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Sample records for spinning spectroscopic technique

  1. Spectroscopic studies of UV irradiated erythrosine B thin films prepared by spin coating technique

    NASA Astrophysics Data System (ADS)

    Zeyada, H. M.; El-Mallah, H. M.; Atwee, T.; El-Damhogi, D. G.

    2017-05-01

    The spectroscopic studies of erythrosine B thin films manufactured by the spin coating technique have been presented. The spectra of infrared absorption allow characterization of vibrational modes for erythrosine B in powder form, pristine and UV irradiated thin films. The absorption spectra recorded in UV-vis-NIR for pristine films of erythrosine B display two main bands. UV irradiation on erythrosine B films decreased absorbance over the spectra. Indirect allowed transition with optical energy gap of 2.57 eV is observed in pristine films. UV irradiation introduced structural defects and decreased optical band gap. Some of the optical absorption parameters and their relation to UV irradiation times, namely molar extinction coefficient (ε), electronic dipole strength (q2), and oscillator strength (f), of the principal optical transitions have also been evaluated.

  2. Spectroscopic studies of UV irradiated erythrosine B thin films prepared by spin coating technique.

    PubMed

    Zeyada, H M; El-Mallah, H M; Atwee, T; El-Damhogi, D G

    2017-05-15

    The spectroscopic studies of erythrosine B thin films manufactured by the spin coating technique have been presented. The spectra of infrared absorption allow characterization of vibrational modes for erythrosine B in powder form, pristine and UV irradiated thin films. The absorption spectra recorded in UV-vis-NIR for pristine films of erythrosine B display two main bands. UV irradiation on erythrosine B films decreased absorbance over the spectra. Indirect allowed transition with optical energy gap of 2.57eV is observed in pristine films. UV irradiation introduced structural defects and decreased optical band gap. Some of the optical absorption parameters and their relation to UV irradiation times, namely molar extinction coefficient (ε), electronic dipole strength (q(2)), and oscillator strength (f), of the principal optical transitions have also been evaluated. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. A Comparison of Galaxy Counting Techniques in Spectroscopically Undersampled Regions

    NASA Astrophysics Data System (ADS)

    Specian, Mike A.; Szalay, Alex S.

    2016-11-01

    Accurate measures of galactic overdensities are invaluable for precision cosmology. Obtaining these measurements is complicated when members of one’s galaxy sample lack radial depths, most commonly derived via spectroscopic redshifts. In this paper, we utilize the Sloan Digital Sky Survey’s Main Galaxy Sample to compare seven methods of counting galaxies in cells when many of those galaxies lack redshifts. These methods fall into three categories: assigning galaxies discrete redshifts, scaling the numbers counted using regions’ spectroscopic completeness properties, and employing probabilistic techniques. We split spectroscopically undersampled regions into three types—those inside the spectroscopic footprint, those outside but adjacent to it, and those distant from it. Through Monte Carlo simulations, we demonstrate that the preferred counting techniques are a function of region type, cell size, and redshift. We conclude by reporting optimal counting strategies under a variety of conditions.

  4. Spectroscopic Measurement Techniques for Aerospace Flows

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Bathel, Brett F.; Johansen, Craig T.; Cutler, Andrew D.; Hurley, Samantha

    2014-01-01

    The conditions that characterize aerospace flows are so varied, that a single diagnostic technique is not sufficient for its measurement. Fluid dynamists use knowledge of similarity to help categorize and focus on different flow conditions. For example, the Reynolds number represents the ratio of inertial to viscous forces in a flow. When the velocity scales, length scales, and gas density are large and the magnitude of the molecular viscosity is low, the Reynolds number becomes large. This corresponds to large scale vehicles (e.g Airbus A380), fast moving objects (e.g. artillery projectiles), vehicles in dense fluids (e.g. submarine in water), or flows with low dynamic viscosity (e.g. skydiver in air). In each of these cases, the inertial forces dominate viscous forces, and unsteady turbulent fluctuations in the flow variables are observed. In contrast, flows with small length scales (e.g. dispersion of micro-particles in a solid rocket nozzle), slow moving objects (e.g. micro aerial vehicles), flows with low density gases (e.g. atmospheric re-entry), or fluids with a large magnitude of viscosity (e.g. engine coolant flow), all have low Reynolds numbers. In these cases, viscous forces become very important and often the flows can be steady and laminar. The Mach number, which is the ratio of the velocity to the speed of sound in the medium, also helps to differentiate types of flows. At very low Mach numbers, acoustic waves travel much faster than the object, and the flow can be assumed to be incompressible (e.g. Cessna 172 aircraft). As the object speed approaches the speed of sound, the gas density can become variable (e.g. flow over wing of Learjet 85). When the object speed is higher than the speed of sound (Ma > 1), the presences of shock waves and other gas dynamic features can become important to the vehicle performance (e.g. SR-71 Blackbird). In the hypersonic flow regime (Ma > 5), large changes in temperature begin to affect flow properties, causing real

  5. Evaluation of Her2 status using photoacoustic spectroscopic CT techniques

    NASA Astrophysics Data System (ADS)

    Shaffer, Michael; Kruger, Robert; Reinecke, Daniel; Chin-Sinex, Helen; Mendonca, Marc; Stantz, Keith M.

    2010-02-01

    Purpose: The purpose of this study is to determine the feasibility of using photacoustic CT spectroscopy(PCT-s) to track a near infrared dye conjugated with trastuzumab in vivo. Materials and Methods: An animal model was developed which contained both high and low Her2 expression tumor xenografts on the same mouse. The tumors were imaged at multiple wavelengths (680- 950nm) in the PCT scanner one day prior to injection of the near infrared conjugated probe. Baseline optical imaging data was acquired and the probe was then injected via the tail vein. Fluorescence data was acquired over the next week, PCT spectroscopic data was also acquired during this timeframe. The mice were sacrificed and tumors were extirpated and sent to pathology for IHC staining to verify Her2 expression levels. The optical fluorescence images were analyzed to determine probe uptake dynamics. Reconstructed PCT spectroscopic data was analyzed using IDL routines to deconvolve the probe signal from endogenous background signals, and to determine oxygen saturation. Results: The location of the NIR conjugate was able to be identified within the tumor utilizing IDL fitting routines, in addition oxygen saturation, and hemoglobin concentrations were discernible from the spectroscopic data. Conclusion: Photacoustic spectroscopy allows for the determination of in vivo tumor drug delivery at greater depths than can be determined from optical imaging techniques.

  6. Synthesis and spectroscopic characterization of high-spin mononuclear iron(II) p-semiquinonate complexes.

    PubMed

    Baum, Amanda E; Park, Heaweon; Lindeman, Sergey V; Fiedler, Adam T

    2014-12-01

    Two mononuclear iron(II) p-semiquinonate (pSQ) complexes have been generated via one-electron reduction of precursor complexes containing a substituted 1,4-naphthoquinone ligand. Detailed spectroscopic and computational analysis confirmed the presence of a coordinated pSQ radical ferromagnetically coupled to the high-spin Fe(II) center. The complexes are intended to model electronic interactions between (semi)quinone and iron cofactors in biology.

  7. Application of optical spectroscopic techniques for disease diagnosis

    NASA Astrophysics Data System (ADS)

    Saha, Anushree

    Optical spectroscopy, a truly non-invasive tool for remote diagnostics, is capable of providing valuable information on the structure and function of molecules. However, most spectroscopic techniques suffer from drawbacks, which limit their application. As a part of my dissertation work, I have developed theoretical and experimental methods to address the above mentioned issues. I have successfully applied these methods for monitoring the physical, chemical and biochemical parameters of biomolecules involved in some specific life threatening diseases like lead poisoning and age-related macular degeneration (AMD). I presented optical studies of melanosomes, which are one of the vital organelles in the human eye, also known to be responsible for a disease called age-related macular degeneration (AMD), a condition of advanced degeneration which causes progressive blindness. I used Raman spectroscopy, to first chemically identify the composition of melanosome, and then monitor the changes in its functional and chemical behavior due to long term exposure to visible light. The above study, apart from explaining the role of melanosomes in AMD, also sets the threshold power for lasers used in surgeries and other clinical applications. In the second part of my dissertation, a battery of spectroscopic techniques was successfully applied to explore the different binding sites of lead ions with the most abundant carrier protein molecule in our circulatory system, human serum albumin. I applied optical spectroscopic tools for ultrasensitive detection of heavy metal ions in solution which can also be used for lead detection at a very early stage of lead poisoning. Apart from this, I used Raman microspectroscopy to study the chemical alteration occurring inside a prostate cancer cell as a result of a treatment with a low concentrated aqueous extract of a prospective drug, Nerium Oleander. The experimental methods used in this study has tremendous potential for clinical

  8. Electron spin resonance spectroscopic studies of radical cation reactions

    SciTech Connect

    Dai, S.

    1990-01-01

    A spin Hamiltonian suitable for theoretical analyses of ESR spectra is derived using the general effective Hamiltonian theory in the usual Schroedinger representation. The Permutation Indices method is extended to obtain the dynamic exchange equations used in ESR lineshape simulation. The correlation between [beta]-hydrogen coupling constants and their geometric orientations are derived using a perturbation method. The three electron bond model is extended to rationalize unimolecular rearrangements of radical cations. The ring-closed radical cations of 9,10-octalin oxide and synsesquinorbornene oxide have been characterized by ESR spectroscopy in the CFCl[sub 3] matrix at low temperature. The self-electron-transfer rate constants between the methyl viologen dication and cation have been determined by dynamic ESR lineshape simulations at room temperature in allyl alcohol, water, methanol and propargyl alcohol solvents. The radical cation formed by the radiolytic oxidation of allylamine in Freon matrices at 77 K is the 3-iminiopropyl distonic species(3-iminium-1-propyl radical). The nucleophilic endocylization of the but-3-en-1-ol radical cation to the protonated tetrahydrofuran-3-yl radical was observed in the radiolytic oxidation of but-3-en-1-ol in Freon matrices. ESR studies of the radiolytic oxidation of 1,5-hexdiyne have resulted in characterization the 1,5-hexadiyne radical cation isomerizing to the 1,2,4,5-hexatetraene radical cation. The symmetric (C[sub 2v]) bicyclo[3.3.0]-octa-2,6-diene-4,8-diyl(a bridged 1,4-bishomobenzene species) radical cation is produced by the radiolytic oxidation of semibullvalene in Freon matrices. The ring-opening 3,4-dimethylenecyclobutene radical cation to 1,2,4,5-hexatetraene radical cation was observed in the photolysis of 3,4-dimethylenecyclobutene radical cation. The cyclooctatetraene radical cation generated by radiolytic oxidation photoisomerizes to bicyclo[3.3.0]octa-2,6-diene-4,8-diyl radical cation.

  9. Vibration/Acoustic Isolation Techniques for spectroscopic mapping STS

    NASA Astrophysics Data System (ADS)

    Alldredge, Jacob; Hoskinson, Emile; Hoffmann, Joan; Harrd, Thomas; Packard, Richard; Davis, J. C.

    2004-03-01

    Previous studies of spectroscopic mapping STS systems indicate that the coupling of mechanical, acoustic, and electrical building noise to experiments can be the limiting noise factor when making measurements. With this in mind we have set out to construct new labs that reduce or eliminate noise from the building. Here we describe the design considerations and techniques used in the construction of new, extremely low vibration lab space, to be used initially for scanning tunneling spectroscopy experiments. The lab space is decoupled from the building by placing it upon 25 ton inertial blocks (30 tons including sound room and equipment) resting on air springs. The experimental apparatus itself rests on another set of air springs. The entire space is surrounded by two nested acoustic rooms. We report on the degree of isolation achieved by these techniques.

  10. New Developments of Broadband Cavity Enhanced Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Walsh, A.; Zhao, D.; Linnartz, H.; Ubachs, W.

    2013-06-01

    In recent years, cavity enhanced spectroscopic techniques, such as cavity ring-down spectroscopy (CRDS), cavity enhanced absorption spectroscopy (CEAS), and broadband cavity enhanced absorption spectroscopy (BBCEAS), have been widely employed as ultra-sensitive methods for the measurement of weak absorptions and in the real-time detection of trace species. In this contribution, we introduce two new cavity enhanced spectroscopic concepts: a) Optomechanical shutter modulated BBCEAS, a variant of BBCEAS capable of measuring optical absorption in pulsed systems with typically low duty cycles. In conventional BBCEAS applications, the latter substantially reduces the signal-to-noise ratio (S/N), consequently also reducing the detection sensitivity. To overcome this, we incorporate a fast optomechanical shutter as a time gate, modulating the detection scheme of BBCEAS and increasing the effective duty cycle reaches a value close to unity. This extends the applications of BBCEAS into pulsed samples and also in time-resolved studies. b) Cavity enhanced self-absorption spectroscopy (CESAS), a new spectroscopic concept capable of studying light emitting matter (plasma, flames, combustion samples) simultaneously in absorption and emission. In CESAS, a sample (plasma, flame or combustion source) is located in an optically stable cavity consisting of two high reflectivity mirrors, and here it acts both as light source and absorbing medium. A high detection sensitivity of weak absorption is reached without the need of an external light source, such as a laser or broadband lamp. The performance is illustrated by the first CESAS result on a supersonically expanding hydrocarbon plasma. We expect CESAS to become a generally applicable analytical tool for real time and in situ diagnostics. A. Walsh, D. Zhao, W. Ubachs, H. Linnartz, J. Phys. Chem. A, {dx.doi.org/10.1021/jp310392n}, in press, 2013. A. Walsh, D. Zhao, H. Linnartz Rev. Sci. Instrum. {84}(2), 021608 2013. A. Walsh, D. Zhao

  11. Rapid identification of single microbes by various Raman spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Rösch, Petra; Harz, Michaela; Schmitt, Michael; Peschke, Klaus-Dieter; Ronneberger, Olaf; Burkhardt, Hans; Motzkus, Hans-Walter; Lankers, Markus; Hofer, Stefan; Thiele, Hans; Popp, Jürgen

    2006-02-01

    A fast and unambiguous identification of microorganisms is necessary not only for medical purposes but also in technical processes such as the production of pharmaceuticals. Conventional microbiological identification methods are based on the morphology and the ability of microbes to grow under different conditions on various cultivation media depending on their biochemical properties. These methods require pure cultures which need cultivation of at least 6 h but normally much longer. Recently also additional methods to identify bacteria are established e.g. mass spectroscopy, polymerase chain reaction (PCR), flow cytometry or fluorescence spectroscopy. Alternative approaches for the identification of microorganisms are vibrational spectroscopic techniques. With Raman spectroscopy a spectroscopic fingerprint of the microorganisms can be achieved. Using UV-resonance Raman spectroscopy (UVRR) macromolecules like DNA/RNA and proteins are resonantly enhanced. With an excitation wavelength of e.g. 244 nm it is possible to determine the ratio of guanine/cytosine to all DNA bases which allows a genotypic identification of microorganisms. The application of UVRR requires a large amount of microorganisms (> 10 6 cells) e.g. at least a micro colony. For the analysis of single cells micro-Raman spectroscopy with an excitation wavelength of 532 nm can be used. Here, the obtained information is from all type of molecules inside the cells which lead to a chemotaxonomic identification. In this contribution we show how wavelength dependent Raman spectroscopy yields significant molecular information applicable for the identification of microorganisms on a single cell level.

  12. Magnetic resonance spectroscopy editing techniques of coupled spin systems at high field

    NASA Astrophysics Data System (ADS)

    Snyder, Jeff

    Magnetic resonance spectroscopy (MRS) provides a non-invasive tool for investigating chemical concentrations in the human brain. The detection of metabolites is useful in understanding functional pathways in healthy and diseased states. Many important metabolites are composed of multiple interacting spins coupled through chemical bonds in the molecule. Whereas the observation of strong uncoupled (singlet) resonances is straightforward, complex coupling patterns and signal overlap often hinder the detection of coupled spin systems, rendering quantification problematic. One of the primary goals of this project is to investigate spectral editing techniques to detect coupled spin systems and provide a means for increasing the accuracy of quantification. A new method of spectral editing based on subtraction spectroscopy is proposed, which relies on signal differences at constant echo time (TE) produced by varying the inter-pulse delays in an asymmetric PRESS sequence. The method requires no spectrally selective pulses or multiple quantum filters, and can be easily implemented with a standard PRESS sequence. All non-varying spectral information is maintained, in contrast to other popular editing techniques. In terms of strongly coupled spin systems, the procedure is demonstrated for glutamate and glutamine discrimination, as well as simulated optimization of field strength for detection of several strongly coupled metabolites. To produce the necessary TE space variations for weakly coupled systems, the flip angle of the second refocusing pulse was varied. This technique was applied for the detection of gamma-aminobutyric acid, which is completely obscured at standard clinical field strengths. A second editing method investigated the optimization of PRESS timing parameters at multiple field strengths for the simultaneous detection of glutamate and glutamine in vivo, by maximizing the signal yield and minimizing the significant overlap at lower field strengths. Finally

  13. The VLT-FLAMES Tarantula Survey. XXI. Stellar spin rates of O-type spectroscopic binaries

    NASA Astrophysics Data System (ADS)

    Ramírez-Agudelo, O. H.; Sana, H.; de Mink, S. E.; Hénault-Brunet, V.; de Koter, A.; Langer, N.; Tramper, F.; Gräfener, G.; Evans, C. J.; Vink, J. S.; Dufton, P. L.; Taylor, W. D.

    2015-08-01

    Context. The initial distribution of spin rates of massive stars is a fingerprint of their elusive formation process. It also sets a key initial condition for stellar evolution and is thus an important ingredient in stellar population synthesis. So far, most studies have focused on single stars. Most O stars are, however, found in multiple systems. Aims: By establishing the spin-rate distribution of a sizeable sample of O-type spectroscopic binaries and by comparing the distributions of binary subpopulations with one another and with that of presumed-single stars in the same region, we aim to constrain the initial spin distribution of O stars in binaries, and to identify signatures of the physical mechanisms that affect the evolution of the spin rates of massive stars. Methods: We use ground-based optical spectroscopy obtained in the framework of the VLT-FLAMES Tarantula Survey (VFTS) to establish the projected equatorial rotational velocities (νesini) for components of 114 spectroscopic binaries in 30 Doradus. The νesini values are derived from the full width at half maximum (FWHM) of a set of spectral lines, using a FWHM vs. νesini calibration that we derive based on previous line analysis methods applied to single O-type stars in the VFTS sample. Results: The overall νesini distribution of the primary stars resembles that of single O-type stars in the VFTS, featuring a low-velocity peak (at νesini< 200 kms-1) and a shoulder at intermediate velocities (200 < νesini< 300 kms-1). The distributions of binaries and single stars, however, differ in two ways. First, the main peak at νesini ~ 100kms-1 is broader and slightly shifted towards higher spin rates in the binary distribution than that of the presumed-single stars. This shift is mostly due to short-period binaries (Porb~< 10 d). Second, the νesini distribution of primaries lacks a significant population of stars spinning faster than 300 kms-1, while such a population is clearly present in the single

  14. Raman spectroscopic study of the frustrated spin 1/2 antiferromagnet clinoatacamite

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Dong; Zheng, Xu-Guang; Meng, Dong-Dong; Xu, Xing-Liang; Guo, Qi-Xin

    2013-06-01

    Raman spectroscopy is a valuable and complementary tool for studying geometrically frustrated magnetic systems due to the intrinsic spin-phonon coupling. Here, we report on a Raman spectroscopic study of the geometrically frustrated spin 1/2 antiferromagnet microcrystalline clinoatacamite Cu2(OH)3Cl, focusing on the anomalous transition into the intermediate phase at Tc1 = 18.1 K. By measuring the temperature-dependent (295-4 K) full spectral profiles and main representative modes in spectral regions from 4000 to 95 cm-1, we observed probable signatures of successive magnetic transitions near Tc1 = 18 K and Tc2 = 6.4 K in the Raman band frequencies and peak widths of the representative modes. Further, we observed a pronounced Raman spectroscopy background featuring a broad continuum at all temperatures. A quantitative analysis reveals that spin fluctuations may exist on a picosecond time scale in the intermediate phase. The short time scale falls out of the μSR time window; therefore, in the intermediate phase, the μSR study as reported in (2005 Phys. Rev. Lett. 95 057201) apparently only probed the local field of the ordered spins but overlooked the quickly fluctuating ones. This is likely to give a reasonable explanation of the fact that only a small entropy release occurs at Tc1 = 18 K although a long-range order is formed.

  15. Terahertz imaging of metastatic lymph nodes using spectroscopic integration technique

    PubMed Central

    Park, Jae Yeon; Choi, Hyuck Jae; Cheon, Hwayeong; Cho, Seong Whi; Lee, Seungkoo; Son, Joo-Hiuk

    2017-01-01

    Terahertz (THz) imaging was used to differentiate the metastatic states of frozen lymph nodes (LNs) by using spectroscopic integration technique (SIT). The metastatic states were classified into three groups: healthy LNs, completely metastatic LNs, and partially metastatic LNs, which were obtained from three mice without infection and six mice infected with murine melanoma cells for 30 days and 15 days, respectively. Under histological examination, the healthy LNs and completely metastatic LNs were found to have a homogeneous cellular structure but the partially metastatic LNs had interfaces of the melanoma and healthy tissue. THz signals between the experimental groups were not distinguished at room temperature due to high attenuation by water in the tissues. However, a signal gap between the healthy and completely metastatic LNs was detected at freezing temperature. The signal gap could be enhanced by using SIT that is a signal processing method dichotomizing the signal difference between the healthy cells and melanoma cells with their normalized spectral integration. This technique clearly imaged the interfaces in the partially metastatic LNs, which could not be achieved by existing methods using a peak point or spectral value. The image resolution was high enough to recognize a metastatic area of about 0.7 mm size in the partially metastatic LNs. Therefore, this pilot study demonstrated that THz imaging of the frozen specimen using SIT can be used to diagnose the metastatic state of LNs for clinical application. PMID:28271007

  16. Time-resolved infrared spectroscopic techniques as applied to channelrhodopsin

    PubMed Central

    Ritter, Eglof; Puskar, Ljiljana; Bartl, Franz J.; Aziz, Emad F.; Hegemann, Peter; Schade, Ulrich

    2015-01-01

    Among optogenetic tools, channelrhodopsins, the light gated ion channels of the plasma membrane from green algae, play the most important role. Properties like channel selectivity, timing parameters or color can be influenced by the exchange of selected amino acids. Although widely used, in the field of neurosciences for example, there is still little known about their photocycles and the mechanism of ion channel gating and conductance. One of the preferred methods for these studies is infrared spectroscopy since it allows observation of proteins and their function at a molecular level and in near-native environment. The absorption of a photon in channelrhodopsin leads to retinal isomerization within femtoseconds, the conductive states are reached in the microsecond time scale and the return into the fully dark-adapted state may take more than minutes. To be able to cover all these time regimes, a range of different spectroscopical approaches are necessary. This mini-review focuses on time-resolved applications of the infrared technique to study channelrhodopsins and other light triggered proteins. We will discuss the approaches with respect to their suitability to the investigation of channelrhodopsin and related proteins. PMID:26217670

  17. Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes

    DOE PAGES

    Bucinsky, Lukas; Breza, Martin; Lee, Wei-Tsung; ...

    2017-04-05

    High-oxidation state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin state preferences of three-fold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(ImR)3}FeN], R = tBu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(ImR)3}Fe(NR')]+, R = Mes, R' = Ad (1- adamantyl, 3), tBu (4), have been investigated by electronic absorption and Mössbauer effect spectroscopies.more » For comparison, two other Fe(IV) nitrido complexes, [(TIMENAr)FeN]+, (TIMENAr = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), have been investigated by 57Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (HFEPR) (for 3 and 4) and frequency-domain Fouriertransform (FD-FT) THz EPR (for 3), which reveal their zero-field splitting (zfs) parameters. Experimentally correlated theoretical studies comprising ligand-field theory (LFT) and quantum chemical theory (QCT), the latter including both density functional theory (DFT) and ab initio methods reveal the key role played by the Fe3dz2 (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin state preference of the complex. Lastly, the ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.« less

  18. Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes.

    PubMed

    Bucinsky, Lukas; Breza, Martin; Lee, Wei-Tsung; Hickey, Anne K; Dickie, Diane A; Nieto, Ismael; DeGayner, Jordan A; Harris, T David; Meyer, Karsten; Krzystek, J; Ozarowski, Andrew; Nehrkorn, Joscha; Schnegg, Alexander; Holldack, Karsten; Herber, Rolfe H; Telser, Joshua; Smith, Jeremy M

    2017-04-05

    High-oxidation-state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin-state preferences of threefold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(Im(R))3}FeN], R = (t)Bu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(Im(R))3}Fe(NR')](+), R = Mes, R' = 1-adamantyl (3), (t)Bu (4), were investigated by electronic absorption and Mössbauer effect spectroscopies. For comparison, two other Fe(IV) nitrido complexes, [(TIMEN(Ar))FeN](+) (TIMEN(Ar) = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), were investigated by (57)Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (for 3 and 4) and frequency-domain Fourier-transform (FD-FT) terahertz electron paramagnetic resonance (for 3), which reveal their zero-field splitting parameters. Experimentally correlated theoretical studies comprising ligand-field theory and quantum chemical theory, the latter including both density functional theory and ab initio methods, reveal the key role played by the Fe 3dz(2) (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin-state preference of the complex. The ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.

  19. New Techniques for the Next Far Ultraviolet Spectroscopic Mission

    NASA Technical Reports Server (NTRS)

    Green, James C.; Wilkinson, Erik

    2005-01-01

    The Far Ultraviolet Spectroscopic Explorer (FUSE) has been a great success, and has addressed many critical scientific questions (Moos, et al, 2000). However, it has also highlighted the need for even more powerful instrumentation in the 900- 1200 A, regime. In particular, significantly increased effective area will permit the pursuit of additional scientific programs currently impractical or impossible with FUSE. It is unlikely that FUSE will last more than a few more years. Nor is it likely that any large scale UV-optical follow-on to HST (such as SUVO) will include the 900-1200 A, bandpass. However, FUSE remains well oversubscribed and continues to perform excellent science. Therefore, a MIDEX class mission in the next 4-6 years that could significantly improve on the FUSE capabilities would be a powerful scientific tool that would be of great utility to the astronomical community. It would open up new scientific programs if it can improve on the sensitivity of FUSE by an order of magnitude. We have identified a powerful technique for efficient, high-resolution spectroscopy in the FUV (and possibly the EUV) that may provide exactly what is needed for such a mission To achieve a factor of 10 improvement in effective area, we propose using a large (meter class), low-cost, grazing incidence metal optics. This would produced in a manner similar to the EUVE mirrors (Green, et al, 1986), using diamond turning to create the optical figure followed by uncontrolled polishing to achieve a high quality surface. This process will introduce significant figure errors that will degrade the image quality. However, if a holographic grating is employed, which has utilized the actual telescope in the recording geometry, all wavefront errors will be automatically corrected in the end-to-end spectrometer, and high quality spectroscopy will be possible with low quality (and low-cost) optics. In this way a MIDEX class FUSE can be proposed with 10 times the effective area of the

  20. Non-spin-echo 3D transverse hadamard encoded proton spectroscopic imaging in the human brain.

    PubMed

    Cohen, Ouri; Tal, Assaf; Goelman, Gadi; Gonen, Oded

    2013-07-01

    A non-spin-echo multivoxel proton MR localization method based on three-dimensional transverse Hadamard spectroscopic imaging is introduced and demonstrated in a phantom and the human brain. Spatial encoding is achieved with three selective 90° radiofrequency pulses along perpendicular axes: The first two create a longitudinal ±M(Z) Hadamard order in the volume of interest. The third pulse spatially Hadamard-encodes the ±M(Z)s in the volume of interest in the third direction while bringing them to the transverse plane to be acquired immediately. The approaching-ideal point spread function of Hadamard encoding and very short acquisition delay yield signal-to-noise-ratios of 20 ± 8, 23 ± 9, and 31 ± 10 for choline, creatine, and N-acetylaspartate in the human brain at 1.5 T from 1 cm(3) voxels in 21 min. The advantages of transverse Hadamard spectroscopic imaging are that unlike gradient (Fourier) phase-encoding: (i) the volume of interest does not need to be smaller than the field of view to prevent aliasing; (ii) the number of partitions in each direction can be small, 8, 4, or even 2 at no cost in point spread function; (iii) the volume of interest does not have to be contiguous; and (iv) the voxel profile depends on the available B1 and pulse synthesis paradigm and can, therefore, at least theoretically, approach "ideal" "1" inside and "0" elsewhere.

  1. Experimental Test of New Technique to Overcome Spin Depolarizing Resonances

    SciTech Connect

    Raymond, R. S.; Chao, A. W.; Krisch, A. D.; Leonova, M. A.; Morozov, V. S.; Sivers, D. W.; Wong, V. K.; Ganshvili, A.; Gebel, R.; Lehrach, A.; Lorentz, B.; Maier, R.; Prasuhn, D.; Stockhorst, H.; Welsch, D.; Hinterberger, F.; Kondratenko, A. M.

    2009-08-04

    We recently tested a new spin resonance crossing technique, Kondratenko Crossing (KC) by sweeping an rf solenoid's frequency through an rf-induced spin resonance with both the KC an traditional Fast Crossing (FC) patterns. Using both rf bunched and unbunched 1.85 GeV/c polarized deuterons stored in COSY, we varied the parameters of both crossing patterns. Compared to FC with the same crossing speed, KC reduced the depolarization by measured factors of 4.7+-0.3 and 19+-{sub 5}{sup 12} for unbunched and bunched beams, respectively. This clearly showed the large potential benefit of Kondratenko Crossing over Fast Crossing.

  2. Modified spin-coating technique to achieve directional colloidal crystallization.

    PubMed

    Bartlett, Andrew P; Pichumani, Moorthi; Giuliani, Maximiliano; González-Viñas, Wenceslao; Yethiraj, Anand

    2012-02-14

    Fabricating large single crystals with colloidal spheres as building blocks is challenging and of competitive interest. Spin-coating of colloids offers a robust technique, which is highly reproducible in obtaining colloidal crystals even at fast dynamical regimes; however, these crystals are intrinsically polycrystalline due to the axial symmetry of spin-coating. We report a new method that applies a nonuniform electric field during the spin-coating process. By arranging the field direction to be stationary in the rotating frame, we are able to break the axial symmetry and to orient the colloids along one predefined direction. By regulating the applied field strength, we demonstrate local control over the orientation of the crystallites, and thus, the orientation is determined by the applied field strength.

  3. Optimal and suboptimal control technique for aircraft spin recovery

    NASA Technical Reports Server (NTRS)

    Young, J. W.

    1974-01-01

    An analytic investigation has been made of procedures for effecting recovery from equilibrium spin conditions for three assumed aircraft configurations. Three approaches which utilize conventional aerodynamic controls are investigated. Included are a constant control recovery mode, optimal recoveries, and a suboptimal control logic patterned after optimal recovery results. The optimal and suboptimal techniques are shown to yield a significant improvement in recovery performance over that attained by using a constant control recovery procedure.

  4. Configuration interaction studies on the spectroscopic properties of PbO including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Wang, Luo; Rui, Li; Zhiqiang, Gai; RuiBo, Ai; Hongmin, Zhang; Xiaomei, Zhang; Bing, Yan

    2016-07-01

    Lead oxide (PbO), which plays the key roles in a range of research fields, has received a great deal of attention. Owing to the large density of electronic states and heavy atom Pb including in PbO, the excited states of the molecule have not been well studied. In this work, high level multireference configuration interaction calculations on the low-lying states of PbO have been carried out by utilizing the relativistic effective core potential. The effects of the core-valence correlation correction, the Davidson modification, and the spin-orbital coupling on the electronic structure of the PbO molecule are estimated. The potential energy curves of 18 Λ-S states correlated to the lowest dissociation limit (Pb (3Pg) + O(3Pg)) are reported. The calculated spectroscopic parameters of the electronic states below 30000 cm-1, for instance, X1Σ+, 13Σ+, and 13Σ-, and their spin-orbit coupling interaction, are compared with the experimental results, and good agreements are derived. The dipole moments of the 18 Λ-S states are computed with the configuration interaction method, and the calculated dipole moments of X1Σ+ and 13Σ+ are consistent with the previous experimental results. The transition dipole moments from 11Π, 21Π, and 21Σ+ to X1Σ+ and other singlet excited states are estimated. The radiative lifetime of several low-lying vibrational levels of 11Π, 21Π, and 21Σ+ states are evaluated. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404180 and 11574114), the Natural Science Foundation of Heilongjiang Province, China (Grant No. A2015010), the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province, China (Grant No. UNPYSCT-2015095), and the Natural Science Foundation of Jilin Province, China (Grant No. 20150101003JC).

  5. [Clinical applications of arterial spin labeling technique in brain diseases].

    PubMed

    Wang, Li; Zheng, Gang; Zhao, Tiezhu; Guo, Chao; Li, Lin; Lu, Guangming

    2013-02-01

    Arterial spin labeling (ASL) technique is a kind of perfusion functional magnetic resonance imaging method that is based on endogenous contrast, and it can measure cerebral blood flow (CBF) noninvasively. The ASL technique has advantages of noninvasiveness, simplicity and relatively lower costs so that it is more suitable for longitudinal studies compared with previous perfusion methods, such as positron emission tomography (PET), single photon emission computed tomography (SPECT), CT and the contrast agent based magnetic resonance perfusion imaging. This paper mainly discusses the current clinical applications of ASL in brain diseases as cerebrovascular diseases, brain tumors, Alzheimer's disease and epilepsy, etc.

  6. A spin-drying technique for lyopreservation of mammalian cells.

    PubMed

    Chakraborty, Nilay; Chang, Anthony; Elmoazzen, Heidi; Menze, Michael A; Hand, Steven C; Toner, Mehmet

    2011-05-01

    Stabilization of cellular material in the presence of glass-forming sugars at ambient temperatures is a viable approach that has many potential advantages over current cryogenic strategies. Experimental evidence indicates the possibility to preserve biomolecules in glassy matrices of low-molecular mobility using "glass-forming" sugars like trehalose at ambient temperatures. However, when cells are desiccated in trehalose solution using passive drying techniques, a glassy skin is formed at the liquid/vapor interface of the sample. This glassy skin prevents desiccation of the sample beyond a certain level of dryness and induces non-uniformities in the final water content. Cells trapped underneath this glassy skin may degrade due to a relatively high molecular mobility in the sample. This undesirable result underscores the need for development of a uniform, fast drying technique. In the present study, we report a new technique based on the principles of "spin drying" that can effectively address these problems. Forced convective evaporation of water along with the loss of solution due to centrifugal force leads to rapid vitrification of a thin layer of trehalose containing medium that remains on top of cells attached to the spinning glass substrate. The glassy layer produced has a consistent thickness and a small "surface-area-to-volume" ratio that minimizes any non-homogeneity. Thus, the chance of entrapping cells in a high-mobility environment decreases substantially. We compared numerical predictions to experimental observations of the drying time of 0.2-0.6 M trehalose solutions at a variety of spinning speeds ranging from 1000 to 4000 rpm. The model developed here predicts the formation of sugar films with thicknesses of 200-1000 nm, which was in good agreement with experimental results. Preliminary data suggest that after spin drying cells to about 0.159 ± 0.09 gH₂O/gdw (n = 11, ±SE), more than 95% of cells were able to preserve their membrane integrity

  7. Characterization of a laser-beam spinning technique

    SciTech Connect

    Brandon, E.

    1990-06-01

    The objective of this study was to evaluate the beam spinning technique for bridging gaps in butt joints that are CO{sub 2} laser-welded. A device was designed and built to circularly oscillate a CO{sub 2} laser beam on the plant of a work surface. A series of welds was made using a continuous-wave output power of 805 watts, and the resultant weld bead profile was characterized as a function of three process parameters. From the experimental results, predictor equations were derived for laser-beam spinning speed and amplitude of the beam spinning pattern on the work surface. The data collected in this experiment indicate that the width of the weld bead is increased by oscillating the beam and that this increase may be made without significantly reducing the weld penetration. The increased width of the weld may offer a solution to variable gaps in weld joints, which has been a recurring production problem. 13 figs., 1 tab.

  8. Investigation into Spectroscopic Techniques for Thermal Barrier Coating Spall Detection

    NASA Technical Reports Server (NTRS)

    deGroot, Wim; Opila, Beth

    2001-01-01

    Spectroscopic methods are proposed for detection of thermal barrier coating (TBC) spallation from engine hot zone components. These methods include absorption and emission of airborne marker species originally embedded in the TBC bond coat. In this study, candidate marker materials for this application were evaluated. Thermochemical analysis of candidate marker materials combined with additional constraints such as toxicity and uniqueness to engine environment, provided a short list of four potential species: platinum, copper oxide, zinc oxide. and indium. The melting point of indium was considered to be too low for serious consideration. The other three candidate marker materials, platinum, copper oxide, and zinc oxide were placed in a high temperature furnace and emission and absorption properties were measured over a temperature range from 800-1400 C and a spectral range from 250 to 18000 nm. Platinum did not provide the desired response, likely due to the low vapor Pressure of the metallic species and the low absorption of the oxide species. It was also found, however. that platinum caused a broadening of the carbon dioxide absorption at 4300 nm. The nature of this effect is not known. Absorption and emission caused by sodium and potassium impurities in the platinum were found in the platinum tests. Zinc oxide did not provide the desired response, again, most likely due to the low vapor pressure of the metallic species and the low absorption of the oxide species. Copper oxide generated two strongly temperature dependent absorption peaks at 324.8 and 327.4 nm. The melting point of copper oxide was determined to be too low for serious consideration as marker material.

  9. Optical Emission Spectroscopic Techniques for Low Electron Density Diagnostics

    SciTech Connect

    Ivkovic, M.

    2006-12-01

    This paper comprises an analysis of optical emission spectroscopy (OES) techniques and results of their application for diagnostics of middle and low electron densities in low temperature plasmas. The following OES diagnostic techniques based on: 1) line merging along spectral line series, 2) use of line shapes and Stark halfwidths of hydrogen Balmer lines, 3) line shape of helium lines with forbidden components and 4) use of molecular nitrogen bandhead intensities are studied, discussed, tested and applied and in some cases ugraded for electron density measurements. The overall comparative analysis is performed also.

  10. Strongly coupled versus uncoupled spin response to radio frequency interference effects: application to glutamate and glutamine in spectroscopic imaging.

    PubMed

    Snyder, Jeff; Thompson, Richard B; Wild, Jim M; Wilman, Alan H

    2008-05-01

    It is well known that comparable radio frequency (RF) wavelengths and human head dimensions at high fields can lead to an inhomogeneous RF field when using standard RF transmission. However, the impact of RF inhomogeneity on potential differences in quantification between coupled and uncoupled spins at longer echo times has not been investigated thoroughly. The consequence of this RF interference on metabolite quantification in spectroscopic imaging at 4.7 T was investigated for the strongly coupled spin systems of glutamate and glutamine at an echo time of 120 ms, and compared with the singlet response of choline. These effects were studied using a single-voxel PRESS sequence (alpha-2alpha-2alpha) with varying flip angle (alpha) from 90 degrees to 65 degrees in simulation, phantom, and in vivo experiments. Phantom metabolite yield decreased to 57% for choline and 27% for glutamate/glutamine in agreement with the simulations. Even a minor reduction from alpha = 85 degrees to 80 degrees produced a large difference between coupled and uncoupled yields, with a reduction of 7% for choline and 17% for glutamate/glutamine. Anecdotal in vivo spectroscopic imaging studies show similar trends, with large differences between choline and glutamate/glutamine yield over a small, 2.2 cm, region. These results demonstrate severe effects on metabolite yield due to RF variation between strongly coupled and uncoupled spin systems at long echo time, which complicates metabolite quantification.

  11. Understanding and controlling spin-systems using electron spin resonance techniques

    NASA Astrophysics Data System (ADS)

    Martens, Mathew

    the frequency of this nutation. Experimental findings fit well the analytical model developed. This process could lead to the use of multi-level spin systems as tunable solid state qubits. Finally, if quantum computing technologies are to be commercially realized, an on-chip method to address qubits must be developed. One way to incorporate SMMs to an on-chip device is by way of a coplanar waveguide (CPW) resonator. Efforts to create a resonator of this type to be used to perform low-temperature ESR on-chip will be described. Our work is focused on implementing such on-chip techniques in high magnetic fields, which is desirable for ESR-type of experiments in (quasi-)isotropic spin systems. Considerable attention is given to the coupling of these devices and a geometry is presented for a superconducting CPW resonator that is critically coupled. The effect of the magnetic field on the resonance position and its quality factor is addressed as well. Our devices show robust performance in field upwards of 1 Tesla and their use in performing on-chip ESR measurements seem promising.

  12. Use of Advanced Spectroscopic Techniques for Predicting the Mechanical Properties of Wood Composites

    Treesearch

    Timothy G. Rials; Stephen S. Kelley; Chi-Leung So

    2002-01-01

    Near infrared (NIR) spectroscopy was used to characterize a set of medium-density fiberboard (MDF) samples. This spectroscopic technique, in combination with projection to latent structures (PLS) modeling, effectively predicted the mechanical strength of MDF samples with a wide range of physical properties. The stiffness, strength, and internal bond properties of the...

  13. Use of different spectroscopic techniques in the analysis of Roman age wall paintings.

    PubMed

    Agnoli, Francesca; Calliari, Irene; Mazzocchin, Gian-Antonio

    2007-01-01

    In this paper the analysis of samples of Roman age wall paintings coming from: Pordenone, Vicenza and Verona is carried out by using three different techniques: energy dispersive x-rays spectroscopy (EDS), x-rays fluorescence (XRF) and proton induced x-rays emission (PIXE). The features of the three spectroscopic techniques in the analysis of samples of archaeological interest are discussed. The studied pigments were: cinnabar, yellow ochre, green earth, Egyptian blue and carbon black.

  14. Mössbauer spectroscopic study on spin crossover coordination polymer Fe(3-Clpy)2[Pd(CN)4

    NASA Astrophysics Data System (ADS)

    Kitazawa, Takafumi; Sekiya, Madoka; Kawasaki, Takeshi; Takahashi, Masashi

    2016-12-01

    57Fe Mössbauer spectroscopic results on the alternatively prepared spin crossover coordination polymer Fe(3-Clpy)2Pd(CN)4 sample I agree with those of SQUID data. Mössbauer specrum at RT shows two diffrent doublets which correspond to the HS1(inner doublet) and HS2(outer doublet). The intensity of the HS1 doublet decreases on cooling to 78 K at the expense of a new one featuring the LS singlet. Almost 100 % of HS1 change to LS singlet due to iron(II) ions coordinated by four N atoms of cyano groups and two N atoms of 3-Clpy ligand in the sample I. The SQUID data of the sample I prepared by a new direct contact method are different from those of the already reported Fe(3-Clpy)2Pd(CN)4 sample. The differences of the SQUID data are associated with particle size effects in molecule spin crossover samples.

  15. Characterization of Sorolla's gouache pigments by means of spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Roldán, Clodoaldo; Juanes, David; Ferrazza, Livio; Carballo, Jorgelina

    2016-02-01

    This paper presents the characterization of the Joaquín Sorolla's gouache sketches for the oil on canvas series "Vision of Spain" commissioned by A. M. Huntington to decorate the library of the Hispanic Society of America in New York. The analyses were focused on the identification of the elemental composition of the gouache pigments by means of portable EDXRF spectrometry in a non-destructive mode. Additionally, SEM-EDX and FTIR analyses of a selected set of micro-samples were carried out to identify completely the pigments, the paint technique and the binding media. The obtained results have confirmed the identification of lead and zinc white, vermillion, earth pigments, ochre, zinc yellow, chrome yellow, ultramarine, Prussian blue, chromium based and copper-arsenic based green pigments, bone black and carbon based black pigments, and the use of gum arabic as binding media in the gouache pigments.

  16. Studies of tropical fruit ripening using three different spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Huang, Jing; Li, Tianqi; Wu, Xiuxiang; Svanberg, Sune; Svanberg, Katarina

    2014-06-01

    We present a noninvasive method to study fruit ripening. The method is based on the combination of reflectance and fluorescence spectroscopies, as well as gas in scattering media absorption spectroscopy (GASMAS). Chlorophyll and oxygen are two of the most important constituents in the fruit ripening process. Reflectance and fluorescence spectroscopies were used to quantify the changes of chlorophyll and other chromophores. GASMAS, based on tunable diode laser absorption spectroscopy, was used to measure free molecular oxygen in the fruit tissue at 760 nm, based on the fact that the free gases have much narrower spectral imprints than those of solid materials. The fruit maturation and ripening processes can be followed by studying the changes of chlorophyll and oxygen contents with these three techniques.

  17. Fast magnetic resonance spectroscopic imaging techniques in human brain- applications in multiple sclerosis.

    PubMed

    Al-Iedani, Oun; Lechner-Scott, Jeannette; Ribbons, Karen; Ramadan, Saadallah

    2017-02-28

    Multi voxel magnetic resonance spectroscopic imaging (MRSI) is an important imaging tool that combines imaging and spectroscopic techniques. MRSI of the human brain has been beneficially applied to different clinical applications in neurology, particularly in neurooncology but also in multiple sclerosis, stroke and epilepsy. However, a major challenge in conventional MRSI is the longer acquisition time required for adequate signal to be collected. Fast MRSI of the brain in vivo is an alternative approach to reduce scanning time and make MRSI more clinically suitable.Fast MRSI can be categorised into spiral, echo-planar, parallel and turbo imaging techniques, each with its own strengths. After a brief introduction on the basics of non-invasive examination ((1)H-MRS) and localization techniques principles, different fast MRSI techniques will be discussed from their initial development to the recent innovations with particular emphasis on their capacity to record neurochemical changes in the brain in a variety of pathologies.The clinical applications of whole brain fast spectroscopic techniques, can assist in the assessment of neurochemical changes in the human brain and help in understanding the roles they play in disease. To give a good example of the utilities of these techniques in clinical context, MRSI application in multiple sclerosis was chosen. The available up to date and relevant literature is discussed and an outline of future research is presented.

  18. Spectroscopic, Structural, and Kinetic Investigation of the Ultrafast Spin Crossover in an Unusual Cobalt(II) Semiquinonate Radical Complex.

    PubMed

    Rupp, Fabian; Chevalier, Katharina; Graf, Michèle; Schmitz, Markus; Kelm, Harald; Grün, Anneken; Zimmer, Manuel; Gerhards, Markus; van Wüllen, Christoph; Krüger, Hans-Jörg; Diller, Rolf

    2017-02-10

    A comprehensive spectroscopic and structural investigation of [Co(II) (l-N4  tBu2 )(dbsq)][B(p-C6 H4 Cl)4 ] (1, l-N4  tBu2 =N,N'-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane, dbsq(1-) =3,5-di-tert-butylsemiquinonate), the first known octahedral complex with a low-spin (ls) Co(II) semiquinonate ground state, is reported. Above 200 K, solids as well as solutions of 1 exhibit thermally induced spin-crossover (SCO) from the ls to the high-spin (hs) Co(II) semiquinonate state instead of the frequently observed valence tautomerism from ls Co(III) catecholate to hs Co(II) semiquinonate. DFT calculations demonstrate that the (closed shell) Co(III) catecholate suffers from a triplet instability leading to the ls Co(II) semiquinonate ground state. The thorough temperature-dependent spectroscopic study of the SCO enables a photophysical investigation. Thus, by selective photoexcitation of the ls fraction of 1 in solution at room temperature, ultrafast conversion to the hs state is observed using femtosecond electronic and IR-vibrational (infrared) transient absorption spectroscopy. The kinetics of the photocycle is described by a stretched exponential with τ=3.3-3.6 ps and β=0.52-0.54, representing an upper limit for the hs-ls relaxation time. This is, to our knowledge, the fastest interconversion ever determined for a SCO complex, and is attributed to the special situation that in 1 a Co(II) complex is coordinated to a π-radical ligand allowing very efficient coupling between the ls and hs spin states. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Breath Analysis Using Laser Spectroscopic Techniques: Breath Biomarkers, Spectral Fingerprints, and Detection Limits

    PubMed Central

    Wang, Chuji; Sahay, Peeyush

    2009-01-01

    Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC) disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS), cavity ringdown spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), cavity enhanced absorption spectroscopy (CEAS), cavity leak-out spectroscopy (CALOS), photoacoustic spectroscopy (PAS), quartz-enhanced photoacoustic spectroscopy (QEPAS), and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS). Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis. PMID:22408503

  20. Breath analysis using laser spectroscopic techniques: breath biomarkers, spectral fingerprints, and detection limits.

    PubMed

    Wang, Chuji; Sahay, Peeyush

    2009-01-01

    Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC) disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS), cavity ringdown spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), cavity enhanced absorption spectroscopy (CEAS), cavity leak-out spectroscopy (CALOS), photoacoustic spectroscopy (PAS), quartz-enhanced photoacoustic spectroscopy (QEPAS), and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS). Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis.

  1. A flexible fast spin echo triple-echo Dixon technique.

    PubMed

    Son, Jong Bum; Hwang, Ken-Pin; Madewell, John E; Bayram, Ersin; Hazle, John D; Low, Russell N; Ma, Jingfei

    2017-03-01

    To develop a flexible fast spin echo (FSE) triple-echo Dixon (FTED) technique. An FSE pulse sequence was modified by replacing each readout gradient with three fast-switching bipolar readout gradients with minimal interecho dead time. The corresponding three echoes were used to generate three raw images with relative phase shifts of -θ, 0, and θ between water and fat signals. A region growing-based two-point Dixon phase correction algorithm was used to joint process two separate pairs of the three raw images, yielding a final set of water-only and fat-only images. The flexible FTED technique was implemented on 1.5T and 3.0T scanners and evaluated in five subjects for fat-suppressed T2-weighted imaging and in one subject for post-contrast fat-suppressed T1-weighted imaging. The flexible FTED technique achieved a high data acquisition efficiency, comparable to that of FSE, and was flexible in scan protocols. The joint two-point Dixon phase correction algorithm helped to ensure consistency in the processing of the two separate pairs of raw images. Reliable and uniform separation of water and fat was achieved in all of the test cases. The flexible FTED technique incorporates the benefits of both FSE and Dixon imaging and provided more flexibility than the original FTED in applications such as fat-suppressed T2-weighted and T1-weighted imaging. Magn Reson Med 77:1049-1057, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  2. Non-Destructive and rapid evaluation of staple foods quality by using spectroscopic techniques: A review.

    PubMed

    Su, Wen-Hao; He, Hong-Ju; Sun, Da-Wen

    2017-03-24

    Staple foods, including cereals, legumes, and root/tuber crops, dominate the daily diet of humans by providing valuable proteins, starch, oils, minerals, and vitamins. Quality evaluation of staple foods is primarily carried out on sensory (e.g. external defect, color), adulteration (e.g. species, origin), chemical (e.g. starch, proteins), mycotoxin (e.g. Fusarium toxin, aflatoxin), parasitic infection (e.g. weevil, beetle), and internal physiological (e.g. hollow heart, black heart) aspects. Conventional methods for the quality assessment of staple foods are always laborious, destructive, and time-consuming. Requirements for online monitoring of staple foods have been proposed to encourage the development of rapid, reagentless, and noninvasive techniques. Spectroscopic techniques, such as visible-infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance spectroscopy, and spectral imaging, have been introduced as promising analytical tools and applied for the quality evaluation of staple foods. This review summarizes the recent applications and progress of such spectroscopic techniques in determining various qualities of staple foods. Besides, challenges and future trends of these spectroscopic techniques are also presented.

  3. Multiple spin-echo spectroscopic imaging for rapid quantitative assessment of N-acetylaspartate and lactate in acute stroke.

    PubMed

    Stengel, Astrid; Neumann-Haefelin, Tobias; Singer, Oliver C; Neumann-Haefelin, Claudia; Zanella, Friedhelm E; Lanfermann, Heinrich; Pilatus, Ulrich

    2004-08-01

    Monitoring the signal levels of lactate (Lac) and N-acetylaspartate (NAA) by chemical shift imaging can provide additional knowledge about tissue damage in acute stroke. Despite the need for this metabolic information, spectroscopic imaging (SI) has not been used routinely for acute stroke patients, mainly due to the long acquisition time required. The presented data demonstrate that the application of a fast multiple spin-echo (MSE) SI sequence can reduce the measurement time to 6 min (four spin echoes per echo train, 32 x 32 matrix). Quantification of Lac and NAA in terms of absolute concentrations (i.e., mmol/l) can be achieved by means of the phantom replacement approach, with correction terms for the longitudinal and transversal relaxation adapted to the multiple spin-echo sequence. In this pilot study of 10 stroke patients (symptom onset < 24 hr), metabolite concentrations obtained from MSE-SI add important information regarding tissue viability that is not provided by other sequences (e.g., diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI)). Metabolic changes extended beyond the borders of the apparent diffusion coefficient (ADC) lesion in nine of the 10 patients, showing a rise in Lac concentrations up to 18 mmol/l, while NAA levels sometimes dropped below the detection level. Considerable differences among the patients in terms of the Lac concentrations and the size of the SI-ADC mismatch were observed.

  4. Advanced in situ spectroscopic techniques and their applications in environmental biogeochemistry: introduction to the special section.

    PubMed

    Lombi, Enzo; Hettiarachchi, Ganga M; Scheckel, Kirk G

    2011-01-01

    Understanding the molecular-scale complexities and interplay of chemical and biological processes of contaminants at solid, liquid, and gas interfaces is a fundamental and crucial element to enhance our understanding of anthropogenic environmental impacts. The ability to describe the complexity of environmental biogeochemical reaction mechanisms relies on our analytical ability through the application and developmemnt of advanced spectroscopic techniques. Accompanying this introductory article are nine papers that either review advanced in situ spectroscopic methods or present original research utilizing these techniques. This collection of articles summarizes the challenges facing environmental biogeochemistry, highlights the recent advances and scientific gaps, and provides an outlook into future research that may benefit from the use of in situ spectroscopic approaches. The use of synchrotron-based techniques and other methods are discussed in detail, as is the importance to integrate multiple analytical approaches to confirm results of complementary procedures or to fill data gaps. We also argue that future direction in research will be driven, in addition to recent analytical developments, by emerging factors such as the need for risk assessment of new materials (i.e., nanotechnologies) and the realization that biogeochemical processes need to be investigated in situ under environmentally relevant conditions.

  5. Application of spectroscopic techniques for the study of paper documents: A survey

    NASA Astrophysics Data System (ADS)

    Manso, M.; Carvalho, M. L.

    2009-06-01

    For many centuries paper was the main material for recording cultural achievements all over the world. Paper is mostly made from cellulose with small amounts of organic and inorganic additives, which allow its identification and characterization and may also contribute to its degradation. Prior to 1850, paper was made entirely from rags, using hemp, flax and cotton fibres. After this period, due to the enormous increase in demand, wood pulp began to be commonly used as raw material, resulting in rapid degradation of paper. Spectroscopic techniques represent one of the most powerful tools to investigate the constituents of paper documents in order to establish its identification and its state of degradation. This review describes the application of selected spectroscopic techniques used for paper characterization and conservation. The spectroscopic techniques that have been used and will be reviewed include: Fourier-Transform Infrared spectroscopy, Raman spectroscopy, Nuclear Magnetic Resonance spectroscopy, X-Ray spectroscopy, Laser-based Spectroscopy, Inductively Coupled Mass Spectroscopy, Laser ablation, Atomic Absorption Spectroscopy and X-Ray Photoelectron Spectroscopy.

  6. Mean field spin glasses treated with PDE techniques

    NASA Astrophysics Data System (ADS)

    Barra, Adriano; Del Ferraro, Gino; Tantari, Daniele

    2013-07-01

    Following an original idea of Guerra, in these notes we analyze the Sherrington-Kirkpatrick model from different perspectives, all sharing the underlying approach which consists in linking the resolution of the statistical mechanics of the model (e.g. solving for the free energy) to well-known partial differential equation (PDE) problems (in suitable spaces). The plan is then to solve the related PDE using techniques involved in their native field and lastly bringing back the solution in the proper statistical mechanics framework. Within this strand, after a streamlined test-case on the Curie-Weiss model to highlight the methods more than the physics behind, we solve the SK both at the replica symmetric and at the 1-RSB level, obtaining the correct expression for the free energy via an analogy to a Fourier equation and for the self-consistencies with an analogy to a Burger equation, whose shock wave develops exactly at critical noise level (triggering the phase transition). Our approach, beyond acting as a new alternative method (with respect to the standard routes) for tackling the complexity of spin glasses, links symmetries in PDE theory with constraints in statistical mechanics and, as a novel result from the theoretical physics perspective, we obtain a new class of polynomial identities (namely of Aizenman-Contucci type, but merged within the Guerra's broken replica measures), whose interest lies in understanding, via the recent Panchenko breakthroughs, how to force the overlap organization to the ultrametric tree predicted by Parisi.

  7. Advanced techniques for all-electrical spectroscopy on spin caloric phenomena

    NASA Astrophysics Data System (ADS)

    Huber, R.; Klemm, P.; Neusser, S.; Botters, B.; Wittmann, A.; Weiler, M.; Goennenwein, S. T. B.; Heyn, C.; Schneider, M.; Böni, P.; Grundler, D.

    2010-04-01

    Spin-dependent properties of nanomagnets and magnetic/nonmagnetic hybrid systems have gained a renewed interest after the discovery of spin caloric transport phenomena. To explore such properties in detail, advanced techniques need to be developed. In this paper we report novel approaches to study both the magneto-thermal and magneto-mechanical characteristics of hybrid systems. These techniques involve in particular broadband spectroscopy of spin dynamics and surface acoustic waves in the GHz frequency regime. By these means we investigate ferromagnet/semiconductor hybrid systems to explore spin pumping and the Seebeck effect as well as ferromagnet/piezoelectric hybrid systems to address magneto-mechanical coupling at high frequencies.

  8. Field dependence of the spin state and spectroscopic modes of multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Fishman, Randy S.

    2013-06-01

    The spectroscopic modes of multiferroic BiFeO3 provide detailed information about the very small anisotropy and Dzyaloshinskii-Moriya (DM) interactions responsible for the long-wavelength, distorted cycloid below TN=640 K. A microscopic model that includes two DM interactions and easy-axis anisotropy predicts both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field applied along a cubic axis. While only six modes are optically active in zero field, all modes at the cycloidal wave vector are activated by a magnetic field. The three magnetic domains of the cycloid are degenerate in zero field but one domain has lower energy than the other two in nonzero field. Measurements imply that the higher-energy domains are depopulated above about 6 T and have a maximum critical field of 16 T, below the critical field of 19 T for the lowest-energy domain. Despite the excellent agreement with the measured spectroscopic frequencies, some discrepancies with the measured spectroscopic intensities suggest that other weak interactions may be missing from the model.

  9. Measurement of optical nonlinearity by antiresonant ring interferometric nonlinear spectroscopic (ARINS) technique

    NASA Astrophysics Data System (ADS)

    Bhushan, B.

    2016-08-01

    We have reported the measurement of third-order optical nonlinearity by antiresonant ring interferometric nonlinear spectroscopic (ARINS) technique and discussed its usefulness over other popular measuring techniques such as Z-scan, degenerate four wave mixing (DFWM) and third harmonic generation (THG). The measurement has been simulated theoretically by taking different numerical values as well as sign of δ, which is a key parameter of ARINS. The technique has been benchmarked using toluene and the theoretical simulation has been substantiated experimentally by measuring the nonlinear optical coefficients ( n 2 and β) of two different samples. The disadvantages of the technique have also been discussed. However, a number of advantages of ARINS override its disadvantages and therefore, ARINS may be preferred over other measuring techniques for the measurement of nonlinear optical parameters.

  10. Novel Infrared Coherent Sources and Techniques for Spectroscopic Test of Fundamental Physics Principles

    NASA Astrophysics Data System (ADS)

    Pastor, P. Cancio; Galli, I.; Giusfredi, G.; Mazzotti, D.; De Natale, P.

    2013-06-01

    Recent achievements in high sensitivity and precision molecular spectroscopy in the mid-IR open new perspectives for experiments looking for possible violations of the basic postulates in quantum mechanics or quantum electro-dynamics in simple molecular systems. A new generation of hybrid infrared sources, including a direct link to optical frequency comb synthesizers (OFCSs) is under development. They provide metrological frequency precision and sensitivities that have achieved record levels of tens of parts-per-quadrillion when appropriate spectroscopic techniques are implemented. Such very recent developments will be reviewed. An example of possible application to the test of fundamental principles is attacking the symmetrization postulate (SP). Actually, the requirement of symmetry of the wave function under exchange of identical particles has a striking demonstration in the spectra of molecules including identical nuclei. The basic idea of the spectroscopic tests is to search with extremely high sensitivity for (weak) molecular lines involving the forbidden states. Since the early test of SP violation in bosonic particles, ^{12}C^{16}O_2 molecule has been considered a playground system. An upper limit of 10^{-11} to such violation was measured more than one decade ago by our group. The recent developed spectroscopic technique^{d,e} measured a minimum detected CO_2 gas pressures, in a 1-Hz bandwidth, of a few tens of femtobar, which could improve the previous test by more than two orders of magnitude. Progress in high sensitivity spectroscopic measurements in view of new violation tests will be reviewed, to investigate molecules with two and also three identical nuclei, like SO_3 and NH_3. I. Galli et al., Opt. Lett. 35, 3616 (2010). I. Ricciardi et al., Opt. Express 20, 9178 (2012). S. Borri, et al., Opt. Lett. 37, 1011 (2012). G. Giusfredi et al., Phys. Rev. Lett. 104, 110801(2010). I. Galli et al., Phys. Rev. Lett. 107, 270802 (2011). D. Mazzotti et al

  11. The role of simulation chambers in the development of spectroscopic techniques: campaigns at EUPHORE

    NASA Astrophysics Data System (ADS)

    Ródenas, Milagros; Muñoz, Amalia; Euphore Team

    2016-04-01

    Simulation chambers represent a very useful tool for the study of chemical reactions and their products, but also to characterize instruments. The development of spectroscopic techniques throughout the last decades has benefited from tests and intercomparison exercises carried out in chambers. In fact, instruments can be exposed to various controlled atmospheric scenarios that account for different environmental conditions, eliminating the uncertainties associated to fluctuations of the air mass, which must be taken into account when extrapolating results to the real conditions. Hence, a given instrument can be characterized by assessing its precision, accuracy, detection limits, time response and potential interferences in the presence of other chemical compounds, aerosols, etc. This implies that the instrument can be calibrated and validated, which allows to enhance the features of the instrument. Moreover, chambers are also the scenario of intercomparison trials, permitting multiple instruments to sample from the same well-mixed air mass simultaneously. An overview of different campaigns to characterize and/or intercompare spectroscopic techniques that have taken place in simulation chambers will be given; in particular, those carried out at EUPHORE (two twin domes, 200 m3 each, Spain), where various intercomparison exercises have been deployed under the frame of European projects (e.g. TOXIC, FIONA, PSOA campaigns supported by EUROCHAMP-II). With the common aim of measuring given compounds (e.g. HONO, NO2, OH, glyoxal, m-glyoxal, etc), an important number of spectroscopic instruments and institutions have been involved in chamber experiments, having the chance to intercompare among them and also with other non-spectroscopic systems (e.g. monitors, cromatographs, etc) or model simulations.

  12. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    SciTech Connect

    Sawyer, Karma Rae

    2008-12-01

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  13. Glucose Oxidase Adsorption on Sequential Adsorbed Polyelectrolyte Films Studied by Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Tristán, Ferdinando; Solís, Araceli; Palestino, Gabriela; Gergely, Csilla; Cuisinier, Frédéric; Pérez, Elías

    2005-04-01

    The adsorption of Glucose Oxidase (GOX) on layers of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) deposited on Sequentially Adsorbed Polyelectrolyte Films (SAPFs) were studied by three different spectroscopic techniques. These techniques are: Optical Wave Light Spectroscopy (OWLS) to measure surface density; Fluorescence Resonance Energy Transfer (FRET) to verify the adsorption of GOX on the surface; and Fourier Transform Infrared Spectroscopy in Attenuated Total Reflection mode (FTIR-HATR) to inspect local structure of polyelectrolytes and GOX. Two positive and two negative polyelectrolytes are used: Cationic poly(ethyleneimine) (PEI) and poly(allylamine hydrochloride) (PAH) and anionic poly(sodium 4-styrene sulfonate) (PSS) and poly(acrylic acid) (PAA). These spectroscopic techniques do not require any labeling for GOX or SAPFs, specifically GOX and PSS are naturally fluorescent and are used as a couple donor-acceptor for the FRET technique. The SAPFs are formed by a (PEI)-(PSS/PAH)2 film followed by (PAA/PAH)n bilayers. GOX is finally deposited on top of SAPFs at different values of n (n=1..5). Our results show that GOX is adsorbed on positive ended SAPFs forming a monolayer. Contrary, GOX adsorption is not observed on negative ended film polyelectrolyte. GOX stability was tested adding a positive and a negative polyelectrolyte after GOX adsorption. Protein is partially removed by PAH and PAA, with lesser force by PAA.

  14. Effects of spin diffusion on electron spin relaxation time measured with a time-resolved microscopic photoluminescence technique

    SciTech Connect

    Ikeda, Kazuhiro Kawaguchi, Hitoshi

    2015-02-07

    We performed measurements at room temperature for a GaAs/AlGaAs multiple quantum well grown on GaAs(110) using a time-resolved microscopic photoluminescence (micro-PL) technique to find what effects spin diffusion had on the measured electron spin relaxation time, τ{sub s}, and developed a method of estimating the spin diffusion coefficient, D{sub s}, using the measured data and the coupled drift-diffusion equations for spin polarized electrons. The spatial nonuniformities of τ{sub s} and the initial degree of electron spin polarization caused by the pump intensity distribution inside the focal spot were taken into account to explain the dependence of τ{sub s} on the measured spot size, i.e., a longer τ{sub s} for a smaller spot size. We estimated D{sub s} as ∼100 cm{sup 2}/s, which is similar to a value reported in the literature. We also provided a qualitative understanding on how spin diffusion lengthens τ{sub s} in micro-PL measurements.

  15. Methodological considerations of electron spin resonance spin trapping techniques for measuring reactive oxygen species generated from metal oxide nanomaterials

    NASA Astrophysics Data System (ADS)

    Jeong, Min Sook; Yu, Kyeong-Nam; Chung, Hyun Hoon; Park, Soo Jin; Lee, Ah Young; Song, Mi Ryoung; Cho, Myung-Haing; Kim, Jun Sung

    2016-05-01

    Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation time with spin trapping agents. Based on our results, each spin trapping agent should be given the proper incubation time. For nanomaterials having magnetic properties, it is useful to remove these nanomaterials via centrifugation after reacting with spin trapping agents. Sonication for the purpose of sample dispersion and sample light exposure should be controlled during ESR in order to enhance the obtained ROS signal. This report will allow researchers to better design ESR spin trapping applications involving nanomaterials.

  16. Meniscal tears: comparison of the conventional spin-echo and fast spin-echo techniques through image processing

    PubMed Central

    2014-01-01

    Background Conventional spin-echo (PD-CSE) and fast spin-echo (PD-FSE) techniques are frequently used to detect meniscal tears. However, the time delay for imaging with PD-CSE has resulted in its replacement with faster techniques, such as proton density fast spin-echo (PD-FSE), which has become a frequent tool at most diagnostic centres. Qualitative analysis shows that the PD-CSE technique is more sensitive, but other authors have not found significant differences between the aforementioned techniques. Therefore, we performed a quantitative analysis in this study that aims to measure differences in the quality of the images obtained with both techniques. Methods We compared the PD-CSE and PD-FSE techniques by quantitatively analysing the obtained proton density images: the area shown, as well as the brightness and lesion contrast of the obtained image. A set of 100 images from 50 patients thought to contain meniscal tears of the knee were selected. These 100 images were obtained from all individuals using both the PD-CSE and PD-FSE techniques. The images were processed using software developed in Delphi. In addition to these quantifications, three physicians, who are specialists in radiology and capable of analysing magnetic resonance (MR) images of the musculoskeletal system, qualitatively analysed the diagnostic sensitivity of both techniques. Results On average, samples obtained via the PD-CSE technique contained 22% more pixels in the lesion area. The contrast differed by 28%, and the brightness differed by 31%. The two techniques were correlated using Student’s t-test, which showed a statistically significant difference. The specialists detected meniscal tears in 30 of the images obtained via the PD-CSE technique, while only 72% of these cases were detected via the PD-FSE technique. Conclusions The PD-CSE technique was shown to be superior to PD-FSE for all of the evaluated properties, making its selection preferable. PMID:24673813

  17. How to Calculate Spin-Spin Coupling and Spin-Rotation Coupling Strengths and Their Uncertainties from Spectroscopic Data: Application to the c(1^3Σ_g^+) State of Diatomic Lithium

    NASA Astrophysics Data System (ADS)

    Dattani, Nikesh S.; Li, Xuan

    2013-06-01

    Recent high-resolution (± 0.00002 cm^{-1}) photo-association spectroscopy (PAS) data of seven previously unexplored vibrational levels of the 1^3Σ_g^+ state of Li_2 have allowed for the first ever experimental determination of the spin-spin (λ_v) and spin-rotation (γ_v) coupling constants in a diatomic lithium system. For triplet states of diatomic molecules such as the 1^3Σ_g^+ state of Li_2, the three spin-spin/spin-rotation resolved energies associated with a ro-vibrational state |v,N> were expressed explicity in terms of B_v, λ_v, and γ_v in 1929 by Kramer's first-order formulas and then in 1937 by Schlapp's more refined formulas. Given spectroscopic data, while it has never been difficult to extract λ_v and γ_v from Schlapp's formulas, it has been a challenge to reliably predict how accurate these extracted values are. This is for two reasons: (1) the lack of a rigorous method to estimate the uncertainty in B_v, (2) the non-linearity of Schlapp's coupled equations has meant that traditionally they have had to be solved numerically by Newton iterations which makes error propagation difficult. The former challenge has been this year solved by Le Roy with a modification of Hutson's perturbation theory of, and the latter problem has now been solved by symbolic computing software that solves Schlapp's coupled non-linear equations analytically for the first time since their introduction in 1937. M. Semczuk, X. Li, W. Gunton, M. Haw, N. Dattani, J. Witz, A. Mills, D. Jones, K. Madison, Physical Review A {87}, XX (2013) H. Kramers, Zeitschrift fur Physik {53}, 422 (1929) R. Schlapp, Physical Review {51}, 342 (1937) J. Hutson, J. Phys. B, {14}, 851 (1981)

  18. Interferometrically stable, enclosed, spinning sample cell for spectroscopic experiments on air-sensitive samples

    NASA Astrophysics Data System (ADS)

    Baranov, Dmitry; Hill, Robert J.; Ryu, Jisu; Park, Samuel D.; Huerta-Viga, Adriana; Carollo, Alexa R.; Jonas, David M.

    2017-01-01

    In experiments with high photon flux, it is necessary to rapidly remove the sample from the beam and to delay re-excitation until the sample has returned to equilibrium. Rapid and complete sample exchange has been a challenge for air-sensitive samples and for vibration-sensitive experiments. Here, a compact spinning sample cell for air and moisture sensitive liquid and thin film samples is described. The principal parts of the cell are a copper gasket sealed enclosure, a 2.5 in. hard disk drive motor, and a reusable, chemically inert glass sandwich cell. The enclosure provides an oxygen and water free environment at the 1 ppm level, as demonstrated by multi-day tests with sodium benzophenone ketyl radical. Inside the enclosure, the glass sandwich cell spins at ≈70 Hz to generate tangential speeds of 7-12 m/s that enable complete sample exchange at 100 kHz repetition rates. The spinning cell is acoustically silent and compatible with a ±1 nm rms displacement stability interferometer. In order to enable the use of the spinning cell, we discuss centrifugation and how to prevent it, introduce the cycle-averaged resampling rate to characterize repetitive excitation, and develop a figure of merit for a long-lived photoproduct buildup.

  19. Interferometrically stable, enclosed, spinning sample cell for spectroscopic experiments on air-sensitive samples.

    PubMed

    Baranov, Dmitry; Hill, Robert J; Ryu, Jisu; Park, Samuel D; Huerta-Viga, Adriana; Carollo, Alexa R; Jonas, David M

    2017-01-01

    In experiments with high photon flux, it is necessary to rapidly remove the sample from the beam and to delay re-excitation until the sample has returned to equilibrium. Rapid and complete sample exchange has been a challenge for air-sensitive samples and for vibration-sensitive experiments. Here, a compact spinning sample cell for air and moisture sensitive liquid and thin film samples is described. The principal parts of the cell are a copper gasket sealed enclosure, a 2.5 in. hard disk drive motor, and a reusable, chemically inert glass sandwich cell. The enclosure provides an oxygen and water free environment at the 1 ppm level, as demonstrated by multi-day tests with sodium benzophenone ketyl radical. Inside the enclosure, the glass sandwich cell spins at ≈70 Hz to generate tangential speeds of 7-12 m/s that enable complete sample exchange at 100 kHz repetition rates. The spinning cell is acoustically silent and compatible with a ±1 nm rms displacement stability interferometer. In order to enable the use of the spinning cell, we discuss centrifugation and how to prevent it, introduce the cycle-averaged resampling rate to characterize repetitive excitation, and develop a figure of merit for a long-lived photoproduct buildup.

  20. Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control

    SciTech Connect

    Czerwinski, Kenneth; Weck, Phil

    2013-09-13

    Ultraviolet–visible spectroscopy (UV–Visible) and time-resolved laser fluorescence spectroscopy (TRLFS) optical techniques can permit on-line analysis of actinide elements in a solvent extraction process in real time. These techniques have been used for measuring actinide speciation and concentration under laboratory conditions and are easily adaptable to multiple sampling geometries, such as dip probes, fiber-optic sample cells, and flow-through cell geometries. To fully exploit these techniques, researchers must determine the fundamental speciation of target actinides and the resulting influence on spectroscopic properties. Detection limits, process conditions, and speciation of key actinide components can be established and utilized in a range of areas, particularly those related to materials accountability and process control. Through this project, researchers will develop tools and spectroscopic techniques to evaluate solution extraction conditions and concentrations of U, Pu, and Cm in extraction processes, addressing areas of process control and materials accountability. The team will evaluate UV– Visible and TRLFS for use in solvent extraction-based separations. Ongoing research is examining efficacy of UV-Visible spectroscopy to evaluate uranium and plutonium speciation under conditions found in the UREX process and using TRLFS to evaluate Cm speciation and concentration in the TALSPEAK process. A uranyl and plutonium nitrate UV–Visible spectroscopy study met with success, which supports the utility and continued exploration of spectroscopic methods for evaluation of actinide concentrations and solution conditions for other aspects of the UREX+ solvent extraction scheme. This project will examine U and Pu absorbance in TRUEX and TALSPEAK, perform detailed examination of Cm in TRUEX and TALSPEAK, study U laser fluorescence, and apply project data to contactors. The team will also determine peak ratios as a function of solution concentrations for the

  1. A COMPARISON OF SPECTROSCOPIC VERSUS IMAGING TECHNIQUES FOR DETECTING CLOSE COMPANIONS TO KEPLER OBJECTS OF INTEREST

    SciTech Connect

    Teske, Johanna K.; Everett, Mark E.; Hirsch, Lea; Furlan, Elise; Ciardi, David R.; Horch, Elliott P.; Howell, Steve B.; Gonzales, Erica; Crepp, Justin R.

    2015-11-15

    Kepler planet candidates require both spectroscopic and imaging follow-up observations to rule out false positives and detect blended stars. Traditionally, spectroscopy and high-resolution imaging have probed different host star companion parameter spaces, the former detecting tight binaries and the latter detecting wider bound companions as well as chance background stars. In this paper, we examine a sample of 11 Kepler host stars with companions detected by two techniques—near-infrared adaptive optics and/or optical speckle interferometry imaging, and a new spectroscopic deblending method. We compare the companion effective temperatures (T{sub eff}) and flux ratios (F{sub B}/F{sub A}, where A is the primary and B is the companion) derived from each technique and find no cases where both companion parameters agree within 1σ errors. In 3/11 cases the companion T{sub eff} values agree within 1σ errors, and in 2/11 cases the companion F{sub B}/F{sub A} values agree within 1σ errors. Examining each Kepler system individually considering multiple avenues (isochrone mapping, contrast curves, probability of being bound), we suggest two cases for which the techniques most likely agree in their companion detections (detect the same companion star). Overall, our results support the advantage that the spectroscopic deblending technique has for finding very close-in companions (θ ≲ 0.″02–0.″05) that are not easily detectable with imaging. However, we also specifically show how high-contrast AO and speckle imaging observations detect companions at larger separations (θ ≥ 0.″02–0.″05) that are missed by the spectroscopic technique, provide additional information for characterizing the companion and its potential contamination (e.g., position angle, separation, magnitude differences), and cover a wider range of primary star effective temperatures. The investigation presented here illustrates the utility of combining the two techniques to reveal higher

  2. Vibrational Spectroscopic Microscopy: Raman, Near-Infrared and Mid-Infrared Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Lewis, E. Neil; Levin, Ira W.

    1995-02-01

    New instrumental approaches for performing vibrational Raman, near-infrared and mid-infrared spectroscopic imaging microscopy are described. The instruments integrate imaging quality filters such as acousto-optic tunable filters (AOTFs), with visible charge-coupled device (CCD) and infrared focal-plane array detectors. These systems are used in conjunction with infinity-corrected, refractive microscopes for operation in the visible and near-infrared spectral regions and with Cassegrainian reflective optics for operation in the mid-infrared spectral interval. Chemically specific images at moderate spectral resolution (2 nm) and high spatial resolution (1 [mu]m) can be collected rapidly and noninvasively. Image data are presented containing 128 × 128 pixels, although significantly larger format images can be collected in approximately the same time. The instruments can be readily configured for both absorption and reflectance spectroscopies. We present Raman emission images of polystyrene microspheres and a lipid/amino acid mixture and near-infrared images of onion epidermis and a hydrated phospholipid dispersion. Images generated from mid-infrared spectral data are presented for a KBr disk containing nonhomogeneous domains of lipid and for 50-[mu]m slices of monkey cerebellum. These are the first results illustrating the use of infrared focal-plane array detectors as chemically specific spectroscopic imaging devices and demonstrating their application in biomolecular areas. Extensions and future applications of the various vibrational spectroscopic imaging techniques are discussed.

  3. Optical detection of middle ear infection using spectroscopic techniques: phantom experiments

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Huang, Jing; Li, Tianqi; Svanberg, Sune; Svanberg, Katarina

    2015-05-01

    A noninvasive optical technique, which is based on a combination of reflectance spectroscopy and gas in scattering media absorption spectroscopy, is demonstrated. It has the potential to improve diagnostics of middle ear infections. An ear phantom prepared with a tissue cavity, which was covered with scattering material, was used for spectroscopic measurements. Diffuse reflectance spectra of the phantom eardrum were measured with a reflectance probe. The presence of oxygen and water vapor as well as gas exchange in the phantom cavity were studied with a specially designed fiber-optic probe for backscattering detection geometry. The results suggest that this method can be developed for improved clinical detection of middle ear infection.

  4. Optical detection of middle ear infection using spectroscopic techniques: phantom experiments.

    PubMed

    Zhang, Hao; Huang, Jing; Li, Tianqi; Svanberg, Sune; Svanberg, Katarina

    2015-05-01

    A noninvasive optical technique, which is based on a combination of reflectance spectroscopy and gas in scattering media absorption spectroscopy, is demonstrated. It has the potential to improve diagnostics of middle ear infections. An ear phantom prepared with a tissue cavity, which was covered with scattering material, was used for spectroscopic measurements. Diffuse reflectance spectra of the phantom eardrum were measured with a reflectance probe. The presence of oxygen and water vapor as well as gas exchange in the phantom cavity were studied with a specially designed fiber-optic probe for backscattering detection geometry. The results suggest that this method can be developed for improved clinical detection of middle ear infection.

  5. A versatile setup using femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering

    SciTech Connect

    Shen, Yujie; Voronine, Dmitri V.; Sokolov, Alexei V.; Scully, Marlan O.

    2015-08-15

    We report a versatile setup based on the femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering. The setup uses a femtosecond Ti:Sapphire oscillator source and a folded 4f pulse shaper, in which the pulse shaping is carried out through conventional optical elements and does not require a spatial light modulator. Our setup is simple in alignment, and can be easily switched between the collinear single-beam and the noncollinear two-beam configurations. We demonstrate the capability for investigating both transparent and highly scattering samples by detecting transmitted and reflected signals, respectively.

  6. A versatile setup using femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering.

    PubMed

    Shen, Yujie; Voronine, Dmitri V; Sokolov, Alexei V; Scully, Marlan O

    2015-08-01

    We report a versatile setup based on the femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman scattering. The setup uses a femtosecond Ti:Sapphire oscillator source and a folded 4f pulse shaper, in which the pulse shaping is carried out through conventional optical elements and does not require a spatial light modulator. Our setup is simple in alignment, and can be easily switched between the collinear single-beam and the noncollinear two-beam configurations. We demonstrate the capability for investigating both transparent and highly scattering samples by detecting transmitted and reflected signals, respectively.

  7. FAST CARS: Engineering a laser spectroscopic technique for rapid identification of bacterial spores

    PubMed Central

    Scully, M. O.; Kattawar, G. W.; Lucht, R. P.; Opatrný, T.; Pilloff, H.; Rebane, A.; Sokolov, A. V.; Zubairy, M. S.

    2002-01-01

    Airborne contaminants, e.g., bacterial spores, are usually analyzed by time-consuming microscopic, chemical, and biological assays. Current research into real-time laser spectroscopic detectors of such contaminants is based on e.g., resonance fluorescence. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. However, generating and using maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is challenging. In particular, the short dephasing times and rapid internal conversion rates are major obstacles. However, adiabatic fast passage techniques and the ability to generate combs of phase-coherent femtosecond pulses provide tools for the generation and utilization of maximal quantum coherence in large molecules and biopolymers. We call this technique FAST CARS (femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman spectroscopy), and the present article proposes and analyses ways in which it could be used to rapidly identify preselected molecules in real time. PMID:12177405

  8. Spin state and spectroscopic modes of multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Fishman, Randy S.; Haraldsen, Jason T.; Furukawa, Nobuo; Miyahara, Shin

    2013-04-01

    Spectroscopic modes provide the most sensitive probe of the very weak interactions responsible for the properties of the long-wavelength cycloid in the multiferroic phase of BiFeO3 below TN≈640 K. Three of the four modes measured by terahertz (THz) and Raman spectroscopies were recently identified using a simple microscopic model. While a Dzyaloshinskii-Moriya (DM) interaction D along [-1,2,-1] induces a cycloid with wave vector (2π/a)(0.5+δ,0.5,0.5-δ) (δ≈0.0045), easy-axis anisotropy K along the [1,1,1] direction of the electric polarization P induces higher harmonics of the cycloid, which split the Ψ1 modes at 2.49 and 2.67 meV and activate the Φ2 mode at 3.38 meV. However, that model could not explain the observed low-frequency mode at about 2.17 meV. We now demonstrate that an additional DM interaction D' along [1,1,1] not only produces the observed weak ferromagnetic moment of the high-field phase above 18 T but also activates the spectroscopic matrix elements of the nearly degenerate, low-frequency Ψ0 and Φ1 modes, although their scattering intensities remain extremely weak. Even in the absence of easy-axis anisotropy, D' produces cycloidal harmonics that split Ψ1 and activate Φ2. However, the observed mode frequencies and selection rules require that both D' and K are nonzero. This work also resolves an earlier disagreement between spectroscopic and inelastic neutron-scattering measurements.

  9. Explaining the Cyclic Voltammetry of a Poly(1,4-phenylene-ethynylene)-alt-poly(1,4-phenylene-vinylene) Copolymer upon Oxidation by using Spectroscopic Techniques.

    PubMed

    Enengl, Christina; Enengl, Sandra; Bouguerra, Nassima; Havlicek, Marek; Neugebauer, Helmut; Egbe, Daniel A M

    2017-01-04

    Poly(1,4-phenylene-ethynylene)-alt-poly(1,4-phenylene-vinylene) (PPE-PPV) copolymers have attracted quite a lot of attention in the last few years for electronic device applications owing to their enhanced fluorescence. In this work, we focus on one particular PPE-PPV copolymer with dissymmetrically substituted 1,4-phenylene-ethynylene and symmetrically substituted 1,4-phenylene-vinylene building units. Six successively performed cyclic voltammograms are presented, measured during the oxidation reactions. As the oxidation onset of the electrochemical reaction shifts to lower potentials in each cycle, this behavior is elucidated by using spectroscopic techniques ranging from UV/Vis/near-IR to mid-IR including spin-resonance techniques. Hence, these findings help to explain some of the copolymer's most advantageous properties in terms of possible oxidation products. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Spectroscopic Localization by Simultaneous Acquisition of the Double-Spin and Stimulated Echoes

    PubMed Central

    Tal, Assaf; Gonen, Oded

    2014-01-01

    Purpose To design a proton MR spectroscopy (1H-MRS) localization sequence that combines the signal-to-noise-ratio (SNR) benefits of Point Resolved Spectroscopy (PRESS) with the high pulse bandwidths, low chemical shift displacements (CSD), low specific absorption rates (SAR), short echo times (TE) and superior radio-frequency transmit field (B1+) immunity of Stimulated Echo Acquisition Mode (STEAM), by simultaneously refocusing and acquiring both the double-spin and stimulated echo coherence pathways from the volume of interest. Methods We propose a family of 1H-MRS sequences comprising three orthogonal spatially-selective pulses with flip angles 90°<α, β, γ<128°. The stimulated and double-spin echo are refocused in-phase simultaneously by altering the pulses’ phases, flip angles and timing, as well as the inter-pulse gradient spoiling moments. The ≈90° nutations of α, β, γ provide STEAM-like advantages (lower SAR, in-plane CSD and TE; greater B1+ immunity), but with SNRs comparable with PRESS. Results Phantom and in vivo brain experiments show that 83–100% of the PRESS SNR (metabolite-dependent) is achieved at under 75% of the SAR and 66% lower in-plane CSD. Conclusion The advantages of STEAM can be augmented with the higher SNR of PRESS by combining the spin and stimulated echoes. Quantification, especially of J-coupled resonances and intermediate and long TEs, must be carefully considered. PMID:24664399

  11. Studies on Nephrite and Jadeite Jades by Fourier Transform Infrared (ftir) and Raman Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Tan, T. L.; Ng, L. L.; Lim, L. C.

    2013-10-01

    The mineralogical properties of black nephrite jade from Western Australia are studied by Fourier transform infrared (FTIR) spectroscopy using both transmission and specular reflectance techniques in the 4000-400 cm-1 wavenumber region. The infrared absorption peaks in the 3700-3600 cm-1 region which are due to the O-H stretching mode provides a quantitative analysis of the Fe/(Fe+Mg) ratio in the mineral composition of jade samples. The Fe/(Fe+Mg) percentage in black nephrite is found to be higher than that in green nephrite, but comparable to that of actinolite (iron-rich nephrite). This implies that the mineralogy of black nephrite is closer to actinolite than tremolite. The jade is also characterized using Raman spectroscopy in the 1200-200 cm-1 region. Results from FTIR and Raman spectroscopic data of black nephrite jade are compared with those of green nephrite jade from New Zealand and jadeite jade from Myanmar. Black nephrite appears to have a slightly different chemical composition from green nephrite. Spectra from FTIR and Raman spectroscopic techniques were found to be useful in differentiating black nephrite, green nephrite, and green jadeite jades. Furthermore, data on refractive index, specific gravity, and hardness of black nephrite jade are measured and compared with those of green nephrite and of jadeite jade.

  12. Spectroscopic investigation on cocrystal formation between adenine and fumaric acid based on infrared and Raman techniques.

    PubMed

    Du, Yong; Fang, Hong Xia; Zhang, Qi; Zhang, Hui Li; Hong, Zhi

    2016-01-15

    As an important component of double-stranded DNA, adenine has powerful hydrogen-bond capability, due to rich hydrogen bond donors and acceptors existing within its molecular structure. Therefore, it is easy to form cocrystal between adenine and other small molecules with intermolecular hydrogen-bond effect. In this work, cocrystal of adenine and fumaric acid has been characterized as model system by FT-IR and FT-Raman spectral techniques. The experimental results show that the cocrystal formed between adenine and fumaric acid possesses unique spectroscopical characteristic compared with that of starting materials. Density functional theory (DFT) calculation has been performed to optimize the molecular structures and simulate vibrational modes of adenine, fumaric acid and the corresponding cocrystal. Combining the theoretical and experimental vibrational results, the characteristic bands corresponding to bending and stretching vibrations of amino and carbonyl groups within cocrystal are shifted into lower frequencies upon cocrystal formation, and the corresponding bond lengths show some increase due to the effect of intermolecular hydrogen bonding. Different vibrational modes shown in the experimental spectra have been assigned based on the simulation DFT results. The study could provide experimental and theoretical benchmarks to characterize cocrystal formed between active ingredients and cocrystal formers and also the intermolecular hydrogen-bond effect within cocrystal formation process by vibrational spectroscopic techniques.

  13. Spectroscopic investigation on cocrystal formation between adenine and fumaric acid based on infrared and Raman techniques

    NASA Astrophysics Data System (ADS)

    Du, Yong; Fang, Hong Xia; Zhang, Qi; Zhang, Hui Li; Hong, Zhi

    2016-01-01

    As an important component of double-stranded DNA, adenine has powerful hydrogen-bond capability, due to rich hydrogen bond donors and acceptors existing within its molecular structure. Therefore, it is easy to form cocrystal between adenine and other small molecules with intermolecular hydrogen-bond effect. In this work, cocrystal of adenine and fumaric acid has been characterized as model system by FT-IR and FT-Raman spectral techniques. The experimental results show that the cocrystal formed between adenine and fumaric acid possesses unique spectroscopical characteristic compared with that of starting materials. Density functional theory (DFT) calculation has been performed to optimize the molecular structures and simulate vibrational modes of adenine, fumaric acid and the corresponding cocrystal. Combining the theoretical and experimental vibrational results, the characteristic bands corresponding to bending and stretching vibrations of amino and carbonyl groups within cocrystal are shifted into lower frequencies upon cocrystal formation, and the corresponding bond lengths show some increase due to the effect of intermolecular hydrogen bonding. Different vibrational modes shown in the experimental spectra have been assigned based on the simulation DFT results. The study could provide experimental and theoretical benchmarks to characterize cocrystal formed between active ingredients and cocrystal formers and also the intermolecular hydrogen-bond effect within cocrystal formation process by vibrational spectroscopic techniques.

  14. Shape coexistence at low spin in the Z = 50 region and its spectroscopic signatures

    NASA Astrophysics Data System (ADS)

    Garrett, P. E.

    2016-08-01

    Nuclei in the Z = 50 region provide excellent examples of shape coexistence, the establishment of which occurred through the use of detailed spectroscopy, based not only on γ-ray spectroscopy but also conversion electron, particle transfer, Coulomb excitation, and lifetime measurements. The evidence to date strongly suggests that the presence of coexisting shapes arises from the promotion of protons across the Z = 50 closed shell and the strong correlations arising from interplay of the pairing and quadrupole interactions. The evidence for the presence of shape coexistence in the Z = 50 region, at low spin and low excitation energies, will be presented and clues for the microscopic origin explored.

  15. A Synthetic High-Spin Oxoiron(IV) Complex: Generation, Spectroscopic Characterization, and Reactivity

    SciTech Connect

    England, J.; Martinho, M; Farquhar, E; Frisch, J; Bominaar, E; Munck, E; Que, L

    2009-01-01

    The high-yield generation of a synthetic high-spin oxoiron(IV) complex, (Fe{sup IV}(O)(TMG{sub 3}tren)){sup 2+} (TMG{sub 3}tren = 1,1,1-tris{l_brace}2-(N2-(1,1,3,3-tetramethylguanidino))ethyl{r_brace}amine), has been achieved by using the very bulky tetradentate TMG{sub 3}tren ligand, in order to both sterically protect the oxoiron(IV) moiety and enforce a trigonal bipyramidal geometry at the iron center, for which an S=2 ground state is favored.

  16. Investigation of effect of annealing on thermally evaporated ZnSe thin films through spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Mahesha, M. G.; Rashmitha; Meghana, N.; Padiyar, Meghavarsha

    2017-09-01

    ZnSe thin films have been grown on clean glass substrates by thermal evaporation technique and deposited films have been annealed at 473 K. William-Hall method has been adopted to extract information on crystallite size and internal strain in the film from X-ray diffractogram. Effect of annealing on ZnSe films has been analyzed by spectroscopic techniques which include optical absorption, Raman, and photoluminescence spectroscopy. From optical absorption, band gap has been estimated along with other optical parameters like refractive index and extinction coefficient. Also, Urbach tail, which originates near bad edge due to structural disorders, has been characterized. Raman spectra have been analyzed to get the information on the influence of crystallite size and strain effect on peak position, intensity and width. Photoluminescence spectra have been recorded and analyzed to get an insight on defect levels induced due to vacancies, interstadials, and impurity complexes.

  17. Implementation of Multiple Spectroscopic Techniques to Simultaneously Observe Native and Mutated Protein Unfolding

    NASA Astrophysics Data System (ADS)

    Cull, Brennan; Ben, Kelty; Link, Justin

    A protein's natural, correctly folded structure can determine the protein's ability to carry out its function. If the unfolding process of proteins can be observed, then the relative stability can be better understood between native and mutated proteins. A global picture of the unfolding process may be completed through the studies of strategically mutated proteins using tryptophan as a probe. Horse heart cytochrome c, a thoroughly studied, model protein was used in our investigation to explore this idea. Various spectroscopic techniques such as circular dichroism (CD), absorbance, and fluorescence were simultaneously applied while slowly unfolding our protein by increasing the concentration of a chemical denaturant, guanidine hydrochloride. This provided us information about the thermodynamic properties of the protein and several mutants which can then be interpreted to gain relative stability information among mutations. Efforts to utilize these techniques on native and mutated proteins in comparison to current scientific unfolding theories will be presented in this session.

  18. Assessment of amsacrine binding with DNA using UV-visible, circular dichroism and Raman spectroscopic techniques.

    PubMed

    Jangir, Deepak Kumar; Dey, Sanjay Kumar; Kundu, Suman; Mehrotra, Ranjana

    2012-09-03

    Proper understanding of the mechanism of binding of drugs to their targets in cell is a fundamental requirement to develop new drug therapy regimen. Amsacrine is a rationally designed anticancer drug, used to treat leukemia and lymphoma. Binding with cellular DNA is a crucial step in its mechanism of cytotoxicity. Despite numerous studies, DNA binding properties of amsacrine are poorly understood. Its reversible binding with DNA does not permit X-ray crystallography or NMR spectroscopic evaluation of amsacrine-DNA complexes. In the present work, interaction of amsacrine with calf thymus DNA is investigated at physiological conditions. UV-visible, FT-Raman and circular dichroism spectroscopic techniques were employed to determine the binding mode, binding constant, sequence specificity and conformational effects of amsacrine binding to native calf thymus DNA. Our results illustrate that amsacrine interacts with DNA by and large through intercalation between base pairs. Binding constant of the amsacrine-DNA complex was found to be K=1.2±0.1×10(4) M(-1) which is indicative of moderate type of binding of amsacrine to DNA. Raman spectroscopic results suggest that amsacrine has a binding preference of intercalation between AT base pairs of DNA. Minor groove binding is also observed in amsacrine-DNA complexes. These results are in good agreement with in silico investigation of amsacrine binding to DNA and thus provide detailed insight into DNA binding properties of amsacrine, which could ultimately, renders its cytotoxic efficacy. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Spectroscopic Evidence for Strong Quantum Spin Fluctuations with Itinerant Character in YFe2Ge2

    DOE PAGES

    Sirica, N.; Bondino, F.; Nappini, S.; ...

    2015-03-04

    We report x-ray absorption and photoemission spectroscopy of the electronic structure in the normal state of metallic YFe2Ge2. The data reveal evidence for large fluctuating spin moments on the Fe sites, as indicated by exchange multiplets appearing in the Fe 3s core-level photoemission spectra, even though the compound does not show magnetic order. The magnitude of the multiplet splitting is comparable to that observed in the normal state of the Fe-pnictide superconductors. This shows a connection between YFe2Ge2 and the Fe-based superconductors even though it contains neither pnictogens nor chalcogens. Finally, the implication is that the chemical range of compoundsmore » showing at least one of the characteristic magnetic signatures of the Fe-based superconductors is broader than previously thought.« less

  20. Unravel the interaction of protoporphyrin IX with reduced graphene oxide by vital spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Jhonsi, Mariadoss Asha; Nithya, Chandrasekaran; Kathiravan, Arunkumar

    2017-05-01

    Probing interaction between dyes and reduced graphene oxide (rGO) is of contemporary research interest. Since, rGO is widely used as electron acceptor in photovoltaic and optoelectronic devices. Hence, we have investigated the interaction between protoporphyrin IX (PPIX) and rGO by vital spectroscopic techniques. The adsorption of PPIX on rGO is studied by Attenuated total reflection-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopic (XPS) measurements. The fluorescence quenching measurements are also performed and the fluorescence intensity of PPIX is quenched by rGO. The quenching of PPIX with rGO is evaluated by the Stern-Volmer equation and time-resolved fluorescence lifetime studies. The results revealed that the fluorescence quenching of PPIX with rGO is due to the static quenching mechanism. The dominant process for this quenching has been attributed to the process of electron transfer from excited state PPIX to rGO. Fluorescence lifetime measurements were used to calculate the rate of electron transfer process between excited state of PPIX and rGO. Transient absorption studies demonstrated the formation of PPIX cation radical for the evidence of electron transfer between PPIX and rGO.

  1. Spin-echo magnetic resonance spectroscopic imaging at 7 T with frequency-modulated refocusing pulses.

    PubMed

    Zhu, He; Soher, Brian J; Ouwerkerk, Ronald; Schär, Michael; Barker, Peter B

    2013-05-01

    Two approaches to high-resolution SENSE-encoded magnetic resonance spectroscopic imaging (MRSI) of the human brain at 7 Tesla (T) with whole-slice coverage are described. Both sequences use high-bandwidth radiofrequency pulses to reduce chemical shift displacement artifacts, SENSE-encoding to reduce scan time, and dual-band water and lipid suppression optimized for 7 T. Simultaneous B0 and transmit B1 mapping was also used for both sequences to optimize field homogeneity using high-order shimming and determine optimum radiofrequency transmit level, respectively. One sequence ("Hahn-MRSI") used reduced flip angle (90°) refocusing pulses for lower radiofrequency power deposition, while the other sequence used adiabatic fast passage refocusing pulses for improved sensitivity and reduced signal dependence on the transmit-B1 level. In four normal subjects, adiabatic fast passage-MRSI showed a signal-to-noise ratio improvement of 3.2±0.5 compared to Hahn-MRSI at the same spatial resolution, pulse repetition time, echo time, and SENSE-acceleration factor. An interleaved two-slice Hahn-MRSI sequence is also demonstrated to be experimentally feasible.

  2. Diffusion of oxygen in water and hydrocarbons using an electron spin resonance spin-label technique.

    PubMed Central

    Subczynski, W K; Hyde, J S

    1984-01-01

    The Smoluchowski equation for the bimolecular collision rate of dissolved oxygen molecules with spin labels yielded values for the diffusion constant of oxygen in water that are in agreement with the Stokes-Einstein equation (D infinity T/eta, where eta is the macroscopic viscosity) and with published values obtained by conventional methods. Heisenberg exchange at an interaction distance of 4.5 A occurs with a probability close to one for each encounter. In mixed hydrocarbons (olive oil, paraffin oils) and sec-butyl benzene, D infinity (T/eta)rho, where rho lies between 0.5 and 1. Oxygen diffuses in the hydrocarbons between 10 and 100 times more rapidly than predicted from the macroscopic viscosity. Similar results would be expected for diffusion of oxygen in model and biological membranes. Parallel measurements of rotational diffusion of the spin labels show little correlation with measurements of translational diffusion of oxygen. Dipolar interactions between spin labels and oxygen appear negligible except in the limit of highest viscosities. PMID:6326877

  3. Characterizing Si:P quantum dot qubits with spin resonance techniques

    PubMed Central

    Wang, Yu; Chen, Chin-Yi; Klimeck, Gerhard; Simmons, Michelle Y.; Rahman, Rajib

    2016-01-01

    Quantum dots patterned by atomically precise placement of phosphorus donors in single crystal silicon have long spin lifetimes, advantages in addressability, large exchange tunability, and are readily available few-electron systems. To be utilized as quantum bits, it is important to non-invasively characterise these donor quantum dots post fabrication and extract the number of bound electron and nuclear spins as well as their locations. Here, we propose a metrology technique based on electron spin resonance (ESR) measurements with the on-chip circuitry already needed for qubit manipulation to obtain atomic scale information about donor quantum dots and their spin configurations. Using atomistic tight-binding technique and Hartree self-consistent field approximation, we show that the ESR transition frequencies are directly related to the number of donors, electrons, and their locations through the electron-nuclear hyperfine interaction. PMID:27550779

  4. Characterizing Si:P quantum dot qubits with spin resonance techniques.

    PubMed

    Wang, Yu; Chen, Chin-Yi; Klimeck, Gerhard; Simmons, Michelle Y; Rahman, Rajib

    2016-08-23

    Quantum dots patterned by atomically precise placement of phosphorus donors in single crystal silicon have long spin lifetimes, advantages in addressability, large exchange tunability, and are readily available few-electron systems. To be utilized as quantum bits, it is important to non-invasively characterise these donor quantum dots post fabrication and extract the number of bound electron and nuclear spins as well as their locations. Here, we propose a metrology technique based on electron spin resonance (ESR) measurements with the on-chip circuitry already needed for qubit manipulation to obtain atomic scale information about donor quantum dots and their spin configurations. Using atomistic tight-binding technique and Hartree self-consistent field approximation, we show that the ESR transition frequencies are directly related to the number of donors, electrons, and their locations through the electron-nuclear hyperfine interaction.

  5. In Vivo EPR Resolution Enhancement Using Techniques Known from Quantum Computing Spin Technology.

    PubMed

    Rahimi, Robabeh; Halpern, Howard J; Takui, Takeji

    2017-01-01

    A crucial issue with in vivo biological/medical EPR is its low signal-to-noise ratio, giving rise to the low spectroscopic resolution. We propose quantum hyperpolarization techniques based on 'Heat Bath Algorithmic Cooling', allowing possible approaches for improving the resolution in magnetic resonance spectroscopy and imaging.

  6. Study on the interaction between Besifloxacin and bovine serum albumin by spectroscopic techniques.

    PubMed

    Yu, Xianyong; Jiang, Bingfei; Liao, Zhixi; Jiao, Yue; Yi, Pinggui

    2015-01-01

    The interaction between Besifloxacin (BFLX) and bovine serum albumin (BSA) was investigated by spectroscopic (fluorescence, UV-Vis absorption and circular dichroism) techniques under imitated physiological conditions. The experiments were conducted at different temperatures (298, 304 and 310 K) and the results showed that the BFLX caused the fluorescence quenching of BSA through a static quenching procedure. The binding constant (Ka), binding sites (n) were obtained. The corresponding thermodynamic parameters (ΔH, ΔS and ΔG) of the interaction system were calculated at different temperatures. The results revealed that the binding process was spontaneous and the acting force between BFLX and BSA were mainly electrostatic forces. According to Förster non-radiation energy transfer theory, the binding distance between BFLX and BSA was calculated to be 4.96 nm. What is more, both synchronous fluorescence and circular dichroism spectra confirmed conformational changes of BSA.

  7. Dielectric studies of boron sub phthalocyanine chloride thin films by admittance spectroscopic techniques

    SciTech Connect

    Kalia, Sameer; Neerja; Mahajan, Aman Sharma, Anshul Kumar; Kumar, Sanjeev; Bedi, R. K.

    2016-05-06

    The dielectric properties of Boron Sub Phthalocyanine Chloride (Cl-SubPc) thermally deposited on ITO substrate have been studied using admittance spectroscopic techniques. The I-V and capacitance –frequency (C-F) studies at various bias voltages reveal that the mobility of charge carriers decrease with bias voltage, however the conduction phenomenon still remain hopping in nature. From the differential susceptance curve, the contribution of the Schottky barrier contact in the charge carrier concentration was found to be absent. The mobility of charge carriers have been determined using differential susceptance variation and from the phase of admittance curve. The values obtained in two cases have been found to be in agreement with each other.

  8. Systematic toxicological analysis of drugs and poisons in biosamples by hyphenated chromatographic and spectroscopic techniques.

    PubMed

    Polettini, A

    1999-10-15

    The introduction of hyphenated chromatographic-spectroscopic techniques represented a substantial step-forward for Systematic Toxicological Analysis (STA), increasing the amount and quality of information obtainable from the analysis of a biological sample, and enhancing the possibilities of identifying unknown drugs and poisons. STA methods based either on GC-MS or on HPLC-UV published in the last decade are reviewed in this paper. The different analytical phases, i.e. sample preparation (pretreatment, extraction, derivatisation), chromatographic separation and detection/identification are examined in detail in order to emphasise the complementarity of the two approaches. In addition, the first STA method based on HPLC-MS is illustrated and some applications of TLC-UV to drug screening are also described. Finally, an overview of semi- and fully-automated STA methods is given.

  9. Spectroscopic study of floating zone technique-grown Nd3+-doped CaMoO4

    NASA Astrophysics Data System (ADS)

    Andrade, L. H. C.; Reyes Ardila, D.; Barbosa, L. B.; Andreeta, J. P.; Li, M. Siu; Brenier, A.; Guyot, Y.; Boulon, G.

    2005-01-01

    Optical spectroscopy studies of Nd3+-doped scheelite calcium molybdate (CaMoO{4}) single crystal grown by a floating zone-like technique was performed using Judd-Ofelt analysis, besides luminescence data and lifetime measurements in the visible and near infrared domains. The excited state absorption in cross section units of this material was measured by two different methods for all expected infrared emission. By using calculated intensity parameters Ω t (t=2, 4, 6), it were determined branching ratios, emission cross-sections, and lifetimes for all related transitions. The observed single excited state absorption calibrated in absorption cross-section units was found too small to disturb the laser efficiency in the 1030 1100 nm spectral range. A comparison of main spectroscopic parameters of this material with those of other Nd3+-doped crystals is presented.

  10. Thiourea recognition by 2,6-bis(2-benzimidazolyl)pyridine using spectroscopic techniques and DFT

    NASA Astrophysics Data System (ADS)

    Chetia, Bolin; Goutam, Prasanta J.; Chipem, Francis A. S.; Iyer, Parameswar K.

    2013-06-01

    Recognition of thiourea by 2,6-bis(2-benzimidazolyl)pyridine, bbp, a neutral tridentate ligand was studied by UV visible and fluorescence spectroscopic techniques. FTIR spectroscopy and supportive DFT calculations established that, thiourea molecule, while bound to the binding site of bbp took up a near perpendicular orientation to the plane of the receptor. While forming the complex, the two imidazole H atoms present in the binding site of bbp formed two weak interactions with S atom of thiourea, which has low electronegativity. Moreover, bigger size of S atom restricted approach of thiourea inside the binding site. Stability of the bbp:thiourea complex basically increased as one of the imine H atom of thiourea is involved in a hydrogen bond with the pyridine N atom of bbp, which forced the near perpendicular orientation of thiourea on the plane of bbp. This binding mode is significantly different from the binding mode of urea with bbp as reported earlier.

  11. Electron Spin Resonance and optical absorption spectroscopic studies of manganese centers in aluminium lead borate glasses.

    PubMed

    SivaRamaiah, G; LakshmanaRao, J

    2012-12-01

    Electron Spin Resonance (ESR) and optical absorption studies of 5Al(2)O(3)+75H(3)BO(3)+(20-x)PbO+xMnSO(4) (where x=0.5, 1,1.5 and 2 mol% of MnSO(4)) glasses at room temperature have been studied. The ESR spectrum of all the glasses exhibits resonance signals with effective isotropic g values at ≈2.0, 3.3 and 4.3. The ESR resonance signal at isotropic g≈2.0 has been attributed to Mn(2+) centers in an octahedral symmetry. The ESR resonance signals at isotropic g≈3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn(2+) ions. The zero-field splitting parameter (zfs) has been calculated from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits an intense band in the visible region and it has been attributed to (5)E(g)→(5)T(2g) transition of Mn(3+)centers in an octahedral environment. The optical band gap and the Urbach energies have been calculated from the ultraviolet absorption edges.

  12. Infrared spectroscopic investigation of nuclear spin conversion in solid CH{sub 4}

    SciTech Connect

    Sugimoto, Takeru; Yamakawa, Koichiro Arakawa, Ichiro

    2015-12-14

    Infrared spectra of solid CH{sub 4} were studied in the ν{sub 3} and ν{sub 4} vibrational regions. The phase I crystal around 30 K showed broad absorption bands, whereas the phase II crystal at 6.9–10.3 K exhibited splitting of these bands after annealing above 20 K. The split peaks were assigned to the librating and almost freely rotating molecules in phase II on the basis of the peak spacings and time evolution of the peak intensities. From the quantitative analysis of the temporal changes of the R(0) and R(1) peak intensities, the relaxation rates of the numbers of molecules with J = 0 (I = 2) and J = 1 (I = 1) were determined in the temperature range of 6.9–10.3 K. We fitted the function resulting from a combination of direct and indirect relaxation processes mediated by phonons to the temperature dependence of these rates and obtained the activation energies of the indirect process: C ≃ 36 K. Since this value is higher than the energies of perturbed J = 2 states relative to the J = 1 state, we argue that the nuclear spin conversion through the J = 3 state also takes place.

  13. Infrared spectroscopic investigation of nuclear spin conversion in solid CH4

    NASA Astrophysics Data System (ADS)

    Sugimoto, Takeru; Yamakawa, Koichiro; Arakawa, Ichiro

    2015-12-01

    Infrared spectra of solid CH4 were studied in the ν3 and ν4 vibrational regions. The phase I crystal around 30 K showed broad absorption bands, whereas the phase II crystal at 6.9-10.3 K exhibited splitting of these bands after annealing above 20 K. The split peaks were assigned to the librating and almost freely rotating molecules in phase II on the basis of the peak spacings and time evolution of the peak intensities. From the quantitative analysis of the temporal changes of the R(0) and R(1) peak intensities, the relaxation rates of the numbers of molecules with J = 0 (I = 2) and J = 1 (I = 1) were determined in the temperature range of 6.9-10.3 K. We fitted the function resulting from a combination of direct and indirect relaxation processes mediated by phonons to the temperature dependence of these rates and obtained the activation energies of the indirect process: C ≃ 36 K. Since this value is higher than the energies of perturbed J = 2 states relative to the J = 1 state, we argue that the nuclear spin conversion through the J = 3 state also takes place.

  14. Development of a low resolution (1)H NMR spectroscopic technique for the study of matrix mobility in fresh and freeze-thawed hen egg yolk.

    PubMed

    Au, Carmen; Wang, Tong; Acevedo, Nuria C

    2016-08-01

    Three experiments were conducted in developing a low resolution proton nuclear magnetic resonance ((1)H NMR) spectroscopic technique to study matrix mobility in fresh and freeze-thawed gelled yolk. The Carr-Purcell-Meiboom-Gill (CPMG) sequence was used to measure spin-spin relaxation times of proton pools representing major yolk constituents. A component identification test distinguished 3-4 pools. The least mobile pool was assigned to proteins, protein-lipid and protein-water interactions, and the most mobile to unbound water. The remaining pools were assigned to lipids, lipid-protein and lipid-water interactions. A stability test indicated that yolk had varied matrix mobility within the same sample across five days of refrigeration storage. A reproducibility test demonstrated high repeatability of fresh yolk measurements, but significant differences (p<0.05) were found within gelled yolk samples. This research determined that (1)H NMR spectroscopy, a non-destructive technique, can identify yolk components and detect changes in the matrix. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Nondestructive spectroscopic and imaging techniques for quality evaluation and assessment of fish and fish products.

    PubMed

    He, Hong-Ju; Wu, Di; Sun, Da-Wen

    2015-01-01

    Nowadays, people have increasingly realized the importance of acquiring high quality and nutritional values of fish and fish products in their daily diet. Quality evaluation and assessment are always expected and conducted by using rapid and nondestructive methods in order to satisfy both producers and consumers. During the past two decades, spectroscopic and imaging techniques have been developed to nondestructively estimate and measure quality attributes of fish and fish products. Among these noninvasive methods, visible/near-infrared (VIS/NIR) spectroscopy, computer/machine vision, and hyperspectral imaging have been regarded as powerful and effective analytical tools for fish quality analysis and control. VIS/NIR spectroscopy has been widely applied to determine intrinsic quality characteristics of fish samples, such as moisture, protein, fat, and salt. Computer/machine vision on the other hand mainly focuses on the estimation of external features like color, weight, size, and surface defects. Recently, by incorporating both spectroscopy and imaging techniques in one system, hyperspectral imaging cannot only measure the contents of different quality attributes simultaneously, but also obtain the spatial distribution of such attributes when the quality of fish samples are evaluated and measured. This paper systematically reviews the research advances of these three nondestructive optical techniques in the application of fish quality evaluation and determination and discuss future trends in the developments of nondestructive technologies for further quality characterization in fish and fish products.

  16. Recent developments in spectroscopic imaging techniques for historical paintings - A review

    NASA Astrophysics Data System (ADS)

    Alfeld, M.; de Viguerie, L.

    2017-10-01

    This paper provides an overview over the application of scanning macro-XRF with mobile instruments for the investigation of historical paintings. The method is compared to synchrotron based macro-XRF imaging and Neutron Activation Auto-Radiography. Full-Field XRF imaging instruments, a potential future alternative to scanning macro-XRF, and confocal XRF, providing complementary depth profiles and developing into a 3D imaging technique itself, are described with the focus on investigations of historical paintings. Recent developments of X-ray radiography are presented and the investigation of cultural heritage objects other than paintings by MA-XRF is summarized. In parallel to XRF, hyperspectral imaging in the visible and range has developed into a technique with comparable capabilities, providing insight in chemical compounds, where XRF imaging identifies the distribution of elements. Due to the complementary nature of these techniques the latter is summarized. Further, progress and state of the art in data evaluation for spectroscopic imaging is discussed. In general it could be observed that technical capabilities in MA-XRF and hyperspectral imaging have reached a plateau and that with the availability of commercial instruments the focus of recent studies has shifted from the development of methods to applications of the instruments. Further, that while simple instruments are easily available with medium budgets only few groups have high-end instrumentation available, bought or in-house built.

  17. Study on the interaction of catechins with human serum albumin using spectroscopic and electrophoretic techniques

    NASA Astrophysics Data System (ADS)

    Trnková, Lucie; Boušová, Iva; Staňková, Veronika; Dršata, Jaroslav

    2011-01-01

    The interaction between eight naturally occurring flavanols (catechin, epicatechin, gallocatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, and epigallocatechin gallate) and human serum albumin (HSA) has been investigated by spectroscopic (fluorescence quenching and UV-Vis absorption) and electrophoretic (native and SDS PAGE) techniques under simulated physiological conditions (pH 7.40, 37 °C). The spectroscopic results confirmed the complex formation for the tested systems. The binding constants and the number of binding sites were obtained by analysis of fluorescence data. The strongest binding affinity to HSA was found for epicatechin gallate and decreased in the order epicatechin gallate ⩾ catechin gallate > epigallocatechin gallate > gallocatechin gallate ≫ epicatechin ⩾ catechin > gallocatechin ⩾ epigallocatechin. All free energy changes possessed negative sign indicating the spontaneity of catechin-HSA systems formation. The binding distances between the donor (HSA) and the acceptors (catechins) estimated by the Förster theory revealed that non-radiation energy transfer from HSA to catechins occurred with high possibility. According to results obtained by native PAGE, the galloylated catechins increased the electrophoretic mobility of HSA, which indicated the change in the molecular charge of HSA, whilst the non-galloylated catechins caused no changes. The ability of aggregation and cross-linking of tested catechins with HSA was not proved by SDS-PAGE. The relationship between the structure characteristics of all tested catechins (e.g. presence of the galloyl moiety on the C-ring, the number of hydroxyl groups on the B-ring, and the spatial arrangement of the substituents on the C-ring) and their binding properties to HSA is discussed. The presented study contributes to the current knowledge in the area of protein-ligand binding, particularly catechin-HSA interactions.

  18. Intratumoral Agreement of High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopic Profiles in the Metabolic Characterization of Breast Cancer

    PubMed Central

    Park, Vivian Youngjean; Yoon, Dahye; Koo, Ja Seung; Kim, Eun-Kyung; Kim, Seung Il; Choi, Ji Soo; Park, Seho; Park, Hyung Seok; Kim, Suhkmann; Kim, Min Jung

    2016-01-01

    Abstract High-resolution magic angle spinning (HR-MAS) magnetic resonance (MR) spectroscopy data may serve as a biomarker for breast cancer, with only a small volume of tissue sample required for assessment. However, previous studies utilized only a single tissue sample from each patient. The aim of this study was to investigate whether intratumoral location and biospecimen type affected the metabolic characterization of breast cancer assessed by HR-MAS MR spectroscopy This prospective study was approved by the institutional review board and informed consent was obtained. Preoperative core-needle biopsies (CNBs), central, and peripheral surgical tumor specimens were prospectively collected under ultrasound (US) guidance in 31 patients with invasive breast cancer. Specimens were assessed with HR-MAS MR spectroscopy. The reliability of metabolite concentrations was evaluated and multivariate analysis was performed according to intratumoral location and biospecimen type. There was a moderate or higher agreement between the relative concentrations of 94.3% (33 of 35) of metabolites in the center and periphery, 80.0% (28 of 35) of metabolites in the CNB and central surgical specimens, and 82.9% (29 of 35) of metabolites between all 3 specimen types. However, there was no significant agreement between the concentrations of phosphocholine (PC) and phosphoethanolamine (PE) in the center and periphery. The concentrations of several metabolites (adipate, arginine, fumarate, glutamate, PC, and PE) had no significant agreement between the CNB and central surgical specimens. In conclusion, most HR-MAS MR spectroscopic data do not differ based on intratumoral location or biospecimen type. However, some metabolites may be affected by specimen-related variables, and caution is recommended in decision-making based solely on metabolite concentrations, particularly PC and PE. Further validation through future studies is needed for the clinical implementation of these biomarkers based

  19. Application of spectroscopic techniques for the analysis of kidney stones: a pilot study

    NASA Astrophysics Data System (ADS)

    Shameem, K. M., Muhammed; Chawla, Arun; Bankapur, Aseefhali; Unnikrishnan, V. K.; Santhosh, C.

    2016-03-01

    Identification and characterization of kidney stone remains one of the important analytical tasks in the medical field. Kidney stone is a common health complication throughout the world, which may cause severe pain, obstruction and infection of urinary tract, and can lead to complete renal damage. It commonly occurs in both sexes regardless of age. Kidney stones have different composition, although each stones have a major single characteristic component. A complete understanding of a sample properties and their function can only be feasible by utilizing elemental and molecular information simultaneously. Two laser based analytical techniques; Laser Induced Breakdown spectroscopy (LIBS) and Raman spectroscopy have been used to study different types of kidney stones from different patients. LIBS and Raman spectroscopy are highly complementary spectroscopic techniques, which provide elemental and molecular information of a sample. Q-switched Nd:YAG laser at 355 nm laser having energy 17mJ per pulse at 10 Hz repetition rate was used for getting LIBS spectra. Raman measurements were carried out using a home assembled micro-Raman spectrometer. Using the recorded Raman spectra of kidney stones, we were able to differentiate different kinds of kidney stones. LIBS spectra of the same stones are showing the evidence of C, Ca, H, and O and also suggest the presence of certain pigments.

  20. A RAPID SPECTROSCOPIC TECHNIQUE FOR DETERMINING THE POTENTIAL ALPHA ENERGY CONCENTRATION OF RADON DECAY PRODUCTS

    SciTech Connect

    Revzan, K. L.; Nazaroff, W. W.

    1981-07-01

    We consider the application of alpha spectroscopy to the rapid determination of the potential alpha energy concentration (PAEC) of radon decay products indoors. Two count totals are obtained after a single counting period. The PAEC is then estimated by a linear combination of the count totals, the two coefficients being determined by analysis of the dependence of the statistical and procedural errors on the equilibrium conditions and the sampling, delay, and counting times. For a total measurement time of 11 min, the procedural error is unlikely to exceed 20% for equilibrium conditions commonly found indoors; the statistical error is less than 20% at a PAEC of 0.005 WL, assuming a product of detector efficiency and flow rate of at least 1.0 l/min. An analysis is made of techniques based on a total alpha count, and the results are compared with those obtained with the rapid spectroscopic technique; the latter is clearly preferable when the measurement time does not exceed 15 min.

  1. DNA-binding study of anticancer drug cytarabine by spectroscopic and molecular docking techniques.

    PubMed

    Shahabadi, Nahid; Falsafi, Monireh; Maghsudi, Maryam

    2017-01-02

    The interaction of anticancer drug cytarabine with calf thymus DNA (CT-DNA) was investigated in vitro under simulated physiological conditions by multispectroscopic techniques and molecular modeling study. The fluorescence spectroscopy and UV absorption spectroscopy indicated drug interacted with CT-DNA in a groove-binding mode, while the binding constant of UV-vis and the number of binding sites were 4.0 ± 0.2 × 10(4) L mol(-1) and 1.39, respectively. The fluorimetric studies showed that the reaction between the drugs with CT-DNA is exothermic. Circular dichroism spectroscopy was employed to measure the conformational change of DNA in the presence of cytarabine. Furthermore, the drug induces detectable changes in its viscosity for DNA interaction. The molecular modeling results illustrated that cytarabine strongly binds to groove of DNA by relative binding energy of docked structure -20.61 KJ mol(-1). This combination of multiple spectroscopic techniques and molecular modeling methods can be widely used in the investigation on the interaction of small molecular pollutants and drugs with biomacromolecules for clarifying the molecular mechanism of toxicity or side effect in vivo.

  2. The Spin Move: A Reliable and Cost-Effective Gowning Technique for the 21st Century.

    PubMed

    Ochiai, Derek H; Adib, Farshad

    2015-04-01

    Operating room efficiency (ORE) and utilization are considered one of the most crucial components of quality improvement in every hospital. We introduced a new gowning technique that could optimize ORE. The Spin Move quickly and efficiently wraps a surgical gown around the surgeon's body. This saves the operative time expended through the traditional gowning techniques. In the Spin Move, while the surgeon is approaching the scrub nurse, he or she uses the left heel as the fulcrum. The torque, which is generated by twisting the right leg around the left leg, helps the surgeon to close the gown as quickly and safely as possible. From 2003 to 2012, the Spin Move was performed in 1,725 consecutive procedures with no complication. The estimated average time was 5.3 and 7.8 seconds for the Spin Move and traditional gowning, respectively. The estimated time saving for the senior author during this period was 71.875 minutes. Approximately 20,000 orthopaedic surgeons practice in the United States. If this technique had been used, 23,958 hours could have been saved. The money saving could have been $14,374,800.00 (23,958 hours × $600/operating room hour) during the past 10 years. The Spin Move is easy to perform and reproducible. It saves operating room time and increases ORE.

  3. A technique for measurement of vector and tensor polarization in solid spin one polarized targets

    SciTech Connect

    Kielhorn, W.F.

    1991-06-01

    Vector and tensor polarizations are explicitly defined and used to characterize the polarization states of spin one polarized targets, and a technique for extracting these polarizations from nuclear magnetic resonance (NMR) data is developed. This technique is independent of assumptions about spin temperature, but assumes the target's crystal structure induces a quadrupole interaction with the spin one particles. Analysis of the NMR signals involves a computer curve fitting algorithm implemented with a fast Fourier transform method which speeds and simplifies curve fitting algorithms used previously. For accurate curve fitting, the NMR electronic circuit must be modeled by the fitting algorithm. Details of a circuit, its model, and data collected from this circuit are given for a solid deuterated ammonia target. 37 refs., 19 figs., 3 tabs.

  4. Mineralogical Characterization Studies on Unburnt Ceramic Product Made from Rock Residue Additives by Ft-Ir Spectroscopic Technique

    NASA Astrophysics Data System (ADS)

    Vijayaragavan, R.; Mullainathan, S.; Balachandramohan, M.; Krishnamoorthy, N.; Nithiyanantham, S.; Murugesan, S.; Vanathi, V.

    2013-10-01

    The usability of waste rock (rock residue) powder as an additive material in ceramic samples was investigated. Qualitative analysis was carried out to determine the major and minor constituent minerals present in ceramic bodies made from rock residue powder by using FT-IR spectroscopic technique. Further, the representative ceramic bodies are analyzed by FT-IR technique to yield more information about the functional groups and also to estimate the order or disorder of kaolinite structure.

  5. Planetary Surface Analysis Using Fast Laser Spectroscopic Techniques: Combined Microscopic Raman, LIBS, and Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Blacksberg, J.; Rossman, G. R.; Maruyama, Y.; Charbon, E.

    2011-12-01

    In situ exploration of planetary surfaces has to date required multiple techniques that, when used together, yield important information about their formation histories and evolution. We present a time-resolved laser spectroscopic technique that could potentially collect complementary sets of data providing information on mineral structure, composition, and hydration state. Using a picosecond-scale pulsed laser and a fast time-resolved detector we can simultaneously collect spectra from Raman, Laser Induced Breakdown Spectroscopy (LIBS), and fluorescence emissions that are separated in time due to the unique decay times of each process. The use of a laser with high rep rate (40 KHz) and low pulse energy (1 μJ/pulse) allows us to rapidly collect high signal to noise Raman spectra while minimizing sample damage. Increasing the pulse energy by about an order of magnitude creates a microscopic plasma near the surface and enables the collection of LIBS spectra at an unusually high rep rate and low pulse energy. Simultaneously, broader fluorescence peaks can be detected with lifetimes varying from nanosecond to microsecond. We will present Raman, LIBS, and fluorescence spectra obtained on natural mineral samples such as sulfates, clays, pyroxenes and carbonates that are of interest for Mars mineralogy. We demonstrate this technique using a photocathode-based streak camera detector as well as a newly-developed solid state Single Photon Avalanche Diode (SPAD) sensor array based on Complementary Metal-Oxide Semiconductor (CMOS) technology. We will discuss the impact of system design and detector choice on science return of a potential planetary surface mission, with a specific focus on size, weight, power, and complexity. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).

  6. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    SciTech Connect

    Wang, Xin

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  7. Spectroscopic technique with wide range of wavelength information improves near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Eda, Hideo; Aoki, Hiromichi; Eura, Shigeru; Ebe, Kazutoshi

    2009-02-01

    Near-infrared spectroscopy (NIRS) calculates hemoglobin parameters, such as oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) using the near-infrared light around the wavelength of 800nm. This is based on the modified-Lambert-Beer's law that changes in absorbance are proportional to changes in hemoglobin parameters. Many conventional measurement methods uses only a few wavelengths, however, in this research, basic examination of NIRS measurement was approached by acquiring wide range of wavelength information. Venous occlusion test was performed by using the blood pressure cuff around the upper arm. Pressure of 100mmHg was then applied for about 3 minutes. During the venous occlusion, the spectrum of the lower arm muscles was measured every 15 seconds, within the range of 600 to 1100nm. It was found that other wavelength bands hold information correlating to this venous occlusion task. Technique of improving the performance of NIRS measurement using the Spectroscopic Method is very important for Brain science.

  8. Qualitative and quantitative changes in phospholipids and proteins investigated by spectroscopic techniques in animal depression model

    NASA Astrophysics Data System (ADS)

    Depciuch, J.; Sowa-Kucma, M.; Nowak, G.; Papp, M.; Gruca, P.; Misztak, P.; Parlinska-Wojtan, M.

    2017-04-01

    Depression becomes nowadays a high mortality civilization disease with one of the major causes being chronic stress. Raman, Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-vis) spectroscopies were used to determine the changes in the quantity and structure of phospholipids and proteins in the blood serum of rats subjected to chronic mild stress, which is a common animal depression model. Moreover, the efficiency of the imipramine treatment was evaluated. It was found that chronic mild stress not only damages the structure of the phospholipids and proteins, but also decreases their level in the blood serum. A 5 weeks imipramine treatment did increase slightly the quantity of proteins, leaving the damaged phospholipids unchanged. Structural information from phospholipids and proteins was obtained by UV-vis spectroscopy combined with the second derivative of the FTIR spectra. Indeed, the structure of proteins in blood serum of stressed rats was normalized after imipramine therapy, while the impaired structure of phospholipids remained unaffected. These findings strongly suggest that the depression factor, which is chronic mild stress, may induce permanent (irreversible) damages into the phospholipid structure identified as shortened carbon chains. This study shows a possible new application of spectroscopic techniques in the diagnosis and therapy monitoring of depression.

  9. Soil examination for a forensic trace evidence laboratory--Part 1: Spectroscopic techniques.

    PubMed

    Woods, Brenda; Lennard, Chris; Kirkbride, K Paul; Robertson, James

    2014-12-01

    In the past, forensic soil examination was a routine aspect of trace evidence examination in forensic science. However, in Australia, the apparent need for soil examinations has diminished and with it the capability of forensic science laboratories to carry out soil examination has been eroded. In recent years, due to soil examinations contributing to some high profile investigations, interest in soil examinations has been renewed. Routine soil examinations conducted in a forensic science laboratory by trace evidence scientists can be facilitated if the examinations are conducted using the instrumentation routinely used by these examiners. Spectroscopic techniques such as visible microspectrophotometry (MSP) and Attenuated Total Reflectance (ATR) Fourier Transform Infrared spectroscopy (FTIR) are routinely used by trace evidence analysts for the colour and compositional analysis, respectively, of forensic items, including paints, fibres, inks and toners, tapes, adhesives and other miscellaneous examinations. This article presents an examination of the feasibility of using MSP and ATR-FTIR as a first step in the forensic comparison of soils with particular reference to Australian soil samples. This initial study demonstrates MSP and ATR-FTIR can effectively be used as a screening test for the discrimination of "forensic-sized" soil samples prior to submission for more detailed analyses by a soil expert. Crown Copyright © 2014. Published by Elsevier Ireland Ltd. All rights reserved.

  10. Investigation of fungal deterioration of synthetic paint binders using vibrational spectroscopic techniques.

    PubMed

    Cappitelli, Francesca; Vicini, Silvia; Piaggio, Paolo; Abbruscato, Pamela; Princi, Elisabetta; Casadevall, Arturo; Nosanchuk, Joshua D; Zanardini, Elisabetta

    2005-01-14

    The deterioration of synthetic polymers caused by biological process is usually evaluated by visual inspection and measuring physical effects. In contrast to this approach, we have applied vibrational spectroscopies to study the biodegradation of the synthetic resins. 29 synthetic resins used as paint binding media, including acrylic, alkyd and poly(vinyl acetate) polymers, were examined for potential susceptibility to fungal degradation using the standard method ASTM G21-96(2002). In addition, the degraded resins were analysed by Raman spectroscopy, FT-IR and FT-IR photoacoustic spectroscopy. Almost all the acrylic resins studied proved to be resistant to microbial attack, while all alkyd resins and some poly(vinyl acetates) turned out to be biodegradable. Within a few days of inoculation Aspergillus niger was the most copious fungus on the biodegraded resins. A comparison of the IR and Raman spectra of control and biodegraded resins did not show any differences, but photoacoustic spectroscopy revealed additional bands for the fungal-degraded resins, consistent with the presence of fungal-derived substances. The additional bands in the photoacoustic spectra were due to the presence of Aspergillus niger and melanin, a fungal pigment. Since IR photoacoustic spectroscopy can be also a suitable technique for the chemical characterisation of binding media, the same spectroscopic analysis can be employed to both characterise the material and obtain evidence for fungal colonization. Microbial growth on Sobral 1241ML (alkyd resin) after 28 d (growth rating 4) compared with the non-inoculated resin.

  11. Characterization of the binding of nevadensin to bovine serum albumin by optical spectroscopic technique

    NASA Astrophysics Data System (ADS)

    Yu, Zhaolian; Li, Daojin; Ji, Baoming; Chen, Jianjun

    2008-10-01

    Binding of nevadensin to bovine serum albumin (BSA) has been studied in detail at 298 and 310 K using spectrophotometric technique. The intrinsic fluorescence of BSA was strongly quenched by the addition of nevadensin and spectroscopic observations are mainly rationalized in terms of a static quenching process at lower concentration of nevadensin ( Cdrug/ CBSA < 1) and a combined quenching process at higher concentration of nevadensin ( Cdrug/ CBSA > 1). The binding parameters for the reaction at a pH above (7.40) or below (3.40) the isoelectric point have been calculated according to the double logarithm regression curve. The thermodynamic parameters Δ H0, Δ G0, Δ S0 at different temperatures and binding mechanism of nevadensin to BSA at pH 7.40 and 3.40 were evaluated. The binding ability of nevadensin to BSA at pH 7.40 was stronger than that at pH 3.40. Steady fluorescence, synchronous fluorescence and circular dichroism (CD) were applied to investigate protein conformation. A value of 2.15 nm for the average distance r between nevadensin (acceptor) and tryptophan residues (Trp) of BSA (donor) was derived from the fluorescence resonance energy transfer. Moreover, influence of pH on the interaction nevadensin with BSA was investigated.

  12. Integrated Analysis of the Wood Oil from Xanthocyparis vietnamensis Farjon & Hiep. by Chromatographic and Spectroscopic Techniques.

    PubMed

    Bazzali, Ophélie; Thai, Tran Huy; Hoi, Tran Minh; Khang, Nguyen Sinh; Hien, Nguyen Thi; Casanova, Joseph; Bighelli, Ange; Tomi, Félix

    2016-06-27

    In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC) and spectroscopic (GC-MS, (13)C-NMR) techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%), 11,12,13-tri-nor-eremophil-1(10)-en-7-one (17.2%), γ-eudesmol (5.1%), nootkatone (4.7%), valencene (3.5%) and 13-nor-eremophil-1(10)-en-11-one (2.6%). The structure of two new compounds-10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran-has been elucidated, while 11,12,13-tri-nor-eremophil-1(10)-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%), phyllocladene (37.8%) or by pimara-6(14)-15-diene (19.4%).

  13. Studies on the interaction of salvianolic acid B with human hemoglobin by multi-spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Chen, Tingting; Zhu, Shajun; Cao, Hui; Shang, Yanfang; Wang, Miao; Jiang, Guoqing; Shi, Yujun; Lu, Tianhong

    2011-04-01

    The interaction between salvianolic acid B (Sal B) and human hemoglobin (HHb) under physiological conditions was investigated by UV-vis absorption, fluorescence, synchronous fluorescence and circular dichroism spectroscopic techniques. The experimental results indicate that the quenching mechanism of fluorescence of HHb by Sal B is a static quenching procedure, the binding reaction is spontaneous, and the hydrophobic interactions play a major role in binding of Sal B to HHb. Based on Förster's theory of non-radiative energy transfer, the binding distance between Sal B and the inner tryptophan residues of HHb was determined to be 2.64 nm. The synchronous fluorescence experiment revealed that Sal B can not lead to the microenvironmental changes around the Tyr and Trp residues of HHb, and the binding site of Sal B on HHb is located at α 1β 2 interface of HHb. Furthermore, the CD spectroscopy indicated the secondary structure of HHb is not changed in the presence of Sal B.

  14. A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in radio frequency plasmas

    NASA Astrophysics Data System (ADS)

    Daksha, M.; Berger, B.; Schuengel, E.; Korolov, I.; Derzsi, A.; Koepke, M.; Donkó, Z.; Schulze, J.

    2016-06-01

    A computationally assisted spectroscopic technique to measure secondary electron emission coefficients (γ-CAST) in capacitively-coupled radio-frequency plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of phase resolved optical emission spectroscopy and particle-based kinetic simulations. In such plasmas (under most conditions in electropositive gases) the spatio-temporally resolved electron-impact excitation/ionization rate features two distinct maxima adjacent to each electrode at different times within each RF period. While one maximum is the consequence of the energy gain of electrons due to sheath expansion, the second maximum is produced by secondary electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the adjacent sheath. Due to these different excitation/ionization mechanisms, the ratio of the intensities of these maxima is very sensitive to the secondary electron emission coefficient γ. This sensitvity, in turn, allows γ to be determined by comparing experimental excitation profiles and simulation data obtained with various γ-coefficients. The diagnostic, tested here in a geometrically symmetric argon discharge, yields an effective secondary electron emission coefficient of γ =0.066+/- 0.01 for stainless steel electrodes.

  15. A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in technological rf plasmas

    NASA Astrophysics Data System (ADS)

    Berger, Birk; Schulze, Julian; Daksha, Manaswi; Schuengel, Edmund; Koepke, Mark; Korolov, Ihor; Derzsi, Aranka; Donko, Zoltan

    2016-09-01

    A Computationally Assisted Spectroscopic Technique to measure secondary electron emission coefficients (y-CAST) in capacitive rf plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of Phase Resolved Optical Emission Spectroscopy and PIC simulations. Under most conditions in electropositive plasmas the spatio-temporally resolved electron-impact excitation rate features two distinct maxima adjacent to each electrode at different times within one rf period. One maximum is the consequence of an energy gain of the electrons due to sheath expansion. The second maximum is produced by electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the sheath. Due to the different excitation mechanisms the ratio of the intensities of these maxima is very sensitive to y, which allows for its determination via comparing the experimentally measured excitation profiles with corresponding simulation data obtained with various y-coefficients. This diagnostic is tested here in a geometrically symmetric reactor, for stainless steel electrodes and argon gas. An effective secondary electron emission coefficient of y = 0.067+-0.010 is obtained, which is in excellent agreement with previous experimental results.

  16. Novel infrared spectroscopic techniques for the study of adsorbed proteins on photoactive thin films

    NASA Astrophysics Data System (ADS)

    Angle, Taylor Allan

    Through the development of attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopic techniques, as well as biocompatible nanoporous gold film confining layers and photoactive nanocrystal cadmium telluride (CdTe) thin films, a system capable of in situ study of adsorbed protein films on photoactive layers was created. Due to the oxygen intolerance of the enzyme of interest for this work (a [FeFe]-hydrogenase from Clostridium acetobutylicum), techniques were developed in a manner conducive to anaerobic environments. Solid-state ligand exchange processes were shown to have no detrimental effect on the continued ability of nanocrystal CdTe layers to reduce species via the transfer of photogenerated electrons. Nanoporous gold films were shown to effectively confine poorly bound surface species including nanocrystal CdTe layers and adsorbed protein films. An ATR "stack'' structure, consisting of a silicon wafer coupled to a zinc selenide ATR crystal by a high index optical coupling fluid, was designed and implemented, leading to a tunable optical structure for use with existing ATR setups. This ATR stack was shown to maintain resolution and signal intensity of traditional ATR configurations for both aqueous and solid-state samples. Through the use of coupled silicon wafers, we significantly increased both sample throughput and the number of available chemical processes by replacing the expensive ATR crystals as the default sample substrate. Shown herein to function as initially intended, these novel methods provide the groundwork for more complex experiments, such as an in situ monitoring of the photooxidation of surface-bound hydrogenases.

  17. Experimental Test of a New Technique to Overcome Spin-Depolarizing Resonances

    SciTech Connect

    Morozov, V. S.; Chao, A. W.; Krisch, A. D.; Leonova, M. A.; Raymond, R. S.; Sivers, D. W.; Wong, V. K.; Garishvili, A.; Gebel, R.; Lehrach, A.; Lorentz, B.; Maier, R.; Prasuhn, D.; Stockhorst, H.; Welsch, D.; Hinterberger, F.; Kondratenko, A. M.

    2009-06-19

    We recently tested a new spin resonance crossing technique, Kondratenko Crossing (KC), by sweeping an rf-solenoid's frequency through an rf-induced spin resonance with both the KC and traditional fast crossing (FC) patterns. Using both rf bunched and unbunched 1.85 GeV/c polarized deuterons stored in COSY, we varied the parameters of both crossing patterns. Compared to FC with the same crossing speed, KC reduced the depolarization by measured factors of 4.7+-0.3 and 19{sub -5}{sup +12} for unbunched and bunched beams, respectively. This clearly showed the large potential benefit of Kondratenko Crossing over fast crossing.

  18. Control-system techniques for improved departure/spin resistance for fighter aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, L. T.; Gilbert, W. P.; Ogburn, M. E.

    1980-01-01

    Some fundamental information on control system effects on controllability of highly maneuverable aircraft at high angles of attack are summarized as well as techniques for enhancing fighter aircraft departure/spin resistance using control system design. The discussion includes: (1) a brief review of pertinent high angle of attack phenomena including aerodynamics, inertia coupling, and kinematic coupling; (2) effects of conventional stability augmentation systems at high angles of attack; (3) high angle of attack control system concepts designed to enhance departure/spin resistance; and (4) the outlook for applications of these concepts to future fighters, particularly those designs which incorporate relaxed static stability.

  19. Continuous polymer nanofibers by extrusion into a viscous medium: A modified wet-spinning technique

    NASA Astrophysics Data System (ADS)

    Gorantla, M.; Boone, S. E.; El-Ashry, M.; Young, D.

    2006-02-01

    We present a wet-spinning technique capable of producing continuous polymer nanofibers. This method involves injecting a solvated polymer into a highly viscous moving medium through a microaperture. The extruded fiber moves in a predictable spiral path and is collected around a spinning mandrel which also serves to pull the extruded fiber away from the aperture. Semicontinuous, solid nanofibers of polyvinyl butyral were produced with diameters ranging from 10μmto400nm. Electron microscopy indicates that submicron fibers exhibit a ribbonlike morphology. The effect of different processing parameters on the fiber size and shape is discussed.

  20. Analysis of state-of-the-art single-thruster attitude control techniques for spinning penetrator

    NASA Astrophysics Data System (ADS)

    Raus, Robin; Gao, Yang; Wu, Yunhua; Watt, Mark

    2012-07-01

    The attitude dynamics and manoeuvre survey in this paper is performed for a mission scenario involving a penetrator-type spacecraft: an axisymmetric prolate spacecraft spinning around its minor axis of inertia performing a 90° spin axis reorientation manoeuvre. In contrast to most existing spacecraft only one attitude control thruster is available, providing a control torque perpendicular to the spin axis. Having only one attitude thruster on a spinning spacecraft could be preferred for spacecraft simplicity (lower mass, lower power consumption etc.), or it could be imposed in the context of redundancy/contingency operations. This constraint does yield restrictions on the thruster timings, depending on the ratio of minor to major moments of inertia among other parameters. The Japanese Lunar-A penetrator spacecraft proposal is a good example of such a single-thruster spin-stabilised prolate spacecraft. The attitude dynamics of a spinning rigid body are first investigated analytically, then expanded for the specific case of a prolate and axisymmetric rigid body and finally a cursory exploration of non-rigid body dynamics is made. Next two well-known techniques for manoeuvring a spin-stabilised spacecraft, the Half-cone/Multiple Half-cone and the Rhumb line slew, are compared with two new techniques, the Sector-Arc Slew developed by Astrium Satellites and the Dual-cone developed at Surrey Space Centre. Each technique is introduced and characterised by means of simulation results and illustrations based on the penetrator mission scenario and a brief robustness analysis is performed against errors in moments of inertia and spin rate. Also, the relative benefits of each slew algorithm are discussed in terms of slew accuracy, energy (propellant) efficiency and time efficiency. For example, a sequence of half-cone manoeuvres (a Multi-half-cone manoeuvre) tends to be more energy-efficient than one half-cone for the same final slew angle, but more time-consuming. As another

  1. On-chip micro-coil technique for single electron spin resonance with quantum dot

    NASA Astrophysics Data System (ADS)

    Obata, T.; Pioro-Ladrière, M.; Kubo, T.; Yoshida, K.; Tokura, Y.; Tarucha, S.

    2007-12-01

    We have developed a combined setup consisting of an on-chip micro-coil and a quantum dot for implementing single electron spin resonance, which operates relevantly even at dilution refrigerator temperatures. We have examined the micro-coil performance of the high-frequency response. Capacitive coupling between the coil and the quantum dot causes photon-assisted tunneling, whose signal can overlap greatly with the electron spin resonance signal. We have developed a technique to compensate for the influence of the capacitive coupling, and checked the performance using Coulomb blockade transport.

  2. Altered spin state equilibrium in the T309V mutant of cytochrome P450 2D6: a spectroscopic and computational study

    PubMed Central

    Bonifacio, Alois; Groenhof, André R.; Keizers, Peter H. J.; de Graaf, Chris; Commandeur, Jan N. M.; Vermeulen, Nico P. E.; Ehlers, Andreas W.; Lammertsma, Koop; Gooijer, Cees

    2007-01-01

    Cytochrome P450 2D6 (CYP2D6) is one of the most important cytochromes P450 in humans. Resonance Raman data from the T309V mutant of CYP2D6 show that the substitution of the conserved I-helix threonine situated in the enzyme’s active site perturbs the heme spin equilibrium in favor of the six-coordinated low-spin species. A mechanistic hypothesis is introduced to explain the experimental observations, and its compatibility with the available structural and spectroscopic data is tested using quantum-mechanical density functional theory calculations on active-site models for both the CYP2D6 wild type and the T309V mutant. Electronic supplementary material The online version of this article (doi:10.1007/s00775-007-0210-5) contains supplementary material, which is available to authorized users. PMID:17318599

  3. Electron spin echo envelope modulation studies of the Cu(II)-substituted derivative of isopenicillin N synthase: A structural and spectroscopic model

    SciTech Connect

    Feng Jiang; Peisach, J. ); Lijune Ming; Que, L. Jr. ); Chen, V.J. )

    1991-12-03

    Electron spin echo envelope modulation spectroscopy (ESEEM) was used to study the active site structure of isopenicillin N synthase (IPNS) from Cephalosporium acremonium with Cu(II) as a spectroscopic probe. Fourier transform of the simulated electron spin-echo envelope for the Cu(II)-substituted enzyme, Cu(II)IPNS, revealed two nearly magnetically equivalent, equatorially coordinated His imidazoles. The superhyperfine coupling constant, A{sub iso}, for the remote {sup 14}N of each imidazole was 1.65 MHz. The binding of substrate to the enzyme altered the magnetic coupling so that A{sub iso} is 1.30 MHz for one nitrogen and 2.16 MHz for the other. From a comparison of the ESSEM of Cu(II)IPNS in D{sub 2}O and H{sub 2}O, it is suggested that water is a ligand of Cu(II) and this is displaced upon the addition of substrate.

  4. New technique for single-scan T1 measurements using solid echoes. [for spin-lattice relaxation time

    NASA Technical Reports Server (NTRS)

    Burum, D. P.; Elleman, D. D.; Rhim, W. K.

    1978-01-01

    A simple technique for single-scan T1 measurements in solids is proposed and analyzed for single exponential spin-lattice relaxation. In this technique, the direct spin heating caused by the sampling process is significantly reduced in comparison with conventional techniques by utilizing the 'solid echo' to refocus the magnetization. The applicability of this technique to both the solid and liquid phases is demonstrated.

  5. Study of SnS2 thin film deposited by spin coating technique

    NASA Astrophysics Data System (ADS)

    Chaki, Sunil H.; Joshi, Hardikkumar J.; Tailor, Jiten P.; Deshpande, M. P.

    2017-07-01

    Thin film deposition of SnS2 was done by spin coating technique at ambient temperature. Deposition was done for different spin speed and spin time. The film thickness dependence on spin speed and spin time was studied. The spin speed was varied from 1000 rpm to 2000 rpm and spin time from 2 s to 6 s for constant speed of 1000 rpm. The elemental composition and crystal structure along with the phase of the as-deposited thin film was determined by the energy dispersive analysis of x-ray (EDAX) and x-ray diffraction (XRD) techniques respectively. The as-deposited thin film was found to be near stoichiometric and possess hexagonal crystal structure with determined lattice parameters in good agreement with the reported values. The crystallite size calculated from the XRD data using Scherrer’s formula and Hall-Williamson relation came out to be 9.77 nm and 6.49 nm, respectively. The transmission electron microscopy (TEM) study of spin deposited thin films showed the film to be continuous. Surface study of the as-deposited thin film was done by simple optical microscope and scanning electron microscope (SEM). The study showed that the deposited thin film to be flat and uniform without visible cracks and pores. The optical spectroscopy study of the as-deposited thin film showed that the optical bandgap value decreases with increase in film thickness. The d.c. electrical resistivity variation with temperature for spin coating as-deposited SnS2 film showed that the resistivity decreases with increase in temperature corroborating the semiconducting nature. The resistivity variation plot possesses two slopes. The temperature ranges showing two slopes lay between 300 to 383 K and 384 to 423 K having activation energy values for the two temperature ranges as 0.072 eV and 0.633 eV, respectively. The achieved results are deliberated in details.

  6. [Application of Raman spectroscopic technique to the identification and investigation of Chinese ancient jades and jade artifacts].

    PubMed

    Zhao, Hong-Xia; Gan, Fu-Xi

    2009-11-01

    Laser Raman spectroscopic technique is one of the essential methods in scientific archaeological research, which belongs to the nondestructive analysis. As a very good nondestructive analysis approach, it has not been widely applied in the research of the Chinese ancient jade artifacts. First of all in the present paper the fundamentals of laser Raman spectroscopic technique and the new research progress in this field were reviewed. Secondly, the Raman spectra of five familiar jades including nephrite (mainly composed of tremolite), Xiuyan Jade (mainly composed of serpentine), Dushan Jade (mainly composed of anorthite and Zoisite), turquoise and lapis lazuli were summarized respectively. As for an example, the Raman spectra of the four Chinese ancient jade artifacts excavated from Liangzhu Site of Zhejiang Province and Yinxu Site of Anyang in Henan Province were compared with that of the nephrite sample in Hetian of Xinjiang Province. It was shown that the Raman spectroscopic technique is a good nondestructive approach to the identification and investigation of the structures and mineral composition of Chinese ancient jade artifacts. Finally, the limitations and the foreground of this technique were discussed.

  7. Frequency-scanned ultrafast spectroscopic techniques applied to infrared four-wave mixing spectroscopy

    NASA Astrophysics Data System (ADS)

    Meyer, Kent Albert

    Frequency-scanned techniques of ultrafast spectroscopy were applied to infrared four-wave mixing (IRFWM) in order to determine their effectiveness in the detection and quantification of vibrationally coupled modes. Frequency-scanned ultrafast techniques are a mixed version of frequency and time domain approaches with some advantages of each domain. The frequency domain advantages include the ability to select individual components from a mixture; time domain advantages include the ability to temporally discriminate many non-linear pathways that can congest spectra and interpretation. These advantages have been experimentally verified with doubly vibrationally enhanced (DOVE) and triply vibrationally enhanced (TRIVE) FWM using dilute carbon disulfide as a model system. DOVE and TRIVE are multi-dimensional vibrational coupling techniques analogous to multi-dimensional NMR spin coupling techniques. They differ from NMR in that DOVE and TRIVE spectroscopy occur on the ultrafast (<1 ps) timescale and can provide new chemical dynamics information. Quantification of DOVE signal has been performed computationally of dilute carbon disulfide and agrees with values extracted from linear infrared spectra. Additional parameters from computational models show population dephasing contributions of dilute carbon disulfide's major combination band and strongly absorbing fundamental to be values not far from expected ones. An advantage of TRIVE over the standard IR-IR pump-probe methods is in the possible reduction of the total number of interfering pathways. Pathways not typically explored in the pump-probe paths may be useful in their line narrowing of correlated vibrational modes. The issue of broadening of spectral lines in mixed domain spectra due to the breadth of the electric fields has been addressed with the concept of gated line narrowing. Shaped input pulses can narrow homogeneously broadened lines when gated at a far time. In TRIVE, gating can take place in the form of

  8. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials

    DOE PAGES

    Wu, Peiwen; Yu, Yang; McGhee, Claire E.; ...

    2014-09-10

    In this paper, we summarize recent progress in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insightsmore » gained from these studies are described and future directions of this field are also discussed.« less

  9. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials

    SciTech Connect

    Wu, Peiwen; Yu, Yang; McGhee, Claire E.; Tan, Li Huey; Lu, Yi

    2014-09-10

    In this paper, we summarize recent progress in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insights gained from these studies are described and future directions of this field are also discussed.

  10. Advances in Understanding the Molecular Structures and Functionalities of Biodegradable Zein-Based Materials Using Spectroscopic Techniques: A Review.

    PubMed

    Turasan, Hazal; Kokini, Jozef L

    2017-02-13

    Zein's amphiphilic properties, film forming capability, and biodegradability make it a highly demanded polymer for fabrication of packaging materials, production of drug carrier nanoparticles, scaffolds in tissue engineering, and formation of biodegradable platforms for biosensors including microfluidic devices. Zein properties can be improved by chemical modifications, which are often analyzed with spectroscopic techniques. However, there is not a consensus on the structure of zein. For this reason, in this Review the aim is to compile the recent studies conducted on zein-based products and compare them under five main spectroscopic techniques: Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, circular dichroism (CD), X-ray diffraction (XRD) and atomic force microscopy (AFM). This Review serves as a library of recent zein studies and helps readers to have a better perception of contradictions in the literature to take their studies one step further.

  11. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials

    PubMed Central

    Wu, Peiwen; Yu, Yang; McGhee, Claire E.; Tan, Li Huey

    2014-01-01

    In this review, we summarize recent progresses in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insights gained from these studies are described and future directions of this field are also discussed. PMID:25205057

  12. Applications of synchrotron-based spectroscopic techniques in studying nucleic acids and nucleic acid-functionalized nanomaterials.

    PubMed

    Wu, Peiwen; Yu, Yang; McGhee, Claire E; Tan, Li Huey; Lu, Yi

    2014-12-10

    In this review, we summarize recent progress in the application of synchrotron-based spectroscopic techniques for nucleic acid research that takes advantage of high-flux and high-brilliance electromagnetic radiation from synchrotron sources. The first section of the review focuses on the characterization of the structure and folding processes of nucleic acids using different types of synchrotron-based spectroscopies, such as X-ray absorption spectroscopy, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, synchrotron radiation circular dichroism, X-ray footprinting and small-angle X-ray scattering. In the second section, the characterization of nucleic acid-based nanostructures, nucleic acid-functionalized nanomaterials and nucleic acid-lipid interactions using these spectroscopic techniques is summarized. Insights gained from these studies are described and future directions of this field are also discussed.

  13. Electric field measurements of the LH wave and ICRF near-field utilizing non-perturbative spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Martin, E. H.; Caughman, J. B. O.; Klepper, C. C.; Goniche, M.; Isler, R. C.; Hillairet, J.; Bottereau, C.

    2015-12-01

    The physics of wave heating and current drive processes in the bulk hot plasma are generally well identified. However, details of the wave-plasma interaction in the cold plasma edge are still not fully understood. In this paper a spectroscopic technique allowing for measurements of the electric field driving wave-plasma interactions in the edge region for LH current drive and ICRH systems will be discussed. Experimental results obtained in Tore Supra near the LH C3 antenna and in the magnetized capacitively coupled RF sheath from an experiment designed to mimic the ICRF near-field are presented. In conclusion, future plans to implement a laser-based spectroscopic technique to acquire the high resolution measurements needed for model validation is discussed.

  14. Determination of lipid content of oleaginous microalgal biomass by NMR spectroscopic and GC-MS techniques.

    PubMed

    Sarpal, Amarijt S; Teixeira, Claudia M L L; Silva, Paulo R M; Lima, Gustavo M; Silva, Samantha R; Monteiro, Thays V; Cunha, Valnei S; Daroda, Romeu J

    2015-05-01

    Direct methods based on (1)H NMR spectroscopic techniques have been developed for the determination of neutral lipids (triglycerides and free fatty acids) and polar lipids (glyceroglycolipids/phospholipids) in the solvent extracts of oleaginous microalgal biomasses cultivated on a laboratory scale with two species in different media. The chemical shift assignments observed in the (1)H and (13)C NMR spectra corresponding to unsaturated (C18:N, N = 1-3, C20:3, C20:5, C22:6, epoxy) and saturated (C14-C18) fatty acid ester components in a complex matrix involving overlapped resonances have been unambiguously confirmed by the application of 2D NMR spectroscopy (total correlation spectroscopy and heteronuclear single quantum coherence-total correlation spectroscopy). The study of the effect of a polar lipid matrix on the determination of neutral lipids by an internal reference blending process by a systematic designed experimental protocol has provided absolute quantification. The fatty acid composition of algal extracts was found to be similar to that of vegetable oils containing saturated (C16-C18:0) and unsaturated (C18:N, N = 1-3, C20:N, N = 3-4, C22:6) fatty acids as confirmed by NMR spectroscopy and gas chromatography-mass spectrometry analyses. The NMR methods developed offer great potential for rapid screening of algal strains for generation of algal biomass with the desired lipid content, quality, and potential for biodiesel and value-added polyunsaturated fatty acids in view of the cost economics of the overall cost of generation of the biomass.

  15. Electron spin-echo techniques for the study of protein motion

    NASA Astrophysics Data System (ADS)

    Kar, Leela; Johnson, Michael E.; Bowman, Michael K.

    Electron spin-echo (ESE) spectroscopy has been used to make the first direct measurements of spin-spin relaxation times of a spin-labeled protein at physiological temperatures. Results from experiments using maleimide-labeled deoxygenated hemoglobin (dHb) from individuals homozygous for sickle cell anemia (dHbS) have been compared with those from control experiments using dHb from normal adults (dHbA). Hb "immobilized" by ammonium sulfate precipitation and by siloxane polymer entrapment have been studied for a suitable "rigid" reference. Two-dimensional ESE (2D-ESE) experiments have been performed using all of these systems. The 2D contour plots show that 2D-ESE is sensitive to the slow motion of dHbS polymers and can differentiate it from both that of immobilized Hb and of HbA molecules in solution at the same temperature and concentration. More importantly, the 2D-ESE technique enables one to select for slower motion and thereby extract the dHbS polymer signal from the total signal generated by the heterogeneous system containing dHbS molecules in solution as well as in the polymer. Computer simulations using current slow motional theories show that detailed motional and structural information may be obtained by such studies. The considerable potential of 2D-ESE spectroscopy in the study of macromolecular motion is illustrated by comparing 2D-ESE with the nonlinear technique of saturation transfer electron paramagnetic resonance.

  16. Pseudo-continuous arterial spin labeling technique for measuring CBF dynamics with high temporal resolution.

    PubMed

    Silva, A C; Kim, S G

    1999-09-01

    Cerebral blood flow (CBF) can be measured noninvasively with nuclear magnetic resonance (NMR) by using arterial water as an endogenous perfusion tracer. However, the arterial spin labeling (ASL) techniques suffer from poor temporal resolution due to the need to wait for the exchange of labeled arterial spins with tissue spins to produce contrast. In this work, a new ASL technique is introduced, which allows the measurement of CBF dynamics with high temporal and spatial resolution. This novel method was used in rats to determine the dynamics of CBF changes elicited by somatosensory stimulation with a temporal resolution of 108 ms. The onset time of the CBF response was 0.6 +/- 0.4 sec (mean +/- SD) after onset of stimulation (n = 10). The peak response was observed 4.4 +/- 3.7 sec (mean +/- SD) after stimulation began. These results are in excellent agreement with previous data obtained with invasive techniques, such as laser-Doppler flowmetry and hydrogen clearance, and suggest the appropriateness of this novel technique to probe CBF dynamics in functional and pathological studies with high temporal and spatial resolution. Magn Reson Med 42:425-429, 1999.

  17. Microwave band on-chip coil technique for single electron spin resonance in a quantum dot

    NASA Astrophysics Data System (ADS)

    Obata, Toshiaki; Pioro-Ladrière, Michel; Kubo, Toshihiro; Yoshida, Katsuharu; Tokura, Yasuhiro; Tarucha, Seigo

    2007-10-01

    Microwave band on-chip microcoils are developed for the application to single electron spin resonance measurement with a single quantum dot. Basic properties such as characteristic impedance and electromagnetic field distribution are examined for various coil designs by means of experiment and simulation. The combined setup operates relevantly in the experiment at dilution temperature. The frequency responses of the return loss and Coulomb blockade current are examined. Capacitive coupling between a coil and a quantum dot causes photon assisted tunneling, whose signal can greatly overlap the electron spin resonance signal. To suppress the photon assisted tunneling effect, a technique for compensating for the microwave electric field is developed. Good performance of this technique is confirmed from measurement of Coulomb blockade oscillations.

  18. Explicit demonstration of spinor character for a spin-1/2 nucleus via NMR interferometry

    NASA Technical Reports Server (NTRS)

    Stoll, M. E.; Vaughan, R. W.; Vega, A. J.

    1977-01-01

    The results of a nuclear-magnetic-resonance experiment are presented which directly demonstrate the spinor character of a spin-1/2 nucleus, C-13. The interferometric spectroscopic technique used and its potential applications are discussed.

  19. Radio-controlled model design and testing techniques for stall/spin evaluation of general-aviation aircraft

    NASA Technical Reports Server (NTRS)

    Burk, S. M., Jr.; Wilson, C. F., Jr.

    1975-01-01

    A relatively inexpensive radio-controlled model stall/spin test technique was developed. Operational experiences using the technique are presented. A discussion of model construction techniques, spin-recovery parachute system, data recording system, and movie camera tracking system is included. Also discussed are a method of measuring moments of inertia, scaling of engine thrust, cost and time required to conduct a program, and examples of the results obtained from the flight tests.

  20. Accurate spectroscopic calculations of the 14 Λ-S and 30 Ω states of BF+ cation including the spin-orbit coupling effect

    NASA Astrophysics Data System (ADS)

    Zhu, Wenjie; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2017-01-01

    This paper studied the potential energy curves of 30 Ω states yielded from the 14 Λ-S states (X2Σ+, 12Π, 22Π, 32Π, 12Σ-, 22Σ+, 32Σ+, 12Δ, 14Σ-, 14Σ+, 24Σ+, 14Π, 24Π, and 14Δ) of the BF+ cation. The potential energy curves were calculated for internuclear separations from approximately 0.08 to 1.1 nm using the CASSCF method, which was followed by the icMRCI approach with the aug-cc-pV6Z basis set. Of these 14 Λ-S states, the 24Σ+ and 24Π states were repulsive. The 22Π and 32Π states had double wells. The avoided crossings were found between the 12Π and the 22Π state, and between the 32Π and the 42Π state. The 12Π, 22Π, 32Π, and 14Π states were inverted with the spin-orbit coupling effect taken into account. The 14Π state and the second wells of 22Π and 32Π states were weakly bound. Each of the 12Π, 22Π, and 32Π states had one barrier. The potential energy curves of all the Λ-S and Ω states were extrapolated to the complete basis set limit. Core-valence correlation and scalar relativistic corrections were included at the level of an aug-cc-pV5Z basis set. The spin-orbit coupling effect was included by the state interaction approach with the Breit-Pauli Hamiltonian and the all-electron cc-pCV5Z set. The spectroscopic parameters were determined and compared with available experimental and other theoretical ones. The spin-orbit coupling effect on the spectroscopic parameters was evaluated in detail. Comparison with available experimental data show that the methodology used in this paper is highly accurate for this system.

  1. New spectroscopic data, spin-orbit functions, and global analysis of data on the A 1Sigmau+ and b 3Piu states of Na2.

    PubMed

    Qi, P; Bai, J; Ahmed, E; Lyyra, A M; Kotochigova, S; Ross, A J; Effantin, C; Zalicki, P; Vigué, J; Chawla, G; Field, R W; Whang, T-J; Stwalley, W C; Knöckel, H; Tiemann, E; Shang, J; Li, L; Bergeman, T

    2007-07-28

    The lowest electronically excited states of Na2 are of interest as intermediaries in the excitation of higher states and in the development of methods for producing cold molecules. We have compiled previously obtained spectroscopic data on the A 1Sigmau+ and b 3Piu states of Na2 from about 20 sources, both published and unpublished, together with new sub-Doppler linewidth measurements of about 15,000 A<--X transitions using polarization spectroscopy. We also present new ab initio results for the diagonal and off-diagonal spin-orbit functions. The discrete variable representation is used in conjunction with Hund's case a potentials plus spin-orbit effects to model data extending from v=0 to very close to the 3 2S+3 2P12 limit. Empirical estimates of the spin-orbit functions agree well with the ab initio functions for the accessible values of R. The potential function for the A state includes an exchange potential for S+P atoms, with a fitted coefficient somewhat larger than the predicted value. Observed and calculated term values are presented in an auxiliary (EPAPS) file as a database for future studies on Na2.

  2. Observation of the origin of d0 magnetism in ZnO nanostructures using X-ray-based microscopic and spectroscopic techniques.

    PubMed

    Singh, Shashi B; Wang, Yu-Fu; Shao, Yu-Cheng; Lai, Hsuan-Yu; Hsieh, Shang-Hsien; Limaye, Mukta V; Chuang, Chen-Hao; Hsueh, Hung-Chung; Wang, Hsaiotsu; Chiou, Jau-Wern; Tsai, Hung-Ming; Pao, Chih-Wen; Chen, Chia-Hao; Lin, Hong-Ji; Lee, Jyh-Fu; Wu, Chun-Te; Wu, Jih-Jen; Pong, Way-Faung; Ohigashi, Takuji; Kosugi, Nobuhiro; Wang, Jian; Zhou, Jigang; Regier, Tom; Sham, Tsun-Kong

    2014-08-07

    Efforts have been made to elucidate the origin of d(0) magnetism in ZnO nanocactuses (NCs) and nanowires (NWs) using X-ray-based microscopic and spectroscopic techniques. The photoluminescence and O K-edge and Zn L3,2-edge X-ray-excited optical luminescence spectra showed that ZnO NCs contain more defects than NWs do and that in ZnO NCs, more defects are present at the O sites than at the Zn sites. Specifically, the results of O K-edge scanning transmission X-ray microscopy (STXM) and the corresponding X-ray-absorption near-edge structure (XANES) spectroscopy demonstrated that the impurity (non-stoichiometric) region in ZnO NCs contains a greater defect population than the thick region. The intensity of O K-edge STXM-XANES in the impurity region is more predominant in ZnO NCs than in NWs. The increase in the unoccupied (occupied) density of states at/above (at/below) the conduction-band minimum (valence-band maximum) or the Fermi level is related to the population of defects at the O sites, as revealed by comparing the ZnO NCs to the NWs. The results of O K-edge and Zn L3,2-edge X-ray magnetic circular dichroism demonstrated that the origin of magnetization is attributable to the O 2p orbitals rather than the Zn d orbitals. Further, the local density approximation (LDA) + U verified that vacancies in the form of dangling or unpaired 2p states (due to Zn vacancies) induced a significant local spin moment in the nearest-neighboring O atoms to the defect center, which was determined from the uneven local spin density by analyzing the partial density of states of O 2p in ZnO.

  3. Fatty infiltration of the liver: demonstration by proton spectroscopic imaging: preliminary observations

    SciTech Connect

    Lee, J.K.T.; Dixon, W.T.; Ling, D.; Levitt, R.G.; Murphy, W.A. Jr.

    1984-10-01

    Two normal volunteers and three patients with CT evidence of fatty infiltration of the liver were studied to determine whether magnetic resonance imaging using a pulse sequence designed to differentiate fat and water could be used to detect fatty infiltration of the liver in human being. The magnetic resonance technique used a modified spin echo technique (simple proton spectroscopic imaging). Quantitative data showed that fatty liver can be separated from normal liver using the spin echo technique, and that the opposed image of the proton spectroscopic technique is more sensitive to small changes in hepatic fatty content than in-phase images with any echo time.

  4. Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. Master's thesis

    SciTech Connect

    Shaffer, B.L.

    1990-12-01

    Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. The M0006 semiconductor samples were placed into a 28.5 degree inclination, 480 km altitude, near-circular orbit aboard the Long Duration Exposure Facility satellite and exposed to direct space environment for a period of 11 months, and were shielded by 0.313 inches of aluminum for another 58 months. The samples were examined for changes using cathodoluminescence and photoluminescence in various wavelength regions from 0.5 to 1.8 micrometers. Samples were cooled to approximately 10 degrees Kelvin in a vacuum of 10-8. (JS)

  5. Development and Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control

    SciTech Connect

    Ken Czerwinski; Phil Weck; Frederic Poineau

    2010-12-29

    Ultraviolet-Visible Spectroscopy (UV-Visible) and Time Resolved Laser Fluorescence Spectroscopy (TRLFS) optical techniques can permit on-line, real-time analysis of the actinide elements in a solvent extraction process. UV-Visible and TRLFS techniques have been used for measuring the speciation and concentration of the actinides under laboratory conditions. These methods are easily adaptable to multiple sampling geometries, such as dip probes, fiber-optic sample cells, and flow-through cell geometries. To fully exploit these techniques for GNEP applications, the fundamental speciation of the target actinides and the resulting influence on 3 spectroscopic properties must be determined. Through this effort detection limits, process conditions, and speciation of key actinide components can be establish and utilized in a range of areas of interest to GNEP, especially in areas related to materials accountability and process control.

  6. Imaging of Heterogeneous Materials with a Turbo Spin Echo Single-Point Imaging Technique

    NASA Astrophysics Data System (ADS)

    Beyea, Steven D.; Balcom, Bruce J.; Mastikhin, Igor V.; Bremner, Theodore W.; Armstrong, Robin L.; Grattan-Bellew, Patrick E.

    2000-06-01

    A magnetic resonance imaging method is presented for imaging of heterogeneous broad linewidth materials. This method allows for distortionless relaxation weighted imaging by obtaining multiple phase encoded k-space data points with each RF excitation pulse train. The use of this method, turbo spin echo single-point imaging-(turboSPI), leads to decreased imaging times compared to traditional constant-time imaging techniques, as well as the ability to introduce spin-spin relaxation contrast through the use of longer effective echo times. Imaging times in turboSPI are further decreased through the use of low flip angle steady-state excitation. Two-dimensional images of paramagnetic doped agarose phantoms were obtained, demonstrating the contrast and resolution characteristics of the sequence, and a method for both amplitude and phase deconvolution was demonstrated for use in high-resolution turboSPI imaging. Three-dimensional images of a partially water-saturated porous volcanic aggregate (T2L ≈ 200 ms, Δν1/2 ≈ 2500 Hz) contained in a hardened white Portland cement matrix (T2L ≈ 0.5 ms, Δν1/2 ≈ 2500 Hz) and a water-saturated quartz sand (T2 ≈ 300 ms, T2* ≈ 800 μs) are shown.

  7. Fabricating tubular scaffolds with a radial pore size gradient by a spinning technique.

    PubMed

    Harley, Brendan A; Hastings, Abel Z; Yannas, Ioannis V; Sannino, Alessandro

    2006-02-01

    A novel fabrication process has been developed to produce collagen-based, porous tubular scaffolds to facilitate the study of myofibroblast migration during peripheral nerve regeneration; however, this fabrication technique offers broader appeal for the production of a variety of tubular structures without the use of a complicated mold system. A collagen-glycosaminoglycan (CG) suspension in acetic acid was spun in a cylindrical copper mold about its longitudinal axis at variable angular velocities and for different times, resulting in variable relative sedimentation of the CG content towards the mold outer edge; after the specified spinning time, the spinning mold was placed into a bath of liquid nitrogen where the CG suspension was rapidly frozen. Due to the rapid solidification, the CG content remained sedimented while an interconnected network of ice crystals formed throughout. Sublimation of the frozen mass removed the solvent (acetic acid) content, producing a porous, tubular structure defined by sedimentation and ice crystal nucleation processes. A porous, tubular scaffold with a sharply defined inner tube wall can be produced; further, increasing the spinning time and/or spinning velocity increases the sedimentation effect leading to the production of a hollow tube with a larger inner diameter. The tube walls display a radially aligned pore structure, even in cases where sedimentation was not sufficient to produce a hollow tube. A gradient of porosity along the tube radius was also observed in cases of extreme sedimentation: the pore structure of the external portion of the tube wall had a larger solid volume fraction and a smaller mean pore size compared to the internal portion of the tube. This tubular structure may allow preferential cell migration from the inner tube lumen towards the outer tube edge while blocking cell entrance into the tube through its outer surface due to increased scaffold relative density and decreased pore size.

  8. Laser-spectroscopic measurement techniques for hypersonic, turbulent wind tunnel flows

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert L.; Fletcher, Douglas G.

    1992-01-01

    A review is given of the nature, present status, and capabilities of two laser spectroscopic methods for the simultaneous measurement of temperature, density, and their fluctuations owing to turbulence in high speed wind tunnel flows. One method is based on the two frequency excitation of nitric oxide seeded into a nitrogen flow, using tunable dye lasers. The second, more recent method relies on the excitation of oxygen in air flows using a tunable, ArF excimer laser. Signal are obtained from both the laser induced fluorescence and from Raman scattering of the same laser pulse. Measurements are demonstrated in the turbulent boundary layer of a Mach-2 channel flow.

  9. Ultrafast IR spectroscopic study of coherent phonons and dynamic spin-lattice coupling in multiferroic LuMnO3

    NASA Astrophysics Data System (ADS)

    Jang, Kyeong-Jin; Lim, Jongseok; Ahn, Jaewook; Kim, Ji-Hee; Yee, Ki-Ju; Ahn, Jai Seok; Cheong, Sang-Wook

    2010-02-01

    The concurrent existence of ferroelectricity and magnetism within a single crystalline system characterizes the multiferroic materials discovered in recent years. To understand and develop the multiferroic phenomenon, we need to investigate the unusual coupling between spin and lattice degrees of freedom. Spins in multiferroics are expected to be elastically coupled to phonons. Therefore, the time-dependent study can be a crucial factor in understanding the coupled dynamics. Here, we report the observations of strong dynamic spin-lattice coupling in multiferroic LuMnO3. A coherent optical phonon of 3.6 THz and its temperature dependence is measured for the first time from our femtosecond IR pump and probe spectroscopy. Also, we observed a coherent acoustic phonon of 47 GHz similar to a previous report (Lim et al 2003 Appl. Phys. Lett. 83 4800). Temperature-dependent measurements show that both optical and acoustic phonons become significantly underdamped as temperature decreases to TN, and they disappear below TN. These observations reveal that phonons are coupled to spins by magneto-elastic coupling, and the disappearance of phonon modes at TN is consistent with the isostructural coupling scheme suggested by Lee et al (2008 Nature 451 805).

  10. Accurate calculations on 9 Λ-S and 28 Ω states of NSe radical in the gas phase: Potential energy curves, spectroscopic parameters and spin-orbit couplings

    NASA Astrophysics Data System (ADS)

    Shi, Deheng; Li, Peiling; Sun, Jinfeng; Zhu, Zunlue

    2014-01-01

    The potential energy curves (PECs) of 28 Ω states generated from 9 Λ-S states (X2Π, 14Π, 16Π, 12Σ+, 14Σ+, 16Σ+, 14Σ-, 24Π and 14Δ) are studied for the first time using an ab initio quantum chemical method. All the 9 Λ-S states correlate to the first two dissociation limits, N(4Su) + Se(3Pg) and N(4Su) + Se(3Dg), of NSe radical. Of these Λ-S states, the 16Σ+, 14Σ+, 16Π, 24Π and 14Δ are found to be rather weakly bound states. The 12Σ+ is found to be unstable and has double wells. And the 16Σ+, 14Σ+, 14Π and 16Π are found to be the inverted ones with the SO coupling included. The PEC calculations are made by the complete active space self-consistent field method, which is followed by the internally contracted multireference configuration interaction approach with the Davidson modification. The spin-orbit coupling is accounted for by the state interaction approach with the Breit-Pauli Hamiltonian. The convergence of the present calculations is discussed with respect to the basis set and the level of theory. Core-valence correlation corrections are included with a cc-pCVTZ basis set. Scalar relativistic corrections are calculated by the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. All the PECs are extrapolated to the complete basis set limit. The variation with internuclear separation of spin-orbit coupling constants is discussed in brief for some Λ-S states with one shallow well on each PEC. The spectroscopic parameters of 9 Λ-S and 28 Ω states are determined by fitting the first ten vibrational levels whenever available, which are calculated by solving the rovibrational Schrödinger equation with Numerov's method. The splitting energy in the X2Π Λ-S state is determined to be about 864.92 cm-1, which agrees favorably with the measurements of 891.80 cm-1. Moreover, other spectroscopic parameters of Λ-S and Ω states involved here are also in fair agreement with available measurements. It

  11. a Technique to Calibrate Neutron-Proton Elastic Scattering Spin Observables Near 183 Mev

    NASA Astrophysics Data System (ADS)

    Bowyer, Theodore William

    Free neutron-proton scattering is one of the most fundamental reactions we can study in the field of nuclear physics, yet the n-p scattering data base is quite sparse. The data that does exist is often plagued by systematic uncertainties associated with the determination of beam and/or target polarizations. In contrast, there is an abundance of high quality, high statistics p-p elastic scattering data. We report on a technique which we have developed which exploits the high quality of the p-p data to calibrate n-p elastic scattering spin observables by simultaneous measurement of vec n-vec p and p-vec p elastic scattering by bombarding a polarized proton target with a mixed beam of polarized neutrons and protons. This technique has allowed us to calibrate the n-p elastic spin observables at 183 MeV: the beam and target analyzing powers A _{n}(theta_{p}),A _{p}(theta p), and the spin correlation coefficient, C_{NN}( theta_{p}). The mixed secondary beam was produced by bombarding a liquid deuterium target with a 200 MeV beam of polarized protons. The experiment was preformed in the Polarized Neutron Facility at the Indiana University Cyclotron Facility utilizing a left-right symmetric detection system, sensitive to both scattered protons and neutrons, and spanned the laboratory angular range of 24^circ to 62^circ. We identified free scattering events through a number of kinematic correlations. We compare our results to various phase shift calculations and potential models and examine the sensitivity of magnitude of various phase shifts results to the inclusion of our data into the n-p data base.

  12. Artificial tektites: an experimental technique for capturing the shapes of spinning drops

    NASA Astrophysics Data System (ADS)

    Baldwin, Kyle A.; Butler, Samuel L.; Hill, Richard J. A.

    2015-01-01

    Determining the shapes of a rotating liquid droplet bound by surface tension is an archetypal problem in the study of the equilibrium shapes of a spinning and charged droplet, a problem that unites models of the stability of the atomic nucleus with the shapes of astronomical-scale, gravitationally-bound masses. The shapes of highly deformed droplets and their stability must be calculated numerically. Although the accuracy of such models has increased with the use of progressively more sophisticated computational techniques and increases in computing power, direct experimental verification is still lacking. Here we present an experimental technique for making wax models of these shapes using diamagnetic levitation. The wax models resemble splash-form tektites, glassy stones formed from molten rock ejected from asteroid impacts. Many tektites have elongated or `dumb-bell' shapes due to their rotation mid-flight before solidification, just as we observe here. Measurements of the dimensions of our wax `artificial tektites' show good agreement with equilibrium shapes calculated by our numerical model, and with previous models. These wax models provide the first direct experimental validation for numerical models of the equilibrium shapes of spinning droplets, of importance to fundamental physics and also to studies of tektite formation.

  13. Application of a system modification technique to dynamic tuning of a spinning rotor blade

    NASA Technical Reports Server (NTRS)

    Spain, C. V.

    1987-01-01

    An important consideration in the development of modern helicopters is the vibratory response of the main rotor blade. One way to minimize vibration levels is to ensure that natural frequencies of the spinning main rotor blade are well removed from integer multiples of the rotor speed. A technique for dynamically tuning a finite-element model of a rotor blade to accomplish that end is demonstrated. A brief overview is given of the general purpose finite element system known as Engineering Analysis Language (EAL) which was used in this work. A description of the EAL System Modification (SM) processor is then given along with an explanation of special algorithms developed to be used in conjunction with SM. Finally, this technique is demonstrated by dynamically tuning a model of an advanced composite rotor blade.

  14. New Spectroscopic Technique Based on Coaddition of Surface Brightness Fluctuations: NGC 4449 and its Stellar Tidal Stream

    NASA Astrophysics Data System (ADS)

    Toloba, Elisa; Guhathakurta, Puragra; Romanowsky, Aaron J.; Brodie, Jean P.; Martínez-Delgado, David; Arnold, Jacob A.; Ramachandran, Neel; Theakanath, Kuriakose

    2016-06-01

    We present a new spectroscopic technique based in part on targeting the upward fluctuations of the surface brightness for studying the internal stellar kinematics and metallicities of galaxies of low surface brightness effects both to galaxies and streams beyond the Local Group. The distance to these systems makes them unsuitable for targeting individual red giant branch (RGB) stars (tip of RGB at I≳ 24 mag) and their surface brightness is too low ({μ }r≳ 25 mag arcsec-2) for integrated light spectroscopic measurements. This technique overcomes these two problems by targeting individual objects that are brighter than the tip of the RGB. We apply this technique to the star-forming dwarf galaxy NGC 4449 and its stellar stream. We use Keck/DEIMOS data to measure the line-of-sight radial velocity out to ˜7 kpc in the east side of the galaxy and ˜8 kpc along the stream. We find that the two systems are likely gravitationally bound to each other and have heliocentric radial velocities of 227.3 ± 10.7 km s-1 and 225.8 ± 16.0 km s-1, respectively. Neither the stream nor the near half of the galaxy shows a significant velocity gradient. We estimate the stellar metallicity of the stream based on the equivalent width of its calcium triplet lines and find [Fe/H] =\\quad -1.37+/- 0.41, which is consistent with the metallicity-luminosity relation for dwarf galaxies in the Local Group. Whether the stream's progenitor was moderately or severely stripped cannot be constrained with this uncertainty in metallicity. We demonstrate that this new technique can be used to measure the kinematics and (possibly) the metallicity of the numerous faint satellites and stellar streams in the halos of nearby (˜4 Mpc) galaxies.

  15. Spin injection and detection in lanthanum- and niobium-doped SrTiO3 using the Hanle technique.

    PubMed

    Han, Wei; Jiang, Xin; Kajdos, Adam; Yang, See-Hun; Stemmer, Susanne; Parkin, Stuart S P

    2013-01-01

    There has been much interest in the injection and detection of spin-polarized carriers in semiconductors for the purposes of developing novel spintronic devices. Here we report the electrical injection and detection of spin-polarized carriers into Nb-doped strontium titanate single crystals and La-doped strontium titanate epitaxial thin films using MgO tunnel barriers and the three-terminal Hanle technique. Spin lifetimes of up to ~100 ps are measured at room temperature and vary little as the temperature is decreased to low temperatures. However, the mobility of the strontium titanate has a strong temperature dependence. This behaviour and the carrier doping dependence of the spin lifetime suggest that the spin lifetime is limited by spin-dependent scattering at the MgO/strontium titanate interfaces, perhaps related to the formation of doping induced Ti(3+). Our results reveal a severe limitation of the three-terminal Hanle technique for measuring spin lifetimes within the interior of the subject material.

  16. Binding studies of lophirone B with bovine serum albumin (BSA): Combination of spectroscopic and molecular docking techniques

    NASA Astrophysics Data System (ADS)

    Chaves, Otávio Augusto; da Silva, Veridiana A.; Sant'Anna, Carlos Maurício R.; Ferreira, Aurélio B. B.; Ribeiro, Tereza Auxiliadora N.; de Carvalho, Mário G.; Cesarin-Sobrinho, Dari; Netto-Ferreira, José Carlos

    2017-01-01

    The interaction between the transport protein bovine serum albumin (BSA) and the natural product lophirone B, was investigated by spectroscopic techniques combined with a computational method (molecular docking). From the KSV and kq values it was concluded that lophirone B quenches the fluorescence of BSA by dynamic and static mechanisms. The Ka values, of the order of 104 M-1, and the number of binding sites (n ≈ 1), indicate that the binding is moderate and there is just one main binding site in BSA for lophirone B. The negative ΔG° values are in accordance with the spontaneity of the process and the positive ΔH° and ΔS° values indicate that the binding is entropically driven; the main binding forces for the association BSA:lophirone B are probably lipophilic interactions. Circular dichroism (CD) studies show there is not a significant perturbation on the secondary structure of the albumin upon the binding process. In order to better understand the spectroscopic results, a computational method was applied: molecular docking suggests Trp-213 site, as the main binding site for the ligand. Lophirone B seems to be exposed to the aqueous media as well as accommodated inside the protein cavity, resulting in a moderate affinity for the albumin. The Arg-198, His-287, Lys-294 and Lys-439 residues are interacting via hydrogen bonding with lophirone B, whereas the interaction with Trp-213 residue occurs through a lipophilic interaction.

  17. CB7 as a drug vehicle and controlled release of drug through non ionic surfactant: Spectroscopic technique.

    PubMed

    Singharoy, Dipti; Mati, Soumya Sundar; Ghosh, Swadesh; Bhattacharya, Subhash Chandra

    2017-09-06

    A study of the comparative drug carrier properties of cucurbituril[7] (CB7) and β-cyclodextrin (β-CD) with a naphthalimide derivative, [2-(2-aminoethyl)-1H-benzo[deisoquinoline-1,3(2H)-dione] (NAP) and its release in aqueous solution using micellar environment, is the key research interest of this work. The profound changes in the different spectroscopic behavior have been attributed to the formation of a 1:1 inclusion complex for NAP:CB7 system. Several experimental outcomes clearly interpreted that CB7 has better drug carrier properties for NAP compared to β-CD. It has been also focused on the systematic release of NAP molecule from CB7 by using different ionic and non ionic surfactants. Before releasing the drug molecules from CB7 the interaction between NAP and the three different types of surfactants has also been investigated separately. The selectivity of drug carrier and releaser has been monitored, using different spectroscopic techniques like absorbance, fluorescence, fluorescence decay life time and (1)H NMR spectroscopy. Besides, a theoretical approach has been followed for a proper geometrical optimized structure of NAP molecule and molecular arrangement of NAP:CB7 inclusion complex. From Density Functional Theory (DFT) it has been seen that NAP molecule is oriented as a t-bone like structure in its optimized form. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Technique to determine location of radio sources from measurements taken on spinning spacecraft

    NASA Technical Reports Server (NTRS)

    Fainberg, J.

    1979-01-01

    The procedure developed to extract average source direction and average source size from spin-modulated radio astronomy data measured on the IMP-6 spacecraft is described. Because all measurements are used, rather than just finding maxima or minima in the data, the method is very sensitive, even in the presence of large amounts of noise. The technique is applicable to all experiments with directivity characteristics. It is suitable for onboard processing on satellites to reduce the data flow to Earth. The application to spin-modulated nonpolarized radio astronomy data is made and includes the effects of noise, background, and second source interference. The analysis was tested with computer simulated data and the results agree with analytic predictions. Applications of this method with IMP-6 radio data have led to: (1) determination of source positions of traveling solar radio bursts at large distances from the Sun; (2) mapping of magnetospheric radio emissions by radio triangulation; and (3) detection of low frequency radio emissions from Jupiter and Saturn.

  19. Spectroscopic and Theoretical Study of Spin-Dependent Electron Transfer in an Iron(III) Superoxo Complex.

    PubMed

    Stout, Heather D; Kleespies, Scott T; Chiang, Chien-Wei; Lee, Way-Zen; Que, Lawrence; Münck, Eckard; Bominaar, Emile L

    2016-06-06

    It was shown previously (J. Am. Chem. Soc. 2014, 136, 10846) that bubbling of O2 into a solution of Fe(II)(BDPP) (H2BDPP = 2,6-bis[[(S)-2-(diphenylhydroxymethyl)-1-pyrrolidinyl]methyl]pyridine) in tetrahydrofuran at -80 °C generates a high-spin (SFe = (5)/2) iron(III) superoxo adduct, 1. Mössbauer studies revealed that 1 is an exchange-coupled system, [Formula: see text], where SR = (1)/2 is the spin of the superoxo radical, of which the spectra were not well enough resolved to determine whether the coupling was ferromagnetic (S = 3 ground state) or antiferromagnetic (S = 2). The glass-forming 2-methyltetrahydrofuran solvent yields highly resolved Mössbauer spectra from which the following data have been extracted: (i) the ground state of 1 has S = 3 (J < 0); (ii) |J| > 15 cm(-1); (iii) the zero-field-splitting parameters are D = -1.1 cm(-1) and E/D = 0.02; (iv) the major component of the electric-field-gradient tensor is tilted ≈7° relative to the easy axis of magnetization determined by the MS = ±3 and ±2 doublets. The excited-state MS = ±2 doublet yields a narrow parallel-mode electron paramagnetic resonance signal at g = 8.03, which was used to probe the magnetic hyperfine splitting of (17)O-enriched O2. A theoretical model that considers spin-dependent electron transfer for the cases where the doubly occupied π* orbital of the superoxo ligand is either "in" or "out" of the plane defined by the bent Fe-OO moiety correctly predicts that 1 has an S = 3 ground state, in contrast to the density functional theory calculations for 1, which give a ground state with both the wrong spin and orbital configuration. This failure has been traced to a basis set superposition error in the interactions between the superoxo moiety and the adjacent five-membered rings of the BDPP ligand and signals a fundamental problem in the quantum chemistry of O2 activation.

  20. MRCI+Q calculations on spectroscopic properties of excited states of PbH including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Zhao, Shutao; Li, Rui; Zhang, Hua; Li, Huiquan

    2017-03-01

    The 10 Ʌ-S states associated with the lowest four dissociation limits of PbH radical have been studied utilizing configuration interaction method. For better accuracy, the Davidson correction, core-valence correlation and spin-orbit coupling effects are included. The potential energy curves of 10 Ʌ-S states and 18 Ω states have been obtained and characterized. The computed dipole moments of 10 Ʌ-S states are used to reveal the ionic characteristics of the Ʌ-S states. Finally, the transitional dipole moments of several bound Ω states and lifetimes of vibrational states trapped in excited bound Ω states are determined.

  1. Nonintrusive spectroscopic techniques for supersonic/hypersonic aerodynamics and combustion diagnostics

    NASA Technical Reports Server (NTRS)

    Exton, R. J.

    1992-01-01

    This paper presents an overview of the primary nonintrusive diagnostic techniques being developed by the NASA Langley Research Center to address the validation needs of Computational Fluid Dynamic (CFD) codes. The techniques include absorption in the UV and IR, Laser Induced Fluorescence, electron beam fluorescence, and a number of scattering techniques including Rayleigh, spontaneous Raman, and several coherent Raman spectroscopies. Most of the techniques are highly specialized, require complex data interpretation, and can satisfy only a few of the CFD needs. For these reasons, the evolving trend in flowfield diagnostics appears to favor a mode in which the diagnostic researcher, the experimental aerodynamicist, and the CFD community jointly define experiments based on the aeronautical requirements and on available diagnostic techniques.

  2. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Mohanty, B. P.; Saini, G. S. S.

    2016-02-01

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  3. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

    PubMed

    Singh, Gurpreet; Mohanty, B P; Saini, G S S

    2016-02-15

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Study on the interaction characteristics of cefamandole with bovine serum albumin by spectroscopic technique.

    PubMed

    Wang, Qian; Liu, Xuyang; Su, Ming; Shi, Zhihong; Sun, Hanwen

    2015-02-05

    The interaction of cefamandole with bovine serum albumin (BSA) was studied by fluorescence quenching in combination with UV-Vis spectroscopic method under near physiological conditions. The fluorescence quenching rate constants and binding constants for BSA-cefamandole system were determined at different temperatures. The fluorescence quenching of BSA by cefamandole is due to static quenching and energy transfer. The results of thermodynamic parameters, ΔH (-268.0 kJ mol(-1)), ΔS (-810.0 J mol(-1) K(-1)) and ΔG (-26.62 to -8.52 kJ mol(-1)), indicated that van der Waals interaction and hydrogen bonding played a major role for cefamandole-BSA association. The competitive experiments demonstrated that the primary binding site of cefamandole on BSA was located at site III in sub-domain IIIA of BSA. The distance between cefamandole and a tryptophane unit was estimated to be 1.18 nm based on the Förster resonance energy transfer theory. The binding constant (KA) of BSA-cefamandole at 298 K was 2.239×10(4) L mol(-1). Circular dichroism spectra, synchronous fluorescence and three-dimensional fluorescence studies showed that the presence of cefamandole could change the conformation of BSA during the binding process.

  5. Molecular structure and spectroscopic characterization of Carbamazepine with experimental techniques and DFT quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Suhasini, M.; Sailatha, E.; Gunasekaran, S.; Ramkumaar, G. R.

    2015-04-01

    A systematic vibrational spectroscopic assignment and analysis of Carbamazepine has been carried out by using FT-IR, FT-Raman and UV spectral data. The vibrational analysis were aided by electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP) performed with standard basis set 6-31G(d,p). Molecular equilibrium geometries, electronic energies, natural bond order analysis, harmonic vibrational frequencies and IR intensities have been computed. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED) by VEDA program. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λmax were determined by HF/6-311++G(d,p) Time-Dependent method. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. The restricted Hartree-Fock and density functional theory-based nuclear magnetic resonance (NMR) calculation procedure was also performed, and it was used for assigning the 13C and 1H NMR chemical shifts of Carbamazepine.

  6. Molecular structure and spectroscopic characterization of Carbamazepine with experimental techniques and DFT quantum chemical calculations.

    PubMed

    Suhasini, M; Sailatha, E; Gunasekaran, S; Ramkumaar, G R

    2015-04-15

    A systematic vibrational spectroscopic assignment and analysis of Carbamazepine has been carried out by using FT-IR, FT-Raman and UV spectral data. The vibrational analysis were aided by electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP) performed with standard basis set 6-31G(d,p). Molecular equilibrium geometries, electronic energies, natural bond order analysis, harmonic vibrational frequencies and IR intensities have been computed. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED) by VEDA program. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λmax were determined by HF/6-311++G(d,p) Time-Dependent method. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. The restricted Hartree-Fock and density functional theory-based nuclear magnetic resonance (NMR) calculation procedure was also performed, and it was used for assigning the (13)C and (1)H NMR chemical shifts of Carbamazepine. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Growth of ZnO thin films doped with (Mn & Co) by spin coating technique

    SciTech Connect

    Dhruvashi,; Rawat, Kusum; Shishodia, P. K.

    2016-05-06

    ZnO thin films co-doped with Mn and Co have been deposited on glass substrates by spin coating technique. Structural, optical and magnetic properties have been investigated as a function of dopant concentration. X-ray diffraction has confirmed the growth of c-axis oriented polycrystalline thin films. No impurity phases have been detected corresponding to metal oxides within the limitation of x-ray diffraction. The optical bandgap has been evaluated from tauc’s plots derived from the transmittance spectra in the wavelength range 350-900 nm. Surface morphology of the films has been observed by field emission scanning electron microscope. The field dependence of magnetization (M-H curve) measured by vibrating sample magnetometer shows the ferromagnetic behavior of the films at room temperature. The magnetization versus temperature (M-T) curve has also been measured under zero field cooled and field cooled conditions.

  8. Magnetic characterization of Fe-Al-B amorphous ribbons obtained by the melt spinning technique

    NASA Astrophysics Data System (ADS)

    García, J. A.; Carrizo, J.; Elbaile, L.; Rivas, M.; Crespo, R. D.; Martínez-García, J. C.

    2011-05-01

    The magnetic properties of a new amorphous material obtained by melt spinning technique is presented. The composition of the ribbon is Fe72Al14B14. The bulk hysteresis loops indicates that this ribbon is a soft magnetic material with a magnetic anisotropy along the longitudinal direction of the ribbon and an anisotropy constant of 1860 Jm-3. The value of the anisotropy is explained on the basis of the formation of directional order. The saturation magnetization results 1.12 T and the coercive field 18 Am-1. The surface magnetic properties show that the magnetic anisotropy is higher in the wheel-surface than in the air-surface. This result is explained considering the residual stress distribution in this kind of materials.

  9. Theoretical calculations on 12 Λ-S and 23 Ω states of CBr+ cation in the gas phase: Potential energy curves, spectroscopic parameters and spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Shi, Deheng; Niu, Xianghong; Sun, Jinfeng; Zhu, Zunlue

    2014-01-01

    The potential energy curves (PECs) of X1Σ+, a3Π, 13Σ+, 13Δ, 11Δ, 11Σ-, 13Σ-, 11Π, 21Σ+, 23Π, 21Π and 23Σ+ Λ-S states of CBr+ cation and corresponding 23 Ω states are calculated for the first time using the CASSCF method, which is followed by the internally contracted MRCI approach with the aug-cc-pVQZ basis set. All the Λ-S states involved are found to be bound and dissociate into the first dissociation limit of CBr+ cation. Of these Λ-S states, only the 13Σ+ and 13Σ- are inverted ones. The spin-orbit (SO) coupling is accounted for by the state interaction approach with the Breit-Pauli Hamiltonian. Core-valence correlation is included by a cc-pCVTZ basis set. Relativistic correction is calculated with the third-order Douglas-Kroll Hamiltonian approximation at the level of cc-pVQZ basis set. To obtain more reliable results, the PECs obtained by the MRCI calculations are corrected for size-extensivity errors by means of the Davidson modification. The PEC crossings of different Λ-S states are studied. With these PECs, the spectroscopic parameters of all the Λ-S and Ω states involved are obtained by fitting the first ten vibrational levels whenever available, which are calculated by solving the rovibrational Schrödinger equation using the Numerov's method. The spectroscopic parameters are compared with those reported in the literature. Excellent agreement is found between the present results and available measurements. In particular, the energy separation of 352.26 cm-1 between the a3Π0+ and the a3Π1 Ω states agrees well with the measurements of 369±8 cm-1, and the ωe results of 907.45 and 907.08 cm-1 for the a3Π0+ and a3Π1 Ω states are in excellent agreement with the measurements of 906±2 and 903±6 cm-1, respectively. These show that the spectroscopic parameters obtained in the present paper can be expected to be reliable predicted ones.

  10. Optimisation of pulsed and pseudo-continuous arterial spin labeling MRI techniques: A phantom study

    NASA Astrophysics Data System (ADS)

    Yusoff, Norain; Zukhi, Jihan; Rusli, Awatif; Zainon, Rafidah

    2017-05-01

    Arterial Spin Labeling (ASL) MRI is a non-invasive technique using a freely diffusible intrinsic tracer. The main objective of this study is to evaluate two different techniques of ASL MRI; pulsed ASL (PASL) and pseudo-continuous ASL (PCASL) in obtaining the best signal by manipulating the different imaging parameters. We used a fabricated Perspex flow phantom that is magnetically susceptible. The phantom has a straight tube that mimics carotid artery in adult patients and a U-shaped tube with 75% stenosis. We used a mixture of 60:40 distilled water and glycerol respectively as a substitute to blood. The fabricated phantom was scanned with 1.5T and 3T MRI Scanner using PCASL technique and PASL respectively. Two main imaging parameters were studied which were the field of view (FOV) and slice thickness (ST) to obtain the signal-to-noise ratio (SNR) of the region of interests. The 1.5 T PCASL technique gave SNR values of (13, 22, 30.1) for ST (5, 7, 9 mm) and FOV 240. When higher FOV = 320 was selected, the SNR values were (26.8, 15, 37) for different ST (5, 7, 9 mm). The 3.0 T PASL technique gave the SNR values of (9, 9.3, 11) for ST (5, 7, 9mm) and FOV 240mm. In the higher FOV = 320 mm, we obtained SNR values of (15.2, 17.5, 37.2) for ST (5, 7, 9 mm). As a conclusion, the images quality which can be measured by SNR value is affected by types of ASL and also different parameters.

  11. Monitoring PDT effects in murine tumors by spectroscopic and imaging techniques

    NASA Astrophysics Data System (ADS)

    Ramaprasad, Subbaraya; Rzepka, Elzbieta; Pi, Jiaxiong; Joshi, Shantaram S.; Dobhal, Mahabeer; Missert, Joseph; Pandey, Ravindra K.

    2004-04-01

    The changes in the tumor that occur following photodynamic therapy (PDT) were studied using a small animal MR imager operating at 7Tesla. The animal model used in these studies was mice bearing radiation induced fibrosarcoma (RIF) tumor on the foot dorsum. The mice were injected with 10μM/kg of one of the photosensitizers: (1) Photofrin, (2) Non-fluorinated porphyrin photosensitizer (DOD-1), (3) Fluorinated porphyrin photosensitizer (DOD-2) and, (4) Fluorinated chlorin photosensitizer (DOD-6). Laser light at 630 or 650 nm (150 mW/cm2, 270 joules/cm2) was delivered to the tumor at 2-24 hours of photosensitizer administration. The MR spectroscopic and imaging examination of the tumors involved both the 1H and 31P nuclei. The tumor bioenergetics was measured by 31P spectroscopy. The water proton relaxivity and diffusion measurements were used to obtain local changes in different regions of the tumor. Changes in 31P MR spectra were observed following PDT using Photofrin and fluorinated chlorin sensitizer (DOD-6). However, no significant changes were observed when the fluorinated porphyrin and its nonfluorinated analog were used. The PDT induced changes in tumor volumes showed significant tumor regression with Photofrin, fluorinated porphyrin and chlorin sensitizers. No tumor regression was observed with the non labeled porphyrin sensitizer and the growth profile followed the general pattern of unperturbed tumors. Serial noninvasive measurements of tumor response to PDT are measurable by both MRI and MRS. The MR derived parameters that are characteristic of the tumor status before and after the therapy are discussed here.

  12. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas

    NASA Astrophysics Data System (ADS)

    Dutra, E. C.; Koch, J. A.; Presura, R.; Angermeier, W. A.; Darling, T.; Haque, S.; Mancini, R. C.; Covington, A. M.

    2016-11-01

    Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

  13. Coupling spectroscopic and chromatographic techniques for evaluation of the depositional history of hydrocarbons in a subtropical estuary.

    PubMed

    Martins, César C; Doumer, Marta E; Gallice, Wellington C; Dauner, Ana Lúcia L; Cabral, Ana Caroline; Cardoso, Fernanda D; Dolci, Natiely N; Camargo, Luana M; Ferreira, Paulo A L; Figueira, Rubens C L; Mangrich, Antonio S

    2015-10-01

    Spectroscopic and chromatographic techniques can be used together to evaluate hydrocarbon inputs to coastal environments such as the Paranaguá estuarine system (PES), located in the SW Atlantic, Brazil. Historical inputs of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analyzed using two sediment cores from the PES. The AHs were related to the presence of biogenic organic matter and degraded oil residues. The PAHs were associated with mixed sources. The highest hydrocarbon concentrations were related to oil spills, while relatively low levels could be attributed to the decrease in oil usage during the global oil crisis. The results of electron paramagnetic resonance were in agreement with the absolute AHs and PAHs concentrations measured by chromatographic techniques, while near-infrared spectroscopy results were consistent with unresolved complex mixture (UCM)/total n-alkanes ratios. These findings suggest that the use of a combination of techniques can increase the accuracy of assessment of contamination in sediments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Spectroscopic capture and reactivity of a low-spin cobalt(IV)-oxo complex stabilized by binding redox-inactive metal ions.

    PubMed

    Hong, Seungwoo; Pfaff, Florian F; Kwon, Eunji; Wang, Yong; Seo, Mi-Sook; Bill, Eckhard; Ray, Kallol; Nam, Wonwoo

    2014-09-22

    High-valent cobalt-oxo intermediates are proposed as reactive intermediates in a number of cobalt-complex-mediated oxidation reactions. Herein we report the spectroscopic capture of low-spin (S=1/2) Co(IV)-oxo species in the presence of redox-inactive metal ions, such as Sc(3+), Ce(3+), Y(3+), and Zn(2+), and the investigation of their reactivity in C-H bond activation and sulfoxidation reactions. Theoretical calculations predict that the binding of Lewis acidic metal ions to the cobalt-oxo core increases the electrophilicity of the oxygen atom, resulting in the redox tautomerism of a highly unstable [(TAML)Co(III)(O˙)](2-) species to a more stable [(TAML)Co(IV)(O)(M(n+))] core. The present report supports the proposed role of the redox-inactive metal ions in facilitating the formation of high-valent metal-oxo cores as a necessary step for oxygen evolution in chemistry and biology.

  15. Spectroscopic Capture and Reactivity of a Low-Spin Cobalt(IV)-Oxo Complex Stabilized by Binding Redox-Inactive Metal Ions

    PubMed Central

    Wang, Yong; Seo, Mi-Sook; Bill, Eckhard; Ray, Kallol; Nam, Wonwoo

    2015-01-01

    High-valent cobalt-oxo intermediates are proposed as reactive intermediates in a number of cobalt complex-mediated oxidation reactions. Herein we report the spectroscopic capture of low-spin (S = 1/2) Co(IV)-oxo species in the presence of redox-inactive metal ions, such as Sc3+, Ce3+, Y3+, and Zn2+ and investigation of their reactivity in C-H bond activation and sulfoxidation reactions. Theoretical calculations predict that the binding of Lewis-acidic metal ions to the cobalt-oxo core increases the electrophilicity of the oxygen atom, resulting in the redox tautomerism of a highly unstable [(TAML)CoIII-(O•)]2− species to a more stable [(TAML)CoIV-(O)(Mn+)] core. The present report supports the proposed role of the redox-inactive metal ions in facilitating formation of high-valent metal-oxo cores as a necessary step for oxygen evolution in chemistry and biology. PMID:25081948

  16. Spatially-resolved spectroscopic technique for measuring optical properties of food

    USDA-ARS?s Scientific Manuscript database

    Quantification of optical properties is important to understand light interaction with biological materials, and to develop effective optical sensing techniques for property characterization and quality measurement of food products. This chapter reviews spatially-resolved method, with the focus on f...

  17. Advanced techniques for high resolution spectroscopic observations of cosmic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Matteson, J. L.; Pelling, M. R.; Peterson, L. E.; Lin, R. P.; Anderson, K. A.; Pehl, R. H.; Hurley, K. C.; Vedrenne, G.; Sniel, M.; Durouchoux, P.

    1985-01-01

    An advanced gamma-ray spectrometer that is currently in development is described. It will obtain a sensitivity of 0.0001 ph/sq cm./sec in a 6 hour balloon observation and uses innovative techniques for background reduction and source imaging.

  18. Reflective and photoacoustic infrared spectroscopic techniques in assessment of binding media in paintings

    NASA Astrophysics Data System (ADS)

    Łojewski, Tomasz; Bagniuk, Jacek; Kołodziej, Andrzej; Łojewska, Joanna

    2011-11-01

    This study proposes a method to estimate the lipid content in binding media in paintings that can be used at any laboratory equipped with an infrared spectrometer. The lipid content estimator, termed greasiness index (GI), is defined as a ratio of lipid ν(C=O) and protein amide I bands at 1743 and 1635 cm-1, respectively. Three Fourier transform infrared (FTIR) sampling techniques were evaluated for GI determination: reflective attenuated total reflection—ATR, specular reflection microscopy— μSR and photoacoustic—PAS. A set of model painting samples containing three tempera binding media (casein, egg, egg + oil), seven pigments and one varnish type were used in the study. Multivariate analysis was used to evaluate the resulting data. A good reproducibility of GI was obtained by ATR and PAS but not with μSR. The discriminative power of the technique is higher for unvarnished samples, but, generally, the GI estimator can be used for the categorisation of binding media in large populations of painting samples analysed with the same FTIR technique (sampling technique, detection, etc.).

  19. Mapping of cerebral perfusion territories using territorial arterial spin labeling: techniques and clinical application.

    PubMed

    Hartkamp, Nolan S; Petersen, Esben T; De Vis, Jill B; Bokkers, Reinoud P H; Hendrikse, Jeroen

    2013-08-01

    A knowledge of the exact cerebral perfusion territory which is supplied by any artery is of great importance in the understanding and diagnosis of cerebrovascular disease. The development and optimization of territorial arterial spin labeling (T-ASL) MRI techniques in the past two decades have made it possible to visualize and determine the cerebral perfusion territories in individual patients and, more importantly, to do so without contrast agents or otherwise invasive procedures. This review provides an overview of the development of ASL techniques that aim to visualize the general cerebral perfusion territories or the territory of a specific artery of interest. The first efforts of T-ASL with pulsed, continuous and pseudo-continuous techniques are summarized and subsequent clinical studies using T-ASL are highlighted. In the healthy population, the perfusion territories of the brain-feeding arteries are highly variable. This high variability requires special consideration in specific patient groups, such as patients with cerebrovascular disease, stroke, steno-occlusive disease of the large arteries and arteriovenous malformations. In the past, catheter angiography with selective contrast injection was the only available method to visualize the cerebral perfusion territories in vivo. Several T-ASL methods, sometimes referred to as regional perfusion imaging, are now available that can easily be combined with conventional brain MRI examinations to show the relationship between the cerebral perfusion territories, vascular anatomy and brain infarcts or other pathology. Increased availability of T-ASL techniques on clinical MRI scanners will allow radiologists and other clinicians to gain further knowledge of the relationship between vasculature and patient diagnosis and prognosis. Treatment decisions, such as surgical revascularization, may, in the near future, be guided by information provided by T-ASL MRI in close correlation with structural MRI and quantitative

  20. Artificial tektites: an experimental technique for capturing the shapes of spinning drops

    NASA Astrophysics Data System (ADS)

    Baldwin, K. A.

    2014-12-01

    Tektites are small stones formed from rapidly cooling drops of molten rock ejected from high velocity asteroid impacts with the Earth, that freeze into a myriad of shapes during flight. Many splash-form tektites have an elongated or dumb-bell shape owing to their rotation prior to solidification[1]. Here we present a novel method for creating 'artificial tektites' from spinning drops of molten wax, using diamagnetic levitation to suspend the drops[2]. We find that the solid wax models produced this way are the stable equilibrium shapes of a spinning liquid droplet held together by surface tension. In addition to the geophysical interest in tektite formation, the stable equilibrium shapes of liquid drops have implications for many physical phenomena, covering a wide range of length scales, from nuclear physics (e.g. in studies of rapidly rotating atomic nuclei), to astrophysics (e.g. in studies of the shapes of astronomical bodies such as asteroids, rapidly rotating stars and event horizons of rotating black holes). For liquid drops bound by surface tension, analytical and numerical methods predict a series of stable equilibrium shapes with increasing angular momentum. Slowly spinning drops have an oblate-like shape. With increasing angular momentum these shapes become secularly unstable to a series of triaxial pseudo-ellipsoids that then evolve into a family of two-lobed 'dumb-bell' shapes as the angular momentum is increased still further. Our experimental method allows accurate measurements of the drops to be taken, which are useful to validate numerical models. This method has provided a means for observing tektite formation, and has additionally confirmed experimentally the stable equilibrium shapes of liquid drops, distinct from the equivalent shapes of rotating astronomical bodies. Potentially, this technique could be applied to observe the non-equilibrium dynamic processes that are also important in real tektite formation, involving, e.g. viscoelastic

  1. Segmental dynamics of polyethylene-alt-propylene studied by NMR spin echo techniques

    NASA Astrophysics Data System (ADS)

    Lozovoi, A.; Mattea, C.; Hofmann, M.; Saalwaechter, K.; Fatkullin, N.; Stapf, S.

    2017-06-01

    Segmental dynamics of a highly entangled melt of linear polyethylene-alt-propylene with a molecular weight of 200 kDa was studied with a novel proton nuclear magnetic resonance (NMR) approach based upon 1H → 2H isotope dilution as applied to a solid-echo build-up function ISE(t), which is constructed from the NMR spin echo signals arising from the Hahn echo (HE) and two variations of the solid-echo pulse sequence. The isotope dilution enables the separation of inter- and intramolecular contributions to this function and allows one to extract the segmental mean-squared displacements in the millisecond time range, which is hardly accessible by other experimental methods. The proposed technique in combination with time-temperature superposition yields information about segmental translation in polyethylene-alt-propylene over 6 decades in time from 10-6 s up to 1 s. The time dependence of the mean-squared displacement obtained in this time range clearly shows three regimes of power law with exponents, which are in good agreement with the tube-reptation model predictions for the Rouse model, incoherent reptation and coherent reptation regimes. The results at short times coincide with the fast-field cycling relaxometry and neutron spin echo data, yet, significantly extending the probed time range. Furthermore, the obtained data are verified as well by the use of the dipolar-correlation effect on the Hahn echo, which was developed before by the co-authors. At the same time, the amplitude ratio of the intermolecular part of the proton dynamic dipole-dipole correlation function over the intramolecular part obtained from the experimental data is not in agreement with the predictions of the tube-reptation model for the regimes of incoherent and coherent reptation.

  2. Parameter Identification of Spin-Stabilized Projectiles Using a Modified Nowton-Raphson Minimization Technique

    NASA Astrophysics Data System (ADS)

    Kuo, Zeal-Sain; Huang, Hsiao-Yu

    A modified Newton-Raphson minimization technique for determining aerodynamic coefficients and stability derivatives of spin-stabilized projectiles with a six-degree-of-freedom nonlinear dynamical model was developed. The dynamical model for the projectiles is constructed having process noise in the system, and the instrumentation noise of the system outputs is simulated by a data model statistically similar to the measured data. The state equations of the dynamical system are continuous types while the measurement data are discrete. A continuous-discrete estimation model for the motion of the projectiles is constructed in this paper. The state variables of the system were estimated by the extended Kalman filter, and the system parameters were identified by the modified Newton-Raphson technique based on the maximum likelihood criterion. Research results show that parts of the parameters can be identified under proper noise intensity. However, the accuracy of identification is strongly influenced by both process and measurement noise, Moreover, parameter sensitivity to the system behavior is crucial for the success of identification. Two typical aerodynamic characteristics of projectiles, 105 and 20mm, are imposed to investigate the applicability of state estimation and parameter identification. It is found that the drag coefficient of zero angle-of-attack and the rolling moment derivative and identified with effective accuracy in a wide range of noise levels. On the other hand, other parameters are more difficult to identify, but the causes of deficiency for particular parameters in identification are discussed.

  3. 3D GRASE PROPELLER: Improved Image Acquisition Technique for Arterial Spin Labeling Perfusion Imaging

    PubMed Central

    Tan, Huan; Hoge, W. Scott; Hamilton, Craig A.; Günther, Matthias; Kraft, Robert A.

    2014-01-01

    Arterial spin labeling (ASL) is a non-invasive technique that can quantitatively measure cerebral blood flow (CBF). While traditionally ASL employs 2D EPI or spiral acquisition trajectories, single-shot 3D GRASE is gaining popularity in ASL due to inherent SNR advantage and spatial coverage. However, a major limitation of 3D GRASE is through-plane blurring caused by T2 decay. A novel technique combining 3D GRASE and a PROPELLER trajectory (3DGP) is presented to minimize through-plane blurring without sacrificing perfusion sensitivity or increasing total scan time. Full brain perfusion images were acquired at a 3×3×5mm3 nominal voxel size with Q2TIPS-FAIR as the ASL preparation sequence. Data from 5 healthy subjects was acquired on a GE 1.5T scanner in less than 4 minutes per subject. While showing good agreement in CBF quantification with 3D GRASE, 3DGP demonstrated reduced through-plane blurring, improved anatomical details, high repeatability and robustness against motion, making it suitable for routine clinical use. PMID:21254211

  4. New spectroscopic tools and techniques for characterizing M dwarfs and discovering their planets in the near-infrared

    NASA Astrophysics Data System (ADS)

    Terrien, Ryan C.

    M dwarfs are the least massive and most common stars in the Galaxy. Due to their prevalence and long lifetimes, these diminutive stars play an outsize role in several fields of astronomical study. In particular, it is now known that they commonly host planetary systems, and may be the most common hosts of Earth-size, rocky planets in the habitable zone. A comprehensive understanding of M dwarfs is crucial for understanding the origins and conditions of their planetary systems, including their potential habitability. Such an understanding depends on methods for precisely and accurately measuring their properties. These tools have broader applicability as well, underlying the use of M dwarfs as fossils of Galactic evolution, and helping to constrain the structures and interiors of these stars. The measurement of the fundamental parameters of M dwarfs is encumbered by their spectral complexity. Unlike stars of spectral type F, G, or K that are similar to our G type Sun, whose spectra are dominated by continuum emission and atomic features, the cool atmospheres of M dwarfs are dominated by complex molecular absorption. Another challenge for studies of M dwarfs is that these stars are optically faint, emitting much of their radiation in the near-infrared (NIR). The availability and performance of NIR spectrographs have lagged behind those of optical spectrographs due to the challenges of producing low-noise, high-sensitivity NIR detector arrays, which have only recently become available. This thesis discusses two related lines of work that address these challenges, motivated by the development of the Habitable Zone Planet Finder (HPF), a NIR radial velocity (RV) spectrograph under development at Penn State that will search for and confirm planets around nearby M dwarfs. This work includes the development and application of new NIR spectroscopic techniques for characterizing M dwarfs, and the development and optimization of new NIR instrumentation for HPF. The first line

  5. Spectroscopic, Structural, and Functional Characterization of the Alternative Low-Spin State of Horse Heart Cytochrome c

    PubMed Central

    Mugnol, Katia C. U.; Ando, Rômulo A.; Nagayasu, Rafael Y.; Faljoni-Alario, Adelaide; Brochsztain, Sergio; Santos, Paulo S.; Nascimento, Otaciro R.; Nantes, Iseli L.

    2008-01-01

    The alternative low-spin states of Fe3+ and Fe2+ cytochrome c induced by SDS or AOT/hexane reverse micelles exhibited the heme group in a less rhombic symmetry and were characterized by electron paramagnetic resonance, UV-visible, CD, magnetic CD, fluorescence, and Raman resonance. Consistent with the replacement of Met80 by another strong field ligand at the sixth heme iron coordination position, Fe3+ ALSScytc exhibited 1-nm Soret band blue shift and ɛ enhancement accompanied by disappearance of the 695-nm charge transfer band. The Raman resonance, CD, and magnetic CD spectra of Fe3+ and Fe2+ ALSScytc exhibited significant changes suggestive of alterations in the heme iron microenvironment and conformation and should not be assigned to unfold because the Trp59 fluorescence remained quenched by the neighboring heme group. ALSScytc was obtained with His33 and His26 carboxyethoxylated horse cytochrome c and with tuna cytochrome c (His33 replaced by Asn) pointing out Lys79 as the probable heme iron ligand. Fe3+ ALSScytc retained the capacity to cleave tert-butylhydroperoxide and to be reduced by dithiothreitol and diphenylacetaldehyde but not by ascorbate. Compatible with a more open heme crevice, ALSScytc exhibited a redox potential ∼200 mV lower than the wild-type protein (+220 mV) and was more susceptible to the attack of free radicals. PMID:18227133

  6. Spectroscopic evidence for negative electronic compressibility in a quasi-three-dimensional spin-orbit correlated metal.

    PubMed

    He, Junfeng; Hogan, T; Mion, Thomas R; Hafiz, H; He, Y; Denlinger, J D; Mo, S-K; Dhital, C; Chen, X; Lin, Qisen; Zhang, Y; Hashimoto, M; Pan, H; Lu, D H; Arita, M; Shimada, K; Markiewicz, R S; Wang, Z; Kempa, K; Naughton, M J; Bansil, A; Wilson, S D; He, Rui-Hua

    2015-06-01

    Negative compressibility is a sign of thermodynamic instability of open or non-equilibrium systems. In quantum materials consisting of multiple mutually coupled subsystems, the compressibility of one subsystem can be negative if it is countered by positive compressibility of the others. Manifestations of this effect have so far been limited to low-dimensional dilute electron systems. Here, we present evidence from angle-resolved photoemission spectroscopy (ARPES) for negative electronic compressibility (NEC) in the quasi-three-dimensional (3D) spin-orbit correlated metal (Sr1-xLax)3Ir2O7. Increased electron filling accompanies an anomalous decrease of the chemical potential, as indicated by the overall movement of the deep valence bands. Such anomaly, suggestive of NEC, is shown to be primarily driven by the lowering in energy of the conduction band as the correlated bandgap reduces. Our finding points to a distinct pathway towards an uncharted territory of NEC featuring bulk correlated metals with unique potential for applications in low-power nanoelectronics and novel metamaterials.

  7. Murillo's paintings revealed by spectroscopic techniques and dedicated laboratory-made micro X-ray diffraction.

    PubMed

    Duran, A; Siguenza, M B; Franquelo, M L; Jimenez de Haro, M C; Justo, A; Perez-Rodriguez, J L

    2010-06-25

    This paper describes one of the first case studies using micro-diffraction laboratory-made systems to analyse painting cross-sections. Pigments, such as lead white, vermilion, red ochre, red lac, lapis lazuli, smalt, lead tin yellow type I, massicot, ivory black, lamp black and malachite, were detected in cross-sections prepared from six Bartolomé Esteban Murillo paintings by micro-Raman and micro-XRD combined with complementary techniques (optical microscopy, SEM-EDS, and FT-IR). The use of micro-XRD was necessary due to the poor results obtained with conventional XRD. In some cases, pigment identification was only possible by combining results from the different analytical techniques utilised in this study. Copyright 2010 Elsevier B.V. All rights reserved.

  8. Neutron Stimulated Emission Computed Tomography: A New Technique for Spectroscopic Medical Imaging

    NASA Astrophysics Data System (ADS)

    Kapadia, A. J.

    Neutron stimulated emission computed tomography (NSECT) is being developed as a new medical-imaging technique to quantify spatial distributions of elements in a sample through inelastic scattering of fast neutrons and detection of the resulting gamma rays. It has the potential to diagnose several disorders in the human body that are characterized by changes in element concentration in the diseased tissue. NSECT is sensitive to several naturally occurring elements in the human body that demonstrate concentration changes in the presence of diseases. NSECT, therefore, has the potential to noninvasively diagnose such disorders with radiation dose that is comparable to other ionizing imaging modalities. This chapter discusses the development and progress of NSECT and presents an overview of the current status of the imaging technique.

  9. Microsampling techniques for infrared spectroscopic analysis of lunar and terrestrial minerals

    NASA Technical Reports Server (NTRS)

    Estep, P. A.; Kovach, J. J.; Karr, C.

    1973-01-01

    Microsampling techniques have been developed for infrared analysis of single mineral grains from lunar rocks and dusts, allowing a detailed molecular structure characterization of these complex fine-grained samples. The methods include special devices for isolating single grains, preparing micropellets from the grains, and obtaining in situ microspecular reflectance spectra from grains in polished rock samples. Although specifically developed for the work on lunar samples, the special techniques for single grain infrared analysis were found to be equally useful in studies of complex terrestrial mineral samples. For example, infrared microanalysis has contributed substantially in solving problems concerned with our natural resources, such as the structural characterization of minerals from commercial iron ores, marine deposits, coal, and fly ash derived from coal.

  10. Microsampling techniques for infrared spectroscopic analysis of lunar and terrestrial minerals

    NASA Technical Reports Server (NTRS)

    Estep, P. A.; Kovach, J. J.; Karr, C.

    1973-01-01

    Microsampling techniques have been developed for infrared analysis of single mineral grains from lunar rocks and dusts, allowing a detailed molecular structure characterization of these complex fine-grained samples. The methods include special devices for isolating single grains, preparing micropellets from the grains, and obtaining in situ microspecular reflectance spectra from grains in polished rock samples. Although specifically developed for the work on lunar samples, the special techniques for single grain infrared analysis were found to be equally useful in studies of complex terrestrial mineral samples. For example, infrared microanalysis has contributed substantially in solving problems concerned with our natural resources, such as the structural characterization of minerals from commercial iron ores, marine deposits, coal, and fly ash derived from coal.

  11. Innovative combination of spectroscopic techniques to reveal nanoparticle fate in a crop plant

    NASA Astrophysics Data System (ADS)

    Larue, Camille; Castillo-Michel, Hiram; Stein, Ricardo J.; Fayard, Barbara; Pouyet, Emeline; Villanova, Julie; Magnin, Valérie; Pradas del Real, Ana-Elena; Trcera, Nicolas; Legros, Samuel; Sorieul, Stéphanie; Sarret, Géraldine

    2016-05-01

    Nanotechnology is the new industrial revolution of our century. Its development leads to an increasing use of nanoparticles and thus to their dissemination. Their fate in the environment is of great concern and especially their possible transfer in trophic chains might be an issue for food safety. However, so far our knowledge on this topic has been restricted by the lack of appropriate techniques to characterize their behavior in complex matrices. Here, we present in detail the use of cutting-edge beam-based techniques for nanoparticle in situ localization, quantification and speciation in a crop plant species (Lactuca sativa). Lettuce seedlings have been exposed to TiO2 and Ag nanoparticles and analyzed by inductively coupled plasma spectrometry, micro-particle induced X-ray emission coupled to Rutherford backscattering spectroscopy on nuclear microprobe, micro-X-ray fluorescence spectroscopy and X-ray absorption near edge structure spectroscopy. The benefits and drawbacks of each technique are discussed, and the types of information that can be drawn, for example on the translocation to edible parts, change of speciation within the plant, detoxification mechanisms, or impact on the plant ionome, are highlighted. Such type of coupled approach would be an asset for nanoparticle risk assessment.

  12. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in Z-pinch plasmas

    NASA Astrophysics Data System (ADS)

    Dutra, Eric; Presura, Radu; Covington, Aaron; Mancini, Roberto; Darling, Timothy; Angermeier, William

    2016-10-01

    Visible spectroscopic techniques are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. Experiments were conducted at the University of Nevada (Reno) at the Nevada Terawatt Facility (NTF) using the 1 MA Z-pinch (Zebra). The research explored the optical emission of Al III doublet, 4P 2P3/2 to 4S 2S1/2 and 4P 2P1/2 to 4s 2S1/2 transitions and used it to measure Zeeman, Stark, and Doppler broadened emission. The initial parameters for the line shape code are varied to simulate emission spectra. The simulated spectra are compared to experimental results. These results are used to infer temperature, electron density, and B-fields in the magnetized plasma.

  13. Chemical and morphological changes in hydrochars derived from microcrystalline cellulose and investigated by chromatographic, spectroscopic and adsorption techniques.

    PubMed

    Diakité, Mamadou; Paul, Andrea; Jäger, Christian; Pielert, Judith; Mumme, Jan

    2013-12-01

    Hydrothermal carbonization (HTC) can be used for converting the biomass into a carbon-rich material, whose application as a fuel requires higher heating value, whereas soil amendment needs stable carbon. This work was focused on the characterization of hydrochars derived from microcrystalline cellulose. The chars were investigated using elemental analysis, Brunauer-Emmett-Teller technique, nuclear magnetic resonance spectroscopy, Raman, Fourier transform infrared, and electron spin resonance spectroscopy. Severity in temperature between 230 and 270°C with reaction times between 2 and 10 h only affect the carbon content moderately. The results show that aromatization of HTC chars correlates well with temperature, which was further supported by the increase of organic radicals with decreasing g values at higher temperatures. Based on these results, the energetic use of chars favors mild HTC (T<230°C and t≤6 h), while the soil amendement favors serve conditions (T≥230°C, and t>6 h).

  14. The Analysis of Information Exchange Capability for Battlefield Networks Using M&S Techniques of the NetSPIN

    DTIC Science & Technology

    2013-06-01

    elements in a battlefield. To solve these problems, developed countries such as USA or EU have been made use of network M & S (Modeling and Simulation... M & S Techniques based on the Interworking of a Real System for the Interoperability T&E”, Korea Military Science Technology Conference, 2010. [5...Capability for Battlefield Networks using M & S techniques of the NetSPIN 19-21. Jun. 2013 A f D f D l tgency or e ense eve opmen Defense Cyber Warfare

  15. Development and applications of laser spectroscopic techniques related to combustion diagnostics

    NASA Astrophysics Data System (ADS)

    Aldén, Marcus

    2006-07-01

    Thanks to features as non-intrusiveness combined with high spatial and temporal resolution, various laser diagnostic techniques have during the last decades become of utmost importance for characterization of combustion related phenomena. In the following presentation some further development of the techniques will be highlighted aiming at a) surface temperatures using Thermographic Phosphors, TP, b) species specific, spatially and temporally resolved detection of species absorbing in the IR spectral region using polarization spectroscopy and Laser-induced fluorescence, and finally c) high speed visualization using a special designed laser system in combination with a framing camera. In terms of surface thermometry, Thermographic Phosphors have been used for many years for temperature measurements on solid surfaces. We have during the last years further developed and applied this technique for temperature measurements on burning surfaces and on materials going through phase shifts, e.g. pyrolysis and droplets. The basic principle behind this technique is to apply micron size particles to the surface of interest. By exciting the TP with a short pulse UV laser (ns), the phosphorescence will exhibit a behaviour where the spectral emission as well as the temporal decay are dependent on the temperature. It is thus possible to measure the temperature both in one and two dimensions. The presentation will include basic description of the technique as well as various applications, e.g in fire science, IC engines and gasturbines. Several of the species of interest for combustion/flow diagnostics exhibit a molecular structure which inhibits the use of conventional laser-induced fluorescence for spatially and spectrally resolved measurements. We have during the last years investigated the use of excitation and detection in the infrared region of the spectrum. Here, it is possible to detect both carbonmono/dioxide, water as well as species specific hydrocarbons. The techniques

  16. THz spectroscopic studies of materials using the FTIR technique: experiment and simulation

    NASA Astrophysics Data System (ADS)

    Lepodise, Lucia Malebogo

    2014-04-01

    Terahertz (THz) radiation has remained the least developed part of the electromagnetic spectrum for quite a long time and thus it was traditionally known as the 'terahertz gap'. The progress of research in this field has been hindered by lack of powerful sources and detectors as compared to both the sources and detectors for the electronic and optical sides of the terahertz radiation region. However, the research on the THz field has intensified in recent years due to a number of emerging interesting technologies and owing to its unique properties. It has several advantages over its counterparts like X-ray and hence it has attracted much interest in a variety of applications scientifically and commercially. THz work has been recently focused in the low frequency region (0.1-3 THz). This is the region where most of the THz spectral features of many materials lie. Studies in this frequency range have been seen revolutionizing the THz field giving it a pool of potential applications which are still yet to be realized. The low frequency THz region (0.1-3 THz) is accessible through the use of the THz-TDS technique and this technique is the mostly used to date. The value of this method is evident throughout the work published in terahertz research and thus its use prevails over other techniques. Many materials show some spectral features in the much higher frequency region (up to 21 THz), but however this frequency range has not attracted much attention in comparison to the low frequency range which of course is more rich in THz spectral features. Furthermore, although the low frequency THz region has been quite extensively studied, the concentration has been at room temperature with a few temperature-dependence studies mostly done at particular temperatures rather than over a wide range.

  17. Raman spectroscopic studies of thin film carbon nanostructures deposited using electro deposition technique

    NASA Astrophysics Data System (ADS)

    Dayal, Saurabh; Sasi, Arshali; Jhariya, Sapna; Sasikumar, C.

    2016-05-01

    In the present work our focus is to synthesize carbon nanostructures (CNS) by electro deposition technique without using any surface pretreatment or catalyst preparation before CNS formation. The process were carried out at significantly low voltage and at low temperature as reported elsewhere. Further the samples were characterized using different characterization tools such as SEM and Raman spectroscopy. The SEM results showed the fibres or tubular like morphology. Raman spectra shows strong finger print at 1600 cm-1 (G peak), 1350 cm-1 (D peak) along with the radial breathing mode (RBM) between 150cm-1 to 300 cm-1. This confirms the formation of tubular carbon nanostructures.

  18. The analytical investigations of ancient pottery from Kaveripakkam, Vellore dist, Tamilnadu by spectroscopic techniques.

    PubMed

    Ravisankar, R; Naseerutheen, A; Annamalai, G Raja; Chandrasekaran, A; Rajalakshmi, A; Kanagasabapathy, K V; Prasad, M V R; Satpathy, K K

    2014-01-01

    Analytical investigations using Fourier Transform infrared spectroscopy (FT-IR), Powder X-ray Diffraction (PXRD), Thermal Analysis (TG-DTA), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) were carried out on ancient pottery fragments from Kaveripakkam, in order to outline manufacturing skills, technology information, firing condition and temperature of potteries. The whole set of data showed the firing temperature in the range of 800-900°C. The analytical characterization of the potsherds, by different complimentary techniques has allowed to identifying the raw materials and technology applied by the ancient artisans.

  19. The analytical investigations of ancient pottery from Kaveripakkam, Vellore dist, Tamilnadu by spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Ravisankar, R.; Naseerutheen, A.; Raja Annamalai, G.; Chandrasekaran, A.; Rajalakshmi, A.; Kanagasabapathy, K. V.; Prasad, M. V. R.; Satpathy, K. K.

    2014-03-01

    Analytical investigations using Fourier Transform infrared spectroscopy (FT-IR), Powder X-ray Diffraction (PXRD), Thermal Analysis (TG-DTA), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) were carried out on ancient pottery fragments from Kaveripakkam, in order to outline manufacturing skills, technology information, firing condition and temperature of potteries. The whole set of data showed the firing temperature in the range of 800-900 °C. The analytical characterization of the potsherds, by different complimentary techniques has allowed to identifying the raw materials and technology applied by the ancient artisans.

  20. Micro-spectroscopic techniques applied to characterization of varnished archeological findings

    NASA Astrophysics Data System (ADS)

    Barone, G.; Ioppolo, S.; Majolino, D.; Migliardo, P.; Ponterio, R.

    2000-04-01

    This work reports an analysis on terracotta varnished finding recovered in east Sicily area (Messina). We have performed FTIR micro-spectroscopy and electronic microscopy (SEM)measurements in order to recognize the elemental constituents of the varnished surfaces. Furthermore, for all the samples, a study on the bulk has been performed by Fourier Transform Infrared Absorption. The analyzed samples consist of a number of pottery fragments belonging to archaic and classical ages, varnished in black and red colors. The obtained data furnished useful information about composition of decorated surfaces and bulk matrixes, about baking temperature, manufacture techniques and alteration mechanisms of findings due to the long burial.

  1. Refining Techniques for the Spectroscopic Detection of Reflected Light from Exoplanets

    NASA Astrophysics Data System (ADS)

    Roy, Arpita; Bender, Chad; Mahadevan, Suvrath

    2015-12-01

    The detection of reflected light from exoplanets provides a direct measure of planetary mass as well as a powerful probe of atmospheric composition and albedo. However, close-in giant planets which provide the largest planet-to-star flux ratios are dim in the optical. With contrasts at the level of 10^-5, the direct detection of these present a severe technical challenge to current instruments, and require both large aperture telescopes for high signal-to-noise ratio observations, and a stabilized spectrograph for stable instrument profiles. Leveraging the heritage and stability of the HARPS spectrograph, Martins et al (2015) recently published evidence of a direct detection of the historic exoplanet 51 Peg b, using the stellar mask cross-correlation technique. We attempt to expand upon their results with independent spectral and CCF reductions, using a two-template cross-correlation technique that can potentially be tuned to match the planetary signal and probe models of the albedo. By cross-correlating against a spectrum rather than a mask, we access the full information content in the lines, but must ensure proper telluric correction to mitigate the possibility of overwhelming the small planetary signal with terrestrial features. We are on the verge of confidently recovering planetary albedos for close-in giant planets, while also refining predictive and analytical tools that will come into their full capability with the arrival of the next generation of planet characterizing instruments, such as ESPRESSO on VLT and HIRES on E-ELT.

  2. Analysis of the binding interaction in uric acid - Human hemoglobin system by spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Makarska-Bialokoz, Magdalena

    2017-05-01

    The binding interaction between human hemoglobin and uric acid has been studied for the first time, by UV-vis absorption and steady-state, synchronous and three-dimensional fluorescence techniques. Characteristic effects observed for human hemoglobin intrinsic fluorescence during interaction with uric acid at neutral pH point at the formation of stacking non-covalent and non-fluorescent complexes. All the calculated parameters, the binding, fluorescence quenching and bimolecular quenching rate constants, as well as Förster resonance energy transfer parameters confirm the existence of static quenching. The results of synchronous fluorescence measurements indicate that the fluorescence quenching of human hemoglobin originates both from Trp and Tyr residues and that the addition of uric acid could significantly hinder the physiological functions of human hemoglobin.

  3. Study on the interaction of silver(I) complex with bovine serum albumin by spectroscopic techniques.

    PubMed

    Shahabadi, Nahid; Maghsudi, Maryam; Ahmadipour, Zeinab

    2012-06-15

    The interaction of silver(I) complex, [Ag (2,9-dimethyl-1,10-phenanthroline)(2)](NO(3))·H(2)O, and bovine serum albumin (BSA) was investigated by spectrophotometry, spectrofluorimetry and circular dichroism (CD) techniques. The experimental results indicated that the quenching mechanism of BSA by the complex was a static procedure. Various binding parameters were evaluated. The negative value of ΔH, negative value of ΔS and the negative value of ΔG indicated that van der Waals force and hydrogen bonding play major roles in the binding of the complex and BSA. Based on Forster's theory of non-radiation energy transfer, the binding distance, r, between the donor (BSA) and acceptor (Ag(I) complex) was evaluated. The results of CD and UV-vis spectroscopy showed that the binding of this complex could bind to BSA and be effectively transported and eliminated in the body.

  4. Spectroscopic techniques applied to the characterization of decorated potteries from Caltagirone (Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Barilaro, D.; Barone, G.; Crupi, V.; Donato, M. G.; Majolino, D.; Messina, G.; Ponterio, R.

    2005-06-01

    The aim of the present work is the characterization of decorated pottery samples from Caltagirone (Sicily, Italy), a renowned production centre of this kind of artwork. These fragments were found during archaeological excavations and were attributed to historical periods extremely far in time from each other (from XVIII century b.C. to XVI a.C.). Therefore, we expect that the manufacture techniques result rather different over so long time. The measurements, performed by Fourier Transform-InfraRed (FT-IR) absorbance and micro-Raman scattering, allowed us a non-destructive study of so precious artefacts. Some pigments were identified, various elements of ceramic paste and glazed layer were characterized.

  5. Characterization of ceramic films and interfaces by electron microscopic and spectroscopic techniques

    SciTech Connect

    Erdemir, A.; Cheng, C.C.

    1988-01-01

    In this study, Auger electron spectroscopy (AES) in combination with inert gas ion milling and cross-sectional transmission electron microscopy (XTEM) were employed to investigate the chemical and microstructural characteristics of a TiN film on a M50 steel and the film-substrate interfaces formed during ion plating at 100 C and 500 C deposition temperatures. The results of both analytical techniques indicated that the coating produced at 100 C was composed of a thin Ti layer (approximately 1000 A) and a thick TiN layer. Upon vacuum annealing at 500 C for 45 minutes, it was found that the Ti rich interlayer was transformed into a TiC phase. The coating produced at 500 C consisted of a thin TiC and a relatively thick TiN layers. Ion plating as well as post vacuum annealing at 500 C resulted in grain growth and reduced defect density. 11 refs., 8 figs.

  6. Analysis of the binding interaction in uric acid - Human hemoglobin system by spectroscopic techniques.

    PubMed

    Makarska-Bialokoz, Magdalena

    2017-01-31

    The binding interaction between human hemoglobin and uric acid has been studied for the first time, by UV-vis absorption and steady-state, synchronous and three-dimensional fluorescence techniques. Characteristic effects observed for human hemoglobin intrinsic fluorescence during interaction with uric acid at neutral pH point at the formation of stacking non-covalent and non-fluorescent complexes. All the calculated parameters, the binding, fluorescence quenching and bimolecular quenching rate constants, as well as Förster resonance energy transfer parameters confirm the existence of static quenching. The results of synchronous fluorescence measurements indicate that the fluorescence quenching of human hemoglobin originates both from Trp and Tyr residues and that the addition of uric acid could significantly hinder the physiological functions of human hemoglobin.

  7. Comparison of spectroscopic techniques for the determination of Kjeldahl and ammoniacal nitrogen content of farmyard manure.

    PubMed

    Kemsley, E K; Tapp, H S; Scarlett, A J; Miles, S J; Hammond, R; Wilson, R H

    2001-02-01

    The feasibility of determining the nitrogen content of farmyard manure using infrared spectroscopy was investigated. Fifteen samples each of cattle, pig, and turkey manure were analyzed by three infrared techniques: Fourier transform mid-infrared (MIR), using attenuated total reflection (ATR); near-infrared reflectance (NIR-R); and near-infrared optothermal photoacoustic (NIR-OT). The near-infrared measurements were made at wavelengths determined respectively by four (NIR-OT) and five (NIR-R) band-pass filters. The total nitrogen (using the Kjeldahl method) and volatile (ammoniacal) nitrogen contents of all samples were measured by wet chemistry. Internally cross-validated (ICV) partial least-squares (PLS) regression was then used to obtain calibrations for the nitrogen content. The data sets obtained by each technique were treated separately. Within these sets, data from each manure type were treated both separately and combined: the best predictive ability was obtained by combining data from all three manure types. From the combined data set, the residual standard deviations and correlation coefficients for the ICV-predicted versus actual Kjeldahl nitrogen content were, respectively, 6772 mg/kg dry wt, 0.862 (MIR); 9434 mg/kg dry wt, 0.771 (NIR-OT); and 8943 mg/kg dry wt, 0.865 (NIR-R). For the ammoniacal nitrogen content, the residual standard deviations and correlation coefficients were 3869 mg/kg dry wt, 0.899 (MIR); 6079 mg/kg dry wt, 0.820 (NIR-OT); and 3498 mg/kg dry wt, 0.961 (NIR-R).

  8. Preparation of H2SO4 doped Polyaniline thin film solar cells by spin coating technique

    NASA Astrophysics Data System (ADS)

    Patel, Abhishek; Pataniya, Pratik; Patel, K. D.; Solanki, G. K.; Pathak, V. M.

    2017-05-01

    A water diluted H2SO4 solution was used to dissolve Polyaniline in order to obtain a solution for preparation of thin films by spin coating technique. The chemical bonding characteristics of the prepared films were investigated using Furrier transform infrared spectroscopy (FTIR) and the structural characterizations were accomplished by X-ray diffraction (XRD). UV-VIS absorption spectroscopy was used to determine the optical band gap of the deposited PANi films and the indirect optical band gap of PANi was estimated to be in the range of 1.3 to 1.8 eV from the Tauc's plot. Further, these films were deposited on the n-MoSe2 crystal in order to complete a solar cell structure. The polychromatic photo response of the prepared solar cells for different intensities was studied at room temperature and the efficiency and fill factor were found to be 1% and 0.26 respectively. The obtained Photo-conversion characteristics (I-V) were also used to determined series and shunt resistances of the prepared device. The series resistance was found to be around 33.3 kΩ which is quite high. This may be a reason for such a low efficiency of this cell.

  9. Characterizations of multilayer ZnO thin films deposited by sol-gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Khan, M. I.; Bhatti, K. A.; Qindeel, Rabia; Alonizan, Norah; Althobaiti, Hayat Saeed

    In this work, zinc oxide (ZnO) multilayer thin films are deposited on glass substrate using sol-gel spin coating technique and the effect of these multilayer films on optical, electrical and structural properties are investigated. It is observed that these multilayer films have great impact on the properties of ZnO. X-ray Diffraction (XRD) confirms that ZnO has hexagonal wurtzite structure. Scanning Electron Microscopy (SEM) showed the crack-free films which have uniformly distributed grains structures. Both micro and nano particles of ZnO are present on thin films. Four point probe measured the electrical properties showed the decreasing trend between the average resistivity and the number of layers. The optical absorption spectra measured using UV-Vis. showed the average transmittance in the visible region of all films is 80% which is good for solar spectra. The performance of the multilayer as transparent conducting material is better than the single layer of ZnO. This work provides a low cost, environment friendly and well abandoned material for solar cells applications.

  10. Arterial Spin-Labeling in Routine Clinical Practice, Part 1: Technique and Artifacts

    PubMed Central

    Deibler, A.R.; Pollock, J.M.; Kraft, R.A.; Tan, H.; Burdette, J.H.; Maldjian, J.A.

    2015-01-01

    SUMMARY The routine use of arterial spin-labeling (ASL) in a clinical population has led to the depiction of diverse brain pathologic features. Unique challenges in the acquisition, postprocessing, and analysis of cerebral blood flow (CBF) maps are encountered in such a population, and high-quality ASL CBF maps can be generated consistently with attention to quality control and with the use of a dedicated postprocessing pipeline. Familiarity with commonly encountered artifacts can help avoid pitfalls in the interpretation of CBF maps. The purpose of this review was to describe our experience with a heterogeneous collection of ASL perfusion cases with an emphasis on methodology and common artifacts encountered with the technique. In a period of 1 year, more than 3000 pulsed ASL cases were performed as a component of routine clinical brain MR evaluation at both 1.5 and 3T. These ASL studies were analyzed with respect to overall image quality and patterns of perfusion on final gray-scale DICOM images and color Joint Photographic Experts Group (JPEG) CBF maps, and common artifacts and their impact on final image quality were categorized. PMID:18372417

  11. MOS solar cells with oxides deposited by sol-gel spin-coating techniques

    SciTech Connect

    Huang, Chia-Hong; Chang, Chung-Cheng; Tsai, Jung-Hui

    2013-06-15

    The metal-oxide-semiconductor (MOS) solar cells with sol-gel derived silicon dioxides (SiO{sub 2}) deposited by spin coating are proposed in this study. The sol-gel derived SiO{sub 2} layer is prepared at low temperature of 450 Degree-Sign C. Such processes are simple and low-cost. These techniques are, therefore, useful for largescale and large-amount manufacturing in MOS solar cells. It is observed that the short-circuit current (I{sub sc}) of 2.48 mA, the open-circuit voltage (V{sub os}) of 0.44 V, the fill factor (FF) of 0.46 and the conversion efficiency ({eta}%) of 2.01% were obtained by means of the current-voltage (I-V) measurements under AM 1.5 (100 mW/cm{sup 2}) irradiance at 25 Degree-Sign C in the MOS solar cell with sol-gel derived SiO{sub 2}.

  12. Notes on the p-spin glass studied via Hamilton-Jacobi and smooth-cavity techniques

    NASA Astrophysics Data System (ADS)

    Agliari, Elena; Barra, Adriano; Burioni, Raffaella; Di Biasio, Aldo

    2012-06-01

    In these notes, we continue our investigation of classical toy models of disordered statistical mechanics, through techniques recently developed and tested mainly on the paradigmatic Sherrington-Kirkpatrick spin glass. Here, we consider the p-spin-glass model with Ising spins and interactions drawn from a normal distribution N[0,1]. After a general presentation of its properties (e.g., self-averaging of the free energy, existence of a suitable thermodynamic limit), we study its equilibrium behavior within the Hamilton-Jacobi framework and the smooth cavity approach. Through the former we find both the RS and the 1-RSB expressions for the free-energy, coupled with their self-consistent relations for the overlaps. Through the latter, we recover these results as irreducible expression, and we study the generalization of the overlap polynomial identities suitable for this model; a discussion on their deep connection with the structure of the internal energy and the entropy closes the investigation.

  13. Rapid non-destructive assessment of pork edible quality by using VIS/NIR spectroscopic technique

    NASA Astrophysics Data System (ADS)

    Zhang, Leilei; Peng, Yankun; Dhakal, Sagar; Song, Yulin; Zhao, Juan; Zhao, Songwei

    2013-05-01

    The objectives of this research were to develop a rapid non-destructive method to evaluate the edible quality of chilled pork. A total of 42 samples were packed in seal plastic bags and stored at 4°C for 1 to 21 days. Reflectance spectra were collected from visible/near-infrared spectroscopy system in the range of 400nm to 1100nm. Microbiological, physicochemical and organoleptic characteristics such as the total viable counts (TVC), total volatile basic-nitrogen (TVB-N), pH value and color parameters L* were determined to appraise pork edible quality. Savitzky-Golay (SG) based on five and eleven smoothing points, Multiple Scattering Correlation (MSC) and first derivative pre-processing methods were employed to eliminate the spectra noise. The support vector machines (SVM) and partial least square regression (PLSR) were applied to establish prediction models using the de-noised spectra. A linear correlation was developed between the VIS/NIR spectroscopy and parameters such as TVC, TVB-N, pH and color parameter L* indexes, which could gain prediction results with Rv of 0.931, 0.844, 0.805 and 0.852, respectively. The results demonstrated that VIS/NIR spectroscopy technique combined with SVM possesses a powerful assessment capability. It can provide a potential tool for detecting pork edible quality rapidly and non-destructively.

  14. The Book of Kells: A non-invasive MOLAB investigation by complementary spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Doherty, B.; Daveri, A.; Clementi, C.; Romani, A.; Bioletti, S.; Brunetti, B.; Sgamellotti, A.; Miliani, C.

    2013-11-01

    This paper highlights the efficacy of non-invasive portable spectroscopy for assessing the execution technique and constituent materials in one of the most important medieval manuscripts, the Book of Kells. An aimed campaign of in situ measurements by the MObile LABoratory (MOLAB) has analyzed its elemental composition and vibrational and electronic molecular properties. The ample analytical toolbox has afforded complementary diagnostic information of the pigment palette permitting the characterization of both inorganic and organic materials as pigments and dyes in the white, purple, blue, red, orange, green and black areas. In particular, the novel widespread use of calcinated gypsum (anhydrite) as both a white pigment and in correlation to the organic dyes in this manuscript has been noted. The non-invasive identification of the organic dye orchil is significant considering its rare non invasive detection in medieval manuscripts. Finally the occurrence of particular alterations of the organic black areas giving rise to calcium carboxylate and calcium oxalate has been specifically highlighted. Importantly, this work elaborates complex aspects of the employed painting materials which have given rise to numerous significant points of interest for a more elaborate understanding of this Irish treasure.

  15. In vitro DNA binding studies of anticancer drug idarubicin using spectroscopic techniques.

    PubMed

    Ozluer, Can; Kara, Hayriye Eda Satana

    2014-09-05

    The interaction between idarubicin and double stranded deoxyribonucleic acid (ds-DNA) was investigated by UV-VIS spectrophotometry, fluorescence and Raman spectroscopy techniques. The absorption spectra of idarubicin with ds-DNA showed a slight red shift and hypochromic effect. In the fluorescence experiments, emission peaks were decreased by adding ds-DNA. Using ethidium bromide (ETB) as a fluorescence probe, fluorescence quenching of the emission peak was observed in the ETB-DNA system when idarubicin was added. Moreover, similar results were obtained in Raman spectroscopy. Binding constants of idarubicin with ds-DNA were determined as 5.14×10(5) M(-1) and 5.8×10(5) M(-1) for UV-VIS spectrophotometry and fluorescence spectroscopy, respectively. The large binding constant indicated that idarubicin has a high affinity with ds-DNA. All the evidences indicated that the binding mode of idarubicin with DNA was an intercalative binding. Furthermore, quantitative determination of idarubicin in pharmaceutical formulation was done. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. The Book of Kells: a non-invasive MOLAB investigation by complementary spectroscopic techniques.

    PubMed

    Doherty, B; Daveri, A; Clementi, C; Romani, A; Bioletti, S; Brunetti, B; Sgamellotti, A; Miliani, C

    2013-11-01

    This paper highlights the efficacy of non-invasive portable spectroscopy for assessing the execution technique and constituent materials in one of the most important medieval manuscripts, the Book of Kells. An aimed campaign of in situ measurements by the MObile LABoratory (MOLAB) has analyzed its elemental composition and vibrational and electronic molecular properties. The ample analytical toolbox has afforded complementary diagnostic information of the pigment palette permitting the characterization of both inorganic and organic materials as pigments and dyes in the white, purple, blue, red, orange, green and black areas. In particular, the novel widespread use of calcinated gypsum (anhydrite) as both a white pigment and in correlation to the organic dyes in this manuscript has been noted. The non-invasive identification of the organic dye orchil is significant considering its rare non invasive detection in medieval manuscripts. Finally the occurrence of particular alterations of the organic black areas giving rise to calcium carboxylate and calcium oxalate has been specifically highlighted. Importantly, this work elaborates complex aspects of the employed painting materials which have given rise to numerous significant points of interest for a more elaborate understanding of this Irish treasure. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Classical Raman spectroscopic studies of NADH and NAD+ bound to liver alcohol dehydrogenase by difference techniques

    SciTech Connect

    Chen, D.; Yue, K.T.; Martin, C.; Rhee, K.W.; Sloan, D.; Callender, R.

    1987-07-28

    We report the Raman spectra of reduced and oxidized nicotinamide adenine dinucleotide (NADH and NAD+, respectively) and adenosine 5'-diphosphate ribose (ADPR) when bound to the coenzyme site of liver alcohol dehydrogenase (LADH). The bound NADH spectrum is calculated by taking the classical Raman difference spectrum of the binary complex, LADH/NADH, with that of LADH. We have investigated how the bound NADH spectrum is affected when the ternary complexes with inhibitors are formed with dimethyl sulfoxide (Me2SO) or isobutyramide (IBA), i.e., LADH/NADH/Me2SO or LADH/NADH/IBA. Similarly, the difference spectra of LADH/NAD+/pyrazole or LADH/ADPR with LADH are calculated. The magnitude of these difference spectra is on the order of a few percent of the protein Raman spectrum. We report and discuss the experimental configuration and control procedures we use in reliably calculating such small difference signals. These sensitive difference techniques could be applied to a large number of problems where the classical Raman spectrum of a ''small'' molecule, like adenine, bound to the active site of a protein is of interest. The spectrum of bound ADPR allows an assignment of the bands of the bound NADH and NAD+ spectra to normal coordinates located primarily on either the nicotinamide or the adenine moiety. By comparing the spectra of the bound coenzymes with model compound data and through the use of deuterated compounds, we confirm and characterize how the adenine moiety is involved in coenzyme binding and discuss the validity of the suggestion that the adenine ring is protonated upon binding. The nicotinamide moiety of NADH shows significant molecular changes upon binding.

  18. Classical Raman spectroscopic studies of NADH and NAD+ bound to liver alcohol dehydrogenase by difference techniques.

    PubMed

    Chen, D; Yue, K T; Martin, C; Rhee, K W; Sloan, D; Callender, R

    1987-07-28

    We report the Raman spectra of reduced and oxidized nicotinamide adenine dinucleotide (NADH and NAD+, respectively) and adenosine 5'-diphosphate ribose (ADPR) when bound to the coenzyme site of liver alcohol dehydrogenase (LADH). The bound NADH spectrum is calculated by taking the classical Raman difference spectrum of the binary complex, LADH/NADH, with that of LADH. We have investigated how the bound NADH spectrum is affected when the ternary complexes with inhibitors are formed with dimethyl sulfoxide (Me2SO) or isobutyramide (IBA), i.e., LADH/NADH/Me2SO or LADH/NADH/IBA. Similarly, the difference spectra of LADH/NAD+/pyrazole or LADH/ADPR with LADH are calculated. The magnitude of these difference spectra is on the order of a few percent of the protein Raman spectrum. We report and discuss the experimental configuration and control procedures we use in reliably calculating such small difference signals. These sensitive difference techniques could be applied to a large number of problems where the classical Raman spectrum of a "small" molecule, like adenine, bound to the active site of a protein is of interest. The spectrum of bound ADPR allows an assignment of the bands of the bound NADH and NAD+ spectra to normal coordinates located primarily on either the nicotinamide or the adenine moiety. By comparing the spectra of the bound coenzymes with model compound data and through the use of deuterated compounds, we confirm and characterize how the adenine moiety is involved in coenzyme binding and discuss the validity of the suggestion that the adenine ring is protonated upon binding. The nicotinamide moiety of NADH shows significant molecular changes upon binding.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Surface analysis of all elements with isotopic resolution at high ambient pressures using ion spectroscopic techniques

    SciTech Connect

    Smentkowski, V.S.; Krauss, A.R.; Gruen, D.M.; Holecek, J.C.; Schultz, J.A.

    1997-09-01

    The authors have developed a mass spectrometer capable of surface analysis using the techniques of secondary ion mass spectroscopy (SIMS) and mass spectroscopy of recoiled ions (MSRI). For SIMS, an energetic ion beam creates a collision cascade which results in the ejection of low kinetic energy secondary ions from the surface being analyzed. The low kinetic energy SIMS ions are very susceptible to charge neutralization with the surface, and as a result, the SIMS ion yield varies by orders of magnitude depending on the chemical state of the surface. SIM spectra contain elemental ions, and molecular ions. For MSRI, a pulsed ion beam induces a binary collision with the surface being analyzed and the surface species are recoiled into the forward scattering direction with a large kinetic energy. The violence of the binary collision results in complete molecular decomposition, and only elemental ions are detected. The high kinetic energy MSRI ions are much less susceptible to charge neutralization with the surface than the low kinetic energy SIMS ions. In MSRI, the ion yield typically varies by less than a factor of ten as the chemical state of the surface changes--simplifying quantitative analysis vs. SIMS. In this paper, they authors will demonstrate that the high kinetic energy MSRI ions are able to transverse high pressure paths with only a reduction in peak intensity--making MSRI an ideal tool for real-time, in-situ film growth studies. The use of a single analyzer for both MSRI and SIMS is unique and provides complimentary information.

  20. Measurement of the optical properties of skin using terahertz time-domain spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Wilmink, Gerald J.; Ibey, Bennett L.; Tongue, Thomas; Schulkin, Brian; Peralta, Xomalin; Rivest, Benjamin D.; Haywood, Eric C.; Roach, William P.

    2010-02-01

    Terahertz (THz) radiation is increasingly being used in biomedical imaging and spectroscopy applications. These techniques show tremendous promise to provide new sophisticated tools for the improved detection of skin cancer. However, despite recent efforts to develop these applications, few studies have been conducted to characterize the optical properties of skin at THz frequencies. Such information is required to better understand THz-tissue interactions, and is critical for determining the feasibility of proposed applications. In this study, we have developed and tested a THz time-domain spectroscopy system. We used this system to acquire the optical properties for fresh and frozen/thawed excised porcine skin from 0.1 to 2.0 THz. Results show that the index of refraction (n) for both frozen and fresh skin decreases with frequency. For frozen skin, n equals 2.5 at 0.1 THz and 2.0 at 2.0 THz, and for fresh skin equals 2.0 at 0.1 THz and 1.7 at 2.0 THz. Values for the absorption coefficient (μa) increase with frequency for both frozen and fresh skin. Frozen skin exhibits μa values equal to 56 cm-1 at 0.1 THz and 550 cm-1 at 2.0 THz, whereas fresh skin exhibits values of 56 cm-1 at 0.1 THz and 300 cm-1 at 2.0 THz. Assuming the optical penetration depth (δ) is inversely proportional to μa (absorption-dominated interactions), THz radiation has limited δ in skin (200 μm at 0.1 THz to 40 μm at 2.0 THz). These results suggest that applications exploiting THz radiation show the most promise for investigating superficial tissues.

  1. Development and experimental testing of an optical micro-spectroscopic technique incorporating true line-scan excitation.

    PubMed

    Biener, Gabriel; Stoneman, Michael R; Acbas, Gheorghe; Holz, Jessica D; Orlova, Marianna; Komarova, Liudmila; Kuchin, Sergei; Raicu, Valerică

    2013-12-27

    Multiphoton micro-spectroscopy, employing diffraction optics and electron-multiplying CCD (EMCCD) cameras, is a suitable method for determining protein complex stoichiometry, quaternary structure, and spatial distribution in living cells using Förster resonance energy transfer (FRET) imaging. The method provides highly resolved spectra of molecules or molecular complexes at each image pixel, and it does so on a timescale shorter than that of molecular diffusion, which scrambles the spectral information. Acquisition of an entire spectrally resolved image, however, is slower than that of broad-bandwidth microscopes because it takes longer times to collect the same number of photons at each emission wavelength as in a broad bandwidth. Here, we demonstrate an optical micro-spectroscopic scheme that employs a laser beam shaped into a line to excite in parallel multiple sample voxels. The method presents dramatically increased sensitivity and/or acquisition speed and, at the same time, has excellent spatial and spectral resolution, similar to point-scan configurations. When applied to FRET imaging using an oligomeric FRET construct expressed in living cells and consisting of a FRET acceptor linked to three donors, the technique based on line-shaped excitation provides higher accuracy compared to the point-scan approach, and it reduces artifacts caused by photobleaching and other undesired photophysical effects.

  2. Study on the interaction between histidine-capped Au nanoclusters and bovine serum albumin with spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Zheng, Chengzhi; Wang, Huiping; Xu, Wei; Xu, Chaoyong; Liang, Jiangong; Han, Heyou

    2014-01-01

    The understanding of the protein-nanoclusters interaction has significant implications for biological applications of nanoclusters (NCs). In this manuscript, the interaction of histidine-capped Au nanoclusters (NCs) with bovine serum albumin (BSA) has been investigated by fluorescence, UV-vis, circular dichroism (CD) and Raman spectroscopic techniques under simulative physiological conditions. The results showed that the fluorescence of BSA was quenched by Au NCs. The quenching mechanism was discussed to be a dynamic quenching style, which was proved by the fluorescence spectra and UV-vis absorption spectra. According to modified Stern-Volmer equations at different temperatures, corresponding thermodynamic parameters, ΔHθ, ΔSθ and ΔGθ were observed to be 35.97 kJ mol-1, 199.53 J mol-1 K-1 and -23.49 kJ mol-1, respectively. The hydrophobic force played a key role in the interaction process. Further results from the CD spectra and Raman spectra demonstrated that the α-helical content in BSA was reduced upon interaction with Au NCs which induced a partial protein destabilization. This study contributes to a better understanding of the biology toxicity of Au NCs to biomolecular, which is very essential for the development of safe and functional Au NCs.

  3. Binding of caffeine with caffeic acid and chlorogenic acid using fluorescence quenching, UV/vis and FTIR spectroscopic techniques.

    PubMed

    Belay, Abebe; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2016-03-01

    The interactions of caffeine (CF) with chlorogenic acid (CGA) and caffeic acid (CFA) were investigated by fluorescence quenching, UV/vis and Fourier transform infrared (FTIR) spectroscopic techniques. The results of the study indicated that the fluorescence quenching between caffeine and hydroxycinnamic acids could be rationalized in terms of static quenching or the formation of non-fluorescent CF-CFA and CF-CGA complexes. From fluorescence quenching spectral analysis, the quenching constant (KSV), quenching rate constant (kq), number of binding sites (n), thermodynamic properties and conformational changes of the interaction were determined. The quenching constants (KSV) between CF and CGA, CFA are 1.84 × 10(4) and 1.04 × 10(4) L/mol at 298 K and their binding site n is ~ 1. Thermodynamic parameters determined using the Van't Hoff equation indicated that hydrogen bonds and van der Waal's forces have a major role in the reaction of caffeine with caffeic acid and chlorogenic acid. The 3D fluorescence, UV/vis and FTIR spectra also showed that the binding of CF with CFA and CGA induces conformational changes in CFA and CGA. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Interaction of an antiepileptic drug, lamotrigine with human serum albumin (HSA): Application of spectroscopic techniques and molecular modeling methods.

    PubMed

    Poureshghi, Fatemeh; Ghandforoushan, Parisa; Safarnejad, Azam; Soltani, Somaieh

    2017-01-01

    Lamotrigine (an epileptic drug) interaction with human serum albumin (HSA) was investigated by fluorescence, UV-Vis, FTIR, CD spectroscopic techniques, and molecular modeling methods. Binding constant (Kb) of 5.74×10(3) and number of binding site of 0.97 showed that there is a slight interaction between lamotrigine and HSA. Thermodynamic studies was constructed using the flourimetric titrations in three different temperatures and the resulted data used to calculate the parameters using Vant Hoff equation. Decreased Stern Volmer quenching constant by enhanced temperature revealed the static quenching mechanism. Negative standard enthalpy (ΔH) and standard entropy (ΔS) changes indicated that van der Waals interactions and hydrogen bonds were dominant forces which facilitate the binding of Lamotrigine to HSA, the results were confirmed by molecular docking studies which showed no hydrogen binding. The FRET studies showed that there is a possibility of energy transfer between Trp214 and lamotrigine. Also the binding of lamotrigine to HSA in the studied concentrations was not as much as many other drugs, but the secondary structure of the HSA was significantly changed following the interaction in a way that α-helix percentage was reduced from 67% to 57% after the addition of lamotrigine in the molar ratio of 4:1 to HSA. According to the docking studies, lamotrigine binds to IB site preferably.

  5. Conformers of β-aminoisobutyric acid probed by jet-cooled microwave and matrix isolation infrared spectroscopic techniques.

    PubMed

    Kuş, N; Sharma, A; Peña, I; Bermúdez, M C; Cabezas, C; Alonso, J L; Fausto, R

    2013-04-14

    β-aminoisobutyric acid (BAIBA) has been studied in isolation conditions: in the gas phase and trapped into a cryogenic N2 matrix. A solid sample of the compound was vaporized by laser ablation and investigated through their rotational spectra in a supersonic expansion using two different spectroscopic techniques: broadband chirped pulse Fourier transform microwave spectroscopy and conventional molecular beam Fourier transform microwave spectroscopy. Four conformers with structures of two types could be successfully identified by comparison of the experimental rotational and (14)N nuclear quadruple coupling constants with those predicted theoretically: type A, bearing an OH⋯N intramolecular hydrogen bond and its carboxylic group in the trans geometry (H-O-C=O dihedral ∼180°), and type B, having an NH⋯O bond and the cis arrangement of the carboxylic group. These two types of conformers could also be trapped from the gas phase into a cryogenic N2 matrix and probed by Fourier transform infrared (IR) spectroscopy. In situ irradiation of BAIBA isolated in N2 matrix of type B conformers using near-IR radiation tuned at the frequency of the O-H stretching 1st overtone (∼6930 cm(-1)) of these forms allowed to selectively convert them into type A conformers and into a new type of conformers of higher energy (type D) bearing an NH⋯O=C bond and a O-H "free" trans carboxylic group.

  6. Conformers of β-aminoisobutyric acid probed by jet-cooled microwave and matrix isolation infrared spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Kuş, N.; Sharma, A.; Peña, I.; Bermúdez, M. C.; Cabezas, C.; Alonso, J. L.; Fausto, R.

    2013-04-01

    β-aminoisobutyric acid (BAIBA) has been studied in isolation conditions: in the gas phase and trapped into a cryogenic N2 matrix. A solid sample of the compound was vaporized by laser ablation and investigated through their rotational spectra in a supersonic expansion using two different spectroscopic techniques: broadband chirped pulse Fourier transform microwave spectroscopy and conventional molecular beam Fourier transform microwave spectroscopy. Four conformers with structures of two types could be successfully identified by comparison of the experimental rotational and 14N nuclear quadruple coupling constants with those predicted theoretically: type A, bearing an OH⋯N intramolecular hydrogen bond and its carboxylic group in the trans geometry (H-O-C=O dihedral ˜180°), and type B, having an NH⋯O bond and the cis arrangement of the carboxylic group. These two types of conformers could also be trapped from the gas phase into a cryogenic N2 matrix and probed by Fourier transform infrared (IR) spectroscopy. In situ irradiation of BAIBA isolated in N2 matrix of type B conformers using near-IR radiation tuned at the frequency of the O-H stretching 1st overtone (˜6930 cm-1) of these forms allowed to selectively convert them into type A conformers and into a new type of conformers of higher energy (type D) bearing an NH⋯O=C bond and a O-H "free" trans carboxylic group.

  7. Study on the interaction between bovine serum albumin and CdTe quantum dots with spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Liang, Jiangong; Cheng, Yanping; Han, Heyou

    2008-12-01

    The interaction between bovine serum albumin (BSA) and CdTe quantum dots (QDs) was studied by fluorescence, UV-vis and Raman spectroscopic techniques. The results showed that the fluorescence of BSA was strongly quenched by CdTe QDs. The quenching mechanism was discussed to be a static quenching procedure, which was proved by the quenching rate constant ( Kq) and UV-vis absorption spectra. According to Lineweaver-Burk equations at different temperatures, the thermodynamic parameters, Δ H θ, Δ S θ and Δ G θ were observed to be -23.69 kJ mol -1, 48.39 J mol -1 K -1 and -38.04 kJ mol -1, respectively. The binding constant ( KA) and the number of binding sites ( n) were obtained by Scatchard equation. It was found that hydrophobic force and sulfhydryl group played a key role in the interaction process. Further results from Raman spectra indicated that the α-helical content in BSA reduced after binding with CdTe QDs.

  8. MnO spin-wave dispersion curves from neutron powder diffraction

    SciTech Connect

    Goodwin, Andrew L.; Dove, Martin T.; Tucker, Matthew G.; Keen, David A.

    2007-02-15

    We describe a model-independent approach for the extraction of spin-wave dispersion curves from powder neutron total scattering data. Our approach is based on a statistical analysis of real-space spin configurations to calculate spin-dynamical quantities. The RMCPROFILE implementation of the reverse Monte Carlo refinement process is used to generate a large ensemble of supercell spin configurations from MnO powder diffraction data collected at 100 K. Our analysis of these configurations gives spin-wave dispersion curves for MnO that agree well with those determined independently using neutron triple-axis spectroscopic techniques.

  9. Perfusion MR imaging of enhancing brain tumors: Comparison of arterial spin labeling technique with dynamic susceptibility contrast technique.

    PubMed

    Soni, Neetu; Dhanota, Devender Pal S; Kumar, Sunil; Jaiswal, Awadhesh K; Srivastava, Arun K

    2017-01-01

    Arterial spin labeling (ASL) magnetic resonance (MR) perfusion is a noninvasive and repeatable method for quantitatively measuring cerebral blood flow (CBF). This study aims to compare measurements of ASL-derived CBF with dynamic susceptibility contrast (DSC) MRI in the assessment of enhancing brain tumors (primary and metastatic), with an aim to use ASL as an alternative to DSC. Thirty patients with newly diagnosed brain tumors (16 meningiomas, 6 gliomas, 3 metastases, 2 cerebellopontine angle schwannoma, 1 central neurocytoma, and 2 low-grade gliomas) were examined using a 3T MR scanner. Values of CBF, regional cerebral blood flow (rCBF), and regional cerebral blood volume (rCBV) were determined in the tumor (T) as well as in the contralateral normal gray matter (GM) and white matter (WM). Tumor-to-GM or WM CBF, rCBF, and rCBV ratios were calculated to estimate normalized perfusion values (i.e., ASL normalized tumor blood flow [nTBF], DSC nTBF, and DSC normalized tumor blood volume [nTBV]) from the ASL and DSC techniques. ASL and DSC MRI derived perfusion parameters were compared using paired t-test and correlated using Pearson correlation coefficient. Mean values for ASL nTBF and DSC nTBF using contralateral GM as the reference point were 2.98 ± 1.67and 2.91 ± 1.43, respectively. A very strong correlation coefficient was found between ASL nTBF and DSC nTBF with contralateral GM as the reference region (r = 0.903; R2= 0.813). Mean DSC nTBF and DSC nTBV also showed strong correlation (r = 0.83; R2= 0.701). Our study results suggested that measurement of CBF from ASL possesses the potential for a noninvasive assessment of blood flow in intracranial tumors as an alternate to DSC MRI, in those patients requiring multiple follow-up imaging and in patients with impaired renal functions.

  10. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilde, S.; Zhang, Y.; Dall'Osto, M.

    2014-04-01

    The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterized by a less dense urbanization. We present here the results obtained in San Pietro Capofiume, which is located in a sparsely inhabited sector of the Po Valley, Italy. The experiment was carried out in summer 2009 in the framework of the EUCAARI project ("European Integrated Project on Aerosol, Cloud Climate Aerosol Interaction"). For the first time in Europe, six state-of-the-art techniques were used in parallel: (1) on-line TSI aerosol time-of-flight mass spectrometer (ATOFMS), (2) on-line Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS), (3) soot particle aerosol mass spectrometer (SP-AMS), (4) on-line high resolution time-of-flight mass spectrometer-thermal desorption aerosol gas chromatograph (HR-ToFMS-TAG), (5) off-line twelve-hour resolution proton nuclear magnetic resonance (H-NMR) spectroscopy, and (6) chemical ionization mass spectrometry (CIMS) for the analysis of gas-phase precursors of secondary aerosol. Data from each aerosol spectroscopic method were analysed individually following ad-hoc tools (i.e. PMF for AMS, Art-2a for ATOFMS). The results obtained from each techniques are herein presented and compared. This allows us to clearly link the modifications in aerosol chemical composition to transitions in air mass origin and meteorological regimes. Under stagnant conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC

  11. Stable carbon dioxide isotopes for partitioning grassland fluxes: a comparison of Mass Spectrometric and Spectroscopic (FTIR and QCL) techniques.

    NASA Astrophysics Data System (ADS)

    Zeeman, M. J.; Mohn, J.; Tuzson, B.; Eugster, W.; Werner, R. A.; Emmenegger, L.; Buchmann, N.

    2006-12-01

    Three research sites on elevations covering the relevant stages of the Swiss agricultural system (400, 1000, and 2000 m a.s.l.) have been established. This allows for in-situ investigation of the processes involved in green-house gas exchanges of grassland. A first assessment of stable carbon dioxide isotope analysis has provided valuable information on CO2 flux partitioning. For the first time a comparison of three independent measurement techniques for stable isotope ratios (13C/12C) and (18O/16O) and green-house gas concentrations of carbon dioxide, methane and nitrous oxide was performed. During a three week period, air samples were collected at four height profiles (z = 0.055; 0.14; 0.40; 1.90 m) and in a regular two hours interval by automated air samplers connected to a switching inlet system. The isotopic ratios (13C/12C) and (18O/16O) of carbon dioxide were measured in the laboratory with Isotope Ratio Mass Spectrometry (IRMS). Simultaneously, two additional optical techniques were used to continuously measure these stable isotope ratios in the field: (1) Fourier Transform Infrared (FTIR) and (2) Quantum Cascade Laser (QCL) spectroscopy. The time resolution was one minute and one second, respectively. Furthermore, the greenhouse gas concentrations were continuously monitored with an open path IR gas analyser for carbon dioxide and a photo-acoustic gas analyser for carbon dioxide, methane, and nitrous oxide. The FTIR spectrometer also measured the concentrations of carbon dioxide, carbon monoxide, methane and nitrous oxide. The preliminary results show the added value of high time resolution measurements for the investigation of flux partitioning, with use of new spectroscopic technologies. The FTIR instrument achieved accuracy in δ13C ratios of +/- 0.4 %0. The achieved temporal resolution of 1 second of the QCL system has significant potential in computation of eddy covariance isotopic fluxes.

  12. Maneuver reconstruction techniques for open-loop spin-stabilized spacecraft

    NASA Technical Reports Server (NTRS)

    Frauenholz, R. B.

    1980-01-01

    The Pioneer missions were supported by spin-stabilized spacecraft designs using open-loop control and blow-down propulsion subsystems. Reliable estimates of the ever-changing performance inherent to these subsystems were needed to effectively design and reconstruct trajectory correction maneuver (TCM) strategies. These performance updates were obtained by adjusting model parameters to match independent telemetric and radiometric observations to define the simultaneous changes in attitude, velocity, and spin rate during a maneuver sequence.

  13. Study of anisotropy of spin cast and vapor deposited polyimide films using internal reflection techniques

    SciTech Connect

    Liberman, V.

    1996-11-01

    We have compared anisotropy of spin cast and vapor deposited polyimide (VDP) films, using internal reflection infrared spectroscopy. The films were deposited directly on the internal reflection element. We find that spin cast films are more anisotropic than their VDP counterparts, with the polyimide chains tending to align parallel to the substrate. Both films are found to contain more and less ordered regions. Within the ordered regions, the plane of the phenyl ring tends to align parallel to the substrate.

  14. A comparison investigation of DNP-binding effects to HSA and HTF by spectroscopic and molecular modeling techniques.

    PubMed

    Zolfagharzadeh, Mahboobeh; Pirouzi, Maliheh; Asoodeh, Ahmad; Saberi, Mohammad Reza; Chamani, Jamshidkhan

    2014-12-01

    This paper describes the interaction between 2,4-dinitrophenol (DNP) with the two drug carrier proteins - human serum albumin (HSA) and human holo transferrin (HTF). Hence, binding characteristics of DNP to HSA and HTF were analyzed by spectroscopic and molecular modeling techniques. Based on results obtained from fluorescence spectroscopy, DNP had a strong ability to quench the intrinsic fluorescence of HSA and HTF through a static quenching procedure. The binding constant and the number of binding sites were calculated as 2.3 × 10(11) M(-1) and .98 for HSA, and 1.7 × 10(11) M(-1) and 1.06 for HTF, respectively. In addition, synchronous fluorescence results showed that the microenvironment of Trp had a slight tendency of increasing its hydrophobicity, whereas the microenvironment of the Tyr residues of HSA did not change and that of HTF showed a significant trend (red shift of about 4 nm) of an increase in polarity. The distance between donor and acceptor was obtained by the Förster energy according to fluorescence resonance energy transfer, and was found to be 3.99 and 3.72 nm for HSA and HTF, respectively. The critical induced aggregation concentration (CCIAC) of the drug on both proteins was determined and confirmed by an inflection point of the zeta potential behavior. Circular dichroism data revealed that the presence of DNP caused a decrease of the α-helical content of HSA and HTF, and induced a remarkable mild denaturation of both proteins. The molecular modeling data confirmed our experimental results. This study is deemed useful for determining drug dosage.

  15. Application of phosphorus-31 and aluminum-27 NMR spectroscopic techniques to study aqueous and methanolic solutions of tetraphenylammonium aluminophosphate

    NASA Astrophysics Data System (ADS)

    Goudarzi, Nasser; Amin, Amir H.

    2017-01-01

    In this work, aluminum-27 and phosphorus-31 NMR spectroscopic techniques were used to investigate and characterize the distribution of aluminophosphate (AlPO) species soluble in the aqueous and methanolic solutions of tetraphenylammonium (TPhA) chloride. The reaction between hexaaquaaluminum cations, [A1(H2O)6]3+, and different phosphate ligands such as H3PO4, H2PO4-, and the acidic dimers H6P2O8 and H5P2O8- resulted in the formation of the soluble AlPO cations. The effective aluminum-27 and phosphorous-31 NMR spectroscopies can be employed to characterize the species present in a solution. Assignment of the peaks present in the aluminum-27 NMR spectra to the aluminate species or aluminate connectivities was done to acquire information about different AlPO complexes. Some resonance lines were observed in the phosphorus-31 {1H} NMR spectra, indicating the existence of different complexes in the AlPO solutions. Some peaks were observed in the methanolic solutions of AlPO at the chemical shifts of -0.41, -6.4, -7.5, -7.9, -13.1, -13.9, -16.6, -18.1, and -20.6 ppm. Four additional peaks were also observed in the phosphorus-31 {1H} NMR spectra of the methanolic solutions of AlPO, whose intensities changed with changes in the methanol:water volume ratio; they were observed in methanol but not in aqueous AlPO.

  16. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilge, S.; Zhang, Y.; Dall'Osto, M.

    2014-11-01

    The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer - HR-ToF-AMS and soot particle aerosol mass spectrometer - SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in

  17. Spectroscopic properties of Fe 2+ ions at tetragonal sites—Crystal field effects and microscopic modeling of spin Hamiltonian parameters for Fe 2+ ( S=2) ions in K 2FeF 4 and K 2ZnF 4

    NASA Astrophysics Data System (ADS)

    Rudowicz, C.; Piwowarska, D.

    2011-11-01

    Magnetic and spectroscopic properties of the planar antiferromagnet K 2FeF 4 are determined by the Fe 2+ ions at tetragonal sites. The two-dimensional easy-plane anisotropy exhibited by K 2FeF 4 is due to the zero field splitting (ZFS) terms arising from the orbital singlet ground state of Fe 2+ ions with the spin S=2. To provide insight into the single-ion magnetic anisotropy of K 2FeF 4, the crystal field theory and the microscopic spin Hamiltonian (MSH) approach based on the tensor method is adopted. Survey of available experimental data on the crystal field energy levels and free-ion parameters for Fe 2+ ions in K 2FeF 4 and related compounds is carried out to provide input for microscopic modeling of the ZFS parameters and the Zeeman electronic ones. The ZFS parameters are expressed in the extended Stevens notation and include contributions up to the fourth-order using as perturbation the spin-orbit and electronic spin-spin couplings within the tetragonal crystal field states of the ground 5D multiplet. Modeling of the ZFS parameters and the Zeeman electronic ones is carried out. Variation of these parameters is studied taking into account reasonable ranges of the microscopic ones, i.e. the spin-orbit and spin-spin coupling constants, and the energy level splittings, suitable for Fe 2+ ions in K 2FeF 4 and Fe 2+:K 2ZnF 4. Conversions between the ZFS parameters in the extended Stevens notation and the conventional ones are considered to enable comparison with the data of others. Comparative analysis of the MSH formulas derived earlier and our more complete ones indicates the importance of terms omitted earlier as well as the fourth-order ZFS parameters and the spin-spin coupling related contributions. The results may be useful also for Fe 2+ ions at axial symmetry sites in related systems, i.e. Fe:K 2MnF 4, Rb 2Co 1-xFe xF 4, Fe 2+:Rb 2CrCl 4, and Fe 2+:Rb 2ZnCl 4.

  18. Spectroscopic data, spin-orbit functions, and revised analysis of strong perturbative interactions for the A {sup 1{Sigma}+} and b {sup 3{Pi}} states of RbCs

    SciTech Connect

    Docenko, O.; Tamanis, M.; Ferber, R.; Bergeman, T.; Kotochigova, S.; Stolyarov, A. V.

    2010-04-15

    The current interest in producing ultracold RbCs molecules by optical excitation from weakly bound Feshbach resonances and stimulated decay to the absolute ground state requires detailed analyses of the intermediate excited states. In this study, we present two sets of experimental Fourier-transform spectroscopic data of the A {sup 1{Sigma}+}-b {sup 3{Pi}} complex. The A-b mixed vibrational levels are the most likely candidates to be intermediates in the molecular formation. The more recent and more accurate data set is from mixed A-b{yields}X transitions, while the second is derived in large part from (4) {sup 1{Sigma}+{yields}}A-b emission and extends to higher A-b energy levels. From a detailed analysis of the spectroscopic data we obtain term values which allow one to construct potentials and spin-orbit functions. Vibrational numbering of the A state has been raised by one quantum over a previous report [T. Bergeman et al., Phys. Rev. A 67, 050501 (2003)] while the numbering of the b state is established with a considerable degree of certainty with help of data on the {sup 85}Rb{sup 133}Cs and {sup 87}Rb{sup 133}Cs isotopomers. In addition, we have performed calculations of spin-orbit functions by two distinct methods. The fitted spin-orbit coupling matrix element between the two {Omega}{sup p}=0{sup +} states, A {sup 1{Sigma}+} and b {sup 3{Pi}}{sub 0+}, happens to agree rather well with the results from both of these methods, while for the diagonal b {sup 3{Pi}} state spin-orbit function, the fitted function agrees fairly well with that obtained by the other method.

  19. a New Hybrid Heuristic Technique for Unit Commitment Considering Spinning Reserve Probability

    NASA Astrophysics Data System (ADS)

    Abdollahi, A.; Ehsan, M.; Rashidinejad, M.; Purakbari-Kasmaie, M.

    2009-08-01

    This paper proposes a new approach for solving generation scheduling and ramp rate constrained unit commitment with considering spinning reserve probability. In order to simulate the probability of reserve in the formulation, the estimated probability that spinning reserve is called and generated has been considered. A hybrid heuristic method between genetic algorithm and lambdad iteration method is applied to solve the problem. The proposed approach is applied to two different cases such as a 10-unit base problem without considering probability of reserve and 10-unit problem with considering probability of reserve. The results are compared with other approaches results to exhibit the superiority of the proposed approach.

  20. Solute-solvated cyclodextrin-bonded phase interactions as studied by the spin probe technique

    SciTech Connect

    Hooper, A.J.; Heindl, J.; Wright, P.; Eastman, M.P.; Kooser, R.G.

    1992-06-25

    Using spin probes with {alpha} and {beta} cyclodextrins, the spin probe-{alpha} cyclodextrin surface interaction is due to polar/nonpolar interactions, but the {beta} cyclodextrin interaction has a bimodal behavior depending upon the solute polarity. For nonpolar probes there is partial insertion into the cyclodextrin cavity, but polar probes involve interactions between the solute and the hydroxyl region surrounding the rims of the bound cyclodextrin. This evidence show that surface immobilized cyclodextrins do not interact in the same way as free cyclodextrins. 66 refs., 2 figs., 8 tabs.

  1. Nondestructive and rapid concurrent estimation of paracetamol and nimesulide in their combined dosage form using Raman spectroscopic technique.

    PubMed

    Lakhwani, Gargi R; Sherikar, O D; Mehta, Priti J

    2013-03-01

    A rapid, nondestructive Raman spectroscopic method was developed for quantitative estimation of paracetamol and nimesulide in their combined dosage form. A Raman univariate calibration model was developed by measuring the peak intensities of paracetamol and nimesulide at 853 cm(-1) and 1336 cm(-1), respectively. The developed method was successfully applied for in situ, concurrent estimation of paracetamol and nimesulide in their combined dosage and method was also validated according to International Conference on Harmonisation guidelines. Thus, the developed Raman spectroscopic method can be applied for simultaneous estimation of paracetamol and nimesulide in their combined dosage form as a process analytical technology tool by pharmaceutical industries for routine quality control.

  2. Application of a new non-linear least squares velocity curve analysis technique for spectroscopic binary stars

    NASA Astrophysics Data System (ADS)

    Karami, K.; Mohebi, R.; Soltanzadeh, M. M.

    2008-11-01

    Using measured radial velocity data of nine double lined spectroscopic binary systems NSV 223, AB And, V2082 Cyg, HS Her, V918 Her, BV Dra, BW Dra, V2357 Oph, and YZ Cas, we find corresponding orbital and spectroscopic elements via the method introduced by Karami and Mohebi (Chin. J. Astron. Astrophys. 7:558, 2007a) and Karami and Teimoorinia (Astrophys. Space Sci. 311:435, 2007). Our numerical results are in good agreement with those obtained by others using more traditional methods.

  3. Dipolar effects on the critical fluctuations in Fe: Investigation by the neutron spin-echo technique MIEZE

    NASA Astrophysics Data System (ADS)

    Kindervater, J.; Säubert, S.; Böni, P.

    2017-01-01

    Iron is one of the archetypical ferromagnets to study the critical fluctuations at a continuous phase transition thus serving as a model system for the application of scaling theory. We report a comprehensive study of the critical dynamics at the transition from the ferro- to the paramagnetic phase in Fe, employing the high-resolution neutron spin-echo technique, modulated intensity of zero effort (MIEZE). The results show that the dipolar interactions lead to an additional damping of the critical spin fluctuations at small momentum transfers q . The results agree essentially with scaling theory if the dipolar interactions are taken into account by means of the mode-coupling equations. However, in contrast to expectations, the dipolar wave number qD that plays a central role in the scaling function f (κ /q ,qD/κ ) becomes temperature dependent. In the limit of small q the critical exponent z crosses over from 2.5 to 2.0.

  4. Spin wave study and optical properties in Fe-doped ZnO thin films prepared by spray pyrolysis technique

    NASA Astrophysics Data System (ADS)

    Lmai, F.; Moubah, R.; El Amiri, A.; Abid, Y.; Soumahoro, I.; Hassanain, N.; Colis, S.; Schmerber, G.; Dinia, A.; Lassri, H.

    2016-07-01

    We investigate the magnetic and optical properties of Zn1-xFexO (x = 0, 0.03, 0.05, and 0.07) thin films grown by spray pyrolysis technique. The magnetization as a function of temperature [M (T)] shows a prevailing paramagnetic contribution at low temperature. By using spin wave theory, we separate the M (T) curve in two contributions: one showing intrinsic ferromagnetism and one showing a purely paramagnetic behavior. Furthermore, it is shown that the spin wave theory is consistent with ab-initio calculations only when oxygen vacancies are considered, highlighting the key role played by structural defects in the mechanism driving the observed ferromagnetism. Using UV-visible measurements, the transmittance, reflectance, band gap energy, band tail, dielectric coefficient, refractive index, and optical conductivity were extracted and related to the variation of the Fe content.

  5. Study of Low Energy Electron Inelastic Scattering Mechanisms Using Spin Sensitive Techniques

    NASA Astrophysics Data System (ADS)

    Hsu, Hongbing

    1995-01-01

    Spin sensitive electron spectroscopies were used to study low energy electron inelastic scattering from metal surfaces and thin films. In these experiments, a beam of spin polarized electrons from a GaAs source is directed on the sample surface, and the spin polarization and intensity are measured as a function of energy loss and scattering angle by a Mott electron polarimeter coupled with a concentric hemispherical energy analyzer. Systematic studies of the angular dependence of inelastically scattered electrons were conducted on a Cu(100) surface, and Mo/Cu(100), non-magnetized Fe/Cu(100), and Co/Cu(100) films. The polarization and intensity of scattered electrons were measured as function of energy loss and scattering angle. Further studies were also conducted on Ag(100) surface and amorphous Cu/Ag(100) films. From the experimental results, the angular distributions of dipole and impact scattered electrons can be determined individually and both are found to peak in the specular scattering direction. Preliminary studies were conducted on magnetized Co/Cu(100) films. The spin dependent scattering intensity asymmetry was measured, with a clearly observable peak at energy loss of ~1 eV, which coincides with the band splitting. The polarizations of secondary electrons produced by an unpolarized primary beam were also measured. The polarizations can be related to the band polarization of magnetized cobalt films.

  6. New Techniques to Test Spin-Gravity Coupling with Atomic Clock

    NASA Technical Reports Server (NTRS)

    Maleki, L.

    2000-01-01

    Recent advances in laser technology have produced the opportunity to realize more stable and accurate atomic clocks, by laser excitation, manipulation and cooling of atoms. In this paper we will describe a new scheme based on the use of lasers with atomic clocks to increase the sensitivity of experimental search for a spin-gravity coupling.

  7. Spectroscopic analysis of solar and cosmic X-ray spectra. 1: The nature of cosmic X-ray spectra and proposed analytical techniques

    NASA Technical Reports Server (NTRS)

    Walker, A. B. C., Jr.

    1975-01-01

    Techniques for the study of the solar corona are reviewed as an introduction to a discussion of modifications required for the study of cosmic sources. Spectroscopic analysis of individual sources and the interstellar medium is considered. The latter was studied via analysis of its effect on the spectra of selected individual sources. The effects of various characteristics of the ISM, including the presence of grains, molecules, and ionization, are first discussed, and the development of ISM models is described. The expected spectral structure of individual cosmic sources is then reviewed with emphasis on supernovae remnants and binary X-ray sources. The observational and analytical requirements imposed by the characteristics of these sources are identified, and prospects for the analysis of abundances and the study of physical parameters within them are assessed. Prospects for the spectroscopic study of other classes of X-ray sources are also discussed.

  8. Use of epr spin-trapping techniques to detect radicals from rat lung lavage fluid following sulfur mustard vapor exposure

    SciTech Connect

    Anderson, D.R.; Yourick, J.J.; Arroyo, C.M.; Young, G.D.; Harris, L.W.

    1993-05-13

    Although well known for skin vesicating properties, pulmonary damage and associated infections account for most of the mortality associated with sulfur mustard (HD). We have employed an in vivo HD vapor exposure model, bronchoalveolar lavage and histopathology in conjunction with electron paramagnetic resonance (EPR) techniques to provide evidence for HD-induced (free radical/lipid peroxidation associated) lung injury. Anesthetized rats were intratracheally intubated and exposed to 0.35 mg HD vapor over 50 min. Immediately, 1 hr or 24 hr after exposure, lungs were lavaged with the spin trap, alpha-phenyl-t-butyl nitrone (PBN; 0.35 mg/ml). Recovered lavage fluid was assayed by EPR spectroscopy for radical spin adducts. Airway lipid extracts were assayed for thiobarbituric acid reactive products (TBARs); while separate groups of rats were used to evaluate histopathology. EPR results show the presence of an ascorbyl radical at 1 and 24 hr, and a carbon centered PBN spin adduct at 24 hr, both indicative of lipid peroxidation. TBAR (A532nm) formation was also detected at 24 hr. Histopathology revealed multifocal separation of the bronchial epithelium from the submucosa with little or no alveolar involvement at 24 hrs. These studies provide evidence that HD may affect lungs by a free radical mechanism which produces membrane and other tissue damage.

  9. Study of coal tar pitch microstructure by using spin probe technique

    SciTech Connect

    Shklyaev, A.A.; Ugay, M.Y.

    1994-12-31

    One of the copper porphyrin complexes has been adopted as a spin probe in order to provide insight into the nature of paramagnetic species of coal tar pitch. It was found that there are three kinds of nonequivalent radical centers displaying a different sensitivity to the spin probes. The majority of radical centers in original coal tar pitch cannot be detected in E.S.R. spectra due to considerable broadening of its lines. These invisible centers give rise to sudden broadening of E.S.R. signals of complex dissolved in the pitch heated over 400 C. The questions regarding the nature of radical states and the reason of abrupt high temperature broadening of pitch signals are discussed.

  10. The use of simulation in the EPR spin probe technique for detection of irradiated seeds.

    PubMed

    Sünnetçioğlu, M M; Dadaylı, D

    2000-10-02

    An electron paramagnetic resonance (EPR) spin probe study of irradiated wheat seeds was performed depending on irradiation dose. The structural changes in the membrane integrity were followed using aqueous solutions of 4-hydroxy-TEMPO (TANOL) spin probe and a line broadening material. In the studies dry seed embryos were kept in these solutions for 150 min. The spectra were recorded at various times of air drying process. The simulation of these spectra indicated a decrease in the water content of the embryos depending on the increasing irradiation dose. This indicates the increase in the permeability of the membranes as a result of the radiation damage. From the decay curves it is possible to determine about irradiation dose, however, this approach is not very successful at close irradiation doses.

  11. X-ray absorption spectroscopic investigation of the spin-transition character in a series of single-site perturbed iron(II) complexes.

    PubMed

    Rudd, Deanne Jackson; Goldsmith, Christian R; Cole, Adam P; Stack, T Daniel P; Hodgson, Keith O; Hedman, Britt

    2005-03-07

    Select ferrous spin-transition complexes with the pentadentate ligand 2,6-bis(bis(2-pyridyl)methoxymethane)pyridine (PY5) were examined using variable-temperature solution solid-state magnetic susceptibility, crystallography, X-ray absorption spectroscopy (XAS), and UV/vis absorption spectroscopy. Altering the single exogeneous ligand, X, of [Fe(PY5)(X)]n)+ is sufficient to change the spin-state of the complexes. When X is the weak-field ligand Cl-, the resultant Fe complex is high-spin from 4 to 300 K, whereas the stronger-field ligand MeCN generates a low-spin complex over this temperature range. With intermediate-strength exogenous ligands (X = N3-, MeOH), the complexes undergo a spin-transition. [Fe(PY5)(N3)]+, as a crystalline solid, transitions gradually from a high-spin to a low-spin complex as the temperature is decreased, as evidenced by X-ray crystallography and solid-state magnetic susceptibility measurements. The spin-transition is also evident from changes in the pre-edge and EXAFS regions of the XAS Fe K-edge spectra on a ground crystalline sample. The spin-transition observed with [Fe(PY5)(MeOH)]2+ appears abrupt by solid-state magnetic susceptibility measurements, but gradual by XAS analysis, differences attributed to sample preparation. This research highlights the strengths of XAS in determining the electronic and geometric structure of such spin-transition complexes and underscores the importance of identical sample preparation in the investigation of these physical properties.

  12. The fusion of MIR absorbance and NIR Raman spectroscopic techniques for identification of improvised explosive materials in multiple scenarios

    NASA Astrophysics Data System (ADS)

    Stokes, Robert J.; Normand, Erwan L.; Lindley, Ruth; Black, Paul; McCulloch, Michael; Middleton, David N.; Smith, W. Ewen; Foulger, Brian; Lewis, Colin

    2009-09-01

    We demonstrate how molecular spectroscopy methods using NIR and MIR lasers can provide rapid detection and identification of many threat materials. It is increasingly recognised that one spectroscopic method will not be suited to every target in every scenario, both in terms of spectroscopic selectivity and the context e.g. vapour phase or within a sealed container. The orthogonal selection rules and capabilities of IR and Raman in combination allow the identification of a very broad range of targets, both in liquid and vapour phase. Therefore, we introduce the benefits of the combining infra-red absorbance based on Quantum Cascade lasers (QC-IR) and NIR Raman spectroscopy for nitrogenous and peroxide based materials. Rapid scan rates up to 10Hz for QC-IR and Raman and are demonstrated using current technology. However, understanding of the chemistry and spectroscopic signatures behind such materials is necessary for accurate fast fitting algorithms to benefit of the full advantage with advances in hardware. This is especially true as future users requirements move towards rapid multiplexed analysis and data fusion from a variety of sensors.

  13. Using non-invasive molecular spectroscopic techniques to detect unique aspects of protein Amide functional groups and chemical properties of modeled forage from different sourced-origins

    NASA Astrophysics Data System (ADS)

    Ji, Cuiying; Zhang, Xuewei; Yu, Peiqiang

    2016-03-01

    The non-invasive molecular spectroscopic technique-FT/IR is capable to detect the molecular structure spectral features that are associated with biological, nutritional and biodegradation functions. However, to date, few researches have been conducted to use these non-invasive molecular spectroscopic techniques to study forage internal protein structures associated with biodegradation and biological functions. The objectives of this study were to detect unique aspects and association of protein Amide functional groups in terms of protein Amide I and II spectral profiles and chemical properties in the alfalfa forage (Medicago sativa L.) from different sourced-origins. In this study, alfalfa hay with two different origins was used as modeled forage for molecular structure and chemical property study. In each forage origin, five to seven sources were analyzed. The molecular spectral profiles were determined using FT/IR non-invasive molecular spectroscopy. The parameters of protein spectral profiles included functional groups of Amide I, Amide II and Amide I to II ratio. The results show that the modeled forage Amide I and Amide II were centered at 1653 cm- 1 and 1545 cm- 1, respectively. The Amide I spectral height and area intensities were from 0.02 to 0.03 and 2.67 to 3.36 AI, respectively. The Amide II spectral height and area intensities were from 0.01 to 0.02 and 0.71 to 0.93 AI, respectively. The Amide I to II spectral peak height and area ratios were from 1.86 to 1.88 and 3.68 to 3.79, respectively. Our results show that the non-invasive molecular spectroscopic techniques are capable to detect forage internal protein structure features which are associated with forage chemical properties.

  14. Using non-invasive molecular spectroscopic techniques to detect unique aspects of protein Amide functional groups and chemical properties of modeled forage from different sourced-origins.

    PubMed

    Ji, Cuiying; Zhang, Xuewei; Yu, Peiqiang

    2016-03-05

    The non-invasive molecular spectroscopic technique-FT/IR is capable to detect the molecular structure spectral features that are associated with biological, nutritional and biodegradation functions. However, to date, few researches have been conducted to use these non-invasive molecular spectroscopic techniques to study forage internal protein structures associated with biodegradation and biological functions. The objectives of this study were to detect unique aspects and association of protein Amide functional groups in terms of protein Amide I and II spectral profiles and chemical properties in the alfalfa forage (Medicago sativa L.) from different sourced-origins. In this study, alfalfa hay with two different origins was used as modeled forage for molecular structure and chemical property study. In each forage origin, five to seven sources were analyzed. The molecular spectral profiles were determined using FT/IR non-invasive molecular spectroscopy. The parameters of protein spectral profiles included functional groups of Amide I, Amide II and Amide I to II ratio. The results show that the modeled forage Amide I and Amide II were centered at 1653 cm(-1) and 1545 cm(-1), respectively. The Amide I spectral height and area intensities were from 0.02 to 0.03 and 2.67 to 3.36 AI, respectively. The Amide II spectral height and area intensities were from 0.01 to 0.02 and 0.71 to 0.93 AI, respectively. The Amide I to II spectral peak height and area ratios were from 1.86 to 1.88 and 3.68 to 3.79, respectively. Our results show that the non-invasive molecular spectroscopic techniques are capable to detect forage internal protein structure features which are associated with forage chemical properties.

  15. Vibronic Characteristics and Spin-Density Distributions in Bacteriochlorins as Revealed by Spectroscopic Studies of 16 Isotopologues. Implications for Energy- and Electron-Transfer in Natural Photosynthesis and Artificial Solar-Energy Conversion.

    PubMed

    Diers, James R; Tang, Qun; Hondros, Christopher J; Chen, Chih-Yuan; Holten, Dewey; Lindsey, Jonathan S; Bocian, David F

    2014-06-26

    Vibronic characteristics and spin-density distributions in the core bacteriochlorin macrocycle were revealed by spectroscopic and theoretical studies of 16 isotopologues. The vibrational modes in copper bacteriochlorin isotopologues were examined via resonance Raman and Fourier-transform infrared spectroscopy. The resonance Raman spectra exhibit an exceptional sparcity of vibronically active modes of the core macrocycle, in contrast with the rich spectra of the natural bacteriochlorophylls. The Qy-excitation resonance Raman spectrum is dominated by a single mode at 727 cm(-1), which calculations suggest is due to a symmetrical accordion-like deformation of the five-atom Cm(CaNCa)pyrroleCm portion of the ring core. This deformation also dominates the vibronic features in the absorption and fluorescence spectra. The spin-density distributions in the π-cation radical of the zinc bacteriochlorin isotopologues were studied by electron paramagnetic resonance spectroscopy. The spectra indicate a significant electron/spin density (ρ ∼ 0.1) on each meso-carbon atom. This observation contradicts the predictions of early calculations that have been assumed to be correct for nearly four decades. Collectively, these findings have implications for how the structural features that characterize natural bacteriochlorophylls might influence energy- and electron-transfer processes in photosynthesis and alter the thinking on the design of synthetic, bacteriochlorin-based arrays for solar-energy conversion.

  16. Note: Electrical detection and quantification of spin rectification effect enabled by shorted microstrip transmission line technique

    SciTech Connect

    Soh, Wee Tee; Ong, C. K.; Peng, Bin; Chai, Guozhi

    2014-02-15

    We describe a shorted microstrip method for the sensitive quantification of Spin Rectification Effect (SRE). SRE for a Permalloy (Ni{sub 80}Fe{sub 20}) thin film strip sputtered onto SiO{sub 2} substrate is demonstrated. Our method obviates the need for simultaneous lithographic patterning of the sample and transmission line, therefore greatly simplifying the SRE measurement process. Such a shorted microstrip method can allow different contributions to SRE (anisotropic magnetoresistance, Hall effect, and anomalous Hall effect) to be simultaneously determined. Furthermore, SRE signals from unpatterned 50 nm thick Permalloy films of area dimensions 5 mm × 10 mm can even be detected.

  17. Note: electrical detection and quantification of Spin Rectification Effect enabled by shorted microstrip transmission line technique.

    PubMed

    Soh, Wee Tee; Peng, Bin; Chai, Guozhi; Ong, C K

    2014-02-01

    We describe a shorted microstrip method for the sensitive quantification of Spin Rectification Effect (SRE). SRE for a Permalloy (Ni80Fe20) thin film strip sputtered onto SiO2 substrate is demonstrated. Our method obviates the need for simultaneous lithographic patterning of the sample and transmission line, therefore greatly simplifying the SRE measurement process. Such a shorted microstrip method can allow different contributions to SRE (anisotropic magnetoresistance, Hall effect, and anomalous Hall effect) to be simultaneously determined. Furthermore, SRE signals from unpatterned 50 nm thick Permalloy films of area dimensions 5 mm × 10 mm can even be detected.

  18. Analysis of hysteretic spin transition and size effect in 3D spin crossover compounds investigated by Monte Carlo Entropic sampling technique in the framework of the Ising-type model

    NASA Astrophysics Data System (ADS)

    Chiruta, D.; Linares, J.; Dahoo, P. R.; Dimian, M.

    2015-02-01

    In spin crossover (SCO) systems, the shape of the hysteresis curves are closely related to the interactions between the molecules, which these play an important role in the response of the system to an external parameter. The effects of short-range interactions on the different shape of the spin transition phenomena were investigated. In this contribution we solve the corresponding Hamiltonian for a three-dimensional SCO system taking into account short-range and long-range interaction using a biased Monte Carlo entropic sampling technique and a semi-analytical method. We discuss the competition between the two interactions which governs the low spin (LS) - high spin (HS) process for a three-dimensional network and the cooperative effects. We demonstrate a strong correlation between the shape of the transition and the strength of short-range interaction between molecules and we identified the role of the size for SCO systems.

  19. The origin, composition and history of cometary ices from spectroscopic studies

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1989-01-01

    The spectroscopic analysis of pristine cometary material provides a very important probe of the chemical identity of the material as well as of the physical and chemical conditions which prevailed during the comet's history. Concerning classical spectroscopy, the spectral regions which will most likely prove most useful are the infrared, the visible and ultraviolet. Newer spectroscopic techniques which have the potential to provide equally important information include nuclear magnetic resonance (NMR) and electron spin resonance (ESR). Each technique is summarized with emphasis placed on the kind of information which can be obtained.

  20. Development of a 3He nuclear spin flip system on an in-situ SEOP 3He spin filter and demonstration for a neutron reflectometer and magnetic imaging technique

    NASA Astrophysics Data System (ADS)

    Hayashida, H.; Oku, T.; Kira, H.; Sakai, K.; Hiroi, K.; Ino, T.; Shinohara, T.; Imagawa, T.; Ohkawara, M.; Ohoyama, K.; Kakurai, K.; Takeda, M.; Yamazaki, D.; Oikawa, K.; Harada, M.; Miyata, N.; Akutsu, K.; Mizusawa, M.; Parker, J. D.; Matsumoto, Y.; Zhang, S.; Suzuki, J.; Soyama, K.; Aizawa, K.; Arai, M.

    2016-04-01

    We have been developing a 3He neutron spin filter (NSF) using the spin exchange optical pumping (SEOP) technique. The 3He NSF provides a high-energy polarized neutron beam with large beam size. Moreover the 3He NSF can work as a π-flipper for a polarized neutron beam by flipping the 3He nuclear spin using a nuclear magnetic resonance (NMR) technique. For NMR with the in-situ SEOP technique, the polarization of the laser must be reversed simultaneously because a non-reversed laser reduces the polarization of the spin-flipped 3He. To change the polarity of the laser, a half-wavelength plate was installed. The rotation angle of the half-wavelength plate was optimized, and a polarization of 97% was obtained for the circularly polarized laser. The 3He polarization reached 70% and was stable over one week. A demonstration of the 3He nuclear spin flip system was performed at the polarized neutron reflectometer SHARAKU (BL17) and NOBORU (BL10) at J-PARC. Off-specular measurement from a magnetic Fe/Cr thin film and magnetic imaging of a magnetic steel sheet were performed at BL17 and BL10, respectively.

  1. Assessment of natural radioactivity and function of minerals in soils of Yelagiri hills, Tamilnadu, India by Gamma Ray spectroscopic and Fourier Transform Infrared (FTIR) techniques with statistical approach.

    PubMed

    Chandrasekaran, A; Ravisankar, R; Rajalakshmi, A; Eswaran, P; Vijayagopal, P; Venkatraman, B

    2015-02-05

    Gamma Ray and Fourier Transform Infrared (FTIR) spectroscopic techniques were used to evaluate the natural radioactivity due to natural radionuclides and mineralogical characterization in soils of Yelagiri hills, Tamilnadu, India. Various radiological parameters were calculated to assess the radiation hazards associated with the soil. The distribution pattern of activity due to natural radionuclides is explained by Kriging method of mapping. Using FTIR spectroscopic technique the minerals such as quartz, microcline feldspar, orthoclase feldspar, kaolinite, montmorillonite, illite, and organic carbon were identified and characterized. The extinction coefficient values were calculated to know the relative distribution of major minerals such as quartz, microcline feldspar, orthoclase feldspar and kaolinite. The calculated values indicate that the amount of quartz is higher than orthoclase feldspar, microcline feldspar and much higher than kaolinite. Crystallinity index was calculated to know the crystalline nature of quartz. The result indicates that the presence of disordered crystalline quartz in soils. The relation between minerals and radioactivity was assessed by multivariate statistical analysis (Pearson's correlation and cluster analysis). The statistical analysis confirms that the clay mineral kaolinite and non-clay mineral quartz is the major factor than other major minerals to induce the important radioactivity variables and concentrations of uranium and thorium. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Assessment of natural radioactivity and function of minerals in soils of Yelagiri hills, Tamilnadu, India by Gamma Ray spectroscopic and Fourier Transform Infrared (FTIR) techniques with statistical approach

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, A.; Ravisankar, R.; Rajalakshmi, A.; Eswaran, P.; Vijayagopal, P.; Venkatraman, B.

    2015-02-01

    Gamma Ray and Fourier Transform Infrared (FTIR) spectroscopic techniques were used to evaluate the natural radioactivity due to natural radionuclides and mineralogical characterization in soils of Yelagiri hills, Tamilnadu, India. Various radiological parameters were calculated to assess the radiation hazards associated with the soil. The distribution pattern of activity due to natural radionuclides is explained by Kriging method of mapping. Using FTIR spectroscopic technique the minerals such as quartz, microcline feldspar, orthoclase feldspar, kaolinite, montmorillonite, illite, and organic carbon were identified and characterized. The extinction coefficient values were calculated to know the relative distribution of major minerals such as quartz, microcline feldspar, orthoclase feldspar and kaolinite. The calculated values indicate that the amount of quartz is higher than orthoclase feldspar, microcline feldspar and much higher than kaolinite. Crystallinity index was calculated to know the crystalline nature of quartz. The result indicates that the presence of disordered crystalline quartz in soils. The relation between minerals and radioactivity was assessed by multivariate statistical analysis (Pearson's correlation and cluster analysis). The statistical analysis confirms that the clay mineral kaolinite and non-clay mineral quartz is the major factor than other major minerals to induce the important radioactivity variables and concentrations of uranium and thorium.

  3. Preparation techniques of the submicron lithium titanate materials by electro-spinning

    NASA Astrophysics Data System (ADS)

    Wang, Yudong; Yang, Kai; Gao, Fei; Liu, Hao; Zhang, Mingjie

    2017-01-01

    Combining sol-gel process and electro-spinning, the submicron lithium titanate materials are prepared with lithium acetate and titanium tetraisopropanolate respectively as the lithium and titanium sources, and polyvinylpyrrolidone (PVP) as the template. It's found by scanning electron microscope(SEM )that, the prepared lithium titanate materials are characterized by the fiber diameter 150~200nm, a large number of irregular indentations in the surface, and the larger specific surface area than that before calcination. The lithium titanate cell receives charge-discharge test and cyclic voltammetry. The capacity of the submicron lithium titanate materials is up to 160mAh·g-1 at the rate of 0.1C, and it's revealed by cyclic voltammetry that the cell in the charge or discharge process undergoes a single redox reaction, but having good reversibility.

  4. Identification of mitochondrial electron transport chain-mediated NADH radical formation by EPR spin-trapping techniques.

    PubMed

    Matsuzaki, Satoshi; Kotake, Yashige; Humphries, Kenneth M

    2011-12-20

    The mitochondrial electron transport chain (ETC) is a major source of free radical production. However, due to the highly reactive nature of radical species and their short lifetimes, accurate detection and identification of these molecules in biological systems is challenging. The aim of this investigation was to determine the free radical species produced from the mitochondrial ETC by utilizing EPR spin-trapping techniques and the recently commercialized spin-trap, 5-(2,2-dimethyl-1,3-propoxycyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO). We demonstrate that this spin-trap has the preferential quality of having minimal mitochondrial toxicity at concentrations required for radical detection. In rat heart mitochondria and submitochondrial particles supplied with NADH, the major species detected under physiological pH was a carbon-centered radical adduct, indicated by markedly large hyperfine coupling constant with hydrogen (a(H) > 2.0 mT). In the presence of the ETC inhibitors, the carbon-centered radical formation was increased and exhibited NADH concentration dependency. The same carbon-centered radical could also be produced with the NAD biosynthesis precursor, nicotinamide mononucleotide, in the presence of a catalytic amount of NADH. The results support the conclusion that the observed species is a complex I derived NADH radical. The formation of the NADH radical could be blocked by hydroxyl radical scavengers but not SOD. In vitro experiments confirmed that an NADH-radical is readily formed by hydroxyl radical but not superoxide anion, further implicating hydroxyl radical as an upstream mediator of NADH radical production. These findings demonstrate the identification of a novel mitochondrial radical species with potential physiological significance and highlight the diverse mechanisms and sites of production within the ETC.

  5. Spin-orbit scattering visualized in quasiparticle interference

    NASA Astrophysics Data System (ADS)

    Kohsaka, Y.; Machida, T.; Iwaya, K.; Kanou, M.; Hanaguri, T.; Sasagawa, T.

    2017-03-01

    In the presence of spin-orbit coupling, electron scattering off impurities depends on both spin and orbital angular momentum of electrons—spin-orbit scattering. Although some transport properties are subject to spin-orbit scattering, experimental techniques directly accessible to this effect are limited. Here we show that a signature of spin-orbit scattering manifests itself in quasiparticle interference (QPI) imaged by spectroscopic-imaging scanning tunneling microscopy. The experimental data of a polar semiconductor BiTeI are well reproduced by numerical simulations with the T -matrix formalism that include not only scalar scattering normally adopted but also spin-orbit scattering stronger than scalar scattering. To accelerate the simulations, we extend the standard efficient method of QPI calculation for momentum-independent scattering to be applicable even for spin-orbit scattering. We further identify a selection rule that makes spin-orbit scattering visible in the QPI pattern. These results demonstrate that spin-orbit scattering can exert predominant influence on QPI patterns and thus suggest that QPI measurement is available to detect spin-orbit scattering.

  6. Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer

    DOE PAGES

    Frank, Patrick; Szilagyi, Robert K.; Gramlich, Volker; ...

    2017-01-09

    Sulfur K-edge X-ray absorption spectroscopy (XAS) spectra of the monodentate sulfate complexes [MII(itao)(SO4)(H2O)0,1] (M = Co, Ni, Cu) and [Cu(Me6tren)(SO4)] exhibit well-defined preedge transitions at 2479.4, 2479.9, 2478.4, and 2477.7 eV, respectively, despite having no direct metal–sulfur bond, while the XAS preedge of [Zn(itao)(SO4)] is featureless. The sulfur K-edge XAS of [Cu(itao)(SO4)] but not of [Cu(Me6tren)(SO4)] uniquely exhibits a weak transition at 2472.1 eV, an extraordinary 8.7 eV below the first inflection of the rising K-edge. Preedge transitions also appear in the sulfur K-edge XAS of crystalline [MII(SO4)(H2O)] (M = Fe, Co, Ni, and Cu, but not Zn) and inmore » sulfates of higher-valent early transition metals. Ground-state density functional theory (DFT) and time-dependent DFT (TDDFT) calculations show that charge transfer from coordinated sulfate to paramagnetic late transition metals produces spin polarization that differentially mixes the spin-up (α) and spin-down (β) spin orbitals of the sulfate ligand, inducing negative spin density at the sulfate sulfur. Ground-state DFT calculations show that sulfur 3p character then mixes into metal 4s and 4p valence orbitals and various combinations of ligand antibonding orbitals, producing measurable sulfur XAS transitions. TDDFT calculations confirm the presence of XAS preedge features 0.5–2 eV below the rising sulfur K-edge energy. The 2472.1 eV feature arises when orbitals at lower energy than the frontier occupied orbitals with S 3p character mix with the copper(II) electron hole. Transmission of spin polarization and thus of radical character through several bonds between the sulfur and electron hole provides a new mechanism for the counterintuitive appearance of preedge transitions in the XAS spectra of transition-metal oxoanion ligands in the absence of any direct metal–absorber bond. The 2472.1 eV transition is evidence for further radicalization from copper(II), which extends across

  7. Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer.

    PubMed

    Frank, Patrick; Szilagyi, Robert K; Gramlich, Volker; Hsu, Hua-Fen; Hedman, Britt; Hodgson, Keith O

    2017-02-06

    Sulfur K-edge X-ray absorption spectroscopy (XAS) spectra of the monodentate sulfate complexes [M(II)(itao)(SO4)(H2O)0,1] (M = Co, Ni, Cu) and [Cu(Me6tren)(SO4)] exhibit well-defined preedge transitions at 2479.4, 2479.9, 2478.4, and 2477.7 eV, respectively, despite having no direct metal-sulfur bond, while the XAS preedge of [Zn(itao)(SO4)] is featureless. The sulfur K-edge XAS of [Cu(itao)(SO4)] but not of [Cu(Me6tren)(SO4)] uniquely exhibits a weak transition at 2472.1 eV, an extraordinary 8.7 eV below the first inflection of the rising K-edge. Preedge transitions also appear in the sulfur K-edge XAS of crystalline [M(II)(SO4)(H2O)] (M = Fe, Co, Ni, and Cu, but not Zn) and in sulfates of higher-valent early transition metals. Ground-state density functional theory (DFT) and time-dependent DFT (TDDFT) calculations show that charge transfer from coordinated sulfate to paramagnetic late transition metals produces spin polarization that differentially mixes the spin-up (α) and spin-down (β) spin orbitals of the sulfate ligand, inducing negative spin density at the sulfate sulfur. Ground-state DFT calculations show that sulfur 3p character then mixes into metal 4s and 4p valence orbitals and various combinations of ligand antibonding orbitals, producing measurable sulfur XAS transitions. TDDFT calculations confirm the presence of XAS preedge features 0.5-2 eV below the rising sulfur K-edge energy. The 2472.1 eV feature arises when orbitals at lower energy than the frontier occupied orbitals with S 3p character mix with the copper(II) electron hole. Transmission of spin polarization and thus of radical character through several bonds between the sulfur and electron hole provides a new mechanism for the counterintuitive appearance of preedge transitions in the XAS spectra of transition-metal oxoanion ligands in the absence of any direct metal-absorber bond. The 2472.1 eV transition is evidence for further radicalization from copper(II), which extends across a

  8. Potential energy curves and spectroscopic parameters of the 24 Λ-S states and 54 Ω states of the F2 + cation including the spin-orbit coupling effect*

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2016-11-01

    This work calculated the PECs of 24 Λ-S states and 54 Ω states of F2+ cation. The calculations were done with the CASSCF method, which was followed by the internally contracted MRCI approach. Core-valence correlation correction, scalar relativistic correction and basis set extrapolation were taken into account. Of these 24 Λ-S states, the 22Σg-, 22Σu-, 24Σg-, 14Δu, and 24Πg states were found to be repulsive. The X2Πg, A2Πu 14Δg, 14Πg and 24Πg states were found to be inverted with the spin-orbit coupling effect included. The 12Δg, 24Πu, 14Πg, 14Σu+, 22Πu, 14Σg-, 24Σu-, and 12Σg+ states were found to be weakly bound. The 24Σu- state had double wells. The avoided crossings of PECs were observed between the A2Πu and 22Πu states, the X2Πg and 22Πg states, the 12Σu- and 22Σu- states, the 14Πu and 24Πu states, and the 14Σ-g and 24Σ-g states. Some spectroscopic parameters were determined and the vibrational properties of several weakly-bound states were predicted. The spin-orbit coupling effect on the spectroscopic parameters was evaluated. Comparison with available experimental data shows that the methodology used in this paper is highly accurate for this system. Supplementary material in the form of one pdf file available from the Journal web page at: http://dx.doi.org/10.1140/epjd/e2016-70388-9

  9. Examination of optimum carrier materials and quantum dots for a quantum dot solar concentrator using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Gallagher, S. J.; Rowan, B. C.; Doran, J.; Norton, B.

    2005-08-01

    Spectroscopic measurements have been undertaken for a range of different quantum dot (QD) types and transparent host materials for use in a novel solar energy-concentrating device, a Quantum Dot Solar Concentrator1 (QDSC). A QDSC comprises QDs seeded in materials such as plastics and glasses that are suitable for incorporation into buildings where photovoltaic cells attached to the edges convert direct and diffuse solar energy into electricity for use in the building. High transparency in the matrix material and QDs with a large Stokes shift are essential for an efficient QDSC. An optimum matrix material for a QDSC has been determined based on absorption characteristics and an optimum commercially available QD type has been chosen using steady-state absorption, photoluminescence and photoluminescence excitation spectroscopy of QDs in solution and solid matrices.

  10. Identification of vegetable oil botanical speciation in refined vegetable oil blends using an innovative combination of chromatographic and spectroscopic techniques.

    PubMed

    Osorio, Maria Teresa; Haughey, Simon A; Elliott, Christopher T; Koidis, Anastasios

    2015-12-15

    European Regulation 1169/2011 requires producers of foods that contain refined vegetable oils to label the oil types. A novel rapid and staged methodology has been developed for the first time to identify common oil species in oil blends. The qualitative method consists of a combination of a Fourier Transform Infrared (FTIR) spectroscopy to profile the oils and fatty acid chromatographic analysis to confirm the composition of the oils when required. Calibration models and specific classification criteria were developed and all data were fused into a simple decision-making system. The single lab validation of the method demonstrated the very good performance (96% correct classification, 100% specificity, 4% false positive rate). Only a small fraction of the samples needed to be confirmed with the majority of oils identified rapidly using only the spectroscopic procedure. The results demonstrate the huge potential of the methodology for a wide range of oil authenticity work. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. A non-invasive thermal drift compensation technique applied to a spin-valve magnetoresistive current sensor.

    PubMed

    Sánchez Moreno, Jaime; Ramírez Muñoz, Diego; Cardoso, Susana; Casans Berga, Silvia; Navarro Antón, Asunción Edith; Peixeiro de Freitas, Paulo Jorge

    2011-01-01

    A compensation method for the sensitivity drift of a magnetoresistive (MR) Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC). No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensation has been solved in the interval from 0 °C to 70 °C measuring currents from -10 A to +10 A.

  12. Anomaly Detection Techniques with Real Test Data from a Spinning Turbine Engine-Like Rotor

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Woike, Mark R.; Oza, Nikunj C.; Matthews, Bryan L.

    2012-01-01

    Online detection techniques to monitor the health of rotating engine components are becoming increasingly attractive to aircraft engine manufacturers in order to increase safety of operation and lower maintenance costs. Health monitoring remains a challenge to easily implement, especially in the presence of scattered loading conditions, crack size, component geometry, and materials properties. The current trend, however, is to utilize noninvasive types of health monitoring or nondestructive techniques to detect hidden flaws and mini-cracks before any catastrophic event occurs. These techniques go further to evaluate material discontinuities and other anomalies that have grown to the level of critical defects that can lead to failure. Generally, health monitoring is highly dependent on sensor systems capable of performing in various engine environmental conditions and able to transmit a signal upon a predetermined crack length, while acting in a neutral form upon the overall performance of the engine system.

  13. A homonuclear spin-pair filter for solid-state NMR based on adiabatic-passage techniques

    NASA Astrophysics Data System (ADS)

    Verel, René; Baldus, Marc; Ernst, Matthias; Meier, Beat H.

    1998-05-01

    A filtering scheme for the selection of spin pairs (and larger spin clusters) under fast magic-angle spinning is proposed. The scheme exploits the avoided level crossing in spin pairs during an adiabatic amplitude sweep through the so-called HORROR recoupling condition. The advantages over presently used double-quantum filters are twofold. (i) The maximum theoretical filter efficiency is, due to the adiabatic variation, 100% instead of 73% as for transient methods. (ii) Since the filter does not rely on the phase-cycling properties of the double-quantum coherence, there is no need to obtain the full double-quantum intensity for all spins in the sample at one single point in time. The only important requirement is that all coupled spins pass through a two-spin state during the amplitude sweep. This makes the pulse scheme robust with respect to rf-amplitude missetting, rf-field inhomogeneity and chemical-shift offset.

  14. Investigation into the interaction of losartan with human serum albumin and glycated human serum albumin by spectroscopic and molecular dynamics simulation techniques: A comparison study.

    PubMed

    Moeinpour, Farid; Mohseni-Shahri, Fatemeh S; Malaekeh-Nikouei, Bizhan; Nassirli, Hooriyeh

    2016-09-25

    The interaction between losartan and human serum albumin (HSA), as well as its glycated form (gHSA) was studied by multiple spectroscopic techniques and molecular dynamics simulation under physiological conditions. The binding information, including the binding constants, effective quenching constant and number of binding sites showed that the binding partiality of losartan to HSA was higher than to gHSA. The findings of three-dimensional fluorescence spectra demonstrated that the binding of losartan to HSA and gHSA would alter the protein conformation. The distances between Trp residue and the binding sites of the drug were evaluated on the basis of the Förster theory, and it was indicated that non-radiative energy transfer from HSA and gHSA to the losartan happened with a high possibility. According to molecular dynamics simulation, the protein secondary and tertiary structure changes were compared in HSA and gHSA for clarifying the obtained results.

  15. Investigation on the interaction between isorhamnetin and bovine liver catalase by spectroscopic techniques under different pH conditions.

    PubMed

    Yang, Yumin; Li, Daojin

    2016-08-01

    The binding of isorhamnetin to bovine liver catalase (BLC) was first investigated at 302, 310 and 318 K at pH 7.4 using spectroscopic methods including fluorescence spectra, circular dichroism (CD) and UV-vis absorption. Spectrophotometric observations are rationalized mainly in terms of a static quenching process. The binding constants and binding sites were evaluated by fluorescence quenching methods. Enzymatic activity of BLC in the absence and presence of isorhamnetin was measured using a UV/vis spectrophotometer. The result revealed that the binding of isorhamnetin to BLC led to a reduction in the activity of BLC. The positive entropy change and enthalpy change indicated that the interaction of isorhamnetin with BLC was mainly driven by hydrophobic forces. The distance r between the donor (BLC) and acceptor (isorhamnetin) was estimated to be 2.99 nm according to fluorescence resonance energy transfer. Fluorescence, synchronous fluorescence, and CD spectra showed no obvious change in the conformation of BLC upon the binding of isorhamnetin. In addition, the influence of pH on the binding of isorhamnetin to BLC was investigated and the binding ability of the drug to BLC deceased under other pH conditions (pH 9.0, 6.5, 5.0, 3.5, or 2.0) as compared with that at pH 7.4. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Analytical performance of different X-ray spectroscopic techniques for the environmental monitoring of the recultivated uranium mine site

    NASA Astrophysics Data System (ADS)

    Alsecz, A.; Osán, J.; Kurunczi, S.; Alföldy, B.; Várhegyi, A.; Török, S.

    2007-08-01

    One uranium deposit exists in Hungary, with continuous radiological monitoring of the site. Nuclear spectroscopical methods are well established in order to study the problem concerning radionuclides. However, very limited information is available on the distribution and chemical form of uranium in the tailings sludge. In order to solve this complex analytical problem, a combination of different analytical methods is necessary. One of the most applied methods for studying the major elemental composition of particulate samples is electron probe microanalysis (EPMA). However, uranium and its daughter elements are often present only at trace amounts in the particles, below detection limit of EPMA. For most actinides that are long-lived radionuclides, microbeam X-ray fluorescence (μ-XRF) has superior sensitivity to determine elements in microparticles. Detection limits and applicability of EPMA and laboratory μ-XRF are discussed for localization of uranium-rich particles in the inhomogeneous tailings material. Laboratory μ-XRF provided an efficient way to identify these particles that can be easily relocated for further non-destructive microchemical investigations. Finally, for water analysis a simple and reliable method for U analysis is presented using total reflection X-ray fluorescence spectrometry (TXRF) that can be applied for on-site analysis in situations of accidental uranium contamination.

  17. Determination of photocarrier density under continuous photoirradiation using spectroscopic techniques as applied to polymer: Fullerene blend films

    NASA Astrophysics Data System (ADS)

    Kanemoto, Katsuichi; Nakatani, Hitomi; Domoto, Shinya

    2014-10-01

    We propose a method to determine the density of photocarrier under continuous photoirradiation in conjugated polymers using spectroscopic signals obtained by photoinduced absorption (PIA) measurements. The bleaching signals in the PIA measurements of polymer films and the steady-state absorption signals of oxidized polymer solution are employed to determine the photocarrier density. The method is applied to photocarriers of poly (3-hexylthiophene) (P3HT) in a blended film consisting of P3HT and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). The photocarrier density under continuous photoirradiation of 580 mW/cm2 is determined to be 3.5 × 1016 cm-3. Using a trend of the carrier density increasing in proportion to the square root of photo-excitation intensity, we provide a general formula to estimate the photocarrier density under simulated 1 sun solar irradiation for the P3HT: PCBM film of an arbitrary thickness. We emphasize that the method proposed in this study enables an estimate of carrier density without measuring a current and can be applied to films with no electrodes as well as to devices.

  18. Determination of photocarrier density under continuous photoirradiation using spectroscopic techniques as applied to polymer: Fullerene blend films

    SciTech Connect

    Kanemoto, Katsuichi Nakatani, Hitomi; Domoto, Shinya

    2014-10-28

    We propose a method to determine the density of photocarrier under continuous photoirradiation in conjugated polymers using spectroscopic signals obtained by photoinduced absorption (PIA) measurements. The bleaching signals in the PIA measurements of polymer films and the steady-state absorption signals of oxidized polymer solution are employed to determine the photocarrier density. The method is applied to photocarriers of poly (3-hexylthiophene) (P3HT) in a blended film consisting of P3HT and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). The photocarrier density under continuous photoirradiation of 580 mW/cm{sup 2} is determined to be 3.5 × 10{sup 16 }cm{sup −3}. Using a trend of the carrier density increasing in proportion to the square root of photo-excitation intensity, we provide a general formula to estimate the photocarrier density under simulated 1 sun solar irradiation for the P3HT: PCBM film of an arbitrary thickness. We emphasize that the method proposed in this study enables an estimate of carrier density without measuring a current and can be applied to films with no electrodes as well as to devices.

  19. Pressure effects and Mössbauer spectroscopic studies on a 3D mixed-valence iron spin-crossover complex with NiAs topology.

    PubMed

    Bai, Yue-Ling; Tao, Jun; Huang, Rong-Bin; Zheng, Lan-Sun; Zheng, Shao-Liang; Oshida, Kazuyoshi; Einaga, Yasuaki

    2008-04-21

    A three-dimensional mixed-valence iron complex with NiAs-type topology, [(Fe(III)(3)O)Fe(II)(TA)(6)(H(2)O)(3)].(ClO(4))(2)(NO(3))(EtOH)(H(2)O)(2) (1, HTA = tetrazole-1H-acetic acid), shows spin-crossover behavior that was characterized via variable-temperature crystal structures, Mössbauer spectra and magnetic susceptibilities, the pressure effects on the transition behavior were also studied.

  20. Response to the Letter to the Editor by D. Richardson: Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques

    PubMed Central

    Xu, Zhongjie; Liu, Youxun; Zhou, Sufeng; Fu, Yun; Li, Changzheng

    2016-01-01

    This response refers to: Xu, Z.; Liu, Y.; Zhou, S.; Fu, Y.; Li, C. Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques. Int. J. Mol. Sci. 2016, 17, 1042. Merlot, A.M.; Sahni, S.; Lane, D.J.R.; Richardson, V.; Huang, M.L.H.; Kalinowski, D.S.; Richardson, D.R. Letter to the Editor: Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques and. Int. J. Mol. Sci. 2016, 17, 1916. PMID:27854349

  1. Multisite evaluations of a T2 -relaxation-under-spin-tagging (TRUST) MRI technique to measure brain oxygenation.

    PubMed

    Liu, Peiying; Dimitrov, Ivan; Andrews, Trevor; Crane, David E; Dariotis, Jacinda K; Desmond, John; Dumas, Julie; Gilbert, Guillaume; Kumar, Anand; Maclntosh, Bradley J; Tucholka, Alan; Yang, Shaolin; Xiao, Guanghua; Lu, Hanzhang

    2016-02-01

    Venous oxygenation (Yv ) is an important index of brain physiology and may be indicative of brain diseases. A T2 -relaxation-under-spin-tagging (TRUST) MRI technique was recently developed to measure Yv . A multisite evaluation of this technique would be an important step toward broader availability and potential clinical utilizations of Yv measures. TRUST MRI was performed on a total of 250 healthy subjects, 125 from the developer's site and 25 each from five other sites. All sites were equipped with a 3 Tesla (T) MRI of the same vendor. The estimated Yv and the standard error (SE) of the estimation εYv were compared across sites. The averaged Yv and εYv across six sites were 61.1% ± 1.4% and 1.3% ± 0.2%, respectively. Multivariate regression analysis showed that the estimated Yv was dependent on age (P = 0.009) but not on performance site. In contrast, the SE of the Yv estimation was site-dependent (P = 0.024) but was less than 1.5%. Further analysis revealed that εYv was positively associated with the amount of subject motion (P < 0.001) but negatively associated with blood signal intensity (P < 0.001). This work suggests that TRUST MRI can yield equivalent results of Yv estimation across different sites. © 2015 Wiley Periodicals, Inc.

  2. Multi-site evaluations of a T2-Relaxation-Under-Spin-Tagging (TRUST) MRI technique to measure brain oxygenation

    PubMed Central

    Liu, Peiying; Dimitrov, Ivan; Andrews, Trevor; Crane, David E.; Dariotis, Jacinda K.; Desmond, John; Dumas, Julie; Gilbert, Guillaume; Kumar, Anand; Maclntosh, Bradley J.; Tucholka, Alan; Yang, Shaolin; Xiao, Guanghua; Lu, Hanzhang

    2015-01-01

    Purpose Venous oxygenation (Yv) is an important index of brain physiology and may be indicative of brain diseases. A T2-relaxation-under-spin-tagging (TRUST) MRI technique was recently developed to measure Yv. A multi-site evaluation of this technique would be an important step toward broader availability and potential clinical utilizations of Yv measures. Methods TRUST MRI was performed on a total of 250 healthy subjects, with 125 from the developer’s site and 25 each from five other sites. All sites were equipped with a 3T MRI of the same vendor. The estimated Yv and the standard error of the estimation, εYv, were compared across sites. Results The averaged Yv and εYv across six sites were 61.1±1.4% and 1.3±0.2%, respectively. Multivariate regression analysis showed that the estimated Yv was dependent on age (p=0.009), but not on performance site. In contrast, the standard error of Yv estimation was site-dependent (p=0.024), but was all less than 1.5%. Further analysis revealed that εYv was positively associated with the amount of subject motion (p<0.001) but negatively associated with blood signal intensity (p<0.001). Conclusion This work suggests that TRUST MRI can yield equivalent results of Yv estimation across different sites. PMID:25845468

  3. Influence of selenization temperature on the properties of CuInSe2 thin films prepared by spin coating technique

    NASA Astrophysics Data System (ADS)

    Merdes, S.; Bechiri, L.; Hadjoub, Z.; Sano, M.; Ando, S.

    2006-09-01

    CuInSe2 (CIS) polycrystalline thin films have been prepared using the spin coating technique by thermal decomposition in N2+H2 (10%) gas of Cu-In Naphthenates and subsequent selenization in vacuum sealed ampoules of the obtained precursors with Se vapor. This technique which requires low vacuum process and low cost processing equipment is suitable for obtaining large area films and mass production. In this paper we report on the influence of selenization temperature on the growth process. Thus, samples have been prepared with different precursor compositions and selenized at various temperatures. A post-growth annealing has also been carried out. Crystal growth was followed versus the different selenization temperatures until the formation of CuInSe2 phase. Structure, crystal orientation and morphology of the obtained experimental films were studied by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). Polycrystalline films with a single (112) mainly oriented chalcopyrite phase have been obtained.

  4. Spin transition in Gd3N@C80, detected by low-temperature on-chip SQUID technique

    NASA Astrophysics Data System (ADS)

    Chen, L.; Carpenter, E. E.; Hellberg, C. S.; Dorn, H. C.; Shultz, M.; Wernsdorfer, W.; Chiorescu, I.

    2011-04-01

    We present a magnetic study of the Gd3N@C80 molecule, consisting of a Gd-trimer via a nitrogen atom, encapsulated in a C80 cage. This molecular system can be an efficient contrast agent for magnetic resonance imaging (MRI) applications. We used a low-temperature technique able to detect small magnetic signals by placing the sample in the vicinity of an on-chip SQUID. The technique implemented at the National High Magnetic Field Laboratory has the particularity of being able to operate in high magnetic fields of up to 7 T. The Gd3N@C80 shows a paramagnetic behavior and we find a spin transition of the Gd3N structure at 1.2 K. We perform quantum mechanical simulations, which indicate that one of the Gd ions changes from a 8S7/2 state (L = 0, S = 7/2) to a 7F6 state (L = S = 3, J = 6), likely due to a charge transfer between the C80 cage and the ion.

  5. Direct observation of hopping induced spin polarization current in oxygen deficient Co-doped ZnO by Andreev reflection technique

    NASA Astrophysics Data System (ADS)

    Yang, Kung-Shang; Huang, Tzu-Yu; Dwivedi, G. D.; Lin, Lu-Kuei; Lee, Shang-Fan; Sun, Shih-Jye; Chou, Hsiung

    2017-07-01

    Oxygen vacancy induced ferromagnetic coupling in diluted magnetic oxide (DMO) semiconductors have been reported in several studies, but technologically more crucial spin-polarized current (SPC) is still under-developed in DMOs. Few studies have claimed that VRH mechanism can originate the SPC, but, how VRH mechanism associated with percolation path, is not clearly understood. We used Point-contact Andreev reflection (PCAR) technique to probe the SPC in Co-doped ZnO (CZO) films. Since the high resistance samples cause broadening in conductance(G)-voltage(V) curves, which may result in an unreliable evaluation of spin polarization, we include two extra parameters, (i) effective temperature and (ii) spreading resistance, for the simulation to avoid the uncertainty in extracting spin polarization. The effective G-V curves and higher spin polarization can be obtained above a certain oxygen vacancy concentration. The number of completed and fragmentary percolation paths is proportional to the concentration of oxygen vacancies. For low oxygen vacancy samples, the Pb-tip has a higher probability of covering fragmentary percolation paths than the complete ones, due to its small contact size. The completed paths may remain independent of one another and get polarized in different directions, resulting in lower spin-polarization value. High oxygen vacancy samples provide a high density of completed path, most of them link to one another by crossing over, and gives rise to high spin-polarization value.

  6. Derivatives of pyrazinecarboxylic acid: 1H, 13C and 15N NMR spectroscopic investigations.

    PubMed

    Holzer, Wolfgang; Eller, Gernot A; Datterl, Barbara; Habicht, Daniela

    2009-07-01

    NMR spectroscopic studies are undertaken with derivatives of 2-pyrazinecarboxylic acid. Complete and unambiguous assignment of chemical shifts ((1)H, (13)C, (15)N) and coupling constants ((1)H,(1)H; (13)C,(1)H; (15)N,(1)H) is achieved by combined application of various 1D and 2D NMR spectroscopic techniques. Unequivocal mapping of (13)C,(1)H spin coupling constants is accomplished by 2D (delta,J) long-range INEPT spectra with selective excitation. Phenomena such as the tautomerism of 3-hydroxy-2-pyrazinecarboxylic acid are discussed.

  7. Study of hydrogen-bonding, vibrational dynamics and structure-activity relationship of genistein using spectroscopic techniques coupled with DFT

    NASA Astrophysics Data System (ADS)

    Singh, Harshita; Singh, Swapnil; Srivastava, Anubha; Tandon, Poonam; Bharti, Purnima; Kumar, Sudhir; Dev, Kapil; Maurya, Rakesh

    2017-02-01

    The conformational and hydrogen bonding studies of genistein have been performed by combined spectroscopic and quantum chemical approach. The vibrational spectra (FT-IR and FT-Raman), UV-visible and 1H and 13C NMR absorption spectra of genistein have been recorded and examined. The vibrational wavenumbers of optimized geometry and total energy for isolated molecule and hydrogen-bonded dimers of genistein have been determined using the quantum chemical calculation (DFT/B3LYP) with extended 6-311++G (d,p) basis set. The vibrational assignments for the observed FT-IR and FT-Raman spectra of genistein are provided by calculations on monomer and hydrogen-bonded dimer. The quantum theory of atoms in molecules (QTAIM) is used for investigating the nature and strength of hydrogen-bonds. UV-visible spectrum of the genistein was recorded in methanol solvent and the electronic properties were calculated by using time-dependent density functional theory (TD-DFT). The computed HOMO and LUMO energies predicted the type of transition as π → π*. The 1H and 13C NMR signals of the genistein were computed by the Gauge including atomic orbital (GIAO) approach. Natural bond orbital (NBO) analysis predicted the stability of molecules due to charge delocalization and hyper conjugative interactions. NBO analysis shows that there is an Osbnd H⋯O inter and intramolecular hydrogen bond, and π → π* transition in the monomer and dimer, which is consistent with the conclusion obtained by the investigation of molecular structure and assignment of UV-visible spectra.

  8. RHIC SPIN FLIPPER

    SciTech Connect

    BAI,M.; ROSER, T.

    2007-06-25

    This paper proposes a new design of spin flipper for RHIC to obtain full spin flip with the spin tune staying at half integer. The traditional technique of using an rf dipole or solenoid as spin flipper to achieve full spin flip in the presence of full Siberian snake requires one to change the snake configuration to move the spin tune away from half integer. This is not practical for an operational high energy polarized proton collider like RHIC where beam lifetime is sensitive to small betatron tune change. The design of the new spin flipper as well as numerical simulations are presented.

  9. Multidisciplinary approach for the study of an Egyptian coffin (late 22nd/early 25th dynasty): Combining imaging and spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Bracci, S.; Caruso, O.; Galeotti, M.; Iannaccone, R.; Magrini, D.; Picchi, D.; Pinna, D.; Porcinai, S.

    2015-06-01

    This paper demonstrates that an educated methodology based on both non-invasive and micro invasive techniques in a two-step approach is a powerful tool to characterize the materials and stratigraphies of an Egyptian coffin, which was restored several times. This coffin, belonging to a certain Mesiset, is now located at the Museo Civico Archeologico of Bologna (inventory number MCABo EG 1963). Scholars attributed it to the late 22nd/early 25th dynasty by stylistic comparison. The first step of the diagnostic approach applied imaging techniques on the whole surface in order to select measurements spots and to unveil both original and restored areas. Images and close microscopic examination of the polychrome surface allowed selecting representative areas to be investigated in situ by portable spectroscopic techniques: X-ray Fluorescence (XRF), Fiber Optic Reflectance Spectroscopy (FORS) and Fourier Transform Infrared spectroscopy (FTIR). After the analysis of the results coming from the first step, very few selected samples were taken to clarify the stratigraphy of the polychrome layers. The first step, based on the combination of imaging and spectroscopic techniques in a totally non-invasive modality, is quite unique in the literature on Egyptian coffins and enabled us to reveal many differences in the ground layer's composition and to identify a remarkable number of pigments in the original and restored areas. This work offered also a chance to check the limitations of the non-invasive approach applied on a complex case, namely the right localization of different materials in the stratigraphy and the identification of binding media. Indeed, to dissolve any remaining doubts on superimposed layers belonging to different interventions, it was necessary to sample few micro-fragments in some selected areas and analyze them prepared as cross-sections. The original ground layer is made of calcite, while the restored areas show the presence of either a mixture of calcite

  10. Multidisciplinary approach for the study of an Egyptian coffin (late 22nd/early 25th dynasty): combining imaging and spectroscopic techniques.

    PubMed

    Bracci, S; Caruso, O; Galeotti, M; Iannaccone, R; Magrini, D; Picchi, D; Pinna, D; Porcinai, S

    2015-06-15

    This paper demonstrates that an educated methodology based on both non-invasive and micro invasive techniques in a two-step approach is a powerful tool to characterize the materials and stratigraphies of an Egyptian coffin, which was restored several times. This coffin, belonging to a certain Mesiset, is now located at the Museo Civico Archeologico of Bologna (inventory number MCABo EG 1963). Scholars attributed it to the late 22nd/early 25th dynasty by stylistic comparison. The first step of the diagnostic approach applied imaging techniques on the whole surface in order to select measurements spots and to unveil both original and restored areas. Images and close microscopic examination of the polychrome surface allowed selecting representative areas to be investigated in situ by portable spectroscopic techniques: X-ray Fluorescence (XRF), Fiber Optic Reflectance Spectroscopy (FORS) and Fourier Transform Infrared spectroscopy (FTIR). After the analysis of the results coming from the first step, very few selected samples were taken to clarify the stratigraphy of the polychrome layers. The first step, based on the combination of imaging and spectroscopic techniques in a totally non-invasive modality, is quite unique in the literature on Egyptian coffins and enabled us to reveal many differences in the ground layer's composition and to identify a remarkable number of pigments in the original and restored areas. This work offered also a chance to check the limitations of the non-invasive approach applied on a complex case, namely the right localization of different materials in the stratigraphy and the identification of binding media. Indeed, to dissolve any remaining doubts on superimposed layers belonging to different interventions, it was necessary to sample few micro-fragments in some selected areas and analyze them prepared as cross-sections. The original ground layer is made of calcite, while the restored areas show the presence of either a mixture of calcite

  11. Parametrization of the magnetic behavior of the triangular spin ladder chains organically templated: (C2N2H10)[M(HPO3)F3] (M(III) = Fe, Cr, and V). Crystal structure and thermal and spectroscopic properties of the iron(III) phase.

    PubMed

    Fernández-Armas, Sergio; Mesa, José L; Pizarro, José L; Clemente-Juan, Juan Modesto; Coronado, Eugenio; Arriortua, María I; Rojo, Teófilo

    2006-04-17

    A new iron(III) phosphite templated by ethylenediamine has been synthesized using solvothermal conditions under autogenous pressure. The (C2N2H10)[Fe(HPO3)F3] compound has been characterized by single-crystal X-ray diffraction data and spectroscopic and magnetic techniques. The crystal structure is formed by chains extended along the c axis and surrounded by ethylenediammonium cations. A study by diffuse-reflectance spectroscopy has been performed, and the calculated Dq, B, and C parameters for the Fe(III) cations are 1030, 720, and 3080 cm(-1), respectively. The Mössbauer spectrum at room temperature is characteristic of Fe(III) ions. The electron spin resonance (ESR) spectra carried out at different temperatures show isotropic signals with a g value of 2.00(1). The thermal evolution of the intensity of the ESR signals indicates the existence of antiferromagnetic interactions for the Fe(III) phase. The magnetic susceptibility data of the Cr(III) and V(III) compounds show antiferromagnetic couplings. The J-exchange parameters of the Fe(III) and Cr(III) compounds have been calculated by using a model for a triangular spin ladder chain. The values are J1 = -1.63(1) K and J2 = -0.87(2) K with g = 2.02 for the Fe(III) phase and J(1) = -0.56(2) K and J2 = -0.40(2) K with g = 1.99 for the Cr(III) compound. In the case of the V(III) phase, the fit has been performed considering a linear chain with the magnetic parameters D = 2.5 cm(-1) and J = -1.15(1) K.

  12. Determination of Two-Photon Absorption Cross-Section of Noble Gases for Calibration of Laser Spectroscopic Techniques

    SciTech Connect

    Rosa, M. I. de la; Perez, C.; Gruetzmacher, K.; Fuentes, L. M.

    2008-10-22

    The objective of our work is to apply two-photon polarization spectroscopy as a new calibration method for the determination of two-photon excitation cross-sections of noble gases, like Xe and Kr, which are commonly used for calibrations of MP-LIF techniques in other laboratories.

  13. Comprehensive analysis of TEM methods for LiFePO4/FePO4 phase mapping: spectroscopic techniques (EFTEM, STEM-EELS) and STEM diffraction techniques (ACOM-TEM).

    PubMed

    Mu, X; Kobler, A; Wang, D; Chakravadhanula, V S K; Schlabach, S; Szabó, D V; Norby, P; Kübel, C

    2016-11-01

    Transmission electron microscopy (TEM) has been used intensively in investigating battery materials, e.g. to obtain phase maps of partially (dis)charged (lithium) iron phosphate (LFP/FP), which is one of the most promising cathode material for next generation lithium ion (Li-ion) batteries. Due to the weak interaction between Li atoms and fast electrons, mapping of the Li distribution is not straightforward. In this work, we revisited the issue of TEM measurements of Li distribution maps for LFP/FP. Different TEM techniques, including spectroscopic techniques (energy filtered (EF)TEM in the energy range from low-loss to core-loss) and a STEM diffraction technique (automated crystal orientation mapping (ACOM)), were applied to map the lithiation of the same location in the same sample. This enabled a direct comparison of the results. The maps obtained by all methods showed excellent agreement with each other. Because of the strong difference in the imaging mechanisms, it proves the reliability of both the spectroscopic and STEM diffraction phase mapping. A comprehensive comparison of all methods is given in terms of information content, dose level, acquisition time and signal quality. The latter three are crucial for the design of in-situ experiments with beam sensitive Li-ion battery materials. Furthermore, we demonstrated the power of STEM diffraction (ACOM-STEM) providing additional crystallographic information, which can be analyzed to gain a deeper understanding of the LFP/FP interface properties such as statistical information on phase boundary orientation and misorientation between domains.

  14. Advanced Spectroscopic Synchrotron Techniques to Unravel the Intrinsic Properties of Dilute Magnetic Oxides: The Case of Co:ZnO

    SciTech Connect

    Ney, A; Opel, M; Kaspar, Tiffany C; Ney, V; Ye, S; Ollefs, K; Kammermeier, T; Bauer, S; Nielsen, K W; Goennenwein, S Tb; Engelhard, Mark H; Zhou, S; Potzger, K; Simon, J; Mader, W; Heald, Steve M; Cezar, J C; Wilhelm, F; Rogalev, A; Gross, R; Chambers, Scott A

    2010-01-22

    The use of synchrotron-based spectroscopy has revolutionized the way we look at matter. X-ray absorption spectroscopy (XAS) using linear and circular polarized light offers a powerful toolbox of element-specific structural, electronic, and magnetic probes that is especially well suited for complex materials containing several elements. We use the specific example of Zn1-xCoxO (Co:ZnO) to demonstrate the usefulness of combining these XAS techniques to unravel its intrinsic properties. We are able to demonstrate, that as long as phase separation or excessive defect formation is absent Co:ZnO is paramagnetic and we can establish independent quality indicators based on XAS. Samples which show long-range magnetic order fail to meet the quality indicators and complementary experimental techniques such as x-ray diffraction and transmission electron microscopy indeed prove phase separation. By deconvoluting the XAS spectra, the characteristic spectral features of the phase separated materials are derived.

  15. Electrical and optical properties of p-type codoped ZnO thin films prepared by spin coating technique

    NASA Astrophysics Data System (ADS)

    Pathak, Trilok Kumar; Kumar, Vinod; Swart, H. C.; Purohit, L. P.

    2016-03-01

    Undoped, doped and codoped ZnO thin films were synthesized on glass substrates using a spin coating technique. Zinc acetate dihydrate, ammonium acetate and aluminum nitrate were used as precursor for zinc, nitrogen and aluminum, respectively. X-ray diffraction shows that the thin films have a hexagonal wurtzite structure for the undoped, doped and co-doped ZnO. The transmittance of the films was above 80% and the band gap of the film varied from 3.20 eV to 3.24 eV for undoped and doped ZnO. An energy band diagram to describe the photoluminescence from the thin films was also constructed. This diagram includes the various defect levels and possible quasi-Fermi levels. A minimum resistivity of 0.0834 Ω-cm was obtained for the N and Al codoped ZnO thin films with p-type carrier conductivity. These ZnO films can be used as a window layer in solar cells and in UV lasers.

  16. Concentration influence on structural and optical properties of SnO2 thin films synthesized by the spin coating technique.

    NASA Astrophysics Data System (ADS)

    Belhamri, Soumia; Hamdadou, Nasr-Eddine

    2016-10-01

    Tin dioxide is an n-type semiconductor, with wide band gap 3.6 eV and special properties such as high optical transmission in the visible range, the infrared reflection and chemical stability. The objective of our work is to study the effect of solution concentration on the properties of SnO2 thin films, which were deposited on glass substrate by sol-gel spin coating technique and characterized by X-ray diffraction, UV-visible spectroscopy after annealing for one hour at 500°C. X ray diffraction spectra (XRD) showed that the films deposited at different concentrations (0.7 mol/l, 1 mol/l, 1.5 mol/l) are polycrystalline with a rutile type tetragonal. The grains have two preferred orientations along the directions (110) and (101) corresponding to 2θ = 26,744° and 34,113° respectively. We have also noted that the grain size change between 20 and 40 nm. The peak of diffraction becomes less intense when the solution concentration is more than 0.7 mol / l. The opticall transmittance of the films in the visible spectrum was in the range of 59 - 44%.

  17. Polymer structure and antimicrobial activity of polyvinylpyrrolidone-based iodine nanofibers prepared with high-speed rotary spinning technique.

    PubMed

    Sebe, István; Szabó, Barnabás; Nagy, Zsombor K; Szabó, Dóra; Zsidai, László; Kocsis, Béla; Zelkó, Romána

    2013-12-15

    Poly(vinylpyrrolidone)/poly(vinylpyrrolidone-vinylacetate)/iodine nanofibers of different polymer ratios were successfully prepared by a high-speed rotary spinning technique. The obtained fiber mats were subjected to detailed morphological analysis using an optical and scanning electron microscope (SEM), while the supramolecular structure of the samples was analyzed by positron annihilation lifetime spectroscopy (PALS). The maximum dissolved iodine of the fiber samples was determined, and microbiological assay was carried out to test their effect on the bacterial growth. SEM images showed that the polymer fibers were linear, homogenous, and contained no beads. The PALS results, both the o-positronium (o-Ps) lifetime values and distributions, revealed the changes of the free volume holes of fibers as a function of their composition and the presence of iodine. The micro- and macrostructural characterisation of polymer fiber mats enabled the selection of the required composition from the point of their applicability as a wound dressing. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Thermoelectric properties of Si/CoSi2 sub-micrometer composites prepared by melt-spinning technique

    NASA Astrophysics Data System (ADS)

    Xie, Jun; Ohishi, Yuji; Ichikawa, Satoshi; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke

    2017-05-01

    We here report on the influence of CoSi2 precipitates on the thermoelectric properties of heavily doped p-type Si. A simple self-assembly process using a melt-spinning technique followed by spark plasma sintering is introduced to prepare bulk Si/CoSi2 composites with a nominal composition of (Si0.99B0.01)95Co5. Scanning and transmission electron microscopy observations present clear evidence of a sub-micrometer CoSi2 phase with a size ranging from 50 to 500 nm. These sub-micrometer precipitates resulted in a retention of the high electrical performance of heavily doped Si, while simultaneously reducing thermal conductivity by over 20% compared to a coarse CoSi2 phase (1-10 μm) in a comparative sample prepared by arc melting and spark plasma sintering. As a result, a figure of merit ZT value of 0.21 at 1073 K was achieved in the sub-micrometer Si/CoSi2, an increase of 16% compared with the ZT value for homogeneous p-type Si with a similar carrier concentration. This suggests that the self-assembled sub-micrometer inclusions effectively enhanced the thermoelectric performance of Si-based thermoelectric materials.

  19. On-line preferential solvation studies of polymers by coupled chromatographic-Fourier transform infrared spectroscopic flow-cell technique.

    PubMed

    Malanin, M; Eichhorn, K-J; Lederer, A; Treppe, P; Adam, G; Fischer, D; Voigt, D

    2009-12-18

    Qualitative and quantitative comparison between liquid chromatography (LC) and LC coupled with Fourier transform infrared spectroscopy (LC-FTIR) to evaluate preferential solvation phenomenon of polymers in a mixed solvent has been performed. These studies show that LC-FTIR technique leads to detailed structural information without the requirement for determination of additional parameters for quantitative analysis except calibration. Appropriate experimental conditions for preferential solvation study have been established by variation of polymer concentration, molar mass and eluent content.

  20. One-step Multiple Component Isolation from the Oil of Crinitaria tatarica (Less.) Sojak by Preparative Capillary Gas Chromatography with Characterization by Spectroscopic and Spectrometric Techniques and Evaluation of Biological Activity

    DTIC Science & Technology

    2012-01-01

    20] Adams, R. P., Identification of Essential Oil Components by Gas Chromatography /Mass Spectrometry, Allured Publishing Corporation, Carol Stream... chromatography with characterization by spectroscopic and spectrometric techniques and evaluation of biological activity Gas chromatographic analysis revealed...step multiple fractionation of the oil and separation of two unknown constituents were performed using preparative capillary gas chromatography

  1. Evaluation of structure-reactivity descriptors and biological activity spectra of 4-(6-methoxy-2-naphthyl)-2-butanone using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Agrawal, Megha; Deval, Vipin; Gupta, Archana; Sangala, Bagvanth Reddy; Prabhu, S. S.

    2016-10-01

    The structure and several spectroscopic features along with reactivity parameters of the compound 4-(6-methoxy-2-naphthyl)-2-butanone (Nabumetone) have been studied using experimental techniques and tools derived from quantum chemical calculations. Structure optimization is followed by force field calculations based on density functional theory (DFT) at the B3LYP/6-311++G(d,p) level of theory. The vibrational spectra have been interpreted with the aid of normal coordinate analysis. UV-visible spectrum and the effect of solvent have been discussed. The electronic properties such as HOMO and LUMO energies have been determined by TD-DFT approach. In order to understand various aspects of pharmacological sciences several new chemical reactivity descriptors - chemical potential, global hardness and electrophilicity have been evaluated. Local reactivity descriptors - Fukui functions and local softnesses have also been calculated to find out the reactive sites within molecule. Aqueous solubility and lipophilicity have been calculated which are crucial for estimating transport properties of organic molecules in drug development. Estimation of biological effects, toxic/side effects has been made on the basis of prediction of activity spectra for substances (PASS) prediction results and their analysis by Pharma Expert software. Using the THz-TDS technique, the frequency-dependent absorptions of NBM have been measured in the frequency range up to 3 THz.

  2. Spectroscopic Evidence for Strong Quantum Spin Fluctuations with Itinerant Character in YFe2Ge2

    SciTech Connect

    Sirica, N.; Bondino, F.; Nappini, S.; Piz, I.; Poudel, L.; Christianson, Andrew D.; Mandrus, D.; Singh, David J; Mannella, Norman

    2015-03-04

    We report x-ray absorption and photoemission spectroscopy of the electronic structure in the normal state of metallic YFe2Ge2. The data reveal evidence for large fluctuating spin moments on the Fe sites, as indicated by exchange multiplets appearing in the Fe 3s core-level photoemission spectra, even though the compound does not show magnetic order. The magnitude of the multiplet splitting is comparable to that observed in the normal state of the Fe-pnictide superconductors. This shows a connection between YFe2Ge2 and the Fe-based superconductors even though it contains neither pnictogens nor chalcogens. Finally, the implication is that the chemical range of compounds showing at least one of the characteristic magnetic signatures of the Fe-based superconductors is broader than previously thought.

  3. In vivo optical analysis of pancreatic cancer tissue in living model mice using fluorescence and Raman spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshiaki; Hattori, Yusuke; Katagiri, Takashi; Mitsuoka, Hiroki; Sato, Ken-ichi; Asakura, Toru; Shimosegawa, Toru; Sato, Hidetoshi

    2009-02-01

    Living pancreatic cancer tissues grown subcutaneously in nude mice are studied by in vivo Raman spectroscopy and autofluorescence imaging. Comparing the same point spectra of alive pancreatic cancer tissue to that of the dead tissue, it is found that they are different each other. The results suggest that the spectral changes reflect the protein conformational changes in the tumor tissue with death of the host animal. From the result of autofluorescence study, in vivo autofluorescence imaging has potential as a method to assign the histological elements of the pancreatic cancer tissue without any staining. These results strongly suggest that combination of these techniques is very important to study biological tissue.

  4. Determining the mode of interaction of calf thymus DNA with the drug sumatriptan using voltammetric and spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Shahabadi, Nahid; Moghadam, Neda Hosseinpour

    2012-12-01

    The interaction of native calf thymus DNA with sumatriptan(1-[3-(2-dimethylaminoethyl)-1H-indol-5-yl]-N-methyl-methanesulfonamide) at physiological pH was studied by spectrophotometry, circular dichroism, voltammetry and viscosimetric techniques. Sumatriptan molecule intercalated between base pairs of DNA, showed by a sharp increase in specific viscosity of DNA. In cyclic voltammetry, decrease of the peak current and positive shift indicated that this drug is able to intercalate between the DNA base pairs. In addition, the drug induced changes in the CD spectrum of CT-DNA, as well as hypochromism changes in its UV-vis spectrum.

  5. Advanced spectroscopic synchrotron techniques to unravel the intrinsic properties of dilute magnetic oxides : the case of Co:ZnO.

    SciTech Connect

    Ney, A.; Opel, M.; Kaspar, T. C.; Ney, V.; Ye, S.; Ollefs, K.; Kammermeier, T.; Bauer, S.; Nielsen, K.-W.; Goennenwein, S. T. B.; Engelhard, M. H.; Zhou, S.; Potzger, K.; Simon, J.; Mader, W.; Heald, S. M.; Cezar, C.; Wilhelm, F.; Rogalev, A.; Gross, R.; Chambers, S. A.; X-Ray Science Division; Univ. at Duisburg-Essen; Walther-Meibner-Inst.; PNNL; Inst.fur Ionenstrahlphysik und Materialforschung; European Synchrotron Radiation Facility; Friedrich-Wilhelms-Univ.

    2010-02-01

    The use of synchrotron-based spectroscopy has revolutionized the way we look at matter. X-ray absorption spectroscopy (XAS) using linear and circular polarized light offers a powerful toolbox of element-specific structural, electronic and magnetic probes that is especially well suited for complex materials containing several elements. We use the specific example of Zn{sub 1-x}Co{sub x}O (Co:ZnO) to demonstrate the usefulness of combining these XAS techniques to unravel its intrinsic properties. We demonstrate that as long as phase separation or excessive defect formation is absent, Co:ZnO is paramagnetic. We can establish quantitative thresholds based on four reliable quality indicators using XAS; samples that show ferromagnet-like behaviour fail to meet these quality indicators, and complementary experimental techniques indeed prove phase separation. Careful analysis of XAS spectra is shown to provide quantitative information on the presence and type of dilute secondary phases in a highly sensitive, non-destructive manner.

  6. Evaluating the abnormal ossification in tibiotarsi of developing chick embryos exposed to 1.0ppm doses of platinum group metals by spectroscopic techniques.

    PubMed

    Stahler, Adam C; Monahan, Jennifer L; Dagher, Jessica M; Baker, Joshua D; Markopoulos, Marjorie M; Iragena, Diane B; NeJame, Britney M; Slaughter, Robert; Felker, Daniel; Burggraf, Larry W; Isaac, Leon A C; Grossie, David; Gagnon, Zofia E; Sizemore, Ioana E Pavel

    2013-04-01

    Platinum group metals (PGMs), i.e., palladium (Pd), platinum (Pt) and rhodium (Rh), are found at pollutant levels in the environment and are known to accumulate in plant and animal tissues. However, little is known about PGM toxicity. Our previous studies showed that chick embryos exposed to PGM concentrations of 1mL of 5.0ppm (LD50) and higher exhibited severe skeletal deformities. This work hypothesized that 1.0ppm doses of PGMs will negatively impact the mineralization process in tibiotarsi. One milliliter of 1.0ppm of Pd(II), Pt(IV), Rh(III) aqueous salt solutions and a PGM-mixture were injected into the air sac on the 7th and 14th day of incubation. Control groups with no-injection and vehicle injections were included. On the 20th day, embryos were sacrificed to analyze the PGM effects on tibiotarsi using four spectroscopic techniques. 1) Micro-Raman imaging: Hyperspectral Raman data were collected on paraffin embedded cross-sections of tibiotarsi, and processed using in-house-written MATLAB codes. Micro-Raman univariate images that were created from the ν1(PO4(3-)) integrated areas revealed anomalous mineral inclusions within the bone marrow for the PGM-mixture treatment. The age of the mineral crystals (ν(CO3(2-))/ν1(PO4(3-))) was statistically lower for all treatments when compared to controls (p≤0.05). 2) FAAS: The percent calcium content of the chemically digested tibiotarsi in the Pd and Pt groups changed by ~45% with respect to the no-injection control (16.1±0.2%). 3) Micro-XRF imaging: Abnormal calcium and phosphorus inclusions were found within the inner longitudinal sections of tibiotarsi for the PGM-mixture treatment. A clear increase in the mineral content was observed for the outer sections of the Pd treatment. 4) ICP-OES: PGM concentrations in tibiotarsi were undetectable (<5ppb). The spectroscopic techniques gave corroborating results, confirmed the hypothesis, and explained the observed pathological (skeletal developmental abnormalities

  7. Observational and laboratory studies of optical properties of black and brown carbon particles in the atmosphere using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Nakayama, Tomoki; Matsumi, Yutaka

    2015-04-01

    Light absorption and scattering by aerosols are as an important contributor to radiation balance in the atmosphere. Black carbon (BC) is considered to be the most potent light absorbing material in the visible region of the spectrum, although light absorbing organic carbon (brown carbon or BrC) and mineral dust may also act as sources of significant absorption, especially in the ultraviolet (UV) and shorter visible wavelength regions. The optical properties of such particles depend on wavelength, particle size and shape, morphology, coating, and complex refractive index (or chemical composition), and therefore accurate in situ measurements of the wavelength dependence of the optical properties of particles are needed. Recently, cavity ring-down spectroscopy (CRDS) and photoacoustic spectroscopy (PAS) have been used for the direct measurements of extinction and absorption coefficients of particles suspended in air. We have applied these techniques to the observational studies of optical properties of BC and BrC in an urban site in Japan and to the laboratory studies of optical properties of secondary organic aerosols (SOAs) generated from a variety of biogenic and anthropogenic volatile organic compounds and those of diesel exhaust particles (DEPs). In the presentation, the basic principles of these techniques and the results obtained in our studies and in the recent literatures will be overviewed. References Guo, X. et al., Measurement of the light absorbing properties of diesel exhaust particles using a three-wavelength photoacoustic spectrometer, Atmos. Environ., 94, 428-437 (2014). Nakayama, T. et al., Measurements of aerosol optical properties in central Tokyo during summertime using cavity ring-down spectroscopy: Comparison with conventional techniques, Atmos. Environ., 44, 3034-3042 (2010). Nakayama, T. et al., Laboratory studies on optical properties of secondary organic aerosols generated during the photooxidation of toluene and the ozonolysis of alpha

  8. A new approach for the modelling of chestnut wood photo-degradation monitored by different spectroscopic techniques.

    PubMed

    Bonifazi, G; Calienno, L; Capobianco, G; Monaco, A Lo; Pelosi, C; Picchio, R; Serranti, S

    2017-06-01

    The aim of this work is to study the colour and chemical modifications of the surfaces in chestnut wood samples as a consequence of irradiating in a controlled environment. The changes were investigated by a new analytical approach by combining traditional techniques such as reflectance spectrophotometry in the visible range and Fourier transform infrared spectroscopy with new hyperspectral imaging, in order to obtain forecast models to describe the phenomenon. The statistical elaboration of the experimental data allowed to validate the measurements and to obtain models enabling to relate the investigated parameters; the elaboration of the hyperspectral images by chemometric methods allowed for studying the changes in the reflectance spectra. A result of great importance is the possibility to correlate the oxidation of wood chemical components with the colour change in a totally non-invasive modality. This result is particularly relevant in the field of cultural heritage and in general in the control processes of wooden materials.

  9. Development of synchrotron x-ray micro-spectroscopic techniques and application to problems in low temperature geochemistry. Progress report

    SciTech Connect

    Not Available

    1993-10-01

    The focus of the technical development effort has been the development of apparatus and techniques for the utilization of X-ray Fluorescence (XRF), Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) spectroscopies in a microprobe mode. The present XRM uses white synchrotron radiation (3 to 30 keV) from a bending magnet for trace element analyses using the x-ray fluorescence technique Two significant improvements to this device have been recently implemented. Focusing Mirror: An 8:1 ellipsoidal mirror was installed in the X26A beamline to focus the incident synchrotron radiation and thereby increase the flux on the sample by about a factor of 30. Incident Beam Monochromator: The monochromator has been successfully installed and commissioned in the X26A beamline upstream of the mirror to permit analyses with focused monochromatic radiation. The monochromator consists of a channel-cut silicon (111) crystal driven by a Klinger stepping motor translator. We have demonstrated the operating range of this instrument is 4 and 20 keV with 0.01 eV steps and produces a beam with a {approximately}10{sup {minus}4} energy bandwidth. The primary purpose of the monochromator is for x-ray absorption spectroscopy (XAS) measurements but it is also used for selective excitation in trace element microanalysis. To date, we have conducted XANES studies on Ti, Cr, Fe, Ce and U, spanning the entire accessible energy range and including both K and L edge spectra. Practical detection limits for microXANES are 10--100 ppM for 100 {mu}m spots.

  10. Precise oxygen and hydrogen isotope determination in nanoliter quantities of speleothem inclusion water by cavity ring-down spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Uemura, Ryu; Nakamoto, Masashi; Asami, Ryuji; Mishima, Satoru; Gibo, Masakazu; Masaka, Kosuke; Jin-Ping, Chen; Wu, Chung-Che; Chang, Yu-Wei; Shen, Chuan-Chou

    2016-01-01

    Speleothem inclusion-water isotope compositions are a promising new climatic proxy, but their applicability is limited by their low content in water and by analytical challenges. We have developed a precise and accurate isotopic technique that is based on cavity ring-down spectroscopy (CRDS). This method features a newly developed crushing apparatus, a refined sample extraction line, careful evaluation of the water/carbonate adsorption effect. After crushing chipped speleothem in a newly-developed crushing device, released inclusion water is purified and mixed with a limited amount of nitrogen gas in the extraction line for CRDS measurement. We have measured 50-260 nL of inclusion water from 77 to 286 mg of stalagmite deposits sampled from Gyokusen Cave, Okinawa Island, Japan. The small sample size requirement demonstrates that our analytical technique can offer high-resolution inclusion water-based paleoclimate reconstructions. The 1σ reproducibility for different stalagmites ranges from ±0.05 to 0.61‰ for δ18O and ±0.0 to 2.9‰ for δD. The δD vs. δ18O plot for inclusion water from modern stalagmites is consistent with the local meteoric water line. The 1000 ln α values based on calcite and fluid inclusion measurements from decades-old stalagmites are in agreement with the data from present-day farmed calcite experiment. Combination of coeval carbonate and fluid inclusion data suggests that past temperatures at 9-10 thousand years ago (ka) and 26 ka were 3.4 ± 0.7 °C and 8.2 ± 2.4 °C colder than at present, respectively.

  11. Spin superfluidity and coherent spin precession

    NASA Astrophysics Data System (ADS)

    Bunkov, Yuriy M.

    2009-04-01

    The spontaneous phase coherent precession of the magnetization in superfluid 3He-B was discovered experimentally in 1984 at the Institute for Physical Problems, Moscow by Borovik-Romanov, Bunkov, Dmitriev and Mukharsky and simultaneously explained theoretically by Fomin (Institut Landau, Moscow). Its formation is a direct manifestation of spin superfluidity. The latter is the magnetic counterpart of mass superfluidity and superconductivity. It is also an example of the Bose-Einstein condensation of spin-wave excitations (magnons). The coherent spin precession opened the way for investigations of spin supercurrent magnetization transport and other related phenomena, such as spin-current Josephson effect, process of phase slippage at a critical value of spin supercurrent, spin-current vortices, non-topological solitons (analogous to Q-balls in high energy physics) etc. New measuring techniques based on coherent spin precession made the investigation of mass counterflow and mass vortices possible owing to the spin-mass interaction. New phenomena were observed: mass-spin vortices, the Goldstone mode of the mass vortex with non-axisymmetric core, superfluid density anisotropy etc. Different types of coherent spin precession were later found in superfluid 3He-A and 3He-B confined in anisotropic aerogel, in the states with counterflow and in 3He with reduced magnetization. Finally, spin superfluidity investigations developed the basis for a modern investigation of electron spin supercurrent and spintronics.

  12. J-Modulation in ID NMR 1H Spectrum of Taurine and Aspartate Using Spin-Echo Technique

    NASA Astrophysics Data System (ADS)

    Oturak, Halil; Sağlam, Adnan; Bahçeli, Semiha

    1999-05-01

    This study reports on a theoretical calculation of Hahn's spin-echo experiment in case of a model A2B2 spin system with a strongly coupling character and gives the experimental results of one-dimension 1H high-resolution NMR spectra of taurine and aspartate. The calculated amplitudes of the spin-echoes for two different proton groups of taurine are given. Using results of our calculations for taurine, the computer simulations of J-modulation are implemented. It is shown that the agreement be-tween the experimental and simulated spectra is good.

  13. High-Spin Cobalt Hydrides for Catalysis

    SciTech Connect

    Holland, Patrick L.

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  14. Astronomy: A new spin on exoplanets

    NASA Astrophysics Data System (ADS)

    Barman, Travis

    2014-05-01

    Spectroscopic observations of a young exoplanet have allowed its spin velocity to be directly measured. Its fast spin is in accord with the extrapolation of the known trend in spin velocity as a function of planet mass. See Letter p.63

  15. Use of radiocarbon and spectroscopic analyses to characterise soil organic matter pools isolated using different fractionation techniques.

    NASA Astrophysics Data System (ADS)

    Miller, Gemma; Cloy, Joanna; Garnett, Mark; Sohi, Saran; Rees, Robert; Griffiths, Bryan

    2015-04-01

    Experimental division of soil organic matter (SOM) into functional pools has the potential to improve soil C modelling. Soil physical fractionation techniques seek to quantify these pools, however the fractions isolated vary in number, size, ecological role and composition. The use of different techniques to quantify soil C fractions in different studies presents a question - do similar fractions isolated by different methods fit the same conceptual definition? This study examined a sandy loam from the south-west of Scotland, sampled in summer, which had been under grassland management for at least 20 years. We compared average 14C ages of SOM fractions isolated using three published and frequently applied physical fractionation methods (1) a density separation technique isolating three fractions - free light (FLF) < 1.8 cm 3, intra-aggregate light (IALF) < 1.8 cm-3 after aggregate disruption, and organo-mineral (O-min) > 1.8 g cm 3 (Sohi et al, 2001); (2) a combined physical and chemical separation isolating five fractions: sand and aggregates (S+A) > 63 µm and > 1.8 g cm-3, particulate organic matter (POM) > 63 µm and < 1.8 g cm 3, silt and clay (s+c) < 63 but > 45 µm, residual organic carbon (rSOC) the residue left after s+c is oxidised with NaOCl, and dissolved organic carbon (DOC) < 45 µm (Zimmermann et al, 2007); and (3) a hot water extraction method isolating two fractions: water soluble C (WSC) at 20 °C and hot water extractable C (HWEC) at 80 °C (Ghani et al, 2003). The fractions from Method 1 had the most distinct average 14C ages with O-min, FLF and IALF assessed as 206, 1965 and 6172 years before present (BP) respectively. The fractions from Method 2 fell into two age groups, < ~1000 years BP for s+c, rSOC and S+A and > 4000 years BP for DOC and POM. Both Method 3 fractions were dominated by modern C. The average 14C ages of FLF, IALF, DOC and POM were surprisingly higher than the mineral bound fractions, although they made up a relatively small

  16. Diatomic interhalogens - Systematics and implications of spectroscopic interatomic potentials and curve crossings

    NASA Technical Reports Server (NTRS)

    Child, M. S.; Bernstein, R. B.

    1973-01-01

    Spectroscopically derived potential curves for the low-lying excited states of homonuclear and heteronuclear diatomic interhalogens are systematized by the spin-orbit state of their dissociation products. The implications of spectroscopic interatomic potentials and curve crossings are discussed.

  17. Diatomic interhalogens - Systematics and implications of spectroscopic interatomic potentials and curve crossings

    NASA Technical Reports Server (NTRS)

    Child, M. S.; Bernstein, R. B.

    1973-01-01

    Spectroscopically derived potential curves for the low-lying excited states of homonuclear and heteronuclear diatomic interhalogens are systematized by the spin-orbit state of their dissociation products. The implications of spectroscopic interatomic potentials and curve crossings are discussed.

  18. Using terahertz time-domain spectroscopical technique to monitor cocrystal formation between piracetam and 2,5-dihydroxybenzoic acid

    NASA Astrophysics Data System (ADS)

    Du, Yong; Xia, Yi; Zhang, Huili; Hong, Zhi

    2013-07-01

    Far-infrared vibrational absorption of cocrystal formation between 2,5-dihydroxybenzoic acid (2,5-DHBA) and piracetam compounds under solvent evaporation and grinding methods have been investigated using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The experimental results show large difference among absorption spectra of the formed cocrystals and the involved individual parent molecules in 0.20-1.50 THz region, which probably originated from the intra-molecular and inter-molecular hydrogen bonds due to the presence of two hydroxyl groups in 2,5-DHBA and amide moieties in piracetam compound. The THz absorption spectra of two formed cocrystals with different methods are almost identical. With grinding method, the reaction process can be monitored directly from both time-domain and frequency-domain spectra using THz-TDS technique. The results indicate that THz-TDS technology can absolutely offer us a high potential method to identify and characterize the formed cocrystals, and also provide the rich information about their reaction dynamic process involving two or more molecular crystals in situ to better know the corresponding reaction mechanism in pharmaceutical fields.

  19. Using terahertz time-domain spectroscopical technique to monitor cocrystal formation between piracetam and 2,5-dihydroxybenzoic acid.

    PubMed

    Du, Yong; Xia, Yi; Zhang, Huili; Hong, Zhi

    2013-07-01

    Far-infrared vibrational absorption of cocrystal formation between 2,5-dihydroxybenzoic acid (2,5-DHBA) and piracetam compounds under solvent evaporation and grinding methods have been investigated using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The experimental results show large difference among absorption spectra of the formed cocrystals and the involved individual parent molecules in 0.20-1.50 THz region, which probably originated from the intra-molecular and inter-molecular hydrogen bonds due to the presence of two hydroxyl groups in 2,5-DHBA and amide moieties in piracetam compound. The THz absorption spectra of two formed cocrystals with different methods are almost identical. With grinding method, the reaction process can be monitored directly from both time-domain and frequency-domain spectra using THz-TDS technique. The results indicate that THz-TDS technology can absolutely offer us a high potential method to identify and characterize the formed cocrystals, and also provide the rich information about their reaction dynamic process involving two or more molecular crystals in situ to better know the corresponding reaction mechanism in pharmaceutical fields. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. [IR/UV spectroscopic analysis of gangliosides and their microstructures of polymeric aggregates observed by AFM technique].

    PubMed

    Wang, Hai-long; Sun, Run-guang; Zhang, Jing; Hao, Chang-chun

    2009-04-01

    Gangliosides, a kind of acid glycosphingolipid containing sialic acid, plays a very important physiological role in biomembrane as one of the important components of neurocyte membrane. They were extracted from bovine brain by the Folch method and purified by silica gel and DEAE-Sephadex A-25 column chromatograph. Their molecular functional groups and microstructures of polymeric aggregates were studied by infrared spectrum (IR), ultraviolet spectrum (UV) and atomic force microscope (AFM). The experimental results indicate that: 55.2 mg of Gls from 100 g of wet bovine brain had a certain purity, 62.84%. And their UV absorption spectra appeared at 195 nm, near to the results reported by other peoples. Compared with the IR spectra of sialic acid, the experimental results showed that the structures of the products had the units of sialic acid. In order to investigate the aggregate structures of ganglioside. AFM technique was applied in water, and the results showed that gangliosides can form spherical or ellipsoidal structures in water. It was determined that the size of polymeric aggregates of gangliosides varies between 55 and 380 nm, the average size is (148.9+/-66.7) nm; the height is between 1.0 and 5.0 nm, and the average height is (3.25+/-1.01) nm. The experimental results provide a theoretical and experimental basis for investigating biological activity and the exploitation and utilization of neural drugs.

  1. X-ray spectroscopic technique for energetic electron transport studies in short-pulse laser/plasma interactions

    SciTech Connect

    Tutt, T.E.

    1994-12-01

    When a solid target is irradiated by a laser beam, the material is locally heated to a high temperature and a plasma forms. The interaction of the laser with plasma can produce energetic electrons. By observing the behavior of these {open_quotes}hot{close_quotes} electrons, we hope to obtain a better understanding of Laser/Plasma Interactions. In this work we employ a layered-fluorescer technique to study the transport, and therefore the energetics, of the electrons. The plasma forms on a thin foil of metallic Pd which is bonded to thin layer of metallic Sn. Electrons formed from the plasma penetrate first the Pd and then the Sn. In both layers the energetic electrons promote inner (K) shell ionization of the metallic atoms which leads to the emission of characteristic K{sub {alpha}} x-rays of the fluorescers. By recording the x-ray spectrum emitted by the two foils, we can estimate the energy-dependent range of the electrons and their numbers.

  2. Study on the interaction of the epilepsy drug, zonisamide with human serum albumin (HSA) by spectroscopic and molecular docking techniques

    NASA Astrophysics Data System (ADS)

    Shahabadi, Nahid; Khorshidi, Aref; Moghadam, Neda Hossinpour

    2013-10-01

    In the present investigation, an attempt has been made to study the interaction of zonisamide (ZNS) with the transport protein, human serum albumin (HSA) employing UV-Vis, fluorometric, circular dichroism (CD) and molecular docking techniques. The results indicated that binding of ZNS to HSA caused strong fluorescence quenching of HSA through static quenching mechanism, hydrogen bonds and van der Waals contacts are the major forces in the stability of protein ZNS complex and the process of the binding of ZNS with HSA was driven by enthalpy (ΔH = -193.442 kJ mol-1). The results of CD and UV-Vis spectroscopy showed that the binding of this drug to HSA induced conformational changes in HSA. Furthermore, the study of molecular docking also indicated that zonisamide could strongly bind to the site I (subdomain IIA) of HSA mainly by hydrophobic interaction and there were hydrogen bond interactions between this drug and HSA, also known as the warfarin binding site.

  3. Binding studies of the anti-retroviral drug, efavirenz to calf thymus DNA using spectroscopic and voltammetric techniques.

    PubMed

    Sadeghi, Marzieh; Bayat, Maryam; Cheraghi, Shekofeh; Yari, Khirollah; Heydari, Rouhollah; Dehdashtian, Sara; Shamsipur, Mojtaba

    2016-02-01

    Interactions between efavirenz (EFZ) with calf thymus DNA (CT-DNA) were investigated in vitro under stimulated physiological conditions using multispectroscopic techniques, cyclic voltammetry viscosity measurement, and gel electrophoresis. Methylene blue and acridine orange dyes were used as spectral probes by fluorescence spectroscopy. Hypochromicity was observed in ultra-violet (UV) absorption band of EFZ. Considerable fluorescence enhancement of EFZ was observed in the presence of increasing amounts of DNA solution and the binding constants (Kf ) and corresponding numbers of binding sites (n) were calculated at different temperatures. Thermodynamic parameters including enthalpy change (ΔH) and entropy change (ΔS) were calculated to be -304.78 kJ mol(-1) and -924.52 J mol(-1)  K(-1) according to the van 't Hoff equation, which indicated that reaction is predominantly enthalpically driven. In addition, UV/vis absorption titration of DNA bases confirmed that EFZ interacted with guanine and cytosine preferentially. Gel electrophoresis of DNA with EFZ demonstrated that EFZ also has the ability to cleave supercoiled plasmid DNA. Circular dichroism study showed stabilization of the right-handed B form of CT-DNA. All results suggest that EFZ interacts with CT-DNA via an intercalative mode of binding. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Insights from spectroscopic and in-silico techniques for the exploitation of biomolecular interactions between Human serum albumin and Paromomycin.

    PubMed

    Raza, Muslim; Jiang, Yang; Wei, Yun; Ahmad, Aftab; Khan, Ajmal; Qipeng, Yuan

    2017-09-01

    The study of molecular interactions of drug-protein are extremely important from the biological aspect in all living organisms, and therefore such type of investigation hold a tremendous significance in rational drug design and discovery. In the present study, the molecular interactions between paromomycin (PAR) and human serum albumin (HSA) have been studied by different biophysical techniques and validated by in-silico approaches. The results obtained from Ultraviolet-visible spectroscopy (UV) and Fourier transform infrared spectroscopy (FT-IR) demonstrated a remarkable change upon the complexation of PAR with HSA. Circular Dichroism (CD), Dynamic Light Scattering (DLS) and Resonance Rayleigh scattering (RRS) results revealed a significant secondary structure alteration and reduction of hydrodynamic radii upon the conjugation of PAR with HSA. The fluorescence spectroscopy results also apparently revealed the static quenching mechanism. The number of binding sites, binding constants, and Gibbs free energy values were calculated to illustrate the nature of intermolecular interactions. Similarly, the in-silico docking and molecular dynamics simulation clearly explain the theoretical basis of the binding mechanism of PAR with HSA. The experimental and docking approaches suggested that PAR binds to the hydrophobic cavity site I of HSA. The finding of present investigation will provide binding insight of PAR and associated alterations in the stability and conformation of HSA. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Mass and Spin Measurement Techniques (for the Large Hadron Collider):. Lectures Given at TASI 2011, Boulder, Colorado

    NASA Astrophysics Data System (ADS)

    Lester, Christopher G.

    2013-12-01

    For TASI 2011, I was asked to give a series of lectures on "Mass and Spin Measurement Techniques" with relevance to the Large Hadron Collider. This document provides a written record of those lectures - or more precisely of what I said while giving the lectures - warts and all. It is provided as my contribution to the proceedings primarily for the benefit of those who heard the lectures first hand and may wish to refer back to them. What it is not is a scientific paper or a teaching resource. Though lecture slides may be prepared in advance, what is actually said in a lecture is usually extemporaneous, may be partial, can be influenced by audience reaction, and may not even make sense without a visual record of the concomitant gesticulations of the lecturer. More worryingly, some of the statements made may be down-right false, if the lecturer's tongue is in a twist. Accordingly, these proceedings are provided without warranty of any kind - not least in respect of accuracy or impartiality. The lectures were intended to engage the audience and get them thinking about a number of topics that they had not seen before. They were not expected to be the sort of sombre or well-balanced overview of the field that one might hope to achive in a review. These proceedings are provided to jog the memory of those who saw the lectures first hand, and for little other purpose. Footnotes, where they appear, indicate text/thoughts I have added during the editing process that were not voiced during the lectures themselves. Copies of the lecture slides are inserted at approximately the locations they would have become visible in the lectures.

  6. Vibrational 13C-cross-polarization/magic angle spinning NMR spectroscopic and thermal characterization of poly(alanine-glycine) as model for silk I Bombyx mori fibroin.

    PubMed

    Monti, Patrizia; Taddei, Paola; Freddi, Giuliano; Ohgo, Kosuke; Asakura, Tetsuo

    2003-01-01

    This study focuses on the conformational characterization of poly(alanine-glycine) II (pAG II) as a model for a Bombyx mori fibroin silk I structure. Raman, IR, and 13C-cross-polarization/magic angle spinning NMR spectra of pAG II are discussed in comparison with those of the crystalline fraction of B. mori silk fibroin (chymotryptic precipitate, Cp) with a silk I (silk I-Cp) structure. The spectral data give evidence that silk I-Cp and the synthetic copolypeptide pAG II have similar conformations. Moreover, the spectral findings reveal that silk I-Cp is more crystalline than pAG II; consequently, the latter contains a larger amount of the random coil conformation. Differential scanning calorimetry measurements confirm this result. N-Deuteration experiments on pAG II allow us to attribute the Raman component at 1320 cm(-1) to the amide III mode of a beta-turn type II conformation, thus confirming the results of those who propose a repeated beta-turn type II structure for silk I. The analysis of the Raman spectra in the nuNH region confirms that the silk I structure is characterized by the presence of different types of H-bonding arrangements, in agreement with the above model. Copyright 2003 Wiley Periodicals, Inc.

  7. An assessment of contemporary atomic spectroscopic techniques for the determination of lead in blood and urine matrices

    NASA Astrophysics Data System (ADS)

    Parsons, Patrick J.; Geraghty, Ciaran; Verostek, Mary Frances

    2001-09-01

    The preparation and validation of a number of clinical reference materials for the determination of lead in blood and urine is described. Four candidate blood lead reference materials (Lots, 047-050), and four candidate urine lead reference materials (Lots, 034, 035, 037 and 038), containing physiologically-bound lead at clinically relevant concentrations, were circulated to up to 21 selected laboratories specializing in this analysis. Results from two interlaboratory studies were used to establish certified values and uncertainty estimates for these reference materials. These data also provided an assessment of current laboratory techniques for the measurement of lead in blood and urine. For the blood lead measurements, four laboratories used electrothermal atomization AAS, three used anodic stripping voltammetry and one used both ETAAS and ICP-MS. For the urine lead measurements, 11 laboratories used ETAAS (most with Zeeman background correction) and 10 used ICP-MS. Certified blood lead concentrations, ±S.D., ranged from 5.9±0.4 μg/dl (0.28±0.02 μmol/l) to 76.0±2.2 μg/dl (3.67±0.11 μmol/l) and urine lead concentrations ranged from 98±5 μg/l (0.47±0.02 μmol/l) to 641±36 μg/l (3.09±0.17 μmol/l). The highest concentration blood lead material was subjected to multiple analyses using ETAAS over an extended time period. The data indicate that more stringent internal quality control practices are necessary to improve long-term precision. While the certification of blood lead materials was accomplished in a manner consistent with established practices, the urine lead materials proved more troublesome, particularly at concentrations above 600 μg/l (2.90 μmol/l).

  8. Studying Iron Mineralogy to Understand Redox Conditions in the Mesoproterozoic Belt Basin, USA Using Complementary Microscopic, Spectroscopic, and Magnetic Techniques

    NASA Astrophysics Data System (ADS)

    Slotznick, S. P.; Webb, S.; Kirschvink, J. L.; Fischer, W. W.

    2015-12-01

    Observations of iron chemistry and mineralogy over time provide a valuable tool for studying paleoenvironments, but questions still remain as to the redox character of Proterozoic basins after the rise of oxygen. To evaluate the mechanisms of iron mineralization in Proterozoic samples, we developed an approach that pairs the microscale textural techniques of light microscopy, magnetic scanning microscopy, and (synchrotron-based) microprobe x-ray spectroscopy with sensitive bulk rock magnetic experiments. Samples were collected from stratigraphic sections across the ~1.4 Ga lower Belt Group, Belt Supergroup, MT and ID, USA with a focus on excellently preserved sedimentary rocks, but also including those altered by a variety of diagenetic, metamorphic, and metasomatic events. Results show that even in the best-preserved parts of the Belt Basin, late diagenetic and/or metasomatic fluids affected (in some cases very mildly) the primary iron phases as evidenced by prevalent post-depositional alterations such as rare base metal sulfides. In more heavily altered rocks, the appearance of pyrrhotite and other minerals signaled transformations in iron mineralogy through metamorphism and metasomatism. Despite these secondary phases crystallizing in an open fluid-rich system, primary records of redox chemistry were preserved in the recrystallized early diagenetic framboidal pyrite and (sub)micron-sized detrital magnetite grains. Detrital magnetite is not the most abundant iron-bearing phase in any of the samples (typically <0.01 wt%), but is widely observed in both proximal and deeper basin facies, illustrating an important detrital flux of iron to the basin and a highly reactive iron source for early diagenetic pyrite. Based on our analyses, we interpret the shallow waters of the Belt Basin to be oxic with sulfidic pore fluids and deeper waters in parts of the basin as likely euxinic, consistent with the results of some bulk geochemical proxies. This redox reconstruction also

  9. Studies on the interaction between promethazine and human serum albumin in the presence of flavonoids by spectroscopic and molecular modeling techniques.

    PubMed

    He, Ling-Ling; Wang, Zhi-Xin; Wang, Yong-Xia; Liu, Xian-Ping; Yang, Yan-Jie; Gao, Yan-Ping; Wang, Xin; Liu, Bin; Wang, Xin

    2016-09-01

    Fluorescence, absorption, time-correlated single photon counting (TCSPC), and circular dichroism (CD) spectroscopic techniques as well as molecular modeling methods were used to study the binding characterization of promethazine (PMT) to human serum albumin (HSA) and the influence of flavonoids, rutin and baicalin, on their affinity. The results indicated that the fluorescence quenching mechanism of HSA by PMT is a static quenching due to the formation of complex. The reaction was spontaneous and mainly mediated by hydrogen bonds and hydrophobic interactions. The binding distance between the tryptophan residue of HSA and PMT is less than 8nm, which indicated that the energy transfer from the tryptophan residue of HSA to PMT occurred. The binding site of PMT on HSA was located in sites I and the presence of PMT can cause the conformational changes of HSA. There was the competitive binding to HSA between PMT and flavonoids because of the overlap of binding sites in HSA. The flavonoids could decrease the association constant and increase the binding distance. In addition, their synergistic effect can further change the conformation of HSA. The decrease in the affinities of PMT binding to HSA in the presence of flavonoids may lead to the increase of free drug in blood, which would affect the transportation or disposition of drug and evoke an adverse or toxic effect. Hence, rationalising dosage and diet regimens should be taken into account in clinical application of PMT.

  10. Binding site identification of metformin to human serum albumin and glycated human serum albumin by spectroscopic and molecular modeling techniques: a comparison study.

    PubMed

    Rahnama, Elaheh; Mahmoodian-Moghaddam, Maryam; Khorsand-Ahmadi, Sabra; Saberi, Mohammad Reza; Chamani, Jamshidkhan

    2015-01-01

    The interaction between metformin and human serum albumin (HSA), as well as its glycated form (gHSA) was investigated by multiple spectroscopic techniques, zeta potential, and molecular modeling under physiological conditions. The steady state and time-resolved fluorescence data displayed the quenching mechanism of HSA-metformin and gHSA-metformin was static. The binding information, including the binding constants, number of binding sites, effective quenching constant showed that the binding affinity of metformin to HSA was greater than to gHSA which also confirmed by anisotropy measurements. It was determined that metformin had two and one set of binding sites on HSA and gHSA, respectively. Far-UV CD spectra of proteins demonstrated that the α-helical content decreased with increasing metformin concentration. The zeta potential and resonance light scattering (RLS) diagrams provided that lower drug concentration induced metformin aggregation on gHSA surface as compare to HSA. The increase in polarizability was one of the important factors for the enhancement of RLS and the formation of drug/protein complexes. The zeta potential results suggested that both hydrophobic and electrostatic interactions played important roles in the protein-metformin complex formation. Site marker experiments and molecular modeling showed that the metformin bound to subdomain IIIA (Sudlow's site II) on HSA and gHSA.

  11. Structure and spectroscopic analysis of the graphene monolayer film directly grown on the quartz substrate via the HF-CVD technique

    NASA Astrophysics Data System (ADS)

    Mahmoud, Waleed E.; Al-Hazmi, Farag S.; Al-Ghamdi, A. A.; Shokr, F. S.; Beall, Gary W.; Bronstein, Lyudmila M.

    2016-08-01

    Direct growth of a monolayer graphene film on a quartz substrate by a hot filament chemical vapor deposition technique is reported. The monolayer graphene film prepared was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), selected area electron diffraction (SAED), and atomic force microscopy (AFM). The optical properties were studied by spectroscopic elliposmetry. The experimental data were fitted by the Forouhi-Bloomer model to estimate the extinction coefficient and the refractive index of the monolayer graphene film. The refractive index spectrum in the visible region was studied based on the harmonic oscillator model. The lattice dielectric constant, real and imaginary dielectric constants and the ratio of the charge carrier number to the effective mass were determined. The surface and volume energy loss parameters were also found and showed that the value of the surface energy loss is greater than the volume energy loss. The determination of these optical constants will open new avenue for novel applications of graphene films in the field of wave plates, light modulators, ultrahigh-frequency signal processing and LCDs.

  12. Comparison of Y2O3:Bi3+ phosphor thin films fabricated by the spin coating and radio frequency magnetron techniques

    NASA Astrophysics Data System (ADS)

    Jafer, R. M.; Yousif, A.; Kumar, Vinod; Pathak, Trilok Kumar; Purohit, L. P.; Swart, H. C.; Coetsee, E.

    2016-09-01

    The reactive radio-frequency (RF) magnetron sputtering and spin coating fabrication techniques were used to fabricate Y2-xO3:Bix=0.5% phosphor thin films. The two techniques were analysed and compared as part of investigations being done on the application of down-conversion materials for a Si solar cell. The morphology, structural and optical properties of these thin films were investigated. The X-ray diffraction results of the thin films fabricated by both techniques showed cubic structures with different space groups. The optical properties showed different results because the Bi3+ ion is very sensitive towards its environment. The luminescence results for the thin film fabricated by the spin coating technique is very similar to the luminescence observed in the powder form. It showed three obvious emission bands in the blue and green regions centered at about 360, 410 and 495 nm. These emissions were related to the 3P1-1S0 transition of the Bi3+ ion situated in the two different sites of the Y2O3 matrix with I a-3(206) space group. Whereas the thin film fabricated by the radio frequency magnetron technique showed a broad single emission band in the blue region centered at about 416 nm. This was assigned to the 3P1-1S0 transition of the Bi3+ ion situated in one of the Y2O3 matrix's sites with a Fm-3 (225) space group. The spin coating fabrication technique is suggested to be the best technique to fabricate the Y2O3:Bi3+ phosphor thin films.

  13. Differentiation of Salmonella enterica serovars and strains in cultures and food using infrared spectroscopic and microspectroscopic techniques combined with soft independent modeling of class analogy pattern recognition analysis.

    PubMed

    Männig, Annegret; Baldauf, Nathan A; Rodriguez-Romo, Luis A; Yousef, Ahmed E; Rodríguez-Saona, Luis E

    2008-11-01

    Detection of pathogenic microorganisms in food is often a tedious and time-consuming exercise. Developing rapid and cost-effective techniques for identifying pathogens to subspecies is critical for tracking causes of foodborne disease outbreaks. The objective of this study was to develop a method for rapid identification and differentiation of Salmonella serovars and strains within these serovars through isolation on hydrophobic grid membrane filters (HGMFs), examination by infrared (IR) spectroscopy and microspectroscopy, and data analysis by multivariate statistical techniques. Salmonella serovars (Anatum, Enteritidis, Heidelberg, Kentucky, Muenchen, and Typhimurium), most of which were represented by multiple strains, were grown in tryptic soy broth (24 h at 42 degrees C), diluted to 10(2) to 10(3) CFU/ml, and filtered using HGMFs. The membranes were incubated on Miller-Mallinson agar (24 h at 42 degrees C), and typical Salmonella colonies were sonicated in 50% acetonitrile and centrifuged. Resulting pellets were vacuum dried on a ZnSe crystal and analyzed using IR spectroscopy. Alternatively, the membranes containing Salmonella growth were removed from the agar, vacuum dried, and colonies were analyzed directly by IR microspectroscopy. Soft independent modeling of class analogy (SIMCA) models were developed from spectra. The method was validated by analyzing Salmonella-inoculated tomato juice, eggs, milk, and chicken. Salmonella serovars exhibited distinctive and reproducible spectra in the fingerprint region (1,200 to 900 cm(-1)) of the IR spectrum. SIMCA permitted distinguishing Salmonella strains from each other through differences in bacterial lipopolysaccharides and other membrane components. The model correctly predicted Salmonella in foods at serovar (100%) and strain (90%) levels. Isolation of Salmonella on HGMF and selective agar followed by IR spectroscopic analysis resulted in rapid and efficient isolation, identification, and differentiation of

  14. Nickel complexes of o-amidochalcogenophenolate(2-)/o-iminochalcogenobenzosemiquinonate(1-) pi-radical: synthesis, structures, electron spin resonance, and x-ray absorption spectroscopic evidence.

    PubMed

    Hsieh, Chung-Hung; Hsu, I-Jui; Lee, Chien-Ming; Ke, Shyue-Chu; Wang, Tze-Yuan; Lee, Gene-Hsiang; Wang, Yu; Chen, Jin-Ming; Lee, Jyh-Fu; Liaw, Wen-Feng

    2003-06-16

    The preparation of complexes trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) (1), cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) (2), trans-[Ni(-SC(6)H(4)-o-NH-)(2)](-) (3), and [Ni(-SC(6)H(4)-o-S-)(2)](-) (4) by oxidative addition of 2-aminophenyl dichalcogenides to anionic [Ni(CO)(SePh)(3)](-) proves to be a successful approach in this direction. The cis arrangement of the two tellurium atoms in complex 2 is attributed to the intramolecular Te.Te contact interaction (Te.Te contact distance of 3.455 A). The UV-vis electronic spectra of complexes 1 and 2 exhibit an intense absorption at 936 and 942 nm, respectively, with extinction coefficient epsilon > 10000 L mol(-)(1) cm(-)(1). The observed small g anisotropy, the principal g values at g(1) = 2.036, g(2) = 2.062, and g(3) = 2.120 for 1 and g(1) = 2.021, g(2) = 2.119, and g(3) = 2.250 for 2, respectively, indicates the ligand radical character accompanied by the contribution of the singly occupied d orbital of Ni(III). The X-ray absorption spectra of all four complexes show L(III) peaks at approximately 854.5 and approximately 853.5 eV. This may indicate a variation of contribution of the Ni(II)-Ni(III) valence state. According to the DFT calculation, the unpaired electron of complex 1 and 2 is mainly distributed on the 3d(xz)() orbital of the nickel ion and on the 4p(z)() orbital of selenium (tellurium, 5p(z)()) as well as the 2p(z)() orbital of nitrogen of the ligand. On the basis of X-ray structural data, UV-vis absorption, electron spin resonance, magnetic properties, DFT computation, and X-ray absorption (K- and L-edge) spectroscopy, the monoanionic trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) and cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) complexes are appositely described as a resonance hybrid form of Ni(III)-bis(o-amidochalcogenophenolato(2-)) and Ni(II)-(o-amidochalcogenophenolato(2-))-(o-iminochalcogenobenzosemiquinonato(1-) pi-radical; i.e., complexes 1 and 2 contain delocalized oxidation levels of the nickel ion and ligands.

  15. Spectroscopic Evidence for Covalent Binding of Sulfadiazine to Natural Soils via 1,4-nucleophilic addition (Michael Type Addition) studied by Spin Labeling ESR

    NASA Astrophysics Data System (ADS)

    Aleksandrova, Olga

    2015-04-01

    Among different classes of veterinary pharmaceuticals, Sulfadiazine (SDZ) is widely used in animal husbandry. Its residues were detected in different environmental compartments. However, soil is a hot spot for SDZ as it receives a large portion of excreted compounds through the application of manure during soil fertilization. Ample studies on the fate of SDZ in soils showed that a large portion forms nonextractable residues (NER) along with transformation products and a low mineralization (Mueller et al., 2013). A common observation was an initially fast formation of NER up to 10% of the applied amount promptly after the application of SDZ to soil, and this portion increased up to 50% within a few days (Mueller et al., 2013; Nowak et al., 2011). A common finding for SDZ, as for other sulfonamides, was biphasic kinetics of the formation of NER, which was attributed to the occurrence of two reaction processes: a rapid, often reversible process and a slower, irreversible process (Weber et al., 1996). A single-phase reaction process was also established under anaerobic treatment (Gulkowska et al., 2014). A major focus of this work is to elucidate a reaction mechanism of covalent binding of SDZ to soil that is currently required to estimate a risk of NER formed by SDZ in soils for human health. Taking into account a key role of the amine functional groups of SDZ on its reactivity in soil, nitroxide radicals with the sewed aromatic or aliphatic amines labeled soil samples and then, were investigated by means of ESR spectroscopy. 2,5,5-Trimethyl-2-(3-aminophenyl)pyrrolidin-1-yloxy and 4-amino-2,2,6,6-Tetramethylpiperidin-1-oxyl modeled decomposition products of SDZ with the aromatic and aliphatic amines, respectively. The application of the defined combination of both spin labels (SL) to different soils well simulated a change of a paramagnetic signal of soil organic radicals interacted with SDZ. After their application to soil, SL were found in soil sites characterized

  16. γ -ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Krtička, M.; Bernstein, L. A.; Allmond, J. M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Daub, B. H.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Larsen, A. C.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.; Volya, A.

    2016-02-01

    The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d ,p ) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p -γ and p -γ -γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p -γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levels with high spins populated in the (d ,p ) reaction above the neutron separation energy. Spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method.

  17. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dutra, Eric C.; Covington, Aaron M.; Darling, Timothy; Mancini, Roberto C.; Haque, Showera; Angermeier, William A.

    2016-09-01

    Visible spectroscopic techniques are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. Experiments conducted at the University of Nevada (Reno) at the Nevada Terawatt Facility (NTF) using the 1 MA Z-pinch (Zebra). The research explored the response of Al III doublet, 4p 2P3/2 to 4s 2S1/2 and 4p 2P1/2 to 4s 2S1/2 transitions. Optical light emitted from the pinch is fiber coupled to high-resolution spectrometers. The dual spectrometers are coupled to two high-speed visible streak cameras to capture time-resolved emission spectra from the experiment. The data reflects emission spectra from 100 ns before the current peak to 100 ns after the current peak, where the current peak is approximately the time at which the pinch occurs. The Al III doublet is used to measure Zeeman, Stark, and Doppler broadened emission. The line emission is then used to calculate the temperature, electron density, and B-fields. The measured quantities are used as initial parameters for the line shape code to simulate emission spectra and compare to experimental results. Future tests are planned to evaluate technique and modeling on other material wire array, gas puff, and DPF platforms. This work was done by National

  18. Use of spectroscopic, zeta potential and molecular dynamic techniques to study the interaction between human holo-transferrin and two antagonist drugs: comparison of binary and ternary systems.

    PubMed

    Kabiri, Mona; Amiri-Tehranizadeh, Zeinab; Baratian, Ali; Saberi, Mohammad Reza; Chamani, Jamshidkhan

    2012-03-12

    For the first time, the binding of ropinirole hydrochloride (ROP) and aspirin (ASA) to human holo-transferrin (hTf) has been investigated by spectroscopic approaches (fluorescence quenching, synchronous fluorescence, time-resolved fluorescence, three-dimensional fluorescence, UV-vis absorption, circular dichroism, resonance light scattering), as well as zeta potential and molecular modeling techniques, under simulated physiological conditions. Fluorescence analysis was used to estimate the effect of the ROP and ASA drugs on the fluorescence of hTf as well as to define the binding and quenching properties of binary and ternary complexes. The synchronized fluorescence and three-dimensional fluorescence spectra demonstrated some micro-environmental and conformational changes around the Trp and Tyr residues with a faint red shift. Thermodynamic analysis displayed the van der Waals forces and hydrogen bonds interactions are the major acting forces in stabilizing the complexes. Steady-state and time-resolved fluorescence data revealed that the fluorescence quenching of complexes are static mechanism. The effect of the drugs aggregating on the hTf resulted in an enhancement of the resonance light scattering (RLS) intensity. The average binding distance between were computed according to the forster non-radiation energy transfer theory. The circular dichroism (CD) spectral examinations indicated that the binding of the drugs induced a conformational change of hTf. Measurements of the zeta potential indicated that the combination of electrostatic and hydrophobic interactions between ROP, ASA and hTf formed micelle-like clusters. The molecular modeling confirmed the experimental results. This study is expected to provide important insight into the interaction of hTf with ROP and ASA to use in various toxicological and therapeutic processes.

  19. Spectroscopic ellipsometry of Zn(1-x)Cu(x)O thin films based on a modified sol-gel dip-coating technique.

    PubMed

    Al-Khanbashi, Hibah A; Shirbeeny, W; Al-Ghamdi, A A; Bronstein, Lyudmila M; Mahmoud, Waleed E

    2014-01-24

    Nanocrystalline Zn(1-x)Cu(x)O thin films (x=0, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by sol-gel dip-coating technique on a quartz substrate. These films were annealed at 350°C for 2 h. The X-ray diffraction showed a hexagonal crystal structure with high intensity peak for the (002) reflection plane indicating preferential growth along the c-axis of the crystal lattice. The peak position related to the (002) peak was shifted as a result of the copper ion incorporation, confirming the interstitial substitution of the zinc ions by the copper ions. This interstitial substitution leads to a decrease of an average crystallite size and lattice constants and an increase of the micro-strain up to 2 at.% of the copper amount. The surface morphology was explored by scanning electron microscopy which confirmed the homogenous distribution of nanoparticles in the deposited films along the quartz substrates. The energy dispersion X-ray spectroscopy revealed absence of impurities in the as-deposited films. The high resolution electron microscopy and selected area electron diffraction depicted that the films have polycrystalline nature. The film thickness and optical constants of the Zn(1-x)Cu(x)O thin films were estimated by fitting the spectroscopic ellipsometric data (ψ and Δ) using three different models. The refractive index was fitted using harmonic oscillator model from which the oscillator and the dispersive energies were found. The dielectric constant, dielectric loss, energy loss functions were also determined.

  20. Spectroscopic ellipsometry of Zn1-xCuxO thin films based on a modified sol-gel dip-coating technique

    NASA Astrophysics Data System (ADS)

    Al-Khanbashi, Hibah A.; Shirbeeny, W.; Al-Ghamdi, A. A.; Bronstein, Lyudmila M.; Mahmoud, Waleed E.

    2014-01-01

    Nanocrystalline Zn1-xCuxO thin films (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by sol-gel dip-coating technique on a quartz substrate. These films were annealed at 350 °C for 2 h. The X-ray diffraction showed a hexagonal crystal structure with high intensity peak for the (0 0 2) reflection plane indicating preferential growth along the c-axis of the crystal lattice. The peak position related to the (0 0 2) peak was shifted as a result of the copper ion incorporation, confirming the interstitial substitution of the zinc ions by the copper ions. This interstitial substitution leads to a decrease of an average crystallite size and lattice constants and an increase of the micro-strain up to 2 at.% of the copper amount. The surface morphology was explored by scanning electron microscopy which confirmed the homogenous distribution of nanoparticles in the deposited films along the quartz substrates. The energy dispersion X-ray spectroscopy revealed absence of impurities in the as-deposited films. The high resolution electron microscopy and selected area electron diffraction depicted that the films have polycrystalline nature. The film thickness and optical constants of the Zn1-xCuxO thin films were estimated by fitting the spectroscopic ellipsometric data (ψ and Δ) using three different models. The refractive index was fitted using harmonic oscillator model from which the oscillator and the dispersive energies were found. The dielectric constant, dielectric loss, energy loss functions were also determined.

  1. Arterial Spin-Labeling Parameters Influence Signal Variability and Estimated Regional Relative Cerebral Blood Flow in Normal Aging and Mild Cognitive Impairment: FAIR versus PICORE Techniques.

    PubMed

    Lövblad, K-O; Montandon, M-L; Viallon, M; Rodriguez, C; Toma, S; Golay, X; Giannakopoulos, P; Haller, S

    2015-07-01

    Arterial spin-labeling is a noninvasive method to map cerebral blood flow, which might be useful for early diagnosis of neurodegenerative diseases. We directly compared 2 arterial spin-labeling techniques in healthy elderly controls and individuals with mild cognitive impairment. This prospective study was approved by the local ethics committee and included 198 consecutive healthy controls (mean age, 73.65 ± 4.02 years) and 43 subjects with mild cognitive impairment (mean age, 73.38 ± 5.85 years). Two pulsed arterial spin-labeling sequences were performed at 3T: proximal inversion with a control for off-resonance effects (PICORE) and flow-sensitive alternating inversion recovery technique (FAIR). Relative cerebral blood flow maps were calculated by using commercial software and standard parameters. Data analysis included spatial normalization of gray matter-corrected relative CBF maps, whole-brain average, and voxelwise comparison of both arterial spin-labeling sequences. Overall, FAIR yielded higher relative CBF values compared with PICORE (controls, 32.7 ± 7.1 versus 30.0 ± 13.1 mL/min/100 g, P = .05; mild cognitive impairment, 29.8 ± 5.4 versus 26.2 ± 8.6 mL/min/100 g, P < .05; all, 32.2 ± 6.8 versus 29.3 ± 12.3 mL/min/100 g, P < .05). FAIR had lower variability (controls, 36.2% versus 68.8%, P < .00001; mild cognitive impairment, 18.9% versus 22.9%, P < .0001; all, 34.4% versus 64.9% P < .00001). The detailed voxelwise analysis revealed a higher signal for FAIR, notably in both convexities, while PICORE had higher signal predominantly in deep cerebral regions. Overall, FAIR had higher estimated relative CBF and lower interindividual variability than PICORE. In more detail, there were regional differences between both arterial spin-labeling sequences. In summary, these results highlight the need to calibrate arterial spin-labeling sequences. © 2015 by American Journal of Neuroradiology.

  2. Diffusion-weighted MRI of the cervical spinal cord using a single-shot fast spin-echo technique: findings in normal subjects and in myelomalacia.

    PubMed

    Tsuchiya, K; Katase, S; Fujikawa, A; Hachiya, J; Kanazawa, H; Yodo, K

    2003-02-01

    We have implemented a new diffusion-weighted MRI (DWI) sequence based on the single-shot fast spin-echo technique. We hypothesised that this would add information to conventional MRI for diagnosis of lesions of the cervical spinal cord. DWI was performed using a technique in which echo collection after the application of motion-probing gradients was done in the same manner as in the single-shot fast spin-echo technique. We first imaged six healthy volunteers to demonstrate the cervical spinal cord using the sequence. Then we applied the sequence to 12 patients with cervical myelomalacia due to chronic cord compression. The spinal cord was well seen in all subjects without the distortion associated with echo-planar DWI. In the patients, lesions appeared as areas of low- or isointense signal on DWI. Calculated apparent diffusion coefficients of the lesions (3.30+/-0.38x10(-3) mm(2)/s) were significantly higher than those of normal volunteers (2.26+/-0.08x10(-3) mm(2)/s). Increased diffusion in areas of cervical myelomalacia, suggesting irreversible damage, can be detected using this technique.

  3. Magic Angle Spinning NMR Spectroscopy: A Versatile Technique for Structural and Dynamic Analysis of Solid-Phase Systems

    PubMed Central

    Polenova, Tatyana; Gupta, Rupal; Goldbourt, Amir

    2016-01-01

    Magic Angle Spinning (MAS) NMR spectroscopy is a powerful method for analysis of a broad range of systems, including inorganic materials, pharmaceuticals, and biomacromolecules. The recent developments in MAS NMR instrumentation and methodologies opened new vistas to atomic-level characterization of a plethora of chemical environments previously inaccessible to analysis, with unprecedented sensitivity and resolution. PMID:25794311

  4. Spins, stripes, and superconductivity in hole-doped cuprates

    NASA Astrophysics Data System (ADS)

    Tranquada, John M.

    2013-08-01

    One of the major themes in correlated electron physics over the last quarter century has been the problem of high-temperature superconductivity in hole-doped copper-oxide compounds. Fundamental to this problem is the competition between antiferromagnetic spin correlations, a symptom of strong Coulomb interactions, and the kinetic energy of the doped carriers, which favors delocalization. After discussing some of the early challenges in the field, I describe the experimental picture provided by a variety of spectroscopic and transport techniques. Then I turn to the technique of neutron scattering, and discuss how it is used to determine spin correlations, especially in model systems of quantum magnetism. Neutron scattering and complementary techniques have determined the extent to which antiferromagnetic spin correlations survive in the cuprate superconductors. One experimental case involves the ordering of spin and charge stripes. I first consider related measurements on model compounds, such as La2-xSrxNiO4+δ, and then discuss the case of La2-xBaxCuO4. In the latter system, recent transport studies have demonstrated that quasi-two-dimensional superconductivity coexists with the stripe order, but with frustrated phase order between the layers. This has led to new concepts for the coexistence of spin order and superconductivity. While the relevance of stripe correlations to high-temperature superconductivity remains a subject of controversy, there is no question that stripes are an intriguing example of electron matter that results from strong correlations.

  5. Thick-Dielectric Formation and MOSFET Reliability with Spin-Coating Film Transfer and Hot-Pressing Technique for Seamless Integration Technology

    NASA Astrophysics Data System (ADS)

    Sato, Norio; Shimoyama, Nobuhiro; Kamei, Toshikazu; Kudou, Kazuhisa; Yano, Masaki; Ishii, Hiromu; Machida, Katsuyuki

    2004-04-01

    The formation of thick dielectrics by the spin-coating film transfer and hot-pressing (STP) technique is proposed for the fabrication of thick multilevel interconnects. Examination of the characteristics of 20-μm-thick dielectrics on 10-μm-thick line-and-space patterns shows sufficient planarization capability with little dependence on pattern density, which enables the fabrication of a double layer of thick interconnects. To investigate the influence of hot pressing in the STP process on LSIs, the hot-carrier degradation of n-channel metal oxide semiconductor field-effect transistors (MOSFETs) was evaluated. The lifetime of transconductance gm of STP samples was estimated to be over ten years, which is the same as that of samples prepared by the conventional technique of spin-coating. Moreover, the lifetime showed no dependence on pressure, temperature in hot pressing and thickness of dielectrics. These results confirm that the STP technique is applicable to the fabrication of thick interconnects and does not damage the underlying MOSFETs.

  6. Gd doping effect on structural, electrical and magnetic properties of ZnO thin films synthesized by sol-gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Thangavel, Rajalingam

    2017-03-01

    Nanocrystalline Gd-doped ZnO thin films were deposited on sapphire (0001) substrates using sol-gel spin coating technique. The structural and optical properties of deposited thin films were characterized by X-ray diffraction (XRD) and micro Raman spectroscopy. Structural and optical studies show that the doped Gd ions occupy Zn sites retaining the wurtzite symmetry. Photoluminescence (PL) studies reveal the presence of oxygen vacancies in Gd doped ZnO thin films. The resistivity of Gd doped ZnO thin film decreases with increase in Gd doping upto 4%. Gd-doped ZnO films demonstrate weak magnetic ordering at room temperature.

  7. Polycrystalline BiFeO{sub 3} thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

    SciTech Connect

    Bogle, K. A. Narwade, R. D.; Mahabole, M. P.; Khairnar, R. S.; Phatangare, A. B.; Dahiwale, S. S.

    2016-05-06

    We are reporting photosensitivity property of BiFeO{sub 3} thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO{sub 3}/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

  8. Search for α-decay of high-spin isomers in rare-earth nuclei using a decay-in-flight technique

    SciTech Connect

    Vrba, Joseph A.

    1980-03-01

    An experimental search has been conducted for α-decay in the lifetime range of from 1 to 100 nsec in a variety of rare earth nuclei produced in reactions of 125 to 146 MeV /sup 16/O ions on targets of /sup 139/La, /sup 141/Pr, and /sup 142/Nd. The products of these reactions include systems in which high spin (I > 10 h-bar) isomeric states have been observed with lifetimes in the range studied. Certain of these isomers may be very high spin statistical yrast traps which have been predicted to occur at spins of from 30 to 50 h-bar in the rare earths. For such spins and lifetimes, calculations suggest that α-decay could be a major mode of de-excitation. The technique employed for these experimental investigations made use of a specially designed trajectory detector to observe α-decay directly from the reaction products which recoiled from a thin target. Analytical procedures developed for reduction of the decay-in-flight data are discussed which yielded information about the particle types detected, the energies of these particles, the trajectories followed, and the positions of parent nuclei at the time the detected particles were emitted. Kinematic and solid angle corrections are considered which permitted correction for Doppler broadening effects and allowed estimates to be made with regard to the lifetime and production cross section of the parent state. The experimental method and the associated analytical procedures were verified by study of α-decay following the reaction /sup 208/Pb(/sup 16/O,p6n)/sup 217/Ac. No system studied in the search for yrast trap α-decay showed activity significantly above background in the 6 to 16 MeV energy range.

  9. Spin foams without spins

    NASA Astrophysics Data System (ADS)

    Hnybida, Jeff

    2016-10-01

    We formulate the spin foam representation of discrete SU(2) gauge theory as a product of vertex amplitudes each of which is the spin network generating function of the boundary graph dual to the vertex. In doing so the sums over spins have been carried out. The boundary data of each n-valent node is explicitly reduced with respect to the local gauge invariance and has a manifest geometrical interpretation as a framed polyhedron of fixed total area. Ultimately, sums over spins are traded for contour integrals over simple poles and recoupling theory is avoided using generating functions.

  10. An in-line micro-pyrolysis system to remove contaminating organic species for precise and accurate water isotope analysis by spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Panetta, R. J.; Hsiao, G.

    2011-12-01

    Trace levels of organic contaminants such as short alcohols and terpenoids have been shown to cause spectral interference in water isotope analysis by spectroscopic techniques. The result is degraded precision and accuracy in both δD and δ18O for samples such as beverages, plant extracts or slightly contaminated waters. An initial approach offered by manufacturers is post-processing software that analyzes spectral features to identify and flag contaminated samples. However, it is impossible for this software to accurately reconstruct the water isotope signature, thus it is primarily a metric for data quality. Here, we describe a novel in-line pyrolysis system (Micro-Pyrolysis Technology, MPT) placed just prior to the inlet of a cavity ring-down spectroscopy (CRDS) analyzer that effectively removes interfering organic molecules without altering the isotope values of the water. Following injection of the water sample, N2 carrier gas passes the sample through a micro-pyrolysis tube heated with multiple high temperature elements in an oxygen-free environment. The temperature is maintained above the thermal decomposition threshold of most organic compounds (≤ 900 oC), but well below that of water (~2000 oC). The main products of the pyrolysis reaction are non-interfering species such as elemental carbon and H2 gas. To test the efficacy and applicability of the system, waters of known isotopic composition were spiked with varying amounts of common interfering alcohols (methanol, ethanol, propanol, hexanol, trans-2-hexenol, cis-3-hexanol up to 5 % v/v) and common soluble plant terpenoids (carveol, linalool, geraniol, prenol). Spiked samples with no treatment to remove the organics show strong interfering absorption peaks that adversely affect the δD and δ18O values. However, with the MPT in place, all interfering absorption peaks are removed and the water absorption spectrum is fully restored. As a consequence, the δD and δ18O values also return to their original

  11. Spectroscopic techniques for assessing the possible use of phosphate rock by-products for the removal of trace elements in soils.

    NASA Astrophysics Data System (ADS)

    Martinez-Sanchez, M. J.; Perez-Sirvent, C.; Garcia-Lorenzo, M. L.; Bech, J.; Hernandez-Cordoba, M.

    2012-04-01

    The production of fertilizers from apatite results in the obtention of considerable amounts of phosphate rock byproducts, representing a serious environmental problem. In addition, soil contamination with heavy metals due to mining or metallurgical activities is a severe environmental problem, increased when soil use is changed to agricultural or urban uses. The aim of this work was to study the possibility of using phosphate rock byproducts for the in situ treatment of soils polluted by heavy metals, allowing to revalorise phosphate rock residues and at the same time, providing a low-cost solution for the contaminated soil. The following methodologies were applied in order to characterise minerals phases present in phosphate rock residues: Wavelength Dispersive X-Ray Spectrometry (WDXRF), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectrometry (EDS), thermogravimetry (TG) and Fourier Transform Infrared Spectroscopy (FTIR). The results obtained showed that the samples studied had a fine texture, showing average contents of 71%, 24% of sand and 5% for silt, sand and clay, respectivaly. In addition, these materials showed basic-neutral pH values (7.5-9) and a cationic interchange capacity of 20.4 meq/100g. Studied samples showed a 22% of carbonates and a 13% of apatite in their composition and all of them showed 4 bands at 1.100, 1.044, 674 y 576 cm-1, corresponding to P-O vibrations in PO4 groups. OH band vibrations appeared at 3.700-3.550 cm-1, and detected band at 3.400 cm-1 and 633 cm-1 could correspond to occluded water. On the other hand, detected bands at 1.460-1.430, 874 cm-1 suggested the presence of CaCO3 and carbonates in the apatite. After sample characterization, the performance of these residues to adsorb trace element ions (Cd+2 and Pb+2) from acidic aqueous solutions (simulating acidic mine drainage) was studied. The use of spectroscopic techniques after mixing soils and phosphate rock products demonstrate that these residues could be

  12. Spectroscopic detection

    DOEpatents

    Woskov, Paul P.; Hadidi, Kamal

    2003-01-01

    In embodiments, spectroscopic monitor monitors modulated light signals to detect low levels of contaminants and other compounds in the presence of background interference. The monitor uses a spectrometer that includes a transmissive modulator capable of causing different frequency ranges to move onto and off of the detector. The different ranges can include those with the desired signal and those selected to subtract background contributions from those with the desired signal. Embodiments of the system are particularly useful for monitoring metal concentrations in combustion effluent.

  13. A laser spectroscopic study of the X~ 2Πg, A~ 2Πu, and B~ 2Σu+ states of BS2: Renner-Teller, spin-orbit, and K-resonance effects

    NASA Astrophysics Data System (ADS)

    He, Sheng-Gui; Clouthier, Dennis J.; Adam, Allan G.; Tokaryk, Dennis W.

    2005-05-01

    The lowest-lying vibronic levels of the X˜,Ã, and B˜ states of BS2 have been investigated at high resolution using a combination of room-temperature absorption and supersonic jet data. In both cases, the BS2 radical was prepared in an electric discharge using a precursor gas mixture of BCl3,CS2, and either helium or argon. Extensive absorption spectra were obtained for the 000 and 211 bands of the ÃΠu2-X˜Πg2 electronic transition in the visible. The ÖX˜211 and B˜Σu +2-X˜Πg2211 bands of jet-cooled BS2 were also studied with laser-induced fluorescence techniques. By fitting the 000 bands of both electronic transitions simultaneously, we were able to precisely determine the spin-orbit splittings in both the à and X˜ states. Similarly, the 211 bands were fitted in a merged analysis in order to determine the relative separations of the vibronic components of the ground and first excited state bending levels as accurately as possible. Due to a large spin-orbit splitting and small Renner-Teller interaction, the à state bending level shows small but definite K-resonance effects, which were fitted using a full matrix for the four components of v2'=1. The resulting parameters were used along with previously published data to refine the Renner-Teller analyses in both the ÃΠu2 and X˜Πg2 electronic states. Where possible, the fitted constants and observed boron isotope splittings have been shown to be in accord with theoretical estimates of their sign and magnitude.

  14. Kinetic effects on double hysteresis in spin crossover molecular magnets analyzed with first order reversal curve diagram technique

    SciTech Connect

    Stan, Raluca-Maria; Gaina, Roxana; Enachescu, Cristian E-mail: radu.tanasa@uaic.ro; Stancu, Alexandru; Tanasa, Radu E-mail: radu.tanasa@uaic.ro; Bronisz, Robert

    2015-05-07

    In this paper, we analyze two types of hysteresis in spin crossover molecular magnets compounds in the framework of the First Order Reversal Curve (FORC) method. The switching between the two stable states in these compounds is accompanied by hysteresis phenomena if the intermolecular interactions are higher than a threshold. We have measured the static thermal hysteresis (TH) and the kinetic light induced thermal hysteresis (LITH) major loops and FORCs for the polycrystalline Fe(II) spin crossover compound [Fe{sub 1−x}Zn{sub x}(bbtr){sub 3}](ClO{sub 4}){sub 2} (bbtr = 1,4-di(1,2,3-triazol-1-yl)butane), either in a pure state (x = 0) or doped with Zn ions (x = 0.33) considering different sweeping rates. Here, we use this method not only to infer the domains distribution but also to disentangle between kinetic and static components of the LITH and to estimate the changes in the intermolecular interactions introduced by dopants. We also determined the qualitative relationship between FORC distributions measured for TH and LITH.

  15. [Shortening of the measurement time by 1H-MR turbo spectroscopic imaging of the brain].

    PubMed

    Träber, F; Block, W; Lamerichs, R; Keller, E; Schild, H H

    1997-03-01

    Development of a new technique for reduction of measurement time in 1H-MR spectroscopic imaging of the brain. Optimisation of the sequence parameters in volunteer and in patient examinations and comparison to the results obtained with conventional 2 D-SI. Examination of 20 healthy volunteers and 5 patients in a 1.5 T whole-body MR system. In "turbo-spectroscopic imaging" (TSI) sequences, a train of spin-echo signals with different phase encoding is acquired after each 90 degrees excitation. 32 x 32 matrix elements covered a field of view of 20 cm, and additional volume selection was performed by double spin echo excitation. Measurement duration 9 min with acquisition of four phase encoding steps per TR interval, whereas the corresponding 2 D-SI sequence (TR/TE 2000/272 ms) took 30 min. The TSI data sets yielded maps of the regional distribution of metabolite concentrations with a quality comparable to the 2 D-SI results. Signal homogeneity and delineation of brain lesions, however, were superior in conventional spectroscopic imaging. The T2 relaxation of the metabolites required a reduced sampling interval for each phase-encoded echo, and hence the frequency resolution of the corresponding TSI spectra was not always sufficient for separating choline and creatine signals. With measurement durations < 10 min the TSI technique allows in clinical studies a combination with single-voxel MRS for accurate quantification and with a diagnostic MRI within a total examination time of less than one hour.

  16. Imaging electrical spin generation and spin Hall dynamics in semiconductors

    NASA Astrophysics Data System (ADS)

    Stern, N. P.

    2009-03-01

    The capability to generate and manipulate spin polarization through the spin-orbit interaction drives interest in all-electrical techniques to exploit electron spins for semiconductor spintronics. The spin Hall effect refers to the generation of a pure spin current transverse to a charge current, resulting in a spontaneous spin accumulation near sample boundaries without the need for magnetic fields or materials. Recent experiments toward imaging this electrically generated spin polarization with both spatially and temporally resolved Kerr rotation microscopy in bulk zincblende semiconductors are discussed. Both current-induced in-plane spin polarization and out-of-plane spin accumulation from the spin Hall effect are observed in ZnSe up to room temperatureootnotetextN. P. Stern, S. Ghosh, G. Xiang, M. Zhu, N. Samarth, and D. D. Awschalom, Phys. Rev. Lett. 97, 126603 (2006). In GaAs devices, spatially resolved measurements of steady-state spin Hall accumulation and associated modeling clarify the important role of drift and diffusion in transporting spins generated at sample boundaries to the device interiorootnotetextN. P. Stern, D. W. Steuerman, S. Mack, A. C. Gossard, and D. D. Awschalom, Appl. Phys. Lett. 91, 062109 (2007). In these typical optical experiments, electrically-generated spin accumulation is measured using steady-state techniques that do not directly observe dynamics at timescales important for device operation. Here we discuss a time- and spatially-resolved measurement of the spin Hall effect using a pulsed current to drive spin accumulationootnotetextN. P. Stern, D. W. Steuerman, S. Mack, A. C. Gossard, and D. D. Awschalom, Nat. Physics 4, 843 (2008). The dynamical processes of spin accumulation and diffusion reveal spatially-dependent nanosecond timescales comparable to the electric-field dependent spin coherence time. A time-dependent diffusion analysis reconciles the observed spatial and temporal dynamics of spin accumulation from the spin

  17. 3D Fast Spin Echo With Out-of-Slab Cancellation: A Technique for High-Resolution Structural Imaging of Trabecular Bone at 7 Tesla

    PubMed Central

    Magland, Jeremy F.; Rajapakse, Chamith S.; Wright, Alexander C.; Acciavatti, Raymond; Wehrli, Felix W.

    2016-01-01

    Spin-echo-based pulse sequences are desirable for the application of high-resolution imaging of trabecular bone but tend to involve high-power deposition. Increased availability of ultrahigh field scanners has opened new possibilities for imaging with increased signal-to-noise ratio (SNR) efficiency, but many pulse sequences that are standard at 1.5 and 3 T exceed specific absorption rate limits at 7 T. A modified, reduced specific absorption rate, three-dimensional, fast spin-echo pulse sequence optimized specifically for in vivo trabecular bone imaging at 7 T is introduced. The sequence involves a slab-selective excitation pulse, low-power nonselective refocusing pulses, and phase cycling to cancel undesired out-of-slab signal. In vivo images of the distal tibia were acquired using the technique at 1.5, 3, and 7 T field strengths, and SNR was found to increase at least linearly using receive coils of identical geometry. Signal dependence on the choice of refocusing flip angles in the echo train was analyzed experimentally and theoretically by combining the signal from hundreds of coherence pathways, and it is shown that a significant specific absorption rate reduction can be achieved with negligible SNR loss. PMID:20187181

  18. Preparation, ferromagnetic and photocatalytic performance of NiO and hollow Co{sub 3}O{sub 4} fibers through centrifugal-spinning technique

    SciTech Connect

    Feng, Cong; Lin, Xuejun; Wang, Xinqiang Liu, Hongjing; Liu, Benxue; Zhu, Luyi; Zhang, Guanghui; Xu, Dong

    2016-02-15

    Highlights: • NiO and hollow Co{sub 3}O{sub 4} fibers with the diameter of about 10 μm were prepared through centrifugal-spinning technique. • The evolution mechanism from precursor to crystalline fibers was explored. • Both NiO and hollow Co{sub 3}O{sub 4} fibers show ferromagnetism. • The NiO fibers exhibit good photocatalytic performance. - Abstract: Both NiO and hollow Co{sub 3}O{sub 4} fibers with the diameter of about 10 μm have been successfully prepared through spinning high viscous sols into precursor fibers and followed calcination process. The evolution process from precursor to crystalline fibers and the microstructures of the obtained fibers were characterized by TG-DSC, FT-IR, XRD, HRTEM, SEM and the like. The method is facile and cost-effective for mass production of fibers and the obtained fibers are pure phase with high crystallinity. Their magnetic properties were investigated, showing that both the fibers are ferromagnetic. Meanwhile, the NiO fibers exhibit good photocatalytic performance for the removal of Congo red from water under UV light irradiation.

  19. Spin Hall effect and spin swapping in diffusive superconductors

    NASA Astrophysics Data System (ADS)

    Espedal, Camilla; Lange, Peter; Sadjina, Severin; Mal'shukov, A. G.; Brataas, Arne

    2017-02-01

    We consider the spin-orbit-induced spin Hall effect and spin swapping in diffusive superconductors. By employing the nonequilibrium Keldysh Green's function technique in the quasiclassical approximation, we derive coupled transport equations for the spectral spin and particle distributions and for the energy density in the elastic scattering regime. We compute four contributions to the spin Hall conductivity, namely, skew scattering, side jump, anomalous velocity, and the Yafet contribution. The reduced density of states in the superconductor causes a renormalization of the spin Hall angle. We demonstrate that all four of these contributions to the spin Hall conductivity are renormalized in the same way in the superconducting state. In its simplest manifestation, spin swapping transforms a primary spin current into a secondary spin current with swapped current and polarization directions. We find that the spin-swapping coefficient is not explicitly but only implicitly affected by the superconducting gap through the renormalized diffusion coefficients. We discuss experimental consequences for measurements of the (inverse) spin Hall effect and spin swapping in four-terminal geometries. In our geometry, below the superconducting transition temperature, the spin-swapping signal is increased an order of magnitude while changes in the (inverse) spin Hall signal are moderate.

  20. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    SciTech Connect

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

    2015-05-07

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  1. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    NASA Astrophysics Data System (ADS)

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris

    2015-05-01

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  2. Effect of Fe incorporation on the optical behavior of ZnO thin films prepared by sol-gel derived spin coating techniques

    NASA Astrophysics Data System (ADS)

    Rakkesh, R. Ajay; Malathi, R.; Balakumar, S.

    2013-02-01

    In this work, Fe doped Zinc Oxide (ZnO) thin films were fabricated on the glass substrate by sol-gel derived spin coating technique. X-ray Diffraction studies revealed that the obtained pure and Fe doped ZnO thin films were in the wurtzite and spinel phase respectively. The three well defined Raman lines at 432, 543 and 1091 cm-1 also confirmed the lattice structure of the ZnO thin film has wurtzite symmetry. While doping Fe atoms in the ZnO, there was a significant change in the phase from wurtzite to spinel structure; owing to Fe (III) ions being incorporated into the lattice through substitution of Zn (II) ions. Room temperature PL spectra showed that the role of defect mediated red emissions at 612 nm was due to radial recombination of a photogenerated hole with an electron that belongs to the Fe atoms, which were discussed in detail.

  3. Spectroscopic properties of Eu3+, Dy3+ and Tb3+ ions in lead silicate glasses obtained by the conventional high-temperature melt-quenching technique

    NASA Astrophysics Data System (ADS)

    Żur, L.; Janek, J.; Sołtys, M.; Pisarska, J.; Pisarski, W. A.

    2013-11-01

    The luminescence properties of selected rare-earth ions in lead silicate glasses have been studied. Europium, dysprosium and terbium ions were chosen as active dopants. Based on excitation and emission measurements as well as luminescence decay analysis, some spectroscopic parameters for these lanthanide ions were determined. In particular, the intensity ratios R/O (Eu3+), Y/B (Dy3+) and G/B (Tb3+) were calculated. Luminescence lifetimes for the 5D0 state of Eu3+ ions, the 4F9/2 state of Dy3+ ions and the 5D4 state of Tb3+ ions were also determined.

  4. MR chemical exchange imaging with spin-lock technique (CESL): a theoretical analysis of the Z-spectrum using a two-pool R(1ρ) relaxation model beyond the fast-exchange limit.

    PubMed

    Yuan, Jing; Zhou, Jinyuan; Ahuja, Anil T; Wang, Yi-Xiang J

    2012-12-21

    The chemical exchange (CE) process has been exploited as a novel and powerful contrast mechanism for MRI, which is primarily performed in the form of chemical exchange saturation transfer (CEST) imaging. A spin-lock (SL) technique can also be used for CE studies, although traditionally performed and interpreted quite differently from CEST. Chemical exchange imaging with spin-lock technique (CESL), theoretically based on the Bloch-McConnell equations common to CEST, has the potential to be used as an alternative to CEST and to better characterize CE processes from slow and intermediate to fast proton exchange rates through the tuning of spin-lock pulse parameters. In this study, the Z-spectrum and asymmetric magnetization transfer ratio (MTR(asym)) obtained by CESL are theoretically analyzed and numerically simulated using a general two-pool R(1ρ) relaxation model beyond the fast-exchange limit. The influences of spin-lock parameters, static magnetic field strength B(0) and physiological properties on the Z-spectrum and MTR(asym) are quantitatively revealed. Optimization of spin-lock frequency and spin-lock duration for the maximum CESL contrast enhancement is also investigated. Numerical simulation results in this study are compatible with the findings in the existing literature on CE imaging studies.

  5. MR chemical exchange imaging with spin-lock technique (CESL): a theoretical analysis of the Z-spectrum using a two-pool R1ρ relaxation model beyond the fast-exchange limit

    NASA Astrophysics Data System (ADS)

    Yuan, Jing; Zhou, Jinyuan; Ahuja, Anil T.; Wang, Yi-Xiang J.

    2012-12-01

    The chemical exchange (CE) process has been exploited as a novel and powerful contrast mechanism for MRI, which is primarily performed in the form of chemical exchange saturation transfer (CEST) imaging. A spin-lock (SL) technique can also be used for CE studies, although traditionally performed and interpreted quite differently from CEST. Chemical exchange imaging with spin-lock technique (CESL), theoretically based on the Bloch-McConnell equations common to CEST, has the potential to be used as an alternative to CEST and to better characterize CE processes from slow and intermediate to fast proton exchange rates through the tuning of spin-lock pulse parameters. In this study, the Z-spectrum and asymmetric magnetization transfer ratio (MTRasym) obtained by CESL are theoretically analyzed and numerically simulated using a general two-pool R1ρ relaxation model beyond the fast-exchange limit. The influences of spin-lock parameters, static magnetic field strength B0 and physiological properties on the Z-spectrum and MTRasym are quantitatively revealed. Optimization of spin-lock frequency and spin-lock duration for the maximum CESL contrast enhancement is also investigated. Numerical simulation results in this study are compatible with the findings in the existing literature on CE imaging studies.

  6. Detection of free radical generation in the stunned' myocardium in the conscious dog using spin tripping techniques

    SciTech Connect

    Zughayb, M.; Sekili, S.; Li, X.Y., Triana, J.F.; McCay, P.B.; Bolli, R. Oklahoma Medical Research Foundation, Oklahoma City )

    1991-03-11

    Recent studies have shown that free radicals (FR) are produced in stunned' myocardium. However, since these studies were performed in open-chest animals, artifacts due to anesthesia, trauma, and other unphysiologic conditions cannot be excluded. FR production in conscious models of myocardial ischemia has never been shown. Thus, conscious dogs undergoing a 15-min coronary occlusion (O) followed by reperfusion (R) received i.v. the spin trap alpha-phenyl N-tert-butyl nitron (PBN) starting 5 min pre-O and ending 10 min after R. Local coronary venous effluent plasma was analyzed by electron paramagnetic resonance (EPR) spectroscopy. Myocardial production of PBN adducts was calculated as coronary flow x venous-arterial difference in EPR signal intensity. A burst of PBN adduct production was observed in the first 5 min of R. Adduct production then abated but remained detectable for several hours after R. Coupling constants are consistent with a complex mixture of FR. In 5 control studies, infusion of PBN without ischemia was not associated with appreciable adduct production. These results demonstrate that reversible regional myocardial ischemia in the conscious animal is associated with free radical generation and further support the hypothesis that oxy-radicals contribute to stunning.

  7. Technique paper for wet-spinning poly(L-lactic acid) and poly(DL-lactide-co-glycolide) monofilament fibers.

    PubMed

    Nelson, Kevin D; Romero, Andres; Waggoner, Paula; Crow, Brent; Borneman, Angela; Smith, George M

    2003-12-01

    A simple and repeatable method is described for wet-spinning poly(L-lactic acid) (PLLA) and poly(DL-lactic-co-glycolic acid) (PLGA) monofilament fibers. These fibers are strong, elastic, and suitable for many applications, including use as tissue-engineering scaffolds. The PLLA wet-extruded fibers do not show additional strain-induced crystallization as a result of drawing the fibers during fabrication; however, there is an apparent increase in crystallinity late in the degradation process in saline at 37 degrees C. We have measured the molecular weight degradation in saline at 37 degrees C for fibers of both PLLA and PLGA. Changing solvent systems, polymer blends, and winding rates alters mechanical and morphological properties of these fibers for specific applications. The authors discuss a possible theoretical explanation for these observed changes due to changes in polymer concentration, solvent system, and coagulation bath properties. This wet-extrusion process is simple and inexpensive enough to be carried out in almost any laboratory interested in tissue engineering.

  8. Enhanced Magnetic Properties of Nd15Fe77B8 Alloy Powders Produced by Melt-Spinning Technique

    NASA Astrophysics Data System (ADS)

    Öztürk, Sultan; İcin, Kürşat; Öztürk, Bülent; Topal, Uğur; Odabaşı, Hülya Kaftelen; Göbülük, Metin; Cora, Ömer Necati

    2017-10-01

    Rapidly solidified Nd15Fe77B8 alloy powders were produced by means of melt-spinning method in high-vacuum atmosphere to achieve improved magnetic and thermal properties. To this goal, a vacuum milling apparatus was designed and constructed to ball-mill the melt-spun powders in a surfactant active atmosphere. Various milling times were experimented to reveal the effect of the milling time on the mean particle size and other size-dependent properties such as magnetism and Curie temperature. Grain structure, cooling rate, and phase structure of the produced powders were also investigated. The Curie points shifted to higher temperatures from the ingot condition to surfactant active ball-milling and the values for Nd15Fe77B8 ingot alloy, melt-spun powders, and surfactant active ball-milled powders were 552 K, 595 K, and 604 K (279 °C, 322 °C, and 331 °C), respectively. It was noted that the surfactant active ball-milling process improved the magnetic and thermal properties of melt-spun Nd15Fe77B8 alloy powders. Compared to relevant literature, the coercivity of powders increased significantly with increasing milling time and decreasing in powder size. The coercivity value as high as 3427 kA m-1 was obtained.

  9. Observing Black Hole Spin

    NASA Astrophysics Data System (ADS)

    Reynolds, Christopher S.

    2015-08-01

    Black hole spin is important in both the fundamental physics and astrophysics realms. In fundamental terms, many extensions and alternatives to General Relativity (GR) reveal themselves through effects related to (or at least of the same order as) spin. Astrophysically, spin is a fossil record of how black holes have grown and may, in addition, be an important source of energy (e.g., powering relativistic jets from black hole systems). I shall review recent progress on observational studies of black hole spin, especially those made in the X-ray waveband. We now have multiple techniques that can be applied in our search for black hole spin; I shall discuss the concordance (or, sometimes, lack thereof) between these techniques. Finally, I shall discuss what we can expect in the next few years with the launch of new X-ray instrumentation as well as the deployment of the Event Horizon Telescope.

  10. Quantitative analysis of the breath-holding half-Fourier acquisition single-shot turbo spin-echo technique in abdominal MRI

    NASA Astrophysics Data System (ADS)

    Dong, Kyung-Rae; Goo, Eun-Hoe; Lee, Jae-Seung; Chung, Woon-Kwan

    2013-01-01

    A consecutive series of 50 patients (28 males and 22 females) who underwent hepatic magnetic resonance imaging (MRI) from August to December 2011 were enrolled in this study. The appropriate parameters for abdominal MRI scans were determined by comparing the images (TE = 90 and 128 msec) produced using the half-Fourier acquisition single-shot turbo spin-echo (HASTE) technique at different signal acquisition times. The patients consisted of 15 normal patients, 25 patients with a hepatoma and 10 patients with a hemangioma. The TE in a single patient was set to either 90 msec or 128 msec. This was followed by measurements using the four normal rendering methods of the biliary tract system and the background signal intensity using the maximal signal intensity techniques in the liver, spleen, pancreas, gallbladder, fat, muscles and hemangioma. The signal-to-noise and the contrast-to-noise ratios were obtained. The image quality was assessed subjectively, and the results were compared. The signal-to-noise and the contrast-to-noise ratios were significantly higher at TE = 128 msec than at TE = 90 when diseases of the liver, spleen, pancreas, gallbladder, and fat and muscles, hepatocellular carcinomas and hemangiomas, and rendering the hepatobiliary tract system based on the maximum signal intensity technique were involved (p < 0.05). In addition, the presence of artifacts, the image clarity and the overall image quality were excellent at TE = 128 msec (p < 0.05). In abdominal MRI, the breath-hold half-Fourier acquisition single-shot turbo spin-echo (HASTE) was found to be effective in illustrating the abdominal organs for TE = 128 msec. Overall, the image quality at TE = 128 msec was better than that at TE = 90 msec due to the improved signal-to-noise (SNR) and contrast-to-noise (CNR) ratios. Overall, the HASTE technique for abdominal MRI based on a high-magnetic field (3.0 T) at a TE of 128 msec can provide useful data.

  11. Spectroscopic characterization of polymers: report

    SciTech Connect

    Koenig, J.L.

    1987-10-01

    Polymer characterization has presented major difficulties to the analytical chemist, who has had to develop techniques to cope with the challenge. Even the elementary problem of measuring molecular weight is not easy. Yet such measurements are essential, because the physical, mechanical, and flow properties depend on the length of the polymer chain. Because of the limited solubility and high viscosity of polymers, many classical techniques have been of little use or have had to be extensively modified to measure the molecular weight of polymers. Size-exclusion chromatographic techniques such as gel permeation have been developed to measure these molecular weight distributions. Special chromatographic instruments with a range of spectroscopic detectors (including infrared and laser-light scattering) have emerged commercially to aid the analytical chemist in the fundamental endeavor to measure the length of the polymer chain and its distribution. The author describes the advantages and disadvantages and disadvantages of various spectroscopic techniques.

  12. Optical Pumping of Rubidium Spin in a Solid Argon Matrix

    NASA Astrophysics Data System (ADS)

    Regmi, Sameer K.

    Using the matrix isolation technique we have trapped rubidium atoms inside a cryogenic solid argon crystal of thickness 200 mum. This weakly-interacting solid offers the experimental simplicity and high densities of solid-state systems, while allowing the implanted atoms to retain many of the properties of their gas-phase counterparts. As such, they are a promising environment for quantum information experiments, as well as sensors such as magnetometers. We spectroscopically observed narrow lines at 799 nm, 785 nm, and 747 nm, and investigated optical pumping of the implanted rubidium atoms. We observed that the absorption spectrum of the rubidium could be modified by incident laser light. This modification could be reversed by applying an additional light source. In addition, we were able to create spin polarization and measure a longitudinal spin relaxation time T1 of about 0.1 s.

  13. The application of thermodynamic and spectroscopic techniques to adhesion in the polyimide/Ti 6-4 and polyphenylquinoxaline/Ti 6-4 systems

    NASA Technical Reports Server (NTRS)

    Dias, S.; Wightman, J. P.

    1984-01-01

    The results of calorimetric measurements of Ti adherend surfaces are presented. The measurements were carried out after several chemical pretreatments and after fracture of several lap shear samples aged at high temperature. The exact composition of the Ti samples was Ti(6 percent Al-4 percent V). The adhesives used were polyimides and polyphenylquinoxalines (PPQ). Each chemical pretreatment was accompanied by a unique spectroscopic feature which was characterized by XPS, SEM, and specular reflectance infrared spectroscopy. The energetics of the interaction between primer solutions and the Ti adherend were evaluated by microcalorimetry. Changes in the structure of the surface oxide layer upon heating of the adherend were deduced from immersion temperatures of the PI and PPQ solutions. The XPS and SEM data are given is a table.

  14. High-spin states in 208Rn

    NASA Astrophysics Data System (ADS)

    Triggs, W. J.; Poletti, A. R.; Dracoulis, G. D.; Fahlander, C.; Byrne, A. P.

    1983-03-01

    The yrast decay scheme of 208Rn has been investigated up to spin ≈ 20 h̵ and an excitation energy of ≈ 6 MeV. Several different γ-ray spectroscopic techniques were used to determine the properties of excited states and transitions in the nucleus. Significant changes to the previously established level scheme are proposed, based on the existence of an unobserved 3.1 keV transition. Simple empirical shell-model calculations of level energies aided in the assignment of shell-model configurations to excited states and the decay scheme is discussed in terms of these configurations. The energy level systematics for the even radon isotopes, from A = 206 to 212 are discussed, as are core polarization effects in the even radon isotopes ( A = 204 to 210) and polonium isotopes ( A = 202-208).

  15. Spin polarization measurements of ferromagnetic atomic chains on a superconductor: Part I

    NASA Astrophysics Data System (ADS)

    Xie, Yonglong; Jeon, Sangjun; Drozdov, Ilya; Li, Jian; Bernevig, Andrei; Yazdani, Ali

    Introduction of magnetic defects in superconductors gives rise to spin polarized in-gap Shiba states. Recently chains of magnetic atoms, which give rise to a band of Shiba states, have been proposed as a platform for topological superconductivity. Spectroscopic evidence for in-gap Shiba states and Majorana end mode has been reported in previous studies of self-assembled chains of ferromagnetic Fe atoms on the surface of Pb. In this talk, we introduce the technique of spin-polarized scanning tunneling microscopy and spectroscopy (SP-STM) and discuss how we prepare tips that can show spin contrast at zero magnetic field, without disrupting superconductivity on the Pb surface. We use this technique, combined with the use of a vector magnet to orient the tip magnetization to probe the spin polarization of the Shiba states induced by the Fe atomic chains onto the Pb surface. A key to interpreting such experiments with spin-polarized STM tip is to understand the role of spin-polarization in the setpoint effect, which will be discussed in the next talk. Work supported by ONR and Moore Foundation.

  16. Experimental comparison of four FAIR arterial spin labeling techniques for quantification of mouse cerebral blood flow at 4.7 T.

    PubMed

    Kober, Frank; Duhamel, Guillaume; Cozzone, Patrick J

    2008-10-01

    Pulsed arterial spin labeling (ASL) is an attractive and robust method for quantification of rodent cerebral blood flow (CBF) in particular, although there is a need for sensitivity optimization. Look-Locker flow-sensitive alternating inversion recovery (FAIR) echo planar imaging (EPI) (LLFAIREPI) was expected to be a likely candidate for assessing sensitivity, although it has not yet been applied to rodents. In this study, the performance of two FAIR techniques and two Look-Locker FAIR techniques were compared in mouse brain at 4.7 T. FAIR-EPI (single inversion time, FAIREPI-1TI), FAIR-EPI (eight inversion times, FAIREPI-8TI), LLFAIREPI and Look-Locker FAIR gradient echo (LLFAIRGE) sequences were implemented with equal spatial resolution and equal FAIR preparation modules. Measurements were carried out sequentially on the brain in 10 healthy mice, and quantitative CBF maps were obtained after different acquisition times up to 23 min. All methods gave similar group variability in CBF. Especially at shorter acquisition times, LLFAIREPI gave lower relative variations in CBF within selected brain regions than the other techniques at the same acquisition time. The Look-Locker techniques, however, overestimated CBF compared with classical FAIR-EPI, which was attributed to bulk flow in arterioles and T(2) effects. The image quality with LLFAIREPI was less reproducible within the group. Both FAIREPI-1TI and LLFAIREPI appear to be good candidates for serial rapid measurement of CBF, but LLFAIREPI has the additional advantage that apparent T(1) can be measured simultaneously with CBF. Copyright (c) 2008 John Wiley & Sons, Ltd.

  17. Direct evidence for inhibition of free radical formation from Cu(I) and hydrogen peroxide by glutathione and other potential ligands using the EPR spin-trapping technique.

    PubMed

    Hanna, P M; Mason, R P

    1992-05-15

    Copper-induced oxidative damage is generally attributed to the formation of the highly reactive hydroxyl radical by a mechanism analogous to the Haber-Weiss cycle for Fe(II) and H2O2. In the present work, the reaction between the Cu(I) ion and H2O2 is studied using the EPR spin-trapping technique. The hydroxyl radical adduct was observed when Cu(I), dissolved in acetonitrile under N2, was added to pH 7.4 phosphate buffer containing 100 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Formation of the hydroxyl radical was dependent on the presence of O2 and subsequent formation of H2O2. The kscav/kDMPO ratios obtained were below those expected for a mechanism involving free hydroxyl radical and reflect the interference of nucleophilic addition of H2O to DMPO to form the DMPO/.OH adduct in the presence of nonchelated copper ion. Addition of ethanol or dimethyl sulfoxide to the reaction suggests that a high-valent metal intermediate, possibly Cu(III), was also formed. Spin trapping of hydroxyl radical was almost completely inhibited upon addition of Cu(I) to a solution of either nitrilotriacetate or histidine, even though the copper was fully oxidized to Cu(II) and H2O2 was formed. Bathocuproinedisulfonate, thiourea, and reduced glutathione all stabilized the Cu(I) ion toward oxidation by O2. Upon addition of H2O2, the Cu(I) in all three complexes was oxidized to varying degrees; however, only the thiourea complex was fully oxidized within 2 min of reaction and produced detectable hydroxyl radicals. No radicals were detected from the bathocuproinedisulfonate or glutathione complexes. Overall, these results suggest that the deleterious effects of copper ions in vivo are diminished by biochemical chelators, especially glutathione, which probably has a major role in moderating the toxicological effects of copper.

  18. Effect of iron doping on structural and optical properties of TiO2 thin film by sol-gel routed spin coating technique

    NASA Astrophysics Data System (ADS)

    Lourduraj, Stephen; Williams, Rayar Victor

    Thin films of iron (Fe)-doped titanium dioxide (Fe:TiO2) were prepared by sol-gel spin coating technique and further calcined at 450∘C. The structural and optical properties of Fe-doped TiO2 thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-vis) and atomic force microscopic (AFM) techniques. The XRD results confirm the nanostructured TiO2 thin films having crystalline nature with anatase phase. The characterization results show that the calcined thin films having high crystallinity and the effect of iron substitution lead to decreased crystallinity. The SEM investigations of Fe-doped TiO2 films also gave evidence that the films were continuous spherical shaped particles with a nanometric range of grain size and film was porous in nature. AFM analysis establishes that the uniformity of the TiO2 thin film with average roughness values. The optical measurements show that the films having high transparency in the visible region and the optical band gap energy of Fe-doped TiO2 film with iron (Fe) decrease with increase in iron content. These important requirements for the Fe:TiO2 films are to be used as window layers in solar cells.

  19. Influence of Ga doping ratio on the saturable absorption mechanism in Ga doped ZnO thin solid films processed by sol-gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.; Byrappa, K.

    2017-03-01

    In the present study, the nonlinear optical properties of sol-gel spin coated gallium doped zinc oxide (GZO) thin solid films are explored with nanosecond laser pulses using the z-scan technique. The higher doping ratios of Ga result in a large redshift of the energy gap (0.38 eV) due to the existence of enhanced grain boundary defects in GZO films. A positive nonlinear absorption coefficient is observed in undoped 1 at.wt.% GZO and 2 at.wt.% GZO films, and a negative nonlinear absorption coefficient in 3 at.wt.% GZO film. Fewer defects in undoped 1% GZO and 2% GZO films resulted in reverse saturable absorption (RSA), whereas a saturable absorption (SA) mechanism is observed in 3% GZO films and is attributed to the enhanced defect concentration in the band structure of GZO. However, all the films showed a self-defocusing mechanism, derived by a closed aperture z-scan technique. The present work sheds light on the defect mechanism involved in the observed nonlinear properties of GZO films.

  20. Arterial Spin Labeling - Fast Imaging with Steady-State Free Precession (ASL-FISP): A Rapid and Quantitative Perfusion Technique for High Field MRI

    PubMed Central

    Gao, Ying; Goodnough, Candida L.; Erokwu, Bernadette O.; Farr, George W.; Darrah, Rebecca; Lu, Lan; Dell, Katherine M.; Yu, Xin; Flask, Chris A.

    2014-01-01

    Arterial Spin Labeling (ASL) is a valuable non-contrast perfusion MRI technique with numerous clinical applications. Many previous ASL MRI studies have utilized either Echo-Planar Imaging (EPI) or True Fast Imaging with Steady-State Free Precession (True FISP) readouts that are prone to off-resonance artifacts on high field MRI scanners. We have developed a rapid ASL-FISP MRI acquisition for high field preclinical MRI scanners providing perfusion-weighted images with little or no artifacts in less than 2 seconds. In this initial implementation, a FAIR (Flow-Sensitive Alternating Inversion Recovery) ASL preparation was combined with a rapid, centrically-encoded FISP readout. Validation studies on healthy C57/BL6 mice provided consistent estimation of in vivo mouse brain perfusion at 7 T and 9.4 T (249±38 ml/min/100g and 241±17 ml/min/100g, respectively). The utility of this method was further demonstrated in detecting significant perfusion deficits in a C57/BL6 mouse model of ischemic stroke. Reasonable kidney perfusion estimates were also obtained for a healthy C57/BL6 mouse exhibiting differential perfusion in the renal cortex and medulla. Overall, the ASL-FISP technique provides a rapid and quantitative in vivo assessment of tissue perfusion for high field MRI scanners with minimal image artifacts. PMID:24891124

  1. Arterial spin labeling-fast imaging with steady-state free precession (ASL-FISP): a rapid and quantitative perfusion technique for high-field MRI.

    PubMed

    Gao, Ying; Goodnough, Candida L; Erokwu, Bernadette O; Farr, George W; Darrah, Rebecca; Lu, Lan; Dell, Katherine M; Yu, Xin; Flask, Chris A

    2014-08-01

    Arterial spin labeling (ASL) is a valuable non-contrast perfusion MRI technique with numerous clinical applications. Many previous ASL MRI studies have utilized either echo-planar imaging (EPI) or true fast imaging with steady-state free precession (true FISP) readouts, which are prone to off-resonance artifacts on high-field MRI scanners. We have developed a rapid ASL-FISP MRI acquisition for high-field preclinical MRI scanners providing perfusion-weighted images with little or no artifacts in less than 2 s. In this initial implementation, a flow-sensitive alternating inversion recovery (FAIR) ASL preparation was combined with a rapid, centrically encoded FISP readout. Validation studies on healthy C57/BL6 mice provided consistent estimation of in vivo mouse brain perfusion at 7 and 9.4 T (249 ± 38 and 241 ± 17 mL/min/100 g, respectively). The utility of this method was further demonstrated in the detection of significant perfusion deficits in a C57/BL6 mouse model of ischemic stroke. Reasonable kidney perfusion estimates were also obtained for a healthy C57/BL6 mouse exhibiting differential perfusion in the renal cortex and medulla. Overall, the ASL-FISP technique provides a rapid and quantitative in vivo assessment of tissue perfusion for high-field MRI scanners with minimal image artifacts. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Computer-aided classification of patients with dementia of Alzheimer's type based on cerebral blood flow determined with arterial spin labeling technique

    NASA Astrophysics Data System (ADS)

    Yamashita, Yasuo; Arimura, Hidetaka; Yoshiura, Takashi; Tokunaga, Chiaki; Magome, Taiki; Monji, Akira; Noguchi, Tomoyuki; Toyofuku, Fukai; Oki, Masafumi; Nakamura, Yasuhiko; Honda, Hiroshi

    2010-03-01

    Arterial spin labeling (ASL) is one of promising non-invasive magnetic resonance (MR) imaging techniques for diagnosis of Alzheimer's disease (AD) by measuring cerebral blood flow (CBF). The aim of this study was to develop a computer-aided classification system for AD patients based on CBFs measured by the ASL technique. The average CBFs in cortical regions were determined as functional image features based on the CBF map image, which was non-linearly transformed to a Talairach brain atlas by using a free-form deformation. An artificial neural network (ANN) was trained with the CBF functional features in 10 cortical regions, and was employed for distinguishing patients with AD from control subjects. For evaluation of the method, we applied the proposed method to 20 cases including ten AD patients and ten control subjects, who were scanned a 3.0-Tesla MR unit. As a result, the area under the receiver operating characteristic curve obtained by the proposed method was 0.893 based on a leave-one-out-by-case test in identification of AD cases among 20 cases. The proposed method would be feasible for classification of patients with AD.

  3. Thermal- and light-induced spin crossover in novel 2D Fe(II) metalorganic frameworks {Fe(4-PhPy)(2)[M(II)(CN)(x)](y)}.sH(2)O: spectroscopic, structural, and magnetic studies.

    PubMed

    Seredyuk, M; Gaspar, A B; Ksenofontov, V; Verdaguer, M; Villain, F; Gütlich, P

    2009-07-06

    Five novel two-dimensional coordination polymers {Fe(4PhPy)(2)[M(II)(CN)(4)]}.sH(2)O (4PhyPy = 4-phenylpyridine; 1: M(II) = Pd, s = 0; 2: M(II) = Ni, s = 0; 3: M(II) = Pt, s = 1) and {Fe(4PhPy)(2)[M(I)(CN)(2)](2)}.sH(2)O (4: M(I) = Ag, s = 1; 5: M(I) = Au, s = 0.5) exhibiting spin-crossover properties have been synthesized. They were characterized at various temperatures using X-ray absorption spectroscopy (XAS), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and magnetic susceptibility measurements. The occurrence of a cooperative thermal spin transition detected by the magnetic method is located at critical temperatures T(c)( downward arrow)/T(c)( upward arrow) = 163 K/203 K (1), 135 K/158 K (2), and 172 K/221 K (3), and a less cooperative one is located at T(c) = 188 K (4) and 225 K (5). Compounds 1-5 show an abrupt color change from yellow (high-spin (HS) state) to red (low-spin (LS) state) upon spin-state conversion. The dehydration of the compounds changes the type of the spin transition, making it more abrupt and shifting the critical temperature to higher temperatures. For 1 and 2, XAS provides local structural information on the contraction of the FeN(6) coordination sphere upon the HS-to-LS transition, in line with the magnetic results. Variable-temperature characterization of 1 by X-ray diffraction evidences the very abrupt phase transition with a large hysteresis. A light-induced spin conversion (LIESST effect) is detected by magnetic measurements in 1-5 below 70 K.

  4. Spectroscopic studies of the cytochrome P450 reaction mechanisms.

    PubMed

    Mak, Piotr J; Denisov, Ilia G

    2017-06-28

    The cytochrome P450 monooxygenases (P450s) are thiolate heme proteins that can, often under physiological conditions, catalyze many distinct oxidative transformations on a wide variety of molecules, including relatively simple alkanes or fatty acids, as well as more complex compounds such as steroids and exogenous pollutants. They perform such impressive chemistry utilizing a sophisticated catalytic cycle that involves a series of consecutive chemical transformations of heme prosthetic group. Each of these steps provides a unique spectral signature that reflects changes in oxidation or spin states, deformation of the porphyrin ring or alteration of dioxygen moieties. For a long time, the focus of cytochrome P450 research was to understand the underlying reaction mechanism of each enzymatic step, with the biggest challenge being identification and characterization of the powerful oxidizing intermediates. Spectroscopic methods, such as electronic absorption (UV-Vis), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), electron nuclear double resonance (ENDOR), Mössbauer, X-ray absorption (XAS), and resonance Raman (rR), have been useful tools in providing multifaceted and detailed mechanistic insights into the biophysics and biochemistry of these fascinating enzymes. The combination of spectroscopic techniques with novel approaches, such as cryoreduction and Nanodisc technology, allowed for generation, trapping and characterizing long sought transient intermediates, a task that has been difficult to achieve using other methods. Results obtained from the UV-Vis, rR and EPR spectroscopies are the main focus of this review, while the remaining spectroscopic techniques are briefly summarized. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials

    NASA Astrophysics Data System (ADS)

    Callewaert, Vincent; Shastry, K.; Saniz, Rolando; Makkonen, Ilja; Barbiellini, Bernardo; Assaf, Badih A.; Heiman, Donald; Moodera, Jagadeesh S.; Partoens, Bart; Bansil, Arun; Weiss, A. H.

    2016-09-01

    Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control, and manipulate the topological surface states, spectroscopic tools which can effectively probe their properties are of key importance. Here, we demonstrate that positrons provide a sensitive probe for topological states and that the associated annihilation spectrum provides a technique for characterizing these states. Firm experimental evidence for the existence of a positron surface state near Bi2Te2Se with a binding energy of Eb=2.7 ±0.2 eV is presented and is confirmed by first-principles calculations. Additionally, the simulations predict a significant signal originating from annihilation with the topological surface states and show the feasibility to detect their spin texture through the use of spin-polarized positron beams.

  6. Isolation and Control of Spins in Silicon Carbide with Millisecond-Coherence Times

    NASA Astrophysics Data System (ADS)

    Christle, David J.; Falk, Abram L.; Andrich, Paolo; Klimov, Paul V.; Awschalom, David D.; Hassan, Jawad Ul; Son, Nguyen T.; Janzén, Erik; Ohshima, Takeshi

    2015-03-01

    The elimination of defects from silicon carbide (SiC) has facilitated its move to the forefront of the optoelectronics and power-electronics industries. Nonetheless, because the electronic states of SiC defects can have sharp optical and spin transitions, they are increasingly recognized as a valuable resource for quantum-information and nanoscale-sensing applications. We demonstrate that individual electronic spin states of the divacancy defect in highly purified monocrystalline 4H-SiC can be isolated and coherently controlled. This defect has analogous behavior to the prominent nitrogen-vacancy center in diamond, yet exists in a material amenable to modern growth and microfabrication techniques. We spectroscopically identify the different forms of divacancies, and show that divacancy spins exhibit an exceptionally long ensemble Hahn-echo coherence time that exceeds one millisecond. Funding by NSF, AFOSR MURI, and the Knut & Alice Wallenberg Foundation is gratefully acknowledged.

  7. Synthesis, structural, and spectroscopic (FT-IR, NMR, and UV) Characterization of 1-(Cyclohexylmethyl)-2-(pyridin-2-yl)-1 H-benzo[ d]imidazole by experimental techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Özdemir, Namık; Dayan, Osman; Demirmen, Selin

    2016-05-01

    The title compound ( II), 1-(cyclohexylmethyl)-2-(pyridin-2-yl)-1 H-benzo[ d]imidazole (C19H21N3), was synthesized via N-alkylation of 2-(pyridin-2-yl)-1 H-benzo[ d]imidazole ( I). Both compounds I and II were characterized by IR, NMR and UV-vis spectroscopy. Solid-state structure of compound II was determined by single-crystal X-ray diffraction technique. Furthermore, quantum chemical calculations employing density functional theory (DFT/B3LYP) method with the 6-311++ G( d, p) basis set were performed for the theoretical characterization of the molecular and spectroscopic features of the compounds. Using the TD-DFT method, electronic absorption spectra of the compounds have been predicted at same level. When the obtained results were compared with the experimental findings, it is seen that theoretical results support the experimental data and a good agreement exists between them.

  8. Mitigating the hydraulic compression of nanofiltration hollow fiber membranes through a single-step direct spinning technique.

    PubMed

    Ong, Yee Kang; Chung, Tai-Shung

    2014-12-02

    Most nanofiltration (NF) membranes have been made through complicated multistep or thin-film composite processes. They also suffer the compaction issue that reduces permeate flux in pressure-driven filtration processes. A single-step coextrusion hollow fiber fabrication technique via immiscibility induced phase separation (I(2)PS) process is presented in this study to fabricate NF hollow fiber membranes. A protective layer is concurrently formed on top of the selective layer during the phase inversion process. The fabricated hollow fiber membrane has a narrow pore size distribution with a molecular weight cutoff (MWCO) of 470 Da. The outer layer of the I(2)PS hollow fiber is found to serve as a buffering layer that mitigates hydraulic compression on the compaction of dense-selective layer and sublayer and helps to retain membrane performance during nanofiltration operations. The newly fabricated NF hollow fiber membrane exhibits an average pure water permeability of 3.2 L m(-2) h(-1) bar(-1) and shows good rejections toward the testing dyes. This study may offer a simple, direct, and cost-effective approach to fabricate NF hollow fiber membranes.

  9. Structure analysis and spectroscopic characterization of 2-Fluoro-3-Methylpyridine-5-Boronic Acid with experimental (FT-IR, Raman, NMR and XRD) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Alver, Özgür; Dikmen, Gökhan

    2016-03-01

    Possible stable conformers, geometrical molecular structures, vibrational properties as well as band assignments, nuclear magnetic shielding tensors of 2-Fluoro-3-Methylpyridine-5-Boronic Acid (2F3MP5BA) were studied experimentally and theoretically using FT-IR, Raman, (CP/MAS) NMR and XRD spectroscopic methods. FT-IR and Raman spectra were evaluated in the region of 3500-400 cm-1, and 3200-400 cm-1, respectively. The optimized geometric structures, vibrational wavenumbers and nuclear magnetic shielding tensors were examined using Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. 1H, 13C NMR chemical shifts were calculated using the gauge invariant atomic orbital (GIAO) method. 1H, 13C, APT and HETCOR NMR experiments of title molecule were carried out in DMSO solution. 13C CP/MAS NMR measurement was done with 4 mm zirconium rotor and glycine was used as an external standard. Single crystal of 2F3MP5BA was also prepared for XRD measurements. Assignments of vibrational wavenumbers were also strengthened by calculating the total energy distribution (TED) values using scaled quantum mechanical (SQM) method.

  10. Detection of β-amyloid peptide (1-16) and amyloid precursor protein (APP770) using spectroscopic ellipsometry and QCM techniques: a step forward towards Alzheimers disease diagnostics.

    PubMed

    Mustafa, M K; Nabok, A; Parkinson, D; Tothill, I E; Salam, F; Tsargorodskaya, A

    2010-12-15

    A highly sensitive method of spectroscopic ellipsometry in total internal reflection mode (TIRE) was exploited for detecting β-amyloid peptide (Aβ(1-16)) in the direct immune reaction with monoclonal DE2 antibodies (raised against Aβ(1-16)) electrostatically immobilised on the surface of gold. A rapid detection of Aβ(1-16) in a wide range of concentrations from 5 μg/ml down to 0.05 ng/ml was achieved using a cost-effective and label-free direct immunoassay format. TIRE dynamic spectral measurements proved that the immune reaction between DE2 monoclonal antibodies and Aβ(1-16) is highly specific with the affinity constant K(D)=1.46×10(-8) mol/l. The same DE2 antibodies were utilised for detection of amyloid precursor protein APP(770), a larger protein containing Aβ(1-16) domain, using the quartz crystal microbalance (QCM) measurements in liquid. A combination of QCM and TIRE kinetics results allowed the evaluation of the originally unknown concentration of APP(770) in complete medium solution containing other proteins, salts, and amino acids.

  11. Study on the interaction between pelargonidin-3-O-glucoside and bovine serum albumin using spectroscopic, transmission electron microscopy and molecular modeling techniques.

    PubMed

    Li, Shu; Tang, Lin; Bi, Hongna

    2016-03-01

    The aim of this study is to evaluate the binding behavior between pelargonidin-3-O-glucoside (P3G) and bovine serum albumin (BSA) using multi-spectroscopic, transmission electron microscopy (TEM) and molecular docking methods under physiological conditions. Fluorescence spectroscopy and time-resolved fluorescence showed that the fluorescence of BSA could be quenched remarkably by P3G via a static quenching mechanism, and there is a single class of binding site on BSA. In addition, the thermodynamic functions ΔH and ΔS were -21.69 kJ/mol and 24.46 J/mol/K, indicating that an electrostatic interaction was a main acting force. The distance between BSA and P3G was 2.74 nm according to Förster's theory, illustrating that energy transfer occurred. In addition, the secondary structure of BSA changed with a decrease in the α-helix content from 66.2% to 64.0% as seen using synchronous fluorescence, UV/vis, circular dichroism and Fourier transform infrared spectroscopies, whereas TEM images showed that P3G led to BSA aggregation and fibrillation. Furthermore, site marker competitive experiments and molecular docking indicated that P3G could bind with subdomain IIA of BSA. The calculated results of the equilibrium fraction showed that the concentration of free P3G in plasma was high enough to be stored and transported from the circulatory system to its target sites to provide therapeutic effects.

  12. Single spin magnetic resonance

    NASA Astrophysics Data System (ADS)

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  13. Single spin magnetic resonance.

    PubMed

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Towards a Compositional SPIN

    NASA Technical Reports Server (NTRS)

    Pasareanu, Corina S.; Giannakopoulou, Dimitra

    2006-01-01

    This paper discusses our initial experience with introducing automated assume-guarantee verification based on learning in the SPIN tool. We believe that compositional verification techniques such as assume-guarantee reasoning could complement the state-reduction techniques that SPIN already supports, thus increasing the size of systems that SPIN can handle. We present a "light-weight" approach to evaluating the benefits of learning-based assume-guarantee reasoning in the context of SPIN: we turn our previous implementation of learning for the LTSA tool into a main program that externally invokes SPIN to provide the model checking-related answers. Despite its performance overheads (which mandate a future implementation within SPIN itself), this approach provides accurate information about the savings in memory. We have experimented with several versions of learning-based assume guarantee reasoning, including a novel heuristic introduced here for generating component assumptions when their environment is unavailable. We illustrate the benefits of learning-based assume-guarantee reasoning in SPIN through the example of a resource arbiter for a spacecraft. Keywords: assume-guarantee reasoning, model checking, learning.

  15. Spectroscopic Properties and Potential Energy Curves of SnF +

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.; Xu, H.

    1995-06-01

    Spectroscopic properties and potential energy curves of several electronic states of SnF+ are computed using the complete active space self-consistent field (CASSCF) followed by first- and second-order configuration interaction (FOCI, SOCI) methods that include up to 1.6 million configurations. Spin-orbit effects were incorporated using the relativistic configuration interaction (RCI) method. Spectroscopic properties of several excited electronic states of SnF+ are reported, none of which is observed at present.

  16. Spin diffusion length of Permalloy using spin absorption in lateral spin valves

    NASA Astrophysics Data System (ADS)

    Sagasta, Edurne; Omori, Yasutomo; Isasa, Miren; Otani, YoshiChika; Hueso, Luis E.; Casanova, Fèlix

    2017-08-01

    We employ the spin absorption technique in lateral spin valves to extract the spin diffusion length of Permalloy (Py) as a function of temperature and resistivity. A linear dependence of the spin diffusion length with the conductivity of Py is observed, evidencing that the Elliott-Yafet mechanism is the dominant spin relaxation mechanism in Permalloy. Completing the dataset with additional data found in the literature, we obtain λPy = (0.91 ± 0.04) (fΩm2)/ρPy.

  17. Spectroscopic and structural investigations of the ferrous and ferric high-spin state of a ``picket—fence'' porphyrinato acetato iron complex. A refined model for the P460 center of hydroxylamine oxidoreductase

    NASA Astrophysics Data System (ADS)

    Bill, E.; Bominaar, E. L.; Ding, X.-O.; Fischer, J.; Gismelseed, A.; Nasri, H.; Trautwein, A. X.; Weiss, R.; Winkler, H.

    1992-04-01

    Mössbauer investigations were performed in the ferrous and ferric form of the ‘picket-fence’ porphyrinato acetato iron complex |Fe(CH3CO2) (TPpivP)|1-,0 at temperatures varying from 1.5 200K and in fields of 0 6.2T. The ferrous complex has an unusually large quadrupole splitting, ΔEQ=+4.25mms-1. The quadrupole splitting in the ferric species, ΔEQ=+1.1mms-1, is as normally found in ferric high-spin iron porphyrins. Spin-Hamiltonian analysis of the magnetic spectra yields zero-field parameters D=-0.9mms-1, E/D=0.33 and magnetic hyperfine parameters Ax,y=-17T, Az=-13.3T in the ferrous high-spin (S=2) complex, and D=7.5cm-1, E/D≈0 and Ax,y,z=20T in the ferric high-spin (S=5/2) species.

  18. Spectroscopic techniques and cyclic voltammetry with synthesis: Manganese(II) coordination stability and its ligand field parameters effect on macrocyclic ligands

    NASA Astrophysics Data System (ADS)

    Kumar, Rajiv; Chandra, Sulekh

    2007-05-01

    Manganese(II) macrocyclic complexes are prepared with different macrocyclic ligands, containing cyclic skeleton bearing organic components which have different chromospheres like N, O and S donor atoms and stereochemistry. Thus, six macrocyclic ligands, were prepared and their capacity to retain the manganese(II) ion in solid as well as in aqueous solution was determined and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, mass, 1H NMR, IR, electronic spectral and cyclic voltammetric studies. The electronic spectrum of this system showed a dependence that may be consistent with the formation of stable complexes and coordination behaviour of the ions. ESR spectra of all the complexes are recorded in solid as well as solution, which show the oxidation state of the manganese(II). Spin Hamiltonian manganese(II), which can be defined as the magnetic field vector (ℋ): ℋ=gβHS+DSz2-{35}/{12}+E[Sz2-Sy2]+ASI+ 1/6 a Sx4+Sy4+Sz4-{707}/{16}+ 1/180 F{35Sz2-475}/{2Sz2+3255/10} Significant distortion of the manganese(II) ion in observed geometry is evident from the angle subtended by the different membered chelate rings and the angles spanned by trans donor atoms octahedral geometry. Cyclic voltammetric studies indicate that complexes with all ligands undergoes one electron oxidation from manganese(II) to manganese(III) followed by a further oxidation to manganese(IV) at a significantly more positive potential.

  19. Spectroscopic constants and potential energy curves for TaH

    NASA Astrophysics Data System (ADS)

    Cheng, W.; Balasubramanian, K.

    1991-09-01

    Spectroscopic constants and potential energy curves of 21 electronic states of the diatomic TaH are computed using complete active space multiconfiguration self-consistent field (CASSCF) followed by second-order configuration interaction (SOCI) calculations. In addition spin-orbit effects were included using the relativistic configuration interaction method (RCI). The ground state of TaH was found to be a 0 + state, which is a mixture of 5Δ(0 +), 5Π(0 +), 3Σ -(0 +), and 3Π(0 +). The spin-orbit effects were found to be significant for TaH. Several spectroscopic transitions are predicted for TaH none of which is observed.

  20. Controlled spatial separation of spins and coherent dynamics in spin-orbit-coupled nanostructures

    NASA Astrophysics Data System (ADS)

    Lo, Shun-Tsung; Chen, Chin-Hung; Fan, Ju-Chun; Smith, L. W.; Creeth, G. L.; Chang, Che-Wei; Pepper, M.; Griffiths, J. P.; Farrer, I.; Beere, H. E.; Jones, G. A. C.; Ritchie, D. A.; Chen, Tse-Ming

    2017-07-01

    The spatial separation of electron spins followed by the control of their individual spin dynamics has recently emerged as an essential ingredient in many proposals for spin-based technologies because it would enable both of the two spin species to be simultaneously utilized, distinct from most of the current spintronic studies and technologies wherein only one spin species could be handled at a time. Here we demonstrate that the spatial spin splitting of a coherent beam of electrons can be achieved and controlled using the interplay between an external magnetic field and Rashba spin-orbit interaction in semiconductor nanostructures. The technique of transverse magnetic focusing is used to detect this spin separation. More notably, our ability to engineer the spin-orbit interactions enables us to simultaneously manipulate and probe the coherent spin dynamics of both spin species and hence their correlation, which could open a route towards spintronics and spin-based quantum information processing.

  1. Controlled spatial separation of spins and coherent dynamics in spin-orbit-coupled nanostructures.

    PubMed

    Lo, Shun-Tsung; Chen, Chin-Hung; Fan, Ju-Chun; Smith, L W; Creeth, G L; Chang, Che-Wei; Pepper, M; Griffiths, J P; Farrer, I; Beere, H E; Jones, G A C; Ritchie, D A; Chen, Tse-Ming

    2017-07-10

    The spatial separation of electron spins followed by the control of their individual spin dynamics has recently emerged as an essential ingredient in many proposals for spin-based technologies because it would enable both of the two spin species to be simultaneously utilized, distinct from most of the current spintronic studies and technologies wherein only one spin species could be handled at a time. Here we demonstrate that the spatial spin splitting of a coherent beam of electrons can be achieved and controlled using the interplay between an external magnetic field and Rashba spin-orbit interaction in semiconductor nanostructures. The technique of transverse magnetic focusing is used to detect this spin separation. More notably, our ability to engineer the spin-orbit interactions enables us to simultaneously manipulate and probe the coherent spin dynamics of both spin species and hence their correlation, which could open a route towards spintronics and spin-based quantum information processing.

  2. Application of Spectroscopic Techniques (FT-IR, 13C NMR) to the analysis of humic substances in volcanic soils along an environmental gradient (Tenerife, Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Rodriguez Rodriguez, Antonio; María Armas Herrera, Cecilia; González Pérez, José Antonio; González-Vila, Francisco Javier; Arbelo Rodríguez, Carmen Dolores; Mora Hernández, Juan Luis; Polvillo Polo, Oliva

    2010-05-01

    Andosols and andic soils are considered as efficient C-sinks in terms of C sequestration. These soils are usually developed from volcanic materials, and are characterized by a predominance of short-range ordered minerals like allophanes, imogolite and other Fe and Al oxyhydroxides. Such materials occur commonly associated with organic compounds, thus generating highly stable organo-mineral complexes and leading to the accumulation of a high amount of organic carbon. Spectroscopic methods like FT-IR and 13C NMR are suitable for the analysis of the chemical structure of soil humic substances, and allow identifying distinct functional groups and protein, lipids, lignin, carbohydrate-derived fragments. In this work we study the structural features of four soils developed on Pleistocene basaltic lavae in Tenerife (Canary Island, Spain), distributed along an altitudinal climatic gradient. The soil sequence comprises soils with different degree of geochemical evolution and andic character, including a mineral ‘Hypersalic Solonchak' (Tabaibal de Rasca), a slightly vitric ‘Luvic Phaeozem' (Los Frailes), a degraded and shallow ‘Endoleptic, fulvic, silandic Andosol' (Siete Lomas), and a well-developed and deep ‘Fulvic, silandic, Andosol' (Ravelo). Samples of the raw soil and humic and fulvic acids isolated from the surface horizons were analyzed. The results show a low content of organic carbon in the mineral soil, the inherited humin predominating, and a very high content of humic and fulvic acids in Andosols. The FT-IR and 13C NMR spectra of the raw soil samples show a low resolution, related to interferences from mineral complexes signals, particularly in soils with lower organic carbon content. 13C NMR shows a predominance of O-alkyl carbon (derived of carbohydrates) in andic soils, whereas O-alkyl and aromatic fractions are most evident in the mineral soil. The humic acids spectra are characterized by a dominance of alkyl and aromatic fractions with a high degree

  3. Transverse Spin Diffusion

    NASA Astrophysics Data System (ADS)

    Mullin, William

    2014-05-01

    Transverse spin diffusion is a relatively new transport coefficient and a review of its history and physical basis will be presented. In NMR spin diffusion is often measured by spin echo techniques, which involve spin currents perpendicular to the direction of the magnetization, in contrast with the usual longitudinal case where the current is parallel to the magnetization. The first indication that this involved new physics was the Leggett-Rice effect (1970) in which spin waves, new spin-echo behavior, and an altered spin diffusion coefficient were predicted in liquid 3He. This effect gave the possibility of the first measurement of F1a, the parameter of the Landau Fermi-liquid theory mean-field responsible for the effect. In 1982 Lhuillier and Laloe found a transport equation very similar to the Leggett equation, but valid for highly-polarized dilute Boltzmann Bose and Fermi gases, and describing the ``identical spin rotation effect'' (ISRE), the analog of a Landau mean field. Coincidentally Bashkin and Meyerovich had also given equivalent descriptions of transport in polarized Boltzmann gases. That a mean-field effect could exists in dilute Boltzmann gases was theoretically surprising, but was confirmed experimentally. At low polarization the basic transverse diffusion constant D⊥ coincides with the longitudinal value D∥ however Meyerovich first pointed out that they could differ in highly polarized degenerate gases. Indeed detailed calculations (Jeon and Mullin) showed that, while D∥ is proportional to T-2, D⊥ approaches a constant (depending on polarization) at low T. Considerable controversy existed until experimental verification was achieved in 2004. The importance of ISRE again arose in 2008 as the basis of ``anomalous spin-state segregation'' in Duke and JILA experiments. More recently application of the ideas of transverse spin diffusion to strongly interacting Fermi gases has resulted in the observation of the diffusion constants at the quantum

  4. Monomeric and dimeric structures analysis and spectroscopic characterization of 3,5-difluorophenylboronic acid with experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Asiri, Abdullah M.; Kurt, Mustafa

    2014-01-01

    The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C6H3F2B(OH)2) were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C NMR spectroscopic techniques. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase and 1H and 13C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200-400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. 1H and 13C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.

  5. Determination of the spin diffusion length in germanium by spin optical orientation and electrical spin injection

    NASA Astrophysics Data System (ADS)

    Rinaldi, C.; Bertoli, S.; Asa, M.; Baldrati, L.; Manzoni, C.; Marangoni, M.; Cerullo, G.; Bianchi, M.; Sordan, R.; Bertacco, R.; Cantoni, M.

    2016-10-01

    The measurement of the spin diffusion length and/or lifetime in semiconductors is a key issue for the realisation of spintronic devices, exploiting the spin degree of freedom of carriers for storing and manipulating information. In this paper, we address such parameters in germanium (0 0 1) at room temperature (RT) by three different measurement methods. Exploiting optical spin orientation in the semiconductor and spin filtering across an insulating MgO barrier, the dependence of the resistivity on the spin of photo-excited carriers in Fe/MgO/Ge spin photodiodes (spin-PDs) was electrically detected. A spin diffusion length of 0.9  ±  0.2 µm was obtained by fitting the photon energy dependence of the spin signal by a mathematical model. Electrical techniques, comprising non-local four-terminal and Hanle measurements performed on CoFeB/MgO/Ge lateral devices, led to spin diffusion lengths of 1.3  ±  0.2 µm and 1.3  ±  0.08 µm, respectively. Despite minor differences due to experimental details, the order of magnitude of the spin diffusion length is the same for the three techniques. Although standard electrical methods are the most employed in semiconductor spintronics for spin diffusion length measurements, here we demonstrate optical spin orientation as a viable alternative for the determination of the spin diffusion length in semiconductors allowing for optical spin orientation.

  6. A Comparison of FTNMR and FTIR Techniques.

    ERIC Educational Resources Information Center

    Ahn, Myong-Ku

    1989-01-01

    Nuclear magnetic resonance and infrared are two spectroscopic methods that commonly use the Fourier transform technique. Discussed are the similarities and differences in the use of the Fourier transform in these two spectroscopic techniques. (CW)

  7. A Comparison of FTNMR and FTIR Techniques.

    ERIC Educational Resources Information Center

    Ahn, Myong-Ku

    1989-01-01

    Nuclear magnetic resonance and infrared are two spectroscopic methods that commonly use the Fourier transform technique. Discussed are the similarities and differences in the use of the Fourier transform in these two spectroscopic techniques. (CW)

  8. The effect of spin transport on lifetime in nanoscale systems

    NASA Astrophysics Data System (ADS)

    Cardellino, Jeremy; Scozzaro, Nicolas; Heman, Michael; Berger, Andrew; Zhang, Chi; Fong, Kin Chung; Jayaprakash, Ciriyam; Pelekhov, Denis; Hammel, Chris; Department of Physics, P. Chris Hammel Research Team, Prof.

    2014-03-01

    Spin transport electronics utilizes electron spin as a state variable for information processing and storage. This requires manipulation of spin ensembles for data encoding, and spin transport for information transfer. Here we report spatially resolved magnetic resonance studies of electron spin ensembles confined to a quasi 1D `spin nanowire' formed by nitrogen ion implantation in diamond. We obtain the ensemble spin lifetime, that is, spin autocorrelation time, by measuring statistical fluctuations of the net moment (√N <100 net spins), which is in thermal equilibrium and has no imposed polarization gradient. We find the lifetime of the ensemble is dominated by spin transport from the ensemble into an adjacent reservoir, which is in striking contrast to conventional spin-lattice relaxation measurements of isolated spin ensembles. In addition, using a novel spin manipulation protocol, we demonstrate spectroscopic measurements on nanoscale spin ensembles that corroborate spin transport in strong field gradients. Our experiments, supported by microscopic Monte Carlo modelling, provide a unique insight into the intrinsic dynamics of charge-motion-free spin currents needed for nanoscale devices which seek to control spins.

  9. NMR in rotating magnetic fields: Magic angle field spinning

    SciTech Connect

    Sakellariou, D.; Meriles, C.; Martin, R.; Pines, A.

    2004-09-10

    Magic angle sample spinning has been one of the cornerstones in high-resolution solid state NMR. Spinning frequencies nowadays have increased by at least one order of magnitude over the ones used in the first experiments and the technique has gained tremendous popularity. It is currently a routine procedure in solid-state NMR, high-resolution liquid-state NMR and solid-state MRI. The technique enhances the spectral resolution by averaging away rank 2 anisotropic spin interactions thereby producing isotropic-like spectra with resolved chemical shifts and scalar couplings. Andrew proposed that it should be possible to induce similar effects in a static sample if the direction of the magnetic field is varied, e.g., magic-angle rotation of the B0 field (B0-MAS) and this has been recently demonstrated using electromagnetic field rotation. Here we discuss on the possibilities to perform field rotation using alternative hardware, together with spectroscopic methods to recover isotropic resolution even in cases where the field is not rotating at the magic angle. Extension to higher magnetic fields would be beneficial in situations where the physical manipulation of the sample is inconvenient or impossible. Such situations occur often in materials or biomedical samples where ''ex-situ'' NMR spectroscopy and imaging analysis is needed.

  10. XRF, μ-XRD and μ-spectroscopic techniques for revealing the composition and structure of paint layers on polychrome sculptures after multiple restorations.

    PubMed

    Franquelo, M L; Duran, A; Castaing, J; Arquillo, D; Perez-Rodriguez, J L

    2012-01-30

    This paper presents the novel application of recently developed analytical techniques to the study of paint layers on sculptures that have been restored/repainted several times across centuries. Analyses were performed using portable XRF, μ-XRD and μ-Raman instruments. Other techniques, such as optical microscopy, SEM-EDX and μ-FTIR, were also used. Pigments and other materials including vermilion, minium, red lac, ivory black, lead white, barium white, zinc white (zincite), titanium white (rutile and anatase), lithopone, gold and brass were detected. Pigments from both ancient and modern times were found due to the different restorations/repaintings carried out. μ-Raman was very useful to characterise some pigments that were difficult to determine by μ-XRD. In some cases, pigments identification was only possible by combining results from the different analytical techniques used in this work. This work is the first article devoted to the study of sculpture cross-section samples using laboratory-made μ-XRD systems. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Spin forming development

    SciTech Connect

    Gates, W.G.

    1982-05-01

    Bendix product applications require the capability of fabricating heavy gage, high strength materials. Five commercial sources have been identified that have the capability of spin forming metal thicknesses greater than 9.5 mm and four equiment manufacturers produce machines with this capability. Twelve assemblies selected as candidates for spin forming applications require spin forming of titanium, 250 maraging steel, 17-4 pH stainless steel, Nitronic 40 steel, 304 L stainless steel, and 6061 aluminum. Twelve parts have been cold spin formed from a 250 maraging steel 8.1 mm wall thickness machine preform, and six have been hot spin formed directly from 31.8-mm-thick flat plate. Thirty-three Ti-6Al-4V titanium alloy parts and 26 17-4 pH stainless steel parts have been hot spin formed directly from 31.8-mm-thick plate. Hot spin forming directly from plate has demonstrated the feasibility and favorable economics of this fabrication technique for Bendix applications.

  12. Spin forming development

    NASA Astrophysics Data System (ADS)

    Gates, W. G.

    1982-05-01

    Bendix product applications require the capability of fabricating heavy gage, high strength materials. Five commercial sources have been identified that have the capability of spin forming metal thicknesses greater than 9.5 mm and four equipment manufacturers produce machines with this capability. Twelve assemblies selected as candidates for spin forming applications require spin forming of titanium, 250 maraging steel, 17-4 pH stainless steel, Nitronic 40 steel, 304 L stainless steel, and 6061 aluminum. Twelve parts have been cold spin formed from a 250 maraging steel 8.1 mm wall thickness machine preform, and six have been hot spin formed directly from 31.8-mm-thick flat plate. Thirty-three Ti-6Al-4V titanium alloy parts and 26 17-4 pH stainless steel parts have been hot spin formed directly from 31.8-mm-thick plate. Hot spin forming directly from plate has demonstrated the feasibility and favorable economics of this fabrication technique for Bendix applications.

  13. Robust spin-current injection in lateral spin valves with two-terminal Co2FeSi spin injectors

    NASA Astrophysics Data System (ADS)

    Oki, S.; Kurokawa, T.; Honda, S.; Yamada, S.; Kanashima, T.; Itoh, H.; Hamaya, K.

    2017-05-01

    We demonstrate generation and detection of pure spin currents by combining a two-terminal spin-injection technique and Co2FeSi (CFS) spin injectors in lateral spin valves (LSVs). We find that the two-terminal spin injection with CFS has the robust dependence of the nonlocal spin signals on the applied bias currents, markedly superior to the four-terminal spin injection with permalloy reported previously. In our LSVs, since the spin transfer torque from one CFS injector to another CFS one is large, the nonlocal magnetoresistance with respect to applied magnetic fields shows large asymmetry in high bias-current conditions. For utilizing multi-terminal spin injection with CFS as a method for magnetization reversals, the terminal arrangement of CFS spin injectors should be taken into account.

  14. Characterization of spin relaxation anisotropy in Co using spin pumping

    NASA Astrophysics Data System (ADS)

    Li, Yi; Cao, Wei; Bailey, W. E.

    2016-11-01

    Ferromagnets are believed to exhibit strongly anisotropic spin relaxation, with relaxation lengths for spin longitudinal to the magnetization significantly longer than those for spin transverse to the magnetization. Here, we characterize the anisotropy of spin relaxation in Co using the spin pumping contribution to Gilbert damping in noncollinearly magnetized Py1 -xCux /Cu/Co trilayer structures. The static magnetization angle between Py1 -xCux and Co, adjusted under field bias perpendicular to film planes, controls the projections of longitudinal and transverse spin current pumped from Py1 -xCux into Co. We find nearly isotropic absorption of pure spin current in Co using this technique; fits to a diffusive transport model yield the longitudinal spin relaxation length <2 nm in Co. The longitudinal spin relaxation lengths found are an order of magnitude smaller than those determined by current-perpendicular-to-planes giant magnetoresistance measurements, but comparable with transverse spin relaxation lengths in Co determined by spin pumping.

  15. Chelating fibers prepared with a wet spinning technique using a mixture of a viscose solution and a polymer ligand for the separation of metal ions in an aqueous solution.

    PubMed

    Kagaya, Shigehiro; Miyazaki, Hiroyuki; Inoue, Yoshinori; Kato, Toshifumi; Yanai, Hideyuki; Kamichatani, Waka; Kajiwara, Takehiro; Saito, Mitsuru; Tohda, Koji

    2012-02-15

    Chelating fibers containing polymer ligands such as carboxymethylated polyallylamine, carboxymethylated polyethyleneimine, and a copolymer of diallylamine hydrochloride/maleic acid were prepared with a wet spinning technique using mixtures of a viscose solution and the polymer ligands. The chelating fibers obtained effectively adsorbed various metal ions, including Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), Ti(IV), and Zn(II). The metal ions adsorbed could be readily desorbed using 0.1 or 0.5 mol L(-1) HNO(3). The chelating fiber containing carboxymethylated polyallylamine was available for the separation of some metal ions in synthetic wastewater containing a large amount of Na(2)SO(4). The wet spinning technique using a solution containing a base polymer and a polymer ligand was quite simple and effective and would be applicable for preparing various chelating fibers.

  16. Arterial Spin-Labeled Perfusion Combined with Segmentation Techniques to Evaluate Cerebral Blood Flow in White and Gray Matter of Children with Sickle Cell Anemia

    PubMed Central

    Helton, Kathleen J.; Paydar, Amir; Glass, John; Weirich, Eric M.; Hankins, Jane; Li, Chin-Shang; Smeltzer, Matthew P.; Wang, Winfred C.; Ware, Russell E.; Ogg, Robert J.

    2015-01-01

    Background Changes in cerebral perfusion are an important feature of the pathophysiology of sickle cell anemia (SCA); cerebrovascular ischemia occurs frequently and leads to neurocognitive deficits, silent infarcts, and overt stroke. Non-invasive MRI methods to measure cerebral blood flow (CBF) by arterial spin labeling (ASL) afford new opportunities to characterize disease- and therapy-induced changes in cerebral hemodynamics in patients with SCA. Recent studies have documented elevated gray matter (GM) CBF in untreated children with SCA, but no measurements of white matter (WM) CBF have been reported. Procedures Pulsed ASL with automated brain image segmentation-classification techniques were used to determine the CBF in GM, WM, and abnormal white matter (ABWM) of 21 children with SCA, 18 of whom were receiving hydroxyurea therapy. Results GM and WM CBF were highly associated (R2 =.76, p< 0.0001) and the GM to WM CBF ratio was 1.6 (95% confidence interval: 1.43-1.83). Global GM CBF in our treated cohort was 87 ± 24 mL/min/100 g, a value lower than previously reported in untreated patients with SCA. CBF was elevated in normal appearing WM (43 ± 14 mL/min/100 g) but decreased in ABWM (6 ± 12 mL/min/100 g), compared to published normal pediatric controls. Hemispheric asymmetry in CBF was noted in most patients. Conclusions These perfusion measurements suggest that hydroxyurea may normalize GM CBF in children with SCA, but altered perfusion in WM may persist. This novel combined approach for CBF quantification will facilitate prospective studies of cerebral vasculopathy in SCA, particularly regarding the effects of treatments such as hydroxyurea. PMID:18937311

  17. Nuclear spin effects in semiconductor quantum dots.

    PubMed

    Chekhovich, E A; Makhonin, M N; Tartakovskii, A I; Yacoby, A; Bluhm, H; Nowack, K C; Vandersypen, L M K

    2013-06-01

    The interaction of an electronic spin with its nuclear environment, an issue known as the central spin problem, has been the subject of considerable attention due to its relevance for spin-based quantum computation using semiconductor quantum dots. Independent control of the nuclear spin bath using nuclear magnetic resonance techniques and dynamic nuclear polarization using the central spin itself offer unique possibilities for manipulating the nuclear bath with significant consequences for the coherence and controlled manipulation of the central spin. Here we review some of the recent optical and transport experiments that have explored this central spin problem using semiconductor quantum dots. We focus on the interaction between 10(4)-10(6) nuclear spins and a spin of a single electron or valence-band hole. We also review the experimental techniques as well as the key theoretical ideas and the implications for quantum information science.

  18. The role of chromatographic and chiroptical spectroscopic techniques and methodologies in support of drug discovery for atropisomeric drug inhibitors of Bruton's tyrosine kinase.

    PubMed

    Dai, Jun; Wang, Chunlei; Traeger, Sarah C; Discenza, Lorell; Obermeier, Mary T; Tymiak, Adrienne A; Zhang, Yingru

    2017-03-03

    Atropisomers are stereoisomers resulting from hindered bond rotation. From synthesis of pure atropisomers, characterization of their interconversion thermodynamics to investigation of biological stereoselectivity, the evaluation of drug candidates subject to atropisomerism creates special challenges and can be complicated in both early drug discovery and later drug development. In this paper, we demonstrate an array of analytical techniques and systematic approaches to study the atropisomerism of drug molecules to meet these challenges. Using a case study of Bruton's tyrosine kinase (BTK) inhibitor drug candidates at Bristol-Myers Squibb, we present the analytical strategies and methodologies used during drug discovery including the detection of atropisomers, the determination of their relative composition, the identification of relative chirality, the isolation of individual atropisomers, the evaluation of interconversion kinetics, and the characterization of chiral stability in the solid state and in solution. In vivo and in vitro stereo-stability and stereo-selectivity were investigated as well as the pharmacological significance of any changes in atropisomer ratios. Techniques applied in these studies include analytical and preparative enantioselective supercritical fluid chromatography (SFC), enantioselective high performance liquid chromatography (HPLC), circular dichroism (CD), and mass spectrometry (MS). Our experience illustrates how atropisomerism can be a very complicated issue in drug discovery and why a thorough understanding of this phenomenon is necessary to provide guidance for pharmaceutical development. Analytical techniques and methodologies facilitate key decisions during the discovery of atropisomeric drug candidates by characterizing time-dependent physicochemical properties that can have significant biological implications and relevance to pharmaceutical development plans. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Novel, near-infrared spectroscopic, label-free, techniques to assess bone abnormalities such as Paget's disease, osteoporosis and bone fractures

    NASA Astrophysics Data System (ADS)

    Sordillo, Diana C.; Sordillo, Laura A.; Shi, Lingyan; Budansky, Yury; Sordillo, Peter P.; Alfano, Robert R.

    2015-02-01

    Near- infrared (NIR) light with wavelengths from 650 nm to 950 nm (known as the first NIR window) has conventionally been used as a non-invasive technique that can reach deeper penetration depths through media than light at shorter wavelengths. Recently, several novel, NIR, label-free, techniques have been developed to assess Paget's disease of bone, osteoporosis and bone microfractures. We designed a Bone Optical Analyzer (BOA) which utilizes the first window to measure changes of Hb and HbO2. Paget's disease is marked by an increase in vascularization in bones, and this device can enable easy diagnosis and more frequent monitoring of the patient's condition, without exposing him to a high cumulative dose of radiation. We have also used inverse imaging algorithms to reconstruct 2D and 3D maps of the bone's structure. This device could be used to assess diseases such as osteoporosis. Using 800 nm femtosecond excitation with two-photon (2P) microscopy, we acquired 2PM images of the periosteum and spatial frequency spectra (based on emission of collagen) from the periosteal regions. This technique can provide information on the structure of the periosteum and can detect abnormalities which may be an indication of disease. Most recently, we showed that longer NIR wavelengths in the second and third NIR windows (1100 nm-1350 nm, 1600 nm-1870 nm), could be used to image bone microfractures. Use of NIR light could allow for repeated studies in patients with diseases such as Paget's and osteoporosis quickly and non-invasively, and could impact the current management for these diseases.

  20. Quantification of myocardial blood flow and flow reserve in rats using arterial spin labeling MRI: comparison with a fluorescent microsphere technique.

    PubMed

    Jacquier, Alexis; Kober, Frank; Bun, Soksithikun; Giorgi, Roch; Cozzone, Patrick J; Bernard, Monique

    2011-11-01

    To quantify noninvasively myocardial blood flow (MBF) and MBF reserve in isoflurane-anesthetized rats using the Look-Locker flow-alternating inversion recovery gradient-echo arterial spin labeling technique (LLFAIRGE-ASL), and to compare the results with the fluorescent microsphere (FM) technique. Male Wistar rats (weight = 200-240 g, n = 21) were anesthetized with 2.0% isoflurane. Hemodynamic parameters were recorded. In seven rats, MBF was assessed on a Bruker Biospec 4.7T MR system using an ECG- and respiration-gated LLFAIRGE-ASL (pixel size = 234 × 468µm(2) , TE = 1.52ms) at rest and during adenosine infusion (140 µg/kg/min). A mixture of 200 000 FM was injected into a second group of rats at rest and during adenosine infusion (n = 7 each), under similar physiologic conditions. Hearts and skeletal muscle samples were processed for fluorescence spectroscopy. Two-tailed unpaired, paired Student's t-test and ANOVA were used to compare groups. MBF measured with LLFAIRGE-ASL was 5.2 ± 1.0 mL/g/min at rest and 13.3 ± 3.0 mL/g/min during adenosine infusion. Results obtained with fluorescent microspheres yielded 5.9 ± 2.3 mL/g/min (nonsignificant vs. LLFAIRGE-ASL, p = 0.9) at rest and 13.1 ± 2.1 mL/g/min (nonsignificant vs. LLFAIRGE-ASL, p = 0.4) during adenosine infusion. Myocardial blood flow reserve measured using LLFAIRGE-ASL and FM were not significantly different (2.5 ± 0.6 vs. 2.4 ± 0.9, respectively; p = 0.8). Hemodynamic parameters during the experiments were not different between the groups. The myocardial blood flow reserve determined under isoflurane anesthesia was 2.5 ± 0.6, which was not different from the value obtained with FM. LLFAIRGE-ASL provided MBF maps with high spatial resolution in rats under isoflurane anesthesia. LLFAIRGE-ASL is a noninvasive measure to assess myocardial blood flow reserve and provides an interesting tool for cardiovascular research

  1. Spectroscopic optical coherence elastography.

    PubMed

    Adie, Steven G; Liang, Xing; Kennedy, Brendan F; John, Renu; Sampson, David D; Boppart, Stephen A

    2010-12-06

    We present an optical technique to image the frequency-dependent complex mechanical response of a viscoelastic sample. Three-dimensional hyperspectral data, comprising two-dimensional B-mode images and a third dimension corresponding to vibration frequency, were acquired from samples undergoing external mechanical excitation in the audio-frequency range. We describe the optical coherence tomography (OCT) signal when vibration is applied to a sample and detail the processing and acquisition techniques used to extract the local complex mechanical response from three-dimensional data that, due to a wide range of vibration frequencies, possess a wide range of sample velocities. We demonstrate frequency-dependent contrast of the displacement amplitude and phase of a silicone phantom containing inclusions of higher stiffness. Measurements of an ex vivo tumor margin demonstrate distinct spectra between adipose and tumor regions, and images of displacement amplitude and phase demonstrated spatially-resolved contrast. Contrast was also observed in displacement amplitude and phase images of a rat muscle sample. These results represent the first demonstration of mechanical spectroscopy based on B-mode OCT imaging. Spectroscopic optical coherence elastography (S-OCE) provides a high-resolution imaging capability for the detection of tissue pathologies that are characterized by a frequency-dependent viscoelastic response.

  2. Elemental and spectroscopic characterization of plasters from Fatih Mosque-Istanbul (Turkey) by combined micro-Raman, FTIR and EDXRF techniques.

    PubMed

    Akyuz, Tanil; Akyuz, Sevim; Gulec, Ahmet

    2015-10-05

    The characterization of the plasters and coloring agents of the wall paintings of Fatih Mosque have been performed using combined micro-Raman, FTIR and EDXRF techniques. The investigations show that the plaster used on the walls has mixed gypsum-lime binders. Cinnabar {HgS}, lead red {Pb3O4} and hematite {α-Fe2O3} were identified in the red surfaces. Blue color is attributed to ultramarine blue {Na8-10Al6Si6O24S2-4}. Green color is assigned to mixtures of green earth, copper phthalocyanine {Cu(C32Cl16N8)} and brochantite {CuSO4·3Cu(OH)2}. Strontium yellow {SrCrO4} and zinc white {ZnO} were also used to ensure the color tone. The results provide a basis for future restoration of wall paints. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Spin-orbit-coupling-induced spin squeezing in three-component Bose gases

    NASA Astrophysics Data System (ADS)

    Huang, X. Y.; Sun, F. X.; Zhang, W.; He, Q. Y.; Sun, C. P.

    2017-01-01

    We observe spin squeezing in three-component Bose gases where all three hyperfine states are coupled by synthetic spin-orbit coupling. This phenomenon is a direct consequence of spin-orbit coupling, as can be seen clearly from an effective spin Hamiltonian. By solving this effective model analytically with the aid of a Holstein-Primakoff transformation for a spin-1 system in the low excitation limit, we conclude that the spin-nematic squeezing, a category of spin squeezing existing exclusively in large spin systems, is enhanced with increasing spin-orbit coupling intensity and effective Zeeman field, which correspond to Rabi frequency ΩR and two-photon detuning δ within the Raman scheme for synthetic spin-orbit coupling, respectively. These trends of dependence are in clear contrast to spin-orbit-coupling-induced spin squeezing in spin-1/2 systems. We also analyze the effects of harmonic trap and interparticle interaction with realistic experimental parameters numerically, and find that a strong harmonic trap favors spin-nematic squeezing. We further show spin-nematic squeezing can be interpreted as two-mode entanglement or two-spin squeezing at low excitation. Our findings can be observed in 87Rb gases with existing techniques of synthetic spin-orbit coupling and spin-selective imaging.

  4. Optical Spectroscopic Monitoring of Parachute Yarn Aging

    SciTech Connect

    Tallant, D.R.; Garcia, M.J.; Simpson, R.L.; Behr, V.L.; Whinery, L.D.; Peng, L.W.

    1999-04-01

    Optical spectroscopic techniques were evaluated as nondestructive monitors of the aging of parachutes in nuclear weapons. We analyzed thermally aged samples of nylon and Kevlar webbing by photoluminescence spectroscopy and reflection spectroscopy. Infrared analysis was also performed to help understand the degradation mechanisms of the polymer materials in the webbing. The photoluminescence and reflection spectra were analyzed by chemometric data treatment techniques to see if aged-induced changes in the spectra correlated to changes in measured tensile strength. A correlation was found between the shapes of the photoluminescent bands and the measured tensile strengths. Photoluminescent spectra can be used to predict the tensile strengths of nylon and Kevlar webbing with sufficient accuracy to categorize the webbing sample as above rated tensile strength, marginal or below rated tensile strength. The instrumentation required to perform the optical spectroscopic measurement can be made rugged, compact and portable. Thus, optical spectroscopic techniques offer a means for nondestructive field monitoring of parachutes in the enduring stockpile/

  5. In vitro studies on the behavior of salmeterol xinafoate and its interaction with calf thymus DNA by multi-spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Zhao, Tingting; Bi, Shuyun; Wang, Yu; Wang, Tianjiao; Pang, Bo; Gu, Tingting

    2014-11-01

    The salmeterol xinafoate (SX) binding to calf thymus DNA in vitro was explored by fluorescence, resonance light scattering (RLS), UV-vis absorption, as well as viscometry, ionic strength effect and DNA melting techniques. It was found that SX could bind to DNA weakly, and the binding constants (Ka) were determined as 8.52 × 103, 8.31 × 103 and 6.14 × 103 L mol-1 at 18, 28 and 38 °C respectively. When bound to DNA, SX showed fluorescence quenching in the fluorescence spectra and hyperchromic effect in the absorption spectra. Stern-Volmer plots revealed that the quenching of fluorescence of SX by DNA was a static quenching. Furthermore, the relative viscosity and melting temperature of DNA solution were hardly influenced by SX, while the fluorescence intensity of SX-DNA was observed to decrease with the increasing ionic strength of system. Also, the binding constant between SX and double stranded DNA (dsDNA) was much weaker than that between SX and single stranded DNA (ssDNA). All these results suggested that the binding mode of SX to DNA should be groove binding. The obtained thermodynamic parameters indicated that electrostatic force might play a predominant role in SX binding to DNA. The quantum yield (φ) of SX was measured as 0.13 using comparative method. Based on the Förster resonance energy transfer theory (FRET), the binding distance (r0) between the acceptor and donor was calculated as 4.10 nm.

  6. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques

    PubMed Central

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-01-01

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation assay, the binding sites of MLN8237 were validated through two site-specific spy molecules (warfarin sodium and ibuprofen, which are two known site-selective probes) by using STD and WaterLOGSY NMR competition techniques. These competition experiments demonstrate that both spy molecules do not compete with MLN8237 for the specific binding site. The AutoDock-based blind docking study recognizes the hydrophobic subdomain IB of the protein as the probable binding site for MLN8237. Thermodynamic investigations by isothermal titration calorimetry (ITC) reveal that the non-covalent interaction between MLN8237 and HSA (binding constant was approximately 105 M−1) is driven mainly by favorable entropy and unfavorable enthalpy. In addition, synchronous fluorescence, circular dichroism (CD), and 3D fluorescence spectroscopy suggest that MLN8237 may induce conformational changes in HSA. PMID:28358124

  7. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques

    NASA Astrophysics Data System (ADS)

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-03-01

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation assay, the binding sites of MLN8237 were validated through two site-specific spy molecules (warfarin sodium and ibuprofen, which are two known site-selective probes) by using STD and WaterLOGSY NMR competition techniques. These competition experiments demonstrate that both spy molecules do not compete with MLN8237 for the specific binding site. The AutoDock-based blind docking study recognizes the hydrophobic subdomain IB of the protein as the probable binding site for MLN8237. Thermodynamic investigations by isothermal titration calorimetry (ITC) reveal that the non-covalent interaction between MLN8237 and HSA (binding constant was approximately 105 M-1) is driven mainly by favorable entropy and unfavorable enthalpy. In addition, synchronous fluorescence, circular dichroism (CD), and 3D fluorescence spectroscopy suggest that MLN8237 may induce conformational changes in HSA.

  8. Thermal inkjet application in the preparation of oral dosage forms: dispensing of prednisolone solutions and polymorphic characterization by solid-state spectroscopic techniques.

    PubMed

    Meléndez, Peter A; Kane, Kevin M; Ashvar, Claudine S; Albrecht, Mary; Smith, Pamela A

    2008-07-01

    The utility of thermal inkjet (TIJ) technology for preparing solid dosage forms of drugs was examined. Solutions of prednisolone in a solvent mixture of ethanol, water, and glycerol (80/17/3 by volume) were dispensed onto poly(tetrafluoroethylene)-coated fiberglass films using TIJ cartridges and a personal printer and using a micropipette for comparison. The post-dried, TIJ-dispensed samples were shown to contain a mixture of prednisolone Forms I and III based on PXRD analyses that were confirmed by Raman analyses. The starting commercial material was determined to be Form I. Samples prepared by dispensing the solution from a micropipette initially showed only Form I; subsequent Raman mapping of these samples revealed the presence of two polymorphs. Raman mapping of the TIJ-dispensed samples also showed both polymorphs. The results indicate that the solvent mixture used in the dispensing solution combined with the thermal treatment of the samples after dispensing were likely the primary reason for the generation of the two polymorphs. The advantages of using a multidisciplinary approach to characterize drug delivery systems are demonstrated using solid state mapping techniques. Both PXRD and Raman spectroscopy were needed to fully characterize the samples. Finally, this report clarifies prednisolone's polymorphic nomenclature existent in the scientific literature.

  9. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques.

    PubMed

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-03-30

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation assay, the binding sites of MLN8237 were validated through two site-specific spy molecules (warfarin sodium and ibuprofen, which are two known site-selective probes) by using STD and WaterLOGSY NMR competition techniques. These competition experiments demonstrate that both spy molecules do not compete with MLN8237 for the specific binding site. The AutoDock-based blind docking study recognizes the hydrophobic subdomain IB of the protein as the probable binding site for MLN8237. Thermodynamic investigations by isothermal titration calorimetry (ITC) reveal that the non-covalent interaction between MLN8237 and HSA (binding constant was approximately 10(5) M(-1)) is driven mainly by favorable entropy and unfavorable enthalpy. In addition, synchronous fluorescence, circular dichroism (CD), and 3D fluorescence spectroscopy suggest that MLN8237 may induce conformational changes in HSA.

  10. Spin noise in the anisotropic central spin model

    NASA Astrophysics Data System (ADS)

    Hackmann, Johannes; Anders, Frithjof B.

    2014-01-01

    Spin-noise measurements can serve as a direct probe for the microscopic decoherence mechanism of an electronic spin in semiconductor quantum dots (QDs). We have calculated the spin-noise spectrum in the anisotropic central spin model using a Chebyshev expansion technique which exactly accounts for the dynamics up to an arbitrary long but fixed time in a finite-size system. In the isotropic case, describing QD charge with a single electron, the short-time dynamics is in good agreement with quasistatic approximations for the thermodynamic limit. The spin-noise spectrum, however, shows strong deviations at low frequencies with a power-law behavior of ω-3/4 corresponding to a t-1/4 decay at intermediate and long times. In the Ising limit, applicable to QDs with heavy-hole spins, the spin-noise spectrum exhibits a threshold behavior of (ω-ωL)-1/2 above the Larmor frequency ωL=gμBB. In the generic anisotropic central spin model we have found a crossover from a Gaussian type of spin-noise spectrum to a more Ising-type spectrum with increasing anisotropy in a finite magnetic field. In order to make contact with experiments, we present ensemble averaged spin-noise spectra for QD ensembles charged with single electrons or holes. The Gaussian-type noise spectrum evolves to a more Lorentzian shape spectrum with increasing spread of characteristic time scales and g factors of the individual QDs.

  11. Spectroscopic characterization of III-V semiconductor nanomaterials

    NASA Astrophysics Data System (ADS)

    Crankshaw, Shanna Marie

    through a novel spectroscopic technique first formulated for the rather different purpose of dispersion engineering for slow-light schemes. The frequency-resolved technique combined with the unusual (110) quantum wells in a furthermore atypical waveguide experimental geometry has revealed fascinating behavior of electron spin splitting which points to the possibility of optically orienting electron spins with linearly polarized light---an experimental result supporting a theoretical description of the phenomenon itself only a few years old. Lastly, to explore a space of further-restricted dimensionality, the final chapters describe InP semiconductor nanowires with dimensions small enough to be considered truly one-dimensional. Like the bulk GaAs of the first few chapters, the InP nanowires here crystallize in a wurtzite structure. In the InP nanowire case, though, the experimental techniques explored for characterization are temperature-dependent time-integrated photoluminescence at the single-wire level (including samples with InAsP insertions) and time-resolved photoluminescence at the ensemble level. The carrier dynamics revealed through these time-resolved studies are the first of their kind for wurtzite InP nanowires. The chapters are thus ordered as a progression from three (bulk), to two (quantum well), to one (nanowire), to zero dimensions (axially-structured nanowire), with the uniting theme the emphasis on connecting the semiconductor nanomaterials' crystallinity to its exhibited properties by relevant experimental spectroscopic techniques, whether these are standard methods or effectively invented for the case at hand.

  12. A new combined nuclear magnetic resonance and Raman spectroscopic probe applied to in situ investigations of catalysts and catalytic processes

    SciTech Connect

    Camp, Jules C. J.; Mantle, Michael D.; York, Andrew P. E.; McGregor, James

    2014-06-15

    Both Raman and nuclear magnetic resonance (NMR) spectroscopies are valuable analytical techniques capable of providing mechanistic information and thereby providing insights into chemical processes, including catalytic reactions. Since both techniques are chemically sensitive, they yield not only structural information but also quantitative analysis. In this work, for the first time, the combination of the two techniques in a single experimental apparatus is reported. This entailed the design of a new experimental probe capable of recording simultaneous measurements on the same sample and/or system of interest. The individual datasets acquired by each spectroscopic method are compared to their unmodified, stand-alone equivalents on a single sample as a means to benchmark this novel piece of equipment. The application towards monitoring reaction progress is demonstrated through the evolution of the homogeneous catalysed metathesis of 1‑hexene, with both experimental techniques able to detect reactant consumption and product evolution. This is extended by inclusion of magic angle spinning (MAS) NMR capabilities with a custom made MAS 7 mm rotor capable of spinning speeds up to 1600 Hz, quantified by analysis of the spinning sidebands of a sample of KBr. The value of this is demonstrated through an application involving heterogeneous catalysis, namely the metathesis of 2-pentene and ethene. This provides the added benefit of being able to monitor both the reaction progress (by NMR spectroscopy) and also the structure of the catalyst (by Raman spectroscopy) on the very same sample, facilitating the development of structure-performance relationships.

  13. A new combined nuclear magnetic resonance and Raman spectroscopic probe applied to in situ investigations of catalysts and catalytic processes

    NASA Astrophysics Data System (ADS)

    Camp, Jules C. J.; Mantle, Michael D.; York, Andrew P. E.; McGregor, James

    2014-06-01

    Both Raman and nuclear magnetic resonance (NMR) spectroscopies are valuable analytical techniques capable of providing mechanistic information and thereby providing insights into chemical processes, including catalytic reactions. Since both techniques are chemically sensitive, they yield not only structural information but also quantitative analysis. In this work, for the first time, the combination of the two techniques in a single experimental apparatus is reported. This entailed the design of a new experimental probe capable of recording simultaneous measurements on the same sample and/or system of interest. The individual datasets acquired by each spectroscopic method are compared to their unmodified, stand-alone equivalents on a single sample as a means to benchmark this novel piece of equipment. The application towards monitoring reaction progress is demonstrated through the evolution of the homogeneous catalysed metathesis of 1-hexene, with both experimental techniques able to detect reactant consumption and product evolution. This is extended by inclusion of magic angle spinning (MAS) NMR capabilities with a custom made MAS 7 mm rotor capable of spinning speeds up to 1600 Hz, quantified by analysis of the spinning sidebands of a sample of KBr. The value of this is demonstrated through an application involving heterogeneous catalysis, namely the metathesis of 2-pentene and ethene. This provides the added benefit of being able to monitor both the reaction progress (by NMR spectroscopy) and also the structure of the catalyst (by Raman spectroscopy) on the very same sample, facilitating the development of structure-performance relationships.

  14. Structure, morphology and Raman and optical spectroscopic analysis of In1-xCuxP thin films grown by MOCVD technique for solar cell applications

    NASA Astrophysics Data System (ADS)

    Alshahrie, Ahmed; Juodkazis, S.; Al-Ghamdi, A. A.; Hafez, M.; Bronstein, L. M.

    2017-10-01

    Nanocrystalline In1-xCuxP thin films (0 ≤ x ≤ 0.5) have been deposited on quartz substrates by a Metal-Organic Chemical Vapor Deposition (MOCVD) technique. The effect of the copper ion content on the structural crystal lattice, morphology and optical behavior of the InP thin films was assessed using X-ray diffraction, scanning electron microscopy, atomic force microscopy, Raman spectroscopy and spectrophotometry. All films exhibited a crystalline cubic zinc blende structure, inferring the solubility of the Cu atoms in the InP crystal structure. The XRD patterns demonstrated that the inclusion of Cu atoms into the InP films forced the nanoparticles in the films to grow along the (1 1 1) direction. The AFM topography showed that the Cu ions reduce the surface roughness of deposited films. The Raman spectra of the deposited films contain the first and second order anti-stoke ΓTO, ΓLO, ΧLO + ΧTO, 2ΓTO, and ΓLO + ΓTO bands which are characteristic of the InP crystalline structure. The intensities of these bands decreased with increasing the content of the Cu atoms in the InP crystals implying the creation of a stacking fault density in the InP crystal structure. The In1-xCuxP thin films have shown high optical transparency of 90%. An increase of the optical band gap from 1.38 eV to 1.6 eV was assigned to the increase of the amount of Cu ions in the InP films. The In0.5Cu0.5P thin film exhibited remarkable optical conductivity with very low dissipation factor which makes it a promising buffer window for solar energy applications.

  15. Trans fat labeling and levels in U.S. foods: assessment of gas chromatographic and infrared spectroscopic techniques for regulatory compliance.

    PubMed

    Mossoba, Magdi M; Moss, Julie; Kramer, John K G

    2009-01-01

    Trans fatty acids are found in a variety of foods like dairy and meat products, but the major dietary sources are products that contain commercially hydrogenated fats. There has been a renewed need for accurate analytical methods for the quantitation of total trans fat since mandatory requirements to declare the amount of trans fat present in food products and dietary supplements were issued in many countries. Official capillary GC and IR methodologies are the two most common validated methods used to identify and quantify trans fatty acids for regulatory compliance. The present article provides a comprehensive discussion of the GC and IR techniques, including the latest attenuated total reflection (ATR)-FTIR methodology called the negative second derivative ATR-FTIR procedure, which is currently being validated in an international collaborative study. The identification and quantitation of trans fatty acid isomers by GC is reviewed and an alternative GC method is proposed using two temperature programs and combining their results; this proposed method deals more effectively with the resolution of large numbers of geometric and positional monoene, diene, and triene fatty acid isomers present in ruminant fats. In addition, the different methylation procedures that affect quantitative conversion to fatty acid methyl esters are reviewed. There is also a lack of commercial chromatographic standards for many trans fatty acid isomers. This review points to potential sources of interferences in the FTIR determination that may lead to inaccurate results, particularly at low trans levels. The presence of high levels of saturated fats may lead to interferences in the FTIR spectra observed for trans triacylglycerols (TAGs). TAGs require no derivatization, but have to be melted prior to IR measurement. While GC is currently the method of choice, ATR-FTIR spectroscopy is a viable, rapid alternative, and a complementary method to GC for a more rapid determination of total trans

  16. Characterization of the deterioration of bone black in the 17 th century Oranjezaal paintings using electron-microscopic and micro-spectroscopic imaging techniques

    NASA Astrophysics Data System (ADS)

    van Loon, Annelies; Boon, Jaap J.

    2004-10-01

    A whitish deterioration product was observed on the dark paint in a number of large-scale oil paintings that are part of the Oranjezaal interior decoration in the Royal Palace Huis ten Bosch (The Hague). The whitened areas of a painting by Pieter Soutman dating from 1648 were micro-sampled and compared with "healthy" black paint using different analytical imaging techniques. The dark paint was identified as bone black in linseed oil with a lead drier added. Microscopic images of the cross-section revealed a white top layer of 10-20 μm in the black paint layer. Imaging the cross-section surface with scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and specular reflection Fourier transform infrared (FTIR) showed homogeneous distributions of phosphate, phosphorus and calcium over the black and the white degraded bone black. X-ray diffraction (XRD) showed the presence of calcium phosphate hydrate (Ca 3(PO 4) 2· xH 2O), monetite (CaHPO 4) with possibly some poorly crystalline or amorphous hydroxyapatite (Ca 5(OH)(PO 4) 3). The EDX maps of lead and carbon, however, showed some discontinuity between the degraded and non-degraded bone black. There was an increase in the lead concentration in the white top layer, and a slight decrease of carbon. Transmission FTIR demonstrated that aromatic network polymers from the carbon black are markedly diminished in the white deterioration product. It is proposed that the carbonized organic matter in the bone black is vulnerable to photo bleaching in the presence of a lead catalyst under these circumstances.

  17. Evaluation of Aqueductal Patency in Patients with Hydrocephalus: Three-Dimensional High-Sampling-Efficiency Technique (SPACE) versus Two-Dimensional Turbo Spin Echo at 3 Tesla

    PubMed Central

    Guryildirim, Melike; Tokgoz, Nil; Kilic, Koray; Borcek, Alp; Oner, Yusuf; Akkan, Koray; Tali, Turgut

    2014-01-01

    Objective To compare the accuracy of diagnosing aqueductal patency and image quality between high spatial resolution three-dimensional (3D) high-sampling-efficiency technique (sampling perfection with application optimized contrast using different flip angle evolutions [SPACE]) and T2-weighted (T2W) two-dimensional (2D) turbo spin echo (TSE) at 3-T in patients with hydrocephalus. Materials and Methods This retrospective study included 99 patients diagnosed with hydrocephalus. T2W 3D-SPACE was added to the routine sequences which consisted of T2W 2D-TSE, 3D-constructive interference steady state (CISS), and cine phase-contrast MRI (PC-MRI). Two radiologists evaluated independently the patency of cerebral aqueduct and image quality on the T2W 2D-TSE and T2W 3D-SPACE. PC-MRI and 3D-CISS were used as the reference for aqueductal patency and image quality, respectively. Inter-observer agreement was calculated using kappa statistics. Results The evaluation of the aqueductal patency by T2W 3D-SPACE and T2W 2D-TSE were in agreement with PC-MRI in 100% (99/99; sensitivity, 100% [83/83]; specificity, 100% [16/16]) and 83.8% (83/99; sensitivity, 100% [67/83]; specificity, 100% [16/16]), respectively (p < 0.001). No significant difference in image quality between T2W 2D-TSE and T2W 3D-SPACE (p = 0.056) occurred. The kappa values for inter-observer agreement were 0.714 for T2W 2D-TSE and 0.899 for T2W 3D-SPACE. Conclusion Three-dimensional-SPACE is superior to 2D-TSE for the evaluation of aqueductal patency in hydrocephalus. T2W 3D-SPACE may hold promise as a highly accurate alternative treatment to PC-MRI for the physiological and morphological evaluation of aqueductal patency. PMID:25469096

  18. Evaluation of aqueductal patency in patients with hydrocephalus: three-dimensional high-sampling-efficiency technique (SPACE) versus two-dimensional turbo spin echo at 3 Tesla.

    PubMed

    Ucar, Murat; Guryildirim, Melike; Tokgoz, Nil; Kilic, Koray; Borcek, Alp; Oner, Yusuf; Akkan, Koray; Tali, Turgut

    2014-01-01

    To compare the accuracy of diagnosing aqueductal patency and image quality between high spatial resolution three-dimensional (3D) high-sampling-efficiency technique (sampling perfection with application optimized contrast using different flip angle evolutions [SPACE]) and T2-weighted (T2W) two-dimensional (2D) turbo spin echo (TSE) at 3-T in patients with hydrocephalus. This retrospective study included 99 patients diagnosed with hydrocephalus. T2W 3D-SPACE was added to the routine sequences which consisted of T2W 2D-TSE, 3D-constructive interference steady state (CISS), and cine phase-contrast MRI (PC-MRI). Two radiologists evaluated independently the patency of cerebral aqueduct and image quality on the T2W 2D-TSE and T2W 3D-SPACE. PC-MRI and 3D-CISS were used as the reference for aqueductal patency and image quality, respectively. Inter-observer agreement was calculated using kappa statistics. The evaluation of the aqueductal patency by T2W 3D-SPACE and T2W 2D-TSE were in agreement with PC-MRI in 100% (99/99; sensitivity, 100% [83/83]; specificity, 100% [16/16]) and 83.8% (83/99; sensitivity, 100% [67/83]; specificity, 100% [16/16]), respectively (p < 0.001). No significant difference in image quality between T2W 2D-TSE and T2W 3D-SPACE (p = 0.056) occurred. The kappa values for inter-observer agreement were 0.714 for T2W 2D-TSE and 0.899 for T2W 3D-SPACE. Three-dimensional-SPACE is superior to 2D-TSE for the evaluation of aqueductal patency in hydrocephalus. T2W 3D-SPACE may hold promise as a highly accurate alternative treatment to PC-MRI for the physiological and morphological evaluation of aqueductal patency.

  19. Spectroscopic analysis and control

    DOEpatents

    Tate; , James D.; Reed, Christopher J.; Domke, Christopher H.; Le, Linh; Seasholtz, Mary Beth; Weber, Andy; Lipp, Charles

    2017-04-18

    Apparatus for spectroscopic analysis which includes a tunable diode laser spectrometer having a digital output signal and a digital computer for receiving the digital output signal from the spectrometer, the digital computer programmed to process the digital output signal using a multivariate regression algorithm. In addition, a spectroscopic method of analysis using such apparatus. Finally, a method for controlling an ethylene cracker hydrogenator.

  20. Development of a THz spectroscopic imaging system.

    PubMed

    Usami, M; Iwamoto, T; Fukasawa, R; Tani, M; Watanabe, M; Sakai, K

    2002-11-07

    We have developed a real-time THz imaging system based on the two-dimensional (2D) electro-optic (EO) sampling technique. Employing the 2D EO-sampling technique, we can obtain THz images using a CCD camera at a video rate of up to 30 frames per second. A spatial resolution of 1.4 mm was achieved. This resolution was reasonably close to the theoretical limit determined by diffraction. We observed not only static objects but also moving ones. To acquire spectroscopic information, time-domain images were collected. By processing these images on a computer, we can obtain spectroscopic images. Spectroscopy for silicon wafers was demonstrated.

  1. Quantum limited heterodyne detection of spin noise

    NASA Astrophysics Data System (ADS)

    Cronenberger, S.; Scalbert, D.

    2016-09-01

    Spin noise spectroscopy is a powerful technique for studying spin relaxation in semiconductors. In this article, we propose an extension of this technique based on optical heterodyne detection of spin noise, which provides several key advantages compared to conventional spin noise spectroscopy: detection of high frequency spin noise not limited by detector bandwidth or sampling rates of digitizers, quantum limited sensitivity even in case of very weak probe power, and possible amplification of the spin noise signal. Heterodyne detection of spin noise is demonstrated on insulating n-doped GaAs. From measurements of spin noise spectra up to 0.4 Tesla, we determined the distribution of g-factors, Δg/g = 0.49%.

  2. Spin-Charge Conversion Phenomena in Germanium

    NASA Astrophysics Data System (ADS)

    Oyarzún, Simón; Rortais, Fabien; Rojas-Sánchez, Juan-Carlos; Bottegoni, Federico; Laczkowski, Piotr; Vergnaud, Céline; Pouget, Stéphanie; Okuno, Hanako; Vila, Laurent; Attané, Jean-Philippe; Beigné, Cyrille; Marty, Alain; Gambarelli, Serge; Ducruet, Clarisse; Widiez, Julie; George, Jean-Marie; Jaffrès, Henri; Jamet, Matthieu

    2017-01-01

    The spin-orbit coupling relating the electron spin and momentum allows for spin generation, detection and manipulation. It thus fulfils the three basic functions of the spin field-effect-transistor made of semiconductors. In this paper, we review our recent results on spin-charge conversion in bulk germanium and at the Ge(111) surface. We used the spin pumping technique to generate pure spin currents to be injected into bulk germanium and at the Fe/Ge(111) interface. The mechanism for spin-charge conversion in bulk germanium is the spin Hall effect and we could experimentally determine the spin Hall angle θSHE, i.e., the spin-charge conversion efficiency, in heavily doped n-type and p-type germanium. We found very small values at room temperature: θSHE ≈ (1-2) × 10-3 in n-Ge and θSHE ≈ (6-7) × 10-4 in p-Ge. Moreover, we pointed out the essential role of spin dependent scattering on ionized impurities in the spin Hall effect mechanism. We concluded that the spin Hall effect in bulk germanium is too weak to produce large spin currents, whereas a large Rashba effect (>100 meV) at Ge(111) surfaces covered with heavy metals could generate spin polarized currents. We could indeed demonstrate a giant spin-to-charge conversion in metallic states at the Fe/Ge(111) interface due to the Rashba coupling. We generated very large charge currents by direct spin pumping into the interface states from 20 K to room temperature. By this, we raise a new paradigm: the possibility to use the spin-orbit coupling for the development of the spin-field-effect-transistor.

  3. Structure of odd-odd 136La at high spin

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Tumpa; Chanda, Somen; Bhattacharyya, Sarmishtha; Basu, Swapan Kumar; Bhowmik, R. K.; Muralithar, S.; Singh, R. P.; Pattabiraman, N. S.; Ghugre, S. S.; Datta Pramanik, U.; Bhattacharya, S.

    2005-04-01

    The high spin states in the N=79 odd-odd 136La nucleus have been investigated by in-beam γ-spectroscopic techniques following the 130Te( 11B, 5 n) 136La reaction at E=52 MeV using an array, consisting of eight Compton-suppressed clover germanium detectors. Thirty nine new γ rays have been assigned to 136La on the basis of γ ray singles and γγ-coincidence data. The level scheme of 136La has been extended above the known 115 ms isomer upto an excitation energy of 4.6 MeV and spin 18 ℏ. Thirty one new levels have been proposed and spin-parity assignments for most of the newly proposed levels have been made on the basis of the deduced asymmetry ratios and polarisation information for the de-exciting transitions. The observed positive parity yrast band has been compared with the theoretical calculation, done within the framework of particle rotor coupling model (PRM) where the two odd quasi-particles are coupled to an axially symmetric core. The level structure has been discussed in the light of the known systematics of the neighbouring N=79 isotonic nuclei.

  4. Spin-asymmetric Josephson plasma oscillations

    NASA Astrophysics Data System (ADS)

    Kreula, J. M.; Valtolina, G.; Törmä, P.

    2017-01-01

    The spin-asymmetric Josephson effect is a proposed quantum-coherent tunneling phenomenon where Cooper-paired fermionic spin-1/2 particles, which are subjected to spin-dependent potentials across a Josephson junction, undergo frequency-synchronized alternating-current Josephson oscillations with spin-dependent amplitudes. Here, in line with present-day techniques in ultracold Fermi gas setups, we consider the regime of small Josephson oscillations and show that the Josephson plasma oscillation amplitude becomes spin dependent in the presence of spin-dependent potentials, while the Josephson plasma frequency is the same for both spin components. Detecting these spin-dependent Josephson plasma oscillations provides a possible means to establish the yet-unobserved spin-asymmetric Josephson effect with ultracold Fermi gases using existing experimental tools.

  5. Controlled spatial separation of spins and coherent dynamics in spin-orbit-coupled nanostructures

    PubMed Central

    Lo, Shun-Tsung; Chen, Chin-Hung; Fan, Ju-Chun; Smith, L. W.; Creeth, G. L.; Chang, Che-Wei; Pepper, M.; Griffiths, J. P.; Farrer, I.; Beere, H. E.; Jones, G. A. C.; Ritchie, D. A.; Chen, Tse-Ming

    2017-01-01

    The spatial separation of electron spins followed by the control of their individual spin dynamics has recently emerged as an essential ingredient in many proposals for spin-based technologies because it would enable both of the two spin species to be simultaneously utilized, distinct from most of the current spintronic studies and technologies wherein only one spin species could be handled at a time. Here we demonstrate that the spatial spin splitting of a coherent beam of electrons can be achieved and controlled using the interplay between an external magnetic field and Rashba spin–orbit interaction in semiconductor nanostructures. The technique of transverse magnetic focusing is used to detect this spin separation. More notably, our ability to engineer the spin–orbit interactions enables us to simultaneously manipulate and probe the coherent spin dynamics of both spin species and hence their correlation, which could open a route towards spintronics and spin-based quantum information processing. PMID:28691707

  6. A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies

    ERIC Educational Resources Information Center

    Ramos, Carlos Henrique I.

    2004-01-01

    This article describes a practical experiment for teaching basic spectroscopic techniques to introduce the topic of protein conformational change to students in the field of molecular biology, biochemistry, or structural biology. The spectroscopic methods employed in the experiment are absorbance, for protein concentration measurements, and…

  7. A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies

    ERIC Educational Resources Information Center

    Ramos, Carlos Henrique I.

    2004-01-01

    This article describes a practical experiment for teaching basic spectroscopic techniques to introduce the topic of protein conformational change to students in the field of molecular biology, biochemistry, or structural biology. The spectroscopic methods employed in the experiment are absorbance, for protein concentration measurements, and…

  8. Coherent Imaging Spectroscopy of a Quantum Many-Body Spin System

    NASA Astrophysics Data System (ADS)

    Smith, Jacob; Senko, Crystal; Richerme, Phil; Lee, Aaron; Campbell, Wes; Monroe, Chris

    2014-05-01

    Trapped-ion quantum simulators are a promising candidate for exploring quantum-many-body physics, such as quantum magnetism, that are difficult to examine in condensed-matter experiments or using classical simulation. We demonstrate a coherent imaging spectroscopic technique to validate a quantum simulation. In this work, we study fully-connected transverse Ising models with a chain of up to 18 171Yb+ ions. Here, We resolve the state of each spin by collecting the spin-dependent fluorescence on a camera in order to map the complete energy spectrum and fully characterize the spin-spin couplings, while also engineering entangled states and measuring the critical gap near a quantum phase transition. We expect this general technique to become an important verification tool for quantum simulators. This work is supported by grants from the U.S. Army Research Office with funding from the DARPA OLE program, IARPA, and the MURI program; and the NSF Physics Frontier Center at JQI.

  9. Paramagnetic Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

    Wu, Stephen M.; Pearson, John E.; Bhattacharya, Anand

    2015-05-01

    We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (<20 K ), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which produces a phenomenologically similar signal.

  10. Paramagnetic spin seebeck effect.

    PubMed

    Wu, Stephen M; Pearson, John E; Bhattacharya, Anand

    2015-05-08

    We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (<20  K), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which produces a phenomenologically similar signal.

  11. Paramagnetic Spin Seebeck Effect

    SciTech Connect

    Wu, Stephen M.; Pearson, John E.; Bhattacharya, Anand

    2015-05-01

    We report the observation of the longitudinal spin Seebeck effect in paramagnetic insulators. By using a microscale on-chip local heater, we generate a large thermal gradient confined to the chip surface without a large increase in the total sample temperature. Using this technique at low temperatures (< 20 K), we resolve the paramagnetic spin Seebeck effect in the insulating paramagnets Gd3Ga5O12 (gadolinium gallium garnet) and DyScO3 (DSO), using either W or Pt as the spin detector layer. By taking advantage of the strong magnetocrystalline anisotropy of DSO, we eliminate contributions from the Nernst effect in W or Pt, which produces a phenomenologically similar signal.

  12. Calibration method for spectroscopic systems

    DOEpatents

    Sandison, David R.

    1998-01-01

    Calibration spots of optically-characterized material placed in the field of view of a spectroscopic system allow calibration of the spectroscopic system. Response from the calibration spots is measured and used to calibrate for varying spectroscopic system operating parameters. The accurate calibration achieved allows quantitative spectroscopic analysis of responses taken at different times, different excitation conditions, and of different targets.

  13. Calibration method for spectroscopic systems

    DOEpatents

    Sandison, D.R.

    1998-11-17

    Calibration spots of optically-characterized material placed in the field of view of a spectroscopic system allow calibration of the spectroscopic system. Response from the calibration spots is measured and used to calibrate for varying spectroscopic system operating parameters. The accurate calibration achieved allows quantitative spectroscopic analysis of responses taken at different times, different excitation conditions, and of different targets. 3 figs.

  14. On the performance of Spin Diffusion NMR Techniques in Oriented Solids: Prospects for Resonance Assignments and Distance Measurements from Separated Local Field Experiments

    PubMed Central

    Traaseth, Nathaniel J.; Gopinath, T.; Veglia, Gianluigi

    2010-01-01

    NMR spin diffusion experiments have the potential to provide both resonance assignment and internuclear distances for protein structure determination in oriented solid-state NMR. In this paper, we compared the efficiencies of three common spin diffusion experiments: proton-driven spin diffusion (PDSD), cross-relaxation driven spin diffusion (CRDSD), and proton-mediated proton transfer (PMPT). As model systems for oriented proteins, we used single crystals of N-acetyl-L-15N-leucine (NAL) and N-acetyl-L-15N-valyl-L-15N-leucine (NAVL) to probe long- and short distances, respectively. We demonstrate that for short 15N/15N distances such as those found in NAVL (3.3 Å), the PDSD mechanism gives the most intense cross-peaks, while for longer distances (> 6.5 Å), the CRDSD and PMPT experiments are more efficient. The PDSD was highly inefficient for transferring magnetization across distances greater than 6.5 Å (NAL crystal sample), due to small 15N/15N dipolar couplings (< 4.5 Hz). Interestingly, the mismatched Hartmann-Hahn condition present in the PMPT experiment gave more intense cross-peaks for lower 1H and 15N spinlock field strengths (32 and 17 kHz, respectively) rather than higher values (55 and 50 kHz), suggesting a more complex magnetization transfer mechanism. Numerical simulations are in good agreement with the experimental findings, suggesting a combined PMPT and CRDSD effect. We conclude that in order to assign SLF spectra and measure short and long-range distances, the combined use of homonuclear correlation spectra, such as the ones surveyed in this work, are necessary. PMID:20936833

  15. On the performance of spin diffusion NMR techniques in oriented solids: prospects for resonance assignments and distance measurements from separated local field experiments.

    PubMed

    Traaseth, Nathaniel J; Gopinath, T; Veglia, Gianluigi

    2010-11-04

    NMR spin diffusion experiments have the potential to provide both resonance assignment and internuclear distances for protein structure determination in oriented solid-state NMR. In this paper, we compared the efficiencies of three spin diffusion experiments: proton-driven spin diffusion (PDSD), cross-relaxation-driven spin diffusion (CRDSD), and proton-mediated proton transfer (PMPT). As model systems for oriented proteins, we used single crystals of N-acetyl-L-(15)N-leucine (NAL) and N-acetyl-L-(15)N-valyl-L-(15)N-leucine (NAVL) to probe long and short distances, respectively. We demonstrate that, for short (15)N/(15)N distances such as those found in NAVL (3.3 Å), the PDSD mechanism gives the most intense cross-peaks, while, for longer distances (>6.5 Å), the CRDSD and PMPT experiments are more efficient. The PDSD was highly inefficient for transferring magnetization across distances greater than 6.5 Å (NAL crystal sample), due to small (15)N/(15)N dipolar couplings (<4.5 Hz). Interestingly, the mismatched Hartmann-Hahn condition present in the PMPT experiment gave more intense cross-peaks for lower (1)H and (15)N RF spinlock amplitudes (32 and 17 kHz, respectively) rather than higher values (55 and 50 kHz), suggesting a more complex magnetization transfer mechanism. Numerical simulations are in good agreement with the experimental findings, suggesting a combined PMPT and CRDSD effect. We conclude that, in order to assign SLF spectra and measure short- and long-range distances, the combined use of homonuclear correlation spectra, such as the ones surveyed in this work, are necessary.

  16. γ-ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination

    DOE PAGES

    Wiedeking, M.; Krticka, M.; Bernstein, L. A.; ...

    2016-02-01

    The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d,p) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p-γ and p-γ-γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p-γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levelsmore » with high spins populated in the (d,p) reaction above the neutron separation energy. As a result, spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method.« less

  17. γ-ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination

    SciTech Connect

    Wiedeking, M.; Krticka, M.; Bernstein, L. A.; Allmond, James M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Daub, B. H.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Larsen, A. C.; Lee, I. -Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.; Volya, A.

    2016-02-01

    The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d,p) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p-γ and p-γ-γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p-γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levels with high spins populated in the (d,p) reaction above the neutron separation energy. As a result, spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method.

  18. Spectroscopic study in Z-pinch discharge

    SciTech Connect

    Garamoon, A.A.; Saudy, A.H.; Shark, W.

    1995-12-31

    The temporal variation of the emitted line intensity has been investigated, and thus an important information about the dynamic ionization stages in the Z-pinch discharge has been studied. Also the electron temperature Te, has been deduced by using a spectroscopic technique.

  19. Overview of spin physics

    SciTech Connect

    Yokosawa, A.

    1992-12-23

    Spin physics activities at medium and high energies became significantly active when polarized targets and polarized beams became accessible for hadron-hadron scattering experiments. My overview of spin physics will be inclined to the study of strong interaction using facilities at Argonne ZGS, Brookhaven AGS (including RHIC), CERN, Fermilab, LAMPF, an SATURNE. In 1960 accelerator physicists had already been convinced that the ZGS could be unique in accelerating a polarized beam; polarized beams were being accelerated through linear accelerators elsewhere at that time. However, there was much concern about going ahead with the construction of a polarized beam because (i) the source intensity was not high enough to accelerate in the accelerator, (ii) the use of the accelerator would be limited to only polarized-beam physics, that is, proton-proton interaction, and (iii) p-p elastic scattering was not the most popular topic in high-energy physics. In fact, within spin physics, [pi]-nucleon physics looked attractive, since the determination of spin and parity of possible [pi]p resonances attracted much attention. To proceed we needed more data beside total cross sections and elastic differential cross sections; measurements of polarization and other parameters were urgently needed. Polarization measurements had traditionally been performed by analyzing the spin of recoil protons. The drawbacks of this technique are: (i) it involves double scattering, resulting in poor accuracy of the data, and (ii) a carbon analyzer can only be used for a limited region of energy.

  20. Infrared Spectroscopic Imaging of Latent Fingerprints and Associated Forensic Evidence

    PubMed Central

    Chen, Tsoching; Schultz, Zachary D.; Levin, Ira W.

    2011-01-01

    Fingerprints reflecting a specific chemical history, such as exposure to explosives, are clearly distinguished from overlapping, and interfering latent fingerprints using infrared spectroscopic imaging techniques and multivariate analysis. PMID:19684917

  1. Electrically-induced Spin Coherence by Ultrafast Electrical Spin Injection.

    NASA Astrophysics Data System (ADS)

    Beschoten, B.; Schreiber, L.; Moritz, J.; Schwark, C.; Guentherodt, G.; Lou, X.; Crowell, P.; Adelmann, C.; Palmstrom, C.

    2008-03-01

    Efficient electrical spin injection from a ferromagnet into a semiconductor has been demonstrated for various material systems by steady-state experiments. We introduce a novel time-resolved technique based on electrical pumping and optical probing. As a pump we apply ultrafast current pulses (˜200ps) to electrically inject spin packets from an iron layer through a reverse biased Schottky barrier into a n-GaAs layer. Spin coherence in the semiconductor is probed by subsequent spin precession in a transverse magnetic field using time-resolved Faraday rotation. We observe spin precession for current pulse widths down to 200 ps. The spin polarization of the spin packets is directly measured by Faraday rotation and is found to increase linearly with the current pulse width for pulses shorter than 3 ns at small magnetic fields. This finding together with independent measurements of the samples' high frequency bandwidth indicate that even shorter than 200 ps pulses might be used for generating coherent spin currents in our devices. Work supported by BMBF, DFG and HGF.

  2. Spectroscopic and theoretical studies of the low-lying states of BaO{sup +}

    SciTech Connect

    Bartlett, Joshua H.; VanGundy, Robert A.; Heaven, Michael C.

    2015-07-28

    The BaO{sup +} cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO{sup +} was identified as X{sup 2}Σ{sup +}, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A{sup 2}Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A{sup 2}Π-X{sup 2}Σ{sup +} transitions were predicted using the MRCI method.

  3. Multislice 1H magnetic resonance spectroscopic imaging: assessment of epilepsy, Alzheimer's disease, and amyotrophic lateral sclerosis

    NASA Astrophysics Data System (ADS)

    Weiner, Michael W.; Maudsley, Andrew A.; Schuff, Norbert; Soher, Brian J.; Vermathen, Peter P.; Fein, George; Laxer, Kenneth D.

    1998-07-01

    Proton magnetic resonance spectroscopic imaging (1H MRSI) with volume pre-selection (i.e. by PRESS) or multislice 1H MRSI was used to investigate changes in brain metabolites in Alzheimer's disease, epilepsy, and amyotrophic lateral sclerosis. Examples of results from several ongoing clinical studies are provided. Multislice 1H MRSI of the human brain, without volume pre-selection offers considerable advantages over previously available techniques. Furthermore, MRI tissue segmentation and completely automated spectra curve fitting greatly facilitate quantitative data analysis. Future efforts will be devoted to obtaining full brain coverage and data acquisition at short spin echo times (TE less than 30 ms) for the detection of metabolites with short T2 relaxation times.

  4. Spin pumping into superconductors: A new probe of spin dynamics in a superconducting thin film

    NASA Astrophysics Data System (ADS)

    Inoue, Masashi; Ichioka, Masanori; Adachi, Hiroto

    2017-07-01

    Spin pumping refers to the microwave-driven spin current injection from a ferromagnet into the adjacent target material. We theoretically investigate the spin pumping into superconductors by fully taking account of impurity spin-orbit scattering that is indispensable to describe diffusive spin transport with finite spin diffusion length. We calculate temperature dependence of the spin pumping signal and show that a pronounced coherence peak appears immediately below the superconducting transition temperature Tc, which survives even in the presence of the spin-orbit scattering. The phenomenon provides us with a new way of studying the dynamic spin susceptibility in a superconducting thin film. This is contrasted with the nuclear magnetic resonance technique used to study a bulk superconductor.

  5. Induction-detection electron spin resonance with spin sensitivity of a few tens of spins

    SciTech Connect

    Artzi, Yaron; Twig, Ygal; Blank, Aharon

    2015-02-23

    Electron spin resonance (ESR) is a spectroscopic method that addresses electrons in paramagnetic materials directly through their spin properties. ESR has many applications, ranging from semiconductor characterization to structural biology and even quantum computing. Although it is very powerful and informative, ESR traditionally suffers from low sensitivity, requiring many millions of spins to get a measureable signal with commercial systems using the Faraday induction-detection principle. In view of this disadvantage, significant efforts were made recently to develop alternative detection schemes based, for example, on force, optical, or electrical detection of spins, all of which can reach single electron spin sensitivity. This sensitivity, however, comes at the price of limited applicability and usefulness with regard to real scientific and technological issues facing modern ESR which are currently dealt with conventional induction-detection ESR on a daily basis. Here, we present the most sensitive experimental induction-detection ESR setup and results ever recorded that can detect the signal from just a few tens of spins. They were achieved thanks to the development of an ultra-miniature micrometer-sized microwave resonator that was operated at ∼34 GHz at cryogenic temperatures in conjunction with a unique cryogenically cooled low noise amplifier. The test sample used was isotopically enriched phosphorus-doped silicon, which is of significant relevance to spin-based quantum computing. The sensitivity was experimentally verified with the aid of a unique high-resolution ESR imaging approach. These results represent a paradigm shift with respect to the capabilities and possible applications of induction-detection-based ESR spectroscopy and imaging.

  6. Induction-detection electron spin resonance with spin sensitivity of a few tens of spins

    NASA Astrophysics Data System (ADS)

    Artzi, Yaron; Twig, Ygal; Blank, Aharon

    2015-02-01

    Electron spin resonance (ESR) is a spectroscopic method that addresses electrons in paramagnetic materials directly through their spin properties. ESR has many applications, ranging from semiconductor characterization to structural biology and even quantum computing. Although it is very powerful and informative, ESR traditionally suffers from low sensitivity, requiring many millions of spins to get a measureable signal with commercial systems using the Faraday induction-detection principle. In view of this disadvantage, significant efforts were made recently to develop alternative detection schemes based, for example, on force, optical, or electrical detection of spins, all of which can reach single electron spin sensitivity. This sensitivity, however, comes at the price of limited applicability and usefulness with regard to real scientific and technological issues facing modern ESR which are currently dealt with conventional induction-detection ESR on a daily basis. Here, we present the most sensitive experimental induction-detection ESR setup and results ever recorded that can detect the signal from just a few tens of spins. They were achieved thanks to the development of an ultra-miniature micrometer-sized microwave resonator that was operated at ˜34 GHz at cryogenic temperatures in conjunction with a unique cryogenically cooled low noise amplifier. The test sample used was isotopically enriched phosphorus-doped silicon, which is of significant relevance to spin-based quantum computing. The sensitivity was experimentally verified with the aid of a unique high-resolution ESR imaging approach. These results represent a paradigm shift with respect to the capabilities and possible applications of induction-detection-based ESR spectroscopy and imaging.

  7. Quantitative spin polarization analysis in photoelectron emission microscopy with an imaging spin filter.

    PubMed

    Tusche, Christian; Ellguth, Martin; Krasyuk, Alexander; Winkelmann, Aimo; Kutnyakhov, Dmytro; Lushchyk, Pavel; Medjanik, Katerina; Schönhense, Gerd; Kirschner, Jürgen

    2013-07-01

    Using a photoelectron emission microscope (PEEM), we demonstrate spin-resolved electron spectroscopic imaging of ultrathin magnetic Co films grown on Cu(100). The spin-filter, based on the spin-dependent reflection of low energy electrons from a W(100) crystal, is attached to an aberration corrected electrostatic energy analyzer coupled to an electrostatic PEEM column. We present a method for the quantitative measurement of the electron spin polarization at 4 × 10³ points of the PEEM image, simultaneously. This approach uses the subsequent acquisition of two images with different scattering energies of the electrons at the W(100) target to directly derive the spin polarization without the need of magnetization reversal of the sample.

  8. Effect of Heat Treatment on the Structural Properties of TiO2 Films Produced by Sol-Gel Spin Coating Technique

    NASA Astrophysics Data System (ADS)

    Nebi, M.; Peker, D.

    2016-10-01

    Due to have superior properties as fotocatalyst and have wide band gap, TiO2 thin films often investigated by researchers and used by technological applications widely. In this study TiO2 films were deposited on glass substrate by Sol-Gel Spin Coating Technic. TiO2 films were deposited at different number of layer and then annealed at 400o C, 500o C, and 600o C in air. Effect of anneal temperature to structural properties were investigated by XRD analysis. It was observed by the light of XRD results that the structural properties of films had changed by anneal temperature.

  9. Effects of Concentration of Precursor and Annealing Temperature on the Optical Properties of Nanostructured Al- doped Zinc Oxide (AZO) Thin films Prepared by Sol-Gel Spin Coating Technique

    NASA Astrophysics Data System (ADS)

    Yusuf, Gbadebo; Awodugba, Ayodeji; Raimi, Adepoju; Efunwole, Hezekiah; Familusi, Timothy

    2013-03-01

    This work investigates the effects of concentration of precursor and annealing temperature on the optical properties of nanostructured Al-doped (AZO) zinc oxide thin films prepared by sol-gel spin coating technique. The sols were prepared using concentration of zinc acetate dehydrate which was varied between 0.1 and 1.4 mole/liter. Aluminium chloride was used as dopant while the annealing temperature of 400° to 650° was chosen. The results show that the concentration between 0.3 to 0.6 moles/liter zinc acetate dehydrate in solution resulted in good thin films with high preferential c-axis orientation and optical transmission reveal a good transmittance within the visible wavelength spectrum region while the concentrations that fall outside this range did not yield films with good c-axis orientation. The films deposited at annealing temperatures 500° and 650° showed surface structures much smaller than 400°. The Spin coating technique creates ZnO films with potential for application as transparent electrodes in optoelectronic devices such as solar cell. The Authors would like to Acknowledge the encouragement and financial support from the Management of Osun state Polytechnic, Iree.

  10. Cavity cooling of an ensemble spin system.

    PubMed

    Wood, Christopher J; Borneman, Troy W; Cory, David G

    2014-02-07

    We describe how sideband cooling techniques may be applied to large spin ensembles in magnetic resonance. Using the Tavis-Cummings model in the presence of a Rabi drive, we solve a Markovian master equation describing the joint spin-cavity dynamics to derive cooling rates as a function of ensemble size. Our calculations indicate that the coupled angular momentum subspaces of a spin ensemble containing roughly 10(11) electron spins may be polarized in a time many orders of magnitude shorter than the typical thermal relaxation time. The described techniques should permit efficient removal of entropy for spin-based quantum information processors and fast polarization of spin samples. The proposed application of a standard technique in quantum optics to magnetic resonance also serves to reinforce the connection between the two fields, which has recently begun to be explored in further detail due to the development of hybrid designs for manufacturing noise-resilient quantum devices.

  11. Spin ejector

    DOEpatents

    Andersen, John A.; Flanigan, John J.; Kindley, Robert J.

    1978-01-01

    The disclosure relates to an apparatus for spin ejecting a body having a flat plate base containing bosses. The apparatus has a base plate and a main ejection shaft extending perpendicularly from the base plate. A compressible cylindrical spring is disposed about the shaft. Bearings are located between the shaft and the spring. A housing containing a helical aperture releasably engages the base plate and surrounds the shaft bearings and the spring. A piston having an aperture follower disposed in the housing aperture is seated on the spring and is guided by the shaft and the aperture. The spring is compressed and when released causes the piston to spin eject the body.

  12. Recovery of spinning satellites

    NASA Technical Reports Server (NTRS)

    Coppey, J. M.; Mahaffey, W. R.

    1977-01-01

    The behavior of a space tug and a spinning satellite in a coupled configuration was simulated and analyzed. A docking concept was developed to investigate the requirements pertaining to the design of a docking interface. Sensing techniques and control requirements for the chase vehicle were studied to assess the feasibility of an automatic docking. The effects of nutation dampers and liquid propellant slosh motion upon the docking transient were investigated.

  13. Spinning yarns for years

    NASA Astrophysics Data System (ADS)

    Kowalewski, Grzegorz

    1997-05-01

    Applications of rather routine high speed photography techniques for research of some textile technologies invented, developed, improved or investigated by the Technical University of Lodz are presented. The following technologies and processes are mentioned: sewing, knitting, spinning, texturing, weaving (including pneumatic methods employed in some technologies). Rotating prism cameras, microsecond flash guns, stereo photography have been mainly applied. Most HSP applications and examples are illustrated by a video presentation.

  14. The kinematic differences between off-spin and leg-spin bowling in cricket.

    PubMed

    Beach, Aaron J; Ferdinands, René E D; Sinclair, Peter J

    2016-09-01

    Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.

  15. Muon spin rotation in solids

    NASA Technical Reports Server (NTRS)

    Stronach, C. E.

    1983-01-01

    The muon spin rotation (MuSR) technique is used to probe the microscopic electron density in materials. High temperature MuSR and magnetization measurements in nickel are in progress to allow an unambiguous determination of the muon impurity interaction and the impurity induced change in local spin density. The first results on uniaxial stress induced frequency shifts in an Fe single crystal are also reported.

  16. Spin polarized tunneling study on spin hall metals and topological insulators (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Luqiao

    2016-10-01

    Spin orbit interactions give rise to interesting physics phenomena in solid state materials such as the spin Hall effect (SHE) and topological insulator surface states. Those effects have been extensively studied using various electrical detection methods. However, to date most experiments focus only on characterizing electrons near the Fermi surface, while spin-orbit interaction is expected to be energy dependent. Here we developed a tunneling spectroscopy technique to measure spin Hall materials and topological insulators under finite bias voltages. By electrically injecting spin polarized electrons into spin Hall metals or topological insulators using tunnel junctions and measuring the induced transverse voltage, we are able to study SHE in typical 5d transition metals and the spin momentum locking in topological insulators. For spin Hall effect metals, the magnitude of the spin Hall angle has been a highly controversial topic in previous studies. Results obtained from various techniques can differ by more than an order of magnitude. Our results from this transport measurement turned out to be consistent with the values obtained from spin Hall torque measurements, which can help to address the long debating issue. Besides the magnitude, the voltage dependent spectra from our experiment also provide useful information in distinguishing between different potential mechanisms. Finally, because of the impedance matching capability of tunnel junctions, the spin polarized tunneling technique can also be used as a powerful tool to measure resistive materials such as the topological insulators. Orders of magnitude improvement in the effective spin Hall angle was demonstrated through our measurement

  17. High-spin states and shell structure of the odd-odd nucleus {sup 90}Nb

    SciTech Connect

    Cui, X.Z.; Zhang, Z.L.; Meng, R.; Yang, C.X.; Zhu, L.H.; Wu, X.G.; Wang, Z.M.; He, C.Y.; Li, G.S.; Wen, S.X.; Ma, R.G.; Liu, Y.; Luo, P.; Zheng, Y.; Ndontchueng, M.M.; Huo, J.D.

    2005-10-01

    The high-spin states of the odd-odd nucleus {sup 90}Nb have been investigated with in-beam {gamma}-spectroscopic techniques via the {sup 76}Ge({sup 19}F,5n){sup 90}Nb reaction at a beam energy of 80 MeV. {gamma}-{gamma} coincidences were measured using a {gamma}-ray detector array. Twenty new {gamma} rays have been assigned to {sup 90}Nb and the level scheme has been extended up to an excitation energy of 8.095 MeV at spin 18({Dirac_h}/2{pi}). The level structure of {sup 90}Nb at high spin states has been well reproduced using semiempirical shell-model calculations in the model space {pi}(1p{sub 1/2},0f{sub 5/2},0g{sub 9/2}){nu}(0g{sub 9/2}). The results show that the excitation of protons plays an important role in generating the high-spin states of {sup 90}Nb.

  18. Kitaev exchange and field-induced quantum spin-liquid states in honeycomb α-RuCl3

    PubMed Central

    Yadav, Ravi; Bogdanov, Nikolay A.; Katukuri, Vamshi M.; Nishimoto, Satoshi; van den Brink, Jeroen; Hozoi, Liviu

    2016-01-01

    Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d5 honeycomb halide α-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferromagnetic, as in 5d5 iridium honeycomb oxides, and indeed defines the largest superexchange energy scale. A ferromagnetic Kitaev coupling is also supported by a detailed analysis of the field-dependent magnetization. Using exact diagonalization and density-matrix renormalization group techniques for extended Kitaev-Heisenberg spin Hamiltonians, we find indications for a transition from zigzag order to a gapped spin liquid when applying magnetic field. Our results offer a unified picture on recent magnetic and spectroscopic measurements on this material and open new perspectives on the prospect of realizing quantum spin liquids in d5 halides and oxides in general. PMID:27901091

  19. Kitaev exchange and field-induced quantum spin-liquid states in honeycomb α-RuCl3.

    PubMed

    Yadav, Ravi; Bogdanov, Nikolay A; Katukuri, Vamshi M; Nishimoto, Satoshi; van den Brink, Jeroen; Hozoi, Liviu

    2016-11-30

    Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d(5) honeycomb halide α-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferromagnetic, as in 5d(5) iridium honeycomb oxides, and indeed defines the largest superexchange energy scale. A ferromagnetic Kitaev coupling is also supported by a detailed analysis of the field-dependent magnetization. Using exact diagonalization and density-matrix renormalization group techniques for extended Kitaev-Heisenberg spin Hamiltonians, we find indications for a transition from zigzag order to a gapped spin liquid when applying magnetic field. Our results offer a unified picture on recent magnetic and spectroscopic measurements on this material and open new perspectives on the prospect of realizing quantum spin liquids in d(5) halides and oxides in general.

  20. Kitaev exchange and field-induced quantum spin-liquid states in honeycomb α-RuCl3

    NASA Astrophysics Data System (ADS)

    Yadav, Ravi; Bogdanov, Nikolay A.; Katukuri, Vamshi M.; Nishimoto, Satoshi; van den Brink, Jeroen; Hozoi, Liviu

    2016-11-01

    Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d5 honeycomb halide α-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferromagnetic, as in 5d5 iridium honeycomb oxides, and indeed defines the largest superexchange energy scale. A ferromagnetic Kitaev coupling is also supported by a detailed analysis of the field-dependent magnetization. Using exact diagonalization and density-matrix renormalization group techniques for extended Kitaev-Heisenberg spin Hamiltonians, we find indications for a transition from zigzag order to a gapped spin liquid when applying magnetic field. Our results offer a unified picture on recent magnetic and spectroscopic measurements on this material and open new perspectives on the prospect of realizing quantum spin liquids in d5 halides and oxides in general.

  1. Spin Electronics

    DTIC Science & Technology

    2003-08-01

    is now well established in scientific and engineering communities that Moore’s Law, having been an excellent predictor of integrated circuit density...for semiconductor electronics, spin-electronic devices have the potential to achieve much higher integration densities. Conventional electronics is...devices would include non-volatility permitting data retention in non-powered conditions, increased integration densities, higher data processing

  2. Spectroscopic Imaging of Strongly Correlated Electronic States

    NASA Astrophysics Data System (ADS)

    Yazdani, Ali; da Silva Neto, Eduardo H.; Aynajian, Pegor

    2016-03-01

    The study of correlated electronic systems from high-Tc cuprates to heavy-fermion systems continues to motivate the development of experimental tools to probe electronic phenomena in new ways and with increasing precision. In the past two decades, spectroscopic imaging with scanning tunneling microscopy has emerged as a powerful experimental technique. The combination of high energy and spatial resolutions provided by this technique reveals unprecedented detail of the electronic properties of strongly correlated metals and superconductors. This review examines specific experiments, theoretical concepts, and measurement methods that have established the application of these techniques to correlated materials. A wide range of applications, such as the study of collective responses to single atomic impurities, the characterization of quasiparticle-like excitations through their interference, and the identification of competing electronic phases using spectroscopic imaging, are discussed.

  3. Y{sub 3}Fe{sub 5}O{sub 12} spin pumping for quantitative understanding of pure spin transport and spin Hall effect in a broad range of materials (invited)

    SciTech Connect

    Du, Chunhui; Wang, Hailong; Hammel, P. Chris; Yang, Fengyuan

    2015-05-07

    Using Y{sub 3}Fe{sub 5}O{sub 12} (YIG) thin films grown by our sputtering technique, we study dynamic spin transport in nonmagnetic, ferromagnetic, and antiferromagnetic (AF) materials by ferromagnetic resonance spin pumping. From both inverse spin Hall effect and damping enhancement, we determine the spin mixing conductance and spin Hall angle in many metals. Surprisingly, we observe robust spin conduction in AF insulators excited by an adjacent YIG at resonance. This demonstrates that YIG spin pumping is a powerful and versatile tool for understanding spin Hall physics, spin-orbit coupling, and magnetization dynamics in a broad range of materials.

  4. Identification of pH-sensitive regions in the mouse prion by the cysteine-scanning spin-labeling ESR technique

    SciTech Connect

    Watanabe, Yasuko; Inanami, Osamu . E-mail: inanami@vetmed.hokudai.ac.jp; Horiuchi, Motohiro; Hiraoka, Wakako; Shimoyama, Yuhei; Inagaki, Fuyuhiko; Kuwabara, Mikinori

    2006-11-24

    We analyzed the pH-induced mobility changes in moPrP{sup C} {alpha}-helix and {beta}-sheets by cysteine-scanning site-directed spin labeling (SDSL) with ESR. Nine amino acid residues of {alpha}-helix1 (H1, codon 143-151), four amino acid residues of {beta}-sheet1 (S1, codon 127-130), and four amino acid residues of {beta}-sheet2 (S2, codon 160-163) were substituted for by cysteine residues. These recombinant mouse PrP{sup C} (moPrP{sup C}) mutants were reacted with a methane thiosulfonate sulfhydryl-specific spin labeling reagent (MTSSL). The 1/{delta}H of the central ({sup 14}N hyperfine) component (M{sub I} = 0) in the ESR spectrum of spin-labeled moPrP{sup C} was measured as a mobility parameter of nitroxide residues (R1). The mobilities of E145R1 and Y149R1 at pH 7.4, which was identified as a tertiary contact site by a previous NMR study of moPrP, were lower than those of D143R1, R147R1, and R150R1 reported on the helix surface. Thus, the mobility in the H1 region in the neutral solution was observed with the periodicity associated with a helical structure. On the other hand, the values in the S2 region, known to be located in the buried side, were lower than those in the S1 region located in the surface side. These results indicated that the mobility parameter of the nitroxide label was well correlated with the 3D structure of moPrP. Furthermore, the present study clearly demonstrated three pH-sensitive sites in moPrP, i.e. (1) the N-terminal tertiary contact site of H1 (2) the C-terminal end of H1, and (3) the S2 region. In particular, among these pH-sensitive sites, the N-terminal tertiary contact region of H1 was found to be the most pH-sensitive one and was easily converted to a flexible structure by a slight decrease of pH in the solution. These data provided molecular evidence to explain the cellular mechanism for conversion from PrP{sup C} to PrP{sup Sc} in acidic organelles such as the endosome.

  5. Spin structure of the proton

    SciTech Connect

    Nathan Isgur

    1995-08-01

    In these lectures the author argues that their response to the spin crisis should not be to abandon the naive quark model baby, but rather to allow it to mature. He begin by recalling what a beautiful baby the quark model is via an overview of its successes in spectroscopy, dynamics, and valence spin structure. He also introduces the conservative hypothesis that dynamical q{anti q} pairs are its key missing ingredient. He then discusses dressing the baby. He first shows that it can be clothed in glue without changing its spectroscopic successes. In the process, several dynamical mysteries associated with quark model spectroscopy are potentially explained. Next, he dresses the baby in q{anti q} pairs, first showing that this can be done without compromising the naive quark model's success with either spectroscopy or the OZI rule. Finally, he shows that despite their near invisibility elsewhere, pairs do play an important role in the proton's spin structure by creating an antipolarized q{anti q} sea. In the context of an explicit calculation he demonstrate that it is plausible that the entire ''spin crisis'' arises from this effect.

  6. Observation of the spin Seebeck effect.

    PubMed

    Uchida, K; Takahashi, S; Harii, K; Ieda, J; Koshibae, W; Ando, K; Maekawa, S; Saitoh, E

    2008-10-09

    The generation of electric voltage by placing a conductor in a temperature gradient is called the Seebeck effect. Its efficiency is represented by the Seebeck coefficient, S, which is defined as the ratio of the generated electric voltage to the temperature difference, and is determined by the scattering rate and the density of the conduction electrons. The effect can be exploited, for example, in thermal electric-power generators and for temperature sensing, by connecting two conductors with different Seebeck coefficients, a device called a thermocouple. Here we report the observation of the thermal generation of driving power, or voltage, for electron spin: the spin Seebeck effect. Using a recently developed spin-detection technique that involves the spin Hall effect, we measure the spin voltage generated from a temperature gradient in a metallic magnet. This thermally induced spin voltage persists even at distances far from the sample ends, and spins can be extracted from every position on the magnet simply by attaching a metal. The spin Seebeck effect observed here is directly applicable to the production of spin-voltage generators, which are crucial for driving spintronic devices. The spin Seebeck effect allows us to pass a pure spin current, a flow of electron spins without electric currents, over a long distance. These innovative capabilities will invigorate spintronics research.

  7. Charge-to-Spin Conversion and Spin Diffusion in Bi/Ag Bilayers Observed by Spin-Polarized Positron Beam

    NASA Astrophysics Data System (ADS)

    Zhang, H. J.; Yamamoto, S.; Gu, B.; Li, H.; Maekawa, M.; Fukaya, Y.; Kawasuso, A.

    2015-04-01

    Charge-to-spin conversion induced by the Rashba-Edelstein effect was directly observed for the first time in samples with no magnetic layer. A spin-polarized positron beam was used to probe the spin polarization of the outermost surface electrons of Bi /Ag /Al2O3 and Ag /Bi /Al2O3 when charge currents were only associated with the Ag layers. An opposite surface spin polarization was found between Bi /Ag /Al2O3 and Ag /Bi /Al2O3 samples with the application of a charge current in the same direction. The surface spin polarizations of both systems decreased exponentially with the outermost layer thickness, suggesting the occurrence of spin diffusion from the Bi/Ag interface to the outermost surfaces. This work provides a new technique to measure spin diffusion length.

  8. Nanoantenna-Enhanced Infrared Spectroscopic Chemical Imaging.

    PubMed

    Kühner, Lucca; Hentschel, Mario; Zschieschang, Ute; Klauk, Hagen; Vogt, Jochen; Huck, Christian; Giessen, Harald; Neubrech, Frank

    2017-05-26

    Spectroscopic infrared chemical imaging is ideally suited for label-free and spatially resolved characterization of molecular species, but often suffers from low infrared absorption cross sections. Here, we overcome this limitation by utilizing confined electromagnetic near-fields of resonantly excited plasmonic nanoantennas, which enhance the molecular absorption by orders of magnitude. In the experiments, we evaporate microstructured chemical patterns of C60 and pentacene with nanometer thickness on top of homogeneous arrays of tailored nanoantennas. Broadband mid-infrared spectra containing plasmonic and vibrational information were acquired with diffraction-limited resolution using a two-dimensional focal plane array detector. Evaluating the enhanced infrared absorption at the respective frequencies, spatially resolved chemical images were obtained. In these chemical images, the microstructured chemical patterns are only visible if nanoantennas are used. This confirms the superior performance of our approach over conventional spectroscopic infrared imaging. In addition to the improved sensitivity, our technique provides chemical selectivity, which would not be available with plasmonic imaging that is based on refractive index sensing. To extend the accessible spectral bandwidth of nanoantenna-enhanced spectroscopic imaging, we employed nanostructures with dual-band resonances, providing broadband plasmonic enhancement and sensitivity. Our results demonstrate the potential of nanoantenna-enhanced spectroscopic infrared chemical imaging for spatially resolved characterization of organic layers with thicknesses of several nanometers. This is of potential interest for medical applications which are currently hampered by state-of-art infrared techniques, e.g., for distinguishing cancerous from healthy tissues.

  9. Spin pumping and spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Saitoh, Eiji

    2012-02-01

    Utilization of a spin current, a flow of electrons' spins in a solid, is the key technology in spintronics that will allow the achievement of efficient magnetic memories and computing devices. In this technology, generation and detection of spin currents are necessary. Here, we review inverse spin-Hall effect and spin-current-generation phenomena recently discovered both in metals and insulators: inverse spin-Hall effect, spin pumping, and spin Seebeck effect. (1)Spin pumping and spin torque in a Mott insulator system We found that spin pumping and spin torque effects appear also at an interface between Pt and an insulator YIG.. This means that we can connect a spin current carried by conduction electrons and a spin-wave spin current flowing in insulators. We demonstrate electric signal transmission by using these effects and interconversion of the spin currents [1]. (2) Spin Seebeck effect We have observed, by using the inverse spin-Hall effect [2], spin voltage generation from a heat current in a NiFe, named the spin-Seebeck effect [3]. Surprisingly, spin-Seebeck effect was found to appear even in insulators [4], a situation completely different from conventional charge Seebeck effect. The result implies an important role of elementary excitation in solids beside charge in the spin Seebeck effect. In the talk, we review the recent progress of the research on this effect. This research is collaboration with K. Ando, K. Uchida, Y. Kajiwara, S. Maekawa, G. E. W. Bauer, S. Takahashi, and J. Ieda. [4pt] [1] Y. Kajiwara and E. Saitoh et al. Nature 464 (2010) 262. [0pt] [2] E. Saitoh et al., Appl. Phys. Lett. 88 (2006) 182509. [0pt] [3] K. Uchida and E. Saitoh et al., Nature 455 (2008)778. [0pt] [4] K. Uchida and E. Saitoh et al.,Nature materials 9 (2010) 894 - 897.

  10. Thermal imaging of spin Peltier effect.

    PubMed

    Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-Ichi

    2016-12-12

    The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The 'spin Peltier effect' modulates the temperature of a magnetic junction in response to spin currents. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by spin currents injected into a magnetic insulator from an adjacent metal. The thermal images reveal characteristic distribution of spin-current-induced heat sources, resulting in the temperature change confined only in the vicinity of the metal/insulator interface. This finding allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is more than one order of magnitude greater than previously believed.

  11. Thermal imaging of spin Peltier effect

    PubMed Central

    Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-ichi

    2016-01-01

    The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The ‘spin Peltier effect' modulates the temperature of a magnetic junction in response to spin currents. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by spin currents injected into a magnetic insulator from an adjacent metal. The thermal images reveal characteristic distribution of spin-current-induced heat sources, resulting in the temperature change confined only in the vicinity of the metal/insulator interface. This finding allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is more than one order of magnitude greater than previously believed. PMID:27941953

  12. Thermal imaging of spin Peltier effect

    NASA Astrophysics Data System (ADS)

    Daimon, Shunsuke; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji; Uchida, Ken-Ichi

    2016-12-01

    The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electr