjunctiva and achieve improved accuracy to other reported methods of noninvasive hemoglobin measurement.

  20. Optimization of a glancing angle for simultaneous trace elemental analysis by using a portable total reflection X-ray fluorescence spectrometer

    NASA Astrophysics Data System (ADS)

    Kunimura, Shinsuke; Watanabe, Daisuke; Kawai, Jun

    2009-03-01

    By using a portable total reflection X-ray fluorescence spectrometer with a 1 W X-ray tube, a specimen containing nanograms of Ca, Sc, Ti, V, Cr, Mn, Fe, and Ni is measured at several glancing angles of incident X-rays. Continuum X-rays are used as the excitation source. The intensities of the spectral background which degrades sensitivity to trace elements are decreased with a decrease of the glancing angle, and all these elements are detected at the glancing angle of 0.13 smaller than the critical angle for total reflection of the incident X-rays (0.20). An optimum glancing angle for simultaneously detecting these trace elements is around 0.13, and detection limits at 0.13 are sub-nanograms to ten nanograms.

  1. Total-reflection inelastic X-ray scattering from a 10-nm thick La0.6Sr0.4CoO3 thin film.

    PubMed

    Fister, T T; Fong, D D; Eastman, J A; Iddir, H; Zapol, P; Fuoss, P H; Balasubramanian, M; Gordon, R A; Balasubramaniam, K R; Salvador, P A

    2011-01-21

    To study equilibrium changes in composition, valence, and electronic structure near the surface and into the bulk, we demonstrate the use of a new approach, total-reflection inelastic x-ray scattering, as a sub-keV spectroscopy capable of depth profiling chemical changes in thin films with nanometer resolution. By comparing data acquired under total x-ray reflection and penetrating conditions, we are able to separate the O K-edge spectra from a 10 nm La0.6Sr0.4CoO3 thin film from that of the underlying SrTiO3 substrate. With a smaller wavelength probe than comparable soft x-ray absorption measurements, we also describe the ability to easily access dipole-forbidden final states, using the dramatic evolution of the La N4,5 edge with momentum transfer as an example. PMID:21405295

  2. Simple method of determination of copper, mercury and lead in potable water with preliminary pre-concentration by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Ho?y?ska, B.; Ostachowicz, B.; W?grzynek, D.

    1996-06-01

    Total reflection X-ray fluorescence spectrometry and chemical pre-concentration procedures have been applied for the analysis of trace concentrations of copper, mercury, and lead in drinking water samples. A simple total reflection module has been used in X-ray measurements. The elements under investigation were pre-concentrated by complexation using a mixture of carbamates followed by solvent extraction with methyl isobutyl ketone. The preconcentration procedure was tested with the use of twice-distilled water samples and samples of mineral and tap water spiked with known additions of copper, mercury, and lead. The obtained recovery and precision values are presented. The minimum detection limits for the determination of these elements in mineral and tap water samples were found to be 40 ng l -1, 60 ng l -1, and 60 ng l -1, respectively.

  3. [Osteosarcoma and ATR-16 syndrome: association or coincidence?].

    PubMed

    Regueiro Garca, A; Saborido Fiao, R; Gonzlez Calvete, L; Vzquez Donsin, M; Couselo Snchez, J M; Fernndez Sanmartn, M

    2015-01-01

    ATR-16 syndrome is due to alterations on chromosome 16p13.3, and is usually accompanied by alpha-thalassemia, mild-moderate mental retardation, dysmorphic facial features, skeletal and genitourinary malformations. There are no references of the combination of ATR-16 syndrome and osteosarcoma in the literature. Osteosarcoma usually has a complex karyotype, characterized by a high degree of heterogeneity of chromosomal aberrations, among which is the involvement of chromosome 16. We report a case of a patient with ATR-16 syndrome diagnosed with femoral osteosarcoma. PMID:24631100

  4. Achieving safety/risk goals for less ATR backup power upgrades

    SciTech Connect

    Atkinson, S.A.

    1995-10-01

    The Advanced Test Reactor probabilistic risk assessment for internal fire and flood events defined a relatively high risk for a total loss of electric power possibly leading to core damage. Backup power sources were disabled due to fire and flooding in the diesel generator area with propagation of the flooding to a common switchgear room. The ATR risk assessment was employed to define options for relocation of backup power system components to achieve needed risk reduction while minimizing costs. The risk evaluations were performed using sensitivity studies and importance measures. The risk-based evaluations of relocation options for backup power systems saved over $3 million from what might have been otherwise considered {open_quotes}necessary{close_quotes} for safety/risk improvement. The ATR experience shows that the advantages of a good risk assessment are to define risk significance, risk specifics, and risk solutions which enable risk goals to be achieved at the lowest cost.

  5. Evidence of acid-base interactions between amines and model indoor surfaces by ATR-FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Destaillats, Hugo; Singer, Brett C.; Gundel, Lara A.

    Molecular associations of pyridine with cellulose and gypsum, surrogates for common indoor surface materials, were studied using an attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectrophotometric method. The purpose of this study was to gain insight into the molecular interactions of amines with well-characterized materials that affect their partitioning between indoor air and surfaces. The experimental results suggest the presence of at least two sorptive states for volatile and semivolatile amines, attributed to the chemisorbed species and to a more labile surface state (i.e., physisorbed pyridine). Both exhibited spectroscopic signatures corresponding to aromatic C-H stretching modes (2950-3100 cm -1) in the studied spectral region. Chemisorbed pyridine could be identified by the presence of additional IR signals in the N-H and O-H stretching region of the spectrum (2900-3600 cm -1). During desorption under a stream of N 2, surface enrichment in the chemisorbed species was evidenced by a slower reduction of the absorbance of the broad band at 2900-3600 cm -1 in relation to the total pyridine absorbance change. This spectroscopic evidence for acid-base interactions between amines and surfaces is consistent with the desorption behavior observed in previous work for nicotine from model surfaces.

  6. Investigation of the effect of atmospheric dust on the determination of total ozone from the earth's ultraviolet reflectivity measurements

    NASA Technical Reports Server (NTRS)

    Dave, J. V.

    1977-01-01

    Results are presented on the effect of atmospheric aerosols on the value of total ozone, in an atmospheric column of the terrestrial atmosphere, estimated from the simulated measurements of the ultraviolet radiation back scattered by the earth atmosphere models. Simulated measurements were used in five (configuration of the BUV experiment of Nimbus-4 satellite), and in six (configuration of the TOMS section of the SBUV/TOMS experiment on Nimbus-G) narrow spectral regions in the ultraviolet part of the spectrum.

  7. [Research on Rapid Discrimination of Edible Oil by ATR Infrared Spectroscopy].

    PubMed

    Ma, Xiao; Yuan, Hong-fu; Song, Chun-feng; Hu, Ai-qin; Li, Xiao-yu; Zhao, Zhong; Li, Xiu-qin; Guo Zhen; Zhu, Zhi-qiang

    2015-07-01

    A rapid discrimination method of edible oils, KL-BP model, was proposed by attenuated total reflectance infrared spectroscopy. The model extracts the characteristic of classification from source data by KL and reduces data dimension at the same time. Then the neural network model is constructed by the new data which as the input of the model. 84 edible oil samples which include sesame oil, corn oil, canola oil, blend oil, sunflower oil, peanut oil, olive oil, soybean oil and tea seed oil, were collected and their infrared spectra determined using an ATR FT-IR spectrometer. In order to compare the method performance, principal component analysis (PCA) direct-classification model, KL direct-classification model, PLS-DA model, PCA-BP model and KL-BP model are constructed in this paper. The results show that the recognition rates of PCA, PCA-BP, KL, PLS-DA and KL-BP are 59.1%, 68.2%, 77.3%, 77.3% and 90.9% for discriminating the 9 kinds of edible oils, respectively. KL extracts the eigenvector which make the distance between different class and distance of every class ratio is the largest. So the method can get much more classify information than PCA. BP neural network can effectively enhance the classification ability and accuracy. Taking full of the advantages of KL in extracting more category information in dimension reducing and the features of BP neural network in self-learning, adaptive, nonlinear, the KL-BP method has the best classification ability and recognition accuracy and great importance for rapidly recognizing edible oil in practice. PMID:26717744

  8. ATR National Scientific User Facility 2009 Annual Report

    SciTech Connect

    Todd R. Allen; Mitchell K. Meyer; Frances Marshall; Mary Catherine Thelen; Jeff Benson

    2010-11-01

    This report describes activities of the ATR NSUF from FY-2008 through FY-2009 and includes information on partner facilities, calls for proposals, users week and education programs. The report also contains project information on university research projects that were awarded by ATR NSUF in the fiscal years 2008 & 2009. This research is university-proposed researcher under a user facility agreement. All intellectual property from these experiments belongs to the university per the user agreement.

  9. Redefining automatic target recognition (ATR) performance standards

    NASA Astrophysics Data System (ADS)

    Waagen, Donald; Hester, Charles; Schmid, Ben; Phillips, Margaret; Thompson, M. Shane; Vanstone, Steven; Risko, Kelly

    2011-06-01

    Present descriptors for Automatic Target Recognition (ATR) performance are inadequate for use in comparing algorithms that are purported to be a solution to the problem. The use of receiver operator characteristic curves (ROCs) is a defacto standard, but they do not communicate several key performance measures, including (i) intrinsic separation between classes in the input space, (ii) the efficacy of the mapping induced by the algorithm, (iii) the complexity of the algorithmic mapping, and (iv) a measure of the generalization of the proposed solution. Previous work by Sims et. al.2,5 has addressed the distortion of the evaluation sets to indicate an algorithm's capability (or lack thereof) for generalization and handling of unspecified cases. This paper addresses the rethinking of the summary statistics used for understanding the performance of a solution. We propose new approaches for solution characterization, allowing algorithm performance comparison in an equitable and insightful manner. This paper proffers some examples and suggests directions for new work from the community in this field.

  10. Ladar ATR via probabilistic open set techniques

    NASA Astrophysics Data System (ADS)

    Scherreik, Matthew; Rigling, Brian

    2014-06-01

    Target recognition algorithms trained using finite sets of target and confuser data result in classifiers limited by the training set. Algorithms trained under closed set assumptions do not account for the infinite universe of confusers found in practice. In contrast, classification algorithms developed under open set assumptions label inputs not present in the training data as unknown instead of assigning the most likely class. We present an approach to open set recognition that utilizes class posterior estimates to determine probability thresholds for classification. This is accomplished by first training a support vector machine (SVM) in a 1-vs-all configuration on a training dataset containing only target classes. A validation set containing only class data belonging to the training set is used to iteratively determine appropriate posterior probability thresholds for each target class. The testing dataset, which contains targets present in the training data as well as several confuser classes, is first classified by the 1-vs-all SVM. If the estimated posterior for an input falls below the threshold, the target is labeled as unknown. Otherwise, it is labeled with the class resulting from the SVM decision. We apply our method to automatic target recognition (ATR) of ladar range images and compare its performance to current open set and closed set recognition techniques.

  11. LWRS ATR Irradiation Testing Readiness Status

    SciTech Connect

    Kristine Barrett

    2012-09-01

    The Light Water Reactor Sustainability (LWRS) Program was established by the U.S. Department of Energy Office of Nuclear Energy (DOE-NE) to develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the life of the current reactors. The LWRS Program is divided into four R&D Pathways: (1) Materials Aging and Degradation; (2) Advanced Light Water Reactor Nuclear Fuels; (3) Advanced Instrumentation, Information and Control Systems; and (4) Risk-Informed Safety Margin Characterization. This report describes an irradiation testing readiness analysis in preparation of LWRS experiments for irradiation testing at the Idaho National Laboratory (INL) Advanced Test Reactor (ATR) under Pathway (2). The focus of the Advanced LWR Nuclear Fuels Pathway is to improve the scientific knowledge basis for understanding and predicting fundamental performance of advanced nuclear fuel and cladding in nuclear power plants during both nominal and off-nominal conditions. This information will be applied in the design and development of high-performance, high burn-up fuels with improved safety, cladding integrity, and improved nuclear fuel cycle economics

  12. Estimation of direct, diffuse, and total FPARs from Landsat surface reflectance data and ground-based estimates over six FLUXNET sites

    NASA Astrophysics Data System (ADS)

    Li, Wenjuan; Fang, Hongliang

    2015-04-01

    The fraction of photosynthetically active radiation (PAR) absorbed by green elements (FPAR) is an essential climate variable (ECV) in quantifying canopy absorbed PAR (APAR) and gross and net primary production. It has been demonstrated that FPAR is larger under totally diffuse than clear sky conditions because all canopy parts can absorb lights effectively under diffuse conditions. The direct and diffuse FPARs are defined, therefore, as the FPAR values obtained under clear (most sunny) and overcast (most cloudy) conditions, respectively, and FPAR represents the summed canopy absorption efficiency for both direct and diffuse PAR. Satellite FPAR products, such as MODIS, GEOV1, MERIS, and JRC-TIP, have been generated at different temporal and spatial resolutions. Except for JRC-TIP which generates direct and diffuse FPARs separately, all the other products typically correspond to the instantaneous black-sky FPAR under direct illumination only. However, even under fully clear sky conditions, the proportion of diffuse PAR over the surface cannot be ignored. Otherwise, FPAR will be underestimated, especially for small leaf area index (LAI) region. To address this, the present study developed a new approach to estimate direct, diffuse, and total FPARs, separately, from Landsat 30m surface reflectance data. Field-measured direct and diffuse FPARs were first derived for crops, deciduous broadleaf forests, and evergreen needleleaf forests at six FLUXNET sites. Then, a coupled soil-leaf-canopy (SLC) radiative transfer model was used to simulate surface reflectance under direct and diffuse illumination conditions, respectively. Direct, diffuse, and total FPARs were estimated by comparing Landsat-5 Thematic Mapper (TM) data and simulated surface reflectances using a lookup table approach. The differences between the Landsat-estimated and the field-measured FPARs are less than 0.05 (10%). The diffuse FPAR is higher than the direct FPAR by up to 19.38%, whereas the total FPAR is larger than the direct FPAR by up to 16.07%. The direct APAR is higher than the diffuse APAR under clear-sky conditions, but underestimates the total APAR by -277.72 ?mol s-1 m-2 on average. We recommend that the total FPAR should be generated from current satellite sensors, and the differences in FPAR definitions should be considered in the estimation of APAR in vegetation models. More frequent field measurements are necessary to improve the accuracy of ground FPAR measurements and to validate instantaneous satellite products. The approach described here can be extended to estimate direct, diffuse, and total FPARs from other satellite data, and the obtained FPAR variables could be helpful to improve modeling of vegetation processes.

  13. Liquid phase microextraction strategies combined with total reflection X-ray spectrometry for the determination of low amounts of inorganic antimony species in waters.

    PubMed

    Margu, Eva; Sagu, Marta; Queralt, Ignasi; Hidalgo, Manuela

    2013-07-01

    In the present study, and taking into account the microanalytical capability of total reflection X-ray spectrometry (TXRF), we explored the possibilities of hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME) combined with TXRF for the determination of low amounts of inorganic Sb species in waters. For each of the LPME configurations aforementioned, experimental parameters affecting Sb extraction but specially the proper sample preparation process (deposition volume on the reflective carrier and drying mode) and measurement conditions for subsequent TXRF analysis have been carefully evaluated. The best analytical strategy for the determination of Sb(III) and Sb(V) in the low ?g L(-1) range was found to be the application of the DLLME mode before TXRF analysis. The developed methodology was successfully applied to the determination of inorganic Sb speciation in different types of spiked water samples. PMID:23790285

  14. Numerical simulation by TVD schemes of complex shock reflections from airfoils at high angle of attack. [Total Variation Diminishing

    NASA Technical Reports Server (NTRS)

    Moon, Young J.; Yee, H. C.

    1987-01-01

    The shock-capturing capability of total variation diminishing (TVD) schemes is demonstrated for a more realistic complex shock-diffraction problem for which the experimental data are available. Second-order explicit upwind and symmetric TVD schemes are used to solve the time-dependent Euler equations of gas dynamics for the interaction of a blast wave with an airfoil at high angle-of-attack. The test cases considered are a time-dependent moving curved-shock wave and a contant moving planar-shock wave impinging at an angle-of-attack 30 deg on a NACA 0018 airfoil. Good agreement is obtained between isopycnic contours computed by the TVD schemes and those from experimental interferograms. No drastic difference in flow-field structure is found between the curved- and planar-shock wave cases, except for a difference in density level near the lower surface of the airfoil. Computation for cases with higher shock Mach numbers is also possible. Numerical experiments show that the symmetric TVD scheme is less sensitive to the boundary conditions treatment than the upwind scheme.

  15. Study on the refractive index matching effect of ultrasound on optical clearing of bio-tissues based on the derivative total reflection method

    PubMed Central

    Zeng, Huanhuan; Wang, Jin; Ye, Qing; Deng, Zhichao; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2014-01-01

    In recent years, the tissue optical clearing (OC) technique in the biomedicine field has drawn lots of attention. Various physical and chemical methods have been introduced to improve the efficacy of OC. In this study, the effect of the combination of glycerol and ultrasound treatment on OC of in vitro porcine muscle tissues has been investigated. The refractive index (RI) matching mechanism of OC was directly observed based on the derivative total reflection method. A theoretical model was used to simulate the proportion of tissue fluid in the illuminated area. Moreover, the total transmittance spectra have been obtained by a spectrometer over the range from 450 nm to 700 nm. The administration of glycerol and ultrasound has led to an increase of the RI of background medium and a more RI matching environment was achieved. The experimental results support the validity of the ultrasound treatment for OC. The RI matching mechanism has been firstly quantitatively analyzed based on the derivative total reflection method. PMID:25360366

  16. Application of the total reflection X-ray fluorescence method to the elemental analysis of brain tumors of different types and grades of malignancy

    NASA Astrophysics Data System (ADS)

    Lankosz, M. W.; Grzelak, M.; Ostachowicz, B.; Wandzilak, A.; Szczerbowska-Boruchowska, M.; Wrobel, P.; Radwanska, E.; Adamek, D.

    2014-11-01

    The process of carcinogenesis may influence normal biochemical reactions leading to alterations in the elemental composition of the tissue. Total reflection X-ray fluorescence analysis (TXRF) was applied to the elemental analysis of different brain tumors. The following elements were present in all the neoplastic tissues analyzed: K, Ca, Fe, Cu, Zn and Rb. The results of the analysis showed that the elemental composition of a relatively small fragment of tissue represents satisfactorily the biochemical signature of a cancer. On the basis of the element concentrations determined, it was possible to differentiate between some types of brain tumors.

  17. Direct real-time observation of actin filament branching mediated by Arp2/3 complex using total internal reflection fluorescence microscopy

    PubMed Central

    Amann, Kurt J.; Pollard, Thomas D.

    2001-01-01

    Existing methods for studying actin filament dynamics have allowed analysis only of bulk samples or individual filaments after treatment with the drug phalloidin, which perturbs filament dynamics. Total internal reflection fluorescence microscopy with rhodamine-labeled actin allowed us to observe polymerization in real time, without phalloidin. Direct measurements of filament growth confirmed the rate constants measured by electron microscopy and established that rhodamine actin is a kinetically inactive tracer for imaging. In the presence of activated Arp2/3 complex, growing actin filaments form branches at random sites along their sides, rather than preferentially from their barbed ends. PMID:11742068

  18. Validation of ATR Fission Power Deposition Fraction in HEU and LEU Fuel Plates

    SciTech Connect

    G. S. Chang

    2008-09-01

    The Advanced Test Reactor (ATR) is a high power (250 MW), high neutron flux research reactor operating in the United States. Powered with highly enriched uranium (HEU), the ATR has a maximum unperturbed thermal neutron flux rating of 1.0 x 1015 n/cm2s. Because of its high power and large test volumes located in high flux areas, the ATR is an ideal candidate for assessing the feasibility of converting an HEU driven reactor to a low-enriched core. A detailed plate-by-plate MCNP ATR full core model has been developed and validated for the low-enriched uranium (LEU) fuel conversion feasibility study. Using this model, an analysis has been performed to determine the LEU density and U-235 enrichment required in the fuel meat to yield equivalent K-eff versus effective full power days (EFPDs) between the HEU and LEU cores. This model has also been used to optimize U-235 content of the LEU core, minimizing the differences in K-eff and heat flux profile between the HEU and LEU cores at 115 MW total core power for 125 EFPDs. The LEU core conversion feasibility study evaluated foil type (U-10Mo) fuel with the LEU reference design of 19.7 wt% U-235 enrichment. The LEU reference design has a fixed fuel meat thickness of 0.330 mm and can sustain the same operating cycle length as the HEU fuel. Heat flux and fission power density are parameters that are proportional to the fraction of fission power deposited in fuel. Thus, the accurate determination of the fraction of fission power deposited in the fuel is important to ATR nuclear safety. In this work, a new approach was developed and validated, the Tally Fuel Cells Only (TFCO) method. This method calculates and compares the fission power deposition fraction between HEU and LEU fuel plates. Due to the high density of the U-10Mo LEU fuel, the fission ?-energy deposition fraction is 37.12%, which is larger than the HEUs ?-energy deposition fraction of 19.7%. As a result, the fuel decay heat cooling will need to be improved. During the power operation, the total fission energy (200 MeV per fission) deposition fraction of LEU and HEU are 90.9% and 89.1%, respectively.

  19. Structural changes in cytochrome c oxidase induced by binding of sodium and calcium ions: an ATR-FTIR study.

    PubMed

    Marchal, Amandine; Iwaki, Masayo; Rich, Peter R

    2013-04-17

    Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to investigate the binding of Na(+) and Ca(2+)cations to bovine cytochrome c oxidase in its fully oxidized and partially reduced, cyanide-ligated (a(2+)a3(3+)-CN) (mixed valence) forms. These ions induced distinctly different IR binding spectra, indicating that the induced structural changes are different. Despite this, their binding spectra were mutually exclusive, confirming their known competitive binding behavior. Dissociation constants for Na(+) and Ca(2+) with the oxidized enzyme were 1.2 mM and 11 ?M, respectively and Na(+) binding appeared to involve cooperative binding of two Na(+). Ca(2+) binding induced a large IR spectrum, with prominent amide I/II polypeptide changes, bandshifts assigned to carboxylate and an arginine, and a number of bandshifts of heme a. The Na(+)-induced binding spectrum showed much weaker amide I/II and heme a changes but had similar shifts assignable to carboxylate and arginine residues. Yeast CcO also displayed a calcium-induced IR and UV/visible binding spectra, though of lower intensities. This was attributed to the difficulty in fully depleting Ca(2+) from its binding site, as has been found with bacterial CcOs. The implications of Ca(2+)/Na(+) ion binding are discussed in terms of structure and possible modulation of core catalytic function. PMID:23537388

  20. In situ particle film ATR FTIR spectroscopy of poly (N-isopropyl acrylamide) (PNIPAM) adsorption onto talc.

    PubMed

    Beattie, David A; Addai-Mensah, Jonas; Beaussart, Audrey; Franks, George V; Yeap, Kai-Ying

    2014-12-01

    The adsorption of poly(N-isopropyl acrylamide) (PNIPAM) onto talc from aqueous solutions has been studied using the in situ methodology of particle film attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. PNIPAM was observed to adsorb significantly onto the talc particle film at a temperature below its lower critical solution temperature (LCST). Peak shifts were seen in the adsorbed layer FTIR spectrum that match those observed when PNIPAM solution is heated above its LCST. This observation indicates that adsorption causes a conformational re-arrangement similar to that seen when PNIPAM undergoes a coil-to-globule transition, in this case presumably induced by hydrophobic interactions between PNIPAM and the talc basal plane surface. The kinetics of adsorption are seen to be complex, with potential influences of conformational rearrangement and differential adsorption kinetics for the two dominant surface regions of talc particles. The adsorbed PNIPAM was seen to be exceptionally resistant to removal, with no desorption occurring when a background electrolyte solution was flowed over the adsorbed layer. Spectra acquired of the adsorbed polymer layer heated above the LCST reveal that a further conformational rearrangement takes place for the adsorbed layer, finalizing the transition from coil-to-globule that was initiated by the interaction with the mineral surface. PMID:25330994

  1. 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. PMID:23451370

  2. FLUX SENSOR EVALUATIONS AT THE ATR CRITICAL FACILITY

    SciTech Connect

    Troy Unruh; Joy Rempe; David Nigg; George Imel; Jason Harris; Eric Bonebrake

    2010-11-01

    The Advanced Test Reactor (ATR) and the ATR Critical (ATRC) facilities lack real-time methods for detecting thermal neutron flux and fission reaction rates for irradiation capsules. Direct measurements of the actual power deposited into a test are now possible without resorting to complicated correction factors. In addition, it is possible to directly measure minor actinide fission reaction rates and to provide time-dependent monitoring of the fission reaction rate or fast/thermal flux during transient testing. A joint Idaho State University /Idaho National Laboratory ATR National Scientific User Facility (ATR NSUF) project was recently initiated to evaluate new real-time state-of-the-art in-pile flux detection sensors. Initially, the project is comparing the accuracy, response time, and long duration performance of French Atomic Energy Commission (CEA)-developed miniature fission chambers, specialized self-powered neutron detectors (SPNDs) by the Argentinean National Energy Commission (CNEA), specially developed commercial SPNDs, and back-to-back fission (BTB) chambers developed by Argonne National Laboratory (ANL). As discussed in this paper, specialized fixturing and software was developed by INL to facilitate these joint ISU/INL evaluations. Calculations were performed by ISU to assess the performance of and reduce uncertainties in flux detection sensors and compare data obtained from these sensors with existing integral methods employed at the ATRC. Ultimately, project results will be used to select the detector that can provide the best online regional ATRC power measurement. It is anticipated that project results may offer the potential to increase the ATRC’s current power limit and its ability to perform low-level irradiation experiments. In addition, results from this effort will provide insights about the viability of using these detectors in the ATR. Hence, this effort complements current activities to improve ATR software tools, computational protocols and in-core instrumentation under the ATR Modeling, Simulation and V&V Upgrade initiative, as well as the work to replace nuclear instrumentation under the ATR Life Extension Project (LEP) and provide support to the ATR NSUF.

  3. Airborne particulate matter (PM) filter analysis and modeling by total reflection X-ray fluorescence (TXRF) and X-ray standing wave (XSW).

    PubMed

    Borgese, L; Salmistraro, M; Gianoncelli, A; Zacco, A; Lucchini, R; Zimmerman, N; Pisani, L; Siviero, G; Depero, L E; Bontempi, E

    2012-01-30

    This work is presented as an improvement of a recently introduced method for airborne particulate matter (PM) filter analysis [1]. X-ray standing wave (XSW) and total reflection X-ray fluorescence (TXRF) were performed with a new dedicated laboratory instrumentation. The main advantage of performing both XSW and TXRF, is the possibility to distinguish the nature of the sample: if it is a small droplet dry residue, a thin film like or a bulk sample. Another advantage is related to the possibility to select the angle of total reflection to make TXRF measurements. Finally, the possibility to switch the X-ray source allows to measure with more accuracy lighter and heavier elements (with a change in X-ray anode, for example from Mo to Cu). The aim of the present study is to lay the theoretical foundation of the new proposed method for airborne PM filters quantitative analysis improving the accuracy and efficiency of quantification by means of an external standard. The theoretical model presented and discussed demonstrated that airborne PM filters can be considered as thin layers. A set of reference samples is prepared in laboratory and used to obtain a calibration curve. Our results demonstrate that the proposed method for quantitative analysis of air PM filters is affordable and reliable without the necessity to digest filters to obtain quantitative chemical analysis, and that the use of XSW improve the accuracy of TXRF analysis. PMID:22284465

  4. Airborne Particulate Matter (PM) filter analysis and modeling by Total reflection X-Ray Fluorescence (TXRF) and X-Ray Standing Wave (XSW)

    PubMed Central

    Borgese, L.; Salmistraro, M.; Gianoncelli, A; Zacco, A.; Lucchini, R.; Zimmerman, N.; Pisani, L.; Siviero, G.; Depero, L. E.; Bontempi, E.

    2011-01-01

    This work is presented as an improvement of a recently introduced method for airborne particulate matter (PM) filter analysis [1]. X-ray Standing Wave (XSW) and Total reflection X-Ray Fluorescence (TXRF) were performed with a new dedicated laboratory instrumentation. The main advantage of performing both XSW and TXRF, is the possibility to distinguish the nature of the sample: if it is a small droplet dry residue, a thin film like or a bulk sample; and to select the angle of total reflection to make TXRF measurements. Finally, the possibility to switch the X-ray source allows to measure with more accuracy lighter and heavier elements (with a a change in X-ray anode, for example from Mo to Cu). The aim of the present study is to lay the theoretical foundation of the new proposed method for airborne PM filters quantitative analysis improving the accuracy and efficiency of quantification by means of an external standard. The theoretical model presented and discussed demonstrated that airborne PM filters can be considered as thin layers. A set of reference samples is prepared in laboratory and used to obtain a calibration curve. Our results demonstrate that the proposed method for quantitative analysis of air PM filters is affordable and reliable without the necessity to digest filters to obtain quantitative chemical analysis, and that the use of XRW improve the accuracy of TXRF analysis. PMID:22284465

  5. Conformational changes and orientation of Humicola lanuginosa lipase on a solid hydrophobic surface: an in situ interface Fourier transform infrared-attenuated total reflection study.

    PubMed Central

    Noinville, Sylvie; Revault, Madeleine; Baron, Marie-Hlne; Tiss, Ali; Yapoudjian, Stphane; Ivanova, Margarita; Verger, Robert

    2002-01-01

    This study was done to better understand how lipases are activated at an interface. We investigated the conformational and solvation changes occurring during the adsorption of Humicola lanuginosa lipase (HLL) onto a hydrophobic surface using Fourier transform infrared-attenuated total reflection spectroscopy. The hydrophobic surfaces were obtained by coating silicon attenuated total reflection crystal with octadecyltrichlorosilane. Analysis of vibrational spectra was used to compare the conformation of HLL adsorbed at the aqueous-solid interface with its conformation in solution. X-ray crystallography has shown that HLL exists in two conformations, the closed and open forms. The conformational changes in HLL caused by adsorption onto the surface were compared with those occurring in three reference proteins, bovine serum albumin, lysozyme, and alpha-chymotrypsin. Adsorbed protein layers were prepared using proteins solutions of 0.005 to 0.5 mg/mL. The adsorptions of bovine serum albumin, lysozyme, and alpha-chymotrypsin to the hydrophobic support were accompanied by large unfoldings of ordered structures. In contrast, HLL underwent no secondary structure changes at first stage of adsorption, but there was a slight folding of beta-structures as the lipase monolayer became complete. Solvation studies using deuterated buffer showed an unusual hydrogen/deuterium exchange of the peptide CONH groups of the adsorbed HLL molecules. This exchange is consistent with the lipase being in the native open conformation at the water/hydrophobic interface. PMID:11964257

  6. Homeostatic regulation of meiotic DSB formation by ATM/ATR

    SciTech Connect

    Cooper, Tim J.; Wardell, Kayleigh; Garcia, Valerie; Neale, Matthew J.

    2014-11-15

    Ataxia–telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction of numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed.

  7. ATR NATIONAL SCIENTIFIC USER FACILITY INSTRUMENTATION ENHANCEMENT EFFORTS

    SciTech Connect

    Joy L. Rempe; Mitchell K. Meyer

    2009-04-01

    A key component of the Advanced Test Reactor (ATR) National Scientific User Facility (NSUF) effort is to enhance instrumentation techniques available to users conducting irradiation tests in this unique facility. In particular, development of sensors capable of providing ‘real-time’ measurements of key irradiation parameters is emphasized because of their potential to offer increased fidelity data and reduced post-test examination costs. This paper describes the strategy for identifying new instrumentation needed for ATR irradiations and the program underway to develop and evaluate new sensors to address these needs. Accomplishments from this program are illustrated by describing several new sensors now available to users of the ATR NSUF. In addition, progress is reported on current research efforts to provide users improved in-pile instrumentation.

  8. ATR PDQ and MCWO Fuel Burnup Analysis Codes Evaluation

    SciTech Connect

    G.S. Chang; P. A. Roth; M. A. Lillo

    2009-11-01

    The Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL) is being studied to determine the feasibility of converting it from the highly enriched Uranium (HEU) fuel that is currently uses to low enriched Uranium (LEU) fuel. In order to achieve this goal, it would be best to qualify some different computational methods than those that have been used at ATR for the past 40 years. This paper discusses two methods of calculating the burnup of ATR fuel elements. The existing method, that uses the PDQ code, is compared to a modern method that uses A General Monte Carlo N-Particle Transport Code (MCNP) combined with the Origen2.2 code. This modern method, MCNP with ORIGEN2.2 (MCWO), is found to give excellent agreement with the existing method (PDQ). Both of MCWO and PDQ are also in a very good agreement to the 235U burnup data generated by an analytical method.

  9. ATR spectra on boundary with mixture containing organic substances

    NASA Astrophysics Data System (ADS)

    Schelokov, R. V.; Yatsishen, V. V.

    2005-02-01

    The problem of not destroying diagnostics and dosing of radiation at laser therapy is one of important in medicine. Therefore the purpose of our work is development of method ATR for diagnostics and researches in biomedicine. In this work as objects of consideration were: a mixture of nicotine with water, a mixture of an ascorbic acid with water and surface lesions of an eye cornea by a herpes virus. Results of our consideration are the ATR spectra defined at different concentration of organic substances and virions.

  10. Analyzing effects of range resolution on MSC HRR ATR performance

    NASA Astrophysics Data System (ADS)

    McWhorter, Todd; Gross, David C.; Hawley, Robert W.; Welsh, Byron M.

    2000-08-01

    This paper is an initial exploration into the effects of range resolution on Automatic Target Recognition (ATR) algorithms based on High Range Resolution (HRR) signatures. The theoretical performance of a two-class, forced-decision classifier is used to quantify the effects of radar resolution on ATR performance. The classifier employed in this study is a forced-decision instantiation of the matched subspace classifier (MSC) developed under the DARPA TRUMPETS program. The paper also examines effects of range resolution on the separability of individual HRR profiles. This work is supported by DARPA/SPO under the MSTAR Enhancements (HBTI) program and in cooperation with AFRL/SNAA.

  11. Investigation of aged Asian dust particles by the combined use of quantitative ED-EPMA and ATR-FTIR imaging

    NASA Astrophysics Data System (ADS)

    Song, Y.-C.; Eom, H.-J.; Jung, H.-J.; Malek, M. A.; Kim, H. K.; Geng, H.; Ro, C.-U.

    2013-03-01

    In our previous works, it was demonstrated that the combined use of quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), which is also known as low-Z particle EPMA, and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) imaging has great potential for a detailed characterization of individual aerosol particles. In this study, extensively chemically modified (aged) individual Asian dust particles collected during an Asian dust storm event on 11 November 2002 in Korea were characterized by the combined use of low-Z particle EPMA and ATR-FTIR imaging. Overall, 109 individual particles were classified into four particle types based on their morphology, elemental concentrations, and molecular species and/or functional groups of individual particles available from the two analytical techniques: Ca-containing (38%), NaNO3-containing (30%), silicate (22%), and miscellaneous particles (10%). Among the 41 Ca-containing particles, 10, 8, and 14 particles contained nitrate, sulfate, and both, respectively, whereas only two particles contained unreacted CaCO3. Airborne amorphous calcium carbonate (ACC) particles were observed in this Asian dust sample for the first time, where their IR peaks for the insufficient symmetric environment of CO32- ions of ACC were clearly differentiated from those of crystalline CaCO3. This paper also reports the first inland field observation of CaCl2 particles probably converted from CaCO3 through the reaction with HCl(g). HCl(g) was likely released from the reaction of sea salt with NOx/HNO3, as all 33 particles of marine origin contained NaNO3 (no genuine sea salt particle was encountered). Some silicate particles with minor amounts of calcium were observed to be mixed with nitrate, sulfate, and water. Among 24 silicate particles, 10 particles are mixed with water, the presence of which could facilitate atmospheric heterogeneous reactions of silicate particles including swelling minerals, such as montmorillonite and vermiculite, and nonswelling ones, such as feldspar and quartz. This paper provides detailed information on the physicochemical characteristics of these aged individual Asia dust particles through the combined use of the two single-particle analytical techniques, and using this analytical methodology it is clearly shown that internal mixing states of the aged particles are highly complicated.

  12. In situ ATR-FTIR studies on MgCl2-diisobutyl phthalate interactions in thin film Ziegler-Natta catalysts.

    PubMed

    Cheruvathur, Ajin V; Langner, Ernie H G; Niemantsverdriet, J W Hans; Thüne, Peter C

    2012-02-01

    To study the surface structure of MgCl(2) support and its interaction with other active components in Ziegler-Natta catalyst, such as electron donors, we prepared a thin film analogue for Ziegler-Natta ethylene polymerization catalyst support by spin-coating a solution of MgCl(2) in ethanol, optionally containing a diester internal donor (diisobutyl-ortho-phthalate, DIBP) on a flat Si crystal surface. The donor content of these films was quantified by applying attenuated total internal reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Changes in the interaction of DIBP with MgCl(2) at various temperatures were monitored by in situ ATR-FTIR. Upon increasing the temperature, a shift in the (C═O) band toward lower wavenumbers was observed together with the depletion of (O-H) stretching band due to the desorption of residual ethanol. We assign this shift to gradual redistribution of adsorbed DIBP from adsorption sites on the MgCl(2) (104) surface toward the more acidic MgCl(2) (110) surface. The morphologies of MgCl(2) and MgCl(2)/DIBP films were studied by transmission electron microscopy (TEM) revealing a preferential orientation of ClMgCl layers (001) parallel to the lateral film dimensions. This orientation becomes more pronounced upon annealing. In the absence of donor, the MgCl(2) grow in to large crystals aligned in large domains upon annealing. Both crystal growth and alignment is impeded by the presence of donor. PMID:22216939

  13. Evaluation of ATR-FTIR spectroscopy with multivariate analysis to study the binding mechanisms of ZnO nanoparticles or Zn2+ to Chelex-100 or metsorb.

    PubMed

    Pouran, Hamid M; Llabjani, Valon; Martin, Francis L; Zhang, Hao

    2013-10-01

    Advancements in nanotechnology and the expected increases in production of commercial products with incorporated manufactured nanomaterials will very likely lead to increasing contamination of nanoparticles (NPs) in the environment. Though studying adverse impacts of NPs in the environment and their ecotoxicological fate and behavior is not new, limited information is available. A major challenge in this respect is the lack of a proper sampling technique that could provide data on concentrations of these materials in the environment. Diffusive gradient in thin-films (DGT) is a well-established method that can measure available concentrations of trace metals in soils and waters. Using this approach, different binding resins are employed as a sink to collect targeted chemicals during fixed times. Here, we examine the suitability of two common types of the DGT binding agents, commercially available Chelex-100 and Metsorb, to investigate whether these materials could irreversibly retain a model nanoparticle, ZnO, and if so, what would be the difference between bound ZnO NP and Zn(2+) ion. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy was used to study the binding materials before and after exposure to ZnO NP and Zn(2+). Based on computational analysis using principal component analysis and linear discriminant analysis (PCA-LDA), it was demonstrated that both Chelex-100 and Metsorb form chemical bonds with ZnO NP and Zn(2+), however the binding mechanisms of these zinc species as inferred from their infrared (IR) spectra are statistically different (95% confidence level). The experimental results suggest that the binding resins hold ZnO NP with fewer and weaker chemical bonds compared to Zn(2+). This research shows the potential of the DGT method to measure available concentrations of nanoparticles in the environment and demonstrate how ATR-FTIR spectroscopy, when used with computational analysis, can differentiate between diverse chemical species that are simultaneously retained by the binding layer in a DGT device. PMID:23947918

  14. Role of extracellular polymeric substances in metal ion complexation on Shewanella oneidensis: Batch uptake, thermodynamic modeling, ATR-FTIR, and EXAFS study

    NASA Astrophysics Data System (ADS)

    Ha, Juyoung; Glabert, Alexandre; Spormann, Alfred M.; Brown, Gordon E., Jr.

    2010-01-01

    The effect of cell wall-associated extracellular polymeric substances (EPS) of the Gram-negative bacterium Shewanella oneidensis strain MR-1 on proton, Zn(II), and Pb(II) adsorption was investigated using a combination of titration/batch uptake studies, surface complexation modeling, attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy, and Zn K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. Both unmodified (wild-type (WT) strain) and genetically modified cells with inhibited production of EPS (?EPS strain) were used. Three major types of functional groups (carboxyl, phosphoryl, and amide groups) were identified in both strains using ATR-FITR spectroscopy. Potentiometric titration data were fit using a constant capacitance model (FITEQL) that included these three functional groups. The fit results indicate less interaction of Zn(II) and Pb(II) with carboxyl and amide groups and a greater interaction with phosphoryl groups in the ?EPS strain than in the WT strain. Results from Zn(II) and Pb(II) batch adsorption studies and surface complexation modeling, assuming carboxyl and phosphoryl functional groups, also indicate significantly lower Zn(II) and Pb(II) uptake and binding affinities for the ?EPS strain. Results from Zn K-edge EXAFS spectroscopy show that Zn(II) bonds to phosphoryl and carboxyl ligands in both strains. Based on batch uptake and modeling results and EXAFS spectral analysis, we conclude that the greater amount of EPS in the WT strain enhances Zn(II) and Pb(II) uptake and hinders diffusion of Zn(II) to the cell walls relative to the ?EPS strain.

  15. Adsorption of Organic Matter at Mineral/Water Interfaces: 7. ATR-FTIR and Quantum Chemical Study of Lactate Interactions with Hematite Nanoparticles

    SciTech Connect

    Ha, Juyoung; Yoon, Tae Hyun; Wang, Yingge; Musgrave, Charles B.; Brown, Jr., Gordon E.

    2008-12-04

    The interaction of the l-lactate ion (l-CH{sub 3}CH(OH)COO{sup -}, lact{sup -1}) with hematite ({alpha}-Fe{sub 2}O{sub 3}) nanoparticles (average diameter 11 nm) in the presence of bulk water at pH 5 and 25 C was examined using a combination of (1) macroscopic uptake measurements, (2) in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and (3) density functional theory modeling at the B3LYP/6-31+G* level. Uptake measurements indicate that increasing [lact{sup -1}]{sub (aq)} results in an increase in lact{sup -1} uptake and a concomitant increase in Fe(III) release as a result of the dissolution of the hematite nanoparticles. The ATR-FTIR spectra of aqueous lact{sup -1} and lact{sup -1} adsorbed onto hematite nanoparticles at coverages ranging from 0.52 to 5.21 {mu}mol/m{sup 2} showed significant differences in peak positions and shapes of carboxyl group stretches. On the basis of Gaussian fits of the spectra, we conclude that lact{sup -1} is present as both outer-sphere and inner-sphere complexes on the hematite nanoparticles. No significant dependence of the extent of lact{sup -1} adsorption on background electrolyte concentration was found, suggesting that the dominant adsorption mode for lact{sup -1} is inner sphere under these conditions. On the basis of quantum chemical modeling, we suggest that inner-sphere complexes of lact{sup -1} adsorbed on hematite nanoparticles occur dominantly as monodentate, mononuclear complexes with the hydroxyl functional group pointing away from the Fe(III) center.

  16. Proposal of AAA-battery-size one-shot ATR Fourier spectroscopic imager for on-site analysis: Simultaneous measurement of multi-components with high accuracy

    NASA Astrophysics Data System (ADS)

    Hosono, Satsuki; Qi, Wei; Sato, Shun; Suzuki, Yo; Fujiwara, Masaru; Hiramatsu, Hiroyuki; Suzuki, Satoru; Abeygunawardhana, P. K. W.; Wada, Kenji; Nishiyama, Akira; Ishimaru, Ichiro

    2015-03-01

    For simultaneous measurement of multi-components on-site like factories, the ultra-compact (diameter: 9[mm], length: 45[mm], weight: 200[g]) one-shot ATR (Attenuated Total Reflection) Fourier spectroscopic imager was proposed. Because the proposed one-shot Fourier spectroscopic imaging is based on spatial-phase-shift interferometer, interferograms could be obtained with simple optical configurations. We introduced the transmission-type relativeinclined phase-shifter, that was constructed with a cuboid prism and a wedge prism, onto the optical Fourier transform plane of infinity corrected optical systems. And also, small light-sources and cameras in the mid-infrared light region, whose size are several millimeter on a side, are essential components for the ultra-compact spectroscopic configuration. We selected the Graphite light source (light source area: 1.7×1.7[mm], maker: Hawkeye technologies) whose radiation factor was high. Fortunately, in these days we could apply the cost-effective 2-dimensional light receiving device for smartphone (e.g. product name: LEPTON, maker: FLIR, price: around 400USD). In the case of alcoholic drinks factory, conventionally workers measure glucose and ethanol concentrations by bringing liquid solution back to laboratories every day. The high portable spectroscopy will make it possible to measure multi-components simultaneously on manufacturing scene. But we found experimentally that absorption spectrum of glucose and water and ethanol were overlapped each other in near infrared light region. But for mid-infrared light region, we could distinguish specific absorption peaks of glucose (@10.5[μm]) and ethanol (@11.5[μm]) independently from water absorption. We obtained standard curve between absorption (@9.6[μm]) and ethanol concentration with high correlation coefficient 0.98 successfully by ATR imaging-type 2-dimensional Fourier spectroscopy (wavelength resolution: 0.057[μm]) with the graphite light source (maker: Hawkeye technologies, type: IR-75).

  17. Role of Bi promotion and solvent in platinum-catalyzed alcohol oxidation probed by in situ X-ray absorption and ATR-IR spectroscopy.

    PubMed

    Mondelli, Cecilia; Grunwaldt, Jan-Dierk; Ferri, Davide; Baiker, Alfons

    2010-01-01

    Modification of 5 wt% Pt/Al(2)O(3) by Bi (0.9 wt%) affords a drastic improvement of catalytic activity in the liquid phase aerobic oxidation of benzyl alcohol. The nature of the solvent employed, cyclohexane or toluene, seems to influence the catalytic activity as well. We have investigated the catalysts under working conditions using in situ X-ray absorption spectroscopy (XAS) and attenuated total reflection infrared spectroscopy (ATR-IR), aiming at uncovering the roles of the metal promoter and the reaction medium. XAS confirms that Bi is oxidized more easily than Pt, maintaining the catalytic activity of the metallic Pt sites for a longer period of time. Interestingly, toluene contrary to cyclohexane reduced Pt to a large extent. The freshly reduced noble metal sites seem to directly interact with the solvent, inducing an immediate poisoning of the material and limiting its performance. This behaviour is not observed in the presence of Bi, whose geometric effect (site blocking) is interpreted as additionally limiting the adsorption of toluene and the premature deactivation of Pt. ATR-IR spectroscopy during CO adsorption on Pt and during reaction indicates that Bi is located rather on extended surfaces than on step or kink sites. Side products, CO and benzoate species, appearing during the reaction reveal that the geometric suppression of undesired reactions does not occur to the same extent on Pt-based catalysts as on Pd, suggesting that decarbonylation of the produced aldehyde on Pt may occur also on sites other than the (111) terraces. PMID:21491655

  18. Comparative study of trace element contents in human full-term placenta and fetal membranes by total reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Kubala-Kuku?, A.; Bana?, D.; Braziewicz, J.; Majewska, U.; Pajek, M.

    2003-04-01

    The total reflection X-ray fluorescence (TXRF) method was applied to study the influence of environmental pollution on the contents of trace elements in human full-term placenta and fetal membranes. The samples were collected from the donors living in two regions characterised by different levels of environmental pollution. In this comparative study, based on relatively large (100) populations, the concentrations of approximately 20 trace elements (P-Pb) were determined in the samples. In particular, the paper discusses the role of 'truncation' of measured concentration distribution by the detection limit of the TXRF method in context of comparative studies. First, the importance of the developed method of reconstruction of original concentration distribution, to derive the correct concentrations of trace elements, is described and demonstrated and, second, the statistical tests, which can be used to compare the truncated, or reconstructed, concentration distributions are discussed. Finally, the statistically significant differences of trace element concentrations found in both populations are presented and summarised.

  19. Unit Title: Imaging the Insertion of Superecliptic pHluorin Labeled Dopamine D2 Receptor Using Total Internal Reflection Fluorescence Microscopy

    PubMed Central

    Daly, Kathryn M.; Li, Yun; Lin, Da-Ting

    2015-01-01

    A better understanding of mechanisms governing receptor insertion to the plasma membrane (PM) requires an experimental approach with excellent spatial and temporal resolutions. Here we present a strategy that enables dynamic visualization of insertion events for dopamine D2 receptors into the PM. This approach includes tagging a pH-sensitive GFP, superecliptic pHluorin, to the extracellular domain of the receptor. By imaging pHluorin-tagged receptors under total internal reflection fluorescence microscopy (TIRFM), we were able to directly visualize individual receptor insertion events into the PM in cultured neurons. This novel imaging approach can be applied to both secreted proteins and many membrane proteins with an extracellular domain labeled with superecliptic pHluorin, and will ultimately allow for detailed dissections of the key mechanisms governing secretion of soluble proteins or the insertion of different membrane proteins to the PM. PMID:25559003

  20. Determination of trace elements in Syrian medicinal plants and their infusions by energy dispersive X-ray fluorescence and total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Khuder, A.; Sawan, M. Kh.; Karjou, J.; Razouk, A. K.

    2009-07-01

    X-ray fluorescence (XRF) and total-reflection X-ray fluorescence (TXRF) techniques suited well for a multi-element determination of K, Ca, Mn, Fe, Cu, Zn, Rb, and Sr in some Syrian medicinal plant species. The accuracy and the precision of both techniques were verified by analyzing the Standard Reference Materials (SRM) peach-1547 and apple leaves-1515. A good agreement between the measured concentrations of the previously mentioned elements and the certified values were obtained with errors less than 10.7% for TXRF and 15.8% for XRF. The determination of Br was acceptable only by XRF with an error less than 24%. Furthermore, the XRF method showed a very good applicability for the determination of K, Ca, Mn, Fe, Cu, Zn, Rb, Sr, and Br in infusions of different Syrian medicinal plant species, namely anise ( Anisum vulgare), licorice root ( Glycyrrhiza glabra), and white wormwood ( Artemisia herba-alba).