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1

Rapid Flow Analysis Studies with Spectroscopic Detectors  

Microsoft Academic Search

A rapid flow analysis study based on segmented flow and flow injection principles is described in this thesis. The main objective of this study was to establish the response characteristics in continuous flow analysis systems in order to improve sampling rates with several types of spectroscopic detectors. It was found from flame photometric studies that non-segmented flowing streams are applicable

Amlius Thalib

1984-01-01

2

Rapid Flow Analysis Studies with Spectroscopic Detectors.  

NASA Astrophysics Data System (ADS)

A rapid flow analysis study based on segmented flow and flow injection principles is described in this thesis. The main objective of this study was to establish the response characteristics in continuous flow analysis systems in order to improve sampling rates with several types of spectroscopic detectors. It was found from flame photometric studies that non-segmented flowing streams are applicable to rapid flow analysis with automatic sample aspiration. Calcium was used as a typical example and determined at sampling rates up to 360 h('-1) with a detection limit of 0.05 mg L(' -1). A rapid flow system is reported using direct aspiration for AAS analysis with both manual injection and automatic aspiration techniques, and found to give sampling rates of up to 600-720 samples h('-1). Speed of analysis was reduced by about 50% when using an external peristaltic pump in the flow system design, due to increased sample dispersion. A novel aspect of a rapid flow injection approach reported with ICPAES detection includes the method of injecting samples via a peristaltic pump with simultaneous computer data processing. Determination of serum cations (Na, K, Ca, Mg and Fe) was demonstrated as an example of an application of the technique at sampling rates of 240 h('-1). Precision and detection limits for 13 elements in a single standard solution are reported. The use of automated aspiration sampling is also reported in this method for comparison. Further studies on flow characteristics were carried out by a combination of the rapid flow system with very short sampling times as low as 2 seconds using UV-visible spectrophotometric detection. Analysis of human blood serum samples was used as an example where total protein and inorganic phosphate were determined at sampling rates of 240 h('-1) and 360 h('-1) respectively. The novel aspects of the results from these studies include the very rapid sample throughput developed with simple and inexpensive experimental approaches in comparison to bubble gating and loop injection techniques. Part of this thesis has already been published and the abstracts are presented in the Appendix.

Thalib, Amlius

3

A study of colloids in deep groundwater using spectroscopic analysis  

NASA Astrophysics Data System (ADS)

In groundwater, colloids play an important role as carriers of various elements. The effect of colloids on behavior of radioactive nuclides must be evaluated with respect to safety assessment for geological disposal of high-level radioactive waste. However, study of the role of colloids in groundwater at depths greater than several hundred meters is still difficult due to lack of a suitable method which can collect and analyze colloids with a guarantee of quality of sample. The most serious problems on the method are the artificial impact of drilling and the chemical alteration during collection and analysis. The aim of this study is to develop a method that meets the requirements for understanding the chemical properties of colloids in groundwater. The Mizunami Underground Research Laboratory (MIU) is a facility used for geoscientific researches by the Japan Atomic Energy Agency (JAEA). Two boreholes at the MIU were used to evaluate groundwater quality for colloid studies. One is a horizontal borehole in artesian condition (07MI07: length 55 m) drilled from the horizontal gallery excavated at a depth of 200 m. The other one is a deep inclined borehole (MIZ-1: length 1300 m) drilled from the surface. The 07MI07 was drilled with fresh water and without mud fluid, whereas the MIZ-1 was drilled with mud fluid to prevent collapse. Colloids of the 07MI07 were collected using ultrafiltration and maintaining both pressurized and anaerobic conditions. On the other hand, sample collection in the MIZ-1 used ultrafiltration, but only anaerobic condition was maintained. Membrane filters (pore size 10 kDa) with colloids were dried under Ar gas atmosphere. Observation of colloids was conducted using scanning electron microscopy-energy dispersive X-ray analyzer (SEM-EDX), attenuated total reflectance infrared spectroscopy (ATR-IR), X-ray absorption fine structure (XAFS) of Fe K-edge, and transmission electron microscopy-energy dispersive X-ray analyzer (TEM-EDX). For SEM-EDX analysis, results of fluorescence mapping of the MIZ-1 show existence of inorganic particles (>1 µm) mainly consist of Al, Si, and Fe, in the matrix consist of organic C. For the 07MI07, these inorganic particles are depleted with Fe. Colloids consist of organic C are also observed in the 07MI07. For both boreholes, the ATR-IR spectra of colloids are similar to that of humic substance. It is suggested by XAFS analysis that Fe(III) is the dominant chemical state of Fe in all samples. For the MIZ-1, a large amount of amorphous Fe hydroxides particles with a size of 50 nm are observed by TEM-EDX, but not for the 07MI07. It is expected that Fe(III) are supplied from drill pit and mud fluid. The artificial Fe colloids in the MIZ-1 remain in groundwater after drilling, whereas the artificial Fe of the 07MI07 has been mostly flushed by inflow of water. Our results suggest that using the borehole drilled from the underground facility can suppress the degree of artificial impact of drilling. It is concluded that the combination of ultrafiltration and the spectroscopic analyses employed here can provide information of chemical properties of colloids and suppress chemical alteration during collection and analysis.

Yamamoto, Y.; Aosai, D.; Mizuno, T.; Watanabe, K.; Kogure, T.; Suzuki, Y.

2010-12-01

4

Spectroscopic studies and normal coordinate analysis of bilirubin  

NASA Astrophysics Data System (ADS)

The infrared spectrum of bilirubin has been recorded in the spectral region 200-4000 cm -1. The Raman spectrum has also been recorded using the second harmonic (530 nm) radiation of a 200 mW Nd-YAG laser. In order to confirm the vibrational assignment of the bands obtained from experimental observation, a normal coordinate analysis has been carried out using the semi-empirical AM1 method through MOPAC 5.1 computer program. Electronic absorption spectrum of bilirubin dissolved in CHCl 3 has been recorded in the spectral region 300-600 nm. A broad spectrum is observed with peak maxima at 454.2 nm. The photoacoustic spectrum of this molecule (in the powder form) has also been recorded for the first time which shows certain discrete features.

Rai, Amareshwar Kumar; Rai, S. B.; Rai, D. K.; Singh, V. B.

2002-08-01

5

A study of colloids in deep groundwater using spectroscopic analysis  

Microsoft Academic Search

In groundwater, colloids play an important role as carriers of various elements. The effect of colloids on behavior of radioactive nuclides must be evaluated with respect to safety assessment for geological disposal of high-level radioactive waste. However, study of the role of colloids in groundwater at depths greater than several hundred meters is still difficult due to lack of a

Y. Yamamoto; D. Aosai; T. Mizuno; K. Watanabe; T. Kogure; Y. Suzuki

2010-01-01

6

Comparative study of ATR and transflection IR spectroscopic techniques for the analysis of hallucinogenic mushrooms.  

PubMed

This paper compares the use of ATR and transflection spectroscopic techniques for the qualitative analysis of psilocin extracted from hallucinogenic mushrooms and control spiked mushrooms. Both techniques gave comparable results and agreed with prior GC/MS analysis of the actual case samples. PMID:19969433

Koçak, A; De Cotiis, L M; Hoffman, D B

2010-02-25

7

[The spectroscopic study of topaz].  

PubMed

In this paper, the natural gem material--Topaz (colorless transparent samples and reactor irradiation induced blue color samples) was studied on the spectroscopic analysis of Fourier transformation infrared spectrum (FTIR) and FT-Raman spectrum. The structure of topaz consists of OH groups and SiO4 groups. Si-O vibration spectrum was characterized with the group theoretical analysis. OH stretching modes of vibration showed many changes among the different color samples, the reason of the changes was explained. The color origin was preliminary investigated by ultra-violet and visible absorption spectrum. PMID:12953446

Wang, B; Tu, J

2000-02-01

8

Studying Light: Spectroscopes  

NSDL National Science Digital Library

In this activity about spectroscopy, learners build a spectroscope, learn about graphing spectra, and then identify elements in gas tubes using their spectra. The activity concludes as learners graph the spectra of different materials. Essential materials required for this activity include spectrum light tubes, the power source for spectrum light tubes, and diffraction grating material.

9

Synthesis, spectroscopic studies, and AFM analysis of Ho3+ doped zirconium oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Nanometer sized crystals has attracted a lot of attention in the recent years because of the size dependent optical and electrical properties. Rare-earth ions in insulating hosts find use in a variety of applications, including phosphors for fluorescence lighting displays, monitors, lasers, fiber optic communication, biolabeling, bioimaging and solar-energy converters. Nanocrystals of trivalent holmium ion doped zirconium oxide crystals have been synthesized by using simple synthetic method. Spectroscopic studies of these nanocrystals have been conducted using visible and infrared laser excitation. Size distribution of the nanoparticles will also be discussed using atomic force microscope.

Patel, Darayas; King, Newton; Mingo, Courtney

2009-02-01

10

Spectroscopic Analysis of H? Dots  

NASA Astrophysics Data System (ADS)

We present spectroscopic measurements of ~200 faint point sources of emission - called H? dots - found in narrow-band images taken for the ALFALFA H? project. Our image analysis catalogs emission-line sources that are not optically associated with the target ALFALFA galaxy. Analyzing spectra of these sources, we find isolated extragalactic HII regions, ultra-low luminosity dwarf galaxies, background (higher redshift) galaxies, and QSOs. We give a summary of the photometric and spectroscopic properties of the full sample of H? dots discovered to date. We also illustrate why these objects are of astrophysical interest. For example, using coarse oxygen abundance measurements of the low luminosity dwarf galaxies, we detect signs of a possible flattening in the local Luminosity-Metallicity relation. We also find luminous [O III]-detected star-forming galaxies at z ~ 0.32 with unusually low oxygen abundances.

Feddersen, Jesse; Salzer, J. J.; Gronwall, C.

2013-06-01

11

Integrated Spectroscopic Studies of Mil03346.  

National Technical Information Service (NTIS)

Spectroscopic studies of the SNC meteorites continue to be of great interest because they provide the only 'ground truth' available for ongoing Mossbauer, thermal emittance, MidIR, nearIR, and visible spectral analysis of the martian surface. We present h...

M. D. Dyar C. M. Pieters T. Hiroi M. D. Lane

2005-01-01

12

Quantum chemical computations, vibrational spectroscopic studies, NLO and NBO/NLMO analysis of o-chlorobenzohydrazide.  

PubMed

The molecular vibrations of o-chlorobenzohydrazide (OCBH) have been investigated in polycrystalline sample, at room temperature, by recording Fourier transform infrared (FT-IR) and FT-Raman spectroscopies. The complete vibrational assignment and analysis of the fundamental modes was carried out using the experimental data and quantum chemical studies. The observed vibrational data were compared with the wavenumbers derived theoretically for the optimized geometry of the compound from the HF and DFT/B3LYP calculations employing 6-311++G(d,p) basis set. The (1)H and (13)C NMR chemical shifts have been simulated. Thermodynamic properties have been calculated at different temperatures. HOMO-LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. PMID:24727163

Gobinath, E; Xavier, R John

2014-08-14

13

Spectroscopic, thermal analysis and DFT computational studies of salen-type Schiff base complexes  

NASA Astrophysics Data System (ADS)

A new series of metal(II) complexes of Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) have been synthesized from a salen-type Schiff base ligand derived from o-vanillin and 4-methyl-1,2-phenylenediamine and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, 13C NMR and EI-mass), molar conductance measurements and thermal analysis techniques. Coats-Redfern method has been utilized to calculate the kinetic and thermodynamic parameters of the metal complexes. The molecular geometry, Mulliken atomic charges of the studied compounds were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The theoretical 13C chemical shift results of the studied compounds have been calculated at the B3LYP, PBEPBE and PW91PW91 methods and standard 6-311+G(d,p) basis set starting from optimized geometry. The comparison of the results indicates that B3LYP/6-311+G(d,p) yields good agreement with the observed chemical shifts. The measured low molar conductance values in DMF indicate that the metal complexes are non-electrolytes. The spectral and thermal analysis reveals that all complexes have octahedral geometry except Cu(II) complex which can attain the square planner arrangement. The presence of lattice and coordinated water molecules are indicated by thermograms of the complexes. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps.

Ebrahimi, Hossein Pasha; Hadi, Jabbar S.; Abdulnabi, Zuhair A.; Bolandnazar, Zeinab

2014-01-01

14

Spectroscopic, thermal analysis and DFT computational studies of salen-type Schiff base complexes.  

PubMed

A new series of metal(II) complexes of Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) have been synthesized from a salen-type Schiff base ligand derived from o-vanillin and 4-methyl-1,2-phenylenediamine and characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR, (13)C NMR and EI-mass), molar conductance measurements and thermal analysis techniques. Coats-Redfern method has been utilized to calculate the kinetic and thermodynamic parameters of the metal complexes. The molecular geometry, Mulliken atomic charges of the studied compounds were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The theoretical (13)C chemical shift results of the studied compounds have been calculated at the B3LYP, PBEPBE and PW91PW91 methods and standard 6-311+G(d,p) basis set starting from optimized geometry. The comparison of the results indicates that B3LYP/6-311+G(d,p) yields good agreement with the observed chemical shifts. The measured low molar conductance values in DMF indicate that the metal complexes are non-electrolytes. The spectral and thermal analysis reveals that all complexes have octahedral geometry except Cu(II) complex which can attain the square planner arrangement. The presence of lattice and coordinated water molecules are indicated by thermograms of the complexes. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps. PMID:24021948

Ebrahimi, Hossein Pasha; Hadi, Jabbar S; Abdulnabi, Zuhair A; Bolandnazar, Zeinab

2014-01-01

15

Non-destructive Analysis of Buried Interfaces and Surface Layers: X-Ray Emission Spectroscopic Study  

NASA Astrophysics Data System (ADS)

Soft X-ray emission spectroscopy (SXES) and extended X-ray emission fine structure (EXEFS) studies have been carried out on a heat-treated thin-film(Ni)/substrate(Si, SiC) contact system using a conventional X-ray micro-analysis (XMA) apparatus. We have successfully deduced information either the chemical bonding or atomic configuration by the former and the latter, respectively. Also, we have succeeded in analyzing an interface buried rather deep below an overlayer, e.g., more than a hundred nm. This is due to the fact that both an X-ray production depth of an energetic electron is much larger than the mean free path of an energetic electron and the mean free path of an X-ray photon in a solid is large. Namely, in the surface, or interface layer, Ni2Si and NiSi2 formation have been clarified for heat-treated Ni/SiC and Ni/Si systems, respectively.

Iwami, Motohiro; Hirai, Masaaki; Kusaka, Masahiko; Morii, Takashi

2003-07-01

16

Thermal treatment of whewellite—a thermal analysis and Raman spectroscopic study  

Microsoft Academic Search

Thermal transformations of natural calcium oxalate monohydrate known in mineralogy as whewellite have been undertaken using a combination of thermal analysis and Raman microscopy with the use of a thermal stage. High resolution thermogravimetry shows that three mass loss steps occur at 162, 479 and 684°C.Evolved gas mass spectrometry shows that water is evolved in the first step and carbon

Ray L Frost; Matt L Weier

2004-01-01

17

Spectroscopic studies and molecular orbital analysis on platinanaphthalenes and ring-fused B-N platinanaphthalenes  

NASA Astrophysics Data System (ADS)

The electronic structure and properties of the platinanaphthalenes, and ring-fused B-N platinanaphthalenes isomers have been explored using the hybrid density functional mpw1pw91 theory. The energetic aspect shows that stability of Ptb and Pta isomers are isoenergetic in platinanaphthalenes. On the other hand, BNa1 isomer is the most stable isomer of ring-fused B-N platinanaphthalenes. This is compatible with principles of minimum energy and minimum polarizability in ring-fused B-N platinanaphthalenes. Molecular orbital analysis shows increasing of hardness in ring-fused B-N platinanaphthalenes isomers. Also, electronic spectra analysis indicates that, in all the molecules HOMO-1 ? LUMO transition makes the major contribution in most intense electronic transition.

Ghiasi, Reza; Ara, Taherh Jahan; Hakimyoun, Amir Hossein

2014-04-01

18

Vibrational spectroscopic analysis of 2-bromobenzoic and anthranilic acids: A combined experimental and theoretical study  

NASA Astrophysics Data System (ADS)

In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100-4000 cm -1 and 50-4000 cm -1 respectively, for the title molecules. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartee-Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The effects due to the substitutions of amino group and halogen bond were investigated. The results of the calculations were applied to simulate spectra of the title compounds, which show excellent agreement with observed spectra.

Govindarajan, M.; Ganasan, K.; Periandy, S.; Mohan, S.; Tedlamelekot, F.

2011-09-01

19

Microwave spectroscopic studies of molecular recognition: Analysis of diastereomeric interactions between ethanol and oxirane derivatives  

NASA Astrophysics Data System (ADS)

High resolution microwave spectroscopy complimented by ab initio calculations has been used to elucidate the diastereomeric interactions in a set of small model complexes. Ethanol, a transient chiral alcohol, was combined with oxirane (achiral), methyl-oxiraneootnotetextmark[1] (1 stereocenter) and trans-2,3-dimethyloxirane (2 stereocenters) to form hydrogen-bonded 1:1 complexes. The rotational constants of two conformers of ethanoloxirane, six conformers of ethanolmethyl-oxirane and three conformers of ethanoltrans-2,3-dimethyloxirane have been determined and the relative stability order of the conformers has been established. The dependence of the observed intensity on pressure, nozzle temperature and different carrier gases has been investigated for the case of ethanoltrans-2,3-dimethyloxirane to give a first insight into the kinetical and thermodynamical influence on the formation of different conformers. The step-by-step methyl addition to oxirane helps to unravel the diastereomeric interactions at play via analysis of the subtle energy differences between each set of conformers, allowing for a detailed understanding of molecular recognition in this benchmark system.ootnotetextmark[1]Nicole Borho, Yunjie Xu, Angew. Chem., 2006, (VIP paper, Published Online: 17 Nov 2006, DOI: 10.1002/anie.200603809).

Borho, Nicole; Xu, Yunjie

2007-06-01

20

Vibrational spectroscopic investigation and conformational analysis of 1-heptylamine: A comparative density functional study  

NASA Astrophysics Data System (ADS)

FT-IR and Raman spectra of 1-heptylamine (1-ha) have been recorded in the region of 4000-10 cm-1 and 4000-50 cm-1, respectively. The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1-ha (C7H17N) have been examined by means of the Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) method together with the 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments have been made on the basis of potential energy distribution (PED) and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 1-ha have been predicted. Calculations have been carried out with the possible ten conformational isomers (TT, TG, GT, GT1, GG1, GG2, GG3, GG4, GG5, GG6; T and G denote trans and gauge) of 1-ha, both in gas phase and in solution. Solvent effects have theoretically been investigated using benzene and methanol. All results indicate that the B3LYP method provides satisfactory evidence for the prediction of vibrational frequencies and the TT isomer is the most stable form of 1-ha.

Tursun, Mahir; Ke?an, Gürkan; Parlak, Cemal; ?enyel, Mustafa

2013-10-01

21

Vibrational spectroscopic study and NBO analysis on tranexamic acid using DFT method.  

PubMed

In this work, we reported the vibrational spectra of tranexamic acid (TA) by experimental and quantum chemical calculation. The solid phase FT-Raman and FT-IR spectra of the title compound were recorded in the region 4000 cm(-1) to 100 cm(-1) and 4000 cm(-1) to 400 cm(-1) respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of TA in the ground state have been calculated by using density functional theory (DFT) B3LYP method with standard 6-31G(d,p) basis set. The scaled theoretical wavenumber showed very good agreement with the experimental values. The vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes. Stability of the molecule, arising from hyperconjugative interactions and charge delocalization, has been analyzed using Natural Bond Orbital (NBO) analysis. The results show that ED in the ?(*) and ?(*) antibonding orbitals and second order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The electrostatic potential mapped onto an isodensity surface has been obtained. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase. PMID:24747330

Muthu, S; Prabhakaran, A

2014-08-14

22

Vibrational spectroscopic study and NBO analysis on tranexamic acid using DFT method  

NASA Astrophysics Data System (ADS)

In this work, we reported the vibrational spectra of tranexamic acid (TA) by experimental and quantum chemical calculation. The solid phase FT-Raman and FT-IR spectra of the title compound were recorded in the region 4000 cm-1 to 100 cm-1 and 4000 cm-1 to 400 cm-1 respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of TA in the ground state have been calculated by using density functional theory (DFT) B3LYP method with standard 6-31G(d,p) basis set. The scaled theoretical wavenumber showed very good agreement with the experimental values. The vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes. Stability of the molecule, arising from hyperconjugative interactions and charge delocalization, has been analyzed using Natural Bond Orbital (NBO) analysis. The results show that ED in the ?* and ?* antibonding orbitals and second order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The electrostatic potential mapped onto an isodensity surface has been obtained. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase.

Muthu, S.; Prabhakaran, A.

2014-08-01

23

Vibrational Spectroscopic Investigation and Conformational Analysis of 1-HEPTYLAMINE: a Comparative Density Functional Study  

NASA Astrophysics Data System (ADS)

FT-IR and Raman spectra of 1-heptylamine (1-ha) were experimentally reported in the region of 4000-10 cm-1 and 4000-100 cm-1, respectively. The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1-ha (C7H17N) were theoretically examined by means of Becke-3-Lee-Yang-Parr (B3-LYP) density functional theory (DFT) method together with 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments were made on the basis of potential energy distribution (PED) calculated and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 1-ha were predicted. Calculations were carried out with the possible ten conformational isomers (TT, TG, GT, GT1, GG1, GG2, GG3, GG4, GG5, GG6; T and G denote trans and gauge) of 1-ha, both in gas phase and in solution. Solvent effects were investigated using benzene and methanol. All results indicates that B3-LYP method provides satisfactory results for the prediction vibrational wavenumbers, TT isomer is the most stable form of 1-ha and the conformational energy barrier is independent of the solvent whereas the vibrational frequencies and assignments, IR and Raman intensities of 1-ha are solvent dependent.

Tursun, Mahir; Kesan, Gurkan; Parlak, Cemal; Senyel, Mustafa

2013-06-01

24

Application of comparative vibrational spectroscopic and mechanistic studies in analysis of fisetin structure  

NASA Astrophysics Data System (ADS)

This paper addresses experimental and theoretical research in fisetin (2-(3,4-dihydroxyphenyl)-3,7-dihydroxychromen-4-one) structure by means of experimental IR and Raman spectroscopies and mechanistic calculations. Density Functional Theory calculations, with M05-2X functional and the 6-311+G (2df, p) basis set implemented in the Gaussian 09 package, are performed with the aim to support molecular structure, vibrational bands' positions and their intensities. Potential energy distribution (PED) values and the description of the largest vibrational contributions to the normal modes are calculated. The most intense bands appear in the 1650-1500 cm -1 wavenumber region. This region involves a combination of the C dbnd O, C2 dbnd C3 and C-C stretching vibrational modes. Most of the bands in the 1500-1000 cm -1 range involve C-C stretching, O-C stretching and in-plane C-C-H, C-O-H, C-C-O and C-C-C bending vibrations of the rings. The region below 1000 cm -1 is characteristic to the combination of in plane C-C-C-H, H-C-C-H, C-C-C-C, C-C-O-C and out of plane O-C-C-C, C-C-O-C, C-C-C-C torsional modes. The Raman spectra of baicalein and quercetin were used for qualitative comparison with fisetin spectrum and verification of band assignments. The applied detailed vibrational spectral analysis and the assignments of the bands, proposed on the basis of fundamentals, reproduced the experimental results with high degree of accuracy.

Dimitri? Markovi?, Jasmina M.; Markovi?, Zoran S.; Milenkovi?, Dejan; Jeremi?, Svetlana

2011-12-01

25

FT-IR spectroscopic analysis to study the firing processes of prehistoric ceramics  

NASA Astrophysics Data System (ADS)

In this work, we present a FT-IR absorbance investigation on prehistoric ceramics with the aim of characterizing the phase transformations that occur during the cooking processes. The measurements were performed on several potteries belonging to the Middle Bronze Age excavated in the Catania hinterland (Sicily, Southern Italy). Based on the macroscopic observation, the samples may be distinguished on coarse and fine ceramics, and the petrographic study showed a strongly heterogeneous structure and composition. The results were compared with the data obtained by means of X-ray diffraction (XRD) and with the microscopic qualitative observations of the birefringence of the groundmass. The whole set of the data showed a firing temperature in the 800-900 °C range. The simultaneous presence in several samples of calcite and clay minerals and of new-formed Ca-silicates should be indicative of a quite primitive technological firing process with strong temperature variation inside the kiln.

Barone, G.; Crupi, V.; Longo, F.; Majolino, D.; Mazzoleni, P.; Tanasi, D.; Venuti, V.

2011-05-01

26

Multivariate curve resolution applied to the simultaneous analysis of electrochemical and spectroscopic data: study of the Cd(II)/glutathione-fragment system by voltammetry and circular dichroism spectroscopy.  

PubMed

Multivariate curve resolution with alternating least squares (MCR-ALS) is applied for the first time to the simultaneous analysis of electrochemical and spectroscopic data. Then, a data analysis is done with augmented matrices constituted by Differential Pulse Polarography and Circular Dichroism data submatrices. The use of proper, and different for each submatrix, constrains in the iterative ALS optimization allows to obtain chemically meaningful results constituted by a common matrix containing the concentration profiles, and two matrices with the pure electrochemical and spectroscopic signals. MCR-ALS is applied to the study of the complexation of Cd by Cys-Gly, a glutathione-fragment of great interest for understanding metal-phytochelatins complexation. PMID:17386631

Alberich, Arístides; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

2007-02-19

27

Frequency domain optical coherence tomography with subsequent depth resolved spectroscopic image analysis  

Microsoft Academic Search

We present a method to obtain additional depth resolved spectroscopic information from standard frequency domain optical coherence tomography (FDOCT) images. This method utilizes Fourier transforms of signal peaks within the complex FDOCT depth profiles to extract depth resolved spectroscopic information. For verification of the depth resolved spectroscopic image analysis method, theoretical simulations as well as experimental studies are demonstrated. Both

Christoph Kasseck; Volker Jaedicke; Nils C. Gerhardt; Hubert Welp; Martin R. Hofmann

2010-01-01

28

Spectroscopic chemical analysis methods and apparatus  

NASA Technical Reports Server (NTRS)

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted simultaneously with native fluorescence spectroscopy to provide high levels of sensitivity and specificity in the same instrument.

Hug, William F. (Inventor); Reid, Ray D. (Inventor)

2010-01-01

29

Spectroscopic chemical analysis methods and apparatus  

NASA Technical Reports Server (NTRS)

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted simultaneously with native fluorescence spectroscopy to provide high levels of sensitivity and specificity in the same instrument.

Hug, William F. (Inventor); Reid, Ray D. (Inventor)

2009-01-01

30

Studies related to Norway spruce galactoglucomannans: chemical synthesis, conformation analysis, NMR spectroscopic characterization, and molecular recognition of model compounds.  

PubMed

Galactoglucomannan (GGM) is a polysaccharide mainly consisting of mannose, glucose, and galactose. GGM is the most abundant hemicellulose in the Norway spruce (Picea abies), but is also found in the cell wall of flax seeds, tobacco plants, and kiwifruit. Although several applications for GGM polysaccharides have been developed in pulp and paper manufacturing and the food and medical industries, attempts to synthesize and study distinct fragments of this polysaccharide have not been reported previously. Herein, the synthesis of one of the core trisaccharide units of GGM together with a less-abundant tetrasaccharide fragment is described. In addition, detailed NMR spectroscopic characterization of the model compounds, comparison of the spectral data with natural GGM, investigation of the acetyl-group migration phenomena that takes place in the polysaccharide by using small model compounds, and a binding study between the tetrasaccharide model fragment and a galactose-binding protein (the toxin viscumin) are reported. PMID:23008171

Ekholm, Filip S; Ardá, Ana; Eklund, Patrik; André, Sabine; Gabius, Hans-Joachim; Jiménez-Barbero, Jesús; Leino, Reko

2012-11-01

31

Spectroscopic chemical analysis methods and apparatus  

NASA Technical Reports Server (NTRS)

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. Chemical analysis instruments employed in some embodiments include capillary and gel plane electrophoresis, capillary electrochromatography, high performance liquid chromatography, flow cytometry, flow cells for liquids and aerosols, and surface detection instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted along with photoluminescence spectroscopy (i.e. fluorescence and/or phosphorescence spectroscopy) to provide high levels of sensitivity and specificity in the same instrument.

Hug, William F. (Inventor); Reid, Ray D. (Inventor); Bhartia, Rohit (Inventor)

2013-01-01

32

Quadrupole resonance spectroscopic study of narcotic materials  

NASA Astrophysics Data System (ADS)

Bulk narcotic detection systems based upon Quadrupole Resonance Analysis (QRA) technology have a major advantage over imaging technologies, in that QRA is chemical-specific and consequently has a lower rate of false alarms. QRA is a magnetic resonance technology which occurs as a result of the inherent molecular properties of the atomic nuclei in crystalline and amorphous solids. The QRA response is characterized by 1) the precessional frequency of the nucleus, and 2) the nature of the electric field gradient experienced by the nucleus,due to its molecular environment. Another important detection parameter is linewidth, resonant quality. All of these parameters depend on sample purity and manufacturing process. Quantum Magnetics recently carried out a study on the QRA signatures of various narcotic materials with the support of the US Army, US Customs, and the Office of National Drug Control Policy. The aim of the study was to fully characterize the variation in QRA spectroscopic parameters of different samples of cocaine base and cocaine hydrochloride. The results from this study ar discussed here.

Rayner, Timothy J.; West, Rebecca; Garroway, Allen N.; Lyndquist, R.; Yesinowski, James P.

1997-02-01

33

Galaxy And Mass Assembly (GAMA): spectroscopic analysis  

NASA Astrophysics Data System (ADS)

The Galaxy And Mass Assembly (GAMA) survey is a multiwavelength photometric and spectroscopic survey, using the AAOmega spectrograph on the Anglo-Australian Telescope to obtain spectra for up to ˜300 000 galaxies over 280 deg2, to a limiting magnitude of rpet < 19.8 mag. The target galaxies are distributed over 0 < z ? 0.5 with a median redshift of z ? 0.2, although the redshift distribution includes a small number of systems, primarily quasars, at higher redshifts, up to and beyond z = 1. The redshift accuracy ranges from ?v ? 50 km s-1 to ?v ? 100 km s-1 depending on the signal-to-noise ratio of the spectrum. Here we describe the GAMA spectroscopic reduction and analysis pipeline. We present the steps involved in taking the raw two-dimensional spectroscopic images through to flux-calibrated one-dimensional spectra. The resulting GAMA spectra cover an observed wavelength range of 3750 ? ? ? 8850 Å at a resolution of R ? 1300. The final flux calibration is typically accurate to 10-20 per cent, although the reliability is worse at the extreme wavelength ends, and poorer in the blue than the red. We present details of the measurement of emission and absorption features in the GAMA spectra. These measurements are characterized through a variety of quality control analyses detailing the robustness and reliability of the measurements. We illustrate the quality of the measurements with a brief exploration of elementary emission line properties of the galaxies in the GAMA sample. We demonstrate the luminosity dependence of the Balmer decrement, consistent with previously published results, and explore further how Balmer decrement varies with galaxy mass and redshift. We also investigate the mass and redshift dependencies of the [N II]/H? versus [O III]/H? spectral diagnostic diagram, commonly used to discriminate between star forming and nuclear activity in galaxies.

Hopkins, A. M.; Driver, S. P.; Brough, S.; Owers, M. S.; Bauer, A. E.; Gunawardhana, M. L. P.; Cluver, M. E.; Colless, M.; Foster, C.; Lara-López, M. A.; Roseboom, I.; Sharp, R.; Steele, O.; Thomas, D.; Baldry, I. K.; Brown, M. J. I.; Liske, J.; Norberg, P.; Robotham, A. S. G.; Bamford, S.; Bland-Hawthorn, J.; Drinkwater, M. J.; Loveday, J.; Meyer, M.; Peacock, J. A.; Tuffs, R.; Agius, N.; Alpaslan, M.; Andrae, E.; Cameron, E.; Cole, S.; Ching, J. H. Y.; Christodoulou, L.; Conselice, C.; Croom, S.; Cross, N. J. G.; De Propris, R.; Delhaize, J.; Dunne, L.; Eales, S.; Ellis, S.; Frenk, C. S.; Graham, Alister W.; Grootes, M. W.; Häußler, B.; Heymans, C.; Hill, D.; Hoyle, B.; Hudson, M.; Jarvis, M.; Johansson, J.; Jones, D. H.; van Kampen, E.; Kelvin, L.; Kuijken, K.; López-Sánchez, Á.; Maddox, S.; Madore, B.; Maraston, C.; McNaught-Roberts, T.; Nichol, R. C.; Oliver, S.; Parkinson, H.; Penny, S.; Phillipps, S.; Pimbblet, K. A.; Ponman, T.; Popescu, C. C.; Prescott, M.; Proctor, R.; Sadler, E. M.; Sansom, A. E.; Seibert, M.; Staveley-Smith, L.; Sutherland, W.; Taylor, E.; Van Waerbeke, L.; Vázquez-Mata, J. A.; Warren, S.; Wijesinghe, D. B.; Wild, V.; Wilkins, S.

2013-04-01

34

Spectroscopic analysis of chromium bioremediation products  

NASA Astrophysics Data System (ADS)

Remediation of chromium contamination frequently involves reducing the toxic and soluble hexavalent form, Cr(VI), to the relatively harmless and mostly immobile trivalent state, Cr(III). The objective of this study is to identify the biogeochemical reactions that control in situ chromium reduction in the presence of different dominant electron acceptors, i.e., NO3-, Fe(III), and SO42-. It was hypothesized that indirect, abiotic reduction of Cr(VI) by reduced metabolic products [Fe(II) and sulfides] would dominate over direct enzymatic reduction by denitrifying, iron-reducing, or sulfate-reducing bacteria. It is further hypothesized that the enzymatic reduction of Cr(VI) would produce relatively pure chromium hydroxide precipitates, whereas indirect reduction would result in mixed Cr-Fe hydroxide solid phases. Flow-through columns containing homogenized sediments from the 100H site at Hanford, WA were subjected to nitrate-, sulfate- or iron-reducing conditions in the presence of 5 µM Cr(VI) and 5 mM lactate. Cr(VI) was depleted in the effluent solutions from the nitrate- and sulfate-reducing columns; however only a small amount of Cr(VI) was removed under iron-reducing conditions. Preliminary analysis of micro X-ray absorption spectra indicate that the untreated and iron-reducing column sediments contained pre-existing Cr in the form of primary minerals, e.g. chromite and/or Cr-bearing micas. However, there was an increase in the relative abundance of mixed-phase Cr-Fe hydroxides, i.e., Cr1-xFex(OH)3 in the nitrate- and sulfate-treated columns. A possible explanation for the observations is that the production of Fe(II) was enhanced under the nitrate- and sulfate- reducing conditions, and was most likely sulfide-driven in the latter case. The Fe(II) was subsequently available for reduction of Cr(VI) resulting in the mixed-phase precipitates. The results from the spectroscopic analysis support the hypothesis that Fe(II)-mediated Cr reduction prevails over direct enzymatic or organic based reduction in this system.

Varadharajan, C.; Nico, P. S.; Yang, L.; Marcus, M. A.; Steefel, C.; Larsen, J. T.; Beller, H. R.; Brodie, E. L.

2010-12-01

35

Spectroscopic Chemical Analysis Methods and Apparatus  

NASA Technical Reports Server (NTRS)

This invention relates to non-contact spectroscopic methods and apparatus for performing chemical analysis and the ideal wavelengths and sources needed for this analysis. It employs deep ultraviolet (200- to 300-nm spectral range) electron-beam-pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor lightemitting devices, and hollow cathode metal ion lasers. Three achieved goals for this innovation are to reduce the size (under 20 L), reduce the weight [under 100 lb (.45 kg)], and reduce the power consumption (under 100 W). This method can be used in microscope or macroscope to provide measurement of Raman and/or native fluorescence emission spectra either by point-by-point measurement, or by global imaging of emissions within specific ultraviolet spectral bands. In other embodiments, the method can be used in analytical instruments such as capillary electrophoresis, capillary electro-chromatography, high-performance liquid chromatography, flow cytometry, and related instruments for detection and identification of unknown analytes using a combination of native fluorescence and/or Raman spectroscopic methods. This design provides an electron-beampumped semiconductor radiation-producing method, or source, that can emit at a wavelength (or wavelengths) below 300 nm, e.g. in the deep ultraviolet between about 200 and 300 nm, and more preferably less than 260 nm. In some variations, the method is to produce incoherent radiation, while in other implementations it produces laser radiation. In some variations, this object is achieved by using an AlGaN emission medium, while in other implementations a diamond emission medium may be used. This instrument irradiates a sample with deep UV radiation, and then uses an improved filter for separating wavelengths to be detected. This provides a multi-stage analysis of the sample. To avoid the difficulties related to producing deep UV semiconductor sources, a pumping approach has been developed that uses ballistic electron beam injection directly into the active region of a wide bandgap semiconductor material.

Hug, William F.; Reid, Ray D.

2012-01-01

36

Spectroscopic studies of the transplutonium elements  

SciTech Connect

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.

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

1983-01-01

37

Spectroscopic study of Mentha oils  

NASA Astrophysics Data System (ADS)

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.

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

38

Neutron spectroscopic study of crystal  

SciTech Connect

We present time-of- ight inelastic neutron scattering measurements at low temperature on powder samples of the magnetic pyrochlore oxides Tb2Ti2O7 and Tb2Sn2O7. These two materials possess related, but dierent ground states, with Tb2Sn2O7 displaying \\soft" spin ice order below TN 0:87 K, while Tb2Ti2O7 enters a hybrid, glassy-spin ice state below Tg 0:2 K. Our neutron measurements, performed at T = 1:5 K and 30 K, probe the crystal eld states associated with the J = 6 states of Tb3+ within the appropriate Fd3m pyrochlore environment. These crystal eld states determine the size and anisotropy of the Tb3+ magnetic moment in each material's ground state, information that is an essential starting point for any description of the low temperature phase behavior and spin dynamics in Tb2Ti2O7 and Tb2Sn2O7. While these two materials have much in common, the cubic stanate lattice is expanded compared to the cubic titanate lattice. As our measurements show, this translates into a factor of 2 increase in the crystal eld bandwidth of the 2J +1 = 13 states in Tb2Ti2O7 compared with Tb2Sn2O7. Our results are consistent with previous measurements on crystal eld states in Tb2Sn2O7, wherein the ground state doublet corresponds primarily to mJ = j5i and the rst excited state doublet to mJ = j4i. In contrast, our results on Tb2Ti2O7 dier markedly from earlier studies, showing that the ground state doublet corresponds to a signicant mixture of mJ = j5i, mJ = j4i and mJ = j2i, while the rst excited state doublet corresponds to a mixture of mJ = j4i, mJ = j5i and mJ = j1i. We discuss these results in the context of proposed mechanisms for the failure of Tb2Ti2O7 to develop conventional long range order down to 50 mK.

Zhang, J. [McMaster University] [McMaster University; Fritsch, Katharina [McMaster University] [McMaster University; Hao, Z. [University of Waterloo, Canada] [University of Waterloo, Canada; Bagheri, B. V. [University of Waterloo, Canada] [University of Waterloo, Canada; Gingras, M.P.J. [University of Waterloo, Canada] [University of Waterloo, Canada; Granroth, Garrett E [ORNL] [ORNL; Jiramongkolchai, P. [Princeton University] [Princeton University; Cava, R. J. [Princeton University] [Princeton University; Schiffer, P [Pennsylvania State University] [Pennsylvania State University; Gaulin, Bruce D. [McMaster University] [McMaster University

2014-01-01

39

Structural and spectroscopic studies on calcium succinate single crystals  

NASA Astrophysics Data System (ADS)

Calcium succinate crystals have been grown by gel aided solution growth technique. The structure of the crystal is solved by single crystal XRD analysis. The Crystal structure of the title compound is triclinic having space group P(1) Powder XRD studies confirmed the good crystalline nature of the sample. The different functional groups and their assigned vibrations are discussed by FT-IR and FT Raman spectroscopic studies.

Binitha, M. P.; Pradyumnan, P. P.

2014-04-01

40

Spectroscope  

NSDL National Science Digital Library

In this activity, learners construct their own spectroscope as they explore and observe spectra from familiar light sources. Learners can be challenged to make technological improvements to their spectroscopes and/or participate in extension activities that expand their understanding of different kinds of spectra and sharpen their observing skills.

Observatory, Mcdonald

2008-01-01

41

Molecular structure investigation and spectroscopic studies on 2,3-difluorophenylboronic acid: a combined experimental and theoretical analysis.  

PubMed

This work presents the characterization of 2,3-difluorophenylboronic acid (abbreviated as 2,3-DFPBA, C(6)H(3)B(OH)(2)F(2)) by quantum chemical calculations and spectral techniques. The spectroscopic properties were investigated by FT-IR, FT-Raman UV-Vis, (1)H and (13)C nuclear magnetic resonance (NMR) techniques. The FT-IR spectrum (4000-400 cm(-1)) and the FT-Raman spectrum (3500-10 cm(-1)) in the solid phase were recorded for 2,3-DFPBA. The (1)H and (13)C NMR spectra were recorded in DMSO solution. The UV-Vis absorption spectra of the 2,3-DFPBA that dissolved in water and ethanol were recorded in the range of 200-400 nm. There are four possible conformers for this molecule. The computational results diagnose the most stable conformer of the 2,3-DFPBA as the trans-cis form. The structural and spectroscopic data of the molecule were obtained for all four conformers from DFT (B3LYP) with 6-311++G (d,p) basis set calculations. The theoretical wavenumbers were scaled and compared with experimental FT-IR and FT-Raman spectra. The complete assignments were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method, interpreted in terms of fundamental modes. We obtained good consistency between experimental and theoretical spectra. (13)C and (1)H NMR chemical shifts of the molecule were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. Finally the calculation results were analyzed to simulate infrared, Raman, NMR and UV spectra of the 2,3-DFPBA which show good agreement with observed spectra. PMID:22902933

Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Ali Cipiloglu, M; Kurt, Mustafa

2012-11-01

42

Vibrational spectroscopic study of fluticasone propionate  

NASA Astrophysics Data System (ADS)

Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.

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

2009-03-01

43

Spectroscopic studies of glycinium oxalate under pressure  

NASA Astrophysics Data System (ADS)

We report the first high pressure study on Glycinium oxalate complex up to 6 GPa. High pressure infrared and Raman spectroscopic measurements have been carried out in the spectral range 600 - 3600 cm-1. Most of the skeletal and internal vibrational modes lying in the complex 600 - 1200 cm-1 region have been reassigned and their high pressure behavior has been discussed. The spectra indicate subtle pressure induced transformations at 0.7 GPa and 2.5 GPa, with significant changes in the hydrogen bonding network.

Bhatt, Himal; Murli, C.; Garg, N.; Mishra, A. K.; Deo, M. N.; Sharma, Surinder M.

2014-04-01

44

Spectroscope  

NSDL National Science Digital Library

In this activity (posted on March 12, 2011), learners follow the steps to construct a spectroscope, a tool used to analyze light and color. First, learners use relatively simple materials to construct the device. Then, learners look through their spectroscopes at a variety of different light sources including incandescents, LEDs, compact fluorescents, sun light, etc. and compare what they observe. This resource includes a few examples of how certain chemicals form different colors of light.

Center, Oakland D.

2011-01-01

45

Apparatus and method for spectroscopic analysis of scattering media  

DOEpatents

Apparatus and method for spectroscopic analysis of scattering media. Subtle differences in materials have been found to be detectable from plots of intensity as a function of wavelength of collected emitted and scattered light versus wavelength of excitation light.

Strobl, Karlheinz (Los Angeles, CA) [Los Angeles, CA; Bigio, Irving J. (Los Alamos, NM) [Los Alamos, NM; Loree, Thomas R. (Santa Fe, NM) [Santa Fe, NM

1994-01-01

46

Vibrational spectroscopic and DFT study of trimethoprim  

NASA Astrophysics Data System (ADS)

Structural investigations by different vibrational spectroscopic methods: FTIR, FT-Raman and surface-enhanced Raman scattering (SERS) spectroscopy, as well as density functional theory (DFT) calculations were performed on trimethoprim (5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine). A reliable assignment of vibrational IR, Raman and SERS bands was possible by a proper choice of model used in quantum chemical calculations. Based on SERS spectrum analysis it is shown that the molecule is adsorbed on the silver surface through the pyrimidine ring, in a perpendicular orientation. Two theoretical models were used in order to simulate the silver surface and the interaction with trimethoprim molecule, the accuracy of the models being evaluated by comparing the predicted bands position of the two complexes with the SERS result.

Ungurean, Alia; Leopold, Nicolae; David, Leontin; Chi?, Vasile

2013-02-01

47

Spectroscopic analysis of the superluminous HD327083  

NASA Astrophysics Data System (ADS)

New optical high-resolution (R»50 000) spectra of the star HD 327083 are reported in this work. The Balmer and Fe ii lines show P Cygni profiles, while He i lines are all in pure absorption, ressembling the spectra of the Luminous Blue Variable HR Carinae. However, the blue absorption components of the Balmer lines are more pronounced in HD 327083 than in HR Carinae, indicating a more intense mass loss. We performed a spectroscopic analysis of the Balmer lines (Ha, Hb, Hg and Hd) with a non-LTE code to analyse extended atmospheres. The basic assumptions are: spherical symmetry, stationary and homogeneity. The density structure r(r) is related to the mass loss rate and the velocity field via the equation of continuity. The velocity field is pre-specified in an ad-hoc way as a b-type law. The statistical equilibrium equations are solved using the escape probability method for calculating the source function while the transfer equation is solved using the "SEI" - Sobolev Exact Integration - method. Due the large number of "free" parameters we constructed a primary grid of models (theoretical profiles) based on the results provided by theoretical evolutionary paths. In other words, the input parameters L«, T«, and AHe are those provided as output data of the evolutive models. We chose the tracks of the Geneve group since they are available in the WEB in the range of initial masses from Mi = 25 M¤ to 120 M¤. The derived stellar parameters for HD 327083 are: log(L«/L¤) = 6.0, T« = 11500 K, = 8.0´10-5 M¤/yr and He/H = 0.2 (by number). From these results and considering the similarity with HR Carinae we concluded that HD 327083 is a superluminous object in an evolved phase of an evolutive track of MZAMS~ 60 M¤. It might be a B[e] Supergiant but it is most likely to be about to enter in a typical LBV phase.

Machado, M. A. D.; de Araujo, F. X.

2003-08-01

48

Spectroscopic analysis of insulating crystal fibers  

NASA Technical Reports Server (NTRS)

A new technique is described for investigating the optical properties of solid-state laser materials using single-crystal fibers grown by a laser-heated pedestal-growth technique. Single-crystal fiber samples can be prepared more rapidly and less expensively than crystals grown by more conventional methods; however, they are smaller and less uniform, making spectroscopic measurements difficult. A simple procedure for extracting the optical absorption and emission spectra of insulating crystal fibers is demonstrated with a titanium-doped sapphire fiber sample; results are comparable to those from Czochralski-grown material.

Buoncristiani, A. M.; Byvik, C. E.; Albin, S.

1988-01-01

49

The Origin, Composition and History of Comets from Spectroscopic Studies  

NASA Technical Reports Server (NTRS)

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.

Allamandola, L. J.

1997-01-01

50

Spectroscopic analysis of protein Fe-NO complexes.  

PubMed

The toxic free radical NO (nitric oxide) has diverse biological roles in eukaryotes and bacteria, being involved in signalling, vasodilation, blood clotting and immunity, and as an intermediate in microbial denitrification. The predominant biological mechanism of detecting NO is through the formation of iron nitrosyl complexes, although this is a deleterious process for other iron-containing enzymes. We have previously applied techniques such as UV-visible and EPR spectroscopy to the analysis of protein Fe-NO complex formation in order to study how NO controls the activity of the bacterial transcriptional regulators NorR and NsrR. These studies have analysed NO-dependent biological activity both in vitro and in vivo using diverse biochemical, molecular and spectroscopic methods. Recently, we have applied ultrafast 2D-IR (two-dimensional IR) spectroscopy to the analysis of NO-protein interactions using Mb (myoglobin) and Cc (cytochrome c) as model haem proteins. The ultrafast fluctuations of Cc and Mb show marked differences, indicating altered flexibility of the haem pockets. We have extended this analysis to bacterial catalase enzymes that are known to play a role in the nitrosative stress response by detoxifying peroxynitrite. The first 2D-IR analysis of haem nitrosylation and perspectives for the future are discussed. PMID:21936804

Bellota-Antón, César; Munnoch, John; Robb, Kirsty; Adamczyk, Katrin; Candelaresi, Marco; Parker, Anthony W; Dixon, Ray; Hutchings, Matthew I; Hunt, Neil T; Tucker, Nicholas P

2011-10-01

51

Comprehensive processing, display and analysis forin vivo MR spectroscopic imaging  

Microsoft Academic Search

Image reconstruction for magnetic resonance spectroscopic imaging (MRSI) requires specialized spatial and spectral data processing methods and benefits from the use of several sources of prior information that are not commonly available, including MRI-derived tissue segmentation, morphological analysis and spectral characteristics of the observed metabolites. In addition, incorporating information obtained from MRI data can enhance the display of low-resolution metabolite

A. A. Maudsley; A. Darkazanli; J. R. Alger; L. O. Hall; N. Schuff; C. Studholme; Y. Yu; A. Ebel; A. Frew; D. Goldgof; Y. Gu; R. Pagare; F. Rousseau; K. Sivasankaran; B. J. Soher; P. Weber; K. Young; X. Zhu

2006-01-01

52

Land degradation studies using spectroscopic techniques  

NASA Astrophysics Data System (ADS)

Desertification is a land degradation problem of major importance in the arid regions of the world. Deterioration in soil and plant cover have adversely affected nearly 70 percent of the drylands as mainly the result of human mismanagement of cultivated and range lands. Overgrazing, woodcutting, cultivation practices inducing accelerated water and wind erosion, improper water management leading to salinisation, are all causes of land degradation. In addition to vegetation deterioration, erosion, and salinisation, desertification effects can be seen in loss of soil fertility, soil compaction, and soil crusting. Combating desertification involves having an accurate knowledge on a current land degradation status and the magnitude of the potential hazard. Quantitative, high-spectral resolution remote sensing (imaging spectroscopy) can dramatically increase the accuracy of dryland monitoring. In this context, a new research project has been implemented, aiming at using the capabilities of imaging spectroscopy in order to (a) monitor land degradation processes, (b) assess land degradation status, and (c) gain indicators for characterising specific surface properties related to water cycles, erosion processes and plant productivity in drylands. In particular, hyperspectral data, coupled with field/laboratory spectroscopy and laboratory analyses, can be used to derive more quantitative and specific soil properties directly linked to soil degradation status, such as soil chemical properties, organic matter, mineralogical content, infiltration capacity, aggregation capacity, and runoff coefficient. However, further studies are needed, toward a better understanding of the desertification processes, and more detailed analyses of the spectroscopic features associated with land degradation processes. Several test sites representing different environmental conditions are being established. This presentation will focus on a test site in the Brandenburg region, a dry area in north-Eastern Germany, where open pit mine overburden dumps left from the coal-mining era in the former East Germany, not recultivated, have become "dunes" where nothing grows. Our project in this small catchment area is to explore the relationships between spectral reflectance and rainfall runoff modelling.

Chabrillat, S.; Kaufmann, H.; Merz, B.; Hill, J.; Mueller, A.

2003-04-01

53

Spectroscopic Studies of Cryogenic Fluids: Benzene in Argon and Helium.  

National Technical Information Service (NTIS)

Optical spectroscopic studies of aromatic solute molecules in simple cryogenic solvents have been successfully used to investigate microscopic properties of different solute/solvent systems. Structure, interaction potentials, solubility, and dynamics of l...

R. Nowak E. R. Bernstein

1987-01-01

54

Study of physical properties of spectroscopic binary stars  

NASA Astrophysics Data System (ADS)

The main results of a study of a catalogue of physical parameters of 1041 spectroscopic binaries are presented. The results of the analysis of the observed distributions of SB's over the main, genetically and evolutionary stipulated parameters, such as apparent brightness and orbital periods, are given. The main effects of observational selection that prevent the direct analysis of innate distributions of SB's over masses, mass ratios of components, and the large semiaxes of their orbits are briefly discussed. Models of observed distributions of bright SB's over M(1), M(2)/M(1) and the large semiaxes are computed by a program which, starting with arbitrary distributions, generates models of observed distributions, taking into account the important effects of observational selection and stellar evolution.

Popova, E. I.; Tutukov, A. V.; Yungelson, L. R.

1982-11-01

55

Analysis of Urinary Calculi Using Infrared Spectroscopic Imaging  

NASA Astrophysics Data System (ADS)

Kidney stone disease is a cosmopolitan disease, occurring in both industrialized and developing countries and mainly affecting adults aged 2060 years. The formation of kidney stones is a process that includes many factors. Its primary and contributing pathogenic factors are genetic, nutritional and environmental, but also include personal habits. Information about the chemical structure of kidney stones is of great importance to the treatment of the kidney diseases. The usefulness of such information was first recognized in early 1950s. Analysis of urinary stones by various chemical methods, polarization microscopy, x-ray diffraction, porosity determination, solid phase NMR, and thermo analytical procedures have been widely used. Unfortunately, no one method is sufficient to provide all the clinically useful information about the structure and composition of the stones. Infrared spectroscopy can be considered a relatively new method of kidney stone analysis. It allows to identify any organic or inorganic molecules the constituents of kidney stones. So far this method had never been used to collect information about kidney stone component patterns in Lithuania. Since no epidemiological studies have been performed in this field, the medical treatment of kidney stone disease is empirical and often ineffective in hospitals around the country. The aim of this paper is to present some results of analysis of kidney stones extracted from local patients using FTIR spectroscopical microscopy.

Sablinskas, Valdas; Lesciute, Daiva; Hendrixson, Vaiva

2009-06-01

56

Spectroscopic study of demineralization and restoration processes in dental enamel  

NASA Astrophysics Data System (ADS)

The spectroscopic study of dental enamel by LIBS (laser induced breakdown spectroscopy), FTIR (Fourier transform infrared) and XRD (X-ray diffraction) are represented. The changes of enamel structure and composition in process of natural (caries) and artificial demineralization and restoration were studied. In comparison of sound and carious enamel LIBS showed a decrease of the content of Ca, P and change of the content of some other macro-and trace elements (Mn, Na, Fe, Zn etc). The character of the elemental composition variation was stipulated by the concrete disease. Analysis of FTIR and XRD spectra of dental samples, subjected to artificial demineralization and restoration, showed that restoration action reveals slower, than demineralization. And in some cases the damage of crystals after restoration is more significant than after demineralization.

Sokolova, Tatiana N.; Surmenko, Elena L.; Tuchin, Valery V.; Kishen, A.; Chebotarevsky, Yu. V.

2007-07-01

57

Spectroscopic studies on the photochemical decarboxylation mechanisms of synthetic pyrethroids.  

PubMed

A novel radical trapping technique combined with a fluorescence spectroscopic analysis has been employed to investigate the radical intermediates produced by photodecarboxylation of four synthetic pyrethroids: fenvalerate (SMD), fenpropathrin (DTL), cyphenothrin (GKL), and cypermethrin (AGT). Under photoirradiation at >290 nm, all pyrethroids underwent direct photolysis via homolytic cleavage of the carbon-oxygen bonds in the ester groups. The consumed amount of a nitroxide free radical, as a trapping agent for the intermediate radical of a pyrethroid, was determined by ESR, which was the measure of the reaction yield of a photochemically generated ?-cyano-3-phenoxybenzyl radical common to all pyrethroids. The reactivities of the pyrethroids studied was in the sequence of SMD > DTL > GKL > AGT. Furthermore, nanosecond transient absorption spectroscopy demonstrated that geminate recombination of the radical pair within a solvent cage is the main deactivation route of the photochemically generated ?-cyano-3-phenoxybenzyl radical common for all pyrethroids studied. PMID:22936363

Suzuki, Yusuke; Ishizaka, Shoji; Kitamura, Noboru

2012-12-01

58

Note: Multivariate system spectroscopic model using Lorentz oscillators and partial least squares regression analysis  

NASA Astrophysics Data System (ADS)

Multivariate system spectroscopic model plays important role in understanding chemometrics of ensemble under study. Here in this manuscript we discuss various approaches of modeling of spectroscopic system and demonstrate how Lorentz oscillator can be used to model any general spectroscopic system. Chemometric studies require customized templates design for the corresponding variants participating in ensemble, which generates the characteristic matrix of the ensemble under study. The typical biological system that resembles human blood tissue consisting of five major constituents i.e., alanine, urea, lactate, glucose, ascorbate; has been tested on the model. The model was validated using three approaches, namely, root mean square error (RMSE) analysis in the range of +/-5% confidence interval, clerk gird error plot, and RMSE versus percent noise level study. Also the model was tested across various template sizes (consisting of samples ranging from 10 up to 1000) to ascertain the validity of partial least squares regression. The model has potential in understanding the chemometrics of proteomics pathways.

Gad, R. S.; Parab, J. S.; Naik, G. M.

2010-11-01

59

A detailed spectroscopic study of an Italian fresco  

NASA Astrophysics Data System (ADS)

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.

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

2005-02-01

60

Fs spectroscopic studies of the plant photoreceptor phytochrome  

NASA Astrophysics Data System (ADS)

Femtosecond time-resolved spectroscopic studies were performed with the plant photoreceptor phytochrome in its biologically active form, Pfr. After excitation of Pfr with 150 fs pulses at 730 nm the changes in the optical density (OD(t) were measured at selected probe wavelengths. Following excitation, bleaching of the two ground-state absorption bands, the Q band at 730 nm and the Soret band at 402 nm were observed. Moreover, a transient absorption at around 800 nm was detected. Analysis of the experimental data strongly suggests that excited Pfr* decays with 700뀬 fs in part to the ground state and in part to another state, which absorbs at 760 nm and decays with a time constant of 4.5ǂ.5 ps. These two decays are the fastest light-induced processes observed in the deexcitation of Pfr so far.

Rentsch, S.; Bischoff, M.; Hermann, G.; Strehlow, D.

1998-02-01

61

A detailed spectroscopic study of an Italian fresco  

SciTech Connect

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.

Barilaro, Donatella; Crupi, Vincenza; Majolino, Domenico; Barone, Germana; Ponterio, Rosina [Dipartimento di Fisica and Instituto Nazionale per la Fisica della Materia (INFM), Universita di Messina, Contrada Papardo, Salita Sperone 31, P.O. Box 55, 98166 Messina (Italy); Dipartimento di Scienze dalla Terra, Universita di Messina, Contrada Papardo, Salita Sperone 31, P.O. Box 55, 98166 Messina (Italy); Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (CNR-IPCF), Sezione di Messina, Via La Farina 237, 98123 Messina (Italy)

2005-02-15

62

Spectroscopic Analysis of Rock Mineral-Garnet of South Kerala  

Microsoft Academic Search

Spectroscopic techniques serve an important tool in the characteization of minerals. Garnet samples taken from the rocks of Vattapara, Kovalam, Mukkunnimala have been used. Spectral analysis of purified and dried garnet is carried out using FT-IR, FT-Raman, X-ray diffraction, X-ray Fluorescence techniques. Different d spacing values obtained from the XRD pattern fairly matches standard d spacing values of almandine. It

S. Vidya; S. L. Varun; T. Vijayakumar; I. Hubert Joe; V. S. Jayakumar

2008-01-01

63

Spectroscopic and Electrochemical Analysis of Psychotropic Drugs  

PubMed Central

Psychotropic drugs are an important family of compounds from a medical point of view. Their application in therapy requires methods for the determination in pharmaceutical dosage forms and body fluids. Several methods for their analysis have been reported in the literature. Among the methods, spectrophotometric and electrochemical are very useful for the determination of the drugs. Some of the spectrophotometric methods are based on the formation of the binary and ternary compounds with complexes of metals. The formed compounds are sparingly soluble in water, but quantitatively extracted from aqueous phase into organic solvents and the extracts are intensely colored and stable for a few days. These complexes have been employed in pharmaceutical analysis. The electrochemical procedures are very useful in determination of the psychotropic substances in pharmaceutical preparations.

Puzanowska-Tarasiewicz, H.; Misiuk, W.; Mielech-Lukasiewicz, K.; Kuzmicka, L.

2009-01-01

64

Gradualism: A Method for Primary Instruction on Spectroscopic Analysis in Introductory Organic Chemistry  

Microsoft Academic Search

The pedagogical style of gradualism is described for the instruction of spectroscopic analysis in the introductory organic chemistry laboratory. Gradualism is defined as a series of steps or lessons that build one upon the other until the student is able to solve complex problems. Each step is briefly described as part of a pre-laboratory study assignment with follow-up application by

Christopher W. Alexander; Gary L. Asleson; Charles F. Beam; Marion T. Doig; Frederick J. Heldrich; Shannon Studer-Martinez

1999-01-01

65

Synthesis, spectroscopic characterization, X-ray powder structure analysis, DFT study and in vitro anticancer activity of N-(2-methoxyphenyl)-3-methoxysalicylaldimine  

NASA Astrophysics Data System (ADS)

Schiff base, N-(2-methoxyphenyl)-3-methoxysalicylaldimine (MPMS), was synthesized and characterized by spectroscopic methods. Crystal structure of the title compound crystallizing in the orthorhombic space group P ca2 1, a = 23.695(2), b = 7.7011(8), c = 7.3570(9) Å, V = 1342.5(2) Å 3, Z = 4 has been solved from X-ray powder diffraction data following direct-space approach and refined by the Rietveld method. In solid state, the salicylaldimine compound exists as a phenol-imine tautomer with a strong intramolecular O-H…N hydrogen bond. The molecular geometry and electronic structure of MPMS were calculated at the DFT level using the hybrid exchange-correlation functional, BLYP. The optimized molecular geometry corresponds to the non-planar conformation of the molecule as established by the crystallographic analysis. The anticancer activity of the title Schiff base was evaluated against three different cell lines, SF-268, MCF-7 and NCI-H460.

Chattopadhyay, Basab; Basu, Soumya; Chakraborty, Paramita; Choudhuri, Soumitra Kumar; Mukherjee, Alok K.; Mukherjee, Monika

2009-08-01

66

Spectroscopic analysis of automotive engine oil  

NASA Astrophysics Data System (ADS)

Infrared absorption spectroscopy (IR) and acousto-optic tunable filter (AOTF) technology were combined to develop a portable spectrophotometer for use in engine oil analysis to identify and quantify oil contaminants and residue products, Preliminary measurements were taken with a field-portable AOTF-based spectrometer (2 to 4.5 micrometers ) and an FTIR spectrometer (2 to 25 micrometers ) for comparison. Absorption spectra of used and unused oil samples were measured and compared to determine absorption changes between the various samples resulting from oil degradation and any chemical reactions that might have taken place during high- temperature engine lubrication. These preliminary results indicate that IR spectroscopy can be used for oil quality monitoring in automotive engines, which will help predict and prevent engine failure and degradation. This work can be extended to other remote sensing applications, such as the monitoring of environmental oil spills.

Dahmani, Rachid; Gupta, Neelam

2002-02-01

67

Parallel multithread computing for spectroscopic analysis in optical coherence tomography  

NASA Astrophysics Data System (ADS)

Spectroscopic Optical Coherence Tomography (SOCT) is an extension of Optical Coherence Tomography (OCT). It allows gathering spectroscopic information from individual scattering points inside the sample. It is based on time-frequency analysis of interferometric signals. Such analysis requires calculating hundreds of Fourier transforms while performing a single A-scan. Additionally, further processing of acquired spectroscopic information is needed. This significantly increases the time of required computations. During last years, application of graphical processing units (GPU's) was proposed to reduce computation time in OCT by using parallel computing algorithms. GPU technology can be also used to speed-up signal processing in SOCT. However, parallel algorithms used in classical OCT need to be revised because of different character of analyzed data. The classical OCT requires processing of long, independent interferometric signals for obtaining subsequent A-scans. The difference with SOCT is that it requires processing of multiple, shorter signals, which differ only in a small part of samples. We have developed new algorithms for parallel signal processing for usage in SOCT, implemented with NVIDIA CUDA (Compute Unified Device Architecture). We present details of the algorithms and performance tests for analyzing data from in-house SD-OCT system. We also give a brief discussion about usefulness of developed algorithm. Presented algorithms might be useful for researchers working on OCT, as they allow to reduce computation time and are step toward real-time signal processing of SOCT data.

Trojanowski, Michal; Kraszewski, Maciej; Strakowski, Marcin; Pluci?ski, Jerzy

2014-05-01

68

Spectroscopic Studies of Double Beta Decays and MOON  

SciTech Connect

This is a brief review of future spectroscopic experiments of neutrino-less double beta decays (0{nu}{beta}{beta}) and the MOON (Mo Observatory Of Neutrinos) project. Spectroscopic 0{nu}{beta}{beta} 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 0{nu}{beta}{beta} studies with the {nu}-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 {beta}{beta} source film.

Ejiri, H. [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan); Nuclear Science, Czech Technical University, Brehova, Prague, Czech Republic, National Institute of Radiological Sciences, Chiba, 263-8555 (Japan)

2007-10-12

69

Nonlinear spectroscopic studies of chiral media  

SciTech Connect

Molecular chirality plays an important role in chemistry, biology, and medicine. Traditional optical techniques for probing chirality, such as circular dichroism and Raman optical activity rely on electric-dipole forbidden transitions. As a result, their intrinsic low sensitivity limits their use to probe bulk chirality rather than chiral surfaces, monolayers or thin films often important for chemical or biological systems. Contrary to the traditional chirality probes, chiral signal in sum-frequency generation (SFG) is electric-dipole allowed both on chiral surface and in chiral bulk making it a much more promising tool for probing molecular chirality. SFG from a chiral medium was first proposed in 1965, but had never been experimentally confirmed until this thesis work was performed. This thesis describes a set of experiments successfully demonstrating that chiral SFG responses from chiral monolayers and liquids are observable. It shows that, with tunable inputs, SFG can be used as a sensitive spectroscopic tool to probe chirality in both electronic and vibrational resonances of chiral molecules. The monolayer sensitivity is feasible in both cases. It also discusses the relevant theoretical models explaining the origin and the strength of the chiral signal in vibrational and electronic SFG spectroscopies.

Belkin, Mikhail Alexandrovich

2004-05-20

70

A spectroscopic study of the mineral paceite (calcium acetate)  

Microsoft Academic Search

A comprehensive spectroscopic analysis consisting of Raman, infrared (IR) and near-infrared (NIR) spectroscopy was undertaken on two forms of calcium acetate with differing degrees of hydration. Monohydrate (Ca(CH3COO)2·H2O) and half-hydrate (Ca(CH3COO)2·0.5H2O) species were analysed. Assignments of vibrational bands due to the acetate anion have been made in all three forms of spectroscopy. Thermal analysis of the mineral was undertaken to

Anthony W. Musumeci; Ray L. Frost; Eric R. Waclawik

2007-01-01

71

Spectroscopic study of demineralization and restoration processes in dental enamel  

Microsoft Academic Search

The spectroscopic study of dental enamel by LIBS (laser induced breakdown spectroscopy), FTIR (Fourier transform infrared) and XRD (X-ray diffraction) are represented. The changes of enamel structure and composition in process of natural (caries) and artificial demineralization and restoration were studied. In comparison of sound and carious enamel LIBS showed a decrease of the content of Ca, P and change

Tatiana N. Sokolova; Elena L. Surmenko; Valery V. Tuchin; A. Kishen; Yu. V. Chebotarevsky

2007-01-01

72

Spectroscopic study of low-lying {sup 16}N levels  

SciTech Connect

The magnitude of the {sup 15}N(n,{gamma}){sup 16}N reaction rate in asymptotic giant branch stars depends directly on the neutron spectroscopic factors of low-lying {sup 16}N levels. A new study of the {sup 15}N(d,p){sup 16}N reaction is reported populating the ground and first three excited states in {sup 16}N. The measured spectroscopic factors are near unity as expected from shell model calculations, resolving a long-standing discrepancy with earlier measurements that had never been confirmed or understood. Updated {sup 15}N(n,{gamma}){sup 16}N reaction rates are presented.

Bardayan, D. W.; Nesaraja, C. D.; Pain, S. D.; Smith, M. S. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); O'Malley, P. D.; Cizewski, J. A.; Hatarik, R.; Peters, W. A. [Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903 (United States); Blackmon, J. C. [Deptartment of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Chae, K. Y.; Jones, K. L.; Moazen, B. H.; Paulauskas, S.; Pittman, S. T.; Schmitt, K. T. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Chipps, K. A. [Department of Physics, Colorado School of Mines, Golden, Colorado 80401 (United States); Kozub, R. L.; Shriner, J. F. Jr. [Physics Department, Tennessee Technological University, Cookeville, Tennessee 38505 (United States); Matei, C. [Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830 (United States)

2008-11-15

73

Spectroscopic analysis of ferrite doped with different rare earth elements  

Microsoft Academic Search

The IR spectroscopic analysis for the ferrite of the general formula Mg1+xTixRyFe2?2x?yO4, where 0?x?0.9; 0?y?0.5; R=La, Nd and Gd, was carried out in order to identify the formation of spinel structure. The bands at ?585 and ?442cm?1 confirm the presence of Fe3+ ions on both tetrahedral and octahedral sites, respectively. The high frequency bands of the spinels should be assigned

M. A Ahmed; E Ateia; S. I El-Dek

2002-01-01

74

Ultrafast spectroscopic studies of metal nanoparticles  

NASA Astrophysics Data System (ADS)

An important aim of nanoparticle research is to understand how the properties of materials depend on their size and shape. In this thesis, time-resolved spectroscopy has been used to measure the physical properties of nanometer sized objects, such as the characteristic time scale for heat dissipation and their elastic moduli. In our experiments, metal nanoparticles are excited with a sub-picosecond laser pulse, which causes a rapid increase in the lattice temperature. In the first project, the rate of heat dissipation from Au nanoparticles to their surroundings was examined for different size gold nanospheres in aqueous solution. Laser induced lattice heating can also impulsively excite the phonon modes of the particle that correlate with the expansion co-ordinates. For spherical Au particles the symmetric breathing mode is excited. Experimental results for ˜50 nm diameter Au particles were compared to a model calculation where the expansion coordinate is treated as a damped harmonic oscillator. This gives information about the excitation mechanism. In the second project, the extensional and breathing modes of cylindrical gold nanorods were studied by time-resolved spectroscopy. These experiments yield values for the elastic constants for the rods. Both the extensional mode and the breathing mode results show that gold nanorods produced by wet chemical techniques have a smaller elastic moduli than bulk gold. HR-TEM and SAED studies show that the rods have a 5-fold twinned structure with growth along the [110] crystal direction. However, neither the growth direction nor the twinning provide a simple explanation for the reduced elastic moduli measured in the experiments. In a final project, polydisperse silver nanoparticle samples were investigated. A signal due to coherently excited vibrational motion was observed. The analysis shows that the observed signal arises from the triangular-shaped particles, rather than the rods or spheres that are present in the sample. The triangles dominate the response because they have a much narrower size distribution than the rods.

Hu, Min

75

Infrared Imaging, Spectroscopic, and Photometric Studies of Comets.  

National Technical Information Service (NTIS)

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/Hall...

R. D. Gehrz

1997-01-01

76

Spectroscopic Studies of Semiconductor Structures in Magnetic Fields  

NASA Astrophysics Data System (ADS)

The aptitude of magneto-spectroscopic methods for studying the electronic and spin properties of semiconductor structures is demonstrated with a few examples of our recent work on two-dimensional electron gases and semiconductor quantum dots, on bulk GaAs and GaN, as well as on thin graphitic layers.

Potemski, Marek

77

Spectroscopic studies on binding of shikonin to human serum albumin  

Microsoft Academic Search

The binding properties on shikonin to human serum albumin (HSA) have been studied for the first time using fluorescence spectroscopy in combination with UV-visible absorbance spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy. The results of spectroscopic measurements suggested that the hydrophobic interaction is the predominant intermolecular force stabilizing the complex, which is in good agreement with

Wenying He; Ying Li; Jianniao Tian; Huanxiang Liu; Zhide Hu; Xingguo Chen

2005-01-01

78

Hydrogen bonds in α-oxalic acid dihydrate-A Raman spectroscopic study  

NASA Astrophysics Data System (ADS)

We have carried out Raman spectroscopic studies on ?-oxalic acid dihydrate up to ˜15 GPa. Our data analysis indicates the occurrence of a phase transition across 2.2 GPa. The softening of O-H stretching mode, associated with water molecule, implies the strengthening of the O-H---O hydrogen bond and possible formation of hydronium ion.

Mishra, A. K.; Murli, Chitra; Bhatt, H.; Sharma, Surinder M.

2014-04-01

79

Spectroscopic analysis technique for arc-welding process control  

NASA Astrophysics Data System (ADS)

The spectroscopic analysis of the light emitted by thermal plasmas has found many applications, from chemical analysis to monitoring and control of industrial processes. Particularly, it has been demonstrated that the analysis of the thermal plasma generated during arc or laser welding can supply information about the process and, thus, about the quality of the weld. In some critical applications (e.g. the aerospace sector), an early, real-time detection of defects in the weld seam (oxidation, porosity, lack of penetration, ...) is highly desirable as it can reduce expensive non-destructive testing (NDT). Among others techniques, full spectroscopic analysis of the plasma emission is known to offer rich information about the process itself, but it is also very demanding in terms of real-time implementations. In this paper, we proposed a technique for the analysis of the plasma emission spectrum that is able to detect, in real-time, changes in the process parameters that could lead to the formation of defects in the weld seam. It is based on the estimation of the electronic temperature of the plasma through the analysis of the emission peaks from multiple atomic species. Unlike traditional techniques, which usually involve peak fitting to Voigt functions using the Levenberg-Marquardt recursive method, we employ the LPO (Linear Phase Operator) sub-pixel algorithm to accurately estimate the central wavelength of the peaks (allowing an automatic identification of each atomic species) and cubic-spline interpolation of the noisy data to obtain the intensity and width of the peaks. Experimental tests on TIG-welding using fiber-optic capture of light and a low-cost CCD-based spectrometer, show that some typical defects can be easily detected and identified with this technique, whose typical processing time for multiple peak analysis is less than 20msec. running in a conventional PC.

Mirapeix, Jesús; Cobo, Adolfo; Conde, Olga; Quintela, María Ángeles; López-Higuera, José-Miguel

2005-09-01

80

Fundamental spectroscopic studies of carbenes and hydrocarbon radicals  

SciTech Connect

This document details activities during this reporting period topics discussed are: The first spectroscopic identification of the HCCCO and DCCCO radicals; detection of new vibrationally excited states of the carbon chain radicals CCH and CCD and the three-membered carbene ring, cyclopropenylidene; determination of an accurate structure of the cumulene carbene H{sub 2}CCC; analysis the hyperfine structure in the SiC radical; and the undertaking of a systematic search for new sulfur bearing radicals.

Thaddeus, P.; Gottlieb, C.

1992-05-01

81

Halo Nucleus Be11: A Spectroscopic Study via Neutron Transfer  

NASA Astrophysics Data System (ADS)

The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct-reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus Be11, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the Be10(d,?p) reaction has been used in inverse kinematics at four beam energies to study the structure of Be11. The spectroscopic factors extracted using the adiabatic model were found to be consistent across the four measurements and were largely insensitive to the optical potential used. The extracted spectroscopic factor for a neutron in an n?j=2s1/2 state coupled to the ground state of Be10 is 0.71(5). For the first excited state at 0.32 MeV, a spectroscopic factor of 0.62(4) is found for the halo neutron in a 1p1/2 state.

Schmitt, K. T.; Jones, K. L.; Bey, A.; Ahn, S. H.; Bardayan, D. W.; Blackmon, J. C.; Brown, S. M.; Chae, K. Y.; Chipps, K. A.; Cizewski, J. A.; Hahn, K. I.; Kolata, J. J.; Kozub, R. L.; Liang, J. F.; Matei, C.; Matoš, M.; Matyas, D.; Moazen, B.; Nesaraja, C.; Nunes, F. M.; O'Malley, P. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Roberts, A.; Shapira, D.; Shriner, J. F., Jr.; Smith, M. S.; Spassova, I.; Stracener, D. W.; Villano, A. N.; Wilson, G. L.

2012-05-01

82

Raman spectroscopic studies of disordered ferroelectric oxides  

NASA Astrophysics Data System (ADS)

Relaxational properties of compositionally disordered AB03 perovskite oxides were studied. These oxides are the prototypical soft ferroelectric (FE) mode systems, and their interesting dipolar relaxational properties are determined by their long, strongly temperature-dependent correlation lengths for the dipolar interactions. The simple cases involve dilute chemical substitutions in the incipient ferroelectrics KTaO3 and SrTiO3, which exhibit relatively weak, low-temperature Debye-type relaxations. More complicated dipolar interactions are seen in B-site disordered Nb-doped KTaO3, which exhibits glass-like relaxor and relaxor-to-ferroelectric crossover behaviors at low temperatures. Finally, there is a class of more complex perovskites represented by PMN, PZN-PT and the PLT that exhibit strong, high-temperature relaxor and/or ferroelectric properties. The renewed interest in the KTa1-xNbxO (KTN) mixed perovskite materials, especially in high quality thin films, is connected with their remarkable dielectric properties in the dilute compositions. Off-center Nb ions in the highly polarizable KTaO3 lattice provide a drastic increase in the dielectric peak, up to 20 times in comparison with the pure KTaO3 and KNbO3. The effects of the substrate and the symmetry-breaking defects on their vibration spectra were studied by micro-Raman spectroscopy. An anomalous residual intensity of the forbidden first-order scattering modes in the cubic paraelectric phase of the KTN films was connected with the formation of polar microregions even far above the bulk Tc. On the whole, the KTN film behavior shows the existence of specific defects enhancing the perovskite unit cell in the film so that the activity of off-center Nb ions increases in producing larger electric dipoles and extending the precursor phase above Tc. In diluted compositions with low Nb concentrations KTN materials exhibit formation of polar nano regions and relaxor like behavior. This behavior is analogous with behavior of well know relaxor systems, such as PbMg1/3Nb2/3O3 (PMN) and Pb1-x LaxTiO3 (PLT). Raman scattering was studied in model relaxor ferroelectrics PbSc 1/2Ta1/2O3 (PST) and PMN and in related low-permittivity materials SrAl1/2Ta1/2O3 (SAT), SrAl 1/2Nb1/2O3 (SAN) and BaMg1/3Ta 2/3O3 (BMT). Comparative analysis of the Raman spectra gives evidence that complex perovskites of this type consist of nanoscale clusters with the 1:1 B-site order, irrelevant to whether a stoichiometric composition for the B cations is 1:1 or 1:2. This result is in agreement with the recent microstructure studies of both PST and PMN by direct methods. The low-permittivity compounds reveal the static basic spectrum for the corresponding 1:1 or 1:2 compositions. The basic spectrum is modified in relaxors by dynamic effects in the course of evolution to the ferroelectric state. Model relaxors PST and PMN show clearly such dynamic effects as mode broadening and a central peak. In A-site substituted complex perovskite PLT systems micro-Raman results indicate that the crystal structure of the PLT films was strongly influenced by the La contents. The dielectric properties of PLT thin films were studied in the temperature range 80--700 K and results indicate that PLT thin films undergo normal-to-relaxor ferroelectric transformation with 30 at% La content in PLT films. The observed behavior is evaluated in terms of diffuseness and Vogel-Fulcher relationship, which is typical for relaxor ferroelectrics. It is consistent with typical relaxor behavior of disordered materials with polar nanoregions.

Savvinov, Alexey A.

83

Renaissance patinas in Ubeda (Spain): mineralogic, petrographic and spectroscopic study.  

PubMed

Different analytical techniques were used for microstructural and compositional analysis of the ochre-coloured patinas that appear on the calcarenite substrate of monuments in the historical settings of Ubeda and Baeza (Spain). Optical microscopy, scanning electron microscopy-energy dispersive x-ray spectrometry (SEM-EDX), x-ray diffraction, Raman spectroscopy and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) were employed and a critical comparison of their experimental requirements, strengths and weaknesses is presented. The study focussed on two churches in Ubeda where patinas were widespread in ornamental elements. These films contained calcite as the principal component, and traces of dolomite and feldspars. Clear identification of calcium oxalate, mainly in the form of whewellite, was achieved by infrared and Raman spectroscopic studies. Results from texture, distribution and composition of the patinas in ornamental elements suggest that ancient treatments were applied for protection of Renaissance façades and consolidation of weathered older façades. The patinas were seldom found on supporting elements. Their different composition, apatite was found together with oxalates, and location may suggest a biogenic origin here. Gypsum crusts were sometimes found over the patinas. PMID:18483811

Campos-Suñol, M J; Domínguez-Vidal, A; Ayora-Cañada, M J; De la Torre-López, M J

2008-06-01

84

Spectroscopic study of coal structure and reactivity  

SciTech Connect

The aim of this project is to perform quantitative analysis of the Fourier transform infrared (FT-IR) spectra of coals and coal extracts. The major difficulty encountered in the analysis of the FT-IR spectra of coals is the complexity of the bands, which consist of many closely overlapped peaks. Two techniques that are commonly used for the quantitative analysis of complex FT-IR spectra are deconvolution and curve-fitting. Deconvolution is a mathematical technique that narrows the speaks in a spectrum, thereby improving the effective resolution. Curve-fitting optimizes a set of ban parameters, using a least squares criterion, to simulate the true spectrum. We have recently completed work on optimizing the combination of these two techniques with the aim of applying this to the spectra of coals and coal extracts. Two types of deconvolution were investigated in this context: Fourier self-deconvolution (FSD) and maximum likelihood restoration (MLR). It was concluded that for noisy spectra MLR gave superior results. 3 refs., 7 figs.

Rabenstein, D.L.

1990-09-07

85

Spectroscopic studies of some antidiabetic drugs  

NASA Astrophysics Data System (ADS)

The infrared absorption spectrum of antidiabetic drugs Pioglitazone and Pioglitazone·HCl has been recorded at high resolution in the spectral region 200-4000 cm -1. Most of the frequencies in the latter compound are slightly lower in magnitude than corresponding value in the former. The absorption intensities are however slightly larger. In order to confirm the vibrational assignment of the bands obtained from experimental observation, a normal co-ordinate analysis has been carried out using semi empirical AM1 method through MOPAC 5.1 computer program. In addition to these compounds, the vibrational frequencies for some of the intermediate metabolite of Pioglitazone have also been calculated.

Rai, Amareshwar K.; Rai, D. K.

2003-06-01

86

Infrared spectroscopic study of halloysite-potassium acetate intercalation complex  

NASA Astrophysics Data System (ADS)

Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been used to study the molecular structure of halloysite and potassium acetate intercalated halloysite and to determine the structural changes of halloysite through intercalation. The MIR spectra show all fundamental vibrations including the hydroxyl units, basic aluminosilicate framework and water molecules in the structure of halloysite and its intercalation complex. Comparison between halloysite and halloysite-potassium acetate intercalation complex shows almost all bands observed for halloysite are also observed for halloysite-potassium acetate intercalation complex apart from bands observed in the 1700-1300 cm -1 region, but with differences in band intensity. However, NIR spectra, based on MIR spectra, provide sufficient evidence to analyze the structural changes of halloysite through intercalation. There are obvious differences between halloysite and halloysite-potassium acetate intercalation complex in all spectral ranges. Therefore, the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for molecular structural analysis.

Cheng, Hongfei; Liu, Qinfu; Yang, Jing; Zhang, Jinshan; Frost, Ray L.; Du, Xiaoman

2011-03-01

87

Spectroscopic study of TMOS–TMSM–MMA gels  

Microsoft Academic Search

A 3-(trimethoxy-silyl)propyl methacrylate (TMSM)–methylmethacrylate (MMA)–tetramethyl-orthosilicate (TMOS) hybrid glass, has been prepared using a sol–gel process. In order to study the influence of each of the inorganic matrices, the gels obtained from TMOS and TMSM have been studied separately, the hybrid compound, they have been investigated using Raman spectroscopic, FT-IR and NMR techniques. The networks formed in both TMOS and TMSM

Z. Sassi; J. C. Bureau; A. Bakkali

2002-01-01

88

Spectroscopic ellipsometry data analysis: Measured vs. calculated quantities  

SciTech Connect

Spectroscopic ellipsometry is a very powerful technique for optical characterization of thin-film and bulk materials, but the technique measures functions of complex reflection coefficients, which are usually not of interest per se. The interesting characteristics such as film thickness, surface roughness thickness, and optical functions can be determined only by modeling the near-surface region of the sample. However, the measured quantities are not equivalent to those determined from the modeling. Ellipsometry measurements determine elements of the sample Mueller matrix, but the usual result of modeling calculations are elements of the sample. Often this difference is academic, but if the sample depolarizes the light, it is not. Ellipsometry calculations also include methods for determining the optical functions of materials. Data for bulk materials are usually accurate for substrates, but are not appropriate for most thin films. Therefore, reasonable parameterizations are quite useful in performing spectroscopic ellipsometry data analysis. Recently, there has been an increased interest in anisotropic materials, both in thin-film and bulk form. A generalized procedure will be presented for calculating the elements of the Jones matrix for any number of layers, any one of which may or may not be uniaxial.

Jellison, G.E. Jr.

1997-05-01

89

Spectroscopic study of bituminous oxidative stress  

NASA Astrophysics Data System (ADS)

Bitumen, as each organic substance, is a product which alters over time. Indeed, roads deteriorate under the effect of several phenomena. A number of studies have been undertaken to increase the quality of road's coating, mostly by adding polymer to bitumen. This work was based on the study, by electron paramagnetic resonance (EPR), FTIR and Synchronous UV fluorescence, of different base and modified bitumens after different treatments used to simulate the ageing (gamma irradiation, thermal treatment). Our purpose was to compare and correlate the results obtained by different techniques to improve the knowledge of bitumen's reactivity and evolution submitted to ageing phenomena.

Masmoudi, H.; Rebufa, C.; Raffi, J.; Permanyer, A.; Kister, J.

2004-05-01

90

Spectroscopic Study of Microwave Induced Plasma  

SciTech Connect

The results of the spatial distribution studies of electron densities, excitation and rotational temperatures and atomic line intensities of various elements in an atmospheric pressure mini-MIP torch with tangential argon flow. The electron number density, ne, is determined from the width of the hydrogen H{beta} 486.13 nm line while excitation temperature, Texc, is evaluated from the Boltzmann plot of relative line intensities either of carrier gas-argon or neutral iron that is introduced in the form of aerosols in MIP, The rotational temperatures, Trot, are determined from the relative intensities of OH (R2 and Q1 branch) electronic band A2{sigma} - X2{pi} (0,0) and to N{sub 2}{sup +} first negative system B{sup 2} {sigma}{sub u}{sup +} - X{sup 2} {sigma}{sub g}{sup +} (P branch). For the selected input power of 100 W, the influence of hydrogen in the wet and desolvated aerosols and support gas and the corresponding changes of the electron density, excitation and rotational temperature distributions are studied. The influence of potassium, low ionization potential element, to the spatial distribution of ne, Texc and Trot is studied also. Spatial intensity distributions and maximum intensities for investigate atomic line are determinate for the same conditions.

Jovicevic, S. [Institute of Physics, 11081 Belgrade P.O. Box 68 (Serbia and Montenegro)

2004-12-01

91

Evaluation of Salt Influence on Sugar Consumption by Suspension Cells Based on Spectroscopic Analysis  

PubMed Central

The influence of metal salt on sugar consumption by suspension cells in food models constructed by a sugar and salt aqueous solution was investigated based on mid-infrared spectroscopic analysis. The contaminated suspension cells in the food model could be detected using the spectral feature change that measured the present spectrum subtracted in the initial spectrum. The cells were prepared for growth and although the cell did not grow under the induction period, the cell activation (start of sugar metabolism) was detected on the subtracted spectral behavior before the cell growth. The rough grasp of the spectral change behavior is useful for the high-throughput spectroscopic method to detect the contaminated cell activation. Furthermore, the detailed sugar consumption kinetics of the cells was also investigated based on the spectroscopic method. The kind of added salt in the food model influenced the cell activation and the potassium ions play an important role in the plant cells. The living cells activity in fresh food may act to prevent microbial contamination and to suppress the growth of the contaminated microorganism. Both the simple and detailed analyses based on the spectroscopic method presented in this study might be useful for risk management of food.

Kameoka, Takaharu; Hashimoto, Atsushi

2013-01-01

92

Spectroscopic study of 6 galaxies (Brough+, 2007)  

NASA Astrophysics Data System (ADS)

The BGG and BCG galaxy samples were selected from the Group Evolution Multi-wavelength Study (GEMS; Osmond & Ponman, 2004MNRAS.350.1511O; Forbes et al., 2006PASA...23...38F) and the BCG sample presented in Brough et al. (2005MNRAS.364.1354B). In both these samples the galaxy is selected as the brightest galaxy closest to the X-ray centroid, that is, closest to the centre of the potential well of these structures. (5 data files).

Brough, S.; Proctor, R.; Forbes, D. A.; Couch, W. J.; Collins, C. A.; Burke, D. J.; Mann, R. G.

2008-07-01

93

Spectroscopic study of coal structure and reactivity  

SciTech Connect

Work done during this period (December 15, 1989 to March 14, 1990) covered two of the three primary areas of study of this project. The first involved the continuing development a of step-scanning interferometer for the photoacoustic depth-profiling of materials whose composition varies in the spatial region between 5 and 50 {mu}m from its surface. The second covered the initial construction of an on-line interface between a supercritical fluid chromatograph (SFC) and a Fourier transform infrared (FT-IR) spectrometer for monitoring the composition of coal extracts. 5 refs., 8 figs.

Rabenstein, D.L.

1990-09-07

94

Spectroscopic Analysis of Cool Galactic R CrB Star Candidates  

NASA Astrophysics Data System (ADS)

The results of optical spectra analysis of two carbon-rich long-period variables V1983 Cyg and V2047 Cyg are presented. The stars were suspected to be cool R CrB variables candidates according to the photometric light curves. We compared the spectroscopic properties of the selected stars with those of DY Per and ordinary carbon stars to check their possible connection to cool RCBs. Also the spectral synthesis technique was used for analysis of the obtained high-resolution spectra, dominated by strong absorption features of carbon-bearing molecules. Our spectroscopic study suggests that both stars are more similar to ordinary N-type carbon stars than to DY Per star. For V1983 Cyg star possible absorption in Balmer lines is detected.

Smirnova, O.; Zavcs, L.; Pavlenko, Y. V.; Kaminsky, B.

2011-05-01

95

Spectroscopic studies on well-diagnosed pinch columns  

SciTech Connect

We report on laser light scattering diagnostics and spectroscopic studies of plasmas of a gas-liner z-pinch where Thomson scattering is performed radially resolved while the resolution of spectroscopy is along the z-axis. The gas-liner pinch is used for accurate measurements of line shapes of multiply ionized atoms and can be operated in a stable and an unstable condition. Implications for the line profiles measured are discussed.

Wrubel, Th.; Buescher, S.; Kunze, H.-J. [Institute for Experimental Physics, Ruhr-University-Bochum, 44780 Bochum (Germany); Ahmad, I. [Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan)

1998-09-28

96

Spectroscopic Study of Radiation Effects in DMAAS:Cr Ferroelectrics  

Microsoft Academic Search

This paper presents the results of investigations of the radiation effects in NH2(CH3)2Al(SO4)2·6H2O crystals doped with chromium. On the basis of the spectroscopic study it has been shown that comparatively low doses of radiation first of all cause a recharging of Cr on Cr ions. Besides, the processes of dehydrogenation and the changes in arrangement of the hydrogen bond network

V. Kapustianyk; V. Rudyk; Yu. Korchak; A. Batiuk; B. Kulyk; Z. Czapla

2005-01-01

97

Nonlinear spectroscopic studies of interfacial molecular ordering  

SciTech Connect

The second order nonlinear optical processes of second harmonic generation and sum frequency generation are powerful new probes of surfaces. They possess unusual surface sensitivity due to the symmetry properties of the nonlinear susceptibility. In particular, infrared-visible sum frequency generation (SFG) can obtain the vibrational spectrum of sub-monolayer coverages of molecules. In this thesis, we explore the unique information that can be obtained from SFG. We take advantage of the sensitivity of SFG to the conformation of alkane chains to study the interaction between adsorbed liquid crystal molecules and surfactant treated surfaces. The sign of the SFG susceptibility depends on the sign of the molecular polarizability and the orientation, up or down, of the molecule. We experimentally determine the sign of the susceptibility and use it to determine the absolute orientation to obtain the sign of the molecular polarizability and show that this quantity contains important information about the dynamics of molecular charge distributions. Finally, we study the vibrational spectra and the molecular orientation at the pure liquid/vapor interface of methanol and water and present the most detailed evidence yet obtained for the structure of the pure water surface. 32 refs., 4 figs., 2 tabs.

Superfine, R.

1991-07-01

98

Progress report on nuclear spectroscopic studies  

SciTech Connect

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.

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

1996-01-16

99

Spectroscopic studies of silver boro tellurite glasses  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

100

First spectroscopic study of {sup 22}Si  

SciTech Connect

In an experiment at the LISE3 facility of GANIL, we produced the proton-rich isotope {sup 22}Si by the fragmentation of a {sup 36}Ar primary beam at 95 MeV/nucleon. After implantation in a detector telescope, we studied the decay of {sup 22}Si via a measurement of charged particles emitted during the decay. The most important {beta}-delayed proton activity is observed at an energy of {ital E}{sub {ital p}} = (1.99{plus_minus}0.05) MeV with a branching ratio of (20{plus_minus}2){percent}. The spectra allow us also to determine the half-life of {sup 22}Si to be {ital T}{sub 1/2} = (29{plus_minus}2) ms. These results are compared with theoretical estimates and model predictions. {copyright} {ital 1996 The American Physical Society.}

Blank, B.; Andriamonje, S.; Boue, F.; Czajkowski, S.; Del Moral, R.; Dufour, J.P.; Fleury, A.; Pourre, P.; Pravikoff, M.S. [Centre d`Etudes Nucleaires de Bordeaux-Gradignan, F-33175 Gradignan Cedex (France)] [Centre d`Etudes Nucleaires de Bordeaux-Gradignan, F-33175 Gradignan Cedex (France); Schmidt, K. [Gesellschaft fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany)] [Gesellschaft fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany); Hanelt, E. [Inst. fuer Kernphysik, TH Darmstadt, SchloSgartenstrasse 9, D-64289 Darmstadt (Germany)] [Inst. fuer Kernphysik, TH Darmstadt, SchloSgartenstrasse 9, D-64289 Darmstadt (Germany); Orr, N.A. [LPC-ISMRA, Boulevard du Marechal Juin, F-14050 Caen Cedex (France)] [LPC-ISMRA, Boulevard du Marechal Juin, F-14050 Caen Cedex (France)

1996-08-01

101

Spectroscopic studies near the proton drip line  

SciTech Connect

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.

Toth, K.S. (Oak Ridge National Lab., TN (USA)); Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A. (Lawrence Berkeley Lab., CA (USA)); Robertson, J.D. (Kentucky Univ., Lexington, KY (USA))

1990-01-01

102

Spectroscopic and quantum chemical studies on bromopyrazone.  

PubMed

In this study, the FT-IR, micro-Raman and UV-vis. spectra of bromopyrazone molecule, C10H8BrN3O, (with synonym,1-phenyl-4-amino-5-bromopyridazon-(6) or 5-amino-4-bromo-2-phenyl-3(2H)-pyridazinone) were recorded experimentally. The molecular structure, vibrational wavenumbers, electronic transition absorption wavelengths in ethanol solvent, HOMOs and LUMOs analyses, molecular electrostatic potential (MEP), natural bond orbitals (NBO), nonlinear optical (NLO) properties and atomic charges of bromopyrazone molecule have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. The obtained results show that the calculated vibrational frequencies and UV-vis. values are in a good agreement with experimental data. PMID:24996217

Gökce, Halil; Bahçeli, Semiha

2014-12-10

103

A Raman spectroscopic study of a fulgurite.  

PubMed

A Raman microspectroscopic study of several fulgurites has been undertaken. A fulgurite is an amorphous mineraloid, a superheated glassy solid that is formed when a lightning bolt hits a sandy or rocky ground and thermal energy is transferred. The Raman spectra revealed several forms of crystalline and fused silica and also the presence of polyaromatic hydrocarbons found in an interfacial zone of a glass bubble. This, together with the presence of anatase, a low-temperature polymorph of TiO(2), suggested that some regions of the fulgurite specimen were not subjected to temperatures of 1800 degrees C, which are attained when lightning hits the surface of sand or a rock. PMID:20529946

Carter, Elizabeth A; Hargreaves, Michael D; Kee, Terence P; Pasek, Matthew A; Edwards, Howell G M

2010-07-13

104

Spectroscopic studies of Np(V) complexation  

SciTech Connect

The complexation of Np(V) with aliphatic (oxalic, malonic, succinic, glutaric, and maleic) and aromatic (phthalic, pyromellitic, hemimellitic, trimellitic, and mellitic) polycarboxylic acids was studied by spectrophotometry at 1 M ionic strength (NaClO{sub 4}) and 23 C. For the aliphatic systems, the stability of the neptunyl complexes was found to decrease as the carbon chain length of the ligand increased which was attributed to an entropy effect. In polycarboxylate systems, the stability constant decreased in the order hemimellitate > mellitate > pyromellitate > trimellitate, phthalate. With the exception of hemimellitate, this trend follows the order of decreasing basicity of the ligand. After correction of the stability constant for statistical effects, the stability of the mellitate, pyromellitate, trimellitate, and phthalate complexes were approximately the same. The unexpected strength the hemimellitate complexation was attributed to an increase in electron density at the binding site from the non-chelating carboxylate group through induction. The complexation of phthalate, trimellitate and hemimellitate and mellitate were studied as a function of pH. Trimellitate and mellitate were found to form ML as well as ML complexes while for phthalate and hemimellitate only ML species were observed. The stability constants of the cation-cation complexes Np(V)-U(VI) and Np(V)-Np(V), measured at 6 M ionic strength (HClO{sub 4}) and 25 C, were found to be 2.45 {+-} 0.05 and 1.41 {+-} 0.14, respectively. The change in enthalpy for the Np(V)-U(VI) system as determined by the measurement of the stability constant as function of temperature was -14.3 {+-} 1.6 kJ/mol.

Stout, B.E.

1989-01-01

105

Spectroscopic studies of metalloporphyrins in micellar systems  

SciTech Connect

Micelles have been used as simple model systems to simulate the electrostatic and hydrophobic interactions found in biological membranes and in the haem cavity. The authors continue in the report on both the optical and transient excited state behavior of metalloporphyrins as probes of micellar environments. For NiPP (nickel protoporphyrin IX) they have compared porphyrin optical propertie such as the [alpha]/[beta] ratio, and the Gouterman A[sub 1g] parameter to those of Orange OT and the solvent probe E[sub T](30) in an attempt to gauge the influence of the micellar environment on porphyrin reactivity and conversely, the porphyrins effect on the aggregation behavior of the surfactant monomers and their formation of micelles. The results of optical and transient Raman experiments indicate that at low surfactant concentrations the porphyrin is primarily aggregated. Increases in the surfactant concentration up to the CMC caused continuous changes in the optical properties of the probe molecules. However, the relatively large changes in the value of E[sub T](30), which was used to probe the electrostatic properties of the micelle, are not reflected in the transient excited state vibrational behavior of NiPP. Studies on NiPP in various micellar systems, in which the porphyrin was monomeric, have lead to the conclusion that in anionic, cationic, nonionic, or reverse micelles the porphyrin resides mainly in the hydrophobic region of the micelle.

Wicks, B.; Findsen, E.W. (Univ. of Toledo, OH (United States))

1992-01-01

106

Spectroscopic and theoretical study of amlodipine besylate  

NASA Astrophysics Data System (ADS)

In this work, a joint experimental (FT-IR, FT-Raman, NMR) and theoretical DFT study on 3-ethyl-5-methyl-2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridinedicarboxylate benzenesulphonate (amlodipine besylate) compound is reported. The experimental vibrational spectra have been assigned based on DFT calculations performed at B3LYP level of theory using the standard 6-31G(d) basis set and a uniform scaling of the calculated wave numbers. The mean deviation in reproducing the whole Raman and FT-IR spectra by B3LYP/6-31G(d) calculations is 7.7 and 6.0 cm -1, respectively. The experimental 1H NMR spectrum of amlodipine besylate was successfully reproduced by theoretical DFT calculations of the nuclear magnetic shielding tensors, using the GIAO method. The molecular electrostatic potential of the molecule has been calculated and used for predicting site candidates for electrophilic attack.

Szabó, L.; Chi?, V.; Pîrn?u, A.; Leopold, N.; Cozar, O.; Orosz, Sz.

2009-04-01

107

Photoelectron spectroscopic studies of 5-halouracil anions  

SciTech Connect

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.

Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Bowen, Kit H. [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Sevilla, Michael D. [Department of Chemistry, Oakland University, Rochester, Michigan 48309 (United States); Rak, Janusz [Department of Chemistry, University of Gdansk, 80-952 Gdansk (Poland)

2011-01-07

108

Fluorescence spectroscopic studies of DNA dynamics  

SciTech Connect

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.

Scalettar, B.A.

1987-04-01

109

Quantitative comparison of analysis methods for spectroscopic optical coherence tomography  

PubMed Central

Spectroscopic optical coherence tomography (sOCT) enables the mapping of chromophore concentrations and image contrast enhancement in tissue. Acquisition of depth resolved spectra by sOCT requires analysis methods with optimal spectral/spatial resolution and spectral recovery. In this article, we quantitatively compare the available methods, i.e. the short time Fourier transform (STFT), wavelet transforms, the Wigner-Ville distribution and the dual window method through simulations in tissue-like media. We conclude that all methods suffer from the trade-off in spectral/spatial resolution, and that the STFT is the optimal method for the specific application of the localized quantification of hemoglobin concentration and oxygen saturation.

Bosschaart, Nienke; van Leeuwen, Ton G.; Aalders, Maurice C. G.; Faber, Dirk J.

2013-01-01

110

Spectroscopic study of porphyrin-caffeine interactions.  

PubMed

The association between water-soluble porphyrins: 4,4',4?,4'''-(21 H,23 H-porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H(2)TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21 H,23 H-porphine (H(2)TPPS(4)), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21 H,23 H-porphine tetra-p-tosylate (H(2)TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21 H,23 H-porphine tetra-p-tosylate (H(2)TMePyP), the Cu(II) complexes of H(2)TTMePP and H(2)TMePyP, as well as chlorophyll a with caffeine (1,3,7-trimethylxanthine) has been studied analysing their absorption and emission spectra in aqueous (or acetone in case of chlorophyll a) solution. During the titration by caffeine the porphyrins absorption spectra undergo the evolution - the bathochromic effect can be observed as well as the hypochromicity of the Soret maximum. The association constants were calculated using curve-fitting procedure (K(AC) of the order of magnitude of 10(3) mol(-1)). Whereas the emission spectra point at the presence of the fluorescence quenching effect testifying for the partial inactivation of the porphyrin molecule. The fluorescence quenching constants were calculated from Stern-Volmer plots. The results obtained show that caffeine can interact with water-soluble porphyrins and through formation of stacking complexes is able to quench their ability to emission. PMID:22763925

Makarska-Bialokoz, Magdalena

2012-11-01

111

A Photometric and Spectroscopic Study of Dwarf and Giant Galaxies in the Coma Cluster. I. Wide-Area Photometric Survey: Observation and Data Analysis  

NASA Astrophysics Data System (ADS)

We carried out a deep photometric and spectroscopic survey of wide areas in the Coma cluster, aiming to investigate the properties of galaxy population in different environments within the cluster. We present the results in a series of papers. This paper, the first of the series, describes the imaging observations and photometric data reduction. Imaging data were taken with the wide-field mosaic CCD camera, which was attached to the prime focus of the 4.2 m William Herschel Telescope at La Palma, Canary Islands. Our observations covered a large field of view (2.22 deg2) from the cluster center to the outskirts, and our photometry is complete to a limiting magnitude of R~=23 mag. The limit of secure star-galaxy discrimination is, however, brighter at R=20 mag. We identified 3147 galaxies down to this limit in the part (1.32 deg2) of the survey area, together with 662 galaxies identified in the control field SA 57. We measured surface photometric parameters and compiled a photometric catalog for these galaxies. Statistical properties of the catalog are shown in this paper, while the catalog itself is given in a forthcoming paper in the series. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Komiyama, Y.; Sekiguchi, M.; Kashikawa, N.; Yagi, M.; Doi, M.; Iye, M.; Okamura, S.; Shimasaku, K.; Yasuda, N.; Mobasher, B.; Carter, D.; Bridges, T. J.; Poggianti, B. M.

2002-02-01

112

Synthesis, spectroscopic characterization, thermal analysis and electrical conductivity studies of Mg(II), Ca(II), Sr(II) and Ba(II) vitamin B2 complexes  

NASA Astrophysics Data System (ADS)

Riboflavin (RF) complexes of Mg(II), Ca(II), Sr(II) and Ba(II) were successfully synthesized. Structures of metal complexes obtained were confirmed and characterized by elemental analysis, molar conductance, and infrared spectra. DC electrical conductivity measurements indicated that the alkaline earth metal (II) complexes of RF ligand are non-electrolytes. Elemental analysis of chelates suggest that the metal(II) ligand ratio is 1:2 with structure formula as [M(RF) 2( X) 2]· nH 2O. Infrared assignments clearly show that RF ligand coordinated as a bidentate feature through azomethine nitrogen of pyrazine ring and C dbnd O of pyrimidine-2,4-dione. Thermal analyses of Mg(II), Ca(II), Sr(II) and Ba(II) complexes were investigated using (TG/DSC) under atmospheric nitrogen between 30 and 800 °C. The surface morphology of the complexes was studied by SEM. The electrical conductivities of RF and its metal complexes were also measured with DC electrical conductivity in the temperature range from room to 483 K.

Refat, Moamen S.; Moussa, Mohamed A. A.; Mohamed, Soha F.

2011-05-01

113

Preparation, characterization, spectroscopic (FT-IR, FT-Raman, UV and visible) studies, optical properties and Kubo gap analysis of In2O3 thin films  

NASA Astrophysics Data System (ADS)

Indium oxide (In2O3) thin films are successfully deposited on microscopic glass substrate at different temperatures by spray pyrolysis technique using Indium acetate as precursor solution. The physical properties of these films are characterized by XRD, SEM, AFM, UV-visible, PL and Photo acoustic measurements. XRD analysis revealed that the films are polycrystalline in nature having cubic crystal structure with a preferred grain orientation along (2 2 2) plane. The average transmittance in the visible region is found to vary from 60% to 93% depending upon the substrate temperature. The complete vibrational analysis has been carried out and the optimized parameters are calculated using HF and DFT (LSDA, B3LYP and B3PW91) methods with 3-21G(d,p) basis set for In2O3. The fundamental frequencies are calculated and assigned according to the experimental frequencies. Furthermore, 13C NMR and 1H NMR chemical shifts are calculated by using the gauge independent atomic orbital (GIAO) technique with HF/B3LYP/B3PW91 methods on same basis set. A study of the electronic properties; absorption wavelengths, excitation energy, dipole moment, Kubo gap (HOMO and LUMO) and frontier molecular orbital energies, are performed by HF and DFT methods. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) is executed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the compound are calculated in gas phase.

Jothibas, M.; Manoharan, C.; Ramalingam, S.; Dhanapandian, S.; Johnson Jeyakumar, S.; Bououdina, M.

2013-10-01

114

Continuous spectroscopic analysis of vanadous and vanadic ions  

SciTech Connect

Spectroscopic methods were investigated for the determination of vanadium ions in aqueous solutions arising in the production of vanadium (11) formate and its use in the LOMI (Low Oxidation-state Metal Ion) process for the chemical decontamination of systems in nuclear power plants. In the LOMI process, a dilute solution of vanadous formate and picolinic acid is used. The vanadous formate n reduces metal oxides in the scale on the equipment, causing the scale to break up and become suspended. The picolinic acid chelates these materials and makes them soluble. During the decontamination the progress is followed by analyses of the metal ions and of the radioactivity. When the values stop increasing, the decontamination is terminated. At present, it cannot be determined if the values are no longer changing due to all the scale being removed or due to the vanadous ion being spent. Infrared and ultraviolet-visible analysis were investigated as the means of analyzing for vanadium species. It was found that the complex formed by V(II) with picolinic acid could be used for colorimetric analysis for V(II) in the range of 0 {minus} 0.011 moles/liter, which encompasses the concentration range used in the LOMI process. The findings will be used to develop an on-line instrument for continuously monitoring V(II) during decontamination.

Bishop, J.V.; Dutcher, R.A.; Fisher, M.S.; Kottle, S.; Stowe, R.A. [Omni Tech International Ltd., Midland, MI (United States)

1993-10-01

115

FTIR spectroscopic studies of lipid dynamics in phytosphingosine ceramide models of the stratum corneum lipid matrix  

Microsoft Academic Search

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 d35-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

Mark E. Rerek; Dina Van Wyck; Richard Mendelsohn; David J. Moore

2005-01-01

116

A spectroscopic study of the mineral paceite (calcium acetate).  

PubMed

A comprehensive spectroscopic analysis consisting of Raman, infrared (IR) and near-infrared (NIR) spectroscopy was undertaken on two forms of calcium acetate with differing degrees of hydration. Monohydrate (Ca(CH(3)COO)(2).H(2)O) and half-hydrate (Ca(CH(3)COO)(2).0.5H(2)O) species were analysed. Assignments of vibrational bands due to the acetate anion have been made in all three forms of spectroscopy. Thermal analysis of the mineral was undertaken to follow its decomposition under a nitrogen atmosphere. Three major mass loss steps at approximately 120, 400 and 600 degrees C were revealed. These mass losses correspond very well to firstly, the loss of co-ordinated water molecules, and then the loss of water from the acetate anion, followed by finally the loss of carbon dioxide from the carbonate mineral to form a stable calcium oxide. PMID:17070100

Musumeci, Anthony W; Frost, Ray L; Waclawik, Eric R

2007-07-01

117

A spectroscopic study of the mineral paceite (calcium acetate)  

NASA Astrophysics Data System (ADS)

A comprehensive spectroscopic analysis consisting of Raman, infrared (IR) and near-infrared (NIR) spectroscopy was undertaken on two forms of calcium acetate with differing degrees of hydration. Monohydrate (Ca(CH 3COO) 2·H 2O) and half-hydrate (Ca(CH 3COO) 2·0.5H 2O) species were analysed. Assignments of vibrational bands due to the acetate anion have been made in all three forms of spectroscopy. Thermal analysis of the mineral was undertaken to follow its decomposition under a nitrogen atmosphere. Three major mass loss steps at ˜120, 400 and 600 °C were revealed. These mass losses correspond very well to firstly, the loss of co-ordinated water molecules, and then the loss of water from the acetate anion, followed by finally the loss of carbon dioxide from the carbonate mineral to form a stable calcium oxide.

Musumeci, Anthony W.; Frost, Ray L.; Waclawik, Eric R.

2007-07-01

118

Infrared spectroscopic studies of GdBaCoO  

NASA Astrophysics Data System (ADS)

This paper reports infrared spectroscopic studies on GdBaCo 2O 5.5 layered perovskite which exhibits successive magnetic transitions from paramagnetic to ferromagnetic to antiferromagnetic states as well as high-temperature metal to insulator transition and a change in charge transport mechanism at low temperature. Infrared absorption spectra recorded at various temperatures in the range 80-350 K reveal changes in the positions of Co-O stretching and bending frequencies which provide an explanation to the magnetic and transport behaviour of this compound.

Ganorkar, Shraddha; Priolkar, K. R.

2010-11-01

119

Spectroscopic studies of cathode materials for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

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 previous claims based only on electrochemical data and ex situ XRD and IR measurements that the oxidation of Co(OH)2 leads to the formation of an inert CoOOH phase impervious to further reduction.

Totir, Dana Alexa

2000-10-01

120

Quantum mechanical, spectroscopic studies (FT-IR, FT-Raman, NMR, UV) and normal coordinates analysis on 3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide.  

PubMed

Famotidine (3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide) is a histamine H2-receptor antagonist that inhibits stomach acid production, and it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). Quantum chemical calculations of the equilibrium geometry of famotidine in the ground state were carried out using density functional theory (DFT/B3LYP) with the 6-311G(d,p) basis set. In addition, harmonic vibrational frequencies, infrared intensities and Raman activities were calculated at the same level of theory. A detailed interpretation of the infrared and Raman spectrum of the drug is also reported. Theoretical simulations of the FT-IR, and FT-Raman spectra of the title compound have been calculated. Good correlations between the experimental (1)H and (13)C NMR chemical shifts and calculated GIAO shielding tensors were found. The results of the energy and oscillator strength calculations by time-dependent density functional theory (TD-DFT) supplement the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The linear polarizability and first order hyperpolarizabilities of the studied molecule indicate that the compound is a good candidate for nonlinear optical materials. PMID:23507526

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

2013-05-01

121

X-ray spectroscopic studies of secondary battery materials  

NASA Astrophysics Data System (ADS)

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, due to a highly reversible chemical change. Formation of Mn+4 at the expense of Mn+3, upon charging is an unexpected result. Mn+7 does not appear to be created in this process.

Kostov, Svilen Dimitar

1998-09-01

122

Photometric and Spectroscopic Analysis for the Determination of Physical Parameters of an Eclipsing Binary Star System  

NASA Astrophysics Data System (ADS)

A binary star system is a pair of stars that are bound together by gravity. Most of the stars that we see in the night sky are members of multiple star systems. A system of stars where one star passes in front of the other (as observed from Earth) on a periodic basis is called an eclipsing binary. Eclipsing binaries can have very short rotational periods and in all cases these pairs of stars are so far away that they can only be resolved from Earth as a single point of light. The interaction of the two stars serves to produce physical phenomena that can be observed and used to study stellar properties. By careful data collection and analysis is it possible for an amateur astronomer using commercial, low cost equipment (including a home built spectroscope) to gather photometric (brightness versus time) and spectroscopic (brightness versus wavelength) data, analyze the data, and calculate the physical properties of a binary star system? Using a CCD camera, tracking mount and telescope photometric data of BB Pegasi was collected and a light curve produced. 57 Cygni was also studied using a spectroscope, tracking mount and telescope to prove that Doppler shift of Hydrogen Balmer absorption lines can be used to determine radial velocity. The orbital period, orbital velocity, radius of each star, separation of the two stars and mass of each star was calculated for the eclipsing binary BB Pegasi using photometric and spectroscopic data and Kepler’s 3rd Law. These data were then compared to published data. By careful use of consumer grade astronomical equipment it is possible for an amateur astronomer to determine an array of physical parameters of a distant binary star system from a suburban setting.

Reid, Piper

2013-01-01

123

Spectroscopic study and evaluation of red-absorbing fluorescent dyes.  

PubMed

The spectroscopic characteristics (absorption, emission, and fluorescence lifetime) of 13 commercially available red-absorbing fluorescent dyes were studied under a variety of conditions. The dyes included in this study are Alexa647, ATTO655, ATTO680, Bodipy630/650, Cy5, Cy5.5, DiD, DY-630, DY-635, DY-640, DY-650, DY-655, and EVOblue30. The thorough characterization of this class of dyes will facilitate selection of the appropriate red-absorbing fluorescent labels for applications in fluorescence assays. The influences of polarity, viscosity, and the addition of detergent (Tween20) on the spectroscopic properties were investigated, and fluorescence correlation spectroscopy (FCS) was utilized to assess the photophysical properties of the dyes under high excitation conditions. The dyes can be classified into groups based on the results presented. For example, while the fluorescence quantum yield of ATTO655, ATTO680, and EVOblue30 is primarily controlled by the polarity of the surrounding medium, more hydrophobic and structurally flexible dyes of the DY-family are strongly influenced by the viscosity of the medium and the addition of detergents. Covalent binding of the dyes to biotin and subsequent addition of streptavidin results in reversible fluorescence quenching or changes in the relaxation time of other photophysical processes of some dyes, most likely due to interactions with tryptophan residues in the streptavin binding site. PMID:12526709

Buschmann, Volker; Weston, Kenneth D; Sauer, Markus

2003-01-01

124

Ultraviolet spectroscopic studies of Seyfert 1 galaxies and quasars  

NASA Astrophysics Data System (ADS)

I have undertaken UV spectroscopic studies of Seyfert 1 and quasars using UV spectral data obtained by IUE satellite. The IUE satellite has obtained UV spectroscopic data of AGNs in the 1100-3100 A wavelength range. I have studied the spectra of about 80 strong Seyfert 1 galaxies and quasars observed from 1971-1990 by IUE satellite. I have found some interesting emission line and continuum correlations in these objects. They show a strong line and continuum luminosity correlations in the 1100-3100 AA wavelength region. Similar correlations have been observed in the X-rays and optical region in these objects. Two broad classes of flax variabilities over a time-scale of 3-4 days have also been found in this wavelength region. The equivalent widths of strong emission lines exhibits Baldwin effect. No characteristic variability period in line and continuum flux has been observed. The over all similarity in spectral properties observed in Seyfert 1 galaxies and quasars suggests that similar physical esses my be undergoing at the centers of these objects. The impact these and some more results obtained by me will be discussed in detail during the meeting.

Doddamani, Vijayakumar H.

125

Spectroscopic study of Er:Sm doped barium fluorotellurite glass.  

PubMed

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. PMID:20510646

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

2010-09-15

126

A Planetary Environment and Analysis Chamber Equipped with Multiple Spectroscopic Sensors  

NASA Astrophysics Data System (ADS)

A Planetary Environment and Analysis Chamber (PEACH) has been developed at Washington University in St. Louis, in order to conduct co-registered spectroscopic measurements on geological samples under planetary relevant environmental conditions.

Sobron, P.; Wang, A.

2010-03-01

127

A Planetary Environment and Analysis Chamber Equipped with Multiple Spectroscopic Sensors  

Microsoft Academic Search

A Planetary Environment and Analysis Chamber (PEACH) has been developed at Washington University in St. Louis, in order to conduct co-registered spectroscopic measurements on geological samples under planetary relevant environmental conditions.

P. Sobron; A. Wang

2010-01-01

128

Detection and Monitoring of Neurotransmitters - a Spectroscopic Analysis  

NASA Astrophysics Data System (ADS)

In this work we demonstrate the capability of confocal Raman mapping spectroscopy for simultaneously and locally detecting important compounds in neuroscience such as dopamine, serotonin, and adenosine. The Raman results show shifting of the characteristic vibrations of the compounds, observations consistent with previous spectroscopic studies. Although some vibrations are common in these neurotransmitters, Raman mapping was achieved by detecting non-overlapping characteristic spectral signatures of the compounds, as follows: for dopamine the vibration attributed to C-O stretching, for serotonin the indole ring stretching vibration, and for adenosine the adenine ring vibrations. Without damage, dyeing, or preferential sample preparation, confocal Raman mapping provided positive detection of each neurotransmitter, allowing association of the high-resolution spectra with specific micro-scale image regions. Such information is particularly important for complex, heterogeneous samples, where modification of the chemical or physical composition can influence the neurotransmission processes. We also report an estimated dopamine diffusion coefficient two orders of magnitude smaller than that calculated by the flow-injection method.

Manciu, Felicia; Lee, Kendall; Durrer, William; Bennet, Kevin

2012-10-01

129

Quantum mechanical study of the structure and spectroscopic, first order hyperpolarizability, Fukui function, NBO, normal coordinate analysis of phenyl-N-(4-methyl phenyl) nitrone.  

PubMed

The title compound, Phenyl-N-(4-Methyl Phenyl) Nitrone (PN4MPN) was synthesized and characterized by FT-IR, FT-Raman and (1)HNMR, (13)CNMR spectral analysis. The molecular geometry, harmonic vibrational frequencies and bonding features of the title compound in the ground state are computed at the Hartree-Fock/6-311++G(d,p) and three parameter hybrid functional Lee-Yang-Parr/6-311++G(d,p) levels of theory. The calculated results show that the predicted geometry can well reproduce the structural parameters. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. The dipole moment (?), polarizability (?) and hyperpolarizability (?) of the investigated molecule is calculated by using HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) methods on the finite field approach. Besides, Molecular Electrostatic Potential (MEP), Natural Bond Orbital analysis (NBO) and thermodynamical properties are described from the computational process. The electron density-based local reactivity descriptor such as Fukui functions are calculated to explain the chemical selectivity or reactivity site in PN4MPN. Finally, the calculations are applied to simulated FT-IR and FT-Raman spectra of the title compound which show good agreement with observed spectra. PMID:23659952

Sheela, N R; Sampathkrishnan, S; Thirumalai Kumar, M; Muthu, S

2013-08-01

130

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, UV-Visible) study, potential energy surface scan, Fukui function analysis and HOMO-LUMO analysis of 3-tert-butyl-4-methoxyphenol by DFT methods.  

PubMed

This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400cm(-1) and 3500-100cm(-1), respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of TBMP have been discussed. The stability and charge delocalization of the molecule was studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed and the electronic properties such as HOMO and LUMO energies were determined by time-dependent TD-DFT approach with B3LYP/6-311++G (d,p) level of theory. The molecule orbital contributions are studied by density of energy states (DOSs). The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MEP). Mulliken analysis of atomic charges is also calculated. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacities, standard entropy and standard enthalpy changes with temperatures. Global hardness, global softness, global electrophilicity and ionization potential of the title compound are determined. PMID:24813291

Saravanan, S; Balachandran, V

2014-09-15

131

Spectroscopic analysis of the intrinsic chromophores within small multidrug resistance protein SugE.  

PubMed

Small multidrug resistance (SMR) protein family member, SugE, is an integral inner membrane protein that confers host resistance to antiseptic quaternary cation compounds (QCC). SugE studies generally focus on its resistance to limited substrates in comparison to SMR protein EmrE. This study examines the conformational characteristics of SugE protein in two detergents, sodium dodecyl sulphate (SDS) and dodecyl maltoside (DDM), commonly used to study SMR proteins. The influence of cetylpyridinium (CTP) and cetrimide (CET) using SugE aromatic residues (4W, 2Y, 1F) as intrinsic spectroscopic probes was also determined. Organically extracted detergent solubilized Escherichia coli SugE protein was examined by SDS-Tricine PAGE and various spectroscopic techniques. SDS-Tricine PAGE analysis of SugE in either detergent demonstrates the protein predominates as a monomer but also dimerizes in SDS. Far-UV region circular dichroism (CD) analysis determined that the overall ?-helix content SugE in SDS and DDM was almost identical and unaltered by QCC. Near-UV region CD, fluorescence, and second-derivative ultraviolet absorption (SDUV) indicated that only DDM-SugE promoted hydrophobic environments for its Trp and Tyr residues that were perturbed by QCC addition. This study identified that only the tertiary structure of SugE protein in DDM is altered by QCC. PMID:21600871

Bay, Denice C; Turner, Raymond J

2011-09-01

132

A sensitivity study on spectroscopic parameter accuracies for a mm\\/sub-mm limb sounder instrument  

Microsoft Academic Search

The purpose of this paper is to perform a detailed error analysis for a mm\\/sub-mm limb sounding instrument with respect to spectroscopic parameters. This is done in order to give some insight into the most crucial spectroscopic parameters and to work out a list of recommendations for measurements that would yield the largest possible benefit for an accurate retrieval. The

C. L. Verdes; S. A. Buehler; A. Perrin; J.-M. Flaud; J. Demaison; G. Wlodarczak; J.-M. Colmont; G. Cazzoli; C. Puzzarini

2005-01-01

133

A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies  

ERIC Educational Resources Information Center

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…

Ramos, Carlos Henrique I.

2004-01-01

134

Spectroscopic studies on the interaction between riboflavin and albumins  

NASA Astrophysics Data System (ADS)

The interactions between riboflavin (RF) and human and bovine serum albumin (HSA and BSA) were studied by using absorption and fluorescence spectroscopic methods. Intrinsic fluorescence emission spectra of serum albumin in the presence of RF show that the endogenous photosensitizer acts as a quencher. The decrease of fluorescence intensity at about 350 nm is attributed to changes in the environment of the protein fluorophores caused by the ligand. The quenching mechanisms of albumins by RF were discussed. The binding constants and binding site number were obtained at various temperatures. The distance between albumins and RF in the complexes suggests that the primary binding site for RF is close to tryptophan residue (Trp214) of HSA and Trp212 of BSA. The hydration process of albumins has also been discussed.

Zhao, Hongwei; Ge, Min; Zhang, Zhaoxia; Wang, Wenfeng; Wu, Guozhong

2006-11-01

135

Spectroscopic and Electrical Conductivity Studies of Some Semicarbazide Hydrochloride Complexes  

NASA Astrophysics Data System (ADS)

The infrared and electronic absorption spectra of semicarbazide hydrochloride and its complexes with anthracene, tetracyanoquinodimethane TCNQ, Na-fluorescein and cupferron were recorded in the regions 200-4000cm-1 and 200-400nm. The new bands that appeared in the complex spectra were assigned. The effect of the complex formation on the frequency and intensity of the active vibrational bands was also studied. The internal energy changes of the complexes were calculated in a new line of calculation to give a clear insight about the stability of the investigated complexes. The electrical conductivity of the complexes was measured in the temperature range 25-130°C. The activation energy E was calculated and discussed on the basis of the spectroscopic information.

Fadly, M.; El-Manakhly, H.

1998-11-01

136

Absorption spectroscopic studies on gamma irradiated bismuth borosilicate glasses  

NASA Astrophysics Data System (ADS)

FT-IR spectroscopic measurements have been employed to investigate the structural changes in quaternary xBi2O3-15 Na2O-(70 - x) B2O3-15 SiO2 glass system with x = 5, 10, 15, 20 and 25 (mol%). The effect of gamma irradiation in the dose range of 0.1-60 kGy on the infrared absorption spectra of these glasses is also reported. The IR spectra of the prepared samples show characteristic bands related to the sharing of triangular and tetrahedral borate and silicate groups together with Bi-O groups. The effect of the heavy metal oxide Bi2O3 on the glass composition is also studied.

Kaur, Ravneet; Singh, Surinder; Pandey, O. P.

2013-10-01

137

Molecular spectroscopic study for suggested mechanism of chrome tanned leather  

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

138

Molecular spectroscopic study for suggested mechanism of chrome tanned leather.  

PubMed

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. PMID:22225606

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

2012-03-01

139

Spectroscopic Observations and Analysis of the Peculiar SN 1999aa.  

National Technical Information Service (NTIS)

We present an extensive new time-series of spectroscopic data of the peculiar SN 1999aa in NGC 2595. Our data set includes 25 optical spectra between -11 and +58 days with respect to B-band maximum light, providing an unusually complete time history.

G. Garavini G. Folatelli A. Goobar S. Nobili G. Aldering A. Amadon

2004-01-01

140

Spectroscopic ellipsometry data analysis: measured versus calculated quantities  

Microsoft Academic Search

Spectroscopic ellipsometry is a very powerful technique for optical characterization of thin-film and bulk materials, but the technique measures functions of complex reflection coefficients, which are usually not of interest per se. The interesting characteristics, such as film thickness, surface roughness thickness and optical functions can be determined only by modeling the near-surface region of the sample Jones matrix. However,

1998-01-01

141

A spectroscopic study on applicability of spectral analysis for simultaneous quantification of L-dopa, benserazide and ascorbic acid in batch and flow systems  

NASA Astrophysics Data System (ADS)

The usefulness of derivative spectrophotometry for simultaneous assay of L-dopa, benserazide and ascorbic acid in pharmaceuticals was studied. The parameters of derivatisation depends on composition of solution in which particular compound was determined. For quantification of L-dopa in mixtures with benserazide or ascorbic acid the first derivative was used. Its determination in ternary mixture ( L-dopa + benserazide + ascorbic acid) is possible by third derivative spectra. Benserazide was assayed in presence of L-dopa using first derivative while in ternary mixture by third derivative. Direct determination of ascorbic acid is possible applying first derivative only in presence of L-dopa. The elaborated derivative spectrophotometric methods were used for assaying of L-dopa and benserazide in their commercial form "Madopar". The proposed spectrophotometric derivative method of simultaneous determination of L-dopa and benserazide was combined with FIA technique.

Karpi?ska, Joanna; Smyk, Jerzy; Wo?yniec, El?bieta

2005-11-01

142

Spectroscopic studies on HasA from Yersinia pseudotuberculosis.  

PubMed

Heme acquisition system A (HasA) is known as a hemophore in Gram-negative pathogens. The ferric heme iron is coordinated by Tyr-75 and His-32 in holo-HasA from Pseudomonas aeruginosa (HasApa). In contrast, in holo-HasA from Yersinia pseudotuberculosis (HasAyp), our spectroscopic studies suggest that only Tyr-75 coordinates to the ferric heme iron. The substitution of Gln-32 with alanine in HasAyp does not alter the spectroscopic properties, indicating that Gln-32 is not an axial ligand for the heme iron. Somewhat surprisingly, the Y75A mutant of HasAyp can capture a free hemin molecule but the rate of hemin uptake is slower than that of wild type, suggesting that the hydrophobic interaction in the heme pocket may also play a role in heme acquisition. Unlike in wild type apoprotein, ferric heme transfer from Hb to Y75A apo-HasAyp has not been observed. These results imply that coordination (bonding/interaction) between Tyr-75 and the heme iron is important for heme transfer from Hb. Interestingly, HasAyp differs from HasApa in its ability to bind the ferrous heme iron. Apo-HasAyp can capture ferrous heme and resonance Raman spectra of ferrous-carbon monoxide holo-HasAyp suggest that Tyr-75 is protonated when the heme iron is in the ferrous state. The ability of HasAyp to acquire the ferrous heme iron might be beneficial to Y. pseudotuberculosis, a facultative anaerobe in the Enterobacteriaceae family. PMID:24857805

Ozaki, Shin-Ichi; Sato, Takehiro; Sekine, Yukari; Migita, Catharina T; Uchida, Takeshi; Ishimori, Koichiro

2014-09-01

143

Spectroscopic Observations and Analysis of the Peculiar SN 1999aa  

Microsoft Academic Search

We present an extensive new time series of spectroscopic data of the peculiar SN 1999aa in NGC 2595. Our data set includes 25 optical spectra between -11 and +58 days with respect to B-band maximum light, providing an unusually complete time history. The early spectra resemble those of an SN 1991T-like object but with a relatively strong Ca H and

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

2004-01-01

144

An Overview of the Electrochemical Interface and Optical Spectroscopic Studies.  

National Technical Information Service (NTIS)

This paper reviews the present understanding of the structure of electrochemical interfaces and identifies the types of information which optical spectroscopic measurements may be able to contribute. Particularly challenging problems are the structure of ...

E. Yeager

1977-01-01

145

Transient Raman spectroscopic studies on the excited-state intramolecular reverse proton transfer in 1-hydroxyanthraquinone  

NASA Astrophysics Data System (ADS)

We carried out the transient Raman spectroscopic studies to investigate the relaxation process of the excited-state intramolecular reverse proton transfer (r-ESIPT) in 1-hydroxyanthraquinone. To assign the observed excited-state vibrational modes, we carried out the mode analysis through the ab initio calculation with HF/4-31G(d) and CIS/4-31G(d) methods. The frequency changes of the proton-transfer-related Raman modes provide more quantitative feature on the r-ESIPT process in the excited triplet-state. Especially, the solvent natures affect the relaxation process of the excited keto-tautomer.

Cho, Dae Won; Kim, Seung Hoon; Yoon, Minjoong; Jeoung, Sae Chae

2004-06-01

146

Guest gas enclathration in semiclathrates of tetra-n-butylammonium bromide: stability condition and spectroscopic analysis.  

PubMed

In this study, guest gas enclathration behavior in semiclathrates of tetra-n-butylammonium bromide (TBAB) was closely investigated through phase equilibrium measurement and spectroscopic analysis. The three-phase equilibria of semiclathrate (H), liquid water (L(W)), and vapor (V) for the ternary CH(4) + TBAB + water and CO(2) + TBAB + water mixtures with various TBAB concentrations were experimentally measured to determine the stability conditions of the double TBAB semiclathrates. Equilibrium dissociation temperatures for pure TBAB semiclathrate were also measured at the same concentrations under atmospheric conditions. The dissociation temperature and dissociation enthalpy of pure TBAB semiclathrate were confirmed by differential scanning calorimetry. The experimental results showed that the double CH(4) (or CO(2)) + TBAB semiclathrates yielded greatly enhanced thermal stability when compared with pure CH(4) (or CO(2)) hydrate. The highest stabilization effect was observed at the stoichiometric concentration of pure TBAB semiclathrate, which is 3.7 mol%. From the NMR and Raman spectroscopic studies, it was found that the guest gases (CH(4) and CO(2)) were enclathrated in the double semiclathrates. In particular, from the cage-dependent (13)C NMR chemical shift, it was confirmed that CH(4) molecules were captured in the 5(12) cages of the double semiclathrates. PMID:21749094

Lee, Seungmin; Park, Sungmin; Lee, Youngjun; Lee, Jaehyoung; Lee, Huen; Seo, Yongwon

2011-09-01

147

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

148

Spectroscopic study of sorption of nitrogen heterocyclic compounds on phyllosilicates  

SciTech Connect

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 this article show that the degree of sorption of NHCs on phyllosilicates was dependent on the nature of the participating sorbates and sorbents. Sorption of the selected NHCs was pH-dependent, with maximum sorption occurring at low pH conditions, especially at pH < pK{sub a} of the NHC. Though sorption of the cationic forms of the NHCs on clays was preferred, neutral, zwitterionic, and anionic species of NHCs also sorbed on the clay surfaces. Spectroscopic studies have shown that sorbed NHC molecules formed clusters on clay surfaces, which acted as templates for molecular aggregation. Finally, the authors have also found that the clay surfaces promoted protonation of neutral AcN molecules at low sorbate concentrations.

Chattopadhyay, S.; Traina, S.J. [Ohio State Univ., Columbus, OH (United States). School of Natural Resources] [Ohio State Univ., Columbus, OH (United States). School of Natural Resources

1999-03-02

149

Chemical, spectroscopic characterization, DFT studies and antibacterial activities in vitro of a new gold(I) complex with rimantadine  

NASA Astrophysics Data System (ADS)

A novel gold(I) complex with rimantadine (RTD) was obtained and structurally characterized by a set of chemical and spectroscopic analysis. 1H, 13C and 15N nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic measurements suggest coordination of the ligand to Au(I) through the N atom of the ethanamine group. Theoretical (DFT) calculations confirmed the IR assignments and permit proposing an optimized geometry for the complex. The gold(I)-rimantadine complex (Au-RTD) is soluble in methanol, ethanol, dimethylsulfoxide, acetone and acetonitrile. The preliminary kinetic studies based on UV-vis spectroscopic measurements indicate the stability of the compound in solution. Antibacterial activities of the complex were evaluated by an antibiogram assay. The Au-RTD complex showed an effective in vitro antibacterial activity against the Pseudomonas aeruginosa, Escherichia coli (Gram-negative), and Staphylococcus aureus (Gram-positive) bacterial strains.

Sucena, Suelen F.; Paiva, Raphael E. F.; Abbehausen, Camilla; Mattos, Ives B.; Lancellotti, Marcelo; Formiga, André L. B.; Corbi, Pedro P.

2012-04-01

150

Spectroscopic study of laser-produced plasmas in hydrogen  

SciTech Connect

A 300-mJ, 7-ns, 1064-nm pulse from a {ital Q}-switched neodymium-doped yttrium aluminum garnet laser was tightly focused into H{sub 2} at pressures of the order of 1 atm or less. Charge-coupled-device images, time-resolved schlieren, and time-resolved spectra from the vacuum ultraviolet through the visible distinguish the prompt centrally localized emission during the initial breakdown from the subsequent blast wave and shock dissociation of the gas. Schlieren images show that the shock wave expands from the center with a velocity in excess of 13 km/s, and then slows to close to sound wave speed within 1.5 {mu}s. Inside the shock front, starting with an initial electron density greater than 4{times}10{sup 18} cm{sup {minus}3} and a temperature of 10{sup 5} K, the emitting atomic gas cools and leaves a low-density core surrounded by a cylindrical shell of slowly expanding excited H about 1.5 mm from the focal axis after 8 {mu}s. The regions responsible for visible and vacuum ultraviolet emission are in local thermodynamic equilibrium. The density, temperature, and flow agree quantitatively with the predictions of Saha ionization and excitation equilibrium in a cylindrical blast wave with counterpressure. These models characterize the postplasma gas close to the region of breakdown and permit the source to be used for quantitative spectroscopic studies of atomic and molecular processes.

Kielkopf, J.F. [Department of Physics, University of Louisville, Louisville, Kentucky 40292 (United States)] [Department of Physics, University of Louisville, Louisville, Kentucky 40292 (United States)

1995-08-01

151

Comparative spectroscopic analysis of urinary calculi inhibition by Larrea Tridentata infusion and NDGA chemical extract  

NASA Astrophysics Data System (ADS)

In the present comparative spectroscopic study we try to understand calcium oxalate kidney stone formation as well as its inhibition by using a traditional medicine approach with Larrea Tridentata (LT) herbal extracts and nordihydroguaiaretic acid (NDGA), which is a chemical extract of the LT bush. The samples were synthesized without and with LT or NDGA using a simplified single diffusion gel growth technique. While the use of infusion from LT decreases the sizes of calcium oxalate crystals and also changes their structure from monohydrate for pure crystals to dihydrate for crystals grown with different amounts of inhibitor, both Raman and infrared absorption spectroscopic techniques, which are the methods of analysis employed in this work, reveal that NDGA is not responsible for the change in the morphology of calcium oxalate crystals and does not contribute significantly to the inhibition process. The presence of NDGA slightly affects the structure of the crystals by modifying the strength of the C-C bonds as seen in the Raman data. Also, the current infrared absorption results demonstrate the presence of NDGA in the samples through a vibrational line that corresponds to the double bond between carbon atoms of the ester group of NDGA.

Manciu, Felicia

2012-10-01

152

Macromolecular Fingerprinting of Sulfolobus Species in Biofilm: A Transcriptomic and Proteomic Approach Combined with Spectroscopic Analysis  

PubMed Central

Microorganisms in nature often live in surface-associated sessile communities, encased in a self-produced matrix, referred to as biofilms. Biofilms have been well studied in bacteria but in a limited way for archaea. We have recently characterized biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus, and S. tokodaii. These strains form different communities ranging from simple carpet structures in S. solfataricus to high density tower-like structures in S. acidocaldarius under static condition. Here, we combine spectroscopic, proteomic, and transcriptomic analyses to describe physiological and regulatory features associated with biofilms. Spectroscopic analysis reveals that in comparison to planktonic life-style, biofilm life-style has distinctive influence on the physiology of each Sulfolobus spp. Proteomic and transcriptomic data show that biofilm-forming life-style is strain specific (eg ca. 15% of the S. acidocaldarius genes were differently expressed, S. solfataricus and S. tokodaii had ?3.4 and ?1%, respectively). The -omic data showed that regulated ORFs were widely distributed in basic cellular functions, including surface modifications. Several regulated genes are common to biofilm-forming cells in all three species. One of the most striking common response genes include putative Lrs14-like transcriptional regulators, indicating their possible roles as a key regulatory factor in biofilm development.

2011-01-01

153

Photoacoustic FTIR spectroscopic study of undisturbed human cortical bone  

NASA Astrophysics Data System (ADS)

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 ?2 carbonate bands. The ?3 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.

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

2013-02-01

154

The spectroscopic study of building composites containing natural sorbents  

NASA Astrophysics Data System (ADS)

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.

Król, M.; Mozgawa, W.

2011-08-01

155

Spectroscopic studies (FTIR, FT-Raman and UV), potential energy surface scan, normal coordinate analysis and NBO analysis of (2R,3R,4R,5S)-1-(2-hydroxyethyl)-2-(hydroxymethyl) piperidine-3,4,5-triol by DFT methods  

NASA Astrophysics Data System (ADS)

This work presents the characterization of (2R,3R,4R,5S)-1-(2-hydroxyethyl)-2-(hydroxymethyl)piperidine-3,4,5-triol (abbreviated as HEHMPT) by quantum chemical calculations and spectral techniques. The spectroscopic properties were investigated by FT-IR, FT-Raman and UV-Vis techniques. The FT-IR spectrum (4000-400 cm-1) and FT-Raman spectrum (4000-100 cm-1) in solid phase was recorded for HEHMPT. The UV-Vis absorption spectrum of the HEHMPT that dissolved in water was recorded in the range of 100-400 nm. The structural and spectroscopic data of the molecule were obtained from B3LYP and M06-2X with 6-31G(d,p) basis set calculations. The theoretical wavenumbers were scaled and compared with experimental FT-IR and FT-Raman spectra. The complete assignments were performed on the basis of the normal co-ordinate analysis (NCA), experimental results and potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method, interpreted in terms of fundamental modes. The stable geometry of the compound has been determined from the potential energy surface scan. The stability of molecule has been analyzed by NBO analysis. The molecule orbital contributions were studied by using the total (TDOS), partial (PDOS), and overlap population (OPDOS) density of states. The electronic properties like UV spectral analysis and HOMO-LUMO energies were reported. The calculated HOMO and LUMO energies shows that charge transfer interactions taking place within the molecule. Mulliken population analysis on atomic charges is also calculated.

Isac Paulraj, E.; Muthu, S.

2013-05-01

156

Improved protocols for vibrational spectroscopic analysis of body fluids.  

PubMed

The applications of vibrational spectroscopy to the examination of human blood serum are explored. Although FTIR spectra can be recorded in aqueous solutions at (gelatin) concentrations as low as 100 mg/L, the high-wavenumber region remains obscured by water absorption. Using Raman spectroscopy, high quality spectra of gelatine solutions as low as 10 mg/L can be achieved, also covering the high-wavenumber regions. In human serum, spectral profiles are weak and partially obscured by water features. Dried deposits are shown to be physically and chemically inhomogeneous resulting in reduced measurement reproducibility. Concentration of the serum using commercially available centrifugal filter devices results in an improvement in the spectral intensity and quality. Additionally, in Raman spectroscopy, reduced background and significantly enhanced signal collection is achievable by measurement in an inverted geometry. The improved protocols for spectroscopic measurement of human serum are applicable to a range of bodily fluids and should accelerate potential clinical applications. PMID:24132993

Bonnier, Franck; Petitjean, François; Baker, Matthew J; Byrne, Hugh J

2014-04-01

157

Spectroscopic Analysis of Today's Compact Fluorescent Light Bulbs  

NASA Astrophysics Data System (ADS)

In today's consumer market, there are many different light bulbs that claim to produce `natural' light. In my research, I both quantitatively and qualitatively analyzed this claim. First, utilizing a spectroscope, I compared the spectra emitted by different brands and types of compact fluorescent light (CFL) bulbs to the spectra emitted by the Sun. Once the bulbs were quantitatively analyzed, I proceeded to qualitatively analyze them by exposing subjects to the different bulbs. The subjects were asked to rate the quality of color in different pictures illuminated by each type of CFL. From these tests, I was able to determine the ``best'' CFL bulbs, and conclude whether the health risks associated with CFL bulbs outweigh the cost savings, longevity of the bulbs, and/or quality of light benefits.

Pluhar, Edward

2012-03-01

158

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...

159

Spectroscopic studies of cathode materials for lithium-ion batteries  

Microsoft Academic Search

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

Dana Alexa Totir

2000-01-01

160

A Fluorescence Spectroscopic Study of Honey and Cane Sugar Syrup  

Microsoft Academic Search

Fluorescence spectroscopic properties of honey and cane sugar syrup were investigated in order to explore the use of optical techniques for detection of adulteration of honey with cane sugar syrup. Measurements showed that while the major contributor to the fluorescence of cane sugar syrup is the reduced form of nicotinamide adenine dinucleotide, the fluorescence of honey is dominated by flavins.

N. GHOSH; Y. VERMA; S. K. MAJUMDER; P. K. GUPTA

2005-01-01

161

Albumin adsorption on oxide thin films studied by spectroscopic ellipsometry  

Microsoft Academic Search

Thin films of tantalum, niobium, zirconium and titanium oxides were deposited by reactive magnetron sputtering and their wettability and surface energy, optical properties, roughness, chemical composition and microstructure were characterized using contact angle measurements, spectroscopic ellipsometry, profilometry, X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The purpose of the work was to correlate the surface properties of the films to the

P. Silva-Bermudez; S. E. Rodil; S. Muhl

162

Infrared Spectroscopic Methods for the Study of Lubricant Oxidation Products  

Microsoft Academic Search

Data processing techniques have been developed for the manipulation and enhancement of spectroscopic data. They have been applied to the infrared spectra of degraded base oils and lubricants to provide information on oxidation processes and additive depletion. Samples have been acquired from oils that have been subjected to laboratory scale oxidation and from lubricants during standard engine tests. Results are

John P. Coates; Lynn C. Setti

1986-01-01

163

Spectroscopic Studies of Zinc Benzenethiolate Complexes: Electron Transfer to Methyl Viologen. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

Mononuclear and tetranuclear zinc benzenethiolate complexes are studied by both spectroscopic and electrochemical methods. Zn(SPh)4 2- and Zn4(SPh)102- represent tetrahedral fragments of the cubic zinc sulfide lattice. The structured absorption spectra of...

T. Turk U. Resch M. A. Fox A. Vogler

1992-01-01

164

A Universal Fiber-Optic Spectroscope for Studying the Modulated Reflection of Semiconductor Structures  

Microsoft Academic Search

A universal fiber-optic spectroscope has been developed that allows one to study state-of-the-art semiconductor structures by various methods employing the modulated reflection of light. Among these are both the well-known traditional methods of photoreflection and electroreflection and the new methods of longitudinal current modulated reflection and below-bandgap photoreflection. The possibilities of the spectroscope are demonstrated by studies of the semiconductor

A. E. Sotnikov; M. A. Chernikov; O. A. Ryabushkin

2004-01-01

165

Vibrational Spectroscopic Studies on Some Double Alkali Tungstates Belonging to Orthorhombic Class at Room Temperature  

NASA Astrophysics Data System (ADS)

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.

Sharaff, Usha; Bajpai, P. K.; Choudhary, R. N. P.

2011-11-01

166

The electronic structure of pyracene: a spectroscopic and computational study.  

PubMed

We report a synthetic, spectroscopic and computational study of the polycyclic aromatic molecule pyracene, which contains aliphatic five-membered rings annealed to a naphthalene chromophore. An improved route to synthesize the compound is described. Gas-phase IR and solid-state Raman spectra agree with a ground-state D2h structure. The electronically excited S1 A(1)B3u state has been studied by resonance-enhanced multiphoton ionisation. An adiabatic excitation energy T0 = 30,798 cm(-1) (3.818 eV) was determined. SCS-ADC(2) calculations found a D2h minimum energy structure of the S1 state and yielded an excitation energy of +3.98 eV, including correction for zero point vibrational energy. The spectrum shows a rich low-frequency vibrational structure that can be assigned to the overtones of out-of-plane deformation modes of the five-membered rings by comparison with computations. The appearance of these modes as well as the frequency reduction in the excited state indicate that the potential in the S1 state is very flat. At higher excess energies most bands can be assigned to fundamentals, overtones and combination bands of either totally symmetric ag modes or of b2g modes that appear due to vibronic coupling. Lifetimes between 43 ns and 76 ns were measured for a number of vibronic bands. For the S2 state an equilibrium geometry with a non-planar carbon framework was computed. In addition a signal from the pyracene dimer was present. The spectrum shows several broad and structureless transitions. The origin band has a maximum at around 329 nm (30,400 cm(-1)). Again lifetimes between 60 ns and 70 ns were found. The dimer ion signal rises within less than 10 ps. Computations show that a crossed geometry with the long axis of one unit aligned with the short axis of the second constitutes the most stable structure. The broadening of the bands is most likely caused by excimer formation. PMID:23598438

Auerswald, Johannes; Engels, Bernd; Fischer, Ingo; Gerbich, Thiemo; Herterich, Jörg; Krueger, Anke; Lang, Melanie; Schmitt, Hans-Christian; Schon, Christof; Walter, Christof

2013-06-01

167

Spectroscopic observations and analysis of the peculiar SN1999aa  

SciTech Connect

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

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

2003-12-10

168

Spectroscopic Analysis of Hydrothermal Alteration in Geothermal Drill Core  

NASA Astrophysics Data System (ADS)

Water geochemistry can vary with depth and location within a geothermal reservoir, owing to natural factors such as changing rock type, gas content, fluid source and temperature. The interaction of these variable fluids with the host rock will cause changes in the host rock and create a variety of alteration minerals and precipitates. These alteration products can suggest regions of past fluid flow in the subsurface and their mineralogy can be used to determine fluid temperature. Infrared spectroscopy is particularly good at identifying a wide variety of hydrothermal alteration minerals, requires no sample preparation, and is especially helpful in discrimination among clay minerals. We have applied traditional remote sensing hyperspectral techniques in several pilot studies of geothermal drill core and chip analysis. We have surveyed a variety of samples, including drill chip boards, boxed core, and drill cuttings from envelopes and chip trays. Alteration mineralogy can indicate both the presence of thermal fluids and the hottest fluid temperature. These preliminary studies have established reliable methods for core/chip surveys that can rapidly measure samples with high depth resolution and show the efficiency of the technique to sample continuously and provide alteration logs similar to geophysical logs. We have successfully identified a wide variety of phyllosilicates, zeolites, opal, calcite, and iron oxides and hydroxides in drill core and cuttings from geothermal wells. In high vertical resolution measurements (every 10') we note depth-associated changes in alteration minerals, patterns or zones. Temperature dependent mineral assemblages are found, both gradational with depth and as narrow zones associated with vein or fracture fill. Amorphous silica is clearly identified and seen only in the highest temperature wells. We can readily identify montmorillonite/illite transitions that may be associated with Na/Ca/K variation and may eventually be used for geothermometry. We will present an overview of these past studies, with specific comparisons to other geochemical analysis for the Humboldt House location.

Calvin, W. M.; Littlefield, E. F.

2012-12-01

169

Microwave spectroscopic studies of obliquely deposited Co\\/Cr trilayers  

Microsoft Academic Search

Polycrystalline Co\\/Cr trilayers were grown by e-beam evaporation in ultra-high vacuum, with Co deposited at various oblique angles to the substrate. Microwave spectroscopic experiments were performed with the applied field in the in-plane and out-of-plane configurations to explore the resultant changes in anisotropy and interlayer coupling. The in-plane anisotropy, effective magnetisation and interlayer coupling strength are found to be greatly

M. Jackson; G. Short; T. Mendus; S. M. Thompson; E. Ho; J. S. S. Whiting

1998-01-01

170

Infrared spectroscopic analysis of skin tumor of mice treated with several medicinal plants  

PubMed Central

Objective To evaluate the differences between cancerous tissue, drug treated tissue and its corresponding normal tissue by infrared spectroscopic analysis. Methods Methanolic extracts of Azadirachta indica, Ocimum sanctum, Aloe barbandesis, Tinospora cordifolia and Triticum aestivum were assessed for the isolation and purification of active compound. After that, combine crude and combine isolated samples were prepared. Skin tumor was induced by topical application of 7, 12-dimethyl benz (a) anthracene and promoted by croton oil in Swiss albino mice. To assess the chemopreventive potential of different drugs, it was administered at a concentration of 400 mg/kg body weight daily up to 16 weeks. Fourier transform infrared spectroscopy analysis was used to differentiate the drug treated tissues with the normal and cancerous tissue. In the present study, spectra of different tissues were recorded in the range of 400-4?000 cm?1. Results The results of the present study have shown that the remarkable difference exists between the IR spectra of normal, drugs treated and cancerous tissue in terms of frequencies and intensities of prominent bands of cellular biomolecules. Conclusions Fourier transform infrared spectroscopy analysis suggests the chemopreventive effect of above treated drugs and the best result was observed in combine crude sample and in combine isolated sample or synergistic effect of individual crude and isolated extract in 7, 12-dimethyl benz (a) anthracene croton oil induced skin carcinogenesis in Swiss albino mice.

Ali, Huma; Dixit, Savita

2013-01-01

171

Spectroscopic and thermal studies of PS\\/PVAc blends  

Microsoft Academic Search

Polystyrene and polyvinyl acetate (PS\\/PVAc) films were blended with different contents using casting method. The effect of PS content on PVAc blends was investigated by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Ultra violet and visible studies (UV\\/VIS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Significant changes in FT-IR, XRD and DSC analysis are observed which reveals an interactions

I. S. Elashmawi; N. A. Hakeem; E. M. Abdelrazek

2008-01-01

172

Varimax extended rotation applied to multivariate spectroscopic image analysis  

Microsoft Academic Search

A new approach for spectral image analysis called the Varimax extended rotation (VER) has been developed. VER employs a four-step procedure to resolve image data. In the first step, the data are pretreated to ensure they are is in a form suitable for principal component analysis. The second step involves reducing the dimensionality of the data using principal component analysis.

Barry K. Lavine; Charles E. Davidson; Jason Ritter; David J. Westover; Thomas Hancewicz

2004-01-01

173

Spectroscopic study of the O-type runaway supergiant HD 195592  

NASA Astrophysics Data System (ADS)

The scope of this paper is to perform a detailed spectroscopic study of the northern O-type supergiant HD 195592. We use a large sample of high quality spectra in order to investigate its multiplicity, and to probe the line profile variability. Our analysis reveals a clear spectroscopic binary signature in the profile of the He I? 6678 line, pointing to a probable O + B system. We report on low amplitude radial velocity variations in every strong absorption line in the blue spectrum of HD 195592. These variations are ruled by two time-scales, respectively, of 5.063 and about 20 days. The former is firmly established, whilst the latter is poorly constrained. We report also on a very significant line profile variability of the H ? line, with time scales strongly related to those of the radial velocities. Our results provide significant evidence that HD 195592 is a binary system, with a period that might be the variability time-scale of about 5 days. The second time scale may be the signature of an additional star moving along a wider orbit provided its mass is low enough, even though direct evidence for the presence of a third star is still lacking. Alternatively, the second time-scale may be the signature of a variability intrinsic to the stellar wind of the primary, potentially related to the stellar rotation.

De Becker, M.; Linder, N.; Rauw, G.

2010-01-01

174

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

175

Raman Spectroscopic Methods for Classification of Normal and Malignant Hypopharyngeal Tissues: An Exploratory Study  

PubMed Central

Laryngeal cancer is more common in males. The present study is aimed at exploration of potential of conventional Raman spectroscopy in classifying normal from a malignant laryngopharyngeal tissue. We have recorded Raman spectra of twenty tissues (aryepiglottic fold) using an in-house built Raman setup. The spectral features of mean malignant spectrum suggests abundance proteins whereas spectral features of mean normal spectrum indicate redundancy of lipids. PCA was employed as discriminating algorithm. Both, unsupervised and supervised modes of analysis as well as match/mismatch “limit test” methodology yielded clear classification among tissue types. The findings of this study demonstrate the efficacy of conventional Raman spectroscopy in classification of normal and malignant laryngopharyngeal tissues. A rigorous evaluation of the models with development of suitable fibreoptic probe may enable real-time Raman spectroscopic diagnosis of laryngopharyngeal cancers in future.

Pujary, Parul; Maheedhar, K.; Krishna, C. Murali; Pujary, Kailesh

2011-01-01

176

Electron spectroscopic studies of the neutralization of slow multicharged ions during interactions with a metal surface  

SciTech Connect

Recent experimental results of electron spectroscopic studies of the neutralization and relaxation of slow multicharged ions interacting with metal surfaces are summarized. Discussed are measurements of projectile K-Auger electron emission during interactions of N{sup 6+} ions with clean and cesiated Au, as well as clean Cu single crystal targets. While the dominant component in the measured K-Auger spectra is shown to be due to sub-surface electron emission, at incident perpendicular velocities below about 10{sup {minus}2} au, small features become evident in the measured K-Auger spectra that are consistent with above surface projectile electron emission. Experimental results are compared with results of modelling studies of above- and sub-surface electron emission. Also presented are measurements of low energy electron emission during multicharged ion-surface interactions, together with a discussion and analysis of the various contributing low energy emission mechanisms.

Meyer, F.W.; Folkerts, L.; Havener, C.C.; Hughes, I.G.; Overbury, S.H.; Zehner, D.M.; Zeijlmans van Emmichoven, P.A.

1993-09-01

177

Proficiency test for gamma spectroscopic analysis with a simulated fission product reference spectrum.  

PubMed

Within the proficiency test programme for the radionuclide laboratories supporting the verification of the Comprehensive Nuclear-Test-Ban Treaty, a simulated gamma spectrum with the characteristics of an atmospheric nuclear test was used as reference material. The spectrum was produced by the MCNP-based Virtual Gamma Spectroscopy Laboratory (VGSL), using analysis results of a historical measurement of nuclear weapons debris as input. The method was found suitable for a proficiency test assessing laboratories' gamma spectroscopic analysis. PMID:16567096

Karhu, P; De Geer, L-E; McWilliams, E; Plenteda, R; Werzi, R

2006-01-01

178

Noninvasive spectroscopic analysis of fluoropyrimidine metabolism in cultured tumor cells.  

PubMed

Nuclear magnetic resonance spectroscopy is a technique that may be used noninvasively to follow the intracellular metabolism of fluorinated antimetabolites such as 5-fluorouracil (FUra) and 5-fluorouridine. Intracellular 19F spectral peaks are assigned by comparison with the pH-dependent chemical shifts measured for eight commercially available fluoropyrimidine metabolites as well as by comparison with the literature recorded values of five known catabolites of FUra. Five murine and human tumor cell lines (N1S1, Sarcoma 180, L1210, HL-60, and Mia-PaCa) were exposed in vitro for 24 h to cytostatic doses of FUra or 5-fluorouridine. Treated cells were harvested and analyzed immediately or following a subsequent incubation under either nutrient-rich or nutrient-poor conditions. A major narrow component peak at 4.6-4.9 ppm was observed in all cell samples analyzed immediately after treatment. This peak was identified as intracellular FUra nucleotides, and its T1 value was approximately 800 ms. No fluoropyrimidine catabolites were detectable in any of the treated cell lines. Free FUra could be measured in cells only after subsequent incubation under nutrient-poor conditions, and this was associated with a decline in the prominent FUra nucleotide peak. In treated cells chased with drug-free media containing 1 microM thymidine, spectra revealed a broad component signal underlying and downfield from the narrow nucleotide-containing peak. By biochemically fractionating treated cells into an acid-soluble fraction and phenol-purified cytoplasmic and nuclear RNA extracts, we were able to completely separate the nucleotide peak from the broad component signal resulting from FUra incorporation into RNA. Thymidine produced a marked enhancement of this 19F signal into both cytoplasmic and nuclear RNA without affecting the nucleotide signal from the acid-soluble fraction. The present ability of nuclear magnetic resonance to monitor the metabolic channeling of fluoropyrimidines in intact tumor cells suggests that future spectroscopic imaging of patients treated with fluorinated antimetabolites may provide clinically important information about tumor biochemistry and drug sensitivity. PMID:3456267

Keniry, M; Benz, C; Shafer, R H; James, T L

1986-04-01

179

Synthesis and spectroscopic analysis of modified bile salts.  

PubMed

For the study of hepatic bile acid transport in vivo, a series of modified bile salts were synthesized. The N-cholyl derivatives of L-leucine, L-alanine, D-alanine, beta-alanine, L-proline, and gamma-amino-butyric acid were prepared from cholic acid, ethyl chloroformate and the corresponding amino acid. Structural analysis of products was carried out mainly by electron impact mass spectrometry (20 eV) of the methyl ester/acetate derivatives. In all EI spectra, fragments in the lower mass region included McLafferty rearrangement ions (beta-cleavage) and product ions of gamma-cleavage in the vicinity of the amide linkage. In the upper mass region, fragmentation was characterized by consecutive eliminations of ketene and/or acetic acid from low intensity molecular ions. The purity of the products and their molecular weights were checked by a novel ionization technique in mass spectrometry, fast atom bombardment (FAB) mass spectrometry. FAB spectra were obtained from underivatized bile salts. The spectra were characterized by ions formed by attachment of a proton or an alkali ion to the bile salt to give intense M+H, M+Na, or M+K ions, which then showed little fragmentation. PMID:6658870

Ballatore, A M; Beckner, C F; Caprioli, R M; Hoffman, N E; Liehr, J G

1983-02-01

180

Picosecond flash spectroscopic studies on ultraviolet stabilizers and stabilized polymers  

NASA Technical Reports Server (NTRS)

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.

Scott, G. W.

1982-01-01

181

Spectroscopic Analysis of Hot Subdwarf Stars in the Globular Cluster NGC 6752  

NASA Astrophysics Data System (ADS)

We present a spectroscopic analysis of three hot subdwarf stars that are located in the globular cluster NGC 6752. The stars are B0852, B1754, and B2004. The analysis is based on observations obtained with the Far Ultraviolet Spectroscopic Explorer and the Cosmic Origins Spectrograph. The stars have effective temperatures ranging from 37,000 K to 40,000 K and gravities ranging from log g = 5.00 to 5.25. These parameters suggest that they are post-extreme horizontal branch stars. Our NLTE spectral synthesis analysis reveals that the abundances of C, O, Si, P, and S are subsolar by factors ranging from 10 to 1000. The abundances of N are slightly subsolar. The abundances of Fe and Ni observed in the star B1754 are subsolar and solar, respectively. The C, N, O, Si, P, S, and Fe abundances are consistent with the abundances observed in field sdB stars.

Chayer, P.; Dixon, W.

2014-04-01

182

FTIR spectroscopic studies of lipid dynamics in phytosphingosine ceramide models of the stratum corneum lipid matrix.  

PubMed

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. PMID:15752463

Rerek, Mark E; Van Wyck, Dina; Mendelsohn, Richard; Moore, David J

2005-03-01

183

Inhibitory effect of morin on tyrosinase: Insights from spectroscopic and molecular docking studies.  

PubMed

Tyrosinase is a key enzyme in the production of melanin in the human body, excessive accumulation of melanin can lead to skin disorders. Morin is an important bioactive flavonoid compound widely distributed in plants and foods of plant origin. In this study, the inhibitory kinetics of morin on tyrosinase and their binding mechanism were determined using spectroscopic and molecular docking techniques. The results indicate that morin reversibly inhibited tyrosinase in a competitive manner through a multi-phase kinetic process. Morin was found to bind to tyrosinase at a single binding site mainly by hydrogen bonds and van der Waals forces. Analysis of circular dichroism spectra revealed that the binding of morin to tyrosinase induced rearrangement and conformational changes of the enzyme. Moreover, molecular docking results suggested that morin competitively bound to the active site of tyrosinase with the substrate levodopa. PMID:24912720

Wang, Yajie; Zhang, Guowen; Yan, Jiakai; Gong, Deming

2014-11-15

184

Micro-Ft Spectroscopic Studies of Breast Tissues  

NASA Astrophysics Data System (ADS)

Micro-FT-IR spectroscopy was used to study breast cancer tissues and, in particular osteosarcoma tissue. By analysing the spectra, we have found characteristic bands in the infrared regions, where the main components of these signature bands are located. In the region between 1680-1660 cm-1 are found the characteristic bands of Amide I and II of proteins. The bands, which correspond to the vibrations of the phosphate groups, are found in the region near 1140-900 cm-1. These characteristic bands have been monitored as a function of the degree of cancer progression. The results have been obtained with chemometric methods, such as cluster analysis, principal component analysis and custom analysis in order to distinguish the neoplastic zones from the normal zones.

Anastassopoulou, J.; Arapantoni, P.; Boukaki, E.; Konstadoudakis, S.; Theophanides, T.; Valavanis, C.; Conti, C.; Ferraris, P.; Giorgini, G.; Sabbatini, S.; Tosi, G.

185

Artificial neural networks for plasma x-ray spectroscopic analysis  

SciTech Connect

Modern diagnostic instrumentation produces a vast amount of data that often requires substantial analysis efforts. New methods are needed to improve the efficiency of the analysis process. Artificial neural networks have been applied to a variety of signal processing and image recognition problems. The feed-forward, back-propagation technique is well suited for the analysis of scientific laboratory data, which is viewed as a pattern-matching problem. We summarize the concepts and algorithms as implemented on a personal computer, and illustrate the method using a nonlocal thermodynamic equilibrium theoretical atomic physics model for {ital k}-shell x-ray spectroscopy of a high density, high temperature aluminum plasma. Extensions to other types of spectroscopy data analysis are discussed.

Larsen, J.T. (Cascade Applied Sciences, Inc., P. O. Box 4477, Boulder, Colorado 80306 (United States)); Morgan, W.L. (Kinema Research, 18720 Autumn Way, Monument, Colorado 80132 (United States)); Goldstein, W.H. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1992-10-01

186

Analysis of Spectroscopic Radiation Portal Monitor Data Using Principal Components Analysis  

SciTech Connect

Many international border crossings screen cargo for illicit nuclear material using radiation portal monitors (RPMs) that measure the gamma-ray flux emitted by vehicles. Screening often consists of primary, which acts as a trip-wire for suspect vehicles, and secondary, which locates the radiation source and performs isotopic identification. The authors present a method of anomaly detection for primary screening that uses past observations of gamma-ray signatures to define an expected benign vehicle population. Newly acquired spectra are then compared to this expected population using statistical criteria that reflect acceptable alarm rates and probabilities of detection. Shown here is an analysis of spectroscopic RPM data collected at an international border crossing using this technique. The raw data were analyzed to develop an expected benign vehicle population by decimating the original pulse-height channels, extracting composite variables with principal components analysis, and estimating variance-weighted distances from the ''mean vehicle spectra'' with the Mahalanobis distance metric. The following analysis considers data acquired with both NaI(Tl)-based and plastic scintillator-based RPMs. For each system, performance estimates for anomaly sources are compared to common nuisance sources. The algorithm reported here shows promising results in that it is more sensitive to the anomaly sources than common nuisance sources for both RPM types.

Runkle, Robert C.; Tardiff, Mark F.; Anderson, K K.; Carlson, Deborah K.; Smith, L E.

2006-06-01

187

Swiss bare mice: a suitable model for transcutaneous in vivo Raman spectroscopic studies of breast cancer.  

PubMed

Breast cancer is the most common cancer affecting females worldwide. As early detection results in better prognosis, screening tools for breast cancer are being explored. Raman spectroscopy, a rapid, objective, and noninvasive tool, has shown promising results in the diagnosis of several cancers including breast cancer. For development as a screening tool, a study of spectral signatures associated with breast cancer progression is imperative. However, such studies are not possible in human subjects. Hence, there is a need for a suitable animal model, which is conducive to transcutaneous in vivo Raman spectroscopic measurements of breast with minimal interference from skin and hair and has contribution from functional mammary epithelium of breast. In this study, rodent models like C57, Swiss albino, Swiss bare, agouti mice, and Sprague-Dawley rats were evaluated. Among these models, transcutaneous breast spectra of hairless Swiss bare mice have the best signal-to-noise ratio and were closest to reported ex vivo as well as intraoperative in vivo human breast spectra. Principal component-linear discriminant analysis of several anatomical sites confirms minimal skin interference and suggests contribution from functional mammary epithelium of breast. Moreover, transcutaneous spectra from normal breast and breast tumors of Swiss bare mice could be classified with 99% efficiency, which is better than the previous reports. Thus, Swiss bare mice model may be better suited for transcutaneous in vivo Raman spectroscopic studies of breast physiology and pathology, especially breast cancer. Prospectively, in addition to cancer progression, breast-to-bone metastasis can also be studied, since these anatomical sites can be uniquely classified. PMID:23708992

Bhattacharjee, T; Kumar, Piyush; Maru, G; Ingle, A; Krishna, C Murali

2014-01-01

188

Spectroscopic Analysis of Plasma Gradients in ICF Imploded Cores  

NASA Astrophysics Data System (ADS)

X-ray spectroscopy of laser-driven, imploded cores has proved to be a powerful diagnostic of spatially-averaged temperature and density plasma conditions at the collapse of ICF implosion experiments. Temperature and density time histories can be extracted from the analysis of time-resolved X-ray line spectra. The next step in the spectroscopy of imploded cores is the bracketing of the core plasma gradients as a function of time. The determination of core plasma gradients in laser-driven implosions is a problem of fundamental as well as practical importance. Knowledge of core gradients will result in an improved characterization of core plasma dynamics, and it will also provide new data for more detailed benchmarks of hydrodynamic simulations. To this end, we discuss a technique which is based on the self-consistent, simultaneous simulation and analysis of time-resolved X-ray line spectra and time-resolved X-ray monochromatic images. Abel inversion of X-ray monochromatic images provides line emissivity spatial profiles; this information is critical for the determination of spatial gradients in the core. To illustrate the application of this technique, we use it to analyze synthetic data obtained from 1D LILAC hydrodynamic simulations of OMEGA implosions. In this case, the analysis relies on the Ar He-beta line and associated Li-like satellites spectral feature. Instrumental effects are also included in the analysis. We also discuss the algorithms developed for the analysis of the data and their code implementation.

Golovkin, Igor; Mancini, Roberto; Delettrez, Jacques; Klein, Lewis; Lee, Richard

1999-11-01

189

IR spectroscopic study of thioacrolein and its photoisomerization to methylthioketene  

Microsoft Academic Search

The molecules of thioacrolein (1) and metylthioketene (3), which are labile under normal conditions, have been studied by the matrix Fourier transform infrared spectroscopy method. Compound1 was obtained by vacuum pyrolysis (1120 K, 10-4 Torr) of diallyl sulfide. The analysis of its IR spectrum shows that1 exists as a mixture ofs-trans ands-cis conformers. UV irradiation (? > 248 nm) of

V. A. Korolev; E. G. Baskir

1995-01-01

190

Chemical factor analysis of skin cancer FTIR-FEW spectroscopic data  

NASA Astrophysics Data System (ADS)

Chemical Factor Analysis (CFA) algorithms were applied to transform complex Fourier transform infrared fiberoptical evanescent wave (FTIR-FEW) normal and malignant skin tissue spectra into factor spaces for analysis and classification. The factor space approach classified melanoma beyond prior pathological classifications related to specific biochemical alterations to health states in cluster diagrams allowing diagnosis with more biochemical specificity, resolving biochemical component spectra and employing health state eigenvector angular configurations as disease state sensors. This study demonstrated a wealth of new information from in vivo FTIR-FEW spectral tissue data, without extensive a priori information or clinically invasive procedures. In particular, we employed a variety of methods used in CFA to select the rank of spectroscopic data sets of normal benign and cancerous skin tissue. We used the Malinowski indicator function (IND), significance level and F-Tests to rank our data matrices. Normal skin tissue, melanoma and benign tumors were modeled by four, two and seven principal abstract factors, respectively. We also showed that the spectrum of the first eigenvalue was equivalent to the mean spectrum. The graphical depiction of angular disparities between the first abstract factors can be adopted as a new way to characterize and diagnose melanoma cancer.

Bruch, Reinhard F.; Sukuta, Sydney

2002-03-01

191

Spectroscopic ellipsometric studies of randomly distributed plasmonic Gallium nanoparticles  

NASA Astrophysics Data System (ADS)

Ultraviolet surfaced-enhanced Raman scattering (UV-SERS) was recently observed using randomly distributed Gallium nanoparticles (Ga NPs) deposited on sapphire by molecular beam expitaxy at room temperature. Atomic force and scanning electron microscopies revealed that the radii of the hemispheroid NPs follow unimodal or bimodal pseudo Gaussian distributions whose mean diameters increase with increasing Ga dosage (i.e. growth time). Variable angle spectroscopic ellipsometric measurements were then performed on Ga NP ensembles to explore the correlation between the polarimetric optical response and the local morphology. An effective medium composed of single or double Lorentzian oscillators was found to reproduce the optical response of Ga NP ensembles with resonance frequencies that decrease monotonically with increasing NP size. In addition, a strong depolarization response was observed for near-normal incidence. Interestingly, the sample for which the depolarization peak was closest to the 325nm laser excitation wavelength was the sample with the highest SERS enhancement factor.

Yang, Yang; Kim, Tong-Ho; Akozbek, Neset; Brown, April; Everitt, Henry

2013-03-01

192

In-situ spectroscopic studies of electrochromic tungsten oxide films  

NASA Astrophysics Data System (ADS)

Tungsten oxide thin films were prepared using an ethanolic solution of tungsten hexachloride (WCl6) by sol-gel spin coating. The films were spin coated on indium tin oxide (ITO) coated glass substrate at temperatures in the range of 100 to 450 degree(s)C. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM) UV- visible spectroscopy and cyclic voltammetry (CV). XRD showed that they had a polycrystalline WO3 structure for heat treatment temperatures at above 350 degree(s)C. The SEM examinations showed that the surface texture was very uniform and homogeneous. In situ electrochemical reduction of WO3/ITO (2M HCl) produced a blue color in less than a second. Coloration efficiency (CE) was found to be 21 cm2/mC. In situ spectroscopic investigations showed that these films could be used as a working electrode in electrochromic devices.

Ozer, Nilgun; Demirbas, Muharrem; Ozyurt, Secuk

2001-11-01

193

Structural and spectroscopic studies of a commercial glassy carbon  

NASA Astrophysics Data System (ADS)

Glassy carbon is a form of carbon made by heating a phenolic resin to high temperature in an inert atmosphere. It has been suggested that it is composed of fullerene-like structures. The aim of the present work was to characterize the material using both structural (neutron diffraction and transmission electron microscopy) and spectroscopic (inelastic neutron scattering, Raman and X-ray photoelectron spectroscopies) methods. We find no evidence to support the suggestion of fullerene-like material being present to a significant extent, rather the model that emerges from all of the techniques is that the material is very like amorphous carbon, consisting of regions of small graphite-like basic structural units of partly stacked but mismatched structure with the edges terminated by hydrogen or hydroxyls. We do find evidence for the presence of a small quantity of water trapped in the network and suggest that this may account for batch-to-batch variation in properties that may occur.

Parker, Stewart F.; Imberti, Silvia; Callear, Samantha K.; Albers, Peter W.

2013-12-01

194

Spectroscopic study of carbonaceous dust particles grown in benzene plasma  

SciTech Connect

Carbonaceous dust particles have been synthesized from benzene using an rf glow discharge. Scanning electron microscope inspection revealed that the plasma-synthesized dust particles can be classified into two types. Shell-structured dust particles showed a wide size distribution from 3 to40 {mu}m. The other type, with different degrees of aggregation, appeared to be dense and spherical with a very distinctive yellow color and size distribution from 100 nm to 2 {mu}m. Analyses using micro-Raman and Fourier transform infrared microscopy indicated that the main components of the dust particles are polyphenyls and hydrogenated amorphous carbon (HAC). The luminescence background in Raman spectra and the infrared C-H stretching vibrational features observed around 3.4 {mu}m for the dust particles are attributed to HAC. The formation mechanisms and spectroscopic characterization of carbonaceous dust particles are discussed.

Lee, Szetsen; Chen, H.-F.; Chin, C.-J. [Department of Chemistry, Center for Nano-technology, and R and D Center for Membrane Technology, Chung Yuan Christian University, 200 Jongbei Road, Jhongli City, Taoyuan County, 32023, Taiwan (China)

2007-06-01

195

Mass spectroscopic study on the carbothermic reduction of plutonium dioxide  

NASA Astrophysics Data System (ADS)

Mass spectroscopic measurements of actinide-bearing species, effusing from the Knudsen cell containing a mixture of PuO 2 + 3C, were performed in the temperature range from 1593 to 1673 K. The change of P Pu and p Puo accompanied by the progress of the carbothermic reduction indicated that the reaction proceeded on the Pu-C-O phase diagram to the final product, PuC xO y + PuC 1.5. The Pco in the reaction process was calculated from p Pu and P PuO values with a thermodynamical aid. It was confirmed that P co above the PuC xO y + PuC 1.4 region became less than p Pu and an invariable chemical composition of plutonium monoxycarbide in equilibrium with PuC 1.5 was attained.

Ohmichi, Toshihiko; Suzuki, Yasufumi; Arai, Yasuo; Sasayama, Tatsuo; Maeda, Atsushi

1986-07-01

196

Models of chemical biosignatures - a vibrational spectroscopic study  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

197

Spectroscopic and thermal studies of PS/PVAc blends  

NASA Astrophysics Data System (ADS)

Polystyrene and polyvinyl acetate (PS/PVAc) films were blended with different contents using casting method. The effect of PS content on PVAc blends was investigated by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Ultra violet and visible studies (UV/VIS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Significant changes in FT-IR, XRD and DSC analysis are observed which reveals an interactions between the two polymers and PS/PVAc blends had good or certain miscibility. XRD scans show some changes in the intensity and the height of the amorphous halos with increased PS. UV/VIS analysis revealed that the optical band gap decreases with increasing content of PS from 5 to 4.11 eV. A single glass transition temperature for each blend was observed, this DSC results supported that the miscibility existed in the blend. The apparent activation energy (E) of the blends was evaluated using TGA analysis. The value of E was increased with the increase of PS content.

Elashmawi, I. S.; Hakeem, N. A.; Abdelrazek, E. M.

2008-10-01

198

Thermal treatment of weddellite—a Raman and infrared emission spectroscopic study  

Microsoft Academic Search

Thermal transformations of natural calcium oxalate dihydrate known in mineralogy as weddellite have been undertaken using a combination of Raman microscopy and infrared emission spectroscopy. The vibrational spectroscopic data was complimented with high resolution thermogravimetric analysis combined with evolved gas mass spectrometry. TG–MS identified three mass loss steps at 114, 422 and 592°C. In the first mass loss step water

Ray L. Frost; Matt L. Weier

2003-01-01

199

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

NASA Technical Reports Server (NTRS)

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.

Allamandola, L. J.

1989-01-01

200

Spectroscopic and photometric study of two B-type pulsators in eclipsing systems  

NASA Astrophysics Data System (ADS)

Pulsating stars in eclipsing binary systems play an important role in asteroseismology. The combination of their spectroscopic and photometric orbital solutions can be used to determine, or at least to constrain, the masses and radii of components. To successfully perform any seismic modelling of a star, one has to identify at least some of the detected modes, which requires precise time-series photometric and spectroscopic observations. This work presents a progress report on the analysis of two ? Cephei-type stars in eclipsing binaries: HD 101794 (V916 Cen) and HD 167003 (V4386 Sgr).

Drobek, Dominik; Pigulski, Andrzej

2014-02-01

201

Raman spectroscopic analysis of human tissue engineered oral mucosa constructs (EVPOME) perturbed by physical and biochemical methods  

NASA Astrophysics Data System (ADS)

We show the application of near-infrared Raman Spectroscopy to in-vitro monitoring of the viability of tissue constructs (EVPOMEs). During their two week production period EVPOME may encounter thermal, chemical or biochemical stresses that could cause development to cease, rendering the affected constructs useless. We discuss the development of a Raman spectroscopic technique to study EVPOMEs noninvasively, with the ultimate goal of applying it in-vivo. We identify Raman spectroscopic failure indicators for EVPOMEs, which are stressed by temperature, and discuss the implications of varying calcium concentration and pre-treatment of the human keratinocytes with Rapamycin. In particular, Raman spectra show correlation of the peak height ratios of CH2 deformation to phenylalanine ring breathing, providing a Raman metric to distinguish between viable and nonviable constructs. We also show the results of singular value decomposition analysis, demonstrating the applicability of Raman spectroscopic technique to both distinguish between stressed and non-stressed EVPOME constructs, as well as between EVPOMEs and bare AlloDerm® substrates, on which the oral keratinocytes have been cultured. We also discuss complications arising from non-uniform thickness of the AlloDerm® substrate and the cultured constructs, as well as sampling protocols used to detect local stress and other problems that may be encountered in the constructs.

Khmaladze, Alexander; Ganguly, Arindam; Raghavan, Mekhala; Kuo, Shiuhyang; Cole, Jacqueline H.; Marcelo, Cynthia L.; Feinberg, Stephen E.; Izumi, Kenji; Morris, Michael D.

2012-02-01

202

M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared  

NASA Astrophysics Data System (ADS)

Context. The relatively wide spread in the derived metallicities ([Fe/H]) of M dwarfs shows that various approaches have not yet converged to consistency. The presence of strong molecular features and incomplete line lists for the corresponding molecules have made determining the metallicity of M dwarfs difficult. Furthermore, the faint M dwarfs require long exposure times for the signal-to-noise ratio needed for a detailed spectroscopic abundance analysis. Aims: We present a high-resolution (R ~ 50 000) spectroscopic study of a sample of eight single M dwarfs and three wide-binary systems observed in the infrared J band. Methods: The absence of large molecular contributions allows for a precise continuum placement. We derived metallicities based on the best fit of synthetic spectra to the observed spectra. To verify the accuracy of the applied atmospheric models and test our synthetic spectrum approach, three binary systems with a K-dwarf primary and an M-dwarf companion were observed and analysed along with the single M dwarfs. Results: We obtain good agreement between the metallicities derived for the primaries and secondaries of our test binaries, thereby confirming the reliability of our method of analysing M dwarfs. Our metallicities agree well with some earlier determinations, and deviate from others. Conclusions: We conclude that spectroscopic abundance analysis in the J band is a reliable method for establishing the metallicity scale for M dwarfs. We recommend its application to a larger sample covering lower, as well as higher, metallicities. Further prospects for the method include abundance determinations for individual elements. Based on data obtained at ESO-VLT, Paranal Observatory, Chile, Program ID 082.D-0838(A) and 084.D-1042(A).Table 2 is available in electronic form at http://www.aanda.orgElectronic version of the spectra is only available at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A33

Önehag, A.; Heiter, U.; Gustafsson, B.; Piskunov, N.; Plez, B.; Reiners, A.

2012-06-01

203

An algorithm for least squares analysis of spectroscopic data  

Microsoft Academic Search

This paper describes a variant of the Gauss-Newton-Hartley algorithm for nonlinear least squares, in which aQR implementation is used to solve the linear least squares problem. We follow Grey's idea of updating variables at intermediate stages of the orthogonalization. This technique, applied in partitions identified with known or suspected spectral lines, appears to be especially suited to the analysis of

D. C. Clair; A. K. Rigler

1979-01-01

204

Millimeter-Wave Spectroscopic and Collisional Studies of Molecules and Molecular Ions  

NASA Astrophysics Data System (ADS)

Molecular spectroscopy in the millimeter- and submillimeter-wave regions is an important tool in molecular physics. Information on molecular motions and interactions is obtained from spectroscopic studies of energy levels and collisions. This information and the data from which it is derived are essential in remote sensing of the atmosphere and the interstellar medium. Remote sensing at submillimeter wavelengths is now possible, making higher frequency and quantum number measurements of known interstellar species like water, propionitrile and ethyl alcohol necessary. Remote sensing improvements have also facilitated the need for spectral data on suspected interstellar molecules like propylene. The desire to extract quantitative information from atmospheric remote sensing has resulted in the need for a better understanding of the molecular interactions that cause pressure broadening. The use of a cold molecular ion to magnify the effects of intermolecular interactions has serious implications for pressure broadening theory. The measurement and analysis of rotational spectra of the asymmetric rotors water and propionitrile and the internal rotors propylene and ethyl alcohol are presented. These investigations provide the data and analysis necessary for astronomical observation. The ethyl alcohol investigation is the first experimental millimeter-wave study of a molecule with an asymmetric internal rotor. This study provides the data necessary for detailed theoretical modeling of this type of problem. A novel new experimental technique for generating and studying molecular ions is presented. The first temperature dependent microwave pressure broadening study of a molecular ion colliding with a neutral molecule, HCO^{+} on H_2 , is presented.

Pearson, John Christoffersen

1995-01-01

205

Infrared Spectroscopic Studies with the Stratospheric Observatory for Infrared Astronomy (sofia)  

NASA Astrophysics Data System (ADS)

The joint U.S. and German Stratospheric Observatory for Infrared Astronomy (SOFIA) will be a premier facility for studying the physics and chemistry of the interstellar medium and the stellar evolution process for many decades. SOFIA's first-generation instrument complement includes broadband imagers and moderate resolution spectrographs capable of resolving spectral features due to dust and large molecules, and high resolution spectrometers suitable for kinematic studies of molecular and atomic gas lines at km/s resolution. SOFIA spectroscopic science results from the first flight sequences will be reviewed. We will present plans for future spectroscopic studies.

Gehrz, R. D.; Becklin, E. E.

2012-06-01

206

Spectroscopic Analysis of Sdb Binaries from the Spy Project  

NASA Astrophysics Data System (ADS)

In the course of our search for double degenerate binaries as potential progenitors of type Ia supernovae with the ESO VLT several new subdwarf B (sdB) binaries were discovered. In this paper, we present detailed analysis of six radial velocity variable sdB stars. Radial velocity curves have been measured. From the mass functions we derive lower limits to the masses of the unseen companions and discuss their nature. In addition, effective temperatures, surface gravities, helium abundances and metal abundances were determined.

Karl, C.; Heber, U.; Jeffery, S.; Napiwotzki, R.; Geier, S.

207

Auditory hemodynamic studies of newborn infants using near-infrared spectroscopic imaging  

Microsoft Academic Search

The noninvasive study of tissue blood volume and oxygenation using near-infrared light is a new and actively developing technology. We have used near-infrared spectroscopic imaging (NIRSI) to study hemodynamic responses on the auditory cortices evoked by auditory stimulation. Ten healthy newborn infants were studied. The otoacoustic emission hearing test was performed for each infant. Pulse oximetry was used to monitor

I. Nissila; K. Kotilahti; M. Huotilainen; R. Makela; L. Lipiainen; T. Noponen; N. Gavrielides; R. Naatanen; V. Fellman; T. Katila

2004-01-01

208

An expert system for spectroscopic analysis of rocket engine plumes  

NASA Technical Reports Server (NTRS)

The expert system described in this paper analyzes spectral emissions of rocket engine exhaust plumes and shows major promise for use in engine health diagnostics. Plume emission spectroscopy is an important tool for diagnosing engine anomalies, but it is time-consuming and requires highly skilled personnel. The expert system was created to alleviate such problems. The system accepts a spectral plot in the form of wavelength vs intensity pairs and finds the emission peaks in the spectrum, lists the elemental emitters present in the data and deduces the emitter that produced each peak. The system consists of a conventional language component and a commercially available inference engine that runs on an Apple Macintosh computer. The expert system has undergone limited preliminary testing. It detects elements well and significantly decreases analysis time.

Reese, Greg; Valenti, Elizabeth; Alphonso, Keith; Holladay, Wendy

1991-01-01

209

Spectroscopic Analysis of a LiAg Plasma Plume  

NASA Astrophysics Data System (ADS)

In a series of experiments performed at Sandia National Laboratories to characterize a Li ion source, LiAg plasma plumes were produced by laser ablation of solid targets. Production and detailed characterization of these plasma plumes are also important in laser ablation applications for synthesis of materials. Targets were irradiated with 10 ns FWHM Gaussian pulses from a Nd YAG laser, at fluences of 0.7 J/cm^2. Time- and spatially-resolved optical spectra were recorded with a framing spectrograph using a technique similar to that of microdot spectroscopy. The most prominent lines in the observed spectra include L-shell line emission from Li atoms as well as 5d-5p lines in Ag atoms. The analysis of the spectra is done using a detailed collisional-radiative atomic kinetics model that self-consistently calculates the line emission of Li and Ag atoms. Opacity effects are taken into account using an escape probability approximation, and line shapes are determined by detailed Stark-broadening calculations. This model indicates that line intensity ratios are useful for determining the plasma temperature, while the intensity of forbidden components and line broadening can be used to estimate plasma density. In addition, temperature and density time-histories from hydrodynamic simulations are used in conjunction with time-dependent atomic kinetics to investigate the importance of time-dependent effects in the spectra formation. Analysis of the data permits plasma characterization as a function of time and distance from the surface of the target.

Sherrill, M. E.; Mancini, R. C.; Bailey, J. E.; Filuk, A.; Clark, B.; Lake, P.

1999-11-01

210

Fourier transform infrared spectroscopic analysis of cell differentiation  

NASA Astrophysics Data System (ADS)

Stem cells and its differentiations have got a lot of attentions in regenerative medicine. The process of differentiations, the formation of tissues, has become better understood by the study using a lot of cell types progressively. These studies of cells and tissue dynamics at molecular levels are carried out through various approaches like histochemical methods, application of molecular biology and immunology. However, in case of using regenerative sources (cells, tissues and biomaterials etc.) clinically, they are measured and quality-controlled by non-invasive methods from the view point of safety. Recently, the use of Fourier Transform Infrared spectroscopy (FT-IR) has been used to monitor biochemical changes in cells, and has gained considerable importance. The objective of this study is to establish the infrared spectroscopy of cell differentiation as a quality control of cell sources for regenerative medicine. In the present study, as a basic study, we examined the adipose differentiation kinetics of preadipocyte (3T3-L1) and the osteoblast differentiation kinetics of bone marrow mesenchymal stem cells (Kusa-A1) to analyze the infrared absorption spectra. As a result, we achieved to analyze the adipose differentiation kinetics using the infrared absorption peak at 1739 cm-1 derived from ester bonds of triglyceride and osteoblast differentiation kinetics using the infrared absorption peak at 1030 cm-1 derived from phosphate groups of calcium phosphate.

Ishii, Katsunori; Kimura, Akinori; Kushibiki, Toshihiro; Awazu, Kunio

2007-03-01

211

Molecular and mass spectroscopic analysis of isotopically labeled organic residues  

NASA Technical Reports Server (NTRS)

Experimental studies aimed at understanding the evolution of complex organic molecules on interstellar grains were performed. The photolysis of frozen gas mixtures of various compositions containing H2O, CO, NH3, and CH4 was studied. These species were chosen because of their astrophysical importance as deducted from observational as well as theoretical studies of ice mantles on interstellar grains. These ultraviolet photolyzed ices were warmed up in order to produce refractory organic molecules like the ones formed in molecular clouds when the icy mantles are being irradiated and warmed up either by a nearby stellar source or impulsive heating. The laboratory studies give estimates of the efficiency of production of such organic material under interstellar conditions. It is shown that the gradual carbonization of organic mantles in the diffuse cloud phase leads to higher and higher visual absorptivity - yellow residues become brown in the laboratory. The obtained results can be applied to explaining the organic components of comets and their relevance to the origin of life.

Mendoza-Gomez, Celia X.; Greenberg, J. Mayo; Mccain, P.; Ferris, J. P.; Briggs, R.; Degroot, M. S.; Schutte, Willem A.

1989-01-01

212

Raman spectroscopic analysis of atypical proliferative lesions of the breast  

Microsoft Academic Search

Atypical lesions of the breast have potential to turn malignant. The diagnosis of these lesions has increased considerably with screening mammography. A good understanding of their progression to invasive cancer is yet to be proved. Using Raman spectroscopy to study their chemical finger printing at different stages of proliferation a clear picture of whether a progression exists between lesions could

K. Subramanian; C. Kendall; N. Stone; J. C. Brown; K. McCarthy; J. Bristol; Y. H. Chan

2006-01-01

213

K-? emission spectroscopic analysis from a Cu Z-pinch  

NASA Astrophysics Data System (ADS)

Advances in diagnostic techniques at the Sandia Z-facility have facilitated the production of very detailed spectral data. In particular, data from the copper nested wire-array shot Z1975 provides a wealth of information about the implosion dynamics and ionization history of the pinch. Besides the dominant valence K- and L-shell lines in Z1975 spectra, K-? lines from various ionization stages were also observed. K-shell vacancies can be created from inner-shell excitation and ionization by hot electrons and from photo-ionization by high-energy photons; these vacancies are subsequently filled by Auger decay or resonance fluorescence. The latter process produces the K-? emission. For plasmas in collisional equilibrium, K-? emission usually occurs from highly charged ions due to the high electron temperatures required for appreciable excitation of the K-? transitions. Our simulation of Z1975 was carried out with the NRL 1-D DZAPP non-LTE radiation-hydrodynamics model, and the resulting K- and L-shell synthetic spectra are compared with measured radiation data. Our investigation will focus on K-? generation by both impacting electrons and photons. Synthetic K-? spectra will be generated either by self-consistently calculating the K-shell vacancy production in a full Z-pinch simulation, or by post-processing data from a simulation. The analysis of these K-? lines as well as K- and L-shell emission from valence electrons should provide quantitative information about the dynamics of the pinch plasma.

Dasgupta, A.; Clark, R. W.; Giuliani, J. L.; Ouart, N. D.; Jones, B.; Ampleford, D. J.; Hansen, S. B.

2013-06-01

214

Application of Spectroscopic Methods for Structural Analysis of Chitin and Chitosan  

PubMed Central

Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production. The presence of reactive functional groups as well as the polysaccharide nature of these biopolymers enables them to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for the structural analysis of these compounds.

Kumirska, Jolanta; Czerwicka, Malgorzata; Kaczynski, Zbigniew; Bychowska, Anna; Brzozowski, Krzysztof; Thoming, Jorg; Stepnowski, Piotr

2010-01-01

215

Spectroscopic analysis of diesel combustion flame by means of streak camera  

SciTech Connect

Band spectra in ultraviolet and visible ranges contain information on the state of combustion flame. Measurement of those spectra in diesel combustion flame, however, has been regarded as impossible because of the obstruction of bright flame and soot. The phenomena of diesel combustion, therefore, have not been analyzed clearly from the viewpoint of chemical reaction. The authors inserted an optical fiber into the diesel combustion chamber to detect the flame. The combustion flame was recorded by a special spectroscopic apparatus, named Streak camera, and the recorded image was subjected to spectroscopic analysis. The result of the experiments confirmed the existence of band spectra emitted from CH and OH radicals in the ultraviolet and visible ranges. The recorded data made clear the progress of chemical reactions and the formation of intermediate products during the diesel combustion process.

Nagase, K.; Funatsu, K.

1988-01-01

216

Optical absorption in Ar + irradiated silicon studied through spectroscopic ellipsometry  

NASA Astrophysics Data System (ADS)

The ion implantation induced damage on the optical absorption of band tail states in single crystal Si(1 0 0) have been investigated using a spectroscopic ellipsometer in the energy range 1.7-3.3 eV. The changes induced in the optical absorption coefficient of the material as it undergoes a crystalline to amorphous transformation with increasing fluence, was examined for fluences of Ar + ranging from 6 × 10 13 to 1 × 10 16 ions/cm 2. In the present paper, it is shown that for photon energies higher than the fundamental band gap ( Eg:Si=1.1 eV), the optical absorption follows an exponential behaviour with energy similar to Urbach rule which has hitherto been observed only below Eg. This exponential behaviour of optical absorption between the fundamental edge Eg and the first direct transition ( E1/ E0 critical point CP) at 3.3 eV is characterized by inverse logarithmic slope E01. It is shown that E01 which determines the extent of broadening in the absorption spectra of E1/ E0 CP depends on ion fluence and the underlying microstructure. The increase in broadening is attributed to loss of long range order, introduction of defects, amorphization, changes in microstructure and irradiation induced strain in the material.

Tripura Sundari, S.

2004-01-01

217

Spectroscopic Study of Impurity Behavior in Heliotron-J Plasmas  

SciTech Connect

Behavior of intrinsic and injected impurities has been investigated in Heliotron-J plasmas by spectroscopic methods. Intrinsic impurities are identified with the vacuum ultraviolet grazing incidence spectrometer in neutral beam injection (NBI)-heated plasmas. Na-like Ni XVIII and Mg-like Ni XVIII are observed only in NBI heating phase. Helium gas is injected into electron cyclotron heating plasmas. In the density scan experiments, He II line intensities, which are normalized by the electron density, increase with decreasing electron density. For intrinsic impurities, similar dependence of line intensities on the electron density is observed. The normalized line intensity indicates the particle number of ions penetrated into the core plasma. In addition, the edge electron density is in proportion to the core electron density. These results may reflect the screening effect due to electron collisional ionization at the edge plasma. In the carbon limiter insertion, the CH radical band spectrum is observed. The carbon limiter head is formed in the hemisphere. The spatial distribution of the band emission is asymmetrical to the main axis of the limiter head. A good agreement is obtained between the spatial distribution of emissions of the band spectrum and the camera image with bandpass filter.

Kawazome, Hayato; Tsuboi, Shintaro; Kondo, Katsumi; Mizuuchi, T.; Sano, F.; Nagasaki, K.; Okada, H.; Kobayashi, S.; Takahashi, K.; Shidara, H.; Manabe, Y.; Kaneko, M.; Ohno, Y.; Takamiya, T.; Nishioka, Y.; Yukimoto, H.; Nakazawa, S.; Nishio, S.; Fukagawa, Y.; Yamada, M.; Obiki, T. [Kyoto University (Japan)

2004-07-15

218

Spectroscopic ellipsometry studies of HF treated Si (100) surfaces  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

219

Spectroscopic ellipsometry studies of HF treated Si (100) surfaces  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

220

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)

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.

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

2013-09-01

221

A COMPREHENSIVE SPECTROSCOPIC ANALYSIS OF DB WHITE DWARFS  

SciTech Connect

We present a detailed analysis of 108 helium-line (DB) white dwarfs based on model atmosphere fits to high signal-to-noise optical spectroscopy. We derive a mean mass of 0.67 M{sub sun} for our sample, with a dispersion of only 0.09 M{sub sun}. White dwarfs also showing hydrogen lines, the DBA stars, comprise 44% of our sample, and their mass distribution appears similar to that of DB stars. As in our previous investigation, we find no evidence for the existence of low-mass (M < 0.5 M{sub sun}) DB white dwarfs. We derive a luminosity function based on a subset of DB white dwarfs identified in the Palomar-Green Survey. We show that 20% of all white dwarfs in the temperature range of interest are DB stars, although the fraction drops to half this value above T{sub eff} {approx} 20,000 K. We also show that the persistence of DB stars with no hydrogen features at low temperatures is difficult to reconcile with a scenario involving accretion from the interstellar medium, often invoked to account for the observed hydrogen abundances in DBA stars. We present evidence for the existence of two different evolutionary channels that produce DB white dwarfs: the standard model where DA stars are transformed into DB stars through the convective dilution of a thin hydrogen layer and a second channel where DB stars retain a helium atmosphere throughout their evolution. We finally demonstrate that the instability strip of pulsating V777 Her white dwarfs contains no non-variables, if the hydrogen content of these stars is properly accounted for.

Bergeron, P.; Wesemael, F.; Dufour, Pierre; Beauchamp, A.; Hunter, C.; Gianninas, A.; Limoges, M.-M.; Dufour, Patrick; Fontaine, G. [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada); Saffer, Rex A. [Strayer University, 234 Mall Boulevard, Suite G-50, King of Prussia, PA 19406 (United States); Ruiz, M. T. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Liebert, James, E-mail: bergeron@astro.umontreal.ca, E-mail: wesemael@astro.umontreal.ca, E-mail: gianninas@astro.umontreal.ca, E-mail: limoges@astro.umontreal.ca, E-mail: dufourpa@astro.umontreal.ca, E-mail: fontaine@astro.umontreal.ca, E-mail: alain.beauchamp@fti-ibis.com, E-mail: chris.hunter@yale.edu, E-mail: rex.saffer@strayer.edu, E-mail: mtruiz@das.uchile.cl [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

2011-08-10

222

Raman spectroscopic analysis of combat-related heterotopic ossification development.  

PubMed

Over 60% of our severely combat-injured patient population develops radiographically apparent heterotopic ossification. Nearly a third of these require surgical excision of symptomatic lesions, a procedure that is fraught with complications, and delays or regresses functional rehabilitation in many cases. Unfortunately, for the combat injured, medical contraindications and logistical limitations limit widespread use of conventional means of primary prophylaxis. Better means of risk stratification are needed to both mitigate the risk of current means of primary prophylaxis as well as to evaluate novel preventive strategies currently in development. We asked whether Raman spectral changes, measured ex vivo, correlated with histologic evidence of the earliest signs of HO formation using tissue biopsies from the wounds of combat casualties. In doing so, we compared normal muscle tissue to injured muscle tissue, unmineralized HO tissue, and mineralized HO tissue. The Raman spectra of these tissues demonstrate clear differences in the amide I and amide III spectral regions of HO tissue compared to normal tissue, denoted by changes in the 1640/1445cm(-1)(p<0.01), and 1340/1270cm(-1) (p<0.01) band area ratios (BARs). Additionally, analysis of the bone mineral in HO by Raman spectroscopy appears capable of determining bone maturity by measuring both the 945/960cm(-1) and the 1070/1445cm(-1) BARs. Raman may therefore prove a useful, non-invasive, and early diagnostic modality to detect HO formation prior to it becoming evident clinically or radiographically. This technique could ostensibly be utilized as a non-invasive means to risk stratify individual wounds at a time thought to be amenable to various means of primary prophylaxis. PMID:24012700

Crane, Nicole J; Polfer, Elizabeth; Elster, Eric A; Potter, Benjamin K; Forsberg, Jonathan A

2013-12-01

223

A Comprehensive Spectroscopic Analysis of DB White Dwarfs  

NASA Astrophysics Data System (ADS)

We present a detailed analysis of 108 helium-line (DB) white dwarfs based on model atmosphere fits to high signal-to-noise optical spectroscopy. We derive a mean mass of 0.67 M sun for our sample, with a dispersion of only 0.09 M sun. White dwarfs also showing hydrogen lines, the DBA stars, comprise 44% of our sample, and their mass distribution appears similar to that of DB stars. As in our previous investigation, we find no evidence for the existence of low-mass (M < 0.5 M sun) DB white dwarfs. We derive a luminosity function based on a subset of DB white dwarfs identified in the Palomar-Green Survey. We show that 20% of all white dwarfs in the temperature range of interest are DB stars, although the fraction drops to half this value above T eff ~ 20,000 K. We also show that the persistence of DB stars with no hydrogen features at low temperatures is difficult to reconcile with a scenario involving accretion from the interstellar medium, often invoked to account for the observed hydrogen abundances in DBA stars. We present evidence for the existence of two different evolutionary channels that produce DB white dwarfs: the standard model where DA stars are transformed into DB stars through the convective dilution of a thin hydrogen layer and a second channel where DB stars retain a helium atmosphere throughout their evolution. We finally demonstrate that the instability strip of pulsating V777 Her white dwarfs contains no non-variables, if the hydrogen content of these stars is properly accounted for.

Bergeron, P.; Wesemael, F.; Dufour, Pierre; Beauchamp, A.; Hunter, C.; Saffer, Rex A.; Gianninas, A.; Ruiz, M. T.; Limoges, M.-M.; Dufour, Patrick; Fontaine, G.; Liebert, James

2011-08-01

224

NMR spectroscopic and analytical ultracentrifuge analysis of membrane protein detergent complexes  

PubMed Central

Background Structural studies of integral membrane proteins (IMPs) are hampered by inherent difficulties in their heterologous expression and in the purification of solubilized protein-detergent complexes (PDCs). The choice and concentrations of detergents used in an IMP preparation play a critical role in protein homogeneity and are thus important for successful crystallization. Results Seeking an effective and standardized means applicable to genomic approaches for the characterization of PDCs, we chose 1D-NMR spectroscopic analysis to monitor the detergent content throughout their purification: protein extraction, detergent exchange, and sample concentration. We demonstrate that a single NMR measurement combined with a SDS-PAGE of a detergent extracted sample provides a useful gauge of the detergent's extraction potential for a given protein. Furthermore, careful monitoring of the detergent content during the process of IMP production allows for a high level of reproducibility. We also show that in many cases a simple sedimentation velocity measurement provides sufficient data to estimate both the oligomeric state and the detergent-to-protein ratio in PDCs, as well as to evaluate the homogeneity of the samples prior to crystallization screening. Conclusion The techniques presented here facilitate the screening and selection of the extraction detergent, as well as help to maintain reproducibility in the detergent exchange and PDC concentration procedures. Such reproducibility is particularly important for the optimization of initial crystallization conditions, for which multiple purifications are routinely required.

Maslennikov, Innokentiy; Kefala, Georgia; Johnson, Casey; Riek, Roland; Choe, Senyon; Kwiatkowski, Witek

2007-01-01

225

Spectroscopic analysis of bladder cancer tissues using Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Bladder cancer is one of the most common cancers in Africa. It takes several days to reach a diagnosis using histological examinations of specimens obtained by endoscope, which increases the medical expense. Recently, spectroscopic analysis of bladder cancer tissues has received considerable attention as a diagnosis technique due to its sensitivity to biochemical variations in the samples. This study investigated the use of Fourier transform infrared (FTIR) spectroscopy to analyze a number of bladder cancer tissues. Twenty-two samples were collected from 11 patients diagnosed with bladder cancer from different hospitals without any pretreatment. From each patient two samples were collected, one normal and another cancerous. FTIR spectrometer was used to differentiate between normal and cancerous bladder tissues via changes in spectra of these samples. The investigations detected obvious changes in the bands of proteins (1650, 1550 cm-1), lipids (2925, 2850 cm-1), and nucleic acid (1080, 1236 cm-1). The results show that FTIR spectroscopy is promising as a rapid, accurate, nondestructive, and easy to use alternative method for identification and diagnosis of bladder cancer tissues.

Al-Muslet, Nafie A.; Ali, Essam E.

2012-03-01

226

A Spectroscopic Survey and Analysis of Bright, Hydrogen-rich White Dwarfs  

NASA Astrophysics Data System (ADS)

We have conducted a spectroscopic survey of over 1300 bright (V <= 17.5), hydrogen-rich white dwarfs based largely on the last published version of the McCook & Sion catalog. The complete results from our survey, including the spectroscopic analysis of over 1100 DA white dwarfs, are presented. High signal-to-noise ratio optical spectra were obtained for each star and were subsequently analyzed using our standard spectroscopic technique where the observed Balmer line profiles are compared to synthetic spectra computed from the latest generation of model atmospheres appropriate for these stars. First, we present the spectroscopic content of our sample, which includes many misclassifications as well as several DAB, DAZ, and magnetic white dwarfs. Next, we look at how the new Stark broadening profiles affect the determination of the atmospheric parameters. When necessary, specific models and analysis techniques are used to derive the most accurate atmospheric parameters possible. In particular, we employ M dwarf templates to obtain better estimates of the atmospheric parameters for those white dwarfs that are in DA+dM binary systems. Certain unique white dwarfs and double-degenerate binary systems are also analyzed in greater detail. We then examine the global properties of our sample including the mass distribution and their distribution as a function of temperature. We then proceed to test the accuracy and robustness of our method by comparing our results to those of other surveys such as SPY and Sloan Digital Sky Survey. Finally, we revisit the ZZ Ceti instability strip and examine how the determination of its empirical boundaries is affected by the latest line profile calculations. Based on observations made with ESO Telescopes at the La Silla or Paranal Observatories under program ID 078.D-0824(A).

Gianninas, A.; Bergeron, P.; Ruiz, M. T.

2011-12-01

227

Comparative study of the oxidation of thin porous silicon layers studied by reflectometry, spectroscopic ellipsometry and secondary ion mass spectroscopy  

Microsoft Academic Search

We present a systematic study on ultrathin porous silicon (PS) layers (40–120nm) of different porosities, formed by electrochemical etching and followed by thermal oxidation treatment (300°C and 600°C) and by electrochemical oxidation. The oxidised and non-oxidised PS layers have been analysed by spectroscopic reflectometry (SR), spectroscopic ellipsometry (SE) and secondary ion mass spectroscopy (SIMS). The SR and SE spectra were

M Fried; O Polgár; T Lohner; S Strehlke; C Levy-Clement

1998-01-01

228

Supramolecular spectroscopic and thermal studies of azodye complexes  

NASA Astrophysics Data System (ADS)

A series of heterocyclic ligand of copper(II) complexes have been synthesized by the reaction of copper(II) acetate with 5-(4?-derivatives phenylazo)-2-thioxothiazolidin-4-one (HLn) yields 1:1 and 1:2 (M:L) complexes depending on the reaction conditions. The elemental analysis, spectral (IR and ESR), conductance, magnetic measurements, and thermogravimetric analysis (TGA) are used to characterize the isolated complexes. It is found that the change of substituent affects the thermal properties of azodye rhodanine derivatives and their Cu(II) complexes. The molecular and electronic structures of the investigated compounds (HLn) were also studied using quantum chemical calculations. According to intramolecular hydrogen bond leads to increasing of the complexes stability. The data revealed that the coordination geometry around Cu(II) in all complexes (1-4) exhibit a trans square planar by NO monobasic bidentate and the two monobasic bidentate in octahedral complexes (5-7). Electronic, magnetic data and ESR spectra proposed the square planar structure for all complexes (1-4) under investigation. The value of covalency factor ( and orbital reduction factor K accounts for the covalent nature of the complexes. The activation thermodynamic parameters, such as activation energy (Ea), enthalpy (?H*), entropy (?S*), and Gibbs free energy change of the decomposition (?G*) are calculated using Coats-Redfern and Horowitz-Metzger methods.

El-Sonbati, A. Z.; Diab, M. A.; El-Bindary, A. A.; Morgan, Sh. M.

2014-06-01

229

Spectroscopic Analysis of Flooded Craters from Oceanus Procellarum  

NASA Astrophysics Data System (ADS)

The last major phases of lunar volcanism produced compositionally unique, high-titanium basalts that are not observed elsewhere on the Moon's surface or earlier in its history. These volcanic deposits include some of the Moon's most extensive flows and age estimates suggest that these basalts are among the youngest. These flows are concentrated in Oceanus Procellarum, a very large volcanic province on the lunar near side. Investigations using the Moon Mineralogy Mapper (M3) data have shown that these basalts exhibit strong mineralogical variations, with compositions strongly dominated by either high -Ca pyroxene, or low-Ca pyroxene, or olivine, and even a combination of these minerals. Following the surprising high olivine content of the crater Marius, we examine other flooded craters of the large Oceanus Procellarum (O.P.) province to characterize the uniquess, or not, of Marius. If a large number of flooded craters within O.P. exhibits similar high-olivine content, this will help us to constrain the magmatic history of the last major phases of lunar volcanism. The Moon Mineralogy Mapper (M3) onboard the Indian Space Research Organization's (ISRO) Chandrayaan-1 Spacecraft is an imaging spectrometer that imaged the Moon in 85 spectral channels with a combination of high spectral and spatial mapping, enabling spectra to be placed in a geological context. M3 data have a spectral range from 460 to 3000 nm, and a spectral resolution of 20 to 40 nm. This range allows detailed investigations of the 1 and 2 ?m absorption bands characteristic of mafic minerals on the lunar surface. A selection of flooded craters has been performed to investigate their spectral properties. Craters with unbreached walls have been selected as much as possible in order to better constrain the origin of the volcanic flows. Preliminary results show that few craters share the high-olivine content properties of Marius. Compositionally, crater Billy seems to be the closest one, and to a certain extent the craters Plato, Hansteen and Flamsteed G (although the later one is clearly connected to the surroundings lava flows through its breached walls). More detailed analysis will be performed to highlights the similarities and differences of these flooded craters from a spectral point of view.

Besse, Sebastien; Staid, Matthew; Hiesinger, Harald

2013-04-01

230

An integrated spectroscopic approach for the non-invasive study of modern art materials and techniques  

NASA Astrophysics Data System (ADS)

A non-invasive study has been carried out on 18 paintings by Alberto Burri (1915-1995), one of Italy’s most important contemporary painters. The study aims to demonstrate the appropriate and suitable use of portable non-invasive instrumentation for the characterization of materials and techniques found in works dating from 1948 to 1975 belonging to the Albizzini Collection. Sampling of any kind has been forbidden, in order to maintain the integrity of the paintings. Furthermore, the material heterogeneity of each single artwork could potentially result in a poorly representative sampling campaign. Therefore, a non-invasive and in situ analytical approach has been deemed mandatory, notwithstanding the complexity of modern materials and challenging data interpretation. It is the non-invasive nature of the study that has allowed for the acquisition of vast spectral data (a total of about 650 spectra including XRF, mid and near FTIR, micro-Raman and UV-vis absorption and emission spectroscopies). In order to better handle and to extrapolate the most meaningful information from these data, a statistical multivariate analysis, namely principal component analysis (PCA), has been applied to the spectral results. In particular, the possibility of combining elemental and molecular information has been explored by uniting XRF and infrared spectra in one PCA dataset. The combination of complementary spectroscopic techniques has allowed for the characterization of both inorganic and organic pigments, extenders, fillers, and binders employed by Alberto Burri.

Rosi, F.; Miliani, C.; Clementi, C.; Kahrim, K.; Presciutti, F.; Vagnini, M.; Manuali, V.; Daveri, A.; Cartechini, L.; Brunetti, B. G.; Sgamellotti, A.

2010-09-01

231

A study of non-Keplerian velocities in observations of spectroscopic binary stars  

NASA Astrophysics Data System (ADS)

This paper presents an orbital analysis of six southern single-lined spectroscopic binary systems. The systems selected were shown to have circular or nearly circular orbits (e < 0.1) from earlier published solutions of only moderate precision. The purpose was to obtain high-precision orbital solutions in order to investigate the presence of small non-Keplerian velocity effects in the data and hence the reality of the small eccentricities found for most of the stars. The Hercules spectrograph and 1-m McLellan telescope at Mt John Observatory, New Zealand, were used to obtain over 450 CCD spectra between 2004 October and 2007 August. Radial velocities were obtained by cross-correlation. These data were used to achieve high-precision orbital solutions for all the systems studied, sometimes with solutions up to about 50 times more precise than those from the earlier literature. However, the precision of the solutions is limited in some cases by the rotational velocity or chromospheric activity of the stars. The data for the six binaries analysed here are combined with those for six stars analysed earlier by Komonjinda, Hearnshaw and Ramm. We have performed tests using the prescription of Lucy on all 12 binaries, and conclude that, with one exception, none of the small eccentricities found by fitting Keplerian orbits to the radial-velocity data can be supported. Instead we conclude that small non-Keplerian effects, which are clearly detectable for six of our stars, make impossible the precise determination of spectroscopic binary orbital eccentricities for many late-type stars to better than about 0.03 in eccentricity, unless the systematic perturbations are also carefully modelled. The magnitudes of the non-Keplerian velocity variations are given quantitatively.

Hearnshaw, J. B.; Komonjinda, Siramas; Skuljan, J.; Kilmartin, P. M.

2012-11-01

232

Mechanism of Arsenic Adsorption Using Wheat Biomass -- a spectroscopic study  

NASA Astrophysics Data System (ADS)

Arsenic is a trace element that is toxic to animals, humans included. Since the current Environmental Protection Agency guidelines regarding water quality standards indicate that arsenic concentrations in excess of 50 ppb are hazardous to welfare of humans, the search for new water remediation methods or improvements of previous methods have been a focus in environmental technology. Investigations of arsenic uptake have used wide range of sorbents including iron oxides and oxyhydroxides, for which it have been proved that arsenic shows high affinity. In this study, we used far-infrared spectroscopy to examine the arsenic reduction using biomaterials. pH dependence analysis by FTIR demonstrates the sorption of iron oxides and oxyhydroxides by the wheat biomass. The splitting of 350 cm-1 amorphous iron oxide vibrations is a direct proof of the arsenic uptake. In addition, there is evidence of sorption of arsenic at sulfhydryl group of cysteine existent in wheat.

Calvo, Oscar; Manciu, Felicia; Maldonado, Josefina; Gardea-Torresdey, Jorge

2006-10-01

233

In-beam spectroscopic studies of the 44S nucleus  

NASA Astrophysics Data System (ADS)

The structure of the 44S nucleus has been studied at GANIL through the one proton knock-out reaction from a 45Cl secondary beam at 42 A·MeV. The ? rays following the de-excitation of 44S were detected in flight using the 70 BaF2 detectors of the Château de Cristal array. An exhaustive ??-coincidence analysis allowed an unambiguous construction of the level scheme up to an excitation energy of 3301 keV. The existence of the spherical 22+ state is confirmed and three new ?-ray transitions connecting the prolate deformed 21+ level were observed. Comparison of the experimental results to shell model calculations further supports a prolate and spherical shape coexistence with a large mixing of states built on the ground state band in 44S.

Cáceres, L.; Sohler, D.; Grévy, S.; Sorlin, O.; Dombrádi, Zs.; Bastin, B.; Achouri, N. L.; Angélique, J. C.; Azaiez, F.; Baiborodin, D.; Borcea, R.; Bourgeois, C.; Buta, A.; Bürger, A.; Chapman, R.; Dalouzy, J. C.; Dlouhy, Z.; Drouard, A.; Elekes, Z.; Franchoo, S.; Gaudefroy, L.; Iacob, S.; Laurent, B.; Lazar, M.; Liang, X.; Liénard, E.; Mrazek, J.; Nalpas, L.; Negoita, F.; Nowacki, F.; Orr, N. A.; Penionzhkevich, Y.; Podolyák, Zs.; Pougheon, F.; Poves, A.; Roussel-Chomaz, P.; Saint-Laurent, M. G.; Stanoiu, M.; Stefan, I.

2012-02-01

234

[Structural characterization and spectroscopic analysis of the aloin].  

PubMed

Aloe is widely used in various fields for its rich polysaccharides, proteins, amino acids, vitamins, active enzymes and trace beneficial elements to human body. However, the main active ingredient aloin is also an allergenic ingredient, which even may cause a severe allergic reaction In this study, infrared spectroscopy, Raman spectroscopy applied to the structural characterization of the aloin Density functional theory (DFT) is applied to the theoretical calculations using the B3LYP/6-31G (d) basis set vibration, which was helpful to understand the aloin molecular vibrational frequency. By comparing we choose the optimal experimental condition for water as solvent under alkaline conditions, the detection limit of the Aloin can reach a level of 5 ppm, which can be considered the theoretical basis for rapid detection of aloin content. PMID:24822406

Xie, Yun-Fei; Huan, Nan; Cao, Yuan-Yuan; Wang, He-Ya; Zhong, Ying; Yao, Wei-Rong; Qian, He

2014-02-01

235

Multiple-perturbation two-dimensional (2D) correlation analysis for spectroscopic imaging data  

NASA Astrophysics Data System (ADS)

A series of data analysis techniques, including multiple-perturbation two-dimensional (2D) correlation spectroscopy and kernel analysis, were used to demonstrate how these techniques can sort out convoluted information content underlying spectroscopic imaging data. A set of Raman spectra of polymer blends consisting of poly(methyl methacrylate) (PMMA) and polyethylene glycol (PEG) were collected under varying spatial coordinates and subjected to multiple-perturbation 2D correlation analysis and kernel analysis by using the coordinates as perturbation variables. Cross-peaks appearing in asynchronous correlation spectra indicated that the change in the spectral intensity of the free Cdbnd O band of the PMMA band occurs before that of the Cdbnd O⋯Hsbnd O band arising from the molecular interaction between PMMA and PEG. Kernel matrices, generated by carrying out 2D correlation analysis on principal component analysis (PCA) score images, revealed subtle but important discrepancy between the patterns of the images, providing additional interpretation to the PCA in an intuitively understandable manner. Consequently, the results provided apparent spectroscopic evidence that PMMA and PEG in the blends are partially miscible at the molecular level, allowing the PMMAs to respond to the perturbations in different manner.

Shinzawa, Hideyuki; Hashimoto, Kosuke; Sato, Hidetoshi; Kanematsu, Wataru; Noda, Isao

2014-07-01

236

Spectroscopic analysis of global tide gauge sea level data  

NASA Technical Reports Server (NTRS)

Yearly and monthly global tide-gage sea-level data are fitted to numerically generated tidal data in order to search for the 18.6-yr lunar nodal tide and 14-month pole tide. Both of these tides are clearly evident, with amplitudes and phases that are consistent with a global equilibrium response. The ocean's response to atmospheric pressure is studied with the least-squares fit technique. Consideration is given to the global rise in sea level, the effects of postglacial rebound, and the possible causes of the enhanced pole tides in the North Sea, the Baltic Sea, and the Gulf of Bothnia. The results support O'Connor's (1986) suggestion that the enhanced pole tide in these regions is due to meteorological forcing rather than a basin-scale resonance. Also, the global average of the tide-gage data show an increase in sea level over tha last 80 yr of between 1.1 and 1.9 mm/yr.

Trupin, A.; Wahr, J.

1990-01-01

237

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

PubMed

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. PMID:23697107

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

2013-02-01

238

Raman spectroscopic study of Lactarius spores (Russulales, Fungi)  

NASA Astrophysics Data System (ADS)

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.

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

2005-10-01

239

A Spectroscopic Analysis of Blue Stragglers, Horizontal Branch Stars, and Turnoff Stars in Four Globular Clusters  

NASA Astrophysics Data System (ADS)

We present a spectroscopic analysis of HST STIS and FOS low- and intermediate-resolution spectroscopy of 55 stars in four globular clusters (47 Tucanae, M3, NGC 6752, and NGC 6397). Stars hotter than Teff=5750 K and with a signal-to-noise ratio larger than 15 were analyzed with non-local thermodynamic equilibrium model atmospheres, and values for their effective temperatures and gravities were obtained. Using photometric fluxes, we also obtained radii, luminosities, and spectroscopic masses. Twenty-four stars in our sample are blue stragglers (BSs). Their photometric colors and magnitudes place these BSs above and redward of the clusters' zero-age main sequence: this is consistent with the gravities we find for these stars, which are lower than zero-age main-sequence gravities. A comparison with stellar evolutionary tracks shows that almost all of our BSs are in the Hertzsprung gap. This is contrary to theory, because of the short timescale expected for stars in this evolutionary phase. The mean BS mass is 1.04 Msolar for 14 nonvariable stars, or 1.07 Msolar counting all 24 BSs in our sample. For the nonvariable stars the mean BS masses for individual clusters are 1.73, 1.01, 0.95, and 0.72 Msolar for NGC 6397, NGC 6752, 47 Tuc, and M3, respectively. Adding the variable stars (which improves the statistics but increases the uncertainty), the mean masses become 1.27, 1.05, 0.99, and 0.99 Msolar, respectively. Although there is considerable scatter, the BS spectroscopic masses correlate with both effective temperature and brightness of the stars, as expected. The mean nonvariable turnoff star mass (0.58 Msolar) is significantly below the values determined for the BSs and below the main-sequence turnoff mass. The mean nonvariable horizontal-branch (HB) star mass is higher than expected (0.79 Msolar). In particular, several HB stars have masses well above the main-sequence turnoff mass. Some of these HB stars are suspected of actually being BSs, since most of them reside at ambiguous locations on the CMD, making them prone to misclassification. Values and limits to the stellar rotation rates (vsini) are imposed by fitting weak metal lines, the Ca II K line wings, or the helium lines for the hotter stars. Five BSs with reasonably constrained rotations show average and median vsini values of 109 and 100 km s-1, respectively, suggesting v~160 km s-1. At least some GC BSs are very rapid rotators, but this information cannot yet constrain their origin as stellar collision or binary mergers because of the lack of clear theoretical predictions. Six extreme HB stars have rotation rates vsini between 50 and 200 km s-1, which are high for these stars and might indicate a binary origin. De Marco et al. found that four BSs and two HB stars in our sample have Balmer jumps that are too large for the effective temperatures implied by the slopes of their Paschen continua. Two additional HB stars are now identified in the current study as having the same feature. For these stars, the presence of a disk of partly ionized material is suspected, although high stellar rotation rates could also partly explain the data.

De Marco, Orsola; Shara, Michael M.; Zurek, D.; Ouellette, John A.; Lanz, Thierry; Saffer, Rex A.; Sepinsky, Jeremy F.

2005-10-01

240

A theoretical and spectroscopic study of conformational structures of piroxicam  

NASA Astrophysics Data System (ADS)

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.

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

2010-02-01

241

Spectroscopic study on binding of rutin to human serum albumin  

NASA Astrophysics Data System (ADS)

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.

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

2007-10-01

242

Raman spectroscopic studies of carbon in extra-terrestrial materials  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

243

Vibrational spectroscopic studies of Isoleucine by quantum chemical calculations.  

PubMed

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. PMID:24508874

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

2014-04-24

244

Structural studies of oxalohydroxamic acid by single crystal X-ray diffraction and spectroscopic methods  

Microsoft Academic Search

The structure of oxalohydroxamic acid has been investigated by X-ray and spectroscopic analyses. It has been shown that oxalohydroxamic acid exists in the oxamic form in the solid as well as in solution. The variable-temperature nuclear magnetic resonance (NMR) studies reveal an exchange of OH and NH protons, the exchange being faster at higher temperatures. The kinetic and the thermodynamic

A. Sameena Begum; V. K. Jain; C. L. Khetrapal; N. C. Shivaprakash

1987-01-01

245

Spectroscopic studies in protein films with highly sensitive single-mode guided-wave plataforms  

Microsoft Academic Search

In this work we report experimental results on the molar absorptivity of cytochrome c adsorbed at different submonolayer levels onto an aluminum oxide waveguide surface. The spectra was acquired using the broadband, single-mode, integrated optical waveguide spectroscopic technique, which is an extremely sensitive tool able to reach submonolayer levels of detection required for this type of studies. For a protein

Rodrigo S. Wiederkehr; Geoffrey C. Hoops; Mustafa M. Aslan; Courtney L. Byard; Sergio B. Mendes

2009-01-01

246

Spectroscopic studies of H-decorated interstitials and vacancies in thin-film silicon exfoliation  

Microsoft Academic Search

In this paper, we review the pivotal role that defects (in particular vacancy structures) play in driving the H-induced exfoliation of Si. We highlight the central role that infrared spectroscopy has played in delineating the microscopic details of the exfoliation process. We show that when the results of such spectroscopic studies are combined with those obtained using a variety of

Y. J Chabal; M. K Weldon; Y. Caudano; B. B. Stefanov; K. Raghavachari

1999-01-01

247

Fourier Transform Raman Spectroscopic Study of a Poly (propylene oxide)-Based Model Network Electrolyte.  

National Technical Information Service (NTIS)

Raman spectroscopic studies of the model network derived from poly(propylene oxide) with tris(4-isocyanatophenyl) thiophosphate (triisocyanate) in the presence of salt, LiClO4, have been carried out over a range of salt concentrations and molecular weight...

S. Yoon K. Ichikawa W. J. MacKnight S. L. Hsu

1995-01-01

248

Calorimetric and spectroscopic studies on the interaction of anticancer drug mitoxantrone with human serum albumin  

Microsoft Academic Search

Binding of the anticancer drug mitoxantrone with the protein human serum albumin (HSA) has been studied by using isothermal titration calorimetry (ITC), in combination with fluorescence, UV–visible, and circular dichroism spectroscopy. The thermodynamic parameters of binding have been evaluated from ITC and spectroscopic results and compared. The ITC results demonstrate that the binding of mitoxantrone with HSA occurs according to

Neelam Keswani; Nand Kishore

2011-01-01

249

Laser apparatus and method for microscopic and spectroscopic analysis and processing of biological cells  

DOEpatents

An apparatus and method are disclosed for microscopic and spectroscopic analysis and processing of biological cells. The apparatus comprises a laser having an analysis region within the laser cavity for containing one or more biological cells to be analyzed. The presence of a cell within the analysis region in superposition with an activated portion of a gain medium of the laser acts to encode information about the cell upon the laser beam, the cell information being recoverable by an analysis means that preferably includes an array photodetector such as a CCD camera and a spectrometer. The apparatus and method may be used to analyze biomedical cells including blood cells and the like, and may include processing means for manipulating, sorting, or eradicating cells after analysis. 20 figs.

Gourley, P.L.; Gourley, M.F.

1997-03-04

250

Laser apparatus and method for microscopic and spectroscopic analysis and processing of biological cells  

DOEpatents

An apparatus and method for microscopic and spectroscopic analysis and processing of biological cells. The apparatus comprises a laser having an analysis region within the laser cavity for containing one or more biological cells to be analyzed. The presence of a cell within the analysis region in superposition with an activated portion of a gain medium of the laser acts to encode information about the cell upon the laser beam, the cell information being recoverable by an analysis means that preferably includes an array photodetector such as a CCD camera and a spectrometer. The apparatus and method may be used to analyze biomedical cells including blood cells and the like, and may include processing means for manipulating, sorting, or eradicating cells after analysis thereof.

Gourley, Paul L. (12508 Loyola, NE., Albuquerque, NM 87112) [12508 Loyola, NE., Albuquerque, NM 87112; Gourley, Mark F. (7509 Spring Lake Dr., Apt. B1, Bethesda, MD 20817) [7509 Spring Lake Dr., Apt. B1, Bethesda, MD 20817

1997-01-01

251

Raman spectroscopic mapping for the analysis of solar radiation induced skin damage.  

PubMed

The effects of simulated solar irradiation of an artificial skin model have been examined using Raman spectroscopy and the results are compared with cytotoxicological and histological profiling. Samples exposed for times varying between 30 minutes and 240 minutes were incubated post exposure for a period of 96 hours. The cytotoxicological response as measured by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay demonstrated a ~50% loss of viability of the artificial tissue after 120 minutes exposure. Histological staining of tissue sections showed considerable loss of cellular content in the epidermal layer at this endpoint. Raman spectroscopic mapping of tissue sections, coupled with K-means cluster analysis (KMCA) clearly identified the dermal and stratum corneum layers and differentiated further substructures of the epidermis. Post irradiation, a significant loss of DNA features in the basal layer was apparent in the results of the KMCA. Principal Components Analysis (PCA) of layers identified by the KMCA post exposure compared with controls indicated a significant increase in the lipidic signatures of the stratum corneum. In the dermal layer, little photodamage was observed, but a similar increase in lipidic signatures in the basal layer was accompanied by a decrease in DNA and protein contributions. The spectral profiles of the photodamage to the basal layer as identified by PCA are consistent over the exposure periods of 30-240 minutes, but an examination of the evolution of features associated with specific biochemical components indicated DNA damage and loss of lipidic signatures at the early exposure times, whereas changes in protein signatures appeared to evolve over longer periods. In comparison to the cytotoxicological responses, the study demonstrates that Raman spectroscopy can identify biochemical changes as a result of solar exposure at time points significantly earlier than changes in tissue viability are observed. PMID:23471356

Ali, S M; Bonnier, F; Ptasinski, K; Lambkin, H; Flynn, K; Lyng, F M; Byrne, H J

2013-07-21

252

Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base  

NASA Astrophysics Data System (ADS)

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(?-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).

Abu Al-Nasr, Ahmad K.; Ramadan, Ramadan M.

2013-03-01

253

Spectroscopic study of sigma Geminorum from IUE (Ekmekci+, 2002)  

NASA Astrophysics Data System (ADS)

The IUE spectra of ? Gem have been taken from the NASA IUE archive using IDL (Interactive Data Language). The spectra have been observed in 1979-1986 period. All the spectra analysed in the present study have NEWSIPS reductions and consist of 25 LWP, 8 LWR and 5 SWP images in high resolution, and 2 LWP and 14 SWP images in low dispersion. The emission lines, identified as activity indicators and originating in the chromosphere and transition region, are seen in the spectra. The emission line fluxes and equivalent widths are computed based on Gaussian profile fitting procedures to examine the existence of any line flux variation that depends on time or orbital phase. It was found that there is a flux variation with time and orbital phase that is in good agreement with the photometric light curve variation. By comparing the flux variation with simultaneous light curve variation, it can be shown that there is a relation between the ultraviolet flux variation and the spot activity of the system, as shown by Ayres et al. (1984ApJ...279..197A) and Engvold et al. (1988A&A...192..234E) based on their IUE (with IUESIPS reduction) spectral analysis. Moreover, it was inferred that there is no ultraviolet excess in ? Gem by comparing the spectra of ? Gem taken as a comparison star. The Mg II h and k radial velocity curves of ? Gem were in a good agreement with data obtained by Eker (1986MNRAS.221..947E) and Duemmler et al. (1997A&AS..123..209D). (4 data files).

Ekmekci, F.; Karakus, O.

2002-08-01

254

Spectroscopic and electrochemical studies of electrochromic hydrated nickel oxide films  

SciTech Connect

The electrochromic properties of hydrated nickel oxide thin films electrochemically deposited by anodization onto doped tin oxide-coated glass have been studied by transmittance measurements, cyclic voltammetry, Fourier-transform infrared spectroscopy, and ion-backscattering spectrometry. The spectral transmittance is reported for films switched in both the bleached and colored states. The photopic transmittance (T/sub p/) can be switched from T/sub p/(bleached) = 0.77 to T/sub p/(colored) = 0.21, and the solar transmittance (T/sub S/) can be switched from T/sub S/(bleached) = 0.73 to T/sub S/(colored = 0.35. Also reported is the near-infrared transmittance (T/sub NIR/), which was found to switch from T/sub NIR/(bleached) = 0.72 to T/sub NIR/(colored) = 0.55 for a film thickness of 500 A. The bleached condition is noted to have very low solar absorption in both the visible and solar regions. Ion-backscattering spectrometry was performed on the hydrated nickel oxide film, yielding a composition of NiO/sub 1.0/ (dehydrated). Cyclic voltammetry showed that, for films in the bleached or colored state, the reversible reaction is Ni(OH)/sub 2/ ..-->.. NiOOH + H/sup +/ + e/sup -/. Voltammetry also showed that the switching of the film is controlled by the diffusion of protons, where OH/sup -/ plays a role in the reaction mechanism. Analysis of the hydrated nickel-oxide thin films by Fourier-transform infrared spectroscopy revealed that both the bleached and colored states contain lattice water and hydroxyl groups. The surface hydroxyl groups play an important role in the coloration and bleaching of the anodically deposited nickel oxide thin films.

Yu, P.C.; Nazri, G.; Lampert, C.M.

1986-07-01

255

Solvated Crystalline Forms of Nevirapine: Thermoanalytical and Spectroscopic Studies  

PubMed Central

The study is aimed at exploring the utility of thermoanalytical methods in the solid-state characterization of various crystalline forms of nevirapine. The different forms obtained by recrystallization of nevirapine from various solvents were identified using differential scanning calorimetry and thermogravimetric analysis (TGA). The appearance of desolvation peak accompanied by weight loss in TGA indicated the formation of solvates: hemi-ethanolate (Form I), hemi-acetonitrilate (Form II), hemi-chloroformate (Form III), hemi-THF solvate (Form IV), mixed hemi-ethanolate hemi-hydrate (Form V), and hemi-toluenate (Form VI). The higher desolvation temperatures of all the solvates except toluenate than their respective boiling point indicate tighter binding of solvent. Emphasis has been laid on the determination of heat capacity and heat of solution utilizing microreaction calorimeter to further distinguish the various forms. The enthalpy of solution (?Hsol), an indirect measure of the lattice energy of a solid, was well correlated with the crystallinity of all the solid forms obtained. The magnitude of ?Hsol was found to be ?14.14 kJ/mol for Form I and ?2.83 kJ/mol for Form V in phosphate buffer of pH 2, exhibiting maximum ease of molecular release from the lattice in Form I. The heat capacity for solvation (?Cp) was found to be positive, providing information about the state of solvent molecules in the host lattice. The solubility and dissolution rate of the forms were also found to be in agreement with their enthalpy of solution. Form (I), being the most exothermic, was found to be the most soluble of all the forms.

Arora, Poonam; Saini, Anupam; Jain, Dharamvir Singh

2010-01-01

256

Spectroscopic studies of the progress of humification processes in humic acid extracted from sewage sludge  

NASA Astrophysics Data System (ADS)

The humic acids extracted from sludge collected from the digestion chamber and the sludge drying beds were studied. The sludge samples were collected, dried and humic acids were extracted. The progress of the humification processes was studied with EPR, IR and NMR spectroscopic methods. For extracted humic acids, concentration of free radicals and g factor was determined with EPR. The presence of characteristic functional groups was confirmed with IR and NMR spectroscopy. To study the changes in content of the elements, the elemental analysis was performed to determine the percentage of carbon, hydrogen, nitrogen, sulfur and oxygen. Taking all the obtained results into account it was found that on the sewage drying beds, humification processes take place in the sludge. In the first two weeks when the sludge on the drying beds an intensive enrichment of humic acids in free radicals takes place. This is the result of the intensive humification process course after the stage in the fermentation chamber where the mesophilic fermentation takes place. Moreover, the humidity of sludge influences the intensive development of free radical concentration at the beginning of the storing period, whereas the humification processes still continue.

Polak, J.; Su?kowski, W. W.; Bartoszek, M.; Papie?, W.

2005-06-01

257

A spectroscopic study of field BHB star candidates  

NASA Astrophysics Data System (ADS)

New spectroscopic observations are presented for a sample of thirty-one blue horizontal branch (BHB) star candidates that are sufficiently nearby to have reliable proper motions. Comments are given on a further twenty-five stars that have previously been suggested as BHB star candidates but which were not included in our sample. Moderately high-resolution spectra (lambda /Delta lambda ~ 15 000) of twenty five of our program stars were taken with the coudé feed spectrograph at Kitt Peak. Twelve of the program stars were also observed with the CAT spectrograph at ESO. Six of these program stars were observed from both hemispheres. IUE low-resolution spectra are available for most of our candidates and were used, in addition to other methods, in the determination of their Teff and reddening. A compilation of the visual photometry for these stars (including new photometry obtained at Kitt Peak) is also given. Abundances were obtained from these spectra using models computed by Castelli with an updated version of the ATLAS9 code (Kurucz 1993a). All thirty one candidates are halo stars. Of these, twenty eight are classified as BHB stars because: [(1)]they lie close to the ZAHB (in a similar position to the BHB stars in globular clusters) in the Teff versus log g plot. For all but one of these stars, far-UV data were available which were consistent with other data (Strömgren photometry, energy distributions, H? profiles) for deriving Teff and log g. [(2)]they have a distribution of km s-1i (<=40 km s-1) that is similar to that found for the BHB in globular clusters. Peterson et al. (1995) and Cohen & McCarthy (1997) have shown that the BHB stars in the globular clusters M13 and M92 have a higher km s-1i (<= 40 km s-1) than those in M3 and NGC 288 (<=20 km s-1). The mean deprojected rotational velocity (/line{v}) was calculated for both the two globular clusters and the nearby BHB star samples. A comparison of these suggests that both globular cluster km s-1i types are present in our nearby sample. No obvious trend is seen between km s-1i and either (B-V)o or [Fe/H]. [(3)]they have -0.99>=[Fe/H]>=-2.95 (mean [Fe/H] -1.67; dispersion 0.42 dex), which is similar to that found for field halo RR Lyrae and red HB stars. These local halo field stars appear (on average) to be more metal-poor than the halo globular clusters. The local sample of red giant stars given by Chiba & Yoshii (1998) contains a greater fraction of metal-poor stars than either our halo samples or the halo globular clusters. The stars in our sample that have a Teff that exceeds about 8 500 K show the He i (lambda 4471) line with a strength that corresponds to the solar helium abundance. [(4)]they show a similar enhancement of the alpha -elements (< [Mg/Fe]right > = +0.43+/-0.04 and also < [Ti/Fe]right > = +0.44+/-0.02) to that found for other halo field stars of similar metallicity. Based on observations obtained at KPNO, operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation, and the European Southern Observatory, Chile. Tables 4 and 5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr

Kinman, T.; Castelli, F.; Cacciari, C.; Bragaglia, A.; Harmer, D.; Valdes, F.

2000-12-01

258

Vibrational and impedance spectroscopic studies on lithium vanadate prepared by solid-state reaction  

Microsoft Academic Search

The lithium vanadate (LiV2O5) has been prepared by solid-state reaction method. The Laser Raman and FTIR spectroscopic analysis have been carried which reveal the presence of multiphase lithium vanadium oxides. The ?-phase of LiV2O5 has been detected by the presence of Raman peaks at 960 and 942 cm?1. The ?- and ?-phases of lithium vanadate have been confirmed by the

M Vijayakumar; S Selvasekarapandian; R Kesavamoorthy; Koichi Nakamura; Tatsuo Kanashiro

2003-01-01

259

First Spectroscopic Study in the Near-Infrared (NIR) of Self-Forming Nano Vesicles  

Microsoft Academic Search

In this work, we present the first spectroscopic data in the near-infrared (NIR) for synthetic nano vesicles in the spectral range of 11000-4700 cm-1. I n addition, we have established specific band structures as molecular fingerprints corresponding to overtones and combinations vibrational modes involving C-H, O-H and N-H functional groups for sample analysis of QuS omes™. In particular, we have

R. Bista; A. Akambi; A. Ambardekar; R. Bruch; B. Keller

2007-01-01

260

Analysis of heavy metals during composting of the tannery sludge using physicochemical and spectroscopic techniques.  

PubMed

The major limitation of direct application of tannery sludge compost in agriculture is the total heavy metal contents and their bioavailability to the soil-plant system. This study focused on the heavy metal characterization and the influence of changing the physicochemical properties of the medium throughout the composting on the concentrations, bioavailability or chemical forms of Cr, Cu, Zn, Pb and Cd in tannery sludge. The study shows that throughout the 60 days of composting, physicochemical analysis and Fourier-transformed infrared (FTIR) spectroscopic characterization show that all parameters elaborated and reached relatively stable levels reflecting the stability and maturity of the final product, and revealed the biodegradation of components that can be easily assimilated by microorganism. The C/N ratio reaches the optimal range of stable compost; inorganic nitrogen is transformed into stable organic forms. The total concentration of Cr, Zn, Cu, Pb and Cd is very low rendering final compost acceptable for agricultural use. The germination index for both Chinese cabbage and lettuce was 97% after 60 days of composting, showing that the final compost was not phytotoxic. Furthermore, in using a sequential extraction method in sludge compost at different phases of treatment, a less than 2% of metals bound to bioavailable fractions X-(KNO(3)+H(2)O). A large proportion of the heavy metals were associated to the residual fraction (75-85%) and more resistant fractions to extraction X-NaOH, X-EDTA, X-HNO(3) (15-25%). Mobile fractions of metals are poorly predictable from the total content. Bioavailability of all fractions of elements tends to decrease. PMID:18990495

Haroun, Mahdi; Idris, Azni; Omar, Syed

2009-06-15

261

Nucleation and growth of MgO atomic layer deposition: A real-time spectroscopic ellipsometry study  

SciTech Connect

The atomic layer deposition (ALD) of MgO thin films from bis(cyclopentadienyl) magnesium and H{sub 2}O was studied using in-situ real-time spectroscopic ellipsometry (SE), ex-situ x-ray photoelectron spectroscopy, and grazing-incidence x-ray diffraction. It is found that the initial growth is not linear during the first ten cycles, and magnesium silicate forms spontaneously on the SiO{sub 2}/Si substrates at 250 °C. Submonolayer sensitivity of SE is demonstrated by the analysis of each half-cycle and self-limiting adsorption, revealing characteristic features of hetero- and homo-MgO ALD processes.

Wang, Han; Fu, Kan [Department of Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269. (United States)] [Department of Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269. (United States)

2013-11-15

262

Near infrared spectroscopic analysis of single malt Scotch whisky on an optofluidic chip.  

PubMed

Standardization and quality monitoring of alcoholic beverages is an important issue in the liquor production industry. Various spectroscopic techniques have proved useful for tackling this problem. An ideal sensing device for alcoholic beverages should be able to detect the quality of alcohol with a small amount of sample at a low acquisition time using a portable and easy to use device. We propose the use of near infra-red spectroscopy on an optofluidic chip for quality monitoring of single malt Scotch whisky. This is chip upon which we have previously realized waveguide confined Raman spectroscopy. Analysis on this alignment-free, portable chip may be performed in only 2 seconds with a sample volume of only 20 µl. Using a partial least square (PLS) calibration, we demonstrate that the alcohol content in the beverage may be predicted to within a 1% prediction error. Principal component analysis (PCA) was employed for successful classification of whiskies based upon their age, type and cask. The prospect of implementing an optofluidic analogue of a conventional fiber based spectroscopic probe allows a rapid analysis of alcoholic beverages with dramatically reduced sample volumes. PMID:22109177

Ashok, Praveen C; Praveen, Bavishna B; Dholakia, K

2011-11-01

263

Interaction of an anthracycline disaccharide with ctDNA: Investigation by spectroscopic technique and modeling studies  

NASA Astrophysics Data System (ADS)

This study was designed to examine the interaction of an anthracycline disaccharide, 4'- O-(?-L-oleandrosyl) daunorubicin (DNR-D2), with calf thymus deoxyribonucleic acid (ctDNA) by UV-vis in combination with fluorescence spectroscopy and molecular modeling techniques under physiological conditions (Britton-Robinson buffer solutions, pH 7.4). By the analysis of UV-vis and fluorescence spectrum, it was observed that the binding mode between DNR-D2 and ctDNA might be intercalation, and fluorescence quenching mechanism of DNR-D2 by ctDNA was a static quenching type. Upon binding to ctDNA, the anthraquinone chromophore of DNR-D2 could slide into the C-G rich region of ctDNA. Hydrogen bonding forces may play an essential role in the binding of DNR-D2 to ctDNA. Furthermore, the results obtained from computational modeling corroborated the experimental results obtained from spectroscopic investigations. These studies are valuable for a better understanding the datailed mode of DNR-D2-DNA interaction, which should be important in deeper insight into the therapeutic efficiency of DNR-D2.

Lu, Yan; Lv, Juan; Zhang, Guisheng; Wang, Gongke; Liu, Qingfeng

2010-05-01

264

Studies on the inclusion behavior of 9-Aminoacridine into cyclodextrins: spectroscopic and theoretical evidences.  

PubMed

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 (?-CD and ?-CD) has been studied using UV-Vis absorption, steady state time resolved fluorescence, (1)H NMR and FT-IR spectroscopy techniques. The spectroscopic measurements show that 9-AA does not form stable complex with ?-CD and also confirmed by DFT calculations. On the other hand, 9-AA forms inclusion complex with ?-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. PMID:23257326

Manivannan, C; Vijay Solomon, R; Venuvanalingam, P; Renganathan, R

2013-02-15

265

Studies on the inclusion behavior of 9-Aminoacridine into cyclodextrins: Spectroscopic and theoretical evidences  

NASA Astrophysics Data System (ADS)

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 (?-CD and ?-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 ?-CD and also confirmed by DFT calculations. On the other hand, 9-AA forms inclusion complex with ?-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.

Manivannan, C.; Vijay Solomon, R.; Venuvanalingam, P.; Renganathan, R.

2013-02-01

266

Optical and spectroscopic studies on tannery wastes as a possible source of organic semiconductors  

NASA Astrophysics Data System (ADS)

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.

Nashy, El-Shahat H. A.; Al-Ashkar, Emad; Abdel Moez, A.

2012-02-01

267

Synthesis, structure, and fluxional behavior of octahedral ruthenium(II) complexes with mixed oxygen-phosphine ligands. [sup 31]P DNMR spectroscopic studies, line shape analysis, and determination of rearrangement barriers  

Microsoft Academic Search

The synthesis and spectroscopic properties of ether-phosphine ruthenium(II) complexes of the type Cl[sub 2]Ru([cflx P O])[sub 2] (5a, 7a-10a) and trans-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (5b, 7b-10b) are reported. Temperature-dependent [sup 31]P NMR spectra of the fluxional complexes 1b-11b and cis-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (1c-3c) were measured and by using a modified version of DNMR5, computer-generated spectra were obtained and fitted

Ekkehard Lindner; Andrea Moeckel; Hermann August Mayer; Hartwig Kuehbauch; Riad Fawzi; Manfred Steimann

1993-01-01

268

Spectroscopic Studies of Lasing Transitions in the Diatomic Mercury Halides.  

National Technical Information Service (NTIS)

The B doublet Sigma(+) goes to X doublet Sigma(+) emission spectra of HgCl, HgBr, and HgI have been photographed and analyzed for the single isotopic species, Hg200 Cl35, Hg200Br79, Hg200I121 and Hg200I129. In every case the vibrational analysis corrobora...

J. Tellinghuisen

1982-01-01

269

Alternating current impedance spectroscopic analysis of biofunctionalized vertically-aligned silica nanospring surface for biosensor applications  

NASA Astrophysics Data System (ADS)

In this study, alternating current impedance spectroscopic analysis of the biofunctionalization process of a vertically-aligned (silica) nanosprings (VANS) surface is presented. The VANS surface is functionalized with a biotinylated immunoglobulin G (B-IgG) layer formed by physisorption of B-IgG from the solution phase. Bovine serum albumin passivation of the B-IgG layer reduces additional surface adsorption by blocking the potential sites of weak bond formation via electrostatic and hydrophobic interactions. As avidin acts as a receptor of biotinylated compounds, avidin conjugated glucose oxidase (Av-GOx) binds to the B-IgG layer via biotin. This avidin-biotin bond is a stable bond with high association affinity (Ka = 1015 M-1) that withstands wide variations in chemistry and pH. An IgG layer without biotin shows no binding to the Av-GOx, indicating that bonding is through the avidin-biotin interaction. Finally, fluoroscein iso-thiocyanate (FITC) labeled biotinylated bovine serum albumin (B-BSA) added to the Av-GOx surface is used to fluorescently label Av-GOx for fluorescent measurements that allow for the correlation of surface binding with impedance measurements. Modeling of impedance spectra measured after the addition of each biological solution indicates that the bimolecular layers behave as insulating layers. The impedance spectra for the VANS-based sensor are compared to simple parallel capacitor sensors, sans VANS, and serve as controls. VANS-based sensors exhibit a greater magnitude of change between successive bio-layers relative to the controls below 10 kHz. Changes in the magnitudes of the components of the VANS equivalent circuit indicate that the addition of biological layers changes the effective dielectric response of the VANS via the impediment of ionic motion and biomolecule polarization.

Timalsina, Yukta P.; Branen, Joshua; Aston, D. Eric; Noren, Kenneth; Corti, Giancarlo; Schumacher, Randi; McIlroy, David N.

2011-07-01

270

Calibration method for spectroscopic systems  

DOEpatents

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

Sandison, D.R.

1998-11-17

271

Spectroscopic studies on light proton-rich nuclei  

SciTech Connect

A systematic for the light proton rich nuclei with constant TZ = -3/2 isospin is proposed, where a survey on their structure have shown interesting features. Preliminary results of a re-analysis on the sctructure of 13O nucleus is also presented. This 13O nucleus have been investigated by the 3-neutron pick up (3He,6He) reaction, and new levels have been assigned for this nucleus.

Guimaraes, V.; Lichtenthaler, R. [Instituto de Fisica da USP, 05508-900 Sao Paulo (Brazil); Kubono, S. [Center for Nuclear Study - University of Tokyo, Saitama (Japan); Tanaka, M. H.; Nomura, T.; Katayama, I. [KEK, Tsukuba (Japan); Kato, S. [Yamagata University, Tokyo (Japan)

2007-02-12

272

Infrared and Raman imaging for characterizing complex biological materials: a comparative morpho-spectroscopic study of colon tissue.  

PubMed

Complementary diagnostic methods to conventional histopathology are currently being investigated for developing rapid and objective molecular-level understanding of various disorders, especially cancers. Spectral histopathology using vibrational spectroscopic imaging has been put in the frontline as potentially promising in this regard as it provides a "spectral fingerprint" of the biochemical composition of cells and tissues. In order to ascertain the feasible conditions of vibrational spectroscopic methods for tissue-imaging analysis, vibrational multimodal imaging (infrared transmission, infrared-attenuated total reflection, and Raman imaging) of the same colon tissue has been implemented. The spectral images acquired were subjected to multivariate clustering analysis in order to identify on a molecular level the constituent histological organization of the colon tissue such as the epithelium, connective tissue, etc., by comparing the cluster images with the histological reference images. Based on this study, a comparative analysis of important factors involved in the vibrational multimodal imaging approaches such as image resolution, time constraints, their advantages and limitations, and their applicability to biological tissues has been carried out. Out of the three different vibrational imaging modalities tested, infrared-attenuated total reflection mode of imaging appears to provide a good compromise between the tissue histology and the time constraints in achieving similar image contrast to that of Raman imaging at an approximately 33-fold faster measurement time. The present study demonstrates the advantages, the limitations of the important parameters involved in vibrational multimodal imaging approaches, and their potential application toward imaging of biological tissues. PMID:24405955

Nallala, Jayakrupakar; Piot, Olivier; Diebold, Marie-Danièle; Gobinet, Cyril; Bouché, Olivier; Manfait, Michel; Sockalingum, Ganesh D

2014-01-01

273

Comparison of different metrics for analysis and visualization in spectroscopic optical coherence tomography.  

PubMed

Spectroscopic Optical Coherence Tomography (S-OCT) extracts depth resolved spectra that are inherently available from OCT signals. The back scattered spectra contain useful functional information regarding the sample, since the light is altered by wavelength dependent absorption and scattering caused by chromophores and structures of the sample. Two aspects dominate the performance of S-OCT: (1) the spectral analysis processing method used to obtain the spatially-resolved spectroscopic information and (2) the metrics used to visualize and interpret relevant sample features. In this work, we focus on the second aspect, where we will compare established and novel metrics for S-OCT. These concepts include the adaptation of methods known from multispectral imaging and modern signal processing approaches such as pattern recognition. To compare the performance of the metrics in a quantitative manner, we use phantoms with microsphere scatterers of different sizes that are below the system's resolution and therefore cannot be differentiated using intensity based OCT images. We show that the analysis of the spectral features can clearly separate areas with different scattering properties in multi-layer phantoms. Finally, we demonstrate the performance of our approach for contrast enhancement in bovine articular cartilage. PMID:24409393

Jaedicke, Volker; Agcaer, Semih; Robles, Francisco E; Steinert, Marian; Jones, David; Goebel, Sebastian; Gerhardt, Nils C; Welp, Hubert; Hofmann, Martin R

2013-01-01

274

Renaissance patinas in Úbeda (Spain): mineralogic, petrographic and spectroscopic study  

Microsoft Academic Search

Different analytical techniques were used for microstructural and compositional analysis of the ochre-coloured patinas that\\u000a appear on the calcarenite substrate of monuments in the historical settings of Úbeda and Baeza (Spain). Optical microscopy,\\u000a scanning electron microscopy–energy dispersive x-ray spectrometry (SEM-EDX), x-ray diffraction, Raman spectroscopy and attenuated\\u000a total reflection–Fourier transform infrared spectroscopy (ATR-FTIR) were employed and a critical comparison of their

M. J. Campos-Suñol; A. Domínguez-Vidal; M. J. De la Torre-López

2008-01-01

275

A decade of coronagraphic and spectroscopic studies of CME-driven shocks  

NASA Astrophysics Data System (ADS)

Shocks driven by Coronal Mass Ejections (CMEs) are primary agents of space weather. They can accelerate particles to high energies and can compress the magnetosphere thus setting in motion geomagnetic storms. For many years, these shocks were studied only in-situ when they crossed over spacecraft or remotely through their radio emission spectra. Neither of these two methods provides information on the spatial structure of the shock nor on its relationship to its driver, the CME. In the last decade, we have been able to not only image shocks with coronagraphs but also measure their properties remotely through the use of spectroscopic and image analysis methods. Thanks to instrumentation on STEREO and SOHO we can now image shocks (and waves) from the low corona, through the inner heliosphere, to Earth. Here, we review the progress made in imaging and analyzing CME-driven shocks and show that joint coronagraphic and spectrscopic observations are our best means to understand shock physics close to the Sun.

Vourlidas, Angelos; Bemporad, Alessandro

2012-05-01

276

Spectroscopic studies of the size and composition of single aerosol droplets  

NASA Astrophysics Data System (ADS)

The characterization of aerosol properties and processes, non-intrusively and directly, poses a severe analytical challenge. In order to understand the role of aerosols in often complex environments, it is necessary to probe the particles in situ and without perturbation. Sampling followed by end-of-line analysis can lead to perturbations in particle composition, morphology and size, particularly when analysing liquid aerosol droplets containing volatile components. Optical spectroscopy can provide a strategy for the direct assessment of particle size, composition and phase. We review here the application of linear and non-linear Raman spectroscopies in the characterization of liquid aerosol droplets. Spontaneous Raman scattering can allow the unambiguous identification of chemical components and the determination of droplet composition. Stimulated Raman spectroscopy can allow the determination of droplet size with nanometre accuracy and can allow the characterization of near-surface composition. When combined, the mixing state and homogeneity in droplet composition can be investigated. We highlight some applications of these spectroscopic techniques in studies of the kinetics of particle transformation, the equilibrium composition of aqueous aerosol droplets, and the coagulation and mixing state of organic and aqueous aerosol components. Specifically, we examine the heat and mass transfer accompanying the evaporation of volatile components from liquid droplets, the equilibrium size of aqueous/sodium chloride droplets with varying relative humidity, and the mixing of the immiscible decane and water components during droplet coagulation. We conclude by considering the potential of these techniques for improving our understanding of aerosol properties and processes.

Reid, Jonathan P.; Meresman, Helena; Mitchem, Laura; Symes, Rachel

277

Synthesis and spectroscopic studies of some chromium and molybdenum derivatives of bis-(acetylacetone)ethylenediimine ligand  

NASA Astrophysics Data System (ADS)

Interaction of [Cr(CO)6] with bis-(acetylacetone)ethylenediimine Schiff base, H2acacen, under reduced pressure resulted in the formation of [Cr(CO)3(H2acacen)] derivative. The Schiff base acted as a tridentate and coordinated the metal through the nitrogen of the azomethine groups and one hydroxyl group. Reaction of [Mo(CO)6] with H2acacen under sunlight irradiation in presence of air gave the oxo derivative [Mo2O6(H2acacen)2]. The ligand acted as a bidentate and coordinated the metal through the two imine groups. In presence of 2,2'-bipyridine (bpy), the reaction of [Mo(CO)6] with H2acacen gave [Mo2O6(bpy)(H2acacec)]. The structures of the reported complexes were proposed on the basis of spectroscopic studies. The proposed structures were also verified by theoretical calculations based on accurate DFT approximations. Moreover, the relative reactivity was estimated using chemical descriptors analysis.

Ramadan, Ramadan M.; Abdel-Rahman, Laila H.; Ismael, Mohamed; Youssef, Teraze A.; Ali, Saadia A.

2013-10-01

278

Ab initio and Rotational Spectroscopic Study of Propylene Oxide -- (Water)N=2\\/3 Complexes  

Microsoft Academic Search

Water is the principal constituent of the environment for all living organisms. Nearly all biological molecules required for life are chiral. Therefore the studies of the solvation of chiral molecules in water are of fundamental importance to life science. In this work, we report ab initio and rotational spectroscopic studies of the hydrogen bonded propylene oxide (PO) -- (H2O)N =2\\/3

Zheng Su; Yunjie Xu

2007-01-01

279

Resonance Raman spectroscopic study of fused multiporphyrin linear arrays  

NASA Astrophysics Data System (ADS)

For prospective applications as molecular electric wires, triply linked fused porphyrin arrays have been prepared. As expected from their completely flat molecular structures, ?-electron delocalization can be extended to the whole array manifested by a continuous redshift of the HOMO-LUMO transition band to infrared region up to a few ?m as the number of porphyrin units in the array increases. To gain an insight into the relationship between the molecular structures and electronic properties, we have investigated resonance Raman spectra of fused porphyrin arrays depending on the number of porphyrin pigments in the array. We have carried out the normal mode analysis of fused porphyrin dimer based on the experimental results including Raman frequency shifts of two types of 13C-isotope substituted dimers, Raman enhancement pattern by changing excitation wavelength, and depolarization ratio measurements as well as normal-mode calculations at the B3LYP/6-31G level. In order to find the origins for the resonance Raman mode enhancement mechanism, we have predicted both the excited state geometry changes (A-term) and the vibronic coupling efficiencies (B-term) for the relevant electronic transitions based on the INDO/S-SCI method. A detailed normal mode analysis of the fused dimer allows us to extend successfully our exploration to longer fused porphyrin arrays. Overall, our investigations have provided a firm basis in understanding the molecular vibrations of fused porphyrin arrays in relation to their unique flat molecular structures and rich electronic transitions.

Jeong, Dae Hong; Jang, Sung Moon; Hwang, In-Wook; Kim, Dongho; Matsuzaki, Yoichi; Tanaka, Kazuyoshi; Tsuda, Akihiko; Nakamura, Takeshi; Osuka, Atsuhiro

2003-09-01

280

CD Spectroscope  

NSDL National Science Digital Library

In this activity, learners use an old CD to construct a spectroscope, a device that separates light into its component colors. Learners will hold it up to various light sources to examine how different light has different color strengths. Use this activity to introduce learners to the color spectrum and the tools scientists use to study it.

University, Colorado S.

2009-01-01

281

Spectroscopic study on sorption of hydrogen sulfide by means of red soil.  

PubMed

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. PMID:15911419

Ko, T H; Chu, H

2005-07-01

282

Laser-induced breakdown spectroscopic study of ammonium nitrate plasma  

NASA Astrophysics Data System (ADS)

We present the optical emission studies of the ammonium nitrate plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Q-switched Nd: YAG laser. The target material was placed in front of the laser beam in an open atmospheric air. The spectrum reveals numerous transitions of neutral nitrogen. We have studied the spatial behavior of the plasma temperature ( T e ) and electron number density ( N e ) determined using the Boltzmann plot method and Stark broadened line profiles, respectively. Besides, we have studied the variation of the plasma parameters as a function of the laser irradiance.

Hanif, M.; Salik, M.; Baig, M. A.

2013-12-01

283

Spectroscopic study of the humification process during sewage sludge treatment  

NASA Astrophysics Data System (ADS)

The aim of this work was to study the free radical transition of organic materials during the sewage treatment process. Investigations of sludge from biologic-mechanical sewage treatment plant in Sosnowiec Zagórze were carried out. The course of the humification processes during sewage treatment was studied by electron paramagnetic resonance (EPR) technique. The concentration of free radicals at each process stage and the value g were determined. Sludge samples and extracted fractions of humic acids were examined. Humic acids were extracted from sludge by means of conventional methods elaborated by Stevenson. For study of humic acids structures, besides EPR, the UV-Vis and IR spectroscopy were used.

Paj?czkowska, J.; Su?kowska, A.; Su?kowski, W. W.; J?drzejczyk, M.

2003-06-01

284

Mihaliccik Tremolite: An XRD, FTIR and Raman Spectroscopic Study  

NASA Astrophysics Data System (ADS)

Tremolite sample used in this study was obtained from Tatarcik deposits of Mihaliccik region of Turkey and characterized by X-ray diffraction, energy dispersive spectroscopy, Raman, and Fourier transform infrared spectroscopy methods.

Izci, E.

2014-06-01

285

Separation and Spectroscopic Study of Exotic Nuclei at GANIL.  

National Technical Information Service (NTIS)

A new isotopic separation method is presented. It permits studies of radioactive atomic nuclei produced in high energy heavy ions collisions. Two experiments were performed at the GANIL facilities (Grand Accelerateur National d'Ions Lourds, Caen). They ar...

D. Jean

1987-01-01

286

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...

287

Spectroscopic study of phase transitions in natural calcite mineral  

NASA Astrophysics Data System (ADS)

The process and the formation of new minerals upon heating the carbonate rocks containing clay minerals, together with calcite are determined with thermal analysis, X-ray diffraction, infrared and Raman spectroscopy. The calcite-calcium oxide phase transition sequence was followed up to 947 °C in naturally occurring limestone samples. The spectral variations of the internal modes of the carbonate trigonal ( ?1, ?2, ?3 and ?4) were used to probe the structural phase transitions. The calcium oxide phase (which on reaction with atmospheric water forms portlandite) with an onset temperature of around 950 °C was also characterized by the appearance of the infrared mode around 450 cm -1. The minerals, which were formed upon heating the calcite, were calcium oxide and wollastonite.

Gunasekaran, S.; Anbalagan, G.

2008-04-01

288

Spectroscopic Studies of SRTIO3 Using Impurity Ion Probes.  

National Technical Information Service (NTIS)

Studies were made of the properties of SrTiO3 using the impurity ions Cr(3+) and Mn(4+) as probes. Sharp line fluorescence and absorption in the region of 7930A were observed in Cr(3+) doped and undoped SrTiO3. Fluorescence from Mn(4+) doped SrTiO3 was al...

S. E. Stokowski

1968-01-01

289

Phase transition in ethylenetetrafluoroethylene (ETFE) alternating copolymer. A spectroscopic study  

Microsoft Academic Search

The study of temperature dependent infrared (i.r.) and Raman spectra of alternating ethylenetetrafluoroethylene (ETFE) copolymer suggests that the transition from orthorhombic to hexagonal phases may be driven by the generation and propagation of conformational solitons (gentle mobile chain twist).

G. Zerbi

1997-01-01

290

Spectroscopic and ion exchange studies on modified cotton linters  

Microsoft Academic Search

Cation exchange resin was prepared by phosphorylation of cotton linters. The effect of different treatments (alkali or acid) of cotton linters on phosphorylation process was studied. This treatment increases the efficiency of the produced resin toward metal ions uptake (Cu, Fe, Mn, Ni, Pb, Zn). The effect of pH value of metal ion solution on the efficiency of ion exchanger

A M A Nada; S S Hamed; S I Soliman; S Abd El Mongy

291

Natural fluorescence of white blood cells: spectroscopic and imaging study  

Microsoft Academic Search

Autofluorescence has been proved to be an intrinsic parameter of biological substrates that may aid in both the characterization of the physiological state and the discrimination of pathological from normal conditions of cells, tissues and organs. In this work, the fluorescence properties of human white blood cells have been studied in suspension and on single cells at microscopy. The results

Monica Monici; Riccardo Pratesi; Pietro A. Bernabei; Roberto Caporale; Pierluigi Rossi Ferrini; Anna Cleta Croce; Piera Balzarini; Giovanni Bottiroli

1995-01-01

292

Raman spectroscopic studies of carbon in extra-terrestrial materials  

Microsoft Academic Search

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

John Macklin; Donald Brownlee; Sherwood Chang; Ted Bunch

1990-01-01

293

Sum frequency generation vibrational spectroscopic studies on buried heterogeneous biointerfaces.  

PubMed

A sum frequency generation (SFG) vibrational micro-spectroscopy system was developed to examine buried heterogeneous biointerfaces. A compact optical microscope was constructed with total-internal reflection (TIR) SFG geometry to monitor the tightly focused SFG laser spots on interfaces, providing the capability of selectively probing different regions on heterogeneous biointerfaces. The TIR configuration ensures and enhances the SFG signal generated only from the sample/substrate interfacial area. As an example for possible applications in biointerfaces studies, the system was used to probe and compare buried interfacial structures of different biological samples attached to underwater surfaces. We studied the interface of a single mouse oocyte on a silica prism to demonstrate the feasibility of tracing and studying a single live cell and substrate interface using SFG. We also examined the interface between a marine mussel adhesive plaque and a CaF2 substrate, showing the removal of interface-bonded water molecules. This work also paves the way for future integration of other microscopic techniques such as TIR-fluorescence microscopy or nonlinear optical imaging with SFG spectroscopy for multimodal surface or interface studies. PMID:24784085

Zhang, Chi; Jasensky, Joshua; Leng, Chuan; Del Grosso, Chelsey; Smith, Gary D; Wilker, Jonathan J; Chen, Zhan

2014-05-01

294

Effect of surfactants on casein structure: A spectroscopic study  

Microsoft Academic Search

Fluorescence and circular dichroism spectroscopy were used to study the effect of two surfactants having oppositely charged head groups – cationic cetyltrimethyl ammonium bromide (CTAB) and anionic sodium dodecyl sulphate (SDS) – on the structure of the intrinsically unstructured proteins ?s-, ?- and ?-caseins. Although globular proteins are generally known to denature on interacting with surfactants, the caseins were found

Asima Chakraborty; Soumen Basak

2008-01-01

295

Spectroscopic Study of Soil Particle Surface Redox Reactions  

Microsoft Academic Search

influence its solubility, mobility and toxicity. Quantitative examination of redox reactions are challenging in soils for a number of reasons ,including: a lack of reliable analytical methods to study reactions; the heterogeneity of the mineral components and redox systems occurring in nature; the irreversibility or slow approach to equilibrium of many redox reactions; and the probability that many redox reactions

J. A. Risser; G. W. Bailey

1997-01-01

296

Spectroscopic studies of the active site of galactose oxidase  

SciTech Connect

X-ray absorption and EPR spectroscopy have been used to probe the copper site structure in galactose oxidase at pH 4.5 and 7.0. the results suggest that there are no major differences in the structure of the tetragonal Cu(II) site at these pH values. Analysis of the extended X-ray absorption fine structure (EXAFS) indicates that four N,O scatterers are present at approximately 2 {Angstrom}; these are presumably the equatorial ligands. In addition, the EXAFS data establish that oxidative activation to produce the active-site tyrosine radical does not cause major changes in the copper coordination environment. Therefore results obtained on the one-electron reduced enzyme, containing Cu(II) but not the tyrosine radical, probably also apply to the catalytically active Cu(II)/tyrosine radical state. Solvent water exchange, inhibitor binding, and substrate binding have been probed via nuclear magnetic relaxation dispersion (NMRD) measurements. The NMRD profile of galactose oxidase is quantitatively consistent with the rapid exchange of a single, equatorial water ligand with a Cu(II)-O separation of about 2.4 {Angstrom}. Azide and cyanide displace this coordinated water. The binding of azide and the substrate dihydroxyacetone produce very similar effects on the NMRD profile of galactose oxidase, indicating that substrates also bind to the active site Cu(II) in an equatorial position.

Knowles, P.F. [Univ. of Leeds (United Kingdom); Brown, R.D. III; Koenig, S.H. [IBM, Yorktown Heights, NY (United States)] [and others

1995-07-19

297

EXAFS spectroscopic studies of uranium(VI) oxide precipitates  

SciTech Connect

We have investigated the structures of U(VI) oxides precipitated from room temperature aqueous solutions at low ionic strength as a function of pH. Using the uranium L{sub III} - edge extended x-ray absorption fine structure (EXAFS) as a probe of the local structure around the uranium, a trend is observed whereby the axial oxygen bond lengths from the uranyl groups increase from 1.80 {Angstrom} at pH=7 to 1.86 {Angstrom} at pH=11. A concomitant decrease in the equatorial oxygen and nearest-neighbor uranium bond lengths also occurs with increasing pH. Expansion of the linear O=U=O group is seen directly at the L{sub III} absorption edge where multiple scattering resonances systematically shift in energy. EXAFS curve-fitting analysis on these precipitates and a sample of synthetic schoepite indicate that the structure of the species formed at pH=7 is similar to the structure of schoepite. At pH=11, the precipitate structure is similar to that of a uranate.

Allen, P.G. [Lawrence Berkeley National Lab., CA (United States)]|[Lawrence Livermore National Lab., CA (United States); Shuh, D.K.; Bucher, J.J. [Lawrence Berkeley National Lab., CA (United States)] [and others

1996-04-01

298

Femtosecond spectroscopic study of carminic acid DNA interactions  

NASA Astrophysics Data System (ADS)

Photo-excited carminic acid and carminic acid-DNA complexes in a buffer solution at pH 7 have been examined using a variety of spectroscopy techniques, that are in particular, the femtosecond resolved fluorescence upconversion and transient absorption spectroscopy. The observation of dual fluorescence emission, one peaks at 470 nm and the other at 570 nm, indicates to an excited-state (S 1) intramolecular proton transfer (ESIPT). A detailed analysis of the transient absorption measurements of an aqueous carminic-acid solution at pH 7 yielded four lifetimes for the excited-state (S 1): 8, 15, 33 and 46 ps. On the other hand, only two lifetimes, 34 and 47 ps, were observed by fluorescence upconversion spectroscopy because of the detection limitation to the long wavelength edge of the carminic-acid spectrum. The four S 1 lifetimes were ascribed to the coexistence of respectively two tautomer (normal and tautomer) forms of carminic acid, in the non-dissociated state (CAH) and in the deprotonated state (CA -). The fluorescence upconversion measurements of carminic acid-DNA complexes exhibited a prolongation of the fluorescence lifetimes. This effect was accepted as evidence for the formation of intercalation complexes between the carminic acid and the DNA. The intercalative binding of the carminic acid to DNA was confirmed by the fluorescence titration experiments resulting to a binding constant of 2 × 10 5 M -1 that is typical for anthracycline-DNA complexes.

Comanici, Radu; Gabel, Bianca; Gustavsson, Thomas; Markovitsi, Dimitra; Cornaggia, Christian; Pommeret, Stanislas; Rusu, Catalin; Kryschi, Carola

2006-06-01

299

Spectroscopic studies of the interfacial interactions between polymers and nanostructures  

NASA Astrophysics Data System (ADS)

Optical and vibrational spectroscopies are used to study the interactions of various polymers with several nanoscopic materials. First, two new conjugated polymers manufactured by the Ferraris Group in the Department of Chemistry at The University of Texas at Dallas, poly [1,4-bis-2-ethylhexylmercapto]- p-phenylenevinylene (BEHM-PPV)and poly [1,4-bis-(2-ethylhexyl-sulfinyl)]- p-phenylenevinylene (BEHSO-PPV) are studied along with poly (2,5-bis (2'-ethylhexyloxy)-1,4-p-phenylenevinylene) (BEH-PPV). It is found that the two sulphur containing polymers BEHM-PPV and BEHSO-PPV have a greater tendency to aggregate than does BEH-PPV, and also have bluer photoluminescence. These three polymers are then studied in composite with single walled carbon nanotubes where charge transfer occurs across the interface from the polymer to the nanotubes. These three polymers are studied in mixture with aggregated quantum dots, where it is seen that the quantum dot aggregation prevents significant interactions to occur. The energy transfer interaction between conjugated polymers and transparent, conducting multiwalled carbon nanotubes films is investigated. It is found that a coating of PEDOT-PSS between the nanotubes and conjugated polymer suppresses the quenching of photoluminescence. This effect is important for enhancement of electroluminescence of organic LED devices, in which MWCNT hole injectors are used instead of the usual ITO. The University of Texas developed peptide nano-1 has been shown to engage in charge transfer interactions with SWNTs and, perhaps more importantly, can enable self assembly of complex nanotube structures. Finally, poly [2-methoxy-5-(2'-ethylhexyloxy)- p-phenylenevinylene] (MEH-PPV) and poly[3-hexyl thiophene] (P3HT) are studied in composite with titanium dioxide and an increase in the photoluminescence is seen, induced by interfacial interactions between the polymer and TiO 2. An explanation based on polaron mediated triplet to singlet exciton conversion is presented as an explanation for this effect.

Sampson, William M.

300

Hemodynamic analysis of patients in intensive care unit based on diffuse optical spectroscopic imaging system  

NASA Astrophysics Data System (ADS)

Diffuse optical spectroscopic imaging (DOSI) is a technique to assess the spatial variation in absorption and scattering properties of the biological tissues and provides the monitoring of changes in concentrations of oxy-hemoglobin and deoxy-hemoglobin. In our preliminary study, the temporal tracings of hemodynamic oxygenation are measured with DOSI and venous occlusion test (VOT) from normal subjects, patients with heart failure and patients with sepsis in intensive care unit (ICU). In experiments, the obvious differences of hemodynamic signals can be observed among the three groups. The physiological relevance of VOT hemodynamics with respect to diseases is also discussed in this paper.

Hsieh, Yao-Sheng; Wang, Chun-Yang; Ling, Yo-Wei; Chuang, Ming-Lung; Chuang, Ching-Cheng; Tsai, Jui-Che; Lu, Chih-Wei; Sun, Chia-Wei

2010-02-01

301

Studies of tropical fruit ripening using three different spectroscopic techniques.  

PubMed

ABSTRACT. We present a noninvasive method to study fruit ripening. The method is based on the combination of reflectance and fluorescence spectroscopies, as well as gas in scattering media absorption spectroscopy (GASMAS). Chlorophyll and oxygen are two of the most important constituents in the fruit ripening process. Reflectance and fluorescence spectroscopies were used to quantify the changes of chlorophyll and other chromophores. GASMAS, based on tunable diode laser absorption spectroscopy, was used to measure free molecular oxygen in the fruit tissue at 760 nm, based on the fact that the free gases have much narrower spectral imprints than those of solid materials. The fruit maturation and ripening processes can be followed by studying the changes of chlorophyll and oxygen contents with these three techniques. PMID:24887745

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

2014-06-01

302

A Mössbauer spectroscopic study of cobalt-iron molybdates  

NASA Astrophysics Data System (ADS)

Fe x Co1- x MoO4 compounds prepared by coprecipitation were studied by XRD, electrical conductivity and mainly by absorption and emission Mössbauer spectroscopy. FeMoO4 and CoMoO4 samples were shown to contain Fe3+ and Co3+, respectively, in solid solution. Three kinds of Fe x Co1- x MoO4 solids can be described. For x?0.16: one has a ?-Co(Fe2+, Fe3+)MoO4 solid solution. For 0.17? x?0.25: one has the same solid solution with its surface rich in Fe3+. For x?0.26: one has the same solid solution with only bulk Fe3+, and ferric molybdate. Studies of reduction by hydrogen and of catalytic reaction of mechanical mixtures of CoMoO4 and ferric molybdate support these statements.

Benaïchouba, B.; Bussière, P.; Védrine, J. C.

1996-12-01

303

An infrared and Raman spectroscopic study of natural zinc phosphates  

NASA Astrophysics Data System (ADS)

Zinc phosphates are important in the study of the phosphatisation of metals. Raman spectroscopy in combination with infrared spectroscopy has been used to characterise the zinc phosphate minerals. The minerals may be characterised by the patterns of the hydroxyl stretching vibrations in both the Raman and infrared spectra. Spencerite is characterised by a sharp Raman band at 3516 cm -1 and tarbuttite by a single band at 3446 cm -1. The patterns of the Raman spectra of the hydroxyl stretching region of hopeite and parahopeite are different in line with their differing crystal structures. The Raman spectrum of the PO 4 stretching region shows better band separated peaks than the infrared spectra which consist of a complex set of overlapping bands. The position of the PO 4 symmetric stretching mode can be used to identify the zinc phosphate mineral. It is apparent that Raman spectroscopy lends itself to the fundamental study of the evolution of zinc phosphate films.

Frost, Ray L.

2004-06-01

304

Spectroscopic Studies of Poly(?-Caprolactone)/Sodium Montmorillonite Nanocomposites  

NASA Astrophysics Data System (ADS)

Polymer-layered silicate nanocomposites belong to a new class of hybrid materials consisting of organic-synthetic polymer matrix and inorganic filler-layered structure clay minerals. The paper presents the results of FTIR, NMR, and SAXS studies of poly(?-caprolactone)/sodium montmorillonite nanocomposites. We observed a correlation between the concentration of poly(?-caprolactone) in nanocomposite samples and structural changes both of the clay mineral and the intercalated polymer. Stiffening of the clay structure appears as a result of poly(?-caprolactone) intercalation into a clay structure. 27Al NMR studies indicated in nanocomposites two non-equivalent sites of aluminium ions, i.e. in octahedral and tetrahedral coordination, whereas in the montmorillonite clay structure the aluminium ions are located in the interlayer space too. We found also that the temperatures of structural changes and softening process of poly(?-caprolactone) chains in the nanocomposites depend on the concentration of poly(?-caprolactone).

Krzaczkowska, J.; Fojud, Z.; Kozak, M.; Jurga, S.

2006-07-01

305

Spectroscopic studies of GTA welding plasmas. Temperature calculation and dilution measurement  

NASA Astrophysics Data System (ADS)

A spectroscopic study of the GTAW plasma-plume created during the welding of stainless steel and other materials (iron, nickel and chromium) has been carried out. The spectra of these plasmas have been studied for several welding parameters. Temperature calculations are based on the observation of relative intensities and shapes of the emission peaks. We assume that the plasma is in local thermal equilibrium. The temperature is calculated with the Boltzmann plot method from twelve iron emission lines (in the range 368 385 nm): it varies between 9650 and 12 100 K. Dilution experiments have been carried out. We checked the mixing of metals: during welding of two different metallic plates and during welding with an Inconel wire. Dilution is monitored following the intensity of some characteristic emission lines (chromium and nickel). Comparison of spectroscopic results and metallographic ones is made.

Lacroix, D.; Boudot, C.; Jeandel, G.

1999-10-01

306

Studies of Surfaces and Films Using Spectroscopic Ellipsometry  

Microsoft Academic Search

Two, high-precision, automatic rotating analyzer ellipsometer have been built and tested. One is a variable angle system suitable for measuring samples at room temperature in an inert gas environment. The second is a fixed angle (70.45^circ) ultrahigh vacuum (UHV) instrument equipped with reflection high energy electron diffraction (RHEED) used to study in situ film growth. Both ellipsometer systems operate over

Songlin Ren

1992-01-01

307

Raman spectroscopic studies on the sulfation of cerium oxide  

Microsoft Academic Search

In the present study, we have examined sulfation of cerium oxide via impregnation of (NH4)2SO4, followed by heating in the temperature range of 220–720°C, using Raman Spectroscopy. Based on the SO and SO stretching frequencies in the range of 900–1400 cm?1, a wide range of surface oxysulfur species and bulk cerium-oxy-sulfur species are identified. At 220°C, a mixture of (NH4)2SO4

Jen Twu; Chung Jen Chuang; Kuang I Chang; Ching Hsiang Yang; Kuei Hsien Chen

1997-01-01

308

Raman spectroscopic study of left-handed Z-RNA  

SciTech Connect

The solvent conditions that induce the formation of a left-handed Z form of poly(r(G-C)) have been extended to include 6.5 M NaBr at 35/sup 0/C and 3.8 M MgCl/sub 2/ at room temperature. The analysis of the A ..-->.. Z transition in RNA by circular dichroism (CD), /sup 1/H and /sup 31/P NMR, and Raman spectroscopy shows that two distinct forms of left-handed RNA exist. The Z/sub R/-RNA structure forms in high concentrations of NaBr and NaClO/sub 4/ and exhibits a unique CD signature. Z/sub D/-RNA is found in concentrated MgCl/sub 2/ and has a CD signature similar to the Z form of poly(d(G-C)). Significant differences in the glycosyl angle and sugar pucker between Z-DNA and Z-RNA are suggested by the 16-cm/sup -1/ difference in the position of this band. The Raman evidence for structural difference between Z/sub D/- and Z/sub R/-RNA comes from two groups of bands: First, Raman intensities between 1180 and 1600 cm/sup -1/ of Z/sub D/-RNA differ from those for Z/sub R/-RNA, corroborating the CD evidence for differences in base-stacking geometry. Second, the phosphodiester stretching bands near 815 cm/sup -1/ provide evidence of differences in backbone geometry between Z/sub D-/ and Z/sub R/-RNA.

Trulson, M.O.; Cruz, P.; Puglisi, J.D.; Tinoco, I. Jr.; Mathies, R.A.

1987-12-29

309

X-ray spectroscopic studies of microbial transformations of uranium  

SciTech Connect

Several uranium compounds U-metal ({alpha}-phase), UO{sub 2}, U{sub 3}O{sub 8}, {gamma}-UO{sub 3}, uranyl acetate, uranyl nitrate, uranyl sulfate, aqueous and solid forms of 1:1 U:citric acid and 1:1:2 U:Fe:citric acid mixed-metal complexes, and a precipitate obtained by photodegradation of the U-citrate complex were characterized by X-ray spectroscopy using XPS, XANES, and EXAFS. XPS and XANES were used to determine U oxidation states. Spectral shifts were obtained at the U 4f{sub 7/2} and U 4f{sub 5/2} binding energies using XPS, and at the uranium M{sub V} absorption edge using XANES. The magnitude of the energy shift with oxidation state, and the ability to detect mixed-valent forms make these ideal techniques for determining uranium speciation in wastes subjected to bacterial action. The structure of 1:1 U:citric acid complex in both the aqueous and solid state was determined by EXAFS analysis of hexavalent uranium at the L{sub M} absorption edge and suggests the presence of a binuclear complex with a (UO{sub 2}){sub 2}({mu},{eta}{sup 2} {minus}citrato){sub 2} core with a U-U distance of 5.2 {angstrom}. The influence of Fe on the structure of U-citrate complex was determined by EXAFS and the presence of a binuclear mixed-metal citrate complex with a U-Fe distance of 4.8 {angstrom} was confirmed. The precipitate resulting from photodegradation of U-citrate complex was identified as an amorphous form of uranium trioxide by XPS and EXAS.

Dodge, C.J.; Francis, A.J. [Brookhaven National Lab., Upton, NY (United States); Clayton, C.R. [SUNY at Stony Brook, Stony Brook, NY (United States). Dept. of Materials Science and Engineering

1995-10-01

310

Virgin and recycled engine oil differentiation: a spectroscopic study.  

PubMed

As a result of the changes that occur during their use, used engine oils tend to differ in chemical and physical composition from a virgin oil. In general recycled oils have: much higher water and sediment levels than virgin oil; relatively higher concentrations of organic compounds (oxidation products); and relatively higher levels of metals such as Fe, Cd, Cr, Pb, etc. Therefore, the aim of this work was to investigate, assess and to observe, by means of the physical and the chemical properties of the oils, atomic absorption (AA), inductive couple plasma (ICP) and Fourier transform infrared (FTIR) analyses the extent of the differences occurring between the virgin and recycled oil. In important part of this work was also the development of analytical techniques based on the use of FTIR spectroscopy; in relation to the rapid analysis of lubricants; in particular for the differentiation of virgin and recycled oil. The results obtained were expected to be useful for differentiation purposes, providing information on whether the metal concentrations and oxidation products could be an appropriate feature for differentiating a particular oil sample from the others. This work is categorized into a two-step procedure. Firstly, an evaluation of a typical FTIR spectrum of an engine oil sample (mono- and multigrade) is presented. The broad feature centered at 1716 cm(-1) is due to the presence of carbonyl containing degradation products of oil. A band observed at 1732, 1169, 1154 and 1270 cm(-1) assigned to the polymethacrylate stretching vibrations, allows the determination of viscosity modifier and pour point depressant additives. The observed differences in the specific spectral bands (1732, 1169, 1154 and 1270 and 1716 cm(-1)) are investigated and discussed. Secondly, an analytical technique for the measurement of the levels of the wear metals is also applied. PMID:18083292

Al-Ghouti, Mohammad A; Al-Atoum, Lina

2009-01-01

311

FT-IR spectroscopic studies of polycyclic aromatic hydrocarbons  

NASA Technical Reports Server (NTRS)

Proper assessment of the hypothesis which correlates polycyclic aromatic hydrocarbons (PAHs) with the unidentified infrared emission bands requires additional experimental laboratory data. In order to address this need, thermal infrared emission studies were performed on a subset of PAHs suggested to be of astrophysical importance. It was proposed that infrared emission from interstellar PAHs occurs following absorption of an ultraviolet photon. Since energy transfer to the ground electronic state can be rapid for a species in which intersystem crossing is negligible, the emission spectrum may be viewed as resulting from an equilibrium vibrational temperature (Leger and d'Hendecourt, 1987). This has been the basis for using infrared absorption spectra to calculate the corresponding emission spectra at various temperatures. These calculations were made using room temperature infrared absorption coefficients instead of those at the temperature of interest because of the latter's unavailability. The present studies are designed to address the differences between the calculated and experimental thermal emission spectra and to provide information which will be useful in future ultraviolet induced infrared fluorescence studies. The emission spectra have been obtained for temperatures up to 825K using an emission cell designed to mount against an external port of an FT-IR spectrometer. These spectra provide information concerning relative band intensities and peak positions which is unavailable from previous calculations.

Salisbury, D. W.; Allen, J. E., Jr.; Donn, B.; Moore, W. J.; Khanna, R. K.

1990-01-01

312

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

SciTech Connect

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 the influence of ILs on charge transport processes. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) [1] are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. IL solvation and rotational dynamics are measured by TCSPC in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy.

WISHART,J.F.

2007-11-30

313

Microparticle electrodes and single particle microbatteries: electrochemical and in situ microRaman spectroscopic studies.  

PubMed

Studies of the intrinsic electrochemical, structural, and electronic propertiesof microparticles of energy storage materials can provide much needed insight into the factors that control various aspects of the performance of technical electrodes for battery applications. This Account summarizes efforts made in our laboratories toward the development and implementation of methods for the in situ electrical, optical, and spectroscopic characterization of microparticles of a variety of such materials, including Ni hydroxide, Zn, carbon, and lithiated Mn and Co oxides. In the case of Ni hydroxide, the much darker appearance of NiOOH compared to the virtually translucent character of virgin Ni(OH)2 allowed for the spatial and temporal evolution of charge flow within spherical microparticles of Ni(OH)2 to be monitored in real time during the first scan toward positive potentials using computer-controlled video imaging. In situ Raman scattering measurements involving single microparticles of Zn harvested from a commercial Zn|MnO2 battery revealed that passive films formed in strongly alkaline solutions by stepping the potential from 1.55 V to either 0.7 or 0.8 V vs SCE displayed a largely enhanced feature at ca. 565 cm(-1) ascribed to a longitudinal optical phonon mode of ZnO, an effect associated with the presence of interstitial Zn and oxygen deficiencies in the lattice. In addition, significant amounts of crystalline ZnO could be detected only for passive films formed at the same two potentials after the electrodes had been roughened by a single passivation-reduction step. Quantitative correlations were found in the case of LiMn2O4 and KS-44 graphite between the Raman spectral properties and the state of charge. In the case of KS-44, a chemometrics analysis of the spectroscopic data in the potential region in which the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur made it possible to determine independently the fraction of each of the two phases present as a function of potential without relying on the coulometric information. Also featured in this Account are methods we developed for the assembly and electrochemical characterization of Zn|MnO2 and nickel|metal-hydride Ni|MH alkaline batteries incorporating single microparticles of the active materials. As evidenced from the data collected, the voltage-time profiles for constant current operation for both types of devices were found to be similar to those of commercially available batteries involving the same chemistries. The ability to monitor the state of charge of individual particles based strictly on spectroscopic data is expected to open exciting new prospects for visualizing the flow of charge within electrodes in Li-ion batteries, an area that is being vigorously pursued in our laboratories. PMID:23530836

Jebaraj, Adriel Jebin Jacob; Scherson, Daniel A

2013-05-21

314

Spectroscopic, thermal and structural studies on manganous malate crystals  

NASA Astrophysics Data System (ADS)

Prismatic crystals of manganous malate have been prepared by controlled ionic diffusion in hydrosilica gel. The structure was elucidated using single crystal X-ray diffraction. The crystals are orthorhombic with space group Pbca. Vibrations of the functional groups were identified by the FTIR spectrum. Thermogravimetric and differential thermal analyses (TG-DTA) were carried out to explore the thermal decomposition pattern of the material. Structural information derived from FTIR and TG-DTA studies is in conformity with the single crystal XRD data.

Thomas, J.; Lincy, A.; Mahalakshmi, V.; Saban, K. V.

2013-01-01

315

Electrochemical and spectroscopic studies of fuel cell reactions  

NASA Astrophysics Data System (ADS)

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 were carried out to address the possible mechanisms for the observed enhancement. The volcano-type dependence of the ORR activity on the d-band center of the noble metal overlayer was established. These results indicate a way for designing new catalysts with greatly improved properties.

Shao, Minhua

316

FTIR spectroscopic and quantum chemical studies on hydantoin  

NASA Astrophysics Data System (ADS)

In this study the geometry optimization of monomeric and dimeric forms (D1, D2, and D3) of hydantoin molecule were done using DFT method employing 6-31++G( d, p) basis set. Harmonic and anharmonic wavenumbers and infrared intensities were computed at the same theory level. Experimental IR spectrum was recorded in the region 400-4000 cm-1. It has also been characterized by 1H and 13C NMR spectrum. The hydrogen bond (HB) interaction of hydantoin was analyzed via dimers of hydantoin. Detailed vibrational wavenumber shifts and all vibrational mode analyses were reported. Total energy distributions (TED, %) calculations were done to characterize the fundamentals.

Ildiz, Gulce Ogruc; Boz, Ismail; Unsalan, Ozan

2012-05-01

317

Mechanism of the electrochemical oligomerization of thionaphteneindole: a spectroscopic study  

NASA Astrophysics Data System (ADS)

The UV, visible and NIR spectra recorded during electrolysis of TNI in CH 2Cl 2 have been studied as a function of electrolysis time and of the quantity of charge exchanged. Among the oligomeric species that might be responsible for the behaviour observed, particular attention has been devoted to dimers of TNI characterized by different charges, presence of unpaired electrons, and deprotonation of the amino hydrogens. A sample of these species has been described theoretically by means of the PM3 semiempirical hamiltonian and their spectra have been computed giving results in reasonable agreement with the observed transitions.

Poggi, Gabriella; Casalbore Miceli, Giuseppe; Beggiato, Giancarlo; Emmi, Salvatore S.

1997-10-01

318

Mössbauer spectroscopic study of iron-chelate trammels  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

319

Spectroscopic studies with the PRISMA-CLARA set-up  

NASA Astrophysics Data System (ADS)

The large solid angle magnetic spectrometer for heavy ions PRISMA, installed at Laboratori Nazionali di Legnaro (LNL), was operated up to the end of March 2008 in conjunction with the highly efficient CLARA set-up. It allowed to carry out nuclear structure and reaction mechanism studies in several mass regions of the nuclide chart. Results obtained in the vicinity of the island of inversion and for the heavy iron and chromium isotopes are presented in this contribution. The status of the new focal plane detectors specifically designed for light ions and slow moving heavy ions is also reported.

Fioretto, E.; Bazzacco, D.; Beghini, S.; Corradi, L.; de Angelis, G.; Farnea, E.; Gadea, A.; Lenzi, S. M.; Lunardi, S.; Mason, P.; Mengoni, D.; Montagnoli, G.; Napoli, D. R.; Sahin, E.; Scarlassara, F.; Silvestri, R.; Stefanini, A. M.; Ur, C. A.; Valiente-Dobón, J. J.; Pollarolo, G.; Szilner, S.; Marginean, N.; PRISMA, the; CLARA Collaborations

2010-01-01

320

A Spectroscopic and Mineralogical Study of Multiple Asteroid Systems  

NASA Astrophysics Data System (ADS)

There are currently ~200 identified multiple asteroid systems (MASs). These systems display a large diversity in heliocentric distance, size/mass ratio, system angular momentum, mutual orbital parameters, and taxonomic class. These characteristics are simplified under the nomenclature of Descamps and Marchis (2008), which divides MASs into four types: Type-1 - large asteroids with small satellites; Type-2 - similar size double asteroids; Type-3 - small asynchronous systems; and Type-4 - contact-binary asteroids. The large MAS diversity suggests multiple formation mechanisms are required to understand their origins. There are currently three broad formation scenarios: 1) ejecta from impacts; 2) catastrophic disruption followed by rotational fission; and 3) tidal disruption. The taxonomic class and mineralogy of the MASs coupled with the average density and system angular momentum provide a potential means to discriminate between proposed formation mechanisms. We present visible and near-infrared (NIR) spectra spanning 0.45 - 2.45 ?m for 23 Main Belt MASs. The data were primarily obtained using the Southern Astrophysical Research Telescope (SOAR) Goodman High Throughput Spectrograph (August 2011 - July 2012) for the visible data and the InfraRed Telescope Facility (IRTF) SpeX Spectrograph (August 2008 - May 2013) for the IR data. Our data were supplemented using previously published data when necessary. The asteroids' Bus-DeMeo taxonomic classes are determined using the MIT SMASS online classification routines. Our sample includes 3 C-types, 1 X-type, 1 K-type, 1 L-type, 4 V-types, 10 S-types, 2 Sq- or Q-types, and 1 ambiguous classification. We calculate the 1- and 2-?m band centers, depths, and areas to determine the pyroxene mineralogy (molar Fs and Wo) of the surfaces using empirically derived equations. The NIR band analysis allows us to determine the S-type subclasses, S(I) - S(VII), which roughly tracks olivine-pyroxene chemistry. A comparison of the orbital parameters, physical parameters (size, density, and angular momentum), collisional family membership, and taxonomy is presented in an effort to find correlations, which may give insights to how these MASs formation mechanisms.

Lindsay, Sean S.; Emery, J. P.; Marchis, F.; Enriquez, J.; Assafin, M.

2013-10-01

321

An 57Fe Mössbauer Spectroscopic and X-ray Diffraction Study of New Zealand Glauconites  

Microsoft Academic Search

A comprehensive M6ssbauer spectroscopic and X-ray diffraction study of six purified glauconites is presented. The M6ssbauer spectra were computer-fitted with three Fe 3+ and three Fe 2+ doublets, both Fe species occupying the trans-OH and two cis-OH octahedral sites. In addition, a seventh smaller doublet is assigned to Fe 3+ in tetrahedral coordination. It has been shown that an increasing

C. M. Cardile; I. W. M. BROWN

1988-01-01

322

Spectroscopic study of vanadium(V) precipitation in the vanadium redox cell electrolyte  

Microsoft Academic Search

In this study, characterisation of vanadium electrolyte and vanadium(V) red precipitate formed in the positive half-cell electrolyte of a vanadium redox cell is present using different spectroscopic techniques. 51V solution NMR showed that the main peak at about ?545 ppm in the spectra of the redox electrolyte could be attributed to the monomer species of VO2+ ions and the intensity

Xiaoqiao Lu

2001-01-01

323

The photophysics of some UV-MALDI matrices studied by using spectroscopic, photoacoustic and luminescence techniques  

NASA Astrophysics Data System (ADS)

The photophysical behaviour of classical UV-MALDI matrices 2,5-dihydroxybenzoic acid (gentisic acid; GA), 2,4,6-trihydroxyacetophenone (THAP), trans-3,5-dimethoxy-4-hydroxycinnamic acid (SA), trans-4-hydroxy-?-ciano-4-hydroxycinnamic acid (CHC), 9H-pirido[3,4-b]indole (nor-harmane; norHo) and 1-methyl-9H-pirido[3,4-b]indole (harmane; Ho) in acetonitrile was studied by using spectroscopic, luminescence and photoacoustic techniques.

Mesaros, Mariana; Tarzi, Olga I.; Erra-Balsells, Rosa; Bilmes, Gabriel M.

2006-08-01

324

Mid-infrared spectroscopic studies of alkali-activated fly ash structure  

Microsoft Academic Search

Infrared spectroscopic techniques were used in the present study to acquire a deeper understanding of mid-range order in the alkaline aluminosilicate (zeolite precursor) formed in the alkali activation of fly ash. Experiments were conducted with three type F fly ashes containing different proportions of vitreous and crystalline (primarily mullite and quartz) phases, activated with an 8M solution of NaOH. All

A. Fernández-Jiménez; A. Palomo

2005-01-01

325

Nuclear shapes from spectroscopic studies of fission fragments  

SciTech Connect

Partial level schemes for several neutron-rich Ba and Ce nuclei have been determined from the study of gamma-gamma coincidences in /sup 252/Cf fission fragments. The experiment was performed with the Argonne-Notre Dame gamma ray facility, which consisted of 7 Compton- suppressed Ge detectors, a low-energy photon spectrometer and an inner ball of fourteen hexagonal BGO detectors. Gamma-gamma coincidence events between the Ge detectors, which were accompanied by a gamma in BGO detectors, were accepted. The triple coincidence requirement eliminated most of the beta-decay background. Transitions in individual Ba and Ce nuclei were identified by gating on the known 2/sup +/ ..-->.. O/sup +/ gamma rays. Level schemes deduced from these studies indicate interleaved negative and positive parity levels in /sup 144/Ba, /sup 146/Ba and /sup 146/Ce which are connected by fast E1 transitions. Both these features are signature of octupole deformation (reflection asymmetric shape) and are reproduced by recent theoretical calculations. 4 refs., 1 fig., 1 tab.

Ahmad, I.; Emling, H.; Holzmann, R.; Janssens, R.V.F.; Khoo, T.L.; Phillips, W.R.; Drigert, M.W.

1989-01-01

326

Spectroscopic studies on proton-rich nucleus ^175Pt  

NASA Astrophysics Data System (ADS)

Neutron-deficient nuclei around the Z=82 shell closure are known to exhibit shape coexsistence, due to the interplay between the occupation of specific intruder orbitals and core effects. It is challenging to study such nuclei experimentally, since fission dominates and, as a consequence, evaporation residue cross sections are small. The Recoil Decay Tagging (RDT) technique combined with the use of a large gamma-ray array is a powerful tool to study such nuclei. ^175Pt was investigated with this approach to clarify the structure of this nucleus and to extend the systematics in this region. Excited states were populated by the ^94Mo(^84Sr,2pn) reaction at beam energies of 380 and 385 MeV provided by ATLAS. Prompt gamma rays were detected by Gammasphere and the recoiling nuclei were identified according to their m/q ratio using the FMA. After m/q identification, the recoiling nuclei were implanted in a 40x40 DSSD, where subsequent charge particle decays were measured. An array of four large-volume Ge detectors and one LEPS detector surrounded the DSSD. The results of this measurement will be presented. This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

Gürdal, G.; Carpenter, M. P.; Kondev, F. G.; Janssens, R. V. F.; Ahmad, I.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Zhu, S.; Hartley, D. J.; Riedinger, L. L.

2010-11-01

327

Spectroscopic studies of swift heavy ion irradiated nanophase mullite  

NASA Astrophysics Data System (ADS)

Photoluminescence (PL) studies of 100 MeV swift Ag 8+ ion bombarded combustion synthesized nanophase mullite has been studied at room temperature (RT) and the results are reported here. A pair of PL bands, one broad band centres at ˜550 nm and another sharp one at ˜690 nm are observed with excitation by a 442 nm laser beam. However, when the sample is excited with 326 nm laser beam, three bands with peaks at ˜460, 550 and a well resolved one with peak at 760 nm are observed. It is observed that the PL intensity increases up to 5 × 10 11 ions/cm 2 and thereafter it decreases with increase of ion fluence. The pristine as well as Ag 8+ ion irradiated mullites are characterized by infrared spectroscopy (IR) and X-ray diffraction (XRD) techniques. The decrease in PL intensity is attributed to Al-O and Si-O bonds present as the surface getting amorphized. The effects of Ag 8+ irradiation are compared to those obtained with Ni 8+ ions and the results are discussed.

Nagabhushana, H.; Lakshminarasappa, B. N.; Prashantha, S. C.; Nagabhushana, K. R.; Singh, Fouran

2006-03-01

328

Sum-frequency spectroscopic studies of ice interfaces  

NASA Astrophysics Data System (ADS)

Sum-frequency vibrational spectroscopy was used to study the (0001) surface of hexagonal ice (Ih) in contact with: air, a hydrophobic substrate, and a hydrophilic substrate. The spectra in the O-H stretch frequency range were obtained at various temperatures. For the air/ice interface, the degree of orientational order of the dangling OH bonds at the surface was measured as a function of temperature. Surface disordering appears to set in around 200 K and increases dramatically with temperature, which is a strong indication of the presence of surface melting of ice. For the hydrophobic and hydrophilic ice interfaces, a similar temperature dependence of the hydrogen-bonded OH stretch peak was observed. The free OH stretch mode, however, appears to be different from that of the air/ice interface due to the interactions with substrates at the interfaces.

Wei, Xing; Miranda, Paulo B.; Zhang, Chun; Shen, Y. R.

2002-08-01

329

Raman spectroscopic study of plasma-treated salmon DNA  

SciTech Connect

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.

Lee, Geon Joon; Kim, Yong Hee; Choi, Eun Ha [Plasma Bioscience Research Center, Kwangwoon University, Seoul 139-701 (Korea, Republic of)] [Plasma Bioscience Research Center, Kwangwoon University, Seoul 139-701 (Korea, Republic of); Kwon, Young-Wan [Department of Chemistry, Korea University, Seoul 136-701 (Korea, Republic of)] [Department of Chemistry, Korea University, Seoul 136-701 (Korea, Republic of)

2013-01-14

330

A spectroscopic study of the blue stragglers in M67  

NASA Astrophysics Data System (ADS)

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).

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

2008-10-01

331

Preparations and spectroscopic studies of organotin complexes of diclofenac*1  

NASA Astrophysics Data System (ADS)

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.

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

2004-08-01

332

Spectroscopic Study of Massive YSO Candidates in the Galactic Center  

NASA Astrophysics Data System (ADS)

The coexistence between extreme environmental conditions (high density, turbulence, magnetic field strengths, and tidal shear) and young massive stars in the Galactic Center has led to one unsolved question: how do stars form in a region which appears to be quite hostile to star birth? Within the central 200 pc, almost all stages of the stellar life cycle have been identified: molecular clouds, HII regions (including compact HII regions), young massive stars, supernova remnants, old red giant and AGB stars. An important class of objects which has yet to be conclusively established and therefore has not been studied, is massive young stellar objects (YSOs). One hundred and seven (107) massive YSO candidates have been identified by Spitzer/IRAC observations in the central 2.0 by 1.4 degrees (280 x 210 pc) of our Galaxy. We propose to observe this sample using the IRS to determine the evolutionary status of these objects. The presence or absence of forbidden emission lines, ice features, and molecular absorptions will determine if these objects are indeed massive YSOs or evolved AGB stars (YSOs and AGB stars have similar IRAC colors). The IRS spectra will be used to constrain the models of the YSOs,which will provide estimates of their stellar masses. The main goal of the study is to determine the distribution of YSOs in the Galactic Center, their correlation with known clusters, ionized gas, molecular gas and photodissociation regions, and their mass distribution. These results will characterize a stellar population that has been undetected before in the central regions of our Galaxy and provide unique knowledge about the early stages of star formation processes occurring in the Galactic Center.

Ramirez, Solange; Arendt, Richard; Cotera, Angela; Robitaille, Thomas; Schultheis, Mathias; Sellgren, Kris; Smith, Howard; Stolovy, Susan

2007-05-01

333

Raman spectroscopic study of ancient South African domestic clay pottery  

NASA Astrophysics Data System (ADS)

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 (?-SiO 2), hematite (?-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.

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

2007-01-01

334

Spectroscopic studies on bilirubin aggregate at liquid/liquid interface.  

PubMed

Bilirubin (BR) aggregating at liquid/liquid interface was firstly detected by Fourier transform infrared (FTIR) imaging/spectroscopy combining with ultraviolet-visible (UV/Vis) absorption spectra. In the UV/Vis absorption spectra of BR aggregate, a new shoulder appeared at 474 nm, and BR absorption maximum underwent red shift from 450 nm to a longer wavelength at 497 nm, which indicates that BR aggregate was formed at the interface. Meanwhile, the BR molecule structure changed or conformation torsion, that is, the increase in orbit overlap or dihedral angle and the enhancement of exciton coupling. In the study of FTIR imaging/spectroscopy, the hydrogen bond-sensitive infrared bands of BR aggregate showed remarkable changes in band shift and intensity compared with those of BR powder, suggesting that the intramolecular hydrogen bonds broke out and internal structure changed. These new findings will be helpful for understanding of the BR molecular interaction, transportation, complex with serum albumin and metal ions, and the effect of BR aggregating on biomembrane and human tissues. PMID:23318764

Xiao, Zhi-Yan; Yin, Jian-Hua

2013-03-01

335

Synchronous fluorescence spectroscopic study of solvatochromic curcumin dye  

NASA Astrophysics Data System (ADS)

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 ? ? = 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 ?SFSmax 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 ?SFSmax vs. ?* scale of solvent polarity was found compared to ?absmax or ?emmax 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.

Patra, Digambara; Barakat, Christelle

2011-09-01

336

Spectroscopic studies on the antioxidant activity of ellagic acid  

NASA Astrophysics Data System (ADS)

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 ?g/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), ?-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, ?-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.

Kilic, Ismail; Ye?ilo?lu, Ye?im; Bayrak, Yüksel

2014-09-01

337

Spectroscopic study of catalysis by zinc chloride of coal depolymerization  

SciTech Connect

Diffuse reflectance infrared spectroscopy was used to monitor in situ reactions which ether groups undergo during the depolymerization of ZnCl/sub 2/-impregnated Wyodak coal at elevated temperatures. Subtraction procedures were used to obtain difference spectra that revealed small changes in IR band intensity between 2000 and 1000 cm/sup /minus/1/. Evidence was obtained indicating that the ZnCl/sub 2/-impregnated coal samples could be depolymerized in an inert argon atmosphere. However, the degree of the cleavage of ether linkages catalyzed by ZnCl/sub 2/ in an inert atmosphere is about 30% of that in a high pressure hydrogen atmosphere (68 atm). The effect of solvent on impregnation of ZnCl/sub 2/ in coal samples was also studied. A higher degree of cleavage of what appears to be a phenyl ether linkage was found for ZnCl/sub 2/-impregnated coal prepared in methanol compared to similar preparations in water and in acetone.

Wang, H.P.; Wann, J.P.; Eyring, E.M.

1988-01-01

338

IR spectroscopic studies of charge transfer in organic semiconductors  

NASA Astrophysics Data System (ADS)

Charge transfer (CT) mechanisms are crucial for device performance in organic electronics, but they are still not understood on a fundamental level. Here we want to show that in situ IR spectroscopy is very well suited to investigate CT effects in organic semiconductors in a qualitative and quantitative way. We study the ambipolar transport material 4,4´-bis(N-carbazolyl)-1,1´-biphenyl (CBP) as matrix and cesium carbonate (Cs2CO3) as n-dopant. To achieve doped layers, both materials were evaporated simultaneously. The system is one of the rare ones for n-doping of organic layers. In the spectra of the doped layers, additional absorption bands appear in the mid IR range. These can be assigned to the negatively charged matrix molecules that indicate electron transfer. The charged molecules exhibit these different absorption bands, as the charge transfer leads to a change in bond length and bond strength of the molecules. Our results very well agree with density functional theory calculations of the vibrational spectra of both, charged and non-charged molecules. By fitting the spectra of the doped layers as a superposition of the vibrational oscillators of neutral and charged species, we were able to quantify the amount of charged matrix molecules and to determine the doping efficiency of the investigated systems. For CBP n-doped with Cs2CO3 a hindrance of the CT due to air exposure could be observed.

Beck, Sebastian; Gerbert, David; Krekeler, Christian; Glaser, Tobias; Pucci, Annemarie

2014-05-01

339

Rotational spectroscopic study of carbonyl sulfide solvated with hydrogen molecules  

NASA Astrophysics Data System (ADS)

Rotational spectra of small-sized (H2)N-OCS clusters with N=2-7 were measured using a pulsed-jet Fourier transform microwave spectrometer. These include spectra of pure (para-H2)N-OCS clusters, pure (ortho-H2)N-OCS clusters, and mixed ortho-H2 and para-H2 containing clusters. The rotational lines of ortho-H2 molecules containing clusters show proton spin-proton spin hyperfine structure, and the pattern evolves as the number of ortho-H2 molecules in the cluster increases. Various isotopologues of the clusters were investigated, including those with O13CS, OC33S, OC34S, and O13C34S. Nuclear quadrupole hyperfine structures of rotational transitions were observed for 33S (nuclear spin quantum number I=3/2) containing isotopologues. The 33S nuclear quadrupole coupling constants are compared to the corresponding constant of the OCS monomer and those of the HeN-OCS clusters. The assignment of the number of solvating hydrogen molecules N is supported by the analyses of the proton spin-proton spin hyperfine structures of the mixed clusters, the dependence of line intensities on sample conditions (pressure and concentrations), and the agreement of the (para-H2)N-OCS and (ortho-H2)N-OCS rotational constants with those from a previous infrared study [J. Tang and A. R. W. McKellar, J. Chem. Phys. 121, 3087 (2004)].

Michaud, Julie M.; Jäger, Wolfgang

2008-10-01

340

UV spectroscopic studies of SBSL bubbles in lithium halides  

NASA Astrophysics Data System (ADS)

As was reported previously, stably levitated bubbles were observed in LiCl and LiBr solutions under SBSL conditions. Stable bubbles were recorded for LiCl concentrations ranging from 0.47 to 1.4 M. Beyond 1.4 M, no SL was detected. In contrast, stable SBSL can be detected over a larger range of LiBr concentrations, from 0.56 to 2.5 M. At 3.0 M, unstable short-lived transient bubbles were noticed. A striking feature common to both salt solutions is the pronounced decrease in SL light intensity, measured with a PMT with peak detection sensitivity at 400 nm, as the salt concentration increases. Light intensities were close to one order of magnitude less than in pure water under similar conditions. The focus of the current study is geared toward resolving the observed reduction in light intensity with respect to chemical processes occurring in the bubble. UV spectroscopy will be key to procuring vital information relating to these processes based on the absorption patterns and the spectral ranges of peak absorptions. Similar salt solutions in D2O, aimed at revealing differences in the chemical processes in the case of heavy water, will also be investigated. [Work supported by a generous grant from University of Washington.

Khong, Anthony; Xu, Ning; Doschek, Elizabeth; Apfel, Robert

2002-05-01

341

Infrared transmission and emission spectroscopic study of selected Chinese palygorskites.  

PubMed

Infrared transmission and emission spectroscopy were used to analyze the difference in structure and thermal behavior of two Chinese palygorskites. The position of the main bands identified in the infrared spectra of the palygorskites studied is similar for these two Chinese samples, but there are some differences in their intensity, which is significant. This discrepancy is attributed to the existence of impurities and the geological environments in different regions. The infrared emission spectra clearly show the structural changes and dehydroxylation of the palygorskites when the temperature is raised. The dehydration of the palygorskites is followed by the loss of intensity of the OH stretching vibration bands in the region of 3600-3200 cm(-1). Dehydroxylation is followed by the decrease in intensity in the bands between 3700 and 3550 cm(-1). Dehydration of pure palygorskite was completed by 600°C. Partial loss of coordinated water was observed at 400°C. Infrared emission spectroscopy is an effective method to determine the stability of the mineral. PMID:21958517

Cheng, Hongfei; Yang, Jing; Frost, Ray L; Wu, Zeguang

2011-12-01

342

A spectroscopic study of laser ablation plasma from Mo target  

NASA Astrophysics Data System (ADS)

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 ?m. 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 ?s 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.

Jakubowska, Katarzyna; Kubkowska, Monika; Blagoev, Alexander; Rosi?ski, Marcin; Parys, Piotr; G?sior, Pawe?

2014-05-01

343

Spectroscopic study of heavy metals sorption on clinoptilolite  

NASA Astrophysics Data System (ADS)

Sorption of heavy metal cations (Pb(II), Cr(III), Cd(II), Ni(II)) from aqueous solutions on natural Na-clinoptilolite was studied using atomic absorption spectrometry (AAS) and FT-IR spectroscopy. It was found that the sorption capacity of clinoptilolite decreases in the following order: Pb(II) (22,600 mg/kg), Cr(III) (21,200 mg/kg), Cd(II) (10,400 mg/kg) and Ni(II) (6,200 mg/kg). In the FT-IR spectra of the samples, in the region of pseudolattice vibrations (500 800 cm-1), systematic changes connected with the type of cation and its concentration in the initial solution were observed. The proportions of ion exchange and chemisorption in the whole process of sorption were also estimated. It was found that the amount of cations sorbed on clinoptilolite depended on the concentrations and pH of the solutions used as well as on the contact time of zeolite-solution system. After 120 min of the reaction, despite the metal type, 90 100% of the total amount of cations were immobilized.

Mozgawa, W.; Bajda, T.

344

Synthesis, growth and vibrational spectroscopic study of a novel coumarinoylthiazole  

NASA Astrophysics Data System (ADS)

An efficient route was developed for the synthesis of novel 3-(2-morpholinyl-4-phenylthiazol-5-oyl)coumarin (MPTC). FT-IR spectrum of MPTC was recorded and analyzed. The crystal structure data are also described. The vibrational wavenumbers were computed theoretically using the Gaussian03 package of programs using HF/6-31G(d) and B3LYP/6-31G(d) levels of theory. The data obtained from vibrational wave number calculations are used to assign vibrational bands observed in the infrared spectra of MPTC. The first hyperpolarizability, infrared absorption band intensities and intensities of raman active bands are reported. The calculated first hyperpolarizability is comparable with the values reported for compounds of similar structure. The structural parameters of MPTC obtained from XRD studies are in agreement with the calculated values. The unit cell parameters of crystals of MPTC are: a = 8.6017(10) Å, b = 9.9735(5) Å, c = 13.3870(13) Å, ? = 111.123(6)°, ? = 90.102(9)°, ? = 110.246(6)°, and Z = 2,1.397 Mg/m3.

Reshmy, R.; Sajan, D.; Kurien Thomas, K.; Sulekha, A.; Rajasekharan, K. N.; Selvanayagam, S.; Alver, Ö.

2012-11-01

345

Spectroscopic studies on the antioxidant activity of ellagic acid.  

PubMed

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 (Fe(2+)) chelating activity and ferric ions (Fe(3+)) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45?g/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), ?-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 (Fe(3+)) reducing power and ferrous ions (Fe(2+)) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, ?-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. PMID:24813273

Kilic, Ismail; Ye?ilo?lu, Ye?im; Bayrak, Yüksel

2014-09-15

346

Electron spin resonance spectroscopic studies of radical cation reactions  

SciTech Connect

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

Dai, S.

1990-01-01

347

Spectroscopic study of the interaction of pazelliptine with nucleic acids.  

PubMed

The antitumor drug pazelliptine (PZE) binds to natural and synthetic DNA sequences at 100 mM NaCl, pH 7.0, as deduced from the absorption and fluorescence data. Scatchard plots constructed from the results obtained with poly(dG-dC)-poly(dG-dC) give binding constants of base pairs in the range (2-6) x 10(5)M(-1). The modifications in the absorption and fluorescence spectra observed when PZE binds to various polynucleotides, namely poly(dA-dT)-poly(dA-dT), poly(dA)-poly(dT), poly(dG-dC)-poly(dG-dC) and calf thymus DNA, reveal a change in the protonation state of the drug upon binding, increasing the apparent pKa of its 9-N-nitrogen atom. The PZE excited state properties serve as a sensitive probe to distinguish between homo and hetero A-T sites as well as between AT and GC sites. Fluorescence studies reveal that energy transfer occurs from polynucleotide bases to the bound PZE chromophore, a result consistent with an intercalative mode of binding of the drug to DNA. The emission is enhanced when PZE is bound to A-T base pairs (approximately 30% increase of phi(F) whereas it is quenched in the vicinity of G-C base pairs (approximately 90% decrease of phi(F)). Furthermore, the fluorescence spectrum obtained with calf thymus DNA is hardly distinguishable from that obtained with poly(dG-dC)-poly(dG-dC), suggesting a binding of PZE to G-C rich regions. PMID:9463113

Renault, E; Fontaine-Aupart, M P; Tfibel, F; Gardes-Albert, M; Bisagni, E

1997-10-01

348

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

NASA Astrophysics Data System (ADS)

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 rôle 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 rôle 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 ion-induced dipole collisions with the bound electrons. The ions are thus important in randomising and equilibrating the velocity distribution of atomic products of molecular dissociation.

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

2006-12-01

349

Spectroscopic studies on alpha particle-irradiated PADC (CR-39 detector)  

NASA Astrophysics Data System (ADS)

Spectroscopic studies on a Poly Allyl Diglycol Carbonate (PADC or CR-39) detector irradiated with 5 MeV ?-particles were carried out. The CR-39 samples were exposed to perpendicular incidence of ?-particles with different fluence ranging from 0.85 × 109 to 6.79 × 109 particles/cm2. The induced modifications in the CR-39 detectors were investigated using UV-Vis, FTIR, and photoluminescence (PL) spectroscopy. The results reveal that UV-Visible and FTIR spectroscopic techniques are insensitive to detect the induced modifications in the irradiated CR-39 detector within the selected range of fluence. Photoluminescence (PL) spectra, on the other hand, showed a reasonable difference between the detected spectra of the irradiated samples. The integrated intensity (N) under the PL emission band and peak’s heights (P) exhibits a linear correlation with the alpha particles fluence. The fitting linear formula and the relevant parameters for both relations (N and P vs. fluence) were determined. The comparison study between the three spectroscopic techniques indicated that PL spectroscopy provides a sensitive method for ?-particles dosimetric applications using a CR-39 detector.

El Ghazaly, M.; Hassan, H. E.

350

Spectroscopic analysis of radiation-generated changes in tensile properties of a polyetherimide film  

NASA Technical Reports Server (NTRS)

The effects of electron radiation on Ultem, a polyetherimide were studied for doses from 2 x 10 to the 9th power to 6 x 10 to the 9th power rad. Specimens were studied for tensile property testing and for electron paramagnetic resonance and infrared spectroscopic measurements of molecular structure. A Faraday cup design and a method for remote temperature measurement were developed. The spectroscopic data show that radiation caused dehydrogenation of methyl groups, rupture of main-chain ether linkage, and opening of imide rings, all to form radicals and indicate that the so-formed atomic hydrogen attached to phenyl radicals, but not to phenoxyl radicals, which would have formed hydroxyls. The observed decays of the radiation-generated phenoxyl, gem-dimethyl, and carbonyl radicals were interpreted as a combining of the radicals to form crosslinking. This crosslinking is the probable cause of the major reduction in the elongation of the tensile specimens after irradiation. Subsequent classical solubility tests indicate that the irradiation caused massive crosslinking.

Long, E. R., Jr.; Long, S. A. T.

1985-01-01

351

Synthesis, structure, and fluxional behavior of octahedral ruthenium(II) complexes with mixed oxygen-phosphine ligands. [sup 31]P DNMR spectroscopic studies, line shape analysis, and determination of rearrangement barriers  

SciTech Connect

The synthesis and spectroscopic properties of ether-phosphine ruthenium(II) complexes of the type Cl[sub 2]Ru([cflx P O])[sub 2] (5a, 7a-10a) and trans-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (5b, 7b-10b) are reported. Temperature-dependent [sup 31]P NMR spectra of the fluxional complexes 1b-11b and cis-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (1c-3c) were measured and by using a modified version of DNMR5, computer-generated spectra were obtained and fitted to the experimental spectra. Graphic application of the Eyring equation to the kinetic data afforded the thermodynamic parameters [Delta]H[double dagger], [Delta]S[double dagger], and [Delta]G[double dagger]. Complex 11b with the strong basic four-membered ether-phosphine 11 crystallizes in the monoclinic space group P2[sub 1]/n, with a = 11.974(2) [Angstrom], b = 10.877(2) [Angstrom], c = 29.567(6) [Angstrom], [beta] = 96.34(3)[degrees], Z = 4, and V = 3827.2(12) [Angstrom][sup 3] (R = 0.075 and R[sub w] = 0.076). 33 refs., 4 figs., 4 tabs.

Lindner, E.; Moeckel, A.; Mayer, H.A.; Kuehbauch, H.; Fawzi, R.; Steimann, M. (Inst. fuer Anorganische Chemie der Universitaet, Tuebingen (Germany))

1993-03-31

352

A Neutron Spectroscopic Study of the Diffusive Kinetics and Interactions of Water in Dense Layer Desalination Membranes.  

National Technical Information Service (NTIS)

Neutron spectroscopic investigations were carried out to systematically study and determine, at a molecular level, the factors and properties that control the diffusion and bonding of water in 'dense skin' cellulose-acetate desalination membranes. Data we...

G. J. Safford P. S. Leung

1972-01-01

353

[FT-IR spectroscopic analysis in monitoring of hydroxyl stretching vibrations in plant hydrogels].  

PubMed

In recent years, some bioactive hydrogels isolated from natural sources have attracted much attention in the field of biochemistry and pharmacology. This article attempts to review the current structural and conformational characterization of some importantly bioactive hydrogels isolated from following plant: Symphytum officinale, Thymus pulegioides, Trigonella foenum-graecum L., Tussilago farfara L., Hyssopus officinalis, Althaea officinalis L., Equisetum arvense L. Linum usitatissimum L. and Fucus vesiculosus L. Hydrogels are cross-linked three-dimensional polysaccharide macromolecular networks that contain a large fraction of water within their structure. FT-IR spectroscopic analysis showed a strong band at 3500-3100 cm(-1) attributed to hydroxyl (the intermolecular and the intramolecular hydrogen bonds) stretching vibrations changes. PMID:22332324

Pielesz, Anna; Binia?, Dorota; Wieczorek, Joanna

2011-01-01

354

Synthesis and spectroscopic characterization of copper(II) tetraazaiminooxime macrocyclic complexes—A tetragonal distortion analysis  

Microsoft Academic Search

Herein we describe the synthesis and spectroscopic (infrared and UV–vis) analysis of [CuII(dohpn)(L)]n+ (dohpn=imineoximic tetraazamacrocyclic ligand 2,3,9,10-tetramethyl-1,4,8,11-tetraazaundecane-1,3,8,10-tetraen-11-ol-1-olate) and L=SCN?, I?, Cl? (n=0) and 4-aminopyridine (ampy), 4,4?-bipyridine (bipy), imidazole (im), 2-aminopyrazine (ampz) and water (n=1+). The following order of the Jahn-Teller stabilization energy (cm?1) was observed: I?(6452)

Gisele Marina Protasiewyck; Fábio Souza Nunes

2006-01-01

355

Synthesis and spectroscopic characterization of copper(II) tetraazaiminooxime macrocyclic complexes—A tetragonal distortion analysis  

NASA Astrophysics Data System (ADS)

Herein we describe the synthesis and spectroscopic (infrared and UV-vis) analysis of [Cu II(dohpn)(L)] n+ (dohpn = imineoximic tetraazamacrocyclic ligand 2,3,9,10-tetramethyl-1,4,8,11-tetraazaundecane-1,3,8,10-tetraen-11-ol-1-olate) and L = SCN -, I -, Cl - ( n = 0) and 4-aminopyridine (ampy), 4,4'-bipyridine (bipy), imidazole (im), 2-aminopyrazine (ampz) and water ( n = 1+). The following order of the Jahn-Teller stabilization energy (cm -1) was observed: I -(6452) < Cl -(6477) < NCS -(6494) < ampy(6562) < im(6614) < bipy(6685) < ampz(6739) < H 2O(7813) and the energy of the crystal field transition was correlated with the tetragonal distortion in the structures.

Protasiewyck, Gisele Marina; Nunes, Fábio Souza

2006-11-01

356

Data processing method applying principal component analysis and spectral angle mapper for imaging spectroscopic sensors  

NASA Astrophysics Data System (ADS)

A data processing method for hyperspectral images is presented. Each image contains the whole diffuse reflectance spectra of the analyzed material for all the spatial positions along a specific line of vision. This data processing method is composed of two blocks: data compression and classification unit. Data compression is performed by means of Principal Component Analysis (PCA) and the spectral interpretation algorithm for classification is the Spectral Angle Mapper (SAM). This strategy of classification applying PCA and SAM has been successfully tested on the raw material on-line characterization in the tobacco industry. In this application case the desired raw material (tobacco leaves) should be discriminated from other unwanted spurious materials, such as plastic, cardboard, leather, candy paper, etc. Hyperspectral images are recorded by a spectroscopic sensor consisting of a monochromatic camera and a passive Prism- Grating-Prism device. Performance results are compared with a spectral interpretation algorithm based on Artificial Neural Networks (ANN).

García-Allende, P. B.; Conde, O. M.; Mirapeix, J.; Cubillas, A. M.; López-Higuera, J. M.

2007-07-01

357

Spectroscopic Analysis of Nd^3+:Y2O3 Nanocrystals for Photonic and Biomedical Applications  

NASA Astrophysics Data System (ADS)

Spectroscopic properties are investigated for Nd^3+ in nanocrystalline Nd^3+:Y2O3. Room temperature absorption intensities of Nd^3+(4f^3) transitions in synthesized Nd^3+:Y2O3 nanocrystals have been analyzed using the Judd-Ofelt (J-O) approach in order to obtain the phenomenological intensity parameters. The J-O intensity parameters are used to calculate the spontaneous emission probabilities, radiative lifetimes, and branching ratios of the Nd^3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds ^2S+1LJ of Nd^3+(4f^3). A comparison between the spectroscopic properties of the Nd^3+ nanocrystals suspended in epoxy, Chitosan, and 2-hydoxyethyl methacrylate (HEMA) has been performed. This study suggests that synthesized Nd^3+:Y2O3 nanocrystals could be an excellent alternative to single-crystal Ho^3+:Y2O3 for various photonic applications, in particularly biosensors, when used in the near infrared (0.8 to 0.9 ?m ) region. *This research was supported in part by the National Science Foundation Grant No. DMR-0602649 and the NSF-sponsored CBST at UC Davis under the cooperative agreement No. PHY-0120999.

Dennis, Robert C.; Nash, Kelly L.; Gruber, John B.; Sardar, Dhiraj K.

2008-03-01

358

The Spectroscopic and Photometric Analysis of the Eclipsing Binary System DN UMa  

NASA Astrophysics Data System (ADS)

The eclipsing binary system DN UMa (HD 103483) is a likely triple system with a possible pulsating component that has been studied extensively. The period of 1.7-d has been determined by Gimenez and Queseda (1982). Wilson (1953) reported a systemic radial velocity of -8 km/s, based on a limited data-set. To investigate this interesting object further, we initiated a photometric campaign in April 2009 on the Automatic Photoelectric Telescope in Patagonia, AZ. In January 2010 we followed up DN UMa spectroscopically at the 2.1 m telescope at Kitt Peak National Observatory. The high-resolution echelle spectra have been processed in IRAF. The exposures have been cleaned of cosmic rays, and the extracted spectra have been wavelength-calibrated and flux-normalized. In conjunction with photometry, the spectroscopic data were used to determine fundamental parameters (radii, masses, and temperatures) of the binary star components. We present the results of the modeling based on archival and newly acquired data.

Robertson, Jordan; Prsa, A.; Kirk, B.; Engle, S.

2011-01-01

359

Studies on the binding behavior of prodigiosin with bovine hemoglobin by multi-spectroscopic techniques  

NASA Astrophysics Data System (ADS)

In this article, the interaction mechanism of prodigiosin (PG) with bovine hemoglobin (BHb) is studied in detail using various spectroscopic technologies. UV-vis absorption and fluorescence spectra demonstrate the interaction process. The Stern-Volmer plot and the time-resolved fluorescence study suggest the quenching mechanism of fluorescence of BHb by PG is a static quenching procedure, and the hydrophobic interactions play a major role in binding of PG to BHb. Furthermore, synchronous fluorescence studies, Fourier transform infrared (FTIR) and circular dichroism (CD) spectra reveal that the conformation of BHb is changed after conjugation with PG.

Tang, Jing; Yang, Chao; Zhou, Lin; Ma, Fei; Liu, Shuchao; Wei, Shaohua; Zhou, Jiahong; Zhou, Yanhuai

2012-10-01

360

Studies on the binding behavior of prodigiosin with bovine hemoglobin by multi-spectroscopic techniques.  

PubMed

In this article, the interaction mechanism of prodigiosin (PG) with bovine hemoglobin (BHb) is studied in detail using various spectroscopic technologies. UV-vis absorption and fluorescence spectra demonstrate the interaction process. The Stern-Volmer plot and the time-resolved fluorescence study suggest the quenching mechanism of fluorescence of BHb by PG is a static quenching procedure, and the hydrophobic interactions play a major role in binding of PG to BHb. Furthermore, synchronous fluorescence studies, Fourier transform infrared (FTIR) and circular dichroism (CD) spectra reveal that the conformation of BHb is changed after conjugation with PG. PMID:22728237

Tang, Jing; Yang, Chao; Zhou, Lin; Ma, Fei; Liu, Shuchao; Wei, Shaohua; Zhou, Jiahong; Zhou, Yanhuai

2012-10-01

361

October 24 - 25, 2005:MR Spectroscopic Analysis of Tumour Metabolic Phenotype Changes in Response to Therapy, Risto A. Kauppinen  

Cancer.gov

MR Spectroscopic Analysis of Tumour Metabolic Phenotype Changes in Response to Therapy Risto A. Kauppinen University of Birmingham U.K. R.A.Kauppinen@bham.ac.uk 2 NAA Cr Cho Cr Glx Tau Myo-ins Glx/NAA Myo-ins MM/ Lip/ Lac 2 PPM 3 4 1 0 5 Rat brain LASER TR

362

Micro-Raman spectroscopic study of nanolaminated Ti5Al2C3  

NASA Astrophysics Data System (ADS)

Micro-Raman spectroscopic study and lattice dynamics calculations were conducted to study a recently identified layered ternary carbide, Ti5Al2C3. The experimental Raman shifts were remarkably consistent with the calculated values. Polarized Raman spectrum was collected in the polycrystalline sample, which confirmed the theoretical symmetry assignment of the Raman modes. In addition, the atomic vibrations of the peaks at 192 cm-1, 311 cm-1, and 660 cm-1 were identified to be the combination of the counterparts in Ti2AlC and Ti3AlC2.

Zhang, H.; Wang, X. H.; Xiang, H. M.; Li, Z. J.; Zhou, Y. C.

2014-03-01

363

Synthesis, growth, structural, spectroscopic, crystalline perfection, second harmonic generation (SHG) and thermal studies of 2-aminopyridinium picrate (2APP): A new nonlinear optical material  

NASA Astrophysics Data System (ADS)

Single crystal growth, spectroscopic, relative second harmonic generation (SHG) efficiency and thermal analysis of 2-aminopyridinium picrate (2APP) is reported for the first time. Crystals were grown by the slow evaporation solution technique using methanol as a solvent. The crystal system and lattice parameters were confirmed by single crystal and powder XRD analyses. FT-IR and FT-Raman spectroscopic studies were carried out to identify the functional groups and vibrational modes present in the grown crystal. Crystalline perfection of the grown crystal was assessed by high-resolution XRD and the results reveal that the crystal is reasonably good. SHG efficiency was measured using Kurtz powder technique. Thermogravimetric (TG) and differential thermal analysis (DTA) studies were carried out and show that the grown single crystal is stable up to 223 °C.

Shkir, Mohd.; Riscob, B.; Bhagavannarayana, G.

2012-07-01

364

Spectroscopic analysis of titanium surface functional groups under various surface modification and their behaviors in vitro and in vivo.  

PubMed

In the present study, surface functional groups of titanium surfaces gone through different treatments, including acid etched treatment (AE), nitric acid treatment (NT), heat treatment (HT), and alkali treatment (AT), and their behaviors in vitro and in vivo was thoroughly studied by spectroscopic analysis. In vitro and in vivo results revealed that the rank of bioactivity of various surfaces was AE < NT < HT < AT. XPS analysis indicated that AT greatly increased the OH group concentration on the titanium surface whereas HT reduced the OH group concentration. Thus, OH group difference could not be a good explanation of bioactivity difference. On the other hand, ToF-SIMS analysis demonstrated the TiOH+/Ti+ ratios of various surfaces correlated well with the bioactivity and the surface energies, which implied that Ti-OH could play an important role in the bioactivity. This detail investigation of the relationship between surface functional groups and surface bioactivity could help us to broaden the knowledge about the mechanism of bioactivity and to design next generation bioactive materials. PMID:17618503

Lu, Xiong; Wang, Yingbo; Yang, Xiudong; Zhang, Qiyi; Zhao, Zhanfeng; Weng, Lu-Tao; Leng, Yang

2008-02-01

365

Influence of the real-life structures in optical metrology using spectroscopic scatterometry analysis  

NASA Astrophysics Data System (ADS)

During the last five years scatterometry measurement using ellispometry and reflectometry has met a great interest in nano and microelectronics fab. Today, this technology of measurement is used to control lot production and has become mature for 1D-grating measurements. Nevertheless, some aspects of this method of measurement are always under research studies. This paper focuses on one of these aspects: the evaluation of the influence of the "real-life 1D-structure" (linewidth variations along the lines and line to line, roughness, defect inside the grating) on spectroscopic signatures and on scatterometry measurement methods. The measurements have been carried out on KLA-TENCOR ellispometer and on Nanometrics reflectometer in order to compare the two methods of measurement. The simulations have been done with MMFE (Modal Method of Fourier Expansion) software developed by LETI labs. To control defect characteristics and defect distributions, one wafer was printed using electron beam lithography. The aim is the evaluation of the impact of defects in the grating on the spectroscopic signatures and its influence on extracted geometrical parameters by fitting the experimental curves. Different deviations to real-life structures have been studied. First we focus on the influence of typical defects of lithography processes such as bridging and partial destruction of lines and on the influence of CD distribution values inside the grating. Then, we study the influence and the possibilities of measuring Line Edge Roughness (LER). For LER measurements different targets have been also exposed on e-beam tool. Simulations and experimental measurements have been carried out. All the results obtained have been compared with imaging standard tool: top down SEM measurement.

Quintanilha, R.; Hazart, J.; Thony, P.; Henry, D.

2005-08-01

366

Spectroscopic analysis on the resveratrol-DNA binding interactions at physiological pH  

NASA Astrophysics Data System (ADS)

The interaction of resveratrol with calf thymus deoxyribonucleic acid (ctDNA) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) was studied by spectroscopy, fluorescence spectroscopy and viscosity measurement method, respectively. Results indicated that a complex of resveratrol with ctDNA was formed with a binding constant of K17 °C = 5.49 × 10 3 L mol -1 and K37 °C = 1.90 × 10 4 L mol -1. The fluorescence quenching mechanism of acridine orange (AO)-ctDNA by resveratrol was shown to be a static quenching type. The thermodynamic parameters of the complex were calculated by a double reciprocal method: ?Hms=4.64×10 J mol, ?Sms=231.8 J K mol and ?Gms=-2.54×10 J mol (37 °C). Spectroscopic techniques together with viscosity determination provided evidences of intercalation mode of binding for the interaction between resveratrol and ctDNA.

Zhang, Shufang; Sun, Xuejun; Jing, Zhihong; Qu, Fengli

2011-11-01

367

Spectroscopic ellipsometry analysis of silicon nanotips obtained by electron cyclotron resonance plasma etching.  

PubMed

Silicon nanotips fabricated by electron cyclotron resonance plasma etching of silicon wafers are studied by spectroscopic ellipsometry. The structure of the nanotips is composed of columns 100-140 nm wide and spaced by about 200 nm. Ellipsometry data covering a wide spectral range from the midinfrared to the visible are described by modeling the nanotip layer as a graded uniaxial film using the Bruggeman effective medium approximation. The ellipsometry data in the infrared range reveal two absorption bands at 754 and 955 cm(-1), which cannot be resolved with transmittance measurements. These bands indicate that the etching process is accompanied with formation of carbonaceous SiC and CH(n) species that largely modify the composition of the original crystalline silicon material affecting the optical response of the nanotips. PMID:19745863

Mendoza-Galván, Arturo; Järrendahl, Kenneth; Arwin, Hans; Huang, Yi-Fan; Chen, Li-Chyong; Chen, Kuei-Hsien

2009-09-10

368

Spectroscopic studies of interaction between biologically synthesized silver nanoparticles and bovine serum albumin.  

PubMed

Binding interaction of biologically synthesized silver nanoparticles with bovine serum albumin (BSA) has been investigated by UV-Vis and fluorescence spectroscopic techniques. UV-Vis analysis implies the formation of the ground state complex between BSA and silver nanoparticles. The analysis of fluorescence spectrum and fluorescence intensity indicates that silver nanoparticles (SNP) have a strong ability to quench the intrinsic fluorescence of BSA by dynamic quenching mechanisms. The number of binding sites 'n' and binding constants 'K' were determined at different temperatures based on fluorescence quenching. The thermodynamic parameters namely deltaH, deltaG, and deltaS were calculated at different temperatures (20, 30, and 40 degrees C) and the results indicate that both hydrophobic and electrostatic interactions were predominantly present in the SNP-BSA complex. Negative deltaG values imply that the binding process is spontaneous. PMID:24757960

Roy, Swarup; Das, Tapan Kumar

2014-07-01

369

Optical characteristics of pulsed laser deposited Ge-Sb-Te thin films studied by spectroscopic ellipsometry  

SciTech Connect

Pulsed laser deposition technique was used for the fabrication of (GeTe){sub 1-x}(Sb{sub 2}Te{sub 3}){sub x} (x = 0, 0.33, 0.50, 0.66, and 1) amorphous thin films. Scanning electron microscopy with energy-dispersive x-ray analysis, x-ray diffraction, optical reflectivity, and sheet resistance temperature dependences as well as variable angle spectroscopic ellipsometry measurements were used to characterize as-deposited (amorphous) and annealed (rocksaltlike) layers. In order to extract optical functions of the films, the Cody-Lorentz model was applied for the analysis of ellipsometric data. Fitted sets of Cody-Lorentz model parameters are discussed in relation with chemical composition and the structure of the layers. The GeTe component content was found to be responsible for the huge optical functions and thickness changes upon amorphous-to-fcc phase transition.

Nemec, P. [Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Prikryl, J.; Frumar, M. [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice (Czech Republic); Nazabal, V. [Equipe Verres et Ceramiques, UMR-CNRS 6226, Sciences Chimiques de Rennes (SCR), Universite de Rennes 1, 35042 Rennes Cedex (France)

2011-04-01

370

Quantitative carbon-13 nuclear magnetic resonance spectroscopic study of mobile residues in bacteriorhodopsin  

SciTech Connect

The authors have used quantitative carbon-13 nuclear magnetic resonance (NMR) spectroscopy to study the dynamic structure of the backbone of bacteriorhodopsin in the purple membrane of Halobacterium halobium R/sub 1/ and JW-3. NMR experiments were performed using an internal sucrose quantitation standard on purple membranes in which one of the following /sup 13/C'-labeled amino acids had been biosynthetically incorporated: glycine, isoleucine, lysine, phenylalanine, and valine. The results suggest that the C-terminus of the polypeptide chain backbone, and possibly one of the connecting loops, undergoes rapid, large angle fluctuations. The results are compared with previous NMR and fluorescence spectroscopic data obtained on bacteriorhodopsin.

Bowers, J.L.; Oldfield, E.

1988-07-12

371

HeI photoelectron spectroscopic studies on the electronic structure of alkyl nitrosamines  

NASA Astrophysics Data System (ADS)

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.

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

1997-10-01

372

Conformation of a MnCp(CO)2-thienothiophene carbene complex: A spectroscopic and computational study  

NASA Astrophysics Data System (ADS)

The carbene complex [MnCp(CO)2C(OEt)(TT)], (TT = 3,6-dimethylthieno[3,2-b]thiophene) 1, was synthesized according to the classical Fischer method. The novel complex was fully characterized using various spectroscopic techniques. The infrared spectrum of the complex, recorded as a solution in dichloromethane, revealed a four-band spectrum in the carbonyl region instead of the expected two-band spectrum. A density functional theory (DFT) study was undertaken to explain the presence of more than one conformer in solution. The crystal structure of 1 is reported.

Landman, Marilé; Barnard, Werner; van Rooyen, Petrus H.; Liles, David C.

2012-08-01

373

Spectroscopic study of Nd 3+\\/Yb 3+ in disordered potassium bismuth molybdate laser crystals  

Microsoft Academic Search

In this work we report the study of energy transfer between Nd3+ and Yb3+ ions in disordered K5Bi1?x?yNdxYby(MoO4)4 crystals (x=0.01, 0.05, 0.1, 0.15, 0.2 and y=0.1) at room temperature by using steady-state and time-resolved laser spectroscopy. The spectroscopic properties of Nd3+ and Yb3+ ions in these crystals make them suitable for efficient energy transfer because of the energy gap between

R. Balda; J. Fernández; I. Iparraguirre; M. Al-Saleh

2006-01-01

374

Spectroscopic study of hydrogen particle behavior in attached and detached divertor plasmas of JT-60U  

NASA Astrophysics Data System (ADS)

Hydrogen particle behavior, especially H 2 molecule behavior, has been studied spectroscopically in attached and detached divertor plasmas of JT-60U. The decay lengths of the H 2 Fulcher line intensity in attached and detached divertor plasmas were roughly 1 cm and 4 cm, respectively. The fall in intensity of the H 2 Fulcher lines with distance from the divertor plates was reproduced by calculation using a neutral transport and a collisional radiative model code. Molecular assisted recombination was estimated to be as important as H +-e recombination in a detached divertor plasma.

Kubo, H.; Takenaga, H.; Sawada, K.; Nakano, T.; Kobayashi, S.; Higashijima, S.; Asakura, N.; Shimizu, K.

2005-03-01

375

Fourier transform Raman spectroscopic studies of encrustations formed at the lichen-substratum interface  

NASA Astrophysics Data System (ADS)

FT-Raman microscope spectra of lichen-substratum samples of Xanthoria parietina and Ochrolechia parella growing in situ on sandstone have been obtained. The presence of small amounts of calcium oxalate and evidence for biodeterioration by lichen metabolic by-products is confirmed spectroscopically. Comparisons are made with similar studies of aggressive colonization by the high oxalate-producing lichen Dirina massiliensis forma sorediata on Renaissance frescoes. Spatial discrimination of the Raman microprobe technique for high and low oxalate-producing lichens is demonstrated.

Edwards, Howell G.; Farwell, Dennis W.; Lewis, Ian R.; Seaward, Mark R.

1994-01-01

376

Thermodynamic and spectroscopic studies of cadmium(II)– N-(phosphonomethyl)glycine (PMG) complexes  

Microsoft Academic Search

Speciation and equilibria in the H+–Cd2+–N-(phosphonomethyl)glycine (PMG, H3L) system have been studied in 0.1 M Na(Cl) medium at 25.0 °C. Formation constants for a series of mononuclear complexes, CdHL, CdL?, CdL24? and CdL(OH)2? were determined from potentiometric titrations. The structures of the predominating species CdL?, and CdL24? in solution were investigated using EXAFS and IR spectroscopic techniques. In the 1:1

Madeleine Ramstedt; Caroline Norgren; Julia Sheals; Dan Boström; Staffan Sjöberg; Per Persson

2004-01-01

377

Critical evaluation of spectroscopic indices for organic matter source tracing via end member mixing analysis based on two contrasting sources.  

PubMed

Despite the wide use of absorption and fluorescence spectroscopy for tracking the sources of dissolved organic matter (DOM), there are limited studies on evaluating their source discrimination capabilities at variable solution chemistry (pH, NaCl, Ca(2+), and DOM concentration). For this study, we compared the applicability of several well-known spectroscopic indices via end member mixing analysis based on two contrasting DOM sources (Suwannee River fulvic acid and an algal DOM). The absorption coefficients and the intensities of fluorescent components from parallel factor analysis (PARAFAC) showed linear relationships with increasing algal carbon fraction in the mixture of the two DOMs. In contrast, although they still behaved conservatively, spectral ratio indices such as spectral slopes, ratios of PARAFAC components, humification index, and fluorescence index changed in nonlinear patterns with the mixing ratios. The indices based on PARAFAC results exhibited strong discrimination capabilities, as indicated by high susceptibility to the changes in DOM sources relative to the analytical precision. While variable NaCl concentrations had limited effects, most fluorescence indices were considerably affected by other solution chemistry such as pH, Ca(2+), and DOM level. Our study demonstrated that the applicability of the source discrimination indices should be critically examined especially in the environments with notable changes in the solution chemistry. The solution chemistry effects could be minimized by adjusting samples to a constant condition prior to the measurements or otherwise the effects should be fully taken into account in interpreting the field observations. PMID:24784456

Yang, Liyang; Hur, Jin

2014-08-01

378

Infrared and Raman spectroscopic studies on alkali borate glasses: evidence of mixed alkali effect.  

PubMed

A lithium-potassium-borate glass system containing manganese and iron cations has been thoroughly investigated in order to obtain information about the mixed alkali effect and the structural role of both the manganese and iron in such glass hosts. Mixed alkali borate glasses of the (30 - x)Li(2)O - xK(2)O - 10CdO/ZnO - 59B(2)O(3) (x = 0, 10, 15, 20, and 30) doped with 1MnO(2)/1Fe(2)O(3) system were prepared by a melt quench technique. The amorphous phase of the prepared glass samples was confirmed from their X-ray diffraction. The spectroscopic properties of glass samples were studied using infrared (IR) and Raman spectroscopic techniques. The density of all the prepared glasses was measured using Archimedes principle. Molar volumes were estimated from the density data. IR spectra of these glasses revealed a dramatic variation of three- and four-coordinated boron structures as a function of mixed alkali concentration. The vibrations due to Li-O, K-O, and MnO(4)/FeO(4) arrangements are consistent in all the compositions and show a nonlinear variation in the intensity with alkali content. Raman spectra of different alkali combinations with CdO and ZnO present drastic changes in the intensity of various Raman bands. The observation of disappearance and reappearance of IR and Raman bands as a function of various alkali concentrations is an important result pertaining to the mixed alkali effect in borate glasses. Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO(3) and BO(4) units placed in different structural groups, the BO(3) units being dominant. The measured IR and Raman spectra of different glasses are used to clarify the optical properties of the present glasses correlating them with their structure and composition. PMID:19235995

Padmaja, G; Kistaiah, P

2009-03-19

379

Raman micro-spectroscopic analysis of cultured HCT116 colon cancer cells in the presence of roscovitine  

NASA Astrophysics Data System (ADS)

Raman micro-spectroscopic analysis of cultured HCT116 colon cancer cells in the presence of roscovitine, [seliciclib, 2-(1-ethyl-2-hydroxy-ethylamino)-6-benzylamino-9-isopropylpurine], a promising drug candidate in cancer therapy, has been performed for the first time. The aim of this study was to investigate modulations in colon cancer cells induced by roscovitine. Raman spectra of the cultured HCT116 colon cancer cells treated with roscovitine at different concentrations (0, 5, 10, 25 and 50 ?M) were recorded in the range 400-1850 cm -1. It was shown that the second derivative profile of the experimental spectrum gives valuable information about the wavenumbers and band widths of the vibrational modes of cell components, and it eliminates the appearance of false peaks arising from incorrect baseline corrections. In samples containing roscovitine, significant spectral changes were observed in the intensities of characteristic protein and DNA bands, which indicate roscovitine-induced apoptosis. Roscovitine-induced apoptosis was also assessed by flow cytometry analysis, and analysis of propidium iodide staining. We observed some modifications in amide I and III bands, which arise from alterations in the secondary structure of cell proteins caused by the presence of roscovitine.

Akyuz, S.; Ozel, A. E.; Balci, K.; Akyuz, T.; Coker, A.; Arisan, E. D.; Palavan-Unsal, N.; Ozalpan, A.

2011-05-01

380

Spectroscopic and TSDC analysis of 100 MeV Ag ion irradiated polyetherimide  

NASA Astrophysics Data System (ADS)

The energetic heavy ion irradiation effects in polymers have drawn considerable attention for the application of polymers in radioactive environment. In the present paper, we report the Fourier transform infrared (FTIR) and UV-visible spectroscopic analysis and thermally stimulated depolarization current (TSDC) investigations in polyetherimide (PEI) samples (25 ?m) irradiated with 100 MeV Ag ion at different fluences (5.6×1010, 1.8×1011, 1.8×1012 ions/cm2). The FTIR spectra of irradiated samples show an overall decrease in the intensity of all the typical bands, whereas the UV-visible spectra show a hyperchromic and bathochromic shift attributed to the formation of new defect sites. The radiation induced dehydrogenation of the methyl pendent group, opening of imide rings and the formation of carbonyl radicals and unsaturated C = C bonds are the major conclusion drawn from the FTIR analysisE The TSDC spectra of pristine PEI comprises two current maxima termed as ?- and ?-peak with their respective locations around 80° and 190 °C. These are attributed to dipole-orientation and space charge relaxation, respectively. A significant effect of irradiation is observed on the whole TSDC spectrum. The ?-peak vanishes due to demerization of carbonyl groups. Enhancement in the ?-peak has been associated to the formation of new deep traps. Some new radiation induced relaxation processes have also been identified.

Goyal, Geetika; Garg, Maneesha; Quamara, J. K.

381

Spectroscopic analysis of DA white dwarfs with 3D model atmospheres  

NASA Astrophysics Data System (ADS)

We present the first grid of mean three-dimensional (3D) spectra for pure-hydrogen (DA) white dwarfs based on 3D model atmospheres. We use CO5BOLD radiation-hydrodynamics 3D simulations instead of the mixing-length theory for the treatment of convection. The simulations cover the effective temperature range of 6000 < Teff (K) < 15 000 and the surface gravity range of 7 < log g < 9 where the large majority of DAs with a convective atmosphere are located. We rely on horizontally averaged 3D structures (over constant Rosseland optical depth) to compute ?3D? spectra. It is demonstrated that our ?3D? spectra can be smoothly connected to their 1D counterparts at higher and lower Teff where the 3D effects are small. Analytical functions are provided in order to convert spectroscopically determined 1D effective temperatures and surface gravities to 3D atmospheric parameters. We apply our improved models to well studied spectroscopic data sets from the Sloan Digital Sky Survey and the White Dwarf Catalog. We confirm that the so-called high-log g problem is not present when employing ?3D? spectra and that the issue was caused by inaccuracies in the 1D mixing-length approach. The white dwarfs with a radiative and a convective atmosphere have derived mean masses that are the same within ~0.01 M?, in much better agreement with our understanding of stellar evolution. Furthermore, the 3D atmospheric parameters are in better agreement with independent Teff and log g values from photometric and parallax measurements. Appendices are only available in electronic form at http://www.aanda.org

Tremblay, P.-E.; Ludwig, H.-G.; Steffen, M.; Freytag, B.

2013-11-01

382

Spectroscopic studies on chemical- and photo-responsive molecular machines and their bio-applications  

NASA Astrophysics Data System (ADS)

The four chapters presented in this dissertation describe how various spectroscopic techniques are used: 1) to study the operation of molecular machines in solution, 2) to track the operation of molecular machines inside a single cell, and 3) to investigate the photo-decomposition pathway of a biological chromophore. Recent advances in nanotechnology have enriched the development of nano-scale molecular assemblies to be used as delivery platforms for biologically relevant molecules. Among all the molecular assemblies, molecular machines that are incorporated onto various domains of mesoporous silica nanoparticles (MSN) hold considerable potential as a reliable delivery system. Because the ease of functionalization enables chemical or photo-responsive molecular moieties to be covalently attached to the silica framework, these molecular assemblies, with defined mechanized properties, can perform specific functions under external stimuli (pH, redox, or light). While the primary function of these molecular machines is to deliver stored cargo molecules, the means of activation and the motif in which they operate are different. In the first and second chapters of this dissertation, two types of molecular machines, nanovalves and nanoimpellers, and their operations are studied. The ability to continuously monitor and image progression of molecular-based biological events in real-time can enhance our understanding of intracellular processes upon drug, protein and nucleic acid delivery. Using the photo-activated nanoimpeller described in the second chapter, the third chapter explores how it can be used to transport a nuclear staining agent, PI, inside a single cell. Nanoimpellers are made by functionalizing azobenzene molecules to the internal pore surface of MSN. The continuous cis/trans isomerizations are set in motion upon laser illumination at optimal wavelength(s), which facilitate cargo molecules to be expelled from the pores to the surrounding medium. By refining a conventional epi-fluorescence technique and complementing it with spectral acquisition, the course of the intracellular delivery event, from photo-isomeriza tion of azobenzene to PI's eventual intercalation with nuclear DNA is mapped in real-time spectroscopically. Finally, continuous spectroscopic monitoring of PI in vitro also led us to an unexpected, yet interesting observation. Upon prolonged laser exposure, both the absorption and emission maxima of PI exhibit remarkable spectral shifts. The photo-product has successfully been separated from PI using column chromatography. Spectroscopic investigations suggest that the observed large magnitude shift is the result of the N-dealkylation of the butylammonium side chain from PI. Through electron paramagnetic resonance measurement, the formation of a long-lived radical (with increasing intensity over time) is detected during this photo-decomposition process.

Lau, Yuen Agnes

383

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

SciTech Connect

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.

Vargas Alvarez, Carlos A.; Kobulnicky, Henry A. [Department of Physics and Astronomy, University of Wyoming, Dept. 3905, Laramie, WY 82071 (United States); Bradley, David R.; Kannappan, Sheila J.; Norris, Mark A. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, CB 3255, Phillips Hall, Chapel Hill, NC 27599-3255 (United States); Cool, Richard J. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Miller, Brendan P., E-mail: cvargasa@uwyo.edu, E-mail: chipk@uwyo.edu, E-mail: davidbradley512@gmail.com, E-mail: sheila@physics.unc.edu, E-mail: manorris@physics.unc.edu, E-mail: rcool@obs.carnegiescience.edu, E-mail: mbrendan@umich.edu [Department of Astronomy, University of Michigan, 745 Dennison Building, 500 Church St., Ann Arbor, MI 48109 (United States)

2013-05-15

384

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

NASA Astrophysics Data System (ADS)

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).

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

385

NMR spectroscopic analysis reveals extensive binding interactions of complex xyloglucan oligosaccharides with the Cellvibrio japonicus glycoside hydrolase family 31 ?-xylosidase.  

PubMed

The study of the interaction of glycoside hydrolases with their substrates is fundamental to diverse applications in medicine, food and feed production, and biomass-resource utilization. Recent molecular modeling of the ?-xylosidase CjXyl31A from the soil saprophyte Cellvibrio japonicus, together with protein crystallography and enzyme-kinetic analysis, has suggested that an appended PA14 protein domain, unique among glycoside hydrolase family 31 members, may confer specificity for large oligosaccharide fragments of the ubiquitous plant polysaccharide xyloglucan (J. Larsbrink, A. Izumi, F.M. Ibatullin, A. Nakhai, H.J. Gilbert, G.J. Davies, H. Brumer, Biochem. J. 2011, 436, 567-580). In the present study, a combination of NMR spectroscopic techniques, including saturation transfer difference (STD) and transfer NOE (TR-NOE) spectroscopy, was used to reveal extensive interactions between CjXyl31A active-site variants and xyloglucan hexa- and heptasaccharides. The data specifically indicate that the enzyme recognizes the entire cello-tetraosyl backbone of the substrate and product in positive enzyme subsites and makes further significant interactions with internal pendant ?-(1?6)-linked xylosyl units. As such, the present analysis provides an important rationalization of previous kinetic data on CjXyl31A and unique insight into the role of the PA14 domain, which was not otherwise obtainable by protein crystallography. PMID:22961810

Silipo, Alba; Larsbrink, Johan; Marchetti, Roberta; Lanzetta, Rosa; Brumer, Harry; Molinaro, Antonio

2012-10-15

386

Spectroscopic Study of Massive Young Stellar Object Candidates in the Galactic Center  

NASA Astrophysics Data System (ADS)

We present results of a spectroscopic study of massive young stellar object (YSO) candidates in the central 200 pc region of the Milky Way Galaxy, using the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. Our 107 massive YSO candidates were selected based on colors of point sources in high sensitivity Spitzer/IRAC images. Following our recent announcement of the first spectroscopic identification of massive YSOs in the Galactic Center, we show that about one third of our targets reveal spectral features characteristic of massive YSOs, such as molecular gas-phase absorptions from C2H2 (13.7 ?m), HCN (14.0 ?m), and CO2 (15.0 ?m), and solid-phase absorptions from 15 ?m CO2 ice with a broad absorption profile, suggestive of CO2 ice mixed with CH3OH ice. These IRS spectra of the YSO candidates will allow us to study the early stages of star formation in the Galactic Center.

An, Deokkeun; Ramírez, S. V.; Sellgren, K.; Arendt, R. G.; Boogert, A. C. A.; Schultheis, M.; Stolovy, S. R.; Cotera, A. S.; Robitaille, T. P.; Smith, H. A.

2010-01-01

387

Spectroscopic studies and crystal structure of (E)-N Prime -(2-hydroxy-3-methoxybenzylidene)isonicotinohydrazide  

SciTech Connect

The structure of compound has also been examined cyrstallographically. It crystallizes in the monoclinic space group P2{sub 1}/c with a = 7.673(1), b = 16.251(2), c = 10.874(1) A, {beta} = 110.42(1) Degree-Sign , V = 1270.7(3) A{sup 3}, D{sub x} = 1.418 g cm{sup -3}, R{sub 1} = 0.0349 and wR{sub 2} = 0.0935 [I > 2{sigma}(I)], respectively. The title compound has been synthesized from the reaction of isonicotinohydrazide with 2-hydroxy-3-methoxybenzaldehyde. It has been characterized by using elemental analysis, MS, IR, {sup 1}H NMR, {sup 13}C NMR and UV-Visible spectroscopic techniques.

Ozay, H., E-mail: havaozay@hotmail.com; Yildiz, M. [Canakkaale Onsekiz Mart University, Department of Chemistry, Faculty of Science and Arts (Turkey)] [Canakkaale Onsekiz Mart University, Department of Chemistry, Faculty of Science and Arts (Turkey); Unver, H. [Ankara University, Department of Physics, Faculty of Science (Turkey)] [Ankara University, Department of Physics, Faculty of Science (Turkey); Kiraz, A. [Near East University, Ataturk Faculty of Education (Turkey)] [Near East University, Ataturk Faculty of Education (Turkey)

2013-01-15

388

Spectroscopic study of emission coal mineral plasma produced by laser ablation  

NASA Astrophysics Data System (ADS)

Spectroscopic analysis of plasma produced by laser ablation of coal samples using 1064 nm radiation pulses from a Q-switched Nd:YAG on different target under air ambient, was performed. The emission of molecular band systems such as C2 Swan System (d3?g?a3?u), the First Negative System N2 (Band head at 501,53 nm) and emission lines of the C I, C II, were investigated using the optical emission spectroscopy technique. The C2 molecular spectra (Swan band) were analyzed to determine vibrational temperature (0,62 eV); the density and electron temperature of the plasma have been evaluated using Stark broadening and the intensity of the nitrogen emission lines N II, the found values of 1,2 eV and 2,2 x1018 cm?3 respectively.

Vera, L. P.; Pérez, J. A.; Riascos, H.

2014-05-01

389

Spectroscopic Analysis of Nd^3+:Y2O3 Nanocrystals in Polymers and Copolymers  

NASA Astrophysics Data System (ADS)

Spectroscopic properties of nanocrystalline Nd^3+ in Nd^3+:Y2O3 embedded in solid plastic hosts (2-hydroxyethyl methacrylate (HEMA) and copolymer of HEMA/styrene) are characterized. The standard Judd-Ofelt model has been applied to the room temperature absorption intensities of Nd^3+(4f^3) transitions in the plastic hosts to determine the three phenomenological intensity parameters: ?2, ?4, and ?6. Intensity parameters are then utilized to determine the radiative decay rates and branching ratios of the Nd^3+(4f^ 3) transitions from the upper manifold state ^4F3/2 to the lower-lying multiplet manifolds ^4IJ (J= 9/2, 11/2, 13/2, 15/2). Emission cross sections and room temperature fluorescence lifetimes of the important intermanifold ^4F3/2->^4IJ (J=9/2, 11/2, 13/2)transitions are determined. We investigate the detailed crystal-field splitting of the energy levels of the Nd^3+ ion in the Y2O3/polymer host. The 300 K spectraare analyzed for the energy level transitions between the ^2S+1LJ multiplet manifolds of Nd^3+(4f^3). Results are also compared with a crystal-field splitting analysis reported earlier for single-crystal Nd^3+:Y2O3.

Ray, Nathan; Nash, Kelly; Dennis, Robert; Gruber, John; Sardar, Dhiraj; Gen Zhang, Mao

2009-04-01

390

Spectroscopic Observations and Analysis of the Unusual Type Ia SN1999ac  

SciTech Connect

The authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from Si II are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v{sub 10}(Si II), R(Si II), v, and {Delta}m{sub 15} further underlines the unique characteristics of SN 1999ac. They find convincing evidence of C II {lambda}6580 in the day -15 spectrum with ejection velocity v > 16,000 km s{sup -1}, but this signature disappears by day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.

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

2005-07-12

391

Configuration interaction study of the electronic states and spectroscopic properties of selenium monoxide  

NASA Astrophysics Data System (ADS)

The electronic spectrum of the selenium monoxide (SeO) molecule has been studied theoretically by using ab initio based multireference singles and doubles configuration interaction (MRDCI) methodology, which includes relativistic effective core potentials (RECP) and suitable Gaussian basis sets of the atoms. Potential energy curves of several electronic states correlating with the lowest and second dissociation limit are constructed. Spectroscopic parameters, namely Te, re, and ?e of 10 bound ?-S states of the molecule within 4.71 eV are estimated and compared with the available data. In addition, binding energies of the ground and some excited states are computed. The changes in the potential energy curves and spectroscopic properties after the inclusion of the spin-orbit coupling are discussed and also compared with the available data. Transition probabilities of some dipole-allowed and spin forbidden transitions are estimated and radiative lifetimes of some excited states are reported. Dipole moments of some low-lying ?-S states as a function of bond distance have also been computed.

Chattopadhyaya, Surya; Nath, Abhijit; Das, Kalyan Kumar

2012-04-01

392

A single-photon fluorescence and multi-photon spectroscopic study of atherosclerotic lesions  

NASA Astrophysics Data System (ADS)

In this study we compare the single-photon autofluorescence and multi-photon emission spectra obtained from the luminal surface of healthy segments of artery with segments where there are early atherosclerotic lesions. Arterial tissue was harvested from atherosclerosis-prone WHHL-MI rabbits (Watanabe heritable hyperlipidemic rabbit-myocardial infarction), an animal model which mimics spontaneous myocardial infarction in humans. Single photon fluorescence emission spectra of samples were acquired using a simple spectrofluorometer set-up with 400 nm excitation. Samples were also investigated using a home built multi-photon microscope based on a Ti:sapphire femto-second oscillator. The excitation wavelength was set at 800 nm with a ~100 femto-second pulse width. Epi-multi-photon spectroscopic signals were collected through a fibre-optics coupled spectrometer. While the single-photon fluorescence spectra of atherosclerotic lesions show minimal spectroscopic difference from those of healthy arterial tissue, the multi-photon spectra collected from atherosclerotic lesions show marked changes in the relative intensity of two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) signals when compared with those from healthy arterial tissue. The observed sharp increase of the relative SHG signal intensity in a plaque is in agreement with the known pathology of early lesions which have increased collagen content.

Smith, Michael S. D.; Ko, Alex C. T.; Ridsdale, Andrew; Schattka, Bernie; Pegoraro, Adrian; Hewko, Mark D.; Shiomi, Masashi; Stolow, Albert; Sowa, Michael G.

2009-06-01

393

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

PubMed

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. PMID:24680836

Georgieva, I; Mihaylov, Tz; Trendafilova, N

2014-06-01

394

Two-dimensional infrared study of 3-azidopyridine as a potential spectroscopic reporter of protonation state  

SciTech Connect

The lack of general spectroscopic probes that can be used in a range of systems to probe kinetics and dynamics is a major obstacle to the widespread application of two-dimensional infrared (2D IR) spectroscopy. We have studied 3-azidopyridine to characterize its potential as a probe of the protonation state of the pyridine ring. We find that the azido-stretching vibration is split by accidental Fermi resonance interactions with one or more overtones and combination states. Using 2D IR spectroscopy, we determine the state structure of the resulting eigenstates for complexes of 3-azidopyridine with formic acid and trifluoroacetic acid in which the pyridine ring is unprotonated and protonated, respectively. Based on the measurements, we develop a two-oscillator depurturbation model to determine the energies and couplings of the zeroth-order azido-stretching state and the perturbing dark state that couples to it. Based on these results, we conclude that the azido-stretching vibration is, in fact, sensitive to the protonation state of the pyridine shifting up in frequency by 8 cm{sup -1} in the complex with trifluoroacetic acid relative to the formic acid complex. These results suggest that, although 3-azidopyridine is not suitable as a spectroscopic probe, the approach of employing an organic azide as a remote probe of protonation state holds significant promise.

Nydegger, Michael W.; Dutta, Samrat; Cheatum, Christopher M. [Department of Chemistry, University of Iowa, Iowa City, Iowa 52242 (United States)

2010-10-07

395

A study of the ISM with large massive-star optical spectroscopic surveys  

NASA Astrophysics Data System (ADS)

We are conducting a study on the imprint of the ISM on optical spectra based on two types of ongoing spectroscopic massive-star surveys: on the one hand, intermediate-resolution (R = 2500) green-blue spectra for ˜3000 stars obtained with the Galactic O Star Spectroscopic Survey (GOSSS). On the other hand, high-resolution (R = 23 000 - 65 000) optical spectra for 600 stars obtained from three different surveys, OWN, IACOB, and NoMaDS. The R = 2500 data allows us to reach a larger sample with an average larger extinction while the R = 23 000 - 65 000 sample provides access to more diffuse interstellar bands (DIBs) and allows for the resolution in velocity of some ISM features. For each spectrum we are measuring the equivalent widths, FWHMs, and central wavelengths of 10-40 DIBs and interstellar lines (e.g. Ca II H+K, Na I D1+D2) and, in the case of GOSSS, the existence of an H II region around the star. We have also derived from auxiliary data or compiled from the literature values for the reddening, extinction law, H I column density, parallax, and H? emission. All of this constitutes the most complete collection ever of optical information on the ISM within 3 kpc of the Sun. We are analyzing the correlations between all of the collected quantities to discriminate between different possible origins of the DIBs.

Penadés Ordaz, M.; Maíz Apellániz, J.; Sota, A.

2013-05-01

396

Quantitative infrared spectroscopic method for the study of the hydration of ions in aqueous solutions  

SciTech Connect

An infrared spectroscopic method for the study of the hydration of ions in aqueous solutions has been developed. OD stretching bands of isotopically dilute HDO molecules in the first hydration sphere of ions are obtained when the absorption from H/sub 2/O molecules and HDO molecules in the bulk water are removed by a double difference technique. The method is applied to aqueous solutions of Ni(ClO/sub 4/)/sub 2/, Ni(BF/sub 4/)/sub 2/, and Ni(PF/sub 6/)/sub 2/. Coordination numbers of 4.6 +/- 0.8 for the ClO/sub 4//sup -/ anion and 3.9 +/- 0.8 for the BF/sub 4//sup -/ anion are obtained. A systematic study of the influence of different salt and HDO concentrations has been undertaken. It is found that Lambert-Beer's law is valid in the concentration ranges studied.

Kristiansson, O.; Lindgren, J.; de Villepin, J.

1988-05-05

397

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

NASA Astrophysics Data System (ADS)

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.

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

1998-03-01

398

Spectroscopic, crystallographic and theoretical studies of lasalocid complex with ammonia and benzylamine  

NASA Astrophysics Data System (ADS)

A natural antibiotic - Lasalocid is able to form stable complexes with ammonia and organic amines. New complexes of lasalocid with benzylamine and ammonia were obtained in the crystal forms and studied using X-ray, FT-IR, 1H NMR, 13C NMR and DFT methods. These studies have shown that in both complexes the proton is transferred from the carboxylic group to the amine group with the formation of a pseudo-cyclic structure of lasalocid anion complexing the protonated amine or NH4+ cation. The spectroscopic and DFT studies demonstrated that the structure of the complex formed between Lasalocid and benzylamine in the solid is also conserved in the solution and gas phase. In contrast, the structure of the complex formed between lasalocid and ammonium cation found in the solid state undergoes dissociation in chloroform solution accompanied with a change in the coordination form of the NH4+ cation.

Huczy?ski, Adam; Janczak, Jan; Rutkowski, Jacek; Brzezinski, Bogumil

399

Studies on molecular weaker interactions, spectroscopic analysis and chemical reactivity of synthesized ethyl 3,5-dimethyl-4-[3-(2-nitro-phenyl)-acryloyl]-1H-pyrrole-2-carboxylate through experimental and quantum chemical approaches  

NASA Astrophysics Data System (ADS)

Ethyl 3,5-dimethyl-4-[3-(2-nitro-phenyl)-acryloyl]-1H-pyrrole-2-carboxylate (EDNPAPC) has been synthesized and characterized by 1H NMR, UV-Vis, FT-IR and Mass spectroscopy. Geometrical, spectral, thermodynamic properties have been calculated and evaluated using DFT level of theory, B3LYP functional and 6-31G(d,p) basis set. The observed absorption peaks at 364, 308 and 256 nm are corresponds to the calculated electronic transitions at 352, 286 nm and 252 nm respectively. The experimental data shows red shift in comparison to the calculated. The detailed vibrational analysis has been carried out with the aid of potential energy distribution (PED) and the experimental FTIR peaks confirm red shifts in Nsbnd H and Cdbnd O stretching bond as result of dimer formation. The multiple interactions present in the molecule have been evaluated with the help of QTAIM theory. The ellipticity values confirm the presence of resonance assisted hydrogen bonding in dimer formation. The binding energy of dimer formation through DFT and AIM calculations has been found to be 13.94 and 15.22 kcal/mol respectively. The binding energy of dimer after basis set superposition error (BSSE) found to be as 10.54 kcal/mol. Theoretical result from reactivity descriptors show that C6, C13 and C15 are more reactive sites for nucleophilic attack within molecule favoring the formation of heterocyclic compounds such as pyrazoline and oxazoline. The calculated ?0 values for monomer and dimer are found to be as 1.8 × 10-30, 7.8 × 10-30 esu, respectively, indicating that this pyrrole chalcone is an attractive material for nonlinear optical (NLO) applications.

Singh, R. N.; Baboo, Vikas; Rawat, Poonam; Gupta, V. P.

2013-04-01

400

Behind the Reactivity of Lactones: A Computational and Spectroscopic Study of Phenol·?-Butyrolactone.  

PubMed

In this work, the intermolecular interaction between phenol and ?-butyrolactone (GBL) has been studied by a combination of spectroscopic and computational techniques. The electronic and vibrational transitions of phenol·GBL were measured in a supersonic jet expansion by resonant two-photon ionization (R2PI) and ion dip IR (IDIR) spectroscopy. The results obtained were compared with calculations carried out with both M06-2X and MP2 molecular orbital methods in order to characterize the intermolecular interactions. The singly detected conformer is stabilized by a relatively strong hydrogen bond in which phenol acts as a proton donor to the carbonyl group of GBL. The phenol·GBL2 cluster has also been studied, finding up to three populated conformers. Nevertheless, in the three species, the main interaction between the phenolic hydroxyl group and the GBL's carbonyl group remains similar to that of phenol·GBL. Furthermore, the C?O···H interaction is reinforced. PMID:24678986

León, Iker; González, Jorge; Millán, Judith; Castaño, Fernando; Fernández, José A

2014-04-10

401

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

402

Infrared Spectroscopic Studies with the Stratospheric Observatory for Infrared Astronomy (sofia)  

NASA Astrophysics Data System (ADS)

The joint U.S. and German Stratospheric Observatory for Infrared Astronomy (SOFIA) will be a premier facility for studying the physics and chemistry of the interstellar medium and the stellar evolution process for many decades. SOFIA's first-generation instrument complement includes broadband imagers, moderate resolution spectrographs capable of resolving broad features due to dust and large molecules, and high resolution spectrometers suitable for kinematic studies of molecular and atomic gas lines at km/s resolution. SOFIA spectroscopic science applications will be discussed, with special emphasis on investigations related to infrared spectroscopy of astrophysical gas, grains, and ices. First light images and early science results related to these topics will be presented.

Gehrz, R. D.; Becklin, E. E.

2011-06-01

403

Spectroscopic studies of copper ions doped in tellurate glasses obtained by sol - gel method  

NASA Astrophysics Data System (ADS)

The preparation of copper nitrate doped tellurate glasses by sol- gel method and spectroscopic studies of this tellurate system are reported. FTIR spectroscopy results show that this glass consists of [TeO6], [TeO4] and [TeO3] structural units and indicate that six- coordinated tellurium (VI) in [TeO6] units were partially changed to fourcoordinated tellurium (IV) in [TeO4] units during the doping with Cu(NO3)2. EPR spectra of the studied glasses were obtained due to the presence of Cu2+ paramagnetic ions and reveal the local order in matrix, the distribution and valence state of cooper ions. Thus, the EPR spectra show a partially resolved parallel hyperfine structure and no resolved perpendicular structure. The EPR spectra could be a superposition of two signals, one due to isolated Cu2+ ions in axial neighborhood, and the other due to the presence of magnetically coupled Cu2+ species.

Dehelean, A.; Rada, S.; Danciu, V.; Culea, E.; Stan, M.; Popa, A.; Raita, O.

2012-02-01

404

Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis, and fundamental stellar parameters  

NASA Astrophysics Data System (ADS)

Context. Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. In addition, the evolutionary tracks of the earlier Herbig Ae stars cross the theoretical PMS instability strip located roughly in the same area of the HR diagram as the ? Scuti variables. Many of these stars exhibit pulsations of ? Scuti type. Aims: Understanding the internal structure of pulsating Herbig Ae stars based on asteroseismic studies will help constraining the origin of their tremendous activity, winds, and variability. It is therefore necessary to investigate the location of the PMS instability strip and of its boundaries, and to extend the sample of observed and studied pulsating Herbig Ae stars. The aim of this work was to carry out a thorough analysis of the line profile variations of the prototype Herbig Ae star HD 104237 based on high-resolution spectroscopy and to redetermine precisely its fundamental parameters, which are the basic ingredients of a forthcoming asteroseismic modeling. Methods: HD 104237 is a pulsating Herbig Ae star with eight detected frequencies based on the analysis of radial velocity variations. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile by working on dynamical spectra of equivalent photospheric (LSD) profiles of HD 104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present the results of these analysis including the mode identification corresponding to the detected dominant frequency, as well as a new determination of its fundamental stellar parameters. Results: The analysis of spectroscopic data set of April 22-25 obtained at SAAO in 1999 has confirmed the presence of multiple oscillation modes of low-degree ? in HD 104237 and led to the first direct detection of a non-radial pulsation mode in this star: the dominant mode F1 was identified by the Fourier 2D method having a degree ? value comprised between 1 and 2, the symmetry of the pattern variation indicating an azimuthal order of ± 1. The detailed study of the fundamental stellar parameters has provided a Teff, log g, and iron abundance of 8550 ± 150 K, 3.9 ± 0.3, and -4.38 ± 0.19 (i.e. [Fe/H] = +0.16 ± 0.19 ), respectively. Based on observations collected at the 1.9 m SAAO telescope.

Fumel, A.; Böhm, T.

2012-04-01

405

Study on molecular structure, spectroscopic investigation (IR, Raman and NMR), vibrational assignments and HOMO-LUMO analysis of L-sodium folinate using DFT: a combined experimental and quantum chemical approach.  

PubMed

In the present work, an exhaustive conformational search of N-[4-[[(2-amino-5-formyl-(6S)-3,4,5,6,7,8-hexahydro-4-oxo-6-pteridinyl)methyl]amino]benzoyl]-L-glutamic acid disodium salt (L-SF) has been preformed. The optimized structure of the molecule, vibrational frequencies and NMR spectra studies have been calculated by density functional theory (DFT) using B3LYP method with the 6-311++G (d, p) basis set. IR and FT-Raman spectra for L-SF have been recorded in the region of 400-4000 cm(-1) and 100-3500 cm(-1), respectively. 13C and 1H NMR spectra were recorded and 13C and 1H nuclear magnetic resonance chemical shifts of the molecule were calculated based on the gauge-independent atomic orbital (GIAO) method. Finally all of the calculation results were applied to simulate IR, Raman, 1H NMR and 13C NMR spectrum of the title compound which showed excellent agreement with observed spectrum. Furthermore, reliable vibrational assignments which have been made on the basis of potential energy distribution (PED) and characteristic vibratinonal absorption bands of the title compound in IR and Raman have been figured out. HOMO-LUMO energy and Mulliken atomic charges have been evaluated, either. PMID:24177877

Li, Linwei; Cai, Tiancheng; Wang, Zhiqiang; Zhou, Zhixu; Geng, Yiding; Sun, Tiemin

2014-02-24

406

Stokes shift spectroscopic analysis of multifluorophores for human cancer detection in breast and prostate tissues  

NASA Astrophysics Data System (ADS)

Stokes shift spectroscopy (S3) offers a novel and simpler way to rapidly recognize spectral fingerprints of multiple fluorophores in complex media such as in tissue. This spectroscopic technique can be used as an effective approach to detect cancer in tissue. The alterations of the measured S3 spectra between cancerous and normal tissues were observed in human breast and prostate samples. In order to obtain the optimal Stokes shift interval, ??i, for the purpose of breast/prostate cancer detection using S3, the S3 spectra of a mixed aqueous solution of tryptophan, nicotinamide adenine dinucleotide, and flavin were measured with different ??i values. The experimental results analyzed using nonnegative least square method show that there is a reduced contribution from collagen and an increased contribution from tryptophan to the S3 signal of the cancerous tissue as compared with those of the normal tissue. This study indicates that the changes of relative contents of tryptophan and collagen in tissue shown by the S3 spectra may present potential native biomarkers for breast and prostate cancer detection. S3 has the potential to be a new armamentarium.

Pu, Yang; Wang, Wubao; Yang, Yuanlong; Alfano, Robert R.

2013-01-01

407

Spectroscopic and thermodynamic studies on the binding of gadolinium(III) to human serum transferrin  

SciTech Connect

A wide variety of thermodynamic, kinetic, and spectroscopic studies have demonstrated differences between the two metal-binding sites of transferrin. In the present investigation, the authors have further assessed these differences with respect to the binding of gadolinium, evaluated by UV difference spectrophotometry, electron paramagnetic resonance (EPR) titration, EPR difference spectroscopy in conjunction with urea gel electrophoresis, and equilibrium dialysis. Combinations of these studies establish that only one site of the protein binds Gd(III) sufficiently firmly to be characterized. In order to reveal which of the two sites accepts Gd(III), we made use of monoferric transferrins preferentially loaded with Fe(III) at either site in EPR spectroscopic studies. Because of the overlap of signals, difference spectroscopy was required to distinguish resonances arising from Fe(III) and Gd(III) specifically complexed to the protein. When iron is bound to the C-terminal site, leaving the N-terminal site free for binding of gadolinium, the difference spectrum shows no evidence of specific binding. However, when iron is bound to the N-terminal site, the difference spectrum shows a resonance line at g' = 4.1 indicative of specific binding, thus implicating the C-terminal site in the binding of Gd(III). The effective stability constant for the binding of Gd(III) to this site of transferrin at pH 7.4 and ambient pCO/sub 2/ is 6.8 x 10/sup 6/ M/sup -1/. At physiological pCO/sub 2/, the formation of nonbinding carbonato complexes of Gd(III) precludes a substantial role from transferrin in the transport of the lanthanide in vivo.

Zak, O.; Aisen, P.

1988-02-09

408

Mössbauer spectroscopic study of iron phosphate catalysts used in selective oxidation  

NASA Astrophysics Data System (ADS)

Three iron phosphate compounds FePO4, Fe2P2O7 and Fe7(PO4)6 have been synthesized and studied as catalysts for the oxidative dehydrogenation of isobutyric acid to methacrylic acid. Mössbauer spectroscopic characterization of the solids before and after catalytic reaction has allowed us to show that the starting phases were transformed in the conditions of reaction and that a new phase was formed. This new phase is a mixed Fe3+ and Fe2+ phosphate with a Fe3+/Fe2+ ratio of 1.8±0.2 with Mössbauer parameters: ?1=0.47 ± 0.05, ?1=0.68± 0.02 mm.s-1 and ?2=1.20 ± 0.05, ?2=2.73±0.02 mm.s-1. This new phase appears to be elective for methacrylic acid formation.

Millet, J. M.; Virely, C.; Forissier, M.; Bussière, P.; Vedrine, J. C.