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Sample records for diffusion ordered spectroscopy

  1. Characterizations of Some N-Substituted-salicylhydrazide in Mixtures by NMR Diffusion Ordered Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    张芳; 于贤勇; 陈忠; 林深; 刘世雄

    2003-01-01

    Several novel N-substituted-salicylhydrazide ligands, most of which are difficult to be purified or recrystallized so that their chemical configurations can not be confirmed by conventional NMR and/or X-ray diffraction techniques, were synthesized in this experiment, and their chemical configurations in mixture were analyzed and characterized by 2D NMR diffusion ordered spectroscopy (DOSY), a labor-saving virtual separation based on diffusion properties,together with several routine NMR techniques.

  2. High-resolution NMR and diffusion-ordered spectroscopy of port wine.

    Science.gov (United States)

    Nilsson, Mathias; Duarte, Iola F; Almeida, Cláudia; Delgadillo, Ivonne; Goodfellow, Brian J; Gil, Ana M; Morris, Gareth A

    2004-06-16

    The use of high-resolution NMR and high-resolution diffusion-ordered spectroscopy (DOSY) for the characterization of selected Port wine samples of different ages with the aim of identifying changes in composition is described. Conventional 1D and 2D NMR methods enabled the identification of about 35 compounds, including minor components such as some medium-chain alcohols, amino acids, and organic acids. High-resolution (HR) DOSY extended sample characterization, increasing the number of compounds identified and NMR assignments made, by providing information on the relative molecular sizes of the metabolites present. Port wines of different ages were found to differ mainly in their content of (a) organic acids and some amino acids, (b) an unidentified possible disaccharide, and (c) large aromatic species. The relative amount of these last high Mw aromatics is seen to decrease significantly in the oldest wine, as expected from the known formation and precipitation of anthocyanin-based polymers during red wine aging.

  3. Improved compositional analysis of block copolymers using diffusion ordered NMR spectroscopy.

    Science.gov (United States)

    Viel, Stéphane; Mazarin, Michaël; Giordanengo, Rémi; Phan, Trang N T; Charles, Laurence; Caldarelli, Stefano; Bertin, Denis

    2009-11-03

    Block copolymers constitute a fascinating class of polymeric materials that are used in a broad range of applications. The performance of these materials is highly coupled to the physical and chemical properties of the constituting block copolymers. Traditionally, the composition of block copolymers is obtained by 1H NMR spectroscopy on purified copolymer fractions. Specifically, the integrals of a properly selected set of 1H resonances are compared and used to infer the number average molecular weight (M(n)) of one of the block from the (typically known) M(n) value of the other. As a corollary, compositional determinations achieved on imperfectly purified samples lead to serious errors, especially when isolation of the block copolymer from the initial macro initiator is tedious. This investigation shows that Diffusion Ordered NMR Spectroscopy (DOSY) can be used to provide a way to assess the advancement degree of the copolymerization purification/reaction, in order to optimize it and hence contribute to an improved compositional analysis of the resulting copolymer. To this purpose, a series of amphiphilic polystyrene-b-poly(ethylene oxide) block copolymers, obtained by controlled free-radical nitroxide mediated polymerization, were analyzed and it is shown that, under proper experimental conditions, DOSY allows for an improved compositional analysis of these block copolymers.

  4. Characterization of titanium dioxide nanoparticles dispersed in organic ligand solutions by using a diffusion-ordered spectroscopy-based strategy.

    Science.gov (United States)

    Van Lokeren, Luk; Maheut, Géraldine; Ribot, François; Escax, Virginie; Verbruggen, Ingrid; Sanchez, Clément; Martins, José C; Biesemans, Monique; Willem, Rudolph

    2007-01-01

    Diffusion-ordered NMR spectroscopy (DOSY NMR) is presented as a tool for the determination of the diffusion coefficients of organic ligands in suspensions of titanium dioxide nanoparticles. The nanoparticles were prepared by a sol-gel process by hydrolysis and condensation reactions of titanium tetra-n-butoxide in the presence of pentane-2,4-dione (acacH: acetylacetone), as well as para-toluenesulfonic acid (pTsA) and n-butanol (nBuOH). NMR spectroscopic studies were performed in various deuterated solvents, on both dispersed xerosols and diluted sols. The bipolar-pulsed field gradient longitudinal eddy-current delay (LED) pulse sequence was used for data acquisition. The data were processed by inverse Laplace transformation (ILT), by using a maximum entropy algorithm, to afford 2D DOSY spectra. Different diffusion regimes for organic ligands in the bound and unbound states were successfully discriminated, more particularly in [D3]acetonitrile, thus allowing assessment of their interactions with the nanoparticles.

  5. Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)

    Science.gov (United States)

    Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.

    2011-01-01

    Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and…

  6. Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)

    Science.gov (United States)

    Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.

    2011-01-01

    Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and…

  7. Monitoring the functionalization of single-walled carbon nanotubes with chitosan and folic acid by two-dimensional diffusion-ordered nmr spectroscopy

    DEFF Research Database (Denmark)

    Castillo, John J.; Torres, Mary H.; Molina, Daniel R.

    2012-01-01

    A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate that was......A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate...... that was generated by the linkage between the carboxyl moiety of the folic acid and the amino group of the chitosan, which in turn was non-covalently bound to the single-walled carbon nanotubes. The obtained diffusion coefficient values demonstrated that free folic acid diffused more rapidly than the folic acid...... conjugated to single-walled carbon nanotubes-chitosan. The values of the proton signal of hydrogen-1 nuclear magnetic resonance spectroscopy and two-dimensional hydrogen-1 nuclear magnetic resonance spectroscopy further confirmed that the folic acid was conjugated to the chitosan, wrapping the single...

  8. Diffusion measurements by Raman spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Shapiro, Alexander; Berg, Rolf W.;

    Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt......Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt...

  9. Diffusion measurements by Raman spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Shapiro, Alexander; Berg, Rolf W.

    Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt......Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt...

  10. Feasibility study for the rapid screening of target molecules using translational diffusion coefficients: diffusion-ordered NMR spectroscopy of biological toxins.

    Science.gov (United States)

    Henderson, Terry J

    2010-02-01

    A panel of 15 biological toxins ranging between approximately 60-28,000 g/mol was used to evaluate the feasibility of screening aqueous samples for toxin analytes based on their translational diffusion coefficients, D(t). Toxin D(t) values were measured by pulsed-field gradient (1)H NMR spectroscopy using a bipolar pulse pair, longitudinal eddy current delay pulse sequence incorporating water suppression to achieve the maximum dynamic range for toxin signals. To collect data for an effective screening protocol, reference D(t) values were determined from five independent measurements at both 25 and 37 degrees C for all toxins in the panel. In the protocol, D(t) values are measured at both temperatures for a suspected toxin target in a sample, and for assignment as a potential toxin analyte, the measurements are required to fall within +/-0.25 x 10(-6) cm(2)/s of both reference D(t) values for at least one toxin in the panel. Only solution viscosity was found to influence sample D(t) measurements appreciably; however, the measurements are easily corrected for viscosity effects by calculating the D(t) value of the suspected toxin at infinite dilution. In conclusion, the protocol provides a rapid and effective means for screening aqueous samples for all toxins in the panel, narrowing toxin identification to < or = 2 possibilities in virtually all cases.

  11. Fluorescence Correlation Spectroscopy and Nonlinear Stochastic Reaction-Diffusion

    CERN Document Server

    Del Razo, Mauricio J; Qian, Hong; Lin, Guang

    2014-01-01

    The currently existing theory of fluorescence correlation spectroscopy(FCS) is based on the linear fluctuation theory originally developed by Einstein, Onsager, Lax, and others as a phenomenological approach to equilibrium fluctuations in bulk solutions. For mesoscopic reaction-diffusion systems with nonlinear chemical reactions among a small number of molecules, a situation often encountered in single-cell biochemistry, it is expected that FCS time correlation functions of a reaction-diffusion system can deviate from the classic results of Elson and Magde. We first discuss this nonlinear effect for reaction systems without diffusion. For nonlinear stochastic reaction-diffusion systems here are no closed solutions; therefore, stochastic Monte-Carlo simulations are carried out. We show that the deviation is small for a simple bimolecular reaction; the most significant deviations occur when the number of molecules is small and of the same order. Our results show that current linear FCS theory could be adequate ...

  12. Mid infrared upconversion spectroscopy using diffuse reflectance

    Science.gov (United States)

    Sanders, Nicolai; Kehlet, Louis; Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Beato, Pablo; Pedersen, Christian

    2014-02-01

    We present a novel approach for mid infrared (mid-IR) spectral analysis using upconversion technology applied in a diffuse reflectance setup. We demonstrate experimentally that mid-IR spectral features in the 2.6-4 μm range using different test samples (e.g. zeolites) can be obtained. The results are in good agreement with published data. We believe that the benefit of low noise upconversion methods combined with spectral analysis will provide an alternative approach to e.g. mid-IR Fourier Transform microscopy. We discuss in detail the experimental aspects of the proposed method. The upconversion unit consists of a PP:LN crystal situated as an intracavity component in a Nd:YVO4 laser. Mixing incoming spectrally and spatially incoherent light from the test sample with the high power intracavity beam of the Nd:YVO4 laser results in enhanced conversion efficiency. The upconverted light is spectrally located in the near infrared (NIR) wavelength region easily accessible for low noise Silicon CCD camera technology. Thus the room temperature upconversion unit and the Silicon CCD camera replaces noisy mid infrared detectors used in existing Fourier Transform Infrared Spectroscopy. We demonstrate specifically that upconversion methods can be deployed using a diffuse reflectance setup where the test sample is irradiated by a thermal light source, i.e. a globar. The diffuse reflectance geometry is particularly well suited when a transmission setup cannot be used. This situation may happen for highly scattering or absorbing samples.

  13. Mid infrared upconversion spectroscopy using diffuse reflectance

    DEFF Research Database (Denmark)

    Sanders, Nicolai Højer; Kehlet, Louis M.; Dam, Jeppe Seidelin

    2014-01-01

    We present a novel approach for mid infrared (mid-IR) spectral analysis using upconversion technology applied in a diffuse reflectance setup. We demonstrate experimentally that mid-IR spectral features in the 2.6-4 μm range using different test samples (e.g. zeolites) can be obtained. The results...... are in good agreement with published data. We believe that the benefit of low noise upconversion methods combined with spectral analysis will provide an alternative approach to e.g. mid-IR Fourier Transform microscopy. We discuss in detail the experimental aspects of the proposed method. The upconversion unit...... located in the near infrared (NIR) wavelength region easily accessible for low noise Silicon CCD camera technology. Thus the room temperature upconversion unit and the Silicon CCD camera replaces noisy mid infrared detectors used in existing Fourier Transform Infrared Spectroscopy. We demonstrate...

  14. Diffusing-wave spectroscopy of nonergodic media

    Energy Technology Data Exchange (ETDEWEB)

    Scheffold, F.; Skipetrov, S. E.; Romer, S.; Schurtenberger, P.

    2001-06-01

    We introduce an elegant method that allows the application of diffusing-wave spectroscopy (DWS) to nonergodic, solidlike samples. The method is based on the idea that light transmitted through a sandwich of two turbid cells can be considered ergodic even though only the second cell is ergodic. If absorption and/or leakage of light take place at the interface between the cells, we establish a so-called {open_quotes}multiplication rule,{close_quotes} which relates the intensity autocorrelation function of light transmitted through the double-cell sandwich to the autocorrelation functions of individual cells by a simple multiplication. To test the proposed method, we perform a series of DWS experiments using colloidal gels as model nonergodic media. Our experimental data are consistent with the theoretical predictions, allowing quantitative characterization of nonergodic media and demonstrating the validity of the proposed technique.

  15. Nonlocal diffusion second order partial differential equations

    Science.gov (United States)

    Benedetti, I.; Loi, N. V.; Malaguti, L.; Taddei, V.

    2017-02-01

    The paper deals with a second order integro-partial differential equation in Rn with a nonlocal, degenerate diffusion term. Nonlocal conditions, such as the Cauchy multipoint and the weighted mean value problem, are investigated. The existence of periodic solutions is also studied. The dynamic is transformed into an abstract setting and the results come from an approximation solvability method. It combines a Schauder degree argument with an Hartman-type inequality and it involves a Scorza-Dragoni type result. The compact embedding of a suitable Sobolev space in the corresponding Lebesgue space is the unique amount of compactness which is needed in this discussion. The solutions are located in bounded sets and they are limits of functions with values in finitely dimensional spaces.

  16. Fluorescence Correlation Spectroscopy and Nonlinear Stochastic Reaction-Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Del Razo, Mauricio; Pan, Wenxiao; Qian, Hong; Lin, Guang

    2014-05-30

    The currently existing theory of fluorescence correlation spectroscopy (FCS) is based on the linear fluctuation theory originally developed by Einstein, Onsager, Lax, and others as a phenomenological approach to equilibrium fluctuations in bulk solutions. For mesoscopic reaction-diffusion systems with nonlinear chemical reactions among a small number of molecules, a situation often encountered in single-cell biochemistry, it is expected that FCS time correlation functions of a reaction-diffusion system can deviate from the classic results of Elson and Magde [Biopolymers (1974) 13:1-27]. We first discuss this nonlinear effect for reaction systems without diffusion. For nonlinear stochastic reaction-diffusion systems there are no closed solutions; therefore, stochastic Monte-Carlo simulations are carried out. We show that the deviation is small for a simple bimolecular reaction; the most significant deviations occur when the number of molecules is small and of the same order. Extending Delbrück-Gillespie’s theory for stochastic nonlinear reactions with rapidly stirring to reaction-diffusion systems provides a mesoscopic model for chemical and biochemical reactions at nanometric and mesoscopic level such as a single biological cell.

  17. Hydrogen tracer diffusion in LiBH4 measured by spatially resolved Raman spectroscopy.

    Science.gov (United States)

    Borgschulte, A; Gremaud, R; Łodziana, Z; Züttel, A

    2010-05-21

    The hydrogen tracer diffusion in LiBH(4) has been determined by spatially resolved Raman spectroscopy. The measurements give direct evidence of a macroscopic diffusion of BH ions as well as atomic exchange of hydrogen between the anions. An effective tracer diffusion coefficient of deuterium in LiBH(4) of D approximately 7 x 10(-14) m(2) s(-1) at 473 K is derived. The direct exchange rate of hydrogen between BH(4) units is 10 orders of magnitude slower, i.e. the relatively fast effective hydrogen diffusion has its origin in the fast diffusion of BH(4) units.

  18. Correlation of proton MR spectroscopy and diffusion tensor imaging

    NARCIS (Netherlands)

    Irwan, R; Sijens, PE; Potze, JH; Oudkerk, M

    2005-01-01

    Proton magnetic resonance spectroscopy (H-1-MRS) provides indices of neuronal damage. Diffusion tensor imaging (DTI) relates to water diffusivity and fiber tract orientation. A method to compare H-1-MRS and DTI findings was developed, tested on phantom and applied on normal brain. Point-resolved spe

  19. Distributed-order diffusion equations and multifractality: Models and solutions

    Science.gov (United States)

    Sandev, Trifce; Chechkin, Aleksei V.; Korabel, Nickolay; Kantz, Holger; Sokolov, Igor M.; Metzler, Ralf

    2015-10-01

    We study distributed-order time fractional diffusion equations characterized by multifractal memory kernels, in contrast to the simple power-law kernel of common time fractional diffusion equations. Based on the physical approach to anomalous diffusion provided by the seminal Scher-Montroll-Weiss continuous time random walk, we analyze both natural and modified-form distributed-order time fractional diffusion equations and compare the two approaches. The mean squared displacement is obtained and its limiting behavior analyzed. We derive the connection between the Wiener process, described by the conventional Langevin equation and the dynamics encoded by the distributed-order time fractional diffusion equation in terms of a generalized subordination of time. A detailed analysis of the multifractal properties of distributed-order diffusion equations is provided.

  20. Diffusion measurements in binary liquid mixtures by Raman spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Hansen, Susanne Brunsgaard; Shapiro, Alexander

    2007-01-01

    It is shown that Raman spectroscopy allows determination of the molar fractions in mixtures subjected to molecular diffusion. Spectra of three binary systems, benzene/n-hexane, benzene/cyclohexane, and benzene/ acetone, were obtained during vertical (exchange) diffusion at several different heights...... in the literature were found, even in a thermostatically controlled diffusion cell, recording spectra through circulating water. For the system benzene/acetone, the determined diffusion coefficients were in good agreement with the literature data. The limitations of the Raman method are discussed...

  1. Higher Order and Fractional Diffusive Equations

    Directory of Open Access Journals (Sweden)

    D. Assante

    2015-07-01

    Full Text Available We discuss the solution of various generalized forms of the Heat Equation, by means of different tools ranging from the use of Hermite-Kampé de Fériet polynomials of higher and fractional order to operational techniques. We show that these methods are useful to obtain either numerical or analytical solutions.

  2. A variable-order fractal derivative model for anomalous diffusion

    Directory of Open Access Journals (Sweden)

    Liu Xiaoting

    2017-01-01

    Full Text Available This paper pays attention to develop a variable-order fractal derivative model for anomalous diffusion. Previous investigations have indicated that the medium structure, fractal dimension or porosity may change with time or space during solute transport processes, results in time or spatial dependent anomalous diffusion phenomena. Hereby, this study makes an attempt to introduce a variable-order fractal derivative diffusion model, in which the index of fractal derivative depends on temporal moment or spatial position, to characterize the above mentioned anomalous diffusion (or transport processes. Compared with other models, the main advantages in description and the physical explanation of new model are explored by numerical simulation. Further discussions on the dissimilitude such as computational efficiency, diffusion behavior and heavy tail phenomena of the new model and variable-order fractional derivative model are also offered.

  3. Theoretical model of blood flow measurement by diffuse correlation spectroscopy

    Science.gov (United States)

    Sakadžić, Sava; Boas, David A.; Carp, Stefan

    2017-02-01

    Diffuse correlation spectroscopy (DCS) is a noninvasive method to quantify tissue perfusion from measurements of the intensity temporal autocorrelation function of diffusely scattered light. However, DCS autocorrelation function measurements in tissue better match theoretical predictions based on the diffusive motion of the scatterers than those based on a model where the advective nature of blood flow dominates the stochastic properties of the scattered light. We have recently shown using Monte Carlo (MC) simulations and assuming a simplistic vascular geometry and laminar flow profile that the diffusive nature of the DCS autocorrelation function decay is likely a result of the shear-induced diffusion of the red blood cells. Here, we provide theoretical derivations supporting and generalizing the previous MC results. Based on the theory of diffusing-wave spectroscopy, we derive an expression for the autocorrelation function along the photon path through a vessel that takes into account both diffusive and advective scatterer motion, and we provide the solution for the DCS autocorrelation function in a semi-infinite geometry. We also derive the correlation diffusion and correlation transfer equation, which can be applied for an arbitrary sample geometry. Further, we propose a method to take into account realistic vascular morphology and flow profile.

  4. A Simplified Algorithm for Inverting Higher Order Diffusion Tensors

    Directory of Open Access Journals (Sweden)

    Laura Astola

    2014-11-01

    Full Text Available In Riemannian geometry, a distance function is determined by an inner product on the tangent space. In Riemann–Finsler geometry, this distance function can be determined by a norm. This gives more freedom on the form of the so-called indicatrix or the set of unit vectors. This has some interesting applications, e.g., in medical image analysis, especially in diffusion weighted imaging (DWI. An important application of DWI is in the inference of the local architecture of the tissue, typically consisting of thin elongated structures, such as axons or muscle fibers, by measuring the constrained diffusion of water within the tissue. From high angular resolution diffusion imaging (HARDI data, one can estimate the diffusion orientation distribution function (dODF, which indicates the relative diffusivity in all directions and can be represented by a spherical polynomial. We express this dODF as an equivalent spherical monomial (higher order tensor to directly generalize the (second order diffusion tensor approach. To enable efficient computation of Riemann–Finslerian quantities on diffusion weighted (DW-images, such as the metric/norm tensor, we present a simple and efficient algorithm to invert even order spherical monomials, which extends the familiar inversion of diffusion tensors, i.e., symmetric matrices.

  5. Variable order differential equations with piecewise constant order-function and diffusion with changing modes

    CERN Document Server

    Umarov, Sabir

    2009-01-01

    In this paper diffusion processes with changing modes are studied involving the variable order partial differential equations. We prove the existence and uniqueness theorem of a solution of the Cauchy problem for fractional variable order (with respect to the time derivative) pseudo-differential equations. Depending on the parameters of variable order derivatives short or long range memories may appear when diffusion modes change. These memory effects are classified and studied in detail. Processes that have distinctive regimes of different types of diffusion depending on time are ubiquitous in the nature. Examples include diffusion in a heterogeneous media and protein movement in cell biology.

  6. An explicit high order method for fractional advection diffusion equations

    Science.gov (United States)

    Sousa, Ercília

    2014-12-01

    We propose a high order explicit finite difference method for fractional advection diffusion equations. These equations can be obtained from the standard advection diffusion equations by replacing the second order spatial derivative by a fractional operator of order α with 1convergence of the numerical method through consistency and stability. The order of convergence varies between two and three and for advection dominated flows is close to three. Although the method is conditionally stable, the restrictions allow wide stability regions. The analysis is confirmed by numerical examples.

  7. Establishing the diffuse correlation spectroscopy signal relationship with blood flow.

    Science.gov (United States)

    Boas, David A; Sakadžić, Sava; Selb, Juliette; Farzam, Parisa; Franceschini, Maria Angela; Carp, Stefan A

    2016-07-01

    Diffuse correlation spectroscopy (DCS) measurements of blood flow rely on the sensitivity of the temporal autocorrelation function of diffusively scattered light to red blood cell (RBC) mean square displacement (MSD). For RBCs flowing with convective velocity [Formula: see text], the autocorrelation is expected to decay exponentially with [Formula: see text], where [Formula: see text] is the delay time. RBCs also experience shear-induced diffusion with a diffusion coefficient [Formula: see text] and an MSD of [Formula: see text]. Surprisingly, experimental data primarily reflect diffusive behavior. To provide quantitative estimates of the relative contributions of convective and diffusive movements, we performed Monte Carlo simulations of light scattering through tissue of varying vessel densities. We assumed laminar vessel flow profiles and accounted for shear-induced diffusion effects. In agreement with experimental data, we found that diffusive motion dominates the correlation decay for typical DCS measurement parameters. Furthermore, our model offers a quantitative relationship between the RBC diffusion coefficient and absolute tissue blood flow. We thus offer, for the first time, theoretical support for the empirically accepted ability of the DCS blood flow index ([Formula: see text]) to quantify tissue perfusion. We find [Formula: see text] to be linearly proportional to blood flow, but with a proportionality modulated by the hemoglobin concentration and the average blood vessel diameter.

  8. Estimating soil quality indicators with diffuse reflectance spectroscopy

    Science.gov (United States)

    Rapid estimation of soil quality is needed for determining and mapping soil variability in site-specific management. One technology that can fulfill this need is diffuse reflectance spectroscopy, which measures light reflected from the soil in the visible and near infrared wavelength bands. Reflecta...

  9. Diffuse reflectance spectroscopy: towards clinical application in breast cancer

    NARCIS (Netherlands)

    Evers, D.J.; Nachabe, R.; Vrancken Peeters, M.J.; Hage, van der J.A.; Oldenburg, H.S.; Rutgers, E.J.; Lucassen, G.W.; Hendriks, B.H.; Wesseling, J.; Ruers, T.J.M.

    2013-01-01

    Diffuse reflectance spectroscopy (DRS) is a promising new technique for breast cancer diagnosis. However, inter-patient variation due to breast tissue heterogeneity may interfere with the accuracy of this technique. To tackle this issue, we aim to determine the diagnostic accuracy of DRS in individu

  10. Interleaving Gradient Magnetic Field Method for Diffusion Weighted Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    GAO Song; ZU Zhong-Liang; BAO Shang-Lian

    2008-01-01

    Diffusion-weighted magnetic resonance spectroscopy(DWS)has considerable potential in clinical and research applications.However.it is seldom implemented in conventional magnetic resonance imaging(MRI)scanners due to the strict hardware requirements.We propose an interleaving gradient magnetic field(IGMF)method based on point resolved spectroscopy(PRESS).Four interlaced powerful diffusion sensitive gradient magnetic fields are positioned around the two πrefocusing rf pulses in the PRESS sequence.This method utilizes the interval time in the PRESS pulse sequence,doubles the duration time of the diffusion sensitive gradient magnetic field and decreases the detrimental effect of the induced eddy current.The results of theoretical analysis and experimental observation demonstrate that the IGMF method is suitable for conventional MRI scanners.

  11. Detection of a diffusive cloak via second-order statistics

    CERN Document Server

    Koirala, Milan

    2016-01-01

    We propose a scheme to detect the diffusive cloak proposed by Schittny et al [Science 345, 427 (2014)]. We exploit the fact that diffusion of light is an approximation that disregards wave interference. The long-range contribution to intensity correlation is sensitive to locations of paths crossings and the interference inside the medium, allowing one to detect the size and position, including the depth, of the diffusive cloak. Our results also suggest that it is possible to separately manipulate the first- and the second-order statistics of wave propagation in turbid media.

  12. Order-disorder phase transition and stress-induced diffusion in Au-Cu

    Science.gov (United States)

    Hennig, John; Mari, Daniele; Schaller, Robert

    2009-04-01

    Isothermal mechanical spectroscopy by means of a forced torsion pendulum (measuring internal friction/mechanical loss) was used to study the interplay of long-range atomic order and stress-induced diffusion (Zener relaxation) in Au57%Cu43% . Our results show that the relaxation strength of stress-induced diffusion exhibits the typical Curie-Weiss-type behavior in the disordered solid solution and then gradually goes to zero below the critical temperature marking the phase transition to the long-range-ordered AuCu II phase. The breakdown of the relaxation peak reflects the kinetics of the ordering process. The diffusion data were used to establish the transformation time vs temperature (TTT) diagram of the phase transformation.

  13. Distributed order reaction-diffusion systems associated with Caputo derivatives

    Science.gov (United States)

    Saxena, R. K.; Mathai, A. M.; Haubold, H. J.

    2014-08-01

    This paper deals with the investigation of the solution of an unified fractional reaction-diffusion equation of distributed order associated with the Caputo derivatives as the time-derivative and Riesz-Feller fractional derivative as the space-derivative. The solution is derived by the application of the joint Laplace and Fourier transforms in compact and closed form in terms of the H-function. The results derived are of general nature and include the results investigated earlier by other authors, notably by Mainardi et al. ["The fundamental solution of the space-time fractional diffusion equation," Fractional Calculus Appl. Anal. 4, 153-202 (2001); Mainardi et al. "Fox H-functions in fractional diffusion," J. Comput. Appl. Math. 178, 321-331 (2005)] for the fundamental solution of the space-time fractional equation, including Haubold et al. ["Solutions of reaction-diffusion equations in terms of the H-function," Bull. Astron. Soc. India 35, 681-689 (2007)] and Saxena et al. ["Fractional reaction-diffusion equations," Astrophys. Space Sci. 305, 289-296 (2006a)] for fractional reaction-diffusion equations. The advantage of using the Riesz-Feller derivative lies in the fact that the solution of the fractional reaction-diffusion equation, containing this derivative, includes the fundamental solution for space-time fractional diffusion, which itself is a generalization of fractional diffusion, space-time fraction diffusion, and time-fractional diffusion, see Schneider and Wyss ["Fractional diffusion and wave equations," J. Math. Phys. 30, 134-144 (1989)]. These specialized types of diffusion can be interpreted as spatial probability density functions evolving in time and are expressible in terms of the H-function in compact forms. The convergence conditions for the double series occurring in the solutions are investigated. It is interesting to observe that the double series comes out to be a special case of the Srivastava-Daoust hypergeometric function of two variables

  14. Diffusive Wave Spectroscopy of a random close packing of spheres

    Science.gov (United States)

    Crassous, J.

    2007-06-01

    We are interested in the propagation of light in a random packing of dielectric spheres within the geometrical optics approximation. Numerical simulations are performed using a ray tracing algorithm. The effective refractive indexes and the transport mean free path are computed for different refractive indexes of spheres and intersticial media. The variations of the optical path length under small deformations of the spheres assembly are also computed and compared to the results of Diffusive Wave Spectroscopy experiments. Finally, we propose a measure of the transport mean free path and a Diffusive Wave Spectroscopy experiment on a packing of glass spheres. The results of those experiments agree with the predictions of this ray tracing approach.

  15. Diffusive wave spectroscopy of a random close packing of spheres.

    Science.gov (United States)

    Crassous, J

    2007-06-01

    We are interested in the propagation of light in a random packing of dielectric spheres within the geometrical optics approximation. Numerical simulations are performed using a ray tracing algorithm. The effective refractive indexes and the transport mean free path are computed for different refractive indexes of spheres and intersticial media. The variations of the optical path length under small deformations of the spheres assembly are also computed and compared to the results of Diffusive Wave Spectroscopy experiments. Finally, we propose a measure of the transport mean free path and a Diffusive Wave Spectroscopy experiment on a packing of glass spheres. The results of those experiments agree with the predictions of this ray tracing approach.

  16. Distributed order reaction-diffusion systems associated with Caputo derivatives

    CERN Document Server

    Saxena, R K; Haubold, H J

    2011-01-01

    This paper deals with the investigation of the solution of an unified fractional reaction-diffusion equation of distributed order associated with the Caputo derivatives as the time-derivative and Riesz-Feller fractional derivative as the space-derivative. The solution is derived by the application of the joint Laplace and Fourier transforms in compact and closed form in terms of the H-function. The results derived are of general nature and include the results investigated earlier by other authors, notably by Mainardi et al. [23,24], for the fundamental solution of the space-time fractional equation, including Haubold et al. [13] and Saxena et al. [38] for fractional reaction-diffusion equations. The advantage of using the Riesz-Feller derivative lies in the fact that the solution of the fractional reaction-diffusion equation, containing this derivative, includes the fundamental solution for space-time fractional diffusion, which itself is a generalization of fractional diffusion, space-time fraction diffusion...

  17. Assessment of sacrococcygeal pressure ulcers using diffuse correlation spectroscopy

    Science.gov (United States)

    Diaz, David; Lafontant, Alec; Neidrauer, Michael; Weingarten, Michael S.; DiMaria-Ghalili, Rose Ann; Fried, Guy W.; Rece, Julianne; Lewin, Peter A.; Zubkov, Leonid

    2016-03-01

    Microcirculation is essential for proper supply of oxygen and nutritive substances to the biological tissue and the removal of waste products of metabolism. The determination of microcirculatory blood flow (mBF) is therefore of substantial interest to clinicians for assessing tissue health; particularly in pressure ulceration and suspected deep tissue injury. The goal of this pilot clinical study was to assess deep-tissue pressure ulceration by non-invasively measuring mBF using Diffuse Correlation Spectroscopy (DCS). DCS provides information about the flow of red blood cells in the capillary network by measuring the temporal autocorrelation function of scattering light intensity. A novel optical probe was developed in order to obtain measurements under the load of the subject's body as pressure is applied (ischemia) and then released (reperfusion) on sacrococcygeal tissue in a hospital bed. Prior to loading measurements, baseline readings of the sacral region were obtained by measuring the subjects in a side-lying position. DCS measurements from the sacral region of twenty healthy volunteers have been compared to those of two patients who initially had similar non-blanchable redness. The temporal autocorrelation function of scattering light intensity of the patient whose redness later disappeared was similar to that of the average healthy subject. The second patient, whose redness developed into an advanced pressure ulcer two weeks later, had a substantial decrease in blood flow while under the loading position compared to healthy subjects. Preliminary results suggest the developed system may potentially predict whether non-blanchable redness will manifest itself as advanced ulceration or dissipate over time.

  18. Correlation of proton MR spectroscopy and diffusion tensor imaging.

    Science.gov (United States)

    Irwan, Roy; Sijens, Paul E; Potze, Jan-Hendrik; Oudkerk, Matthijs

    2005-10-01

    Proton magnetic resonance spectroscopy ((1)H-MRS) provides indices of neuronal damage. Diffusion tensor imaging (DTI) relates to water diffusivity and fiber tract orientation. A method to compare (1)H-MRS and DTI findings was developed, tested on phantom and applied on normal brain. Point-resolved spectroscopy (T(R)/T(E)=1500/135) was used for chemical shift imaging of a supraventricular volume of interest of 8 x 8 x 2 cm(3) (64 voxels). In DTI, a segmental spin-echo sequence (T(R)/T(E)=5500/91) was used and slices were stacked to reproduce the slab used in MRS. The spatial distributions of choline and N-acetylaspartate (NAA) correlated to mean fractional anisotropy and apparent diffusion coefficient (ADC) for the inner 6 x 6=36 voxels defined in MRS, most notably NAA and ADC value (r=-.70, P<.00001; correlation across four subjects, 144 data pairs). This is the first association of neuron metabolite contents in volunteers with structure as indicated by DTI.

  19. Plutonium in monazite and brabantite: Diffuse reflectance spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yingjie [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)], E-mail: yzx@ansto.gov.au; Vance, Eric R. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)

    2008-04-30

    The valence states of plutonium (Pu) in monazite and brabantite have been studied by using diffuse reflectance spectroscopy. In the absence of charge compensators, Pu exists mainly as trivalent ions in air-fired monazites and only trivalent ions in argon-fired monazites. However, with added Ca{sup 2+}/Pb{sup 2+} as charge compensators Pu can exist as tetravalent ions. Published data on absorption spectra of both trivalent and tetravalent Pu ions in the monazite structure have been extended to the mid near infrared region (4000 cm{sup -1})

  20. Fractional diffusion equation and impedance spectroscopy of electrolytic cells.

    Science.gov (United States)

    Lenzi, E K; Evangelista, L R; Barbero, G

    2009-08-20

    The influence of the ions on the electrochemical impedance of a cell is calculated in the framework of a complete model in which the fractional drift-diffusion problem is analytically solved. The resulting distribution of the electric field inside the sample is determined by solving Poisson's equation. The theoretical model to determine the electrical impedance we are proposing here is based on the fractional derivative of distributed order on the diffusion equation. We argue that this is the more convenient and physically significant approach to account for the enormous variety of the diffusive regimes in a real cell. The frequency dependence of the real and imaginary parts of the impedance are shown to be very similar to the ones experimentally obtained in a large variety of electrolytic samples.

  1. Impact of diffusion limited aggregates of impurities on nematic ordering

    Science.gov (United States)

    Harkai, S.; Ambrožič, M.; Kralj, S.

    2017-02-01

    We study the impact of random bond-type disorder on two-dimensional (2D) orientational ordering of nematic liquid crystal (LC) configurations. The lattice Lebwohl-Lasher pseudospin model is used to model orientational ordering perturbed by frozen-in rod-like impurities of concentration p exhibiting the isotropic orientational probability distribution. The impurities are either (i) randomly spatially distributed or (ii) form diffusion limited aggregation (DLA)-type patterns characterized by the fractal dimensions df, where we consider cases df ∼ 1.7 and df ∼ 1.9. The degree of orientational ordering is quantified in terms of the orientational pair correlation function G(r) . Simulations reveal that the DLA pattern imposed disorder has a significantly weaker impact for a given concentration of impurities. Furthermore, if samples are quenched from the isotropic LC phase, then the fractal dimension is relatively strongly imprinted on quantitative characteristics of G(r) .

  2. FRET Fluctuation Spectroscopy of Diffusing Biopolymers: Contributions of Conformational Dynamics and Translational Diffusion

    Science.gov (United States)

    Gurunathan, Kaushik; Levitus, Marcia

    2009-01-01

    The use of Fluorescence Correlation Spectroscopy (FCS) to study conformational dynamics in diffusing biopolymers requires that the contributions to the signal due to translational diffusion are separated from those due to conformational dynamics. A simple approach that has been proposed to achieve this goal involves the analysis of fluctuations in Fluorescence Resonance Energy Transfer (FRET) efficiency. In this work, we investigate the applicability of this methodology by combining Monte Carlo simulations and experiments. Results show that diffusion does not contribute to the measured fluctuations in FRET efficiency in conditions where the relaxation time of the kinetic process is much shorter than the mean transit time of the molecules in the optical observation volume. However, in contrast to what has been suggested in previous work, the contributions of diffusion are otherwise significant. Neglecting the contributions of diffusion can potentially lead to an erroneous interpretation of the kinetic mechanisms. As an example, we demonstrate that the analysis of FRET fluctuations in terms of a purely kinetic model would generally lead to the conclusion that the system presents complex kinetic behavior even for an idealized two-state system PMID:20030305

  3. Does the spectral format matter in diffuse reflection spectroscopy?

    Science.gov (United States)

    Reeves, James B

    2009-06-01

    Near-infrared, and more recently, mid-infrared diffuse reflection spectroscopy (more commonly and erroneously called reflectance spectroscopy) have come to be extensively used to determine the composition of products ranging from forages and drugs to soils. In these methods, spectra are generally collected as reflectance or R and transformed to log (1/reflectance). However, some near-infrared researchers do not transform the data, but use the data directly as reflectance. As it is generally held that procedures such as partial least squares regression do not work well with nonlinear data and the log (1/reflectance) transformation is held to be a best effort at linearization for near-infrared diffuse reflection spectral data, the question arises as to why then does not everyone transform the data? The objective of this work was to investigate this question using near-infrared and mid-infrared spectra in various formats. Calibrations were developed using spectral data from forages in several formats: reflectance, log (1/reflectance), non-background corrected single beam spectra, interferograms, and Kubelka-Munk transformed data. Calibrations were developed using both non-pretreated spectra and using data pretreatments such as derivatives. Results showed that calibrations using partial least squares regression did not require any specific data format. Accurate calibrations were developed for fiber, digestibility, and protein measures in forages using any of the aforementioned spectral formats including non-background-corrected single beam spectra and even interferograms. While calibrations could be developed using any of the formats, results indicated that those using Kubelka-Munk and especially interferograms did not perform as well as the others, although they were still quite good. In conclusion, results using forage spectra indicated that accurate and equivalent calibrations can be developed using diffuse reflectance data, with (reflectance) or without background

  4. High order schemes for the tempered fractional diffusion equations

    CERN Document Server

    Li, Can

    2014-01-01

    L\\'{e}vy flight models whose jumps have infinite moments are mathematically used to describe the superdiffusion in complex systems. Exponentially tempering the probability of large jumps of L\\'{e}vy flights leads to the tempered stable L\\'{e}vy processes which combine both the $\\alpha$-stable and Gaussian trends; and the very large jumps are unlikely and all their moments exist. The probability density functions of the tempered stable L\\'{e}vy processes solve the tempered fractional diffusion equation. This paper focuses on designing the high order difference schemes for the tempered fractional diffusion equation on bounded domain. The high order difference approximations, called the tempered and weighted and shifted Gr\\"{u}nwald difference (tempered-WSGD) operators, in space are obtained by using the properties of the tempered fractional calculus and weighting and shifting their first order Gr\\"{u}nwald type difference approximations. And the Crank-Nicolson discretization is used in the time direction. The s...

  5. Recipes to make organic phantoms for diffusive optical spectroscopy.

    Science.gov (United States)

    Quarto, Giovanna; Pifferi, Antonio; Bargigia, Ilaria; Farina, Andrea; Cubeddu, Rinaldo; Taroni, Paola

    2013-04-10

    Three recipes are presented to make tissue constituent-equivalent phantoms of water and lipids. Different approaches to prepare the emulsion are proposed. Nature phantoms are made using no emulsifying agent, but just a professional disperser; instead Agar and Triton phantoms are made using agar or Triton X-100, respectively, as agents to emulsify water and lipids. Different water-to-lipid ratios ranging from 30% to 70% by mass were tested. A broadband time-resolved diffuse optical spectroscopy system was used to characterize the phantoms in terms of optical properties and composition. For some water/lipid ratios the emulsion fails or the phantom has limited lifetime, but in most cases the recipes provide phantoms with a high degree of homogeneity [coefficient of variation (CV) of 4.6% and 1.5% for the absorption and reduced scattering coefficient, respectively] and good reproducibility (CV of 8.3% and 12.4% for absorption and reduced scattering coefficient, respectively).

  6. A scalable correlator for multichannel diffuse correlation spectroscopy

    Science.gov (United States)

    Stapels, Christopher J.; Kolodziejski, Noah J.; McAdams, Daniel; Podolsky, Matthew J.; Fernandez, Daniel E.; Farkas, Dana; Christian, James F.

    2016-03-01

    Diffuse correlation spectroscopy (DCS) is a technique which enables powerful and robust non-invasive optical studies of tissue micro-circulation and vascular blood flow. The technique amounts to autocorrelation analysis of coherent photons after their migration through moving scatterers and subsequent collection by single-mode optical fibers. A primary cost driver of DCS instruments are the commercial hardware-based correlators, limiting the proliferation of multi-channel instruments for validation of perfusion analysis as a clinical diagnostic metric. We present the development of a low-cost scalable correlator enabled by microchip-based time-tagging, and a software-based multi-tau data analysis method. We will discuss the capabilities of the instrument as well as the implementation and validation of 2- and 8-channel systems built for live animal and pre-clinical settings.

  7. Effects of probe geometry on transscleral diffuse optical spectroscopy.

    Science.gov (United States)

    Svenmarker, Pontus; Xu, Can T; Andersson-Engels, Stefan; Krohn, Jørgen

    2011-11-01

    The purpose of this study was to investigate how the geometry of a fiber optic probe affects the transmission and reflection of light through the scleral eye wall. Two geometrical parameters of the fiber probe were investigated: the source-detector distance and the fiber protrusion, i.e. the length of the fiber extending from the flat surface of the fiber probe. For optimization of the fiber optic probe geometry, fluorescence stained choroidal tumor phantoms in ex vivo porcine eyes were measured with both diffuse reflectance- and laser-induced fluorescence spectroscopy. The strength of the fluorescence signal compared to the excitation signal was used as a measure for optimization. Intraocular pressure (IOP) and temperature were monitored to assess the impact of the probe on the eye. For visualizing any possible damage caused by the probe, the scleral surface was imaged with scanning electron microscopy after completion of the spectroscopic measurements. A source-detector distance of 5 mm with zero fiber protrusion was considered optimal in terms of spectroscopic contrast, however, a slight fiber protrusion of 0.5 mm is argued to be advantageous for clinical measurements. The study further indicates that transscleral spectroscopy can be safely performed in human eyes under in vivo conditions, without leading to an unacceptable IOP elevation, a significant rise in tissue temperature, or any visible damage to the scleral surface.

  8. Diffusion-Weighted Images Superresolution Using High-Order SVD.

    Science.gov (United States)

    Wu, Xi; Yang, Zhipeng; Hu, Jinrong; Peng, Jing; He, Peiyu; Zhou, Jiliu

    2016-01-01

    The spatial resolution of diffusion-weighted imaging (DWI) is limited by several physical and clinical considerations, such as practical scanning times. Interpolation methods, which are widely used to enhance resolution, often result in blurred edges. Advanced superresolution scanning acquires images with specific protocols and long acquisition times. In this paper, we propose a novel single image superresolution (SR) method which introduces high-order SVD (HOSVD) to regularize the patch-based SR framework on DWI datasets. The proposed method was implemented on an adaptive basis which ensured a more accurate reconstruction of high-resolution DWI datasets. Meanwhile, the intrinsic dimensional decreasing property of HOSVD is also beneficial for reducing the computational burden. Experimental results from both synthetic and real DWI datasets demonstrate that the proposed method enhances the details in reconstructed high-resolution DWI datasets and outperforms conventional techniques such as interpolation methods and nonlocal upsampling.

  9. Discerning Aggregation in Homogeneous Ensembles: A General Description of Photon Counting Spectroscopy in Diffusing Systems

    CERN Document Server

    Ren, H; Altan-Bonnet, G; Libchaber, A; Ren, Hai-cang; Goddard, Noel L.; Altan-Bonnet, Gregoire; Libchaber, Albert

    2004-01-01

    In order to discern aggregation in solutions, we present a quantum mechanical analog of the photon statistics from fluorescent molecules diffusing through a focused beam. A generating functional is developed to fully describe the experimental physical system as well as the statistics. Histograms of the measured time delay between photon counts are fit by an analytical solution describing the static as well as diffusing regimes. To determine empirical fitting parameters, fluorescence correlation spectroscopy is used in parallel to the photon counting. For expedient analysis, we find that the distribution's deviation from a single Poisson shows a difference between two single fluor moments or a double fluor aggregate of the same total intensities. Initial studies were performed on fixed-state aggregates limited to dimerization. However preliminary results on reactive species suggest that the method can be used to characterize any aggregating system.

  10. In vivo diffuse correlation spectroscopy investigation of the ocular fundus

    Science.gov (United States)

    Cattini, Stefano; Staurenghi, Giovanni; Gatti, Antonietta; Rovati, Luigi

    2013-05-01

    Diffuse correlation spectroscopy (DCS) measurements in vivo recorded from rabbits' ocular fundus are presented. Despite the complexity of these ocular tissues, we provide a clear and simple demonstration of the DCS abilities to analyze variations in physiological quantities of clinical interest. Indeed, the reported experimental activities demonstrate that DCS can reveal both choroidal-flow and temperature variations and detect nano- and micro-aggregates in ocular fundus circulation. Such abilities can be of great interest both in fundamental research and practical clinical applications. The proposed measuring system can be useful in: (a) monitoring choroidal blood flow variations, (b) determining the end-point for photo-dynamic therapy and transpupillary thermo therapy and, (c) managing the dye injection and determining an end-point for dye-enhanced photothrombosis. Moreover, it could allow both diagnoses when the presence of nano- and micro-aggregates is related to specific diseases and verifying the effects of nanoparticle injection in nanomedicine. Even though the reported results demonstrate the applicability of DCS to investigate ocular fundus, a detailed and accurate investigation of the limits of detection is beyond the scope of this article.

  11. Evaluation of emulsion stability by diffuse reflectance spectroscopy.

    Science.gov (United States)

    Akers, M J; Lach, J L

    1976-02-01

    A new method is described for evaluating the stability of emulsion bases and active components contained within such emulsions. Diffuse reflectance spectroscopy (DRS) is a technique that has the capability of detecting changes in particle size, surface properties, or drug quality of emulsions as a function of time without disturbance of the system. Such physical or chemical changes are monitored by changes in the visible and UV wavelength spectral characteristics of the emulsified systems. Four basic emulsion systems were prepared and analyzed for physical stability for 6 months by three techniques: visible coalescence, particle counting measurement, and DRS. Two drugs, aspirin and ascorbic acid, were then incorporated within stable emulsion bases, and the chemical stability of these drugs was monitored by DRS for 6 months. Results were compared with concomitant quantitative drug assay procedures. Good agreement was observed when data from DRS and analytical measurements were compared. The DRS technique may be used as a supportive method, offering simplicity and expedience, with other methods of evaluating emulsion stability and drug stability within emulsified systems.

  12. Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

    Science.gov (United States)

    Zonios, George; Dimou, Aikaterini; Galaris, Dimitrios

    2008-01-01

    Hydrogen peroxide is an important oxidizing agent in biological systems. In dermatology, it is frequently used as topical antiseptic, it has a haemostatic function, it can cause skin blanching, and it can facilitate skin tanning. In this work, we investigated skin interaction with hydrogen peroxide, non-invasively, using diffuse reflectance spectroscopy. We observed transient changes in the oxyhaemoglobin and deoxyhaemoglobin concentrations as a result of topical application of dilute H2O2 solutions to the skin, with changes in deoxyhaemoglobin concentration being more pronounced. Furthermore, we did not observe any appreciable changes in melanin absorption properties as well as in the skin scattering properties. We also found no evidence for production of oxidized haemoglobin forms. Our observations are consistent with an at least partial decomposition of hydrogen peroxide within the stratum corneum and epidermis, with the resulting oxygen and/or remaining hydrogen peroxide inducing vasoconstriction to dermal blood vessels and increasing haemoglobin oxygen saturation. An assessment of the effects of topical application of hydrogen peroxide to the skin may serve as the basis for the development of non-invasive techniques to measure skin antioxidant capacity and also may shed light onto skin related disorders such as vitiligo.

  13. Probing skin interaction with hydrogen peroxide using diffuse reflectance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zonios, George [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Dimou, Aikaterini [Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina (Greece); Galaris, Dimitrios [Laboratory of Biological Chemistry, School of Medicine, University of Ioannina, 45110 Ioannina (Greece)

    2008-01-07

    Hydrogen peroxide is an important oxidizing agent in biological systems. In dermatology, it is frequently used as topical antiseptic, it has a haemostatic function, it can cause skin blanching, and it can facilitate skin tanning. In this work, we investigated skin interaction with hydrogen peroxide, non-invasively, using diffuse reflectance spectroscopy. We observed transient changes in the oxyhaemoglobin and deoxyhaemoglobin concentrations as a result of topical application of dilute H{sub 2}O{sub 2} solutions to the skin, with changes in deoxyhaemoglobin concentration being more pronounced. Furthermore, we did not observe any appreciable changes in melanin absorption properties as well as in the skin scattering properties. We also found no evidence for production of oxidized haemoglobin forms. Our observations are consistent with an at least partial decomposition of hydrogen peroxide within the stratum corneum and epidermis, with the resulting oxygen and/or remaining hydrogen peroxide inducing vasoconstriction to dermal blood vessels and increasing haemoglobin oxygen saturation. An assessment of the effects of topical application of hydrogen peroxide to the skin may serve as the basis for the development of non-invasive techniques to measure skin antioxidant capacity and also may shed light onto skin related disorders such as vitiligo.

  14. Study on the Interaction betweenβ3-Cyclodextrin and Naproxen by Two-dimensional Diffusion Ordered NMR Spectroscopy%二维扩散排序核磁共振谱法研究β-环糊精/萘普生的相互作用

    Institute of Scientific and Technical Information of China (English)

    陈昌国; 张明明; 刘渝萍

    2011-01-01

    采用二维扩散排序(DOSY)核磁共振法研究了萘普生与β-环糊精的相互作用,考察了不同包合因素对主客体自扩散系数及平衡常数的影响,并对萘普生与β-环糊精包合反应进行了热力学分析,以揭示萘普生与β-环糊精的包合反应机理.实验结果表明,温度、水含量、溶液pH值、离子强度等对客体萘普生的自扩散系数影响较大,但对主体环糊精自扩散系数的影响甚微;以上参数的增加均会使得平衡常数增大,有利于包合反应的进行,且在pH9.0时包合作用最强;热力学参数进一步表明萘普生与环糊精的包合反应为自发吸热的熵驱动过程,主要作用为疏水力.%The interaction between naproxen and cyclodextrin was studied by two-dimensional diffusion ordered ( 2D-DOSY) NMR spectroscopy. Influences of different factors on the self-diffusion coefficient and the equilibrium constant were investigated. The results showed that the increase of temperature , water content, pH and ionic strength had more influence on the self-diffusion coefficient of the guest than that of the host, which could increase the equilibrium constants. The inclusion interaction was the strongest in a solution of pH 9. 0. The results of thermodynamic analysis showed that the inclusion process was spontaneous and endothermic entropy-driven process, and the main active force was the hydrophobic force.

  15. Detection of propranolol in pharmaceutical formulations by diffuse reflectance spectroscopy

    Science.gov (United States)

    Gotardo, Mara Andréia; Tognolli, João Olímpio; Pezza, Helena Redigolo; Pezza, Leonardo

    2008-04-01

    This paper describes an analytical reflectometric method that has an objective not only the industrial quality control but also to detect possible falsifications and/or adulterations of propranolol in pharmaceutical formulations. The method is based on the diffuse reflectance measurements of the colored product (III) of the spot test reaction between propranolol hydrochloride (I) and 2,6-dichloroquinone-4-chloroimide (II) using filter paper as solid support. Spot test conditions have been investigated using experimental design in order to identify and optimize the critical factors. The factors evaluated were DCQ concentration, propranolol solvent and DCQ solvent. The best reaction conditions were achieved with the addition of 30 μL of propranolol solution in ethanol 35% (v/v) and 30 μL of DCQ solution at 70 mg mL -1 in acetone, in this order. All reflectance measurements were carried out at 500 nm and the linear range was from 8.45 × 10 -4 to 8.45 × 10 -2 mol L -1 ( r = 0.998). The limit of detection was 1.01 × 10 -4 mol L -1. No interference was observed from the assessed excipients and drugs. The method was applied to determine propranolol in commercial brands of pharmaceuticals. The results obtained by the proposed method were favorably compared with those given by the British Pharmacopoeia procedure.

  16. Diffusion and spectroscopy of water and lipids in fully hydrated dimyristoylphosphatidylcholine bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J.; Martí, J., E-mail: jordi.marti@upc.edu [Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia (Spain); Calero, C. [Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia (Spain); Center for Polymer Studies, Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 (United States)

    2014-03-14

    Microscopic structure and dynamics of water and lipids in a fully hydrated dimyristoylphosphatidylcholine phospholipid lipid bilayer membrane in the liquid-crystalline phase have been analyzed with all-atom molecular dynamics simulations based on the recently parameterized CHARMM36 force field. The diffusive dynamics of the membrane lipids and of its hydration water, their reorientational motions as well as their corresponding spectral densities, related to the absorption of radiation, have been considered for the first time using the present force field. In addition, structural properties such as density and pressure profiles, a deuterium-order parameter, surface tension, and the extent of water penetration in the membrane have been analyzed. Molecular self-diffusion, reorientational motions, and spectral densities of atomic species reveal a variety of time scales playing a role in membrane dynamics. The mechanisms of lipid motion strongly depend on the time scale considered, from fast ballistic translation at the scale of picoseconds (effective diffusion coefficients of the order of 10{sup −5} cm{sup 2}/s) to diffusive flow of a few lipids forming nanodomains at the scale of hundreds of nanoseconds (diffusion coefficients of the order of 10{sup −8} cm{sup 2}/s). In the intermediate regime of sub-diffusion, collisions with nearest neighbors prevent the lipids to achieve full diffusion. Lipid reorientations along selected directions agree well with reported nuclear magnetic resonance data and indicate two different time scales, one about 1 ns and a second one in the range of 2–8 ns. We associated the two time scales of reorientational motions with angular distributions of selected vectors. Calculated spectral densities corresponding to lipid and water reveal an overall good qualitative agreement with Fourier transform infrared spectroscopy experiments. Our simulations indicate a blue-shift of the low frequency spectral bands of hydration water as a result of

  17. Diffuse reflectance spectroscopy: a new guidance tool for improvement of biopsy procedures in lung malignancies

    NARCIS (Netherlands)

    Evers, Daniel; Evers, D.J.; Nachabe, R.; Klomp, H.M.; van Sandick, J.W.; Wouters, M.W.; Lucassen, G.W.; Lucassen, Gerald; Hendriks, B.H.; Wesseling, J.; Ruers, Theo J.M.

    2012-01-01

    Background: A significant number of percutaneous intrathoracic biopsy procedures result in indeterminate cytologic or histologic diagnosis in clinical practice. Diffuse reflectance spectroscopy (DRS) is an optical technique that can distinguish different tissue types on a microscopic level. DRS may

  18. Diffuse reflectance spectroscopy: a new guidance tool for improvement of biopsy procedures in lung malignancies

    NARCIS (Netherlands)

    Evers, D.J.; Nachabe, R.; Klomp, H.M.; Sandick, van J.W.; Wouters, M.W.; Lucassen, G.W.; Hendriks, B.H.; Wesseling, J.; Ruers, T.J.M.

    2012-01-01

    Background: A significant number of percutaneous intrathoracic biopsy procedures result in indeterminate cytologic or histologic diagnosis in clinical practice. Diffuse reflectance spectroscopy (DRS) is an optical technique that can distinguish different tissue types on a microscopic level. DRS may

  19. MR diffusion imaging and 1H spectroscopy in a child with medulloblastoma: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, M. [Max-Planck-Institute of Psychiatry, Muenchen (Germany). NMR Study Group; Eidenschink, A.; Mueller-Weihrich, S. [Technical Univ. of Muenchen, (Germany). Childrens' Hospital; Auer, D.P. [Max-Planck-Institute of Psychiatry, Muenchen (Germany). NMR Study Group

    2000-01-01

    We report on a child with a metastasising medulloblastoma which was assessed by MR diffusion imaging and 1H MR spectroscopy (MRS). Reduced mean apparent diffusion coefficients and a high amount of taurine could be demonstrated. This is the first reported case of high taurine in medulloblastoma in vivo and confirms earlier in vitro findings. It is suggested that the changes on diffusion imaging, possibly reflecting the small-cell histology of the tumour and high taurine in MRS, are indicative of medulloblastoma.

  20. GAS SORPTION, DIFFUSION AND PERMEATION OF ORDERED POLYMERIC MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Yoshiharu Tsujita

    2000-01-01

    He, CO2, O2, N2, CH4, C3H8, and t-C4H10 gas permeability coefficients and diffusion coefficients ofpoly(4-methyl pentene-1) (PMP) with various degrees of crystallization were plotted against the degree of crystallization. The plot demonstrated a linear relationship. The gas permeability coefficient and diffusion coefficient of pure amorphous and pure crystalline PMPs were evaluated by a linear extrapolation to zero and 100% crystallinity, respectively. The relationship between the diffusion coefficient of crystalline parts of PMP and the kinetic diameter of penetrant gases was discussed.Syndiotactic polystyrene (SPS) could exist as δ form crystals complexed with organic solvents such as benzene, toluene,xylene, and ethylbenzene. The mesophase of SPS is prepared by annealing the δ form of crystalline complexes at a certain temperature for 1 h. The desorption of solvent during annealing almost does not result in changes of both the conformation of backbone chains and the crystal lattice. We could prepare the mesophase containing molecular cavities with the size and shape of the organic solvent molecules. The mesophase could sorb the same solvent after the manner of Langmuir sorption at low vapor pressure range while this would not be the case for solvents of different size and shape. This suggests a molecular recognition of organic solvent, and mesophase SPS might be useful for separation membrane and adsorptive material.

  1. Nonlinear Theory of Anomalous Diffusion and Application to Fluorescence Correlation Spectroscopy

    Science.gov (United States)

    Boon, Jean Pierre; Lutsko, James F.

    2015-12-01

    The nonlinear theory of anomalous diffusion is based on particle interactions giving an explicit microscopic description of diffusive processes leading to sub-, normal, or super-diffusion as a result of competitive effects between attractive and repulsive interactions. We present the explicit analytical solution to the nonlinear diffusion equation which we then use to compute the correlation function which is experimentally measured by correlation spectroscopy. The theoretical results are applicable in particular to the analysis of fluorescence correlation spectroscopy of marked molecules in biological systems. More specifically we consider the cases of fluorescently labeled lipids in the plasma membrane and of fluorescent apoferritin (a spherically shaped oligomer) in a crowded dextran solution and we find that the nonlinear correlation spectra reproduce very well the experimental data indicating sub-diffusive molecular motion.

  2. Studies of surface diffusion by second harmonic fluctuation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaolin; Goh, M.C.; Subrahmanyan, S.; Eisenthal, K.B. (Columbia Univ., New York, NY (USA))

    1990-05-03

    The authors have shown how the fluctuations in the signal from surface second harmonic generation can be utilized for the study of a heterogeneous surface such as palmitic acid (C{sub 15}H{sub 31}COOH) spread on the air/water interface, under conditions of gas-liquid coexistence. The authors report observations of time-correlated fluctuations in the SH signal, with decay constant of approximately 6 s. This is attributed to motions of the liquidlike clusters of palmitic acid. If the motion is diffusive, a diffusion constant of about 10{sup {minus}8} cm{sup 2}/s is estimated for these clusters.

  3. The role of the Fox-Wright functions in fractional sub-diffusion of distributed order

    CERN Document Server

    Mainardi, Francesco

    2007-01-01

    The fundamental solution of the fractional diffusion equation of distributed order in time (usually adopted for modelling sub-diffusion processes) is obtained based on its Mellin-Barnes integral representation. Such solution is proved to be related via a Laplace-type integral to the Fox-Wright functions. A series expansion is also provided in order to point out the distribution of time-scales related to the distribution of the fractional orders. The results of the time fractional diffusion equation of a single order are also recalled and then re-obtained from the general theory.

  4. ERETIC implemented in diffusion-ordered NMR as a diffusion reference.

    Science.gov (United States)

    Van Lokeren, Luk; Kerssebaum, Rainer; Willem, Rudolph; Denkova, Pavletta

    2008-01-01

    The ERETIC (Electronic Reference To access In vivo Concentrations) technique generates an electronic signal in the NMR spectrometer which is detected simultaneously to the sample FID during the acquisition. The implementation of the ERETIC sequence in any 2D DOSY experimental scheme enables one to generate directly into the raw 2D DOSY spectrum a reference signal with an attenuation simulated to describe a well-defined diffusion behavior. This simulated intensity attenuation can be used to evaluate the output generated by any DOSY data treatment algorithm, in a single as well as multichannel approach and provide insight into their precision, accuracy, scope and limitations. The ERETIC sequence implemented in the standard bipolar pulsed field gradient longitudinal eddy current delay (LED) sequence is illustrated on various algorithms presented previously in the literature for the analysis of the generated ERETIC-DOSY spectra of simulated model systems representing discrete and continuous diffusion profiles in mono- and bi-Gaussian diffusion regimes.

  5. A method for monitoring of oxygen saturation changes in brain tissue using diffuse reflectance spectroscopy.

    Science.gov (United States)

    Rejmstad, Peter; Johansson, Johannes D; Haj-Hosseini, Neda; Wårdell, Karin

    2017-03-01

    Continuous measurement of local brain oxygen saturation (SO2 ) can be used to monitor the status of brain trauma patients in the neurocritical care unit. Currently, micro-oxygen-electrodes are considered as the "gold standard" in measuring cerebral oxygen pressure (pO2 ), which is closely related to SO2 through the oxygen dissociation curve (ODC) of hemoglobin, but with the drawback of slow in response time. The present study suggests estimation of SO2 in brain tissue using diffuse reflectance spectroscopy (DRS) for finding an analytical relation between measured spectra and the SO2 for different blood concentrations. The P3 diffusion approximation is used to generate a set of spectra simulating brain tissue for various levels of blood concentrations in order to estimate SO2 . The algorithm is evaluated on optical phantoms mimicking white brain matter (blood volume of 0.5-2%) where pO2 and temperature is controlled and on clinical data collected during brain surgery. The suggested method is capable of estimating the blood fraction and oxygen saturation changes from the spectroscopic signal and the hemoglobin absorption profile.

  6. Characterisation of nanocarbon-based gas diffusion media by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gallo Stampino, P.; Omati, L.; Cristiani, C.; Dotelli, G. [Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica ' ' G. Natta' ' (Italy); INSTM R.U. POLIMI, Milano (Italy)

    2010-04-15

    A multi-wall carbon nanotubes (MWCNTs)-based gas diffusion medium (GDM) was prepared, where carbon black was partially substituted by carbon nanotube (CNT) in the formulation of the micro-porous layer (MPL). A rheological analysis of the ink used to coat the gas diffusion layer (GDL) was previously performed to correlate viscosities with the slurry composition. Shear thinning inks with viscosity of 0.4 (Pas{sup -1}) were obtained for a composition containing 10 wt.-% of CNT and 12 wt.-% of fluorinated polymer. Using the doctor-blade technique, a coating thickness of about 100-150 {mu}m was obtained. Moreover, electrochemical performance of a single cell assembled with the CNT-based GDM was compared with that obtained with a sample without CNTs. In order to better understand the role of CNTs, electrochemical impedance spectroscopy (EIS) of the running fuel cell (FC) was also performed. As a result, it was found that the addition of CNTs sensibly improves single cell performances. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Monitoring real time polymorphic transformation of sulfanilamide by diffuse reflectance visible spectroscopy

    Directory of Open Access Journals (Sweden)

    Tracy O. Ehiwe

    2016-06-01

    Full Text Available This study investigated the development of a novel approach to surface characterization of drug polymorphism and the extension of the capabilities of this method to perform ‘real time’ in situ measurements. This was achieved using diffuse reflectance visible (DRV spectroscopy and dye deposition, using the pH sensitive dye, thymol blue (TB. Two polymorphs, SFN-β and SFN-γ, of the drug substance sulfanilamide (SFN were examined. The interaction of adsorbed dye with polymorphs showed different behavior, and thus reported different DRV spectra. Consideration of the acid/base properties of the morphological forms of the drug molecule provided a rationalization of the mechanism of differential coloration by indicator dyes. The kinetics of the polymorphic transformation of SFN polymorphs was monitored using treatment with TB dye and DRV spectroscopy. The thermally-induced transformation fitted a first-order solid-state kinetic model (R2=0.992, giving a rate constant of 2.43×10−2 s−1.

  8. Gradient-Diffusion Methods for Simulating Decoherence by NMR Spectroscopy

    CERN Document Server

    Havel, T F; Viola, L; Cory, D G; Havel, Timothy F.; Sharf, Yehuda; Viola, Lorenza; Cory, David G.

    2001-01-01

    Theoretical techniques are developed for designing nuclear magnetic resonance (NMR) experiments to simulate a variety of adiabatic decoherence (aka T_2 relaxation) processes, using sequences of pulsed field gradients and diffusion periods. To this end an efficient Hadamard product formalism is introduced and used to derive Lindblad master equations from NMR pulse sequences for both collective and independent phase damping on any number of spins. The Kraus operator sum form is shown to be related to the Hadamard form by diagonalization, and explicit Lindblad and Kraus operators given for arbitrary correlations between two spins. Finally, gradient-diffusion methods are outlined for more complex forms of decoherence, including the three-axis collective model.

  9. Using Directional Diffusion Coefficients for Nonlinear Diffusion Acceleration of the First Order SN Equations in Near-Void Regions

    Energy Technology Data Exchange (ETDEWEB)

    Schunert, Sebastian; Hammer, Hans; Lou, Jijie; Wang, Yaqi; Ortensi, Javier; Gleicher, Frederick; Baker, Benjamin; DeHart, Mark; Martineau, Richard

    2016-11-01

    The common definition of the diffusion coeffcient as the inverse of three times the transport cross section is not compat- ible with voids. Morel introduced a non-local tensor diffusion coeffcient that remains finite in voids[1]. It can be obtained by solving an auxiliary transport problem without scattering or fission. Larsen and Trahan successfully applied this diffusion coeffcient for enhancing the accuracy of diffusion solutions of very high temperature reactor (VHTR) problems that feature large, optically thin channels in the z-direction [2]. It is demonstrated that a significant reduction of error can be achieved in particular in the optically thin region. Along the same line of thought, non-local diffusion tensors are applied modeling the TREAT reactor confirming the findings of Larsen and Trahan [3]. Previous work of the authors have introduced a flexible Nonlinear-Diffusion Acceleration (NDA) method for the first order S N equations discretized with the discontinuous finite element method (DFEM), [4], [5], [6]. This NDA method uses a scalar diffusion coeffcient in the low-order system that is obtained as the flux weighted average of the inverse transport cross section. Hence, it su?ers from very large and potentially unbounded diffusion coeffcients in the low order problem. However, it was noted that the choice of the diffusion coeffcient does not influence consistency of the method at convergence and hence the di?usion coeffcient is essentially a free parameter. The choice of the di?usion coeffcient does, however, affect the convergence behavior of the nonlinear di?usion iterations. Within this work we use Morel’s non-local di?usion coef- ficient in the aforementioned NDA formulation in lieu of the flux weighted inverse of three times the transport cross section. The goal of this paper is to demonstrate that significant en- hancement of the spectral properties of NDA can be achieved in near void regions. For testing the spectral properties of the NDA

  10. Probing density waves in fluidized granular media with diffusing-wave spectroscopy

    Science.gov (United States)

    Born, Philip; Reinhold, Steffen; Sperl, Matthias

    2016-09-01

    Density waves are characteristic for fluidized beds and affect measurements on liquidlike dynamics in fluidized granular media. Here the intensity autocorrelation function as obtainable with diffusing-wave spectroscopy is derived in the presence of density waves. The predictions by the derived form of the intensity autocorrelation function match experimental observations from a gas-fluidized bed. The model suggests separability of the contribution from density waves from the contribution by microscopic scatterer displacement to the decay of correlation and thus paves the way for characterizing microscopic particle motions using diffusing-wave spectroscopy as well as heterogeneities in fluidized granular media.

  11. Study of diffusion of indocyanine green as a photodynamic dye into skin using backscattering spectroscopy

    Science.gov (United States)

    Genina, E. A.; Bashkatov, A. N.; Tuchin, V. V.

    2014-07-01

    One of the lines of development of modern medicine is theranostics consisting in simultaneous diagnosis and laser treatment with the use of multifunctional agents such as fluorescent indocyanine green that has photodynamic and photothermal properties. Diffusion of indocyanine green dissolved in water and aqueous solutions of alcohols (glycerol, propylene glycol and ethanol) into the dermis is studied by using backscattering spectroscopy. The coefficients of the dye diffusion into the dermis are obtained for the first time by using these solvents.

  12. Study of diffusion of indocyanine green as a photodynamic dye into skin using backscattering spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Genina, E A; Bashkatov, A N; Tuchin, V V [N.G. Chernyshevsky Saratov State University, Saratov (Russian Federation)

    2014-07-31

    One of the lines of development of modern medicine is theranostics consisting in simultaneous diagnosis and laser treatment with the use of multifunctional agents such as fluorescent indocyanine green that has photodynamic and photothermal properties. Diffusion of indocyanine green dissolved in water and aqueous solutions of alcohols (glycerol, propylene glycol and ethanol) into the dermis is studied by using backscattering spectroscopy. The coefficients of the dye diffusion into the dermis are obtained for the first time by using these solvents. (laser biophotonics)

  13. Pulsed-laser Pumped Photothermal Deflection Spectroscopy for Liquid Thermal Diffusivity Measurement

    Institute of Scientific and Technical Information of China (English)

    XIAO Liantuan; LI Changyong; ZHANG Linjie; ZHAO Yanting; JIA Suotang; ZHOU Guosheng

    2000-01-01

    The pulsed-laser pumped photothermal deflection spectroscopy (PPDS) is applied to measure liquid thermal diffusivity in a modified collinear configuration. Here the pulsed beam is regarded as in the form of a Dirac delta function. The experiment setup used is described. Measurement result for the thermal diffusivity of a liquid sample(magnta/ethanol saturated solution) is reported. The measurement error is less than 3%.

  14. Characterizing tumor response to chemotherapy at various length scales using temporal diffusion spectroscopy.

    Directory of Open Access Journals (Sweden)

    Junzhong Xu

    Full Text Available Measurements of apparent diffusion coefficient (ADC using magnetic resonance imaging (MRI have been suggested as potential imaging biomarkers for monitoring tumor response to treatment. However, conventional pulsed-gradient spin echo (PGSE methods incorporate relatively long diffusion times, and are usually sensitive to changes in cell density and necrosis. Diffusion temporal spectroscopy using the oscillating gradient spin echo (OGSE sequence is capable of probing short length scales, and may detect significant intracellular microstructural changes independent of gross cell density changes following anti-cancer treatment. To test this hypothesis, SW620 xenografts were treated by barasertib (AZD1152, a selective inhibitor of Aurora B kinase which causes SW620 cancer cells to develop polyploidy and increase in size following treatment, ultimately leading to cell death through apoptosis. Following treatment, the ADC values obtained by both the PGSE and low frequency OGSE methods increased. However, the ADC values at high gradient frequency (i.e. short diffusion times were significantly lower in treated tumors, consistent with increased intracellular restrictions/hindrances. This suggests that ADC values at long diffusion times are dominated by tumor microstructure at long length scales, and may not convey unambiguous information of subcellular space. While the diffusion temporal spectroscopy provides more comprehensive means to probe tumor microstructure at various length scales. This work is the first study to probe intracellular microstructural variations due to polyploidy following treatment using diffusion MRI in vivo. It is also the first observation of post-treatment ADC changes occurring in opposite directions at short and long diffusion times. The current study suggests that temporal diffusion spectroscopy potentially provides pharmacodynamic biomarkers of tumor early response which distinguish microstructural variations following

  15. Imaging features in conventional MRI, spectroscopy and diffusion weighted images of hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS).

    Science.gov (United States)

    Bender, Benjamin; Klose, Uwe; Lindig, Tobias; Biskup, Saskia; Nägele, Thomas; Schöls, Ludger; Karle, Kathrin N

    2014-12-01

    Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is a rare autosomal dominant disease caused by mutations within the colony stimulating factor 1 receptor (CSF1R) gene. While a small number of reports on imaging findings in routine MRI exist, reported imaging findings in DWI and spectroscopy are scarce, and limited to not genetically proven case reports. We assessed MRI including DWI and MR spectroscopy in six patients with HDLS and two asymptomatic mutation carriers. A total of 13 MRIs were evaluated and a score of the white-matter lesion (WML) load was calculated. The course of MR abnormalities was followed for 6-19 months in four patients and 95 months in one carrier. MRI revealed widespread white-matter lesions of patchy or confluent pattern especially in the frontal and occipital lobe. The pyramidal tract was less affected than the surrounding tissue in all symptomatic patients on conventional T2WI. Three of four cases with DWI showed small dots of diffusion restriction within WML. Spectroscopy showed increased levels of mIns, Cho and lactate while NAA was decreased. Asymptomatic mutation carriers had, for the age of the patients, unusually pronounced unspecific WMLs. No diffusion restriction or alterations in metabolite levels could be detected in asymptomatic mutation carriers. Microbleeds were not found in any patient. Diffusion restriction seems to be a typical imaging pattern visible in patients with active disease progression in HDLS. Spectroscopic findings and the absence of microbleeds differ clearly from reported findings in CADASIL and subcortical arteriosclerotic encephalopathy. While the distribution and character of WMLs in asymptomatic cases remain unspecific they are likely to represent subclinical markers of HDLS.

  16. Hydrogen solubility and diffusion in austenitic stainless steels studied with thermal desorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yagodzinskyy, Y.; Todoshchenko, O.; Papula, S.; Haenninen, H. [Laboratory of Engineering Materials, School of Science and Technology, Aalto University, Espoo (Finland)

    2011-01-15

    Hydrogen solubility and diffusion in austenitic stainless steels, namely AISI 310, AISI 301LN and AISI 201, are studied with thermal desorption spectroscopy (TDS) after electrochemical potentiostatic hydrogen pre-charging. Temperature dependencies of hydrogen desorption for all studied steels manifest a complex main peak caused by hydrogen releasing from the steel lattice by diffusion. Depending on the steel and heating rate the peak is situated from 350 to 500 K and its shape reflects a specific of hydrogen diffusion in stainless steels, which are multicomponent alloys. Analysis of the TDS curves is based on the hydrogen diffusion model taking into account trapping of hydrogen atoms in the energetically deep interstitial positions in the steel crystal lattice. Diffusion coefficient of hydrogen and its total content after the same charging procedure are obtained from the TDS curves and compared for the studied steels. (Copyright copyright 2011 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. In vivo detection of epileptic brain tissue using static fluorescence and diffuse reflectance spectroscopy.

    Science.gov (United States)

    Yadav, Nitin; Bhatia, Sanjiv; Ragheb, John; Mehta, Rupal; Jayakar, Prasanna; Yong, William; Lin, Wei-Chiang

    2013-02-01

    Diffuse reflectance and fluorescence spectroscopy are used to detect histopathological abnormalities of an epileptic brain in a human subject study. Static diffuse reflectance and fluorescence spectra are acquired from normal and epileptic brain areas, defined by electrocorticography (ECoG), from pediatric patients undergoing epilepsy surgery. Biopsy specimens are taken from the investigated sites within an abnormal brain. Spectral analysis reveals significant differences in diffuse reflectance spectra and the ratio of fluorescence and diffuse reflectance spectra from normal and epileptic brain areas defined by ECoG and histology. Using these spectral differences, tissue classification models with accuracy above 80% are developed based on linear discriminant analysis. The differences between the diffuse reflectance spectra from the normal and epileptic brain areas observed in this study are attributed to alterations in the static hemodynamic characteristics of an epileptic brain, suggesting a unique association between the histopathological and the hemodynamic abnormalities in an epileptic brain.

  18. A high-order splitting scheme for the advection-diffusion equation of pollutants

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A high-order splitting scheme for the advection-diffusion equation of pollutants is proposed in this paper. The multidimensional advection-diffusion equation is splitted into several one-dimensional equations that are solved by the scheme. Only three spatial grid points are needed in each direction and the scheme has fourth-order spatial accuracy. Several typically pure advection and advection-diffusion problems are simulated. Numerical results show that the accuracy of the scheme is much higher than that of the classical schemes and the scheme can be efficiently solved with little programming effort.

  19. Noninvasive particle sizing using camera-based diffuse reflectance spectroscopy

    DEFF Research Database (Denmark)

    Abildgaard, Otto Højager Attermann; Frisvad, Jeppe Revall; Falster, Viggo

    2016-01-01

    , but their low spatial resolution limits their validity ranges for the coefficients. To cover a wider range of coefficients, we use camera-based spectroscopic oblique incidence reflectometry. We develop a noninvasive technique for acquisition of apparent particle size distributions based on this approach. Our......Diffuse reflectance measurements are useful for noninvasive inspection of optical properties such as reduced scattering and absorption coefficients. Spectroscopic analysis of these optical properties can be used for particle sizing. Systems based on optical fiber probes are commonly employed...... technique is validated using stable oil-in-water emulsions with a wide range of known particle size distributions. We also measure the apparent particle size distributions of complex dairy products. These results show that our tool, in contrast to those based on fiber probes, can deal with a range...

  20. Efficient high-order discontinuous Galerkin schemes with first-order hyperbolic advection-diffusion system approach

    Science.gov (United States)

    Mazaheri, Alireza; Nishikawa, Hiroaki

    2016-09-01

    We propose arbitrary high-order discontinuous Galerkin (DG) schemes that are designed based on a first-order hyperbolic advection-diffusion formulation of the target governing equations. We present, in details, the efficient construction of the proposed high-order schemes (called DG-H), and show that these schemes have the same number of global degrees-of-freedom as comparable conventional high-order DG schemes, produce the same or higher order of accuracy solutions and solution gradients, are exact for exact polynomial functions, and do not need a second-derivative diffusion operator. We demonstrate that the constructed high-order schemes give excellent quality solution and solution gradients on irregular triangular elements. We also construct a Weighted Essentially Non-Oscillatory (WENO) limiter for the proposed DG-H schemes and apply it to discontinuous problems. We also make some accuracy comparisons with conventional DG and interior penalty schemes. A relative qualitative cost analysis is also reported, which indicates that the high-order schemes produce orders of magnitude more accurate results than the low-order schemes for a given CPU time. Furthermore, we show that the proposed DG-H schemes are nearly as efficient as the DG and Interior-Penalty (IP) schemes as these schemes produce results that are relatively at the same error level for approximately a similar CPU time.

  1. Time-resolved diffusing wave spectroscopy applied to dynamic heterogeneity imaging

    CERN Document Server

    Cheikh, M; Ettori, D; Tinet, E; Avrillier, S; Tualle, J M; Cheikh, Monia; Nghiem, Ha Lien; Ettori, Dominique; Tinet, Eric; Avrillier, Sigrid; Tualle, Jean-Michel

    2006-01-01

    We report in this paper what is to our knowledge the first observation of a time-resolved diffusing wave spectroscopy signal recorded by transillumination through a thick turbid medium: the DWS signal is measured for a fixed photon transit time, which opens the possibility of improving the spatial resolution. This technique could find biomedical applications, especially in mammography.

  2. MR spectroscopy and diffusion tensor imaging of the brain in Sjogren-Larsson syndrome

    NARCIS (Netherlands)

    Sijens, P. E.; Westerlaan, H. E.; de Groot, J. C.; Boon, M.; Potze, J. H.; van Spronsen, F. J.; Lunsing, R. J.; Oudkerk, M.

    2009-01-01

    Diffusion tensor imaging (DTI) is reported for the first time in a patient with Sjogren-Larsson syndrome, an autosomal recessive neurocutaneous disorder. Magnetic resonance spectroscopy (MRS) revealed normal levels of choline, creatine and N-acetyl aspartate (NAA) and the characteristic lipid signal

  3. Diffuse reflectance spectroscopy : toward real-time quantification of steatosis in liver

    NARCIS (Netherlands)

    Evers, Daniel J.; Westerkamp, Andrie C.; Spliethoff, Jarich W.; Pully, Vishnu V.; Hompes, Daphne; Hendriks, Benno H. W.; Prevoo, Warner; van Velthuysen, Marie-Louise F.; Porte, Robert J.; Ruers, Theo J. M.

    2015-01-01

    Assessment of fatty liver grafts during orthotopic liver transplantation is a challenge due to the lack of real-time analysis options during surgery. Diffuse reflectance spectroscopy (DRS) could be a new diagnostic tool to quickly assess steatosis. Eight hundred and seventy-eight optical measurement

  4. Recent progress in diffuse reflectance spectroscopy of supported metal oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    Diffuse reflectance spectroscopy is a suitable technique for studying heterogeneous catalysts, as both d-d and charge transfer transitions of supported transition metal ions can be probed. Within the past several years, new developments have resulted in a more detailed understanding of the surface c

  5. Direct Quantification of Solute Diffusivity in Agarose and Articular Cartilage Using Correlation Spectroscopy.

    Science.gov (United States)

    Shoga, Janty S; Graham, Brian T; Wang, Liyun; Price, Christopher

    2017-06-13

    Articular cartilage is an avascular tissue; diffusive transport is critical for its homeostasis. While numerous techniques have been used to quantify diffusivity within porous, hydrated tissues and tissue engineered constructs, these techniques have suffered from issues regarding invasiveness and spatial resolution. In the present study, we implemented and compared two separate correlation spectroscopy techniques, fluorescence correlation spectroscopy (FCS) and raster image correlation spectroscopy (RICS), for the direct, and minimally-invasive quantification of fluorescent solute diffusion in agarose and articular cartilage. Specifically, we quantified the diffusional properties of fluorescein and Alexa Fluor 488-conjugated dextrans (3k and 10k) in aqueous solutions, agarose gels of varying concentration (i.e. 1, 3, 5%), and in different zones of juvenile bovine articular cartilage explants (i.e. superficial, middle, and deep). In agarose, properties of solute diffusion obtained via FCS and RICS were inversely related to molecule size, gel concentration, and applied strain. In cartilage, the diffusional properties of solutes were similarly dependent upon solute size, cartilage zone, and compressive strain; findings that agree with work utilizing other quantification techniques. In conclusion, this study established the utility of FCS and RICS as simple and minimally invasive techniques for quantifying microscale solute diffusivity within agarose constructs and articular cartilage explants.

  6. Fluorescence correlation spectroscopy diffusion laws in the presence of moving nanodomains

    Science.gov (United States)

    Šachl, Radek; Bergstrand, Jan; Widengren, Jerker; Hof, Martin

    2016-03-01

    It has been shown by means of simulations that spot variation fluorescence correlation spectroscopy (sv-FCS) can be used for the identification and, to some extent, also characterization of immobile lipid nanodomains in model as well as cellular plasma membranes. However, in these simulations, the nanodomains were assumed to be stationary, whereas they actually tend to move like the surrounding lipids. In the present study, we investigated how such domain movement influences the diffusion time/spot-size dependence observed in FCS experiments, usually referred to as ‘diffusion law’ analysis. We show that domain movement might mask the effects of the ‘anomalous’ diffusion characteristics of membrane lipids or proteins predicted for stationary domains, making it difficult to identify such moving nanodomains by sv-FCS. More specifically, our simulations indicate that (i) for domains moving up to a factor of 2.25 slower than the surrounding lipids, such impeded diffusion cannot be observed and the diffusion behaviour of the proteins or lipids is indistinguishable from that of freely diffusing molecules, i.e. nanodomains are not detected; (ii) impeded protein/lipid diffusion behaviour can be observed in experiments where the radii of the detection volume are similar in size to the domain radii, the domain diffusion is about 10 times slower than that of the lipids, and the probes show a high affinity to the domains; and (iii) presence of nanodomains can only be reliably detected by diffraction limited sv-FCS when the domains move very slowly (about 200 times slower than the lipid diffusion). As nanodomains are expected to be in the range of tens of nanometres and most probes show low affinities to such domains, sv-FCS is limited to stationary domains and/or STED-FCS. However, even for that latter technique, diffusing domains smaller than 50 nm in radius are hardly detectable by FCS diffusion time/spot-size dependencies.

  7. Non-invasive detection of periodontal disease using diffuse reflectance spectroscopy: a clinical study

    Science.gov (United States)

    Prasanth, Chandra Sekhar; Betsy, Joseph; Subhash, Narayanan; Jayanthi, Jayaraj L.; Prasanthila, Janam

    2012-03-01

    In clinical diagnostic procedures, gingival inflammation is considered as the initial stage of periodontal breakdown. This is often detected clinically by bleeding on probing as it is an objective measure of inflammation. Since conventional diagnostic procedures have several inherent drawbacks, development of novel non-invasive diagnostic techniques assumes significance. This clinical study was carried out in 15 healthy volunteers and 25 patients to demonstrate the applicability of diffuse reflectance (DR) spectroscopy for quantification and discrimination of various stages of inflammatory conditions in periodontal disease. The DR spectra of diseased lesions recorded using a point monitoring system consisting of a tungsten halogen lamp and a fiber-optic spectrometer showed oxygenated hemoglobin absorption dips at 545 and 575 nm. Mean DR spectra on normalization shows marked differences between healthy and different stages of gingival inflammation. Among the various DR intensity ratios investigated, involving oxy Hb absorption peaks, the R620/R575 ratio was found to be a good parameter of gingival inflammation. In order to screen the entire diseased area and its surroundings instantaneously, DR images were recorded with an EMCCD camera at 620 and 575 nm. We have observed that using the DR image intensity ratio R620/R575 mild inflammatory tissues could be discriminated from healthy with a sensitivity of 92% and specificity of 93%, and from moderate with a sensitivity of 83% and specificity of 96%. The sensitivity and specificity obtained between moderate and severe inflammation are 82% and 76% respectively.

  8. Using fluorescence correlation spectroscopy to study diffusion in the presence of a hierarchy of membrane domains

    Science.gov (United States)

    Kalay, Ziya

    2014-03-01

    Fluorescence correlation spectroscopy (FCS) is a commonly used experimental technique to study molecular transport, especially in biological systems. FCS is particularly useful in two-dimensional systems such as the cell membrane, where molecules approximately move in a plane over several hundreds of nanometers, and the signal to noise ratio is high. Recent observations showed that proteins and lipids in the plasma membrane (the outermost membrane of a cell) can become temporarily confined in a hierarchy of membrane domains, induced by actin filaments and dynamic clusters formed by lipids and proteins (rafts). There has been considerable interest in measuring the characteristic size and lifetime of these domains via microscopy techniques, including FCS. Even though FCS is widely applicable, interpretation of the results is often indirect, as data has to be fit to model predictions in order to extract transport coefficients. In this talk, I will present our recent theoretical and computational findings on how FCS measurements would reflect diffusion in the simultaneous presence of cytoskeleton induced membrane compartments, and raft-like domains.

  9. Evaluation of a multi-layer diffuse reflectance spectroscopy system using optical phantoms

    Science.gov (United States)

    Fredriksson, Ingemar; Saager, Rolf B.; Durkin, Anthony J.; Strömberg, Tomas

    2017-03-01

    A fiber probe-based device for assessing microcirculatory parameters, especially red blood cell (RBC) tissue fraction, their oxygen saturation and speed resolved perfusion, has been evaluated using state-of-the-art multi-layer tissue simulating phantoms. The device comprises both diffuse reflectance spectroscopy (DRS) at two source-detector separations (0.4 and 1.2 mm) and laser Doppler flowmetry (LDF) and use an inverse Monte Carlo method for identifying the parameters of a multi-layered tissue model. First, model parameters affecting scattering, absorption and geometrical parameters are fitted to measured DRS spectra, then speed parameters are fitted to LDF spectra. In this paper, the accuracy of the spectral parameters is evaluated. The measured spectral shapes at the two source-detector separations were in good agreement with forward calculated spectral shapes. In conclusion, the multi-layer skin model based on spectral features of the included chromophores, can reliably estimate the tissue fraction of RBC, its oxygen saturation and the reduced scattering coefficient spectrum of the tissue. Furthermore, it was concluded that some freedom in the relative intensity difference between the two DRS channels is necessary in order to compensate for non-modeled surface structure effects.

  10. Determination of the oxygen and nitrogen interstitial diffusion coeficient in niobium by mechanical spectroscopy

    Directory of Open Access Journals (Sweden)

    Odila Florêncio

    2006-12-01

    Full Text Available Mechanical spectroscopy measurements have been extensively used in the last decades to obtain information about many aspects of the behavior of solutes in metallic materials. Metals of body-centered cubic lattice that contain heavy interstitial elements (oxygen, nitrogen and carbon in solid solution, present anelastic relaxation peaks when submitted to cyclic tensions, due to process know stress-induced ordering. Internal friction and frequency as a function of temperature were performed between 300 K and 650 K in a polycrystalline sample of Nb, for three distinct conditions, using a torsion pendulum inverted Kê-type operating in a frequency oscillation between 1Hz and 10 Hz range, with a heating rate of 1 K/min and pressure lower than 2 x 10-5 mbar. The experimental spectra obtained for each condition of the sample, were decomposed by the successive subtraction method in elementary Debye peaks. The following metal-interstitial interactions were identified: Nb-O and Nb-N for all conditions of the sample. From the anelastic relaxation parameters obtained (relaxation strength, peak temperature, activation energy and relaxation time and lattice parameter (obtained from x ray diffraction, the determination of the oxygen and nitrogen interstitial diffusion coefficient in Nb was possible, for each condition of the sample.

  11. Feasibility of quantitative diffuse reflectance spectroscopy for targeted measurement of renal ischemia during laparoscopic partial nephrectomy

    Science.gov (United States)

    Goel, Utsav O.; Maddox, Michael M.; Elfer, Katherine N.; Dorsey, Philip J.; Wang, Mei; McCaslin, Ian Ross; Brown, J. Quincy; Lee, Benjamin R.

    2014-10-01

    Reduction of warm ischemia time during partial nephrectomy (PN) is critical to minimizing ischemic damage and improving postoperative kidney function, while maintaining tumor resection efficacy. Recently, methods for localizing the effects of warm ischemia to the region of the tumor via selective clamping of higher-order segmental artery branches have been shown to have superior outcomes compared with clamping the main renal artery. However, artery identification can prolong operative time and increase the blood loss and reduce the positive effects of selective ischemia. Quantitative diffuse reflectance spectroscopy (DRS) can provide a convenient, real-time means to aid in artery identification during laparoscopic PN. The feasibility of quantitative DRS for real-time longitudinal measurement of tissue perfusion and vascular oxygenation in laparoscopic nephrectomy was investigated in vivo in six Yorkshire swine kidneys (n=three animals). DRS allowed for rapid identification of ischemic areas after selective vessel occlusion. In addition, the rates of ischemia induction and recovery were compared for main renal artery versus tertiary segmental artery occlusion, and it was found that the tertiary segmental artery occlusion trends toward faster recovery after ischemia, which suggests a potential benefit of selective ischemia. Quantitative DRS could provide a convenient and fast tool for artery identification and evaluation of the depth, spatial extent, and duration of selective tissue ischemia in laparoscopic PN.

  12. MR diffusion imaging and MR spectroscopy of maple syrup urine disease during acute metabolic decompensation

    Energy Technology Data Exchange (ETDEWEB)

    Jan, Wajanat; Wang, Zhiyue J. [Department of Radiology, University of Pennsylvania School of Medicine, Children' s Hospital of Philadelphia, Pennsylvania (United States); Zimmerman, Robert A. [Department of Radiology, University of Pennsylvania School of Medicine, Children' s Hospital of Philadelphia, Pennsylvania (United States); Department of Radiology, Children' s Hospital of Philadelphia, 34th Street and Civic Center Boulevard, PA 19104, Philadelphia (United States); Berry, Gerard T.; Kaplan, Paige B.; Kaye, Edward M. [Department of Pediatrics, University of Pennsylvania School of Medicine, The Children' s Hospital of Philadelphia, Philadelphia, Pennsylvania (United States)

    2003-06-01

    Maple syrup urine disease (MSUD) is an inborn error of amino acid metabolism, which affects the brain tissue resulting in impairment or death if untreated. Imaging studies have shown reversible brain edema during acute metabolic decompensation. The purpose of this paper is to describe the diffusion-weighted imaging (DWI) and spectroscopy findings during metabolic decompensation and to assess the value of these findings in the prediction of patient outcome. Six patients with the diagnosis of MSUD underwent conventional MR imaging with DWI during acute presentation with metabolic decompensation. Spectroscopy with long TE was performed in four of the six patients. Follow-up examinations were performed after clinical and metabolic recovery. DWI demonstrated marked restriction of proton diffusion compatible with cytotoxic or intramyelinic sheath edema in the brainstem, basal ganglia, thalami, cerebellar and periventricular white matter and the cerebral cortex. This was accompanied by the presence of an abnormal branched-chain amino acids (BCAA) and branched-chain alpha-keto acids (BCKA) peak at 0.9 ppm as well as elevated lactate on proton spectroscopy in all four patients. The changes in all six patients were reversed with treatment without evidence of volume loss or persistent tissue damage. The presence of cytotoxic or intramyelinic edema as evidenced by restricted water diffusion on DWI, with the presence of lactate on spectroscopy, could imply imminent cell death. However, in the context of metabolic decompensation in MSUD, it appears that changes in cell osmolarity and metabolism can reverse completely after metabolic correction. (orig.)

  13. Ultrafast Third-Order Nonlinear Optical Spectroscopy of Chlorinated Hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Napoleon Thantu; Robert S. Schley

    2003-09-01

    Time-resolved Raman induced Kerr effect spectroscopy in the optical heterodyne detection configuration has been employed to investigate intermolecular, intramolecular, and reorientational dynamics in neat trichloroethylene (TCE). The reorientation time constant is directly measured from the time-resolved data, while Fourier transformation of the time-resolved data yields the intermolecular and intramolecular vibrational spectrum. Use of ultrashort, femtosecond pulses enables excitation of depolarized Raman-active transitions between 1 and 500 cm-1. The intramolecular vibrations have been identified using a previous assignment. The limitations imposed by the laser and detector noise, and other nonlinear optical processes that are manifest at high pulse intensities, on the use of this time-domain technique for performing chemical species detection are discussed using carbon tetrachloride as an example.

  14. Some aspects of fractional diffusion equations of single and distributed order

    CERN Document Server

    Mainardi, Francesco; Gorenflo, Rudolf

    2007-01-01

    The time fractional diffusion equation is obtained from the standard diffusion equation by replacing the first-order time derivative with a fractional derivative of order $\\beta \\in (0,1)$. The fundamental solution for the Cauchy problem is interpreted as a probability density of a self-similar non-Markovian stochastic process related to a phenomenon of sub-diffusion (the variance grows in time sub-linearly). A further generalization is obtained by considering a continuous or discrete distribution of fractional time derivatives of order less than one. Then the fundamental solution is still a probability density of a non-Markovian process that, however, is no longer self-similar but exhibits a corresponding distribution of time-scales.

  15. Quantifying non-ergodicity of anomalous diffusion with higher order moments.

    Science.gov (United States)

    Schwarzl, Maria; Godec, Aljaž; Metzler, Ralf

    2017-06-20

    Anomalous diffusion is being discovered in a fast growing number of systems. The exact nature of this anomalous diffusion provides important information on the physical laws governing the studied system. One of the central properties analysed for finite particle motion time series is the intrinsic variability of the apparent diffusivity, typically quantified by the ergodicity breaking parameter EB. Here we demonstrate that frequently EB is insufficient to provide a meaningful measure for the observed variability of the data. Instead, important additional information is provided by the higher order moments entering by the skewness and kurtosis. We analyse these quantities for three popular anomalous diffusion models. In particular, we find that even for the Gaussian fractional Brownian motion a significant skewness in the results of physical measurements occurs and needs to be taken into account. Interestingly, the kurtosis and skewness may also provide sensitive estimates of the anomalous diffusion exponent underlying the data. We also derive a new result for the EB parameter of fractional Brownian motion valid for the whole range of the anomalous diffusion parameter. Our results are important for the analysis of anomalous diffusion but also provide new insights into the theory of anomalous stochastic processes.

  16. Analysis of Fungal Pellets by UV-Visible Spectrum Diffuse Reflectance Spectroscopy.

    Science.gov (United States)

    Lestan, D; Podgornik, H; Perdih, A

    1993-12-01

    The application of the UV-visible spectrum diffuse reflectance spectroscopy for the determination of intracellular pH in vivo, for determination of cytochrome content, and for the noninvasive in vivo detection of the redox state of fungal mitochondrial cytochromes in filamentous fungi is introduced. The time course of the intracellular pH values, mitochondrial cytochromes, and CO-binding pigments content and the correlations between the actual redox state of cytochrome aa(3) and saturation of growth medium with oxygen in pellets of the basidiomycete Phanerochaete chrysosporium were determined. As the test microorganism, the yeast Saccharomyces cerevisiae was used. UV-visible spectrum diffuse reflectance spectroscopy proved to be a promising method for the quick and simple analysis of light-impermeable biological structures for which the classical transmittance spectrophotometric methods are difficult to implement.

  17. Physiological basis for noninvasive skin cancer diagnosis using diffuse reflectance spectroscopy

    Science.gov (United States)

    Zhang, Yao; Markey, Mia K.; Tunnell, James W.

    2017-02-01

    Diffuse reflectance spectroscopy offers a noninvasive, fast, and low-cost alternative to visual screening and biopsy for skin cancer diagnosis. We have previously acquired reflectance spectra from 137 lesions in 76 patients and determined the capability of spectral diagnosis using principal component analysis (PCA). However, it is not well elucidated why spectral analysis enables tissue classification. To provide the physiological basis, we used the Monte Carlo look-up table (MCLUT) model to extract physiological parameters from those clinical data. The MCLUT model results in the following physiological parameters: oxygen saturation, hemoglobin concentration, melanin concentration, vessel radius, and scattering parameters. Physiological parameters show that cancerous skin tissue has lower scattering and larger vessel radii, compared to normal tissue. These results demonstrate the potential of diffuse reflectance spectroscopy for detection of early precancerous changes in tissue. In the future, a diagnostic algorithm that combines these physiological parameters could be enable non-invasive diagnosis of skin cancer.

  18. Application of transcutaneous diffuse reflectance spectroscopy in the measurement of blood glucose concentration

    Institute of Scientific and Technical Information of China (English)

    Wenliang Chen(陈文亮); Rong Liu(刘蓉); Houxin Cui(崔厚欣); Kexin Xu(徐可欣); Lina Lü(吕丽娜)

    2004-01-01

    In this paper, the propagation characteristics of near-infrared (NIR) light in the palm tissue are analyzed,and the principle and feasibility of using transcutaneous diffuse reflectance spectroscopy for non-invasive blood glucose detection are presented. An optical probe suitable for measuring the diffuse reflectance spectrum of human palm and a non-invasive blood glucose detection system using NIR spectroscopy are designed. Based on this system, oral glucose tolerance tests are performed to measure the blood glucose concentrations of two young healthy volunteers. The partial least square calibration model is then constructed by all individual experimental data. The final result shows that correlation coefficients of the two experiments between the predicted blood glucose concentrations and the reference blood glucose concentrations are 0.9870 and 0.9854, respectively. The root mean square errors of prediction of full cross validation are 0.54 and 0.52 mmol/1, respectively.

  19. Orientational order parameter of two cyano nematogens by optical spectroscopy

    Science.gov (United States)

    Vinutha, N.; Pardhasaradhi, P.; Usha, M. K.; Revannasiddaiah, D.

    2016-05-01

    Refractive index and density measurements of two cyano nematogens, namely p-hexyloxybenzylidene p-aminobenzonitrile and p-octyloxybenzylidene p-aminobenzonitrile have been carried out. From these data, orientational order parameter S has been estimated using different methods. Principal polarizabilities have been calculated using the well-known Vuks isotropic and Neugebauer anisotropic models. Polarizability anisotropy has been estimated using Lippincott δ-function, molecular vibration, Haller's extrapolation and Vuks scaling methods. Using these values, the orientational order parameter S has been estimated at different temperatures in their nematic phases. The values obtained have been compared and discussed. Further, using the experimental refractive index data, the nematic crossover temperatures have also been estimated for these compounds.

  20. Spectroscopie FTIR quantitative de réflectance et transmittance diffuses

    OpenAIRE

    Moser-Boroumand, Farnaz; Kovats, Ervin S.

    2005-01-01

    Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) has been established as a good and relatively sensitive method for qualitative analysis of powders and rough surfaces. The technique is non-destructive and high quality spectra can be easily obtained without extensive sample preparation. The capacity of the method for qualitative analysis of functional groups has been demonstrated in numerous fields. The potential of DRIFTS for quantitative analysis was recognized quite earl...

  1. Magnetic resonance spectroscopy to study hepatic metabolism in diffuse liver diseases, diabetes and cancer

    Institute of Scientific and Technical Information of China (English)

    Pieter; C; Dagnelie; Susanne; Leij-Halfwerk

    2010-01-01

    This review provides an overview of the current state of the art of magnetic resonance spectroscopy (MRS) in in vivo investigations of diffuse liver disease. So far, MRS of the human liver in vivo has mainly been used as a research tool rather than a clinical tool. The liver is particularly suitable for static and dynamic metabolic studies due to its high metabolic activity. Furthermore, its relatively superfi cial position allows excellent MRS localization, while its large volume allows detection of signal...

  2. The use of photon correlation spectroscopy method for determining diffusion coefficient in brine and herring flesh

    Directory of Open Access Journals (Sweden)

    Shumanova M.V.

    2015-03-01

    Full Text Available The process fish salting has been studied by the method of photon correlation spectroscopy; the distribution of salt concentration in the solution and herring flesh with skin has been found, diffusion coefficients and salt concentrations used for creating a mathematical model of the salting technology have been worked out; the possibility of determination by this method the coefficient of dynamic viscosity of solutions and different media (minced meat etc. has been considered

  3. Fluorescence correlation spectroscopy in small cytosolic compartments depends critically on the diffusion model used.

    OpenAIRE

    Gennerich, A.; Schild, D.

    2000-01-01

    Fluorescence correlation spectroscopy (FCS) is a powerful technique for measuring low concentrations of fluorescent molecules and their diffusion constants. In the standard case, fluorescence fluctuations are measured in an open detection volume defined by the confocal optics. However, if FCS measurements are carried out in cellular processes that confine the detection volume, the standard FCS model leads to erroneous results. In this paper, we derive a modified FCS model that takes into acco...

  4. A modified diffuse reflectance infrared Fourier transform spectroscopy cell for depth profiling of ceramic fibers.

    Science.gov (United States)

    Fondeur, F; Mitchell, B S

    2000-02-15

    A modified diffused reflectance infrared Fourier transformed spectroscopy (DRIFTS) accessory was used to analyze the surface properties of alumino-silicate fibers. The modifications are simple and involve a different way of performing depth-profiling from traditional DRIFTS by removing approximately 2 mm of salt from a full cup prior to placing the sample in for depth profiling. This method proved successful in elucidating the effects of quenching alumino-silicate fibers in mineral oil versus quenching in an air stream.

  5. Analysis of Fungal Pellets by UV-Visible Spectrum Diffuse Reflectance Spectroscopy

    OpenAIRE

    Leštan, Domen; Podgornik, Helena; Perdih, Anton

    1993-01-01

    The application of the UV-visible spectrum diffuse reflectance spectroscopy for the determination of intracellular pH in vivo, for determination of cytochrome content, and for the noninvasive in vivo detection of the redox state of fungal mitochondrial cytochromes in filamentous fungi is introduced. The time course of the intracellular pH values, mitochondrial cytochromes, and CO-binding pigments content and the correlations between the actual redox state of cytochrome aa3 and saturation of g...

  6. Local translational diffusion rates of membranous Na+,K(+)-ATPase measured by saturation transfer ESR spectroscopy.

    OpenAIRE

    Esmann, M.; Marsh, D.

    1992-01-01

    Diffusion-controlled Heisenberg spin exchange between spin-labeled Na+,K(+)-ATPase [ATP phosphohydrolase (Na+/K(+)-transporting), EC 3.6.1.37] proteins has been studied by saturation transfer ESR spectroscopy in reconstituted membranes. Na+,K(+)-ATPase from the salt gland of Squalus acanthias was solubilized in a polyoxyethylene ether detergent, octa(ethylene glycol) dodecyl monoether. Part of the solubilized enzyme was covalently spin-labeled with a nitroxide derivative of indanedione and re...

  7. Cavity-enhanced ultrafast two-dimensional spectroscopy using higher order modes

    Science.gov (United States)

    Allison, Thomas K.

    2017-02-01

    We describe methods using frequency combs and optical resonators for recording two-dimensional (2D) ultrafast spectroscopy signals with high sensitivity. By coupling multiple frequency combs to higher-order modes of one or more optical cavities, background-free, cavity-enhanced 2D spectroscopy signals are naturally generated via phase cycling. As in cavity-enhanced ultrafast transient absorption spectroscopy, the signal to noise is enhanced by a factor proportional to the cavity finesse squared, so even using cavities of modest finesse, a very high sensitivity is expected, enabling ultrafast 2D spectroscopy experiments in dilute molecular beams.

  8. Cavity-enhanced ultrafast two-dimensional spectroscopy using higher-order modes

    CERN Document Server

    Allison, Thomas K

    2016-01-01

    We describe methods using frequency combs and optical resonators for recording two-dimensional (2D) ultrafast spectroscopy signals with high sensitivity. By coupling multiple frequency combs to higher-order modes of one or more optical cavities, background-free, cavity-enhanced 2D spectroscopy signals are naturally generated via phase cycling. As in cavity-enhanced ultrafast transient absorption spectroscopy (CE-TAS), the signal to noise is enhanced by a factor proportional to the cavity finesse squared, so even using cavities of modest finesse, a very high sensitivity is expected, enabling ultrafast 2D spectroscopy experiments in dilute molecular beams.

  9. Neonatal hypoglycaemic encephalopathy: diffusion-weighted imaging and proton MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, So Yeon; Goo, Hyun Woo [University of Ulsan College of Medicine, Department of Radiology, Asan Medical Center, Seoul (Korea); Lim, Keun Ho; Kim, Sang Tae [Asan Institute for Life Science, NMR Laboratory, Seoul (Korea); Kim, Ki Soo [University of Ulsan College of Medicine, Department of Neonatology, Asan Medical Center, Seoul (Korea)

    2006-02-01

    We report two infants with neonatal hypoglycaemic encephalopathy who were evaluated with diffusion-weighted imaging (DWI) and proton MR spectroscopy (MRS) as well as conventional MR. As in conventional MR, DWI and proton MRS revealed a predominance of abnormalities in the parieto-occipital lobes and underlying white matter including the splenium of the corpus callosum. In the acute phase of the disease, lesions on DWI showed restricted water diffusion and on DWI the characteristic lesions seemed to be more readily discernible than on conventional MRI. In the chronic phase, DWI demonstrated increased water diffusion in the affected areas showing atrophy on conventional MRI. Proton MRS revealed an increased lactate-lipid peak and a decreased NAA peak in the involved areas. DWI and proton MRS findings appear helpful in evaluating the extent and the presence of neuronal damage early in the course of neonatal hypoglycaemic encephalopathy. (orig.)

  10. Measuring the diffusion coefficient of ganglioside on cell membrane by fluorescence correlation spectroscopy

    Science.gov (United States)

    Dong, Shiqing; You, Minghai; Chen, Jianling; Zhou, Jie; Xie, Shusen; Yang, Hongqin

    2017-06-01

    The fluidity of proteins and lipids on cell membrane plays an important role in cell’s physiological functions. Fluorescence correlation spectroscopy (FCS) is an effective technique to detect the rapid dynamic behaviors of proteins and/or lipids in living cells. In this study, we used the rhodamine6G solution to optimize the FCS system. And, cholera toxin B subunit (CT-B) was used to label ganglioside on living Hela cell membranes. The diffusion time and coefficients of ganglioside can be obtained through fitting the autocorrelation curve based on the model of two-dimensional cell membrane. The results showed that the diffusion coefficients of ganglioside distributed within a wide range. It revealed the lateral diffusion of lipids on cell membrane was inhomogeneous, which was due to different microstructures of cytoplasmic membrane. The study provides a helpful method for further studying the dynamic characteristics of proteins and lipids molecules on living cell membrane.

  11. Z-scan fluorescence correlation spectroscopy as a tool for diffusion measurements in planar lipid membranes.

    Science.gov (United States)

    Steinberger, Tomáš; Macháň, Radek; Hof, Martin

    2014-01-01

    Studies of lateral diffusion are used for the characterization of the dynamics of biological membranes. One of the techniques that can be used for this purpose is fluorescence correlation spectroscopy (FCS), which belongs to the single-molecule techniques. Unfortunately, FCS measurements, when performed in planar lipid systems, are associated with a few sources of inaccuracy in the determination of the lateral diffusion coefficient. The main problems are related to the imperfect positioning of the laser focus relative to the plane of the sample. Another source of inaccuracy is the requirement for external calibration of the detection volume size. This protocol introduces a calibration-free method called Z-scan fluorescence correlation spectroscopy (Z-scan FCS), which is based on the determination of the diffusion time and particle number in steps along the optical (z-) axis by sequential FCS measurements. Z-scan FCS could be employed for diffusion measurements in planar membrane model systems-supported phospholipid bilayers (SPBs) and giant unilamellar vesicles (GUVs) and also in biological membranes. A result from measurements in SPBs is also presented in the protocol as a principle example of the Z-scan technique.

  12. Optical Nerve Detection by Diffuse Reflectance Spectroscopy for Feedback Controlled Oral and Maxillofacial Laser Surgery

    Directory of Open Access Journals (Sweden)

    Douplik Alexandre

    2011-02-01

    Full Text Available Abstract Background Laser surgery lacks haptic feedback, which is accompanied by the risk of iatrogenic nerve damage. It was the aim of this study to investigate diffuse reflectance spectroscopy for tissue differentiation as the base of a feedback control system to enhance nerve preservation in oral and maxillofacial laser surgery. Methods Diffuse reflectance spectra of nerve tissue, salivary gland and bone (8640 spectra of the mid-facial region of ex vivo domestic pigs were acquired in the wavelength range of 350-650 nm. Tissue differentiation was performed using principal component (PC analysis followed by linear discriminant analysis (LDA. Specificity and sensitivity were calculated using receiver operating characteristic (ROC analysis and the area under curve (AUC. Results Five PCs were found to be adequate for tissue differentiation with diffuse reflectance spectra using LDA. Nerve tissue could be differed from bone as well as from salivary gland with AUC results of greater than 88%, sensitivity of greater than 83% and specificity in excess of 78%. Conclusions Diffuse reflectance spectroscopy is an adequate technique for nerve identification in the vicinity of bone and salivary gland. The results set the basis for a feedback system to prevent iatrogenic nerve damage when performing oral and maxillofacial laser surgery.

  13. Measuring diffusion with polarization-modulation dual-focus fluorescence correlation spectroscopy.

    Science.gov (United States)

    Korlann, You; Dertinger, Thomas; Michalet, Xavier; Weiss, Shimon; Enderlein, Jörg

    2008-09-15

    We present a new technique, polarization-modulation dual-focus fluorescence correlation spectroscopy (pmFCS), based on the recently intro-duced dual-focus fluorescence correlation spectroscopy (2fFCS) to measure the absolute value of diffusion coefficients of fluorescent molecules at pico- to nanomolar concentrations. Analogous to 2fFCS, the new technique is robust against optical saturation in yielding correct values of the diffusion coefficient. This is in stark contrast to conventional FCS where optical saturation leads to an apparent decrease in the determined diffusion coefficient with increasing excitation power. However, compared to 2fFCS, the new technique is simpler to implement into a conventional confocal microscope setup and is compatible with cw-excitation, only needing as add-ons an electro-optical modulator and a differential interference contrast prism. With pmFCS, the measured diffusion coefficient (D) for Atto655 maleimide in water at 25?C is determined to be equal to (4.09 +/- 0.07) x 10(-6)cm(2)/s, in good agreement with the value of 4.04 x 10-6cm2/s as measured by 2fFCS.

  14. B-meson spectroscopy in HQET at order 1/m

    Energy Technology Data Exchange (ETDEWEB)

    Bernardoni, Fabio [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Technische Univ. Dresden (Germany). Medizinische Fakultaet ' ' Carl Gustav Carus' ' ; Blossier, Benoit [Paris XI Univ. (France). Laboratoire de Physique Theorique; Bulava, John; Garron, Nicolas [Plymouth Univ. (United Kingdom). School of Computing and Mathematics; Della Morte, Michele [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins; Univ. of Southern Denmark, Odense (Denmark). Danish IAS; Instituto de Fisica Corpuscular, Valencia (Spain); CSIC, Valencia (Spain); Fritsch, Patrick [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Univ. Autonoma de Madrid (Spain). Inst. de Fisica Teorica UAM/CSIC; Gerardin, Antoine [Paris XI Univ. (France). Laboratoire de Physique Theorique; Univ. Blaise Pascal CNRS/IN2P3, Aubiere (France). Laboratoire de Physique Corpusculaire; Heitger, Jochen [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Hippel, Georg von [Mainz Univ. (Germany). Inst. fuer Kernphysik; Simma, Hubert [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Collaboration: Alpha Collaboration

    2015-05-15

    We present a study of the B spectrum performed in the framework of Heavy Quark Effective Theory expanded to next-to-leading order in 1/m{sub b} and non-perturbative in the strong coupling. Our analyses have been performed on N{sub f}=2 lattice gauge field ensembles corresponding to three different lattice spacings and a wide range of pion masses. We obtain the B{sub s}-meson mass and hyperfine splittings of the B- and B{sub s}-mesons that are in good agreement with the experimental values and examine the mass difference m{sub B{sub s}}-m{sub B} as a further cross-check of our previous estimate of the b-quark mass. We also report on the mass splitting between the first excited state and the ground state in the B and B{sub s} systems.

  15. Modelling of the magnetic field effects in hydrodynamic codes using a second order tensorial diffusion scheme

    Energy Technology Data Exchange (ETDEWEB)

    Breil, J; Maire, P-H; Nicolai, P; Schurtz, G [CELIA, Universite Bordeaux I, CNRS, CEA, 351 cours de la Liberation, 33405 Talence (France)], E-mail: breil@celia.u-bordeaux1.fr

    2008-05-15

    In laser produced plasmas large self-generated magnetic fields have been measured. The classical formulas by Braginskii predict that magnetic fields induce a reduction of the magnitude of the heat flux and its rotation through the Righi-Leduc effect. In this paper a second order tensorial diffusion method used to correctly solve the Righi-Leduc effect in multidimensional code is presented.

  16. Effects of quenched impurities on surface diffusion, spreading, and ordering of O/W(110)

    DEFF Research Database (Denmark)

    Nikunen, P.; Vattulainen, Ilpo Tapio; Ala-Nissila, T.

    2002-01-01

    We study how quenched impurities affect the surface diffusion and ordering of strongly interacting adsorbate atoms on surfaces. To this end, we carry out Monte Carlo simulations for a lattice-gas model of O/W(110), including small concentrations of immobile impurities which block their adsorption...

  17. Order book dynamics in liquid markets: limit theorems and diffusion approximations

    OpenAIRE

    Cont, Rama; De Larrard, Adrien

    2011-01-01

    Revision 2012; We propose a model for the dynamics of a limit order book in a liquid market where buy and sell orders are submitted at high frequency. We derive a functional central limit theorem for the joint dynamics of the bid and ask queues and show that, when the frequency of order arrivals is large, the intraday dynamics of the limit order book may be approximated by a Markovian jump-diffusion process in the positive orthant, whose characteristics are explicitly described in terms of th...

  18. Non-probabilistic solutions of imprecisely defined fractional-order diffusion equations

    Science.gov (United States)

    Chakraverty, S.; Smita, Tapaswini

    2014-12-01

    The fractional diffusion equation is one of the most important partial differential equations (PDEs) to model problems in mathematical physics. These PDEs are more practical when those are combined with uncertainties. Accordingly, this paper investigates the numerical solution of a non-probabilistic viz. fuzzy fractional-order diffusion equation subjected to various external forces. A fuzzy diffusion equation having fractional order 0 fuzzy initial condition is taken into consideration. Fuzziness appearing in the initial conditions is modelled through convex normalized triangular and Gaussian fuzzy numbers. A new computational technique is proposed based on double parametric form of fuzzy numbers to handle the fuzzy fractional diffusion equation. Using the single parametric form of fuzzy numbers, the original fuzzy diffusion equation is converted first into an interval-based fuzzy differential equation. Next, this equation is transformed into crisp form by using the proposed double parametric form of fuzzy numbers. Finally, the same is solved by Adomian decomposition method (ADM) symbolically to obtain the uncertain bounds of the solution. Computed results are depicted in terms of plots. Results obtained by the proposed method are compared with the existing results in special cases.

  19. Diffuse near-infrared reflectance spectroscopy during heatstroke in a mouse model: pilot study

    Science.gov (United States)

    Abookasis, David; Zafrir, Elad; Nesher, Elimelech; Pinhasov, Albert; Sternklar, Shmuel; Mathews, Marlon S.

    2012-10-01

    Heatstroke, a form of hyperthermia, is a life-threatening condition characterized by an elevated core body temperature that rises above 40°C (104°F) and central nervous system dysfunction that results in delirium, convulsions, or coma. Without emergency treatment, the victim lapses into a coma and death soon follows. The study presented was conducted with a diffuse reflectance spectroscopy (DRS) setup to assess the effects of brain dysfunction that occurred during heatstroke in mice model (n=6). It was hypothesized that DRS can be utilized in small animal studies to monitor change in internal brain tissue temperature during heatstroke injury since it induces a sequence of pathologic changes that change the tissue composition and structure. Heatstroke was induced by exposure of the mice body under general anesthesia, to a high ambient temperature. A type of DRS in which the brain tissue was illuminated through the intact scalp with a broadband light source and diffuse reflected spectra was employed, taking in the spectral region between 650 and 1000 nm and acquired at an angle of 90 deg at a position on the scalp ˜12 mm from the illumination site. The temperature at the onset of the experiment was ˜34°C (rectal temperature) with increasing intervals of 1°C until mouse death. The increase in temperature caused optical scattering signal changes consistent with a structural alteration of brain tissue, ultimately resulting in death. We have found that the peak absorbance intensity and its second derivative at specific wavelengths correlate well with temperature with an exponential dependence. Based on these findings, in order to estimate the influence of temperature on the internal brain tissue a reflectance-temperature index was established and was seen to correlate as well with measured temperature. Overall, results indicate variations in neural tissue properties during heatstroke and the feasibility to monitor and assess internal temperature variations using

  20. Intracranial yolk sac tumor in an adult patient: MRI, diffusion-weighted imaging and 1H MR spectroscopy features

    Directory of Open Access Journals (Sweden)

    Mačvanski Marija

    2012-01-01

    Full Text Available Introduction. Yolk sac tumors represent only 5%-7% of intracranial germ cell tumors, which comprise about 1% of all primary brain tumors in adults. Literature data about nonspecific imaging characteristics of these tumors are scant. We presented magnetic resonance imaging findings with diffusion-weighted imaging and proton magnetic resonance spectroscopy of this rare type of tumor in an adult patient. Case report. A 55-year-old man with progressive left side weakness, headache, dizziness and ataxia, underwent preoperative magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy. After surgical resection and histological analysis, the final diagnosis of yolk sac tumor was established. Retrospective imaging analysis were performed in order to determine imaging and biochemical parameters that could be useful in the diagnostic evaluation of this tumor type. Conclusion. Though the imaging features of yolk sac tumor are not specific, morphoanatomical and metabolic imaging could offer the information that provides new insights into this tumor that may facilitate further therapeutic decision process and potentially provides better information regarding the disease prognosis.

  1. Study of diffusion in polymer solutions and networks by fluorescence correlation spectroscopy

    Science.gov (United States)

    Chehreghanianzabi, Yasaman

    Diffusion in polymer solutions and networks is a topic of vast importance in many fields related to medical devices, tissue engineering, and drug delivery. Understanding diffusion in such environments is also essential for describing molecular transport through biological systems such as cells and tissues. Fluorescence correlation spectroscopy (FCS) is single molecule spectroscopic technique that measures the fluctuations of fluorescent probes in a defined confocal volume and correlates them in time to give information on diffusion times, concentrations, and interactions as well as indirectly, on macromolecular structure or conformation. In the first project we used diffusivity data obtained by FCS to develop a novel homogenization theory model to accurately predict solute diffusivity in polymer solutions. We focused on a setting where diffusivity was hindered by obstruction only. By choosing experimental conditions that satisfied the model assumptions, we were able to validate the homogenization theory model. While testing diffusivity in various polymer solutions, we also observed an unexpected phenomenon--a dramatic decrease in diffusivity of small fluorophores in dilute solutions of polyethylene glycol (PEG), which led to the second project. Here, we determined that the rapid drop was due to a complexation between the PEG and the fluorophore. We also determined that this complexation was highly specific and could be attributed to hydrogel bonding between the ether oxygen of PEG and the carboxylic hydrogen of the fluorophore. We then transitioned to a more complex hydrogel network environment, namely fluorophore diffusivity in various alginate hydrogels--varied by concentration and modifications with a cell adhesive ligand. Importantly, we were able to determine that while the fluorophore diffusivity was hindered due to electrostatic interactions, it was the same irrespective of the alginate concentration or modifications. The last part of this thesis was focused

  2. Instability and pattern formation in reaction-diffusion systems: a higher order analysis.

    Science.gov (United States)

    Riaz, Syed Shahed; Sharma, Rahul; Bhattacharyya, S P; Ray, D S

    2007-08-14

    We analyze the condition for instability and pattern formation in reaction-diffusion systems beyond the usual linear regime. The approach is based on taking into account perturbations of higher orders. Our analysis reveals that nonlinearity present in the system can be instrumental in determining the stability of a system, even to the extent of destabilizing one in a linearly stable parameter regime. The analysis is also successful to account for the observed effect of additive noise in modifying the instability threshold of a system. The analytical study is corroborated by numerical simulation in a standard reaction-diffusion system.

  3. Differentiating brown and white adipose tissues by high-resolution diffusion NMR spectroscopy.

    Science.gov (United States)

    Verma, Sanjay Kumar; Nagashima, Kaz; Yaligar, Jadegoud; Michael, Navin; Lee, Swee Shean; Xianfeng, Tian; Gopalan, Venkatesh; Sadananthan, Suresh Anand; Anantharaj, Rengaraj; Velan, S Sendhil

    2017-01-01

    There are two types of fat tissues, white adipose tissue (WAT) and brown adipose tissue (BAT), which essentially perform opposite functions in whole body energy metabolism. There is a large interest in identifying novel biophysical properties of WAT and BAT by a quantitative and easy-to-run technique. In this work, we used high-resolution pulsed field gradient diffusion NMR spectroscopy to study the apparent diffusion coefficient (ADC) of fat molecules in rat BAT and WAT samples. The ADC of fat in BAT and WAT from rats fed with a chow diet was compared with that of rats fed with a high-fat diet to monitor how the diffusion properties change due to obesity-associated parameters such as lipid droplet size, fatty acid chain length, and saturation. Feeding a high-fat diet resulted in increased saturation, increased chain lengths, and reduced ADC of fat in WAT. The ADC of fat was lower in BAT relative to WAT in rats fed both chow and high-fat diets. Diffusion of fat was restricted in BAT due to the presence of small multilocular lipid droplets. Our findings indicate that in vivo diffusion might be a potential way for better delineation of BAT and WAT in both lean and obese states.

  4. Local structures in ionic liquids probed and characterized by microscopic thermal diffusion monitored with picosecond time-resolved Raman spectroscopy.

    Science.gov (United States)

    Yoshida, Kyousuke; Iwata, Koichi; Nishiyama, Yoshio; Kimura, Yoshifumi; Hamaguchi, Hiro-o

    2012-03-14

    Vibrational cooling rate of the first excited singlet (S(1)) state of trans-stilbene and bulk thermal diffusivity are measured for seven room temperature ionic liquids, C(2)mimTf(2)N, C(4)mimTf(2)N, C(4)mimPF(6), C(5)mimTf(2)N, C(6)mimTf(2)N, C(8)mimTf(2)N, and bmpyTf(2)N. Vibrational cooling rate measured with picosecond time-resolved Raman spectroscopy reflects solute-solvent and solvent-solvent energy transfer in a microscopic solvent environment. Thermal diffusivity measured with the transient grating method indicates macroscopic heat conduction capability. Vibrational cooling rate of S(1) trans-stilbene is known to have a good correlation with bulk thermal diffusivity in ordinary molecular liquids. In the seven ionic liquids studied, however, vibrational cooling rate shows no correlation with thermal diffusivity; the observed rates are similar (0.082 to 0.12 ps(-1) in the seven ionic liquids and 0.08 to 0.14 ps(-1) in molecular liquids) despite large differences in thermal diffusivity (5.4-7.5 × 10(-8) m(2) s(-1) in ionic liquids and 8.0-10 × 10(-8) m(2) s(-1) in molecular liquids). This finding is consistent with our working hypothesis that there are local structures characteristically formed in ionic liquids. Vibrational cooling rate is determined by energy transfer among solvent ions in a local structure, while macroscopic thermal diffusion is controlled by heat transfer over boundaries of local structures. By using "local" thermal diffusivity, we are able to simulate the vibrational cooling kinetics observed in ionic liquids with a model assuming thermal diffusion in continuous media. The lower limit of the size of local structure is estimated with vibrational cooling process observed with and without the excess energy. A quantitative discussion with a numerical simulation shows that the diameter of local structure is larger than 10 nm. If we combine this lower limit, 10 nm, with the upper limit, 100 nm, which is estimated from the transparency (no light

  5. MR imaging of glioblastoma in children: usefulness of diffusion/perfusion-weighted MRI and MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yun-Woo; Yoon, Hye-Kyung; Roh, Hong Gee; Cho, Jae Min [Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Kangnam-gu, Seoul 135-710 (Korea); Shin, Hyung-Jin [Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Kangnam-gu, Seoul 135-710 (Korea)

    2003-12-01

    Glioblastoma is relatively uncommon in childhood and maybe difficult to differentiate from other brain tumors such as primitive neuroectodermal tumor, ependymoma, or benign astrocytoma. To describe the characteristic MR features in children with glioblastoma and to evaluate the usefulness of diffusion and perfusion MR imaging and MR spectroscopy in pediatric glioblastoma. MR imaging in 11 children (12 tumors) with biopsy-proven glioblastoma was reviewed retrospectively. In one patient, there was a recurrent glioblastoma. We reviewed CT and MRI imaging for tumor location, density/signal intensity, and enhancement pattern. Routine MR imaging was performed with a 1.5-T scanner. In six patients, diffusion-weighted MR images (DWIs) were obtained with a single-shot spin echo EPI technique with two gradient steps, and apparent diffusion coefficients (ADCs) were calculated. Using the gradient EPI technique, perfusion-weighted MR images (PWIs) were obtained in four patients from the data of dynamic MR images. The maximum relative cerebral blood volume (rCBV) ratio was calculated between the tumor and contralateral white matter in two cases. In three patients, proton MR spectroscopy was performed using a single voxel technique with either STEAM or PRESS sequences. The locations of the tumor were the thalamus and basal ganglia (n=8), deep white matter (n=3), and brain stem (n=1). Intratumoral hemorrhage was seen in four tumors. The tumors showed high-signal intensity or DWIs, having a wide range of ADC values of 0.53-1.30 (mean {+-}SD=1.011{+-}0.29). The maximum rCBV ratios of glioblastoma were 10.2 and 8.5 in two cases. MR spectroscopy showed decreased N-acetylaspartate (NAA) and increased choline in three cases. The MR findings of glioblastoma in children were: a diffusely infiltrative mass with hemorrhage involving the deep cerebral white matter, thalami, and basal ganglia. Diffusion/perfusion MR imaging and MR spectroscopy are very helpful in diagnosing glioblastoma

  6. The research on noninvasive detection of skin cholesterol by diffuse reflectance spectroscopy

    Science.gov (United States)

    Hou, Huayi; Han, Yongsheng; Dong, Meili; Zhang, Yuanzhi; Zhu, Ling; Wang, Yikun; Liu, Yong

    2017-01-01

    Skin cholesterol is a novel biomarker to assess the risk of atherosclerotic diseases. To detect skin cholesterol noninvasively and rapidly, a system was designed based on the diffuse reflectance spectroscopy. The feasibility of this system was validated through detecting cholesterol of pig skin samples, and skin cholesterol in vivo of subjects. The experimental results showed that, diffuse reflectance absorbance integrated intensity S measured the concentration of cholesterol in the pig skin samples quantitatively. After adjusting for age, gender and other factors, it showed a significant positive correlation between S of subjects and the total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) which were the main risk factors for atherosclerotic diseases with the correlation coefficients 0.860(P <0.01) and 0.787(P <0.01). The study has shown that the diffuse reflectance spectroscopy provides a noninvasive and convenient method for the detection of skin cholesterol, and the noninvasive detection of skin cholesterol in vivo will contribute to the early detection of atherosclerotic diseases.

  7. Computational Solutions of Distributed Order Reaction-Diffusion Systems Associated with Riemann-Liouville Derivatives

    Directory of Open Access Journals (Sweden)

    Ram K. Saxena

    2015-04-01

    Full Text Available This article is in continuation of the authors research attempts to derive computational solutions of an unified reaction-diffusion equation of distributed order associated with Caputo derivatives as the time-derivative and Riesz-Feller derivative as space derivative. This article presents computational solutions of distributed order fractional reaction-diffusion equations associated with Riemann-Liouville derivatives of fractional orders as the time-derivatives and Riesz-Feller fractional derivatives as the space derivatives. The method followed in deriving the solution is that of joint Laplace and Fourier transforms. The solution is derived in a closed and computational form in terms of the familiar Mittag-Leffler function. It provides an elegant extension of results available in the literature. The results obtained are presented in the form of two theorems. Some results associated specifically with fractional Riesz derivatives are also derived as special cases of the most general result. It will be seen that in case of distributed order fractional reaction-diffusion, the solution comes in a compact and closed form in terms of a generalization of the Kampé de Fériet hypergeometric series in two variables. The convergence of the double series occurring in the solution is also given.

  8. Quantifying the cerebral metabolic rate of oxygen by combining diffuse correlation spectroscopy and time-resolved near-infrared spectroscopy.

    Science.gov (United States)

    Verdecchia, Kyle; Diop, Mamadou; Lee, Ting-Yim; St Lawrence, Keith

    2013-02-01

    Preterm infants are highly susceptible to ischemic brain injury; consequently, continuous bedside monitoring to detect ischemia before irreversible damage occurs would improve patient outcome. In addition to monitoring cerebral blood flow (CBF), assessing the cerebral metabolic rate of oxygen (CMRO2) would be beneficial considering that metabolic thresholds can be used to evaluate tissue viability. The purpose of this study was to demonstrate that changes in absolute CMRO2 could be measured by combining diffuse correlation spectroscopy (DCS) with time-resolved near-infrared spectroscopy (TR-NIRS). Absolute CBF was determined using bolus-tracking TR-NIRS to calibrate the DCS measurements. Cerebral venous blood oxygenation (SvO2) was determined by multiwavelength TR-NIRS measurements, the accuracy of which was assessed by directly measuring the oxygenation of sagittal sinus blood. In eight newborn piglets, CMRO2 was manipulated by varying the anesthetics and by injecting sodium cyanide. No significant differences were found between the two sets of SvO2 measurements obtained by TR-NIRS or sagittal sinus blood samples and the corresponding CMRO2 measurements. Bland-Altman analysis showed a mean CMRO2 difference of 0.0268 ± 0.8340 mLO2/100 g/min between the two techniques over a range from 0.3 to 4 mL O2/100 g/min.

  9. Numerical Solution of Advection-Diffusion Equation Using a Sixth-Order Compact Finite Difference Method

    Directory of Open Access Journals (Sweden)

    Gurhan Gurarslan

    2013-01-01

    Full Text Available This study aims to produce numerical solutions of one-dimensional advection-diffusion equation using a sixth-order compact difference scheme in space and a fourth-order Runge-Kutta scheme in time. The suggested scheme here has been seen to be very accurate and a relatively flexible solution approach in solving the contaminant transport equation for Pe≤5. For the solution of the present equation, the combined technique has been used instead of conventional solution techniques. The accuracy and validity of the numerical model are verified through the presented results and the literature. The computed results showed that the use of the current method in the simulation is very applicable for the solution of the advection-diffusion equation. The present technique is seen to be a very reliable alternative to existing techniques for these kinds of applications.

  10. [Detection of erucic acid and glucosinolate in intact rapeseed by near-infrared diffuse reflectance spectroscopy].

    Science.gov (United States)

    Riu, Yu-kui; Huang, Kun-lun; Wang, Wei-min; Guo, Jing; Jin, Yin-hua; Luo, Yun-bo

    2006-12-01

    With the rapid development of transgenic food, more and more transgenic food has been pouring into the market, raising great concern about transgenic food' s edible safety. To analyze the content of erucic acid and glucosinolate in transgenic rapeseed and its parents, all the seeds were scanned intact by continuous wave of near infrared diffuse reflectance spectrometry ranging from 12 000 to 4 000 cm(-1) with a resolution of 4 cm(-1) and 64 times of scanning. Bruker OPUS software package was applied for quantification, while the results were compared with the standard methods. The results showed that the method of NIRS was very precise, which proved that infrared diffuse reflectance spectroscopy can be applied to detect the toxins in transgenic food. On the other hand, the results also showed that the content of erucic acid in transgenic rapeseeds is 0. 5-1. 0 times

  11. Megalencephalic leukoencephalopathy with subcortical cysts in an adult: quantitative proton MR spectroscopy and diffusion tensor MRI

    Energy Technology Data Exchange (ETDEWEB)

    Brockmann, K.; Hanefeld, F. [Dept. of Paediatrics and Neuropaediatrics, Children' s Hospital, Georg-August-Univ., Goettingen (Germany); Finsterbusch, J.; Frahm, J. [Biomedizinische NMR Forschungs GmbH am Max-Planck-Inst. fuer biophysikalische Chemie, Goettingen (Germany); Terwey, B. [Inst. fuer Magnet-Resonanz-Diagnostik, Zentralkrankenhaus, Bremen (Germany)

    2003-03-01

    A 37-year-old macrocephalic woman was investigated for increasing gait disturbance due to longstanding spasticity and ataxia. MRI showed widespread bilateral increase in signal from cerebral white matter on T2-weighted images. Numerous subcortical cysts were visible in anterior-temporal and parietal regions. These clinical and neuroradiological features are those of megalencephalic leukoencephalopathy with subcortical cysts (MLC), a recently delineated white-matter disease with onset in childhood. Quantitative localised proton MR spectroscopy of white matter revealed marked reduction of N-acetylaspartate, creatine, and choline with normal values for myoinositol, consistent with axonal loss and astrocytic proliferation. Diffusion tensor imaging showed an increased apparent diffusion coefficient and reduced anisotropy in affected white matter pointing to reduced cell density with an increased extracellular space. These findings are in line with histological changes alterations known to occur in MLC. (orig.)

  12. Serial proton MR spectroscopy and diffusion tensor imaging in infantile Balo's concentric sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Dreha-Kulaczewski, Steffi F.; Gaertner, Jutta [Georg August University, Department of Pediatrics and Pediatric Neurology, Goettingen (Germany); Helms, Gunther; Dechent, Peter [Georg August University, MR-Research in Neurology and Psychiatry, Goettingen (Germany); Hofer, Sabine [Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut fuer Biophysikalische Chemie, Goettingen (Germany)]|[Bernstein Center for Computational Neuroscience, Goettingen (Germany); Frahm, Jens [Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut fuer Biophysikalische Chemie, Goettingen (Germany)

    2009-02-15

    Proton magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) yield different parameters for characterizing the evolution of a demyelinating white matter disease. The purpose was to elucidate biochemical and microstructural changes in Balo's concentric sclerosis lesions and to correlate the findings with the clinical course. Localized short-echo time MRS and DTI were performed over 6 years in a left occipital lesion of a female patient (age at onset 13.8 years) with Balo's concentric sclerosis. A right homonym hemianopsia persisted. Metabolite patterns were in line with initial active demyelination followed by gliosis and partial recovery of neuroaxonal metabolites. Fractional anisotropy and mean diffusivity of tissue water remained severely altered. Fiber tracking confirmed a disruption in the geniculo-calcarine tract as well as involvement of the corpus callosum. MRS and DTI depict complementary parameters, but DTI seems to correlate better with clinical symptoms. (orig.)

  13. Phospholipid diffusion coefficients of cushioned model membranes determined via z-scan fluorescence correlation spectroscopy.

    Science.gov (United States)

    Sterling, Sarah M; Allgeyer, Edward S; Fick, Jörg; Prudovsky, Igor; Mason, Michael D; Neivandt, David J

    2013-06-25

    Model cellular membranes enable the study of biological processes in a controlled environment and reduce the traditional challenges associated with live or fixed cell studies. However, model membrane systems based on the air/water or oil/solution interface do not allow for incorporation of transmembrane proteins or for the study of protein transport mechanisms. Conversely, a phospholipid bilayer deposited via the Langmuir-Blodgett/Langmuir-Schaefer method on a hydrogel layer is potentially an effective mimic of the cross section of a biological membrane and facilitates both protein incorporation and transport studies. Prior to application, however, such membranes must be fully characterized, particularly with respect to the phospholipid bilayer phase transition temperature. Here we present a detailed characterization of the phase transition temperature of the inner and outer leaflets of a chitosan supported model membrane system. Specifically, the lateral diffusion coefficient of each individual leaflet has been determined as a function of temperature. Measurements were performed utilizing z-scan fluorescence correlation spectroscopy (FCS), a technique that yields calibration-free diffusion information. Analysis via the method of Wawrezinieck and co-workers revealed that phospholipid diffusion changes from raftlike to free diffusion as the temperature is increased-an insight into the dynamic behavior of hydrogel supported membranes not previously reported.

  14. Interaction of mineral surfaces with simple organic molecules by diffuse reflectance IR spectroscopy (DRIFT)

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Joan E.; Kelley, Michael J.

    2008-06-01

    Diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) was used to characterize multi-layers of lysine, glutamic acid and salicylic acid on -alumina and kaolinite surfaces. The results agreed well with those previously obtained by ATR-IR in aqueous media where available, indicating that DRIFT may be regarded as effectively an in-situ spectroscopy for these materials. In the case of salicylic acid adsorption onto γ-alumina, DRIFTS was used to identify monolayer coverage and to detect molecules down to coverage of 3% of a monolayer. The spectroscopic results as to coverage were confirmed by analysis of the solutions used for treatment. The spectra obtained allowed identification of changes in the bonding environment with increasing surface coverage. DRIFTS, offers several advantages in terms of materials, experimental technique and data treatment, motivating further investigations.

  15. Proton Diffusion Coefficient in Electrospun Hybrid Membranes by Electrochemical Impedance Spectroscopy.

    Science.gov (United States)

    Dos Santos, Leslie; Laberty-Robert, Christel; Maréchal, Manuel; Perrot, Hubert; Sel, Ozlem

    2015-09-15

    Electrochemical Impedance Spectroscopy (EIS) was, for the first time, used to estimate the global transverse proton diffusion coefficient, D(H+)(EHM), in electrospun hybrid conducting membranes (EHMs). In contrast to conventional impedance spectroscopy, EIS measurements were performed at room temperature with a liquid interface. In this configuration, the measure of the bulk proton transport is influenced by the kinetics of the transfer of proton at the solid/liquid interface. We demonstrated that the use of additives in the process of the membrane impacts the organization of the hydrophilic domains and also the proton transport. The D(H+)(EHM) is close to 1.10(-7) cm(2) s(-1) (± 0.1.10(-7) cm(2) s(-1)) for the EHMs without additive, whereas it is 4.10(-6) cm(2) s(-1) (± 0.4.10(-6) cm(2) s(-1)) for EHMs with additives.

  16. Recent Developments in Fluorescence Correlation Spectroscopy for Diffusion Measurements in Planar Lipid Membranes

    Directory of Open Access Journals (Sweden)

    Martin Hof

    2010-01-01

    Full Text Available Fluorescence correlation spectroscopy (FCS is a single molecule technique used mainly for determination of mobility and local concentration of molecules. This review describes the specific problems of FCS in planar systems and reviews the state of the art experimental approaches such as 2-focus, Z-scan or scanning FCS, which overcome most of the artefacts and limitations of standard FCS. We focus on diffusion measurements of lipids and proteins in planar lipid membranes and review the contributions of FCS to elucidating membrane dynamics and the factors influencing it, such as membrane composition, ionic strength, presence of membrane proteins or frictional coupling with solid support.

  17. Temperature-dependent gelation process in colloidal dispersions by diffusing wave spectroscopy.

    Science.gov (United States)

    Liu, Jiaxue; Boyko, Volodymyr; Yi, Zhiyong; Men, Yongfeng

    2013-11-19

    Temperature-dependent microrheology of a concentrated charge-stabilized poly(methyl methacrylate) colloidal dispersion with different salt concentrations was investigated by diffusing wave spectroscopy in backscattering mode. The critical temperature where the system undergoes aggregation and gelation depends upon the particle volume fraction or salt concentration. The viscoelastic properties of the systems have been discussed using Maxwell and Kelvin-Voigt models. Temperature-dependent crossover (G' = G″) frequency has been used to calculate activation energies representing a critical energy of interaction of gel formation.

  18. Identifying space-dependent coefficients and the order of fractionality in fractional advection diffusion equation

    CERN Document Server

    Maryshev, Boris; Latrille, Christelle; Néel, Marie-Christine

    2016-01-01

    Tracer tests in natural porous media sometimes show abnormalities that suggest considering a fractional variant of the Advection Diffusion Equation supplemented by a time derivative of non-integer order. We are describing an inverse method for this equation: it finds the order of the fractional derivative and the coefficients that achieve minimum discrepancy between solution and tracer data. Using an adjoint equation divides the computational effort by an amount proportional to the number of freedom degrees, which becomes large when some coefficients depend on space. Method accuracy is checked on synthetical data, and applicability to actual tracer test is demonstrated.

  19. In vivo water state measurements in breast cancer using broadband diffuse optical spectroscopy

    Science.gov (United States)

    Chung, S. H.; Cerussi, A. E.; Klifa, C.; Baek, H. M.; Birgul, O.; Gulsen, G.; Merritt, S. I.; Hsiang, D.; Tromberg, B. J.

    2008-12-01

    Structural changes in water molecules are related to physiological, anatomical and pathological properties of tissues. Near infrared (NIR) optical absorption methods are sensitive to water; however, detailed characterization of water in thick tissues is difficult to achieve because subtle spectral shifts can be obscured by multiple light scattering. In the NIR, a water absorption peak is observed around 975 nm. The precise NIR peak's shape and position are highly sensitive to water molecular disposition. We introduce a bound water index (BWI) that quantifies shifts observed in tissue water absorption spectra measured by broadband diffuse optical spectroscopy (DOS). DOS quantitatively measures light absorption and scattering spectra and therefore reveals bound water spectral shifts. BWI as a water state index was validated by comparing broadband DOS to magnetic resonance spectroscopy, diffusion-weighted MRI and conductivity in bound water tissue phantoms. Non-invasive DOS measurements of malignant and normal breast tissues performed in 18 subjects showed a significantly higher fraction of free water in malignant tissues (p breast cancer tissues inversely correlated with Nottingham-Bloom-Richardson histopathology scores. These results highlight broadband DOS sensitivity to molecular disposition of water and demonstrate the potential of BWI as a non-invasive in vivo index that correlates with tissue pathology.

  20. Characterizing the moisture content of tea with diffuse reflectance spectroscopy using wavelet transform and multivariate analysis.

    Science.gov (United States)

    Li, Xiaoli; Xie, Chuanqi; He, Yong; Qiu, Zhengjun; Zhang, Yanchao

    2012-01-01

    Effects of the moisture content (MC) of tea on diffuse reflectance spectroscopy were investigated by integrated wavelet transform and multivariate analysis. A total of 738 representative samples, including fresh tea leaves, manufactured tea and partially processed tea were collected for spectral measurement in the 325-1,075 nm range with a field portable spectroradiometer. Then wavelet transform (WT) and multivariate analysis were adopted for quantitative determination of the relationship between MC and spectral data. Three feature extraction methods including WT, principal component analysis (PCA) and kernel principal component analysis (KPCA) were used to explore the internal structure of spectral data. Comparison of those three methods indicated that the variables generated by WT could efficiently discover structural information of spectral data. Calibration involving seeking the relationship between MC and spectral data was executed by using regression analysis, including partial least squares regression, multiple linear regression and least square support vector machine. Results showed that there was a significant correlation between MC and spectral data (r = 0.991, RMSEP = 0.034). Moreover, the effective wavelengths for MC measurement were detected at range of 888-1,007 nm by wavelet transform. The results indicated that the diffuse reflectance spectroscopy of tea is highly correlated with MC.

  1. Characterizing the Moisture Content of Tea with Diffuse Reflectance Spectroscopy Using Wavelet Transform and Multivariate Analysis

    Directory of Open Access Journals (Sweden)

    Chuanqi Xie

    2012-07-01

    Full Text Available Effects of the moisture content (MC of tea on diffuse reflectance spectroscopy were investigated by integrated wavelet transform and multivariate analysis. A total of 738 representative samples, including fresh tea leaves, manufactured tea and partially processed tea were collected for spectral measurement in the 325–1,075 nm range with a field portable spectroradiometer. Then wavelet transform (WT and multivariate analysis were adopted for quantitative determination of the relationship between MC and spectral data. Three feature extraction methods including WT, principal component analysis (PCA and kernel principal component analysis (KPCA were used to explore the internal structure of spectral data. Comparison of those three methods indicated that the variables generated by WT could efficiently discover structural information of spectral data. Calibration involving seeking the relationship between MC and spectral data was executed by using regression analysis, including partial least squares regression, multiple linear regression and least square support vector machine. Results showed that there was a significant correlation between MC and spectral data (r = 0.991, RMSEP = 0.034. Moreover, the effective wavelengths for MC measurement were detected at range of 888–1,007 nm by wavelet transform. The results indicated that the diffuse reflectance spectroscopy of tea is highly correlated with MC.

  2. [Detection of benzoyl peroxide in wheat flour by NIR diffuse reflectance spectroscopy technique].

    Science.gov (United States)

    Zhang, Zhi-yong; Li, Gang; Liu, Hai-xue; Lin, Ling; Zhang, Bao-ju; Wu, Xiao-rong

    2011-12-01

    Adding benzoyl peroxide (BPO) into wheat flour was prohibited by the relevant government departments since May 1, 2011. And it is of great importance to detect BPO additive amount in wheat flour quickly and accurately. Part of BPO which was added into wheat flour will be deoxidized into benzoic acid, and this make it complex to detect the original BPO additive amount. The objective of the present research is to investigate the potential of NIR diffuse reflectance spectroscopy as a way for measurement of BPO original adding amount in wheat flour. A total of 133 wheat flour samples were prepared by adding different content of BPO into pure wheat flour. Spectra data were obtained by NIR spectrometer and then denoised by wavelet transform. Ninety seven samples were taken as calibration set and other 36 samples as prediction set. Partial least squares regression (PLSR) was applied to establish the calibration model between BPO original adding contents and the spectra data. The determination coefficient of model for the calibration set is 0.8901, and root mean squared error of calibration (RMSEC) is 40.85 mg x kg(-1). The determination coefficient for the prediction set is 0.8865, and root mean squared error of prediction (RMSEP) is 44.69 mg x kg(-1). The result indicates that it is feasible to detect the BPO adding contents in wheat flour by NIR diffuse reflectance spectroscopy technique and this technique has the potential to measure some other additives in food.

  3. Diffuse reflectance spectroscopy for monitoring diabetic foot ulcer - A pilot study

    Science.gov (United States)

    Anand, Suresh; Sujatha, N.; Narayanamurthy, V. B.; Seshadri, V.; Poddar, Richa

    2014-02-01

    Foot ulceration due to diabetes mellitus is a major problem affecting 12-25% of diabetic subjects in their lifetime. An untreated ulcer further gets infected which causes necrosis leading to amputation of lower extremities. Early identification of risk factors and treatment for these chronic wounds would reduce health care costs and improve the quality of life for people with diabetes. Recent clinical investigations have shown that a series of factors including reduced oxygen delivery and disturbed metabolism have been observed on patients with foot ulceration due to diabetes. Also, these factors can impair the wound healing process. Optical techniques based on diffuse reflectance spectroscopy provide characteristic spectral finger prints shed light on tissue oxygenation levels and morphological composition of a tissue. This study deals with the application of diffuse reflectance intensity ratios based on oxyhemoglobin bands (R542/R580), ratios of oxy- and deoxy-hemoglobin bands (R580/R555), total hemoglobin concentration and hemoglobin oxygen saturation between normal and diabetic foot ulcer sites. Preliminary results obtained are found to be promising indicating the application of reflectance spectroscopy in the assessment of foot ulcer healing.

  4. In vivo water state measurements in breast cancer using broadband diffuse optical spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chung, S H; Cerussi, A E; Tromberg, B J [Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road, Irvine 92612, CA (United States); Klifa, C [Magnetic Resonance Science Center, Radiology, University of California, San Francisco, 505 Parnassus Avenue, Box 0628, San Francisco, CA 94143-0628 (United States); Baek, H M; Birgul, O; Gulsen, G [Tu and Yuen Center for Functional Onco Imaging, Department of Radiological Sciences, University of California, Irvine, 108 Irvine Hall, Irvine, CA, 92697-5020 (United States); Merritt, S I [Masimo Corporation, 40 Parker, Irvine, CA 92618 (United States); Hsiang, D [Department of Surgery, Chao Family Comprehensive Cancer Center, University of California, Irvine, Healthcare, 101 The City Drive South, Orange, CA 92868 (United States)], E-mail: bjtrombe@uci.edu

    2008-12-07

    Structural changes in water molecules are related to physiological, anatomical and pathological properties of tissues. Near infrared (NIR) optical absorption methods are sensitive to water; however, detailed characterization of water in thick tissues is difficult to achieve because subtle spectral shifts can be obscured by multiple light scattering. In the NIR, a water absorption peak is observed around 975 nm. The precise NIR peak's shape and position are highly sensitive to water molecular disposition. We introduce a bound water index (BWI) that quantifies shifts observed in tissue water absorption spectra measured by broadband diffuse optical spectroscopy (DOS). DOS quantitatively measures light absorption and scattering spectra and therefore reveals bound water spectral shifts. BWI as a water state index was validated by comparing broadband DOS to magnetic resonance spectroscopy, diffusion-weighted MRI and conductivity in bound water tissue phantoms. Non-invasive DOS measurements of malignant and normal breast tissues performed in 18 subjects showed a significantly higher fraction of free water in malignant tissues (p < 0.0001) compared to normal tissues. BWI of breast cancer tissues inversely correlated with Nottingham-Bloom-Richardson histopathology scores. These results highlight broadband DOS sensitivity to molecular disposition of water and demonstrate the potential of BWI as a non-invasive in vivo index that correlates with tissue pathology.

  5. Application of finite difference method in the study of diffusion with chemical kinetics of first order

    Directory of Open Access Journals (Sweden)

    Beltrán-Prieto Juan Carlos

    2016-01-01

    Full Text Available The mathematical modelling of diffusion of a bleaching agent into a porous material is studied in the present paper. Law of mass conservation was applied to analize the mass transfer of a reactant from the bulk into the external surface of a solid geometrically described as a flat plate. After diffusion of the reactant, surface reaction following kinetics of first order was considered to take place. The solution of the differential equation that described the process leaded to an equation that represents the concentration profile in function of distance, porosity and Thiele modulus. The case of interfacial mass resistance is also discused. In this case, finite difference method was used for the solution of the differential equation taking into account the respective boundary conditions. The profile of concentration can be obtained after numerical especification of Thiele modulus and Biot number.

  6. Technique for examining biological materials using diffuse reflectance spectroscopy and the kubelka-munk function

    Energy Technology Data Exchange (ETDEWEB)

    Alfano, Robert R.; Yang, Yuanlong

    2003-09-02

    Method and apparatus for examining biological materials using diffuse reflectance spectroscopy and the Kubelka-Munk function. In one aspect, the method is used to determine whether a tissue sample is cancerous or not and comprises the steps of (a) measuring the diffuse reflectance from the tissue sample at a first wavelength and at a second wavelength, wherein the first wavelength is a wavelength selected from the group consisting of 255-265 nm and wherein the second wavelength is a wavelength selected from the group consisting of 275-285 nm; (b) using the Kubelka-Munk function to transform the diffuse reflectance measurement obtained at the first and second wavelengths; and (c) comparing a ratio or a difference of the transformed Kubelka-Munk measurements at the first and second wavelengths to appropriate standards determine whether or not the tissue sample is cancerous. One can use the spectral profile of KMF between 250 nm to 300 nm to determine whether or not the tissue sample is cancerous or precancerous. According to the value at the first and second wavelengths determine whether or not the malignant tissue is invasive or mixed invasive and in situ or carcinoma in situ.

  7. Single-order laser high harmonics in XUV for ultrafast photoelectron spectroscopy of molecular wavepacket dynamics

    Directory of Open Access Journals (Sweden)

    Mizuho Fushitani

    2016-11-01

    Full Text Available We present applications of extreme ultraviolet (XUV single-order laser harmonics to gas-phase ultrafast photoelectron spectroscopy. Ultrashort XUV pulses at 80 nm are obtained as the 5th order harmonics of the fundamental laser at 400 nm by using Xe or Kr as the nonlinear medium and separated from other harmonic orders by using an indium foil. The single-order laser harmonics is applied for real-time probing of vibrational wavepacket dynamics of I2 molecules in the bound and dissociating low-lying electronic states and electronic-vibrational wavepacket dynamics of highly excited Rydberg N2 molecules.

  8. Fifth-order Raman spectroscopy of liquid benzene : Experiment and theory

    NARCIS (Netherlands)

    Milne, C. J.; Li, Y. L.; Jansen, T. L. C.; Huang, L.; Miller, R. J. D.

    2006-01-01

    The heterodyned fifth-order Raman response of liquid benzene has been measured and characterized by exploiting the passive-phase stabilization of diffractive optics. This result builds on our previous work with liquid carbon disulfide and extends the spectroscopy to a new liquid for the first time.

  9. Fifth-order Raman spectroscopy of liquid benzene : Experiment and theory

    NARCIS (Netherlands)

    Milne, C. J.; Li, Y. L.; Jansen, T. L. C.; Huang, L.; Miller, R. J. D.

    2006-01-01

    The heterodyned fifth-order Raman response of liquid benzene has been measured and characterized by exploiting the passive-phase stabilization of diffractive optics. This result builds on our previous work with liquid carbon disulfide and extends the spectroscopy to a new liquid for the first time.

  10. Diagnosis of breast cancer using diffuse optical spectroscopy from 500 to 1600 nm: comparison of classification methods

    Science.gov (United States)

    Nachabé, Rami; Evers, Daniel J.; Hendriks, Benno H. W.; Lucassen, Gerald W.; van der Voort, Marjolein; Rutgers, Emiel J.; Peeters, Marie-Jeanne Vrancken; van der Hage, Jos A.; Oldenburg, Hester S.; Wesseling, Jelle; Ruers, Theo J. M.

    2011-08-01

    We report on the use of diffuse optical spectroscopy analysis of breast spectra acquired in the wavelength range from 500 to 1600 nm with a fiber optic probe. A total of 102 ex vivo samples of five different breast tissue types, namely adipose, glandular, fibroadenoma, invasive carcinoma, and ductal carcinoma in situ from 52 patients were measured. A model deriving from the diffusion theory was applied to the measured spectra in order to extract clinically relevant parameters such as blood, water, lipid, and collagen volume fractions, β-carotene concentration, average vessels radius, reduced scattering amplitude, Mie slope, and Mie-to-total scattering fraction. Based on a classification and regression tree algorithm applied to the derived parameters, a sensitivity-specificity of 98%-99%, 84%-95%, 81%-98%, 91%-95%, and 83%-99% were obtained for discrimination of adipose, glandular, fibroadenoma, invasive carcinoma, and ductal carcinoma in situ, respectively; and a multiple classes overall diagnostic performance of 94%. Sensitivity-specificity values obtained for discriminating malignant from nonmalignant tissue were compared to existing reported studies by applying the different classification methods that were used in each of these studies. Furthermore, in these reported studies, either lipid or β-carotene was considered as adipose tissue precursors. We estimate both chromophore concentrations and demonstrate that lipid is a better discriminator for adipose tissue than β-carotene.

  11. Numerical simulation of transonic limit cycle oscillations using high-order low-diffusion schemes

    Science.gov (United States)

    Wang, Baoyuan; Zha, Ge-Cheng

    2010-05-01

    This paper simulates the NLR7301 airfoil limit cycle oscillation (LCO) caused by fluid-structure interaction (FSI) using Reynolds averaged Navier-Stokes equations (RANS) coupled with Spalart-Allmaras (S-A) one-equation turbulence model. A low diffusion E-CUSP (LDE) scheme with 5th order weighted essentially nonoscillatory scheme (WENO) is employed to calculate the inviscid fluxes. A fully conservative 4th order central differencing is used for the viscous terms. A fully coupled fluid-structural interaction model is employed. For the case computed in this paper, the predicted LCO frequency, amplitudes, averaged lift and moment, all agree excellently with the experiment performed by Schewe et al. The solutions appear to have bifurcation and are dependent on the initial fields or initial perturbation. The developed computational fluid dynamics (CFD)/computational structure dynamics (CSD) simulation is able to capture the LCO with very small amplitudes measured in the experiment. This is attributed to the high order low diffusion schemes, fully coupled FSI model, and the turbulence model used. This research appears to be the first time that a numerical simulation of LCO matches the experiment. The simulation confirms several observations of the experiment.

  12. Persistent Spins in the Linear Diffusion Approximation of Phase Ordering and Zeros of Stationary Gaussian Processes

    Science.gov (United States)

    Derrida, Bernard; Hakim, Vincent; Zeitak, Reuven

    1996-09-01

    The fraction r\\(t\\) of spins which have never flipped up to time t is studied within a linear diffusion approximation to phase ordering. Numerical simulations show that r\\(t\\) decays with time like a power law with a nontrivial exponent θ which depends on the space dimension. The dynamics is a special case of a stationary Gaussian process of known correlation function. The exponent θ is given by the asymptotic decay of the probability distribution of intervals between consecutive zero crossings. An approximation based on the assumption that successive zero crossings are independent random variables gives values of θ in close agreement with the results of simulations.

  13. Carrier diffusion and higher order transversal modes in spectral dynamics of the semiconductor laser

    DEFF Research Database (Denmark)

    Buus, Jens; Danielsen, Magnus

    1977-01-01

    The dynamic and spectral behavior of the semiconductor stripe laser has been investigated. For this purpose the rate equations have been generalized to include several longitudinal and transversal modes, spontaneous emission into the active modes, and position dependence of the electron density...... through a term describing the charge-carrier diffusion in the plane of the active layer. The parameters used for solving these equations are found by theoretical and experimental considerations. The results show a broadening of the spectrum together with a significant content of higher order transversal...

  14. Longitudinal diffusion behavior of hemicyanine dyes across phospholipid vesicle membranes as studied by second-harmonic generation and fluorescence spectroscopies.

    Science.gov (United States)

    Yamaguchi, Akira; Nakano, Masaki; Nochi, Kimihisa; Yamashita, Tomohisa; Morita, Kotaro; Teramae, Norio

    2006-10-01

    The adsorption and longitudinal diffusion behaviors of a series of hemicyanine dyes to phospholipid vesicle membranes were studied by second-harmonic generation (SHG) and fluorescence spectroscopies. It was observed that the longitudinal diffusion of cationic hemicyanine dyes takes place immediately after the initial adsorption of these dyes to the outer surface of the vesicle membrane. In contrast, hardly any amount of a zwitterionic hemicyanine dye with a sulfonate group diffused across the vesicle membrane within the measurement time (<2000 s). Based on the difference in the time-course responses of SHG and fluorescence spectroscopies for all of the hemicyanine dyes tested, we propose that hydration of the sulfonate group is mainly responsible for the low diffusivity of the zwitterionic hemicyanine dye.

  15. Quasi first-order Hermite Gaussian beam for enhanced sensitivity in Sagnac interferometer photothermal deflection spectroscopy.

    Science.gov (United States)

    Shiokawa, Naoyuki; Tokunaga, Eiji

    2016-05-30

    The detection sensitivity of a Sagnac interferometer photothermal deflection spectroscopy was enhanced by changing the probe beam pattern from zero-order to a quasi-first-order Hermite Gaussian (QHG) beam. The nature of the higher order HG mode, where the beam pattern is preserved during propagation with an increased field gradient, is utilized to enhance the measurement sensitivity. In this spectroscopy, the lateral beam deflection due to the photothermal effect is sensitively detected as a change in the interference light intensity. The change in intensity is amplified due to the higher field gradient of the QHG(1,0) beam at the photodetector. This amplification effect was both numerically and experimentally demonstrated to obtain twofold improvement in the signal-to-noise ratio.

  16. Impact of fluoxetine on the human brain in multiple sclerosis as quantified by proton magnetic resonance spectroscopy and diffusion tensor imaging.

    Science.gov (United States)

    Sijens, Paul E; Mostert, Jop P; Irwan, Roy; Potze, Jan Hendrik; Oudkerk, Matthijs; De Keyser, Jacques

    2008-12-30

    The antidepressant fluoxetine stimulates astrocytic glycogenolysis, which serves as an energy source for axons. In multiple sclerosis patients fluoxetine administration may improve energy supply in neuron cells and thus inhibit axonal degeneration. In a preliminary pilot study, 15 patients with multiple sclerosis (MS) were examined by diffusion tensor imaging (DTI) and (1)H magnetic resonance spectroscopy (MRS) in order to quantify the brain tissue diffusion properties (fractional anisotropy, apparent diffusion coefficient) and metabolite levels (choline, creatine and N-acetylaspartate) in cortical gray matter brain tissue, in normal appearing white matter and in white matter lesions. After oral administration of fluoxetine (20 mg/day) for 1 week, the DTI and MRS measurements were repeated and after treatment with a higher dose (40 mg/day) during the next week, a third series of DTI/MRS examinations was performed in order to assess any changes in diffusion properties and metabolism. One trend was observed in gray matter tissue, a decrease of choline measured at weeks 1 and 2 (significant in a subgroup of 11 relapsing remitting/secondary progressive MS patients). In white matter lesions, the apparent diffusion coefficient was increased at week 1 and N-acetylaspartate was increased at week 2 (both significant). These preliminary results provide evidence of a neuroprotective effect of fluoxetine in MS by the observed partial normalization of the structure-related MRS parameter N-acetylaspartate in white matter lesions.

  17. A high-order discontinuous Galerkin method for unsteady advection-diffusion problems

    Science.gov (United States)

    Borker, Raunak; Farhat, Charbel; Tezaur, Radek

    2017-03-01

    A high-order discontinuous Galerkin method with Lagrange multipliers is presented for the solution of unsteady advection-diffusion problems in the high Péclet number regime. It operates directly on the second-order form of the governing equation and does not require any stabilization. Its spatial basis functions are chosen among the free-space solutions of the homogeneous form of the partial differential equation obtained after time-discretization. It also features Lagrange multipliers for enforcing a weak continuity of the approximated solution across the element interface boundaries. This leads to a system of differential-algebraic equations which are time-integrated by an implicit family of schemes. The numerical stability of these schemes and the well-posedness of the overall discretization method are supported by a theoretical analysis. The performance of this method is demonstrated for various high Péclet number constant-coefficient model flow problems.

  18. Verification of high-order mixed FEM solution of transient Magnetic diffusion problems

    Energy Technology Data Exchange (ETDEWEB)

    Rieben, R; White, D A

    2005-05-12

    We develop and present high order mixed finite element discretizations of the time dependent electromagnetic diffusion equations for solving eddy current problems on 3D unstructured grids. The discretizations are based on high order H(grad), H(curl) and H(div) conforming finite element spaces combined with an implicit and unconditionally stable generalized Crank-Nicholson time differencing method. We develop three separate electromagnetic diffusion formulations, namely the E (electric field), H (magnetic field) and the A-{phi} (potential) formulations. For each formulation, we also provide a consistent procedure for computing the secondary variables F (current flux density) and B (magnetic flux density), as these fields are required for the computation of electromagnetic force and heating terms. We verify the error convergence properties of each formulation via a series of numerical experiments on canonical problems with known analytic solutions. The key result is that the different formulations are equally accurate, even for the secondary variables J and B, and hence the choice of which formulation to use depends mostly upon relevance of the Natural and Essential boundary conditions to the problem of interest. In addition, we highlight issues with numerical verification of finite element methods which can lead to false conclusions on the accuracy of the methods.

  19. Note: A simple broad bandwidth undersampling frequency-domain digital diffuse optical spectroscopy system

    Science.gov (United States)

    Jung, Justin; Istfan, Raeef; Roblyer, Darren

    2014-07-01

    Near-Infrared frequency-domain technologies, such as Diffuse Optical Spectroscopy (DOS), have demonstrated growing potential in a number of clinical applications. The broader dissemination of this technology is limited by the complexity and cost of instrumentation. We present here a simple system constructed with off-the-shelf components that utilizes undersampling for digital frequency-domain dDOS measurements. Broadband RF sweeps (50-300 MHz) were digitally sampled at 25 MSPS; amplitude, phase, and optical property extractions were within 5% of network analyzer derived values. The use of undersampling for broad bandwidth dDOS provides a significant reduction in complexity, power consumption, and cost compared with high-speed ADCs and analog techniques.

  20. Evaluation of apparent viscosity of Para rubber latex by diffuse reflection near-infrared spectroscopy.

    Science.gov (United States)

    Sirisomboon, Panmanas; Chowbankrang, Rawiphan; Williams, Phil

    2012-05-01

    Near-infrared spectroscopy in diffuse reflection mode was used to evaluate the apparent viscosity of Para rubber field latex and concentrated latex over the wavelength range of 1100 to 2500 nm, using partial least square regression (PLSR). The model with ten principal components (PCs) developed using the raw spectra accurately predicted the apparent viscosity with correlation coefficient (r), standard error of prediction (SEP), and bias of 0.974, 8.6 cP, and -0.4 cP, respectively. The ratio of the SEP to the standard deviation (RPD) and the ratio of the SEP to the range (RER) for the prediction were 4.4 and 16.7, respectively. Therefore, the model can be used for measurement of the apparent viscosity of field latex and concentrated latex in quality assurance and process control in the factory.

  1. Inexpensive diffuse reflectance spectroscopy system for measuring changes in tissue optical properties

    Science.gov (United States)

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

    2014-10-01

    The measurement of changes in blood volume in tissue is important for monitoring the effects of a wide range of therapeutic interventions, from radiation therapy to skin-flap transplants. Many systems available for purchase are either expensive or difficult to use, limiting their utility in the clinical setting. A low-cost system, capable of measuring changes in tissue blood volume via diffuse reflectance spectroscopy is presented. The system consists of an integrating sphere coupled via optical fibers to a broadband light source and a spectrometer. Validation data are presented to illustrate the accuracy and reproducibility of the system. The validity and utility of this in vivo system were demonstrated in a skin blanching/reddening experiment using epinephrine and lidocaine, and in a study measuring the severity of radiation-induced erythema during radiation therapy.

  2. Preliminary study on diffuse axonal injury by Fourier transform infrared spectroscopy histopathology imaging.

    Science.gov (United States)

    Yang, Tiantong; He, Guanglong; Zhang, Xiang; Chang, Lin; Zhang, Haidong; Ripple, Mary G; Fowler, David R; Li, Ling

    2014-01-01

    The objective of this study was to evaluate the application of Fourier transform infrared (FTIR) spectroscopy for detecting diffuse axonal injury (DAI) in a mouse model. Brain tissues from DAI mouse model were prepared with H&E, silver, and β-amyloid precursor protein (β-APP) immunohistochemistry stains and were also studied with FTIR. The infrared spectrum images showed high absorption of amide II in the subcortical white matter of the experimental mouse brain, while there was no obvious expression of amide II in the control mouse brain. The areas with high absorption of amide II were in the same distribution as the DAI region confirmed by the silver and β-APP studies. The result suggests that high absorption of amide II correlates with axonal injury. The use of FTIR imaging allows the biochemical changes associated with DAI pathologies to be detected in the tissues, thus providing an important adjunct method to the current conventional pathological diagnostic techniques.

  3. Diffuse Reflectance Infrared Fourier Transform Spectroscopy for the Determination of Asbestos Species in Bulk Building Materials

    Directory of Open Access Journals (Sweden)

    Grazia Accardo

    2014-01-01

    Full Text Available Diffuse reflectance infrared Fourier transform (DRIFT spectroscopy is a well-known technique for thin film characterization. Since all asbestos species exhibit intense adsorptions peaks in the 4000–400 cm−1 region of the infrared spectrum, a quantitative analysis of asbestos in bulk samples by DRIFT is possible. In this work, different quantitative analytical procedures have been used to quantify chrysotile content in bulk materials produced by building requalification: partial least squares (PLS chemometrics, the Linear Calibration Curve Method (LCM and the Method of Additions (MoA. Each method has its own pros and cons, but all give affordable results for material characterization: the amount of asbestos (around 10%, weight by weight can be determined with precision and accuracy (errors less than 0.1.

  4. Diffusion-weighted imaging and proton MR spectroscopy in the characterization of acute disseminated encephalomyelitis

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanya, K.S.; Kovoor, J.M.E.; Jayakumar, P.N.; Ravishankar, S.; Kamble, R.B. [National Institute of Mental Health and Neurosciences, Department of Neuroimaging and Interventional Radiology, Bangalore, Karnataka (India); Panicker, J.; Nagaraja, D. [National Institute of Mental Health and Neurosciences, Department of Neurology, Bangalore (India)

    2007-02-15

    Acute disseminated encephalomyelitis (ADEM) is usually a monophasic illness characterized by multiple lesions involving gray and white matter. Quantitative MR techniques were used to characterize and stage these lesions. Eight patients (seven males and one female; mean age 19 years, range 5 to 36 years) were studied using conventional MRI (T2- and T1-weighted and FLAIR sequences), diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (MRS). Apparent diffusion coefficient (ADC) values and MRS ratios were calculated for the lesion and for normal-appearing white matter (NAWM). Three patients were imaged in the acute stage (within 7 days of the onset of neurological symptoms) and five in the subacute stage (after 7 days from the onset of symptoms). ADC values in NAWM were in the range 0.7-1.24 x 10{sup -3} mm/s{sup 2} (mean 0.937 {+-} 0.17 mm/s{sup 2}). ADC values of ADEM lesions in the acute stage were in the range 0.37-0.68 x 10{sup -3} mm/s{sup 2} (mean 0.56 {+-} 0.16 mm/s{sup 2}) and 1.01-1.31 x 10{sup -3} mm/s{sup 2} (mean 1.24 {+-} 0.13 mm/s{sup 2}) in the subacute stage. MRS ratios were obtained for all patients. NAA/Cho ratios were in the range 1.1-3.5 (mean 1.93 {+-} 0.86) in the NAWM. NAA/Cho ratios within ADEM lesions in the acute stage were in the range 0.63-1.48 (mean 1.18 {+-} 0.48) and 0.29-0.84 (mean 0.49 {+-} 0.22) in the subacute stage. The ADC values, NAA/Cho and Cho/Cr ratios were significantly different between lesions in the acute and subacute stages (P < 0.001, P < 0.027, P < 0.047, respectively). ADC values were significantly different between lesions in the acute (P < 0.009) and subacute stages (P < 0.005) with NAWM. In addition, NAA/Cho and Cho/Cr ratios were significantly different between lesions in the subacute stage and NAWM (P < 0.006, P < 0.007, respectively). ADEM lesions were characterized in the acute stage by restricted diffusion and in the subacute stage by free diffusion and a decrease in NAA/Cho ratios

  5. Diffuse optical spectroscopy monitoring of oxygen state and hemoglobin concentration during SKBR-3 tumor model growth

    Science.gov (United States)

    Orlova, A. G.; Kirillin, M. Yu; Volovetsky, A. B.; Shilyagina, N. Yu; Sergeeva, E. A.; Golubiatnikov, G. Yu; Turchin, I. V.

    2017-01-01

    Tumor oxygenation and hemoglobin content are the key indicators of the tumor status which can be efficiently employed for prognosis of tumor development and choice of treatment strategy. We report on monitoring of these parameters in SKBR-3 (human breast adenocarcinoma) tumors established as subcutaneous tumor xenografts in athymic nude mice by diffuse optical spectroscopy (DOS). A simple continuous wave fiber probe DOS system is employed. Optical properties extraction approach is based on diffusion approximation. Statistically significant difference between measured values of normal tissue and tumor are demonstrated. Hemoglobin content in tumor increases from 7.0  ±  4.2 μM to 30.1  ±  16.1 μM with tumor growth from 150  ±  80 mm3 to 1300  ±  650 mm3 which is determined by gradual increase of deoxyhemoglobin content while measured oxyhemoglobin content does not demonstrate any statistically significant variations. Oxygenation in tumor falls quickly from 52.8  ±  24.7% to 20.2  ±  4.8% preceding acceleration of tumor growth. Statistical analysis indicated dependence of oxy-, deoxy- and total hemoglobin on tumor volume (p  Pearson’s correlation coefficient equals 0.8).

  6. Optical clearing of melanoma in vivo: characterization by diffuse reflectance spectroscopy and optical coherence tomography

    Science.gov (United States)

    Pires, Layla; Demidov, Valentin; Vitkin, I. Alex; Bagnato, Vanderlei; Kurachi, Cristina; Wilson, Brian C.

    2016-08-01

    Melanoma is the most aggressive type of skin cancer, with significant risk of fatality. Due to its pigmentation, light-based imaging and treatment techniques are limited to near the tumor surface, which is inadequate, for example, to evaluate the microvascular density that is associated with prognosis. White-light diffuse reflectance spectroscopy (DRS) and near-infrared optical coherence tomography (OCT) were used to evaluate the effect of a topically applied optical clearing agent (OCA) in melanoma in vivo and to image the microvascular network. DRS was performed using a contact fiber optic probe in the range from 450 to 650 nm. OCT imaging was performed using a swept-source system at 1310 nm. The OCT image data were processed using speckle variance and depth-encoded algorithms. Diffuse reflectance signals decreased with clearing, dropping by ˜90% after 45 min. OCT was able to image the microvasculature in the pigmented melanoma tissue with good spatial resolution up to a depth of ˜300 μm without the use of OCA; improved contrast resolution was achieved with optical clearing to a depth of ˜750 μm in tumor. These findings are relevant to potential clinical applications in melanoma, such as assessing prognosis and treatment responses. Optical clearing may also facilitate the use of light-based treatments such as photodynamic therapy.

  7. Vaginal hemodynamic changes during sexual arousal in a rat model by diffuse optical spectroscopy (Conference Presentation)

    Science.gov (United States)

    Jeong, Hyeryun; Seong, Myeongsu; Lee, Hyun-Suk; Park, Kwangsung; Kim, Jae Gwan

    2017-02-01

    Not only men suffer from sexual dysfunction, but the number of women who have sexual dysfunction rises. Therefore, it is necessary to develop an objective diagnostic technique to examine the sexual dysfunction of female patients, who are afflicted with the disorders. For this purpose, we developed a diffuse optical spectroscopy (DOS) probe to measure the change of oxy-, deoxy-, and total hemoglobin concentration along with blood flow from vaginal wall of female rats. A cylindrical stainless steel DOS probe with a diameter of 3 mm was designed for the vaginal wall of rats which consisted of two lasers (785 and 850nm) and two spectrometers with a separation of 2 mm. A thermistor was placed on the top of the probe to measure the temperature change from vaginal wall during experiments. A modified Beer-Lambert's law is utilized to acquire the changes of oxy-, deoxy-, and total hemoglobin, and blood flow information is obtained by diffuse speckle contrast analysis technique. For the experiments, Sprague Dawley ( 400 g) female rats were divided into two groups (control and vaginal dryness model). Vaginal oxygenation, blood flow and temperature were continuously monitored before and after sexual around induced by apomorphine. After the measurement, histologic examination was performed to support the results from DOS probe in the vaginal wall. The hemodynamic information acquired by the DOS probe can be utilized to establish an objective and accurate standard of the female sexual disorders.

  8. High Frequency Sampling of TTL Pulses on a Raspberry Pi for Diffuse Correlation Spectroscopy Applications.

    Science.gov (United States)

    Tivnan, Matthew; Gurjar, Rajan; Wolf, David E; Vishwanath, Karthik

    2015-08-12

    Diffuse Correlation Spectroscopy (DCS) is a well-established optical technique that has been used for non-invasive measurement of blood flow in tissues. Instrumentation for DCS includes a correlation device that computes the temporal intensity autocorrelation of a coherent laser source after it has undergone diffuse scattering through a turbid medium. Typically, the signal acquisition and its autocorrelation are performed by a correlation board. These boards have dedicated hardware to acquire and compute intensity autocorrelations of rapidly varying input signal and usually are quite expensive. Here we show that a Raspberry Pi minicomputer can acquire and store a rapidly varying time-signal with high fidelity. We show that this signal collected by a Raspberry Pi device can be processed numerically to yield intensity autocorrelations well suited for DCS applications. DCS measurements made using the Raspberry Pi device were compared to those acquired using a commercial hardware autocorrelation board to investigate the stability, performance, and accuracy of the data acquired in controlled experiments. This paper represents a first step toward lowering the instrumentation cost of a DCS system and may offer the potential to make DCS become more widely used in biomedical applications.

  9. High Frequency Sampling of TTL Pulses on a Raspberry Pi for Diffuse Correlation Spectroscopy Applications

    Directory of Open Access Journals (Sweden)

    Matthew Tivnan

    2015-08-01

    Full Text Available Diffuse Correlation Spectroscopy (DCS is a well-established optical technique that has been used for non-invasive measurement of blood flow in tissues. Instrumentation for DCS includes a correlation device that computes the temporal intensity autocorrelation of a coherent laser source after it has undergone diffuse scattering through a turbid medium. Typically, the signal acquisition and its autocorrelation are performed by a correlation board. These boards have dedicated hardware to acquire and compute intensity autocorrelations of rapidly varying input signal and usually are quite expensive. Here we show that a Raspberry Pi minicomputer can acquire and store a rapidly varying time-signal with high fidelity. We show that this signal collected by a Raspberry Pi device can be processed numerically to yield intensity autocorrelations well suited for DCS applications. DCS measurements made using the Raspberry Pi device were compared to those acquired using a commercial hardware autocorrelation board to investigate the stability, performance, and accuracy of the data acquired in controlled experiments. This paper represents a first step toward lowering the instrumentation cost of a DCS system and may offer the potential to make DCS become more widely used in biomedical applications.

  10. Time-resolved spatially offset Raman spectroscopy for depth analysis of diffusely scattering layers.

    Science.gov (United States)

    Iping Petterson, Ingeborg E; Dvořák, Patrick; Buijs, Joost B; Gooijer, Cees; Ariese, Freek

    2010-12-01

    The objective of this study is to use time-resolved (TR) Raman spectroscopy, spatially offset Raman spectroscopy (SORS), and a combination of these approaches to obtain high quality Raman spectra from materials hidden underneath an opaque layer. Both TR Raman and SORS are advanced techniques that allow for an increased relative selectivity of photons from deeper layers within a sample. Time-resolved detection reduces fluorescence background, and the selectivity for the second layer is improved. By combining this with spatially offset excitation we additionally increased selectivity for deeper layers. Test samples were opaque white polymer blocks of several mm thicknesses. Excitation was carried out with a frequency-doubled Ti:sapphire laser at 460 nm, 3 ps pulse width and 76 MHz repetition rate. Detection was either with a continuous-wave CCD camera or in time-resolved mode using an intensified CCD camera with a 250 ps gate width. The Raman photons were collected in backscatter mode, with or without lateral offset. By measuring the delay of the Raman signal from the second layer (polyethylene terephthalate/PET/Arnite), the net photon migration speeds through Teflon, polythene, Delrin and Nylon were determined. Raman spectra could be obtained from a second layer of PET through Teflon layers up to 7 mm of thickness. The ability to obtain chemical information through layers of diffusely scattering materials has powerful potential for biomedical applications.

  11. Diffusion tensor imaging and magnetic resonance spectroscopy of the brain in a patient with Sturge-Weber syndrome.

    Science.gov (United States)

    Sijens, P E; Gieteling, E W; Meiners, L C; Sival, D A; Potze, J H; Irwan, R; Oudkerk, M

    2006-11-01

    Quantitative brain MR spectroscopy (MRS) and diffusion tensor imaging (DTI) were used to characterize one patient with Sturge-Weber syndrome. Choline increases and N-acetylaspartate decreases were observed in pathologic frontal gray matter tissue compared to contralateral unaffected brain tissue without any change in the diffusion tensor imaging parameters (fractional anisotropy, apparent diffusion coefficient). The N-acetylaspartate decreases and/or choline increases observed here and in eight previously described Sturge-Weber patients probably reflect neuronal loss or dysfunction and demyelination as a result of recurrent seizures.

  12. Diffusion Tensor Imaging and Magnetic Resonance Spectroscopy of the Brain in a Patient with Sturge-Weber Syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Sijens, P.E.; Gieteling, E.W.; Meiners, L.C.; Sival, D.A.; Potze, J.H.; Irwan, R.; Oudkerk, M. [Univ. Medical Center Groningen (Netherlands). Dept. of Radiology

    2006-11-15

    Quantitative brain MR spectroscopy (MRS) and diffusion tensor imaging (DTI) were used to characterize one patient with Sturge-Weber syndrome. Choline increases and N-acetylaspartate decreases were observed in pathologic frontal gray matter tissue compared to contralateral unaffected brain tissue without any change in the diffusion tensor imaging parameters (fractional anisotropy, apparent diffusion coefficient). The N-acetylaspartate decreases and/or choline increases observed here and in eight previously described Sturge-Weber patients probably reflect neuronal loss or dysfunction and demyelination as a result of recurrent seizures.

  13. Fourth-order analysis of a diffusive lattice Boltzmann method for barrier coatings.

    Science.gov (United States)

    Strand, Kyle T; Feickert, Aaron J; Wagner, Alexander J

    2017-06-01

    We examine the applicability of diffusive lattice Boltzmann methods to simulate the fluid transport through barrier coatings, finding excellent agreement between simulations and analytical predictions for standard parameter choices. To examine more interesting non-Fickian behavior and multiple layers of different coatings, it becomes necessary to explore a wider range of parameters. However, such a range of parameters exposes deficiencies in such an implementation. To investigate these discrepancies, we examine the form of higher-order terms in the hydrodynamic limit of our lattice Boltzmann method. We identify these corrections to fourth order and validate these predictions with high accuracy. However, it is observed that the validated correction terms do not fully explain the bulk of observed error. This error was instead caused by the standard finite boundary conditions for the contact of the coating with the imposed environment. We identify a self-consistent form of these boundary conditions for which these errors are dramatically reduced. The instantaneous switching used as a boundary condition for the barrier problem proves demanding enough that any higher-order corrections meaningfully contribute for a small range of parameters. There is a large parameter space where the agreement between simulations and analytical predictions even in the second-order form are below 0.1%, making further improvements to the algorithm unnecessary for such an application.

  14. Spectroscopie du Furanne et du Thiophene Par Diffusion Inelastique D'electrons

    Science.gov (United States)

    Lotfi, Said

    Nous avons etudie les molecules de furanne ( rm C_4H_4O) et de thiophene (rm C_4H_4O) au moyen de la spectroscopie de diffusion inelastique d'electrons. Pour (rm C_4H_4O), les spectres realises dans differentes conditions d'energie d'impact et d'angle de diffusion contiennent des singularites ou des families de pics correspondant a: (1) des vibrations de l'etat fondamental dans le domaine 0-0.5 eV, (2) des etats triplets ^3 B_1 et ^3 A_1 qui dominent la region 3-5.5 eV, (3) des etats de valences, entre 5 et 10 eV, dont certains son accompagnes de progressions vibrationnelles, soit ~ A _1B_2, ~ B ^1A_1 et ~ C ^1A_1, (4) toujours entre 5 et 10 eV, deux series de Ryhdberg (rm 1a_2to nda_2 et rm 1a_2to npb_2) qui convergent vers la premiere limite d'ionisation de la molecule, avec une progression vibrationnelle associee au mdoe nu_4 pour la seconde, et une troisieme serie (rm 2b_1to nsa_1 ) convergent vers la seconde limite d'ionisation accompagnee de la progression de mode nu _1. Pour rm C_4H_4S, nos spectres presentent les memes etats de vibration et les memes etats triplets que pour rm C_4H _4O. Nous avons releve egalement, dans la region de 5 a 10 eV, des etats de valence ~ A ^1A_1 (ou ~ A ^1B_2), ~ B ^1A_1 (ou ~ B ^1B _2) et ~ C ^1A_1 (ou ~ C ^1B_2). Pour la premiere fois, par la spectroscopie de diffusion inelastique d'electrons, de nombreux pics ont ete identifies et attribues, dans le cadre de ce travail. Il s'agit, notamment, des etats de vibration de l'etat electronique fondamental de ces molecules et egalement de certains etats de Rydberg dans le cas du furanne.

  15. Using diffuse reflectance spectroscopy (DRS) for qualitative examination of iron minerals formed in a hydromorphic soil

    Science.gov (United States)

    Ringer, Marianna; Kiss, Klaudia; Németh, Tibor; Sipos, Péter; Szalai, Zoltán

    2016-04-01

    The method of diffuse reflectance spectroscopy (DRS) allows a large number of measurements in a rapid, non-destructive mode and does not require complex sample preparation. Based on the recorded wavelength-reflectance spectra, the simultaneous investigation of various soil parameters such as colour, mineral composition, organic matter and moisture content is possible. Several publications have presented results of the qualitative and quantitative analysis of iron-oxides containing trivalent iron (primarily hematite, goethite) by DRS. These iron minerals are usually formed in soils and sediments under surface conditions. Nevertheless in the case of hydromorhic soils water saturation can result iron mineral formation in the absence of oxygen. However, the related soil forming process leads to the appearance of ferrous iron-hydroxides (green rust) in the soil profile, in the literature no reference was found discussing the investigation of samples from reduced soil conditions by DRS method. Our aim was to reveal if DRS is suitable to perform qualitative characterization of both ferrous and ferric iron-oxide and hydroxide minerals of waterlogged soils. In the present study samples from a sandy meadow soil (calcic, gleyic Phaeozem ferric, arenic) profile were examined in the laboratory using an UV-Vis-NIR spectrophotometer with a diffuse reflectance attachement. Pedogenic iron minerals were characterized through spectral transformations and by comparison with spectrum database and literature data. The results were compared with data obtained from widely used routine methods. X-ray powder diffraction (XRD) for the determination of mineral composition, X-ray fluorescence spectroscopy (XRF) for total iron content and selective chemical dissolution (SCD) for the amorphous and crystalline iron content were presented. Although iron oxide minerals are usually at low concentrations (approx. 0,1%) or present in a poorly crystalline form, our results show that the presence of

  16. Probing Cu Diffusion Barrier Layers on Porous Low-Dielectric-Constant Films by Posireonium Annihilation Lifetime Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    HU Yi-Fan; SUN Jia-Ning; Gidley D.W.

    2005-01-01

    @@ Two kinds of Cu diffusion barrier layers, sealedfilms and capped fi1ms, on nanoporous low-dielectric-constant filmsare investigated by positronium annihilation lifetime spectroscopy (PALS). We have found that the minimumthickness of Ta to form an effective diffusion barrier is affected by the pore size. The films with large poresrequire thick barrier layers to form effective diffusion barriers. In addition, a possible ultra-thin diffusion barrier,i.e. a plasma-induced densification layer, has also been investigated. The PALS data confirm that a porouslow-dielectric-constant thin film can be shrunk by exposure to plasma. This shrinkage is confined to a surfacelayer of collapsed pores and forms a dense layer. The dense layer tends to behave as Ps (positronium) diffusionbarriers. Indeed, the controlled thin "skin" layer could prevent Cu diffusion into the underlying dielectrics.

  17. A partial least squares model for non-volatile residue quantification using diffuse reflectance infrared reflectance spectroscopy

    Science.gov (United States)

    Chen, Amylynn; Moision, Robert M.

    2016-09-01

    Traditionally, quantification of non-volatile residue (NVR) on surfaces relevant to space systems has been performed using solvent wipes for NVR removal followed by gravimetric analysis. In this approach the detectable levels of NVR are ultimately determined by the mass sensitivity of the analytical balance employed. Unfortunately, for routine samples, gravimetric measurement requires large sampling areas, on the order of a square foot, in order to clearly distinguish sample and background levels. Diffuse Reflectance Infrared Reflectance Spectroscopy (DRIFTS) is one possible alternative to gravimetric analysis for NVR measurement. DRIFTS is an analytical technique used for the identification and quantification of organic compounds that has two primary advantages relative to gravimetric based methods: increased sensitivity and the ability to identify classes of organic species present. However, the use of DRIFTS is not without drawbacks, most notably repeatability of sample preparation and the additive quantification uncertainty arising from overlapping infrared signatures. This can result in traditional calibration methods greatly overestimating the concentration of species in mixtures. In this work, a partial least squares (PLS) regression model is shown to be an effective method for removing the over prediction error of a three component mixture of common contaminant species.

  18. Real-time in vivo tissue characterization with diffuse reflectance spectroscopy during transthoracic lung biopsy: a clinical feasibility study

    NARCIS (Netherlands)

    Spliethoff, Jarich; Prevoo, Warner; Meier, Mark A.J.; de Jong, Jeroen; Evers, Daniel; Evers, Daniel J.; Sterenborg, Hendricus J.C.M.; Lucassen, Gerald; Lucassen, Gerald W.; Hendriks, Benno H.W.; Ruers, Theo J.M.

    2016-01-01

    Purpose: This study presents the first in vivo real-time tissue characterization during image-guided percutaneous lung biopsies using diffuse reflectance spectroscopy (DRS) sensing at the tip of a biopsy needle with integrated optical fibers. Experimental Design: Tissues from 21 consented patients

  19. Diagnosis of breast cancer using diffuse optical spectroscopy from 500 to 1600 nm: a comparison of classification methods

    NARCIS (Netherlands)

    Nachabe, R.; Evers, D.; Hendriks, B.H.W.; Lucassen, G.W.; Van der Voort, M.; Wesseling, J.; Rutgers, E. J.; Vrancken Peeters, M.J.; Hage, J.A.van der; Oldenbeng, H.S.; Ruers, T.

    2011-01-01

    We report on the use of diffuse optical spectroscopy analysis of breast spectra acquired in the wavelength range from 500 to 1600 nm with a fiber optic probe. A total of 102 ex vivo samples of five different breast tissue types, namely adipose, glandular, fibroadenoma, invasive carcinoma and ductal

  20. Easy measurement of diffusion coefficients of EGFP-tagged plasma membrane proteins using k-space Image Correlation Spectroscopy

    DEFF Research Database (Denmark)

    Christensen, Eva Arnspang; Koffman, Jennifer Skaarup; Marlar, Saw

    2014-01-01

    Lateral diffusion and compartmentalization of plasma membrane proteins are tightly regulated in cells and thus, studying these processes will reveal new insights to plasma membrane protein function and regulation. Recently, k-Space Image Correlation Spectroscopy (kICS)1 was developed to enable ro...

  1. Diagnosis of breast cancer using diffuse optical spectroscopy from 500 to 1600 nm: comparison of classification methods

    NARCIS (Netherlands)

    Nachabé, Rami; Evers, Daniel J.; Hendriks, Benno H.W.; Lucassen, Gerald W.; Voort, van der Marjolein; Rutgers, Emiel J.; Vrancken Peeters, Marie-Jeanne; Hage, van der Jos A.; Oldenburg, Hester S.; Wesseling, Jelle; Ruers, Theo J.M.

    2011-01-01

    We report on the use of diffuse optical spectroscopy analysis of breast spectra acquired in the wavelength range from 500 to 1600 nm with a fiber optic probe. A total of 102 ex vivo samples of five different breast tissue types, namely adipose, glandular, fibroadenoma, invasive carcinoma, and ductal

  2. Diagnosis of breast cancer using diffuse optical spectroscopy from 500 to 1600 nm: a comparison of classification methods

    NARCIS (Netherlands)

    Nachabe, R.; Evers, D.; Hendriks, B.H.W.; Lucassen, G.W.; Van der Voort, M.; Wesseling, J.; Rutgers, E. J.; Vrancken Peeters, M.J.; Hage, J.A.van der; Oldenbeng, H.S.; Ruers, T.

    2011-01-01

    We report on the use of diffuse optical spectroscopy analysis of breast spectra acquired in the wavelength range from 500 to 1600 nm with a fiber optic probe. A total of 102 ex vivo samples of five different breast tissue types, namely adipose, glandular, fibroadenoma, invasive carcinoma and ductal

  3. Diffusion tensor imaging and magnetic resonance spectroscopy of the brain in a patient with Sturge-Weber syndrome

    NARCIS (Netherlands)

    Sijens, P. E.; Gieteling, E. W.; Meiners, L. C.; Sival, D. A.; Potze, J. H.; Irwan, R.; Oudkerk, M.

    2006-01-01

    Quantitative brain MR spectroscopy (MRS) and diffusion tensor imaging (DTI) were used to characterize one patient with Sturge-Weber syndrome. Choline increases and N-acetylaspartate decreases were observed in pathologic frontal gray matter tissue compared to contralateral unaffected brain tissue wit

  4. Characterization of Al2O3-Supported Manganese Oxides by Electron Spin Resonance and Diffuse Reflectance Spectroscopy

    NARCIS (Netherlands)

    Kijlstra, W.S.; Poels, E.K.; Bliek, A.; Weckhuysen, B.M.; Schoonheydt, R.A.

    1996-01-01

    Alumina-supported manganese oxides, used as catalysts for the selective catalytic reduction of NO, were characterized by combined electron spin resonance and diffuse reflectance spectroscopies. Upon impregnation of the acetate precursor solution, the [Mn(H2O)6]^2+ complex interacts strongly with

  5. Characterization of Al2O3-Supported Manganese Oxides by Electron Spin Resonance and Diffuse Reflectance Spectroscopy

    NARCIS (Netherlands)

    Kijlstra, W.S.; Poels, E.K.; Bliek, A.; Weckhuysen, B.M.; Schoonheydt, R.A.

    2001-01-01

    Alumina-supported manganese oxides, used as catalysts for the selective catalytic reduction of NO, were characterized by combined electron spin resonance and diffuse reflectance spectroscopies. Upon impregnation of the acetate precursor solution, the [Mn(H2O)6]^2+ complex interacts strongly with sur

  6. Diffuse-reflectance fourier-transform mid-infrared spectroscopy as a method of characterizing changes in soil organic matter

    Science.gov (United States)

    Diffuse-Reflectance Fourier-Transform Mid-Infrared Spectroscopy (MidIR) can identify the presence of important organic functional groups in soil organic matter (SOM). Soils contain myriad organic and inorganic components that absorb in the MidIR so spectral interpretation needs to be validated in or...

  7. Fluorescence correlation spectroscopy experiments to quantify free diffusion coefficients in reaction-diffusion systems: The case of Ca2 + and its dyes

    Science.gov (United States)

    Sigaut, Lorena; Villarruel, Cecilia; Ponce, María Laura; Ponce Dawson, Silvina

    2017-06-01

    Many cell signaling pathways involve the diffusion of messengers that bind and unbind to and from intracellular components. Quantifying their net transport rate under different conditions then requires having separate estimates of their free diffusion coefficient and binding or unbinding rates. In this paper, we show how performing sets of fluorescence correlation spectroscopy (FCS) experiments under different conditions, it is possible to quantify free diffusion coefficients and on and off rates of reaction-diffusion systems. We develop the theory and present a practical implementation for the case of the universal second messenger, calcium (Ca2 +) and single-wavelength dyes that increase their fluorescence upon Ca2 + binding. We validate the approach with experiments performed in aqueous solutions containing Ca2 + and Fluo4 dextran (both in its high and low affinity versions). Performing FCS experiments with tetramethylrhodamine-dextran in Xenopus laevis oocytes, we infer the corresponding free diffusion coefficients in the cytosol of these cells. Our approach can be extended to other physiologically relevant reaction-diffusion systems to quantify biophysical parameters that determine the dynamics of various variables of interest.

  8. Experimental setup for radon exposure and first diffusion studies using gamma spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Maier, Andreas, E-mail: a.maier@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Beek, Patrick van [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Technical University Darmstadt, Hochschulstraße 6, 64289 Darmstadt (Germany); Hellmund, Johannes [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Durante, Marco [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Technical University Darmstadt, Hochschulstraße 6, 64289 Darmstadt (Germany); Schardt, Dieter; Kraft, Gerhard; Fournier, Claudia [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany)

    2015-11-01

    In order to measure the uptake and diffusion of {sup 222}Rn in biological material, an exposure chamber was constructed where cell cultures, biological tissues and mice can be exposed to {sup 222}Rn-activities similar to therapy conditions. After exposure, the material is transferred to a gamma spectrometer and the decay of {sup 214}Pb and {sup 214}Bi is analyzed. From the time kinetics of these decays the total amount of the initial {sup 222}Rn concentration can be calculated. In this paper the design and construction as well as first test measurements are reported.

  9. Oscillation quenching in third order phase locked loop coupled by mean field diffusive coupling

    Science.gov (United States)

    Chakraborty, S.; Dandapathak, M.; Sarkar, B. C.

    2016-11-01

    We explored analytically the oscillation quenching phenomena (amplitude death and parameter dependent inhomogeneous steady state) in a coupled third order phase locked loop (PLL) both in periodic and chaotic mode. The phase locked loops were coupled through mean field diffusive coupling. The lower and upper limits of the quenched state were identified in the parameter space of the coupled PLL using the Routh-Hurwitz technique. We further observed that the ability of convergence to the quenched state of coupled PLLs depends on the design parameters. For identical systems, both the systems converge to the homogeneous steady state, whereas for non-identical parameter values they converge to an inhomogeneous steady state. It was also observed that for identical systems, the quenched state is wider than the non-identical case. When the system parameters are so chosen that each isolated loop is chaotic in nature, we observe narrowing down of the quenched state. All these phenomena were also demonstrated through numerical simulations.

  10. Active Contour Model Coupling with Higher Order Diffusion for Medical Image Segmentation

    Directory of Open Access Journals (Sweden)

    Guodong Wang

    2014-01-01

    Full Text Available Active contour models are very popular in image segmentation. Different features such as mean gray and variance are selected for different purpose. But for image with intensity inhomogeneities, there are no features for segmentation using the active contour model. The images with intensity inhomogeneities often occurred in real world especially in medical images. To deal with the difficulties raised in image segmentation with intensity inhomogeneities, a new active contour model with higher-order diffusion method is proposed. With the addition of gradient and Laplace information, the active contour model can converge to the edge of the image even with the intensity inhomogeneities. Because of the introduction of Laplace information, the difference scheme becomes more difficult. To enhance the efficiency of the segmentation, the fast Split Bregman algorithm is designed for the segmentation implementation. The performance of our method is demonstrated through numerical experiments of some medical image segmentations with intensity inhomogeneities.

  11. Higher-order Solution of Stochastic Diffusion equation with Nonlinear Losses Using WHEP technique

    KAUST Repository

    El-Beltagy, Mohamed A.

    2014-01-06

    Using Wiener-Hermite expansion with perturbation (WHEP) technique in the solution of the stochastic partial differential equations (SPDEs) has the advantage of converting the problem to a system of deterministic equations that can be solved efficiently using the standard deterministic numerical methods [1]. The Wiener-Hermite expansion is the only known expansion that handles the white/colored noise exactly. The main statistics, such as the mean, covariance, and higher order statistical moments, can be calculated by simple formulae involving only the deterministic Wiener-Hermite coefficients. In this poster, the WHEP technique is used to solve the 2D diffusion equation with nonlinear losses and excited with white noise. The solution will be obtained numerically and will be validated and compared with the analytical solution that can be obtained from any symbolic mathematics package such as Mathematica.

  12. Measuring spin diffusion of electrons in bulk n-GaAs using circularly dichromatic absorption difference spectroscopy of spin gratings

    Science.gov (United States)

    Yu, Hua-Liang; Zhang, Xiu-Min; Wang, Peng-Fei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Lai, Tianshu

    2009-05-01

    Circular dichromatic absorption difference spectroscopy is developed to measure the spin diffusion dynamics of electrons in bulk n-GaAs. This spectroscopy has higher detection sensitivity over homodyne detection of spin-grating-diffracted signal. A model to describe circular dichromatic absorption difference signal is derived and used to fit experimental signal to retrieve decaying rate of spin gratings. A spin diffusion constant of Ds=201±25 cm2/s for bulk n-GaAs has been measured at room temperature using this technique and is close to electron diffusion constant (Dc), which is much different from the case in GaAs quantum wells where Ds is markedly less than Dc.

  13. Nondestructive inspection of organic films on sandblasted metals using diffuse reflectance infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Powell, G.L. [Oak Ridge Y-12 Plant, TN (United States); Cox, R.L. [Oak Ridge National Lab., TN (United States); Barber, T.E. [Sam Houston State Univ., Huntsville, TX (United States); Neu, J.T. [Surface Optics Corp., San Diego, CA (United States)

    1996-07-08

    Diffuse reflectance infrared spectroscopy is a very useful tool for the determination of surface contamination and characterization of films in manufacturing applications. Spectral data from the surfaces of a host of practical materials may be obtained with sufficient insensitivity to characterize relatively thick films, such as paint, and the potential exists to detect very thin films, such as trace oil contamination on metals. The SOC 400 Surface Inspection Machine/InfraRed (SIMIR) has been developed as a nondestructive inspection tool to exploit this potential in practical situations. This SIMIR is a complete and ruggidized Fourier transform infrared spectrometer with a very efficient and robust barrel ellipse diffuse reflectance optical collection system and operating software system. The SIMIR weighs less than 8 Kg, occupies less than 14 L volume, and may be manipulated into any orientation during operation. The surface to be inspected is placed at the focal point of the SIMIR by manipulating the SIMIR or the surface. The SIMIR may or may not contact the surface being inspected. For flat or convex items, there are no size limits to items being inspected. For concave surfaces, the SIMIR geometry limits the surface to those having a radius of curvature greater than 0.2 m. For highly reflective metal surfaces, the SIMIR has a noise level approaching 1 {times} 10{sup {minus}4} absorbance units, which is sufficient for detecting nanometer thick organic film residues on metals. The use of this nondestructive inspection tool is demonstrated by the spatial mapping of organic stains on sand blasted metals in which organic stains such as silicone oils, mineral oils, and triglycerides are identified both qualitatively and quantitatively over the surface of the metal specimen.

  14. Light-induced autofluorescence and diffuse reflectance spectroscopy in clinical diagnosis of skin cancer

    Science.gov (United States)

    Borisova, E.; Pavlova, E.; Kundurjiev, T.; Troyanova, P.; Genova, Ts.; Avramov, L.

    2014-05-01

    We investigated more than 500 clinical cases to receive the spectral properties of basal cell (136 patients) and squamous cell carcinoma (28), malignant melanoma (41) and different cutaneous dysplastic and benign cutaneous lesions. Excitation at 365, 385 and 405 nm using LEDs sources is applied to obtain autofluorescence spectra, and broad-band illumination in the region of 400-900 nm is used to detect diffuse reflectance spectra of all pathologies investigated. USB4000 microspectrometer (Ocean Optics Inc, USA) is applied as a detector and fiber-optic probe is used for delivery of the light. In the case of in vivo tumor measurements spectral shape and intensity changes are observed that are specific for a given type of lesion. Autofluorescence origins of the signals coming from skin tissues are mainly due to proteins, such as collagen, elastin, keratin, their cross-links, co-enzimes - NADH and flavins and endogenous porphyrins. Spectral features significant into diffuse spectroscopy diagnosis are related to the effects of re-absorption of hemoglobin and its forms, as well as melanin and its concentration in different pathologies. We developed significant database and revealed specific features for a large class of cutaneous neoplasia, using about 30 different spectral peculiarities to differentiate cutaneous tumors. Sensitivity and specificity obtained exceed 90%, which make optical biopsy very useful tool for clinical practice. These results are obtained in the frames of clinical investigations for development of significant "spectral features" database for the most common cutaneous malignant, dysplastic and benign lesions. In the forthcoming plans, our group tries to optimize the existing experimental system for optical biopsy of skin, and to introduce it and the diagnostic algorithms developed into clinical practice, based on the high diagnostic accuracy achieved.

  15. A portable device for detecting fruit quality by diffuse reflectance Vis/NIR spectroscopy

    Science.gov (United States)

    Sun, Hongwei; Peng, Yankun; Li, Peng; Wang, Wenxiu

    2017-05-01

    Soluble solid content (SSC) is a major quality parameter to fruit, which has influence on its flavor or texture. Some researches on the on-line non-invasion detection of fruit quality were published. However, consumers desire portable devices currently. This study aimed to develop a portable device for accurate, real-time and nondestructive determination of quality factors of fruit based on diffuse reflectance Vis/NIR spectroscopy (520-950 nm). The hardware of the device consisted of four units: light source unit, spectral acquisition unit, central processing unit, display unit. Halogen lamp was chosen as light source. When working, its hand-held probe was in contact with the surface of fruit samples thus forming dark environment to shield the interferential light outside. Diffuse reflectance light was collected and measured by spectrometer (USB4000). ARM (Advanced RISC Machines), as central processing unit, controlled all parts in device and analyzed spectral data. Liquid Crystal Display (LCD) touch screen was used to interface with users. To validate its reliability and stability, 63 apples were tested in experiment, 47 of which were chosen as calibration set, while others as prediction set. Their SSC reference values were measured by refractometer. At the same time, samples' spectral data acquired by portable device were processed by standard normalized variables (SNV) and Savitzky-Golay filter (S-G) to eliminate the spectra noise. Then partial least squares regression (PLSR) was applied to build prediction models, and the best predictions results was achieved with correlation coefficient (r) of 0.855 and standard error of 0.6033° Brix. The results demonstrated that this device was feasible to quantitatively analyze soluble solid content of apple.

  16. Differentiation of intracranial tuberculomas and high grade gliomas using proton MR spectroscopy and diffusion MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Juan, E-mail: pengjuan1209@126.com [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China); Ouyang, Yu, E-mail: 1957ouyangyu@sina.com [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China); Fang, Wei-Dong, E-mail: fwd9707@yahoo.com.cn [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China); Luo, Tian-You, E-mail: ltychy@sina.com [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China); Li, Yong-Mei, E-mail: lymzhang70@yahoo.com.cn [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China); Lv, Fa-Jin, E-mail: fajinlv@hotmail.com [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China); Zhang, Zhi-Wei, E-mail: jintianzzw@163.com [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China); Li, Xin-You, E-mail: lixinyou666@163.com [Department of Radiology, the First Affiliated Hospital, Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016 (China)

    2012-12-15

    Objective: The purpose of this study was to determine whether proton MR spectroscopy ({sup 1}H MRS) and diffusion-weighted (DW) imaging can be used to differentiate intracranial tuberculomas from high grade gliomas (HGGs). Materials and methods: A total of 41 patients (19 with intracranial tuberculomas and 22 with HGGs) were examined in our study. {sup 1}H MRS and DW imaging were performed at a 1.5T MR scanner before operation or treatment. Concentrations of N-acetylaspartate (NAA), creatine (Cr), choline (Cho), and lipid and lactate (LL) in the contrast-enhancing rim of each lesion were expressed as metabolite ratios and were normalized to the contralateral hemisphere. The apparent diffusion coefficient (ADC) was also calculated. The metabolite ratios and ADC values in the enhancing rim of intracranial tuberculomas and HGGs were compared using the Wilcoxon rank sum test. Diagnostic accuracy was compared using receiver operating characteristic (ROC) analysis. Results: Significant differences were found in the maximum Cho/Cr (P = 0.015), Cho/NAA (P = 0.001) and Cho/Cho-n ratios (P = 0.002), and minimum ADC value (P < 0.001) between the intracranial tuberculomas and HGGs. Diagnostic accuracy was higher by minimum ADC value than maximum Cho/Cr, Cho/NAA and Cho/Cho-n ratios (93.8% versus 75.7%, 80.8% and 78.1%). Conclusion: These results suggest a promising role for {sup 1}H MRS and DW imaging in the differentiation between the intracranial tuberculomas and HGGs.

  17. Monitoring longitudinal changes in irradiated head and neck cancer xenografts using diffuse reflectance spectroscopy

    Science.gov (United States)

    Vishwanath, Karthik; Jiang, Shudong; Gunn, Jason R.; Marra, Kayla; Andreozzi, Jacqueline M.; Pogue, Brian W.

    2016-02-01

    Radiation therapy is often used as the preferred clinical treatment for control of localized head and neck cancer. However, during the course of treatment (6-8 weeks), feedback about functional and/or physiological changes within impacted tissue are not obtained, given the onerous financial and/or logistical burdens of scheduling MRI, PET or CT scans. Diffuse optical sensing is well suited to address this problem since the instrumentation can be made low-cost and portable while still being able to non-invasively provide information about vascular oxygenation in vivo. Here we report results from studies that employed an optical fiber-based portable diffuse reflectance spectroscopy (DRS) system to longitudinally monitor changes in tumor vasculature within two head and neck cancer cell lines (SCC-15 and FaDu) xenografted in the flanks of nude mice, in two separate experiments. Once the tumor volumes were 100mm3, 67% of animals received localized (electron beam) radiation therapy in five fractions (8Gy/day, for 5 days) while 33% of the animals served as controls. DRS measurements were obtained from each animal on each day of treatment and then for two weeks post-treatment. Reflectance spectra were parametrized to extract total hemoglobin concentration and blood oxygen-saturation and the resulting time-trends of optical parameters appear to be dissimilar for the two cell-lines. These findings are also compared to previous animal experiments (using the FaDu line) that were irradiated using a photon beam radiotherapy protocol. These results and implications for the use of fiber-based DRS measurements made at local (irradiated) tumor site as a basis for identifying early radiotherapy-response are presented and discussed.

  18. Quantitative Analysis of Berberine in Processed Coptis by Near-Infrared Diffuse Reflectance Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; XIE Yun-fei; SONG Feng-rui; LIU Zhi-qiang; CONG Qian; ZHAO Bing

    2008-01-01

    The near-infrared(NIR) diffuse reflectance spectroscopy was used to study the content of Berberine in the processed Coptis.The allocated proportions of Coptis to ginger,yellow liquor or Evodia rutaecarpa changed according to the results of orthogonal design as well as the temperature.For as withdrawing the full and effective information from the spectral data as possible,the spectral data was preprocessed through first derivative and muitiplicative scatter correction(MSC) according to the optimization results of different preprocessing methods.Firstly,the model was established by partial least squares(PLS); the coefficient of determination(R2) of the prediction was 0.839,the root mean squared error of prediction(RMSEP) was 0.1422,and the mean relative error(RME) was 0.0276.Secondly,for reducing the dimension and removing noise,the spectral variables were highly effectively compressed via the wavelet transformation(WT) technology and the Haar wavelet was selected to decompose the spectral signals.After the wavelet coefficients from WT were input into the artificial neural network(ANN) instead of the spectra signal,the quantitative analysis model of Berberine in processed Coptis was established.The R2 of the model was 0.9153,the RMSEP was 0.0444,and the RME was 0.0091.The values of appraisal index,namely R2,RMSECV,and RME,indicate that the generalization ability and prediction precision of ANN are superior to those of PLS.The overall results show that NIR spectroscopy combined with ANN can be efficiently utilized for the rapid and accurate analysis of routine chemical compositions in Coptis.Accordingly,the result can provide technical support for the further analysis of Berberine and other components in processed Coptis.Simultaneously,the research can also offer the foundation of quantitative analysis of other NIR application.

  19. Single- and Multivoxel Proton Spectroscopy in Pediatric Patients With Diffuse Intrinsic Pontine Glioma

    Energy Technology Data Exchange (ETDEWEB)

    Steffen-Smith, Emilie A. [Pediatric Oncology Branch, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland (United States); Venzon, David J. [Biostatistics and Data Management Section, National Cancer Institute, National Institutes of Health, Bethesda, Maryland (United States); Bent, Robyn S. [Pediatric Oncology Branch, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland (United States); Hipp, Sean J. [Pediatric Oncology Branch, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland (United States); Department of Pediatrics, Walter Reed National Military Medical Center, Bethesda, Maryland (United States); Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, Maryland (United States); Warren, Katherine E., E-mail: warrenk@mail.nih.gov [Pediatric Oncology Branch, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland (United States)

    2012-11-01

    Purpose: To determine the feasibility of two magnetic resonance spectroscopy (MRS) techniques for treating pediatric patients with diffuse intrinsic pontine gliomas (DIPGs) and to evaluate the relationship of metabolic profiles determined by each technique. Utility of each technique for improving patient management is also discussed. Methods and Materials: Children with DIPG (n = 36) were evaluated using single-voxel spectroscopy (SVS) and magnetic resonance spectroscopic imaging (MRSI) during the same imaging session. Patients were followed longitudinally (n = 150 total studies). Technical feasibility was defined by sufficient water and lipid suppression for detection of metabolites. Correlation of metabolic data obtained by SVS and MRSI was determined using the Spearman rank method. Metabolite ratios, including choline:N-acetyl-aspartate (Cho:NAA) and Cho:creatine (Cho:Cr), were obtained from SVS and MRSI. Results: SVS and MRSI acquisitions were feasible in >90% of studies. Maximum Cho:NAA and Cho:Cr from MRSI analysis were strongly associated with Cho:NAA and Cho:Cr obtained by SVS (r = 0.67 and 0.76, respectively). MRSI Cho:NAA values were more heterogeneous than Cho:Cr values within the same lesion, and a strong linear relationship between the range and maximum Cho:NAA values was observed. Conclusions: SVS and MRSI acquisitions were feasible, with a strong correlation in metabolic data. Both techniques may improve diagnostic evaluation and management of DIPG. SVS is recommended for global assessment of tumor metabolism before and after therapy. MRSI showed heterogeneous patterns of metabolic activity within these tumors and is recommended for planning and monitoring targeted therapies and evaluating nearby tissue for tumor invasion.

  20. Non-invasive assessment of cerebral microcirculation with diffuse optics and coherent hemodynamics spectroscopy

    Science.gov (United States)

    Fantini, Sergio; Sassaroli, Angelo; Kainerstorfer, Jana M.; Tgavalekos, Kristen T.; Zang, Xuan

    2016-03-01

    We describe the general principles and initial results of coherent hemodynamics spectroscopy (CHS), which is a new technique for the quantitative assessment of cerebral hemodynamics on the basis of dynamic near-infrared spectroscopy (NIRS) measurements. The two components of CHS are (1) dynamic measurements of coherent cerebral hemodynamics in the form of oscillations at multiple frequencies (frequency domain) or temporal transients (time domain), and (2) their quantitative analysis with a dynamic mathematical model that relates the concentration and oxygen saturation of hemoglobin in tissue to cerebral blood volume (CBV), cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2). In particular, CHS can provide absolute measurements and dynamic monitoring of CBF, and quantitative measures of cerebral autoregulation. We report initial results of CBF measurements in hemodialysis patients, where we found a lower CBF (54 +/- 16 ml/(100 g-min)) compared to a group of healthy controls (95 +/- 11 ml/(100 g-min)). We also report CHS measurements of cerebral autoregulation, where a quantitative index of autoregulation (its cutoff frequency) was found to be significantly greater in healthy subjects during hyperventilation (0.034 +/- 0.005 Hz) than during normal breathing (0.017 +/- 0.002 Hz). We also present our approach to depth resolved CHS, based on multi-distance, frequency-domain NIRS data and a two-layer diffusion model, to enhance sensitivity to cerebral tissue. CHS offers a potentially powerful approach to the quantitative assessment and continuous monitoring of local brain perfusion at the microcirculation level, with prospective brain mapping capabilities of research and clinical significance.

  1. Direct observation of multistep energy transfer in LHCII with fifth-order 3D electronic spectroscopy

    Science.gov (United States)

    Zhang, Zhengyang; Lambrev, Petar H.; Wells, Kym L.; Garab, Győző; Tan, Howe-Siang

    2015-07-01

    During photosynthesis, sunlight is efficiently captured by light-harvesting complexes, and the excitation energy is then funneled towards the reaction centre. These photosynthetic excitation energy transfer (EET) pathways are complex and proceed in a multistep fashion. Ultrafast two-dimensional electronic spectroscopy (2DES) is an important tool to study EET processes in photosynthetic complexes. However, the multistep EET processes can only be indirectly inferred by correlating different cross peaks from a series of 2DES spectra. Here we directly observe multistep EET processes in LHCII using ultrafast fifth-order three-dimensional electronic spectroscopy (3DES). We measure cross peaks in 3DES spectra of LHCII that directly indicate energy transfer from excitons in the chlorophyll b (Chl b) manifold to the low-energy level chlorophyll a (Chl a) via mid-level Chl a energy states. This new spectroscopic technique allows scientists to move a step towards mapping the complete complex EET processes in photosynthetic systems.

  2. 2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion

    Science.gov (United States)

    Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning

    2016-08-01

    Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility.

  3. Easy measurement of diffusion coefficients of EGFP-tagged plasma membrane proteins using k-space Image Correlation Spectroscopy

    DEFF Research Database (Denmark)

    Christensen, Eva Arnspang; Koffman, Jennifer Skaarup; Marlar, Saw

    2014-01-01

    Lateral diffusion and compartmentalization of plasma membrane proteins are tightly regulated in cells and thus, studying these processes will reveal new insights to plasma membrane protein function and regulation. Recently, k-Space Image Correlation Spectroscopy (kICS)1 was developed to enable...... to the correlation function yields the diffusion coefficient. This paper provides a step-by-step guide to the image analysis and measurement of diffusion coefficients via kICS. First, a high frame rate image sequence of a fluorescently labeled plasma membrane protein is acquired using a fluorescence microscope Then...... routine measurements of diffusion coefficients directly from images of fluorescently tagged plasma membrane proteins, that avoided systematic biases introduced by probe photophysics. Although the theoretical basis for the analysis is complex, the method can be implemented by nonexperts using a freely...

  4. Feasibility of diffuse reflectance infrared Fourier spectroscopy (DRIFTS) to quantify iron-cyanide (Fe-CN) complexes in soil

    Science.gov (United States)

    Sut-Lohmann, Magdalena; Raab, Thomas

    2017-04-01

    Contaminated sites create a significant risk to human health, by poisoning drinking water, soil, air and as a consequence food. Continuous release of persistent iron-cyanide (Fe-CN) complexes from various industrial sources poses a high hazard to the environment and indicates the necessity to analyze considerable amount of samples. At the present time quantitative determination of Fe-CN concentration in soil usually requires a time consuming two step process: digestion of the sample (e.g., micro distillation system) and its analytical detection performed, e.g., by automated spectrophotometrical flow injection analysis (FIA). In order to determine the feasibility of diffuse reflectance infrared Fourier spectroscopy (DRIFTS) to quantify the Fe-CN complexes in soil matrix, 42 soil samples were collected (8 to 12.520 mg kg-1CN) indicating single symmetrical CN band in the range 2092 - 2084 cm-1. Partial least squares (PLS) calibration-validation model revealed IR response to CNtot exceeding 1268 mg kg-1 (limit of detection, LOD). Subsequently, leave-one-out cross-validation (LOO-CV) was performed on soil samples containing low CNtot (900 mg kg-1 resulted in LOD equal to 3494 mg kg-1. Our results indicate that spectroscopic data in combination with PLS statistics can efficiently be used to predict Fe-CN concentrations in soil. We conclude that the protocol applied in this study can strongly reduce the time and costs essential for the spatial and vertical screening of the site affected by complexed Fe-CN.

  5. Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy

    Science.gov (United States)

    Seong, Myeongsu; Phillips, Zephaniah; Mai, Phuong Minh; Yeo, Chaebeom; Song, Cheol; Lee, Kijoon; Kim, Jae Gwan

    2016-02-01

    A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements. In order to validate the system, a flow phantom test and an arm occlusion protocol for arterial and venous occlusion were performed. Shorter exposure times (<1 ms) show a higher drop (between 50% and 66%) and recovery of 1/KS2 values after occlusion (approximately 150%), but longer exposure time (3 ms) shows more consistent hemodynamic changes. For four subjects, the 1/KS2 values dropped to an average of 82.1±4.0% during the occlusion period and the average recovery of 1/KS2 values after occlusion was 109.1±0.8%. There was also an approximately equivalent amplitude change in oxyhemoglobin (OHb) and deoxyhemoglobin (RHb) during arterial occlusion (max RHb=0.0085±0.0024 mM/DPF, min OHb=-0.0057±0.0044 mM/DPF). The sensitivity of the system makes it a suitable modality to observe qualitative hemodynamic trends during induced physiological changes.

  6. Axi-symmetric generalized thermoelastic diffusion problem with two-temperature and initial stress under fractional order heat conduction

    Science.gov (United States)

    Deswal, Sunita; Kalkal, Kapil Kumar; Sheoran, Sandeep Singh

    2016-09-01

    A mathematical model of fractional order two-temperature generalized thermoelasticity with diffusion and initial stress is proposed to analyze the transient wave phenomenon in an infinite thermoelastic half-space. The governing equations are derived in cylindrical coordinates for a two dimensional axi-symmetric problem. The analytical solution is procured by employing the Laplace and Hankel transforms for time and space variables respectively. The solutions are investigated in detail for a time dependent heat source. By using numerical inversion method of integral transforms, we obtain the solutions for displacement, stress, temperature and diffusion fields in physical domain. Computations are carried out for copper material and displayed graphically. The effect of fractional order parameter, two-temperature parameter, diffusion, initial stress and time on the different thermoelastic and diffusion fields is analyzed on the basis of analytical and numerical results. Some special cases have also been deduced from the present investigation.

  7. Diffuse reflectance spectroscopy and optical polarization imaging of in-vivo biological tissue

    Science.gov (United States)

    Mora-Núñez, A.; Castillejos, Y.; García-Torales, G.; Martínez-Ponce, G.

    2013-11-01

    A number of optical techniques have been reported in the scientific literature as accomplishable methodologies to diagnose diseases in biological tissue, for instance, diffuse reflectance spectroscopy (DRS) and optical polarization imaging (OPI). The skin is the largest organ in the body and consists of three primary layers, namely, the epidermis (the outermost layer exposed to the world), the dermis, and the hypodermis. The epidermis changes from to site to site, mainly because of difference in hydration. A lower water content increase light scattering and reduce the penetration depth of radiation. In this work, two hairless mice have been selected to evaluate their skin features by using DRS and OPI. Four areas of the specimen body were chosen to realize the comparison: back, abdomen, tail, and head. From DRS, it was possible to distinguish the skin nature because of different blood irrigation at dermis. In the other hand, OPI shows pseudo-depolarizing regions in the measured Mueller images related to a spatially varying propagation of the scattered light. This provides information about the cell size in the irradiated skin.

  8. Decreased microvascular cerebral blood flow assessed by diffuse correlation spectroscopy after repetitive concussions in mice.

    Science.gov (United States)

    Buckley, Erin M; Miller, Benjamin F; Golinski, Julianne M; Sadeghian, Homa; McAllister, Lauren M; Vangel, Mark; Ayata, Cenk; Meehan, William P; Franceschini, Maria Angela; Whalen, Michael J

    2015-12-01

    Repetitive concussions are associated with long-term cognitive dysfunction that can be attenuated by increasing the time intervals between concussions; however, biomarkers of the safest rest interval between injuries remain undefined. We hypothesize that deranged cerebral blood flow (CBF) is a candidate biomarker for vulnerability to repetitive concussions. Using a mouse model of human concussion, we examined the effect of single and repetitive concussions on cognition and on an index of CBF (CBFi) measured with diffuse correlation spectroscopy. After a single mild concussion, CBFi was reduced by 35±4% at 4 hours (Pconcussions spaced 1 day apart, CBFi was also reduced from preinjury levels 4 hours after each concussion but had returned to preinjury levels by 72 hours after the final concussion. Interestingly, in this repetitive concussion model, lower CBFi values measured both preinjury and 4 hours after the third concussion were associated with worse performance on the Morris water maze assessed 72 hours after the final concussion. We conclude that low CBFi measured either before or early on in the evolution of injury caused by repetitive concussions could be a useful predictor of cognitive outcome.

  9. Detection of canine skin and subcutaneous tumors by visible and near-infrared diffuse reflectance spectroscopy

    Science.gov (United States)

    Cugmas, Blaž; Plavec, Tanja; Bregar, Maksimilijan; Naglič, Peter; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

    2015-03-01

    Cancer is the main cause of canine morbidity and mortality. The existing evaluation of tumors requires an experienced veterinarian and usually includes invasive procedures (e.g., fine-needle aspiration) that can be unpleasant for the dog and the owner. We investigate visible and near-infrared diffuse reflectance spectroscopy (DRS) as a noninvasive optical technique for evaluation and detection of canine skin and subcutaneous tumors ex vivo and in vivo. The optical properties of tumors and skin were calculated in a spectrally constrained manner, using a lookup table-based inverse model. The obtained optical properties were analyzed and compared among different tumor groups. The calculated parameters of the absorption and reduced scattering coefficients were subsequently used for detection of malignant skin and subcutaneous tumors. The detection sensitivity and specificity of malignant tumors ex vivo were 90.0% and 73.5%, respectively, while corresponding detection sensitivity and specificity of malignant tumors in vivo were 88.4% and 54.6%, respectively. The obtained results show that the DRS is a promising noninvasive optical technique for detection and classification of malignant and benign canine skin and subcutaneous tumors. The method should be further investigated on tumors with common origin.

  10. Simultaneous Determination of Amiloride and Hydrochlorothiazide in a Compound Tablet by Diffuse Reflectance Spectroscopy and Chemometrics

    Science.gov (United States)

    Tang, J.; Li, X.; Feng, Y.; Liang, B.

    2016-09-01

    This paper studies the simultaneous determination of amiloride hydrochloride (AMH) and hydrochlorothiazide (HCTZ) in amiloride hydrochloride tablets by ultraviolet-visible-shortwave near-infrared diffuse reflectance spectroscopy (UV-Vis-swNIR DRS) and chemometrics. Quantitative models for the two components were established by partial least squares (PLS) and support vector regression (SVR), respectively. For the PLS models of AMH and HCTZ, the determination coefficient R2 of the calibration set was 0.9503 and 0.9538, and the coefficient R2 of the prediction set was 0.8983 and 0.9260, respectively. The root mean square error of the calibration set (RMSEC) was 0.8 mg and 8.1 mg, while the root mean square error of the prediction set (RMSEP) was 1.0 mg and 8.7 mg, respectively. For the SVR models of AMH and HCTZ, the R2 of the calibration set was 0.9668 and 0.9609; the R2 of the prediction set was 0.9145 and 0.9446, respectively. The RMSEC was 0.7 and 7.5 mg, and the RMSEP was 0.9 and 8.9 mg, respectively. The results show that SVR modeling has a satisfactory prediction effect. The proposed method based on UV-vis-swNIR and chemometrics is efficient, nondestructive, and expected to be used for online quality monitoring in the production of drugs.

  11. Noninvasive optical cytochrome c oxidase redox state measurements using diffuse optical spectroscopy

    Science.gov (United States)

    Lee, Jangwoen; Kim, Jae G.; Mahon, Sari B.; Mukai, David; Yoon, David; Boss, Gerry R.; Patterson, Steven E.; Rockwood, Gary; Isom, Gary; Brenner, Matthew

    2014-05-01

    A major need exists for methods to assess organ oxidative metabolic states in vivo. By contrasting the responses to cyanide (CN) poisoning versus hemorrhage in animal models, we demonstrate that diffuse optical spectroscopy (DOS) can detect cytochrome c oxidase (CcO) redox states. Intermittent decreases in inspired O2 from 100% to 21% were applied before, during, and after CN poisoning, hemorrhage, and resuscitation in rabbits. Continuous DOS measurements of total hemoglobin, oxyhemoglobin, deoxyhemoglobin, and oxidized and reduced CcO from muscle were obtained. Rabbit hemorrhage was accomplished with stepwise removal of blood, followed by blood resuscitation. CN treated rabbits received 0.166 mg/min NaCN infusion. During hemorrhage, CcO redox state became reduced concurrently with decreases in oxyhemoglobin, resulting from reduced tissue oxygen delivery and hypoxia. In contrast, during CN infusion, CcO redox state decreased while oxyhemoglobin concentration increased due to CN binding and reduction of CcO with resultant inhibition of the electron transport chain. Spectral absorption similarities between hemoglobin and CcO make noninvasive spectroscopic distinction of CcO redox states difficult. By contrasting physiological perturbations of CN poisoning versus hemorrhage, we demonstrate that DOS measured CcO redox state changes are decoupled from hemoglobin concentration measurement changes.

  12. Quantitative skin color measurements in acanthosis nigricans patients: colorimetry and diffuse reflectance spectroscopy.

    Science.gov (United States)

    Pattamadilok, Bensachee; Devpura, Suneetha; Syed, Zain U; Agbai, Oma N; Vemulapalli, Pranita; Henderson, Marsha; Rehse, Steven J; Mahmoud, Bassel H; Lim, Henry W; Naik, Ratna; Hamzavi, Iltefat H

    2012-08-01

    Tristimulus colorimetry and diffuse reflectance spectroscopy (DRS) are white-light skin reflectance techniques used to measure the intensity of skin pigmentation. The tristimulus colorimeter is an instrument that measures a perceived color and the DRS instrument measures biological chromophores of the skin, including oxy- and deoxyhemoglobin, melanin and scattering. Data gathered from these tools can be used to understand morphological changes induced in skin chromophores due to conditions of the skin or their treatments. The purpose of this study was to evaluate the use of these two instruments in color measurements of acanthosis nigricans (AN) lesions. Eight patients with hyperinsulinemia and clinically diagnosable AN were seen monthly. Skin pigmentation was measured at three sites: the inner forearm, the medial aspect of the posterior neck, and anterior neck unaffected by AN. Of the three, measured tristimulus L*a*b* color parameters, the luminosity parameter L* was found to most reliably distinguish lesion from normally pigmented skin. The DRS instrument was able to characterize a lesion on the basis of the calculated melanin concentration, though melanin is a weak indicator of skin change and not a reliable measure to be used independently. Calculated oxyhemoglobin and deoxyhemoglobin concentrations were not found to be reliable indicators of AN. Tristimulus colorimetry may provide reliable methods for respectively quantifying and characterizing the objective color change in AN, while DRS may be useful in characterizing changes in skin melanin content associated with this skin condition.

  13. Blood flow measurement of human skeletal muscle during various exercise intensity using diffuse correlation spectroscopy (DCS)

    Science.gov (United States)

    Murakami, Yuya; Ono, Yumie; Ichinose, Masashi

    2017-02-01

    We studied blood flow dynamics of active skeletal muscle using diffuse correlation spectroscopy (DCS), an emerging optical modality that is suitable for noninvasive quantification of microcirculation level in deep tissue. Seven healthy subjects conducted 0.5 Hz dynamic handgrip exercise for 3 minutes at intensities of 10, 20, 30, and 50 % of maximal voluntary contraction (MVC). DCS could detect the time-dependent increase of the blood flow response of the forearm muscle for continuous exercises, and the increase ratios of the mean blood flow through the exercise periods showed good correlation with the exercise intensities. We also compared blood flow responses detected from DCS with two different photon sampling rates and found that an appropriate photon sampling rates should be selected to follow the wide-ranged increase in the muscle blood flow with dynamic exercise. Our results demonstrate the possibility for utilizing DCS in a field of sports medicine to noninvasively evaluate the dynamics of blood flow in the active muscles.

  14. Investigation of calcium aluminates by IR spectroscopy in diffusely scattered light

    Energy Technology Data Exchange (ETDEWEB)

    Medin, A.S.; Borovkov, V.Yu.; Nissenbaum, V.D.; Yakerson, V.I.; Kazanskii, V.B.

    1989-01-01

    The hydroxyl covering and the adsorption sites for CO and H/sub 2/O on aluminum-calcium catalysts and supports with developed surfaces have been studied by IR spectroscopy in diffusely scattered light. The presence of several types of surface OH groups, viz., terminal groups bonded to calcium ions with different types of coordination, bridging OH groups, and groups appearing in (CaOH)/sup +/ groupings, which perform the role of compensating cations in the zeolite-like structure of calcium aluminates, has been established. The shifts of the bands of the OH groups upon the adsorption of C/sub 6/H/sub 6/ and cyclo-C/sub 6/H/sub 12/ point out their weakly acidic or basic character. When calcium aluminates are dehydroxylated, aprotic sites appear on their surfaces, and the rehydration of such surfaces is accompanied by the formation of OH groups and the weakening of the Al-O-M bonds (M = Al, Ca) with the appearance of additional sites for the strong adsorption of water.

  15. Non-invasive tissue temperature measurements based on quantitative diffuse optical spectroscopy (DOS) of water

    Energy Technology Data Exchange (ETDEWEB)

    Chung, S H [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Cerussi, A E; Tromberg, B J [Beckman Laser Institute and Medical Clinic, University of California, Irvine, 1002 Health Sciences Road, Irvine 92612, CA (United States); Merritt, S I [Masimo Corporation, 40 Parker, Irvine, CA 92618 (United States); Ruth, J, E-mail: bjtrombe@uci.ed [Department of Bioengineering, University of Pennsylvania, 210 S. 33rd Street, Room 240, Skirkanich Hall, Philadelphia, PA 19104 (United States)

    2010-07-07

    We describe the development of a non-invasive method for quantitative tissue temperature measurements using Broadband diffuse optical spectroscopy (DOS). Our approach is based on well-characterized opposing shifts in near-infrared (NIR) water absorption spectra that appear with temperature and macromolecular binding state. Unlike conventional reflectance methods, DOS is used to generate scattering-corrected tissue water absorption spectra. This allows us to separate the macromolecular bound water contribution from the thermally induced spectral shift using the temperature isosbestic point at 996 nm. The method was validated in intralipid tissue phantoms by correlating DOS with thermistor measurements (R = 0.96) with a difference of 1.1 {+-} 0.91 {sup 0}C over a range of 28-48 {sup 0}C. Once validated, thermal and hemodynamic (i.e. oxy- and deoxy-hemoglobin concentration) changes were measured simultaneously and continuously in human subjects (forearm) during mild cold stress. DOS-measured arm temperatures were consistent with previously reported invasive deep tissue temperature studies. These results suggest that DOS can be used for non-invasive, co-registered measurements of absolute temperature and hemoglobin parameters in thick tissues, a potentially important approach for optimizing thermal diagnostics and therapeutics.

  16. Inverse Monte Carlo in a multilayered tissue model: merging diffuse reflectance spectroscopy and laser Doppler flowmetry

    Science.gov (United States)

    Fredriksson, Ingemar; Burdakov, Oleg; Larsson, Marcus; Strömberg, Tomas

    2013-12-01

    The tissue fraction of red blood cells (RBCs) and their oxygenation and speed-resolved perfusion are estimated in absolute units by combining diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF). The DRS spectra (450 to 850 nm) are assessed at two source-detector separations (0.4 and 1.2 mm), allowing for a relative calibration routine, whereas LDF spectra are assessed at 1.2 mm in the same fiber-optic probe. Data are analyzed using nonlinear optimization in an inverse Monte Carlo technique by applying an adaptive multilayered tissue model based on geometrical, scattering, and absorbing properties, as well as RBC flow-speed information. Simulations of 250 tissue-like models including up to 2000 individual blood vessels were used to evaluate the method. The absolute root mean square (RMS) deviation between estimated and true oxygenation was 4.1 percentage units, whereas the relative RMS deviations for the RBC tissue fraction and perfusion were 19% and 23%, respectively. Examples of in vivo measurements on forearm and foot during common provocations are presented. The method offers several advantages such as simultaneous quantification of RBC tissue fraction and oxygenation and perfusion from the same, predictable, sampling volume. The perfusion estimate is speed resolved, absolute (% RBC×mm/s), and more accurate due to the combination with DRS.

  17. X-ray spectroscopy with a multi-anode sawtooth silicon drift detector the diffusion process

    CERN Document Server

    Sonsky, J; Sarro, P M; Eijk, C W

    2002-01-01

    The position sensitive detection of low-energy X-rays can be realized by means of a multi-anode linear silicon drift detector (SDD). However, a severe worsening of the spectroscopic quality of the detector is observed due to the lateral broadening of the X-ray generated electron cloud during drift. Recently, we have proved experimentally that electron confinement can be achieved by means of sawtooth-shaped p sup + strips; the sawtooth concept. This paper will present room temperature X-ray spectroscopy measurements clearly demonstrating the improvement of spectroscopic quality of the sawtooth SDD as compared with a traditional linear SDD. Using a sawtooth SDD we have measured an energy resolution of 1.4 keV FWHM at the 13.9 keV peak of sup 2 sup 4 sup 1 Am at room temperature and a substantial reduction of the number of split events is also observed. The calculation of the influence of diffusion on the quality of the pulse height spectrum will also be given.

  18. Heroin-induced leukoencephalopathy: characterization using MRI, diffusion-weighted imaging, and MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Offiah, C. [Department of Neuroradiology, St Bartholomew' s and the London Hospitals NHS Trust, London (United Kingdom); Hall, E. [Department of Neuroradiology, St Bartholomew' s and the London Hospitals NHS Trust, London (United Kingdom)], E-mail: curtis.offiah@bartsandthelondon.nhs.uk

    2008-02-15

    Aim: To describe the magnetic resonance imaging (MRI) characteristics of heroin-induced leukoencephalopathy or 'chasing the dragon syndrome' and, in particular, the diffusion-weighted imaging (DWI) and MR spectroscopy (MRS) features. Material and methods: Six patients with a clinical or histopathological diagnosis of heroin-induced leukoencephalopathy were identified and MRI examinations, including DWI and single-voxel MRS, reviewed. Results: Cerebellar white matter was involved in all six cases demonstrating similar symmetrical distribution with sparing of the dentate nuclei. Brain stem signal change was evident in five of the six patients imaged. Supratentorial brain parenchymal involvement, as well as brain stem involvement, correlated anatomically with corticospinal tract distribution. None of the areas of signal abnormality were restricted on DWI. Of those patients subjected to MRS, the areas of parenchymal damage demonstrated reduced N-acetylaspartate, reduced choline, and elevated lactate. Conclusion: Heroin-induced leukoencephalopathy results in characteristic and highly specific signal abnormalities on MRI, which can greatly aid diagnosis. DWI and MRS findings can be explained by known reported neuropathological descriptions in this condition and can be used to support a proposed mechanism for the benefit of current recommended drug treatment regimes.

  19. Diffuse Optical Spectroscopy and Imaging to Detect and Quantify Adipose Tissue Browning

    Science.gov (United States)

    Dinish, U. S; Wong, Chi Lok; Sriram, Sandhya; Ong, Wee Kiat; Balasundaram, Ghayathri; Sugii, Shigeki; Olivo, Malini

    2017-01-01

    Adipose (fat) tissue is a complex metabolic organ that is highly active and essential. In contrast to white adipose tissue (WAT), brown adipose tissue (BAT) is deemed metabolically beneficial because of its ability to burn calories through heat production. The conversion of WAT-resident adipocytes to “beige” or “brown-like” adipocytes has recently attracted attention. However, it typically takes a few days to analyze and confirm this browning of WAT through conventional molecular, biochemical, or histological methods. Moreover, accurate quantification of the overall browning process is not possible by any of these methods. In this context, we report the novel application of diffuse reflectance spectroscopy (DRS) and multispectral imaging (MSI) to detect and quantify the browning process in mice. We successfully demonstrated the time-dependent increase in browning of WAT, following its induction through β-adrenergic agonist injections. The results from these optical techniques were confirmed with those of standard molecular and biochemical assays, which measure gene and protein expression levels of UCP1 and PGC-1α, as well as with histological examinations. We envision that the reported optical methods can be developed into a fast, real time, cost effective and easy to implement imaging approach for quantification of the browning process in adipose tissue. PMID:28145475

  20. Introducing diffusing wave spectroscopy as a process analytical tool for pharmaceutical emulsion manufacturing.

    Science.gov (United States)

    Reufer, Mathias; Machado, Alexandra H E; Niederquell, Andreas; Bohnenblust, Katharina; Müller, Beat; Völker, Andreas Charles; Kuentz, Martin

    2014-12-01

    Emulsions are widely used for pharmaceutical, food, and cosmetic applications. To guarantee that their critical quality attributes meet specifications, it is desirable to monitor the emulsion manufacturing process. However, finding of a suitable process analyzer has so far remained challenging. This article introduces diffusing wave spectroscopy (DWS) as an at-line technique to follow the manufacturing process of a model oil-in-water pharmaceutical emulsion containing xanthan gum. The DWS results were complemented with mechanical rheology, microscopy analysis, and stability tests. DWS is an advanced light scattering technique that assesses the microrheology and in general provides information on the dynamics and statics of dispersions. The obtained microrheology results showed good agreement with those obtained with bulk rheology. Although no notable changes in the rheological behavior of the model emulsions were observed during homogenization, the intensity correlation function provided qualitative information on the evolution of the emulsion dynamics. These data together with static measurements of the transport mean free path (l*) correlated very well with the changes in droplet size distribution occurring during the emulsion homogenization. This study shows that DWS is a promising process analytical technology tool for development and manufacturing of pharmaceutical emulsions. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  1. Cerebral monitoring during carotid endarterectomy using near-infrared diffuse optical spectroscopies and electroencephalogram

    Energy Technology Data Exchange (ETDEWEB)

    Shang Yu; Cheng Ran; Dong Lixin; Yu Guoqiang [Center for Biomedical Engineering, University of Kentucky, KY (United States); Ryan, Stephen J [Department of Neurology, University of Kentucky, KY (United States); Saha, Sibu P, E-mail: guoqiang.yu@uky.edu [Division of Cardiothoracic Surgery, University of Kentucky, KY (United States)

    2011-05-21

    Intraoperative monitoring of cerebral hemodynamics during carotid endarterectomy (CEA) provides essential information for detecting cerebral hypoperfusion induced by temporary internal carotid artery (ICA) clamping and post-CEA hyperperfusion syndrome. This study tests the feasibility and sensitivity of a novel dual-wavelength near-infrared diffuse correlation spectroscopy technique in detecting cerebral blood flow (CBF) and cerebral oxygenation in patients undergoing CEA. Two fiber-optic probes were taped on both sides of the forehead for cerebral hemodynamic measurements, and the instantaneous decreases in CBF and electroencephalogram (EEG) alpha-band power during ICA clamping were compared to test the measurement sensitivities of the two techniques. The ICA clamps resulted in significant CBF decreases (-24.7 {+-} 7.3%) accompanied with cerebral deoxygenation at the surgical sides (n = 12). The post-CEA CBF were significantly higher (+43.2 {+-} 16.9%) than the pre-CEA CBF. The CBF responses to ICA clamping were significantly faster, larger and more sensitive than EEG responses. Simultaneous monitoring of CBF, cerebral oxygenation and EEG power provides a comprehensive evaluation of cerebral physiological status, thus showing potential for the adoption of acute interventions (e.g., shunting, medications) during CEA to reduce the risks of severe cerebral ischemia and cerebral hyperperfusion syndrome.

  2. Prediction of post-operative necrosis after mastectomy: A pilot study utilizing optical diffusion imaging spectroscopy

    Directory of Open Access Journals (Sweden)

    Xie Xian-Jin

    2009-11-01

    Full Text Available Abstract Introduction Flap necrosis and epidermolysis occurs in 18-30% of all mastectomies. Complications may be prevented by intra-operative detection of ischemia. Currently, no technique enables quantitative valuation of mastectomy skin perfusion. Optical Diffusion Imaging Spectroscopy (ViOptix T.Ox Tissue Oximeter measures the ratio of oxyhemoglobin to deoxyhemoglobin over a 1 × 1 cm area to obtain a non-invasive measurement of perfusion (StO2. Methods This study evaluates the ability of ViOptix T.Ox Tissue Oximeter to predict mastectomy flap necrosis. StO2 measurements were taken at five points before and at completion of dissection in 10 patients. Data collected included: demographics, tumor size, flap length/thickness, co-morbidities, procedure length, and wound complications. Results One patient experienced mastectomy skin flap necrosis. Five patients underwent immediate reconstruction, including the patient with necrosis. Statistically significant factors contributing to necrosis included reduction in medial flap StO2 (p = 0.0189, reduction in inferior flap StO2 (p = 0.003, and flap length (p = 0.009. Conclusion StO2 reductions may be utilized to identify impaired perfusion in mastectomy skin flaps.

  3. Smartphone spectrometer for non-invasive diffuse reflectance spectroscopy based hemoglobin sensing (Conference Presentation)

    Science.gov (United States)

    Edwards, Perry S.

    2016-10-01

    Fiber-optic based diffuse reflectance spectroscopy (DRS) is shown to be a highly specific and highly sensitive method for non-invasive detection of various cancers (e.g. cervical and oral) as well as many other diseases. Fiber-optic DRS diagnosis relies on non-invasive biomarker detection (e.g. oxy- and deoxy-hemoglobin) and can be done without the need for sophisticated laboratory analysis of samples. Thus, it is highly amenable for clinical adoption especially in resource scarce regions that have limited access to such developed laboratory infrastructure. Despite the demonstrated effectiveness of fiber-optic DRS, such systems remain cost prohibitive in many of these regions, mainly due to the use of bulky and expensive spectrometers. Here, a fiber-optic DRS system is coupled to a smartphone spectrometer and is proposed as a low-cost solution for non-invasive tissue hemoglobin sensing. The performance of the system is assessed by measuring tissue phantoms with varying hemoglobin concentrations. A DRS retrieval algorithm is used to extract hemoglobin parameters from the measurements and determine the accuracy of the system. The results are then compared with those of a previously reported fiber-optic DRS system which is based on a larger more expensive spectrometer system. The preliminary results are encouraging and indicate the potential of the smartphone spectrometer as a viable low-cost option for non-invasive tissue hemoglobin sensing.

  4. Ordering of PCDTBT revealed by time-resolved electron paramagnetic resonance spectroscopy of its triplet excitons.

    Science.gov (United States)

    Biskup, Till; Sommer, Michael; Rein, Stephan; Meyer, Deborah L; Kohlstädt, Markus; Würfel, Uli; Weber, Stefan

    2015-06-22

    Time-resolved electron paramagnetic resonance (TREPR) spectroscopy is shown to be a powerful tool to characterize triplet excitons of conjugated polymers. The resulting spectra are highly sensitive to the orientation of the molecule. In thin films cast on PET film, the molecules' orientation with respect to the surface plane can be determined, providing access to sample morphology on a microscopic scale. Surprisingly, the conjugated polymer investigated here, a promising material for organic photovoltaics, exhibits ordering even in bulk samples. Orientation effects may significantly influence the efficiency of solar cells, thus rendering proper control of sample morphology highly important.

  5. Diffusion behavior of the fluorescent proteins eGFP and Dreiklang in solvents of different viscosity monitored by fluorescence correlation spectroscopy

    Science.gov (United States)

    Junghans, Cornelia; Schmitt, Franz-Josef; Vukojević, Vladana; Friedrich, Thomas

    2016-12-01

    Fluorescence correlation spectroscopy relies on temporal autocorrelation analysis of fluorescence intensity fluctuations that spontaneously arise in systems at equilibrium due to molecular motion and changes of state that cause changes in fluorescence, such as triplet state transition, photoisomerization and other photophysical transformations, to determine the rates of these processes. The stability of a fluorescent molecule against dark state conversion is of particular concern for chromophores intended to be used as reference tags for comparing diffusion processes on multiple time scales. In this work, we analyzed properties of two fluorescent proteins, the photoswitchable Dreiklang and its parental eGFP, in solvents of different viscosity to vary the diffusion time through the observation volume element by several orders of magnitude. In contrast to eGFP, Dreiklang undergoes a dark-state conversion on the time scale of tens to hundreds of microseconds under conditions of intense fluorescence excitation, which results in artificially shortened diffusion times if the diffusional motion through the observation volume is sufficiently slowed down. Such photophysical quenching processes have also been observed in FCS studies on other photoswitchable fluorescent proteins including Citrine, from which Dreiklang was derived by genetic engineering. This property readily explains the discrepancies observed previously between the diffusion times of eGFP- and Dreiklang-labeled plasma membrane protein complexes.

  6. Study of spin-temperature effects using energy-ordered continuum gamma-ray spectroscopy technique

    Energy Technology Data Exchange (ETDEWEB)

    Baktash, C.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McConnell, J.W.; McGowan, F.K.

    1990-01-01

    We have investigated a new continuum {gamma}-ray spectroscopy technique which is based on the detection of all emitted {gamma} rays in a 4{pi} detector system, and ordering them according to their energies on an event-by-event basis. The technique allows determination of gamma strength functions, and rotational damping width as a function of spin and temperature. Thus, it opens up the possibility of studying the onset of motional narrowing, order-to-chaos transition, and the mapping of the evolution of nuclear collectivity with a spin and temperature. Application of the technique for preferential entry-state population, exit-channel selection, and feeding of the discrete states via selective pathways will be discussed. 20 refs., 4 figs.

  7. [Determination of isorhamnetin in Hippophae rhamnoides Linn from West Sichuan plateau using near infrared diffuse reflectance spectroscopy].

    Science.gov (United States)

    Ye, Li-Ming; Zhou, Min; Zhang, Hao; Chen, Chu; Li, Zhang-Wan; Chen, Cong; Wang, Yan-Ping

    2008-02-01

    The objective of this study was to develop a method for the determination of isorhamnetin in Hippophae rhamnoides Linn from West Sichuan plateau using near infrared diffuse reflectance spectroscopy. Applying the method of mixing with SiO2, the near infrared spectra (NIS) with the range of 12 000-4 000 cm(-1) were recorded for the Hippophae rhamnoides Linn containing isorhamnetin with the content of 0.1%-0.8%. Calibration models were established using the PLS (partial least squares). Different spectra pretreatments methods were compared. The study showed that spectral information can be extracted thoroughly by constant offset elimination (COE) pretreatments method with the correlation coefficient (r2) of 0.739 8, SEC of 0.107 (standard deviation of the calibration sets) and SEP of 0.073 (standard deviation of the prediction sets). The results indicate that near infrared diffuse reflectance spectroscopy is more rapid and convenient than conventional methods.

  8. Approximate series solution of multi-dimensional, time fractional-order (heat-like) diffusion equations using FRDTM.

    Science.gov (United States)

    Singh, Brajesh K; Srivastava, Vineet K

    2015-04-01

    The main goal of this paper is to present a new approximate series solution of the multi-dimensional (heat-like) diffusion equation with time-fractional derivative in Caputo form using a semi-analytical approach: fractional-order reduced differential transform method (FRDTM). The efficiency of FRDTM is confirmed by considering four test problems of the multi-dimensional time fractional-order diffusion equation. FRDTM is a very efficient, effective and powerful mathematical tool which provides exact or very close approximate solutions for a wide range of real-world problems arising in engineering and natural sciences, modelled in terms of differential equations.

  9. Interstitial diffuse radiance spectroscopy of gold nanocages and nanorods in bulk muscle tissues

    Directory of Open Access Journals (Sweden)

    Grabtchak S

    2015-02-01

    converted to the relative density of photons incident on the inclusion. Finally, the experimentally measured quantities were expressed via the relative perturbation and arranged into the classical Beer–Lambert law that allowed one to extract the extinction coefficients of various types of Au nanoparticles in both the transmission and back reflection geometries. It was shown that the spatial variation of perturbation could be described as 1/r dependence, where r is the distance between the inclusion and the detector. Due to a larger absorption cross section, Au nanocages produced greater perturbations than Au nanorods of equal particle concentration, indicating a better suitability of Au nanocages as contrast agents for optical measurements in turbid media. Individual measurements from different inclusions were combined into detectability maps.Keywords: gold nanocages, gold nanorods, turbid media, porcine muscles, diffuse radiance spectroscopy, Beer–Lambert law, perturbation

  10. Coherent X-ray and laser spectroscopy measurements of diffusion in concentrated alpha-crystallin solutions

    Science.gov (United States)

    Karunaratne, V. N. C.

    The mammalian eye lens is composed of a concentrated solution of water soluble proteins called crystallins. Alpha-crystallin, the most abundant protein found in the lens, plays a crucial role in maintaining lens transparency and lens accommodation. However, alpha-crystallins along with other ocular proteins suffer from irreversible processes such as oxidation. One cause of oxidation is radiation-induced radical formation which alters the inter-molecular interactions, thereby degrading the normal function of ocular proteins. The main goal of this thesis is to quantify molecular scale dynamics of concentrated solutions of alpha-crystallins using coherent X-rays and visible laser light. I believe a detailed analysis of the dynamics pertaining to alpha-crystallin will provide the foundation to understand molecular scale mechanisms that lead to conditions like cataract and presbyopia. I explore the dynamics of concentrated alpha-crystallin solutions by measuring diffusive motion over a range of length scales using Dynamic light scattering (DLS) and X-ray photon correlation spectroscopy (XPCS). To a certain extent, the dynamical properties of crystallins obtained in this manner are consistent with established theories in colloidal physics. However, there are some deviations, which I will address in this thesis. In terms of X-ray data, I employed a new, efficient photon correlation technique to obtain the best possible signal, furthermore this technique is embedded in a stand-alone software program that has the ability to provide real time results, quickly and efficiently with the help of high performance computing resources available at Northern Illinois University (NIU). The technique has potential to be used by the coherent X-ray spectroscopy community in the future. In addition, by using X-ray scattering data, I probe potential modifications and or damage effects on alpha-crystallins due to radiation exposure. The damage analysis methodology described in this thesis

  11. Quantification of joint inflammation in rheumatoid arthritis by time-resolved diffuse optical spectroscopy and tracer kinetic modeling

    Science.gov (United States)

    Ioussoufovitch, Seva; Morrison, Laura B.; Lee, Ting-Yim; St. Lawrence, Keith; Diop, Mamadou

    2015-03-01

    Rheumatoid arthritis (RA) is characterized by chronic synovial inflammation, which can cause progressive joint damage and disability. Diffuse optical spectroscopy (DOS) and imaging have the potential to become potent monitoring tools for RA. We devised a method that combined time-resolved DOS and tracer kinetics modeling to rapidly and reliably quantify blood flow in the joint. Preliminary results obtained from two animals show that the technique can detect joint inflammation as early as 5 days after onset.

  12. The Effect of a Fluorophore Photo-Physics on the Lipid Vesicle Diffusion Coefficient Studied by Fluorescence Correlation Spectroscopy.

    Science.gov (United States)

    Drabik, Dominik; Przybyło, Magda; Sikorski, Aleksander; Langner, Marek

    2016-03-01

    Fluorescence Correlation Spectroscopy (FCS) is a technique, which allows determination of the diffusion coefficient and concentration of fluorescent objects suspended in the solution. The measured parameter is the fluctuation of the fluorescence signal emitted by diffusing molecules. When 100 nm DOPC vesicles labeled with various fluorescent dyes (Fluorescein-PE, NBD-PE, Atto488 DOPE or βBodipy FL) were measured, different values of diffusion coefficients have been obtained. These diffusion coefficients were different from the expected values measured using the dynamic light scattering method (DLS). The FCS was initially developed for solutions containing small fluorescent molecules therefore the observed inconsistency may result from the nature of vesicle suspension itself. The duration of the fluorescence signal may depend on the following factors: the exposure time of the labeled object to the excitation beam, the photo-physical properties (e.g., stability) of a fluorophore, the theoretical model used for the calculations of the diffusion coefficient and optical properties of the vesicle suspension. The diffusion coefficients determined for differently labeled liposomes show that its dependence on vesicle size and quantity of fluorescent probed used for labeling was significant demonstrating that the fluorescence properties of the fluorophore itself (bleaching and/or blinking) were critical factors for a correct outcome of FCS experiment. The new, based on combined FCS and DLS measurements, method for the determination of the focal volume prove itself to be useful for the evaluation of a fluorescence dye with respect to its applicability for FCS experiment.

  13. Diffusion tensor imaging and proton magnetic resonance spectroscopy in brain tumorCorrelation between structure and metabolism

    Institute of Scientific and Technical Information of China (English)

    Zhigang Min; Chen Niu; Netra Rana; Huanmei Ji; Ming Zhang

    2013-01-01

    Proton magnetic resonance spectroscopy and diffusion tensor imaging are non-invasive techniques used to detect metabolites and water diffusion in vivo. Previous studies have confirmed a positive correlation of individual fractional anisotropy values with N-acetylaspartate/creatine and N-acetylaspartate/choline ratios in tumors, edema, and normal white matter. This study divided the brain parenchyma into tumor, peritumoral edema, and normal-appearing white matter according to MRI data, and analyzed the correlation of metabolites with water molecular diffusion. Results demonstrated that in normal-appearing white matter, N-acetylaspartate/creatine ratios were positively correlated with fractional anisotropy values, negatively correlated with radial diffusivities, and positively correlated with maximum eigenvalues. Maximum eigenvalues and radial diffusivities in peritumoral edema showed a negative correlation with choline, N-acetylaspartate, and creatine. Radial diffusivities in tumor demonstrated a negative correlation with choline. These data suggest that the relationship between metabolism and structure is markedly changed from normal white matter to peritumoral edema and tumor. Neural metabolism in the peritumoral edema area decreased with expanding extracellular space. The normal relationship of neural function and microstructure disappeared in the tumor region.

  14. Clinical applications of high-speed blood flow measurements with diffuse correlation spectroscopy

    Science.gov (United States)

    Parthasarathy, Ashwin B.; Baker, Wesley B.; Gannon, Kimberly; Mullen, Michael T.; Detre, John A.; Yodh, Arjun G.

    2017-02-01

    Diffuse Correlation Spectroscopy (DCS) is an increasingly popular non-invasive optical technique to clinically measure deep tissue blood flow, albeit at slow measurement rates of 0.5-1 Hz. We recently reported the development of a new `fast' DCS instrument that continuously measures blood flow at 50-100 Hz (simultaneously from 8 channels), using conventional DCS sources/detectors, and optimized software computations. A particularly interesting result was our ability to optically record pulsatile micro-vascular blood flow waveforms, and therein readily identify high frequency features such as the dicrotic notch. Here, we showcase the utility and potential of high-speed measurements of blood flow (and arterial blood pressure) in a few clinical applications. First, we employ the fast-DCS instrumentation to measure cerebral autoregulation (CVAR) dynamics. Cerebral autoregulation refers to the mechanism by which cerebral blood flow (CBF) is maintained during fluctuations in blood pressure; CVAR is impaired in the injured brain. We derive an index of autoregulation by measuring the rates of decrease (and recovery) of blood flow and blood pressure following a sudden, induced change in systemic blood pressure (e.g., bilateral thigh cuff deflation). Our pilot experiments in healthy volunteers show that DCS measured rates of micro-vascular regulation are comparable to conventional large vessel regulatory metrics (e.g., measured with transcranial Doppler ultrasound). Second, we utilized pulsatile blood flow oscillations in cerebral arteries to estimate the critical closing pressure (CrCP), i.e., the arterial blood pressure at which CBF approaches zero. Pilot experiments in healthy subjects show good agreement between CrCP measured with DCS and transcranial Doppler ultrasound.

  15. Fast diffuse correlation spectroscopy (DCS) for non-invasive measurement of intracranial pressure (ICP) (Conference Presentation)

    Science.gov (United States)

    Farzam, Parisa; Sutin, Jason; Wu, Kuan-Cheng; Zimmermann, Bernhard B.; Tamborini, Davide; Dubb, Jay; Boas, David A.; Franceschini, Maria Angela

    2017-02-01

    Intracranial pressure (ICP) monitoring has a key role in the management of neurosurgical and neurological injuries. Currently, the standard clinical monitoring of ICP requires an invasive transducer into the parenchymal tissue or the brain ventricle, with possibility of complications such as hemorrhage and infection. A non-invasive method for measuring ICP, would be highly preferable, as it would allow clinicians to promptly monitor ICP during transport and allow for monitoring in a larger number of patients. We have introduced diffuse correlation spectroscopy (DCS) as a non-invasive ICP monitor by fast measurement of pulsatile cerebral blood flow (CBF). The method is similar to Transcranial Doppler ultrasound (TCD), which derives ICP from the amplitude of the pulsatile cerebral blood flow velocity, with respect to the amplitude of the pulsatile arterial blood pressure. We believe DCS measurement is superior indicator of ICP than TCD estimation because DCS directly measures blood flow, not blood flow velocity, and the small cortical vessels measured by DCS are more susceptible to transmural pressure changes than the large vessels. For fast DCS measurements to recover pulsatile CBF we have developed a custom high-power long-coherent laser and a strategy for delivering it to the tissue within ANSI standards. We have also developed a custom FPGA-based correlator board, which facilitates DCS data acquisitions at 50-100 Hz. We have tested the feasibility of measuring pulsatile CBF and deriving ICP in two challenging scenarios: humans and rats. SNR is low in human adults due to large optode distances. It is similarly low in rats because the fast heart rate in this setting requires a high repetition rate.

  16. Broadband diffuse optical spectroscopy assessment of hemorrhage- and hemoglobin-based blood substitute resuscitation

    Science.gov (United States)

    Lee, Jangwoen; Kim, Jae G.; Mahon, Sari; Tromberg, Bruce J.; Mukai, David; Kreuter, Kelly; Saltzman, Darin; Patino, Renee; Goldberg, Robert; Brenner, Matthew

    2009-07-01

    Hemoglobin-based oxygen carriers (HBOCs) are solutions of cell-free hemoglobin (Hb) that have been developed for replacement or augmentation of blood transfusion. It is important to monitor in vivo tissue hemoglobin content, total tissue hemoglobin [THb], oxy- and deoxy-hemoglobin concentrations ([OHb], [RHb]), and tissue oxygen saturation (StO2=[OHb]/[THb]×100%) to evaluate effectiveness of HBOC transfusion. We designed and constructed a broadband diffuse optical spectroscopy (DOS) prototype system to measure bulk tissue absorption and scattering spectra between 650 and 1000 nm capable of accurately determining these tissue hemoglobin component concentrations in vivo. Our purpose was to assess the feasibility of using DOS to optically monitor tissue [OHb], [RHb], StO2, and total tissue hemoglobin concentration ([THb]=[OHb]+[RHb]) during HBOC infusion using a rabbit hypovolemic shock model. The DOS prototype probe was placed on the shaved inner thigh muscle of the hind leg to assess concentrations of [OHb], [RHb], [THb], as well as StO2. Hemorrhagic shock was induced in intubated New Zealand white rabbits (N=6) by withdrawing blood via a femoral arterial line to 20% blood loss (10-15 cc/kg). Hemoglobin glutamer-200 (Hb-200) 1:1 volume resuscitation was administered following the hemorrhage. These values were compared against traditional invasive measurements, serum hemoglobin concentration (sHGB), systemic blood pressure, heart rate, and blood gases. DOS revealed increases of [THb], [OHb], and tissue hemoglobin oxygen saturation after Hb-200 infusion, while blood total hemoglobin values continued did not increase; we speculate, due to hyperosmolality induced hemodilution. DOS enables noninvasive in vivo monitoring of tissue hemoglobin and oxygenation parameters during shock and volume expansion with HBOC and potentially enables the assessment of efficacy of resuscitation efforts using artificial blood substitutes.

  17. Diffusivities and atomic mobilities in disordered fcc and ordered L1{sub 2} Ni–Al–W alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chong [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Zhang, Lijun, E-mail: xueyue168@gmail.com [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Xin, Jinghua; Wang, Yaru [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Du, Yong, E-mail: yong-du@csu.edu.cn [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Luo, Fenghua [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Zhang, Zhongjian; Xu, Tao; Long, Jianzhan [State Key Lab of Cemented Carbides, Zhuzhou, Hunan 412000 (China)

    2015-10-05

    Highlights: • The atomic mobilities for fcc Al–W, fcc Ni–W, fcc Ni–Al–W and L1{sub 2} Ni–Al–W alloys were critically assessed. • The impurity diffusivity of W in fcc-Al was obtained via first-principles calculations. • The calculated results agree well with the diffusivities available in the literature. • Two fcc/L1{sub 2}-type diffusion couples were prepared and the concentration-distance profiles were measured. • The model-predicted concentration profiles agree well with the experimental data in the literature and in the present work. - Abstract: Based on various experimentally measured diffusivities available in the literature together with the reported thermodynamic parameters, the atomic mobilities for disordered fcc and ordered L1{sub 2} Ni–Al–W alloys were assessed on the basis of a recently developed phenomenological model incorporated in the DICTRA software. In order to provide the missing impurity diffusion coefficients of W in fcc-Al, first-principles calculations were utilized in the present work. Comprehensive comparisons between the calculated and experimental diffusion coefficients show that all the experimental data can be well reproduced by the atomic mobilities obtained in the present work. In order to further verify the reliability of the presently obtained atomic mobilities, two fcc/L1{sub 2}-type diffusion couples (i.e., Ni–5 at.% Al–5 at.% W/Ni–20 at.% Al–4 at.% W and Ni/Ni–22 at.% Al–2 at.% W) were prepared and the concentration-distance profiles after annealing at 1323 K for 86.4 ks were measured. The excellent agreement between the model-predicted concentration-distance profiles and the experimental data indicates that the presently obtained atomic mobilities in fcc/L1{sub 2} Ni–Al–W alloys are reliable.

  18. Artifact-Free and Detection-Profile-Independent Higher-Order Fluorescence Correlation Spectroscopy for Microsecond-Resolved Kinetics. 1. Multidetector and Sub-Binning Approach.

    Science.gov (United States)

    Abdollah-Nia, Farshad; Gelfand, Martin P; Van Orden, Alan

    2017-03-23

    Fluorescence correlation spectroscopy (FCS) is a powerful tool in the time-resolved analysis of nonreacting or reacting molecules in solution, based on fluorescence intensity fluctuations. However, conventional (second-order) FCS alone is insufficient to measure all parameters needed to describe a reaction or mixture, including concentrations, fluorescence brightnesses, and forward and reverse rate constants. For this purpose, correlations of higher powers of fluorescence intensity fluctuations can be calculated to yield additional information from the single-photon data stream collected in an FCS experiment. To describe systems of diffusing and reacting molecules, considering cumulants of fluorescence intensity results in simple expressions in which the reaction and diffusion parts factorize. The computation of higher-order correlations in experiments is hindered by shot-noise and common detector artifacts, the effects of which become worse with increasing order. In this article, we introduce a technique to calculate artifact-free higher-order correlation functions with improved time resolution, and without any need for modeling and calibration of detector artifacts. The technique is formulated for general multidetector experiments and verified in both two-detector and single-detector configurations. Good signal-to-noise ratio is achieved down to 1 μs in correlation curves up to order (2, 2). This capability makes possible a variety of new measurements including multicomponent analysis and fast reaction kinetics, as demonstrated in a companion article (10.1021/acs.jpcb.7b00408).

  19. Suitability of the first-order mass transfer concept for describing cyclic diffusive mass transfer in stagnant zones

    NARCIS (Netherlands)

    Griffioen, J.

    1998-01-01

    The concept of first-order mass transfer between mobile and immobile regions, which mathematically simplifies the concept of Fickian diffusion in stagnant areas, has often been used to describe physical nonequilibrium transport of solutes into natural porous media. This study compares the two

  20. Suitability of the first-order mass transfer concept for describing cyclic diffusive mass transfer in stagnant zones

    NARCIS (Netherlands)

    Griffioen, J.

    1998-01-01

    The concept of first-order mass transfer between mobile and immobile regions, which mathematically simplifies the concept of Fickian diffusion in stagnant areas, has often been used to describe physical nonequilibrium transport of solutes into natural porous media. This study compares the two concep

  1. A HIGH ORDER SOLUTION OF THREE DIMENSIONAL TIME DEPENDENT NONLINEAR CONVECTIVE-DIFFUSIVE PROBLEM USING MODIFIED VARIATIONAL ITERATION METHOD

    Directory of Open Access Journals (Sweden)

    Pratibha Joshi

    2014-12-01

    Full Text Available In this paper, we have achieved high order solution of a three dimensional nonlinear diffusive-convective problem using modified variational iteration method. The efficiency of this approach has been shown by solving two examples. All computational work has been performed in MATHEMATICA.

  2. Microstructural white matter changes in normal aging: a diffusion tensor imaging study with higher-order polynomial regression models.

    Science.gov (United States)

    Hsu, Jung-Lung; Van Hecke, Wim; Bai, Chyi-Huey; Lee, Cheng-Hui; Tsai, Yuh-Feng; Chiu, Hou-Chang; Jaw, Fu-Shan; Hsu, Chien-Yeh; Leu, Jyu-Gang; Chen, Wei-Hung; Leemans, Alexander

    2010-01-01

    Diffusion tensor imaging (DTI) has already proven to be a valuable tool when investigating both global and regional microstructural white matter (WM) brain changes in the human aging process. Although subject to many criticisms, voxel-based analysis is currently one of the most common and preferred approaches in such DTI aging studies. In this context, voxel-based DTI analyses have assumed a 'linear' correlation when finding the significant brain regions that relate age with a particular diffusion measure of interest. Recent literature, however, has clearly demonstrated 'non-linear' relationships between age and diffusion metrics by using region-of-interest and tractography-based approaches. In this work, we incorporated polynomial regression models in the voxel-based DTI analysis framework to assess age-related changes in WM diffusion properties (fractional anisotropy and axial, transverse, and mean diffusivity) in a large cohort of 346 subjects (25 to 81 years old). Our novel approach clearly demonstrates that voxel-based DTI analyses can greatly benefit from incorporating higher-order regression models when investigating potential relationships between aging and diffusion properties.

  3. Thermal Diffusivity of Ordered Double Perovskite A2FeMoO6 (A = Ca, Sr and Ba)

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-Jun; HUANG Qiao-Jian; NIU Dong-Lin; XU Sheng; ZHANG Shu-Yi

    2004-01-01

    @@ Thermal diffusivity has been investigated in ordered double perovskite Sr2FeMoO6 by means of transient surface grating technique in the temperature range of 300-450 K. The thermal diffusivity shows an appreciable decrease from 39mm2/s at 300 K to 37mm2/s at 360K in the ferromagnetic phase, and then steeply drops to 10mm2/s with further increasing temperature above the critical temperature Tc ~ 380 K. Such an abrupt decrease of the thermal diffusivity has been ascribed to the structural phase transition at Tc. We further investigate the lattice effect on the thermal diffusivity in A2FeMoO6 (A = Ca, Sr and Ba) by substitution of Ca2+ or Ba2+ ions for Sr2+ions at 300K. We find that the thermal diffusivity increases from 35mm2/s for A = Ca to 41 mm2/s for A = Ba.Considering the change of the Fe-O-Mo bond angle from 152.4° for A = Ca to 180° for A = Ba, the increased thermal diffusivity for Ba compound has been ascribed to the enhanced hybridization between transition-metal d and oxygen p states due to the larger Fe-O-Mo bond angle and hence the wider one-electron bandwidth W.

  4. Visibility spectroscopy with electron waves using a Wien filter: higher order corrections

    Science.gov (United States)

    Sonnentag; Kiesel; Hasselbach

    2000-08-01

    Fourier spectroscopy, one of the most precise spectrometry methods in light optics, has been realized in the past years with electron waves by including a crossed-field analyzer (Wien filter) as a wave packet shifting device into a biprism interferometer. To fully exploit the high precision of this method of determining the energy spectrum, higher order corrections stemming from the Wien filter's focusing action are necessary in the evaluation of the measurement. We show that these can be taken into account by using a transformation variable being proportional to the quotient of electric field strength of the Wien capacitor over fringe spacing. Finally, we make some remarks about the possibility of interference of inelastically scattered electrons.

  5. Fano resonance and the hidden order in URu2 Si 2 probed by quasiparticle scattering spectroscopy*

    Science.gov (United States)

    Park, W. K.; Greene, L. H.; Bauer, E. D.; Tobash, P. H.; Ronning, F.; Lu, X.; Sarrao, J. L.; Thompson, J. D.

    2011-03-01

    The nature of the hidden order transition occurring at 17.5 K in URu 2 Si 2 remains puzzling despite intensive investigations over the past two and half decades. Recent experimental and theoretical developments render it a timely subject to probe the hidden order state using quasiparticle tunneling and scattering techniques. We report on the Fano resonance in pure and Rh-doped URu 2 Si 2 single crystals using point-contact spectroscopy. The conductance spectra reproducibly reveal asymmetric double peak structures slightly off-centered around zero bias with the two peaks merging well above the hidden order transition temperature. An analysis using the Fano resonance model in a Kondo lattice [1] shows that the conductance peaks arise from the hybridization gap opening. Our estimated gap size agrees well with those reported from other measurements. We will present experimental results over a wide parameter space including temperature and doping dependences and discuss their underlying physics. M. Maltseva, M. Dzero, and P. Coleman, Phys. Rev. Lett. 103, 206402 (2009). * The work at UIUC is supported by the U.S. DOE under Award Nos. DE-FG02-07ER46453 and DE-AC02-98CH10886, and the work at LANL is carried out under the auspices of the U.S. DOE, Office of Science.

  6. Analysis of the human brain in primary progressive multiple sclerosis with mapping of the spatial distributions using 1H MR spectroscopy and diffusion tensor imaging.

    Science.gov (United States)

    Sijens, Paul E; Irwan, Roy; Potze, Jan Hendrik; Mostert, Jop P; De Keyser, Jacques; Oudkerk, Matthijs

    2005-08-01

    Primary progressive multiple sclerosis (ppMS; n=4) patients and controls (n=4) were examined by 1H magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in order to map choline (Cho), creatine and N-acetylaspartate (NAA), the fractional anisotropy (FA) and the apparent diffusion constant (ADC). After chemical shift imaging (point-resolved spectroscopy, repetition time/echo time 1,500 ms/135 ms) of a supraventricular volume of interest of 8x8x2 cm3 (64 voxels) MRS peak areas were matched to the results of DTI for the corresponding volume elements. Mean FA and NAA values were reduced in the ppMS patients (P<0.01, both) and the ADC increased (P<0.02). The spatial distribution of NAA showed strong correlation to ADC in both ppMS patients and controls (r =-0.74 and r= -0.70; P<0.00001, both), and weaker correlations to FA (r=0.49 and r=0.41; P<0.00001, all). FA and ADC also correlated significantly with Cho in patients and controls (P<0.00001, all). The relationship of Cho and NAA to the ADC and the FA and thus to the content of neuronal structures suggests that these metabolite signals essentially originate from axons (NAA) and the myelin sheath (Cho). This is of interest in view of previous reports in which Cho increases were associated with demyelination and the subsequent breakdown of neurons.

  7. Analysis of the human brain in primary progressive multiple sclerosis with mapping of the spatial distributions using {sup 1}H MR spectroscopy and diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sijens, Paul E.; Irwan, Roy; Potze, Jan Hendrik; Oudkerk, Matthijs [University Medical Center Groningen, Department of Radiology, Hanzeplein 1, Groningen (Netherlands); Mostert, Jop P.; Keyser, Jacques de [University Medical Center Groningen, Department of Neurology, Groningen (Netherlands)

    2005-08-01

    Primary progressive multiple sclerosis (ppMS; n=4) patients and controls (n=4) were examined by 1H magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in order to map choline (Cho), creatine and N-acetylaspartate (NAA), the fractional anisotropy (FA) and the apparent diffusion constant (ADC). After chemical shift imaging (point-resolved spectroscopy, repetition time/echo time 1,500 ms/135 ms) of a supraventricular volume of interest of 8 x 8 x 2 cm{sup 3} (64 voxels) MRS peak areas were matched to the results of DTI for the corresponding volume elements. Mean FA and NAA values were reduced in the ppMS patients (P<0.01, both) and the ADC increased (P<0.02). The spatial distribution of NAA showed strong correlation to ADC in both ppMS patients and controls (r =-0.74 and r= -0.70; P<0.00001, both), and weaker correlations to FA (r=0.49 and r=0.41; P<0.00001, all). FA and ADC also correlated significantly with Cho in patients and controls (P<0.00001, all). The relationship of Cho and NAA to the ADC and the FA and thus to the content of neuronal structures suggests that these metabolite signals essentially originate from axons (NAA) and the myelin sheath (Cho). This is of interest in view of previous reports in which Cho increases were associated with demyelination and the subsequent breakdown of neurons. (orig.)

  8. [Rapid identification of Dendrobium plants based on near infrared diffuse reflection spectroscopy].

    Science.gov (United States)

    Ding, Chang-Chun; Fang, Xiang-Jing; Zhao, Yan-Li; Li, Gui-Xiang; Li, Tao; Wang, Yuan-Zhong; Xia, Nian-He

    2014-01-01

    Near infrared diffuse reflection spectra of 15 species' 171 samples of Dendrobium combined with chemometrics statistical analysis were used to build prediction model, in order to discriminate different species of Dendrobium quickly and nondestructively. Hotelling T2 was applied to stability analysis of spectrum of 5 random drawing samples, and the results showed that the samples spectrum possessed good stability. Orthogonal test L24 (2 x 4 x 3 x 8) was designed to optimize optical path type, spectral band, derivative and smooth. The result of orthogonal test was analyzed by principal component analysis, which revealed that when 6500-4000 cm(-1) spectral band was applied, and with multiplicative scatter correction, second derivative, Norris smooth, and the number of principal components 7, the spectrum distinguishing accuracy was 100%. With the optimized condition of orthogonal test as the input value of partial least squares discriminant analysis and random drawing 123 samples as calibration set to establish the prediction model, and the rest 48 samples as prediction set were use to assess the property of the prediction model, the results indicated that the accumulating contribution rate of the first 3 principal components of the model was 99.36%, the identification of the standard deviation was +/- 0.1, and the correct recognition rate of the model was 97.92%. The results were satisfied. The method provided a new way for the rapid identification of different species of Dendrobium, and also supplied a reference for the authentication of medicinal plants.

  9. Exploiting Optical Contrasts for Cervical Precancer Diagnosis via Diffuse Reflectance Spectroscopy

    Science.gov (United States)

    Chang, Vivide Tuan-Chyan

    collagen without altering the amount of collagen present. Further work would be required to elucidate the exact sources of scattering contrast observed. Common confounding variables that limit the accuracy and clinical acceptability of optical spectroscopic systems are calibration requirements and variable probe-tissue contact pressures. Our results suggest that using a real-time self-calibration channel, as opposed to conventional post-experiment diffuse reflectance standard calibration measurements, significantly improved data integrity for the extraction of scattering contrast. Extracted [total Hb] and scattering were also significantly associated with applied contact probe pressure in colposcopically normal sites. Hence, future contact probe spectroscopy or imaging systems should incorporate a self-calibration channel and ensure spectral acquisition at a consistent contact pressure to collect reliable data with enhanced absorption and scattering contrasts. Another method to enhance optical contrast is to selectively interrogate different depths in the dysplastic cervix. For instance, scattering has been shown to increase in the epithelium (increase in nuclear-to-cytoplasmic ratio) while decrease in the stroma (re-organization of the extra-cellular matrix and changes in of collagen fiber cross-links). A fiber-optic probe with 45° illumination and collection fibers with a separation distance of 330 μm was designed and constructed to selectively interrogate the cervical epithelium. Mean extraction errors from liquid phantoms with optical properties mimicking the cervical epithelium for μa and μs' were 11.3 % and 12.7 %, respectively. Diffuse reflectance spectra from 9 sites in four loop electrosurgical excision procedure (LEEP) patients were analyzed. Preliminary data demonstrate the utility of the oblique fiber geometry in extracting scattering contrast in the cervical epithelium. Further work is needed to study the systematic error in optical property extraction and

  10. Assessing spatial variability of soil petroleum contamination using visible near-infrared diffuse reflectance spectroscopy.

    Science.gov (United States)

    Chakraborty, Somsubhra; Weindorf, David C; Zhu, Yuanda; Li, Bin; Morgan, Cristine L S; Ge, Yufeng; Galbraith, John

    2012-11-01

    Visible near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) is a rapid, non-destructive method for sensing the presence and amount of total petroleum hydrocarbon (TPH) contamination in soil. This study demonstrates the feasibility of VisNIR DRS to be used in the field to proximally sense and then map the areal extent of TPH contamination in soil. More specifically, we evaluated whether a combination of two methods, penalized spline regression and geostatistics could provide an efficient approach to assess spatial variability of soil TPH using VisNIR DRS data from soils collected from an 80 ha crude oil spill in central Louisiana, USA. Initially, a penalized spline model was calibrated to predict TPH contamination in soil by combining lab TPH values of 46 contaminated and uncontaminated soil samples and the first-derivative of VisNIR reflectance spectra of these samples. The r(2), RMSE, and bias of the calibrated penalized spline model were 0.81, 0.289 log(10) mg kg(-1), and 0.010 log(10) mg kg(-1), respectively. Subsequently, the penalized spline model was used to predict soil TPH content for 128 soil samples collected over the 80 ha study site. When assessed with a randomly chosen validation subset (n = 10) from the 128 samples, the penalized spline model performed satisfactorily (r(2) = 0.70; residual prediction deviation = 2.0). The same validation subset was used to assess point kriging interpolation after the remaining 118 predictions were used to produce an experimental semivariogram and map. The experimental semivariogram was fitted with an exponential model which revealed strong spatial dependence among soil TPH [r(2) = 0.76, nugget = 0.001 (log(10) mg kg(-1))(2), and sill 1.044 (log(10) mg kg(-1))(2)]. Kriging interpolation adequately interpolated TPH with r(2) and RMSE values of 0.88 and 0.312 log(10) mg kg(-1), respectively. Furthermore, in the kriged map, TPH distribution matched with the expected TPH variability of the study site. Since the

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

    Science.gov (United States)

    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 20-44 years were diagnosed as healthy and probed with a portable DRS system. Diffuse reflectance spectra were recorded in vivo in the range (450-650 nm). 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 620 nm). 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 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.

  12. Fiber-bundle microendoscopy with sub-diffuse reflectance spectroscopy and intensity mapping for multimodal optical biopsy of stratified epithelium.

    Science.gov (United States)

    Greening, Gage J; James, Haley M; Powless, Amy J; Hutcheson, Joshua A; Dierks, Mary K; Rajaram, Narasimhan; Muldoon, Timothy J

    2015-12-01

    Early detection of structural or functional changes in dysplastic epithelia may be crucial for improving long-term patient care. Recent work has explored myriad non-invasive or minimally invasive "optical biopsy" techniques for diagnosing early dysplasia, such as high-resolution microendoscopy, a method to resolve sub-cellular features of apical epithelia, as well as broadband sub-diffuse reflectance spectroscopy, a method that evaluates bulk health of a small volume of tissue. We present a multimodal fiber-based microendoscopy technique that combines high-resolution microendoscopy, broadband (450-750 nm) sub-diffuse reflectance spectroscopy (sDRS) at two discrete source-detector separations (374 and 730 μm), and sub-diffuse reflectance intensity mapping (sDRIM) using a 635 nm laser. Spatial resolution, magnification, field-of-view, and sampling frequency were determined. Additionally, the ability of the sDRS modality to extract optical properties over a range of depths is reported. Following this, proof-of-concept experiments were performed on tissue-simulating phantoms made with poly(dimethysiloxane) as a substrate material with cultured MDA-MB-468 cells. Then, all modalities were demonstrated on a human melanocytic nevus from a healthy volunteer and on resected colonic tissue from a murine model. Qualitative in vivo image data is correlated with reduced scattering and absorption coefficients.

  13. Linear, third- and fifth-order nonlinear spectroscopy of a charge transfer system coupled to an underdamped vibration

    CERN Document Server

    Dijkstra, Arend G

    2015-01-01

    We study hole, electron and exciton transport in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole and exciton transfer can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states du...

  14. Medulloblastoma: correlation among findings of conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fonte, Mariana Vieira de Melo da; Otaduy, Maria Concepcion Garcia; Lucato, Leandro Tavares; Reed, Umbertina Conti; Leite, Claudia da Costa [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Hospital das Clinicas. Inst. de Radiologia]. E-mail: mvmfonte@uol.com.br; Costa, Maria Olivia Rodrigues; Amaral, Raquel Portugal Guimaraes [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Dept. de Radiologia; Reed, Umbertina Conti [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Dept. de Neurologia; Rosemberg, Sergio [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Hospital das Clinicas. Dept. de Patologia

    2008-11-15

    To correlate imaging findings of medulloblastomas at conventional magnetic resonance imaging, diffusion-weighted imaging and proton magnetic resonance spectroscopy, comparing them with data in the literature. Preoperative magnetic resonance imaging studies of nine pediatric patients with histologically confirmed medulloblastomas (eight desmoplastic medulloblastoma, and one giant cell medulloblastoma) were retrospectively reviewed, considering demographics as well as tumors characteristics such as localization, morphology, signal intensity, contrast-enhancement, dissemination, and diffusion-weighted imaging and spectroscopy findings. In most of cases the tumors were centered in the cerebellar vermis (77.8%), predominantly solid (88.9%), hypointense on T 1-weighted images and intermediate/hyperintense on T 2-FLAIR-weighted images, with heterogeneous enhancement (100%), tumor dissemination/extension (77.8%) and limited water molecule mobility (100%). Proton spectroscopy acquired with STEAM technique (n = 6) demonstrated decreased Na a / Cr ratio (83.3%) and increased Co/Cr (100%) and ml/Cr (66.7%) ratios; and with PRESS technique (n = 7) demonstrated lactate peak (57.1%). Macroscopic magnetic resonance imaging findings in association with biochemical features of medulloblastomas have been useful in the differentiation among the most frequent posterior fossa tumors. (author)

  15. Crystal structure refinement and Mössbauer spectroscopy of an ordered, triclinic clinochlore

    Science.gov (United States)

    Smyth, Joseph R.; Dyar, M. Darby; May, Howard M.; Bricker, Owen P.; Acker, James G.

    1997-01-01

    The crystal structure of a natural, ordered IIb-4 triclinic clinochlore has been refined in space group C1¯ from 4282 unique X-ray intensity measurements of which 3833 are greater than 3 times the statistical counting error (3σ). Unit cell parameters are a = 5.3262(6) Å; b = 9.226(1) Å; c = 14.334(3) Å; α = 90.56(2)°; β = 97.47(2)°; and γ = 89.979(9)°, which represents the greatest deviation from monoclinic symmetry yet recorded for a triclinic chlorite. The final weighted R is 0.059 for reflections with I > 3σ and 0.064 for all reflections. The chemical formula is (Mg0.966Fe0.034)M1(Mg0.962Fe0.038)M22(Si2.96Al1.04)O10 (OH)2(Mg0.996Fe0.004)M32(Al0.841FeIII0.102Cr0.004Ti0.004)M4(OH)6, which is consistent with electron microprobe (EMP), wet chemical analyses, Mössbauer spectroscopy and X-ray structure refinement. The high degree of ordering of the divalent versus trivalent octahedral cations in the interlayer is noteworthy, with FeIII and Al in M4 and virtually no Fe in M3. In the 2:1 layer, M1 and M2 each contain similar amounts of Fe. The 2 tetrahedral sites have nearly identical mean oxygen distances and volumes, and thus show no evidence of long-range cation ordering.

  16. Theoretical analysis of the velocity field, stress field and vortex sheet of generalized second order fluid withfractional anomalous diffusion

    Institute of Scientific and Technical Information of China (English)

    徐明瑜; 谭文长

    2001-01-01

    The velocity field of generalized second order fluid with fractional anomalous diffusion caused by a plate moving impulsively in its own plane is investigated and the anomalous diffusion problems of the stress field and vortex sheet caused by this process are studied. Many previous and classical results can be considered as particular cases of this paper, such as the solutions of the fractional diffusion equations obtained by Wyss; the classical Rayleigh' s time-space similarity solution; the relationship between stress field and velocity field obtained by Bagley and co-worker and Podlubny' s results on the fractional motion equation of a plate. In addition, a lot of significant results also are obtained. For example, the necessary condition for causing the vortex sheet is that the time fractional diffusion index β must be greater than that of generalized second order fluid α; the establishment of the vorticity distribution function depends on the time history of the velocity profile at a given point, and the time history can be described by the fractional calculus.

  17. Resin characterization in cured graphite fiber reinforced composites using diffuse reflectance-FTIR. [Fourier transform infrared spectroscopy

    Science.gov (United States)

    Young, P. R.; Stein, B. A.; Chang, A. C.

    1983-01-01

    The feasibility of using diffuse reflectance in combination with Fourier transform infrared spectroscopy to obtain information on cured graphite fiber reinforced polymeric matrix resin composites was investigated. Several graphite/epoxy, polysulfone, and polyimide composites exposed to thermal or radiation environments were examined. An experimental polyimide-sulfone adhesive tape was also studied during processing. In each case, significant changes in resin molecular structure was observed due to environmental exposure. These changes in molecular structure were correlated with previously observed changes in material properties providing new insights into material behavior.

  18. In vivo preclinical verification of a multimodal diffuse reflectance and correlation spectroscopy system for sensing tissue perfusion

    Science.gov (United States)

    Pakela, Julia M.; Lee, Seung Yup; Hedrick, Taylor L.; Vishwanath, Karthik; Helton, Michael C.; Chung, Yooree G.; Kolodziejski, Noah J.; Staples, Christopher J.; McAdams, Daniel R.; Fernandez, Daniel E.; Christian, James F.; O'Reilly, Jameson; Farkas, Dana; Ward, Brent B.; Feinberg, Stephen E.; Mycek, Mary-Ann

    2017-02-01

    In reconstructive surgery, impeded blood flow in microvascular free flaps due to a compromise in arterial or venous patency secondary to blood clots or vessel spasms can rapidly result in flap failures. Thus, the ability to detect changes in microvascular free flaps is critical. In this paper, we report progress on in vivo pre-clinical testing of a compact, multimodal, fiber-based diffuse correlation and reflectance spectroscopy system designed to quantitatively monitor tissue perfusion in a porcine model's surgically-grafted free flap. We also describe the device's sensitivity to incremental blood flow changes and discuss the prospects for continuous perfusion monitoring in future clinical translational studies.

  19. Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

    Science.gov (United States)

    Svensson, Tomas; Lewander, Märta; Svanberg, Sune

    2010-08-02

    We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

  20. Critical comparison of diffuse reflectance spectroscopy and colorimetry as dermatological diagnostic tools for acanthosis nigricans: a chemometric approach.

    Science.gov (United States)

    Devpura, Suneetha; Pattamadilok, Bensachee; Syed, Zain U; Vemulapalli, Pranita; Henderson, Marsha; Rehse, Steven J; Hamzavi, Iltefat; Lim, Henry W; Naik, Ratna

    2011-06-01

    Quantification of skin changes due to acanthosis nigricans (AN), a disorder common among insulin-resistant diabetic and obese individuals, was investigated using two optical techniques: diffuse reflectance spectroscopy (DRS) and colorimetry. Measurements were obtained from AN lesions on the neck and two control sites of eight AN patients. A principal component/discriminant function analysis successfully differentiated between AN lesion and normal skin with 87.7% sensitivity and 94.8% specificity in DRS measurements and 97.2% sensitivity and 96.4% specificity in colorimetry measurements.

  1. Ballistic and diffusive current spin polarization in L1{sub o}-ordered FePt and FePd

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, Klaus M.; Baltz, Vincent; Hickey, Mark C.; Marrows, Christopher H.; Hickey, Bryan J. [E.C. Stoner Laboratory, School of Physics and Astronomy, University of Leeds, Leeds (United Kingdom); MacKenzie, Maureen; Chapman, John N. [Department of Physics and Astronomy, University of Glasgow, Glasgow (United Kingdom); Miguel, Jorge; Kuch, Wolfgang [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Berlin (Germany); Kronast, Florian [BESSY, Albert-Einstein-Strasse 15, Berlin (Germany)

    2008-07-01

    We report on the discrepancy of the current spin polarization in the ballistic and diffusive electron transport regime in L1{sub o}-ordered epitaxial FePt and FePd layers. The films studied displayed a chemical long range order parameter of 0.4diffusive spin current polarization to be 80-90. On the other hand, to study the ballistic transport regime we have performed point-contact Andreev-reflection measurements at 4.2 K. We obtained a value for the ballistic current spin polarization of 50%.

  2. Nonexponential decay of velocity correlations in surface diffusion: The role of interactions and ordering

    DEFF Research Database (Denmark)

    Vattulainen, Ilpo Tapio; Hjelt, T.; Ala-Nissila, T.

    2000-01-01

    We study the diffusive dynamics of adparticles in two model systems with strong interactions by considering the decay of the single-particle velocity correlation function phi (t). In accordance with previous studies, we find phi (t) to decay nonexponentially and follow a power-law phi (t)similar ......We study the diffusive dynamics of adparticles in two model systems with strong interactions by considering the decay of the single-particle velocity correlation function phi (t). In accordance with previous studies, we find phi (t) to decay nonexponentially and follow a power-law phi (t...... be rationalized in terms of interaction effects. Namely, x is typically larger than two in cases where repulsive adparticle-adparticle interactions dominate, while attractive interactions lead to x...

  3. The use of fluorescence correlation spectroscopy to probe mitochondrial mobility and intramatrix protein diffusion

    NARCIS (Netherlands)

    P.H.G.M. Willems; H.G. Swarts; M.A. Hink; W.J.H. Koopman

    2009-01-01

    Within cells, functional changes in mitochondrial metabolic state are associated with alterations in organelle mobility, shape, and configuration of the mitochondrial matrix. Fluorescence correlation spectroscopy (FCS) is a technique that measures intensity fluctuations caused by single fluorescent

  4. Mapping breast cancer blood flow index, composition, and metabolism in a human subject using combined diffuse optical spectroscopic imaging and diffuse correlation spectroscopy

    Science.gov (United States)

    Yazdi, Hossein S.; O'Sullivan, Thomas D.; Leproux, Anais; Hill, Brian; Durkin, Amanda; Telep, Seraphim; Lam, Jesse; Yazdi, Siavash S.; Police, Alice M.; Carroll, Robert M.; Combs, Freddie J.; Strömberg, Tomas; Yodh, Arjun G.; Tromberg, Bruce J.

    2017-04-01

    Diffuse optical spectroscopic imaging (DOSI) and diffuse correlation spectroscopy (DCS) are model-based near-infrared (NIR) methods that measure tissue optical properties (broadband absorption, μa, and reduced scattering, μs‧) and blood flow (blood flow index, BFI), respectively. DOSI-derived μa values are used to determine composition by calculating the tissue concentration of oxy- and deoxyhemoglobin (HbO2, HbR), water, and lipid. We developed and evaluated a combined, coregistered DOSI/DCS handheld probe for mapping and imaging these parameters. We show that uncertainties of 0.3 mm-1 (37%) in μs‧ and 0.003 mm-1 (33%) in μa lead to ˜53% and 9% errors in BFI, respectively. DOSI/DCS imaging of a solid tissue-simulating flow phantom and a breast cancer patient reveals well-defined spatial distributions of BFI and composition that clearly delineates both the flow channel and the tumor. BFI reconstructed with DOSI-corrected μa and μs‧ values had a tumor/normal contrast of 2.7, 50% higher than the contrast using commonly assumed fixed optical properties. In conclusion, spatially coregistered imaging of DOSI and DCS enhances intrinsic tumor contrast and information content. This is particularly important for imaging diseased tissues where there are significant spatial variations in μa and μs‧ as well as potential uncoupling between flow and metabolism.

  5. Noninvasive observation of skeletal muscle contraction using near-infrared time-resolved reflectance and diffusing-wave spectroscopy

    Science.gov (United States)

    Belau, Markus; Ninck, Markus; Hering, Gernot; Spinelli, Lorenzo; Contini, Davide; Torricelli, Alessandro; Gisler, Thomas

    2010-09-01

    We introduce a method for noninvasively measuring muscle contraction in vivo, based on near-infrared diffusing-wave spectroscopy (DWS). The method exploits the information about time-dependent shear motions within the contracting muscle that are contained in the temporal autocorrelation function g(1)(τ,t) of the multiply scattered light field measured as a function of lag time, τ, and time after stimulus, t. The analysis of g(1)(τ,t) measured on the human M. biceps brachii during repetitive electrical stimulation, using optical properties measured with time-resolved reflectance spectroscopy, shows that the tissue dynamics giving rise to the speckle fluctuations can be described by a combination of diffusion and shearing. The evolution of the tissue Cauchy strain e(t) shows a strong correlation with the force, indicating that a significant part of the shear observed with DWS is due to muscle contraction. The evolution of the DWS decay time shows quantitative differences between the M. biceps brachii and the M. gastrocnemius, suggesting that DWS allows to discriminate contraction of fast- and slow-twitch muscle fibers.

  6. Preliminary evaluation of optical glucose sensing in red cell concentrations using near-infrared diffuse-reflectance spectroscopy

    Science.gov (United States)

    Suzuki, Yusuke; Maruo, Katsuhiko; Zhang, Alice W.; Shimogaki, Kazushige; Ogawa, Hideto; Hirayama, Fumiya

    2012-01-01

    Bacterial contamination of blood products is one of the most frequent infectious complications of transfusion. Since glucose levels in blood supplies decrease as bacteria proliferate, it should be possible to detect the presence of bacterial contamination by measuring the glucose concentrations in the blood components. Hence this study is aimed to serve as a preliminary study for the nondestructive measurement of glucose level in transfusion blood. The glucose concentrations in red blood cell (RBC) samples were predicted using near-infrared diffuse-reflectance spectroscopy in the 1350 to 1850 nm wavelength region. Furthermore, the effects of donor, hematocrit level, and temperature variations among the RBC samples were observed. Results showed that the prediction performance of a dataset which contained samples that differed in all three parameters had a standard error of 29.3 mg/dL. Multiplicative scatter correction (MSC) preprocessing method was also found to be effective in minimizing the variations in scattering patterns created by various sample properties. The results suggest that the diffuse-reflectance spectroscopy may provide another avenue for the detection of bacterial contamination in red cell concentrations (RCC) products.

  7. Ultrafast charge separation dynamics in opaque, operational dye-sensitized solar cells revealed by femtosecond diffuse reflectance spectroscopy

    Science.gov (United States)

    Ghadiri, Elham; Zakeeruddin, Shaik M.; Hagfeldt, Anders; Grätzel, Michael; Moser, Jacques-E.

    2016-04-01

    Efficient dye-sensitized solar cells are based on highly diffusive mesoscopic layers that render these devices opaque and unsuitable for ultrafast transient absorption spectroscopy measurements in transmission mode. We developed a novel sub-200 femtosecond time-resolved diffuse reflectance spectroscopy scheme combined with potentiostatic control to study various solar cells in fully operational condition. We studied performance optimized devices based on liquid redox electrolytes and opaque TiO2 films, as well as other morphologies, such as TiO2 fibers and nanotubes. Charge injection from the Z907 dye in all TiO2 morphologies was observed to take place in the sub-200 fs time scale. The kinetics of electron-hole back recombination has features in the picosecond to nanosecond time scale. This observation is significantly different from what was reported in the literature where the electron-hole back recombination for transparent films of small particles is generally accepted to occur on a longer time scale of microseconds. The kinetics of the ultrafast electron injection remained unchanged for voltages between +500 mV and -690 mV, where the injection yield eventually drops steeply. The primary charge separation in Y123 organic dye based devices was clearly slower occurring in two picoseconds and no kinetic component on the shorter femtosecond time scale was recorded.

  8. Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1968-01-01

    This booklet discusses spectroscopy, the study of absorption of radiation by matter, including X-ray, gamma-ray, microwave, mass spectroscopy, as well as others. Spectroscopy has produced more fundamental information to the study of the detailed structure of matter than any other tools.

  9. Time-Resolved Diffuse Optical Spectroscopy and Imaging Using Solid-State Detectors: Characteristics, Present Status, and Research Challenges.

    Science.gov (United States)

    Alayed, Mrwan; Deen, M Jamal

    2017-09-14

    Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are emerging non-invasive imaging modalities that have wide spread potential applications in many fields, particularly for structural and functional imaging in medicine. In this article, we review time-resolved diffuse optical imaging (TR-DOI) systems using solid-state detectors with a special focus on Single-Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). These TR-DOI systems can be categorized into two types based on the operation mode of the detector (free-running or time-gated). For the TR-DOI prototypes, the physical concepts, main components, figures-of-merit of detectors, and evaluation parameters are described. The performance of TR-DOI prototypes is evaluated according to the parameters used in common protocols to test DOI systems particularly basic instrumental performance (BIP). In addition, the potential features of SPADs and SiPMs to improve TR-DOI systems and expand their applications in the foreseeable future are discussed. Lastly, research challenges and future developments for TR-DOI are discussed for each component in the prototype separately and also for the entire system.

  10. Spectroscopy

    CERN Document Server

    Walker, S

    1976-01-01

    The three volumes of Spectroscopy constitute the one comprehensive text available on the principles, practice and applications of spectroscopy. By giving full accounts of those spectroscopic techniques only recently introduced into student courses - such as Mössbauer spectroscopy and photoelectron spectroscopy - in addition to those techniques long recognised as being essential in chemistry teaching - sucha as e.s.r. and infrared spectroscopy - the book caters for the complete requirements of undergraduate students and at the same time provides a sound introduction to special topics for graduate students.

  11. Heterogeneous nanoparticles at water-oil interfaces: Structure, Order, Diffusion, and Implications for the stability of Pickering emulsions

    Science.gov (United States)

    Striolo, Alberto; Luu, Xuan-Cuong; Molecular Science and Engineering Team

    2013-03-01

    Pickering emulsions find applications, e.g., in food processing, personal care products, and drug delivery. The emulsions stability is naturally related to the structural and dynamical properties of the nanoparticles adsorbed at oil-water interfaces. Such properties are investigated here by means of dissipative particle dynamics simulations, informed by atomistic molecular dynamics simulations results (Langmuir2011, 27, (9), 5264-5274). Several nanoparticles are considered, including Janus and homogeneous, and of several different shapes (spherical, elliptical, discoid, etc.) Structural and transport properties are quantified as a function of surface density and system composition. Results for radial distribution functions, hexagonal order parameters, and self-diffusion coefficients are reported. We sometimes find unexpected behavior. For example, self-diffusion coefficient maxima are observed in mixed systems. Implications of such observations on macroscopic observables (i.e., the stability of Pickering emulsions) are discussed. Acknowledgments: NSF

  12. Fast spatiotemporal correlation spectroscopy to determine protein lateral diffusion laws in live cell membranes.

    Science.gov (United States)

    Di Rienzo, Carmine; Gratton, Enrico; Beltram, Fabio; Cardarelli, Francesco

    2013-07-23

    Spatial distribution and dynamics of plasma-membrane proteins are thought to be modulated by lipid composition and by the underlying cytoskeleton, which forms transient barriers to diffusion. So far this idea was probed by single-particle tracking of membrane components in which gold particles or antibodies were used to individually monitor the molecules of interest. Unfortunately, the relatively large particles needed for single-particle tracking can in principle alter the very dynamics under study. Here, we use a method that makes it possible to investigate plasma-membrane proteins by means of small molecular labels, specifically single GFP constructs. First, fast imaging of the region of interest on the membrane is performed. For each time delay in the resulting stack of images the average spatial correlation function is calculated. We show that by fitting the series of correlation functions, the actual protein "diffusion law" can be obtained directly from imaging, in the form of a mean-square displacement vs. time-delay plot, with no need for interpretative models. This approach is tested with several simulated 2D diffusion conditions and in live Chinese hamster ovary cells with a GFP-tagged transmembrane transferrin receptor, a well-known benchmark of membrane-skeleton-dependent transiently confined diffusion. This approach does not require extraction of the individual trajectories and can be used also with dim and dense molecules. We argue that it represents a powerful tool for the determination of kinetic and thermodynamic parameters over very wide spatial and temporal scales.

  13. In vivo characterization of colorectal metastases in human liver using diffuse reflectance spectroscopy: toward guidance in oncological procedures

    Science.gov (United States)

    Spliethoff, Jarich W.; de Boer, Lisanne L.; Meier, Mark A. J.; Prevoo, Warner; de Jong, Jeroen; Kuhlmann, Koert; Bydlon, Torre M.; Sterenborg, Henricus J. C. M.; Hendriks, Benno H. W.; Ruers, Theo J. M.

    2016-09-01

    There is a strong need to develop clinical instruments that can perform rapid tissue assessment at the tip of smart clinical instruments for a variety of oncological applications. This study presents the first in vivo real-time tissue characterization during 24 liver biopsy procedures using diffuse reflectance (DR) spectroscopy at the tip of a core biopsy needle with integrated optical fibers. DR measurements were performed along each needle path, followed by biopsy of the target lesion using the same needle. Interventional imaging was coregistered with the DR spectra. Pathology results were compared with the DR spectroscopy data at the final measurement position. Bile was the primary discriminator between normal liver tissue and tumor tissue. Relative differences in bile content matched with the tissue diagnosis based on histopathological analysis in all 24 clinical cases. Continuous DR measurements during needle insertion in three patients showed that the method can also be applied for biopsy guidance or tumor recognition during surgery. This study provides an important validation step for DR spectroscopy-based tissue characterization in the liver. Given the feasibility of the outlined approach, it is also conceivable to make integrated fiber-optic tools for other clinical procedures that rely on accurate instrument positioning.

  14. Optimal control problem for a sixth-order Cahn-Hilliard equation with nonlinear diffusion

    Directory of Open Access Journals (Sweden)

    Changchun Liu

    2012-08-01

    Full Text Available In this article, we study the initial-boundary-value problem for a sixth-order Cahn-Hilliard type equation $$displaylines{ u_t=D^2mu, cr mu=gamma D^4u-a(uD^2u-frac{a'(u}2|D u|^2+f(u+ku_t, }$$ which describes the separation properties of oil-water mixtures, when a substance enforcing the mixing of the phases is added. The optimal control of the sixth order Cahn-Hilliard type equation under boundary condition is given and the existence of optimal solution to the sixth order Cahn-Hilliard type equation is proved.

  15. Numerical solution of fractional sub-diffusion and time-fractional diffusion-wave equations via fractional-order Legendre functions

    Science.gov (United States)

    Hooshmandasl, M. R.; Heydari, M. H.; Cattani, C.

    2016-08-01

    Fractional calculus has been used to model physical and engineering processes that are best described by fractional differential equations. Therefore designing efficient and reliable techniques for the solution of such equations is an important task. In this paper, we propose an efficient and accurate Galerkin method based on the fractional-order Legendre functions (FLFs) for solving the fractional sub-diffusion equation (FSDE) and the time-fractional diffusion-wave equation (FDWE). The time-fractional derivatives for FSDE are described in the Riemann-Liouville sense, while for FDWE are described in the Caputo sense. To this end, we first derive a new operational matrix of fractional integration (OMFI) in the Riemann-Liouville sense for FLFs. Next, we transform the original FSDE into an equivalent problem with fractional derivatives in the Caputo sense. Then the FLFs and their OMFI together with the Galerkin method are used to transform the problems under consideration into the corresponding linear systems of algebraic equations, which can be simply solved to achieve the numerical solutions of the problems. The proposed method is very convenient for solving such kind of problems, since the initial and boundary conditions are taken into account automatically. Furthermore, the efficiency of the proposed method is shown for some concrete examples. The results reveal that the proposed method is very accurate and efficient.

  16. Crystal polymorphism: dependence of oxygen diffusion through 2D ordered Co nanocrystals.

    Science.gov (United States)

    Yang, Zhijie; Yang, Jianhui; Bergström, Johanna; Khazen, Khashayar; Pileni, Marie-Paule

    2014-06-07

    8 nm Co nanoparticles with various crystalline structures called polymorphs were produced using different synthetic procedures, such as using reverse micelles, the thermal decomposition of organometallics approach or the hot injection process. These 8 nm Co nanoparticles differing by their crystalline structures are exposed to oxygen at elevated temperature. The fcc Co polycrystalline nanoparticles produce either Co-CoO yolk-shell or CoO hollow structures whereas amorphous Co nanoparticles produce Co-CoO core-shell nanoparticles. Furthermore, single domains with either hcp or ε crystalline structure behave differently upon oxygen diffusion. Co-CoO nanoparticles were produced from the hcp phase while CoO hollow nanoparticles were the product for ε-phase Co nanocrystals.

  17. ON SOME MODEL DIFFUSION PROBLEMS WITH A NONLOCAL LOWER ORDER TERM

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The authors consider a class of nonlinear parabolic problems where the lower order term isdepending on a weighted integral of the solution, and address the issues of existence, uniqueness,stationary solutions and in some cases asymptotic behaviour.

  18. Improved identification of peripheral lung tumors by using diffuse reflectance and fluorescence spectroscopy

    NARCIS (Netherlands)

    Spliethoff, J.W.; Spliethoff, Jarich; Evers, Daniel; Evers, D.J.; Klomp, H.M.; van Sandick, J.W.; Wouters, M.W.J.M.; Nachabe, R.; Lucassen, G.W.; Lucassen, Gerald; Hendriks, B.H.W.; Wesseling, J.; Ruers, Theo J.M.

    2013-01-01

    Introduction: A significant number of transthoracic diagnostic biopsy procedures for lung lesions show indeterminate results. Such failures are potentially due to inadequate recognition of vital tumor tissue. The objective of this study was to evaluate whether optical spectroscopy at the tip of a

  19. First-Order Hyperbolic System Method for Time-Dependent Advection-Diffusion Problems

    Science.gov (United States)

    2014-03-01

    fully-implicit steady solver with exact linearization , i.e., Newton’s method, for a second-order upwind scheme. The strategy taken here may be thought...second-order accuracy is achieved within a compact stencil, thus allowing the exact linearization with a sparse Jacobian matrix. The same is true for...a much larger num- ber of outer iterations as well if the exact linearization is not possible and Newton’s method cannot be constructed. Hence, the

  20. A new family of implicit fourth order compact schemes for unsteady convection-diffusion equation with variable convection coefficient

    CERN Document Server

    Sen, Shuvam

    2012-01-01

    In this paper, a new family of implicit compact finite difference schemes for computation of unsteady convection-diffusion equation with variable convection coefficient is proposed. The schemes are fourth order accurate in space and second or lower order accurate in time depending on the choice of weighted time average parameter. The proposed schemes, where transport variable and its first derivatives are carried as the unknowns, combine virtues of compact discretization and Pad\\'{e} scheme for spatial derivative. These schemes which are based on five point stencil with constant coefficients, named as \\emph{(5,5) Constant Coefficient 4th Order Compact} [(5,5)CC-4OC], give rise to a diagonally dominant system of equations and shows higher accuracy and better phase and amplitude error characteristics than some of the standard methods. These schemes are capable of using a grid aspect ratio other than unity and are unconditionally stable. They efficiently capture both transient and steady solutions of linear and ...

  1. Determination of diffusion coefficients of hydrogen in fused silica between 296 and 523 K by Raman spectroscopy and application of fused silica capillaries in studying redox reactions

    Science.gov (United States)

    Shang, L.; Chou, I.-Ming; Lu, W.; Burruss, R.C.; Zhang, Y.

    2009-01-01

    Diffusion coefficients (D) of hydrogen in fused silica capillaries (FSC) were determined between 296 and 523 K by Raman spectroscopy using CO2 as an internal standard. FSC capsules (3.25 ?? 10-4 m OD, 9.9 ?? 10-5 m ID, and ???0.01 m long) containing CO2 and H2 were prepared and the initial relative concentrations of hydrogen in these capsules were derived from the Raman peak-height ratios between H2 (near 587 cm-1) and CO2 (near 1387 cm-1). The sample capsules were then heated at a fixed temperature (T) at one atmosphere to let H2 diffuse out of the capsule, and the changes of hydrogen concentration were monitored by Raman spectroscopy after quench. This process was repeated using different heating durations at 296 (room T), 323, 375, 430, 473, and 523 K; the same sample capsule was used repeatedly at each temperature. The values of D (in m2 s-1) in FSC were obtained by fitting the observed changes of hydrogen concentration in the FSC capsule to an equation based on Fick's law. Our D values are in good agreement with the more recent of the two previously reported experimental data sets, and both can be represented by: ln D = - (16.471 ?? 0.035) - frac(44589 ?? 139, RT) (R2 = 0.99991) where R is the gas constant (8.3145 J/mol K), T in Kelvin, and errors at 1?? level. The slope corresponds to an activation energy of 44.59 ?? 0.14 kJ/mol. The D in FSC determined at 296 K is about an order of magnitude higher than that in platinum at 723 K, indicating that FSC is a suitable membrane for hydrogen at temperature between 673 K and room temperature, and has a great potential for studying redox reactions at these temperatures, especially for systems containing organic material and/or sulphur. ?? 2009 Elsevier Ltd.

  2. Optical spectroscopy of spontaneously-ordered GaInP2 with sub-micron spatial resolution

    Science.gov (United States)

    Smith, S.; Geisz, J. F.; Olson, J. M.; Kazmerski, L. L.; Mascarenhas, A.

    2000-03-01

    The low-temperature (5K) photoluminescence of partially-ordered GaInP2 is spatially resolved (spatial resolution ~ 0.7-0.2μm) using scanning far-field and near-field microscopy combined with photoluminescence spectroscopy (energy resolution ~ 40μeV). In a series of samples where the order parameter η varies from ~ 0 to 0.45, we observe a systematic reduction in the excitonic linewidth with order parameter, which can be explained in terms of the decrease in alloy scattering as a consequence of spontaneous ordering. We also observe the competing linewidth-broadening associated with exciton localization, which begins to overcome the ordering-induced linewidth reduction for highly ordered alloys. Using the near-field technique, we spatially localize several of the 'quantum-dot-like' transitions, which appear in the vicinity of the below-gap emission, with respect to the underlying ordered-domain structure.

  3. Brain changes in long-term zen meditators using proton magnetic resonance spectroscopy and diffusion tensor imaging: a controlled study.

    Directory of Open Access Journals (Sweden)

    Nicolás Fayed

    Full Text Available INTRODUCTION: This work aimed to determine whether (1H magnetic resonance imaging (MRI, magnetic resonance spectroscopy (MRS, diffusion-weighted imaging (DWI and diffusion tensor imaging (DTI are correlated with years of meditation and psychological variables in long-term Zen meditators compared to healthy non-meditator controls. MATERIALS AND METHODS: Design. Controlled, cross-sectional study. Sample. Meditators were recruited from a Zen Buddhist monastery. The control group was recruited from hospital staff. Meditators were administered questionnaires on anxiety, depression, cognitive impairment and mindfulness. (1H-MRS (1.5 T of the brain was carried out by exploring four areas: both thalami, both hippocampi, the posterior superior parietal lobule (PSPL and posterior cingulate gyrus. Predefined areas of the brain were measured for diffusivity (ADC and fractional anisotropy (FA by MR-DTI. RESULTS: Myo-inositol (mI was increased in the posterior cingulate gyrus and Glutamate (Glu, N-acetyl-aspartate (NAA and N-acetyl-aspartate/Creatine (NAA/Cr was reduced in the left thalamus in meditators. We found a significant positive correlation between mI in the posterior cingulate and years of meditation (r = 0.518; p = .019. We also found significant negative correlations between Glu (r = -0.452; p = .045, NAA (r = -0.617; p = .003 and NAA/Cr (r = -0.448; P = .047 in the left thalamus and years of meditation. Meditators showed a lower Apparent Diffusion Coefficient (ADC in the left posterior parietal white matter than did controls, and the ADC was negatively correlated with years of meditation (r = -0.4850, p = .0066. CONCLUSIONS: The results are consistent with the view that mI, Glu and NAA are the most important altered metabolites. This study provides evidence of subtle abnormalities in neuronal function in regions of the white matter in meditators.

  4. Measurement of Retinalamin diffusion coefficient in human sclera by optical spectroscopy

    Science.gov (United States)

    Genina, Elina A.; Bashkatov, Alexey N.; Zubkova, Elena A.; Kamenskikh, Tatiana G.; Tuchin, Valery V.

    2008-12-01

    The use of cytomedines (such as Retinalamin) in clinical practice has shown high effectiveness of the medicaments in ophthalmology. The study of diffusion of Retinalamin in scleral tissue is important for estimation of a drug dose delivered into inner tissue of eye, time of drug action, etc. In vitro measurements of spectral reflectance of sclera interacting with aqueous solution of Retinalamin have been carried out. Ten human sclera samples were included in the study. The results of the experiments have shown that penetration of Retinalamin into scleral tissue leads to the decrease of scleral reflectance due to optical immersion. Estimation of diffusion coefficient of studied solution has been made on the basis of analysis of optical reflectance dynamics of the sclera samples. The diffusion coefficient of Retinalamin in human scleral tissue was evaluated as (1.82±0.14)×10 -6 cm 2/s. The results are important for treatment of partial optic atrophy observed at primary open-angle glaucoma and others eye diseases.

  5. Diffusive behavior and the modeling of characteristic times in limit order executions

    CERN Document Server

    Eisler, Z; Lillo, F; Mantegna, R N; Eisler, Zoltan; Kertesz, Janos; Lillo, Fabrizio; Mantegna, Rosario N.

    2007-01-01

    We present a study of the order book data of the London Stock Exchange for five highly liquid stocks traded during the calendar year 2002. Specifically, we study the first passage time of order book prices needed to observe a prescribed price change "Delta", the time to fill (TTF) for executed limit orders and the time to cancel (TTC) for canceled ones. We find that the distribution of the first passage time decays asymptotically in time as a power law with an exponent "L_FPT ~ 1.5". The median of the same quantity scales as "Delta^1.6", which is different from the "Delta^2" behavior expected for Brownian motion. The quantities TTF, and TTC are also asymptotically power law distributed with exponents "L_TTF = 1.8-2.2" and "L_TTC = 1.9-2.4", respectively. For the medians of the time to fill we observe a scaling proportional to "Delta^1.4". We outline a simple model, which assumes that prices are characterized by the empirically observed distribution of the first passage time and orders are canceled randomly wi...

  6. Assessment of Tumor Cells in a Mouse Model of Diffuse Infiltrative Glioma by Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Kuniaki Tanahashi

    2014-01-01

    Full Text Available Glioma of infiltrative nature is challenging for surgeons to achieve tumor-specific and maximal resection. Raman spectroscopy provides structural information on the targeted materials as vibrational shifts. We utilized Raman spectroscopy to distinguish invasive tumors from normal tissues. Spectra obtained from replication-competent avian sarcoma-(RCAS- based infiltrative glioma cells and glioma tissues (resembling low-grade human glioma were compared with those obtained from normal mouse astrocytes and normal tissues. In cell analysis, the spectra at 950–1000, 1030, 1050–1100, 1120–1130, 1120–1200, 1200–1300, 1300–1350, and 1450 cm−1 were significantly higher in infiltrative glioma cells than in normal astrocytes. In brain tissue analysis, the spectra at 1030, 1050–1100, and 1200–1300 cm−1 were significantly higher in infiltrative glioma tissues than in normal brain tissues. These spectra reflect the structures of proteins, lipids, and DNA content. The sensitivity and specificity to predict glioma cells by distinguishing normal cells were 98.3% and 75.0%, respectively. Principal component analysis elucidated the significance of spectral difference between tumor tissues and normal tissues. It is possible to distinguish invasive tumors from normal tissues by using Raman spectroscopy.

  7. 2D Coherent Charge Transport in Highly Ordered Conducting Polymers Doped by Solid State Diffusion

    OpenAIRE

    Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-ichi; Sirringhaus, Henning

    2016-01-01

    This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by the Nature Publishing Group. Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially sepa...

  8. A second order anti-diffusive Lagrange-remap scheme for two-component flows

    Directory of Open Access Journals (Sweden)

    Lagoutière Frédéric

    2011-11-01

    Full Text Available We build a non-dissipative second order algorithm for the approximate resolution of the one-dimensional Euler system of compressible gas dynamics with two components. The considered model was proposed in [1]. The algorithm is based on [8] which deals with a non-dissipative first order resolution in Lagrange-remap formalism. In the present paper we describe, in the same framework, an algorithm that is second order accurate in time and space, and that preserves sharp interfaces. Numerical results reported at the end of the paper are very encouraging, showing the interest of the second order accuracy for genuinely non-linear waves. Nous construisons un algorithme d’ordre deux et non dissipatif pour la résolution approchée des équations d’Euler de la dynamique des gaz compressibles à deux constituants en dimension un. Le modèle que nous considérons est celui à cinq équations proposé et analysé dans [1]. L’algorithme est basé sur [8] qui proposait une résolution approchée à l’ordre un et non dissipative au moyen d’un splitting de type Lagrange-projection. Dans le présent article, nous décrivons, dans le même formalisme, un algorithme d’ordre deux en temps et en espace, qui préserve des interfaces « parfaites » entre les constituants. Les résultats numériques rapportés à la fin de l’article sont très encourageants ; ils montrent clairement les avantages d’un schéma d’ordre deux pour les ondes vraiment non linéaires.

  9. Quantum dynamics of adsorbed H2 in the microporous framework MOF-5 analyzed using diffuse reflectance infrared spectroscopy

    Science.gov (United States)

    Fitzgerald, S. A.; Allen, K.; Landerman, P.; Hopkins, J.; Matters, J.; Myers, R.; Rowsell, J. L. C.

    2008-06-01

    Diffuse reflectance infrared spectroscopy is used to measure the quantum dynamics of molecular hydrogen adsorbed in the microporous material MOF-5. Low-temperature spectra reveal at least three distinct binding sites. The induced redshifts in the vibrational mode frequencies allow the estimation of site-specific binding energies ranging from 2.5 to 4 kJ/mol. Splittings in the rovibrational sidebands are consistent with the existing theories and indicate that H2 is relatively freely rotating even at temperatures as low as 10 K. Ortho to para conversion of the adsorbed H2 is observed to occur over the course of several hours. A translational sideband of 84cm-1 arises from the center-of-mass motion of H2 at the primary adsorption site and indicates that the zero-point energy is a substantial fraction of the binding energy of this site.

  10. Quantitative evaluation of multiple adulterants in roasted coffee by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and chemometrics.

    Science.gov (United States)

    Reis, Nádia; Franca, Adriana S; Oliveira, Leandro S

    2013-10-15

    The current study presents an application of Diffuse Reflectance Infrared Fourier Transform Spectroscopy for detection and quantification of fraudulent addition of commonly employed adulterants (spent coffee grounds, coffee husks, roasted corn and roasted barley) to roasted and ground coffee. Roasted coffee samples were intentionally blended with the adulterants (pure and mixed), with total adulteration levels ranging from 1% to 66% w/w. Partial Least Squares Regression (PLS) was used to relate the processed spectra to the mass fraction of adulterants and the model obtained provided reliable predictions of adulterations at levels as low as 1% w/w. A robust methodology was implemented that included the detection of outliers. High correlation coefficients (0.99 for calibration; 0.98 for validation) coupled with low degrees of error (1.23% for calibration; 2.67% for validation) confirmed that DRIFTS can be a valuable analytical tool for detection and quantification of adulteration in ground, roasted coffee.

  11. An arbitrary order diffusion algorithm for solving Schrödinger equations

    Science.gov (United States)

    Chin, S. A.; Janecek, S.; Krotscheck, E.

    2009-09-01

    We describe a simple and rapidly converging code for solving the local Schrödinger equation in one, two, and three dimensions that is particularly suited for parallel computing environments. Our algorithm uses high-order imaginary time propagators to project out the eigenfunctions. A recently developed multi-product, operator splitting method permits, in principle, convergence to any even order of the time step. We review briefly the theory behind the method and discuss strategies for assessing convergence and accuracy. A forward time step, single product fourth-order factorization of the imaginary time evolution operator can also be used. Our code requires one user defined function which specifies the local external potential. We describe the definition of this function as well as input and output functionalities and convergence criteria. Compared to our previously published code [Computer Physics Communications 178 (2008) 835], the new algorithms can converge at a rate that is only limited by machine precision. Program summaryProgram title: ndsch Catalogue identifier: AEDR_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDR_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 9282 No. of bytes in distributed program, including test data, etc.: 77 824 Distribution format: tar.gz Programming language: Fortran 90 Computer: Tested on x86, amd64, and Itanium2 architectures. Should run on any architecture providing a Fortran 90 compiler Operating system: So far tested under UNIX/Linux, Mac OSX and Windows. Any OS with a Fortran 90 compiler available should suffice RAM: 2 MB to 16 GB, depending on system size Classification: 6.10 External routines: FFTW3 ( http://www.fftw.org/), Lapack ( http://www.netlib.org/lapack/) Nature of problem: Numerical calculation of the

  12. NMR diffusion spectroscopy for the characterization of multicomponent hydrogen-bonded assemblies in solution

    NARCIS (Netherlands)

    Timmerman, Peter; Weidmann, Jean-Luc; Jolliffe, Katrina A.; Prins, Leonard J.; Reinhoudt, David N.; Shinkai, Seiji; Frish, Limor; Cohen, Yoram

    2000-01-01

    NMR diffusion measurements on 10 different multicomponent hydrogen-bonded assemblies, viz. the three single rosettes SR1–SR3 ( 13· 2a3, 13· 2b3, 13· 2c3) the double rosettes DR1–DR5 ( 3a3· 2a6, 3b3· 2b6, 3c3· 2a6, 3d3· 2a6, 3e3· 2a6), and DR6 ( 4a3· 16), and the tetrarosette TR ( 53· 2a12) are descr

  13. VOLTAMMETRY AND ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF MEMBRANE SYSTEMS UNDER STABILIZED DIFFUSION LAYER THICKNESS

    Directory of Open Access Journals (Sweden)

    Sharafan M. V.

    2015-11-01

    Full Text Available The current-voltage characteristics and the number of effective ion transfer, as well as the frequency spectrum of the electrochemical impedance of multilayer ion-exchange membranes in a stable and controllable thickness of the diffusion layer were measured, using the of rotating membrane disk complex. The article presents a comparative analysis of the frequency spectra of the electrochemical impedance of the source and a surface-modified monopolar anion exchange membranes in 0.01 M sodium chloride was made. The process of water molecules dissociation at current densities above the limiting one in 0.01 M sodium chloride solution was studied in detail

  14. Linear and third- and fifth-order nonlinear spectroscopies of a charge transfer system coupled to an underdamped vibration

    Energy Technology Data Exchange (ETDEWEB)

    Dijkstra, Arend G., E-mail: arend.dijkstra@mpsd.mpg.de, E-mail: tanimura@kuchem.kyoto-u.ac.jp [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); Tanimura, Yoshitaka, E-mail: arend.dijkstra@mpsd.mpg.de, E-mail: tanimura@kuchem.kyoto-u.ac.jp [Department of Chemistry, Kyoto University, Kyoto (Japan)

    2015-06-07

    We study hole, electron, and exciton transports in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole, and exciton transfers can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional (2D) spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states during two different time periods.

  15. Linear and third- and fifth-order nonlinear spectroscopies of a charge transfer system coupled to an underdamped vibration.

    Science.gov (United States)

    Dijkstra, Arend G; Tanimura, Yoshitaka

    2015-06-01

    We study hole, electron, and exciton transports in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole, and exciton transfers can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional (2D) spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states during two different time periods.

  16. Comparison of organic phantom recipes and characterization by time-resolved diffuse optical spectroscopy

    Science.gov (United States)

    Quarto, G.; Pifferi, A.; Bargigia, I.; Farina, A.; Cubeddu, R.; Taroni, P.

    2013-06-01

    Three recipes for tissue constituent-equivalent phantoms of water and lipids are presented. Nature phantoms are made using no emulsifying agent, but just a professional disperser, instead Agar and Triton phantoms are made using agar or Triton X-100, respectively, as agents to emulsify water and lipids. Different water-to-lipid ratios ranging from 30 to 70 percent by mass are proposed and tested. Optical characterization by time-resolved spectroscopy was performed in terms of optical properties, homogeneity, reproducibility and composition retrieval.

  17. Retrieving the optical parameters of biological tissues using diffuse reflectance spectroscopy and Fourier series expansions. I. theory and application.

    Science.gov (United States)

    Muñoz Morales, Aarón A; Vázquez Y Montiel, Sergio

    2012-10-01

    The determination of optical parameters of biological tissues is essential for the application of optical techniques in the diagnosis and treatment of diseases. Diffuse Reflection Spectroscopy is a widely used technique to analyze the optical characteristics of biological tissues. In this paper we show that by using diffuse reflectance spectra and a new mathematical model we can retrieve the optical parameters by applying an adjustment of the data with nonlinear least squares. In our model we represent the spectra using a Fourier series expansion finding mathematical relations between the polynomial coefficients and the optical parameters. In this first paper we use spectra generated by the Monte Carlo Multilayered Technique to simulate the propagation of photons in turbid media. Using these spectra we determine the behavior of Fourier series coefficients when varying the optical parameters of the medium under study. With this procedure we find mathematical relations between Fourier series coefficients and optical parameters. Finally, the results show that our method can retrieve the optical parameters of biological tissues with accuracy that is adequate for medical applications.

  18. Optical detection of breast tumors: a comparison of diagnostic performance of autofluorescence, diffuse reflectance, and Raman spectroscopy

    Science.gov (United States)

    Majumder, Shovan K.; Keller, Matthew D.; Mahadevan-Jansen, Anita

    2007-02-01

    We report the results of a comparative evaluation of the diagnostic capabilities of autofluorescence, diffuse reflectance, and Raman spectroscopic approaches in differentiating the various types of breast tumors from normal breast tissues. Optical spectra (n=293) were acquired ex-vivo from a total of 75 breast tissue samples belonging to six distinct histopathologic categories: invasive ductal carcinoma, lobular carcinoma, ductal carcinoma in-situ, fibroadenoma, other benign tumors, and normal breast tissue. Autofluorescence, diffuse reflectance, and Raman spectra were measured from the same locations of a given tissue sample. A probability based multivariate statistical algorithm capable of direct multiclass classification was developed to analyze the diagnostic content of the optical spectra measured from the same set of breast tissue sites with these different techniques. The algorithm uses the theory of nonlinear Maximum Representation and Discrimination Feature (MRDF) for feature extraction, and the theory of Sparse Multinomial Logistic Regression (SMLR) for classification. The results of discrimination analyses reveal that the performance of Raman spectroscopy is superior to that of all others in classifying the breast tissues into respective histopathologic categories. The best classification accuracy was observed to be ~96%, 86%, 94%, 98%, 85%, and 100% for invasive ductal carcinoma, lobular carcinoma, ductal carcinoma in-situ, fibroadenoma, benign tumors and normal breast tissues, respectively, on the basis of leave-one-out cross validation, with the overall accuracy being ~97%.

  19. Diffuse reflectance spectroscopy from 400-1600 nm to evaluate tumor resection margins during head and neck surgery (Conference Presentation)

    Science.gov (United States)

    Brouwer de Koning, Susan G.; Baltussen, E. J. M.; Karakullukcu, M. Baris; Smit, L.; van Veen, R. L. P.; Hendriks, Benno H. W.; Sterenborg, H. J. C. M.; Ruers, Theo J. M.

    2017-02-01

    This ex vivo study evaluates the feasibility of diffuse reflectance spectroscopy (DRS) for discriminating tumor from healthy oral tissue, with the aim to develop a technique that can be used to determine a complete excision of tumor through intraoperative margin assessment. DRS spectra were acquired on fresh surgical specimens from patients with an oral squamous cell carcinoma. The spectra represent a measure of diffuse light reflectance (wavelength range of 400-1600 nm), detected after illuminating tissue with a source fiber at 1.0 and 2.0 mm distances from a detection fiber. Spectra were obtained from 23 locations of tumor tissue and 16 locations of healthy muscle tissue. Biopsies were taken from all measured locations to facilitate an optimal correlation between spectra and pathological information. The area under the spectrum was used as a parameter to classify spectra of tumor and healthy tissue. Next, a receiver operating characteristics (ROC) analysis was performed to provide the area under the receiver operating curve (AUROC) as a measure for discriminative power. The area under the spectrum between 650 and 750 nm was used in the ROC analysis and provided AUROC values of 0.99 and 0.97, for distances of 1 mm and 2 mm between source and detector fiber, respectively. DRS can discriminate tumor from healthy oral tissue in an ex vivo setting. More specimens are needed to further evaluate this technique with component analyses and classification methods, prior to in vivo patient measurements.

  20. Proton MR Spectroscopy and Diffusion MR Imaging Monitoring to Predict Tumor Response to Interstitial Photodynamic Therapy for Glioblastoma

    Science.gov (United States)

    Toussaint, Magali; Pinel, Sophie; Auger, Florent; Durieux, Nicolas; Thomassin, Magalie; Thomas, Eloise; Moussaron, Albert; Meng, Dominique; Plénat, François; Amouroux, Marine; Bastogne, Thierry; Frochot, Céline; Tillement, Olivier; Lux, François; Barberi-Heyob, Muriel

    2017-01-01

    Despite recent progress in conventional therapeutic approaches, the vast majority of glioblastoma recur locally, indicating that a more aggressive local therapy is required. Interstitial photodynamic therapy (iPDT) appears as a very promising and complementary approach to conventional therapies. However, an optimal fractionation scheme for iPDT remains the indispensable requirement. To achieve that major goal, we suggested following iPDT tumor response by a non-invasive imaging monitoring. Nude rats bearing intracranial glioblastoma U87MG xenografts were treated by iPDT, just after intravenous injection of AGuIX® nanoparticles, encapsulating PDT and imaging agents. Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) allowed us an original longitudinal follow-up of post-treatment effects to discriminate early predictive markers. We successfully used conventional MRI, T2 star (T2*), Diffusion Weighted Imaging (DWI) and MRS to extract relevant profiles on tissue cytoarchitectural alterations, local vascular disruption and metabolic information on brain tumor biology, achieving earlier assessment of tumor response. From one day post-iPDT, DWI and MRS allowed us to identify promising markers such as the Apparent Diffusion Coefficient (ADC) values, lipids, choline and myoInositol levels that led us to distinguish iPDT responders from non-responders. All these responses give us warning signs well before the tumor escapes and that the growth would be appreciated. PMID:28255341

  1. Observation of chest tumor using diffuse optical spectroscopy: time-varying Indocyanine green concentration in rabbit model

    Science.gov (United States)

    Kim, Yikeun; Kim, Sehun; Kim, Sungwon; Lee, Haeyoung; Oak, Chulho; Ahn, Yeh-Chan

    2017-02-01

    This experiment was conducted by using the diffuse optical spectroscopy based on near-infrared light. The near-infrared light in the water window was used to see the change of molecular concentration in the living tissue. The experiment subject was New Zealand rabbits weighing 3 +/- 0.3 kg. VX2 tumor cells were injected into the inside of the chest wall of rabbits. The concentration of indocyanine green (ICG) has been observed once every three days, after the size of the pleural tumor grew up over 1cm. We used five different wavelengths (732, 758, 805, 840, and 880 nm) with known ICG spectrum. The distance between light source and detector probes was fixed by 1 cm. The probes were placed on the skin right above the tumor with an aid of laparoscope. ICG was injected into rabbits via ear vein. The diffused light was measured through the tumor with time course using a spectrometer. These measured data enabled us to observe the change of ICG concentration in real time with respect to the baseline without ICG. ICG was present longer in tumor compared to normal tissue. This phenomenon is thought to be due to the excessive angiogenesis in the tumor tissue. Since this method can be applied to other cases easily, it is thought that there is a possibility of cancer screening with less cost and simple equipment.

  2. Use of diffuse optical spectroscopy to monitor muscle and brain oxygenation dynamics during isometric and isokinetic exercise

    Science.gov (United States)

    Ganesan, Goutham; Cotter, Joshua; Reuland, Warren; Warren, Robert V.; Mirzaei Zarandi, Soroush M.; Cerussi, Albert E.; Tromberg, Bruce J.; Galassetti, Pietro

    2013-03-01

    The use of near-infrared time-resolved spectroscopy (TRS-20, Hamamatsu Corporation) in two resistance type exercise applications in human subjects is described. First, using isometric flexion of the biceps, we compared the magnitude and relevance of tissue hemoglobin concentration and oxygen saturation (stO2) changes when assuming constant scattering versus continuous measurement of reduced scattering coefficients at three wavelengths. It was found that the assumption of constant scattering resulted in significant errors in hemoglobin concentration assessment during sustained isometric contractions. Secondly, we tested the effect of blood flow restriction (BFR) on oxygenation in a muscle (vastus medialis oblique, VMO) and in the prefrontal cortex (PFC) of the brain. The BFR training technique resulted in considerably more fatigability in subjects, and correlated with reduced muscle stO2 between sets of exertion. Additionally, exercise with BFR resulted in greater PFC deoxygenation than a condition with equivalent work performance but no BFR. These experiments demonstrate novel applications for diffuse optical spectroscopy in strength testing and targeted muscle rehabilitation.

  3. Benefits of applying combined diffuse reflectance FTIR spectroscopy and principal component analysis for the study of blue tempera historical painting.

    Science.gov (United States)

    Navas, Natalia; Romero-Pastor, Julia; Manzano, Eloisa; Cardell, Carolina

    2008-12-23

    This paper explores the application of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to the examination of historic blue pigments and blue tempera paintings commonly found on works of art. The discussion is mainly focused on the practical benefits of using this technique joined to principal component analysis (PCA), a powerful multivariate analysis tool. Thanks to the study of several replica samples that contain either pure blue pigments (azurite, lapis lazuli and smalt), or pure binder (rabbit glue) and mixtures of each of the pigments with the binder (tempera samples), different aspects of these benefits are highlighted. Comparative results of direct spectra and multivariate analysis using transmittance-Fourier transform infrared spectroscopy (T-FTIR) are discussed throughout this study. Results showed an excellent ability of PCA on DRIFT spectra for discriminating replica samples according to differing composition. Several IR regions were tested with this aim; the fingerprint IR region exhibited the best ability for successfully clustering the samples. The presence of the binder was also discriminated. Only using this approach it was possible to completely separate all the studied replica samples. This demonstrates the potential benefits of this approach in identifying historical pigments and binders for conservation and restoration purposes in the field of Cultural Heritage.

  4. Non-contact assessment of COD and turbidity concentrations in water using diffuse reflectance UV-Vis spectroscopy.

    Science.gov (United States)

    Agustsson, Jon; Akermann, Oliver; Barry, D Andrew; Rossi, Luca

    2014-08-01

    Water contamination is an important environmental concern underlining the need for reliable real-time information on contaminant concentrations in natural waters. Here, a new non-contact UV-Vis spectroscopic approach for monitoring contaminants in water, and especially wastewater, is proposed. Diffuse reflectance UV-Vis spectroscopy was applied to measure simultaneously the chemical oxygen demand (COD) and turbidity (TUR) concentrations in water. The measurements were carried out in the wavelength range from 200-1100 nm. The measured spectra were analysed using partial-least-squares (PLS) regression. The correlation coefficient between the measured and the reference concentrations of COD and TUR in the water samples were R(2) = 0.85 and 0.96, respectively. These results highlight the potential of non-contact UV-Vis spectroscopy for the assessment of water contamination. A system built on the concept would be able to monitor wastewater pollution continuously, without the need for laborious sample collection and subsequent laboratory analysis. Furthermore, since no parts of the system are in contact with the wastewater stream the need for maintenance is minimised.

  5. Polyimide analysis using diffuse reflectance-FTIR. [Fourier Transform IR Spectroscopy

    Science.gov (United States)

    Young, P. R.; Chang, A. C.

    1985-01-01

    The thermal imidization of a number of polyimide precursors in the form of powders, films, and prepregs was examined by an in situ diffuse reflectance-FTIR technique where infrared spectra were determined while the material was being heated. An analysis of these spectra revealed that, with the exception of one water soluble adhesive, each precursor developed an anhydride band around 1850 cm/cu during imidization. This band diminished in intensity during final stages of cure. Efforts were made to quantify the amount of anhydride in several samples. Evidence obtained could be interpreted to mean that poly(amic acid) resins undergo an initial reduction in molecular weight during imidization before recombining to achieve their ultimate molecular weights as polyimides. Several reports in the literature are cited to support this interpretation. This report serves both to document anhydride formation during imidization and to increase our fundamental understanding of how polyimides cure.

  6. Method of measuring blood oxygenation based on spectroscopy of diffusely scattered light

    Science.gov (United States)

    Kleshnin, M. S.; Orlova, A. G.; Kirillin, M. Yu.; Golubyatnikov, G. Yu.; Turchin, I. V.

    2017-05-01

    A new approach to the measurement of blood oxygenation is developed and implemented, based on an original two-step algorithm reconstructing the relative concentration of biological chromophores (haemoglobin, water, lipids) from the measured spectra of diffusely scattered light at different distances from the radiation source. The numerical experiments and approbation of the proposed approach using a biological phantom have shown the high accuracy of the reconstruction of optical properties of the object in question, as well as the possibility of correct calculation of the haemoglobin oxygenation in the presence of additive noises without calibration of the measuring device. The results of the experimental studies in animals agree with the previously published results obtained by other research groups and demonstrate the possibility of applying the developed method to the monitoring of blood oxygenation in tumour tissues.

  7. Diffusion-Oscillatory Dynamics in Liquid Water on Data of Dielectric Spectroscopy

    CERN Document Server

    Volkov, A A; Volkov, A A; Sysoev, N N

    2016-01-01

    When analyzing the broadband absorption spectrum of liquid water (10^10 - 10^13 Hz), we find its relaxation-resonance features to be an indication of Frenkel's translation-oscillation motion of particles, which is fundamentally inherent to liquids. We have developed a model of water structure, of which the dynamics is due to diffusion of particles, neutral H2O molecules and H3O+ and OH- ions - with their periodic localizations and mutual transformations. This model establishes for the first time a link between the dc conductivity, the Debye and the high frequency sub-Debye relaxations and the infrared absorption peak at 180 cm-1. The model reveals the characteristic times of the relaxations, 50 ps and 3 ps, as the lifetimes of water molecules and water ions, respectively. The model sheds light on the anomalous mobility of a proton and casts doubt on the long lifetime of a water molecule, 10 hours, commonly associated with autoionization.

  8. Noninvasive assessment of breast cancer risk using time-resolved diffuse optical spectroscopy

    Science.gov (United States)

    Taroni, Paola; Pifferi, Antonio; Quarto, Giovanna; Spinelli, Lorenzo; Torricelli, Alessandro; Abbate, Francesca; Villa, Anna; Balestreri, Nicola; Menna, Simona; Cassano, Enrico; Cubeddu, Rinaldo

    2010-11-01

    Breast density is a recognized strong and independent risk factor for breast cancer. We propose the use of time-resolved transmittance spectroscopy to estimate breast tissue density and potentially provide even more direct information on breast cancer risk. Time-resolved optical mammography at seven wavelengths (635 to 1060 nm) is performed on 49 subjects. Average information on breast tissue of each subject is obtained on oxy- and deoxyhemoglobin, water, lipids, and collagen content, as well as scattering amplitude and power. All parameters, except for blood volume and oxygenation, correlate with mammographic breast density, even if not to the same extent. A synthetic optical index proves to be quite effective in separating different breast density categories. Finally, the estimate of collagen content as a more direct means for the assessment of breast cancer risk is discussed.

  9. Systematic optimization of MRI guided near infrared diffuse optical spectroscopy in breast

    Science.gov (United States)

    Zhao, Yan; Mastanduno, Michael A.; Jiang, Shudong; El-Ghussein, Fadi; Xu, Junqing; Gui, Jiang; Pogue, Brian W.; Paulsen, Keith D.

    2015-03-01

    A hybrid frequency domain (FD)-continuous wave (CW) MRI/NIRS system was validated in a clinical trial involving patients with at least ACR 4 radiologic findings in Xi'an, China. In this study, MRI guided nonlinear iterative reconstruction of near-infrared spectroscopy (NIRS) images with limited phase data is investigated. In addition, a systematic optimization of the system hardware design has been conducted as well. We are able to get less than 3% variation in tumor contrast to the surrounding normal tissue, by reducing the number of FD detectors from 16 to 6, showing the potential of reducing the FD detectors. Furthermore, a lookup table of the scattering properties has been made by averaging four MRI-identified breast density groups. By using this look-up table for the patient with the noisy phase data, similar AUCs and p-values are achieved for differentiating the malignant from benign patients.

  10. Studying the universality of field induced tunnel ionization times via high-order harmonic spectroscopy

    CERN Document Server

    Soifer, Hadas; Negro, Matteo; Devetta, Michele; Faccialà, Davide; Vozzi, Caterina; de Silvestri, Sandro; Stagira, Salvatore; Dudovich, Nirit

    2014-01-01

    High-harmonics generation spectroscopy is a promising tool for resolving electron dynamics and structure in atomic and molecular systems. This scheme, commonly described by the strong field approximation, requires a deep insight into the basic mechanism that leads to the harmonics generation. Recently, we have demonstrated the ability to resolve the first stage of the process -- field induced tunnel ionization -- by adding a weak perturbation to the strong fundamental field. Here we generalize this approach and show that the assumptions behind the strong field approximation are valid over a wide range of tunnel ionization conditions. Performing a systematic study -- modifying the fundamental wavelength, intensity and atomic system -- we observed a good agreement with quantum path analysis over a range of Keldysh parameters. The generality of this scheme opens new perspectives in high harmonics spectroscopy, holding the potential of probing large, complex molecular systems.

  11. Brain intracellular metabolites are freely diffusing along cell fibers in grey and white matter, as measured by diffusion-weighted MR spectroscopy in the human brain at 7 T.

    Science.gov (United States)

    Najac, Chloé; Branzoli, Francesca; Ronen, Itamar; Valette, Julien

    2016-04-01

    Due to the specific compartmentation of brain metabolites, diffusion-weighted magnetic resonance spectroscopy opens unique insight into neuronal and astrocytic microstructures. The apparent diffusion coefficient (ADC) of brain metabolites depends on various intracellular parameters including cytosol viscosity and molecular crowding. When diffusion time (t d) is long enough, the size and geometry of the compartment in which the metabolites diffuse strongly influence metabolites ADC. In a previous study, performed in the macaque brain, we measured neuronal and astrocytic metabolites ADC at long t d (from 86 to 1,011 ms) in a large voxel enclosing an equal proportion of white and grey matter. We showed that metabolites apparently diffuse freely along the axis of dendrites, axons and astrocytic processes. To assess potential differences between these two tissue types, here we measured for the first time in the Human brain the t d-dependency of metabolites trace/3 ADC at 7 teslas using a localized diffusion-weighted STEAM sequence, in parietal and occipital voxels, respectively, containing mainly white and grey matter. We show that, in both tissues and over the observed timescale (t d varying from 92 to 712 ms) metabolite ADC reaches a non-zero plateau, suggesting that metabolites are not confined inside subcellular regions such as cell bodies, or inside subcellular compartments such as organelles, but are rather free to diffuse in the whole fiber-like structure of neurons and astrocytes. Beyond the fundamental insights into intracellular compartmentation of metabolites, this work also provides a new framework for interpreting results of neuroimaging techniques based on molecular diffusion, such as diffusion-weighted magnetic resonance spectroscopy and imaging.

  12. Spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules.......This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules....

  13. The diffusion dynamics of PEGylated liposomes in the intact vitreous of the ex vivo porcine eye: A fluorescence correlation spectroscopy and biodistribution study

    DEFF Research Database (Denmark)

    Eriksen, Anne Zebitz; Brewer, Jonathan; Andresen, Thomas Lars

    2017-01-01

    correlation spectroscopy (FCS) to determine liposome diffusion coefficients in the intact vitreous (DVit) of ex vivo porcine eyes using a modified Miyake-Apple technique to minimize the disruption of the vitreous fine structure. We chose to investigate whether the zeta potential of polyethylene glycol...

  14. Acute necrotizing encephalopathy secondary to diphtheria, tetanus toxoid and whole-cell pertussis vaccination: diffusion-weighted imaging and proton MR spectroscopy findings

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Hale; Ozgul, Esra; Agildere, Ahmet Muhtesem [Baskent University Hospital, Department of Radiology, Ankara (Turkey)

    2010-07-15

    We present a previously healthy 6-month-old boy who was admitted to our hospital with lethargy, hypotonia and focal clonic seizures 6 days following diptheria, tetanus toxoid and whole-cell pertussis vaccination. A diagnosis of acute necrotising encephalopathy was made with the aid of MRI, including diffusion-weighted imaging and proton MR spectroscopy. (orig.)

  15. Diffuse reflectance spectroscopy of neptunium ions in polycrystalline ceramics designed for immobilization of HLW

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yingjie [Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)], E-mail: yzx@ansto.gov.au; Vance, Eric R.; Begg, Bruce D.; Li Huijun [Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)

    2007-10-11

    Diffuse reflectance spectra at room temperature have been collected on polycrystalline perovskite (CaTiO{sub 3}), zirconolite (CaZrTi{sub 2}O{sub 7}) and thorutite (ThTi{sub 2}O{sub 6}) samples doped with Np. The Np species give rise to a number of broad, unresolved intraconfigurational f-f electronic transition bands in the near-infrared and visible spectral regions. Both Np{sup 3+} and Np{sup 4+} can substitute in the Ca site of perovskite by the appropriate choice of charge compensation and sintering atmosphere. No detectable spectral differences were observed when Np{sup 4+} was targeted towards either the Ca or Zr sites in zirconolite. Np{sup 4+} but not Np{sup 5+} can be incorporated in the Th site of thorutite by sintering in air. Even in the most dilute [{<=} 0.03 formula units (f.u.)] Np{sup 4+} samples of the different titanates studied, there was only very approximate agreement with the Kubelka-Munk law.

  16. Microcirculation assessment using an individualized model for diffuse reflectance spectroscopy and conventional laser Doppler flowmetry

    Science.gov (United States)

    Strömberg, Tomas; Karlsson, Hanna; Fredriksson, Ingemar; Nyström, Fredrik H.; Larsson, Marcus

    2014-05-01

    Microvascular assessment would benefit from co-registration of blood flow and hemoglobin oxygenation dynamics during stimulus response tests. We used a fiber-optic probe for simultaneous recording of white light diffuse reflectance (DRS; 475-850 nm) and laser Doppler flowmetry (LDF; 780 nm) spectra at two source-detector distances (0.4 and 1.2 mm). An inverse Monte Carlo algorithm, based on a multiparameter three-layer adaptive skin model, was used for analyzing DRS data. LDF spectra were conventionally processed for perfusion. The system was evaluated on volar forearm recordings of 33 healthy subjects during a 5-min systolic occlusion protocol. The calibration scheme and the optimal adaptive skin model fitted DRS spectra at both distances within 10%. During occlusion, perfusion decreased within 5 s while oxygenation decreased slowly (mean time constant 61 s dissociation of oxygen from hemoglobin). After occlusion release, perfusion and oxygenation increased within 3 s (inflow of oxygenized blood). The increased perfusion was due to increased blood tissue fraction and speed. The supranormal hemoglobin oxygenation indicates a blood flow in excess of metabolic demands. In conclusion, by integrating DRS and LDF in a fiber-optic probe, a powerful tool for assessment of blood flow and oxygenation in the same microvascular bed has been presented.

  17. A new numerical method for solving two-dimensional variable-order anomalous sub-diffusion equation

    Directory of Open Access Journals (Sweden)

    Jiang Wei

    2016-01-01

    Full Text Available The novelty and innovativeness of this paper are the combination of reproducing kernel theory and spline, this leads to a new simple but effective numerical method for solving variable-order anomalous sub-diffusion equation successfully. This combination overcomes the weaknesses of piecewise polynomials that can not be used to solve differential equations directly because of lack of the smoothness. Moreover, new bases of reproducing kernel spaces are constructed. On the other hand, the existence of any ε-approximate solution is proved and an effective method for obtaining the ε-approximate solution is established. A numerical example is given to show the accuracy and effectiveness of theoretical results.

  18. A SECOND ORDER CONTROL-VOLUME FINITE-ELEMENT LEAST-SQUARES STRATEGY FOR SIMULATING DIFFUSION IN STRONGLY ANISOTROPIC MEDIA

    Institute of Scientific and Technical Information of China (English)

    Jayantha Pasdunkorale A.; Ian W. Turner

    2005-01-01

    An unstructured mesh finite volume discretisation method for simulating diffusion in anisotropic media in two-dimensional space is discussed. This technique is considered as an extension of the fully implicit hybrid control-volume finite-element method and it retains the local continuity of the flux at the control volume faces. A least squares function reconstruction technique together with a new flux decomposition strategy is used to obtain an accurate flux approximation at the control volume face, ensuring that the overall accuracy of the spatial discretisation maintains second order. This paper highlights that the new technique coincides with the traditional shape function technique when the correction term is neglected and that it significantly increases the accuracy of the previous linear scheme on coarse meshes when applied to media that exhibit very strong to extreme anisotropy ratios. It is concluded that the method can be used on both regular and irregular meshes,and appears independent of the mesh quality.

  19. Nonideal diffusion effects and short-range ordering lead to higher aggregation rates in concentrated hard-sphere dispersions.

    Science.gov (United States)

    Kelkar, Aniruddha V; Franses, Elias I; Corti, David S

    2014-04-08

    Brownian aggregation in concentrated hard-sphere dispersions is studied using models and Brownian dynamics (BD) simulations. Two new theoretical models are presented and compared to several existing approaches and BD simulation results, which serve as benchmarks. The first new model is an improvement over an existing local density approximation (LDA)-based model. The other is based on the more rigorous Fundamental measure theory (FMT) applied to the "liquid-state" dynamic density-functional theory (DDFT). Both models provide significant improvements over the classical Smoluchowski model. The predictions of the new FM-DDFT-based model for aggregation kinetics are in excellent agreement with BD simulation results for dispersions with initial particle volume fractions, ϕ, up to 0.35 (close to the hard-sphere freezing transition at ϕ = 0.494). In contrast to previous approaches, the nonideal particle diffusion effects and the initial and time-dependent short-range ordering in concentrated dispersions due to entropic packing effects are explicitly considered here, in addition to the unsteady-state effects. The greater accuracy of the FM-DDFT-based model compared to that of the LDA-based models indicates that nonlocal contributions to particle diffusion (only accounted for in the former) play important roles in aggregation. At high concentrations, the FM-DDFT-based model predicts aggregation half-times and gelation times that are up to 2 orders of magnitude shorter than those of the Smoluchowski model. Moreover, the FM-DDFT-based model predicts asymmetric cluster-cluster aggregation rate constants, at least for short times. Overall, a rigorous mechanistic understanding of the enhancement of aggregation kinetics in concentrated dispersions is provided.

  20. MRI-Guided Diffuse Optical Spectroscopy of Malignant and Benign Breast Lesions

    Directory of Open Access Journals (Sweden)

    Vasilis Ntziachristos

    2002-01-01

    Full Text Available We present the clinical implementation of a novel hybrid system that combines magnetic resonance imaging (MRI and near-infrared (NIR optical measurements for the noninvasive study of breast cancer in vivo. Fourteen patients were studied with a MR-NIR prototype imager and spectrometer. A diffuse optical tomographic scheme employed the MR images as a priori information to implement an image-guided NIR localized spectroscopic scheme. All patients who entered the study also underwent gadolinium-enhanced MRI and biopsy so that the optical findings were crossvalidated with MR readings and histopathology. The technique quantified the oxy-and deoxyhemoglobin of five malignant and nine benign breast lesions in vivo. Breast cancers were found with decreased oxygen saturation and higher blood concentration than most benign lesions. The average hemoglobin concentration ([H] of cancers was 0.130±0.100 mM, and the average hemoglobin saturation (Y was 60±9% compared to [H]=0.018±0.005 mM and Y=69±6% of background tissue. Fibroadenomas exhibited high hemoglobin concentration [H]=0.060±0.010 mM and mild decrease in oxygen saturation Y=67±2%. Cysts and other normal lesions were easily differentiated based on intrinsic contrast information. This novel optical technology can be a significant add-on in MR examinations and can be used to characterize functional parameters of cancers with diagnostic and treatment prognosis potential. It is foreseen that the technique can play a major role in functional activation studies of brain and muscle as well.

  1. Functional imaging of neoadjuvant chemotherapy response in women with locally advanced breast cancer using diffuse optical spectroscopy.

    Science.gov (United States)

    Soliman, Hany; Yaffe, Martin J; Czarnota, Gregory J

    2009-01-01

    Functional imaging with tomographic near infrared diffuse optical spectroscopy (DOS) can quantitatively measure tissue parameters such as the concentration of deoxy-hemoglobin (Hb), oxy-hemoglobin (HbO2), percent water (%water), and scattering power (SP). The purpose of this study was to evaluate the correlation between DOS functional parameters with pathologic outcomes. Patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy or chemoradiotherapy were recruited to this study (n = 10). Five scans were conducted per patient: a baseline scan was taken up to 3 days prior to treatment and at 1 week, 4 weeks, 8 weeks, and after neoadjuvant treatment prior to surgery. At each scan the patient lay prone with the breast suspended between immobilization plates in optical coupling medium. Pulsed near-infrared laser light was used to scan the breast at four different wavelengths and data was used for tomographic reconstruction. Volume-of-interest (VOI) weighted tissue Hb, HbO2, %water, and SP corresponding to the tumour was calculated and compared to clinical and pathological response as determined from full mount mastectomy pathology. For all 10 patients the tumour-based VOI was significantly different than background tissue for all functional parameters (pOne patient initially had a poor clinical response to chemotherapy but after a change in chemotherapy had a good clinical and radiographic response. Responders and non-responders were significantly different for all of the functional parameters (pdrop in Hb, HbO2, %water, and SP from baseline to the 4-week scan was 70.4% (SD = 18.6), 66.5% (SD = 24.5), 59.6% (SD = 30.9), and 60.7% (SD = 29.2), respectively. In contrast, the 4 non-responders had a mean drop of 17.7% (SD = 9.8), 18.0% (SD = 20.8), 15.4% (SD = 11.7), and 12.6% (SD = 10.2), for Hb, HbO2, %water and SP, respectively. Functional imaging using tomographic diffuse optical spectroscopy parameters of Hb, HbO2, %water and SP could be used as

  2. Evaluation of MR spectroscopy and diffusion-weighted MRI in detecting bone marrow changes in postmenopausal women with osteoporosis

    Energy Technology Data Exchange (ETDEWEB)

    Tang, G.Y., E-mail: tgy17@126.co [Department of Radiology, Affiliated Tenth People' s Hospital of Tongji University, Shanghai 200072 (China); Lv, Z.W.; Tang, R.B.; Liu, Y.; Peng, Y.F.; Li, W.; Cheng, Y.S. [Department of Radiology, Affiliated Tenth People' s Hospital of Tongji University, Shanghai 200072 (China)

    2010-05-15

    Aim: To prospectively investigate the role of MR spectroscopy (MRS) and diffusion-weighted magnetic resonance imaging (DWI) in assessing vertebral marrow changes in postmenopausal women with osteoporosis. Materials and methods: Seventy-eight postmenopausal women (mean age 63.7 +- 3.5 years; range 55-81 years), who underwent dual-energy x-ray absorptiometry of the spine, were divided into three bone density groups (24 with normal, 25 with osteopaenic, and 29 with osteoporotic) based on T score. Both MRS and DWI of the L3 vertebral body were performed to calculate the marrow fat content and apparent diffusion coefficient (ADC). The results were compared between three groups and correlated with BMD. Results: Vertebral marrow fat content was significantly increased in the osteoporotic group (59.97 +- 5.78%), when compared with that of the osteopaenic group (53.04 +- 7.66%, p = 0.001) and the normal bone density group (48.79 +- 7.1%, p < 0.001). ADC values in the osteoporotic, osteopaenic, and normal bone density groups were 0.39 +- 0.02 x 10{sup -3} mm{sup 2}/s, 0.41 +- 0.02 x 10{sup -3} mm{sup 2}/s, and 0.47 +- 0.03 x 10{sup -3} mm{sup 2}/s, respectively, with statistically significant difference (P < 0.001). A statistically significant positive correlation between T scores and ADC existed (r = 0.835, p < 0.001). The vertebral marrow fat content was negatively correlated to the bone density (r = -0.639, p < 0.001) and to marrow ADC (r = -0.554, p < 0.001). Conclusion: The postmenopausal women with osteoporosis exhibited a corresponding increase in vertebral marrow fat content as the bone density decreased. Marrow fat content and ADC were related to the bone density. MRS and DWI are helpful in evaluating the bone marrow changes in postmenopausal women.

  3. Diffusion-weighted imaging-guided MR spectroscopy in breast lesions using readout-segmented echo-planar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Kun; Chai, Weimin; Zhan, Ying; Luo, Xianfu; Yan, Fuhua [Shanghai Jiao Tong University School of Medicine, Department of Radiology, Ruijin Hospital, Shanghai (China); Fu, Caixia [Siemens MRI Center, Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen (China); Shen, Kunwei [Shanghai Jiao Tong University School of Medicine, Comprehensive Breast Health Center, Ruijin Hospital, Shanghai (China)

    2016-06-15

    To investigate the feasibility and effectiveness of diffusion-weighted imaging (DWI)-guided magnetic resonance spectroscopy (MRS) using readout-segmented echo-planar imaging (RS-EPI) to characterise breast lesions. A total of 258 patients with 258 suspicious breast lesions larger than 1 cm in diameter were examined using DWI-guided, single-voxel MRS with RS-EPI. The mean total choline-containing compound (tCho) signal-to-noise ratio (SNR) and concentration were used for the interpretation of MRS data. T-tests, χ{sup 2}-tests, receiver operating characteristic (ROC) curve analyses and Pearson correlations were conducted for statistical analysis. Histologically, 183 lesions were malignant, and 75 lesions were benign. Both the mean tCho SNR and concentration of malignant lesions were higher than those of benign lesions (6.23 ± 3.30 AU/mL vs. 1.26 ± 1.75 AU/mL and 3.17 ± 2.03 mmol/kg vs. 0.86 ± 0.83 mmol/kg, respectively; P < 0.0001). For a tCho SNR of 2.0 AU/mL and a concentration of 1.76 mmol/kg, the corresponding areas under the ROC curves were 0.93 and 0.90, respectively. The mean tCho SNR and concentration negatively correlated with apparent diffusion coefficients calculated from RS-EPI, with correlation coefficients of -0.54 and -0.48, respectively. DWI-guided MRS using RS-EPI is feasible and accurate for characterising breast lesions. (orig.)

  4. Diffusion-weighted imaging and magnetic resonance spectroscopy of sporadic Creutzfeldt-Jakob disease: correlation with clinical course

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheolkyu [Seoul National University Bundang Hospital, Department of Radiology, Seoul National University College of Medicine, Seongnam-si (Korea, Republic of); Chang, YoungHee; Kim, SangYun [Seoul National University Bundang Hospital, Department of Neurology, Seoul National University College of Medicine, Seongnam-si (Korea, Republic of)

    2011-12-15

    Sporadic Creutzfeldt-Jakob disease (sCJD) is a fatal disease with variable clinical courses. The presence or absence of basal ganglia (BG) involvement has been reported to be associated with clinical course. We investigated the association of clinical course of sCJD with diffusion-weighted imaging (DWI) and MR spectroscopy (MRS) as well as BG involvement at early stage. DWI and single voxel proton MRS were performed in 14 patients with sCJD during the initial diagnostic workup. Apparent diffusion coefficient (ADC) and metabolites were measured in medial occipitoparietal cortices where large hyperintense DWI lesions were found in all patients. The presence or absence of BG involvement, ADC, N-acetylaspartate (NAA)/creatine (Cr) ratios, and choline (Cho)/Cr ratios were correlated with disease duration (i.e., the time from the symptom onset to death). The disease duration ranged from 2 to 31 months (median, 16). Hyperintense DWI lesions were observed bilaterally in both cortices and basal ganglia in eight patients and in cortices alone in six patients. Patients with BG involvement had shorter disease duration (median, 6.8 versus 20.5; p = 0.039) than those without and lower NAA/Cr ratios (median, 1.41 versus 2.03; p = 0.001). ADC and Cho/Cr ratios were not significantly different between the patients with BG involvement and those without. By multiple regression analysis, NAA/Cr ratios had the greatest correlation with the disease duration (p = 0.029). The disease duration of sCJD was variable. NAA/Cr ratios of the affected brain at the early stage of sCJD can be used as a useful parameter in predicting the clinical course. (orig.)

  5. [Study on nondestructive rapid identification method of foods containing trans-fatty acids using diffuse near infrared spectroscopy].

    Science.gov (United States)

    An, Xue-Song; Song, Chun-Feng; Yuan, Hong-Fu; Xie, Jin-Chun; Li, Xiao-Yu

    2013-11-01

    A rapid nondestructive method for identifying intact foods containing trans fatty acids (TFA) using diffuse near infrared spectroscopy (NIR) was proposed in the present paper. The diffuse Fourier transform near infrared (FT-NIR) spectra of intact samples were collected by fiber probe, and the reference data of TFA content were determined by Chinese standard method GB/T 22110-2008 (gas chromatography (GC) method). In this work, all the samples were classified into two categories: foods with TFA and foods without TFA according to the TFA content of the foods. The identification models were established by different supervised pattern recognition algorithms including partial least square discriminant analysis (PLSDA), support vector machine (SVM), soft independent modeling of class analogy (SIMCA) and K-nearest neighbor method (KNN) etc. The performances of the established models employing different algorithms, data pretreatments and wavelength bands were compared. The results show that PLSDA and SVM algorithms have the ability of identifying intact foods with TFA, and the performance of identification models established by PLSDA is better than that of SVM. The PLSDA models established by the wavelength bands of 4 138-4 428, 5 507-5 963 and 7 794-8 960 cm(-1) which were pretreated with pretreatment methods of auto scaling and second derivative have the best performance. The correct classification percentages of its calibration and validation set are 96.4% and 88%, respectively, which indicates that this method is feasible for the identification of foods with TFA. This NIR method above mentioned has the characteristics of rapidness, non-destruction and easy operation due to the elimination of sample pretreatment such as oil extraction and grinding, therefore it is very suitable for on-line and in-site detection application.

  6. Determination of the pigments present in a wallpaper of the middle nineteenth century: the combination of mid-diffuse reflectance and far infrared spectroscopies.

    Science.gov (United States)

    Arrizabalaga, Iker; Gómez-Laserna, Olivia; Aramendia, Julene; Arana, Gorka; Madariaga, Juan Manuel

    2014-04-24

    In this work the determination of the pigments present in a decorative wallpaper of the middle nineteenth century from the Santa Isabel factory (Vitoria-Gasteiz, Basque Country, Spain) has been performed by a combination of mid-Diffuse Reflectance Infrared Spectroscopy (DRIFT) and Far Infrared Spectroscopy (FIR) in transmission mode. The DRIFT is a powerful infrared technique that is not widely used in the analyses of artworks in spite of being especially adequate for powdered samples. In this mode, sample pretreatment is not required and the obtained spectra are easier to solve than those obtained in transmittance mode. Those pigments which are not active in the mid-infrared region may be determined easily by FIR. In the last decade, in the field of painted materials very few studies performed by far infrared spectroscopy and mid infrared spectroscopy in diffuse reflectance mode can be found. In most of them the researchers have used one of these techniques, but in no case the combination of both. As we demonstrate in this work, combining these two techniques a complete characterization of the wallpaper can be carried out. Small samples were collected from the wallpaper for the analysis of the rose, brown, yellow and blue colours. In this way, minium (Pb3O4), calcite (CaCO3), barium sulphate (BaSO4), prussian blue (Fe7C18N18), iron oxide yellow (α-FeOOH), vermillion (HgS) and carbon black pigment from organic origen were detected. Finally, the validation was carried out by XRF and Raman spectroscopy getting the same results as with the combination of diffuse reflectance infrared spectroscopy and far infrared spectroscopy.

  7. Development of a hybrid broadband NIRS/diffusion correlation spectroscopy system to monitor preterm brain injury (Conference Presentation)

    Science.gov (United States)

    Rajaram, Ajay; St. Lawrence, Keith; Diop, Mamadou

    2017-02-01

    In Canada, 8% of births occur prematurely. Preterm infants weighing less than 1500g are at a high risk of neurodevelopmental impairment: 5-10% develop major disabilities such as cerebral palsy and 40-50% show other cognitive and behavioural deficits. The brain is vulnerable to periods of low cerebral blood flow (CBF) that can impair energy metabolism and cause tissue damage. There is, therefore, a need for an efficient neuromonitoring system to alert the neonatal intensive care team to clinically significant changes in CBF and metabolism, before injury occurs. Optical technologies offer safe, non-invasive, and cost-effective methods for neuromonitoring. Cerebral oxygen saturation (ScO2) can be measured by exploiting the absorption properties of hemoglobin though Near-Infrared Spectroscopy (NIRS), and Diffuse Correlation Spectroscopy (DCS) can monitor CBF by tracking red blood cells. These measures can be combined to describe metabolism, a key indicator of tissue viability. In this study we present the development and testing of a hybrid broadband NIRS/DCS neuromonitor. This system is novel in its ability to simultaneously acquire broadband NIRS and DCS signals, providing a truly real-time measure of metabolism. Narrow bandpass and notch filters have been incorporated to diminish light contamination between the two modalities, preferentially filtering out each source from the opposing detector, allowing for an accurate measure of ScO2, CBF, and metabolism. With a broadband NIRS/DCS system, a real-time measure of CBF and metabolism within the developing brain can aid clinicians in monitoring events that precede brain injury, ultimately leading to better clinical outcomes.

  8. Diffuse reflectance spectroscopy for field-scale assessment of winter wheat yield

    Science.gov (United States)

    Šestak, Ivana; Mesić, Milan; Zgorelec, Željka; Perčin, Aleksandra

    2017-04-01

    The objective was to evaluate the ability of visible and near infrared spectroscopy to predict winter wheat grain yield, and to compare different prediction models according to the spatial variability. Research was conducted on experimental field in Western Pannonian subregion of Croatia. Reflectance measurements (350-1050 nm) were acquired from winter wheat flag leaves grown under nine mineral N fertilization treatments ranging from 0 to 300 kg N ha-1, during the stem extension stage of the year 2010. Linear statistical models (MLR - multiple linear regression, PLSR - partial least squares regression) and non-linear pattern analysis (ANN - artificial neural networks) were generated to estimate grain yield, based on the first derivative of reflectance in form of principal components (PC) and vegetation indices (VI). ANN models were the most efficient in capturing the complex link between yield and leaf reflectance spectra (train and test dataset with r = 0.95 and r = 0.92, RMSEC = 2.57 dt ha-1 and RMSEP = 4.41 dt ha-1, respectively) compared to corresponding VIs, MLR and PLSR models. Performance of the 8 factor PLSR model indicated the highest consistency due to the small difference between RMSEC (4.10 dt ha-1) and RMSEP (4.61 dt ha-1) besides high prediction ability (validation R2 = 0.84). Correlations between measured and predicted data were found to be significantly very strong and complete with the highest correlation coefficient obtained for ANN model (r = 0.94, p wheat yield was mapped using ordinary kriging for both measured and predicted values to explore within-field and intra-treatment differences in crop productivity needed for assessing good calibration model. Results indicated similarities between the maps generated from the equations and the one generated from field measurements, which is in agreement with high portion of yield variability explained by spectral data (p wheat yield spatial prediction was assessed by comparing the cross

  9. Structure and orbital ordering of ultrathin LaVO{sub 3} probed by atomic resolution electron microscopy and Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lindfors-Vrejoiu, Ionela; Engelmayer, Johannes; Loosdrecht, Paul H.M. van [II. Physikalisches Institut, Koeln Univ. (Germany); Jin, Lei; Jia, Chun-Lin [Peter Gruenberg Institut (PGI-5) and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH (Germany); Himcinschi, Cameliu [Institut fuer Theoretische Physik, TU Bergakademie Freiberg (Germany); Hensling, Felix; Waser, Rainer; Dittmann, Regina [Peter Gruenberg Institut (PGI-7), Forschungszentrum Juelich GmbH (Germany)

    2017-03-15

    Orbital ordering has been less investigated in epitaxial thin films, due to the difficulty to evidence directly the occurrence of this phenomenon in thin film samples. Atomic resolution electron microscopy enabled us to observe the structural details of the ultrathin LaVO{sub 3} films. The transition to orbital ordering of epitaxial layers as thin as ∼4 nm was probed by temperature-dependent Raman scattering spectroscopy of multilayer samples. From the occurrence and temperature dependence of the 700 cm{sup -1} Raman active mode it can be inferred that the structural phase transition associated with orbital ordering takes place in ultrathin LaVO{sub 3} films at about 130 K. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Spanning or looping? The order and conformation of bipolar phospholipids in lipid membranes using 2H NMR spectroscopy.

    Science.gov (United States)

    Cuccia, L A; Morin, F; Beck, A; Hébert, N; Just, G; Lennox, R B

    2000-12-01

    Solid-state 2H NMR spectroscopy was used to study and characterize the conformation and order of bolaform lipid membranes. A series of 2H-labeled bolaform phosphatidylcholines has been synthesized and their properties compared to a [D4]dimyristoylphosphatidylcholine (DMPC) and a [D8]-32 macrocyclic phosphatidylcholine. 31P NMR measurements establish that the aqueous dispersions of these lipids adopt lamellar phases. Computational dePakeing was used to extract the spectrum of the oriented system from spectra consisting of a superposition of randomly oriented domains in an unoriented sample. A large (> 90 %) and constant value for the normalized segmental order parameter (Smol) was observed for all positions along the diacyl chain of the bolaform lipids and only a small population ( 90%) of the bolaform lipids is assigned to a highly ordered, spanning conformer.

  11. Ordered Gold Nanobowl Arrays as Substrates for Surface-Enhanced Raman Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    CHEN Ling; LIU Fan-Xin; ZHAN Peng; PAN Jian; WANG Zhen-Lin

    2011-01-01

    @@ We demonstrate that an interlinked gold half-shell array fabricated by metal deposition on a sacrificial twodimensional colloidal crystal template can show a large enhancement in surface-enhanced Raman spectroscopy at its main transmission resonance.It isfurther observed that Raman signal enhancement shows a noticeable difference when reversing the orientations of the Au nanobowls in relation to the underlying flat dielectric substrate.As the pump laser wavelength is tuned in the vicinity of the resonant plasmonic mode of the structure,the nhancement on an upward Au nanobowl array can be five-fold compared to that on a downward one.Numerical simulation confirms that for the upward nanobowls,a strong localized mode inside the Au nanobowls is formed at the resonant excitation wavelength,which helps to explain this observed extra enhancement in Raman scattering.%We demonstrate that an interlinked gold half-shell array fabricated by metal deposition on a sacrificial twodimensional colloidal crystal template can show a large enhancement in surface-enhanced Raman spectroscopy at its main transmission resonance.It is further observed that Raman signal enhancement shows a noticeable difference when reversing the orientations of the Au nanobowls in relation to the underlying flat dielectric substrate.As the pump laser wavelength is tuned in the vicinity of the resonant plasmonic mode of the structure, the enhancement on an upward Au nanobowl array can be five-fold compared to that on a downward one.Numerical simulation confirms that for the upward nanobowls, a strong localized mode inside the Au nanobowls is formed at the resonant excitation wavelength, which helps to explain this observed extra enhancement in Raman scattering.

  12. Insight into the electroreduction of nitrate ions at a copper electrode, in neutral solution, after determination of their diffusion coefficient by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Aouina, Nizar; Cachet, Hubert [Laboratoire Interfaces et Systemes Electrochimiques - UPR15 du CNRS, Universite Pierre et Marie Curie - Paris 6, 4, place Jussieu, F-75005 Paris (France); Debiemme-chouvy, Catherine, E-mail: catherine.debiemme-chouvy@upmc.f [Laboratoire Interfaces et Systemes Electrochimiques - UPR15 du CNRS, Universite Pierre et Marie Curie - Paris 6, 4, place Jussieu, F-75005 Paris (France); Tran, Thi Tuyet Mai [Laboratoire Interfaces et Systemes Electrochimiques - UPR15 du CNRS, Universite Pierre et Marie Curie - Paris 6, 4, place Jussieu, F-75005 Paris (France)

    2010-10-01

    The electrochemical reduction of nitrate ions at a copper electrode in an unbuffered neutral aqueous solution is studied. Using a two compartment electrochemical cell, three stationary cathodic waves, noted P1, P2 and P3, were evidenced by cyclic voltammetry at -0.9, -1.2 and -1.3 V/SCE, respectively. By comparing the electrochemical response of nitrate and nitrite containing solutions, P1 was attributed to the reduction of nitrate to nitrite. In order to assign P2 and P3 features by determining the number of electrons involved at the corresponding potential, rotating disk electrode experiments at various rotation speeds, combined with linear sweep voltammetry, were performed. Current data analysis at a given potential was carried out using Koutecky-Levich treatment taking into account water reduction. Confident values of the diffusion coefficient D of nitrate ions were assessed by electrochemical impedance spectroscopy for nitrate concentrations of 10{sup -3}, 10{sup -2} and 10{sup -1} M. For a nitrate concentration of 10{sup -2} M, D was found to be 1.31 x 10{sup -5} cm{sup 2} s{sup -1} allowing the number of electrons to be determined as 6 for P2 and 8 for P3, in accordance with nitrate reduction into hydroxylamine and ammonia, respectively. The formation of hydroxylamine was confirmed by the observation of its reoxidation at a Pt microelectrode present at the Cu electrode/nitrate solution interface.

  13. 1H magnetic resonance spectroscopy and diffusion weighted imaging findings of medulloblastoma in 3.0T MRI A retrospective analysis of 17 cases

    Institute of Scientific and Technical Information of China (English)

    Guangyao Wu; Haopeng Pang; Prasanna Ghimire; Guobing Liu

    2012-01-01

    1H magnetic resonance spectroscopy and diffusion weighted imaging features of the cerebellar vermis in 17 medulloblastoma patients were retrospectively analyzed, and 17 healthy volunteers were selected as controls. 1H magnetic resonance spectroscopy showed that in all 17 medulloblastoma patients, N-acetyl aspartate and creatine peaks were significantly decreased, the choline peak was significantly increased, and there was evidence of a myo-inositol peak. Further, 11 patients showed a low taurine peak at 3.4 ppm, five patients showed a lipid peak at 0.9–1.3 ppm, and three patients showed a negative lactic acid peak at 1.33 ppm. Compared with the control group, the ratios of N-acetyl aspartate/choline and N-acetyl aspartate/creatine were significantly decreased, and the ratio of choline/creatine was increased, in medulloblastoma patients. Diffusion weighted imaging displayed hyperintensity and decreased apparent diffusion coefficient in medulloblastoma patients. These findings indicate that 1H magnetic resonance spectroscopy and diffusion weighted imaging are useful for qualitative diagnosis of medulloblastoma.

  14. Comparison of cobinamide to hydroxocobalamin in reversing cyanide physiologic effects in rabbits using diffuse optical spectroscopy monitoring

    Science.gov (United States)

    Brenner, Matthew; Mahon, Sari B.; Lee, Jangwoen; Kim, Jae; Mukai, David; Goodman, Seth; Kreuter, Kelly A.; Ahdout, Rebecca; Mohammad, Othman; Sharma, Vijay S.; Blackledge, William; Boss, Gerry R.

    2010-01-01

    Our purpose is to compare cobinamide to hydroxocobalamin in reversing cyanide (CN)-induced physiologic effects in an animal model using diffuse optical spectroscopy (DOS). Cyanide poisoning is a major threat worldwide. Cobinamide is a novel molecule that can bind two molecules of cyanide, has a much higher binding affinity than hydroxocobalamin, and is more water soluble. We investigated the ability of equimolar doses of cobinamide and hydroxocobalamin to reverse the effects of cyanide exposure in an animal model monitored continuously by DOS. Cyanide toxicity was induced in 16 New Zealand white rabbits by intravenous infusion. Animals were divided into three groups: controls (n=5) received saline following cyanide, hydroxocobalamin (N=6) following cyanide, and cobinamide (N=5) following cyanide. Cobinamide caused significantly faster and more complete recovery of oxy- and deoxyhemoglobin concentrations in cyanide-exposed animals than hydroxocobalamin- or saline-treated animals, with a recovery time constant of 13.8+/-7.1 min compared to 75.4+/-25.1 and 76.4+/-42.7 min, for hydroxocobalamin- and saline-treated animals, respectively (p<0.0001). This study indicates that cobinamide more rapidly and completely reverses the physiologic effects of cyanide than equimolar doses of cobalamin at the dose used in this study, and CN effects and response can be followed noninvasively using DOS.

  15. Ultrafast wavelength multiplexed broad bandwidth digital diffuse optical spectroscopy for in vivo extraction of tissue optical properties

    Science.gov (United States)

    Torjesen, Alyssa; Istfan, Raeef; Roblyer, Darren

    2017-03-01

    Frequency-domain diffuse optical spectroscopy (FD-DOS) utilizes intensity-modulated light to characterize optical scattering and absorption in thick tissue. Previous FD-DOS systems have been limited by large device footprints, complex electronics, high costs, and limited acquisition speeds, all of which complicate access to patients in the clinical setting. We have developed a new digital DOS (dDOS) system, which is relatively compact and inexpensive, allowing for simplified clinical use, while providing unprecedented measurement speeds. The dDOS system utilizes hardware-integrated custom board-level direct digital synthesizers and an analog-to-digital converter to generate frequency sweeps and directly measure signals utilizing undersampling at six wavelengths modulated at discrete frequencies from 50 to 400 MHz. Wavelength multiplexing is utilized to achieve broadband frequency sweep measurements acquired at over 97 Hz. When compared to a gold-standard DOS system, the accuracy of optical properties recovered with the dDOS system was within 5.3% and 5.5% for absorption and reduced scattering coefficient extractions, respectively. When tested in vivo, the dDOS system was able to detect physiological changes throughout the cardiac cycle. The new FD-dDOS system is fast, inexpensive, and compact without compromising measurement quality.

  16. Microrheology: Structural evolution under static and dynamic conditions by simultaneous analysis of confocal microscopy and diffusing wave spectroscopy

    Science.gov (United States)

    Nicolas, Yves; Paques, Marcel; Knaebel, Alexandra; Steyer, Alain; Munch, Jean-Pierre; Blijdenstein, Theo B. J.; van Aken, George A.

    2003-08-01

    An oscillatory shear configuration was developed to improve understanding of structural evolution during deformation. It combines an inverted confocal scanning laser microscope (CSLM) and a special sample holder that can apply to the sample specific deformation: oscillatory shear or steady strain. In this configuration, a zero-velocity plane is created in the sample by moving two plates in opposite directions, thereby providing stable observation conditions of the structural behavior under deformation. The configuration also includes diffusion wave spectroscopy (DWS) to monitor the network properties via particle mobility under static and dynamic conditions. CSLM and DWS can be performed simultaneously and three-dimensional images can be obtained under static conditions. This configuration is mainly used to study mechanistic phenomena like particle interaction, aggregation, gelation and network disintegration, interactions at interfaces under static and dynamic conditions in semisolid food materials (desserts, dressings, sauces, dairy products) and in nonfood materials (mineral emulsions, etc.). Preliminary data obtained with this new oscillatory shear configuration are described that demonstrate their capabilities and the potential contribution to other areas of application also.

  17. Comparison of cobinamide to hydroxocobalamin in reversing cyanide physiologic effects in rabbits using diffuse optical spectroscopy monitoring

    Science.gov (United States)

    Brenner, Matthew; Mahon, Sari B.; Lee, Jangwoen; Kim, Jae; Mukai, David; Goodman, Seth; Kreuter, Kelly A.; Ahdout, Rebecca; Mohammad, Othman; Sharma, Vijay S.; Blackledge, William; Boss, Gerry R.

    2010-01-01

    Our purpose is to compare cobinamide to hydroxocobalamin in reversing cyanide (CN)–induced physiologic effects in an animal model using diffuse optical spectroscopy (DOS). Cyanide poisoning is a major threat worldwide. Cobinamide is a novel molecule that can bind two molecules of cyanide, has a much higher binding affinity than hydroxocobalamin, and is more water soluble. We investigated the ability of equimolar doses of cobinamide and hydroxocobalamin to reverse the effects of cyanide exposure in an animal model monitored continuously by DOS. Cyanide toxicity was induced in 16 New Zealand white rabbits by intravenous infusion. Animals were divided into three groups: controls (n=5) received saline following cyanide, hydroxocobalamin (N=6) following cyanide, and cobinamide (N=5) following cyanide. Cobinamide caused significantly faster and more complete recovery of oxy- and deoxyhemoglobin concentrations in cyanide-exposed animals than hydroxocobalamin- or saline-treated animals, with a recovery time constant of 13.8±7.1 min compared to 75.4±25.1 and 76.4±42.7 min, for hydroxocobalamin- and saline-treated animals, respectively (pcyanide than equimolar doses of cobalamin at the dose used in this study, and CN effects and response can be followed noninvasively using DOS. PMID:20210475

  18. Space-resolved diffusing wave spectroscopy measurements of the macroscopic deformation and the microscopic dynamics in tensile strain tests

    Science.gov (United States)

    Nagazi, Med-Yassine; Brambilla, Giovanni; Meunier, Gérard; Marguerès, Philippe; Périé, Jean-Noël; Cipelletti, Luca

    2017-01-01

    We couple a laser-based, space-resolved dynamic light scattering apparatus to a universal traction machine for mechanical extensional tests. We perform simultaneous optical and mechanical measurements on polyether ether ketone, a semi-crystalline polymer widely used in the industry. Due to the high turbidity of the sample, light is multiply scattered by the sample and the diffusing wave spectroscopy (DWS) formalism is used to interpret the data. Space-resolved DWS yields spatial maps of the sample strain and of the microscopic dynamics. An excellent agreement is found between the strain maps thus obtained and those measured by a conventional stereo-digital image correlation technique. The microscopic dynamics reveals both affine motion and plastic rearrangements. Thanks to the extreme sensitivity of DWS to displacements as small as 1 nm, plastic activity and its spatial localization can be detected at an early stage of the sample strain, making the technique presented here a valuable complement to existing material characterization methods.

  19. Ecological risk assessment on heavy metals in soils: Use of soil diffuse reflectance mid-infrared Fourier-transform spectroscopy

    Science.gov (United States)

    Wang, Cheng; Li, Wei; Guo, Mingxing; Ji, Junfeng

    2017-02-01

    The bioavailability of heavy metals in soil is controlled by their concentrations and soil properties. Diffuse reflectance mid-infrared Fourier-transform spectroscopy (DRIFTS) is capable of detecting specific organic and inorganic bonds in metal complexes and minerals and therefore, has been employed to predict soil composition and heavy metal contents. The present study explored the potential of DRIFTS for estimating soil heavy metal bioavailability. Soil and corresponding wheat grain samples from the Yangtze River Delta region were analyzed by DRIFTS and chemical methods. Statistical regression analyses were conducted to correlate the soil spectral information to the concentrations of Cd, Cr, Cu, Zn, Pb, Ni, Hg and Fe in wheat grains. The principal components in the spectra influencing soil heavy metal bioavailability were identified and used in prediction model construction. The established soil DRIFTS-based prediction models were applied to estimate the heavy metal concentrations in wheat grains in the mid-Yangtze River Delta area. The predicted heavy metal concentrations of wheat grain were highly consistent with the measured levels by chemical analysis, showing a significant correlation (r2 > 0.72) with acceptable root mean square error RMSE. In conclusion, DRIFTS is a promising technique for assessing the bioavailability of soil heavy metals and related ecological risk.

  20. Diffuse correlation spectroscopy (DCS) study of blood flow changes during low level laser therapy (LLLT): a preliminary report

    Science.gov (United States)

    Soni, Sagar; Wang, Xinlong; Liu, Hanli; Tian, Fenghua

    2017-02-01

    Photobiomodulation with low-power, high-fluence light in the near-infrared range (600-1100nm), also known as low level laser therapy (LLLT), has been used for promoting healing of wounds, reducing pain, and so on. Understanding its physiological effect is essential for treatment optimization and evaluation. In this study, we used diffuse correlation spectroscopy (DCS) to investigate the changes of regional blood flow in skeletal muscle induced by a single session of LLLT. DCS is an emerging optical modality to probe microvascular blood flow in human tissues in vivo. We have developed a software-based autocorrelator system with the benefits such as flexibility in raw photon count data processing, portability and low cost. LLLT was administered at the human forearm with a 1064-nm, continuous-wave laser. The emitting power was 3.4 W in an area of 13.6 cm2, corresponding to 0.25W/cm2 irradiance. The emitting duration was 10 minutes. Eight healthy adults of any ethnic background, in an age range of 18-40 years old were included. The results indicate that LLLT causes reliable changes in regional blood flow. However, it remains unclear whether these changes are physiological or attributed to the heating effect of the stimulation laser.

  1. A simple and green analytical method for determination of glyphosate in commercial formulations and water by diffuse reflectance spectroscopy

    Science.gov (United States)

    da Silva, Aline Santana; Fernandes, Flávio Cesar Bedatty; Tognolli, João Olímpio; Pezza, Leonardo; Pezza, Helena Redigolo

    2011-09-01

    This article describes a simple, inexpensive, and environmentally friendly method for the monitoring of glyphosate using diffuse reflectance spectroscopy. The proposed method is based on reflectance measurements of the colored compound produced from the spot test reaction between glyphosate and p-dimethylaminocinnamaldehyde ( p-DAC) in acid medium, using a filter paper as solid support. Experimental designs were used to optimize the analytical conditions. All reflectance measurements were carried out at 495 nm. Under optimal conditions, the glyphosate calibration graphs obtained by plotting the optical density of the reflectance signal (A R) against the concentration were linear in the range 50-500 μg mL -1, with a correlation coefficient of 0.9987. The limit of detection (LOD) for glyphosate was 7.28 μg mL -1. The technique was successfully applied to the direct determination of glyphosate in commercial formulations, as well as in water samples (river water, pure water and mineral drinking water) after a previous clean-up or pre-concentration step. Recoveries were in the ranges 93.2-102.6% and 91.3-102.9% for the commercial formulations and water samples, respectively.

  2. Continuous monitoring of absolute cerebral blood flow by combining diffuse correlation spectroscopy and time-resolved near-infrared technology

    Science.gov (United States)

    Diop, Mamadou; Lee, Ting-Yim; St. Lawrence, Keith

    2011-02-01

    Continuous bedside monitoring of cerebral blood flow (CBF) in patients recovering from brain injury could improve the detection of impaired substrate delivery, which can exacerbate injury and worsen outcome. Diffuse correlation spectroscopy (DCS) provides the ability to monitor perfusion changes continuously, but it is difficult to quantify absolute blood flow - leading to uncertainties as to whether or not CBF has fallen to ischemic levels. To continuously measure CBF, we propose to calibrate DCS data using a single time-point, time-resolved near-infrared (TR-NIR) technique for measuring absolute CBF. Experiments were conducted on newborn piglets in which CBF was increased by raising the arterial tension of CO2 (40-62 mmHg) and decreased by carotid occlusion. For validation, values of CBF measured by TR-NIR were converted into blood flow changes and compared to CBF changes measured by DCS. A strong correlation between perfusion changes from the two techniques was revealed (slope = 0.98 and R2 = 0.96), suggesting that a single time-point CBF measurement by TR-NIR can be used to convert continuous DCS data into units of CBF (ml/100g/min).

  3. Synergistic efficacy of salicylic acid with a penetration enhancer on human skin monitored by OCT and diffuse reflectance spectroscopy

    Science.gov (United States)

    Zhao, Qingliang; Dai, Cuixia; Fan, Shanhui; Lv, Jing; Nie, Liming

    2016-10-01

    Salicylic acid (SA) has been frequently used as a facial chemical peeling agent (FCPA) in various cosmetics for facial rejuvenation and dermatological treatments in the clinic. However, there is a tradeoff between therapeutic effectiveness and possible adverse effects caused by this agent for cosmetologists. To optimize the cosmetic efficacy with minimal concentration, we proposed a chemical permeation enhancer (CPE) azone to synergistically work with SA on human skin in vivo. The optical properties of human skin after being treated with SA alone and SA combined with azone (SA@azone) were successively investigated by diffuse reflectance spectroscopy (DRS) and optical coherence tomography (OCT). Our results revealed that as the SA concentration increased, the light reflectance decreased and the absorption increased. We also found that SA@azone exhibited a synergistic effect on enhancing light penetration and OCT imaging depth. We demonstrated that the combination of DRS and OCT techniques could be used as a noninvasive, rapid and accurate measurement method to monitor the subtle changes of skin tissue after treatment with FCPA and CPE. The approach will greatly benefit the development of clinical cosmetic surgery, dermatosis diagnosis and therapeutic effect inspection in related biomedical studies.

  4. Ecological risk assessment on heavy metals in soils: Use of soil diffuse reflectance mid-infrared Fourier-transform spectroscopy

    Science.gov (United States)

    Wang, Cheng; Li, Wei; Guo, Mingxing; Ji, Junfeng

    2017-01-01

    The bioavailability of heavy metals in soil is controlled by their concentrations and soil properties. Diffuse reflectance mid-infrared Fourier-transform spectroscopy (DRIFTS) is capable of detecting specific organic and inorganic bonds in metal complexes and minerals and therefore, has been employed to predict soil composition and heavy metal contents. The present study explored the potential of DRIFTS for estimating soil heavy metal bioavailability. Soil and corresponding wheat grain samples from the Yangtze River Delta region were analyzed by DRIFTS and chemical methods. Statistical regression analyses were conducted to correlate the soil spectral information to the concentrations of Cd, Cr, Cu, Zn, Pb, Ni, Hg and Fe in wheat grains. The principal components in the spectra influencing soil heavy metal bioavailability were identified and used in prediction model construction. The established soil DRIFTS-based prediction models were applied to estimate the heavy metal concentrations in wheat grains in the mid-Yangtze River Delta area. The predicted heavy metal concentrations of wheat grain were highly consistent with the measured levels by chemical analysis, showing a significant correlation (r2 > 0.72) with acceptable root mean square error RMSE. In conclusion, DRIFTS is a promising technique for assessing the bioavailability of soil heavy metals and related ecological risk. PMID:28198802

  5. Synergistic efficacy of salicylic acid with a penetration enhancer on human skin monitored by OCT and diffuse reflectance spectroscopy

    Science.gov (United States)

    Zhao, Qingliang; Dai, Cuixia; Fan, Shanhui; Lv, Jing; Nie, Liming

    2016-01-01

    Salicylic acid (SA) has been frequently used as a facial chemical peeling agent (FCPA) in various cosmetics for facial rejuvenation and dermatological treatments in the clinic. However, there is a tradeoff between therapeutic effectiveness and possible adverse effects caused by this agent for cosmetologists. To optimize the cosmetic efficacy with minimal concentration, we proposed a chemical permeation enhancer (CPE) azone to synergistically work with SA on human skin in vivo. The optical properties of human skin after being treated with SA alone and SA combined with azone (SA@azone) were successively investigated by diffuse reflectance spectroscopy (DRS) and optical coherence tomography (OCT). Our results revealed that as the SA concentration increased, the light reflectance decreased and the absorption increased. We also found that SA@azone exhibited a synergistic effect on enhancing light penetration and OCT imaging depth. We demonstrated that the combination of DRS and OCT techniques could be used as a noninvasive, rapid and accurate measurement method to monitor the subtle changes of skin tissue after treatment with FCPA and CPE. The approach will greatly benefit the development of clinical cosmetic surgery, dermatosis diagnosis and therapeutic effect inspection in related biomedical studies. PMID:27721398

  6. High-order harmonic spectroscopy for molecular imaging of polyatomic molecules

    CERN Document Server

    Negro, M; Faccialà, D; De Silvestri, S; Vozzi, C; Stagira, S

    2014-01-01

    High-order harmonic generation is a powerful and sensitive tool for probing atomic and molecular structures, combining in the same measurement an unprecedented attosecond temporal resolution with a high spatial resolution, of the order of the angstrom. Imaging of the outermost molecular orbital by high-order harmonic generation has been limited for a long time to very simple molecules, like nitrogen. Recently we demonstrated a technique that overcame several of the issues that have prevented the extension of molecular orbital tomography to more complex species, showing that molecular imaging can be applied to a triatomic molecule like carbon dioxide. Here we report on the application of such technique to nitrous oxide (N2O) and acetylene (C2H2). This result represents a first step towards the imaging of fragile compounds, a category which includes most of the fundamental biological molecules.

  7. HQET at order 1/m. Pt. 2. Spectroscopy in the quenched approximation

    Energy Technology Data Exchange (ETDEWEB)

    Blossier, Benoit [CNRS et Paris-Sud XI Univ., Orsay (France). Lab. de Physique Theorique; Della Morte, Michele [Mainz Univ. (Germany). Inst. fuer Kernphysik; Garron, Nicolas [Universidad Autonoma de Madrid (Spain). Dept. de Fisica Teorica e Inst. de Fisica Teorica IFT-UAM/CSIC; Edinburgh Univ. (United Kingdom). SUPA, School of Physics; Hippel, Georg von [Mainz Univ. (Germany). Inst. fuer Kernphysik; DESY, Zeuthen (Germany). NIC; Mendes, Tereza [DESY, Zeuthen (Germany). NIC; Sao Paulo Univ., Sao Carlos (Brazil). IFSC; Simma, Hubert; Sommer, Rainer [DESY, Zeuthen (Germany). NIC

    2010-06-15

    Using Heavy Quark Effective Theory with non-perturbatively determined parameters in a quenched lattice calculation, we evaluate the splittings between the ground state and the first two radially excited states of the B{sub s} system at static order. We also determine the splitting between first excited and ground state, and between the B{sub s}{sup *} and B{sub s} ground states to order 1/m{sub b}. The Generalized Eigenvalue Problem and the use of all-to-all propagators are important ingredients of our approach. (orig.)

  8. Lithium ion micrometer diffusion in a garnet-type cubic Li7La3Zr2O12 (LLZO) studied using 7Li NMR spectroscopy

    Science.gov (United States)

    Hayamizu, Kikuko; Seki, Shiro; Haishi, Tomoyuki

    2017-01-01

    Mobile lithium ions in a cubic garnet Li7La3Zr2O12 (Al-stabilized) were studied using 7Li NMR spectroscopy for membrane and powder samples, the latter of which was ground from the membrane. Lithium diffusion in a micrometer space was measured using the pulsed-gradient spin-echo 7Li NMR method between 70 and 130 °C. When the observation time (Δ ) was shorter than 20 ms, the echo attenuation showed diffusive diffraction patterns, indicating that the Li+ diffusing space is not free but restricted. For longer Δ, the values of apparent diffusion constant (Dapparent) became gradually smaller to approach an equilibrated value (close to a tracer diffusion constant). In addition, the Dapparent depends on the pulse field gradient strength (g) and became smaller as g became larger. These experimental results suggest that the lithium ions diffuse through Li+ pathways surrounded by stationary anions and lithium ions, and are affected by collisions and diffractions. One-dimensional profiles of the membrane sample of thickness 0.5 mm were observed from 65 to 110 °C and the area intensity, as well as the lithium occurrence near the surface, increased with the increase in temperature. The temperature-dependent area intensity showed a correspondence to the number of Li+ carrier ions estimated from the ionic conductivity and the equilibrated diffusion constant through the Nernst-Einstein relationship.

  9. Lithium ion micrometer diffusion in a garnet-type cubic Li7La3Zr2O12 (LLZO) studied using (7)Li NMR spectroscopy.

    Science.gov (United States)

    Hayamizu, Kikuko; Seki, Shiro; Haishi, Tomoyuki

    2017-01-14

    Mobile lithium ions in a cubic garnet Li7La3Zr2O12 (Al-stabilized) were studied using (7)Li NMR spectroscopy for membrane and powder samples, the latter of which was ground from the membrane. Lithium diffusion in a micrometer space was measured using the pulsed-gradient spin-echo (7)Li NMR method between 70 and 130 °C. When the observation time (Δ) was shorter than 20 ms, the echo attenuation showed diffusive diffraction patterns, indicating that the Li(+) diffusing space is not free but restricted. For longer Δ, the values of apparent diffusion constant (Dapparent) became gradually smaller to approach an equilibrated value (close to a tracer diffusion constant). In addition, the Dapparent depends on the pulse field gradient strength (g) and became smaller as g became larger. These experimental results suggest that the lithium ions diffuse through Li(+) pathways surrounded by stationary anions and lithium ions, and are affected by collisions and diffractions. One-dimensional profiles of the membrane sample of thickness 0.5 mm were observed from 65 to 110 °C and the area intensity, as well as the lithium occurrence near the surface, increased with the increase in temperature. The temperature-dependent area intensity showed a correspondence to the number of Li(+) carrier ions estimated from the ionic conductivity and the equilibrated diffusion constant through the Nernst-Einstein relationship.

  10. Diffusion and molecular interactions in a methanol/polyimide system probed by coupling time-resolved FTIR spectroscopy with gravimetric measurements.

    Science.gov (United States)

    Musto, Pellegrino; Galizia, Michele; La Manna, Pietro; Pannico, Marianna; Mensitieri, Giuseppe

    2014-01-01

    In this contribution the diffusion of methanol in a commercial polyimide (PMDA-ODA) is studied by coupling gravimetric measurements with in-situ, time-resolved FTIR spectroscopy. The spectroscopic data have been treated with two complementary techniques, i.e., difference spectroscopy (DS) and least-squares curve fitting (LSCF). These approaches provided information about the overall diffusivity, the nature of the molecular interactions among the system components and the dynamics of the various molecular species. Additional spectroscopic measurements on thin film samples (about 2 μm) allowed us to identify the interaction site on the polymer backbone and to propose likely structures for the H-bonding aggregates. Molar absorptivity values from a previous literature report allowed us to estimate the population of first-shell and second-shell layers of methanol in the polymer matrix. In terms of diffusion kinetics, the gravimetric and spectroscopic estimates of the diffusion coefficients were found to be in good agreement with each other and with previous literature reports. A Fickian behavior was observed throughout, with diffusivity values markedly affected by the total concentration of sorbed methanol.

  11. Magnetic structures of vanadium iodide (VI2): long- and short-range order and Moessbauer spectroscopy.

    NARCIS (Netherlands)

    Kuindersma, S. R.; Sanchez, J. P.; Haas, C.

    1980-01-01

    Neutron diffraction data of VI2 show a magnetic phase transition at 14 K from a 120° magnetic structure to a collinear structure. The collinear structure is compatible with low-temp. Moessbauer spectra. The 120° structure is not a magnetic phase with long-range order but rather a paramagnetic phase

  12. Spectroscopy and decay constants from nonperturbative HQET at order 1/m

    Energy Technology Data Exchange (ETDEWEB)

    Blossier, Benoit [Paris 11 Univ., 91 - Orsay (France). Lab. de Physique Theorique; Della Morte, Michele [Mainz Univ. (Germany). Inst. fuer Kernphysik; Garron, Nicolas [Universidad Autonoma de Madrid (Spain). Dept. de Fisica Teorica y Inst. de Fisica Teorica UAM/CSIC; Hippel, Georg von; Mendes, Tereza; Simma, Hubert; Sommer, Rainer [NIC, DESY, Zeuthen (Germany)

    2009-11-15

    We carry out a thorough analysis with the GEVP method to obtain ground-state and first-excited-state masses and decay constants of bottom-strange (pseudo-scalar and vector) mesons. This computation is done for quenched, nonperturbatively renormalized HQET, including order 1/m{sub b} terms. The continuum limit is obtained using three lattice spacings and two static actions. (orig.)

  13. Stability and Convergence Analysis of Second-Order Schemes for a Diffuse Interface Model with Peng-Robinson Equation of State

    KAUST Repository

    Peng, Qiujin

    2017-09-18

    In this paper, we present two second-order numerical schemes to solve the fourth order parabolic equation derived from a diffuse interface model with Peng-Robinson Equation of state (EOS) for pure substance. The mass conservation, energy decay property, unique solvability and L-infinity convergence of these two schemes are proved. Numerical results demonstrate the good approximation of the fourth order equation and confirm reliability of these two schemes.

  14. Electronic and geometric properties of Au nanoparticles on Highly Ordered Pyrolytic Graphite (HOPG) studied using X-ray Photoelectron Spectroscopy (XPS) and Scanning Tunneling Microscopy (STM).

    Science.gov (United States)

    Lopez-Salido, Ignacio; Lim, Dong Chan; Dietsche, Rainer; Bertram, Nils; Kim, Young Dok

    2006-01-26

    Au nanoparticles grown on mildly sputtered Highly Ordered Pyrolytic Graphite (HOPG) surfaces were studied using Scanning Tunneling Microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS). The results were compared with those of Ag nanoparticles on the same substrate. By varying the defect densities of HOPG and the Au coverages, one can create Au nanoparticles in various sizes. At high Au coverages, the structures of the Au films significantly deviate from the ideal truncated octahedral form: the existence of many steps between different Au atomic layers can be observed, most likely due to a high activation barrier of the diffusion of Au atoms across the step edges. This implies that the particle growth at room temperature is strongly limited by kinetic factors. Hexagonal shapes of Au structures could be identified, indicating preferential growth of Au nanostructures along the (111) direction normal to the surface. In the case of Au, XPS studies reveal a weaker core level shift with decreasing particle size compared to the 3d level in similarly sized Ag particles. Also taking into account the Auger analysis of the Ag particles, the core level shifts of the metal nanoparticles on HOPG can be understood in terms of the metal/substrate charge transfer. Ag is (partially) positively charged, whereas Au negatively charged on HOPG. It is demonstrated that XPS can be a useful tool to study metal-support interactions, which plays an important role for heterogeneous catalysis, for example.

  15. Coupled third-order simplified spherical harmonics and diffusion equation-based fluorescence tomographic imaging of liver cancer

    Science.gov (United States)

    Chen, Xueli; Sun, Fangfang; Yang, Defu; Liang, Jimin

    2015-09-01

    For fluorescence tomographic imaging of small animals, the liver is usually regarded as a low-scattering tissue and is surrounded by adipose, kidneys, and heart, all of which have a high scattering property. This leads to a breakdown of the diffusion equation (DE)-based reconstruction method as well as a heavy computational burden for the simplified spherical harmonics equation (SPN). Coupling the SPN and DE provides a perfect balance between the imaging accuracy and computational burden. The coupled third-order SPN and DE (CSDE)-based reconstruction method is developed for fluorescence tomographic imaging. This is achieved by doubly using the CSDE for the excitation and emission processes of the fluorescence propagation. At the same time, the finite-element method and hybrid multilevel regularization strategy are incorporated in inverse reconstruction. The CSDE-based reconstruction method is first demonstrated with a digital mouse-based liver cancer simulation, which reveals superior performance compared with the SPN and DE-based methods. It is more accurate than the DE-based method and has lesser computational burden than the SPN-based method. The feasibility of the proposed approach in applications of in vivo studies is also illustrated with a liver cancer mouse-based in situ experiment, revealing its potential application in whole-body imaging of small animals.

  16. TRAVELLING FRONT SOLUTION FOR A CLASS OF COMPETITION-DIFFUSION SYSTEM WITH HIGH-ORDER SINGULAR POINT

    Institute of Scientific and Technical Information of China (English)

    WangShu; XieChunhong

    1999-01-01

    In this paper,the existence of travelling front solution for a class of competition-diffusion system with hlgh-order singular point w=d1wixx-waiifi(w),x∈R,t>0,i=1,2 (I)is studied,where d1 ai>0 (i=1,2) and ω=(w1(x,t)t),w2(x,t).Under the certain assumptions on f, it is showed that if a1<1 for some i,then (I) has no travelling front solution,if ai≥1 for i=1,2,then there is a c0,c1:c0≥cn >0,where cn is called the minimal wave speed of ( I ) ,such that if c≥c0 or c=n ,then (I)has a travelling front solution,if c<cn ,then (I)has no travelling front solution hy using the shooting method in combination with a compactness argument.

  17. Use of polyurethane foam and 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline for determination of nitrite by diffuse reflectance spectroscopy and colorimetry.

    Science.gov (United States)

    Apyari, V V; Dmitrienko, S G; Ostrovskaya, V M; Anaev, E K; Zolotov, Y A

    2008-07-01

    Polyurethane foam (PUF) has been suggested as a solid polymeric reagent for determination of nitrite. The determination is based on the diazotization of end toluidine groups of PUF with nitrite in acidic medium followed by coupling of polymeric diazonium cation with 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline. The intensely colored polymeric azodye formed in this reaction can be used as a convenient analytic form for the determination of nitrite by diffuse reflectance spectroscopy (c (min) = 0.7 ng mL(-1)). The possibility of using a desktop scanner, digital camera, and computer data processing for the numerical evaluation of the color intensity of the polymeric azodye has been investigated. A scanner and digital camera can be used for determination of nitrite with the same sensitivity and reproducibility as with diffuse reflectance spectroscopy. The approach developed was applied for determination of nitrite in river water and human exhaled breath condensate.

  18. Assessing Guest-Molecule Diffusion in Heterogeneous Powder Samples of Metal-Organic Frameworks through Pulsed-Field-Gradient (PFG) NMR Spectroscopy.

    Science.gov (United States)

    Thoma, Roland; Kärger, Jörg; de Sousa Amadeu, Nader; Nießing, Sandra; Janiak, Christoph

    2017-07-19

    Investigation of guest diffusion in porous metal-organic frameworks (MOFs) is of major importance, because many porosity-related properties of MOFs are influenced by diffusion effects. The diffusion of dimethyl sulfoxide (DMSO) in the MOF MIL-53-NH2 (Al) was investigated through pulsed-field-gradient (PFG) NMR spectroscopy. The microporous material was synthesized in small crystallites (under 500 nm), which agglomerated in a large range of particle sizes (from hundreds of nanometers to tens of micrometers), giving a morphologically very heterogeneous sample. No special agglomeration pattern could be observed, which makes a PFG NMR investigation very challenging, yet it represents a realistic situation for the diffusion of guest molecules in porous materials. We were able to distinguish between two diffusion regimes existing in parallel with each other over the total range from 15 to 200 ms of observation times as accessible in the experiments: In the large crystal agglomerates (diameters above 20 μm), guest movement was found to be subdiffusive, with a time exponent κ =0.8 (rather than one as for normal diffusion). Guest diffusion in the remaining, smaller host particles followed the pattern of normal diffusion within a bed of spheres of impenetrable external surfaces, with a size distribution in good agreement with that of the material under study. Diffusion in a rather complex system could thus be referred to a two-region model with new potentials for application to systems of intricate topology. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Minimal hepatic encephalopathy in children with liver cirrhosis: diffusion-weighted MR imaging and proton MR spectroscopy of the brain

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Razek, Ahmed Abdel Khalek; Ezzat, Amany [Mansoura University Hospital, Department of Diagnostic Radiology, Mansoura Faculty of Medicine, Mansoura (Egypt); Abdalla, Ahmed; Megahed, Ahmed; Barakat, Tarek [Mansoura Children Hospital, Gastroenterology and Hepatology Unit, Mansoura Faculty of Medicine, Mansoura (Egypt)

    2014-10-15

    The aim of this work was to detect minimal hepatic encephalopathy (minHE) in children with diffusion-weighted MR imaging (DWI) and proton magnetic resonance spectroscopy ({sup 1}H-MRS) of the brain. Prospective study conducted upon 30 consecutive children (age range 6-16 years, 21 boys and 9 girls) with liver cirrhosis and 15 age- and sex-matched healthy control children. Patients with minHE (n = 17) and with no minHE (n = 13) groups and control group underwent DWI, {sup 1}H-MRS, and neuropsychological tests (NPTs). The glutamate or glutamine (Glx), myoinositol (mI), choline (Cho), and creatine (Cr) at the right ganglionic region were determined at {sup 1}H-MRS. The apparent diffusion coefficient (ADC) value and metabolic ratios of Glx/Cr, mI/Cr, and Cho/Cr were calculated. There was elevated ADC value and Glx/Cr and decreased mI/CI and Ch/Cr in patients with minHE compared to no minHE and control group. There was significant difference between minHE, no minHE, and control group in the ADC value (P = 0.001 for all groups), GLx/Cr (P = 0.001 for all groups), mI/Cr (P = 0.004, 0.001, and 0.001, respectively), Ch/Cr (P = 0.001 for all groups), and full-scale IQ of NPT (P = 0.001, 0.001, and 0.143, respectively). The NPT of minHE had negative correlation with ADC value (r = -0.872, P = 0.001) and GLx/Cr (r = -0.812, P = 0.001) and positive correlation with mI/Cr (r = 0.732, P = 0.001). DWI and {sup 1}H-MRS are imaging modalities that can detect minHE in children with liver cirrhosis and correlate well with parameters of NPT. (orig.)

  20. In the assessment of supratentorial glioma grade: The combined role of multivoxel proton MR spectroscopy and diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Q.-G. [Department of Neuroradiology, Union hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Xu, H.-B., E-mail: xuhaibo1120@hotmail.com [Department of Neuroradiology, Union hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Liu, F.; Guo, W. [Department of Neuroradiology, Union hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Kong, X.-C. [Department of Imaging technology, Union hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China); Wu, Y. [Department of Maternal and Child Health Care, Public Health School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China)

    2011-10-15

    Aim: To detect a difference in the parameters derived from proton magnetic resonance spectroscopy ({sup 1}H-MRS) and diffusion tensor imaging (DTI) between low-grade and high-grade gliomas, and to evaluate whether the combination of these two techniques can improve the diagnostic accuracy of conventional magnetic resonance imaging (MRI) in supratentorial glioma grading. Materials and methods: Thirty patients with histologically proved supratentorial brain gliomas (12 low grade, 18 high grade) were prospectively evaluated with contrast material-enhanced MRI, DTI, and multivoxel {sup 1}H-MRS (135 ms echo time). The tumour grades determined using the three methods were then compared with those obtained at histopathology. Receiver operating characteristic (ROC) analyses were performed to determine the optimum thresholds for glioma grading. Independent sample t-test, Spearman's rank correlation, and the Fisher's exact test were also carried out for statistical analysis. p < 0.05 was considered statistically significant. Results: Statistically significant differences were found between the low-grade and high-grade gliomas for the choline (Cho)/creatine (Cr), N-acetylaspartate (NAA)/Cr, NAA/Cho ratio in the tumours (p < 0.01), apparent diffusion coefficient (ADC) value (p < 0.01), and fractional anisotropy (FA) value (p < 0.05) in the tumours. The NAA/Cr and NAA/Cho ratios and the calculated ADC value significantly correlated with the histological grading of the gliomas (p < 0.01). Using a threshold value of 0.66 for tumour NAA/Cr, 0.265 for NAA/Cho, 1118.1 x 10{sup -6} mm{sup 2}/s for the calculated ADC value, corresponding to the maximum Youden index from the ROC curve of the above-selected parameters, the resultant sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs), and Kappa values were all higher and the fraction of misclassified tumour was lower when compared with conventional MRI. However, only NAA/Cho and

  1. Assessment of bone marrow changes in postmenopausal women with varying bone densities: magnetic resonance spectroscopy and diffusion magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    LIU Yong; TANG Guang-yu; TANG Rong-biao; PENG Yi-feng; LI Wei

    2010-01-01

    Background Recent studies suggest that bone marrow adipose tissue might play a role in the pathogenesis of osteoporosis. There are inconsistent findings on the relationship among marrow fat content, bone mineral density and apparent diffusion coefficient (ADC). This study aimed to prospectively explore the efficacy of MR spectroscopy (MRS)and diffusion-weighted MR imaging (DWI) in detecting vertebral marrow changes in postmenopausal women with varying bone densities.Methods Both MRS and DWI of the lumber spine were performed in 102 postmenopausal women (mean age,(67.3±6.5) years; range, 55-83 years), who underwent dual X-ray absorptiometry. Marrow fat content and ADC were compared and correlated among three groups: 24 with normal bone density, 31 with osteopenia and 47 with osteoporosis.Results Vertebral marrow fat content was significantly increased in the osteoporotic group ((65.60±7.68)%, P <0.001)and the osteopenic group ((57.68±6.45)%, P <0.001), when compared with the normal bone density group ((51.67±3.27)%). ADC values were significantly decreased in the osteoporotic group ((0.39±0.03)×10-3mm2/s, P <0.001)and in the osteopenic group ((0.42±0.02)×10-3mm2/s, P <0.001), when compared with the normal bone density group ((0.47±0.03)×10-3 mm2/s). The marrow fat content negatively correlated with both bone density (r=-0.731, P <0.001)and marrow ADC (r=-0.572, P <0.001). The bone density positively correlated with the ADC values (r=0.802, P<0.001).Conclusions Postmenopausal women experience a corresponding increase in vertebral marrow fat content as the bone density decreases. Marrow fat content and ADC correlate to the bone density. MRS and DWI may indirectly assess the early bone marrow changes in postmenopausal women.

  2. Organization-wide adoption of computerized provider order entry systems: a study based on diffusion of innovations theory

    Directory of Open Access Journals (Sweden)

    Timpka Toomas

    2009-12-01

    Full Text Available Abstract Background Computerized provider order entry (CPOE systems have been introduced to reduce medication errors, increase safety, improve work-flow efficiency, and increase medical service quality at the moment of prescription. Making the impact of CPOE systems more observable may facilitate their adoption by users. We set out to examine factors associated with the adoption of a CPOE system for inter-organizational and intra-organizational care. Methods The diffusion of innovation theory was used to understand physicians' and nurses' attitudes and thoughts about implementation and use of the CPOE system. Two online survey questionnaires were distributed to all physicians and nurses using a CPOE system in county-wide healthcare organizations. The number of complete questionnaires analyzed was 134 from 200 nurses (67.0% and 176 from 741 physicians (23.8%. Data were analyzed using descriptive-analytical statistical methods. Results More nurses (56.7% than physicians (31.3% stated that the CPOE system introduction had worked well in their clinical setting (P P = P = 0.041. We found that in particular the received relative advantages of the CPOE system were estimated to be significantly (P P Conclusions Qualifications for CPOE adoption as defined by three attributes of diffusion of innovation theory were not satisfied in the study setting. CPOE systems are introduced as a response to the present limitations in paper-based systems. In consequence, user expectations are often high on their relative advantages as well as on a low level of complexity. Building CPOE systems therefore requires designs that can provide rather important additional advantages, e.g. by preventing prescription errors and ultimately improving patient safety and safety of clinical work. The decision-making process leading to the implementation and use of CPOE systems in healthcare therefore has to be improved. As any change in health service settings usually faces resistance

  3. Effect of modulation frequency bandwidth on measurement accuracy and precision for digital diffuse optical spectroscopy (dDOS)

    Science.gov (United States)

    Jung, Justin; Istfan, Raeef; Roblyer, Darren

    2014-03-01

    Near-infrared (NIR) frequency-domain Diffuse Optical Spectroscopy (DOS) is an emerging technology with a growing number of potential clinical applications. In an effort to reduce DOS system complexity and improve portability, we recently demonstrated a direct digital sampling method that utilizes digital signal generation and detection as a replacement for more traditional analog methods. In our technique, a fast analog-to-digital converter (ADC) samples the detected time-domain radio frequency (RF) waveforms at each modulation frequency in a broad-bandwidth sweep (50- 300MHz). While we have shown this method provides comparable results to other DOS technologies, the process is data intensive as digital samples must be stored and processed for each modulation frequency and wavelength. We explore here the effect of reducing the modulation frequency bandwidth on the accuracy and precision of extracted optical properties. To accomplish this, the performance of the digital DOS (dDOS) system was compared to a gold standard network analyzer based DOS system. With a starting frequency of 50MHz, the input signal of the dDOS system was swept to 100, 150, 250, or 300MHz in 4MHz increments and results were compared to full 50-300MHz networkanalyzer DOS measurements. The average errors in extracted μa and μs' with dDOS were lowest for the full 50-300MHz sweep (less than 3%) and were within 3.8% for frequency bandwidths as narrow as 50-150MHz. The errors increased to as much as 9.0% when a bandwidth of 50-100MHz was tested. These results demonstrate the possibility for reduced data collection with dDOS without critical compensation of optical property extraction.

  4. Functional imaging using diffuse optical spectroscopy of neoadjuvant chemotherapy response in women with locally advanced breast cancer.

    Science.gov (United States)

    Soliman, Hany; Gunasekara, Anoma; Rycroft, Mary; Zubovits, Judit; Dent, Rebecca; Spayne, Jacqueline; Yaffe, Martin J; Czarnota, Gregory J

    2010-05-01

    Functional imaging with tomographic near-infrared diffuse optical spectroscopy (DOS) can measure tissue concentration of deoxyhemoglobin (Hb), oxyhemoglobin (HbO2), percent water (%water), and scattering power (SP). In this study, we evaluated tumor DOS parameters and described their relationship to clinical and pathologic outcome in patients undergoing neoadjuvant therapy for locally advanced breast cancer. Ten patients were enrolled and intended to undergo five scans each. Scans were taken up to 3 days before treatment and at 1, 4, and 8 weeks after neoadjuvant treatment before surgery. Changes in volume of interest weighted tissue Hb, HbO2, %water, and SP corresponding to the tumor were compared with clinical and pathologic response. All patients' tumor volumes of interest were significantly different compared with background tissue for all parameters. Five patients had a good pathologic response. Four patients were considered nonresponders. One patient initially did not respond to chemotherapy but, after a change in chemotherapy, had a good response. In the five patients with a good response, the mean drop in Hb, HbO2, %water, and SP from baseline to the 4-week scan was 67.6% (SD = 20.8), 58.9% (SD = 20.3), 51.2% (SD = 28.3), and 52.6% (SD = 26.4), respectively. In contrast, the four nonresponders had a mean drop of 17.7% (SD = 9.8), 18.0% (SD = 20.8), 15.4% (SD = 11.7), and 12.6% (SD = 10.2) for Hb, HbO2, %water, and SP, respectively. Responders and nonresponders were significantly different for all functional parameters at the 4-week scan, except for %water, which approached significance. Thus, DOS could be used as an early detector of tumor response. Copyright 2010 AACR.

  5. Non-Invasive Monitoring of Temporal and Spatial Blood Flow during Bone Graft Healing Using Diffuse Correlation Spectroscopy.

    Directory of Open Access Journals (Sweden)

    Songfeng Han

    Full Text Available Vascular infiltration and associated alterations in microvascular blood flow are critical for complete bone graft healing. Therefore, real-time, longitudinal measurement of blood flow has the potential to successfully predict graft healing outcomes. Herein, we non-invasively measure longitudinal blood flow changes in bone autografts and allografts using diffuse correlation spectroscopy in a murine femoral segmental defect model. Blood flow was measured at several positions proximal and distal to the graft site before implantation and every week post-implantation for a total of 9 weeks (autograft n = 7 and allograft n = 10. Measurements of the ipsilateral leg with the graft were compared with those of the intact contralateral control leg. Both autografts and allografts exhibited an initial increase in blood flow followed by a gradual return to baseline levels. Blood flow elevation lasted up to 2 weeks in autografts, but this duration varied from 2 to 6 weeks in allografts depending on the spatial location of the measurement. Intact contralateral control leg blood flow remained at baseline levels throughout the 9 weeks in the autograft group; however, in the allograft group, blood flow followed a similar trend to the graft leg. Blood flow difference between the graft and contralateral legs (ΔrBF, a parameter defined to estimate graft-specific changes, was elevated at 1-2 weeks for the autograft group, and at 2-4 weeks for the allograft group at the proximal and the central locations. However, distal to the graft, the allograft group exhibited significantly greater ΔrBF than the autograft group at 3 weeks post-surgery (p < 0.05. These spatial and temporal differences in blood flow supports established trends of delayed healing in allografts versus autografts.

  6. Classification and quantification analysis of peach kernel from different origins with near-infrared diffuse reflection spectroscopy

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2014-01-01

    Full Text Available Background: Peach kernels which contain kinds of fatty acids play an important role in the regulation of a variety of physiological and biological functions. Objective: To establish an innovative and rapid diffuse reflectance near-infrared spectroscopy (DR-NIR analysis method along with chemometric techniques for the qualitative and quantitative determination of a peach kernel. Materials and Methods: Peach kernel samples from nine different origins were analyzed with high-performance liquid chromatography (HPLC as a reference method. DR-NIR is in the spectral range 1100-2300 nm. Principal component analysis (PCA and partial least squares regression (PLSR algorithm were applied to obtain prediction models, The Savitzky-Golay derivative and first derivative were adopted for the spectral pre-processing, PCA was applied to classify the varieties of those samples. For the quantitative calibration, the models of linoleic and oleinic acids were established with the PLSR algorithm and the optimal principal component (PC numbers were selected with leave-one-out (LOO cross-validation. The established models were evaluated with the root mean square error of deviation (RMSED and corresponding correlation coefficients (R2 . Results: The PCA results of DR-NIR spectra yield clear classification of the two varieties of peach kernel. PLSR had a better predictive ability. The correlation coefficients of the two calibration models were above 0.99, and the RMSED of linoleic and oleinic acids were 1.266% and 1.412%, respectively. Conclusion: The DR-NIR combined with PCA and PLSR algorithm could be used efficiently to identify and quantify peach kernels and also help to solve variety problem.

  7. Visible and Near-Infrared Diffuse Reflectance Spectroscopy for Prediction of Soil Properties near a Copper Smelter

    Institute of Scientific and Technical Information of China (English)

    XIE Xian-Li; PAN Xian-Zhang; SUN Bo

    2012-01-01

    Spatial and temporal monitoring of soil properties in smelting regions requires collection of a large number of samples followed by laboratory cumbersome and time-consuming measurements.Visible and near-infrared diffuse reflectance spectroscopy (VNIR-DRS) provides a rapid and inexpensive tool to predict various soil properties simultaneously.This study evaluated the suitability of VNIR-DRS for predicting soil properties,including organic matter (OM),pH,and heavy metals (Cu,Pb,Zn,Cd,and Fe),using a total of 254 samples collected in soil profiles near a large copper smelter in China.Partial least square regression (PLSR) with cross-validation was used to relate soil property data to the reflectance spectral data by applying different preprocessing strategies.The performance of VNIR-DRS calibration models was evaluated using the coefficient of determination in cross-validation (Rcv2) and the ratio of standard deviation to the root mean standard error of cross-validation (SD/RMSEcv).The models provided fairly accurate predictions for OM and Fe (Rcv2 > 0.80,SD/RMSEcv > 2.00),less accurate but acceptable for screening purposes for pH,Cu,Pb,and Cd (050 < Rcv2 < 0.80,1.40 < SD/RMSEcv < 2.00),and poor accuracy for Zn (Rcv2< 0.50,SD/RMSEcv < 1.40).Because soil properties in contaminated areas generally show large variation,a comparative large number of calibrating samples,which are variable enough and uniformly distributed,are necessary to create more accurate and robust VNIR-DRS calibration models.This study indicated that VNIR-DRS technique combined with continuously enriched soil spectral library could be a nondestructive alternative for soil environment monitoring.

  8. In Vivo, Non-Invasive Characterization of Human Bone by Hybrid Broadband (600-1200 nm) Diffuse Optical and Correlation Spectroscopies

    Science.gov (United States)

    Pagliazzi, Marco; Negredo, Eugènia; Martelli, Fabrizio; Farina, Andrea; Dalla Mora, Alberto; Lindner, Claus; Farzam, Parisa; Pérez-Álvarez, Núria; Puig, Jordi; Taroni, Paola; Pifferi, Antonio; Durduran, Turgut

    2016-01-01

    Non-invasive in vivo diffuse optical characterization of human bone opens a new possibility of diagnosing bone related pathologies. We present an in vivo characterization performed on seventeen healthy subjects at six different superficial bone locations: radius distal, radius proximal, ulna distal, ulna proximal, trochanter and calcaneus. A tailored diffuse optical protocol for high penetration depth combined with the rather superficial nature of considered tissues ensured the effective probing of the bone tissue. Measurements were performed using a broadband system for Time-Resolved Diffuse Optical Spectroscopy (TRS) to assess mean absorption and reduced scattering spectra in the 600–1200 nm range and Diffuse Correlation Spectroscopy (DCS) to monitor microvascular blood flow. Significant variations among tissue constituents were found between different locations; with radius distal rich of collagen, suggesting it as a prominent location for bone related measurements, and calcaneus bone having highest blood flow among the body locations being considered. By using TRS and DCS together, we are able to probe the perfusion and oxygen consumption of the tissue without any contrast agents. Therefore, we predict that these methods will be able to evaluate the impairment of the oxygen metabolism of the bone at the point-of-care. PMID:27997565

  9. Probing of Charge Transfer States at Buried Organic Interfaces with Even-Order Spectroscopy

    Science.gov (United States)

    Pandey, Ravindra; Moon, Aaron; Roberts, Sean

    Organic thin film photovoltaics (OPV) are an emerging economically competitive technology that combines manufacturing adaptability, low-cost processing and a lightweight, flexible device end-product. At junctions formed between organic electron-donating and electron-accepting materials, the abrupt change in the dielectric properties can strongly perturb the density of states of the OPV. This can substantially alter the driving force for charge transfer between these materials. Electronic Sum Frequency Generation (ESFG), owing to its inherent interfacial sensitivity, is ideally suited to probe buried interfaces. Here, we report the ESFG spectra of Copper Phthalocyanine (CuPc) films, deposited on SiO2 measured for both reflection and transmission geometries. Three peaks are observed that roughly correlate with resonances that comprise CuPc's Q-band absorption but display slight shifts and amplitude changes with respect to CuPc's bulk absorption spectrum. Experimental results are compared with calculations based on a thin film interference model that accounts for ESFG emitted from both the CuPc:Air and CuPc:SiO2 interface as well as contributions to the signal from higher order source terms from the bulk. The model reveals a difference in the density of states between the two interfaces and suggests that by combining experimental transmission and reflection data it is possible to separate bulk and interfacial contributions to ESFG spectra.

  10. Thermal diffusion of chlorine in uranium dioxide studied by secondary ion mass spectrometry and X-ray absorption spectroscopy

    Science.gov (United States)

    Pipon, Y.; Toulhoat, N.; Moncoffre, N.; Raimbault, L.; Scheidegger, A. M.; Farges, F.; Carlot, G.

    2007-05-01

    In a nuclear reactor, 35Cl present as an impurity in the nuclear fuel is activated by thermal neutron capture. During interim storage or geological disposal of the nuclear fuel, 36Cl may be released from the fuel to the geo/biosphere and contribute significantly to the 'instant release fraction'. In order to elucidate the diffusion mechanisms, both irradiation and thermal effects must be assessed. This paper deals with the thermal diffusion of chlorine in depleted UO2. For this purpose, sintered UO2 pellets were implanted with 37Cl at an ion fluence of 1013 cm-2 and successively annealed in the 1175-1475 K temperature range. The implanted chlorine is used to simulate the behaviour of the displaced one due to recoil and to interactions with the fission fragments during reactor operation. The behaviour of the pristine and the implanted chlorine was investigated during thermal annealing. SIMS and μ-XAS (at the Cl-K edge) analyses show that: the thermal migration of implanted chlorine becomes significant at 1275 K; this temperature and the calculated activation energy of 4.3 eV points out the great ability of chlorine to migrate in UO2 at relatively low temperatures, the behaviour of the implanted chlorine which aggregates into 'hot spots' during annealing before its effusion is clearly different from that of the pristine one which remains homogenously distributed after annealing, the 'hot spot' and the pristine chlorine seem to be in different structural environments. Both types of chlorine are assumed to have a valence state of -I, the comparison between an U2O2Cl5 reference compound and the pristine chlorine environment shows a contribution of the U2O2Cl5 to the pristine chlorine.

  11. Novel electronic ferroelectricity in an organic charge-order insulator investigated with terahertz-pump optical-probe spectroscopy

    Science.gov (United States)

    Yamakawa, H.; Miyamoto, T.; Morimoto, T.; Yada, H.; Kinoshita, Y.; Sotome, M.; Kida, N.; Yamamoto, K.; Iwano, K.; Matsumoto, Y.; Watanabe, S.; Shimoi, Y.; Suda, M.; Yamamoto, H. M.; Mori, H.; Okamoto, H.

    2016-02-01

    In electronic-type ferroelectrics, where dipole moments produced by the variations of electron configurations are aligned, the polarization is expected to be rapidly controlled by electric fields. Such a feature can be used for high-speed electric-switching and memory devices. Electronic-type ferroelectrics include charge degrees of freedom, so that they are sometimes conductive, complicating dielectric measurements. This makes difficult the exploration of electronic-type ferroelectrics and the understanding of their ferroelectric nature. Here, we show unambiguous evidence for electronic ferroelectricity in the charge-order (CO) phase of a prototypical ET-based molecular compound, α-(ET)2I3 (ET:bis(ethylenedithio)tetrathiafulvalene), using a terahertz pulse as an external electric field. Terahertz-pump second-harmonic-generation(SHG)-probe and optical-reflectivity-probe spectroscopy reveal that the ferroelectric polarization originates from intermolecular charge transfers and is inclined 27° from the horizontal CO stripe. These features are qualitatively reproduced by the density-functional-theory calculation. After sub-picosecond polarization modulation by terahertz fields, prominent oscillations appear in the reflectivity but not in the SHG-probe results, suggesting that the CO is coupled with molecular displacements, while the ferroelectricity is electronic in nature. The results presented here demonstrate that terahertz-pump optical-probe spectroscopy is a powerful tool not only for rapidly controlling polarizations, but also for clarifying the mechanisms of ferroelectricity.

  12. High-resolution Reflection Spectroscopy of Cs D2 Line Studied by High-order-harmonic Detection

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yanting; MA Weiguang; XIAO Liantuan; LI Changyong; ZHANG Linjie; JIA Suotang

    2002-01-01

    In this paper, by numerical analysis the relationship of the modulation broaden index with modulation index using high-order-harmonic detection is investigated. Using the voltage modulation the 2f,4f and 6f harmonic signals about the reflection spectroscopy of 6S1/2(F=4)→6P3/2 transition of the cesium D2 line are also be measured. The experimental results are in good agreement with the theoretical predictions. It is found that narrower line-width can be achieved by higher-harmonic detection than the line-width detected by direct absorption when the modulation index is smaller than 1.81, 2.98 and 4.14 for 2f, 4f, and 6f signals, respectively.

  13. Molecular Organization of Various Collagen Fragments as Revealed by Atomic Force Microscopy and Diffusion-Ordered NMR Spectroscopy

    NARCIS (Netherlands)

    Stötzel, S.; Schurink, M.; Wienk, H.L.J.; Siebler, U.; Burg-Roderfeld, M.; Eckert, T.; Kulik, B.; Wechselberger, R.W.; Sewing, J.; Steinmeyer, J.; Oesser, S.; Boelens, R.; Siebert, H.-C.

    2012-01-01

    Heterogeneous mixtures of collagen fragments can be used as nutrition supplement or as key ingredients for ointments with therapeutic relevance in wound healing. Some mixtures of collagen fragments are referred to as collagen hydrolysates owing to the production process with hydrolytic enzymes. Sinc

  14. Noninvasive quantification of postocclusive reactive hyperemia in mouse thigh muscle by near-infrared diffuse correlation spectroscopy.

    Science.gov (United States)

    Cheng, Ran; Zhang, Xiaoyan; Daugherty, Alan; Shin, Hainsworth; Yu, Guoqiang

    2013-10-20

    Many vasculature-related diseases affecting skeletal muscle function have been studied in mouse models. Noninvasive quantification of muscle blood flow responses during postocclusive reactive hyperemia (PORH) is often used to evaluate vascular function in human skeletal muscles. However, blood flow measurements during PORH in small skeletal muscles of mice are rare due to the lack of appropriate technologies coupled with the challenge of measurement setup resulting from the lack of large enough test sites. In this study, we explored adapting diffuse correlation spectroscopy (DCS) for noninvasive measurement of the relative changes of blood flow (rBF) in mouse thigh muscles during PORH. A small fiber-optic probe was designed and glued on the mouse thigh to reduce the motion artifact induced by the occlusion procedure. Arterial occlusion was created by tying a polyvinyl chloride (PVC) tube around the mouse thigh while the muscle rBF was continuously monitored by DCS to ensure the success of the occlusion. After 5 min, the occlusion was rapidly released by severing the PVC tube using a cautery pen. Typical rBF responses during PORH were observed in all mice (n=7), which are consistent with those observed by arterial-spin-labeled magnetic resonance imaging (ASL-MRI) as reported in the literature. On average, rBF values from DCS during occlusion were lower than 10% (3.1±2.2%) of the baseline values (assigning 100%), indicating the success of arterial occlusion in all mice. Peak values of rBF during PORH measured by the DCS (357.6±36.3%) and ASL-MRI (387.5±150.0%) were also similar whereas the values of time-to-peak (the time duration from the end of occlusion to the peak rBF) were quite different (112.6±35.0  s versus 48.0±27.0  s). Simultaneous measurements by these two techniques are needed to identify the factors that may cause such discrepancy. This study highlights the utility of DCS technology to quantitatively evaluate tissue blood flow responses

  15. Application of VNIR diffuse reflectance spectroscopy for mapping of organic matter redistribution due to erosion and deposition processes

    Science.gov (United States)

    Klement, Ales; Brodsky, Lukas; Jaksik, Ondrej; Fer, Miroslav; Kodesova, Radka

    2014-05-01

    Visible and near-infrared (VNIR) diffuse reflectance spectroscopy is cost- and time-effective and environmentally friendly techniques method used for prediction of soil properties. Study was performed on the soils from the agricultural land from the municipalities of Brumovice (209 samples), Sedlcany (67 samples), Vidim (74 samples) and Zelezna (32 samples). In Brumovice original soil type was Haplic Chernozem on loess, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). A similar process has been described at other three locations Sedlcany, Vidim and Zelezna where the original soil types were Haplic Cambisol on gneiss, Haplic Luvisol on loess and Haplic Cambisol on shales, respectively. The goal of the study was to evaluate relationship between soil spectra curves and organic matter content to provide an efficient tool for mapping of organic matter redistribution (i.e. soil degradation) due to erosion and deposition processes. Samples were taken from the topsoil within regular grid covering studied areas. The soil spectra curves (of air dry soil and sieved using 0.2 mm sieve) were measured in the laboratory using spectrometer FieldSpec®3 (350 - 2 500 nm). Partial least squares regression (PLSR) was used for modeling of the relationship between spectra and measured organic matter content. Prediction ability was evaluated using the R2, root mean square error (RMSE). The results showed the best prediction of the organic matter content was obtained for soil samples from Brumovice (R2 = 0.78, RMSE = 0.15) and decreased as follows: Zelezna (R2 = 0.68, RMSE = 0.23), Sedlcany (R2 = 0.64, RMSE = 0.18) and Vidim (R2 = 0.61, RMSE = 0.12). In general, the results confirmed that the measurement of soil spectral characteristics is a promising technology for a digital soil mapping and predicting studied soil properties. Acknowledgment: Authors acknowledge the financial support of the Ministry of Agriculture of

  16. Impedance spectroscopy of highly ordered nano-porous electrodes based on Au-AAO (anodic aluminum oxide) structure.

    Science.gov (United States)

    Ahn, Jaehwan; Cho, Sungbo; Min, Junhong

    2013-11-01

    Electrochemical measurements using the microelectrodes are increasingly utilized for the label-free detection of the small amount of biological materials such as DNA, protein, and cells. However, the interfacial electrode impedance increases and may hinder the detection of weak signals as the size of electrode decreases. To enhance the measurement sensitivity while reducing the electrode size, in this study, microelectrodes employing a nanoporous structure were fabricated and characterized by using electrical impedance spectroscopy. We made the highly ordered honeycomb nanoporous structure of Anodic Aluminum Oxide (AAO) by electrochemical anodizing and formed Au layer on the surface of AAO (Au/AAO) by electroless Au plating method. The electrical characteristics of the fabricated Au/AAO electrodes were evaluated by using de Levie's model derived for the pore electrodes. As a result, the interfacial electrode impedance of the fabricated Au/AAO electrodes was 2-3 order lower than the value of the planar electrodes at frequencies below 1 kHz. It implies this nanoporous electrode could be directly applied to label free detection of biomaterials.

  17. MR spectroscopy and diffusion tensor imaging of the brain in congenital muscular dystrophy with merosin deficiency: metabolite level decreases, fractional anisotropy decreases, and apparent diffusion coefficient increases in the white matter.

    Science.gov (United States)

    Sijens, P E; Fock, J M; Meiners, L C; Potze, J H; Irwan, R; Oudkerk, M

    2007-06-01

    Brain magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in one patient with merosin-deficient congenital muscular dystrophy (MDCMD) revealed significant metabolite (choline, creatine, N-acetyl aspartate) level reductions, fractional anisotropy (FA) reduction and increased apparent diffusion coefficient (ADC) in the white matter (p<0.01, all). In the gray matter, the MRS properties did not differ significantly from those in controls. The ADC and FA, however, differed significantly as in the white matter, although the differences were less pronounced. This is the first quantitative MR study of the brain in a patient with MDCMD, which revealed that the concentrations of all MRS measured metabolites were decreased only in the white matter. This observation, combined with the DTI observed ADC increases and FA decrease, indicated a presence of vasogenic edema in the white matter.

  18. Influence of relaxation of the atomic order in f.c.c.-Ni-Al alloys on X-ray diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bokoch, S.M.; Kulish, M.P. [Taras Shevchenko Kyyiv National University (Ukraine); Leonov, D.S.; Kunitsky, Yu.A. [Technical Centre, N.A.S.U., Kyyiv (Ukraine); Tatarenko, V.A. [G.V. Kurdyumov Institute for Metal Physics, N.A.S.U., Kyyiv (Ukraine)

    2009-08-15

    The atomic short-range order (SRO) for the substitutional f.c.c.-Ni-9 at.% Al single-crystal solution is investigated using the X-ray diffuse-scattering method (supplemented by Monte Carlo simulation studies) and analyzing the salient features of the second-order phonon diffuse scattering of X-rays. As shown, in quenched state, the SRO corresponds to the presence in alloy of the static concentration waves with k{sub X}(001) and k(000.2) wave vectors. Initial SRO-kinetics stage is attended by the noticeable increasing of the diffuse-scattering intensities for wave vectors close to structural (Bragg) reflexes. Parameters of the time dependence of X-ray diffuse-scattering intensity for f.c.c.-Ni-9 at.% Al alloy (after quenching) at low annealing temperature (373 K) are significantly different for different wave vectors generating the ordering and/or clustering processes. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. Thermal diffusion of chlorine in uranium dioxide studied by secondary ion mass spectrometry and X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pipon, Y. [Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France)]. E-mail: pipon@ipnl.in2p3.fr; Toulhoat, N. [Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Commissariat l' Energie Atomique (CEA), DEN/Saclay, 91191 Gif s/Yvette Cedex (France); Moncoffre, N. [Institut de Physique Nucleaire de Lyon (IPNL), 4, rue Enrico Fermi, 69622 Villeurbanne cedex (France); Raimbault, L. [Centre d' Informatique Geologique (CIG), Ecole des Mines, 35 rue Saint Honore, F-77305 Fontainebleau cedex (France); Scheidegger, A.M. [Laboratory for Waste Management, Nuclear Energy and Safety Department (NES), Paul Scherrer Institut CH-5232 Villigen PSI (Switzerland); Farges, F. [Laboratoire des Geomateriaux, Universite de Marne la Vallee, 5 Bd Descartes-Champs S/Marne, 77454 Marne la Vallee cedex 2 (France); Carlot, G. [Commissariat l' Energie Atomique (CEA), Centre de Cadarache, DEN/DEC/SESC/LLCC, 13108 Saint-Paul lez Durance (France)

    2007-05-31

    In a nuclear reactor, {sup 35}Cl present as an impurity in the nuclear fuel is activated by thermal neutron capture. During interim storage or geological disposal of the nuclear fuel, {sup 36}Cl may be released from the fuel to the geo/biosphere and contribute significantly to the 'instant release fraction'. In order to elucidate the diffusion mechanisms, both irradiation and thermal effects must be assessed. This paper deals with the thermal diffusion of chlorine in depleted UO{sub 2}. For this purpose, sintered UO{sub 2} pellets were implanted with {sup 37}Cl at an ion fluence of 10{sup 13}cm{sup -2} and successively annealed in the 1175-1475K temperature range. The implanted chlorine is used to simulate the behaviour of the displaced one due to recoil and to interactions with the fission fragments during reactor operation. The behaviour of the pristine and the implanted chlorine was investigated during thermal annealing. SIMS and {mu}-XAS (at the Cl-K edge) analyses show that: (1) the thermal migration of implanted chlorine becomes significant at 1275K; this temperature and the calculated activation energy of 4.3eV points out the great ability of chlorine to migrate in UO{sub 2} at relatively low temperatures; (2) the behaviour of the implanted chlorine which aggregates into 'hot spots' during annealing before its effusion is clearly different from that of the pristine one which remains homogenously distributed after annealing; (3) the 'hot spot' and the pristine chlorine seem to be in different structural environments. Both types of chlorine are assumed to have a valence state of -I; (4) the comparison between an U{sub 2}O{sub 2}Cl{sub 5} reference compound and the pristine chlorine environment shows a contribution of the U{sub 2}O{sub 2}Cl{sub 5} to the pristine chlorine.

  20. High-order finite-volume solutions of the steady-state advection-diffusion equation with nonlinear Robin boundary conditions

    Science.gov (United States)

    Lin, Zhi; Zhang, Qinghai

    2017-09-01

    We propose high-order finite-volume schemes for numerically solving the steady-state advection-diffusion equation with nonlinear Robin boundary conditions. Although the original motivation comes from a mathematical model of blood clotting, the nonlinear boundary conditions may also apply to other scientific problems. The main contribution of this work is a generic algorithm for generating third-order, fourth-order, and even higher-order explicit ghost-filling formulas to enforce nonlinear Robin boundary conditions in multiple dimensions. Under the framework of finite volume methods, this appears to be the first algorithm of its kind. Numerical experiments on boundary value problems show that the proposed fourth-order formula can be much more accurate and efficient than a simple second-order formula. Furthermore, the proposed ghost-filling formulas may also be useful for solving other partial differential equations.

  1. Derivation of Threshold Values for Groundwater in Romania, in order to distinguish Point & Diffuse pollution from natural background levels

    NARCIS (Netherlands)

    Schipper, P.N.M.; Radu, E.; Vliegenthart, F.; Balaet, R.

    2010-01-01

    Romania aims to adopt and implement the European Union's legislation, also including that for the field of water management. Like other countries, groundwater in Romania is locally polluted from point sources, such as leaking landfills, as well as from diffuse pollution sources, include fertilizers,

  2. Evaluation of higher-order time-domain perturbation theory of photon diffusion on breast-equivalent phantoms and optical mammograms.

    Science.gov (United States)

    Grosenick, D; Kummrow, A; Macdonald, R; Schlag, P M; Rinneberg, H

    2007-12-01

    Time-domain perturbation theory of photon diffusion up to third order was evaluated for its accuracy in deducing optical properties of breast tumors using simulated and physical phantoms and by analyzing 141 projection mammograms of 87 patients with histology-validated tumors that had been recorded by scanning time-domain optical mammography. The slightly compressed breast was modeled as (partially) homogeneous diffusely scattering infinite slab containing a scattering and absorbing spherical heterogeneity representing the tumor. Photon flux densities were calculated from densities of transmitted photons, assuming extended boundary conditions. Explicit formulas are provided for second-order changes in transmitted photon density due to the presence of absorbers or scatterers. The results on phantoms obtained by perturbation theory carried up to third order were compared with measured temporal point spread functions, with numerical finite-element method (FEM) simulations of transmitted photon flux density, with results obtained from the diffraction of diffuse photon density waves, and from Padé approximants. The breakdown of first-, second-, and third-order perturbation theory is discussed for absorbers and a general expression was derived for the convergence of the Born series in this case. Taking tumor optical properties derived by the diffraction model as reference we conclude that estimates of tumor absorption coefficients by perturbation theory agree with reference values within +/-25% in only 65% (first order), 66% (second order), and 77% (third order) of all mammograms analyzed. In the remaining cases tumor absorption is generally underestimated due to the breakdown of perturbation theory. On average the empirical Padé approximants yield tumor absorption coefficients similar to third-order perturbation theory, yet at noticeable lower computational efforts.

  3. Communication: Development of standing evanescent-wave fluorescence correlation spectroscopy and its application to the lateral diffusion of lipids in a supported lipid bilayer

    Science.gov (United States)

    Otosu, Takuhiro; Yamaguchi, Shoichi

    2017-07-01

    We present standing evanescent-wave fluorescence correlation spectroscopy (SEW-FCS). This technique utilizes the interference of two evanescent waves which generates a standing evanescent-wave. Fringe-pattern illumination created by a standing evanescent-wave enables us to measure the diffusion coefficients of molecules with a super-resolution corresponding to one fringe width. Because the fringe width can be reliably estimated by a simple procedure, utilization of fringes is beneficial to quantitatively analyze the slow diffusion of molecules in a supported lipid bilayer (SLB), a model biomembrane formed on a solid substrate, with the timescale relevant for reliable FCS analysis. Furthermore, comparison of the data between SEW-FCS and conventional total-internal reflection FCS, which can also be performed by the SEW-FCS instrument, effectively eliminates the artifact due to afterpulsing of the photodiode detector. The versatility of SEW-FCS is demonstrated by its application to various SLBs.

  4. ACA-Pro: calibration protocol for quantitative diffuse reflectance spectroscopy. Validation on contact and noncontact probe- and CCD-based systems

    Science.gov (United States)

    Sorgato, Veronica; Berger, Michel; Emain, Charlotte; Vever-Bizet, Christine; Dinten, Jean-Marc; Bourg-Heckly, Geneviève; Planat-Chrétien, Anne

    2016-06-01

    We have developed an adaptive calibration algorithm and protocol (ACA-Pro) that corrects from the instrumental response of various spatially resolved diffuse reflectance spectroscopy (DRSsr) systems to enable the quantification of absorption and scattering properties based on a Monte Carlo-based look-up-table approach. The protocol involves the use of a calibration reference base built with measurements of a range of different diffusive intralipid phantoms. Moreover, an advanced strategy was established to take into account the experimental variations with an additional measurement of a common solid material, allowing the use of a single calibration reference base for all experiments. The ACA-Pro is validated in contact and noncontact probe-based DRSsr systems. Furthermore, the first results of a setup replacing the probe with a CCD detector are shown to confirm the robustness of the approach.

  5. X-ray and Electrochemical Impedance Spectroscopy Diagnostic Investigations of Liquid Water in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers

    Science.gov (United States)

    Antonacci, Patrick

    In this thesis, electrochemical impedance spectroscopy (EIS) and synchrotron x-ray radiography were utilized to characterize the impact of liquid water distributions in polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs) on fuel cell performance. These diagnostic techniques were used to quantify the effects of liquid water visualized on equivalent resistances measured through EIS. The effects of varying the thickness of the microporous layer (MPL) of GDLs were studied using these diagnostic techniques. In a first study on the feasibility of this methodology, two fuel cell cases with a 100 microm-thick and a 150 microm-thick MPL were compared under constant current density operation. In a second study with 10, 30, 50, and 100 microm-thick MPLs, the liquid water in the cathode substrate was demonstrated to affect mass transport resistance, while the liquid water content in the anode (from back diffusion) affected membrane hydration, evidenced through ohmic resistance measurements.

  6. Atomic oxygen in a cold argon plasma jet: TALIF spectroscopy in ambient air with modelling and measurements of ambient species diffusion

    Science.gov (United States)

    Reuter, S.; Winter, J.; Schmidt-Bleker, A.; Schroeder, D.; Lange, H.; Knake, N.; Schulz-von der Gathen, V.; Weltmann, K.-D.

    2012-04-01

    By investigating the atomic oxygen density in its effluent, two-photon absorption laser-induced fluorescence (TALIF) spectroscopy measurements are for the first time performed in a cold argon/oxygen atmospheric pressure plasma jet. The measurements are carried out in ambient air and quenching by inflowing air species is considered. We propose a novel absorption technique in the VUV spectral range, where emission originating from within the discharge is used as light source to determine the inflow of atmospheric oxygen into the effluent. Furthermore, we propose a modelling solution for the on-axis density of inflowing ambient air based on the stationary convection-diffusion equation.

  7. HELIOS—A laboratory based on high-order harmonic generation of extreme ultraviolet photons for time-resolved spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Plogmaker, S., E-mail: Stefan.Plogmaker@physics.uu.se, E-mail: Joachim.Terschluesen@physics.uu.se, E-mail: Johan.Soderstrom@physics.uu.se; Terschlüsen, J. A., E-mail: Stefan.Plogmaker@physics.uu.se, E-mail: Joachim.Terschluesen@physics.uu.se, E-mail: Johan.Soderstrom@physics.uu.se; Krebs, N.; Svanqvist, M.; Forsberg, J.; Cappel, U. B.; Rubensson, J.-E.; Siegbahn, H.; Söderström, J., E-mail: Stefan.Plogmaker@physics.uu.se, E-mail: Joachim.Terschluesen@physics.uu.se, E-mail: Johan.Soderstrom@physics.uu.se [Department of Physics and Astronomy, Molecular and Condensed Matter Physics, Uppsala University, P.O. Box 516, 75120 Uppsala (Sweden)

    2015-12-15

    In this paper, we present the HELIOS (High Energy Laser Induced Overtone Source) laboratory, an in-house high-order harmonic generation facility which generates extreme ultraviolet (XUV) photon pulses in the range of 15-70 eV with monochromatized XUV pulse lengths below 35 fs. HELIOS is a source for time-resolved pump-probe/two-color spectroscopy in the sub-50 fs range, which can be operated at 5 kHz or 10 kHz. An optical parametric amplifier is available for pump-probe experiments with wavelengths ranging from 240 nm to 20 000 nm. The produced XUV radiation is monochromatized by a grating in the so-called off-plane mount. Together with overall design parameters, first monochromatized spectra are shown with an intensity of 2 ⋅ 10{sup 10} photons/s (at 5 kHz) in the 29th harmonic, after the monochromator. The XUV pulse duration is measured to be <25 fs after monochromatization.

  8. Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy.

    Science.gov (United States)

    Wenner, Sigurd; Jones, Lewys; Marioara, Calin D; Holmestad, Randi

    2017-05-01

    Scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDS) is a common technique for chemical mapping in thin samples. Obtaining high-resolution elemental maps in the STEM is jointly dependent on stepping the sharply focused electron probe in a precise raster, on collecting a significant number of characteristic X-rays over time, and on avoiding damage to the sample. In this work, 80kV aberration-corrected STEM-EDS mapping was performed on ordered precipitates in aluminium alloys. Probe and sample instability problems are handled by acquiring series of annular dark-field (ADF) images and simultaneous EDS volumes, which are aligned and non-rigidly registered after acquisition. The summed EDS volumes yield elemental maps of Al, Mg, Si, and Cu, with sufficient resolution and signal-to-noise ratio to determine the elemental species of each atomic column in a periodic structure, and in some cases the species of single atomic columns. Within the uncertainty of the technique, S and β" phases were found to have pure elemental atomic columns with compositions Al2CuMg and Al2Mg5Si4, respectively. The Q' phase showed some variation in chemistry across a single precipitate, although the majority of unit cells had a composition Al6Mg6Si7.2Cu2.

  9. HELIOS—A laboratory based on high-order harmonic generation of extreme ultraviolet photons for time-resolved spectroscopy

    Science.gov (United States)

    Plogmaker, S.; Terschlüsen, J. A.; Krebs, N.; Svanqvist, M.; Forsberg, J.; Cappel, U. B.; Rubensson, J.-E.; Siegbahn, H.; Söderström, J.

    2015-12-01

    In this paper, we present the HELIOS (High Energy Laser Induced Overtone Source) laboratory, an in-house high-order harmonic generation facility which generates extreme ultraviolet (XUV) photon pulses in the range of 15-70 eV with monochromatized XUV pulse lengths below 35 fs. HELIOS is a source for time-resolved pump-probe/two-color spectroscopy in the sub-50 fs range, which can be operated at 5 kHz or 10 kHz. An optical parametric amplifier is available for pump-probe experiments with wavelengths ranging from 240 nm to 20 000 nm. The produced XUV radiation is monochromatized by a grating in the so-called off-plane mount. Together with overall design parameters, first monochromatized spectra are shown with an intensity of 2 ṡ 1010 photons/s (at 5 kHz) in the 29th harmonic, after the monochromator. The XUV pulse duration is measured to be <25 fs after monochromatization.

  10. HELIOS--A laboratory based on high-order harmonic generation of extreme ultraviolet photons for time-resolved spectroscopy.

    Science.gov (United States)

    Plogmaker, S; Terschlüsen, J A; Krebs, N; Svanqvist, M; Forsberg, J; Cappel, U B; Rubensson, J-E; Siegbahn, H; Söderström, J

    2015-12-01

    In this paper, we present the HELIOS (High Energy Laser Induced Overtone Source) laboratory, an in-house high-order harmonic generation facility which generates extreme ultraviolet (XUV) photon pulses in the range of 15-70 eV with monochromatized XUV pulse lengths below 35 fs. HELIOS is a source for time-resolved pump-probe/two-color spectroscopy in the sub-50 fs range, which can be operated at 5 kHz or 10 kHz. An optical parametric amplifier is available for pump-probe experiments with wavelengths ranging from 240 nm to 20,000 nm. The produced XUV radiation is monochromatized by a grating in the so-called off-plane mount. Together with overall design parameters, first monochromatized spectra are shown with an intensity of 2 ⋅ 10(10) photons/s (at 5 kHz) in the 29th harmonic, after the monochromator. The XUV pulse duration is measured to be <25 fs after monochromatization.

  11. Adding diffuse reflectance infrared Fourier transform spectroscopy capability to extended x-ray-absorption fine structure in a new cell to study solid catalysts in combination with a modulation approach

    Science.gov (United States)

    Chiarello, Gian Luca; Nachtegaal, Maarten; Marchionni, Valentina; Quaroni, Luca; Ferri, Davide

    2014-07-01

    We describe a novel cell used to combine in situ transmission X-ray absorption spectroscopy (XAS) with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in a single experiment. The novelty of the cell design compared to current examples is that both radiations are passed through an X-ray and IR transparent window in direct contact with the sample. This innovative geometry also offers a wide surface for IR collection. In order to avoid interference from the crystalline IR transparent materials (e.g., CaF2, MgF2, diamond) a 500 μm carbon filled hole is laser drilled in the center of a CaF2 window. The cell is designed to represent a plug flow reactor, has reduced dead volume in order to allow for fast exchange of gases and is therefore suitable for experiments under fast transients, e.g., according to the concentration modulation approach. High quality time-resolved XAS and DRIFTS data of a 2 wt.% Pt/Al2O3 catalyst are obtained in concentration modulation experiments where CO (or H2) pulses are alternated to O2 pulses at 150 °C. We show that additional information can be obtained on the Pt redox dynamic under working conditions thanks to the improved sensitivity given by the modulation approach followed by Phase Sensitive Detection (PSD) analysis. It is anticipated that the design of the novel cell is likely suitable for a number of other in situ spectroscopic and diffraction methods.

  12. Prognostic value of brain proton MR spectroscopy and diffusion tensor imaging in newborns with hypoxic-ischemic encephalopathy treated by brain cooling

    Energy Technology Data Exchange (ETDEWEB)

    Ancora, G. [Neonatal Intensive Care Unit, Department of Mother and Infant Infermi Hospital of Rimini, Rimini (Italy); Testa, C.; Tonon, C.; Manners, D.N.; Gramegna, L.L.; Lodi, R. [Department of Biomedical and Neuromotor Sciences University of Bologna, MR Functional Unit, Bologna (Italy); Grandi, S.; Sbravati, F.; Savini, S.; Corvaglia, L.T.; Faldella, G. [University of Bologna, Neonatology Unit, Department of Woman, Child and Adolescent Health, Bologna (Italy); Tani, G. [University of Bologna, Radiology Unit, Department of Woman, Child and Adolescent Health, Bologna (Italy); Malucelli, E. [University of Bologna, Department of Pharmacy and Biotechnologies, Bologna (Italy)

    2013-08-15

    MRI, proton magnetic resonance spectroscopy ({sup 1}H-MRS), and diffusion tensor imaging (DTI) have been shown to be of great prognostic value in term newborns with moderate-severe hypoxic-ischemic encephalopathy (HIE). Currently, no data are available on {sup 1}H-MRS and DTI performed in the subacute phase after hypothermic treatment. The aim of the present study was to assess their prognostic value in newborns affected by moderate-severe HIE and treated with selective brain cooling (BC). Twenty infants treated with BC underwent conventional MRI and {sup 1}H-MRS at a mean (SD) age of 8.3 (2.8) days; 15 also underwent DTI. Peak area ratios of metabolites and DTI variables, namely mean diffusivity (MD), axial and radial diffusivity, and fractional anisotropy (FA), were calculated. Clinical outcome was monitored until 2 years of age. Adverse outcome was observed in 6/20 newborns. Both {sup 1}H-MRS and DTI variables showed higher prognostic accuracy than conventional MRI. N-acetylaspartate/creatine at a basal ganglia localisation showed 100 % PPV and 93 % NPV for outcome. MD showed significantly decreased values in many regions of white and gray matter, axial diffusivity showed the best predictive value (PPV and NPV) in the genu of corpus callosum (100 and 91 %, respectively), and radial diffusivity was significantly decreased in fronto white matter (FWM) and fronto parietal (FP) WM. The decrement of FA showed the best AUC (0.94) in the FPWM. Selective BC in HIE neonates does not affect the early and accurate prognostic value of {sup 1}H-MRS and DTI, which outperform conventional MRI. (orig.)

  13. Green method by diffuse reflectance infrared spectroscopy and spectral region selection for the quantification of sulphamethoxazole and trimethoprim in pharmaceutical formulations

    Directory of Open Access Journals (Sweden)

    Fabiana E.B. da Silva

    2016-03-01

    Full Text Available An alternative method for the quantification of sulphametoxazole (SMZ and trimethoprim (TMP using diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS and partial least square regression (PLS was developed. Interval Partial Least Square (iPLS and Synergy Partial Least Square (siPLS were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. Fifteen commercial tablet formulations and forty-nine synthetic samples were used. The ranges of concentration considered were 400 to 900 mg g-1SMZ and 80 to 240 mg g-1 TMP. Spectral data were recorded between 600 and 4000 cm-1 with a 4 cm-1 resolution by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS. The proposed procedure was compared to high performance liquid chromatography (HPLC. The results obtained from the root mean square error of prediction (RMSEP, during the validation of the models for samples of sulphamethoxazole (SMZ and trimethoprim (TMP using siPLS, demonstrate that this approach is a valid technique for use in quantitative analysis of pharmaceutical formulations. The selected interval algorithm allowed building regression models with minor errors when compared to the full spectrum PLS model. A RMSEP of 13.03 mg g-1for SMZ and 4.88 mg g-1 for TMP was obtained after the selection the best spectral regions by siPLS.

  14. Discrimination of various paper types using diffuse reflectance ultraviolet-visible near-infrared (UV-Vis-NIR) spectroscopy: forensic application to questioned documents.

    Science.gov (United States)

    Kumar, Raj; Kumar, Vinay; Sharma, Vishal

    2015-06-01

    Diffuse reflectance ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy is applied as a means of differentiating various types of writing, office, and photocopy papers (collected from stationery shops in India) on the basis of reflectance and absorbance spectra that otherwise seem to be almost alike in different illumination conditions. In order to minimize bias, spectra from both sides of paper were obtained. In addition, three spectra from three different locations (from one side) were recorded covering the upper, middle, and bottom portions of the paper sample, and the mean average reflectivity of both the sides was calculated. A significant difference was observed in mean average reflectivity of Side A and Side B of the paper using Student's pair >t-test. Three different approaches were used for discrimination: (1) qualitative features of the whole set of samples, (2) principal component analysis, and (3) a combination of both approaches. On the basis of the first approach, i.e., qualitative features, 96.49% discriminating power (DP) was observed, which shows highly significant results with the UV-Vis-NIR technique. In the second approach the discriminating power is further enhanced by incorporating the principal component analysis (PCA) statistical method, where this method describes each UV-Vis spectrum in a group through numerical loading values connected to the first few principal components. All components described 100% variance of the samples, but only the first three PCs are good enough to explain the variance (PC1 = 51.64%, PC2 = 47.52%, and PC3 = 0.54%) of the samples; i.e., the first three PCs described 99.70% of the data, whereas in the third approach, the four samples, C, G, K, and N, out of a total 19 samples, which were not differentiated using qualitative features (approach no. 1), were therefore subjected to PCA. The first two PCs described 99.37% of the spectral features. The discrimination was achieved by using a loading plot between

  15. First Order Chemical Reaction Effects on Exponentially Accelerated Vertical Plate with Variable Mass Diffusion in the Presence of Thermal Radiation

    Directory of Open Access Journals (Sweden)

    Muthucumaraswamy R.

    2015-05-01

    Full Text Available Effects of transfer of mass and free convection on the flow field of an incompressible viscous fluid past an exponentially accelerated vertical plate with variable surface temperature and mass diffusion are studied. Results for velocity, concentration, temperature are obtained by solving governing equations using the Laplace transform technique. It is observed that the velocity increases with decreasing values of the chemical reaction parameter or radiation parameter. But the trend is just reversed with respect to the time parameter. The skin friction is also studied.

  16. Theoretical analysis of the velocity field, stress field and vortex sheet of generalized second order fluid withfractional anomalous diffusion

    Institute of Scientific and Technical Information of China (English)

    XU; Mingyu(

    2001-01-01

    [1]Nonnemacher, T. F., Metzler, R., On the Riemann-Liouville fractional calculus and some recent applications, Fractals,1995, 3(3): 557-566.[2]Mainardi, F., Fractional calculus: some basic problems in continuum and statistical mechanics, in Fractals and Fractional Calculus in Continuum Mechanics (eds. Cappinteri, A., Mainardi, F.), New York: Springer Wien, 1997, 291-348.[3]Rossikhin, Y. A., Shitikova, M. V. , Applications of fractional calculus to dynamic problems of linear and nonlinear hereditary mechanics of solids, Appl. Mech. Rev., 1997, 50(1): 15-67.[4]Podlubny, I., Fractional Differential Equations, San Diego: Academic Press, 1999, 86-231.[5]Henry, B. I. , Wearne, S. L. , Fractional reaction-diffusion, Physica A, 2000, 276(3): 448-455.[6]Wyss, W., The fractional diffusion equation, J. Math. Phys., 1986, 27(11): 2782-2785.[7]Bagley, R. L. , Torvik, P. J., On the appearance of the fractional derivative in the behavior of real materials, J. Appl.Mech., 1984, 51(2): 294-298.[8]Mathai, A. M., Saxena, R. K., The H-function with Applications in Statistics and Other Disciplines, New Delhi-BangaloreBombay: Wiley Eastern Limited, 1978, 1-12.[9]Gorentlo, R. , Luchko, Y., Mainardi, F., Wright function as scale-invariant solutions of the diffusion-wave equation, J.Comput. Appl. Math., 2000, 118(1): 175-191.[10]Yih, C. S. , Fluid Mechanics: A Concise Introduction to the Theory, New York: MeGraw-Hill, Inc. , 1969, 321-324.[11]Wu Wangyi, Fluid Mechanics (in Chinese), Beijing: Peking Univ. Press, 1983, 226-230.[12]Mainardi, F., Gorenflo, R., On Mittag-Leffler-Type function in fractional evolution processes, J. Comput. Appl. Math.2000, 118(2): 283-299.[13]Anhand, V. V., Leonenko, N. N., Scaling law for fractional diffusion-wave equations with singular data, Statistics and Probability Letters, 2000, 48(3): 239-252.[14]Kivyakova, V., Multiple (multiindex) Mittag-Leffler functions and relations to

  17. A narrow amide I vibrational band observed by sum frequency generation spectroscopy reveals highly ordered structures of a biofilm protein at the air/water interface.

    Science.gov (United States)

    Wang, Zhuguang; Morales-Acosta, M Daniela; Li, Shanghao; Liu, Wei; Kanai, Tapan; Liu, Yuting; Chen, Ya-Na; Walker, Frederick J; Ahn, Charles H; Leblanc, Roger M; Yan, Elsa C Y

    2016-02-18

    We characterized BslA, a bacterial biofilm protein, at the air/water interface using vibrational sum frequency generation spectroscopy and observed one of the sharpest amide I bands ever reported. Combining methods of surface pressure measurements, thin film X-ray reflectivity, and atomic force microscopy, we showed extremely ordered BslA at the interface.

  18. Snapshot imaging spectroscopy of the solar transition region: The Multi-Order Solar EUV Spectrograph (MOSES) sounding rocket mission

    Science.gov (United States)

    Fox, James Lewis

    We have developed a revolutionary spectroscopic technique for solar research in the extreme ultraviolet. This slitless spectrographic technique allows snapshot imaging spectroscopy with data exactly cotemporal and cospectral. I have contributed to the successful realization of an application of this technique in the Multi-Order Solar EUV Spectrograph, MOSES . This instrument launched 2006 Feb 8 as a NASA sounding rocket payload and successfully returned remarkable data of the solar transition region in the He II 304Å spectral line. The unique design of this spectrometer allows the study of transient phenomena in the solar atmosphere, with spatial, spectral, and temporal resolution heretofore unachievable in concert, over a wide field of view. The fundamental concepts behind the MOSES spectrometer are broadly applicable to many solar spectral lines and phenomena and the instrument thus represents a new instrumentation technology. The early fruits of this labor are here reported: the first scientific discovery with the MOSES sounding rocket instrument, our observation of a transition region explosive event, phenomena observed with slit spectrographs since at least 1975, most commonly in lines of C IV (1548Å 1550Å) and Si IV (1393Å, 1402Å). This explosive event is the first seen in He II 304Å. With our novel slitless imaging spectrograph, we are able to see the spatial structure of the event. We observe a bright core expelling two jets that are distinctly non-collinear, in directions that are not anti-parallel, in contradiction to standard models of explosive events, which give collinear jets. The jets have sky-plane velocities of order 75 km s -1 and line-of-sight velocities of +75 km s-1 (blue) and -30 km s-1 (red). The core is a region of high non-thermal doppler broadening, characteristic of explosive events, with maximal broadening 380 km s-1 FWHM. It is possible to resolve the core broadening into red and blue line-of-sight components of maximum doppler

  19. Dopant Diffusion and Activation in Silicon Nanowires Fabricated by ex Situ Doping: A Correlative Study via Atom-Probe Tomography and Scanning Tunneling Spectroscopy.

    Science.gov (United States)

    Sun, Zhiyuan; Hazut, Ori; Huang, Bo-Chao; Chiu, Ya-Ping; Chang, Chia-Seng; Yerushalmi, Roie; Lauhon, Lincoln J; Seidman, David N

    2016-07-13

    Dopants play a critical role in modulating the electric properties of semiconducting materials, ranging from bulk to nanoscale semiconductors, nanowires, and quantum dots. The application of traditional doping methods developed for bulk materials involves additional considerations for nanoscale semiconductors because of the influence of surfaces and stochastic fluctuations, which may become significant at the nanometer-scale level. Monolayer doping is an ex situ doping method that permits the post growth doping of nanowires. Herein, using atom-probe tomography (APT) with subnanometer spatial resolution and atomic-ppm detection limit, we study the distributions of boron and phosphorus in ex situ doped silicon nanowires with accurate control. A highly phosphorus doped outer region and a uniformly boron doped interior are observed, which are not predicted by criteria based on bulk silicon. These phenomena are explained by fast interfacial diffusion of phosphorus and enhanced bulk diffusion of boron, respectively. The APT results are compared with scanning tunneling spectroscopy data, which yields information concerning the electrically active dopants. Overall, comparing the information obtained by the two methods permits us to evaluate the diffusivities of each different dopant type at the nanowire oxide, interface, and core regions. The combined data sets permit us to evaluate the electrical activation and compensation of the dopants in different regions of the nanowires and understand the details that lead to the sharp p-i-n junctions formed across the nanowire for the ex situ doping process.

  20. Investigation on the origin of diffusion impedance in the porous cathode of a proton exchange membrane fuel cell (PEMFC) via electrochemical impedance spectroscopy (EIS)

    Energy Technology Data Exchange (ETDEWEB)

    Mainka, J.; Maranzana, G.; Dillet, J.; Didierjean, S.; Lottin, O. [Nancy Univ., Centre national de la recherche scientifique, Vandoeuvre les Nancy (France). Laboratoire d' Energetique et de Mecanique Theorique et Appliquee

    2009-07-01

    This study provided a preliminary examination of the impact of gas flow rate on the impedance characteristics of a proton exchange membrane fuel cell (PEMFC). The mass transport phenomena within the porous cathode of PEMFCs can be analyzed through electrochemical impedance spectroscopy (EIS). The geometrical description of the electrodes chosen to complete the EIS interpretations is a form of the agglomerate model, where the agglomerates are a mixture of carbon powder and catalyst particles, whereas the electrolyte is assumed to cover only the pore surfaces. Therefore, the reactants access the active catalyst sites by passing successively through the gas diffusion layer (GDL), the pores of the electrode, and finally through a thin electrolyte layer. The fuel cell equivalent electrical circuit is based on a Butler-Volmer formalism that takes into consideration oxygen diffusion in the pores of the GDL and/or the active layer through a Warburg element. The results reveal that in the cathode, the mass transfer limiting layer is most likely the active layer, provided liquid water is present within the pores. Under normal operating conditions, the mass transport resistance of the gas diffusion layer is negligible, as is the fine electrolyte layer coating the agglomerate.

  1. Second-order adjoint sensitivity analysis methodology (2nd-ASAM) for computing exactly and efficiently first- and second-order sensitivities in large-scale linear systems: II. Illustrative application to a paradigm particle diffusion problem

    Science.gov (United States)

    Cacuci, Dan G.

    2015-03-01

    This work presents an illustrative application of the second-order adjoint sensitivity analysis methodology (2nd-ASAM) to a paradigm neutron diffusion problem, which is sufficiently simple to admit an exact solution, thereby making transparent the underlying mathematical derivations. The general theory underlying 2nd-ASAM indicates that, for a physical system comprising Nα parameters, the computation of all of the first- and second-order response sensitivities requires (per response) at most (2Nα + 1) "large-scale" computations using the first-level and, respectively, second-level adjoint sensitivity systems (1st-LASS and 2nd-LASS). Very importantly, however, the illustrative application presented in this work shows that the actual number of adjoint computations needed for computing all of the first- and second-order response sensitivities may be significantly less than (2Nα + 1) per response. For this illustrative problem, four "large-scale" adjoint computations sufficed for the complete and exact computations of all 4 first- and 10 distinct second-order derivatives. Furthermore, the construction and solution of the 2nd-LASS requires very little additional effort beyond the construction of the adjoint sensitivity system needed for computing the first-order sensitivities. Very significantly, only the sources on the right-sides of the diffusion (differential) operator needed to be modified; the left-side of the differential equations (and hence the "solver" in large-scale practical applications) remained unchanged. All of the first-order relative response sensitivities to the model parameters have significantly large values, of order unity. Also importantly, most of the second-order relative sensitivities are just as large, and some even up to twice as large as the first-order sensitivities. In the illustrative example presented in this work, the second-order sensitivities contribute little to the response variances and covariances. However, they have the

  2. Electronic spectroscopies

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    2000-01-01

    Diffuse reflectance spectroscopy (DRS) in the ultraviolet, visible and near-infrared region is a versatile spectroscopic technique, as both d-d and charge transfer transitions of supported TMI can be probed. One of the advantages of electronic spectroscopy is that the obtained information is

  3. Critical assessment of diffusion coefficients in semidilute to concentrated solutions of polystyrene in toluene.

    Science.gov (United States)

    Pollak, T; Köhler, W

    2009-03-28

    We have measured collective diffusion coefficients of dilute, semidilute, and concentrated solutions of polystyrene in toluene up to a polymer concentration of 0.832 mass fractions at T=25 degrees C. The three employed experimental techniques of photon correlation spectroscopy, thermal diffusion forced Rayleigh scattering, and optical beam deflection cover four orders of magnitude with respect to their characteristic diffusion lengths (200 nm-2.9 mm), corresponding to more than 8 decades of the diffusion time constants. Contrary to existing literature data, which suggest a length scale dependent anomalous diffusion at high concentrations, all our techniques yield identical diffusion coefficients and purely Fickian diffusion, irrespective of their characteristic length scale.

  4. Monitoring the diffusion behavior of Na,K-ATPase by fluorescence correlation spectroscopy (FCS) upon fluorescence labelling with eGFP or Dreiklang

    Science.gov (United States)

    Junghans, Cornelia; Schmitt, Franz-Josef; Vukojević, Vladana; Friedrich, Thomas

    2016-02-01

    Measurement of lateral mobility of membraneembedded proteins in living cells with high spatial and temporal precision is a challenging task of optofluidics. Biological membranes are complex structures, whose physico-chemical properties depend on the local lipid composition, cholesterol content and the presence of integral or peripheral membrane proteins, which may be involved in supramolecular complexes or are linked to cellular matrix proteins or the cytoskeleton. The high proteinto- lipid ratios in biomembranes indicate that membrane proteins are particularly subject to molecular crowding, making it difficult to follow the track of individual molecules carrying a fluorescence label. Novel switchable fluorescence proteins such as Dreiklang [1], are, in principle, promising tools to study the diffusion behavior of individual molecules in situations of molecular crowding due to excellent spectral control of the ON- and OFF-switching process. In this work, we expressed an integral membrane transport protein, the Na,K-ATPase comprising the human α2-subunit carrying an N-terminal eGFP or Dreiklang tag and human β1-subunit, in HEK293T cells and measured autocorrelation curves by fluorescence correlation spectroscopy (FCS). Furthermore,we measured diffusion times and diffusion constants of eGFP and Dreiklang by FCS, first, in aqueous solution after purification of the proteins upon expression in E. coli, and, second, upon expression as soluble proteins in the cytoplasm of HEK293T cells. Our data show that the diffusion behavior of the purified eGFP and Dreiklang in solution as well as the properties of the proteins expressed in the cytoplasm are very similar. However, the autocorrelation curves of eGFP- and Dreiklanglabeled Na,K-ATPase measured in the plasma membrane exhibit marked differences, with the Dreiklang-labeled construct showing shorter diffusion times. This may be related to an additional, as yet unrecognized quenching process that occurs on the same time

  5. Single-particle spectroscopy of I-III-VI semiconductor nanocrystals: spectral diffusion and suppression of blinking by two-color excitation

    Science.gov (United States)

    Sharma, Dharmendar Kumar; Hirata, Shuzo; Bujak, Lukasz; Biju, Vasudevanpillai; Kameyama, Tatsuya; Kishi, Marino; Torimoto, Tsukasa; Vacha, Martin

    2016-07-01

    Ternary I-III-VI semiconductor nanocrystals have been explored as non-toxic alternatives to II-VI semiconductors for optoelectronic and sensing applications, but large photoluminescence spectral width and moderate brightness restrict their practical use. Here, using single-particle photoluminescence spectroscopy on nanocrystals of (AgIn)xZn2(1-x)S2 we show that the photoluminescence band is inhomogeneously broadened and that size distribution is the dominant factor in the broadening. The residual homogeneous linewidth of individual nanocrystals reaches up to 75% of the ensemble spectral width. Single nanocrystals undergo spectral diffusion which also contributes to the inhomogeneous band. Excitation with two lasers with energies above and below the bandgap reveals coexistence of two emitting donor states within one particle. Spectral diffusion in such particles is due to temporal activation and deactivation of one such state. Filling of a trap state with a lower-energy laser enables optical modulation of photoluminescence intermittency (blinking) and leads to an almost two-fold increase in brightness.Ternary I-III-VI semiconductor nanocrystals have been explored as non-toxic alternatives to II-VI semiconductors for optoelectronic and sensing applications, but large photoluminescence spectral width and moderate brightness restrict their practical use. Here, using single-particle photoluminescence spectroscopy on nanocrystals of (AgIn)xZn2(1-x)S2 we show that the photoluminescence band is inhomogeneously broadened and that size distribution is the dominant factor in the broadening. The residual homogeneous linewidth of individual nanocrystals reaches up to 75% of the ensemble spectral width. Single nanocrystals undergo spectral diffusion which also contributes to the inhomogeneous band. Excitation with two lasers with energies above and below the bandgap reveals coexistence of two emitting donor states within one particle. Spectral diffusion in such particles is due

  6. Third-order non-linear optical susceptibilities in diffusion modified AlxGa1-xN/GaN single quantum well

    Science.gov (United States)

    Das, T.; Panda, M.; Panda, S.; Panda, B. K.

    2017-05-01

    In this work, the variation of optical properties in the AlGaN/GaN quantum well after thermal annealing is studied. The potential profile change of the quantum well resulting from the interdiffusion of Ga and Al atoms across the interface of the well and the barrier during the thermal treatments is assumed to follow Fick's law. The results show that the thermal annealing can induce an increase of the optical susceptibilities in the AlGaN/GaN quantum well. However the third-order nonlinear optical susceptibilities are red shifted with increasing in diffusion lengths.

  7. Empirical likelihood based inference for second-order diffusion models%二阶扩散模型的经验似然推断

    Institute of Scientific and Technical Information of China (English)

    王允艳; 张立新; 王汉超

    2012-01-01

    In this paper, we develop an empirical likelihood method to construct empirical likelihood estimators for nonparametric drift and diffusion functions in the second-order diffusion model, and the consistency and asymptotic normality of the empirical likelihood estimators are obtained. Moreover, the nonsymmetric confidence intervals for drift and diffusion functions based on empirical likelihood methods are obtained, and the adjusted empirical log-likelihood ratio is proved to be asymptotically standard chi-square under some mild conditions.%本文利用经验似然方法得到了二阶扩散模型的漂移系数和扩散系数的经验似然估计量,并研究这些估计量的相合性和渐近正态性.进一步在经验似然方法的基础上给出了漂移系数和扩散系数的非对称的置信区间,并且在一定的条件下证明了调整的对数似然比是渐近卡方分布的.

  8. Molecular order at polymer interfaces measured by broad-bandwidth vibrationally-resolved sum frequency generation spectroscopy.

    Science.gov (United States)

    Wilson, Philip T.; Briggman, Kimberly A.; Stephenson, John C.; Wallace, William E.; Richter, Lee J.

    2001-03-01

    Broad-bandwidth vibrationally-resolved sum frequency generation (VR-SFG)spectroscopy has been used to measure the molecular orientation distribution at polymer/dielectric interfaces. A novel three layer microcavity structure of polystyrene (i.e.,PS)/spin-on hydrogen silsesquioxane dielectric (i.e.,spin-on glass)/Au has been developed in which manipulation of Fresnel factors through the variation of dielectric thickness allows unique spectroscopic study of either the free or buried polymer interface. Chemically specific VR-SFG spectroscopy of the phenyl groups of PS reveals opposite absolute orientations of these groups for the two interfaces, each directed away from the bulk of the PS film.

  9. Multidimensional diffusion MRI

    Science.gov (United States)

    Topgaard, Daniel

    2017-02-01

    Principles from multidimensional NMR spectroscopy, and in particular solid-state NMR, have recently been transferred to the field of diffusion MRI, offering non-invasive characterization of heterogeneous anisotropic materials, such as the human brain, at an unprecedented level of detail. Here we revisit the basic physics of solid-state NMR and diffusion MRI to pinpoint the origin of the somewhat unexpected analogy between the two fields, and provide an overview of current diffusion MRI acquisition protocols and data analysis methods to quantify the composition of heterogeneous materials in terms of diffusion tensor distributions with size, shape, and orientation dimensions. While the most advanced methods allow estimation of the complete multidimensional distributions, simpler methods focus on various projections onto lower-dimensional spaces as well as determination of means and variances rather than actual distributions. Even the less advanced methods provide simple and intuitive scalar parameters that are directly related to microstructural features that can be observed in optical microscopy images, e.g. average cell eccentricity, variance of cell density, and orientational order - properties that are inextricably entangled in conventional diffusion MRI. Key to disentangling all these microstructural features is MRI signal acquisition combining isotropic and directional dimensions, just as in the field of multidimensional solid-state NMR from which most of the ideas for the new methods are derived.

  10. In situ diffuse reflectance infrared Fourier transform spectroscopy study of formaldehyde adsorption and reactions on nano γ-Fe2O3 films

    Science.gov (United States)

    Huang, Kaijin; Kong, Lingcong; Yuan, Fangli; Xie, Changsheng

    2013-04-01

    The nano γ-Fe2O3 films gas sensor was fabricated by the screen printing technology. The phase structures and morphologies of nano γ-Fe2O3 films were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), respectively. The gas sensitivity of the films to 100 ppm formaldehyde was investigated. The surface adsorption and reaction process between nano γ-Fe2O3 films and formaldehyde was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) method at different temperatures. DRIFTS results showed that dioxymethylene, formate ions, polyoxymethylene and molecularly formaldehyde surface species were detected when the nano γ-Fe2O3 films exposed to 100 ppm formaldehyde at different temperatures. A possible mechanism of the reaction process was discussed.

  11. In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) study of formaldehyde adsorption and reactions on Pd-doped nano-γ-Fe₂O₃ films.

    Science.gov (United States)

    Huang, Kaijin; Kong, Lingcong; Yuan, Fangli; Xie, Changsheng

    2013-08-01

    Palladium-doped nano-γ-Fe₂O₃ films were printed on Al₂O₃ substrates by screen printing-injecting hybrid technology. X-ray diffraction and scanning electron microscopy techniques were used to characterize the phase structures and morphologies of the films, respectively. The sensitivity of the films to 100 ppm formaldehyde in air was investigated. The surface adsorption and reaction process between Pd-doped nano-γ-Fe₂O₃ films and formaldehyde was studied by in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) at different temperatures. Dioxymethylene, formate ions, polyoxymethylene, and adsorbed formaldehyde were detected when the Pd-doped nano-γ-Fe₂O₃ films were exposed to 100 ppm formaldehyde at different temperatures. A possible mechanism of the reaction process is discussed.

  12. Time-resolved diffuse optical spectroscopy up to 1700 nm using a time-gated InGaAs/InP single-photon avalanche diode

    Science.gov (United States)

    Bargigia, I.; Tosi, A.; Bahgat Shehata, A.; Della Frera, A.; Farina, A.; Bassi, A.; Taroni, P.; Dalla Mora, A.; Zappa, F.; Pifferi, A.

    2011-07-01

    Time-domain diffuse optical spectroscopy has become a powerful tool to study highly scattering media, mainly in the fields of non-invasive medical diagnostics and quality assessment of food and pharmaceutical products. Up to now this technique has been exploited mostly up to 1100 nm: we extend the spectral range by means of a continuously tunable pulsed laser source at a high repetition rate and a custom InGaAs/InP Single-Photon Avalanche Diode operated in time-gated mode, working up to 1700 nm. The characterization of the system is presented. As a first example of application, we measured the absorption spectrum of collagen powder in the range 1100 - 1700 nm, which could prove useful for breast density assessment.

  13. Electrochemical impedance spectroscopy study of a surface confined redox reaction: The reduction of azobenzene on mercury in the absence of diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Francisco, E-mail: dapena@us.es [Department of Physical Chemistry, University of Seville, c/Profesor Garcia Gonzalez no 2, 41012 Seville (Spain); Rueda, Manuela; Hidalgo, Jose; Martinez, Elisa; Navarro, Inmaculada [Department of Physical Chemistry, University of Seville, c/Profesor Garcia Gonzalez no 2, 41012 Seville (Spain)

    2011-09-30

    The kinetics of azobenzene reduction on mercury electrodes in the absence of diffussional mass transport is studied by electrochemical impedance spectroscopy (EIS) in acetic acid/acetate buffered solutions at different pH values. Cyclic voltammetry experiments confirm the absence of diffusion effects and provide the values of the surface equilibrium potential. The analysis of the impedance frequency spectrums at every potential within the faradaic region conforms well the model and provides the global rate constant of the process, k{sub f}. The potential dependence of k{sub f} suggests the existence of an EE mechanism, with two electron transfers controlling the overall rate. The kinetic parameters of every step are obtained and their pH dependences clarify the role played by the protonation steps.

  14. Noninvasive evaluation of collagen and hemoglobin contents and scattering property of in vivo keloid scars and normal skin using diffuse reflectance spectroscopy: pilot study

    Science.gov (United States)

    Tseng, Sheng-Hao; Hsu, Chao-Kai; Yu-Yun Lee, Julia; Tzeng, Shih-Yu; Chen, Wan-Rung; Liaw, Yu-Kai

    2012-07-01

    Collagen is a rich component in skin that provides skin structure integrity; however, its contribution to the absorption and scattering properties of various types of skin has not been extensively studied. We considered the contribution of the collagen to the absorption spectrum of in vivo normal skin and keloids of 12 subjects derived from our diffuse reflectance spectroscopy (DRS) system in the wavelength range from 550 to 860 nm. It was found that the collagen concentration, the hemoglobin oxygen saturation, and the reduced scattering coefficient of keloids were remarkably different from that of normal skin. Our results suggest that our DRS system could assist clinicians in understanding the functional and structural condition of keloid scars. In the future, we will evaluate the accuracy of our system in the keloid diagnosis and investigate the applicability of our system for other skin-collagen-related studies.

  15. Comparison of conventional and diffusion-weighted MRI and proton MR spectroscopy in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like events

    Energy Technology Data Exchange (ETDEWEB)

    Abe, K.; Hikita, T.; Sakoda, S. [Department of Neurology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, 565-0871, Osaka (Japan); Yoshimura, H.; Tanaka, H.; Fujita, N. [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, 565-0871, Osaka (Japan)

    2004-02-01

    The mechanism of neurological disturbances in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is controversial. We studied 12 patients with MELAS using conventional and diffusion weighted MRI (DWI) and MR spectroscopy (MRS), to look at the physiopathology of the stroke-like events. Although conventional MRI showed lesions in all patients, DWI was more sensitive. One patient did not show high signal on DWI 48 h after a from stroke-like episode, but MRS demonstrated a lactate peak in left occipital lobe; 2 weeks after the attack, high signal was demonstrated on the right frontal lobe where MRS had shown a lactate peak. Our findings suggest a possible predictive ability of {sup 1}H-MRS, in showing early MELAS lesions and supports the hypothesis that mitochondrial metabolic dysfunction may precedes abnormalities on DWI. (orig.)

  16. Gas sensing properties and in situ diffuse reflectance infrared Fourier transform spectroscopy study of trichloroethylene adsorption and reactions on SnO2 films

    Science.gov (United States)

    Zhang, Zhenxin; Huang, Kaijin; Yuan, Fangli; Xie, Changsheng

    2014-05-01

    The detection of trichloroethylene has attracted much attention because it has an important effect on human health. The sensitivity of the SnO2 flat-type coplanar gas sensor arrays to 100 ppm trichloroethylene in air was investigated. The adsorption and surface reactions of trichloroethylene were investigated at 100-200 °C by in-situ diffuse reflection Fourier transform infrared spectroscopy (DIRFTS) on SnO2 films. Molecularly adsorbed trichloroethylene, dichloroacetyl chloride (DCAC), phosgene, HCl, CO, H2O, CHCl3, Cl2 and CO2 surface species are formed during trichloroethylene adsorption at 100-200 °C. A possible mechanism of the reaction process is discussed.

  17. Sol-gel hosts doped with porphyrin derivatives. Part I. Spectroscopy, hole-burning and spectral diffusion

    Science.gov (United States)

    Kulikov, S. G.; Veret-Lemarinier, A. V.; Galaup, J. P.; Chaput, F.; Boilot, J. P.

    1997-03-01

    Pure inorganic sol-gel matrices as well as hybrid organic/inorganic xerogels have been doped with porphyrins derivatives and studied using line narrowing techniques. The role of residual hydroxyl groups is investigated. Free-base porphyrins are protonated in pure inorganic hosts, but the matrix acidity is reduced in hybrid matrices or when fluorinated porphyrins derivatives are used. The linear electron-phonon coupling can be controlled with the choice of the organic group in organic/inorganic matrices. Persistent spectral hole widths increase with temperature according a glass-like Tn dependence and evidence of spectral diffusion is shown in one of these systems.

  18. Variational Multiscale Stabilization and p-adaptivity of High-Order Spectral Elements for the Convection-Diffusion Equation (Preprint)

    Science.gov (United States)

    2011-07-26

    Cottrell, and Bazilevs in [21], where NURBS were used as high-order basis functions, un- expected convergence to monotone results were obtained...methods by Canuto and coworkers in [17, 18, 19, 52], and later by Hughes and coworkers in [21] using non-uniform rational B-splines ( NURBS ). In this...Hughes, J. A. Cottrell, Y. Bazilevs, Isogeometric analysis: CAD, finite elements, NURBS , exact geometry and mesh refinement, Comput. Methods Appl

  19. An investigation of the coordination number of Ni 2+ in nickel bearing phyllosilicates using diffuse reflectance spectroscopy

    Science.gov (United States)

    Tejedor-Tejedor, M. Isabel; Anderson, Marc A.; Herbillon, Adrien J.

    1983-11-01

    Visible region reflectance spectroscopy and nonlinear regression analysis of spectral data have been used to present qualitative and semiquantitative evidence that some tetrahedral Ni 2+ is present in all six phyllosilicates examined. Highly crystalline willemseite and chrysotile, poorly crystalline nepouite as well as two natural minerals, and a mixture of poorly crystalline nepouite and nickel hydroxide all showed the presence of tetrahedral Ni 2+ as well as octahedral nickel. Chemical analysis of willemseite confirmed quantitatively the presence of excess Ni lending further support for the presence of tetrahedral nickel.

  20. Early detection of secondary damage in ipsilateral thalamus after acute infarction at unilateral corona radiata by diffusion tensor imaging and magnetic resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Pei Zhong

    2011-05-01

    Full Text Available Abstract Background Traditional magnetic resonance (MR imaging can identify abnormal changes in ipsilateral thalamus in patients with unilateral middle cerebral artery (MCA infarcts. However, it is difficult to demonstrate these early changes quantitatively. Diffusion tensor imaging (DTI and proton magnetic resonance spectroscopy (MRS are potentially sensitive and quantitative methods of detection in examining changes of tissue microstructure and metabolism. In this study, We used both DTI and MRS to examine possible secondary damage of thalamus in patients with corona radiata infarction. Methods Twelve patients with unilateral corona radiata infarction underwent MR imaging including DTI and MRS at one week (W1, four weeks (W4, and twelve weeks (W12 after onset of stroke. Twelve age-matched controls were imaged. Mean diffusivity (MD, fractional anisotropy (FA, N-acetylaspartate (NAA, choline(Cho, and creatine(Cr were measured in thalami. Results T1-weighted fluid attenuation inversion recovery (FLAIR, T2-weighted, and T2-FLAIR imaging showed an infarct at unilateral corona radiate but no other lesion in each patient brain. In patients, MD was significantly increased at W12, compared to W1 and W4 (all PP Conclusions These findings indicate that DTI and MRS can detect the early changes indicating secondary damage in the ipsilateral thalamus after unilateral corona radiata infarction. MRS may reveal the progressive course of damage in the ipsilateral thalamus over time.

  1. A novel combined approach of diffuse reflectance UV-Vis-NIR spectroscopy and multivariate analysis for non-destructive examination of blue ballpoint pen inks in forensic application.

    Science.gov (United States)

    Kumar, Raj; Sharma, Vishal

    2017-03-15

    The present research is focused on the analysis of writing inks using destructive UV-Vis spectroscopy (dissolution of ink by the solvent) and non-destructive diffuse reflectance UV-Vis-NIR spectroscopy along with Chemometrics. Fifty seven samples of blue ballpoint pen inks were analyzed under optimum conditions to determine the differences in spectral features of inks among same and different manufacturers. Normalization was performed on the spectroscopic data before chemometric analysis. Principal Component Analysis (PCA) and K-mean cluster analysis were used on the data to ascertain whether the blue ballpoint pen inks could be differentiated by their UV-Vis/UV-Vis NIR spectra. The discriminating power is calculated by qualitative analysis by the visual comparison of the spectra (absorbance peaks), produced by the destructive and non-destructive methods. In the latter two methods, the pairwise comparison is made by incorporating the clustering method. It is found that chemometric method provides better discriminating power (98.72% and 99.46%, in destructive and non-destructive, respectively) in comparison to the qualitative analysis (69.67%). Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Innovative analytical methodology combining micro-x-ray diffraction, scanning electron microscopy-based mineral maps, and diffuse reflectance infrared fourier transform spectroscopy to characterize archeological artifacts.

    Science.gov (United States)

    Cardell, Carolina; Guerra, Isabel; Romero-Pastor, Julia; Cultrone, Giuseppe; Rodriguez-Navarro, Alejandro

    2009-01-15

    Excavations at the 14th century Moorish rampart (Granada, Spain) unearthed a brick oven alongside black ash and bone stratigraphic layers. In situ evidence suggests the oven served to fabricate a wall coating including powdered burnt bones. Original ad hoc analyses improved on conventional methods were used to confirm this hypothesis. These methods enable (i) nondestructive micro-X-ray diffraction (mu-XRD) for fast mineralogical data acquisition (approximately 10 s) and moderately high spatial (approximately 500 microm) resolution and (ii) identification and imaging of crystalline components in sample cross-sections via mineral maps, yielding outstanding visualization of grain distribution and morphology in composite samples based on scanning electron microscopy-energy dispersion X-ray spectrometry (SEM-EDX) elemental maps. Benefits are shown for applying diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) vs transmittance-FT-IR (T-FT-IR) to analyze organic and inorganic components in single samples. Complementary techniques to fully characterize artifacts were gas chromatography/mass spectroscopy (GC/MS), optical microscopy (OM), conventional powder XRD, and (14)C dating. Bone-hydroxyapatite was detected in the coating. Mineralogical transformations in the bricks indicate oven temperatures well above 1000 degrees C, supporting the hypothesis.

  3. A novel combined approach of diffuse reflectance UV-Vis-NIR spectroscopy and multivariate analysis for non-destructive examination of blue ballpoint pen inks in forensic application

    Science.gov (United States)

    Kumar, Raj; Sharma, Vishal

    2017-03-01

    The present research is focused on the analysis of writing inks using destructive UV-Vis spectroscopy (dissolution of ink by the solvent) and non-destructive diffuse reflectance UV-Vis-NIR spectroscopy along with Chemometrics. Fifty seven samples of blue ballpoint pen inks were analyzed under optimum conditions to determine the differences in spectral features of inks among same and different manufacturers. Normalization was performed on the spectroscopic data before chemometric analysis. Principal Component Analysis (PCA) and K-mean cluster analysis were used on the data to ascertain whether the blue ballpoint pen inks could be differentiated by their UV-Vis/UV-Vis NIR spectra. The discriminating power is calculated by qualitative analysis by the visual comparison of the spectra (absorbance peaks), produced by the destructive and non-destructive methods. In the latter two methods, the pairwise comparison is made by incorporating the clustering method. It is found that chemometric method provides better discriminating power (98.72% and 99.46%, in destructive and non-destructive, respectively) in comparison to the qualitative analysis (69.67%).

  4. An approach by using near-infrared diffuse reflectance spectroscopy and resin adsorption for the determination of copper, cobalt and nickel ions in dilute solution.

    Science.gov (United States)

    Sheng, Nan; Cai, Wensheng; Shao, Xueguang

    2009-07-15

    Near-infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool and used in various fields, it is seldom, however, used in the analysis of metal ions in solutions. A method for quantitative determination of metal ions in solution is developed by using resin adsorption and near-infrared diffuse reflectance spectroscopy (NIRDRS). The method makes use of the resin adsorption for gathering the analytes from a dilute solution, and then NIRDRS of the adsorbate is measured. Because both the information of the metal ions and their interaction with the functional group of resin can be reflected in the spectrum, quantitative determination is achieved by using multivariate calibration technique. Taking copper (Cu(2+)), cobalt (Co(2+)) and nickel (Ni(2+)) as the analyzing targets and D401 resin as the adsorbent, partial least squares (PLS) model is built from the NIRDRS of the adsorbates. The results show that the concentrations that can be quantitatively detected are as low as 1.00, 1.98 and 1.00 mg L(-1) for Cu(2+), Co(2+) and Ni(2+), respectively, and the coexistent ions do not influence the determination.

  5. The application of diffuse reflectance infrared spectroscopy and temperature-programmed desorption to investigate the interaction of methanol on eta-alumina.

    Science.gov (United States)

    McInroy, Alastair R; Lundie, David T; Winfield, John M; Dudman, Chris C; Jones, Peter; Lennon, David

    2005-11-22

    The adsorption of methanol and its subsequent transformation to form dimethyl ether (DME) on a commercial grade eta-alumina catalyst has been investigated using a combination of mass selective temperature-programmed desorption (TPD) and diffuse reflectance infrared spectroscopy (DRIFTS). The infrared spectrum of a saturated overlayer of methanol on eta-alumina shows the surface to be comprised of associatively adsorbed methanol and chemisorbed methoxy species. TPD shows methanol and DME to desorb with respective maxima at 380 and 480 K, with desorption detectable for both molecules up to ca. 700 K. At 673 K, infrared spectroscopy reveals the formation of a formate species; the spectral line width of the antisymmetric C-O stretch indicates the adoption of a high symmetry adsorbed state. Conventional TPD using a tubular reactor, combined with mass spectrometric analysis of the gas stream exiting the IR cell, indicate hydrogen and methane evolution to be associated with formation of the surface formate group and CO evolution with its decomposition. A reaction scheme is proposed for the generation and decomposition of this important reaction intermediate. The overall processes involved in (i) the adsorption/desorption of methanol, (ii) the transformation of methanol to DME, and (iii) the formation and decomposition of formate species are discussed within the context of a recently developed four-site model for the Lewis acidity of eta-alumina.

  6. Electrochemical determination of the diffusion coefficient of cations into Chevrel phase-based electrochemical transfer junction by potential step chronoamperometry and impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Seghir, S.; Stein, N. [Institut Jean Lamour - Electrochimie des Materiaux, Nancy-Universite, Universite Paul Verlaine Metz, CNRS, 1 Bd. Arago, F-57078 Metz (France); Boulanger, C., E-mail: clotilde.boulanger@univ-metz.f [Institut Jean Lamour - Electrochimie des Materiaux, Nancy-Universite, Universite Paul Verlaine Metz, CNRS, 1 Bd. Arago, F-57078 Metz (France); Lecuire, J.-M. [Institut Jean Lamour - Electrochimie des Materiaux, Nancy-Universite, Universite Paul Verlaine Metz, CNRS, 1 Bd. Arago, F-57078 Metz (France)

    2011-02-15

    The molybdenum chalcogenides Mo{sub 6}X{sub 8} (X = S, Se) offer the possibility of intercalation/de-intercalation processes by chemical or electrochemical way. Besides the different applications of so-called Chevrel phases, we have proposed an electrochemical transfer junction for selective recovery of metallic cations in the perspective of recycling of industrial liquid mineral wastes. Thus, the knowledge of the diffusion properties of cations in the Chevrel phases is essential. Here we report on the electrochemical determination of diffusion coefficients of Co{sup 2+}, Ni{sup 2+}, Fe{sup 2+}, Cd{sup 2+}, Zn{sup 2+}, Mn{sup 2+} and Cu{sup 2+} for Mo{sub 6}S{sub 8} and Mo{sub 6}Se{sub 8} matrices. Experiments were realized on samples with compactness of 50% and 96-98%. They point out that the lower compactness is unfavorable to the mobility of the cobalt ions. From potential step chronoamperometry and electrochemical impedance spectroscopy, the diffusion coefficients were found around 10{sup -9} cm{sup 2} s{sup -1}, even 10{sup -6} cm{sup 2} s{sup -1} for copper. These results confirm the high mobility of transition metal ions in studied phases and complete the data for Co, Fe or Mn-Mo{sub 6}S{sub 8} system and Mn-Mo{sub 6}Se{sub 8} system. For the sulfide phase, the following sequence for D-tilde is observed Ni < Co < Fe < Cd < Zn < Mn << Cu and can be explained in regards with structural considerations and repulsion effects for copper.

  7. Development and Validation of a Three-Dimensional Diffusion Code Based on a High Order Nodal Expansion Method for Hexagonal-z Geometry

    Directory of Open Access Journals (Sweden)

    Daogang Lu

    2016-01-01

    Full Text Available A three-dimensional, multigroup, diffusion code based on a high order nodal expansion method for hexagonal-z geometry (HNHEX was developed to perform the neutronic analysis of hexagonal-z geometry. In this method, one-dimensional radial and axial spatially flux of each node and energy group are defined as quadratic polynomial expansion and four-order polynomial expansion, respectively. The approximations for one-dimensional radial and axial spatially flux both have second-order accuracy. Moment weighting is used to obtain high order expansion coefficients of the polynomials of one-dimensional radial and axial spatially flux. The partially integrated radial and axial leakages are both approximated by the quadratic polynomial. The coarse-mesh rebalance method with the asymptotic source extrapolation is applied to accelerate the calculation. This code is used for calculation of effective multiplication factor, neutron flux distribution, and power distribution. The numerical calculation in this paper for three-dimensional SNR and VVER 440 benchmark problems demonstrates the accuracy of the code. In addition, the results show that the accuracy of the code is improved by applying quadratic approximation for partially integrated axial leakage and four-order approximation for one-dimensional axial spatially flux in comparison to flat approximation for partially integrated axial leakage and quadratic approximation for one-dimensional axial spatially flux.

  8. Combined zero-quantum and spin-diffusion mixing for efficient homonuclear correlation spectroscopy under fast MAS: broadband recoupling and detection of long-range correlations.

    Science.gov (United States)

    Lu, Xingyu; Guo, Changmiao; Hou, Guangjin; Polenova, Tatyana

    2015-01-01

    Fast magic angle spinning (MAS) NMR spectroscopy is emerging as an essential analytical and structural biology technique. Large resolution and sensitivity enhancements observed under fast MAS conditions enable structural and dynamics analysis of challenging systems, such as large macromolecular assemblies and isotopically dilute samples, using only a fraction of material required for conventional experiments. Homonuclear dipolar-based correlation spectroscopy constitutes a centerpiece in the MAS NMR methodological toolbox, and is used essentially in every biological and organic system for deriving resonance assignments and distance restraints information necessary for structural analysis. Under fast MAS conditions (rotation frequencies above 35-40 kHz), dipolar-based techniques that yield multi-bond correlations and non-trivial distance information are ineffective and suffer from low polarization transfer efficiency. To overcome this limitation, we have developed a family of experiments, CORD-RFDR. These experiments exploit the advantages of both zero-quantum RFDR and spin-diffusion based CORD methods, and exhibit highly efficient and broadband dipolar recoupling across the entire spectrum, for both short-range and long-range correlations. We have verified the performance of the CORD-RFDR sequences experimentally on a U-(13)C,(15)N-MLF tripeptide and by numerical simulations. We demonstrate applications of 2D CORD-RFDR correlation spectroscopy in dynein light chain LC8 and HIV-1 CA tubular assemblies. In the CORD-RFDR spectra of LC8 acquired at the MAS frequency of 40 kHz, many new intra- and inter-residue correlations are detected, which were not observed with conventional dipolar recoupling sequences. At a moderate MAS frequency of 14 kHz, the CORD-RFDR experiment exhibits excellent performance as well, as demonstrated in the HIV-1 CA tubular assemblies. Taken together, the results indicate that CORD-RFDR experiment is beneficial in a broad range of conditions

  9. Rapid strain classification and taxa delimitation within the edible mushroom genus Pleurotus through the use of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy.

    Science.gov (United States)

    Zervakis, Georgios I; Bekiaris, Georgios; Tarantilis, Petros Α; Pappas, Christos S

    2012-06-01

    Fourier transform infrared (FT-IR) spectroscopy has been successfully applied for the identification of bacteria and yeasts, but only to a limited extent for discriminating specific groups of filamentous fungi. In the frame of this study, 73 strains - from different associated hosts/substrates and geographic regions - representing 16 taxa of the edible mushroom genus Pleurotus (Basidiomycota, Agaricales) were examined through the use of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. A binary matrix, elaborated on the basis of presence/absence of specific absorbance peaks combined with cluster analysis, demonstrated that the spectral region 1800-600 cm(-1) permitted clear delimitation of individual strains into Pleurotus species. In addition, closely related species (e.g., Pleurotus ostreatus and Pleurotus pulmonarius) or taxa of the subgenus Coremiopleurotus demonstrated high similarity in their absorbance patterns, whereas genetically distinct entities such as Pleurotus dryinus, Pleurotus djamor, and Pleurotus eryngii provided spectra with noteworthy differences. When specific regions (1800-1700, 1360-1285, 1125-1068, and 950-650 cm(-1)) were evaluated in respect to the absorbance values demonstrated by individual strains, it was evidenced that this methodology could be eventually exploited for the identification of unknown Pleurotus specimens with a stepwise process and with the aid of a dichotomous key developed for this purpose. Moreover, it was shown that the nature of original fungal material examined (mycelium, basidiomata, and basidiospores) had an effect on the outcome of such analyses, and so did the use of different mycelium growth substrates. In conclusion, application of FT-IR spectroscopy provided a fast, reliable, and cost-efficient solution for the classification of pure cultures from closely related mushroom species.

  10. High-order harmonic generation in Xe, Kr, and Ar driven by a 2.1-\\mu m source: high-order harmonic spectroscopy under macroscopic effects

    CERN Document Server

    Hong, Kyung-Han; Gkortsas, Vasileios-Marios; Huang, Shu-Wei; Moses, Jeffrey; Granados, Eduardo; Bhardwaj, Siddharth; Kärtner, Franz X

    2012-01-01

    We experimentally and numerically study the atomic response and pulse propagation effects of high-order harmonics generated in Xe, Kr, and Ar driven by a 2.1-\\mu m infrared femtosecond light source. The light source is an optical parametric chirped-pulse amplifier, and a modified strong-field approximation and 3-dimensional pulse propagation code are used for the numerical simulations. The extended cutoff in the long-wavelength driven high-harmonic generation has revealed the spectral shaping of high-order harmonics due to the atomic structure (or photo-recombination cross-section) and the macroscopic effects, which are the main factors of determining the conversion efficiency besides the driving wavelength. Using precise numerical simulations to determine the macroscopic electron wavepacket, we are able to extract the photo-recombination cross-sections from experimental high-order harmonic spectra in the presence of macroscopic effects. We have experimentally observed that the macroscopic effects shift the o...

  11. Adding diffuse reflectance infrared Fourier transform spectroscopy capability to extended x-ray-absorption fine structure in a new cell to study solid catalysts in combination with a modulation approach

    Energy Technology Data Exchange (ETDEWEB)

    Chiarello, Gian Luca [Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, I-20133 Milano, Italy and Empa, Swiss Federal Laboratories for Materials Science and Technology, Lab. for Solid State Chemistry and Catalysis, Ueberlandstrasse 129, CH-8600 Dübendorf (Switzerland); Nachtegaal, Maarten; Marchionni, Valentina; Quaroni, Luca; Ferri, Davide, E-mail: davide.ferri@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2014-07-15

    We describe a novel cell used to combine in situ transmission X-ray absorption spectroscopy (XAS) with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in a single experiment. The novelty of the cell design compared to current examples is that both radiations are passed through an X-ray and IR transparent window in direct contact with the sample. This innovative geometry also offers a wide surface for IR collection. In order to avoid interference from the crystalline IR transparent materials (e.g., CaF{sub 2}, MgF{sub 2}, diamond) a 500 μm carbon filled hole is laser drilled in the center of a CaF{sub 2} window. The cell is designed to represent a plug flow reactor, has reduced dead volume in order to allow for fast exchange of gases and is therefore suitable for experiments under fast transients, e.g., according to the concentration modulation approach. High quality time-resolved XAS and DRIFTS data of a 2 wt.% Pt/Al{sub 2}O{sub 3} catalyst are obtained in concentration modulation experiments where CO (or H{sub 2}) pulses are alternated to O{sub 2} pulses at 150 °C. We show that additional information can be obtained on the Pt redox dynamic under working conditions thanks to the improved sensitivity given by the modulation approach followed by Phase Sensitive Detection (PSD) analysis. It is anticipated that the design of the novel cell is likely suitable for a number of other in situ spectroscopic and diffraction methods.

  12. Quantitative spot-test analysis of metformin in pharmaceutical preparations using ultraviolet-visible diffuse reflectance spectroscopy.

    Science.gov (United States)

    Tubino, Matthieu; Bianchessi, Luís Francisco; Vila, Marta M D C

    2010-01-01

    A quantitative spot-test for the determination of metformin in pharmaceutical preparations using diffuse UV-visible reflectance is reported. The procedure is quite simple, involving in the formation of a metformin-nickel(II) complex on a glass filter membrane with a later measurement of the reflectance in the spectrophotometer using an integration sphere. The analytical results obtained with commercial products were statistically compared with those resulting from a method recommended by JP and by USP, where complete agreement was observed. The average RSD is 2.5% and the detection (0.009 mol L(-1)) and the quantitation (0.03 mol L(-1)) limits are quite adequate for pharmaceutical analysis.

  13. Speciation and Lability of Ag-, AgCl- and Ag2S-Nanoparticles in Soil Determined by X-ray Absorption Spectroscopy and Diffusive Gradients in Thin Films

    Science.gov (United States)

    Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-) and silver sulfide nanoparticles (Ag2S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed "nano" Diffusive Gradients in Thin Films (DGT) devices. These nano-D...

  14. Speciation and Lability of Ag-, AgCl- and Ag2S-Nanoparticles in Soil Determined by X-ray Absorption Spectroscopy and Diffusive Gradients in Thin Films

    Science.gov (United States)

    Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-) and silver sulfide nanoparticles (Ag2S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed "nano" Diffusive Gradients in Thin Films (DGT) devices. These nano-D...

  15. In situ UV–Vis diffuse reflectance spectroscopy — on line activity measurements of supported chromium oxide catalysts: relating isobutane dehydrogenation activity with Cr-speciation via experimental design

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Verberckmoes, A.A.; Debaere, J.; Ooms, K.; Langhans, I.; Schoonheydt, R.A.

    2000-01-01

    The dehydrogenation of isobutane over supported chromium oxide catalysts was studied by a combination of in situ UV–Vis diffuse reflectance spectroscopy and on line GC analysis. A well-defined set of experiments, based on an experimental design, was carried out to develop mathematical models, which

  16. Sensitive determination of trace mercury by UV-visible diffuse reflectance spectroscopy after complexation and membrane filtration-enrichment.

    Science.gov (United States)

    Yin, Changhai; Iqbal, Jibran; Hu, Huilian; Liu, Bingxiang; Zhang, Lei; Zhu, Bilin; Du, Yiping

    2012-09-30

    A simple, sensitive and selective solid phase reflectometry method is proposed for the determination of trace mercury in aqueous samples. The complexation reagent dithizone was firstly injected into the properly buffered solution with vigorous stirring, which started a simultaneous formation of nanoparticles suspension of dithizone and its complexation reaction with the mercury(II) ions to make Hg-dithizone nanoparticles. After a definite time, the mixture was filtered with membrane, and then quantified directly on the surface of the membrane by using integrating sphere accessory of the UV-visible spectrophotometer. The quantitative analysis was carried out at a wavelength of 485 nm since it yielded the largest difference in diffuse reflectance spectra before and after reaction with mercury(II).A good linear correlation in the range of 0.2-4.0 μg/L with a squared correlation coefficient (R(2)) of 0.9944 and a detection limit of 0.12 μg/L were obtained. The accuracy of the method was evaluated by the analysis of spiked mercury(II) concentrations determined using this method along with those determined by the atomic fluorescence mercury vapourmeter and the results obtained were in good agreement. The proposed method was applied to the determination of mercury in tap water and river water samples with the recovery in an acceptable range (95.7-105.3%). Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Sugar-influenced water diffusion, interaction, and retention in clay interlayer nanopores probed by theoretical simulations and experimental spectroscopies

    Science.gov (United States)

    Aristilde, Ludmilla; Galdi, Stephen M.; Kelch, Sabrina E.; Aoki, Thalia G.

    2017-08-01

    Understanding the hydrodynamics in clay nanopores is important for gaining insights into the trapping of water, nutrients, and contaminants in natural and engineered soils. Previous investigations have focused on the interlayer organization and molecular diffusion coefficients (D) of cations and water molecules in cation-saturated interlayer nanopores of smectite clays. Little is known, however, about how these interlayer dynamic properties are influenced by the ubiquitous presence of small organic compounds such as sugars in the soil environment. Here we probed the effects of glucose molecules on montmorillonite interlayer properties. Molecular dynamics simulations revealed re-structuring of the interlayer organization of the adsorptive species. Water-water interactions were disrupted by glucose-water H-bonding interactions. ;Dehydration; of the glucose-populated nanopore led to depletion in the Na solvation shell, which resulted in the accumulation of both Na ions (as inner-sphere complexes) and remaining hydrated water molecules at the mineral surface. This accumulation led to a decrease in both DNa and Dwater. In addition, the reduction in Dglucose as a function of increasing glucose content can be explained by the aggregation of glucose molecules into organic clusters H-bonded to the mineral surface on both walls of the nanopore. Experimental nuclear magnetic resonance and X-ray diffraction data were consistent with the theoretical predictions. Compared to clay interlayers devoid of glucose, increased intensities and new peaks in the 23Na nuclear magnetic resonance spectra confirmed increasing immobilization of Na as a function of increasing glucose content. And, the X-ray diffraction data indicated a reduced collapse of glucose-populated interlayers exposed to decreasing moisture conditions, which led to the maintenance of hydrated clay nanopores. The coupling of theoretical and experimental findings sheds light on the molecular to nanoscale mechanisms that

  18. Separation of advanced from mild fibrosis in diffuse liver disease using {sup 31}P magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Noren, Bengt [Department of Radiology, Linkoeping University, SE-581 85 Linkoeping (Sweden); Dahlqvist, Olof [Department of Radiation Physics, Linkoeping University, SE-581 85 Linkoeping (Sweden); Center for Medical Image Science and Visualization (CMIV), Linkoeping University, SE-581 85 Linkoeping (Sweden); Lundberg, Peter [Department of Radiology, Linkoeping University, SE-581 85 Linkoeping (Sweden); Department of Radiation Physics, Linkoeping University, SE-581 85 Linkoeping (Sweden); Center for Medical Image Science and Visualization (CMIV), Linkoeping University, SE-581 85 Linkoeping (Sweden)], E-mail: Peter.Lundberg@imv.liu.se; Almer, Sven [Department of Gastroenterology and Hepatology, Linkoeping University, SE-581 85 Linkoeping (Sweden); Kechagias, Stergios [Department of Internal Medicine, Linkoeping University, SE-581 85 Linkoeping (Sweden); Ekstedt, Mattias [Department of Gastroenterology and Hepatology, Linkoeping University, SE-581 85 Linkoeping (Sweden); Franzen, Lennart [Medilab, SE-183 53 Taeby Sweden (Sweden); Wirell, Staffan [Department of Radiology, Linkoeping University, SE-581 85 Linkoeping (Sweden); Smedby, Orjan [Department of Radiology, Linkoeping University, SE-581 85 Linkoeping (Sweden); Center for Medical Image Science and Visualization (CMIV), Linkoeping University, SE-581 85 Linkoeping (Sweden)

    2008-05-15

    {sup 31}P-MRS using DRESS was used to compare absolute liver metabolite concentrations (PME, Pi, PDE, {gamma}ATP, {alpha}ATP, {beta}ATP) in two distinct groups of patients with chronic diffuse liver disorders, one group with steatosis (NAFLD) and none to moderate inflammation (n = 13), and one group with severe fibrosis or cirrhosis (n = 16). All patients underwent liver biopsy and extensive biochemical evaluation. A control group (n = 13) was also included. Absolute concentrations and the anabolic charge, AC = {l_brace}PME{r_brace}/({l_brace}PME{r_brace} + {l_brace}PDE{r_brace}), were calculated. Comparing the control and cirrhosis groups, lower concentrations of PDE (p = 0.025) and a higher AC (p < 0.001) were found in the cirrhosis group. Also compared to the NAFLD group, the cirrhosis group had lower concentrations of PDE (p = 0.01) and a higher AC (p = 0.009). No significant differences were found between the control and NAFLD group. When the MRS findings were related to the fibrosis stage obtained at biopsy, there were significant differences in PDE between stage F0-1 and stage F4 and in AC between stage F0-1 and stage F2-3. Using a PDE concentration of 10.5 mM as a cut-off value to discriminate between mild, F0-2, and advanced, F3-4, fibrosis the sensitivity and specificity were 81% and 69%, respectively. An AC cut-off value of 0.27 showed a sensitivity of 93% and a specificity of 54%. In conclusion, the results suggest that PDE is a marker of liver fibrosis, and that AC is a potentially clinically useful parameter in discriminating mild fibrosis from advanced.

  19. Diffusion of copper in porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Andsager, D.; Hetrick, J.M.; Hilliard, J.; Nayfeh, M.H. [Department of Physics, 1110 West Green Street, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    1995-05-01

    We present a study on the nature of diffusion of copper in {ital p}-type porous silicon. The diffusion of evaporated copper in porous silicon and deposition of metal ions in aqueous solution through the porous network was measured by monitoring the metal concentration depth profile as a function of time using Auger electron spectroscopy. We observed that increasing metal penetration from copper evaporated samples correlates with quenching of photoluminescence, in agreement with previous ion quenching results. We extracted a diffusion coefficient from Auger concentration depth profiles which was seven orders of magnitude lower than that expected for diffusion of copper in bulk crystalline Si at room temperature. Deposition of ionic species cannot be characterized as a simple diffusion process. The observed deposition rates were strongly dependent on the solution concentration.

  20. Cropland Field Monitoring: MMV Page 1 Montana Cropland Enrolled Farm Fields Carbon Sequestration Field Sampling, Measurement, Monitoring, and Verification: Application of Visible-Near Infrared Diffuse Reflectance Spectroscopy (VNIR) and Laser-induced Breakdown Spectroscopy (LIBS)

    Energy Technology Data Exchange (ETDEWEB)

    Lee Spangler; Ross Bricklemyer; David Brown

    2012-03-15

    There is growing need for rapid, accurate, and inexpensive methods to measure, and verify soil organic carbon (SOC) change for national greenhouse gas accounting and the development of a soil carbon trading market. Laboratory based soil characterization typically requires significant soil processing, which is time and resource intensive. This severely limits application for large-region soil characterization. Thus, development of rapid and accurate methods for characterizing soils are needed to map soil properties for precision agriculture applications, improve regional and global soil carbon (C) stock and flux estimates and efficiently map sub-surface metal contamination, among others. The greatest gains for efficient soil characterization will come from collecting soil data in situ, thus minimizing soil sample transportation, processing, and lab-based measurement costs. Visible and near-infrared diffuse reflectance spectroscopy (VisNIR) and laser-induced breakdown spectroscopy (LIBS) are two complementary, yet fundamentally different spectroscopic techniques that have the potential to meet this need. These sensors have the potential to be mounted on a soil penetrometer and deployed for rapid soil profile characterization at field and landscape scales. Details of sensor interaction, efficient data management, and appropriate statistical analysis techniques for model calibrations are first needed. In situ or on-the-go VisNIR spectroscopy has been proposed as a rapid and inexpensive tool for intensively mapping soil texture and organic carbon (SOC). While lab-based VisNIR has been established as a viable technique for estimating various soil properties, few experiments have compared the predictive accuracy of on-the-go and lab-based VisNIR. Eight north central Montana wheat fields were intensively interrogated using on-the-go and lab-based VisNIR. Lab-based spectral data consistently provided more accurate predictions than on-the-go data. However, neither in situ

  1. Diffuse reflectance spectroscopy: diagnostic accuracy of a non-invasive screening technique for early detection of malignant changes in the oral cavity

    Science.gov (United States)

    Jayanthi, J L; Nisha, G U; Manju, S; Philip, E K; Jeemon, P; Baiju, K V; Beena, V T

    2011-01-01

    Background Strong proof-of-principle for utilisation of diffuse reflectance spectroscopy, a non-invasive tool for early detection of malignant changes, has emerged recently. The potential of this technique in distinguishing normal tissue from hyperplastic and dysplastic tissues was explored. Methods Diffuse reflectance (DR) spectra in the 400–700 nm region were obtained from the buccal mucosa of 96 patients and 34 healthy volunteers. The DR spectral data were compared against the gold standard biopsy and histopathology results. A principal-component analysis was performed for dimensional reduction in the normalised spectral data with linear discriminant analysis as the classifying technique. The receiver operator characteristic curve technique was employed for evaluating the performance of the diagnostic test. Results DR spectral features for different lesions, such as normal/healthy, hyperplastic, dysplastic and squamous cell carcinoma (SCC), varied significantly according to the intensity of oxygenated haemoglobin absorption. While the classification based on discriminant scores provided an overall sensitivity of 98.5% and specificity of 96.0% for distinguishing SCC from dysplasia, they were 100.0% and 95.0%, respectively, for distinguishing dysplasia from hyperplasia. Similarly, the analysis yielded a sensitivity of 95.0% and specificity of 100.0% for distinguishing hyperplasia from healthy tissue. The areas under the receiver operator characteristic curves were 0.98 (95% CI 0.95 to 1.00) and 0.95 (95% CI 0.90 to 1.00) for distinguishing dysplasia from SCC and hyperplasia from dysplasia, respectively. Conclusion DR spectral data efficiently discriminate healthy tissue from oral malignant lesions. Diagnostic accuracies obtained in this study highlight the potential use of this method for routine clinical practice. PMID:22021749

  2. Multimodal MRI in the characterization of glial neoplasms: the combined role of single-voxel MR spectroscopy, diffusion imaging and echo-planar perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zonari, Paolo [Ospedale ' ' B. Ramazzini' ' , AUSL Modena, Neuroradiologia, Dipartimento Integrato di Neuroscienze, Carpi, Modena (Italy); Baraldi, Patrizia [Universita degli Studi di Modena e Reggio Emilia, Dipartimento di Scienze Biomediche, Sezione di Fisiologia, Modena (Italy); Crisi, Girolamo [Azienda Ospedaliero-Universitaria di Parma, Dipartimento ad Attivita Integrata di Neuroscienze, Parma (Italy)

    2007-10-15

    Diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI) and MR spectroscopy (MRS) provide useful data for tumor evaluation. To assess the contribution of these multimodal techniques in grading glial neoplasms, we compared the value of DWI, PWI and MRS in the evaluation of histologically proven high- and low-grade gliomas in a population of 105 patients. Independently for each modality, the following variables were used to compare the tumors: minimum apparent diffusion coefficient (ADC) and maximum relative cerebral blood volume (rCBV) normalized values between tumor and healthy tissue, maximum Cho/Cr ratio and minimum NAA/Cr ratio in tumor, and scored lactate and lipid values in tumor. The Mann-Whitney and Wilcoxon tests were employed to compare DWI, PWI and MRS between tumor types. Logistic regression analysis was used to determine which parameters best increased the diagnostic accuracy in terms of sensitivity, specificity, and positive and negative predictive values. ROC curves were determined for parameters with high sensitivity and specificity to identify threshold values to separate high- from low-grade lesions. Statistically significant differences were found for rCBV tumor/normal tissue ratio, and NAA/Cr ratio in tumor and Cho/Cr ratio in tumor between low- and high-grade tumors. The best performing single parameter for group classification was the normalized rCBV value; including all parameters, statistical significance was reached by rCBV tumor/normal tissue ratio, NAA/Cr tumor ratio and lactate. From the ROC curves, a high probability for a neoplasm to be a high-grade lesion was associated with a rCBV tumor/normal tissue ratio of >1.16 and NAA/Cr tumor ratio of <0.44. Combining PWI and MRS with conventional MR imaging increases the accuracy of the attribution of malignancy to glial neoplasms. The best performing parameter was found to be the perfusion level. (orig.)

  3. Diffusing wave spectroscopy study of the colloidal interactions occurring between casein micelles and emulsion droplets: comparison to hard-sphere behavior.

    Science.gov (United States)

    Gaygadzhiev, Zafir; Corredig, Milena; Alexander, Marcela

    2008-04-15

    Understanding the underlying processes that govern interparticle interactions in colloidal systems is fundamental to predicting changes in their bulk properties. In this paper we discuss the colloidal behavior of casein micelles and protein-stabilized fat globules individually and in a mixture. The colloidal interactions were observed by transmission diffusing wave spectroscopy. The turbidity parameter, l*, and the diffusion coefficients of the samples studied were measured experimentally and compared to the theoretically calculated parameters for a hard-sphere system. The light scattering properties of casein micelles (volume fraction phi = 0.1-0.2) dispersed in milk permeate showed no deviation from the theoretically predicted model. Whey protein isolate (WPI)-stabilized emulsions (phi = 0.025-0.1) prepared either in milk permeate or in 5 mM imidazole buffer at pH 6.8 showed a behavior identical to that of the hard-sphere model. Similarly to the WPI-stabilized fat globules, the sodium caseinate (NaCas)-stabilized emulsions (phi = 0.025-0.1) prepared in milk permeate also showed resemblance to the theory. In contrast, NaCas-stabilized emulsions prepared in 5 mM imidazole buffer exhibited some discrepancy from the theoretically calculated parameters. The deviation from theory is attributed to the enhanced steric stabilization properties of these droplets in a low ionic strength environment. When recombined milks made from concentrated milk and WPI- and NaCas-stabilized droplets prepared in permeate (phi = 0.125-0.2) were studied, the experimental data showed a significant deviation from the theoretical behavior of a hard-sphere model due to mixing of two different species.

  4. Infrared spectroscopy as a tool to characterise starch ordered structure--a joint FTIR-ATR, NMR, XRD and DSC study.

    Science.gov (United States)

    Warren, Frederick J; Gidley, Michael J; Flanagan, Bernadine M

    2016-03-30

    Starch has a heterogeneous, semi-crystalline granular structure and the degree of ordered structure can affect its behaviour in foods and bioplastics. A range of methodologies are employed to study starch structure; differential scanning calorimetry, (13)C nuclear magnetic resonance, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). Despite the appeal of FTIR as a rapid, non-destructive methodology, there is currently no systematically defined quantitative relationship between FTIR spectral features and other starch structural measures. Here, we subject 61 starch samples to structural analysis, and systematically correlate FTIR spectra with other measures of starch structure. A hydration dependent peak position shift in the FTIR spectra of starch is observed, resulting from increased molecular order, but with complex, non-linear behaviour. We demonstrate that FTIR is a tool that can quantitatively probe short range interactions in starch structure. However, the assumptions of linear relationships between starch ordered structure and peak ratios are overly simplistic.

  5. Qualitative and simultaneous quantitative analysis of cimetidine polymorphs by ultraviolet-visible and shortwave near-infrared diffuse reflectance spectroscopy and multivariate calibration models.

    Science.gov (United States)

    Feng, Yuyan; Li, Xiangling; Xu, Kailin; Zou, Huayu; Li, Hui; Liang, Bing

    2015-02-01

    The object of the present study was to investigate the feasibility of applying ultraviolet-visible and shortwave near-infrared diffuse reflectance spectroscopy (UV-vis-SWNIR DRS) coupled with chemometrics in qualitative and simultaneous quantitative analysis of drug polymorphs, using cimetidine as a model drug. Three polymorphic forms (A, B and D) and a mixed crystal (M1) of cimetidine, obtained by preparation under different crystallization conditions, were characterized by microscopy, X-ray powder diffraction (XRPD) and infrared spectroscopy (IR). The discriminant models of four forms (A, B, D and M1) were established by discriminant partial least squares (PLS-DA) using different pretreated spectra. The R and RMSEP of samples in the prediction set by discriminant model with original spectra were 0.9959 and 0.1004. Among the quantitative models of binary mixtures (A and D) established by partial least squares (PLS) and least squares-support vector machine (LS-SVM) with different pretreated spectra, the LS-SVM models based on original and MSC spectra had better prediction effect with a R of 1.0000 and a RMSEP of 0.0134 for form A, and a R of 1.0000 and a RMSEP of 0.0024 for form D. For ternary mixtures, the established PLS quantitative models based on normalized spectra had relatively better prediction effect for forms A, B and D with R of 0.9901, 0.9820 and 0.9794 and RMSEP of 0.0471, 0.0529 and 0.0594, respectively. This research indicated that UV-vis-SWNIR DRS can be used as a simple, rapid, nondestructive qualitative and quantitative method for the analysis of drug polymorphs. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. In-situ investigation of the order-disorder transition in Cu2ZnSnSe4 by optical transmission spectroscopy

    Directory of Open Access Journals (Sweden)

    Christiane Stroth

    2017-02-01

    Full Text Available The existence of disorder is one possible reason for the limited performance of kesterite solar cells. Therefore further knowledge of the order-disorder phase transition, of factors which influence the degree of order and of methods to determine this material property is still required. In this study we investigated the order-disorder transition in the kesterite material Cu2ZnSnSe4 by in-situ optical transmission spectroscopy during heat treatments. We show in-situ results for the temperature dependence of the band gap and its tailing properties. The influence of cooling rates on the phase transition was analyzed as well as the ordering kinetics during annealing at a constant temperature. The critical temperature of the phase transition was determined and the existence of a control temperature range is shown, which allows for controlling the degree of order by the cooling rate within this range. Additionally we performed Raman analysis to link Raman spectra to the degree of order in Cu2ZnSnSe4. A correlation between the intensity ratio of A-modes as well as B-/ E- Raman modes and the degree of order was found.

  7. Quantifying aflatoxins in peanuts using fluorescence spectroscopy coupled with multi-way methods: Resurrecting second-order advantage in excitation-emission matrices with rank overlap problem.

    Science.gov (United States)

    Sajjadi, S Maryam; Abdollahi, Hamid; Rahmanian, Reza; Bagheri, Leila

    2016-03-05

    A rapid, simple and inexpensive method using fluorescence spectroscopy coupled with multi-way methods for the determination of aflatoxins B1 and B2 in peanuts has been developed. In this method, aflatoxins are extracted with a mixture of water and methanol (90:10), and then monitored by fluorescence spectroscopy producing EEMs. Although the combination of EEMs and multi-way methods is commonly used to determine analytes in complex chemical systems with unknown interference(s), rank overlap problem in excitation and emission profiles may restrain the application of this strategy. If there is rank overlap in one mode, there are several three-way algorithms such as PARAFAC under some constraints that can resolve this kind of data successfully. However, the analysis of EEM data is impossible when some species have rank overlap in both modes because the information of the data matrix is equivalent to a zero-order data for that species, which is the case in our study. Aflatoxins B1 and B2 have the same shape of spectral profiles in both excitation and emission modes and we propose creating a third order data for each sample using solvent as a new additional selectivity mode. This third order data, in turn, converted to the second order data by augmentation, a fact which resurrects the second order advantage in original EEMs. The three-way data is constructed by stacking augmented data in the third way, and then analyzed by two powerful second order calibration methods (BLLS-RBL and PARAFAC) to quantify the analytes in four kinds of peanut samples. The results of both methods are in good agreement and reasonable recoveries are obtained.

  8. Quantifying aflatoxins in peanuts using fluorescence spectroscopy coupled with multi-way methods: Resurrecting second-order advantage in excitation-emission matrices with rank overlap problem

    Science.gov (United States)

    Sajjadi, S. Maryam; Abdollahi, Hamid; Rahmanian, Reza; Bagheri, Leila

    2016-03-01

    A rapid, simple and inexpensive method using fluorescence spectroscopy coupled with multi-way methods for the determination of aflatoxins B1 and B2 in peanuts has been developed. In this method, aflatoxins are extracted with a mixture of water and methanol (90:10), and then monitored by fluorescence spectroscopy producing EEMs. Although the combination of EEMs and multi-way methods is commonly used to determine analytes in complex chemical systems with unknown interference(s), rank overlap problem in excitation and emission profiles may restrain the application of this strategy. If there is rank overlap in one mode, there are several three-way algorithms such as PARAFAC under some constraints that can resolve this kind of data successfully. However, the analysis of EEM data is impossible when some species have rank overlap in both modes because the information of the data matrix is equivalent to a zero-order data for that species, which is the case in our study. Aflatoxins B1 and B2 have the same shape of spectral profiles in both excitation and emission modes and we propose creating a third order data for each sample using solvent as a new additional selectivity mode. This third order data, in turn, converted to the second order data by augmentation, a fact which resurrects the second order advantage in original EEMs. The three-way data is constructed by stacking augmented data in the third way, and then analyzed by two powerful second order calibration methods (BLLS-RBL and PARAFAC) to quantify the analytes in four kinds of peanut samples. The results of both methods are in good agreement and reasonable recoveries are obtained.

  9. Use of NMR Imaging to Determine the Diffusion Coefficient of Water in Bio-based Hydrogels

    Science.gov (United States)

    The diffusion of liquid in a hydrogel material is a fundamental property which must be controlled in order to create effective delivery systems for the agricultural and pharmaceutical industries. NMR spectroscopy has been used to determine the diffusion of water and deuterium oxide in a bio-based h...

  10. On the performance of multiway methods for simultaneous quantification of two fluoroquinolones in urine samples by fluorescence spectroscopy and second-order calibration strategies

    Science.gov (United States)

    Vosough, Maryam; Eshlaghi, Sara Noroozi; Zadmard, Reza

    2015-02-01

    In the present work, the analytical performance of three multi-way algorithms has been evaluated. The proposed analytical problem was the simultaneous determination of moxifloxacin and ciprofloxacin in human urine samples using fluorescence spectroscopy. Parallel factor analysis (PARAFAC), self-weighted alternating trilinear decomposition (SWATLD) and unfolded partial least squares combined with the residual bilinearization procedure (U-PLS/RBL) have been compared, regarding their ability to solve the proposed problem. In this study, "second-order advantage" was also exploited for the mentioned algorithms through different calibration strategies. The three-way data was obtained via fluorescence spectroscopy, so that excitation-emission matrices (EEM) of the samples were recorded as the analytical signals. The accuracy and precision of each individual algorithm for analyzing the drugs in urine samples were compared using root mean square error of prediction (RMSEP), recovery and elliptical joint confidence region (EJCR) plots. The results revealed that each of the three algorithms could be applied for determination of moxifloxacin and ciprofloxacin, despite different EEM subsets and calibration strategies. However, better analytical performances were observed through PARAFAC and U-PLS/RBL modeling for MOX and CIP, respectively. So, by coupling the multi-way decomposition algorithms with fluorescence spectroscopy, a main part of preliminary sample preparation steps can be eliminated and experimental procedure might be significantly simplified, while achieving desirable analytical performance.

  11. Using optical fibers with different modes to improve the signal-to-noise ratio of diffuse correlation spectroscopy flow-oximeter measurements

    Science.gov (United States)

    He, Lian; Lin, Yu; Shang, Yu; Shelton, Brent J.; Yu, Guoqiang

    2013-03-01

    The dual-wavelength diffuse correlation spectroscopy (DCS) flow-oximeter is an emerging technique enabling simultaneous measurements of blood flow and blood oxygenation changes in deep tissues. High signal-to-noise ratio (SNR) is crucial when applying DCS technologies in the study of human tissues where the detected signals are usually very weak. In this study, single-mode, few-mode, and multimode fibers are compared to explore the possibility of improving the SNR of DCS flow-oximeter measurements. Experiments on liquid phantom solutions and in vivo muscle tissues show only slight improvements in flow measurements when using the few-mode fiber compared with using the single-mode fiber. However, light intensities detected by the few-mode and multimode fibers are increased, leading to significant SNR improvements in detections of phantom optical property and tissue blood oxygenation. The outcomes from this study provide useful guidance for the selection of optical fibers to improve DCS flow-oximeter measurements.

  12. The Diagnostic Ability of Follow-Up Imaging Biomarkers after Treatment of Glioblastoma in the Temozolomide Era: Implications from Proton MR Spectroscopy and Apparent Diffusion Coefficient Mapping

    Directory of Open Access Journals (Sweden)

    Martin Bulik

    2015-01-01

    Full Text Available Objective. To prospectively determine institutional cut-off values of apparent diffusion coefficients (ADCs and concentration of tissue metabolites measured by MR spectroscopy (MRS for early differentiation between glioblastoma (GBM relapse and treatment-related changes after standard treatment. Materials and Methods. Twenty-four GBM patients who received gross total resection and standard adjuvant therapy underwent MRI examination focusing on the enhancing region suspected of tumor recurrence. ADC maps, concentrations of N-acetylaspartate, choline, creatine, lipids, and lactate, and metabolite ratios were determined. Final diagnosis as determined by biopsy or follow-up imaging was correlated to the results of advanced MRI findings. Results. Eighteen (75% and 6 (25% patients developed tumor recurrence and pseudoprogression, respectively. Mean time to radiographic progression from the end of chemoradiotherapy was 5.8 ± 5.6 months. Significant differences in ADC and MRS data were observed between those with progression and pseudoprogression. Recurrence was characterized by N-acetylaspartate ≤ 1.5 mM, choline/N-acetylaspartate ≥ 1.4 (sensitivity 100%, specificity 91.7%, N-acetylaspartate/creatine ≤ 0.7, and ADC ≤ 1300 × 10−6 mm2/s (sensitivity 100%, specificity 100%. Conclusion. Institutional validation of cut-off values obtained from advanced MRI methods is warranted not only for diagnosis of GBM recurrence, but also as enrollment criteria in salvage clinical trials and for reporting of outcomes of initial treatment.

  13. Product mass transfer resistance directly determined during freeze-drying cycle runs using tunable diode laser absorption spectroscopy (TDLAS) and pore diffusion model.

    Science.gov (United States)

    Kuu, Wei Y; O'Bryan, Kevin R; Hardwick, Lisa M; Paul, Timothy W

    2011-08-01

    The pore diffusion model is used to express the dry layer mass transfer resistance, [Formula: see text], as a function of the ratio r(e)/?, where r(e) is the effective pore radius and ? is the tortuosity factor of the dry layer. Using this model, the effective pore radius of the dry layer can be estimated from the sublimation rate and product temperature profiles measured during primary drying. Freeze-drying cycle runs were performed using the LyoStar II dryer (FTS Systems), with real-time sublimation rate profiles during freeze drying continuously measured by tunable diode laser absorption spectroscopy (TDLAS). The formulations chosen for demonstration of the proposed approach include 5% mannitol, 5% sucrose, 5% lactose, 3% mannitol plus 2% sucrose, and a parenteral nutrition formulation denoted VitaM12. The three different methods used for determination of the product resistance are: (1) Using both the sublimation rate and product temperature profiles, (2) using the sublimation rate profile alone, and (3) using the product temperate profile alone. Unlike the second and third methods, the computation procedure of first method does not need solution of the complex heat and mass transfer equations.

  14. Advanced MRI increases the diagnostic accuracy of recurrent glioblastoma: Single institution thresholds and validation of MR spectroscopy and diffusion weighted MR imaging

    Directory of Open Access Journals (Sweden)

    Tomas Kazda

    2016-01-01

    Full Text Available The accurate identification of glioblastoma progression remains an unmet clinical need. The aim of this prospective single-institutional study is to determine and validate thresholds for the main metabolite concentrations obtained by MR spectroscopy (MRS and the values of the apparent diffusion coefficient (ADC to enable distinguishing tumor recurrence from pseudoprogression. Thirty-nine patients after the standard treatment of a glioblastoma underwent advanced imaging by MRS and ADC at the time of suspected recurrence — median time to progression was 6.7 months. The highest significant sensitivity and specificity to call the glioblastoma recurrence was observed for the total choline (tCho to total N-acetylaspartate (tNAA concentration ratio with the threshold ≥1.3 (sensitivity 100.0% and specificity 94.7%. The ADCmean value higher than 1313 × 10−6 mm2/s was associated with the pseudoprogression (sensitivity 98.3%, specificity 100.0%. The combination of MRS focused on the tCho/tNAA concentration ratio and the ADCmean value represents imaging methods applicable to early non-invasive differentiation between a glioblastoma recurrence and a pseudoprogression. However, the institutional definition and validation of thresholds for differential diagnostics is needed for the elimination of setup errors before implementation of these multimodal imaging techniques into clinical practice, as well as into clinical trials.

  15. [Study of the last glacial loess-like deposits in the coastal area of South China with diffuse reflectance spectroscopy and laser particle size analysis].

    Science.gov (United States)

    Wang, Jing; Chen, Zhen; Chen, Guo-neng

    2014-11-01

    Newly discovered yellow silt widely distributed in the coastal area of south China was analyzed using diffuse reflectance spectroscopy (DRS) and laser particle size (LPS) methods in the present paper. The authors take the lead in trying to synthetically judge the depositional environment, transporting agent and forming mechanism of the yellow silt from angles of output forms of iron minerals as well as grain size distribution features of the samples chose from three representative sections and a drill core. The DRS first derivative curves show the peak height of iron minerals decreasing from hematite (565 nm) to goethite (505 and 435 nm), which reflects a relatively dry, cold climate that coincides with the aeolian loess widely distributed in the northwest China, but reverses of the fluvial and marine deposits which experienced a well hydration in humid conditions over a long period of time in study area. LPS analysis show that grain size from top to bottom of the sections and drill core are homogeneous and typical of aeolian sediments. The grain size distribution in the yellow silt is characterized by double peaks with main peak of 10-50 μm and a secondary peak of landforms and buried topographies in the coastal area of south China have this kind of sediments, the yellow silt is considered to represent an aeolian deposit formed during the last glacial period, which is called "loess-like deposits" in our study.

  16. Diffuse Reflectance Spectroscopy of Hidden Objects, Part I: Interpretation of the Reflection-Absorption-Scattering Fractions in Near-Infrared (NIR) Spectra of Polyethylene Films.

    Science.gov (United States)

    Pomerantsev, Alexey L; Rodionova, Oxana Ye; Skvortsov, Alexej N

    2017-01-01

    Investigation of a sample covered by an interfering layer is required in many fields, e.g., for process control, biochemical analysis, and many other applications. This study is based on the analysis of spectra collected by near-infrared (NIR) diffuse reflectance spectroscopy. Each spectrum is a composition of a useful, target spectrum and a spectrum of an interfering layer. To recover the target spectrum, we suggest using a new phenomenological approach, which employs the multivariate curve resolution (MCR) method. In general terms, the problem is very complex. We start with a specific problem of analyzing a system, which consists of several layers of polyethylene (PE) film and underlayer samples with known spectral properties. To separate information originating from PE layers and the target, we modify the system versus both the number of the PE layers as well as the reflectance properties of the target sample. We consider that the interfering spectrum of the layer can be modeled using three components, which can be tentatively called transmission, absorption, and scattering contributions. The novelty of our approach is that we do not remove the reflectance and scattering effects from the spectra, but study them in detail aiming to use this information to recover the target spectrum.

  17. Highlighting the impact of aging on type I collagen: label-free investigation using confocal reflectance microscopy and diffuse reflectance spectroscopy in 3D matrix model.

    Science.gov (United States)

    Guilbert, Marie; Roig, Blandine; Terryn, Christine; Garnotel, Roselyne; Jeannesson, Pierre; Sockalingum, Ganesh D; Manfait, Michel; Perraut, François; Dinten, Jean-Marc; Koenig, Anne; Piot, Olivier

    2016-02-23

    During aging, alterations of extracellular matrix proteins contribute to various pathological phenotypes. Among these alterations, type I collagen cross-linking and associated glycation products accumulation over time detrimentally affects its physico-chemical properties, leading to alterations of tissue biomechanical stability. Here, different-age collagen 3D matrices using non-destructive and label-free biophotonic techniques were analysed to highlight the impact of collagen I aging on 3D constructs, at macroscopic and microscopic levels. Matrices were prepared with collagens extracted from tail tendons of rats (newborns, young and old adults) to be within the physiological aging process. The data of diffuse reflectance spectroscopy reveal that aging leads to an inhibition of fibril assembly and a resulting decrease of gel density. Investigations by confocal reflectance microscopy highlight poor-fibrillar structures in oldest collagen networks most likely related to the glycation products accumulation. Complementarily, an infrared analysis brings out marked spectral variations in the Amide I profile, specific of the peptidic bond conformation and for carbohydrates vibrations as function of collagen-age. Interestingly, we also highlight an unexpected behavior for newborn collagen, exhibiting poorly-organized networks and microscopic features close to the oldest collagen. These results demonstrate that changes in collagen optical properties are relevant for investigating the incidence of aging in 3D matrix models.

  18. Near-infrared diffuse reflectance spectroscopy with sample spots and chemometrics for fast determination of bovine serum albumin in micro-volume samples

    Institute of Scientific and Technical Information of China (English)

    Cai-Jing Cui; Wen-Sheng Cai; Xue-Guang Shao

    2013-01-01

    Near-infrared diffuse reflectance spectroscopy (NIRDRS) has attracted more and more attention in analyzing the components in samples with complex matrices.However,to apply this technique to micro-analysis,there are still some obstacles to overcome such as the low sensitivity and spectral overlapping associated with this approach.A method for fast determination of bovine serum albumin (BSA) in micro-volume samples was studied using NIRDRS with sample spots and chemometric techniques.10 μL of sample spotted on a filter paper substrate was used for the spectral measurements.Quantitative analysis was obtained by partial least squares (PLS) regression with signal processing and variable selection.The results show that the correlation coefficient (R) between the predicted and the reference concentration is 0.9897 and the recoveries are in the range of 87.4%-114.4% for the validation samples in the concentration range of 0.61-8.10 mg/mL.These results suggest that the method has the potential to quickly measure proteins in micro-volume solutions.

  19. Optimizing the models for rapid determination of chlorogenic acid, scopoletin and rutin in plant samples by near-infrared diffuse reflectance spectroscopy

    Science.gov (United States)

    Mao, Zhiyi; Shan, Ruifeng; Wang, Jiajun; Cai, Wensheng; Shao, Xueguang

    2014-07-01

    Polyphenols in plant samples have been extensively studied because phenolic compounds are ubiquitous in plants and can be used as antioxidants in promoting human health. A method for rapid determination of three phenolic compounds (chlorogenic acid, scopoletin and rutin) in plant samples using near-infrared diffuse reflectance spectroscopy (NIRDRS) is studied in this work. Partial least squares (PLS) regression was used for building the calibration models, and the effects of spectral preprocessing and variable selection on the models are investigated for optimization of the models. The results show that individual spectral preprocessing and variable selection has no or slight influence on the models, but the combination of the techniques can significantly improve the models. The combination of continuous wavelet transform (CWT) for removing the variant background, multiplicative scatter correction (MSC) for correcting the scattering effect and randomization test (RT) for selecting the informative variables was found to be the best way for building the optimal models. For validation of the models, the polyphenol contents in an independent sample set were predicted. The correlation coefficients between the predicted values and the contents determined by high performance liquid chromatography (HPLC) analysis are as high as 0.964, 0.948 and 0.934 for chlorogenic acid, scopoletin and rutin, respectively.

  20. Direct and simultaneous quantification of tannin mean degree of polymerization and percentage of galloylation in grape seeds using diffuse reflectance fourier transform-infrared spectroscopy.

    Science.gov (United States)

    Pappas, Christos; Kyraleou, Maria; Voskidi, Eleni; Kotseridis, Yorgos; Taranilis, Petros A; Kallithraka, Stamatina

    2015-02-01

    The direct and simultaneous quantitative determination of the mean degree of polymerization (mDP) and the degree of galloylation (%G) in grape seeds were quantified using diffuse reflectance infrared Fourier transform spectroscopy and partial least squares (PLS). The results were compared with those obtained using the conventional analysis employing phloroglucinolysis as pretreatment followed by high performance liquid chromatography-UV and mass spectrometry detection. Infrared spectra were recorded in solid state samples after freeze drying. The 2nd derivative of the 1832 to 1416 and 918 to 739 cm(-1) spectral regions for the quantification of mDP, the 2nd derivative of the 1813 to 607 cm(-1) spectral region for the degree of %G determination and PLS regression were used. The determination coefficients (R(2) ) of mDP and %G were 0.99 and 0.98, respectively. The corresponding values of the root-mean-square error of calibration were found 0.506 and 0.692, the root-mean-square error of cross validation 0.811 and 0.921, and the root-mean-square error of prediction 0.612 and 0.801. The proposed method in comparison with the conventional method is simpler, less time consuming, more economical, and requires reduced quantities of chemical reagents and fewer sample pretreatment steps. It could be a starting point for the design of more specific models according to the requirements of the wineries.

  1. Femtosecond time-resolved photoelectron spectroscopy with a vacuum-ultraviolet photon source based on laser high-order harmonic generation.

    Science.gov (United States)

    Wernet, Philippe; Gaudin, Jérôme; Godehusen, Kai; Schwarzkopf, Olaf; Eberhardt, Wolfgang

    2011-06-01

    A laser-based tabletop approach to femtosecond time-resolved photoelectron spectroscopy with photons in the vacuum-ultraviolet (VUV) energy range is described. The femtosecond VUV pulses are produced by high-order harmonic generation (HHG) of an amplified femtosecond Ti:sapphire laser system. Two generations of the same setup and results from photoelectron spectroscopy in the gas phase are discussed. In both generations, a toroidal grating monochromator was used to select one harmonic in the photon energy range of 20-30 eV. The first generation of the setup was used to perform photoelectron spectroscopy in the gas phase to determine the bandwidth of the source. We find that our HHG source has a bandwidth of 140 ± 40 meV. The second and current generation is optimized for femtosecond pump-probe photoelectron spectroscopy with high flux and a small spot size at the sample of the femtosecond probe pulses. The VUV radiation is focused into the interaction region with a toroidal mirror to a spot smaller than 100 × 100 μm(2) and the flux amounts to 10(10) photons/s at the sample at a repetition rate of 1 kHz. The duration of the monochromatized VUV pulses is determined to be 120 fs resulting in an overall pump-probe time resolution of 135 ± 5 fs. We show how this setup can be used to map the transient valence electronic structure in molecular dissociation. © 2011 American Institute of Physics

  2. Interfacial Chemical Composition and Molecular Order in Organic Photovoltaic Blend Thin Films Probed by Surface-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Razzell-Hollis, Joseph; Thiburce, Quentin; Tsoi, Wing C; Kim, Ji-Seon

    2016-11-16

    Organic electronic devices invariably involve transfer of charge carriers between the organic layer and at least one metal electrode, and they are sensitive to the local properties of the organic film at those interfaces. Here, we demonstrate a new approach for using an advanced technique called surface-enhanced raman spectroscopy (SERS) to quantitatively probe interfacial properties relevant to charge injection/extraction. Exploiting the evanescent electric field generated by a ∼7 nm thick layer of evaporated silver, Raman scattering from nearby molecules is enhanced by factors of 10-1000× and limited by a distance dependence with a measured decay length of only 7.6 nm. When applied to the study of an all-polymer 1:1 blend of P3HT and F8TBT used in organic solar cells, we find that the as-cast film is morphologically suited to charge extraction in inverted devices, with a top (anode) interface very rich in hole-transporting P3HT (74.5%) and a bottom (cathode) interface slightly rich in electron-transporting F8TBT (55%). While conventional, uninverted P3HT:F8TBT devices are reported to perform poorly compared to inverted devices, their efficiency can be improved by thermal annealing but only after evaporation of a metallic top electrode. This is explained by changes in composition at the top interface: annealing prior to silver evaporation leads to a greater P3HT concentration at the top interface to 83.3%, exaggerating the original distribution that favored inverted devices, while postevaporation annealing increases the concentration of F8TBT at the top interface to 34.8%, aiding the extraction of electrons in a conventional device. By nondestructively probing buried interfaces, SERS is a powerful tool for understanding the performance of organic electronic devices.

  3. A short-range ordering in soft magnetic Fe-based metallic glasses studied by Mössbauer spectroscopy and Reverse Monte Carlo method

    Science.gov (United States)

    Babilas, Rafał; Mariola, Kądziołka-Gaweł; Burian, Andrzej; Temleitner, László

    2016-05-01

    Selected soft magnetic amorphous alloys Fe80B20, Fe70Nb10B20 and Fe62Nb8B30 were produced by the melt-spinning and characterized by X-ray diffraction (XRD), transmission Mössbauer spectroscopy (MS), Reverse Monte Carlo modeling (RMC) and relative magnetic permeability measurements. The Mössbauer spectroscopy allowed to study the local environments of the Fe-centered atoms in the amorphous structure of binary and ternary glassy alloys. The MS provided also information about the changes in the amorphous structure due to the modification of chemical composition by various boron and niobium content. The RMC simulation based on the structure factors determined by synchrotron XRD measurements was also used in modeling of the atomic arrangements and short-range order in Fe-based model alloys. Addition of boron and niobium in the ternary model alloys affected the disorder in as-cast state and also influenced on the number of nearest neighbor Fe-Fe atoms, consequently. The distributions of Fe- and B-centered coordination numbers showed that N=10, 9 and 8 are dominated around Fe atoms and N=9, 8 and 7 had the largest population around B atoms in the examined amorphous alloys. Moreover, the relationship between the content of the alloying elements, the local atomic ordering and the magnetic permeability (magnetic after-effects) was mentioned.

  4. MR Imaging of Prostate Cancer: Diffusion Weighted Imaging and (3D Hydrogen 1 (1H MR Spectroscopy in Comparison with Histology

    Directory of Open Access Journals (Sweden)

    J. Yamamura

    2011-01-01

    Full Text Available Purpose. To evaluate retrospectively the impact of diffusion weighted imaging (DWI and (3D hydrogen 1 (1H MR-spectroscopy (MRS on the detection of prostatic cancer in comparison to histological examinations. Materials and Methods: 50 patients with suspicion of prostate cancer underwent a MRI examination at a 1.5T scanner. The prostate was divided into sextants. Regions of interest were placed in each sextant to evaluate the apparent diffusion coefficient (ADC-values. The results of the DWI as well as MRS were compared retrospectively with the findings of the histological examination. Sensitivity and specificity of ADC and metabolic ratio (MET—both separately and in combination—for identification of tumor tissue was computed for variable discrimination thresholds to evaluate its receiver operator characteristic (ROC. An association between ADC, MET and Gleason score was tested by the non-parametric Spearman -test. Results. The average ADC-value was 1.65±0.32mm2/s × 10-3 in normal tissue and 0.96±0.24 mm2/s × 10-3 in tumor tissue (mean ± 1 SD. MET was 0.418±0.431 in normal tissue and 2.010±1.649 in tumor tissue. The area under the ROC curve was 0.966 (95%-confidence interval 0.941–0.991 and 0.943 (0.918–0.968 for DWI and MRS, respectively. There was a highly significant negative correlation between ADC-value and the Gleason score in the tumor-positive tissue probes (=62, =−0.405, =.001. MRS did not show a significant correlation with the Gleason score (=0.117, =.366. By using both the DWI and MRS, the regression model provided sensitivity and specificity for detection of tumor of 91.9% and 98.3%, respectively. Conclusion. The results of our study showed that both DWI and MRS should be considered as an additional and complementary tool to the T2-weighted MRI for detecting prostate cancer.

  5. Optimal differentiation of high- and low-grade glioma and metastasis: a meta-analysis of perfusion, diffusion, and spectroscopy metrics

    Energy Technology Data Exchange (ETDEWEB)

    Usinskiene, Jurgita; Venius, Jonas; Rynkeviciene, Ryte; Norkus, Darius; Suziedelis, Kestutis [National Cancer Institute, Radiology Center, Vilnius (Lithuania); Ulyte, Agne [Vilnius University, Faculty of Medicine, Vilnius (Lithuania); Bjoernerud, Atle [Oslo University Hospital, Department of Physics, Oslo (Norway); Oslo University Hospital, The Intervention Centre, Oslo (Norway); Katsaros, Vasileios K. [General Anti-Cancer and Oncological Hospital ' ' St. Savvas' ' , Athens (Greece); Letautiene, Simona; Aleknavicius, Eduardas [National Cancer Institute, Radiology Center, Vilnius (Lithuania); Vilnius University, Faculty of Medicine, Vilnius (Lithuania); Rocka, Saulius [Vilnius University, Faculty of Medicine, Vilnius (Lithuania); Faculty of Medicine Vilnius University, Neuroangiosurgery Center, Vilnius (Lithuania); Usinskas, Andrius [Vilnius Gedimino Technical University, Department of Electronic Systems, Vilnius (Lithuania)

    2016-04-15

    To perform a meta-analysis of advanced magnetic resonance imaging (MRI) metrics, including relative cerebral blood volume (rCBV), normalized apparent diffusion coefficient (nADC), and spectroscopy ratios choline/creatine (Cho/Cr) and choline/N-acetyl aspartate (Cho/NAA), for the differentiation of high- and low-grade gliomas (HGG, LGG) and metastases (MTS). For systematic review, 83 articles (dated 2000-2013) were selected from the NCBI database. Twenty-four, twenty-two, and eight articles were included respectively for spectroscopy, rCBV, and nADC meta-analysis. In the meta-analysis, we calculated overall means for rCBV, nADC, Cho/Cr (short TE - from 20 to 35 ms, medium - from 135 to 144 ms), and Cho/NAA for the HGG, LGG, and MTS groups. We used random effects model to obtain weighted averages and select thresholds. Overall means (with 95 % CI) for rCBV, nADC, Cho/Cr (short and medium echo time, TE), and Cho/NAA were: for HGG 5.47 (4.78-6.15), 1.38 (1.16-1.60), 2.40 (1.67-3.13), 3.27 (2.78-3.77), and 4.71 (3.24-6.19); for LGG 2.00 (1.71-2.28), 1.61 (1.36-1.87), 1.46 (1.20-1.72), 1.71 (1.49-1.93), and 2.36 (1.50-3.23); for MTS 5.06 (3.85-6.27), 1.35 (1.06-1.64), 1.89 (1.72-2.06), 3.14 (1.57-4.72), (Cho/NAA was not available). LGG had significantly lower rCBV, Cho/Cr, and Cho/NAA values than HGG or MTS. No significant differences were found for nADC. Best differentiation between HGG and LGG is obtained from rCBV, Cho/Cr, and Cho/NAA metrics. MTS could not be reliably distinguished from HGG by the methods investigated. (orig.)

  6. Vibrational spectroscopies: a natural ''mesoscope'' for the study of spontaneous ordering in alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chafi, Allal; Souhabi, Jihane; Pages, Olivier; Postnikov, Andrei; Gleize, Jerome [LPMD, Universite Paul Verlaine - Metz, 1 Bd Arago, 57078 Metz (France); Sallet, V. [GEMAC-CNRS, 1 Pl. Briand, 92195 Meudon (France); Li, L.H.; Harmand, J.C. [LPN-CNRS, Route de Nozay, 91460 Marcoussis (France)

    2009-05-15

    The novel paradigm of a 1-bond{yields}2-mode percolation-type behavior for the lattice dynamics at the zone-centre of random semiconductor alloys, that mirrors a lattice relaxation of the similar 1-bond{yields}2-length type, opens an attractive area for a (re-)discussion of spontaneous long-range clustering/anticlustering in terms of purely intrinsic effects. As examples, we show in this work how such antagonist effects as CuPt type spontaneous ordering of InGaP{sub 2} and N-induced In-anticlustering far from N-impurities in (N,In)-dilute InGaAsN can be discussed/evidenced from the transverse optical vibration spectra. The whole discussion is supported by full contour modelling of the TO Raman lineshapes via our percolation model. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Combined phase-field and MD simulations of diffusion drop and ordering at [Ni{sub x}Zr{sub 1-x}]{sub liquid}-Zr{sub crystal} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Guerdane, M.; Wendler, F.; Nestler, B. [Institute of Materials and Processes, Karlsruhe University of Applied Sciences (Germany)

    2010-07-01

    We combine phase-field (PF) modeling and molecular dynamics (MD) simulations to show that the velocity of the solidification front in a two-phase [Ni{sub x}Zr{sub 1-x}]{sub liquid}-Zr{sub crystal} structure is strongly affected by the drop of the liquid diffusion when approaching the solid-liquid interface. The latter is defined through a suitable order parameter that distinguishes between crystalline and liquid atomic environment. The diffusion drop near the interface is attributed to the pronounced short range order inherent to the Ni{sub x}Zr{sub 1-x} melt. The system transforms into a massive lateral ordering in the vicinity of the Zr crystalline wall. Our combined PF-MD analysis points out the shortcoming of the standard interpolation procedure, usually applied in constructing the phase dependent diffusivity, to describe the confinement effect caused by the crystalline wall at low temperatures.

  8. Structural and surface coverage effects on CO oxidation reaction over carbon-supported Pt nanoparticles studied by quadrupole mass spectrometry and diffuse reflectance FTIR spectroscopy.

    Science.gov (United States)

    Cheah, Seng Kian; Bernardet, Véronique P; Franco, Alejandro A; Lemaire, Olivier; Gelin, Patrick

    2016-06-01

    The CO oxidation reaction on carbon-supported Pt nanoparticles (average size of 2.8 to 7.7 nm) was studied under flowing conditions at atmospheric pressure and temperatures between 300 and 353 K by coupling quadrupole mass spectrometry (QMS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The Pt loading was varied between 20 and 60 wt%. Gases diluted in He (0.5 mol%) were used together with Ar as a tracer. Reactions with CO and O2 introduced separately onto the samples were studied by QMS, applying successive step changes of the reaction mixtures. Variations in the rate of the reactions were observed and correlated with changes of the calculated coverage of the Pt surface by CO and/or O adspecies at varying steps of the experiment. The transient reaction of CO(g) with adsorbed O (Oad) was fast and mass transport-limited while that of O2(g) with adsorbed CO (COad) was sluggish. Following the same experimental procedures, FTIR spectra of adsorbed CO after varying steps were recorded, confirming the variations of COad and Oad as determined by QMS and indicating changes in the CO distribution over varying types of Pt surface sites. The influence of the adlayer composition (co-adsorption of COad and Oad), the particle size/structure and some possible surface reconstruction effects on the CO oxidation rate were evidenced and discussed. The structure of the Pt nanoparticles supported on carbon appears as an important factor for the efficiency of the so-called O2 bleeding as a CO mitigation strategy in polymer electrolyte membrane fuel cells.

  9. Assessing saffron (Crocus sativus L.) adulteration with plant-derived adulterants by diffuse reflectance infrared Fourier transform spectroscopy coupled with chemometrics.

    Science.gov (United States)

    Petrakis, Eleftherios A; Polissiou, Moschos G

    2017-01-01

    Saffron, the dried red stigmas of the plant Crocus sativus L., is well-known as one of the most important and expensive spices worldwide. It is thus highly susceptible to fraudulent practices that employ, among others, plant-derived adulterants. This study presents an application of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and chemometric techniques for evaluating adulteration of saffron with six characteristic adulterants of plant origin, i.e. C. sativus stamens, calendula, safflower, turmeric, buddleja, and gardenia. The proposed method involved a three-step process for the detection of adulteration as well as for the identification and quantification of adulterants. Partial least squares discriminant analysis (PLS-DA) was applied to perform authentication of saffron based on mid-infrared fingerprints (4000-600cm(-1)), resulting in 99% correct classification of pure saffron and saffron adulterated at 5-20% (w/w) levels. Adulterant identification in positive samples was performed with high sensitivity and specificity by a six-class PLS-DA model, with spectroscopic data from the region 2000-600cm(-1). Subsequently, partial least squares (PLS) regression models were built for the quantification of each adulterant. By using synergy interval PLS (siPLS) for variable selection, models with improved performance were developed, with detection limits ranging from 1.0% to 3.1% (w/w). The results obtained illustrate that this strategy based on DRIFTS has the potential to complement existing methodologies for the rapid and cost-effective assessment of typical saffron frauds.

  10. Spin-resolved photoelectron spectroscopy using femtosecond extreme ultraviolet light pulses from high-order harmonic generation

    Science.gov (United States)

    Plötzing, M.; Adam, R.; Weier, C.; Plucinski, L.; Eich, S.; Emmerich, S.; Rollinger, M.; Aeschlimann, M.; Mathias, S.; Schneider, C. M.

    2016-04-01

    The fundamental mechanism responsible for optically induced magnetization dynamics in ferromagnetic thin films has been under intense debate since almost two decades. Currently, numerous competing theoretical models are in strong need for a decisive experimental confirmation such as monitoring the triggered changes in the spin-dependent band structure on ultrashort time scales. Our approach explores the possibility of observing femtosecond band structure dynamics by giving access to extended parts of the Brillouin zone in a simultaneously time-, energy- and spin-resolved photoemission experiment. For this purpose, our setup uses a state-of-the-art, highly efficient spin detector and ultrashort, extreme ultraviolet light pulses created by laser-based high-order harmonic generation. In this paper, we present the setup and first spin-resolved spectra obtained with our experiment within an acquisition time short enough to allow pump-probe studies. Further, we characterize the influence of the excitation with femtosecond extreme ultraviolet pulses by comparing the results with data acquired using a continuous wave light source with similar photon energy. In addition, changes in the spectra induced by vacuum space-charge effects due to both the extreme ultraviolet probe- and near-infrared pump-pulses are studied by analyzing the resulting spectral distortions. The combination of energy resolution and electron count rate achieved in our setup confirms its suitability for spin-resolved studies of the band structure on ultrashort time scales.

  11. Cross diffusion and MHD effects on a high order chemically reactive micropolar fluid of naturally convective heat and mass transfer past through an infinite vertical porous medium with a constant heat sink

    Science.gov (United States)

    Arifuzzaman, S. M.; Rana, B. M. Jewel; Ahmed, R.; Ahmmed, S. F.

    2017-06-01

    High order chemically reactive micropolar fluid flow through an infinite vertical porous medium with thermal diffusion, mass diffusion, MHD, thermal radiation and heat sink has been studied. A flow model is established by employing the well-known boundary layer approximations. In order to obtain non-dimensional system of equations, a similarity transformation is applied on the flow model. The stability and convergence analysis have been analyzed. The obtained non-dimensional equations have been solved by explicit finite difference method. The effects of various parameters entering into the problem on velocity, angular velocity, temperature and concentration are shown graphically.

  12. Hard x-ray photoelectron spectroscopy study of As and Ga out-diffusion in In{sub 0.53}Ga{sub 0.47}As/Al{sub 2}O{sub 3} film systems

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, C.; Woicik, J. C. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Lysaght, P.; Price, J.; Huang, J. [SEMATECH, 257 Fuller Rd., Albany, New York 12203 (United States)

    2012-08-06

    Hard x-ray photoelectron spectroscopy (HAXPES) was performed on In{sub 0.53}Ga{sub 0.47}As/Al{sub 2}O{sub 3} gate stacks as deposited and annealed at 400 Degree-Sign C, 500 Degree-Sign C, and 700 Degree-Sign C to test for out-diffusion of substrate elements. Ga and As core-level intensities increase with increasing anneal temperature, while the In intensity decreases. HAXPES was performed at two different beam energies to vary the surface sensitivity; results demonstrate Ga and As out-diffuse into the Al{sub 2}O{sub 3} film. Analysis suggests the presence of an interlayer containing Ga and As oxides, which thickens with increasing anneal temperature. Further diffusion, especially of Ga, into the Al{sub 2}O{sub 3} film is also observed with increasing anneal temperature.

  13. Separation of multiple-quantum signals with different orders along with frequency axis in Raman magnetic resonance spectroscopy in heteronuclear systems

    Institute of Scientific and Technical Information of China (English)

    缪希茄; 卢广; 叶朝辉

    1997-01-01

    One-dimensional multiple-quantum spectroscopy with Raman magnetic resonance (RMR) in het-eronuclear systems was described by the product operator formalism in detail.The effects of the field strength and the frequency offset of the irradiation introduced during the detection period on the intensities and the resonant frequencies of the multiple-quantum signals in RMR spectra were investigated extensively by this product operator formalism.The results predicted by the formalism showed that the multiple-quantum signals in RMR spectroscopy had a higher sensitivity when a smaller frequency offset of irradiation field was employed.However,this situation would complicate the assignment and the separation of the multiple-quantum signals in different orders along the frequency axis in RMR spectra.On the other hand,a larger strength of the irradiation field would result in decoupling and therefore would obscure the detection of the multiple-quantum signals.In the meantime,a much weaker RF field might greatly dec

  14. Detection limits for blood on four fabric types using infrared diffuse reflection spectroscopy in mid- and near-infrared spectral windows.

    Science.gov (United States)

    DeJong, Stephanie A; Lu, Zhenyu; Cassidy, Brianna M; O'Brien, Wayne L; Morgan, Stephen L; Myrick, Michael L

    2015-09-01

    Detection limits (DL) for blood on four fabric types were estimated for calibrations derived using partial least squares regression applied to infrared (IR) diffuse reflection spectra. Samples were prepared by dip-coating acrylic, cotton, nylon, and polyester fabrics from solutions of diluted rat blood. While DLs often appear in terms of dilution factor in the forensic community, mass percentage, coverage (mass per unit area), or film thickness are often more relevant when comparing experimental methods. These alternate DL units are related to one another and presented here. The best IR diffuse reflection DLs for blood on acrylic and cotton fabrics were in the mid-IR spectral window corresponding to the protein Amide I/II absorption bands. These DLs were dilution by a factor of 2300 (0.019% w/w blood solids) for acrylic and a factor of 610 (0.055% w/w blood solids) for cotton. The best DL for blood on polyester was found in the mid-IR spectral window corresponding to the protein Amide A absorption band at dilution by a factor of 900 (0.034% w/w blood solids). Because of the similarity between the IR spectra of blood solids and nylon fabrics, no satisfactory IR DLs were determined for the calibration of blood on nylon. We compare our values to DLs reported for blood detection using the standard luminol method. The most commonly reported luminol DLs are of the order of 1000-fold dilution, which we estimate are a factor of 2-7 lower than our reported IR DLs on a coverage basis.

  15. Application of Near Infrared Diffuse Reflectance Spectroscopy with Radial Basis Function Neural Network to Determination of Rifampincin Isoniazid and Pyrazinamide Tablets

    Institute of Scientific and Technical Information of China (English)

    DU Lin-na; WU Li-hang; LU Jia-hui; GUO Wei-liang; MENG Qing-fan; JIANG Chao-jun; SHEN Si-le; TENG Li-rong

    2007-01-01

    Partial least squares(PLS), back-propagation neural network (BPNN) and radial basis function neural network(RBFNN) were respectively used for estalishing quantative analysis models with near infrared(NIR) diffuse reflectance spectra for determining the contents of rifampincin(RMP), isoniazid(INH) and pyrazinamide(PZA) in rifampicin isoniazid and pyrazinamide tablets. Savitzky-Golay smoothing, first derivative, second derivative, fast Fourier transform(FFT) and standard normal variate(SNV) transformation methods were applied to pretreating raw NIR diffuse reflectance spectra. The raw and pretreated spectra were divided into several regions, depending on the average spectrum and RSD spectrum. Principal component analysis(PCA) method was used for analyzing the raw and pretreated spectra in different regions in order to reduce the dimensions of input data. The optimum spectral regions and the models' parameters were chosen by comparing the root mean square error of cross-validation(RMSECV) values which were obtained by leave-one-out cross-validation method. The RMSECV values of the RBFNN models for determining the contents of RMP, INH and PZA were 0.00288, 0.00226 and 0.00341, respectively. Using these models for predicting the contents of INH, RMP and PZA in prediction set, the RMSEP values were 0.00266, 0.00227 and 0.00411, respectively. These results are better than those obtained from PLS models and BPNN models. With additional advantages of fast calculation speed and less dependence on the initial conditions, RBFNN is a suitable tool to model complex systems.

  16. Subnanosecond spectral diffusion measurement using photon correlation

    CERN Document Server

    Sallen, Gregory; Aichele, Thomas; André, Régis; Besombes, Lucien; Bougerol, Catherine; Richard, Maxime; Tatarenko, Serge; Kheng, Kuntheak; Poizat, Jean-Philippe; 10.1038/nphoton.2010.174

    2012-01-01

    Spectral diffusion is a result of random spectral jumps of a narrow line as a result of a fluctuating environment. It is an important issue in spectroscopy, because the observed spectral broadening prevents access to the intrinsic line properties. However, its characteristic parameters provide local information on the environment of a light emitter embedded in a solid matrix, or moving within a fluid, leading to numerous applications in physics and biology. We present a new experimental technique for measuring spectral diffusion based on photon correlations within a spectral line. Autocorrelation on half of the line and cross-correlation between the two halves give a quantitative value of the spectral diffusion time, with a resolution only limited by the correlation set-up. We have measured spectral diffusion of the photoluminescence of a single light emitter with a time resolution of 90 ps, exceeding by four orders of magnitude the best resolution reported to date.

  17. Artifact-Free and Detection-Profile-Independent Higher-Order Fluorescence Correlation Spectroscopy for Microsecond-Resolved Kinetics. 2. Mixtures and Reactions.

    Science.gov (United States)

    Abdollah-Nia, Farshad; Gelfand, Martin P; Van Orden, Alan

    2017-03-23

    Fluorescence correlation spectroscopy (FCS) is a primary tool in the time-resolved analysis of nonreacting or reacting molecules in solution, based on fluorescence intensity fluctuations. However, conventional FCS alone is insufficient for a complete determination of reaction or mixture parameters. In an accompanying article, a technique for the computation of artifact-free higher-order correlations with microsecond time resolution was described. Here, we demonstrate the applications of the technique to analyze the systems of fast and slow reactions. As an example of non- or slow-reacting systems, the technique is applied to resolve two-component mixtures of labeled oligonucleotides. Next, the protonation reaction of fluorescein isothiocyanate in phosphate buffer is analyzed as an example of fast reactions (relaxation time system, the simple factorized form of cumulant-based higher-order correlations is exploited to remove the dependence on the molecular detection function (MDF). Therefore, there is no need to model and characterize the experimental MDF, and the precision and the accuracy of the technique are enhanced. It is verified that the higher-order correlation analysis enables a complete and simultaneous determination of the number and brightness parameters of mixing or reacting molecules, the reaction relaxation time, and forward and reverse reaction rates.

  18. Diffuse ferroelectric transition and relaxational dipolar freezing in (Ba, Sr)TiO{sub 3:} III. Role of order parameter fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Neelam; Pandey, Dhanajai [School of Materials Science and Technology, Banaras Hindu University, Vanarasi (India); Singh, Anirudh P. [Shaheed Bhagat Singh College of Engineering and Technology, Ferozpor (India); Durga Prasad, Ch. [Naval Materials Research Laboratory, Naval Dockyard, Bombay (India)

    1996-10-07

    Results of a high-temperature x-ray powder diffraction study of the phase transition between cubic and tetragonal phases of (Ba{sub 1-x}Sr{sub x})TiO{sub 3} are presented for x=0.08 and 0.12 which exhibit sharp and diffuse dielectric anomalies, respectively. Experimental evidence and arguments are advanced to show that the cubic and tetragonal phases coexist over a wide range of temperatures and that this coexistence is due to the fluctuation of the order parameter which is coupled electrostrictively to strains. For x=0.08, the phase coexistence disappears below the dielectric anomaly temperature T{sub m}', indicating the critical nature of the fluctuations. For x=0.12, these fluctuations are non-critical since the phase coexistence persists even below T{sub m}'. The complete conversion to the tetragonal phase occurs at T{sub s} approx. 7.5 deg. C which is nearly 25 deg. C lower than T{sub m}'(= 102 {+-} 1 deg. C). It is shown that the spontaneous polarization also increases gradually below T{sub m}' and levels off at T{sub p} {approx} 75 deg C. The existence of structural and polarization anomalies well below the frequency-independent dielectric anomaly temperature T{sub m}' cannot be rationalized either in terms of the Landau-like theories for ferroelectric transitions which predict T{sub s}=T{sub p}T{sub m}' or in terms of dipole glass transitions and/or relaxor ferroelectric transitions for which T{sub m}' should be frequency dependent. (author)

  19. [Determination of Trace Lead in Water by UV-Visible Diffuse Reflectance Spectroscopy Combined with Surfactant and Membrane Filtration-Enrichment].

    Science.gov (United States)

    Zhang, Xiao-fang; Zhu, Bi-lin; Li, Wei; Wang, Lei; Zhang, Lei; Wu, Ting; Du, Yi-ping

    2015-07-01

    In this paper, a method of determination of trace lead in water by UV-Visible diffuse reflectance spectroscopy combined with surfactant and membrane filtration enrichment was proposed. In the NH3 x H2O-NH4Cl buffer solution with pH 8.5, the lead(II) ion would react with dithizone to form the red complex under vigorous stirring, which is hydrophobic and can be enriched by the mixed cellulose ester membrane. In addition, the nonionic surfactant Polyoxyethylene lauryl ether (Brij-30) was added into the solution to improve the enrichment efficiency, then visible diffuse reflectance spectra of the membrane were measured directly after the membrane were naturally dried. We also optimized the reaction conditions which may affect the complexation reaction process, such as type of surfactants, the concentration of the surfactant, the reaction acidity, the concentration of dithizone as well as the reaction time. The research results show that under the optimum conditions, a good linear correlation between absorbance at 485 nm and concentration of lead in the range of 5.0-100.0 microg x L(-1) was obtained with a squared correlation coefficient (R2) of 0.9906, and the detection limit was estimated accordingly to be 2.88 microg x L(-1). To determine real water sample, the interference from some potential coexisting ions was also studied at the optimal conditions when the concentration of lead (II) ion standard solution was fixed to 20 microg x L(-1). The results indicate that the following ions cannot interfere in the determination of lead with the proposed method: 500 times of the K+, Na+, Ca2+, Mg2+, NH4+, NO3-, Cl-, CH3COO-, SO4(2-); 10 times of the Al3+ (using 10% NaF as a masking reagent to avoid the interference); 10 times of the Fe3+ (using 10% NaF and 10% sodium potassium tartrate as masking reagents); 10 times of Hg2+ or Zn2+ (using 10% NaSCN and 10% potassium sodium tartrate as masking reagents); the same amount of Cd2+, Cu2+. The proposed method was applied to the

  20. Investigation of fluctuations of the oxygen order in YBa sub 2 Cu sub 3 O sub x near the orthorhombic-to-tetragonal phase transition using mechanical spectroscopy

    CERN Document Server

    Foos, K

    2000-01-01

    given above. YBa-2Cu-3O-x (concentrations x between 6 and 7) has a tetragonal and a number of orthorhombic structures that correspond to different oxygen configurations in the Cu(1) planes. The oxygen atoms in these planes occupy two types of interstitial sites. In the tetragonal phase, both types of sites are occupied with same probability, whereas the occupation probabilities differ in the orthorhombic phases. Thus the tetragonal-to-orthorhombic phase transition is combined with an disorder-to-order transition. It is, at least above 600 K, of second order. At the transition the amplitude and the correlation time of the fluctuations of the oxygen configuration should diverge. This macroscopic yields ferroelastic behavior and critical slowing-down of the inelastic relaxation rate, respectively. This work gives evidences for this behavior. We studied energy dissipation and elastic modulus behavior of YBa-2Cu-3O-x samples by mechanical spectroscopy (temperatures from 400 to 1000 K, vibrating reed technique, fre...

  1. Tellurium speciation, connectivity, and chemical order in As(x)Te(100-x) glasses: results from two-dimensional 125Te NMR spectroscopy.

    Science.gov (United States)

    Kaseman, Derrick C; Hung, Ivan; Lee, Kathleen; Kovnir, Kirill; Gan, Zhehong; Aitken, Bruce; Sen, Sabyasachi

    2015-02-05

    The short-range structure, connectivity, and chemical order in As(x)Te(100-x) (25 ≤ x ≤ 65) glasses are studied using high-resolution two-dimensional projection magic-angle-turning (pjMAT) (125)Te nuclear magnetic resonance (NMR) spectroscopy. The (125)Te pjMAT NMR results indicate that the coordination of Te atoms obeys the 8-N coordination rule over the entire composition range. However, in strong contrast with the analogous glass-forming As-S and As-Se chalcogenides, significant violation of chemical order is observed in As-Te glasses over the entire composition range in the form of homopolar As-As (Te-Te) bonds, even in severely As (Te)-deficient glasses. The speciation of the Te coordination environments can be explained with the dissociation reaction model As2Te3 → 2As + 3Te(II), characterized by a dissociation constant that is independent of glass composition. These structural characteristics can be attributed to the high metallicity of Te and the strong energetic similarity between the Te-Te, Te-As, and As-As bonds, and they are consistent with the monotonic and often nearly linear variation of physical properties observed in telluride glasses as a function of the Te content.

  2. Effects of the structural order of canthaxanthin on the Raman scattering cross section in various solvents:A study by Raman spectroscopy and ab initio calculation

    Institute of Scientific and Technical Information of China (English)

    Wu Nan-Nan; Li Zuo-Wei; Liu Jing-Yao; OuYang Shun-Li

    2012-01-01

    In this work,we measure the Raman scattering cross sections (RSCSs) of the carbon-carbon (CC) stretching vibrational modes of canthaxanthin in benzene,acetone,n-heptane,cyclohexane,and m-xylene.It is found that the absolute RSCS of CC stretching mode of canthaxanthin reaches a value of 10-24 cm2·molecule-1·sr-1 at 8×10-5 M,which is 6 orders of magnitude larger than general RSCS (10-30 cm2·molecule- 1 ·sr-1 ),and the RSCSs of canthaxanthin in various solvents are very different due to the hydrogen bond.A theoretical interpretation of the magnetic experimental results is given,which is introduced in a qualitative nonlinear model of coherent weakly damped electron-lattice vibration in the structural order of polyene chains.In addition,the optimal structure and the bond length alternation (BLA) parameter of canthaxanthin are calculated using quantum chemistry calculation (at the b31yp/6-31g (d,p) level of theory).The theoretical calculations are in good agreement with the experimental results.Furthermore,the combination of Raman spectroscopy and the quantum chemistry calculation study would be a quite suitable method of studying the structures and the properties of the π-conjugated systems.

  3. High-order nonlinear optical processes in ablated carbon-containing materials: Recent approaches in development of the nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range

    Science.gov (United States)

    Ganeev, R. A.

    2017-08-01

    The nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range became a versatile tool for the analysis of the optical, structural and morphological properties of matter. The carbon-contained materials have shown the advanced properties among other studied species, which allowed both the definition of the role of structural properties on the nonlinear optical response and the analysis of the fundamental features of carbon as the attractive material for generation of coherent short-wavelength radiation. We review the studies of the high-order harmonic generation by focusing ultrashort pulses into the plasmas produced during laser ablation of various organic compounds. We discuss the role of ionic transitions of ablated carbon-containing molecules on the harmonic yield. We also show the similarities and distinctions of the harmonic and plasma spectra of organic compounds and graphite. We discuss the studies of the generation of harmonics up to the 27th order (λ = 29.9 nm) of 806 nm radiation in the boron carbide plasma and analyze the advantages and disadvantages of this target compared with the ingredients comprising B4C (solid boron and graphite) by comparing plasma emission and harmonic spectra from three species. We also show that the coincidence of harmonic and plasma emission wavelengths in most cases does not cause the enhancement or decrease of the conversion efficiency of this harmonic.

  4. Mixture resolution according to the percentage of robusta variety in order to detect adulteration in roasted coffee by near infrared spectroscopy.

    Science.gov (United States)

    Pizarro, C; Esteban-Díez, I; González-Sáiz, J M

    2007-03-07

    Near infrared spectroscopy (NIRS), combined with multivariate calibration methods, has been used to quantify the robusta variety content of roasted coffee samples, as a means for controlling and avoiding coffee adulteration, which is a very important issue taking into account the great variability of the final sale price depending on coffee varietal origin. In pursuit of this aim, PLS regression and a wavelet-based pre-processing method that we have recently developed called OWAVEC were applied, in order to simultaneously operate two crucial pre-processing steps in multivariate calibration: signal correction and data compression. Several pre-processing methods (mean centering, first derivative and two orthogonal signal correction methods, OSC and DOSC) were additionally applied in order to find calibration models with as best a predictive ability as possible and to evaluate the performance of the OWAVEC method, comparing the respective quality of the different regression models constructed. The calibration model developed after pre-processing derivative spectra by OWAVEC provided high quality results (0.79% RMSEP), the percentage of robusta variety being predicted with a reliability notably better than that associated with the models constructed from raw spectra and also from data corrected by other orthogonal signal correction methods, and showing a higher model simplicity.

  5. Rapid and Noninvasive Detection of Skin Cholesterol with Diffuse Reflectance Spectroscopy Technology%漫反射光谱技术快速无创检测皮肤胆固醇

    Institute of Scientific and Technical Information of China (English)

    候华毅; 董美丽; 王贻坤; 朱灵; 马祖长; 刘勇

    2016-01-01

    针对皮肤胆固醇无创检测的迫切需求,设计了一种基于微型光谱仪的便携式和智能化的皮肤漫反射光谱实时测量系统。配制毛地黄皂苷—辣根过氧化物酶共聚物溶液,利用毛地黄皂苷可与皮肤胆固醇分子中的羟基特异性结合和辣根过氧化物酶能与TMB试剂(主要成分为3,3’,5,5’-四甲基联苯胺)反应显色的特性,实现皮肤胆固醇的高灵敏和高特异的识别与指示,并通过测量反应后颜色的变化程度来定量皮肤胆固醇的浓度。以与人体皮肤结构相近的猪皮肤为实验对象,采用萃取法获得梯度浓度的胆固醇样本,利用上述光谱测量系统检测样本内的胆固醇浓度来验证该方法的可行性。实验结果显示,相对漫反射率能够区分不同浓度的胆固醇样本,在特征单波长(442,450和463 nm)处和特征波段442~500 nm内,漫反射率强度因子均可以定量反映样本内的胆固醇浓度,经线性拟合,判定系数R2分别为0.960,0.959,0.958和0.958。研究结果表明,使用漫反射光谱技术可以实现皮肤胆固醇的快速无创检测,将其应用于动脉粥样硬化性疾病风险评估,对于该类疾病的防控具有重要意义。%Due to the urgent need for noninvasive detection of skin cholesterol,a portable,intelligent and real-time skin diffuse reflectance spectroscopy measurement system was designed based on a micro-spectrometer.Digitonin-horseradish peroxidase copolymer solution was prepared.According to the properties digitonin binds to the hydroxy of cholesterol molecular specifically and the horseradish peroxidase reacts with TMB color solution (the main component is 3,3’,5,5’-tetramethylbenzidine )a color change was produced,by which the skin cholesterol was identified and instructed with high sensitivity and high specificity,and the concentration of skin cholesterol was quantified by measuring the degree of color change.In order to validate the feasibility of this

  6. Multiparametric MRI for prostate cancer detection: Preliminary results on quantitative analysis of dynamic contrast enhanced imaging, diffusion-weighted imaging and spectroscopy imaging.

    Science.gov (United States)

    Fusco, Roberta; Sansone, Mario; Petrillo, Mario; Setola, Sergio Venanzio; Granata, Vincenza; Botti, Gerardo; Perdonà, Sisto; Borzillo, Valentina; Muto, Paolo; Petrillo, Antonella

    2016-09-01

    Early promising data suggest that combined use of both morphological and functional MRI (multi-parametric MR, mpMRI) including MRSI, DWI and DCE may be of additional value for prostate cancer localization and its local staging. The objective of this paper is to evaluate the diagnostic performance of mpMRI in the detection of prostate cancer. Thirty-one consecutive male patients were screened to be enrolled in a single center prospective observational study. All eligible patients underwent multi-parametric MRI and TRUS (Trans Rectal Ultra Sound) guided prostate biopsies. A register, approved by the Institutional Ethics Committee, included patients enrolled in this study. All patients who decided to undergo the MRI examination signed an explicit informed consensus. MRI data were aligned on a common spatial grid and several functional parameters (perfusion, diffusion and metabolic parameters) were computed. Statistical analysis was conducted in order to compare mpMRI with biopsy-based analysis. Statistically significant differences between median values in high Gleason score (≥5) and low Gleason score (<5) to Wilcox on rank sum test were obtained for MRSI parameters and for plasma fraction (Tofts model) of DCE-MRI. The area under curve obtained with ROC analysis showed that the best-performing single-parameter was vp (plasma fraction of Tofts model), while the best parameters combination to discriminate the area with high Gleason score were (Cho+Cr)/Cit and Cho+Cr. Linear Discrimination Analysis showed that the best results were obtained considering the linear combination of all MRSI parameters and the linear combination of all features (perfusion, diffusion and metabolic parameters). In conclusion, our findings showed that by combining morphological MRI, DWI, DCE-MRI and MRSI, an increase in sensitivity and specificity correlated to biopsy Gleason grade could be obtained. Furthermore, morphological and functional MRI could have a diagnostic role in patients with

  7. Quantification and parametrization of non-linearity effects by higher-order sensitivity terms in scattered light differential optical absorption spectroscopy

    Science.gov (United States)

    Puķīte, Jānis; Wagner, Thomas

    2016-05-01

    We address the application of differential optical absorption spectroscopy (DOAS) of scattered light observations in the presence of strong absorbers (in particular ozone), for which the absorption optical depth is a non-linear function of the trace gas concentration. This is the case because Beer-Lambert law generally does not hold for scattered light measurements due to many light paths contributing to the measurement. While in many cases linear approximation can be made, for scenarios with strong absorptions non-linear effects cannot always be neglected. This is especially the case for observation geometries, for which the light contributing to the measurement is crossing the atmosphere under spatially well-separated paths differing strongly in length and location, like in limb geometry. In these cases, often full retrieval algorithms are applied to address the non-linearities, requiring iterative forward modelling of absorption spectra involving time-consuming wavelength-by-wavelength radiative transfer modelling. In this study, we propose to describe the non-linear effects by additional sensitivity parameters that can be used e.g. to build up a lookup table. Together with widely used box air mass factors (effective light paths) describing the linear response to the increase in the trace gas amount, the higher-order sensitivity parameters eliminate the need for repeating the radiative transfer modelling when modifying the absorption scenario even in the presence of a strong absorption background. While the higher-order absorption structures can be described as separate fit parameters in the spectral analysis (so-called DOAS fit), in practice their quantitative evaluation requires good measurement quality (typically better than that available from current measurements). Therefore, we introduce an iterative retrieval algorithm correcting for the higher-order absorption structures not yet considered in the DOAS fit as well as the absorption dependence on

  8. Study by neutron diffusion of local order liquid sulfur around the polymerization transition; Etude par diffusion de neutrons de l`ordre local du soufre liquide autour de la transition de polymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Descotes, L.

    1994-05-01

    We studied the liquid sulfur according to the temperature. The sulfur is one of the most complicated elementary liquid. We experimented the neutron diffusion by the powder orthorhombic sulfur. The complexity at the polymerization transition are only accompanied by weak local structural transfer. 231 refs., 48 figs., 8 tabs., 3 annexes.

  9. A short-range ordering in soft magnetic Fe-based metallic glasses studied by Mössbauer spectroscopy and Reverse Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Babilas, Rafał, E-mail: rafal.babilas@polsl.pl [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego St. 18a, 44-100 Gliwice (Poland); Mariola, Kądziołka-Gaweł [August Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4 St., 40-007 Katowice (Poland); Burian, Andrzej [August Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4 St., 40-007 Katowice (Poland); Silesian Center of Education and Interdisciplinary Research, 75 Pułku Piechoty St., 40-500 Chorzów (Poland); Temleitner, László [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest (Hungary)

    2016-05-15

    Selected soft magnetic amorphous alloys Fe{sub 80}B{sub 20}, Fe{sub 70}Nb{sub 10}B{sub 20} and Fe{sub 62}Nb{sub 8}B{sub 30} were produced by the melt-spinning and characterized by X-ray diffraction (XRD), transmission Mössbauer spectroscopy (MS), Reverse Monte Carlo modeling (RMC) and relative magnetic permeability measurements. The Mössbauer spectroscopy allowed to study the local environments of the Fe-centered atoms in the amorphous structure of binary and ternary glassy alloys. The MS provided also information about the changes in the amorphous structure due to the modification of chemical composition by various boron and niobium content. The RMC simulation based on the structure factors determined by synchrotron XRD measurements was also used in modeling of the atomic arrangements and short-range order in Fe-based model alloys. Addition of boron and niobium in the ternary model alloys affected the disorder in as-cast state and also influenced on the number of nearest neighbor Fe–Fe atoms, consequently. The distributions of Fe- and B-centered coordination numbers showed that N=10, 9 and 8 are dominated around Fe atoms and N=9, 8 and 7 had the largest population around B atoms in the examined amorphous alloys. Moreover, the relationship between the content of the alloying elements, the local atomic ordering and the magnetic permeability (magnetic after-effects) was mentioned. - Highlights: • SRO was investigated by XRD, Mössbauer, RMC and magnetic measurements. • N=10,9,8 are dominated around Fe atoms for Fe{sub 80}B{sub 20}, Fe{sub 70}Nb{sub 10}B{sub 20} and Fe{sub 62}Nb{sub 8}B{sub 30}. • N=9, 8 and 7 had the largest population around B atoms. • Fe-centered clusters with N=12 indicating icosahedral atomic configurations. • Magnetic after-effects is sensitive to the SRO and concentration of free volume.

  10. Diffusion of insoluble carbon in zirconium oxides

    CERN Document Server

    Vykhodets, V B; Koester, U; Kondrat'ev, V V; Kesarev, A G; Hulsen, C; Kurennykh, T E

    2011-01-01

    The diffusion coefficient of insoluble carbon in zirconium oxides has been obtained for the temperature range of 900-1000A degrees C. There are no published data on the diffusion of insoluble impurities; these data are of current interest for the diffusion theory and nuclear technologies. Tracer atoms 13C have been introduced into oxides by means of ion implantation and the kinetics of their emission from the samples in the process of annealing in air has been analyzed. The measurements have been performed using the methods of nuclear microanalysis and X-ray photoelectron spectroscopy. The diffusion activation energy is 2.7 eV and the carbon diffusion coefficient is about six orders of magnitude smaller than that for oxygen self-diffusion in the same systems. This result indicates the strong anomaly of the diffusion properties of carbon in oxides. As a result, zirconium oxides cannot be used in some nuclear technologies, in particular, as a material of sources for accelerators of short-lived carbon isotopes.

  11. A Novel Implement Scheme of Diffusion Sensitive Gradient Magnetic Field for Magnetic Resonance Diffusion Weighted Spectroscopy%一种新的用于磁共振扩散加权波谱术的扩散敏感梯度磁场施加方案

    Institute of Scientific and Technical Information of China (English)

    张怀岑; 王翔; 高嵩

    2011-01-01

    目的 提出一种基于PRESS的用于磁共振扩散加权波谱的扩散敏感梯度磁场施加方案.方法 在PRESS序列中的2个π射频脉冲两侧各施加一对交错的扩散敏感梯度磁场.结果 本方案有效减小涡流,利用PRESS序列中2个π射频脉冲之间的时间,延长了扩散梯度磁场脉冲的持续时间.即使在扩散权重较大的情况下,Naa,Cr及Cho的峰仍十分清晰,信噪比满足进一步分析的需要.结论 利用这一方案可以在常规医用磁共振成像设备上实现扩散加权波谱(DWS).%Objective To propose a new diffusion sensitive gradient magnetic field implement scheme basing on point resolved spectroscopy(PRESS) for magnetic resonance diffusion weighted spectroscopy. Methods Two pairs of interleaving pulsed gradient magnetic fields were applied symmetrically around the two π RF pulse in PRESS sequence respectively. Results Through the proposed scheme, the induced eddy currents were minimized, the interval time between the two π RF pulses in PRESS sequence was utilized effectively and the duration time of diffusion sensitive gradient magnetic pulses was increased. Conclusion It is feasible to implement diffusion weighted spectroscopy(DWS) in conventional clinical MRI scanners with this scheme.

  12. Mg diffusion in K(Ta{sub 0.65}Nb{sub 0.35})O{sub 3} thin films grown on MgO evidenced by Auger electron spectroscopy investigation

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Q.; Bouquet, V.; Demange, V.; Deputier, S. [Sciences Chimiques de Rennes, UMR 6226 CNRS/Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France); Universite Europeenne de Bretagne (France); Wyczisk, F.; Garry, G.; Ziaie, A. [Thales Research and Technology, rd. 128, 91767 Palaiseau Cedex (France); Guilloux-Viry, M., E-mail: maryline.guilloux-viry@univ-rennes1.fr [Sciences Chimiques de Rennes, UMR 6226 CNRS/Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France); Universite Europeenne de Bretagne (France)

    2011-09-01

    The diffusion of Mg in pulsed laser deposited K(Ta{sub 0.65}Nb{sub 0.35})O{sub 3} thin films epitaxially grown on (1 0 0) MgO single crystal substrate were investigated by Auger electron spectroscopy (AES). A diffusion of Mg from the substrate into the whole thickness (400 nm) of the as-deposited K(Ta{sub 0.65}Nb{sub 0.35})O{sub 3} films was observed with an accumulation of Mg at the surface. Ex situ post-annealing (750 deg. C/2 h) has led to a homogeneous distribution of Mg in all the ferroelectric coating. This strong reaction between film and substrate promotes a doping effect, responsible for the reduction of K(Ta{sub 0.65}Nb{sub 0.35})O{sub 3} dielectric losses in comparison with films grown on other substrates.

  13. Use of diffusion-ordered NMR spectroscopy and HPLC-UV-SPE-NMR to identify undeclared synthetic drugs in medicines illegally sold as phytotherapies.

    Science.gov (United States)

    Silva, Lorena M A; Filho, Elenilson G A; Thomasi, Sérgio S; Silva, Bianca F; Ferreira, Antonio G; Venâncio, Tiago

    2013-09-01

    The informal (and/or illegal) e-commerce of pharmaceutical formulations causes problems that governmental health agencies find hard to control, one of which concerns formulas sold as natural products. The purpose of this work was to explore the advantages and limitations of DOSY and HPLC-UV-SPE-NMR. These techniques were used to identify the components of a formula illegally marketed in Brazil as an herbal medicine possessing anti-inflammatory and analgesic properties. DOSY was able to detect the major components present at higher concentrations. Complete characterization was achieved using HPLC-UV-SPE-NMR, and 1D and 2D NMR analyses enabled the identification of known synthetic drugs. These were ranitidine and a mixture of orphenadrine citrate, piroxicam, and dexamethasone, which are co-formulated in a remedy called Rheumazim that is used to relieve severe pain, but it is prohibited in Brazil because of a lack of sufficient pharmacokinetic and pharmacodynamic information. Copyright © 2013 John Wiley & Sons, Ltd.

  14. A comparative study on the effect of Curcumin and Chlorin-p6 on the diffusion of two organic cations across a negatively charged lipid bilayer probed by second harmonic spectroscopy

    Science.gov (United States)

    Saini, R. K.; Varshney, G. K.; Dube, A.; Gupta, P. K.; Das, K.

    2014-09-01

    The influence of Curcumin and Chlorin-p6 (Cp6) on the real time diffusion kinetics of two organic cations, LDS (LDS-698) and Malachite Green (MG) across a negatively charged phospholipid bilayer is investigated by Second Harmonic (SH) spectroscopy. The diffusion time constant of LDS at neutral pH in liposomes containing either Curcumin or Cp6 is significantly reduced, the effect being more pronounced with Curcumin. At acidic pH, the quantum of reduction in the diffusion time constant of MG by both the drugs was observed to be similar. The relative changes in the average diffusion time constants of the cations with increasing drug concentration at pH 5.0 and 7.4 shows a substantial pH effect for Curcumin induced membrane permeability, while a modest pH effect was observed for Cp6 induced membrane permeability. Based on available evidence this can be attributed to the increased interaction between the drug and the polar head groups of the lipid at pH 7.4 where the drug resides closer to the lipid-water interface.

  15. In situ study of mass transfer in aqueous solutions under high pressures via Raman