WorldWideScience

Sample records for crystallography uv spectroscopy

  1. UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

    Science.gov (United States)

    Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

    2016-01-01

    This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

  2. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source

    International Nuclear Information System (INIS)

    Pompidor, Guillaume; Dworkowski, Florian S. N.; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R.

    2013-01-01

    The new version MS2 of the in situ on-axis micro-spectrophotometer at the macromolecular crystallography beamline X10SA of the Swiss Light Source supports the concurrent acquisition of Raman, resonance Raman, fluorescence and UV/Vis absorption spectra along with diffraction data. The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years

  3. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source.

    Science.gov (United States)

    Pompidor, Guillaume; Dworkowski, Florian S N; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R

    2013-09-01

    The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years.

  4. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source

    Science.gov (United States)

    Pompidor, Guillaume; Dworkowski, Florian S. N.; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R.

    2013-01-01

    The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years. PMID:23955041

  5. Development of an online UV-visible microspectrophotometer for a macromolecular crystallography beamline.

    Science.gov (United States)

    Shimizu, Nobutaka; Shimizu, Tetsuya; Baba, Seiki; Hasegawa, Kazuya; Yamamoto, Masaki; Kumasaka, Takashi

    2013-11-01

    Measurement of the UV-visible absorption spectrum is a convenient technique for detecting chemical changes of proteins, and it is therefore useful to combine spectroscopy and diffraction studies. An online microspectrophotometer for the UV-visible region was developed and installed on the macromolecular crystallography beamline, BL38B1, at SPring-8. This spectrophotometer is equipped with a difference dispersive double monochromator, a mercury-xenon lamp as the light source, and a photomultiplier as the detector. The optical path is mostly constructed using mirrors, in order to obtain high brightness in the UV region, and the confocal optics are assembled using a cross-slit diaphragm like an iris to eliminate stray light. This system can measure optical densities up to a maximum of 4.0. To study the effect of radiation damage, preliminary measurements of glucose isomerase and thaumatin crystals were conducted in the UV region. Spectral changes dependent on X-ray dose were observed at around 280 nm, suggesting that structural changes involving Trp or Tyr residues occurred in the protein crystal. In the case of the thaumatin crystal, a broad peak around 400 nm was also generated after X-ray irradiation, suggesting the cleavage of a disulfide bond. Dose-dependent spectral changes were also observed in cryo-solutions alone, and these changes differed with the composition of the cryo-solution. These responses in the UV region are informative regarding the state of the sample; consequently, this device might be useful for X-ray crystallography.

  6. Present needs and future trends in neutron crystallography and spectroscopy

    International Nuclear Information System (INIS)

    Williams, J.M.

    1978-11-01

    Topics covered include: structural investigation by neutron and x-ray diffraction; sources and characteristics of neutron radiation; time-of-flight techniques; overview of neutron crystallography and structural chemistry; hydrogen bonds; transition-metal hydride complexes; actinide and lanthanide complexes; carbon-hydrogen-metal interactions in organometallic chemistry and catalysis; metal clusters and catalysis; materials with unusual solid-state properties; biochemical molecules and biological systems; electron and spin density distributions in crystalline solids; incoherent neutron-scattering spectroscopy; and quasielastic neutron scattering and high resolution spectroscopy

  7. UV spectroscopy. Ch. 16

    International Nuclear Information System (INIS)

    Stevens, Eugene S.

    1991-01-01

    The use of synchrotron radiation (SR) in the ultraviolet (UV) region by biophysics and biophysical chemists continues to increase as access improves and as awareness of its unique combination of properties grows. SR is continuously tunable, intense (even in the UV region), and pulsed. Pulse characteristics are comparable to those of picosecond lasers, but have the advantage of being independent of wavelength. Drawbacks are the continuous, but slow, decay of intensity arising from loss of particles in the ring, and the intrinsic limitation in pulse repetition rate. The particular combination of features that makes SR a superior light source depends upon the application. Spectroscopic techniques based on absorption and some techniques based on emission exploit its intensity and continuous tunability; time resolved techniques make use of its pulse characteristics. This chapter is a status report on two of the major biological applications of UV SR, circular dichroism and time-resolved fluorescence, covering mainly the published literature of the last five years. For the present purpose, the term UV is understood to include the vacuum ultraviolet region to 100 nm. (author). 83 refs.; 4 figs.; 6 tabs

  8. Novel organophosphorus compounds; synthesis, spectroscopy and X-ray crystallography

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Sohrabi, M.; Yousefi, M.; Kovaľ, Tomáš; Dušek, Michal

    2012-01-01

    Roč. 11, č. 2 (2012), s. 125-133 ISSN 1024-1221 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : organophosphorus compounds * NMR * X-ray crystallography * hydrogen bond Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.686, year: 2012

  9. Structural investigation of bistrifluron using x-ray crystallography, NMR spectroscopy, and molecular modeling

    CERN Document Server

    Moon, J K; Rhee, S K; Kim, G B; Yun, H S; Chung, B J; Lee, S S; Lim, Y H

    2002-01-01

    A new insecticide, bistrifluron acts as an inhibitor of insect development and interferes with the cuticle formation of insects. Since it shows low acute oral and dermal toxicities, it can be one of potent insecticides. Based on X-ray crystallography, NMR spectroscopy and molecular modeling, the structural studies of bistrifluron have been carried out.

  10. UV lamp for photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Cardoso, M.J.B.; Landers, R.; Sundaram, V.S.

    1983-01-01

    An UV lamp and a differential pumping system which enables to couple the lamp to an ultra-high vacuum chamber (10 -9 torr) without using windows, are described. The differential between the pressure inside the discharge chamber and the one in de UHV region, which is of 10 8 -10 9 , is achieved with two pumping states separated by pyrex capillaries having an internal diameter of 0.6 mm. In the first stage, a mechanical pump (10 -3 torr) is used; in the second stage, a diffusor pump with a cryogenic trap (N 2 liq - 10 -7 torr) is employed. The lamp produces, when used with high purity He, narrow lines almost clear at 21.2 eV and 40.8 eV, depending on the discharge chamber pressure, thus eliminating the need of a monochromator. As a high voltage source (3 KV), a commercial unit with a good current control was used, ensuring UV beam stability - an essential characteristic for this lamp if it is employed for photoelectron excitation of crystalline samples. (C.L.B.) [pt

  11. a near ambient pressure UV photoelectron spectroscopy

    Indian Academy of Sciences (India)

    Manoj Kumar Ghosalya

    2018-03-02

    Mar 2, 2018 ... UV photoelectron spectroscopy (NAP-UPS) investigations. MANOJ KUMAR ... gations led to various models of Ag-O2 interaction to explain its role in the .... charge lamp (for He I and He II excitations) are available as photon ...

  12. Phosphoramidates: synthesis, spectroscopy, and X-ray crystallography

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Sohrabi, M.; Yousefi, M.; Kovaľ, Tomáš; Dušek, Michal

    2012-01-01

    Roč. 23, č. 5 (2012), s. 478-485 ISSN 1042-7163 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : phosphoramidates * X-ray diffraction * spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.577, year: 2012

  13. X-ray spectroscopy and X-ray crystallography of metalloenzymes at XFELs

    International Nuclear Information System (INIS)

    Yano, Junko

    2016-01-01

    The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting crystallography data and X-ray emission spectra, using an energy dispersive spectrometer at ambient conditions. In addition, we have developed a way to collect metal L-edge data of dilute samples using soft X-rays at XFELs. The advantages and challenges of these methods will be described in this review. (author)

  14. NATURAL CYCLOPENTANOID CYANOHYDRIN GLYCOSIDES .13. STRUCTURE DETERMINATION OF NATURAL EPOXYCYCLOPENTANES BY X-RAY CRYSTALLOGRAPHY AND NMR-SPECTROSCOPY

    DEFF Research Database (Denmark)

    Olafsdottir, E. S.; Sorensen, A. M.; Cornett, Claus

    1991-01-01

    nonannellated cyclopentane derivatives. The new glucosides were shown, by NMR spectroscopy (including NOE measurements), X-ray crystallography, and enzymatic hydrolysis to the corresponding cyanohydrins, to be (1R,2R,3R,4R)- and (1S,2S,3S,4S)-1-(beta-D-glucopyranosyloxy)-2,3-epoxy-4-hydroxycyclopenta ne-1...

  15. UV-VIS absorption spectroscopy: Lambert-Beer reloaded

    Science.gov (United States)

    Mäntele, Werner; Deniz, Erhan

    2017-02-01

    UV-VIS absorption spectroscopy is used in almost every spectroscopy laboratory for routine analysis or research. All spectroscopists rely on the Lambert-Beer Law but many of them are less aware of its limitations. This tutorial discusses typical problems in routine spectroscopy that come along with technical limitations or careless selection of experimental parameters. Simple rules are provided to avoid these problems.

  16. UV and vacuum-UV biological spectroscopy using synchrotron radiation

    International Nuclear Information System (INIS)

    Ito, Amando Siuiti

    1996-01-01

    Full text. Synchrotron radiation has been used as light source in the UV and VUV region for the study of many biological systems. In the time domain, measurements are made that allow the observation of dynamics and kinetics of biomolecules like proteins and peptides, using the fluorescent properties of either intrinsic or extrinsic probes. Optical activity of groups inside biomolecules allows the use of circular dichroism techniques to generate structural information and to follow processes like protein folding. Confocal scanning of synchrotron light generates microscopy resolution below 100 nm, allowing the creation of high quality three dimensional images of biological samples, and the collection of fluorescence originated from microvolumes inside the samples. We propose a station at LNLS for these three techniques: time-resolved fluorescence, circular dischroism and confocal microscopy, using UV and VUV light. (author)

  17. UV laser long-path absorption spectroscopy

    Science.gov (United States)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

  18. UV Spectroscopy of Metallic Asteroid (16) Psyche

    Science.gov (United States)

    Cunningham, N. J.; Becker, T. M.; Retherford, K. D.; Roth, L.; Feaga, L. M.; Wahlund, J.-E.; Elkins-Tanton, L. T.

    2017-09-01

    Asteroid (16) Psyche is the largest M-type asteroid, and the planned destination of the NASA Discovery mission Psyche and the proposed ESA M5 mission Heavy Metal. Psyche is considered to be the exposed core of a differentiated asteroid, whose mantle has been stripped by collisions; but other histories have been proposed. We observed Psyche with the Space Telescope Imaging Spectrograph (STIS) and Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope, to obtain a full ultraviolet (UV) spectrum of both of Psyche's hemispheres. We seek to test three possible scenarios for Psyche's origin: Is Psyche the exposed core of a differentiated asteroid? Is it an asteroid with high olivine content that has been space-weathered? Or did Psyche accrete as-is in a highly-reducing environment early in the history of the solar system? We will present the UV spectra and their implications for Psyche's history.

  19. Synthesis, spectroscopy, X-ray crystallography, and DFT computations of nanosized phosphazenes

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Moghadam, E.J.; Maghsoudi, N.; Mousavi, H.S.M.; Dušek, Michal; Eigner, Václav

    2015-01-01

    Roč. 641, č. 5 (2015), s. 967-978 ISSN 0044-2313 Grant - others:AV ČR(CZ) Praemium Academiae Institutional support: RVO:68378271 Keywords : phosphazene * ultrasonic * nanoparticle * x-ray crystallography * DFT calculation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.261, year: 2015

  20. UV spectroscopy applied to stratospheric chemistry, methods and results

    Energy Technology Data Exchange (ETDEWEB)

    Karlsen, K.

    1996-03-01

    The publication from the Norwegian Institute for Air Research (NILU) deals with an investigation done on stratospheric chemistry by UV spectroscopy. The scientific goals are briefly discussed, and it gives the results from the measuring and analysing techniques used in the investigation. 6 refs., 11 figs.

  1. Synthesis, X-ray crystallography, spectroscopy, electrochemistry, thermal and kinetic study of uranyl Schiff base complexes

    Czech Academy of Sciences Publication Activity Database

    Asadi, Z.; Golzard, F.; Eigner, Václav; Dušek, Michal

    2013-01-01

    Roč. 66, č. 20 (2013), s. 3629-3646 ISSN 0095-8972 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : X-ray crystallography * uranyl Schiff base complex * kinetics of thermal decomposition * cyclic voltammetry * kinetics and mechanism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.224, year: 2013

  2. UV-VIS and photoluminescence spectroscopy for nanomaterials characterization

    CERN Document Server

    2013-01-01

    Second volume of a 40-volume series on nanoscience and nanotechnology, edited by the renowned scientist Challa S.S.R. Kumar. This handbook gives a comprehensive overview about UV-visible and photoluminescence spectroscopy for the characterization of nanomaterials. Modern applications and state-of-the-art techniques are covered and make this volume essential reading for research scientists in academia and industry in the related fields.

  3. Synthesis and structure elucidation of a series of pyranochromene chalcones and flavanones using 1D and 2D NMR spectroscopy and X-ray crystallography.

    Science.gov (United States)

    Pawar, Sunayna S; Koorbanally, Neil A

    2014-06-01

    A series of novel pyranochromene chalcones and corresponding flavanones were synthesized. This is the first report on the confirmation of the absolute configuration of chromene-based flavanones using X-ray crystallography. These compounds were characterized by 2D NMR spectroscopy, and their assignments are reported herein. The 3D structure of the chalcone 3b and flavanone 4g was determined by X-ray crystallography, and the structure of the flavanone was confirmed to be in the S configuration at C-2. Copyright © 2014 John Wiley & Sons, Ltd.

  4. Cost Effective Process Monitoring using UV-VIS-NIR Spectroscopy

    International Nuclear Information System (INIS)

    Cipiti, B.; McDaniel, M.; Bryan, S.; Pratt, S.

    2015-01-01

    UV-VIS-NIR Spectroscopy is a simple and inexpensive measurement technology which has been proposed for process monitoring applications at reprocessing plants. The purpose of this work was to examine if spectroscopy could replace more costly analytical measurements to reduce the safeguards burden to the operator or inspector. Recognizing that the higher measurement uncertainty of spectroscopy makes it unsuited for the accountability tanks, the approach instead was to focus on replacing mass spectrometry for random samples that are taken in a plant. The Interim Inventory Verification and Short Inventory Verification (IIV/SIV) at the Rokkasho Reprocessing Plant utilize random sampling of internal process vessels and laboratory measurement using Isotope Dilution Mass Spectrometry (IDMS) to account for plutonium on a timely basis. These measurements are time-consuming, and the low uncertainty may not always be required. For this work, modelling was used to examine if spectroscopy could be used without adversely affecting the safeguards of the plant. The Separation and Safeguards Performance Model (SSPM), developed at Sandia National Laboratories, was utilized to examine the replacement of IDMS measurements with spectroscopy. Modeling results showed that complete replacement of IDMS with spectroscopy lowered the detection probability for diversion by an unacceptable amount. However, partial replacement (only for samples from vessels with low plutonium content) did not adversely affect the detection probability. This partial replacement covers roughly half of the twenty or so sampling points used for the IIV/SIVA cost-benefit analysis was completed to determine the cost savings that this approach can provide based on lower equipment costs, maintenance, and reduction of analysts' time. This work envisions working with the existing sampling system and performing the spectroscopic measurements in the analytical laboratory, but future work could examine incorporating

  5. Kissing G domains of MnmE monitored by X-ray crystallography and pulse electron paramagnetic resonance spectroscopy.

    Directory of Open Access Journals (Sweden)

    Simon Meyer

    2009-10-01

    Full Text Available MnmE, which is involved in the modification of the wobble position of certain tRNAs, belongs to the expanding class of G proteins activated by nucleotide-dependent dimerization (GADs. Previous models suggested the protein to be a multidomain protein whose G domains contact each other in a nucleotide dependent manner. Here we employ a combined approach of X-ray crystallography and pulse electron paramagnetic resonance (EPR spectroscopy to show that large domain movements are coupled to the G protein cycle of MnmE. The X-ray structures show MnmE to be a constitutive homodimer where the highly mobile G domains face each other in various orientations but are not in close contact as suggested by the GDP-AlF(x structure of the isolated domains. Distance measurements by pulse double electron-electron resonance (DEER spectroscopy show that the G domains adopt an open conformation in the nucleotide free/GDP-bound and an open/closed two-state equilibrium in the GTP-bound state, with maximal distance variations of 18 A. With GDP and AlF(x, which mimic the transition state of the phosphoryl transfer reaction, only the closed conformation is observed. Dimerization of the active sites with GDP-AlF(x requires the presence of specific monovalent cations, thus reflecting the requirements for the GTPase reaction of MnmE. Our results directly demonstrate the nature of the conformational changes MnmE was previously suggested to undergo during its GTPase cycle. They show the nucleotide-dependent dynamic movements of the G domains around two swivel positions relative to the rest of the protein, and they are of crucial importance for understanding the mechanistic principles of this GAD.

  6. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    Directory of Open Access Journals (Sweden)

    S. Delbaere

    2006-01-01

    is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data (λmax⁡ of colored form, colorability, and rate constant of bleaching obtained by UV-visible spectroscopy are reported.

  7. Experimental and theoretical evidence of a supercritical-like transition in an organic semiconductor presenting colossal uniaxial negative thermal expansion† †Electronic supplementary information (ESI) available: Diffraction and crystallography, Cambridge Structural Database survey, DFT computational details, UV spectroscopy, differential scanning calorimetry, and optical microscopy. CCDC 1810678–1810688. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8sc00159f

    Science.gov (United States)

    Roche, Gilles H.; Wantz, Guillaume; Moreau, Joël J. E.; Dautel, Olivier J.; Filhol, Jean-Sébastien

    2018-01-01

    Thermal expansion coefficients of most materials are usually small, typically up to 50 parts per million per kelvin, and positive, i.e. materials expand when heated. Some materials show an atypical shrinking behavior in one or more crystallographic directions when heated. Here we show that a high mobility thiophene-based organic semiconductor, BHH-BTBT, has an exceptionally large negative expansion between 95 and 295 K (–216 BTBT, a much studied organic semiconductor with a closely related molecular formula and 3D crystallographic structure. Complete theoretical characterization of BHH-BTBT using ab initio molecular dynamics shows that below ∼200 K two different α and β domains exist of which one is dominant but which dynamically exchange around and above 210 K. A supercritical-like transition from an α dominated phase to a β dominated phase is observed using DSC measurements, UV-VIS spectroscopy, and X-ray diffraction. The origin of the extreme negative and positive thermal expansion is related to steric hindrance between adjacent tilted thiophene units and strongly enhanced by attractive S···S and S···C interactions within the highly anharmonic mixed-domain phase. This material could trigger the tailoring of optoelectronic devices highly sensitive to strain and temperature. PMID:29780527

  8. The application of UV LEDs for differential optical absorption spectroscopy

    Science.gov (United States)

    Geiko, Pavel P.; Smirnov, Sergey S.; Samokhvalov, Ignatii V.

    2018-04-01

    Modern UV LEDs represent a potentially very advantageous alternative to thermal light sources, in particular xenon arc lamps, which are the most common light sources in trace gas-analyzers. So, the light-emitting diodes are very attractive for use of as light sources for Long Path Differential Optical Absorption Spectroscopy (DOAS) measurements of trace gases in the open atmosphere. Recent developments in fibre-coupling telescope technology and the availability of ultraviolet light emitting diodes have now allowed us to construct a portable, long path DOAS instrument for use at remote locations and specifically for measuring degassing from active volcanic systems. First of all, we are talking about the measurement of sulphur dioxide, carbon disulphide and, oxides of chlorine and bromine. The parallel measurements of sulfur dioxide using a certified gas analyzer, were conducted and showed good correlation.

  9. Stand-off detection of chemicals by UV Raman spectroscopy

    International Nuclear Information System (INIS)

    Wu, Ming; Ray, Mark; Hang Fung, K.; Ruckman, Mark W.; Harder, David; Sedlacek, Arthur J. III

    2000-01-01

    Experimental results are reported on a mobile, stand-alone, solar-blind ultraviolet (UV) Raman lidar system for the stand-off detection and identification of liquid and solid targets at ranges of hundreds of meters. The lidar is a coaxial system capable of performing range-resolved measurements of gases and aerosols, as well as solids and liquids. The transmitter is a flash lamp pumped 30 Hz Nd:YAG laser with quadrupled output at 266 nm. The receiver subsystem is comprised of a 40 cm Cassegrain telescope, a holographic UV edge filter for suppressing the elastic channel, a 0.46 m Czerny-Turner spectrometer, and a time gated intensified charge-coupled device (CCD) detector. The rejection of elastic light scattering by the edge filter is better than one part in 10 5 , while the transmittance 500 cm-1 to the red of the laser line is greater than 50%. Raman data are shown for selected solids, neat liquids, and mixtures down to the level of 1% volume ratio. On the basis of the strength of the Raman returns, a stand-off detection limit of ∼500 g/m2 for liquid spills of common solvents at the range of one half of a kilometer is possible. (c) 2000 Society for Applied Spectroscopy

  10. Prophyrin identification by 3rd derivative UV/VIS spectroscopy

    International Nuclear Information System (INIS)

    Freeman, D.H.; Saint Martin, D.C.; Boreham, C.J.

    1992-01-01

    This patent describes the Soret band wavelength of nickel and vanadyl porphyrins λ Soret, which identifies etic DPEP/di-DPEP, propano and butano structure types. The approach is based upon routine diode array uv/vis spectra taken to their 3rd derivative. an interpolated zero crossing gives λ max within 0.1 nm. Accordingly, reference spectral properties of 27 well characterized metalloporphyrins were determined. When λSoret, λα and λβ and molecular mass data were combined, each of the DPEP and di-DPEP nickel complexes were distinct. In addition, λSoret was able to classify nickel etioporphyrins according to the number of beta hydrogens. To illustrate the many possible applications, two substances were isolated by HPLC from a Messel Shale extract based on known HPLC C18 retentions. Comparison of wavelength and mass between isolated and reference counterparts showed precise agreement. Thus uv/vic spectroscopy helps to classify porphyrin structure, and to facilitate identification by matching to reference data

  11. UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 2: selected applications.

    Science.gov (United States)

    Antosiewicz, Jan M; Shugar, David

    2016-06-01

    In Part 2 we discuss application of several different types of UV-Vis spectroscopy, such as normal, difference, and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, of the side-chain of tyrosine residues in different molecular environments. We review the ways these spectroscopies can be used to probe complex protein structures.

  12. Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy.

    Science.gov (United States)

    Shkolyar, Svetlana; Eshelman, Evan J; Farmer, Jack D; Hamilton, David; Daly, Michael G; Youngbull, Cody

    2018-04-01

    The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest priority targeted samples include aqueously formed sedimentary lithologies. On Earth, such lithologies can contain fossil biosignatures as aromatic carbon (kerogen). In this study, we analyzed nonextracted kerogen in a diverse suite of natural, complex samples using colocated UV excitation (266 nm) time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopies. We interrogated kerogen and its host matrix in samples to (1) explore the capabilities of UV-TG Raman and fluorescence spectroscopies for detecting kerogen in high-priority targets in the search for possible biosignatures on Mars; (2) assess the effectiveness of time gating and UV laser wavelength in reducing fluorescence in Raman spectra; and (3) identify sample-specific issues that could challenge rover-based identifications of kerogen using UV-TG Raman spectroscopy. We found that ungated UV Raman spectroscopy is suited to identify diagnostic kerogen Raman bands without interfering fluorescence and that UV fluorescence spectroscopy is suited to identify kerogen. These results highlight the value of combining colocated Raman and fluorescence spectroscopies, similar to those obtainable by SHERLOC on Mars 2020, to strengthen the confidence of kerogen detection as a potential biosignature in complex natural samples. Key Words: Raman spectroscopy-Laser-induced fluorescence spectroscopy-Mars Sample Return-Mars 2020 mission-Kerogen-Biosignatures. Astrobiology 18, 431-453.

  13. Synthesis, spectroscopy, X-ray crystallography, DFT calculations, DNA binding and molecular docking of a propargyl arms containing Schiff base.

    Science.gov (United States)

    Balakrishnan, C; Subha, L; Neelakantan, M A; Mariappan, S S

    2015-11-05

    A propargyl arms containing Schiff base (L) was synthesized by the condensation of 1-[2-hydroxy-4-(prop-2-yn-1-yloxy)phenyl]ethanone with trans-1,2-diaminocyclohexane. The structure of L was characterized by IR, (1)H NMR, (13)C NMR and UV-Vis spectroscopy and by single crystal X-ray diffraction analysis. The UV-Visible spectral behavior of L in different solvents exhibits positive solvatochromism. Density functional calculation of the L in gas phase was performed by using DFT (B3LYP) method with 6-31G basis set. The computed vibrational frequencies and NMR signals of L were compared with the experimental data. Tautomeric stability study inferred that the enolimine is more stable than the ketoamine form. The charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Electronic absorption and emission spectral studies were used to study the binding of L with CT-DNA. The molecular docking was done to identify the interaction of L with A-DNA and B-DNA. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Multigrain crystallography

    DEFF Research Database (Denmark)

    Sørensen, Henning Osholm; Schmidt, Søren; Wright, Jonathan P.

    2012-01-01

    We summarize exploratory work on multigrain crystallography. The experimental arrangement comprises a monochromatic beam, a fully illuminated sample with up to several hundred grains in transmission geometry on a rotary table and a 2D detector. Novel algorithms are presented for indexing, integra......We summarize exploratory work on multigrain crystallography. The experimental arrangement comprises a monochromatic beam, a fully illuminated sample with up to several hundred grains in transmission geometry on a rotary table and a 2D detector. Novel algorithms are presented for indexing...... of the methodology in terms of number of grains, size of unit cell and direct space resolution. First experimental results in the fields of chemistry, structural biology and time-resolved studies in photochemistry are presented. As an outlook, the concept of TotalCrystallography is introduced, defined...

  15. Solid state structural investigations of the bis(chalcone) compound with single crystal X-ray crystallography, DFT, gamma-ray spectroscopy and chemical spectroscopy methods

    Science.gov (United States)

    Yakalı, Gül; Biçer, Abdullah; Eke, Canel; Cin, Günseli Turgut

    2018-04-01

    A bis(chalcone), (2E,6E)-2,6-bis((E)-3phenylallidene)cyclohexanone, was characterized by 1H NMR, 13C NMR, FTIR, UV-Vis spectroscopy, gamma-ray spectroscopy and single crystal X- ray structural analysis. The optimized molecular structure of the compound is calculated using DFT/B3LYP with 6-31G (d,p) level. The calculated geometrical parameters are in good agreement with the experimental data obtained from our reported X-ray structure. The powder and single crystal compounds were gama-irradiated using clinical electron linear accelerator and 60Co gamma-ray source, respectively. Spectral studies (1H NMR, 13C NMR, FTIR and UV-Vis) of powder chalcone compound were also investigated before and after irradiation. Depending on the irradiation notable changes were observed in spectral features powder sample. Single crystal X-ray diffraction investigation shows that both unirradiated and irradiated single crystal samples crystallizes in a orthorhombic crystal system in the centrosymmetric space group Pbcn and exhibits an C-H..O intramolecular and intermolecular hydrogen bonds. The crystal packing is stabilised by strong intermolecular bifurcate C-H..O hydrogen bonds and π…π stacking interactions. The asymmetric unit of the title compound contains one-half of a molecule. The other half of the molecule is generated with (1-x,y,-3/2-z) symmetry operator. The molecule is almost planar due to having π conjugated system of chalcones. However, irradiated single crystal compound showed significant changes lattice parameters, crystal volume and density. According to results of gamma-ray spectroscopy, radioactive elements of powder compound which are 123Sb(n,g),124Sb,57Fe(g,p),56Mn, 55Mn(g,n), and 54Mn were determined using photoactivation analysis. However, the most intensive gamma-ray energy signals are 124Sb.

  16. In situ UV-Vis spectroscopy in gas-liquid-solid systems

    NARCIS (Netherlands)

    Stemmet, C.P.; Schouten, J.C.; Nijhuis, T.A.

    2010-01-01

    This paper presents the use of ultraviolet-visible spectroscopy (UV-Vis) spectroscopy in a slurry of particles, a packed bubble column, and a trickle bed to assess the changes in the state of an active component on the surface of the solid support. As a model system, insoluble pH indicators

  17. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    OpenAIRE

    S. Delbaere; J. Berthet; M. A. Salvador; G. Vermeersch; M. M. Oliveira

    2006-01-01

    The synthesis of photochromic 3,3-di(4′-fluorophenyl)-3H-benzopyrans fused to an indole moiety is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data (λmax⁡ of colored form, colorability, and rate constant of bleaching) obtained by UV-visible spectroscopy are reported.

  18. Conformation of L-Tyrosine Studied by Fluorescence-Detected UV-UV and IR-UV Double-Resonance Spectroscopy

    OpenAIRE

    Inokuchi, Yoshiya; Kobayashi, Yusuke; Ito, Takafumi; Ebata, Takayuki

    2007-01-01

    The laser-induced fluorescence spectrum of jet-cooled L-tyrosine exhibits more than 20 vibronic bands in the 35450-35750 cm-1 region. We attribute these bands to eight conformers by using results of UV-UV hole-burning spectroscopy. These isomers are classified into four groups; each group consists of two rotational isomers that have a similar side-chain conformation but different orientations of the phenolic OH. The splitting of band origins of rotational isomers is 31, 21, 5, and 0 cm-1 for ...

  19. UV action spectroscopy of protonated PAH derivatives. Methyl substituted quinolines

    DEFF Research Database (Denmark)

    Klærke, Benedikte; Holm, Anne; Andersen, Lars Henrik

    2011-01-01

    using the electrostatic storage ring ELISA, an electrospray ion source and 3 ns UV laser pulses. Results. It is shown that the absorption profile is both redshifted and broadened when moving the methyl group from the heterocycle containing nitrogen to the homoatomic ring. The absorption profiles......Aims. We investigate the production of molecular photofragments upon UV excitation of PAH derivatives, relevant for the interstellar medium. Methods. The action absorption spectra of protonated gas-phase methyl-substituted quinolines (CH3−C9H7NH+) have been recorded in the 215–338 nm spectral range...

  20. Quantitative estimation of diacetylmorphine by preparative TLC and UV spectroscopy

    International Nuclear Information System (INIS)

    Khan, L.; Siddiqui, M.T.; Ahmad, N.; Shafi, N.

    2001-01-01

    A simple and efficient method for the quantitative estimation of di acetylmorphine in narcotic products has been described. Comparative TLC of narcotic specimens with standards showed presence of morphine, monoacetylmorphine, diacetylmorphine papaverine and noscapine, Resolution of the mixtures was achieved by preparative TLC. Bands corresponding to diacetylmorphine scraped, eluted UV absorption of extracts measured and contents quantified. (author)

  1. Applications of derivative UV/VIS spectroscopy in water analysis

    International Nuclear Information System (INIS)

    Hellmann, H.

    1994-01-01

    Derivative UV/VIS spectra offer new possibilities in determination and identification of trace substances in waters, suspended matter, and in sediments. Aromatics and their derivatives, such as alkyl-benzene-sulfonates, esters of phthalic acid, alkyl-phenol-oxethylates etc., but also non-aromatic substances with a π-bond can be identified. Compounds showing no absorption in the UV/VIS range can be detected by adding a suitable corectant, e.g. cationic detergents by means of disulfin-blue of BiJ 4 - . Normally, a clean-up is necessary. The recommended procedure is two- or multi-stage chromatography on adsorbing layers of silica gel or aluminium oxide. Thus, numerous substances can be identified and quantified at levels as low as 5 microgram. In some cases, it will be useful to supplement the method by fluorescent spectra of higher orders. (orig.) [de

  2. Enzyme Characterization in Microreactors by UV-Vis Spectroscopy

    DEFF Research Database (Denmark)

    Ringborg, Rolf Hoffmeyer; Krühne, Ulrich; Woodley, John

    for selection can at this point be improved by characterization of the enzyme performance where also inhibition and toxicity effects are taken into account. Enzyme characterization is here defined as the effect on initial rate of reaction with respect to pH, enzyme, substrate, co-substrate, product and co......-product concentration [2]. From this investigation, it will be possible to determine whether the enzyme meets the criteria for process requirements or not. The development of the process will determine the requirements and this can also reach a state of maturity that resolves obstacles, lowers criteria and paves......, as the enzyme resource is scarce at this point of development. In the case where the reaction operates with UV active components, UV can be used to detect compounds with high sensitivity supplemented by multivariate data analysis. The spectra are here decorrelated and regressed to yield concentrations...

  3. Degradation study of different brands of paracetamol by UV spectroscopy

    Directory of Open Access Journals (Sweden)

    Safila Naveed

    2016-05-01

    Full Text Available Objective: To investgate the forced degradation study for the determination of degradation of the drug substance. Methods: Paracetamol was exposed to different conditions according to International Conference on Harmonization guideline. The amount of degradation product can be calculated with the help of UV spectrophotometer. The official test limits according to British Pharmacopoeia/United States Pharmacopoeia should not less than and should not more than lapelled amount. Forced degradation of drug substance was exposed to acidic and basic medium of panadol. Forced degradation of drug substance of panadol, disprol and calpol were also observed negligible difference in availability on exposure to UV and heat. This method can be used successfully for studying the stress degradation factors. Because this method is less time consuming and simple and cost effective also. Results: The brands i.e. calpol, panadol and disprol, when they come in contact with different degradation parameters (before, acid, base, heat and UV treatments according to statistical analysis, the result showed significant values (P < 0.05 which indicated that there was no degradation in any of the brand. Conclusions: The result indicated there is no degradation found in these brands.

  4. Detection of Explosives on Surfaces Using UV Raman Spectroscopy: Effect of Substrate Color

    Science.gov (United States)

    2017-10-01

    257.23-nm excitation (25 mW at the laser) using 2.5-s integration time and 100 accumulations. Each spectrum is offset by 400 counts from the one...tens of meters have been reported. The testing of UV Raman spectroscopy systems for standoff UV Raman spectroscopy has been generally limited to bare...SP2500A 500-mm focal length monochromator and a PIXIS 400 × 3048 pixel charge-coupled device (CCD) camera (Princeton Instruments, Trenton, NJ). An

  5. The Cosmic Evolution Through UV Spectroscopy (CETUS) Probe Mission Concept

    Science.gov (United States)

    Danchi, William; Heap, Sara; Woodruff, Robert; Hull, Anthony; Kendrick, Stephen E.; Purves, Lloyd; McCandliss, Stephan; Kelly Dodson, Greg Mehle, James Burge, Martin Valente, Michael Rhee, Walter Smith, Michael Choi, Eric Stoneking

    2018-01-01

    CETUS is a mission concept for an all-UV telescope with 3 scientific instruments: a wide-field camera, a wide-field multi-object spectrograph, and a point-source high-resolution and medium resolution spectrograph. It is primarily intended to work with other survey telescopes in the 2020’s (e.g. E-ROSITA (X-ray), LSST, Subaru, WFIRST (optical-near-IR), SKA (radio) to solve major, outstanding problems in astrophysics. In this poster presentation, we give an overview of CETUS key science goals and a progress report on the CETUS mission and instrument design.

  6. High resolution UV spectroscopy and laser-focused nanofabrication

    NARCIS (Netherlands)

    Myszkiewicz, G.

    2005-01-01

    This thesis combines two at first glance different techniques: High Resolution Laser Induced Fluorescence Spectroscopy (LIF) of small aromatic molecules and Laser Focusing of atoms for Nanofabrication. The thesis starts with the introduction to the high resolution LIF technique of small aromatic

  7. Metalloprotein Crystallography: More than a Structure.

    Science.gov (United States)

    Bowman, Sarah E J; Bridwell-Rabb, Jennifer; Drennan, Catherine L

    2016-04-19

    advanced detectors, and the incorporation of spectroscopic equipment at a number of synchrotron beamlines, have yielded exciting developments in metalloprotein structure determination. Here we will present results on the advantageous uses of metals in metalloprotein crystallography, including using metallocofactors to obtain phasing information, using K-edge X-ray absorption spectroscopy to identify metals coordinated in metalloprotein crystals, and using UV-vis spectroscopy on crystals to probe the enzymatic activity of the crystallized protein.

  8. UV photodissociation spectroscopy of oxidized undecylenic acid films.

    Science.gov (United States)

    Gomez, Anthony L; Park, Jiho; Walser, Maggie L; Lin, Ao; Nizkorodov, Sergey A

    2006-03-16

    Oxidation of thin multilayered films of undecylenic (10-undecenoic) acid by gaseous ozone was investigated using a combination of spectroscopic and mass spectrometric techniques. The UV absorption spectrum of the oxidized undecylenic acid film is significantly red-shifted compared to that of the initial film. Photolysis of the oxidized film in the tropospheric actinic region (lambda > 295 nm) readily produces formaldehyde and formic acid as gas-phase products. Photodissociation action spectra of the oxidized film suggest that organic peroxides are responsible for the observed photochemical activity. The presence of peroxides is confirmed by mass-spectrometric analysis of the oxidized sample and an iodometric test. Significant polymerization resulting from secondary reactions of Criegee radicals during ozonolysis of the film is observed. The data strongly imply the importance of photochemistry in aging of atmospheric organic aerosol particles.

  9. In-situ UV-Visible and Raman spectroscopy for gas-liquid-solid systems

    NARCIS (Netherlands)

    Stemmet, C.P.; Schouten, J.C.; Nijhuis, T.A.

    2009-01-01

    This paper presents the use of UV-vis and Raman spectroscopy to measure the state of a solid in a multiphase reactor. A slurry of particles and a packed bubble column were used. As this study is a proof of principle a model for an active catalyst system, insoluble pH indicators deposited on the

  10. Determination of rate constants in second-order kinetics using UV-visible spectroscopy

    NARCIS (Netherlands)

    Bijlsma, S.; Boelens, H. F. M.; Smilde, A. R.

    2001-01-01

    A general method for estimating reaction rate constants of chemical reactions using ultraviolet-visible (UV-vis) spectroscopy is presented. The only requirement is that some of the chemical components involved be spectroscopically active. The method uses the combination of spectroscopic measurements

  11. Instrumentation: Photodiode Array Detectors in UV-VIS Spectroscopy. Part II.

    Science.gov (United States)

    Jones, Dianna G.

    1985-01-01

    A previous part (Analytical Chemistry; v57 n9 p1057A) discussed the theoretical aspects of diode ultraviolet-visual (UV-VIS) spectroscopy. This part describes the applications of diode arrays in analytical chemistry, also considering spectroelectrochemistry, high performance liquid chromatography (HPLC), HPLC data processing, stopped flow, and…

  12. Combined In Situ Illumination-NMR-UV/Vis Spectroscopy: A New Mechanistic Tool in Photochemistry.

    Science.gov (United States)

    Seegerer, Andreas; Nitschke, Philipp; Gschwind, Ruth M

    2018-06-18

    Synthetic applications in photochemistry are booming. Despite great progress in the development of new reactions, mechanistic investigations are still challenging. Therefore, we present a fully automated in situ combination of NMR spectroscopy, UV/Vis spectroscopy, and illumination to allow simultaneous and time-resolved detection of paramagnetic and diamagnetic species. This optical fiber-based setup enables the first acquisition of combined UV/Vis and NMR spectra in photocatalysis, as demonstrated on a conPET process. Furthermore, the broad applicability of combined UVNMR spectroscopy for light-induced processes is demonstrated on a structural and quantitative analysis of a photoswitch, including rate modulation and stabilization of transient species by temperature variation. Owing to the flexibility regarding the NMR hardware, temperature, and light sources, we expect wide-ranging applications of this setup in various research fields. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  13. SO2 Spectroscopy with A Tunable UV Laser

    Science.gov (United States)

    Morey, W. W.; Penney, C. M.; Lapp, M.

    1973-01-01

    A portion of the fluorescence spectrum of SO2 has been studied using a narrow wavelength doubled dye laser as the exciting source. One purpose of this study is to evaluate the use of SO2 resonance re-emission as a probe of SO2 in the atmosphere. When the SO2 is excited by light at 300.2 nm, for example, a strong reemission peak is observed which is Stokes-shifted from the incident light wavelength by the usual Raman shift (the VI symmetric vibration frequency 1150.5/cm ). The intensity of this peak is sensitive to small changes (.01 nm) in the incident wavelength. Measurements of the N2 quenching and self quenching of this re-emission have been obtained. Preliminary analysis of this data indicates that the quenching is weak but not negligible. The dye laser in our system is pumped by a pulsed N2 laser. Tuning 'and spectral narrowing are accomplished using a telescope-echelle grating combination. In a high power configuration the resulting pulses have a spectral width of about 5 x 10(exp -3) nm and a time duration of about 6 nsec. The echelle grating is rotated by a digital stepping motor, such that each step shifts the wavelength by 6 x 10(exp -4) nm. In addition to the tunable, narrow wavelength uv source and spectral analysis of the consequent re-emission, the system also provides time resolution of the re-emitted light to 6 nsec resolution. This capability is being used to study the lifetime of low pressure S02 fluorescence at different wavelengths and pressures.

  14. UV-Vis reflection spectroscopy under variable angle incidence at the air-liquid interface.

    Science.gov (United States)

    Roldán-Carmona, Cristina; Rubia-Payá, Carlos; Pérez-Morales, Marta; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

    2014-03-07

    The UV-Vis reflection spectroscopy (UV-Vis-RS) in situ at the air-liquid interface provides information about tilt and aggregation of chromophores in Langmuir monolayers. This information is particularly important given in most cases the chromophore is located at the polar region of the Langmuir monolayer. This region of the Langmuir monolayers has been hardly accessible by other experimental techniques. In spite of its enormous potential, the application of UV-Vis-RS has been limited mainly to reflection measurements under light normal incidence or at lower incidence angles than the Brewster angle. Remarkably, this technique is quite sensitive to the tilt of the chromophores at values of incidence angles close to or larger than the Brewster angle. Therefore, a novel method to obtain the order parameter of the chromophores at the air-liquid interface by using s- and p-polarized radiation at different incidence angles is proposed. This method allowed for the first time the experimental observation of the two components with different polarization properties of a single UV-Vis band at the air-liquid interface. The method of UV-Vis spectroscopy under variable angle incidence is presented as a new tool for obtaining rich detailed information on Langmuir monolayers.

  15. UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 1: basic principles and properties of tyrosine chromophore.

    Science.gov (United States)

    Antosiewicz, Jan M; Shugar, David

    2016-06-01

    Spectroscopic properties of tyrosine residues may be employed in structural studies of proteins. Here we discuss several different types of UV-Vis spectroscopy, like normal, difference and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, and corresponding optical properties of the tyrosine chromophore, phenol, which are used to study protein structure.

  16. Kinetic study of UV-irradiated amorphous sulfur by EPR spectroscopy

    International Nuclear Information System (INIS)

    El Mkami, H.; Smith, G.M.

    2005-01-01

    Electron paramagnetic resonance (EPR) spectroscopy is used to investigate UV-irradiation damage in amorphous sulfur by examining post-irradiation kinetics as a function of UV-exposure time. The kinetic study is described by first-order concurrent reactions where the sulfur, as reactant, undergoes two parallel processes leading to the formation of two distinct defects called S 1 * and S 2 *. The temperature dependence of the EPR intensities of the signals, related to these defects, is used in the kinetic study

  17. Very high resolution UV and X-ray spectroscopy and imagery of solar active regions

    Science.gov (United States)

    Bruner, M.; Brown, W. A.; Haisch, B. M.

    1987-01-01

    A scientific investigation of the physics of the solar atmosphere, which uses the techniques of high resolution soft X-ray spectroscopy and high resolution UV imagery, is described. The experiments were conducted during a series of three sounding rocket flights. All three flights yielded excellent images in the UV range, showing unprecedented spatial resolution. The second flight recorded the X-ray spectrum of a solar flare, and the third that of an active region. A normal incidence multi-layer mirror was used during the third flight to make the first astronomical X-ray observations using this new technique.

  18. Uncovering molecular relaxation processes with nonlinear spectroscopies in the deep UV

    International Nuclear Information System (INIS)

    West, Brantley A.; Molesky, Brian P.; Giokas, Paul G.; Moran, Andrew M.

    2013-01-01

    Highlights: • We discuss the outlook for multidimensional spectroscopies in the deep UV. • Photophysics are examined in small DNA components at cryogenic temperatures. • Wavepacket motions are detected in ring-opening systems with 2DUV spectroscopy. • Measurements of electronic wavepacket motions in molecules are proposed. - Abstract: Nonlinear laser spectroscopies in the deep UV spectral range are motivated by studies of biological systems and elementary processes in small molecules. This perspective article discusses recent technical advances in this area with a particular emphasis on diffractive optic based approaches to four-wave mixing spectroscopies. Applications to two classes of systems illustrate present experimental capabilities. First, experiments on DNA components at cryogenic temperatures are used to uncover features of excited state potential energy surfaces and vibrational cooling mechanisms. Second, sub-200 fs internal conversion processes and coherent wavepacket motions are investigated in cyclohexadiene and α-terpinene. Finally, we propose new experimental directions that combine methods for producing few-cycle UV laser pulses in noble gases with incoherent detection methods (e.g., photoionization) in experiments with time resolution near a singlefemtosecond. These measurements are motivated by knowledge of extremely fast non-adiabatic dynamics and the resolution of electronic wavepacket motions in molecules

  19. Correlated single-crystal electronic absorption spectroscopy and X-ray crystallography at NSLS beamline X26-C

    International Nuclear Information System (INIS)

    Orville, A.M.; Buono, R.; Cowan, M.; Heroux, A.; Shea-McCarthy, G.; Schneider, D.K.; Skinner, J.M.; Skinner, M.J.; Stoner-Ma, D.; Sweet, R.M.

    2011-01-01

    The research philosophy and new capabilities installed at NSLS beamline X26-C to support electronic absorption and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the electronic and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical absorption spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.

  20. The Classification of Ground Roasted Decaffeinated Coffee Using UV-VIS Spectroscopy and SIMCA Method

    Science.gov (United States)

    Yulia, M.; Asnaning, A. R.; Suhandy, D.

    2018-05-01

    In this work, an investigation on the classification between decaffeinated and non- decaffeinated coffee samples using UV-VIS spectroscopy and SIMCA method was investigated. Total 200 samples of ground roasted coffee were used (100 samples for decaffeinated coffee and 100 samples for non-decaffeinated coffee). After extraction and dilution, the spectra of coffee samples solution were acquired using a UV-VIS spectrometer (Genesys™ 10S UV-VIS, Thermo Scientific, USA) in the range of 190-1100 nm. The multivariate analyses of the spectra were performed using principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The SIMCA model showed that the classification between decaffeinated and non-decaffeinated coffee samples was detected with 100% sensitivity and specificity.

  1. Facile method for liquid-exfoliated graphene size prediction by UV-visible spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Zulhelmi, E-mail: helmie83@hotmail.com [Faculty of Manufacturing Engineering, Universiti Malaysia Pahang, 26600 Pekan, Pahang (Malaysia); Yusoh, Kamal, E-mail: kamal@ump.edu.my [Faculty of Chemical Engineering and Natural Resources, Universiti Malaysia Pahang, Lebuhraya Tun Razak, 26300 Kuantan, Pahang (Malaysia)

    2016-07-19

    In this work, an application of UV spectroscopy for facile prediction of liquid –exfoliated graphene size is discussed. Dynamic light scattering method was used to estimate the graphene flake size ( whilst UV spectroscopy measurement was carried out for extinction coefficient value (ε) determination. It was found that the value of (ε) decreased gradually as the graphene size was further reduced after intense sonication time (7h). This observation showed the influence of sonication time on electronic structure of graphene. A mathematical equation was derived from log-log graph for correlation between () and (ε) value. Both values can be expressed in a single equation as ( = (3.4 × 10{sup −2}) ε{sup 1.2}).

  2. UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry in the diagnostics of alopecia

    Science.gov (United States)

    Skomorokha, Diana P.; Pigoreva, Yulia N.; Salmin, Vladimir V.

    2016-04-01

    Development of optical biopsy methods has a great interest for medical diagnostics. In clinical and experimental studies it is very important to analyze blood circulation quickly and accurately, thereby laser Doppler flowmetry (LDF) is widely used. UV laser-induced fluorescence spectroscopy (UV LIFS) is express highly sensitive and widely-spread method with no destructive impact, high excitation selectivity and the possibility to use in highly scattering media. The goal of this work was to assess a correlation of UV laser-induced fluorescence spectroscopy and laser Doppler flowmetry parameters, and a possibility to identify or to differentiate various types of pathological changes in tissues according to their autofluorescence spectra. Three groups of patients with diffuse (symptomatic) alopecia, androgenic alopecia, and focal alopecia have been tested. Each groups consisted of not less than 20 persons. The measurements have been done in the parietal and occipital regions of the sculls. We used the original automated spectrofluorimeter to record autofluorescence spectra, and standard laser Doppler flowmeter BLF-21 (Transonic Systems, Inc., USA) to analyze the basal levels of blood circulation. Our results show that UV LIFS accurately distinguishes the zones with different types of alopecia. We found high correlation of the basal levels of blood circulation and the integrated intensity of autofluorescence in the affected tissue.

  3. UV-Raman spectroscopy, X-ray photoelectron spectroscopy, and temperature programmed desorption studies of model and bulk heterogeneous catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tewell, Craig Richmond [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    X-ray photoelectron spectroscopy (XPS) and Temperature Programmed Desorption (TPD) have been used to investigate the surface structure of model heterogeneous catalysts in ultra-high vacuum (UHV). UV-Raman spectroscopy has been used to probe the structure of bulk model catalysts in ambient and reaction conditions. The structural information obtained through UV-Raman spectroscopy has been correlated with both the UHV surface analysis and reaction results. The present day propylene and ethylene polymerization catalysts (Ziegler-Natta catalysts) are prepared by deposition of TiCl4 and a Al(Et)3 co-catalyst on a microporous Mg-ethoxide support that is prepared from MgCl2 and ethanol. A model thin film catalyst is prepared by depositing metallic Mg on a Au foil in a UHV chamber in a background of TiCl4 in the gas phase. XPS results indicate that the Mg is completely oxidized to MgCl2 by TiCl4 resulting in a thin film of MgCl2/TiClx, where x = 2, 3, and 4. To prepare an active catalyst, the thin film of MgCl2/TiClx on Au foil is enclosed in a high pressure cell contained within the UHV chamber and exposed to ~1 Torr of Al(Et)3.

  4. Effect of UV-A and UV-B irradiation on the metabolic profile of aqueous humor in rabbits analyzed by 1H NMR spectroscopy.

    Science.gov (United States)

    Tessem, May-Britt; Bathen, Tone F; Cejková, Jitka; Midelfart, Anna

    2005-03-01

    This study was conducted to investigate metabolic changes in aqueous humor from rabbit eyes exposed to either UV-A or -B radiation, by using (1)H nuclear magnetic resonance (NMR) spectroscopy and unsupervised pattern recognition methods. Both eyes of adult albino rabbits were irradiated with UV-A (366 nm, 0.589 J/cm(2)) or UV-B (312 nm, 1.667 J/cm(2)) radiation for 8 minutes, once a day for 5 days. Three days after the last irradiation, samples of aqueous humor were aspirated, and the metabolic profiles analyzed with (1)H NMR spectroscopy. The metabolic concentrations in the exposed and control materials were statistically analyzed and compared, with multivariate methods and one-way ANOVA. UV-B radiation caused statistically significant alterations of betaine, glucose, ascorbate, valine, isoleucine, and formate in the rabbit aqueous humor. By using principal component analysis, the UV-B-irradiated samples were clearly separated from the UV-A-irradiated samples and the control group. No significant metabolic changes were detected in UV-A-irradiated samples. This study demonstrates the potential of using unsupervised pattern recognition methods to extract valuable metabolic information from complex (1)H NMR spectra. UV-B irradiation of rabbit eyes led to significant metabolic changes in the aqueous humor detected 3 days after the last exposure.

  5. The use of UV-visible reflectance spectroscopy as an objective tool to evaluate pearl quality.

    Science.gov (United States)

    Agatonovic-Kustrin, Snezana; Morton, David W

    2012-07-01

    Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl's quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry.

  6. Crystallography: past and present

    Science.gov (United States)

    Hodeau, J.-L.; Guinebretiere, R.

    2007-12-01

    structure (chemical order, anisotropy, charge transfer, magnetic order) versus an external parameter like temperature, pressure, magnetic or electric field. Modern crystallography is also extended to the study of very small crystals, powders, ill-ordered or non-crystallized materials. Thus presently, crystallography is concerned with any solid that “scatters” an incident beam. Nevertheless, as quoted by A. Guinier, “the problems facing crystallographers have only changed, ... new ones have appeared which require reflection and imagination, ... and which in turn may still bring much joy to all those who like crystallography” [4]. Such developments open up crystallography to modern materials like artificial ones and nanostructures with low- and/or multi-scaled-periodicities and/or extremely small “crystal size” and to materials of the “real world”, with mixtures of phases and/or amorphous contribution and/or defects, a common characteristic of ancient materials analysed in patrimonial research. In our contribution we will show by selected examples that these improvements were allowed (i) by the use of powerful sources, apparatus and detectors which allow micro-diffraction, in-situ diffraction, spectroscopy, resonant scattering, inelastic scattering, coherent scattering, (ii) by the development of methods like diffraction anomalous fine structure (DAFS), pair distribution function (PDF), simulated annealing, single object reconstruction, (iii) by combination of scattering and spectroscopy and by combination of scattering and microscopy. Such combination of different approaches is very efficient and, as said by H. Curien at the IUCr Bordeaux Congress in 1990, “in crystallography, there is a constant alternation between the crystal space and its associated reciprocal space, ... the alternation between experiment and model building is another feature of crystallography activity ..., the crystallographer relies both on his computer and on his diffractometer

  7. [Experimental research of turbidity influence on water quality monitoring of COD in UV-visible spectroscopy].

    Science.gov (United States)

    Tang, Bin; Wei, Biao; Wu, De-Cao; Mi, De-Ling; Zhao, Jing-Xiao; Feng, Peng; Jiang, Shang-Hai; Mao, Ben-Jiang

    2014-11-01

    Eliminating turbidity is a direct effect spectroscopy detection of COD key technical problems. This stems from the UV-visible spectroscopy detected key quality parameters depend on an accurate and effective analysis of water quality parameters analytical model, and turbidity is an important parameter that affects the modeling. In this paper, we selected formazine turbidity solution and standard solution of potassium hydrogen phthalate to study the turbidity affect of UV--visible absorption spectroscopy detection of COD, at the characteristics wavelength of 245, 300, 360 and 560 nm wavelength point several characteristics with the turbidity change in absorbance method of least squares curve fitting, thus analyzes the variation of absorbance with turbidity. The results show, In the ultraviolet range of 240 to 380 nm, as the turbidity caused by particle produces compounds to the organics, it is relatively complicated to test the turbidity affections on the water Ultraviolet spectra; in the visible region of 380 to 780 nm, the turbidity of the spectrum weakens with wavelength increases. Based on this, this paper we study the multiplicative scatter correction method affected by the turbidity of the water sample spectra calibration test, this method can correct water samples spectral affected by turbidity. After treatment, by comparing the spectra before, the results showed that the turbidity caused by wavelength baseline shift points have been effectively corrected, and features in the ultraviolet region has not diminished. Then we make multiplicative scatter correction for the three selected UV liquid-visible absorption spectroscopy, experimental results shows that on the premise of saving the characteristic of the Ultraviolet-Visible absorption spectrum of water samples, which not only improve the quality of COD spectroscopy detection SNR, but also for providing an efficient data conditioning regimen for establishing an accurate of the chemical measurement methods.

  8. Developing a structure-function model for the cryptophyte phycoerythrin 545 using ultrahigh resolution crystallography and ultrafast laser spectroscopy.

    Science.gov (United States)

    Doust, Alexander B; Marai, Christopher N J; Harrop, Stephen J; Wilk, Krystyna E; Curmi, Paul M G; Scholes, Gregory D

    2004-11-12

    Cryptophyte algae differ from cyanobacteria and red algae in the architecture of their photosynthetic light harvesting systems, even though all three are evolutionarily related. Central to cryptophyte light harvesting is the soluble antenna protein phycoerythrin 545 (PE545). The ultrahigh resolution crystal structure of PE545, isolated from a unicellular cryptophyte Rhodomonas CS24, is reported at both 1.1A and 0.97A resolution, revealing details of the conformation and environments of the chromophores. Absorption, emission and polarized steady state spectroscopy (298K, 77K), as well as ultrafast (20fs time resolution) measurements of population dynamics are reported. Coupled with complementary quantum chemical calculations of electronic transitions of the bilins, these enable assignment of spectral absorption characteristics to each chromophore in the structure. Spectral differences between the tetrapyrrole pigments due to chemical differences between bilins, as well as their binding and interaction with the local protein environment are described. Based on these assignments, and considering customized optical properties such as strong coupling, a model for light harvesting by PE545 is developed which explains the fast, directional harvesting of excitation energy. The excitation energy is funnelled from four peripheral pigments (beta158,beta82) into a central chromophore dimer (beta50/beta61) in approximately 1ps. Those chromophores, in turn, transfer the excitation energy to the red absorbing molecules located at the periphery of the complex in approximately 4ps. A final resonance energy transfer step sensitizes just one of the alpha19 bilins on a time scale of 22ps. Furthermore, it is concluded that binding of PE545 to the thylakoid membrane is not essential for efficient energy transfer to the integral membrane chlorophyll a-containing complexes associated with PS-II.

  9. Advances in quantitative UV-visible spectroscopy for clinical and pre-clinical application in cancer.

    Science.gov (United States)

    Brown, J Quincy; Vishwanath, Karthik; Palmer, Gregory M; Ramanujam, Nirmala

    2009-02-01

    Methods of optical spectroscopy that provide quantitative, physically or physiologically meaningful measures of tissue properties are an attractive tool for the study, diagnosis, prognosis, and treatment of various cancers. Recent development of methodologies to convert measured reflectance and fluorescence spectra from tissue to cancer-relevant parameters such as vascular volume, oxygenation, extracellular matrix extent, metabolic redox states, and cellular proliferation have significantly advanced the field of tissue optical spectroscopy. The number of publications reporting quantitative tissue spectroscopy results in the UV-visible wavelength range has increased sharply in the past three years, and includes new and emerging studies that correlate optically measured parameters with independent measures such as immunohistochemistry, which should aid in increased clinical acceptance of these technologies.

  10. UV-visible and resonance Raman spectroscopy of halogen molecules in clathrate hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Janda, K.C.; Kerenskaya, G.; Goldsheleger, I.U.; Apkarian, V.A.; Fleischer, E.B. [California Univ., Irvine, CA (United States). Dept. of Chemistry

    2008-07-01

    Resonance Raman spectroscopy was used to study halogen clathrate hydrate solids. In particular, this paper presented an ultraviolet-visible spectra for a polycrystalline sample of chlorine clathrate hydrate and two single crystal samples of bromine clathrate hydrate. UV-visible spectroscopy was used to study the interactions between the halogen guest molecule and the host water lattice. The spectrum for chlorine hydrate had a strong temperature dependence, while the spectra for bromine clathrate hydrate single crystals had a stable cubic type 2 structure as well as a tetragonal structure. A metastable cubic type 1 structure was also observed. Resonance Raman spectroscopy showed how the molecules fit into the host cages. 25 refs., 2 tabs., 7 figs.

  11. UV Absorption Spectroscopy in Water-Filled Antiresonant Hollow Core Fibers for Pharmaceutical Detection.

    Science.gov (United States)

    Nissen, Mona; Doherty, Brenda; Hamperl, Jonas; Kobelke, Jens; Weber, Karina; Henkel, Thomas; Schmidt, Markus A

    2018-02-06

    Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological substances exhibit strong and characteristic absorption features at wavelengths shorter than 300 nm, UV spectroscopy presents a suitable approach for the quantitative identification of such water-contaminating species. However, current UV spectroscopic devices often show limited light-matter interaction lengths, demand sophisticated and bulky experimental infrastructure which is not compatible with microfluidics, and leave large fractions of the sample analyte unused. Here, we introduce the concept of UV spectroscopy in liquid-filled anti-resonant hollow core fibers, with large core diameters and lengths of approximately 1 m, as a means to overcome such limitations. This extended light-matter interaction length principally improves the concentration detection limit by two orders of magnitude while using almost the entire sample volume-that is three orders of magnitude smaller compared to cuvette based approaches. By integrating the fibers into an optofluidic chip environment and operating within the lowest experimentally feasible transmission band, concentrations of the application-relevant pharmaceutical substances, sulfamethoxazole (SMX) and sodium salicylate (SS), were detectable down to 0.1 µM (26 ppb) and 0.4 µM (64 ppb), respectively, with the potential to reach significantly lower detection limits for further device integration.

  12. UV Absorption Spectroscopy in Water-Filled Antiresonant Hollow Core Fibers for Pharmaceutical Detection

    Directory of Open Access Journals (Sweden)

    Mona Nissen

    2018-02-01

    Full Text Available Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological substances exhibit strong and characteristic absorption features at wavelengths shorter than 300 nm, UV spectroscopy presents a suitable approach for the quantitative identification of such water-contaminating species. However, current UV spectroscopic devices often show limited light-matter interaction lengths, demand sophisticated and bulky experimental infrastructure which is not compatible with microfluidics, and leave large fractions of the sample analyte unused. Here, we introduce the concept of UV spectroscopy in liquid-filled anti-resonant hollow core fibers, with large core diameters and lengths of approximately 1 m, as a means to overcome such limitations. This extended light-matter interaction length principally improves the concentration detection limit by two orders of magnitude while using almost the entire sample volume—that is three orders of magnitude smaller compared to cuvette based approaches. By integrating the fibers into an optofluidic chip environment and operating within the lowest experimentally feasible transmission band, concentrations of the application-relevant pharmaceutical substances, sulfamethoxazole (SMX and sodium salicylate (SS, were detectable down to 0.1 µM (26 ppb and 0.4 µM (64 ppb, respectively, with the potential to reach significantly lower detection limits for further device integration.

  13. Detection Limits of DLS and UV-Vis Spectroscopy in Characterization of Polydisperse Nanoparticles Colloids

    Directory of Open Access Journals (Sweden)

    Emilia Tomaszewska

    2013-01-01

    Full Text Available Dynamic light scattering is a method that depends on the interaction of light with particles. This method can be used for measurements of narrow particle size distributions especially in the range of 2–500 nm. Sample polydispersity can distort the results, and we could not see the real populations of particles because big particles presented in the sample can screen smaller ones. Although the theory and mathematical basics of DLS technique are already well known, little has been done to determine its limits experimentally. The size and size distribution of artificially prepared polydisperse silver nanoparticles (NPs colloids were studied using dynamic light scattering (DLS and ultraviolet-visible (UV-Vis spectroscopy. Polydisperse colloids were prepared based on the mixture of chemically synthesized monodisperse colloids well characterized by atomic force microscopy (AFM, transmission electron microscopy (TEM, DLS, and UV-Vis spectroscopy. Analysis of the DLS results obtained for polydisperse colloids reveals that several percent of the volume content of bigger NPs could screen completely the presence of smaller ones. The presented results could be extremely important from nanoparticles metrology point of view and should help to understand experimental data especially for the one who works with DLS and/or UV-Vis only.

  14. Application of in operando UV/Vis spectroscopy in lithium-sulfur batteries.

    Science.gov (United States)

    Patel, Manu U M; Dominko, Robert

    2014-08-01

    Application of UV/Vis spectroscopy for the qualitative and quantitative determination of differences in the mechanism of lithium-sulfur battery behavior is presented. With the help of catholytes prepared from chemically synthesized stoichiometric mixtures of lithium and sulfur, calibration curves for two different types of electrolyte can be constructed. First-order derivatives of UV/Vis spectra show five typical derivative peak positions in both electrolytes. In operando measurements show a smooth change in the UV/Vis spectra in the wavelength region between λ=650 and 400 nm. Derivatives are in agreement with derivative peak positions observed with catholytes. Recalculation of normalized reflections of UV/Vis spectra obtained in operando mode enable the formation of polysulfides and their concentrations to be followed. In such a way, it is possible to distinguish differences in the mechanism of polysulfide shuttling between two electrolytes and to correlate differences in capacity fading. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Application of isothermal calorimetry and uv spectroscopy for stability monitoring of pentaerythritol tetranitrate

    International Nuclear Information System (INIS)

    Dosser, L.R.; Pickard, J.M.

    1992-01-01

    Thermal stabilities for a series of pentaerythritol-tetranitrate (PETN) samples with variable surf ace areas were monitored by isothermal calorimetry and UV spectroscopy over the temperature range of 363 to 408 K. Isothermal induction times measured with constant volume calorimetry under an air atmosphere and No evolution rates monitored by UV absorbance at 213 nm under vacuum correlated with the PETN surface area at temperatures equal to or exceeding 383 K. Rate data measured at 383 K are in accord with predictions based on detailed kinetic modeling. Below 383 K, NO evolution data suggested that additional geometric factors may be significant in controlling PETN stability. Mechanisms for influencing surface area upon the rate-determining step are addressed

  16. Crystallography: past and present

    International Nuclear Information System (INIS)

    Hodeau, J.L.; Guinebretiere, R.

    2007-01-01

    In the 19th century, crystallography referred to the study of crystal shapes. A breakthrough appeared in 1912 with the use of X-rays by M. von Laue and W.H. and W.L. Bragg. This experimental development allowed the determination of the atomic content of each unit cell constituting the crystal and defined a crystal as ''any solid in which an atomic pattern is repeated periodically in three dimensions, that is, any solid that ''diffracts'' an incident X-ray beam''. Mathematical tools like the Patterson methods, the direct methods, were developed. Furthermore the development of new sources of neutrons, electrons and synchrotron X-rays allowed the studies of complex compounds like large macromolecules in biology. In our contribution we show by selected examples that these improvements were allowed (i) by the use of powerful sources, apparatus and detectors which allow micro-diffraction, in-situ diffraction, spectroscopy, resonant scattering, inelastic scattering, coherent scattering, (ii) by the development of methods like diffraction anomalous fine structure (DAFS), pair distribution function (PDF), simulated annealing, single object reconstruction, (iii) by combination of scattering and spectroscopy and by combination of scattering and microscopy. (orig.)

  17. Racemic DNA Crystallography

    OpenAIRE

    Mandal , Pradeep K.; Collie , Gavin W.; Kauffmann , Brice; Huc , Ivan

    2014-01-01

    International audience; Racemates increase the chances of crystallization by allowing molecular contacts to be formed in a greater number of ways. With the advent of protein synthesis, the production of protein racemates and racemic-protein crystallography are now possible. Curiously, racemic DNA crystallography had not been investigated despite the commercial availability of Land D-deoxyribo-oligonucleotides. Here, we report a study into racemic DNA crystallography showing the strong propens...

  18. Oligophenylenevinylenes in spatially confined nanochannels: Monitoring intermolecular interactions by UV/Vis and Raman spectroscopy

    DEFF Research Database (Denmark)

    Aloshyna, Mariya; Medina, Begona Milian; Poulsen, Lars

    2008-01-01

    -guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum-chemical calculations. In stark contrast to thin films where preferential side-by-side orientation leads to quenching...... of photoluminescence (PL) via non-emissive traps, the ICs are found to be attractive materials for opto-electronic applications: they offer high chromophore concentrations, but at the same time behave as quasi-isolated entities of tightly packed, well-oriented objects with high PL quantum yields and the possibility...

  19. Sulphured Polyacrylonitrile Composite Analysed by in operando UV-Visible Spectroscopy and 4-electrode Swagelok Cell.

    Science.gov (United States)

    Dominko, Robert; Patel, Manu U M; Bele, Marjan; Pejovnik, Stane

    2016-01-01

    The electrochemical characteristics of sulfurized polyacrylonitrile composite (PAN/S) cathodes were compared with the commonly used carbon/S-based composite material. The difference in the working mechanism of these composites was examined. Analytical investigations were performed on both kinds of cathode electrode composites by using two reliable analytical techniques, in-situ UV-Visible spectroscopy and a four-electrode Swagelok cell. This study differentiates the working mechanisms of PAN/S composites from conventional elemental sulphur/carbon composite and also sheds light on factors that could be responsible for capacity fading in the case of PAN/S composites.

  20. Development of pulsed UV lasers and their application in laser spectroscopy

    International Nuclear Information System (INIS)

    De la Rosa, M I; Perez, C; Gruetzmacher, K; GarcIa, D; Bustillo, A

    2011-01-01

    The application of two-photon laser spectroscopy to plasma diagnostics requires tuneable UV-laser spectrometers providing: some mJ pulse energy at ns time scale with spectral quality close to Fourier Transform Limit, good pulse to pulse reproducibility and tuning linearity. We report about two different systems, a first laser specially optimized for the radiation at 243 nm, which is required for the 1S-2S two photon transition of atomic hydrogen, and a second one generating 205 nm suited for the transition 1S - 3S/3D.

  1. Evolution of microstructure of epoxy coating during UV degradation progress studied by slow positron annihilation spectroscopy and electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Liu, Fuwei; Yin, Mingxi; Xiong, Bangyun; Zheng, Feng; Mao, Wenfeng; Chen, Zhe; He, Chunqing; Zhao, Xipo; Fang, Pengfei

    2014-01-01

    Graphical abstract: - Highlights: • Decrements in S value and water uptake coefficient confirm the post-cure process. • Molecular chain scission leads to the formation of microporous structure. • The formation of an aged layer with high density is verified by EIS. - Abstract: Evolution of chemical functional groups, microstructure and water barrier properties of a polyamide-cured epoxy (diglycidyl ether of bisphenol-A epoxy resin, DGEBA) coating during ultraviolet A (UV-A) photo-oxidative aging is systematically investigated. At the early stage of aging, decrements of S parameter and water uptake coefficient indicate the formation of a more compact structure induced by the post-curing process. After 208 hours (h) of UV irradiation, a novel time constant at relatively high frequency (3.5 × 10 2 Hz) appears in the electrochemical impedance spectroscopy (EIS) spectra suggesting that a microporous layer generates near the surface of DGEBA film. With the increase in irradiation time, overlap of two time constants at frequencies around 18 Hz and 3.7 × 10 3 Hz is observed after 1.33 h of immersion, indicating that the micropores grow towards the bulk and form more characteristic layers with microporous structures. After irradiation for 399 h, a low S parameter region near the sample surface is observed, which implies that a surface layer with low free volume may have formed. With longer exposure, EIS results also reveal that the water barrier property of the coating can be improved, which confirms the formation of the denser surface layer near the surface as a result of radical recombination during UV-A treatment

  2. Investigation of L(+)-Ascorbic Acid with Raman Spectroscopy in Visible and UV Light

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    2015-01-01

    Abstract: Raman spectroscopy investigations of l(+)-ascorbic acid and its mono- and di-deprotonated anions (AH(-) and A(2-)) are reviewed and new measurements reported with several wavelengths, 229, 244, 266, 488, and 532nm. Results are interpreted, assisted by new DFT/B3LYP quantum chemical calc......). Relatively weak preresonance enhancement was seen for A(2-) when excitation was done with 229nm UV light, allowing water bands to become observable as for normal visible light Raman spectra....... calculations with 6-311++G(d,p) basis sets for several conformations of ascorbic acid and the anions. Raman spectra were measured during titration with NaOH base in an oxygen-poor environment to avoid fluorescence when solutions were alkaline. The ultraviolet (UV) absorption band for ascorbic acid in aqueous......cm(-1). Finally, for the ascorbate di-anion, absorption was found at similar to 298.4nm with molar absorptivity of similar to 7,000 L mol(-1) cm(-1) and below similar to 220nm. With UV light (244 and 266nm), strongly basic solutions gave pronounced Raman resonance enhancement at similar to 1556cm(-1...

  3. Quantifying tropical peatland dissolved organic carbon (DOC) using UV-visible spectroscopy.

    Science.gov (United States)

    Cook, Sarah; Peacock, Mike; Evans, Chris D; Page, Susan E; Whelan, Mick J; Gauci, Vincent; Kho, Lip Khoon

    2017-05-15

    UV-visible spectroscopy has been shown to be a useful technique for determining dissolved organic carbon (DOC) concentrations. However, at present we are unaware of any studies in the literature that have investigated the suitability of this approach for tropical DOC water samples from any tropical peatlands, although some work has been performed in other tropical environments. We used water samples from two oil palm estates in Sarawak, Malaysia to: i) investigate the suitability of both single and two-wavelength proxies for tropical DOC determination; ii) develop a calibration dataset and set of parameters to calculate DOC concentrations indirectly; iii) provide tropical researchers with guidance on the best spectrophotometric approaches to use in future analyses of DOC. Both single and two-wavelength model approaches performed well with no one model significantly outperforming the other. The predictive ability of the models suggests that UV-visible spectroscopy is both a viable and low cost method for rapidly analyzing DOC in water samples immediately post-collection, which can be important when working at remote field sites with access to only basic laboratory facilities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. Study of high density polyethylene under UV irradiation or mechanical stress by fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Douminge, L.

    2010-05-01

    Due to their diversity and their wide range of applications, polymers have emerged in our environment. For technical applications, these materials can be exposed to aggressive environment leading to an alteration of their properties. The effects of this degradation are linked to the concept of life duration, corresponding to the time required for a property to reach a threshold below which the material becomes unusable. Monitoring the ageing of polymer materials constitute a major challenge. Fluorescence spectroscopy is a technique able to provide accurate information concerning this issue. In this study, emphasis was placed on the use of fluorescence spectroscopy to study the phenomena involved in either the UV radiation or mechanical stresses of a polymer. In the case of high density polyethylene, the lack of intrinsic fluorescent signal leads to the use of a dye. This dye gives a fluorescent response depending on its microenvironment. All modifications in the macromolecular chain generate a shift of the fluorescent peak. This work can be dissociated in two major parts, on one hand the influence of UV aging on the fluorescent response and in another hand the influence of mechanical stresses. In the first part, complementary analyses like FTIR or DSC are used to correlate fluorescent results with known photo degradation mechanisms. The results show the great sensibility of the technique to the microstructural rearrangement in the polymer. In the second part, the dependence between the stress and the fluorescence emission gives opportunity to evaluate internal stresses in the material during cyclic solicitations. (author)

  5. Classification of Argentinean Sauvignon blanc wines by UV spectroscopy and chemometric methods.

    Science.gov (United States)

    Azcarate, Silvana Mariela; Cantarelli, Miguel Ángel; Pellerano, Roberto Gerardo; Marchevsky, Eduardo Jorge; Camiña, José Manuel

    2013-03-01

    Argentina is an important worldwide wine producer. In this country, there are several recognizable provinces that produce Sauvignon blanc wines: Neuquén, Río Negro, Mendoza, and San Juan. The analysis of the provenance of these white wines is complex and requires the use of expensive and time-consuming techniques. For this reason, this work discusses the determination of the provenance of Argentinean Sauvignon blanc wines by the use of UV spectroscopy and chemometric methods, such as principal component analysis (PCA), cluster analysis (CA), linear discriminant analysis (LDA), and partial least square discriminant analysis (PLS-DA). The proposed method requires low-cost equipment and short-time analysis in comparison with other techniques. The results are in very good agreement with results based on the geographical origin of Sauvignon blanc wines. This manuscript describes a method to determine the geographical origin of Sauvignon wines from Argentina. The main advantage of this method is the use of nonexpensive techniques, such as UV-Vis spectroscopy. © 2013 Institute of Food Technologists®

  6. Tenth International Colloquium on UV and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas

    Science.gov (United States)

    Silver, Eric H.; Kahn, Steven M.

    UV and X-ray spectroscopy of astrophysical and laboratory plasmas draws interest from many disciplines. Contributions from international specialists are collected together in this book from a timely recent conference. In astrophysics, the Hubble Space Telescope, Astro 1 and ROSAT observatories are now providing UV and X-ray spectra and images of cosmic sources in unprecedented detail, while the Yohkoh mission recently collected superb data on the solar corona. In the laboratory, the development of ion-trap facilities and novel laser experiments are providing vital new data on high temperature plasmas. Recent innovations in the technology of spectroscopic instrumentation are discussed. These papers constitute an excellent up-to-date review of developments in short-wavelength spectroscopy and offer a solid introduction to its theoretical and experimental foundations. These proceedings give an up-to-date review of developments in short-wavelength spectroscopy and offer a solid introduction to its theoretical and experimental foundations. Various speakers presented some of the first results from the high resolution spectrograph on the Hubble Space Telescope, the high sensitivity far ultraviolet and X-ray spectrometers of the ASTRO 1 Observatory, the imaging X-ray spectrometer on the ROSAT Observatory, and the high resolution solar X-ray spectrometer on Yohkoh. The development of ion trap devices had brought about a revolution in laboratory investigations of atomic processes in highly charged atoms. X-ray laser experiments had not only yielded considerable insight into electron ion interactions in hot dense plasmas, but also demonstrated the versatility of laser plasmas as laboratory X-ray sources. Such measurements also motivated and led to refinements in the development of large-scale atomic and molecular codes. On the instrumental side, the design and development of the next series of very powerful short wavelength observatories had generated a large number of

  7. Chemometric classification of Chinese lager beers according to manufacturer based on data fusion of fluorescence, UV and visible spectroscopies.

    Science.gov (United States)

    Tan, Jin; Li, Rong; Jiang, Zi-Tao

    2015-10-01

    We report an application of data fusion for chemometric classification of 135 canned samples of Chinese lager beers by manufacturer based on the combination of fluorescence, UV and visible spectroscopies. Right-angle synchronous fluorescence spectra (SFS) at three wavelength difference Δλ=30, 60 and 80 nm and visible spectra in the range 380-700 nm of undiluted beers were recorded. UV spectra in the range 240-400 nm of diluted beers were measured. A classification model was built using principal component analysis (PCA) and linear discriminant analysis (LDA). LDA with cross-validation showed that the data fusion could achieve 78.5-86.7% correct classification (sensitivity), while those rates using individual spectroscopies ranged from 42.2% to 70.4%. The results demonstrated that the fluorescence, UV and visible spectroscopies complemented each other, yielding higher synergic effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Underresolved absorption spectroscopy of OH radicals in flames using broadband UV LEDs

    Science.gov (United States)

    White, Logan; Gamba, Mirko

    2018-04-01

    A broadband absorption spectroscopy diagnostic based on underresolution of the spectral absorption lines is evaluated for the inference of species mole fraction and temperature in combustion systems from spectral fitting. The approach uses spectrally broadband UV light emitting diodes and leverages low resolution, small form factor spectrometers. Through this combination, the method can be used to develop high precision measurement sensors. The challenges of underresolved spectroscopy are explored and addressed using spectral derivative fitting, which is found to generate measurements with high precision and accuracy. The diagnostic is demonstrated with experimental measurements of gas temperature and OH mole fraction in atmospheric air/methane premixed laminar flat flames. Measurements exhibit high precision, good agreement with 1-D flame simulations, and high repeatability. A newly developed model of uncertainty in underresolved spectroscopy is applied to estimate two-dimensional confidence regions for the measurements. The results of the uncertainty analysis indicate that the errors in the outputs of the spectral fitting procedure are correlated. The implications of the correlation between uncertainties for measurement interpretation are discussed.

  9. Ultrafast pre-breakdown dynamics in Al₂O₃SiO₂ reflector by femtosecond UV laser spectroscopy.

    Science.gov (United States)

    Du, Juan; Li, Zehan; Xue, Bing; Kobayashi, Takayoshi; Han, Dongjia; Zhao, Yuanan; Leng, Yuxin

    2015-06-29

    Ultrafast carrier dynamics in Al2O3/SiO2 high reflectors has been investigated by UV femtosecond laser. It is identified by laser spectroscopy that, the carrier dynamics contributed from the front few layers of Al2O3 play a dominating role in the initial laser-induced damage of the UV reflector. Time-resolved reflection decrease after the UV excitation is observed, and conduction electrons is found to relaxed to a mid-gap defect state locating about one photon below the conduction band . To interpret the laser induced carrier dynamics further, a theoretical model including electrons relaxation to a mid-gap state is built, and agrees very well with the experimental results.. To the best of our knowledge, this is the first study on the pre-damage dynamics in UV high reflector induced by femtosecond UV laser.

  10. Attenuated total reflection UV spectroscopy for simultaneous analysis of alkali, sulphide and dissolved lignin in pulping liquors

    International Nuclear Information System (INIS)

    Chai, X.S.; Zhu, J.Y.; Luo, Q.; Li, J.

    2003-01-01

    This study experimentally demonstrated attenuated total reflection (ATR) ultraviolet (UV) spectroscopy for rapid and simultaneous determination of the concentrations of hydroxide, sulphide and dissolved lignin in kraft pulping liquors. A multivariate partial least squares fitting procedure (using commercially available software) was employed to obtain the species concentrations from the measured absorption spectra of the pulping liquors. Good agreements between ATR-UV measured species concentrations and those obtained by reference methods (titration for hydroxide and sulphide and conventional UV absorption for dissolved lignin) were achieved. (author)

  11. Simultaneous UV Imaging and Raman Spectroscopy for the Measurement of Solvent-Mediated Phase Transformations During Dissolution Testing

    DEFF Research Database (Denmark)

    Ostergaard, Jesper; Wu, Jian; Naelapää, Kaisa

    2014-01-01

    The current work reports the simultaneous use of UV imaging and Raman spectroscopy for detailed characterization of drug dissolution behavior including solid-state phase transformations during dissolution. The dissolution of drug substances from compacts of sodium naproxen in 0.1 HCl as well as t...... of UV imaging and Raman spectroscopy offers a detailed characterization of drug dissolution behavior in a time-effective and sample-sparing manner. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:1149-1156, 2014....

  12. Discrimination of whisky brands and counterfeit identification by UV-Vis spectroscopy and multivariate data analysis.

    Science.gov (United States)

    Martins, Angélica Rocha; Talhavini, Márcio; Vieira, Maurício Leite; Zacca, Jorge Jardim; Braga, Jez Willian Batista

    2017-08-15

    The discrimination of whisky brands and counterfeit identification were performed by UV-Vis spectroscopy combined with partial least squares for discriminant analysis (PLS-DA). In the proposed method all spectra were obtained with no sample preparation. The discrimination models were built with the employment of seven whisky brands: Red Label, Black Label, White Horse, Chivas Regal (12years), Ballantine's Finest, Old Parr and Natu Nobilis. The method was validated with an independent test set of authentic samples belonging to the seven selected brands and another eleven brands not included in the training samples. Furthermore, seventy-three counterfeit samples were also used to validate the method. Results showed correct classification rates for genuine and false samples over 98.6% and 93.1%, respectively, indicating that the method can be helpful for the forensic analysis of whisky samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy.

    Science.gov (United States)

    Śliwińska, Magdalena; Garcia-Hernandez, Celia; Kościński, Mikołaj; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Śliwińska-Bartkowiak, Małgorzata; Jurga, Stefan; Garcia-Cabezon, Cristina; Rodriguez-Mendez, Maria Luz

    2016-10-09

    The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin-Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content-the most important parameters to be measured in this type of liqueurs.

  14. Electronic structure and thermal decomposition of 5-aminotetrazole studied by UV photoelectron spectroscopy and theoretical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Rui M., E-mail: ruipinto@fct.unl.pt [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Dias, Antonio A.; Costa, Maria L. [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2011-03-18

    Graphical abstract: Gas-phase UV photoelectron spectrum of the thermal decomposition of 5-aminotetrazole (5ATZ), obtained at 245 {sup o}C, and mechanism underlying the thermal dissociation of 2H-5ATZ. Research highlights: {yields} Electronic structure of 5ATZ studied by photoelectron spectroscopy. {yields} Gas-phase 5-ATZ exists mainly as the 2H-tautomer. {yields} Thermal decomposition of 5ATZ gives N{sub 2}, NH{sub 2}CN, HN{sub 3} and HCN, at 245 {sup o}C. {yields} HCN can be originated from a carbene intermediate. - Abstract: The electronic properties and thermal decomposition of 5-aminotetrazole (5ATZ) are investigated using UV photoelectron spectroscopy (UVPES) and theoretical calculations. Simulated spectra of both 1H- and 2H-5ATZ, based on electron propagator methods, are produced in order to study the relative gas-phase tautomer population. The thermal decomposition results are rationalized in terms of intrinsic reaction coordinate (IRC) calculations. 5ATZ yields a HOMO ionization energy of 9.44 {+-} 0.04 eV and the gas-phase 5ATZ assumes mainly the 2H-form. The thermal decomposition of 5ATZ leads to the formation of N{sub 2}, HN{sub 3} and NH{sub 2}CN as the primary products, and HCN from the decomposition of a intermediate CH{sub 3}N{sub 3} compound. The reaction barriers for the formation of HN{sub 3} and N{sub 2} from 2H-5ATZ are predicted to be {approx}228 and {approx}150 kJ/mol, at the G2(MP2) level, respectively. The formation of HCN and HNNH from the thermal decomposition of a CH{sub 3}N{sub 3} carbene intermediate is also investigated.

  15. Racemic DNA crystallography.

    Science.gov (United States)

    Mandal, Pradeep K; Collie, Gavin W; Kauffmann, Brice; Huc, Ivan

    2014-12-22

    Racemates increase the chances of crystallization by allowing molecular contacts to be formed in a greater number of ways. With the advent of protein synthesis, the production of protein racemates and racemic-protein crystallography are now possible. Curiously, racemic DNA crystallography had not been investigated despite the commercial availability of L- and D-deoxyribo-oligonucleotides. Here, we report a study into racemic DNA crystallography showing the strong propensity of racemic DNA mixtures to form racemic crystals. We describe racemic crystal structures of various DNA sequences and folded conformations, including duplexes, quadruplexes, and a four-way junction, showing that the advantages of racemic crystallography should extend to DNA. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Cold, Gas-Phase UV and IR Spectroscopy of Protonated Leucine Enkephalin and its Analogues

    Science.gov (United States)

    Burke, Nicole L.; Redwine, James; Dean, Jacob C.; McLuckey, Scott A.; Zwier, Timothy S.

    2014-06-01

    The conformational preferences of peptide backbones and the resulting hydrogen bonding patterns provide critical biochemical information regarding the structure-function relationship of peptides and proteins. The spectroscopic study of cryogenically-cooled peptide ions in a mass spectrometer probes these H-bonding arrangements and provides information regarding the influence of a charge site. Leucine enkephalin, a biologically active endogenous opiod peptide, has been extensively studied as a model peptide in mass spectrometry. This talk will present a study of the UV and IR spectroscopy of protonated leucine enkephalin [YGGFL+H]+ and two of its analogues: the sodiated [YGGFL+Na]+ and C-terminally methyl esterified [YGGFL-OMe+H]+ forms. All experiments were performed in a recently completed multi-stage mass spectrometer outfitted with a cryocooled ion trap. Ions are generated via nano-electrospray ionization and the analyte of interest is isolated in a linear ion trap. The analyte ions are trapped in a 22-pole ion trap held at 5 K by a closed cycle helium cryostat and interrogated via UV and IR lasers. Photofragments are trapped and isolated in a second LIT and mass analyzed. Double-resonance UV and IR methods were used to assign the conformation of [YGGFL+H]+, using the NH/OH stretch, Amide I, and Amide II regions of the infrared spectrum. The assigned structure contains a single backbone conformation at vibrational/rotational temperatures of 10 K held together with multiple H-bonds that self-solvate the NH3+ site. A "proton wire" between the N and C termini reinforces the H-bonding activity of the COO-H group to the F-L peptide bond, whose cleavage results in formation of the b4 ion, which is a prevalent, low-energy fragmentation pathway for [YGGFL+H]+. The reinforced H-bonding network in conjunction with the mobile proton theory may help explain the prevalence of the b4 pathway. In order to elucidate structural changes caused by modifying this H-bonding activity

  17. UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

    Science.gov (United States)

    Hansen, Christopher S.; Kirk, Benjamin B.; Blanksby, Stephen J.; O'Hair, Richard. A. J.; Trevitt, Adam J.

    2013-06-01

    UV-vis photodissociation action spectroscopy is becoming increasingly prevalent because of advances in, and commercial availability of, ion trapping technologies and tunable laser sources. This study outlines in detail an instrumental arrangement, combining a commercial ion-trap mass spectrometer and tunable nanosecond pulsed laser source, for performing fully automated photodissociation action spectroscopy on gas-phase ions. The components of the instrumentation are outlined, including the optical and electronic interfacing, in addition to the control software for automating the experiment and performing online analysis of the spectra. To demonstrate the utility of this ensemble, the photodissociation action spectra of 4-chloroanilinium, 4-bromoanilinium, and 4-iodoanilinium cations are presented and discussed. Multiple photoproducts are detected in each case and the photoproduct yields are followed as a function of laser wavelength. It is shown that the wavelength-dependent partitioning of the halide loss, H loss, and NH3 loss channels can be broadly rationalized in terms of the relative carbon-halide bond dissociation energies and processes of energy redistribution. The photodissociation action spectrum of (phenyl)Ag2 + is compared with a literature spectrum as a further benchmark.

  18. Combined operando Raman/UV-Vis-NIR spectroscopy as a tool to study supported metal oxide catalysts at work

    NARCIS (Netherlands)

    Tinnemans, Stanislaus Josephus

    2006-01-01

    A novel set-up has been developed in which two complementary spectroscopic techniques, namely operando Raman and UV-Vis-NIR spectroscopy, are combined. With this set-up it is possible to characterize catalytic materials under reaction conditions (high temperature, normal pressure) and in this way on

  19. Time-dependent study of the exfoliation process of carbon nanotubes in aqueous dispersions by using UV-visible spectroscopy

    NARCIS (Netherlands)

    Grossiord, N.; Regev, O.; Loos, J.; Meuldijk, J.; Koning, C.E.

    2005-01-01

    In this paper we demonstrate that the sonication-driven exfoliation of aggregates and bundles of single-wall carbon nanotubes (SWNTs) in an aqueous surfactant solution can be easily monitored by UV-vis spectroscopy. The different stages of the exfoliation process were directly visualized by

  20. Inline UV-Vis spectroscopy to monitor and optimize cleaning-in-place (CIP) of whey filtration plants

    DEFF Research Database (Denmark)

    Berg, Thilo Heinz Alexander; Ottosen, Niels; van der Berg, Franciscus Winfried J.

    2017-01-01

    used for every day. We investigated the capability of inline UV-Vis spectroscopy to elucidate the dynamics of CIP of membrane filtration plants as a gateway to control and optimize the process. For this investigation aged membranes that had been used for industrial ultrafiltration of whey were...

  1. Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study

    Czech Academy of Sciences Publication Activity Database

    Shaffer, C. J.; Martens, J.; Marek, Aleš; Oomens, J.; Tureček, F.

    2016-01-01

    Roč. 27, č. 7 (2016), s. 1176-1185 ISSN 1044-0305 Institutional support: RVO:61388963 Keywords : peptide ions * electron transfer dissociation * photoleucine label * near-UV photodissociation * infrared multiphoton dissociation action spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.786, year: 2016

  2. Styrene oligomerization as a molecular probe reaction for zeolite acidity: a UV-Vis spectroscopy and DFT study

    NARCIS (Netherlands)

    Buurmans, I.L.C.; Pidko, E.A.; Groot, de J.M.; Stavitski, E.; Santen, van R.A.; Weckhuysen, B.M.

    2010-01-01

    A series of H-ZSM-5 crystallites with different framework Si/Al ratios was studied by analyzing the kinetics and reaction mechanism of the oligomerization of 4-fluorostyrene as molecular probe reaction for Brønsted acidity. The formation of carbocationic species was followed by UV-Vis spectroscopy.

  3. A conformational study of protonated noradrenaline by UV-UV and IR dip double resonance laser spectroscopy combined with an electrospray and a cold ion trap method.

    Science.gov (United States)

    Wako, Hiromichi; Ishiuchi, Shun-Ichi; Kato, Daichi; Féraud, Géraldine; Dedonder-Lardeux, Claude; Jouvet, Christophe; Fujii, Masaaki

    2017-05-03

    The conformer-selected ultraviolet (UV) and infrared (IR) spectra of protonated noradrenaline were measured using an electrospray/cryogenic ion trap technique combined with photo-dissociation spectroscopy. By comparing the UV photo dissociation (UVPD) spectra with the UV-UV hole burning (HB) spectra, it was found that five conformers coexist under ultra-cold conditions. Based on the spectral features of the IR dip spectra of each conformer, two different conformations on the amine side chain were identified. Three conformers (group I) were assigned to folded and others (group II) to extended structures by comparing the observed IR spectra with the calculated ones. Observation of the significantly less-stable extended conformers strongly suggests that the extended structures are dominant in solution and are detected in the gas phase by kinetic trapping. The conformers in each group are assignable to rotamers of OH orientations in the catechol ring. By comparing the UV-UV HB spectra and the calculated Franck-Condon spectra obtained by harmonic vibrational analysis of the S 1 state, with the aid of relative stabilization energies of each conformer in the S 0 state, the absolute orientations of catechol OHs of the observed five conformers were successfully determined. It was found that the 0-0 transition of one folded conformer is red-shifted by about 1000 cm -1 from the others. The significant red-shift was explained by a large contribution of the πσ* state to S 1 in the conformer in which an oxygen atom of the meta-OH group is close to the ammonium group.

  4. Using Deep UV Raman Spectroscopy to Identify In Situ Microbial Activity

    Science.gov (United States)

    Sapers, H. M.; Wanger, G.; Amend, J.; Orphan, V. J.; Bhartia, R.

    2017-12-01

    Microbial communities living in close association with lithic substrates play a critical role in biogeochemical cycles. Understanding the interactions between microorganisms and their abiotic substrates requires knowledge of microbial activity. Identifying active cells adhered to complex environmental substrates, especially in low biomass systems, remains a challenge. Stable isotope probing (SIP) provides a means to trace microbial activity in environmental systems. Active members of the community take up labeled substrates and incorporate the labels into biomolecules that can be detected through downstream analyses. Here we show for the first time that Deep UV (248 nm) Raman spectroscopy can differentiate microbial cells labeled with stable isotopes. Previous studies have used Raman spectroscopy with a 532 nm source to identify active bacterial cells by measuring a Raman shift between peaks corresponding to amino acids incorporating 13C compared to controls. However, excitation at 532 nm precludes detection on complex substrates due to high autofluorescence of native minerals. Excitation in the DUV range offers non-destructive imaging on mineral surfaces - retaining critical contextual information. We prepared cultures of E. coli grown in 50 atom% 13C glucose spotted onto Al wafers to test the ability of DUV Raman spectroscopy to differentiate labeled and unlabeled cells. For the first time, we are able to demonstrate a distinct and repeatable shift between cells grown in labeled media and unlabeled media when imaged on Al wafers with DUV Raman spectroscopy. The Raman spectra are dominated by the characteristic Raman bands of guanine. The dominant marker peak for guanine attributed to N7-C8 and C8-N9 ring stretching and C8-H in-plane bending, is visible at 1480 cm-1 in the unlabeled cells and is blue-shifted by 20 wavenumbers to 1461 cm-1 in the labeled cells. The ability of DUV Raman to effectively identify regions containing cells that have incorporated isotopic

  5. UV-Vis, infrared, and mass spectroscopy of electron irradiated frozen oxygen and carbon dioxide mixtures with water

    International Nuclear Information System (INIS)

    Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

    2014-01-01

    Ozone has been detected on the surface of Ganymede via observation of the Hartley band through the use of ultraviolet spectroscopy and is largely agreed upon to be formed by radiolytic processing via interaction of magnetospheric energetic ions and/or electrons with oxygen-bearing ices on Ganymede's surface. Interestingly, a clearly distinct band near 300 nm within the shoulder of the UV-Vis spectrum of Ganymede was also observed, but currently lacks an acceptable physical or chemical explanation. Consequently, the primary motivation behind this work was the collection of UV-Vis absorption spectroscopy of ozone formation by energetic electron bombardment of a variety of oxygen-bearing ices (oxygen, carbon dioxide, water) relevant to this moon as well as other solar system. Ozone was indeed synthesized in pure ices of molecular oxygen, carbon dioxide and a mixture of water and oxygen, in agreement with previous studies. The Hartley band of the ozone synthesized in these ice mixtures was observed in the UV-Vis spectra and compared with the spectrum of Ganymede. In addition, a solid state ozone absorption cross section of 6.0 ± 0.6 × 10 –17 cm 2 molecule –1 was obtained from the UV-Vis spectral data. Ozone was not produced in the irradiated carbon dioxide-water mixtures; however, a spectrally 'red' UV continuum is observed and appears to reproduce well what is observed in a large number of icy moons such as Europa.

  6. Development of an online UV–visible microspectrophotometer for a macromolecular crystallography beamline

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Nobutaka, E-mail: nobutaka.shimizu@kek.jp [SPring-8/JASRI, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Shimizu, Tetsuya [RIKEN SPring-8 Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Baba, Seiki; Hasegawa, Kazuya [SPring-8/JASRI, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Yamamoto, Masaki [RIKEN SPring-8 Center, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Kumasaka, Takashi [SPring-8/JASRI, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2013-11-01

    An online UV–visible microspectrophotometer has been developed for the macromolecular crystallography beamline at SPring-8. Details of this spectrophotometer are reported. Measurement of the UV–visible absorption spectrum is a convenient technique for detecting chemical changes of proteins, and it is therefore useful to combine spectroscopy and diffraction studies. An online microspectrophotometer for the UV–visible region was developed and installed on the macromolecular crystallography beamline, BL38B1, at SPring-8. This spectrophotometer is equipped with a difference dispersive double monochromator, a mercury–xenon lamp as the light source, and a photomultiplier as the detector. The optical path is mostly constructed using mirrors, in order to obtain high brightness in the UV region, and the confocal optics are assembled using a cross-slit diaphragm like an iris to eliminate stray light. This system can measure optical densities up to a maximum of 4.0. To study the effect of radiation damage, preliminary measurements of glucose isomerase and thaumatin crystals were conducted in the UV region. Spectral changes dependent on X-ray dose were observed at around 280 nm, suggesting that structural changes involving Trp or Tyr residues occurred in the protein crystal. In the case of the thaumatin crystal, a broad peak around 400 nm was also generated after X-ray irradiation, suggesting the cleavage of a disulfide bond. Dose-dependent spectral changes were also observed in cryo-solutions alone, and these changes differed with the composition of the cryo-solution. These responses in the UV region are informative regarding the state of the sample; consequently, this device might be useful for X-ray crystallography.

  7. Electrochromic characteristics of a nickel borate thin film investigated by in situ XAFS and UV/vis spectroscopy

    International Nuclear Information System (INIS)

    Yoshida, Masaaki; Iida, Tsuyoshi; Mineo, Takehiro

    2014-01-01

    The electrochromic transition of a nickel borate thin film between colorless and brown was examined by means of in situ XAFS and UV/vis spectroscopy. The XAFS spectra showed that the average valence state of the nickel species in the film changed from +2.1 to +3.8 following the application of an electrode potential. Additionally, a broad peak at 700 nm was observed during in situ UV/vis absorption measurements on the application of a positive potential. These results suggest that the nickel borate film reversibly forms a NiOOH structure with a domain size of several nanometers during the electrochromic reaction. (author)

  8. Very high resolution UV and x-ray spectroscopy and imagery of solar active regions. Final report

    International Nuclear Information System (INIS)

    Bruner, M.; Brown, W.A.; Haisch, B.M.

    1987-01-01

    A scientific investigation of the physics of the solar atmosphere, which uses the techniques of high resolution soft x-ray spectroscopy and high resolution UV imagery, is described. The experiments were conducted during a series of three sounding rocket flights. All three flights yielded excellent images in the UV range, showing unprecedented spatial resolution. The second flight recorded the x-ray spectrum of a solar flare, and the third that of an active region. A normal incidence multi-layer mirror was used during the third flight to make the first astronomical x-ray observations using this new technique

  9. Exploring Space Weathering on Mercury Using Global UV-VIS Reflectance Spectroscopy

    Science.gov (United States)

    Izenberg, N. R.; Denevi, B. W.

    2018-05-01

    We apply UV analysis methods used on lunar LROC data to Mercury to explore space weathering maturity and possibly evidence of shocked minerals. What says the UV // about shock, maturity // on dear Mercury?

  10. Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses.

    Science.gov (United States)

    Vasconcelos, Maydla Dos Santos; Passos, Wilson Espíndola; Lescanos, Caroline Honaiser; Pires de Oliveira, Ivan; Trindade, Magno Aparecido Gonçalves; Caires, Anderson Rodrigues Lima; Muzzi, Rozanna Marques

    2018-01-01

    The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.). The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB) and ∼90% (RSLB). The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2), about 49%, and the oleic monounsaturated (18  :  1), ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3), ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

  11. Simultaneous Determination of Caffeine and Chlorogenic Acids in Green Coffee by UV/Vis Spectroscopy

    Directory of Open Access Journals (Sweden)

    G. Navarra

    2017-01-01

    Full Text Available A simple method for the simultaneous determination of caffeine and chlorogenic acids content in green coffee was reported. The method was based on the use of UV/Vis absorption. It is relevant that the quantification of both caffeine and chlorogenic acids was performed without their preliminary chemical separation despite their spectral overlap in the range 250–350 nm. Green coffee was extracted with 70% ethanol aqueous solution; then the solution was analyzed by spectroscopy. Quantitative determination was obtained analytically through deconvolution of the absorption spectrum and by applying the Lambert-Beer law. The bands used for the deconvolution were the absorption bands of both caffeine and chlorogenic acids standards. The molar extinction coefficients for caffeine and chlorogenic acid in ethanol solution at 70% were calculated by using the chemical standards; the estimated values were ε(272 nm=12159±97 M−1 cm−1 for caffeine and ε(330 nm=27025±190 M−1 cm−1 for chlorogenic acids molecules, respectively. The estimate of concentration values was in agreement with the one obtained by High Performance Liquid Chromatography quantification. The method is fast and simple and allows us to realize routine controls during the coffee production. In addition, it could be applied on roasted coffee and espresso coffee.

  12. Evaluation of local strain in Si using UV-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ogura, Atsushi [School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan)], E-mail: a_ogura@isc.meiji.ac.jp; Kosemura, Daisuke; Takei, Munehisa [School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Uchida, Hidetsugu; Hattori, Nobuyoshi [Semiconductor Technology Academic Research Center, 3-17-2 Shinyokohama, Kouhoku-ku, Yokohama 220-0033 (Japan); Yoshimaru, Masaki [Semiconductor Business Group, Sony Corporation, Atsugi Tec., 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Mayuzumi, Satoru [School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Semiconductor Business Group, Sony Corporation, Atsugi Tec., 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Wakabayashi, Hitoshi [Semiconductor Business Group, Sony Corporation, Atsugi Tec., 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan)

    2009-03-15

    'Strained-Si', in which intentional strain is introduced in Si crystal to improve carrier mobility by using a modulated band structure, is recognized as one of the most important technologies in post-scaling-generation LSIs. Strain-evaluation technology to probe strain in shallow surfaces that correspond to the channels of MOSFETs is crucial to achieving strained-Si technology. In this paper, we introduce the results we obtained by evaluating strain with the new UV-Raman spectroscopy we developed. Quasi-line shape illumination enabled Raman measurements with 200-nm intervals on the sample. The local-strain mechanism caused by SiN stressors covering a MOSFET was clarified by measuring one-dimensional strain profiles induced by patterned SiN film on Si. We also demonstrated that the induced strain was proportional to the inner stresses of SiN film and that it is more effective to introduce strain in SOI substrates than in bulk substrates. In the evaluation of a actual device fabricated by using the gate-last process in which strain was significantly enhanced after the dummy gate was removed, the size effect, i.e., an increase in induced strain with a decrease in gate length, was confirmed through one-dimensional strain-profile measurements with various gate lengths.

  13. Evaluation of local strain in Si using UV-Raman spectroscopy

    International Nuclear Information System (INIS)

    Ogura, Atsushi; Kosemura, Daisuke; Takei, Munehisa; Uchida, Hidetsugu; Hattori, Nobuyoshi; Yoshimaru, Masaki; Mayuzumi, Satoru; Wakabayashi, Hitoshi

    2009-01-01

    'Strained-Si', in which intentional strain is introduced in Si crystal to improve carrier mobility by using a modulated band structure, is recognized as one of the most important technologies in post-scaling-generation LSIs. Strain-evaluation technology to probe strain in shallow surfaces that correspond to the channels of MOSFETs is crucial to achieving strained-Si technology. In this paper, we introduce the results we obtained by evaluating strain with the new UV-Raman spectroscopy we developed. Quasi-line shape illumination enabled Raman measurements with 200-nm intervals on the sample. The local-strain mechanism caused by SiN stressors covering a MOSFET was clarified by measuring one-dimensional strain profiles induced by patterned SiN film on Si. We also demonstrated that the induced strain was proportional to the inner stresses of SiN film and that it is more effective to introduce strain in SOI substrates than in bulk substrates. In the evaluation of a actual device fabricated by using the gate-last process in which strain was significantly enhanced after the dummy gate was removed, the size effect, i.e., an increase in induced strain with a decrease in gate length, was confirmed through one-dimensional strain-profile measurements with various gate lengths.

  14. Quantitative methods for structural characterization of proteins based on deep UV resonance Raman spectroscopy.

    Science.gov (United States)

    Shashilov, Victor A; Sikirzhytski, Vitali; Popova, Ludmila A; Lednev, Igor K

    2010-09-01

    Here we report on novel quantitative approaches for protein structural characterization using deep UV resonance Raman (DUVRR) spectroscopy. Specifically, we propose a new method combining hydrogen-deuterium (HD) exchange and Bayesian source separation for extracting the DUVRR signatures of various structural elements of aggregated proteins including the cross-beta core and unordered parts of amyloid fibrils. The proposed method is demonstrated using the set of DUVRR spectra of hen egg white lysozyme acquired at various stages of HD exchange. Prior information about the concentration matrix and the spectral features of the individual components was incorporated into the Bayesian equation to eliminate the ill-conditioning of the problem caused by 100% correlation of the concentration profiles of protonated and deuterated species. Secondary structure fractions obtained by partial least squares (PLS) and least squares support vector machines (LS-SVMs) were used as the initial guess for the Bayessian source separation. Advantages of the PLS and LS-SVMs methods over the classical least squares calibration (CLSC) are discussed and illustrated using the DUVRR data of the prion protein in its native and aggregated forms. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  15. Thermal edible oil evaluation by UV-Vis spectroscopy and chemometrics.

    Science.gov (United States)

    Gonçalves, Rhayanna P; Março, Paulo H; Valderrama, Patrícia

    2014-11-15

    Edible oils such as colza, corn, sunflower, soybean and olive were analysed by UV-Vis spectroscopy and Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS). When vegetable oils were heated at high temperatures (frying), oxidation products were formed which were harmful to human health in addition to degrading the antioxidants present, and this study aimed to evaluate tocopherol (one antioxidant present in oils) and the behaviour of oxidation products in edible oils. The MCR-ALS results showed that the degradation started at 110°C and 85°C, respectively, for sunflower and colza oils, while tocopherol concentration decreased and oxidation products increased starting at 70°C in olive oil. In soybean and corn oils, tocopherol concentration started to decrease and oxidation products increased at 50°C. The results suggested that sunflower, colza and olive oils offered more resistance to increasing temperatures, while soybean and corn oils were less resistant. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Investigation of the hydrated 7-hydroxy-4-methylcoumarin dimer by combined IR/UV spectroscopy

    International Nuclear Information System (INIS)

    Stamm, A.; Schwing, K.; Gerhards, M.

    2014-01-01

    The first molecular beam investigations on a coumarin dimer and clusters of a coumarin dimer with water both in the neutral (S 0 ) and cationic (D 0 ) electronic ground state are performed. The structure and structural changes due to ionization of the isolated 7-hydroxy-4-methylcoumarin dimer (7H4MC) 2 as well as its mono- and dihydrate (7H4MC) 2 (H 2 O) 1-2 are analyzed by applying combined IR/UV spectroscopy compared with density functional theory calculations. In case of the neutral dimer of 7H4MC a doubly hydrogen-bonded structure is formed. This doubly hydrogen-bonded arrangement opens to a singly hydrogen-bonded structure in the ion presenting a rearrangement reaction within an isolated dimer. By attaching one or two water molecules to the neutral 7H4MC dimer water is inserted into the hydrogen bonds. In contrast to the non-hydrated species this general binding motif with water in a bridging function does not change via ionization but especially for the dihydrate the spatial arrangement of the two 7H4MC units changes strengthening the interaction between the aromatic chromophores. The presented analyses illustrate the strong dependence of binding motifs as a function of successive hydration and charge including a rearrangement reaction

  17. UV-VIS Spectroscopy Applied to Stratospheric Chemistry, Methods and Results

    Energy Technology Data Exchange (ETDEWEB)

    Karlsen, K.

    1996-03-01

    This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. Numerous observations and modeling have shown with a very high degree of certainty that the man-made emissions of chlorofluorocarbons (CFC) and halons are responsible for the Antarctica ozone hole. It is also evident that the ozone layer of the Northern Hemisphere has suffered a certain decline over the last 10-15 years, possibly because of CFC and halons. 20-30% of the observed reduction is ascribed to coupled chlorine and bromine chemistry via a catalytic cycle resulting in the net conversion of 2O{sub 3} to 3O{sub 2}. But the details are not fully understood. The author plans to assemble a UV-VIS spectrometer for measuring the species OClO and BrO and to compare and discuss measured diurnal variations of OClO and BrO with model calculations. The use of Differential Optical Absorption Spectroscopy (DOAS) is discussed and some results from late 1995 presented. 6 refs., 2 figs.

  18. Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses

    Directory of Open Access Journals (Sweden)

    Maydla dos Santos Vasconcelos

    2018-01-01

    Full Text Available The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.. The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB and ∼90% (RSLB. The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2, about 49%, and the oleic monounsaturated (18  :  1, ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3, ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

  19. New Atomic Data for Doubly Ionized Iron Group Atoms by High Resolution UV Fourier Transform Spectroscopy

    Science.gov (United States)

    Smith, Peter L.; Pickering, Juliet C.; Thorne, A. P.

    2002-01-01

    Currently available laboratory spectroscopic data of doubly ionized iron-group element were obtained about 50 years ago using spectrographs of modest dispersion, photographic plates, and eye estimates of intensities. The accuracy of the older wavelength data is about 10 mAngstroms at best, whereas wavelengths are now needed to an accuracy of 1 part in 10(exp 6) to 10(exp 7) (0.2 to 2 mAngstroms at 2000 Angstroms). The Fourier transform (FT) spectroscopy group at Imperial College, London, and collaborators at the Harvard College Observatory have used a unique VUV FT spectrometer in a program focussed on improving knowledge of spectra of many neutral and singly and doubly ionized, astrophysically important, iron group elements. Spectra of Fe II and Fe III have been recorded at UV and VUV wavelengths with signal-to-noise ratios of several hundred for the stronger lines. Wavelengths and energy levels for Fe III are an order of magnitude more accurate than previous work; analysis is close to completion. f-values for Fe II have been published.

  20. Gaz Phase IR and UV Spectroscopy of Neutral Contact Ion Pairs

    Science.gov (United States)

    Habka, Sana; Brenner, Valerie; Mons, Michel; Gloaguen, Eric

    2016-06-01

    Cations and anions, in solution, tend to pair up forming ion pairs. They play a crucial role in many fundamental processes in ion-concentrated solutions and living organisms. Despite their importance and vast applications in physics, chemistry and biochemistry, they remain difficult to characterize namely because of the coexistence of several types of pairing in solution. However, an interesting alternative consists in applying highly selective gas phase spectroscopy which can offer new insights on these neutral ion pairs. Our study consists in characterizing contact ion pairs (CIPs) in isolated model systems (M+, Ph-(CH2)n-COO- with M=Li, Na, K, Rb, Cs, and n=1-3), to determine their spectral signatures and compare them to ion pairs in solution. We have used laser desorption to vaporize a solid tablet containing the desired salt. Structural information for each system was obtained by mass-selective, UV and IR laser spectroscopy combined with high level quantum chemistry calculations1. Evidence of the presence of neutral CIPs was found by scanning the π-π* transition of the phenyl ring using resonant two-photon ionization (R2PI). Then, conformational selective IR/UV double resonance spectra were recorded in the CO2- stretch region for each conformation detected. The good agreement between theoretical data obtained at the BSSE-corrected-fullCCSD(T)/dhf-TZVPP//B97-D3/dhf-TZVPP level and experimental IR spectra led us to assign the 3D structure for each ion pair formed. Spectral signatures of (M+, Ph-CH2-COO-) pairs, were assigned to a bidentate CIPs between the alkali cation and the carboxylate group. In the case of (Li+, Ph-(CH2)3-COO-) pairs, the presence of a flexible side chain promotes a cation-π interaction leading to a tridentate O-O-π structure with its unique IR and UV signatures. IR spectra obtained on isolated CIPs were found very much alike the ones published on lithium and sodium acetate in solution2. However, in the case of sodium acetate, solution

  1. Extending differential optical absorption spectroscopy for limb measurements in the UV

    Directory of Open Access Journals (Sweden)

    J. Puķīte

    2010-05-01

    Full Text Available Methods of UV/VIS absorption spectroscopy to determine the constituents in the Earth's atmosphere from measurements of scattered light are often based on the Beer-Lambert law, like e.g. Differential Optical Absorption Spectroscopy (DOAS. While the Beer-Lambert law is strictly valid for a single light path only, the relation between the optical depth and the concentration of any absorber can be approximated as linear also for scattered light observations at a single wavelength if the absorption is weak. If the light path distribution is approximated not to vary with wavelength, also linearity between the optical depth and the product of the cross-section and the concentration of an absorber can be assumed. These assumptions are widely made for DOAS applications for scattered light observations.

    For medium and strong absorption of scattered light (e.g. along very long light-paths like in limb geometry the relation between the optical depth and the concentration of an absorber is no longer linear. In addition, for broad wavelength intervals the differences in the travelled light-paths at different wavelengths become important, especially in the UV, where the probability for scattering increases strongly with decreasing wavelength.

    However, the DOAS method can be extended to cases with medium to strong absorptions and for broader wavelength intervals by the so called air mass factor modified (or extended DOAS and the weighting function modified DOAS. These approaches take into account the wavelength dependency of the slant column densities (SCDs, but also require a priori knowledge for the air mass factor or the weighting function from radiative transfer modelling.

    We describe an approach that considers the fitting results obtained from DOAS, the SCDs, as a function of wavelength and vertical optical depth and expands this function into a Taylor series of both quantities. The Taylor coefficients are then applied as

  2. Using resonance light scattering and UV/vis absorption spectroscopy to study the interaction between gliclazide and bovine serum albumin.

    Science.gov (United States)

    Zhang, Qiu-Ju; Liu, Bao-Sheng; Li, Gai-Xia; Han, Rong

    2016-08-01

    At different temperatures (298, 310 and 318 K), the interaction between gliclazide and bovine serum albumin (BSA) was investigated using fluorescence quenching spectroscopy, resonance light scattering spectroscopy and UV/vis absorption spectroscopy. The first method studied changes in the fluorescence of BSA on addition of gliclazide, and the latter two methods studied the spectral change in gliclazide while BSA was being added. The results indicated that the quenching mechanism between BSA and gliclazide was static. The binding constant (Ka ), number of binding sites (n), thermodynamic parameters, binding forces and Hill's coefficient were calculated at three temperatures. Values for the binding constant obtained using resonance light scattering and UV/vis absorption spectroscopy were much greater than those obtained from fluorescence quenching spectroscopy, indicating that methods monitoring gliclazide were more accurate and reasonable. In addition, the results suggest that other residues are involved in the reaction and the mode 'point to surface' existed in the interaction between BSA and gliclazide. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  3. Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy.

    Science.gov (United States)

    Kozik, Violetta; Jarzembek, Krystyna; Jędrzejowska, Agnieszka; Bąk, Andrzej; Polak, Justyna; Bartoszek, Mariola; Pytlakowska, Katarzyna

    2015-01-01

    Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r)=0.90 and determination coefficient (r2)=0.81 (P<0.05).

  4. Crystallography and Drug Design

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 12. Crystallography and Drug Design. K Suguna. General Article Volume 19 Issue 12 December 2014 pp 1093-1103. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/019/12/1093-1103. Keywords.

  5. High-pressure crystallography

    Science.gov (United States)

    Katrusiak, A.

    2008-01-01

    The history and development of high-pressure crystallography are briefly described and examples of structural transformations in compressed compounds are given. The review is focused on the diamond-anvil cell, celebrating its 50th anniversary this year, the principles of its operation and the impact it has had on high-pressure X-ray diffraction.

  6. The Structure of p-Aminobenzoic Acid in Water: Studies Combining UV-Vis, NEXAFS and RIXS Spectroscopies

    International Nuclear Information System (INIS)

    Gainar, A; Stevens, J S; Schroeder, S L M; Suljoti, E; Xiao, J; Golnak, R; Aziz, E F

    2016-01-01

    NEXAFS-RIXS and home laboratory-based UV-Vis absorption spectroscopy are combined to examine the speciation and electronic structure of para -aminobenzoic acid (PABA) in aqueous solution as a function of pH. DFT and TD-DFT electronic structure calculations reproduce the experimental trends and provide a correlation between the experimental HOMO↔LUMO gap as well as the electronic transitions between molecular orbitals in the non-ionic, anionic and cationic forms of PABA. (paper)

  7. Monitoring ultraviolet (UV) radiation inactivation of Cronobacter sakazakii in dry infant formula using Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Liu, Qian; Lu, Xiaonan; Swanson, Barry G; Rasco, Barbara A; Kang, Dong-Hyun

    2012-01-01

    Cronobacter sakazakii is an opportunistic pathogen associated with dry infant formula presenting a high risk to low birth weight neonates. The inactivation of C. sakazakii in dry infant formula by ultraviolet (UV) radiation alone and combined with hot water treatment at temperatures of 55, 60, and 65 °C were applied in this study. UV radiation with doses in a range from 12.1 ± 0.30 kJ/m² to 72.8 ± 1.83 kJ/m² at room temperature demonstrated significant inactivation of C. sakazakii in dry infant formula (P radiation combining 60 °C hot water treatment increased inactivation of C. sakazakii cells significantly (P radiation on C. sakazakii inactivation kinetics (D value) were not observed in infant formula reconstituted in 55 and 65 °C water (P > 0.05). The inactivation mechanism was investigated using vibrational spectroscopy. Infrared spectroscopy detected significant stretching mode changes of macromolecules on the basis of spectral features, such as DNA, proteins, and lipids. Minor changes on cell membrane composition of C. sakazakii under UV radiation could be accurately and correctly monitored by infrared spectroscopy coupled with 2nd derivative transformation and principal component analysis. © 2011 Institute of Food Technologists®

  8. Experimental conditions affecting the kinetics of aqueous HCN polymerization as revealed by UV-vis spectroscopy.

    Science.gov (United States)

    Marín-Yaseli, Margarita R; Moreno, Miguel; de la Fuente, José L; Briones, Carlos; Ruiz-Bermejo, Marta

    2018-02-15

    HCN polymerization is one of the most important and fascinating reactions in prebiotic chemistry, and interest in HCN polymers in the field of materials science is growing. However, little is known about the kinetics of the HCN polymerization process. In the present study, a first approach to the kinetics of two sets of aqueous HCN polymerizations, from NH 4 CN and NaCN, at middle temperatures between 4 and 38°C, has been carried out. For each series, the presence of air and salts in the reaction medium has been systematically explored. A previous kinetic analysis was conducted during the conversion of the insoluble black HCN polymers obtained as gel fractions in these precipitation polymerizations for a reaction of one month, where a limit conversion was achieved at the highest polymerization temperature. The kinetic description of the gravimetric data for this complex system shows a clear change in the linear dependence with the polymerization temperature for the reaction from NH 4 CN, besides a relevant catalytic effect of ammonium, in comparison with those data obtained from the NaCN series. These results also demonstrated the notable influence of air, oxygen, and the saline medium in HCN polymer formation. Similar conclusions were reached when the sol fractions were monitored by UV-vis spectroscopy, and a Hill type correlation was used to describe the polymerization profiles obtained. This technique was chosen because it provides an easy, prompt and fast method to follow the evolution of the liquid or continuous phase of the process under study. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Insights into the early dissolution events of amlodipine using UV imaging and Raman spectroscopy

    DEFF Research Database (Denmark)

    Boetker, Johan P; Savolainen, Marja; Koradia, Vishal

    2011-01-01

    Traditional dissolution testing determines drug release to the bulk, but does not enable an understanding of the events happening close to the surface of a solid or a tablet. UV imaging is a new imaging approach that can be used to study the dissolution behavior of chemical compounds. The UV imag...

  10. New insight in the template decomposition process of large zeolite ZSM-5 crystals: an in situ UV-Vis/fluorescence micro-spectroscopy study

    NARCIS (Netherlands)

    Karwacki, L.|info:eu-repo/dai/nl/304824283; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2011-01-01

    A combination of in situ UV-Vis and confocal fluorescence micro-spectroscopy was used to study the template decomposition process in large zeolite ZSM-5 crystals. Correlation of polarized light dependent UV-Vis absorption spectra with confocal fluorescence emission spectra in the 400–750 nm region

  11. Quantum crystallography: A perspective.

    Science.gov (United States)

    Massa, Lou; Matta, Chérif F

    2018-06-30

    Extraction of the complete quantum mechanics from X-ray scattering data is the ultimate goal of quantum crystallography. This article delivers a perspective for that possibility. It is desirable to have a method for the conversion of X-ray diffraction data into an electron density that reflects the antisymmetry of an N-electron wave function. A formalism for this was developed early on for the determination of a constrained idempotent one-body density matrix. The formalism ensures pure-state N-representability in the single determinant sense. Applications to crystals show that quantum mechanical density matrices of large molecules can be extracted from X-ray scattering data by implementing a fragmentation method termed the kernel energy method (KEM). It is shown how KEM can be used within the context of quantum crystallography to derive quantum mechanical properties of biological molecules (with low data-to-parameters ratio). © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  12. Racemic protein crystallography.

    Science.gov (United States)

    Yeates, Todd O; Kent, Stephen B H

    2012-01-01

    Although natural proteins are chiral and are all of one "handedness," their mirror image forms can be prepared by chemical synthesis. This opens up new opportunities for protein crystallography. A racemic mixture of the enantiomeric forms of a protein molecule can crystallize in ways that natural proteins cannot. Recent experimental data support a theoretical prediction that this should make racemic protein mixtures highly amenable to crystallization. Crystals obtained from racemic mixtures also offer advantages in structure determination strategies. The relevance of these potential advantages is heightened by advances in synthetic methods, which are extending the size limit for proteins that can be prepared by chemical synthesis. Recent ideas and results in the area of racemic protein crystallography are reviewed.

  13. Crystallography and environment development

    International Nuclear Information System (INIS)

    Radwan, M.M.

    1992-01-01

    Crystallography, the study of atomic and molecular structure, has given detailed information about the fine-structure of the inorganic and living world-i.e. about the environment (in the widest sense of the world)-. It has contributed to geology (at the atomic level), crystal chemistry, the structure of minerals, soils and clays. In the case of the living world it has contributed to structural studies of biological molecules; proteins, nucleic acids (DNA and RNA), and polysaccharides. knowing how the atoms in a material are arranged allows to understand the relationship between atomic structure and properties of these materials. Today we are entering a new age in crystallography-the age of genetic engineering in the living world, and inorganic crystallographic engineering, where we use crystallographic information from the structures nature has given us, to begin to design and build structure of our own, of specified properties, aiming at the welfare of man and the development of his environment

  14. Serial Femtosecond Crystallography

    OpenAIRE

    Chapman, Henry N.

    2015-01-01

    X-ray free-electron lasers produce brief flashes of X-rays that are of about a billion times higher peak brightness than achievable from storage ring sources. Such a tremendous jump in X-ray source capabilities, which came in 2009 when the Linac Coherent Light Source began operations, was unprecedented in the history of X-ray science. Protein structure determination through the method of macromolecular crystallography has consistently benefited from the many increases in source performance fr...

  15. Study of tryptophan assisted synthesis of gold nanoparticles by combining UV-Vis, fluorescence, and SERS spectroscopy

    International Nuclear Information System (INIS)

    Iosin, Monica; Baldeck, Patrice; Astilean, Simion

    2010-01-01

    We developed a rapid and non-toxic method for the preparation of colloidal gold nanoparticles (GNPs) by using tryptophan (Trp) as reducing/stabilizing agent. We show that the temperature has a major influence on the kinetics of gold ion reduction and the crystal growth, higher temperatures favoring the synthesis of anisotropic nanoparticles (triangles and hexagons). The as-synthesized nanostructures were characterized by UV-Vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), fluorescence, and surface-enhanced Raman scattering (SERS) spectroscopy. The UV-Vis measurements confirmed that temperature is a critical factor in the synthesis process, having a major effect on the shape of the synthesized GNPs. Moreover, fluorescence spectroscopy was able to monitor the quenching of the Trp fluorescence during the in situ synthesis of GNPs. Using Trp as molecular analyte to evaluate the SERS efficiency of as-prepared GNPs at different temperatures, we demonstrated that the Raman enhancement of the synthesized gold nanoplates is higher than that of the gold spherical nanoparticles.

  16. Kinetics of the reaction F+NO+M->FNO+M studied by pulse radiolysis combined with time-resolved IR and UV spectroscopy

    DEFF Research Database (Denmark)

    Pagsberg, Palle Bjørn; Sillesen, A.; Jodkowski, J.T.

    1996-01-01

    The title reaction was initiated by pulse radiolysis of SF6/NO gas mixtures, and the formation of FNO was studied by time-resolved IR and UV spectroscopy. At SF6 pressures of 10-320 mbar at 298 K, the formation of FNO was studied by infrared diode laser spectroscopy at 1857.324 cm(-1). Comparative...

  17. Halide ions complex and deprotonate dipicolinamides and isophthalamides: assessment by mass spectrometry and UV-visible spectroscopy.

    Science.gov (United States)

    Carasel, I Alexandru; Yamnitz, Carl R; Winter, Rudolph K; Gokel, George W

    2010-12-03

    The F(-), Cl(-), and Br(-) binding selectivity of bis(p-nitroanilide)s of dipicolinic and isophthalic acids was studied by using competitive electrospray mass spectrometry and UV-Visible spectroscopy. Both hosts prefer binding Cl(-) over either F(-) or Br(-). Host deprotonation was observed to some extent in all experiments in which the host was exposed to halide ions. When F(-) was present, host deprotonation was often the major process, whereas little deprotonation was observed by Cl(-) or Br(-), which preferred complexation. A solution of either host changed color when mixed with a F(-), H(2)PO(4)(-), di- or triphenylacetate solution.

  18. The story of crystallography

    International Nuclear Information System (INIS)

    Nigam, G.D.

    1976-01-01

    The historical development of the very important field of crystallography has been narrated. The important land marks such as the first determination of the crystal structure of NaCl by Sir Poragy and that of DNA by Watson et al., etc. are mentioned. The important role played by this field and its role in bringing broad fields such as physics, chemistry and biology very close to each other are emphasised. Some of the outstanding contributions made by eminent crystallographers in India and abroad are mentioned. (K.B.)

  19. A new approach for heparin standardization: combination of scanning UV spectroscopy, nuclear magnetic resonance and principal component analysis.

    Directory of Open Access Journals (Sweden)

    Marcelo A Lima

    Full Text Available The year 2007 was marked by widespread adverse clinical responses to heparin use, leading to a global recall of potentially affected heparin batches in 2008. Several analytical methods have since been developed to detect impurities in heparin preparations; however, many are costly and dependent on instrumentation with only limited accessibility. A method based on a simple UV-scanning assay, combined with principal component analysis (PCA, was developed to detect impurities, such as glycosaminoglycans, other complex polysaccharides and aromatic compounds, in heparin preparations. Results were confirmed by NMR spectroscopy. This approach provides an additional, sensitive tool to determine heparin purity and safety, even when NMR spectroscopy failed, requiring only standard laboratory equipment and computing facilities.

  20. Photoelectron and UV absorption spectroscopy for determination of electronic configurations of negative molecular ions: Chlorophenols

    International Nuclear Information System (INIS)

    Tseplin, E.E.; Tseplina, S.N.; Tuimedov, G.M.; Khvostenko, O.G.

    2009-01-01

    The photoelectron and UV absorption spectra of p-, m-, and o-chlorophenols in the gas phase have been obtained. On the basis of DFT B3LYP/6-311++G(d, p) calculations, the photoelectron bands have been assigned to occupied molecular orbitals. From the TDDFT B3LYP/6-311++G(d, p) calculation results, the UV absorption bands have been assigned to excited singlet states of the molecules under investigation. For each excited state a dominant transition was found. It has been shown that the energies of these singlet transitions correlate with the energy differences between the ground-state molecular orbitals participating in them. Using the UV spectra interpretation, the electronic states of molecular anions detected earlier for the same compounds by means of the resonant electron capture mass-spectrometry have been determined.

  1. Teaching UV-Vis Spectroscopy with a 3D-Printable Smartphone Spectrophotometer

    Science.gov (United States)

    Grasse, Elise K.; Torcasio, Morgan H.; Smith, Adam W.

    2016-01-01

    Visible absorbance spectroscopy is a widely used tool in chemical, biochemical, and medical laboratories. The theory and methods of absorbance spectroscopy are typically introduced in upper division undergraduate chemistry courses, but could be introduced earlier with the right curriculum and instrumentation. A major challenge in teaching…

  2. Combining EPR spectroscopy and X-ray crystallography to elucidate the structure and dynamics of conformationally constrained spin labels in T4 lysozyme single crystals.

    Science.gov (United States)

    Consentius, Philipp; Gohlke, Ulrich; Loll, Bernhard; Alings, Claudia; Heinemann, Udo; Wahl, Markus C; Risse, Thomas

    2017-08-09

    Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling is used to investigate the structure and dynamics of conformationally constrained spin labels in T4 lysozyme single crystals. Within a single crystal, the oriented ensemble of spin bearing moieties results in a strong angle dependence of the EPR spectra. A quantitative description of the EPR spectra requires the determination of the unit cell orientation with respect to the sample tube and the orientation of the spin bearing moieties within the crystal lattice. Angle dependent EPR spectra were analyzed by line shape simulations using the stochastic Liouville equation approach developed by Freed and co-workers and an effective Hamiltonian approach. The gain in spectral information obtained from the EPR spectra of single crystalline samples taken at different frequencies, namely the X-band and Q-band, allows us to discriminate between motional models describing the spectra of isotropic solutions similarly well. In addition, it is shown that the angle dependent single crystal spectra allow us to identify two spin label rotamers with very similar side chain dynamics. These results demonstrate the utility of single crystal EPR spectroscopy in combination with spectral line shape simulation techniques to extract valuable dynamic information not readily available from the analysis of isotropic systems. In addition, it will be shown that the loss of electron density in high resolution diffraction experiments at room temperature does not allow us to conclude that there is significant structural disorder in the system.

  3. Geographic identification of Boletus mushrooms by data fusion of FT-IR and UV spectroscopies combined with multivariate statistical analysis

    Science.gov (United States)

    Yao, Sen; Li, Tao; Li, JieQing; Liu, HongGao; Wang, YuanZhong

    2018-06-01

    Boletus griseus and Boletus edulis are two well-known wild-grown edible mushrooms which have high nutrition, delicious flavor and high economic value distributing in Yunnan Province. In this study, a rapid method using Fourier transform infrared (FT-IR) and ultraviolet (UV) spectroscopies coupled with data fusion was established for the discrimination of Boletus mushrooms from seven different geographical origins with pattern recognition method. Initially, the spectra of 332 mushroom samples obtained from the two spectroscopic techniques were analyzed individually and then the classification performance based on data fusion strategy was investigated. Meanwhile, the latent variables (LVs) of FT-IR and UV spectra were extracted by partial least square discriminant analysis (PLS-DA) and two datasets were concatenated into a new matrix for data fusion. Then, the fusion matrix was further analyzed by support vector machine (SVM). Compared with single spectroscopic technique, data fusion strategy can improve the classification performance effectively. In particular, the accuracy of correct classification of SVM model in training and test sets were 99.10% and 100.00%, respectively. The results demonstrated that data fusion of FT-IR and UV spectra can provide higher synergic effect for the discrimination of different geographical origins of Boletus mushrooms, which may be benefit for further authentication and quality assessment of edible mushrooms.

  4. In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV-visible spectroscopy.

    Science.gov (United States)

    Alin, Jonas; Rubino, Maria; Auras, Rafael

    2015-10-15

    UV-visible (UV-Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay's behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay's behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV-Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter.

    Science.gov (United States)

    Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

    2018-05-05

    The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C 10 mimBF 4 , C 12 mimBF 4 , C 16 mimBF 4 ) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C 16 mimBF 4 >CTAB>C 12 mimBF 4 >C 10 mimBF 4 . Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1 H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter

    Science.gov (United States)

    Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

    2018-05-01

    The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C10mimBF4, C12mimBF4, C16mimBF4) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C16mimBF4 > CTAB > C12mimBF4 > C10mimBF4. Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes.

  7. A modern approach to the authentication and quality assessment of thyme using UV spectroscopy and chemometric analysis.

    Science.gov (United States)

    Gad, Haidy A; El-Ahmady, Sherweit H; Abou-Shoer, Mohamed I; Al-Azizi, Mohamed M

    2013-01-01

    Recently, the fields of chemometrics and multivariate analysis have been widely implemented in the quality control of herbal drugs to produce precise results, which is crucial in the field of medicine. Thyme represents an essential medicinal herb that is constantly adulterated due to its resemblance to many other plants with similar organoleptic properties. To establish a simple model for the quality assessment of Thymus species using UV spectroscopy together with known chemometric techniques. The success of this model may also serve as a technique for the quality control of other herbal drugs. The model was constructed using 30 samples of authenticated Thymus vulgaris and challenged with 20 samples of different botanical origins. The methanolic extracts of all samples were assessed using UV spectroscopy together with chemometric techniques: principal component analysis (PCA), soft independent modeling of class analogy (SIMCA) and hierarchical cluster analysis (HCA). The model was able to discriminate T. vulgaris from other Thymus, Satureja, Origanum, Plectranthus and Eriocephalus species, all traded in the Egyptian market as different types of thyme. The model was also able to classify closely related species in clusters using PCA and HCA. The model was finally used to classify 12 commercial thyme varieties into clusters of species incorporated in the model as thyme or non-thyme. The model constructed is highly recommended as a simple and efficient method for distinguishing T. vulgaris from other related species as well as the classification of marketed herbs as thyme or non-thyme. Copyright © 2013 John Wiley & Sons, Ltd.

  8. Characterization of dissolved organic matter in Dongjianghu Lake by UV-visible absorption spectroscopy with multivariate analysis.

    Science.gov (United States)

    Zhu, Yanzhong; Song, Yonghui; Yu, Huibin; Liu, Ruixia; Liu, Lusan; Lv, Chunjian

    2017-08-08

    UV-visible absorption spectroscopy coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to characterize spectroscopic components, detect latent factors, and investigate spatial variations of dissolved organic matter (DOM) in a large-scale lake. Twelve surface water samples were collected from Dongjianghu Lake in China. DOM contained lignin and quinine moieties, carboxylic acid, microbial products, and aromatic and alkyl groups, which in the northern part of the lake was largely different from the southern part. Fifteen spectroscopic indices were deduced from the absorption spectra to indicate molecular weight or humification degree of DOM. The northern part of the lake presented the smaller molecular weight or the lower humification degree of DOM than the southern part. E 2/4 , E 3/4 , E 2/3 , and S 2 were latent factors of characterizing the molecular weight of DOM, while E 2/5 , E 3/5 , E 2/6 , E 4/5 , E 3/6 , and A 2/1 were latent factors of evaluating the humification degree of DOM. The UV-visible absorption spectroscopy combined with PCA and HCA may not only characterize DOM fractions of lakes, but may be transferred to other types of waterscape.

  9. Growth of block copolymer stabilized metal nanoparticles probed simultaneously by in situ XAS and UV-Vis spectroscopy.

    Science.gov (United States)

    Nayak, C; Bhattacharyya, D; Jha, S N; Sahoo, N K

    2016-01-01

    The growth of Au and Pt nanoparticles from their respective chloride precursors using block copolymer-based reducers has been studied by simultaneous in situ measurement of XAS and UV-Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at INDUS-2 SRS at RRCAT, Indore, India. While the XANES spectra of the precursor give real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed at the intermediate stages of growth. The growth kinetics of both types of nanoparticles are found to be almost similar and are found to follow three stages, though the first stage of nucleation takes place earlier in the case of Au than in the case of Pt nanoparticles due to the difference in the reduction potential of the respective precursors. The first two stages of the growth of Au and Pt nanoparticles as obtained by in situ XAS measurements could be corroborated by simultaneous in situ measurement of UV-Vis spectroscopy also.

  10. Monitoring light-induced structural changes of Channelrhodopsin-2 by UV-visible and Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Ritter, Eglof; Stehfest, Katja; Berndt, Andre; Hegemann, Peter; Bartl, Franz J

    2008-12-12

    Channelrhodopsin-2 (ChR2) is a microbial type rhodopsin and a light-gated cation channel that controls phototaxis in Chlamydomonas. We expressed ChR2 in COS-cells, purified it, and subsequently investigated this unusual photoreceptor by flash photolysis and UV-visible and Fourier transform infrared difference spectroscopy. Several transient photoproducts of the wild type ChR2 were identified, and their kinetics and molecular properties were compared with those of the ChR2 mutant E90Q. Based on the spectroscopic data we developed a model of the photocycle comprising six distinguishable intermediates. This photocycle shows similarities to the photocycle of the ChR2-related Channelrhodopsin of Volvox but also displays significant differences. We show that molecular changes include retinal isomerization, changes in hydrogen bonding of carboxylic acids, and large alterations of the protein backbone structure. These alterations are stronger than those observed in the photocycle of other microbial rhodopsins like bacteriorhodopsin and are related to those occurring in animal rhodopsins. UV-visible and Fourier transform infrared difference spectroscopy revealed two late intermediates with different time constants of tau = 6 and 40 s that exist during the recovery of the dark state. The carboxylic side chain of Glu(90) is involved in the slow transition. The molecular changes during the ChR2 photocycle are discussed with respect to other members of the rhodopsin family.

  11. Study of Polymer Material Aging by Laser Mass Spectrometry, UV-Visible Spectroscopy, and Environmental Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Junien Exposito

    2007-01-01

    Full Text Available Dyed natural rubber (NR and styrene butadiene rubber (SBR, designed for outdoor applications, were exposed to an accelerated artificial aging in xenon light. The aging results in the deterioration of the exposed surface material properties. The ability of dyed polymers to withstand prolonged sunlight exposure without fading or undergoing any physical deterioration is largely determined not only by the photochemical characteristics of the absorbing dyestuff itself but also by the polymer structure and fillers. Results obtained by laser mass spectrometry, UV-visible spectroscopy, and environmental scanning electron microscopy indicate that dyed filled NR and SBR samples behave differently during the photo-oxidation. The fading of the dyed polymers was found to be promoted in the NR sample. This can be correlated with LDI-FTICRMS results, which show the absence of [M-H]− orange pigment pseudomolecular ion and also its fragment ions after aging. This is confirmed by both EDX and UV/Vis spectroscopy. EDX analysis indicates a concentration of chlorine atoms, which can be considered as a marker of orange pigment or its degradation products, only at the surface of SBR flooring after aging. Reactivity of radicals formed during flooring aging has been studied and seems to greatly affect the behavior of such organic pigments.

  12. Single-photon cesium Rydberg excitation spectroscopy using 318.6-nm UV laser and room-temperature vapor cell.

    Science.gov (United States)

    Wang, Jieying; Bai, Jiandong; He, Jun; Wang, Junmin

    2017-09-18

    We demonstrate a single-photon Rydberg excitation spectroscopy of cesium (Cs) atoms in a room-temperature vapor cell. Cs atoms are excited directly from 6S 1/2 ground state to nP 3/2 (n = 70 - 100) Rydberg states with a 318.6 nm ultraviolet (UV) laser, and Rydberg excitation spectra are obtained by transmission enhancement of a probe beam resonant to Cs 6S 1/2 , F = 4 - 6P 3/2 , F' = 5 transition as partial population on F = 4 ground state are transferred to Rydberg state. Analysis reveals that the observed spectra are velocity-selective spectroscopy of Rydberg state, from which the amplitude and linewidth influenced by lasers' Rabi frequency have been investigated. Fitting to energies of Cs nP 3/2 (n = 70 -100) states, the determined quantum defect is 3.56671(42). The demodulated spectra can also be employed as frequency references to stabilize the UV laser frequency to specific Cs Rydberg transition.

  13. Instrumental Analysis in the High School Classroom: UV-Vis Spectroscopy

    Science.gov (United States)

    Erhardt, Walt

    2007-01-01

    Note is presented on the standard lab from a second year chemistry course. The lab "Determining which of the Seven FD&C Food-Approved Dyes are Used in Making Green Skittles", familiarizes students with the operation of the CHEM2000 UV-Vis spectrophorometer.

  14. Vibrationally resolved UV/Vis spectroscopy with time-dependent density functional based tight binding

    NARCIS (Netherlands)

    Ruger, R.; Niehaus, T.; van Lenthe, E.; Heine, T.; Visscher, L.

    2016-01-01

    We report a time-dependent density functional based tight-binding (TD-DFTB) scheme for the calculation of UV/Vis spectra, explicitly taking into account the excitation of nuclear vibrations via the adiabatic Hessian Franck-Condon method with a harmonic approximation for the nu- clear wavefunction.

  15. Quantification of Coffea arabica and Coffea canephora var. robusta concentration in blends by means of synchronous fluorescence and UV-Vis spectroscopies.

    Science.gov (United States)

    Dankowska, A; Domagała, A; Kowalewski, W

    2017-09-01

    The potential of fluorescence, UV-Vis spectroscopies as well as the low- and mid-level data fusion of both spectroscopies for the quantification of concentrations of roasted Coffea arabica and Coffea canephora var. robusta in coffee blends was investigated. Principal component analysis was used to reduce data multidimensionality. To calculate the level of undeclared addition, multiple linear regression (PCA-MLR) models were used with lowest root mean square error of calibration (RMSEC) of 3.6% and root mean square error of cross-validation (RMSECV) of 7.9%. LDA analysis was applied to fluorescence intensities and UV spectra of Coffea arabica, canephora samples, and their mixtures in order to examine classification ability. The best performance of PCA-LDA analysis was observed for data fusion of UV and fluorescence intensity measurements at wavelength interval of 60nm. LDA showed that data fusion can achieve over 96% of correct classifications (sensitivity) in the test set and 100% of correct classifications in the training set, with low-level data fusion. The corresponding results for individual spectroscopies ranged from 90% (UV-Vis spectroscopy) to 77% (synchronous fluorescence) in the test set, and from 93% to 97% in the training set. The results demonstrate that fluorescence, UV, and visible spectroscopies complement each other, giving a complementary effect for the quantification of roasted Coffea arabica and Coffea canephora var. robusta concentration in blends. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Chemical behavior of methylpyranomalvidin-3-O-glucoside in aqueous solution studied by NMR and UV-visible spectroscopy.

    Science.gov (United States)

    Oliveira, Joana; Petrov, Vesselin; Parola, A Jorge; Pina, Fernando; Azevedo, Joana; Teixeira, Natércia; Brás, Natércia F; Fernandes, Pedro A; Mateus, Nuno; Ramos, Maria João; de Freitas, Victor

    2011-02-17

    In the present work, the proton-transfer reactions of the methylpyranomalvidin-3-O-glucoside pigment in water with different pH values was studied by NMR and UV-visible spectroscopies. The results showed four equilibrium forms: the methylpyranomalvidin-3-O-glucoside cation, the neutral quinoidal base, the respective anionic quinoidal base, and a dianionic base unprotonated at the methyl group. According to the NMR data, it seems that for methylpyranomalvidin-3-O-glucoside besides the acid-base equilibrium between the pyranoflavylium cation and the neutral quinoidal base, a new species is formed at pD 4.88-6.10. This is corroborated by the appearance of a new set of signals in the NMR spectrum that may be assigned to the formation of hemiketal/cis-chalcone species to a small extent. The two ionization constants (pK(a1) and pK(a2)) obtained by both methods (NMR and UV-visible) for methylpyranomalvidin-3-O-glucoside are in agreement (pK(a1) = 5.17 ± 0.03; pK(a2) = 8.85 ± 0.08; and pK(a1) = 4.57 ± 0.07; pK(a2) = 8.23 ± 0.04 obtained by NMR and UV-visible spectroscopies, respectively). Moreover, the fully dianionic unprotonated form (at the methyl group) of the methylpyranomalvidin-3-O-glucoside is converted slowly into a new structure that displays a yellow color at basic pH. On the basis of the results obtained through LC-MS and NMR, the proposed structure was found to correspond to the flavonol syringetin-3-glucoside.

  17. Lanthanide complexes of macrocyclic polyoxovanadates by VO4 units: synthesis, characterization, and structure elucidation by X-ray crystallography and EXAFS spectroscopy.

    Science.gov (United States)

    Nishio, Masaki; Inami, Shinnosuke; Katayama, Misaki; Ozutsumi, Kazuhiko; Hayashi, Yoshihito

    2012-01-16

    Reactions of a tetravanadate anion, [V(4)O(12)](4-), with a series of lanthanide(III) salts yield three types of lanthanide complexes of macrocyclic polyoxovanadates: (Et(4)N)(6)[Ln(III)V(9)O(27)] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6)], (Et(4)N)(5)[(H(2)O)Ho(III)(V(4)O(12))(2)] (7), and (Et(4)N)(7)[Ln(III)V(10)O(30)] [Ln = Er (8), Tm (9), Yb (10), Lu (11)]. Lanthanide complexes 1-11 are isolated and characterized by IR, elemental analysis, single-crystal X-ray diffraction, and extended X-ray absorption fine structure spectroscopy (EXAFS). Lanthanide complexes 1-6 are composed of a square-antiprism eight-coordinated Ln(III) center with a macrocyclic polyoxovanadate that is constructed from nine VO(4) tetrahedra through vertex sharing. The structure of 7 is composed of a seven-coordinated Ho(III) center, which exhibits a capped trigonal-prism coordination environment by the sandwiching of two cyclic tetravanadates with a capping H(2)O ligand. Lanthanide complexes 8-11 have a six-coordinated Ln(III) center with a 10-membered vanadate ligand. The structural trend to adopt a larger coordination number for a larger lanthanide ion among the three types of structures is accompanied by a change in the vanadate ring sizes. These lanthanide complexes are examined by EXAFS spectroscopies on lanthanide L(III) absorption edges, and the EXAFS oscillations of each of the samples in the solid state and in acetonitrile are identical. The Ln-O and Ln···V bond lengths obtained from fits of the EXAFS data are consistent with the data from the single-crystal X-ray studies, reflecting retention of the structures in acetonitrile.

  18. Catalysis of GTP hydrolysis by small GTPases at atomic detail by integration of X-ray crystallography, experimental, and theoretical IR spectroscopy.

    Science.gov (United States)

    Rudack, Till; Jenrich, Sarah; Brucker, Sven; Vetter, Ingrid R; Gerwert, Klaus; Kötting, Carsten

    2015-10-02

    Small GTPases regulate key processes in cells. Malfunction of their GTPase reaction by mutations is involved in severe diseases. Here, we compare the GTPase reaction of the slower hydrolyzing GTPase Ran with Ras. By combination of time-resolved FTIR difference spectroscopy and QM/MM simulations we elucidate that the Mg(2+) coordination by the phosphate groups, which varies largely among the x-ray structures, is the same for Ran and Ras. A new x-ray structure of a Ran·RanBD1 complex with improved resolution confirmed this finding and revealed a general problem with the refinement of Mg(2+) in GTPases. The Mg(2+) coordination is not responsible for the much slower GTPase reaction of Ran. Instead, the location of the Tyr-39 side chain of Ran between the γ-phosphate and Gln-69 prevents the optimal positioning of the attacking water molecule by the Gln-69 relative to the γ-phosphate. This is confirmed in the RanY39A·RanBD1 crystal structure. The QM/MM simulations provide IR spectra of the catalytic center, which agree very nicely with the experimental ones. The combination of both methods can correlate spectra with structure at atomic detail. For example the FTIR difference spectra of RasA18T and RanT25A mutants show that spectral differences are mainly due to the hydrogen bond of Thr-25 to the α-phosphate in Ran. By integration of x-ray structure analysis, experimental, and theoretical IR spectroscopy the catalytic center of the x-ray structural models are further refined to sub-Å resolution, allowing an improved understanding of catalysis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Catalysis of GTP Hydrolysis by Small GTPases at Atomic Detail by Integration of X-ray Crystallography, Experimental, and Theoretical IR Spectroscopy*

    Science.gov (United States)

    Rudack, Till; Jenrich, Sarah; Brucker, Sven; Vetter, Ingrid R.; Gerwert, Klaus; Kötting, Carsten

    2015-01-01

    Small GTPases regulate key processes in cells. Malfunction of their GTPase reaction by mutations is involved in severe diseases. Here, we compare the GTPase reaction of the slower hydrolyzing GTPase Ran with Ras. By combination of time-resolved FTIR difference spectroscopy and QM/MM simulations we elucidate that the Mg2+ coordination by the phosphate groups, which varies largely among the x-ray structures, is the same for Ran and Ras. A new x-ray structure of a Ran·RanBD1 complex with improved resolution confirmed this finding and revealed a general problem with the refinement of Mg2+ in GTPases. The Mg2+ coordination is not responsible for the much slower GTPase reaction of Ran. Instead, the location of the Tyr-39 side chain of Ran between the γ-phosphate and Gln-69 prevents the optimal positioning of the attacking water molecule by the Gln-69 relative to the γ-phosphate. This is confirmed in the RanY39A·RanBD1 crystal structure. The QM/MM simulations provide IR spectra of the catalytic center, which agree very nicely with the experimental ones. The combination of both methods can correlate spectra with structure at atomic detail. For example the FTIR difference spectra of RasA18T and RanT25A mutants show that spectral differences are mainly due to the hydrogen bond of Thr-25 to the α-phosphate in Ran. By integration of x-ray structure analysis, experimental, and theoretical IR spectroscopy the catalytic center of the x-ray structural models are further refined to sub-Å resolution, allowing an improved understanding of catalysis. PMID:26272610

  20. A low volume 3D-printed temperature-controllable cuvette for UV visible spectroscopy.

    Science.gov (United States)

    Pisaruka, Jelena; Dymond, Marcus K

    2016-10-01

    We report the fabrication of a 3D-printed water-heated cuvette that fits into a standard UV visible spectrophotometer. Full 3D-printable designs are provided and 3D-printing conditions have been optimised to provide options to print the cuvette in either acrylonitrile butadiene styrene or polylactic acid polymers, extending the range of solvents that are compatible with the design. We demonstrate the efficacy of the cuvette by determining the critical micelle concentration of sodium dodecyl sulphate at 40 °C, the molar extinction coefficients of cobalt nitrate and dsDNA and by reproducing the thermochromic UV visible spectrum of a mixture of cobalt chloride, water and propan-2-ol. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. UV spectroscopy including ISM line absorption: of the exciting star of Abell 35

    Science.gov (United States)

    Ziegler, M.; Rauch, T.; Werner, K.; Kruk, J. W.

    Reliable spectral analysis that is based on high-resolution UV observations requires an adequate, simultaneous modeling of the interstellar line absorption and reddening. In the case of the central star of the planetary nebula Abell 35, BD-22 3467, we demonstrate our current standard spectral-analysis method that is based on the Tübingen NLTE Model-Atmosphere Package (TMAP). We present an on- going spectral analysis of FUSE and HST/STIS observations of BD-22 3467.

  2. UV-Vis Ratiometric Resonance Synchronous Spectroscopy for Determination of Nanoparticle and Molecular Optical Cross Sections.

    Science.gov (United States)

    Nettles, Charles B; Zhou, Yadong; Zou, Shengli; Zhang, Dongmao

    2016-03-01

    Demonstrated herein is a UV-vis Ratiometric Resonance Synchronous Spectroscopic (R2S2, pronounced as "R-two-S-two" for simplicity) technique where the R2S2 spectrum is obtained by dividing the resonance synchronous spectrum of a NP-containing solution by the solvent resonance synchronous spectrum. Combined with conventional UV-vis measurements, this R2S2 method enables experimental quantification of the absolute optical cross sections for a wide range of molecular and nanoparticle (NP) materials that range optically from pure photon absorbers or scatterers to simultaneous photon absorbers and scatterers, simultaneous photon absorbers and emitters, and all the way to simultaneous photon absorbers, scatterers, and emitters in the UV-vis wavelength region. Example applications of this R2S2 method were demonstrated for quantifying the Rayleigh scattering cross sections of solvents including water and toluene, absorption and resonance light scattering cross sections for plasmonic gold nanoparticles, and absorption, scattering, and on-resonance fluorescence cross sections for semiconductor quantum dots (Qdots). On-resonance fluorescence quantum yields were quantified for the model molecular fluorophore Eosin Y and fluorescent Qdots CdSe and CdSe/ZnS. The insights and methodology presented in this work should be of broad significance in physical and biological science research that involves photon/matter interactions.

  3. Indonesian palm civet coffee discrimination using UV-visible spectroscopy and several chemometrics methods

    International Nuclear Information System (INIS)

    Yulia, M; Suhandy, D

    2017-01-01

    Indonesian palm civet coffee or kopi luwak (Indonesian words for coffee and palm civet) is well known as the world’s priciest and rarest coffee. To protect the authenticity of luwak coffee and protect consumer from luwak coffee adulteration, it is very important to develop a simple and inexpensive method to discriminate between civet and non-civet coffee. The discrimination between civet and non-civet coffee in ground roasted (powder) samples is very challenging since it is very difficult to distinguish between the two by using conventional method. In this research, the use of UV-Visible spectra combined with two chemometric methods, SIMCA and PLS-DA, was evaluated to discriminate civet and non-civet ground coffee samples. The spectral data of civet and non-civet coffee were acquired using UV-Vis spectrometer (Genesys™ 10S UV-Vis, Thermo Scientific, USA). The result shows that using both supervised discrimination methods: SIMCA and PLS-DA, all samples were correctly classified into their corresponding classes with 100% rate for accuracy, sensitivity and specificity, respectively. (paper)

  4. Solar Coronal UV Spectroscopy for Solar Wind and SEP Acceleration Investigations

    Science.gov (United States)

    Moses, John Daniel; Ko, Yuan-Kuen; Laming, John Martin; Strachan, Leonard; Tun Beltran, Samuel

    2015-04-01

    Of all the new areas of solar physics opened by the landmark SOHO mission, the scientific discoveries of the Ultraviolet Coronagraph Spectrometer (UVCS) are unique in both the importance of the new questions raised by these observations and the lack of subsequent investigations to resolve these questions. For example, the first direct evidence of wave-particle coupling as an acceleration mechanism for the solar wind was obtained from UVCS spectro-coronagraphic observations, yet the real limits on the ratio of the parallel to perpendicular ion temperatures (with respect to the magnetic field) in coronal holes and streamers is still unresolved. Another unresolved issue is the role of suprathermal seed particles in rapid diffusive shock acceleration of SEPs. Although the theory has been placed on firmer theoretical ground by recent in situ investigations, observations of these suprathermal particles in the corona was never conclusively obtained with UVCS.Any follow-on UV Spectro-coronagraph must possess two improvements over UVCS in order to address the questions raised during the SOHO mission: 1) increased effective aperture and 2) improved spectrographic contrast (i.e. reduced scattered light). Technological developments in optics, optical design, UV detectors, composite structures, cleanliness control and electronics make it possible to achieve the requisite improvements in a next-generation UV spectro-coronagraph within the constraints of an affordable mission. We discuss specific instrument and mission approaches developed over the last 5 years and the feasibility of implementing them within the next 5 years.

  5. Missed opportunities in crystallography.

    Science.gov (United States)

    Dauter, Zbigniew; Jaskolski, Mariusz

    2014-09-01

    Scrutinized from the perspective of time, the giants in the history of crystallography more than once missed a nearly obvious chance to make another great discovery, or went in the wrong direction. This review analyzes such missed opportunities focusing on macromolecular crystallographers (using Perutz, Pauling, Franklin as examples), although cases of particular historical (Kepler), methodological (Laue, Patterson) or structural (Pauling, Ramachandran) relevance are also described. Linus Pauling, in particular, is presented several times in different circumstances, as a man of vision, oversight, or even blindness. His example underscores the simple truth that also in science incessant creativity is inevitably connected with some probability of fault. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  6. Online UV-visible spectroscopy and multivariate curve resolution as powerful tool for model-free investigation of laccase-catalysed oxidation.

    Science.gov (United States)

    Kandelbauer, A; Kessler, W; Kessler, R W

    2008-03-01

    The laccase-catalysed transformation of indigo carmine (IC) with and without a redox active mediator was studied using online UV-visible spectroscopy. Deconvolution of the mixture spectra obtained during the reaction was performed on a model-free basis using multivariate curve resolution (MCR). Thereby, the time courses of educts, products, and reaction intermediates involved in the transformation were reconstructed without prior mechanistic assumptions. Furthermore, the spectral signature of a reactive intermediate which could not have been detected by a classical hard-modelling approach was extracted from the chemometric analysis. The findings suggest that the combined use of UV-visible spectroscopy and MCR may lead to unexpectedly deep mechanistic evidence otherwise buried in the experimental data. Thus, although rather an unspecific method, UV-visible spectroscopy can prove useful in the monitoring of chemical reactions when combined with MCR. This offers a wide range of chemists a cheap and readily available, highly sensitive tool for chemical reaction online monitoring.

  7. Time-resolved laser spectroscopy in the UV/VUV spectral region

    International Nuclear Information System (INIS)

    Bengtsson, J.

    1992-01-01

    Radiative lifetimes ranging from 3 to 500 ns were measured on various states of Ag, N, Se, Te and As, by recording the fluorescence light decay after excitation by a laser pulse. Ag was supplied by a collimated atomic beam while Se, Te and As were contained in quartz cells. Pulsed laser radiation, with a wavelength down to 185 nm, was generated by different set-ups, using Nd-YAG pumped dye lasers combined with non-linear crystals and Raman shifting. Short laser pulses were produced by a nitrogen laser or a distributed feedback dye laser. Two-photon processes and stepwise excitation were used to populate high-lying levels. Depletion spectroscopy, quantum-beat spectroscopy and optical double resonance spectroscopy were also performed

  8. Applications of UV/Vis Spectroscopy in Characterization and Catalytic Activity of Noble Metal Nanoparticles Fabricated in Responsive Polymer Microgels: A Review.

    Science.gov (United States)

    Begum, Robina; Farooqi, Zahoor H; Naseem, Khalida; Ali, Faisal; Batool, Madeeha; Xiao, Jianliang; Irfan, Ahmad

    2018-11-02

    Noble metal nanoparticles loaded smart polymer microgels have gained much attention due to fascinating combination of their properties in a single system. These hybrid systems have been extensively used in biomedicines, photonics, and catalysis. Hybrid microgels are characterized by using various techniques but UV/Vis spectroscopy is an easily available technique for characterization of noble metal nanoparticles loaded microgels. This technique is widely used for determination of size and shape of metal nanoparticles. The tuning of optical properties of noble metal nanoparticles under various stimuli can be studied using UV/Vis spectroscopic method. Time course UV/Vis spectroscopy can also be used to monitor the kinetics of swelling and deswelling of microgels and hybrid microgels. Growth of metal nanoparticles in polymeric network or growth of polymeric network around metal nanoparticle core can be studied by using UV/Vis spectroscopy. This technique can also be used for investigation of various applications of hybrid materials in catalysis, photonics, and sensing. This tutorial review describes the uses of UV/Vis spectroscopy in characterization and catalytic applications of responsive hybrid microgels with respect to recent research progress in this area.

  9. UV Raman spectroscopy of H2-air flames excited with a narrowband KrF laser

    Science.gov (United States)

    Shirley, John A.

    1990-01-01

    Raman spectra of H2 and H2O in flames excited by a narrowband KrF excimer laser are reported. Observations are made over a porous-plug, flat-flame burner reacting H2 in air, fuel-rich with nitrogen dilution to control the temperature, and with an H2 diffusion flame. Measurements made from UV Raman spectra show good agreement with measurements made by other means, both for gas temperature and relative major species concentrations. Laser-induced fluorescence interferences arising from OH and O2 are observed in emission near the Raman spectra. These interferences do not preclude Raman measurements, however.

  10. Separation and Determination of Hydroxyacetophenones: An Experiment in Preparative TLC and UV Spectroscopy.

    Science.gov (United States)

    Bick, I. R. C.; And Others

    1982-01-01

    Provides background information and methodology for an experiment in which a mixture of o-, m-, and p-hydroxyacetophenones are separated by thin-layer chromatography (TLC) and in which the constituents are identified and estimated by ultra-violet light spectroscopy. (Author/JN)

  11. UV/Vis spectroscopy of C60 embedded in water ice

    DEFF Research Database (Denmark)

    Cuylle, Steven; Linnartz, Harold; Thrower, John

    2012-01-01

    Electronic solid state spectra are recorded for C60 embedded in 40 K water ice using broad band direct absorption spectroscopy, and assigned with reference to existing matrix data. The results are interesting in view of the recent gas phase detection of fullerenes in the interstellar medium...

  12. Fibrillation mechanism of a model intrinsically disordered protein revealed by 2D correlation deep UV resonance Raman spectroscopy.

    Science.gov (United States)

    Sikirzhytski, Vitali; Topilina, Natalya I; Takor, Gaius A; Higashiya, Seiichiro; Welch, John T; Uversky, Vladimir N; Lednev, Igor K

    2012-05-14

    Understanding of numerous biological functions of intrinsically disordered proteins (IDPs) is of significant interest to modern life science research. A large variety of serious debilitating diseases are associated with the malfunction of IDPs including neurodegenerative disorders and systemic amyloidosis. Here we report on the molecular mechanism of amyloid fibrillation of a model IDP (YE8) using 2D correlation deep UV resonance Raman spectroscopy. YE8 is a genetically engineered polypeptide, which is completely unordered at neutral pH yet exhibits all properties of a fibrillogenic protein at low pH. The very first step of the fibrillation process involves structural rearrangements of YE8 at the global structure level without the detectable appearance of secondary structural elements. The formation of β-sheet species follows the global structural changes and proceeds via the simultaneous formation of turns and β-strands. The kinetic mechanism revealed is an important new contribution to understanding of the general fibrillation mechanism proposed for IDP.

  13. SAXS Combined with UV-vis Spectroscopy and QELS: Accurate Characterization of Silver Sols Synthesized in Polymer Matrices.

    Science.gov (United States)

    Bulavin, Leonid; Kutsevol, Nataliya; Chumachenko, Vasyl; Soloviov, Dmytro; Kuklin, Alexander; Marynin, Andrii

    2016-12-01

    The present work demonstrates a validation of small-angle X-ray scattering (SAXS) combining with ultra violet and visible (UV-vis) spectroscopy and quasi-elastic light scattering (QELS) analysis for characterization of silver sols synthesized in polymer matrices. Polymer matrix internal structure and polymer chemical nature actually controlled the sol size characteristics. It was shown that for precise analysis of nanoparticle size distribution these techniques should be used simultaneously. All applied methods were in good agreement for the characterization of size distribution of small particles (less than 60 nm) in the sols. Some deviations of the theoretical curves from the experimental ones were observed. The most probable cause is that nanoparticles were not entirely spherical in form.

  14. Heavy-ion-induced sucrose radicals investigated using EPR and UV spectroscopy

    Science.gov (United States)

    Nakagawa, Kouichi; Karakirova, Yordanka; Yordanov, Nicola D.

    2015-01-01

    The potential use of a sucrose dosimeter for estimating both linear energy transfer (LET) and the absorbed dose of heavy ion and X-ray radiation was investigated. The stable free radicals were produced when sucrose was irradiated with heavy ions, such as helium, carbon, silicon and neon ions, and when the X-ray radiation was similar to the obtained electron paramagnetic resonance (EPR) spectra, which were ∼7 mT wide and composed of several hyperfine structures. In addition, the total spin concentration resulting from heavy-ion irradiation increased linearly as the absorbed dose increased, and decreased logarithmically as the LET increased. These empirical relations imply that the LET at a certain dose can be determined from the spin concentration. For sucrose and alanine, both cross-sections following C-ion irradiation with a 50 Gy dose were ∼1.3 × 10−12 [μm2], taking into account the molecular size of the samples. The values of these cross-sections imply that multiple ionizing particles were involved in the production of stable radicals. Furthermore, UV absorbance at 267 nm of an aqueous solution of irradiated sucrose was found to linearly increase with increasing absorbed dose. Therefore, the EPR and UV results suggest that sucrose can be a useful dosimeter for heavy-ion irradiation. PMID:25480828

  15. Interaction betwen Lead and Bone Protein to Affect Bone Calcium Level Using UV-Vis Spectroscopy

    Science.gov (United States)

    Noor, Z.; Azharuddin, A.; Aflanie, I.; Kania, N.; Suhartono, E.

    2018-05-01

    This present study aim to evaluate the interactions between lead (Pb) and with bone protein by UV-Vis approach. In addition, this prsent study also aim to investigate the effect of Pb on bone calcium (Ca) level. The present study was a true experimental study design to examine the impact of Pb exposure in bone of male rats (Rattus novergicus). The study involved 5 groups, P1 was the control group, while the other (P2-P5) were the case group with exposure of Pb in different concentration within 4 weeks. At the end of the exposure, the interaction between Pb and protein was determined using UV-Vis spectrophotometric method, and the Ca level was determined using permanganometric method. The results shows that that there is an interaction between Pb and bone protein. The result also shows that the value of the binding constant of Protein-Pb is 32.71. It means Pb have an high affinity to bind with bone protein, which promote a further reaction to induced the release of bone Ca from the bone protein. In conclusion, this present study found an obvious relationship between Pb and bone protein which promote a further reaction to increase the releasing of bone calcium.

  16. Co(II) Coordination in Prokaryotic Zinc Finger Domains as Revealed by UV-Vis Spectroscopy

    Science.gov (United States)

    Sivo, Valeria; D'Abrosca, Gianluca; Russo, Luigi; Iacovino, Rosa; Pedone, Paolo Vincenzo; Fattorusso, Roberto

    2017-01-01

    Co(II) electronic configuration allows its use as a spectroscopic probe in UV-Vis experiments to characterize the metal coordination sphere that is an essential component of the functional structure of zinc-binding proteins and to evaluate the metal ion affinities of these proteins. Here, exploiting the capability of the prokaryotic zinc finger to use different combinations of residues to properly coordinate the structural metal ion, we provide the UV-Vis characterization of Co(II) addition to Ros87 and its mutant Ros87_C27D which bears an unusual CysAspHis2 coordination sphere. Zinc finger sites containing only one cysteine have been infrequently characterized. We show for the CysAspHis2 coordination an intense d-d transition band, blue-shifted with respect to the Cys2His2 sphere. These data complemented by NMR and CD data demonstrate that the tetrahedral geometry of the metal site is retained also in the case of a single-cysteine coordination sphere. PMID:29386985

  17. Spontaneous Isomerization of Peptide Cation Radicals Following Electron Transfer Dissociation Revealed by UV-Vis Photodissociation Action Spectroscopy.

    Science.gov (United States)

    Imaoka, Naruaki; Houferak, Camille; Murphy, Megan P; Nguyen, Huong T H; Dang, Andy; Tureček, František

    2018-01-16

    Peptide cation radicals of the z-type were produced by electron transfer dissociation (ETD) of peptide dications and studied by UV-Vis photodissociation (UVPD) action spectroscopy. Cation radicals containing the Asp (D), Asn (N), Glu (E), and Gln (Q) residues were found to spontaneously isomerize by hydrogen atom migrations upon ETD. Canonical N-terminal [z 4 + H] +● fragment ion-radicals of the R-C ● H-CONH- type, initially formed by N-C α bond cleavage, were found to be minor components of the stable ion fraction. Vibronically broadened UV-Vis absorption spectra were calculated by time-dependent density functional theory for several [ ● DAAR + H] + isomers and used to assign structures to the action spectra. The potential energy surface of [ ● DAAR + H] + isomers was mapped by ab initio and density functional theory calculations that revealed multiple isomerization pathways by hydrogen atom migrations. The transition-state energies for the isomerizations were found to be lower than the dissociation thresholds, accounting for the isomerization in non-dissociating ions. The facile isomerization in [ ● XAAR + H] + ions (X = D, N, E, and Q) was attributed to low-energy intermediates having the radical defect in the side chain that can promote hydrogen migration along backbone C α positions. A similar side-chain mediated mechanism is suggested for the facile intermolecular hydrogen migration between the c- and [z + H] ● -ETD fragments containing Asp, Asn, Glu, and Gln residues. Graphical Abstract ᅟ.

  18. Probing the Behaviors of Gold Nanorods in Metastatic Breast Cancer Cells Based on UV-vis-NIR Absorption Spectroscopy

    Science.gov (United States)

    Zhang, Weiqi; Ji, Yinglu; Meng, Jie; Wu, Xiaochun; Xu, Haiyan

    2012-01-01

    In this work, behaviors of positively-charged AuNRs in a highly metastatic tumor cell line MDA-MB-231 are examined based on UV-vis-NIR absorption spectroscopy in combination with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and dark-field microscopic observation. It is found that characteristic surface plasmon resonance (SPR) peaks of AuNRs can be detected using spectroscopic method within living cells that have taken up AuNRs. The peak area of transverse SPR band is shown to be proportionally related to the amount of AuNRs in the cells determined with ICP-MS, which suggests a facile and real time quantification method for AuNRs in living cells. The shape of longitudinal SPR band in UV-vis-NIR spectrum reflects the aggregation state of AuNRs in the cells during the incubation period, which is proved by TEM and microscopic observations. Experimental results reveal that AuNRs are internalized by the cells rapidly; the accumulation, distribution and aggregation of AuNRs in the cells compartments are time and dose dependent. The established spectroscopic analysis method can not only monitor the behaviors of AuNRs in living cells but may also be helpful in choosing the optimum laser stimulation wavelength for anti-tumor thermotherapy. PMID:22384113

  19. Spontaneous Isomerization of Peptide Cation Radicals Following Electron Transfer Dissociation Revealed by UV-Vis Photodissociation Action Spectroscopy

    Science.gov (United States)

    Imaoka, Naruaki; Houferak, Camille; Murphy, Megan P.; Nguyen, Huong T. H.; Dang, Andy; Tureček, František

    2018-01-01

    Peptide cation radicals of the z-type were produced by electron transfer dissociation (ETD) of peptide dications and studied by UV-Vis photodissociation (UVPD) action spectroscopy. Cation radicals containing the Asp (D), Asn (N), Glu (E), and Gln (Q) residues were found to spontaneously isomerize by hydrogen atom migrations upon ETD. Canonical N-terminal [z4 + H]+● fragment ion-radicals of the R-C●H-CONH- type, initially formed by N-Cα bond cleavage, were found to be minor components of the stable ion fraction. Vibronically broadened UV-Vis absorption spectra were calculated by time-dependent density functional theory for several [●DAAR + H]+ isomers and used to assign structures to the action spectra. The potential energy surface of [●DAAR + H]+ isomers was mapped by ab initio and density functional theory calculations that revealed multiple isomerization pathways by hydrogen atom migrations. The transition-state energies for the isomerizations were found to be lower than the dissociation thresholds, accounting for the isomerization in non-dissociating ions. The facile isomerization in [●XAAR + H]+ ions (X = D, N, E, and Q) was attributed to low-energy intermediates having the radical defect in the side chain that can promote hydrogen migration along backbone Cα positions. A similar side-chain mediated mechanism is suggested for the facile intermolecular hydrogen migration between the c- and [z + H]●-ETD fragments containing Asp, Asn, Glu, and Gln residues. [Figure not available: see fulltext.

  20. Macromolecular crystallography using synchrotron radiation

    International Nuclear Information System (INIS)

    Bartunik, H.D.; Phillips, J.C.; Fourme, R.

    1982-01-01

    The use of synchrotron X-ray sources in macromolecular crystallography is described. The properties of synchrotron radiation relevant to macromolecular crystallography are examined. The applications discussed include anomalous dispersion techniques, the acquisition of normal and high resolution data, and kinetic studies of structural changes in macromolecules; protein data are presented illustrating these applications. The apparatus used is described including information on the electronic detectors, the monitoring of the incident beam and crystal cooling. (U.K.)

  1. Acoustic properties of nanoscale oxide heterostructures probed by UV Raman spectroscopy

    International Nuclear Information System (INIS)

    Bruchhausen, A; Lanzillotti-Kimura, N D; Fainstein, A; Soukiassian, A; Tenne, D A; Schlom, D; Xi, X X; Cantarero, A

    2007-01-01

    We study high quality molecular-beam epitaxy grown BaTiO 3 /SrTiO 3 superlat-tices using ultraviolet Raman spectroscopy. In the low energy spectral region, acoustic phonon doublets are observed. These are due to the artificial superlattice periodicity and consequent folding of the acoustic phonon dispersion. From the study of samples with different BaTiO 3 /SrTiO 3 layer thicknesses the effective sound velocities within each of the layers are obtained

  2. Acoustic properties of nanoscale oxide heterostructures probed by UV Raman spectroscopy

    Science.gov (United States)

    Bruchhausen, A.; Lanzillotti-Kimura, N. D.; Fainstein, A.; Soukiassian, A.; Tenne, D. A.; Schlom, D.; Xi, X. X.; Cantarero, A.

    2007-12-01

    We study high quality molecular-beam epitaxy grown BaTiO3/SrTiO3 superlat-tices using ultraviolet Raman spectroscopy. In the low energy spectral region, acoustic phonon doublets are observed. These are due to the artificial superlattice periodicity and consequent folding of the acoustic phonon dispersion. From the study of samples with different BaTiO3/SrTiO3 layer thicknesses the effective sound velocities within each of the layers are obtained.

  3. Chemical composition and surfactant characteristics of marine foams investigated by means of UV-vis, FTIR and FTNIR spectroscopy.

    Science.gov (United States)

    Mecozzi, Mauro; Pietroletti, Marco

    2016-11-01

    In this study, we collected the ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) and Fourier transform near-infrared (FTNIR) spectra of marine foams from different sites and foams produced by marine living organisms (i.e. algae and molluscs) to retrieve information about their molecular and structural composition. UV-vis spectra gave information concerning the lipid and pigment contents of foams. FTIR spectroscopy gave a more detailed qualitative information regarding carbohydrates, lipids and proteins in addition with information about the mineral contents of foams. FTNIR spectra confirmed the presence of carbohydrates, lipids and proteins in foams. Then, due to the higher content of structural information of FTIR spectroscopy with respect to FTNIR and UV-vis, we join the FTIR spectra of marine foams to those of humic substance from marine sediments and to the spectra of foams obtained by living organisms. We submitted this resulting FTIR spectral dataset to statistical multivariate methods to investigate specific aspects of foams such as structural similarity among foams and in addition, contributions from the organic matter of living organisms. Cluster analysis (CA) evidenced several cases (i.e. clusters) of marine foams having high structural similarity with foams from vegetal and animal samples and with humic substance extracted from sediments. These results suggested that all the living organisms of the marine environment can give contributions to the chemical composition of foams. Moreover, as CA also evidenced cases of structural differences within foam samples, we applied two-dimensional correlation analysis (2DCORR) to the FTIR spectra of marine foams to investigate the molecular characteristics which caused these structural differences. Asynchronous spectra of two-dimensional correlation analysis showed that the structural heterogeneity among foam samples depended reasonably on the presence and on the qualitative difference of

  4. Time-of-flight spectroscopy of metastable photodissociation fragments in vacuum-UV

    International Nuclear Information System (INIS)

    Fisher, C.H.; Welge, K.H.

    1974-01-01

    Photofragment time-of-flight experiments carried out at photon energies > approximately 11.8eV (1050A) is reported. Processes of the kind AB+hν→A*+B have been investigated where A* is an electronically excited species in a metastable state that can be detected by Auger electron emission from metal surfaces. The present work has been concerned with the identification of dissociation processes from N 2 O, CO 2 , and OCS, measurement of recoil energies and, for the first time, also angular dependent experiments. One objective of the work was to further explore the potential of such studies in the vacuum uv. Their feasibility was demonstrated previously in preliminary experiments

  5. Interference-Blind Microfluidic Sensor for Ascorbic Acid Determination by UV/vis Spectroscopy

    DEFF Research Database (Denmark)

    Bi, Hongyan; Oliveira Fernandes, Ana Carolina; Cardoso, Susana

    2016-01-01

    A microfluidic sensor is developed and targeted at specific ingredients determination in drug/food/beverage matrices. The surface of a serpentine polydimethylsiloxane (PDMS) microchannel is modified by enzyme via physisorption. When solutions containing target ingredients pass through...... the microfluidic channel, enzyme-catalyzed reaction occurs and only converts the target molecules to its products. The whole process is monitored by an end-channel UV/vis spectroscopic detection. Ascorbate oxidase and L-ascorbic acid (AA) are taken as enzyme-substrate model in this study to investigate......, specific, and accurate, and can be potentially used for fast quantification of ingredient in samples with complex matrix background. It is promising to be widely spread in food industry and quality control department...

  6. Determination of pK(a) of felodipine using UV-Visible spectroscopy.

    Science.gov (United States)

    Pandey, M M; Jaipal, A; Kumar, A; Malik, R; Charde, S Y

    2013-11-01

    In the present study, for the first time, experimental pKa value of felodipine is reported. Dissociation constant, pKa, is one of the very important physicochemical properties of drugs. It is of paramount significance from the perspective of pharmaceutical analysis and dosage form design. The method used for the pKa determination of felodipine was essentially a UV-Visible spectrophotometric method. The spectrophotometric method for the pKa determination was opted by acknowledging the established fact that spectrophotometric determination of pKa produces most precise values. The pKa of felodipine was found to be 5.07. Furthermore, the ruggedness of the determined value is also validated in this study in order to produce exact pKa of the felodipine. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Resonance Raman and UV-visible spectroscopy of black dyes on textiles.

    Science.gov (United States)

    Abbott, Laurence C; Batchelor, Stephen N; Smith, John R Lindsay; Moore, John N

    2010-10-10

    Resonance Raman and UV-visible diffuse reflectance spectra were recorded from samples of cotton, viscose, polyester, nylon, and acrylic textile swatches dyed black with one of seven single dyes, a mixture of two dyes, or one of seven mixtures of three dyes. The samples generally gave characteristic Raman spectra of the dyes, demonstrating that the technique is applicable for the forensic analysis of dyed black textiles. Survey studies of the widely used dye Reactive Black 5 show that essentially the same Raman spectrum is obtained on bulk sampling from the dye in solution, on viscose, on cotton at different uptakes, and on microscope sampling from the dye in cotton threads and single fibres. The effects of laser irradiation on the Raman bands and emission backgrounds from textile samples with and without dye are also reported. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  8. A microcomputer-controlled modulation technique for the detection of transient species in UV photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Lonkhuyzen, H. van; Muller, H.G.; Lange, C.A. de

    1980-01-01

    A microcomputer-controlled modulation method is described to measure UV photoelectron spectra of transient species generated in a microwave discharge. Spectra at low and high microwave power levels are simultaneously recorded and afterwards linearly combined in order to remove parent compound signals. The method is applied to discharged oxygen where the transition O 2 + ( 2 PHIsub(u)) 2 ( 1 Δsub(g)) becomes visible without interference from the parent molecule O 2 ( 3 Σsub(g) - ), and to discharged sulphur dioxide where SO( 3 Σ - ) and S( 3 P) photoelectron spectra are obtained free from SO 2 bands. Finally the build-up of transient bands as a function of time is recorded. (orig.)

  9. Characterization of a new Tc (V) - glucosazine complex by UV - VIS and IR spectroscopy

    International Nuclear Information System (INIS)

    Ganzerli Valentini, M.T.; Stella, R.; Maggi, L.

    1989-01-01

    A new radiopharmaceutical is proposed for brain and heart functional and radiodiagnostic studies. A Tc complex containing the glucose molecule and chelating groups that do not alter the basic chemical features of the molecule has been prepared. The ligand is formed by the combination of one hydrazine molecule with two sugar molecules and is the first product of the D-glucose-hydrazine reaction that in aqueous basic medium may proceed up to hydrazone and in acid medium up to osazone. These transformations are observed at pH>5 through the UV absorption peaks at 274 and 224 nm, and at pH 1 . UV absorption spectra of the complex, dissolved in water as well as in acetonitrile, have been recorded: the characteristic single peak at 274 nm and at 276 nm respectively for the two solvents is unaffected by the presence of free ligand, due to the quasi null absorption in this spectral region. Molar extinction coefficient is found equal to 20850 L.mol 1 .cm 1 in solutions whose Tc concentration was in the range 2x10 5 -5x10 4 M and the ligand 10 2 - 10 1 M. The IR absorption spectrum has a C=N stretching band at 1620 cm 1 which means that the acyclic form of the azine is predominant; other large and strong bands refer to OH stretching at 3300 cm 1 , to C-O stretching at 1020 cm 1 and to C-N stretching (typical of the cyclic form) at 1080 cm 1 . (author)

  10. Neutron protein crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-10-01

    X-ray diffraction of single crystal has enriched the knowledge of various biological molecules such as proteins, DNA, t-RNA, viruses, etc. It is difficult to make structural analysis of hydrogen atoms in a protein using X-ray crystallography, whereas neutron diffraction seems usable to directly determine the location of those hydrogen atoms. Here, neutron diffraction method was applied to structural analysis of hen egg-white lysozyme. Since the crystal size of a protein to analyze is generally small (5 mm{sup 3} at most), the neutron beam at the sample position in monochromator system was set to less than 5 x 5 mm{sup 2} and beam divergence to 0.4 degree or less. Neutron imaging plate with {sup 6}Li or Gd mixed with photostimulated luminescence material was used and about 2500 Bragg reflections were recorded in one crystal setting. A total of 38278 reflections for 2.0 A resolution were collected in less than 10 days. Thus, stereo views of Trp-111 omit map around the indol ring of Trp-111 was presented and the three-dimensional arrangement of 696H and 264D atoms in the lysozyme molecules was determined using the omit map. (M.N.)

  11. Characterization of silicon-oxide interfaces and organic monolayers by IR-UV ellipsometry and FTIR spectroscopy

    Science.gov (United States)

    Hess, P.; Patzner, P.; Osipov, A. V.; Hu, Z. G.; Lingenfelser, D.; Prunici, P.; Schmohl, A.

    2006-08-01

    VUV-laser-induced oxidation of Si(111)-(1×1):H, Si(100):H, and a-Si:H at 157 nm (F II laser) in pure O II and pure H IIO atmospheres was studied between 30°C and 250°C. The oxidation process was monitored in real time by spectroscopic ellipsometry (NIR-UV) and FTIR spectroscopy. The ellipsometric measurements could be simulated with a three-layer model, providing detailed information on the variation of the suboxide interface with the nature of the silicon substrate surface. Besides the silicon-dioxide and suboxide layer, a dense, disordered, roughly monolayer thick silicon layer was included, as found previously by molecular dynamics calculations. The deviations from the classical Deal-Grove mechanism and the self-limited growth of the ultrathin dioxide layers (TMS) groups and n-alkylthiol monolayers on gold-coated silicon. The C-H stretching vibrations of the methylene and methyl groups could be identified by FTIR spectroscopy and IR ellipsometry.

  12. A spirooxazine derivative as a highly sensitive cyanide sensor by means of UV-visible difference spectroscopy.

    Science.gov (United States)

    Zhu, Shaoyin; Li, Minjie; Sheng, Lan; Chen, Peng; Zhang, Yumo; Zhang, Sean Xiao-An

    2012-12-07

    A spirooxazine derivative 2-nitro-5a-(2-(4-dimethylaminophenyl)-ethylene)-6,6-dimethyl-5a,6-dihydro-12H-indolo[2,1-b][1,3]benzooxazine (P1) was explored as a sensitive cyanide probe. Different from conventional spiropyrans, P1 avoided locating the 3H-indolium cation and the 4-nitrophenolate anion in the same conjugated structure, which enhanced the positive charge of 3H-indolium cation so that the sensitivity and reaction speed were improved highly. UV-visible difference spectroscopy using P1 detection solution as a timely reference improved the measurement accuracy, prevented the error caused by the inherent absorption change of P1 solution with time. This enabled the "positive-negative alternative absorption peaks" in difference spectrum to be used as a finger-print to distinguish whether the spectral change was caused by cyanide. Benefiting from the special design of the molecular structure and the strategy of difference spectroscopy, P1 showed high selectivity and sensitivity for CN(-). A detection limit of 0.4 μM and a rate constant of 1.1 s(-1) were achieved.

  13. Effect of UV-A and UV-B irradiation on the metabolic profile of aqueous humor in rabbits analyzed by IH NMR Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Tessem, MB.; Bathen, T. F.; Čejková, Jitka; Midelfart, A.

    2005-01-01

    Roč. 46, č. 3 (2005), s. 776-781 ISSN 0146-0404 R&D Projects: GA ČR GA304/03/0419 Institutional research plan: CEZ:AV0Z50390512 Keywords : UV-A * UV-B Subject RIV: FF - HEENT, Dentistry Impact factor: 3.643, year: 2005

  14. Coherent Spectroscopy of Ultra-Cold Mercury for the UV to VUV

    Science.gov (United States)

    2015-11-20

    cw   laser   source.  The  spectroscopy   laser  system  utilizes  a   cw  fiber   laser  that  is  amplified  and...this,  we  first  lock  a   secondary  external  cavity  semiconductor   diode   laser  to  an  ultrastable  ULE  reference...system  to   the   diode   laser .  This

  15. Acoustic properties of nanoscale oxide heterostructures probed by UV Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bruchhausen, A [Instituto Balseiro and Centro Atomico Bariloche, Av. E. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Lanzillotti-Kimura, N D [Instituto Balseiro and Centro Atomico Bariloche, Av. E. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Fainstein, A [Instituto Balseiro and Centro Atomico Bariloche, Av. E. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Soukiassian, A [Department of Physics, Pennsylvania State University, University Park, PA, 16802 (United States); Tenne, D A [Department of Physics, Pennsylvania State University, University Park, PA, 16802 (United States); Schlom, D [Department of Physics, Pennsylvania State University, University Park, PA, 16802 (United States); Xi, X X [Department of Physics, Pennsylvania State University, University Park, PA, 16802 (United States); Cantarero, A [Materials Science Institute, University of Valencia, PO Box 22085, E-46071 Valencia (Spain)

    2007-12-15

    We study high quality molecular-beam epitaxy grown BaTiO{sub 3}/SrTiO{sub 3} superlat-tices using ultraviolet Raman spectroscopy. In the low energy spectral region, acoustic phonon doublets are observed. These are due to the artificial superlattice periodicity and consequent folding of the acoustic phonon dispersion. From the study of samples with different BaTiO{sub 3}/SrTiO{sub 3} layer thicknesses the effective sound velocities within each of the layers are obtained.

  16. In-line ATR-UV and Raman Spectroscopy for Monitoring API Dissolution Process During Liquid-Filled Soft-Gelatin Capsule Manufacturing.

    Science.gov (United States)

    Wan, Boyong; Zordan, Christopher A; Lu, Xujin; McGeorge, Gary

    2016-10-01

    Complete dissolution of the active pharmaceutical ingredient (API) is critical in the manufacturing of liquid-filled soft-gelatin capsules (SGC). Attenuated total reflectance UV spectroscopy (ATR-UV) and Raman spectroscopy have been investigated for in-line monitoring of API dissolution during manufacturing of an SGC product. Calibration models have been developed with both techniques for in-line determination of API potency. Performance of both techniques was evaluated and compared. The ATR-UV methodology was found to be able to monitor the dissolution process and determine the endpoint, but was sensitive to temperature variations. The Raman technique was also capable of effectively monitoring the process and was more robust to the temperature variation and process perturbations by using an excipient peak for internal correction. Different data preprocessing methodologies were explored in an attempt to improve method performance.

  17. New insight into protein-nanomaterial interactions with UV-visible spectroscopy and chemometrics: human serum albumin and silver nanoparticles.

    Science.gov (United States)

    Wang, Yong; Ni, Yongnian

    2014-01-21

    In recent years, great efforts have focused on the exploration and fabrication of protein nanoconjugates due to potential applications in many fields including bioanalytical science, biosensors, biocatalysis, biofuel cells and bio-based nanodevices. An important aspect of our understanding of protein nanoconjugates is to quantitatively understand how proteins interact with nanomaterials. In this report, human serum albumin (HSA) and citrate-coated silver nanoparticles (AgNPs) are selected as a case study of protein-nanomaterial interactions. UV-visible spectroscopy together with multivariate curve resolution by alternating least squares (MCR-ALS) algorithm is first exploited for the detailed study of AgNPs-HSA interactions. Introduction of the chemometrics tool allows extracting the kinetic profiles, spectra and distribution diagrams of two major absorbing pure species (AgNPs and AgNPs-HSA conjugate). These resolved profiles are then analysed to give the thermodynamic, kinetic and structural information of HSA binding to AgNPs. Transmission electron microscopy, circular dichroism spectroscopy and Fourier transform infrared spectroscopy are used to further characterize the complex system. Moreover, a sensitive spectroscopic biosensor for HSA is fabricated with the MCR-ALS resolved concentration of absorbing pure species. It is found that the linear range for the HSA nanosensor was from 1.9 nM to 45.0 nM with a detection limit of 0.9 nM. It is believed that the proposed method will play an important role in the fabrication and optimization of a robust nanobiosensor or cross-reactive sensors array for the detection and identification of biocomponents.

  18. WATSON: Detecting organic material in subsurface ice using deep-UV fluorescence and Raman spectroscopy

    Science.gov (United States)

    Eshelman, E.; Wanger, G.; Manatt, K.; Malaska, M.; Willis, M.; Abbey, W.; Doloboff, I.; Beegle, L. W.; DeFlores, L. P.; Priscu, J. C.; Lane, A. L.; Carrier, B. L.; Mellerowicz, B.; Kim, D.; Paulsen, G.; Zacny, K.; Bhartia, R.

    2017-12-01

    Future astrobiological missions to Europa and other ocean worlds may benefit from next-generation instrumentation capable of in situ organic and life detection in subsurface ice environments. WATSON (Wireline Analysis Tool for in Situ Observation of Northern ice sheets) is an instrument under development at NASA's Jet Propulsion Laboratory. WATSON contains high-TRL instrumentation developed for SHERLOC, the Mars 2020 deep-UV fluorescence and Raman spectrometer, including a 248.6 nm NeCu hollow cathode laser as an excitation source. In WATSON, these technologies provide spectroscopic capabilities highly sensitive to many organic compounds, including microbes, in an instrument package approximately 1.2 m long with a 101.6 mm diameter, designed to accommodate a 108 mm ice borehole. Interrogation into the ice wall with a laser allows for a non-destructive in situ measurement that preserves the spatial distribution of material within the ice. We report on a successful deployment of WATSON to Kangerlussuaq, Greenland, where the instrument was lowered to a 4.5 m depth in a hand-cored hole on the Kangerlussuaq sector of the Greenland ice sheet. Motorized stages within the instrument were used to raster a laser across cm-scale regions of the interior surface of the borehole, obtaining fluorescence spectral maps with a 200 µm spatial resolution and a spectral range from 265 nm to 440 nm. This region includes the UV emission bands of many aromatic compounds and microbes, and includes the water and ice Raman O-H stretching modes. We additionally report on experiments designed to inform an early-2018 deployment to Kangerlussuaq where WATSON will be incorporated into a Honeybee Robotics planetary deep drill, with a goal of drilling to a depth of 100 m and investigating the distribution of organic material within the ice sheet. These experiments include laboratory calibrations to determine the sensitivity to organic compounds embedded in ice at various depths, as well as

  19. The translucency of dental composites investigated by UV-VIS spectroscopy

    International Nuclear Information System (INIS)

    Dumitrescu, L. Silaghi; Pastrav, O.; Prejmerean, C.; Prodan, D.; Boboia, S.; Codruta, S.; Moldovan, M.

    2013-01-01

    Translucency is the property of a material to partially transmit and diffuse incident light, and can be described as a partial opacity or a state between complete opacity and complete transparency. The purpose of this study is to evaluate the translucency index of resin composites according to their chemical structure and to the light source used for curing. Our study was achieved on four commercial composite samples (30 mm × 2 mm) cured with two different lamps (Optilux - halogen bulb and Ultralight - LED). Measurements were made with a UV-VIS spectrophotometer, and the reflection spectrum was recorded in the 380-770 nm region on white and black, compared with a SPECTRALON standard white. For all materials cured with the LED lamp on the glossy sides, the best results were given by Tetric Evo Ceram followed by Filtek Supreme, Restacril RO and Premise. The measurements made on samples cured with an Optilux lamp, to the smooth and rough sides of the samples, revealed that the highest index of translucency is provided by Tetric Evo Ceram on the smooth side, followed by Filtek Supreme, Restacril RO and Premises. We can say that the translucency of the composites is mostly determined by the chemical composition of the material, which is observed from transmittance values recorded for each sample, and by the source of radiation applied on the sample

  20. The translucency of dental composites investigated by UV-VIS spectroscopy

    Science.gov (United States)

    Dumitrescu, L. Silaghi; Pastrav, O.; Prejmerean, C.; Prodan, D.; Boboia, S.; Codruta, S.; Moldovan, M.

    2013-11-01

    Translucency is the property of a material to partially transmit and diffuse incident light, and can be described as a partial opacity or a state between complete opacity and complete transparency. The purpose of this study is to evaluate the translucency index of resin composites according to their chemical structure and to the light source used for curing. Our study was achieved on four commercial composite samples (30 mm × 2 mm) cured with two different lamps (Optilux - halogen bulb and Ultralight - LED). Measurements were made with a UV-VIS spectrophotometer, and the reflection spectrum was recorded in the 380-770 nm region on white and black, compared with a SPECTRALON standard white. For all materials cured with the LED lamp on the glossy sides, the best results were given by Tetric Evo Ceram followed by Filtek Supreme, RestacrilRO and Premise. The measurements made on samples cured with an Optilux lamp, to the smooth and rough sides of the samples, revealed that the highest index of translucency is provided by Tetric Evo Ceram on the smooth side, followed by Filtek Supreme, RestacrilRO and Premises. We can say that the translucency of the composites is mostly determined by the chemical composition of the material, which is observed from transmittance values recorded for each sample, and by the source of radiation applied on the sample.

  1. Inline UV/Vis spectroscopy as PAT tool for hot-melt extrusion.

    Science.gov (United States)

    Wesholowski, Jens; Prill, Sebastian; Berghaus, Andreas; Thommes, Markus

    2018-01-11

    Hot-melt extrusion on co-rotating twin screw extruders is a focused technology for the production of pharmaceuticals in the context of Quality by Design. Since it is a continuous process, the potential for minimizing product quality fluctuation is enhanced. A typical application of hot-melt extrusion is the production of solid dispersions, where an active pharmaceutical ingredient (API) is distributed within a polymer matrix carrier. For this dosage form, the product quality is related amongst others to the drug content. This can be monitored on- or inline as critical quality attribute by a process analytical technology (PAT) in order to meet the specific requirements of Quality by Design. In this study, an inline UV/Vis spectrometer from ColVisTec was implemented in an early development twin screw extruder and the performance tested in accordance to the ICH Q2 guideline. Therefore, two API (carbamazepine and theophylline) and one polymer matrix (copovidone) were considered with the main focus on the quantification of the drug load. The obtained results revealed the suitability of the implemented PAT tool to quantify the drug load in a typical range for pharmaceutical applications. The effort for data evaluation was minimal due to univariate data analysis, and in combination with a measurement frequency of 1 Hz, the system is sufficient for real-time data acquisition.

  2. Time-resolved UV spectroscopy on ammonia excited by a pulsed CO2 laser

    International Nuclear Information System (INIS)

    Holbach, H.

    1980-07-01

    This work investigates the excitation of ammonia by a pulsed CO 2 laser, in particular the processes associated with collisions with argon. It was prompted by two previous observations: the previously reported infrared multiphoton dissociation of NH 3 under nearly collisionless conditions, and the ill understood excitation mechanism of apparently nonresonant low vibrational levels in the presence of Ar. Based on recent spectroscopic data, all vibrational-rotational levels were determined which are simultaneously excited by different CO 2 laser lines. Transitions between the 1 + and 2 - vibrational levels were also taken into account. The linewidth in these calculations was dominated by power broadening, which generates a half width at half maximum of 0.36 cm -1 at the typical power density of 10 MW/cm 2 . In order to reproduce published experimental absorption data, it proved necessary to take account all transitions within a distance of 20 cm -1 from the laser line. This fact implies in most cases the simultaneous population of a large number of vibrational-rotational levels. The population of levels by absorption or by subsequent collisional processes was probed by time-resolved absorption measurement of vibrational bands and their rotational envelope in the near UV. Time resolution (5...10) was sufficient to observe rotational relaxation within individual vibrational levels. Characteristic differences were found for the various excitation lines. (orig.) [de

  3. Determination of two capsaicinoids in analgesic transdermal patches using RP-HPLC and UV spectroscopy

    Directory of Open Access Journals (Sweden)

    F. Kobarfard

    2017-11-01

    Full Text Available Background and objectives: At the present time, a considerable frontier in the administration of therapeutic medications is transdermal drug delivery. Methods: In this study, a rapid, precise, sensitive and selective reversed-phasehigh performance liquid chromatography (RP-HPLC method has been evaluated, developed and validated to separate and quantitate capsaicin and dihydrocapsaicin (main active agents in analgesic dermal patches produced in Iran. Results: After isolation from laminated adhesive patches, capsaicinoids were analyzed on Lichrospher C18 analytical columns with reversed phase, using a mobile phase composition of methanol and distilled water (70:30 v/v and without any buffer (pH=6.5. The flow rate was 1 mL/min and the UV detector was operating at 281 nm. The assay was found to be linear over the range of 0.1-1.0 mg/mL. All validation parameters were within the acceptable range. Conclusion: It seems that the developed method was fairly sensitive and reliable in measuring capsaicinoids in commercially available analgesic transdermal patches in Iran.

  4. The reasons for the color green fluorite Mehmandooye cover using UV spectroscopy and XRF results

    Science.gov (United States)

    Pirzadeh, Sara; Zahiri, Reza

    2016-04-01

    Fluorite mineral or fluorine with chemical formula CaF2 is most important mineralfluor in nature. This mineral crystallization to colors yellow, green, pink, blue, purple, colorless and sometimes black andin cubic system crystallized.assemi transparent and glass with polished.fluoritethe purity include 48/9% fluoreand 51/9% calcium. How the creation colors in minerals different greatly indebted to Kurt Nassau research from Bell Labs, Murray Hill, New Jersey.almostall the mechanisms that cause color in minerals, are the result of the interaction of light waves with the electrons The main factors affecting the color generation include the following: 1)the presence of a constructive element inherent (essential ingredient mineral composition) 2)The presence of a minor impurities (such a element as involved in latticesolid solution) 3) appearancedefects in the crystal structure 4) There are some physical boundaries with distances very small and delicate, like blades out of the solution (which may be the play of colors or Chatvyansy) 5) Mixing mechanical impurities dispersed in a host mineral Based on the results of the analysis, XRF and UV spectrum and also based on the results of ICP, because the color green fluorite examined, the focus color (F_center) and also the presence of some elementsintermediate (such as Y (yttrium). [1] Bill, H., Calas, G. Color centres associated rare earth ions and the origin of coloration in natural fluorites// PhysChem Min, (1978), v 3, pp. 117-131.

  5. UV Spectroscopy of Star-Grazing Comets Within the 49 Ceti Debris Disk

    Science.gov (United States)

    Miles, Brittany E.; Roberge, Aki; Welsh, Barry

    2016-01-01

    We present the analysis of time-variable Doppler-shifted absorption features in far-UV spectra of the unusual 49 Ceti debris disk. This nearly edge-on disk is one of the brightest known and is one of the very few containing detectable amounts of circumstellar (CS) gas as well as dust. In our two visits of Hubble Space Telescope STIS spectra, variable absorption features are seen on the wings of lines arising from CII and CIV but not for any of the other CS absorption lines. Similar variable features have long been seen in spectra of the well-studied Beta Pictoris debris disk and attributed to the transits of star-grazing comets. We calculated the velocity ranges and apparent column densities of the 49 Cet variable gas, which appears to have been moving at velocities of tens to hundreds of kms(-1) relative to the central star. The velocities in the redshifted variable event seen in the second visit show that the maximum distances of the in falling gas at the time of transit were about 0.050.2 au from the central star. A preliminary attempt at a composition analysis of the redshifted event suggests that the C/O ratio in the in falling gas is super-solar, as it is in the bulk of the stable disk gas.

  6. From pirazoloquinolines to annulated azulene dyes: UV-VIS spectroscopy and quantum chemical study

    International Nuclear Information System (INIS)

    Gasiorski, P.; Danel, K.S.; Matusiewicz, M.; Uchacz, T.; Kityk, A.V.

    2010-01-01

    Paper reports UV-Vis absorption and photoluminescence spectra of 6-R derivatives (R=CH 3 , O-CH 3 , C(C 6 H 5 ) 3 , C 6 H 5 -N-C 10 H 7 ) of 4-(2-chlorophenyl)-1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline, belonging to pyrazoloquinoline (PQ) family, likewise its regioisomeric products 10-R derivatives of 6-phenyl-6H-5,6,7-triazadibenzo[f,h]naphtho[3,2,1-cd]azulene representing cyclized seven-membered annulated azulene (AA) dyes. Cyclization of PQs into AAs is accompanied by a significant red shift of the first optical absorption band. This finding agrees with the results of quantum-chemical calculations performed by means of the semiempirical method PM3. As the solvent polarity rises all the dyes exhibit a blue shift of the first absorption band and a red shift of the fluorescence band. Such opposite trends in solvatochromic behavior have been reproduced within the semiempirical calculations in combination with the Lippert-Mataga dielectric polarization model. Depending on solvent polarity AA dyes emit light in the green, green-yellow or orange range of the visible spectrum what may be of interest for potential luminescent or electroluminescent applications.

  7. UV-Vis spectroscopy and solvatochromism of the tyrosine kinase inhibitor AG-1478

    Science.gov (United States)

    Khattab, Muhammad; Wang, Feng; Clayton, Andrew H. A.

    2016-07-01

    The effect of twenty-one solvents on the UV-Vis spectrum of the tyrosine kinase inhibitor AG-1478 was investigated. The absorption spectrum in the range 300-360 nm consisted of two partially overlapping bands at approximately 340 nm and 330 nm. The higher energy absorption band was more sensitive to solvent and exhibited a peak position that varied from 327 nm to 336 nm, while the lower energy absorption band demonstrated a change in peak position from 340 nm to 346 nm in non-chlorinated solvents. The fluorescence spectrum of AG-1478 was particularly sensitive to solvent. The wavelength of peak intensity varied from 409 nm to 495 nm with the corresponding Stokes shift in the range of 64 nm to 155 nm (4536 cm- 1 to 9210 cm- 1). We used a number of methods to assess the relationship between spectroscopic properties and solvent properties. The detailed analysis revealed that for aprotic solvents, the peak position of the emission spectrum in wavenumber scale correlated with the polarity (dielectric constant or ET(30)) of the solvent. In protic solvents, a better correlation was observed between the hydrogen bonding power of the solvent and the position of the emission spectrum. Moreover, the fluorescence quantum yields were larger in aprotic solvents as compared to protic solvents. This analysis underscores the importance of polarity and hydrogen-bonding environment on the spectroscopic properties of AG-1478. These studies will assume relevance in understanding the interaction of AG-1478 in vitro and in vivo.

  8. Multichordal visible/near-UV spectroscopy on the DIII-D tokamak

    International Nuclear Information System (INIS)

    Seraydarian, R.P.; Burrell, K.H.; Groebner, R.J.

    1988-01-01

    A pair of visible/near-UV spectrometers with eight viewing chords apiece have been installed on the DIII-D tokamak. Each system views a neutral heating beam and can acquire up to 250 complete spectra from each chord with 5--20-ms time resolution. Each viewing chord covers 60 A with 0.27-A spectral resolution, and the chords span about (2)/(3) of the plasma's full width. By viewing Doppler-broadened spectral lines from charge exchange recombination (CER) reactions between beam neutrals and plasma ions, ion temperatures up to 4 keV have been measured, and the bulk Doppler shift of these same lines has yielded plasma rotation velocities up to 200 km/s. The constancy of temperature on a magnetic flux surface and the rigid rotor model of a flux surface have been confirmed. These instruments have also been used to measure the neutral beam deposition profile, and preliminary experimental results agree with theoretical calculations of the beam deposition profile

  9. Multichordal visible/near uv spectroscopy in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Seraydarian, R.P.; Burrell, K.H.; Groebner, R.J.

    1988-02-01

    A pair of visible/near uv spectrometers with eight viewing chords apiece have been installed on the DIII-D tokamak. Each system views a neutral heating beam, and can acquire up to 250 complete spectra from each chord with 5-20 msec time resolution. Each viewing chord covers 60 A with 0.27 A spectral resolution, and the chords span about 2/3 of the plasma's full width. By viewing Doppler broadened spectral lines from charge exchange recombination (CER) reactions between beam neutrals and plasma ions, ion temperatures up to keV have been meassured, and the bulk Doppler shift of these same lines has yielded plasma rotation velocities up to 200 km/sec. The constancy of temperature on a magnetic flux surface and the rigid rotor model of a flux surface have been confirmed. These instruments have also been used to measure the neutral beam deposition profile, and preliminary experimental results agree with theoretical calculations of the beam deposition profile. 5 refs., 6 figs

  10. Dielectric spectroscopy of [P(NID2OD-T2)]n thin films: Effects of UV radiation on charge transport

    International Nuclear Information System (INIS)

    Sepulveda, Pablo I.; Rosado, Alexander O.; Pinto, Nicholas J.

    2014-01-01

    Poly[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide) -2,6-diyll-alt-5,5′-(2,2′-bithiophene)]-[P(ND12OD-T2)] n is a n-doped polymer that is stable in air. Low frequency (40 Hz–30 kHz) dielectric spectroscopy shows that the polymer impedance strength is reduced under ultra-violet (UV) radiation as a result of charge increase in the bulk polymer. Photo-excitation and the creation of electron-hole pairs and subsequent hole recombination with electron trapping species adsorbed by the polymer are suggested as possible doping mechanisms. The relaxation times were also faster in the presence of UV indicating multiple pathways for oscillating dipoles to relax. These results imply increased polymer conductance with corresponding enhancement of charge mobility due to reduced scattering in the presence of UV radiation. A thin film field effect transistor was fabricated using this polymer as the active material and characterized in the presence of UV radiation. As expected, the device exhibited n-type behavior with a charge mobility of 3.0 × 10 −3 cm 2 /V-s. Exposure to UV radiation increased the channel current, shifted the threshold voltage to more negative values and doubled the value of the mobility. These results are consistent with dielectric measurements and suggest an easy method of increasing device currents and charge mobility in this polymer via UV irradiation. - Highlights: • Ultra-violet (UV) radiation dopes the polymer. • The doping is n-type. • UV radiation enhances charge mobility without post polymer processing. • Dielectric spectroscopy and field effect transistor results are self-consistent

  11. Determination of elemental composition of coffee using UV-pulsed laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Gondal, M. A.; Baig, Umair; Dastageer, M. A.; Sarwar, Mohsin

    2016-01-01

    A detection system based on laser induced breakdown spectroscopy (LIBS) was built using 266 nm wavelength pulsed laser from the fourth harmonic of Nd:YAG laser, 500 mm spectrograph and gated ICCD camera with built-in delay generator. The LIBS system was used to study the elemental composition in coffee available in the local market of Saudi Arabia for the detection of elements in coffee samples. The LIBS spectrum of coffee sample revealed the presence magnesium, calcium, aluminum, copper, sodium, barium, bromine, cobalt, chromium, cerium manganese and molybdenum. Atomic transition line of sodium is used to study the parametric dependence of LIBS signal. The study of the dependence of LIBS signal on the laser pulse energy is proven to be linear and the dependence of LIBS signal on the time delay between the excitation and data acquisition showed a typical increase, a peak value and a decrease with the optimum excitation – acquisition delay at 400 ns.

  12. Determination of elemental composition of coffee using UV-pulsed laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gondal, M. A., E-mail: magondal@kfupm.edu.sa; Baig, Umair; Dastageer, M. A.; Sarwar, Mohsin [Laser Research Group, Physics Department, King Fahd University of Petroleum and Minerals, P.O Box 5047, Dhahran 31261 (Saudi Arabia)

    2016-06-10

    A detection system based on laser induced breakdown spectroscopy (LIBS) was built using 266 nm wavelength pulsed laser from the fourth harmonic of Nd:YAG laser, 500 mm spectrograph and gated ICCD camera with built-in delay generator. The LIBS system was used to study the elemental composition in coffee available in the local market of Saudi Arabia for the detection of elements in coffee samples. The LIBS spectrum of coffee sample revealed the presence magnesium, calcium, aluminum, copper, sodium, barium, bromine, cobalt, chromium, cerium manganese and molybdenum. Atomic transition line of sodium is used to study the parametric dependence of LIBS signal. The study of the dependence of LIBS signal on the laser pulse energy is proven to be linear and the dependence of LIBS signal on the time delay between the excitation and data acquisition showed a typical increase, a peak value and a decrease with the optimum excitation – acquisition delay at 400 ns.

  13. Deep rest-frame far-UV spectroscopy of the giant Lyman α emitter 'Himiko'

    DEFF Research Database (Denmark)

    Zabl, J.; Nørgaard-Nielsen, Hans Ulrik; Fynbo, J. P. U.

    2015-01-01

    We present deep 10 h VLT/XSHOOTER spectroscopy for an extraordinarily luminous and extended Ly alpha emitter at z = 6.595 referred to asHimiko and first discussed by Ouchi et al., with the purpose of constraining the mechanisms powering its strong emission. Complementary to the spectrum, we discuss...... near-infrared imaging data from the CANDELS survey. We find neither for He II nor any metal line a significant excess, with 3 σ upper limits of 6.8, 3.1, and 5.8 x 10-18 erg s-1 cm-2 for C IV λ 1549, He II λ 1640, C III] λ 1909, respectively, assuming apertures with 200 km s-1 widths and offset by -250...

  14. UV-Visible Spectroscopy-Based Quantification of Unlabeled DNA Bound to Gold Nanoparticles.

    Science.gov (United States)

    Baldock, Brandi L; Hutchison, James E

    2016-12-20

    DNA-functionalized gold nanoparticles have been increasingly applied as sensitive and selective analytical probes and biosensors. The DNA ligands bound to a nanoparticle dictate its reactivity, making it essential to know the type and number of DNA strands bound to the nanoparticle surface. Existing methods used to determine the number of DNA strands per gold nanoparticle (AuNP) require that the sequences be fluorophore-labeled, which may affect the DNA surface coverage and reactivity of the nanoparticle and/or require specialized equipment and other fluorophore-containing reagents. We report a UV-visible-based method to conveniently and inexpensively determine the number of DNA strands attached to AuNPs of different core sizes. When this method is used in tandem with a fluorescence dye assay, it is possible to determine the ratio of two unlabeled sequences of different lengths bound to AuNPs. Two sizes of citrate-stabilized AuNPs (5 and 12 nm) were functionalized with mixtures of short (5 base) and long (32 base) disulfide-terminated DNA sequences, and the ratios of sequences bound to the AuNPs were determined using the new method. The long DNA sequence was present as a lower proportion of the ligand shell than in the ligand exchange mixture, suggesting it had a lower propensity to bind the AuNPs than the short DNA sequence. The ratio of DNA sequences bound to the AuNPs was not the same for the large and small AuNPs, which suggests that the radius of curvature had a significant influence on the assembly of DNA strands onto the AuNPs.

  15. UV-Vis spectroscopy and solvatochromism of the tyrosine kinase inhibitor AG-1478.

    Science.gov (United States)

    Khattab, Muhammad; Wang, Feng; Clayton, Andrew H A

    2016-07-05

    The effect of twenty-one solvents on the UV-Vis spectrum of the tyrosine kinase inhibitor AG-1478 was investigated. The absorption spectrum in the range 300-360nm consisted of two partially overlapping bands at approximately 340nm and 330nm. The higher energy absorption band was more sensitive to solvent and exhibited a peak position that varied from 327nm to 336nm, while the lower energy absorption band demonstrated a change in peak position from 340nm to 346nm in non-chlorinated solvents. The fluorescence spectrum of AG-1478 was particularly sensitive to solvent. The wavelength of peak intensity varied from 409nm to 495nm with the corresponding Stokes shift in the range of 64nm to 155nm (4536cm(-1) to 9210cm(-1)). We used a number of methods to assess the relationship between spectroscopic properties and solvent properties. The detailed analysis revealed that for aprotic solvents, the peak position of the emission spectrum in wavenumber scale correlated with the polarity (dielectric constant or ET(30)) of the solvent. In protic solvents, a better correlation was observed between the hydrogen bonding power of the solvent and the position of the emission spectrum. Moreover, the fluorescence quantum yields were larger in aprotic solvents as compared to protic solvents. This analysis underscores the importance of polarity and hydrogen-bonding environment on the spectroscopic properties of AG-1478. These studies will assume relevance in understanding the interaction of AG-1478 in vitro and in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Quantitative monitoring of an activated sludge reactor using on-line UV-visible and near-infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sarraguca, Mafalda C.; Lopes, Joao A. [Universidade do Porto, REQUIMTE, Servico de Quimica-Fisica, Faculdade de Farmacia, Porto (Portugal); Paulo, Ana; Alves, Madalena M.; Dias, Ana M.A.; Ferreira, Eugenio C. [Universidade do Minho, IBB - Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Braga (Portugal)

    2009-10-15

    The performance of an activated sludge reactor can be significantly enhanced through use of continuous and real-time process-state monitoring, which avoids the need to sample for off-line analysis and to use chemicals. Despite the complexity associated with wastewater treatment systems, spectroscopic methods coupled with chemometric tools have been shown to be powerful tools for bioprocess monitoring and control. Once implemented and optimized, these methods are fast, nondestructive, user friendly, and most importantly, they can be implemented in situ, permitting rapid inference of the process state at any moment. In this work, UV-visible and NIR spectroscopy were used to monitor an activated sludge reactor using in situ immersion probes connected to the respective analyzers by optical fibers. During the monitoring period, disturbances to the biological system were induced to test the ability of each spectroscopic method to detect the changes in the system. Calibration models based on partial least squares (PLS) regression were developed for three key process parameters, namely chemical oxygen demand (COD), nitrate concentration (N-NO{sub 3}{sup -}), and total suspended solids (TSS). For NIR, the best results were achieved for TSS, with a relative error of 14.1% and a correlation coefficient of 0.91. The UV-visible technique gave similar results for the three parameters: an error of {proportional_to}25% and correlation coefficients of {proportional_to}0.82 for COD and TSS and 0.87 for N-NO{sub 3}{sup -}. The results obtained demonstrate that both techniques are suitable for consideration as alternative methods for monitoring and controlling wastewater treatment processes, presenting clear advantages when compared with the reference methods for wastewater treatment process qualification. (orig.)

  17. Quantitative monitoring of an activated sludge reactor using on-line UV-visible and near-infrared spectroscopy.

    Science.gov (United States)

    Sarraguça, Mafalda C; Paulo, Ana; Alves, Madalena M; Dias, Ana M A; Lopes, João A; Ferreira, Eugénio C

    2009-10-01

    The performance of an activated sludge reactor can be significantly enhanced through use of continuous and real-time process-state monitoring, which avoids the need to sample for off-line analysis and to use chemicals. Despite the complexity associated with wastewater treatment systems, spectroscopic methods coupled with chemometric tools have been shown to be powerful tools for bioprocess monitoring and control. Once implemented and optimized, these methods are fast, nondestructive, user friendly, and most importantly, they can be implemented in situ, permitting rapid inference of the process state at any moment. In this work, UV-visible and NIR spectroscopy were used to monitor an activated sludge reactor using in situ immersion probes connected to the respective analyzers by optical fibers. During the monitoring period, disturbances to the biological system were induced to test the ability of each spectroscopic method to detect the changes in the system. Calibration models based on partial least squares (PLS) regression were developed for three key process parameters, namely chemical oxygen demand (COD), nitrate concentration (N-NO(3)(-)), and total suspended solids (TSS). For NIR, the best results were achieved for TSS, with a relative error of 14.1% and a correlation coefficient of 0.91. The UV-visible technique gave similar results for the three parameters: an error of approximately 25% and correlation coefficients of approximately 0.82 for COD and TSS and 0.87 for N-NO(3)(-) . The results obtained demonstrate that both techniques are suitable for consideration as alternative methods for monitoring and controlling wastewater treatment processes, presenting clear advantages when compared with the reference methods for wastewater treatment process qualification.

  18. Photodissociation Spectroscopy of Cold Protonated Synephrine: Surprising Differences between IR-UV Hole-Burning and IR Photodissociation Spectroscopy of the O-H and N-H Modes.

    Science.gov (United States)

    Nieuwjaer, N; Desfrançois, C; Lecomte, F; Manil, B; Soorkia, S; Broquier, M; Grégoire, G

    2018-04-19

    We report the UV and IR photofragmentation spectroscopies of protonated synephrine in a cryogenically cooled Paul trap. Single (UV or IR) and double (UV-UV and IR-UV) resonance spectroscopies have been performed and compared to quantum chemistry calculations, allowing the assignment of the lowest-energy conformer with two rotamers depending on the orientation of the phenol hydroxyl (OH) group. The IR-UV hole burning spectrum exhibits the four expected vibrational modes in the 3 μm region, i.e., the phenol OH, C β -OH, and two NH 2 + stretches. The striking difference is that, among these modes, only the free phenol OH mode is active through IRPD. The protonated amino group acts as a proton donor in the internal hydrogen bond and displays large frequency shifts upon isomerization expected during the multiphoton absorption process, leading to the so-called IRMPD transparency. More interestingly, while the C β -OH is a proton acceptor group with moderate frequency shift for the different conformations, this mode is still inactive through IRPD.

  19. Measurements of the rate constant of HOsub2 + NOsub2 + Nsub2 --> HOsub2NOsub2 + Nsub2 using near-infrared wavelength-modulation spectroscopy and UV-visible absorption spectroscopy

    Science.gov (United States)

    Christensen, L. E.; Okumura, M.; Sander, S. P.; Friedl, R. R.; Miller, C. E.; Sloan, J. J.

    2004-01-01

    Rate coefficients for the reaction HO(sub 2)+ NO(sub 2) + N(sub 2) --> HO(sub 2)NO(sub 2) + N(sub 2) (reaction 1) were measured using simultaneous near-IR and UV spectroscopy from 220 to 298 K and from 45 to 200 Torr.

  20. Photochemistry of polycyclic aromatic hydrocarbons in cosmic water ice. II. Near UV/VIS spectroscopy and ionization rates

    Science.gov (United States)

    Bouwman, J.; Cuppen, H. M.; Steglich, M.; Allamandola, L. J.; Linnartz, H.

    2011-05-01

    Context. Mid-infrared emission features originating from polycyclic aromatic hydrocarbons (PAHs) are observed towards photon dominated regions in space. Towards dense clouds, however, these emission features are quenched. Observations of dense clouds show that many simple volatile molecules are frozen out on interstellar grains, forming thin layers of ice. Recently, observations have shown that more complex non-volatile species, presumably including PAHs, also freeze out and contribute to the ongoing solid-state chemistry. Aims: The study presented here aims at obtaining reaction rate data that characterize PAH photochemistry upon vacuum ultraviolet (VUV) irradiation in an interstellar H2O ice analogue to explore the potential impact of PAH:H2O ice reactions on overall interstellar ice chemistry. To this end, the experimental results are implemented in a chemical model under simple interstellar cloud conditions. Methods: Time-dependent near-UV/VIS spectroscopy on the VUV photochemistry of anthracene, pyrene, benzo[ghi]perylene and coronene containing interstellar H2O ice analogs is performed at 25 and 125 K, using an optical absorption setup. Results: Near-UV/VIS absorption spectra are presented for these four PAHs and their photoproducts including cationic species trapped in H2O ice. Oscillator strengths of the cation absorption bands are derived relative to the oscillator strength of the neutral parent PAH. The loss of the parent and growth of PAH photoproducts are measured as a function of VUV dose, yielding solid state reaction constants. The rate constants are used in an exploratory astrochemical model, to assess the importance of PAH:H2O ice photoprocessing in UV exposed interstellar environments, compared with the timescales in which PAH molecules are incorporated in interstellar ices. Conclusions: All four PAHs studied here are found to be readily ionized upon VUV photolysis when trapped in H2O ice and exhibit similar rates for ionization at astronomically

  1. Mw Spectroscopy Coupled with Ultrafast UV Laser Vaporization: {RIBOSE} Found in the Gas Phase

    Science.gov (United States)

    Cocinero, Emilio J.; Ecija, Patricia; Basterretxea, Francisco J.; Fernandez, Jose A.; Castano, Fernando; Lesarri, Alberto; Grabow, Jens-Uwe

    2012-06-01

    Sugars are aldoses or ketoses with multiple hydroxy groups which have been elusive to spectroscopic studies. Here we report a rotational study of the aldopentose ribose. According to any standard textbook aldopentoses can exhibit either linear forms, cyclic five-membered (furanose) structures or six-membered (pyranose) rings, occurring either as α- or β- anomers depending on the orientation of the hydroxy group at C-1 (anomeric carbon). β-Furanose is predominant in ribonucleosides, RNA, ATP and other biochemically relevant derivatives, but is β-furanose the native form also of free ribose? Recent condensed-phase X-ray and older NMR studies delivered conflicting results. In order to solve this question we conducted a microwave study on D-ribose that, owing to ultrafast UV laser vaporization, has become the first C-5 sugar observed with rotational resolution. The spectrum revealed six conformations of free ribose, preferentially adopting β-pyranose chairs as well as higher-energy α-pyranose forms. The method also allowed for unambiguous distinction between different orientations of the hydroxy groups, which stabilize the structures by cooperative hydrogen-bond networks. No evidence was observed of the α-/β-furanoses or linear forms found in the biochemical derivatives. i) D. Šišak, L. B. McCusker, G. Zandomeneghi, B. H. Meier, D. Bläser, R. Boese, W. B. Schweizer, R. Gylmour and J. D. Dunitz Angew. Chem. Int. Ed. 49, 4503, 2010. ii) W. Saenger Angew. Chem. Int. Ed. 49, 6487, 2010. i) M. Rudrum, and D. F. Shaw, J. Chem. Soc. 52, 1965. ii) R. U. Lemieux and J. D. Stevens Can. J. Chem. 44, 249, 1966. iii) E. Breitmaier and U. Hollstein Org. Magn. Reson. 8, 573, 1976. E. J. Cocinero, A. Lesarri, P. Écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño Angew. Chem. Int. Ed. in press: DOI: 10.1002/anie.201107973, 2012.

  2. Crystallography taken to the extreme

    Science.gov (United States)

    Dubrovinskaia, Natalia; Dubrovinsky, Leonid

    2018-06-01

    This article is a brief autobiographical account of our life in science and the path that we took in performing the research for which we were awarded the Gregori Aminoff Prize in Crystallography 2017 by the Royal Swedish Academy of Sciences. We were invited to write it by the editor-in-chief of Physica Scripta, Suzy Lidström, who charged us with the task of contributing to a series of autobiographical articles published since 2014, the International Year of Crystallography, on the lives of the Aminoff Prize winners. As this series is intended to be of particular interest to young scientists, teachers and lecturers and those researching the history of science, we tried to adhere to this purpose while writing our story. It does not pretend to be a comprehensive review either of our own scientific results or, especially, of covering the complete history of the research field of high-pressure crystallography in which we are active.

  3. Detection of olive oil adulteration by low-field NMR relaxometry and UV-Vis spectroscopy upon mixing olive oil with various edible oils

    Directory of Open Access Journals (Sweden)

    S. Ok

    2017-03-01

    Full Text Available Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF proton (1H nuclear magnetic resonance (NMR relaxometry and ultra-violet (UV visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2 curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively.

  4. Detection of olive oil adulteration by low-field NMR relaxometry and UV-Vis spectroscopy upon mixing olive oil with various edible oils

    International Nuclear Information System (INIS)

    Ok, S.

    2017-01-01

    Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF) proton (1H) nuclear magnetic resonance (NMR) relaxometry and ultra-violet (UV) visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2) curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively. [es

  5. Characterisation of PDO olive oil Chianti Classico by non-selective (UV-visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques.

    Science.gov (United States)

    Casale, M; Oliveri, P; Casolino, C; Sinelli, N; Zunin, P; Armanino, C; Forina, M; Lanteri, S

    2012-01-27

    An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV-visible (UV-vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil. Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition. In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV-vis spectra, individually and jointly, and on the fatty acid composition. Finally, PLS (partial least square) regression was applied on the UV-vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils. UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models. The non-selective information obtained from UV-vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil Chianti Classico. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Characterisation of PDO olive oil Chianti Classico by non-selective (UV-visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Casale, M., E-mail: monica@dictfa.unige.it [Universita degli Studi di Genova, Department of Chemistry and Food and Pharmaceutical Technologies, Via Brigata Salerno 13, I-16147, Genoa (Italy); Oliveri, P.; Casolino, C. [Universita degli Studi di Genova, Department of Chemistry and Food and Pharmaceutical Technologies, Via Brigata Salerno 13, I-16147, Genoa (Italy); Sinelli, N. [Universita degli Studi di Milano, Department of Food Science and Technology, Via Celoria, 2 - I-20133 Milan (Italy); Zunin, P.; Armanino, C.; Forina, M.; Lanteri, S. [Universita degli Studi di Genova, Department of Chemistry and Food and Pharmaceutical Technologies, Via Brigata Salerno 13, I-16147, Genoa (Italy)

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Characterisation of the Italian PDO extra virgin olive oil Chianti Classico. Black-Right-Pointing-Pointer Comparison between non-selective (UV-vis, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques. Black-Right-Pointing-Pointer Synergy among spectroscopic techniques, by the fusion of the respective spectra. Black-Right-Pointing-Pointer Prediction of the content of oleic and linoleic acids in the olive oils. - Abstract: An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV-visible (UV-vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil. Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition. In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV-vis spectra, individually and jointly, and on the fatty acid composition. Finally, PLS (partial least square) regression was applied on the UV-vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils. UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models. The non-selective information obtained from UV-vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil

  7. X-ray photoelectron spectroscopy investigations of band offsets in Ga0.02Zn0.98O/ZnO heterojunction for UV photodetectors

    Science.gov (United States)

    Singh, Karmvir; Rawal, Ishpal; Punia, Rajesh; Dhar, Rakesh

    2017-10-01

    Here, we report the valence and conduction band offset measurements in pure ZnO and the Ga0.02Zn0.98O/ZnO heterojunction by X-Ray photoelectron spectroscopy studies for UV photodetector applications. For detailed investigations on the band offsets and UV photodetection behavior of Ga0.02Zn0.98O/ZnO heterostructures, thin films of pristine ZnO, Ga-doped ZnO (Ga0.02Zn0.98O), and heterostructures of Ga-doped ZnO with ZnO (Ga0.02Zn0.98O/ZnO) were deposited using a pulsed laser deposition technique. The deposited thin films were characterized by X-ray diffraction, atomic force microscopy, and UV-Vis spectroscopy. X-ray photoelectron spectroscopy studies were carried out on all the thin films for the investigation of valence and conduction band offsets. The valence band was found to be shifted by 0.28 eV, while the conduction band has a shifting of -0.272 eV in the Ga0.02Zn0.98O/ZnO heterojunction as compared to pristine ZnO thin films. All the three samples were analyzed for photoconduction behavior under UVA light of the intensity of 3.3 mW/cm2, and it was observed that the photoresponse of pristine ZnO (19.75%) was found to increase with 2 wt. % doping of Ga (22.62%) and heterostructured thin films (29.10%). The mechanism of UV photodetection in the deposited samples has been discussed in detail, and the interaction of chemisorbed oxygen on the ZnO surface with holes generated by UV light exposure has been the observed mechanism for the change in electrical conductivity responsible for UV photoresponse on the present deposited ZnO films.

  8. C-shaped diastereomers containing cofacial thiophene-substituted quinoxaline rings: synthesis, photophysical properties, and X-ray crystallography.

    Science.gov (United States)

    DeBlase, Catherine R; Finke, Ryan T; Porras, Jonathan A; Tanski, Joseph M; Nadeau, Jocelyn M

    2014-05-16

    Synthesis and characterization of two diastereomeric C-shaped molecules containing cofacial thiophene-substituted quinoxaline rings are described. A previously known bis-α-diketone was condensed with an excess of 4-bromo-1,2-diaminobenzene in the presence of zinc acetate to give a mixture of two C-shaped diastereomers with cofacial bromine-substituted quinoxaline rings. After chromatographic separation, thiophene rings were installed by a microwave-assisted Suzuki coupling reaction, resulting in highly emissive diastereomeric compounds that were studied by UV-vis, fluorescence, and NMR spectroscopy, as well as X-ray crystallography. The unique symmetry of each diastereomer was confirmed by NMR spectroscopy. NMR data indicated that the syn isomer has restricted rotation about the bond connecting the thiophene and quinoxaline rings, which was also observed in the solid state. The spectroscopic properties of the C-shaped diastereomers were compared to a model compound containing only a single thiophene-substituted quinoxaline ring. Ground state intramolecular π-π interactions in solution were detected by NMR and UV-vis spectroscopy. Red-shifted emission bands, band broadening, and large Stokes shifts were observed, which collectively suggest excited state π-π interactions that produce excimer-like emissions, as well as a remarkable positive emission solvatochromism, indicating charge-transfer character in the excited state.

  9. Photochemistry of PAHs in cosmic water ice. The effect of concentration on UV-VIS spectroscopy and ionization efficiency

    Science.gov (United States)

    Cuylle, Steven H.; Allamandola, Louis J.; Linnartz, Harold

    2014-02-01

    Context. Observations and models show that polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium. Like other molecules in dense clouds, PAHs accrete onto interstellar dust grains, where they are embedded in an ice matrix dominated by water. In the laboratory, mixed molecular ices (not containing PAHs) have been extensively studied using Fourier transform infrared absorption spectroscopy. Experiments including PAHs in ices have started, however, the concentrations used are typically much higher than the concentrations expected for interstellar ices. Optical spectroscopy offers a sensitive alternative. Aims: We report an experimental study of the effect PAH concentration has on the electronic spectra and the vacuum UV (VUV) driven processes of PAHs in water-rich ices. The goal is to apply the outcome to cosmic ices. Methods: Optical spectroscopic studies allow us to obtain in-situ and quasi real-time electronic solid state spectra of two prototypical PAHs (pyrene and coronene) embedded in water ice under VUV photoprocessing. The study is carried out on PAH:H2O concentrations in the range of 1:30 000 to pure PAH, covering the temperature range from 12 to 125 K. Results: PAH concentration strongly influences the efficiency of PAH cation formation. At low concentrations, ionization efficiencies are over 60% dropping to about 15% at 1:1000. Increasing the PAH concentration reveals spectral broadening in neutral and cation PAH spectra attributed to PAH clustering inside the ice. At the PAH concentrations expected for interstellar ices, some 10 to 20% may be present as cations. The presence of PAHs in neutral and ion form will add distinctive absorption bands to cosmic ice optical spectra and this may serve as a tool to determine PAH concentrations.

  10. Wastewater Biosolid Composting Optimization Based on UV-VNIR Spectroscopy Monitoring.

    Science.gov (United States)

    Temporal-Lara, Beatriz; Melendez-Pastor, Ignacio; Gómez, Ignacio; Navarro-Pedreño, Jose

    2016-11-15

    Conventional wastewater treatment generates large amounts of organic matter-rich sludge that requires adequate treatment to avoid public health and environmental problems. The mixture of wastewater sludge and some bulking agents produces a biosolid to be composted at adequate composting facilities. The composting process is chemically and microbiologically complex and requires an adequate aeration of the biosolid (e.g., with a turner machine) for proper maturation of the compost. Adequate (near) real-time monitoring of the compost maturity process is highly difficult and the operation of composting facilities is not as automatized as other industrial processes. Spectroscopic analysis of compost samples has been successfully employed for compost maturity assessment but the preparation of the solid compost samples is difficult and time-consuming. This manuscript presents a methodology based on a combination of a less time-consuming compost sample preparation and ultraviolet, visible and short-wave near-infrared spectroscopy. Spectroscopic measurements were performed with liquid compost extract instead of solid compost samples. Partial least square (PLS) models were developed to quantify chemical fractions commonly employed for compost maturity assessment. Effective regression models were obtained for total organic matter (residual predictive deviation-RPD = 2.68), humification ratio (RPD = 2.23), total exchangeable carbon (RPD = 2.07) and total organic carbon (RPD = 1.66) with a modular and cost-effective visible and near infrared (VNIR) spectroradiometer. This combination of a less time-consuming compost sample preparation with a versatile sensor system provides an easy-to-implement, efficient and cost-effective protocol for compost maturity assessment and near-real-time monitoring.

  11. Wastewater Biosolid Composting Optimization Based on UV-VNIR Spectroscopy Monitoring

    Directory of Open Access Journals (Sweden)

    Beatriz Temporal-Lara

    2016-11-01

    Full Text Available Conventional wastewater treatment generates large amounts of organic matter–rich sludge that requires adequate treatment to avoid public health and environmental problems. The mixture of wastewater sludge and some bulking agents produces a biosolid to be composted at adequate composting facilities. The composting process is chemically and microbiologically complex and requires an adequate aeration of the biosolid (e.g., with a turner machine for proper maturation of the compost. Adequate (near real-time monitoring of the compost maturity process is highly difficult and the operation of composting facilities is not as automatized as other industrial processes. Spectroscopic analysis of compost samples has been successfully employed for compost maturity assessment but the preparation of the solid compost samples is difficult and time-consuming. This manuscript presents a methodology based on a combination of a less time-consuming compost sample preparation and ultraviolet, visible and short-wave near-infrared spectroscopy. Spectroscopic measurements were performed with liquid compost extract instead of solid compost samples. Partial least square (PLS models were developed to quantify chemical fractions commonly employed for compost maturity assessment. Effective regression models were obtained for total organic matter (residual predictive deviation—RPD = 2.68, humification ratio (RPD = 2.23, total exchangeable carbon (RPD = 2.07 and total organic carbon (RPD = 1.66 with a modular and cost-effective visible and near infrared (VNIR spectroradiometer. This combination of a less time-consuming compost sample preparation with a versatile sensor system provides an easy-to-implement, efficient and cost-effective protocol for compost maturity assessment and near-real-time monitoring.

  12. In-line UV spectroscopy for the quantification of low-dose active ingredients during the manufacturing of pharmaceutical semi-solid and liquid formulations.

    Science.gov (United States)

    Bostijn, N; Hellings, M; Van Der Veen, M; Vervaet, C; De Beer, T

    2018-07-12

    UltraViolet (UV) spectroscopy was evaluated as an innovative Process Analytical Technology (PAT) - tool for the in-line and real-time quantitative determination of low-dosed active pharmaceutical ingredients (APIs) in a semi-solid (gel) and a liquid (suspension) pharmaceutical formulation during their batch production process. The performance of this new PAT-tool (i.e., UV spectroscopy) was compared with an already more established PAT-method based on Raman spectroscopy. In-line UV measurements were carried out with an immersion probe while for the Raman measurements a non-contact PhAT probe was used. For both studied formulations, an in-line API quantification model was developed and validated per spectroscopic technique. The known API concentrations (Y) were correlated with the corresponding in-line collected preprocessed spectra (X) through a Partial Least Squares (PLS) regression. Each developed quantification method was validated by calculating the accuracy profile on the basis of the validation experiments. Furthermore, the measurement uncertainty was determined based on the data generated for the determination of the accuracy profiles. From the accuracy profile of the UV- and Raman-based quantification method for the gel, it was concluded that at the target API concentration of 2% (w/w), 95 out of 100 future routine measurements given by the Raman method will not deviate more than 10% (relative error) from the true API concentration, whereas for the UV method the acceptance limits of 10% were exceeded. For the liquid formulation, the Raman method was not able to quantify the API in the low-dosed suspension (0.09% (w/w) API). In contrast, the in-line UV method was able to adequately quantify the API in the suspension. This study demonstrated that UV spectroscopy can be adopted as a novel in-line PAT-technique for low-dose quantification purposes in pharmaceutical processes. Important is that none of the two spectroscopic techniques was superior to the other

  13. Macromolecular neutron crystallography at the Protein Crystallography Station (PCS)

    OpenAIRE

    Kovalevsky, Andrey; Fisher, Zoe; Johnson, Hannah; Mustyakimov, Marat; Waltman, Mary Jo; Langan, Paul

    2010-01-01

    The Protein Crystallography Station user facility at Los Alamos National Laboratory not only offers open access to a high-performance neutron beamline, but also actively supports and develops new methods in protein expression, deuteration, purification, robotic crystallization and the synthesis of substrates with stable isotopes and provides assistance with data-reduction and structure-refinement software and comprehensive neutron structure analysis.

  14. Synthesis and Study of Optical Properties of Graphene/TiO2 Composites Using UV-VIS Spectroscopy

    Science.gov (United States)

    Rathod, P. B.; Waghuley, S. A.

    2016-09-01

    Graphene and TiO2 were synthesized using electrochemical exfoliation and co-precipitation methods, respectively. An ex situ approach was adopted for the graphene/TiO2 composites. The conformation of graphene in the TiO2 samples was examined through X-ray diffraction. Optical properties of the as-synthesised composites such as optical absorption, extinction coefficient, refractive index, real dielectric constant, imaginary dielectric constant, dissipation factor, and optical conductivity were measured using UV-Vis spectroscopy. The varying concentration of graphene in TiO2 affects the optical properties which appear different for 10 wt.% as compared to 5 wt.% graphene/ TiO2 composite. The composites exhibit an absorption peak at 300 nm with a decrease in band gap for 10 wt.% as compared to 5 wt.% graphene/TiO2 composite. The maximum optical conductivity for the graphene/TiO2 composite of 10 wt.% was found to be 1.86·10-2 Ω-1·m-1 at 300 nm.

  15. Artificial nose, NIR and UV-visible spectroscopy for the characterisation of the PDO Chianti Classico olive oil.

    Science.gov (United States)

    Forina, M; Oliveri, P; Bagnasco, L; Simonetti, R; Casolino, M C; Nizzi Grifi, F; Casale, M

    2015-11-01

    An authentication study of the Italian PDO (Protected Designation of Origin) olive oil Chianti Classico, based on artificial nose, near-infrared and UV-visible spectroscopy, with a set of samples representative of the whole Chianti Classico production area and a considerable number of samples from other Italian PDO regions was performed. The signals provided by the three analytical techniques were used both individually and jointly, after fusion of the respective variables, in order to build a model for the Chianti Classico PDO olive oil. Different signal pre-treatments were performed in order to investigate their importance and their effects in enhancing and extracting information from experimental data, correcting backgrounds or removing baseline variations. Stepwise-Linear Discriminant Analysis (STEP-LDA) was used as a feature selection technique and, afterward, Linear Discriminant Analysis (LDA) and the class-modelling technique Quadratic Discriminant Analysis-UNEQual dispersed classes (QDA-UNEQ) were applied to sub-sets of selected variables, in order to obtain efficient models capable of characterising the extra virgin olive oils produced in the Chianti Classico PDO area. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. UV-Vis spectroscopy combined with chemometric study on the interactions of three dietary flavonoids with copper ions.

    Science.gov (United States)

    Zhang, Liangliang; Liu, Yuchen; Wang, Yongmei; Xu, Man; Hu, Xinyu

    2018-10-15

    The complex formation between a copper ion and the dietary flavonoid quercetin (QU) and its two glycosides hyperin (HY) and rutin (RU) was studied by the combined use of spectroscopic measurement and the chemometric method. The spectral changes of pH titration revealed two successively formed deprotonated species of QU: the first formed species was proposed to be the 3-hydroxyl group deprotonated QU, and the second was the quinone form QU, which was formed by oxidation after the hydroxyl groups in the B-ring were deprotonated at high pH values. Similar results were obtained for HY and RU with two deprotonated species forming at high pH values. UV/visible spectroscopy showed successive formation of CuL 2 and CuL species of QU at pH 6.0, while only Cu 2 L was formed for HY and RU at this pH. Glycoside moieties in the C-ring of flavonoids decrease the conditional associated constants between flavonoids and Cu 2+ . Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. A kinetic study on the formation of poly(4 aminodiphenylamine)/copper nanocomposite using UV-visible spectroscopy.

    Science.gov (United States)

    Starlet Thanjam, I; Francklin Philips, M; Manisankar, P; Lee, Kwang-Pill; Gopalan, A

    2013-12-01

    The course of the reaction between copper sulfate (CuSO4) and 4-aminodiphenylamine (4ADPA) was monitored by UV-visible spectroscopy in p-toluene sulfonic acid (p-TSA). Formation of poly(4-aminodiphenylamine)/copper nanoparticle composite (P4ADPA/CuNC) was witnessed through the steady increase in absorbance at 410, 580 and >700 nm. The absorbance at 410 nm as well as >700 nm are correlated to the amount of P4ADPA/CuNC formation and was subsequently used to determine the rate of formation of P4ADPA/CuNC (RP4ADPA/CuNC) at any time during the course of the reaction. RP4ADPA/CuNC shows a first-order dependence on [4ADPA] and a half-order dependence on [CuSO4]. A kinetic rate expression was established between RP4ADPA/CuNC and experimental parameters such as [4ADPA] and [CuSO4]. The rate constant for the formation of P4ADPA/CuNC was 8.98 × 10(-3) mol(-0.5) l(0.5) s(-1). Field emission scanning electron and transmission electron micrographs revealed that the morphology of the P4ADPA/CuNC was influenced by the reaction conditions. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Kinetic study on bonding reaction of gelatin with CdS nanopaticles by UV-visible spectroscopy.

    Science.gov (United States)

    Tang, Shihua; Wang, Baiyang; Li, Youqun

    2015-04-15

    The chemical kinetics on gelatin-CdS direct conjugates has been systematically investigated as a function of different temperature and reactant concentration (i.e. Cd(2+), S(2-) and gelatin) by UV-visible spectroscopy, for the first time. The nonlinear fitting and the differential method were used to calculate the initial rate based on the absorbance-time data. A double logarithmic linear equation for calculating the rate constant (k) and the reaction order (n) was introduced. The reaction kinetic parameters (n, k, Ea, and Z) and activation thermodynamic parameters (ΔG(≠), ΔH(≠), and ΔS(≠)) were obtained from variable temperature kinetic studies. The overall rate equation allowing evaluation of conditions that provide required reaction rate could be expressed as: r = 1.11 × 10(8) exp(-4971/T)[Cd(2+)][gelatin](0.6)[S(2-)](0.6) (M/S) The calculated values of the reaction rate are well coincide with the experimental results. A suitable kinetic model is also proposed. This work will provide guidance for the rational design of gelatin-directed syntheses of metal sulfide materials, and help to understand the biological effects of nanoparticles at the molecular level. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Rapid Method for the Determination of 5-Hydroxymethylfurfural and Levulinic Acid Using a Double-Wavelength UV Spectroscopy

    Directory of Open Access Journals (Sweden)

    Junhua Zhang

    2013-01-01

    Full Text Available This study reports on a rapid method for the determination of levulinic acid (LA and 5-hydroxymethylfurfural (HMF in acid hydrolyze system of glucose based on UV spectroscopy. It was found that HMF and LA have a maximum absorption at the wavelengths of 284 nm and 266 nm, respectively, in a water medium, and the absorptions of HMF and LA at 284 nm and 266 nm follow Beer’s law very well. However, it was found that a major spectral interference species will arise in the quantification of HMF and LA; nonetheless, this interference can be eliminated through the absorption treatment of charcoal. Therefore, both HMF and LA can be quantified with a double-wavelength technique. The repeatability of the method had a relative standard deviation of less than 4.47% for HMF and 2.25% for LA; the limit of quantification (LOQ was 0.017 mmol/L for HMF and 4.68 mmol/L for LA, and the recovery ranged from 88% to 116% for HMF and from 94% to 105% for LA. The present method is simple, rapid, and accurate. It is suitable to use in the research of the preparation of HMF and LA in biorefinery area.

  20. The electrochemical oxidation of sulfite on gold: UV-Vis reflectance spectroscopy at a rotating disk electrode

    International Nuclear Information System (INIS)

    Tolmachev, Yuriy V.; Scherson, Daniel A.

    2004-01-01

    Certain aspects of the electrochemical oxidation of sulfite in buffered, mildly acidic aqueous solutions (pH 5.23) have been examined using in situ near normal incidence UV-Vis reflectance spectroscopy (NNI-UVRS) at a Au rotating disk electrode (RDE). The dependence of the limiting current, i lim , on the rotation rate of the RDE was found to display classical Levich behavior up to potentials well within the range in which Au forms a surface oxide in the neat (sulfite-free) supporting electrolyte. However, simultaneous in situ NNI-UVRS measurements performed at λ=500 nm during sulfite oxidation failed to show any evidence for the presence of oxide on the Au surface within that entire potential range. Polarization of the Au RDE at more positive potentials led to a sudden drop in i lim , ca. an order of magnitude, which correlated with an abrupt decrease in the intensity of the reflected light, consistent with formation of (one or more forms of) Au oxide on the surface. On the basis of these and other observations a model has been proposed in which sulfite reacts chemically with adsorbed oxygen on the surface (oxygen atom transfer) in the region that precedes partial inhibition. As the potential is increased, adsorbed oxygen undergoes Au-O place exchange forming two-dimensional nuclei on the surface, which undergo rapid (autocatalytic) growth, covering an area large enough to block significantly sulfite oxidation

  1. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers

    Science.gov (United States)

    Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Harrison, J. A.; Steiner, B.; Saykally, R. J.

    1998-01-01

    Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

  2. Applicability of UV laser-induced solid-state fluorescence spectroscopy for characterization of solid dosage forms.

    Science.gov (United States)

    Woltmann, Eva; Meyer, Hans; Weigel, Diana; Pritzke, Heinz; Posch, Tjorben N; Kler, Pablo A; Schürmann, Klaus; Roscher, Jörg; Huhn, Carolin

    2014-10-01

    High production output of solid pharmaceutical formulations requires fast methods to ensure their quality. Likewise, fast analytical procedures are required in forensic sciences, for example at customs, to substantiate an initial suspicion. We here present the design and the optimization of an instrumental setup for rapid and non-invasive characterization of tablets by laser-induced fluorescence spectroscopy (with a UV-laser (λ ex = 266 nm) as excitation source) in reflection geometry. The setup was first validated with regard to repeatability, bleaching phenomena, and sensitivity. The effect on the spectra by the physical and chemical properties of the samples, e.g. their hardness, homogeneity, chemical composition, and granule grain size of the uncompressed material, using a series of tablets, manufactured in accordance with design of experiments, was investigated. Investigation of tablets with regard to homogeneity, especially, is extremely important in pharmaceutical production processes. We demonstrate that multiplicative scatter correction is an appropriate tool for data preprocessing of fluorescence spectra. Tablets with different physical and chemical characteristics can be discriminated well from their fluorescence spectra by subjecting the results to principal component analysis.

  3. Crystallography across the Sciences 2

    NARCIS (Netherlands)

    Schenk, H.

    2008-01-01

    This second commemorative compilation from the IUCr contains 24 invited articles, all refereed, from some of today's most eminent crystallographers. The articles describe state-of-the-art research in which crystallography has played a major role, and are intended to be attractive for a broad

  4. The Cambridge crystallography subroutine library

    International Nuclear Information System (INIS)

    Brown, P.J.; Matthewman, J.C.

    1981-06-01

    This manual is an amalgamation of the original Cambridge Crystallography Subroutine Library Mark II manual and its supplement No I. The original Mark II system, a set of FORTRAN Subroutines which can be used for standard crystallographic calculations, has been extended to include facilities for conventional least squares refinement. Several new routines have also been added. (U.K.)

  5. Application of nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, UV-Visible spectroscopy and kinetic modeling for elucidation of adsorption chemistry in uptake of tetracycline by zeolite beta.

    Science.gov (United States)

    Kang, Jin; Liu, Huijuan; Zheng, Yu-Ming; Qu, Jiuhui; Chen, J Paul

    2011-02-01

    Extensive usage of tetracycline has resulted in its contamination in surface water and groundwater. The adsorption of tetracycline on zeolite beta was systematically investigated for the decontamination of the antibiotic polluted water in this study. Ninety percent of uptake by the zeolite beta occured in 0.25h, and the adsorption equilibrium was obtained within 3h, which was well described by an intraparticle diffusion model. The adsorption generally increased when pH was increased from 4.0 to 5.0, and then decreased significantly as the pH was further increased, which was caused by the pH-dependent speciation of tetracycline and surface charge of zeolite beta. Both Freundlich and Langmuir equations well described the adsorption isotherm. A thermodynamic analysis showed that the sorption process was spontaneous and endothermic. Aluminum atoms in the zeolite played a crucial role in the uptake; the adsorption increased with the increasing aluminum content in zeolite. The UV-Visible spectroscopy study showed that the spectra of tetracycline changed upon the interaction with zeolite beta, which could be ascribed to the formation of complexes of tetracycline and aluminum atoms in the zeolite surface. Nuclear magnetic resonance spectroscopy study further confirmed the participation of Al in the tetracycline adsorption. Fourier transform infrared spectroscopy studies showed that the amino functional groups in tetracycline were involved in the complexation with the zeolite surface. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Shedding Light on the Oxygen Reduction Reaction Mechanism in Ether-Based Electrolyte Solutions: A Study Using Operando UV-Vis Spectroscopy.

    Science.gov (United States)

    Hirshberg, Daniel; Sharon, Daniel; Afri, Michal; Lavi, Ronit; Frimer, Aryeh A; Metoki, Noa; Eliaz, Noam; Kwak, Won-Jin; Sun, Yang-Kook; Aurbach, Doron

    2018-04-04

    Using UV-vis spectroscopy in conjunction with various electrochemical techniques, we have developed a new effective operando methodology for investigating the oxygen reduction reactions (ORRs) and their mechanisms in nonaqueous solutions. We can follow the in situ formation and presence of superoxide moieties during ORR as a function of solvent, cations, anions, and additives in the solution. Thus, using operando UV-vis spectroscopy, we found evidence for the formation of superoxide radical anions during oxygen reduction in LiTFSI/diglyme electrolyte solutions. Nitro blue tetrazolium (NBT) was used to indicate the presence of superoxide moieties based on its unique spectral response. Indeed, the spectral response of NBT containing solutions undergoing ORR could provide a direct indication for the level of association of the Li cations with the electrolyte anions.

  7. Use of UV-vis-NIR spectroscopy to monitor label-free interaction between molecular recognition elements and erythropoietin on a gold-coated polycarbonate platform.

    Science.gov (United States)

    Citartan, Marimuthu; Gopinath, Subash C B; Tominaga, Junji; Chen, Yeng; Tang, Thean-Hock

    2014-08-01

    Label-free-based detection is pivotal for real-time monitoring of biomolecular interactions and to eliminate the need for labeling with tags that can occupy important binding sites of biomolecules. One simplest form of label-free-based detection is ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, which measure changes in reflectivity as a means to monitor immobilization and interaction of biomolecules with their corresponding partners. In biosensor development, the platform used for the biomolecular interaction should be suitable for different molecular recognition elements. In this study, gold (Au)-coated polycarbonate was used as a platform and as a proof-of-concept, erythropoietin (EPO), a doping substance widely abused by the athletes was used as the target. The interaction of EPO with its corresponding molecular recognition elements (anti-EPO monoclonal antibody and anti-EPO DNA aptamer) is monitored by UV-vis-NIR spectroscopy. Prior to this, to show that UV-vis-NIR spectroscopy is a suitable method for measuring biomolecular interaction, the interaction between biotin and streptavidin was demonstrated via this strategy and reflectivity of this interaction decreased by 25%. Subsequent to this, interaction of the EPO with anti-EPO monoclonal antibody and anti-EPO DNA aptamer resulted in the decrease of reflectivity by 5% and 10%, respectively. The results indicated that Au-coated polycarbonate could be an ideal biosensor platform for monitoring biomolecular interactions using UV-vis-NIR spectroscopy. A smaller version of the Au-coated polycarbonate substrates can be derived from the recent set-up, to be applied towards detecting EPO abuse among atheletes. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. UV-visible-DAD and 1H-NMR spectroscopy data fusion for studying the photodegradation process of azo-dyes using MCR-ALS.

    Science.gov (United States)

    Fernández, Cristina; Pilar Callao, M; Larrechi, M Soledad

    2013-12-15

    The photodegradation process of three azo-dyes - Acid Orange 61, Acid Red 97 and Acid Brown 425 - was monitored simultaneously by ultraviolet-visible spectroscopy with diode array detector (UV-vis-DAD) and (1)H-nuclear magnetic resonance ((1)H-NMR). Multivariate curve resolution-alternating least squares (MCR-ALS) was applied to obtain the concentration and spectral profile of the chemical compounds involved in the process. The analysis of the H-NMR data suggests there are more intermediate compounds than those obtained with the UV-vis-DAD data. The fusion of UV-vis-DAD and the (1)H-NMR signal before the multivariate analysis provides better results than when only one of the two detector signals was used. It was concluded that three degradation products were present in the medium when the three azo-dyes had practically degraded. This study is the first application of UV-vis-DAD and (1)H-NMR spectroscopy data fusion in this field and illustrates its potential as a quick method for evaluating the evolution of the azo-dye photodegradation process. © 2013 Elsevier B.V. All rights reserved.

  9. A novel combined approach of diffuse reflectance UV-Vis-NIR spectroscopy and multivariate analysis for non-destructive examination of blue ballpoint pen inks in forensic application.

    Science.gov (United States)

    Kumar, Raj; Sharma, Vishal

    2017-03-15

    The present research is focused on the analysis of writing inks using destructive UV-Vis spectroscopy (dissolution of ink by the solvent) and non-destructive diffuse reflectance UV-Vis-NIR spectroscopy along with Chemometrics. Fifty seven samples of blue ballpoint pen inks were analyzed under optimum conditions to determine the differences in spectral features of inks among same and different manufacturers. Normalization was performed on the spectroscopic data before chemometric analysis. Principal Component Analysis (PCA) and K-mean cluster analysis were used on the data to ascertain whether the blue ballpoint pen inks could be differentiated by their UV-Vis/UV-Vis NIR spectra. The discriminating power is calculated by qualitative analysis by the visual comparison of the spectra (absorbance peaks), produced by the destructive and non-destructive methods. In the latter two methods, the pairwise comparison is made by incorporating the clustering method. It is found that chemometric method provides better discriminating power (98.72% and 99.46%, in destructive and non-destructive, respectively) in comparison to the qualitative analysis (69.67%). Copyright © 2016 Elsevier B.V. All rights reserved.

  10. KECK SPECTROSCOPY OF LYMAN-BREAK GALAXIES AND ITS IMPLICATIONS FOR THE UV-CONTINUUM AND Lyα LUMINOSITY FUNCTIONS AT z > 6

    International Nuclear Information System (INIS)

    Jiang Linhua; Egami, Eiichi; Walth, Gregory; Kashikawa, Nobunari; Matsuda, Yuichi; Shimasaku, Kazuhiro; Nagao, Tohru; Ota, Kazuaki; Ouchi, Masami

    2011-01-01

    We present Keck spectroscopic observations of z > 6 Lyman-break galaxy (LBG) candidates in the Subaru Deep Field (SDF). The candidates were selected as i'-dropout objects down to z' = 27 AB magnitudes from an ultra-deep SDF z'-band image. With the Keck spectroscopy we identified 19 LBGs with prominent Lyα emission lines at 6 ≤ z ≤ 6.4. The median value of the Lyα rest-frame equivalent widths (EWs) is ∼50 Å, with four EWs >100 Å. This well-defined spectroscopic sample spans a UV-continuum luminosity range of –21.8 ≤ M UV ≤ –19.5 (0.6 ∼ 5 L* UV ) and a Lyα luminosity range of (0.3-3) × 10 43 erg s –1 (0.3-3 L* Lyα ). We derive the UV and Lyα luminosity functions (LFs) from our sample at (z) ∼ 6.2 after we correct for sample incompleteness. We find that our measurement of the UV LF is consistent with the results of previous studies based on photometric LBG samples at 5 6.

  11. Combination of UV-vis spectroscopy and chemometrics to understand protein-nanomaterial conjugate: a case study on human serum albumin and gold nanoparticles.

    Science.gov (United States)

    Wang, Yong; Ni, Yongnian

    2014-02-01

    Study of the interactions between proteins and nanomaterials is of great importance for understanding of protein nanoconjugate. In this work, we choose human serum albumin (HSA) and citrate-capped gold nanoparticles (AuNPs) as a model of protein and nanomaterial, and combine UV-vis spectroscopy with multivariate curve resolution by an alternating least squares (MCR-ALS) algorithm to present a new and efficient method for comparatively comprehensive study of evolution of protein nanoconjugate. UV-vis spectroscopy coupled with MCR-ALS allows qualitative and quantitative extraction of the distribution diagrams, spectra and kinetic profiles of absorbing pure species (AuNPs and AuNPs-HSA conjugate are herein identified) and undetectable species (HSA) from spectral data. The response profiles recovered are converted into the desired thermodynamic, kinetic and structural parameters describing the protein nanoconjugate evolution. Analysis of these parameters for the system gives evidence that HSA molecules are very likely to be attached to AuNPs surface predominantly as a flat monolayer to form a stable AuNPs-HSA conjugate with a core-shell structure, and the binding process takes place mainly through electrostatic and hydrogen-bond interactions between the positively amino acid residues of HSA and the negatively carboxyl group of citrate on AuNPs surface. The results obtained are verified by transmission electron microscopy, zeta potential, circular dichroism spectroscopy and Fourier transform infrared spectroscopy, showing the potential of UV-vis spectroscopy for study of evolution of protein nanoconjugate. In parallel, concentration evolutions of pure species resolved by MCR-ALS are used to construct a sensitive spectroscopic biosensor for HSA with a linear range from 1.8 nM to 28.1 nM and a detection limit of 0.8 nM. © 2013 Published by Elsevier B.V.

  12. The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy.

    Science.gov (United States)

    Armendariz, Veronica; Parsons, Jason G; Lopez, Martha L; Peralta-Videa, Jose R; Jose-Yacaman, Miguel; Gardea-Torresdey, Jorge L

    2009-03-11

    Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

  13. The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy

    International Nuclear Information System (INIS)

    Armendariz, Veronica; Parsons, Jason G; Lopez, Martha L; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L; Jose-Yacaman, Miguel

    2009-01-01

    Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

  14. Nanoflow electrospinning serial femtosecond crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Sierra, Raymond G.; Laksmono, Hartawan [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Kern, Jan [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Tran, Rosalie; Hattne, Johan [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Alonso-Mori, Roberto [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Lassalle-Kaiser, Benedikt [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Glöckner, Carina; Hellmich, Julia [Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin (Germany); Schafer, Donald W. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Echols, Nathaniel; Gildea, Richard J.; Grosse-Kunstleve, Ralf W. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Sellberg, Jonas [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Stockholm University, S-106 91 Stockholm (Sweden); McQueen, Trevor A. [Stanford University, Stanford, CA 94025 (United States); Fry, Alan R.; Messerschmidt, Marc M.; Miahnahri, Alan; Seibert, M. Marvin; Hampton, Christina Y.; Starodub, Dmitri; Loh, N. Duane; Sokaras, Dimosthenis; Weng, Tsu-Chien [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Zwart, Petrus H. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Glatzel, Pieter [European Synchrotron Radiation Facility, Grenoble (France); Milathianaki, Despina; White, William E. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Adams, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Williams, Garth J.; Boutet, Sébastien [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Zouni, Athina [Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin (Germany); Messinger, Johannes [Umeå Universitet, Umeå (Sweden); Sauter, Nicholas K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Bergmann, Uwe [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Yano, Junko; Yachandra, Vittal K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Bogan, Michael J., E-mail: mbogan@slac.stanford.edu [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

    2012-11-01

    A low flow rate liquid microjet method for delivery of hydrated protein crystals to X-ray lasers is presented. Linac Coherent Light Source data demonstrates serial femtosecond protein crystallography with micrograms, a reduction of sample consumption by orders of magnitude. An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14–3.1 µl min{sup −1} to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed at 0.17 µl min{sup −1} and diffracted to beyond 4 Å resolution, producing 14 000 indexable diffraction patterns, or four per second, from 140 µg of protein. Nanoflow electrospinning extends SFX to biological samples that necessitate minimal sample consumption.

  15. Nanoflow electrospinning serial femtosecond crystallography

    International Nuclear Information System (INIS)

    Sierra, Raymond G.; Laksmono, Hartawan; Kern, Jan; Tran, Rosalie; Hattne, Johan; Alonso-Mori, Roberto; Lassalle-Kaiser, Benedikt; Glöckner, Carina; Hellmich, Julia; Schafer, Donald W.; Echols, Nathaniel; Gildea, Richard J.; Grosse-Kunstleve, Ralf W.; Sellberg, Jonas; McQueen, Trevor A.; Fry, Alan R.; Messerschmidt, Marc M.; Miahnahri, Alan; Seibert, M. Marvin; Hampton, Christina Y.; Starodub, Dmitri; Loh, N. Duane; Sokaras, Dimosthenis; Weng, Tsu-Chien; Zwart, Petrus H.; Glatzel, Pieter; Milathianaki, Despina; White, William E.; Adams, Paul D.; Williams, Garth J.; Boutet, Sébastien; Zouni, Athina; Messinger, Johannes; Sauter, Nicholas K.; Bergmann, Uwe; Yano, Junko; Yachandra, Vittal K.; Bogan, Michael J.

    2012-01-01

    A low flow rate liquid microjet method for delivery of hydrated protein crystals to X-ray lasers is presented. Linac Coherent Light Source data demonstrates serial femtosecond protein crystallography with micrograms, a reduction of sample consumption by orders of magnitude. An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14–3.1 µl min −1 to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed at 0.17 µl min −1 and diffracted to beyond 4 Å resolution, producing 14 000 indexable diffraction patterns, or four per second, from 140 µg of protein. Nanoflow electrospinning extends SFX to biological samples that necessitate minimal sample consumption

  16. uv dye lasers

    International Nuclear Information System (INIS)

    Abakumov, G.A.; Fadeev, V.V.; Khokhlov, R.V.; Simonov, A.P.

    1975-01-01

    The most important property of visible dye lasers, that is, continuous wavelength tuning, stimulated the search for dyes capable to lase in uv. They were found in 1968. Now the need for tunable uv lasers for applications in spectroscopy, photochemistry, isotope separation, remote air and sea probing, etc. is clearly seen. A review of some recent advances in uv dye lasers is reviewed

  17. Direct methods in protein crystallography.

    Science.gov (United States)

    Karle, J

    1989-11-01

    It is pointed out that the 'direct methods' of phase determination for small-structure crystallography do not have immediate applicability to macromolecular structures. The term 'direct methods in macromolecular crystallography' is suggested to categorize a spectrum of approaches to macromolecular structure determination in which the analyses are characterized by the use of two-phase and higher-order-phase invariants. The evaluation of the invariants is generally obtained by the use of heavy-atom techniques. The results of a number of the more recent algebraic and probabilistic studies involving isomorphous replacement and anomalous dispersion thus become valid subjects for discussion here. These studies are described and suggestions are also presented concerning future applicability. Additional discussion concerns the special techniques of filtering, the use of non-crystallographic symmetry, some features of maximum entropy and attempts to apply phase-determining formulas to the refinement of macromolecular structure. It is noted that, in addition to the continuing remarkable progress in macromolecular crystallography based on the traditional applications of isomorphous replacement and anomalous dispersion, recent valuable advances have been made in the application of non-crystallographic symmetry, in particular, to virus structures and in applications of filtering. Good progress has also been reported in the application of exact linear algebra to multiple-wavelength anomalous-dispersion investigations of structures containing anomalous scatterers of only moderate scattering power.

  18. KECK SPECTROSCOPY OF LYMAN-BREAK GALAXIES AND ITS IMPLICATIONS FOR THE UV-CONTINUUM AND Ly{alpha} LUMINOSITY FUNCTIONS AT z > 6

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Linhua; Egami, Eiichi; Walth, Gregory [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Kashikawa, Nobunari [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Matsuda, Yuichi [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Shimasaku, Kazuhiro [Department of Astronomy, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Nagao, Tohru [Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan); Ota, Kazuaki [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Ouchi, Masami [Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa City, Chiba 77-8582 (Japan)

    2011-12-10

    We present Keck spectroscopic observations of z > 6 Lyman-break galaxy (LBG) candidates in the Subaru Deep Field (SDF). The candidates were selected as i'-dropout objects down to z' = 27 AB magnitudes from an ultra-deep SDF z'-band image. With the Keck spectroscopy we identified 19 LBGs with prominent Ly{alpha} emission lines at 6 {<=} z {<=} 6.4. The median value of the Ly{alpha} rest-frame equivalent widths (EWs) is {approx}50 A, with four EWs >100 A. This well-defined spectroscopic sample spans a UV-continuum luminosity range of -21.8 {<=} M{sub UV} {<=} -19.5 (0.6 {approx} 5 L*{sub UV}) and a Ly{alpha} luminosity range of (0.3-3) Multiplication-Sign 10{sup 43} erg s{sup -1} (0.3-3 L*{sub Ly{alpha}}). We derive the UV and Ly{alpha} luminosity functions (LFs) from our sample at (z) {approx} 6.2 after we correct for sample incompleteness. We find that our measurement of the UV LF is consistent with the results of previous studies based on photometric LBG samples at 5 < z < 7. Our Ly{alpha} LF is also generally in agreement with the results of Ly{alpha}-emitter surveys at z {approx} 5.7 and 6.6. This study shows that deep spectroscopic observations of LBGs can provide unique constraints on both the UV and Ly{alpha} LFs at z > 6.

  19. Interaction mechanisms between organic UV filters and bovine serum albumin as determined by comprehensive spectroscopy exploration and molecular docking.

    Science.gov (United States)

    Ao, Junjie; Gao, Li; Yuan, Tao; Jiang, Gaofeng

    2015-01-01

    Organic UV filters are a group of emerging PPCP (pharmaceuticals and personal care products) contaminants. Current information is insufficient to understand the in vivo processes and health risks of organic UV filters in humans. The interaction mechanism of UV filters with serum albumin provides critical information for the health risk assessment of these active ingredients in sunscreen products. This study investigates the interaction mechanisms of five commonly used UV filters (2-hydroxy-4-methoxybenzophenone, BP-3; 2-ethylhexyl 4-methoxycinnamate, EHMC; 4-methylbenzylidene camphor, 4-MBC; methoxydibenzoylmethane, BDM; homosalate, HMS) with bovine serum albumin (BSA) by spectroscopic measurements of fluorescence, circular dichroism (CD), competitive binding experiments and molecular docking. Our results indicated that the fluorescence of BSA was quenched by these UV filters through a static quenching mechanism. The values of the binding constant (Ka) ranged from (0.78±0.02)×10(3) to (1.29±0.01)×10(5) L mol(-1). Further exploration by synchronous fluorescence and CD showed that the conformation of BSA was demonstrably changed in the presence of these organic UV filters. It was confirmed that the UV filters can disrupt the α-helical stability of BSA. Moreover, the results of molecular docking revealed that the UV filter molecule is located in site II (sub-domain IIIA) of BSA, which was further confirmed by the results of competitive binding experiments. In addition, binding occurred mainly through hydrogen bonding and hydrophobic interaction. This study raises critical concerns regarding the transportation, distribution and toxicity effects of organic UV filters in human body. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Effect of UV irradiation on Echinaceae purpureae interactions with free radicals examined by an X-band (9.3 GHz) EPR spectroscopy.

    Science.gov (United States)

    Ramos, Paweł; Pilawa, Barbara

    The effect of UVA (315-400 nm) irradiation on Echinaceae purpureae interactions with free radicals was examined by the use of electron paramagnetic resonance (EPR) spectroscopy. The changes of antioxidant properties of E. purpureae with time of UV irradiation from 10 to 110 min (10 min steps) were determined. DPPH as the paramagnetic reference was used in this study. Changes of EPR signals of the reference after interactions with nonirradiated and UV-irradiated E. purpureae were detected. Interactions of the tested E. purpureae samples caused decrease of the EPR signal of DPPH as the result of its antioxidant properties. The decrease of the amplitude of EPR line of DPPH was lower for interactions with UV-irradiated E. purpureae . EPR examination confirmed antioxidant properties of E. purpureae . The weaker antioxidant properties of E. purpureae after UV irradiation were pointed out. E. purpureae should be storage in the dark. The tests bring to light usefulness of electron paramagnetic resonance with microwave frequency of 9.3 GHz (an X-band) in examination of storage conditions of pharmacological herbs.

  1. Electron spectroscopy

    International Nuclear Information System (INIS)

    Hegde, M.S.

    1979-01-01

    An introduction to the various techniques in electron spectroscopy is presented. These techniques include: (1) UV Photoelectron spectroscopy, (2) X-ray Photoelectron spectroscopy, (3) Auger electron spectroscopy, (4) Electron energy loss spectroscopy, (5) Penning ionization spectroscopy and (6) Ion neutralization spectroscopy. The radiations used in each technique, the basis of the technique and the special information obtained in structure determination in atoms and molecules by each technique are summarised. (A.K.)

  2. UV-vis spectroscopy and colorimetric models for detecting anthocyanin-metal complexes in plants: An overview of in vitro and in vivo techniques.

    Science.gov (United States)

    Fedenko, Volodymyr S; Shemet, Sergiy A; Landi, Marco

    2017-05-01

    Although anthocyanin (ACN) biosynthesis is one of the best studied pathways of secondary metabolism in plants, the possible physiological and ecological role(s) of these pigments continue to intrigue scientists. Like other dihydroxy B-ring substituted flavonoids, ACNs have an ability to bind metal and metalloid ions, a property that has been exploited for a variety of purposes. For example, the metal binding ability may be used to stabilize ACNs from plant food sources, or to modify their colors for using them as food colorants. The complexation of metals with cyanidin derivatives can also be used as a simple, sensitive, cheap, and rapid method for determination concentrations of several metals in biological and environmental samples using UV-vis spectroscopy. Far less information is available on the ecological significance of ACN-metal complexes in plant-environment interactions. Metalloanthocyanins (protocyanin, nemophilin, commelinin, protodelphin, cyanosalvianin) are involved in the copigmentation phenomenon that leads to blue-pigmented petals, which may facilitate specific plant-pollinator interactions. ACN-metal formation and compartmentation into the vacuole has also been proposed to be part of an orchestrated detoxification mechanism in plants which experience metal/metalloid excess. However, investigations into ACN-metal interactions in plant biology may be limited because of the complexity of the analytical techniques required. To address this concern, here we describe simple methods for the detection of ACN-metal both in vitro and in vivo using UV-vis spectroscopy and colorimetric models. In particular, the use of UV-vis spectra, difference absorption spectra, and colorimetry techniques will be described for in vitro determination of ACN-metal features, whereas reflectance spectroscopy and colorimetric parameters related to CIE L * a * b * and CIE XYZ systems will be detailed for in vivo analyses. In this way, we hope to make this high-informative tool

  3. Nanoflow electrospinning serial femtosecond crystallography

    Science.gov (United States)

    Sierra, Raymond G.; Laksmono, Hartawan; Kern, Jan; Tran, Rosalie; Hattne, Johan; Alonso-Mori, Roberto; Lassalle-Kaiser, Benedikt; Glöckner, Carina; Hellmich, Julia; Schafer, Donald W.; Echols, Nathaniel; Gildea, Richard J.; Grosse-Kunstleve, Ralf W.; Sellberg, Jonas; McQueen, Trevor A.; Fry, Alan R.; Messerschmidt, Marc M.; Miahnahri, Alan; Seibert, M. Marvin; Hampton, Christina Y.; Starodub, Dmitri; Loh, N. Duane; Sokaras, Dimosthenis; Weng, Tsu-Chien; Zwart, Petrus H.; Glatzel, Pieter; Milathianaki, Despina; White, William E.; Adams, Paul D.; Williams, Garth J.; Boutet, Sébastien; Zouni, Athina; Messinger, Johannes; Sauter, Nicholas K.; Bergmann, Uwe; Yano, Junko; Yachandra, Vittal K.; Bogan, Michael J.

    2012-01-01

    An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14–3.1 µl min−1 to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed at 0.17 µl min−1 and diffracted to beyond 4 Å resolution, producing 14 000 indexable diffraction patterns, or four per second, from 140 µg of protein. Nanoflow electrospinning extends SFX to biological samples that necessitate minimal sample consumption. PMID:23090408

  4. Study of the electronic structure of pure aluminium, aluminium oxide and nitride by spectroscopy of electrons excited under electronic and photonic bombardment (X and UV)

    International Nuclear Information System (INIS)

    Gautier-Soyer, Martine

    1985-01-01

    This research thesis reports the use of electron spectroscopy with electrons excited under electronic or photonic (X or UV) bombardment for the study of electronic state density of aluminium, aluminium oxide (Al 2 O 3 ) and aluminium nitride (AlN). The objective is to get an insight into phenomena related to technological problems of adherence, wear, lubrication, corrosion or breakdown met in metals, insulators and semiconductors. The author highlighted the presence of occupied surface states on Al(111) and Al(100), and electronic levels localised in the forbidden band of Al 2 O 3 and AlN, induced by structural defects which promote surface reactivity [fr

  5. Development of a Fourier transform infrared spectroscopy coupled to UV-Visible analysis technique for aminosides and glycopeptides quantitation in antibiotic locks.

    Science.gov (United States)

    Sayet, G; Sinegre, M; Ben Reguiga, M

    2014-01-01

    Antibiotic Lock technique maintains catheters' sterility in high-risk patients with long-term parenteral nutrition. In our institution, vancomycin, teicoplanin, amikacin and gentamicin locks are prepared in the pharmaceutical department. In order to insure patient safety and to comply to regulatory requirements, antibiotic locks are submitted to qualitative and quantitative assays prior to their release. The aim of this study was to develop an alternative quantitation technique for each of these 4 antibiotics, using a Fourier transform infrared (FTIR) coupled to UV-Visible spectroscopy and to compare results to HPLC or Immunochemistry assays. Prevalidation studies permitted to assess spectroscopic conditions used for antibiotic locks quantitation: FTIR/UV combinations were used for amikacin (1091-1115cm(-1) and 208-224nm), vancomycin (1222-1240cm(-1) and 276-280nm), and teicoplanin (1226-1230cm(-1) and 278-282nm). Gentamicin was quantified with FTIR only (1045-1169cm(-1) and 2715-2850cm(-1)) due to interferences in UV domain of parabens, preservatives present in the commercial brand used to prepare locks. For all AL, the method was linear (R(2)=0.996 to 0.999), accurate, repeatable (intraday RSD%: from 2.9 to 7.1% and inter-days RSD%: 2.9 to 5.1%) and precise. Compared to the reference methods, the FTIR/UV method appeared tightly correlated (Pearson factor: 97.4 to 99.9%) and did not show significant difference in recovery determinations. We developed a new simple reliable analysis technique for antibiotics quantitation in locks using an original association of FTIR and UV analysis, allowing a short time analysis to identify and quantify the studied antibiotics. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  6. Reaction pathways of proton transfer in hydrogen-bonded phenol-carboxylate complexes explored by combined UV-vis and NMR spectroscopy.

    Science.gov (United States)

    Koeppe, Benjamin; Tolstoy, Peter M; Limbach, Hans-Heinrich

    2011-05-25

    Combined low-temperature NMR/UV-vis spectroscopy (UVNMR), where optical and NMR spectra are measured in the NMR spectrometer under the same conditions, has been set up and applied to the study of H-bonded anions A··H··X(-) (AH = 1-(13)C-2-chloro-4-nitrophenol, X(-) = 15 carboxylic acid anions, 5 phenolates, Cl(-), Br(-), I(-), and BF(4)(-)). In this series, H is shifted from A to X, modeling the proton-transfer pathway. The (1)H and (13)C chemical shifts and the H/D isotope effects on the latter provide information about averaged H-bond geometries. At the same time, red shifts of the π-π* UV-vis absorption bands are observed which correlate with the averaged H-bond geometries. However, on the UV-vis time scale, different tautomeric states and solvent configurations are in slow exchange. The combined data sets indicate that the proton transfer starts with a H-bond compression and a displacement of the proton toward the H-bond center, involving single-well configurations A-H···X(-). In the strong H-bond regime, coexisting tautomers A··H···X(-) and A(-)···H··X are observed by UV. Their geometries and statistical weights change continuously when the basicity of X(-) is increased. Finally, again a series of single-well structures of the type A(-)···H-X is observed. Interestingly, the UV-vis absorption bands are broadened inhomogeneously because of a distribution of H-bond geometries arising from different solvent configurations.

  7. The success story of crystallography.

    Science.gov (United States)

    Schwarzenbach, Dieter

    2012-01-01

    Diffractionists usually place the birth of crystallography in 1912 with the first X-ray diffraction experiment of Friedrich, Knipping and Laue. This discovery propelled the mathematical branch of mineralogy to global importance and enabled crystal structure determination. Knowledge of the geometrical structure of matter at atomic resolution had revolutionary consequences for all branches of the natural sciences: physics, chemistry, biology, earth sciences and material science. It is scarcely possible for a single person in a single article to trace and appropriately value all of these developments. This article presents the limited, subjective view of its author and a limited selection of references. The bulk of the article covers the history of X-ray structure determination from the NaCl structure to aperiodic structures and macromolecular structures. The theoretical foundations were available by 1920. The subsequent success of crystallography was then due to the development of diffraction equipment, the theory of the solution of the phase problem, symmetry theory and computers. The many structures becoming known called for the development of crystal chemistry and of data banks. Diffuse scattering from disordered structures without and with partial long-range order allows determination of short-range order. Neutron and electron scattering and diffraction are also mentioned.

  8. Neutron Crystallography for the Study of Hydrogen Bonds in Macromolecules

    Directory of Open Access Journals (Sweden)

    Esko Oksanen

    2017-04-01

    Full Text Available Abstract: The hydrogen bond (H bond is one of the most important interactions that form the foundation of secondary and tertiary protein structure. Beyond holding protein structures together, H bonds are also intimately involved in solvent coordination, ligand binding, and enzyme catalysis. The H bond by definition involves the light atom, H, and it is very difficult to study directly, especially with X-ray crystallographic techniques, due to the poor scattering power of H atoms. Neutron protein crystallography provides a powerful, complementary tool that can give unambiguous information to structural biologists on solvent organization and coordination, the electrostatics of ligand binding, the protonation states of amino acid side chains and catalytic water species. The method is complementary to X-ray crystallography and the dynamic data obtainable with NMR spectroscopy. Also, as it gives explicit H atom positions, it can be very valuable to computational chemistry where exact knowledge of protonation and solvent orientation can make a large difference in modeling. This article gives general information about neutron crystallography and shows specific examples of how the method has contributed to structural biology, structure-based drug design; and the understanding of fundamental questions of reaction mechanisms.

  9. The founding and development of X-ray crystallography

    International Nuclear Information System (INIS)

    Mai Zhenhong

    2014-01-01

    2014 is the centennial of X-ray crystallography. Crystals have played an important role in our lives and in the development of society throughout these 100 years. In July 2012 the 66th General Assembly of the United Nations declared 2014 to be the official International Year of Crystallography (IYCr2014). The discovery of X-ray diffraction by crystals has had a profound impact on science and technology worldwide. It provides for us a distinct image of the arrangement of atoms or/and molecules in crystals. The development of X-ray spectroscopy has made it possible for us to understand the laws of atomic structure, and thus to identify the elements in all kinds of matter. In this article the greatest events in the history of X-ray crystallography, including the development of X-ray sources, detectors, experimental data analysis, and experimental methods are reviewed to commemorate the pioneers who made such important contributions to science and technology. (author)

  10. Recent advances in racemic protein crystallography.

    Science.gov (United States)

    Yan, Bingjia; Ye, Linzhi; Xu, Weiliang; Liu, Lei

    2017-09-15

    Solution of the three-dimensional structures of proteins is a critical step in deciphering the molecular mechanisms of their bioactivities. Among the many approaches for obtaining protein crystals, racemic protein crystallography has been developed as a unique method to solve the structures of an increasing number of proteins. Exploiting unnatural protein enantiomers in crystallization and resolution, racemic protein crystallography manifests two major advantages that are 1) to increase the success rate of protein crystallization, and 2) to obviate the phase problem in X-ray diffraction. The requirement of unnatural protein enantiomers in racemic protein crystallography necessitates chemical protein synthesis, which is hitherto accomplished through solid phase peptide synthesis and chemical ligation reactions. This review highlights the fundamental ideas of racemic protein crystallography and surveys the harvests in the field of racemic protein crystallography over the last five years from early 2012 to late 2016. Copyright © 2017. Published by Elsevier Ltd.

  11. UV-Vis spectroscopy with chemometric data treatment. An option for on-line control in nuclear industry

    International Nuclear Information System (INIS)

    Kirsanov, Dmitry; Legin, Andrey

    2017-01-01

    Chemometrics can be very useful for the classical field of UV-Vis determination of metals in aqueous solutions. A conventional approach consisting of using selective bands in a univariate mode is often not applicable to the real-world samples from e.g. hydrometallurgical processes, because of overlapping signals, light scattering on foreign particles, gas bubble formation, etc. And this is where chemometrics can do a good job. This paper overviews certain contributions to the field of multivariate data processing of UV-Vis spectra for seemingly simple case of metal detection in aqueous solutions. Special attention is given to applications in nuclear technology field. (author)

  12. Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1968-01-01

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

  13. IN-VIVO DIAGNOSIS OF CHEMICALLY INDUCED MELANOMA IN AN ANIMAL MODEL USING UV-VISIBLE AND NIR ELASTIC SCATTERING SPECTROSCOPY: PRELIMINARY TESTING.

    Energy Technology Data Exchange (ETDEWEB)

    C. A' AMAR; R. LEY; ET AL

    2001-01-01

    Elastic light scattering spectroscopy (ESS) has the potential to provide spectra that contain both morphological and chromophore information from tissue. We report on a preliminary study of this technique, with the hope of developing a method for diagnosis of highly-pigmented skin lesions, commonly associated with skin cancer. Four opossums were treated with dimethylbenz(a)anthracene to induce both malignant melanoma and benign pigmented lesions. Skin lesions were examined in vivo using both UV-visible and near infrared (NIR) ESS, with wavelength ranges of 330-900 nm and 900-1700 nm, respectively. Both portable systems used identical fiber-optic probe geometry throughout all of the measurements. The core diameters for illuminating and collecting fibers were 400 and 200 {micro}m, respectively, with center-to-center separation of 350 {micro}m. The probe was placed in optical contact with the tissue under investigation. Biopsies from lesions were analyzed by two standard histopathological procedures. Taking into account only the biopsied lesions, UV-visible ESS showed distinct spectral correlation for 11/13 lesions. The NIR-ESS correlated well with 12/13 lesions correctly. The results of these experiments showed that UV-visible and NIR-ESS have the potential to classify benign and malignant skin lesions, with encouraging agreement to that provided by standard histopathological examination. These initial results show potential for ESS based diagnosis of pigmented skin lesions, but further trials are required in order to substantiate the technique.

  14. Adsorption characteristics of Au nanoparticles onto poly(4-vinylpyridine) surface revealed by QCM, AFM, UV/vis, and Raman scattering spectroscopy.

    Science.gov (United States)

    Kim, Kwan; Ryoo, Hyunwoo; Lee, Yoon Mi; Shin, Kuan Soo

    2010-02-15

    In this work, we report that the adsorption and aggregation processes of Au nanoparticles on a polymer surface can be monitored by means of surface-enhanced Raman scattering (SERS) spectroscopy. Specifically, we were able to analyze the adsorption process of citrate-stabilized Au nanoparticles onto a film of poly(4-vinylpyridine) (P4VP) by taking a series of SERS spectra, during the self-assembly of Au nanoparticles onto the polymer film. In order to better analyze the SERS spectra, we separately conducted quartz crystal microbalance (QCM), UV/vis spectroscopy, and atomic force microscope (AFM) measurements. The adsorption kinetics revealed by QCM under the in situ conditions was in fair agreement with that determined by the ex situ AFM measurement. The number of Au nanoparticles adsorbed on P4VP increased almost linearly with time: 265 Au nanoparticles per 1microm(2) were adsorbed on the P4VP film after 6h of immersion. The SERS signal measured in the ex situ condition showed a more rapid increase than that of QCM; however, its increasing pattern was quite similar to that of UV/vis absorbance at longer wavelengths, suggesting that Au nanoparticles actually became agglomerated on P4VP. Copyright 2009 Elsevier Inc. All rights reserved.

  15. Spectroscopy

    CERN Document Server

    Walker, S

    1976-01-01

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

  16. Advances in powder diffraction crystallography

    International Nuclear Information System (INIS)

    Magneli, A.

    1986-01-01

    This is the first conference to be arranged within the framework of an agreement on scientific exchange and co-operation between l Academie des Sciences de l Institut de France and the Royal Swedish Academy of Sciences. The responsibility for the scientific program of the conference has been shared between members of the two Academies. The contributions include glimpses of the historical background and broad reviews of the present status of development and of recent work in powder crystallography. Reports are given on a number of studies, basic as well as applied in character, currently conducted in the two countries in a large variety of fields. Prospects of further developments in the area are also presented

  17. Macromolecular crystallography research at Trombay

    International Nuclear Information System (INIS)

    Kannan, K.K.; Chidamrabam, R.

    1983-01-01

    Neutron diffraction studies of hydrogen positions in small molecules of biological interest at Trombay have provided valuable information that has been used in protein and enzyme structure model-building and in developing hydrogen bond potential functions. The new R-5 reactor is expected to provide higher neutron fluxes and also make possible small-angle neutron scattering studies of large biomolecules and bio-aggregates. In the last few years infrastructure facilities have also been established for macromolecular x-ray crystallography research. Meanwhile, the refinement of carbonic hydrases and lyysozyme structures have been carried out and interesting results obtained on protein dynamics and structure-function relationships. Some interesting presynaptic toxin phospholipases have also taken up for study. (author)

  18. Characterization of pigment/binder - systems in arts via FTIR and UV/Vis/NIR - spectroscopy with special consideration of nondestructive methods

    International Nuclear Information System (INIS)

    Vetter, W.A.

    2014-01-01

    The main focus of this doctoral thesis is on the non-destructive analysis of art objects by using compound specific reflection-UV/Vis/NIR and reflection-FTIR spectroscopy. Based on commercially available instruments, measuring systems have been designed and built to meet the specific requirements of material analysis in the field of art. These systems have been utilized to analyse different types of art objects (watercolour paintings, easel paintings, contemporary graphic art objects) in order to identify the materials used by the artists. Furthermore, two new procedures are presented which allow to build up adequate reference databases from only minimal sample amounts of original watercolour materials of the 19th century. This is a crucial point as both methods require references for the identification of the materials. The results obtained demonstrate that UV/Vis/NIR and FTIR spectroscopy in reflection mode enable the non-destructive identification of a variety of both, organic and inorganic materials, particularly in combination with element specific XRF (X-ray fluorescence analysis) and thus are valuable tools for the analysis of cultural heritage objects. Furthermore, the results have shown that a comparison of the complementary methods strongly facilitated the evaluation of spectra obtained by the particular analytical techniques and hence reliable results could be obtained in many cases. As expected, several frequently used pigments e.g. carbon based blacks, earth pigments and lake pigments could not be identified unambiguously due to methodical limitations. Therefore, the use of additional complementary methods such as Raman spectroscopy and X-ray diffraction (XRD) would be highly desirable. Except a few examples, the characteristics of the radiation used for the investigations did not allow to draw conclusions about the distribution of materials in multilayer structures. For this reason, it still remains necessary to analyse cross-sections of samples for a

  19. Laboratory spectroscopy of meteorite samples at UV-vis-NIR wavelengths: Analysis and discrimination by principal components analysis

    Science.gov (United States)

    Penttilä, Antti; Martikainen, Julia; Gritsevich, Maria; Muinonen, Karri

    2018-02-01

    Meteorite samples are measured with the University of Helsinki integrating-sphere UV-vis-NIR spectrometer. The resulting spectra of 30 meteorites are compared with selected spectra from the NASA Planetary Data System meteorite spectra database. The spectral measurements are transformed with the principal component analysis, and it is shown that different meteorite types can be distinguished from the transformed data. The motivation is to improve the link between asteroid spectral observations and meteorite spectral measurements.

  20. Determination of Phosphate in Water Samples of Nashik District (Maharashtra State, India Rivers by UV-Visible Spectroscopy

    Directory of Open Access Journals (Sweden)

    Sanjeevan J. Kharat

    2009-01-01

    Full Text Available The major rivers of Nashik District (Maharashtra State, India are Godavari, Kadawa, Girna, Punad and Mosam. The major water pollutant of Nashik District Rivers is Phosphate. The amount of phosphate has been determined by the molybdenum blue phosphorous method in conjugation with UV-Visible Spectrophotometer. The data has been analyzed by least square method. The more phosphate polluted river in Nashik district is Godavari. The least phosphate polluted river in Nashik District is Punad.

  1. Determination of Phosphate in Water Samples of Nashik District (Maharashtra State, India) Rivers by UV-Visible Spectroscopy

    OpenAIRE

    Kharat, Sanjeevan J.; Pagar, Sanjay D.

    2009-01-01

    The major rivers of Nashik District (Maharashtra State, India) are Godavari, Kadawa, Girna, Punad and Mosam. The major water pollutant of Nashik District Rivers is Phosphate. The amount of phosphate has been determined by the molybdenum blue phosphorous method in conjugation with UV-Visible Spectrophotometer. The data has been analyzed by least square method. The more phosphate polluted river in Nashik district is Godavari. The least phosphate polluted river in Nashik District is Punad.

  2. Revealing Lattice Expansion of Small-Pore Zeolite Catalysts during the Methanol-to-Olefins Process Using Combined Operando X-ray Diffraction and UV-vis Spectroscopy.

    Science.gov (United States)

    Goetze, Joris; Yarulina, Irina; Gascon, Jorge; Kapteijn, Freek; Weckhuysen, Bert M

    2018-03-02

    In small-pore zeolite catalysts, where the size of the pores is limited by eight-ring windows, aromatic hydrocarbon pool molecules that are formed inside the zeolite during the Methanol-to-Olefins (MTO) process cannot exit the pores and are retained inside the catalyst. Hydrocarbon species whose size is comparable to the size of the zeolite cage can cause the zeolite lattice to expand during the MTO process. In this work, the formation of retained hydrocarbon pool species during MTO at a reaction temperature of 400 °C was followed using operando UV-vis spectroscopy. During the same experiment, using operando X-ray Diffraction (XRD), the expansion of the zeolite framework was assessed, and the activity of the catalyst was measured using online gas chromatography (GC). Three different small-pore zeolite frameworks, i.e., CHA, DDR, and LEV, were compared. It was shown using operando XRD that the formation of retained aromatic species causes the zeolite lattice of all three frameworks to expand. Because of the differences in the zeolite framework dimensions, the nature of the retained hydrocarbons as measured by operando UV-vis spectroscopy is different for each of the three zeolite frameworks. Consequently, the magnitude and direction of the zeolite lattice expansion as measured by operando XRD also depends on the specific combination of the hydrocarbon species and the zeolite framework. The catalyst with the CHA framework, i.e., H-SSZ-13, showed the biggest expansion: 0.9% in the direction along the c -axis of the zeolite lattice. For all three zeolite frameworks, based on the combination of operando XRD and operando UV-vis spectroscopy, the hydrocarbon species that are likely to cause the expansion of the zeolite cages are presented; methylated naphthalene and pyrene in CHA, 1-methylnaphthalene and phenalene in DDR, and methylated benzene and naphthalene in LEV. Filling of the zeolite cages and, as a consequence, the zeolite lattice expansion causes the

  3. Researches towards establishing procedures and protocols for testing instrumental accuracy and reproducibility of UV-visible microvolume drop spectroscopy instrumentation

    International Nuclear Information System (INIS)

    McMillan, N D; O'Neill, M; Riedel, S; Arthure, K; Hammond, J; Smith, S R P

    2011-01-01

    The Reference Materials (DTRM-2SG and DTRM-4SG) for validation of the absorbance scale for a Transmitted Light Drop Analyser (TLDA) have been developed specifically for microvolume spectroscopy. The approach to the calibration of photometric accuracy and reproducibility is briefly illustrated. These materials can be used also for wavelength checks. The study addresses however a wider range of issues for microvolume spectroscopy quality assurance. This study concludes with a general discussion of this quality programme on the important practical and philosophical issues needed for drop science quality systems.

  4. Application of UV-visible absorption spectroscopy combined with two-dimensional correlation for insight into DOM fractions from native halophyte soils in a larger estuarine delta.

    Science.gov (United States)

    Wei, Huaibin; Yu, Huibin; Pan, Hongwei; Gao, Hongjie

    2018-05-01

    UV-visible absorption spectroscopy combined with principal component analysis (PCA) and two-dimensional correlation (2D correlation) is used to trace components of dissolved organic matter (DOM) extracted from soils in a larger estuarine delta and to investigate spatial variations of DOM fractions. Soil samples of different depths were collected from native halophyte soils along a saline gradient, i.e., Suaeda salsa Comm. (SSC), Chenopodium album Comm. (CAC), Phragmites australis Comm. (PAC), and Artemisia selengensis Comm. (ASC). Molecular weights of DOM within the SSC soil profile were the lowest, followed by the CAC, PAC, and ASC soil profiles. Humification degree of DOM within the ASC soil profile was the highest, followed by the PAC, SSC, and CAC soil profiles. DOM within the soil profiles mainly contained phenolic, carboxylic, microbial products, and aromatic and alkyl groups through the PCA, which presented the significant differentiation among the four native halophyte soil profiles. The 2D UV correlation spectra of DOM within the SSC soil profile indicated that the variations of the phenolic groups were the largest, followed by the carboxylic groups, microbial products, and humified organic materials according to the band changing order of 285 → 365 → 425 → 520 nm. The 2D UV correlation spectra of DOM within the CAC soil profiles determined that the decreasing order of the variations was phenolic groups > carboxylic groups > microbial products according the band changing order of 285 → 365 → 425 nm. The 2D UV correlation spectra of DOM within the PAC soil profile proved that the variations of the phenolic groups were larger than those of the carboxylic groups according to the band changing order of 285 → 365 nm. The 2D UV correlation spectra of DOM within the ASC soil profile demonstrated that the variations of the phenolic groups were larger than those of the other DOM fractions according to the broad cross-peak at

  5. NATO Advanced Study Institute on Electron Crystallography

    CERN Document Server

    Weirich, Thomas E; Zou, Xiaodong

    2006-01-01

    During the last decade we have been witness to several exciting achievements in electron crystallography. This includes structural and charge density studies on organic molecules complicated inorganic and metallic materials in the amorphous, nano-, meso- and quasi-crystalline state and also development of new software, tailor-made for the special needs of electron crystallography. Moreover, these developments have been accompanied by a now available new generation of computer controlled electron microscopes equipped with high-coherent field-emission sources, cryo-specimen holders, ultra-fast CCD cameras, imaging plates, energy filters and even correctors for electron optical distortions. Thus, a fast and semi-automatic data acquisition from small sample areas, similar to what we today know from imaging plates diffraction systems in X-ray crystallography, can be envisioned for the very near future. This progress clearly shows that the contribution of electron crystallography is quite unique, as it enables to r...

  6. Status and prospects of macromolecular crystallography

    Indian Academy of Sciences (India)

    technique that could be completely automated in most cases. ... major challenge in macromolecular crystallography today is ... tial characterization of crystals in the home source and make a ... opportunities for a generation of structural biolo-.

  7. History of protein crystallography in China.

    Science.gov (United States)

    Rao, Zihe

    2007-06-29

    China has a strong background in X-ray crystallography dating back to the 1920s. Protein crystallography research in China was first developed following the successful synthesis of insulin in China in 1966. The subsequent determination of the three-dimensional structure of porcine insulin made China one of the few countries which could determine macromolecular structures by X-ray diffraction methods in the late 1960s and early 1970s. After a slow period during the 1970s and 1980s, protein crystallography in China has reached a new climax with a number of outstanding accomplishments. Here, I review the history and progress of protein crystallography in China and detail some of the recent research highlights, including the crystal structures of two membrane proteins as well as the structural genomics initiative in China.

  8. Characterization of the alpha and beta subunits of casein kinase 2 by far-UV CD spectroscopy

    DEFF Research Database (Denmark)

    Issinger, O G; Brockel, C; Boldyreff, B

    1992-01-01

    Although Chou-Fasman calculations of the secondary structure of recombinant casein kinase 2 subunits alpha and beta suggest they have a similar overall conformation, circular dichroism (CD) studies show that substantial differences in the conformation of the two subunits exist. In addition......, no changes in the far-UV CD spectrum of the alpha subunit are observed in the presence of casein or the synthetic decapeptide substrate RRRDDDSDDD. Furthermore, the alpha-helical structure of the alpha subunit (but not the beta subunit) can be increased in the presence of stoichiometric amounts of heparin...

  9. Feasibility of UV-VIS-Fluorescence spectroscopy combined with pattern recognition techniques to authenticate a new category of plant food supplements.

    Science.gov (United States)

    Boggia, Raffaella; Turrini, Federica; Anselmo, Marco; Zunin, Paola; Donno, Dario; Beccaro, Gabriele L

    2017-07-01

    Bud extracts, named also "gemmoderivatives", are a new category of natural products, obtained macerating meristematic fresh tissues of trees and plants. In the European Community these botanical remedies are classified as plant food supplements. Nowadays these products are still poorly studied, even if they are widely used and commercialized. Several analytical tools for the quality control of these very expensive supplements are urgently needed in order to avoid mislabelling and frauds. In fact, besides the usual quality controls common to the other botanical dietary supplements, these extracts should be checked in order to quickly detect if the cheaper adult parts of the plants are deceptively used in place of the corresponding buds whose harvest-period and production are extremely limited. This study aims to provide a screening analytical method based on UV-VIS-Fluorescence spectroscopy coupled to multivariate analysis for a rapid, inexpensive and non-destructive quality control of these products.

  10. Stratospheric OClO and NO2 measured by groundbased UV/Vis-spectroscopy in Greenland in January and February 1990 and 1991

    Science.gov (United States)

    Roth, A.; Perner, D.

    1994-01-01

    Groundbased UV/Vis-spectroscopy of zenith scattered sunlight was performed at Sondre Stromfjord (Greenland) during Jan/Feb 1990 and Jan/Feb 1991. Considerable amounts of OClO were observed during both campaigns. Maximum OClO vertical column densities at 92 deg solar zenith angle (SZA) were 7.4 x 10(exp 13) molec/sq cm in 1990 and 5.7 x 10(exp 13) molec/sq cm in 1991 (chemical enhancement is included in the calculation of the air mass factor (AMF)). A threshold seems to exist for OClO detection: OClO was detected on every day when the potential vorticity at the 475 K level of potential temperature was higher than 35 x 10(exp -6)Km(exp 2)kg(exp -1)s(exp -1). NO2 vertical columns lower than 1 x 10(exp 15) molec/sq cm were frequently observed in both winters.

  11. Depth probing of the hydride formation process in thin Pd films by combined electrochemistry and fiber optics-based in situ UV/vis spectroscopy.

    Science.gov (United States)

    Wickman, Björn; Fredriksson, Mattias; Feng, Ligang; Lindahl, Niklas; Hagberg, Johan; Langhammer, Christoph

    2015-07-15

    We demonstrate a flexible combined electrochemistry and fiber optics-based in situ UV/vis spectroscopy setup to gain insight into the depth evolution of electrochemical hydride and oxide formation in Pd films with thicknesses of 20 and 100 nm. The thicknesses of our model systems are chosen such that the films are thinner or significantly thicker than the optical skin depth of Pd to create two distinctly different situations. Low power white light is irradiated on the sample and analyzed in three different configurations; transmittance through, and, reflectance from the front and the back side of the film. The obtained optical sensitivities correspond to fractions of a monolayer of adsorbed or absorbed hydrogen (H) and oxygen (O) on Pd. Moreover, a combined simultaneous readout obtained from the different optical measurement configurations provides mechanistic insights into the depth-evolution of the studied hydrogenation and oxidation processes.

  12. Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

    Science.gov (United States)

    Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

    2016-05-15

    Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Fluorine substitution and nonconventional OH...pi intramolecular bond: high-resolution UV spectroscopy and ab initio calculations of 2-(p-fluorophenyl)ethanol.

    Science.gov (United States)

    Karaminkov, Rosen; Chervenkov, Sotir; Neusser, Hans J

    2008-05-21

    The para-fluorinated flexible neurotransmitter analogue 2-phenylethanol has been investigated by highly resolved resonance-enhanced two-photon ionisation two-colour UV laser spectroscopy with mass resolution and ab initio structural optimisations and energy calculations. Two stable conformations, gauche and anti, separated by a high potential barrier have been identified in the cold molecular beam by rotational analysis of the vibronic band structures. The theoretically predicted higher-lying conformations most likely relax to these two structures during the adiabatic expansion. The lowest-energy gauche conformer is stabilised by an intramolecular nonconventional OH...pi-type hydrogen bond between the terminal OH group of the side chain and the pi electrons of the phenyl ring. The good agreement between the experimental and theoretical results demonstrates that even the substitution with a strongly electronegative atom of 2-phenylethanol at the para position has no noticeable effect on the strength and orientation of the OH...pi bond.

  14. Crystallography beyond periodic Crystal perfection

    International Nuclear Information System (INIS)

    Estevez-Rams, E.

    2008-01-01

    Full text: The discovery of the quasi-crystals [D. Schechtman et. Al., Phys.] Rev. Lett. [53, 1951-1953 (1984)] made very narrow definition of the crystalline state based on the periodicity of a local arrangement of atoms. Since the definition of this State has been a matter of much controversy [G.R. Desiraju, Nature 423, 485 (2003); S. van Smaalen, IUCR Aperiodic Commission Reports. August 7, 2002; International Union of Crystallography. Report of the Executive Committee for 1991; ACTA Cryst. A48, 922-946 (1992)]. We will make a presentation of the current time of the crystallography in this regard from the conceptual point of view. We show the use of the formalism of algorithmic complexity or Kolmogorov [M. Li and P. Vitanyi, An Introduction to Kolmogorov Complexity and Its Applications (Springer Verlag, Heidelberg, 1993), W.H. Zurek, Phys.] Rev. 40, 4731 (1989); Nature 341, 119-124 (1989)] provides a different perspective on the nature of the Crystallographic order. Infinite crystals can be considered solid with zero algorithmic complexities by atom. Show statistical analysis of inorganic compounds [J.L.C. Daams et al., Atlas of Crystal Structure Types for Intermetallic Phases (ASM International, Ohio, 1991), Fachinformationszentrum/NIST Inorganic Crystal Structure Database, Karlsruhe (2003) icsd.fkf.mpg.de] demonstrating that the minimization of complexity is a trend in the crystalline arrangement. We will then compare the degree of disorder of some typical solids according to their algorithmic complexity. Finally, space diffraction will be studied from this same perspective and will be discussed that zero algorithmic complexities by point in space of diffraction does not necessarily imply the same thing for the Atomic arrangement. The discrete portion of the diffraction pattern is a fingerprint of the underlying order but not the actual existence of long-range order. Experimental results will be showcased [E. Estévez-Rams et al., Physical Review B, 63 (2001

  15. Structure determination by X-ray crystallography

    CERN Document Server

    Ladd, M F C

    1977-01-01

    Crystallography may be described as the science of the structure of materi­ als, using this word in its widest sense, and its ramifications are apparent over a broad front of current scientific endeavor. It is not surprising, therefore, to find that most universities offer some aspects of crystallography in their undergraduate courses in the physical sciences. It is the principal aim of this book to present an introduction to structure determination by X-ray crystal­ lography that is appropriate mainly to both final-year undergraduate studies in crystallography, chemistry, and chemical physics, and introductory post­ graduate work in this area of crystallography. We believe that the book will be of interest in other disciplines, such as physics, metallurgy, biochemistry, and geology, where crystallography has an important part to play. In the space of one book, it is not possible either to cover all aspects of crystallography or to treat all the subject matter completely rigorously. In particular, certain ...

  16. UV-visible spectroscopy of macrocyclic alkyl, nitrosyl and halide complexes of cobalt and rhodium. Experiment and calculation.

    Science.gov (United States)

    Hull, Emily A; West, Aaron C; Pestovsky, Oleg; Kristian, Kathleen E; Ellern, Arkady; Dunne, James F; Carraher, Jack M; Bakac, Andreja; Windus, Theresa L

    2015-02-28

    Transition metal complexes (NH3)5CoX(2+) (X = CH3, Cl) and L(H2O)MX(2+), where M = Rh or Co, X = CH3, NO, or Cl, and L is a macrocyclic N4 ligand are examined by both experiment and computation to better understand their electronic spectra and associated photochemistry. Specifically, irradiation into weak visible bands of nitrosyl and alkyl complexes (NH3)5CoCH3(2+) and L(H2O)M(III)X(2+) (X = CH3 or NO) leads to photohomolysis that generates the divalent metal complex and ˙CH3 or ˙NO, respectively. On the other hand, when X = halide or NO2, visible light photolysis leads to dissociation of X(-) and/or cis/trans isomerization. Computations show that visible bands for alkyl and nitrosyl complexes involve transitions from M-X bonding orbitals and/or metal d orbitals to M-X antibonding orbitals. In contrast, complexes with X = Cl or NO2 exhibit only d-d bands in the visible, so that homolytic cleavage of the M-X bond requires UV photolysis. UV-Vis spectra are not significantly dependent on the structure of the equatorial ligands, as shown by similar spectral features for (NH3)5CoCH3(2+) and L(1)(H2O)CoCH3(2+).

  17. Thermal behavior of J-aggregates in a Langmuir-Blodgett film of pure merocyanine dye investigated by UV-visible and IR absorption spectroscopy.

    Science.gov (United States)

    Hirano, Yoshiaki; Tateno, Shinsuke; Maio, Ari; Ozaki, Yukihiro

    2009-03-05

    We have characterized the structure of J-aggregate in a Langmuir-Blodgett film of pure merocyanine dye (MS18) fabricated under an aqueous subphase containing a cadmium ion (Cd2+) and have investigated its thermal behavior by UV-visible and IR absorption spectroscopy in the range from 25 to 250 degrees C with a continuous scan. The results of both UV-visible and IR absorption spectra indicate that temperature-dependent changes in the MS18 aggregation state in the pure MS18 system are closely and mildly linked with the MS18 intramolecular charge transfer and the behavior of the packing, orientation, conformation, and thermal mobility of MS18 hydrocarbon chain, respectively. The J-aggregate in the pure MS18 system dissociates from 25 to 150 degrees C, and the dissociation temperature at 150 degrees C is higher by 50 degrees C than that in the previous MS18- arachidic acid (C20) binary system. The lower dissociation temperature in the binary system originates from the fact that temperature-dependent structural disorder of cadmium arachidate (CdC20), being phase-separated from MS18, has an influence on the dissociation of J-aggregate. From 160 to 180 degrees C, thermally induced blue-shifted bands, caused by the oligomeric MS18 aggregation, appear at around 520 nm in the pure MS18 system by contraries, regardless of the lack of driving force by the melting phenomenon of CdC20. The temperature at which the 520 nm bands occur is in good agreement with the melting point (160 degrees C) of hydrocarbon chain in MS18 with Cd2+, whereas its chromophore part is clearly observed to melt near 205 degrees C by UV-visible spectra. Therefore, it is suggested that the driving force that induces the 520 nm band in the pure MS18 system arises from the partial melting of hydrocarbon chain in MS18 with Cd2+.

  18. Real time observation of proteolysis with Fourier transform infrared (FT-IR) and UV-circular dichroism spectroscopy: Watching a protease eat a protein

    Science.gov (United States)

    Güler, Günnur; Džafić, Enela; Vorob'ev, Mikhail M.; Vogel, Vitali; Mäntele, Werner

    2011-06-01

    Fourier transform infrared (FT-IR)- and UV-circular dichroism (UV-CD) spectroscopy have been used to study real-time proteolytic digestion of β-lactoglobulin (β-LG) and β-casein (β-CN) by trypsin at various substrate/enzyme ratios in D 2O-buffer at 37 °C. Both techniques confirm that protein substrate looses its secondary structure upon conversion to the peptide fragments. This perturbation alters the backbone of the protein chain resulting in conformational changes and degrading of the intact protein. Precisely, the most significant spectral changes which arise from digestion take place in the amide I and amide II regions. The FT-IR spectra for the degraded β-LG show a decrease around 1634 cm -1, suggesting a decrease of β-sheet structure in the course of hydrolysis. Similarly, the intensity around the 1654 cm -1 band decreases for β-CN digested by trypsin, indicating a reduction in the α-helical part. On the other hand, the intensity around ˜1594 cm -1 and ˜1406 cm -1 increases upon enzymatic breakdown of both substrates, suggesting an increase in the antisymmetric and symmetric stretching modes of free carboxylates, respectively, as released digestion products. Observation of further H/D exchange in the course of digestion manifests the structural opening of the buried groups and accessibility to the core of the substrate. On the basis of the UV-CD spectra recorded for β-LG and β-CN digested by trypsin, the unordered structure increases concomitant with a decrease in the remaining structure, thus, revealing breakdown of the intact protein into smaller fragments. This model study in a closed reaction system may serve as a basis for the much more complex digestion processes in an open reaction system such as the stomach.

  19. A combined Surface Enhanced Raman Spectroscopy (SERS)/UV-vis approach for the investigation of dye content in commercial felt tip pens inks.

    Science.gov (United States)

    Saviello, Daniela; Trabace, Maddalena; Alyami, Abeer; Mirabile, Antonio; Giorgi, Rodorico; Baglioni, Piero; Iacopino, Daniela

    2018-05-01

    The development of protocols for the protection of the large patrimony of works of art created by felt tip pen media since the 1950's requires detailed knowledge of the main dyes constituting commercial ink mixtures. In this work Surface Enhanced Raman Scattering (SERS) and UV-vis spectroscopy were used for the first time for the systematic identification of dye composition in commercial felt tip pens. A large selection of pens comprising six colors of five different brands was analyzed. Intense SERS spectra were obtained for all colors, allowing identification of main dye constituents. Poinceau 4R and Eosin dyes were found to be the main constituents of red and pink colors; Rhodamine and Tartrazine were found in orange and yellow colors; Erioglaucine was found in green and blue colors. UV-vis analysis of the same inks was used to support SERS findings but also to unequivocally assign some uncertain dye identifications, especially for yellow and orange colors. The spectral data of all felt tip pens collected through this work were assembled in a database format. The data obtained through this systematic investigation constitute the basis for the assembly of larger reference databases that ultimately will support the development of conservation protocols for the long term preservation of modern art collections. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Study of the β-Cyclodextrin Imipramine Hydrochloride Inclusion Complex and Determination of its Stability Constant (K by UV-Visible Spectroscopy

    Directory of Open Access Journals (Sweden)

    Alamdar Ashnagar

    2007-01-01

    Full Text Available In this research, the interactions of imipramine hydrochloride drug with β- cyclodextrin and the stability constant (K of the inclusion complex formed between them were investigated by using UV-visible spectroscopy. Solutions consisting of a known and constant amount of imipramine hydrochloride and varying amounts of β- cyclodextrin were prepared in 0.1 M phosphate buffer (pH 7.4. The final solutions had cyclodextrin concentrations between 0.0011 and 0.0153 M. UV-visible spectra of each solution was taken at λmax= 250 nm. The absorbances at this wavelength were recorded and plotted against cyclodextrin concentrations. From the graph, the concentrations of free and bound imipramine hydrochloride and free β-cyclodextrin were calculated using the Beer-Lambert law. From these data, the stability constant was calculated and a value of K=52.26±11.41 mol-1L was obtained. The magnitude of the stability constant is discussed in terms of the relative sizes and the chemical natures of β-cyclodextrin and imipramine hydrochloride.

  1. Spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules.......This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules....

  2. Self-assembled organic monolayers on gold nanoparticles: A study by sum-frequency generation combined with UV-vis spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Humbert, C. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France) and Laboratoire de Spectroscopie Moleculaire de Surface, University of Namur, 61 Rue de Bruxelles, B-5000 Namur (Belgium)]. E-mail: christophe.humbert@fundp.ac.be; Busson, B. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France); Abid, J.-P. [Ecole Polytechnique Federale de Lausanne, Laboratoire d' Electrochimie Physique et Analytique, CH-1015 Lausanne (Switzerland); Six, C. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France); Girault, H.H. [Ecole Polytechnique Federale de Lausanne, Laboratoire d' Electrochimie Physique et Analytique, CH-1015 Lausanne (Switzerland); Tadjeddine, A. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France)

    2005-05-20

    We use sum-frequency generation spectroscopy (SFG) in the infrared 2800-3000 cm{sup -1} spectral range and UV-vis spectroscopy (transmission) in the 450-650 nm spectral range in order to characterize vibrational and electronic properties of various interfaces composed of organic monolayers adsorbed on gold nanoparticles (AuNPs) with 19 nm average diameter. SFG signal is observed for AuNPs films deposited on glass substrates using the following silane intermediates: 3-(aminopropyl) triethoxysilane and 3-(mercaptopropyl) trimethoxysilane. The density of AuNPs and their aggregates are measured with a scanning electron microscope. For the samples showing a strong well-defined surface plasmon resonance (SPR), we also observe an enhancement of their non-linear optical properties. Furthermore, the SFG measurements show that 1-dodecanethiol films are rather well ordered on specific AuNPs substrates. In this way, the presence of the SFG signal, which comes from both the bulk electronic s-d interband transition and the vibrational states of the adsorbed molecules, depends on a SPR process. This phenomenon is evidenced on the AuNPs by the incident visible beam located at 532 nm, i.e. near the SPR energy maximum of these interfaces. These results open the door to experiments involving macromolecular and biological materials networks deposited on ultrathin metal electrodes in a controlled electrochemical environment.

  3. Self-assembled organic monolayers on gold nanoparticles: A study by sum-frequency generation combined with UV-vis spectroscopy

    International Nuclear Information System (INIS)

    Humbert, C.; Busson, B.; Abid, J.-P.; Six, C.; Girault, H.H.; Tadjeddine, A.

    2005-01-01

    We use sum-frequency generation spectroscopy (SFG) in the infrared 2800-3000 cm -1 spectral range and UV-vis spectroscopy (transmission) in the 450-650 nm spectral range in order to characterize vibrational and electronic properties of various interfaces composed of organic monolayers adsorbed on gold nanoparticles (AuNPs) with 19 nm average diameter. SFG signal is observed for AuNPs films deposited on glass substrates using the following silane intermediates: 3-(aminopropyl) triethoxysilane and 3-(mercaptopropyl) trimethoxysilane. The density of AuNPs and their aggregates are measured with a scanning electron microscope. For the samples showing a strong well-defined surface plasmon resonance (SPR), we also observe an enhancement of their non-linear optical properties. Furthermore, the SFG measurements show that 1-dodecanethiol films are rather well ordered on specific AuNPs substrates. In this way, the presence of the SFG signal, which comes from both the bulk electronic s-d interband transition and the vibrational states of the adsorbed molecules, depends on a SPR process. This phenomenon is evidenced on the AuNPs by the incident visible beam located at 532 nm, i.e. near the SPR energy maximum of these interfaces. These results open the door to experiments involving macromolecular and biological materials networks deposited on ultrathin metal electrodes in a controlled electrochemical environment

  4. Discrimination of Aurantii Fructus Immaturus and Fructus Poniciri Trifoliatae Immaturus by Flow Injection UV Spectroscopy (FIUV) and 1H NMR using Partial Least-squares Discriminant Analysis (PLS-DA)

    Science.gov (United States)

    Two simple fingerprinting methods, flow-injection UV spectroscopy (FIUV) and 1H nuclear magnetic resonance (NMR), for discrimination of Aurantii FructusImmaturus and Fructus Poniciri TrifoliataeImmaturususing were described. Both methods were combined with partial least-squares discriminant analysis...

  5. Genetic engineering combined with deep UV resonance Raman spectroscopy for structural characterization of amyloid-like fibrils.

    Science.gov (United States)

    Sikirzhytski, Vitali; Topilina, Natalya I; Higashiya, Seiichiro; Welch, John T; Lednev, Igor K

    2008-05-07

    Elucidating the structure of the cross-beta core in large amyloid fibrils is a challenging problem in modern structural biology. For the first time, a set of de novo polypeptides was genetically engineered to form amyloid-like fibrils with similar morphology and yet different strand length. Differential ultraviolet Raman spectroscopy allowed for separation of the spectroscopic signatures of the highly ordered beta-sheet strands and turns of the fibril core. The relationship between Raman frequencies and Ramachandran dihedral angles of the polypeptide backbone indicates the nature of the beta-sheet and turn structural elements.

  6. Assessing Pearl Quality Using Reflectance UV-Vis Spectroscopy: Does the Same Donor Produce Consistent Pearl Quality?

    Directory of Open Access Journals (Sweden)

    Paul C. Southgate

    2010-09-01

    Full Text Available Two groups of commercial quality (“acceptable” pearls produced using two donors, and a group of “acceptable” pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected

  7. Electron crystallography of organic pigments

    International Nuclear Information System (INIS)

    Boyce, G.

    1997-10-01

    The principle aim of this thesis is the detailing of the development and subsequent use of electron crystallographic techniques which employ the maximum entropy approach. An account is given of the electron microscope as a crystallographic instrument, along with the necessary theory involved. Also, an overview of the development of electron crystallography, as a whole, is given. This progresses to a description of the maximum entropy methodology and how use can be made of electron diffraction data in ab initio phasing techniques. Details are also given of the utilisation of image derived phases in the determination of structural information. Extensive examples are given of the use of the maximum entropy program MICE, as applied to a variety of structural problems. A particular area of interest covered by this thesis is regarding the solid state structure of organic pigments. A detailed structure review of both β-naphthol and acetoacetanilide pigments was undertaken. Information gained from this review was used as a starting point for the attempted structural elucidation of a related pigment, Barium Lake Red C. Details are given of the synthesis, electron microscope studies and subsequent ab initio phasing procedures applied in the determination of structural information on Barium Lake Red C. The final sections of this thesis detail electron crystallographic analyses of three quite different structures. Common to all was the use of maximum entropy methods, both for ab initio phasing and use of image derived phases. Overall, it is shown that electron crystallographic structure analyses using maximum entropy methods are successful using electron diffraction data and do provide distinct structural information even when significant perturbations to the data exist. (author)

  8. Measurement of the population densities in Gd atomic vapor using diode laser absorption spectroscopy in UV transitions

    International Nuclear Information System (INIS)

    Kwon, Duck Hee; Jung, E. C.; Ko, Kwang Hoon; Kim, Tack Soo

    2003-01-01

    We report on the ultraviolet laser absorption spectroscopy of atomic Gd at 394-554 nm where two transition lines are place very closely by using a frequency-doubled beam of external-cavity diode laser (ECDL). One is from 999.121 to 26337.071 cm -1 and the other from 0 to 25337.755 cm -1 . If two transition lines are placed closely within a continuous fine tuning range, the real-time measurement of the atomic excitation temperature is possible without any significant time consumption because at least two transition lines originating from different low-lying energy levels need to be investigated for the Boltzmann-plot. Since the spectral difference between the two transitions is only about 0.195 cm -1 (5.85 GHz), it is possible to record both the absorption spectra simultaneously as shown in Fig. 1. But the transition probabilities (or oscillator strengths) of these lines have not been measured accurately yet to the best of our knowledge. We report on the newly measured transition probabilities by analyzing their absorption spectra at known vapor density conditions. The simultaneous measurement of the atomic excitation temperature and the vapor density demonstrated. In addition we present another ultraviolet laser absorption spectroscopy of atomic Gd at 403.540 nm by means of a commercial blue diode laser and investigate the characteristics of the blue diode laser as well.

  9. Sensitive determination of trace mercury by UV-visible diffuse reflectance spectroscopy after complexation and membrane filtration-enrichment.

    Science.gov (United States)

    Yin, Changhai; Iqbal, Jibran; Hu, Huilian; Liu, Bingxiang; Zhang, Lei; Zhu, Bilin; Du, Yiping

    2012-09-30

    A simple, sensitive and selective solid phase reflectometry method is proposed for the determination of trace mercury in aqueous samples. The complexation reagent dithizone was firstly injected into the properly buffered solution with vigorous stirring, which started a simultaneous formation of nanoparticles suspension of dithizone and its complexation reaction with the mercury(II) ions to make Hg-dithizone nanoparticles. After a definite time, the mixture was filtered with membrane, and then quantified directly on the surface of the membrane by using integrating sphere accessory of the UV-visible spectrophotometer. The quantitative analysis was carried out at a wavelength of 485 nm since it yielded the largest difference in diffuse reflectance spectra before and after reaction with mercury(II).A good linear correlation in the range of 0.2-4.0 μg/L with a squared correlation coefficient (R(2)) of 0.9944 and a detection limit of 0.12 μg/L were obtained. The accuracy of the method was evaluated by the analysis of spiked mercury(II) concentrations determined using this method along with those determined by the atomic fluorescence mercury vapourmeter and the results obtained were in good agreement. The proposed method was applied to the determination of mercury in tap water and river water samples with the recovery in an acceptable range (95.7-105.3%). Copyright © 2012 Elsevier B.V. All rights reserved.

  10. spectroscopy

    African Journals Online (AJOL)

    Aghomotsegin

    2015-10-14

    Oct 14, 2015 ... characterized by using phenotypic, API and Fourier transform infrared (FTIR) spectroscopy methods. One hundred and fifty-seven (157) strains were isolated from 13 cheese samples, and identification test was performed for 83 strains. At the end of the study, a total of 22 Lactococcus sp., 36 Enterecoccus ...

  11. Effect of flavin compounds on uranium(VI) reduction- kinetic study using electrochemical methods with UV-vis spectroscopy

    International Nuclear Information System (INIS)

    Yamasaki, Shinya; Tanaka, Kazuya; Kozai, Naofumi; Ohnuki, Toshihiko

    2017-01-01

    The reduction of uranium hexavalent (U(VI)) to tetravalent (U(IV)) is an important reaction because of the change in its mobility in the natural environment. Although the flavin mononucleotide (FMN) has acted as an electron shuttle for the U(VI) reduction in vivo system, which is called an electron mediator, only the rate constant for the electron transfer from FMN to U(VI) has been determined. This study examined the rate constant for the U(VI) reduction process by three flavin analogues (riboflavin, flavin mononucleotide, flavin adenine dinucleotide) to elucidate their substituent group effect on the U(VI) reduction rate by electrochemical methods. The formation of the U(IV) was monitored by UV-vis spectrometry at 660 nm during the constant potential electrolysis of the U(VI) solution in the presence of the mediator. The cyclic voltammograms indicated that the three flavin analogues behaved as electron mediator to reduce U(VI). The logarithmic rate constant for the U(VI) reduction was related to the standard redox potential of the mediators. This linear relationship indicated that the redox-active group of the mediator and the substituent group of the mediator dominate capability of the U(VI) reduction and its rate, respectively. The apparent reduction potential of U(VI) increased about 0.2 V in the presence of the mediators, which strongly suggests that the biological electron mediator makes the U(VI) reduction possible even under more oxidative conditions. - Highlights: • The rate constant for the U(VI) reduction by flavin analogues was determined. • The flavins showed a mediator effect on the U(VI) reduction. • The logarithmic rate constants for the U(VI) reduction was proportional to redox potential of the mediator. • The presence of the mediator increased about 0.2 V apparent redox potential of U(VI) to U(IV).

  12. Reliable TLDA-microvolume UV spectroscopy with applications in chemistry and biosciences for microlitre analysis and rapid pipette calibration

    Science.gov (United States)

    McMillan, Norman; O'Neill, Martina; Smith, Stephen; Hammond, John; Riedel, Sven; Arthure, Kevin; Smith, S.

    2009-05-01

    A TLDA-microvolume (transmitted light drop analyser) accessory for use with a standard UV-visible fibre spectrophotometer is described. The physics of the elegantly simple optical design is described along with the experimental testing of this accessory. The modelling of the arrangement is fully explored to investigate the performance of the drop spectrophotometer. The design optimizes the focusing to deliver the highest quality spectra, rapid and simple sample handling and, importantly, no detectable carryover on the single quartz drophead. Results of spectral measurements in a laboratory providing NIST standards show the closest correlation between modelled pathlength and experimental measurement for different drop volumes in the range 0.7-3 µl. This instrument accessory delivers remarkably accurate and reproducible results that are good enough to allow the accessory to be used for rapid pipette calibration to avoid the laborious weighing methods currently employed. Measurements on DNA standards and proteins are given to illustrate the main application area of biochemistry for this accessory. The accessory has a measurement range of at least 0-60 A units without sample dilution and, since there exists an accurate volume-pathlength relationship, the drop volume used in any specific measurement or assay should be optimized to minimize the photometric error. Studies demonstrate that the cleaning of the drophead with lab wipes results in no measurable carryover. This important practical result is confirmed from direct reading of the accessory and an analytical balance which was used to perform carryover studies. For further information on the TLDA please contact: Drop Technology, Unit 2, Tallaght Business Park, Whitestown, Dublin 24, Republic of Ireland. email: info@droptechnology.com.

  13. Improved selectivity for Pb(II) by sulfur, selenium and tellurium analogues of 1,8-anthraquinone-18-crown-5: synthesis, spectroscopy, X-ray crystallography and computational studies.

    Science.gov (United States)

    Mariappan, Kadarkaraisamy; Alaparthi, Madhubabu; Hoffman, Mariah; Rama, Myriam Alcantar; Balasubramanian, Vinothini; John, Danielle M; Sykes, Andrew G

    2015-07-14

    We report here a series of heteroatom-substituted macrocycles containing an anthraquinone moiety as a fluorescent signaling unit and a cyclic polyheteroether chain as the receptor. Sulfur, selenium, and tellurium derivatives of 1,8-anthraquinone-18-crown-5 (1) were synthesized by reacting sodium sulfide (Na2S), sodium selenide (Na2Se) and sodium telluride (Na2Te) with 1,8-bis(2-bromoethylethyleneoxy)anthracene-9,10-dione in a 1 : 1 ratio. The optical properties of the new compounds are examined and the sulfur and selenium analogues produce an intense green emission enhancement upon association with Pb(II) in acetonitrile. Selectivity for Pb(II) is markedly improved as compared to the oxygen analogue 1 which was also competitive for Ca(II) ion. UV-Visible and luminescence titrations reveal that 2 and 3 form 1 : 1 complexes with Pb(II), confirmed by single-crystal X-ray studies where Pb(II) is complexed within the macrocycle through coordinate covalent bonds to neighboring carbonyl, ether and heteroether donor atoms. Cyclic voltammetry of 2-8 showed classical, irreversible oxidation potentials for sulfur, selenium and tellurium heteroethers in addition to two one-electron reductions for the anthraquinone carbonyl groups. DFT calculations were also conducted on 1, 2, 3, 6, 6 + Pb(II) and 6 + Mg(II) to determine the trend in energies of the HOMO and the LUMO levels along the series.

  14. Application of multi-way analysis to UV-visible spectroscopy, gas chromatography and electronic nose data for wine ageing evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, N. [Department of Condensed Matter Physics, Faculty of Sciences, University of Valladolid, 47011 Valladolid (Spain); Department of Inorganic Chemistry, Escuela de Ingenierias Industriales, University of Valladolid, Paseo del Cauce, 59, 47011 Valladolid (Spain); Rodriguez-Mendez, M.L. [Department of Inorganic Chemistry, Escuela de Ingenierias Industriales, University of Valladolid, Paseo del Cauce, 59, 47011 Valladolid (Spain); Leardi, R. [Department of Pharmaceutical and Food Chemistry and Technology, University of Genoa, Via Brigata Salerno 13, I-16147 8 Genoa (Italy); Oliveri, P., E-mail: oliveri@dictfa.unige.it [Department of Pharmaceutical and Food Chemistry and Technology, University of Genoa, Via Brigata Salerno 13, I-16147 8 Genoa (Italy); Hernando-Esquisabel, D.; Iniguez-Crespo, M. [Gobierno de la Rioja, Consejeria de Agricultura y Alimentacion, Estacion Enologica, Breton de los Herreros 4, 26200 Haro, La Rioja (Spain); Saja, J.A. de [Department of Condensed Matter Physics, Faculty of Sciences, University of Valladolid, 47011 Valladolid (Spain)

    2012-03-16

    Highlights: Black-Right-Pointing-Pointer Wine samples were analytically characterised according to their ageing process. Black-Right-Pointing-Pointer Signals from a sensor-based electronic nose were fused with GC-MS and UV-visible data. Black-Right-Pointing-Pointer The study involved 6 periodical determinations of 20 variables on 6 different wines. Black-Right-Pointing-Pointer Multi-way analysis allowed to efficiently extract the maximum information from data. Black-Right-Pointing-Pointer Multi-way methods represent the most suitable tool for processing three-mode data. - Abstract: In this study, a multi-way method (Tucker3) was applied to evaluate the performance of an electronic nose for following the ageing of red wines. The odour evaluation carried out with the electronic nose was combined with the quantitative analysis of volatile composition performed by GC-MS, and colour characterisation by UV-visible spectroscopy. Thanks to Tucker3, it was possible to understand connections among data obtained from these three different systems and to estimate the effect of different sources of variability on wine evaluation. In particular, the application of Tucker3 supplied a global visualisation of data structure, which was very informative to understand relationships between sensors responses and chemical composition of wines. The results obtained indicate that the analytical methods employed are useful tools to follow the wine ageing process, to differentiate wine samples according to ageing type (either in barrel or in stainless steel tanks with the addition of small oak wood pieces) and to the origin (French or American) of the oak wood. Finally, it was possible to designate the volatile compounds which play a major role in such a characterisation.

  15. Insights into the Activity and Deactivation of the Methanol-to-Olefins Process over Different Small-Pore Zeolites As Studied with Operando UV-vis Spectroscopy.

    Science.gov (United States)

    Goetze, Joris; Meirer, Florian; Yarulina, Irina; Gascon, Jorge; Kapteijn, Freek; Ruiz-Martínez, Javier; Weckhuysen, Bert M

    2017-06-02

    The nature and evolution of the hydrocarbon pool (HP) species during the Methanol-to-Olefins (MTO) process for three small-pore zeolite catalysts, with a different framework consisting of large cages interconnected by small eight-ring windows (CHA, DDR, and LEV) was studied at reaction temperatures between 350 and 450 °C using a combination of operando UV-vis spectroscopy and online gas chromatography. It was found that small differences in cage size, shape, and pore structure of the zeolite frameworks result in the generation of different hydrocarbon pool species. More specifically, it was found that the large cage of CHA results in the formation of a wide variety of hydrocarbon pool species, mostly alkylated benzenes and naphthalenes. In the DDR cage, 1-methylnaphthalene is preferentially formed, while the small LEV cage generally contains fewer hydrocarbon pool species. The nature and evolution of these hydrocarbon pool species was linked with the stage of the reaction using a multivariate analysis of the operando UV-vis spectra. In the 3-D pore network of CHA, the reaction temperature has only a minor effect on the performance of the MTO catalyst. However, for the 2-D pore networks of DDR and LEV, an increase in the applied reaction temperature resulted in a dramatic increase in catalytic activity. For all zeolites in this study, the role of the hydrocarbon species changes with reaction temperature. This effect is most clear in DDR, in which diamantane and 1-methylnaphthalene are deactivating species at a reaction temperature of 350 °C, whereas at higher temperatures diamantane formation is not observed and 1-methylnaphthalene is an active species. This results in a different amount and nature of coke species in the deactivated catalyst, depending on zeolite framework and reaction temperature.

  16. FT-IR, FT-Raman, UV-visible, and NMR spectroscopy and vibrational properties of the labdane-type diterpene 13-epi-sclareol.

    Science.gov (United States)

    Chain, Fernando E; Leyton, Patricio; Paipa, Carolina; Fortuna, Mario; Brandán, Silvia A

    2015-03-05

    In this work, FT-IR, FT-Raman, UV-Visible and NMR spectroscopies and density functional theory (DFT) calculations were employed to study the structural and vibrational properties of the labdane-type diterpene 13-epi-sclareol using the hybrid B3LYP method together with the 6-31G(∗) basis set. Three stable structures with minimum energy found on the potential energy curves (PES) were optimized, and the corresponding molecular electrostatic potentials, atomic charges, bond orders, stabilization energies and topological properties were computed at the same approximation level. The complete assignment of the bands observed in the vibrational spectrum of 13-epi-sclareol was performed taking into account the internal symmetry coordinates for the three structures using the scaled quantum mechanical force field (SQMFF) methodology at the same level of theory. In addition, the force constants were calculated and compared with those reported in the literature for similar compounds. The predicted vibrational spectrum and the calculated (1)H NMR and (13)C NMR chemical shifts are in good agreement with the corresponding experimental results. The theoretical UV-Vis spectra for the most stable structure of 13-epi-sclareol demonstrate a better correlation with the corresponding experimental spectrum. The study of the three conformers by means of the theory of atoms in molecules (AIM) revealed different H bond interactions and a strong dependence of the interactions on the distance between the involved atoms. Furthermore, the natural bond orbital (NBO) calculations showed the characteristics of the electronic delocalization for the two six-membered rings with chair conformations. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. In situ macromolecular crystallography using microbeams.

    Science.gov (United States)

    Axford, Danny; Owen, Robin L; Aishima, Jun; Foadi, James; Morgan, Ann W; Robinson, James I; Nettleship, Joanne E; Owens, Raymond J; Moraes, Isabel; Fry, Elizabeth E; Grimes, Jonathan M; Harlos, Karl; Kotecha, Abhay; Ren, Jingshan; Sutton, Geoff; Walter, Thomas S; Stuart, David I; Evans, Gwyndaf

    2012-05-01

    Despite significant progress in high-throughput methods in macromolecular crystallography, the production of diffraction-quality crystals remains a major bottleneck. By recording diffraction in situ from crystals in their crystallization plates at room temperature, a number of problems associated with crystal handling and cryoprotection can be side-stepped. Using a dedicated goniometer installed on the microfocus macromolecular crystallography beamline I24 at Diamond Light Source, crystals have been studied in situ with an intense and flexible microfocus beam, allowing weakly diffracting samples to be assessed without a manual crystal-handling step but with good signal to noise, despite the background scatter from the plate. A number of case studies are reported: the structure solution of bovine enterovirus 2, crystallization screening of membrane proteins and complexes, and structure solution from crystallization hits produced via a high-throughput pipeline. These demonstrate the potential for in situ data collection and structure solution with microbeams. © 2012 International Union of Crystallography

  18. Comparative study of nuclear magnetic resonance and UV-visible spectroscopy dose-response of polymer gel based on N-(Isobutoxymethyl) acrylamide

    Science.gov (United States)

    Lotfy, S.; Basfar, A. A.; Moftah, B.; Al-Moussa, A. A.

    2017-12-01

    A comparative study of nuclear magnetic resonance and UV-visible spectroscopy of dose-response for polymer gel dosimeters was performed. Dosimeters were prepared using N-(Isobutoxymethyl) acrylamide (NIBMA) as a new monomer via radiation induced polymerization for use in radiotherapy planning. The prepared dosimeters were irradiated with doses up to 30 Gy at a constant dose rate of 600 MU/min. Using a medical linear accelerator at irradiation energies of 6, 10 and 18 MV photon beam. The nuclear magnetic resonance (NMR), via spin-spin relaxation rate (R2) for water proton surrounding the polymer formulation and UV-Visible spectroscopy, via the optical absorbance measurements of irradiated dosimeters at selected wavelengths of 500 nm, was used to investigate the dose response of NIBMAGAT gel dosimeters. Scavenge of oxygen was done using tetrakis (hydroxymethyl) phosphonium chloride (THPC). The THPC optimum concentration in the dosimeters formulations were 5 and 10 mM for the NMR and optical absorbance measurements respectively. The quantitative investigation of the dosimeters components reveals the selective formulations based on 4% w/w gelatin, 1% w/w NIBMA, 3% w/w BisAAm, 5 or 10 mM THPC and 17% w/w glycerol which significantly increase the dosimeters dose response. The prepared dosimeters were found to be dose rate and photon beam irradiation energy independent. The stability study shows no change in the relaxation rate or in the optical absorbance of the gel dosimeters up to 8 days post-irradiation. The prepared polymer gel dosimeters at the energies of 6, 10 and 18 MV photon beam irradiation in the range of 1-30 Gy have the linearity of the dose response function in the case of R2 is better than in the case of absorbance measurements; correlation coefficient (r2) equals 0.995 and 0.991, respectively. Dose sensitivity, R2 of NIBMAGAT dosimeters (0.0775 s-1 Gy-1). The absorption band intensity increases linearly with a dose sensitivity of 0.016 cm-1 Gy-1. The

  19. Crystallography of quasicrystals concepts, methods and structures

    CERN Document Server

    Walter, Steurer

    2009-01-01

    From tilings to quasicrystal structures and from surfaces to the n-dimensional approach, this book gives a full, self-contained in-depth description of the crystallography of quasicrystals. It aims not only at conveying the concepts and a precise picture of the structures of quasicrystals, butit also enables the interested reader to enter the field of quasicrystal structure analysis. Going beyond metallic quasicrystals, it also describes the new, dynamically growing field of photonic quasicrystals. The readership will be graduate students and researchers in crystallography, solid-state physics, materials science, solid- state chemistry and applied mathematics.

  20. History of protein crystallography in China

    OpenAIRE

    Rao, Zihe

    2007-01-01

    China has a strong background in X-ray crystallography dating back to the 1920s. Protein crystallography research in China was first developed following the successful synthesis of insulin in China in 1966. The subsequent determination of the three-dimensional structure of porcine insulin made China one of the few countries which could determine macromolecular structures by X-ray diffraction methods in the late 1960s and early 1970s. After a slow period during the 1970s and 1980s, protein cry...

  1. Self-association of caffeine in aqueous solution. Study of dilute solutions by normal and second derivative UV absorption spectroscopy.

    Science.gov (United States)

    Iza, N.; Gil, M.; Montero, J. L.; Morcillo, J.

    1988-05-01

    The concentration dependence of the spectral parameters of caffeine bands at ˜205 and 273 nm has been studied in aqueous solution by normal and second derivative spectroscopy. The concentration range was 5 x 10 -6 - 5 x 10 -3 M and thirty-five different concentrations were used. Discontinuities in parameter variation of these two bands at ˜7.5 x 10 -5, ˜2 x 10 -4, and ˜1 x 10 -3M were observed as concentration was increased. These "limiting" concentrations define three quite differenciated hyper- or hipochromic effects: the first one can be explained as caffeine-water molecule interaction and the second and third as dimer and (dimer + polymer) stacking, respectively. Apparent self-association constants using the isodesmic model have been obtained K= 160 M -1 (for the second hypochromic effect) and K= 13.6 M -1 (for the third hypochromic effect), for the 273 nm band. It is noteworthy that the three "limiting" concentrations coincide with changes in DNA-caffeine interaction modes (H. Lang , 1976) and biological activity (I.B. Syed , 1976).

  2. Investigation on LPCVD SiON films by means of Rutherford backscattering, FT-IR and UV-VIS Spectroscopy

    International Nuclear Information System (INIS)

    Dudu, D.; Ivanov, E.; Bercu, B.N.; Bercu, M.; Modreanu, M.

    2003-01-01

    The SiON layers deposited by LPCVD (Low Vapour Chemical Deposition ) on Si (111) substrate has been investigated by complementary techniques as Rutherford backscattering and optical spectroscopy. We have determined the evolution of chemical content in respect with oxygen relative to nitrogen. The change in oxygen content versus time was produced by exposing the sample in wet oxygen at 1000 deg. C for different periods. The change in oxygen amount was determined by monitoring the Si-O-Si integral intensity of the absorption band at 1071cm -1 . Also the behavior of the refractive index versus time in an oxidative atmosphere gave a complementary information about the oxygen content. Alpha scattering spectra obtained by means of cyclotron facilities was used as another technique for oxygen to nitrogen ratio determination. Both visible spectra and RBS data were fitted by using the corresponding simulating approaches based on light propagation in non-homogeneous media and respectively on multiple scattering theory. The time evolution of O content indicated a diffused controlled process through the gas/solid interface. (authors)

  3. Direct spectral analysis and determination of high content of carcinogenic bromine in bread using UV pulsed laser induced breakdown spectroscopy.

    Science.gov (United States)

    Mehder, A O; Gondal, Mohammed A; Dastageer, Mohamed A; Habibullah, Yusuf B; Iqbal, Mohammed A; Oloore, Luqman E; Gondal, Bilal

    2016-01-01

    Laser induced breakdown spectroscopy (LIBS) was applied for the detection of carcinogenic elements like bromine in four representative brands of loaf bread samples and the measured bromine concentrations were 352, 157, 451, and 311 ppm, using Br I (827.2 nm) atomic transition line as the finger print atomic transition. Our LIBS system is equipped with a pulsed laser of wavelength 266 nm with energy 25 mJ pulse(-1), 8 ns pulse duration, 20 Hz repetition rate, and a gated ICCD camera. The LIBS system was calibrated with the standards of known concentrations in the sample (bread) matrix and such plot is linear in 20-500 ppm range. The capability of our system in terms of limit of detection and relative accuracy with respect to the standard inductively coupled plasma mass spectrometry (ICPMS) technique was evaluated and these values were 5.09 ppm and 0.01-0.05, respectively, which ensures the applicability of our system for Br trace level detection, and LIBS results are in excellent agreement with that of ICPMS results.

  4. Isomer-specific detection in the UV photodissociation of the propargyl radical by chirped-pulse mm-wave spectroscopy in a pulsed quasi-uniform flow.

    Science.gov (United States)

    Broderick, Bernadette M; Suas-David, Nicolas; Dias, Nureshan; Suits, Arthur G

    2018-02-21

    Isomer-specific detection and product branching fractions in the UV photodissociation of the propargyl radical is achieved through the use of chirped-pulse Fourier-transform mm-wave spectroscopy in a pulsed quasi-uniform flow (CPUF). Propargyl radicals are produced in the 193 nm photodissociation of 1,2-butadiene. Absorption of a second photon leads to H atom elimination giving three possible C 3 H 2 isomers: singlets cyclopropenylidene (c-C 3 H 2 ) and propadienylidene (l-C 3 H 2 ), and triplet propargylene ( 3 HCCCH). The singlet products and their appearance kinetics in the flow are directly determined by rotational spectroscopy, but due to the negligible dipole moment of propargylene, it is not directly monitored. However, we exploit the time-dependent kinetics of H-atom catalyzed isomerization to infer the branching to propargylene as well. We obtain the overall branching among H loss channels to be 2.9% (+1.1/-0.5) l-C 3 H 2 + H, 16.8% (+3.2/-1.3) c-C 3 H 2 + H, and 80.2 (+1.8/-4.2) 3 HCCCH + H. Our findings are qualitatively consistent with earlier RRKM calculations in that the major channel in the photodissociation of the propargyl radical at 193 nm is to 3 HCCCH + H; however, a greater contribution to the energetically most favorable isomer, c-C 3 H 2 + H is observed in this work. We do not detect the predicted HCCC + H 2 channel, but place an upper bound on its yield of 1%.

  5. Pharmaceutical crystallography: is there a devil in the details?

    DEFF Research Database (Denmark)

    Bond, A. D.

    2012-01-01

    Modern instruments for small-molecule crystallography continue to become more sophisticated and more automated. This technical progress provides a basis for frontier research in chemical and pharmaceutical crystallography, but it also encourages analytical crystallographers to become more...... are presented for pharmaceutical compounds, and the potential importance of the "details" in pharmaceutical crystallography is discussed....

  6. Online Monitoring of Water-Quality Anomaly in Water Distribution Systems Based on Probabilistic Principal Component Analysis by UV-Vis Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Dibo Hou

    2014-01-01

    Full Text Available This study proposes a probabilistic principal component analysis- (PPCA- based method for online monitoring of water-quality contaminant events by UV-Vis (ultraviolet-visible spectroscopy. The purpose of this method is to achieve fast and sound protection against accidental and intentional contaminate injection into the water distribution system. The method is achieved first by properly imposing a sliding window onto simultaneously updated online monitoring data collected by the automated spectrometer. The PPCA algorithm is then executed to simplify the large amount of spectrum data while maintaining the necessary spectral information to the largest extent. Finally, a monitoring chart extensively employed in fault diagnosis field methods is used here to search for potential anomaly events and to determine whether the current water-quality is normal or abnormal. A small-scale water-pipe distribution network is tested to detect water contamination events. The tests demonstrate that the PPCA-based online monitoring model can achieve satisfactory results under the ROC curve, which denotes a low false alarm rate and high probability of detecting water contamination events.

  7. A screening method based on UV-Visible spectroscopy and multivariate analysis to assess addition of filler juices and water to pomegranate juices.

    Science.gov (United States)

    Boggia, Raffaella; Casolino, Maria Chiara; Hysenaj, Vilma; Oliveri, Paolo; Zunin, Paola

    2013-10-15

    Consumer demand for pomegranate juice has considerably grown, during the last years, for its potential health benefits. Since it is an expensive functional food, cheaper fruit juices addition (i.e., grape and apple juices) or its simple dilution, or polyphenols subtraction are deceptively used. At present, time-consuming analyses are used to control the quality of this product. Furthermore these analyses are expensive and require well-trained analysts. Thus, the purpose of this study was to propose a high-speed and easy-to-use shortcut. Based on UV-VIS spectroscopy and chemometrics, a screening method is proposed to quickly screening some common fillers of pomegranate juice that could decrease the antiradical scavenging capacity of pure products. The analytical method was applied to laboratory prepared juices, to commercial juices and to representative experimental mixtures at different levels of water and filler juices. The outcomes were evaluated by means of multivariate exploratory analysis. The results indicate that the proposed strategy can be a useful screening tool to assess addition of filler juices and water to pomegranate juices. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Application of multi-way analysis to UV-visible spectroscopy, gas chromatography and electronic nose data for wine ageing evaluation.

    Science.gov (United States)

    Prieto, N; Rodriguez-Méndez, M L; Leardi, R; Oliveri, P; Hernando-Esquisabel, D; Iñiguez-Crespo, M; de Saja, J A

    2012-03-16

    In this study, a multi-way method (Tucker3) was applied to evaluate the performance of an electronic nose for following the ageing of red wines. The odour evaluation carried out with the electronic nose was combined with the quantitative analysis of volatile composition performed by GC-MS, and colour characterisation by UV-visible spectroscopy. Thanks to Tucker3, it was possible to understand connections among data obtained from these three different systems and to estimate the effect of different sources of variability on wine evaluation. In particular, the application of Tucker3 supplied a global visualisation of data structure, which was very informative to understand relationships between sensors responses and chemical composition of wines. The results obtained indicate that the analytical methods employed are useful tools to follow the wine ageing process, to differentiate wine samples according to ageing type (either in barrel or in stainless steel tanks with the addition of small oak wood pieces) and to the origin (French or American) of the oak wood. Finally, it was possible to designate the volatile compounds which play a major role in such a characterisation. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Effect of pH on the chemical modification of quercetin and structurally related flavonoids characterized by optical (UV-visible and Raman) spectroscopy.

    Science.gov (United States)

    Jurasekova, Z; Domingo, C; Garcia-Ramos, J V; Sanchez-Cortes, S

    2014-07-07

    In this work we report the study of the chemical modifications undergone by flavonoids, especially by quercetin (QUC), under alkaline conditions by UV-visible absorption, Raman and surface-enhanced Raman scattering (SERS) spectroscopy, the study was performed in aqueous solution and also on Ag nanoparticles (AgNPs). Several processes are involved in the effect of alkaline pH both in solution and on AgNPs: autoxidation affecting mainly the C-ring of the molecule and giving rise to the molecular fragmentation leading to simpler molecular products, and/or the dimerization and further polymerization leading to species with a higher molecular weight. In addition, there exists a clear structure-instability correlation concerning mainly particular groups in the molecule: the C3-OH group in the C-ring, the catechol moiety in the B-ring and the C2=C3 bond also existing in the C-ring. QUC possesses all these groups and exhibits high instability in alkaline solution. The SERS spectra registered at different pH revealed a change in the dimerization protocol of QUC going from the A- and C-rings-like-condensation to B-ring-like-condensation. Increasing the knowledge of the chemical properties of these compounds and determining the structure-activity relationship under specific environmental factors allow us to improve their beneficial properties for health as well as the preservation of Cultural Heritage objects, for example, by preventing their degradation.

  10. Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy

    Science.gov (United States)

    Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

    2018-04-01

    This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2 kV and a power supply system equipped with 25/50 μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp3/sp2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp3/sp2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed.

  11. Study of the phase transformation of single particles of Ga2O3 by UV-Raman spectroscopy and high-resolution TEM.

    Science.gov (United States)

    Wang, Xiang; Xu, Qian; Fan, Fengtao; Wang, Xiuli; Li, Mingrun; Feng, Zhaochi; Li, Can

    2013-09-01

    By taking advantage of UV-Raman spectroscopy and high-resolution TEM (HRTEM), combined with the focused ion beam (FIB) technique, the transformation from GaOOH into α-Ga2O3 and then into β-Ga2O3 was followed. We found that the stepwise transformations took place from the surface region before developing into the bulk of single particles without particle agglomeration and growth. During the transformation from GaOOH into α-Ga2O3, the elimination of water vapor through the dehydroxylation of GaOOH resulted in the formation of micropores in the single particles, whilst maintaining their particle size. For the phase transformation from α-Ga2O3 into β-Ga2O3, the nucleation of β-Ga2O3 was found to occur at the surface defects and this process could be retarded by occupying these defects with a small amount of La2O3. By finely controlling the process of the phase transformation, the β-Ga2O3 domains gradually developed from the surface into the bulk of the single particles without particle agglomeration. Therefore, the surface structure of the α-Ga2O3 single particles can be easily tuned and a particle with an α@β core-shell phase structure has been obtained. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy.

    Science.gov (United States)

    Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

    2018-04-05

    This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp 3 /sp 2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp 3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp 3 /sp 2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp 3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Unprecedented access of phenolic substrates to the heme active site of a catalase: substrate binding and peroxidase-like reactivity of Bacillus pumilus catalase monitored by X-ray crystallography and EPR spectroscopy.

    Science.gov (United States)

    Loewen, Peter C; Villanueva, Jacylyn; Switala, Jacek; Donald, Lynda J; Ivancich, Anabella

    2015-05-01

    Heme-containing catalases and catalase-peroxidases catalyze the dismutation of hydrogen peroxide as their predominant catalytic activity, but in addition, individual enzymes support low levels of peroxidase and oxidase activities, produce superoxide, and activate isoniazid as an antitubercular drug. The recent report of a heme enzyme with catalase, peroxidase and penicillin oxidase activities in Bacillus pumilus and its categorization as an unusual catalase-peroxidase led us to investigate the enzyme for comparison with other catalase-peroxidases, catalases, and peroxidases. Characterization revealed a typical homotetrameric catalase with one pentacoordinated heme b per subunit (Tyr340 being the axial ligand), albeit in two orientations, and a very fast catalatic turnover rate (kcat  = 339,000 s(-1) ). In addition, the enzyme supported a much slower (kcat  = 20 s(-1) ) peroxidatic activity utilizing substrates as diverse as ABTS and polyphenols, but no oxidase activity. Two binding sites, one in the main access channel and the other on the protein surface, accommodating pyrogallol, catechol, resorcinol, guaiacol, hydroquinone, and 2-chlorophenol were identified in crystal structures at 1.65-1.95 Å. A third site, in the heme distal side, accommodating only pyrogallol and catechol, interacting with the heme iron and the catalytic His and Arg residues, was also identified. This site was confirmed in solution by EPR spectroscopy characterization, which also showed that the phenolic oxygen was not directly coordinated to the heme iron (no low-spin conversion of the Fe(III) high-spin EPR signal upon substrate binding). This is the first demonstration of phenolic substrates directly accessing the heme distal side of a catalase. © 2015 Wiley Periodicals, Inc.

  14. Automated data collection for macromolecular crystallography.

    Science.gov (United States)

    Winter, Graeme; McAuley, Katherine E

    2011-09-01

    An overview, together with some practical advice, is presented of the current status of the automation of macromolecular crystallography (MX) data collection, with a focus on MX beamlines at Diamond Light Source, UK. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. The Beginnings of X-ray Crystallography

    Indian Academy of Sciences (India)

    IAS Admin

    significant change in his career came in 1904 when he gave a talk at Dunedin on ... In his personal reminiscences, W L Bragg talks about his school days in Australia. ... two Braggs on the occasion of the International Year of Crystallography .

  16. Special issue on Chemical Crystallography Editorial

    Indian Academy of Sciences (India)

    Virtually, every invitation that we extended has translated into an article. We sincerely believe and wish that the collection of articles in this issue sufficiently showcases the panorama of chemical science involving X-ray crystallography in India. We note with pride that Prof. Gautam R. Desiraju, an eminent scientist who has.

  17. Optimizing the Recognition of Surface Crystallography

    Czech Academy of Sciences Publication Activity Database

    Frank, Luděk; Mika, Filip; Müllerová, Ilona

    2015-01-01

    Roč. 21, S4 (2015), s. 124-129 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : surface crystallography Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

  18. Simple and ultra-fast recognition and quantitation of compounded monoclonal antibodies: Application to flow injection analysis combined to UV spectroscopy and matching method.

    Science.gov (United States)

    Jaccoulet, E; Schweitzer-Chaput, A; Toussaint, B; Prognon, P; Caudron, E

    2018-09-01

    Compounding of monoclonal antibody (mAbs) constantly increases in hospital. Quality control (QC) of the compounded mAbs based on quantification and identification is required to prevent potential errors and fast method is needed to manage outpatient chemotherapy administration. A simple and ultra-fast (less than 30 s) method using flow injection analysis associated to least square matching method issued from the analyzer software was performed and evaluated for the routine hospital QC of three compounded mAbs: bevacizumab, infliximab and rituximab. The method was evaluated through qualitative and quantitative parameters. Preliminary analysis of the UV absorption and second derivative spectra of the mAbs allowed us to adapt analytical conditions according to the therapeutic range of the mAbs. In terms of quantitative QC, linearity, accuracy and precision were assessed as specified in ICH guidelines. Very satisfactory recovery was achieved and the RSD (%) of the intermediate precision were less than 1.1%. Qualitative analytical parameters were also evaluated in terms of specificity, sensitivity and global precision through a matrix of confusion. Results showed to be concentration and mAbs dependant and excellent (100%) specificity and sensitivity were reached within specific concentration range. Finally, routine application on "real life" samples (n = 209) from different batch of the three mAbs complied with the specifications of the quality control i.e. excellent identification (100%) and ± 15% of targeting concentration belonging to the calibration range. The successful use of the combination of second derivative spectroscopy and partial least square matching method demonstrated the interest of FIA for the ultra-fast QC of mAbs after compounding using matching method. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. [Raman spectroscopy applied to analytical quality control of injectable drugs: analytical evaluation and comparative economic versus HPLC and UV / visible-FTIR].

    Science.gov (United States)

    Bourget, P; Amin, A; Vidal, F; Merlette, C; Troude, P; Corriol, O

    2013-09-01

    In France, central IV admixture of chemotherapy (CT) treatments at the hospital is now required by law. We have previously shown that the shaping of Therapeutic Objects (TOs) could profit from an Analytical Quality Assurance (AQA), closely linked to the batch release, for the three key parameters: identity, purity, and initial concentration of the compound of interest. In the course of recent and diversified works, we showed the technical superiority of non-intrusive Raman Spectroscopy (RS) vs. any other analytical option and, especially for both HPLC and vibrational method using a UV/visible-FTIR coupling. An interconnected qualitative and economic assessment strongly helps to enrich these relevant works. The study compares in operational situation, the performance of three analytical methods used for the AQC of TOs. We used: a) a set of evaluation criteria, b) the depreciation tables of the machinery, c) the cost of disposables, d) the weight of equipment and technical installations, e) the basic accounting unit (unit of work) and its composite costs (Euros), which vary according to the technical options, the weight of both human resources and disposables; finally, different combinations are described. So, the unit of work can take 12 different values between 1 and 5.5 Euros, and we provide various recommendations. A qualitative evaluation grid constantly places the SR technology as superior or equal to the 2 other techniques currently available. Our results demonstrated: a) the major interest of the non-intrusive AQC performed by RS, especially when it is not possible to analyze a TO with existing methods e.g. elastomeric portable pumps, and b) the high potential for this technique to be a strong contributor to the security of the medication circuit, and to fight the iatrogenic effects of drugs especially in the hospital. It also contributes to the protection of all actors in healthcare and of their working environment.

  20. Laser desorption single-conformation UV and IR spectroscopy of the sulfonamide drug sulfanilamide, the sulfanilamide-water complex, and the sulfanilamide dimer.

    Science.gov (United States)

    Uhlemann, Thomas; Seidel, Sebastian; Müller, Christian W

    2017-06-07

    We have studied the conformational preferences of the sulfonamide drug sulfanilamide, its dimer, and its monohydrated complex through laser desorption single-conformation UV and IR spectroscopy in a molecular beam. Based on potential energy curves for the inversion of the anilinic and the sulfonamide NH 2 groups calculated at DFT level, we suggest that the zero-point level wave function of the sulfanilamide monomer is appreciably delocalized over all four conformer wells. The sulfanilamide dimer, and the monohydrated complex each exhibit a single isomer in the molecular beam. The isomeric structures of the sulfanilamide dimer and the monohydrated sulfanilamide complex were assigned based on their conformer-specific IR spectra in the NH and OH stretch region. Quantum Theory of Atoms in Molecules (QTAIM) analysis of the calculated electron density in the water complex suggests that the water molecule is bound side-on in a hydrogen bonding pocket, donating one O-HO[double bond, length as m-dash]S hydrogen bond and accepting two hydrogen bonds, a NHO and a CHO hydrogen bond. QTAIM analysis of the dimer electron density suggests that the C i symmetry dimer structure exhibits two dominating N-HO[double bond, length as m-dash]S hydrogen bonds, and three weaker types of interactions: two CHO bonds, two CHN bonds, and a chalcogen OO interaction. Most interestingly, the molecular beam dimer structure closely resembles the R dimer unit - the dimer unit with the greatest interaction energy - of the α, γ, and δ crystal polymorphs. Interacting Quantum Atoms analysis provides evidence that the total intermolecular interaction in the dimer is dominated by the short-range exchange-correlation contribution.

  1. Sources, instrumentation and detectors for protein crystallography

    CERN Document Server

    Nave, C

    2001-01-01

    Some of the requirements for protein crystallography experiments on a synchrotron are described. Although data from different types of crystal are often collected without changing the X-ray beam properties, there are benefits if the incident beam is matched to a particular crystal and its diffraction pattern. These benefits are described with some examples. Radiation damage and other effects impose limits on the dose and dose rate on a protein crystal if the maximum amount of data is to be obtained. These limitations have possible consequences for the X-ray source required. Presently available commercial detector systems provide excellent data for protein crystallography but do not quite reach the specifications of the 'ideal' detector. In order to collect the most accurate data (e.g. for very weak anomalous scattering applications) detectors that produce near photon counting statistics over a wide dynamic range are required. It is possible that developments in 'pixel' detectors will allow these demanding exp...

  2. Serial Millisecond Crystallography of Membrane Proteins.

    Science.gov (United States)

    Jaeger, Kathrin; Dworkowski, Florian; Nogly, Przemyslaw; Milne, Christopher; Wang, Meitian; Standfuss, Joerg

    2016-01-01

    Serial femtosecond crystallography (SFX) at X-ray free-electron lasers (XFELs) is a powerful method to determine high-resolution structures of pharmaceutically relevant membrane proteins. Recently, the technology has been adapted to carry out serial millisecond crystallography (SMX) at synchrotron sources, where beamtime is more abundant. In an injector-based approach, crystals grown in lipidic cubic phase (LCP) or embedded in viscous medium are delivered directly into the unattenuated beam of a microfocus beamline. Pilot experiments show the application of microjet-based SMX for solving the structure of a membrane protein and compatibility of the method with de novo phasing. Planned synchrotron upgrades, faster detectors and software developments will go hand-in-hand with developments at free-electron lasers to provide a powerful methodology for solving structures from microcrystals at room temperature, ligand screening or crystal optimization for time-resolved studies with minimal or no radiation damage.

  3. The design of macromolecular crystallography diffraction experiments

    International Nuclear Information System (INIS)

    Evans, Gwyndaf; Axford, Danny; Owen, Robin L.

    2011-01-01

    Thoughts about the decisions made in designing macromolecular X-ray crystallography experiments at synchrotron beamlines are presented. The measurement of X-ray diffraction data from macromolecular crystals for the purpose of structure determination is the convergence of two processes: the preparation of diffraction-quality crystal samples on the one hand and the construction and optimization of an X-ray beamline and end station on the other. Like sample preparation, a macromolecular crystallography beamline is geared to obtaining the best possible diffraction measurements from crystals provided by the synchrotron user. This paper describes the thoughts behind an experiment that fully exploits both the sample and the beamline and how these map into everyday decisions that users can and should make when visiting a beamline with their most precious crystals

  4. On R factors for dynamic structure crystallography

    DEFF Research Database (Denmark)

    Coppens, Philip; Kaminski, Radoslaw; Schmøkel, Mette Stokkebro

    2010-01-01

    In studies of dynamic changes in crystals in which induced metastable species may have lifetimes of microseconds or less, refinements are most sensitive if based on the changes induced in the measured intensities. Agreement factors appropriate for such refinements, based on the ratios of the inte...... of the intensities before and after the external perturbation is applied, are discussed and compared with R factors commonly applied in static structure crystallography....

  5. Effect of Molecular Guest Binding on the d-d Transitions of Ni2+ of CPO-27-Ni: A Combined UV-Vis, Resonant-Valence-to-Core X-ray Emission Spectroscopy, and Theoretical Study.

    Science.gov (United States)

    Gallo, Erik; Gorelov, Evgeny; Guda, Alexander A; Bugaev, Aram L; Bonino, Francesca; Borfecchia, Elisa; Ricchiardi, Gabriele; Gianolio, Diego; Chavan, Sachin; Lamberti, Carlo

    2017-12-04

    We used Ni K-edge resonant-valence-to-core X-ray emission spectroscopy (RVtC-XES, also referred to as direct RIXS), an element-selective bulk-sensitive synchrotron-based technique, to investigate the electronic structure of the CPO-27-Ni metal-organic framework (MOF) upon molecular adsorption of significant molecular probes: H 2 O, CO, H 2 S, and NO. We compare RVtC-XES with UV-vis spectroscopy, and we show that the element selectivity of RVtC-XES is of strategic significance to observe the full set of d-d excitations in Ni 2+ , which are partially overshadowed by the low-energy π-π* transitions of the Ni ligands in standard diffuse-reflectance UV-vis experiments. Our combined RVtC-XES/UV-vis approach provides access to the whole set of d-d excitations, allowing us a complete discussion of the changes undergone by the electronic configuration of the Ni 2+ sites hosted within the MOF upon molecular adsorption. The experimental data have been interpreted by multiplet ligand-field theory calculations based on Wannier orbitals. This study represents a step further in understanding the ability of the CPO-27-Ni MOFs in molecular sorption and separation applications.

  6. Structural determination of individual chemical species in a mixed system by iterative transformation factor analysis-based X-ray absorption spectroscopy combined with UV-visible absorption and quantum chemical calculation.

    Science.gov (United States)

    Ikeda, Atsushi; Hennig, Christoph; Rossberg, André; Tsushima, Satoru; Scheinost, Andreas C; Bernhard, Gert

    2008-02-15

    A multitechnique approach using extended X-ray absorption fine structure (EXAFS) spectroscopy based on iterative transformation factor analysis (ITFA), UV-visible absorption spectroscopy, and density functional theory (DFT) calculations has been performed in order to investigate the speciation of uranium(VI) nitrate species in acetonitrile and to identify the complex structure of individual species in the system. UV-visible spectral titration suggests that there are four different species in the system, that is, pure solvated species, mono-, di-, and trinitrate species. The pure EXAFS spectra of these individual species are extracted by ITFA from the measured spectral mixtures on the basis of the speciation distribution profile calculated from the UV-visible data. Data analysis of the extracted EXAFS spectra, with the help of DFT calculations, reveals the most probable complex structures of the individual species. The pure solvated species corresponds to a uranyl hydrate complex with an equatorial coordination number (CNeq) of 5, [UO2(H2O)5]2+. Nitrate ions tend to coordinate to the uranyl(VI) ion in a bidentate fashion rather than a unidentate one in acetonitrile for all the nitrate species. The mononitrate species forms the complex of [UO2(H2O)3NO3]+ with a CNeq value of 5, while the di- and trinitrate species have a CNeq value of 6, corresponding to [UO2(H2O)2(NO3)2]0 (D2h) and [UO2(NO3)3]- (D3h), respectively.

  7. Facilities for small-molecule crystallography at synchrotron sources.

    Science.gov (United States)

    Barnett, Sarah A; Nowell, Harriott; Warren, Mark R; Wilcox, Andrian; Allan, David R

    2016-01-01

    Although macromolecular crystallography is a widely supported technique at synchrotron radiation facilities throughout the world, there are, in comparison, only very few beamlines dedicated to small-molecule crystallography. This limited provision is despite the increasing demand for beamtime from the chemical crystallography community and the ever greater overlap between systems that can be classed as either small macromolecules or large small molecules. In this article, a very brief overview of beamlines that support small-molecule single-crystal diffraction techniques will be given along with a more detailed description of beamline I19, a dedicated facility for small-molecule crystallography at Diamond Light Source.

  8. The basics of crystallography and diffraction

    CERN Document Server

    Hammond, C

    2015-01-01

    This title provides a clear and very broadly based introduction to crystallography, light, X-ray, and electron diffraction; a knowledge of which is essential to students in a wide range of scientific disciplines but which is otherwise generally covered in subject-specific and more mathematically detailed texts. The book is also designed to appeal to the more general reader since it shows, by historical and biographical references, how the subject has developed from the work and insights of successive generations of crystallographers and scientists.

  9. X-Ray Crystallography: One Century of Nobel Prizes

    Science.gov (United States)

    Galli, Simona

    2014-01-01

    In 2012, the United Nations General Assembly declared 2014 the International Year of Crystallography. Throughout the year 2014 and beyond, all the crystallographic associations and societies active all over the world are organizing events to attract the wider public toward crystallography and the numerous topics to which it is deeply interlinked.…

  10. In situ macromolecular crystallography using microbeams

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny; Owen, Robin L.; Aishima, Jun [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Foadi, James [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Imperial College, London SW7 2AZ (United Kingdom); Morgan, Ann W.; Robinson, James I. [University of Leeds, Leeds LS9 7FT (United Kingdom); Nettleship, Joanne E.; Owens, Raymond J. [Research Complex at Harwell, Rutherford Appleton Laboratory R92, Didcot, Oxfordshire OX11 0DE (United Kingdom); Moraes, Isabel [Imperial College, London SW7 2AZ (United Kingdom); Fry, Elizabeth E.; Grimes, Jonathan M.; Harlos, Karl; Kotecha, Abhay; Ren, Jingshan; Sutton, Geoff; Walter, Thomas S. [University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Stuart, David I. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Evans, Gwyndaf, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2012-04-17

    A sample environment for mounting crystallization trays has been developed on the microfocus beamline I24 at Diamond Light Source. The technical developments and several case studies are described. Despite significant progress in high-throughput methods in macromolecular crystallography, the production of diffraction-quality crystals remains a major bottleneck. By recording diffraction in situ from crystals in their crystallization plates at room temperature, a number of problems associated with crystal handling and cryoprotection can be side-stepped. Using a dedicated goniometer installed on the microfocus macromolecular crystallography beamline I24 at Diamond Light Source, crystals have been studied in situ with an intense and flexible microfocus beam, allowing weakly diffracting samples to be assessed without a manual crystal-handling step but with good signal to noise, despite the background scatter from the plate. A number of case studies are reported: the structure solution of bovine enterovirus 2, crystallization screening of membrane proteins and complexes, and structure solution from crystallization hits produced via a high-throughput pipeline. These demonstrate the potential for in situ data collection and structure solution with microbeams.

  11. In situ macromolecular crystallography using microbeams

    International Nuclear Information System (INIS)

    Axford, Danny; Owen, Robin L.; Aishima, Jun; Foadi, James; Morgan, Ann W.; Robinson, James I.; Nettleship, Joanne E.; Owens, Raymond J.; Moraes, Isabel; Fry, Elizabeth E.; Grimes, Jonathan M.; Harlos, Karl; Kotecha, Abhay; Ren, Jingshan; Sutton, Geoff; Walter, Thomas S.; Stuart, David I.; Evans, Gwyndaf

    2012-01-01

    A sample environment for mounting crystallization trays has been developed on the microfocus beamline I24 at Diamond Light Source. The technical developments and several case studies are described. Despite significant progress in high-throughput methods in macromolecular crystallography, the production of diffraction-quality crystals remains a major bottleneck. By recording diffraction in situ from crystals in their crystallization plates at room temperature, a number of problems associated with crystal handling and cryoprotection can be side-stepped. Using a dedicated goniometer installed on the microfocus macromolecular crystallography beamline I24 at Diamond Light Source, crystals have been studied in situ with an intense and flexible microfocus beam, allowing weakly diffracting samples to be assessed without a manual crystal-handling step but with good signal to noise, despite the background scatter from the plate. A number of case studies are reported: the structure solution of bovine enterovirus 2, crystallization screening of membrane proteins and complexes, and structure solution from crystallization hits produced via a high-throughput pipeline. These demonstrate the potential for in situ data collection and structure solution with microbeams

  12. Ultra-high resolution protein crystallography

    International Nuclear Information System (INIS)

    Takeda, Kazuki; Hirano, Yu; Miki, Kunio

    2010-01-01

    Many protein structures have been determined by X-ray crystallography and deposited with the Protein Data Bank. However, these structures at usual resolution (1.5< d<3.0 A) are insufficient in their precision and quantity for elucidating the molecular mechanism of protein functions directly from structural information. Several studies at ultra-high resolution (d<0.8 A) have been performed with synchrotron radiation in the last decade. The highest resolution of the protein crystals was achieved at 0.54 A resolution for a small protein, crambin. In such high resolution crystals, almost all of hydrogen atoms of proteins and some hydrogen atoms of bound water molecules are experimentally observed. In addition, outer-shell electrons of proteins can be analyzed by the multipole refinement procedure. However, the influence of X-rays should be precisely estimated in order to derive meaningful information from the crystallographic results. In this review, we summarize refinement procedures, current status and perspectives for ultra high resolution protein crystallography. (author)

  13. [Determination of Trace Lead in Water by UV-Visible Diffuse Reflectance Spectroscopy Combined with Surfactant and Membrane Filtration-Enrichment].

    Science.gov (United States)

    Zhang, Xiao-fang; Zhu, Bi-lin; Li, Wei; Wang, Lei; Zhang, Lei; Wu, Ting; Du, Yi-ping

    2015-07-01

    In this paper, a method of determination of trace lead in water by UV-Visible diffuse reflectance spectroscopy combined with surfactant and membrane filtration enrichment was proposed. In the NH3 x H2O-NH4Cl buffer solution with pH 8.5, the lead(II) ion would react with dithizone to form the red complex under vigorous stirring, which is hydrophobic and can be enriched by the mixed cellulose ester membrane. In addition, the nonionic surfactant Polyoxyethylene lauryl ether (Brij-30) was added into the solution to improve the enrichment efficiency, then visible diffuse reflectance spectra of the membrane were measured directly after the membrane were naturally dried. We also optimized the reaction conditions which may affect the complexation reaction process, such as type of surfactants, the concentration of the surfactant, the reaction acidity, the concentration of dithizone as well as the reaction time. The research results show that under the optimum conditions, a good linear correlation between absorbance at 485 nm and concentration of lead in the range of 5.0-100.0 microg x L(-1) was obtained with a squared correlation coefficient (R2) of 0.9906, and the detection limit was estimated accordingly to be 2.88 microg x L(-1). To determine real water sample, the interference from some potential coexisting ions was also studied at the optimal conditions when the concentration of lead (II) ion standard solution was fixed to 20 microg x L(-1). The results indicate that the following ions cannot interfere in the determination of lead with the proposed method: 500 times of the K+, Na+, Ca2+, Mg2+, NH4+, NO3-, Cl-, CH3COO-, SO4(2-); 10 times of the Al3+ (using 10% NaF as a masking reagent to avoid the interference); 10 times of the Fe3+ (using 10% NaF and 10% sodium potassium tartrate as masking reagents); 10 times of Hg2+ or Zn2+ (using 10% NaSCN and 10% potassium sodium tartrate as masking reagents); the same amount of Cd2+, Cu2+. The proposed method was applied to the

  14. Size-selective precipitation in colloidal semiconductor nanocrystals of CdTe and CdSe: a study by UV-VIS spectroscopy; Precipitacao seletiva de tamanhos em nanoparticulas semicondutoras coloidais de CdTe e CdSe: um estudo por espectroscopia UV-VIS

    Energy Technology Data Exchange (ETDEWEB)

    Viol, Livia Cristina de Souza; Silva, Fernanda Oliveira; Ferreira, Diego Lourenconi; Alves, Jose Luiz Aarestrup; Schiavon, Marco Antonio, E-mail: schiavon@ufsj.edu.b [Universidade Federal de Sao Joao del Rei, MG (Brazil). Dept. de Ciencias Naturais

    2011-07-01

    The post-preparative size-selective precipitation technique was applied in CdTe and CdSe semiconductor nanocrystals prepared via colloidal route in water. The synthesis of CdTe and CdSe nanoparticles and the effect of the post-preparative size-selective precipitation have been characterized mainly by mean of ultraviolet and visible absorption spectroscopy (UV-Vis). It was demonstrated that the size-selective precipitation are able to isolate particles of different sizes and purify the nanoparticles as well. (author)

  15. Probing photochromic properties by correlation of UV-visible and infra-red absorption spectroscopy: a case study with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene.

    Science.gov (United States)

    Spangenberg, Arnaud; Piedras Perez, Jose Alejandro; Patra, Abhijit; Piard, Jonathan; Brosseau, Arnaud; Métivier, Rémi; Nakatani, Keitaro

    2010-02-01

    Quantification of the relative composition of the isomers in a photochromic system at any irradiation time interval is a critical issue in determining absolute quantum yields. For this purpose, we have developed a simple and convenient protocol involving combination of UV-visible and infra-red absorption spectroscopy. Photochromic cyclization reaction of cis-l,2-dicyano-l,2-bis(2,4,5-trimethyl-3-thieny1)ethene (CMTE) is analyzed to demonstrate the efficiency of the proposed methodology. This approach is based on the fact that the two isomers show distinctive infra-red bands. Detailed investigations of the UV-visible and infra-red spectra of the mixture obtained at different irradiation times in CCl(4) supported by quantum chemical computations lead to the unambiguous estimation of molar absorption coefficients of the closed isomer (epsilon(CF) = 4650 L mol(-1) cm(-1) at 512 nm). It facilitates the first determination of absolute quantum yields of this reversible photochromic reaction in CCl(4) by fitting the UV-visible spectral data (Phi(OF-->CF) = 0.41 +/- 0.05 and Phi(CF-->OF) = 0.12 +/- 0.02 at 405 nm and 546 nm, respectively).

  16. Identification of Intermediates in Zeolite-Catalyzed Reactions Using In-situ UV/Vis Micro- Spectroscopy and a Complementary Set of Molecular Simulations

    NARCIS (Netherlands)

    Hemelsoet, K.L.J.; Qian, Q.|info:eu-repo/dai/nl/34138609X; De Meyer, T.; De Wispelaere, K.; De Sterck, B.; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397; Waroquier, M.; Van Speybroeck, V.

    2013-01-01

    The optical absorption properties of (poly)aromatic hydrocarbons occluded in a nanoporous environment were investigated by theoretical and experimental methods. The carbonaceous species are an essential part of a working catalyst for the methanol-toolefins (MTO) process. In situ UV/Vis microscopy

  17. UV-visible absorbance spectroscopy as a proxy for peatland dissolved organic carbon (DOC) quantity and quality: considerations on wavelength and absorbance degradation.

    Science.gov (United States)

    Peacock, Mike; Evans, Chris D; Fenner, Nathalie; Freeman, Chris; Gough, Rachel; Jones, Timothy G; Lebron, Inma

    2014-05-01

    Absorbance in the UV or visible spectrum (UV-vis) is commonly used as a proxy for DOC concentrations in waters draining upland catchments. To determine the appropriateness of different UV-vis measurements we used surface and pore water samples from two Welsh peatlands in four different experiments: (i) an assessment of single wavelength proxies (1 nm increments between 230-800 nm) for DOC concentration demonstrated that 254 nm was more accurate than 400 nm. The highest R(2) values between absorbance and DOC concentration were generated using 263 nm for one sample set (R(2) = 0.91), and 230 nm for the other three sample sets (respective R(2) values of 0.86, 0.81, and 0.93). (ii) A comparison of different DOC concentration proxies, including single wavelength proxies, a two wavelength model, a proxy using phenolic concentration, and a proxy using the area under a UV spectrum at 250-350 nm. It was found that both a single wavelength proxy (≤263 nm) and a two wavelength model performed well for both pore water and surface water. (iii) An evaluation of the E2 : E3, E2 : E4, E4 : E6 ratios, and SUVA (absorbance at 254 nm normalised to DOC concentration) as indicators of DOC quality showed that the E4 : E6 ratio was subject to extensive variation over time, and was highly correlated between surface water and pore water, suggesting that it is a useful metric to determine temporal changes in DOC quality. (iv) A repeated weekly analysis over twelve weeks showed no consistent change in UV-vis absorbance, and therefore an inferred lack of degradation of total DOC in samples that were filtered and stored in the dark at 4 °C.

  18. Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by nanosecond pulse of soft X-ray source and/or UV laser

    International Nuclear Information System (INIS)

    Bruza, Petr; Fidler, Vlastimil; Nikl, Martin

    2011-01-01

    The practical applicability of the rare-earth doped scintillators in high-speed detectors is limited by the slow decay components in the temporal response of a scintillator. The study of origin and properties of material defects that induce the slow decay components is of major importance for the development of new scintillation materials. We present a table-top, time-domain UV-VIS luminescence spectrometer, featuring extended time and input sensitivity ranges and two excitation sources. The combination of both soft X-ray/XUV and UV excitation source allows the comparative measurements of luminescence spectra and decay kinetics of scintillators to be performed under the same experimental conditions. The luminescence of emission centers of a doped scintillator can be induced by conventional N 2 laser pulse, while the complete scintillation process can be initiated by a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of 4 ns duration. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu 3 Al 5 O 12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of the doped Ce 3+ ions was studied under 2.88 nm (430 eV) XUV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3.68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d 2 transition of Ce 3+ is directly excited. Furthermore, YAG:Ce and LuAG:Ce single crystals luminescence decay profiles are compared and discussed.

  19. Structure determination by X-ray crystallography

    CERN Document Server

    Ladd, M F C

    1995-01-01

    X-ray crystallography provides us with the most accurate picture we can get of atomic and molecular structures in crystals. It provides a hard bedrock of structural results in chemistry and in mineralogy. In biology, where the structures are not fully crystalline, it can still provide valuable results and, indeed, the impact here has been revolutionary. It is still an immense field for young workers, and no doubt will provide yet more striking develop­ ments of a major character. It does, however, require a wide range of intellectual application, and a considerable ability in many fields. This book will provide much help. It is a very straightforward and thorough guide to every aspect of the subject. The authors are experienced both as research workers themselves and as teachers of standing, and this is shown in their clarity of exposition. There are plenty of iliustrations and worked examples to aid the student to obtain a real grasp of the subject.

  20. Electron crystallography with the EIGER detector

    Directory of Open Access Journals (Sweden)

    Gemma Tinti

    2018-03-01

    Full Text Available Electron crystallography is a discipline that currently attracts much attention as method for inorganic, organic and macromolecular structure solution. EIGER, a direct-detection hybrid pixel detector developed at the Paul Scherrer Institut, Switzerland, has been tested for electron diffraction in a transmission electron microscope. EIGER features a pixel pitch of 75 × 75 µm2, frame rates up to 23 kHz and a dead time between frames as low as 3 µs. Cluster size and modulation transfer functions of the detector at 100, 200 and 300 keV electron energies are reported and the data quality is demonstrated by structure determination of a SAPO-34 zeotype from electron diffraction data.

  1. Viscous hydrophilic injection matrices for serial crystallography

    Directory of Open Access Journals (Sweden)

    Gabriela Kovácsová

    2017-07-01

    Full Text Available Serial (femtosecond crystallography at synchrotron and X-ray free-electron laser (XFEL sources distributes the absorbed radiation dose over all crystals used for data collection and therefore allows measurement of radiation damage prone systems, including the use of microcrystals for room-temperature measurements. Serial crystallography relies on fast and efficient exchange of crystals upon X-ray exposure, which can be achieved using a variety of methods, including various injection techniques. The latter vary significantly in their flow rates – gas dynamic virtual nozzle based injectors provide very thin fast-flowing jets, whereas high-viscosity extrusion injectors produce much thicker streams with flow rates two to three orders of magnitude lower. High-viscosity extrusion results in much lower sample consumption, as its sample delivery speed is commensurate both with typical XFEL repetition rates and with data acquisition rates at synchrotron sources. An obvious viscous injection medium is lipidic cubic phase (LCP as it is used for in meso membrane protein crystallization. However, LCP has limited compatibility with many crystallization conditions. While a few other viscous media have been described in the literature, there is an ongoing need to identify additional injection media for crystal embedding. Critical attributes are reliable injection properties and a broad chemical compatibility to accommodate samples as heterogeneous and sensitive as protein crystals. Here, the use of two novel hydrogels as viscous injection matrices is described, namely sodium carboxymethyl cellulose and the thermo-reversible block polymer Pluronic F-127. Both are compatible with various crystallization conditions and yield acceptable X-ray background. The stability and velocity of the extruded stream were also analysed and the dependence of the stream velocity on the flow rate was measured. In contrast with previously characterized injection media, both new

  2. Development of the protein crystallography by synchrotron radiation

    International Nuclear Information System (INIS)

    Yamamoto, Masaki

    2014-01-01

    Since crystal structure determination of the first protein by Kendrew in 1959, protein crystallography developed into the leading role of the protein structure study by various technology developments. Especially the utilization of synchrotron radiation from the 1990s brought innovative progress of protein crystallography on the data quality and the phasing method and had expanded the samples targets including membrane proteins and suprarmolecular complexes. Here I give the outline of the history and the future prospects of the protein crystallography from the role of synchrotron radiation. (author)

  3. Sub-atomic resolution X-ray crystallography and neutron crystallography: promise, challenges and potential.

    Science.gov (United States)

    Blakeley, Matthew P; Hasnain, Samar S; Antonyuk, Svetlana V

    2015-07-01

    The International Year of Crystallography saw the number of macromolecular structures deposited in the Protein Data Bank cross the 100000 mark, with more than 90000 of these provided by X-ray crystallography. The number of X-ray structures determined to sub-atomic resolution (i.e. ≤1 Å) has passed 600 and this is likely to continue to grow rapidly with diffraction-limited synchrotron radiation sources such as MAX-IV (Sweden) and Sirius (Brazil) under construction. A dozen X-ray structures have been deposited to ultra-high resolution (i.e. ≤0.7 Å), for which precise electron density can be exploited to obtain charge density and provide information on the bonding character of catalytic or electron transfer sites. Although the development of neutron macromolecular crystallography over the years has been far less pronounced, and its application much less widespread, the availability of new and improved instrumentation, combined with dedicated deuteration facilities, are beginning to transform the field. Of the 83 macromolecular structures deposited with neutron diffraction data, more than half (49/83, 59%) were released since 2010. Sub-mm(3) crystals are now regularly being used for data collection, structures have been determined to atomic resolution for a few small proteins, and much larger unit-cell systems (cell edges >100 Å) are being successfully studied. While some details relating to H-atom positions are tractable with X-ray crystallography at sub-atomic resolution, the mobility of certain H atoms precludes them from being located. In addition, highly polarized H atoms and protons (H(+)) remain invisible with X-rays. Moreover, the majority of X-ray structures are determined from cryo-cooled crystals at 100 K, and, although radiation damage can be strongly controlled, especially since the advent of shutterless fast detectors, and by using limited doses and crystal translation at micro-focus beams, radiation damage can still take place. Neutron

  4. Sub-atomic resolution X-ray crystallography and neutron crystallography: promise, challenges and potential

    Directory of Open Access Journals (Sweden)

    Matthew P. Blakeley

    2015-07-01

    Full Text Available The International Year of Crystallography saw the number of macromolecular structures deposited in the Protein Data Bank cross the 100000 mark, with more than 90000 of these provided by X-ray crystallography. The number of X-ray structures determined to sub-atomic resolution (i.e. ≤1 Å has passed 600 and this is likely to continue to grow rapidly with diffraction-limited synchrotron radiation sources such as MAX-IV (Sweden and Sirius (Brazil under construction. A dozen X-ray structures have been deposited to ultra-high resolution (i.e. ≤0.7 Å, for which precise electron density can be exploited to obtain charge density and provide information on the bonding character of catalytic or electron transfer sites. Although the development of neutron macromolecular crystallography over the years has been far less pronounced, and its application much less widespread, the availability of new and improved instrumentation, combined with dedicated deuteration facilities, are beginning to transform the field. Of the 83 macromolecular structures deposited with neutron diffraction data, more than half (49/83, 59% were released since 2010. Sub-mm3 crystals are now regularly being used for data collection, structures have been determined to atomic resolution for a few small proteins, and much larger unit-cell systems (cell edges >100 Å are being successfully studied. While some details relating to H-atom positions are tractable with X-ray crystallography at sub-atomic resolution, the mobility of certain H atoms precludes them from being located. In addition, highly polarized H atoms and protons (H+ remain invisible with X-rays. Moreover, the majority of X-ray structures are determined from cryo-cooled crystals at 100 K, and, although radiation damage can be strongly controlled, especially since the advent of shutterless fast detectors, and by using limited doses and crystal translation at micro-focus beams, radiation damage can still take place

  5. H-aggregate analysis of P3HT thin films-Capability and limitation of photoluminescence and UV/Vis spectroscopy.

    Science.gov (United States)

    Ehrenreich, Philipp; Birkhold, Susanne T; Zimmermann, Eugen; Hu, Hao; Kim, Kwang-Dae; Weickert, Jonas; Pfadler, Thomas; Schmidt-Mende, Lukas

    2016-09-01

    Polymer morphology and aggregation play an essential role for efficient charge carrier transport and charge separation in polymer-based electronic devices. It is a common method to apply the H-aggregate model to UV/Vis or photoluminescence spectra in order to analyze polymer aggregation. In this work we present strategies to obtain reliable and conclusive information on polymer aggregation and morphology based on the application of an H-aggregate analysis on UV/Vis and photoluminescence spectra. We demonstrate, with P3HT as model system, that thickness dependent reflection behavior can lead to misinterpretation of UV/Vis spectra within the H-aggregate model. Values for the exciton bandwidth can deviate by a factor of two for polymer thicknesses below 150 nm. In contrast, photoluminescence spectra are found to be a reliable basis for characterization of polymer aggregation due to their weaker dependence on the wavelength dependent refractive index of the polymer. We demonstrate this by studying the influence of surface characteristics on polymer aggregation for spin-coated thin-films that are commonly used in organic and hybrid solar cells.

  6. MX1: a bending-magnet crystallography beamline serving both chemical and macromolecular crystallography communities at the Australian Synchrotron

    International Nuclear Information System (INIS)

    Cowieson, Nathan Philip; Aragao, David; Clift, Mark; Ericsson, Daniel J.; Gee, Christine; Harrop, Stephen J.; Mudie, Nathan; Panjikar, Santosh; Price, Jason R.; Riboldi-Tunnicliffe, Alan; Williamson, Rachel; Caradoc-Davies, Tom

    2015-01-01

    The macromolecular crystallography beamline MX1 at the Australian Synchrotron is described. MX1 is a bending-magnet crystallography beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X-rays in the energy range from 8 to 18 keV to a focal spot at the sample position of 120 µm FWHM. The beamline endstation and ancillary equipment facilitate local and remote access for both chemical and biological macromolecular crystallography. Here, the design of the beamline and endstation are discussed. The beamline has enjoyed a full user program for the last seven years and scientific highlights from the user program are also presented

  7. Why do We Trust X-ray Crystallography?

    Indian Academy of Sciences (India)

    IAS Admin

    crystal X-ray diffraction pattern and good chemical sense that elevates X-ray crystallography to its position as the most trusted analytical technique. Suggested Reading. [1] William Clegg, Crystal Structure Determination, Oxford Chemistry Prim-.

  8. Chemical Crystallography· From Inception to Maturity

    Indian Academy of Sciences (India)

    design, charge density ... did not readily accept this first chemical crystallography experi- .... graphics. The packages clearly illustrate the complexity involved in both molecu- ... interactive online programs help to search, match and analyze.

  9. Fragment-based screening by protein crystallography: successes and pitfalls.

    Science.gov (United States)

    Chilingaryan, Zorik; Yin, Zhou; Oakley, Aaron J

    2012-10-08

    Fragment-based drug discovery (FBDD) concerns the screening of low-molecular weight compounds against macromolecular targets of clinical relevance. These compounds act as starting points for the development of drugs. FBDD has evolved and grown in popularity over the past 15 years. In this paper, the rationale and technology behind the use of X-ray crystallography in fragment based screening (FBS) will be described, including fragment library design and use of synchrotron radiation and robotics for high-throughput X-ray data collection. Some recent uses of crystallography in FBS will be described in detail, including interrogation of the drug targets β-secretase, phenylethanolamine N-methyltransferase, phosphodiesterase 4A and Hsp90. These examples provide illustrations of projects where crystallography is straightforward or difficult, and where other screening methods can help overcome the limitations of crystallography necessitated by diffraction quality.

  10. Fragment-Based Screening by Protein Crystallography: Successes and Pitfalls

    Directory of Open Access Journals (Sweden)

    Aaron J. Oakley

    2012-10-01

    Full Text Available Fragment-based drug discovery (FBDD concerns the screening of low-molecular weight compounds against macromolecular targets of clinical relevance. These compounds act as starting points for the development of drugs. FBDD has evolved and grown in popularity over the past 15 years. In this paper, the rationale and technology behind the use of X-ray crystallography in fragment based screening (FBS will be described, including fragment library design and use of synchrotron radiation and robotics for high-throughput X-ray data collection. Some recent uses of crystallography in FBS will be described in detail, including interrogation of the drug targets β-secretase, phenylethanolamine N-methyltransferase, phosphodiesterase 4A and Hsp90. These examples provide illustrations of projects where crystallography is straightforward or difficult, and where other screening methods can help overcome the limitations of crystallography necessitated by diffraction quality.

  11. Crystallography and Interphase Boundary of Martensite and Bainite in Steels

    Science.gov (United States)

    Furuhara, Tadashi; Chiba, Tadachika; Kaneshita, Takeshi; Wu, Huidong; Miyamoto, Goro

    2017-06-01

    Grain refinements in lath martensite and bainite structures are crucial for strengthening and toughening of high-strength structural steels. Clearly, crystallography of transformation plays an important role in determining the "grain" sizes in these structures. In the present study, crystallography and intrinsic boundary structure of martensite and bainite are described. Furthermore, various extrinsic factors affecting variant selection and growth kinetics, such as elastic/plastic strain and alloying effects on interphase boundary migration, are discussed.

  12. Celebrating macromolecular crystallography: A personal perspective

    Directory of Open Access Journals (Sweden)

    Abad-Zapatero, Celerino

    2015-04-01

    Full Text Available The twentieth century has seen an enormous advance in the knowledge of the atomic structures that surround us. The discovery of the first crystal structures of simple inorganic salts by the Braggs in 1914, using the diffraction of X-rays by crystals, provided the critical elements to unveil the atomic structure of matter. Subsequent developments in the field leading to macromolecular crystallography are presented with a personal perspective, related to the cultural milieu of Spain in the late 1950’s. The journey of discovery of the author, as he developed professionally, is interwoven with the expansion of macromolecular crystallography from the first proteins (myoglobin, hemoglobin to the ‘coming of age’ of the field in 1971 and the discoveries that followed, culminating in the determination of the structure of the ribosomes at the turn of the century. A perspective is presented exploring the future of the field and also a reflection about the future generations of Spanish scientists.El siglo XX ha sido testigo del increíble avance que ha experimentado el conocimiento de la estructura atómica de la materia que nos rodea. El descubrimiento de las primeras estructuras atómicas de sales inorgánicas por los Bragg en 1914, empleando difracción de rayos X con cristales, proporcionó los elementos clave para alcanzar tal conocimiento. Posteriores desarrollos en este campo, que condujeron a la cristalografía macromolecular, se presentan aquí desde una perspectiva personal, relacionada con el contexto cultural de la España de la década de los 50. La experiencia del descubrimiento científico, durante mi desarrollo profesional, se integra en el desarrollo de la cristalografía macromolecular, desde las primeras proteínas (míoglobina y hemoglobina, hasta su madurez en 1971 que, con los posteriores descubrimientos, culmina con la determinación del la estructura del ribosoma. Asimismo, se explora el futuro de esta disciplina y se

  13. Charging of Self-Doped Poly(Anilineboronic Acid) Films Studied by in Situ ESR/UV/Vis/NIR Spectroelectrochemistry and ex Situ FTIR Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Moraes, I. R.; Kalbáč, Martin; Dmitrieva, E.; Dunsch, L.

    2011-01-01

    Roč. 12, č. 16 (2011), s. 2920-2924 ISSN 1439-4235 R&D Projects: GA ČR GC203/07/J067 Institutional research plan: CEZ:AV0Z40400503 Keywords : conducting polymers * films * FTIR spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 3.412, year: 2011

  14. Green biochemistry approach for synthesis of silver and gold nanoparticles using Ficus racemosa latex and their pH-dependent binding study with different amino acids using UV/Vis absorption spectroscopy.

    Science.gov (United States)

    Tetgure, Sandesh R; Borse, Amulrao U; Sankapal, Babasaheb R; Garole, Vaman J; Garole, Dipak J

    2015-04-01

    Simple and eco-friendly biosynthesis approach was developed to synthesize silver nanoparticles (SNPs) and gold nanoparticles (GNPs) using Ficus racemosa latex as reducing agent. The presence of sunlight is utilized with latex and achieved the nanoparticles whose average size was in the range of 50-120 nm for SNPs and 20-50 nm for GNPs. The synthesized nanoparticles were characterized by UV/Visible absorption spectroscopy, X-ray diffraction, and field emission-scanning electron microscopy techniques toget understand the obtained nanoparticles. The pH-dependent binding studies of SNPs and GNPs with four amino acids, namely L-lysine, L-arginine, L-glutamine and glycin have been reported.

  15. Use of diffusion-ordered NMR spectroscopy and HPLC-UV-SPE-NMR to identify undeclared synthetic drugs in medicines illegally sold as phytotherapies.

    Science.gov (United States)

    Silva, Lorena M A; Filho, Elenilson G A; Thomasi, Sérgio S; Silva, Bianca F; Ferreira, Antonio G; Venâncio, Tiago

    2013-09-01

    The informal (and/or illegal) e-commerce of pharmaceutical formulations causes problems that governmental health agencies find hard to control, one of which concerns formulas sold as natural products. The purpose of this work was to explore the advantages and limitations of DOSY and HPLC-UV-SPE-NMR. These techniques were used to identify the components of a formula illegally marketed in Brazil as an herbal medicine possessing anti-inflammatory and analgesic properties. DOSY was able to detect the major components present at higher concentrations. Complete characterization was achieved using HPLC-UV-SPE-NMR, and 1D and 2D NMR analyses enabled the identification of known synthetic drugs. These were ranitidine and a mixture of orphenadrine citrate, piroxicam, and dexamethasone, which are co-formulated in a remedy called Rheumazim that is used to relieve severe pain, but it is prohibited in Brazil because of a lack of sufficient pharmacokinetic and pharmacodynamic information. Copyright © 2013 John Wiley & Sons, Ltd.

  16. The pentane- and toluene-soluble fractions of a petroleum residue and three coal tars by size exclusion chromatography and UV-fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Karaca, F.; Millan-Agorio, M.; Morgan, T.J.; Bull, I.D.; Herod, A.A.; Kandiyoti, R. [University of London Imperial College Science Technology & Medicine, London (United Kingdom). Dept. of Chemical Engineering

    2008-01-15

    A petroleum atmospheric pressure distillate residue and three tars derived from different coals using different severities of thermal treatment were separated into seven fractions using column chromatography on silica and sequential elution by the solvent sequence pentane, toluene, acetonitrile, pyridine, 1-methyl-2-pyrrolidinone (NMP) and water. The fractions from the four extractions have been compared using size exclusion chromatography (SEC) in NMP as eluent and by synchronous ultra-violet-fluorescence (UV-F). This paper concerns the pentane and toluene soluble fractions only since these are the least polar fractions. By SEC, the size of the aromatic molecules increased from the first pentane soluble fractions to the toluene-soluble fractions, with the petroleum residue fractions of larger size than the equivalent fractions from coal liquids. The three coal tars showed significant differences, indicating that temperature of pyrolysis had a significant effect on the molecular size. Synchronous UV-F spectra of the four sets of fractions, in solution in NMP, again showed significant differences between the petroleum residue and the coal tars, as well as amongst the three coal tars. In general, the petroleum residue fractions contained smaller aromatic clusters than the coal liquid fractions. These low-polarity fractions contained material excluded from the column porosity in SEC that was unlikely to consist of aggregates of polar molecules.

  17. Predicting Keto-Enol Equilibrium from Combining UV/Visible Absorption Spectroscopy with Quantum Chemical Calculations of Vibronic Structures for Many Excited States. A Case Study on Salicylideneanilines.

    Science.gov (United States)

    Zutterman, Freddy; Louant, Orian; Mercier, Gabriel; Leyssens, Tom; Champagne, Benoît

    2018-06-21

    Salicylideneanilines are characterized by a tautomer equilibrium, between an enol and a keto form of different colors, at the origin of their remarkable thermochromic, solvatochromic, and photochromic properties. The enol form is usually the most stable but appropriate choice of substituents and conditions (solvent, crystal, host compound) can displace the equilibrium toward the keto form so that there is a need for fast prediction of the keto:enol abundance ratio. Here we demonstrate the reliability of a combined theoretical-experimental method, based on comparing simulated and measured UV/visible absorption spectra, to determine this keto/enol ratio. The calculations of the excitation energies, oscillator strengths, and vibronic structures of both enol and keto forms are performed for all excited states absorbing in the relevant (visible and near-UV) wavelength range at the time-dependent density functional theory level by accounting for solvent effects using the polarizable continuum model. This approach is illustrated for two salicylideneaniline derivatives, which are present, in solution, under the form of keto-enol mixtures. The results are compared to those of chemometric analysis as well as ab initio predictions of the reaction free enthalpies.

  18. Structural Identification of 19 Purified Isomers of the OPV Acceptor Material bisPCBM by 13C NMR and UV-Vis Absorption Spectroscopy and High-Performance Liquid Chromatography.

    Science.gov (United States)

    Liu, Tong; Abrahams, Isaac; Dennis, T John S

    2018-04-26

    The molecular structures of 19 purified isomers of bis-phenyl-C 62 -butyric acid methyl ester were identified by a combination of 13 C NMR and UV-vis absorption spectroscopies and high-performance liquid chromatography (HPLC) retention time analysis. All 19 isomers are dicyclopropafullerenes (none are homofullerenes). There were seven isomers with C 1 molecular point-group symmetry, four with C s , six with C 2 , one with C 2 v , and one with C 2 h symmetry. The C 2 h , C 2 v , and all five nonequatorial C 1 isomers were unambiguously assigned to their respective HPLC fractions. For the other 12 isomers, the 13 C NMR and UV-vis spectra placed them in six groups of two same-symmetry isomers. On the basis of the widely spaced HPLC retention times of the two isomers within each of these six groups, and the empirical inverse correlation between retention time and addend spacing, each isomer was assigned to its corresponding HPLC fraction. In addition, the missing trans-1 isomer was found, purified, and characterized.

  19. Electronic structure and spectroscopic properties of mononuclear manganese(III) Schiff base complexes: a systematic study on [Mn(acen)X] complexes by EPR, UV/vis, and MCD spectroscopy (X = Hal, NCS).

    Science.gov (United States)

    Westphal, Anne; Klinkebiel, Arne; Berends, Hans-Martin; Broda, Henning; Kurz, Philipp; Tuczek, Felix

    2013-03-04

    The manganese(III) Schiff base complexes [Mn(acen)X] (H2acen: N,N'-ethylenebis(acetylacetone)imine, X: I(-), Br(-), Cl(-), NCS(-)) are considered as model systems for a combined study of the electronic structure using vibrational, UV/vis absorption, parallel-mode electron paramagnetic resonance (EPR) and low-temperature magnetic circular dichroism (MCD) spectroscopy. By variation of the co-ligand X, the influence of the axial ligand field within a given square-pyramidal coordination geometry on the UV/vis, EPR, and MCD spectra of the title compounds is investigated. Between 25000 and 35000 cm(-1), the low-temperature MCD spectra are dominated by two very intense, oppositely signed pseudo-A terms, referred to as "double pseudo-A terms", which change their signs within the [Mn(acen)X] series dependent on the axial ligand X. Based on molecular orbital (MO) and symmetry considerations, these features are assigned to π(n.b.)(s, a) → yz, z(2) ligand-to-metal charge transfer transitions. The individual MCD signs are directly determined from the calculated MOs of the [Mn(acen)X] complexes. The observed sign change is explained by an inversion of symmetry among the π(n.b.)(s, a) donor orbitals which leads to an interchange of the positive and negative pseudo-A terms constituting the "double pseudo-A term".

  20. Discoloration of fired kaolinitic clays (Study of Fe+3 coordination by Mössbauer and UV-ViS-NIR spectroscopy)

    Czech Academy of Sciences Publication Activity Database

    Hanzlíček, Tomáš; Nižňanský, D.; Dědeček, Jiří; Steinerová, Michaela; Straka, Pavel; Třísková, J.

    2007-01-01

    Roč. 90, č. 9 (2007), s. 2843-2848 ISSN 0002-7820 R&D Projects: GA AV ČR IAA300460702 Institutional research plan: CEZ:AV0Z30460519; CEZ:AV0Z40400503 Keywords : kaolin * clay * Mössbauer spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 1.792, year: 2007 www.blackwell- synergy .com

  1. Assessment of organic pollution of an industrial river by synchronous fluorescence and UV-vis spectroscopy: the Fensch River (NE France).

    Science.gov (United States)

    Assaad, Aziz; Pontvianne, Steve; Pons, Marie-Noëlle

    2017-05-01

    To rapidly monitor the surface water quality in terms of organic pollution of an industrial river undergoing restoration, optical methods (UV-visible spectrometry and fluorescence) were applied in parallel to classical physical-chemical analyses. UV-visible spectra were analyzed using the maximum of the second derivative at 225 nm (related to nitrates), specific absorbance at 254 nm (SUVA 254 ), and the spectral slope between 275 and 295 nm (S 275-295 ) (related to the aromaticity and molecular weight of dissolved organic carbon). The synchronous fluorescence spectra (wavelength difference = 50 nm) exhibited a high variability in the composition of dissolved organic material between the upstream and downstream sections and also versus time. The principal components analysis of the entire set of synchronous fluorescence spectra helped to define three river sections with different pollution characteristics. Spectral decomposition was applied to the two most upstream sections: five fluorophores, classical in rivers impacted by domestic sewage and related to protein-like (λ ex  = 280 nm) and humic-like fluorescence (M-type with λ ex  ≈ 305-310 nm and C-type with λ ex  ≥ 335 nm), were identified. The irregular shape of the synchronous fluorescence spectra in the most downstream section is likely due to organic pollutants of industrial origin; however, their variability and the complexity of the spectra did not allow the further elucidation of their nature.

  2. Submersible UV-Vis spectroscopy for quantifying streamwater organic carbon dynamics: implementation and challenges before and after forest harvest in a headwater stream.

    Science.gov (United States)

    Jollymore, Ashlee; Johnson, Mark S; Hawthorne, Iain

    2012-01-01

    Organic material, including total and dissolved organic carbon (DOC), is ubiquitous within aquatic ecosystems, playing a variety of important and diverse biogeochemical and ecological roles. Determining how land-use changes affect DOC concentrations and bioavailability within aquatic ecosystems is an important means of evaluating the effects on ecological productivity and biogeochemical cycling. This paper presents a methodology case study looking at the deployment of a submersible UV-Vis absorbance spectrophotometer (UV-Vis spectro::lyzer model, s::can, Vienna, Austria) to determine stream organic carbon dynamics within a headwater catchment located near Campbell River (British Columbia, Canada). Field-based absorbance measurements of DOC were made before and after forest harvest, highlighting the advantages of high temporal resolution compared to traditional grab sampling and laboratory measurements. Details of remote deployment are described. High-frequency DOC data is explored by resampling the 30 min time series with a range of resampling time intervals (from daily to weekly time steps). DOC export was calculated for three months from the post-harvest data and resampled time series, showing that sampling frequency has a profound effect on total DOC export. DOC exports derived from weekly measurements were found to underestimate export by as much as 30% compared to DOC export calculated from high-frequency data. Additionally, the importance of the ability to remotely monitor the system through a recently deployed wireless connection is emphasized by examining causes of prior data losses, and how such losses may be prevented through the ability to react when environmental or power disturbances cause system interruption and data loss.

  3. Submersible UV-Vis Spectroscopy for Quantifying Streamwater Organic Carbon Dynamics: Implementation and Challenges before and after Forest Harvest in a Headwater Stream

    Directory of Open Access Journals (Sweden)

    Iain Hawthorne

    2012-03-01

    Full Text Available Organic material, including total and dissolved organic carbon (DOC, is ubiquitous within aquatic ecosystems, playing a variety of important and diverse biogeochemical and ecological roles. Determining how land-use changes affect DOC concentrations and bioavailability within aquatic ecosystems is an important means of evaluating the effects on ecological productivity and biogeochemical cycling. This paper presents a methodology case study looking at the deployment of a submersible UV-Vis absorbance spectrophotometer (UV-Vis spectro::lyzer model, s::can, Vienna, Austria to determine stream organic carbon dynamics within a headwater catchment located near Campbell River (British Columbia, Canada. Field-based absorbance measurements of DOC were made before and after forest harvest, highlighting the advantages of high temporal resolution compared to traditional grab sampling and laboratory measurements. Details of remote deployment are described. High-frequency DOC data is explored by resampling the 30 min time series with a range of resampling time intervals (from daily to weekly time steps. DOC export was calculated for three months from the post-harvest data and resampled time series, showing that sampling frequency has a profound effect on total DOC export. DOC exports derived from weekly measurements were found to underestimate export by as much as 30% compared to DOC export calculated from high-frequency data. Additionally, the importance of the ability to remotely monitor the system through a recently deployed wireless connection is emphasized by examining causes of prior data losses, and how such losses may be prevented through the ability to react when environmental or power disturbances cause system interruption and data loss.

  4. Langmuir-Blodgett nanotemplates for protein crystallography.

    Science.gov (United States)

    Pechkova, Eugenia; Nicolini, Claudio

    2017-12-01

    The new generation of synchrotrons and microfocused beamlines has enabled great progress in X-ray protein crystallography, resulting in new 3D atomic structures for proteins of high interest to the pharmaceutical industry and life sciences. It is, however, often still challenging to produce protein crystals of sufficient size and quality (order, intensity of diffraction, radiation stability). In this protocol, we provide instructions for performing the Langmuir-Blodgett (LB) nanotemplate method, a crystallization approach that can be used for any protein (including membrane proteins). We describe how to produce highly ordered 2D LB protein monolayers at the air-water interface and deposit them on glass slides. LB-film formation can be observed by surface-pressure measurements and Brewster angle microscopy (BAM), although its quality can be characterized by atomic force microscopy (AFM) and nanogravimetry. Such films are then used as a 2D template for triggering 3D protein crystal formation by hanging-drop vapor diffusion. The procedure for forming the 2D template takes a few minutes. Structural information about the protein reorganization in the LB film during the crystallization process on the nano level can be obtained using an in situ submicron GISAXS (grazing-incidence small-angle X-ray scattering) method. MicroGISAXS spectra, measured directly at the interface of the LB films and protein solution in real time, as described in this protocol, can be interpreted in terms of the buildup of layers, islands, or holes. In our experience, the obtained LB crystals take 1-10 d to prepare and they are more ordered and radiation stable as compared with those produced using other crystallization methods.

  5. Effect of UV laser irradiation on tissue

    International Nuclear Information System (INIS)

    Nakayama, Takeyoshi; Kubo, Uichi

    1992-01-01

    Laser-tissue interactions have been investigated through Electron Probe Micro Analysis (EPMA), UV-visible optical absorption and Fourier Transform Infrared Spectroscopy (FTIR). Three excimer lasers, ArF, KrF and XeCl, were used to irradiate tissue; cow thighbone and gelatin thin film. Features of UV laser irradiation are described. (author)

  6. Kinetics of the F+NO2+M->FNO2+M reaction studied by pulse radiolysis combined with time-resolved IR and UV spectroscopy

    DEFF Research Database (Denmark)

    Pagsberg, Palle Bjørn; Sillesen, A.; Jodkowski, J.T.

    1996-01-01

    was studied with SF6 pressures of 5-1000 mbar at 298 K. Comparative studies were carried out by monitoring the decay kinetics of NO2 at 445 nm using pressures of 100-1000 mbar at 295 and 341 K. The observed pressure dependence is represented in terms of a fall-off curve with the following values......The title reaction was initiated by the pulse radiolysis of SF6/NO2 gas mixtures, and the formation of FNO2 was studied by time-resolved infrared spectroscopy employing strong rotational transitions within the nu(1) and nu(4) bands of FNO2. The pressure dependence of the formation kinetics...

  7. Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Carr, J. K.; Roy, S.; Skinner, J. L. [Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, Wisconsin 53706 (United States); Zabuga, A. V.; Rizzo, T. R. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne (Switzerland)

    2014-06-14

    The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed “maps,” which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental and theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala){sub 5}-Lys-H{sup +} in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly {sup 13}C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and {sup 13}C{sup 18}O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm{sup −1} for both frequencies and couplings, having larger errors only for the frequencies of terminal amides.

  8. Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

    International Nuclear Information System (INIS)

    Carr, J. K.; Roy, S.; Skinner, J. L.; Zabuga, A. V.; Rizzo, T. R.

    2014-01-01

    The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed “maps,” which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental and theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala) 5 -Lys-H + in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly 13 C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and 13 C 18 O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm −1 for both frequencies and couplings, having larger errors only for the frequencies of terminal amides

  9. Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

    Science.gov (United States)

    Carr, J. K.; Zabuga, A. V.; Roy, S.; Rizzo, T. R.; Skinner, J. L.

    2014-01-01

    The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed “maps,” which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental and theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala)5-Lys-H+ in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly 13C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and 13C18O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm−1 for both frequencies and couplings, having larger errors only for the frequencies of terminal amides. PMID:24929378

  10. Measurements of the Weak UV Absorptions of Isoprene and Acetone at 261–275 nm Using Cavity Ringdown Spectroscopy for Evaluation of a Potential Portable Ringdown Breath Analyzer

    Science.gov (United States)

    Sahay, Peeyush; Scherrer, Susan T.; Wang, Chuji

    2013-01-01

    The weak absorption spectra of isoprene and acetone have been measured in the wavelength range of 261–275 nm using cavity ringdown spectroscopy. The measured absorption cross-sections of isoprene in the wavelength region of 261–266 nm range from 3.65 × 10−21 cm2·molecule−1 at 261 nm to 1.42 × 10−21 cm2·molecule−1 at 266 nm; these numbers are in good agreement with the values reported in the literature. In the longer wavelength range of 270–275 nm, however, where attractive applications using a single wavelength compact diode laser operating at 274 nm is located, isoprene has been reported in the literature to have no absorption (too weak to be detected). Small absorption cross-sections of isoprene in this longer wavelength region are measured using cavity ringdown spectroscopy for the first time in this work, i.e., 6.20 × 10−23 cm2·molecule−1 at 275 nm. With the same experimental system, wavelength-dependent absorption cross-sections of acetone have also been measured. Theoretical detection limits of isoprene and comparisons of absorbance of isoprene, acetone, and healthy breath gas in this wavelength region are also discussed. PMID:23803787

  11. UV-Photochemistry of the Disulfide Bond: Evolution of Early Photoproducts from Picosecond X-ray Absorption Spectroscopy at the Sulfur K-Edge.

    Science.gov (United States)

    Ochmann, Miguel; Hussain, Abid; von Ahnen, Inga; Cordones, Amy A; Hong, Kiryong; Lee, Jae Hyuk; Ma, Rory; Adamczyk, Katrin; Kim, Tae Kyu; Schoenlein, Robert W; Vendrell, Oriol; Huse, Nils

    2018-05-30

    We have investigated dimethyl disulfide as the basic moiety for understanding the photochemistry of disulfide bonds, which are central to a broad range of biochemical processes. Picosecond time-resolved X-ray absorption spectroscopy at the sulfur K-edge provides unique element-specific insight into the photochemistry of the disulfide bond initiated by 267 nm femtosecond pulses. We observe a broad but distinct transient induced absorption spectrum which recovers on at least two time scales in the nanosecond range. We employed RASSCF electronic structure calculations to simulate the sulfur-1s transitions of multiple possible chemical species, and identified the methylthiyl and methylperthiyl radicals as the primary reaction products. In addition, we identify disulfur and the CH 2 S thione as the secondary reaction products of the perthiyl radical that are most likely to explain the observed spectral and kinetic signatures of our experiment. Our study underscores the importance of elemental specificity and the potential of time-resolved X-ray spectroscopy to identify short-lived reaction products in complex reaction schemes that underlie the rich photochemistry of disulfide systems.

  12. New design of experiment combined with UV-Vis spectroscopy for extraction and estimation of polyphenols from Basil seeds, Red seeds, Sesame seeds and Ajwan seeds

    Science.gov (United States)

    Mabood, Fazal; Gilani, Syed Abdullah; Hussain, Javid; Alshidani, Sulaiman; Alghawi, Said; Albroumi, Mohammed; Alameri, Saif; Jabeen, Farah; Hussain, Zahid; Al-Harrasi, Ahmed; Al Abri, Zahra K. M.; Farooq, Saima; Naureen, Zakira; Hamaed, Ahmad; Rasul Jan, M.; Shah, Jasmin

    2017-05-01

    New experimental designs for the extraction of polyphenols from different seeds including Basil seed, Red seed, Sesame seeds and Ajwan seeds were investigated. Four variables the concentration and volume of methanol and NaOH solutions as well as the temperature and time of extraction were varied to see their effect on total phenol extraction. The temperature was varied in the range from 25 °C to 200 °C while the time in the range from 30 to 200 minutes. Response surface methodology was used to optimize the extraction parameters. The estimation of polyphenols was measured through phenols reduction UV-Vis spectroscopic method of phosphotungstic-phosphomolybdic acids (Folin-Ciocalteu's reagent). Calibration curve was made by using tannic acid as a polyphenols standard in the concentration range from 0.1 to 10 ppm. The regression line obtained shows the value of correlation coefficient i.e. R = 0.930 and Root mean square error of cross validation (RMSEC) value of 0.0654. The Basil seeds were found containing the highest amount of total phenols i.e. 785.76 mg/100 g. While the Sesame seeds having the least amount i.e. 33.08 mg/100 g. The Ajwan seeds and the Red seeds are containing the medium amounts i.e. 379 mg/100 g and 220.54 mg/100 g respectively.

  13. New design of experiment combined with UV-Vis spectroscopy for extraction and estimation of polyphenols from Basil seeds, Red seeds, Sesame seeds and Ajwan seeds.

    Science.gov (United States)

    Mabood, Fazal; Gilani, Syed Abdullah; Hussain, Javid; Alshidani, Sulaiman; Alghawi, Said; Albroumi, Mohammed; Alameri, Saif; Jabeen, Farah; Hussain, Zahid; Al-Harrasi, Ahmed; Al Abri, Zahra K M; Farooq, Saima; Naureen, Zakira; Hamaed, Ahmad; Rasul Jan, M; Shah, Jasmin

    2017-05-05

    New experimental designs for the extraction of polyphenols from different seeds including Basil seed, Red seed, Sesame seeds and Ajwan seeds were investigated. Four variables the concentration and volume of methanol and NaOH solutions as well as the temperature and time of extraction were varied to see their effect on total phenol extraction. The temperature was varied in the range from 25°C to 200°C while the time in the range from 30 to 200minutes. Response surface methodology was used to optimize the extraction parameters. The estimation of polyphenols was measured through phenols reduction UV-Vis spectroscopic method of phosphotungstic-phosphomolybdic acids (Folin-Ciocalteu's reagent). Calibration curve was made by using tannic acid as a polyphenols standard in the concentration range from 0.1 to 10ppm. The regression line obtained shows the value of correlation coefficient i.e. R=0.930 and Root mean square error of cross validation (RMSEC) value of 0.0654. The Basil seeds were found containing the highest amount of total phenols i.e. 785.76mg/100g. While the Sesame seeds having the least amount i.e. 33.08mg/100g. The Ajwan seeds and the Red seeds are containing the medium amounts i.e. 379mg/100g and 220.54mg/100g respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Anthropogenic signature of sediment organic matter probed by UV-Visible and fluorescence spectroscopy and the association with heavy metal enrichment.

    Science.gov (United States)

    He, Wei; Lee, Jong-Hyun; Hur, Jin

    2016-05-01

    Sediment organic matter (SOM) was extracted in an alkaline solution from 43 stream sediments in order to explore the anthropogenic signatures. The SOM spectroscopic characteristics including excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC) were compared for five sampling site groups classified by the anthropogenic variables of land use, population density, the loadings of organics and nutrients, and metal enrichment. The conventional spectroscopic characteristics including specific UV absorbance, absorbance ratio, and humification index did not properly discriminate among the different cluster groups except in the case of metal enrichment. Of the four decomposed PARAFAC components, humic-like and tryptophan-like fluorescence responded negatively and positively, respectively, to increasing degrees of the anthropogenic variables except for land use. The anthropogenic enrichment of heavy metals was positively associated with the abundance of tryptophan-like component. In contrast, humic-like component, known to be mostly responsible for metal binding, exhibited a decreasing trend corresponding with metal enrichment. These conflicting trends can be attributed to the overwhelmed effects of the coupled discharges of heavy metals and organic pollutants into sediments. Our study suggests that the PARAFAC components can be used as functional signatures to probe the anthropogenic influences on sediments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. ISPyB: an information management system for synchrotron macromolecular crystallography.

    Science.gov (United States)

    Delagenière, Solange; Brenchereau, Patrice; Launer, Ludovic; Ashton, Alun W; Leal, Ricardo; Veyrier, Stéphanie; Gabadinho, José; Gordon, Elspeth J; Jones, Samuel D; Levik, Karl Erik; McSweeney, Seán M; Monaco, Stéphanie; Nanao, Max; Spruce, Darren; Svensson, Olof; Walsh, Martin A; Leonard, Gordon A

    2011-11-15

    Individual research groups now analyze thousands of samples per year at synchrotron macromolecular crystallography (MX) resources. The efficient management of experimental data is thus essential if the best possible experiments are to be performed and the best possible data used in downstream processes in structure determination pipelines. Information System for Protein crystallography Beamlines (ISPyB), a Laboratory Information Management System (LIMS) with an underlying data model allowing for the integration of analyses down-stream of the data collection experiment was developed to facilitate such data management. ISPyB is now a multisite, generic LIMS for synchrotron-based MX experiments. Its initial functionality has been enhanced to include improved sample tracking and reporting of experimental protocols, the direct ranking of the diffraction characteristics of individual samples and the archiving of raw data and results from ancillary experiments and post-experiment data processing protocols. This latter feature paves the way for ISPyB to play a central role in future macromolecular structure solution pipelines and validates the application of the approach used in ISPyB to other experimental techniques, such as biological solution Small Angle X-ray Scattering and spectroscopy, which have similar sample tracking and data handling requirements.

  16. Macromolecular crystallography beamline X25 at the NSLS

    Energy Technology Data Exchange (ETDEWEB)

    Héroux, Annie; Allaire, Marc; Buono, Richard; Cowan, Matthew L.; Dvorak, Joseph; Flaks, Leon; LaMarra, Steven; Myers, Stuart F.; Orville, Allen M.; Robinson, Howard H.; Roessler, Christian G.; Schneider, Dieter K.; Shea-McCarthy, Grace; Skinner, John M.; Skinner, Michael; Soares, Alexei S.; Sweet, Robert M.; Berman, Lonny E., E-mail: berman@bnl.gov [Brookhaven National Laboratory, PO Box 5000, Upton, NY 11973-5000 (United States)

    2014-04-08

    A description of the upgraded beamline X25 at the NSLS, operated by the PXRR and the Photon Sciences Directorate serving the Macromolecular Crystallography community, is presented. Beamline X25 at the NSLS is one of the five beamlines dedicated to macromolecular crystallography operated by the Brookhaven National Laboratory Macromolecular Crystallography Research Resource group. This mini-gap insertion-device beamline has seen constant upgrades for the last seven years in order to achieve mini-beam capability down to 20 µm × 20 µm. All major components beginning with the radiation source, and continuing along the beamline and its experimental hutch, have changed to produce a state-of-the-art facility for the scientific community.

  17. Macromolecular crystallography beamline X25 at the NSLS

    International Nuclear Information System (INIS)

    Héroux, Annie; Allaire, Marc; Buono, Richard; Cowan, Matthew L.; Dvorak, Joseph; Flaks, Leon; LaMarra, Steven; Myers, Stuart F.; Orville, Allen M.; Robinson, Howard H.; Roessler, Christian G.; Schneider, Dieter K.; Shea-McCarthy, Grace; Skinner, John M.; Skinner, Michael; Soares, Alexei S.; Sweet, Robert M.; Berman, Lonny E.

    2014-01-01

    A description of the upgraded beamline X25 at the NSLS, operated by the PXRR and the Photon Sciences Directorate serving the Macromolecular Crystallography community, is presented. Beamline X25 at the NSLS is one of the five beamlines dedicated to macromolecular crystallography operated by the Brookhaven National Laboratory Macromolecular Crystallography Research Resource group. This mini-gap insertion-device beamline has seen constant upgrades for the last seven years in order to achieve mini-beam capability down to 20 µm × 20 µm. All major components beginning with the radiation source, and continuing along the beamline and its experimental hutch, have changed to produce a state-of-the-art facility for the scientific community

  18. Real-time UV-visible spectroscopy analysis of purple membrane-polyacrylamide film formation taking into account Fano line shapes and scattering.

    Science.gov (United States)

    Gomariz, María; Blaya, Salvador; Acebal, Pablo; Carretero, Luis

    2014-01-01

    We theoretically and experimentally analyze the formation of thick Purple Membrane (PM) polyacrylamide (PA) films by means of optical spectroscopy by considering the absorption of bacteriorhodopsin and scattering. We have applied semiclassical quantum mechanical techniques for the calculation of absorption spectra by taking into account the Fano effects on the ground state of bacteriorhodopsin. A model of the formation of PM-polyacrylamide films has been proposed based on the growth of polymeric chains around purple membrane. Experimentally, the temporal evolution of the polymerization process of acrylamide has been studied as function of the pH solution, obtaining a good correspondence to the proposed model. Thus, due to the formation of intermediate bacteriorhodopsin-doped nanogel, by controlling the polymerization process, an alternative methodology for the synthesis of bacteriorhodopsin-doped nanogels can be provided.

  19. Catalytic effects of silver plasmonic nanoparticles on the redox reaction leading to ABTS˙+ formation studied using UV-visible and Raman spectroscopy.

    Science.gov (United States)

    Garcia-Leis, A; Jancura, D; Antalik, M; Garcia-Ramos, J V; Sanchez-Cortes, S; Jurasekova, Z

    2016-09-29

    ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a compound extensively employed to evaluate the free radical trapping capacity of antioxidant agents and complex mixtures such as biological fluids or foods. This evaluation is usually performed by using a colourimetric experiment, where preformed ABTS radical cation (ABTS˙ + ) molecules are reduced in the presence of an antioxidant causing an intensity decrease of the specific ABTS˙ + UV-visible absorption bands. In this work we report a strong effect of silver plasmonic nanoparticles (Ag NPs) on ABTS leading to the formation of ABTS˙ + . The reaction of ABTS with Ag NPs has been found to be dependent on the interfacial and plasmonic properties of NPs. Specifically, this reaction is pronounced in the presence of spherical nanoparticles prepared by the reduction of silver nitrate with hydroxylamine (AgH) and in the case of star-shaped silver nanoparticles (AgNS). On the other hand, spherical nanoparticles prepared by the reduction of silver nitrate with citrate apparently do not react with ABTS. Additionally, the formation of ABTS˙ + is investigated by surface-enhanced Raman scattering (SERS) and the assignment of the most intense vibrational bands of this compound is performed. The SERS technique enables us to detect this radical cation at very low concentrations of ABTS (∼2 μM). Altogether, these findings allow us to suggest the use of ABTS/Ag NPs-systems as reliable and easy going substrates to test the antioxidant capacity of various compounds, even at concentrations much lower than those usually used in the spectrophotometric assays. Moreover, we have suggested that ABTS could be employed as a suitable agent to investigate the interfacial and plasmonic properties of the metal nanoparticles and, thus, to characterize the nanoparticle metal systems employed for various purposes.

  20. Direct spectral analysis of tea samples using 266 nm UV pulsed laser-induced breakdown spectroscopy and cross validation of LIBS results with ICP-MS.

    Science.gov (United States)

    Gondal, M A; Habibullah, Y B; Baig, Umair; Oloore, L E

    2016-05-15

    Tea is one of the most common and popular beverages spanning vast array of cultures all over the world. The main nutritional benefits of drinking tea are its anti-oxidant properties, presumed protection against certain cancers, inhibition of inflammation and possible protective effects against diabetes. Laser induced breakdown spectrometer (LIBS) was assembled as a powerful tool for qualitative and quantitative analysis of various brands of tea samples using 266 nm pulsed UV laser. LIBS spectra for six brands of tea samples in the wavelength range of 200-900 nm was recorded and all elements present in our tea samples were identified. The major toxic elements detected in several brands of tea samples were bromine, chromium and minerals like iron, calcium, potassium and silicon. The spectral assignment was conducted prior to the determination of concentration of each element. For quantitative analysis, calibration curves were drawn for each element using standard samples prepared in known concentration in the tea matrix. The plasma parameters (electron temperature and electron density) were also determined prior to the tea samples spectroscopic analysis. The concentration of iron, chromium, potassium, bromine, copper, silicon and calcium detected in all tea samples was between 378-656, 96-124, 1421-6785, 99-1476, 17-36, 2-11 and 92-130 mg L(-1) respectively. The limits of detection estimated for Fe, Cr, K, Br, Cu, Si, Ca in tea samples were 22, 12, 14, 11, 6, 1 and 12 mg L(-1) respectively. To further confirm the accuracy of our LIBS results, we determined the concentration of each element present in tea samples by using standard analytical technique like ICP-MS. The concentrations detected with our LIBS system are in excellent agreement with ICP-MS results. The system assembled for spectral analysis in this work could be highly applicable for testing the quality and purity of food and also pharmaceuticals products. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Native sulfur/chlorine SAD phasing for serial femtosecond crystallography

    International Nuclear Information System (INIS)

    Nakane, Takanori; Song, Changyong; Suzuki, Mamoru; Nango, Eriko; Kobayashi, Jun; Masuda, Tetsuya; Inoue, Shigeyuki; Mizohata, Eiichi; Nakatsu, Toru; Tanaka, Tomoyuki; Tanaka, Rie; Shimamura, Tatsuro; Tono, Kensuke; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Yabashi, Makina; Nureki, Osamu; Iwata, So; Sugahara, Michihiro

    2015-01-01

    Sulfur SAD phasing facilitates the structure determination of diverse native proteins using femtosecond X-rays from free-electron lasers via serial femtosecond crystallography. Serial femtosecond crystallography (SFX) allows structures to be determined with minimal radiation damage. However, phasing native crystals in SFX is not very common. Here, the structure determination of native lysozyme from single-wavelength anomalous diffraction (SAD) by utilizing the anomalous signal of sulfur and chlorine at a wavelength of 1.77 Å is successfully demonstrated. This sulfur SAD method can be applied to a wide range of proteins, which will improve the determination of native crystal structures

  2. Thermal behavior of H-aggregate in a mixed Langmuir-Blodgett film of merocyanine dye, arachidic acid, and n-octadecane ternary system investigated by UV-visible and IR absorption spectroscopy.

    Science.gov (United States)

    Hirano, Yoshiaki; Tateno, Shinsuke; Yamashita, Yoshihide; Ozaki, Yukihiro

    2008-11-13

    We have investigated the thermal behavior of H-aggregate in a mixed Langmuir-Blodgett (LB) film of the merocyanine dye (MS18)-arachidic acid (C20)- n-octadecane (AL18) ternary system by means of UV-visible and IR absorption spectroscopy in the range from 25 to 250 degrees C with a continuous scan. The results of both UV-visible and IR spectra indicate that the temperature-dependent variation in MS 18 aggregation state is linked not only with the degree of intramolecular charge transfer and the behavior of packing, orientation, conformation, and thermal mobility of the MS18 hydrocarbon chain but also with the presence and absence of AL18. The H-aggregate dissociates from 25 up to 50 degrees C, which is caused by the AL18 evaporation from the mixed LB film and the increment of thermal mobility of the MS18 hydrocarbon chain. From 110 to 160 degrees C, blue-shifted bands, attributed to the oligomeric MS18 aggregation, appear near 515 nm in the MS18-C 20-AL18 ternary system as well. The temperature at which the 515 nm band occurs is identical for both present ternary system and previously investigated MS18-deuterated arachidic acid (C20- d) binary system, and it is in good agreement with the melting point (110 degrees C) of cadmium arachidate (CdC20). Therefore, it is indicated that the driving force which induces the 515 nm band comes from the melting phenomenon of CdC20 molecules which are phase-separated from MS 18 molecules in as-deposited LB films.

  3. Applied Crystallography - Proceedings of the XVth Conference

    Science.gov (United States)

    Morawiec, H.; Ströż, D.

    1993-06-01

    The Table of Contents for the full book PDF is as follows: * Foreword * The International Centre for Diffraction Data and Its Future Developments * The Rietveld Method - A Historical Perspective * Real Structure in Quantitative Powder Diffraction Phase Analysis * Neutron Focusing Optics in Applied Crystallography * The Crystal Structures of Oxygen Deficient Rare Earth Oxides * Short-Range Order in Layer-Structured Ba1-xSrxBi2Nb2O9 Ferroelectrics * Radial Distribution Function as a Tool of Structural Studies on Noncrystalline Materials * Determination of Radial Distribution Function (RDF) of Electrodeposited Cu-Cd Alloys After Annealing * Spheres Packing as a Factor Describing the Local Environment and Structure Stability * X-Ray Stress Measurement of Samples Combined with Diffraction Line Analysis * Phase Stability and Martensitic Transformation in Cu-Zn and Cu-Zn-Al Single Crystals * Order, Defects, Precipitates and the Martensitic Transformation in β Cu-Zn-Al * Effect of γ Precipitates on the Martensitic Transformation in Cu-Zn-Al Alloys * Phase Transitions and Shape Memory Effect in a Thermomechanically Treated NiTi Alloy * Structure of Martensite and Bainite in CuAlMn Alloys * Glass-Ceramics * Mechanism of Texture Formation at the Rolling of Low Stacking Fault Energy Metals and Alloys * Shear Texture of Zinc and the Conditions of Its Occuring * The Development of Texture of ZnAlMg Sheets Depending on Deformation Geometry * Texture Stability of the D.S. NiAlMoCrTi Alloy After Heat Treatment * X-Ray Diffraction Method for Controlling of Texture Evolution in Layers * Texture and Lattice Imperfections Study of Some Low Alloyed Copper Alloys * Selected Examples of the Calculation of the Orientation Distribution Function for Low Crystal and Sample Symmetries * Automatical X-Ray Quantitative Phase Analysis * Application of a PC Computer for Crystallographic Calculations * Electron Diffraction Analysis using a Personal Computer * CA.R.INE Crystallography Version 2

  4. On the near UV photophysics of a phenylalanine residue: conformation-dependent ππ* state deactivation revealed by laser spectroscopy of isolated neutral dipeptides.

    Science.gov (United States)

    Loquais, Yohan; Gloaguen, Eric; Alauddin, Mohammad; Brenner, Valérie; Tardivel, Benjamin; Mons, Michel

    2014-10-28

    The primary step of the near UV photophysics of a phenylalanine residue is investigated in one- and two-color pump-probe R2PI nanosecond experiments carried out on specific conformers of the Ac-Gly-Phe-NH2 molecule and related neutral compounds isolated in a supersonic expansion. Compared to toluene, whose ππ* state photophysics is dominated by intersystem crossing with a lifetime of ∼80 ns at the origin, the first ππ* state of Phe in the peptide environment is systematically found to be shorter-lived. The lifetime at the origin of transition is found to be significantly shortened in the presence of a primary amide (-CONH2) group (20-60 ns, depending on the conformer considered), demonstrating the existence of an additional non-radiative relaxation channel related to this chemical group. The quenching effect induced by the peptide environment is still more remarkable beyond the origin of the ππ* state, since vibronic bands of one of the 4 conformers observed (the 27-ribbon conformation) become barely detectable in the ns R2PI experiment, suggesting a significant conformer-selective lifetime shortening (below 100 ps). These results on dipeptides, which extend previous investigations on shorter Phe-containing molecules (N-Ac-Phe-NH2 and N-Ac-Phe-NH-Me), confirm the existence of conformer-dependent non-radiative deactivation processes, whose characteristic timescales range from tens of ns down to hundreds of ps or below. This dynamics is assigned to two distinct mechanisms: a first one, consistent with an excitation energy transfer from the optically active ππ* state to low-lying amide nπ* excited states accessed through conical intersections, especially in the presence of a C-terminal primary amide group (-CONH2); a second one, responsible for the short lifetimes in 2(7) ribbon structures, would be more specifically triggered by phenyl ring vibrational excitations. Implications in terms of spectroscopic probing of Phe in a peptide environment, especially

  5. ESIPT and photodissociation of 3-hydroxychromone in solution: photoinduced processes studied by static and time-resolved UV/Vis, fluorescence, and IR spectroscopy.

    Science.gov (United States)

    Chevalier, Katharina; Grün, Anneken; Stamm, Anke; Schmitt, Yvonne; Gerhards, Markus; Diller, Rolf

    2013-11-07

    The spectral properties of fluorescence sensors such as 3-hydroxychromone (3-HC) and its derivatives are sensitive to interaction with the surrounding medium as well as to substitution. 3-HC is a prototype system for other derivatives because it is the basic unit of all flavonoides undergoing ESIPT and is not perturbed by a substituent. In this study, the elementary processes and intermediate states in the photocycle of 3-HC as well as its anion were identified and characterized by the use of static and femtosecond time-resolved spectroscopy in different solvents (methylcyclohexane, acetonitrile, ethanol, and water at different pH). Electronic absorption and fluorescence spectra and lifetimes of the intermediate states were obtained for the normal, tautomer and anionic excited state, while mid-IR vibrational spectra yielded structural information on ground and excited states of 3-HC. A high sensitivity on hydrogen-bonding perturbations was observed, leading to photoinduced anion formation in water, while in organic solvents, different processes are suggested, including slow picosecond ESIPT and contribution of the trans-structure excited state or a different stable solvation state with different direction of OH. The formation of the latter could be favored by the lack of a substituent increasing contact points for specific solute-solvent interactions at the hydroxyl group compared to substituted derivatives. The effect of substituents has to be considered for the design of future fluorescence sensors based on 3-HC.

  6. Crystallography and Morphology of MC Carbides in Niobium-Titanium Modified As-Cast HP Alloys

    Science.gov (United States)

    Buchanan, Karl G.; Kral, Milo V.; Bishop, Catherine M.

    2014-07-01

    The microstructures of two as-cast heats of HP alloy stainless steels modified with niobium and titanium were examined with particular attention paid to the interdendritic niobium-titanium-rich carbides formed during solidification of these alloys. Generally, these precipitates obtain a blocky morphology in the as-cast condition. However, the (NbTi)C precipitates may obtain a nodular morphology. To provide further insight to the origin of the two different morphologies obtained by the (NbTi)C precipitates in the HP-NbTi alloy, the microstructure and crystallography of each have been studied in detail using scanning electron microscopy, transmission electron microscopy, various electron diffraction methods (EBSD, SAD, and CBED), and energy-dispersive X-ray spectroscopy.

  7. Crystallography and Morphology of Niobium Carbide in As-Cast HP-Niobium Reformer Tubes

    Science.gov (United States)

    Buchanan, Karl G.; Kral, Milo V.

    2012-06-01

    The microstructures of two as-cast heats of niobium-modified HP stainless steels were characterized. Particular attention was paid to the interdendritic niobium-rich carbides formed during solidification of these alloys. At low magnifications, these precipitates are grouped in colonies of similar lamellae. Higher magnifications revealed that the lamellae actually obtain two distinct morphologies. The type I morphology exhibits broad planar interfaces with a smooth platelike shape. Type II lamellae have undulating interfaces and an overall reticulated shape. To provide further insight into the origin of these two different morphologies, the microstructure and crystallography of each have been studied in detail using high resolution scanning electron microscopy, transmission electron microscopy, various electron diffraction methods (electron backscatter diffraction (EBSD), selected area diffraction (SAD), and convergent beam electron diffraction (CBED)), and energy dispersive X-ray spectroscopy.

  8. Synthesis, x-ray crystallography and leishmanicidal activity of benzimidazolinyl piperidine derivative

    International Nuclear Information System (INIS)

    Saify, Z.S.; Begum, N.; Yousuf, S.; Ashraf, S.

    2014-01-01

    Protozoan parasites of the Leishmania genus are the main cause of vector-borne disease leishmaniasis throughout the world. It is caused by at least 17 different species of protozoan Leishmania and transmitted by the bite of infected sand flies. Leishmaniasis could be fatal. Present drugs have limitations to cure it due to the development of drug resistance. Hence, to design an effective leishmanicidal agent would be of great interest. Benzimidazolinyl piperidine has served as potential target due to a vast range of biological activities. In the present study a new 4-(2-keto-1-benzimidazolinyl)piperidine derivative, 1-(2-(4-fluorophenyl)-2-oxoethyl)-4-(2-oxo-2,3-dihydro-1H-benzo(d)imidazol) piperidinium bromide has been synthesized and characterized by X-ray crystallography, 1D and 2D NMR spectroscopy. Evaluation by in vitro leishmanicidal assay showed good activity. (author)

  9. Micropolarity and Hydrogen-Bond Donor Ability of Environmentally Friendly Anionic Reverse Micelles Explored by UV/Vis Absorption of a Molecular Probe and FTIR Spectroscopy.

    Science.gov (United States)

    Girardi, Valeria R; Silber, Juana J; Falcone, Ruben Darío; Correa, N Mariano

    2018-03-19

    In the present work we show how two biocompatible solvents, methyl laurate (ML) and isopropyl myristate (IPM), can be used as a less toxic alternative to replace the nonpolar component in a sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs) formulation. In this sense, the micropolarity and the hydrogen-bond ability of the interface were monitored through the use of the solvatochromism of a molecular probe (1-methyl-8-oxyquinolinium betaine, QB) and Fourier transform infrared spectroscopy (FTIR). Our results demonstrate that the micropolarity sensed by QB in ML RMs is lower than in IPM RMs. Additionally, the water molecules form stronger H-bond interactions with the polar head of AOT in ML than in IPM. By FTIR was revealed that more water molecules interact with the interface in ML/AOT RMs. On the other hand, for AOT RMs generated in IPM, the weaker water-surfactant interaction allows the water molecules to establish hydrogen bonds with each other trending to bulk water more easily than in ML RMs, a consequence of the dissimilar penetration of nonpolar solvents into the interfacial region. The penetration process is strongly controlled by the polarity and viscosity of the external solvents. All of these results allow us to characterize these biocompatible systems, providing information about interfacial properties and how they can be altered by changing the external solvent. The ability of the nontoxic solvent to penetrate or not into the AOT interface produces a new interface with attractive properties. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Mehder, A O; Habibullah, Y B; Gondal, M A; Baig, Umair

    2016-08-01

    Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge. Copyright © 2016 Elsevier B

  11. Fab Chaperone-Assisted RNA Crystallography (Fab CARC).

    Science.gov (United States)

    Sherman, Eileen; Archer, Jennifer; Ye, Jing-Dong

    2016-01-01

    Recent discovery of structured RNAs such as ribozymes and riboswitches shows that there is still much to learn about the structure and function of RNAs. Knowledge learned can be employed in both biochemical research and clinical applications. X-ray crystallography gives unparalleled atomic-level structural detail from which functional inferences can be deduced. However, the difficulty in obtaining high-quality crystals and their phasing information make it a very challenging task. RNA crystallography is particularly arduous due to several factors such as RNA's paucity of surface chemical diversity, lability, repetitive anionic backbone, and flexibility, all of which are counterproductive to crystal packing. Here we describe Fab chaperone assisted RNA crystallography (CARC), a systematic technique to increase RNA crystallography success by facilitating crystal packing as well as expediting phase determination through molecular replacement of conserved Fab domains. Major steps described in this chapter include selection of a synthetic Fab library displayed on M13 phage against a structured RNA crystallization target, ELISA for initial choice of binding Fabs, Fab expression followed by protein A affinity then cation exchange chromatography purification, final choice of Fab by binding specificity and affinity as determined by a dot blot assay, and lastly gel filtration purification of a large quantity of chosen Fabs for crystallization.

  12. Crystallography of the Sb-Te-Ni system

    Czech Academy of Sciences Publication Activity Database

    Laufek, F.; Drábek, M.; Skála, Roman; Císařová, I.

    2005-01-01

    Roč. 12, č. 2 (2005), s. 153-154 ISSN 1211-5894 Grant - others:GAUK(CZ) 43-203391 Institutional research plan: CEZ:AV0Z30130516 Keywords : crystallography * antimony * tellurium Subject RIV: DB - Geology ; Mineralogy http:// xray .cz/ms/bul2005-2/student3.pdf

  13. A high-pressure MWPC detector for crystallography

    DEFF Research Database (Denmark)

    Ortuno-Prados, F.; Bazzano, A.; Berry, A.

    1999-01-01

    The application of the Multi-Wire Proportional Counter (MWPC) as a potential detector for protein crystallography and other wide-angle diffraction experiments is presented. Electrostatic problems found with our large area MWPC when operated at high pressure are discussed. We suggest that a solution...

  14. Analytical applications of spectroscopy

    International Nuclear Information System (INIS)

    Creaser, C.S.

    1988-01-01

    This book provides an up to date overview of recent developments in analytical spectroscopy, with a particular emphasis on the common themes of chromatography - spectroscopy combinations, Fourier transform methods, and data handling techniques, which have played an increasingly important part in the development of all spectroscopic techniques. The book contains papers originally presented at a conference entitled 'Spectroscopy Across The Spectrum' held jointly with the first 'International Near Infrared Spectroscopy Conference' at the University of East Anglia, Norwich, UK, in July 1987, which have been edited and rearranged with some additional material. Each section includes reviews of key areas of current research as well as short reports of new developments. The fields covered are: Near Infrared Spectroscopy; Infrared Spectroscopy; Mass Spectroscopy; NMR Spectroscopy; Atomic and UV/Visible Spectroscopy; Chemometrics and Data Analysis. (author)

  15. The role of zinc deficiency-induced changes in the phospholipid-protein balance of blood serum in animal depression model by Raman, FTIR and UV-vis spectroscopy.

    Science.gov (United States)

    Depciuch, J; Sowa-Kućma, M; Nowak, G; Szewczyk, B; Doboszewska, U; Parlinska-Wojtan, M

    2017-05-01

    Depression is a serious mental illness. To study the mechanisms of diseases and search for new, more effective therapies, animal models are used. Unfortunately, none of the available models does reflect all symptoms of depression. Zinc deficiency is proposed as a new animal model of depression. However, it has not been yet validated in a detailed manner. Recently, spectroscopic techniques are increasingly being used both in clinical and preclinical studies. Here we examined the effect of zinc deficiency and amitryptyline treatment on the phospholipid - protein balance in the blood serum of rats using Raman, Fourier Transform Infra Red (FTIR) and UV-vis technique. Male Sprague Dawley rats were fed with a zinc ample diet (ZnA, 50mg Zn/kg) or a zinc deficient diet (ZnD, 3mg Zn/kg) for 4 weeks. Then amitriptyline administration (AMI, 10mg/kg, i.p.) was started. After injecting the drug for 2-weeks, blood samples were collected and analyzed. It was found that zinc deficiency decreases both the level of phospholipids and proteins and also causes structural changes in their structures. In the ZnD group amitriptyline treatment influenced the protein level and structure. UV-vis spectroscopy combined with the second derivative calculated from the FTIR spectra provided information that the proteins in blood serum of rat fed with a low Zn diet regain their intact structure after amitriptyline medication. Simultaneously, the antidepressant therapy did not have any effect on the level of phospholipids in this group of rats. Additionally, our results show, that amitriptyline administration can change the structure of phospholipids in rats subjected to zinc ample diet. This altered structure of phospholipids was identified as shortening of carbon chains. Our findings indicate that the decreased level of zinc may be the cause of depressive disorders, as it leads to changes in the phospholipid-protein balance necessary for the proper functioning of the body. This study also shows

  16. Laser spectroscopy

    CERN Document Server

    Demtröder, Wolfgang

    2008-01-01

    Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., frequency doubling in external cavities, reliable cw-parametric oscillators, tunable narrow-band UV sources, more sensitive detection techniques, tunable femtosecond and sub-femtosecond lasers (X-ray region and the attosecond range), control of atomic and molecular excitations, frequency combs able to synchronize independent femtosecond lasers, coherent matter waves, and still more applications in chemical analysis, medical diagnostics, and engineering.

  17. Lipidic cubic phase serial millisecond crystallography using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Przemyslaw Nogly

    2015-03-01

    Full Text Available Lipidic cubic phases (LCPs have emerged as successful matrixes for the crystallization of membrane proteins. Moreover, the viscous LCP also provides a highly effective delivery medium for serial femtosecond crystallography (SFX at X-ray free-electron lasers (XFELs. Here, the adaptation of this technology to perform serial millisecond crystallography (SMX at more widely available synchrotron microfocus beamlines is described. Compared with conventional microcrystallography, LCP-SMX eliminates the need for difficult handling of individual crystals and allows for data collection at room temperature. The technology is demonstrated by solving a structure of the light-driven proton-pump bacteriorhodopsin (bR at a resolution of 2.4 Å. The room-temperature structure of bR is very similar to previous cryogenic structures but shows small yet distinct differences in the retinal ligand and proton-transfer pathway.

  18. A readout system for X-ray powder crystallography

    CERN Document Server

    Loukas, D; Pavlidis, A; Karvelas, E; Psycharis, K; Misiakos, V; Mousa, J; Dre, C

    2000-01-01

    A system for capturing and processing data, from radiation detectors, in the field of X-ray crystallography has been developed. The system includes a custom-made mixed analog-digital 16-channel VLSI circuit in 50 mu m pitch. Each channel comprises a charge amplifier, a shaper, a comparator and a 21-bit counter. The circuit can be scaled in a daisy chain configuration. Data acquisition is performed with a custom made PCI card while the control software is developed with Visual C++ under the MS Windows NT environment. Performance of a fully operational system, in terms of electronic noise, statistical variations and data capture speed is presented. The noise level permits counting of X-rays down to 8 keV while the counting capability is in excess of 200 kHz. The system is intended for X-ray crystallography with silicon detectors.

  19. Structural characterization of native high-methoxylated pectin using nuclear magnetic resonance spectroscopy and ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Comparative use of 2,5-dihydroxybenzoic acid and nor-harmane as UV-MALDI matrices.

    Science.gov (United States)

    Monge, María Eugenia; Negri, R Martín; Kolender, Adriana A; Erra-Balsells, Rosa

    2007-01-01

    The successful analysis by ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS) of native and hydrolyzed high-methoxylated pectin samples is described. In order to find the optimal conditions for UV-MALDI-TOF MS analysis several experimental variables were studied such as: different UV-MALDI matrices (nor-harmane, 2,5-dihydroxybenzoic acid), sample preparation methods (mixture, sandwich), inorganic salt addition (doping salts, NaCl, KCl, NH(4)Cl), ion mode (positive, negative), linear and reflectron mode, etc. nor-Harmane has never been used as a UV-MALDI matrix for the analysis of pectins but its use avoids pre-treatment of the sample, such as an enzymatic digestion or an acid hydrolysis, and there is no need to add salts, making the analysis easier and faster. This study suggested an alternative way of analyzing native high-methoxylated pectins, with UV-MALDI-TOF MS, by using nor-harmane as the matrix in negative ion mode. The analysis by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy of the native and hydrolyzed pectin is also briefly described. Copyright (c) 2007 John Wiley & Sons, Ltd.

  20. Native sulfur/chlorine SAD phasing for serial femtosecond crystallography.

    Science.gov (United States)

    Nakane, Takanori; Song, Changyong; Suzuki, Mamoru; Nango, Eriko; Kobayashi, Jun; Masuda, Tetsuya; Inoue, Shigeyuki; Mizohata, Eiichi; Nakatsu, Toru; Tanaka, Tomoyuki; Tanaka, Rie; Shimamura, Tatsuro; Tono, Kensuke; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Yabashi, Makina; Nureki, Osamu; Iwata, So; Sugahara, Michihiro

    2015-12-01

    Serial femtosecond crystallography (SFX) allows structures to be determined with minimal radiation damage. However, phasing native crystals in SFX is not very common. Here, the structure determination of native lysozyme from single-wavelength anomalous diffraction (SAD) by utilizing the anomalous signal of sulfur and chlorine at a wavelength of 1.77 Å is successfully demonstrated. This sulfur SAD method can be applied to a wide range of proteins, which will improve the determination of native crystal structures.

  1. A history of experimental phasing in macromolecular crystallography

    OpenAIRE

    Isaacs, Neil

    2016-01-01

    It was just over a century ago that W. L. Bragg published a paper describing the first crystal structures to be determined using X-ray diffraction data. These structures were obtained from considerations of X-ray diffraction (Bragg equation), crystallography (crystal lattices and symmetry) and the scattering power of different atoms. Although W. H. Bragg proposed soon afterwards, in 1915, that the periodic electron density in crystals could be analysed using Fourier transforms, it took some d...

  2. PRIGo: a new multi-axis goniometer for macromolecular crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Waltersperger, Sandro; Olieric, Vincent, E-mail: vincent.olieric@psi.ch; Pradervand, Claude [Paul Scherrer Institute, Villigen PSI (Switzerland); Glettig, Wayne [Centre Suisse d’Electronique et Microtechnique SA, Neuchâtel 2002 (Switzerland); Salathe, Marco; Fuchs, Martin R.; Curtin, Adrian; Wang, Xiaoqiang; Ebner, Simon; Panepucci, Ezequiel; Weinert, Tobias [Paul Scherrer Institute, Villigen PSI (Switzerland); Schulze-Briese, Clemens [Dectris Ltd, Baden 5400 (Switzerland); Wang, Meitian, E-mail: vincent.olieric@psi.ch [Paul Scherrer Institute, Villigen PSI (Switzerland)

    2015-05-09

    The design and performance of the new multi-axis goniometer PRIGo developed at the Swiss Light Source at Paul Scherrer Institute is described. The Parallel Robotics Inspired Goniometer (PRIGo) is a novel compact and high-precision goniometer providing an alternative to (mini-)kappa, traditional three-circle goniometers and Eulerian cradles used for sample reorientation in macromolecular crystallography. Based on a combination of serial and parallel kinematics, PRIGo emulates an arc. It is mounted on an air-bearing stage for rotation around ω and consists of four linear positioners working synchronously to achieve x, y, z translations and χ rotation (0–90°), followed by a ϕ stage (0–360°) for rotation around the sample holder axis. Owing to the use of piezo linear positioners and active correction, PRIGo features spheres of confusion of <1 µm, <7 µm and <10 µm for ω, χ and ϕ, respectively, and is therefore very well suited for micro-crystallography. PRIGo enables optimal strategies for both native and experimental phasing crystallographic data collection. Herein, PRIGo hardware and software, its calibration, as well as applications in macromolecular crystallography are described.

  3. Detection of olive oil adulteration by low-field NMR relaxometry and UV-Vis spectroscopy upon mixing olive oil with various edible oils; Detección de la adulteración de aceite de oliva mediante relaxometría magnética nuclear de campo bajo y espectroscopía UV-Vis sobre mezcla de aceite de oliva con diversos aceites comestibles.

    Energy Technology Data Exchange (ETDEWEB)

    Ok, S.

    2017-07-01

    Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF) proton (1H) nuclear magnetic resonance (NMR) relaxometry and ultra-violet (UV) visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2) curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively. [Spanish] La adulteración del aceite de oliva con sustituyentes menos saludables es una amenaza para la salud pública. En este trabajo, la detección de la adulteración del aceite de oliva se demuestra utilizando tanto relaxometría magnética nuclear de campo bajo (LF) de protones (1H) (RMN) y espectroscopía visible y ultra-violeta (UV). Tres muestras de aceites de oliva con diferentes contenidos en oleico se mezclaron con aceites de almendra, ricino, maíz y sésamo con tres relaciones volumétricas. Además, el de arbequina de California se mezcló con cánola, lino, semilla de uva, cacahuete, soja y aceites de girasol con tres relaciones volumétricas. Las curvas de

  4. A rapid alternative to X-ray crystallography for chiral determination: case studies of vibrational circular dichroism (VCD) to advance drug discovery projects.

    Science.gov (United States)

    Wesolowski, Steven S; Pivonka, Don E

    2013-07-15

    The absolute stereochemistry of chiral drugs is usually established via X-ray crystallography. However, vibrational circular dichroism (VCD) spectroscopy coupled with quantum mechanics simulations offers a rapid alternative to crystallography and is readily applied to both crystalline and non-crystalline samples. VCD is an effective complement to X-ray analysis of drug candidates, and it can be used as a high-throughput means of assessing absolute stereochemistry at all phases of the discovery process (hundreds of assignments per year). The practical implementation (or fee-for-service outsourcing) of VCD and selected case studies are illustrated with an emphasis on providing utility and impact to pharmaceutical discovery programs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Cationic and Anionic Disorder in CZTSSe Kesterite Compounds: A Chemical Crystallography Study.

    Science.gov (United States)

    Bais, Pierre; Caldes, Maria Teresa; Paris, Michaël; Guillot-Deudon, Catherine; Fertey, Pierre; Domengès, Bernadette; Lafond, Alain

    2017-10-02

    The cationic and anionic disorder in the Cu 2 ZnSnSe 4 -Cu 2 ZnSnS 4 (CZTSe-CZTS) system has been investigated through a chemical crystallography approach including X-ray diffraction (in conventional and resonant setup), 119 Sn and 77 Se NMR spectroscopy, and high-resolution transmission electron microscopy (HRTEM) techniques. Single-crystal XRD analysis demonstrates that the studied compounds behave as a solid solution with the kesterite crystal structure in the whole S/(S + Se) composition range. As previously reported for pure sulfide and pure selenide compounds, the 119 Sn NMR spectroscopy study gives clear evidence that the level of Cu/Zn disorder in mixed S/Se compounds depends on the thermal history of the samples (slow cooled or quenched). This conclusion is also supported by the investigation of the 77 Se NMR spectra. The resonant single-crystal XRD technique shows that regardless of the duration of annealing step below the order-disorder critical temperature the ordering is not a long-range phenomenon. Finally, for the very first time, HREM images of pure selenide and mixed S/Se crystals clearly show that these compounds have different microstructures. Indeed, only the mixed S/Se compound exhibits a mosaic-type contrast which could be the sign of short-range anionic order. Calculated images corroborate that HRTEM contrast is highly dependent on the nature of the anion as well as on the local anionic order.

  6. Advances in DUV spectroscopy

    DEFF Research Database (Denmark)

    Buchhave, Preben; Tidemand-Lichtenberg, Peter; Mogensen, Claus Tilsted

    The would-be advantages of deep UV (DUV) spectroscopy are well known, but the potential applications have so far not been fully realized due to technological limitations and, perhaps, lack of bright ideas. However, new components and new knowledge about DUV spectra and spectroscopic methods...... combined with increasing needs for solutions to practical problems in environmental protection, medicine and pollution monitoring promise a new era in DUV spectroscopy. Here we shall review the basis for DUV spectroscopy, both DUV fluorescence and DUV Raman spectroscopy, and describe recent advances...

  7. Spectroscopy for Dummies

    DEFF Research Database (Denmark)

    Lindvold, Lars René

    This presentation will give short introduction to the most pertinent topics of optical spectroscopy. The following topics will be discussed: • The origin of spectra in UV, VIS and IR spectral range • Spectroscopic methods like absorption, luminescence and Raman • Wavelength dispersive optical...... components • Materials for use optical spectroscopy • Spectrometer geometries • Detectors for use in spectrometer • Practical examples of optical spectroscopy The objective of this presentation is to give the audience a good feel for the range of possibilities that optical spectroscopy can provide....

  8. Contribution of X-ray crystallography in energy related problems

    International Nuclear Information System (INIS)

    Majid, C.A.; Hussain, M.A.

    1995-01-01

    Crystallography is concerned with the study of the structure of matter at the atomic level in condensed state. The great practical importance of scientific knowledge of the structure of solid is self evident when consideration is given to the definition of desired physical and chemical properties. The strength of steel girders, the corrosion of alloys, the plasticity of lime, the wearing properties of case hardness steel, the dielectric capacity of materials, the lubricating properties of long chain paraffin's or of graphite, the stretching of rubber and innumerable other practical phenomena of every day life depend upon ultimate structure of these materials. To understand function to control, manipulate and best utilize their properties, and to produce materials with properties meeting a desired set of specification it is essential to understand thoroughly both the characteristics and origin of each property. Origins of materials properties lie in a combination of natural laws with the detailed structure and composition of materials, i.e. the choice, location, bonding, etc. of every atom in the material object. Therefore, to understand their various properties, it is important to explore the structure property relationship in materials. X-ray crystallography is not only helping to develop new materials having desired properties, but also in improving existing materials. Radiation effects, electrolytes, superconductors and catalysts etc. are just a few examples of many areas where crystallography is helping. With the invent of new radiation sources like synchrotron and new detectors materials and techniques, this almost 80 years old discipline continues to capture the interest of solid state physicists and chemists alike. (author)

  9. "XANSONS for COD": a new small BOINC project in crystallography

    Science.gov (United States)

    Neverov, Vladislav S.; Khrapov, Nikolay P.

    2018-04-01

    "XANSONS for COD" (http://xansons4cod.com) is a new BOINC project aimed at creating the open-access database of simulated x-ray and neutron powder diffraction patterns for nanocrystalline phase of materials from the collection of the Crystallography Open Database (COD). The project uses original open-source software XaNSoNS to simulate diffraction patterns on CPU and GPU. This paper describes the scientific problem this project solves, the project's internal structure, its operation principles and organization of the final database.

  10. Crystallography of lath martensite and stabilization of retained austenite

    Energy Technology Data Exchange (ETDEWEB)

    Sarikaya. M.

    1982-10-01

    TEM was used to study the morphology and crystallography of lath martensite in low and medium carbon steels in the as-quenched and 200/sup 0/C tempered conditions. The steels have microduplex structures of dislocated lath martensite and continuous thin films of retained austenite at the lath interfaces. Stacks of laths form the packets which are derived from different (111) variants of the same austenite grain. The residual parent austenite enables microdiffraction experiments with small electron beam spot sizes for the orientation relationships (OR) between austenite and martensite. All three most commonly observed ORs, namely Kurdjumov-Sachs, Nishiyama-Wassermann, and Greninger-Troiano, operate within the same sample.

  11. Crystallography of lath martensite and stabilization of retained austenite

    International Nuclear Information System (INIS)

    Sarikaya, M.

    1982-10-01

    TEM was used to study the morphology and crystallography of lath martensite in low and medium carbon steels in the as-quenched and 200 0 C tempered conditions. The steels have microduplex structures of dislocated lath martensite and continuous thin films of retained austenite at the lath interfaces. Stacks of laths form the packets which are derived from different [111] variants of the same austenite grain. The residual parent austenite enables microdiffraction experiments with small electron beam spot sizes for the orientation relationships (OR) between austenite and martensite. All three most commonly observed ORs, namely Kurdjumov-Sachs, Nishiyama-Wassermann, and Greninger-Troiano, operate within the same sample

  12. Protein Crystallography: A 'Must' Technology for Drug Design

    International Nuclear Information System (INIS)

    Matsuzaki, Takao

    2004-01-01

    The history of drug-related protein crystallography and drug design is reviewed to show that 'Lead Generation' is high-lighted in the pharmaceutical industry nowadays. A new drug design method has been developed. The method gave very high success rate; 10-60 % gave < 100 μM, 90 % gave < 10 mM. The crystal structures of drug-protein complexes have become even more important to give solid experimental bases for e.g. 1,000 designed structures and to find the new mechanisms of drug action

  13. Protein crystal growth studies at the Center for Macromolecular Crystallography

    International Nuclear Information System (INIS)

    DeLucas, Lawrence J.; Long, Marianna M.; Moore, Karen M.; Harrington, Michael; McDonald, William T.; Smith, Craig D.; Bray, Terry; Lewis, Johanna; Crysel, William B.; Weise, Lance D.

    2000-01-01

    The Center for Macromolecular Crystallography (CMC) has been involved in fundamental studies of protein crystal growth (PCG) in microgravity and in our earth-based laboratories. A large group of co-investigators from academia and industry participated in these experiments by providing protein samples and by performing the x-ray crystallographic analysis. These studies have clearly demonstrated the usefulness of a microgravity environment for enhancing the quality and size of protein crystals. Review of the vapor diffusion (VDA) PCG results from nineteen space shuttle missions is given in this paper

  14. P 8: Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by soft X-ray from a laser induced plasma source and/or UV-VIS laser

    International Nuclear Information System (INIS)

    Bruza, P.; Fidler, V.; Nikl, M.

    2010-01-01

    The design and use of a novel, table-top UV-VIS luminescence spectrometer with two excitation sources is described: a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of about 4 ns duration, and a conventional N 2 pulse laser excitation at 337 nm (or any other UV-VIS pulse laser excitation). The XUV plasma source generates photons of either quasi-monochromatic (N target, E = 430 eV) or wide (Ar target, E = 200 ∼ 600 eV) spectral range. A combination of both X-ray/XUV and UV-VIS excitation in one experimental apparatus allows to perform comparative luminescence spectra and kinetics measurements under the same experimental conditions. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu 3 Al 5 O 12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of doped Ce 3+ ions was studied under XUV 430 eV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3,68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d transition of Ce 3+ is directly excited. Furthermore, LuAG:Ce single crystals and single crystalline films luminescence decay profiles are compared and discussed. (authors)

  15. JBluIce-EPICS control system for macromolecular crystallography

    International Nuclear Information System (INIS)

    Stepanov, S.; Makarov, O.; Hilgart, M.; Pothineni, S.; Urakhchin, A.; Devarapalli, S.; Yoder, D.; Becker, M.; Ogata, C.; Sanishvili, R.; Nagarajan, V.; Smith, J.L.; Fischetti, R.F.

    2011-01-01

    The trio of macromolecular crystallography beamlines constructed by the General Medicine and Cancer Institutes Collaborative Access Team (GM/CA-CAT) in Sector 23 of the Advanced Photon Source (APS) have been in growing demand owing to their outstanding beam quality and capacity to measure data from crystals of only a few micrometres in size. To take full advantage of the state-of-the-art mechanical and optical design of these beamlines, a significant effort has been devoted to designing fast, convenient, intuitive and robust beamline controls that could easily accommodate new beamline developments. The GM/CA-CAT beamline controls are based on the power of EPICS for distributed hardware control, the rich Java graphical user interface of Eclipse RCP and the task-oriented philosophy as well as the look and feel of the successful SSRL BluIce graphical user interface for crystallography. These beamline controls feature a minimum number of software layers, the wide use of plug-ins that can be written in any language and unified motion controls that allow on-the-fly scanning and optimization of any beamline component. This paper describes the ways in which BluIce was combined with EPICS and converted into the Java-based JBluIce, discusses the solutions aimed at streamlining and speeding up operations and gives an overview of the tools that are provided by this new open-source control system for facilitating crystallographic experiments, especially in the field of microcrystallography.

  16. A beamline for macromolecular crystallography at the Advanced Light Source

    International Nuclear Information System (INIS)

    Padmore, H.A.; Earnest, T.; Kim, S.H.; Thompson, A.C.; Robinson, A.L.

    1994-08-01

    A beamline for macromolecular crystallography has been designed for the ALS. The source will be a 37-pole wiggler with a, 2-T on-axis peak field. The wiggler will illuminate three beamlines, each accepting 3 mrad of horizontal aperture. The central beamline will primarily be used for multiple-wavelength anomalous dispersion measurements in the wavelength range from 4 to 0.9 angstrom. The beamline optics will comprise a double-crystal monochromator with a collimating pre-mirror and a double-focusing mirror after the monochromator. The two side stations will be used for fixed-wavelength experiments within the wavelength range from 1.5 to 0.95 angstrom. The optics will consist of a conventional vertically focusing cylindrical mirror followed by an asymmetrically cut curved-crystal monochromator. This paper presents details of the optimization of the wiggler source for crystallography, gives a description of the beamline configuration, and discusses the reasons for the choices made

  17. X-ray crystallography facility for the international space station

    International Nuclear Information System (INIS)

    McdDonald, William T.; Lewis, Johanna L.; Smith, Craig D.; DeLucas, Lawrence J.

    1997-01-01

    Directed by NASA's Office of Space Access and Technology (OSAT), the University of Alabama at Birmingham (UAB) Center for Macromolecular Crystallography (CMC) recently completed a Design Feasibility Study for the X-ray Crystallography Facility (XCF) for the International Space Station (ISS). The XCF is a facility for growing macromolecular protein crystals; harvesting, selecting, and mounting sample crystals, and snap-freezing the samples, if necessary; performing x-ray diffraction; and downlinking the diffraction data to the ground. Knowledge of the structure of protein molecules is essential for the development of pharmaceuticals by structure-based drug design techniques. Currently, x-ray diffraction of high quality protein crystals is the only method of determining the structure of these macromolecules. High quality protein crystals have been grown in microgravity onboard the Space Shuttle Orbiter for more than 10 years, but these crystals always have been returned to Earth for x-ray diffraction. The XCF will allow crystal growth, harvesting, mounting, and x-ray diffraction onboard the ISS, maximizing diffraction data quality and timeliness. This paper presents the XCF design concept, describing key feasibility issues for the ISS application and advanced technologies and operational features which resolve those issues. The conclusion is that the XCF design is feasible and can be operational onboard the ISS by early in 2002

  18. Protein energy landscapes determined by five-dimensional crystallography

    International Nuclear Information System (INIS)

    Schmidt, Marius; Srajer, Vukica; Henning, Robert; Ihee, Hyotcherl; Purwar, Namrta; Tenboer, Jason; Tripathi, Shailesh

    2013-01-01

    Barriers of activation within the photocycle of a photoactive protein were extracted from comprehensive time courses of time resolved crystallographic data collected at multiple temperature settings. Free-energy landscapes decisively determine the progress of enzymatically catalyzed reactions [Cornish-Bowden (2012 ▶), Fundamentals of Enzyme Kinetics, 4th ed.]. Time-resolved macromolecular crystallography unifies transient-state kinetics with structure determination [Moffat (2001 ▶), Chem. Rev.101, 1569–1581; Schmidt et al. (2005 ▶), Methods Mol. Biol.305, 115–154; Schmidt (2008 ▶), Ultrashort Laser Pulses in Medicine and Biology] because both can be determined from the same set of X-ray data. Here, it is demonstrated how barriers of activation can be determined solely from five-dimensional crystallography, where in addition to space and time, temperature is a variable as well [Schmidt et al. (2010 ▶), Acta Cryst. A66, 198–206]. Directly linking molecular structures with barriers of activation between them allows insight into the structural nature of the barrier to be gained. Comprehensive time series of crystallographic data at 14 different temperature settings were analyzed and the entropy and enthalpy contributions to the barriers of activation were determined. One hundred years after the discovery of X-ray scattering, these results advance X-ray structure determination to a new frontier: the determination of energy landscapes

  19. A novel inert crystal delivery medium for serial femtosecond crystallography

    Directory of Open Access Journals (Sweden)

    Chelsie E. Conrad

    2015-07-01

    Full Text Available Serial femtosecond crystallography (SFX has opened a new era in crystallography by permitting nearly damage-free, room-temperature structure determination of challenging proteins such as membrane proteins. In SFX, femtosecond X-ray free-electron laser pulses produce diffraction snapshots from nanocrystals and microcrystals delivered in a liquid jet, which leads to high protein consumption. A slow-moving stream of agarose has been developed as a new crystal delivery medium for SFX. It has low background scattering, is compatible with both soluble and membrane proteins, and can deliver the protein crystals at a wide range of temperatures down to 4°C. Using this crystal-laden agarose stream, the structure of a multi-subunit complex, phycocyanin, was solved to 2.5 Å resolution using 300 µg of microcrystals embedded into the agarose medium post-crystallization. The agarose delivery method reduces protein consumption by at least 100-fold and has the potential to be used for a diverse population of proteins, including membrane protein complexes.

  20. Smarter Drugs: How Protein Crystallography Revolutionizes Drug Design

    International Nuclear Information System (INIS)

    Smith, Clyde

    2005-01-01

    According to Smith, protein crystallography allows scientists to design drugs in a much more efficient way than the standard methods traditionally used by large drug companies, which can cost close to a billion dollars and take 10 to 15 years. 'A lot of the work can be compressed down,' Smith said. Protein crystallography enables researchers to learn the structure of molecules involved in disease and health. Seeing the loops, folds and placement of atoms in anything from a virus to a healthy cell membrane gives important information about how these things work - and how to encourage, sidestep or stop their functions. Drug design can be much faster when the relationship between structure and function tells you what area of a molecule to target. Smith will use a timeline to illustrate the traditional methods of drug development and the new ways it can be done now. 'It is very exciting work. There have been some failures, but many successes too.' A new drug to combat the flu was developed in a year or so. Smith will tell us how. He will also highlight drugs developed to combat HIV, Tuberculosis, hypertension and Anthrax.

  1. Data Management System at the Photon Factory Macromolecular Crystallography Beamline

    International Nuclear Information System (INIS)

    Yamada, Y; Matsugaki, N; Chavas, L M G; Hiraki, M; Igarashi, N; Wakatsuki, S

    2013-01-01

    Macromolecular crystallography is a very powerful tool to investigate three-dimensional structures of macromolecules at the atomic level, and is widely spread among structural biology researchers. Due to recent upgrades of the macromolecular crystallography beamlines at the Photon Factory, beamline throughput has improved, allowing more experiments to be conducted during a user's beam time. Although the number of beamlines has increased, so has the number of beam time applications. Consequently, both the experimental data from users' experiments and data derived from beamline operations have dramatically increased, causing difficulties in organizing these diverse and large amounts of data for the beamline operation staff and users. To overcome this problem, we have developed a data management system by introducing commercial middleware, which consists of a controller, database, and web servers. We have prepared several database projects using this system. Each project is dedicated to a certain aspect such as experimental results, beam time applications, beam time schedule, or beamline operation reports. Then we designed a scheme to link all the database projects.

  2. Proceedings of the Third Symposium Optical Spectroscopy SOS-84

    International Nuclear Information System (INIS)

    Fassler, D.; Feller, K.H.; Wilhelmi, B.

    1985-01-01

    The main topics of the symposium were: 1) new developments and applications of laser spectroscopy including time resolved UV/VIS spectroscopy, time resolved fluorescence spectroscopy, and laser Raman spectroscopy, 2) dynamics and photokinetics of molecular systems, and 3) spectroscopy and photoprocesses in organized biological systems

  3. Índice UV

    Science.gov (United States)

    Información general sobre el Índice UV que proporciona un pronóstico del riesgo esperado de sobreexposición a la radiación ultravioleta (UV) del sol. El índice UV va acompañado de recomendaciones para protegerse del sol.

  4. UV-visible spectroscopy as an alternative to liquid chromatography for determination of everolimus in surfactant-containing dissolution media: a useful approach based on solid-phase extraction.

    Science.gov (United States)

    Kamberi, Marika; Tran, Thu-Ngoc

    2012-11-01

    High-throughput 96-well solid phase extraction (SPE) plate with C-18 reversed phase sorbent followed by UV-visible (UV-Vis) microplate reader was applied to the analysis of hydrophobic drugs in surfactant-containing dissolution media, which are often used to evaluate the in-vitro drug release of drug eluting stents (DES). Everolimus and dissolution medium containing Triton X-405 were selected as representatives, and the appropriate SPE conditions (adsorption, washing and elution) were investigated to obtain a practical and reliable sample clean-up. It was shown that the developed SPE procedure was capable of removing interfering components (Triton X-405 and its impurities), allowing for an accurate automated spectrophotometric analysis to be performed. The proposed UV-Vis spectrophotometric method yielded equivalent results compared to a classical LC analysis method. Linear regression analysis indicated that both methods have the ability to obtain test results that are directly proportional to the concentration of analyte in the sample within the selected range of 1.0-10 μg/ml for everolimus, with a coefficient of correlation (r(2)) value of >0.998 and standard deviation of the residuals (Syx) of UV-Vis spectrophotometric method and from 98 to 102 for the HPLC method, respectively. The 95% CI of the mean recovery for the UV-Vis spectrophotometric method was 99-102% and for the HPLC method was 99-101%. No statistical difference was found between the mean recoveries of the methods (p=0.42). Hence the methods are free from interference due to Triton and other chemicals present in the dissolution medium. The variation in the amount of everolimus estimated by UV-Vis spectrophotometric and HPLC methods was ≤3.5%, and the drug release profiles obtained by both methods were found to be equivalent by evaluation with two-one-sided t-test (two-tailed, p=0.62; mean of differences, 0.17; 95% CI, 0.62-0.96) and similarity factor f2 (f2 value, 87). The excellent conformity of

  5. The 100th Anniversary of X-Ray Crystallography

    Directory of Open Access Journals (Sweden)

    Kojić-Prodić, B.

    2013-07-01

    Full Text Available The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them.W. L. BraggThe 100th anniversary of X-ray crystallography dates back to the first X-ray diffraction experiment on a crystal of copper sulphate pentahydrate. Max von Laue designed the theoretical background of the experiment, which was performed by German physicists W. Friedrich and P. Knipping in 1912. At that time, the mathematical formulation of the phenomenon and the fundamental concepts of crystallography were subjects of mineralogy. Altogether, they facilitated the development of methods for determination of the structure of matter at the atomic level. In 1913, father and son Bragg started to develop X-ray structure analysis for determination of crystal structures of simple molecules. Historic examples of structure determination starting from rock salt to complex, biologically important (macromolecules, such as globular proteins haemoglobin and myoglobin, DNA, vitamin B12 and the recent discovery of ribozyme, illustrate the development of X-ray structural analysis. The determination of 3D structures of these molecules by X-ray diffraction had opened new areas of scientific research, such as molecular biophysics, molecular genetics, structural molecular biology, bioinorganic chemistry, organometallic chemistry, and many others. The discovery and development of X-ray crystallography revolutionised our understanding of natural sciences – physics, chemistry, biology, and also science of materials. The scientific community recognised these fundamental achievements (including the discovery of X-rays by awarding twenty-eight Nobel prizes to thirty-nine men and two women. The explosive growth of science and technology in the 20th and 21st centuries had been founded on the detailed knowledge of the three-dimensional structure of molecules, which was the basis for explaining and predicting the physical, chemical, biological and

  6. High-Sensitivity Semiconductor Photocathodes for Space-Born UV Photon-Counting and Imaging, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Many UV photon-counting and imaging applications, including space-borne astronomy, missile tracking and guidance, UV spectroscopy for chemical/biological...

  7. In-vacuum long-wavelength macromolecular crystallography.

    Science.gov (United States)

    Wagner, Armin; Duman, Ramona; Henderson, Keith; Mykhaylyk, Vitaliy

    2016-03-01

    Structure solution based on the weak anomalous signal from native (protein and DNA) crystals is increasingly being attempted as part of synchrotron experiments. Maximizing the measurable anomalous signal by collecting diffraction data at longer wavelengths presents a series of technical challenges caused by the increased absorption of X-rays and larger diffraction angles. A new beamline at Diamond Light Source has been built specifically for collecting data at wavelengths beyond the capability of other synchrotron macromolecular crystallography beamlines. Here, the theoretical considerations in support of the long-wavelength beamline are outlined and the in-vacuum design of the endstation is discussed, as well as other hardware features aimed at enhancing the accuracy of the diffraction data. The first commissioning results, representing the first in-vacuum protein structure solution, demonstrate the promising potential of the beamline.

  8. X-ray powder crystallography with vertex instrumentation

    International Nuclear Information System (INIS)

    Chatzisotiriou, V.; Christofis, I.; Dimitriou, N.; Karvelas, S.; Karydas, A.G.; Loukas, D.; Pavlidis, A.; Spirou, S.; Dre, C.; Haralabidis, N.; Misiakos, K.; Tsoi, E.; Perdikatsis, V.; Psycharis, V.; Terzis, A.; Turchetta, R.

    1998-01-01

    An X-ray Diffractometer for Powder Crystallography is described along with experimental results and future plans. This is an intermediate instrument toward a long linear array system. Three channels of a silicon microstrip detector, are the detecting elements in the present instrument. Each detector channel is followed by a VLSI readout chain, which consists of a charge preamplifier with pulse shaping circuitry, a discriminator, and a 16-bit counter. Control and data acquisition is performed with a custom made PC readout card. A motorized goniometer scans the angle range of interest. Calibration of the system is done with reference samples and data which are captured with a one-channel conventional NaI detector. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  9. The monitoring system for macromolecular crystallography beamlines at BSRF

    International Nuclear Information System (INIS)

    Guo Xian; Chang Guangcai; Gan Quan; Shi Hong; Liu Peng; Sun Gongxing

    2012-01-01

    The monitoring system for macromolecular crystallography beamlines at BSRF (Beijing Synchrotron Radiation Facility) based on LabVIEW is introduced. In order to guarantee a safe, stable, and reliable running for the beamline devices, the system monitors the state of vacuum, cooling-water, optical components, beam, Liquid nitrogen in the beamlines in real time, detects faults and gives the alarm timely. System underlying uses the driver developed for the field devices for data acquisition, Data of collection is uploaded to the data-sharing platform makes it accessible via a network share. The upper system divides modules according to the actual function, and establishes the main interface of the monitoring system of beamline. To Facilitate data storage, management and inquiry, the system use LabSQL toolkit to achieve the interconnection with MySQL database which data of collection is sent to. (authors)

  10. The development of structural x-ray crystallography

    Science.gov (United States)

    Woolfson, M. M.

    2018-03-01

    From its birth in 1912, when only the simplest structures could be solved, x-ray structural crystallography is now able to solve macromolecular structures containing many thousands of independent non-hydrogen atoms. This progress has depended on, and been driven by, great technical advances in the development of powerful synchrotron x-ray sources, advanced automated equipment for the collection and storage of large data sets and powerful computers to deal with everything from data processing to running programmes employing complex algorithms for the automatic solution of structures. The sheer number of developments in the subject over the past century makes it impossible for this review to be exhaustive, but it will describe some major developments that will enable the reader to understand how the subject has grown from its humble beginnings to what it is today.

  11. Status of the digital pixel array detector for protein crystallography

    CERN Document Server

    Datte, P; Beuville, E; Endres, N; Druillole, F; Luo, L; Millaud, J E; Xuong, N H

    1999-01-01

    A two-dimensional photon counting digital pixel array detector is being designed for static and time resolved protein crystallography. The room temperature detector will significantly enhance monochromatic and polychromatic protein crystallographic through-put data rates by more than three orders of magnitude. The detector has an almost infinite photon counting dynamic range and exhibits superior spatial resolution when compared to present crystallographic phosphor imaging plates or phosphor coupled CCD detectors. The detector is a high resistivity N-type Si with a pixel pitch of 150x150 mu m, and a thickness of 300 mu m, and is bump bonded to an application specific integrated circuit. The event driven readout of the detector is based on the column architecture and allows an independent pixel hit rate above 1 million photons/s/pixel. The device provides energy discrimination and sparse data readout which yields minimal dead-time. This type of architecture allows a continuous (frameless) data acquisition, a f...

  12. A history of experimental phasing in macromolecular crystallography.

    Science.gov (United States)

    Isaacs, Neil

    2016-03-01

    It was just over a century ago that W. L. Bragg published a paper describing the first crystal structures to be determined using X-ray diffraction data. These structures were obtained from considerations of X-ray diffraction (Bragg equation), crystallography (crystal lattices and symmetry) and the scattering power of different atoms. Although W. H. Bragg proposed soon afterwards, in 1915, that the periodic electron density in crystals could be analysed using Fourier transforms, it took some decades before experimental phasing methods were developed. Many scientists contributed to this development and this paper presents the author's own perspective on this history. There will be other perspectives, so what follows is a history, rather than the history, of experimental phasing.

  13. Deep-UV high resolution cavity ring-down spectroscopy of the Schumann-Runge bands in O-16(2) and O-18(2) at wavelengths 197-203 nm

    NARCIS (Netherlands)

    Hannemann, S.; van Duijn, E.J.; Ubachs, W.M.G.

    2005-01-01

    With the use of a novel titanium:sapphire laser source delivering, upon fourth harmonic generation, narrowband and tunable radiation in the deep-UV, spectroscopic studies were performed on weak Schumann-Runge bands of oxygen. Improved values for rotational and fine structure molecular parameters for

  14. Spectral methods for study of the G-protein-coupled receptor rhodopsin: I. Vibrational and electronic spectroscopy

    Science.gov (United States)

    Struts, A. V.; Barmasov, A. V.; Brown, M. F.

    2015-05-01

    Here we review the application of modern spectral methods for the study of G-protein-coupled receptors (GPCRs) using rhodopsin as a prototype. Because X-ray analysis gives us immobile snapshots of protein conformations, it is imperative to apply spectroscopic methods for elucidating their function: vibrational (Raman, FTIR), electronic (UV-visible absorption, fluorescence) spectroscopies, and magnetic resonance (electron paramagnetic resonance, EPR), and nuclear magnetic resonance (NMR). In the first of the two companion articles, we discuss the application of optical spectroscopy for studying rhodopsin in a membrane environment. Information is obtained regarding the time-ordered sequence of events in rhodopsin activation. Isomerization of the chromophore and deprotonation of the retinal Schiff base leads to a structural change of the protein involving the motion of helices H5 and H6 in a pH-dependent process. Information is obtained that is unavailable from X-ray crystallography, which can be combined with spectroscopic studies to achieve a more complete understanding of GPCR function.

  15. Comets in UV

    Science.gov (United States)

    Shustov, B.; Sachkov, M.; Gómez de Castro, A. I.; Vallejo, J. C.; Kanev, E.; Dorofeeva, V.

    2018-04-01

    Comets are important "eyewitnesses" of Solar System formation and evolution. Important tests to determine the chemical composition and to study the physical processes in cometary nuclei and coma need data in the UV range of the electromagnetic spectrum. Comprehensive and complete studies require additional ground-based observations and in situ experiments. We briefly review observations of comets in the ultraviolet (UV) and discuss the prospects of UV observations of comets and exocomets with space-borne instruments. A special reference is made to the World Space Observatory-Ultraviolet (WSO-UV) project.

  16. Development of UV absorbing PET through Electron Irradiation

    International Nuclear Information System (INIS)

    Kim, Jung Woo; Lee, Na Eun; Lim, Hyung San; Park, Yang Jeong; Cho, Sung Oh

    2017-01-01

    Experiment to increase UV absorbance through electron beam irradiation on PET was performed. Moreover, surface hardness and roughness of each sample were observed to find the key factor increasing UV absorbance. PET sheets were irradiated with an electron beam at various fluences. The irradiated samples, as well as pristine sample, were subjected to UV-visible spectral study(UV-Vis), pencil hardness test, and scanning electron microscopy(SEM) experiment. In this study, PET samples irradiated at several conditions were analyzed through various measurements. UV absorbance-another meaning of transmittance in this study- of irradiated PET sample increased compared with pristine sample as fluence was increased in UV-Visible spectroscopy experiment.

  17. Fixed target matrix for femtosecond time-resolved and in situ serial micro-crystallography

    Directory of Open Access Journals (Sweden)

    C. Mueller

    2015-09-01

    Full Text Available We present a crystallography chip enabling in situ room temperature crystallography at microfocus synchrotron beamlines and X-ray free-electron laser (X-FEL sources. Compared to other in situ approaches, we observe extremely low background and high diffraction data quality. The chip design is robust and allows fast and efficient loading of thousands of small crystals. The ability to load a large number of protein crystals, at room temperature and with high efficiency, into prescribed positions enables high throughput automated serial crystallography with microfocus synchrotron beamlines. In addition, we demonstrate the application of this chip for femtosecond time-resolved serial crystallography at the Linac Coherent Light Source (LCLS, Menlo Park, California, USA. The chip concept enables multiple images to be acquired from each crystal, allowing differential detection of changes in diffraction intensities in order to obtain high signal-to-noise and fully exploit the time resolution capabilities of XFELs.

  18. New Paradigm for Macromolecular Crystallography Experiments at SSRL: Automated Crystal Screening And Remote Data Collection

    International Nuclear Information System (INIS)

    Soltis, S.M.; Cohen, A.E.; Deacon, A.; Eriksson, T.; Gonzalez, A.; McPhillips, S.; Chui, H.; Dunten, P.; Hollenbeck, M.; Mathews, I.; Miller, M.; Moorhead, P.; Phizackerley, R.P.; Smith, C.; Song, J.; Bedem, H. van dem; Ellis, P.; Kuhn, P.; McPhillips, T.; Sauter, N.; Sharp, K.

    2009-01-01

    Complete automation of the macromolecular crystallography experiment has been achieved at Stanford Synchrotron Radiation Lightsource (SSRL) through the combination of robust mechanized experimental hardware and a flexible control system with an intuitive user interface. These highly reliable systems have enabled crystallography experiments to be carried out from the researchers' home institutions and other remote locations while retaining complete control over even the most challenging systems. A breakthrough component of the system, the Stanford Auto-Mounter (SAM), has enabled the efficient mounting of cryocooled samples without human intervention. Taking advantage of this automation, researchers have successfully screened more than 200 000 samples to select the crystals with the best diffraction quality for data collection as well as to determine optimal crystallization and cryocooling conditions. These systems, which have been deployed on all SSRL macromolecular crystallography beamlines and several beamlines worldwide, are used by more than 80 research groups in remote locations, establishing a new paradigm for macromolecular crystallography experimentation.

  19. Synthesis of charge transfer complex of chloranilic acid as acceptor with p-nitroaniline as donor: Crystallographic, UV-visible spectrophotometric and antimicrobial studies

    Science.gov (United States)

    Zulkarnain; Khan, Ishaat M.; Ahmad, Afaq; Miyan, Lal; Ahmad, Musheer; Azizc, Nafe

    2017-08-01

    The charge transfer interaction between p-nitroaniline (PNA) and chloranilic (CAA) acid was studied spectrophotometrically in methanol at different temperatures within the range 298-328 K. This experimental work explores the nature of charge-transfer interactions that play a significant role in chemistry and biology. Structure of synthesized charge transfer (CT) complex was investigated by different technique such as X-ray crystallography, FTIR, 1HNMR, UV-visible spectroscopy, XRD and TGA-DTA, which indicates the presence of N+sbnd Hrbd2bd O- bond between donor and acceptor moieties. Spectrophotometric studies of CT complexes were carried out in methanol at different temperatures to estimate thermodynamic parameters such as formation constant (KCT), molar absorptivity (εCT), free energy change (ΔG), enthalpy change (ΔH), resonance energy (RN), oscillator strength (f), transition dipole moment (μEN) and interaction energy (ECT) were also calculated. The effect of temperatures on all the parameters was studied in methanol. 1:1 stoichiometric of CT-complex was ascertained by Benesi-Hildebrand plots giving straight line, which are good agreement with other analysis. Synthesized CT complex was screened for its antimicrobial activity such as antibacterial activity against two gram-positive bacteria, Staphylococcus aureus and bacillus subtilis and two gram negative bacteria Escherichia coli and pseudomonas aeruginosa, and antifungal activity against fungi Fusarium oxysporum, and Aspergillus flavus.

  20. UV exposure in cars.

    Science.gov (United States)

    Moehrle, Matthias; Soballa, Martin; Korn, Manfred

    2003-08-01

    There is increasing knowledge about the hazards of solar and ultraviolet (UV) radiation to humans. Although people spend a significant time in cars, data on UV exposure during traveling are lacking. The aim of this study was to obtain basic information on personal UV exposure in cars. UV transmission of car glass samples, windscreen, side and back windows and sunroof, was determined. UV exposure of passengers was evaluated in seven German middle-class cars, fitted with three different types of car windows. UV doses were measured with open or closed windows/sunroof of Mercedes-Benz E 220 T, E 320, and S 500, and in an open convertible car (Mercedes-Benz CLK). Bacillus subtilis spore film dosimeters (Viospor) were attached to the front, vertex, cheeks, upper arms, forearms and thighs of 'adult' and 'child' dummies. UV wavelengths longer than >335 nm were transmitted through car windows, and UV irradiation >380 nm was transmitted through compound glass windscreens. There was some variation in the spectral transmission of side windows according to the type of glass. On the arms, UV exposure was 3-4% of ambient radiation when the car windows were shut, and 25-31% of ambient radiation when the windows were open. In the open convertible car, the relative personal doses reached 62% of ambient radiation. The car glass types examined offer substantial protection against short-wave UV radiation. Professional drivers should keep car windows closed on sunny days to reduce occupational UV exposure. In individuals with polymorphic light eruption, produced by long-wave UVA, additional protection by plastic films, clothes or sunscreens appears necessary.

  1. Asymmetrically Substituted and π-Conjugated 2,2'-Bipyridine Derivatives: Synthesis, Spectroscopy, Computation, and Crystallography.

    Science.gov (United States)

    Bodapati, Ramakrishna; Sarma, Monima; Kanakati, Arunkumar; Das, Samar K

    2015-12-18

    A new series of monosubstituted styryl- and bistyryl-2,2'-bipyridine luminophores (compounds 16-23) have been synthesized via Horner-Wadsworth-Emmons reaction involving a monophosphonate and donor aromatic aldehydes. In the title chromophores, the amino donors are varied between acyclic and cyclic while the alkoxy donors are varied in terms of their number and position. The absorption maxima of these chromophores shift predominantly due to intramolecular charge transfer (ICT) between different donor and acceptor moieties. The title donor-acceptor molecules exhibit intense fluorescence in solution at room temperature, and their emissive behavior has been found to be highly sensitive to solvent polarity. The fluorescence spectra and quantum yields of all the chromophores were recorded in four different solvent media, and the chromophores 16, 17, 19, and 21 exhibit fluorescence in the solid state too. The influence of the nature and position of the donor functionalities in the conjugated backbone of the bipyridine moiety on the electronic absorption properties of the title chromophores (16-23) has been demonstrated, which has further been corroborated by DFT and TD-DFT computation both in gas phase and in solution phase. The crystal structure of compound 18 has been described as a representative member of the family (16-23).

  2. Interaction partners of PSD-93 studied by X-ray crystallography and fluorescence polarization spectroscopy

    DEFF Research Database (Denmark)

    Fiorentini, Monica; Bach, Anders; Strømgaard, Kristian

    2013-01-01

    PSD-93 (chapsyn-110, DLG2) is a member of the family of membrane-associated guanylate kinase (MAGUK) proteins. The MAGUK proteins are involved in receptor localization and signalling pathways. The best characterized MAGUK protein, PSD-95, is known to be involved in NMDA receptor signalling via it...

  3. UV-induced effects

    NARCIS (Netherlands)

    Liebsch, M.; Spielmann, H.; Pape, W.; Krul, C.; Deguercy, A.; Eskes, C.A.M.

    2005-01-01

    Regulatory requirements: According to the current Notes for Guidance of the Scientific Committee on Cosmetic Products and Non-Food Products (SCCNFP), cosmetic ingredients and mixtures of ingredients absorbing UV light (in particular UV filter chemicals used, for example, to ensure the light

  4. UV astronomy throughout the ages: a historical perspective

    Science.gov (United States)

    Linsky, Jeffrey L.

    2018-05-01

    Astronomers have long recognized the critical need for ultraviolet imaging, photometry and spectroscopy of stars, planets, and galaxies, but this need could not be satisfied without access to space and the development of efficient instrumentation. When UV measurements became feasible, first with rockets and then with satellites, major discoveries came rapidly. It is true in the UV spectral region as in all others, that significant increases in sensitivity, spectral resolution, and time domain coverage have led to significant new understanding of astrophysical phenomena. I will describe a selection of these discoveries made in each of three eras: (1) the early history of rocket instrumentation and Copernicus, the first UV satellite, (2) the discovery phase pioneered by the IUE, FUSE and EUVE satellites, and (3) the full flowering of UV astronomy with the successful operation of HST and its many instruments. I will also mention a few areas where future UV instrumentation could lead to new discoveries. This review concentrates on developments in stellar and interstellar UV spectroscopy; the major discoveries in galactic, extragalactic, and solar system research are beyond the scope of this review. The important topic of UV technologies and detectors, which enable the remarkable advances in UV astronomy are also not included in this review.

  5. Structure of HIV-1 protease determined by neutron crystallography

    International Nuclear Information System (INIS)

    Adachi, Motoyasu; Kuroki, Ryota

    2009-01-01

    HIV-1 protease is an aspartic protease, and plays an essential role in replication of HIV. To develop HIV-1 protease inhibitors through structure-based drug design, it is necessary to understand the catalytic mechanism and inhibitor recognition of HIV-1 protease. We have determined the crystal structure of HIV-1 protease in complex with KNI-272 to 1.9 A resolution by neutron crystallography in combination with 1.4 A resolution X-ray diffraction data. The results show that the carbonyl group of hydroxymethylcarbonyl (HMC) in KNI-272 forms a hydrogen bonding interaction with protonated Asp 25 and the hydrogen atom from the hydroxyl group of HMC forms a hydrogen bonding interaction with the deprotonated Asp125. This is the first neutron report for HIV-1/inhibitor complex and shows directly the locations of key hydrogen atoms in catalysis and in the binding of a transition-state analog. The results confirm key aspect of the presumed catalytic mechanism of HIV-1 protease and will aid in the further development of protease inhibitors. (author)

  6. Outrunning free radicals in room-temperature macromolecular crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Robin L., E-mail: robin.owen@diamond.ac.uk; Axford, Danny [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Nettleship, Joanne E.; Owens, Raymond J. [Rutherford Appleton Laboratory, Didcot OX11 0FA (United Kingdom); The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Robinson, James I.; Morgan, Ann W. [University of Leeds, Leeds LS9 7FT (United Kingdom); Doré, Andrew S. [Heptares Therapeutics Ltd, BioPark, Welwyn Garden City AL7 3AX (United Kingdom); Lebon, Guillaume; Tate, Christopher G. [MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH (United Kingdom); Fry, Elizabeth E.; Ren, Jingshan [The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Stuart, David I. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Evans, Gwyndaf [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom)

    2012-06-15

    A systematic increase in lifetime is observed in room-temperature protein and virus crystals through the use of reduced exposure times and a fast detector. A significant increase in the lifetime of room-temperature macromolecular crystals is reported through the use of a high-brilliance X-ray beam, reduced exposure times and a fast-readout detector. This is attributed to the ability to collect diffraction data before hydroxyl radicals can propagate through the crystal, fatally disrupting the lattice. Hydroxyl radicals are shown to be trapped in amorphous solutions at 100 K. The trend in crystal lifetime was observed in crystals of a soluble protein (immunoglobulin γ Fc receptor IIIa), a virus (bovine enterovirus serotype 2) and a membrane protein (human A{sub 2A} adenosine G-protein coupled receptor). The observation of a similar effect in all three systems provides clear evidence for a common optimal strategy for room-temperature data collection and will inform the design of future synchrotron beamlines and detectors for macromolecular crystallography.

  7. Outrunning free radicals in room-temperature macromolecular crystallography

    International Nuclear Information System (INIS)

    Owen, Robin L.; Axford, Danny; Nettleship, Joanne E.; Owens, Raymond J.; Robinson, James I.; Morgan, Ann W.; Doré, Andrew S.; Lebon, Guillaume; Tate, Christopher G.; Fry, Elizabeth E.; Ren, Jingshan; Stuart, David I.; Evans, Gwyndaf

    2012-01-01

    A systematic increase in lifetime is observed in room-temperature protein and virus crystals through the use of reduced exposure times and a fast detector. A significant increase in the lifetime of room-temperature macromolecular crystals is reported through the use of a high-brilliance X-ray beam, reduced exposure times and a fast-readout detector. This is attributed to the ability to collect diffraction data before hydroxyl radicals can propagate through the crystal, fatally disrupting the lattice. Hydroxyl radicals are shown to be trapped in amorphous solutions at 100 K. The trend in crystal lifetime was observed in crystals of a soluble protein (immunoglobulin γ Fc receptor IIIa), a virus (bovine enterovirus serotype 2) and a membrane protein (human A 2A adenosine G-protein coupled receptor). The observation of a similar effect in all three systems provides clear evidence for a common optimal strategy for room-temperature data collection and will inform the design of future synchrotron beamlines and detectors for macromolecular crystallography

  8. Polycapillary x-ray optics for macromolecular crystallography

    International Nuclear Information System (INIS)

    Owens, S.M.; Gibson, W.M.; Carter, D.C.; Sisk, R.C.; Ho, J.X.

    1996-01-01

    Polycapillary x-ray optics have found potential application in many different fields, including antiscatter and magnification in mammography, radiography, x-ray fluorescence, x-ray lithography, and x-ray diffraction techniques. In x-ray diffraction, an optic is used to collect divergent x-rays from a point source and redirect them into a quasi-parallel, or slightly focused beam. Monolithic polycapillary optics have been developed recently for macromolecular crystallography and have already shown considerable gains in diffracted beam intensity over pinhole collimation. Development is being pursued through a series of simulations and prototype optics. Many improvements have been made over the stage 1 prototype reported previously, which include better control over the manufacturing process, reducing the diameter of the output beam, and addition of a slight focusing at the output of the optic to further increase x-ray flux at the sample. The authors report the characteristics and performance of the stage 1 and stage 2 optics

  9. Macromolecular crystallography with a large format CMOS detector

    Energy Technology Data Exchange (ETDEWEB)

    Nix, Jay C., E-mail: jcnix@lbl.gov [Molecular Biology Consortium 12003 S. Pulaski Rd. #166 Alsip, IL 60803 U.S.A (United States)

    2016-07-27

    Recent advances in CMOS technology have allowed the production of large surface area detectors suitable for macromolecular crystallography experiments [1]. The Molecular Biology Consortium (MBC) Beamline 4.2.2 at the Advanced Light Source in Berkeley, CA, has installed a 2952 x 2820 mm RDI CMOS-8M detector with funds from NIH grant S10OD012073. The detector has a 20nsec dead pixel time and performs well with shutterless data collection strategies. The sensor obtains sharp point response and minimal optical distortion by use of a thin fiber-optic plate between the phosphor and sensor module. Shutterless data collections produce high-quality redundant datasets that can be obtained in minutes. The fine-sliced data are suitable for processing in standard crystallographic software packages (XDS, HKL2000, D*TREK, MOSFLM). Faster collection times relative to the previous CCD detector have resulted in a record number of datasets collected in a calendar year and de novo phasing experiments have resulted in publications in both Science and Nature [2,3]. The faster collections are due to a combination of the decreased overhead requirements of shutterless collections combined with exposure times that have decreased by over a factor of 2 for images with comparable signal to noise of the NOIR-1 detector. The overall increased productivity has allowed the development of new beamline capabilities and data collection strategies.

  10. Choice and maintenance of equipment for electron crystallography.

    Science.gov (United States)

    Mills, Deryck J; Vonck, Janet

    2013-01-01

    The choice of equipment for an electron crystallography laboratory will ultimately be determined by the available budget; nevertheless, the ideal lab will have two electron microscopes: a dedicated 300 kV cryo-EM with a field emission gun and a smaller LaB(6) machine for screening. The high-end machine should be equipped with photographic film or a very large CCD or CMOS camera for 2D crystal data collection; the screening microscope needs a mid-size CCD for rapid evaluation of crystal samples. The microscope room installations should provide adequate space and a special environment that puts no restrictions on the collection of high-resolution data. Equipment for specimen preparation includes a carbon coater, glow discharge unit, light microscope, plunge freezer, and liquid nitrogen containers and storage dewars. When photographic film is to be used, additional requirements are a film desiccator, dark room, optical diffractometer, and a film scanner. Having the electron microscopes and ancillary equipment well maintained and always in optimum condition facilitates the production of high-quality data.

  11. Progress in rational methods of cryoprotection in macromolecular crystallography

    International Nuclear Information System (INIS)

    Alcorn, Thomas; Juers, Douglas H.

    2010-01-01

    Measurements of the average thermal contractions (294→72 K) of 26 different cryosolutions are presented and discussed in conjunction with other recent advances in the rational design of protocols for cryogenic cooling in macromolecular crystallography. Cryogenic cooling of macromolecular crystals is commonly used for X-ray data collection both to reduce crystal damage from radiation and to gather functional information by cryogenically trapping intermediates. However, the cooling process can damage the crystals. Limiting cooling-induced crystal damage often requires cryoprotection strategies, which can involve substantial screening of solution conditions and cooling protocols. Here, recent developments directed towards rational methods for cryoprotection are described. Crystal damage is described in the context of the temperature response of the crystal as a thermodynamic system. As such, the internal and external parts of the crystal typically have different cryoprotection requirements. A key physical parameter, the thermal contraction, of 26 different cryoprotective solutions was measured between 294 and 72 K. The range of contractions was 2–13%, with the more polar cryosolutions contracting less. The potential uses of these results in the development of cryocooling conditions, as well as recent developments in determining minimum cryosolution soaking times, are discussed

  12. 1,4,8,11-Tetra[2-aryl-1-diazenyl]-1,4,8,11-tetraazacyclotetradecanes - synthesis, characterization, and x-ray crystallography of the first tetrakistriazenes to be reported

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, J.D.; Vaughan, K. [Dept. of Chemistry, Saint Mary' s Univ., Halifax, Nova Scotia (Canada)], E-mail: keith.vaughan@smu.ca; Bertolasi, V. [Dipartimento di Chimica and Centro di Strutturistica Diffrattometrica, Universita' di Ferrara, Ferrara (Italy)

    2006-10-15

    The reactions of a series of arene diazonium salts with 1,4,8,11-tetraazacyclotetradecane (cyclam) afford the novel compounds, the 1,4,8,11-tetra[2-aryl-1-diazenyl]-1,4,8,11-tetraazacyclotetradecanes (1a-1f), which are the first examples of tetrakistriazenes to be reported. The tetrakistriazenes were characterized by IR spectroscopy, proton and carbon NMR, elemental analysis, high resolution electrospray mass spectrometry, and X-ray crystallography. The analogous reaction of a diazonium salt with 1,4,7-triazacyclononane or 1,5,9-triazacyclododecane yields the tristriazenes 2, 3a, and 3b. The structures of compounds 1c and 1e were solved by X-ray crystallography at low temperature (150 K). Both molecules display a conformation where the four phenyltriazenyl groups point alternately upwards and downwards with respect to the mean macrocyclic plane. (author)

  13. 1,4,8,11-Tetra[2-aryl-1-diazenyl]-1,4,8,11-tetraazacyclotetradecanes - synthesis, characterization, and x-ray crystallography of the first tetrakistriazenes to be reported

    International Nuclear Information System (INIS)

    Clarke, J.D.; Vaughan, K.; Bertolasi, V.

    2006-01-01

    The reactions of a series of arene diazonium salts with 1,4,8,11-tetraazacyclotetradecane (cyclam) afford the novel compounds, the 1,4,8,11-tetra[2-aryl-1-diazenyl]-1,4,8,11-tetraazacyclotetradecanes (1a-1f), which are the first examples of tetrakistriazenes to be reported. The tetrakistriazenes were characterized by IR spectroscopy, proton and carbon NMR, elemental analysis, high resolution electrospray mass spectrometry, and X-ray crystallography. The analogous reaction of a diazonium salt with 1,4,7-triazacyclononane or 1,5,9-triazacyclododecane yields the tristriazenes 2, 3a, and 3b. The structures of compounds 1c and 1e were solved by X-ray crystallography at low temperature (150 K). Both molecules display a conformation where the four phenyltriazenyl groups point alternately upwards and downwards with respect to the mean macrocyclic plane. (author)

  14. Photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Shirley, D.A.

    1976-01-01

    Research activities in photoelectron spectroscopy at Lawrence Radiation Laboratory during 1976 are described. Topics covered include: the orientation of CO on Pt(III) and Ni(III) surfaces from angle-resolved photoemission; photoemission from CO on Pt(III) in the range 40 eV less than or equal to dirac constant ω less than or equal to 150 eV; photoemission studies of electron states at clean surfaces using synchrotron radiation; angle and energy dependent photoemission studies of plasmon loss structure in Al and In; d-orbital directed photoemission from copper; interpretation of angle-resolved x-ray photoemission from valence bands; atomic cross-section effects in soft x-ray photoemission from Ag, Au, and Pt valence bands; x-ray photoelectron spectroscopic studies of the electronic structure of transition metal difluorides; x-ray photoemission investigation of the density of states of B'-NiAl; the electronic structure of SrTiO 3 and some simple related oxides; fluorescence lifetime measurements of np 5 (n+1)S' states in krypton and xenon; Zeeman beats in the resonance fluorescence of the 3P 1 , states in krypton and xenon; lifetime measurements of rare-gas dimers; configuration interaction effects in the atomic photoelectron spectra of Ba, Sm, Eu, and Yb; glow discharge lamps as electron sources for electron impact excitation; electron impact excitation of electron correlation states in Ca, Sr, and Ba; photoelectron spectroscopy of atomic and molecular bismuth; relativistic effects in the uv photoelectron spectra of group VI diatomic molecules; and relative gas-phase acidities and basicities from a proton potential model

  15. Cooperativity of hydrogen-bonded networks in 7-azaindole(CH3OH)n (n=2,3) clusters evidenced by IR-UV ion-dip spectroscopy and natural bond orbital analysis.

    Science.gov (United States)

    Sakota, Kenji; Kageura, Yutaka; Sekiya, Hiroshi

    2008-08-07

    IR-UV ion-dip spectra of the 7-azaindole (7AI)(CH(3)OH)(n) (n=1-3) clusters have been measured in the hydrogen-bonded NH and OH stretching regions to investigate the stable structures of 7AI(CH(3)OH)(n) (n=1-3) in the S(0) state and the cooperativity of the H-bonding interactions in the H-bonded networks. The comparison of the IR-UV ion-dip spectra with IR spectra obtained by quantum chemistry calculations shows that 7AI(CH(3)OH)(n) (n=1-3) have cyclic H-bonded structures, where the NH group and the heteroaromatic N atom of 7AI act as the proton donor and proton acceptor, respectively. The H-bonded OH stretch fundamental of 7AI(CH(3)OH)(2) is remarkably redshifted from the corresponding fundamental of (CH(3)OH)(2) by 286 cm(-1), which is an experimental manifestation of the cooperativity in H-bonding interaction. Similarly, two localized OH fundamentals of 7AI(CH(3)OH)(3) also exhibit large redshifts. The cooperativity of 7AI(CH(3)OH)(n) (n=2,3) is successfully explained by the donor-acceptor electron delocalization interactions between the lone-pair orbital in the proton acceptor and the antibonding orbital in the proton donor in natural bond orbital (NBO) analyses.

  16. UV disinfection of water

    International Nuclear Information System (INIS)

    Skipperud, E.; Johansen; Myhrstad, J.A.

    1978-01-01

    UV radiation has been found to have advantages over chloration for the disinfection of water. New regulations for dietary conditions on Norwegian ships introduced in 1974 led to increased use of UV disinfection, and this has in the following years spread to waterworks. The present article is based on a study to determine possible limitation. The nature of the injuries to the microorganisms is first discussed, together with repair mechanisms. A table is given showing the energy required for 90 and 100 percent inactivation of a number of microorganisms. Some other factors affecting UV inactivation are briefly mentioned. (JIW)

  17. Flare activity on UV Ceti: visible and IUE observations

    International Nuclear Information System (INIS)

    Phillips, K.J.H.; Bromage, G.E.; Dufton, P.L.; Keenan, F.P.; Kingston, A.E.

    1988-01-01

    Simultaneous far-ultraviolet (IUE) spectroscopy and optical photometry and spectrophotometry of a flare on UV Ceti are reported. The flare reached ΔU=2 mag but showed only modest enhancements in the IUE spectra. The optical spectrophotometry indicated broadened Balmer line profiles during the flare, with Hβ and Hγ clearly showing red wings (∼ 100 km s -1 ). The results are compared with other IUE and optical observations of UV Ceti, and their solar analogues. (author)

  18. Flare activity on UV CETI: visible and IUE observations

    International Nuclear Information System (INIS)

    Phillips, K.J.H.; Bromage, G.E.; Dufton, P.L.; Keenan, F.P.; Kingston, A.E.

    1988-06-01

    Simultaneous far-ultraviolet (IUE) spectroscopy and optical photometry and spectrophotometry of a flare on UV Ceti are reported. The flare reached ΔU = 2sup(m) but showed only modest enhancements in the IUE spectra. The optical spectrophotometry indicated broadened Balmer line profiles during the flare, with Hβ and Hγ clearly showing red wings. The results are compared with other IUE and optical observations of UV Ceti, and their solar analogues. (author)

  19. Comparing pharmacophore models derived from crystallography and NMR ensembles

    Science.gov (United States)

    Ghanakota, Phani; Carlson, Heather A.

    2017-11-01

    NMR and X-ray crystallography are the two most widely used methods for determining protein structures. Our previous study examining NMR versus X-Ray sources of protein conformations showed improved performance with NMR structures when used in our Multiple Protein Structures (MPS) method for receptor-based pharmacophores (Damm, Carlson, J Am Chem Soc 129:8225-8235, 2007). However, that work was based on a single test case, HIV-1 protease, because of the rich data available for that system. New data for more systems are available now, which calls for further examination of the effect of different sources of protein conformations. The MPS technique was applied to Growth factor receptor bound protein 2 (Grb2), Src SH2 homology domain (Src-SH2), FK506-binding protein 1A (FKBP12), and Peroxisome proliferator-activated receptor-γ (PPAR-γ). Pharmacophore models from both crystal and NMR ensembles were able to discriminate between high-affinity, low-affinity, and decoy molecules. As we found in our original study, NMR models showed optimal performance when all elements were used. The crystal models had more pharmacophore elements compared to their NMR counterparts. The crystal-based models exhibited optimum performance only when pharmacophore elements were dropped. This supports our assertion that the higher flexibility in NMR ensembles helps focus the models on the most essential interactions with the protein. Our studies suggest that the "extra" pharmacophore elements seen at the periphery in X-ray models arise as a result of decreased protein flexibility and make very little contribution to model performance.

  20. Radiation damage to nucleoprotein complexes in macromolecular crystallography

    International Nuclear Information System (INIS)

    Bury, Charles; Garman, Elspeth F.; Ginn, Helen Mary; Ravelli, Raimond B. G.; Carmichael, Ian; Kneale, Geoff; McGeehan, John E.

    2015-01-01

    Quantitative X-ray induced radiation damage studies employing a model protein–DNA complex revealed a striking partition of damage sites. The DNA component was observed to be far more resistant to specific damage compared with the protein. Significant progress has been made in macromolecular crystallography over recent years in both the understanding and mitigation of X-ray induced radiation damage when collecting diffraction data from crystalline proteins. In contrast, despite the large field that is productively engaged in the study of radiation chemistry of nucleic acids, particularly of DNA, there are currently very few X-ray crystallographic studies on radiation damage mechanisms in nucleic acids. Quantitative comparison of damage to protein and DNA crystals separately is challenging, but many of the issues are circumvented by studying pre-formed biological nucleoprotein complexes where direct comparison of each component can be made under the same controlled conditions. Here a model protein–DNA complex C.Esp1396I is employed to investigate specific damage mechanisms for protein and DNA in a biologically relevant complex over a large dose range (2.07–44.63 MGy). In order to allow a quantitative analysis of radiation damage sites from a complex series of macromolecular diffraction data, a computational method has been developed that is generally applicable to the field. Typical specific damage was observed for both the protein on particular amino acids and for the DNA on, for example, the cleavage of base-sugar N 1 —C and sugar-phosphate C—O bonds. Strikingly the DNA component was determined to be far more resistant to specific damage than the protein for the investigated dose range. At low doses the protein was observed to be susceptible to radiation damage while the DNA was far more resistant, damage only being observed at significantly higher doses

  1. Room-temperature macromolecular serial crystallography using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Francesco Stellato

    2014-07-01

    Full Text Available A new approach for collecting data from many hundreds of thousands of microcrystals using X-ray pulses from a free-electron laser has recently been developed. Referred to as serial crystallography, diffraction patterns are recorded at a constant rate as a suspension of protein crystals flows across the path of an X-ray beam. Events that by chance contain single-crystal diffraction patterns are retained, then indexed and merged to form a three-dimensional set of reflection intensities for structure determination. This approach relies upon several innovations: an intense X-ray beam; a fast detector system; a means to rapidly flow a suspension of crystals across the X-ray beam; and the computational infrastructure to process the large volume of data. Originally conceived for radiation-damage-free measurements with ultrafast X-ray pulses, the same methods can be employed with synchrotron radiation. As in powder diffraction, the averaging of thousands of observations per Bragg peak may improve the ratio of signal to noise of low-dose exposures. Here, it is shown that this paradigm can be implemented for room-temperature data collection using synchrotron radiation and exposure times of less than 3 ms. Using lysozyme microcrystals as a model system, over 40 000 single-crystal diffraction patterns were obtained and merged to produce a structural model that could be refined to 2.1 Å resolution. The resulting electron density is in excellent agreement with that obtained using standard X-ray data collection techniques. With further improvements the method is well suited for even shorter exposures at future and upgraded synchrotron radiation facilities that may deliver beams with 1000 times higher brightness than they currently produce.

  2. Influence of solvents on UV degradation of polysilanes films

    International Nuclear Information System (INIS)

    Tkacova, M.; Schauer, F.

    2014-01-01

    In the paper we deal with the UV degradation process in polymers in general and silicon based polymers in particular, using the well-known prototypical polymer poly[methylphenylsilylene] (PMPSi). Attention is focused on the influence of solvents used for films preparation an don the UV degradation process in these films examined by Photoluminescence (PL) spectroscopy and Electrochemical Impedance Spectroscopy (EIS). The goal of the study is oriented on the writing of information into thin polymer films and production of nano masks for semiconductor industry. PMPSi is a prototypical silicon-based polymer from the polysilanes (PS) group that attracted attention because of their nonlinear optical and photoelectrical properties (authors)

  3. Gamma Spectroscopy

    NARCIS (Netherlands)

    Niemantsverdriet, J.W.; Butz, Tilman; Ertl, G.; Knözinger, H.; Schüth, F.

    2008-01-01

    No abstract. The sections in this article are 1 Introduction 2 Mössbauer Spectroscopy 3 Time-Differential Perturbed Angular Correlations (TDPAC) 4 Conclusions and Outlook Keywords: Mössbauer spectroscopy; gamma spectroscopy; perturbed angular correlation; TDPAC

  4. The protein micro-crystallography beamlines for targeted protein research program

    International Nuclear Information System (INIS)

    Hirata, Kunio; Yamamoto, Masaki; Matsugaki, Naohiro; Wakatsuki, Soichi

    2010-01-01

    In order to collect proper diffraction data from outstanding micro-crystals, a brand-new data collection system should be designed to provide high signal-to noise ratio in diffraction images. SPring-8 and KEK-PF are currently developing two micro-beam beamlines for Targeted Proteins Research Program by MEXT of Japan. The program aims to reveal the structure and function of proteins that are difficult to solve but have great importance in both academic research and industrial application. At SPring-8, a new 1-micron beam beamline for protein micro-crystallography, RIKEN Targeted Proteins Beamline (BL32XU), is developed. At KEK-PF a new low energy micro-beam beamline, BL-1A, is dedicated for SAD micro-crystallography. The two beamlines will start operation in the end of 2010. The present status of the research and development for protein micro-crystallography will be presented. (author)

  5. Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

    International Nuclear Information System (INIS)

    Zvezdanovic, Jelena; Cvetic, Tijana; Veljovic-Jovanovic, Sonja; Markovic, Dejan

    2009-01-01

    Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching

  6. Towards a compact and precise sample holder for macromolecular crystallography.

    Science.gov (United States)

    Papp, Gergely; Rossi, Christopher; Janocha, Robert; Sorez, Clement; Lopez-Marrero, Marcos; Astruc, Anthony; McCarthy, Andrew; Belrhali, Hassan; Bowler, Matthew W; Cipriani, Florent

    2017-10-01

    Most of the sample holders currently used in macromolecular crystallography offer limited storage density and poor initial crystal-positioning precision upon mounting on a goniometer. This has now become a limiting factor at high-throughput beamlines, where data collection can be performed in a matter of seconds. Furthermore, this lack of precision limits the potential benefits emerging from automated harvesting systems that could provide crystal-position information which would further enhance alignment at beamlines. This situation provided the motivation for the development of a compact and precise sample holder with corresponding pucks, handling tools and robotic transfer protocols. The development process included four main phases: design, prototype manufacture, testing with a robotic sample changer and validation under real conditions on a beamline. Two sample-holder designs are proposed: NewPin and miniSPINE. They share the same robot gripper and allow the storage of 36 sample holders in uni-puck footprint-style pucks, which represents 252 samples in a dry-shipping dewar commonly used in the field. The pucks are identified with human- and machine-readable codes, as well as with radio-frequency identification (RFID) tags. NewPin offers a crystal-repositioning precision of up to 10 µm but requires a specific goniometer socket. The storage density could reach 64 samples using a special puck designed for fully robotic handling. miniSPINE is less precise but uses a goniometer mount compatible with the current SPINE standard. miniSPINE is proposed for the first implementation of the new standard, since it is easier to integrate at beamlines. An upgraded version of the SPINE sample holder with a corresponding puck named SPINEplus is also proposed in order to offer a homogenous and interoperable system. The project involved several European synchrotrons and industrial companies in the fields of consumables and sample-changer robotics. Manual handling of mini

  7. Super-resolution biomolecular crystallography with low-resolution data.

    Science.gov (United States)

    Schröder, Gunnar F; Levitt, Michael; Brunger, Axel T

    2010-04-22

    -ray crystallography and cryo-electron microscopy: as optical imaging advances to subnanometre resolution, it can use similar tools.

  8. From crystallography to structural biology, a century of discoveries

    Directory of Open Access Journals (Sweden)

    Montoya, Guillermo

    2015-04-01

    Full Text Available From crystallography, the technique mostly used to study the structure of matter, the field mutated into structural biology, has mutated in life sciences into structural biology, which has been developed as an essential and rather successful area of research to fully understand the workings of cellular pathways. The application of physical approaches to biological systems has been crucial to comprehend the structure and function of the biological components of living organisms. In this assay the author walks the reader through the last century, which has witnessed how this life sciences research area was born and moved towards larger assemblies in the core of crucial biological problems. The influence of research in physics, biochemistry and molecular biology has been key in the successes and large body of seminal results obtained by structural biologists. The author proposes that the future of this area implies the integration of its results at the cellular level apart of using more quantitative approaches to describe biological processes.La cristalografía, la técnica más ampliamente usada para estudiar la estructura de la materia, ha evolucionado en las ciencias de la vida hacia la biología estructural, una exitosa área de investigación encaminada a comprender el funcionamiento de los procesos celulares. La aplicación de aproximaciones físicas a sistemas biológicos es clave para entender la estructura y funcionamiento de los componentes de los organismos. En este artículo el autor ofrece al lector un paseo por la evolución de esta área de conocimiento durante el siglo XX, desde su nacimiento hasta el análisis de grandes complejos macromoleculares, protagonistas importantes en diversos procesos biológicos. La influencia de investigaciones en física, bioquímica y biología molecular ha sido clave para los numerosos éxitos alcanzados por biólogos estructurales. El autor sostiene que el futuro de esta disciplina pasa por la

  9. Towards a semiquantitative non invasive characterisation of Tyrian purple dye composition: Convergence of UV-Visible reflectance spectroscopy and fast-high temperature-high performance liquid chromatography with photodiode array detection.

    Science.gov (United States)

    Clementi, Catia; Nowik, Witold; Romani, Aldo; Cardon, Dominique; Trojanowicz, Marek; Davantès, Athénaïs; Chaminade, Pierre

    2016-07-05

    In this paper, partial least square (PLS) regression is innovatively applied for a semi-quantitative non invasive study of the most precious dye of Antiquity: Tyrian purple. This original approach for the study of organic dyes in the cultural heritage field, is based on the correlation of spectrophotometric (UV-Visible) and chromatographic (Fast-HT-HPLC-PDA) data from an extensive set of textiles prepared with different snail species according to historical recipes. A cross-validated PLS model, based on the quantity of 6,6'-dibromoindigotin, displays an excellent correlation factor (R(2)Y = 0.987) between values determined by chromatography and those predicted from reflectance spectra. This indicates that the spectral features of Tyrian purple on textile fibre is strictly related to the amount of this indigoid component whose content may be non invasively predicted from reflectance spectrum. The studied correlation also highlights that, independently of the dyeing method and nature of the textile fibre used, the relative content of 6,6'-dibromindigotin may be used as a parameter to distinguish samples prepared with Hexaplex trunculus L. snails from those prepared with further mollusc species. To validate this model, archaeological textile fragments dating from the Roman period were successfully examined. The results achieved open an absolutely new way in Tyrian purple analysis in cultural heritage by non invasive spectroscopic techniques attesting their convergence with HPLC and giving them a semi-quantitative value. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. The Joint Structural Biology Group beam lines at the ESRF: Modern macromolecular crystallography

    CERN Document Server

    Mitchell, E P

    2001-01-01

    Macromolecular crystallography has evolved considerably over the last decade. Data sets in under an hour are now possible on high throughput beam lines leading to electron density and, possibly, initial models calculated on-site. There are five beam lines currently dedicated to macromolecular crystallography: the ID14 complex and BM-14 (soon to be superseded by ID-29). These lines handle over five hundred projects every six months and demand is increasing. Automated sample handling, alignment and data management protocols will be required to work efficiently with this demanding load. Projects developing these themes are underway within the JSBG.

  11. Remote Access to the PXRR Macromolecular Crystallography Facilities at the NSLS

    Energy Technology Data Exchange (ETDEWEB)

    A Soares; D Schneider; J Skinner; M Cowan; R Buono; H Robinson; A Heroux; M Carlucci-Dayton; A Saxena; R Sweet

    2011-12-31

    The most recent surge of innovations that have simplified and streamlined the process of determining macromolecular structures by crystallography owes much to the efforts of the structural genomics community. However, this was only the last step in a long evolution that saw the metamorphosis of crystallography from an heroic effort that involved years of dedication and skill into a straightforward measurement that is occasionally almost trivial. Many of the steps in this remarkable odyssey involved reducing the physical labor that is demanded of experimenters in the field. Other steps reduced the technical expertise required for conducting those experiments.

  12. A Maltose-Binding Protein Fusion Construct Yields a Robust Crystallography Platform for MCL1.

    Directory of Open Access Journals (Sweden)

    Matthew C Clifton

    Full Text Available Crystallization of a maltose-binding protein MCL1 fusion has yielded a robust crystallography platform that generated the first apo MCL1 crystal structure, as well as five ligand-bound structures. The ability to obtain fragment-bound structures advances structure-based drug design efforts that, despite considerable effort, had previously been intractable by crystallography. In the ligand-independent crystal form we identify inhibitor binding modes not observed in earlier crystallographic systems. This MBP-MCL1 construct dramatically improves the structural understanding of well-validated MCL1 ligands, and will likely catalyze the structure-based optimization of high affinity MCL1 inhibitors.

  13. A pixel detector for the protein crystallography beamline at the SLS

    CERN Document Server

    Brönnimann, C; Eikenberry, E F; Fischer, P; Florin, S; Horisberger, R P; Lindner, Manfred; Schmitt, B; Schulze, C

    2002-01-01

    At the Paul Scherrer Institute a new synchrotron light source is currently under construction, the Swiss Light Source (SLS), which will be operational in summer 2001. Among the first beamlines is a high brightness, micro-focusing protein crystallography beamline. It will be equipped with a pixel detector, which has several features of interest for the next generation of protein crystallography detectors. The point spread function and the effect of charge sharing was measured with a prototype detector in a test experiment at the European Synchrotron Radiation Facility in Grenoble. The concepts of the SLS pixel detector is presented as well as test results from radiation hard prototype chips.

  14. Remote Access to the PXRR Macromolecular Crystallography Facilities at the NSLS

    International Nuclear Information System (INIS)

    Soares, A.; Schneider, D.; Skinner, J.; Cowan, M.; Buono, R.; Robinson, H.; Heroux, A.; Carlucci-Dayton, M.; Saxena, A.; Sweet, R.

    2008-01-01

    The most recent surge of innovations that have simplified and streamlined the process of determining macromolecular structures by crystallography owes much to the efforts of the structural genomics community. However, this was only the last step in a long evolution that saw the metamorphosis of crystallography from an heroic effort that involved years of dedication and skill into a straightforward measurement that is occasionally almost trivial. Many of the steps in this remarkable odyssey involved reducing the physical labor that is demanded of experimenters in the field. Other steps reduced the technical expertise required for conducting those experiments.

  15. High Resolution Spectroscopy in the Divertor and Edge Regions of Alcator-C Mode and Measurement of Radiative Transfer in Vacuum-UV Line Emission from Magnetic Fusion Devices

    International Nuclear Information System (INIS)

    Griem, Hans R.

    2005-01-01

    Spectroscopic diagnostics were carried out both at MIT and at the University of Maryland. At MIT, measurements were made of toroidal flow velocities in the mid-plane of the inner and outer scrape-off layers (SOL) of Alcator C-Mod plasmas, using a high-resolution spectrograph. Subsequently, the MIT/Alcator procedures based upon visible spectroscopy were transferred to the new Maryland centrifugal experiment (MCX). In a further effort towards data refinement, we expanded the hydrogen measurements from the n approaches to 2 Balmer series in the visible to the n approaches to 1 Lyman series in the vacuum-ultraviolet (vuv) spectral region. Recent results were presented at APS Division of Plasma Physics meetings and published in Physics of Plasmas in 2004 and 2005. Further details can be found in the annual progress reports to the Department of Energy

  16. Predicting Key Agronomic Soil Properties with UV-Vis Fluorescence Measurements Combined with Vis-NIR-SWIR Reflectance Spectroscopy: A Farm-Scale Study in a Mediterranean Viticultural Agroecosystem.

    Science.gov (United States)

    Vaudour, Emmanuelle; Cerovic, Zoran G; Ebengo, Dav M; Latouche, Gwendal

    2018-04-10

    For adequate crop and soil management, rapid and accurate techniques for monitoring soil properties are particularly important when a farmer starts up his activities and needs a diagnosis of his cultivated fields. This study aimed to evaluate the potential of fluorescence measured directly on 146 whole soil solid samples, for predicting key soil properties at the scale of a 6 ha Mediterranean wine estate with contrasting soils. UV-Vis fluorescence measurements were carried out in conjunction with reflectance measurements in the Vis-NIR-SWIR range. Combining PLSR predictions from Vis-NIR-SWIR reflectance spectra and from a set of fluorescence signals enabled us to improve the power of prediction of a number of key agronomic soil properties including SOC, N tot , CaCO₃, iron, fine particle-sizes (clay, fine silt, fine sand), CEC, pH and exchangeable Ca 2+ with cross-validation RPD ≥ 2 and R² ≥ 0.75, while exchangeable K⁺, Na⁺, Mg 2+ , coarse silt and coarse sand contents were fairly predicted (1.42 ≤ RPD < 2 and 0.54 ≤ R² < 0.75). Predictions of SOC, N tot , CaCO₃, iron contents, and pH were still good (RPD ≥ 1.8, R² ≥ 0.68) when using a single fluorescence signal or index such as SFR_R or FERARI, highlighting the unexpected importance of red excitations and indices derived from plant studies. The predictive ability of single fluorescence indices or original signals was very significant for topsoil: this is very important for a farmer who wishes to update information on soil nutrient for the purpose of fertility diagnosis and particularly nitrogen fertilization. These results open encouraging perspectives for using miniaturized fluorescence devices enabling red excitation coupled with red or far-red fluorescence emissions directly in the field.

  17. Predicting Key Agronomic Soil Properties with UV-Vis Fluorescence Measurements Combined with Vis-NIR-SWIR Reflectance Spectroscopy: A Farm-Scale Study in a Mediterranean Viticultural Agroecosystem

    Directory of Open Access Journals (Sweden)

    Emmanuelle Vaudour

    2018-04-01

    Full Text Available For adequate crop and soil management, rapid and accurate techniques for monitoring soil properties are particularly important when a farmer starts up his activities and needs a diagnosis of his cultivated fields. This study aimed to evaluate the potential of fluorescence measured directly on 146 whole soil solid samples, for predicting key soil properties at the scale of a 6 ha Mediterranean wine estate with contrasting soils. UV-Vis fluorescence measurements were carried out in conjunction with reflectance measurements in the Vis-NIR-SWIR range. Combining PLSR predictions from Vis-NIR-SWIR reflectance spectra and from a set of fluorescence signals enabled us to improve the power of prediction of a number of key agronomic soil properties including SOC, Ntot, CaCO3, iron, fine particle-sizes (clay, fine silt, fine sand, CEC, pH and exchangeable Ca2+ with cross-validation RPD ≥ 2 and R² ≥ 0.75, while exchangeable K+, Na+, Mg2+, coarse silt and coarse sand contents were fairly predicted (1.42 ≤ RPD < 2 and 0.54 ≤ R² < 0.75. Predictions of SOC, Ntot, CaCO3, iron contents, and pH were still good (RPD ≥ 1.8, R² ≥ 0.68 when using a single fluorescence signal or index such as SFR_R or FERARI, highlighting the unexpected importance of red excitations and indices derived from plant studies. The predictive ability of single fluorescence indices or original signals was very significant for topsoil: this is very important for a farmer who wishes to update information on soil nutrient for the purpose of fertility diagnosis and particularly nitrogen fertilization. These results open encouraging perspectives for using miniaturized fluorescence devices enabling red excitation coupled with red or far-red fluorescence emissions directly in the field.

  18. EarthFinder: A Precise Radial Velocity Survey Probe Mission of our Nearest Stellar Neighbors for Earth-Mass Habitable Zone Analogs Using High-Resolution UV-Vis-NIR Echelle Spectroscopy on a Space Platform

    Science.gov (United States)

    Plavchan, Peter; EarthFinder Team

    2018-01-01

    We are investigating the science case for a 1.0-1.4 meter space telescope to survey the closest, brightest FGKM main sequence stars to search for Habitable Zone (HZ) Earth analogs using the precise radial velocity (PRV) technique at a precision of 1-10 cm/s. Our baseline instrument concept uses two diffraction-limited spectrographs operating in the 0.4-1.0 microns and 1.0-2.4 microns spectral regions each with a spectral resolution of R=150,000~200,000, with the possibility of a third UV arm. Because the instrument utilizes a diffraction-limited input beam, the spectrograph would be extremely compact, less than 50 cm on a side, and illumination can be stabilized with the coupling of starlight into single mode fibers. With two octaves of wavelength coverage and a cadence unimpeded by any diurnal, seasonal, and atmospheric effects, EarthFinder will offer a unique platform for recovering stellar activity signals from starspots, plages, granulation, etc. to detect exoplanets at velocity semi-amplitudes currently not obtainable from the ground. Variable telluric absorption and emission lines may potentially preclude achieving PRV measurements at or below 10 cm/s in the visible and advantage compared to an annual ~3-6 month observing season from the ground for mitigating stellar activity and detecting the orbital periods of HZ Earth-mass analogs (e.g. ~6-months to ~2 years). Finally, we are compiling a list of ancillary science cases for the observatory, ranging from asteroseismology to the direct measurement of the expansion of the Universe.

  19. UV Deprivation Influences Social UV Preference in Juvenile Sticklebacks

    Directory of Open Access Journals (Sweden)

    Ricarda Modarressie

    2015-05-01

    Full Text Available Social aggregations occur in many different animal taxa and mainly result from non-random assortment. Investigating factors that shape and maintain the composition of social aggregations are among others a main topic for understanding ecological speciation processes. Aggregation decisions are mediated by olfactory and visual cues, which in many animals are extended into the UV part of the electromagnetic spectrum. Here, we were interested in developmental plasticity of social preferences with respect to UV radiation in aquatic organisms. Specifically, we tested whether different lighting environments with respect to UV wavelengths during early life stages influence the shoaling preference in juvenile threespine sticklebacks (Gasterosteus aculeatus. Family (full-sibling groups were split and reared under UV-lacking (UV- and UV-present (UV+ lighting conditions. Subsequent shoal choice experiments, in which test fish from both rearing conditions could simultaneously choose between a shoal seen behind a UV-blocking (UV- and a shoal seen behind a UV-transmitting (UV+ filter, revealed a significant effect of lighting condition during rearing on association preference. Test fish that had been deprived of UV spent significantly more time near the UV- shoal compared to the test fish reared under full-spectrum lighting conditions. The results are discussed with respect to plasticity of the visual system and environmental lighting conditions.

  20. A complete vibrational study on a potential environmental toxicant agent, the 3,3',4,4'-tetrachloroazobenzene combining the FTIR, FTRaman, UV-Visible and NMR spectroscopies with DFT calculations.

    Science.gov (United States)

    Castillo, María V; Pergomet, Jorgelina L; Carnavale, Gustavo A; Davies, Lilian; Zinczuk, Juan; Brandán, Silvia A

    2015-01-05

    In this study 3,3',4,4'-tetrachloroazobenzene (TCAB) was prepared and then characterized by infrared, Raman, multidimensional nuclear magnetic resonance (NMR) and ultraviolet-visible spectroscopies. The density functional theory (DFT) together with the 6-31G(*) and 6-311++G(**) basis sets were used to study the structures and vibrational properties of the two cis and trans isomers of TCAB. The harmonic vibrational wavenumbers for the optimized geometries were calculated at the same theory levels. A complete assignment of all the observed bands in the vibrational spectra of TCAB was performed combining the DFT calculations with the scaled quantum mechanical force field (SQMFF) methodology. The molecular electrostatic potentials, atomic charges, bond orders and frontier orbitals for the two isomers of TCAB were compared and analyzed. The comparison of the theoretical ultraviolet-visible spectrum with the corresponding experimental demonstrates a good concordance while the calculated (1)H and (13)C chemicals shifts are in good conformity with the corresponding experimental NMR spectra of TCAB in solution. The npp(*) transitions for both forms were studied by natural bond orbital (NBO) while the topological properties were calculated by employing Bader's Atoms in the Molecules (AIM) theory. This study shows that the cis and trans isomers exhibit different structural and vibrational properties and absorption bands. Copyright © 2014. Published by Elsevier B.V.