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Sample records for absorption spectroscopic analyses

  1. Ultraviolet-Absorption Spectroscopic Biofilm Monitor

    NASA Technical Reports Server (NTRS)

    Micheels, Ronald H.

    2004-01-01

    An ultraviolet-absorption spectrometer system has been developed as a prototype instrument to be used in continuous, real-time monitoring to detect the growth of biofilms. Such monitoring is desirable because biofilms are often harmful. For example, biofilms in potable-water and hydroponic systems act as both sources of pathogenic bacteria that resist biocides and as a mechanism for deterioration (including corrosion) of pipes. Biofilms formed from several types of hazardous bacteria can thrive in both plant-growth solutions and low-nutrient media like distilled water. Biofilms can also form in condensate tanks in air-conditioning systems and in industrial heat exchangers. At present, bacteria in potable-water and plant-growth systems aboard the space shuttle (and previously on the Mir space station) are monitored by culture-plate counting, which entails an incubation period of 24 to 48 hours for each sample. At present, there are no commercially available instruments for continuous monitoring of biofilms in terrestrial or spaceborne settings.

  2. Martian dunite NWA 2737: Integrated spectroscopic analyses of brown olivine

    NASA Astrophysics Data System (ADS)

    Pieters, Carle M.; Klima, Rachel L.; Hiroi, Takahiro; Dyar, M. Darby; Lane, Melissa D.; Treiman, Allan H.; Noble, Sarah K.; Sunshine, Jessica M.; Bishop, Janice L.

    2008-06-01

    A second Martian meteorite has been identified that is composed primarily of heavily shocked dunite, Northwest Africa (NWA) 2737. This meteorite has several similarities to the Chassigny dunite cumulate, but the olivine is more Mg rich and, most notably, is very dark and visually brown. Carefully coordinated analyses of NWA 2737 whole-rock and olivine separates were undertaken using visible and near-infrared reflectance, midinfrared emission and reflectance, and Mössbauer spectroscopic studies of the same samples along with detailed petrography, chemistry, scanning electron microscopy, and transmission electron microscopy analyses. Midinfrared spectra of this sample indicate that the olivine is fully crystalline and that its molecular structure remains intact. The unusual color and spectral properties that extend from the visible through the near-infrared part of the spectrum are shown to be due to nanophase metallic iron particles dispersed throughout the olivine during a major shock event on Mars. Although a minor amount of Fe3+ is present, it cannot account for the well-documented unusual optical properties of Martian meteorite NWA 2737. Perhaps unique to the Martian environment, this ``brown'' olivine exhibits spectral properties that can potentially be used to remotely explore the pressure-temperature history of surface geology as well as assess surface composition.

  3. Absorption and emission spectroscopic characterisation of 8-amino-riboflavin

    NASA Astrophysics Data System (ADS)

    Tyagi, A.; Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.; Mack, M.; Ghisla, S.

    2009-10-01

    The flavin dye 8-amino-8-demethyl- D-riboflavin (AF) in the solvents water, DMSO, methanol, and chloroform/DMSO was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin). The fluorescence quantum yield of AF in the studied solvents varies between 20% and 50%. The fluorescence lifetimes were found to be in the 2-5 ns range. AF is well soluble in DMSO, weakly soluble in water and methanol, and practically insoluble in chloroform. The limited solubility causes AF aggregation, which was seen in differences between measured absorption spectra and fluorescence excitation spectra. Light scattering in the dye absorption region is discussed and approximate absorption cross-section spectra are determined from the combined measurement of transmission and fluorescence excitation spectra. The photo-stability of AF was studied by prolonged light exposure. The photo-degradation routes of AF are discussed.

  4. Chemical and spectroscopic analyses of organic matter transformation in warming tundra soils

    NASA Astrophysics Data System (ADS)

    Herndon, E.; Roy Chowdhury, T.; Mann, B. F.; Graham, D. E.; Bargar, J.; Gu, B.; Liang, L.

    2013-12-01

    Many tundra soils are currently major carbon sinks; however, an increase in temperature may shift these systems to C sources and create a positive feedback for warming. In order to predict future C release from tundra soils, it is necessary to quantify rates of SOM degradation and to identify the reactants and products of microbial decomposition reactions. In this study, multiple spectroscopic techniques are used to investigate SOM during laboratory incubations of tundra soils. We aim to characterize the chemical transformation of organic matter during decomposition as a function of temperature and geochemistry. Frozen soil cores were obtained from the Barrow Environmental Observatory (BEO) in northern Alaska as part of the Next Generation Ecosystem Experiment Arctic project. To investigate the influence of temperature on organic matter degradation and compositional changes, soil horizons from each core were homogenized and soil material was incubated at -2°C, +4°C, or +8°C. Samples were sacrificed periodically over 100 days, and chemical and physical extractions were used to separate SOM into operationally-defined pools, including light (density < 1.6 g cm-2) and mineral-bound, and water-, acid-, base-, and non-soluble fractions. A suite of wet-chemical and spectroscopic analyses was used to measure CO2 and CH4 formation and soil C compositional changes, including techniques such as Fourier transform infrared spectroscopy, high performance liquid chromatography (HPLC), high resolution mass spectrometry, and X-ray absorption spectroscopy. Detailed chemical and spectroscopic analyses reveal significant differences amongst extracts and with depth in the soil. In general, more organic C was extracted in the base than in the acid and water fractions, and mineral-bound organic C increased with depth. The water-soluble C fraction showed the lowest molar absorptivity of the three extracts and consisted of mostly lower-molecular weight organics. Acid-soluble C increased

  5. Three-dimensional spherical analyses of cosmological spectroscopic surveys

    NASA Astrophysics Data System (ADS)

    Nicola, Andrina; Refregier, Alexandre; Amara, Adam; Paranjape, Aseem

    2014-09-01

    Spectroscopic redshift surveys offer great prospects for constraining the dark sector in cosmology. Future surveys will however be both deep and wide and will thus require an analysis in three-dimensional spherical geometry. We review and compare several methods which have been proposed in the literature for this purpose, focusing in particular on implementations of the spherical harmonic tomography (SHT) power spectrum Clij and the spherical Fourier Bessel (SFB) power spectrum Cl(k ,k'). Using a Fisher analysis, we compare the forecasted constraints on cosmological parameters using these statistics. These constraints typically rely on approximations such as the Limber approximation and make specific choices in the numerical implementation of each statistic. Using a series of toy models, we explore the applicability of these approximations and study the sensitivity of the SHT and SFB statistics to the details of their implementation. In particular, we show that overlapping redshift bins may improve cosmological constraints using the SHT statistic when the number of bins is small, and that the SFB constraints are quite robust to changes in the assumed distance-redshift relation. We also find that the SHT can be tailored to be more sensitive to modes at redshifts close to the survey boundary, while the SFB appears better suited to capture information beyond the smooth shape of the power spectrum. In this context, we discuss the pros and cons of the different techniques and their impact on the design and analysis of future wide field spectroscopic surveys.

  6. Spectroscopic study of low-temperature hydrogen absorption in palladium

    SciTech Connect

    Ienaga, K. Takata, H.; Onishi, Y.; Inagaki, Y.; Kawae, T.; Tsujii, H.; Kimura, T.

    2015-01-12

    We report real-time detection of hydrogen (H) absorption in metallic palladium (Pd) nano-contacts immersed in liquid H{sub 2} using inelastic electron spectroscopy (IES). After introduction of liquid H{sub 2}, the spectra exhibit the time evolution from the pure Pd to the Pd hydride, indicating that H atoms are absorbed in Pd nano-contacts even at the temperature where the thermal process is not expected. The IES time and bias voltage dependences show that H absorption develops by applying bias voltage 30 ∼ 50 mV, which can be explained by quantum tunneling. The results represent that IES is a powerful method to study the kinetics of high density H on solid surface.

  7. Photoelectron, nuclear gamma-ray and infrared absorption spectroscopic studies of neptunium in sodium silicate glass

    SciTech Connect

    Veal, B.W.; Carnall, W.T.; Dunlap, B.D.; Mitchell, A.W.; Lam, D.J.

    1986-04-01

    The valence state of neptunium ions in sodium silicate glasses prepared under reducing and oxidizing conditions has been investigated by the x-ray photoelectron, Moessbauer and optical absorption spectroscopic techniques. Results indicate that the Np ions are tetravalent in glasses prepared under reducing conditions and pentavalent in glasses prepared under oxidizing conditions.

  8. Absorption spectroscopic study of EDA complexes of [70] fullerene with a series of methyl benzenes

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sumanta; Nayak, Sandip K.; Chattopadhyay, Subrata K.; Banerjee, Manas; Mukherjee, Asok K.

    2001-02-01

    [70]Fullerene has been shown to form 1:1 molecular complexes with toluene, p-xylene, m-xylene, 1,2,4,5-tetramethyl benzene (durene) and pentamethyl benzene (PMB) in CCl 4 medium by absorption spectroscopic method. Isosbestic points have been detected in case of complexes with PMB and durene. Charge transfer absorption band could not be detected but the intensity of the broad absorption band of C 70 in CCl 4 decreases systematically with increase in the concentration of the added methylbenzenes. From this trend the formation constants ( Kc) of the complexes have been determined at three different wavelengths. The constancy of Kc with respect to change in the wavelength of measurement supports the view that complex of a single stoichiometry (1:1) is formed in each case.

  9. Spectroscopic and Geochemical Analyses of Ferrihydrite from Hydrothermal Springs in Iceland and Applications to Mars

    NASA Technical Reports Server (NTRS)

    Bishop, Janice; Murad, E.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Ferrihydrite samples were collected from a thermal spring and a cold stream in the Landmannalaugar region of Iceland. Chemical and spectroscopic analyses have been performed on the air-dried and fine-grained fractions of these samples. The ferrihydrite from the cold stream is a pure sample, containing small amounts of Ca, P and Si, which do not form minerals detectable with X-ray diffraction (XRD) or reflectance and transmittance spectroscopy. The ferrihydrite from the thermal pool is a less pure sample, containing larger amounts of amorphous Si and P. The XRD and spectral features for this sample are also consistent with a less crystalline structure. Some of the Si is incorporated in the structure of the ferrihydrite. The Ca, P and possibly some of the Si may be biogenic. The spectral character of these Icelandic ferrihydrites is compared with those of synthetic ferrihydrites and other iron oxide/oxyhydroxide minerals. Ferrihydrite is characterized by a broad Fe3+ excitation band near 0.92 microns (approx. 10900/cm) and a strong Fe-O absorption feature near 475/cm (approx. 21 microns) in transmittance spectra. Multiple bands due to H2O and OH are also present for ferrihydrite. Natural ferrihydrites frequently exhibit a band near 950-1050/cm (approx. 10 microns) that is typically not observed for synthetic ferrihydrites and may be due to some Si in the structure. An additional pair of spectral bands near 1400 and 1500/cm (approx. 7 microns) are characteristic of pure ferrihydrites from natural and synthetic sources. Hydrothermal springs may have been present at one time on Mars in association with volcanic activity. Ferrihydrite formation in such an environment may have contributed to the ferric oxide-rich surface material on Mars.

  10. No microplastics in benthic eelpout (Zoarces viviparus): An urgent need for spectroscopic analyses in microplastic detection.

    PubMed

    Wesch, Charlotte; Barthel, Anne-Kathrin; Braun, Ulrike; Klein, Roland; Paulus, Martin

    2016-07-01

    Monitoring the ingestion of microplastics is challenging and suitable detection techniques are insufficiently used. Thus, misidentifying natural for synthetic microfibres cannot be avoided. As part of a framework to monitor the ingestion of microplastics in eelpout, this short report addresses the accurate identification of microfibres. We show that, following visual inspections, putatively synthetic microfibres are indeed of natural origin, as ascertained by spectrometric analyses. Consequently, we call for an inclusion of spectroscopic techniques in standardized microplastic monitoring schemes. PMID:27198628

  11. Spectroscopic Analyses of the Biofuels-Critical Phytochemical Coniferyl Alcohol and Its Enzyme-Catalyzed Oxidation Products

    SciTech Connect

    Achyuthan, Komandoor; Adams, Paul; Simmons, Blake; Singh, Anup

    2011-07-13

    Lignin composition (monolignol types of coniferyl, sinapyl or p-coumaryl alcohol) is causally related to biomass recalcitrance. We describe multiwavelength (220, 228, 240, 250, 260, 290, 295, 300, 310 or 320 nm) absorption spectroscopy of coniferyl alcohol and its laccase- or peroxidase-catalyzed products during real time kinetic, pseudo-kinetic and endpoint analyses, in optical turn on or turn off modes, under acidic or basic conditions. Reactions in microwell plates and 100 mu L volumes demonstrated assay miniaturization and high throughput screening capabilities. Bathochromic and hypsochromic shifts along with hyperchromicity or hypochromicity accompanied enzymatic oxidations by laccase or peroxidase. The limits of detection and quantitation of coniferyl alcohol averaged 2.4 and 7.1 mu M respectively, with linear trend lines over 3 to 4 orders of magnitude. Coniferyl alcohol oxidation was evident within 10 minutes or with 0.01 mu g/mL laccase and 2 minutes or 0.001 mu g/mL peroxidase. Detection limit improved to 1.0 mu M coniferyl alcohol with Km of 978.7 +/- 150.7 mu M when examined at 260 nm following 30 minutes oxidation with 1.0 mu g/mL laccase. Our assays utilized the intrinsic spectroscopic properties of coniferyl alcohol or its oxidation products for enabling detection, without requiring chemical synthesis or modification of the substrate or product(s). These studies facilitate lignin compositional analyses and augment pretreatment strategies for reducing biomass recalcitrance.

  12. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    SciTech Connect

    Westre, T.E.

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s{yields}3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  13. Near-infrared diode laser based spectroscopic detection of ammonia: a comparative study of photoacoustic and direct optical absorption methods

    NASA Technical Reports Server (NTRS)

    Bozoki, Zoltan; Mohacsi, Arpad; Szabo, Gabor; Bor, Zsolt; Erdelyi, Miklos; Chen, Weidong; Tittel, Frank K.

    2002-01-01

    A photoacoustic spectroscopic (PAS) and a direct optical absorption spectroscopic (OAS) gas sensor, both using continuous-wave room-temperature diode lasers operating at 1531.8 nm, were compared on the basis of ammonia detection. Excellent linear correlation between the detector signals of the two systems was found. Although the physical properties and the mode of operation of both sensors were significantly different, their performances were found to be remarkably similar, with a sub-ppm level minimum detectable concentration of ammonia and a fast response time in the range of a few minutes.

  14. X-Ray Absorption Spectroscopic Characterization of the Molybdenum Site of 'Escherichia Coli' Dimethyl Sulfoxide Reductase

    SciTech Connect

    George, G.N.; Doonan, C.J.; Rothery, R.A.; Boroumand, N.; Weiner, J.H.; /Saskatchewan U. /Alberta U.

    2007-07-09

    Structural studies of dimethyl sulfoxide (DMSO) reductases were hampered by modification of the active site during purification. We report an X-ray absorption spectroscopic analysis of the molybdenum active site of Escherichia coli DMSO reductase contained within its native membranes. The enzyme in these preparations is expected to be very close to the form found in vivo. The oxidized active site was found to have four Mo-S ligands at 2.43 angstroms, one Mo=O at 1.71 angstroms, and a longer Mo-O at 1.90 angstroms. We conclude that the oxidized enzyme is a monooxomolybdenum(VI) species coordinated by two molybdopterin dithiolenes and a serine. The bond lengths determined for E. coli DMSO reductase are very similar to those determined for the well-characterized Rhodobacter sphaeroides DMSO reductase, suggesting similar active site structures for the two enzymes. Furthermore, our results suggest that the form found in vivo is the monooxobis(molybdopterin) species.

  15. Analyzing cell structure and dynamics with confocal light scattering and absorption spectroscopic microscopy

    NASA Astrophysics Data System (ADS)

    Qiu, Le; Vitkin, Edward; Fang, Hui; Zaman, Munir M.; Andersson, Charlotte; Salahuddin, Saira; Modell, Mark D.; Freedman, Steven D.; Hanlon, Eugene B.; Itzkan, Irving; Perelman, Lev T.

    2007-02-01

    We recently developed a new microscopic optical technique capable of noninvasive analysis of cell structure and cell dynamics on the submicron scale [1]. It combines confocal microscopy, a well-established high-resolution microscopic technique, with light scattering spectroscopy (LSS) and is called confocal light absorption and scattering spectroscopic (CLASS) microscopy. CLASS microscopy requires no exogenous labels and is capable of imaging and continuously monitoring individual viable cells, enabling the observation of cell and organelle functioning at scales on the order of 100 nm. To test the ability of CLASS microscopy to monitor cellular dynamics in vivo we performed experiments with human bronchial epithelial cells treated with DHA and undergoing apoptosis. The treated and untreated cells show not only clear differences in organelle spatial distribution but time sequencing experiments on a single cell show disappearance of certain types of organelles and change of the nuclear shape and density with the progression of apoptosis. In summary, CLASS microscopy provides an insight into metabolic processes within the cell and opens doors for the noninvasive real-time assessment of cellular dynamics. Noninvasive monitoring of cellular dynamics with CLASS microscopy can be used for a real-time dosimetry in a wide variety of medical and environmental applications that have no immediate observable outcome, such as photodynamic therapy, drug screening, and monitoring of toxins.

  16. Catalog of Narrow Mg II Absorption Lines in the Baryon Oscillation Spectroscopic Survey

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Fu; Gu, Qiu-Sheng; Chen, Yan-Mei

    2015-12-01

    Using the Data Release 9 Quasar spectra from the Baryonic Oscillation Spectroscopic Survey, which does not include quasar spectra from the Sloan Digital Sky Survey Data Release 7, we detect narrow Mg ii λλ2796, 2803 absorption doublets in the spectral data redward of 1250 Å (quasar rest frame) until the red wing of the Mg ii λ2800 emission line. Our survey is limited to quasar spectra with a median signal-to-noise ratio < {{S}}/{{N}}> ≥slant 4 pixel-1 in the surveyed spectral region, resulting in a sample that contains 43,260 quasars. We have detected a total of 18,598 Mg ii absorption doublets with 0.2933 ≤ zabs ≤ 2.6529. About 75% of absorbers have an equivalent width at rest frame of {W}rλ 2796≥slant 1 \\mathringA . About 75% of absorbers have doublet ratios ({DR}={W}rλ 2796/{W}rλ 2803) in the range of 1 ≤ DR ≤ 2, and about 3.2% lie outside the range of 1 - σDR ≤ DR ≤ 2 + σDR. We characterize the detection false positives/negatives by the frequency of detected Mg ii absorption doublets in the limits of the S/N of the spectral data. The S/N = 4.5 limit is assigned a completeness fraction of 53% and tends to be complete when the S/N is greater than 4.5. The redshift number densities of all of the detected Mg ii absorbers moderately increase from z ≈ 0.4 to z ≈ 1.5, which parallels the evolution of the cosmic star formation rate density. Limiting our investigation to those quasars whose emission redshift can be determined from narrow emission lines, the relative velocities (β) of Mg ii absorbers have a complex distribution which probably consists of three classes of Mg ii absorbers: (1) cosmologically intervening absorbers; (2) environmental absorbers that reside within the quasar host galaxies or galaxy clusters; (3) quasar outflow absorbers. After subtracting contributions from cosmologically intervening absorbers and environmental absorbers, the β distribution of the Mg iiabsorbers might mainly be contributed by the quasar outflow

  17. Confocal Light Absorption and Scattering Spectroscopic (CLASS) imaging: From cancer detection to sub-cellular function

    NASA Astrophysics Data System (ADS)

    Qiu, Le

    Light scattering spectroscopy (LSS), an optical technique that relates the spectroscopic properties of light elastically scattered by small particles to their size, refractive index and shape, has been recently successfully employed for sensing morphological and biochemical properties of epithelial tissues and cells in vivo. LSS does not require exogenous markers, is non-invasive, and, due to its multispectral nature, can sense biological structures well beyond the diffraction limit. All that makes LSS be a very good candidate to be used both in clinical medicine for in vivo detection of disease and in cell biology to monitor cell function on the organelle scale. Recently we developed two LSS-based imaging modalities: clinical Polarized LSS (PLSS) Endoscopic Technique for locating early pre-cancerous changes in GI tract and Confocal Light Absorption and Scattering Spectroscopic (CLASS) Microscopy for studying cells in vivo without exogenous markers. One important application of the clinical PLSS endoscopic instrument, a noncontact scanning imaging device compatible with the standard clinical endoscopes and capable of detecting dysplastic changes, is to serve as a guide for biopsy in Barrett's esophagus (BE). The instrument detects parallel and perpendicular components of the polarized light, backscattered from epithelial tissues, and determines characteristics of epithelial nuclei from the residual spectra. It also can find tissue oxygenation, hemoglobin content and other properties from the diffuse light component. By rapidly scanning esophagus the PLSS endoscopic instrument makes sure the entire BE portion is scanned and examined for the presence of dysplasia. CLASS microscopy, on the other hand, combines principles of light scattering spectroscopy (LSS) with confocal microscopy. Its main purpose is to image cells on organelle scale in vivo without the use of exogenous labels which may affect the cell function. The confocal geometry selects specific region and

  18. Spectroscopic Character and Spatial Distribution of Hydroxyl and Water Absorption Features Measured on the Lunar Surface by the Moon Mineralogy Mapper Imaging Spectrometer on Chandrayaan-1

    NASA Astrophysics Data System (ADS)

    Green, R. O.; Pieters, C. M.; Goswami, J.; Clark, R. N.; Annadurai, M.; Boardman, J. W.; Buratti, B. J.; Combe, J.; Dyar, M. D.; Head, J. W.; Hibbitts, C.; Hicks, M.; Isaacson, P.; Klima, R. L.; Kramer, G. Y.; Kumar, S.; Livo, K. E.; Lundeen, S.; Malaret, E.; McCord, T. B.; Mustard, J. F.; Nettles, J. W.; Petro, N. E.; Runyon, C. J.; Staid, M.; Sunshine, J. M.; Taylor, L. A.; Tompkins, S.; Varanasi, P.

    2009-12-01

    The Moon Mineralogy Mapper imaging spectrometer on Chandrayaan-1 has a broad spectral range from 430 to 3000 nm. By design, the range was specified to extend to 3000 nm to allow for possible detection of trace volatile compounds that possess absorption bands near 3000 nm. Soon after acquisition and calibration of a large fraction of the lunar surface in early February 2009, absorption features in the 2700 to 3000 nm region were detected over unexpectedly large regional areas. This extraordinary discovery has withstood extensive re-analysis and falsification efforts. We have concluded these absorption features are fundamentally present in the M3 measurements and are indicators of extensive hydroxyl and water-bearing materials occurring on the surface of the Moon. Based on current analyses, these absorption features appear strongest at high latitudes, but also occur in association with several fresh feldspathic craters. Interestingly, the distribution of these absorption features are not directly correlated with existing neutron spectrometer hydrogen abundance data for the sunlight surface. This may indicate that the formation and retention of hydroxyl and water is an active process largely restricted to the upper most surface. We present the detailed spectroscopic character of these absorption features in the 2700 to 3000 nm spectral region, including selected examples through all levels of measurement processing from raw data to calibrated apparent surface reflectance. In summary we show the measured strength and latitudinal distribution of the absorptions as well as selected localized occurrences in association with fresh feldspathic craters. The presence of hydroxyl and water bearing material over extensive regions of the lunar surface provides a new and unexpected source of volatiles. Options for harvesting these elements directly from the regolith may provide an alternate supply of volatiles for long term human exploration objectives.

  19. Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy).

    PubMed

    De Luca, Raffaella; Gigliotti, Valentina; Panarello, Mario; Bloise, Andrea; Crisci, Gino M; Miriello, Domenico

    2016-01-15

    This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples. PMID:26311479

  20. Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy)

    NASA Astrophysics Data System (ADS)

    De Luca, Raffaella; Gigliotti, Valentina; Panarello, Mario; Bloise, Andrea; Crisci, Gino M.; Miriello, Domenico

    2016-01-01

    This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples.

  1. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    NASA Astrophysics Data System (ADS)

    Anselmi, Massimiliano; Marocchi, Simone; Aschi, Massimiliano; Amadei, Andrea

    2012-01-01

    Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  2. Reactivity of Chromium(III) Nutritional Supplements in Biological Media: An X-Ray Absorption Spectroscopic Study

    SciTech Connect

    Nguyen, A.; Mulyani, I.; Levina, A.; Lay, P.A.

    2009-05-22

    Chromium(III) nutritional supplements are widely used due to their purported ability to enhance glucose metabolism, despite growing evidence on low activity and the potential genotoxicity of these compounds. Reactivities of Cr(III) complexes used in nutritional formulations, including [Cr3O(OCOEt)6(OH2)3]+ (A), [Cr(pic)3] (pic) = 2-pyridinecarboxylato(-) (B), and trans-[CrCl2(OH2)4]+ (CrCl3 {center_dot} 6H2O; C), in a range of natural and simulated biological media (artificial digestion systems, blood and its components, cell culture media, and intact L6 rat skeletal muscle cells) were studied by X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectroscopic data were processed by multiple linear-regression analyses with the use of a library of model Cr(III) compounds, and the results were corroborated by the results of X-ray absorption fine structure spectroscopy and electrospray mass spectrometry. Complexes A and B underwent extensive ligand-exchange reactions under conditions of combined gastric and intestinal digestion (in the presence of a semisynthetic meal, 3 h at 310 K), as well as in blood serum and in a cell culture medium (1-24 h at 310 K), with the formation of Cr(III) complexes with hydroxo and amino acid/protein ligands. Reactions of compounds A-C with cultured muscle cells led to similar ligand-exchange products, with at least part of Cr(III) bound to the surface of the cells. The reactions of B with serum greatly enhanced its propensity to be converted to Cr(VI) by biological oxidants (H2O2 or glucose oxidase system), which is proposed to be a major cause of both the insulin-enhancing activity and toxicity of Cr(III) compounds (Mulyani, I.; Levina, A.; Lay, P. A. Angew. Chem. Int. Ed. 2004, 43, 4504-4507). This finding enhances the current concern over the safety of consumption of large doses of Cr(III) supplements, particularly [Cr(pic)3].

  3. Absorption properties of type-II InAs/InAsSb superlattices measured by spectroscopic ellipsometry

    SciTech Connect

    Webster, P. T.; Riordan, N. A.; Liu, S.; Zhang, Y.-H.; Johnson, S. R.; Steenbergen, E. H.

    2015-02-09

    Strain-balanced InAs/InAsSb superlattices offer access to the mid- to long-wavelength infrared region with what is essentially a ternary material system at the GaSb lattice constant. The absorption coefficients of InAs/InAsSb superlattices grown by molecular beam epitaxy on (100)-oriented GaSb substrates are measured at room temperature over the 30 to 800 meV photon energy range using spectroscopic ellipsometry, and the miniband structure of each superlattice is calculated using a Kronig-Penney model. The InAs/InAsSb conduction band offset is used as a fitting parameter to align the calculated superlattice ground state transition energy to the measured absorption onset at room temperature and to the photoluminescence peak energy at low temperature. It is observed that the ground state absorption coefficient and transition strength are proportional to the square of the wavefunction overlap and the ground state absorption coefficient approaches a maximum value of around 5780 cm{sup −1} as the wavefunction overlap approaches 100%. The absorption analysis of these samples indicates that the optical joint density of states is weakly dependent on the period thickness and Sb content of the superlattice, and that wavefunction overlap is the principal design parameter in terms of obtaining strong absorption in these structures.

  4. Absorption properties of type-II InAs/InAsSb superlattices measured by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Webster, P. T.; Riordan, N. A.; Liu, S.; Steenbergen, E. H.; Synowicki, R. A.; Zhang, Y.-H.; Johnson, S. R.

    2015-02-01

    Strain-balanced InAs/InAsSb superlattices offer access to the mid- to long-wavelength infrared region with what is essentially a ternary material system at the GaSb lattice constant. The absorption coefficients of InAs/InAsSb superlattices grown by molecular beam epitaxy on (100)-oriented GaSb substrates are measured at room temperature over the 30 to 800 meV photon energy range using spectroscopic ellipsometry, and the miniband structure of each superlattice is calculated using a Kronig-Penney model. The InAs/InAsSb conduction band offset is used as a fitting parameter to align the calculated superlattice ground state transition energy to the measured absorption onset at room temperature and to the photoluminescence peak energy at low temperature. It is observed that the ground state absorption coefficient and transition strength are proportional to the square of the wavefunction overlap and the ground state absorption coefficient approaches a maximum value of around 5780 cm-1 as the wavefunction overlap approaches 100%. The absorption analysis of these samples indicates that the optical joint density of states is weakly dependent on the period thickness and Sb content of the superlattice, and that wavefunction overlap is the principal design parameter in terms of obtaining strong absorption in these structures.

  5. Spectroscopic analyses of the parent stars of extrasolar planetary system candidates

    NASA Astrophysics Data System (ADS)

    Gonzalez, Guillermo

    1998-06-01

    The stars rho () 1 Cnc, rho CrB, 16 Cyg B, 51 Peg, 47 UMa, 70 Vir, and HD 114762 have recently been proposed to harbor planetary mass companions based on small amplitude radial velocity variations. From spectroscopic analyses we derive the following values of [Fe/H] for these stars: 0.29, -0.29, 0.06, 0.21, 0.01, -0.03, and -0.60 (all with an uncertainty of 0.06 dex), respectively; the [Fe/H] value for 16 Cyg A is 0.11. The four 51 Peg-like systems, upsilon And, tau Boo, rho () 1 Cnc, and 51 Peg, have a mean [Fe/H] value of 0.25. Otherwise, the abundance patterns, expressed as [X/Fe], are approximately solar. We used Fourier analysis, supplemented by line profile synthesis, to derive the following v sin i values: <1.3, 1.4 +/- 0.3, 1.7 +/- 0.4, < 0.5, and < 1.5 km s(-1) for rho () 1 Cnc, 51 Peg, 47 UMa, 70 Vir, and HD 114762, respectively. A similar analysis of the spectrum of rho CrB (with a lower resolving power) yields a value of ~ 1.5 km s() -1. Combining these data with published estimates of v sin i and rotation periods and assuming that the radial velocity variations are due to the presence of planets, we derive the following masses for the companions: >0.66, 2.9(+13.6}_{-1.3) , 0.49+/-0.03, 3.4() +3.1_-1.1, >9.4, and >10.4 cal M_J for rho () 1 Cnc, rho CrB, 51 Peg, 47 UMa, 70 Vir, and HD 114762, respectively; the mass of 16 Cyg B b, calculated using a published estimate for sin i, is 2.0() +1.1_-0.3 cal M_J. The masses of the companions to upsilon And and tau Boo, which were analyzed in a previous paper, are 0.76() +0.19_-0.03 and 5.9() +43.9_-1.8 cal M_J, respectively. We confirm previous claims that rho () 1 Cnc appears to be a subgiant. However, the theoretical isochrone-derived age is much greater than the age of the universe. At this time we have insufficient data to determine the true nature of rho () 1 Cnc, but we suggest that it may be an unresolved stellar binary viewed nearly pole-on. A search for line profile variations might help to resolve this

  6. Interaction between indium tin oxide nanoparticles and cytochrome c: A surface-enhanced Raman scattering and absorption spectroscopic study

    SciTech Connect

    Yang, Yimin E-mail: tqiu@seu.edu.cn; Du, Deyang; Fan, Jiyang; Qiu, Teng E-mail: tqiu@seu.edu.cn; Kong, Fan

    2015-06-28

    Indium-tin-oxide (ITO) nanoparticles were annealed in vacuum or reducing atmosphere to obtain different surface structures and investigate their influence on the adsorptive character and conformation of cytochrome c (Cyt c) molecule. Annealing-induced morphometric or structural changes of ITO nanoparticles were characterized by instruments of transmission electron microscopy, x-ray diffraction, and Raman scattering. Semiconductor ITO nanoparticle-enhanced Raman scattering of Cyt c was observed and the enhanced efficiency was found to closely depend on the surface structures which control the adsorbance of buffer anions needed for Cyt c loading. Direct electron transfer between Cyt c and ITO surface at the moment of molecular elastic collision was found and a reverse electron transfer process for O-terminated surface and metal-terminated surface was observed, according to absorption spectroscopic measurement on the residual solution.

  7. THERMAL AND SPECTROSCOPIC ANALYSES OF CAUSTIC SIDE SOLVENT EXTRACTION SOLVENT CONTACTED WITH 1 MOLARAND 3 MOLAR NITRIC ACID

    SciTech Connect

    Fondeur, F; David Hobbs, D; Samuel Fink, S

    2007-07-23

    Thermal and spectroscopic analyses were performed on multiple layers formed from contacting Caustic Side Solvent Extraction (CSSX) solvent with 1 M or 3 M nitric acid. A slow chemical reaction occurs (i.e., over several weeks) between the solvent and 1 M or 3 M nitric acid as evidenced by color changes and the detection of nitro groups in the infrared spectrum of the aged samples. Thermal analysis revealed that decomposition of the resulting mixture does not meet the definition of explosive or deflagrating material.

  8. THERMAL AND SPECTROSCOPIC ANALYSES OF CAUSTIC LIDE SOLVENT EXTRACTION SOLVENT CONTACTED WITH 16 MOLAR AND 8 MOLAR NITRIC ACID

    SciTech Connect

    Fondeur, F; David Hobbs, D; Samuel Fink, S

    2007-07-12

    Thermal and spectroscopic analyses were performed on multiple layers formed from contacting Caustic Side Solvent Extraction (CSSX) solvent with 1 M or 3 M nitric acid. A slow chemical reaction occurs (i.e., over several weeks) between the solvent and 1 M or 3 M nitric acid as evidenced by color changes and the detection of nitro groups in the infrared spectrum of the aged samples. Thermal analysis revealed that decomposition of the resulting mixture does not meet the definition of explosive or deflagrating material.

  9. X-ray absorption spectroscopic characterization of a cytochrome P450 compound II derivative

    PubMed Central

    Newcomb, Martin; Halgrimson, James A.; Horner, John H.; Wasinger, Erik C.; Chen, Lin X.; Sligar, Stephen G.

    2008-01-01

    The cytochrome P450 enzyme CYP119, its compound II derivative, and its nitrosyl complex were studied by iron K-edge x-ray absorption spectroscopy. The compound II derivative was prepared by reaction of the resting enzyme with peroxynitrite and had a lifetime of ≈10 s at 23°C. The CYP119 nitrosyl complex was prepared by reaction of the enzyme with nitrogen monoxide gas or with a nitrosyl donor and was stable at 23°C for hours. Samples of CYP119 and its derivatives were studied by x-ray absorption spectroscopy at temperatures below 140 (K) at the Advanced Photon Source of Argonne National Laboratory. The x-ray absorption near-edge structure spectra displayed shifts in edge and pre-edge energies consistent with increasing effective positive charge on iron in the series native CYP119 < CYP119 nitrosyl complex < CYP119 compound II derivative. Extended x-ray absorption fine structure spectra were simulated with good fits for k = 12 Å−1 for native CYP119 and k = 13 Å−1 for both the nitrosyl complex and the compound II derivative. The important structural features for the compound II derivative were an iron-oxygen bond length of 1.82 Å and an iron-sulfur bond length of 2.24 Å, both of which indicate an iron-oxygen single bond in a ferryl-hydroxide, FeIVOH, moiety. PMID:18174331

  10. Spectroscopic method for determination of the absorption coefficient in brain tissue

    NASA Astrophysics Data System (ADS)

    Johansson, Johannes D.

    2010-09-01

    I use Monte Carlo simulations and phantom measurements to characterize a probe with adjacent optical fibres for diffuse reflectance spectroscopy during stereotactic surgery in the brain. Simulations and measurements have been fitted to a modified Beer-Lambert model for light transport in order to be able to quantify chromophore content based on clinically measured spectra in brain tissue. It was found that it is important to take the impact of the light absorption into account when calculating the apparent optical path length, lp, for the photons in order to get good estimates of the absorption coefficient, μa. The optical path length was found to be well fitted to the equation lp=a+b ln(Is)+c ln(μa)+d ln(Is)ln(μa), where Is is the reflected light intensity for scattering alone (i.e., zero absorption). Although coefficients a-d calculated in this study are specific to the probe used here, the general form of the equation should be applicable to similar probes.

  11. Total CMB analysis of streaker aerosol samples by PIXE, PIGE, beta- and optical-absorption analyses

    NASA Astrophysics Data System (ADS)

    Annegarn, H. J.; Przybylowicz, W. J.

    1993-04-01

    Multielemental analyses of aerosol samples are widely used in air pollution receptor modelling. Specifically, the chemical mass balance (CMB) model has become a powerful tool in urban air quality studies. Input data required for the CMB includes not only the traditional X-ray fluorescence (and hence PIXE) detected elements, but also total mass, organic and inorganic carbon, and other light elements including Mg, Na and F. The circular streaker sampler, in combination with PIXE analysis, has developed into a powerful tool for obtaining time-resolved, multielemental aerosol data. However, application in CMB modelling has been limited by the absence of total mass and complementary light element data. This study reports on progress in using techniques complementary to PIXE to obtain additional data from circular streaker samples, maintaining the nondestructive, instrumental approach inherent in PIXE: beta-gauging using a 147Pm source for total mass; optical absorption for inorganic carbon; and PIGE to measure the lighter elements.

  12. FT-IR spectroscopic analyses of 3-Methyl-5-Pyrazolone (MP)

    NASA Astrophysics Data System (ADS)

    El-Nahass, M. M.; Kamel, M. A.; El-Barbary, A. A.; El-Mansy, M. A. M.; Ibrahim, M.

    2013-07-01

    In the present work both experimental and computational FT-IR spectroscopic studies on 3-Methyl-5-Pyrazolone (MP) were reported. Experimental FT-IR spectrum for MP compound is recorded in powder form. Important physical parameters were reported such as structural parameters, vibrational frequencies, entropy, total energy, total dipole moment and HOMO-LUMO energy gap using DFT/B3LYP/6-311G(d,p) basis set. MP molecule has a total dipole moment of 2.83 Debye and HOMO-LUMO energy gap of 5.80 eV. Results indicate also that exposure to UV changes the spin from singlet to doublet state; one can conclude that MP compound may undergo anomalous Zeeman like effect.

  13. Spectroscopic analyses of Fe and water in clays: A Martian surface weathering study

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Pieters, Carle M.; Edwards, J. O.; Coyne, L. M.; Chang, S.

    1991-01-01

    Martian surface morphology suggests the presence of liquid H2O on Mars in the past. Reflectance spectra of the Martian surface include features which correspond to the crystal field transitions of iron, as well as features supporting the presence of ice and minerals containing structural OH and surface water. Researchers initiated further spectroscopic studies of surface iron and water and structural OH in clays in order to determine what remotely obtained spectra can indicate about the presence of clays on Mars based on a clearer understanding of the factors influencing the spectral features. Current technology allows researchers to better correlate the low frequency fundamental stretching and bending vibrations of O-H bonds with the diagnostic near infrared overtone and combination bands used in mineral characterization and identification.

  14. Asymmetry between absorption and photoluminescence line shapes of TPD: spectroscopic fingerprint of the twisted biphenyl core.

    PubMed

    Scholz, Reinhard; Gisslén, Linus; Himcinschi, Cameliu; Vragović, Igor; Calzado, Eva M; Louis, Enrique; San Fabián Maroto, Emilio; Díaz-García, María A

    2009-01-01

    We analyze absorption, photoluminescence (PL), and resonant Raman spectra of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), with the aim of providing a microscopic interpretation of a significant Stokes shift of about 0.5 eV that makes this material suitable for stimulated emission. The optical spectra were measured for TPD dissolved in toluene and chloroform, as well as for polystyrene films doped with varying amounts of TPD. In addition, we measured preresonant and resonant Raman spectra, giving direct access to the vibrational modes elongated in the relaxed excited geometry of the molecule. The experimental data are interpreted with calculations of the molecular geometry in the electronic ground state and the optically excited state using density functional theory. Several strongly elongated high-frequency modes within the carbon rings results in a vibronic progression with a calculated spacing of 158 meV, corroborated by the observation of vibrational sidebands in the PL spectra. The peculiarities of the potential energy surfaces related to a twisting around the central bond in the biphenyl core of TPD allow to quantify the asymmetry between the line shapes observed in absorption and emission. PMID:19086796

  15. Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of some fluoroquinolone antibacterials using ammonium reineckate

    NASA Astrophysics Data System (ADS)

    Al-Ghannam, Sheikha M.

    2008-04-01

    Three accurate, rapid and simple atomic absorption spectrometric (AAS), conductometric and colorimetric methods were developed for the determination of gatifloxacin (GTF), moxifloxacin (MXF) and sparfloxacin (SPF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at λmax 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone. The optimizations of various experimental conditions were described. Optimum concentration ranges for the determination of GTF, MXF and SPF were 5.0-150, 40-440 μg mL -1 and 0.10-1.5 mg mL -1 using atomic absorption (AAS), conductometric and colorimetric methods, respectively. Detection and quantification limits are ranges from 1.5 to 2.3 μg mL -1 using AAS method or 30-45 μg mL -1 using colorimetric method. The proposed procedures have been applied successfully to the analysis of these drugs in pharmaceutical formulations and the results are favourably comparable to the reference methods.

  16. Spectroscopic analyses of chemical adaptation processes within microalgal biomass in response to changing environments.

    PubMed

    Vogt, Frank; White, Lauren

    2015-03-31

    Via photosynthesis, marine phytoplankton transforms large quantities of inorganic compounds into biomass. This has considerable environmental impacts as microalgae contribute for instance to counter-balancing anthropogenic releases of the greenhouse gas CO2. On the other hand, high concentrations of nitrogen compounds in an ecosystem can lead to harmful algae blooms. In previous investigations it was found that the chemical composition of microalgal biomass is strongly dependent on the nutrient availability. Therefore, it is expected that algae's sequestration capabilities and productivity are also determined by the cells' chemical environments. For investigating this hypothesis, novel analytical methodologies are required which are capable of monitoring live cells exposed to chemically shifting environments followed by chemometric modeling of their chemical adaptation dynamics. FTIR-ATR experiments have been developed for acquiring spectroscopic time series of live Dunaliella parva cultures adapting to different nutrient situations. Comparing experimental data from acclimated cultures to those exposed to a chemically shifted nutrient situation reveals insights in which analyte groups participate in modifications of microalgal biomass and on what time scales. For a chemometric description of these processes, a data model has been deduced which explains the chemical adaptation dynamics explicitly rather than empirically. First results show that this approach is feasible and derives information about the chemical biomass adaptations. Future investigations will utilize these instrumental and chemometric methodologies for quantitative investigations of the relation between chemical environments and microalgal sequestration capabilities. PMID:25813024

  17. Spectroscopic evaluation of the interaction between pesticides and chickpea cystatin: comparative binding and toxicity analyses.

    PubMed

    Bhat, Sheraz Ahmad; Bhat, Waseem Feeroze; Bano, Bilqees

    2016-07-13

    The binding study of pesticides with proteins is of great importance in ecotoxicology. In this study, a comparative interaction mechanism of phytocystatin with three pesticides has been presented, each from a different class-glyphosate herbicide (GPS), chlorpyrifos insecticide (CPF), and mancozeb fungicide (MCZ). The interaction of purified chickpea cystatin (CPC) has been characterized by fluorescence, UV, and circular dichroism (CD) spectroscopic methods. The study revealed association constants (Ka) of 52 M(-1), 1.145 × 10(3) M(-1), and 36.12 M(-1) for the interaction of CPF, MCZ, and GPS with CPC, respectively, signifying the high affinity interaction for MCZ. Structural changes (at tertiary and secondary levels) were confirmed by UV-visible, intrinsic fluorescence and CD spectroscopy. The results showed that the effect on the CPC structure was more pronounced in the case of MCZ, which was followed by CPF and then GPS. The functional analysis of the pesticide treated inhibitor showed a decline in antipapain activity which varied with the time and dose as well as the class of pesticide. MCZ was relatively much more toxic as compared to CPF and GPS. Reactive oxygen species responsible for inhibitor damage were also analyzed. The results obtained implicate that the exposure of plants to pesticides may lead to physicochemical changes in proteins such as phytocystatins leading to physiological damage to the plant system. PMID:27327564

  18. 2D NMR spectroscopic analyses of archangelicin from the seeds of Angelica archangelica.

    PubMed

    Muller, Melanie; Byres, Maureenx; Jaspars, Marcel; Kumarasamy, Yashodharan; Middleton, Moira; Nahar, Lutfun; Shoeb, Mohammad; Sarker, Satyajit D

    2004-12-01

    A total of six coumarins, bergapten (1), xanthotoxin (2), imperatorin (3), isoimperatorin (4), phellopterin (5) and archangelicin (6), have been isolated from an n-hexane extract of the seeds of Angelica archangelica. The results of comprehensive 2D NMR analyses of archangelicin are discussed. PMID:15634612

  19. LOCAL HELIOSEISMIC AND SPECTROSCOPIC ANALYSES OF INTERACTIONS BETWEEN ACOUSTIC WAVES AND A SUNSPOT

    SciTech Connect

    Rajaguru, S. P.; Wachter, R.; Couvidat, S.; Sankarasubramanian, K.

    2010-10-01

    Using a high-cadence imaging spectropolarimetric observation of a sunspot and its surroundings in magnetically sensitive (Fe I 6173 A) and insensitive (Fe I 7090 A) upper photospheric absorption lines, we map the instantaneous wave phases and helioseismic travel times as a function of observation height and inclination of magnetic field to the vertical. We confirm the magnetic inclination-angle-dependent transmission of incident acoustic waves into upward propagating waves and derive (1) proof that helioseismic travel times receive direction-dependent contributions from such waves and hence cause errors in conventional flow inferences, (2) evidences for acoustic wave sources beneath the umbral photosphere, and (3) significant differences in travel times measured from the chosen magnetically sensitive and insensitive spectral lines.

  20. X-ray absorption fine structure spectroscopic study of uranium nitrides

    SciTech Connect

    Poineau, Frederic; Yeamans, Charles B.; Cerefice, Gary S.; Sattelberger, Alfred P; Czerwinski, Ken R.

    2012-01-01

    Uranium mononitride (UN), sesquinitride (U2N3) and dinitride (UN2) were characterized by extended X-Ray absorption fine structure spectroscopy. Analysis on UN indicate the presence of three uranium shells at distances of 3.46(3), 4.89(5) and 6.01(6) A and a nitrogen shell at a distance of 2.46(2) A . For U2N3, two absorbing uranium atoms at different crystallographic positions are present in the structure. One of the uranium atoms is surrounded by nitrogen atoms at 2.28(2) A and by uranium atoms at 3.66(4) and 3.95(4) A . The second type of uranium atom is surrounded by nitrogen atoms at 2.33(2) and 2.64(3) A and by uranium atoms at 3.66(4), 3.95(4) and 5.31(5) A . Results on UN2 indicate two uranium shells at 3.71(4) and 5.32(5) A and two nitrogen shells at 2.28(2).

  1. Spectroscopic and x-ray diffraction analyses of asbestos in the World Trade Center dust:

    USGS Publications Warehouse

    Swayze, Gregg A.; Clark, Roger N.; Sutley, Stephen J.; Hoefen, Todd M.; Plumlee, Geoffrey S.; Meeker, Gregory P.; Brownfield, Isabelle; Livo, Keith E.; Morath, Laurie C.

    2009-01-01

    On September 17 and 18, 2001, samples of settled dust and airfall debris were collected from 34 sites within a 1-km radius of the WTC collapse site, including a sample from an indoor location unaffected by rainfall, and samples of insulation from two steel beams at Ground Zero. Laboratory spectral and x-ray diffraction analyses of the field samples detected trace levels of serpentine minerals, including chrysotile asbestos, in about two-thirds of the dust samples at concentrations at or below ~1 wt%. One sample of a beam coating material contained up to 20 wt% chrysotile asbestos. Analyses indicate that trace levels of chrysotile were distributed with the dust radially to distances greater than 0.75 km from Ground Zero. The chrysotile content of the dust is variable and may indicate that chrysotile asbestos was not distributed uniformly during the three collapse events.

  2. Spectroscopic analyses of subluminous B stars: observational constraints for the theory of stellar evolution, pulsation, and diffusion

    NASA Astrophysics Data System (ADS)

    Edelmann, Heinz

    2003-06-01

    This thesis deals with quantitative spectroscopic analyses of large samples of subluminous B stars in order to find constraints the theory of stellar evolution, pulsation, and diffusion. Subluminous B stars, also known as subdwarf B (sdB) stars, are very important in several respects: They dominate the population of faint blue stars in high galactic latitudes, and are found both in the field and in globular clusters. Therefore, sdB stars are important to understand the structure and evolution of our galaxy. From the cosmological point of view, they are candidate progenitors of supernovae of type Ia due to their membership in close binary systems. In the context of stellar astrophysics, subdwarf B stars play an important role because several of them are discovered to show non-radial pulsations, which allows to probe their interior by asteroseismology. Last but not least, sdB stars show very peculiar element abundance patterns, probably caused by diffusion processes. Subluminous B stars are generally considered to be core helium-burning stars with extremely thin hydrogen envelopes (< 0.02M) and masses around 0.5M. In the Hertzsprung-Russell diagram they populate a very narrow area which lies on a blue-ward extension of the horizontal branch (HB), the so called "Extreme Horizontal Branch" (EHB). Due to their thin hydrogen-rich envelope, they cannot sustain a hydrogen-burning shell. This means that the sdB stars cannot ascend the asymptotic giant branch after the end of the helium-core burning, but should evolve directly to the white dwarf graveyard. However, according to standard stellar evolution theory, subdwarf B stars should not exist. Their evolution is still unclear and several scenarios are under debate. For all these investigations, knowledge of the stellar parameters (effective temperature, gravity and chemical composition) is very important to verify or discard theoretical models and predictions. Numerous observing runs have been performed mostly by myself

  3. Biochemical, mechanical, and spectroscopic analyses of genetically engineered flax fibers producing bioplastic (poly-beta-hydroxybutyrate).

    PubMed

    Wróbel-Kwiatkowska, Magdalena; Skórkowska-Telichowska, Katarzyna; Dymińska, Lucyna; Maczka, Mirosław; Hanuza, Jerzy; Szopa, Jan

    2009-01-01

    The interest in biofibers has grown in recent years due to their expanding range of applications in fields as diverse as biomedical science and the automotive industry. Their low production costs, biodegradability, physical properties, and perceived eco-friendliness allow for their extensive use as composite components, a role in which they could replace petroleum-based synthetic polymers. We performed biochemical, mechanical, and structural analyses of flax stems and fibers derived from field-grown transgenic flax enriched with PHB (poly-beta-hydroxybutyrate). The analyses of the plant stems revealed an increase in the cellulose content and a decrease in the lignin and pectin contents relative to the control plants. However, the contents of the fibers' major components (cellulose, lignin, pectin) remain unchanged. An FT-IR study confirmed the results of the biochemical analyses of the flax fibers. However, the arrangement of the cellulose polymer in the transgenic fibers differed from that in the control, and a significant increase in the number of hydrogen bonds was detected. The mechanical properties of the transgenic flax stems were significantly improved, reflecting the cellulose content increase. However, the mechanical properties of the fibers did not change in comparison with the control, with the exception of the fibers from transgenic line M13. The generated transgenic flax plants, which produce both components of the flax/PHB composites (i.e., fibers and thermoplastic matrix in the same plant organ) are a source of an attractive and ecologically safe material for industry and medicine. PMID:19572280

  4. Vibrational spectroscopic analyses of unique yellow feather pigments (spheniscins) in penguins

    PubMed Central

    Thomas, Daniel B.; McGoverin, Cushla M.; McGraw, Kevin J.; James, Helen F.; Madden, Odile

    2013-01-01

    Many animals extract, synthesize and refine chemicals for colour display, where a range of compounds and structures can produce a diverse colour palette. Feather colours, for example, span the visible spectrum and mostly result from pigments in five chemical classes (carotenoids, melanins, porphyrins, psittacofulvins and metal oxides). However, the pigment that generates the yellow colour of penguin feathers appears to represent a sixth, poorly characterized class of feather pigments. This pigment class, here termed ‘spheniscin’, is displayed by half of the living penguin genera; the larger and richer colour displays of the pigment are highly attractive. Using Raman and mid-infrared spectroscopies, we analysed yellow feathers from two penguin species (king penguin, Aptenodytes patagonicus; macaroni penguin, Eudyptes chrysolophus) to further characterize spheniscin pigments. The Raman spectrum of spheniscin is distinct from spectra of other feather pigments and exhibits 17 distinctive spectral bands between 300 and 1700 cm−1. Spectral bands from the yellow pigment are assigned to aromatically bound carbon atoms, and to skeletal modes in an aromatic, heterocyclic ring. It has been suggested that the penguin pigment is a pterin compound; Raman spectra from yellow penguin feathers are broadly consistent with previously reported pterin spectra, although we have not matched it to any known compound. Raman spectroscopy can provide a rapid and non-destructive method for surveying the distribution of different classes of feather pigments in the avian family tree, and for correlating the chemistry of spheniscin with compounds analysed elsewhere. We suggest that the sixth class of feather pigments may have evolved in a stem-lineage penguin and endowed modern penguins with a costly plumage trait that appears to be chemically unique among birds. PMID:23516063

  5. Microscopic and Spectroscopic Analyses of Chlorhexidine Tolerance in Delftia acidovorans Biofilms

    PubMed Central

    Rema, Tara; Lawrence, John R.; Dynes, James J.; Hitchcock, Adam P.

    2014-01-01

    The physicochemical responses of Delftia acidovorans biofilms exposed to the commonly used antimicrobial chlorhexidine (CHX) were examined in this study. A CHX-sensitive mutant (MIC, 1.0 μg ml−1) was derived from a CHX-tolerant (MIC, 15.0 μg ml−1) D. acidovorans parent strain using transposon mutagenesis. D. acidovorans mutant (MT51) and wild-type (WT15) strain biofilms were cultivated in flow cells and then treated with CHX at sub-MIC and inhibitory concentrations and examined by confocal laser scanning microscopy (CLSM), scanning transmission X-ray microscopy (STXM), and infrared (IR) spectroscopy. Specific morphological, structural, and chemical compositional differences between the CHX-treated and -untreated biofilms of both strains were observed. Apart from architectural differences, CLSM revealed a negative effect of CHX on biofilm thickness in the CHX-sensitive MT51 biofilms relative to those of the WT15 strain. STXM analyses showed that the WT15 biofilms contained two morphochemical cell variants, whereas only one type was detected in the MT51 biofilms. The cells in the MT51 biofilms bioaccumulated CHX to a similar extent as one of the cell types found in the WT15 biofilms, whereas the other cell type in the WT15 biofilms did not bioaccumulate CHX. STXM and IR spectral analyses revealed that CHX-sensitive MT51 cells accumulated the highest levels of CHX. Pretreating biofilms with EDTA promoted the accumulation of CHX in all cells. Thus, it is suggested that a subpopulation of cells that do not accumulate CHX appear to be responsible for greater CHX resistance in D. acidovorans WT15 biofilm in conjunction with the possible involvement of bacterial membrane stability. PMID:25022584

  6. Combined Quantum Chemical/Raman Spectroscopic Analyses of Li+ Cation Solvation: Cyclic Carbonate Solvents - Ethylene Carbonate and Propylene Earbonate

    SciTech Connect

    Allen, Joshua L.; Borodin, Oleg; Seo, D. M.; Henderson, Wesley A.

    2014-12-01

    Combined computational/Raman spectroscopic analyses of ethylene carbonate (EC) and propylene carbonate (PC) solvation interactions with lithium salts are reported. It is proposed that previously reported Raman analyses of (EC)n-LiX mixtures have utilized faulty assumptions. In the present studies, density functional theory (DFT) calculations have provided corrections in terms of both the scaling factors for the solvent's Raman band intensity variations and information about band overlap. By accounting for these factors, the solvation numbers obtained from two different EC solvent bands are in excellent agreement with one another. The same analysis for PC, however, was found to be quite challenging. Commercially available PC is a racemic mixture of (S)- and (R)-PC isomers. Based upon the quantum chemistry calculations, each of these solvent isomers may exist as multiple conformers due to a low energy barrier for ring inversion, making deconvolution of the Raman bands daunting and inherently prone to significant error. Thus, Raman spectroscopy is able to accurately determine the extent of the EC...Li+ cation solvation interactions using the provided methodology, but a similar analysis of PC...Li+ cation solvation results in a significant underestimation of the actual solvation numbers.

  7. Distinct circular dichroism spectroscopic signatures of polyproline II and unordered secondary structures: Applications in secondary structure analyses

    PubMed Central

    Lopes, Jose L S; Miles, Andrew J; Whitmore, Lee; Wallace, B A

    2014-01-01

    Circular dichroism (CD) spectroscopy is a valuable method for defining canonical secondary structure contents of proteins based on empirically-defined spectroscopic signatures derived from proteins with known three-dimensional structures. Many proteins identified as being “Intrinsically Disordered Proteins” have a significant amount of their structure that is neither sheet, helix, nor turn; this type of structure is often classified by CD as “other”, “random coil”, “unordered”, or “disordered”. However the “other” category can also include polyproline II (PPII)-type structures, whose spectral properties have not been well-distinguished from those of unordered structures. In this study, synchrotron radiation circular dichroism spectroscopy was used to investigate the spectral properties of collagen and polyproline, which both contain PPII-type structures. Their native spectra were compared as representatives of PPII structures. In addition, their spectra before and after treatment with various conditions to produce unfolded or denatured structures were also compared, with the aim of defining the differences between CD spectra of PPII and disordered structures. We conclude that the spectral features of collagen are more appropriate than those of polyproline for use as the representative spectrum for PPII structures present in typical amino acid-containing proteins, and that the single most characteristic spectroscopic feature distinguishing a PPII structure from a disordered structure is the presence of a positive peak around 220nm in the former but not in the latter. These spectra are now available for inclusion in new reference data sets used for CD analyses of the secondary structures of soluble proteins. PMID:25262612

  8. Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates

    NASA Astrophysics Data System (ADS)

    Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

    2015-04-01

    This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out.

  9. Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates.

    PubMed

    Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

    2015-04-01

    This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out. PMID:25646895

  10. Integrated approaches of x-ray absorption spectroscopic and electron microscopic techniques on zinc speciation and characterization in a final sewage sludge product.

    PubMed

    Kim, Bojeong; Levard, Clément; Murayama, Mitsuhiro; Brown, Gordon E; Hochella, Michael F

    2014-05-01

    Integration of complementary techniques can be powerful for the investigation of metal speciation and characterization in complex and heterogeneous environmental samples, such as sewage sludge products. In the present study, we combined analytical transmission electron microscopy (TEM)-based techniques with X-ray absorption spectroscopy (XAS) to identify and characterize nanocrystalline zinc sulfide (ZnS), considered to be the dominant Zn-containing phase in the final stage of sewage sludge material of a full-scale municipal wastewater treatment plant. We also developed sample preparation procedures to preserve the organic and sulfur-rich nature of sewage sludge matrices for microscopic and spectroscopic analyses. Analytical TEM results indicate individual ZnS nanocrystals to be in the size range of 2.5 to 7.5 nm in diameter, forming aggregates of a few hundred nanometers. Observed lattice spacings match sphalerite. The ratio of S to Zn for the ZnS nanocrystals is estimated to be 1.4, suggesting that S is present in excess. The XAS results on the Zn speciation in the bulk sludge material also support the TEM observation that approximately 80% of the total Zn has the local structure of a 3-nm ZnS nanoparticle reference material. Because sewage sludge is frequently used as a soil amendment on agricultural lands, future studies that investigate the oxidative dissolution rate of ZnS nanoparticles as a function of size and aggregation state and the change of Zn speciation during post sludge-processing and soil residency are warranted to help determine the bioavailability of sludge-born Zn in the soil environment. PMID:25602819

  11. Numerical analyses of the sound absorption of cylindrical microperforated panel space absorbers with cores.

    PubMed

    Toyoda, Masahiro; Fujita, Shota; Sakagami, Kimihiro

    2015-12-01

    Microperforated panels (MPPs) are next-generation absorption materials because they can provide wideband sound absorption without fibrous materials and can be composed of diverse materials to meet global environmental demands. The fundamental absorbing mechanism is Helmholtz-resonance absorption due to perforations and an air cavity. MPPs are typically backed by rigid flat walls, but to reduce the restrictions on the MPP absorber properties, one of the authors has proposed MPP space sound absorbers without backing structures, including three-dimensional cylindrical microperforated panel space absorbers (CMSAs). Advantages of MPPs without backing structures are design flexibility and ease of use. Besides, the absorption characteristics of a CMSA with a core, which has a rigid cylindrical core inside the CMSA, have been experimentally tested, but a method to predict the absorption characteristics is necessary to design CMSAs with cores. Herein the two-dimensional combined Helmholtz integral formulation method is employed, and its prediction accuracy is evaluated by comparing the measured and predicted absorption characteristics of a CMSA with a core. Furthermore, a parametric study with regard to the core size is carried out to investigate the transition of the absorbing mechanism. PMID:26723310

  12. The gaseous extent of galaxies and the origin of Lyman-alpha absorption systems: A survey of galaxies in the fields of Hubble Space Telescope spectroscopic target QSOs

    NASA Technical Reports Server (NTRS)

    Lanzetta, Kenneth M.; Bowen, David B.; Tytler, David; Webb, John K.

    1995-01-01

    We present initial results of an imaging and spectroscopic survey of faint galaxies in fields of Hubble Space Telescope (HST) spectroscopic target QSOs. The primary objectives of the survey are (1) to determine the incidence, extent, and covering factor of extended gaseous envelopes of luminous galaxies and (2) to determine the fraction of Ly(alpha) absorption systems that arise in luminous galaxies. The goal of the survey is to identify in each field under construction all objects with apparent r-band magnitudes satisfying r less than 21.5 within angular distances to the QSOs satisfying 0 less thyan 1.3'. The current observations cover six fields and are 37% complete to the goal ofthe survey. These observations identify 46 galaxies at redshifts spanning z = 0.0700-0.5526 and at impact parameters to the QSOs spanning rho = 16.6-346.9/h kpc. Of these galaxies, 11 are coincident in redshift with absorption systems and 21 do not give rise to absorption to within sensitive upper limits. Nine galaxies are coincident in redshift with 'Ly(alpha)-forest' absorption systems that show Ly(alpha) absorption but no corresponding metal-line absorption, and two galaxies are coincident in redshift with C IV absorption systems that show both Ly(alpha) and C IV absorption. Various lines of evidence demonstrate that the coincident galaxies are responsible for the corresponding absorption systems and are not present as the result of chance coincidence or merely spatial correlated with the absorption systems. The most important evidence is that there exists a statistical anti-correlation between Ly(aplha) rest-frame equivalent width and the impact parameter. Each of five galaxies with rho = 70-160/h kpc give rise to Ly(alpha) absorption, and just one of nine galaxies with rho greater than 70-160/h kpc gives rise to Ly(alpha) absorption. At least eight of 23 Ly(alpha) absorption systyems arise in galaxies. On the basis of these results we reach the following conclusions: (1) At z less

  13. Effect of steric hindrance on carbon dioxide absorption into new amine solutions: thermodynamic and spectroscopic verification through solubility and NMR analysis.

    PubMed

    Park, Jung-Yeon; Yoon, Sang Jun; Lee, Huen

    2003-04-15

    Acid gas absorption technology is of great importance in these days for the prevention of global warming and the resulting worldwide climate change. More efficient process design and development for the removal of acid gases has become important, together with the development of new absorbents as one of urgent areas of research in addressing global-warming problems. In the present work, aqueous solutions of 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD), a sterically hindered amine, has been examined as a potential CO2 absorbent and compared with the most commonly used absorbent, monoethanolamine (MEA) solution, through equilibrium solubility measurements and 13C NMR spectroscopic analyses. The solubilities of CO2 in aqueous 10 mass % AHPD solutions were higher than those in aqueous 10 mass % MEA solutions above 4 kPa at 298.15 K, but below 4 kPa, the solubility behavior appeared to be the opposite. The solubility difference between these two solutions increased with the CO2 partial pressures above the crossover pressure. Equilibrated CO2-MEA-H2O and CO2-AHPD-H2O solutions at various CO2 partal pressures ranging from 0.01 to 3000 kPa were analyzed by 13C NMR spectroscopy to provide a more microscopic understanding of the reaction mechanisms in the two solutions. In the CO2-amine-H2O solutions, amine reacted with CO2 to form mainly the protonated amine (AMH+), bicarbonate ion (HCO3-), and carbamate anion (AMCO2-), where the quantitative ratio of bicarbonate ion to carbamate anion strongly influenced the CO2 loading in the amine solutions. A profusion of bicarbonate ions, but a very small amount of carbamate anions, was identified in the CO2-AHPD-H2O solution, whereas a considerable amount of carbamate anions was formed in the CO2-MEA-H2O solution. AHPD contains more hydroxyl groups than nonhindered MEA, and hence, the chemical shifts in its 13C NMR spectra were strongly influenced by the solution pH values. In contrast, MEA appeared to be insensitive to pH. The

  14. Continuous measurements of nitrous oxide, carbon monoxide, methane and carbon dioxide in the surface ocean with novel laser-absorption analysers

    NASA Astrophysics Data System (ADS)

    Kaiser, Jan; Grefe, Imke; Wager, Natalie; Bakker, Dorothee C. E.; Lee, Gareth A.

    2013-04-01

    In recent years, improvements in spectroscopic technology have revolutionised atmospheric trace gas research. In particular, cavity-based optical absorption analysers allow determination of gas concentrations with high frequency, repeatability, reproducibility and long-term stability. These qualities make them particularly suitable for autonomous measurements on voluntary observing ships (VOS). Here, we present results from three of the first deployments of such analysers on research ships, as a first step towards VOS installations. Los Gatos off-axis ICOS (Integrated Cavity Output Spectroscopy) analysers were used to measure nitrous oxide (N2O), carbon monoxide (CO), methane (CH4) and carbon dioxide (CO2) mixing ratios in ocean surface water during research cruises in 2010, 2011 and 2012. The analysers were coupled to an equilibrator fed by the scientific seawater supply in the ship's laboratories. The equilibrator measurements were alternated with regular measurements of marine air and calibrated standard gases. Short-term precision for 10 s-average N2O mole fractions at an acquisition rate of 1 Hz was better than 0.2 nmol mol-1. The same value was achieved for duplicate measurements of a standard gas analysed within 1 hour of each other. The response time to concentration changes in water was 142-203 s, depending on the headspace flow rate. During the first deployment on the AMT20 cruise (Atlantic Meridional Transect, Southampton to Punta Arenas, 12 October to 25 November 2010), we unexpectedly found the subtropical gyres to be slightly undersaturated in N2O, implying that this region acted as a sink for this greenhouse gas. In contrast, the equatorial region was supersaturated and a source of nitrous oxide to the atmosphere. Mean sea-to-air fluxes were overall small and ranged between -1.6 and 0.11 μmol m-2 d-1 (negative fluxes imply an net uptake by the ocean). Despite the good short-term repeatability, significant calibration drift occurred between the six

  15. X-ray absorption spectroscopic studies of the active sites of nickel- and copper-containing metalloproteins

    SciTech Connect

    Tan, G.O.

    1993-06-01

    X-ray absorption spectroscopy (XAS) is a useful tool for obtaining structural and chemical information about the active sites of metalloproteins and metalloenzymes. Information may be obtained from both the edge region and the extended X-ray absorption fine structure (EXAFS) or post-edge region of the K-edge X-ray absorption spectrum of a metal center in a compound. The edge contains information about the valence electronic structure of the atom that absorbs the X-rays. It is possible in some systems to infer the redox state of the metal atom in question, as well as the geometry and nature of ligands connected to it, from the features in the edge in a straightforward manner. The EXAFS modulations, being produced by the backscattering of the ejected photoelectron from the atoms surrounding the metal atom, provide, when analyzed, information about the number and type of neighbouring atoms, and the distances at which they occur. In this thesis, analysis of both the edge and EXAFS regions has been used to gain information about the active sites of various metalloproteins. The metalloproteins studied were plastocyanin (Pc), laccase and nickel carbon monoxide dehydrogenase (Ni CODH). Studies of Cu(I)-imidazole compounds, related to the protein hemocyanin, are also reported here.

  16. X-ray absorption fine structure spectroscopic determination of plutonium speciation at the Rocky Flats environmental technology

    SciTech Connect

    Lezama-pacheco, Juan S; Conradson, Steven D; Clark, David L

    2008-01-01

    X-ray Absorption Fine Structure spectroscopy was used to probe the speciation of the ppm level Pu in thirteen soil and concrete samples from the Rocky Flats Environmental Technology Site in support of the site remediation effort that has been successfully completed since these measurements. In addition to X-ray Absorption Near Edge Spectra, two of the samples yielded Extended X-ray Absorption Fine Structure spectra that could be analyzed by curve-fits. Most of these spectra exhibited features consistent with PU(IV), and more specificaJly, PuO{sub 2+x}-type speciation. Two were ambiguous, possibly indicating that Pu that was originally present in a different form was transforming into PuO{sub 2+x}, and one was interpreted as demonstrating the presence of an unusual Pu(VI) compound, consistent with its source being spills from a PUREX purification line onto a concrete floor and the resultant extreme conditions. These experimental results therefore validated models that predicted that insoluble PuO{sub 2+x} would be the most stable form of Pu in equilibrium with air and water even when the source terms were most likely Pu metal with organic compounds or a Pu fire. A corollary of these models' predictions and other in situ observations is therefore that the minimal transport of Pu that occurred on the site was via the resuspension and mobilization of colloidal particles. Under these conditions, the small amounts of diffusely distributed Pu that were left on the site after its remediation pose only a negligible hazard.

  17. Characterisation of bhringaraj and guduchi herb by ICP-MS analysis, optical absorption, infrared and EPR spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Reddy, S. Lakshmi; Fayazuddin, Md.; Reddy, N. C. G.; Ahmad, Adeel; Reddy, G. Siva; Rao, P. Sambasiva; Reddy, B. Jagannatha; Frost, R. L.

    2008-11-01

    Leaves of bhringaraj and guduchi herb of Kadapa district of Andhra Pradesh, India, are dried and powdered. ICP-MS analysis of samples indicates that copper is present in both the samples. An EPR study of guduchi sample also confirms the presence of Fe(III) whereas Eclipta alba confirms the presence of Fe(III), Mn(II) and Cu(II). Optical absorption spectrum of guduchi indicates that Cu(II) is present in rhombically distorted octahedral environment. NIR and IR results are due to carbonate fundamentals.

  18. Spectroscopic and DFT study of solvent effects on the electronic absorption spectra of sulfamethoxazole in neat and binary solvent mixtures

    NASA Astrophysics Data System (ADS)

    Almandoz, M. C.; Sancho, M. I.; Blanco, S. E.

    2014-01-01

    The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π*). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture.

  19. Tiny peaks vs mega backgrounds: a general spectroscopic method with applications in resonant Raman scattering and atmospheric absorptions.

    PubMed

    Auguié, Baptiste; Reigue, Antoine; Le Ru, Eric C; Etchegoin, Pablo G

    2012-09-18

    A simple method using standard spectrometers with charge-coupled device (CCD) detectors is described to routinely measure background-corrected spectra in situations where the signal is composed of weak spectral features (such as Raman peaks or absorption lines) engulfed in a much stronger (by as much as ∼10(5)) broad background. The principle of the method is to subtract the dominant fixed-structure noise and obtain a shot-noise limited spectrum. The final noise level can therefore be reduced as desired by sufficient integration time. The method requires multiple shifts of the diffraction gratings to extract the pixel-dependent noise structure, which is then used as a flat-field correction. An original peak-retrieval procedure is proposed, demonstrating accurate determination of peak lineshapes and linewidths and robustness on practical examples where conventional methods would not be applicable. Examples are discussed to illustrate the potential of the technique to perform routine resonant Raman measurements of fluorescent dyes with high quantum yield, using conventional Raman systems. The method can equally be applied to other situations where small features are masked by a broad overwhelming background. An explicit example is given with the measurement of weak absorption lines in atmospheric gases. PMID:22894881

  20. PROBING THE FERMI BUBBLES IN ULTRAVIOLET ABSORPTION: A SPECTROSCOPIC SIGNATURE OF THE MILKY WAY'S BICONICAL NUCLEAR OUTFLOW

    SciTech Connect

    Fox, Andrew J.; Bordoloi, Rongmon; Hernandez, Svea; Tumlinson, Jason; Savage, Blair D.; Wakker, Bart P.; Lockman, Felix J.; Bland-Hawthorn, Joss; Kim, Tae-Sun; Benjamin, Robert A.

    2015-01-20

    Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (ℓ, b = 10.°4, +11.°2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v {sub LSR} = –235 and +250 km s{sup –1}, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of ≳900 km s{sup –1} and a full opening angle of ≈110° (matching the X-ray bicone). This indicates Galactic center activity over the last ≈2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles.

  1. Spectroscopic determination of leaf biochemistry using band-depth analysis of absorption features and stepwise multiple linear regression

    USGS Publications Warehouse

    Kokaly, R.F.; Clark, R.N.

    1999-01-01

    We develop a new method for estimating the biochemistry of plant material using spectroscopy. Normalized band depths calculated from the continuum-removed reflectance spectra of dried and ground leaves were used to estimate their concentrations of nitrogen, lignin, and cellulose. Stepwise multiple linear regression was used to select wavelengths in the broad absorption features centered at 1.73 ??m, 2.10 ??m, and 2.30 ??m that were highly correlated with the chemistry of samples from eastern U.S. forests. Band depths of absorption features at these wavelengths were found to also be highly correlated with the chemistry of four other sites. A subset of data from the eastern U.S. forest sites was used to derive linear equations that were applied to the remaining data to successfully estimate their nitrogen, lignin, and cellulose concentrations. Correlations were highest for nitrogen (R2 from 0.75 to 0.94). The consistent results indicate the possibility of establishing a single equation capable of estimating the chemical concentrations in a wide variety of species from the reflectance spectra of dried leaves. The extension of this method to remote sensing was investigated. The effects of leaf water content, sensor signal-to-noise and bandpass, atmospheric effects, and background soil exposure were examined. Leaf water was found to be the greatest challenge to extending this empirical method to the analysis of fresh whole leaves and complete vegetation canopies. The influence of leaf water on reflectance spectra must be removed to within 10%. Other effects were reduced by continuum removal and normalization of band depths. If the effects of leaf water can be compensated for, it might be possible to extend this method to remote sensing data acquired by imaging spectrometers to give estimates of nitrogen, lignin, and cellulose concentrations over large areas for use in ecosystem studies.We develop a new method for estimating the biochemistry of plant material using

  2. Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow

    NASA Astrophysics Data System (ADS)

    Fox, Andrew J.; Bordoloi, Rongmon; Savage, Blair D.; Lockman, Felix J.; Jenkins, Edward B.; Wakker, Bart P.; Bland-Hawthorn, Joss; Hernandez, Svea; Kim, Tae-Sun; Benjamin, Robert A.; Bowen, David V.; Tumlinson, Jason

    2015-01-01

    Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (l, b = 10.°4, +11.°2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v LSR = -235 and +250 km s-1, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of gsim900 km s-1 and a full opening angle of ≈110° (matching the X-ray bicone). This indicates Galactic center activity over the last ≈2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles. Based on observations taken under program 13448 of the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, and under program 14B-299 of the NRAO Green Bank Telescope, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  3. The joined use of n.i. spectroscopic analyses FTIR, Raman, visible reflectance spectrometry and EDXRF to study drawings and illuminated manuscripts

    NASA Astrophysics Data System (ADS)

    Bruni, S.; Caglio, S.; Guglielmi, V.; Poldi, G.

    2008-07-01

    Some art objects being small and very precious prevents conservators and conservation scientists from whatever kind of sampling, so that only completely non-invasive (n.i.) studies are permitted. Besides, also moving the object is sometimes forbidden: this happens for jewels as well as for manuscripts, illuminated codices, drawings and paintings. Some important physical n.i. analyses, such as PIXE and PIGE, therefore cannot be used in many cases. With these limitations, only imaging techniques in X, UV, Visible and IR bands, and a few spectroscopic methods that can be carried out with portable instruments can be applied, i.e. molecular spectroscopies like Fourier transform infrared (FTIR), Raman, UV visible and near IR reflectance spectrometry (UV-Vis-NIR RS) and atomic spectroscopy like energy dispersive X-ray fluorescence (EDXRF). The use of only one or two of these techniques is usually far from giving all the information required to achieve a full characterization of materials used by the artist or during restorations, and to understand some conservative problems of the object. On the contrary, a joined use of n.i. analyses can supply a larger set of data, allowing for cross checks. With this aim we show a fully integrated spectroscopic approach to polychrome objects, and, in particular, to drawings and illuminated manuscripts, using portable instruments, specifically μ-FTIR, μ-Raman, Vis-RS and EDXRF, where also the Raman signal does not suffer fluorescence caused by varnish coating and from binder. We propose the joined use of all these four physical analyses to characterize materials support, pigments, dyes, binders, etc. on a complex case: a painted and drawn parchment of the late 15th century, or the beginning of the 16th, partly attributed to Andrea Mantegna. The collected spectroscopic data have been compared to proper spectral databases, some of which specifically realized in our laboratories. Also, mixtures of pigments and their stratigraphical

  4. Local structure and speciation of platinum in fresh and road-aged North American sourced vehicle emissions catalysts: an X-ray absorption spectroscopic study.

    PubMed

    Ash, Peter W; Boyd, David A; Hyde, Timothy I; Keating, Jonathan L; Randlshofer, Gabriele; Rothenbacher, Klaus; Sankar, Gopinathan; Schauer, James J; Shafer, Martin M; Toner, Brandy M

    2014-04-01

    Given emerging concerns about the bioavailability and toxicity of anthropogenic platinum compounds emitted into the environment from sources including vehicle emission catalysts (VEC), the platinum species present in selected North American sourced fresh and road-aged VEC were determined by Pt and Cl X-ray absorption spectroscopy. Detailed analysis of the Extended X-ray Absorption Fine Structure at the Pt L3 and L2 edges of the solid phase catalysts revealed mainly oxidic species in the fresh catalysts and metallic components dominant in the road-aged catalysts. In addition, some bimetallic components (Pt-Ni, Pt-Pd, Pt-Rh) were observed in the road-aged catalysts from supporting Ni-, Pd-, and Rh-K edge XAS studies. These detailed analyses allow for the significant conclusion that this study did not find any evidence for the presence of chloroplatinate species in the investigated solid phase of a Three Way Catalyst or Diesel Oxidation Catalysts. PMID:24568168

  5. Monitoring and characterization of compost obtained from household waste and pine sawdust in a facultative reactor by conventional and spectroscopic analyses.

    PubMed

    de Campos, Sandro Xavier; Resseti, Rolan Roney; Zittel, Rosimara

    2014-12-01

    This study proposes a new facultative reactor configuration for the treatment of organic household waste and pine sawdust. The process was monitored and the compost characterized by conventional (temperature, moisture, pH, ash content and ratio C/N) conjugated with spectroscopic analyses (ultraviolet (UV)/visible (Vis) and infrared (IR)) and germination index. The spectroscopy results revealed enrichment of carbon-carbon unsaturation structures and a degradation of the aliphatic structures. The results showed that stability of the final product was reached after 90 days and that the compost obtained presents substantial richness of stabilized organic matter and an absence of toxicity, so it may be considered as an organic fertilizer. Finally, this study led to the conclusion that the reactor proposed can be a promising technology for the management of organic household waste and sawdust. PMID:25106532

  6. Infrared and Raman spectroscopic analyses and theoretical computation of 4-butyl-1-(4-hydroxyphenyl)-2-phenyl-3,5-pyrazolidinedione

    NASA Astrophysics Data System (ADS)

    Binil, P. S.; Mary, Y. Sheena; Varghese, Hema Tresa; Panicker, C. Yohannan; Anoop, M. R.; Manojkumar, T. K.

    Infrared and Raman spectroscopic analyses were carried out on 4-butyl-1-(4-hydroxyphenyl)-2-phenyl-3,5-pyrazolidinedione. The interpretation of the spectra was aided by DFT calculation of the molecule. The vibrational wavenumbers were examined theoretically using the Gaussian03 set of quantum chemistry codes and the normal modes were assigned by potential energy distribution calculations. A computation of the first hyperpolarizability of the compound indicates that the compound may be a good candidate as a NLO material. Optimized geometrical parameters are in agreement with the reported XRD results. The RMS error of the observed Raman bands and IR bands are found to be 35.09 and 39.57 for HF method and 14.31 and 17.17 for DFT method. The predicted infrared intensities and Raman activities are reported.

  7. The chemical environment of iron in mineral fibres. A combined X-ray absorption and Mössbauer spectroscopic study.

    PubMed

    Pollastri, Simone; D'Acapito, Francesco; Trapananti, Angela; Colantoni, Ivan; Andreozzi, Giovanni B; Gualtieri, Alessandro F

    2015-11-15

    Although asbestos represents today one of the most harmful contaminant on Earth, in 72% of the countries worldwide only amphiboles are banned while controlled use of chrysotile is allowed. Uncertainty on the potential toxicity of chrysotile is due to the fact that the mechanisms by which mineral fibres induces cyto- and geno-toxic damage are still unclear. We have recently started a long term project aimed at the systematic investigation of the crystal-chemistry, bio-interaction and toxicity of the mineral fibres. This work presents a systematic structural investigation of iron in asbestos and erionite (considered the most relevant mineral fibres of social and/or economic-industrial importance) using synchrotron X-ray absorption and Mössbauer spectroscopy. In all investigated mineral fibres, iron in the bulk structure is found in octahedral sites and can be made available at the surface via fibre dissolution. We postulate that the amount of hydroxyl radicals released by the fibers depends, among other factors, upon their dissolution rate; in relation to this, a ranking of ability of asbestos fibres to generate hydroxyl radicals, resulting from available surface iron, is advanced: amosite > crocidolite ≈ chrysotile > anthophyllite > tremolite. Erionite, with a fairly high toxicity potential, contains only octahedrally coordinated Fe(3+). Although it needs further experimental evidence, such available surface iron may be present as oxide nanoparticles coating and can be a direct cause of generation of hydroxyl radicals when such coating dissolves. PMID:26073382

  8. X-ray absorption spectroscopic evidence for the complexation of Hg(II) by reduced sulfur in soil humic substances

    SciTech Connect

    Xia, K.; Skyllberg, U.L.; Bleam, W.F.; Helmke, P.A.; Bloom, P.R.; Nater, E.A.

    1999-01-15

    Analysis of Hg(II) complexed by a soil humic acid (HA) using synchrotron-based X-ray absorption spectroscopy (XAS) revealed the importance of reduces sulfur functional groups (thiol (R-SH) and disulfide (R-SS-R)/disulfane (R-SSH)) in humic substances in the complexation of Hg(II). A two-coordinate binding environment with one oxygen atom and one sulfur atom at distances of 2.02 and 2.38 {angstrom}, respectively, was found in the first coordination shell of Hg(II) complexed by humic acid. Model calculations show that a second coordination sphere could contain one carbon atom and a second sulfur atom at 2.78 and 2.93 {angstrom}, respectively. This suggests that in addition to thiol S, disulfide/disulfane S may be involved with the complexation of Hg(II) in soil organic matter. The appearance of carbon atom in the second coordination shell suggests that one O-containing ligand such as carboxyl and phenol ligands rather than H{sub 2}O molecule is bound to the Hg(II). The involvement of oxygen ligand in addition to the reduced S ligands in the complexation of Hg(II) is due to the low density of reduced S ligands in humic substances. The XAS results from this experiment provided direct molecular level evidence for the preference of reduced S functional groups over oxygen ligands by Hg(II) in the complexation with humic substances.

  9. Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of fluoroquinolone antibiotics using ammonium reineckate ion-pair complex formation

    NASA Astrophysics Data System (ADS)

    Ragab, Gamal H.; Amin, Alaa S.

    2004-03-01

    Three accurate, rapid and simple atomic absorption spectrometric, conductometric and colorimetric methods were developed for the determination of norfloxacin (NRF), ciprofloxacin (CIP), ofloxacin (OFL) and enrofloxacin (ENF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at λmax 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone in the range 5.0-65, 4.0-48, 5.0-56 and 6.0-72 μg ml -1 of NRF, CPF, OFL and ENF, respectively. The optimizations of various experimental conditions were described. The results obtained showed good recoveries of 99.15±1.15, 99.30±1.40, 99.60±1.50, and 99.00±1.25% with relative standard deviations of 0.81, 1.06, 0.97, and 0.69% for NRF, CPF, OFL, and ENF, respectively. Applications of the proposed methods to representative pharmaceutical formulations are successfully presented.

  10. An x-ray absorption spectroscopic study of the electronic structure and bonding of rare-earth orthoferrites.

    PubMed

    Hayes, J R; Grosvenor, A P

    2011-11-23

    Rare-earth orthoferrites, REFeO₃ (RE D rare earth; Y), are tremendously adaptable compounds that are being investigated for use in a wide variety of applications including gas sensors, vehicle catalytic converters, and solid-oxide fuel cells. They also exhibit interesting magnetic properties such as high-temperature antiferromagnetism, making them useful for data storage applications. The compounds adopt a distorted perovskite-type structure where the tilt angle of the octahedra increases (Fe-O-Fe bond angle decreases) as the size of the rare-earth atom decreases. Despite intensive study of the physical properties of these compounds, very few studies have investigated how the bonding and electronic structure of these systems change with substitution of the RE. X-ray absorption near-edge spectroscopy (XANES) is a technique well-suited for such a study, and, in view of this, Fe L-, Fe K- and O K-edge spectra from a series of REFeO₃ compounds (RE D La, Pr, Nd, Sm, Eu, Gd, Ho, Yb, Y) have been collected, and are presented here. Fe L-edge spectra show that Fe is octahedrally coordinated and that the Fe-centered octahedra do not appear to distort with changes in the identity of the RE. The Fe K-edge spectra contain an intersite hybrid peak, which is an ill-studied feature that is attributed to non-local transitions of 1s electrons to 3d states on the next-nearest-neighbor atom that are hybridized with 4p states on the absorbing atom through O 2p states. In this study, it is shown that the intensity of this feature is strongly dependent on the Fe-O-Fe bond angle; the lower the Fe-O-Fe bond angle, the less intense the intersite hybrid peak is. PMID:22056809

  11. An x-ray absorption spectroscopic study of the electronic structure and bonding of rare-earth orthoferrites

    SciTech Connect

    Hayes, J.R.; Grosvenor, A.P.

    2011-11-07

    Rare-earth orthoferrites, REFeO{sub 3} (RE=rare earth; Y), are tremendously adaptable compounds that are being investigated for use in a wide variety of applications including gas sensors, vehicle catalytic converters, and solid-oxide fuel cells. They also exhibit interesting magnetic properties such as high-temperature antiferromagnetism, making them useful for data storage applications. The compounds adopt a distorted perovskite-type structure where the tilt angle of the octahedra increases (Fe-O-Fe bond angle decreases) as the size of the rare-earth atom decreases. Despite intensive study of the physical properties of these compounds, very few studies have investigated how the bonding and electronic structure of these systems change with substitution of the RE. X-ray absorption near-edge spectroscopy (XANES) is a technique well-suited for such a study, and, in view of this, Fe L-, Fe K- and O K-edge spectra from a series of REFeO{sub 3} compounds (RE=La, Pr, Nd, Sm, Eu, Gd, Ho, Yb, Y) have been collected, and are presented here. Fe L-edge spectra show that Fe is octahedrally coordinated and that the Fe-centered octahedra do not appear to distort with changes in the identity of the RE. The Fe K-edge spectra contain an intersite hybrid peak, which is an ill-studied feature that is attributed to non-local transitions of 1s electrons to 3d states on the next-nearest-neighbor atom that are hybridized with 4p states on the absorbing atom through O 2p states. In this study, it is shown that the intensity of this feature is strongly dependent on the Fe-O-Fe bond angle; the lower the Fe-O-Fe bond angle, the less intense the intersite hybrid peak is.

  12. An x-ray absorption spectroscopic study of the electronic structure and bonding of rare-earth orthoferrites

    NASA Astrophysics Data System (ADS)

    Hayes, J. R.; Grosvenor, A. P.

    2011-11-01

    Rare-earth orthoferrites, REFeO3 (RE=rare earth; Y), are tremendously adaptable compounds that are being investigated for use in a wide variety of applications including gas sensors, vehicle catalytic converters, and solid-oxide fuel cells. They also exhibit interesting magnetic properties such as high-temperature antiferromagnetism, making them useful for data storage applications. The compounds adopt a distorted perovskite-type structure where the tilt angle of the octahedra increases (Fe-O-Fe bond angle decreases) as the size of the rare-earth atom decreases. Despite intensive study of the physical properties of these compounds, very few studies have investigated how the bonding and electronic structure of these systems change with substitution of the RE. X-ray absorption near-edge spectroscopy (XANES) is a technique well-suited for such a study, and, in view of this, Fe L-, Fe K- and O K-edge spectra from a series of REFeO3 compounds (RE=La, Pr, Nd, Sm, Eu, Gd, Ho, Yb, Y) have been collected, and are presented here. Fe L-edge spectra show that Fe is octahedrally coordinated and that the Fe-centered octahedra do not appear to distort with changes in the identity of the RE. The Fe K-edge spectra contain an intersite hybrid peak, which is an ill-studied feature that is attributed to non-local transitions of 1s electrons to 3d states on the next-nearest-neighbor atom that are hybridized with 4p states on the absorbing atom through O 2p states. In this study, it is shown that the intensity of this feature is strongly dependent on the Fe-O-Fe bond angle; the lower the Fe-O-Fe bond angle, the less intense the intersite hybrid peak is.

  13. Spectroscopic Analyses of the "Blue Hook" Stars in Omega Centauri: A Test of the Late Hot Flasher Scenario

    NASA Technical Reports Server (NTRS)

    Moehler, S.; Sweigart, Allan V.; Landsman, W. B.; Dreizler, S.; Rabin, Douglas M. (Technical Monitor)

    2002-01-01

    (Omega) Cen contains the largest population of very hot horizontal branch (HB) stars known in a globular cluster. Recent UV observations (Whitney et al. 1998; D'Cruz et al. 2000) show a significant population of hot stars below the zero-age horizontal branch ("blue hook" stars), which cannot be explained by canonical stellar evolution. Stars which suffer unusually large mass loss on the red giant branch and thus experience the helium core flash while descending the white dwarf cooling curve could populate this region. Theory predicts that these "late hot flashers" should show higher temperatures than the hottest canonical HB stars and should have helium- and carbon-rich atmospheres. We obtained and analysed medium resolution spectra of a sample of blue hook stars to derive their atmospheric parameters. The blue hook stars are indeed both hotter (T(sub eff)>35,000 K) and more helium-rich than classical extreme HB stars. In addition we find indications for a large enhancement of the carbon abundance relative to the cluster abundance.

  14. Innovative tribometer for in situ spectroscopic analyses of wear mechanisms and phase transformation in ceramic femoral heads.

    PubMed

    Puppulin, Leonardo; Leto, Andrea; Wenliang, Zhu; Sugano, Nobuhiko; Pezzotti, Giuseppe

    2014-03-01

    The literature on tribological assessments of artificial hip joints usually focuses on correlations between joint composition, size, and specific wear rates, but conspicuously ignores the physical aspects behind the occurrence of degradation mechanisms of friction and wear. Surface degradation in artificial joints occurs because of increases in temperature and local exacerbation of contact stresses inside the moving contact as a consequence of physical and chemical modifications of the sliding surfaces. This article reports about the development of a new pin-on-ball spectroscopy-assisted tribometer device that enables investigating also physical rather than merely engineering aspects of wear processes using in situ Raman and fluorescence techniques. This innovative tribometer is designed to bring about, in addition to conventional tribological parameters, also information of temperature, stress and phase transformations in the femoral heads as received from the manufacturer. Raman and fluorescence spectra at the point of sliding contact are recorded durilng reciprocating hard-on-hard dry-sliding tests. Preliminary results were collected on two different commercially available ceramic-on-ceramic hip joint bearing couples, made of monolithic alumina and alumina-zirconia composites. Although the composite couple showed direct evidence of tetragonal-to-monoclinic phase transformation, which enhanced the coefficient of friction, the specific wear rate was significantly lower than that of the monolithic one (i.e., by a factor 2.63 and 4.48 on the pin and head side, respectively). In situ collected data compared to ex situ analyses elucidated the surface degradation processes and clarified the origin for the higher wear resistance of the composite as compared to the monolithic couple. PMID:23453272

  15. Lower Extremity Energy Absorption and Biomechanics During Landing, Part II: Frontal-Plane Energy Analyses and Interplanar Relationships

    PubMed Central

    Norcross, Marc F.; Lewek, Michael D.; Padua, Darin A.; Shultz, Sandra J.; Weinhold, Paul S.; Blackburn, J. Troy

    2013-01-01

    Context: Greater sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing is consistent with sagittal-plane biomechanics that likely increase anterior cruciate ligament (ACL) loading, but it does not appear to influence frontal-plane biomechanics. We do not know whether frontal-plane INI EA is related to high-risk frontal-plane biomechanics. Objective: To compare biomechanics among INI EA groups, determine if women are represented more in the high group, and evaluate interplanar INI EA relationships. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: Participants included 82 (41 men, 41 women; age = 21.0 ± 2.4 years, height = 1.74 ± 0.10 m, mass = 70.3 ± 16.1 kg) healthy, physically active volunteers. Intervention(s): We assessed landing biomechanics with an electromagnetic motion-capture system and force plate. Main Outcome Measure(s): We calculated frontal- and sagittal-plane total, hip, knee, and ankle INI EA. Total frontal-plane INI EA was used to create high, moderate, and low tertiles. Frontal-plane knee and hip kinematics, peak vertical and posterior ground reaction forces, and peak internal knee-varus moment (pKVM) were identified and compared across groups using 1-way analyses of variance. We used a χ2 analysis to evaluate male and female allocation to INI EA groups. We used simple, bivariate Pearson product moment correlations to assess interplanar INI EA relationships. Results: The high–INI EA group exhibited greater knee valgus at ground contact, hip adduction at pKVM, and peak hip adduction than the low–INI EA group (P < .05) and greater peak knee valgus, pKVM, and knee valgus at pKVM than the moderate– (P < .05) and low– (P < .05) INI EA groups. Women were more likely than men to be in the high–INI EA group (χ2 = 4.909, P = .03). Sagittal-plane knee and frontal-plane hip INI EA (r = 0.301, P = .006) and sagittal-plane and frontal-plane ankle INI EA were

  16. Compressed shell conditions extracted from spectroscopic analysis of Ti K-shell absorption spectra with evaluation of line self-emission

    SciTech Connect

    Johns, H. M.; Mancini, R. C.; Hakel, P.; Nagayama, T.; Smalyuk, V. A.; Regan, S. P.; Delettrez, J.

    2014-08-15

    Ti-doped tracer layers embedded in the shell at varying distances from the fuel-shell interface serve as a spectroscopic diagnostic for direct-drive experiments conducted at OMEGA. Detailed modeling of Ti K-shell absorption spectra produced in the tracer layer considers n = 1–2 transitions in F- through Li-like Ti ions in the 4400–4800 eV range, both including and excluding line self-emission. Testing the model on synthetic spectra generated from 1-D LILAC hydrodynamic simulations reveals that the model including self-emission best reproduces the simulation, while the model excluding self-emission overestimates electron temperature T{sub e} and density N{sub e} to a higher degree for layers closer to the core. The prediction of the simulation that the magnitude of T{sub e} and duration of Ti absorption will be strongly tied to the distance of the layer from the core is consistent with the idea that regions of the shell close to the core are more significantly heated by thermal transport out of the hot dense core, but more distant regions are less affected by it. The simulation predicts more time variation in the observed T{sub e}, N{sub e} conditions in the compressed shell than is observed in the experiment, analysis of which reveals conditions remain in the range T{sub e} = 400–600 eV and N{sub e} = 3.0–10.0 × 10{sup 24} cm{sup −3} for all but the most distant Ti-doped layer, with error bars ∼5% T{sub e} value and ∼10% N{sub e} on average. The T{sub e}, N{sub e} conditions of the simulation lead to a greater degree of ionization for zones close to the core than occurs experimentally, and less ionization for zones far from the core.

  17. X-Ray Absorption Spectroscopic And Theoretical Studies on (L)(2)[Cu-2(S-2)N](2+) Complexes: Disulfide Versus Disulfide(Center Dot 1-) Bonding

    SciTech Connect

    Sarangi, R.; York, J.T.; Helton, M.E.; Fujisawa, K.; Karlin, K.D.; Tolman, W.B.; Hodgson, K.O.; Hedman, B.; Solomon, E.I.; /Stanford U., Chem. Dept. /SLAC, SSRL /Minnesota U. /Johns Hopkins U. /Tsukuba U.

    2009-04-30

    Cu K-, Cu L-, and S K-edge X-ray absorption spectroscopic (XAS) data have been combined with density functional theory (DFT) calculations on [{l_brace}(TMPA)Cu{r_brace}{sub 2}S{sub 2}](ClO{sub 4}){sub 2} (1), [{l_brace}Cu[HB(3,5-Pr{sub 2}{sup i}pz){sub 3}]{r_brace}{sub 2}(S{sub 2})] (2), and [{l_brace}(TMEDA)Cu{r_brace}{sub 2}(S{sub 2}){sub 2}](OTf){sub 2} (3) to obtain a quantitative description of their ground state wavefunctions. The Cu L-edge intensities give 63 and 37% Cu d-character in the ground state of 1 and 2, respectively, whereas the S K-pre-edge intensities reflect 20 and 48% S character in their ground states, respetively. These data indicate a more than 2-fold increase in the total disulfide bonding character in 2 relative to 1. The increase in the number of Cu?S bonds in 2 ({mu}-{eta}{sup 2}:{eta}{sup 2} S{sub 2}{sup 2-} bridge) compared to 1 ({mu}-{eta}{sup 1}:{eta}{sup 1} S{sub 2}{sup 2-} bridge) dominantly determines the large increase in covalency and Cu-disulfide bond strength in 2. Cu K- and L- and S K-pre-edge energy positions directly demonstrate the Cu{sup II}/(S{sub 2}{sup -}){sub 2} nature of 3. The two disulfide({center_dot}1?)'s in 3 undergo strong bonding interactions that destabilize the resultant filled antibonding {pi}* orbitals of the (S{sub 2}{sup -}){sub 2} fragment relative to the Cu 3d levels. This leads to an inverted bonding scheme in 3 with dominantly ligand-based holes in its ground state, consistent with its description as a dicopper(II)-bis-disulfide({center_dot}1?) complex.

  18. X-ray absorption spectroscopic characterization of the diferric-peroxo intermediate of human deoxyhypusine hydroxylase in the presence of its substrate eIF5a.

    PubMed

    Jasniewski, Andrew J; Engstrom, Lisa M; Vu, Van V; Park, Myung Hee; Que, Lawrence

    2016-09-01

    Human deoxyhypusine hydroxylase (hDOHH) is an enzyme that is involved in the critical post-translational modification of the eukaryotic translation initiation factor 5A (eIF5A). Following the conversion of a lysine residue on eIF5A to deoxyhypusine (Dhp) by deoxyhypusine synthase, hDOHH hydroxylates Dhp to yield the unusual amino acid residue hypusine (Hpu), a modification that is essential for eIF5A to promote peptide synthesis at the ribosome, among other functions. Purification of hDOHH overexpressed in E. coli affords enzyme that is blue in color, a feature that has been associated with the presence of a peroxo-bridged diiron(III) active site. To gain further insight into the nature of the diiron site and how it may change as hDOHH goes through the catalytic cycle, we have conducted X-ray absorption spectroscopic studies of hDOHH on five samples that represent different species along its reaction pathway. Structural analysis of each species has been carried out, starting with the reduced diferrous state, proceeding through its O2 adduct, and ending with a diferric decay product. Our results show that the Fe⋯Fe distances found for the five samples fall within a narrow range of 3.4-3.5 Å, suggesting that hDOHH has a fairly constrained active site. This pattern differs significantly from what has been associated with canonical dioxygen activating nonheme diiron enzymes, such as soluble methane monooxygenase and Class 1A ribonucleotide reductases, for which the Fe⋯Fe distance can change by as much as 1 Å during the redox cycle. These results suggest that the O2 activation mechanism for hDOHH deviates somewhat from that associated with the canonical nonheme diiron enzymes, opening the door to new mechanistic possibilities for this intriguing family of enzymes. PMID:27380180

  19. Electrochemical Kinetics and X-ray Absorption Spectroscopic Investigations of Oxygen Reduction on Chalcogen-Modified Ruthenium Catalysts in Alkaline Media

    SciTech Connect

    N Ramaswamy; R Allen; S Mukerjee; Y

    2011-12-31

    The oxygen reduction reaction (ORR) in alkaline media has been investigated on chalcogen-modified ruthenium nanoparticles (Ru/C, Se/Ru/C, Se/RuMo/C, S/Ru/C, S/RuMo/C) synthesized in-house via aqueous routes. In acidic medium, it is well known that modification by a chalcogen prevents the oxidation of the underlying transition-metal (Ru) surface, thereby promoting direct molecular O{sub 2} adsorption on the Ru metal. On an unmodified Ru catalyst in alkaline media, the surface oxides on Ru mediate the 2e{sup -} reduction of molecular O{sub 2} to a stable peroxide anion (HO{sub 2}{sup -}) intermediate via an outer-sphere electron-transfer mechanism. This increases the activity of HO{sub 2}{sup -} near the electrode surface and decreases the overpotential for ORR by effectively carrying out the reduction of HO{sub 2}{sup -} to OH{sup -} at the oxide-free ruthenium metal site. An increase in ORR activity of Ru is observed by modification with a chalcogen; however, the increase is not as significant as observed in acidic media. Ternary additives, such as Mo, were found to significantly improve the stability of the chalcogen-modified catalysts. Detailed investigations of the ORR activity of this class of catalyst have been carried out in alkaline media along with comparisons to acidic media wherever necessary. A combination of electrochemical and X-ray absorption spectroscopic (EXAFS, XANES, {Delta}{mu}) studies has been performed in order to understand the structure/property relationships of these catalysts within the context of ORR in alkaline electrolytes.

  20. Synthesis, spectroscopic studies, thermal analyses, biological activity of tridentate coordinated transition metal complexes of bi(pyridyl-2-ylmethyl)amine]ligand

    NASA Astrophysics Data System (ADS)

    Abd El-Halim, Hanan F.; Mohamed, Gehad G.

    2016-01-01

    A new tridentate acyclic pincer ligand, [bi(pyridin-2-methyl)amine] (bpma, HL), was synthesized and reacted to form complexes with copper(II), nickel(II), iron(II), cobalt(II) and zinc(II) ions. Both the ligand and its complexes were characterized using elemental analysis, molar conductance, infrared, 1H-NMR-spectroscopy, mass and thermal analyses. According to the spectroscopic data, all of the complexes share the same coordination environment around the metal atoms, consisting two nitrogen-pyridine entities, one nitrogen-methylamine entity, one/two water molecules and/or one/two chloride or bromide ions. Complexes also showed molar conductivity according to the presence of two halide anions outer the coordination sphere except Co(II) and Zn(II) complexes are non electrolytes. Analysis indicates that the metal ions have trigonal bipyramidal structure. Cu(II), Ni(II), Fe(II), Co(II), and Zn(II) metal complexes were screened for their antibacterial activity against Bacillus subtilis, Staphylococcus aureus (G+) and Escherichia coli, and Pseudomonas aeruginosa (G-) bacteria. They showed remarkable antimicrobial activity.

  1. Molecular spectroscopic analyses of gelatin

    NASA Astrophysics Data System (ADS)

    Ibrahim, Medhat; Mahmoud, Abdel Aziz; Osman, Osama; Abd El-Aal, Mohamed; Eid, May

    2011-10-01

    The molecular structure of gelatin was studied using Fourier transform infrared spectroscopy FTIR. The spectrum is subjected to deconvolution in order to elucidate the constituents of the molecular structure. B3LYP/6-31g** was used to study 13 amino acids then the scaled spectrum was compared to those of protein in order to describe the contribution of each amino acid into protein structure. A special interest was paid to the NH and C dbnd O region. The reactivity of each amino acid was studied in terms of some important physical parameters like total dipole moment and HOMO/LUMO which describe the interaction of amino acid with their surrounding molecules. Results indicated that B3LYP/6-31g** model is a suitable and precise method for studying molecular structure of protein.

  2. Very high finesse optical-feedback cavity-enhanced absorption spectrometer for low concentration water vapor isotope analyses.

    PubMed

    Landsberg, J; Romanini, D; Kerstel, E

    2014-04-01

    So far, cavity-enhanced absorption spectroscopy (CEAS) has been based on optical cavities with a high finesse F that, however, has been limited by mirror reflectivity and by cavity transmission considerations to a few times 10,000. Here, we demonstrate a compact near-infrared optical-feedback CEAS instrument for water vapor isotope ratio measurements, with F>140,000. We show that this very high finesse can be effectively exploited to improve the detection sensitivity to the full extent predicted by the increased effective path length to reach a noise equivalent absorption sensitivity of 5.7×10(-11)  cm(-1) Hz(-1/2) for a full spectrum registration (including possible effects of interference fringes and fit model inadequacies). PMID:24686607

  3. Analytical procedure for the simultaneous voltammetric determination of trace metals in food and environmental matrices. Critical comparison with atomic absorption spectroscopic measurements.

    PubMed

    Melucci, Dora; Torsi, Giancarlo; Locatelli, Clinio

    2007-01-01

    An analytical procedure fit for the simultaneous determination of copper (II), chromium(VI), thallium(I), lead(II), tin(II), antimony(III), and zinc(II) by square wave anodic stripping voltammetry (SWASV) in three interdependent environmental matrices involved in foods and food chain as meals, cereal plants and soils is described. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 (meals and cereal plants) and HCl-HNO3 (soils) acidic attack mixtures. 0.1 mol/L dibasic ammonium citrate pH 8.5 was employed as the supporting electrolyte. The voltammetric measurements were carried out using, as working electrode, a stationary hanging mercury drop electrode (HMDE) and a platinum electrode and an Ag/AgCl/KClsat electrode as auxiliary and reference electrodes, respectively. The analytical procedure was verified by the analyses of the standard reference materials: Wholemeal BCR-CRM 189, Tomato Leaves NIST-SRM 1573a and Montana Soil Moderately Elevated Traces NIST-SRM 2711. For all the elements in the certified matrix, the precision as repeatability, expressed as relative standard deviation (Sr %) was lower than 5%. The accuracy, expressed as percentage relative error (e %) was of the order of 3-7%, while the detection limits were in the range 0.015-0.103 microg/g. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meal samples, cereal plants and soils samples drawn in sites devoted to agricultural practice. A critical comparison with spectroscopic measurements is also discussed. PMID:17822223

  4. A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255. II. Emission- and absorption-line variability time lags

    NASA Astrophysics Data System (ADS)

    Saturni, F. G.; Trevese, D.; Vagnetti, F.; Perna, M.; Dadina, M.

    2016-03-01

    Context. The study of high-redshift bright quasars is crucial to gather information about the history of galaxy assembly and evolution. Variability analyses can provide useful data on the physics of quasar processes and their relation with the host galaxy. Aims: In this study, we aim to measure the black hole mass of the bright lensed BAL QSO APM 08279+5255 at z = 3.911 through reverberation mapping, and to update and extend the monitoring of its C IV absorption line variability. Methods: We perform the first reverberation mapping of the Si IV and C IV emission lines for a high-luminosity quasar at high redshift with the use of 138 R-band photometric data and 30 spectra available over 16 years of observations. We also cross-correlate the C IV absorption equivalent width variations with the continuum light curve to estimate the recombination time lags of the various absorbers and infer the physical conditions of the ionised gas. Results: We find a reverberation-mapping time lag of ~900 rest-frame days for both Si IV and C IV emission lines. This is consistent with an extension of the BLR size-to-luminosity relation for active galactic nuclei up to a luminosity of ~1048 erg s-1, and implies a black hole mass of 1010 M⊙. Additionally, we measure a recombination time lag of ~160 days in the rest frame for the C IV narrow absorption system, which implies an electron density of the absorbing gas of ~2.5 × 104 cm-3. Conclusions: The measured black hole mass of APM 08279+5255 indicates that the quasar resides in an under-massive host-galaxy bulge with Mbulge ~ 7.5MBH, and that the lens magnification is lower than ~8. Finally, the inferred electron density of the narrow-line absorber implies a distance of the order of 10 kpc of the absorbing gas from the quasar, placing it within the host galaxy.

  5. Pigment analyses of a portrait and paint box of Turkish artist Feyhaman Duran (1886-1970): The EDXRF, FT-IR and micro Raman spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Akyuz, Sevim; Akyuz, Tanil; Emre, Gulder; Gulec, Ahmet; Basaran, Sait

    2012-04-01

    The samples obtained from nine different places of Ataturk portrait (oil on canvas, 86 cm × 136 cm) by Feyhaman Duran (1886-1970), one of the famous Turkish painters of the 20th century, together with five pigment samples (two different white, two different yellow and blue), obtained as powders from artist's paint box, were analysed by EDXRF, FT-IR and micro-Raman spectroscopic methods, in order to characterise the pigments used by the artist. Informative Raman signals were not obtained from most of the samples of the portrait, due to huge fluorescence caused by the presence of impurities and organic materials in the samples, however the Raman spectrum of the sample from skin coloured part of the portrait and the pigment samples obtained from the paint box of the artist were found to be very informative to shed light on the determination of the pigments used. Analysis revealed the presences of chrome yellow (PbCrO4), strontium yellow (SrCrO4) and Cadmium yellow (CdS) as yellow, chromium oxides (Cr2O3 and Cr2O3·2H2O) as green, natural red ochre as red, brown ochre as brown and ivory black or bone black (C + Ca3(PO4)2) and manganese oxides (Mn2O3 and MnO2) as black pigments, in the composition of the Ataturk portrait. Lead white (2PbCO3·Pb(OH)2), calcite (CaCO3), barite (BaSO4), zinc white (ZnO) and titanium white (TiO2) were used as extenders to lighten the colours and/or as for ground level painting. Powder pigment samples, obtained from the paint box of artist, were found to be mixed pigments rather than pure ones.

  6. Exponential Sum Absorption Coefficients of Phosphine from 2750 to 3550/cm for Application to Radiative Transfer Analyses on Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Temma, T.; Baines, K. H.; Butler, R. A. H.; Brown, L. R.; Sagui, L.; Kleiner, I.

    2006-01-01

    PH3 exponential sum k coefficients were computed between 2750 and 3550/cm (2.82-3.64 (microns), in view of future application to radiative transfer analyses of Jupiter and Saturn in a phosphine absorption band near 3 microns. The temperature and pressure of this data set cover the ranges from 80 to 350 K and from 10 (exp -3)to 10(exp 1) bars, respectively. Transmission uncertainty incurred by the use of the k coefficients is smaller than a few percent as long as the radiation is confined above an altitude of a few bars in the giant planets. In spectral regions of weak absorption at high pressures close to 10 bars, contributions from far wings of strong absorption lines must be carefully taken into account. Our data set helps map the three-dimensional distribution of PH3 on the giant planets, revealing their global atmospheric dynamics extending down to the deep interior. The complete k coefficient data set of this work is available at the Web site of the NASA Planetary Data System Atmospheres Node.

  7. Differential activity and structure of highly similar peroxidases. Spectroscopic, crystallographic, and enzymatic analyses of lignifying Arabidopsis thaliana peroxidase A2 and horseradish peroxidase A2.

    PubMed

    Nielsen, K L; Indiani, C; Henriksen, A; Feis, A; Becucci, M; Gajhede, M; Smulevich, G; Welinder, K G

    2001-09-18

    Anionic Arabidopsis thaliana peroxidase ATP A2 was expressed in Escherichia coli and used as a model for the 95% identical commercially available horseradish peroxidase HRP A2. The crystal structure of ATP A2 at 1.45 A resolution at 100 K showed a water molecule only 2.1 A from heme iron [Ostergaard, L., et al. (2000) Plant Mol. Biol. 44, 231-243], whereas spectroscopic studies of HRP A2 in solution at room temperature [Feis, A., et al. (1998) J. Raman Spectrosc. 29, 933-938] showed five-coordinated heme iron, which is common in peroxidases. Presented here, the X-ray crystallographic, single-crystal, and solution resonance Raman studies at room temperature confirmed that the sixth coordination position of heme iron of ATP A2 is essentially vacant. Furthermore, electronic absorption and resonance Raman spectroscopy showed that the heme environments of recombinant ATP A2 and glycosylated plant HRP A2 are indistinguishable at neutral and alkaline pH, from room temperature to 12 K, and are highly flexible compared with other plant peroxidases. Ostergaard et al. (2000) also demonstrated that ATP A2 expression and lignin formation coincide in Arabidopsis tissues, and docking of lignin precursors into the substrate binding site of ATP A2 predicted that coniferyl and p-coumaryl alcohols were good substrates. In contrast, the additional methoxy group of the sinapyl moiety gave rise to steric hindrance, not only in A2 type peroxidases but also in all peroxidases. We confirm these predictions for ATP A2, HRP A2, and HRP C. The specific activity of ATP A2 was lower than that of HRP A2 (pH 4-8), although a steady-state study at pH 5 demonstrated very little difference in their rate constants for reaction with H2O2 (k1 = 1.0 microM(-1) x s(-1). The oxidation of coniferyl alcohol, ferulic, p-coumaric, and sinapic acids by HRP A2, and ATP A2, however, gave modest but significantly different k3 rate constants of 8.7 +/- 0.3, 4.0 +/- 0.2, 0.70 +/- 0.03, and 0.04 +/- 0.2 microM(-1) x

  8. Reactivity-activity relationships of oral anti-diabetic vanadium complexes in gastrointestinal media: an X-ray absorption spectroscopic study.

    PubMed

    Levina, Aviva; McLeod, Andrew I; Kremer, Lauren E; Aitken, Jade B; Glover, Christopher J; Johannessen, Bernt; Lay, Peter A

    2014-10-01

    The reactions of oral V(V/IV) anti-diabetic drugs within the gastrointestinal environment (particularly in the presence of food) are a crucial factor that affects their biological activities, but to date these have been poorly understood. In order to build up reactivity-activity relationships, the first detailed study of the reactivities of typical V-based anti-diabetics, Na3V(V)O4 (A), [V(IV)O(OH2)5](SO4) (B), [V(IV)O(ma)2] (C, ma = maltolato(-)) and (NH4)[V(V)(O)2(dipic)] (D, dipic = pyridine-2,5-dicarboxylato(2-)) with simulated gastrointestinal (GI) media in the presence or absence of food components has been performed by the use of XANES (X-ray absorption near edge structure) spectroscopy. Changes in speciation under conditions that simulate interactions in the GI tract have been discerned using correlations of XANES parameters that were based on a library of model V(V), V(IV), and V(III) complexes for preliminary assessment of the oxidation states and coordination numbers. More detailed speciation analyses were performed using multiple linear regression fits of XANES from the model complexes to XANES obtained from the reaction products from interactions with the GI media. Compounds B and D were relatively stable in the gastric environment (pH ∼ 2) in the absence of food, while C was mostly dissociated, and A was converted to [V10O28](6-). Sequential gastric and intestinal digestion in the absence of food converted A, B and D to poorly absorbed tetrahedral vanadates, while C formed five- or six-coordinate V(V) species where the maltolato ligands were likely to be partially retained. XANES obtained from gastric digestion of A-D in the presence of typical food components converged to that of a mixture of V(IV)-aqua, V(IV)-amino acid and V(III)-aqua complexes. Subsequent intestinal digestion led predominantly to V(IV) complexes that were assigned as citrato or complexes with 2-hydroxyacidato donor groups from other organic compounds, including certain

  9. Description of the Role of Shot Noise in Spectroscopic Absorption and Emission Measurements with Photodiode and Photomultiplier Tube Detectors: Information for an Instrumental Analysis Course

    ERIC Educational Resources Information Center

    McClain, Robert L.; Wright, John C.

    2014-01-01

    A description of shot noise and the role it plays in absorption and emission measurements using photodiode and photomultiplier tube detection systems is presented. This description includes derivations of useful forms of the shot noise equation based on Poisson counting statistics. This approach can deepen student understanding of a fundamental…

  10. Spectroscopic evidence for the formation of singlet molecular oxygen (/sup 1/. delta. /sub g/O/sub 2/) upon irradiation of a solvent-oxygen (/sup 3/Sigma/sub g//sup -/O/sub 2/) cooperative absorption band

    SciTech Connect

    Scurlock, R.D.; Ogilby, P.R.

    1988-01-20

    It is well-known that the presence of molecular oxygen (/sup 3/..sigma../sub g//sup -/O/sub 2/) in a variety of organic solvents causes an often substantial red shift in the solvent absorption spectrum. This extra, broad absorption feature is reversibly removed by purging the solvent with nitrogen gas. Mulliken and Tsubomura assigned the oxygen-dependent absorption band to a transition from a ground state solvent-oxygen complex to a solvent-oxygen charge transfer (CT) state (sol/sup .+/O/sub 2//sup .-/). In addition to the broad Mulliken CT band, there are, often in the same spectral region, distinct singlet-triplet transitions (T/sub 1/ reverse arrow S/sub 0/) which are enhanced by molecular oxygen (/sup 3/..sigma../sub g//sup -/O/sub 2/). Since both of these solvent-oxygen cooperative transitions may result in the formation of reactive oxygenating species, singlet molecular oxygen (/sup 1/..delta../sub g/O/sub 2/) and/or the superoxide ion (O/sub 2//sup .-/), it follows that recent studies have focused on unsaturated hydrocarbon oxygenation subsequent to the irradiation of the oxygen-induced absorption bands in both the solution phase and cryogenic (10 K) glasses. In these particular experiments, oxygenated products characteristic of both /sup 1/..delta../sub g/O/sub 2/ and O/sub 2//sub .-/ were obtained, although the systems studied appeared to involve the participation of one intermediate at the exclusion of the other. In this communication, the authors provide, for the first time, direct spectroscopic evidence for the formation of /sup 1/..delta../sub g/O/sub 2/ following a solvent-oxygen (/sup 3/..sigma../sub g//sup -/O/sub 2/) cooperative absorption. They have observed, in a time-resolved experiment, a near-IR luminescence subsequent to laser excitation of the oxygen-induced absorption bands of mesitylene, p-xylene, o-xylene, toluene, and benzene at 355 nm and 1,4-dioxane at 266 nm. They suggest that this signal is due to /sup 1/..delta../sub g/O/sub 2

  11. X-ray photoelectron and optical absorption spectroscopic studies on the dye chlorodiane blue, used as a carrier generation molecule in organic photoconductors

    SciTech Connect

    Pacansky, J.; Waltman, R.J.

    1992-07-01

    The dye chlorodiane blue, used as a carrier generation molecule in organic photoconductors, is characterized via optical absorption and X-ray photoelectron spectroscopy, and the results are interpreted on the basis of ab initio quantum mechanical molecular models. These data indicate that chlorodiane blue exists as azo-enol and hydrazone-quinone chemical structures and it is the hydrazone-quinone form that provides the higher xerographic gain in electrophotographic applications. Optimized geometries, atomic charges, and molecular orbital plots and energies are reported for both the azo-enol and hydrazone-quinone forms of chlorodiane blue. The two structural forms of the dye are experimentally distinguishable via both optical absorption and X-ray photoelectron spectroscopy, and the wavelength and chemical shifts, respectively, are interpreted via the theoretical results. 29 refs., 9 figs., 4 tabs.

  12. Characterization of the physico-chemical properties of polymeric materials for aerospace flight. [differential thermal and atomic absorption spectroscopic analysis of nickel cadmium batteries

    NASA Technical Reports Server (NTRS)

    Rock, M.

    1981-01-01

    Electrodes and electrolytes of nickel cadmium sealed batteries were analyzed. Different thermal analysis of negative and positive battery electrodes was conducted and the temperature ranges of occurrence of endotherms indicating decomposition of cadmium hydroxide and nickel hydroxide are identified. Atomic absorption spectroscopy was used to analyze electrodes and electrolytes for traces of nickel, cadmium, cobalt, and potassium. Calibration curves and data are given for each sample analyzed. Instrumentation and analytical procedures used for each method are described.

  13. X-ray Photoelectron Spectroscopic Analyses of Corrosion Products Formed on Rock Bolt Carbon Steel in Chloride Media with Bicarbonate and Silicate Ions

    SciTech Connect

    Deodeshmukh, Vinay; Venugopal, A; Chandra, Dhanesh; Yilmaz, Ahmet; Daemen, Jack; Jones, D A.; Lea, Alan S.; Engelhard, Mark H.

    2004-11-01

    The passivation behavior of Yucca Mountain Repository rock bolt carbon steel in deaerated 3.5% NaCl solution containing SiO{sub 3}{sup 2} and HCO{sub 3} ions was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopic methods. Polarization results indicate that combinations of silicate and bicarbonate anions decrease the passive current density and raise the pitting potential. XPS results indicate the enrichment of silica at passive potentials and the formation of mixed FeCO{sub 3} and silica film at lower potentials. This change in film composition was responsible for the changes in corrosion rate at lower and higher potentials. XPS results also support the thermodynamic data with regard to the occurrence of second oxidation peak observed in the polarization curves to be due to the oxidation of FeCO{sub 3} to Fe{sub 2}O{sub 3}.

  14. Infrared Spectroscopic Analyses of Sulfate, Nitrate, and Carbonate-bearing Atacama Desert Soils: Analogs for the Interpretation of Infrared Spectra from the Martian Surface

    NASA Technical Reports Server (NTRS)

    Dalton, J. B.; Dalton, J. B.; Ewing, S. A.; Amundson, R.; McKay, C. P.

    2005-01-01

    The Atacama Desert of northern Chile is the driest desert on Earth, receiving only a few mm of rain per decade. The Mars climate may, in the past, have been punctuated by short-lived episodes of aqueous activity. The paleo-Martian environment may have had aqueous conditions similar to the current conditions that exist in the Atacama, and Mars soils may have formed with soil chemistry and mineralogy similar to those found in the Atacama. Remote and in-situ analysis of the Martian surface using infrared technology has a long heritage. Future investigations of the subsurface mineralogy are likely to build upon this heritage, and will benefit from real life lessons to be learned from terrestrial analog studies. To that end, preliminary results from a near- and mid-infrared spectroscopic study of Atacama soil profiled at a range of depths are presented.

  15. Color change of tourmaline by heat treatment and electron beam irradiation: UV-Visible, EPR, and Mid-IR spectroscopic analyses

    NASA Astrophysics Data System (ADS)

    Maneewong, Apichate; Seong, Baek Seok; Shin, Eun Joo; Kim, Jeong Seog; Kajornrith, Varavuth

    2016-01-01

    The color of pink tourmaline gemstone changed to colorless when heating at temperature of 600 °C in air. This colorless tourmaline recovered its pink color when irradiated with an electron beam (e-beam) of 800 kGy. The origin of the color change was investigated in three types of tourmaline gemstones, two pink are from Afghanistan and one green are from Nigeria, by using Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and Energy Dispersive X-ray Fluorescence (EDXRF). The UV-Vis absorption spectrum of the pink tourmaline with higher Mn concentration (T2, 0.24 wt%) showed characteristic absorption peaks originating from the Mn3+ color center: two absorption bands centered at wavelength of 396 and 520 nm, respectively. Both absorption bands disappeared when heated in air at 600 °C and then reappeared when irradiated with an e-beam at 800 kGy. EPR T2 spectra showed that the color change was related to the valence change of Mn3+ to Mn2+ and vice versa. The pink tourmaline of lower MnO content (T1, 0.08 wt%) also became colorless when heated, but the color was not recovered when the gemstone underwent e-beam irradiation. Instead, a yellow color was obtained. UV-Vis and FTIR spectra indicated that this yellow color originated from a decomposition of the hydroxyl group (-OH) into O- and Ho by the e-beam irradiation. Green tourmaline did not show any color change with either heat treatment or e-beam irradiation.

  16. X-ray absorption spectroscopic study of LiCoO2 as the negative electrode of lithium-ion batteries.

    PubMed

    Chadwick, Alan V; Savin, Shelley L P; Alcántara, Ricardo; Fernández Lisbona, Diego; Lavela, Pedro; Ortiz, Gregorio F; Tirado, José L

    2006-05-12

    Lithium cobalt oxide (LiCoO(2)) particles are modified using rotor blade grinding and re-annealing and used as the active electrode material versus lithium in the 3-0 V potential interval, in which a maximum capacity of 903 mA h g(-1) is achieved. X-ray absorption near edge structure spectra reveal the complete reduction of Co(3+) to Co metal at 0 V. Cell recharge leads to an incomplete reoxidation of cobalt. A maximum reversible capacity of 812 mA h g(-1) is obtained, although a poor capacity retention upon prolonged cycling may limit its application. PMID:16612798

  17. Effects of oxidation state on metal ion binding by Medicago sativa (alfalfa): Atomic and X-ray absorption spectroscopic studies with Fe(II) and Fe(III)

    SciTech Connect

    Tiemann, K.J.; Gardea-Torresdey, J.L.; Gamez, G.; Dokken, K.; Cano-Aguilera, I.; Renner, M.W.; Furenlid, L.R.

    2000-02-15

    The authors present here experimental results that investigate the effects of metal-ion binding on iron-ion sorption to and recovery from alfalfa biomass. Fe(II)- and Fe(III)-ion binding were measured in order to ascertain the differences in binding strengths due to changes in oxidation state. Stronger binding was found for iron(III)-biomass as compared to iron(II)-biomass. The optimal pH for iron uptake was determined to be 5. The results of pH binding profile, orion desorption, and temperature-dependent binding experiments as well as X-ray spectroscopic (XAS) measurements all suggest that binding of iron by alfalfa biomass may be occurring through carboxyl ligands. The XAS experiments further demonstrate that the metal binding proceeds without an oxidation state change, and both iron(II) and iron(III) have similar coordination environments. The information presented will assist in understanding the binding of other metals to alfalfa biomass and in developing methods for their recovery.

  18. X-ray absorption spectroscopic studies of the diiron center in methane monooxygenase in the presence of substrate and the coupling protein of the enzyme system

    SciTech Connect

    DeWitt, J.G.; Rosenzweig, A.C.; Salifoglou, A.

    1995-05-10

    The interaction among the hydroxylase component of methane monooxygenase (MMO) from Methylococcus capsulatus (Bath), the coupling protein of the MMO enzyme system (component B), and substrate has been investigated by using Fe K-edge X-ray absorption spectroscopy (XAS). Fe K-edge extended X-ray absorption fine structure (EXAFS) studies of the semimet form of the hydroxylase in the presence of the coupling protein, 1-bromo-1-propene, and both the coupling protein and 1-bromo-1-propene revealed small differences in the appearance of the EXAFS above k = 8 {Angstrom}{sup {minus}1} as compared to the noncomplexed hydroxylase. No dramatic change in the Fe coordination was seen in fits to the data. The average first shell Fe-O/N distance for the complexed forms of the semimet hydroxylase ranged between 2.06 and 2.08 {Angstrom}, which is comparable to the distance found for the noncomplexed form, 2.06-2.09 {Angstrom}. Although the average first shell coordination was similar for all samples, a difference was seen in the distribution of long vs short distance contributions to the first shell coordination sphere for samples with component B present. This difference was accompanied by a small but consistent decrease in the Fe-Fe distance of the B-complexed hydroxylase samples, from 3.42 to 3.39 {angstrom}.

  19. Structure of the dinuclear active site of urease. X-ray absorption spectroscopic study of native and 2-mercaptoethanol-inhibited bacterial and plant enzymes

    SciTech Connect

    Wang, Shengke; Scott, R.A. ); Lee, M.H.; Hausinger, R.P. ); Clark, P.A.; Wilcox, D.E. )

    1994-04-13

    The structures of the dinuclear Ni(II) active sites of urease from jack bean and Klebsiella aerogenes are compared with and without the addition of the inhibitor 2-mercaptoethanol (2-ME). No significant differences are observed by nickel K-edge X-ray absorption spectroscopy between the plant and bacterial enzymes. The Ni X-ray absorption edge spectra display an 8332-eV 1s[yields]3d peak intensity similar to that observed for five-coordinate Ni(II) compounds[sup 1] for both native and 2-ME-bound derivatives. Curve-fitting of Ni EXAFS data indicates that the average Ni(II) coordination environment in native urease can be described as Ni(imidazole)[sub x](N,O)[sub 5[minus]x], with x = 2 or 3. Addition of 2-ME results in replacement of one of the non-imidazole (N,O) ligands with (S,Cl) (most likely the thiolate sulfur of 2-ME) and results in the appearance of a new peak in the Fourier transforms that can only be fit with a Ni[center dot][center dot][center dot]Ni scattering component at a Ni-Ni distance of [approximately]3.26 [angstrom]. A structure for this 2-ME-bound dinuclear site is proposed to contain the two Ni(II) ions bridged by the thiolate sulfur of 2-ME.

  20. Spectroscopic characterization of C7H3(+) and C7H3˙: electronic absorption and fluorescence in 6 K neon matrices.

    PubMed

    Chakraborty, Arghya; Fulara, Jan; Dietsche, Rainer; Maier, John P

    2014-04-21

    Mass selective deposition of C7H3(+) (m/z = 87) into solid neon reveals the 1(1)A1←X(1)A1 electronic absorption system of hepta-1,2,3,4,5,6-heptahexaenylium cation B(+) [H2CCCCCCCH](+) with an origin band at 441.3 nm, 1(1)A'←X(1)A' transition of 2,4-pentadiynylium,1-ethynyl cation C(+) [HCCCHCCCCH](+) starting at 414.6 nm and the 1(1)A1←X(1)A1 one of cyclopropenylium,1,3-butadiynyl cation A(+) [HCCCCC<(CH=CH)](+) with an onset at 322.2 nm. Vibrationally resolved fluorescence was observed for isomer B(+) upon laser excitation of the absorption bands in the 1(1)A1←X(1)A1 transition. After neutralization of the cations in the matrix five absorption systems of the C7H3 neutral radicals starting at 530.3, 479.4, 482.3, 325.0 and 302.5 nm were detected. These were identified as the 1(2)A'←X(2)A' and 2(2)A'←X(2)A' electronic transitions of 2-(buta-1,3-diynyl)cycloprop-2yl-1-1ylidene E˙ [HCCCCC<(C=CH2)]˙, 1(2)B1←X(2)B1 of 1,2,3,4,5,6-heptahexaenyl B˙ [H2CCCCCCCH]˙, 3(2)B1←X(2)B1 of 3-buta-1,3-diynyl-cyclopropenyl A˙ [HCCCCC<(CH=CH)]˙ and 2(2)B1←X(2)A2 transition of 1,2-divinylidene-cyclopropanyl radical F˙ [HCC-cyc-(CCHC)-CCH]˙, respectively. The assignment is based on calculated vertical excitation energies using the CASPT2 method. Comparison of the calculated harmonic vibrational frequencies with those inferred from the spectra supports the assignment. PMID:24603977

  1. Spectroscopic (FT-IR and FT-Raman) studies, NBO, HOMO-LUMO, NMR analyses and thermodynamics functions of 5-bromo-2-methoxybenzaldehyde

    NASA Astrophysics Data System (ADS)

    Balachandran, V.; Santhi, G.; Karpagam, V.

    2013-04-01

    The (FT-IR and FT-Raman) spectral properties of 5-bromo-2-methoxybenzaldehyde (BMB) are studied using density functional theory (DFT) employing B3LYP/6-311++G (d) and B3LYP/6-311++G (d, p) levels of theory. There are four conformers, C1, C2, C3, and C4 for this molecule. The computational results diagnose the most stable conformer of BMB as the C1 form. The optimized geometrical parameters obtained by B3LYP/6-311++G (d, p) method show good agreement with experimental X-ray data. A study on the electronic properties, such as HOMO and LUMO energies, is performed. The isotropic chemical shift computed by 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the BMB calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations. The MEP surface reflects the chemical reactivity of a molecule. The thermodynamic functions (heat capacity, internal heat energy, Gibbs energy and entropy) from spectroscopic data by statistical methods were obtained for the range of temperature 100-1000 K. The energetic behavior of the compound in different solvent medium (water, ethanol, and methanol) was examined by applying polarizable continuum model (PCM). The complete molecular orbital simulations and theoretical UV-visible spectra carried out in this study yield better understanding of charge delocalization pattern and stability of the title molecules to a greater extent.

  2. In-Situ Spectroscopic Analyses of the Dye Uptake on ZnO and TiO2 Photoanodes for Dye-Sensitized Solar Cells.

    PubMed

    Shahzad, Nadia; Pugliese, Diego; Shahzad, Muhammad Imran; Tresso, Elena

    2015-08-01

    UV-Vis spectroscopic measurements have been performed on Dye-Sensitized Solar Cell (DSSC) photoanodes at different dye impregnation times ranging from few minutes to 24 hours. In addition to the traditional absorbance experiments, based on diffuse and specular reflectance of dye impregnated thin films and on the desorption of dye molecules from the photoanodes by means of a basic solution, an alternative in-situ solution depletion measurement, which enables fast and continuous evaluation of dye uptake, has been employed. Two different nanostructured semiconducting oxide films (mesoporous TiO2 and sponge-like ZnO) and two different dyes, the traditional Ruthenizer 535-bisTBA (N719) and a newly introduced metal-free organic dye based on a hemi-squaraine molecule (CT1), have been analyzed. DSSCs have been fabricated with the dye-impregnated photoanodes using a customized microfluidic architecture. The dye adsorption results are discussed and correlated to the obtained DSSC electrical performances such as photovoltaic conversion efficiencies and Incident Photon-to-electron Conversion Efficiency (IPCE) spectra. It is shown that simple UV-Vis measurements can give useful insights on the dye adsorption mechanisms and on the evaluation of the optimal impregnation times. PMID:26369186

  3. X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

    SciTech Connect

    DeWitt, J.G.

    1992-12-01

    The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 [Angstrom]. The Fe-Fe distance was determined to be 3.4 [Angstrom]. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

  4. X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

    SciTech Connect

    DeWitt, J.G.

    1992-12-01

    The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 {Angstrom}. The Fe-Fe distance was determined to be 3.4 {Angstrom}. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

  5. [2H/H] Isotope ratio analyses of [2H5]cholesterol using high-temperature conversion elemental analyser isotope-ratio mass spectrometry: determination of cholesterol absorption in normocholesterolemic volunteers.

    PubMed

    Godin, Jean-Philippe; Richelle, Myriam; Metairon, Sylviane; Fay, Laurent-Bernard

    2004-01-01

    This paper validates the use of high-temperature conversion elemental analyser isotope-ratio mass spectrometry (TC-EA/IRMS) for measuring the [(2)H/H] enrichment of plasma [(2)H(5)]cholesterol. From a molecular point of view, the free cholesterol is initially separated from plasma by thin-layer chromatography (TLC) and then injected onto the TC-EA reactor which converts cholesterol molecules into CO and H(2) gases. The slope of the curve of the experimental mole percent excess (MPE((exp.))) versus MPE((theor.)) was very close to 1, demonstrating that no significant isotopic fractionation was observed during all processing of the samples (i.e., isolation of plasma free cholesterol by TLC and pyrolysis in the TC-EA reactor). Excellent linearity (r(2) = 0.9994, n = 4) of delta ( per thousand ) of [(2)H/H] isotopic measurements versus mole percent (MP) was assessed over the range 0 to 0.1 MP. The precision of the [(2)H/H] measurement, evaluated with two calibration points processed with TLC, was delta(2)H(V-SMOW) = -192.5 +/- 3.4 per thousand and delta(2)H(V-SMOW) = -136.9 +/- 2.9 per thousand. The standard deviations of the within-assay and between-assay repeatabilities of the analytical process, evaluated using the quality control (QC) of plasma samples, were 4.6 and 6.1 per thousand, respectively. Plant sterols are known to reduce cholesterol absorption and therefore were used as a positive control in a clinical study performed with normocholesterolemic volunteers. This present method produces biological results consistent with those already reported in the literature. PMID:14755619

  6. Constraining the N2O5 UV absorption cross section from spectroscopic trace gas measurements in the tropical mid-stratosphere

    NASA Astrophysics Data System (ADS)

    Kritten, L.; Butz, A.; Chipperfield, M. P.; Dorf, M.; Dhomse, S.; Hossaini, R.; Oelhaf, H.; Prados-Roman, C.; Wetzel, G.; Pfeilsticker, K.

    2014-09-01

    The absorption cross section of N2O5, σN2O5(λ, T), which is known from laboratory measurements with the uncertainty of a factor of 2 (Table 4-2 in (Jet Propulsion Laboratory) JPL-2011; the spread in laboratory data, however, points to an uncertainty in the range of 25 to 30%, Sander et al., 2011), was investigated by balloon-borne observations of the relevant trace gases in the tropical mid-stratosphere. The method relies on the observation of the diurnal variation of NO2 by limb scanning DOAS (differential optical absorption spectroscopy) measurements (Weidner et al., 2005; Kritten et al., 2010), supported by detailed photochemical modelling of NOy (NOx(= NO + NO2) + NO3 + 2N2O5 + ClONO2 + HO2NO2 + BrONO2 + HNO3) photochemistry and a non-linear least square fitting of the model result to the NO2 observations. Simulations are initialised with O3 measured by direct sun observations, the NOy partitioning from MIPAS-B (Michelson Interferometer for Passive Atmospheric Sounding - Balloon-borne version) observations in similar air masses at night-time, and all other relevant species from simulations of the SLIMCAT (Single Layer Isentropic Model of Chemistry And Transport) chemical transport model (CTM). Best agreement between the simulated and observed diurnal increase of NO2 is found if the σN2O5(λ, T) is scaled by a factor of 1.6 ± 0.8 in the UV-C (200-260 nm) and by a factor of 0.9 ± 0.26 in the UV-B/A (260-350 nm), compared to current recommendations. As a consequence, at 30 km altitude, the N2O5 lifetime against photolysis becomes a factor of 0.77 shorter at solar zenith angle (SZA) of 30° than using the recommended σN2O5(λ, T), and stays more or less constant at SZAs of 60°. Our scaled N2O5 photolysis frequency slightly reduces the lifetime (0.2-0.6%) of ozone in the tropical mid- and upper stratosphere, but not to an extent to be important for global ozone.

  7. X-Ray Absorption Fine Structure Spectroscopic Studies of Octakis(DMSO)Lanthanoid(III) Complexes in Solution And in the Solid Iodides

    SciTech Connect

    Persson, I.; Risberg, E.Damian; D'Angelo, P.; Panfilis, S.De; Sandstrom, M.; Abbasi, A.

    2009-06-04

    Octakis(DMSO)lanthanoid(III) iodides (DMSO = dimethylsulfoxide), [Ln(OS(CH{sub 3}){sub 2}){sub 8}]I{sub 3}, of most lanthanoid(III) ions in the series from La to Lu have been studied in the solid state and in DMSO solution by extended X-ray absorption fine structure (EXAFS) spectroscopy. L{sub 3}-edge and also some K-edge spectra were recorded, which provided mean Ln-O bond distances for the octakis(DMSO)lanthanoid(III) complexes. The agreement with the average of the Ln-O bond distances obtained in a separate study by X-ray crystallography was quite satisfactory. The crystalline octakis(DMSO)lanthanoid(III) iodide salts have a fairly broad distribution of Ln-O bond distances, ca. 0.1 {angstrom}, with a few disordered DMSO ligands. Their EXAFS spectra are in excellent agreement with those obtained for the solvated lanthanoid(III) ions in DMSO solution, both of which show slightly asymmetric distributions of the Ln-O bond distances. Hence, all lanthanoid(III) ions are present as octakis(DMSO)lanthanoid(III) complexes in DMSO solution, with the mean Ln-O distances centered at 2.50 (La), 2.45 (Pr), 2.43 (Nd), 2.41 (Sm), 2.40 (Eu), 2.39 (Gd), 2.37 (Tb), 2.36 (Dy), 2.34 (Ho), 2.33 (Er), 2.31 (Tm), and 2.29 {angstrom} (Lu). This decrease in the Ln-O bond distances is larger than expected from the previously established ionic radii for octa-coordination. This indicates increasing polarization of the Ln{sup III}-O(DMSO) bonds with increasing atomic number. However, the S(1s) electron transition energies in the sulfur K-edge X-ray absorption near-edge structure (XANES) spectra, probing the unoccupied molecular orbitals of lowest energy of the DMSO ligands for the [Ln(OS(CH{sub 3}){sub 2}){sub 8}]{sup 3+} complexes, change only insignificantly from Ln = La to Lu. This indicates that there is no appreciable change in the ?-contribution to the S-O bond, probably due to a corresponding increase in the contribution from the sulfur lone pair to the bonding.

  8. X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfur and chlorine centers in photographic materials

    SciTech Connect

    DeWitt, J.G.

    1993-01-01

    The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus (Bath) and Methylosinus trichosporium (OB3b) has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the hydroxylase consists of [approximately]6 N and O atoms at an average distance of 2.04[angstrom] in the oxidized form, increasing to 2.06-2.09[angstrom] in the semimet form, and 2.15 [angstrom] for the oxidized and semimet hydroxylase samples. No evidence for the presence of a short oxo bridge in the iron center was found. The presence of component B, the regulatory protein of the MMO enzyme system, had an effect on the distance distribution of first shell atoms in the hydroyxlase active site. No evidence of a Br contribution was seen in the hydroxylase EXAFS in the presence of a brominated substrate, suggesting the substrate binds more than 4[angstrom] from the iron center. An investigation of the EXAFS analysis technique using structurally-characterized iron dimers demonstrated that the results of the second shell fits exhibit a bias for the Fe-FE distance of the model compound from which the fitting parameters were obtained. An asymmetric pre-edge feature in the edge spectra of iron dimers was characteristic of oxo-bridge compounds, while a split pre-edge was characteristic of non-oxo-bridged compounds. Spectral sensitizing dyes and chemical sensitizing centers of importance to the photographic system were characterized by S and Cl K-edge X-ray absorption spectroscopy. The appearance of the S K-edge spectra was characteristic of the environment of the S atoms and oriented single-crystal studies permitted the assignment of the features. The nature and extend of interaction between S and Ag and Au was characterized using XAS and used to investigate the nature of the interaction between photographic dyes and the AgBr substrate.

  9. An X-ray absorption spectroscopic study of the metal site preference in Al{sub 1-x}Ga{sub x}FeO{sub 3}

    SciTech Connect

    Walker, James D.S.; Grosvenor, Andrew P.

    2013-01-15

    Magnetoelectric materials have potential for being introduced into next generation technologies, especially memory devices. The AFeO{sub 3} (Pna2{sub 1}; A=Al, Ga) system has received attention to better understand the origins of magnetoelectric coupling. The magnetoelectric properties this system exhibits depend on the amount of anti-site disorder present, which is affected by the composition and the method of synthesis. In this study, Al{sub 1-x}Ga{sub x}FeO{sub 3} was synthesized by the ceramic method and studied by X-ray absorption spectroscopy. Al L{sub 2,3}-, Ga K-, and Fe K-edge spectra were collected to examine how the average metal coordination number changes with composition. Examination of XANES spectra from Al{sub 1-x}Ga{sub x}FeO{sub 3} indicate that with increasing Ga content, Al increasingly occupies octahedral sites while Ga displays a preference for occupying the tetrahedral site. The Fe K-edge spectra indicate that more Fe is present in the tetrahedral site in AlFeO{sub 3} than in GaFeO{sub 3}, implying more anti-site disorder is present in AlFeO{sub 3}. - Graphical abstract: Al{sub 1-x}Ga{sub x}FeO{sub 3} has been investigated by XANES. Through examination of Al L{sub 2,3}-, Ga K-, and Fe K-edge XANES spectra, it was found that more anti-site disorder of the Fe atoms is present in AlFeO{sub 3} compared to in GaFeO{sub 3}. Highlights: Black-Right-Pointing-Pointer Al{sub 1-x}Ga{sub x}FeO{sub 3} was investigated by X-ray absorption spectroscopy. Black-Right-Pointing-Pointer Ga prefers to occupy the tetrahedral site in Al{sub 1-x}Ga{sub x}FeO{sub 3}. Black-Right-Pointing-Pointer Fe prefers to occupy the octahedral sites in Al{sub 1-x}Ga{sub x}FeO{sub 3} as x increases. Black-Right-Pointing-Pointer More anti-site disorder is present in AlFeO{sub 3} compared to in GaFeO{sub 3.}.

  10. A novel surface-sensitive X-ray absorption spectroscopic detector to study the thermal decomposition of cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Nonaka, Takamasa; Okuda, Chikaaki; Oka, Hideaki; Nishimura, Yusaku F.; Makimura, Yoshinari; Kondo, Yasuhito; Dohmae, Kazuhiko; Takeuchi, Yoji

    2016-09-01

    A surface-sensitive conversion-electron-yield X-ray absorption fine structure (CEY-XAFS) detector that operates at elevated temperatures is developed to investigate the thermal decomposition of cathode materials for Li-ion batteries. The detector enables measurements with the sample temperature controlled from room temperature up to 450 °C. The detector is applied to the LiNi0.75Co0.15Al0.05Mg0.05O2 cathode material at 0% state of charge (SOC) and 50% SOC to examine the chemical changes that occur during heating in the absence of an electrolyte. The combination of surface-sensitive CEY-XAFS and bulk-sensitive transmission-mode XAFS shows that the reduction of Ni and Co ions begins at the surface of the cathode particles at around 150 °C, and propagates inside the particle upon further heating. These changes with heating are irreversible and are more obvious at 50% SOC than at 0% SOC. The fraction of reduced Ni ions is larger than that of reduced Co ions. These results demonstrate the capability of the developed detector to obtain important information for the safe employment of this cathode material in Li-ion batteries.

  11. Absorption spectroscopic and FTIR studies on EDA complexes between TNT (2,4,6-trinitrotoluene) with amines in DMSO and determination of the vertical electron affinity of TNT

    NASA Astrophysics Data System (ADS)

    Sharma, S. P.; Lahiri, S. C.

    2008-06-01

    TNT (2,4,6-trinitrotoluene) formed deep red 1:1 CT complexes with chromogenic agents like isopropylamine, ethylenediamine, bis(3-aminopropyl)amine and tetraethylenepentamine in DMSO. The complexes were also observed in solvents like methanol, acetone, etc. when the amines were present in large excess. The isopropylamine, complex showed three absorption peaks (at 378, 532 and 629 nm) whereas higher amines showed four peaks (at 370, 463, 532 and 629 nm). The peak at 463 nm vanished rapidly. The peak of the complexes near 530 nm required about 8-10 min to develop and the complexes were stable for about an hour but the peak slowly shifted towards 500 nm and the complexes were found to be stable for more than 24 h. The evidence of complex formation was obtained from distinct spots in HPTLC plates and from the shifts in frequencies and formation of new peaks in FTIR spectra. The peaks near 460 nm (transient) and 530 nm may be due to Janovsky reaction but could not be established. The extinction coefficients of the complexes were determined directly which enabled the accurate determination of the association constants KDA with TNT and amines in stoichiometric ratios. The results were verified using iterative method. The quantfication of TNT was made using ɛ value of the complex with ethylenediamine. The vertical electron affinity ( EA) of TNT was calculated using the method suggested by Mulliken.

  12. Spectroscopic verification of zinc absorption and distribution in the desert plant Prosopis juliflora-velutina (velvet mesquite) treated with ZnO nanoparticles

    PubMed Central

    Hernandez-Viezcas, J.A.; Castillo-Michel, H.; Servin, A.D.; Peralta-Videa, J.R.; Gardea-Torresdey, J.L.

    2012-01-01

    The impact of metal nanoparticles (NPs) on biological systems, especially plants, is still not well understood. The aim of this research was to determine the effects of zinc oxide (ZnO) NPs in velvet mesquite (Prosopis juliflora-velutina). Mesquite seedlings were grown for 15 days in hydroponics with ZnO NPs (10 nm) at concentrations varying from 500 to 4000 mg L−1. Zinc concentrations in roots, stems and leaves were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). Plant stress was examined by the specific activity of catalase (CAT) and ascorbate peroxidase (APOX); while the biotransformation of ZnO NPs and Zn distribution in tissues was determined by X-ray absorption spectroscopy (XAS) and micro X-ray fluorescence (μXRF), respectively. ICP-OES results showed that Zn concentrations in tissues (2102 ± 87, 1135 ± 56, and 628 ± 130 mg kg−1 d wt in roots, stems, and leaves, respectively) were found at 2000 mg ZnO NPs L−1. Stress tests showed that ZnO NPs increased CAT in roots, stems, and leaves, while APOX increased only in stems and leaves. XANES spectra demonstrated that ZnO NPs were not present in mesquite tissues, while Zn was found as Zn(II), resembling the spectra of Zn(NO3)2. The μXRF analysis confirmed the presence of Zn in the vascular system of roots and leaves in ZnO NP treated plants. PMID:22820414

  13. Constraining the N2O5 UV absorption cross-section from spectroscopic trace gas measurements in the tropical mid-stratosphere

    NASA Astrophysics Data System (ADS)

    Kritten, L.; Butz, A.; Chipperfield, M. P.; Dorf, M.; Dhomse, S.; Hossaini, R.; Oelhaf, H.; Prados-Roman, C.; Wetzel, G.; Pfeilsticker, K.

    2014-02-01

    The absorption cross-section of N2O5, σN2O5(λ, T), which is known from laboratory measurements with the uncertainty of a factor of 2 (Table 4-2 in JPL-2011, Sander et al., 2011), was investigated by balloon-borne observations of the relevant trace gases in the tropical mid-stratosphere. The method relies on the observation of the diurnal variation of NO2 supported by detailed photochemical modelling of NOy (NOx(= NO + NO2) + NO3 + 2N2O5 + ClONO2 + HO2NO2 +BrONO2 + HNO3) photochemistry. Simulations are initialised with O3 measured by direct sun observations, the NOy partitioning from MIPAS-B (Michelson Interferometer for Passive Atmospheric Sounding-Balloon) observations in similar air masses at nighttime, and all other relevant species from simulations of the SLIMCAT chemical transport model (CTM). Best agreement between the simulated and observed diurnal increase of NO2 is found if the σN2O5(λ, T) is scaled by a factor of 1.6 ± 0.8 in the UV-C (200-260 nm) and by a factor of 0.9 ± 0.26 in the UV-B/A (260-350 nm), compared to current recommendations. In consequence, at 30 km altitude, the N2O5 lifetime against photolysis becomes a factor of 0.77 shorter at solar zenith angle (SZA) of 30° than using the recommended σN2O5 (λ, T), and stays more or less constant at SZAs of 60°. Our scaled N2O5 photolysis frequency slightly reduces the lifetime (0.2-0.6%) of ozone in the tropical mid- and upper stratosphere, but not to an extent to be important for global ozone.

  14. Spectroscopic analysis of small organic molecules: A comprehensive near-edge x-ray-absorption fine-structure study of C{sub 6}-ring-containing molecules

    SciTech Connect

    Kolczewski, C.; Puettner, R.; Martins, M.; Schlachter, A.S.; Snell, G.; Sant'Anna, M.M.; Hermann, K.; Kaindl, G.

    2006-01-21

    We report high-resolution C 1s near-edge x-ray-absorption fine-structure (NEXAFS) spectra of the C{sub 6}-ring-containing molecules benzene (C{sub 6}H{sub 6}), 1,3- and 1,4-cyclohexadiene (C{sub 6}H{sub 8}), cyclohexene (C{sub 6}H{sub 10}), cyclohexane (C{sub 6}H{sub 12}), styrene (C{sub 8}H{sub 8}), and ethylbenzene (C{sub 8}H{sub 10}) which allow us to examine the gradual development of delocalization of the corresponding {pi} electron systems. Due to the high experimental resolution, vibrational progressions can be partly resolved in the spectra. The experimental spectra are compared with theoretical NEXAFS spectra obtained from density-functional theory calculations where electronic final-state relaxation is accounted for. The comparison yields very good agreement between theoretical spectra and experimental results. In all cases, the spectra can be described by excitations to {pi}*- and {sigma}*-type final-state orbitals with valence character, while final-state orbitals of Rydberg character make only minor contributions. The lowest C 1s{yields}1{pi}* excitation energy is found to agree in the (experimental and theoretical) spectra of all molecules except for 1,3-cyclohexadiene (C{sub 6}H{sub 8}) where an energy smaller by about 0.6 eV is obtained. The theoretical analysis can explain this result by different binding properties of this molecule compared to the others.

  15. Morphological and spectroscopic investigation of the behavior of permanent iridium modifier deposited on pyrolytic graphite coated and zirconium treated platforms in electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Slaveykova, Vera I.; Lampugnani, Leonardo; Tsalev, Dimiter L.; Sabbatini, L.

    1997-12-01

    In order to better characterise a permanent modifier based on iridium deposited on zirconium or tungsten treated platforms of transversely heated graphite atomizer, and to gain additional information about its chemical behavior directed to an eventual further optimization, a series of experiments were carried out, both by surface techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS or ESCA) and X-ray fluorescence (XRF) and by electrothermal atomic absorption spectrometry on the iridium release from unmodified and various other modified pyrolytic graphite platforms. Special attention was paid to the influence of the amount of iridium, zirconium carbide coating of the platform surface and the presence of citric acid on the iridium vaporization during pyrolysis and atomization. The processes of iridium losses during pyrolysis and atomization and peak maximum alignment depend on the amount of the iridium deposited on the pyrolytic graphite coated platforms in the presence of nitric acid. A fractional order of release which suggests an atom vaporization from the surface or edges of the iridium islands was estimated. In the presence of citric acid, mass independence and zero order of the atom release were found. The zirconium treatment of the platform results in change of the spatial distribution of iridium and hence its vaporization. Vaporization temperatures as high as 2100°C, and first order of the process of atom generation were obtained. While it was possible to study the iridium atomization from uncoated and zirconium coated surfaces, evidencing a different order for the release process, the same was not possible for the tungsten coated platforms due to an 'overstabilization' that brought the iridium atomization temperature out of the working range of the instrument used. The different chemical behavior of tungsten and zirconium was also confirmed by XPS investigations. With tungsten, evidence of both WC and WO bonding

  16. Dimeric and polymeric mercury(II) complexes of 1-methyl-1,2,3,4-tetrazole-5-thiol: Synthesis, crystal structure, spectroscopic characterization, and thermal analyses

    NASA Astrophysics Data System (ADS)

    Taheriha, Mohammad; Ghadermazi, Mohammad; Amani, Vahid

    2016-03-01

    Two-dimensional coordination polymer of [Hg(μ3-mmtz)2]n (1) and centrosymmetric dinuclear complexes of {[H2en][Hg2(mmtz)4(μ-Br)2]} (2) and {[H2en][Hg2(mmtz)4(μ-I)2]} (3) (where Hmmtz is 1-methyl-1,2,3,4-tetrazole-5-thiol and en is ethylene diamine) were synthesized from the reaction of Hmmtz and en with HgCl2, HgBr2 and HgI2, respectively, in CH3OH. Complex 1 was also synthesized from the reaction of Hmmtz and en with HgX2 (X = OAc and SCN) in CH3OH. These three complexes were thoroughly characterized by elemental analysis (CHN), thermal gravimetric analysis (TGA), differential thermal analyses (DTA), infrared, UV-vis, 1H NMR, and luminescence spectroscopy, and their structures were determined by single-crystal X-ray diffraction.

  17. Spectroscopic Low Coherence Interferometry

    NASA Astrophysics Data System (ADS)

    Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.

    Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.

  18. Spectroscopic studies, thermal analyses and biological evaluation of new V(IV), Zr(IV) and U(VI) moxifloxacin complexes

    NASA Astrophysics Data System (ADS)

    Sadeek, Sadeek A.; El-Shwiniy, Walaa H.; Zordok, Wael A.; Kotb, Essam

    2011-12-01

    The synthesis and characterization of the new solid complexes [VO(MOX) 2H 2O]SO 4·11H 2O, [ZrO(MOX) 2Cl]Cl·15H 2O and [UO 2(MOX) 3](NO 3) 2·3H 2O formed in the interaction of moxifloxacin (MOX) with VOSO 4·H 2O, ZrOCl 2·8H 2O and UO 2(NO 3) 2·6H 2O in methanol and acetone as a solvents at room temperature were reported. The isolated solid complexes have been characterized with melting points, elemental analysis, molar conductance, magnetic moments studies, spectral (UV-Visible, IR and 1HNMR) as well as thermal analyses (TGA and DTG). The results support the formation of the complexes and indicate that moxifloxacin reacts as a bidentate ligand chelate to the metal ion through the pyridone oxygen and one carboxylato oxygen. The kinetic parameters of thermogravimetric (TGA) and its differential (DTG), such as activation energies, E*, enthalpies, Δ H*, entropies, Δ S* and Gibbs free energies, Δ G*, have been evaluated by using Coats-Redfern (CR) and Horowitz-Metzeger (HM) methods. The proposed structure of the ligand and their complexes were detected by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The bond stretching force constant and length of the U dbnd O for the [UO 2(MOX) 3](NO 3) 2·3H 2O complex were calculated. The antibacterial activity of the free moxifloxacin ligand and their metal complexes have been tested against some selected bacterial strains such as: Streptococcus aureus K1, Bacillus subtilis K22, Brevibacterium otitidis K76, Escherichia coli K32, Pseudomonas aeruginosa SW1 and Klebsiella oxytoca K42. The complexes showed good antibacterial effect to the selected bacterial strains as compared to the free ligand and Zr(IV) complex is very highly significant compared with the other two complexes.

  19. X-ray Absorption and Emission Spectroscopic Studies of [L2Fe2S2](n) Model Complexes: Implications for the Experimental Evaluation of Redox States in Iron-Sulfur Clusters.

    PubMed

    Kowalska, Joanna K; Hahn, Anselm W; Albers, Antonia; Schiewer, Christine E; Bjornsson, Ragnar; Lima, Frederico A; Meyer, Franc; DeBeer, Serena

    2016-05-01

    Herein, a systematic study of [L2Fe2S2](n) model complexes (where L = bis(benzimidazolato) and n = 2-, 3-, 4-) has been carried out using iron and sulfur K-edge X-ray absorption (XAS) and iron Kβ and valence-to-core X-ray emission spectroscopies (XES). These data are used as a test set to evaluate the relative strengths and weaknesses of X-ray core level spectroscopies in assessing redox changes in iron-sulfur clusters. The results are correlated to density functional theory (DFT) calculations of the spectra in order to further support the quantitative information that can be extracted from the experimental data. It is demonstrated that due to canceling effects of covalency and spin state, the information that can be extracted from Fe Kβ XES mainlines is limited. However, a careful analysis of the Fe K-edge XAS data shows that localized valence vs delocalized valence species may be differentiated on the basis of the pre-edge and K-edge energies. These findings are then applied to existing literature Fe K-edge XAS data on the iron protein, P-cluster, and FeMoco sites of nitrogenase. The ability to assess the extent of delocalization in the iron protein vs the P-cluster is highlighted. In addition, possible charge states for FeMoco on the basis of Fe K-edge XAS data are discussed. This study provides an important reference for future X-ray spectroscopic studies of iron-sulfur clusters. PMID:27097289

  20. Interaction of vanadium (IV) solvates (L) with second-generation fluoroquinolone antibacterial drug ciprofloxacin: spectroscopic, structure, thermal analyses, kinetics and biological evaluation (L=An, DMF, Py and Et3N).

    PubMed

    Zordok, Wael A

    2014-08-14

    The preparation and characterization of the new solid complexes [VO(CIP)2L]SO4⋅nH2O, where L=aniline (An), dimethylformamide (DMF), pyridine (Py) and triethylamine (Et3N) in the reaction of ciprofloxacin (CIP) with VO(SO4)2·2H2O in ethanol. The isolated complexes have been characterized with their melting points, elemental analysis, IR spectroscopy, magnetic properties, conductance measurements, UV-Vis. and (1)H NMR spectroscopic methods and thermal analyses. The results supported the formation of the complexes and indicated that ciprofloxacin reacts as a bidentate ligand bound to the vanadium ion through the pyridone oxygen and one carboxylato oxygen. The activation energies, E(*); entropies, ΔS(*); enthalpies, ΔH(*); Gibbs free energies, ΔG(*), of the thermal decomposition reactions have been derived from thermo gravimetric (TGA) and differential thermo gravimetric (DTG) curves, using Coats-Redfern and Horowitz-Metzeger methods. The lowest energy model structure of each complex has been proposed by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The ligand and their metal complexes were also evaluated for their antibacterial activity against several bacterial species, such as Bacillus Subtilis (B. Subtilis), Staphylococcus aureus (S. aureus), Nesseria Gonorrhoeae (N. Gonorrhoeae), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli). PMID:24762540

  1. Interaction of vanadium (IV) solvates (L) with second-generation fluoroquinolone antibacterial drug ciprofloxacin: Spectroscopic, structure, thermal analyses, kinetics and biological evaluation (L = An, DMF, Py and Et3N)

    NASA Astrophysics Data System (ADS)

    Zordok, Wael A.

    2014-08-01

    The preparation and characterization of the new solid complexes [VO(CIP)2L]SO4ṡnH2O, where L = aniline (An), dimethylformamide (DMF), pyridine (Py) and triethylamine (Et3N) in the reaction of ciprofloxacin (CIP) with VO(SO4)2·2H2O in ethanol. The isolated complexes have been characterized with their melting points, elemental analysis, IR spectroscopy, magnetic properties, conductance measurements, UV-Vis. and 1H NMR spectroscopic methods and thermal analyses. The results supported the formation of the complexes and indicated that ciprofloxacin reacts as a bidentate ligand bound to the vanadium ion through the pyridone oxygen and one carboxylato oxygen. The activation energies, E*; entropies, ΔS*; enthalpies, ΔH*; Gibbs free energies, ΔG*, of the thermal decomposition reactions have been derived from thermo gravimetric (TGA) and differential thermo gravimetric (DTG) curves, using Coats-Redfern and Horowitz-Metzeger methods. The lowest energy model structure of each complex has been proposed by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The ligand and their metal complexes were also evaluated for their antibacterial activity against several bacterial species, such as Bacillus Subtilis (B. Subtilis), Staphylococcus aureus (S. aureus), Nesseria Gonorrhoeae (N. Gonorrhoeae), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli).

  2. USEPA METHOD STUDY 35 - SW-846 METHOD 3005, ACID DIGESTION OF WATERS FOR TOTAL RECOVERABLE OR DISSOLVED METALS FOR ANALYSES BY FLAME ATOMIC ABSORPTION SPECTROSCOPY

    EPA Science Inventory

    An interlaboratory collaborative study was conducted to determine the precision and bias (recovery) of Solid Waste (SW) Method 3005 for the analysis of 21 elements in ground water. SW Method 3005 is entitled, "Acid Digestion of Waters for Total Recoverable Metals for Analyses by ...

  3. USEPA (United States Environmental Protection Agency) method study 7. Analyses for trace elements in water by atomic absorption spectroscopy (direct aspiration) and colorimetry. Final report

    SciTech Connect

    Winter, J.A.; Britton, P.W.

    1986-06-01

    The report describes a study of ten elements: aluminum, arsenic, cadmium, chromium, copper, iron, lead, manganese, selenium and zinc, at trace levels in water. Six sample concentrates, each containing the ten trace elements, were sealed in glass ampuls, verified as homogeneous and stable over time, and provided to the analysts with instructions for sample preparation and analyses. Mean recovery, overall standard deviation, and single-analyst standard deviations were calculated for each element at each concentration and for the two water types.

  4. Macroscopic and spectroscopic analysis of lanthanide adsorption to bacterial cells

    NASA Astrophysics Data System (ADS)

    Ngwenya, Bryne T.; Mosselmans, J. Fred W.; Magennis, Marisa; Atkinson, Kirk D.; Tourney, Janette; Olive, Valerie; Ellam, Robert M.

    2009-06-01

    This study was designed to combine surface complexation modelling of macroscopic adsorption data with X-ray Absorption Spectroscopic (XAS) measurements to identify lanthanide sorption sites on the bacterial surface. The adsorption of selected representatives for light (La and Nd), middle (Sm and Gd) and heavy (Er and Yb) lanthanides was measured as a function of pH, and biomass samples exposed to 4 mg/L lanthanide at pH 3.5 and 6 were analysed using XAS. Surface complexation modelling was consistent with the light lanthanides adsorbing to phosphate sites, whereas the adsorption of middle and heavy lanthanides could be modelled equally well by carboxyl and phosphate sites. The existence of such mixed mode coordination was confirmed by Extended X-ray Absorption Fine Structure (EXAFS) analysis, which was also consistent with adsorption to phosphate sites at low pH, with secondary involvement of carboxyl sites at high adsorption density (high pH). Thus, the two approaches yield broadly consistent information with regard to surface site identity and lanthanide coordination environment. Furthermore, spectroscopic analysis suggests that coordination to phosphate sites is monodentate at the metal/biomass ratios used. Based on the best-fitting p Ka site, we infer that the phosphate sites are located on N-acetylglucosamine phosphate, the most likely polymer on gram-negative cells with potential phosphate sites that deprotonate around neutral pH.

  5. Resolving Spectral Lines with a Periscope-Type DVD Spectroscope

    ERIC Educational Resources Information Center

    Wakabayashi, Fumitaka

    2008-01-01

    A new type of DVD spectroscope, the periscope type, is described and the numerical analysis of the observed emission and absorption spectra is demonstrated. A small and thin mirror is put inside and an eighth part of a DVD is used as a grating. Using this improved DVD spectroscope, one can observe and photograph visible spectra more easily and…

  6. Joint X-ray absorption and far infrared spectroscopic studies on zeolite surfaces exchange and siting of copper ions and their redox behavior during NO decomposition in zeolite ZSM-5

    NASA Astrophysics Data System (ADS)

    Esemann, H.; Förster, H.

    1999-05-01

    Far infrared (FIR) and X-ray absorption spectroscopy (XAS) assisted by computer modelling were tested for their aptitude to study ion exchange, cation siting, NO adsorption and redox behavior of CuZSM-5.

  7. A spectroscopic study of uranium(VI) interaction with magnetite

    NASA Astrophysics Data System (ADS)

    Aamrani, S. El; Giménez, J.; Rovira, M.; Seco, F.; Grivé, M.; Bruno, J.; Duro, L.; de Pablo, J.

    2007-08-01

    The uranium sorbed onto commercial magnetite has been characterized by using two different spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS). Magnetite samples have been put in contact with uranium(VI) solutions in conditions in which a high uranium uptake is expected. After several days, the magnetite surface has been analysed by XPS and EXAFS. The XPS results obtained are not conclusive regarding the uranium oxidation state in the magnetite surface. On the other hand, the results obtained with the EXAFS technique show that the uranium-magnetite sample spectrum has characteristics from both the UO 2 and schoepite spectra, e.g. a relatively high coordination number of equatorial oxygens and two axial oxygens, respectively. These results would indicate that the uranium sorbed onto magnetite would be a mixture of uranium(IV) and uranium(VI).

  8. Mn L{sub 2,3}-edge X-ray absorption spectroscopic studies on charge-discharge mechanism of Li{sub 2}MnO{sub 3}

    SciTech Connect

    Kubobuchi, Kei; Mogi, Masato; Imai, Hideto; Ikeno, Hidekazu; Tanaka, Isao; Mizoguchi, Teruyasu

    2014-02-03

    The redox reaction of Mn in Li{sub 2}MnO{sub 3} was studied by X-ray absorption spectroscopy and ab initio multiplet calculation. Associated with the de-intercalation of Li-ion, small but clear spectral changes were observed in Mn-L{sub 2,3} X-ray absorption near edge structure (XANES). The systematic ab initio multiplet calculations of Mn-L{sub 2,3} XANES revealed that the spectral changes in the experiment could not simply be ascribed to the change of the valency from Mn{sup 4+} to Mn{sup 5+} but can be explained well by the changes of local atomic structures around Mn{sup 4+} due to the Li de-intercalation. Our results suggest that the electronic state of oxygen should change during charging in Li{sub 2}MnO{sub 3}.

  9. The HITRAN2012 molecular spectroscopic database

    NASA Astrophysics Data System (ADS)

    Rothman, L. S.; Gordon, I. E.; Babikov, Y.; Barbe, A.; Chris Benner, D.; Bernath, P. F.; Birk, M.; Bizzocchi, L.; Boudon, V.; Brown, L. R.; Campargue, A.; Chance, K.; Cohen, E. A.; Coudert, L. H.; Devi, V. M.; Drouin, B. J.; Fayt, A.; Flaud, J.-M.; Gamache, R. R.; Harrison, J. J.; Hartmann, J.-M.; Hill, C.; Hodges, J. T.; Jacquemart, D.; Jolly, A.; Lamouroux, J.; Le Roy, R. J.; Li, G.; Long, D. A.; Lyulin, O. M.; Mackie, C. J.; Massie, S. T.; Mikhailenko, S.; Müller, H. S. P.; Naumenko, O. V.; Nikitin, A. V.; Orphal, J.; Perevalov, V.; Perrin, A.; Polovtseva, E. R.; Richard, C.; Smith, M. A. H.; Starikova, E.; Sung, K.; Tashkun, S.; Tennyson, J.; Toon, G. C.; Tyuterev, Vl. G.; Wagner, G.

    2013-11-01

    This paper describes the status of the 2012 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2008 and its updates during the intervening years. The HITRAN molecular absorption compilation is comprised of six major components structured into folders that are freely accessible on the internet. These folders consist of the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, ultraviolet spectroscopic parameters, aerosol indices of refraction, collision-induced absorption data, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, and validity. Molecules and isotopologues have been added that address the issues of atmospheres beyond the Earth. Also discussed is a new initiative that casts HITRAN into a relational database format that offers many advantages over the long-standing sequential text-based structure that has existed since the initial release of HITRAN in the early 1970s.

  10. Phenanthro[4,5-fgh]quinoxaline-Fused Subphthalocyanines: Synthesis, Structure, and Spectroscopic Characterization.

    PubMed

    Pan, Houhe; Liu, Wenbo; Wang, Chiming; Wang, Kang; Jiang, Jianzhuang

    2016-07-01

    A series of four phenanthro[4,5-fgh]quinoxaline-fused subphthalocyanine derivatives 0-3 containing zero, one, two, and three phenanthro[4,5-fgh]quinoxaline moieties, respectively, were isolated from the mixed cyclotrimerization reaction of 2,9-di-tert-butylphenanthro[4,5-fgh]quinoxaline-5,6-dicarbonitrile with 4,5-bis(2,6-diisopropylphenoxy)phthalonitrile and characterized by a series of spectroscopic methods including MALDI-TOF mass, (1) H NMR, electronic absorption, magnetic circular dichroism (MCD), and fluorescence spectroscopy. The molecular structures for the compounds 0 and 2 were clearly revealed on the basis of single-crystal X-ray diffraction analysis. Their electrochemical properties were also studied by cyclic voltammetry. In particular, theoretical calculations in combination with the electronic absorption and electrochemical analyses revealed the significant influence of the fused-phenanthro[4,5-fgh]quinoxaline units on the electronic structures. PMID:27123546

  11. Reflection-absorption infrared spectroscopic study on a CuO X/SiO 2 model catalyst prepared by spin-coating on a SiO 2/W/Si(100) buried metal substrate

    NASA Astrophysics Data System (ADS)

    Fukui, Ken-ichi; Oshima, Itaru; Oosterbeek, Heiko; Iwasawa, Yasuhiro

    1999-01-01

    CuO X particles were deposited by spin-coating on a SiO 2(50 nm)/W(70 nm)/Si(100) buried metal substrate using 2-propanol solution of a Cu precursor followed by oxidation. The CuO X/SiO 2/W/Si model catalyst was used to detect vibrational modes of submonolayer adsorbates by reflection-absorption infrared spectroscopy (RAIRS). During methanol reaction on CuO X/SiO 2/W/Si, RAIR spectra showed that methoxy species was formed on CuO X particles and spilt over to the SiO 2 substrate, replacing hydroxyl species.

  12. Dipeptide absorption in man

    PubMed Central

    Hellier, M. D.; Holdsworth, C. D.; McColl, I.; Perrett, D.

    1972-01-01

    A quantitative perfusion method has been used to study intestinal absorption of two dipeptides—glycyl-glycine and glycyl-l-alanine—in normal subjects. In each case, the constituent amino acids were absorbed faster when presented as dipeptides than as free amino acids, suggesting intact dipeptide transport. During absorption constituent amino acids were measured within the lumen and it is suggested that these represent amino acids which have diffused back to the lumen after absorption as dipeptide. Portal blood analyses during absorption of a third dipeptide, glycyl-l-lysine, have shown that this dipeptide, known to be transported intact from the intestinal lumen, is hydrolysed to its constitutent amino acids before it reaches portal venous blood. PMID:4652039

  13. Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid

    NASA Astrophysics Data System (ADS)

    Świsłocka, Renata

    The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and 1H and 13C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris.

  14. Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid.

    PubMed

    Świsłocka, Renata

    2013-01-01

    The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and (1)H and (13)C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris. PMID:22369898

  15. Cholesterol absorption.

    PubMed

    Ostlund, Richard E

    2002-03-01

    Cholesterol absorption is a key regulatory point in human lipid metabolism because it determines the amount of endogenous biliary as well as dietary cholesterol that is retained, thereby influencing whole body cholesterol balance. Plant sterols (phytosterols) and the drug ezetimibe reduce cholesterol absorption and low-density lipoprotein cholesterol in clinical trials, complementing the statin drugs, which inhibit cholesterol biosynthesis. The mechanism of cholesterol absorption is not completely known but involves the genes ABC1, ABCG5, and ABCG8, which are members of the ATP-binding cassette protein family and appear to remove unwanted cholesterol and phytosterols from the enterocyte. ABC1 is upregulated by the liver X (LXR) and retinoid X (RXR) nuclear receptors. Acylcholesterol acytransferase-2 is an intestinal enzyme that esterifies absorbed cholesterol and increases cholesterol absorption when dietary intake is high. New clinical treatments based on better understanding of absorption physiology are likely to substantially improve clinical cholesterol management in the future. PMID:17033296

  16. The HITRAN 2008 Molecular Spectroscopic Database

    NASA Technical Reports Server (NTRS)

    Rothman, Laurence S.; Gordon, Iouli E.; Barbe, Alain; Benner, D. Chris; Bernath, Peter F.; Birk, Manfred; Boudon, V.; Brown, Linda R.; Campargue, Alain; Champion, J.-P.; Chance, Kelly V.; Coudert, L. H.; Sung, K.; Toth, R. A.

    2009-01-01

    This paper describes the status of the 2008 edition of the HITRAN molecular spectroscopic database. The new edition is the first official public release since the 2004 edition, although a number of crucial updates had been made available online since 2004. The HITRAN compilation consists of several components that serve as input for radiative-transfer calculation codes: individual line parameters for the microwave through visible spectra of molecules in the gas phase; absorption cross-sections for molecules having dense spectral features, i.e., spectra in which the individual lines are not resolved; individual line parameters and absorption cross sections for bands in the ultra-violet; refractive indices of aerosols, tables and files of general properties associated with the database; and database management software. The line-by-line portion of the database contains spectroscopic parameters for forty-two molecules including many of their isotopologues.

  17. Spectroscopic studies of copper enzymes

    SciTech Connect

    Dooley, D.M.; Moog, R.; Zumft, W.; Koenig, S.H.; Scott, R.A.; Cote, C.E.; McGuirl, M.

    1986-05-01

    Several spectroscopic methods, including absorption, circular dichroism (CD), magnetic CD (MCD), X-ray absorption, resonance Raman, EPR, NMR, and quasi-elastic light-scattering spectroscopy, have been used to probe the structures of copper-containing amine oxidases, nitrite reductase, and nitrous oxide reductase. The basic goals are to determine the copper site structure, electronic properties, and to generate structure-reactivity correlations. Collectively, the results on the amine oxidases permit a detailed model for the Cu(II) sites in these enzymes to be constructed that, in turn, rationalizes the ligand-binding chemistry. Resonance Raman spectra of the phenylhydrazine and 2,4-dinitrophenyl-hydrazine derivatives of bovine plasma amine oxidase and models for its organic cofactor, e.g. pyridoxal, methoxatin, are most consistent with methoxatin being the intrinsic cofactor. The structure of the Cu(I) forms of the amine oxidases have been investigated by X-ray absorption spectroscopy (XAS); the copper coordination geometry is significantly different in the oxidized and reduced forms. Some anomalous properties of the amine oxidases in solution are explicable in terms of their reversible aggregation, which the authors have characterized via light scattering. Nitrite and nitrous oxide reductases display several novel spectral properties. The data suggest that new types of copper sites are present.

  18. Spectroscopic investigations of dithienyl polyenes

    NASA Astrophysics Data System (ADS)

    Cooper, Thomas M.; Sowards, Laura A.; Natarajan, Lalgudi V.; Kirkpatrick, Sean M.; Chandra, Suresh; McLean, Daniel G.; Spangler, Charles W.

    1999-10-01

    To understand the photophysics of nonlinear absorbers, we have investigated the photophysics of a series of di(2- thienyl-3,3',4,4'-butyl)polyenes. Spectroscopic measurements, including UV/Vis, fluorescence, fluorescence lifetimes, fluorescence quantum yields, triplet state lifetime, solvent effects and two-photon absorption coefficient were obtained as a function of the number of double bonds (n equals 1 - 5). Trends in the data reflected the ordering, energy gap between and mixing of 1Bu* and 1Ag* excited state configurations. We investigated the solvatochromism of a series of (alpha) ,(omega) -di(2- dithienyl 3,3',4,4'-butyl) polyenes. Absorption (n equals 1 - 5 double bonds) were collected in a series of aprotic solvents. The absorption energy dispersion effect sensitivity increased smoothly with n, reaching asymptotic behavior as n approached 5. The emission energy had less solvent sensitivity, giving evidence for a polar 1Bu* absorbing state and a nonpolar 1Ag* emitting state. We observed sensitivity of the absorbing and emitting states to solute-solvent dipole-dipole interactions, suggesting the dithienyl polyenes had a polar syn ground state conformation.

  19. Sulfur X-Ray Absorption And Vibrational Spectroscopic Study of Sulfur Dioxide, Sulfite, And Sulfonate Solutions And of the Substituted Sulfonate Ions X(3)CSO(3-)(X = H, Cl, F)

    SciTech Connect

    Risberg, E.Damian; Eriksson, L.; Mink, J.; Pettersson, L.G.M.; Skripkin, M.Yu.; Sandstrom, M.

    2009-06-02

    Sulfur K-edge X-ray absorption near-edge structure (XANES) spectra have been recorded and the S(1s) electron excitations evaluated by means of density functional theory-transition potential (DFT-TP) calculations to provide insight into the coordination, bonding, and electronic structure. The XANES spectra for the various species in sulfur dioxide and aqueous sodium sulfite solutions show considerable differences at different pH values in the environmentally important sulfite(IV) system. In strongly acidic (pH < {approx}1) aqueous sulfite solution the XANES spectra confirm that the hydrated sulfur dioxide molecule, SO{sub 2}(aq), dominates. The theoretical spectra are consistent with an OSO angle of {approx}119{sup o} in gas phase and acetonitrile solution, while in aqueous solution hydrogen bonding reduces the angle to {approx}116{sup o}. The hydration affects the XANES spectra also for the sulfite ion, SO{sub 3}{sup 2-}. At intermediate pH (4) the two coordination isomers, the sulfonate (HSO{sub 3{sup -}}) and hydrogen sulfite (SO{sub 3}H{sup -}) ions with the hydrogen atom coordinated to sulfur and oxygen, respectively, could be distinguished with the ratio HSO{sub 3{sup -}}:SO{sub 3}H{sup -} about 0.28:0.72 at 298 K. The relative amount of HSO{sub 3{sup -}} increased with increasing temperature in the investigated range from 275 to 343 K. XANES spectra of sulfonate, methanesulfonate, trichloromethanesulfonate, and trifluoromethanesulfonate compounds, all with closely similar S-O bond distances in tetrahedral configuration around the sulfur atom, were interpreted by DFT-TP computations. The energy of their main electronic transition from the sulfur K-shell is about 2478 eV. The additional absorption features are similar when a hydrogen atom or an electron-donating methyl group is bonded to the -SO{sub 3} group. Significant changes occur for the electronegative trichloromethyl (Cl{sub 3}C-) and trifluoromethyl (F{sub 3}C-) groups, which strongly affect the

  20. Integral Field Spectroscopy of AGN Absorption Outflows: Mrk 509 and IRAS F04250-5718

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Arav, Nahum; Rupke, David S. N.

    2015-11-01

    Ultraviolet (UV) absorption lines provide abundant spectroscopic information enabling the probe of the physical conditions in active galactic nucleus (AGN) outflows, but the outflow radii (and the energetics consequently) can only be determined indirectly. We present the first direct test of these determinations using integral field unit (IFU) spectroscopy. We have conducted Gemini IFU mapping of the ionized gas nebulae surrounding two AGNs, whose outflow radii have been constrained by UV absorption line analyses. In Mrk 509, we find a quasi-spherical outflow with a radius of 1.2 kpc and a velocity of ˜290 km s-1, while IRAS F04250-5718 is driving a biconical outflow extending out to 2.9 kpc, with a velocity of ˜580 km s-1 and an opening angle of ˜70°. The derived mass flow rate ˜5 and >1 M⊙ yr-1, respectively, and the kinetic luminosity ≳1 × 1041 erg s-1 for both. Adopting the outflow radii and geometric parameters measured from IFU, absorption line analyses would yield mass flow rates and kinetic luminosities in agreement with the above results within a factor of ˜2. We conclude that the spatial locations, kinematics, and energetics revealed by this IFU emission-line study are consistent with pre-existing UV absorption line analyses, providing a long-awaited direct confirmation of the latter as an effective approach for characterizing outflow properties.

  1. Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveal a role for the disordered C-terminal arm in metal trafficking

    PubMed Central

    Banaszak, Katarzyna; Martin-Diaconescu, Vlad; Bellucci, Matteo; Zambelli, Barbara; Rypniewski, Wojciech; Maroney, Michael J.; Ciurli, Stefano

    2012-01-01

    The survival and growth of the pathogen Helicobacter pylori in the gastric acidic environment is ensured by the activity of urease, an enzyme containing two essential Ni2+ ions in the active site. The metallo-chaperone UreE facilitates in vivo Ni2+ insertion into the apo-enzyme. Crystals of apo-HpUreE and its Ni2+ and Zn2+ bound forms were obtained from protein solutions in the absence and presence of the metal ions. The crystal structures of the homodimeric protein, determined at 2.00 Å (apo), 1.59 Å (Ni) and 2.52 Å (Zn) resolution, show the conserved proximal and solvent-exposed His102 residues from two adjacent monomers invariably involved in metal binding. The C-terminal regions of the apo-protein are disordered in the crystal, but acquire significant ordering in the presence of the metal ions due to the binding of His152. The analysis of X-ray absorption spectral data obtained on solutions of Ni2+- and Zn2+-HpUreE provided accurate information of the metal ion environment in the absence of solid-state effects. These results reveal the role of the histidine residues at the protein C-terminus in metal ion binding, and the mutual influence of protein framework and metal ion stereo-electronic properties in establishing coordination number and geometry leading to metal selectivity. PMID:22010876

  2. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  3. Picosecond flash spectroscopic studies on ultraviolet stabilizers and stabilized polymers

    NASA Technical Reports Server (NTRS)

    Scott, G. W.

    1982-01-01

    Spectroscopic and excited state decay kinetics are reported for monomeric and polymeric forms of ultraviolet stabilizers in the 2-(2'-hydroxyphenyl)-benzotriazole and 2-hydroxybenzophenone classes. For some of these molecules in various solvents at room temperature, (1) ground state absorption spectra, (2) emission spectra, (3) picosecond time-resolved transient absorption spectra, (4) ground state absorption recovery kinetics, (5) emission kinetics, and (6) transient absorption kinetics are reported. In the solid state at low temperatures, emission spectra and their temperature dependent kinetics up to approximately 200K as well as, in one case, the 12K excitation spectra of the observed dual emission are also reported.

  4. Electronic and molecular structures of the members of the electron transfer series [Cr(tbpy)3]n (n = 3+, 2+, 1+, 0): an X-ray absorption spectroscopic and density functional theoretical study.

    PubMed

    Scarborough, Christopher C; Sproules, Stephen; Weyhermüller, Thomas; DeBeer, Serena; Wieghardt, Karl

    2011-12-19

    The electron transfer series of complexes [Cr((t)bpy)(3)](n)(PF(6))(n) (n = 3+, 2+, 1+, 0 (1-4)) has been synthesized and the molecular structures of 1, 2, and 3 have been determined by single-crystal X-ray crystallography; the structure of 4 has been investigated using extended X-ray absorption fine structure (EXAFS) analysis. Magnetic susceptibility measurements (4-300 K) established an S = 3/2 ground state for 1, an S = 1 ground state for 2, an S = 1/2 ground state for 3, and an S = 0 ground state for 4. The electrochemistry of this series in CH(3)CN solution exhibits three reversible one-electron transfer waves. UV-vis/NIR spectra and Cr K-edge X-ray absorption spectra (XAS) are reported. The same experimental techniques have been applied for [Cr(III)(tacn)(2)]Br(3)·5H(2)O (5) and [Cr(II)(tacn)(2)]Cl(2) (6), which possess an S = 3/2 and an S = 2 ground state, respectively (tacn = 1,4,7-triazacyclononane, a tridentate, pure σ-donor ligand). The Cr K-edge XAS spectra of the corresponding complexes K(4)[Cr(II)(CN)(6)]·10H(2)O (S = 1) (7) and K(3)[Cr(III)(CN)(6)] (S = 3/2) (8) have also been recorded. All complexes have been studied computationally with density functional theory (DFT) using the B3LYP functional. The molecular and electronic structures of the anionic members of the series [Cr(bpy)(3)](1-,2-,3-) have also been calculated. It is unequivocally shown that all members of the electron transfer series 1-4 and [Cr(bpy)(3)](n) (n = 3+, 2+, 1+, 0, 1-, 2, 3-) possess a central Cr(III) ion ((t(2g))(3), S = 3/2). The three N,N'-coordinated neutral (bpy(0)) ligands in the trication 1 and [Cr(III)(bpy)(3)](3+) are one-electron reduced in a stepwise fashion to localized one, two, and three π-radical anions (bpy(•))(1-) in the dicationic, monocationic, and neutral species, respectively. Complexes 2 and [Cr(bpy)(3)](2+) cannot be described as low-spin Cr(II) species; they are in fact best described as [Cr(III)((t)bpy(•))((t)bpy(0))(2)](2+) and [Cr

  5. Thermodynamic Modeling of Poorly Complexing Metals in Concentrated Electrolyte Solutions: An X-Ray Absorption and UV-Vis Spectroscopic Study of Ni(II) in the NiCl2-MgCl2-H2O System

    PubMed Central

    Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

    2015-01-01

    Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at RNi-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg-1 NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg-1 NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system. PMID:25885410

  6. The Uptake and Fate of Vanadyl Ion in Ascidian Blood Cells and A Detailed Hypothesis for the Mechanism and Location of Biological Vanadium Reduction: A Visible and X-Ray Absorption Spectroscopic Study

    PubMed Central

    Frank, Patrick; Carlson, Elaine J.; Carlson, Robert M. K.; Hedman, Britt; Hodgson, Keith O.

    2010-01-01

    Vanadium K-edge x-ray absorption spectroscopy (XAS) has been used to track the uptake and fate of VO2+ ion in blood cells from Ascidia ceratodes, following exposure to dithiothreitol (DTT) or to DTT plus VO2+. The full range of endogenous vanadium was queried by fitting the XAS of blood cells with the XAS spectra of model vanadium complexes. In cells exposed only to DTT, ~0.4% of a new V(III) species was found in a site similar to Na[V(edta)(H2O)]. With exposure to DTT and VO2+, average intracellular [VO(aq)]2+ increased from 3% to 5%, and 6% of a new complexed form of vanadyl ion appeared evidencing a ligand array similar to [VO(edta)]2−. At the same time, the relative ratio of blood cell [V(H2O)6]3+ increased at the expense of [V(H2O)5(SO4)]+ in a manner consistent with a significant increase in endogenous acidity. In new UV/visible experiments, VO2+ could be reduced to 7-coordinate [V(nta)(H2O)3] or [V(nta)(ida)]2−with cysteine methyl ester in pH 6.5 solution. Ascorbate reduced [VO(edta)]2− to 7-coordinate [V(edta)(H2O)]−, while [VO(trdta)]2− was unreactive. These results corroborate the finding that the reductive EMF of VO2+ is increased by the availability of a 7-coordinate V(III) product. Finally a new and complete hypothesis is proposed for an ascidian vanadate reductase. The structure of the enzyme active site, the vanadate-vanadyl-vanadic reduction mechanism, the cellular locale, and elements of the regulatory machinery governing the biological reduction of vanadate and vanadyl ion by ascidians are all predicted. Together these constitute the new field of vanadium redox enzymology. PMID:18234345

  7. Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Debraj; Singh, Sachin Kumar; Sharma, Poornima; Mishra, Hirdyesh; Unnikrishnan, V. K.; Singh, Bachcha; Singh, Ranjan K.

    2016-02-01

    Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations.

  8. Terahertz broadband spectroscopic investigations of amino acid

    NASA Astrophysics Data System (ADS)

    Zhu, De-chong; Zhang, Liang-liang; Zhong, Hua; Zhang, Cun-lin

    2011-08-01

    We present an experimental terahertz (THz) spectroscopic investigation of amino acid using an air-breakdown-coherent detection (ABCD) system. The strong and ultra-broadband (0.1 to 10THz) terahertz radiations generated by two-color laser induced air plasma and measured by coherent heterodyne detection. The broadband THz reflection spectra of L-Lysine (C6H14N2O2) and L-Arginine (C6H14N2O2) are obtained. To solve the phase-retrieval problem in RTDS, the absorption signatures of the materials are extracted directly from the first derivative of the relative reflectance with respect to frequency. The absorption features of the two amino acids are characterized in the 0.5~6 THz region. It is found that both the two amino acids have an absorption peak at 1.10 THz.

  9. Calibration method for spectroscopic systems

    DOEpatents

    Sandison, David R.

    1998-01-01

    Calibration spots of optically-characterized material placed in the field of view of a spectroscopic system allow calibration of the spectroscopic system. Response from the calibration spots is measured and used to calibrate for varying spectroscopic system operating parameters. The accurate calibration achieved allows quantitative spectroscopic analysis of responses taken at different times, different excitation conditions, and of different targets.

  10. Calibration method for spectroscopic systems

    DOEpatents

    Sandison, D.R.

    1998-11-17

    Calibration spots of optically-characterized material placed in the field of view of a spectroscopic system allow calibration of the spectroscopic system. Response from the calibration spots is measured and used to calibrate for varying spectroscopic system operating parameters. The accurate calibration achieved allows quantitative spectroscopic analysis of responses taken at different times, different excitation conditions, and of different targets. 3 figs.

  11. Infrared laser spectroscopic trace gas sensing

    NASA Astrophysics Data System (ADS)

    Sigrist, Markus

    2016-04-01

    Chemical sensing and analyses of gas samples by laser spectroscopic methods are attractive owing to several advantages such as high sensitivity and specificity, large dynamic range, multi-component capability, and lack of pretreatment or preconcentration procedures. The preferred wavelength range comprises the fundamental molecular absorption range in the mid-infared between 3 and 15 μm, whereas the near-infrared range covers the (10-100 times weaker) higher harmonics and combination bands. The availability of near-infrared and, particularly, of broadly tunable mid-infrared sources like external cavity quantum cascade lasers (EC-QCLs), interband cascade lasers (ICLs), difference frequency generation (DFG), optical parametric oscillators (OPOs), recent developments of diode-pumped lead salt semiconductor lasers, of supercontinuum sources or of frequency combs have eased the implementation of laser-based sensing devices. Sensitive techniques for molecular absorption measurements include multipass absorption, various configurations of cavity-enhanced techniques such as cavity ringdown (CRD), or of photoacoustic spectroscopy (PAS) including quartz-enhanced (QEPAS) or cantilever-enhanced (CEPAS) techniques. The application requirements finally determine the optimum selection of laser source and detection scheme. In this tutorial talk I shall discuss the basic principles, present various experimental setups and illustrate the performance of selected systems for chemical sensing of selected key atmospheric species. Applications include an early example of continuous vehicle emission measurements with a mobile CO2-laser PAS system [1]. The fast analysis of C1-C4 alkanes at sub-ppm concentrations in gas mixtures is of great interest for the petrochemical industry and was recently achieved with a new type of mid-infrared diode-pumped piezoelectrically tuned lead salt vertical external cavity surface emitting laser (VECSEL) [2]. Another example concerns measurements on short

  12. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

    EPA Science Inventory

    The sorption and desorption of Pb on RuO2 xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity of nearest atomic neighbo...

  13. Arsenate Adsorption On Ruthenium Oxides: A Spectroscopic And Kinetic Investigation

    EPA Science Inventory

    Arsenate adsorption on amorphous (RuO2•1.1H2O) and crystalline (RuO2) ruthenium oxides was evaluated using spectroscopic and kinetic methods to elucidate the adsorption mechanism. Extended X-ray absorption fine structure spectroscopy (EXAFS) was ...

  14. Super-resolution spectroscopic microscopy via photon localization.

    PubMed

    Dong, Biqin; Almassalha, Luay; Urban, Ben E; Nguyen, The-Quyen; Khuon, Satya; Chew, Teng-Leong; Backman, Vadim; Sun, Cheng; Zhang, Hao F

    2016-01-01

    Traditional photon localization microscopy analyses only the spatial distributions of photons emitted by individual molecules to reconstruct super-resolution optical images. Unfortunately, however, the highly valuable spectroscopic information from these photons have been overlooked. Here we report a spectroscopic photon localization microscopy that is capable of capturing the inherent spectroscopic signatures of photons from individual stochastic radiation events. Spectroscopic photon localization microscopy achieved higher spatial resolution than traditional photon localization microscopy through spectral discrimination to identify the photons emitted from individual molecules. As a result, we resolved two fluorescent molecules, which were 15 nm apart, with the corresponding spatial resolution of 10 nm-a four-fold improvement over photon localization microscopy. Using spectroscopic photon localization microscopy, we further demonstrated simultaneous multi-colour super-resolution imaging of microtubules and mitochondria in COS-7 cells and showed that background autofluorescence can be identified through its distinct emission spectra. PMID:27452975

  15. Super-resolution spectroscopic microscopy via photon localization

    NASA Astrophysics Data System (ADS)

    Dong, Biqin; Almassalha, Luay; Urban, Ben E.; Nguyen, The-Quyen; Khuon, Satya; Chew, Teng-Leong; Backman, Vadim; Sun, Cheng; Zhang, Hao F.

    2016-07-01

    Traditional photon localization microscopy analyses only the spatial distributions of photons emitted by individual molecules to reconstruct super-resolution optical images. Unfortunately, however, the highly valuable spectroscopic information from these photons have been overlooked. Here we report a spectroscopic photon localization microscopy that is capable of capturing the inherent spectroscopic signatures of photons from individual stochastic radiation events. Spectroscopic photon localization microscopy achieved higher spatial resolution than traditional photon localization microscopy through spectral discrimination to identify the photons emitted from individual molecules. As a result, we resolved two fluorescent molecules, which were 15 nm apart, with the corresponding spatial resolution of 10 nm--a four-fold improvement over photon localization microscopy. Using spectroscopic photon localization microscopy, we further demonstrated simultaneous multi-colour super-resolution imaging of microtubules and mitochondria in COS-7 cells and showed that background autofluorescence can be identified through its distinct emission spectra.

  16. Super-resolution spectroscopic microscopy via photon localization

    PubMed Central

    Dong, Biqin; Almassalha, Luay; Urban, Ben E.; Nguyen, The-Quyen; Khuon, Satya; Chew, Teng-Leong; Backman, Vadim; Sun, Cheng; Zhang, Hao F.

    2016-01-01

    Traditional photon localization microscopy analyses only the spatial distributions of photons emitted by individual molecules to reconstruct super-resolution optical images. Unfortunately, however, the highly valuable spectroscopic information from these photons have been overlooked. Here we report a spectroscopic photon localization microscopy that is capable of capturing the inherent spectroscopic signatures of photons from individual stochastic radiation events. Spectroscopic photon localization microscopy achieved higher spatial resolution than traditional photon localization microscopy through spectral discrimination to identify the photons emitted from individual molecules. As a result, we resolved two fluorescent molecules, which were 15 nm apart, with the corresponding spatial resolution of 10 nm—a four-fold improvement over photon localization microscopy. Using spectroscopic photon localization microscopy, we further demonstrated simultaneous multi-colour super-resolution imaging of microtubules and mitochondria in COS-7 cells and showed that background autofluorescence can be identified through its distinct emission spectra. PMID:27452975

  17. Combined in situ FTIR-spectroscopic and electrochemical analysis of nanopores in ultra-thin SiOx-like plasma polymer barrier films

    NASA Astrophysics Data System (ADS)

    Liu, C.-N.; Ozkaya, B.; Steves, S.; Awakowicz, P.; Grundmeier, G.

    2013-02-01

    Plasma polymerized SiOx barrier films were investigated by means of in situ spectroscopic and electrochemical methods to correlate the process parameters such as applied substrate bias with the resulting barrier properties. SiOx layers with various hexamethyldisiloxane/oxygen ratio were deposited with and without applied substrate bias. The resulting film morphologies were characterized by means of atomic force microscopy, and the presence of nanopores was analysed by cyclic voltammetry. In order to compare the film density and the presence of nanopore structure, evaluation of interfacial hydroxyl groups was performed by means of discrete polarization modulation Fourier transform infrared reflection-absorption spectroscopy in atmospheres with controlled partial pressures of H2O or D2O. It could be shown that the electrochemical and in situ spectroscopic approach allows for the analysis of nanopores and that a clear correlation of process parameters and film structure can be established.

  18. MeCaSDa and ECaSDa: Methane and ethene calculated spectroscopic databases for the virtual atomic and molecular data centre

    NASA Astrophysics Data System (ADS)

    Ba, Yaye Awa; Wenger, Christian; Surleau, Romain; Boudon, Vincent; Rotger, Maud; Daumont, Ludovic; Bonhommeau, David A.; Tyuterev, Vladimir G.; Dubernet, Marie-Lise

    2013-11-01

    Two spectroscopic relational databases, denoted MeCaSDa and ECaSDa, have been implemented for methane and ethene, and included in VAMDC (Virtual Atomic and Molecular Data Centre, http://portal.vamdc.eu/vamdc_portal/home.seam). These databases collect calculated spectroscopic data from the accurate analyses previously performed for the electronic ground state of methane, ethene, and some of their isotopologues: 12CH4, 13CH4, and 12C2H4. Both infrared absorption and Raman scattering lines are included. The polyad structures are reported and the transitions are precisely described by their energy, their intensity and the full description of the lower and upper states involved in the transitions. The relational schemas of ECaSDa and MeCaSDa databases are equivalent and optimised to enable the better compromise between data retrieval and compatibility with the XSAMS (XML Schema for Atoms, Molecules, and Solids) format adopted within the VAMDC European project.

  19. Synthesis, characterization and spectroscopic investigation of a novel phenylhydrazone Schiff base with solvatochromism.

    PubMed

    Li, Mingtian; Huang, Jun; Zhou, Xuan; Luo, Hong

    2010-02-01

    A novel Schiff base of 4,5-diazafluorene-9-p-nitrophenylhydrazone (DAFND) has been synthesized and characterized. The crystal structures of DAFND and its analogue 4,5-diazafluorene-9-phenylhydrazone (DAFPD) were determined by single crystal X-ray diffraction method. X-ray analyses reveal that DAFPD comprise of a nonplanar molecule and all atoms of DAFND are essentially coplanar. The color of DAFND changes from brown to blue when heated, so called thermochromism and the spectroscopic properties of the two compounds are investigated by electronic absorption spectra, showing DAFND possess solvatochromism, while DAFPD does not have thermochromic and solvatochromic properties. The lambda(max) of DAFND within various pure solvents are different ranging from 370 nm in toluene to 614 nm in pyridine. The imaginable mechanisms of thermochromism and solvatochromism are proposed. PMID:20031480

  20. Synthesis, characterization and spectroscopic investigation of a novel phenylhydrazone Schiff base with solvatochromism

    NASA Astrophysics Data System (ADS)

    Li, Mingtian; Huang, Jun; Zhou, Xuan; Luo, Hong

    2010-02-01

    A novel Schiff base of 4,5-diazafluorene-9- p-nitrophenylhydrazone (DAFND) has been synthesized and characterized. The crystal structures of DAFND and its analogue 4,5-diazafluorene-9-phenylhydrazone (DAFPD) were determined by single crystal X-ray diffraction method. X-ray analyses reveal that DAFPD comprise of a nonplanar molecule and all atoms of DAFND are essentially coplanar. The color of DAFND changes from brown to blue when heated, so called thermochromism and the spectroscopic properties of the two compounds are investigated by electronic absorption spectra, showing DAFND possess solvatochromism, while DAFPD does not have thermochromic and solvatochromic properties. The λmax of DAFND within various pure solvents are different ranging from 370 nm in toluene to 614 nm in pyridine. The imaginable mechanisms of thermochromism and solvatochromism are proposed.

  1. Spectroscopic infrared ellipsometry

    NASA Astrophysics Data System (ADS)

    Roseler, A.

    1992-03-01

    The spectroscopic infrared ellipsometry (SIRE) by means of the combination of a photometric ellipsometer with a Fourier transform spectrometer is used to measure optical properties in the infrared. From the observed four Stokes parameters, the spectrum of the degree of polarization after the reflection at the sample is calculated and discussed.

  2. Spectroscopic wear detector

    NASA Technical Reports Server (NTRS)

    Madzsar, George C. (Inventor)

    1993-01-01

    The elemental composition of a material exposed to hot gases and subjected to wear is determined. Atoms of an elemental species not appearing in this material are implanted in a surface at a depth based on the maximum allowable wear. The exhaust gases are spectroscopically monitored to determine the exposure of these atoms when the maximum allowable wear is reached.

  3. Laser spectroscopic measurement of helium isotope ratios.

    SciTech Connect

    Wang, L.-B.; Mueller, P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Sano, Y.; Sturchio, N.; Univ. of Illinois; Univ. of Tokyo; Univ. of Illinois at Chicago

    2003-06-13

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of {sup 3}He/{sup 4}He = 10{sup -7}--10{sup -5}. The resonant absorption of 1083 nm laser light by the metastable {sup 3}He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of {sup 4}He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3{sigma} detection limit of {sup 3}He in helium is 4 x 10{sup -9}. This demonstration required a 200 {mu}L STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  4. Fourier transform infrared spectroscopic study of truffles

    NASA Astrophysics Data System (ADS)

    Zhao, Dezhang; Liu, Gang; Song, Dingshan; Liu, Jian-hong; Zhou, Yilan; Ou, Jiaming; Sun, Shizhong

    2006-01-01

    Truffles are rare wild growing edible mushrooms belonging to Ascomycetes. In this paper, Fourier transform infrared (FTIR) spectroscopy was used to obtain vibrational spectra of truffles. The results show that the mushrooms exhibit characteristic spectra. The two strongest absorption bands appear at about 1077cm -1 and 1040 cm -1, which were described as C-O stretching in carbohydrate. The vibrational spectra indicate that the main compositions of the truffles are polysaccharide and protein. According to the characteristics bands and absorption ratios of spectra, different species of truffles can be discriminated. It is also found the great changes between moldy and healthy truffles, which the major differences are observed in the bands of protein. In addition, FTIR spectral differences are observed between the same species of truffles from different producing areas. It is showed that the FTIR spectroscopic method is valuable tool for rapid and nondestructive analysis of truffles prior to any extraction method used.

  5. Les possibilités et limitations de l'atomisation électrothermique en spectrométrie d'absorption atomique lors de l'analyse directe des metaux lourds dans l'eau de mer

    NASA Astrophysics Data System (ADS)

    Hoenig, M.; Wollast, R.

    This work shows the analytical possibilities of an electrothermal atomizer for the direct determination of trace metals in sea-water. The high background signals generated by the matrix perturb in particular volatile elements because of the low decomposition temperature allowed. In the case of cadmium, addition of ascorbic acid to the sample permits the modification of the atomization mechanism and the reduction of the optimum temperature. Under these conditions, absorption peak of the cadmium precedes the background absorption and consequently the analysis is no longer limited by the magnitude of the matrix signal: the determination of cadmium concentrations far below the μg -1 level is easily possible. Although the direct determination of the other elements should be in principle less disturbed by the background, the analytical performance is poorer than for cadmium. Limits of determination of the order from 0.1 to 1 μg -1 can be reached for chromium, copper and manganese. Lead and nickel appeared to be the most difficult elements; their direct determination is only possible in polluted coastal or estuarine waters. The injection of the sample as an aerosol into hot graphite tube showed to be well adapted to this kind of investigations. The simultaneous visualization of specific and background signals allows interpretations which until now were impossible with commercially available apparatus.

  6. Spectroscopic analyses of pollutants in water, sediment and fish

    NASA Astrophysics Data System (ADS)

    Abdel-Gawad, Fagr Kh.; Ibrahim, Hanan S.; Ammar, Nabila S.; Ibrahim, Medhat

    2012-11-01

    Water ways in Egypt is suffering from continual discharge without adequate treatment especially in the Delta and greater Cairo area. Accordingly water, sediments and catfishes were collected from El Mouheet El Youmna drain in Giza. Cd, Cr, Pb and Zn were determined furthermore the molecular structure of sediment and catfish were conducted with FTIR spectroscopy. Although studied metals were lower in water, higher values are recorded in sediment and catfish samples. FTIR shows possible interaction among metals and organic structures mainly proteins. The bioaccumulation of Pb and Cd proportion was significantly increased in the liver tissues of catfish. A correlation coefficient among sediment and fish liver metals accumulation exist. This infers that the waste assimilation capacity for the drain is high, a phenomena that could be ascribed to dilution, sedimentation and continual water exchange. Furthermore, the genotoxicity affect in catfish genomic corroborates the genus diagnostic markers which attributed to long pollution. This is an indication that agriculture and industrial wastes discharged into the drain has badly a significant effect on the ecological balance.

  7. Interactions of thioflavin T with serum albumins: Spectroscopic analyses

    NASA Astrophysics Data System (ADS)

    Sen, Priyankar; Fatima, Sadaf; Ahmad, Basir; Khan, Rizwan Hasan

    2009-09-01

    The interaction of thioflavin T (ThT) with serum albumins from four different mammalian species i.e. human, bovine, porcine and rabbit, has been investigated by circular dichroism (CD), fluorescence spectroscopy and ITC. The binding constant ( K) for HSA was found to be 9.9 × 10 4 M -1, 4.3 × 10 4 M -1 for RSA, 1.07 × 10 4 M -1 for PSA and 0.3 × 10 4 M -1 for BSA and the number of binding sites ( n) were 1.14, 1.06, 0.94 and 0.8, respectively, which is very significant. By using unfolding pathway of HSA in the presence of urea, domain II of HSA has been assigned to possess binding site of ThT. Its binding constant is comparable to many drugs that bind at domain II of HSA, like salicylate, warfarin, digitoxin, etc. Acting force between HSA and ThT is showing that both hydrophobic and electrostatic forces have contributed for the interaction. Δ Gbinding, Δ H and Δ S were calculated to be -28.46 kJ mol -1, -3.50 kJ mol -1 and 81.04 J K -1 mol -1, respectively. The data described here will help to increase our understanding about the interaction of ThT with native proteins. The results also indicate that care must be taken while using ThT as a probe for detecting amyloid fibrils.

  8. Spectroscopic analyses of soil samples outside Nile Delta of Egypt.

    PubMed

    Fakhry, Ahmed; Osman, Osama; Ezzat, Hend; Ibrahim, Medhat

    2016-11-01

    Soil in Egypt, especially around Delta is exposed to various pollutants which are affecting adversely soil fertility and stability. Humic Acids (HA) as a main part of soil organic matter (SOM) represent the heart of the interaction process of inorganic pollutants with soil. Consequently, Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonances (NMR) were used to characterize soil, sediment and extracted HA. Resulting data confirmed that the HA was responsible for transporting inorganic pollutants from surface to subsurface reaching the ground water, which may represent a high risk on public health. The transport process is coming as carboxyl in surface soil changed into metal carboxylate then transferred into the carboxyl in bottom soil. PMID:27294554

  9. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  10. Spectroscopically Accurate Line Lists for Application in Sulphur Chemistry

    NASA Astrophysics Data System (ADS)

    Underwood, D. S.; Azzam, A. A. A.; Yurchenko, S. N.; Tennyson, J.

    2013-09-01

    Monitoring sulphur chemistry is thought to be of great importance for exoplanets. Doing this requires detailed knowledge of the spectroscopic properties of sulphur containing molecules such as hydrogen sulphide (H2S) [1], sulphur dioxide (SO2), and sulphur trioxide (SO3). Each of these molecules can be found in terrestrial environments, produced in volcano emissions on Earth, and analysis of their spectroscopic data can prove useful to the characterisation of exoplanets, as well as the study of planets in our own solar system, with both having a possible presence on Venus. A complete, high temperature list of line positions and intensities for H32 2 S is presented. The DVR3D program suite is used to calculate the bound ro-vibration energy levels, wavefunctions, and dipole transition intensities using Radau coordinates. The calculations are based on a newly determined, spectroscopically refined potential energy surface (PES) and a new, high accuracy, ab initio dipole moment surface (DMS). Tests show that the PES enables us to calculate the line positions accurately and the DMS gives satisfactory results for line intensities. Comparisons with experiment as well as with previous theoretical spectra will be presented. The results of this study will form an important addition to the databases which are considered as sources of information for space applications; especially, in analysing the spectra of extrasolar planets, and remote sensing studies for Venus and Earth, as well as laboratory investigations and pollution studies. An ab initio line list for SO3 was previously computed using the variational nuclear motion program TROVE [2], and was suitable for modelling room temperature SO3 spectra. The calculations considered transitions in the region of 0-4000 cm-1 with rotational states up to J = 85, and includes 174,674,257 transitions. A list of 10,878 experimental transitions had relative intensities placed on an absolute scale, and were provided in a form suitable

  11. Methane overtone absorption by intracavity laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Obrien, James J.

    1990-01-01

    Interpretation of planetary methane (CH4) visible-near IR spectra, used to develop models of planetary atmospheres, has been hampered by a lack of suitable laboratory spectroscopic data. The particular CH4 spectral bands are due to intrinsically weak, high overtone-combination transitions too complex for classical spectroscopic analysis. The traditional multipass cell approach to measuring spectra of weakly absorbing species is insufficiently sensitive to yield reliable results for some of the weakest CH4 absorption features and is difficult to apply at the temperatures of the planetary environments. A time modulated form of intracavity laser spectroscopy (ILS), has been shown to provide effective absorption pathlengths of 100 to 200 km with sample cells less than 1 m long. The optical physics governing this technique and the experimental parameters important for obtaining reliable, quantitative results are now well understood. Quantitative data for CH4 absorption obtained by ILS have been reported recently. Illustrative ILS data for CH4 absorption in the 619.7 nm and 681.9 nm bands are presented. New ILS facilities at UM-St. Louis will be used to measure CH4 absorption in the 700 to 1000 nm region under conditions appropriate to the planetary atmospheres.

  12. Sociopolitical Analyses.

    ERIC Educational Resources Information Center

    Van Galen, Jane, Ed.; And Others

    1992-01-01

    This theme issue of the serial "Educational Foundations" contains four articles devoted to the topic of "Sociopolitical Analyses." In "An Interview with Peter L. McLaren," Mary Leach presented the views of Peter L. McLaren on topics of local and national discourses, values, and the politics of difference. Landon E. Beyer's "Educational Studies and…

  13. New Developments of Broadband Cavity Enhanced Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  14. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  15. Spectroscopically Unlocking Exoplanet Characteristics

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole

    2016-05-01

    Spectroscopy plays a critical role in a number of areas of exoplanet research. The first exoplanets were detected by precisely measuring Doppler shifts in high resolution (R ~ 100,000) stellar spectra, a technique that has become known as the Radial Velocity (RV) method. The RV method provides critical constraints on exoplanet masses, but is currently limited to some degree by robust line shape predictions. Beyond the RV method, spectroscopy plays a critical role in the characterization of exoplanets beyond their mass and radius. The Hubble Space Telescope has spectroscopically observed the atmospheres of exoplanets that transit their host stars as seen from Earth giving us key insights into atmospheric abundances of key atomic and molecular species as well as cloud optical properties. Similar spectroscopic characterization of exoplanet atmospheres will be carried out at higher resolution (R ~ 100-3000) and with broader wavelength coverage with the James Webb Space Telescope. Future missions such as WFIRST that seek to the pave the way toward the detection and characterization of potentially habitable planets will have the capability of directly measuring the spectra of exoplanet atmospheres and potentially surfaces. Our ability to plan for and interpret spectra from exoplanets relies heavily on the fidelity of the spectroscopic databases available and would greatly benefit from further laboratory and theoretical work aimed at optical properties of atomic, molecular, and cloud/haze species in the pressure and temperature regimes relevant to exoplanet atmospheres.

  16. Line shape studies in CW dye laser intracavity absorption

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Brink, G. O.; Spence, S.; Lakkaraju, H. S.

    1980-01-01

    The line shape of the signals observed by intracavity absorption in an atomic beam of barium is studied as a function of absorber density. Complex structure is observed consisting of both absorption and enhancement features. Comparison is made with models of intracavity absorption, and it is concluded that the rate equation model in its present form does not explain the structure. On the other hand the super-regen model does seem able to partially account for the observed structure. The complexity of the line shape will directly affect those workers who are using intracavity absorption as a spectroscopic technique.

  17. Structure analyses using X-ray photoelectron spectroscopy and X-ray absorption near edge structure for amorphous MS3 (M: Ti, Mo) electrodes in all-solid-state lithium batteries

    NASA Astrophysics Data System (ADS)

    Matsuyama, Takuya; Deguchi, Minako; Mitsuhara, Kei; Ohta, Toshiaki; Mori, Takuya; Orikasa, Yuki; Uchimoto, Yoshiharu; Kowada, Yoshiyuki; Hayashi, Akitoshi; Tatsumisago, Masahiro

    2016-05-01

    Electronic structure changes of sulfurs in amorphous TiS3 and MoS3 for positive electrodes of all-solid-state lithium batteries are examined by X-ray photoelectron spectroscopy (XPS) and the X-ray absorption near edge structure (XANES). The all-solid-state cell with amorphous TiS3 electrode shows the reversible capacity of about 510 mAh g-1 for 10 cycles with sulfur-redox in amorphous TiS3 during charge-discharge process. On the other hand, the cell with amorphous MoS3 shows the 1st reversible capacity of about 720 mAh g-1. The obtained capacity is based on the redox of both sulfur and molybdenum in amorphous MoS3. The irreversible capacity of about 50 mAh g-1 is observed at the 1st cycle, which is attributed to the irreversible electronic structure change of sulfur during the 1st cycle. The electronic structure of sulfur in amorphous MoS3 after the 10th charge is similar to that after the 1st charge. Therefore, the all-solid-state cell with amorphous MoS3 electrode shows relatively good cyclability after the 1st cycle.

  18. Spectroscopic survey of LAMOST

    NASA Astrophysics Data System (ADS)

    Zhao, Yongheng

    2014-07-01

    LAMOST is a special reflecting Schmidt telescope. LAMOST breaks through the bottleneck of the large scale spectroscopic survey observation with both large aperture (effective aperture of 3.6 - 4.9m) and wide field of view (5 degrees). It is an innovative active reflecting Schmidt configuration achieved by changing mirror surface continuously to achieve a series different reflecting Schmidt system in different moments. By using the parallel controllable fiber positioning technique, the focal surface of 1.75 meters in diameter accommodates 4000 optical fibers. Also, LAMOST has 16 spectrographs with 32 CCD cameras. LAMOST is the telescope of the highest spectrum acquiring rate. As a national large scientific project, LAMOST project was proposed formally in 1996. The construction was started in 2001 and completed in 2008. After commission period, LAMOST pilot survey was started in October 2011 and spectroscopic survey began in September 2012. From October 2011 to June 2013, LAMOST has obtained more than 2 million spectra of celestial objects. There are 1.7 million spectra of stars, in which the stellar parameters (effective temperature, surface gravity, metalicitiy and radial velocity) of more than 1 million stars was obtained. In the first period of spectroscopic survey of LAMOST, 5 million of stellar spectra will be obtained and will make substantial contribution to the study of the stellar astrophysics and the structure of the Galaxy, such as the spheroid substructure of the Galaxy, the galactic gravitational potential and the distribution of the dark matter in the Galaxy, the extremely metal poor stars and hypervelocity stars, the 3D extinction in the Galaxy, the structure of thin and thick disks of the Galaxy, and so on.

  19. Spectroscopic investigations of heme proteins

    NASA Astrophysics Data System (ADS)

    Ogilvie, Jennifer Pauline

    Using several novel spectroscopic techniques, we investigate the dynamics of heme proteins over the full range of time scales relevant to their function. With ˜10 femtosecond time resolution we use ultrafast pump-probe spectroscopy to gain insight into the earliest dynamics initiated by the photodissociation of the carbon monoxide ligand from myoglobin. Coherent oscillations that are driven by the bond-breaking event reveal several vibrational modes of the heme that provide the driving force for the initial motions along the pathway to protein function. Much later along this pathway we address the question of ligand escape from myoglobin. With this purpose we develop heterodyne-detected diffractive-optics-based phase-grating spectroscopy, which provides more than 2 orders of magnitude increase in sensitivity for the measurement of volume changes and energetics. The improved sensitivity allows us to directly observe the ligand escape, which occurs via a number of discrete routes through the protein. Following the escape process, we observe the full cycle of dynamics that is complete when the carbon monoxide ligand rebinds to the protein. Using a resonant probe we re-examine the dynamics of ligand escape from myoglobin using transient absorption and transient-grating spectroscopy. This study confirms the findings of the previous off-resonant work, and allows us to explore the relationship between the observables in the phase-grating experiment and other resonant spectroscopies. The various dynamical processes of myoglobin provide a basis for understanding the structure/function relationship at the single protein level. This lays the foundation for a description of protein-protein interactions such as cooperativity in hemoglobin.

  20. Visible Spectroscopic Observation Of Asteroid 162173 (1999ju3) With The Gemini-s Telescope

    NASA Astrophysics Data System (ADS)

    Sugita, Seiji; Kuroda, D.; Kameda, S.; Hasegawa, S.; Kamata, S.; Abe, M.; Ishiguro, M.; Takato, N.; Yoshikawa, M.

    2012-10-01

    Asteroid 162173 (1999JU3; hereafter JU3) is the target of the Hayabusa-2 mission. Its visible reflectance spectra have been observed a few times [1,2], and obtained spectra exhibit a wide variety of spectral patterns ranging from a spectra with absorption in the UV region (May 1999) to a flat spectrum with a faint broad absorption centered around 0.6 microns (September 2007) and that with UV absorption and strong broad absorption centered around 0.7 micron (July 2007). The apparent large spectral variation may be due to variegation on the asteroid surface. Such variegation would make a large influence on remote sensing strategy for Hayabusa-2 before its sampling operations. In order to better constraint the spectral properties of JU3, we conducted visible spectroscopic observations at the GEMINI-South observatory 8.1-m telescope with the GMOS instrument. We could obtain three different sets of data in June and July 2012. Although the JU3 rotation phases of two of the observation are close to each other, the other is about 120 degrees away from the two. Our preliminary analyses indicate that these three spectra are slightly reddish but generally flat across the observed wavelength range (0.47 - 0.89 microns). The observed flat spectra are most similar to the spectrum obtained in September 2007, which probably has the highest signal-to-noise ratio among the previous three spectra. This result suggests that material with a flat spectrum probably covers a dominant proportion of the JU3 surface and that the other two types of previously obtained spectra may not cover a very large fraction of the JU3 surface. [1] Binzel, R. P. et al. (2001) Icarus, 151, 139-149; [2] Vilas, F. (2008) AJ, 135, 1101-1105.

  1. Spectroscopic observations of spatial and temporal variations on Venus

    NASA Technical Reports Server (NTRS)

    Young, A. T.; Young, L. G.; Woszczyk, A.

    1974-01-01

    Details of the Table Mountain spectroscopic patrol of Venus in September-October 1972 are given. The data indicate systematic variation over the disc, with more CO2 absorption near the terminator than at the limb, and slightly more in the southern than in the northern hemisphere. The semiregular four-day variation, reported to occur simultaneously over the disk at 8689 A by Young et al. (1973), is confirmed by observations of the 7820 A and 7883 A CO2 bands.

  2. New infrared spectroscopic database for bromine nitrate

    NASA Astrophysics Data System (ADS)

    Wagner, Georg; Birk, Manfred

    2016-08-01

    Fourier transform infrared measurements of bromine nitrate have been performed in the spectral region 675-1400 cm-1 at 0.014 cm-1 spectral resolution. Absorption cross sections were derived from 38 spectra covering the temperature range from 203 to 296 K and air pressure range from 0 to 190 mbar. For line-by-line analysis, further spectra were recorded at 0.00094 cm-1 spectral resolution at 223 and 293 K. The sample was synthesized from ClONO2 and Br2. Band strengths of the bands ν3 around 803 cm-1 and ν2 around 1286 cm-1 were determined from three pure BrONO2 measurements at different temperatures and pressures. Number densities in the absorption cell were derived from pressure measurements of the purified sample taking into account small amounts of impurities determined spectroscopically. Resulting band strengths are Sν3 = 2.872(52) × 10-17 cm2 molec-1 cm-1 and Sν2 = 3.63(15) × 10-17 cm2 molec-1 cm-1. Absorption cross sections of all measurements were scaled to these band strengths. Further data reduction was achieved with an interpolation scheme based on two-dimensional polynomials in ln(pressure) and temperature. The database is well-suited for remote-sensing application and should reduce the atmospheric bromine nitrate error budget substantially.

  3. Spectroscopic survey of LAMOST

    NASA Astrophysics Data System (ADS)

    Zhao, Yongheng

    2015-08-01

    LAMOST is a special reflecting Schmidt telescope. LAMOST breaks through the bottleneck of the large scale spectroscopic survey observation with both large aperture (effective aperture of 3.6 - 4.9m) and wide field of view (5 degrees). It is an innovative active reflecting Schmidt configuration achieved by changing mirror surface continuously to achieve a series different reflecting Schmidt system in different moments. By using the parallel controllable fiber positioning technique, the focal surface of 1.75 meters in diameter accommodates 4000 optical fibers. Also, LAMOST has 16 spectrographs with 32 CCD cameras. LAMOST is the telescope of the highest spectrum acquiring rate.In the spectroscopic survey of LAMOST from October 2011 to June 2014, LAMOST has obtained more than 4.13 million spectra of celestial objects. There are 3.27 million spectra of stars, in which the stellar parameters of 2.16 million stars were obtained.In the five-year regular survey upto 2017, LAMOST will obtaine 5 million stellar spectra, which would make substantial contribution to the study of the stellar astrophysics and the structure of the Galaxy, such as the spheroid substructure of the Galaxy, the galactic gravitational potential and the distribution of the dark matter in the Galaxy, the extremely metal poor stars and hypervelocity stars, the 3D extinction in the Galaxy, the structure of thin and thick disks of the Galaxy, and so on.

  4. Absorption heat pumps

    NASA Astrophysics Data System (ADS)

    Huhtinen, M.; Heikkilae, M.; Andersson, R.

    1987-03-01

    The aim of the study was to analyze the technical and economic feasibility of absorption heat pumps in Finland. The work was done as a case study: the technical and economic analyses have been carried out for six different cases, where in each the suitable size and type of the heat pump plant and the auxiliary components and connections were specified. The study also detailed the costs concerning the procurement, installation and test runs of the machinery, as well as the savings in energy costs incurred by the introduction of the plant. Conclusions were drawn of the economic viability of the applications studied. The following cases were analyzed: heat recovery from flue gases and productin of district heat in plants using peat, natural gas, and municipal wastes as a fuel. Heat recovery in the pulp and paper industry for the upgrading of pressure of secondary steam and for the heating of white liquor and combustion and drying the air. Heat recovery in a peat-fulled heat and power plant from flue gases that have been used for the drying of peat. According to the study, the absorption heat pump suits best to the production of district heat, when the heat source is the primary energy is steam produced by the boiler. Included in the flue as condensing is the purification of flue gases. Accordingly, benefit is gained on two levels in thick applications. In heat and power plants the use of absorption heat pumps is less economical, due to the fact that the steam used by the pump reduces the production of electricity, which is rated clearly higher than heat.

  5. The GEISA Spectroscopic Database System in its latest Edition

    NASA Astrophysics Data System (ADS)

    Jacquinet-Husson, N.; Crépeau, L.; Capelle, V.; Scott, N. A.; Armante, R.; Chédin, A.

    2009-04-01

    GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Spectroscopic Information)[1] is a computer-accessible spectroscopic database system, designed to facilitate accurate forward planetary radiative transfer calculations using a line-by-line and layer-by-layer approach. It was initiated in 1976. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI (Infrared Atmospheric Sounding Interferometer on board the METOP European satellite -http://earth-sciences.cnes.fr/IASI/)) through the GEISA/IASI database[2] derived from GEISA. Since the Metop (http://www.eumetsat.int) launch (October 19th 2006), GEISA/IASI is the reference spectroscopic database for the validation of the level-1 IASI data, using the 4A radiative transfer model[3] (4A/LMD http://ara.lmd.polytechnique.fr; 4A/OP co-developed by LMD and Noveltis with the support of CNES). Also, GEISA is involved in planetary research, i.e.: modelling of Titan's atmosphere, in the comparison with observations performed by Voyager: http://voyager.jpl.nasa.gov/, or by ground-based telescopes, and by the instruments on board the Cassini-Huygens mission: http://www.esa.int/SPECIALS/Cassini-Huygens/index.html. The updated 2008 edition of GEISA (GEISA-08), a system comprising three independent sub-databases devoted, respectively, to line transition parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols, will be described. Spectroscopic parameters quality requirement will be discussed in the context of comparisons between observed or simulated Earth's and other planetary atmosphere spectra. GEISA is implemented on the CNES/CNRS Ether Products and Services Centre WEB site (http://ether.ipsl.jussieu.fr), where all archived spectroscopic data can be handled through general and user friendly associated management software facilities. More than 350 researchers are

  6. Search for planets by spectroscopic methods

    NASA Technical Reports Server (NTRS)

    Serkowski, K.

    1980-01-01

    Spectroscopic means of detecting the motion of a star around a star-planet barycenter are considered. The precision of such an observation, which requires a radial velocity error of not more than 5 m/sec, is discussed in relation to the spectral resolutions of the detectors utilized. The University of Arizona radial velocity spectrometer is then presented, with particular attention given to the location of the absorption cell in a beam of light from an incandescent bulb, high-accuracy wavelength calibration involving the use of a Fabry-Perot interferometer in front of an echelle spectrograph, and future plans for the use of light reflected from a Fabry-Perot etalon to improve transmittance. On the basis of these techniques, it is expected that radial velocities with accuracies sufficient for the detection of extrasolar planets will be obtained.

  7. Spectroscopic Ellipsometry Applications in Advanced Lithography Research

    NASA Astrophysics Data System (ADS)

    Synowicki, R. A.; Pribil, Greg K.; Hilfiker, James N.; Edwards, Kevin

    2005-09-01

    Spectroscopic ellipsometry (SE) is an optical metrology technique widely used in the semiconductor industry. For lithography applications SE is routinely used for measurement of film thickness and refractive index of polymer photoresist and antireflective coatings. While this remains a primary use of SE, applications are now expanding into other areas of advanced lithography research. New applications include immersion lithography, phase-shift photomasks, transparent pellicles, 193 and 157 nm lithography, stepper optical coatings, imprint lithography, and even real-time monitoring of etch development rate in liquid ambients. Of recent interest are studies of immersion fluids where knowledge of the fluid refractive index and absorption are critical to their use in immersion lithography. Phase-shift photomasks are also of interest as the thickness and index of the phase-shift and absorber layers must be critically controlled for accurate intensity and phase transmission. Thin transparent pellicles to protect these masks must be also characterized for thickness and refractive index. Infrared ellipsometry is sensitive to chemical composition, film thickness, and how film chemistry changes with processing. Real-time monitoring of polymer film thickness during etching in a liquid developer allows etch rate and endpoint determination with monolayer sensitivity. This work considers these emerging applications to survey the current status of spectroscopic ellipsometry as a characterization technique in advanced lithography applications.

  8. Spectroscopic characterization of the Stentor photoreceptor.

    PubMed

    Walker, E B; Lee, T Y; Song, P S

    1979-09-20

    1. On the basis of chromatographic and spectroscopic (absorption, fluorescence and its polarization, fluorescence lifetime, circular dichroism) characterization of the Stentor photoreceptor (stentorin) for photophobic response, the photoreceptor chromophore released from mild acid hydrolysis has been identified as hypericin. 2. The native chromophore is apparently linked to a protein (65 K) containing Lys and several hydrophobic residues, which is soluble in acetone and n-pentane. The peptide-linked stentorin (I) chromophore exhibits circular dichroism in the visible region due to the induced optical activity provided by the peptide. 3. The sodium dodecyl sulfate polyacrylamide gel electrophoresis of a 38% fraction of the sucrose density centrifugation has resolved stentorin II proteins having molecular weights of 13 000, 16 000, 65 000 and 130 000. These proteins, as well as the acetone-soluble peptide, have been spectroscopically characterized with particular emphasis on their primary photoreactivity as the photophobic receptor of Stentor coeruleus. 4. Irradiation of whole living Stentor in dilute buffer solutions induces a decrease in the pH of the medium. A strong dependence upon pH in the fluorescence spectra of both synthetic and native chromophores is also evident, showing a significant drop in the pKa of one or more hydroxyl groups in the excited state. A mechanism for the photophobic response, based on this lowering of the pKa as the primary photoprocess, has been discussed. PMID:39631

  9. Survey for z>3 damped Ly alpha absorption systems: the evolution of neutral gas

    NASA Technical Reports Server (NTRS)

    Storrie-Lombardi, L. J.; Wolfe, A. M.

    2000-01-01

    We have completed spectroscopic observations using LRIS on the Keck 1 telescope of 30 very high redshift quasars, 11 selected for the presence of damped Ly alpha absorption systems and 19 with redshifts z>3.5 not previously surveyed for absorption systems.

  10. The role of tryptophans in the UV-B absorption of a UVR8 photoreceptor--a computational study.

    PubMed

    Wu, Qi; Huang, Bolong; Niehaus, T A; Yang, Xiaojing; Fan, Jun; Zhang, Rui-Qin

    2015-04-28

    Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) has been identified as a photoreceptor for ultraviolet-B (UV-B). Tryptophan (Trp) residues have been shown to play a critical role in the response to UV-B irradiation in UVR8. In this work, we explore the spectroscopic behaviors of Trps in different protein environments of the UVR8 structure using the time-dependent density functional tight-binding (TD-DFTB) scheme. We show that W233 exhibits the longest absorption wavelength, highlighting its potential as a terminal Trp chromophore in the UV-B harvesting antenna. Our electronic and optical property analyses using various amino acid models support the important roles of W285 and W233 in sensing UV-B light at longer absorption wavelengths (∼290 nm). We also provide evidence for the specific function of W94 in absorption at the longest wavelengths (305.8 nm in cluster II and 304.5 nm in cluster III). To these findings, we also add information about the influence of the arginine and aspartic acid residues surrounding the Trp pyramid on the particular absorption bands (280-300 nm) that are characteristic of the UV-B photoreceptor. PMID:25811850

  11. Infrared Spectroscopic Imaging: The Next Generation

    PubMed Central

    Bhargava, Rohit

    2013-01-01

    Infrared (IR) spectroscopic imaging seemingly matured as a technology in the mid-2000s, with commercially successful instrumentation and reports in numerous applications. Recent developments, however, have transformed our understanding of the recorded data, provided capability for new instrumentation, and greatly enhanced the ability to extract more useful information in less time. These developments are summarized here in three broad areas— data recording, interpretation of recorded data, and information extraction—and their critical review is employed to project emerging trends. Overall, the convergence of selected components from hardware, theory, algorithms, and applications is one trend. Instead of similar, general-purpose instrumentation, another trend is likely to be diverse and application-targeted designs of instrumentation driven by emerging component technologies. The recent renaissance in both fundamental science and instrumentation will likely spur investigations at the confluence of conventional spectroscopic analyses and optical physics for improved data interpretation. While chemometrics has dominated data processing, a trend will likely lie in the development of signal processing algorithms to optimally extract spectral and spatial information prior to conventional chemometric analyses. Finally, the sum of these recent advances is likely to provide unprecedented capability in measurement and scientific insight, which will present new opportunities for the applied spectroscopist. PMID:23031693

  12. Applications of absorption spectroscopy using quantum cascade lasers.

    PubMed

    Zhang, Lizhu; Tian, Guang; Li, Jingsong; Yu, Benli

    2014-01-01

    Infrared laser absorption spectroscopy (LAS) is a promising modern technique for sensing trace gases with high sensitivity, selectivity, and high time resolution. Mid-infrared quantum cascade lasers, operating in a pulsed or continuous wave mode, have potential as spectroscopic sources because of their narrow linewidths, single mode operation, tunability, high output power, reliability, low power consumption, and compactness. This paper reviews some important developments in modern laser absorption spectroscopy based on the use of quantum cascade laser (QCL) sources. Among the various laser spectroscopic methods, this review is focused on selected absorption spectroscopy applications of QCLs, with particular emphasis on molecular spectroscopy, industrial process control, combustion diagnostics, and medical breath analysis. PMID:25239063

  13. Quantum Entanglement Molecular Absorption Spectrum Simulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet; Kojima, Jun

    2006-01-01

    Quantum Entanglement Molecular Absorption Spectrum Simulator (QE-MASS) is a computer program for simulating two photon molecular-absorption spectroscopy using quantum-entangled photons. More specifically, QE-MASS simulates the molecular absorption of two quantum-entangled photons generated by the spontaneous parametric down-conversion (SPDC) of a fixed-frequency photon from a laser. The two-photon absorption process is modeled via a combination of rovibrational and electronic single-photon transitions, using a wave-function formalism. A two-photon absorption cross section as a function of the entanglement delay time between the two photons is computed, then subjected to a fast Fourier transform to produce an energy spectrum. The program then detects peaks in the Fourier spectrum and displays the energy levels of very short-lived intermediate quantum states (or virtual states) of the molecule. Such virtual states were only previously accessible using ultra-fast (femtosecond) laser systems. However, with the use of a single-frequency continuous wave laser to produce SPDC photons, and QEMASS program, these short-lived molecular states can now be studied using much simpler laser systems. QE-MASS can also show the dependence of the Fourier spectrum on the tuning range of the entanglement time of any externally introduced optical-path delay time. QE-MASS can be extended to any molecule for which an appropriate spectroscopic database is available. It is a means of performing an a priori parametric analysis of entangled photon spectroscopy for development and implementation of emerging quantum-spectroscopic sensing techniques. QE-MASS is currently implemented using the Mathcad software package.

  14. Enhanced squeezing by absorption

    NASA Astrophysics Data System (ADS)

    Grünwald, P.; Vogel, W.

    2016-04-01

    Absorption is usually expected to be detrimental to quantum coherence effects. However, there have been few studies into the situation for complex absorption spectra. We consider the resonance fluorescence of excitons in a semiconductor quantum well. The creation of excitons requires absorption of the incoming pump-laser light. Thus, the absorption spectrum of the medium acts as a spectral filter for the emitted light. Surprisingly, absorption can even improve quantum effects, as is demonstrated for the squeezing of the resonance fluorescence of the quantum-well system. This effect can be explained by an improved phase matching due to absorption.

  15. Spectroscopic classification of supernova candidates

    NASA Astrophysics Data System (ADS)

    Hodgkin, S. T.; Hall, A.; Fraser, M.; Campbell, H.; Wyrzykowski, L.; Kostrzewa-Rutkowska, Z.; Pietro, N.

    2014-09-01

    We report the spectroscopic classification of four supernovae at the 2.5m Isaac Newton Telescope on La Palma, using the Intermediate Dispersion Spectrograph and the R300V grating (3500-8000 Ang; ~6 Ang resolution).

  16. Spectroscopic optical coherence elastography

    PubMed Central

    Adie, Steven G.; Liang, Xing; Kennedy, Brendan F.; John, Renu; Sampson, David D.; Boppart, Stephen A.

    2010-01-01

    We present an optical technique to image the frequency-dependent complex mechanical response of a viscoelastic sample. Three-dimensional hyperspectral data, comprising two-dimensional B-mode images and a third dimension corresponding to vibration frequency, were acquired from samples undergoing external mechanical excitation in the audio-frequency range. We describe the optical coherence tomography (OCT) signal when vibration is applied to a sample and detail the processing and acquisition techniques used to extract the local complex mechanical response from three-dimensional data that, due to a wide range of vibration frequencies, possess a wide range of sample velocities. We demonstrate frequency-dependent contrast of the displacement amplitude and phase of a silicone phantom containing inclusions of higher stiffness. Measurements of an ex vivo tumor margin demonstrate distinct spectra between adipose and tumor regions, and images of displacement amplitude and phase demonstrated spatially-resolved contrast. Contrast was also observed in displacement amplitude and phase images of a rat muscle sample. These results represent the first demonstration of mechanical spectroscopy based on B-mode OCT imaging. Spectroscopic optical coherence elastography (S-OCE) provides a high-resolution imaging capability for the detection of tissue pathologies that are characterized by a frequency-dependent viscoelastic response. PMID:21164898

  17. Spectroscopic optical coherence elastography.

    PubMed

    Adie, Steven G; Liang, Xing; Kennedy, Brendan F; John, Renu; Sampson, David D; Boppart, Stephen A

    2010-12-01

    We present an optical technique to image the frequency-dependent complex mechanical response of a viscoelastic sample. Three-dimensional hyperspectral data, comprising two-dimensional B-mode images and a third dimension corresponding to vibration frequency, were acquired from samples undergoing external mechanical excitation in the audio-frequency range. We describe the optical coherence tomography (OCT) signal when vibration is applied to a sample and detail the processing and acquisition techniques used to extract the local complex mechanical response from three-dimensional data that, due to a wide range of vibration frequencies, possess a wide range of sample velocities. We demonstrate frequency-dependent contrast of the displacement amplitude and phase of a silicone phantom containing inclusions of higher stiffness. Measurements of an ex vivo tumor margin demonstrate distinct spectra between adipose and tumor regions, and images of displacement amplitude and phase demonstrated spatially-resolved contrast. Contrast was also observed in displacement amplitude and phase images of a rat muscle sample. These results represent the first demonstration of mechanical spectroscopy based on B-mode OCT imaging. Spectroscopic optical coherence elastography (S-OCE) provides a high-resolution imaging capability for the detection of tissue pathologies that are characterized by a frequency-dependent viscoelastic response. PMID:21164898

  18. Spectroscopic Parameters for Ozone and its Isotopes: Current Status, Prospects for Improvement, and the Identification of 16O16O17O and O-16O-16O-17 and O-16O-17O-16 Lines in Infrared Ground-Based and Stratospheric Solar Absorption Spectra

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Flaud, J.-M.; Goldman, A.; Perrin, A.; Camy-Peyret, C.; Smith, M. A. H.; Devi, V. Malathy; Benner, D. C.; Barbe, A.; Stephens, T. M.; Murcray, F. J.

    1998-01-01

    We describe the updates to the spectroscopic parameters of ozone and its isotopes in the 1996 HITRAN compilation. Recent published studies not included in HITRAN are also summarized. Finally, we report the identification of infrared lines of the v(sub 3) bands of O-16O-16O-17 and O-16O-17O-16 in high-resolution solar spectra recorded by stratospheric balloon-borne and ground-based Fourier transform spectrometers.

  19. Spectroscopic Observations of Nearby Low Mass Stars

    NASA Astrophysics Data System (ADS)

    Vican, Laura; Zuckerman, B. M.; Rodriguez, D.

    2014-01-01

    Young low-mass stars are known to be bright in X-ray and UV due to a high level of magnetic activity. By cross-correlating the GALEX Catalog with the WISE and 2MASS Point Source Catalogs, we have identified more than 2,000 stars whose UV excesses suggest ages in the 10-100 Myr range. We used the Shane 3-m telescope at Lick Observatory on Mount Hamilton, California to observe some of these 2,000 stars spectroscopically. We measured the equivalent width of lithium at 6708 A absorption and H-alpha emission lines. Out of a total of 122 stars observed with the Kast grating spectrometer, we find that roughly 10% have strong lithium absorption features. The high percentage of stars with lithium present is further evidence of the importance of UV emission as a youth indicator for low-mass stars. In addition, we used high-resolution spectra obtained with the Hamilton echelle spectrograph to determine radial velocities for several UV-bright stars. These radial velocities will be useful for the calculation of Galactic UVW space velocities for determination of possible moving group membership. This work is supported by NASA Astrophysics Data Analysis Program award NNX12AH37G to RIT and UCLA and Chilean FONDECYT grant 3130520 to Universidad de Chile. This submission presents work for the GALNYSS project and should be linked to abstracts submitted by David Rodriguez, Laura Vican, and Joel Kastner.

  20. Fabrication of multi-layered absorption structure for high quantum efficiency photon detectors

    SciTech Connect

    Fujii, Go; Fukuda, Daiji; Numata, Takayuki; Yoshizawa, Akio; Tsuchida, Hidemi; Fujino, Hidetoshi; Ishii, Hiroyuki; Itatani, Taro; Zama, Tatsuya; Inoue, Shuichiro

    2009-12-16

    We report on some efforts to improve a quantum efficiency of titanium-based optical superconducting transition edge sensors using the multi-layered absorption structure for maximizing photon absorption in the Ti layer. Using complex refractive index values of each film measured by a Spectroscopic Ellipsometry, we designed and optimized by a simulation code. An absorption measurement of fabricated structure was in good agreement with the design and was higher than 99% at optimized wavelength of 1550 nm.

  1. Investigation of the spectroscopic features of clay-rich rocks in terms of geo-mechanical evaluations

    NASA Astrophysics Data System (ADS)

    Nefeslioglu, Hakan A.

    2013-04-01

    The main purpose of this study is to investigate the spectroscopic features of clay-rich rocks in terms of geo-mechanical evaluations. For the purpose, different types of sedimentary rocks including claystones and mudstones were used. Ultra sonic pulse velocity (Vp) measurements and Uniaxial Compressive Strength (UCS) tests were carried out by using the core samples of these clay-rich rocks, and moduli of elasticity (Ei) values of the samples were calculated. Spectroscopic measurements were also done by using the failed core samples. According to the spectral feature search analyses of the samples 7 spectral bands were differentiated depending on crystal filed effects and charge transfer absorptions of transition elements and water and OH vibrational features. Considering these 7 spectral bands, 8 different genetic rock types were defined. The regression equations of Vp-UCS and Vp-Ei were evaluated for the unclassified and genetic rock types, respectively. The coefficients of correlations of the equations became considerably higher when the genetic rock types were considered, and the equations were found to be statistically significant.

  2. D-xylose absorption

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003606.htm D-xylose absorption To use the sharing features on this page, please enable JavaScript. D-xylose absorption is a laboratory test to determine ...

  3. The spectroscopic foundation of CO2 climate forcing

    NASA Astrophysics Data System (ADS)

    Mlynczak, M. G.; Daniels, T.; Kratz, D. P.; Collins, W.; Feldman, D.; Lawler, J. E.; Anderson, L. W.; Fahey, D. W.; Hunt, L. A.

    2015-12-01

    The radiative forcing (RF) of carbon dioxide (CO2) is the leading contribution to climate change from anthropogenic activities. Calculating CO2 RF requires detailed knowledge of spectral line parameters and lineshape functions for thousands of infrared absorption lines. A reliable spectroscopic characterization of CO2 forcing is therefore a critical input to scientific and policy-oriented assessments of present climate and future climate change. Our study is partly motivated by a recent assertion that CO2 RF values, and hence predictions of climate sensitivity to elevated CO2, have a significant high bias because the CO2 spectroscopic parameters being used are incorrect. Our results show that CO2 RF in a variety of atmospheres is remarkably insensitive to known uncertainties in the three main CO2 spectroscopic parameters: the line strengths, half widths, and line shapes. We demonstrate that this is due largely to the definition of CO2 RF, which is the difference between the CO2 longwave net flux at the tropopause for doubled CO2 concentrations from the preindustrial era. We also assess the effects of sub-Lorentzian wings of CO2 lines and find that the computed RF is largely insensitive to the spectral lineshape function. Overall, the spectroscopic uncertainty in present-day CO2 RF is less than a few percent. Our study highlights the basics and subtleties of RF calculations, addressing interests of the expert and non-expert.

  4. Enhancing forensic science with spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Ricci, Camilla; Kazarian, Sergei G.

    2006-09-01

    This presentation outlines the research we are developing in the area of Fourier Transform Infrared (FTIR) spectroscopic imaging with the focus on materials of forensic interest. FTIR spectroscopic imaging has recently emerged as a powerful tool for characterisation of heterogeneous materials. FTIR imaging relies on the ability of the military-developed infrared array detector to simultaneously measure spectra from thousands of different locations in a sample. Recently developed application of FTIR imaging using an ATR (Attenuated Total Reflection) mode has demonstrated the ability of this method to achieve spatial resolution beyond the diffraction limit of infrared light in air. Chemical visualisation with enhanced spatial resolution in micro-ATR mode broadens the range of materials studied with FTIR imaging with applications to pharmaceutical formulations or biological samples. Macro-ATR imaging has also been developed for chemical imaging analysis of large surface area samples and was applied to analyse the surface of human skin (e.g. finger), counterfeit tablets, textile materials (clothing), etc. This approach demonstrated the ability of this imaging method to detect trace materials attached to the surface of the skin. This may also prove as a valuable tool in detection of traces of explosives left or trapped on the surfaces of different materials. This FTIR imaging method is substantially superior to many of the other imaging methods due to inherent chemical specificity of infrared spectroscopy and fast acquisition times of this technique. Our preliminary data demonstrated that this methodology will provide the means to non-destructive detection method that could relate evidence to its source. This will be important in a wider crime prevention programme. In summary, intrinsic chemical specificity and enhanced visualising capability of FTIR spectroscopic imaging open a window of opportunities for counter-terrorism and crime-fighting, with applications ranging

  5. The spectroscopic foundation of radiative forcing of climate by carbon dioxide

    NASA Astrophysics Data System (ADS)

    Mlynczak, Martin G.; Daniels, Taumi S.; Kratz, David P.; Feldman, Daniel R.; Collins, William D.; Mlawer, Eli J.; Alvarado, Matthew J.; Lawler, James E.; Anderson, L. W.; Fahey, David W.; Hunt, Linda A.; Mast, Jeffrey C.

    2016-05-01

    The radiative forcing (RF) of carbon dioxide (CO2) is the leading contribution to climate change from anthropogenic activities. Calculating CO2 RF requires detailed knowledge of spectral line parameters for thousands of infrared absorption lines. A reliable spectroscopic characterization of CO2 forcing is critical to scientific and policy assessments of present climate and climate change. Our results show that CO2 RF in a variety of atmospheres is remarkably insensitive to known uncertainties in the three main CO2 spectroscopic parameters: the line shapes, line strengths, and half widths. We specifically examine uncertainty in RF due to line mixing as this process is critical in determining line shapes in the far wings of CO2 absorption lines. RF computed with a Voigt line shape is also examined. Overall, the spectroscopic uncertainty in present-day CO2 RF is less than 1%, indicating a robust foundation in our understanding of how rising CO2 warms the climate system.

  6. CD-ROM Spectroscope: A Simple and Inexpensive Tool for Classroom Demonstrations on Chemical Spectroscopy.

    ERIC Educational Resources Information Center

    Wakabayashi, Fumitaka; Hamada, Kiyohito; Sone, Kozo

    1998-01-01

    Describes the construction and use of a spectroscope using a compact disk as a reflection grating. Lists instructions for viewing emission spectra of white or fluorescent light sources or discharge tubes, and absorption spectra of colored solutions. Includes modified directions and expanded activities. Contains 16 references. (WRM)

  7. Gold analysis by the gamma absorption technique.

    PubMed

    Kurtoglu, Arzu; Tugrul, A Beril

    2003-01-01

    Gold (Au) analyses are generally performed using destructive techniques. In this study, the Gamma Absorption Technique has been employed for gold analysis. A series of different gold alloys of known gold content were analysed and a calibration curve was obtained. This curve was then used for the analysis of unknown samples. Gold analyses can be made non-destructively, easily and quickly by the gamma absorption technique. The mass attenuation coefficients of the alloys were measured around the K-shell absorption edge of Au. Theoretical mass attenuation coefficient values were obtained using the WinXCom program and comparison of the experimental results with the theoretical values showed generally good and acceptable agreement. PMID:12485656

  8. Synthesis, spectroscopic, thermal and antimicrobial investigations of charge-transfer complexes formed from the drug procaine hydrochloride with quinol, picric acid and TCNQ

    NASA Astrophysics Data System (ADS)

    Adam, Abdel Majid A.

    2012-12-01

    Intermolecular charge-transfer or proton-transfer complexes between the drug procaine hydrochloride (PC-HCl) as a donor and quinol (QL), picric acid (PA) or 7,7',8,8'-tetracyanoquinodimethane (TCNQ) as a π-acceptor have been synthesized and spectroscopically studied in methanol at room temperature. Based on elemental analyses and photometric titrations, the stoichiometry of the complexes (donor:acceptor molar ratios) was determined to be 1:1 for all three complexes. The formation constant (KCT), molar extinction coefficient (ɛCT) and other spectroscopic data have been determined using the Benesi-Hildebrand method and its modifications. The newly synthesized CT complexes have been characterized via elemental analysis, IR, Raman, 1H NMR, and electronic absorption spectroscopy. The morphological features of these complexes were investigated using scanning electron microscopy (SEM), and the sharp, well-defined Bragg reflections at specific 2θ angles have been identified from the powder X-ray diffraction patterns. Thermogravimetric analyses (TGAs) and kinetic thermodynamic parameters were also used to investigate the thermal stability of the synthesized solid CT complexes. Finally, the CT complexes were screened for their antibacterial and antifungal activities against various bacterial and fungal strains, and only the complex obtained using picric acid exhibited moderate antibacterial activity against all of the tested strains.

  9. Spectroscopic data for thermal infrared remote sensing

    NASA Technical Reports Server (NTRS)

    Varanasi, P.; Nemtchinov, V.; Li, Z.

    1995-01-01

    There has been extensive world-wide use of chloro-fluoro-carbons (CFC's), especially CFC-11 (CFCl3) and CFC-12 (CF2Cl2), hydro-chloro-fluoro-carbons (HCFC's), HCFC-22 (CHFCl2) in particular, and sulphur hexaflouride (SF6) in numerous many industrial applications. These chemicals possess either a strong ozone-depletion potential or a global-warming potential, or both, and pose a threat to the inhabitability of our planet. Recognition of this fact has led to significant curtailment, if not total banishment, of their use globally. However, as recent satellite observations have shown, decline in their atmospheric concentrations may not be immediate. The marked depletion of ozone which has been observed in recent years at high latitudes has made infrared remote sensing of the atmosphere an activity of high priority. The success of any infrared remote sensing experiment conducted in the atmosphere depends upon the availability of accurate, high-resolution, spectroscopic data that are applicable to that experiment. This paper presents a preliminary phase of a multi-faceted work using a Fourier-transform spectrometer (FTS) which is in progress in our laboratory. The concept of how laboratory-borne measurements can be geared toward obtaining a database that is directly applicable to satellite-borne remote sensing missions is the main thrust of this paper which addresses itself to ongoing or planned international space missions. Spectroscopic data on the unresolvable bands of the above mentioned as well as several other man-made gases and on the individual spectral lines of such naturally present trace gases as CO2, N2O, NH3, and CH4 are presented. There is often significant overlap between the isolated lines of better known bands of the more abundant species and the weaker absorption features identifiable as bands of the currently less abundant CFC's, HCFC's, and SF6.

  10. Water-related absorption in fibrous diamonds

    NASA Astrophysics Data System (ADS)

    Zedgenizov, D. A.; Shiryaev, A. A.; Kagi, H.; Navon, O.

    2003-04-01

    Cubic and coated diamonds from several localities (Brasil, Canada, Yakutia) were investigated using spectroscopic techniques. Special emphasis was put on investigation of water-related features of transmission Infra-red and Raman spectra. Presence of molecular water is inferred from broad absorption bands in IR at 3420 and 1640 cm-1. These bands were observed in many of the investigated samples. It is likely that molecular water is present in microinclusions in liquid state, since no clear indications of solid H_2O (ice VI-VII, Kagi et al., 2000) were found. Comparison of absorption by HOH and OH vibrations shows that diamonds can be separated into two principal groups: those containing liquid water (direct proportionality of OH and HOH absorption) and those with stronger absorption by OH group. Fraction of diamonds in every group depends on their provenance. There might be positive correlation between internal pressure in microinclusions (determined using quartz barometer, Navon et al., 1988) and affiliation with diamonds containing liquid water. In many cases absorption by HOH vibration is considerably lower than absorption by hydroxyl (OH) group. This may be explained if OH groups are partially present in mineral and/or melt inclusions. This hypothesis is supported by following fact: in diamonds with strong absorption by silicates and other minerals shape and position of the OH band differs from that in diamonds with low absorption by minerals. Moreover, in Raman spectra of individual inclusions sometimes the broad band at 3100 cm-1 is observed. This band is OH-related. In some samples water distribution is not homogeneous. Central part of the diamond usually contains more water than outer parts, but this is not a general rule for all the samples. Water absorption usually correlated with absorption of other components (carbonates, silicates and others). At that fibrous diamonds with relatively high content of silicates are characterized by molecular water. OH

  11. Advanced laser stratospheric monitoring systems analyses

    NASA Technical Reports Server (NTRS)

    Larsen, J. C.

    1984-01-01

    This report describes the software support supplied by Systems and Applied Sciences Corporation for the study of Advanced Laser Stratospheric Monitoring Systems Analyses under contract No. NAS1-15806. This report discusses improvements to the Langley spectroscopic data base, development of LHS instrument control software and data analyses and validation software. The effect of diurnal variations on the retrieved concentrations of NO, NO2 and C L O from a space and balloon borne measurement platform are discussed along with the selection of optimum IF channels for sensing stratospheric species from space.

  12. CO2 Absorption Spectroscopy and Climate Change

    NASA Astrophysics Data System (ADS)

    Feldman, Daniel; Mlawer, Eli; Mlynczak, Martin; Gero, Jon; Collins, William; Torn, Margaret

    2014-03-01

    Most of the absorption, and therefore radiative forcing, due to increased atmospheric CO2 occurs in line wings, so utilizing an accurate line shape is necessary for climate science. Recent advances in CO2 absorption spectroscopy have been incorporated into benchmark line-by-line radiative transfer models. These updates include the Energy Corrected Sudden Approximation to represent isolated line profiles, line mixing, and line clusters. The CO2 line profiles are sub-Lorentzian and are explicitly modeled up to 25 cm-1 from each line's center. Consistent continuum absorption is implemented over the remainder of the profile except for modest empirical adjustments based on observations. Thus, line-by-line models calculate the absorption effects of CO2 that agree with theory and measurements. This is validated with long-term spectroscopic measurements from the ARM program's AERI instrument. This spectroscopy trains computationally-efficient correlated-k methods for climate model radiative transfer, but they overpredict instantaneous radiative forcing from doubled CO2 by approximately 7% in part because they have larger errors handling the impact of increased CO2 in the stratosphere than the troposphere. The implications of this can be tested with supercomputers. This work was supported by the Director, Office of Science, Office of Biol. & Env. Res., Clim. & Env. Sci. Div., of the U.S. D.O.E., Contract No. DE-AC02-05CH11231 as part of the Atmos. Sys. Res.

  13. Spectroscopic Investigation of Ce(3+) Doped Fluoride Crystals

    NASA Technical Reports Server (NTRS)

    Reinhart, Donald H.; Armagan, Guzin; Marsh, Waverly; Barnes, James; Chai, B. H. T.

    1995-01-01

    Doping of the trivalent rare-earth cerium ion into fluoride crystals is of interest in producing turnable ultra-violet solid state lasers. These lasers are desirable for many applications in medicine, industry, and scientific research, including remote sensing. High absorption and stimulated emission cross sections of the dipole allowed 4f-5d transitions show promise in cerium as a laser ion in crystals. Several research groups have already reported the observation of stimulated emission of cerium in LiYF4, LiSrAlF6, and LiCaAlF6. However, the color center formation in the crystals due to the excited state absorption of ultra-violet pump light adds difficulty to achieving laser action. We have investigated the spectroscopic properties of cerium such as absorption and emission spectra, and lifetimes in four different fluoride crystals, including LiCaAlF6, LiSrAlF6, KyF4 and LiYF4. We have derived the polarized absorption and stimulated emission cross sections from transmission and fluorescence emission measurements for each of the host crystals. we have measured the lifetime of the lowest 5d level; moreover, investigated the temperature dependence of this lifetime and color center formation. Our results on absorption and stimulated emission cross sections for LiCaAlF6 and LiSrAlF6 are similar to the results already published.

  14. A DVD Spectroscope: A Simple, High-Resolution Classroom Spectroscope

    ERIC Educational Resources Information Center

    Wakabayashi, Fumitaka; Hamada, Kiyohito

    2006-01-01

    Digital versatile disks (DVDs) have successfully made up an inexpensive but high-resolution spectroscope suitable for classroom experiments that can easily be made with common material and gives clear and fine spectra of various light sources and colored material. The observed spectra can be photographed with a digital camera, and such images can…

  15. Spectroscopic evidence for Davydov-like solitons in acetanilide

    NASA Astrophysics Data System (ADS)

    Careri, G.; Buontempo, U.; Galluzzi, F.; Scott, A. C.; Gratton, E.; Shyamsunder, E.

    1984-10-01

    Detailed measurements of infrared absorption and Raman scattering on crystalline acetanilide [(CH3CONHC6H5)x] at low temperature show a new band close to the conventional amide I band. Equilibrium properties and spectroscopic data rule out explanations based on a conventional assignment, crystal defects, Fermi resonance, and upon frozen kinetics between two different subsystems. Thus we cannot account for this band using the concepts of conventional molecular spectroscopy, but a soliton model, similar to that proposed by Davydov for α-helix in protein, is in satisfactory agreement with the experimental data.

  16. The GEISA spectroscopic line parameters data bank in 1984

    NASA Technical Reports Server (NTRS)

    Husson, N.; Chedin, A.; Scott, N. A.; Bailly, D.; Graner, G.; Lacome, N.; Brown, L. R.; Orton, G.; Rinsland, C. P.; Smith, M. A. H.

    1986-01-01

    The 1984 update of the GEISA data bank, containing spectroscopic information on 323,521 lines corresponding to 36 molecules and 79 isotopic species in the spectal range 3 x 10 to the -6th/cm to 17,879/cm, is discussed. The bank compiles parameters describing the radiation absorption or emission properties of gases involved in the atmospheres of the earth and planets. Values of a new exponent which summarized the variation of the collision halfwidth with temperature are given for 10 molecules. Six new molecules, HOCl, N2, CH3Cl, H2O2, H2S, and HCOOH, are included in this edition.

  17. Spectroscopic properties of vitamin E models in solution

    NASA Astrophysics Data System (ADS)

    Oliveira, L. B. A.; Colherinhas, G.; Fonseca, T. L.; Castro, M. A.

    2015-05-01

    We investigate the first absorption band and the 13C and 17O magnetic shieldings of vitamin E models in chloroform and in water using the S-MC/QM methodology in combination with the TD-DFT and GIAO approaches. The results show that the solvent effects on these spectroscopic properties are small but a proper description of the solvent shift for 17O magnetic shielding of the hydroxyl group in water requires the use of explicit solute-solvent hydrogen bonds. In addition, the effect of the replacement of hydrogen atoms by methyl groups in the vitamin E models only affects magnetic shieldings.

  18. Potassium emission absorption system. Topical report 12

    SciTech Connect

    Bauman, L.E.

    1995-04-01

    The Potassium Emission Absorption System is one of the advanced optical diagnostics developed at Mississippi State University to provide support for the demonstration of prototype-scale coal-fired combustion magnetohydrodynamic (MHD) electrical power generation. Intended for application in the upstream of an MHD flow, the system directly measures gas temperature and neutral potassium atom number density through spectroscopic emission absorption techniques. From these measurements the electron density can be inferred from a statistical equilibrium calculation and the electron conductivity in the MHD channel found by use of an electron mobility model. The instrument has been utilized for field test measurements on MHD facilities for almost a decade and has been proven to provide useful measurements as designed for MHD nozzle, channel, and diffuser test sections. The theory of the measurements, a system description, its capabilities, and field test measurement results are reported here. During the development and application of the instrument several technical issues arose which when addressed advanced the state of the art in emission absorption measurement. Studies of these issues are also reported here and include: two-wavelength measurements for particle-laden flows, potassium D-line far wing absorption coefficient, bias in emission absorption measurements arising from dirty windows and misalignments, non-coincident multiwavelength emission absorption sampling errors, and lineshape fitting for boundary layer flow profile information. Although developed for NLHD application, the instrument could be applied to any high temperature flow with a resonance line in the 300 to 800 nm range, for instance other types of flames, rocket plumes or low temperature plasmas.

  19. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Arora, Deepawali; Kumar, Sunil; Singh, D. P.

    2016-08-01

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV-Vis absorption spectra and fluorescence spectra (λexc.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO4 units thus supporting the density results. The UV- Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  20. Characterization of minerals in air dust particles in the state of Tamilnadu, India through FTIR, XRD and SEM analyses

    NASA Astrophysics Data System (ADS)

    Senthil Kumar, R.; Rajkumar, P.

    2014-11-01

    The abstract of this paper explains the presence of minerals in air which causes great concern regarding public health issues. The spectroscopic investigation of air dust particles of several samples in various locations in the state of Tamilnadu, India is reported. Qualitative analyses were carried out to determine the major and minor constituent minerals present in the samples based on the FTIR, XRD absorption peaks. This study also identified the minerals like quartz, asbestos, kaolinite, calcite, hematite, montmorillonite, nacrite and several other trace minerals in the air dust particles. The presents of quartz is mainly found in all the samples invariably. Hence the percentage of quartz and its crystalline nature were determined with the help of extinction co-efficient and crystallinity index respectively. The shape and size of the particulates are studied with SEM analysis.

  1. X-ray absorption spectroscopy of chicken sulfite oxidase crystals

    SciTech Connect

    George, G.N.; Pickering, I.J.; Kisker, C.

    1999-05-17

    Sulfite oxidase catalyzes the physiologically vital oxidation of sulfite to sulfate. Recently, the crystal structure of chicken sulfite oxidase has been reported at 1.9 {angstrom} resolution. In contrast to the information available from previous X-ray absorption spectroscopic studies, the active site indicated by crystallography was a mono-oxo species. Because of this the possibility that the crystals did in fact contain a reduced molybdenum species was considered in the crystallographic work. The authors report herein an X-ray absorption spectroscopic study of polycrystalline sulfite oxidase prepared in the same manner as the previous single-crystal samples, and compare this with data for frozen solutions of oxidized and reduced enzyme.

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

    NASA Technical Reports Server (NTRS)

    deGroot, Wim; Opila, Beth

    2001-01-01

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

  3. Gold nanoparticles assisted structural and spectroscopic modification in Er3+-doped zinc sodium tellurite glass

    NASA Astrophysics Data System (ADS)

    Awang, Asmahani; Ghoshal, S. K.; Sahar, M. R.; Arifin, R.

    2015-04-01

    Achieving enhanced spectroscopic properties of rare earth doped inorganic glasses by embedding metallic nanoparticles of controlled sizes is a challenging task. We report the gold (Au) NPs assisted modifications in structural and spectroscopic properties of melt-quench synthesized Er3+ doped zinc sodium tellurite glass. The growth of NPs is stimulated via time varying heat treatment at 300 °C. XRD patterns confirm the amorphous nature of glasses and TEM images manifest the growth of gold NPs with sizes between 6.1 and 10.7 nm. The heat treatment time dependent variations in physical properties are ascribed to the alteration in bonding of non-bridging oxygen ions. The UV-VIS-NIR spectra reveal six absorption peaks centered at 488, 523, 655, 800, 973 and 1533 nm corresponding to the transition from ground state of 4I15/2 to 4F7/2, 2H11/2, 4F9/2, 4I9/2,4I11/2, and 4I13/2 excited states of Er3+ ions, respectively. Surface plasmon resonance (SPR) bands are observed in the range of 618-632 nm. Judd-Ofelt analyses demonstrate a significant increase of spectroscopic quality factors (0.86-1.05) and branching ratio (0.62-92.38%). The up-conversion emission spectra of Er3+ exhibit three prominent peaks of reasonable green (502 nm), a moderate green (546 nm) and a strong red (629 nm). An enhancement in the red band luminescence intensity by a factor of 8.19 and 8.54 times are achieved for 2 and 4 h of heat treatments, respectively. This enhancement is attributed to the SPR effects of gold NPs producing an intense local field in the proximity of Er3+ ions and subsequent energy transfer between RE ions and NPs. The FTIR spectra display the presence of vibrational modes for ZnO4 bonds, Te-O bond in TeO3 (tp) and TeO4 (tbp) units and the hydroxyl groups. Excellent features of the results suggest that our method constitute a basis for tunable growth of gold NPs which is exceedingly useful for the optimization of optical and structural properties.

  4. Spectroscopic observations of the dwarf nova IP Pegasi

    SciTech Connect

    Hessman, F.V. )

    1989-08-01

    Time-resolved spectroscopic measurements of IP Peg were obtained immediately after a dwarf nova eruption. The radio-velocity amplitude of the white dwarf (118 + or - 10 km/s) implied by measurements from the wings of the Balmer emission lines is different from that found previously. The results suggest a mass ratio M1/M2 of 0.435 + or - 0.052 and that the narrow component is due to unusually strong chromospheric emission from the late-type star. The low value for the radial-velocity amplitude of this narrow emission (about 200 km/s) is consistent with the observed absorption-line amplitude of 331 km/s if the irradiated surface of the M dwarf produces little line absorption. 40 refs.

  5. Spectroscopic intravascular photoacoustic imaging of neovasculature: phantom studies

    NASA Astrophysics Data System (ADS)

    Su, Jimmy L.; Wang, Bo; Emelianov, Stanislav Y.

    2009-02-01

    An acceleration of angiogenesis in the adventitial vasa-vasorum is usually associated with vulnerable, thin-cap fibroatheroma in atherosclerotic plaques. Angiogenesis creates microvasculature too small to be detected and differentiated using conventional imaging techniques. However, by using spectroscopic photoacoustic imaging, we take advantage of the wavelength-dependent optical absorption properties of blood. We used a vessel-mimicking phantom with micro blood vessels. The phantom was imaged with intravascular photoacoustic imaging across a range of wavelengths. The image intensities were cross-correlated with the known absorption spectra of blood. The resulting cross-correlation image was able to reveal the location of the artificial blood vessels differentiated from non-blood vessel components.

  6. Synthesis, structure, spectroscopic and electrochemical properties of bis(histamine-saccharinate) copper(II) complex

    NASA Astrophysics Data System (ADS)

    Bulut, İclal; Uçar, İbrahim; Karabulut, Bünyamin; Bulut, Ahmet

    2007-05-01

    Crystal structure of [Cu(hsm) 2(sac) 2] (hsm is histamine and sac is saccharinate) complex has been determined by X-ray diffraction analyses and its magnetic environment has been identified by electron paramagnetic resonance (EPR) technique. The title complex crystallizes in the monoclinic system, space group P 21/ c with a = 7.4282(4), b = 22.5034(16), c = 8.3300(5) Å, β = 106.227(4)°, V = 1336.98(14) Å 3, and Z = 2. The structure consist of discrete [Cu(hsm) 2(sac) 2] molecules in which the copper ion is centrosymmetrically coordinated by two histamine ligands forming an equatorial plane [Cu-N hsm = 2.024(2) and Cu-N hsm = 2.0338(18) Å]. Two N atoms from the saccharinate ligands coordinate on the elongated axial positions with Cu-N sac being 2.609(5) Å. The complex is also characterized by spectroscopic (IR, UV/Vis) and thermal (TG, and TDA) methods. The cyclic voltammogram of the title complex investigated in DMSO (dimethylsulfoxide) solution exhibits only metal centred electroactivity in the potential range - 1.25-1.5 V versus Ag/AgCl reference electrode. The molecular orbital bond coefficients of Cu(II) ion in d 9 state is also calculated by using EPR and optical absorption parameters.

  7. Red to Near-Infrared Isoindole BODIPY Fluorophores: Synthesis, Crystal Structures, and Spectroscopic and Electrochemical Properties.

    PubMed

    Yu, Changjiang; Wu, Qinghua; Wang, Jun; Wei, Yun; Hao, Erhong; Jiao, Lijuan

    2016-05-01

    A series of high-performance fluorophores named isoindole boron dipyrromethenes (BODIPYs) containing either symmetrical or unsymmetrical alkyl substitution patterns on pyrrole rings were synthesized by an efficient process and were characterized by X-ray diffraction and spectroscopic and electrochemical analyses. Most of these dyes show strong, sharp absorption and bright fluorescence emission in the red to near-infrared (NIR) region (up to 805 nm in acetonitrile). Pyrrolic alkyl substitutions lead to increases in the HOMO and LUMO energy levels and an overall decrease in the energy band gaps of the dye. Among the 23 isoindole BODIPY dyes synthesized, solvent-dependent fluorescence emission and lifetime decay were only observed for those containing a 3-methyl substituent on the uncoordinated pyrrole ring, whereas little variation in the fluorescence intensity was observed for the rest of the dyes upon changing the polarity of the solvent. These resultant dyes can be further functionalized via the Knoevenagel condensation on the α-methyl substituent of the chromophore to install a variety of functionalities, including a dimethylamine group demonstrated in this work. This dimethylamine-functionalized isoindole BODIPY shows weak fluorescence at 805 nm in acetonitrile and a ratiometric "turn-on" NIR fluorescence response to decreasing pH. PMID:27031115

  8. CD-ROM Spectroscope: A Simple and Inexpensive Tool for Classroom Demonstrations on Chemical Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wakabayashi, Fumitaka; Hamada, Kiyohito; Sone, Kozo

    1998-12-01

    Construction of a handy spectroscope using a compact disk (CD) or a CD-ROM and its application to the observation of emission and absorption spectra are described. Using this simple cardboard-made spectroscope, one can readily observe line emission spectra of fluorescent lamps, gas discharge tubes, etc. The spectroscope is also used to observe the absorption spectra of colored solutions; the absorption bands are observed as distinct black bands on the rainbow-colored continuous spectrum of an incandescent lamp. The results for the aqueous solution of potassium permanganate, the methanol and ethanol solutions of cobalt chloride, and Fe(III)-thiocyanate complex are described. These results clearly show the general rule that a colored solution absorbs the complementary color of the color of the solution. Thus, the CD-ROM spectroscope is a useful tool in primary and secondary schools to teach what color is and what spectra are. Furthermore, it can be used effectively in introductory courses in colleges and universities to teach that spectra are really beautiful natural phenomena which can be observed simply.

  9. Solar absorption surface panel

    DOEpatents

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  10. Spectroscopic investigations of HBV 475 in optical regions

    SciTech Connect

    Tamura, Shinichi )

    1989-03-01

    High-resolution spectroscopic analyses of HBV 475 are presented based on emission-line profiles of H-alpha, H-gamma, He I 4921-A, He I 5016-A, forbidden O III 4959-A, 5007-A, Fe II 5018-A, and Fe II 4924-A. Radial-velocity analyses show that only a part of the line components coincides well with previous measurements. Other remarkable components are found which are shifted to either the violet or red sides, depending on the indicated phase. Highly resolved emission-line profiles reveal that they are not compatible with the calculated profiles of proposed theoretical models. 21 refs.

  11. Petawatt laser absorption bounded

    PubMed Central

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-01-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

  12. Petawatt laser absorption bounded

    NASA Astrophysics Data System (ADS)

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-06-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials.

  13. Bridging the gap between macroscopic and spectroscopic studies of metal ion sorption at the oxide/water interface: Sr(II), Co(II), and Pb(II) sorption to quartz.

    PubMed

    Chen, Chia-Chen; Coleman, Michael L; Katz, Lynn E

    2006-01-01

    Metal sorption mechanisms were investigated for strontium, cobalt, and lead using sodium chloride, sodium nitrate, and sodium perchlorate as background electrolytes and quartz as the adsorbent. Spectroscopic analyses of concentrated sorption samples were evaluated for their ability to provide insight into the controlling sorption process for more dilute systems. For strontium, outer-sphere complexes identified using X-ray absorption spectroscopy (XAS) of concentrated samples were consistent with macroscopic sorption data collected in more dilute systems. XAS results indicated that cobalt formed a new solid phase upon sorption to silica. Macroscopic studies of cobalt sorption supported the spectroscopic data for total cobalt concentrations of 10(-5) M, regardless of the background electrolyte composition or concentration. At a lower total cobalt concentration (10(-7) M), adsorption appeared to be the prevailing mechanism of cobalt removal. Spectroscopic results suggested that lead adsorbed as an inner-sphere complex on silica. The decrease of lead removal with increasing chloride concentration was attributed to competition with aqueous lead-chloride complexes, based on thermodynamic calculations. PMID:16433344

  14. Percutaneous absorption of drugs.

    PubMed

    Wester, R C; Maibach, H I

    1992-10-01

    The skin is an evolutionary masterpiece of living tissue which is the final control unit for determining the local and systemic availability of any drug which must pass into and through it. In vivo in humans, many factors will affect the absorption of drugs. These include individual biological variation and may be influenced by race. The skin site of the body will also influence percutaneous absorption. Generally, those body parts exposed to the open environment (and to cosmetics, drugs and hazardous toxic substances) are most affected. Treating patients may involve single daily drug treatment or multiple daily administration. Finally, the body will be washed (normal daily process or when there is concern about skin decontamination) and this will influence percutaneous absorption. The vehicle of a drug will affect release of drug to skin. On skin, the interrelationships of this form of administration involve drug concentration, surface area exposed, frequency and time of exposure. These interrelationships determine percutaneous absorption. Accounting for all the drug administered is desirable in controlled studies. The bioavailability of the drug then is assessed in relationship to its efficacy and toxicity in drug development. There are methods, both quantitative and qualitative, in vitro and in vivo, for studying percutaneous absorption of drugs. Animal models are substituted for humans to determine percutaneous absorption. Each of these methods thus becomes a factor in determining percutaneous absorption because they predict absorption in humans. The relevance of these predictions to humans in vivo is of intense research interest. The most relevant determination of percutaneous absorption of a drug in humans is when the drug in its approved formulation is applied in vivo to humans in the intended clinical situation. Deviation from this scenario involves the introduction of variables which may alter percutaneous absorption. PMID:1296607

  15. Spectroscopic features of cytochrome P450 reaction intermediates

    PubMed Central

    Luthra, Abhinav; Denisov, Ilia G.; Sligar, Stephen G.

    2010-01-01

    Preface Cytochromes P450 constitute a broad class of heme monooxygenase enzymes with more than 11,500 isozymes which have been identified in organisms from all biological kingdoms [1]. These enzymes are responsible for catalyzing dozens chemical oxidative transformations such as hydroxylation, epoxidation, N-demethylation, etc., with very broad range of substrates [2-3]. Historically these enzymes received their name from ‘pigment 450’ due to the unusual position of the Soret band in UV-Vis absorption spectra of the reduced CO-saturated state [4-5]. Despite detailed biochemical characterization of many isozymes, as well as later discoveries of other ‘P450-like heme enzymes’ such as nitric oxide synthase and chloroperoxidase, the phenomenological term ‘cytochrome P450’ is still commonly used as indicating an essential spectroscopic feature of the functionally active protein which is now known to be due to the presence of a thiolate ligand to the heme iron [6]. Heme proteins with an imidazole ligand such as myoglobin and hemoglobin as well as an inactive form of P450 are characterized by Soret maxima at 420 nm [7]. This historical perspective highlights the importance of spectroscopic methods for biochemical studies in general, and especially for heme enzymes, where the presence of the heme iron and porphyrin macrocycle provides rich variety of specific spectroscopic markers available for monitoring chemical transformations and transitions between active intermediates of catalytic cycle. PMID:21167809

  16. Characterization of semicrystalline polymers after nanoimprint by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Wang, Si; Rond, Johannes; Steinberg, Christian; Papenheim, Marc; Scheer, Hella-Christin

    2016-02-01

    Semicrystalline Reg-P3HT (regio-regular poly-3-hexylthiophene) is a promising material for organic electronics. It features relatively high charge mobility and enables easy preparation because of its solubility. Due to its high optical and electrical anisotropy, the size, number and orientation of the ordered domains are important for applications. To control these properties without limitation from crystalline domains existing after spin coating, thermal nanoimprint is performed beyond the melting point. The state of the art of measurement to analyze the complex morphology is X-ray diffraction (XRD). We address an alternative measurement method to characterize the material by its optical properties, spectroscopic ellipsometry. It provides information on the degree of order from the typical fingerprint absorption spectrum. In addition, when the material is modeled as a uniaxial layer, an anisotropy factor can be derived. The results obtained from spectroscopic ellipsometry are in accordance with those from XRD. In particular, spectroscopic ellipsometry is able to distinguish between order along the backbone and order in π- π stacking direction, which is important with respect to conductivity.

  17. Progress in laser-spectroscopic techniques for aerodynamic measurements - An overview

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert L.

    1991-01-01

    An overview is given of the capabilities and recent progress in laser-spectroscopic measurement techniques for use in aerodynamic test facilities and flight research vehicles. It includes a survey of the literature which is centered on this application of laser spectroscopy. The intended reader is the specialist in experimental fluid dynamics who is not intimately familiar with the physics or applications of laser spectroscopy. Thus, some discussion is also included of the nature of each laser-spectroscopic technique and the practical aspects of its use for aerodynamic measurements. The specific techniques reviewed include laser absorption, laser-induced fluorescence, laser Rayleigh scattering, and laser Raman scattering including spontaneous and coherent processes.

  18. Near-infrared spectroscopic photoacoustic microscopy using a multi-color fiber laser source

    PubMed Central

    Buma, Takashi; Wilkinson, Benjamin C.; Sheehan, Timothy C.

    2015-01-01

    We demonstrate a simple multi-wavelength optical source suitable for spectroscopic optical resolution photoacoustic microscopy (OR-PAM) of lipid-rich tissue. 1064 nm laser pulses are converted to multiple wavelengths beyond 1300 nm via nonlinear optical propagation in a birefringent optical fiber. OR-PAM experiments with lipid phantoms clearly show the expected absorption peak near 1210 nm. We believe this simple multi-color technique is a promising cost-effective approach to spectroscopic OR-PAM of lipid-rich tissue. PMID:26309746

  19. Far Ultraviolet Spectroscopic Explorer Measurements of Interstellar Fluorine

    NASA Astrophysics Data System (ADS)

    Federman, S. R.; Sheffer, Yaron; Lambert, David L.; Smith, V. V.

    2005-02-01

    The source of fluorine is not well understood, although core-collapse supernovae, Wolf-Rayet stars, and asymptotic giant branch stars have been suggested. A search for evidence of the ν-process during Type II supernovae is presented. Absorption from interstellar F I is seen in spectra of HD 208440 and HD 209339A acquired with the Far Ultraviolet Spectroscopic Explorer. In order to extract the column density for F I from the line at 954 Å, absorption from H2 has to be modeled and then removed. Our analysis indicates that for H2 column densities less than about 3×1020 cm-2, the amount of F I can be determined from λ954. For these two sight lines, there is no clear indication for enhanced F abundances resulting from the ν-process in a region shaped by past supernovae. Based on observations made with the NASA/CNES/CSA Far Ultraviolet Spectroscopic Explorer (FUSE), which is operated for NASA by the Johns Hopkins University under NASA contract NAS 5-32985.

  20. Molecular weight, polydispersity, and spectroscopic properties of aquatic humic substances

    USGS Publications Warehouse

    Chin, Y.-P.; Aiken, G.; O'Loughlin, E.

    1994-01-01

    The number- and weight-averaged molecular weights of a number of aquatic fulvic acids, a commercial humic acid, and unfractionated organic matter from four natural water samples were measured by high-pressure size exclusion chromatography (HPSEC). Molecular weights determined in this manner compared favorably with those values reported in the literature. Both recent literature values and our data indicate that these substances are smaller and less polydisperse than previously believed. Moreover, the molecular weights of the organic matter from three of the four natural water samples compared favorably to the fulvic acid samples extracted from similar environments. Bulk spectroscopic properties of the fulvic substances such as molar absorptivity at 280 nm and the E4/E6 ratio were also measured. A strong correlation was observed between molar absorptivity, total aromaticity, and the weight average molecular weights of all the humic substances. This observation suggests that bulk spectroscopic properties can be used to quickly estimate the size of humic substances and their aromatic contents. Both parameters are important with respect to understanding humic substance mobility and their propensity to react with both organic and inorganic pollutants. ?? 1994 American Chemical Society.

  1. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  2. Melt Structure and Properties: a Spectroscopic Perspective

    NASA Astrophysics Data System (ADS)

    Stebbins, J.

    2006-12-01

    Entropy, volume, and their P/T derivatives are at the heart of models of the thermodynamics of silicate melts and magmas. Quantitative characterization of glass structure is leading to important new insights into the links from "Microscopic to Macroscopic" that can at least guide interpretations of data and in some cases even have predictive power. A few recent examples will be discussed here. The often-large configurational components to heat capacities, thermal expansivities, and compressibilities of melts strongly indicate that structural changes with temperature and pressure are of key importance. At least some aspects of thermal increases in configurational (as opposed to vibrational) disorder are amenable to spectroscopic detection, either with in situ methods or on glasses with varying quench rates and thus varying fictive temperatures. In some systems, such changes are now clear, and can be shown to make significant contributions to properties. These include network cation coordination in systems such as borate liquids (BO4 to BO3 at higher T), and Al-Si disordering in aluminosilicates. In general, however, progress in this rich problem has only begun. It has long been suspected from thermodynamic analyses (and theoretical simulations) that configurational changes in melts play a key role in volume compression at high pressure, over and above that which can be expressed in "normal" equations of state or from those expected from bond compression and bending. Scattering and spectroscopic studies have revealed some of the important aspects of pressure-induced structural changes, but again we are just at the beginning of full understanding. For example, binary silicate glasses quenched from high-P melts clearly record some systematic increases in Si coordination, while aluminosilicates record systematic pressure and compositional (modifier cation field strength) effects on Al coordination in recovered samples with large, quenched-in density increases

  3. Spectroscopic characterization of polymers: report

    SciTech Connect

    Koenig, J.L.

    1987-10-01

    Polymer characterization has presented major difficulties to the analytical chemist, who has had to develop techniques to cope with the challenge. Even the elementary problem of measuring molecular weight is not easy. Yet such measurements are essential, because the physical, mechanical, and flow properties depend on the length of the polymer chain. Because of the limited solubility and high viscosity of polymers, many classical techniques have been of little use or have had to be extensively modified to measure the molecular weight of polymers. Size-exclusion chromatographic techniques such as gel permeation have been developed to measure these molecular weight distributions. Special chromatographic instruments with a range of spectroscopic detectors (including infrared and laser-light scattering) have emerged commercially to aid the analytical chemist in the fundamental endeavor to measure the length of the polymer chain and its distribution. The author describes the advantages and disadvantages and disadvantages of various spectroscopic techniques.

  4. Optimization of absorption air-conditioning for solar energy applications

    NASA Technical Reports Server (NTRS)

    Perry, E. H.

    1976-01-01

    Improved performance of solar cooling systems using the lithium bromide water absorption cycle is investigated. Included are computer simulations of a solar-cooled house, analyses and measurements of heat transfer rates in absorption system components, and design and fabrication of various system components. A survey of solar collector convection suppression methods is presented.

  5. Spectroscopic low coherence interferometry using a supercontinuum source and an ultra broadband spectrometer

    NASA Astrophysics Data System (ADS)

    Fleischhauer, F.; Caujolle, S.; Feutcher, T.; Rajendram, R.; Leick, L.; Podoleanu, A.

    2016-03-01

    Spectroscopic optical coherence tomography (SOCT) combines the imaging capability of optical coherence tomography with spectroscopic absorption information. SOCT requires a large bandwidth combined with a broadband spectrometer, due to the processing of the measured data, which includes dividing the spectrum in spectral bands. Both, spectral and axial resolution of SOCT depend on the spectral width of each window. A supercontinuum source with its broad spectrum allows a sufficient number of windows combined with a reasonable axial resolution, which depends on the application. Here a SOCT system is used in the visible spectral range from 480 to 730 nm by combining a supercontinuum light source, a Michelson interferometer and a commercial available broadband spectrometer. This wavelength range is chosen because it covers a range of useful absorbers, including that of human proteins. The system is tested with a laser dye rhodamine B for calibration and verification. Rhodamine B has an absorption peak at around 542 nm, which resembles the absorption spectrum of several proteins in the globin group. The results show that the absorption spectrum of rhodamine B can be reconstructed with sufficient accuracy and demonstrate that varying spectroscopic information can be retrieved from different depths.

  6. Single nanoparticle tracking spectroscopic microscope

    DOEpatents

    Yang, Haw; Cang, Hu; Xu, Cangshan; Wong, Chung M.

    2011-07-19

    A system that can maintain and track the position of a single nanoparticle in three dimensions for a prolonged period has been disclosed. The system allows for continuously imaging the particle to observe any interactions it may have. The system also enables the acquisition of real-time sequential spectroscopic information from the particle. The apparatus holds great promise in performing single molecule spectroscopy and imaging on a non-stationary target.

  7. Ni(II)-Schiff base complex as an enzyme inhibitor of hen egg white lysozyme: a crystallographic and spectroscopic study.

    PubMed

    Koley Seth, Banabithi; Ray, Aurkie; Biswas, Sampa; Basu, Samita

    2014-09-01

    The engineering of protein-small molecule interactions becomes imperative today to recognize the essential biochemical processes in living systems. Here we have investigated the interaction between hen egg white lysozyme (HEWL) and a newly synthesized small, simple nickel Schiff base complex (NSC) {(N(1)E,N(2)E)-N(1),N(2)-bis(pyridine-2-ylmethylene)propane-1,2-diaminenickel(II)} using different spectroscopic techniques. We attempted to determine the exact site of the interaction by crystallography. Absorption spectroscopy reveals that the interaction occurs through the ground state. The complex can quench the intrinsic fluorescence of HEWL through a static quenching method. The fluorescence quenching study along with the determination of thermodynamic parameters reveal that NSC binds HEWL spontaneously with moderate binding affinity. The results have also identified that the spontaneity of this enthalpy guided interaction is mainly governed by some H-bonding and hydrophobic interactions which are also indicated by the crystallographic analyses. Moreover, the crystallographic study shows that NSC makes its way into the active site enzyme cavity of HEWL forming a single covalent adduct between Ni(2+) and the oxygen of the active site Asp 52. The possibility of inhibiting the catalytic activity of HEWL by inclusion of NSC in the enzyme active site observed from crystallographic analyses has also been confirmed by enzyme kinetics experiments. PMID:25042037

  8. Dissociative absorption: An empirically unique, clinically relevant, dissociative factor.

    PubMed

    Soffer-Dudek, Nirit; Lassri, Dana; Soffer-Dudek, Nir; Shahar, Golan

    2015-11-01

    Research of dissociative absorption has raised two questions: (a) Is absorption a unique dissociative factor within a three-factor structure, or a part of one general dissociative factor? Even when three factors are found, the specificity of the absorption factor is questionable. (b) Is absorption implicated in psychopathology? Although commonly viewed as "non-clinical" dissociation, absorption was recently hypothesized to be specifically associated with obsessive-compulsive symptoms. To address these questions, we conducted exploratory and confirmatory factor analyses on 679 undergraduates. Analyses supported the three-factor model, and a "purified" absorption scale was extracted from the original inclusive absorption factor. The purified scale predicted several psychopathology scales. As hypothesized, absorption was a stronger predictor of obsessive-compulsive symptoms than of general psychopathology. In addition, absorption was the only dissociative scale that longitudinally predicted obsessive-compulsive symptoms. We conclude that absorption is a unique and clinically relevant dissociative tendency that is particularly meaningful to obsessive-compulsive symptoms. PMID:26241024

  9. Multiple Absorption-line Spectroscopy of the Intergalactic Medium. I. Model

    NASA Astrophysics Data System (ADS)

    Yao, Yangsen; Shull, J. Michael; Danforth, Charles W.; Keeney, Brian A.; Stocke, John T.

    2011-04-01

    We present a physically based absorption-line model for the spectroscopic study of the intergalactic medium (IGM). This model adopts results from Cloudy simulations and theoretical calculations by Gnat & Sternberg to examine the resulting observational signatures of the absorbing gas with the following ionization scenarios: collisional ionization equilibrium (CIE), photoionization equilibrium, hybrid (photo- plus collisional ionization), and non-equilibrium cooling. As a demonstration, we apply this model to new observations made with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope of the IGM absorbers at z ~ 0.1877 along the 1ES 1553+113 sight line. We identify Lyα, C III, O VI, and N V absorption lines with two distinct velocity components (blue at zb = 0.18757; red at zr = 0.18772) separated by Δ(cz)/(1 + z) ≈ 38 km s-1. Joint analyses of these lines indicate that none of the examined ionization scenarios can be applied with confidence to the blue velocity component, although photoionization seems to play a dominant role. For the red component, CIE can be ruled out, but pure photoionization and hybrid scenarios (with T < 1.3 × 105 K) are more acceptable. The constrained ranges of hydrogen density and metallicity of the absorbing gas are n H = (1.9-2.3) × 10-5 cm-3 and Z = (0.43-0.67) Z sun. These constraints indicate O VI and H I ionization fractions, f O VI = 0.10-0.15 and f H I = (3.2-5.1) × 10-5, with total hydrogen column density N H = (0.7-1.2) × 1018 cm-2. This demonstration shows that the joint analysis of multiple absorption lines can constrain the ionization state of an absorber, and results used to estimate the baryonic matter contained in the absorber.

  10. The determination of absorption cross sections and line profiles in vibrational overtone spectra with the use of intracavity absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Bettermann, H.; Kleist, E.; Kok, R.

    1993-03-01

    This contribution presents quantitative absorption data concerning the 7 th CH overtone stretching vibrations of n-hexane and of methylcyclopentane. The transitions are adapted to Lorentzian and Gaussian line shapes. The bank shape analyses yield the spectral positions, absorption cross sections and linewidths of the investigated transitions.

  11. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

    Hua, Duy H. (Inventor); Koo, Sung I. (Inventor); Noh, Sang K. (Inventor)

    2004-01-01

    A class of novel compounds is described for use in affecting lymphatic absorption of cholesterol. Compounds of particular interest are defined by Formula I: ##STR1## or a pharmaceutically acceptable salt thereof.

  12. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  13. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  14. CH_4, C_2H_4, SF_6 and CF_4 Calculated Spectroscopic Databases for the Virtual Atomic and Molecular Data Centre

    NASA Astrophysics Data System (ADS)

    Boudon, Vincent; Wenger, Christian; Surleau, Romain; Louviot, Maud; Faye, Mbaye; Rotger, Maud; Daumont, Ludovic; Bonhommeau, David A.; Tyuterev, Vladimir; Ba, Yaye Awa; Dubernet, Marie-Lise

    2014-06-01

    Two spectroscopic relational databases, denoted MeCaSDa and ECaSDa, have been implemented for methane and ethene, and included in VAMDC (Virtual Atomic and Molecular Data Centre, http://portal.vamdc.eu/vamdc_portal/home.seam) [1]. These databases collect calculated spectroscopic data from the accurate analyses previously performed for the electronic ground state of methane, ethene, and some of their isotopologues: 12CH_4, 13CH_4, and 12C_2H_4 [2]. Both infrared absorption and Raman scattering lines are included. The polyad structures are reported and the transitions are precisely described by their energy, their intensity and the full description of the lower and upper states involved in the transitions. Very recently, we also built on the same model two new databases, named SHeCaSDa and TFMeCaSDa for the SF_6 and CF_4 greenhouse gas molecules, respectively. The relational schemas of these four databases are equivalent and optimized to enable the better compromise between data retrieval and compatibility with the XSAMS (XML Schema for Atoms, Molecules, and Solids) format adopted within the VAMDC European project. [1] Y. A. Ba, Ch. Wenger et al., J. Quant. Spectrosc. Radiat. Transfer, 130, 62 (2013). [2] M.-L. Dubernet, V. Boudon et al., J. Quant. Spectrosc. Radiat. Transfer, 111, 2151 (2010).

  15. CH(4), C(2)H(4), SF(6) and CF(4) Calculated Spectroscopic Databases for the Virtual Atomic and Molecular Data Centre

    NASA Astrophysics Data System (ADS)

    Boudon, V.; Wenger, Ch.; Surleau, R.; Louviot, M.; Faye, M.; Rotger, M.; Daumont, L.; Bonhommeau, D. A.; Tyuterev, Vl. G.; Ba, Y. A.; Dubernet, M.-L.

    2014-06-01

    Two spectroscopic relational databases, denoted MeCaSDa and ECaSDa, have been implemented for methane and ethene, and included in the VAMDC (Virtual Atomic and Molecular Data Centre, http://portal.vamdc.eu/vamdc portal/home.seam)1. These databases collect calculated spectroscopic data from the accurate analyses previously performed for the electronic ground state of methane, ethene, and some of their isotopologues: 12CH4, 13CH4, and 12C2H4 2. Both infrared absorption and Raman scattering lines are included. The polyad structures are reported and the transitions are precisely described by their energy, their intensity, and the full description of the lower and upper states involved in the transitions. Very recently, we also built on the same model two new databases, named SHeCaSDa and TFMeCaSDa for the SF6 and CF4 greenhouse gas molecules, respectively. The relational schemas of these four databases are equivalent and optimized to enable the better compromise between data retrieval and compatibility with the XSAMS (XML Schema for Atoms, Molecules, and Solids) format adopted within the VAMDC European project.

  16. Synthesis, spectroscopic and physicochemical investigations of environmentally benign heterocyclic Schiff base derivatives as antibacterial agents on the bases of in vitro and density functional theory.

    PubMed

    Asiri, Abdullah M; Khan, Salman A; Marwani, Hadi M; Sharma, Kamlesh

    2013-03-01

    A series of Schiff bases were synthesized by the reaction of 4-dimethylamino-benzaldehyde and corresponding active amines under microwave irradiation. Results obtained from spectroscopic (FT-IR, (1)H NMR, (13)C NMR, GC-MS) and elemental analyses of synthesized compounds were in a very good agreement with their chemical structures. UV-Vis and fluorescence spectroscopy measurements provided that all compounds are good absorbent and fluorescent. Fluorescence polarity study demonstrated that these compounds were sensitive to the polarity of the microenvironment provided by different solvents. In addition, spectroscopic and physicochemical parameters, including singlet absorption, extinction coefficient, Stokes shift, oscillator strength and dipole moment, were investigated in order to explore the analytical potential of synthesized compounds. The antibacterial activity of these compounds was first studied in vitro by the disk diffusion assay against two Gram-positive and two Gram-negative bacteria. The minimum inhibitory concentration was then determined with the reference of standard drug tetracycline. The results displayed that compound 1 was better inhibitors of both types of the bacteria (Gram-positive and Gram-negative) than tetracycline. Based on the density functional theory calculations, LUMO and density of compounds (1-5) were calculated to support the antibacterial activities. PMID:23466802

  17. Optical absorption measurement system

    DOEpatents

    Draggoo, Vaughn G.; Morton, Richard G.; Sawicki, Richard H.; Bissinger, Horst D.

    1989-01-01

    The system of the present invention contemplates a non-intrusive method for measuring the temperature rise of optical elements under high laser power optical loading to determine the absorption coefficient. The method comprises irradiating the optical element with a high average power laser beam, viewing the optical element with an infrared camera to determine the temperature across the optical element and calculating the absorption of the optical element from the temperature.

  18. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  19. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  20. Spectroscopic Line Parameters in the Infrared Bands of CH3CN and C2H6

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy

    2010-10-01

    In this paper, measurements of critical spectroscopic line parameters such as positions, absolute intensities and pressure broadened (self- and N2) half-width coefficients for transitions in the ν4 band of CH3CN (acetonitile, ethanenitrile, methyl cyanide) and the ν9 band of C2H6 (ethane) are presented. CH3CN has been measured by remote sensing in the earth's atmosphere, in comets and in interstellar molecular clouds. It is also a constituent in the atmospheres of Titan, Saturn's largest moon. Likewise, C2H6 is also an important constituent in the atmosphere of earth, the giant planets and comets. The 12- μm(˜720-850 cm-1) emission features of this molecule have been observed in spectra from outer solar system bodies of Jupiter, Saturn, Neptune and Titan. Because of their importance in remote sensing measurements, we recently recorded and analyzed a large number of laboratory infrared absorption spectra of pure and N2-broadened spectra of both these molecular bands. Spectra used in these analyses were recorded using either the Bruker IFS 125HR or the Bruker IFS 120HR FTS located at the Pacific Northwest National Laboratory (PNNL), in Richland Washington. To retrieve the various spectral line parameters, a multispectrum nonlinear least squares fitting algorithm was employed and all spectra belonging to each band were fitted simultaneously. Using this fitting technique, the same spectral regions from multiple spectra were fit all at once to maximize the accuracy of the retrieved parameters. The results obtained from present analyses are briefly discussed. In the case of C2H6 both room- and low temperature (˜210-296 K) spectra were recorded, but results from analyzing only room-temperature spectra will be discussed in this work.

  1. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  2. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  3. Identification and Spectroscopic Characterization of Nonheme Iron(III) Hypochlorite Intermediates†

    PubMed Central

    Draksharapu, Apparao; Angelone, Davide; Quesne, Matthew G.; Padamati, Sandeep K.; Gómez, Laura; Hage, Ronald; Costas, Miquel

    2015-01-01

    Abstract FeIII–hypohalite complexes have been implicated in a wide range of important enzyme‐catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post‐translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme FeIII–hypohalite intermediates of possible relevance to iron halogenases. We show that FeIII‐OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo‐ESIMS. DFT methods rationalize the pathways to the formation of the FeIII‐OCl, and ultimately FeIV=O, species and provide indirect evidence for a short‐lived FeII‐OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenases. PMID:27478260

  4. Identification and Spectroscopic Characterization of Nonheme Iron(III) Hypochlorite Intermediates**

    PubMed Central

    Draksharapu, Apparao; Angelone, Davide; Quesne, Matthew G; Padamati, Sandeep K; Gómez, Laura; Hage, Ronald; Costas, Miquel; Browne, Wesley R; de Visser, Sam P

    2015-01-01

    FeIII–hypohalite complexes have been implicated in a wide range of important enzyme-catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post-translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme FeIII–hypohalite intermediates of possible relevance to iron halogenases. We show that FeIII-OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo-ESIMS. DFT methods rationalize the pathways to the formation of the FeIII-OCl, and ultimately FeIV=O, species and provide indirect evidence for a short-lived FeII-OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenases. PMID:25663379

  5. A Combined theoretical and experimental study of conformational and spectroscopic profile of 2-acetamido-5-aminopyridine.

    PubMed

    Pathak, Shilendra K; Srivastava, Ruchi; Sachan, Alok K; Prasad, Onkar; Sinha, Leena

    2015-05-15

    Present work aims at identifying the conformational and spectroscopic profile of 2-acetamido-5-aminopyridine compound by means of experimental and computational methods. To achieve this, three-dimensional potential energy scan (PES) was performed by varying the selected dihedral angles at B3LYP/6-31+G(d,p) level of theory and thus stable conformers of the title compound were determined. The most stable conformer was further optimized at higher level and vibrational wavenumbers were calculated. Experimentally, vibrational features of title compound were determined by FT-IR and FT-Raman spectroscopic methods in the solid phase while the electronic absorption spectrum was recorded in methanol solution. On the basis of these investigations, the conformational and spectroscopic attributes of 2-acetamido-5-aminopyridine were interpreted. PMID:25725210

  6. A Combined theoretical and experimental study of conformational and spectroscopic profile of 2-acetamido-5-aminopyridine

    NASA Astrophysics Data System (ADS)

    Pathak, Shilendra K.; Srivastava, Ruchi; Sachan, Alok K.; Prasad, Onkar; Sinha, Leena

    2015-05-01

    Present work aims at identifying the conformational and spectroscopic profile of 2-acetamido-5-aminopyridine compound by means of experimental and computational methods. To achieve this, three-dimensional potential energy scan (PES) was performed by varying the selected dihedral angles at B3LYP/6-31+G(d,p) level of theory and thus stable conformers of the title compound were determined. The most stable conformer was further optimized at higher level and vibrational wavenumbers were calculated. Experimentally, vibrational features of title compound were determined by FT-IR and FT-Raman spectroscopic methods in the solid phase while the electronic absorption spectrum was recorded in methanol solution. On the basis of these investigations, the conformational and spectroscopic attributes of 2-acetamido-5-aminopyridine were interpreted.

  7. Spectroscopic Methods of Remote Sensing for Vegetation Characterization

    NASA Astrophysics Data System (ADS)

    Kokaly, R. F.

    2013-12-01

    Imaging spectroscopy (IS), often referred to as hyperspectral remote sensing, is one of the latest innovations in a very long history of spectroscopy. Spectroscopic methods have been used for understanding the composition of the world around us, as well as, the solar system and distant parts of the universe. Continuous sampling of the electromagnetic spectrum in narrow bands is what separates IS from previous forms of remote sensing. Terrestrial imaging spectrometers often have hundreds of channels that cover the wavelength range of reflected solar radiation, including the visible, near-infrared (NIR), and shortwave infrared (SWIR) regions. In part due to the large number of channels, a wide variety of methods have been applied to extract information from IS data sets. These can be grouped into several broad classes, including: multi-channel indices, statistical procedures, full spectrum mixing models, and spectroscopic methods. Spectroscopic methods carry on the more than 150 year history of laboratory-based spectroscopy applied to material identification and characterization. Spectroscopic methods of IS relate the positions and shapes of spectral features resolved by airborne and spaceborne sensors to the biochemical and physical composition of vegetation in a pixel. The chlorophyll 680nm, water 980nm, water 1200nm, SWIR 1700nm, SWIR 2100nm, and SWIR 2300nm features have been the subject of study. Spectral feature analysis (SFA) involves isolating such an absorption feature using continuum removal (CR) and calculating descriptors of the feature, such as center position, depth, width, area, and asymmetry. SFA has been applied to quantify pigment and non-pigment biochemical concentrations in leaves, plants, and canopies. Spectral feature comparison (SFC) utilizes CR of features in each pixel's spectrum and linear regression with continuum-removed features in reference spectra in a library of known vegetation types to map vegetation species and communities. SFC has

  8. Spectroscopic Needs for Imaging Dark Energy Experiments

    DOE PAGESBeta

    Newman, Jeffrey A.; Slosar, Anze; Abate, Alexandra; Abdalla, Filipe B.; Allam, Sahar; Allen, Steven W.; Ansari, Reza; Bailey, Stephen; Barkhouse, Wayne A.; Beers, Timothy C.; et al

    2015-03-15

    Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments. Hence, to achieve their full potential, imaging-based experiments will require large setsmore » of objects with spectroscopically-determined redshifts, for two purposes: Training: Objects with known redshift are needed to map out the relationship between object color and z (or, equivalently, to determine empirically-calibrated templates describing the rest-frame spectra of the full range of galaxies, which may be used to predict the color-z relation). The ultimate goal of training is to minimize each moment of the distribution of differences between photometric redshift estimates and the true redshifts of objects, making the relationship between them as tight as possible. The larger and more complete our “training set” of spectroscopic redshifts is, the smaller the RMS photo-z errors should be, increasing the constraining power of imaging experiments; Requirements: Spectroscopic redshift measurements for ~30,000 objects over >~15 widely-separated regions, each at least ~20 arcmin in diameter, and reaching the faintest objects used in a given experiment, will likely be necessary if photometric redshifts are to be trained and calibrated with conventional techniques. Larger, more complete samples (i.e., with longer exposure times) can improve photo-z algorithms and reduce

  9. Spectroscopic Needs for Imaging Dark Energy Experiments

    SciTech Connect

    Newman, Jeffrey A.; Slosar, Anze; Abate, Alexandra; Abdalla, Filipe B.; Allam, Sahar; Allen, Steven W.; Ansari, Reza; Bailey, Stephen; Barkhouse, Wayne A.; Beers, Timothy C.; Blanton, Michael R.; Brodwin, Mark; Brownstein, Joel R.; Brunner, Robert J.; Carrasco-Kind, Matias; Cervantes-Cota, Jorge; Chisari, Nora Elisa; Colless, Matthew; Comparat, Johan; Coupon, Jean; Cheu, Elliott; Cunha, Carlos E.; de la Macorra, Alex; Dell’Antonio, Ian P.; Frye, Brenda L.; Gawiser, Eric J.; Gehrels, Neil; Grady, Kevin; Hagen, Alex; Hall, Patrick B.; Hearin, Andrew P.; Hildebrandt, Hendrik; Hirata, Christopher M.; Ho, Shirley; Honscheid, Klaus; Huterer, Dragan; Ivezic, Zeljko; Kneib, Jean -Paul; Kruk, Jeffrey W.; Lahav, Ofer; Mandelbaum, Rachel; Marshall, Jennifer L.; Matthews, Daniel J.; Menard, Brice; Miquel, Ramon; Moniez, Marc; Moos, H. W.; Moustakas, John; Papovich, Casey; Peacock, John A.; Park, Changbom; Rhodes, Jason; Sadeh, Iftach; Schmidt, Samuel J.; Stern, Daniel K.; Tyson, J. Anthony; von der Linden, Anja; Wechsler, Risa H.; Wood-Vasey, W. M.; Zentner, A.

    2015-03-15

    Ongoing and near-future imaging-based dark energy experiments are critically dependent upon photometric redshifts (a.k.a. photo-z’s): i.e., estimates of the redshifts of objects based only on flux information obtained through broad filters. Higher-quality, lower-scatter photo-z’s will result in smaller random errors on cosmological parameters; while systematic errors in photometric redshift estimates, if not constrained, may dominate all other uncertainties from these experiments. The desired optimization and calibration is dependent upon spectroscopic measurements for secure redshift information; this is the key application of galaxy spectroscopy for imaging-based dark energy experiments. Hence, to achieve their full potential, imaging-based experiments will require large sets of objects with spectroscopically-determined redshifts, for two purposes: Training: Objects with known redshift are needed to map out the relationship between object color and z (or, equivalently, to determine empirically-calibrated templates describing the rest-frame spectra of the full range of galaxies, which may be used to predict the color-z relation). The ultimate goal of training is to minimize each moment of the distribution of differences between photometric redshift estimates and the true redshifts of objects, making the relationship between them as tight as possible. The larger and more complete our “training set” of spectroscopic redshifts is, the smaller the RMS photo-z errors should be, increasing the constraining power of imaging experiments; Requirements: Spectroscopic redshift measurements for ~30,000 objects over >~15 widely-separated regions, each at least ~20 arcmin in diameter, and reaching the faintest objects used in a given experiment, will likely be necessary if photometric redshifts are to be trained and calibrated with conventional techniques. Larger, more complete samples (i.e., with longer exposure times) can improve photo-z algorithms and reduce scatter

  10. Backscatter absorption gas imaging systems and light sources therefore

    DOEpatents

    Kulp, Thomas Jan; Kliner, Dahv A. V.; Sommers, Ricky; Goers, Uta-Barbara; Armstrong, Karla M.

    2006-12-19

    The location of gases that are not visible to the unaided human eye can be determined using tuned light sources that spectroscopically probe the gases and cameras that can provide images corresponding to the absorption of the gases. The present invention is a light source for a backscatter absorption gas imaging (BAGI) system, and a light source incorporating the light source, that can be used to remotely detect and produce images of "invisible" gases. The inventive light source has a light producing element, an optical amplifier, and an optical parametric oscillator to generate wavelength tunable light in the IR. By using a multi-mode light source and an amplifier that operates using 915 nm pump sources, the power consumption of the light source is reduced to a level that can be operated by batteries for long periods of time. In addition, the light source is tunable over the absorption bands of many hydrocarbons, making it useful for detecting hazardous gases.

  11. Atmospheric Measurements by Cavity Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Wu, Tao; Coeur-Tourneur, Cécile; Fertein, Eric; Gao, Xiaoming; Zhao, Weixiong; Zhang, Weijun; Chen, Weidong

    2015-04-01

    Since the last decade, atmospheric environmental monitoring has benefited from the development of novel spectroscopic measurement techniques owing to the significant breakthroughs in photonic technology from the UV to the infrared spectral domain [1]. In this presentation, we will overview our recent development and applications of cavity enhanced absorption spectroscopy techniques for in situ optical monitoring of chemically reactive atmospheric species (such as HONO, NO3, NO2, N2O5) in intensive campaigns [2] and/or in smog chamber studies [3]. These field deployments demonstrated that modern photonic technologies (newly emergent light sources combined with high sensitivity spectroscopic techniques) can provide a useful tool to improve our understanding of tropospheric chemical processes which affect climate, air quality, and the spread of pollution. Experimental detail and preliminary results will be presented. Acknowledgements. The financial support from the French Agence Nationale de la Recherche (ANR) under the NexCILAS (ANR-11-NS09-0002) and the CaPPA (ANR-10-LABX-005) contracts is acknowledged. References [1] X. Cui, C. Lengignon, T. Wu, W. Zhao, G. Wysocki, E. Fertein, C. Coeur, A. Cassez,L. Croisé, W. Chen, et al., "Photonic Sensing of the Atmosphere by absorption spectroscopy", J. Quant. Spectrosc. Rad. Transfer 113 (2012) 1300-1316 [2] T. Wu, Q. Zha, W. Chen, Z. XU, T. Wang, X. He, "Development and deployment of a cavity enhanced UV-LED spectrometer for measurements of atmospheric HONO and NO2 in Hong Kong", Atmos. Environ. 95 (2014) 544-551 [3] T. Wu, C. Coeur-Tourneur, G. Dhont,A. Cassez, E. Fertein, X. He, W. Chen,"Application of IBBCEAS to kinetic study of NO3 radical formation from O3 + NO2 reaction in an atmospheric simulation chamber", J. Quant. Spectrosc. Rad. Transfer 133 (2014)199-205

  12. Petawatt laser absorption bounded

    NASA Astrophysics Data System (ADS)

    Levy, Matthew; Wilks, Scott; Tabak, Max; Libby, Stephen; Baring, Matthew

    2014-10-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top relativistic particle accelerators, ultrafast charged particle imaging systems and fast ignition inertial confinement fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. In this presentation, using a relativistic Rankine-Hugoniot-like analysis, we show how to derive the theoretical maximum and minimum of f. These boundaries constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. Close agreement is shown with several dozens of published experimental data points and simulation results, helping to confirm the theory. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials.

  13. Spectroscopic signature for ferroelectric ice

    NASA Astrophysics Data System (ADS)

    Wójcik, Marek J.; Gług, Maciej; Boczar, Marek; Boda, Łukasz

    2014-09-01

    Various forms of ice exist within our galaxy. Particularly intriguing type of ice - ‘ferroelectric ice' was discovered experimentally and is stable in temperatures below 72 K. This form of ice can generate enormous electric fields and can play an important role in planetary formation. In this letter we present Car-Parrinello simulation of infrared spectra of ferroelectric ice and compare them with spectra of hexagonal ice. Librational region of the spectra can be treated as spectroscopic signature of ice XI and can be of help to identify ferroelectric ice in the Universe.

  14. The far ultraviolet spectroscopic explorer

    NASA Technical Reports Server (NTRS)

    Boggess, A.

    1982-01-01

    The scientific objectives and performance characteristics of a new astronomy mission referred to as the far ultraviolet spectroscopic explorer, or FUSE are being defined by a team involving people experienced instrumental requirements that best meet the scientific needs. The team is intended to have a lifetime of about one year, ending with the submission of a report to NASA which could be used as the basis for an engineering design study. The principal objective of FUSE is to obtain astronomical spectra at wavelengths shorter than is possible with the Space Telescope.

  15. High-energy spectroscopic astrophysics

    NASA Astrophysics Data System (ADS)

    Güdel, Manuel; Walter, Roland

    After three decades of intense research in X-ray and gamma-ray astronomy, the time was ripe to summarize basic knowledge on X-ray and gamma-ray spectroscopy for interested students and researchers ready to become involved in new high-energy missions. This volume exposes both the scientific basics and modern methods of high-energy spectroscopic astrophysics. The emphasis is on physical principles and observing methods rather than a discussion of particular classes of high-energy objects, but many examples and new results are included in the three chapters as well.

  16. Characteristic and spectroscopic properties of the Schiff-base model compounds

    NASA Astrophysics Data System (ADS)

    Jarząbek, B.; Kaczmarczyk, B.; Sęk, D.

    2009-11-01

    Two series of conjugated aromatic imines (Schiff-base model compounds) with different central groups and various side-group substitutions have been synthesized and characterized by elemental analysis, differential scanning calorimetry (DSC) technique, hydrogen nuclear magnetic resonance ( 1H NMR), Fourier transform infrared (FTIR) and ultra-violet and visible light (UV-vis) spectroscopy measurements. The UV-vis absorption of solutions of these compounds in dimethylacetamid (DMA), chloroform and methanol was investigated in the optical range from 240 to 450 nm, where two distinct absorption bands: at 250-280 and 315-360 nm with the different level of absorption have been observed. The influence of compound molecular structure and polarity of solvent on the absorption spectra and the possible optical transitions have been discussed. Structure of diamines in the azomethine models fundamentally affected their spectroscopic properties and conjugation of π-electrons.

  17. First Spectroscopic Identification of Massive Young Stellar Objects in the Galactic Center

    NASA Technical Reports Server (NTRS)

    An, Deokkeun; Ramirez, V.; Sellgren, Kris; Arendt, Richard G.; Boogert, A. C.; Schultheis, Mathias; Stolovy, Susan R.; Cotera, Angela S.; Robitaille, Thomas P.; Smith, Howard A.

    2009-01-01

    We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, reveal gas-phase absorption from CO2 (15.0 microns), C2H2 (13.7 microns) and HCN (14.0 microns). We attribute this absorption to warm, dense gas in massive YSOs. We also detect strong and broad 15 microns CO2 ice absorption features, with a remarkable double-peaked structure. The prominent long-wavelength peak is due to CH3OH-rich ice grains, and is similar to those found in other known massive YSOs. Our IRS observa.tions demonstra.te the youth of these objects, and provide the first spectroscopic identification of massive YSOs in the Galactic Center.

  18. Mapping spectroscopic uncertainties into prospective methane retrieval errors from Sentinel-5 and its precursor

    NASA Astrophysics Data System (ADS)

    Checa-Garcia, R.; Landgraf, J.; Galli, A.; Hase, F.; Velazco, V. A.; Tran, H.; Boudon, V.; Alkemade, F.; Butz, A.

    2015-09-01

    Sentinel-5 (S5) and its precursor (S5P) are future European satellite missions aiming at global monitoring of methane (CH4) column-average dry air mole fractions (XCH4). The spectrometers to be deployed onboard the satellites record spectra of sunlight backscattered from the Earth's surface and atmosphere. In particular, they exploit CH4 absorption in the shortwave infrared spectral range around 1.65 μm (S5 only) and 2.35 μm (both S5 and S5P) wavelength. Given an accuracy goal of better than 2 % for XCH4 to be delivered on regional scales, assessment and reduction of potential sources of systematic error such as spectroscopic uncertainties is crucial. Here, we investigate how spectroscopic errors propagate into retrieval errors on the global scale. To this end, absorption spectra of a ground-based Fourier transform spectrometer (FTS) operating at very high spectral resolution serve as estimate for the quality of the spectroscopic parameters. Feeding the FTS fitting residuals as a perturbation into a global ensemble of simulated S5- and S5P-like spectra at relatively low spectral resolution, XCH4 retrieval errors exceed 0.6 % in large parts of the world and show systematic correlations on regional scales, calling for improved spectroscopic parameters.

  19. The SPHEREx All-Sky Spectroscopic Survey

    NASA Astrophysics Data System (ADS)

    Unwin, Stephen C.; SPHEREx Science Team, SPHEREx Project Team

    2016-06-01

    SPHEREx is a mission to conduct an optical-near-IR survey of the entire sky with a spectrum at every pixel location. It was selected by NASA for a Phase A study in its Small Explorer Program; if selected, development would begin in 2016, and the observatory would start a 2-year prime mission in 2020. An all-sky spectroscopic survey can be used to tackle a wide range of science questions. The SPHEREx science team is focusing on three: (1) Probing the physics of inflation through measuring non-Gaussianity from the study of large-scale structure; (2) Studying the origin of water and biogenic molecules in a wide range of physical and chemical environments via ice absorption spectra; (3) Charting the history of star formation in the universe through intensity mapping of the large-scale spatial power. The instrument is a small wide-field telescope operating in the range of 0.75 - 4.8 µm at a spectral resolution of 41.5 in the optical and 150 at the long-wavelength end. It observes in a sun-sync low-earth orbit, covering the sky like WISE and COBE. SPHEREx is a simple instrument that requires no new technology. The Phase A design has substantial technical and resource margins and can be built with low risk. It is a partnership between Caltech and JPL, with Ball Aerospace and the Korea Astronomy and Space Science Institute as major partners. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. © 2016 California Institute of Technology. Government sponsorship acknowledged.

  20. Percutaneous absorption from soil.

    PubMed

    Andersen, Rosa Marie; Coman, Garrett; Blickenstaff, Nicholas R; Maibach, Howard I

    2014-01-01

    Abstract Some natural sites, as a result of contaminants emitted into the air and subsequently deposited in soil or accidental industrial release, have high levels of organic and non-organic chemicals in soil. In occupational and recreation settings, these could be potential sources of percutaneous exposure to humans. When investigating percutaneous absorption from soil - in vitro or vivo - soil load, particle size, layering, soil "age" time, along with the methods of performing the experiment and analyzing the results must be taken into consideration. Skin absorption from soil is generally reduced compared with uptake from water/acetone. However, the absorption of some compounds, e.g., pentachlorophenol, chlorodane and PCB 1254, are similar. Lipophilic compounds like dichlorodiphenyltrichloroethane, benzo[A]pyrene, and metals have the tendency to form reservoirs in skin. Thus, one should take caution in interpreting results directly from in vitro studies for risk assessment; in vivo validations are often required for the most relevant risk assessment. PMID:25205703

  1. Towards quantitative atmospheric water vapor profiling with differential absorption lidar.

    PubMed

    Dinovitser, Alex; Gunn, Lachlan J; Abbott, Derek

    2015-08-24

    Differential Absorption Lidar (DIAL) is a powerful laser-based technique for trace gas profiling of the atmosphere. However, this technique is still under active development requiring precise and accurate wavelength stabilization, as well as accurate spectroscopic parameters of the specific resonance line and the effective absorption cross-section of the system. In this paper we describe a novel master laser system that extends our previous work for robust stabilization to virtually any number of multiple side-line laser wavelengths for the future probing to greater altitudes. In this paper, we also highlight the significance of laser spectral purity on DIAL accuracy, and illustrate a simple re-arrangement of a system for measuring effective absorption cross-section. We present a calibration technique where the laser light is guided to an absorption cell with 33 m path length, and a quantitative number density measurement is then used to obtain the effective absorption cross-section. The same absorption cell is then used for on-line laser stabilization, while microwave beat-frequencies are used to stabilize any number of off-line lasers. We present preliminary results using ∼300 nJ, 1 μs pulses at 3 kHz, with the seed laser operating as a nanojoule transmitter at 822.922 nm, and a receiver consisting of a photomultiplier tube (PMT) coupled to a 356 mm mirror. PMID:26368258

  2. The low-ion QSO absorption-line systems

    SciTech Connect

    Lanzetta, K.M.

    1988-01-01

    Various techniques are used to investigate the class of QSO absorption-line systems that exhibit low-ion absorption lines. Four separate investigations are conducted as follows: Spectroscopy of 32 QSOs at red wavelengths is presented and used to investigate intermediate-redshift MgII absorption. A total of 22 Mg II doublets are detected, from which properties of the Mg II absorbers are derived. Marginal evidence for intrinsic evolution of the number density of the Mg II absorbers with redshift is found. The data are combined with previous observations of C IV and C II seen in the same QSOs at blue wavelengths, and the properties of Mg II- and C IV-selected systems are compared. A sample is constructed of 129 QSOs for which are available published data suitable for detecting absorption-line systems that are optically thick to Lyman continuum radiation. A total of 53 such Lyman-limit systems are found, from which properties of the Lyman-limit systems are derived. It is found that the rate of incidence of the systems does not strongly evolved with redshift. This result is contrasted with the evolution found previously for systems selected on the basis of Mg II absorption. Spectroscopy at red wavelengths of eight QSOs with known damped Ly{alpha} absorption systems is presented. Spectroscopic and spectrophotometric observations aimed at detecting molecular hydrogen and dust in the z = 2.796 damped Ly{alpha} absorber toward Q1337 + 113 are presented.

  3. Fourier transform infrared spectroscopic study of intact cells of the nitrogen-fixing bacterium Azospirillum brasilense

    NASA Astrophysics Data System (ADS)

    Kamnev, A. A.; Ristić, M.; Antonyuk, L. P.; Chernyshev, A. V.; Ignatov, V. V.

    1997-06-01

    The data of Fourier transform infrared (FTIR) spectroscopic measurements performed on intact cells of the soil nitrogen-fixing bacterium Azospirillum brasilense grown in a standard medium and under the conditions of an increased metal uptake are compared and discussed. The structural FTIR information obtained is considered together with atomic absorption spectrometry (AAS) data on the content of metal cations in the bacterial cells. Some methodological aspects concerning preparation of bacterial cell samples for FTIR measurements are also discussed.

  4. Spectroscopic studies on the interaction of cysteine capped CuS nanoparticles with tyrosine

    SciTech Connect

    Prasanth, S.; Raj, D. Rithesh; Kumar, T. V. Vineesh; Sudarsanakumar, C.

    2015-06-24

    Biocompatible cysteine coated CuS nanoparticles were synthesized by a simple aqueous solution method. Hexagonal phase of the samples were confirmed from X-ray diffraction and particle size found to be 9 nm. The possible interaction between the bioactive cysteine capped CuS nanoparticles and tyrosine were investigated using spectroscopic techniques such as UV-Visible absorption and fluorescence spectroscopy. It is observed that the luminescence intensity of tyrosine molecule enhanced by the addition CuS nanoparticles.

  5. Spectroscopic studies on the interaction of cysteine capped CuS nanoparticles with tyrosine

    NASA Astrophysics Data System (ADS)

    Prasanth, S.; Raj, D. Rithesh; Kumar, T. V. Vineesh; Sudarsanakumar, C.

    2015-06-01

    Biocompatible cysteine coated CuS nanoparticles were synthesized by a simple aqueous solution method. Hexagonal phase of the samples were confirmed from X-ray diffraction and particle size found to be 9 nm. The possible interaction between the bioactive cysteine capped CuS nanoparticles and tyrosine were investigated using spectroscopic techniques such as UV-Visible absorption and fluorescence spectroscopy. It is observed that the luminescence intensity of tyrosine molecule enhanced by the addition CuS nanoparticles.

  6. Plasmon-resonant microchip emitters and detectors for terahertz sensing and spectroscopic applications

    NASA Astrophysics Data System (ADS)

    Otsuji, Taiichi; Komori, Tsuneyoshi; Watanabe, Takayuki; Suemitsu, Tetsuya; Coquillat, Dominique; Knap, Wojciech

    2010-04-01

    This paper reviews recent advances in emission and detection of terahertz (THz) radiation utilizing two-dimensional plasmons in semiconductor heterostructures and their possible sensing and spectroscopic applications. The device is introduced as a light source into a Fourier-transform THz spectrometer. Water-vapor absorption lines as well as fingerprints of honey and maple syrup of sugar-group materials were successfully observed. Absolute sensitivity characteristics and detection polarization are also presented, showing the possibility of new highly efficient THz detectors.

  7. Spectroscopic characterizations of organic/inorganic nanocomposites

    NASA Astrophysics Data System (ADS)

    Govani, Jayesh R.

    2009-12-01

    In the present study, pure and 0.3 wt%, 0.4 wt%, as well as 0.5 wt% L-arginine doped potassium dihydrogen phosphate (KDP) crystals were grown using solution growth techniques and further subjected to infrared (IR) absorption and Raman studies for confirmation of chemical group functionalization for investigating the incorporation mechanism of the L-arginine organic material into the KDP crystal structure. Infrared spectroscopic analysis suggests that structural changes are occurring for the L-arginine molecule as a result of its interaction with the KPD crystal. Infrared spectroscopic technique confirms the disturbance of the N-H, C-H and C-N bonds of the amino acid, suggesting successful incorporation of L-arginine into the KDP crystals. Raman analysis also reveals modification of the N-H, C-H and C-N bonds of the amino acid, implying successful inclusion of L-arginine into the KDP crystals. With the help of Gaussian software, a prediction of possible incorporation mechanisms of the organic material was obtained from comparison of the simulated infrared and Raman vibrational spectra with the experimental results. Furthermore, we also studied the effect of L-arginine doping on the thermal stability of the grown KDP crystal by employing Thermo gravimetric analysis (TGA). TGA suggests that increasing the level of L-arginine doping speeds the decomposition process and it weakens the KDP crystal, which indicates successful doping of the KDP crystals with L-arginine amino acid. Urinary stones are one of the oldest and most widely spread diseases in humans, animals and birds. Many remedies have been employed through the ages for the treatment of urinary stones. Recent medicinal measures reflect the modern advances, which are based on surgical removal, percutaneous techniques and extracorporeal shock wave lithotripsy (ESWL). Although these procedures are valuable, they are quite expensive for most people. Furthermore, recurrence of these diseases is awfully frequent with

  8. Multiplasmon Absorption in Graphene

    NASA Astrophysics Data System (ADS)

    Jablan, Marinko; Chang, Darrick E.

    2015-06-01

    We show that graphene possesses a strong nonlinear optical response in the form of multiplasmon absorption, with exciting implications in classical and quantum nonlinear optics. Specifically, we predict that graphene nanoribbons can be used as saturable absorbers with low saturation intensity in the far-infrared and terahertz spectrum. Moreover, we predict that two-plasmon absorption and extreme localization of plasmon fields in graphene nanodisks can lead to a plasmon blockade effect, in which a single quantized plasmon strongly suppresses the possibility of exciting a second plasmon.

  9. Chaotic Systems with Absorption

    NASA Astrophysics Data System (ADS)

    Altmann, Eduardo G.; Portela, Jefferson S. E.; Tél, Tamás

    2013-10-01

    Motivated by applications in optics and acoustics we develop a dynamical-system approach to describe absorption in chaotic systems. We introduce an operator formalism from which we obtain (i) a general formula for the escape rate κ in terms of the natural conditionally invariant measure of the system, (ii) an increased multifractality when compared to the spectrum of dimensions Dq obtained without taking absorption and return times into account, and (iii) a generalization of the Kantz-Grassberger formula that expresses D1 in terms of κ, the positive Lyapunov exponent, the average return time, and a new quantity, the reflection rate. Simulations in the cardioid billiard confirm these results.

  10. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  11. Inclusion complexation between baicalein and β-cyclodextrin and the influence of β-cyclodextrin on the binding of baicalein with DNA: a spectroscopic approach.

    PubMed

    Sameena, Yousuf; Chandrasekaran, Sowrirajan; Israel V M V, Enoch

    2016-07-01

    This work deals with the commonly studied cyclic oligosaccharide and gains importance as it is entered on a drug delivering carbohydrate and provides insight into the oligosaccharide complex-biomolecular interaction. The binding of a flavone, baicalein, to β-cyclodextrin and calf thymus DNA is studied. The binding of baicalein to calf thymus DNA in the presence of β-cyclodextrin is analysed using the UV-vis absorption and fluorescence spectroscopy. The mode of binding and structure of the baicalein-β-cyclodextrin complex are reported. The role of the structure and the stoichiometry of the inclusion complex of baicalein-β-cyclodextrin in its influence on DNA binding are analysed. Highlights • This paper deals with the binding of a flavone, baicalein to β-cyclodextrin and/or DNA. • The inclusion complexation between baicalein and β-cyclodextrin is analysed. • The stoichiometry and the binding strength of the inclusion complex is reported. • The role of β-cyclodextrin in tuning the binding of baicalein to DNA is emphasized. • Spectroscopic and docking analysis are used to articulate the results. PMID:26308145

  12. Spectroscopic observations and analysis of the peculiar SN1999aa

    SciTech Connect

    Garavini, G.; Folatelli, G.; Goobar, A.; Nobili, S.; Aldering,G.; Amadon, A.; Amanullah, R.; Astier, P.; Balland, C.; Blanc, G.; Burns,M.S.; Conley, A.; Dahlen, T.; Deustua, S.E.; Ellis, R.; Fabbro, S.; Fan,X.; Frye, B.; Gates, E.L.; Gibbons, R.; Goldhaber, G.; Goldman, B.; Groom, D.E.; Haissinski, J.; Hardin, D.; Hook, I.M.; Howell, D.A.; Kasen,D.; Kent, S.; Kim, A.G.; Knop, R.A.; Lee, B.C.; Lidman, C.; Mendez, J.; Miller, G.J.; Moniez, M.; Mourao, A.; Newberg, H.; Nugent, P.E.; Pain,R.; Perdereau, O.; Perlmutter, S.; Prasad, V.; Quimby, R.; Raux, J.; Regnault, N.; Rich, J.; Richards, G.T.; Ruiz-Lapuente, P.; Sainton, G.; Schaefer, B.E.; Schahmaneche, K.; Smith, E.; Spadafora, A.L.; Stanishev,V.; Walton, N.A.; Wang, L.; Wood-Vasey, W.M.

    2003-12-10

    We present an extensive new time series of spectroscopic data of the peculiar SN 1999aa in NGC 2595. Our data set includes 25 optical spectra between -11 and +58 days with respect to B-band maximum light, providing an unusually complete time history. The early spectra resemble those of an SN 1991T-like object but with a relatively strong CaH and K absorption feature. The first clear sign of Si II lambda 6355, characteristic of Type Ia supernovae, is found at day -7, and its velocity remains constant up to at least the first month after B-band maximum light. The transition to normal-looking spectra is found to occur earlier than in SN 1991T, suggesting SN 1999aa as a possible link between SN 1991T-like and Branch-normal supernovae. Comparing the observations with synthetic spectra, doubly ionized Fe, Si, and Ni are identified at early epochs. These are characteristic of SN 1991 T-like objects. Furthermore, in the day -11 spectrum, evidence is found for an absorption feature that could be identified as high velocity C II lambda 6580 or H alpha. At the same epoch C III lambda 4648.8 at photospheric velocity is probably responsible for the absorption feature at 4500 8. High-velocity Ca is found around maximum light together with Si II and Fe II confined in a narrow velocity window. Implied constraints on supernovae progenitor systems and explosion hydrodynamic models are briefly discussed.

  13. Spectroscopic imaging in electron microscopy

    SciTech Connect

    Pennycook, Stephen J; Colliex, C.

    2012-01-01

    In the scanning transmission electron microscope, multiple signals can be simultaneously collected, including the transmitted and scattered electron signals (bright field and annular dark field or Z-contrast images), along with spectroscopic signals such as inelastically scattered electrons and emitted photons. In the last few years, the successful development of aberration correctors for the electron microscope has transformed the field of electron microscopy, opening up new possibilities for correlating structure to functionality. Aberration correction not only allows for enhanced structural resolution with incident probes into the sub-angstrom range, but can also provide greater probe currents to facilitate mapping of intrinsically weak spectroscopic signals at the nanoscale or even the atomic level. In this issue of MRS Bulletin, we illustrate the power of the new generation of electron microscopes with a combination of imaging and spectroscopy. We show the mapping of elemental distributions at atomic resolution and also the mapping of electronic and optical properties at unprecedented spatial resolution, with applications ranging from graphene to plasmonic nanostructures, and oxide interfaces to biology.

  14. Diode laser absorption sensors for combustion control

    NASA Astrophysics Data System (ADS)

    Xin, Zhou

    Combustion is the most widely used energy conversion technique in the world. Diode-laser absorption sensors offer significant opportunities and advantages for in situ measurements of multiple combustion parameters such as temperature and species concentration due to their high sensitivity, high spectral resolution, fast time response, robustness and non-intrusive character. The overall objective of this thesis is to design and develop time-resolved and real-time tunable diode laser sensors with the potential for combustion control. A crucial element in the design of a tunable-diode-laser optical-absorption-based sensor is the selection of optimum transitions. The strategy and spectroscopic criteria for selecting optimum wavelength regions and absorption line combinations are developed. The development of this design-rule approach establishes a new paradigm to optimize tunable diode laser sensors for target applications. The water vapor spectrum in the 1-2 mum near-infrared region is systematically analyzed to find the best absorption transition pairs for sensitive measurement of temperature in the target combustion environment using a single tunable diode laser. Two sensors are developed in this work. The first sensor is a 1.8 mum, single-laser temperature sensor based on direct absorption scans. Successful time-resolved measurements in a variety of laboratory and practical devices are presented and used to identify potential improvements, and design rules for a second-generation sensor are developed based on the lessons learned. The second generation sensor is a 1.4 mum, single-laser temperature sensor using water vapor absorption detected by wavelength-modulation spectroscopy (WMS), which facilitates rapid data analysis and a 2 kHz real-time data rate in the combustion experiments reported here. Demonstration experiments in a heated cell and a forced Hencken burner confirm the sensitivity and accuracy of the sensors. The first application of TDL thermometry to a

  15. Spectroscopic Survey Of Delta Scuti Stars

    NASA Astrophysics Data System (ADS)

    Kahraman Alicavus, Filiz; Niemczura, Ewa; Polinska, Magdalena; Helminiak, Krzysztof G.; Lampens, Patricia; Molenda-Zakowicz, Joanna; Ukita, Nobuharu; Kambe, Eiji

    2016-07-01

    We present the results of a spectroscopic study of pulsating stars of Delta Scuti type. The spectral types and luminosity classes, fundamental atmospheric parameters (the effective temperature, surface gravity, microturbulent velocity), detailed chemical composition and projected rotational velocities of a significant number of Delta Scuti-type stars were derived. The spectral classification was performed by comparing the spectra of our targets with the spectra of standard stars. The atmospheric parameters were determined by using different methods. The initial atmospheric parameters were derived from the analysis of photometric indices, the spectral energy distribution and the hydrogen lines, while the final atmospheric parameters were obtained from the analysis of iron lines. The spectrum synthesis method was used to determine chemical compositions of the investigated stars. As a result, we derived accurate atmospheric parameters, the projected rotational velocities and the abundance patterns of analysed sample. These results allow us to examine the position of Delta Scuti-type stars in the H-R diagram, and to investigate the effect of the rotational velocity on pulsation properties and a chemical difference between the Delta Scuti-type stars and the Gamma Doradus and A-F type hybrid stars.

  16. HEXA: a machine for spectroscopic cartography

    NASA Astrophysics Data System (ADS)

    Barrado, D.; Aceituno, J.; Galadí, D.; Iglesias-Páramo, J.; Sánchez, S. F.

    2013-05-01

    We have performed a conceptual and viability study for HEXA, a 6.5 m aperture, wide-field telescope, with high multiplexing factor, framed in the strategic plan for the Calar Alto observatory in 2014-2018 and beyond, centred on the scientific cases arisen from the current need for wide-field spectroscopic surveys with very large multiplexing capability. The baseline design considers a field-of-view of 1.5°, multiplexing factor around or over 500 and possible spectral resolutions in the interval R = 5000 - 50 000, with instruments placed on two Nasmyth platforms. Other variants are also considered, including Ritchey-Chrétien and prime-focus solutions. The telescope concept is described, together with the instruments that have already undergone, or that are still undergoing, the conceptual design process: CEO, an innovative Imaging Fourier Transform spectrograph. GEA, a Gaia-inspired drift-scanning slitless spectrograph. BRONTESS, a fast and simple camera for guiding and ToO work. A PMAS-based multi-IFU, highly multiplexed spectrograph. And the multi-fibre spectrograph GYGES. Some of the instrument concepts analysed are based on the versatile fiber-positioner HECATE (with a minimum of 361 positioners). Some of the fibre-based instruments would allow, too, fibres entering a battery of CAF{É}-type high-res spectrographs.

  17. Direct UV-spectroscopic measurement of selected ionic-liquid vapors

    SciTech Connect

    Dai, Sheng; Luo, Huimin; Wang, Congmin; Li, Haoran

    2010-01-01

    The hallmark of ionic liquids lies in their negligible vapor pressure. This ultralow vapor pressure makes it difficult to conduct the direct spectroscopic measurement of ionic-liquid vapors. In fact, there have been no electronic spectroscopic data currently available for ionic-liquid vapors. This deficiency significantly hampers the fundamental understanding of the unique molecular structures of ionic liquids. Herein, the UV absorption spectra of eight ionic liquids, such as 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Bmim{sup +}] [Tf{sub 2}N{sup -}]) and 1-ethyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide ([Emim{sup +}][beti{sup -}]) in the vapor phase in a distillation-like environment, were measured through a high-temperature spectroscopic technique to fill this knowledge gap. Two strong absorption peaks of the [Bmim{sup +}][Tf{sub 2}N{sup -}] vapor lie at 202 and 211 nm, slightly different from those of the neat [Bmim{sup +}][Tf{sub 2}N{sup -}] thin film and its solution in water. Based on the quantitative determination of the vapor absorption spectra as a function of temperature, the vaporization enthalpies of these ionic liquids vapors were measured and found to be in good agreement with the corresponding literature values. This in situ method opens up a new avenue to study the nature of ionic-liquid vapors and to determine the vaporization enthalpies of ionic liquids.

  18. Covalent dyads of porphyrin-fullerene and perylene-fullerene for organic photovoltaics: Spectroscopic and photocurrent studies

    NASA Astrophysics Data System (ADS)

    Wróbel, Danuta; Lewandowska, Kornelia

    2011-07-01

    Supermolecular complexes of zinc porphyrin or perylenediimide as covalent dyads with fullerene (C 60) in chloroform and as Langmuir-Blodgett layers on an Au substrate were studied. In our studies we have used following spectroscopic methods: electronic absorption, fluorescence and electron spin resonance in solution. Also infrared absorption spectra in a KBr pellet and reflectance-absorption in Langmuir-Blodgett layers were monitored. Photocurrent generation in a photoelectrochemical cell was also studied. The redistribution of charge both upon porphyrin linkage to C 60 and when the systems are deposited on the Au substrate was shown. Photocurrent examinations show a great influence of the fullerene presence on photoresponse of the systems.

  19. Methodical study on plaque characterization using integrated vascular ultrasound, strain and spectroscopic photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Graf, Iulia M.; Su, Jimmy; Yeager, Doug; Amirian, James; Smalling, Richard; Emelianov, Stanislav

    2011-03-01

    Carotid atherosclerosis has been identified as a potential risk factor for cerebrovascular events, but information about its direct effect on the risk of recurrent stroke is limited due to incomplete diagnosis. The combination of vascular ultrasound, strain rate and spectroscopic photoacoustics could improve the timely diagnosis of plaque status and risk of rupturing. Current ultrasound techniques can noninvasively image the anatomy of carotid arteries. The spatio-temporal variation in displacement of different regions within the arterial wall can be derived from ultrasound radio frequency data; therefore an ultrasound based strain rate imaging modality can be used to reveal changes in arterial mechanical properties. Additionally, spectroscopic photoacoustic imaging can provide information on the optical absorption properties of arterial tissue and it can be used to identify the location of specific tissue components, such as lipid pools. An imaging technique combining ultrasound, strain rate and spectroscopic photoacoustics was tested on an excised atherosclerotic rabbit aorta. The ultrasound image illustrates inhomogeneities in arterial wall thickness, the strain rate indicates the arterial segment with reduced elasticity and the spectroscopic photoacoustic image illustrates the accumulation of lipids. The results demonstrated that ultrasound, strain rate and spectroscopic photoacoustic imaging are complementary. Thus the integration of the three imaging modalities advances the characterization of atherosclerotic plaques.

  20. Spectroscopic and quantum chemical studies on bromopyrazone

    NASA Astrophysics Data System (ADS)

    Gökce, Halil; Bahçeli, Semiha

    2014-12-01

    In this study, the FT-IR, micro-Raman and UV-vis. spectra of bromopyrazone molecule, C10H8BrN3O, (with synonym,1-phenyl-4-amino-5-bromopyridazon-(6) or 5-amino-4-bromo-2-phenyl-3(2H)-pyridazinone) were recorded experimentally. The molecular structure, vibrational wavenumbers, electronic transition absorption wavelengths in ethanol solvent, HOMOs and LUMOs analyses, molecular electrostatic potential (MEP), natural bond orbitals (NBO), nonlinear optical (NLO) properties and atomic charges of bromopyrazone molecule have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. The obtained results show that the calculated vibrational frequencies and UV-vis. values are in a good agreement with experimental data.

  1. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

    A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

  2. Total absorption Cherenkov spectrometers

    NASA Astrophysics Data System (ADS)

    Malinovski, E. I.

    2015-05-01

    A short review of 50 years of work done with Cherenkov detectors in laboratories at the Lebedev Physical Institute is presented. The report considers some issues concerning the use of Cherenkov total absorption counters based on lead glass and heavy crystals in accelerator experiments.

  3. Cholesterol Absorption and Metabolism.

    PubMed

    Howles, Philip N

    2016-01-01

    Inhibitors of cholesterol absorption have been sought for decades as a means to treat and prevent cardiovascular diseases (CVDs) associated with hypercholesterolemia. Ezetimibe is the one clear success story in this regard, and other compounds with similar efficacy continue to be sought. In the last decade, the laboratory mouse, with all its genetic power, has become the premier experimental model for discovering the mechanisms underlying cholesterol absorption and has become a critical tool for preclinical testing of potential pharmaceutical entities. This chapter briefly reviews the history of cholesterol absorption research and the various gene candidates that have come under consideration as drug targets. The most common and versatile method of measuring cholesterol absorption is described in detail along with important considerations when interpreting results, and an alternative method is also presented. In recent years, reverse cholesterol transport (RCT) has become an area of intense new interest for drug discovery since this process is now considered another key to reducing CVD risk. The ultimate measure of RCT is sterol excretion and a detailed description is given for measuring neutral and acidic fecal sterols and interpreting the results. PMID:27150091

  4. Lipids: Absorption and transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to the hydrophobic nature of lipids, dietary fat is handled differently than protein or carbohydrate with respect with digestion and absorption. Dietary fats are broken down throughout the gastrointestinal system. A unique group of enzymes and cofactors allows this process to proceed in an eff...

  5. ZINC ABSORPTION BY INFANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Zinc is a vital mineral in human nutrition, and rare cases of overt zinc deficiency are well described in term and preterm infants. A variety of methods have been developed to assess zinc absorption, retention, and balance in humans, either using mass (metabolic) balance or stable isotope-based METH...

  6. Absorption driven focus shift

    NASA Astrophysics Data System (ADS)

    Harrop, N.; Wolf, S.; Maerten, O.; Dudek, K.; Ballach, S.; Kramer, R.

    2016-03-01

    Modern high brilliance near infrared lasers have seen a tremendous growth in applications throughout the world. Increased productivity has been achieved by higher laser power and increased brilliance of lasers. Positive impacts on the performance and costs of parts are opposed to threats on process stability and quality, namely shift of focus position over time. A high initial process quality will be reduced by contamination of optics, eventually leading to a focus shift or even destruction of the optics. Focus analysis at full power of multi-kilowatt high brilliance lasers is a very demanding task because of high power densities in the spot and the high power load on optical elements. With the newly developed high power projection optics, the High-Power Micro-Spot Monitor High Brilliance (HP-MSM-HB) is able to measure focus diameter as low as 20 μm at power levels up to 10 kW at very low internal focus shift. A main driving factor behind thermally induced focus shift is the absorption level of the optical element. A newly developed measuring system is designed to determine the relative absorption level in reference to a gold standard. Test results presented show a direct correlation between absorption levels and focus shift. The ability to determine the absorption level of optical elements as well as their performance at full processing power before they are put to use, enables a high level of quality assurance for optics manufacturers and processing head manufacturers alike.

  7. Raman spectroscopic characterisations and analytical discrimination between caffeine and demethylated analogues of pharmaceutical relevance

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Munshi, T.; Anstis, M.

    2005-05-01

    The FT Raman spectrum of caffeine was analysed along with that of its demethylated analogues, theobromine and theophylline. The similar but not identical structures of these three compounds allowed a more detailed assignment of the Raman bands. Noticeable differences in the Raman spectra of these compounds were apparent and key marker bands have been identified for the spectroscopic identification of these three compounds.

  8. QUANTIFYING THE BIASES OF SPECTROSCOPICALLY SELECTED GRAVITATIONAL LENSES

    SciTech Connect

    Arneson, Ryan A.; Brownstein, Joel R.; Bolton, Adam S. E-mail: joelbrownstein@astro.utah.edu

    2012-07-01

    Spectroscopic selection has been the most productive technique for the selection of galaxy-scale strong gravitational lens systems with known redshifts. Statistically significant samples of strong lenses provide a powerful method for measuring the mass-density parameters of the lensing population, but results can only be generalized to the parent population if the lensing selection biases are sufficiently understood. We perform controlled Monte Carlo simulations of spectroscopic lens surveys in order to quantify the bias of lenses relative to parent galaxies in velocity dispersion, mass axis ratio, and mass-density profile. For parameters typical of the SLACS and BELLS surveys, we find (1) no significant mass axis ratio detection bias of lenses relative to parent galaxies; (2) a very small detection bias toward shallow mass-density profiles, which is likely negligible compared to other sources of uncertainty in this parameter; (3) a detection bias toward smaller Einstein radius for systems drawn from parent populations with group- and cluster-scale lensing masses; and (4) a lens-modeling bias toward larger velocity dispersions for systems drawn from parent samples with sub-arcsecond mean Einstein radii. This last finding indicates that the incorporation of velocity-dispersion upper limits of non-lenses is an important ingredient for unbiased analyses of spectroscopically selected lens samples. In general, we find that the completeness of spectroscopic lens surveys in the plane of Einstein radius and mass-density profile power-law index is quite uniform, up to a sharp drop in the region of large Einstein radius and steep mass-density profile, and hence that such surveys are ideally suited to the study of massive field galaxies.

  9. The Origin, Composition and History of Comets from Spectroscopic Studies

    NASA Astrophysics Data System (ADS)

    Allamandola, L. J.

    1997-12-01

    A wealth of information essential to understanding the composition and physical structure of cometary ice and hence gain deep insight into the comet's origin and history, can be gleaned by carrying out a full range of spectroscopic studies on the returned sample. These studies ought to be among the first performed as they are generally non-destructive and will provide a broad data bank which will be crucial in planning subsequent analysis. Examples of the spectroscopic techniques along with relative sensitivities and transitions probed, are discussed. Different kind of "spectroscopy" is summarized, with emphasis placed on the kind of information each provides. Infrared spectroscopy should be the premier method of analysis as the mid-IR absorption spectrum of a substance contains more global information about the identity and structure of that material than any other property. In fact, the greatest strides in our understanding of the composition of interstellar ices (thought by many to be the primordial material from which comets have formed) have been taken during the past ten years or so because this was when high quality infrared spectra of the interstellar medium (ISM) first became available. The interpretation of the infrared spectra of mixtures, such as expected in comets, is often (not always) ambiguous. Consequently, a full range of other non-destructive, complementary spectroscopic measurements are required to fully characterize the material, to probe for substances for which the IR is not well suited and to lay the groundwork for future analysis. Given the likelihood that the icy component (including some of the organic and mineral phases) of the returned sample will be exceedingly complex, these techniques must be intensely developed over the next decade and then made ready to apply flawlessly to what will certainly be one of the most precious, and most challenging, samples ever analyzed.

  10. The Origin, Composition and History of Comets from Spectroscopic Studies

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1997-01-01

    A wealth of information essential to understanding the composition and physical structure of cometary ice and hence gain deep insight into the comet's origin and history, can be gleaned by carrying out a full range of spectroscopic studies on the returned sample. These studies ought to be among the first performed as they are generally non-destructive and will provide a broad data bank which will be crucial in planning subsequent analysis. Examples of the spectroscopic techniques along with relative sensitivities and transitions probed, are discussed. Different kind of "spectroscopy" is summarized, with emphasis placed on the kind of information each provides. Infrared spectroscopy should be the premier method of analysis as the mid-IR absorption spectrum of a substance contains more global information about the identity and structure of that material than any other property. In fact, the greatest strides in our understanding of the composition of interstellar ices (thought by many to be the primordial material from which comets have formed) have been taken during the past ten years or so because this was when high quality infrared spectra of the interstellar medium (ISM) first became available. The interpretation of the infrared spectra of mixtures, such as expected in comets, is often (not always) ambiguous. Consequently, a full range of other non-destructive, complementary spectroscopic measurements are required to fully characterize the material, to probe for substances for which the IR is not well suited and to lay the groundwork for future analysis. Given the likelihood that the icy component (including some of the organic and mineral phases) of the returned sample will be exceedingly complex, these techniques must be intensely developed over the next decade and then made ready to apply flawlessly to what will certainly be one of the most precious, and most challenging, samples ever analyzed.

  11. The Hubble Spectroscopic Legacy Archive

    NASA Astrophysics Data System (ADS)

    Peeples, Molly S.; Tumlinson, Jason; Fox, Andrew; Aloisi, Alessandra; Ayres, Thomas R.; Danforth, Charles; Fleming, Scott W.; Jenkins, Edward B.; Jedrzejewski, Robert I.; Keeney, Brian A.; Oliveira, Cristina M.

    2016-01-01

    With no future space ultraviolet instruments currently planned, the data from the UV spectrographs aboard the Hubble Space Telescope have a legacy value beyond their initial science goals. The Hubble Spectroscopic Legacy Archive will provide to the community new science-grade combined spectra for all publicly available data obtained by the Cosmic Origins Spectrograph (COS) and the Space Telescope Imaging Spectrograph (STIS). These data will be packaged into "smart archives" according to target type and scientific themes to facilitate the construction of archival samples for common science uses. A new "quick look" capability will make the data easy for users to quickly access, assess the quality of, and download for archival science starting in Cycle 24, with the first generation of these products for the FUV modes of COS available online via MAST in early 2016.

  12. Spectroscopic analysis of vermicompost for determination of nutritional quality.

    PubMed

    Subhash Kumar, M; Rajiv, P; Rajeshwari, Sivaraj; Venckatesh, Rajendran

    2015-01-25

    Spectroscopic analysis has been carried out to examine the compost quality, maturity and nutritional levels of vermicompost and compost of Eichhornia. 50% Eichhorniacrassipes and 50% cow dung mixtures were vermicomposted using earthworms (Eudrilus eugeniae) and collected on different days' time intervals. Fourier transform infrared spectroscopy (FT-IR) spectra reveal the presence of humic substance from compost and vermicompost, which improves the soil fertility. Gas chromatography-mass spectroscopy (GC-MS) analysis shows maximum level of Benzene propanoic acid (95.98%) and by 2-Propanone, 1-Phenyl-, OXIM (10.10%) from vermicompost through earthworms activity. Atomic absorption spectroscopy (AAS) results reported high level of micronutrient from Eichhornia mediated compost and vermicompost. PMID:25068838

  13. Spectroscopic Analysis of the Supergiant Star HD 54605

    NASA Astrophysics Data System (ADS)

    Peña, L.; Rosenzweig, P.; Guzmán, E.; Hearnshaw, J.

    2009-05-01

    The main purpose of the present study is to analyze a high resolution spectrum of the supergiant star HD 54605, obtained in the year 2003, with a CCD coupled with the spectrograph HERCULES, attached to the 1m reflector telescope of Mt. John Observatory of the University of Canterbury (New Zealand). This spectrum covers the region λλ ≈ 4505-7080Å, with R = 41000 and a dispersion of ≈ 2Å/mm. According to previous spectroscopic observations, of low dispersion, the radial velocity of this star showed that it does not vary in periods of time relatively short. Until the present, we have identified five hundred photospheric lines, from which, with no doubt, we will obtain a satisfactory result that will give an important contribution to the database of the values of the radial velocity of HD 54605. We observe that Hβ, shows a relatively wide and deep profile and is in complete absorption.

  14. Spectroscopic analysis of vermicompost for determination of nutritional quality

    NASA Astrophysics Data System (ADS)

    Subhash Kumar, M.; Rajiv, P.; Rajeshwari, Sivaraj; Venckatesh, Rajendran

    2015-01-01

    Spectroscopic analysis has been carried out to examine the compost quality, maturity and nutritional levels of vermicompost and compost of Eichhornia. 50% Eichhorniacrassipes and 50% cow dung mixtures were vermicomposted using earthworms (Eudrilus eugeniae) and collected on different days' time intervals. Fourier transform infrared spectroscopy (FT-IR) spectra reveal the presence of humic substance from compost and vermicompost, which improves the soil fertility. Gas chromatography-mass spectroscopy (GC-MS) analysis shows maximum level of Benzene propanoic acid (95.98%) and by 2-Propanone, 1-Phenyl-, OXIM (10.10%) from vermicompost through earthworms activity. Atomic absorption spectroscopy (AAS) results reported high level of micronutrient from Eichhornia mediated compost and vermicompost.

  15. Employing Multiple Spectroscopic Techniques Simultaneously to Observe Protein Unfolding

    NASA Astrophysics Data System (ADS)

    Crowe, Michael; Kelty, Ben; Link, Justin

    2015-03-01

    A protein's function is directly related to its native, folded structure. In order to study the structure of proteins, the unfolding process may be characterized. In our study, by using the spectroscopic techniques of circular dichroism (CD), absorption, and fluorescence simultaneously, we examined the unfolding of horse heart cytochrome c, a well-studied, model protein by gradually increasing the concentration of the chemical denaturant, guanidine hydrochloride. The signal changes from these modalities over the course of the unfolding reaction provides some of the thermodynamic properties like Gibbs free energy for insight into the stability of the protein. This allows us to compare the three techniques under the exact same conditions. The objective of this session is to present recent work in developing a protocol to observe the unfolding of cytochrome c using fluorescence, absorbance, and CD simultaneously.

  16. Spectroscopic study of photo and thermal destruction of riboflavin

    NASA Astrophysics Data System (ADS)

    Astanov, Salikh; Sharipov, Mirzo Z.; Fayzullaev, Askar R.; Kurtaliev, Eldar N.; Nizomov, Negmat

    2014-08-01

    Influence of temperature and light irradiation on the spectroscopic properties of aqueous solutions of riboflavin was studied using linear dichroism method, absorption and fluorescence spectroscopy. It was established that in a wide temperature range 290-423 K there is a decline of absorbance and fluorescence ability, which is explained by thermodestruction of riboflavin. It is shown that the proportion of molecules, which have undergone degradation, are in the range of 4-28%, and depends on the concentration and quantity of temperature effects. Introduction of hydrochloric and sulfuric acids, as well as different metal ions leads to an increase in the photostability of riboflavin solutions by 2-2.5 times. The observed phenomena are explained by the formation protonation form of riboflavin and a complex between the metal ions and oxygen atoms of the carbonyl group of riboflavin, respectively.

  17. Spectroscopic Investigations of the Photophysics of Cryptophyte Light-Harvesting

    NASA Astrophysics Data System (ADS)

    Dinshaw, Rayomond

    The biological significance of photosynthesis is indisputable as it is necessary for nearly all life on earth. Photosynthesis provides chemical energy for plants, algae, and bacteria, while heterotrophic organisms rely on these species as their ultimate food source. The initial step in photosynthesis requires the absorption of sunlight to create electronic excitations. Light-harvesting proteins play the functional role of capturing solar radiation and transferring the resulting excitation to the reaction centers where it is used to carry out the chemical reactions of photosynthesis. Despite the wide variety of light-harvesting protein structures and arrangements, most light-harvesting proteins are able to utilize the captured solar energy for charge separation with near perfect quantum efficiency.1 This thesis will focus on understanding the energy transfer dynamics and photophysics of a specific subset of light-harvesting antennae known as phycobiliproteins. These proteins are extracted from cryptophyte algae and are investigated using steady-state and ultrafast spectroscopic techniques.

  18. Imaging, Doppler, and spectroscopic radars from 95 to 700 GHz

    NASA Astrophysics Data System (ADS)

    Cooper, Ken B.

    2016-05-01

    Imaging, Doppler, and spectroscopic radars from 95 to 700 GHz, all using the frequency-modulated continuous-wave technique, are in various stages of development for both defense and science applications at the Jet Propulsion Laboratory. For standoff security screening, a 340 GHz imaging radar now achieves an 8.3 Hz frame, and it has been tested using power-efficient MMIC-based active multiplier sources into its front end. That system evolved from a 680 GHz security radar platform, which has also been modified to operate in a Doppler mode for probing the dynamics of blowing sand and sensing small-amplitude target vibrations. Meanwhile, 95 and 183 GHz radars based on similar RF architectures are currently being developed to probe cometary jets in space and, using a differential absorption technique, humidity inside upper-tropospheric clouds.

  19. Ultrasonic and spectroscopic studies on photoactivation of euglena

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Morita, Shin

    2006-12-01

    We studied the effect of the irradiation wavelength on the activity of photosynthetic euglena. The ultrasonic manipulation technique was used for both the activity evaluation and the movement restriction in the spectral measurements. Euglenas that had been preserved in darkness became inactive, and accordingly most of them were trapped by the ultrasonic standing wave (0.8mW/mm2). However, when they were exposed to light of 500 or 700nm wavelength (0.13W/m2), they became active enough to escape from the trapping. By contrast, irradiation at 550, 600, or 650nm wavelength had no effect on their activity. Spectroscopic measurements, which used to be difficult for locomotive microorganisms, were conducted successfully by trapping euglena at a node of the ultrasonic standing wave. The absorption bands were observed at around 500 or 700nm, which corresponded to the irradiation wavelengths that activated euglena.

  20. Multifunction Imaging and Spectroscopic Instrument

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis

    2004-01-01

    A proposed optoelectronic instrument would perform several different spectroscopic and imaging functions that, heretofore, have been performed by separate instruments. The functions would be reflectance, fluorescence, and Raman spectroscopies; variable-color confocal imaging at two different resolutions; and wide-field color imaging. The instrument was conceived for use in examination of minerals on remote planets. It could also be used on Earth to characterize material specimens. The conceptual design of the instrument emphasizes compactness and economy, to be achieved largely through sharing of components among subsystems that perform different imaging and spectrometric functions. The input optics for the various functions would be mounted in a single optical head. With the exception of a targeting lens, the input optics would all be aimed at the same spot on a specimen, thereby both (1) eliminating the need to reposition the specimen to perform different imaging and/or spectroscopic observations and (2) ensuring that data from such observations can be correlated with respect to known positions on the specimen. The figure schematically depicts the principal components and subsystems of the instrument. The targeting lens would collect light into a multimode optical fiber, which would guide the light through a fiber-selection switch to a reflection/ fluorescence spectrometer. The switch would have four positions, enabling selection of spectrometer input from the targeting lens, from either of one or two multimode optical fibers coming from a reflectance/fluorescence- microspectrometer optical head, or from a dark calibration position (no fiber). The switch would be the only moving part within the instrument.

  1. Spectroscopic Studies of Abell Clusters

    NASA Astrophysics Data System (ADS)

    Way, Michael Joseph

    The objectives of this work are to use spectroscopic techniques to accurately categorize galaxies as either HII region star forming galaxies or as Active Galactic Nuclei powered via a black hole, and to use radial velocities and projected positions of galaxies in clusters to obtain the total cluster mass and its distribution. The masses and distributions compare well to X-ray mass measurements. The commonly used Dressler, A., Thompson, I. & Shectman, S. 1985, ApJ, 288, 481 technique for discriminating between Active Galactic Nuclei and HII region galaxies uses the measurement of the equivalent width of the emission lines (OII) 3727 A, H/beta, and (OIII) 5007 A. High quality spectra from 42 galaxies were taken and it is shown that their method is not capable of distinguishing between Active Galactic Nuclei and HII region galaxies. The emission line flux from H/beta, (OIII) 5007 A, (OI) 6300 A, Hα, (NII) 6583 A, and (SII) 6716+6731 A in combination with the method of Veilleux, S. & Osterbrock, D. E. 1987, ApJS, 63, 295 must be used to accurately distinguish between Active Galactic Nuclei and HII region galaxies. Galaxy radial velocities from spectroscopic data and their projected 2-D positions in clusters are used to obtain robust estimates of the total mass and mass distribution in two clusters. The total mass is calculated using the Virial theorem after removing substructure. The mass distribution is estimated via several robust statistical tests for 1-D, 2-D and 3-D structure. It is shown that the derived mass estimates agree well with those found independently from hot X-ray gas emission in clusters.

  2. The 2003 edition of the GEISA/IASI spectroscopic database

    NASA Astrophysics Data System (ADS)

    Jacquinet-Husson, N.; Scott, N. A.; Chédin, A.; Garceran, K.; Armante, R.; Chursin, A. A.; Barbe, A.; Birk, M.; Brown, L. R.; Camy-Peyret, C.; Claveau, C.; Clerbaux, C.; Coheur, P. F.; Dana, V.; Daumont, L.; Debacker-Barilly, M. R.; Flaud, J. M.; Goldman, A.; Hamdouni, A.; Hess, M.; Jacquemart, D.; Köpke, P.; Mandin, J. Y.; Massie, S.; Mikhailenko, S.; Nemtchinov, V.; Nikitin, A.; Newnham, D.; Perrin, A.; Perevalov, V. I.; Régalia-Jarlot, L.; Rublev, A.; Schreier, F.; Schult, I.; Smith, K. M.; Tashkun, S. A.; Teffo, J. L.; Toth, R. A.; Tyuterev, Vl. G.; Vander Auwera, J.; Varanasi, P.; Wagner, G.

    2005-11-01

    The content of the current (2003) version, GEISA/IASI-03, of the computer-accessible spectroscopic database, GEISA/IASI, is described. This “system” or database is comprised of three independent spectroscopic archives, which are (a) a database of individual spectral line parameters on 14 molecules, H2O, CO2, O3, N2O, CO, CH4, O2, NO, SO2, NO2, HNO3, OCS, C2H2, N2, and the related 51 isotopomers and isotopologues, representing 702,550 entries, in the spectral range 599 3001cm, (b) a database of spectral absorption cross-sections (6,572,329 entries related to six molecules, CFC-11, CFC-12, CFC-14, HCFC-22, N2O5, CCl4), and a catalogue of microphysical and optical properties (mainly, the refractive indices) of atmospheric aerosols. The modifications and improvements, which have been implemented since the earlier editions of this database, in terms of content and management, have been explained in detail. GEISA/IASI has been created with the specific purpose of assessing the capability of measurement by the IASI instrument within the designated goals of ISSWG in the frame of the CNES/EUMETSAT European Polar System preparation. All the archived data can be handled through a user-friendly associated management software, which is posted on the ARA/LMD group web site at http://ara.lmd.polytechnique.fr.

  3. Atmospheric and Spectroscopic Research in the Far Infrared

    NASA Technical Reports Server (NTRS)

    Park, Kwangjai

    1998-01-01

    The spectroscopic measurements of molecular parameters constitute one of the major areas of our research program. This part of our program has been conducted in close collaboration with Smithsonian Astrophysical Observatory (SAO) and National Institute of Standards and Technology (NIST). The references on HO2, OH, and O2 that appear on the publication list are examples of this type of work completed during the grant period. These pressure-broadening studies have provided the kind of improvements needed in the database for retrieving atmospheric profiles from far infrared limb sensing data. Authors summarized the laboratory spectroscopic studies conducted during the grant period. We attempted to measure the pressure broadening coefficients of the O2 lines in the 50 and 117/ cm regions. An accurate characterization of these lines using the IBEX detector system was needed to analyze the flight data. These are difficult lines to measure because they arise from weak magnetic dipole transitions. We used a 4-meter absorption cell to obtain the pressure broadening coefficients for the 50 and 83 /cm lines. We also completed the pressure broadening studies including the temperature dependence of two lines of OH at 83 and 118 /cm. These two lines are important not only for the balloon data retrieval work but also for the future project proposals.Another area of focus in our program is the far infrared detector research. The third area of focus deals with data distribution and dissemination.

  4. Novel dipodal Schiff base compounds: Synthesis, characterization and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Obali, Aslihan Yilmaz; Ucan, Halil Ismet

    2015-02-01

    Two novel dipodal Schiff base compounds 1,2-benzyloxy-bis-[2-(benzylideneamino)phenol, L1 and 1,2-benzyloxy-bis[3-(benzylideneamino)pyridine], L2 were synthesized. Their sensing actions were confirmed by UV-Vis absorbance and emission spectroscopic studies in presence of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II) in methanol medium (1 × 10-4 M). It was found that the dipodal compounds can selectively bind to Cu(II) and Pb(II) metal ions with a significant change in its emission and absorption spectra, while the addition of other metal ions (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II)) produces insignificant or minor changes. The host-guest complexes formed were determined by Job's plot method. As a chemosensor, L1 and L2 dipodal Schiff base compounds shows a specific selectivity towards Cu(II) and Pb(II) ions in according to all spectroscopic data.

  5. SSGSS: THE SPITZER-SDSS-GALEX SPECTROSCOPIC SURVEY

    SciTech Connect

    O'Dowd, Matthew J.; Schiminovich, David; Johnson, Benjamin D.; Treyer, Marie A.; Martin, Christopher D.; Wyder, Ted K.; Charlot, Stephane; Heckman, Timothy M.; Martins, Lucimara P.; Seibert, Mark; Van der Hulst, J. M.

    2011-11-10

    The Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS) provides a new sample of 101 star-forming galaxies at z < 0.2 with unprecedented multi-wavelength coverage. New mid- to far-infrared spectroscopy from the Spitzer Space Telescope is added to a rich suite of previous imaging and spectroscopy, including ROSAT, Galaxy Evolution Explorer, Sloan Digital Sky Survey, Two Micron All Sky Survey, and Spitzer/SWIRE. Sample selection ensures an even coverage of the full range of normal galaxy properties, spanning two orders of magnitude in stellar mass, color, and dust attenuation. In this paper we present the SSGSS data set, describe the science drivers, and detail the sample selection, observations, data reduction, and quality assessment. Also in this paper, we compare the shape of the thermal continuum and the degree of silicate absorption of these typical, star-forming galaxies to those of starburst galaxies. We investigate the link between star formation rate, infrared luminosity, and total polycyclic aromatic hydrocarbon luminosity, with a view to calibrating the latter for spectral energy distribution models in photometric samples and at high redshift. Last, we take advantage of the 5-40 {mu}m spectroscopic and far-infrared photometric coverage of this sample to perform detailed fitting of the Draine et al. dust models, and investigate the link between dust mass and star formation history and active galactic nucleus properties.

  6. High Definition Infrared Spectroscopic Imaging for Lymph Node Histopathology

    PubMed Central

    Leslie, L. Suzanne; Wrobel, Tomasz P.; Mayerich, David; Bindra, Snehal; Emmadi, Rajyasree; Bhargava, Rohit

    2015-01-01

    Chemical imaging is a rapidly emerging field in which molecular information within samples can be used to predict biological function and recognize disease without the use of stains or manual identification. In Fourier transform infrared (FT-IR) spectroscopic imaging, molecular absorption contrast provides a large signal relative to noise. Due to the long mid-IR wavelengths and sub-optimal instrument design, however, pixel sizes have historically been much larger than cells. This limits both the accuracy of the technique in identifying small regions, as well as the ability to visualize single cells. Here we obtain data with micron-sized sampling using a tabletop FT-IR instrument, and demonstrate that the high-definition (HD) data lead to accurate identification of multiple cells in lymph nodes that was not previously possible. Highly accurate recognition of eight distinct classes - naïve and memory B cells, T cells, erythrocytes, connective tissue, fibrovascular network, smooth muscle, and light and dark zone activated B cells was achieved in healthy, reactive, and malignant lymph node biopsies using a random forest classifier. The results demonstrate that cells currently identifiable only through immunohistochemical stains and cumbersome manual recognition of optical microscopy images can now be distinguished to a similar level through a single IR spectroscopic image from a lymph node biopsy. PMID:26039216

  7. Spectroscopic properties of Martian meteorite ALH84001 and identification of minerals and organic species

    NASA Astrophysics Data System (ADS)

    Bishop, J. L.; Pieters, C. M.; Hiroi, T.

    1997-03-01

    Chemical and mineralogical analyses of the Martian meteorite ALH84001 have shown that it contains primarily orthopyroxene, which differentiates it from other Martian meteorites. Detailed spectroscopic analyses of multiple chip surfaces and a particulate sample of ALH84001 are presented here. The IR spectra of the chip and powder samples exhibit features characteristic of several minerals. The 5-25-micron spectra of ALH84001 are especially difficult to interpret because of multiple mineral components and particle size variations.

  8. Combined spectroscopic and quantum chemical studies of ezetimibe

    NASA Astrophysics Data System (ADS)

    Prajapati, Preeti; Pandey, Jaya; Shimpi, Manishkumar R.; Srivastava, Anubha; Tandon, Poonam; Velaga, Sitaram P.; Sinha, Kirti

    2016-12-01

    Ezetimibe (EZT) is a hypocholesterolemic agent used for the treatment of elevated blood cholesterol levels as it lowers the blood cholesterol by blocking the absorption of cholesterol in intestine. Study aims to combine experimental and computational methods to provide insights into the structural and vibrational spectroscopic properties of EZT which is important for explaining drug substance physical and biological properties. Computational study on molecular properties of ezetimibe is presented using density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set. A detailed vibrational assignment has been done for the observed IR and Raman spectra of EZT. In addition to the conformational study, hydrogen bonding and molecular docking studies have been also performed. For conformational studies, the double well potential energy curves have been plotted for the rotation around the six flexible bonds of the molecule. UV absorption spectrum was examined in methanol solvent and compared with calculated one in solvent environment (IEF-PCM) using TD-DFT/6-31G basis set. HOMO-LUMO energy gap of both the conformers have also been calculated in order to predict its chemical reactivity and stability. The stability of the molecule was also examined by means of natural bond analysis (NBO) analysis. To account for the chemical reactivity and site selectivity of the molecules, molecular electrostatic potential (MEPS) map has been plotted. The combination of experimental and calculated results provide an insight into the structural and vibrational spectroscopic properties of EZT. In order to give an insight for the biological activity of EZT, molecular docking of EZT with protein NPC1L1 has been done.

  9. Catalysts at work: From integral to spatially resolved X-ray absorption spectroscopy

    SciTech Connect

    Grunwaldt, Jan-Dierk; Kimmerle, Bertram; Baiker, Alfons; Boye, Pit; Schroer, Christian G.; Glatzel, Pieter; Borca, Camelia N.; Beckmann, Felix

    2009-09-25

    Spectroscopic studies on heterogeneous catalysts have mostly been done in an integral mode. However, in many cases spatial variations in catalyst structure can occur, e.g. during impregnation of pre-shaped particles, during reaction in a catalytic reactor, or in microstructured reactors as the present overview shows. Therefore, spatially resolved molecular information on a microscale is required for a comprehensive understanding of theses systems, partly in ex situ studies, partly under stationary reaction conditions and in some cases even under dynamic reaction conditions. Among the different available techniques, X-ray absorption spectroscopy (XAS) is a well-suited tool for this purpose as the different selected examples highlight. Two different techniques, scanning and full-field X-ray microscopy/tomography, are described and compared. At first, the tomographic structure of impregnated alumina pellets is presented using full-field transmission microtomography and compared to the results obtained with a scanning X-ray microbeam technique to analyse the catalyst bed inside a catalytic quartz glass reactor. On the other hand, by using XAS in scanning microtomography, the structure and the distribution of Cu(0), Cu(I), Cu(II) species in a Cu/ZnO catalyst loaded in a quartz capillary microreactor could be reconstructed quantitatively on a virtual section through the reactor. An illustrating example for spatially resolved XAS under reaction conditions is the partial oxidation of methane over noble metal-based catalysts. In order to obtain spectroscopic information on the spatial variation of the oxidation state of the catalyst inside the reactor XAS spectra were recorded by scanning with a micro-focussed beam along the catalyst bed. Alternatively, full-field transmission imaging was used to efficiently determine the distribution of the oxidation state of a catalyst inside a reactor under reaction conditions. The new technical approaches together with quantitative data

  10. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  11. Investigating a physical basis for spectroscopic estimates of leaf nitrogen concentration

    USGS Publications Warehouse

    Kokaly, R.F.

    2001-01-01

    The reflectance spectra of dried and ground plant foliage are examined for changes directly due to increasing nitrogen concentration. A broadening of the 2.1-??m absorption feature is observed as nitrogen concentration increases. The broadening is shown to arise from two absorptions at 2.054 ??m and 2.172 ??m. The wavelength positions of these absorptions coincide with the absorption characteristics of the nitrogen-containing amide bonds in proteins. The observed presence of these absorption features in the reflectance spectra of dried foliage is suggested to form a physical basis for high correlations established by stepwise multiple linear regression techniques between the reflectance of dry plant samples and their nitrogen concentration. The consistent change in the 2.1-??m absorption feature as nitrogen increases and the offset position of protein absorptions compared to those of other plant components together indicate that a generally applicable algorithm may be developed for spectroscopic estimates of nitrogen concentration from the reflectance spectra of dried plant foliage samples. ?? 2001 Published by Elsevier Science Ireland Ltd.

  12. Chaotic systems with absorption.

    PubMed

    Altmann, Eduardo G; Portela, Jefferson S E; Tél, Tamás

    2013-10-01

    Motivated by applications in optics and acoustics we develop a dynamical-system approach to describe absorption in chaotic systems. We introduce an operator formalism from which we obtain (i) a general formula for the escape rate κ in terms of the natural conditionally invariant measure of the system, (ii) an increased multifractality when compared to the spectrum of dimensions D(q) obtained without taking absorption and return times into account, and (iii) a generalization of the Kantz-Grassberger formula that expresses D(1) in terms of κ, the positive Lyapunov exponent, the average return time, and a new quantity, the reflection rate. Simulations in the cardioid billiard confirm these results. PMID:24138240

  13. The Young Solar Analogs Project. I. Spectroscopic and Photometric Methods and Multi-year Timescale Spectroscopic Results

    NASA Astrophysics Data System (ADS)

    Gray, R. O.; Saken, J. M.; Corbally, C. J.; Briley, M. M.; Lambert, R. A.; Fuller, V. A.; Newsome, I. M.; Seeds, M. F.; Kahvaz, Y.

    2015-12-01

    This is the first in a series of papers presenting methods and results from the Young Solar Analogs Project, which began in 2007. This project monitors both spectroscopically and photometrically a set of 31 young (300-1500 Myr) solar-type stars with the goal of gaining insight into the space environment of the Earth during the period when life first appeared. From our spectroscopic observations we derive the Mount Wilson S chromospheric activity index (SMW), and describe the method we use to transform our instrumental indices to SMW without the need for a color term. We introduce three photospheric indices based on strong absorption features in the blue-violet spectrum—the G-band, the Ca i resonance line, and the Hydrogen-γ line—with the expectation that these indices might prove to be useful in detecting variations in the surface temperatures of active solar-type stars. We also describe our photometric program, and in particular our "Superstar technique" for differential photometry which, instead of relying on a handful of comparison stars, uses the photon flux in the entire star field in the CCD image to derive the program star magnitude. This enables photometric errors on the order of 0.005-0.007 magnitude. We present time series plots of our spectroscopic data for all four indices, and carry out extensive statistical tests on those time series demonstrating the reality of variations on timescales of years in all four indices. We also statistically test for and discover correlations and anti-correlations between the four indices. We discuss the physical basis of those correlations. As it turns out, the "photospheric" indices appear to be most strongly affected by emission in the Paschen continuum. We thus anticipate that these indices may prove to be useful proxies for monitoring emission in the ultraviolet Balmer continuum. Future papers in this series will discuss variability of the program stars on medium (days-months) and short (minutes to hours

  14. Pathways of iron absorption.

    PubMed

    Conrad, Marcel E; Umbreit, Jay N

    2002-01-01

    Iron is vital for all living organisms but excess iron can be lethal because it facilitates free radical formation. Thus iron absorption is carefully regulated to maintain an equilibrium between absorption and body loss of iron. In countries where meat is a significant part of the diet, most body iron is derived from dietary heme because heme binds few of the dietary chelators that bind inorganic iron. Uptake of heme into enterocytes occurs as a metalloporphyrin in an endosomal process. Intracellular iron is released from heme by heme oxygenase to enter plasma as inorganic iron. Ferric iron is absorbed via a beta(3) integrin and mobilferrin pathway (IMP) which is unshared with other nutritional metals. Ferrous iron uptake is facilitated by a DMT-1 pathway which is shared with manganese. In the iron deficient gut, large quantities of both mobilferrin and DMT-1 are found in goblet cells and intraluminal mucins suggesting that they are secreted with mucin into the intestinal lumen to bind iron to facilitate uptake by the cells. In the cytoplasm, IMP and DMT associate in a large protein complex called paraferritin which serves as a ferrireductase. Paraferritin solublizes iron binding proteins and reduces iron to make iron available for production of iron containing proteins such as heme. Iron uptake by intestinal absorptive cells is regulated by the iron concentration within the cell. Except in hemochromatosis it remains in equilibrium with total body stores via transferrin receptors on the basolateral membrane of absorptive cells. Increased intracellular iron either up-regulates or satiates iron binding proteins on regulatory proteins to alter their location in the intestinal mucosa. PMID:12547224

  15. The Fourier transform absorption spectrum of acetylene between 8280 and 8700 cm-1

    NASA Astrophysics Data System (ADS)

    Lyulin, O. M.; Vander Auwera, J.; Campargue, A.

    2016-07-01

    High resolution (0.011 cm-1) room temperature (295 K) Fourier transform absorption spectra (FTS) of acetylene have been analyzed in the 8280-8700 cm-1 range dominated by the ν1+ν2+ν3 band at 8512 cm-1. Line positions and intensities were retrieved from FTS spectra recorded at 3.84 and 56.6 hPa. As a result, a list of 1001 lines was constructed with intensities ranging between about 2×10-26 and 10-22 cm/molecule. Comparison with accurate predictions provided by a global effective operator model led to the assignment of 629 12C2H2 lines. In addition, 114 lines of the 13C12CH2 isotopologue were assigned using information available in the literature. The 12C2H2 lines belong to thirteen bands, nine of which being newly reported. The 13C12CH2 lines belong to three bands, the intensities of which being reported for the first time. Spectroscopic parameters of the 12C2H2 upper vibrational levels were derived from band-by-band analyses of the line positions (typical rms are on the order of 0.002 cm-1). Three of the analyzed bands were found to be affected by rovibrational perturbations, which are discussed in the frame of a global effective Hamiltonian. The obtained line parameters are compared with those of the two bands included in the HITRAN 2012 database.

  16. Relic Neutrino Absorption Spectroscopy

    SciTech Connect

    Eberle, b

    2004-01-28

    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.

  17. Sequential Extraction and Spectroscopic Characterisation of Organic Matter from the Callovo-Oxfordian Formation

    SciTech Connect

    Grasset, L.; Brevet, J; Schäfer, T; Claret, F; Gaucher, E; Albrecht, A; Amblès, A

    2010-01-01

    One site under consideration for the disposal of medium and high level, long lived radioactive waste is in the eastern part of the Paris Basin (Meuse/Haute Marne, France), where the National Radioactive Waste Management Agency (ANDRA) operates an underground laboratory. The sedimentary host formation is a 130 m thick, clay-rich Callovo-Oxfordian deposit ca. 350-550 m below ground in the selected area. The major fraction (>95%) of the organic matter (OM) is associated with minerals. In order to better understand the importance of OM on the chemistry of this formation, we have developed a protocol allowing extraction/fractionation of organic compounds in the rocks. The protocol is based on classical methods currently used for the isolation of humic substances from soils and for the separation of kerogen in ancient sediments using sequential extraction with solvents and water at different pH value. This allows us to the remove a large part of the minerals and to suspend almost all (>90%) of the OM (associated with residual recalcitrant minerals) in water. The OM can then be analysed via spectroscopic methods, such as mass spectrometry (MS), Fourier transform infra-red spectroscopy (FTIR), or C (1s) near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The molecular composition of the solvent-soluble, directly-extractable part shows the OM to be thermally immature. The solvent-soluble fractions obtained after acid and alkaline treatments are mostly polar in nature and have a high degree of aliphaticity. C(1s) NEXAFS analysis of water soluble organic fractions indicates a progressive increase in aliphaticity and a decrease in carboxylic/carbonyl groups with consecutive extraction steps.

  18. Fingerprints of polycyclic aromatic hydrocarbons (PAHs) in infrared absorption spectroscopy.

    PubMed

    Tommasini, Matteo; Lucotti, Andrea; Alfè, Michela; Ciajolo, Anna; Zerbi, Giuseppe

    2016-01-01

    We have analyzed a set of 51 PAHs whose structures have been hypothesized from mass spectrometry data collected on samples extracted from carbon particles of combustion origin. We have obtained relationships between infrared absorption signals in the fingerprint region (mid-IR) and the chemical structures of PAHs, thus proving the potential of IR spectroscopy for the characterization of the molecular structure of aromatic combustion products. The results obtained here for the spectroscopic characterization of PAHs can be also of interest in Materials Science and Astrophysics. PMID:26208268

  19. Fingerprints of polycyclic aromatic hydrocarbons (PAHs) in infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Tommasini, Matteo; Lucotti, Andrea; Alfè, Michela; Ciajolo, Anna; Zerbi, Giuseppe

    2016-01-01

    We have analyzed a set of 51 PAHs whose structures have been hypothesized from mass spectrometry data collected on samples extracted from carbon particles of combustion origin. We have obtained relationships between infrared absorption signals in the fingerprint region (mid-IR) and the chemical structures of PAHs, thus proving the potential of IR spectroscopy for the characterization of the molecular structure of aromatic combustion products. The results obtained here for the spectroscopic characterization of PAHs can be also of interest in Materials Science and Astrophysics.

  20. A model for oxygen-dependent backscattering spectroscopic contrast from single red blood cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Rongrong; Yi, Ji; Chen, Siyu; Zhang, Hao F.; Backman, Vadim

    2016-03-01

    The oxygen-dependent absorption of hemoglobin provides the fundamental contrast for all label-free techniques measuring blood oxygenation. When hemoglobin is packaged into red blood cells (RBCs), the structure of the cells creates light scattering which also depends on the absorption based on the Kramers-Kronig relationship. Thus a proper characterization of the optical behaviors of blood has been a key to any accurate measurement of blood oxygenation, particularly at the capillary level where RBCs are dispersed individually in contrast to a densely packed whole blood. Here we provided a theoretical model under Born Approximation to characterize the oxygen dependent backscattering spectroscopic contrast from single RBCs. Using this theoretical model, we conducted simulations on both oxygenated and deoxygenated single RBCs with different sizes for standard and possible deformed cell geometries in blood flow, all which suggested similar backscattering spectroscopic contrast and were confirmed by Mie Theory and experiments using visible Optical Coherence Tomography (visOCT). As long as the cell size satisfies Gaussian distribution with a coefficient variance (C.V.) large enough, there is clear absorption contrast between the backscattering spectra of oxygenated and deoxygenated single RBCs calculated by this model, so oxygen saturation can then be characterized. Thus, this theoretical model can be extended to extract absorption features of other scattering particles as long as they satisfy Born Approximation.

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

    PubMed Central

    Wang, Chuji; Sahay, Peeyush

    2009-01-01

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

  2. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  3. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.; Bauguitte, S. J.-B.; O'Shea, S. J.; Muller, J. B. A.; Zahniser, M. S.; Pyle, J.; Palmer, P. I.

    2015-08-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We present details of the mid-IR Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure is presented. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA). Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

  4. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M. R.; Allen, G.; Percival, C.; Gallagher, M. W.; Bauguitte, S.; O'Shea, S.; Muller, J.; Zahniser, M. S.; Pyle, J. A.; Palmer, P. I.

    2015-12-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We evaluate the performance of the mid-IR continuous wave Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. Test flight data demonstrating the sensitivity of the instrument to changes in cabin pressure is presented, and a new in-flight calibration procedure to account for this issue is described and assessed. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA).

  5. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, Joseph; Le Breton, Michael; Allen, Grant; Percival, Carl; Gallagher, Martin; Bauguitte, Stephane; O'Shea, Sebastian; Muller, Jennifer; Zahniser, Mark; Pyle, John; Palmer, Paul

    2016-04-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We evaluate the performance of the mid-IR continuous wave Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. Test flight data demonstrating the sensitivity of the instrument to changes in cabin pressure is presented, and a new in-flight calibration procedure to account for this issue is described and assessed. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA).

  6. The development and evaluation of airborne in situ N2O and CH4 sampling using a quantum cascade laser absorption spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.; Bauguitte, S. J.-B.; O'Shea, S. J.; Muller, J. B. A.; Zahniser, M. S.; Pyle, J.; Palmer, P. I.

    2016-01-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large atmospheric research aircraft. We present details of the mid-infrared quantum cascade laser absorption spectrometer (QCLAS, Aerodyne Research Inc., USA) employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure are presented. Total 1σ uncertainties of 2.47 ppb for CH4 and 0.54 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Fast Greenhouse Gas Analyser (FGGA, Los Gatos Research, USA). Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

  7. Syntheses, spectroscopic and thermal analyses of cyanide bridged heteronuclear polymeric complexes: [M(L)2Ni(CN)4]n (Ldbnd N-methylethylenediamine or N-ethylethylenediamine; Mdbnd Ni(II), Cu(II), Zn(II) or Cd(II))

    NASA Astrophysics Data System (ADS)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla

    2016-02-01

    Polymeric tetracyanonickelate(II) complexes of the type [M(L)2Ni(CN)4]n (Ldbnd N-methylethylenediamine (men) or N-ethylethylenediamine (neen); Mdbnd Ni(II), Cu(II), Zn(II) or Cd(II)) have been prepared and characterized by FT-IR, Raman spectroscopy, thermal and elemental analysis techniques. Additionally, FT-IR and Raman spectral analyses of men and neen have experimentally and theoretically investigated in the range of 4000-250 cm-1. The corresponding vibration assignments of men and neen are performed by using B3LYP density functional theory (DFT) method together with 6-31 G(d) basis set. The spectral features of the complexes suggest that the coordination environment of the M(II) ions are surrounded by the two symmetry related men and neen ligands and the two symmetry related N atom of cyanide groups, whereas the Ni(II) atoms are coordinated with a square-planar to four C atoms of the cyanide groups. Polymeric structures of the complexes consist of one dimensional alternative chains of [M(L)2]2+ and [Ni(CN)4]2- moieties. The thermal decompositions in the temperature range 30-700 °C of the complexes were investigated in the static air atmosphere.

  8. NMR-spectroscopic analysis of mixtures: from structure to function

    PubMed Central

    Forseth, Ry R.; Schroeder, Frank C.

    2010-01-01

    NMR spectroscopy as a particularly information-rich method offers unique opportunities for improving the structural and functional characterization of metabolomes, which will be essential for advancing the understanding of many biological processes. Whereas traditionally NMR spectroscopy was mostly relegated to the characterization of pure compounds, the last few years have seen a surge of interest in using NMR spectroscopic techniques for characterizing complex metabolite mixtures. Development of new methods was motivated partly by the realization that using NMR for the analysis of metabolite mixtures can help identify otherwise inaccessible small molecules, for example compounds that are prone to chemical decomposition and thus cannot be isolated. Furthermore, comparative metabolomics and statistical analyses of NMR-spectra have proven highly effective at identifying novel and known metabolites that correlate with changes in genotype or phenotype. In this review, we provide an overview of the range of NMR spectroscopic techniques recently developed for characterizing metabolite mixtures, including methods used in discovery-oriented natural product chemistry, in the study of metabolite biosynthesis and function, or for comparative analyses of entire metabolomes. PMID:21071261

  9. Spectroscopic analysis of Martian meteorite ALH 84001 powder and applications for spectral identification of minerals and other soil components on Mars

    NASA Astrophysics Data System (ADS)

    Bishop, Janice L.; Pieters, Carle M.; Hiroi, Takahiro; Mustard, John F.

    1998-07-01

    Spectroscopic measurement and analysis of Martian meteorites provide important information about the mineralogy of Mars, as well as necessary ground-truths for deconvolving remote sensing spectra of the Martian surface rocks. The spectroscopic properties of particulate ALH 84001 from 0.3 to 25 (m correctly identify low-Ca-pyroxene as the dominant mineralogy. Absorption bands due to electronic transitions of ferrous iron are observed at 0.94 and 1.97 (m that are typical for low-Ca-pyroxene. A strong, broad water band is observed near 3 (m that is characteristic of the water band typically associated with pyroxenes. Weaker features near 4.8, 5.2 and 6.2 (m are characteristic of particulate low-Ca-pyroxene, and can be readily distinguished from the features due to high-Ca-pyroxene and other silicate minerals. The reflectance minimum occurs near 8.6 (m for the ALH 84001 powder, which is more consistent with high-Ca-pyroxene and augite than low-Ca-pyroxene. The dominant mid-IR spectral features for the ALH 84001 powder are observed near 9 and 19.5 (m; however, there are multiple features in this region. These mid-IR features are generally characteristic of low-Ca-pyroxene, but cannot be explained by low-Ca-pyroxene alone. Spectral features from 2.5-5 (m are typically associated with water, organics and carbonates and have been studied in spectra of the ALH 84001, split 92 powder and ALH 84001, splits 92 and 271 chip surfaces. Weak features have been identified near 3.5 and 4 (m that are assigned to organic material and carbonates. Another feature is observed at 4.27 (m in many surface spots and in the powder, but has not yet been uniquely identified. Spectroscopic identification of minor organic and carbonate components in this probable piece of Mars suggests that detection of small amounts of organics and carbonates in the Martian surface regolith would also be possible using visible-infrared hyperspectral analyses. Laboratory spectroscopic analysis of Martian

  10. DATA AND ANALYSES

    EPA Science Inventory

    In order to promote transparency and clarity of the analyses performed in support of EPA's Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens, the data and the analyses are now available on this web site. The data is presented in two diffe...

  11. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  12. Spectroscopic characterization of uranium in evaporation basin sediments

    NASA Astrophysics Data System (ADS)

    Duff, M. C.; Morris, D. E.; Hunter, D. B.; Bertsch, P. M.

    2000-05-01

    Evaporation ponds in the San Joaquin Valley (SJV), CA, used for the containment of irrigation drainage waters contain elevated levels of uranium (U) resulting from the extensive leaching by carbonate-rich irrigation waters of the local agricultural soils that contain low levels of naturally-occurring U. The SJV ponds are subjected to changes in redox chemistry with cycles of drying and flooding. Our past studies have shown that U in the SJV Pond 14 surface sediments is present as mostly the oxidized and soluble form, U(VI). However, we were uncertain whether the U in the soil was only present as a U oxide of mixed stoichiometry, such as U 3O 8(s) (pitchblende) or other species. Here we present characterization information, which includes wet chemical and in situ spectroscopic techniques (X-ray absorption near-edge structure (XANES) and low temperature time-resolved luminescence spectroscopies) for samples from two SJV Pond sediments. Surface sediments from SJV Pond 16 were characterized for average oxidation state of U with XANES spectroscopy. The fraction of U(VI) to U(IV) in the Pond 16 sediments decreased with depth with U(IV) being the dominant oxidation state in the 5 cm to 15 cm depth. Two luminescent U(VI) species were identified in the surface sediments from Pond 14; a U(VI)-tricarbonate phase and another phase likely comprised of U(VI)-hydroxide or hydroxycarbonate. The luminescent U(VI) population in the Pond 16 sediments is dominated by species with comparable spectral characteristics to the U(VI)-hydroxide or hydroxycarbonate species found in the Pond 14 sediments. The luminescence spectroscopic results were complemented by wet chemical U leaching methods, which involved the use of carbonate and sulfuric acid solutions and oxidizing solutions of peroxide, hypochlorite and Mn(IV). Leaching was shown to decrease the total U concentration in the sediments in all cases. However, results from luminescence studies of the residual fraction in the leached

  13. A spectroscopic transfer standard for accurate atmospheric CO measurements

    NASA Astrophysics Data System (ADS)

    Nwaboh, Javis A.; Li, Gang; Serdyukov, Anton; Werhahn, Olav; Ebert, Volker

    2016-04-01

    Atmospheric carbon monoxide (CO) is a precursor of essential climate variables and has an indirect effect for enhancing global warming. Accurate and reliable measurements of atmospheric CO concentration are becoming indispensable. WMO-GAW reports states a compatibility goal of ±2 ppb for atmospheric CO concentration measurements. Therefore, the EMRP-HIGHGAS (European metrology research program - high-impact greenhouse gases) project aims at developing spectroscopic transfer standards for CO concentration measurements to meet this goal. A spectroscopic transfer standard would provide results that are directly traceable to the SI, can be very useful for calibration of devices operating in the field, and could complement classical gas standards in the field where calibration gas mixtures in bottles often are not accurate, available or stable enough [1][2]. Here, we present our new direct tunable diode laser absorption spectroscopy (dTDLAS) sensor capable of performing absolute ("calibration free") CO concentration measurements, and being operated as a spectroscopic transfer standard. To achieve the compatibility goal stated by WMO for CO concentration measurements and ensure the traceability of the final concentration results, traceable spectral line data especially line intensities with appropriate uncertainties are needed. Therefore, we utilize our new high-resolution Fourier-transform infrared (FTIR) spectroscopy CO line data for the 2-0 band, with significantly reduced uncertainties, for the dTDLAS data evaluation. Further, we demonstrate the capability of our sensor for atmospheric CO measurements, discuss uncertainty calculation following the guide to the expression of uncertainty in measurement (GUM) principles and show that CO concentrations derived using the sensor, based on the TILSAM (traceable infrared laser spectroscopic amount fraction measurement) method, are in excellent agreement with gravimetric values. Acknowledgement Parts of this work have been

  14. Spectroscopic analysis of chromium bioremediation products

    NASA Astrophysics Data System (ADS)

    Varadharajan, C.; Nico, P. S.; Yang, L.; Marcus, M. A.; Steefel, C.; Larsen, J. T.; Beller, H. R.; Brodie, E. L.

    2010-12-01

    Remediation of chromium contamination frequently involves reducing the toxic and soluble hexavalent form, Cr(VI), to the relatively harmless and mostly immobile trivalent state, Cr(III). The objective of this study is to identify the biogeochemical reactions that control in situ chromium reduction in the presence of different dominant electron acceptors, i.e., NO3-, Fe(III), and SO42-. It was hypothesized that indirect, abiotic reduction of Cr(VI) by reduced metabolic products [Fe(II) and sulfides] would dominate over direct enzymatic reduction by denitrifying, iron-reducing, or sulfate-reducing bacteria. It is further hypothesized that the enzymatic reduction of Cr(VI) would produce relatively pure chromium hydroxide precipitates, whereas indirect reduction would result in mixed Cr-Fe hydroxide solid phases. Flow-through columns containing homogenized sediments from the 100H site at Hanford, WA were subjected to nitrate-, sulfate- or iron-reducing conditions in the presence of 5 µM Cr(VI) and 5 mM lactate. Cr(VI) was depleted in the effluent solutions from the nitrate- and sulfate-reducing columns; however only a small amount of Cr(VI) was removed under iron-reducing conditions. Preliminary analysis of micro X-ray absorption spectra indicate that the untreated and iron-reducing column sediments contained pre-existing Cr in the form of primary minerals, e.g. chromite and/or Cr-bearing micas. However, there was an increase in the relative abundance of mixed-phase Cr-Fe hydroxides, i.e., Cr1-xFex(OH)3 in the nitrate- and sulfate-treated columns. A possible explanation for the observations is that the production of Fe(II) was enhanced under the nitrate- and sulfate- reducing conditions, and was most likely sulfide-driven in the latter case. The Fe(II) was subsequently available for reduction of Cr(VI) resulting in the mixed-phase precipitates. The results from the spectroscopic analysis support the hypothesis that Fe(II)-mediated Cr reduction prevails over direct

  15. The effect of some beverage extracts on intestinal iron absorption.

    PubMed

    el-Shobaki, F A; Saleh, Z A; Saleh, N

    1990-12-01

    The effect of some beverage extracts namely anise, mint, caraway, cumin, tilia, liquorice, karkade and tea, on the absorption of iron was tested in tied-off intestinal segments of rats. The rate of intestinal iron absorption was calculated in terms of an absorption index. The tannin, phytic acid and ascorbic acid contents of these beverages were analysed. The results show that anise, mint, caraway, cumin, tilia, liquorice, arranged in decreasing order of their effect, promoted the absorption of iron. Karkade did not exert an appreciable effect while tea inhibited absorption. The results are discussed in relation to the content of these beverages of tannins, phytic or ascorbic acids. It is recommended to offer these beverages to children and also to adults as a preventive agent to iron deficiency anemia. Also can be used for the preparation of bioavailable medicinal iron. PMID:2080638

  16. Thin-film spectroscopic sensor

    DOEpatents

    Burgess, Jr., Lloyd W.; Goldman, Don S.

    1992-01-01

    There is disclosed an integrated spectrometer for chemical analysis by evanescent electromagnetic radiation absorption in a reaction volume. The spectrometer comprises a noninteractive waveguide, a substrate, an entrance grating and an exit grating, an electromagnetic radiation source, and an electromagnetic radiation sensing device. There is further disclosed a chemical sensor to determine the pressure and concentration of a chemical species in a mixture comprising an interactive waveguide, a substrate, an entrance grating and an exit grating, an electromagnetic radiation source, and an electromagnetic radiation sensing device.

  17. Diffuse-light absorption spectroscopy by fiber optics for detecting and quantifying the adulteration of extra virgin olive oil

    NASA Astrophysics Data System (ADS)

    Mignani, A. G.; Ciaccheri, L.; Ottevaere, H.; Thienpont, H.; Conte, L.; Marega, M.; Cichelli, A.; Attilio, C.; Cimato, A.

    2010-09-01

    A fiber optic setup for diffuse-light absorption spectroscopy in the wide 400-1700 nm spectral range is experimented for detecting and quantifying the adulteration of extra virgin olive oil caused by lower-grade olive oils. Absorption measurements provide spectral fingerprints of authentic and adulterated oils. A multivariate processing of spectroscopic data is applied for discriminating the type of adulterant and for predicting its fraction.

  18. Composition Dependence of the Optical Conductivity of NiPt Alloys Determined by Spectroscopic Ellipsometry

    NASA Astrophysics Data System (ADS)

    Abdallah, Lina; Tawalbeh, Tarek; Vasiliev, Igor; Zollner, Stefan; Lavoie, Christian; Ozcan, Ahmet; Raymond, Mark

    2012-10-01

    The complex dielectric function of different Ni-Pt alloys (0% to 25% Pt concentration, 10nm thickness) was determined using spectroscopic ellipsometry over a broad photon energy range from 0.6 to 6.6eV. Data were fitted using basis spline functions as well as Drude-Lorentz oscillators to describe free carrier absorption and interband transitions. We found absorption peaks at 1.5 and 4.7 eV due to interband transitions. Results showed a broadening in the absorption peak of Nickel with increasing the Platinum concentration in the alloy. The experimental results were compared with ab initio density functional theory band structure calculations which showed that adding Platinum enhances the density of states of Nickel especially at low energies. Annealing the metals at 500^o C for 30 s increases the optical conductivity.

  19. Spectroscopic Properties of Neodymium-Doped Yttrium Orthovanadate Single Crystals with High-Resolution Measurement

    NASA Astrophysics Data System (ADS)

    Sato, Yoichi; Taira, Takunori

    2002-10-01

    The absorption and fluorescence spectra of the neodymium-doped yttrium orthovanadate (Nd:YVO4) single crystal were investigated carefully. For the 808.8-nm absorption cross section, the published values varied between 18.4 and 25.6 × 10-20 cm2 for π-polarization. The authors evaluated this spectroscopic parameter with high resolution at 0.5 nm, and discovered 48.4 cm-1 at 808.8 nm even for the absorption of 1 at.% Nd3+-ion-doped YVO4 single crystal. This value is 1.3 times larger than the well-known value, and confirms that Nd:YVO4 is very suitable for microchip lasers, and that certain laser characteristics of Nd:YVO4 of previous works should be re-evaluated.

  20. Influence of silver nanoparticles on the spectroscopic properties of Sm3+ doped boro-phosphate glasses

    NASA Astrophysics Data System (ADS)

    Suthanthirakumar, P.; Marimuthu, K.

    2016-05-01

    The Sm3+ doped novel boro-phosphate glasses containing silver nanoparticles (NPs) (SmBPxA) have been prepared following the melt quenching technique and their structural and spectroscopic behavior were studied through HR-TEM, optical absorption and photoluminescence spectral measurements. The TEM analysis validates the existence of Ag NPs with an average diameter of ~8 nm. The Surface plasmon resonance (SPR) band of silver NPs was found at around 600 nm from the absorption spectrum of the Sm3+ ions free glass sample. The optical band gap energy (Eopt) corresponding to the direct and indirect allowed transitions and the Urbach energy (ΔE) values were determined from the absorption spectral measurements. The luminescence intensity is found to get enhance when the Ag NPs were embedded along with the Sm3+ ions in the prepared glasses due to the local electric field effect around the rare earth (RE) ion site produced by the SPR of Ag NPs.

  1. Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

    NASA Technical Reports Server (NTRS)

    Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

    1995-01-01

    Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric

  2. A SURVEY OF ALKALI LINE ABSORPTION IN EXOPLANETARY ATMOSPHERES

    SciTech Connect

    Jensen, Adam G.; Redfield, Seth; Endl, Michael; Cochran, William D.; Koesterke, Lars; Barman, Travis S. E-mail: sredfield@wesleyan.edu E-mail: wdc@astro.as.utexas.edu E-mail: barman@lowell.edu

    2011-12-20

    We obtained over 90 hr of spectroscopic observations of four exoplanetary systems with the Hobby-Eberly Telescope. Observations were taken in transit and out of transit, and we analyzed the differenced spectra-i.e., the transmission spectra-to inspect it for absorption at the wavelengths of the neutral sodium (Na I) doublet at {lambda}{lambda}5889, 5895 and neutral potassium (K I) at {lambda}7698. We used the transmission spectrum at Ca I {lambda}6122-which shows strong stellar absorption but is not an alkali metal resonance line that we expect to show significant absorption in these atmospheres-as a control line to examine our measurements for systematic errors. We use an empirical Monte Carlo method to quantify these systematic errors. In a reanalysis of the same data set using a reduction and analysis pipeline that was derived independently, we confirm the previously seen Na I absorption in HD 189733b at a level of (- 5.26 {+-} 1.69) Multiplication-Sign 10{sup -4} (the average value over a 12 A integration band to be consistent with previous authors). Additionally, we tentatively confirm the Na I absorption seen in HD 209458b (independently by multiple authors) at a level of (- 2.63 {+-} 0.81) Multiplication-Sign 10{sup -4}, though the interpretation is less clear. Furthermore, we find Na I absorption of (- 3.16 {+-} 2.06) Multiplication-Sign 10{sup -4} at <3{sigma} in HD 149026b; features apparent in the transmission spectrum are consistent with real absorption and indicate this may be a good target for future observations to confirm. No other results (Na I in HD 147506b and Ca I and K I in all four targets) are significant to {>=}3{sigma}, although we observe some features that we argue are primarily artifacts.

  3. Spectroscopic Classifications of Optical Transients with SOAR

    NASA Astrophysics Data System (ADS)

    Hounsell, R. A.; Miller, J. A.; Pan, Y.-C.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.; Smith, K. W.; Wright, D.; Smartt, S. J.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.

    2016-06-01

    We report the following classifications of optical transients from spectroscopic observations with the Goodman spectrograph on the SOAR 4-m telescope. Targets were supplied by the Pan-STARRS Survey for Transients (PSST).

  4. Monitoring spectroscopic binaries in anticipation of Gaia

    NASA Astrophysics Data System (ADS)

    Pourbaix, Dimitri; Halbwachs, Jean-Louis; Arenou, Frederic

    2015-08-01

    For several already known spectroscopic binaries, it is anticipated that Gaia will provide an exquisite astrometric orbit of the photocenter. In case of double-lined spectroscopic binaries, the orbital inclination supplied by Gaia will lead to the mass of both components.. For those masses to be useful, an accuracy of 2-3% is required. This can only be achieved if the spectroscopic orbit is very accurate too. A long term monitoring of good spectroscopic candidates in on going on Sophie at the Observatory of Haute Provence and on Hermes on the Mercator telescope in La Palma. For some of these systems, we have already derived a definitive SB2 orbital solution while, for others, the secondary remains unreachable. We present these new solutions in conjunction with the possible impact on the Hipparcos astrometric solution.

  5. Asiago spectroscopic classification of AT2016bry

    NASA Astrophysics Data System (ADS)

    Ochner, P.; Tinella, V.; Righetti, G. L.; Belligoli, R.; Castellani, F.; Pastorello, A.; Cappellaro, E.; Benetti, S.; Tomasella, L.; Elias-Rosa, N.; Tartaglia, L.; Terreran, G.; Turatto, M.

    2016-05-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of AT2016bry, discovered by V. Tinella in UGC 11635, and preliminary photometric follow-up.

  6. Asiago spectroscopic classification of AT2016ajo

    NASA Astrophysics Data System (ADS)

    Terreran, G.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Ochner, P.; Tartaglia, L.; Tomasella, L.; Turatto, M.

    2016-03-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of AT2016ajo, discovered by Y. Ding, W. Gao and X. Gao in an anonymous galaxy near UGC 11344.

  7. CSP Spectroscopic Classification of LSQ16oi

    NASA Astrophysics Data System (ADS)

    Morrell, N.; Phillips, M.; Lira, P.; Ellman, N.; Baltay, C.; Rabinowitz, D.; Rostami, S.; Hsiao, E. Y.

    2016-02-01

    We report the spectroscopic classification of a La Silla-QUEST (LSQ) supernova (Baltay et al. 2013, PASP, 125, 683) taken using WFCCD on the 2.5-m du Pont Telescope as part of the Carnegie Supernova Project (CSP).

  8. Fast Hadamard Spectroscopic Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Goelman, G.

    1994-07-01

    Fast Hadamard spectroscopic imaging (HSI) techniques are presented. These techniques combine transverse and longitudinal encoding to obtain multiple-volume localization. The fast techniques are optimized for nuclei with short T2 and long T1 relaxation times and are therefore suitable for in vivo31P spectroscopy. When volume coils are used in fast HSI techniques, the signal-to-noise ratio per unit time (SNRT) is equal to the SNRT in regular HSI techniques. When surface coils are used, fast HSI techniques give significant improvement of SNRT over conventional HSI. Several fast techniques which are different in total experimental time and pulse demands are presented. When the number of acquisitions in a single repetition time is not higher than two, fast HSI techniques can be used with surface coils and the B1 inhomogeneity does not affect the localization. Surface-coil experiments on phantoms and on human calf muscles in vivo are presented. In addition, it is shown that the localization obtained by the HSI techniques are independent of the repetition times.

  9. SDSS spectroscopic survey of stars

    SciTech Connect

    Ivezic, Zeljko; Schlegel, D.; Uomoto, A.; Bond, N.; Beers, T.; Allende Prieto, C.; Wilhelm, R.; Lee, Y.Sun; Sivarani, T.; Juric, M.; Lupton, R.; /Washington U., Seattle, Astron. Dept. /LBL, Berkeley /Johns Hopkins U. /Princeton U. /Michigan State U. /Texas U. /Texas Tech. /UC, Santa Cruz /Fermilab /Naval Observ., Flagstaff /Drexel U.

    2007-01-01

    In addition to optical photometry of unprecedented quality, the Sloan Digital Sky Survey (SDSS) is also producing a massive spectroscopic database. They discuss determination of stellar parameters, such as effective temperature, gravity and metallicity from SDSS spectra, describe correlations between kinematics and metallicity, and study their variation as a function of the position in the Galaxy. They show that stellar parameter estimates by Beers et al. show a good correlation with the position of a star in the g-r vs. u-g color-color diagram, thereby demonstrating their robustness as well as a potential for photometric parameter estimation methods. Using Beers et al. parameters, they find that the metallicity distribution of the Milky Way stars at a few kpc from the galactic plane is bimodal with a local minimum at [Z/Z{sub {circle_dot}}] {approx} -1.3. The median metallicity for the low-metallicity [Z/Z{sub {circle_dot}}] < =1.3 subsample is nearly independent of Galactic cylindrical coordinates R and z, while it decreases with z for the high-metallicity [Z/Z{sub {circle_dot}}] > -1.3 sample. they also find that the low-metallicity sample has {approx} 2.5 times larger velocity dispersion and that it does not rotate (at the {approx} 10 km/s level), while the rotational velocity of the high-metallicity sample decreases smoothly with the height above the galactic plane.

  10. SDSS spectroscopic survey of stars.

    NASA Astrophysics Data System (ADS)

    Ivezić, Ž.; Schlegel, D.; Uomoto, A.; Bond, N.; Beers, T.; Allende Prieto, C.; Wilhelm, R.; Lee, Y. Sun; Sivarani, T.; Jurić, M.; Lupton, R.; Rockosi, C.; Knapp, G.; Gunn, J.; Yanny, B.; Jester, S.; Kent, S.; Pier, J.; Munn, J.; Richards, G.; Newberg, H.; Blanton, M.; Eisenstein, D.; Hawley, S.; Anderson, S.; Harris, H.; Kiuchi, F.; Chen, A.; Bushong, J.; Sohi, H.; Haggard, D.; Kimball, A.; Barentine, J.; Brewington, H.; Harvanek, M.; Kleinman, S.; Krzesinski, J.; Long, D.; Nitta, A.; Snedden, S.; SDSS Collaboration

    In addition to optical photometry of unprecedented quality, the Sloan Digital Sky Survey (SDSS) is also producing a massive spectroscopic database. We discuss determination of stellar parameters, such as effective temperature, gravity and metallicity from SDSS spectra, describe correlations between kinematics and metallicity, and study their variation as a function of the position in the Galaxy. We show that stellar parameter estimates by Beers et al. show a good correlation with the position of a star in the g-r vs. u-g color-color diagram, thereby demonstrating their robustness as well as a potential for photometric parameter estimation methods. Using Beers et al. parameters, we find that the metallicity distribution of the Milky Way stars at a few kpc from the galactic plane is bimodal with a local minimum at [Z/Z_⊙] ˜ -1.3. The median metallicity for the low-metallicity [Z/Z_⊙]< -1.3 subsample is nearly independent of Galactic cylindrical coordinates R and z, while it decreases with z for the high-metallicity [Z/Z_⊙]> -1.3 sample. We also find that the low-metallicity sample has ˜2.5 times larger velocity dispersion and that it does not rotate (at the ˜10 km/s level), while the rotational velocity of the high-metallicity sample decreases smoothly with the height above the galactic plane.

  11. Vibrational spectroscopic characterization of fluoroquinolones

    NASA Astrophysics Data System (ADS)

    Neugebauer, U.; Szeghalmi, A.; Schmitt, M.; Kiefer, W.; Popp, J.; Holzgrabe, U.

    2005-05-01

    Quinolones are important gyrase inhibitors. Even though they are used as active agents in many antibiotics, the detailed mechanism of action on a molecular level is so far not known. It is of greatest interest to shed light on this drug-target interaction to provide useful information in the fight against growing resistances and obtain new insights for the development of new powerful drugs. To reach this goal, on a first step it is essential to understand the structural characteristics of the drugs and the effects that are caused by the environment in detail. In this work we report on Raman spectroscopical investigations of a variety of gyrase inhibitors (nalidixic acid, oxolinic acid, cinoxacin, flumequine, norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, enoxacin, sarafloxacin and moxifloxacin) by means of micro-Raman spectroscopy excited with various excitation wavelengths, both in the off-resonance region (532, 633, 830 and 1064 nm) and in the resonance region (resonance Raman spectroscopy at 244, 257 and 275 nm). Furthermore DFT calculations were performed to assign the vibrational modes, as well as for an identification of intramolecular hydrogen bonding motifs. The effect of small changes in the drug environment was studied by adding successively small amounts of water until physiological low concentrations of the drugs in aqueous solution were obtained. At these low concentrations resonance Raman spectroscopy proved to be a useful and sensitive technique. Supplementary information was obtained from IR and UV/vis spectroscopy.

  12. Spectroscopic characterization of visbreaking tars

    SciTech Connect

    Scotti, R.; Clericuzio, M.; Pirovano, C.

    1995-12-31

    Visbreaking (VB) is a thermal cracking process, widely used in the refineries of Western Europe to obtain distillates (gasoil, naphtha) from a petroleum residue (feedstock). The visbroken residue (tar) is used to produce fuel oil, after addition of the appropriate amounts of cutter-stock. Even if the highest conversion of feedstock would be desirable, the severity of the VB process is limited by the stability of the resulting VB tars. The stability index (SI) here employed is: SI = I + V{sub cet}, where V{sub cet} is the maximum amount of n-cetane, expressed as ml of cetane for g of sample, that can be added before the flocculation of asphaltenes starts. VB tars having SI<1.1 are considered to be unstable and cannot be used in the preparation of fuel oils with the appropriate specifications. Several papers can be found in the literature dealing with the molecular changes occuring during the VB process. The present paper is aimed at verifying the amount of information that can be extracted from optical spectroscopies and, in particular, the possibility of directly monitoring the physico-chemical modifications caused by VB process. To this purpose a series of VB tars, produced from a single feedstock at different severities, were investigated by a number of spectroscopic techniques, viz.: NIR; UV-Vis; Fluorescence; {sup 1}H and {sup 13}C NUR, EPR.

  13. Scattering with absorptive interaction

    NASA Astrophysics Data System (ADS)

    Cassing, W.; Stingl, M.; Weiguny, A.

    1982-07-01

    The S matrix for a wide class of complex and nonlocal potentials is studied, with special attention given to the motion of singularities in the complex k plane as a function of the imaginary coupling strength. Modifications of Levinson's theorem are obtained and discussed. Analytic approximations to the S matrix in the vicinity of narrow resonances are exhibited and compared to numerical results of resonating-group calculations. The problem of defining resonances in the case of complex interactions is discussed, making contact with the usual analysis of scattering in terms of Argand diagrams. NUCLEAR REACTIONS Scattering theory, S matrix for absorptive potentials.

  14. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  15. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  16. Handbook of Basic Atomic Spectroscopic Data

    National Institute of Standards and Technology Data Gateway

    SRD 108 Handbook of Basic Atomic Spectroscopic Data (Web, free access)   This handbook provides a selection of the most important and frequently used atomic spectroscopic data. The compilation includes data for the neutral and singly-ionized atoms of all elements hydrogen through einsteinium (Z = 1-99). The wavelengths, intensities, and spectrum assignments are given for each element, and the data for the approximately 12,000 lines of all elements are also collected into a single table.

  17. Neutron spectroscopic factors of Ar34 and Ar46 from (p,d) transfer reactions

    NASA Astrophysics Data System (ADS)

    Lee, Jenny; Tsang, M. B.; Bazin, D.; Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Lynch, W. G.; Rogers, A. M.; Sanetullaev, A.; Sun, Z. Y.; Youngs, M.; Charity, R. J.; Sobotka, L. G.; Famiano, M.; Hudan, S.; Shapira, D.; O'Malley, P.; Peters, W. A.; Chae, K. Y.; Schmitt, K.

    2011-01-01

    Single-neutron-transfer measurements using (p,d) reactions have been performed at 33 MeV per nucleon with proton-rich Ar34 and neutron-rich Ar46 beams in inverse kinematics. The extracted spectroscopic factors are compared to the large-basis shell-model calculations. Relatively weak quenching of the spectroscopic factors is observed between Ar34 and Ar46. The experimental results suggest that neutron correlations have a weak dependence on the asymmetry of the nucleus over this isotopic region. The present results are consistent with the systematics established from extensive studies of spectroscopic factors and dispersive optical-model analyses of Ca40-49 isotopes. They are, however, inconsistent with the trends obtained in knockout-reaction measurements.

  18. Shedding light on the photostability of two intermolecular charge-transfer complexes between highly fluorescent bis-1,8-naphthalimide dyes and some π-acceptors: A spectroscopic study in solution and solid states

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Ismail, Lamia A.; Adam, Abdel Majid A.

    2015-01-01

    Given the great importance of the various uses of 1,8-naphthalimides in the trends of biology, medicine and industry, the current study focused on extending the scope of these dyes by introducing some of their charge-transfer (CT) complexes. For this purpose, two highly fluorescent bis-1,8-naphthalimide dyes and their complexes with some π-acceptors have been synthesized and characterized spectroscopically. The π-acceptors include picric acid (PA), chloranilic acid (CLA), tetracyanoquinodimethane (TCNQ) and dichlorodicyanobenzoquinone (DDQ). The molecular structure, spectroscopic and fluorescence properties as well as the binding modes were deduced from IR, UV-vis and 1H NMR spectral studies. The binding ratio of complexation was determined to be 1:1 according to the elemental analyses and photometric titrations. It has been found that the order of acceptance ability for the different acceptors is TCNQ > DDQ > CLA > PA. The photostability of 1,8-naphthalimide dye as a donor and its charge-transfer complex doped in polymethyl methacrylate/PMMA were exposed to UV-Vis radiation and the change in the absorption spectra was achieved at different times during irradiation period.

  19. Shedding light on the photostability of two intermolecular charge-transfer complexes between highly fluorescent bis-1,8-naphthalimide dyes and some π-acceptors: a spectroscopic study in solution and solid states.

    PubMed

    Refat, Moamen S; Ismail, Lamia A; Adam, Abdel Majid A

    2015-01-01

    Given the great importance of the various uses of 1,8-naphthalimides in the trends of biology, medicine and industry, the current study focused on extending the scope of these dyes by introducing some of their charge-transfer (CT) complexes. For this purpose, two highly fluorescent bis-1,8-naphthalimide dyes and their complexes with some π-acceptors have been synthesized and characterized spectroscopically. The π-acceptors include picric acid (PA), chloranilic acid (CLA), tetracyanoquinodimethane (TCNQ) and dichlorodicyanobenzoquinone (DDQ). The molecular structure, spectroscopic and fluorescence properties as well as the binding modes were deduced from IR, UV-vis and (1)H NMR spectral studies. The binding ratio of complexation was determined to be 1:1 according to the elemental analyses and photometric titrations. It has been found that the order of acceptance ability for the different acceptors is TCNQ>DDQ>CLA>PA. The photostability of 1,8-naphthalimide dye as a donor and its charge-transfer complex doped in polymethyl methacrylate/PMMA were exposed to UV-Vis radiation and the change in the absorption spectra was achieved at different times during irradiation period. PMID:25022501

  20. SNS shielding analyses overview

    SciTech Connect

    Popova, Irina; Gallmeier, Franz; Iverson, Erik B; Lu, Wei; Remec, Igor

    2015-01-01

    This paper gives an overview on on-going shielding analyses for Spallation Neutron Source. Presently, the most of the shielding work is concentrated on the beam lines and instrument enclosures to prepare for commissioning, save operation and adequate radiation background in the future. There is on-going work for the accelerator facility. This includes radiation-protection analyses for radiation monitors placement, designing shielding for additional facilities to test accelerator structures, redesigning some parts of the facility, and designing test facilities to the main accelerator structure for component testing. Neutronics analyses are required as well to support spent structure management, including waste characterisation analyses, choice of proper transport/storage package and shielding enhancement for the package if required.

  1. The HI absorption "Zoo"

    NASA Astrophysics Data System (ADS)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1absorption (FW20) lies in the range 63 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1

  2. HHFW power absorption in NBI target plasmas

    NASA Astrophysics Data System (ADS)

    Leblanc, B. P.; Bell, R. E.; Hosea, J. C.; Phillips, C. K.; Podesta, M.; Roquemore, A. L.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Berk, L.; Bonoli, P. T.; Harvey, R. W.; Ryan, P. M.

    2010-11-01

    Experimental and analytic work is ongoing to ascertain the efficiency of using high-harmonic fast waves (HHFW) to inject auxiliary power into NBI heated NSTX plasmas. As a result of progress in understanding edge effects relevant for wave coupling, HHFW power is routinely deposited within the last closed flux surface . Increases of the plasma stored energy, the electron temperature and the neutron production rate are observed when HHFW power is applied. Two mechanisms compete for the absorption of the HHFW reaching the main plasma: (1) electron heating via Landau damping and transit-time magnetic pumping; (2) rf acceleration of NBI generated fast ions. The power absorption will be investigated by comparing the experimental data with analyses and predictions from the TRANSP/TORIC, GENRAY and CQL3D codes. This work is supported by DOE contract DE-AC02-09CH11466.

  3. Graphite filter atomizer in atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Katskov, Dmitri A.

    2007-09-01

    Graphite filter atomizers (GFA) for electrothermal atomic absorption spectrometry (ETAAS) show substantial advantages over commonly employed electrothermal vaporizers and atomizers, tube and platform furnaces, for direct determination of high and medium volatility elements in matrices associated with strong spectral and chemical interferences. Two factors provide lower limits of detection and shorter determination cycles with the GFA: the vaporization area in the GFA is separated from the absorption volume by a porous graphite partition; the sample is distributed over a large surface of a collector in the vaporization area. These factors convert the GFA into an efficient chemical reactor. The research concerning the GFA concept, technique and analytical methodology, carried out mainly in the author's laboratory in Russia and South Africa, is reviewed. Examples of analytical applications of the GFA in AAS for analysis of organic liquids and slurries, bio-samples and food products are given. Future prospects for the GFA are discussed in connection with analyses by fast multi-element AAS.

  4. Spectral Fingerprinting of Individual Cells Visualized by Cavity-Reflection-Enhanced Light-Absorption Microscopy

    PubMed Central

    Arai, Yoshiyuki; Yamamoto, Takayuki; Minamikawa, Takeo; Takamatsu, Tetsuro; Nagai, Takeharu

    2015-01-01

    The absorption spectrum of light is known to be a “molecular fingerprint” that enables analysis of the molecular type and its amount. It would be useful to measure the absorption spectrum in single cell in order to investigate the cellular status. However, cells are too thin for their absorption spectrum to be measured. In this study, we developed an optical-cavity-enhanced absorption spectroscopic microscopy method for two-dimensional absorption imaging. The light absorption is enhanced by an optical cavity system, which allows the detection of the absorption spectrum with samples having an optical path length as small as 10 μm, at a subcellular spatial resolution. Principal component analysis of various types of cultured mammalian cells indicates absorption-based cellular diversity. Interestingly, this diversity is observed among not only different species but also identical cell types. Furthermore, this microscopy technique allows us to observe frozen sections of tissue samples without any staining and is capable of label-free biopsy. Thus, our microscopy method opens the door for imaging the absorption spectra of biological samples and thereby detecting the individuality of cells. PMID:25950513

  5. A spectroscopic census in young stellar regions: the σ Orionis cluster

    SciTech Connect

    Hernández, Jesús; Perez, Alice; Hernan, Ramírez; Calvet, Nuria; Hartmann, Lee; Briceño, Cesar; Olguin, Lorenzo; Contreras, Maria E.; Allen, Lori; Espaillat, Catherine

    2014-10-10

    We present a spectroscopic survey of the stellar population of the σ Orionis cluster. We have obtained spectral types for 340 stars. Spectroscopic data for spectral typing come from several spectrographs with similar spectroscopic coverage and resolution. More than half of the stars in our sample are members confirmed by the presence of lithium in absorption, strong Hα in emission or weak gravity-sensitive features. In addition, we have obtained high-resolution (R ∼ 34,000) spectra in the Hα region for 169 stars in the region. Radial velocities were calculated from this data set. The radial velocity distribution for members of the cluster is in agreement with previous work. Analysis of the profile of the Hα line and infrared observations reveals two binary systems or fast rotators that mimic the Hα width expected in stars with accretion disks. On the other hand, there are stars with optically thick disks and narrow Hα profiles not expected in stars with accretion disks. This contribution constitutes the largest homogeneous spectroscopic data set of the σ Orionis cluster to date.

  6. Spectroscopic investigation of protein corona

    NASA Astrophysics Data System (ADS)

    Choudhary, Poonam

    Nanotechnology has revolutionalized the landscape of modern science and technology, including materials, electronics, therapeutics, bioimaging, sensing, and the environment. Research in the past decade has examined the fate of nanomaterials in vitro and in vivo, as well as the interactions between nanoparticles and biological and ecosystems using primarily toxicological and ecotoxicological approaches. However, due to the versatility in the physical and physicochemical properties of nanoparticles, and due to the vast complexity of their hosting systems, the solubility, transformation, and biocompatibility of nanomaterials are still poorly understood. Nanotechnology has been undergoing tremendous development in recent decades, driven by realized perceived applications of nanomaterials in electronics, therapeutics, imaging, sensing, environmental remediation, and consumer products. Nanoparticles on entering the blood stream undergo an identity change, they become coated with proteins. There are different kind of proteins present in blood. Proteins compete for getting coated over the surface of nanoparticle and this whole entity of proteins coated over nanoparticle surface is called Protein Corona. Proteins tightly bound to the surface of nanoparticle form hard corona and the ones loosely bound on the outer surface form soft corona. This dissertation is aimed at spectroscopic investigation of Protein Corona. Chapter I of this dissertation offers a comprehensive review of the literature based on nanomaterials with the focus on carbon based nanomaterilas and introduction to Protein Corona. Chapter II is based different methods used for Graphene Synthesis,different types of defects and doping. In Chapter III influence of defects on Graphene Protein Corona was investigated. Chapter IV is based on the study of Apoptosis induced cell death by Gold and silver nanoparticles. In vitro study of effect of Protein Corona on toxicity of cells was done.

  7. Differential optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S. (Inventor)

    1978-01-01

    A differential optoacoustic absorption detector employed two tapered cells in tandem or in parallel. When operated in tandem, two mirrors were used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell was tapered to conform to the shape of the beam so that the volume of one was the same as for the other, and the volume of each received maximum illumination. The axes of the cells were placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employed a beam splitter and two lenses to operate the cells in parallel.

  8. Cloud absorption radiometer

    NASA Technical Reports Server (NTRS)

    Strange, M. G.

    1988-01-01

    The Cloud Absorption Radiometer (CAR) was developed to measure spectrally how light is scattered by clouds and to determine the single scattering albedo, important to meteorology and climate studies, with unprecedented accuracy. This measurement is based on ratios of downwelling to upwelling radiation within clouds, and so is not strongly dependent upon absolute radiometric calibration of the instrument. The CAR has a 5-inch aperture and 1 degree IFOV, and spatially scans in a plane orthogonal to the flight vector from the zenith to nadir at 1.7 revolutions per second. Incoming light is measured in 13 spectral bands, using silicon, germanium, and indium-antimonide detectors. Data from each channel is digitally recorded in flight with 10-bit (0.1 percent) resolution. The instrument incorporates several novel features. These features are briefly detailed.

  9. Optical and spectroscopic properties of soda lime alumino-silicate glasses doped with erbium and silver

    NASA Astrophysics Data System (ADS)

    Carmo, A. P.; Bell, M. J. V.; Da Costa, Z. M.; Anjos, V.; Barbosa, L. C.; Chillcce, E. F.; Giehl, J. M.; Pontuschka, W. M.

    2011-10-01

    Spectroscopic properties of Ag/Er co-doped soda lime silicate glasses have been studied with the aim of assessing the effective role of silver as a sensitizer for erbium. Changes in spectroscopic properties of Er 3+ as a function of silver addition to the base composition have been measured. Transmission electron microscopy (TEM), absorption as well as photoluminescence measurements in the visible and infrared spectral region, particularly 4I 13/2 → 4I 15/2 transition of the Er 3+ ion were performed; excitation wavelengths in the range from 325 to 808 nm were used. Enhancement of the Er 3+ luminescence at 1.54 μm was observed when Ag was added.

  10. Spectroscopic Challenges in the Modelling and Diagnostics of High Temperature Air Plasma Radiation for Aerospace Applications

    SciTech Connect

    Laux, Christophe O.

    2007-04-06

    State-of-the-art spectroscopic models of the radiative transitions of interest for Earth re-entry and ground-based diagnostic facilities for aerospace applications are reviewed. The spectral range considered extends from the vacuum ultraviolet to the mid-infrared range (80 nm to 5.5 {mu}m). The modeling results are compared with absolute intensity measurements of the ultraviolet-visible-infrared emission of a well-characterized high-temperature air plasma produced with a 50 kW inductively coupled radio-frequency plasma torch, and with high-resolution absorption spectra from the Center for Astrophysics in the vacuum ultraviolet. The Spectroscopic data required to better model the spectral features of interest for aerospace applications are discussed.

  11. Measurement of the dielectric function spectra of low dielectric constant using the spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Horie, Masahiro; Postava, Kamil; Yamaguchi, Tomuo; Akashika, Kumiko; Hayashi, Hideki; Kitamura, Fujikazu

    2003-05-01

    The dielectric function spectra of low dielectric constants (low-k) materials have been determined using spectroscopic ellipsometry, normal incidence spectroscopic reflectometry, and Fourier transform infrared transmission spectrometry over a wide spectral range from 0.03 to 5.4 eV (230nm to 40.5um wavelength region). The electric and ionic contributions to the overall static dielectric constants were determined for representative materials used in the semiconductor industry for interlayer dielectrics: (1) FLARE - organic spin-on polymer, (2) HOSP - spin-on hybrid organic-siloxane polymer from the Honeywell Electric Materials Company, and (3) SiLK- organic dielectric resin from the Dow Chemical Company. The main contributions to the static dielectric constant of the low-k materials studied were found to be the electric and ionic absorption.

  12. Experimental and theoretical spectroscopic studies of dye modification in synthetic Maya Blue pigment

    NASA Astrophysics Data System (ADS)

    Reza, Layra; Manciu, Felicia; Ramirez, Alejandra; Chianelli, Russell

    2009-03-01

    Maya pigments are hybrid organic/inorganic materials with multiple technology applications that possess unprecedented stability with respect to harsh environment conditions. In this investigation, we address the question of how the organic indigo dye modifies as it binds to the inorganic palygorskite clay to form a pigment similar to Maya Blue after a heating treatment is applied. Both infrared and Raman spectroscopic data demonstrate the disappearance of nitrogen-hydrogen (N-H) bonding, as the indigo molecule incorporates into the inorganic palygorskite material. This effect suggests a transformation of the dye from indigo to dehydroindigo. Furthermore, the Raman and infrared absorption results demonstrate partial elimination of the selection rules for the centrosymmetric indigo, which provides further evidence for this conversion. Theoretical spectroscopic studies are also addressed in this investigation to confirm the transformation of the dye into dehydroindigo.

  13. Percutaneous absorption in preterm infants.

    PubMed

    West, D P; Halket, J M; Harvey, D R; Hadgraft, J; Solomon, L M; Harper, J I

    1987-11-01

    The skin of preterm infants varies considerably in its level of maturity. To understand skin absorption in premature infants better, we report a technique for the assessment of percutaneous absorption at various gestational and postnatal ages using stable, isotope-labeled (13C6) benzoic acid. Our results indicate that in the preterm infant, this method detects enhanced skin absorption in the first postnatal days, which declines over three weeks to that expected of a full-term infant. This approach also indicates an inverse relationship between gestational age and skin absorption, as well as postnatal age and skin absorption. The reported technique is a safe and noninvasive method using a model skin penetrant for the study of percutaneous absorption in preterm infants from which basic data may be derived to add to our understanding of skin barrier function. PMID:3422856

  14. Absorption of isoflurane by silica gel.

    PubMed

    Lumb, A B; Landon, M J

    1991-07-01

    We have studied the capacity of the drying agent silica gel (SG) to absorb isoflurane from gas samples. When dry, SG was able to absorb 31 times its own volume of isoflurane vapour, which could be recovered almost completely from the SG by displacement with water vapour. However, we were unable to demonstrate any significant absorption of isoflurane by wet SG. Care must be taken, therefore, when using SG as a drying agent in the sampling line of an analyser during research involving volatile anaesthetic agents. PMID:1650238

  15. Determination of spectroscopic properties of atmospheric molecules from high resolution vacuum ultraviolet cross section and wavelength measurements

    NASA Technical Reports Server (NTRS)

    Parkinson, W. H.; Yoshino, K.; Freeman, D. E.

    1988-01-01

    Progress is given on work on: cross section measurements in the transmission window regions of the Schumann-Runge bands of oxygen; the determinations of predissociation linewidths; the theoretical calculation of band oscillator strengths of the Schumann-Runge absorption bands of O-16O-18; the determination of molecular spectroscopic constants; and the combined Herzberg continuum cross sections. The experimental investigations relevant to the cross section measurements, predissociation linewidths, and molecular spectroscopic constants are effected at high resolution with a 6.65 m scanning spectrometer which is, by virtue of its small instrumental width (FWHM = 0.0013 nm), suitable for cross section measurements of molecular bands with discrete rotational structure. Such measurements are needed for accurate calculations of the stratospheric production of atomic oxygen and heavy ozone formed following the photo-predissociation of O-16O-18 by solar radiation penetrating between the absorption lines of O-16(sub 2).

  16. Spacelab Charcoal Analyses

    NASA Technical Reports Server (NTRS)

    Slivon, L. E.; Hernon-Kenny, L. A.; Katona, V. R.; Dejarme, L. E.

    1995-01-01

    This report describes analytical methods and results obtained from chemical analysis of 31 charcoal samples in five sets. Each set was obtained from a single scrubber used to filter ambient air on board a Spacelab mission. Analysis of the charcoal samples was conducted by thermal desorption followed by gas chromatography/mass spectrometry (GC/MS). All samples were analyzed using identical methods. The method used for these analyses was able to detect compounds independent of their polarity or volatility. In addition to the charcoal samples, analyses of three Environmental Control and Life Support System (ECLSS) water samples were conducted specifically for trimethylamine.

  17. Calculation of equilibrium constants from multiwavelength spectroscopic data--II: SPECFIT: two user-friendly programs in basic and standard FORTRAN 77.

    PubMed

    Gampp, H; Maeder, M; Meyer, C J; Zuberbühler, A D

    1985-04-01

    A new program (SPECFIT), written in HP BASIC or FORTRAN 77, for the calculation of stability constants from spectroscopic data, is presented. Stability constants have been successfully calculated from multiwavelength spectrophotometric and EPR data, but the program can be equally well applied to the numerical treatment of other spectroscopic measurements. The special features included in SPECFIT to improve convergence, increase numerical reliability, and minimize memory as well as computing time requirements, include (i) elimination of the linear parameters (i.e., molar absorptivities), (ii) the use of analytical instead of numerical derivatives and (iii) factor analysis. Calculation of stability constants from spectroscopic data is then as straightforward as from potentiometric titration curves and gives results of analogous reproducibility. The spectroscopic method has proved, however, to be superior in discrimination between chemical models. PMID:18963840

  18. sick: The Spectroscopic Inference Crank

    NASA Astrophysics Data System (ADS)

    Casey, Andrew R.

    2016-03-01

    There exists an inordinate amount of spectral data in both public and private astronomical archives that remain severely under-utilized. The lack of reliable open-source tools for analyzing large volumes of spectra contributes to this situation, which is poised to worsen as large surveys successively release orders of magnitude more spectra. In this article I introduce sick, the spectroscopic inference crank, a flexible and fast Bayesian tool for inferring astrophysical parameters from spectra. sick is agnostic to the wavelength coverage, resolving power, or general data format, allowing any user to easily construct a generative model for their data, regardless of its source. sick can be used to provide a nearest-neighbor estimate of model parameters, a numerically optimized point estimate, or full Markov Chain Monte Carlo sampling of the posterior probability distributions. This generality empowers any astronomer to capitalize on the plethora of published synthetic and observed spectra, and make precise inferences for a host of astrophysical (and nuisance) quantities. Model intensities can be reliably approximated from existing grids of synthetic or observed spectra using linear multi-dimensional interpolation, or a Cannon-based model. Additional phenomena that transform the data (e.g., redshift, rotational broadening, continuum, spectral resolution) are incorporated as free parameters and can be marginalized away. Outlier pixels (e.g., cosmic rays or poorly modeled regimes) can be treated with a Gaussian mixture model, and a noise model is included to account for systematically underestimated variance. Combining these phenomena into a scalar-justified, quantitative model permits precise inferences with credible uncertainties on noisy data. I describe the common model features, the implementation details, and the default behavior, which is balanced to be suitable for most astronomical applications. Using a forward model on low-resolution, high signal

  19. Pick and Choose the Spectroscopic Method to Calibrate the Local Electric Field inside Proteins.

    PubMed

    Haldar, Tapas; Kashid, Somnath M; Deb, Pranab; Kesh, Sandeep; Bagchi, Sayan

    2016-07-01

    Electrostatic interactions in proteins play a crucial role in determining the structure-function relation in biomolecules. In recent years, fluorescent probes have been extensively employed to interrogate the polarity in biological cavities through dielectric constants or semiempirical polarity scales. A choice of multiple spectroscopic methods, not limited by fluorophores, along with a molecular level description of electrostatics involving solute-solvent interactions, would allow more flexibility to pick and choose the experimental technique to determine the local electrostatics within protein interiors. In this work we report that ultraviolet/visible-absorption, infrared-absorption, or (13)C NMR can be used to calibrate the local electric field in both hydrogen bonded and non-hydrogen bonded protein environments. The local electric field at the binding site of a serum protein has been determined using the absorption wavelength as well as the carbonyl stretching frequency of its natural steroid substrate, testosterone. Excellent agreement is observed in the results obtained from two independent spectroscopic techniques. PMID:27295386

  20. Spectroscopic studies of drugs used in the treatment of malignant tumors in ophthalmology

    NASA Astrophysics Data System (ADS)

    Pascu, Mihail-Lucian; Carstocea, Benone D.; Staicu, Angela; Ionita, Marcel A.; Truica, Sorina; Pascu, Ruxandra

    2001-10-01

    Two classes of substances which may be used in the treatment of malignant tumors in ophthalmology are studied from the point of view of their spectroscopic properties: synthetic porphyrines such as TNP, TPP, TSPP and Zn-TSPP and cytostatics such as 5-fluorouracil. The absorption, excitation and fluorescence spectra of the porphyrins are measured in water and DMSO solutions to allow their efficient use in photodynamic therapy studies at irradiation with UV-laser light. A spectroscopic study of 5-fluorouracyl, a cytostatic drug used in the treatment of ophthalmologic tumors is reported. Absorption, fluorescence excitation/emission spectra were measured for solutions of 5-fluorouracyl at 5 X 10-5 M concentration. The effects of UV-VIS irradiation of on the 5-fluorouracyl solutions were investigated. The irradiation was performed with a classical Xe lamp having a power density of 11 mW/cm2, at time intervals between 15 min and 60 min. While the absorption is not affected by light irradiation, the fluorescence of the solutions is increasing with the irradiation duration.

  1. Spectroscopic and Structural Investigations of alpha-beta-, and gamma-AIH3 Phases

    SciTech Connect

    Manciu, F.S.; Graetz, J.; Reza, L.; Durrer, W.G.; Bronson, A.; Lacina, D.

    2010-07-01

    With its reputation as a high-energy density fuel, aluminum hydride (AlH{sub 3}) has received renewed attention as a material that is particularly suitable, not only for hydrogen storage but also for rocket propulsion. While the various phases of AlH{sub 3} have been investigated theoretically, there is a shortage of experimental studies corroborating the theoretical findings. In response to this, we present here an investigation of these compounds based primarily on two research areas in which there is the greatest scarcity of information in the literature, namely Raman and infrared (IR) absorption analysis. To the authors knowledge, this is the first report of experimental far-IR absorption results on these compounds. Two different samples prepared by broadly similar ethereal reactions of AlCl{sub 3} with LiAlH{sub 4} were analyzed. Both Raman and IR absorption measurements indicate that one sample is purely {gamma}-AlH{sub 3} and that the other is a mixture of {alpha}-, {beta}-, and {gamma}-AlH{sub 3} phases. X-ray diffraction confirms the spectroscopic findings, most notably for the {beta}-AlH{sub 3} phase, for which optical spectroscopic data are reported here for the first time.

  2. Multivariate statistical mapping of spectroscopic imaging data.

    PubMed

    Young, Karl; Govind, Varan; Sharma, Khema; Studholme, Colin; Maudsley, Andrew A; Schuff, Norbert

    2010-01-01

    For magnetic resonance spectroscopic imaging studies of the brain, it is important to measure the distribution of metabolites in a regionally unbiased way; that is, without restrictions to a priori defined regions of interest. Since magnetic resonance spectroscopic imaging provides measures of multiple metabolites simultaneously at each voxel, there is furthermore great interest in utilizing the multidimensional nature of magnetic resonance spectroscopic imaging for gains in statistical power. Voxelwise multivariate statistical mapping is expected to address both of these issues, but it has not been previously employed for spectroscopic imaging (SI) studies of brain. The aims of this study were to (1) develop and validate multivariate voxel-based statistical mapping for magnetic resonance spectroscopic imaging and (2) demonstrate that multivariate tests can be more powerful than univariate tests in identifying patterns of altered brain metabolism. Specifically, we compared multivariate to univariate tests in identifying known regional patterns in simulated data and regional patterns of metabolite alterations due to amyotrophic lateral sclerosis, a devastating brain disease of the motor neurons. PMID:19953514

  3. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  4. X-ray Absorption Spectroscopy

    SciTech Connect

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  5. Massive Young Stellar Objects in the Galactic Center. 1; Spectroscopic Identification from Spitzer/IRS Observations

    NASA Technical Reports Server (NTRS)

    An, Deokkeun; Ramirez, Solange V.; Sellgren, Kris; Arendt, Richard G.; Boogert, A. C. Adwin; Robitaille, Thomas P.; Schultheis, Mathias; Cotera, Angela S.; Smith, Howard A.; Stolovy, Susan R.

    2011-01-01

    We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic Center (GC). Our sample of 107 YSO candidates was selected based on IRAC colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone (CMZ), which spans the central approximately 300 pc region of the Milky Way Galaxy. We obtained IRS spectra over 5 micron to 35 micron using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4 micron shoulder on the absorption profile of 15 micron CO2 ice, suggestive of CO2 ice mixed with CH30H ice on grains. This 15.4 micron shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that 9 massive YSOs also reveal molecular gas-phase absorption from C02, C2H2, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8 - 23 solar Mass, which generally agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of approximately 0.07 solar mass/yr at the GC.

  6. MASSIVE YOUNG STELLAR OBJECTS IN THE GALACTIC CENTER. I. SPECTROSCOPIC IDENTIFICATION FROM SPITZER INFRARED SPECTROGRAPH OBSERVATIONS

    SciTech Connect

    An, Deokkeun; RamIrez, Solange V.; Boogert, A. C. Adwin; Sellgren, Kris; Arendt, Richard G.; Schultheis, Mathias; Cotera, Angela S.; Stolovy, Susan R.

    2011-08-01

    We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic center (GC). Our sample of 107 YSO candidates was selected based on Infrared Array Camera (IRAC) colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone, which spans the central {approx}300 pc region of the Milky Way. We obtained IRS spectra over 5-35 {mu}m using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4 {mu}m shoulder on the absorption profile of 15 {mu}m CO{sub 2} ice, suggestive of CO{sub 2} ice mixed with CH{sub 3}OH ice on grains. This 15.4 {mu}m shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that nine massive YSOs also reveal molecular gas-phase absorption from CO{sub 2}, C{sub 2}H{sub 2}, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8-23 M{sub sun}, which generally agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of {approx}0.07 M{sub sun} yr{sup -1} at the GC.

  7. Chemical detection and laser wavelength stabilization employing spectroscopic absorption via laser compliance voltage sensing

    DOEpatents

    Taubman, Matthew S; Phillips, Mark C

    2014-03-18

    Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

  8. X-ray Absorption Spectroscopic Quantification and Speciation Modeling of Sulfate Adsorption on Ferrihydrite Surfaces.

    PubMed

    Gu, Chunhao; Wang, Zimeng; Kubicki, James D; Wang, Xiaoming; Zhu, Mengqiang

    2016-08-01

    Sulfate adsorption on mineral surfaces is an important environmental chemical process, but the structures and respective contribution of different adsorption complexes under various environmental conditions are unclear. By combining sulfur K-edge XANES and EXAFS spectroscopy, quantum chemical calculations, and surface complexation modeling (SCM), we have shown that sulfate forms both outer-sphere complexes and bidentate-binuclear inner-sphere complexes on ferrihydrite surfaces. The relative fractions of the complexes vary with pH, ionic strength (I), and sample hydration degree (wet versus air-dried), but their structures remained the same. The inner-sphere complex adsorption loading decreases with increasing pH while remaining unchanged with I. At both I = 0.02 and 0.1 M, the outer-sphere complex loading reaches maximum at pH ∼5 and then decreases with pH, whereas it monotonically decreases with pH at I = 0.5 M. These observations result from a combination of the ionic-strength effect, the pH dependence of anion adsorption, and the competition between inner- and outer-sphere complexation. Air-drying drastically converts the outer-sphere complexes to the inner-sphere complexes. The respective contributions to the overall adsorption loading of the two complexes were directly modeled with the extended triple layer SCM by implementing the bidentate-binuclear inner-sphere complexation identified in the present study. These findings improve our understanding of sulfate adsorption and its effects on other environmental chemical processes and have important implications for generalizing the adsorption behavior of anions forming both inner- and outer-sphere complexes on mineral surfaces. PMID:27377619

  9. Chemical detection and laser wavelength stabilization employing spectroscopic absorption via laser compliance voltage sensing

    DOEpatents

    Taubman, Matthew S.; Phillips, Mark C.

    2016-01-12

    Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

  10. X-ray absorption spectroscopic studies on novel microporous copper containing catalytic systems

    NASA Astrophysics Data System (ADS)

    Bhargava, Suresh K.; Akolekar, Deepak B.; Foran, Garry

    2006-11-01

    Novel copper metal modified microporous aluminosilicate and aluminophosphate catalysts with the high phase purity were synthesized and characterized. CuK-edge XAS measurements were carried out over a series of copper containing SAPO-34 and ZSM-5 catalysts. EXAFS technique was used to obtain specific climacteric information related to the copper atomic distances, coordination and near neighbour environments. EXAFS studies indicated the presence of different of Cu species on ZSM-5/SAPO34 catalysts.

  11. Wavelet Analyses and Applications

    ERIC Educational Resources Information Center

    Bordeianu, Cristian C.; Landau, Rubin H.; Paez, Manuel J.

    2009-01-01

    It is shown how a modern extension of Fourier analysis known as wavelet analysis is applied to signals containing multiscale information. First, a continuous wavelet transform is used to analyse the spectrum of a nonstationary signal (one whose form changes in time). The spectral analysis of such a signal gives the strength of the signal in each…

  12. Apollo 14 microbial analyses

    NASA Technical Reports Server (NTRS)

    Taylor, G. R.

    1972-01-01

    Extensive microbiological analyses that were performed on the Apollo 14 prime and backup crewmembers and ancillary personnel are discussed. The crewmembers were subjected to four separate and quite different environments during the 137-day monitoring period. The relation between each of these environments and observed changes in the microflora of each astronaut are presented.

  13. MULTIPLE ABSORPTION-LINE SPECTROSCOPY OF THE INTERGALACTIC MEDIUM. I. MODEL

    SciTech Connect

    Yao Yangsen; Michael Shull, J.; Danforth, Charles W.; Keeney, Brian A.; Stocke, John T.

    2011-04-01

    We present a physically based absorption-line model for the spectroscopic study of the intergalactic medium (IGM). This model adopts results from Cloudy simulations and theoretical calculations by Gnat and Sternberg to examine the resulting observational signatures of the absorbing gas with the following ionization scenarios: collisional ionization equilibrium (CIE), photoionization equilibrium, hybrid (photo- plus collisional ionization), and non-equilibrium cooling. As a demonstration, we apply this model to new observations made with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope of the IGM absorbers at z {approx} 0.1877 along the 1ES 1553+113 sight line. We identify Ly{alpha}, C III, O VI, and N V absorption lines with two distinct velocity components (blue at z{sub b} = 0.18757; red at z{sub r} = 0.18772) separated by {Delta}(cz)/(1 + z) {approx} 38 km s{sup -1}. Joint analyses of these lines indicate that none of the examined ionization scenarios can be applied with confidence to the blue velocity component, although photoionization seems to play a dominant role. For the red component, CIE can be ruled out, but pure photoionization and hybrid scenarios (with T < 1.3 x 10{sup 5} K) are more acceptable. The constrained ranges of hydrogen density and metallicity of the absorbing gas are n{sub H} = (1.9-2.3) x 10{sup -5} cm{sup -3} and Z = (0.43-0.67) Z{sub sun}. These constraints indicate O VI and H I ionization fractions, f{sub OVI} = 0.10-0.15 and f{sub HI} = (3.2-5.1) x 10{sup -5}, with total hydrogen column density N{sub H} = (0.7-1.2) x 10{sup 18} cm{sup -2}. This demonstration shows that the joint analysis of multiple absorption lines can constrain the ionization state of an absorber, and results used to estimate the baryonic matter contained in the absorber.

  14. Tunable diode-laser absorption measurements of methane at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Nagali, V.; Chou, S. I.; Baer, D. S.; Hanson, R. K.; Segall, J.

    1996-07-01

    A diode-laser sensor system based on absorption spectroscopy techniques has been developed to monitor CH4 nonintrusively in high-temperature environments. Fundamental spectroscopic parameters, including the line strengths of the transitions in the R(6) manifold of the 2 nu 3 band near 1.646 mu m, have been determined from high-resolution absorption measurements in a heated static cell. In addition, a corrected expression for the CH 4 partition function has been validated experimentally over the temperature range from 400 to 915 K. Potential applications of the diode-laser sensor system include process control, combustion measurements, and atmospheric monitoring.

  15. Information Omitted From Analyses.

    PubMed

    2015-08-01

    In the Original Article titled “Higher- Order Genetic and Environmental Structure of Prevalent Forms of Child and Adolescent Psychopathology” published in the February 2011 issue of JAMA Psychiatry (then Archives of General Psychiatry) (2011;68[2]:181-189), there were 2 errors. Although the article stated that the dimensions of psychopathology were measured using parent informants for inattention, hyperactivity-impulsivity, and oppositional defiant disorder, and a combination of parent and youth informants for conduct disorder, major depression, generalized anxiety disorder, separation anxiety disorder, social phobia, specific phobia, agoraphobia, and obsessive-compulsive disorder, all dimensional scores used in the reported analyses were actually based on parent reports of symptoms; youth reports were not used. In addition, whereas the article stated that each symptom dimension was residualized on age, sex, age-squared, and age by sex, the dimensions actually were only residualized on age, sex, and age-squared. All analyses were repeated using parent informants for inattention, hyperactivity-impulsivity, and oppositional defiant disorder, and a combination of parent and youth informants for conduct disorder,major depression, generalized anxiety disorder, separation anxiety disorder, social phobia, specific phobia, agoraphobia, and obsessive-compulsive disorder; these dimensional scores were residualized on age, age-squared, sex, sex by age, and sex by age-squared. The results of the new analyses were qualitatively the same as those reported in the article, with no substantial changes in conclusions. The only notable small difference was that major depression and generalized anxiety disorder dimensions had small but significant loadings on the internalizing factor in addition to their substantial loadings on the general factor in the analyses of both genetic and non-shared covariances in the selected models in the new analyses. Corrections were made to the

  16. Optical Spectroscopic Monitoring of Parachute Yarn Aging

    SciTech Connect

    Tallant, D.R.; Garcia, M.J.; Simpson, R.L.; Behr, V.L.; Whinery, L.D.; Peng, L.W.

    1999-04-01

    Optical spectroscopic techniques were evaluated as nondestructive monitors of the aging of parachutes in nuclear weapons. We analyzed thermally aged samples of nylon and Kevlar webbing by photoluminescence spectroscopy and reflection spectroscopy. Infrared analysis was also performed to help understand the degradation mechanisms of the polymer materials in the webbing. The photoluminescence and reflection spectra were analyzed by chemometric data treatment techniques to see if aged-induced changes in the spectra correlated to changes in measured tensile strength. A correlation was found between the shapes of the photoluminescent bands and the measured tensile strengths. Photoluminescent spectra can be used to predict the tensile strengths of nylon and Kevlar webbing with sufficient accuracy to categorize the webbing sample as above rated tensile strength, marginal or below rated tensile strength. The instrumentation required to perform the optical spectroscopic measurement can be made rugged, compact and portable. Thus, optical spectroscopic techniques offer a means for nondestructive field monitoring of parachutes in the enduring stockpile/

  17. Laboratory spectroscopic analyses of electron irradiated alkanes and alkenes in solar system ices

    NASA Astrophysics Data System (ADS)

    Hand, K. P.; Carlson, R. W.

    2012-03-01

    We report results from laboratory experiments of 10 keV electron irradiation of thin ice films of water and short-chain hydrocarbons at ˜10-8 Torr and temperatures ranging from 70-100 K. Hydrocarbon mixtures include water with C3H8, C3H6, C4H10 (butane and isobutane), and C4H8, (1-butene and cis/trans-2-butene). The double bonds of the alkenes in our initial mixtures were rapidly destroyed or converted to single carbon bonds, covalent bonds with hydrogen, bonds with -OH (hydroxyl), bonds with oxygen (C-O), or double bonds with oxygen (carbonyl). Spectra resulting from irradiation of alkane and alkene ices are largely indistinguishable; the initial differences in film composition are destroyed and the resulting mixture includes long-chain, branched aliphatics, aldehydes, ketones, esters, and alcohols. Methane was observed as a product during radiolysis but CO was largely absent. We find that while some of the carbon is oxidized and lost to CO2 formation, some carbon is sequestered into highly refractory, long-chain aliphatic compounds that remain as a thin residue even after the ice film has been raised to standard temperature and pressure. We conclude that the high availability of hydrogen in our experiments leads to the formation of the formyl radical which then serves as the precursor for formaldehyde and polymerization of longer hydrocarbon chains.

  18. Optical spectroscopic and reverse-phase HPLC analyses of Hg(II) binding to phytochelatins.

    PubMed

    Mehra, R K; Miclat, J; Kodati, V R; Abdullah, R; Hunter, T C; Mulchandani, P

    1996-02-15

    Optical spectroscopy and reverse-phase HPLC were used to investigate the binding of Hg(II) to plant metal-binding peptides (phytochelatins) with the structure (gammaGlu-Cys)2Gly, (gammaGlu-Cys)3Gly and (gammaGlu-Cys)4Gly. Glutathione-mediated transfer of Hg(II) into phytochelatins and the transfer of the metal ion from one phytochelatin to another was also studied using reverse-phase HPLC. The saturation of Hg(II)-induced bands in the UV/visible and CD spectra of (gammaGlu-Cys)2Gly suggested the formation of a single Hg(II)-binding species of this peptide with a stoichiometry of one metal ion per peptide molecule. The separation of apo-(gammaGlu-Cys)2Gly from its Hg(II) derivative on a C18 reverse-phase column also indicated the same metal-binding stoichiometry. The UV/visible spectra of both (gammaGlu-Cys)3Gly and (gammaGlu-Cys)4Gly at pH 7.4 showed distinct shoulders in the ligand-to-metal charge-transfer region at 280-290 mm. Two distinct Hg(II)-binding species, occurring at metal-binding stoichiometries of around 1.25 and 2.0 Hg(II) ions per peptide molecule, were observed for (gammaGlu-Cys)3Gly. These species exhibited specific spectral features in the charge-transfer region and were separable by HPLC. Similarly, two main Hg(II)-binding species of (gammaGlu-Cys)4Gly were observed by UV/visible and CD spectroscopy at metal-binding stoichiometries of around 1.25 and 2.5 respectively. Only a single peak of Hg(II)-(gammaGlu-Cys)4Gly complexes was resolved under the conditions used for HPLC. The overall Hg(II)-binding stoichiometries of phytochelatins were similar at pH 2.0 and at pH 7.4, indicating that pH did not influence the final Hg(II)-binding capacity of these peptides. The reverse-phase HPLC assays indicated a rapid transfer of Hg(II) from glutathione to phytochelatins. These assays also demonstrated a facile transfer of the metal ion from shorter- to longer-chain phytochelatins. The strength of Hg(II) binding to glutathione and phytochelatins followed the order: gammaGlu-Cys-Gly<(gammaGlu-Cys)2Gly<(gammaGlu-Cy s)3Gly<(gamma Glu-Cys)4Gly. PMID:8660312

  19. Mushroom (Agaricus bisporus) polyphenoloxidase inhibited by apigenin: Multi-spectroscopic analyses and computational docking simulation.

    PubMed

    Xiong, Zhiqiang; Liu, Wei; Zhou, Lei; Zou, Liqiang; Chen, Jun

    2016-07-15

    It has been revealed that some polyphenols can prevent enzymatic browning caused by polyphenoloxidase (PPO). Apigenin, widely distributed in many fruits and vegetables, is an important bioactive flavonoid compound. In this study, apigenin exhibited a strong inhibitory activity against PPO, and some reagents had synergistic effect with apigenin on inhibiting PPO. Apigenin inhibited PPO activity reversibly in a mixed-type manner. The fact that inactivation rate constant (k) of PPO increased while activation energy (Ea) and thermodynamic parameters (ΔG, ΔH and ΔS) decreased indicated that the thermosensitivity and stability of PPO decreased. The conformational changes of PPO were revealed by fluorescence emission spectra and circular dichroism. Atomic force microscopy observation suggested that the dimension of PPO molecules was larger after interacting with apigenin. Moreover, computational docking simulation indicated that apigenin bound to PPO and inserted into the hydrophobic cavity of PPO to interact with some amino acid residues. PMID:26948635

  20. Spectroscopic analyses on interaction of bovine serum albumin with novel spiro[cyclopropane-pyrrolizin

    NASA Astrophysics Data System (ADS)

    Yu, Xianyong; Liao, Zhixi; Jiang, Bingfei; Hu, Xiaolian; Li, Xiaofang

    2015-02-01

    The interaction between novel spiro[cyclopropane-pyrrolizin] (NSCP) and bovine serum albumin (BSA) was analyzed by fluorescence and ultraviolet-visible (UV-Vis) spectroscopy at 298 K, 304 K and 310 K under simulative physiological conditions. The results showed that NSCP can effectively quench the intrinsic fluorescence of BSA via static quenching. The binding constants, binding sites of NSCP with BSA were calculated. Hydrogen binds and van der Waals force played a major role in stabilizing the complex and the binding reaction were spontaneous. According to the Förster non-radiation energy transfer theory, the average binding distances between NSCP and BSA were obtained. What is more, the synchronous fluorescence spectra indicated that the conformation of BSA has been changed.

  1. Spectroscopic, thermal analyses, structural and antibacterial studies on the interaction of some metals with ofloxacin

    NASA Astrophysics Data System (ADS)

    Zordok, W. A.; El-Shwiniy, W. H.; El-Attar, M. S.; Sadeek, S. A.

    2013-09-01

    Reaction between the fluoroquinolone antibacterial agent ofloxacin and V(IV), Zr(IV) and U(VI) in methanol and acetone was studied. The ability of ofloxacin to form metal complexes is high. The isolated solid complexes were characterized by elemental analysis, magnetic moment, conductance measurements, infrared, electronic, 1H NMR spectra and thermal investigation. In all complexes the ofloxacin ligand is coordinated through the pyridone and carboxylate oxygen forming 1:2 M:HOfl complexes. The calculated bond length and force constant, F(Udbnd O), in the uranyl complex are 1.73 Å and 640.83 N m-1, respectively. The metal-ligand binding of the V(IV) and Zr(IV) complexes was predicted by using the density functional theory (DFT) at the B3LYP-CEP-31G level of theory and total energy, dipole moment estimation of different V(IV) and Zr(IV) ofloxacin structures. All the synthesized complexes exhibited higher biocidal activity against S. aureus K1, Bacillus subtilis K22, Br. otitidis K76, Escherichia coli K32, Pseudomonas aeruginosa SW1 and Klebsiella oxytoca K42. compared to parent compounds and standard drugs.

  2. Compositional, spectroscopic and rheological analyses of mucilage isolated from taro (Colocasia esculenta L. Schott) corms.

    PubMed

    Njintang, Nicolas Yanou; Boudjeko, Thaddee; Tatsadjieu, Leopold Ngoune; Nguema-Ona, Eric; Scher, Joel; Mbofung, Carl M F

    2014-05-01

    Tropical roots and tubers generally contain mucilage. These mucilages exhibit unique rheological properties with considerable potential as a food thickener and stabilizer. A one-step extraction procedure was used to isolate starch free mucilage and associated proteins from a number of taro (Colocasia esculenta) varieties. The monosaccharide and amino acid composition, the structural and flow properties were investigated. The results showed that yield of mucilage fraction varied from 30 to 190 g.kg(-1). A negative correlation (r = -0.87; p < 0.05) was observed between the crude protein level and the yield. The monosaccharide profiles revealed that galactose, mannose and arabinose were the main monosaccharides in the hydrolysate of the mucilage. From the 17 amino acids analyzed, aspartic acid/asparagine (14.4-17.2%) and glutamic acid/glutamine (10.3-13.6%) were prominent in the mucilage as well as the flour. No significant differences were observed in the FT-IR spectra and in the viscosity behavior of the mucilage dispersions. The greatest difference in the mucilage is based on its monosaccharide profile while the protein composition, which reflects that of the flour, is relatively stable. PMID:24803696

  3. IR and UV spectroscopic studies at low temperature: C2N2

    NASA Astrophysics Data System (ADS)

    Benilan, Y.; Arzoumanian, E.; Es-Sebbar, Et.; Ferradaz, T.; Fray, N.; Jolly, A.; Gazeau, M.-C.; Schwell, M.

    2008-09-01

    Titan's atmosphere is mainly made of nitrogen and methane and is furthermore very rich in organic molecules. Hydrocarbons are formed by the photodissociation of CH4 and nitriles are created by dissociation of N2 followed by reactions with hydrocarbons. In order to understand the physicochemical mechanisms responsible for the evolution of Titan's atmosphere, photochemical models are built. The latter needs constraints for the determination of vertical profiles of organic compounds, from the higher thermosphere down to the lower stratosphere. They also need wavelength dependant photodissociation rates as input parameters. Vertical profiles can be retrieved from Cassini observations along the entire atmosphere, in particular by limb sounding using Cassini's UVIS and CIRS spectrometers. However, in order to interpret data obtained by these instruments, precise spectroscopic parameters and their dependence on temperature are needed. We will review the current knowledge in this field of planetary spectroscopy and point out the lack of spectroscopic parameters of already detected species. These parameters are especially needed for radiative transfer calculations at low temperatures. We will focus our talk on the Cyanogen molecule (C2N2) which has been observed in Titan's atmosphere in the FIR domain, around 230 cm-1. We will present the latest spectroscopic studies we have performed on this molecule which cover the entire spectrum from the mid- infrared to the vacuum ultraviolet spectral region. Integrated band intensities have been determined for all bands in the infrared. In the ultraviolet domain, we have determined absolute cross sections from 350 down to 80 nm covering six orders of magnitude for the absorption coefficient. We will also show how temperature can influence VUV absorption coefficients. The corresponding implications of temperature dependant absorption data on the interpretation of UVIS observations will be discussed.

  4. Intestinal folate absorption

    PubMed Central

    Strum, Williamson; Nixon, Peter F.; Bertino, Joseph B.; Binder, Henry J.

    1971-01-01

    Intestinal absorption of the monoglutamate form of the principal dietary and circulating folate compound, 5-methyltetrahydrofolic acid (5-MTHF), was studied in the rat utilizing a synthetic highly purified radiolabeled diastereoisomer. Chromatography confirmed that the compound was not altered after transfer from the mucosa to the serosa. Accumulation against a concentration gradient was not observed in duodenal, jejunal, or ileal segments at 5-MTHF concentration from 0.5 to 500 nmoles/liter. Unidirectional transmural flux determination also did not indicate a significant net flux. Mucosal to serosal transfer of 5-MTHF was similar in all segments of the intestine and increased in a linear fashion with increased initial mucosal concentrations. Further, no alteration in 5-MTHF transfer was found when studied in the presence of metabolic inhibitors or folate compounds. These results indicate that 5-MTHF is not absorbed by the rat small intestine by a carrier-mediated system and suggest that 5-MTHF transfer most likely represents diffusion. Images PMID:5564397

  5. Analytical Raman spectroscopic discrimination between yellow pigments of the Renaissance

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G. M.

    2011-10-01

    The Renaissance represented a major advance in painting techniques, subject matter, artistic style and the use of pigments and pigment mixtures. However, most pigments in general use were still mineral-based as most organic dyes were believed to be fugitive; the historical study of artists' palettes and recipes has assumed importance for the attribution of art works to the Renaissance period. Although the application of diagnostic elemental and molecular spectroscopic techniques play vital and complementary roles in the analysis of art works, elemental techniques alone cannot definitively provide the data needed for pigment identification. The advantages and limitations of Raman spectroscopy for the definitive diagnostic characterisation of yellow pigments that were in use during the Renaissance is demonstrated here in consideration of heavy metal oxides and sulphides; these data will be compared with those obtained from analyses of synthetic yellow pigments that were available during the eighteenth and nineteenth Centuries which could have been used in unrecorded restorations of Renaissance paintings.

  6. Spectroscopic study of carbonaceous dust particles grown in benzene plasma

    SciTech Connect

    Lee, Szetsen; Chen, H.-F.; Chin, C.-J.

    2007-06-01

    Carbonaceous dust particles have been synthesized from benzene using an rf glow discharge. Scanning electron microscope inspection revealed that the plasma-synthesized dust particles can be classified into two types. Shell-structured dust particles showed a wide size distribution from 3 to40 {mu}m. The other type, with different degrees of aggregation, appeared to be dense and spherical with a very distinctive yellow color and size distribution from 100 nm to 2 {mu}m. Analyses using micro-Raman and Fourier transform infrared microscopy indicated that the main components of the dust particles are polyphenyls and hydrogenated amorphous carbon (HAC). The luminescence background in Raman spectra and the infrared C-H stretching vibrational features observed around 3.4 {mu}m for the dust particles are attributed to HAC. The formation mechanisms and spectroscopic characterization of carbonaceous dust particles are discussed.

  7. Raman spectroscopic study of "The Malatesta": a Renaissance painting?

    PubMed

    Edwards, Howell G M; Vandenabeele, Peter; Benoy, Timothy J

    2015-02-25

    Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research. PMID:25194320

  8. Spectroscopic Analysis of Impurity Precipitates in CdS Films

    SciTech Connect

    Webb, J. D.; Keane, J.; Ribelin, R.; Gedvilas, L.; Swartzlander, A.; Ramanathan, K.; Albin, D. S.; Noufi, R.

    1999-10-31

    Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Devices incorporating chemical-bath-deposited (CBD) CdS are comparable in quality to devices incorporating purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this paper, we summarize and review the results of Fourier transform infrared (FTIR), Auger, electron microprobe, and X-ray photoelectron spectroscopic (XPS) analyses of the impurities in CBD CdS films. We show that these impurities differ as a function of substrate type and film deposition conditions. We also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

  9. Spectroscopic and quantum chemical studies on 4-acryloyl morpholine

    NASA Astrophysics Data System (ADS)

    Arjunan, V.; Rani, T.; Santhanalakshmi, K.; Mohan, S.

    2011-09-01

    Fourier transform infrared (FTIR) and FT-Raman spectra have been recorded and an extensive spectroscopic investigations have been carried out on 4-acryloyl morpholine (4AM). Theoretical quantum chemical studies have also been performed. From the ab initio and DFT analysis using HF, B3LYP and B3PW91 methods with 6-31G(d,p) and 6-311G++(d,p) basis sets the energies, structural, thermodynamical and vibrational characteristics of the compound were determined. The energy difference between the chair equatorial and chair axial conformers of 4AM have been calculated by density functional theory (DFT) method. The optimized geometrical parameters, theoretical wavenumbers and thermodynamic properties of the molecule are compared with the experimental values. The effect of acryloyl group on the characteristic frequencies of the morpholine ring has been analysed. The mixing of the fundamental modes with the help of potential energy distribution (PED) through normal co-ordinate analysis has been discussed.

  10. Experimental and theoretical investigations on spectroscopic properties of the imidazole-fused phenanthroline and its derivatives.

    PubMed

    Zhong, Rongfeng; Xu, Shengxian; Wang, Jinglan; Zhao, Feng; Xia, Hongying; Wang, Yibo

    2016-05-15

    Two phenanthroline derivatives, 1H-imidazo[4,5-f][1,10]phenanthroline (imPhen) and 2-(9H-fluoren-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (Flu-imPhen), have been synthesized and characterized and the corresponding absorption and emission spectroscopic properties have been studied in CH2Cl2 solution. The imPhen exhibits the main two absorption bands at 282 nm and 229 nm and these bands are assigned as the typical π→π*(Phen) state. In addition, the weak absorption bands at 313 nm associated with a shoulder near 302 nm were assigned to the π→π*(Phen) state with partial charge transfer (CT) character. A similar absorption spectra are observed in the case of the Flu-imPhen in the region of 200-300 nm, while the region of 300-400 nm of the spectra are dominated by the characteristic π→π* transition of the fluorene moiety. imPhen shows the typical ligand-centered (1)π→π* emission, while Flu-imPhen emits from the mixed (1)π→π*/CT states. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) were employed to rationalize the photophysical properties of these ligands studied. The theoretical data confirm the assignment of the experimental absorption spectra and the nature of the emitting states. PMID:26943490

  11. Experimental and theoretical investigations on spectroscopic properties of the imidazole-fused phenanthroline and its derivatives

    NASA Astrophysics Data System (ADS)

    Zhong, Rongfeng; Xu, Shengxian; Wang, Jinglan; Zhao, Feng; Xia, Hongying; Wang, Yibo

    2016-05-01

    Two phenanthroline derivatives, 1H-imidazo[4,5-f][1,10]phenanthroline (imPhen) and 2-(9H-fluoren-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (Flu-imPhen), have been synthesized and characterized and the corresponding absorption and emission spectroscopic properties have been studied in CH2Cl2 solution. The imPhen exhibits the main two absorption bands at 282 nm and 229 nm and these bands are assigned as the typical π → π*(Phen) state. In addition, the weak absorption bands at 313 nm associated with a shoulder near 302 nm were assigned to the π → π*(Phen) state with partial charge transfer (CT) character. A similar absorption spectra are observed in the case of the Flu-imPhen in the region of 200-300 nm, while the region of 300-400 nm of the spectra are dominated by the characteristic π → π* transition of the fluorene moiety. imPhen shows the typical ligand-centered 1π → π* emission, while Flu-imPhen emits from the mixed 1π → π*/CT states. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) were employed to rationalize the photophysical properties of these ligands studied. The theoretical data confirm the assignment of the experimental absorption spectra and the nature of the emitting states.

  12. Solar Absorption in Cloudy Atmospheres

    NASA Technical Reports Server (NTRS)

    Harshvardhan; Ridgway, William; Ramaswamy, V.; Freidenreich, S. M.; Batey, Michael

    1996-01-01

    The theoretical computations used to compute spectral absorption of solar radiation are discussed. Radiative properties relevant to the cloud absorption problem are presented and placed in the context of radiative forcing. Implications for future measuring programs and the effect of horizontal inhomogeneities are discussed.

  13. Atlas of Infrared Absorption Lines

    NASA Technical Reports Server (NTRS)

    Park, J. H.

    1977-01-01

    This atlas of infrared absorption line contains absorption line parameters (line strength vs. wavenumber) from 500 to 7000 cm(exp-1) for 15 gases: H2O, CO2, O3, N2O, CO, CH4, O2, SO2, NO, NO2, NH3, HCl, HF, HNO3 and CH3Cl.

  14. Hot tube atomic absorption spectrochemistry.

    PubMed

    Woodriff, R; Stone, R W

    1968-07-01

    A small, commercially available atomic absorption instrument is used with a heated graphite tube for the atomic absorption analysis of liquid and solid silver samples. Operating conditions of the furnace are described and a sensitivity of about 5 ng of silver is reported. PMID:20068797

  15. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  16. Atmospheric absorption of sound - Update

    NASA Technical Reports Server (NTRS)

    Bass, H. E.; Sutherland, L. C.; Zuckerwar, A. J.

    1990-01-01

    Best current expressions for the vibrational relaxation times of oxygen and nitrogen in the atmosphere are used to compute total absorption. The resulting graphs of total absorption as a function of frequency for different humidities should be used in lieu of the graph published earlier by Evans et al (1972).

  17. Atomic Absorption Spectroscopy. The Present and the Future.

    ERIC Educational Resources Information Center

    Slavin, Walter

    1982-01-01

    The status of current techniques and methods of atomic absorption (AA) spectroscopy (flame, hybrid, and furnace AA) is discussed, including limitations. Technological opportunities and how they may be used in AA are also discussed, focusing on automation, microprocessors, continuum AA, hybrid analyses, and others. (Author/JN)

  18. Fine-structure Constancy Measurements in QSO Absorption Lines

    NASA Astrophysics Data System (ADS)

    Whitmore, Jonathan B.

    2013-01-01

    The ESO Large Programme 185.A-0745 has awarded 10 nights on the VLT-UVES spectrograph for the study of the possible variation in the fine structure constant. We will present the fine-structure measurements from two lines of sight and several absorption systems. We will also present updated systematic error analyses.

  19. Fluorescence Spectroscopic Properties of Normal and Abnormal Biomedical Materials

    NASA Astrophysics Data System (ADS)

    Pradhan, Asima

    Steady state and time-resolved optical spectroscopy and native fluorescence is used to study the physical and optical properties occurring in diseased and non-diseased biological human tissue, in particular, cancer of the human breast, artery and the dynamics of a photosensitizer useful in photodynamic therapy. The main focus of the research is on the optical properties of cancer and atherosclerotic tissues as compared to their normal counterparts using the different luminescence based spectroscopic techniques such as steady state fluorescence, time-resolved fluorescence, excitation spectroscopy and phosphorescence. The excitation and steady-state spectroscopic fluorescence using visible excitation wavelength displays a difference between normal and malignant tissues. This difference is attributed to absorption of the emission by hemoglobin in normal tissues. This method using 488nm fails to distinguish neoplastic tissue such as benign tissues and tumors from malignant tumors. The time-resolved fluorescence at visible, near -uv and uv excitation wavelengths display non-exponential profiles which are significantly different for malignant tumors as compared to non-malignant tissues only with uv excitation. The differences observed with visible and near-uv excitation wavelengths are not as significant. The non-exponential profiles are interpreted as due to a combination of fluorophores along with the action of non-radiative processes. Low temperature luminescence studies confirm the occurrence of non-radiative decay processes while temporal studies of various relevant biomolecules indicate the probable fluorophores responsible for the observed signal in tissues. Phosphorescence from human tissues have been observed for the first time and lifetimes of a few hundred nanoseconds are measured for malignant and benign tissues. Time-resolved fluorescence studies of normal artery and atherosclerotic plaque have shown that a combination of two excitation wavelengths can

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  1. Hemodynamic analysis of patients in intensive care unit based on diffuse optical spectroscopic imaging system

    NASA Astrophysics Data System (ADS)

    Hsieh, Yao-Sheng; Wang, Chun-Yang; Ling, Yo-Wei; Chuang, Ming-Lung; Chuang, Ching-Cheng; Tsai, Jui-che; Lu, Chih-Wei; Sun, Chia-Wei

    2010-02-01

    Diffuse optical spectroscopic imaging (DOSI) is a technique to assess the spatial variation in absorption and scattering properties of the biological tissues and provides the monitoring of changes in concentrations of oxy-hemoglobin and deoxy-hemoglobin. In our preliminary study, the temporal tracings of hemodynamic oxygenation are measured with DOSI and venous occlusion test (VOT) from normal subjects, patients with heart failure and patients with sepsis in intensive care unit (ICU). In experiments, the obvious differences of hemodynamic signals can be observed among the three groups. The physiological relevance of VOT hemodynamics with respect to diseases is also discussed in this paper.

  2. FESTR: Finite-Element Spectral Transfer of Radiation spectroscopic modeling and analysis code

    DOE PAGESBeta

    Hakel, Peter

    2016-06-16

    Here we report on the development of a new spectral postprocessor of hydrodynamic simulations of hot, dense plasmas. Based on given time histories of one-, two-, and three-dimensional spatial distributions of materials, and their local temperature and density conditions, spectroscopically-resolved signals are computed. The effects of radiation emission and absorption by the plasma on the emergent spectra are simultaneously taken into account. This program can also be used independently of hydrodynamic calculations to analyze available experimental data with the goal of inferring plasma conditions.

  3. High temperature and high pressure gas cell for quantitative spectroscopic measurements

    NASA Astrophysics Data System (ADS)

    Christiansen, Caspar; Stolberg-Rohr, Thomine; Fateev, Alexander; Clausen, Sønnik

    2016-01-01

    A high temperature and high pressure gas cell (HTPGC) has been manufactured for quantitative spectroscopic measurements in the pressure range 1-200 bar and temperature range 300-1300 K. In the present work the cell was employed at up to 100 bar and 1000 K, and measured absorption coefficients of a CO2-N2 mixture at 100 bar and 1000 K are revealed for the first time, exceeding the high temperature and pressure combinations previously reported. This paper discusses the design considerations involved in the construction of the cell and presents validation measurements compared against simulated spectra, as well as published experimental data.

  4. Spatial pattern separation of chemicals and frequency-independent components by terahertz spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Watanabe, Yuuki; Kawase, Kodo; Ikari, Tomofumi; Ito, Hiromasa; Ishikawa, Youichi; Minamide, Hiroaki

    2003-10-01

    We separated the component spatial patterns of frequency-dependent absorption in chemicals and frequency-independent components such as plastic, paper, and measurement noise in terahertz (THz) spectroscopic images, using known spectral curves. Our measurement system, which uses a widely tunable coherent THz-wave parametric oscillator source, can image at a specific frequency in the range 1-2 THz. The component patterns of chemicals can easily be extracted by use of the frequency-independent components. This method could be successfully used for nondestructive inspection for the detection of illegal drugs and devices of bioterrorism concealed, e.g., inside mail and packages.

  5. Spectroscopic, luminescent and laser properties of nanostructured CaF2:Tm materials

    NASA Astrophysics Data System (ADS)

    Lyapin, A. A.; Fedorov, P. P.; Garibin, E. A.; Malov, A. V.; Osiko, V. V.; Ryabochkina, P. A.; Ushakov, S. N.

    2013-08-01

    The laser quality transparent СаF2:Tm fluoride ceramics has been prepared by hot forming. Comparative study of absorption and emission spectra of СаF2:Tm (4 mol.% TmF3) ceramic and single crystal samples demonstrated that these materials possess almost identical spectroscopic properties. Laser oscillations of СаF2:Tm ceramics were obtained at 1898 nm under diode pumping, with the slope efficiency of 5.5%. Also, the continuous-wave (CW) laser have been obtained for СаF2:Tm single crystal at 1890 nm pumped by a diode laser was demonstrated.

  6. Optical properties of monolayer transition metal dichalcogenides probed by spectroscopic ellipsometry

    SciTech Connect

    Liu, Hsiang-Lin Shen, Chih-Chiang; Su, Sheng-Han; Hsu, Chang-Lung; Li, Ming-Yang; Li, Lain-Jong

    2014-11-17

    Spectroscopic ellipsometry was used to characterize the complex refractive index of chemical-vapor-deposited monolayer transition metal dichalcogenides (TMDs). The extraordinary large value of the refractive index in the visible frequency range is obtained. The absorption response shows a strong correlation between the magnitude of the exciton binding energy and band gap energy. Together with the observed giant spin-orbit splitting, these findings advance the fundamental understanding of their novel electronic structures and the development of monolayer TMDs-based optoelectronic and spintronic devices.

  7. Spectroscopic methods for the determination of surface-active substances in water (a review)

    SciTech Connect

    Subbotina, E.I.; Dedkov, Yu.M.

    1987-12-01

    Synthetic surfactants, for their ability to mingle with and transform chemicals more toxic in nature such as petroleum products, oils, pesticides, and chlorinated hydrocarbons into substances that easily permeate and move through the hydrosphere into water reservoirs and other exposure pathways, pose a grave danger to water quality control. This paper reviews predominantly the spectrophotometric procedures available for monitoring these surfactants but also discusses fluorimetric, infrared spectroscopic, and atomic absorption procedures, and compares a wide range of solvents and reagents for the extraction and preparatory activation of the surfactants.

  8. Optical absorption of silicon nanowires

    SciTech Connect

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stievenard, D.; Leveque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2012-08-01

    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  9. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  10. Anion pairs in room temperature ionic liquids predicted by molecular dynamics simulation, verified by spectroscopic characterization

    SciTech Connect

    Schwenzer, Birgit; Kerisit, Sebastien N.; Vijayakumar, M.

    2014-01-01

    Molecular-level spectroscopic analyses of an aprotic and a protic room-temperature ionic liquid, BMIM OTf and BMIM HSO4, respectively, have been carried out with the aim of verifying molecular dynamics simulations that predict anion pair formation in these fluid structures. Fourier-transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy of various nuclei support the theoretically-determined average molecular arrangements.

  11. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  12. Localized and Spectroscopic Orbitals: Squirrel Ears on Water.

    ERIC Educational Resources Information Center

    Martin, R. Bruce

    1988-01-01

    Reexamines the electronic structure of water considering divergent views. Discusses several aspects of molecular orbital theory using spectroscopic molecular orbitals and localized molecular orbitals. Gives examples for determining lowest energy spectroscopic orbitals. (ML)

  13. Characterization of selenium in UO2 spent nuclear fuel by micro X-ray absorption spectroscopy and its thermodynamic stability.

    PubMed

    Curti, E; Puranen, A; Grolimund, D; Jädernas, D; Sheptyakov, D; Mesbah, A

    2015-10-01

    Direct disposal of spent nuclear fuel (SNF) in deep geological formations is the preferred option for the final storage of nuclear waste in many countries. In order to assess to which extent radionuclides could be released to the environment, it is of great importance to understand how they are chemically bound in the waste matrix. This is particularly important for long-lived radionuclides such as (79)Se, (129)I, (14)C or (36)Cl, which form poorly sorbing anionic species in water and therefore migrate without significant retardation through argillaceous repository materials and host rocks. We present here X-ray absorption spectroscopic data providing evidence that in the investigated SNF samples selenium is directly bound to U atoms as Se(-II) (selenide) ion, probably replacing oxygen in the cubic UO2 lattice. This result is corroborated by a simple thermodynamic analysis, showing that selenide is the stable form of Se under reactor operation conditions. Because selenide is almost insoluble in water, our data indirectly explain the unexpectedly low release of Se in short-term aqueous leaching experiments, compared to iodine or cesium. These results have a direct impact on safety analyses for potential nuclear waste repository sites, as they justify assuming a small fractional release of selenium in performance assessment calculations. PMID:26365814

  14. Asiago spectroscopic classification of AT 2016cvm

    NASA Astrophysics Data System (ADS)

    Tomasella, L.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Ochner, P.; Tartaglia, L.; Terreran, G.; Turatto, M.

    2016-06-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of AT 2016cvm (also known as PTSS-16hxs), discovered 20160613.771 by the PMO-Tsinghua Supernova Survey (PTSS) The observation was performed with the Asiago 1.82 m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.4 nm).

  15. Asiago spectroscopic classification of four SNe

    NASA Astrophysics Data System (ADS)

    Pastorello, A.; Tartaglia, L.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Ochner, P.; Terreran, G.; Tomasella, L.; Turatto, M.

    2015-12-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classifications of PS15cym in GALEXASC J011024.12+232124.1, CSS151130:014258+273410 in an anonymous galaxy, PSN J05225991-0008174 in UGC 3301 and ASASSN-15tj in SDSS J075527.63+520911.1 (ATel #8358).

  16. Spectroscopic Classification of Three PSST Transients

    NASA Astrophysics Data System (ADS)

    Blanchard, P.; Nicholl, M.; Berger, E.; Fong, W.; Chornock, R.

    2016-04-01

    We obtained spectroscopic observations on 2016 April 6 UT (range 3000-10600 Angstroms) of three transients reported by the Pan-STARRS Survey for Transients (PSST; Huber et al., ATel #7153; http://star.pst.qub.ac.uk/ps1threepi/) using IMACS mounted on the 6.5m Magellan/Baade Telescope.

  17. Asiago spectroscopic classification of ASASSN-15db

    NASA Astrophysics Data System (ADS)

    Ochner, P.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Tartaglia, L.; Terreran, G.; Tomasella, L.; Turatto, M.

    2015-02-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic observation of ASASSN-15db in NGC 5996. The observation was performed with the Asiago 1.82m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.4 nm), equipped with the CCD Andor IKON L936.

  18. Asiago spectroscopic classification of three SNe

    NASA Astrophysics Data System (ADS)

    Elias-Rosa, N.; Cappellaro, E.; Benetti, S.; Milan, M.; Miluzio, M.; Ochner, P.; Pastorello, A.; Tartaglia, L.; Terreran, G.; Tomasella, L.; Turatto, M.; Morales-Garoffolo, A.; Huang, F.

    2014-10-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of two SNe. The observations were performed with the Asiago 1.82 m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.2 nm).

  19. Spectroscopic mode identification in gamma Doradus stars

    NASA Astrophysics Data System (ADS)

    Rylvia Pollard, Karen

    2015-08-01

    The MUSICIAN programme at the University of Canterbury has been successfully identifying frequencies and pulsation modes in many gamma Doradus stars using hundreds of precise, high resolution spectroscopic observations. This paper describes some of these frequency and mode identifications and the emerging patterns of the programme.

  20. Laser Spectroscopic Measurement Of Temperature And Density

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert L.; Laufer, Gabriel

    1991-01-01

    Report discusses research on use of laser-induced fluorescence in oxygen and Raman scattering in air for simultaneous measurement of temperature and density of air. Major application of laser spectroscopic techniques, measurement of fluctuations of temperature and density in hypersonic flows in wind tunnels.

  1. Spectroscopic study in Z-pinch discharge

    SciTech Connect

    Garamoon, A.A.; Saudy, A.H.; Shark, W.

    1995-12-31

    The temporal variation of the emitted line intensity has been investigated, and thus an important information about the dynamic ionization stages in the Z-pinch discharge has been studied. Also the electron temperature Te, has been deduced by using a spectroscopic technique.

  2. FIRE NIR spectroscopic classifications of optical transients

    NASA Astrophysics Data System (ADS)

    Morrell, N.; Marion, G. H.; Kirshner, R. P.; Hsiao, E. Y.; Stritzinger, M.

    2014-09-01

    We report spectroscopic classifications of 5 supernovae based on near-infrared (NIR) spectroscopy (range 800-2400 nm) obtained on Sept. 3 UT with the FoldedPort Infrared Echellette (FIRE) spectrograph attached to the 6.5-m Magellan Baade Telescope.

  3. FIRE NIR spectroscopic classifications of optical transients

    NASA Astrophysics Data System (ADS)

    Hsiao, E. Y.; Marion, G. H.; Morrell, N.; Phillips, M. M.; Contreras, C.; Gall, C.; Stritzinger, M. D.; Wyrzykowski, L.; Kozlowski, S.; Udalski, A.; Kirshner, R. P.

    2013-12-01

    We report two spectroscopic classifications using near-infrared spectra (range 800-2400 nm) obtained with the FoldedPort Infrared Echellette (FIRE) spectrograph on the 6.5-m Magellan Baade Telescope. All redshifts are from the presumed hosts and approximately match the supernova redshifts.

  4. Asiago spectroscopic classification of ASASSN-16bn

    NASA Astrophysics Data System (ADS)

    Pastorello, A.; Benetti, S.; Tomasella, L.; Cappellaro, E.; Elias-Rosa, N.; Ochner, P.; Tartaglia, L.; Terreran, G.; Turatto, M.

    2016-02-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of ASASSN-16bn (also known as SN 2016adn), discovered by the All Sky Automated Survey for SuperNOvae (ASAS-SN) in 2MASX J03103162+0416184.

  5. Asiago spectroscopic classification of PS15cyk

    NASA Astrophysics Data System (ADS)

    Tartaglia, L.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Ochner, P.; Terreran, G.; Tomasella, L.; Turatto, M.

    2015-12-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of PS15cyk in UGC 12687. The target is supplied by the Pan-STARRS Survey for Transients (see Huber et al., ATel #7153).

  6. Spectroscopic characterization of the Karin family

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Fulchignoni, M.; Birlan, M.; Dotto, E.; Rossi, A.; Fornasier, S.; Marzari, F.; Nesvorny, D.

    2005-08-01

    The Karin asteroidal family was firstly identified by Nesvorny et al. (2002, Nature 417) who numerically integrated the orbits of 39 known members. More recently Nesvorny and Bottke (2004) analyzed a wider sample of objects and, taking into account also the Yarkovsky effect, identified the common origin of 90 family members at 5.75±0.05 Myr in the past. This is an exceptionally young age for an asteroid family. In fact, other known families are thought to be much older, 100 Myr to Gyrs old. We carried out visible and near-infrared spectroscopy of several members of the Karin family. We observed 5 member of the Karin family on November 2003 using the IRTF telescope. These data confirm that 832 Karin is an S-type asteroid (as indicated by Binzel, private communication), characterized by strong absorption features of olivine and pyroxene at about 1 and 2 μ m. Visible spectra for 20 objects were later obtained in December, 2004 with EMMI/NTT (ESO, La Silla) and with MOS/CFHT (Mauna Kea, Hawaii). Fifteen of these objects (832 Karin among them), have S-type spectra with the maximum of each spectra located at a very similar wavelength. This result sustain the hypothesis of a common origin. Five other spectra obtained seem rather primitive (B,C types). We analysed the spectra of the Karin cluster in the context of the Koronis family. This analysis reveals that the spectra are less red than those of the Koronis members. Moreover, we can interpret them as less mature surfaces. Finally, we made an interpretation of the surface composition of 832 Karin, using the Shkuratov scattering model.

  7. Spectral analyses of solar-like stars

    NASA Astrophysics Data System (ADS)

    Doyle, Amanda P.

    2015-03-01

    Accurate stellar parameters are important not just to understand the stars themselves, but also for understanding the planets that orbit them. Despite the availability of high quality spectra, there are still many uncertainties in stellar spectroscopy. In this thesis, the finer details of spectroscopic analyses are discussed and critically evaluated, with a focus on improving the stellar parameters. Using high resolution, high signal-to-noise HARPS spectra, accurate parameters were determined for 22 WASP stars. It is shown that there is a limit to the accuracy of stellar parameters that can be achieved, despite using high S/N spectra. It is also found that the selection of spectral lines used and the accuracy of atomic data is crucial, and different line lists can result in different values of parameters. Different spectral analysis methods often give vastly different results even for the same spectrum of the same star. Here it is shown that many of these discrepancies can be explained by the choice of lines used and by the various assumptions made. This will enable a more reliable homogeneous study of solar-like stars in the future. The Rossiter-McLaughlin effect observed for transiting exoplanets often requires prior knowledge of the projected rotational velocity (vsini). This is usually provided via spectroscopy, however this method has uncertainties as spectral lines are also broadened by photospheric velocity fields known as "macroturbulence". Using rotational splitting frequencies for 28 Kepler stars that were provided via asteroseismology, accurate vsini values have been determined. By inferring the macroturbulence for 28 Kepler stars, it was possible to obtain a new calibration between macroturbulence, effective temperature and surface gravity. Therefore macroturbulence, and thus vsini, can now be determined with confidence for stars that do not have asteroseismic data available. New spectroscopic vsini values were then determined for the WASP planet host

  8. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  9. SO_2 Absorption Cross Sections and N_2 VUV Oscillator Strengths for Planetary Atmosphere Studies

    NASA Astrophysics Data System (ADS)

    Smith, Peter L.; Stark, G.; Rufus, J.; Pickering, J. C.; Cox, G.; Huber, K. P.

    1998-09-01

    The determination of the chemical composition of the atmosphere of Io from Hubble Space Telescope observations in the 190-220 nm wavelength region requires knowledge of the photoabsorption cross sections of SO_2 at temperatures ranging from about 110 K to 300 K. We are engaged in a laboratory program to measure SO_2 absorption cross sections with very high resolving power (lambda /delta lambda =~ 450,000) and at a range of temperatures appropriate to the Io atmosphere. Previous photoabsorption measurements, with lambda /delta lambda =~ 100,000, have been unable to resolve the very congested SO_2 spectrum, and, thus, to elucidate the temperature dependence of the cross sections. Our measurements are being performed at Imperial College, London, using an ultraviolet Fourier transform spectrometer. We will present our recently completed room temperature measurements of SO_2 cross sections in the 190-220 nm region and plans for extending these to ~ 195 K. Analyses of Voyager VUV occultation measurements of the N_2-rich atmospheres of Titan and Triton have been hampered by the lack of fundamental spectroscopic data for N_2, in particular, by the lack of reliable f-values and line widths for electronic bands of N_2 in the 80-100 nm wavelength region. We are continuing our program of measurements of band oscillator strengths for the many (approximately 100) N_2 bands between 80 and 100 nm. We report new f-values, derived from data obtained at the Photon Factory (Tsukuba, Japan) synchrotron radiation facility with lambda /delta lambda =~ 130,000, of 37 bands in the 80-86 nm region and 21 bands in the 90-95 nm region. We have also begun the compilation of a searchable archive of N_2 data on the World Wide Web; see http://cfa-www.harvard. edu/amp/data/n2/n2home.html. The archive, covering the spectroscopy of N_2 between 80 and 100 nm, will include published and unpublished (14) N_2, (14) N(15) N, and (15) N_2 line lists and spectroscopic identifications, excited state energy

  10. Visible-NIR Spectroscopic Evidence for the Composition of Low-Albedo Altered Soils on Mars

    NASA Astrophysics Data System (ADS)

    Murchie, S.; Merenyi, E.; Singer, R.; Kirkland, L.

    1996-03-01

    Spectroscopic studies of altered Martian soils at visible and at NIR wavelengths have generally supported the canonical model of the surface layer as consisting mostly of 2 components, bright red hematite-containing dust and dark gray pyroxene-containing sand. However several of the studies have also provided tantalizing evidence for distinct 1 micrometer Fe absorptions in discrete areas, particularly dark red soils which are hypothesized to consist of duricrust. These distinct absorptions have been proposed to originate from one or more non-hematitic ferric phases. We have tested this hypothesis by merging high spatial resolution visible- and NIR-wavelength data to synthesize composite 0.44-3.14 1lm spectra for regions of western Arabia and Margaritifer Terra. The extended wavelength coverage allows more complete assessment of ferric, ferrous, and H2O absorptions in both wavelength ranges. The composite data show that, compared to nearby bright red soil in Arabia, dark red soil in Oxia has a lower albedo, a more negative continuum slope, and a stronger 3 micrometer H2O absorption . However Fe absorptions are closely similar in position and depth. These results suggest that at least some dark red soils may differ from "normal" dust and mafic sand more in texture than in Fe mineralogy, although there appears to be enrichment in a water-containing phase and/or a dark, spectrally neutral phase. In contrast, there is clear evidence for enrichment of a low-albedo ferric mineral in dark gray soils composing Sinus Meridiani. These have visible- and NIR-wavelength absorptions consistent with crystalline hematite with relatively little pyroxene, plus a very weak 3 micrometer H2O absorption. These properties suggest a Ethology richer in crystalline hematite and less hydrated than both dust and mafic-rich sand.

  11. LDEF Satellite Radiation Analyses

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1996-01-01

    Model calculations and analyses have been carried out to compare with several sets of data (dose, induced radioactivity in various experiment samples and spacecraft components, fission foil measurements, and LET spectra) from passive radiation dosimetry on the Long Duration Exposure Facility (LDEF) satellite, which was recovered after almost six years in space. The calculations and data comparisons are used to estimate the accuracy of current models and methods for predicting the ionizing radiation environment in low earth orbit. The emphasis is on checking the accuracy of trapped proton flux and anisotropy models.

  12. Progress in spectroscopic ellipsometry: Applications from vacuum ultraviolet to infrared

    NASA Astrophysics Data System (ADS)

    Hilfiker, James N.; Bungay, Corey L.; Synowicki, Ron A.; Tiwald, Thomas E.; Herzinger, Craig M.; Johs, Blaine; Pribil, Greg K.; Woollam, John A.

    2003-07-01

    Spectroscopic ellipsometry (SE) is a noncontact and nondestructive optical technique for thin film characterization. In the past 10 yr, it has migrated from the research laboratory into the semiconductor, data storage, display, communication, and optical coating industries. The wide acceptance of SE is a result of its flexibility to measure most material types: dielectrics, semiconductors, metals, superconductors, polymers, biological coatings, and even multilayers of these materials. Measurement of anisotropic materials has also made huge strides in recent years. Traditional SE measurements cover the ultraviolet, visible, and near infrared wavelengths. This spectral range is now acquired within seconds with high accuracy due to innovative optical configurations and charge coupled device detection. In addition, commercial SE has expanded into both the vacuum ultraviolet (VUV) and midinfrared (IR). This wide spectral coverage was achieved by utilizing new optical elements and detection systems, along with UV or Fourier transform IR light sources. Modern instrumentation is now available with unprecedented flexibility promoting a new range of possible applications. For example, the VUV spectral region is capable of characterizing lithographic materials for 157 nm photolithography. The VUV also provides increased sensitivity for thin layers (e.g., gate oxides or self-assembled monolayers) and allows investigation of high-energy electronic transitions. The infrared spectral region contains information about semiconductor doping concentration, phonon absorption, and molecular bond vibrational absorptions. In this work, we review the latest progress in SE wavelength coverage. Areas of significant application in both research and industrial fields will be surveyed, with emphasis on wavelength-specific information content.

  13. Structure-induced resonant tail-state regime absorption in polymer: fullerene bulk-heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Pfadler, Thomas; Kiel, Thomas; Stärk, Martin; Werra, Julia F. M.; Matyssek, Christian; Sommer, Daniel; Boneberg, Johannes; Busch, Kurt; Weickert, Jonas; Schmidt-Mende, Lukas

    2016-05-01

    In this work, we present resonant tail-state regime absorption enhanced organic photovoltaics. We combine periodically structured TiO2 bottom electrodes with P3HT-PCBM bulk-heterojunction solar cells in an inverted device configuration. The wavelength-scale patterns are transferred to the electron-selective bottom electrodes via direct laser interference patterning, a fast method compatible with roll-to-roll processing. Spectroscopic and optoelectronic device measurements suggest polarization-dependent absorption enhancement along with photocurrent generation unambiguously originating from the population of tail states. We discuss the effects underlying these absorption patterns with the help of electromagnetic simulations using the discontinuous Galerkin time domain method. For this, we focus on the total absorption spectra along with spatially resolved power loss densities. Our simulations stress the tunability of the absorption resonances towards arbitrary wavelength regions.

  14. Percutaneous absorption of Octopirox.

    PubMed

    Black, J G; Kamat, V B

    1988-01-01

    containing 1% Octopirox is 29,400, so that the possibility of systemic effects due to absorption through the skin is remote. PMID:3345970

  15. Spectroscopic measurement of radiation of high-pressure mercury discharge lamps

    SciTech Connect

    Fu Ling; Leutz, Ralf; Ries, Harald

    2005-06-15

    Compact size and high efficiency are important features for projection systems. As the most often used sources for projection optics, short arc lamps are characterized by their impressive economy and the ability to produce extremely bright light from small dimensional sources. In this contribution the old principle of back reflection towards the sources is applied to a high-pressure mercury discharge lamp with a reflector to improve the radiance of the source by 35% at a certain reduced solid angle. Increasing the optical thickness of sources is equivalent to reducing the total phase space (etendue) of emitted radiation by the same factor, which is very useful for compacting sources. In addition, by comparing the forward radiation and the back-reflected radiation obtained from spectroscopic measurements, we calculate the absorptivity, emissivity, absorption, and emission coefficients of the plasma of the arc lamp based on Kirchhoff's Law and Planck's equation which is necessary for determining its temperature and pressure.

  16. Calculation of equilibrium constants from multiwavelength spectroscopic data-I Mathematical considerations.

    PubMed

    Gampp, H; Maeder, M; Meyer, C J; Zuberbühler, A D

    1985-02-01

    Multiwavelength spectrophotometric and spectroscopic data in general contain considerably more information about complexation equilibria than potentiometric data do. With the construction of a fully automatic titration set-up built into a high-precision spectrophotometer, the problems related to the wider use of this method have shifted from the quality of the primary data to the complexity of their numerical treatment. Matrix algebra is used to show how these problems can be overcome. An algorithm is described for calculation of stability constants and absorption spectra, together with the associated standard errors, at a reasonable expense of computer time. Problems in finding the minimum in a multidimensional parameter space are reduced by elimination of the molar absorptivities from the algorithm for the iterative refinement. Numerical safety and speed of calculation are improved by use of analytical instead of numerical derivatives. The number of data to be fitted is decreased by principal-component analysis. PMID:18963802

  17. Spectroscopic Combustion Temperature Measurements: Effect Of Optical Depth In Black Liquor Recovery Boilers

    NASA Astrophysics Data System (ADS)

    Whetstone, J. R.; Charagundla, S. R.; Macek, A.; Semerjian, H. G.

    1988-11-01

    Results of a study directed toward using observed spectroscopic features for the measurement of temperature in the combustion zone of recovery boilers are described. Emissions of the potassium doublets at 404 and 766 nanometers (nm) have been observed in recovery boilers and temperature and self absorption effects on lines shapes have been modeled. Predicted emission line shapes are strongly dependent upon predicted concentration values of potassium. Proper selection of concentration ranges results in good qualitative agreement of predicted line shapes with those observed in boilers and laboratory flame experiments. These results indicate that the temperature dependence of potassium emissions is complicated by self-absorption effects which limit the optical pathlength over which emissions are practically observable. Temperature measurement may be feasible using pattern recognition methods coupled with algorithms based on an emission model and realistic estimates of the emitting species concentration.

  18. Resonant Absorption of Bessel Beams

    NASA Astrophysics Data System (ADS)

    Fan, J.; Parra, E.; Milchberg, H. M.

    1999-11-01

    We report the first observation of enhanced laser-plasma optical absorption in a subcritical density plasma resulting from spatial resonances, here in the laser breakdown of a gas with a Bessel beam. The enhancement in absorption is directly correlated to enhancements both in confinement of laser radiation to the plasma and in its heating. Under certain conditions, azimuthal asymmetry in the laser beam is essential for efficient gas breakdown. Simulations of this absorption consistently explain the experimental observations. This work is supported by the National Science Foundation (PHY-9515509) and the US Department of Energy (DEF G0297 ER 41039).

  19. A cryogenic circulating advective multi-pass absorption cell

    NASA Astrophysics Data System (ADS)

    Stockett, M. H.; Lawler, J. E.

    2012-03-01

    A novel absorption cell has been developed to enable a spectroscopic survey of a broad range of polycyclic aromatic hydrocarbons (PAH) under astrophysically relevant conditions and utilizing a synchrotron radiation continuum to test the still controversial hypothesis that these molecules or their ions could be carriers of the diffuse interstellar bands. The cryogenic circulating advective multi-pass absorption cell resembles a wind tunnel; molecules evaporated from a crucible or injected using a custom gas feedthrough are entrained in a laminar flow of cryogenically cooled buffer gas and advected into the path of the synchrotron beam. This system includes a multi-pass optical White cell enabling absorption path lengths of hundreds of meters and a detection sensitivity to molecular densities on the order of 107 cm-3. A capacitively coupled radio frequency dielectric barrier discharge provides ionized and metastable buffer gas atoms for ionizing the candidate molecules via charge exchange and the Penning effect. Stronger than expected clustering of PAH molecules has slowed efforts to record gas phase PAH spectra at cryogenic temperatures, though such clusters may play a role in other interstellar phenomena.

  20. High Velocity Absorption during Eta Car B's Periastron Passage

    NASA Technical Reports Server (NTRS)

    Nielsen, Krister E.; Groh, J. H.; Hillier, J.; Gull, Theodore R.; Owocki, S. P.; Okazaki, A. T.; Damineli, A.; Teodoro, M.; Weigelt, G.; Hartman, H.

    2010-01-01

    Eta Car is one of the most luminous massive stars in the Galaxy, with repeated eruptions with a 5.5 year periodicity. These events are caused by the periastron passage of a massive companion in an eccentric orbit. We report the VLT/CRIRES detection of a strong high-velocity, (<1900 km/s) , broad absorption wing in He I at 10833 A during the 2009.0 periastron passage. Previous observations during the 2003.5 event have shown evidence of such high-velocity absorption in the He I 10833 transition, allowing us to conclude that the high-velocity gas is crossing the line-of-sight toward Eta Car over a time period of approximately 2 months. Our analysis of HST/STlS archival data with observations of high velocity absorption in the ultraviolet Si IV and C IV resonance lines, confirm the presence of a high-velocity material during the spectroscopic low state. The observations provide direct detection of high-velocity material flowing from the wind-wind collision zone around the binary system, and we discuss the implications of the presence of high-velocity gas in Eta Car during periastron

  1. A cryogenic circulating advective multi-pass absorption cell

    SciTech Connect

    Stockett, M. H.; Lawler, J. E.

    2012-03-15

    A novel absorption cell has been developed to enable a spectroscopic survey of a broad range of polycyclic aromatic hydrocarbons (PAH) under astrophysically relevant conditions and utilizing a synchrotron radiation continuum to test the still controversial hypothesis that these molecules or their ions could be carriers of the diffuse interstellar bands. The cryogenic circulating advective multi-pass absorption cell resembles a wind tunnel; molecules evaporated from a crucible or injected using a custom gas feedthrough are entrained in a laminar flow of cryogenically cooled buffer gas and advected into the path of the synchrotron beam. This system includes a multi-pass optical White cell enabling absorption path lengths of hundreds of meters and a detection sensitivity to molecular densities on the order of 10{sup 7} cm{sup -3}. A capacitively coupled radio frequency dielectric barrier discharge provides ionized and metastable buffer gas atoms for ionizing the candidate molecules via charge exchange and the Penning effect. Stronger than expected clustering of PAH molecules has slowed efforts to record gas phase PAH spectra at cryogenic temperatures, though such clusters may play a role in other interstellar phenomena.

  2. A cryogenic circulating advective multi-pass absorption cell.

    PubMed

    Stockett, M H; Lawler, J E

    2012-03-01

    A novel absorption cell has been developed to enable a spectroscopic survey of a broad range of polycyclic aromatic hydrocarbons (PAH) under astrophysically relevant conditions and utilizing a synchrotron radiation continuum to test the still controversial hypothesis that these molecules or their ions could be carriers of the diffuse interstellar bands. The cryogenic circulating advective multi-pass absorption cell resembles a wind tunnel; molecules evaporated from a crucible or injected using a custom gas feedthrough are entrained in a laminar flow of cryogenically cooled buffer gas and advected into the path of the synchrotron beam. This system includes a multi-pass optical White cell enabling absorption path lengths of hundreds of meters and a detection sensitivity to molecular densities on the order of 10(7) cm(-3). A capacitively coupled radio frequency dielectric barrier discharge provides ionized and metastable buffer gas atoms for ionizing the candidate molecules via charge exchange and the Penning effect. Stronger than expected clustering of PAH molecules has slowed efforts to record gas phase PAH spectra at cryogenic temperatures, though such clusters may play a role in other interstellar phenomena. PMID:22462957

  3. Broadband rotor noise analyses

    NASA Technical Reports Server (NTRS)

    George, A. R.; Chou, S. T.

    1984-01-01

    The various mechanisms which generate broadband noise on a range of rotors studied include load fluctuations due to inflow turbulence, due to turbulent boundary layers passing the blades' trailing edges, and due to tip vortex formation. Existing analyses are used and extensions to them are developed to make more accurate predictions of rotor noise spectra and to determine which mechanisms are important in which circumstances. Calculations based on the various prediction methods in existing experiments were compared. The present analyses are adequate to predict the spectra from a wide variety of experiments on fans, full scale and model scale helicopter rotors, wind turbines, and propellers to within about 5 to 10 dB. Better knowledge of the inflow turbulence improves the accuracy of the predictions. Results indicate that inflow turbulence noise depends strongly on ambient conditions and dominates at low frequencies. Trailing edge noise and tip vortex noise are important at higher frequencies if inflow turbulence is weak. Boundary layer trailing edge noise, important, for large sized rotors, increases slowly with angle of attack but not as rapidly as tip vortex noise.

  4. Broadband rotor noise analyses

    NASA Astrophysics Data System (ADS)

    George, A. R.; Chou, S. T.

    1984-04-01

    The various mechanisms which generate broadband noise on a range of rotors studied include load fluctuations due to inflow turbulence, due to turbulent boundary layers passing the blades' trailing edges, and due to tip vortex formation. Existing analyses are used and extensions to them are developed to make more accurate predictions of rotor noise spectra and to determine which mechanisms are important in which circumstances. Calculations based on the various prediction methods in existing experiments were compared. The present analyses are adequate to predict the spectra from a wide variety of experiments on fans, full scale and model scale helicopter rotors, wind turbines, and propellers to within about 5 to 10 dB. Better knowledge of the inflow turbulence improves the accuracy of the predictions. Results indicate that inflow turbulence noise depends strongly on ambient conditions and dominates at low frequencies. Trailing edge noise and tip vortex noise are important at higher frequencies if inflow turbulence is weak. Boundary layer trailing edge noise, important, for large sized rotors, increases slowly with angle of attack but not as rapidly as tip vortex noise.

  5. Radiative heating and cooling in the middle and lower atmosphere of Venus and responses to atmospheric and spectroscopic parameter variations

    NASA Astrophysics Data System (ADS)

    Haus, R.; Kappel, D.; Arnold, G.

    2015-11-01

    A sophisticated radiative transfer model that considers absorption, emission, and multiple scattering by gaseous and particulate constituents over the broad spectral range 0.125-1000 μm is applied to calculate radiative fluxes and temperature change rates in the middle and lower atmosphere of Venus (0-100 km). Responses of these quantities to spectroscopic and atmospheric parameter variations are examined in great detail. Spectroscopic parameter studies include the definition of an optimum spectral grid for monochromatic calculations as well as comparisons for different input data with respect to spectral line databases, continuum absorption, line shape factors, and solar irradiance spectra. Atmospheric parameter studies are based on distinct variations of an initial model data set. Analyses of actual variations of the radiative energy budget using atmospheric features that have been recently retrieved from Venus Express data will be subject of a subsequent paper. The calculated cooling (heating) rates are very reliable at altitudes below 95 (85) km with maximum uncertainties of about 0.25 K/day. Heating uncertainties may reach 3-5 K/day at 100 km. Using equivalent Planck radiation as solar insolation source in place of measured spectra is not recommended. Cooling rates strongly respond to variations of atmospheric thermal structure, while heating rates are less sensitive. The influence of mesospheric minor gas variations is small, but may become more important near the cloud base and in case of episodic SO2 boosts. Responses to cloud mode 1 particle abundance changes are weak, but variations of other mode parameters (abundances, cloud top and base altitudes) may significantly alter radiative temperature change rates up to 50% in Venus' lower mesosphere and upper troposphere. A new model for the unknown UV absorber for two altitude domains is proposed. It is not directly linked to cloud particle modes and permits an investigation of radiative effects regardless of

  6. Spectroscopic, cyclic voltammetric and biological studies of transition metal complexes with mixed nitrogen-sulphur (NS) donor macrocyclic ligand derived from thiosemicarbazide

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Gupta, Lokesh Kumar; Sangeetika

    2005-11-01

    The complexation of new mixed thia-aza-oxa macrocycle viz., 2,12-dithio-5,9,14,18-tetraoxo-7,16-dithia-1,3,4,10,11,13-hexaazacyclooctadecane containing thiosemicarba-zone unit with a series of transition metals Co(II), Ni(II) and Cu(II) has been investigated, by different spectroscopic techniques. The structural features of the ligand have been studied by EI-mass, 1H NMR and IR spectral techniques. Elemental analyses, magnetic moment susceptibility, molar conductance, IR, electronic, and EPR spectral studies characterized the complexes. Electronic absorption and IR spectra of the complexes indicate octahedral geometry for chloro, nitrato, thiocyanato or acetato complexes. The dimeric and neutral nature of the sulphato complexes are confirmed from magnetic susceptibility and low conductance values. Electronic spectra suggests square-planar geometry for all sulphato complexes. The redox behaviour was studied by cyclic voltammetry, show metal-centered reduction processes for all complexes. The complexes of copper show both oxidation and reduction process. The redox potentials depend on the conformation of central atom in the macrocyclic complexes. Newly synthesized macrocyclic ligand and its transition metal complexes show markedly growth inhibitory activity against pathogenic bacterias and plant pathogenic fungi under study. Most of the complexes have higher activity than that of the metal free ligand.

  7. Stellar populations in spiral galaxies: broadband versus spectroscopic viewpoints

    NASA Astrophysics Data System (ADS)

    MacArthur, Lauren Anne

    2006-06-01

    This thesis addresses the stellar population content in the bulges and disks of spiral galaxies using broad-band and spectroscopic data. The results can be used to constrain models of galaxy formation in addition to establishing a comprehensive, model-independent, picture of colour and line-index gradients in spiral galaxies. Building upon my Masters study of structural parameters in spiral galaxies, I use the largest collection of multi-band (optical and IR) surface brightness profiles for face-on and moderately-tilted galaxies to extract radial colour profiles. The colour gradients are then translated into age and metallicity gradients by comparison with stellar population synthesis (SPS) models considering a range of star formation histories, including recent bursts. Based on their integrated light, we find that high surface brightness (SB) regions of galaxies formed their stars earlier than lower SB ones, or at a similar epoch but on shorter timescale. At a given SB level, the star formation histories are modulated by the overall potential of the galaxy such that brighter/higher rotational velocity galaxies formed earlier. This formation "down-sizing" implied by our results is inconsistent with current implementations of semi-analytic structure formation models. In order to alleviate concerns that our colour gradients could be affected by dust reddening, we designed a similar spectroscopic investigation and explored the dust sensitivity of absorption-line indices. The latter test makes use of the latest SPS, models incorporating a multi-component model for the line and continuum attenuation due to dust. For quiescent stellar populations (e.g. spheroids and globular clusters), dust extinction effects are small for most indices with the exception of the 4000 Å break. For models with current star formation, many indices may suffer from dust reddening and any departures depend on age, dust distribution, and the effective optical depth. However, a number of useful

  8. Stellar populations in spiral galaxies: Broadband versus spectroscopic viewpoints

    NASA Astrophysics Data System (ADS)

    MacArthur, Lauren Anne

    This thesis addresses the stellar population content in the bulges and disks of spiral galaxies using broad-band and spectroscopic data. The results can be used to constrain models of galaxy formation in addition to establishing a comprehensive, model-independent, picture of colour and line-index gradients in spiral galaxies. Building upon my Masters study of structural parameters in spiral galaxies, I use the largest collection of multi-band (optical and IR) surface brightness profiles for face-on and moderately-tilted galaxies to extract radial colour profiles. The colour gradients are then translated into age and metallicity gradients by comparison with stellar population synthesis (SPS) models considering a range of star formation histories, including recent bursts. Based on their integrated light, we find that high surface brightness (SB) regions of galaxies formed their stars earlier than lower SB ones, or at a similar epoch but on shorter timescale. At a given SB level, the star formation histories are modulated by the overall potential of the galaxy such that brighter/higher rotational velocity galaxies formed earlier. This formation "down-sizing" implied by our results is inconsistent with current implementations of semi-analytic structure formation models. In order to alleviate concerns that our colour gradients could be affected by dust reddening, we designed a similar spectroscopic investigation and explored the dust sensitivity of absorption-line indices. The latter test makes use of the latest SPS, models incorporating a multi-component model for the line and continuum attenuation due to dust. For quiescent stellar populations (e.g. spheroids and globular clusters), dust extinction effects are small for most indices with the exception of the 4000 Å break. For models with current star formation, many indices may suffer from dust reddening and any departures depend on age, dust distribution, and the effective optical depth. However, a number of useful

  9. Spectroscopic Evidence for Nonuniform Starspot Properties on II Pegasi

    NASA Technical Reports Server (NTRS)

    ONeal, Douglas; Saar, Steven H.; Neff, James E.

    1998-01-01

    We present spectroscopic evidence for Multiple Spot temperatures on the RS CVn star II Pegasi (HD 224085). We model the strengths of the 7055 and 8860 A TiO absorption bands in the spectrum of II Peg using weighted sums of inactive comparison spectra: a K star to represent the nonspotted photosphere and an M star to represent the spots. The best fit yields independent measurements of the starspot filling factor (f(sub s) and mean spot temperature (T(sub s)) averaged over the visible hemisphere of the star. During three-fourths of a rotation of II Peg in late 1996, we measure a constant f(sub s) approximately equals 55% +/- 5%. However, (T(sub s) varies from 3350 +/- 60 to 3550 +/- 70 K. We compute (T(sub s) for two simple models: (1) a star with two distinct spot temperatures, and (2) a star with different umbral/penumbral area ratios. The changing (T(sub s) correlates with emission strengths of H(alpha) and the Ca II infrared triplet in the sense that cooler (T(sub s) accompanies weaker emission. We explore possible implications of these results for the physical properties of the spots on II Peg and for stellar surface structure in general.

  10. II Peg: Spectroscopic Evidence for Multiple Starspot Temperatures

    NASA Astrophysics Data System (ADS)

    O'Neal, Douglas; Saar, Steven H.; Neff, James E. Neff

    We present spectroscopic evidence for multiple spot temperatures on the RS CVn star II Pegasi (HD 224085). We fit the strengths of the 7055 AAg and 8860 AAg TiO absorption bands in the spectrum of an active star using weighted sums of comparison spectra: the spectrum of an inactive K star to represent the non-spotted photosphere and the spectrum of an M star to represent the spots. We can thus independently measure starspot filling factor (fspot) and temperature (tspot). During 3/4 of a rotation of II Peg in Sept.-Oct. 1996, we measure fspot approximately constant at 55+/-5%. However, tspot varies from 3350 K to 3500 K. Since our method yields one derived tspot integrated over the visible hemisphere of the star, we present the results of simple models of a star with two distinct spot temperatures and compute the tspot we would derive in those cases. The changing tspot correlates with emission strengths of Hα and the Ca 2 infrared triplet, in the sense that cooler \\tspot accompanies weaker emission. We explore the consequences of these results for the physical properties of the spots on II Peg and for stellar surface structure in general.

  11. Spectroscopic Evidence for Nonuniform Starspot Properties on II Pegasi

    NASA Astrophysics Data System (ADS)

    O'Neal, Douglas; Saar, Steven H.; Neff, James E.

    1998-07-01

    We present spectroscopic evidence for multiple spot temperatures on the RS CVn star II Pegasi (HD 224085). We model the strengths of the 7055 and 8860 Å TiO absorption bands in the spectrum of II Peg using weighted sums of inactive comparison spectra: a K star to represent the nonspotted photosphere and an M star to represent the spots. The best fit yields independent measurements of the starspot filling factor (fS) and mean spot temperature () averaged over the visible hemisphere of the star. During three-fourths of a rotation of II Peg in late 1996, we measure a constant fS~55%+/-5%. However, varies from 3350+/-60 to 3550+/-70 K. We compute for two simple models: (1) a star with two distinct spot temperatures, and (2) a star with different umbral/penumbral area ratios. The changing correlates with emission strengths of Hα and the Ca II infrared triplet in the sense that cooler accompanies weaker emission. We explore possible implications of these results for the physical properties of the spots on II Peg and for stellar surface structure in general.

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

    PubMed Central

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

    2015-01-01

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

  13. Spectroscopic Search for Water Ice on Jovian Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Jewitt, D.

    2006-09-01

    We are conducting a systematic study of the Jovian Trojans using the Subaru 8-m, UKIRT 4-m and IRTF 3-m telescopes atop Mauna Kea, Hawaii. Theoretical models show that the Jovian Trojans formed beyond the snow-line and they may contain considerable amounts of water ice. We seek spectroscopic evidence for this pristine ice. Object (4709) Ennomos has a geometric albedo of 0.13+/-0.02, which is significantly above the mean Trojan albedo of 0.041+/- 0.002 (Fernandez et al., 2003). An intriguing possibility is that the albedo of Ennomos is high because a recent impact has coated part of the surface with freshly excavated ice. We obtained near-IR (0.8-2.5 micron) spectra of (4709) Ennomos in search of the 1.5 and 2.0 micron bands of water ice. Four other Trojans, (911) Agamemnon, (617) Patroclus, (1143) Odysseus and (2797) Teucer, were also observed. These objects have been reported to show possible weak absorptions at 1.7 and 2.3 micron respectively (Emery and Brown, 2003). All five targets appear spectrally featureless, even in our highest signal-to-noise ratio data. We present the data and a simple model consisting of mixtures of water ice and a spectrally featureless material, to quantify the limits to surface ice.

  14. Nonplanar property study of antifungal agent tolnaftate-spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Arul Dhas, D.; Hubert Joe, I.; Roy, S. D. D.; Balachandran, S.

    2011-09-01

    Vibrational analysis of the thionocarbamate fungicide tolnaftate which is antidermatophytic, antitrichophytic and antimycotic agent, primarily inhibits the ergosterol biosynthesis in the fungus, was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features, harmonic vibrational wavenumbers and torsional potential energy surface (PES) scan studies have been computed using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bonding orbital (NBO) analysis and optimized molecular structure show the clear evidence for electronic interaction of thionocarbamate group with aromatic ring. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C-C stretching mode in the phenyl and naphthalene ring provide evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity as a fungicide.

  15. Spectroscopic investigation of U, Np and Th in nuclear glasses

    NASA Astrophysics Data System (ADS)

    Calas, G.; Galoisy, L. V.; Petit-Maire, D.

    2011-12-01

    Vitrification of high-level radioactive waste in borosilicate glasses is currently used on an industrial scale in several countries. The fundamental properties of the waste forms are their chemical and mechanical durability against the forcing conditions represented by chemical alteration or internal/external irradiation. The waste immobilized in glass is composed of over 30 different nuclear fission and activation products, as well as minor actinides. The oxidation state and local atomic coordination of long-lived radionuclides are important parameters to understand the long-term evolution of the glass. We present an overview of the local structure around actinides in glasses similar to the French nuclear glass. X-Ray absorption spectroscopy has been used to probe the local environment around uranium, neptunium and thorium in these glasses. It is combined with with UV-visible spectroscopy, used to get selective information on the surrounding of U(IV), U(V) and U(VI) in glasses. Our spectroscopic data show that U, Np and Th occur in nuclear glasses in a peculiar surrounding showing significant differences with the crystal chemistry of these elements in crystalline compounds. Element speciation may be used as a pertinent parameter to follow the long-term stability of nuclear glasses, either under irradiation or during the alteration of the glass.

  16. Spectroscopic studies of anthracyclines: Structural characterization and in vitro tracking.

    PubMed

    Szafraniec, Ewelina; Majzner, Katarzyna; Farhane, Zeineb; Byrne, Hugh J; Lukawska, Malgorzata; Oszczapowicz, Irena; Chlopicki, Stefan; Baranska, Malgorzata

    2016-12-01

    A broad spectroscopic characterization, using ultraviolet-visible (UV-vis) and Fourier transform infrared absorption as well as Raman scattering, of two commonly used anthracyclines antibiotics (DOX) daunorubicin (DNR), their epimers (EDOX, EDNR) and ten selected analogs is presented. The paper serves as a comprehensive spectral library of UV-vis, IR and Raman spectra of anthracyclines in the solid state and in solution. The particular advantage of Raman spectroscopy for the measurement and analysis of individual antibiotics is demonstrated. Raman spectroscopy can be used to monitor the in vitro uptake and distribution of the drug in cells, using both 488nm and 785nm as source wavelengths, with submicrometer spatial resolution, although the cellular accumulation of the drug is different in each case. The high information content of Raman spectra allows studies of the drug-cell interactions, and so the method seems very suitable for monitoring drug uptake and mechanisms of interaction with cellular compartments at the subcellular level. PMID:27372511

  17. The Escaping Spectroscopic Binary θ^1 Ori E

    NASA Astrophysics Data System (ADS)

    Costero, R.; Allen, C.; Echevarría, J.; Georgiev, L.; Poveda, A.; Richer, M. G.

    2008-12-01

    θ^1 Ori E was found to be a double-lined spectroscopic binary by Costero et al. (2006). From the analysis of 86 Echelle spectra obtained during three years, in which the systems of both components are separable, we found that the nearly identical spectra are consistent with both stars being early- to mid-G subgiant stars, with strong Li I λ 6708Å absorption and moderate emission Ca II K lines. The latter features are indicative of the pre-main-sequence evolutionary stage of the binary and, hence, of its membership to the Orion Nebula Cluster (ONC). The radial velocitiy curves of both components yield a circular orbit (e < 10^{-3}) for the binary, with a period of 9.8952+/-0.0007 d. The semi-amplitudes of the curves are almost identical (84.4+/-1.0 km s^{-1}) and the systemic velocity is 34.3+/-0.7 km s^{-1}. The latter value is 8.3 km s^{-1} larger, by at least 3σ, than the average radial velocity of the ONC members, and very similar to the transverse velocity (relative to component A in the Trapezium) derived for the star by Allen et al. (2004) and Sánchez et al. (2008). We conclude that the binary is escaping from the cluster in which it was formed.

  18. Synthesis and Spectroscopic Properties of Neodymium doped Lead Chloride

    NASA Astrophysics Data System (ADS)

    Brown, Ei; Hommerich, Uwe; Trivedi, Sudhir; Zavada, John

    2006-11-01

    Recently, great attention has been focused on the development of new solid-state laser materials for potential near infrared (NIR) and middle-infrared (MIR) laser applications. Lead halide based materials have recently emerged as new non-hygroscopic laser hosts with low maximum phonon energies. The low-phonon energies lead to small non-radiative decay rates and efficient infrared emission from rare earth dopants. In this work, the crystal growth and infrared spectroscopic properties of Nd doped lead chloride, PbCl2, are discussed. Following optical pumping at 753 nm and 808 nm, Nd:PbCl2 exhibited several near-infrared emission bands between 800 and 1600 nm as well as a broad MIR emission centered at 5.1μm (^4I11/2->^4I9/2). The optical absorption, Judd-Ofelt (JO) parameters, and spontaneous emission probabilities of several Nd^3+ transitions have been measured and calculated. Based on the JO analysis, the radiative quantum efficiency of the 5.1μm emission was determined to be ˜13%. The peak emission cross-section of 5.1 μm emission was estimated to be ˜0.4x10-20cm^2, which is comparable to the other infrared laser transitions.

  19. Thermal, optical and spectroscopic characterizations of borate laser crystals

    SciTech Connect

    Chavoutier, M.; Jubera, V.; Veber, P.; Velazquez, M.; Viraphong, O.; Hejtmanek, J.; Decourt, R.; Debray, J.; Menaert, B.; Segonds, P.; Adamietz, F.; Rodriguez, V.; Manek-Hoenninger, I.; Fargues, A.; Descamps, D.; Garcia, A.

    2011-02-15

    The Yb-content Li{sub 6}Ln(BO{sub 3}){sub 3} (Ln: Gd, Y) solid solution has been investigated. Crystal growth has been successful for several compositions. A 22% molar content of ytterbium ions was determined by chemical analysis (ICP). Physical properties relevant to laser operation like mechanical hardness, thermal expansion and thermal conductivity were measured on single crystals. Optical measurements, including refractive index and low temperature spectroscopy, were also performed. Finally, the effect of the Y/Gd ratio is discussed. -- Graphical abstract: Several solid solutions of a rare earth borate were studied. The figure illustrates one of these single crystals obtained by Czochralski and shows thermal behaviour and absorption spectra at low temperature. Display Omitted Research highlights: {yields} We have grown by Czochralski method five Li{sub 6}Ln(BO{sub 3}){sub 3} (Ln=Y, Gd,Yb) single crystals. {yields} Chemical, physical and spectroscopic characteristics are reported. {yields} Data relevant to laser operation are listed.

  20. Spectroscopic Evidence for Gas Infall in GF 9-2

    NASA Astrophysics Data System (ADS)

    Furuya, Ray S.; Kitamura, Yoshimi; Shinnaga, Hiroko

    2009-02-01

    We present spectroscopic evidence for the infall motion of gas in the natal cloud core harboring an extremely young low-mass protostar GF 9-2. We previously discussed that the ongoing collapse of the GF 9-2 core has agreement with the Larson-Penston-Hunter (LPH) theoretical solution for the gravitational collapse of a core. To discuss the gas infall on firmer ground, we have carried out on-the-fly mapping observations of the HCO+ (1-0) line using the Nobeyama 45 m telescope equipped with the 25 Beam Array Receiver System. Furthermore, we observed the HCN (1-0) line with the 45 m telescope, and the HCO+ (3-2) line with the Caltech Submillimeter Observatory 10.4 m telescope. The optically thick HCO+ and HCN lines show blueskewed profiles whose deepest absorptions are seen at the peak velocity of optically thin lines, i.e., the systemic velocity of the cloud, indicating the presence of gas infall toward the central protostar. We compared the observed HCO+ line profiles with model ones by solving the radiative transfer in the core under LTE assumption. We found that the core gas has a constant infall velocity of ~0.5 km s-1 in the central region, leading to a mass accretion rate of 2.5 × 10-5 M sun yr-1. Consequently, we confirm that the gas infall in the GF 9-2 core is consistent with the LPH solution.