Science.gov

Sample records for field spectroscopic study

  1. Theoretical study of spectroscopic constants and anharmonic force field of SiF2.

    PubMed

    Li, Jing; Wang, Meishan; Yang, Chuanlu; Ma, Meizhong; Tong, Dianmin

    2015-05-01

    The equilibrium structure, spectroscopy constants, and anharmonic force field of SiF2 have been investigated at MP2, B3LYP, and B3PW91 levels of theory employing two basis sets cc-pVQZ and cc-pVTZ, respectively. The obtained equilibrium geometries, rotational constants, fundamental vibrational wave numbers, and centrifugal distortion constants are compared with the available experimental data or the previous theoretical values. The MP2/cc-pVQZ results of SiF2 are in excellent agreement with the available experimental data and afford a marked improvement over B3LYP/cc-pVQZ and B3PW91/cc-pVQZ in the calculation of spectroscopic constants and force constants of SiF2. The basis set enhancement beyond cc-pVQZ does not lead to a major improvement so that the cc-pVQZ basis set is sufficient for SiF2. The MP2/cc-pVQZ results may provide useful data for the spectroscopic experiment studies of SiF2. The used DFT method is also an advisable choice to study anharmonic force field of SiF2.

  2. The spectroscopic constants and anharmonic force field of AgSH: An ab initio study.

    PubMed

    Zhao, Yanliang; Wang, Meishan; Yang, Chuanlu; Ma, Xiaoguang; Zhu, Ziliang

    2016-07-05

    The equilibrium structure, spectroscopy constants, and anharmonic force field of silver hydrosulfide (AgSH) have been calculated at B3P86, B3PW91 and MP2 methods employing two basis sets, TZP and QZP, respectively. The calculated geometries, ground state rotational constants, harmonic vibrational wave numbers, and quartic and sextic centrifugal distortion constants are compared with the available experimental and theoretical data. The equilibrium rotational constants, fundamental frequencies, anharmonic constants, and vibration-rotation interaction constants, Coriolis coupling constants, cubic and quartic force constants are predicted. The calculated results show that the MP2/TZP results are in good agreement with experiment observation and are also an advisable choice to study the anharmonic force field of AgSH.

  3. Spectroscopic study of the electric field induced valence change of Fe-defect centers in SrTiO3.

    PubMed

    Lenser, Christian; Kalinko, Aleksandr; Kuzmin, Alexei; Berzins, Dzintars; Purans, Juris; Szot, Kristof; Waser, Rainer; Dittmann, Regina

    2011-12-14

    The electrochemical changes induced by an electric field in Fe-doped SrTiO(3) have been investigated by X-ray absorption spectroscopy (XANES and EXAFS), electron paramagnetic resonance (EPR) and Raman spectroscopy. A detailed study of the Fe dopant in the regions around the anode and cathode reveals new insights into the local structure and valence state of Fe in SrTiO(3) single crystals. The ab initio full multiple-scattering XANES calculations give an evidence of the oxygen vacancy presence in the first coordination shell of iron. Differences in the length and disorder of the Fe-O bonds as extracted from EXAFS are correlated to the unequivocal identification of the defect type by complementary spectroscopical techniques to identify the valence state of the Fe-dopant and the presence of the Fe - V(Ö) complexes. Through this combinatorial approach, novel structural information on Fe - V(Ö) complexes is provided by X-ray absorption spectroscopy, and the relation of Fe-O bond length, doping level and oxidation state in SrTi(1-x)Fe(x)O(3) is briefly discussed.

  4. Spectroscopic Study of Star-forming Galaxies in Filaments and the Field at z~0.5: Evidence for Environmental Dependence of Electron Density

    NASA Astrophysics Data System (ADS)

    Darvish, Behnam; Mobasher, Bahram; Sobral, David; Hemmati, Shoubaneh; Nayyeri, Hooshang; Shivaei, Irene

    2016-01-01

    We study the physical properties of a spectroscopic sample of 28 star-forming galaxies in a large filamentary structure in the COSMOS field at z~0.53, with spectroscopic data taken with the Keck/DEIMOS spectrograph, and compare them with a control sample of 30 field galaxies. We spectroscopically confirm the presence of a large galaxy filament (~ 8 Mpc), along which five confirmed X-ray groups exist. We show that within the uncertainties, the ionization parameter, equivalent width (EW), EW versus specific star-formation rate (sSFR) relation, EW versus stellar mass relation, line-of-sight velocity dispersion, dynamical mass, and stellar-to-dynamical mass ratio are similar for filament and field star-forming galaxies. However, we show that on average, filament star-forming galaxies are more metal-enriched (~ 0.1-0.15 dex), possibly due to the inflow of the already enriched intrafilamentary gas into filament galaxies. Moreover, we show that electron densities are significantly lower (a factor of ~17) in filament star-forming systems compared to those in the field, possibly because of a longer star-formation timescale for filament star-forming galaxies. Our results highlight the potential pre-processing role of galaxy filaments and intermediate-density environments on the evolution of galaxies, which has been highly underestimated.

  5. Spectroscopic Study of Star-forming Galaxies in Filaments and the Field at z ~ 0.5: Evidence for Environmental Dependence of Electron Density

    NASA Astrophysics Data System (ADS)

    Darvish, Behnam; Mobasher, Bahram; Sobral, David; Hemmati, Shoubaneh; Nayyeri, Hooshang; Shivaei, Irene

    2015-12-01

    We study the physical properties of a spectroscopic sample of 28 star-forming galaxies in a large filamentary structure in the COSMOS field at z ˜ 0.53, with spectroscopic data taken with the Keck/DEIMOS spectrograph, and compare them with a control sample of 30 field galaxies. We spectroscopically confirm the presence of a large galaxy filament (˜8 Mpc), along which five confirmed X-ray groups exist. We show that within the uncertainties, the ionization parameter, equivalent width (EW), EW versus specific star-formation rate (sSFR) relation, EW versus stellar mass relation, line-of-sight velocity dispersion, dynamical mass, and stellar-to-dynamical mass ratio are similar for filament and field star-forming galaxies. However, we show that, on average, filament star-forming galaxies are more metal enriched (˜0.1-0.15 dex), possibly owing to the inflow of the already-enriched intrafilamentary gas into filament galaxies. Moreover, we show that electron densities are significantly lower (a factor of ˜17) in filament star-forming systems compared to those in the field, possibly because of a longer star-formation timescale for filament star-forming galaxies. Our results highlight the potential pre-processing role of galaxy filaments and intermediate-density environments on the evolution of galaxies, which has been highly underestimated.

  6. SPECTROSCOPIC STUDY OF STAR-FORMING GALAXIES IN FILAMENTS AND THE FIELD AT z ∼ 0.5: EVIDENCE FOR ENVIRONMENTAL DEPENDENCE OF ELECTRON DENSITY

    SciTech Connect

    Darvish, Behnam; Mobasher, Bahram; Hemmati, Shoubaneh; Shivaei, Irene; Sobral, David; Nayyeri, Hooshang

    2015-12-01

    We study the physical properties of a spectroscopic sample of 28 star-forming galaxies in a large filamentary structure in the COSMOS field at z ∼ 0.53, with spectroscopic data taken with the Keck/DEIMOS spectrograph, and compare them with a control sample of 30 field galaxies. We spectroscopically confirm the presence of a large galaxy filament (∼8 Mpc), along which five confirmed X-ray groups exist. We show that within the uncertainties, the ionization parameter, equivalent width (EW), EW versus specific star-formation rate (sSFR) relation, EW versus stellar mass relation, line-of-sight velocity dispersion, dynamical mass, and stellar-to-dynamical mass ratio are similar for filament and field star-forming galaxies. However, we show that, on average, filament star-forming galaxies are more metal enriched (∼0.1–0.15 dex), possibly owing to the inflow of the already-enriched intrafilamentary gas into filament galaxies. Moreover, we show that electron densities are significantly lower (a factor of ∼17) in filament star-forming systems compared to those in the field, possibly because of a longer star-formation timescale for filament star-forming galaxies. Our results highlight the potential pre-processing role of galaxy filaments and intermediate-density environments on the evolution of galaxies, which has been highly underestimated.

  7. Study of InGaAs-based modulation doped field effect transistor structures using variable-angle spectroscopic ellipsometry

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Sieg, R. M.; Yao, H. D.; Snyder, P. G.; Woollam, J. A.; Pamulapati, J.; Bhattacharya, P. K.; Sekula-Moise, P. A.

    1991-01-01

    Variable-angle spectroscopic ellipsometry was used to estimate the thicknesses of all layers within the optical penetration depth of InGaAs-based modulation doped field effect transistor structures. Strained and unstrained InGaAs channels were made by molecular beam epitaxy (MBE) on InP substrates and by metal-organic chemical vapor deposition on GaAs substrates. In most cases, ellipsometrically determined thicknesses were within 10% of the growth-calibration results. The MBE-made InGaAs strained layers showed large strain effects, indicating a probable shift in the critical points of their dielectric function toward the InP lattice-matched concentration.

  8. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

    DOE PAGES

    Gaudet, J.; Maharaj, D. D.; Sala, G.; ...

    2015-10-27

    Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field Hamiltonian, eigenvalues and eigenvectors appropriate to the J=7/2 Yb3+ ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7. The precise ground state of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak “stuffing,” wherein a small proportion, approximately 2%, of the nonmagnetic Ti4+ sites are occupied by excess Yb3+. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb2Ti2O7, as well as a crushed singlemore » crystal with weak stuffing and an approximate composition of Yb2+xTi2–xO7+y with x = 0.046. All samples display three crystalline electric field transitions out of the ground state, and the ground state doublet itself is identified as primarily composed of mJ = ±1/2, as expected. However, stuffing at low temperatures in Yb2+xTi2–xO7+y induces a similar finite crystalline electric field lifetime as is induced in stoichiometric Yb2Ti2O7 by elevated temperature. In conclusion, an extended strain field exists about each local “stuffed” site, which produces a distribution of random crystalline electric field environments in the lightly stuffed Yb2+xTi2–xO7+y, in addition to producing a small fraction of Yb ions in defective environments with grossly different crystalline electric field eigenvalues and eigenvectors.« less

  9. Spectroscopic study of the HgMn star HD 49606: the quest for binarity, abundance stratifications and magnetic field

    NASA Astrophysics Data System (ADS)

    Catanzaro, G.; Giarrusso, M.; Leone, F.; Munari, M.; Scalia, C.; Sparacello, E.; Scuderi, S.

    2016-08-01

    In this paper, we present a multi-instrument analysis of the mercury-manganese star HD 49606. New spectroscopic observations have been obtained by us with Catania Astrophysical Observatory Spectropolarimeter (CAOS@OAC) and High Accuracy Radial Velocity Planet Searcher-North@Telescopio Nazionale Galileo (HARPS-N@TNG). Combining these observations with archive data coming from other instruments, we performed a comprehensive analysis of this star. We highlight the motion around the centre of mass of a binary system of SB1 type, and we calculate the fundamental parameters characterizing its orbit. We also speculate on the nature of the unseen component. From the fit of H β and H γ, we determined the effective temperature and gravity, while from a number of metal lines, we derive the rotational and microturbulent velocities. Regarding chemical composition, we found underabundances of helium, oxygen, magnesium, sulfur and nickel, solar composition for carbon and overabundances for all the other elements. In particular, mercury abundance is derived taking into account an isotopic mixture different from the terrestrial one. As to magnesium, silicon and phosphorus, we found a non-constant abundance with the optical depth, a result currently considered an evidence of stratification. Spectropolarimetric observations have been performed in the attempt to highlight the presence of a magnetic field, but no detection has been found.

  10. Spectroscopic Studies of Melanin.

    DTIC Science & Technology

    1986-01-01

    il), and leading to the production of oxygen radicals (12). Gallas (13) and Kozikowski et al. (14) have studied melanin fluorescence. As part of a...Raman scattering unobservable in aqueous solution by continuous wave techniques. As was also observed by Kozikowski et al. (14), the intrinsic...168B. 14. Kozikowski SD, Wolfram LJ, Alfano RR. Fluorescence spectroscopy of eumelanins. IEEE J Quant Electron 1984;OE20:1379-1382. 15. Slawinski J

  11. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Gaudet, J.; Maharaj, D. D.; Sala, G.; Kermarrec, E.; Ross, K. A.; Dabkowska, H. A.; Kolesnikov, A. I.; Granroth, G. E.; Gaulin, B. D.

    2015-10-01

    Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field (CEF) Hamiltonian, eigenvalues and eigenvectors appropriate to the J =7 /2 Yb3 + ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7 . The precise ground state (GS) of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak "stuffing," wherein a small proportion, ≈2 % , of the nonmagnetic Ti4 + sites are occupied by excess Yb3 +. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb2Ti2O7 , as well as a crushed single crystal with weak stuffing and an approximate composition of Yb2 +xTi2 -xO7 +y with x =0.046 . All samples display three CEF transitions out of the GS, and the GS doublet itself is identified as primarily composed of mJ=±1 /2 , as expected. However, stuffing at low temperatures in Yb2 +xTi2 -xO7 +y induces a similar finite CEF lifetime as is induced in stoichiometric Yb2Ti2O7 by elevated temperature. We conclude that an extended strain field exists about each local "stuffed" site, which produces a distribution of random CEF environments in the lightly stuffed Yb2 +xTi2 -xO7 +y , in addition to producing a small fraction of Yb ions in defective environments with grossly different CEF eigenvalues and eigenvectors.

  12. Nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1993-02-08

    The Nuclear Physics group at the University of Tennessee, Knoxville is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While our main emphasis is on experimental problems involving heavy-ion accelerators, we have maintained a strong collaboration with several theorists in order to best pursue the physics of our measurements. During the last year we have led several experiments at the Holifield Heavy Ion Research Facility and participated in others at Argonne National Laboratory. Also, we continue to be very active in the collaboration to study ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in a RHIC detector R D project. Our experimental work is in four broad areas: (1) the structure of nuclei at high angular momentum, (2) heavy-ion induced transfer reactions, (3) the structure of nuclei far from stability, and (4) ultra-relativistic heavy-ion physics. The results of studies in these particular areas will be described in this document in sections IIA, IIB, IIC, and IID, respectively. Areas (1), (3), and (4) concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Area (2) pursues the transfer of nucleons to states with high angular momentum, both to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions. An important component of our program is the strong emphasis on the theoretical aspects of nuclear structure and reactions.

  13. Spectroscopic (UV/VIS, Raman) and Electrophoresis Study of Cytosine-Guanine Oligonucleotide DNA Influenced by Magnetic Field

    PubMed Central

    Banihashemian, Seyedeh Maryam; Periasamy, Vengadesh; Boon Tong, Goh; Abdul Rahman, Saadah

    2016-01-01

    Studying the effect of a magnetic field on oligonucleotide DNA can provide a novel DNA manipulation technique for potential application in bioengineering and medicine. In this work, the optical and electrochemical response of a 100 bases oligonucleotides DNA, cytosine-guanine (CG100), is investigated via exposure to different magnetic fields (250, 500, 750, and 1000 mT). As a result of the optical response of CG100 to the magnetic field, the ultra-violet-visible spectrum indicated a slight variation in the band gap of CG100 of about 0.3 eV. Raman spectroscopy showed a significant deviation in hydrogen and phosphate bonds’ vibration after exposure to the magnetic field. Oligonucleotide DNA mobility was investigated in the external electric field using the gel electrophoresis technique, which revealed a small decrease in the migration of CG100 after exposure to the magnetic field. PMID:26999445

  14. Spectroscopic studies of individual plasmon resonant nanoparticles

    NASA Astrophysics Data System (ADS)

    Mock, Jack J.; Smith, David R.; Barbic, Mladen; Oldenburg, Steven J.; Schultz, David A.; Schultz, Sheldon

    2003-11-01

    We present a detailed description of the apparatus and techniques that we have utilized in our experimental study of individual plas on resonant nanoparticles,along with a brief description of some major results. The apparatus consists of a spectroscopic system combined with a modified darkfield microscope, which enables the user to sequentially select individual resonant nanostructures in the microscopic field of view for spectroscopic study. Plasmon resonant nanostructures scatter light elastically,and typically have very large scattering cross-sections at their resonant optical wavelengths. In general, spectra can be obtained with acquisition times between .1 to 30 seconds,and color images can be captured using consumer digital color cameras. Spheres,tetrahedrons,and pentagonal platelets were fabricated using colloidal chemistry techniques. To produce highly anisotropic structures such as nanorods and "barbells", templates were used. Many of these nanostructures have been individually spectroscopically characterized,and their spectra correlated with their shape and size as determined by transmission electron icroscope (TEM). The unique shape,size, composition,and dielectric surroundings of the individual plasmon resonant nanostructures determine their plasmon resonant behavior. We will show how the composition of the substrate on which the particles are immobilized and the dielectric of the surrounding medium have a significant effect on the plasmon resonance of the individual particles.

  15. Investigating magnetic activity in very stable stellar magnetic fields. Long-term photometric and spectroscopic study of the fully convective M4 dwarf V374 Pegasi

    NASA Astrophysics Data System (ADS)

    Vida, K.; Kriskovics, L.; Oláh, K.; Leitzinger, M.; Odert, P.; Kővári, Zs.; Korhonen, H.; Greimel, R.; Robb, R.; Csák, B.; Kovács, J.

    2016-05-01

    The ultrafast-rotating (Prot ≈ 0.44 d) fully convective single M4 dwarf V374 Peg is a well-known laboratory for studying intense stellar activity in a stable magnetic topology. As an observable proxy for the stellar magnetic field, we study the stability of the light curve, hence the spot configuration. We also measure the occurrence rate of flares and coronal mass ejections (CMEs). We have analysed spectroscopic observations, BV(RI)C photometry covering 5 yrs, and additional RC photometry that expands the temporal base over 16 yr. The light curve suggests an almost rigid-body rotation and a spot configuration that is stable over about 16 yrs, confirming the previous indications of a very stable magnetic field. We observed small changes on a nightly timescale and frequent flaring, including a possible sympathetic flare. The strongest flares seem to be more concentrated around the phase where the light curve indicates a smaller active region. Spectral data suggest a complex CME with falling-back and re-ejected material with a maximal projected velocity of ~675 km s-1. We observed a CME rate that is much lower than expected from extrapolations of the solar flare-CME relation to active stars. Tables of the photometry are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A11

  16. Neutron spectroscopic study of Crystal-field excitation in Yb2 (Ti2 - x Ybx) O7 -x/2

    NASA Astrophysics Data System (ADS)

    Gaudet, Jonathan; Maharaj, Dalini; Kermarrec, Edwin; Granroth, Garrett; Ross, Kate; Dabowska, Hanna; Gaulin, Bruce

    2015-03-01

    Among the rare-earth titanate pyrochlores, Yb2 Ti2O7 has attracted much attention as a potential realization of a quantum spin ice. While strong quantum effects are absent in classical spin ice compounds, they are thought to be significant in Yb2 Ti2O7 because of its effective spin S=1/2 and its XY spin anisotropy, quantities both determined by the Crystal-Electric Field (CEF) levels. However, a thorough neutron spectroscopy study of the CEF levels is still lacking. Here, we report time-of-flight inelastic neutron scattering measurements on Yb2 Ti2O7 . Our results lead to the unambiguous determination of the CEF levels, the ground-state wavefunction and therefore the nature of the spin anisotropy of the J=7/2 Yb3+ . A significant sample dependence in the low temperature heat capacity has been reported and attributed to an excess of Yb3+ (''stuffing'') in the structure. Our measurements, carried out on two well-characterized samples with different levels of stuffing, allow us to discuss the impact of such disorder on the CEF levels.

  17. SPECTROSCOPIC REDSHIFTS OF GALAXIES WITHIN THE FRONTIER FIELDS

    SciTech Connect

    Ebeling, Harald; Ma, Cheng-Jiun; Barrett, Elizabeth

    2014-04-01

    We present a catalog of 1921 spectroscopic redshifts measured in the fields of the massive galaxy clusters MACSJ0416.1–2403 (z = 0.397), MACSJ0717.5+3745 (z = 0.546), and MACSJ1149.5+2223 (z = 0.544), i.e., three of the four clusters selected by Space Telescope Science Institute as the targets of the Frontier Fields (FFs) initiative for studies of the distant Universe via gravitational lensing. Compiled in the course of the Massive Cluster Survey project (MACS) that detected the FF clusters, this catalog is provided to the community for three purposes: (1) to allow the identification of cluster members for studies of the galaxy population of these extreme systems, (2) to facilitate the removal of unlensed galaxies and thus reduce shear dilution in weak-lensing analyses, and (3) to improve the calibration of photometric redshifts based on both ground- and spacebased observations of the FF clusters.

  18. Micro-Spectroscopic Imaging and Characterization of Individually Identified Ice Nucleating Particles from a Case Field Study

    SciTech Connect

    Knopf, Daniel A.; Alpert, Peter A.; Wang, Bingbing; O'Brien, Rachel E.; Kelly, Stephen T.; Laskin, Alexander; Gilles, Mary K.; Moffet, Ryan C.

    2014-09-03

    The effect of anthropogenic and biogenic organic particles on atmospheric glaciation processes is poorly understood. We use an optical microscopy (OM) setup to identify the location of ice nuclei (IN) active in immersion freezing and deposition ice nucleation for temperatures of 200-273 K within a large population of particles sampled from an ambient environment. Applying multi-modal micro-spectroscopy methods we characterize the physicochemical properties of individual IN in particle populations collected in central California. Chemical composition and mixing state analysis of particle populations are performed to identify characteristic particle-type classes. All particle-types contained organic material. Particles in these samples take up water at subsaturated conditions, induce immersion freezing at subsaturated and saturated conditions above 226 K, and act as deposition IN below 226 K. The identified IN belong to the most common particle-type classes observed in the field samples: organic coated sea salt, Na-rich, and secondary and refractory carbonaceous particles. Based on these observations, we suggest that the IN are not always particles with unique chemical composition and exceptional ice nucleation propensity; rather, they are common particles in the ambient particle population. Thus, particle composition and morphology alone are insufficient to assess their potential to act as IN. The results suggest that particle-type abundance is also a crucial factor in determining the ice nucleation efficiency of specific IN types. These findings emphasize that ubiquitous organic particles can induce ice nucleation under atmospherically relevant conditions and that they may play an important role in atmospheric glaciation processes.

  19. The MASSIVE survey. I. A volume-limited integral-field spectroscopic study of the most massive early-type galaxies within 108 Mpc

    SciTech Connect

    Ma, Chung-Pei; Greene, Jenny E.; Murphy, Jeremy D.; McConnell, Nicholas; Janish, Ryan; Blakeslee, John P.; Thomas, Jens

    2014-11-10

    Massive early-type galaxies represent the modern day remnants of the earliest major star formation episodes in the history of the universe. These galaxies are central to our understanding of the evolution of cosmic structure, stellar populations, and supermassive black holes, but the details of their complex formation histories remain uncertain. To address this situation, we have initiated the MASSIVE Survey, a volume-limited, multi-wavelength, integral-field spectroscopic (IFS) and photometric survey of the structure and dynamics of the ∼100 most massive early-type galaxies within a distance of 108 Mpc. This survey probes a stellar mass range M* ≳ 10{sup 11.5} M {sub ☉} and diverse galaxy environments that have not been systematically studied to date. Our wide-field IFS data cover about two effective radii of individual galaxies, and for a subset of them, we are acquiring additional IFS observations on sub-arcsecond scales with adaptive optics. We are also acquiring deep K-band imaging to trace the extended halos of the galaxies and measure accurate total magnitudes. Dynamical orbit modeling of the combined data will allow us to simultaneously determine the stellar, black hole, and dark matter halo masses. The primary goals of the project are to constrain the black hole scaling relations at high masses, investigate systematically the stellar initial mass function and dark matter distribution in massive galaxies, and probe the late-time assembly of ellipticals through stellar population and kinematical gradients. In this paper, we describe the MASSIVE sample selection, discuss the distinct demographics and structural and environmental properties of the selected galaxies, and provide an overview of our basic observational program, science goals and early survey results.

  20. 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.

  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. Simulating electric field interactions with polar molecules using spectroscopic databases

    NASA Astrophysics Data System (ADS)

    Owens, Alec; Zak, Emil J.; Chubb, Katy L.; Yurchenko, Sergei N.; Tennyson, Jonathan; Yachmenev, Andrey

    2017-03-01

    Ro-vibrational Stark-associated phenomena of small polyatomic molecules are modelled using extensive spectroscopic data generated as part of the ExoMol project. The external field Hamiltonian is built from the computed ro-vibrational line list of the molecule in question. The Hamiltonian we propose is general and suitable for any polar molecule in the presence of an electric field. By exploiting precomputed data, the often prohibitively expensive computations associated with high accuracy simulations of molecule-field interactions are avoided. Applications to strong terahertz field-induced ro-vibrational dynamics of PH3 and NH3, and spontaneous emission data for optoelectrical Sisyphus cooling of H2CO and CH3Cl are discussed.

  3. Simulating electric field interactions with polar molecules using spectroscopic databases

    PubMed Central

    Owens, Alec; Zak, Emil J.; Chubb, Katy L.; Yurchenko, Sergei N.; Tennyson, Jonathan; Yachmenev, Andrey

    2017-01-01

    Ro-vibrational Stark-associated phenomena of small polyatomic molecules are modelled using extensive spectroscopic data generated as part of the ExoMol project. The external field Hamiltonian is built from the computed ro-vibrational line list of the molecule in question. The Hamiltonian we propose is general and suitable for any polar molecule in the presence of an electric field. By exploiting precomputed data, the often prohibitively expensive computations associated with high accuracy simulations of molecule-field interactions are avoided. Applications to strong terahertz field-induced ro-vibrational dynamics of PH3 and NH3, and spontaneous emission data for optoelectrical Sisyphus cooling of H2CO and CH3Cl are discussed. PMID:28338042

  4. Spectroscopic study of Mentha oils

    NASA Astrophysics Data System (ADS)

    Rai, A. K.; Singh, A. K.

    The visible fluorescence and excitation spectra of Mentha oils (Japanese mint oil, peppermint oil and spearmint oil) have been recorded. Different physical constants which are characteristic of the fluorescent molecules have been calculated for all three oils. Results reveal that the same group of organic compounds dominate in the oils of peppermint and spearmint, whereas some different compound is present in Japanese mint oil. It is also found that the fluorescence intensity of these oils is comparable to that of Rhodamine 6G dye in methanol solution. Our studies suggest that Mentha oils may be a useful lasing material in the 450-600 nm wavelength range.

  5. Nuclear spectroscopic studies. Progress report

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1994-02-18

    The Nuclear Physics group at UTK is involved in heavy-ion physics including both nuclear structure and reaction mechanisms. During the last year experimental work has been in 3 broad areas: structure of nuclei at high angular momentum, structure of nuclei far from stability, and ultra-relativistic heavy-ion physics. Results in these areas are described in this document under: properties of high-spin states, study of low-energy levels of nuclei far from stability, and high-energy heavy-ion physics (PHENIX, etc.). Another important component of the work is theoretical interpretation of experimental results (Joint Institute for Heavy Ion Research).

  6. Spectroscopic studies of the transplutonium elements

    SciTech Connect

    Carnall, W.T.; Conway, J.G.

    1983-01-01

    The challenging opportunity to develop insights into both atomic structure and the effects of bonding in compounds makes the study of actinide spectroscopy a particularly fruitful and exciting area of scientific endeavor. It is also the interpretation of f-element spectra that has stimulated the development of the most sophisticated theoretical modeling attempted for any elements in the periodic table. The unique nature of the spectra and the wealth of fine detail revealed make possible sensitive tests of both physical models and the results of Hartree-Fock type ab initio calculations. This paper focuses on the unique character of heavy actinide spectroscopy. It discusses how it differs from that of the lighter member of the series and what are the special properties that are manifested. Following the introduction, the paper covers the following: (1) the role of systematic studies and the relationships of heavy-actinide spectroscopy to ongoing spectroscopic investigations of the lighter members of the series; (2) atomic (free-ion) spectra which covers the present status of spectroscopic studies with transplutonium elements, and future needs and directions in atomic spectroscopy; (3) the spectra of actinide compounds which covers the present status and future directions of spectroscopic studies with compounds of the transplutonium elements; and other spectroscopies. 1 figure, 2 tables.

  7. Spectroscopic studies of the classical Cepheid ζ Gem: Analysis of the velocity field in the atmosphere and manifestation of the presence of a circumstellar envelope

    NASA Astrophysics Data System (ADS)

    Usenko, I. A.

    2016-06-01

    Based on five high-resolution spectra in the range 5625-7525 ˚A taken in 1995 and covering the ascending branch of the light curve from minimum to maximum, we have performed spectroscopic studies of the classical Cepheid ζ Gem. The atmospheric parameters and chemical composition of the Cepheid have been refined. The abundances of the key elements of the evolution of yellow supergiants are typical for an object that has passed the first dredge-up: a C underabundance, N, Na, and Al overabundances, and nearly solar O and Mg abundances. We have estimated [Fe/H] = +0.01 dex; the abundances of the remaining elements are also nearly solar. The metal absorption lines in all spectra show a clear asymmetry and the formation of secondary blue (B1 and B2) and red (R1 and R2) components, just as for the Cepheid X Sgr. The Hα absorption line is also split into blue (B) and red (R) components with different depths changing with pulsation phase. To analyze the velocity field in the atmosphere of ζ Gem, we have estimated the radial velocities from specially selected (with clear signatures of the B1, B2, R1, and R2 components) absorption lines (neutral atoms and ions) of metals (38 lines) and the B and R components of the Hα line. Analysis of these estimates has shown that their scatter is from -22 to 36 km s-1 for all pulsation phases but does not exceed 35-40 km s-1 for each individual phase, while it does not exceed 22 km s-1 for the Hα line components. The radial velocity estimates for the metal lines and their B1 and B2 components have been found to depend on the depths, suggesting the presence of a velocity gradient in the atmosphere. No significant difference in velocities between the atoms and ions of the metal lines is observed, i.e., there is no significant inhomogeneity in the upper atmospheric layers of the Cepheid. Since the averaged radial velocity estimates for the cores of the metal lines and their B1 and B2 components change with pulsation phase and coincide

  8. Nuclear spectroscopic studies. Progress report

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1993-02-08

    The Nuclear Physics group at the University of Tennessee, Knoxville is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While our main emphasis is on experimental problems involving heavy-ion accelerators, we have maintained a strong collaboration with several theorists in order to best pursue the physics of our measurements. During the last year we have led several experiments at the Holifield Heavy Ion Research Facility and participated in others at Argonne National Laboratory. Also, we continue to be very active in the collaboration to study ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in a RHIC detector R&D project. Our experimental work is in four broad areas: (1) the structure of nuclei at high angular momentum, (2) heavy-ion induced transfer reactions, (3) the structure of nuclei far from stability, and (4) ultra-relativistic heavy-ion physics. The results of studies in these particular areas will be described in this document in sections IIA, IIB, IIC, and IID, respectively. Areas (1), (3), and (4) concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Area (2) pursues the transfer of nucleons to states with high angular momentum, both to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions. An important component of our program is the strong emphasis on the theoretical aspects of nuclear structure and reactions.

  9. Spectroscopic study of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Curran, Seamus; Weldon, Declan N.; Blau, Werner J.; Zandbergen, Henny W.; Kastner, J.; Kuzmany, Hans

    1994-11-01

    We present a comprehensive experimental study of the vibrational spectra of nanotubes. There are two main lines observed in the Raman spectrum, one positioned at 1350 cm-1, the D line, and the other at 1580 cm-1, the G line. Both these lines are very similar to those seen with disordered graphite. The disorder induced D line is very weak compared to the G line which is indicative of high crystalline materials. The position and intensity of the D line strongly depends on the energy of the exciting laser. This dispersion effect was also observed for graphitic particles and may be explained by a photoselective resonance process of nanotubes with different sizes. There are two optically active modes in the Infrared spectrum for highly orientated polycrystalline graphite which are the E1u and A2u modes. The E1u mode is positioned at 1587 cm-1 while the A2u mode is positioned at 868 cm-1. The Infrared spectrum of the nanotubes shows both modes although the E1u mode is downshifted to 1575 cm-1.

  10. A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies

    ERIC Educational Resources Information Center

    Ramos, Carlos Henrique I.

    2004-01-01

    This article describes a practical experiment for teaching basic spectroscopic techniques to introduce the topic of protein conformational change to students in the field of molecular biology, biochemistry, or structural biology. The spectroscopic methods employed in the experiment are absorbance, for protein concentration measurements, and…

  11. NMR, MRI, and spectroscopic MRI in inhomogeneous fields

    DOEpatents

    Demas, Vasiliki; Pines, Alexander; Martin, Rachel W; Franck, John; Reimer, Jeffrey A

    2013-12-24

    A method for locally creating effectively homogeneous or "clean" magnetic field gradients (of high uniformity) for imaging (with NMR, MRI, or spectroscopic MRI) both in in-situ and ex-situ systems with high degrees of inhomogeneous field strength. THe method of imaging comprises: a) providing a functional approximation of an inhomogeneous static magnetic field strength B.sub.0({right arrow over (r)}) at a spatial position {right arrow over (r)}; b) providing a temporal functional approximation of {right arrow over (G)}.sub.shim(t) with i basis functions and j variables for each basis function, resulting in v.sub.ij variables; c) providing a measured value .OMEGA., which is an temporally accumulated dephasing due to the inhomogeneities of B.sub.0({right arrow over(r)}); and d) minimizing a difference in the local dephasing angle .phi.({right arrow over (r)},t)=.gamma..intg..sub.0.sup.t{square root over (|{right arrow over (B)}.sub.1({right arrow over (r)},t')|.sup.2+({right arrow over (r)}{right arrow over (G)}.sub.shimG.sub.shim(t')+.parallel.{right arrow over (B)}.sub.0({right arrow over (r)}).parallel..DELTA..omega.({right arrow over (r)},t'/.gamma/).sup.2)}dt'-.OMEGA. by varying the v.sub.ij variables to form a set of minimized v.sub.ij variables. The method requires calibration of the static fields prior to minimization, but may thereafter be implemented without such calibration, may be used in open or closed systems, and potentially portable systems.

  12. Fundamental spectroscopic studies of carbenes and hydrocarbon radicals

    SciTech Connect

    Gottlieb, C.A.; Thaddeus, P.

    1993-12-01

    Highly reactive carbenes and carbon-chain radicals are studied at millimeter wavelengths by observing their rotational spectra. The purpose is to provide definitive spectroscopic identification, accurate spectroscopic constants in the lowest vibrational states, and reliable structures of the key intermediates in reactions leading to aromatic hydrocarbons and soot particles in combustion.

  13. Preparation of cesium targets for gamma-spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; Basu, S. K.; Chanda, S.; Deb, P.; Eqbal, Md; Kundu, S.; Joseph, D.

    2000-11-01

    A procedure to prepare monoisotopic cesium compound targets for gamma-spectroscopic experiments is described. Using this procedure, uniform targets up to thicknesses of 0.6-1.2 mg/cm 2 were prepared and used for in-beam spectroscopic studies. The purity of the target was tested by energy dispersive X-ray fluorescence (EDXRF) measurements.

  14. A spectroscopic system for time- and space-resolved studies of impurities on the EXTRAP-T2 reversed field pinch

    NASA Astrophysics Data System (ADS)

    Sallander, J.

    1998-06-01

    The radial distribution of impurity line emission in the EXTRAP-T2 reversed field pinch (RFP) is studied with a five viewing chord, absolutely calibrated, spectrometer system. The light is analyzed with a single 0.5 m grating spectrometer. Different parts of the entrance slit are used for different channels. This arrangement makes it possible to use the system over a wide wavelength range, from 2500 to 6500 Å, without having to recalibrate the relative sensitivity for the different channels. The rather short plasma pulses of 10-15 ms require a high time resolution. The use of photomultiplier tubes provides a time resolution of 10 μs which is limited by the transient recorders used. The result is a robust, low-cost system that produces reliable measurements of the radial dependence of emission from a wide range of impurity ions.

  15. Subtask 1.11 -- Spectroscopic field screening of hazardous waste and toxic spills. Final report

    SciTech Connect

    Grisanti, A.A.

    1997-10-01

    Techniques for the field characterization of soil contamination due to spillage of hazardous waste or toxic chemicals are time-consuming and expensive. Thus more economical, less time-intensive methods are needed to facilitate rapid field screening of contaminated sites. The overall objective of this project is to study the feasibility of using an evanescent field absorbance sensor Fourier transform infrared spectroscopic sensor coupled with cone penetrometry as a field screening method. The specific objectives of this project are as follows: design an accessory for use with FT-IR that interfaces the spectrometer to a cone penetrometer; characterize the response of the FT-IR accessory to selected hydrocarbons in a laboratory-simulated field environment; and determine the ability of the FT-IR-CPT instrument to measure hydrocarbon contamination in soil by direct comparison with a reference method (e.g., Soxhlet extraction followed by gas chromatography) to quantify hydrocarbons from the same soil.

  16. Synergies between spectroscopic and time-series photometric surveys - LAMOST observations for the Kepler field and K2 fields

    NASA Astrophysics Data System (ADS)

    Fu, Jianning; De Cat, Peter; Smith, Martin

    2017-01-01

    Synergies between spectroscopic and time-series photometric surveys can provide valuable information for studies in Galactic archaeology. The Kepler satellite has provided unprecedented high duty-cycle, high-precision time-series photometric observations for a large number of stars. After a continuous monitoring of the Kepler field for 4 years, it started to observe K2 fields, which include multiple stellar populations, for about 80 days each. These observed fields are all good targets for Galactic archaeology, provided that spectroscopic observations can be made for hundreds of thousands of stars within these fields in a homogeneous way.In 2010, we initiated the LAMOST-Kepler project with the aim to collect low-resolution spectra for as many objects from the KIC10 catalogue as possible with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). This is a 4-m telescope equipped with 4,000 optical fibers covering a circular field of view with a diameter of 5 degrees on the sky. The observations since 2012 have resulted in 150,567 low-resolution spectra with the Signal-Noise-Ratio in r larger than 20. The stellar atmospheric parameters were derived and calibrated with the values determined from either high-resolution spectroscopy or asteroseismology. Since the end of 2015, five K2 fields have been observed with LAMOST and the qualified spectra were used to derive the stellar atmospheric parameters for 59,213 stars.In this presentation we introduce the LAMOST-Kepler project, whose data have a great potential for Galactic archaeology. It includes an update on the progress and a summary of the existing scientific works based on the data provided by this project.

  17. Spectroscopic studies of detonating heterogeneous explosives. [HNS

    SciTech Connect

    Renlund, A.M.; Trott, W.M.

    1985-01-01

    The experimental objectives of this work are to use real-time spectroscopic techniques, emission spectroscopy and Raman spectra to monitor chemical and physical changes in shock-loaded or detonating high explosive (HE) samples. The investigators hope to identify chemical species including any transient intermediates. Also, they wish to determine the physical state of the material when the reactions are taking place; measure the temperature and the pressure; and study the effect of different initiation parameters and bulk properties of the explosive material. This work is just part of the effort undertaken to gain information on the detailed chemistry involved in initiation and detonation. In summary, the investigators have obtained vibrational temperatures of some small radical products of detonation, which may correlate with the detonation temperature. They have also observed that NO/sub 2/ is an early product from detonating HNS and RDX, and that other electronically excited radical species such as CN(B) are formed in HNS detonations. In the Raman work, the single-pulse spectra could be obtained even in the severe environment of a detonation, and that the rate of removal of the parent molecule could be monitored. 2 refs., 6 figs.

  18. Fast Spectroscopic Imaging and Field Compensation Using Frequency Modulation at Ultra-High-Field

    NASA Astrophysics Data System (ADS)

    Jang, Albert Woo Ju

    The high energy phosphates (HEP) in the myocardium, which are critical to understanding the cardiac function in both normal and pathophysiologic states, can be assessed non-invasively in vivo using phosphorus-31 (31P) spectroscopy. Compared to proton, for the same volume and magnetic field strength, the available signal-to-noise (SNR) ratio of the HEP metabolites is orders of magnitude lower mainly due to its intrinsically low concentration. Hence, cardiac spectroscopy greatly benefits when performed at ultra-high-fields (UHF, ≥ 7 T), both in terms of increased SNR and increased spectroscopic resolution. However, at ultra-high-field strengths, complications arise from the RF transmit wavelength becoming comparable or smaller than the field-of-view (FOV), thus exhibiting wave-like behavior. Furthermore, even with the spectroscopic resolution afforded at UHF, measuring myocardial inorganic phosphate (Pi) is still a challenge and has been a major barrier in extracting the ATP turnover rate. Recently, an indirect way of extracting the ATP hydrolysis rate forgoing direct measurement of Pi was established. In this work, we combine this method with the T1 nom method to monitor the transmural distribution of forward creatine kinase reaction (kf,CK) and ATP hydrolysis rate (kr,ATPase) of the myocardium, effectively reducing data acquisition time by up to an order of magnitude. In addition, a new class of 2D FM pulses and multidimensional adiabatic pulses are presented, which can compensate for B1 inhomogeneity through its spatiotemporal properties. These pulses should be valuable for spectroscopic applications at ultra-high-fields.

  19. Spectroscopic studies of microwave plasmas containing hexamethyldisiloxane

    NASA Astrophysics Data System (ADS)

    Nave, A. S. C.; Mitschker, F.; Awakowicz, P.; Röpcke, J.

    2016-10-01

    Low-pressure microwave discharges containing hexamethyldisiloxane (HMDSO) with admixtures of oxygen and nitrogen, used for the deposition of silicon containing films, have been studied spectroscopically. Optical emission spectroscopy (OES) in the visible spectral range has been combined with infrared laser absorption spectroscopy (IRLAS). The experiments were carried out in order to analyze the dependence of plasma chemical phenomena on power and gas mixture at relatively low pressures, up to 50 Pa, and power values, up to 2 kW. The evolution of the concentration of the methyl radical, CH3, and of seven stable molecules, HMDSO, CH4, C2H2, C2H4, C2H6, CO and CO2, was monitored in the plasma processes by in situ IRLAS using tunable lead salt diode lasers (TDL) and external-cavity quantum cascade lasers (EC-QCL) as radiation sources. To achieve reliable values for the gas temperature inside and outside the plasma bulk as well as for the temperature in the plasma hot and colder zones, which are of great importance for calculation of species concentrations, three different methods based on emission and absorption spectroscopy data of N2, CH3 and CO have been used. In this approach line profile analysis has been combined with spectral simulation methods. The concentrations of the various species, which were found to be in the range between 1011 to 1015 cm-3, are in the focus of interest. The influence of the discharge parameters power, pressure and gas mixture on the molecular concentrations has been studied. To achieve further insight into general plasma chemical aspects the dissociation of the HMDSO precursor gas including its fragmentation and conversion to the reaction products was analyzed in detail.

  20. Transient full-field vibration measurement using spectroscopical stereo photogrammetry.

    PubMed

    Yue, Kaiduan; Li, Zhongke; Zhang, Ming; Chen, Shan

    2010-12-20

    Contrasted with other vibration measurement methods, a novel spectroscopical photogrammetric approach is proposed. Two colored light filters and a CCD color camera are used to achieve the function of two traditional cameras. Then a new calibration method is presented. It focuses on the vibrating object rather than the camera and has the advantage of more accuracy than traditional camera calibration. The test results have shown an accuracy of 0.02 mm.

  1. Spectroscopic study of the peculiar galaxy IC 883

    NASA Astrophysics Data System (ADS)

    Yakovleva, V. A.; Merkulova, O. A.; Karataeva, G. M.; Shalyapina, L. V.; Yablokova, N. V.; Burenkov, A. N.

    2016-04-01

    We analyze new optical spectroscopic observations obtained at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the SCORPIO focal reducer (in the modes of a Fabry-Perot interferometer (FPI) and long-slit spectroscopy) and the Multi-Pupil Fiber Spectrograph for the galaxy IC 883. We have confirmed that the main body of the galaxy rotates around its minor axis. The positions of the dynamical axes of the stellar and gaseous components have been found to differ by ~10°. The velocities in the SE tail do not correspond to the circular rotation around the galaxy's minor axis. This structure is probably a fragment of an unwound curved spiral arm. Regions with high velocity dispersions and peculiarities in the velocity fields have been found along the minor axis. Our study of the age and metallicity of the galaxy's stellar population has shown that the mean values of these parameters in the stellar disk, except for the central region ( r ≤ 5"), are ≈1 Gyr and ≈-0.4 dex, respectively. Both young (2-5 × 108 yr) and old (5-10 × 109 yr) stellar populations are present in the circumnuclear region. Our analysis of the spectroscopic data for the bright feature 8" south of the nucleus coincident in position with a compact X-ray source has shown that this is apparently a dwarf galaxy or a remnant of a companion galaxy. Our FPI observations in the Hα emission line and direct images have revealed a region of ionized gas that together with the already known structures along the minor axis forms a clumpy tidal structure of ionized gas pulled from the companion galaxy. The results of our study confirm the previously proposed hypothesis that the observed peculiar structures were formed by the merger of two galaxies. However, it can be said that IC 883 does not belong to the class of polar-ring galaxies.

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

    NASA Astrophysics Data System (ADS)

    Fishman, Randy S.

    2013-06-01

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

  3. Spectroscopic Studies of Double Beta Decays and MOON

    NASA Astrophysics Data System (ADS)

    Ejiri, H.

    2007-10-01

    This is a brief review of future spectroscopic experiments of neutrino-less double beta decays (0νββ) and the MOON (Mo Observatory Of Neutrinos) project. Spectroscopic 0νββ experiments of MOON, SuperNEMO and DCBA are planned to study Majorana masses in the quasi-degenerate (QD) and inverted mass hierarchy (IH) regions. MOON aims at 0νββ studies with the ν-mass sensitivities of 100-30 meV by means of a super ensemble of multi-layer modules, each being consist of a scintillator plate, two tracking detector planes and a thin ββ source film.

  4. SPECTROSCOPIC CONFIRMATION OF FAINT LYMAN BREAK GALAXIES NEAR REDSHIFT FIVE IN THE HUBBLE ULTRA DEEP FIELD

    SciTech Connect

    Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth; Grogin, Norman; Hathi, Nimish; Ryan, Russell; Straughn, Amber; Windhorst, Rogier A. Pirzkal, Norbert; Xu Chun; Koekemoer, Anton; Panagia, Nino; Dickinson, Mark; Ferreras, Ignacio; Gronwall, Caryl; Kuemmel, Martin; Walsh, Jeremy; Meurer, Gerhardt; Pasquali, Anna; Yan, H.-J.

    2009-05-20

    We present the faintest spectroscopically confirmed sample of z {approx} 5 Lyman break galaxies (LBGs) to date. The sample is based on slitless grism spectra of the Hubble Ultra Deep Field region from the Grism ACS Program for Extragalactic Science (GRAPES) and Probing Evolution and Reionization Spectroscopically (PEARS) projects, using the G800L grism on the Hubble Space Telescope Advanced Camera for Surveys. We report here confirmations of 39 galaxies, preselected as candidate LBGs using photometric selection criteria. We compare a 'traditional' V-dropout selection, based on the work of Giavalisco et al., to a more liberal one (with V - i > 0.9), and find that the traditional criteria are about 64% complete and 81% reliable. We also study the Ly{alpha} emission properties of our sample. We find that Ly{alpha} emission is detected in {approx}1/4 of the sample, and that the liberal V-dropout color selection includes {approx}55% of previously published line-selected Ly{alpha} sources. Finally, we examine our stacked two-dimensional spectra. We demonstrate that strong, spatially extended ({approx}1'') Ly{alpha} emission is not a generic property of these LBGs, but that a modest extension of the Ly{alpha} photosphere (compared to the starlight) may be present in those galaxies with prominent Ly{alpha} emission.

  5. Integrated Spectroscopic Studies of Anhydrous Sulfate Minerals

    NASA Technical Reports Server (NTRS)

    Lane, M. D.; Bishop, J. L.; Dyar, M. D.; Cloutis, E.; Forray, F. L.; Hiroi, T.

    2005-01-01

    Sulfates have been identified in Martian soils and bedrock and are emerging as an important indicator for aqueous activity on Mars. Sulfate minerals can form in a variety of low-temperature (evaporitic; chemical-weathering) and high-temperature (volcanic/fumarolic; hydrothermal) environments and their formational environments can range from alkaline to acidic. Although sulfates generally form in the presence of water, not all sulfates are hydrous or contain water in their structures. Many of these anhydrous sulfates (Dana group 28; Strunz class 67A) are minerals that form as accompanying phases to the main minerals in ore deposits or as replacement deposits in sedimentary rocks. However, some form from thermal decomposition of OH or H2O-bearing sulfates, such as from the reaction [1]: jarosite = yavapaiite + Fe2O3 + H2O. Where known, the stability fields of these minerals all suggest that they would be stable under martian surface conditions [2]. Thus, anhydrous sulfate minerals may contribute to martian surface mineralogy, so they must be well-represented in spectral libraries used for interpretation of the Martian surface. We present here the preliminary results of an integrated study of emittance, reflectance, and Mossbauer spectroscopy of a suite of wel-lcharacterized anhydrous sulfates.

  6. Design and realization of the IP control core in field controllers for LAMOST spectroscopes

    NASA Astrophysics Data System (ADS)

    Wang, Jianing; Han, Zhongyi; Zeng, Yizhong; Dai, Songxin; Hu, Zhongwen; Zhu, Yongtian; Wang, Lei; Hou, Yonghui

    2010-07-01

    The China-made telescope, LAMOST, consists of 16 spectroscopes to detect stellar spectra via 4000 optical fibers. In each spectroscope, many movable parts work in phase. Those parts are real-time controlled and managed by field controllers based on FPGA. This paper mainly introduces how to use DSP Builder module library in MATLAB / Simulink to construct the IP control core on FPGA chip. This method can also be used to design the control core of PID arithmetic, to carry out arithmetic simulation and generate VHDL language file, as well as to integrate it into SOPC developing environment so as to repeatedly use. In this way, the design period of the control system may be shortened and design process simplified. Finally due to the reversibility and programmability of the IP control core ,a system on a chip for field controllers of spectroscope is realized, which meets astronomical control requirements, providing an effective scheme for embedded system in astronomical instrument applications.

  7. On-line separator for {gamma}-spectroscopic studies

    SciTech Connect

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Kabachenko, A. P.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.; Dorvaux, O.; Hauschild, K.; Korichi, A.; Lopez-Martens, A.

    2008-05-12

    We report about R and D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized U400R FLNR cyclotron and which will allow to realize new possibilities of the JINR-IN2P3 collaboration project GABRIELA.

  8. On-line separator for γ-spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Dorvaux, O.; Hauschild, K.; Kabachenko, A. P.; Korichi, A.; Lopez-Martens, A.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.

    2008-05-01

    We report about R&D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized U400R FLNR cyclotron and which will allow to realize new possibilities of the JINR-IN2P3 collaboration project GABRIELA [1, 2].

  9. High temperature furnace system for vacuum ultraviolet spectroscopic studies.

    PubMed

    Brown, C M; Naber, R H; Tilford, S G; Ginter, M L

    1973-08-01

    An improved furnace system for use in vacuum ultraviolet spectroscopic studies of atomic and molecular species stable at high temperatures (800-2500 degrees C) is described in detail. A new and improved high resolution spectrum of Mg I and several impurity spectra produced in the furnace are presented.

  10. ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description

    NASA Astrophysics Data System (ADS)

    Walter, Fabian; Decarli, Roberto; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Ivison, R. J.; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Anguita, Timo; Assef, Roberto; Bacon, Roland; Bauer, Franz; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Dickinson, Mark; Elbaz, David; Gónzalez-López, Jorge; Ibar, Edo; Inami, Hanae; Infante, Leopoldo; Hodge, Jacqueline; Karim, Alex; Le Fevre, Olivier; Magnelli, Benjamin; Neri, Roberto; Oesch, Pascal; Ota, Kazuaki; Popping, Gergö; Rix, Hans-Walter; Sargent, Mark; Sheth, Kartik; van der Wel, Arjen; van der Werf, Paul; Wagg, Jeff

    2016-12-01

    We present the rationale for and the observational description of ASPECS: the ALMA SPECtroscopic Survey in the Hubble Ultra-Deep Field (UDF), the cosmological deep field that has the deepest multi-wavelength data available. Our overarching goal is to obtain an unbiased census of molecular gas and dust continuum emission in high-redshift (z > 0.5) galaxies. The ˜1‧ region covered within the UDF was chosen to overlap with the deepest available imaging from the Hubble Space Telescope. Our ALMA observations consist of full frequency scans in band 3 (84-115 GHz) and band 6 (212-272 GHz) at approximately uniform line sensitivity ({L}{CO}\\prime ˜ 2 × 109 K km s-1 pc2), and continuum noise levels of 3.8 μJy beam-1 and 12.7 μJy beam-1, respectively. The molecular surveys cover the different rotational transitions of the CO molecule, leading to essentially full redshift coverage. The [C ii] emission line is also covered at redshifts 6.0\\lt z\\lt 8.0. We present a customized algorithm to identify line candidates in the molecular line scans and quantify our ability to recover artificial sources from our data. Based on whether multiple CO lines are detected, and whether optical spectroscopic redshifts as well as optical counterparts exist, we constrain the most likely line identification. We report 10 (11) CO line candidates in the 3 mm (1 mm) band, and our statistical analysis shows that <4 of these (in each band) are likely spurious. Less than one-third of the total CO flux in the low-J CO line candidates are from sources that are not associated with an optical/NIR counterpart. We also present continuum maps of both the band 3 and band 6 observations. The data presented here form the basis of a number of dedicated studies that are presented in subsequent papers.

  11. Spatiotemporal Characterization of Extracellular Matrix Microstructures in Engineered Tissue: A Whole-Field Spectroscopic Imaging Approach.

    PubMed

    Xu, Zhengbin; Ozcelikkale, Altug; Kim, Young L; Han, Bumsoo

    2013-02-01

    Quality and functionality of engineered tissues are closely related to the microstructures and integrity of their extracellular matrix (ECM). However, currently available methods for characterizing ECM structures are often labor-intensive, destructive, and limited to a small fraction of the total area. These methods are also inappropriate for assessing temporal variations in ECM structures. In this study, to overcome these limitations and challenges, we propose an elastic light scattering approach to spatiotemporally assess ECM microstructures in a relatively large area in a nondestructive manner. To demonstrate its feasibility, we analyze spectroscopic imaging data obtained from acellular collagen scaffolds and dermal equivalents as model ECM structures. For spatial characterization, acellular scaffolds are examined after a freeze/thaw process mimicking a cryopreservation procedure to quantify freezing-induced structural changes in the collagen matrix. We further analyze spatial and temporal changes in ECM structures during cell-driven compaction in dermal equivalents. The results show that spectral dependence of light elastically backscattered from engineered tissue is sensitively associated with alterations in ECM microstructures. In particular, a spectral decay rate over the wavelength can serve as an indicator for the pore size changes in ECM structures, which are at nanometer scale. A decrease in the spectral decay rate suggests enlarged pore sizes of ECM structures. The combination of this approach with a whole-field imaging platform further allows visualization of spatial heterogeneity of EMC microstructures in engineered tissues. This demonstrates the feasibility of the proposed method that nano- and micrometer scale alteration of the ECM structure can be detected and visualized at a whole-field level. Thus, we envision that this spectroscopic imaging approach could potentially serve as an effective characterization tool to nondestructively, accurately

  12. Inhibition of urinary calculi -- a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia; Govani, Jayesh; Durrer, William; Reza, Layra; Pinales, Luis

    2008-10-01

    Although a considerable number of investigations have already been undertaken and many causes such as life habits, metabolic disorders, and genetic factors have been noted as sources that accelerate calculi depositions and aggregations, there are still plenty of unanswered questions regarding efficient inhibition and treatment mechanisms. Thus, in an attempt to acquire more insights, we propose here a detailed scientific study of kidney stone formation and growth inhibition based on a traditional medicine approach with Rotula Aquatica Lour (RAL) herbal extracts. A simplified single diffusion gel growth technique was used for synthesizing the samples for the present study. The unexpected Zn presence in the sample with RAL inhibitor, as revealed by XPS measurements, explains the inhibition process and the dramatic reflectance of the incident light observed in the infrared transmission studies. Raman data demonstrate potential binding of the inhibitor with the oxygen of the kidney stone. Photoluminescence results corroborate to provide additional evidence of Zn-related inhibition.

  13. Spectroscopic analysis of bones for forensic studies

    NASA Astrophysics Data System (ADS)

    Tofanelli, Mirko; Pardini, Lorenzo; Borrini, Matteo; Bartoli, Fulvio; Bacci, Alessandra; D'Ulivo, Alessandro; Pitzalis, Emanuela; Mascherpa, Marco Carlo; Legnaioli, Stefano; Lorenzetti, Giulia; Pagnotta, Stefano; de Holanda Cavalcanti, Gildo; Lezzerini, Marco; Palleschi, Vincenzo

    2014-09-01

    The elemental analysis of human bones can give information about the dietary habits of the deceased, especially in the last years of their lives, which can be useful for forensic studies. The most important requirement that must be satisfied for this kind of analysis is that the concentrations of analyzed elements are the same as ante mortem. In this work, a set of bones was analyzed using Laser-Induced Breakdown Spectroscopy (LIBS) and validated using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), in order to compare those two techniques and to investigate the effect of possible alterations in the elemental concentrations' proportion resulting from the treatment usually applied for preparing the bones for traditional forensic analysis. The possibility that elemental concentrations' changes would occur after accidental or intentional burning of the bones was also studied.

  14. Integrated Spectroscopic Studies of Hydrous Sulfate Minerals

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.; Lane, M. D.; Bishop, J. L.; OConnor, V.; Cloutis, E.; Hiroi, T.

    2005-01-01

    Sulfate minerals have been identified in Martian meteorites and on Mars using a suite of instruments aboard the MER rovers. These results have confirmed previous groundbased observations and orbital measurements that suggested their presence. The orbiting OMEGA instrument on Mars Express is also finding evidence for sulfate. In order to better interpret remote-sensing data, we present here the results of a coordinated visible/near infrared (VNIR) reflectance, Moussbauer (MB), and thermal emittance study of wellcharacterized hydrous sulfate minerals.

  15. Progress report on nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1994-02-18

    The Nuclear Physics group at the University of Tennessee, Knoxville (UTK) is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While the main emphasis is on experimental problems, the authors have maintained a strong collaboration with several theorists in order to best pursue the physics of their measurements. During the last year they have had several experiments at the ATLAS at Argonne National Laboratory, the GAMMASPHERE at the LBL 88 Cyclotron, and with the NORDBALL at the Niels Bohr Institute Tandem. Also, they continue to be very active in the WA93/98 collaboration studying ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in the PHENIX Collaboration at the RHIC accelerator under construction at Brookhaven National Laboratory. During the last year their experimental work has been in three broad areas: (1) the structure of nuclei at high angular momentum, (2) the structure of nuclei far from stability, and (3) ultra-relativistic heavy-ion physics. The results of studies in these particular areas are described in this document. These studies concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Another area of research is heavy-ion-induced transfer reactions, which utilize the transfer of nucleons to states with high angular momentum to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions.

  16. Progress report on nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Riedinger, L.L.; Sorensen, S.P.

    1996-01-16

    The experimental program in nuclear physics at the University of Tennessee, Knoxville, is led by Professors Carrol Bingham, Lee Riedinger, and Soren Sorenseni who respectively lead the studies of the exotic decay modes of nuclei far from stability, the program of high-spin research, and our effort in relativistic heavy-ion physics. Over the years, this broad program of research has been successful partially because of the shared University resources applied to this group effort. The proximity of the Oak Ridge National Laboratory has allowed us to build extremely strong programs of joint research, and in addition to play an important leadership role in the Joint Institute for Heavy Ion Research (JIHIR). Our experimental program is also very closely linked with those at other national laboratories: Argonne (collaborations involving the Fragment Mass Analyzer (FMA) and {gamma}-ray arrays), Brookhaven (the RHIC and Phenix projects), and Berkeley (GAMMASPHERE). We have worked closely with a variety of university groups in the last three years, especially those in the UNISOR and now UNIRIB collaborations. And, in all aspects of our program, we have maintained close collaborations with theorists, both to inspire the most exciting experiments to perform and to extract the pertinent physics from the results. The specific areas discussed in this report are: properties of high-spin states; study of low-energy levels of nuclei far from stability; and high energy heavy-ion physics.

  17. Spectroscopic studies of silver boro tellurite glasses

    SciTech Connect

    Kumar, E. Ramesh Kumari, K. Rajani Rao, B. Appa Bhikshamaiah, G.

    2014-04-24

    The FTIR absorption and Raman scattering studies were used to obtain the structural information of AgI−Ag{sub 2}O−[(1−x)B{sub 2}O{sub 3}−xTeO{sub 2}] (x=0 to 1 mol% in steps of 0.2) glasses. The glassy nature of the compounds has been confirmed by X-ray diffraction. FTIR and Raman spectra were recorded for all samples at room temperature. FTIR spectra which provides the information about the change in bond structure of the glasses. Raman spectra provide the effect of TeO{sub 2} on SBT glass system is that as increasing the concentration of TeO{sub 2} the band intensity at 707 cm{sup −1} increase.

  18. Spectroscopic studies of silver boro tellurite glasses

    NASA Astrophysics Data System (ADS)

    Kumar, E. Ramesh; Kumari, K. Rajani; Rao, B. Appa; Bhikshamaiah, G.

    2014-04-01

    The FTIR absorption and Raman scattering studies were used to obtain the structural information of AgI-Ag2O-[(1-x)B2O3-xTeO2] (x=0 to 1 mol% in steps of 0.2) glasses. The glassy nature of the compounds has been confirmed by X-ray diffraction. FTIR and Raman spectra were recorded for all samples at room temperature. FTIR spectra which provides the information about the change in bond structure of the glasses. Raman spectra provide the effect of TeO2 on SBT glass system is that as increasing the concentration of TeO2 the band intensity at 707 cm-1 increase.

  19. Terahertz spectroscopic study of benzodiazepine sedative hypnotics

    NASA Astrophysics Data System (ADS)

    Deng, Fusheng; Shen, Jingling; Wang, Xianfeng

    2011-08-01

    Terahertz time domain spectroscopy (THz-TDS) is used to the pure active ingredient of three benzodiazepine sedative hypnotics with similar molecular structure. The absorption spectra of them are studied in the range of 0.2~2.6THz. Based on the experiment, the theoretical simulation results of diazepam, nitrazepam and clonazepam are got by the Gaussian03 package of DFT/B3LYP/6-31G* method in single-molecule models. The experimental results show that even if the molecular structure and medicine property of them are similar, the accurate identification of them can still be done with their characteristic absorption spectra. Theoretical simulation results are well consistent with the experimental results. It demonstrates that absorption peaks of them in THz range mainly come from intra-molecular forces and are less affected by the intermolecular interaction and crystal effects.ô

  20. Spectroscopic studies near the proton drip line

    SciTech Connect

    Toth, K.S. ); Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A. ); Robertson, J.D. )

    1990-01-01

    We have investigated nuclei close to the proton drip line by using heavy-ion fusion reactions to produce extremely neutron-deficient nuclides. Their nuclear decay properties were studied by using on-line isotope separators at Oak Ridge (UNISOR) and Berkeley (OASIS), the Oak Ridge National Laboratory velocity filter, and a fast helium-gas-jet transport system at Lawrence Berkeley Laboratory 88-Inch Cyclotron. Many isotopes, isomers, and {beta}-delayed-proton and {alpha}-particle emitters were discovered. This contribution summarizes three topics that are part of our overall program: decay rates of even-even {alpha}-particle emitters, mass excesses of {sup 181}Pb, {sup 182}Pb, and {sup 183}Pb, and {beta}-delayed proton emitters near N = 82. 14 refs., 6 figs.

  1. Spectroscopic study of acetylene and hydrogen cyanide

    NASA Astrophysics Data System (ADS)

    Rozario, Hoimonti Immaculata

    High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213-333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole--quadrupole and pairwise atom--atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results. We have studied the line intensities of the 1vl 20←0v120 band system from the HCN emission spectrum. The infrared emission spectrum of H12C 14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters.

  2. Spectroscopic Studies of Molecular Systems relevant in Astrobiology

    NASA Astrophysics Data System (ADS)

    Fornaro, Teresa

    2016-01-01

    In the Astrobiology context, the study of the physico-chemical interactions involving "building blocks of life" in plausible prebiotic and space-like conditions is fundamental to shed light on the processes that led to emergence of life on Earth as well as to molecular chemical evolution in space. In this PhD Thesis, such issues have been addressed both experimentally and computationally by employing vibrational spectroscopy, which has shown to be an effective tool to investigate the variety of intermolecular interactions that play a key role in self-assembling mechanisms of nucleic acid components and their binding to mineral surfaces. In particular, in order to dissect the contributions of the different interactions to the overall spectroscopic signals and shed light on the intricate experimental data, feasible computational protocols have been developed for the characterization of the spectroscopic properties of such complex systems. This study has been carried out through a multi-step strategy, starting the investigation from the spectroscopic properties of the isolated nucleobases, then studying the perturbation induced by the interaction with another molecule (molecular dimers), towards condensed phases like the molecular solid, up to the case of nucleic acid components adsorbed on minerals. A proper modeling of these weakly bound molecular systems has required, firstly, a validation of dispersion-corrected Density Functional Theory methods for simulating anharmonic vibrational properties. The isolated nucleobases and some of their dimers have been used as benchmark set for identifying a general, reliable and effective computational procedure based on fully anharmonic quantum mechanical computations of the vibrational wavenumbers and infrared intensities within the generalized second order vibrational perturbation theory (GVPT2) approach, combined with the cost-effective dispersion-corrected density functional B3LYP-D3, in conjunction with basis sets of

  3. Interactions of Isophorone Derivatives with DNA: Spectroscopic Studies

    PubMed Central

    Deiana, Marco; Matczyszyn, Katarzyna; Massin, Julien; Olesiak-Banska, Joanna; Andraud, Chantal; Samoc, Marek

    2015-01-01

    Interactions of three new isophorone derivatives, Isoa Isob and Isoc with salmon testes DNA have been investigated using UV-Vis, fluorescence and circular dichroism spectroscopic methods. All the studied compounds interact with DNA through intercalative binding mode. The stoichiometry of the isophorone/DNA adducts was found to be 1:1. The fluorescence quenching data revealed a binding interaction with the base pairs of DNA. The CD data indicate that all the investigated isophorones induce DNA modifications. PMID:26069963

  4. Spectroscopic Studies of Nearby Cool Stars: The DUNES Sample

    NASA Astrophysics Data System (ADS)

    Maldonado, J.; Martínez-Arnáiz, R. M.; Eiroa, C.; Montes, D.

    2009-02-01

    At the Universities of Madrid we are carrying out a systematic analysis of the spectroscopic properties of the nearby (d<25 pc), late-type stellar population with the aim of contributing to the knowledge of the stellar formation history in the solar neighbourhood. Part of our sample will be observed by DUNES, a Herschel OTKP aiming at detecting and studying cold, faint dust disks around nearby stars. In this contribution we present some preliminary results of the kinematics of the DUNES sample.

  5. Spectroscopic Studies of Nearby Cool Stars: The DUNES Sample

    NASA Astrophysics Data System (ADS)

    Maldonado, J.; Martinez-Arnáiz, R. M.; Eiroa, C.; Montes, D.

    At the universities of Madrid we are carrying out a systematic analysis of the spectroscopic properties of the nearby (d<25pc), late-type stellar population with the aim of contributing to the knowledge of the stellar formation history in the solar neighbourhood. Part of our sample will be observed by DUNES, a Herschel OTKP aiming at detecting and studying cold, faint dust disks around nearby stars. In this contribution we present some preliminary results on the kinematics of the DUNES sample.

  6. Photoelectron spectroscopic studies of 5-halouracil anions

    SciTech Connect

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Bowen, Kit H.; Sevilla, Michael D.; Rak, Janusz

    2011-01-07

    The parent negative ions of 5-chlorouracil, UCl{sup -} and 5-fluorouracil, UF{sup -} have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl{sup -} and UF{sup -} and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr{sup -}, we did not observe it, the mass spectrum exhibiting only Br{sup -} fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  7. Photoelectron spectroscopic studies of 5-halouracil anions

    NASA Astrophysics Data System (ADS)

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Sevilla, Michael D.; Rak, Janusz; Bowen, Kit H.

    2011-01-01

    The parent negative ions of 5-chlorouracil, UCl- and 5-fluorouracil, UF- have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl- and UF- and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr-, we did not observe it, the mass spectrum exhibiting only Br- fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  8. Spectroscopic study of biologically active glasses

    NASA Astrophysics Data System (ADS)

    Szumera, M.; Wacławska, I.; Mozgawa, W.; Sitarz, M.

    2005-06-01

    It is known that the chemical activity phenomenon is characteristic for some inorganic glasses and they are able to participate in biological processes of living organisms (plants, animals and human bodies). An example here is the selective removal of silicate-phosphate glass components under the influence of biological solutions, which has been applied in designing glasses acting as ecological fertilizers of controlled release rate of the nutrients for plants. The structure of model silicate-phosphate glasses containing the different amounts of the glass network formers, i.e. Ca 2+ and Mg 2+, as a binding components were studied. These elements besides other are indispensable of the normal growth of plants. In order to establish the function and position occupied by the particular components in the glass structure, the glasses were examined by FTIR spectroscopy (with spectra decomposition) and XRD methods. It has been found that the increasing amount of MgO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes systematically from a structure of the cristobalite type to a structure corresponding to forsterite type. Whilst the increasing content of CaO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes from a structure typical for cristobalite through one similar to the structure of calcium orthophosphate, to a structure corresponding to calcium silicates. The changing character of domains structure is the reason of different chemical activity of glasses.

  9. Fluorescence spectroscopic studies of DNA dynamics

    SciTech Connect

    Scalettar, B.A.

    1987-04-01

    Random solvent induced motions of DNA are manifest as nanosecond torsional oscillations of the helix backbone, nanosecond through millisecond bending deformations and overall rotational and translational diffusion of the polymer. Fluorescence spectroscopy is used to study this spectrum of DNA motions while ethidium monoazide was covalently bounded. The steady state fluorescence depolarization data indicate that the covalent monoazide/DNA complex exhibits internal motions characterized by an average angular amplitude of 26 degrees confirming reports of fast torsional oscillations in noncovalent ethidium bromide/DNA systems. Data obtained by use of a new polarized photobleaching recovery technique (FPR) reflect both the rotational dynamics of the polymer and the reversible photochemistry of the dye. To isolate the reorientational motion of the DNA, the FPR experiments were ran in two modes that differ only in the polarization of the bleaching light. A quotient function constructed from the data obtained in these two modes monitors only the rotational component of the FPR recovery. In specific applications those bending deformations of long DNA molecules that have characteristic relaxation times on the order of 100 microseconds have been resolved. A fluorescence correlation technique that relates fluctuations in particle number to center-of-mass motion was used to measure translational diffusion on coefficients of the plasmid PBR322 and a short oligomeric DNA. A theory that describes angular correlation in systems exhibiting cyclic, biologically directed reorientation and random Brownian rotation is developed.

  10. Toward the characterization of biological toxins using field-based FT-IR spectroscopic instrumentation

    NASA Astrophysics Data System (ADS)

    Schiering, David W.; Walton, Robert B.; Brown, Christopher W.; Norman, Mark L.; Brewer, Joseph; Scott, James

    2004-12-01

    IR spectroscopy is a broadly applicable technique for the identification of covalent materials. Recent advances in instrumentation have made Fourier Transform infrared (FT-IR) spectroscopy available for field characterization of suspect materials. Presently, this instrumentation is broadly deployed and used for the identification of potential chemical hazards. This discussion concerns work towards expanding the analytical utility of field-based FT-IR spectrometry in the characterization of biological threats. Two classes of materials were studied: biologically produced chemical toxins which were non-peptide in nature and peptide toxin. The IR spectroscopic identification of aflatoxin-B1, trichothecene T2 mycotoxin, and strychnine was evaluated using the approach of spectral searching against large libraries of materials. For pure components, the IR method discriminated the above toxins at better than the 99% confidence level. The ability to identify non-peptide toxins in mixtures was also evaluated using a "spectral stripping" search approach. For the mixtures evaluated, this method was able to identify the mixture components from ca. 32K spectral library entries. Castor bean extract containing ricin was used as a representative peptide toxin. Due to similarity in protein spectra, a SIMCA pattern recognition methodology was evaluated for classifying peptide toxins. In addition to castor bean extract the method was validated using bovine serum albumin and myoglobin as simulants. The SIMCA approach was successful in correctly classifying these samples at the 95% confidence level.

  11. Spectroscopic studies of alkaline activated slag geopolymers

    NASA Astrophysics Data System (ADS)

    Mozgawa, W.; Deja, J.

    2009-04-01

    In the work, results of structural studies of different geopolymers, obtained using a granulated blast furnace slag, are presented. The slag was subjected to an alkaline activation process. As activators, NaOH, Na 2CO 3 and liquid glass were applied. IR and NMR spectroscopy were the main experimental methods used, the results obtained were compared with XRD phase analysis and SEM observations. In the IR spectra of raw slag as well as in the spectra of products of paste hydration, the bands due to the characteristic vibrations of bonds observed in both types of oxygen bridges: Si-O-Si and Si-O-Al, were assigned. These bridges constitute basic structural units, forming tetrahedral geopolymer chains. It was found that the slag composition, mainly SiO 2/Al 2O 3 ratio and modification in oxides concentration, influences the presence of the bands connected with the phases (mainly C-S-H) formed during the hydration in the IR spectra. Additionally, significant effect of amorphous phases share on the spectra shape was established. 29Si and 27Al MAS-NMR spectra of initial slag geopolymers and pastes provided information concerning coordination of both atoms in the structures. It was revealed that the kind of slag geopolymers and the conditions of paste hydration influence connectedness of silicooxygen tetrahedra and coordination number of aluminium atoms. Based on IR spectra, it was also possible to determine the influence of the activator type, activation time and hydration conditions on the products formed. Significant changes were observed for the bands assigned to vibrations of carbonate and hydroxide groups. The changes were also noticed in the case of bands due to vibrations of silicate and aluminosilicate bonds.

  12. THE APOKASC CATALOG: AN ASTEROSEISMIC AND SPECTROSCOPIC JOINT SURVEY OF TARGETS IN THE KEPLER FIELDS

    SciTech Connect

    Pinsonneault, Marc H.; Epstein, Courtney; Johnson, Jennifer A.; Elsworth, Yvonne; Chaplin, William J.; Hekker, Saskia; Silva Aguirre, Victor; Stello, Dennis; Mészáros, Sz.; García, Rafael A.; Beck, Paul; Mathur, Savita; García Pérez, Ana; Girardi, Léo; Basu, Sarbani; Shetrone, Matthew; Allende Prieto, Carlos; Beers, Timothy C.; and others

    2015-01-01

    We present the first APOKASC catalog of spectroscopic and asteroseismic properties of 1916 red giants observed in the Kepler fields. The spectroscopic parameters provided from the Apache Point Observatory Galactic Evolution Experiment project are complemented with asteroseismic surface gravities, masses, radii, and mean densities determined by members of the Kepler Asteroseismology Science Consortium. We assess both random and systematic sources of error and include a discussion of sample selection for giants in the Kepler fields. Total uncertainties in the main catalog properties are of the order of 80 K in T {sub eff}, 0.06 dex in [M/H], 0.014 dex in log g, and 12% and 5% in mass and radius, respectively; these reflect a combination of systematic and random errors. Asteroseismic surface gravities are substantially more precise and accurate than spectroscopic ones, and we find good agreement between their mean values and the calibrated spectroscopic surface gravities. There are, however, systematic underlying trends with T {sub eff} and log g. Our effective temperature scale is between 0 and 200 K cooler than that expected from the infrared flux method, depending on the adopted extinction map, which provides evidence for a lower value on average than that inferred for the Kepler Input Catalog (KIC). We find a reasonable correspondence between the photometric KIC and spectroscopic APOKASC metallicity scales, with increased dispersion in KIC metallicities as the absolute metal abundance decreases, and offsets in T {sub eff} and log g consistent with those derived in the literature. We present mean fitting relations between APOKASC and KIC observables and discuss future prospects, strengths, and limitations of the catalog data.

  13. Spectroscopic studies of cold, gas-phase biomolecular ions

    NASA Astrophysics Data System (ADS)

    Rizzo, Thomas R.; Stearns, Jaime A.; Boyarkin, Oleg V.

    While the marriage of mass spectrometry and laser spectroscopy is not new, developments over the last few years in this relationship have opened up new horizons for the spectroscopic study of biological molecules. The combination of electrospray ionisation for producing large biological molecules in the gas phase together with cooled ion traps and multiple-resonance laser schemes are allowing spectroscopic investigation of individual conformations of peptides with more than a dozen amino acids. Highly resolved infrared spectra of single conformations of such species provide important benchmarks for testing the accuracy of theoretical calculations. This review presents a number of techniques employed in our laboratory and in others for measuring the spectroscopy of cold, gas-phase protonated peptides. We show examples that demonstrate the power of these techniques and evaluate their extension to still larger biological molecules.

  14. Study of Characterization of Pure and Malachite Green Doped Samples Using Spectroscopic Studies

    NASA Astrophysics Data System (ADS)

    Mishra, Jyoti; Mishra, Pankaj K.; Khare, P. K.

    2011-07-01

    This paper describes the results of SEM, EDX, UV-vis and TSDC study of malachite green doped PVK thermelectrets. TSDC study has been carried out in the temperature range 300 °C to 1500 °C with four different polarizing fields. One peak was observed at 110±10 °C which shifts toward high temperature with the increase in polarizing field. The activation energy found by initial rise method are 0.27±0.02 eV for pure and 0.40±0.03 eV for malachite green doped PVK thermoelectrets. Spectroscopic study concluded that impregnation of malachite green in polymer matrix forms charge transfer complexes.

  15. The magnetic field of the double-lined spectroscopic binary system HD 5550

    NASA Astrophysics Data System (ADS)

    Alecian, E.; Tkachenko, A.; Neiner, C.; Folsom, C. P.; Leroy, B.

    2016-05-01

    Context. The origin of fossil fields in intermediate- and high-mass stars is poorly understood, as is the interplay between binarity and magnetism during stellar evolution. Thus we have begun a study of the magnetic properties of a sample of intermediate-mass and massive short-period binary systems as a function of binarity properties. Aims: This paper specifically aims to characterise the magnetic field of HD 5550, a double-lined spectroscopic binary system of intermediate mass. Methods: We gathered 25 high-resolution spectropolarimetric observations of HD 5550 using the instrument Narval. We first fitted the intensity spectra using Zeeman/ATLAS9 LTE synthetic spectra to estimate the effective temperatures, microturbulent velocities, and the abundances of some elements of both components, as well as the light ratio of the system. We then applied the multi-line least-square deconvolution (LSD) technique to the intensity and circularly polarised spectra, which provided us with mean LSD I and V line profiles. We fitted the Stokes I line profiles to determine the radial and projected rotational velocities of both stars. We then analysed the shape and evolution of the V profiles using the oblique rotator model to characterise the magnetic fields of both stars. Results: We confirm the Ap nature of the primary, which has previously been reported, and find that the secondary displays spectral characteristics typical of an Am star. While a magnetic field is clearly detected in the lines of the primary, no magnetic field is detected in the secondary in any of our observations. If a dipolar field were present at the surface of the Am star, its polar strength must be below 40 G. The faint variability observed in the Stokes V profiles of the Ap star allowed us to propose a rotation period of 6.84-0.39+0.61 d, which is close to the orbital period (~6.82 d), suggesting that the star is synchronised with its orbit. By fitting the variability of the V profiles, we propose that the

  16. Conceptual design study to determine optimal enclosure vent configuration for the Maunakea Spectroscopic Explorer (MSE)

    NASA Astrophysics Data System (ADS)

    Szeto, Kei; Vogiatzis, Konstantinos; Hangan, Horia; Jubayer, Chowdhury M.; Breckenridge, Craig; Loewen, Nathan; Bauman, Steven; Salmon, Derrick

    2014-07-01

    The Maunakea Spectroscopic Explorer (MSE; formerly Next Generation Canada-France-Hawaii Telescope) is a dedicated, 10m aperture, wide-field, fiber-fed multi-object spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The enclosure vent configuration design study is the last of three studies to examine the technical feasibility of the proposed MSE baseline concept. The enclosure vent configuration study compares the aero-thermal performance of three enclosure ventilation configurations based on the predicted dome thermal seeing and air flow attenuation over the enclosure aperture opening of a Calotte design derived from computational fluid dynamics simulations. In addition, functional and operation considerations such as access and servicing of the three ventilation configurations is discussed.

  17. Palm-size wide-field Fourier spectroscopic imager with uncooled infrared microbolometer arrays for smartphone

    NASA Astrophysics Data System (ADS)

    Kawashima, Natsumi; Suzuki, Yo; Qi, Wei; Hosono, Satsuki; Saito, Tsubasa; Ogawa, Satoshi; Sato, Shun; Fujiwara, Masaru; Nishiyama, Akira; Wada, Kenji; Tanaka, Naotaka; Ishimaru, Ichiro

    2015-03-01

    We proposed the imaging-type 2-dimensional Fourier spectroscopy that is a near-common-path interferometer with strong robustness against mechanical vibrations. We introduced the miniature uncooled infrared microbolometer arrays for smartphone (e.g. product name: FILR ONE price: around 400USD). And we constructed the phase-shifter with the piezo impact drive mechanism (maker: Technohands.co.Ltd., stroke: 4.5mm, resolution: 0.01μm, size: 20mm, price: around 800USD). Thus, we realized the palm-size mid-infrared spectroscopic imager [size: L56mm×W69mm×H43mm weight: 500g]. And by using wide-angle lens as objective lens, the proposed method can obtain the wide-field 2- dimensional middle-infrared (wavelength: 7.5-13.5[μm]) spectroscopic imaging of radiation lights emitted from human bodies itself

  18. Spectroscopic and dynamical studies of highly energized small polyatomic molecules

    SciTech Connect

    Field, R.W.; Silbey, R.J.

    1993-12-01

    The authors have initiated a program to perform spectroscopic and dynamic studies of small molecules. Large amplitude motions in excited acetylene were discussed along with plans to record the dispersed fluorescence (DF) and the stimulated emission pumping (SEP) spectra. SEP spectra were reported for the formyl radical. A Fourier transform spectrometer was discussed with respect to its ability to probe the structure of radicals. This instrument is capable of performing studies using various techniques such as magnetic rotation spectroscopy and sub-Doppler sideband-OODR Zeman (SOODRZ) spectroscopy.

  19. Using Spectroscopic Profiles to Study the Morphology of Comets

    NASA Astrophysics Data System (ADS)

    Harris, Ien; Pierce, Donna M.; Cochran, Anita L.

    2016-10-01

    We have used the integral-field unit spectrograph (the George and Cynthia Mitchell Spectrograph) on the 2.7m Harlan J. Smith telescope at McDonald Observatory to obtain spectroscopic images of the comae of several comets. The images were obtained for various radical species (C2, C3. CH, CN, NH2). Radial and azimuthal average profiles of the radical species were created to enhance any observed cometary coma morphological features. We compare the observed coma features across the observed species and over the different observation periods in order to constrain possible rotational states of the observed comets. We will present results for several comets, including 2009P1 (Garradd). This work was funded by NASA's Planetary Atmospheres program (Award No. NNX14AH186).

  20. Models of chemical biosignatures - a vibrational spectroscopic study

    NASA Astrophysics Data System (ADS)

    Bödeker, B.; Böttger, U.; Hübers, H.-W.; deVera, J.-P.; Fox, S.; Strasdeit, H.

    2013-09-01

    Investigating possible biosignatures is of central interest in the search for the oldest traces of terrestrial life. Possible biosignatures are: (i) physical structures, such as fossilized single-celled or colonyforming microorganisms; (ii) biomolecules and their altered residues (chemical biosignatures); (iii) altered element, isotope and mineral compositions in former microbial habitats and related effects caused by metabolic activity [1]. New insights in this field of research are also important in the search for life on other planets and moons, especially Mars. However, abiotically formed organic compounds are widely distributed in the universe. Therefore, in future Mars missions, it will be essential to know whether organic molecules are actually of biological origin. Here, we describe the syntheses and spectroscopic (Raman and infrared) properties of artificial chemical biosignatures that might help answering this question.

  1. Raman spectroscopic study of a genetically altered kidney cell

    NASA Astrophysics Data System (ADS)

    Joshi, Joel; Garcia, Francisco; Centeno, Silvia P.; Joshi, N. V.

    2008-02-01

    A Raman spectroscopic investigation of a genetically altered Human Embryonic Kidney Cell (HEK293) along with a pathologically normal cell has been carried out by a conventional method. The genetic alteration was carried out with a standard protocol by using a Green Fluorescence Protein (GFP). Raman spectra show that there are dramatic differences between the spectrum obtained from a genetically altered cell and that obtained from a pathologically normal cell. The former shows three broad bands; meanwhile the latter shows several sharp peaks corresponding to the ring vibrational modes of Phen, GFP and DNA. The present analysis provides an indication that the force field near Phen located at 64, 65 and 66 was altered during the genetic transformation. The Raman spectrum could be a direct experimental evidence for substantial modifications triggered due to the expression of specific genes.

  2. 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.

  3. Vibrational spectroscopic studies of newly developed synthetic biopolymers.

    PubMed

    Bista, Rajan K; Bruch, Reinhard F; Covington, Aaron M

    2010-05-01

    Vibrational spectroscopic techniques such as near-infrared (NIR), Fourier transform infrared (FTIR), and Raman spectroscopy are valuable diagnostic tools that can be used to elucidate comprehensive structural information of numerous biological samples. In this review article, we have highlighted the advantages of nanotechnology and biophotonics in conjunction with vibrational spectroscopic techniques in order to understand the various aspects of new kind of synthetic biopolymers termed as polyethylene glycol (PEG)ylated lipids. In contrast to conventional phospholipids, these novel lipids spontaneously form liposomes or nanovesicles upon hydration, without the supply of external activation energy. The amphiphiles considered in this study differ in their hydrophobic acyl chain length and contain different units of PEG hydrophilic headgroups. We have further explored the thermotropic phase behaviors and associated changes in the conformational order/disorder of such lipids by using variable-temperature FTIR and Raman spectroscopy. Phase transition temperature profiles and correlation between various spectral indicators have been identified by either monitoring the shifts in the vibrational peak positions or plotting vibrational peak intensity ratios in the C--H stretching region as a function of temperature. To supplement our observations of phase transformations, a thermodynamic approach known as differential scanning calorimetry (DSC) has been applied and revealed a good agreement with the infrared and Raman spectroscopic data. Finally, the investigation of thermal properties of lipids is extremely crucial for numerous purposes, thus the results obtained in this work may find application in a wide variety of studies including the development of PEGylated lipid based drug and substances delivery vehicles.

  4. Transport and spectroscopic studies of liquid and polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Bopege, Dharshani Nimali

    Liquid and polymer electrolytes are interesting and important materials to study as they are used in Li rechargeable batteries and other electrochemical devices. It is essential to investigate the fundamental properties of electrolytes such as ionic conductivity, diffusion, and ionic association to enhance battery performance in different battery markets. This dissertation mainly focuses on the temperature-dependent charge and mass transport processes and ionic association of different electrolyte systems. Impedance spectroscopy and pulsed field gradient nuclear magnetic resonance spectroscopy were used to measure the ionic conductivity and diffusion coefficients of ketone and acetate based liquid electrolytes. In this study, charge and mass transport in non-aqueous liquid electrolytes have been viewed from an entirely different perspective by introducing the compensated Arrhenius formalism. Here, the conductivity and diffusion coefficient are written as an Arrhenius-like expression with a temperature-dependent static dielectric constant dependence in the exponential prefactor. The compensated Arrhenius formalism reported in this dissertation very accurately describes temperature-dependent conductivity data for acetate and ketone-based electrolytes as well as temperature-dependent diffusion data of pure solvents. We found that calculated average activation energies of ketone-based electrolytes are close to each other for both conductivity and diffusion data (in the range 24-26 kJ/mol). Also, this study shows that average activation energies of acetate-based electrolytes are higher than those for the ketone systems (in the range 33-37 kJ/mol). Further, we observed higher dielectric constants and ionic conductivities for both dilute and concentrated ketone solutions with temperature. Vibrational spectroscopy (Infrared and Raman) was used to probe intermolecular interactions in both polymer and liquid electrolytes, particularly those which contain lithium

  5. 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.

  6. Spectroscopic studies of carbon impurities in PISCES-A

    SciTech Connect

    Ra, Y.; Hirooka, Y.; Leung, W.K.; Conn, R.W. . Inst. of Plasma and Fusion Research); Pospieszczyk, A. . Inst. fuer Plasmaphysik)

    1989-08-01

    The graphite used for the limiter of the tokamak reactor produces carbon-containing molecular impurities as a result of the interactions with the edge plasma. The behavior of these molecular impurities has been studied using emission spectroscopy. The present study includes: finding molecular bands and atomic lines in the visible spectral range which can be used for the study of the molecular impurities, studying the breakup processes of the molecular impurities on their way from the source into the plasma, developing a spectroscopic diagnostic method for the absolute measurement of the molecular impurity flux resulting from graphite erosion. For these studies, carbon-containing molecules such as CH{sub 4}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and CO{sub 2} were injected into the tokamak-boundary,like plasma generated by PISCES-A. The spectrograms of these gases were taken. Many useful bands and lines were determined from the spectrograms. The breakup processes of these gases were studied by observing the spatial profiles of the emission of the molecules and their radicals for different plasma conditions. For the absolute measurement of the eroded molecular impurity flux, the photon efficiency of the lines and bands were found by measuring the absolute number of the emitted photons and injected gas molecules. The chemical sputtering yield of graphite by hydrogen plasma was spectroscopically measured using the previously obtained photon efficiencies. It showed good agreement with results obtained by weight loss measurements. 16 refs., 7 figs., 1 tab.

  7. Protonated Nitrous Oxide, NNOH(+): Fundamental Vibrational Frequencies and Spectroscopic Constants from Quartic Force Fields

    NASA Technical Reports Server (NTRS)

    Huang, Xinchuan; Fortenberry, Ryan C.; Lee, Timothy J.

    2013-01-01

    The interstellar presence of protonated nitrous oxide has been suspected for some time. Using established high-accuracy quantum chemical techniques, spectroscopic constants and fundamental vibrational frequencies are provided for the lower energy O-protonated isomer of this cation and its deuterated isotopologue. The vibrationally-averaged B0 and C0 rotational constants are within 6 MHz of their experimental values and the D(subJ) quartic distortion constants agree with experiment to within 3%. The known gas phase O-H stretch of NNOH(+) is 3330.91 cm(exp-1), and the vibrational configuration interaction computed result is 3330.9 cm(exp-1). Other spectroscopic constants are also provided, as are the rest of the fundamental vibrational frequencies for NNOH(+) and its deuterated isotopologue. This high-accuracy data should serve to better inform future observational or experimental studies of the rovibrational bands of protonated nitrous oxide in the ISM and the laboratory.

  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. [Spectroscopic studies on transition metal ions in colored diamonds].

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

    Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples.

  10. Time Domain Reflectometric and spectroscopic studies on toluene + butyronitrile solution

    NASA Astrophysics Data System (ADS)

    Karthick, N. K.; Arivazhagan, G.; Kumbharkhane, A. C.; Joshi, Y. S.; Kannan, P. P.

    2016-03-01

    The dielectric parameters of toluene + butyronitrile solution have been obtained by time domain reflectometry (TDR) technique in the frequency range from 10 MHz to 30 GHz at 298 K. Spectroscopic (FTIR and 13C NMR) studies have also been carried out on the solution and the results of the studies show that neat butyronitrile is self-associative through C-H⋯N contacts and weak intermolecular forces of C-H⋯N and C-H⋯π type are operative in the solution. The obtained dielectric parameters such as Kirkwood correlation factor g, relaxation time τ etc. have been analyzed in view of these weak intermolecular forces. The weak non-covalent interactions between heteromolecules appear to have no influence on the ideality of ɛm vs X2 curve of the solution. Heteromolecular entities with weak intermolecular forces experience larger hindrance leading to longer relaxation time τ.

  11. Crystallographic and spectroscopic study on a known orally active progestin.

    PubMed

    Ferraboschi, Patrizia; Ciuffreda, Pierangela; Ciceri, Samuele; Grisenti, Paride; Castellano, Carlo; Meneghetti, Fiorella

    2015-12-01

    6,17α-Dimethyl-4,6-pregnadiene-3,20-dione (medrogestone, 2) is for a long time known steroid endowed with progestational activity. In order to study its crystallographic and NMR spectroscopic properties with the aim to fill the literature gap, we prepared medrogestone following a traditional procedure. A careful NMR study allowed the complete assignment of the (1)H and (13)C NMR signals not only of medrogestone but also of its synthetic intermediates. The structural and stereochemical characterizations of medrogestone together with its precursor 17α-methyl-3-ethoxy-pregna-3,5-dien-20-one were described by means of X-ray analysis, allowing a deepened conformational investigation.

  12. Laser-spectroscopic electric field measurements in a ns-pulsed microplasma in nitrogen

    NASA Astrophysics Data System (ADS)

    Boehm, Patrick; Luggenhoelscher, Dirk; Czarnetzki, Uwe; 1123 Research Group Collaboration

    2013-09-01

    In this work for the first time ns-pulsed discharges in nitrogen at near atmospheric pressures are investigated by laser-spectroscopic electric field measurements, ultra-fast optical emission spectroscopy, current and voltage measurements. The discharge is operated with kV-pulses of about 150 ns duration between two parallel plate electrodes with a 1.2 mm gap. The laser technique for electric field measurement is based on a four-wave mixing process similar to Coherent anti-Stokes Raman Scattering (CARS). Here the static electric field acts effectively as the third wave with a zero frequency. The frequency of the generated anti-Stokes wave is in the IR regime and the amplitude is proportional to the electric field strength. By measuring the intensity of the IR- and anti-Stokes-signal it is now possible to determine the static electric field. Due to the short pulse-length of the lasers a temporal resolution in the ns range and a typical sensitivity of 50 - 100 V/mm in pure nitrogen is achieved (p > 50 mbar). Field-measurements are accompanied by emission measurements using a streak-camera with sub-ns resolutions. Further, current and voltage measurements combined with the electric field measurements allow determination of the plasma density. Funding by DFG through FOR 1123.

  13. 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.

  14. Spectroscopic studies of anthracyclines: Structural characterization and in vitro tracking

    NASA Astrophysics Data System (ADS)

    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 488 nm and 785 nm 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.

  15. Spectroscopic study of Gd nanostructures quantum confined in Fe corrals

    PubMed Central

    Cao, R. X.; Sun, L.; Miao, B. F.; Li, Q. L.; Zheng, C.; Wu, D.; You, B.; Zhang, W.; Han, P.; Bader, S. D.; Zhang, W. Y.; Ding, H. F.

    2015-01-01

    Low dimensional nanostructures have attracted attention due to their rich physical properties and potential applications. The essential factor for their functionality is their electronic properties, which can be modified by quantum confinement. Here the electronic states of Gd atom trapped in open Fe corrals on Ag(111) were studied via scanning tunneling spectroscopy. A single spectroscopic peak above the Fermi level is observed after Gd adatoms are trapped inside Fe corrals, while two peaks appear in empty corrals. The single peak position is close to the higher energy peak of the empty corrals. These findings, attributed to quantum confinement of the corrals and Gd structures trapped inside, are supported by tight-binding calculations. This demonstrates and provides insights into atom trapping in open corrals of various diameters, giving an alternative approach to modify the properties of nano-objects. PMID:26160318

  16. Spectroscopic study of Gd nanostructures quantum confined in Fe corrals

    SciTech Connect

    Cao, R. X.; Sun, L.; Miao, B. F.; Li, Q. L.; Zheng, C.; Wu, D.; You, B.; Zhang, W.; Han, P.; Bader, S. D.; Zhang, W. Y.; Ding, H. F.

    2015-07-10

    Low dimensional nanostructures have attracted attention due to their rich physical properties and potential applications. The essential factor for their functionality is their electronic properties, which can be modified by quantum confinement. Here the electronic states of Gd atom trapped in open Fe corrals on Ag(111) were studied via scanning tunneling spectroscopy. A single spectroscopic peak above the Fermi level is observed after Gd adatoms are trapped inside Fe corrals, while two peaks appear in empty corrals. The single peak position is close to the higher energy peak of the empty corrals. These findings, attributed to quantum confinement of the corrals and Gd structures trapped inside, are supported by tight-binding calculations. As a result, this demonstrates and provides insights into atom trapping in open corrals of various diameters, giving an alternative approach to modify the properties of nano-objects.

  17. Molecular spectroscopic study for suggested mechanism of chrome tanned leather

    NASA Astrophysics Data System (ADS)

    Nashy, Elshahat H. A.; Osman, Osama; Mahmoud, Abdel Aziz; Ibrahim, Medhat

    2012-03-01

    Collagen represents the structural protein of the extracellular matrix, which gives strength of hides and/or skin under tanning process. Chrome tan is the most important tanning agent all over the world. The methods for production of leather evolved over several centuries as art and engineering with little understanding of the underlying science. The present work is devoted to suggest the most probable mechanistic action of chrome tan on hide proteins. First the affect of Cr upon hide protein is indicated by the studied mechanical properties. Then the spectroscopic characterization of the hide protein as well as chrome tanned leather was carried out with Horizontal Attenuated Total Reflection (HATR) FT-IR. The obtained results indicate how the chromium can attached with the active sites of collagen. Molecular modeling confirms that chromium can react with amino as well as carboxylate groups. Four schemes were obtained to describe the possible interactions of chrome tan with hide proteins.

  18. A detailed spectroscopic study of an Italian fresco

    SciTech Connect

    Barilaro, Donatella; Crupi, Vincenza; Majolino, Domenico; Barone, Germana; Ponterio, Rosina

    2005-02-15

    In the present work we characterized samples of plasters and pictorial layers taken from a fresco in the Acireale Cathedral. The fresco represents the Coronation of Saint Venera, patron saint of this Ionian town. By performing a detailed spectroscopic analysis of the plaster preparation layer by Fourier-transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD), and of the painting layer by FTIR and confocal Raman microspectroscopy, scanning electron microscopy+energy dispersive x-ray spectroscopy, and XRD, we were able to identify the pigments and the binders present. In particular, Raman investigation was crucial to the characterization of the pigments thanks to the high resolution of the confocal apparatus used. It is worth stressing that the simultaneous use of complementary techniques was able to provide more complete information for the conservation of the artifact we studied.

  19. Spectroscopic study of Gd nanostructures quantum confined in Fe corrals

    DOE PAGES

    Cao, R. X.; Sun, L.; Miao, B. F.; ...

    2015-07-10

    Low dimensional nanostructures have attracted attention due to their rich physical properties and potential applications. The essential factor for their functionality is their electronic properties, which can be modified by quantum confinement. Here the electronic states of Gd atom trapped in open Fe corrals on Ag(111) were studied via scanning tunneling spectroscopy. A single spectroscopic peak above the Fermi level is observed after Gd adatoms are trapped inside Fe corrals, while two peaks appear in empty corrals. The single peak position is close to the higher energy peak of the empty corrals. These findings, attributed to quantum confinement of themore » corrals and Gd structures trapped inside, are supported by tight-binding calculations. As a result, this demonstrates and provides insights into atom trapping in open corrals of various diameters, giving an alternative approach to modify the properties of nano-objects.« less

  20. 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.

  1. Spectroscopic Study of Low Mass Members of NGC 2244

    NASA Astrophysics Data System (ADS)

    Alty, Michelle; Ybarra, Jason E.; Román-Zúñiga, Carlos G.; Lada, Elizabeth A.

    2017-01-01

    The results of a near-infrared spectroscopic study of low-mass stars in open cluster NGC 2244 are presented. JH spectra of the stars were obtained using the FLAMINGOS instrument at KPNO. To determine cluster membership, we used Spitzer Space Telescope mid-infrared photometry along with X-ray detections from the Chandra X-ray Observatory. The stars were spectral typed using absorption line ratios and spectral shapes. The stars were then plotted on an H-R diagram along with theoretical isochrones. We discuss these results in context of cluster evolution in the Rosette Molecular Complex. Work supported, in part, by the Dr. John W. Martin Summer Science Research Institute at Bridgewater College.

  2. 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.

  3. Spectroscopic Capabilities of XMM for Stellar Coronal Studies

    NASA Astrophysics Data System (ADS)

    Pallavicini, R.

    The turn of the millennium will be a marvelous time for X-ray astronomy with the launch of powerful missions such as AXAF, XMM, and ASTRO-E. Stellar coronae, with their spectra rich in emission lines, will be primary targets to exploit the spectroscopic capabilities of these missions. In particular, the CCD cameras and reflection gratings on XMM will allow us to address a number of key questions in stellar coronal physics. The capabilities of XMM for the study of stellar coronae are illustrated by means of simulations of EPIC and RGS spectra for a variety of typical stellar coronal sources. The mission time-line and the policy for accessing the data are also briefly illustrated.

  4. Laser irradiated gas jet: A spectroscopic experimental and theoretical study

    SciTech Connect

    Lee, R.W.; Matthews, D.L.; Koppel, L.; Busch, G.E.; Charatis, G.; Dunning, M.J.; Mayer, F.J.

    1983-09-01

    We present x-ray spectroscopic measurements of the longitudinal electron density profile and the longitudinal and transverse electron temperature profiles for a laser irradiated gas jet. We attempt to verify our spectroscopic method by laser interferometry and by comparison of inferred quantities to those determined from laser plasma interaction simulations. Because temperature profiles were time dependent, we used a theoretical time dependent radiation transport code to analyze the data.

  5. Feasibility Demonstration of Wide-Field Fourier-Spectroscopic-Imaging in Infrared Region

    NASA Astrophysics Data System (ADS)

    Qi, Wei; Takuma, Takashi; Tsutsumi, Ryosuke; Inui, Asuka; Kagiyama, Hiroyasu; Kojima, Daisuke; Nishiyama, Akira; Ishimaru, Ichirou

    We are aiming at the realization of living-environment sensor and non-invasive blood-sugar sensor by the proposed imaging type 2-D Fourier spectroscopy. This method is based on the phase-shift interference between the object beams. As a result, even if the object beams are spatially incoherent, we can observe the phase-shift interference phenomena. In the near infrared region, we can obtain the high-contrast blood vessel image of mouse's ear in the deeper part by InGaAs camera. Furthermore, in the mid-infrared region, we have successfully measured the radiation spectroscopic-imaging with wild field of view by the infrared module, such as the house plants.

  6. Spatially resolved optical and ultrastructural properties of colorectal and pancreatic field carcinogenesis observed by inverse spectroscopic optical coherence tomography

    PubMed Central

    Yi, Ji; Radosevich, Andrew J.; Stypula-Cyrus, Yolanda; Mutyal, Nikhil N.; Azarin, Samira Michelle; Horcher, Elizabeth; Goldberg, Michael J.; Bianchi, Laura K.; Bajaj, Shailesh; Roy, Hemant K.; Backman, Vadim

    2014-01-01

    Abstract. Field carcinogenesis is the initial stage of cancer progression. Understanding field carcinogenesis is valuable for both cancer biology and clinical medicine. Here, we used inverse spectroscopic optical coherence tomography to study colorectal cancer (CRC) and pancreatic cancer (PC) field carcinogenesis. Depth-resolved optical and ultrastructural properties of the mucosa were quantified from histologically normal rectal biopsies from patients with and without colon adenomas (n=85) as well as from histologically normal peri-ampullary duodenal biopsies from patients with and without PC (n=22). Changes in the epithelium and stroma in CRC field carcinogenesis were separately quantified. In both compartments, optical and ultra-structural alterations were consistent. Optical alterations included lower backscattering (μb) and reduced scattering (μs′) coefficients and higher anisotropy factor g. Ultrastructurally pronounced alterations were observed at length scales up to ∼450  nm, with the shape of the mass density correlation function having a higher shape factor D, thus implying a shift to larger length scales. Similar alterations were found in the PC field carcinogenesis despite the difference in genetic pathways and etiologies. We further verified that the chromatin clumping in epithelial cells and collagen cross-linking caused D to increase in vitro and could be among the mechanisms responsible for the observed changes in epithelium and stroma, respectively. PMID:24643530

  7. Field-widened Michelson interferometer system as the spectroscopic filter of high-spectral-resolution lidar

    NASA Astrophysics Data System (ADS)

    Cheng, Zhongtao; Liu, Dong; Zhou, Yudi; Yang, Yongying; Zhang, Yupeng; Luo, Jing; Bai, Jian; Liu, Chong; Shen, Yibing

    2016-05-01

    We propose and develop a field-widened Michelson interferometer (FWMI) system to act as a new type of spectroscopic filter in HSRL application. Due to the field widening characteristic, the FWMI can allow relatively large off-axis incident angle, and can be designed to any desirable wavelength. The theoretical foundations of the FWMI are introduced in this paper, and the developed prototype interferometer is described. It consists of a solid arm made of the glass H-ZF52 with the dimension of 37.876 mm, and an air gap with the length of 20.382 mm. These two interference arms are connected to a cube beam splitter to constitute a Michelson interferometer. Due to the matched dimensions and refractive indices of the two arms, the experimental testing results show that the OPD variation of the developed FWMI is about 0.04 lambda and the RMS is less than 0.008 lambda when the incident angle is as much as 1.5 degree (half angle). The cumulative wavefront distortion caused by the FWMI is less than 0.1 lambda PV value and 0.02 lambda RMS value. To lock the filtering frequency of the FWMI to the laser transmitter, a frequency locking system, which is actually an electro-optic feedback loop, is established. The setup and principle of this frequency locking system are also described in detail. Good locking accuracy of the FWMI about 27MHz is demonstrated through the frequency locking technique. All these results validate the feasibility of this developed FWMI system as a spectroscopic filter of an HSRL.

  8. EPR Spectroscopic Studies of [FeFe]-Hydrogenase Maturation.

    PubMed

    Suess, Daniel L M; Britt, R David

    2015-09-01

    Proton reduction and H2 oxidation are key elementary reactions for solar fuel production. Hydrogenases interconvert H(+) and H2 with remarkable efficiency and have therefore received much attention in this context. For [FeFe]-hydrogenases, catalysis occurs at a unique cofactor called the H-cluster. In this article, we discuss ways in which EPR spectroscopy has elucidated aspects of the bioassembly of the H-cluster, with a focus on four case studies: EPR spectroscopic identification of a radical en route to the CO and CN(-) ligands of the H-cluster, tracing (57)Fe from the maturase HydG into the H-cluster, characterization of the auxiliary Fe-S cluster in HydG, and isotopic labeling of the CN(-) ligands of HydA for electronic structure studies of its Hox state. Advances in cell-free maturation protocols have enabled several of these mechanistic studies, and understanding H-cluster maturation may in turn provide insights leading to improvements in hydrogenase production for biotechnological applications.

  9. Particle in a Disk: A Spectroscopic and Computational Laboratory Exercise Studying the Polycyclic Aromatic Hydrocarbon Corannulene

    ERIC Educational Resources Information Center

    Frey, E. Ramsey; Sygula, Andrzej; Hammer, Nathan I.

    2014-01-01

    This laboratory exercise introduces undergraduate chemistry majors to the spectroscopic and theoretical study of the polycyclic aromatic hydrocarbon (PAH), corannulene. Students explore the spectroscopic properties of corannulene using UV-vis and Raman vibrational spectroscopies. They compare their experimental results to simulated vibrational…

  10. Infrared Imaging, Spectroscopic, and Photometric Studies of Comets

    NASA Technical Reports Server (NTRS)

    Gehrz, Robert D.

    1997-01-01

    We have continued our program of infrared (IR) photometric, imaging, spectroscopic, and polarimetric temporal observations of comets to study the properties of comet dust and comet nuclei. During the first two years we digitized our IR data base on P/Halley and other recent comets to facilitate further analysis and comparison with other data bases, and found compelling evidence for the emission of a burst of small grains from P/Halley's nucleus at perihelion. We reported imaging and photometric observations of Comets Austin 1990 V and Swift-Tuttle 1992. The Swift-Tuttle 1992t observations included IR photometry, several 7-14 micron long-slit spectra of the coma and a time-sequence of more than 150 10 micron broadband images of the coma. An analysis of near-IR images of the inner coma of P/Halley obtained on three consecutive nights in 1986 March showed sunwardjets. We completed our analysis of IR imaging spectrosco-photometric data on comets. We also obtained observations of Comets Hyakutake 1996 B2 and Hale/Bopp 1995 01. We obtained infrared imaging, photometric, spectroscopic and polarimetric temporal observations of bright comets using a network of five telescopes, with emphasis on simultaneous observations of comets at many wavelengths with different instruments. Our program offers several unique advantages: 1) rapid observational response to new comets with dedicated infrared telescopes; 2) observations within a few degrees of the sun when comets are near perihelion and 3) access to advanced infrared array imagers and spectrometers. In particular, reduction, analysis, publication and archiving of our Jupiter/sl-9 and Comet Hyakutake infrared data received special emphasis. Instrumentation development included installation of the latest version of the innovative FORTH telescope control and a data acquisition system that enables us to control three telescopes remotely by telephone from anywhere in the world for comet observations in broad daylight. We have

  11. A spectroscopic study of the globular Cluster NGC 4147

    NASA Astrophysics Data System (ADS)

    Villanova, S.; Monaco, L.; Moni Bidin, C.; Assmann, P.

    2016-08-01

    We present the abundance analysis for a sample of 18 red giant branch stars in the metal-poor globular cluster NGC 4147 based on medium- and high-resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Y, Ba, and Eu. We find a metallicity of [Fe/H] = -1.84 ± 0.02 and an α-enhancement of +0.38 ± 0.05 (errors on the mean), typical of halo globular clusters in this metallicity regime. A significant spread is observed in the abundances of light elements C, N, O, Na, and Al. In particular, we found an Na-O anticorrelation and Na-Al correlation. The cluster contains only ˜15 per cent of stars that belong to the first generation (Na-poor and O-rich). This implies that it suffered a severe mass-loss during its lifetime. Its [Ca/Fe] and [Ti/Fe] mean values agree better with the Galactic halo trend than with the trend of extragalactic environments at the cluster metallicity. This possibly suggests that NGC 4147 is a genuine Galactic object at odd with what claimed by some author that proposed the cluster to be member of the Sagittarius dwarf galaxy. An antirelation between the light s-process element Y and Na may also be present.

  12. In vitro spectroscopic study of piperine-encapsulated nanosize liposomes.

    PubMed

    Pentak, Danuta

    2016-03-01

    Black pepper is a source of effective antioxidants. It contains several powerful antioxidants and is thus one of the most important spices for preventing and curtailing oxidative stress. There is considerable interest in the development of a drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic and amphiphilic molecules. This article focuses on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress. Liposome formulations of piperine were analyzed with various spectroscopic methods. The formulation with the highest entrapment efficiency (90.5%) was formulated with an L-α-phosphatidylcholine dipalmitoyl (DPPC):piperine, 30:1 molar ratio, and total lipid count of 19.47 mg/ml in the final liposomal preparation. The liposome formulation was found to be stable after storage at 4 °C, protected from light, for a minimum of 3 weeks. The incremental process of piperine penetration through the phospholipid membrane was analyzed using the FT-IR, UV-Vis and NMR methods. Temperature stability studies carried out at 37 °C showed the highest percentage of piperine release in the first 3 h of incubation.

  13. Spectroscopic Study on the Interaction of 4-dimethylaminochalcones with Phospholipids

    NASA Astrophysics Data System (ADS)

    Tomečková, V.; Revická, M.; Sassen, A.; Veliká, B.; Stupák, M.; Perjési, P.

    2014-11-01

    The ultraviolet-visible and fluorescence spectroscopic properties of 4'-dimethylaminochalcone ( 1a) and its cyclic analogs 2a-4a have been studied in the presence of phospholipid vesicles (i.e., egg yolk lecithin and dipalmitoylpho sphatidylcholine), bovine serum albumin (BSA), and lipoprotein particles (i.e., bovine serum albumin plus egg yolk lecithin). The spectral results showed that compounds 1a-4a formed hydrophobic interactions with the phospholipids, lipoproteins, and BSA at the polar/nonpolar interface. Compounds 3a and 4a exhibited the strongest hydrophobic interactions of all of the compounds tested towards the phospholipids. Compound 2a gave the best fluorescent fluorophore indicating interactions with the lipids, lipoproteins, and proteins. Fluorescent microscopic imaging of breast cancer cells treated with compounds 1a-4a revealed that they could be used to stain all of the cellular components and destroy the nuclear structure. Compounds 1a-4a were found to be concentrated predominantly on the surfaces of the liposomes and lipoproteins.

  14. Vibrational spectroscopic study of vinyl substituted polycyclic aromatic hydrocarbons.

    PubMed

    Maurya, Anju; Rastogi, Shantanu

    2015-12-05

    The mid infrared emission features observed in various astrophysical sources are attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The models of emission spectra from a collection of PAHs show uncertainty in matching the 6.2 μm feature. This indicates the need to consider a larger variety of PAHs and PAH derivatives. Chemical pathways towards formation of PAHs in the astrophysical environments involve vinyl substituted PAHs as intermediate products. Vibrational spectroscopic study of vinyl-PAHs is reported in the present work. The vinyl group is substituted at similar positions in eight different PAHs. The obtained optimized structures show that vinyl substitution at 2 position in acenes gives planar geometry, while all other vinyl-PAHs are non-planar. Infrared spectra is simulated for neutrals as well as for cations. The results are compared with the spectra of corresponding plain PAHs and analyzed for possible match with astrophysical observations. New features, due to vinyl group in the composite spectra, identified at 6.64, 6.92, 7.27, 8.77 and 10.35 μm fall close to some sub features of the observed emission spectra. The paper provides data that may be used in the emission models particularly along proto planetary nebulae type cool objects.

  15. Spectroscopic and Microscopic Study of Peroxyformic Pulping of Agave Waste.

    PubMed

    Hernández-Hernández, Hilda M; Chanona-Pérez, Jorge J; Vega, Alberto; Ligero, Pablo; Farrera-Rebollo, Reynold R; Mendoza-Pérez, Jorge A; Calderón-Domínguez, Georgina; Vera, Norma Güemes

    2016-10-01

    The peroxyformic process is based on the action of a carboxylic acid (mainly formic acid) and the corresponding peroxyacid. The influences of processing time (60-180 min), formic acid concentration (80-95%), temperature (60-80°C), and hydrogen peroxide concentration (2-4%) on peroxyformic pulping of agave leaves were studied by surface response methodology using a face-centered factorial design. Empirical models were obtained for the prediction of yield, κ number (KN) and pulp viscosity as functions of the aforementioned variables. Mathematical optimization enabled us to select a set of operational variables that produced the best fractionation of the material with the following results: pulp yield (26.9%), KN (3.6), and pulp viscosity (777 mL/g). Furthermore, this work allowed the description and evaluation of changes to the agave fibers during the fractionation process using different microscopic and spectroscopic techniques, and provided a comprehensive and qualitative view of the phenomena occurring in the delignification of agave fibers. The use of confocal and scanning electron microscopy provided a detailed understanding of the microstructural changes to the lignin and cellulose in the fibers throughout the process, whereas Raman spectroscopy and X-ray diffraction analysis indicated that cellulose in the pulp after treatment was mainly of type I.

  16. Spectroscopic study of HNO3 dissociation on ice.

    PubMed

    Marchand, Patrick; Marcotte, Guillaume; Ayotte, Patrick

    2012-12-13

    A detailed spectroscopic study of HNO(3):H(2)O binary amorphous mixtures, and of the adsorption of HNO(3) onto ice, is reported. Using a classical optics model, the extent of intermixing and of ionic dissociation of adsorbed HNO(3), which forms a strong acid with liquid water, is determined as a function of HNO(3) coverage and temperature. Even at temperatures as low as 45 K, where intermixing is limited to at most a few molecular layers at the interface, ionic dissociation of adsorbed HNO(3) is observed to be extensive. While some amount of molecularly adsorbed HNO(3) is observed at the surface of ice at 45 K, its ionic dissociation occurs irreversibly upon heating the ice substrate to 120 K. The molecularly adsorbed state of HNO(3) is not restored upon cooling, suggesting HNO(3) is a metastable entity at the surface of ice. Therefore, despite ionic dissociation of HNO(3) being thermodynamically favored, it appears to be kinetically inhibited at the surface of amorphous solid water at temperatures below 120 K.

  17. 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.

  18. Spectroscopic studies of cryogenic fluids: Benzene in propane

    NASA Astrophysics Data System (ADS)

    Nowak, R.; Bernstein, E. R.

    1987-03-01

    Energy shifts and bandwidths for the 1B2u↔1A1g optical absorption and emission transitions of benzene dissolved in propane are presented as a function of pressure, temperature, and density. Both absorption and emission spectra exhibit shifts to lower energy as a function of density, whereas no shifts are observed if density is kept constant and temperature and pressure are varied simultaneously. Density is thus the fundamental microscopic parameter for energy shifts of optical transitions. The emission half-width is a linear function of both temperature and pressure but the absorption half-width is dependent only upon pressure. These results are interpreted qualitatively in terms of changes occurring in the intermolecular potentials of the ground and excited states. Both changes in shape of and separation between the ground and excited state potentials are considered as a function of density. Classical dielectric (Onsager-Böttcher), microscopic dielectric (Wertheim) and microscopic quantum statistical mechanical (Schweizer-Chandler) theories of solvent effects on solute electronic spectra are compared with the experimental results. Calculations suggest limited applicability of dielectric theories but good agreement between experiment and microscopic theory. The results demonstrate the usefulness of cryogenic solutions for high pressure, low temperature spectroscopic studies of liquids.

  19. Spectroscopic Studies of Dehydrogenation of Ammonia Borane in Carbon Cryogel

    SciTech Connect

    Sepehri, Saghar; Feaver, Aaron M.; Shaw, Wendy J.; Howard, Christopher J.; Zhang, Qifeng; Autrey, Thomas; Cao, Guozhong

    2007-12-27

    The reaction pathways leading to the thermal decomposition of solid state ammonia borane (AB) incorporated in carbon cryogels (CC) have been studied by spectroscopic methods. The time dependent thermal decomposition was followed by in situ 11B NMR and showed a significant increase in hydrogen release kinetics. Both 11B NMR and Fourier Transform Infrared Spectroscopy (FTIR) show new reaction products formed in the thermal decomposition of AB-CC that are assigned to reactions with surface oxygen groups. The results indicate that incorporation of AB in CC enhance kinetics due to reactions with residual surface-bound oxygen functional groups. The formation of new products with surface-O-B bonds is consistent with the greater reaction exothermicity observed when hydrogen is released from AB-CC materials. Scanning electron microscopy (SEM) shows different morphology of AB in ammonia borane – carbon cryogel (AB-CC) nanocomposite as compared to neat AB. Support for this work is provided by NSF (DMR-0605159), WTC, and EnerG2 LLC as well as the DoE Center of Excellence in Chemical Hydrogen Storage funded by the DOE H2 Program. FTIR experiments were performed in Professor Zhang’s lab in MSE department at UW. Part of this research was performed in the William R. Wiley Environmental Molecular Sciences Laboratory, located at the Pacific Northwest National Laboratory, which is operated by the Battelle for the U.S. Department of Energy.

  20. Molecular docking, spectroscopic studies and quantum calculations on nootropic drug.

    PubMed

    Uma Maheswari, J; Muthu, S; Sundius, Tom

    2014-04-05

    A systematic vibrational spectroscopic assignment and analysis of piracetam [(2-oxo-1-pyrrolidineacetamide)] have been carried out using FT-IR and FT-Raman spectral data. The vibrational analysis was aided by an electronic structure calculation based on the hybrid density functional method B3LYP using a 6-311G++(d,p) basis set. Molecular equilibrium geometries, electronic energies, IR and Raman intensities, and harmonic vibrational frequencies have been computed. The assignments are based on the experimental IR and Raman spectra, and a complete assignment of the observed spectra has been proposed. The UV-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies and the maximum absorption wavelengths λmax were determined by the time-dependent DFT (TD-DFT) method. The geometrical parameters, vibrational frequencies and absorption wavelengths were compared with the experimental data. The complete vibrational assignments are performed on the basis of the potential energy distributions (PED) of the vibrational modes in terms of natural internal coordinates. The simulated FT-IR, FT-Raman, and UV spectra of the title compound have been constructed. Molecular docking studies have been carried out in the active site of piracetam by using Argus Lab. In addition, the potential energy surface, HOMO and LUMO energies, first-order hyperpolarizability and the molecular electrostatic potential have been computed.

  1. Spectroscopic measurement of the MHD dynamo in the MST reversed field pinch

    SciTech Connect

    Chapman, James Tharp

    1998-09-01

    The author has directly observed the coupling of ion velocity fluctuations and magnetic field fluctuations to produce an MHD dynamo electric field in the interior of the MST reversed field pinch. Chord averaged ion velocity fluctuations were measured with a fast spectroscopic diagnostic which collects line radiation from intrinsic carbon impurities simultaneously along two lines of sight. The chords employed for the measurements resolved long wavelength velocity fluctuations of several km/s at 8-20 kHz as tiny, fast Doppler shifts in the emitted line profile. During discrete dynamo events the velocity fluctuations, like the magnetic fluctuations, increase dramatically. The toroidal and poloidal chords with impact parameters of 0.3 a and 0.6 a respectively, resolved fluctuation wavenumbers with resonance surfaces near or along the lines of sight indicating a radial velocity fluctuation width for each mode which spans only a fraction of the plasma radius. The phase between the measured toroidal velocity fluctuations and the magnetic fluctuations matches the predictions of resistive MHD while the poloidal velocity fluctuations exhibit a phase consistent with the superposition of MHD effects and the advection of a mean flow gradient past the poloidal line of sight. Radial velocity fluctuations resolved by a chord through the center of the plasma were small compared to the poloidal and toroidal fluctuations and exhibited low coherence with the magnetic fluctuations. The ensembled nonlinear product of the ion velocity fluctuations and fluctuations in the magnetic field indicates a substantial dynamo electric field which peaks during the periods of spontaneous flux generation.

  2. The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular Gas Reservoirs in High-redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Decarli, Roberto; Walter, Fabian; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Elbaz, David; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Bacon, Roland; Bauer, Franz; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Gónzalez-López, Jorge; Inami, Hanae; Ivison, Rob; Hodge, Jacqueline; Karim, Alex; Magnelli, Benjamin; Ota, Kazuaki; Popping, Gergö; Rix, Hans-Walter; Sargent, Mark; van der Wel, Arjen; van der Werf, Paul

    2016-12-01

    We study the molecular gas properties of high-z galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets an ˜1 arcmin2 region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3 and 1 mm bands. Of a total of 1302 galaxies in the field, 56 have spectroscopic redshifts and correspondingly well-defined physical properties. Among these, 11 have infrared luminosities {L}{IR}\\gt {10}11 {L}⊙ , i.e., a detection in CO emission was expected. Out of these, 7 are detected at various significance in CO, and 4 are undetected in CO emission. In the CO-detected sources, we find CO excitation conditions that are lower than those typically found in starburst/sub-mm galaxy/QSO environments. We use the CO luminosities (including limits for non-detections) to derive molecular gas masses. We discuss our findings in the context of previous molecular gas observations at high redshift (star formation law, gas depletion times, gas fractions): the CO-detected galaxies in the UDF tend to reside on the low-{L}{IR} envelope of the scatter in the {L}{IR}{--}{L}{CO}\\prime relation, but exceptions exist. For the CO-detected sources, we find an average depletion time of ˜1 Gyr, with significant scatter. The average molecular-to-stellar mass ratio ({M}{{H}2}/M *) is consistent with earlier measurements of main-sequence galaxies at these redshifts, and again shows large variations among sources. In some cases, we also measure dust continuum emission. On average, the dust-based estimates of the molecular gas are a factor ˜2-5× smaller than those based on CO. When we account for detections as well as non-detections, we find large diversity in the molecular gas properties of the high-redshift galaxies covered by ASPECS.

  3. Photoacoustic FTIR spectroscopic study of undisturbed human cortical bone

    NASA Astrophysics Data System (ADS)

    Gu, Chunju; Katti, Dinesh R.; Katti, Kalpana S.

    2013-02-01

    Chemical pretreatment has been the prevailing sample preparation procedure for infrared (IR) spectroscopic studies on bone. However, experiments have indicated that chemical pretreatment can potentially affect the interactions between the components. Typically the IR techniques have involved transmission experiments. Here we report experimental studies using photoacoustic Fourier transform infrared spectroscopy (PA-FTIR). As a nondestructive technique, PA-FTIR can detect absorbance spectrum from a sample at controllable sampling depth and with little or no sample preparation. Additionally, the coupling inert gas, helium, which is utilized in the PA-FTIR system, can inhibit bacteria growth of bone by displacing oxygen. Therefore, we used this technique to study the undisturbed human cortical bone. It is found that photoacoustic mode (linear-scan, LS-PA-FTIR) can obtain basically similar spectra of bone as compared to the traditional transmission mode, but it seems more sensitive to amide III and ν2 carbonate bands. The ν3 phosphate band is indicative of detailed mineral structure and symmetry of native bone. The PA-FTIR depth profiling experiments on human cortical bone also indicate the influence of water on OH band and the cutting effects on amide I and mineral bands. Our results indicate that phosphate ion geometry appears less symmetric in its undisturbed state as detected by the PA-FTIR as compared to higher symmetry observed using transmission techniques on disturbed samples. Moreover, the PA-FTIR spectra indicate a band at 1747 cm-1 possibly resulting from Cdbnd O stretching of lipids, cholesterol esters, and triglycerides from the arteries. Comparison of the spectra in transverse and longitudinal cross-sections demonstrates that, the surface area of the longitudinal section bone appears to have more organic matrix exposed and with higher mineral stoichiometry.

  4. A spectroscopic study of anomalous stellar populations in M67

    NASA Astrophysics Data System (ADS)

    McGahee, Courtney Elizabeth

    A population of stars exists in the old, open cluster M67, whose photometry, color magnitude diagram locations and associated evolutionary states cannot be explained by current, standard single star evolution theory. These stars are often referred to as "yellow straggler" stars. Yellow stragglers have been identified in multiple star clusters suggesting that these stars constitute a real population. Additionally, according to independent studies, at least some of the yellow straggler stars in M67 are likely cluster members. Therefore, cluster non-membership is not a sufficient explanation for the observed anomalous photometry of these stars. It is possible that the yellow stragglers occupy their precarious color magnitude diagram positions as a result of the evolution of mass transfer blue straggler stars. These are stars which have been formed by Roche Lobe overflow mass transfer in close binary systems. If this the case for the yellow stragglers, it is hypothesized that they could potentially exhibit two spectroscopic characteristics that can be indicative of this type of mass transfer system. Specifically, variable radial velocities can be used to indicate that the yellow stragglers exist in binary systems and enhancements of s-process elements in yellow stragglers can indicate Roche Lobe overflow mass transfer from a once asymptotic giant branch star which has since evolved into a white dwarf. This dissertation details the radial velocity survey and the chemical abundance analysis that have been conducted to investigate the yellow stragglers with regard to this hypothesis. The radial velocity survey revealed that eight of the ten yellow stragglers studied exhibit variable radial velocities indicating that the yellow straggler population of M67 possess a high binary frequency. However, the chemical abundance analysis revealed that none of the yellow stragglers exhibited enhancements of the s-process elements Y and Ba. Therefore, a history which involves Roche

  5. The spectroscopic study of building composites containing natural sorbents

    NASA Astrophysics Data System (ADS)

    Król, M.; Mozgawa, W.

    2011-08-01

    This work presents the results of FT-IR spectroscopic studies of heavy metal cations (Ag +, Pb 2+, Zn 2+, Cd 2+ and Cr 3+) immobilization from aqueous solutions on natural sorbents. The sorption has been conducted on sodium forms of zeolite (clinoptilolite) and clay minerals (mixtures containing mainly montmorillonite and kaolinite) which have been separated from natural Polish deposit. In the next part of the work both sorbents were used to obtain new building composites. It was proven those heavy metal cations' sorption causes changes in IR spectra of the zeolite and clay minerals. These alterations are dependent on the way the cations were sorbed. In the case of zeolite, variations of the bands corresponding to the characteristic ring vibrations have been observed. These rings occur in pseudomolecular complexes 4-4-1 (built of alumino- and silicooxygen tetrahedra) which constitute the secondary building units (SBU) and form spatial framework of the zeolite. The most significant changes have been determined in the region of pseudolattice vibrations (650-700 cm -1). In the instance of clay minerals, changes in the spectra occur at two ranges: 1200-800 cm -1 - the range of the bands assigned to asymmetric Si-O(Si,Al) and bending Al-OH vibrations and 3800-3000 cm -1 - the range of the bands originating from OH - groups stretching vibrations. Next results indicate possibilities of applying the used natural sorbents for the obtainment of new building materials having favourable composition and valuable properties. The zeolite was used for obtaining autoclaved materials with an addition of CaO, and the clay minerals for ceramic sintered materials with an addition of quartz and clinoptilolite were produced. FT-IR studies were also conducted on the obtained materials.

  6. Effect of temperature on the methotrexate BSA interaction: Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Sułkowska, A.; Maciążek, M.; Równicka, J.; Bojko, B.; Pentak, D.; Sułkowski, W. W.

    2007-05-01

    Rheumatoid arthritis (RA) is an autoimmune and chronic inflammatory illness which affects about one percent of the world's population. Methotrexate (4-amino-10-methylfolic acid) (MTX) also known as amethopterin is commonly used to treat rheumatoid arthritis (RA). It is transported in the circulary system as a complex with serum albumin. The aim of this study was to investigate the interactions of MTX with transporting protein with the use of spectroscopic methods. The binding of MTX to bovine serum albumin (BSA) was studied by monitoring the changes in the emission fluorescence spectra of protein in the presence of MTX at excitation wavelength of 280 nm and 295 nm. The quenching of protein fluorescence at temperature range from 298 K to 316 K was observed. Energy transfer between methotrexate and fluorophores contained in the serum albumin structure was found at the molar ratio MTX:BSA 7.5:1. The relative fluorescence intensity of BSA decreases with increase of temperature. Similar results were observed for BSA excited with 280 nm and 295 nm at the same temperature range. The presence of MTX seems to prevent these changes. Temperature dependence of the binding constant has been presented. The binding and quenching constants for equilibrium complex were calculated using Scatchard and Stern-Volmer method, respectively. The results show that MTX forms π-π complex with aromatic amino acid residues of BSA. The binding site for MTX on BSA was found to be situated in the hydrophobic IIA or IB subdomain where the Trps were located. The spontaneity of MTX-BSA complex formation in the temperature range 298-316 K was ascertained.

  7. Spectroscopic study of graphene oxide membranes exposed to ultraviolet light

    SciTech Connect

    Schwenzer, Birgit; Kaspar, Tiffany C.; Shin, Yongsoon; Gotthold, David W.

    2016-05-16

    Research on graphene oxide (GO) as anything but a precursor material for synthesizing graphene started to pick up in 20061,2 and was soon followed by a first report of freestanding GO membranes (also referred to as GO paper) from R. S. Ruoff’s group at Northwestern University.3 The first GO membranes were prepared by vacuum filtration. More recently, larger scale GO membranes have been prepared by tape casting4 and other methods.5 In step with the development of new fabrication techniques, GO membranes are now tested for a wide array of applications6 ranging from energy-related4,7 or biomedical8 applications to more conventional uses for filtration9 and dehumidification.10 For all these proposed and implemented applications it remains to be seen how sensitive each of them is with respect to chemical and physical changes of the GO membranes over time. In this study, we report the effects of UV exposure on 2D-hierarchically stacked (Fig. S1 in ESI†) GO membranes. Macroscopically observable changes, such as darkening and mechanical deformation, have been correlated to chemical changes at the molecular level through spectroscopic measurements. Not only do the results of this work offer insights into the stability of GO membranes under UV light, but the findings will enable researchers, who are studying the use of these materials for different applications, to better understand the shelf life and packaging requirements for GO membranes. Furthermore, our results demonstrate the feasibility of deep ultraviolet (DUV) photolithography for graphene oxide-based devices. This approach is readily scalable as opposed to previous reports on photolithographic patterned reduction of GO to graphene by AFM,11 electron-beam12 or with an extreme ultraviolet (λ = 46.9 nm) laser.13

  8. 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...

  9. Optical and spectroscopic study of erbium doped calcium borotellurite glasses

    NASA Astrophysics Data System (ADS)

    Gomes, J. F.; Lima, A. M. O.; Sandrini, M.; Medina, A. N.; Steimacher, A.; Pedrochi, F.; Barboza, M. J.

    2017-04-01

    In this study, 10CaF2 - (29.9-0.4x)CaO - (60-0.6x)B2O3 - xTeO2 - 0,1Er2O3 (x = 10, 16, 22, 30 and 50 mol %) glasses were synthesized, and their optical and spectroscopic properties were investigated. X-ray diffraction, density, glass transition temperature (Tg), crystallization temperature (Tx), refraction index, luminescence, radiative lifetime and optical absorption measurements were carried out. Molar volume (Vm), thermal stability (Tx-Tg), electronic polarizability (αm), optical bang gap energy (Eg) and Judd-Ofelt (JO) parameters Ωt (2,4,6) were also calculated. The results are discussed in terms of tellurium oxide content. The increase of TeO2 in the glasses composition increases density, refractive index and electronic polarizability. The optical band gap energy decreases varying from 3.37 to 2.71 eV for the glasses with 10 and 50 mol% of TeO2, respectively. The optical absorption coefficient spectra show characteristic bands of Er3+ ions. Furthermore, these spectra in NIR region show a decrease of hydroxyl groups as a function of TeO2 addition. Luminescence intensity and radiative lifetimes at 1530 nm show an increasing with the TeO2 content. The JO parameters of Er:CaBTeX glasses follow the trend Ω2 > Ω4 > Ω6 and the quality factor values (Ω4/Ω6) were between 1.37 and 3.07. By comparing the measured lifetime with the calculated radiative decay time, quantum efficiency was calculated. The luminescence emission intensity at 1530 nm decreases with the increase of temperature. The lifetime values show a slight trend to decrease with the temperature increase, from 300 to 420 K, for all the samples.

  10. Spectroscopic Study on Ultrafast Carrier Dynamics and Terahertz Amplified Stimulated Emission in Optically Pumped Graphene

    NASA Astrophysics Data System (ADS)

    Otsuji, Taiichi; Boubanga-Tombet, Stephane; Satou, Akira; Suemitsu, Maki; Ryzhii, Victor

    2012-08-01

    This paper reviews recent advances in spectroscopic study on ultrafast carrier dynamics and terahertz (THz) stimulated emission in optically pumped graphene. The gapless and linear energy spectra of electrons and holes in graphene can lead to nontrivial features such as negative dynamic conductivity in the THz spectral range, which may lead to the development of new types of THz lasers. First, the non-equilibrium carrier relaxation/recombination dynamics is formulated to show how photoexcited carriers equilibrate their energy and temperature via carrier-carrier and carrier-phonon scatterings and in what photon energies and in what time duration the dynamic conductivity can take negative values as functions of temperature, pumping photon energy/intensity, and carrier relaxation rates. Second, we conduct time-domain spectroscopic studies using an optical pump and a terahertz probe with an optical probe technique at room temperature and show that graphene sheets amplify an incoming terahertz field. Two different types of samples are prepared for the measurement; one is an exfoliated monolayer graphene on SiO2/Si substrate and the other is a heteroepitaxially grown non-Bernal stacked multilayer graphene on a 3C-SiC/Si epi-wafer.

  11. Spectroscopic studies of cathode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Totir, Dana Alexa

    2000-10-01

    Structural changes that occur during electrochemical cycling of lithium-ion battery cathode materials have been investigated using in situ spectroscopic techniques. A new method was developed for the preparation of carbon and binder free cathodes utilizing powder materials of interest for commercial batteries. The extraordinary quality of the cyclic voltammetric curves recorded for this type of electrodes during the in situ measurements allows direct correlations to be made between the state of charge of the material and its structural and electronic characteristics. LiCoO2, LiMn2O4 and LiCo0.15Ni 0.85O2 electrodes were evaluated using cycling voltammetry and the mean diffusion coefficient for Li-ions in the lattice (DLi) was calculated for LiMn2O4. LiMn2O4 electrodes prepared by this technique have been studied in situ using Mn K-edge XAS. Data analysis for the species formed at different potentials indicated a contraction of the lattice associated with the increase in the oxidation state of manganese. In situ Raman spectra of particles of LiMn2O 4, and LiCoO2 embedded in Au and also of KS-44 graphite and carbon microfibers MCF28 embedded in thermally annealed Ni have been recorded as a function of the applied potential. Fe K-edge XAFS of pyrite electrodes in a Li/PEO(LiClO4)/FeS 2 cell and S K-edge XANES measurements of a FeS2 electrode in a non-aqueous electrolyte have been acquired as a function of the state of charge. The studies have clearly evidenced the formation of metallic Fe and Li2S as intermediates after 4 e- discharge and the formation of Li2FeS2 after 2 e- recharge. While Fe K-edge studies have indicated that there is no change in the Fe environment and oxidation state upon 4 e- recharge, the results obtained from S K-edge studies are inconclusive for this stage. Finally, in situ Co K-edge XAFS data were obtained for the first time during the electrochemical cycling of electrodeposited Co(OH) 2 films in alkaline solutions. The results support

  12. Spectroscopic studies of uranium species for environmental decontamination applications

    NASA Astrophysics Data System (ADS)

    Eng, Charlotte

    After the Cold War, Department of Energy began to concentrate its efforts on cleanup of former nuclear material processing facilities, especially uranium-contaminated groundwater and soil. This research aims to study uranium association to both organic and inorganic compounds found in the contaminated environment in the hopes that the information gathered can be applied to the development and optimization of cost-effective remediation techniques. Spectroscopic and electrochemical methods will be employed to examine the behavior of uranium in given conditions to further our understanding of its impact on the environment. Uranium found in groundwater and soil bind with various ligands, especially organic ligands present in the environment due to natural sources (e.g. metabolic by-products or degradation of plants and animals) or man-made sources (e.g. chelating agents used in operating or cleanup of uranium processing facilities). We selected reasonable analogs of naturally occurring matter and studied their structure, chemical and electrochemical behavior and found that the structure of uranyl complexes depends heavily on the nature of the ligand and environmental factors such as pH. Association of uranium-organic complexes with anaerobic bacteria, Clostridium sp. was studied to establish if the bacteria can effectively bioreduce uranium while going through normal bacterial activity. It was found that the nature of the organic ligand affected the bioavailability and toxicity of the uranium on the bacteria. In addition, we have found that the type of iron corrosion products and uranyl species present on the surface of corroded steel depended on various environmental factors, which subsequently affected the removal rate of uranium by a citric acid/hydrogen peroxide/deionized water cleaning process. The method was found to remove uranium from only the topmost corrosion layers and residual uranium could be found (a) deeper in the corrosion layers where it is occluded by

  13. X-ray spectroscopic studies of secondary battery materials

    NASA Astrophysics Data System (ADS)

    Kostov, Svilen Dimitar

    1998-09-01

    X-ray spectroscopic methods, both NEXAFS and EXAFS were used in the study of the structural and electronic properties of different types of new battery materials. NEXAFS analysis of the spectra of Lisb{1-x}CoO2 secondary battery cathodes revealed that the addition of Li proceeds is strongly correlated to the increase in electronic charge on the Co ion. A structural phase transition is confirmed for x=0.5. The presence of Mnsp{+2} is detected in the conventionally made LiMnOsb2 cathodes but not in ones prepared according to the new ADL process. Lisb{x}Vsb6Osb{13} cathode material, where 0≤ x≤6, was measured using x-ray absorption, EPR and NMR techniques. The intercalation mechanism involves a conversion of Vsp{+5} to Vsp{+4} in Vsb6Osb{13} until the composition Lisb2Vsb6Osb{13} is reached. Further addition of lithium is accompanied by the conversion of Vsp{+4} to Vsp{+3} until Lisb8Vsb6Osb{13} is reached. The process is complicated and involves structural phase changes and increasing structural disorder within the multi-phase system as Li concentration is increased. Studies of LiNi/CoOsb2 intercalation cathodes prepared by a novel sol-gel technique suggests that although the partial substitution of Co for Ni stabilizes the system by removing Nisp{+2}, a Jahn-Teller type structural distortion in the predominantly Nisp{=3} system persists. In-situ EXAFS measurements of the pyrite cathode in a new Li/CPE/FeSsb2 showed two distinct environments of the Fe ion, which were interpreted as those of metallic Fe and residual FeSsb2 at high lithium concentration, and Lisb2FeSsb2 and residual FeSsb2 at low lithium concentration. The formation of FeS was not detected. A new type of hydrogen ion battery incorporating a MnSOsb4sp&*slash;Hsb2O based cathode and polymer electrolyte was also studied. Heavily cycled and discharged cathodes showed an almost identical Mn local structure to that of single cycled ones. The Mn environment becomes very different in the charged cathodes

  14. Spectroscopic Studies of the Several Isomers of UO3

    SciTech Connect

    Sweet, Lucas E.; Reilly, Dallas D.; Abrecht, David G.; Buck, Edgar C.; Meier, David E.; Su, Yin-Fong; Brauer, Carolyn S.; Schwantes, Jon M.; Tonkyn, Russell G.; Szecsody, James E.; Blake, Thomas A.; Johnson, Timothy J.

    2013-09-26

    Uranium trioxide is known to adopt seven different structural forms. While these structural forms have been well characterized using x-ray or neutron diffraction techniques, little work has been done to characterize their spectroscopic properties, particularly of the pure phases. Since the structural isomers of UO3 all have similar thermodynamic stabilities and most tend to hydrolyze under open atmospheric conditions, mixtures of UO3 phases and the hydrolysis products are common. Much effort went into isolating pure phases of UO3. Utilizing x-ray diffraction as a sample identification check, UV/Vis/NIR spectroscopic signatures of α-UO3, β-UO3, γ-UO3 and UO2(OH)2 products were obtained. The spectra of the pure phases can now be used to characterize typical samples of UO3, which are often mixtures of isomers.

  15. Structural, spectroscopic and theoretical study of novel ephedrinum salt

    NASA Astrophysics Data System (ADS)

    Ivanova, B.; Kolev, T.; Lamshöft, M.; Mayer-Figge, H.; Seidel, R.; Sheldrick, W. S.; Spiteller, M.

    2010-05-01

    Ephedrinum violurate dihydrate was synthesized, spectroscopically and structural elucidated. The data are compared with those of the free-base ephedrine hemihydrate. Discussion on the stable conformer of the ephedrinum cation is carried out. Quantum chemical calculations were performed for the theoretical elucidation of the conformational preference of the ephedrinum cation and its vibrational properties. The model systems neutral ephedrine hemihydrate ( 1) and violurate salt dihydrate ( 2) are elucidated.

  16. A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: the Group Catalog

    NASA Astrophysics Data System (ADS)

    Wilson, Michelle L.; Zabludoff, Ann I.; Ammons, S. Mark; Momcheva, Ivelina G.; Williams, Kurtis A.; Keeton, Charles R.

    2016-12-01

    With a large, unique spectroscopic survey in the fields of 28 galaxy-scale strong gravitational lenses, we identify groups of galaxies in the 26 adequately sampled fields. Using a group-finding algorithm, we find 210 groups with at least 5 member galaxies; the median number of members is 8. Our sample spans redshifts of 0.04 ≤ z grp ≤ 0.76 with a median of 0.31, including 174 groups with 0.1 < z grp < 0.6. The groups have radial velocity dispersions of 60 ≤ σ grp ≤ 1200 km s-1 with a median of 350 km s-1. We also discover a supergroup in field B0712+472 at z = 0.29 that consists of three main groups. We recover groups similar to ˜85% of those previously reported in these fields within our redshift range of sensitivity and find 187 new groups with at least five members. The properties of our group catalog, specifically, (1) the distribution of σ grp, (2) the fraction of all sample galaxies that are group members, and (3) the fraction of groups with significant substructure, are consistent with those for other catalogs. The distribution of group virial masses agrees well with theoretical expectations. Of the lens galaxies, 12 of 26 (46%) (B1422+231, B1600+434, B2114+022, FBQS J0951+2635, HE0435-1223, HST J14113+5211, MG0751+2716, MGJ1654+1346, PG 1115+080, Q ER 0047-2808, RXJ1131-1231, and WFI J2033-4723) are members of groups with at least five galaxies, and one more (B0712+472) belongs to an additional, visually identified group candidate. There are groups not associated with the lens that still are likely to affect the lens model; in six of 25 (24%) fields (excluding the supergroup), there is at least one massive (σ grp ≥ 500 km s-1) group or group candidate projected within 2‧ of the lens.

  17. NMR spectroscopic study of organic phosphate esters coprecipitated with calcite

    NASA Astrophysics Data System (ADS)

    Phillips, Brian L.; Zhang, Zelong; Kubista, Laura; Frisia, Silvia; Borsato, Andrea

    2016-06-01

    Organic phosphorus incorporated in calcite during laboratory precipitation experiments and in natural cave deposits was investigated by solid-state NMR spectroscopy. For calcite precipitated in the presence of organic phosphoesters of varying size and functionality, solid-state 31P{1H} CP/MAS NMR shows that the phosphoesters were incorporated intact into the solid. Systematic changes in the 31P NMR chemical shift of the phosphate group were observed between the solid phosphoester and that incorporated in the solid precipitate, yielding 31P NMR chemical shifts of the coprecipitates in the range of +1.8 to -2.2 ppm. These chemical shifts are distinct from that of similarly prepared calcite coprecipitated with inorganic phosphate, 3.5 ppm. Only minor changes were noted in the phosphoester 31P chemical shift anisotropy (CSA) which suggests no significant change in the local structure of the phosphate group, which is dominated by C-O-P bonding. Close spatial proximity of the organic phosphate group to calcite structural components was revealed by 31P/13C rotational echo double resonance (REDOR) experiments for coprecipitates prepared with 13C-labeled carbonate. All coprecipitates showed significant 31P dephasing effects upon 13C-irradiation, signaling atomic-scale proximity to carbonate carbon. The dephasing rate for smaller organophosphate molecules is similar to that observed for inorganic phosphate, whereas much slower dephasing was observed for larger molecules having long and/or bulky side-chains. This result suggests that small organic molecules can be tightly enclosed within the calcite structure, whereas significant structural disruption required to accommodate the larger organic molecules leads to longer phosphate-carbonate distances. Comparison of 31P NMR spectroscopic data from the synthetic coprecipitates with those from calcite moonmilk speleothems indicates that phosphorus occurs mainly as inorganic orthophosphate in the natural deposits, although small

  18. A Raman Spectroscopic Study of Kernite to 25 GPa

    NASA Astrophysics Data System (ADS)

    Silva, M. E.; O'Bannon, E. F., III; Williams, Q. C.

    2015-12-01

    A Raman spectroscopic study of kernite to 25 GPaMarcus Silva, Earl O'Bannon III, and Quentin Williams Department of Earth & Planetary Sciences, University of California Santa Cruz The Raman spectrum of kernite (Na2B4O6(OH)2·3(H2O)) has been characterized up to ~25 GPa in order to explore pressure-induced changes in a structurally novel mineral that contains mixed coordination borate groups (three- and four-fold), and both hydroxyl units and water. During compression, all of the ~30 modes monitored shift positively and monotonically until ~2.2 GPa where a few low frequency modes disappear and tetrahedral borate modes merge. The low frequency modes that disappear at ~2.2 GPa are likely associated with Na vibrations, and their disappearance suggests that dramatic changes occur in the Na sites at ~2.2 GPa. The merging of the boron bending and stretching modes at ~2.2 GPa suggests that the local symmetry of the BO4 tetrahedra changes at this pressure, and likely becomes more symmetric. The remaining modes shift positively up to ~7.4 GPa where a second notable change occurs. All but 5 modes (with initial frequencies of 150, 166, 289, 307, and 525 cm-1) disappear at ~7.4 GPa. This indicates that a second phase transition has occurred which affects both the BO3H and BO4­ groups: based on the loss of modes, this transition may be associated with disordering of the crystal. These 5 modes persist and shift monotonically up to ~25 GPa. On decompression, the 5 modes shift smoothly down to ~2.0 GPa where a few new modes appear in the spectrum. When fully decompressed to room pressure, the Raman spectrum of the recovered sample is significantly different from the ambient spectrum of the initial sample. Thus, our results are suggest a phase transition occurring at 2.2 GPa with changes in the Na and tetrahedral boron sites, followed by an additional transition at 7.4 GPa that may involve disordering of the crystal. In the latter transition, at least the BO3H groups appear to be

  19. Pilot Field Test Study

    NASA Technical Reports Server (NTRS)

    Sherriff, Abigail

    2015-01-01

    The Field Test study is currently in full swing, preceded by the successful completion of the Pilot Field Test study that paved the way for collecting data on the astronauts in the medical tent in Kazakhstan. Abigail Sherriff worked alongside Logan Dobbe on one Field Test aspect to determine foot clearance over obstacles (5cm, 10cm, and 15cm) using APDM Inc. Internal Measurement Units (IMU) worn by the astronauts. They created a program to accurately calculate foot clearance using the accelerometer, magnetometer, and gyroscope data with the IMUs attached to the top of the shoes. To validate the functionality of their program, they completed a successful study on test subjects performing various tasks in an optical motion studio, considered a gold standard in biomechanics research. Future work will include further validation and expanding the program to include other analyses.

  20. 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.

  1. Vibrational Frequencies and Spectroscopic Constants for 1(sup 3)A' HNC and 1(sup 3)A' HOC+ from High-Accuracy Quartic Force Fields

    NASA Technical Reports Server (NTRS)

    Fortenberry, Ryan C.; Crawford, T. Daniel; Lee, Timothy J.

    2014-01-01

    The spectroscopic constants and vibrational frequencies for the 1(sup 3)A' states of HNC, DNC, HOC+, and DOC+ are computed and discussed in this work. The reliable CcCR quartic force field based on high-level coupled cluster ab initio quantum chemical computations is exclusively utilized to provide the anharmonic potential. Then, second order vibrational perturbation theory and vibrational configuration interaction methods are employed to treat the nuclear Schroedinger equation. Second-order perturbation theory is also employed to provide spectroscopic data for all molecules examined. The relationship between these molecules and the corresponding 1(sup 3)A' HCN and HCO+ isomers is further developed here. These data are applicable to laboratory studies involving formation of HNC and HOC+ as well as astronomical observations of chemically active astrophysical environments.

  2. 3D-HST: A WIDE-FIELD GRISM SPECTROSCOPIC SURVEY WITH THE HUBBLE SPACE TELESCOPE

    SciTech Connect

    Brammer, Gabriel B.; Van Dokkum, Pieter G.; Skelton, Rosalind E.; Nelson, Erica; Bezanson, Rachel; Leja, Joel; Lundgren, Britt; Franx, Marijn; Fumagalli, Mattia; Patel, Shannon; Labbe, Ivo; Rix, Hans-Walter; Schmidt, Kasper B.; Da Cunha, Elisabete; Kriek, Mariska; Erb, Dawn K.; Fan, Xiaohui; Foerster Schreiber, Natascha; Illingworth, Garth D.; Magee, Dan; and others

    2012-06-01

    We present 3D-HST, a near-infrared spectroscopic Treasury program with the Hubble Space Telescope for studying the physical processes that shape galaxies in the distant universe. 3D-HST provides rest-frame optical spectra for a sample of {approx}7000 galaxies at 1 < z < 3.5, the epoch when {approx}60% of all star formation took place, the number density of quasars peaked, the first galaxies stopped forming stars, and the structural regularity that we see in galaxies today must have emerged. 3D-HST will cover three quarters (625 arcmin{sup 2}) of the CANDELS Treasury survey area with two orbits of primary WFC3/G141 grism coverage and two to four orbits with the ACS/G800L grism in parallel. In the IR, these exposure times yield a continuum signal-to-noise ratio of {approx}5 per resolution element at H{sub 140} {approx} 23.1 and a 5{sigma} emission-line sensitivity of {approx}5 Multiplication-Sign 10{sup -17} erg s{sup -1} cm{sup -2} for typical objects, improving by a factor of {approx}2 for compact sources in images with low sky background levels. The WFC3/G141 spectra provide continuous wavelength coverage from 1.1 to 1.6 {mu}m at a spatial resolution of {approx}0.''13, which, combined with their depth, makes them a unique resource for studying galaxy evolution. We present an overview of the preliminary reduction and analysis of the grism observations, including emission-line and redshift measurements from combined fits to the extracted grism spectra and photometry from ancillary multi-wavelength catalogs. The present analysis yields redshift estimates with a precision of {sigma}(z) = 0.0034(1 + z), or {sigma}(v) Almost-Equal-To 1000 km s{sup -1}. We illustrate how the generalized nature of the survey yields near-infrared spectra of remarkable quality for many different types of objects, including a quasar at z = 4.7, quiescent galaxies at z {approx} 2, and the most distant T-type brown dwarf star known. The combination of the CANDELS and 3D-HST surveys will

  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. Spectroscopic study of the extremely fast rotating star 44 Geminorum

    NASA Astrophysics Data System (ADS)

    Iliev, L.; Vennes, S.; Kawka, A.; Kubat, J.; Nemeth, P.; Borisov, G.; KRaus, M.

    Stars with extremely fast rotation represent interesting challenge to modern understanding of the stellar evolution. The reasons why such a spin-up process should occur during the evolution to otherwise normal star are still not well understood. Already in the beginning of the XX century Otto Struve proposed that fast rotation of the group of stars spectroscopically classified as Be could be the main reason for the formation of observed disks of circumstellar material around them. This circumstellar material is responsible for the emission lines observed in the spectrum of Be-stars as well as for the whole complex of spectral and photometrical patterns called in general Be-phenomenon.

  5. Spectroscopic and dynamical studies of highly energized small polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Stimulated emission pumping (SEP) spectroscopy was used on acetylene and on formyl radical. An attempt was made for pattern recognition based on statistics; a method was invented that combined CNPI (complete nuclear permutation-inversion) group theory and SCC (spectral cross-correlation). But the direction away from statistical pattern recognition back to traditional spectroscopic pattern recognition was taken. Vibrational states and quantum numbers are discussed. For the formyl radical, the fluorescence excitation spectrum was recorded and a rotational analysis of the 0(sup 0)(sub 0) band performed.

  6. Microbial field pilot study

    SciTech Connect

    Knapp, R.M.; McInerney, M.J.; Menzie, D.E.

    1991-12-06

    The objective of this project is to perform a microbial enhanced oil recovery field pilot test in the Southeast Vassar Vertz Sand Unit (SEVVSU) in Payne County, Oklahoma. Indigenous, anaerobic, nitrate-reducing bacteria will be stimulated to selectively plug flow paths which have been preferentially swept by a prior waterflood. This will force future flood water to invade bypassed regions of the reservoir and increase sweep efficiency. During this quarter an additional tracer study was performed in the field to determine pre-treatment flow paths and the first nutrients were injected. 2 figs.

  7. Field studies courses open

    NASA Astrophysics Data System (ADS)

    Fourteen month-long courses combining applied academics with training in field research methodology are being offered this summer by the School for Field Studies. The courses, held in eight countries during May, June, July, and August, provide unique opportunities for participants to work as a team under primitive conditions.‘Our courses bind together the academic challenge of the research problem, the physical challenge of the site itself, and the interpersonal challenge of the expedition team in a dynamic way so that both cognitive and affective learning are accelerated,’ according to Jim Elder, the school's director.

  8. Microbial field pilot study

    SciTech Connect

    Knapp, R.M.; McInerney, M.J.; Menzie, D.E.; Coates, J.D.; Chisholm, J.L.

    1993-05-01

    A multi-well microbially enhanced oil recovery field pilot has been performed in the Southeast Vassar Vertz Sand Unit in Payne County, Oklahoma. The primary emphasis of the experiment was preferential plugging of high permeability zones for the purpose of improving waterflood sweep efficiency. Studies were performed to determine reservoir chemistry, ecology, and indigenous bacteria populations. Growth experiments were used to select a nutrient system compatible with the reservoir that encouraged growth of a group of indigenous nitrate-using bacteria and inhibit growth of sulfate-reducing bacteria. A specific field pilot area behind an active line drive waterflood was selected. Surface facilities were designed and installed. Injection protocols of bulk nutrient materials were prepared to facilitate uniform distribution of nutrients within the pilot area. By the end of December, 1991, 82.5 tons (75.0 tonnes) of nutrients had been injected in the field. A tracer test identified significant heterogeneity in the SEVVSU and made it necessary to monitor additional production wells in the field. The tracer tests and changes in production behavior indicate the additional production wells monitored during the field trial were also affected. Eighty two and one half barrels (13.1 m[sup 3]) of tertiary oil have been recovered. Microbial activity has increased CO[sub 2] content as indicated by increased alkalinity. A temporary rise in sulfide concentration was experienced. These indicate an active microbial community was generated in the field by the nutrient injection. Pilot area interwell pressure interference test results showed that significant permeability reduction occurred. The interwell permeabilities in the pilot area between the injector and the three pilot production wells were made more uniform which indicates a successful preferential plugging enhanced oil recovery project.

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-12-10

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

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

    SciTech Connect

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

    2014-09-10

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

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

    DOE PAGES

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

    2014-09-10

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

  13. A Spectroscopic Study of Anomalous Stellar Populations in M67

    NASA Astrophysics Data System (ADS)

    McGahee, Courtney; King, Jeremy R.; Deliyannis, Constantine P.

    2015-01-01

    A population of so-called "yellow straggler" stars occupy precarious color magnitude diagram positions in the old open cluster M67 that cannot be explained by standard single star evolution theory. These stars may have been formed by Roche lobe overflow mass transfer in close binary systems. We present new radial velocities and spectroscopic abundances of M67 yellow stragglers to test this hypothesis, and find that these objects possess a high binary frequency, but no enhancements of s-process elements that might be a smoking gun signature of mass transfer. Observations were conducted using the WIYN 3.5 m telescope in conjunction with the HYDRA spectrograph at Kitt Peak National Observatory. Support for this project was provided by NSF grants AST 09-08342, AST 0607567, and AST 1211699.

  14. Spectroscopic study of Er:Sm doped barium fluorotellurite glass.

    PubMed

    Bahadur, A; Dwivedi, Y; Rai, S B

    2010-09-15

    In this paper, we report the physical and spectroscopic properties of Er(3+), Sm(3+) and Er(3+):Sm(3+) ions codoped barium fluorotellurite (BFT) glasses. Different Stokes and anti-Stokes emissions were observed under 532 nm and 976 nm laser excitations. Energy transfer from Er(3+) ion to Sm(3+) ion was confirmed on the basis of luminescence intensity variation and decay curve analysis in both the cases. Under green (532 nm) excitation emission intensity of Sm(3+) ion bands improves whereas on NIR (976 nm) excitation new emission bands of Sm(3+) ions were observed in Er:Sm codoped samples. Ion interactions and the different energy transfer parameters were also calculated.

  15. Microbial Field Pilot Study

    SciTech Connect

    Knapp, R.M.; McInerney, M.J.; Menzie, D.E.; Chisholm, J.L.

    1990-11-01

    This report covers progress made during the first year of the Microbial Field Pilot Study project. Information on reservoir ecology and characterization, facility and treatment design, core experiments, bacterial mobility, and mathematical modeling are addressed. To facilitate an understanding of the ecology of the target reservoir analyses of the fluids which support bacteriological growth and the microbiology of the reservoir were performed. A preliminary design of facilities for the operation of the field pilot test was prepared. In addition, procedures for facilities installation and for injection treatments are described. The Southeast Vassar Vertz Sand Unit (SEVVSU), the site of the proposed field pilot study, is described physically, historically, and geologically. The fields current status is presented and the ongoing reservoir simulation is discussed. Core flood experiments conducted during the last year were used to help define possible mechanisms involved in microbial enhanced oil recovery. Two possible mechanisms, relative permeability effects and changes in the capillary number, are discussed and related to four Berea core experiments' results. The experiments were conducted at reservoir temperature using SEVVSU oil, brine, and bacteria. The movement and activity of bacteria in porous media were investigated by monitoring the growth of bacteria in sandpack cores under no flow conditions. The rate of bacteria advancement through the cores was determined. A mathematical model of the MEOR process has been developed. The model is a three phase, seven species, one dimensional model. Finite difference methods are used for solution. Advection terms in balance equations are represented with a third- order upwind differencing scheme to reduce numerical dispersion and oscillations. The model is applied to a batch fermentation example. 52 refs., 26 figs., 21 tabs.

  16. Microbial field pilot study

    SciTech Connect

    Knapp, R.M.; McInerney, M.J.; Menzie, D.E.; Chisholm, J.L.

    1992-03-01

    The objective of this project is to perform a microbial enhanced oil recovery field pilot in the Southeast Vassar Vertz Sand Unit (SEVVSU) in Payne County, Oklahoma. Indigenous, anaerobic, nitrate reducing bacteria will be stimulated to selectively plug flow paths which have been referentially swept by a prior waterflood. This will force future flood water to invade bypassed regions of the reservoir and increase sweep efficiency. This report covers progress made during the second year, January 1, 1990 to December 31, 1990, of the Microbial Field Pilot Study project. Information on reservoir ecology, surface facilities design, operation of the unit, core experiments, modeling of microbial processes, and reservoir characterization and simulation are presented in the report. To better understand the ecology of the target reservoir, additional analyses of the fluids which support bacteriological growth and the microbiology of the reservoir were performed. The results of the produced and injected water analysis show increasing sulfide concentrations with respect to time. In March of 1990 Mesa Limited Partnership sold their interest in the SEVVSU to Sullivan and Company. In April, Sullivan and Company assumed operation of the field. The facilities for the field operation of the pilot were refined and implementation was begun. Core flood experiments conducted during the last year were used to help define possible mechanisms involved in microbial enhanced oil recovery. The experiments were performed at SEVVSU temperature using fluids and inoculum from the unit. The model described in last year's report was further validated using results from a core flood experiment. The model was able to simulate the results of one of the core flood experiments with good quality.

  17. Microbial field pilot study

    SciTech Connect

    Knapp, R.M.; McInerney, M.J.; Menzie, D.E.; Chisholm, J.L.

    1992-03-01

    The objective of this project is to perform a microbial enhanced oil recovery field pilot in the Southeast Vassar Vertz Sand Unit (SEVVSU) in Payne County, Oklahoma. Indigenous, anaerobic, nitrate reducing bacteria will be stimulated to selectively plug flow paths which have been referentially swept by a prior waterflood. This will force future flood water to invade bypassed regions of the reservoir and increase sweep efficiency. This report covers progress made during the second year, January 1, 1990 to December 31, 1990, of the Microbial Field Pilot Study project. Information on reservoir ecology, surface facilities design, operation of the unit, core experiments, modeling of microbial processes, and reservoir characterization and simulation are presented in the report. To better understand the ecology of the target reservoir, additional analyses of the fluids which support bacteriological growth and the microbiology of the reservoir were performed. The results of the produced and injected water analysis show increasing sulfide concentrations with respect to time. In March of 1990 Mesa Limited Partnership sold their interest in the SEVVSU to Sullivan and Company. In April, Sullivan and Company assumed operation of the field. The facilities for the field operation of the pilot were refined and implementation was begun. Core flood experiments conducted during the last year were used to help define possible mechanisms involved in microbial enhanced oil recovery. The experiments were performed at SEVVSU temperature using fluids and inoculum from the unit. The model described in last year`s report was further validated using results from a core flood experiment. The model was able to simulate the results of one of the core flood experiments with good quality.

  18. Spectroscopic and computational studies of spin states of iron(IV) nitrido and imido complexes

    DOE PAGES

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

    2017-04-05

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

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

    PubMed

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

    2017-04-05

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

  20. Optical properties of InN studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Chunya, Ye; Wei, Lin; Jin, Zhou; Shuping, Li; Li, Chen; Heng, Li; Xiaoxuan, Wu; Songqing, Liu; Junyong, Kang

    2016-10-01

    With recently developed InN epitaxy via a controlling In bilayer, spectroscopic ellipsometry (SE) measurements had been carried out on the grown InN and the measured ellipsometric spectra were fitted with the Delta Psi2 software by using a suitable model and the dispersion rule. The thickness was measured by a scanning electron microscope (SEM). Insight into the film quality of InN and the lattice constant were gained by X-ray diffraction (XRD). By fitting the SE, the thickness of the InN film is consistent with that obtained by SEM cross-sectional thickness measurement. The optical bandgap of InN was put forward to be 1.05 eV, which conforms to the experimental results measured by the absorption spectrum and cathodoluminescence (CL). The refractive index and the extinction coefficient of interest were represented for InN, which is useful to design optoelectronic devices. Project supported by the State Key Development Program for Basic Research of China (No. 2012CB619301), the National High Technology Research and Development Program of China (No. 2014AA032608), the National Natural Science Foundation of China (Nos. 11204254, 11404271), and the Fundamental Research Funds for the Central Universities (Nos. 2012121014, 20720150027).

  1. Dielectric and impedance spectroscopic studies of neodymium gallate

    NASA Astrophysics Data System (ADS)

    Sakhya, Anup Pradhan; Dutta, Alo; Sinha, T. P.

    2016-05-01

    The AC electrical properties of a polycrystalline neodymium gallate, NdGaO3 (NGO), synthesized by the sol-gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.

  2. Acid doping of polyaniline: Spectroscopic and electrochemical studies

    SciTech Connect

    Hatchett, D.W.; Josowicz, M.; Janata, J.

    1999-12-16

    A detailed investigation of the acid doping behavior of polyaniline has led to a robust and reproducible procedure for controlled adjustment of the redox state of dry polyaniline films. The initial step in this procedure is the casting of PANI films from formic acid. The subsequent exchange of the trapped formic acid for other primary dopants obtained from mono- and polyprotic acids (e.g., CH{sub 3}COO{sup {minus}}, BF{sub 4}{sup {minus}}, HSO{sub 4}{sup {minus}}, SO{sub 4}{sup 2{minus}}, H{sub 2}PO{sub 4}{sup {minus}}, and HPO{sub 4}{sup 2{minus}}) is demonstrated. The voltammetric and the spectroscopic behavior of the PANI doped with different anions indicate that both the protons and the anions of dopant acids influence the structure and redox properties of the polymer. The redox state of PANI doped with homologous series of chloroacetic and carboxylic acids correlates with the pK{sub a} of the dopant acid. These results show that it is possible to prepare the polymer with a desired oxidation state according to the pK{sub a} of the dopant acid of a given homologous series. The exchange of the formic acid for both stronger and weaker doping acid can be repeatedly accomplished by electrochemical cycling.

  3. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-08-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:1 HF dip without rinse, the Si(100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si(100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface-layer, after being heated to approximately 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  4. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-06-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effect of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that, after a 20-sec 9:1 HF dip without rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum chamber (UHV), and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface layer, after being heated to about 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  5. Impedance and modulus spectroscopic study of nano hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Jogiya, B. V.; Jethava, H. O.; Tank, K. P.; Raviya, V. R.; Joshi, M. J.

    2016-05-01

    Hydroxyapatite (Ca10 (PO4)6 (OH)2, HAP) is the main inorganic component of the hard tissues in bones and also important material for orthopedic and dental implant applications. Nano HAP is of great interest due to its various bio-medical applications. In the present work the nano HAP was synthesized by using surfactant mediated approach. Structure and morphology of the synthesized nano HAP was examined by the Powder XRD and TEM. Impedance study was carried out on pelletized sample in a frequency range of 100Hz to 20MHz at room temperature. The variation of dielectric constant, dielectric loss, and a.c. conductivity with frequency of applied field was studied. The Nyquist plot as well as modulus plot was drawn. The Nyquist plot showed two semicircle arcs, which indicated the presence of grain and grain boundary effect in the sample. The typical behavior of the Nyquist plot was represented by equivalent circuit having two parallel RC combinations in series.

  6. Photometric and spectroscopic study of low mass embedded star clusters in reflection nebulae

    NASA Astrophysics Data System (ADS)

    Soares, J. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2005-02-01

    An analysis of the candidate embedded stellar systems in the reflection nebulae vdBH-RN 26, vdBH-RN} 38, vdBH-RN} 53a, GGD 20, ESO 95-RN 18 and NGC 6595 is presented. Optical spectroscopic data from CASLEO (Argentina) in conjunction with near infrared photometry from the 2MASS Point Source Catalogue were employed. The analysis is based on source surface density, colour-colour and colour-magnitude diagrams together with theoretical pre-main sequence isochrones. We take into account the field population affecting the analysis by carrying out a statistical subtraction. The fundamental parameters for the stellar systems were derived. The resulting ages are in the range 1-4 Myr and the objects are dominated by pre-main sequence stars. The observed masses locked in the clusters are less than 25 M⊙. The studied systems have no stars of spectral types earlier than B, indicating that star clusters do not necessarily evolve through an HII region phase. The relatively small locked mass combined with the fact that they are not numerous in catalogues suggests that these low mass clusters are not important donors of stars to the field populations. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  7. Synthesis, spectroscopic characterization and electrochemical studies of Girard's T chromone complexes

    NASA Astrophysics Data System (ADS)

    Al-Saeedi, Sameerah I.; Alaghaz, Abdel-Nasser M. A.; Ammar, Reda A.

    2016-05-01

    Complexes of cobalt(II), nickel(II), copper(II) and zinc(II) of general composition [M(L)2] have been. The elemental analyses, molar conductance, spectral, magnetic moment and thermal measurements studies of the compounds led to the conclusion that the ligand acts as a tridentate manner (OON). The molar conductance of the metal complexes in fresh solution of DMSO lies in the range of 8.10-10.18 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of analytical and spectroscopic techniques, octahedral geometry of the complexes was proposed. The ligand field parameters were calculated for Co(II), Ni(II) and Cu(II) complexes and their values were found in the range reported for a octahedral structure. The data show that the complexes have composition of ML2 type. The activation of thermodynamic parameters are calculated using different equations. The octahedral geometry of the complexes is confirmed using DFT method from DMOL3 calculations and ligand field parameters. The cyclic voltammograms of the Cu(II)/Co(II)/Ni(II) complexes investigated in DMSO solution exhibit metal centered electroactivity in the potential range -1.5 to +1.5 V. The electrochemical data obtained for Cu(II) complexes explains the change of structural arrangement of the ligand around Cu(II) ions.

  8. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

    PubMed Central

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  9. Raman spectroscopic study of the Chromobacterium violaceum pigment violacein using multiwavelength excitation and DFT calculations.

    PubMed

    Jehlička, Jan; Edwards, Howell G M; Němec, Ivan; Oren, Aharon

    2015-01-01

    Violacein is a bisindole pigment occurring as a biosynthetic product of Chromobacterium violaceum and Janthinobacterium lividum. It has some structural similarities to the cyanobacterial UV-protective pigment scytonemin, which has been the subject of comprehensive spectroscopic and structural studies. A detailed experimental Raman spectroscopic study with visible and near-infrared excitation of violacein produced by C. violaceum has been undertaken and supported using theoretical DFT calculations. Raman spectra with 514 and 785 nm excitation of cultivated cells as well as extracts and Gaussian (B3LYP/6-311++G(d,p)) calculations with proposed molecular vibrational assignments are reported here.

  10. Task 1.11, Spectroscopic field screening of hazardous waste and toxic spills. Semi-annual report, July 1--December 31, 1995

    SciTech Connect

    1995-12-31

    The overall objective of this project is to study the feasibility of using and evanescent field absorbance sensor Fourier transform infrared (EFAS FT-IR) spectroscopic sensor coupled with cone penetrometry (CPT) as a field screening method. The specific objectives of this project are as follows: design an accessory for use with FT-IR that interfaces the spectrometer to a cone penetrometer; characterize the response of the FT-IR accessory to selected hydrocarbons in a laboratory-simulated field environment; and determine the ability of the FT-IR-CPT instrument to measure hydrocarbon contamination in soil by direct comparison with a reference method (e.g., Soxhlet extraction followed by gas chromatography) to quantify hydrocarbon from the same soil. Work performed during the second two quarters was focused on three areas: characterization of a candidate polymeric film for use in solid-phase microextraction (SPME) of analytes onto the sensor; evaluation of EFAS design; and development of a conceptual design for a spectroscopic sensor.

  11. Two spectroscopically confirmed galaxy structures at z = 0.61 and 0.74 in the CFHTLS Deep 3 field

    NASA Astrophysics Data System (ADS)

    Adami, C.; Cypriano, E. S.; Durret, F.; Le Brun, V.; Lima Neto, G. B.; Martinet, N.; Perez, F.; Rouze, B.; Sodré, L.

    2015-03-01

    Context. Galaxy evolution is known to depend on environment since it differs in clusters and in the field, but studies are sometimes limited to the relatively nearby Universe (z < 0.5). It is still necessary to increase our knowledge of cluster galaxy properties above z = 0.5. Aims: In a previous paper we have detected several cluster candidates at z> 0.5 as part of a systematic search for clusters in the Canada France Hawaii Telescope Legacy Survey by applying the Adami & MAzure Cluster FInder (AMACFI), based on photometric redshifts. We focus here on two of them, located in the Deep 3 (hereafter D3) field: D3-6 and D3-43. Methods: We have obtained spectroscopy with Gemini/GMOS instrument and measured redshifts for 23 and 14 galaxies in the two structures. These redshifts were combined with those available in the literature. A dynamical and a weak lensing analysis were also performed, together with the study of X-ray Chandra archive data. Results: Cluster D3-6 is found to be a single structure of eight spectroscopically confirmed members at an average redshift z = 0.607, with a velocity dispersion of 423 km s-1. It appears to be a relatively low-mass cluster. D3-43-S3 has 46 spectroscopically confirmed members at an average redshift z = 0.739. The cluster can be decomposed into two main substructures, having a velocity dispersion of about 600 and 350 km s-1. An explanation of the fact that D3-43-S3 is detected through weak lensing (only marginally, at the ~3σ level) but not in X-rays could be that the two substructures are just beginning to merge more or less along the line of sight. We also show that D3-6 and D3-43-S3 have similar global galaxy luminosity functions, stellar mass functions, and star formation rate (SFR) distributions. The only differences are that D3-6 exhibits a lack of faint early-type galaxies, a deficit of extremely high stellar mass galaxies compared to D3-43-S3, and an excess of very high SFR galaxies. Conclusions: This study shows the

  12. Electrochemical and spectroscopic study of octadecyltrimethylammonium bromide/DNA surfoplexes.

    PubMed

    Rodríguez-Pulido, Alberto; Aicart, Emilio; Junquera, Elena

    2009-04-21

    The use of cationic micelles consisting of octadecyltrimethylammonium bromide (C18TAB) to compact calf thymus DNA has been investigated in aqueous buffered solution at 310.15 K by means of conductometry, electrophoretic mobility, and several fluorescence spectroscopy methods. The results indicate that C18TAB micelles, consisting of 44 monomers on average, may compact DNA molecule by an electrostatic interaction that takes place at the cationic spherical micelle surface. The surfoplexes thus formed show a surface density charge that goes from negative to positive values at a Lmic/D mass ratio of around 1.0 (where Lmic and D are the masses of micellized cationic surfactant and DNA), called the isoneutrality ratio (Lmic/D)phi. Values of this characteristic parameter, determined in this work not only from the electrochemical experimental data but also from spectroscopic measurements, are in very good agreement with those ones calculated from molecular parameters and some other properties also obtained in this work. The electrostatic character of the DNA-micelle interaction has been confirmed by analyzing the decrease in fluorescence emission of the fluorophore ethidium bromide, EtBr, initially intercalated between DNA base pairs, as long as the surfoplexes are formed. Fluorescence anisotropy experiments have revealed that micelle packing becomes more rigid in the presence of DNA, but once the surfoplex is formed, the fluidity increases with the Lmic/D mass ratio, attaining its maximum when the isoneutrality ratio is exceeded. This fact, together with the net positive charge of the surfoplexes with the Lmic/D mass ratio over the isoneutrality ratio, makes this regimen of lipid and DNA content the optimum for efficiency in the transfection process.

  13. A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: Lens Environments and Line-of-Sight Structures

    NASA Astrophysics Data System (ADS)

    Wilson, Michelle; Zabludoff, Ann I.; Wong, Kenneth C.; Keeton, Charles R.; French, Katheryn Decker; Momcheva, Ivelina G.; Williams, Kurtis A.

    2016-01-01

    Galaxy-scale strong gravitational lensing has long been used to measure cosmological parameters such as the Hubble constant as well as the dark matter properties of galaxy halos. Additional mass around the lens galaxy or projected in the line-of-sight affects the light bending and needs to be incorporated into lensing analyses. We present new results from a spectroscopic survey to characterize the environmental and line-of-sight mass for 28 galaxy-scale lens fields. We show how the external convergence, number of lensed images, and lensed image separation are altered by groups at the lens and along the sightline.

  14. FTIR Spectroscopic Studies on Cross Linking of SU-8 Photoresist

    NASA Astrophysics Data System (ADS)

    Kalaiselvi, S. M. P.; Tan, T. L.; Rawat, R. S.; Lee, P.; Heussler, S. P.; Breese, M. B. H.

    2013-11-01

    The usage of chemically-amplified, negative tone SU-8 photoresist is numerous, spanning industrial, scientific and medical fields. Hence, in this study, some preliminary studies were conducted to understand the dosage and heat treatment requirements of the SU-8 photoresist essential for pattern generation using X-ray lithography. In this work, using Synchrotron as the X-ray source, SU-8 photoresist was characterized for X-ray lithography in terms of its process parameters such as X-ray exposure dose, post exposure bake (PEB) time and temperature for various photoresist thicknesses which is considered worthwhile in view of applications of SU-8 for the fabrication of very high aspect ratio micro structures. The process parameters were varied and the resultant cross linking of the molecular chains of the photoresist was accurately monitored using a Fourier Transform Infra-Red (FTIR) spectrometer and the results are discussed. The infrared absorption peak at 914 cm-1 in the spectrum of the SU-8 photoresist was found to be a useful indicator for the completion of cross linking in the SU-8 photoresist. Results show that the cross linking of the SU-8 photoresist is at a higher rate from 0 J/cm3 to 30 J/cm3 after which the peak almost saturates regardless of the PEB time. It is a good evidence for the validation of dosage requirement of SU-8 photoresist for effective completion of cross linking, which in turn is a requirement for efficient fabrication of micro and nano structures. An analogous behavior was also observed between the extent of cross linking and the PEB time and temperature. The rate of cross linking declines after a certain period of PEB time regardless of PEB temperature. The obtained results also show a definite relation between variation of the absorbance area of the peak at 914 cm-1 and the X-ray exposure dose.

  15. Spectroscopic investigation of fast (ns) magnetic field penetration in a plasma

    NASA Astrophysics Data System (ADS)

    Sarfaty, M.; Shpitalnik, R.; Arad, R.; Weingarten, A.; Krasik, Ya. E.; Fruchtman, A.; Maron, Y.

    1995-06-01

    The time-dependent magnetic field spatial distribution in a coaxial positive-polarity plasma opening switch (POS) carrying a current ≂135 kA during ≂100 ns, was investigated by two methods. In the first, ionic line emission was observed simultaneously for two polarizations to yield the Doppler and Zeeman contributions to the line profiles. In the second method, the axial velocity distribution of ions was determined, giving the magnetic field through the ion equation of motion. This method requires knowledge of the electron density, here obtained from the observed particle ionization times. To this end, a lower bound for the electron kinetic energy was determined using various line intensities and time-dependent collisional-radiative calculations. An important necessity for POS studies is the locality of all measurements in r, z, and θ. This was achieved by using laser evaporation to seed the plasma nonperturbingly with the species desired for the various measurements. The Zeeman splitting and the ion motion showed magnetic field penetration through the 3.5 cm long plasma at a velocity ≂108 cm/s. The current density was found to be relatively high at the load-side edge of the switch plasma. It is suggested that this may cause plasma acceleration into the vacuum section toward the load, which is supported by charge-collector measurements. The fast magnetic field penetration agrees with estimates based on the Hall-field mechanism.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  17. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

    PubMed

    Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

    2015-03-15

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

  18. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

    NASA Astrophysics Data System (ADS)

    Deborah, M.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

    2015-03-01

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (0 0 2) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

  19. Spectroscopic study of molecular structure, antioxidant activity and biological effects of metal hydroxyflavonol complexes

    NASA Astrophysics Data System (ADS)

    Samsonowicz, Mariola; Regulska, Ewa

    2017-02-01

    Flavonols with varied hydroxyl substitution can act as strong antioxidants. Thanks to their ability to chelate metals as well as to donate hydrogen atoms they have capacity to scavenge free radicals. Their metal complexes are often more active in comparison with free ligands. They exhibit interesting biological properties, e.g. anticancer, antiphlogistic and antibacterial. The relationship between molecular structure and their biological properties was intensively studied using spectroscopic methods (UV-Vis, IR, Raman, NMR, ESI-MS). The aim of this paper is review on spectroscopic analyses of molecular structure and biological activity of hydroxyflavonol metal complexes.

  20. Spectroscopic Signatures and Structural Motifs of Dopamine: a Computational Study

    NASA Astrophysics Data System (ADS)

    Srivastava, Santosh Kumar; Singh, Vipin Bahadur

    2016-06-01

    Dopamine (DA) is an essential neurotransmitter in the central nervous system and it plays integral role in numerous brain functions including behaviour, cognition, emotion, working memory and associated learning. In the present work the conformational landscapes of neutral and protonated dopamine have been investigated in the gas phase and in aqueous solution by MP2 and DFT (M06-2X, ωB97X-D, B3LYP and B3LYP-D3) methods. Twenty lowest energy structures of neutral DA were subjected to geometry optimization and the gauche conformer, GIa, was found to be the lowest gas phase structure at the each level of theory in agreement with the experimental rotational spectroscopy. All folded gauche conformers (GI) where lone electron pair of the NH2 group is directed towards the π system of the aromatic ring ( 'non up' ) are found more stable in the gas phase. While in aqueous solution, all those gauche conformers (GII) where lone electron pair of the NH2 group is directed opposite from the π system of the aromatic ring ('up' structures) are stabilized significantly.Nine lowest energy structures, protonated at the amino group, are optimized at the same MP2/aug-cc-pVDZ level of theory. In the most stable gauche structures, g-1 and g+1, mainly electrostatic cation - π interaction is further stabilized by significant dispersion forces as predicted by the substantial differences between the DFT and dispersion corrected DFT-D3 calculations. In aqueous environment the intra-molecular cation- π distance in g-1 and g+1 isomers, slightly increases compared to the gas phase and the magnitude of the cation- π interaction is reduced relative to the gas phase, because solvation of the cation decreases its interaction energy with the π face of aromatic system. The IR intensity of the bound N-H+ stretching mode provides characteristic 'IR spectroscopic signatures' which can reflect the strength of cation- π interaction energy. The CC2 lowest lying S1 ( 1ππ* ) excited state of neutral

  1. Near infrared photometric and optical spectroscopic study of 22 low mass star clusters embedded in nebulae

    NASA Astrophysics Data System (ADS)

    Soares, J. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2008-02-01

    Aims:Among the star clusters in the Galaxy, those embedded in nebulae represent the youngest group, which has only recently been explored. The analysis of a sample of 22 candidate embedded stellar systems in reflection nebulae and/or HII environments is presented. Methods: We employed optical spectroscopic observations of stars in the directions of the clusters carried out at CASLEO (Argentina) together with near infrared photometry from the 2MASS catalogue. Our analysis is based on source surface density, colour-colour diagrams and on theoretical pre-main sequence isochrones. We take into account the field star contamination by carrying out a statistical subtraction. Results: The studied objects have the characteristics of low mass systems. We derive their fundamental parameters. Most of the cluster ages are younger than 2 Myr. The studied embedded stellar systems in reflection nebulae and/or HII region complexes do not have stars of spectral types earlier than B. The total stellar masses locked in the clusters are in the range 20-220 M⊙. They are found to be gravitationally unstable and are expected to dissolve in a timescale of a few Myr. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  2. The Rio Tinto Mars analogue site: an extremophilic Raman spectroscopic study.

    PubMed

    Edwards, Howell G M; Vandenabeele, Peter; Jorge-Villar, Susana E; Carter, Elizabeth A; Perez, Fernando Rull; Hargreaves, Michael D

    2007-12-15

    The Rio Tinto site is recognised as a terrestrial Mars analogue because of the presence of jarosite and related sulfates which have recently been identified by the NASA Mars Exploration Rover "Opportunity" in the El Capitan region of Meridiani Planum on Mars. It has long been known that acidophilic microbial action is responsible for the deep blood-red colour of the water in Rio Tinto, where the pH varies from about 1.5 to 3.0 and the water is rich in iron and sulfur. Following recent Raman spectroscopic characterisation of the mineral phases of the Rio Tinto system, we report here a study of the biological components found in several specimens of deposited minerals and near the waterside that were collected during a GeoRaman VI Conference organized field trip in 2006. Key biosignatures were found for carotenoids, scytonemin and mycosporine-like amino acids, which are indicative of the biological colonisation of exposed mineral substrates; information from this study will be useful for targeting Martian sites using a miniaturized Raman instrument where the biosignatures of relict or extant life could remain in the geological record.

  3. Measurement of moisture content in photovoltaic panel encapsulants using spectroscopic optical coherence tomography: a feasibility study

    NASA Astrophysics Data System (ADS)

    Rashtchi, Shabnam; Ruiz, Pablo D.; Wildman, Ricky; Ashcroft, Ian

    2012-10-01

    EVA, a copolymer of ethylene and vinyl acetate, is a common encapsulant material used in silicon-based PV modules. It contributes to the structural integrity of the modules, provides electrical insulation and also acts as an environmental barrier. However, water can diffuse through EVA into the modules, leading to swelling and chemical degradation, which can impact interfacial bonds, leading to delamination and allowing more ingress to occur that can eventually end up in accelerated corrosion and device failure. Fourier Transform infrared spectroscopy (FTIR) and gravimetric techniques have been used to quantify water concentration and the diffusion coefficient in free standing EVA films. However, these techniques cannot be applied to measure water content in PV modules deployed in the field, as the encapsulant is usually between a glass front sheet and a back sheet made of glass or multilayered films. In this paper we study the feasibility of combining FTIR and spectroscopic optical coherence tomography (SOCT) to measure water concentration of the EVA layer inside the modules. SOCT provides depth resolved spectral information and thus has the potential of measuring water absorption at different layers in the PV module. These depth-resolved measurements are necessary to inform predictive models developed to study the structural integrity, stability and durability of PV modules. The fundamental principle of the technique is explained, the optimum spectral ranges are identified and the feasibility of a SOCT system is discussed based on light source and detector characteristics. Other strategies are also considered.

  4. Spectroscopic Study of ThCl+ by Two-Photon Ionization

    NASA Astrophysics Data System (ADS)

    Bartlett, Joshua; VanGundy, Robert A.; Heaven, Michael; Peterson, Kirk

    2016-06-01

    Despite the irreplaceable role experimental data plays for evaluating the performance of computational predictions, diatomic actinide species have not received much spectroscopic attention. As an early actinide element, thorium-containing species are ideal candidates for these types of studies. The electronic structure is expected to be relatively simple compared to later actinides, and therefore allows straightforward assessment of calculations. Here, we have studied ThCl+ for the first time via resonant two-photon ionization of jet-cooled ThCl produced by laser ablation of the metal reacted with dilute Cl2. Laser-induced Fluorescence (LIF) spectra have been recorded for the neutral molecule from 16000 - 23500 cm-1 in search of a suitable intermediate state for subsequent two-photon ionization experiments. Monochromator dispersion of the fluorescence has recovered the ground state vibration and anharmonic constants of ThCl. Resonant Two-Photon Ionization (R2PI) within a time-of-flight mass spectrometer was used to confirm ThCl production, and Pulsed Field Ionization Zero Kinetic Energy photoelectron spectroscopy (PFI-ZEKE) has been performed to identify the ionization energy as well as several of the low-lying states of the ThCl+ molecule. These constants have been predicted at the CASPT2 and CCSD(T) levels of theory, and a discussion of the calculations' performance will be presented alongside the recorded spectra.

  5. Synthesis, spectroscopic characterization, and determination of the solution association energy of the dimer [Co{N(SiMe3)2}2]2: magnetic studies of low-coordinate Co(II) silylamides [Co{N(SiMe3)2}2L] (L = PMe3, pyridine, and THF) and related species that reveal evidence of very large zero-field splittings.

    PubMed

    Bryan, Aimee M; Long, Gary J; Grandjean, Fernande; Power, Philip P

    2013-10-21

    The synthesis, magnetic, and spectroscopic characteristics of the synthetically useful dimeric cobalt(II) silylamide complex [Co{N(SiMe3)2}2]2 (1) and several of its Lewis base complexes have been investigated. Variable-temperature nuclear magnetic resonance (NMR) spectroscopy of 1 showed that it exists in a monomer-dimer equilibrium in benzene solution and has an association energy (ΔGreacn) of -0.30(20) kcal mol(-1) at 300 K. Magnetic data for the polycrystalline, red-brown [Co{N(SiMe3)2}2]2 (1) showed that it displays strong antiferromagnetic exchange coupling, expressed as -2JexS1S2, between the two S = (3)/2 cobalt(II) centers with a Jex value of -215(5) cm(-1), which is consistent with its bridged dimeric structure in the solid state. The electronic spectrum of 1 in solution is reported for the first time, and it is shown that earlier reports of the melting point, synthesis, electronic spectrum, and magnetic studies of the monomer "Co{N(SiMe3)2}2" are consistent with those of the bright green-colored tetrahydrofuran (THF) complex [Co{N(SiMe3)2}2(THF)] (4). Treatment of 1 with various Lewis bases yielded monomeric three-coordinated species-[Co{N(SiMe3)2}2(PMe3)] (2), and [Co{N(SiMe3)2}2(THF)] (4), as well as the previously reported [Co{N(SiMe3)2}2(py)] (3)-and the four-coordinated species [Co{N(SiMe3)2}2(py)2] (5) in good yields. The paramagnetic complexes 2-4 were characterized by electronic and (1)H NMR spectroscopy, and by X-ray crystallography in the case of 2 and 4. Magnetic studies of 2-5 and of the known three-coordinated cobalt(II) species [Na(12-crown-4)2][Co{N(SiMe3)2}3] (6) showed that they have considerably larger χMT products and, hence, magnetic moments, than the spin-only values of 1.875 emu K mol(-1) and 3.87 μB, which is indicative of a significant zero-field splitting and g-tensor anisotropy resulting from the pseudo-trigonal crystal field. A fit of χMT for 2-6 yields a large g-tensor anisotropy, large negative D-values (between -62 cm(-1

  6. Electromagnetic Field Penetration Studies

    NASA Technical Reports Server (NTRS)

    Deshpande, M.D.

    2000-01-01

    A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

  7. Galactic Soft X-ray Emission Revealed with Spectroscopic Study of Absorption and Emission Spectra

    NASA Astrophysics Data System (ADS)

    Yamasaki, Noriko Y.; Mitsuda, K.; Takei, Y.; Hagihara, T.; Yoshino, T.; Wang, Q. D.; Yao, Y.; McCammon, D.

    2010-03-01

    Spectroscopic study of Oxygen emission/absorption lines is a new tool to investigate the nature of the soft X-ray background. We investigated the emission spectra of 14 fields obtained by Suzaku, and detected OVII and OVIII lines separately. There is an almost isotropic OVII line emission with 2 LU intensity. As the attenuation length in the Galactic plane for that energy is short, that OVII emission should arise within 300 pc of our neighborhood. In comparison with the estimated emission measure for the local bubble, the most plausible origin of this component is the solar wind charge exchange with local interstellar materials. Another component presented from the correlation between the OVII and OVIII line intensity is a thermal emission with an apparent temperature of 0.2 keV with a field-to-field fluctuation of 10% in temperature, while the intensity varies about a factor of 4. By the combination analysis of the emission and the absorption spectra, we can investigate the density and the scale length of intervening plasma separately. We analyzed the Chanrdra grating spectra of LMC X-3 and PKS 2155-304, and emission spectra toward the line of sight by Suzaku. In both cases, the combined analysis showed that the hot plasma is not iso-thermal nor uniform. Assuming an exponential disk distribution, the thickness of the disk is as large as a few kpc. It suggests that there is a thick hot disk or hot halo surrounding our Galaxy, which is similar to X-ray hot haloes around several spiral galaxies.

  8. Spectroscopic identification of a redshift 1.55 supernova host galaxy from the Subaru Deep Field Supernova Survey

    NASA Astrophysics Data System (ADS)

    Frederiksen, Teddy F.; Graur, Or; Hjorth, Jens; Maoz, Dan; Poznanski, Dovi

    2014-03-01

    Context. The Subaru Deep Field (SDF) Supernova Survey discovered ten Type Ia supernovae (SNe Ia) in the redshift range 1.5 < z < 2.0, determined solely from photometric redshifts of the host galaxies. However, photometric redshifts might be biased, and the SN sample could be contaminated by active galactic nuclei (AGNs). Aims: We aim to obtain the first robust redshift measurement and classification of a z > 1.5 SDF SN Ia host galaxy candidate. Methods: We use the X-shooter (U-to-K-band) spectrograph on the Very Large Telescope to allow the detection of different emission lines in a wide spectral range. Results: We measure a spectroscopic redshift of 1.54563 ± 0.00027 of hSDF0705.25, consistent with its photometric redshift of 1.552 ± 0.018. From the strong emission-line spectrum we rule out AGN activity, thereby confirming the optical transient as a SN. The host galaxy follows the fundamental metallicity relation showing that the properties of this high-redshift SN Ia host galaxy is similar to other field galaxies. Conclusions: Spectroscopic confirmation of additional SDF SN hosts would be required to confirm the cosmic SN rate evolution measured in the SDF. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under program ID 089.A-0739.

  9. Spectroscopic studies of the molecular parentage of radical species in cometary comae

    NASA Astrophysics Data System (ADS)

    Lewis, Benjamin; Pierce, Donna; Cochran, Anita

    2015-11-01

    We have observed several comets using an integral-field unit spectrograph (the George and Cynthia Mitchell Spectrograph) on the 2.7m Harlan J. Smith telescope at McDonald Observatory. Full-coma spectroscopic images were obtained for various radical species (C2, C3, CH, CN, NH2). By constructing azimuthal average profiles from the full-coma spectroscopic images we can test Haser model parameters with our observations. The Haser model was used to determine production rates and possible parent lifetimes that would be consistent with the model. By iterating through a large range of possible parents lifetimes, we can see what range of values in which the Haser model is consistent with observations. Also, this type of analysis gives us perspective on how sensitive the model's fit quality is to changes in parent lifetimes. Here, we present the work completed to date, and we compare our results to other comet taxonomic surveys.

  10. Dissolution of tablet-in-tablet formulations studied with ATR-FTIR spectroscopic imaging.

    PubMed

    Wray, Patrick S; Clarke, Graham S; Kazarian, Sergei G

    2013-03-12

    This work uses ATR-FTIR spectroscopic imaging to study the dissolution of delayed release and pH resistant compressed coating pharmaceutical tablets. Tablets with an inner core and outer shell were constructed using a custom designed compaction cell. The core of the delayed release tablets consisted of hydroxypropyl methylcellulose (HPMC) and caffeine. The shell consisted of microcrystalline cellulose (MCC) and glucose. The core of the pH resistant formulations was an ibuprofen and PEG melt and the shell was constructed from HPMC and a basic buffer. UV/vis spectroscopy was used to monitor the lag-time of drug release and visible optical video imaging was used as a complementary imaging technique with a larger field of view. Two delayed release mechanisms were established. For tablets with soluble shell sections, lag-time was dependent upon rapid shell dissolution. For tablets with less soluble shells, the lag-time was controlled by the rate of dissolution medium ingress through the shell and the subsequent expansion of the wet HPMC core. The pH resistant formulations prevented crystallization of the ibuprofen in the core during dissolution despite an acidic dissolution medium. FTIR imaging produced important information about the physical and chemical processes occurring at the interface between tablet sections during dissolution.

  11. WIYN open cluster study. LX. Spectroscopic binary orbits in NGC 6819

    SciTech Connect

    Milliman, Katelyn E.; Mathieu, Robert D.; Gosnell, Natalie M.; Geller, Aaron M.; Meibom, Søren; Platais, Imants

    2014-08-01

    We present the current state of the WOCS radial-velocity (RV) survey for the rich open cluster NGC 6819 (2.5 Gyr) including 93 spectroscopic binary orbits with periods ranging from 1.5 to 8000 days. These results are the product of our ongoing RV survey of NGC 6819 using the Hydra Multi-Object Spectrograph on the WIYN 3.5 m telescope. We also include a detailed analysis of multiple prior sets of optical photometry for NGC 6819. Within a 1° field of view, our stellar sample includes the giant branch, the red clump, and blue straggler candidates, and extends to almost 2 mag below the main sequence (MS) turnoff. For each star observed in our survey we present all RV measurements, the average RV, and velocity variability information. Additionally, we discuss notable binaries from our sample, including eclipsing binaries (WOCS 23009, WOCS 24009, and WOCS 40007), stars noted in Kepler asteroseismology studies (WOCS 4008, WOCS 7009, and WOCS 8007), and potential descendants of past blue stragglers (WOCS 1006 and WOCS 6002). We find the incompleteness-corrected binary fraction for all MS binaries with periods less than 10{sup 4} days to be 22% ± 3% and a tidal circularization period of 6.2{sub −1.1}{sup +1.1} days for NGC 6819.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  13. Hunting the parent of the Orphan stream. II. The first high-resolution spectroscopic study

    SciTech Connect

    Casey, Andrew R.; Keller, Stefan C.; Da Costa, Gary; Maunder, Elizabeth; Frebel, Anna

    2014-03-20

    We present the first high-resolution spectroscopic study on the Orphan stream for five stream candidates, observed with the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Clay telescope. The targets were selected from the low-resolution catalog of Casey et al.: three high-probability members, one medium, and one low-probability stream candidate were observed. Our analysis indicates that the low- and medium-probability targets are metal-rich field stars. The remaining three high-probability targets range over ∼1 dex in metallicity, and are chemically distinct compared to the other two targets and all standard stars: low [α/Fe] abundance ratios are observed, and lower limits are ascertained for [Ba/Y], which sit well above the Milky Way trend. These chemical signatures demonstrate that the undiscovered parent system is unequivocally a dwarf spheroidal galaxy, consistent with dynamical constraints inferred from the stream width and arc. As such, we firmly exclude the proposed association between NGC 2419 and the Orphan stream. A wide range in metallicities adds to the similarities between the Orphan stream and Segue 1, although the low [α/Fe] abundance ratios in the Orphan stream are in tension with the high [α/Fe] values observed in Segue 1. Open questions remain before Segue 1 could possibly be claimed as the 'parent' of the Orphan stream. The parent system could well remain undiscovered in the southern sky.

  14. Baja California: Field Study

    ERIC Educational Resources Information Center

    Frey, John; Stewart, Jack

    1974-01-01

    Describes how to plan and execute an extended field trip which provides first hand observation of biological and cultural systems. Socialization of the participants was achieved through common planning and goal achievement. (BR)

  15. Complementary spectroscopic studies of materials of security interest

    NASA Astrophysics Data System (ADS)

    Burnett, Andrew; Fan, Wenhui; Upadhya, Prashanth; Cunningham, John; Edwards, Howell; Munshi, Tasnim; Hargreaves, Michael; Linfield, Edmund; Davies, Giles

    2006-09-01

    We demonstrate that, through coherent measurement of the transmitted terahertz frequency electric fields, broadband (0.3 - 8 THz) time-domain spectroscopy can be used to measure far-infrared vibrational modes of a range of drugs-of-abuse and high explosives that are of interest to the forensic and security services. Our results indicate that absorption features in these materials are highly sensitive to the structural and spatial arrangement of the molecules. Terahertz frequency spectra are also compared with high-resolution low-frequency Raman spectra to assist in understanding the low-frequency inter- and intra-molecular vibrational modes of the molecules.

  16. Vibrational spectroscopic studies to acquire a quality control method of Eucalyptus essential oils.

    PubMed

    Baranska, M; Schulz, H; Reitzenstein, S; Uhlemann, U; Strehle, M A; Krüger, H; Quilitzsch, R; Foley, W; Popp, J

    2005-08-05

    This article presents a novel and original approach to analyze in situ the main components of Eucalyptus oil by means of Raman spectroscopy. The obtained two-dimensional Raman maps demonstrate a unique possibility to study the essential oil distribution in the intact plant tissue. Additionally, Fourier Transform (FT)-Raman and attenuated total reflection (ATR)-IR spectra of essential oils isolated from several Eucalyptus species by hydrodistillation are presented. Density Functional Theory (DFT) calculations were performed in order to interpret the spectra of the essential oils of the Eucalyptus species. It is shown that the main components of the essential oils can be recognized by both vibrational spectroscopic techniques using the spectral information of the pure terpenoids. Spectroscopic analysis is based on the key bands of the individual volatile substances and therefore allows one to discriminate different essential oil profiles of several Eucalyptus species. It has been found that the presented spectroscopic data correlate very well with those obtained by gas chromatography (GC) analysis. All these investigations are helpful tools to generate a fast and easy method to control the quality of the essential oils with vibrational spectroscopic techniques in combination with DFT calculations.

  17. How specific Raman spectroscopic models are: a comparative study between different cancers

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Kumar, K. Kalyan; Chowdary, M. V. P.; Maheedhar, K.; Krishna, C. Murali

    2010-02-01

    Optical spectroscopic methods are being contemplated as adjunct/ alternative to existing 'Gold standard' of cancer diagnosis, histopathological examination. Several groups are actively pursuing diagnostic applications of Ramanspectroscopy in cancers. We have developed Raman spectroscopic models for diagnosis of breast, oral, stomach, colon and larynx cancers. So far, specificity and applicability of spectral- models has been limited to particular tissue origin. In this study we have evaluated explicitly of spectroscopic-models by analyzing spectra from already developed spectralmodels representing normal and malignant tissues of breast (46), cervix (52), colon (25), larynx (53), and oral (47). Spectral data was analyzed by Principal Component Analysis (PCA) using scores of factor, Mahalanobis distance and Spectral residuals as discriminating parameters. Multiparametric limit test approach was also explored. The preliminary unsupervised PCA of pooled data indicates that normal tissue types were always exclusive from their malignant counterparts. But when we consider tissue of different origin, large overlap among clusters was found. Supervised analysis by Mahalanobis distance and spectral residuals gave similar results. The 'limit test' approach where classification is based on match / mis-match of the given spectrum against all the available spectra has revealed that spectral models are very exclusive and specific. For example breast normal spectral model show matches only with breast normal spectra and mismatch to rest of the spectra. Same pattern was seen for most of spectral models. Therefore, results of the study indicate the exclusiveness and efficacy of Raman spectroscopic-models. Prospectively, these findings might open new application of Raman spectroscopic models in identifying a tumor as primary or metastatic.

  18. Photometric Variability and Spectroscopic Characterisation of White Dwarfs in Kepler 2 Fields

    NASA Astrophysics Data System (ADS)

    Braker, I. P.; Burleigh, M. R.; Goad, M. R.; Casewell, S. L.; Buckley, D.; Holberg, J. B.; Lawrie, K. A.; Barstow, M. A.

    2017-03-01

    It had long been thought that the majority of white dwarfs (WDs) are photometrically stable at the level of a least a few mmags with the exception of those WDs in the instability strip and some magnetic WDs. However long term (≍ tens of days), high photometric precision, observations of such stars had not previously been undertaken. The Kepler and Kepler 2 (K2) missions have provided an opportunity to photometrically monitor a large sample (≍1000 –1500) of WDs. Our analysis of isolated WDs in campaigns 1 to 7 shows that up to ≍25% of the sample is photometrically variable, with some WDs with peak to peak amplitudes of >5%. Many of these targets had only been previously classified photometrically. Our spectroscopic follow up indicates that up to 20% may not be bona fide WDs.

  19. Highly Accurate Quartic Force Fields, Vibrational Frequencies, and Spectroscopic Constants for Cyclic and Linear C3H3(+)

    NASA Technical Reports Server (NTRS)

    Huang, Xinchuan; Taylor, Peter R.; Lee, Timothy J.

    2011-01-01

    High levels of theory have been used to compute quartic force fields (QFFs) for the cyclic and linear forms of the C H + molecular cation, referred to as c-C H + and I-C H +. Specifically the 33 3333 singles and doubles coupled-cluster method that includes a perturbational estimate of connected triple excitations, CCSD(T), has been used in conjunction with extrapolation to the one-particle basis set limit and corrections for scalar relativity and core correlation have been included. The QFFs have been used to compute highly accurate fundamental vibrational frequencies and other spectroscopic constants using both vibrational 2nd-order perturbation theory and variational methods to solve the nuclear Schroedinger equation. Agreement between our best computed fundamental vibrational frequencies and recent infrared photodissociation experiments is reasonable for most bands, but there are a few exceptions. Possible sources for the discrepancies are discussed. We determine the energy difference between the cyclic and linear forms of C H +, 33 obtaining 27.9 kcal/mol at 0 K, which should be the most reliable available. It is expected that the fundamental vibrational frequencies and spectroscopic constants presented here for c-C H + 33 and I-C H + are the most reliable available for the free gas-phase species and it is hoped that 33 these will be useful in the assignment of future high-resolution laboratory experiments or astronomical observations.

  20. In vivo localized proton spectroscopic studies of human gastrocnemius muscle

    SciTech Connect

    Narayana, P.A.; Jackson, E.F.; Hazle, J.D.; Fotedar, L.K.; Kulkarni, M.V.; Flamig, D.P.

    1988-10-01

    In vivo proton magnetic resonance spectroscopy studies of gastrocnemius muscle were performed in six normal volunteers. Both spatially resolved spectroscopy (SPARS) and stimulated echo acquisition mode (STEAM) sequences were used for volume localization. A number of water suppression sequences have been combined with these localization schemes. Among the various techniques investigated in these studies, STEAM with an inversion pulse (T1-discriminated spectrum) seems to have the best potential for in vivo localized high-resolution proton spectroscopy studies of human muscle.

  1. Optimization and spectroscopic studies on carbon nanotubes/PVA nanocomposites

    NASA Astrophysics Data System (ADS)

    Alghunaim, Naziha Suliman

    Nanocomposite films of polyvinyl alcohol (PVA) containing constant ratio of both single and multi-wall carbon nanotubes had been obtained by dispersion techniques and were investigated by different techniques. The infrared spectrum confirmed that SWNTs and MWNTs have been covalently related OH and Csbnd C bonds within PVA. The X-ray diffraction indicated lower crystallinity after the addition of carbon nanotubes (CNTs) due to interaction between CNTs and PVA. Transmission electron microscope (TEM) illustrated that SWNTs and MWNTs have been dispersed into PVA polymeric matrix and it wrapped with PVA. The properties of PVA were enhanced by the presence of CNTs. TEM images show uniform distribution of CNTs within PVA and a few broken revealing that CNTs broke aside as opposed to being pulled out from fracture surface which suggests an interfacial bonding between CNTs and PVA. Maximum value of AC conductivity was recorded at higher frequencies. The behavior of both dielectric constant (ɛ‧) and dielectric loss (ɛ″) were decreased when frequency increased related to dipole direction within PVA films to orient toward the applied field. At higher frequencies, the decreasing trend seems nearly stable as compared with lower frequencies related to difficulty of dipole rotation.

  2. Near-infrared spectroscopic studies of self-forming lipids and nanovesicles

    NASA Astrophysics Data System (ADS)

    Bista, Rajan K.; Bruch, Reinhard F.

    2009-02-01

    Lipids and liposomes have remained an active research topic for several decades due to their significance as membrane model. Several vibrational spectroscopic techniques have been developed and employed to study the properties of lipids and liposomes. In this study, near-infrared (NIR) spectroscopy has been used to analyze a suite of synthesized PEGylated lipids trademarked as QuSomesTM. The three amphiphiles used in this study, differ in their apolar hydrophobic chain length and contain various units of polar polyethylene glycol (PEG) head groups. In contrast to conventional phospholipids, this new kind of lipids forms liposomes spontaneously upon hydration, without the supply of external activation energy. Whilst the NIR spectra of QuSomesTM show a common pattern, differences in the spectra are observed which enable the lipids to be distinguished. NIR absorption spectra of these new artificial lipids have been recorded in the spectral range of 4800-9000 cm-1 (~2100-1100 nm) by using a new miniaturized spectrometer based on micro-optical-electro-mechanical systems (MOEMS) technology. In particular, we have established specific band structures as "molecular fingerprints" corresponding to overtones and combinations vibrational modes involving mainly C-H and O-H functional groups for sample analysis of QuSomesTM. Moreover, we have demonstrated that the nanovesicles formed by such lipids in polar solvents show high stability and obey Beer's law at low concentration. The results reported in this study may find applications in various field including the development of lipids based drug delivery systems.

  3. SPECTROSCOPIC STUDIES OF MATERIALS FOR ELECTROCHEMICAL ENERGY STORAGE

    SciTech Connect

    Greenbaum, Steven G.

    2014-03-01

    Several battery materials research projects were undertaken, suing NMR spectroscopy as a primary analytical tool. These include transport proerties of liquid and solid electrolytes and structural studies of Li ion electrodes.

  4. SPECTROSCOPIC STUDY OF SORPTION OF NITROGEN HETEROCYCLIC COMPOUNDS ON PHYLLOSILICATES

    EPA Science Inventory

    The present study focused on understanding the sorption characteristics of acridine (AcN)and acridine-9-carboxylic acid (AcNCOOH), two typical nitrogen heterocyclic compounds (NHCs), on well-characterized phyllosilicates (hectorite, saponite, and muscovite). Results presented in...

  5. Spectroscopic and theoretical study on alkali metal phenylacetates

    NASA Astrophysics Data System (ADS)

    Regulska, E.; Świsłocka, R.; Samsonowicz, M.; Lewandowski, W.

    2013-07-01

    The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of phenylacetic acid was studied. The FT-IR, FT-Raman and 1H and 13C NMR spectra were recorded for studied compounds. Characteristic shifts in IR and NMR spectra along alkali metal phenylacetates were observed. Good correlations between the wavenumbers of the vibrational bands in the IR spectra of phenylacetates and some alkali metal parameters such as ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy were found. The density functional hybrid method B3LYP with 6-311++G** basis set was used to calculate optimized geometrical structures of studied compounds. Aromaticity indices, atomic charges, dipole moments and energies were calculated as well as the wavenumbers and intensities of IR spectra and chemical shifts in NMR spectra. The theoretical parameters were compared to experimental characteristic of alkali metal phenylacetates.

  6. Spectroscopic mapping of the white horse alunite deposit, Marysvale volcanic field, Utah: Evidence of a magmatic component

    USGS Publications Warehouse

    Rockwell, B.W.; Cunningham, C.G.; Breit, G.N.; Rye, R.O.

    2006-01-01

    Previous studies have demonstrated that the replacement alunite deposits just north of the town of Marysvale, Utah, USA, were formed primarily by low-temperature (100??-170?? C), steam-heated processes near the early Miocene paleoground surface, immediately above convecting hydrothermal plumes. Pyrite-bearing propylitically altered rocks occur mainly beneath the steam-heated alunite and represent the sulfidized feeder zone of the H2S-dominated hydrothermal fluids, the oxidation of which at higher levels led to the formation of the alunite. Maps of surface mineralogy at the White Horse deposit generated from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were used in conjunction with X-ray diffraction studies of field samples to test the accuracy and precision of AVIRIS-based mineral mapping of altered rocks and demonstrate the utility of spectroscopic mapping for ore deposit characterization. The mineral maps identified multiple core zones of alunite that grade laterally outward to kaolinite. Surrounding the core zones are dominantly propylitically altered rocks containing illite, montmorillonite, and chlorite, with minor pyrite, kaolinite, gypsum, and remnant potassium feldspar from the parent rhyodacitic ash-flow tuff. The AVIRIS mapping also identified fracture zones expressed by ridge-forming selvages of quartz + dickite + kaolinite that form a crude ring around the advanced argillic core zones. Laboratory analyses identified the aluminum phosphate-sulfate (APS) minerals woodhouseite and svanbergite in one sample from these dickite-bearing argillic selvages. Reflectance spectroscopy determined that the outer edges of the selvages contain more dickite than do the medial regions. The quartz + dickite ?? kaolinite ?? APS-mineral selvages demonstrate that fracture control of replacement processes is more prevalent away from the advanced argillic core zones. Although not exposed at the White Horse deposit, pyrophyllite ?? ordered illite was identified

  7. Spectroscopic and Raman excitation profile studies of 3-benzoylpyridine

    NASA Astrophysics Data System (ADS)

    Sett, Pinaky; Datta, Shirsendu; Chowdhury, Joydeep; Ghosh, Manash; Mallick, Prabal Kumar

    2017-03-01

    In the present work IR, UV absorption and Raman spectra including Raman excitation profiles and structure of 3-benzoyl pyridine have been investigated. Detailed studies on the vibrational and electronic properties of the molecule have been carried out. All these studies are aided with valuable quantum chemical calculations. The structural changes encountered on excitation to the low lying excited states have been investigated. Theoretical profiles determined by the sum-over-states method based on pertinent Franck-Condon and Herzberg-Teller terms have satisfactorily simulated the experimentally measured relative Raman intensities and these are also in compliance with the structural changes and potential energy distributions.

  8. Spectroscopic study for a chromium-adsorbed montmorillonite

    NASA Astrophysics Data System (ADS)

    Nurtay, Maidina ·; Tuersun, Maierdan ·; Cai, Yuanfeng; Açıkgöz, Muhammed; Wang, Hongtao; Pan, Yuguan; Zhang, Xiaoke; Ma, Xiaomei

    2017-02-01

    Samples of purified montmorillonite with trace amounts of quartz were subjected to different concentrations of chromium sulphate solutions for one week to allow cation exchange. The chromium-bearing montmorillonites were verified and tested using powder X-ray diffractometry (XRD), X-ray fluorescence spectrometry, electron spin resonance (ESR) spectrometry and Fourier transformation infrared (FTIR) spectroscopy to explore the occupation sites of the chromium. The ESR spectra recorded before and after the chromium exchange show clear differences: a strong and broad resonance with two shoulders at the lower magnetic field side was present to start, and its intensity as well as that of the ferric iron resonance, increased with the concentration of added chromium. The signals introduced by the chromium, for example at g = 1.975 and 2.510 etc., suggested that the chromium had several occupational sites. The ESR peak with g = 2.510 in the second derivative spectrum suggested that Cr3+ was weakly bounded to TOT with the form of [Cr(H2O)3]3+ in hexagonal cavities. This was verified by comparing the FTIR spectra of the pure and modified montmorillonite. The main resonance centred at g = 1.975 indicated that the majority of Cr3+ occupied the interlayer region as [Cr(H2O)6]3+. The substitution of Ca2 + by Cr3+ also greatly affected the vibration of the hydrogens associate to water, ranged from 3500 to 2600 cm-1 in FTIR. Furthermore, the presence of two diffraction lines in the XRD results (specifically those with d-values of 1.5171 and 1.2673 nm) and the calculations of the size of the interlayer space suggested the presence of two types of montmorillonite with different hydration cations in the sample exposed to 0.2 M chromium sulphate. The two diffraction lines were assigned to [Cr(H2O)6]3+ and [Cr(H2O)3O3]3+, respectively. This also suggested that the species of hydration cation was constrained by the concentration of the chromium solution.

  9. Spectroscopic Studies of Atomic and Molecular Processes in the Edge Region of Magnetically Confined Fusion Plasmas

    SciTech Connect

    Hey, J. D.; Brezinsek, S.; Mertens, Ph.; Unterberg, B.

    2006-12-01

    Edge plasma studies are of vital importance for understanding plasma-wall interactions in magnetically confined fusion devices. These interactions determine the transport of neutrals into the plasma, and the properties of the plasma discharge. This presentation deals with optical spectroscopic studies of the plasma boundary, and their role in elucidating the prevailing physical conditions. Recorded spectra are of four types: emission spectra of ions and atoms, produced by electron impact excitation and by charge-exchange recombination, atomic spectra arising from electron impact-induced molecular dissociation and ionisation, visible spectra of molecular hydrogen and its isotopic combinations, and laser-induced fluorescence (LIF) spectra. The atomic spectra are strongly influenced by the confining magnetic field (Zeeman and Paschen-Back effects), which produces characteristic features useful for species identification, temperature determination by Doppler broadening, and studies of chemical and physical sputtering. Detailed analysis of the Zeeman components in both optical and LIF spectra shows that atomic hydrogen is produced in various velocity classes, some related to the relevant molecular Franck-Condon energies. The latter reflect the dominant electron collision processes responsible for production of atoms from molecules. This assignment has been verified by gas-puffing experiments through special test limiters. The higher-energy flanks of hydrogen line profiles probably also show the influence of charge-exchange reactions with molecular ions accelerated in the plasma sheath ('scrape-off layer') separating limiter surfaces from the edge plasma, in analogy to acceleration in the cathode-fall region of gas discharges. While electron collisions play a vital role in generating the spectra, ion collisions with excited atomic radiators act through re-distribution of population among the atomic fine-structure sublevels, and momentum transfer to the atomic nuclei via

  10. Optical spectroscopic studies of heme proteins at high pressure

    SciTech Connect

    Swanson, B.I.; Agnew, S.F.; Ondrias, M.R.; Alden, R.G.

    1986-01-22

    There has been considerable interest in studying the physical and chemical behavior of small molecules at high static pressure by using diamond-anvil cells. In contrast to the relatively rich chemistry now developing on small molecules at high densities, studies of metalloproteins have largely been limited to relatively low pressures (<7 kbar) using UV-vis absorption, magnetic susceptibility, or NMR spectroscopy. Low-pressure studies of a variety of oxidized heme proteins have conclusively shown evidence for spin-state changes for the iron site at pressures above 1 kbar. Optical absorption studies of reduced heme proteins, while not conclusive, have also been interpreted in terms of spin-state changes. Other changes within the heme pocket most notably in the proximal histidine in the ..beta..-chain of Hb via proton NMR, have also been detected. The molecular bases for these changes and the behavior of the heme electronic states at higher pressures, however, remain open questions. In this paper both resonance Raman and absorption spectroscopy are used to address these problems in reduced heme proteins. Resonance Raman scattering is well suited for this application as it provides a structurally specific probe of the heme active site. 11 references, 2 figures.

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

    EPA Science Inventory

    Metal oxide phases play an important role in governing the sorption and desorption mechanisms of metals in water, soils, and sediments. Many researchers have examined the efficiency of Pb sorption on Mn, Fe, Al, Ti, and Si oxide surfaces. Most studies concluded that adsorption ...

  12. Magnetic resonance and optical spectroscopic studies of carotenoids

    SciTech Connect

    Kispert, L.D.

    1991-05-01

    It is our goal to study the role of a host lattice in the formation of radicals and excited singlet and triplet states that are relevant to photosynthesis. Particular emphasis is being placed on determining what is special about carotenoids that natural photosynthetic systems require them as antennae as well as for protection. We are thus manipulating the host matrix so as to understand the carotenoid function (protection, quenching, energy transfer and antenna) and the structure of carotenoid cations. To characterize their properties, we have carried out EPR, ENDOR, optical, molecular orbital and electrochemical studies of carotenoids and carotenoid cations produced chemically, electrochemically, radiolytically (x-ray irradiated freon matrices) and photolytically (solution photolysis by excimer radiation) as a function of the host matrix. 36 refs.

  13. Green-synthesis, characterization, photostability and polarity studies of novel Schiff base dyes using spectroscopic methods.

    PubMed

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

    2012-01-01

    Preparation, characterization, photostability and polarity studies of novel Schiff base dyes using spectroscopic methods were achieved. The Schiff base dyes were prepared by the reaction of salicylaldehyde/2-Hydroxy-1-naphthaldehyde with aminophenazone under microwave irradiation. The spectroscopic (FT-IR, 1H NMR, 13C-NMR, Mass) studies and elemental analyses were in good agreement with chemical structure of synthesized compounds. In addition, UV-Vis and fluorescence spectroscopic experiments showed that these dyes are good absorbent and fluorescent. Based on the photostability study of these dyes, minimal to no loss in fluorescence intensities of 4-[(2-Hydroxy-benzylidene)-amino] 1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (D1) (6.14%) and 4-[(2-Hydroxy-naphthalen-1-ylmethylene)-amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (D2) (2.95%) was observed with an increase in the exposure time using time-based fluorescence steady-state experiments. These studies also inferred that these Schiffbase dyes have a high photostability against photobleaching. In addition, Dye 2 is found to be more sensitive than Dye 1 to the polarity of the microenvironment provided by different solvents based on the results of fluorescence polarity studies.

  14. Spectroscopic and computational study of a new isomer of salinomycin

    NASA Astrophysics Data System (ADS)

    Pankiewicz, Radosław

    2013-09-01

    A new derivative of polyether ionophore salinomycin was obtained as a result of a rearrangement catalysed by sulphuric acid in two-phase medium of water/methylene chloride solution. The new isomer was fully characterized by multinuclear 2D NMR, NOESY and MALDI-TOF. The properties of the new compound were additionally study by semiempirical (PM5) and DFT (B3LYP) methods. A potential mechanism of the rearrangement was also proposed.

  15. Spectroscopic Studies of Metal-Ligand-Surface Interactions

    DTIC Science & Technology

    1988-10-01

    recent calculations by Bauschlicher. In this theoretical study the complexes’ bonding was attributed to an electrostatic interaction between the...section about the bonding mechanisms in the ammonia versus the hydrazine complexes. 3. Normal Coordinate Calculations on Metal.Ammonia Complexes To...and Benzene ...... o......46 III CALCULATIONS OF THE VIBRATIONAL SPECTRA OF N2 H4 ,’ ALL ITS DEUTERATED DERIVATIVES AND CH3 N2 13 . ........ oo.o

  16. Spectroscopic studies of model polar stratospheric cloud films

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Koehler, Birgit G.; Middlebrook, Ann M.

    1993-01-01

    Fourier transform infrared (FTIR) spectroscopy has been used to study nitric-acid/ice films representative of type I polar stratospheric clouds (PSCs). These studies reveal that in addition to amorphous nitric acid/ice mixtures, there are three stable stoichiometric hydrates of nitric acid: nitric-acid monohydrate (NAM), dihydrate (NAD), and trihydrate (NAT). We also observe two distinct crystalline forms of the trihydrate, which we denote alpha- and beta-NAT. These two forms appear to differ in their concentration of crystalline defects, but not in their chemical composition. In addition to probing the composition of type I PSCs, we have also used FTIR spectroscopy to study the interaction of HCl with model PSC films. In this work we find that for HCl pressures in the range 10 exp -5 to 10 exp -7 Torr, HCl is taken up by ice at 155 K to form a thin layer of HCl.6H2O. At 193 K, the uptake of HCl by ice was consistent with less than or equal to monolayer coverage. Uptake of HCl by alpha and beta-NAT at 175 K was also consistent with less than or equal to monolayer coverage.

  17. SPECTROSCOPIC STUDIES OF STRUCTURE, DYNAMICS AND REACTIVITY IN IONIC LIQUIDS.

    SciTech Connect

    WISHART,J.F.

    2007-11-30

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate

  18. Mössbauer spectroscopic study of iron-chelate trammels

    NASA Astrophysics Data System (ADS)

    Pal, Sangita; Meena, S. S.; Ningthoujam, R. S.; Goswami, D.

    2014-04-01

    Any kind of waste effluent in the Indian context and other countries contains a lot of iron in any ore. During mining, milling, extraction and purification process iron acts as contaminant towards other metal's purity. It is essential to remove iron to the maximum extent. In this case, an "IN-HOUSE" resin polyacrylamidehydroxamic acid (PHOA) has been designed and developed which is highly hydrophilic three dimensionally cross-linked. It has an excellent iron binding capacity with almost no leaching. Interaction of resin with ammonium ferrous sulphate and red-mod (Fe2O3) is studied using Mössbauer spectroscopy.

  19. Electrochemical and spectroscopic studies of fuel cell reactions

    NASA Astrophysics Data System (ADS)

    Shao, Minhua

    Fuel cells, especially proton exchange membrane fuel cells (PEMFCs) are expected soon to become a major source of clean energy. However, the sluggish kinetics of the fuel cell reactions, i.e., the fuel oxidation and oxygen reduction, hinders the wide-spread application of PEMFCs. These problems prompted our studies to focus on elucidating the nature of the reaction intermediates during the oxidation of fuels and the reduction of oxygen on electrocatalysts, and understanding the mechanisms of these reactions. The results from these studies will provide basic information for designing new electrocatalysts. In this dissertation, the oxidation reactions of ethanol and dimethyl ether (DME) on Pt were investigated by the surface enhanced infrared absorption spectroscopy with an attenuated total reflection configuration (ATR-SEIRAS). Various reaction intermediates were detected and their electrochemical behaviors were studied. We also benefited from advantages of the ATR-SEIRAS technique and observed superoxide anion (O2-) and hydrogen peroxide anion (H2-) as the intermediates in the oxygen reduction reaction (ORR) on Pt and Au electrodes for the first time. The other main goal of this study is design of new electrocatalysts for ORR with low cost and high activity. Two novel electrocatalysts were developed. One is Pt monolayer electrocatalysts consisting of a Pt monolayer formed by a red-ox replacement of the Cu monolayer by Pt atoms on non-noble metal-noble metal core-shell nanoparticles. In such catalyst, the total noble mass activity of the catalyst was 2--6 times larger that of commercial Pt catalyst. Another way of lowering the cost of catalysts and enhancing the ORR activity involves alloying less expensive noble metals with other non-noble elements. In this dissertation, the nano-structured Pd based alloy electrocatalysts have been explored. The results showed that their ORR activities surpass that of commercial Pt. The density functional theory (DFT) calculations

  20. Raman and infrared spectroscopic study of turquoise minerals.

    PubMed

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L

    2015-10-05

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)(2-) units were observed.

  1. Raman and infrared spectroscopic study of turquoise minerals

    NASA Astrophysics Data System (ADS)

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L.

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)2- units were observed.

  2. 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.

  3. [Infrared spectroscopic study on leaf senescence of evergreen tree].

    PubMed

    Li, Lun; Zhou, Xiang-Ping; Liu, Gang; Zhang, Li; Ou, Quan-Hong; Hao, Jian-Ming

    2013-02-01

    In order to investigate plant physiological process of leaf senescence and aging, Fourier transform infrared (FTIR) spectroscopy was used to study the young, mature, and old yellow leaves from seven species of evergreen trees. The spectra of the leaves from different growing period are different in the region of 1 800-700 cm(-1). The absorption ratios A1 070/A2 927, A1 070/A1 160 were used to evaluate the relative changes of polysaccharides, and A1 318/A2 922 was used to estimate the change of calcium oxalate during leaf senescence. Decomposition and curve-fitting analysis was performed in the region of 1 800 -1 500 cm(-1). The sub-band absorption ratio H1 650/H1 740 was used to evaluate the relative changes of protein in the leaves. The results show that the accumulation and mobilization of polysaccharides, protein, and calcium oxalate during leaf growing period were different in different plant species. This study demonstrates the potential of mid-infrared spectroscopy for investigation of plants senescence, as well as physiological and biochemical changes of plants.

  4. Vibrational spectroscopic studies of Isoleucine by quantum chemical calculations.

    PubMed

    Moorthi, P P; Gunasekaran, S; Ramkumaar, G R

    2014-04-24

    In this work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of Isoleucine (2-Amino-3-methylpentanoic acid). The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments, thermodynamics properties, NBO analyses, NMR chemical shifts and ultraviolet-visible spectral interpretation of Isoleucine have been studied by performing MP2 and DFT/cc-pVDZ level of theory. The FTIR, FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1) respectively. The UV-visible absorption spectra of the compound were recorded in the range of 200-800 nm. Computational calculations at MP2 and B3LYP level with basis set of cc-pVDZ is employed in complete assignments of Isoleucine molecule on the basis of the potential energy distribution (PED) of the vibrational modes, calculated using VEDA-4 program. The calculated wavenumbers are compared with the experimental values. The difference between the observed and calculated wavenumber values of most of the fundamentals is very small. (13)C and (1)H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method and compared with experimental results. The formation of hydrogen bond was investigated in terms of the charge density by the NBO calculations. Based on the UV spectra and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. Besides, molecular electrostatic potential (MEP) were investigated using theoretical calculations.

  5. Ligand exchange in quaternary alloyed nanocrystals--a spectroscopic study.

    PubMed

    Gabka, Grzegorz; Bujak, Piotr; Giedyk, Kamila; Kotwica, Kamil; Ostrowski, Andrzej; Malinowska, Karolina; Lisowski, Wojciech; Sobczak, Janusz W; Pron, Adam

    2014-11-14

    Exchange of initial, predominantly stearate ligands for pyridine in the first step and butylamine (BA) or 11-mercaptoundecanoic acid (MUA) in the second one was studied for alloyed quaternary Cu-In-Zn-S nanocrystals. The NMR results enabled us to demonstrate, for the first time, direct binding of the pyridine labile ligand to the nanocrystal surface as evidenced by paramagnetic shifts of the three signals attributed to its protons to 7.58, 7.95 and 8.75 ppm. XPS investigations indicated, in turn, a significant change in the composition of the nanocrystal surface upon the exchange of initial ligands for pyridine, which being enriched in indium in the 'as prepared' form became enriched in zinc after pyridine binding. This finding indicated that the first step of ligand exchange had to involve the removal of the surface layer enriched in indium with simultaneous exposure of a new, zinc-enriched layer. In the second ligand exchange step (replacement of pyridine with BA or MUA) the changes in the nanocrystal surface compositions were much less significant. The presence of zinc in the nanocrystal surface layer turned out necessary for effective binding of pyridine as shown by a comparative study of ligand exchange in Cu-In-Zn-S, Ag-In-Zn-S and CuInS2, carried out by complementary XPS and NMR investigations.

  6. Multinuclear nuclear magnetic resonance spectroscopic study of cartilage proteoglycans

    SciTech Connect

    Lerner, L.

    1985-01-01

    Hyaline cartilage is a composite material whose major function is to withstand compression while retaining flexibility. Its mechanical properties are affected by tissue hydration and ionic composition. Models of the mechanical behavior of cartilage have incorporated certain assumptions about the interactions of the major components of cartilage: collagen, proteoglycans, water, and cations. To determine the validity of these assumption, the authors have used nuclear magnetic resonance spectroscopy (NMR). Two approaches have been used: (a) natural abundance carbon-13 NMR; and (b) NMR of sodium-23, potassium-39, magnesium-25, and calcium-43. Evidence from studies in intact tissues are reinforced by extensive measurements on solutions of proteoglycans and other relevant macromolecules. Based on the measurements of NMR relaxation rates and lineshapes reported here, it is concluded that neither sodium nor potassium interact strongly with bovine nasal proteoglycan aggregates or their substituent glycosaminoglycan chains in solution. Proteoglycans do bind magnesium and calcium. Therefore there is a qualitative difference between monovalent and divalent cations, which is not taken into account by polyelectrolyte models or models for the ionic dependence of mechanical properties. Cation binding to heparin, which has a higher charge density than cartilage proteoglycans, was also studied. The results presented here establish that heparin binds sodium, magnesium, and calcium.

  7. Raman spectroscopic study of Lactarius spores (Russulales, Fungi)

    NASA Astrophysics Data System (ADS)

    De Gussem, Kris; Vandenabeele, Peter; Verbeken, Annemieke; Moens, Luc

    2005-10-01

    Fungi are important organisms in ecosystems, in industrial and pharmaceutical production and are valuable food sources as well. Classical identification is often time-consuming and specialistic. In this study, Raman spectroscopy is applied to the analysis of fungal spores of Lactarius, an economically and ecologically important genus of Basidiomycota. Raman spectra of spores of Lactarius controversus Pers.: Fr., Lactarius lacunarum (Romagn.) ex Hora, Lactarius quieticolor Romagn. and Lactarius quietus (Fr.: Fr.) Fr. are reported for the first time. The spectra of these species show large similarity. These spectra are studied and compared with the Raman spectra of reference substances known to occur in macrofungi, including saccharides, lipids and some minor compounds that may serve as specific biomarkers (adenine, ergosterol and glycine). Most Raman bands could be attributed to specific components. In agreement with the biological role of fungal spores, high amounts of lipids were observed, the main fatty acid being oleate. In addition to different types of lipids and phospholipids, the polysaccharides chitin and amylopectin could be detected as well. The presence of trehalose is not equivocally shown, due to overlapping bands. Raman band positions are reported for the observed bands of the different species and reference products.

  8. Vibrational spectroscopic studies of adsorbates on bimetallic surfaces. Doctoral thesis

    SciTech Connect

    Kuhn, W.K.

    1992-12-01

    In this work, well-defined bimetallic surfaces have been studied using carbon monoxide adsorption in conjunction with infrared reflection absorption spectroscopy (IRAS). These studies have indicated that for CO adsorbed on Cu overlayers, the bond between the CO and the Cu adatoms is comprised of both pi-back-donation and polarization interaction components. The sum of the contributions from these effects determines the observed bond strength with the observed CO stretching frequency being determined by the relative contributions of the components. In addition, it was determined that IR spectra of adsorbed CO show a remarkable sensitivity to surface structure. Three-dimensional Cu clusters, well-ordered two dimensional Cu islands and isolated Cu atoms are distinctively characterized by their CO IR peaks. In addition, both disorder-order and order-order transitions are observed for the metal overlayers on the single crystal metal substrates. It was also observed that localized segregation and ordering of mixed Co and S overlayers on a Mo(110) substrate occurs upon annealing.

  9. Theoretical spectroscopic study of protonated and deuteronated PAHs

    NASA Astrophysics Data System (ADS)

    Buragohain, Mridusmita; Pathak, Amit

    The study of Polycyclic Aromatic Hydrocarbon (PAH) plays a key role to understand astrophysical environments as they are ubiquitous in the Interstellar Medium (ISM). They account for about 5-10% of carbon budget in the universe and are responsible for the strong IR emission features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7mum seen towards most of the interstellar objects including HII regions, reflection nebulae, planetary nebulae, late-type stars, as well as active star-forming regions. These IR features result from the relaxation of vibrationally excited PAHs. As PAHs are stable enough to survive the interstellar conditions, they could possibly be responsible for the enigmatic Diffuse Interstellar Bands (DIBs) which are optical absorption features on the interstellar extinction curve. The fact that interstellar PAHs are more likely to be ions has motivated the study of radical PAHs. Protonated PAHs formed by H(+) addition to neutral parent molecules, denoted as HPAH(+) , are an important form of closed shell PAH cation. Protonated forms show electronic transitions in the visible part of the spectrum where most DIBs are present, whereas neutral forms generally show their strongest electronic transitions in the UV region. We also report quantum chemical calculations on HPAH(+) and DPAH(+) (D(+) attached to PAH) to get the electronic and IR spectra to understand the IR emission and DIB features. A comparison of theoretical spectra with the available experimental spectra has also been carried out.

  10. Kinetic and Spectroscopic Studies of Heterogeneous Catalytic Reactions

    NASA Astrophysics Data System (ADS)

    Wilke, Todd E.

    1990-01-01

    The selective oxidation of ethylene was studied on a high surface area colloidal silver catalyst. In 0.1 to 1 torr of 20% ethylene in oxygen, the catalyst produced ethylene oxide with a selectivity of 20 to 30% at temperatures between 473 and 573 K. Surface-enhanced Raman (SER) spectra exhibited a distinct feature at 995 cm^ {-1}. This band was also observed for catalysts exposed to just oxygen, and it shifted to 980 cm^{-1} after heating the catalyst to 873 K in ^{18} O_2. No isotopic shift was observed with ^{18}O _2 at temperatures below 573 K. Similar spectral results were obtained at atmospheric pressure. For silver catalysts that contain adsorbed chlorine, SER bands were observed at 240, 1015, and 1045 cm^ {-1} in oxygen-containing atmospheres; the 995 cm^{-1} band was not evident. The extension of SERS to other metals that do not exhibit the surface-enhanced effect was examined by electrodepositing thin layers (2 to 3 monolayers) of platinum, rhodium, and ruthenium on a roughened gold substrate. At atmospheric pressure and temperatures between 298 and 473 K, metal-oxygen features were observed at 500 cm ^{-1}, and 490 and 600 cm ^{-1} in SER spectra of rhodium and ruthenium surfaces exposed to oxygen, respectively. Bands attributed to adsorbed carbon monoxide were observed in SER spectra of platinum (470, 2060, 390, and 1890 cm ^{-1}) and rhodium (465 and 2040 cm^{-1}) surfaces exposed to carbon monoxide and oxygen mixtures. The temporal replacement of adsorbed carbon monoxide by nitric oxide as well as temperature-induced changes in the surface composition were studied on a seconds timescale with a spectrograph -charge coupled device detector arrangement. The adsorption and oxidation of sulfur dioxide was also studied. A band assigned to the S-O stretch of molecularly adsorbed sulfur dioxide was observed at 1130 cm^{-1} on unmodified gold and platinum-coated gold surfaces exposed to sulfur dioxide at 298 K. Dissociative chemisorption of sulfur dioxide on

  11. Negative ion photoelectron spectroscopic studies of transition metal cluster

    NASA Astrophysics Data System (ADS)

    Marcy, Timothy Paul

    The studies reported in this thesis were performed using a negative ion photoelectron spectrometer consisting of a cold cathode DC discharge ion source, a flowing afterglow ion-molecule reactor, a magnetic sector mass analyzer, an argon ion laser for photodetachment and a hemispherical electron kinetic energy analyzer and microchannel plate detector for photoelectron spectrum generation. The 476.5 nm (2.601 eV), 488.0 nm (2.540 eV) and 514.5 nm (2.410 eV) negative ion photoelectron spectra of VMn are reported and compared to the previously studied spectra of isoelectronic Cr2.1 The photoelectron spectra are remarkably similar to those of Cr2 in electron affinity and vibrational frequencies. The 488.0 nm photoelectron spectra and electron affinities of Nb n- (n = 1 - 9) are reported with discussion of observed vibrational structure. There are transitions to several electronic states of Nb2 in the reported spectra with overlapping vibrational progressions. The spectra of Nb3, Nb4 and Nb6 show partially resolved vibrational structure in the transitions to the lowest observed electronic state of each cluster. There is a single distinct active vibrational mode in the transition to the ground state of Nb8. Spin-orbit energies of Nb- are also reported. The 488.0 nm negative ion photoelectron spectra of Nb3H(D) are reported and compared to those of Nb3. There is a single vibrational mode active in the spectra of Nb3H(D) which is very similar to the most distinct mode active in the spectrum of Nb3. The 488.0 nm photoelectron spectra of the NbxCyH(D) y- (x = 1, 2, 3, y = 2, 4, 6) dehydrogenated products of the reactions of ethylene with niobium cluster anions are reported. Temperature studies of some of these species give evidence for the presence of multiple isomers of each molecule in the ion beam. The spectra of NbC6H(D) 6 are identical to those obtained from the reactions of benzene with niobium clusters and indicate that benzene is being formed from ethylene in the flow

  12. Spectroscopic Results from the Life in the Atacama (LITA) Project 2004 Field Season

    NASA Technical Reports Server (NTRS)

    Piatek, J. L.; Moersch, J. E.; Wyatt, M.; Rampey, M.; Cabrol, N. A.; Wettergreen, D. S.; Whittaker, R.; Grin, E. A.; Diaz, G. Chong

    2005-01-01

    Introduction: The Life in the Atacama (LITA) project includes rover field tests designed to look for life in the arid environment of the Atacama Desert (Chile). Field instruments were chosen to help remote observers identify potential habitats and the presence of life in these habitats, and included two spectrometers for help in identifying the mineralogy of the field sites. Two field trials were undertaken during the 2004 field season. The remote science team had no prior knowledge of the local geology, and relied entirely on orbital images and rover-acquired data to make interpretations. Each field trial lasted approximately one week: the sites for these trials were in different locations, and are designated "Site B" and "Site C."

  13. Identification and derivatization of selected cathinones by spectroscopic studies.

    PubMed

    Nycz, Jacek E; Pazdziorek, Tadeusz; Malecki, Grzegorz; Szala, Marcin

    2016-09-01

    In this study we identified three novel hydrochloride salts of cathinones 2-(pyrrolidin-1-yl)-1-(5,6,7,8-tetrahydronaphthalen-2-yl)pentan-1-one (1a) (TH-PVP), 2-(methylamino)-1-(2-methylphenyl)-1-propanone (1b) (2-MMC) and 1-(4-chlorophenyl)-2-(methylamino)propan-1-one (1c) (4-CMC). Their properties have been examined through combinations of GC-MS, IR, NMR, electronic absorption spectroscopy and single crystal X-ray diffraction method. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, N-methyl and carbonyl groups. Additionally the use of thionation and amination reactions for identification of selected cathinones was presented.

  14. Spectroscopic Study of Sediments from Chapala Lake in Western Mexico

    NASA Astrophysics Data System (ADS)

    Arízaga, G. G. Carbajal; Doumer, M. E.; Lucio, G. Álvarez; Salazar, S. Gómez; Mangrich, A. S.; Huerta, A. García

    2016-11-01

    The first 10 cm of sediment from Lake Chapala, Western Mexico are in constant activity related to the exchange and speciation of metal cations. Samples of this sediment were analyzed in electron paramagnetic resonance (EPR) equipment to study the paramagnetic metals. Assays indicated that only Fe3+ was present in a detectable amount. This cation, along with chemical fractions of sediment obtained by sequential extraction, was analyzed by EPR. The analysis supported by infrared data revealed that Fe3+ was present in diluted and concentrated domains. Easily exchangeable iron was retained by carbonyl groups in organic matter. The carbonate fraction and oxides contained iron in concentrated domains. The alumina-silicate fraction (that resisted the sequential extraction digestions) presented diluted domains of iron in the octahedral alumina sheet along with occlusions of concentrated domains. This last inference was obtained by comparing EPR results against the spectrum of iron in synthetic model clay.

  15. 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.

  16. Preparations and spectroscopic studies of organotin complexes of diclofenac*1

    NASA Astrophysics Data System (ADS)

    Kourkoumelis, Nikolaos; Demertzis, Mavroudis A.; Kovala-Demertzi, Dimitra; Koutsodimou, Aglaia; Moukarika, Alice

    2004-08-01

    The reactions of the potent and widely used anti-inflammatory drug diclofenac, HL, with diorganotin(IV) oxides were studied. The dimeric tetraorganodistannoxane complexes [Me 2LSnOSnLMe 2] 2, [Bu 2LSnOSnLBu 2] 2, [Ph 2LSnOSnLPh 2] 2 and the dibutyltin complex [Bu 2SnL 2], have been prepared and structurally characterized in the solid state by means of vibrational and 119Sn Mössbauer spectroscopy. Determination of lattice dynamics by temperature-dependent 119Sn Mössbauer spectroscopy. From the variable-temperature Mössbauer effect, the Debye temperature was determined. The complexes have been characterized in solution by NMR ( 1H and 13C) spectroscopy. Vibrational, Mössbauer, and NMR data are discussed in terms of the proposed structures.

  17. Raman and infrared spectroscopic study of kamphaugite-(Y)

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo

    2015-05-01

    We have studied the carbonate mineral kamphaugite-(Y)(CaY(CO3)2(OH)·H2O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088 cm-1 provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the ν4 region offers further support for the non-equivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed.

  18. Raman spectroscopic study of plasma-treated salmon DNA

    SciTech Connect

    Lee, Geon Joon; Kim, Yong Hee; Choi, Eun Ha; Kwon, Young-Wan

    2013-01-14

    In this research, we studied the effect of plasma treatment on the optical/structural properties of the deoxyribonucleic acid (DNA) extracted from salmon sperm. DNA-cetyltrimethylammonium (CTMA) films were obtained by complexation of DNA with CTMA. Circular dichroism (CD) and Raman spectra indicated that DNA retained its double helical structure in the solid film. The Raman spectra exhibited several vibration modes corresponding to the nuclear bases and the deoxyribose-phosphate backbones of the DNA, as well as the alkylchains of CTMA. Dielectric-barrier-discharge (DBD) plasma treatment induced structural modification and damage to the DNA, as observed by changes in the ultraviolet-visible absorption, CD, and Raman spectra. The optical emission spectra of the DBD plasma confirmed that DNA modification was induced by plasma ions such as reactive oxygen species and reactive nitrogen species.

  19. [Spectroscopic studies of guanidine hydrochloride-induced unfolding of hemoglobin].

    PubMed

    Li, Jin-Jing; Tang, Qian; Cao, Hong-Yu; Zhang, Yu-Jiao; Zhang, Tao; Zheng, Xue-Fang

    2012-09-01

    In the present paper, based on the ultraviolet-visible (UV-Vis) absorption spectroscopy, fluorescence spectroscopy, and stopped flow-fluorescence spectroscopy, the authors studied the protein unfolding process of hemoglobin induced by GdmHcl. The experiments result shows that there were two different procedures about GdmHcl inducing hemoglobin unfolding from the evidences of UV-Vis absorption spectrum and fluorescence phase diagrams. Namely, the hemoglobin subunit exhibits depolymerization, forming the intermediates when incubated with GdmHcl at the concentration of 1. 0 mol x L(-1). With the increase in the concentration, various subunit structure became loose gradually, and the protoheme collapsed eventually. UV-Vis absorption spectroscopy indicates that the addition of reductant can cooperate with the depolymerization of hemoglobin subunit and the disaggregation of protoheme. The reductant results in the unfolding procedure that hemoglobin from "three-state model" turns into "two-state model".

  20. Spectroscopic STM studies of single gold(III) porphyrin molecules.

    PubMed

    Müllegger, Stefan; Schöfberger, Wolfgang; Rashidi, Mohammad; Reith, Lorenz M; Koch, Reinhold

    2009-12-16

    Low-temperature scanning tunneling microscopy, a well-established technique for single-molecule investigations in an ultrahigh vacuum environment, has been used to study the electronic properties of Au(III) 5,10,15,20-tetraphenylporphyrin (AuTPP) molecules on Au(111) at the submolecular scale. AuTPP serves as a model system for chemotherapeutically relevant Au(III) porphyrins. For the first time, real-space images and local scanning tunneling spectroscopy data of the frontier molecular orbitals of AuTPP are presented. A comparison with results from density functional theory reveals significant deviations from gas-phase behavior due to a non-negligible molecule/substrate interaction. We identify the oxidation state of the central metal ion in the adsorbed AuTPP as Au(3+).

  1. A spectroscopic study of the blue stragglers in M67

    NASA Astrophysics Data System (ADS)

    Liu, G. Q.; Deng, L.; Chávez, M.; Bertone, E.; Davo, A. Herrero; Mata-Chávez, M. D.

    2008-10-01

    Based on spectrophotometric observations from the Guillermo Haro Observatory (Cananea, Mexico), a study of the spectral properties of the complete sample of 24 blue straggler stars (BSs) in the old Galactic open cluster M67 (NGC 2682) is presented. All spectra, calibrated using spectral standards, were recalibrated by means of photometric magnitudes in the Beijing-Arizona-Taipei-Connecticut system, which includes fluxes in 11 bands covering ~3500-10000 Å. The set of parameters was obtained using two complementary approaches that rely on a comparison of the spectra with (i) an empirical sample of stars with well-established spectral types and (ii) a theoretical grid of optical spectra computed at both low and high resolution. The overall results indicate that the BSs in M67 span a wide range in Teff(~ 5600 -12600 K) and surface gravities that are fully compatible with those expected for main-sequence objects (log g = 3.5 -5.0 dex).

  2. Enhanced Raman spectroscopic study of rotational isomers on metal surfaces

    NASA Technical Reports Server (NTRS)

    Loo, B. H.; Lee, Y. G.; Frazier, D. O.

    1986-01-01

    Surfaced-enhanced Raman spectroscopy has been used to study rotational isomers of succinonitrile and N-methyl-thioacetamide on Cu and Ag surfaces. Both the gauche and trans conformers of succinonitrile are found to chemisorb on the metal surface. The doubly degenerate nu(C-triple bond-N) in the free molecules is removed when succinonitrile adsorbs on copper, which indicates that the two (C-triple bond-N) groups are no longer chemically equivalent. Both conformers are found to coordinate to the copper surface through the pi system of one of the two (C-triple bond-N) groups. In the case of N-methyl-thioacetamide, the population of the cis isomer is greatly increased on Cu and Ag surfaces. This is probably due to surface-induced cis-trans isomerization, in which the predominant trans isomer is converted to the cis isomer.

  3. Computational and vibrational spectroscopic studies of ipratropium bromide.

    PubMed

    Ali, H R H; Edwards, H G M; Kendrick, J; Scowen, I J

    2009-02-01

    In this study, ipratropium bromide is investigated using vibrational spectroscopy and quantum chemical calculations. The structure of ipratropium bromide was optimised using density functional theory calculations and the geometry optimisation has been carried out on two conformations with and without intramolecular hydrogen bonding. Infrared and Raman spectra were calculated from the optimised structures. Many modes in the calculated spectra could be matched with the experimental spectra and a description of the modes is given. By analysis of the theoretical vibrational modes, it is shown that ipratropium bromide specimens are likely to be a mixture of the two conformations with and without intramolecular hydrogen bonding. In addition, several spectral features and band intensities in the CH and OH stretching regions are explained. Quantum mechanical calculations allowed improved understanding of ipratropium bromide and its vibrational spectra.

  4. Conformational analysis and vibrational spectroscopic studies on dapsone

    NASA Astrophysics Data System (ADS)

    Ildiz, Gulce Ogruc; Akyuz, Sevim

    2012-11-01

    In this study, the theoretical conformation analysis of free dapsone has been performed by single point energy calculations at both semi-empirical PM3 and DFT/B3LYP-3-21G theory levels and three stable conformers were determined. Both the IR and Raman spectra of the molecule in solid phase have been recorded. The IR intensities and harmonic vibrational wavenumbers of each conformer were calculated by DFT method at B3LYP/6-31++G(d,p) theory level. For the fundamental characterization, the total energy distribution (TED) calculations of the vibrational modes were done using parallel quantum mechanic solution program (SQM) and the fundamental modes were assigned. The theoretical results are in agreement with the experimental ones.

  5. Raman spectroscopic study of ancient South African domestic clay pottery.

    PubMed

    Legodi, M A; de Waal, D

    2007-01-01

    The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al2Si2O5(OH)5), illite (KAl4(Si7AlO20)(OH)4), feldspar (K- and NaAlSi3O8), quartz (alpha-SiO2), hematite (alpha-Fe2O3), montmorillonite (Mg3(Si,Al)4(OH)2 x 4.5 5H(2)O[Mg]0.35), and calcium silicate (CaSiO3). Gypsum (CaSO4 x 2H2O) and calcium carbonates (most likely calcite, CaCO3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO(2)) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 degrees C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively.

  6. Raman spectroscopic study of ancient South African domestic clay pottery

    NASA Astrophysics Data System (ADS)

    Legodi, M. A.; de Waal, D.

    2007-01-01

    The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al 2Si 2O 5(OH) 5), illite (KAl 4(Si 7AlO 20)(OH) 4), feldspar (K- and NaAlSi 3O 8), quartz (α-SiO 2), hematite (α-Fe 2O 3), montmorillonite (Mg 3(Si,Al) 4(OH) 2·4.5H 2O[Mg] 0.35), and calcium silicate (CaSiO 3). Gypsum (CaSO 4·2H 2O) and calcium carbonates (most likely calcite, CaCO 3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO 2) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO 4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 °C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively.

  7. Raman spectroscopic studies of carbon in extra-terrestrial materials

    NASA Technical Reports Server (NTRS)

    Macklin, John; Brownlee, Donald; Chang, Sherwood; Bunch, Ted

    1990-01-01

    The measurements obtained here indicate ways in which micro-Raman spectroscopy can be used to elucidate structural characteristics and distribution of carbon in meteorites and interplanetary dust particles (IDPs). Existing information about structurally significant aspects of Raman measurements of graphite is combined with structurally relevant findings from the present micro-Raman studies of carbons prepared by carbonization of polyvinylidine chloride (PVDC) at various temperatures and natural material, as well as several acid residues from the Allende and Murchison meteorites in order to establish new spectra-structure relationships. Structural features of many of the materials in this study have been measured by x ray analysis and electron microscopy: thus, their structural differences can be directly correlated with differences in the Raman spectra. The spectral parameters consequently affirmed as indicators of structure are used as a measure of structure in materials that have unknown carbon structure, especially IDPs. The unique applicability of micro-Raman spectroscopy is realized not only in the ability to conveniently measure spectra of micron-size IDPs, but also micro-sized parts of an inhomogeneous material. Microcrystalline graphite is known to give Raman spectra that differ dependent on crystallite size (see e.g., Lespade, et. al., 1984, or Nemanich and Solin, 1979). The spectral changes that accompany decreasing particle size include increase in the ratio (R) of the intensity of the band near 1350 cm(-1) (D band) to that of the band near 1600 cm(-1) (G band) increase in the half width of the D band (wD) increase in the frequency maximum of the G band and increase in the half-width (wG) of the 2nd order band near 2700 cm(-1) (G) band.

  8. Spectroscopic and photometric characteristics of stars in the field of the cluster vdB 130

    NASA Astrophysics Data System (ADS)

    Tatarnikova, A. A.; Tatarnikov, A. M.; Sitnik, T. G.; Egorov, O. V.

    2016-12-01

    The observational data for 24 stars toward the young cluster vdB 130 are analyzed. The spectroscopic and photometric BV RIJHK observations have been carried out with the following telescopes: 6-m at the Special Astrophysical Observatory of the Russian Academy of Sciences, 60-cm at the Southern Station of the Moscow State University, and 2.5-m at the Caucasus Observatory of the Sternberg Astronomical Institute of theMoscow State University. Nine stars previously selected as cluster members have been found to belong to different subtypes of type B. A minimum color excess toward the cluster, E( B - V) = 0.9 mag, has been revealed for the vdB 130 stars lying outside the molecular cloud. Maximum color excesses, E( B - V) = 1.3-1.4 mag, have been found in the spectra of cluster stars 1r and 5r observed in dust blobs. Inside the cluster R v is shown to differ from the standard one. The overwhelming majority of the remaining investigated stars belong to late types and have minor color excesses (≤0.3) typical of close distances.

  9. Spectroscopic study of intermolecular complexes between FAD and some β-carboline derivatives

    NASA Astrophysics Data System (ADS)

    Codoñer, Armando; Monzó, Isidro S.; Tomás, Francisco; Valero, Rosa

    The formation of molecular complexes between flavine adenine dinucleotide (FAD) and some β-carboline derivatives [antidepressant drugs that have a pronounced inhibition of monoamine oxidase (MAO)] has been studied by using electronic absorption and fluorescence spectroscopic methods. Thermodynamic parameters have been determined from the values of association constants for the molecular complexes at various temperatures. The influence of substituents in the β-carboline molecule on the stability of the complexes formed was also investigated.

  10. Ir Spectroscopic Studies on Microsolvation of HCl by Water

    NASA Astrophysics Data System (ADS)

    Mani, Devendra; Schwan, Raffael; Fischer, Theo; Dey, Arghya; Kaufmann, Matin; Redlich, Britta; van der Meer, Lex; Schwaab, Gerhard; Havenith, Martina

    2016-06-01

    Acid dissociation reactions are at the heart of chemistry. These reactions are well understood at the macroscopic level. However, a microscopic level understanding is still in the early stages of development. Questions such as 'how many H_2O molecules are needed to dissociate one HCl molecule?' have been posed and explored both theoretically and experimentally.1-5 Most of the theoretical calculations predict that four H_2O molecules are sufficient to dissociate one HCl molecule, resulting in the formation of a solvent separated H_3O+(H_2O)3Cl- cluster.1-3 IR spectroscopy in helium nanodroplets has earlier been used to study this dissociation process.3-5 However, these studies were carried out in the region of O-H and H-Cl stretch, which is dominated by the spectral features of undissociated (HCl)m-(H_2O)n clusters. This contributed to the ambiguity in assigning the spectral features arising from the dissociated cluster.4,5 Recent predictions from Bowman's group, suggest the presence of a broad spectral feature (1300-1360 wn) for the H_3O+(H_2O)3Cl- cluster, corresponding to the umbrella motion of H_3O+ moiety.6 This region is expected to be free from the spectral features due to the undissociated clusters. In conjunction with the FELIX laboratory, we have performed experiments on the (HCl)m(H_2O)n (m=1-2, n≥4) clusters, aggregated in helium nanodroplets, in the 900-1700 wn region. Mass selective measurements on these clusters revealed the presence of a weak-broad feature which spans between 1000-1450 wn and depends on both HCl as well as H_2O concentration. Measurements are in progress for the different deuterated species. The details will be presented in the talk. References: 1) C.T. Lee et al., J. Chem. Phys., 104, 7081 (1996). 2) H. Forbert et al., J. Am. Chem. Soc., 133, 4062 (2011). 3) A. Gutberlet et al., Science, 324, 1545 (2009). 4) S. D. Flynn et al., J. Phys. Chem. Lett., 1, 2233 (2010). 5) M. Letzner et al., J. Chem. Phys., 139, 154304 (2013). 6) J. M

  11. Spectroscopic study of neodymium doped lead-bismuth-borate glasses

    NASA Astrophysics Data System (ADS)

    Pasha, Altaf; Dayani, P.; Negalur, Mahesh; Swamy, Manjunatha; Abhiram, J.; Rajaramakrishna, R.

    2016-05-01

    This paper reports on different physical and optical properties of rare earth doped heavy metal oxide glasses. The glass composition of 10Bi2O3-30PbO-60B2O3-xNd2O3 where x = 0, 0.1, 0.2, 0.5 and 1 (in mol %) has been synthesized using melt-quenching technique. Refractive index measurements for these glasses were done and physical parameters were studied. Structural properties of these glasses were analysed through infrared spectra that was recorded between 1600cm-1 and 300cm-1 in transmission mode. The optical absorption spectra were recorded in the wavelength range from 300 to 700 nm. The transitions originated from ground state energy 4I9/2. The energy level analysis has been carried out by considering absorption spectral bands. The results thus obtained are comparable with reports on similar glasses, indicating that the prepared glasses may have potential laser applications.

  12. A spectroscopic study of the open cluster NGC 6250

    NASA Astrophysics Data System (ADS)

    Martin, A. J.; Stift, M. J.; Fossati, L.; Bagnulo, S.; Scalia, C.; Leone, F.; Smalley, B.

    2017-04-01

    We present the chemical abundance analysis of 19 upper main-sequence stars of the young open cluster NGC 6250 (log t ∼ 7.42 yr). This work is part of a project aimed at setting observational constraints on the theory of atomic diffusion in stellar photospheres, by means of a systematic study of the abundances of the chemical elements of early F-, A- and late B-type stars of well-determined age. Our data set consists of low-, medium- and high-resolution spectra obtained with the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument of the ESO Very Large Telescope (VLT). To perform our analysis, we have developed a new suite of software tools for the chemical abundance analysis of stellar photospheres in local thermodynamical equilibrium. Together with the chemical composition of the stellar photospheres, we have provided new estimates of the cluster mean radial velocity, proper motion, refined the cluster membership, and we have given the stellar parameters including masses and fractional age. We find no evidence of statistically significant correlation between any of the parameters, including abundance and cluster age, except perhaps for an increase in Ba abundance with cluster age. We have proven that our new software tool may be successfully used for the chemical abundance analysis of large data sets of stellar spectra.

  13. A theoretical and spectroscopic study of conformational structures of piroxicam

    NASA Astrophysics Data System (ADS)

    Souza, Kely Ferreira de; Martins, José A.; Pessine, Francisco B. T.; Custodio, Rogério

    2010-02-01

    Piroxicam (PRX) has been widely studied in an attempt to elucidate the causes and mechanisms of its side effects, mainly the photo-toxicity. In this paper fluorescence spectra in non-protic solvents and different polarities were carried out along with theoretical calculations. Preliminary potential surfaces of the keto and enol forms were obtained at AM1 level of theory providing the most stable conformers, which had their structure re-optimized through the B3LYP/CEP-31G(d,p) method. From the optimized structures, the electronic spectra were calculated using the TD-DFT method in vacuum and including the solvent effect through the PCM method and a single water molecule near PRX. A new potential surface was constructed to the enol tautomer at DFT level and the most stable conformers were submitted to the QST2 calculations. The experimental data showed that in apolar media, the solution fluorescence is raised. Based on conformational analysis for the two tautomers, keto and enol, the results indicated that the PRX-enol is the main tautomer related to the drug fluorescence, which is reinforced by the spectra results, as well as the interconvertion barrier obtained from the QST2 calculations. The results suggest that the PRX one of the enol conformers presents great possibility of involvement in the photo-toxicity mechanisms.

  14. Luminescence and spectroscopic studies of halosulfate phosphors: a review.

    PubMed

    Gedam, S C; Thakre, P S; Dhoble, S J

    2015-03-01

    This review discusses the photoluminescence (PL) characteristics of halosulfate phosphors developed by us. Halosulfate phosphors KCaSO4 Cl:X,Y (X = Eu or Ce; Y = Dy or Mn) and Na6 (SO4 )2 FCl (doped with Dy, Ce or Eu) were prepared using a solid-state diffusion method. The mechanism of energy transfer from Eu(2+) →Dy(3+) , Ce(3+) →Dy(3+) and Ce(3+) →Mn(2+) has also been studied. Dy(3+) emission in the host at 475 and 570 nm is observed due to (4) F9/2 →(6) H15/2 and (4) F9/2 →(6) H13/2 transition, whereas the PL emission spectra of Na6 (SO4 )2 FCl:Ce phosphor shows Ce(3+) emission at 322 nm due to 5d→4f transition of the Ce(3+) ion. The main property of KCaSO4 Cl is its very high sensitivity, particularly when doped by Dy, Mn or Pb activators. This review also discusses the PL characteristics of some new phosphors such as LiMgSO4 F, Na6 Pb4 (SO4 )6 Cl2 , Na21 Mg(SO4 )10 Cl3 and Na15 (SO4 )5 F4 Cl.

  15. Spectroscopic studies of aluminosilicate formation in tank waste simulants

    SciTech Connect

    Su, Y.; Wang, L.; Bunker, B.C.; Windisch, C.F.

    1997-12-31

    Aluminosilicates are one of the major class of species controlling the volume of radioactive high-level waste that will be produced from future remediation at Hanford site. Here the authors present studies of the phases and structures of aluminosilicates as a function of sludge composition using X-ray powder diffraction, solid state {sup 27}Al and {sup 29}Si NMR, and Raman spectroscopy. The results show that the content of NaNO{sub 3} in solution has significant effects on the nature of the insoluble aluminosilicate phases produced. It was found that regardless of the initial Si:Al ratio, nitrate cancrinite was the main phase formed in the solution with pH of 13.5 and 5 M NaNO{sub 3}. However, at lower NaNO{sub 3} concentration with initial Si:Al ratios of 1.1, 2.2, and 11.0 in the solutions, a range of aluminosilicate zeolites was produced with Si:Al ratios of 1.1, 1.3, and 1.5, respectively. Lowering the solution pH appears to promote the formation of amorphous aluminosilicates. The results presented here are important for the prediction of the solubility and dissolution rate of Al in tank wastes.

  16. [The IR spectroscopic study of hydrothermal synthetic KTP].

    PubMed

    Xie, Hao; Pei, Jing-Cheng; Qi, Li-Jian; Zhong, Zeng-Qiu

    2010-05-01

    In the present paper, different-generation hydrothermally grown KTP crystals were tested by the Nicolet 550 type FIR spectrometer with the reflective technique. They were studied on different crystal faces. Since the hydrothermally grown KTP crystal usually grows (100), (011) and (201) crystal faces, these faces were tested in different-generation products, and they were tested by two spectral wave bands, 2 000-4 000 and 400-2 000 cm(-1). The figures were compared with the flux-melt grown KTP crystal. In addition, making reference to the method of calculation about the consistence of OH- in quartz, the consistence of OH- in different -generation hydrothermally grown KTP crystals was estimated. In the hydrothermal grown KTP crystals, the stretching vibration of OH- shows distinct directivity characteristic. The absorption at [100] direction is obvious and the frequency is about 30 cm(-1) higher than the flux-melt grown KTP. Each new generation weakened the consistency of OH-, which restrained the growth of the KTP crystal. Accordingly, increasing the purity of rough materials plays a very important role in improving the quality of the crystals.

  17. Micro-Raman spectroscopic study of thyroid tissues.

    PubMed

    Medeiros Neto, Lázaro Pinto; das Chagas E Silva de Carvalho, Luis Felipe; Santos, Laurita Dos; Tellez Soto, Cláudio Alberto; de Azevedo Canevari, Renata; de Oliveira Santos, André Bandiera; Mello, Evandro Sobroza; Pereira, Marina Aparecida; Cernea, Cláudio Roberto; Brandão, Lenine Garcia; Martin, Aírton Abrahão

    2017-03-01

    Thyroid carcinomas are the most common endocrine malignancy. Inconclusive results for the analysis of malignancies are an issue in the diagnosis of thyroid carcinomas; 20% of thyroid cancer diagnoses are indeterminate or suspicious, resulting in a surgical procedure without immediate need. The use of Raman spectroscopy may help improve the diagnosis of thyroid carcinoma. In this study, 30 thyroid samples, including normal thyroid, goiter and thyroid cancer, were analyzed by confocal Raman spectroscopy. Principal component analysis (PCA), linear discriminant analysis (LDA) with cross validation and binary logistic regression (BLR) analysis were applied to discriminate among tissues. Significant discrimination was observed, with a consistent rate of concordant pairs of 89.2% for normal thyroid versus cancer, 85.7% for goiter versus cancer and 80.6% for normal thyroid versus goiter using just the amide III region. Raman spectroscopy was thus proven to be an important and fast tool for the diagnosis of thyroid tissues. The spectral region of 1200-1400cm(-1) discriminated normal versus goiter tissues despite the great similarity of these tissues.

  18. Synthesis, spectroscopic, thermogravimetric and antimicrobial studies of mixed ligands complexes

    NASA Astrophysics Data System (ADS)

    Mahmoud, Walaa H.; Mahmoud, Nessma F.; Mohamed, Gehad G.; El-Sonbati, Adel Z.; El-Bindary, Ashraf A.

    2015-09-01

    An interesting series of mixed ligand complexes have been synthesized by the reaction of metal chloride with guaifenesin (GFS) in the presence of 2-aminoacetic acid (HGly) (1:1:1 molar ratio). The elemental analysis, magnetic moments, molar conductance, spectral (UV-Vis, IR, 1H NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structure of GFS is optimized theoretically and the quantum chemical parameters are calculated. The IR showed that the ligand (GFS) acts as monobasic tridentate through the hydroxyl, phenoxy etheric and methoxy oxygen atoms and co-ligand (HGly) as monobasic bidentate through the deprotonated carboxylate oxygen atom and nitrogen atom of amino group. The molar conductivities showed that all the complexes are non-electrolytes except Cr(III) complex is electrolyte. Electronic and magnetic data proposed the octahedral structure for all complexes under investigation. ESR spectrum for Cu(II) revealed data which confirm the proposed structure. Antibacterial screening of the compounds were carried out in vitro on gram positive (Bacillus subtilis and Staphylococcus aureus), gram negative (Escherichia coli and Neisseria gonorrhoeae) bacteria and for in vitro antifungal activity against Candida albicans organism. However, some complexes showed more chemotherapeutic efficiency than the parent GFS drug. The complexes were also screened for their in vitro anticancer activity against the breast cell line (MFC7) and the results obtained showed that they exhibit a considerable anticancer activity.

  19. Borax methylene blue: a spectroscopic and staining study.

    PubMed

    Donaldson, P T; Russo, A; Reynolds, C; Lillie, R D

    1978-07-01

    Borax methylene blue is quite stable at room temperatures of 22-25 C. At 30 C polychroming is slow; during 50 days in a water bath at this temperature the absorption peak moves from 665 to 656 nm. At 35 C, the absorption peak reaches 660 nm in 7 days, 654 nm in 14. At 60 C polychroming is rapid, the absorption peak reaching 640-620 nm in 3 days. When the pH of the borax methylene blue solutions, normally about 9.0, is adjusted to pH 6.5, the absorption peak remains at 665 nm even when incubated at 60 C for extended periods. When used as a blood stain 0.4 ml borax methylene blue (1% methylene blue in 1% borax), 4 ml acetone, 2 ml borax-acid phosphate buffer to bring the solution to pH 6.5, and distilled water to make 40 ml, with 0.2 ml 1% eosin added just before using, an excellent Nocht-Giemsa type stain is achieved after 30 minutes staining. The material plasmodia P. falciparum, P. vivax, and P. berghei stain moderate blue with dark red chromatin and green to black pigment granules. The study confirms Malachowski's 1891 results and explains Gautier's 1896-98 failure to duplicate it.

  20. A Spectroscopic Study of the Blue Component of Albireo

    NASA Astrophysics Data System (ADS)

    Whight, Kenneth R.

    2013-05-01

    This paper describes an investigation into what can be learned about the physical properties of the blue component of the Albireo double star system from both low (150 lines/mm) and high (2400 lines/mm) resolution spectra, based on the simple model that the star is a rotating uniformly emitting oblate spheroid with a photosphere that is a single layer in thermal equilibrium. The blue component of Albireo is an interesting target in that it exhibits emission at both Halpha and Hbeta wavelengths; this emission is believed to originate from an equatorial decretion disk spun off from the star. The aim of this work was to split the observed high resolution spectra into an absorption component, from the star, and an emission component, from the disk. To achieve this aim the continuum spectrum was modeled as a "black body" to obtain an effective temperature and the Hgamma absorption line was studied to obtain values for the star's model parameters. These results were then used to predict the expected absorption at Halpha and Hbeta wavelengths. Measured Halpha and Hbeta lines were then divided by their expected absorption lines to reveal the pure disk emission for further analysis.

  1. A spectroscopic study of laser ablation plasma from Mo target

    NASA Astrophysics Data System (ADS)

    Jakubowska, Katarzyna; Kubkowska, Monika; Blagoev, Alexander; Rosiński, Marcin; Parys, Piotr; Gąsior, Paweł

    2014-05-01

    The goal of this contribution is to present time-resolved optical spectroscopy studies of laser ablation of the Mo target with ˜ 3.5 ns, 0.4 J pulses delivered by the Nd-YAG laser system at 1.06 μm. The sample was placed in a vacuum chamber under 5 × 10-5 mbar pressure and irradiated, with power densities varied up to 22.7 GW cm-2. The ion emission from the plasma plume was measured using an electrostatic ion energy analyzer (IEA) and ion collector, which allowed us to estimate the ion kinetic energy and charge independent of the applied power densities. The signal collected by the IEA indicated the presence of molybdenum ions up to eight-ion charge. Simultaneously after the ion emission, the optical spectra acquired within 2 μs of exposure time were observed in the wavelength range from 200 to 1000 nm with a Mechelle 5000 spectrometer equipped with an iCCD (iStar) detector. The plasma electron temperature was estimated from a Boltzmann plot based on the registered spectra as well as from the ion measurements.

  2. Spectroscopic study on binding of rutin to human serum albumin

    NASA Astrophysics Data System (ADS)

    Pastukhov, Alexander V.; Levchenko, Lidiya A.; Sadkov, Anatoli P.

    2007-10-01

    Steady-state and time-resolved fluorescence spectroscopy techniques were used to study the interaction of the flavonoid rutin with human serum albumin (HSA) as well as spectral properties of the protein-bound flavonoid. Both quenching of the intrinsic fluorescence of the protein (Trp214) and the ligand fluorescence, appearing upon complexation with HSA, were used to determine binding parameters. The binding constant determined from the quenching of the Trp214 fluorescence by rutin is equal to 6.87 ± 0.22 × 10 4 M -1 and that obtained from the fluorescence of HSA-bound rutin is 3.8 ± 0.4 × 10 4 M -1. Based on the Job plot analysis, the 1:1 binding stoichiometry for the HSA-rutin complex was determined. The efficient quenching of the Trp214 fluorescence by rutin, fluorescence resonance energy transfer from excited Trp214 to rutin, and competitive binding of warfarin indicate that the binding site for the flavonoid is situated within subdomain IIA of HSA. The presence of the sugar moiety in the flavonoid molecule reduces affinity of rutin for binding to HSA but does not affect the binding stoichiometry and location of the binding site compared with aglycone analogues.

  3. High resolution spectroscopic study of BeΛ10

    DOE PAGES

    Gogami, T.; Chen, C.; Kawama, D.; ...

    2016-03-10

    Spectroscopy of amore » $$^{10}_{\\Lambda}$$Be hypernucleus was carried out at JLab Hall C using the $$(e,e^{\\prime}K^{+})$$ reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of 0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using the $$p(e,e^{\\prime}K^{+})\\Lambda,\\Sigma^{0}$$ reactions allowed us to determine the energy levels, and the binding energy of the ground state peak (mixture of 1$$^{-}$$ and 2$$^{-}$$ states) was obtained to be B$$_{\\Lambda}$$=8.55$$\\pm$$0.07(stat.)$$\\pm$$0.11(sys.) MeV. Furthermore, the result indicates that the ground state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on charge symmetry breaking effect in the $$\\Lambda N$$ interaction.« less

  4. Raman spectroscopic studies of gas/aerosol chemical reactions

    SciTech Connect

    Aardahl, C.L.; Davis, E.J.

    1995-12-31

    Reactions between sorbent particles and SO{sub 2} can be used to reduce atmospheric pollution either by {open_quotes}dry scrubbing{close_quotes} or {open_quotes}wet scrubbing{close_quotes} processes. This paper reports Raman spectroscopy results for single electrodynamically levitated droplets of NaOH reacting with SO{sub 2} and studies of the dehydration reactions of some hygroscopic salt species. The NaOH/SO{sub 2} reaction products and the liquid or solid state of the products are shown to depend on the gas phase SO{sub 2} concentration. Deliquesced particles of NaOH exhibit enhanced light scattering intensities associated with morphological resonances of the incident laser light, but crystalline materials show no such resonances. Raman-active hygroscopic salts exhibit bond frequencies characteristic of the stretching vibrations of the anionic group, but these frequencies are different in the presence of water because hydrogen bonding changes the bond force. This allows efficient tracking of the dehydration reactions in hygroscopic aerosols by Raman spectroscopy as the intensities of the two different modes are related to the degree of dehydration in the particle.

  5. Spectroscopic studies on the antioxidant activity of ellagic acid

    NASA Astrophysics Data System (ADS)

    Kilic, Ismail; Yeşiloğlu, Yeşim; Bayrak, Yüksel

    2014-09-01

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2‧-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTSrad + scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

  6. Spectroscopic studies on the antioxidant activity of ellagic acid.

    PubMed

    Kilic, Ismail; Yeşiloğlu, Yeşim; Bayrak, Yüksel

    2014-09-15

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTS+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

  7. HPLC assisted Raman spectroscopic studies on bladder cancer

    NASA Astrophysics Data System (ADS)

    Zha, W. L.; Cheng, Y.; Yu, W.; Zhang, X. B.; Shen, A. G.; Hu, J. M.

    2015-04-01

    We applied confocal Raman spectroscopy to investigate 12 normal bladder tissues and 30 tumor tissues, and then depicted the spectral differences between the normal and the tumor tissues and the potential canceration mechanism with the aid of the high-performance liquid chromatographic (HPLC) technique. Normal tissues were demonstrated to contain higher tryptophan, cholesterol and lipid content, while bladder tumor tissues were rich in nucleic acids, collagen and carotenoids. In particular, β-carotene, one of the major types of carotenoids, was found through HPLC analysis of the extract of bladder tissues. The statistical software SPSS was applied to classify the spectra of the two types of tissues according to their differences. The sensitivity and specificity of 96.7 and 66.7% were obtained, respectively. In addition, different layers of the bladder wall including mucosa (lumps), muscle and adipose bladder tissue were analyzed by Raman mapping technique in response to previous Raman studies of bladder tissues. All of these will play an important role as a directive tool for the future diagnosis of bladder cancer in vivo.

  8. Synchronous fluorescence spectroscopic study of solvatochromic curcumin dye

    NASA Astrophysics Data System (ADS)

    Patra, Digambara; Barakat, Christelle

    2011-09-01

    Curcumin, the main yellow bioactive component of turmeric, has recently acquired attention by chemists due its wide range of potential biological applications as an antioxidant, an anti-inflammatory, and an anti-carcinogenic agent. This molecule fluoresces weakly and poorly soluble in water. In this detailed study of curcumin in thirteen different solvents, both the absorption and fluorescence spectra of curcumin was found to be broad, however, a narrower and simple synchronous fluorescence spectrum of curcumin was obtained at Δ λ = 10-20 nm. Lippert-Mataga plot of curcumin in different solvents illustrated two sets of linearity which is consistent with the plot of Stokes' shift vs. the ET30. When Stokes's shift in wavenumber scale was replaced by synchronous fluorescence maximum in nanometer scale, the solvent polarity dependency measured by λSFSmax vs. Lippert-Mataga plot or ET30 values offered similar trends as measured via Stokes' shift for protic and aprotic solvents for curcumin. Better linear correlation of λSFSmax vs. π* scale of solvent polarity was found compared to λabsmax or λemmax or Stokes' shift measurements. In Stokes' shift measurement both absorption/excitation as well as emission (fluorescence) spectra are required to compute the Stokes' shift in wavenumber scale, but measurement could be done in a very fast and simple way by taking a single scan of SFS avoiding calculation and obtain information about polarity of the solvent. Curcumin decay properties in all the solvents could be fitted well to a double-exponential decay function.

  9. Influence of environment on piroxicam polymorphism: vibrational spectroscopic study.

    PubMed

    Taddei, P; Torreggiani, A; Simoni, R

    2001-01-01

    FTIR and FT-Raman spectroscopies were used to evaluate the mechanism of transformation of piroxicam into its different forms (alpha, beta, and monohydrate), depending on the environment. These vibrational techniques allowed us to identify the forms of piroxicam that crystallize from different solvents at different cooling rates and the conformation of the drug in some of its derivatives: piroxicam hydrochloride, piroxicam thallium and sodium salt hemihydrates, and piroxicam sodium salt. The usefulness of Raman spectroscopy in characterizing piroxicam:beta-cyclodextrin (PbetaCD) inclusion compounds was described. The Raman spectrum of 1:2 PbetaCD was discussed in comparison with that of the corresponding piroxicam sodium salt containing inclusion compound (1:2 PNabetaCD) in order to study the influence of the piroxicam derivative used on the structure of the inclusion compound. The Raman results showed that in both of the inclusion compounds the piroxicam mainly assumes the zwitterionic structure typical of a monohydrate; therefore, the kind of derivative used does not affect the conformation of the drug in its inclusion compound. The effect of the method of synthesis utilized (freeze-drying or freeze-thaw cycling) to obtain 1:2.5 PbetaCD was investigated. The inclusion compound obtained by freeze-thaw cycling proved to be more crystalline and to contain a higher amount of the beta form than the freeze-dried inclusion compound. Raman spectroscopy proved to be a useful technique for evaluating the effectiveness of the manufacturing process in relation to the pharmaceutical properties of the drug and to the nondestructive and noninvasive on-line quality control of the industrial products.

  10. Reaction and spectroscopic study of supported metal oxide catalysts

    NASA Astrophysics Data System (ADS)

    Ramani, Narayanan C.

    The role of surface structure, cation reducibility, surface acidity and the effect of the support was examined in the reaction of 1-butene over well characterized, supported metal oxide catalysts. Cr, Mo and W oxides supported on SiOsb2 were used to study the effect of structure, surface acidity and cation reducibility in the isomerization and selective oxidation of 1-butene. Supported oxides of Mo on TiOsb2,\\ Alsb2Osb3 and SiOsb2 were used to understand the role of the support in the selective oxidation of 1-butene. The surface acidity of SiOsb2 supported Cr, Mo, W and V oxide catalysts was examined by pyridine adsorption. Existing theoretical models of acidity were compared against experimental data. Over Mo(VI)/SiOsb2 and W(VI)/SiOsb2, isomerization through both a Bronsted catalyzed pathway and an allylic pathway were observed, while only the allylic pathway was observed over Cr(VI)/SiOsb2. The greater reducibility of the Cr cation compared to Mo and W cations was identified as the reason for the allylic pathway being dominant over Cr(VI)/SiOsb2. Cation reducibility was again seen to play an important role in the selective oxidation of 1-butene over SiOsb2 supported metal oxides. The turn over frequencies for 1,3-butadiene formation followed the trend in red-ox ability, with Cr > Mo > W. The activity to 1,3-butadiene formation did not change with increasing weight loading of Mo over TiOsb2 and Alsb2Osb3 supports. An analysis of the turn over frequencies of the supports and the supported cations revealed that a support effect, through the bridging oxygen ligand, dominated the intrinsic cation reducibility of Mo for these catalysts. The existence of Bronsted acidity over SiOsb2 supported Cr, Mo and V oxides was shown by an analysis of the OH region of the infrared spectrum, and by the adsorption of 1-butene and pyridine. Existing theoretical models for Bronsted acidity over supported metal oxides were shown to be inadequate to describe the observed results over

  11. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L{sub cm} (I), {beta}{sup 18} (II), and {alpha}{sup AP-B} (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A{sub max} = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  12. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L[sub cm] (I), [beta][sup 18] (II), and [alpha][sup AP-B] (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A[sub max] = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  13. A spectroscopic and dynamical study of binary and other Cepheids

    NASA Astrophysics Data System (ADS)

    Petterson, Orlon King Lee

    High resolution observations have been made of a number of southern Cepheids to make an observational and theoretical study of Cepheid variables using radial velocities. The stars studied were part of a long term programme to observe southern variable stars, from which a valuable database of radial velocities gathered over a long period were available. Sixteen échelle spectrograph orders in the wavelength region 5400 - 8600Å were used, which included a number of absorption lines covering a range of species and excitation potentials. The line bisector technique was used to measure stellar and telluric lines and to obtain radial velocities. To improve the precision of the radial velocities we used telluric lines to calibrate the observations to a common reference frame. The radial velocities have a precision of ~300ms-1 allowing the detection of velocity differences of ~1 kms-1 with confidence. The radial velocity data obtained at Mount John University Observatory (MJUO) was combined with data from various sources to determine the orbits of any Cepheids exhibiting orbital motion. The various orbital parameters were determined for a number of systems and where radial velocities for the companions exist, some estimate of the mass was made. The precision of the radial velocities obtained from MJUO also allowed us to search for line level effects for a number of species among the Cepheid spectra. A number of IAU standard stars were observed to calibrate the radial velocities obtained at MJUO to the IAU standard scale. The radial velocities from MJUO were found not to differ significantly from the IAU values. Binary Cepheids are particularly useful in the determination of Cepheid masses, which are still an active topic for astronomical research. The value of the MJUO data was that it provided a consistent set of data against which other sources of data could be compared. For 8 of the Cepheids new or improved orbital solutions were found. They are Y Car, YZ Car, AX Cir

  14. Spectroscopic Measurement of Ion Flow During Merging Start-up of Field-Reversed Configuration

    NASA Astrophysics Data System (ADS)

    Oka, Hirotaka; Inomoto, Michiaki; Tanabe, Hiroshi; Annoura, Masanobu; Ono, Yasushi; Nemoto, Koshichi

    2012-10-01

    The counter-helicity merging method [1] of field-reversed configuration (FRC) formation involves generation of bidirectional toroidal flow, known as a ``sling-shot.'' In two fluids regime, reconnection process is strongly affected by the Hall effect [2]. In this study, we have investigated the behavior of toroidal bidirectional flow generated by the counter-helicity merging in two-fluids regime. We use 2D Ion Doppler Spectroscopy to mesure toroidal ion flow during merging start-up of FRC from Ar gas. We defined two cases: one case with a radially pushed-in X line (case I) and the other case with a radially pushed-out X line(case O). The flow during the plasma merging shows radial asymmetry, as expected from the magnetic measurement, but finally relaxes to a unidirectional flow in plasma current direction in both cases. We observed larger toroidal flow in the plasma current direction in case I after FRC is formed, though the FRC in case O has larger magnetic flux. These results suggest that more ions are lost during merging start-up in case I. This selective ion loss might account for stability and confinement of FRCs probably maintained by high energy ions.[4pt] [1] Y. Ono, et al., Nucl. Fusion 39, pp. 2001-2008 (1999).[0pt] [2] M. Inomoto, et al., Phys. Rev. Lett., 97, 135002, (2006)

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  16. A Spectroscopic Study of the Extreme Black Widow PSR J1311-3430

    NASA Astrophysics Data System (ADS)

    Romani, Roger W.; Filippenko, Alexei V.; Cenko, S. Bradley

    2015-05-01

    We report on a series of spectroscopic observations of PSR J1311-3430, an extreme black-widow gamma-ray pulsar with a helium-star companion. In a previous study we estimated the neutron star mass as {{M}NS}=2.68+/- 0.14 {{M}⊙ } (statistical error), based on limited spectroscopy and a basic (direct heating) light-curve model; however, much larger model-dependent systematics dominate the mass uncertainty. Our new spectroscopy reveals a range of complex source behavior. The variable He i companion wind emission lines can dominate broadband photometry, especially in red filters or near minimum brightness, and the wind flux should complete companion evaporation in a spin-down time. The heated companion face also undergoes dramatic flares, reaching ˜40,000 K over ˜20% of the star; this is likely powered by a magnetic field generated in the companion. The companion center-of-light radial velocity is now well measured with {{K}CoL}=615.4+/- 5.1 km s-1. We detect non-sinusoidal velocity components due to the heated face flux distribution. Using our spectra to excise flares and wind lines, we generate substantially improved light curves for companion continuum fitting. We show that the inferred inclination and neutron star mass, however, remain sensitive to the poorly constrained heating pattern. The neutron star’s mass, {{M}NS}, is likely less than the direct heating value and could range as low as 1.8 M⊙ for extreme equatorial heating concentration. While we cannot yet pin down {{M}NS}, our data imply that an intrabinary shock reprocesses the pulsar emission and heats the companion. Improved spectra and, especially, models that include such shock heating are needed for precise parameter measurement.

  17. Characterization of porcine skin as a model for human skin studies using infrared spectroscopic imaging.

    PubMed

    Kong, Rong; Bhargava, Rohit

    2011-06-07

    Porcine skin is often considered a substitute for human skin based on morphological and functional data, for example, for transdermal drug diffusion studies. A chemical, structural and temporal characterization of porcine skin in comparison to human skin is not available but will likely improve our understanding of this porcine skin model. Here, we employ Fourier transform infrared (FT-IR) spectroscopic imaging to holistically measure chemical species as well as spatial structure as a function of time to characterize porcine skin as a model for human skin. Porcine skin was found to resemble human skin spectroscopically and differences are elucidated. Cryo-prepared fresh porcine skin samples for spectroscopic imaging were found to be stable over time and small variations are observed. Hence, we extended characterization to the use of this model for dynamic processes. In particular, the capacity and stability of this model in transdermal diffusion is examined. The results indicate that porcine skin is likely to be an attractive tool for studying diffusion dynamics of materials in human skin.

  18. Spectroscopic Studies of Doping and Charge Transfer in Single Walled Carbon Nanotubes and Lead Sulfide Quantum Dots

    NASA Astrophysics Data System (ADS)

    Haugen, Neale O.

    The use of single wall carbon nanotubes (SW-CNTs) in solar photovoltaic (PV) devices is a relatively new, but quickly growing field. SW-CNTs have found application as transparent front contacts, and high work function back contacts in thin film solar PV. For the utility of SW-CNTs to be fully realized, however, controllable and stable doping as well as long term protection from doping must be achieved. Spectroscopic techniques facilitate detailed investigations of the intrinsic and variable properties of semiconductor materials without the issues of contact deposition and the possibility of sample contamination. Detailed spectroscopic analysis of the doping induced changes in the optical properties of SW-CNTs has revealed normally hidden excited state transitions in large diameter single walled carbon nanotubes for the first time. Spectroscopic monitoring of the degree of doping in SW-CNTs made possible studies of the dopant complex desorption and readsorption energies and kinetics. The long term protection from doping of SW-CNTs exposed to ambient laboratory conditions was achieved as a result of the more detailed understanding of the doping processes and mechanisms yielded by these spectroscopic studies. The application of SW-CNTs to other roles in solar PV devices was another goal of this research. Efficient collection of photogenerated charge carriers in semiconductor quantum dot (QD) based solar photovoltaic devices has been limited primarily by the poor transport properties and high density of recombination sites in the QD films. Coupling semiconductor QDs to nanomaterials with better transport properties is one potential solution to the poor transport within the QD films. This portion of the work investigated the possibility of charge transfer occurring in nano-heterostructures (NHSs) of PbS QDs and SW-CNTs produced through spontaneous self-assembly in solution. Electronic coupling in the form of charge transfer from the QDs to the SW-CNTs is unambiguously

  19. Coding Major Fields of Study.

    ERIC Educational Resources Information Center

    Bobbitt, L. G.; Carroll, C. D.

    The National Center for Education Statistics conducts surveys which require the coding of the respondent's major field of study. This paper presents a new system for the coding of major field of study. It operates on-line i a Computer Assisted Telephone Interview (CATI) environment and allows conversational checks to verify coding directly from…

  20. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes.

    PubMed

    Adeniyi, Adebayo A; Ajibade, Peter A

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  1. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes

    NASA Astrophysics Data System (ADS)

    Adeniyi, Adebayo A.; Ajibade, Peter A.

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  2. AB Initio Study of the Structure and Spectroscopic Properties of Halogenated Thioperoxy Radicals

    NASA Technical Reports Server (NTRS)

    Munoz, Luis A.; Binning, R. C., Jr.; Weiner, Brad R.; Ishikawa, Yasuyuki

    1997-01-01

    Thioperoxy (XSO or XOS) radicals exist in a variety of chemical environments, and they have as a consequence drawn some interest. HSO, an important species in the chemistry of the troposphere, has been examined both experimentally. The halogenated (X = F, Cl or Br) peroxy species and isovalent thioperoxy species have been studied less, but they too are potentially interesting because oxidized sulfur species and halogen sources are present in the atmosphere. Learning the fate of XSO and XOS radicals is important to understanding the atmospheric oxidation chemistry of sulfur compounds. Of these, FSO and ClSO are particularly interesting because they have been directly detected spectroscopically. Recent studies in our laboratory on the photochemistry of thionyl halides (X2SO; where X = F or Cl) have suggested new ways to generate XSO species. The laser-induced photodissociation of thionyl fluoride, F2SO, at 193 nm and thionyl chloride, ClSO, at 248 nm is characterized by a radical mechanism, X2SO -> XSO + X. The structure of FSO has been characterized experimentally by Endo et cd. employing microwave spectroscopy. Using the unrestricted Hartree-Fock (UHF) self-consistent field (SCF) method, Sakai and Morokuma computed the electronic structure of the ground (sup 2)A" and the first excited (sup 2)A' states of FSO. Electron correlation was not taken into account in their study. In a laser photodissociation experiment, Huber et al. identified ClSO mass spectromctrically. ClSO has also been detected in low temperature matrices by EPR and in the gas phase by far IR laser magnetic resonance. Although the structure of FSO is known in detail, the only study, experimental or theoretical, of CISO has been an ab initio HFSCF study by Hinchliffe. Electron correlation corrections were also excluded from this study. In order to better understand the isomerization and dissociation dynamics of the radical species, we have performed ab initio correlated studies of the potential energy

  3. Micron-thick spectroscopic cells for studying the Paschen-Back regime on the hyperfine structure of cesium atoms

    SciTech Connect

    Sargsyan, A.; Glushko, B.; Sarkisyan, D. E-mail: davsark@yahoo.com

    2015-04-15

    It is shown that the use of spectroscopic cells of micron thickness (L = 10–50 μm) allows one to effectively study the behavior of individual levels of the Cs D{sub 2} line in strong magnetic fields up to 9 kG. In particular, the absorption spectrum of Cs excited by circularly polarized light in fields above 8 kG consists of two fully separated groups, each containing eight atomic transitions. The intensities of atomic transitions and their frequency slopes (vs. magnetic field) in each group are almost the same. The physical explanation for the observed features is given; in particular, it is shown that one of the 54 possible atomic transitions in moderate magnetic fields (denoted F{sub g} = 4, m{sub F} = 4 → F{sub e} = 5, m{sub F} = 5) has unique characteristics that make it possible to predict the intensities and frequency slopes of seven atomic transitions in the same group. Practical applications of devices based on micrometric-thin cells in strong magnetic fields are considered.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  6. Synthesis, structural and spectroscopic studies of two new benzimidazole derivatives: A comparative study

    NASA Astrophysics Data System (ADS)

    Saral, Hasan; Özdamar, Özgür; Uçar, İbrahim

    2017-02-01

    In the present work, structural and spectroscopic studies on 1-Methyl-2-(2‧-hydroxy-4‧-chlorophenyl)benzimidazole (1) and 1-Methyl-2-(2‧-hydroxy-4‧-methoxyphenyl)benzimidazole (2), have been carried out extensively by X-ray diffraction, HRMS, UV-Vis, FT-IR and 1H and 13C NMR spectroscopy. The crystal structure of both compounds is stabilized by Osbnd H⋯N hydrogen bond and π-π interactions. Contrary to compound 1, the skeleton of compound 2 is considerably deviated from the planarity probably caused by intermolecular hydrogen bonding. The experimental results were compared to the theoretical ones, obtained at DFT level. Ground state geometry, electronic structure, vibrational and NMR spectra have been performed using the B3LYP functional with the 6-31 G(d,p) basis set. It was observed that the bond distances and angles in the both compounds were in good with those of the experiment. The energetic behaviors of the both compounds in methanol solvent were examined using by time-dependent DFT (TD-DFT) method by applying the polarizable continuum model (PCM). Isotropic chemical shifts (13C and 1H NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. The HOMO and LUMO analyses were used to elucidate information regarding charge transfer within the molecule.

  7. Ab initio molecular orbital and infrared spectroscopic study of the conformation of secondary amides: derivatives of formanilide, acetanilide and benzylamides

    NASA Astrophysics Data System (ADS)

    Ilieva, S.; Hadjieva, B.; Galabov, B.

    1999-09-01

    Ab initio molecular orbital calculations at HF/4-31G level and infrared spectroscopic data for the frequencies are applied to analyse the grouping in a series model aromatic secondary amides: formanilide; acetanilide; o-methylacetanilide; 2,6-dimethylformanilide, 2,6-dimethylacetanilide; N-benzylacetamide and N-benzylformamide. The theoretical and experimental data obtained show that the conformational state of the molecules studied is determined by the fine balance of several intramolecular factors: resonance effect between the amide group and the aromatic ring, steric interaction between various substituents around the -NH-CO- grouping in the aromatic ring, conjugation between the carbonyl bond and the nitrogen lone pair as well as direct field influences inside the amide group.

  8. Neutron spectroscopic study of crystalline electric field excitations in stoichiometric and lightly stuffed Yb2Ti2O7

    SciTech Connect

    Gaudet, J.; Maharaj, D. D.; Sala, G.; Kermarrec, E.; Ross, K. A.; Dabkowska, H. A.; Kolesnikov, A. I.; Granroth, G. E.; Gaulin, B. D.

    2015-10-27

    Time-of-flight neutron spectroscopy has been used to determine the crystalline electric field Hamiltonian, eigenvalues and eigenvectors appropriate to the J=7/2 Yb3+ ion in the candidate quantum spin ice pyrochlore magnet Yb2Ti2O7. The precise ground state of this exotic, geometrically frustrated magnet is known to be sensitive to weak disorder associated with the growth of single crystals from the melt. Such materials display weak “stuffing,” wherein a small proportion, approximately 2%, of the nonmagnetic Ti4+ sites are occupied by excess Yb3+. We have carried out neutron spectroscopic measurements on a stoichiometric powder sample of Yb2Ti2O7, as well as a crushed single crystal with weak stuffing and an approximate composition of Yb2+xTi2–xO7+y with x = 0.046. All samples display three crystalline electric field transitions out of the ground state, and the ground state doublet itself is identified as primarily composed of mJ = ±1/2, as expected. However, stuffing at low temperatures in Yb2+xTi2–xO7+y induces a similar finite crystalline electric field lifetime as is induced in stoichiometric Yb2Ti2O7 by elevated temperature. In conclusion, an extended strain field exists about each local “stuffed” site, which produces a distribution of random crystalline electric field environments in the lightly stuffed Yb2+xTi2–xO7+y, in addition to producing a small fraction of Yb ions in defective environments with grossly different crystalline electric field eigenvalues and eigenvectors.

  9. Spectroscopic observation of fluctuation-induced dynamo in the edge of the reversed-field pinch.

    PubMed

    Fontana, P W; Den Hartog, D J; Fiksel, G; Prager, S C

    2000-07-17

    The fluctuation-induced dynamo has been investigated by direct measurement of v and b in the edge of a reversed-field pinch and is found to be significant in balancing Ohm's law. The velocity fluctuations producing the dynamo emf have poloidal mode number m = 0, consistent with MHD calculations and in contrast with the core m = 1 dynamo. The velocity fluctuations exhibit the parity relative to their resonant surface predicted by linear MHD theory.

  10. Fourier transform Raman spectroscopic studies of a novel wood pulp bleaching system

    NASA Astrophysics Data System (ADS)

    Weinstock, Ira A.; Atalla, Rajai H.; Agarwal, Umesh P.; Minor, James L.; Petty, Chris

    1993-06-01

    The use of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy for the study of lignocellulosic materials is discussed. An application utilizing NIR FT-Raman spectroscopy to study a novel chlorine-free process for the bleaching of wood pulps is presented in detail. The new process, still under development, entails the oxidation of residual lignin in wood pulps by vanadium-substituted polyoxometalates, and reoxidation of the reduced polyoxometalates by chlorine-free oxidants such as air, dioxygen, peroxides or ozone. Results from FT-Raman measurements of polyoxometalate-treated pulps are compared with those from chemical, spectroscopic and optical techniques commonly used in the pulp and paper industry.

  11. Spectroscopic study of sub-barrier quasi-elastic nuclear reactions

    SciTech Connect

    Pass, C.N.; Evans, P.M.; Smith, A.E.; Stuttge, L.; Betts, R.R.; Lilley, J.S.; Connell, K.A.; Simpson, J.; Smith, J.R.; James, A.N.

    1988-01-01

    The technique developed in this paper is particularly well suited to the detailed spectroscopic study of low energy quasi-elastic nuclear reactions and by overcoming the limitations of conventional procedure, the prospect of detailed studies of inclusive reaction mechanism may be realised. With only limited statistics we find evidence for strong multistep character in the transfer of a single nucleon from spherical vibrational target to spherical projectile nuclei. The suggestive measurements reported here may be made definitive through extended runs based on this technique and experiments planned for the future offer the real prospect of developing a quantified interpretation of the reaction process. 9 refs. 5 figs.

  12. Study of spectroscopic and thermal characteristics of nonlinear optical molecular crystals based on 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Pavlovetc, I. M.; Fokina, M. I.

    2016-08-01

    The paper presents the results of study of spectroscopic and thermal characteristics of molecular co-crystals: 2-aminopyridine-4-nitrophenol-4-mtrophenolate (2AP4N) and 2,6- diaminopyridine-4-nitrophenol-4nitrophenolate (26DAP4N). Crystals were successfully grown by slow evaporation technique. Optical transparency in the region of 190-1100 was found to be suitable for applications with cut off wavelengths 420 and 430 nm respectively. Thermogravimetric and differential thermal analysis show good quality and thermal stability for studied crystals. Kurtz and Perry powder technique proves that the crystals are acentric and have significant nonlinear optical response.

  13. High-Resolution Photoionization, Photoelectron and Photodissociation Studies. Determination of Accurate Energetic and Spectroscopic Database for Combustion Radicals and Molecules

    SciTech Connect

    Ng, Cheuk-Yiu

    2016-04-25

    The main goal of this research program was to obtain accurate thermochemical and spectroscopic data, such as ionization energies (IEs), 0 K bond dissociation energies, 0 K heats of formation, and spectroscopic constants for radicals and molecules and their ions of relevance to combustion chemistry. Two unique, generally applicable vacuum ultraviolet (VUV) laser photoion-photoelectron apparatuses have been developed in our group, which have used for high-resolution photoionization, photoelectron, and photodissociation studies for many small molecules of combustion relevance.

  14. Task 1.11 - Spectroscopic field screening of hazardous waste and toxic spills. Semi-annual report, January 1--June 30, 1995

    SciTech Connect

    Gristanti, A.A.

    1995-12-31

    Techniques for the field characterization of soil contamination due to spillage of hazardous waste or toxic chemicals are time-consuming and expensive. Thus, more economical, less time-intensive methods are needed to facilitate rapid field screening of contaminated sites. In situ detection of toxic chemicals in soil offers both time and cost advantages for field screening with additional application to real-time site monitoring. Fourier-transform infrared (FT-IR) spectroscopy coupled with evanescent mode fiber-optic sensors has been demonstrated as a means to remotely detect and classify petroleum products in water using mid-infrared (MIR) optical fibers. This work demonstrated that a fiber-optic evanescent field absorbance sensor (EFAS) could be used to classify petroleum contamination into categories such as crude oil, kerosene, No. 2 fuel and residual distillates using the MIR spectral range. The overall objective of this project is to study the feasibility of using an EFAS FT-IR spectroscopic sensor coupled with cone penetrometry as a field screening method. The Fourier transform infrared cone penetrometry method (FT-IR-CPT) will be developed by building on the work cited above. The specific objectives of this project are: design an accessory for use with FT-IR that interfaces the spectrometer to a cone penetrometer; characterize the response of the FT-IR accessory to selected hydrocarbons in a laboratory-simulated field environment; and determine the ability of the FT-IR-CPT instrument to measure hydrocarbon contamination in soil by direct comparison with a reference method to quantify hydrocarbons from the same soil.

  15. Spectroscopic Observation of Fluctuation-Induced Dynamo in the Edge of the Reversed-Field Pinch

    SciTech Connect

    Fontana, P. W.; Den Hartog, D. J.; Fiksel, G.; Prager, S. C.

    2000-07-17

    The fluctuation-induced dynamo has been investigated by direct measurement of v(tilde sign) and b(tilde sign) in the edge of a reversed-field pinch and is found to be significant in balancing Ohm's law. The velocity fluctuations producing the dynamo emf have poloidal mode number m=0 , consistent with MHD calculations and in contrast with the core m=1 dynamo. The velocity fluctuations exhibit the parity relative to their resonant surface predicted by linear MHD theory. (c) 2000 The American Physical Society.

  16. Static magnetic fields: animal studies.

    PubMed

    Saunders, Richard

    2005-01-01

    Various experimental studies carried out over the last 30-40 years have examined the effects of the chronic or acute exposure of laboratory animals to static magnetic fields. Many of the earlier studies have been adequately reviewed elsewhere; few adverse effects were identified. This review focuses on studies carried out more recently, mostly those using vertebrates, particularly mammals. Four main areas of investigation have been covered, viz., nervous system and behavioural studies, cardiovascular system responses, reproduction and development, and genotoxicity and cancer. Work on the role of the natural geomagnetic field in animal orientation and migration has been omitted. Generally, the acute responses found during exposure to static fields above about 4 T are consistent with those found in volunteer studies, namely the induction of flow potentials around the heart and the development of aversive/avoidance behaviour resulting from body movement in such fields. No consistently demonstrable effects of exposure to fields of approximately 1T and above have been seen on other behavioural or cardiovascular endpoints. In addition, no adverse effects of such fields on reproduction and development or on the growth and development of tumours have been firmly established. Overall, however, far too few animal studies have been carried out to reach any firm conclusions.

  17. Synthesis, spectroscopic characterizations, crystal structures and DFT studies of nalidixic acid carbonyl hydrazones derivatives

    NASA Astrophysics Data System (ADS)

    Bergamini, F. R. G.; Ribeiro, M. A.; Lancellotti, M.; Machado, D.; Miranda, P. C. M. L.; Cuin, A.; Formiga, A. L. B.; Corbi, P. P.

    2016-09-01

    This article describes the synthesis and characterization of the 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazide (hzd) and six carbonyl hydrazones derivatives of the nalidixic with 1H-pyrrol-2-ylmethylidene (hpyrr), 1H-imidazol-2-ylmethylidene (h2imi), pyridin-2-ylmethylidene (h2py), pyridin-3-ylmethylidene (h3py), pyridin-4-ylmethylidene(h4py) and (2-hydroxyphenyl)methylidene (hsali). The carbonyl hydrazones were characterized by elemental and ESI-QTOF-MS analyses, IR and detailed NMR spectroscopic measurements. The 2D NMR experiments allowed the unambiguous assignment of the hydrogen, carbon and nitrogen atoms, which have not been reported for nalidixic acid carbonyl hydrazone derivatives so far. Crystal structures of hzd and the new carbonyl hydrazones h2imi, hpyrr and h3py were determined by X-ray diffraction studies. Although the synthesis of hzd was reported decades ago, the hzd crystal structure have not been reported yet. Geometric optimizations of all the characterized structures were performed with the aid of DFT studies. Despite the fact that the hydrazones with 2-pyridine carboxylic acid (h2py) and salicyl aldehyde (hsali) were already reported by literature, a detailed spectroscopic study followed by DFT studies are also reported for such compounds in this manuscript. Antimicrobial studies of the compounds are also presented.

  18. A spectroscopic study of the radial velocity variations and accretion disks found in four dwarf novae

    NASA Astrophysics Data System (ADS)

    Stover, R. J.

    Time resolved spectroscopic observations of the four dwarf novae SS Cyg, EM Cyg, U Gem, and RU Peg are presented. Although these systems were studied previously, all of the spectroscopic studies were done photographically. A linear response, digital detector is employed. Analytic techniques to the study of the radial velocity variations and emission line profiles found in dwarf novae are applied. In the study of SS Cyg cross-correlation techniques were used for the first time to measure the radial velocity variations of the secondary star absorption lines. In the study of U Gem, analysis of the accretion disk emission lines showed that the motion of the material in the disk cannot be described accurately by orbits defined within the three-body approximation. The observations of EM Cyg reveal an unstable accretion disk, with emission lines that vary erratically on timescales of minutes to days. New measurements of the radial velocity variations of the emission and absorption lines found in the spectrum of RU Peg agree with previous measurements but have a higher accuracy.

  19. Thermal Physical, and Infrared Spectroscopic Studies on Glasses Prepared by Microwave Route

    SciTech Connect

    Jagadeesha, N.; Gowda, V. C. Veeranna; Chakradhar, R. P. S.; Reddy, C. Narayana

    2011-07-15

    This paper describes thermal, physical and spectroscopic properties of glasses prepared by a novel micro wave method. These studies exhibited a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The scheme of modification of borate and vanadate groups is controlled by Sanderson's electronegativity principle. Analysis of density and glass transition temperatures suggests the presence of characteristic four coordinated borate and diboro - vanadate groups in these glasses. The presence of [BO{sub 4/2}]{sup -} and [B{sub 2}V{sub 2}O{sub 9}]{sup 2-}) groups are confirmed by Infrared Spectroscopy of investigated glasses.

  20. On-line separator for {gamma}-spectroscopic studies at FLNR JINR

    SciTech Connect

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Kabachenko, A. P.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.; Dorvaux, O.; Hauschild, K.; Korichi, A.; Lopez-Martens, A.

    2007-05-22

    A JINR - IN2P3 collaboration project named 'GABRIELA' aimed at the nuclear spectroscopy of transfermium elements using the recoil separator VASSILISSA was launched in 2004 at JINR in Dubna. In the close future the FLNR cyclotron U400M will go through a major upgrade with the goal to deliver heavy ion beams at the energy close to the Coulomb barrier in a new experimental area. Here we report about R and D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized accelerator and which will allow to realize new possibilities of the GABRIELA project.

  1. On-line separator for γ-spectroscopic studies at FLNR JINR

    NASA Astrophysics Data System (ADS)

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Dorvaux, O.; Hauschild, K.; Kabachenko, A. P.; Korichi, A.; Lopez-Martens, A.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.

    2007-05-01

    A JINR — IN2P3 collaboration project named "GABRIELA" aimed at the nuclear spectroscopy of transfermium elements using the recoil separator VASSILISSA was launched in 2004 at JINR in Dubna. In the close future the FLNR cyclotron U400M will go through a major upgrade with the goal to deliver heavy ion beams at the energy close to the Coulomb barrier in a new experimental area. Here we report about R&D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized accelerator and which will allow to realize new possibilities of the GABRIELA project.

  2. HeI photoelectron spectroscopic studies on the electronic structure of alkyl nitrosamines

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Qian, Ximei; Li, Chunhui; Qiao, Chunhua; Wang, Dianxun

    1997-10-01

    HeI photoelectron spectroscopic (PES) studies on the electronic structure of alkyl nitrosamines R 2N 2O (R = CH 3-, CH 3CH 2-, and CH 3CH 2CH 2-) are reported. The assignment of the PES bands for this series of compounds has been made with the aid of the band shapes, the band intensity and ab initio SCF MO calculations based on the 631 ∗ G basis sets. Both PES experiment and the ab initio SCF MO calculations show that the detoxification ability of nitrosamine with longer alkyl chain is stronger.

  3. Dielectric properties of WS2-coated multiwalled carbon nanotubes studied by energy-loss spectroscopic profiling

    NASA Astrophysics Data System (ADS)

    Stolojan, Vlad; Silva, S. R. P.; Goringe, Michael J.; Whitby, R. L. D.; Hsu, Wang K.; Walton, D. R. M.; Kroto, Harold W.

    2005-02-01

    We investigate experimentally the electronic properties of the coating for multiwalled carbon nanotubes covered in tungsten disulfide (WS2) of various thicknesses. Coatings of thicknesses between 2 and 8 monolayers (ML) are analyzed using energy-loss spectroscopic profiling (ELSP), by studying the variations in the plasmon excitations across the coated nanotube, as a function of the coating thickness. We find a change in the ELSP for coatings above 5 ML thickness, which we interpret in terms of a change in its dielectric properties.

  4. Spectroscopic Properties of Selected Narrow Emission Line Galaxies from the COSMOS Field

    NASA Astrophysics Data System (ADS)

    Colon, Amy M.; Carroll, P.; Roberts, R.; Wong, N.; Liu, C.

    2007-12-01

    We present properties of seven blue narrow emission line galaxies (NELGs) in the redshift range 0.25 < z < 0.73, initially selected as QSO candidates in the COSMOS 2-degree survey field. These galaxies have been selected for the high signal-to-noise of their spectra, as indicated by the presence of the emission line [NeIII] 3869 Angstroms. Emission line diagnostics are used to measure metallicities and star formation rates, and to test the presence of AGN. Hubble ACS images are used to measure their surface brightness distributions and quantitative morphologies. Preliminary results indicate that these objects are forming stars at a rate of 4 to 20 solar masses per year; and their metallicity appears not to vary with the galaxy's concentration index which ranges 0.42 to 0.63.

  5. Quartic force field-derived vibrational frequencies and spectroscopic constants for the isomeric pair SNO and OSN and isotopologues

    SciTech Connect

    Fortenberry, Ryan C.; Francisco, Joseph S.

    2015-08-28

    The SNO and OSN radical isomers are likely to be of significance in atmospheric and astrochemistry, but very little is known about their gas phase spectroscopic properties. State-of-the-art ab initio composite quartic force fields are employed to analyze the rovibrational features for both systems. Comparison to condensed-phase experimental data for SNO has shown that the 1566.4 cm{sup −1} ν{sub 1} N–O stretch is indeed exceptionally bright and likely located in this vicinity for subsequent gas phase experimental analysis. The OSN ν{sub 1} at 1209.4 cm{sup −1} is better described as the antisymmetric stretch in this molecule and is also quite bright. The full vibrational, rotational, and rovibrational data are provided for SNO and OSN and their single {sup 15}N, {sup 18}O, and {sup 34}S isotopic substitutions in order to give a more complete picture as to the chemical physics of these molecules.

  6. VizieR Online Data Catalog: RIOTS4: spectroscopic survey of SMC field OB stars (Lamb+, 2016)

    NASA Astrophysics Data System (ADS)

    Lamb, J. B.; Oey, M. S.; Segura-Cox, D. M.; Graus, A. S.; Kiminki, D. C.; Golden-Marx, J. B.; Parker, J. W.

    2016-04-01

    Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC (RIOTS4) targets a spatially complete sample of 374 uniformly selected candidate field OB stars in the SMC. Our targets are identified by Oey et al. (2004, J/AJ/127/1632). We observed the RIOTS4 survey targets over a five-year period from 2006 September to 2011 October using spectrographs on the Magellan telescopes at Las Campanas Observatory. The majority of our observations were obtained with the Inamori-Magellan Areal Camera and Spectrograph (IMACS) in the f/4 multi-slit mode on the Magellan Baade telescope (slit widths of either 0.7" or 1.0", yielding spectral resolutions of R~3700 and R~2600, respectively). With IMACS f/4 out of commission during our 2011 observations, we also operated IMACS in f/2 mode (we used either a 0.5" or 0.7" slit width, which yield spectral resolutions of R~1000 and R~1300, respectively). The remaining targets were observed using the Magellan Inamori Kyocera Echelle (MIKE) Spectrograph on the Magellan Clay telescope (R~28000). All MIKE observations occurred in 2010 November. (2 data files).

  7. A Spectroscopic and Photometric Survey of Stars in the Field of L1457: A New Distance Determination

    NASA Astrophysics Data System (ADS)

    Andersson, B.-G.; Idzi, R.; Uomoto, Alan; Wannier, P. G.; Chen, B.; Jorgensen, A. M.

    2002-10-01

    We present a spectroscopic and photometric survey of a sample of field stars in the region of the molecular cloud L1457. High-quality coudé feed spectra, together with five-band photometry in the Sloan Digital Sky Survey system and near-infrared archival data from the Two Micron All Sky Survey, are used to derive color excesses and distances for the stars. Based on these data, a new distance estimate of 360+/-30 pc is derived for the cloud, supporting recent results by K. L. Luhman. The data further indicate that the north-south velocity gradient seen in the millimeter-wave CO data is mirrored in a distance gradient, with the northern part of the cloud being closer to us. A second, less opaque, layer of extinction is detected at ~80 pc. This distance is consistent with the earlier distance estimates to the cloud, based on Na I absorption. We identify this layer with the wall of the hot Local Bubble. Hence, the dense cloud is not, as previously thought, associated with the Local Bubble.

  8. FTIR spectroscopic study of the complex formation between H(+) and DMSO in Nafion.

    PubMed

    Karelin, A I; Kayumov, R R; Sanginov, E A; Dobrovolsky, Yu A

    2017-05-05

    Nafion membranes plasticized with dimethyl sulfoxide (DMSO) have been examined at room temperature using the vacuum ATR - FTIR spectroscopic technique in the range 50-4000cm(-1). The amount of the plasticizer corresponds to the molecular ratio n=DMSO/H(+)=1.2, 2.3, 4.8, 7.0, 9.7 and 13.3. The medium intensity band with two maxima at 780 and 853cm(-1) have been assigned to the ν(SO) stretching vibrations of the H(+)(DMSO)2 complex. The possible reason of ν(SO) splitting is symmetry decrease of hydrogen bond under the influence of the anion group SO3(-) electric field. Whereas the mutual association of free DMSO molecules in Nafion leads to appearance of weak band at 86cm(-1) assigned to the dipole-dipole interactions.

  9. Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies

    NASA Astrophysics Data System (ADS)

    Jing, Mingyang; Song, Wei; Liu, Rutao

    2016-07-01

    Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298 K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper.

  10. Majorana Neutrino Masses by Spectroscopic Studies of Double Beta Decays and Moon

    NASA Astrophysics Data System (ADS)

    Ejiri, Hiroyasu

    This is a brief review of spectroscopic studies of neutrino-less double beta decays (0νββ) and the MOON (Mo Observatory Of Neutrinos) project. It aims at studying the Majorana nature of neutrinos and the mass spectrum by spectroscopic studies of 0νββ with ν-mass sensitivity of ≈ 30 meV. The solid scintillator option of the MOON detector is a super ensemble of multi-layer modules, each being composed by a scintillator plate and two tracking detector planes. Thin ββ source films are interleaved between the detector planes. High localization of the two β tracks enables one to select true signals and reject BG ones by spatial and time correlation analyses. MOON with detector ≠ ββ source is used for studying 0νββ decays from 100Mo, 82Se and other ββ isotopes with large nuclear sensitivity (large Qββ). Real-time exclusive measurements of low energy solar neutrinos can also be made by observing inverse β rays from solar-ν captures of 100Mo in delayed coincidence with the subsequent β decay of 100Tc.

  11. The Distance to the Massive Galactic Cluster Westerlund 2 from a Spectroscopic and HST Photometric Study

    NASA Astrophysics Data System (ADS)

    Vargas Álvarez, Carlos A.; Kobulnicky, Henry A.; Bradley, David R.; Kannappan, Sheila J.; Norris, Mark A.; Cool, Richard J.; Miller, Brendan P.

    2013-05-01

    We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters RV and AV for O-type stars in Wd2. We find average values langRV rang = 3.77 ± 0.09 and langAV rang = 6.51 ± 0.38 mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance langdrang = 4.16 ± 0.07 (random) +0.26 (systematic) kpc. The cluster's age remains poorly constrained, with an upper limit of 3 Myr. Finally, we report evidence of a faint mid-IR polycyclic aromatic hydrocarbon ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  12. THE DISTANCE TO THE MASSIVE GALACTIC CLUSTER WESTERLUND 2 FROM A SPECTROSCOPIC AND HST PHOTOMETRIC STUDY

    SciTech Connect

    Vargas Alvarez, Carlos A.; Kobulnicky, Henry A.; Bradley, David R.; Kannappan, Sheila J.; Norris, Mark A.; Cool, Richard J.; Miller, Brendan P. E-mail: chipk@uwyo.edu E-mail: sheila@physics.unc.edu E-mail: rcool@obs.carnegiescience.edu

    2013-05-15

    We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters R{sub V} and A{sub V} for O-type stars in Wd2. We find average values (R{sub V} ) = 3.77 {+-} 0.09 and (A{sub V} ) = 6.51 {+-} 0.38 mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance (d) = 4.16 {+-} 0.07 (random) +0.26 (systematic) kpc. The cluster's age remains poorly constrained, with an upper limit of 3 Myr. Finally, we report evidence of a faint mid-IR polycyclic aromatic hydrocarbon ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2.

  13. 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.

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

    PubMed

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

    2016-02-05

    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.

  15. Intensity Modulated Radiation Treatment of Prostate Cancer Guided by High Field MR Spectroscopic Imaging

    DTIC Science & Technology

    2005-05-01

    and demonstrate the feasibility of concurrent dose escalation to intraprostatic lesion(s) through a set of phantom studies and at least two previously...TPS) method 12" 3 to deal with the registration of endorectal MRI/MRSI and verified the accuracy of the registration by phantom and patient studies...hypothetical phantom case and a prostate case and comparison of the results with that obtained using conventional inverse planning technique with structure

  16. Development of optical spectroscopic instruments and application to field measurements of marine trace gases

    NASA Astrophysics Data System (ADS)

    Coburn, Sean Christopher

    Halogens (X = Cl, Br, I) and organic carbon are relevant to the oxidative capacity of the atmosphere, are linked to atmospheric sulfur and nitrogen cycles, modify aerosols, and oxidize atmospheric mercury. The abundance of halogen radical species in the atmosphere is very low, but even concentrations of parts per trillion (1 ppt = 10-12 volume mixing ratio) or parts per quadrillion (1 ppq = 10-15 volume mixing ratio) are relevant for the aforementioned processes. Halogen radicals can be traced through measurements of halogen oxides (XO, where X = Cl, Br, I), that are ~1-10 times more abundant. However, measurements of halogen oxides are sparse, partly due to the lack of analytical techniques that enable their routine detection. In Chapters II-IV, I describe the development of a research grade Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument to measure bromine monoxide (BrO) and iodine monoxide (IO) routinely in the troposphere. I present autonomous measurements of BrO and IO in Pensacola, Florida that maximize sensitivity towards the detection of BrO in the free troposphere (altitudes >2km) from ground. The measurements are then coupled to a box-model to assess their impact on the oxidation of mercury in the atmosphere. Chapter V describes the Fast Light-Emitting-Diode Cavity-Enhanced DOAS (Fast LED-CE-DOAS) instrument and first measurements of glyoxal diurnal cycles and Eddy Covariance (EC) fluxes of glyoxal in the marine atmosphere. Glyoxal is the smallest alpha-dicarbonyl and a useful tracer molecule for fast photochemistry of hydrocarbons over oceans. The unique physical and chemical properties of glyoxal pose challenges in explaining this soluble gas over the remote ocean, and recent measurements over the open ocean currently remain unexplained by models. Results from a first cruise deployment over the tropical Pacific Ocean (TORERO field campaign) are presented.

  17. Development of a polarization resolved spectroscopic diagnostic for measurements of the magnetic field in the Caltech coaxial magnetized plasma jet experiment

    NASA Astrophysics Data System (ADS)

    Shikama, Taiichi; Bellan, Paul M.

    2011-11-01

    Measurements of the magnetic field strength in current-carrying magnetically confined plasmas are necessary for understanding the underlying physics governing the dynamical behavior. Such a measurement would be particularly useful in the Caltech coaxial magnetized plasma gun, an experiment used for fundamental studies relevant to spheromak formation, astrophysical jet formation/propagation, solar coronal physics, and the general behavior of twisted magnetic flux tubes that intercept a boundary. In order to measure the field strength in the Caltech experiment, a non-perturbing spectroscopic method is being implemented to observe the Zeeman splitting in the emission spectra. The method is based on polarization-resolving spectroscopy of the Zeeman-split σ components, a technique previously used in both solar and laboratory plasmas. We have designed and constructed an optical system that can simultaneously detect left- and right-circularly polarized emission with both high throughput and small extinction ratio. The system will be used on the 489.5 nm NII line, chosen because of its simple Zeeman structure and minimal Stark broadening.

  18. Laser spectroscopic and theoretical studies of the structures and encapsulation motifs of functional molecules

    SciTech Connect

    Ebata, Takayuki; Kusaka, Ryoji; Xantheas, Sotiris S.

    2015-01-22

    Extensive laser spectroscopic and theoretical studies have been recently carried out with the aim to reveal the structure and dynamics of encapsulation complexes in the gas phase. The characteristics of the encapsulation complexes are governed by the fact that (i) most of the host molecules are flexible and (ii) the complexes form high dimensional structures by using weak non-covalent interactions. These characteristics result in the possibility of the coexistence of many conformers in close energetic proximity. The combination of supersonic jet/laser spectroscopy and high level quantum chemical calculations is essential in tackling these challenging problems. In this report we describe our recent studies on the structures and dynamics of the encapsulation complexes formed by calix[4]arene (C4A), dibenzo-18-crown-6-ether (DB18C6), and benzo-18-crown-6-ether (B18C6) 'hosts' interacting with N{sub 2}, acetylene, water, and ammonia 'guest' molecules. The gaseous host-guest complexes are generated under jet-cooled conditions. We apply various laser spectroscopic methods to obtain the conformer- and isomer-specified electronic and IR spectra. The experimental results are complemented with quantum chemical calculations ranging from density functional theory to high level first principles calculations at the MP2 and CCSD(T) levels of theory. We discuss the possible conformations of the bare host molecules, the structural changes they undergo upon complexation, and the key interactions that are responsible in stabilizing the specific complexes.

  19. Laser Spectroscopic and Theoretical Studies of the Structures and Encapsulation Motifs of Functional Molecules

    SciTech Connect

    Ebata, Takayuki; Kusaka, Ryoji; Xantheas, Sotiris S.

    2015-02-01

    Extensive laser spectroscopic and theoretical studies have been recently carried out with the aim to reveal the structure and dynamics of encapsulation complexes in the gas phase. The characteristics of the encapsulation complexes are governed by the fact that (i) most of the host molecules are flexible and (ii) the complexes form high dimensional structures by using weak non-covalent interactions. These characteristics result in the possibility of the coexistence of many conformers in close energetic proximity. The combination of supersonic jet/laser spectroscopy and high level quantum chemical calculations is essential in tackling these challenging problems. In this report we describe our recent studies on the structures and dynamics of the encapsulation complexes formed by calix[4]arene (C4A), dibenzo-18-crown-6-ether (DB18C6), and benzo-18-crown-6-ether (B18C6) "hosts" interacting with N2, acetylene, water, and ammonia "guest" molecules. The gaseous host-guest complexes are generated under jet-cooled conditions. We apply various laser spectroscopic methods to obtain the conformer- and isomer-specified electronic and IR spectra. The experimental results are complemented with quantum chemical calculations ranging from density functional theory to high level first principles calculations at the MP2 and CCSD(T) levels of theory. We discuss the possible conformations of the bare host molecules, the structural changes they undergo upon complexation, and the key interactions that are responsible in stabilizing the specific complexes

  20. Vibrational spectroscopic study of newly developed self-forming lipids and nanovesicles.

    NASA Astrophysics Data System (ADS)

    Bista, Rajan; Bruch, Reinhard

    2009-03-01

    We present the first experimental study of self-forming synthetic nanovesicles, trademarked as QuSomes, using vibrational spectroscopic techniques namely near-infrared (NIR) and laser tweezers Raman spectroscopy. Raman spectra of these new artificial nanovesicles suspended in Phosphate Buffered Saline (PBS) have been obtained by using an inverted confocal laser-tweezers-Raman-microscopy system in the spectral range of 3100 to 500 cm-1. This spectrometer works with an 80 mW diode-pumped solid-state laser, operating at a wavelength of 785 nm in the TEM00 mode. The laser is used both for optical trapping and Raman excitation. Similarly, NIR absorption spectra of these novel nanovesicles have been recorded in the spectral range of 9000-4800 cm-1 by using a new miniaturized micro-mirror spectrometer based on micro-optical-electro-mechanical systems (MOEMS) technology. In this work, we have found that the most prominent bands in the studied spectral region of Raman spectra are dominated by vibrational modes arising from C-C and CH2 bonds. Similarly, NIR spectra are primarily assigned as first and second overtone of C-H stretching mode and second overtone of C=O stretching mode. These spectroscopic techniques have proven to be an excellent tool to establish the fingerprint region revealing the molecular structure and conformation of QuSomes nanoparticles.

  1. Theoretical DFT study on spectroscopic signature and molecular dynamics of neurotransmitter and effect of hydrogen removal

    NASA Astrophysics Data System (ADS)

    Mukherjee, V.; Singh, N. P.; Yadav, R. A.

    2013-04-01

    Vibrational spectroscopic study has been made for the serotonin molecule and its deprotonated form. The Infrared and Raman spectra in optimum geometry of these two molecules are calculated using density functional theorem and the normal modes are assigned using potential energy distributions (PEDs) which are calculated using normal coordinate analysis method. The vibrational frequencies of these two molecules are reported and a comparison has been made. The effect of removal of the hydrogen atom from the serotonin molecule upon its geometry and vibrational frequencies are studied. Electronic structures of these two molecules are also studied using natural bond orbital (NBO) analysis. Theoretical Raman spectrum of serotonin at different exciting laser frequencies and at different temperatures are obtained and the results are discussed. Present study reveals that some wrong assignments had been made for serotonin molecule in earlier study.

  2. Spectroscopic studies of undoped and Mn2+-doped calcium borophosphate phosphor (CaBP) nanopowders

    NASA Astrophysics Data System (ADS)

    Yadav, M. R.; Raja, B. J.; Manjari, V. P.; Avinash, M.; Krishna, C. R.; Ravikumar, R. V. S. S. N.

    2016-02-01

    Undoped and Mn2+-doped Ca6BP5O20 nanopowders (CaBP) have been prepared by modified solid-state synthesis and characterized by spectroscopic investigations like X-ray diffraction (XRD), field emission scanning electron microscope with EDX, optical absorption, electron paramagnetic resonance, photoluminescence and Fourier transform infrared spectroscopy. From powder XRD patterns, the crystal structure is confirmed to be triclinic. Unit cell parameters, average crystal size, strain and dislocation densities have been calculated by using powder XRD data. Field emission scanning electron micrograph with EDX images, taken at different magnifications, shows that the prepared samples contain Ca, B, P, O, Mn species and micrographs exhibit irregular shaped spheres with agglomeration. By using optical absorption and electron paramagnetic resonance data, crystal field, inter-electronic repulsion and spin-Hamiltonian parameters have been evaluated. The site symmetry of Mn2+ ions is ascribed as octahedral sites with ligands. Fourier transform infrared spectra show the specific vibrations of phosphate and inorganic molecules. Photoluminescence spectra of undoped and Mn2+-doped CaBP nanopowders exhibit pale yellow to white emission under the excitation wavelength of 325 nm. The CIE chromaticity coordinates have been also calculated from emission spectrum for undoped and Mn2+-doped CaBP nanopowders.

  3. Intensity Modulated Radiation Treatment of Prostate Cancer Guided by High Field MR Spectroscopic Imaging

    DTIC Science & Technology

    2006-05-01

    through a set of phantom studies and at least two previously treated prostate cases who had undergone CT/MRSI scans. Under the generous support from the...using digital phantoms and patient CT images. The deformable registration algorithm developed in this project was also applied to several other...method is extended to provide the spatial distribution information as well all within a reasonable scan time (17 min). Phantom and in vivo data are

  4. Spectroscopic and structural studies on lactose species in aqueous solution combining the HATR and Raman spectra with SCRF calculations.

    PubMed

    Márquez, María Jimena; Brizuela, Alicia Beatriz; Davies, Lilian; Brandán, Silvia Antonia

    2015-04-30

    In this work, the α and β isomers, the α-lactose monohydrate and dihydrate and the dimeric species of lactose were studied from the spectroscopic point of view in gas and aqueous solution phases combining the infrared, Horizontal Attenuated Total Reflectance (HATR) and Raman spectra with the density functional theory (DFT) calculations. Aqueous saturated solutions of α-lactose monohydrate and solutions at different molar concentrations of α-lactose monohydrate in water were completely characterized by infrared, HATR and Raman spectroscopies. For all the species in solution, the solvent effects were studied using the solvation polarizable continuum (PCM) and solvation (SM) models and, then, their corresponding solvation energies were predicted. The vibrational spectra of those species in aqueous solution were completely assigned by employing the Scaled Quantum Mechanics Force Field (SQMFF) methodology and the self-consistent reaction field (SCRF) calculations. The stabilities of all those species were studied by using the natural bond orbital (NBO), and atoms in molecules (AIM) calculations.

  5. Electron spectroscopic study (ESI, EELS) of Nanoplast-embedded mammalian lung.

    PubMed

    Fehrenbach, H; Richter, J; Schnabel, P A

    1992-06-01

    The potential of Nanoplast melamine resin embedding for the study of mammalian lung parenchyma was examined by means of electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS). Samples were either fixed with glutaraldehyde-paraformaldehyde or glutaraldehyde-tannic acid, or were directly transferred to the embedding medium without prior fixation. Organic dehydrants, as well as fixatives containing heavy metals and stains, were omitted. A very high level of ultrastructural detail of chromatin, ribosomes, mitochondria and plasma membranes was achieved by ESI from the Nanoplast-embedded samples. The most prominent gain in ultrastructural detail was achieved when moving from an energy loss just below the L2,3 edge of phosphorus at 132 eV to an energy loss just beyond this edge. This reflects the prominent P L2,3 edge observed by EELS of Nanoplast-embedded samples in comparison with conventionally processed samples. Thus, taking into account possible sectioning artefacts, excellent heterochromatin images which rely on the phosphorus distribution can be obtained from Nanoplast-embedded samples by computer-assisted analysis of electron spectroscopic images. In this respect glutaraldehyde-paraformaldehyde fixation is preferable to glutaraldehyde-tannic acid fixation because the presence of silicon, revealed by EELS, in tannic-acid-fixed samples may introduce artefacts in phosphorus distribution images obtained by the three-window method because of the close proximity of the L2,3 edges of silicon and phosphorus.

  6. Spectroscopic study of honey from Apis mellifera from different regions in Mexico.

    PubMed

    Frausto-Reyes, C; Casillas-Peñuelas, R; Quintanar-Stephano, J L; Macías-López, E; Bujdud-Pérez, J M; Medina-Ramírez, I

    2017-05-05

    The objective of this study was to analyze by Raman and UV-Vis-NIR Spectroscopic techniques, Mexican honey from Apis Mellífera, using representative samples with different botanic origins (unifloral and multifloral) and diverse climates. Using Raman spectroscopy together with principal components analysis, the results obtained represent the possibility to use them for determination of floral origin of honey, independently of the region of sampling. For this, the effect of heat up the honey was analyzed in relation that it was possible to greatly reduce the fluorescence background in Raman spectra, which allowed the visualization of fructose and glucose peaks. Using UV-Vis-NIR, spectroscopy, a characteristic spectrum profile of transmittance was obtained for each honey type. In addition, to have an objective characterization of color, a CIE Yxy and CIE L*a*b* colorimetric register was realized for each honey type. Applying the principal component analysis and their correlation with chromaticity coordinates allowed classifying the honey samples in one plot as: cutoff wavelength, maximum transmittance, tones and lightness. The results show that it is possible to obtain a spectroscopic record of honeys with specific characteristics by reducing the effects of fluorescence.

  7. Copper(II) complexes of prion protein PEG11-tetraoctarepeat fragment: spectroscopic and voltammetric studies.

    PubMed

    Bonomo, Raffaele P; Di Natale, Giuseppe; Rizzarelli, Enrico; Tabbì, Giovanni; Vagliasindi, Laura I

    2009-04-14

    Spectroscopic (UV-Vis and EPR) and voltammetric studies have been carried out on the copper(II) complexes with the Ac-PEG11-(PHGGGWGQ)4-NH2 (L) polypeptide. In the ratios Cu : L 3 : 1 and 4 : 1, the two [Cu3(L)H(-6)] and [Cu4(L)H(-8)] complex species have been characterized at neutral pH values. All the copper atoms occupy similar coordination sites formed by imidazole, peptidic nitrogen atoms and carbonyl oxygen atoms in a square base pyramidal geometry. Voltammetric measurements on these systems point out the cooperativity in the electron transfer processes among the copper(II) sites during their reduction. NO interaction with these polynuclear copper species is characterized by the reduction of the copper sites through the formation of two different intermediate complex species. When an excess of the Ac-PEG11-(PHGGGWGQ)4-NH2 ligand is considered, frozen solution EPR parameters and UV-Vis spectroscopic data identify the [Cu(N(im))4]2+ chromophore, which does not interact with NO.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  9. Lanthanide and transition metal complexes of bioactive coumarins: molecular modeling and spectroscopic studies.

    PubMed

    Georgieva, I; Mihaylov, Tz; Trendafilova, N

    2014-06-01

    The present paper summarizes theoretical and spectroscopic investigations on a series of active coumarins and their lanthanide and transition metal complexes with application in medicine and pharmacy. Molecular modeling as well as IR, Raman, NMR and electronic spectral simulations at different levels of theory were performed to obtain important molecular descriptors: total energy, formation energy, binding energy, stability, conformations, structural parameters, electron density distribution, molecular electrostatic potential, Fukui functions, atomic charges, and reactive indexes. The computations are performed both in gas phase and in solution with consideration of the solvent effect on the molecular structural and energetic parameters. The investigations have shown that the advanced computational methods are reliable for prediction of the metal-coumarin binding mode, electron density distribution, thermodynamic properties as well as the strength and nature of the metal-coumarin interaction (not experimentally accessible) and correctly interpret the experimental spectroscopic data. Known results from biological tests for cytotoxic, antimicrobial, anti-fungal, spasmolytic and anti-HIV activities on the studied metal complexes are reported and discussed.

  10. Studying the dwarf galaxies in nearby groups of galaxies: Spectroscopic and photometric data

    NASA Astrophysics Data System (ADS)

    Hopp, U.; Vennik, J.

    2014-11-01

    Galaxy evolution by interaction-driven transformation is probably highly efficient in groups of galaxies. Dwarf galaxies with their shallow potential are expected to reflect the interaction most prominently in their observable structure. The major aim of this series of papers is to establish a data base which allows to study the impact of group interaction onto the morphology and star-forming properties of dwarf galaxies. Firstly, we present our selection rules for target groups and the morphological selection method of target dwarf member candidates. Secondly, the spectroscopic follow-up observations with the HET are presented. Thirdly, we applied own reduction methods based on adaptive filtering to derive surface photometry of the candidates. The spectroscopic follow-up indicate a dwarf identification success rate of roughly 55 %, and a group member success rate of about 33 %. A total of 17 new low surface-brightness members is presented. For all candidates, total magnitudes, colours, and light distribution parameters are derived and discussed in the context of scaling relations. We point out short comings of the SDSS standard pipeline for surface photometry for these dim objects. We conclude that our selection strategy is rather efficient to obtain a sample of dim, low surface brightness members of groups of galaxies within the Virgo super-cluster. The photometric scaling relation in these X-ray dim, rather isolated groups does not significantly differ from those of the galaxies within the local volume.

  11. Design of and Studies with a Novel One Meter Multi - Spectroscopic Telescope

    NASA Astrophysics Data System (ADS)

    Barry, Donald James

    1996-01-01

    A traditional one-meter imaging telescope costs 250,000 and weighs several tons. A novel multi -element spectroscopic telescope is described which trades imaging ability and monolithic size for low cost and weight, producing the same light gathering power at under one-tenth the cost. A complete spectroscopic facility consisting of one-meter equivalent-aperture telescope, fiber optical feed, Newtonian-Ebert spectrograph, and automated processing software has been prototyped, constructed, and placed into operation. The total cost of materials is under 85,000. A variety of science observations have been conducted with this facility including a tomographic reconstruction of the component spectra of the massive binary Plaskett's star components, a measurement of the line-profile variability of the Be stars lambda Eridani and BK Camelopardalis, and a dynamical study of the orbit of the triple star system 55 Ursae Majoris. The instrument performs well and is now in regular use as a scheduled telescope at the Georgia State University Hard Labor Creek Observatory. Improvements continue, and the telescope continues to serve a valuable role in the GSU Astronomy program's scientific programs and pedagogical mission.

  12. A Spectroscopic Study of Impurity Behavior in Neutral-beam and Ohmically Heated TFTR Discharges

    DOE R&D Accomplishments Database

    Stratton, B. C.; Ramsey, A. T.; Boody, F. P.; Bush, C. E.; Fonck, R. J.; Groenbner, R. J.; Hulse, R. A.; Richards, R. K.; Schivell, J.

    1987-02-01

    Quantitative spectroscopic measurements of Z{sub eff}, impurity densities, and radiated power losses have been made for ohmic- and neutral-beam-heated TFTR discharges at a plasma current of 2.2 MA and toroidal field of 4.7 T. Variations in these quantities with line-average plasma density (anti n{sub e}) and beam power up to 5.6 MW are presented for discharges on a graphite movable limiter. A detailed discussion of the use of an impurity transport model to infer absolute impurity densities and radiative losses from line intensity and visible continuum measurements is given. These discharges were dominated by low-Z impurities with carbon having a considerably higher density than oxygen, except in high-anti n{sub e} ohmic discharges, where the densities of carbon and oxygen were comparable. Metallic impurity concentrations and radiative losses were small, resulting in hollow radiated power profiles and fractions of the input power radiated being 30 to 50% for ohmic heating and 30% or less with beam heating. Spectroscopic estimates of the radiated power were in good agreement with bolometrically measured values. Due to an increase in the carbon density, Z{sub eff} rose from 2.0 to 2.8 as the beam power increased from 0 to 5.6 MW, pointing to a potentially serious dilution of the neutron-producing plasma ions as the beam power increased. Both the low-Z and metallic impurity concentrations were approximately constant with minor radius, indicating no central impurity accumulation in these discharges.

  13. Improving chemical mapping algorithm and visualization in full-field hard x-ray spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Chang, Cheng; Xu, Wei; Chen-Wiegart, Yu-chen Karen; Wang, Jun; Yu, Dantong

    2013-12-01

    X-ray Absorption Near Edge Structure (XANES) imaging, an advanced absorption spectroscopy technique, at the Transmission X-ray Microscopy (TXM) Beamline X8C of NSLS enables high-resolution chemical mapping (a.k.a. chemical composition identification or chemical spectra fitting). Two-Dimensional (2D) chemical mapping has been successfully applied to study many functional materials to decide the percentages of chemical components at each pixel position of the material images. In chemical mapping, the attenuation coefficient spectrum of the material (sample) can be fitted with the weighted sum of standard spectra of individual chemical compositions, where the weights are the percentages to be calculated. In this paper, we first implemented and compared two fitting approaches: (i) a brute force enumeration method, and (ii) a constrained least square minimization algorithm proposed by us. Next, as 2D spectra fitting can be conducted pixel by pixel, so theoretically, both methods can be implemented in parallel. In order to demonstrate the feasibility of parallel computing in the chemical mapping problem and investigate how much efficiency improvement can be achieved, we used the second approach as an example and implemented a parallel version for a multi-core computer cluster. Finally we used a novel way to visualize the calculated chemical compositions, by which domain scientists could grasp the percentage difference easily without looking into the real data.

  14. An imaging and spectroscopic study of the planetary nebulae in NGC 5128 (Centaurus A). Planetary nebulae catalogues

    NASA Astrophysics Data System (ADS)

    Walsh, J. R.; Rejkuba, M.; Walton, N. A.

    2015-02-01

    Context. Planetary nebulae (PNe) are excellent tracers of the common low mass stars through their strong and narrow emission lines. The velocities of large numbers of PNe are excellent tracers of galaxy kinematics. NGC 5128, the nearest large early-type galaxy, offers the possibility to gather a large sample. Aims: Imaging and spectroscopic observations of PNe in NGC 5128 were obtained to find and measure their velocities. Combined with literature data, a large sample of high quality kinematic probes is assembled for dynamical studies. Methods: NTT imaging was obtained in 15 fields in NGC 5128 across 1° with EMMI and [O III] and off-band filters. Newly detected sources, combined with literature PN, were used as input for FLAMES multi-fibre spectroscopy in MEDUSA mode. Spectra of the 4600-5100 Å region were analysed and velocities measured based on [O III]4959, 5007 Å and often Hβ. Results: The chief results are catalogues of 1118 PN candidates and 1267 spectroscopically confirmed PNe in NGC 5128. The catalogue of PN candidates contains 1060 PNe discovered with NTT EMMI imaging and 58 from literature surveys. The spectroscopic PN catalogue has FLAMES radial velocity and emission line measurements for 1135 PNe, of which 486 are new. Another 132 PN radial velocities are available from the literature. For 629 PNe observed with FLAMES, Hβ was measured in addition to [O III]. Nine targets show double-lined or more complex profiles, and their possible origin is discussed. FLAMES spectra of 48 globular clusters were also targetted: 11 had emission lines detected (two with multiple components), but only 3 are PNe likely to belong to the host globular. Conclusions: The total of 1267 confirmed PNe in NGC 5128 with radial velocity measurements (1135 with small velocity errors) is the largest collection of individual kinematic probes in an early-type galaxy. This PN dataset, as well as the catalogue of PN candidates, are valuable resources for detailed investigation of NGC

  15. X-ray photoelectron and Raman spectroscopic studies of MeV proton irradiated graphite

    NASA Astrophysics Data System (ADS)

    Mathew, S.; Joseph, B.; Sekhar, B. R.; Dev, B. N.

    2008-07-01

    Poly-crystalline graphite samples were irradiated using 2.25 MeV H + ions with a fluence of 2 × 10 17 ions/cm 2. Magnetic ordering in highly oriented pyrolytic graphite samples have been reported earlier under the similar irradiation conditions [Esquinazi et al., Phys. Rev. Lett. 91 (2003) 227201]. In that study, the authors attribute the observed irradiation induced magnetic ordering to the formation of a mixed sp 2-sp 3 hybridized carbon atoms. In the present study, we report the X-ray photoelectron and Raman spectroscopic studies on pristine and irradiated samples. Irradiated samples are found to show an increased number of sp 3 hybridized carbon atoms. However, the Raman spectrum, specially the second order data, do indicate that the nature of the graphene lattice structure has been preserved in the irradiated samples. The mechanisms for the irradiation induced enhancement in sp 3 hybridization are discussed.

  16. Spectroscopic Studies on Eu{sup 3+} Doped Boro-Tellurite Glasses

    SciTech Connect

    Selvaraju, K.; Marimuthu, K.

    2011-07-15

    Eu{sup 3+} doped boro-tellurite glasses have been synthesized and its optical behavior have been studied and reported. The presence of varying tellurium dioxide content results changes in spectroscopic behavoir were explored through UV-VIS, and Luminescence spectra. The bonding parameters have been calculated based on the observed band positions of the absorption spectra. The Judd-Ofelt intensity parameters {Omega}{sub {lambda}} ({lambda} = 2, 4 and 6) have been determined through the luminescence spectra without applying any constraints and the results are presented. The Judd-Ofelt parameters have been used to determine various optical properties corresponding to {sup 5}D{sub 0}{yields}{sup 7}F{sub J}(J = 1,2,3 and 4) transitions of Eu{sup 3+} ions. The varying optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar studies.

  17. Spectroscopic study of N-acetylcysteine and N-acetylcystine/hydrogen peroxide complexation

    NASA Astrophysics Data System (ADS)

    Picquart, Michel; Abedinzadeh, Zohreh; Grajcar, Lydie; Baron, Marie Héléne

    1998-03-01

    A spectroscopic study of N-acetylcysteine (RSH) and N-acetylcystine (RSSR) has been performed using infrared absorption and Raman scattering in order to pinpoint the sites of complexation of these two species with H 2O 2. Molecules of RSH and RSSR were studied in KBr pellets, and in aqueous solutions of H 2O, D 2O and H 2O with H 2O 2 (1 mol l -1) to characterize the specific influence of the solvent molecules. A time-resolved Raman study was performed for RSH-H 2O 2 in aqueous solution at 1:1 molar ratio in order to observe the formation of RSSR and to discuss the mechanism of this redox reaction.

  18. Synthesis, spectroscopic characterization, DNA interaction and antibacterial study of metal complexes of tetraazamacrocyclic Schiff base

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Khanam, Sadiqa; Firdaus, Farha; Latif, Abdul; Aatif, Mohammad; Al-Resayes, Saud I.

    The template condensation reaction between benzil and 3,4-diaminotoulene resulted mononuclear 12-membered tetraimine macrocyclic complexes of the type, [MLCl2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The synthesized complexes have been characterized on the basis of the results of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz. FT-IR, 1H and 13C NMR, FAB mass, UV-vis and EPR. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for Cu(II) complex. Low conductivity data of all these complexes suggest their non-ionic nature. The interactive studies of these complexes with calf thymus DNA showed that the complexes are avid binders of calf thymus DNA. The in vitro antibacterial studies of these complexes screened against pathogenic bacteria proved them as growth inhibiting agents.

  19. Development of in-situ full-field spectroscopic imaging analysis and application on Li-ion battery using transmission x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Chen-Wiegart, Yu-chen K.; Wang, Jiajun; Wang, Jun

    2013-09-01

    This paper presents the advance in spectroscopic imaging technique and analysis method from the newly developed transmission x-ray microscopy (TXM) at the beamline X8C of National Synchrotron Light Source. Through leastsquares linear combination fitting we developed on the in situ spectroscopic images, a time-dependent and spatially resolved chemical composition mapping can be obtained and quantitatively analyzed undergone chemical/electrochemical reactions. A correlation of morphological evolution, chemical state distribution changes and reaction conditions can be revealed. We successfully applied this method to study the electrochemical evolution of CuO, an anode material of Li-ion battery, during the lithiation-delitiation cycling.

  20. The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Search for [CII] Line and Dust Emission in 6

    NASA Astrophysics Data System (ADS)

    Aravena, M.; Decarli, R.; Walter, F.; Bouwens, R.; Oesch, P. A.; Carilli, C. L.; Bauer, F. E.; Da Cunha, E.; Daddi, E.; Gónzalez-López, J.; Ivison, R. J.; Riechers, D. A.; Smail, I.; Swinbank, A. M.; Weiss, A.; Anguita, T.; Bacon, R.; Bell, E.; Bertoldi, F.; Cortes, P.; Cox, P.; Hodge, J.; Ibar, E.; Inami, H.; Infante, L.; Karim, A.; Magnelli, B.; Ota, K.; Popping, G.; van der Werf, P.; Wagg, J.; Fudamoto, Y.

    2016-12-01

    We present a search for [C ii] line and dust continuum emission from optical dropout galaxies at z > 6 using ASPECS, our Atacama Large Millimeter submillimeter Array Spectroscopic Survey in the Hubble Ultra-deep Field (UDF). Our observations, which cover the frequency range of 212-272 GHz, encompass approximately the range of 6 < z < 8 for [C ii] line emission and reach a limiting luminosity of L [C ii] ˜ (1.6-2.5) × 108 L ⊙. We identify 14 [C ii] line emitting candidates in this redshift range with significances >4.5σ, two of which correspond to blind detections with no optical counterparts. At this significance level, our statistical analysis shows that about 60% of our candidates are expected to be spurious. For one of our blindly selected [C ii] line candidates, we tentatively detect the CO(6-5) line in our parallel 3 mm line scan. None of the line candidates are individually detected in the 1.2 mm continuum. A stack of all [C ii] candidates results in a tentative detection with S 1.2 mm = 14 ± 5 μJy. This implies a dust-obscured star-formation rate (SFR) of (3 ± 1) M ⊙ yr-1. We find that the two highest-SFR objects have candidate [C ii] lines with luminosities that are consistent with the low-redshift L [C ii] versus SFR relation. The other candidates have significantly higher [C ii] luminosities than expected from their UV-based SFR. At the current sensitivity, it is unclear whether the majority of these sources are intrinsically bright [C ii] emitters, or spurious sources. If only one of our line candidates was real (a scenario greatly favored by our statistical analysis), we find a source density for [C ii] emitters at 6 < z < 8 that is significantly higher than predicted by current models and some extrapolations from galaxies in the local universe.

  1. Batch sorption and spectroscopic speciation studies of neptunium uptake by montmorillonite and corundum

    NASA Astrophysics Data System (ADS)

    Elo, O.; Müller, K.; Ikeda-Ohno, A.; Bok, F.; Scheinost, A. C.; Hölttä, P.; Huittinen, N.

    2017-02-01

    Detailed information on neptunium(V) speciation on montmorillonite and corundum surfaces was obtained by batch sorption and desorption studies combined with surface complexation modelling using the Diffuse Double-Layer (DDL) model, in situ time-resolved Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) and X-ray absorption (XAS) spectroscopies. The pH-dependent batch sorption studies and the spectroscopic investigations were conducted under carbonate-free conditions in 10 mM NaClO4 or 10 mM NaCl. Solid concentrations of 0.5 g/l and 5 g/l were used depending on the experiment. The neptunium(V) desorption from the two mineral surfaces was investigated at pH values ranging from 8 to 10, using the replenishment technique. Neptunium(V) was found to desorb from the mineral surface, however, the extent of desorption was dependent on the solution pH. The desorption of neptunium(V) was confirmed in the ATR FT-IR spectroscopic studies at pH 10, where all of the identified inner-sphere complexed neptunium(V), characterized by a vibrational band at 790 cm-1, was desorbed from both mineral surfaces upon flushing the mineral films with a blank electrolyte solution. In XAS investigations of neptunium(V) uptake by corundum, the obtained structural parameters confirm the formation of an inner-sphere complex adsorbed on the surface in a bidentate fashion. As the inner-sphere complexes found in the IR-studies are characterized by identical sorption bands on both corundum and montmorillonite, we tentatively assigned the neptunium(V) inner-sphere complex on montmorillonite to the same bidentate complex found on corundum in the XAS investigations. Finally, the obtained batch sorption and spectroscopic results were modelled with surface complexation modelling to explain the neptunium(V) speciation on montmorillonite over the entire investigated pH range. The modelling results show that cation exchange in the interlayer space as well as two pH-dependent surface complexes

  2. Preferential binding of fisetin to the native state of bovine serum albumin: spectroscopic and docking studies.

    PubMed

    Singha Roy, Atanu; Pandey, Nitin Kumar; Dasgupta, Swagata

    2013-04-01

    We have investigated the binding of the biologically important flavonoid fisetin with the carrier protein bovine serum albumin using multi-spectroscopic and molecular docking methods. The binding constants were found to be in the order of 10(4) M(-1) and the number of binding sites was determined as one. MALDI-TOF analyses showed that one fisetin molecule binds to a single bovine serum albumin (BSA) molecule which is also supported by fluorescence quenching studies. The negative Gibbs free energy change (∆G°) values point to a spontaneous binding process which occurs through the presence of electrostatic forces with hydrophobic association that results in a positive entropy change (+51.69 ± 1.18 J mol(-1) K(-1)). The unfolding and refolding of BSA in urea have been studied in absence and presence of fisetin using steady-state fluorescence and lifetime measurements. Urea denaturation studies indicate that fisetin is gradually released from its binding site on the protein. In the absence of urea, an increase in temperature that causes denaturation of the protein results in the release of fisetin from its bound state indicating that fisetin binds only to the native state of the protein. The circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic studies showed an increase in % α-helix content of BSA after binding with fisetin. Site marker displacement studies in accordance with the molecular docking results suggested that fisetin binds in close proximity of the hydrophobic cavity in site 1 (subdomain IIA) of the protein. The PEARLS (Program of Energetic Analysis of Receptor Ligand System) has been used to estimate the interaction energy of fisetin with BSA and the results are in good correlation with the experimental findings.

  3. A Morpho-kinematic and Spectroscopic study of Bipolar Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Clyne, Niall

    2015-09-01

    In this thesis, studies of the kinematic properties for a sample of Galactic bipolar planetary nebulae, based on optical and infrared observations, were performed using a morpho-kinematic code, optical and NIR diagnostic diagrams, and techniques using data analyses. The mechanisms that form complex bipolar planetary nebulae remain unclear, and their shapes can be generated either as a planetary or symbiotic nebula. The origin of the material ionised by the white dwarf is very different in these two scenarios, and it complicates the understanding of the morphologies of planetary nebulae. The physical properties, structure, and dynamics of the bipolar nebulae, MyCn 18, M 2-9, Mz 3, Hen 2-104, and Abell 14, are each investigated in detail with the aim of understanding their nature, shaping mechanisms, and evolutionary history. For MyCn 18, VLT infrared images, VLT ISAAC infrared spectra, and long-slit optical echelle spectra are used to investigate the inner and outer regions of the nebula. The morpho-kinematic modelling tool shape was used to firmly constrain the structure and kinematics of the source. A timescale analysis was used to help determine the kinematical age of the nebula and its main components. A spectroscopic study of MyCn 18's central region reveals the detailed make-up of its nebular composition. Molecular hydrogen, atomic helium, and Brackett gamma emission are detected in the central regions. ISAAC spectra from a slit position along the narrow waist of the nebula demonstrate that the ionised gas resides closer to the centre of the nebula than the molecular emission. A final reconstructed 3-D model of MyCn 18 was generated, providing kinematical information on the expansion velocity of its nebular components by means of position-velocity arrays (or observed long-slit spectra). A kinematical age of the nebula and its components were obtained using the position-velocity arrays and timescale analysis. For M 2-9, Mz 3, and Hen 2-104, long-slit optical

  4. Interaction between serum albumins and sonochemically synthesized cadmium sulphide nanoparticles: a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Naveenraj, Selvaraj; Asiri, Abdullah M.; Anandan, Sambandam

    2013-05-01

    Cadmium Sulphide nanoparticles approximately 5-10 nm in size range were synthesized by sonochemical technique, which follows acoustic cavitation phenomenon and generates nanoparticles with a smaller size range and higher surface area. The in vitro binding interaction of these sonochemically synthesized CdS nanoparticles with serum albumins (SA) were investigated using UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopic techniques since CdS nanoparticles has biological applications such as cellular labelling and deep-tissue imaging. UV-Vis absorption and fluorescence studies confirm that CdS nanoparticles bind with SA through ground state complex formation (static quenching mechanism). The results suggest that sonochemically synthesized CdS nanoparticles interact with HSA more than that of BSA and these nanoparticles can be easily transported and rapidly released to the targets by serum albumins. CD studies confirmed the conformational change of serum albumins on the interaction of CdS nanoparticles.

  5. Synthesis, Spectroscopic, ac Conductivity and Thermal Studies on Co(III) Acetylacetonate-Iodine Complex

    NASA Astrophysics Data System (ADS)

    Hashem, H. A.; Refat, M. S.

    A spectrophotometric study of 1:1 donor-acceptor complex, cobalt (III) acetylacetonate (donor) and iodine (σ-acceptor) has been preformed. The equilibrium constants, (K) and the absorpitivity (ɛ) for the formation of the iodine complex have been calculated. The predicted structure of the solid triiodide charge-transfer complex reported in this study is further supported by thermal, far and mid infrared spectroscopic measurements. Electron transfer from Co (acac = 2, 4-pentanedionate)3 to iodine leads to the formation of an organic semiconductor with the formula of [Co(acac)3]_2 I+. I3-. The kinetic parameters (nonisothermal method) for their decomposition have been evaluated by graphical methods using the equations of Freeman-Carroll (FC), Horowitz-Metzger (HM) and Coats-Redfern (CR). The ac conductivity and dielectric properties of [Co(acac)3]_2 I+. I3- have been measured over the frequency 50-106 Hz at temperature 298 K.

  6. Electronic properties of diphenyl-s-tetrazine and some related oligomers. An spectroscopic and theoretical study

    NASA Astrophysics Data System (ADS)

    Moral, Mónica; García, Gregorio; Peñas, Antonio; Garzón, Andrés; Granadino-Roldán, José M.; Melguizo, Manuel; Fernández-Gómez, Manuel

    2012-10-01

    This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph2Tz) and some oligomeric derivatives. Ph2Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV-Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

  7. Defect study in ZnO related structures—A multi-spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Ling, C. C.; Cheung, C. K.; Gu, Q. L.; Dai, X. M.; Xu, S. J.; Zhu, C. Y.; Luo, J. M.; Zhu, C. Y.; Tam, K. H.; Djurišić, A. B.; Beling, C. D.; Fung, S.; Lu, L. W.; Brauer, G.; Anwand, W.; Skorupa, W.; Ong, H. C.

    2008-10-01

    ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H 2O 2 pre-treatment induced ohmic to rectifying contact conversion on Au/ n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure.

  8. Electrochemical and spectroscopic studies of the oxidation mechanism of the herbicide propanil.

    PubMed

    Garrido, E M; Lima, J L F C; Delerue-Matos, C; Borges, F; Silva, A M S; Piedade, J A P; Oliveira Brett, A M

    2003-02-12

    Electrochemical oxidation of propanil in deuterated solutions was studied by cyclic, differential pulse, and square wave voltammetry using a glassy carbon microelectrode. The oxidation of propanil in deuterated acid solutions occurs at the nitrogen atom of the amide at a potential of +1.15 V vs Ag/AgCl. It was also found that, under the experimental conditions used, protonation at the oxygen atom of propanil occurs, leading to the appearance of another species in solution which oxidizes at +0.60 V. The anodic peak found at +0.79 V vs Ag/AgCl in deuterated basic solutions is related to the presence of an anionic species in which a negative charge is on the nitrogen atom. The electrochemical data were confirmed by the identification of all the species formed in acidic and basic deuterated solutions by means of NMR spectroscopy. The results are supported by electrochemical and spectroscopic studies of acetanilide in deuterated solutions.

  9. Accurate molecular structure and spectroscopic properties for nucleobases: A combined computational - microwave investigation of 2-thiouracil as a case study

    PubMed Central

    Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo; Peña, Isabel; Cabezas, Carlos; Alonso, José L.

    2015-01-01

    The computational composite scheme purposely set up for accurately describing the electronic structure and spectroscopic properties of small biomolecules has been applied to the first study of the rotational spectrum of 2-thiouracil. The experimental investigation was made possible thanks to the combination of the laser ablation technique with Fourier Transform Microwave spectrometers. The joint experimental – computational study allowed us to determine accurate molecular structure and spectroscopic properties for the title molecule, but more important, it demonstrates a reliable approach for the accurate investigation of isolated small biomolecules. PMID:24002739

  10. SPECTROSCOPIC STUDIES OF THE ANAEROBIC ENZYME-SUBSTRATE COMPLEX OF CATECHOL 1,2-DIOXYGENASE

    PubMed Central

    Horsman, Geoff P.; Jirasek, Andrew; Vaillancourt, Frédéric H.; Barbosa, Christopher J.; Jarzecki, Andrzej A.; Xu, Changliang; Mekmouche, Yasmina; Spiro, Thomas G.; Lipscomb, John D.; Blades, Michael W.; Turner, Robin F.B.; Eltis, Lindsay D.

    2008-01-01

    The basis of the respective regiospecificities of intradiol and extradiol dioxygenase is poorly understood and may be linked to the protonation state of the bidentate-bound catechol in the enzyme:substrate complex. Previous ultraviolet resonance Raman (UVRR) and UV-visible (UV-vis) difference spectroscopic studies demonstrated that in extradiol dioxygenases, the catechol is bound to the Fe(II) as a monoanion. In this study, we use the same approaches to demonstrate that in catechol 1,2-dioxygenase (C12O), an intradiol enzyme, the catechol binds to the Fe(III) as a dianion. Specifically, features at 290 nm and 1550 cm−1 in the UV-vis and UVRR difference spectra, respectively, are assigned to dianionic catechol based on spectra of the model compound, ferric tris(catecholate). The UVRR spectroscopic band assignments are corroborated by density functional theory (DFT) calculations. In addition, negative features at 240 nm in UV-vis difference spectra and at 1600, 1210, and 1175 cm−1 in UVRR difference spectra match those of a tyrosinate model compound, consistent with protonation of the axial tyrosinate ligand when it is displaced from the ferric ion coordination sphere upon substrate binding. The DFT calculations ascribe the asymmetry of the bound dianionic substrate to the trans donor effect of an equatorially ligated tyrosinate ligand. In addition, the computations suggest that trans donation from the tyrosinate ligand may facilitate charge-transfer from the substrate to yield the iron-bound semiquinone transition state, which is capable of reacting with dioxygen. In illustrating the importance of ligand trans effects in a biological system, the current study demonstrates the power of combining difference UVRR and optical spectroscopies to probe metal ligation in solution. PMID:16316234

  11. Spectroscopic and nonlinear optical studies of pure and Nd-doped lanthanum strontium borate glasses

    NASA Astrophysics Data System (ADS)

    Harde, G. B.; Muley, G. G.

    2016-05-01

    Borate glasses of the system xNd2O3-(1-x) La2O3-SrCO3-10H3BO3 (with x = 0 and 0.05) were prepared by using a convectional melt quenching technique. The amorphous nature of the quenched glasses has been confirmed by powder X-ray diffraction analysis. In order to study the spectroscopic and nonlinear optical properties of fabricated glasses, ultraviolet-visible transmission spectroscopy and open aperture z-scan measurements have been employed. In Nd doped glasses, the transition 4I9/2 → 4G5/2 + 2G7/2 has found more prominent than the other transitions. Optical band gap energies of glasses have been determined and found less for Nd doped glass.

  12. Thermal dependence of optical properties of silver thin films studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Sundari, S. Tripura; Dash, S.; Tyagi, A. K.

    2012-06-01

    The thermal dependence of the dielectric constants of silver thin films were investigated between 300 K and 650 K by spectroscopic ellipsometer in the energy range 1.5 to 5 eV. The studies showed an increase in the imaginary part (ɛ2) of the dielectric function, a shift of ˜300 meV in the onset of the main absorption (L3-L2'(EF)), appearance of additional absorption above 500 K which is attributed to (L2'- L1) and increased broadening of the absorption spectra owing to smearing of Fermi level. It was found that the unscreened plasma frequency ωpu associated with resonant oscillations of conduction electrons increased while the relaxation time decreased with increase in temperature.

  13. Raman spectroscopic study of high-pressure behavior of Ag3[Co(CN)6

    NASA Astrophysics Data System (ADS)

    Rao, Rekha; Achary, S. N.; Tyagi, A. K.; Sakuntala, T.

    2011-08-01

    In situ Raman spectroscopic studies have been carried out on Ag3[Co(CN)6] at high pressures up to 16 GPa. From the pressure dependence of the Raman frequencies, the mode Grüneisen parameters in the trigonal and the monoclinic phases are obtained. Besides the reported trigonal-to-monoclinic transition at 0.2 GPa, it is observed that the compound shows pressure-induced amorphization above 13 GPa. The recovered sample shows features characteristic of amorphous carbon nitride, indicating the decomposition of the parent compound in the pressure-reducing cycle. Temperature dependence of the mode frequencies over the range 80-290 K is also investigated, from which the modes that are more anharmonic than other modes are identified.

  14. Spectroscopic and theoretical study of the o-vanillin hydrazone of the mycobactericidal drug isoniazid

    NASA Astrophysics Data System (ADS)

    González-Baró, Ana C.; Pis-Diez, Reinaldo; Parajón-Costa, Beatriz S.; Rey, Nicolás A.

    2012-01-01

    A complete and detailed study of the hydrazone obtained from condensation of antituberculous isoniazid (hydrazide of the isonicotinic acid, INH) and o-vanillin (2-hydroxy-3-methoxybenzaldehyde, o-HVa) is performed. It includes structural and spectroscopic analyses, comparing experimental and theoretical results. The compound was obtained as a chloride of the pyridinic salt (INHOVA +Cl -) but it will be referred as INHOVA for the sake of simplicity. The conformational space was searched and optimized geometries were determined both in gas phase and including solvent effects. Vibrational (IR and Raman), electronic and NMR spectra were registered and assigned with the help of computational methods based on the Density Functional Theory. Isoniazid hydrazones are good candidates for therapeutic agents against tuberculosis with conserved efficiency and lower toxicity and resistance than parent INH.

  15. Growth of vacuum evaporated ultraporous silicon studied with spectroscopic ellipsometry and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Kaminska, Kate; Amassian, Aram; Martinu, Ludvik; Robbie, Kevin

    2005-01-01

    Using a combination of variable-angle spectroscopic ellipsometry and scanning electron microscopy, we investigated the scaling behavior of uniaxially anisotropic, ultraporous silicon manufactured with glancing angle deposition. We found that both the diameter of the nanocolumns and the spacing between them increase with film thickness according to a power-law relationship consistent with self-affine fractal growth. An ellipsometric model is proposed to fit the optical properties of the anisotropic silicon films employing an effective medium approximation mixture of Tauc-Lorentz oscillator and void. This study shows that the optical response of silicon films made at glancing incidence differs significantly from that of amorphous silicon prepared by other methods due to highly oriented nanocolumn formation and power-law scaling.

  16. Wrapping Together Galactic Archaeology and Interstellar Medium Studies in Large Spectroscopic Surveys

    NASA Astrophysics Data System (ADS)

    Kos, J.

    2016-10-01

    The cold interstellar medium (ISM) in our galaxy is usually observed at wavelengths other than optical. But optical spectroscopic surveys of stars give unprecedented information that is valuable also for ISM studies because they cover millions of lines-of-sight penetrating regions in and out of the Galactic plane that most all-sky surveys. Big advantages are distances to observed stars from which we infer distances to clumps of the ISM. The ISM is detected as scarce absorptions of several atoms and simple molecules and also as diffuse interstellar bands (DIBs), weak but numerous absorption features at visible and near IR wavelengths. With the enormous amount of information the surveys provide we can start doing galactic archaeology from the ISM point of view. Even though the principles are very different for star and gas dynamics, the starting points are the same. Here we present some results that are the first steps toward the galactic archaeology of the ISM.

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

    PubMed

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

    2017-05-15

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

  18. Biophysical influence of coumarin 35 on bovine serum albumin: Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Bayraktutan, Tuğba; Onganer, Yavuz

    2017-01-01

    The binding mechanism and protein-fluorescence probe interactions between bovine serum albumin (BSA) and coumarin 35 (C35) was investigated by using UV-Vis absorption and fluorescence spectroscopies since they remain major research topics in biophysics. The spectroscopic data indicated that a fluorescence quenching process for BSA-C35 system was occurred. The fluorescence quenching processes were analyzed using Stern-Volmer method. In this regard, Stern-Volmer quenching constants (KSV) and binding constants were calculated at different temperatures. The distance r between BSA (donor) and C35 (acceptor) was determined by exploiting fluorescence resonance energy transfer (FRET) method. Synchronous fluorescence spectra were also studied to observe information about conformational changes. Moreover, thermodynamics parameters were calculated for better understanding of interactions and conformational changes of the system.

  19. A dielectric spectroscopic study of the disperse structure of asphaltene solutions at high pressures

    SciTech Connect

    Syunyaev, R.Z.; Sh. Abid, R.

    1994-03-01

    The disperse structure of oil asphaltenes in benzene and toluene solutions at different temperatures and concentrations were studied at pressures up to 1.0 GPa. The polarity of the asphaltene molecules allows the dielectric spectroscopic method to be used. A sharp increase in the relaxation time and the sizes of the asphaltene aggregates, calculated according to the Debye model near the phase transition point, were found in the benzene solution. The pressure value corresponding to crystallization is much higher in the toluene solution, and only the border region can be investigated. An explanation of the pressure dependences of the relaxation times are presented. The activation energies and the coefficients of isothermal compressibility are calculated.

  20. FTIR spectroscopic studies of lipid dynamics in phytosphingosine ceramide models of the stratum corneum lipid matrix.

    PubMed

    Rerek, Mark E; Van Wyck, Dina; Mendelsohn, Richard; Moore, David J

    2005-03-01

    IR spectroscopic studies are reported for N-stearyl-D-erythro-phytosphingosine (Cer NP) and N-stearyl-2-hydroxy-D-erythro-phytosphingosine (Cer AP) in a hydrated model of the skin lipid barrier comprised of equimolar mixtures of each ceramide with cholesterol and d(35)-stearic acid. Examination of the methylene stretching, rocking and bending modes reveal some rotational freedom and hexagonal packing in both the ceramide and stearic acid chains. Analysis of the acid carbonyl stretch and the ceramide Amide I modes show both shift to higher frequencies, indicating weaker hydrogen bonding, in the mixed systems compared to the pure materials. For both systems, the fatty acid chain disordering temperatures are significantly increased from those of the pure acids. The observed behaviors of these phytosphingosine ceramide systems are fundamentally different from the previously reported analogous sphingosine ceramide systems. The implications of these observations for lipid organization in the stratum corneum are briefly discussed.

  1. Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

    NASA Astrophysics Data System (ADS)

    Chang, J.-K.; Hsu, C.-C.; Liu, S.-Y.; Wu, C.-I.; Gharib, M.; Yeh, N.-C.

    2016-06-01

    The environmental aging effect of doped graphene is investigated as a function of the organic doping species, humidity, and the number of graphene layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared spectroscopy, and electrical transport measurements. It is found that higher humidity and structural defects induce faster degradation in doped graphene. Detailed analysis of the spectroscopic data suggest that the physical origin of the aging effect is associated with the continuing reaction of H2O molecules with the hygroscopic organic dopants, which leads to formation of excess chemical bonds, reduction in the doped graphene carrier density, and proliferation of damages from the graphene grain boundaries. These environmental aging effects are further shown to be significantly mitigated by added graphene layers.

  2. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    PubMed Central

    Kurhekar, Anil Sudhakar; Apte, Prakash R

    2014-01-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces. PMID:24619506

  3. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    NASA Astrophysics Data System (ADS)

    Kurhekar, Anil Sudhakar; Apte, Prakash R.

    2013-02-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces.

  4. Laser Raman and ac impedance spectroscopic studies of PVA: NH 4NO 3 polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Hema, M.; Selvasekarapandian, S.; Hirankumar, G.; Sakunthala, A.; Arunkumar, D.; Nithya, H.

    2010-01-01

    Ion conducting polymer electrolyte PVA:NH 4NO 3 has been prepared by solution casting technique and characterized using XRD, Raman and ac impedance spectroscopic analyses. The amorphous nature of the polymer films has been confirmed by XRD and Raman spectroscopy. An insight into the deconvoluted Raman peaks of υ1 vibration of NO 3- anion for the polymer electrolyte reveals the dominancy of ion aggregates at higher NH 4NO 3 concentration. From the ac impedance studies, the highest ion conductivity at 303 K has been found to be 7.5 × 10 -3 S cm -1 for 80PVA:20NH 4NO 3. The conductivity of the polymer electrolytes has been found to depend on the degree of dissociation of the salt in the host polymer matrix. The combination of the above-mentioned analyses has proven worth while and in fact necessary in order to achieve better understanding of these complex systems.

  5. Study of biological reaction in cancer cell with spectroscopic imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Da; Hsu, Hao Yun; Khaleel, Mai Ibrahim; Chang, Yia-Chung; Wu, Chien-Hsun; Wu, Han-Chung

    2016-09-01

    We present experimental studies of live cancer cells via microscopic imaging ellipsometry (MIE). The Rotating Compensator Ellipsometry (RCE) is used for our measurements. Ellipsometry spectra with signals integrated over a 20μm×20μm area in visible range (450nm to 750nm) are obtained with the Optrel MULTISKOP system for both specular reflection and off-specular scattering. The microscopic ellipsometry (ME) images at a few fixed wavelengths within the same range were also analyzed. Dielectric constants for glass slide, culture fluid, and glass cover plate were firstly characterized by spectroscopic ellipsometry measurements, which can be used in the simulation for MIE measurements of cancer cells embedded in the culture fluid and sandwiched between a glass slide and cover plate. The measured ME spectra and images of cancer cells before and after medicine injection are measured and analyzed.

  6. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga)

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  7. Photometric and spectroscopic study of the new FUor star V2493 Cyg

    NASA Astrophysics Data System (ADS)

    Semkov, Evgeni H.; Peneva, Stoyanka P.; Ibryamov, Sunay I.

    2017-01-01

    The recent results from photometric and spectroscopic study of the FUor star V2493 Cyg (HBC 722) are presented in the paper. The outburst of V2493 Cyg was registered during the summer of 2010 before the brightness of the star reached the maximum value. V2493 Cyg is the first FUor object, whose outburst was observed from its very beginning in all spectral ranges. The recent photometric data show that the star keeps its maximum brightness during the period September 2013 - Ocober 2016 and the recorded amplitude of the outburst is ΔV=5.1 mag. Consequently, the outburst of V2493 Cyg lasts for more than six years. Our spectral observations showed strong variability in the profiles and the intensity of emission lines especially for Hα line. We expect that the interest in this object will increase in the coming years and the results will help to explore the nature of young stars.

  8. Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study

    SciTech Connect

    Sowińska, Małgorzata Henkel, Karsten; Schmeißer, Dieter; Kärkkänen, Irina; Schneidewind, Jessica; Naumann, Franziska; Gruska, Bernd; Gargouri, Hassan

    2016-01-15

    The process parameters' impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiO{sub x}N{sub y}) films was studied. Titanium(IV)isopropoxide in combination with NH{sub 3} plasma and tetrakis(dimethylamino)titanium by applying N{sub 2} plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current–voltage: I-V and capacitance–voltage: C-V) methods. The O/N ratio in the TiO{sub x}N{sub y} films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film properties can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination.

  9. Raman spectroscopic study of “The Malatesta”: A Renaissance painting?

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G. M.; Vandenabeele, Peter; Benoy, Timothy J.

    2015-02-01

    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.

  10. Molecular interactions of flavonoids to pepsin: Insights from spectroscopic and molecular docking studies.

    PubMed

    Zeng, Hua-Jin; Yang, Ran; Liang, Huili; Qu, Ling-Bo

    2015-01-01

    In the work described on this paper, the inhibitory effect of 10 flavonoids on pepsin and the interactions between them were investigated by a combination of spectroscopic and molecular docking methods. The results indicated that all flavonoids could bind with pepsin to form flavonoid-pepsin complexes. The binding parameters obtained from the data at different temperatures revealed that flavonoids could spontaneously interact with pepsin mainly through electrostatic forces and hydrophobic interactions with one binding site. According to synchronous and three-dimensional fluorescence spectra and molecular docking results, all flavonoids bound directly into the enzyme cavity site and the binding influenced the microenvironment and conformation of the pepsin activity site which resulted in the reduced enzyme activity. The present study provides direct evidence at a molecular level to understand the mechanism of digestion caused by flavonoids.

  11. Vibrational Spectroscopic Studies on Some Double Alkali Tungstates Belonging to Orthorhombic Class at Room Temperature

    SciTech Connect

    Sharaff, Usha; Bajpai, P. K.; Choudhary, R. N. P.

    2011-11-22

    Room temperature IR and Raman spectra of rubidium lithium tungstate and sodium lithium tungstates belonging to double alkali tungstate family are investigated using group theoretical methods. Observed internal and lattice modes in both systems studied are assigned. Analysis of spectral behavior reveals that the effect of site potential around tungstates ion is weak and the factor group splitting is operative. Differences in the lattice mode mixing and splitting of internal modes is influenced by the statistical ordering between two alkali ions having large and small ionic radii and is explained using size and charge effect observed earlier in scheelite type of structure. Thus, vibrational spectroscopic analysis may be a tool to understand the alkali ion ordering in double alkali systems.

  12. Fe-complex of a tetraamido macrocyclic ligand: Spectroscopic characterization and catalytic oxidation studies

    NASA Astrophysics Data System (ADS)

    Sullivan, Shane Z.; Ghosh, Anindya; Biris, Alexandru S.; Pulla, Sharon; Brezden, Anna M.; Collom, Samulel L.; Woods, Ross M.; Munshi, Pradip; Schnackenberg, Laura; Pierce, Brad S.; Kannarpady, Ganesh K.

    2010-10-01

    This work presents the spectroscopic characterization and reaction studies of a Fe III-complex (2) of a tetraamido macrocyclic ligand (1, 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[a,g]cyclotridecene-6,7,14,16-tetraone). 2 was characterized primarily by means of EPR. In agreement with the magnetic moment ( μeff = 3.87 BM), EPR spectroscopy of 2 shows signals consistent with S = 3/2 intermediate-spin ferric-iron. Besides EPR, mass spectrometry, UV/vis spectroscopy and cyclic voltammetry were used to further characterize 2. 2 is soluble in water and activates hydrogen peroxide under ambient conditions. 2 catalytically bleaches dyes, pulp and paper effluents and oxidizes several amines to their corresponding N-oxides with high turnover number and good yields.

  13. Molecular spectroscopic study on the interaction of tetracyclines with serum albumins

    NASA Astrophysics Data System (ADS)

    Bi, Shuyun; Song, Daqian; Tian, Yuan; Zhou, Xin; Liu, Zhongying; Zhang, Hanqi

    2005-02-01

    A molecular spectroscopic investigation of the interaction between tetracyclines antibiotics and human serum albumin or bovine serum albumin was reported. The influences of some metal ions on the interaction were also studied. When tetracyclines drugs were added into the solution containing serum albumins, the fluorescence intensity of serum albumins decreased with the increasing of the drugs concentrations, which is due to the formation of new non-fluorescence complexes of drug-serum albumin. The tetracyclines acted as quenchers and quenched the fluorescence of the serum albumins. The binding constants and the number of the binding sites of the reaction of tetracyclines and serum albumins were obtained. The main sorts of acting force between the drugs and serum albumins were found and the action distances and the energy transfer efficiencies between donor-acceptor were calculated based on the Föster energy transference.

  14. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga).

    PubMed

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  15. Spectroscopic and dynamical studies of highly energized small polyatomic molecules. Technical progress report, July 1, 1993--October 31, 1994

    SciTech Connect

    Field, R.W.; Silbey, R.J.

    1995-02-01

    This is a progress report on a project to spectroscopically study small polyatomic molecules which are highly excited. The authors describe work on acetylene (HCCH) and HCO. Their work involves dispersed fluorescence spectroscopy, and the development and application of superpolyad models for studying intramolecular vibrational redistribution.

  16. ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: CO Luminosity Functions and the Evolution of the Cosmic Density of Molecular Gas

    NASA Astrophysics Data System (ADS)

    Decarli, Roberto; Walter, Fabian; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Ivison, R. J.; Popping, Gergö; Riechers, Dominik; Smail, Ian R.; Swinbank, Mark; Weiss, Axel; Anguita, Timo; Assef, Roberto J.; Bauer, Franz E.; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Dickinson, Mark; Elbaz, David; Gónzalez-López, Jorge; Ibar, Edo; Infante, Leopoldo; Hodge, Jacqueline; Karim, Alex; Le Fevre, Olivier; Magnelli, Benjamin; Neri, Roberto; Oesch, Pascal; Ota, Kazuaki; Rix, Hans-Walter; Sargent, Mark; Sheth, Kartik; van der Wel, Arjen; van der Werf, Paul; Wagg, Jeff

    2016-12-01

    In this paper we use ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field in band 3 and band 6, to place blind constraints on the CO luminosity function and the evolution of the cosmic molecular gas density as a function of redshift up to z ˜ 4.5. This study is based on galaxies that have been selected solely through their CO emission and not through any other property. In all of the redshift bins the ASPECS measurements reach the predicted “knee” of the CO luminosity function (around 5 × 109 K km s-1 pc2). We find clear evidence of an evolution in the CO luminosity function with respect to z ˜ 0, with more CO-luminous galaxies present at z ˜ 2. The observed galaxies at z ˜ 2 also appear more gas-rich than predicted by recent semi-analytical models. The comoving cosmic molecular gas density within galaxies as a function of redshift shows a drop by a factor of 3-10 from z ˜ 2 to z ˜ 0 (with significant error bars), and possibly a decline at z > 3. This trend is similar to the observed evolution of the cosmic star formation rate density. The latter therefore appears to be at least partly driven by the increased availability of molecular gas reservoirs at the peak of cosmic star formation (z ˜ 2).

  17. Spectroscopic Studies on the Photochemical transformation of Tannic Acid as a Model for HULIS in Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Cowen, S.; Al-Abadleh, H. A.

    2009-05-01

    Little is known about the photochemical transformation of humic like substances (HULIS) in atmospheric aerosols, and the role of adsorbed water and photosensitizers in this photochemistry. We present in-situ and surface-sensitive spectroscopic studies on the photochemical transformation of tannic acid in the absence and presence of sodium nitrite salt. Tannic acid was chosen as a synthetic proxy for HULIS because it has a defined molecular structure with elemental composition similar to that determined for atmospheric HULIS. Photochemical studies were conducted using diffuse reflectance infrared spectroscopy (DRIFTS) as a function of time (3 hrs), relative humidity (5-50%) and total irradiance (7-100 Wm-2). DRIFTS has proven to be a powerful tool for studying the heterogeneous chemistry of model components in aerosols. Preliminary spectral results show loss and growth features suggesting bonds breakage and formation of carboxylate or organic nitrogen species. The growth of the band assigned to the bending mode of water with irradiation time was also observed and suggests an increase in the hydrophilicity of tannic acid. The structure of water adsorbed on tannic acid resembles that of water at the interface with organic solvents. The implication of these results to the field of aerosols aging due to photochemistry will be discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

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

  19. Molecular hydraulic properties of montmorillonite: a polarized fourier transform infrared spectroscopic study.

    PubMed

    Amarasinghe, Priyanthi M; Katti, Kalpana S; Katti, Dinesh R

    2008-12-01

    Understanding the rates at which fluid flows into clay interlayers at the molecular level is fundamental to designing an effective clay barrier system. In this work, molecular interactions at the Na-montmorillonite (MMT)-water interface, emphasizing the flow properties of the clay interlayer, have been studied at the molecular and nanoscale level using polarized Fourier transform infrared (FT-IR) spectroscopic and X-ray diffraction (XRD) techniques. Clay-water slurries were smeared on inert gold-coated metal substrates for FT-IR experiments and slurries were smeared on quartz plates for XRD experiments. By analyzing the O-H stretching and H-O-H bending vibrations in clay slurries, it was concluded that the molecular behavior of interlayer water is significantly different from the molecular behavior of bulk water. With increasing clay-water interaction time, it was also seen that the Si-O stretching bands of clay are being significantly altered by the water molecules in the interlayer. Using these spectroscopic techniques we have estimated the time required for water to flow into the clay interlayer. Further, by analyzing the particle size of the clay using atomic force microscopy (AFM) imaging, we were able to estimate the flow velocity of the water in the clay interlayer. This velocity is found to be 3.23 x 10(-9) cm/s. This flow velocity was found to be of the same order of magnitude as the hydraulic conductivity of smectite-type clay reported elsewhere. Also described in this work is the correct positioning of the Si-O out-of-plane vibration band of MMT at the two-layer saturation level in the interlayer. This band was only observed in p-polarized spectra at 1211 cm(-1). Thus, we attribute this band to the Si-O out-of-plane vibration band.

  20. Spectroscopic study of gold nanoparticle formation through high intensity laser irradiation of solution

    SciTech Connect

    Nakamura, Takahiro Sato, Shunichi; Herbani, Yuliati; Ursescu, Daniel; Banici, Romeo; Dabu, Razvan Victor

    2013-08-15

    A spectroscopic study of the gold nanoparticle (NP) formation by high-intensity femtosecond laser irradiation of a gold ion solution was reported. The effect of varying energy density of the laser on the formation of gold NPs was also investigated. The surface plasmon resonance (SPR) peak of the gold nanocolloid in real-time UV-visible absorption spectra during laser irradiation showed a distinctive progress; the SPR absorption peak intensity increased after a certain irradiation time, reached a maximum and then gradually decreased. During this absorption variation, at the same time, the peak wavelength changed from 530 to 507 nm. According to an empirical equation derived from a large volume of experimental data, the estimated mean size of the gold NPs varied from 43.4 to 3.2 nm during the laser irradiation. The mean size of gold NPs formed at specific irradiation times by transmission electron microscopy showed the similar trend as that obtained in the spectroscopic analysis. From these observations, the formation mechanism of gold NPs during laser irradiation was considered to have two steps. The first is a reduction of gold ions by reactive species produced through a non-linear reaction during high intensity laser irradiation of the solution; the second is the laser fragmentation of produced gold particles into smaller pieces. The gold nanocolloid produced after the fragmentation by excess irradiation showed high stability for at least a week without the addition of any dispersant because of the negative charge on the surface of the nanoparticles probably due to the surface oxidation of gold nanoparticles. A higher laser intensity resulted in a higher efficiency of gold NPs fabrication, which was attributed to a larger effective volume of the reaction.

  1. An X-ray and Optical Spectroscopic Study of the Perplexing Star RZ Piscium

    NASA Astrophysics Data System (ADS)

    Punzi, Kristina Marie; Kastner, Joel H.; Melis, Carl; Zuckerman, Ben M.

    2017-01-01

    The evolutionary status of the "anti-flare" variable star RZ Psc is ambiguous; both pre- and post-main sequence models have been proposed. RZ Psc shows evidence for gaseous and dusty circumstellar material in the form of emission lines and an infrared excess; its space velocities suggest that it is young, but it does not appear to be a member of a known association of young stars. We report the results of X-ray observations of RZ Psc with XMM-Newton, as well as high-resolution optical spectroscopy of the star obtained at the Lick and Keck observatories. The XMM-Newton imaging spectroscopy establishes that RZ Psc is highly X-ray-luminous, while the optical spectroscopy confirms that the star is G-type and has low surface gravity. The nearly saturated stellar activity and X-ray plasma properties of RZ Psc are indicative of pre-main sequence status, but are also consistent with those of rapidly rotating first-ascent giants. The optical spectroscopy yields evidence for radial velocity variability, hinting at the possibility that RZ Psc is a spectroscopic binary system. Further observations of RZ Psc and its field are necessary to break the age degeneracy and to confirm its close binary status. This research is supported in part by NASA Astrophysics Data Analysis program grant NNX16AG13G to RIT.

  2. Synthesis, crystal structure, spectroscopic properties, antibacterial activity and theoretical studies of a novel difunctional acylhydrazone

    NASA Astrophysics Data System (ADS)

    Jin, Yan-Xian; Zhong, Ai-Guo; Zhang, Yu-jian; Pan, Fu-You

    2011-09-01

    A novel difunctional acylhydrazone has been synthesized by the reaction of 5-methylisoxazole-4-carboyl hydrazine with benzaldehyde and characterized by X-ray crystallography and spectroscopy. The obtained results demonstrate the crystal belongs to triclinic, space group P1¯. Moreover, the spectroscopic properties were evaluated through density functional theory (DFT) and time-dependent density functional theory (TD DFT) calculations. The results reveal that UV-Vis absorption peaks at 194, 217.5 and 290.5 nm are mainly attributed to (p, π) → π ∗, partly (p, π) → π ∗ and partly π → π ∗, and predominantly π → π ∗, respectively, with intraligand charge-transfer transition (ILCT) character. The fluorescence emission peak at 485.96 nm should be assigned to ILCT. In addition, the results of antibacterial activities indicate the title compound has certain modest antibacterial activity as well as the broad-spectrum bacteriostasis, which can be supported by the molecular electrostatic potential (MEP). Therefore, the title compound exhibits both antibacterial activity and photoluminescent property, which has potential applications in many fields such as material science and photodynamic therapy.

  3. Dynamics-function correlation in Cu, Zn superoxide dismutase: a spectroscopic and molecular dynamics simulation study.

    PubMed Central

    Falconi, M; Stroppolo, M E; Cioni, P; Strambini, G; Sergi, A; Ferrario, M; Desideri, A

    2001-01-01

    A single mutation (Val29-->Gly) at the subunit interface of a Cu, Zn superoxide dismutase dimer leads to a twofold increase in the second order catalytic rate, when compared to the native enzyme, without causing any modification of the structure or the electric field distribution. To check the role of dynamic processes in this catalytic enhancement, the flexibility of the dimeric protein at the subunit interface region has been probed by the phosphorescence and fluorescence properties of the unique tryptophan residue. Multiple spectroscopic data indicate that Trp83 experiences a very similar, and relatively hydrophobic, environment in both wild-type and mutant protein, whereas its mobility is distinctly more restrained in the latter. Molecular dynamics simulation confirms this result, and provides, at the molecular level, details of the dynamic change felt by tryptophan. Moreover, the simulation shows that the loops surrounding the active site are more flexible in the mutant than in the native enzyme, making the copper more accessible to the incoming substrate, and being thus responsible for the catalytic rate enhancement. Evidence for increased, dynamic copper accessibility also comes from faster copper removal in the mutant by a metal chelator. These results indicate that differences in dynamic, rather than structural, features of the two enzymes are responsible for the observed functional change. PMID:11371434

  4. Vibrational spectroscopic study of polymorphism and polymorphic transformation of the anti-viral drug lamivudine.

    PubMed

    Du, Yong; Zhang, Huili; Xue, Jiadan; Tang, Wenjian; Fang, Hongxia; Zhang, Qi; Li, Yafang; Hong, Zhi

    2015-02-25

    Vibrational spectra of hydrated and anhydrous lamivudines, and also the dynamic process of polymorphic transformation have been characterized by Fourier transform infrared (FT-IR) and Raman spectroscopic techniques. The vibrational modes of both polymorphic lamivudines are assigned. FT-IR and Raman spectral results show that the interaction between crystalline water and lamivudine molecular has an important effect on the molecular vibration motions of polymorphic lamivudines. The two characteristic Raman peaks at 783 and 798 cm(-1) represent hydrated and anhydrous lamivudine respectively. The relationship between changes of two characteristic peak normalized areas and heating time could be fitted with single exponential functions, and the dynamic information of polymorphic transformation of lamivudine drug is obtained. The decay rate of characteristic peak for hydrated lamivudine and the growth rate of that for anhydrous lamivudine are consistent during dehydration transformation process. The reported results provide us important benchmark for qualitatively monitoring different polymorphic drugs and also establishing the corresponding model for the polymorphic transformation of drugs in related pharmaceutical research fields.

  5. Vibrational spectroscopic study of polymorphism and polymorphic transformation of the anti-viral drug lamivudine

    NASA Astrophysics Data System (ADS)

    Du, Yong; Zhang, Huili; Xue, Jiadan; Tang, Wenjian; Fang, Hongxia; Zhang, Qi; Li, Yafang; Hong, Zhi

    2015-02-01

    Vibrational spectra of hydrated and anhydrous lamivudines, and also the dynamic process of polymorphic transformation have been characterized by Fourier transform infrared (FT-IR) and Raman spectroscopic techniques. The vibrational modes of both polymorphic lamivudines are assigned. FT-IR and Raman spectral results show that the interaction between crystalline water and lamivudine molecular has an important effect on the molecular vibration motions of polymorphic lamivudines. The two characteristic Raman peaks at 783 and 798 cm-1 represent hydrated and anhydrous lamivudine respectively. The relationship between changes of two characteristic peak normalized areas and heating time could be fitted with single exponential functions, and the dynamic information of polymorphic transformation of lamivudine drug is obtained. The decay rate of characteristic peak for hydrated lamivudine and the growth rate of that for anhydrous lamivudine are consistent during dehydration transformation process. The reported results provide us important benchmark for qualitatively monitoring different polymorphic drugs and also establishing the corresponding model for the polymorphic transformation of drugs in related pharmaceutical research fields.

  6. The study of polymers in geometrically confined states by the thermal analysis, the spectroscopic study, and the morphological investigation

    NASA Astrophysics Data System (ADS)

    Lu, Xiaolin

    2005-07-01

    This thesis focuses on the study of the different geometrically confined states of polyacrylamide (PAL) in bulk film, single chain globules, and thin films. The thermal analysis, the spectroscopic study, and the morphological investigation were carried out. The main contribution of this thesis is that we have acquired a better understanding about the glass transition (T g) behavior of polymers. Although the glass transition is a well known phenomenon for liquids with strong covalently bonded structures, and is especially noteworthy for amorphous polymers, understanding the glass transition still remains one of the most intriguing puzzles in condensed matter physics at present. The solution of the glass transition puzzle will ultimately influence different fields in polymer science, particularly biophysics and biochemistry. Our approach to this complicated assignment, the glass transition phenomenon, is to examine the glass transition behavior of polymer chains in 3 dimensional confinement for single molecular single chain globules, 1 dimensional confinement for polymer thin films, and 0 dimensional confinement for bulk state polymer. We found that the glass transition temperature of a polymer depends on several factors, such as the inter-chain interlock entanglement, the inter-chain molecular interactions, the intra-chain cohesional entanglement, and the local chain orientation and conformational entropy. These factors have been systematically investigated by carefully preparing the polymer samples in different confined states. The main conclusion is that, although the glass transition is a non-equilibrium dynamic property, the true glass transition can be reached when polymer chains are free of the inter-chain entanglement. A better example is illustrated, in this thesis, of the glass transition behavior for the well-annealed single chain globules. PAL single chain globules are prepared by spray drying from the dilute solution. The size and morphology of the

  7. The spectroscopic study of simple polyatomic molecules by synchrotron and laser irradiation

    NASA Astrophysics Data System (ADS)

    Kaminski, Lech

    This thesis describes the spectroscopic study of simple poly-atomic molecules, for example NO and Cl2O by UV radiation derived from synchrotron and laser sources. Synchrotron studies were carried out at the Daresbury Laboratory Synchrotron Radiation Source, and the laser studies performed at University College London. The thesis is composed of six chapters. The first chapter discusses molecular structure; UV absorption of photons by simple molecules and describes the modern techniques of Resonance Enhanced Multi Photon Ionisation (REMPI) and Laser Induced Fluorescence (LIF) processes. Chapter two describes the apparatus and the experimental techniques developed during this project at the Daresbury Laboratory Synchrotron Radiation Source. Details are given on the different photoabsorption cells that were built and used, as well as details of synthesis plants used to create short lived molecules of particular importance to atmospheric chemistry, for example N2O5. Chapter three gives a full description of the laser system constructed to study REMPI and LIF processes. The data collection and experimental methodology of the final experimental configuration to study REMPI phenomena is also detailed. Chapter four describes the results obtained by photoabsorption studies for the atmospheric nitrogen and chlorine oxides (Cl2O, N2O5 and ClONO2) Chapter five gives an overview of the results obtained by photoabsorption studies of Polycyclic Aromatic Hydrocarbons. Chapter six presents conclusions of the current work and discusses future experiments that may be undertaken in the apparatus developed during this PhD program.

  8. Spectroscopic and molecular docking studies on the interaction of troxerutin with DNA.

    PubMed

    Subastri, A; Ramamurthy, C H; Suyavaran, A; Mareeswaran, R; Lokeswara Rao, P; Harikrishna, M; Suresh Kumar, M; Sujatha, V; Thirunavukkarasu, C

    2015-01-01

    Troxerutin (TXER) is a derivative of naturally occurring bioflavonoid rutin. It possesses different biological activities in rising clinical world. The biological activity possessed by most of the drugs mainly targets on macromolecules. Hence, in the current study we have examined the interaction mechanism of TXER with calf thymus DNA (CT-DNA) by using various spectroscopic methods, isothermal titration calorimetry (ITC) and molecular docking studies. Further, DNA cleavage study was carried out to find the DNA protection activity of TXER. UV-absorption and emission spectroscopy showed low binding constant values via groove binding. Circular dichroism study indicates that TXER does not modify native B-form of DNA, and it retains the native B-conformation. Furthermore, no effective positive potential peak shift was observed in TXER-DNA complex during electrochemical analysis by which it represents an interaction of TXER with DNA through groove binding. Molecular docking study showed thymine guanine based interaction with docking score -7.09 kcal/mol. This result was compared to experimental ITC value. The DNA cleavage study illustrates that TXER does not cause any DNA damage as well as TXER showed DNA protection against hydroxyl radical induced DNA damage. From this study, we conclude that TXER interacts with DNA by fashion of groove binding.

  9. Jarosite occurrence in the Deccan Volcanic Province of Kachchh, western India: Spectroscopic studies on a Martian analog locality

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Satadru; Mitra, Souvik; Gupta, Saibal; Jain, Nirmala; Chauhan, Prakash; Parthasarathy, G.; Ajai

    2016-03-01

    The sulfate mineral jarosite is considered a key indicator of hydrous, acidic, and oxidizing conditions on the surface of early Mars. Here we report an analog terrestrial locality hosting jarosite from Matanumadh, Kachchh, western India, using detailed spectroscopic studies on weathered basalts of the Deccan Volcanic Province and overlying tuffaceous shales and sandstones of the Matanumadh Formation. Hyperspectral data in the visible/near-infrared (350-2500 nm) to midinfrared (4000-400 cm-1) region of the electromagnetic spectrum and X-ray diffraction patterns have been acquired on samples collected from the field to detect and characterize the hydrous sulfate and phyllosilicate phases present at the studied site. Hydrous sulfates occur in association with Al-rich phyllosilicates (kaolinite) that overlie a zone of Fe/Mg smectites in altered basalts. Jarosite is found within both saprolitic clay horizons altered from the basalt and within variegated sandstone and shale/clay units overlying the saprolite; it mostly occurs as secondary veins with or without gypsum. Jarosite is also seen as coatings on kaolinite clasts of varying shapes and sizes within the tuffaceous variegated sandstone unit. We argue that the overall geological setting of the Matanumadh area, with this unusual mineral assemblage developing within altered basalts and in the overlying sedimentary sequence, mimics the geological environment of many of the identified jarosite localities on Mars and can be considered as a Martian analog from this perspective.

  10. The role of interactions in galaxy evolution: A new perspective from the CALIFA and MaNGA Integral Field Spectroscopic surveys.

    NASA Astrophysics Data System (ADS)

    Barrera-Ballesteros, J. K.; Sanchez, S. F.; Califa Collaboration

    2016-06-01

    Interactions and mergers have been playing a paramount role to understand how galaxies evolve. In recent years integral field spectroscopic (IFS) observations have become routinely allowing researchers to conduct large IFS surveys. In this context, these surveys are providing a new observational scenario to probe the properties of galaxies at different stages of the interaction —from close pairs to post-merger galaxies. Even more, these surveys also include homogeneous observations of non-interacting galaxies which in turns allows to distinguish the processes induce by secular evolution from those driven by interactions. In this talk, We review the studies of interacting studies from the CALIFA survey. They consider from the thorough analysis of a single interactive systems (e.g., the Mice, Wild et al. 2014) to the the statistical study of physical properties of a large sample of interacting/merging galaxies such as their internal structure via their stellar and gas line-of-sight kinematic maps (Barrera-Ballesteros et al. 2015a) or the spatial distribution of the star-forming gas in these galaxies (Barrera-Ballesteros et al. 2015b). Then we present some of the on-going studies within the MaNGA survey. Due to its statistical power (sample size ~10000 objects), this survey will allow us to probe the properties of galaxies in a wide range of the interaction-parameter space. This in turn provides a unique view on the key parameters that affect the internal structure and properties of galaxies during the interaction and subsequent merger.

  11. Structural and spectroscopic studies on Er3+ doped boro-tellurite glasses

    NASA Astrophysics Data System (ADS)

    Selvaraju, K.; Marimuthu, K.

    2012-04-01

    Er3+ doped boro-tellurite glasses with the chemical composition (69-x)B2O3-xTeO2-15MgO-15K2O-1Er2O3 (where x=0, 10, 20, 30 and 40 wt%) have been prepared and their structural and spectroscopic behavior were studied and reported. The varying tellurium dioxide content in the host matrix that results, changes in structural and spectroscopic behavior around Er3+ ions are explored through XRD, FTIR, UV-VIS-NIR and luminescence measurements. The XRD pattern confirms the amorphous nature of the prepared glasses and the FTIR spectra explore the fundamental groups and the local structural units in the prepared boro-tellurite glasses. The bonding parameters (βbar and δ) have been calculated from the observed band positions of the absorption spectra to claim the ionic/covalent nature of the prepared glasses. The Judd-Ofelt (JO) intensity parameters Ωλ (λ=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from the absorption spectra and their results are studied and compared with reported literature. The variation in the JO parameters Ωλ (λ=2, 4 and 6) with the change in chemical composition have been discussed in detail. The JO parameters have also been used to derive the important radiative properties like transition probability (A), branching ratio (βR) and peak stimulated emission cross-section (σPE) for the excited state transitions 2H9/2→4I15/2 and 2H11/2 and 4S3/2→4I15/2 of the Er3+ ions and the results were studied and reported. Using Davis and Mott theory, optical band gap energy (Eopt) values for the direct and indirect allowed transitions have been calculated and discussed along with the Urbach energy values for the prepared Er3+ doped boro-tellurite glasses in the present study. The optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar results.

  12. Static and time-resolved spectroscopic studies of low-symmetry Ru(II) polypyridyl complexes

    SciTech Connect

    Curtright, A.E.; McCusker, J.K.

    1999-09-02

    The spectroscopic and electrochemical properties of a series of four Ru{sup II} polypyridyl complexes are reported. Compounds of the form [Ru(dmb){sub x}(dea){sub 3{minus}x}]{sup 2+} (x = 0--3), where dmb is 4,4{prime}-dimethyl-2,2{prime}-bipyridine and dea is 4,4{prime}-bis(diethylamino)-2,2{prime}-bipyridine, have been prepared and studied using static and time-resolved electronic and vibrational spectroscopies as a prelude to femtosecond spectroscopic studies of excited-state dynamics. Static electronic spectra in CH{sub 3}CN solution reveal a systematic shift of the MLCT absorption envelope from a maximum of 458 nm in the case of [Ru(dmb){sub 3}]{sup 2+} to 518 nm for [Ru(dea){sub 3}]{sup 2+} with successive substitutions of dea for dmb, suggesting a dea-based chromophore as the lowest-energy species. However, analysis of static and time-resolved emission data indicates an energy gap ordering of [Ru(dmb){sub 3}]{sup 2+} > [Ru(dmb){sub 2}(dea)]{sup 2+} > [Ru(dea){sub 3}]{sup 2+} > [Ru(dmb)(DEA){sub 2}]{sup 2+}, at variance with the electronic structures inferred from the absorption spectra. Nanosecond time-resolved electronic absorption and time-resolved step-scan infrared data are used to resolve this apparent conflict and confirm localization of the long-lived {sup 3}MLCT state on dmb in all three complexes where this ligand is present, thus making the dea-based excited state unique to [Ru(dea){sub 3}]{sup 2+}. Electrochemical studies further reveal the origin of this result, where a strong influence of the dea ligand on the oxidative Ru{sup II/III} couple, due to {pi} donation from the diethylamino substituent, is observed. The electronic absorption spectra are then reexamined in light of the now well-determined excited-state electronic structure. The results serve to underscore the importance of complete characterization of the electronic structures of transition metal complexes before embarking on ultrafast studies of their excited-state properties.

  13. UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.

    PubMed

    Farrugia, Kristina N; Makuc, Damjan; Podborska, Agnieszka; Szaciłowski, Konrad; Plavec, Janez; Magri, David C

    2015-02-14

    Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9 : 1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported.

  14. Spectroscopic Terahertz Imaging at Room Temperature Employing Microbolometer Terahertz Sensors and Its Application to the Study of Carcinoma Tissues

    PubMed Central

    Kašalynas, Irmantas; Venckevičius, Rimvydas; Minkevičius, Linas; Sešek, Aleksander; Wahaia, Faustino; Tamošiūnas, Vincas; Voisiat, Bogdan; Seliuta, Dalius; Valušis, Gintaras; Švigelj, Andrej; Trontelj, Janez

    2016-01-01

    A terahertz (THz) imaging system based on narrow band microbolometer sensors (NBMS) and a novel diffractive lens was developed for spectroscopic microscopy applications. The frequency response characteristics of the THz antenna-coupled NBMS were determined employing Fourier transform spectroscopy. The NBMS was found to be a very sensitive frequency selective sensor which was used to develop a compact all-electronic system for multispectral THz measurements. This system was successfully applied for principal components analysis of optically opaque packed samples. A thin diffractive lens with a numerical aperture of 0.62 was proposed for the reduction of system dimensions. The THz imaging system enhanced with novel optics was used to image for the first time non-neoplastic and neoplastic human colon tissues with close to wavelength-limited spatial resolution at 584 GHz frequency. The results demonstrated the new potential of compact RT THz imaging systems in the fields of spectroscopic analysis of materials and medical diagnostics. PMID:27023551

  15. Photoacoustic and dielectric spectroscopic studies of 4-dimethylamino-n-methyl-4-stilbazolium tosylate single crystal: An efficient terahertz emitter

    NASA Astrophysics Data System (ADS)

    Manivannan, M.; Martin Britto Dhas, S. A.; Jose, M.

    2016-12-01

    Bulk terahertz emitting single crystal of 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) was synthesized by condensation method and grown by slow solvent evaporation technique from methanol. The structure and cell parameters of the grown crystals were derived from single crystal and powder X-ray diffraction analyses and the optical properties of the crystal were analyzed by UV-Vis Spectrophotometer. The presence of functional groups was identified by FTIR and FT-Raman spectroscopic studies. We demonstrated that in DAST crystal, the thermal transport properties such as thermal conductivity, thermal diffusivity and thermal effusivity are better than several well recognized standard materials using photoacoustic spectrophotometer. The dielectric measurement was made as a function of frequency (1 Hz-35 MHz) at different temperatures (30-200 °C). The dielectric constant and dielectric loss were found to be strongly dependent on temperature and frequency of the applied electric field. The semicircle in the cole-cole plot showed the presence of dielectric relaxation in the crystal with its diameter representing the resistance of the crystal. The resistivity and ac conductivity were calculated from the measured dielectric data.

  16. Mid Infrared Near Field Study of Monolayer Graphene

    NASA Astrophysics Data System (ADS)

    Fei, Z.; Andreev, G. O.; Bao, W.; Zhang, L. M.; Zhao, Z.; Dominguez, G.; Thiemens, M.; Fogler, M. M.; Lau, C. N.; Keilmann, F.; Basov, D. N.

    2011-03-01

    We have performed near-field spectroscopic studies of both monolayer suspended graphene (SG) and graphene on Si O2 /Si substrate (GOS) using scattering-type scanning near-field optical microscope (s-SNOM). Our data show that SG produces reliable near-field signal in mid-infrared frequencies. Images taken with high spatial resolution (~ 20 nm) show nanoscopic features such as ripples and electronic inhomogeneities. The Si O2 /Si substrate contributes a phonon resonance in the near-field signal around 1130 cm-1 . This resonance is remarkably strengthened and broadened by just a single layer of graphene in the case of GOS. By probing the resonance spectrum we find over 400% contrast in near field signal between GOS and the bare substrate. The detailed analysis of the contrast suggests that GOS is slightly doped. This study therefore provides much needed insight into the thickness resolution of the s-SNOM technique, proving it can be sensitive to just a single layer of atoms, and advances the fundamental understanding of graphene-light interactions by probing in the near-field regime.

  17. High-pressure Raman spectroscopic study of magnetite Fe3O4

    NASA Astrophysics Data System (ADS)

    Kyono, A.; Ahart, M.; Yamanaka, T.; Mysen, B.; Mao, H.; Hemley, R. J.

    2010-12-01

    We report in situ Raman spectroscopic studies of magnetite in a diamond-anvil cell under hydrostatic conditions up to 60 GPa at room temperature. Magnetite with ideal chemical formula Fe3O4 crystallizes in the face-centered cubic spinel-type structure. There are five first-order Raman active modes (A1g + Eg + 3F2g) in the Fd3m space group of the spinel structure. Three modes at nearby 300, 600 and 700 cm-1 are observed under pressure conditions. In the cubic spinels including ferrites, the highest frequency at about 700 cm-1 corresponds to the stretching vibrations of oxygen atoms in the tetrahedral coordination and can be assigned to the A1g symmetry. The other strong peak centered at about 600 and 300 cm-1 can be assigned to the F2g and Eg symmetries. The remaining two modes could not be observed unambiguously in the measurements. The peak positions and shapes of the Raman spectra agree well with previously published data measured under ambient condition. With increasing pressure, the frequencies of the two modes A1g , F2g and Eg increase continuously up to about 30 GPa with pressure derivatives of 2.7, 4.5 and 1.4 cm-1/GPa, respectively. There is no obvious degradation of crystal symmetry or structural change within this pressure range. Upon elevation of pressure to nearby 30 GPa, the F2g mode starts to display a variation in the spectra and its intensity gradually decreases due to the tetragonal-orthorhombic phase transition. The splitted mode into B1g, B2g, B3g from F2g completely disappears at a pressure of 40 GPa. The most striking characteristic of Raman spectroscopy of magnetite is that the pressure-induced suppression leads to a significant extinction of the Raman active mode derived from F2g symmetry. Only one peak resulting from A1g mode can be observed continuously up to 60 GPa. Consequently, the results of the Raman spectroscopic study about phase transformation are in good agreement with that of the X-ray diffraction study.

  18. Spectroscopic and molecular modeling studies on the interactions of N-Methylformamide with superoxide dismutase.

    PubMed

    Kalyani, Durai; Jyothi, Kanagaraj; Sivaprakasam, Chinnarasu; Nachiappan, Vasanthi

    2014-04-24

    N-Methylformamide, a polar solvent has a wide industrial applications and it is well-known for hepatotoxicity. The interaction between NMF with superoxide dismutase, an antioxidant defense enzyme has been studied for the first time using spectroscopic methods including Fourier transform infrared (FT-IR) spectroscopy, Circular dichroism (CD) spectroscopy and UV-visible spectroscopy under simulative physiological conditions and also by molecular modelling. Fourier Transform Infra Red analysis showed that the change in peak positions and shapes revealed that the secondary structure of SOD had been changed by the interaction with NMF. The data of CD spectra also confirmed that NMF decreased the degree of secondary structure of SOD, which directly resulted in destabilization of enzyme. We studied the inhibitory effect of NMF on enzyme kinetics by pyrogallol autoxidation revealed that protein-ligand complex caused structural unfolding which resulted in enzymatic inhibition. Thus the spectral behaviour of superoxide dismutase provides data concerning its conformational changes in the presence of NMF. Furthermore, molecular docking was applied to explore the binding mode between the protein-ligand complex. This suggested that Asn54 and Val302 residues of dimeric protein were predicted to interact with NMF. The present study provides direct evidence at a molecular level to show that exposure to NMF cause perturbation in its structure and function.

  19. Spectroscopic and structural studies of allyl urethane derivative of Monensin A sodium salt

    NASA Astrophysics Data System (ADS)

    Huczyński, Adam; Janczak, Jan; Brzezinski, Bogumil; Bartl, Franz

    2013-07-01

    A new derivative of polyether antibiotic Monensin A sodium salt its allyl urethane (MON-UR2-Na) was synthesised and its structure was studied by X-ray, FT-IR, NMR, and ESI-MS methods. The results of these studies demonstrated that the oxygen atom of the Cdbnd O urethane group is not engaged in the coordination of the Na+ as postulated previously. The crystal space group is P21 with a = 12.0378(11), b = 12.4495(11), c = 14.9690(14), β = 94.791(8) and Z = 2. The structure determined in the present study exhibits significant differences with respect to the earlier published structure of phenyl urethane of Monensin. A comparison of these structures clearly shows that not only the functional urethane group but also its substituent strongly influence the structure of this type of derivatives of Monensin A. X-ray data and spectroscopic and spectrometric behaviour of the new derivative of Monensin A are discussed in detail and compared to the structure of phenyl urethane of Monensin A sodium salt.

  20. Raman spectroscopic study of keratin 8 knockdown oral squamous cell carcinoma derived cells

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Alam, Hunain; Dmello, Crismita; Vaidya, Milind M.; Krishna, C. Murali

    2012-03-01

    Keratins are one of most widely used markers for oral cancers. Keratin 8 and 18 are expressed in simple epithelia and perform both mechanical and regulatory functions. Their expression are not seen in normal oral tissues but are often expressed in oral squamous cell carcinoma. Aberrant expression of keratins 8 and 18 is most common change in human oral cancer. Optical-spectroscopic methods are sensitive to biochemical changes and being projected as novel diagnostic tools for cancer diagnosis. Aim of this study was to evaluate potentials of Raman spectroscopy in detecting minor changes associated with differential level of keratin expression in tongue-cancer-derived AW13516 cells. Knockdown clones for K8 were generated and synchronized by growing under serum-free conditions. Cell pellets of three independent experiments in duplicate were used for recording Raman spectra with fiberoptic-probe coupled HE-785 Raman-instrument. A total of 123 and 96 spectra from knockdown clones and vector controls respectively in 1200-1800 cm-1 region were successfully utilized for classification using LDA. Two separate clusters with classification-efficiency of ~95% were obtained. Leave-one-out cross-validation yielded ~63% efficiency. Findings of the study demonstrate the potentials of Raman spectroscopy in detecting even subtle changes such as variations in keratin expression levels. Future studies towards identifying Raman signals from keratin in oral cells can help in precise cancer diagnosis.

  1. Binding characteristics of psoralen with trypsin: Insights from spectroscopic and molecular modeling studies.

    PubMed

    Liu, Yingying; Zhang, Guowen; Liao, Yijing; Wang, Yaping

    2015-01-01

    Psoralen (PSO) is a naturally occurring furanocoumarin with a variety of pharmacological activities, however very limited information on the interaction of PSO with trypsin is available. In this study, the binding characteristics between PSO and trypsin at physiological pH were investigated using a combination of fluorescence, UV-vis absorption, circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopic, chemometric and molecular modeling approaches. It was found that the fluorescence quenching of trypsin by PSO was a static quenching procedure, ascribing the formation of a PSO-trypsin complex. The binding of PSO to trypsin was driven mainly by hydrophobic forces as the positive enthalpy change and entropy change values. The molecular docking showed that PSO inserted into the active site pocket of trypsin to interact with the catalytic residues His57, Asp102 and Ser195 and may cause a decrease in trypsin activity. The results of CD and FT-IR spectra along with the temperature-induced denaturation studies indicated that the addition of PSO to trypsin led to the changes in the secondary structure of the enzyme. The concentration profiles and spectra of the three components (PSO, trypsin, and PSO-trypsin complex) obtained by multivariate curve resolution-alternating least squares analysis exhibited the kinetic processes of PSO-trypsin interaction. This study will be helpful to understand the mechanism of PSO that affects the conformation and activity of trypsin in biological processes.

  2. Spectroscopic studies on the conformational transitions of a bovine growth hormone releasing factor analog

    NASA Astrophysics Data System (ADS)

    Sarver, Ronald W.; Friedman, Alan R.; Thamann, Thomas J.

    1997-10-01

    The secondary structure of the bovine growth hormone releasing factor analog, [Ile 2, Ser 8,28, Ala 15, Leu 27, Hse 30] bGRF(1-30)-NH-Ethyl, acetate salt (U-90699F) was studied in solution by Fourier transform infrared and Raman spectroscopies. Spectroscopic studies revealed that concentrated aqueous solutions of U-90699F (100 mg ml -1) undergo a secondary structure transition from disordered coil/α-helix to intermolecular β-sheet. Disordered coil and α-helical structure were grouped together in the infrared and Raman studies since the amide I vibrations are close in frequency and overlap in assignments was possible. Before the conformational transition, the facile exchange of the peptide's amide hydrogens for deuterium indicated that the majority of amide hydrogens were readily accessible to solvent. The kinetics of the conformational transition coincided with an increase in solution viscosity and turbidity. An initiation phase preceded the conformational transition during which only minor spectral changes were observed by infrared spectroscopy. The initiation phase and reaction kinetics were consistent with a highly cooperative nucleation ultimately leading to a network of intermolecular β-sheet structure and gel formation. Increased temperature accelerated the conformational transition. The conformational transition was thermally irreversible but the β-sheet structure of aggregated or gelled peptide could be disrupted by dilution and agitation.

  3. Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

    SciTech Connect

    Arora, V.; Chakera, J. A.; Naik, P. A.; Gupta, P. D.

    2015-07-31

    X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available for time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.

  4. The effect of refluxing on the alkoxide-based sodium potassium niobate sol-gel system: Thermal and spectroscopic studies

    SciTech Connect

    Chowdhury, Anirban; Bould, Jonathan; Londesborough, Michael G.S.; Milne, Steven J.

    2011-02-15

    A study on the effects of prolonged heating under reflux conditions of up to 70 h on alkoxides of sodium, potassium and niobium dissolved in 2-methoxyethanol for the synthesis of sols of composition Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) has been carried out using combined thermogravimetric-Fourier transform infrared spectroscopic analyses. Extended refluxing increases the homogeneity of the Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) system. Spectroscopic analyses on the non-refluxed and 70 h refluxed NKN gels reveal the existence of inorganic hydrated carbonates and bicarbonates, which we propose arise from the hydration and carbonation of the samples on standing in air. The X-ray diffraction patterns of these two types of gels show orthorhombic NKN phase evolutions at higher temperatures. -- Graphical abstract: Total organic evolution plots over time for NKN dried gels obtained under different refluxing times show different thermochemical behaviours and these were investigated by thermal and spectroscopic analysis tools to find a correlation between the extent of -M-O-M- chain link formation and the amount of solvent vapour (methoxyethanol) evolution. Display Omitted Research highlights: > Prolonged refluxing of sol-gel NKN precursor solutions improves final properties of an NKN system. > An NKN process thermo-chemistry with thermal and spectroscopic analysis tools was explored. > An FTIR of NKN gels reveals tendency of NKN systems for rehydration and recarbonation on standing.

  5. Spectroscopic study of humic acids fractionated by means of tangential ultrafiltration

    NASA Astrophysics Data System (ADS)

    Francioso, O.; Sánchez-Cortés, S.; Casarini, D.; Garcia-Ramos, J. V.; Ciavatta, C.; Gessa, C.

    2002-05-01

    Different chemical and spectroscopic techniques—diffuse reflectance infrared Fourier transform (DRIFT), surface-enhanced Raman spectroscopy (SERS), and 1H, 13C nuclear magnetic resonance (NMR) have been applied to investigate a peat humic acid (HA) separated by tangential ultrafiltration into different nominal molecular weight (NMW) fractions. Each fraction analyzed showed a characteristic DRIFT and NMR pattern. High nominal molecular weight fractions were mainly characterized by long chains of methyl and methylene groups and poorly substituted aromatic rings, while in low nominal molecular weight fractions (L-NMW), phenolic and oxygen-containing groups were predominant. A comparative study on fractions before and after treatment with 0.5 M HCl was carried out. Purified fractions showed either an increase in the carboxylate and phenolic OH groups or an improvement in signal-to-noise ratio of their NMR spectra. The SERS study of NMW fractions allowed significative information on structure and conformation of these fractions. In particular, L-NMW fractions showed a great structural modification, when different alkaline extractants or treatment with HCl were used. Humic-like substances obtained by catechol and gallic acid polymerization on metal surface were investigated using SERS. The SERS spectra of these polymers were compared and discussed with those of NMW HA fractions.

  6. Mechanism and conformational studies of farrerol binding to bovine serum albumin by spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Zhang, Guowen; Wang, Lin; Fu, Peng; Hu, Mingming

    2011-11-01

    The mechanism and conformational changes of farrerol binding to bovine serum albumin (BSA) were studied by spectroscopic methods including fluorescence quenching technique, UV-vis absorption, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy under simulative physiological conditions. The results of fluorescence titration revealed that farrerol could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The thermodynamic parameters enthalpy change and entropy change for the binding were calculated to be -29.92 kJ mol -1 and 5.06 J mol -1 K -1 according to the van't Hoff equation, which suggested that the both hydrophobic interactions and hydrogen bonds play major role in the binding of farrerol to BSA. The binding distance r deduced from the efficiency of energy transfer was 3.11 nm for farrerol-BSA system. The displacement experiments of site markers and the results of fluorescence anisotropy showed that warfarin and farrerol shared a common binding site I corresponding to the subdomain IIA of BSA. Furthermore, the studies of synchronous fluorescence, CD and FT-IR spectroscopy showed that the binding of farrerol to BSA induced conformational changes in BSA.

  7. Synthesis, structural and spectroscopic studies of 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide

    NASA Astrophysics Data System (ADS)

    Henriques, M. S. C.; Del Amparo, R.; Pérez-Álvarez, D.; Nogueira, B. A.; Rodríguez-Argüelles, M. C.; Paixão, J. A.

    2017-02-01

    The synthesis of a new hydrazone, 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide, and its structural and spectroscopic characterization is reported. The obtained powder was recrystallized from DMSO and ethanol that afforded small crystals used for single-crystal X-ray diffraction studies. The compound was found to crystallize in two polymorphs, depending on the crystallization conditions. One of the polymorphs (form I) crystallizes in the centrosymmetric P21/c monoclinic space group, the other (form II) crystallizes in the non-centrosymmetric, but achiral, orthorhombic space group P212121. Conformation of the molecules is similar in both polymorphs, but the network of weak intermolecular interactions determining the crystal packing is different. In form II an additional C-H⋯O bond connects molecules related by the screw-axis running parallel to the a-axis. Crystals of both polymorphs were also screened by FT-IR and Raman microscopy; a detailed analysis of the spectra and comparison with those of the isolated molecule calculated by ab-initio HF/MP2 and DFT/B3LYP methods using a correlation consistent cc-pVDZ basis set is presented. In addition, UV-vis and NMR studies were performed in solution.

  8. Hydrogen bonding interactions in nicotinamide Ionic Liquids: A comparative spectroscopic and DFT studies

    NASA Astrophysics Data System (ADS)

    Shukla, Madhulata

    2017-03-01

    Being biodegradable in nature nicotinamide based Ionic Liquids (ILs) are gaining much attention now a day. Nicotinamide iodide (i.e 1-methyl-3ethoxy carbonyl pyridinium iodide (mNicI)) and 1-methyl-3ethoxy carbonyl pyridinium trifilimide (mNicNTf2) new ILs has been synthesized and has been characterized using different spectroscopic techniques like NMR, UV visible and infrared spectroscopy. Theoretical studies have been performed on several nicotinamide ILs. Geometry and spectral features were further characterized by Density Functional Theory (DFT) calculation. NBO charge distribution and electrostatic potential diagram presents in depth knowledge about interactions between cation and anion. A comparative theoretical study between mNicI and its other analogues i. e 1-methyl-3 ethoxy carbonyl pyridinium chloride and bromide i. e mNicCl and mNicBr has also been performed. Csbnd H⋯X hydrogen bonding along with C⋯X interaction has been reported for the first time for the nicotinamide based ILs. C2sbnd H stretching frequency shifts to higher wavenumber with change to a lesser electronegative anion. mNicCl and mNicBr are expected to be solid in nature with the evidence from the red shift in stretching frequency as compared to mNicI. TD-DFT calculation of mNicI proved that pale yellow color of liquid is due to inherent transition from anion to cation.

  9. The systems V(IV)O(2+)-glutathione and related ligands: a potentiometric and spectroscopic study.

    PubMed

    Pessoa, João Costa; Tomaz, Isabel; Kiss, Tamás; Kiss, Erzsébet; Buglyó, Péter

    2002-03-01

    The equilibria in the system V(IV)O(2+)-glutathione in aqueous solution were studied in the pH range 2-11 by a combination of pH-potentiometry and spectroscopy (EPR, visible absorption and circular dichroism). The results of the various methods are consistent and the equilibrium model includes the species MLH(3), MLH(2), MLH, ML(2)H(2), MLH(-1), and MLH(-2) and several hydrolysis products (where H(4)L denotes totally protonated glutathione); individual formation constants and spectra are given. ML(2)H(2) is the predominant species at physiological pH. Plausible structures for each stoichiometry are discussed. The related V(IV)O(2+) systems of S-methylglutathione and gamma- L-glutamyl- L-cysteinyl ethyl ester were studied by means of the same spectroscopic techniques in order to support the established binding modes for the glutathione complexes. The importance of glutathione and oxidized glutathione in binding V(IV)O(2+) in cells is assessed.

  10. Spectroscopic study on binding of gentisic acid to bovine serum albumin.

    PubMed

    Garzón, Andrés; Bravo, Iván; Carrión-Jiménez, M Rosario; Rubio-Moraga, Ángela; Albaladejo, José

    2015-01-01

    The interaction of (gentisic acid) GA with (bovine serum albumin) BSA has been studied by different spectroscopic techniques. GA is a monoanionic specie at the working pH of 7.4, it was determined by combining UV-Vis absorption spectroscopy and theoretical calculations. A set of fluorescence quenching experiments at different temperatures was carried out employing the native fluorescence of BSA. A Stern-Volmer constant (KSV) of (2.07±0.12)×10(4) mol(-1) L and a binding constant (Ka) of (8.47±4.39)×10(3) were determined at 310 K. The static quenching caused by the BSA-GA complex formation seems to play a significant role in the overall quenching process. A single binding site on BSA for GA was observed. ΔH=-55.6±0.2 kJ mol(-1) and ΔS=-104.3±0.6 J mol(-1) K(-1) were determined in a set of experiments on the dependence of Ka with the temperature. The binding process is, therefore, spontaneous and enthalpy-driven. Van der Waals forces and hydrogen bonds could also play the major role in the binding mode. The secondary structure changes of BSA in the absence and presence of GA were studied by FTIR and UV-Vis absorption spectroscopy.

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

    PubMed

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

    2015-02-05

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

  12. Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study.

    PubMed

    Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

    2016-03-15

    Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation.

  13. Interaction of imatinib mesylate with human serum transferrin: The comparative spectroscopic studies.

    PubMed

    Śliwińska-Hill, Urszula

    2017-02-15

    Imatinib mesylate (Imt) is a tyrosine kinase inhibitor mainly used in the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia (Ph+CML). Human serum transferrin is the most abundant serum protein responsible for the transport of iron ions and many endogenous and exogenous ligands. In this study the mechanism of interactions between the imatinib mesylate and all states of transferrin (apo-Tf, Htf and holo-Tf) has been investigated by fluorescence, ultraviolet-visible (UV-vis), circular dichroism (CD) and zeta potential spectroscopic methods. Based on the experimental results it was proved that under physiological conditions the imatinib mesylate binds to the each form of transferrin with a binding constant c.a. 10(5)M(-1). The thermodynamic parameters indicate that hydrogen bonds and van der Waals were involved in the interaction of apo-Tf with the drug and hydrophobic and ionic strength participate in the reaction of Htf and holo-Tf with imatinib mesylate. Moreover, it was shown that common metal ions, Zn(2+) and Ca(2+) strongly influenced apo-Tf-Imt binding constant. The CD studies showed that there are no conformational changes in the secondary structure of the proteins. No significant changes in secondary structure of the proteins upon binding with the drug and instability of apo-Tf-Imt system are the desirable effects from pharmacological point of view.

  14. Spectroscopic study of the authentic emitter of AMPPD chemiluminescence in alkaline aqueous solution.

    PubMed

    Tu, Langping; Wang, Yu; Yang, Yifei; Bakker, Bert H; Kong, Xianggui; Brouwer, Albert M; Buma, Wybren J; Zhang, Hong

    2010-07-07

    To design more effective CIEEL (chemically initiated electron exchange luminescence) systems demands a complete picture of the dynamics of the chemiluminescence, which is often a challenge. In this work, photoluminescence of the methyl m-oxybenzoate anion - the authentic emitter of AMPPD (3-[2-spiroadamantane]-4-methoxy-4-[3-phosphoryloxy]-phenyl-1,2-dioxetane) in aqueous solvent has been studied. Combining the effect of solvent properties, e.g. pH value, and spectroscopic studies employing steady-state and ultrafast time-resolved emission and absorption and (1)H NMR techniques, a novel mechanism is proposed. We conclude that the deviation of emission peaks between chemiluminescence and photoluminescence of the authentic emitter of AMPPD i.e. the methyl m-oxybenzoate anion, in alkaline aqueous solvents is due to its hydrolysis, rather than the hydrogen-bonding effect as has been assumed so far. Besides, the hydrogen-bonding is suggested to play a key role in significantly decreasing the chemiluminescence yield of AMPPD in aqueous solution by shortening the lifetime of the excited authentic emitter to 10 ps order of magnitude - three orders of magnitude shorter than the previously reported value ( approximately 10 ns). These results shed light on the chemiluminescence dynamics of AMPPD and facilitate the design of more effective CIEEL systems.

  15. Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

    2016-03-01

    Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation.

  16. Optical and spectroscopic studies on tannery wastes as a possible source of organic semiconductors.

    PubMed

    Nashy, El-Shahat H A; Al-Ashkar, Emad; Moez, A Abdel

    2012-02-01

    Tanning industry produces a large quantity of solid wastes which contain hide proteins in the form of protein shavings containing chromium salts. The chromium wastes are the main concern from an environmental stand point of view, because chrome wastes posses a significant disposal problem. The present work is devoted to investigate the possibility of utilizing these wastes as a source of organic semi-conductors as an alternative method instead of the conventional ones. The chemical characterization of these wastes was determined. In addition, the Horizontal Attenuated Total Reflection (HATR) FT-IR spectroscopic analysis and optical parameters were also carried out for chromated samples. The study showed that the chromated samples had suitable absorbance and transmittance in the wavelength range (500-850 nm). Presence of chromium salt in the collagen samples increases the absorbance which improves the optical properties of the studied samples and leads to decrease the optical energy gap. The obtained optical energy gap gives an impression that the environmentally hazardous chrome shavings wastes can be utilized as a possible source of natural organic semiconductors with direct and indirect energy gap. This work opens the door to use some hazardous wastes in the manufacture of electronic devices such as IR-detectors, solar cells and also as solar cell windows.

  17. Studies on the inclusion behavior of 9-Aminoacridine into cyclodextrins: Spectroscopic and theoretical evidences

    NASA Astrophysics Data System (ADS)

    Manivannan, C.; Vijay Solomon, R.; Venuvanalingam, P.; Renganathan, R.

    2013-02-01

    9-Aminoacridine (9-AA) is an important attractive pharmaceutical drug employed as chemotheraptic agent for wound dressings. However, 9-AA possesses limited solubility and rapid metabolic decomposition renders this potential drug to limit its applications. Here we propose cyclodextrins (CDs) as a drug carrier to improve the bioavailability, solubility of 9-AA. The interaction between 9-AA and CDs (α-CD and β-CD) has been studied using UV-Vis absorption, steady state time resolved fluorescence, 1H NMR and FT-IR spectroscopy techniques. The spectroscopic measurements show that 9-AA does not form stable complex with α-CD and also confirmed by DFT calculations. On the other hand, 9-AA forms inclusion complex with β-CD in a 1:1 stoichiometry ratio. Our DFT results suggest that 9-AA stabilizes inside the CD environment through hydrogen bonding that has unambiguously confirmed by AIM analysis. Thus our studies provide a useful insights in the development of Aminoacridine based drugs & its delivery through a suitable carrier like CDs.

  18. Synthesis, structural and spectroscopic studies of 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide.

    PubMed

    Henriques, M S C; Del Amparo, R; Pérez-Álvarez, D; Nogueira, B A; Rodríguez-Argüelles, M C; Paixão, J A

    2017-02-05

    The synthesis of a new hydrazone, 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide, and its structural and spectroscopic characterization is reported. The obtained powder was recrystallized from DMSO and ethanol that afforded small crystals used for single-crystal X-ray diffraction studies. The compound was found to crystallize in two polymorphs, depending on the crystallization conditions. One of the polymorphs (form I) crystallizes in the centrosymmetric P21/c monoclinic space group, the other (form II) crystallizes in the non-centrosymmetric, but achiral, orthorhombic space group P212121. Conformation of the molecules is similar in both polymorphs, but the network of weak intermolecular interactions determining the crystal packing is different. In form II an additional C-H⋯O bond connects molecules related by the screw-axis running parallel to the a-axis. Crystals of both polymorphs were also screened by FT-IR and Raman microscopy; a detailed analysis of the spectra and comparison with those of the isolated molecule calculated by ab-initio HF/MP2 and DFT/B3LYP methods using a correlation consistent cc-pVDZ basis set is presented. In addition, UV-vis and NMR studies were performed in solution.

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

    PubMed

    Shahabadi, Nahid; Falsafi, Monireh; Maghsudi, Maryam

    2017-01-02

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

  20. Interaction of imatinib mesylate with human serum transferrin: The comparative spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Śliwińska-Hill, Urszula

    2017-02-01

    Imatinib mesylate (Imt) is a tyrosine kinase inhibitor mainly used in the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia (Ph + CML). Human serum transferrin is the most abundant serum protein responsible for the transport of iron ions and many endogenous and exogenous ligands. In this study the mechanism of interactions between the imatinib mesylate and all states of transferrin (apo-Tf, Htf and holo-Tf) has been investigated by fluorescence, ultraviolet-visible (UV-vis), circular dichroism (CD) and zeta potential spectroscopic methods. Based on the experimental results it was proved that under physiological conditions the imatinib mesylate binds to the each form of transferrin with a binding constant c.a. 105 M- 1. The thermodynamic parameters indicate that hydrogen bonds and van der Waals were involved in the interaction of apo-Tf with the drug and hydrophobic and ionic strength participate in the reaction of Htf and holo-Tf with imatinib mesylate. Moreover, it was shown that common metal ions, Zn2 + and Ca2 + strongly influenced apo-Tf-Imt binding constant. The CD studies showed that there are no conformational changes in the secondary structure of the proteins. No significant changes in secondary structure of the proteins upon binding with the drug and instability of apo-Tf-Imt system are the desirable effects from pharmacological point of view.

  1. Potentiometric and spectroscopic study of the interaction of 3d transition metal ions with inositol hexakisphosphate

    NASA Astrophysics Data System (ADS)

    Veiga, Nicolás; Macho, Israel; Gómez, Kerman; González, Gabriel; Kremer, Carlos; Torres, Julia

    2015-10-01

    Among myo-inositol phosphates, the most abundant in nature is the myo-inositol hexakisphosphate, InsP6. Although it is known to be vital to cell functioning, the biochemical research into its metabolism needs chemical and structural analysis of all the protonation, complexation and precipitation processes that it undergoes in the biological media. In view of its high negative charge at physiological level, our group has been leading a thorough research into the InsP6 chemical and structural behavior in the presence of the alkali and alkaline earth metal ions essential for life. The aim of this article is to extend these studies, dealing with the chemical and structural features of the InsP6 interaction with biologically relevant 3d transition metal ions (Fe(II), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)), in a non-interacting medium and under simulated physiological conditions. The metal-complex stability constants were determined by potentiometry, showing under ligand-excess conditions the formation of mononuclear species in different protonation states. Under metal ion excess, polymetallic species were detected for Fe(II), Fe(III), Zn(II) and Cu(II). Additionally, the 31P NMR and UV-vis spectroscopic studies provided interesting structural aspects of the strong metal ion-InsP6 interaction.

  2. Theoretical and spectroscopic studies of pyridyl substituted bis-coumarins and their new neodymium (III) complexes

    NASA Astrophysics Data System (ADS)

    Kostova, Irena; Trendafilova, Natasha; Mihaylov, Tzvetan

    2005-07-01

    Ab initio, DFT and spectroscopic studies of 3,3'-( o-pyridinomethylene)di-[4-hydroxycoumarin], 3,3'-( m-pyridinomethylene)di-[4-hydroxycoumarin] and 3,3'-( p-pyridinomethylene)di-[4-hydroxycoumarin] were performed. The molecular and electronic structures of the compounds were investigated using accurate HF and B3LYP/6-31G(d) calculations. Molecular quantities as vertical ionization potential, electron affinity, electronegativity, hardness and electrophilicity indices of the neutral species were calculated and discussed. Molecular electrostatic potential was considered as an additional molecular characteristic for predicting the most probable sites for electrophilic attack. The molecular structure and quantities of the dianionic species, which are active in solution, were calculated and discussed. The theoretical results suggested that both carbonyl and both hydroxyl oxygen atoms are preferred binding sites for electrophilic attack, in particular for a metal coordination. Further, the coordination abilities of the compounds were studied in complexation reactions with Nd(III). Complexes of Nd(III) with o-, m- and p-3,3'-(pyridinomethylene)di-[4-hydroxycoumarin] were synthesized and characterized by different physicochemical methods: elemental analysis, IR, 1H NMR spectroscopies and mass spectral data. The experimental data confirmed the theoretical predictions that the ligands in Nd(III) complexes are tetradentate and bound the metal ion through both carbonyl and both deprotonated hydroxyl oxygen atoms.

  3. Optical and spectroscopic studies on tannery wastes as a possible source of organic semiconductors

    NASA Astrophysics Data System (ADS)

    Nashy, El-Shahat H. A.; Al-Ashkar, Emad; Abdel Moez, A.

    2012-02-01

    Tanning industry produces a large quantity of solid wastes which contain hide proteins in the form of protein shavings containing chromium salts. The chromium wastes are the main concern from an environmental stand point of view, because chrome wastes posses a significant disposal problem. The present work is devoted to investigate the possibility of utilizing these wastes as a source of organic semi-conductors as an alternative method instead of the conventional ones. The chemical characterization of these wastes was determined. In addition, the Horizontal Attenuated Total Reflection (HATR) FT-IR spectroscopic analysis and optical parameters were also carried out for chromated samples. The study showed that the chromated samples had suitable absorbance and transmittance in the wavelength range (500-850 nm). Presence of chromium salt in the collagen samples increases the absorbance which improves the optical properties of the studied samples and leads to decrease the optical energy gap. The obtained optical energy gap gives an impression that the environmentally hazardous chrome shavings wastes can be utilized as a possible source of natural organic semiconductors with direct and indirect energy gap. This work opens the door to use some hazardous wastes in the manufacture of electronic devices such as IR-detectors, solar cells and also as solar cell windows.

  4. Line-Mixing Relaxation Matrix model for spectroscopic and radiative transfer studies

    NASA Astrophysics Data System (ADS)

    Mendaza, Teresa; Martin-Torres, Javier

    2016-04-01

    We present a generic model to compute the Relaxation Matrix easily adaptable to any molecule and type of spectroscopic lines or bands in non-reactive molecule collisions regimes. It also provides the dipole moment of every transition and level population of the selected molecule. The model is based on the Energy-Corrected Sudden (ECS) approximation/theory introduced by DePristo (1980), and on previous Relaxation Matrix studies for the interaction between molecular ro-vibrational levels (Ben-Rueven, 1966), atoms (Rosenkranz, 1975), linear molecules (Strow and Reuter, 1994; Niro, Boulet and Hartmann, 2004), and symmetric but not linear molecules (Tran et al., 2006). The model is open source, and it is user-friendly. To the point that the user only has to select the wished molecule and vibrational band to perform the calculations. It reads the needed spectroscopic data from the HIgh-resolution TRANsmission molecular absorption (HITRAN) (Rothman et al., 2013) and ExoMol (Tennyson and Yurchenko, 2012). In this work we present an example of the calculations with our model for the case of the 2ν3 band of methane (CH4), and a comparison with a previous work (Tran et al., 2010). The data produced by our model can be used to characterise the line-mixing effects on ro-vibrational lines of the infrared emitters of any atmosphere, to calculate accurate absorption spectra, that are needed in the interpretation of atmospheric spectra, radiative transfer modelling and General Circulation Models (GCM). References [1] A.E. DePristo, Collisional influence on vibration-rotation spectral line shapes: A scaling theoretical analysis and simplification, J. Chem. Phys. 73(5), 1980. [2] A. Ben-Reuven, Impact broadening of microwave spectra, Phys. Rev. 145(1), 7-22, 1966. [3] P.W. Rosenkranz, Shape of the 5 mm Oxygen Band in the Atmosphere, IEEE Transactions on Antennas and Propagation, vol. AP-23, no. 4, pp. 498-506, 1975. [4] Strow, L.L., D.D. Tobin, and S.E. Hannon, A compilation of

  5. AN IMAGING AND SPECTROSCOPIC STUDY OF FOUR STRONG Mg II ABSORBERS REVEALED BY GRB 060418

    SciTech Connect

    Pollack, L. K.; Prochaska, J. X.; Chen, H.-W.; Bloom, J. S.

    2009-08-20

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) {approx}> 1 A revealed by the afterglow of GRB 060418 at z{sub GRB} = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z {sub GRB}, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Ly{alpha} systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at {delta} {theta} {approx}< 3.''5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity {approx}0.1 - 1 L{sub *} at impact parameter of {rho} {approx}< 10 h {sup -1} kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of {rho} = 2 - 12 h {sup -1} kpc from the afterglow. At the afterglow's position, we derive a 2{sigma} upper limit to the underlying star-formation rate intensity of 0.0074 M{sub sun} yr{sup -1} kpc

  6. Massive spectroscopic analysis of the stellar populations in three of the CoRoT/Exoplanet fields

    NASA Astrophysics Data System (ADS)

    Gazzano, J.-C.; Deleuil, M.; de Laverny, P.; Kordopatis, G.; Moutou, C.; Recio-Blanco, A.; Bijaoui, A.; Bouchy, F.; Ordenovic, C.

    2010-12-01

    We derived the atmospheric parameters (teff, logg, met, alf), řad, and šini for 1227 CoRoT/Exoplanet targets in three of the fields observed by CoRoT. We derived the corresponding absolute magnitude using evolutionary models. We combined 2MASS colours with a new implementation of the infrared flux method, and the teff from matisse to constrain the interstellar extinction. These steps allowed us to measure the stellar distances, hence deriving kinematics information. This opened the path to the study of the stellar populations found in these \\corot fields.These studies showed the potential of combining a multi-fiber instrument like FLAMES/GIRAFFE, with an automatic tool to determine efficiently atmospheric stellar parameters, as MATISSE.

  7. A Raman Spectroscopic Study of Samples from the May 2001 FIDO Test Site

    NASA Technical Reports Server (NTRS)

    Kuebler, K.; Jolliff, B. L.; Wang, A.; Haskin, L. A.

    2002-01-01

    Last May, a rover field test was conducted in the Mojave desert. This study shows what mineralogy a rover-deployed Raman spectrometer might have observed. Additional information is contained in the original extended abstract.

  8. Spectroscopic studies on the interaction of bovine serum albumin with surfactants and apigenin

    NASA Astrophysics Data System (ADS)

    Zhao, Xu-Na; Liu, Yi; Niu, Li-Yuan; Zhao, Chen-Ping

    The binding of apigenin (Ap) to bovine serum albumin (BSA) has been studied using the methods of fluorescence spectroscopy and UV-vis absorption spectroscopy. The spectroscopic analysis of the quenching mechanism indicates that the quenching constants are inversely correlated with the temperatures and the quenching process could result from a static interaction. The type of interaction force was discussed and the binding site of Ap was in site I (subdomain IIA) of BSA. The thermodynamic parameters ΔH and ΔS are -42.02 kJ mol-1 and -48.31 J mol-1 K-1, respectively and the negative ΔG implying that the binding interaction was spontaneous. The distance r between BSA and Ap was calculated according to Förster's theory and the value is 3.44 nm. The synchronous and three-dimensional fluorescence spectra show that the binding of Ap to BSA could lead to the changes in the conformation and microenvironment of BSA. At the same time, the effects of ionic surfactants on the interaction of Ap and BSA have also been investigated.

  9. Photometric and spectroscopic study of the intermediate-age open cluster NGC 2355

    NASA Astrophysics Data System (ADS)

    Donati, P.; Bragaglia, A.; Carretta, E.; D'Orazi, V.; Tosi, M.; Cusano, F.; Carini, R.

    2015-11-01

    In this paper we analyse the evolutionary status and properties of the old open cluster NGC 2355, located in the Galactic anticentre direction, as a part of the long-term programme Bologna Open Clusters Chemical Evolution. NGC 2355 was observed with the Large Binocular Camera at the Large Binocular Telescope using the Bessel B, V, and Ic filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram method, as done in other papers of this series. Additional spectroscopic observations with the Fibre-fed Echelle Spectrograph at the Nordic Optical Telescope of three giant stars were used to determine the chemical properties of the cluster. Our analysis shows that NGC 2355 has metallicity slightly less than solar, with [Fe/H]= -0.06 dex, age between 0.8 and 1 Gyr, reddening E(B - V) in the range 0.14-0.19 mag, and distance modulus (m - M)0 of about 11 mag. We also investigate the abundances of O, Na, Al, α, iron-peak, and neutron capture elements, showing that NGC 2355 falls within the abundance distribution of similar clusters (same age and metallicity). The Galactocentric distance of NGC 2355 places it at the border between two regimes of metallicity distribution; this makes it an important cluster for the study of the chemical properties and evolution of the disc.

  10. Spectroscopic studies on the oxidation of carbonyl compounds by OH radicals in the aqueous solution

    NASA Astrophysics Data System (ADS)

    Schaefer, T.; Herrmann, H.

    2009-04-01

    The atmospheric conversation and degradation of volatile organic compounds (VOCs) is often initiated by radical reactions. One of the most important radical in the atmosphere is the OH-radical. Oxidation reactions of water soluble organic compounds in the atmospheric aqueous phase (cloud droplets, fog, rain, deliquescent particles) can be as fast as in the gas phase, but lead to different reaction products or different product distributions. The objective of this work is to identify and characterize the various transient species formed in the oxidation of carbonyl compounds such as acetone. This characterization is necessary to measure rate constants of elementary reaction steps in the course of the degradation process. The spectroscopic and kinetic information obtained will allow a better understanding of the atmospheric fate of carbonyl compounds. In order to characterize the optical properties of the formed transient compounds (e.g. organic peroxy radicals) a laser photolysis long path absorption apparatus coupled with a CCD-camera / grating combination is used. With this technique time resolved spectra (at different delay times after the excimer laser pulse) of the reactants and products can be recorded. Within this contribution organic peroxy radical spectra of the following parent carbonyl compounds (a) acetone, (b) hydroxyacetone, (c) methylglyoxal and (d) pyruvic acid will be presented, discussed and compared with literature data. OH radicals were generated directly in the reaction cell by the photolysis of hydrogen peroxide (H2O2) at 248 nm. All reactions were studied at T = 298K in the aqueous solution.

  11. Spectroscopic studies on the interaction of cinnamic acid and its hydroxyl derivatives with human serum albumin

    NASA Astrophysics Data System (ADS)

    Min, Jiang; Meng-Xia, Xie; Dong, Zheng; Yuan, Liu; Xiao-Yu, Li; Xing, Chen

    2004-04-01

    Cinnamic acid and its derivatives possess various biological effects in remedy of many diseases. Interaction of cinnamic acid and its hydroxyl derivatives, p-coumaric acid and caffeic acid, with human serum albumin (HSA), and concomitant changes in its conformation were studied using fluorescence and Fourier transform infrared spectroscopic methods. Fluorescence data revealed the presence of one binding site on HSA for cinnamic acid and its hydroxyl derivatives, and their binding constants ( KA) are caffeic acid> p-coumaric acid> cinnamic acid when Cdrug/ CHSA ranging from 1 to 10. The changes of the secondary structure of HSA after interacting with the three drugs are estimated, respectively by combining the curve-fitting results of amid I and amid III bands. The α-helix structure has a decrease of ≈9, 5 and 3% after HSA interacted with caffeic acid, p-coumaric acid and cinnamic acid, respectively. It was found that the hydroxyls substituted on aromatic ring of the drugs play an important role in the changes of protein's secondary structure. Combining the result of fluorescence quenching and the changes of secondary structure of HSA after interaction with the three drugs, the drug-HSA interaction mode was discussed.

  12. Spectroscopic investigations, molecular interactions, and molecular docking studies on the potential inhibitor "thiophene-2-carboxylicacid"

    NASA Astrophysics Data System (ADS)

    Karthick, T.; Balachandran, V.; Perumal, S.

    2015-04-01

    Thiophene derivatives have been focused in the past decades due to their remarkable biological and pharmacological activities. In connection with that the conformational stability, spectroscopic characterization, molecular (inter- and intra-) interactions, and molecular docking studies on thiophene-2-carboxylicacid have been performed in this work by experimental FT-IR and theoretical quantum chemical computations. Experimentally recorded FT-IR spectrum in the region 4000-400 cm-1 has been compared with the scaled theoretical spectrum and the spectral peaks have been assigned on the basis of potential energy distribution results obtained from MOLVIB program package. The conformational stability of monomer and dimer conformers has been examined. The presence of inter- and intramolecular interactions in the monomer and dimer conformers have been explained by natural bond orbital analysis. The UV-Vis spectra of the sample in different solvents have been simulated and solvent effects were predicted by polarisable continuum model with TD-DFT/B3LYP/6-31+G(d,p) method. To test the biological activity of the sample, molecular docking (ligand-protein) simulations have been performed using SWISSDOCK web server. The full fitness (FF) score and binding affinity values revealed that thiophene-2-carboxylicacid can act as potential inhibitor against inflammation.

  13. Newly synthesized dihydroquinazoline derivative from the aspect of combined spectroscopic and computational study

    NASA Astrophysics Data System (ADS)

    El-Azab, Adel S.; Mary, Y. Sheena; Mary, Y. Shyma; Panicker, C. Yohannan; Abdel-Aziz, Alaa A.-M.; El-Sherbeny, Magda A.; Armaković, Stevan; Armaković, Sanja J.; Van Alsenoy, Christian

    2017-04-01

    In this work, spectroscopic characterization of 2-(2-(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)ethyl)isoindoline-1,3-dione have been obtained with experimentally and theoretically. Complete assignments of fundamental vibrations were performed on the basis of the potential energy distribution of the vibrational modes and good agreement between the experimental and scaled wavenumbers has been achieved. Frontier molecular orbitals have been used as indicators of stability and reactivity. Intramolecular interactions have been investigated by NBO analysis. The dipole moment, linear polarizability and first and second order hyperpolarizability values were also computed. In order to determine molecule sites prone to electrophilic attacks DFT calculations of average local ionization energy (ALIE) and Fukui functions have been performed as well. Intra-molecular non-covalent interactions have been determined and analyzed by the analysis of charge density. Stability of title molecule have also been investigated from the aspect of autoxidation, by calculations of bond dissociation energies (BDE), and hydrolysis, by calculations of radial distribution functions after molecular dynamics (MD) simulations. In order to assess the biological potential of the title compound a molecular docking study towards breast cancer type 2 complex has been performed.

  14. Mediaeval cantorals in the Valladolid Biblioteca: FT-Raman spectroscopic study.

    PubMed

    Edwards, H G; Farwell, D W; Rull Perez, F; Medina Garcia, J

    2001-03-01

    Raman spectroscopic studies of three mediaeval cantorals in the Biblioteca of the University of Valladolid has revealed information about the pigments used on these large manuscripts. Although executed in a simple colour palette, very pure cinnabar was used as the major colourant, offsetting the carbon black of the verses and script. A dark blue colour was achieved using a mixture of azurite (basic copper carbonate) and carbon, whereas a light blue colour was azurite alone. A grey colour was achieved using azurite, carbon particles and a calcareous 'limewash'. A yellow pigment, used sparely in the cantorals was ascribed to saffron; unusually, there was no evidence for the presence of the yellow mineral pigments orpiment, realgar and massicot. In several regions of the vellum specimens, evidence for biodeterioration was observed through the signatures of hydrated calcium oxalate. We report for the first time the Raman spectra of pigment in situ on a vellum fragment, which also shows evidence of substrate bands; comparison of black and red pigmented regions of vellum specimens has shown the presence of calcium oxalate in the black pigmented script but not in the red pigment regions, which suggests that the cinnabar in the red-pigmented regions acts as a toxic protectant for the vellum substrate against biological colonisation processes.

  15. Spectroscopic, luminescence, electrochemical and antimicrobial studies of lanthanide complexes of bis-benzimidazole derived ligands

    NASA Astrophysics Data System (ADS)

    Siddiqi, Zafar A.; Shahid, Anjuli M.; Khalid, Mohd.; Sharma, Prashant K.; Siddique, Armeen

    2013-04-01

    The lanthanide complexes of [1,2-bis(benzimidazole-2-yl)ethane dihydrochloride], L1·2HCl and [1,4-bis(benzimidazole-2-onium)butane dihydrochloride], L2·2HCl having molecular formulae [Ln(L1)2Cl3H2O] and [Ln(L2)2Cl3H2O]·2H2O (Ln = La3+, Pr3+, Nd3+ and Gd3+), respectively, were prepared and characterized through IR, 1H and 13C NMR, ESI-mass, UV-visible and luminescence spectroscopic techniques. TGA data suggested presence of the coordinated and the lattice water. The oscillator strengths of the f-f transitions and the covalency parameters (β, b1/2 and δ) have been evaluated from the electronic spectral data. The proposed octa coordinate geometry for the complexes has been ascertained from the molecular model computations. CV studies indicate formation of stable quasi-reversible redox couples PrIII/IV, Nd III/IV and GdIII/IV in solution. The in vitro antimicrobial activities of the complexes have been evaluated against gram +ve and gram -ve bacteria and fungi.

  16. Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands.

    PubMed

    Ferraresi-Curotto, Verónica; Echeverría, Gustavo A; Piro, Oscar E; Pis-Diez, Reinaldo; González-Baró, Ana C

    2015-02-25

    Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular O-H⋯N interactions in salicylaldehyde derivatives between the O-H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory.

  17. Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands

    NASA Astrophysics Data System (ADS)

    Ferraresi-Curotto, Verónica; Echeverría, Gustavo A.; Piro, Oscar E.; Pis-Diez, Reinaldo; González-Baró, Ana C.

    2015-02-01

    Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular Osbnd H⋯N interactions in salicylaldehyde derivatives between the Osbnd H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory.

  18. Enzyme inhibition, radical scavenging, and spectroscopic studies of vanadium(IV)-hydrazide complexes.

    PubMed

    Ashiq, Uzma; Jamal, Rifat Ara; Mahroof-Tahir, Mohammad; Maqsood, Zahida T; Khan, Khalid Mohammed; Omer, Iman; Choudhary, Muhammad Iqbal

    2009-12-01

    Spectroscopic, enzyme-inhibition, and free-radical scavenging properties of a series of hydrazide ligands and their vanadium(IV) complexes have been investigated. Analytical and spectral data indicate the presence of a dimeric unit with two oxovanadium(IV) ions (VO(2+)) coordinated with two hydrazide ligands along with two water molecules. All complexes are stable in the solid state, but exhibit varying degrees of stability in solution. Binding of the coordinating solvent such as DMSO is indicated at the 6th position of vanadium in the dimeric unit followed by conversion to a monomeric intermediate species, [VOL(DMSO)3]1+ (L = hydrazide ligand). The free hydrazide ligands are inactive against snake venom phosphodiesterase I (SVPD), whereas oxovanadium(IV) complexes of these ligands show varying degrees of inhibition and are found to be non-competitive inhibitors. The superoxide and nitric oxide radical scavenging properties have been determined. Hydrazide ligands are inactive against these free radicals, whereas their V(IV) complexes show varying degrees of inhibition. Structure-activity relationship studies indicate that the electronic and/or steric factors that change the geometry of the complexes play an important role in their inhibitory potential against SVPD and free radicals.

  19. Studies on the interaction of apigenin with calf thymus DNA by spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Zhang, Shufang; Sun, Xuejun; Kong, Rongmei; Xu, Mingming

    2015-02-01

    The interaction between apigenin and calf thymus deoxyribonucleic acid (ctDNA) in a pH 7.4 Tris-HCl buffer solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy, DNA melting techniques, and viscosity measurements. It was found that apigenin molecules could intercalate into the base pairs of DNA, forming a apigenin-DNA complex with a binding constant of K310K = 6.4 × 104 L mol-1. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) and Gibbs free energy (ΔG) were calculated to be 7.36 × 104 J mol-1, 329 J K-1 mol-1 and -2.84 × 104 J mol-1 at 310 K, respectively. Hydrophobic interaction was the predominant intermolecular force in stabilizing the apigenin-DNA complex. Thermal denaturation study suggested that the stabilization of the ctDNA helix was increased when the apigenin binding to ctDNA as indicated by the increase in thermal denaturation temperature of ctDNA at around 5.0 °C in the presence of apigenin. Spectroscopic techniques together with melting techniques and viscosity determination provided evidences of intercalation mode of binding for the interaction between apigenin and ctDNA.

  20. Spectroscopic and dielectric properties of liquid water: A molecular dynamics simulation study

    NASA Astrophysics Data System (ADS)

    Bursulaya, Badry D.; Kim, Hyung J.

    1998-09-01

    The spectroscopic and dielectric properties of liquid water under an ambient condition are studied via a molecular dynamics (MD) computer simulation method. By employing the recent TAB/10D potential model [B. D. Bursulaya, J. Jeon, D. A. Zichi, and H. J. Kim, J. Chem. Phys. 108, 3286 (1997)], the evolving solvent electronic structure is incorporated into the simulation. Thus both the induced dipole and polarizability variations of individual water molecules with the fluctuating nuclear configuration are accounted for. The MD results on far-IR absorption, depolarized Raman scattering (DRS) and optical Kerr effect (OKE) spectroscopy are in reasonable agreement with experiments. It is found that the nonlinear electronic response of water to its fluctuating environment plays an important role in the DRS and OKE; it significantly enhances the contribution of the water librational motions to the spectra, compared with that of hindered translations. This indicates that not only molecular dynamics but also accompanying electronic structure modulations are essential to quantitative understanding of various electronic spectroscopy. The effects of H/D isotope substitution are briefly discussed.

  1. Spectroscopic studies of carotenoid-to-bacteriochlorophyll energy transfer in LHRC photosynthetic complex from Roseiflexus castenholzii.

    PubMed

    Niedzwiedzki, Dariusz M; Collins, Aaron M; LaFountain, Amy M; Enriquez, Miriam M; Frank, Harry A; Blankenship, Robert E

    2010-07-08

    Carotenoids present in the photosynthetic light-harvesting reaction center (LHRC) complex from chlorosome lacking filamentous anoxygenic phototroph, Roseiflexus castenholzii were purified and characterized for their photochemical properties. The LHRC from anaerobically grown cells contains five different carotenoids, methoxy-keto-myxocoxanthin, gamma-carotene, and its three derivatives, whereas the LHRC from aerobically grown cells contains only three carotenoid pigments with methoxy-keto-myxocoxanthin being the dominant one. The spectroscopic properties and dynamics of excited singlet states of the carotenoids were studied by steady-state absorption, fluorescence and ultrafast time-resolved optical spectroscopy in organic solvent and in the intact LHRC complex. Time-resolved transient absorption spectroscopy performed in the near-infrared (NIR) on purified carotenoids combined with steady-state absorption spectroscopy led to the precise determination of values of the energies of the S(1)(2(1)A(g)(-)) excited state. Global and single wavelength fitting of the ultrafast spectral and temporal data sets of the carotenoids in solvents and in the LHRC revealed the pathways of de-excitation of the carotenoid excited states.

  2. Raman spectroscopic study of Ni/Al 2O 3 catalyst

    NASA Astrophysics Data System (ADS)

    Aminzadeh, A.; Sarikhani-fard, H.

    1999-07-01

    In this article a preliminary Raman spectroscopic study of Ni/Al 2O 3 catalyst of the type used for the steam reformation of methane is reported. With several prepared samples of this catalyst and using FT-Raman and conventional dispersive Raman technique, it is shown how Raman spectroscopy can be used to monitor the exact conditions during the preparation of the catalyst. Raman data shows that despite a strong fluorescence background, some useful information can be obtained. According to these data, when the calcination temperature is raised above 1000°C, the gamma alumina ( γ-Al 2O 3) is converted to alpha alumina ( α-Al 2O 3) as it is expected. It further shows that Ni is not present as NiO: it is probably embedded in the crystal structure of γ-Al 2O 3 as NiAl 2O 4 (the spinel structure) or constituted as a solid solution with Al 2O 3.

  3. Spectroscopic Study of Terahertz Generation in Mid-Infrared Quantum Cascade Lasers

    PubMed Central

    Jiang, Yifan; Vijayraghavan, Karun; Jung, Seungyong; Jiang, Aiting; Kim, Jae Hyun; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus C.; Belkin, Mikhail A.

    2016-01-01

    Terahertz quantum cascade laser sources based on intra-cavity difference-frequency generation are currently the only room-temperature mass-producible diode-laser-like emitters of coherent 1–6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt-level power output and broad tuning from 1.2 to 5.9 THz, all at room-temperature. Terahertz output in these sources originates from intersubband optical nonlinearity in the laser active region. Here we report the first comprehensive spectroscopic study of the optical nonlinearity and investigate its dependence on the mid-infrared pump frequencies. Our work shows that the terahertz generation efficiency can vary by a factor of 2 or greater depending on the spectral position of the mid-infrared pumps for a fixed THz difference-frequency. We have also measured for the first time the linewidth for transitions between the lower quantum cascade laser states, which is critical for determining terahertz nonlinearity and predicting optical loss in quantum cascade laser waveguides. PMID:26879901

  4. Spectroscopic and MD simulation studies on unfolding processes of mitochondrial carbonic anhydrase VA induced by urea.

    PubMed

    Idrees, Danish; Prakash, Amresh; Haque, Md Anzarul; Islam, Asimul; Ahmad, Faizan; Hassan, Md Imtaiyaz

    2016-09-01

    Carbonic anhydrase VA (CAVA) is primarily expressed in the mitochondria and involved in numerous physiological processes including lipogenesis, insulin secretion from pancreatic cells, ureagenesis, gluconeogenesis and neuronal transmission. To understand the biophysical properties of CAVA, we carried out a reversible urea-induced isothermal denaturation at pH 7.0 and 25°C. Spectroscopic probes, [θ]222 (mean residue ellipticity at 222 nm), F344 (Trp-fluorescence emission intensity at 344 nm) and Δε280 (difference absorption at 280 nm) were used to monitor the effect of urea on the structure and stability of CAVA. The urea-induced reversible denaturation curves were used to estimate [Formula: see text], Gibbs free energy in the absence of urea; Cm, the mid-point of the denaturation curve, i.e. molar urea concentration ([urea]) at which ΔGD = 0; and m, the slope (=∂ΔGD/∂[urea]). Coincidence of normalized transition curves of all optical properties suggests that unfolding/refolding of CAVA is a two-state process. We further performed 40 ns molecular dynamics simulation of CAVA to see the dynamics at different urea concentrations. An excellent agreement was observed between in silico and in vitro studies.

  5. Layered structure of room-temperature ionic liquids in microemulsions by multinuclear NMR spectroscopic studies.

    PubMed

    Falcone, R Dario; Baruah, Bharat; Gaidamauskas, Ernestas; Rithner, Christopher D; Correa, N Mariano; Silber, Juana J; Crans, Debbie C; Levinger, Nancy E

    2011-06-06

    Microemulsions form in mixtures of polar, nonpolar, and amphiphilic molecules. Typical microemulsions employ water as the polar phase. However, microemulsions can form with a polar phase other than water, which hold promise to diversify the range of properties, and hence utility, of microemulsions. Here microemulsions formed by using a room-temperature ionic liquid (RTIL) as the polar phase were created and characterized by using multinuclear NMR spectroscopy. (1)H, (11)B, and (19)F NMR spectroscopy was applied to explore differences between microemulsions formed by using 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) as the polar phase with a cationic surfactant, benzylhexadecyldimethylammonium chloride (BHDC), and a nonionic surfactant, Triton X-100 (TX-100). NMR spectroscopy showed distinct differences in the behavior of the RTIL as the charge of the surfactant head group varies in the different microemulsion environments. Minor changes in the chemical shifts were observed for [bmim](+) and [BF(4)](-) in the presence of TX-100 suggesting that the surfactant and the ionic liquid are separated in the microemulsion. The large changes in spectroscopic parameters observed are consistent with microstructure formation with layering of [bmim](+) and [BF(4)](-) and migration of Cl(-) within the BHDC microemulsions. Comparisons with NMR results for related ionic compounds in organic and aqueous environments as well as literature studies assisted the development of a simple organizational model for these microstructures.

  6. Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base

    NASA Astrophysics Data System (ADS)

    Abu Al-Nasr, Ahmad K.; Ramadan, Ramadan M.

    2013-03-01

    Unusual Schiff base ligand, 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl)ethanimidoyl]benzene-1,3-diol, L, was synthesized via catalytic process involving the interaction of some metal ions with a macrocyclic Schiff base (MSB). The transition metal derivatives [ML(H2O)4](NO3)3, M = Cr(III) and Fe(III), [NiL(H2O)4](NO3)2, [ML(H2O)2](NO3)2, M = Zn(II) and Cd(II), [Cl2Pd(μ-Cl)2PdL], [PtL(Cl)2] and [PtL(Cl)4] were also synthesized from the corresponding metal species with L. The Schiff bases and complexes were characterized by elemental analysis, mass spectrometry, IR and 1H NMR spectroscopy. The crystal structure of L was determined by X-ray analysis. The spectroscopic studies revealed a variety of structure arrangements for the complexes. The biological activities of L and metal complexes against the Escherchia coli as Gram-negative bacteria and Staphylococcus aureus as Gram-positive bacteria, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of [PtL(Cl)2] complex, a cis-platin analogous, was checked as an antitumor agent on two breast cancer cell lines (MCF7 and T47D) and human liver carcinoma cell line (HepG2).

  7. A spectroscopic study of the globular cluster M28 (NGC 6626)

    NASA Astrophysics Data System (ADS)

    Villanova, S.; Moni Bidin, C.; Mauro, F.; Munoz, C.; Monaco, L.

    2017-01-01

    We present the abundance analysis for a sample of 17 red giant branch stars in the metal-poor globular cluster M28 based on high-resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, La, Ce, and Eu. We find a metallicity of [Fe/H] = -1.29 ± 0.01 and an α-enhancement of +0.34 ± 0.01 (errors on the mean), typical of halo globular clusters in this metallicity regime. A large spread is observed in the abundances of light elements O, Na, and Al. Mg also shows an anti-correlation with Al with a significance of 3σ. The cluster shows a Na-O anti-correlation and a Na-Al correlation. This correlation is not linear but `segmented' and that the stars are not distributed continuously, but form at least three well-separated sub-populations. In this aspect, M28 resembles NGC 2808 that was found to host at least five sub-populations. The presence of a Mg-Al anti-correlation favour massive AGB stars as the main polluters responsible for the multiple-population phenomenon.

  8. Spectroscopic Studies of Carotenoid-to-Bacteriochlorophyll Energy Transfer in LHRC Photosynthetic Complex from Roseiflexus castenholzii

    SciTech Connect

    Niedzwiedzki, Dariusz; Collins, Aaron M.; LaFountain, Amy M.; Enriquez, Miriam M.; Frank, Harry A.; Blankenship, R. E.

    2010-06-14

    Carotenoids present in the photosynthetic light-harvesting reaction center (LHRC) complex from chlorosome lacking filamentous anoxygenic phototroph, Roseiflexus castenholzii were purified and characterized for their photochemical properties. The LHRC from anaerobically grown cells contains five different carotenoids, methoxy-keto-myxocoxanthin, γ-carotene, and its three derivatives, whereas the LHRC from aerobically grown cells contains only three carotenoid pigments with methoxy-keto-myxocoxanthin being the dominant one. The spectroscopic properties and dynamics of excited singlet states of the carotenoids were studied by steady-state absorption, fluorescence and ultrafast time-resolved optical spectroscopy in organic solvent and in the intact LHRC complex. Time-resolved transient absorption spectroscopy performed in the near-infrared (NIR) on purified carotenoids combined with steady-state absorption spectroscopy led to the precise determination of values of the energies of the S1(21Ag-) excited state. Global and single wavelength fitting of the ultrafast spectral and temporal data sets of the carotenoids in solvents and in the LHRC revealed the pathways of de-excitation of the carotenoid excited states.

  9. Spectroscopic characterization, antimicrobial activity, DFT computation and docking studies of sulfonamide Schiff bases

    NASA Astrophysics Data System (ADS)

    Mondal, Sudipa; Mandal, Santi M.; Mondal, Tapan Kumar; Sinha, Chittaranjan

    2017-01-01

    Schiff bases synthesised from the condensation of 2-(hydroxy)naphthaldehyde and sulfonamides (sufathiazole (STZ), sulfapyridine (SPY), sulfadiazine (SDZ), sulfamerazine (SMZ) and sulfaguanidine (SGN)) are characterized by different spectroscopic data (FTIR, UV-Vis, Mass, NMR) and two of them, (E)-4-(((2-hydroxynaphthalen-1-yl)methylene)amino)-N-(thiazol-2-yl)benzenesulfonamide (1a) and (E)-N-(diaminomethylene)-4-(((2-hydroxynaphthalen-1-yl)methylene)amino)benzenesulfonamide (1e) have been confirmed by single crystal X-ray structure determination. Antimicrobial activities of the Schiff bases have been evaluated against certified and resistant Gram positive (Staphylococcus aureus, Enterococcus facelis) and Gram negative (Streptococcus pyogenes, Salmonella typhi, Shigella dysenteriae, Shigella flexneri, Klebsiella pneumonia) pathogens. Performance of Schiff base against the resistant pathogens are better than standard stain and MIC data lie 32-128 μg/ml while parent sulfonamides are effectively inactive (MIC >512 μg/ml). The DFT optimized structures of the Schiff bases have been used to accomplish molecular docking studies with DHPS (dihydropteroate synthase) protein structure (downloaded from Protein Data Bank) to establish the most preferred mode of interaction. ADMET filtration, Cytotoxicity (MTT assay) and haemolysis assay have been examined for evaluation of druglike character.

  10. {sup 1}H NMR spectroscopic studies establish that heparanase is a retaining glycosidase

    SciTech Connect

    Wilson, Jennifer C.; Laloo, Andrew Elohim; Singh, Sanjesh; Ferro, Vito

    2014-01-03

    Highlights: •{sup 1}H and {sup 13}C NMR chemical shifts of fondaparinux were fully assigned by 1D and 2D NMR techniques. •Hydrolysis of fondaparinux by heparanase was monitored by {sup 1}H NMR spectroscopy. •Heparanase is established to be a retaining glycosidase. -- Abstract: Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains of proteoglycans in basement membranes and the extracellular matrix (ECM). Heparanase is implicated in several diverse pathological processes associated with ECM degradation such as metastasis, inflammation and angiogenesis and is thus an important target for anti-cancer and anti-inflammatory drug discovery. Heparanase has been classed as belonging to the clan A glycoside hydrolase family 79 based on sequence analysis, secondary structure predictions and mutagenic analysis, and thus it has been inferred that it is a retaining glycosidase. However, there has been no direct experimental evidence to support this conclusion. Herein we describe {sup 1}H NMR spectroscopic studies of the hydrolysis of the pentasaccharide substrate fondaparinux by heparanase, and provide conclusive evidence that heparanase hydrolyses its substrate with retention of configuration and is thus established as a retaining glycosidase. Knowledge of the mechanism of hydrolysis may have implications for future design of inhibitors for this important drug target.

  11. Studies of interaction of emodin and DNA in the presence of ethidium bromide by spectroscopic method.

    PubMed

    Bi, Shuyun; Zhang, Hanqi; Qiao, Chunyu; Sun, Ying; Liu, Chunming

    2008-01-01

    Emodin interacting with deoxyribonucleic acid (DNA) has been studied by different spectroscopic techniques, such as fluorescence, ultraviolet and visible (UV-vis), and fourier transform infared (FT-IR) spectroscopies, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of emodin shows that the fluorescence quenching of DNA-EB complex by emodin occurs. The binding constants of emodin with DNA in the presence of EB are 6.02x10(4), 9.20x10(4) and 1.17x10(5)Lmol(-1) at 20, 35 and 50 degrees C, respectively. FT-IR spectrum further suggests that both the phosphate groups and the bases of DNA react with emodin. The reaction of DNA with emodin in the presence of EB is affected by ionic strength and temperature. The values of melting temperature (T(m)) of DNA-EB complex and emodin-DNA-EB complexes were determined, respectively. From the experiment evidences, the major binding mode of emodin with DNA should be the groove binding.

  12. Spectroscopic Studies of Cyclopentane under Extreme Conditions and Implications for the P-T Phase Diagram

    NASA Astrophysics Data System (ADS)

    Ma, Chunli; Liu, Zhenxian; Cui, Qiliang; Hemley, Russell

    2013-06-01

    Infrared (IR) spectroscopy and Raman scattering combined with diamond anvil cell (DAC) and cryogenic techniques have been employed to investigate cyclopentane up to 4 GPa in the temperature range of 100-350 K and isothermal compression up to 84 GPa at room temperature. Four phases including liquid, plastic phases I and II, and truly crystalline phase III are clearly identified in the P-T range studied based on the changes of the ring breathing mode and CH2 rocking modes. The phase diagram is extended to the pressure and temperature range of 0 - 4.0 GPa and 105 - 350 K. Further compression at room temperature up to 84 GPa, another high-pressure phase (IV) is observed based on the appearance of low frequency peaks related to the lattice vibrational modes in the synchrotron far-IR spectra. The spectroscopic results indicate that cyclopentane persists the orientation ordered crystalline phase up to 84 GPa at room temperature. This work was supported by NSF (DMR-0805056; EAR 06-49658, COMPRES) and DOE/ NNSA (DE-FC03-03N00144, CDAC). NSLS is supported by the DOE/BES (DE-AC02-98CH10886).

  13. A spectroscopic study of uranyl-cytochrome b5/cytochrome c interactions

    NASA Astrophysics Data System (ADS)

    Sun, Mei-Hui; Liu, Shuang-Quan; Du, Ke-Jie; Nie, Chang-Ming; Lin, Ying-Wu

    2014-01-01

    Uranium is harmful to human health due to its radiation damage and the ability of uranyl ion (UO22+) to interact with various proteins and disturb their biological functions. Cytochrome b5 (cyt b5) is a highly negatively charged heme protein and plays a key role in mediating cytochrome c (cyt c) signaling in apoptosis by forming a dynamic cyt b5-cyt c complex. In previous molecular modeling study in combination with UV-Vis studies, we found that UO22+ is capable of binding to cyt b5 at surface residues, Glu37 and Glu43. In this study, we further investigated the structural consequences of cyt b5 and cyt c, as well as cyt b5-cyt c complex, upon uranyl binding, by fluorescence spectroscopic and circular dichroism techniques. Moreover, we proposed a uranyl binding site for cyt c at surface residues, Glu66 and Glu69, by performing a molecular modeling study. It was shown that uranyl binds to cyt b5 (KD = 10 μM), cyt c (KD = 87 μM), and cyt b5-cyt c complex (KD = 30 μM) with a different affinity, which slightly alters the protein conformation and disturbs the interaction of cyt b5-cyt c complex. Additionally, we investigated the functional consequences of uranyl binding to the protein surface, which decreases the inherent peroxidase activity of cyt c. The information of uranyl-cyt b5/cyt c interactions gained in this study likely provides a clue for the mechanism of uranyl toxicity.

  14. A spectroscopic study of uranyl-cytochrome b5/cytochrome c interactions.

    PubMed

    Sun, Mei-Hui; Liu, Shuang-Quan; Du, Ke-Jie; Nie, Chang-Ming; Lin, Ying-Wu

    2014-01-24

    Uranium is harmful to human health due to its radiation damage and the ability of uranyl ion (UO2(2+)) to interact with various proteins and disturb their biological functions. Cytochrome b5 (cyt b5) is a highly negatively charged heme protein and plays a key role in mediating cytochrome c (cyt c) signaling in apoptosis by forming a dynamic cyt b5-cyt c complex. In previous molecular modeling study in combination with UV-Vis studies, we found that UO2(2+) is capable of binding to cyt b5 at surface residues, Glu37 and Glu43. In this study, we further investigated the structural consequences of cyt b5 and cyt c, as well as cyt b5-cyt c complex, upon uranyl binding, by fluorescence spectroscopic and circular dichroism techniques. Moreover, we proposed a uranyl binding site for cyt c at surface residues, Glu66 and Glu69, by performing a molecular modeling study. It was shown that uranyl binds to cyt b5 (KD=10 μM), cyt c (KD=87 μM), and cyt b5-cyt c complex (KD=30 μM) with a different affinity, which slightly alters the protein conformation and disturbs the interaction of cyt b5-cyt c complex. Additionally, we investigated the functional consequences of uranyl binding to the protein surface, which decreases the inherent peroxidase activity of cyt c. The information of uranyl-cyt b5/cyt c interactions gained in this study likely provides a clue for the mechanism of uranyl toxicity.

  15. Chiral lactic hydrazone derivatives as potential bioactive antibacterial agents: Synthesis, spectroscopic, structural and molecular docking studies

    NASA Astrophysics Data System (ADS)

    Noshiranzadeh, Nader; Heidari, Azam; Haghi, Fakhri; Bikas, Rahman; Lis, Tadeusz

    2017-01-01

    A series of novel chiral lactic-hydrazone derivatives were synthesized by condensation of (S)-lactic acid hydrazide with salicylaldehyde derivatives and characterized by elemental analysis and spectroscopic studies (FT-IR, 1H NMR and 13C NMR spectroscopy). The structure of one compound was determined by single crystal X-ray analysis. Antibacterial activity of the synthesized compounds was studied against Staphylococcus aureus, Streptococcus pneumonia, Escherichia coli and Pseudomonas aeruginosa as bacterial cultures by broth microdilution method. All of the synthesized compounds showed good antibacterial activity with MIC range of 64-512 μg/mL. Compounds (S,E)-2-hydroxy-N-(2-hydroxy-5-nitrobenzylidene)propanehydrazide (5) and (S,E)-2-hydroxy-N-((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)propanehydrazide (7) were the most effective antibacterial derivatives against S. aureus and E. coli respectively with a MIC value of 64 μg/mL. Bacterial biofilm formation assay showed that these compounds significantly inhibited biofilm formation of P. aeruginosa. Also, in silico molecular docking studies were performed to show lipoteichoic acid synthase (LtaS) inhibitory effect of lactic hydrazone derivatives. The association between electronic and structural effects of some substituents on the benzylidene moiety and the biological activity of these chiral compounds were studied. Structural studies show that compound with higher hydrogen bonding interactions show higher antibacterial activity. The results show chiral hydrazone derivatives based on lactic acid hydrazide could be used as potential lead compounds for developing novel antibacterial agents.

  16. Field-structured composite studies.

    SciTech Connect

    Martin, James Ellis; Williamson, Rodney L.

    2004-04-01

    Field-structured composites (FSCs) were produced by hosting micron-sized gold-coated nickel particles in a pre-polymer and allowing the mixture to cure in a magnetic field environment. The feasibility of controlling a composite's electrical conductivity using feedback control applied to the field coils was investigated. It was discovered that conductivity in FSCs is primarily determined by stresses in the polymer host matrix due to cure shrinkage. Thus, in cases where the structuring field was uniform and unidirectional so as to produce chainlike structures in the composite, no electrical conductivity was measured until well after the structuring field was turned off at the gel point. In situations where complex, rotating fields were used to generate complex, three-dimensional structures in a composite, very small, but measurable, conductivity was observed prior to the gel point. Responsive, sensitive prototype chemical sensors were developed based on this technology with initial tests showing very promising results.

  17. On the motion control of microparticles by means of an electromagnetic field increasing with time for spectroscopic applications

    NASA Astrophysics Data System (ADS)

    Izmailov, A. Ch.

    2017-02-01

    The possibility of controlling the motion of microparticles by means of external electromagnetic fields (nonresonance laser radiation, in particular) that induce potential wells for such particles, which are characterized by fixed spatial distribution but deepen over time to a certain level, are analyzed. It is assumed that the particles are located in high vacuum and are affected by nondissipative external forces. Slowing down of relatively fast particles when they pass through the discussed potential wells is shown. Such slowing down of particles is demonstrated using a nonresonance laser beam with intensity increasing over time as an example. Specific features of particle dynamics in the electromagnetic fields under consideration in the case of a one-dimensional rectangular potential well are studied in detail based on simple analytical relations derived from the fundamental equations of classical mechanics. The methods of particle cooling and localization demonstrated in the present work can substantially increase spectroscopy resolution of various microparticles, including, under certain conditions, atoms and molecules.

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

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1989-01-01

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

  19. Spectroscopic studies of the interaction mechanisms between mono-caffeoylquinic acids and transferrin.

    PubMed

    Guan, Yanqing; Dong, Jing; Chen, Shizhong; Liu, Meixian; Wang, Daidong; Zhang, Xiaotian; Wang, Hong; Lin, Zongtao

    2017-03-07

    Transferrin (Tf) is an important protein responsible for circulating and transporting iron into cytoplasm. Tf can be taken into cells through endocytosis mediated by Tf receptor, which usually overexpresses in cancer cells. The Tf-Tf receptor pathway opens a possible avenue for novel targeted cancer therapy by utilizing Tf-binding active compounds. Among which, anti-cancer active caffeoylquinic acids (CQAs) were recently found to be promising Tf-binders by our group. For better understanding the anti-cancer activities of CQAs, it is important to unveil the binding mechanisms between CQAs and Tf. In this study, the fluorescence quenching, surface plasmon resonance (SPR), circular dichroism (CD) and molecular docking were used to investigate the interactions between CQA and Tf. The results showed that the calculated apparent association constants of interactions between 1-, 3-, 4- and 5-CQA and Tf at 298K were 7.97×10(5)M(-1), 4.36×10(7)M(-1), 6.58×10(5)M(-1) and 4.42×10(6)M(-1), respectively. The thermodynamic parameters indicated that the interaction between 1-, 3-, 5-CQA and Tf is due to H-bonding, and electrostatic interactions were likely involved in the binding of 4-CQA and Tf. The CD results indicated that bindings of 1-CQA, 4-CQA and 5-CQA with Tf resulted in more stretched β-turn and random coil translated from β-sheet. In contrast, 3-CQA led to more stable a-helix conformation. Molecular docking studies of CQAs with Tf further displayed that CQAs were able to interact with residues near Fe(3+) binding site. The spectroscopic studies revealed the action mechanisms, thermodynamics and interacting forces between CQAs and Tf, and thus are helpful for future design and discovery of Tf-binders for targeted cancer therapy applying Tf-Tf receptor pathway.

  20. Line narrowing spectroscopic studies of DNA-carcinogen adducts and DNA-dye complexes

    SciTech Connect

    Suh, Myungkoo

    1995-12-06

    Laser-induced fluorescence line narrowing and non-line narrowing spectroscopic methods were applied to conformational studies of stable DNA adducts of the 7β, 8α-dihydoxy-9α, l0α-epoxy-7,8,9, 10-tetrahydrobenzo[α]pyrene (anti-BPDE). Stereochemically distinct (+)-trans-, (-)-trans-, (+)-cis- and (-)-cis adducts of anti-BPDE bound to exocyclic amino group of the central guanine in an 11-mer oligonucleotide, exist in a mixture of conformations in frozen aqueous buffer matrices. The (+)-trans adduct adopts primarily an external conformation with a smaller fraction ( ~25 %) exists in a partially base-stacked conformation. Both cis adducts were found to be intercalated with significant π-π stacking interactions between the pyrenyl residues and the bases. Conformations of the trans-adduct of (+)-anti -BPDE in 11-mer oligonucleotides were studied as a function of flanking bases. In single stranded form the adduct at G2 or G3 (5 ft-flanking, base guanine) adopts a conformation with strong, interaction with the bases. In contrast, the adduct with a 5ft-flanking, thymine exists in a primarily helixexternal conformation. Similar differences were observed in the double stranded oligonucleotides. The nature of the 3ft-flanking base has little influence on the conformational equilibrium of the (+)-trans-anti BPDE-dG adduct. The formation and repair of BPDE-N2-dG in DNA isolated from the skin of mice treated topically with benzo[α]pyrene (BP) was studied. Low-temperature fluorescence spectroscopy of the intact DNA identified the major adduct as (+)-trans-anti-BPDE-N-dG, and the minor adduct fraction consisted mainly of (+)-cis-anti-BPDE-N2-dG.

  1. Synthesis, X-ray crystallographic, spectroscopic and computational studies of aminothiazole derivatives

    NASA Astrophysics Data System (ADS)

    Adeel, Muhammad; Braga, Ataualpa A. C.; Tahir, Muhammad Nawaz; Haq, Fazal; Khalid, Muhammad; Halim, Mohammad A.

    2017-03-01

    Aminothiazole organic compounds have diverse biological applications. Herein we report the synthesis of two aminothiazole derivatives: 4-(biphenyl-4-yl)thiazol-2-amine (1) and 4-(2‧,4‧-difluorobiphenyl-4-yl)thiazol-2-amine (2) via Suzuki-Miyaura cross coupling reaction. The chemical structures of 1 and 2 are confirmed using 1HNMR, 13CNMR, FT-IR, UV-Vis and single crystal x-ray studies. The XRD study reveals that the both solid state structures (1) and (2) are diffused to form poly chain structures due to presence of intra molecular hydrogen bonding (H.B). Furthermore, these compounds were analysed by density functional theory (DFT) at M06-2X/6-311G(d,p), B3LYP/6-31G(d) B3LYP/6-31G(d,p) and B3LYP/6-311G(2d,p) level of theories to obtain optimized geometry, electronic and spectroscopic properties. DFT optimized geometry supports the experimental XRD parameters. Natural bond orbital (NBO) calculation predicted the hyper conjugative interaction and hydrogen bonding in all derivatives. The FT-IR and thermodynamic studies also confirm the presence of hydrogen bonding network in the dimers which agrees well with the XRD results. Moreover, UV-Vis analysis reveals that maximum excitations take place in 1 and 2 due to HOMO → LUMO(98%) and HOMO → LUMO(97%) respectively which show good agreement to experimental data. The first order hyperpolarizability of both molecules is remarkably greater than the value of urea. The global reactivity parameters which are obtained by frontier molecular orbitals disclose that the molecules might be bioactive.

  2. Near-field single molecule spectroscopy

    SciTech Connect

    Xie, X.S.; Dunn, R.C.

    1995-02-01

    The high spatial resolution and sensitivity of near-field fluorescence microscopy allows one to study spectroscopic and dynamical properties of individual molecules at room temperature. Time-resolved experiments which probe the dynamical behavior of single molecules are discussed. Ground rules for applying near-field spectroscopy and the effect of the aluminum coated near-field probe on spectroscopic measurements are presented.

  3. Case study: in vivo stress diagnostics by spectroscopic determination of the cutaneous carotenoid antioxidant concentration in midwives depending on shift work

    NASA Astrophysics Data System (ADS)

    Maeter, H.; Briese, V.; Gerber, B.; Darvin, M. E.; Lademann, J.; Olbertz, D. M.

    2013-10-01

    Laser spectroscopic methods, for instance resonance Raman spectroscopy and reflectance spectroscopy, permit us for the first time to investigate the antioxidative status in human skin non-invasively by measurement of carotenoid concentration. The individual antioxidant concentration of the human skin is determined by the nutritional habits, on the one hand, and by stressors, such as shift work, on the other. Due to the disturbance of the circadian rhythm and melatonin secretion, shift work is associated with, inter alia, insomnia and gastrointestinal disorders. The study at hand was the first to determine the cutaneous antioxidant concentration of midwives using reflectance spectroscopy and to relate the results to shift work. Seven midwives took part in the study. An LED-based compact scanner system was used for non-invasive measurements of carotenoids in human skin. The measuring principle is based on reflection spectroscopy. The study at hand suggests that the cutaneous antioxidative status may be adversely affected by shift work. Despite numerous international strategies of programmes available which invite people to eat more healthily, there are only a few measures aiming at stress reduction and management. In this field the use of reflectance spectroscopic investigation methods could play an essential role in the future.

  4. Synthesis, Spectroscopic, Structural and Quantum Chemical Studies of a New Imine Oxime and Its Palladium(II) Complex: Hydrolysis Mechanism.

    PubMed

    Kaya, Yunus; Yilmaz, Veysel T; Buyukgungor, Orhan

    2016-01-21

    In this work, we report synthesis, crystallographic, spectroscopic and quantum chemical studies of a new imine oxime, namely (4-nitro-phenyl)-(1-phenyl-ethylimino)-acetaldehyde oxime (nppeieoH). Spectroscopic and X-ray diffraction studies showed that nppeieoH is hydrolyzed in aqueous solution, forming nitroisonitrosoacetophenone (ninap) and the hydrolysis product binds to Pd(II) to yield [Pd(nppeieo)(ninap)]. The mechanism of the hydrolysis reaction has been theoretically investigated in detail, using density functional theory (DFT) with the B3LYP method. The vibrational and the electronic spectra of nppeieoH and its Pd(II) complex, the HOMO and LUMO analysis, Mulliken atomic charges and molecular electrostatic potential were also performed. The predicted nonlinear optical properties of both compounds are higher than those of urea.

  5. In situ spectroscopic studies on vapor phase catalytic decomposition of dimethyl oxalate.

    PubMed

    Hegde, Shweta; Tharpa, Kalsang; Akuri, Satyanarayana Reddy; K, Rakesh; Kumar, Ajay; Deshpande, Raj; Nair, Sreejit A

    2017-03-15

    Dimethyl Oxalate (DMO) has recently gained prominence as a valuable intermediate for the production of compounds of commercial importance. The stability of DMO is poor and hence this can result in the decomposition of DMO under reaction conditions. The mechanism of DMO decomposition is however not reported and more so on catalytic surfaces. Insights into the mechanism of decomposition would help in designing catalysts for its effective molecular transformation. It is well known that DMO is sensitive to moisture, which can also be a factor contributing to its decomposition. The present work reports the results of decomposition of DMO on various catalytic materials. The materials studied consist of acidic (γ-Al2O3), basic (MgO), weakly acidic (ZnAl2O4) and neutral surfaces such as α-Al2O3 and mesoporous precipitated SiO2. Infrared spectroscopy is used to identify the nature of adsorption of the molecule on the various surfaces. The spectroscopy study is done at a temperature of 200 °C, which is the onset of gas phase decomposition of DMO. The results indicate that the stability of DMO is lower than the corresponding acid, i.e. oxalic acid. It is also one of the products of decomposition. Spectroscopic data suggest that DMO decomposition is related to surface acidity and the extent of decomposition depends on the number of surface hydroxyl groups. Decomposition was also observed on α-Al2O3, which was attributed to the residual surface hydroxyl groups. DMO decomposition to oxalic acid was not observed on the basic surface (MgO).

  6. Spectroscopic Study of Methylglyoxal and its Hydrates : a Gaseous Precursor of Secondary Organic Aerosols.

    NASA Astrophysics Data System (ADS)

    Bteich, Sabath; Goubet, Manuel; Margulès, L.; Motiyenko, R. A.; Huet, T. R.

    2016-06-01

    Secondary organic aerosols (SOA) have a significant effect on climate change. They are mainly produced in the atmosphere by oxidation of gaseous precursors. Fu et al. have suggested trans-methylglyoxal (MG) as a possible precursor of SOA in the cloud for its presence in large quantities in the atmosphere. The characterization of SOAs precursors by laboratory spectroscopy allows providing elements for the understanding of the process of formation of these aerosols. For this purpose, we completed the existing pure rotational spectrum of MG in the 12-40 GHz range by new records in a supersonic jet in the 4-20 GHz range (FTMW) and at room temperature in the 150-500 GHz range (mm/submm-wave spectrometer). The analysis was made with the support of quantum chemistry calculations (MP2/CBS and B98/CBS using the Gaussian 09 software). The adjustment of the spectroscopic parameters, taking into account the internal rotation related to the presence of a methyl group, was performed using the RAM36 code. The spectra have been reproduced at the experimental precision up to maximal values of J and K_a equal to 85 and 35, respectively. The data obtained for the isolated molecule, both experimentally and theoretically, will allow the study of its hydrated complexes and, by comparison, will give access to (micro-) hydration properties. For this purpose, two stable complexes predicted by theoretical calculations will be studied. T.- M. Fu et al., J. Geophys. Res., 113, (2008). C.E. Dyltick-Brenzinger and A. Bauder, Chem. Phys. 30, 147 (1978).

  7. Equilibrium, Kinetics, and Spectroscopic Studies of SF6 Hydrate in NaCl Electrolyte Solution.

    PubMed

    Seo, Youngrok; Moon, Donghyun; Lee, Changho; Park, Jeong-Woo; Kim, Byeong-Soo; Lee, Gang-Woo; Dotel, Pratik; Lee, Jong-Won; Cha, Minjun; Yoon, Ji-Ho

    2015-05-19

    Many studies have focused on desalination via hydrate formation; however, for their potential application, knowledge pertaining to thermodynamic stability, formation kinetics, and guest occupation behavior in clathrate hydrates needs to be determined. Herein, the phase equilibria of SF6 hydrates in the presence of NaCl solutions (0, 2, 4, and 10 wt %) were monitored in the temperature range of 277-286 K and under pressures of up to 1.4 MPa. The formation kinetics of SF6 hydrates in the presence of NaCl solutions (0, 2, and 4 wt %) was also investigated. Gas consumption curves of SF6 hydrates showed that a pure SF6 hydrate system allowed fast hydrate growth as well as high conversion yield, whereas SF6 hydrate in the presence of NaCl solutions showed retarded hydrate growth rate as well as low conversion yield. In addition, structural identification of SF6 hydrates with and without NaCl solutions was performed using spectroscopic tools such as Raman spectroscopy and X-ray diffraction. The Raman spectrometer was also used to evaluate the temperature-dependent release behavior of guest molecules in SF6 and SF6 + 4 wt % NaCl hydrates. The results indicate that whereas SF6 hydrate starts to decompose at around 240 K, the escape of SF6 molecules in SF6 + 4 wt % NaCl hydrate is initiated rapidly at around 205 K. The results of this study can provide a better understanding of guest-host interaction in electrolyte-containing systems.

  8. EMISSION-LINE GALAXIES FROM THE HUBBLE SPACE TELESCOPE PROBING EVOLUTION AND REIONIZATION SPECTROSCOPICALLY (PEARS) GRISM SURVEY. I. THE SOUTH FIELDS

    SciTech Connect

    Straughn, Amber N.; Gardner, Jonathan P.; Pirzkal, Norbert; Grogin, Norman; Panagia, Nino; Meurer, Gerhardt R.; Cohen, Seth H.; Windhorst, Rogier A.; Malhotra, Sangeeta; Rhoads, James; Jansen, Rolf A.; Hathi, Nimish P.; Di Serego Alighieri, Sperello; Gronwall, Caryl; Walsh, Jeremy; Pasquali, Anna; Xu, Chun

    2009-10-15

    We present results of a search for emission-line galaxies (ELGs) in the southern fields of the Hubble Space Telescope Probing Evolution And Reionization Spectroscopically (PEARS) grism survey. The PEARS South Fields consist of five Advanced Camera for Surveys pointings (including the Hubble Ultra Deep Field) with the G800L grism for a total of 120 orbits, revealing thousands of faint object spectra in the GOODS-South region of the sky. ELGs are one subset of objects that are prevalent among the grism spectra. Using a two-dimensional detection and extraction procedure, we find 320 emission lines originating from 226 galaxy 'knots' within 192 individual galaxies. Line identification results in 118 new grism-spectroscopic redshifts for galaxies in the GOODS-South Field. We measure emission-line fluxes using standard Gaussian fitting techniques. At the resolution of the grism data, the H{beta} and [O III] doublet are blended. However, by fitting two Gaussian components to the H{beta} and [O III] features, we find that many of the PEARS ELGs have high [O III]/H{beta} ratios compared to other galaxy samples of comparable luminosities. The star formation rates of the ELGs are presented, as well as a sample of distinct giant star-forming regions at z {approx} 0.1-0.5 across individual galaxies. We find that the radial distances of these H II regions in general reside near the galaxies' optical continuum half-light radii, similar to those of giant H II regions in local galaxies.

  9. Spectroscopic and quantum chemical study of the structure of a new paramagnetic dimeric palladium(II,III) complex with creatine

    NASA Astrophysics Data System (ADS)

    Mitewa, Mariana; Enchev, Venelin; Bakalova, Tatyana

    2002-05-01

    The structure and coordination mode of the newly synthesized dimeric paramagnetic Pd(II,III) complex are studied using magneto-chemical, EPR and IR spectroscopic methods. In order to perform reliable assignment of the IR bands, the structure and IR spectrum of the free creatine were calculated using ab initio method. For calculation of the configuration of its deprotonated and doubly deprotonated forms the semiempirical AM1 method was used.

  10. Finite-temperature behavior of lattice QCD with Wilson fermion action and its implication on spectroscopic studies

    SciTech Connect

    Fukugita, M.; Ohta, S.; Ukawa, A.

    1986-10-20

    Finite-temperature behavior of lattice QCD is studied with the Wilson fermion action and use of the Langevin technique for treating quarks dynamically. It is found that the transition zone from low- to high-temperature behavior does not cross the line of critical hopping parameter, but rather continues down to the strong-coupling limit. Practical implications for spectroscopic simulations at small quark masses are discussed.

  11. Spectroscopic study of extended star clusters in dwarf galaxy NGC 6822

    SciTech Connect

    Hwang, Narae; Kim, Sang Chul; Park, Hong Soo; Lee, Myung Gyoon; Lim, Sungsoon; Hodge, Paul W.; Weisz, Daniel; Miller, Bryan

    2014-03-01

    We present a spectroscopic study of the four extended star clusters (ESCs) in NGC 6822 based on the data obtained with the Gemini Multi-Object Spectrograph on the Gemini-South 8.1 m telescope. The radial velocities derived from the spectra range from –61.2 ± 20.4 km s{sup –1} (for C1) to –115.34 ± 57.9 km s{sup –1} (for C4) and, unlike the intermediate-age carbon stars, they do not display any sign of systematic rotation around NGC 6822. The ages and metallicities derived using the Lick indices show that the ESCs are old (≥8 Gyr) and metal poor ([Fe/H] ≲ –1.5). NGC 6822 is found to have both metal poor ([Fe/H] ≈–2.0) and metal rich ([Fe/H] ≈–0.9) star clusters within 15' (2 kpc) from the center, whereas only metal poor clusters are observed in the outer halo with r ≥ 20'(2.6 kpc). The kinematics, old ages, and low metallicities of ESCs suggest that ESCs may have accreted into the halo of NGC 6822. Based on the velocity distribution of ESCs, we have determined the total mass and the mass-to-light ratio of NGC 6822: M{sub N6822}=7.5{sub −0.1}{sup +4.5}×10{sup 9} M{sub ⊙} and (M/L){sub N6822}=75{sub −1}{sup +45}(M/L){sub ⊙}. It shows that NGC 6822 is one of the most dark matter dominated dwarf galaxies in the Local Group.

  12. Imaging and spectroscopic performance studies of pixellated CdTe Timepix detector

    NASA Astrophysics Data System (ADS)

    Maneuski, D.; Astromskas, V.; Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Marchal, J.; O'Shea, V.; Stewart, G.; Tartoni, N.; Wilhelm, H.; Wraight, K.; Zain, R. M.

    2012-01-01

    In this work the results on imaging and spectroscopic performances of 14 × 14 × 1 mm CdTe detectors with 55 × 55 μm and 110 × 110 μm pixel pitch bump-bonded to a Timepix chip are presented. The performance of the 110 × 110 μm pixel detector was evaluated at the extreme conditions beam line I15 of the Diamond Light Source. The energy of X-rays was set between 25 and 77 keV. The beam was collimated through the edge slits to 20 μm FWHM incident in the middle of the pixel. The detector was operated in the time-over-threshold mode, allowing direct energy measurement. Energy in the neighbouring pixels was summed for spectra reconstruction. Energy resolution at 77 keV was found to be ΔE/E = 3.9%. Comparative imaging and energy resolution studies were carried out between two pixel size detectors with a fluorescence target X-ray tube and radioactive sources. The 110 × 110 μm pixel detector exhibited systematically better energy resolution in comparison to 55 × 55 μm. An imaging performance of 55 × 55 μm pixellated CdTe detector was assessed using the Modulation Transfer Function (MTF) technique and compared to the larger pixel. A considerable degradation in MTF was observed for bias voltages below -300 V. Significant room for improvement of the detector performance was identified both for imaging and spectroscopy and is discussed.

  13. Spectroscopic study on sorption of hydrogen sulfide by means of red soil

    NASA Astrophysics Data System (ADS)

    Ko, T. H.; Chu, H.

    2005-07-01

    This paper reports the results of the characterization of red soils in relation to the sorption of H 2S from coal gas at 500 °C by spectroscopic techniques in order to provide more information on red soils' structural change both before and after reaction. In addition, by-products analysis has also been studied using Fourier transform infrared (FTIR) spectroscopy. Before and after the experiments the red soils were characterized with X-ray powder diffraction (XRPD), energy dispersion spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and FTIR spectroscopy. XRPD results indicate that iron oxide species disappear from the original to reacted red soil. EDS analysis shows that a significant amount of sulfur is present in the reacted red soil, which is in agreement with the results of the elemental analysis and the calculated value based on breakthrough curve. XPS regression fitting results further indicate that sulfur retention may be associated with the iron oxides. S 2p XPS fittings point out that the major sulfur species present in the reacted red soil are composed of S -2, elemental sulfur, polysulfide, sulfite and sulfate. Additionally, the binding energy of iron shifts to a lower position for the reacted red soil, which indicates that iron oxides in the original red soil have been converted into iron sulfide. Appreciable amounts of the by-products CO 2, SO 2 and COS are detected by on-line FTIR spectroscopy during the initial and later stages of the sorption process. The formation of CO 2 is related to the water-shift reaction, and SO 2 is probably attributable to the reaction of organic matters and H 2S. The concentration of COS is quantified by GC/FPD and found it to be about 350 ppm, which is close to the equilibrium concentration of the reaction of inlet CO and H 2S at a temperature of 500 °C.

  14. Spectroscopic study on sorption of hydrogen sulfide by means of red soil.

    PubMed

    Ko, T H; Chu, H

    2005-07-01

    This paper reports the results of the characterization of red soils in relation to the sorption of H2S from coal gas at 500 degrees C by spectroscopic techniques in order to provide more information on red soils' structural change both before and after reaction. In addition, by-products analysis has also been studied using Fourier transform infrared (FTIR) spectroscopy. Before and after the experiments the red soils were characterized with X-ray powder diffraction (XRPD), energy dispersion spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and FTIR spectroscopy. XRPD results indicate that iron oxide species disappear from the original to reacted red soil. EDS analysis shows that a significant amount of sulfur is present in the reacted red soil, which is in agreement with the results of the elemental analysis and the calculated value based on breakthrough curve. XPS regression fitting results further indicate that sulfur retention may be associated with the iron oxides. S 2p XPS fittings point out that the major sulfur species present in the reacted red soil are composed of S(-2), elemental sulfur, polysulfide, sulfite and sulfate. Additionally, the binding energy of iron shifts to a lower position for the reacted red soil, which indicates that iron oxides in the original red soil have been converted into iron sulfide. Appreciable amounts of the by-products CO2, SO2 and COS are detected by on-line FTIR spectroscopy during the initial and later stages of the sorption process. The formation of CO2 is related to the water-shift reaction, and SO2 is probably attributable to the reaction of organic matters and H2S. The concentration of COS is quantified by GC/FPD and found it to be about 350 ppm, which is close to the equilibrium concentration of the reaction of inlet CO and H2S at a temperature of 500 degrees C.

  15. Photometric and spectroscopic study of the ultra-faint Milky Way satellite Pegasus III

    NASA Astrophysics Data System (ADS)

    Kim, Dongwon; Jerjen, Helmut; Geha, Marla C.; Chiti, Anirudh; Milone, Antonino; Da Costa, Gary S.; Mackey, Dougal; Frebel, Anna; Conn, Blair

    2017-01-01

    Pegasus III (Peg III) is one of the few known ultra-faint dwarf (UFD) satellite galaxies in the outer halo (R >150 kpc) of the Milky Way (MW). We present results from a recent study of Peg III using Magellan/IMACS and Keck/DEIMOS. Our newly-measured structural parameters confirm that Peg III is large (rh = 53±14pc), elongated (∈ = 0.38+0.22-0.38 ), and faint (MV=-3.4±0.4 mag) — indicative of its nature as a dwarf rather than a globular cluster. In the color-magnitude diagram, Peg III is well described by an old (>12Gyr) and metal-poor ([Fe/H]<-2.0 dex) stellar population at a heliocentric distance of 215±12 kpc. Using spectroscopic measurements of individual stars, we identify seven kinematic members of Peg III. The Ca II triplet lines of the brightest members verify that Peg III indeed contains stars with metallicity as low as [Fe/H]=-2.55±0.15 dex. The systemic velocity and velocity dispersion of Peg III are -222.9±2.6 km/s and 5.4+3.0-2.5 km/s, respectively. The inferred dynamical mass within the half-light radius of 1.4+3.0-1.1×106M⊙, and the mass-to-light ratio of M/LV = 1470+5660-1240M⊙/L⊙ provide further evidence that Peg III is a bona fide UFD. Peg III and another distant UFD Pisces II lie relatively close to each other (△dspatial=43±19 kpc) and share similar systemic radial velocities (△vGSR=12.3±3.7 km/s), which suggests that they may share a common origin.

  16. A spectroscopic and photometric study of the planetary nebulae Kn 61 and Pa 5

    SciTech Connect

    García-Díaz, Ma. T.; González-Buitrago, D.; López, J. A.; Zharikov, S.; Tovmassian, G.; Borisov, N.; Valyavin, G. E-mail: dgonzalez@astro.unam.mx E-mail: zhar@astro.unam.mx E-mail: borisov@sao.ru

    2014-09-01

    We present the first morpho-kinematical analysis of the planetary nebulae Kn 61 and Pa 5 and explore the nature of their central stars. Our analysis is based on high-resolution and medium-resolution spectroscopic observations, deep narrow-band imaging, and integral photometry. This material allows us to identify the morphological components and study their kinematics. The direct images and spectra indicate an absence of the characteristic [N II] and [S II] emission lines in both nebulae. The nebular spectrum of Kn 61 suggests a hydrogen deficient planetary nebula and the stellar spectrum of the central star reveals a hydrogen-deficient PG 1159-type star. The [O III] position velocity diagram reveals that Kn 61 is a closed, empty, spherical shell with a thin border and a filamentary surface expanding at 67.6 km s{sup –1} and the shell is currently not expanding isotropically. We derived a kinematic age of ∼1.6 × 10{sup 4} yr for an assumed distance of 4 kpc. A photometric period of ∼5.7(±0.4) days has been detected for Kn 61, indicating the presence of a possible binary system at its core. A possible link between filamentary spherical shells and PG 1159-type stars is noted. The morphology of Pa 5 is dominated by an equatorial toroid and faint polar extensions. The equatorial region of this planetary nebula is expanding at 45.2 km s{sup –1}. The stellar spectrum corresponds to a very hot star and is dominated by a steep blue rising continuum and He II, Balmer, and Ca II photospheric lines.

  17. Solvatochromism of 9,10-phenanthrenequinone: An electronic and resonance Raman spectroscopic study

    SciTech Connect

    Ravi Kumar, Venkatraman; Rajkumar, Nagappan; Umapathy, Siva

    2015-01-14

    Solvent effects play a vital role in various chemical, physical, and biological processes. To gain a fundamental understanding of the solute-solvent interactions and their implications on the energy level re-ordering and structure, UV-VIS absorption, resonance Raman spectroscopic, and density functional theory calculation studies on 9,10-phenanthrenequinone (PQ) in different solvents of diverse solvent polarity has been carried out. The solvatochromic analysis of the absorption spectra of PQ in protic dipolar solvents suggests that the longest (1n-π{sup 1}*; S{sub 1} state) and the shorter (1π-π{sup 1}*; S{sub 2} state) wavelength band undergoes a hypsochromic and bathochromic shift due to intermolecular hydrogen bond weakening and strengthening, respectively. It also indicates that hydrogen bonding plays a major role in the differential solvation of the S{sub 2} state relative to the ground state. Raman excitation profiles of PQ (400–1800 cm{sup −1}) in various solvents followed their corresponding absorption spectra therefore the enhancements on resonant excitation are from single-state rather than mixed states. The hyperchromism of the longer wavelength band is attributed to intensity borrowing from the nearby allowed electronic transition through vibronic coupling. Computational calculation with C{sub 2ν} symmetry constraint on the S{sub 2} state resulted in an imaginary frequency along the low-frequency out-of-plane torsional modes involving the C=O site and therefore, we hypothesize that this mode could be involved in the vibronic coupling.

  18. Spectroscopic and structural study of proton and halide ion cooperative binding to gfp.

    PubMed

    Arosio, Daniele; Garau, Gianpiero; Ricci, Fernanda; Marchetti, Laura; Bizzarri, Ranieri; Nifosì, Riccardo; Beltram, Fabio

    2007-07-01

    This study reports the influence of halogens on fluorescence properties of the Aequorea victoria Green Fluorescent Protein variant S65T/T203Y (E(2)GFP). Halide binding forms a specific nonfluorescent complex generating a substantial drop of the fluorescence via static quenching. Spectroscopic analysis under different solution conditions reveals high halogen affinity, which is strongly dependent on the pH. This evidences the presence in E(2)GFP of interacting binding sites for halide ions and for protons. Thermodynamic link and cooperative interaction are assessed demonstrating that binding of one halide ion is associated with the binding of one proton in a cooperative fashion with the formation, in the pH range 4.5-10, of a single fully protonated E(2)GFP.halogen complex. To resolve the structural determinants of E(2)GFP sensitivity to halogens, high-resolution crystallographic structures were obtained for the halide-free and I(-), Br(-), and Cl(-) bound E(2)GFP. Remarkably the first high-resolution (1.4 A) crystallographic structure of a chloride-bound GFP is reported. The chloride ion occupies a specific and unique binding pocket in direct contact (3.4 A) with the chromophore imidazolidinone aromatic ring. Unanticipated flexibility, strongly modulated by halide ion interactions, is observed in the region surrounding the chromophore. Furthermore molecular dynamics simulations identified E222 residue (along with the chromophore Y66 residue) being in the protonated state when E(2)GFP.halogen complex is formed. The impact of these results on high-sensitivity biosensor design will be discussed.

  19. Thermodynamic and Spectroscopic Studies of Lanthanides(III) Complexation with Polyamines in Dimethyl Sulfoxide

    SciTech Connect

    Di Bernardo, Plinio; Zanonato, Pier Luigi; Melchior, Andrea; Portanova, Roberto; Tolazzi, Marilena; Choppin, Gregory R.; Wang, Zheming

    2008-01-01

    The thermodynamic parameters of complexation of Ln(III) cations with tris(2-aminoethyl)amine (tren) and tetraethylenepentamine (tetren) were determined in dimethyl sulfoxide (DMSO) by potentiometry and calorimetry. The excitation and emission spectra and luminescence decay constants of Eu3+ and Tb3+ complexed by tren and tetren, as well as those of the same lanthanides(III) complexed with diethylenetriamine (dien) and triethylenetetramine (trien), were also obtained in the same solvent. The combination of thermodynamic and spectroscopic data showed that, in the 1:1 complexes, all nitrogens of the ligands bound to the lanthanides except in the case of tren, in which only pendant N bound. For the larger ligands (trien, tren, tetren) in the higher complexes (ML2), there was less complete binding by available donors, presumably due to steric crowding. FT-IR studies were carried out in an acetonitrile/DMSO mixture, suitably chosen in order to follow the changes in the primary solvation sphere of lanthanide(III) due to complexation of amine ligands. Results show that the mean number of molecules of DMSO removed from the inner coordination sphere of lanthanides(III) is lower than ligand denticity and that the coordination number of the metal ions increases with amine complexation from ~8 to ~10. Independently of the number and structure of the amines, linear trends, similar for all lanthanides, were obtained by plotting the values of ΔGj°, ΔHj° and TΔSj° for the complexation of ethylenediamine (en), dien, trien, tren and tetren as a function of the number of amine metal-coordinated nitrogen atoms. The main factors on which the thermodynamic functions of lanthanide(III) complexation reactions in DMSO depend are discussed.

  20. Raman Spectroscopic Study Of The Dehydration Of Sulfates Using An Acoustic Levitator

    NASA Astrophysics Data System (ADS)

    Brotton, Stephen; Kaiser, R.

    2012-10-01

    The martian orbiters, landers, and rovers identified water-bearing sulfates on the martian surface. Furthermore, the Galileo mission suggests that hydrated salts such as magnesium sulfate are present on the surface of Europa and Ganymede. To understand the hydrologic history of Mars and some of Jupiter’s and Saturn’s moons, future missions need to identify in situ the hydration states of sulfates including magnesium sulfate (MgSO4 • nH2O n = 7, 6, . . ., 0), gypsum (CaSO4 • 2H2O), bassanite (CaSO4 • 0.5H2O) and anhydrite (CaSO4). Raman spectroscopy is ideally suited for this purpose, since the Raman spectrum for each different degree of hydration is unique. To obtain laboratory Raman spectra for comparison with the in situ measurements, we have developed a novel apparatus combining an acoustic levitator and a pressure-compatible process chamber. Particles with diameters between 10 µm and a few mm can be levitated at the pressure nodes of the ultrasonic standing wave. The chamber is interfaced to complimentary FTIR and Raman spectroscopic probes to characterize any chemical and physical modifications of the levitated particles. The particles can be heated to well-defined temperatures between 300 K and 1000 K using a carbon dioxide laser; the temperature of the particle will be probed via its black-body spectrum. The present apparatus enables (i) the production of high particle temperatures, (ii) precise measurement of the temperature, and (iii) accurate control of the environmental conditions (gas pressure and composition) within the chamber. Using this apparatus, we have studied the dehydration of sulfates including gypsum and epsomite (MgSO4 • 7H2O) in an anhydrous nitrogen atmosphere. We will present spectra showing the variation of the Raman spectra as gypsum, for example, is dehydrated to form anhydrite.

  1. Binary star orbits from speckle interferometry. 5: A combined speckle/spectroscopic study of the O star binary 15 Monocerotis

    NASA Technical Reports Server (NTRS)

    Gies, Douglas R.; Mason, Brian D.; Hartkopf, William I.; Mcalister, Harold A.; Frazin, Richard A.; Hahula, Michael E.; Penny, Laura R.; Thaller, Michelle L.; Fullerton, Alexander W.; Shara, Michael M.

    1993-01-01

    We report on the discovery of a speckle binary companion to the O7 V (f) star 15 Monocerotis. A study of published radial velocities in conjunction with new measurements from Kitt Peak National Observatory (KPNO) and IUE suggests that the star is also a spectroscopic binary with a period of 25 years and a large eccentricity. Thus, 15 Mon is the first O star to bridge the gap between the spectroscopic and visual separation regimes. We have used the star's membership in the cluster NGC 2264 together with the cluster distance to derive masses of 34 and 19 solar mass for the primary and secondary, respectively. Several of the He I line profiles display a broad shallow component which we associate with the secondary, and we estimate the secondary's classification to be O9.5 Vn. The new orbit leads to several important predictions that can be tested over the next few years.

  2. Spectroscopic study of the light-harvesting protein C-phycocyanin associated with colorless linker peptides

    SciTech Connect

    Pizarro, Shelly Ann

    2000-05-01

    The phycobilisome (PBS) light-harvesting antenna is composed of chromophore-containing biliproteins and 'colorless' linker peptides and is structurally designed to support unidirectional transfer of excitation energy from the periphery of the PBS to its core. The linker peptides have a unique role in this transfer process by modulating the spectral properties of the associated biliprotein. There is only one three-dimensional structure of a biliprotein/linker complex available to date (APC/LC7.8) and the mechanism of interaction between these two proteins remains unknown. This study brings together a detailed spectroscopic characterization of C-Phycocyanin (PC)-linker complexes (isolated from Synechococcus sp. PCC 7002) with proteomic analysis of the linker amino acid sequences to produce a model for biliprotein/linker interaction. The amino acid sequences of the rod linkers [LR8.9, LR32.3 and LRC28.5] were examined to identify evolutionarily conserved regions important to either the structure or function of this protein family. Although there is not one common homologous site among all the linkers, there are strong trends across each separate subset (LC, LR and LRC) and the N-terminal segments of both LR32.3 and LRC28.5 display multiple regions of similarity with other linkers. Predictions of the secondary structure of LR32.3 and LRC28.5, and comparison to the crystal structure of LC7.8, further narrowed the candidates for interaction sites with the PC chromophores. Measurements of the absorption, fluorescence, CD and excitation anisotropy of PC trimer, PC/LR32.3, and PC/LRC28.5, document the spectroscopic effect of each linker peptide on the PC chromophores at a series of temperatures (298 to 77 K). Because L

  3. Synthesis, spectroscopic identification, thermal, potentiometric and antibacterial activity studies of 4-amino-5-mercapto-S-triazole Schiff's base complexes

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Zayed, Mohamed E.; Alharbi, Suliman A.; Ammar, Reda A. A.; Chinnathambi, Arunachalam

    2015-05-01

    Complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) of general composition [M(L)2] have been synthesized [L = 4-pyridin-2-yl-methylene amino-4H-1,2,4-triazole-3-thiol]. The elemental analyses, molar conductance, spectral (IR, UV-Vis, 1H NMR, mass), magnetic moment and thermal measurements studies of the compounds led to the conclusion that the ligand acts as a tridentate manner (SNN). The molar conductance of the metal complexes in fresh solution of DMSO lies in the range of 8.34-10.46 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of analytical and spectroscopic techniques, octahedral geometry of the complexes was proposed. The Schiff base acts as tridentate ligand coordinated through deprotonated thiolic sulfur, azomethine nitrogen and pyridine nitrogen atoms. The ligand field parameters were calculated for Co(II), Ni(II) and Cu(II) complexes and their values were found in the range reported for a octahedral structure. The data show that the complexes have composition of ML2 type. The activation of thermodynamic parameters are calculated using Coast-Redfern, Horowitz-Metzger (HM), Piloyan-Novikova (PN) and Broido's equations. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 °C and ionic strength 0.10 M potassium nitrate. Both the Schiff's base ligand and its complexes have been screened for antibacterial activities.

  4. FIRST SPECTROSCOPIC MEASUREMENTS OF [O III] EMISSION FROM Ly{alpha} SELECTED FIELD GALAXIES AT z {approx} 3.1

    SciTech Connect

    McLinden, Emily M.; Rhoads, James E.; Malhotra, Sangeeta; Hibon, Pascale; Richardson, Mark L. A.; Finkelstein, Steven L.; Cresci, Giovanni; Quirrenbach, Andreas; Pasquali, Anna; Bian Fuyan; Fan Xiaohui; Woodward, Charles E.

    2011-04-01

    We present the first spectroscopic measurements of the [O III] 5007 A line in two z {approx} 3.1 Ly{alpha} emitting galaxies (LAEs) using the new near-infrared instrument LUCIFER1 on the 8.4 m Large Binocular Telescope. We also describe the optical imaging and spectroscopic observations used to identify these LAEs. Using the [O III] line we have measured accurate systemic redshifts for these two galaxies, and discovered a velocity offset between the [O III] and Ly{alpha} lines in both, with the Ly{alpha} line peaking 342 and 125 km s{sup -1} redward of the systemic velocity. These velocity offsets imply that there are powerful outflows in high-redshift LAEs. They also ease the transmission of Ly{alpha} photons through the interstellar medium and intergalactic medium around the galaxies. By measuring these offsets directly, we can refine both Ly{alpha}-based tests for reionization, and Ly{alpha} luminosity function measurements where the Ly{alpha} forest affects the blue wing of the line. Our work also provides the first direct constraints on the strength of the [O III] line in high-redshift LAEs. We find [O III] fluxes of 7 and 36 x10{sup -17} erg s{sup -1} cm{sup -2} in two z {approx} 3.1 LAEs. These lines are strong enough to dominate broadband flux measurements that include the line (in this case, K{sub s} -band photometry). Spectral energy distribution fits that do not account for the lines would therefore overestimate the 4000 A (and/or Balmer) break strength in such galaxies, and hence also the ages and stellar masses of such high-z galaxies.

  5. Structural transformation of synthetic hydroxyapatite under simulated in vivo conditions studied with ATR-FTIR spectroscopic imaging.

    PubMed

    Sroka-Bartnicka, Anna; Borkowski, Leszek; Ginalska, Grazyna; Ślósarczyk, Anna; Kazarian, Sergei G

    2017-01-15

    Hydroxyapatite and carbonate-substituted hydroxyapatite are widely used in bone tissue engineering and regenerative medicine. Both apatite materials were embedded into recently developed ceramic/polymer composites, subjected to Simulated Body Fluid (SBF) for 30days and characterized using ATR-FTIR spectroscopic imaging to assess their behaviour and structures. The specific aim was to detect the transition phases between both types of hydroxyapatite during the test and to analyze the surface modification caused by SBF. ATR-FTIR spectroscopic imaging was successfully applied to characterise changes in the hydroxyapatite lattice due to the elastic properties of the scaffolds. It was observed that SBF treatment caused a replacement of phosphates in the lattice of non-substituted hydroxyapatite by carbonate ions. A detailed study excluded the formation of pure A type carbonate apatite. In turn, CO3(2-) content in synthetic carbonate-substituted hydroxyapatite decreased. The usefulness of ATR-FTIR spectroscopic imaging studies in the evaluation of elastic and porous β-glucan hydroxyapatite composites has been demonstrated.

  6. Structural transformation of synthetic hydroxyapatite under simulated in vivo conditions studied with ATR-FTIR spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Sroka-Bartnicka, Anna; Borkowski, Leszek; Ginalska, Grazyna; Ślósarczyk, Anna; Kazarian, Sergei G.

    2017-01-01

    Hydroxyapatite and carbonate-substituted hydroxyapatite are widely used in bone tissue engineering and regenerative medicine. Both apatite materials were embedded into recently developed ceramic/polymer composites, subjected to Simulated Body Fluid (SBF) for 30 days and characterized using ATR-FTIR spectroscopic imaging to assess their behaviour and structures. The specific aim was to detect the transition phases between both types of hydroxyapatite during the test and to analyze the surface modification caused by SBF. ATR-FTIR spectroscopic imaging was successfully applied to characterise changes in the hydroxyapatite lattice due to the elastic properties of the scaffolds. It was observed that SBF treatment caused a replacement of phosphates in the lattice of non-substituted hydroxyapatite by carbonate ions. A detailed study excluded the formation of pure A type carbonate apatite. In turn, CO32- content in synthetic carbonate-substituted hydroxyapatite decreased. The usefulness of ATR-FTIR spectroscopic imaging studies in the evaluation of elastic and porous β-glucan hydroxyapatite composites has been demonstrated.

  7. Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study

    SciTech Connect

    Redondo, Pilar; Largo, Antonio; Vega-Vega, Álvaro; Barrientos, Carmen

    2015-05-14

    The structure and spectroscopic parameters of the most relevant [C,H,N,Zn] isomers have been studied employing high-level quantum chemical methods. For each isomer, we provide predictions for their molecular structure, thermodynamic stabilities as well as vibrational and rotational spectroscopic parameters which could eventually help in their experimental detection. In addition, we have carried out a detailed study of the bonding situations by means of a topological analysis of the electron density in the framework of the Bader’s quantum theory of atoms in molecules. The analysis of the relative stabilities and spectroscopic parameters suggests two linear isomers of the neutral [C,H,N,Zn] composition, namely, cyanidehydridezinc HZnCN ({sup 1}Σ) and hydrideisocyanidezinc HZnNC ({sup 1}Σ), as possible candidates for experimental detections. For the cationic [C,H,N,Zn]{sup +} composition, the most stable isomers are the ion-molecule complexes arising from the direct interaction of the zinc cation with either the nitrogen or carbon atom of either hydrogen cyanide or hydrogen isocyanide, namely, HCNZn{sup +} ({sup 2}Σ) and HCNZn{sup +} ({sup 2}Σ)

  8. Electrochemical and spectroscopic studies of some less stable oxidation states of selected lanthanide and actinide elements

    SciTech Connect

    Hobart, D. E.

    1981-06-01

    Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltammetry at microelectrodes was used in conjunction with spectroelectrochemistry for the study of redox couples. Additional analytical techniques were used. The formal reduction potential (E/sup 0/') values of the M(III)/M(II) redox couples in 1 M KCl at pH 6 were -0.34 +- 0.01 V for Eu, -1.18 +- 0.01 V for Yb, and -1.50 +- 0.01 V for Sm. Spectropotentiostatic determination of E/sup 0/' for the Eu(III)/Eu(II) redox couple yielded a value of -0.391 +- 0.005 V. Spectropotentiostatic measurement of the Ce(IV)/Ce(III) redox couple in concentrated carbonate solution gave E/sup 0/' equal to 0.051 +- 0.005 V, which is about 1.7 V less positive than the E/sup 0/' value in noncomplexing solution. This same difference in potential was observed for the E/sup 0/' values of the Pr(IV)/Pr(III) and Tb(IV)/Tb(III) redox couples in carbonate solution, and thus Pr(IV) and Tb(IV) were stabilized in this medium. The U(VI)/U(V)/U(IV) and U(IV)/U(III) redox couples were studied in 1 M KCl at OTE's. Spectropotentiostatic measurement of the Np(VI)/Np(V) redox couple in 1 M HClO/sub 4/ gave an E/sup 0/' value of 1.140 +- 0.005 V. An E/sup 0/' value of 0.46 +- 0.01 V for the Np(VII)/Np(VI) couple was found by voltammetry. Oxidation of Am(III) was studied in concentrated carbonate solution, and a reversible cyclic voltammogram for the Am(IV)/Am(III) couple yielded E/sup 0/' = 0.92 +- 0.01 V in this medium; this value was used to estimate the standard reduction potential (E/sup 0/) of the couple as 2.62 +- 0.01 V. Attempts to oxidize Cm(III) in concentrated carbonate solution were not successful which suggests that the predicted E/sup 0/ value for the Cm(IV)/Cm(III) redox couple may be in error.

  9. Femtosecond electron diffraction and spectroscopic studies of a solid state organic chemical reaction

    NASA Astrophysics Data System (ADS)

    Jean-Ruel, Hubert

    Photochromic diarylethene molecules are excellent model systems for studying electrocyclic reactions, in addition to having important technological applications in optoelectronics. The photoinduced ring-closing reaction in a crystalline photochromic diarylethene derivative was fully resolved using the complementary techniques of transient absorption spectroscopy and femtosecond electron crystallography. These studies are detailed in this thesis, together with the associated technical developments which enabled them. Importantly, the time-resolved crystallographic investigation reported here represents a highly significant proof-of-principle experiment. It constitutes the first study directly probing the molecular structural changes associated with an organic chemical reaction with sub-picosecond temporal and atomic spatial resolution---to follow the primary motions directing chemistry. In terms of technological development, the most important advance reported is the implementation of a radio frequency rebunching system capable of producing femtosecond electron pulses of exceptional brightness. The temporal resolution of this newly developed electron source was fully characterized using laser ponderomotive scattering, confirming a 435 +/- 75 fs instrument response time with 0.20 pC bunches. The ultrafast spectroscopic and crystallographic measurements were both achieved by exploiting the photoreversibility of diarylethene. The transient absorption study was first performed, after developing a novel robust acquisition scheme for thermally irreversible reactions in the solid state. It revealed the formation of an open-ring excited state intermediate, following photoexcitation of the open-ring isomer with an ultraviolet laser pulse, with a time constant of approximately 200 fs. The actual ring closing was found to occur from this intermediate with a time constant of 5.3 +/- 0.3 ps. The femtosecond diffraction measurements were then performed using multiple crystal

  10. The biocompatibility of carbon hydroxyapatite/β-glucan composite for bone tissue engineering studied with Raman and FTIR spectroscopic imaging.

    PubMed

    Sroka-Bartnicka, Anna; Kimber, James A; Borkowski, Leszek; Pawlowska, Marta; Polkowska, Izabela; Kalisz, Grzegorz; Belcarz, Anna; Jozwiak, Krzysztof; Ginalska, Grazyna; Kazarian, Sergei G

    2015-10-01

    The spectroscopic approaches of FTIR imaging and Raman mapping were applied to the characterisation of a new carbon hydroxyapatite/β-glucan composite developed for bone tissue engineering. The composite is an artificial bone material with an apatite-forming ability for the bone repair process. Rabbit bone samples were tested with an implanted bioactive material for a period of several months. Using spectroscopic and chemometric methods, we were able to determine the presence of amides and phosphates and the distribution of lipid-rich domains in the bone tissue, providing an assessment of the composite's bioactivity. Samples were also imaged in transmission using an infrared microscope combined with a focal plane array detector. CaF2 lenses were also used on the infrared microscope to improve spectral quality by reducing scattering artefacts, improving chemometric analysis. The presence of collagen and lipids at the bone/composite interface confirmed biocompatibility and demonstrate the suitability of FTIR microscopic imaging with lenses in studying these samples. It confirmed that the composite is a very good background for collagen growth and increases collagen maturity with the time of the bone growth process. The results indicate the bioactive and biocompatible properties of this composite and demonstrate how Raman and FTIR spectroscopic imaging have been used as an effective tool for tissue characterisation.

  11. Raman spectroscopic study of the photoprotection of extremophilic microbes against ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Moeller, R.; Jorge Villar, S. E.; Horneck, G.; Stackebrandt, E.

    2006-12-01

    Extremophiles use a range of pigments for protection against low-wavelength radiation in exposed terrestrial habitats and photoaccessory materials are synthesized for the effective harnessing of photosynthetically active radiation. Raman spectroscopy has been demonstrated to be a useful probe for information on the survival strategies employed by extremophilic bacteria through the identification of key biomolecular signatures of the suite of protective chemicals synthesized by the organisms in stressed environments. Raman spectroscopic analyses of Bacillus spp. spores, Bacillus atrophaeus (DSM 675: deep red) and Bacillus subtilis (DSM 5611: light grey and DSM 7264: dark grey), Deinococcus radiodurans (pink) and Natronomonas pharaonis (red), of visually different pigmentation showed the presence of different carotenoids and other protectant biomolecules, which assist microorganisms against UVA radiation. The implications for the survival of extremophilic microbes in extraterrestrial habitats and for the detection of the protectant biomolecules by remote, robotic Raman spectroscopic instrumentation in an astrobiological search for life context are discussed.

  12. Spectroscopic study of the strontium AM binaries HD 434 and 41 Sex A

    NASA Astrophysics Data System (ADS)

    Sreedhar Rao, S.; Abhyankar, K. D.

    1992-10-01

    Improved spectroscopic orbital elements of the single-line Am binary HD 434 are presented, and cover large gaps in the radial velocity curve obtained earlier by Hube and Gulliver (1985). The MK morphology of the spectrum of HD 434 is examined, and the classification of its metallic line types in the violet and blue regions, along with its revised K- and H-line spectral types, are given for the first time. The strontium anomaly in its spectrum is discussed. 41 Sex A is found to be a prototype of an Am star exhibiting transitional characteristics, forming an evolutionary link between Ap and Am groups of CP stars. Its spectroscopic orbital elements are confirmed using our own velocities. The MK morphology of its spectrum and its spectral line behavior, especially that of the Sr II 4077 line, are briefly discussed.

  13. Study on Biological Effects of La(3+) on Rat Liver Mitochondria by Microcalorimetric and Spectroscopic Methods.

    PubMed

    Wu, Man; Gao, Jia-Ling; Feng, Zhi-Jiang; Liu, Wen; Zhang, Ye-Zhong; Liu, Yi; Dai, Jie

    2015-09-01

    The effects of lanthanum on heat production of mitochondria isolated from Wistar rat liver were investigated with microcalorimetry; simultaneously, the effects on mitochondrial swelling and membrane potential (Δψ) were determined by spectroscopic methods. La(3+) showed only inhibitory action on mitochondrial energy turnover with IC50 being 55.8 μmol L(-1). In the spectroscopic experiments, La(3+), like Ca(2+), induced rat liver mitochondrial swelling and decreased membrane potential (Δψ), which was inhibited by the specific permeability transition inhibitor, cyclosporine A (CsA). The induction ability of La(3+) was stronger than that of Ca(2+). These results demonstrated that La(3+) had some biotoxicity effect on mitochondria; the effects of La(3+) and Ca(2+) on rat liver mitochondrial membrane permeability transition (MPT) are different, and La represents toxic action rather than Ca analogy.

  14. 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.

  15. Time resolved spectroscopic investigation of SiD2 + D2: kinetic study

    NASA Astrophysics Data System (ADS)

    Al-Rubaiey, Najem A.; Walsh, Robin

    2017-03-01

    Silylenes (silanediyls) have made an important impact on organosilicon chemistry even if it is of more recent foundation than carbenes in organic chemistry and much less complete. These species are highly reactive intermediates. They play a central role in the chemical vapour deposition (CVD) of various silicon-containing thin films which have a technological importance in microelectronics as well as in the dry etching processes of silicon wafers. Spectroscopic methods have been developed to observe these species, a necessary pre-requisite to their direct monitoring. In this work, deuterated phenylsilane precursor, PhSiD3 was chosen for SiD2 because its analogue phenylsilane, PhSiH3 proved to be a good precursor for SiH2 and the high quality decay signals observed revealed that SiD2 be readily detected from PhSiD3 and that if other decomposition pathways (e.g. PhSiD + D2) are occurring, they do not effect measurements of the rate constants for SiD2. The absorption spectrum of SiD2 formed from the flash photolysis of a mixture of PhSiD3 and SF6 at 193nm were found in the region 17384-17391 cm-1 with strong band at 17387.07 cm-1. This single rotational line of pQ1 was chosen to monitor SiD2 removal. Time-resolved studies of SiD2 have been carried out to obtain rate constants for its bimolecular reactions with D2. The reactions were studied over the pressure range 5-100 Torr (in SF6 bath gas) at four temperatures in the range 298-498K. Single decay from 10 photolysis laser shots were averaged and found to give reasonable first-order kinetics fits. Second order kinetics were obtained by pressure dependence of the pseudo first order decay constants and substance D2 pressures within experimental error. The reaction was found to be weakly pressure dependent at all temperatures, consistent with a third-body mediated association process. In addition, SiH2+ H2 reaction is approximately ca. 60% faster than SiD2+D2 reaction. Theoretical extrapolations (using Lindemann

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

    NASA Astrophysics Data System (ADS)

    Manso, M.; Carvalho, M. L.

    2009-06-01

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

  17. Scanning tunneling spectroscopic evidence for a magnetic field-revealed microscopic order in the high-TC superconductor YBa2Cu3O7-δ

    NASA Astrophysics Data System (ADS)

    Beyer, A. D.; Grinolds, M. S.; Teague, M. L.; Yeh, N.-C.; Tajima, S.

    2009-03-01

    We present spatially resolved scanning tunneling spectroscopic measurements of YBa2Cu3O7-δ as a function of magnetic field and at T<field-enhanced conductance modulations with periods of 3.4+0.5 and 7.3+0.5 lattice constants. Energy histograms of QP spectra show a significant shift from SC to primarily PG-like spectra and a growing enhancement of spectral weight at δ' as magnetic field increases, implying a significant interplay between SC and a field-enhanced microscopic order. Ref.: Beyer, et.al. [arxiv:0808.3016].

  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. Structural and spectroscopical study of crystals of 1,3,4-oxadiazole derivatives at high pressure

    NASA Astrophysics Data System (ADS)

    Franco González, Olga

    2002-07-01

    In recent years the search for new materials of technological interest has given new impulses to the study of organic compounds. Organic substances possess a great number of advantages such as the possibility to adjust their properties for a given purpose by different chemical and physical techniques in the preparation process. Oxadiazole derivatives are interesting due to their use as material for light emitting diodes (LED) as well as scintillators. The physical properties of a solid depend on its structure. Different structures induce different intra- and intermolecular interactions. An advantageous method to modify the intra- as well as the intermolecular interactions of a given substance is the application of high pressure. Furthermore, using this method the chemical features of the compound are not influenced. We have investigated the influence of high pressure and high temperature on the super-molecular structure of several oxadiazole derivatives in crystalline state. From the results of this investigation an equation of state for these crystals was determined. Furthermore, the spectroscopical features of these materials under high pressure were characterized. Die Suche nach neuen Materialien von technischem Interesse hat in den letzten Jahren neue Antriebe zu der Untersuchung organischer Verbindungen gegeben. Organische Substanzen haben viele Vorteile wie z.B. die Möglichkeit, ihre Eigenschaften durch verschiedene chemische und physikalische Techniken im Herstellung-Prozess für ein bestimmtes Ziel zu modifizieren. Oxadiazolverbindungen sind interessant aufgrund ihrer Nutzung als Material für Licht emittierende Dioden und Scintillatoren. Die physikalischen Eigenschaften eines Festkörpers hängen von seiner Struktur ab. Unterschiedliche Strukturen entwickeln unterschiedliche intra- und intermolekülare Wechselwirkungen. Eine ausgezeichnete Weise, um sowohl die intra- als auch die intermolekularen Wechselwirkungen eines bestimmtes Stoffes zu beeinflussen

  20. FTIR spectroscopic study of the mechanism for the gas-phase reaction between ozone and tetramethylethylene

    SciTech Connect

    Niki, H.; Maker, P.D.; Savage, C.M.; Breitenbach, L.P.; Hurley, M.D.

    1987-02-12

    Long-path FTIR spectroscopic product studies were made of mixtures containing part-per-million concentrations of O/sub 3/ and (CH/sub 3/)/sub 2/C double bonded C(CH/sub 3/)/sub 2/ (TME) in 700 Torr of O/sub 2/-N/sub 2/ to determine the formation and reactions of the dimethyl-substituted Criegee intermediate (CH/sub 3/)/sub 2/COO expected from O/sub 3/ + TME ..-->.. (CH/sub 3/)/sub 2/COO + (CH/sub 3/)/sub 2/C double bonded O. The observed stoichiometry, ..delta..-(TME)/..delta..(O/sub 3/), was typically 1.7, and among the products were CO, CO/sub 2/, HCHO, CH/sub 3/OH, CH/sub 3/OOH, CH/sub 3/C(double bonded O)OH, CH/sub 3/C(double bonded O)OOH, (CH/sub 3/)/sub 2/C double bonded O, CH/sub 3/C(double bonded O)CHO, CH/sub 3/C(double bonded O)OCH/sub 3/, CH/sub 3/C(double bonded O)CH/sub 2/(OH), and products tentatively identified as (CH/sub 2/)/sub 2/C(OH)-C(CH/sub 3/)/sub 2/OOH AND CH/sub 3/C(double bonded O)CH/sub 2/(OOH). In addition, /sup 16/O- and /sup 18/O-labeled products were identified in /sup 18/O/sub 3/-TME-air mixtures, and the effects of added HCHO, CH/sub 3/CHO, and NO/sub 2/ (or /sup 15/NO/sub 2/) on the product distribution were determined. The results indicate that ca. 25% of the (CH/sub 3/)/sub 2/COO moiety formed was thermally stable, and that the remainder largely dissociated to yield the following free radicals, i.e., (CH/sub 3/)/sub 2/COO ..-->.. CH/sub 3/C(OOH)double bonded CH/sub 2/ ..-->.. CH/sub 3/C(double bonded O)CH/sub 2/ + HO. The HO-initiated oxidation of TME was shown to account for the excess consumption of TME over O/sub 3/ as well as for some of the major products observed.