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1

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

2

Conformational analysis and vibrational spectroscopic studies on dapsone  

NASA Astrophysics Data System (ADS)

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

Ildiz, Gulce Ogruc; Akyuz, Sevim

2012-11-01

3

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

4

Miscibility studies of indomethacin and Eudragit® E PO by thermal, rheological, and spectroscopic analysis.  

PubMed

The objective of this study is to understand the underlying mechanisms responsible for the superior stability of indomethacin (INM)-Eudragit® E PO (E PO) system by exploring the miscibility and intermolecular interactions through the combination of thermal, rheological, and spectroscopic analysis. The zero shear-rate viscosity drops monotonically with the increase of INM concentration at 145 °C, suggesting that E PO and INM form a solution and the small molecular drug acts as a plasticizer. Flow activation energy was calculated from the viscosity data at different temperature. The glass transition temperature (T(g)) of the mixture at different composition was determined using differential scanning calorimetry. The T(g) and flow activation energy peak at the INM concentration around 60%-70%. Fourier transform infrared analysis provided direct evidence for the intermolecular ionic interactions, which may disrupt the dimer formation of amorphous INM. The study explained the superior stability of INM-E PO mixtures, and demonstrated that a combination of thermal, rheological, and spectroscopic technologies can help us to obtain a full picture of the drug-polymer interactions and to determine the formulation and processing conditions. PMID:22396240

Liu, Huiju; Zhang, Xueyan; Suwardie, Herman; Wang, Peng; Gogos, Costas G

2012-06-01

5

The study of interaction between PFOA/PFOS and uracil by topology quality and spectroscopic analysis  

NASA Astrophysics Data System (ADS)

It has been established that perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) can be considered as emerging persistent organic pollutants. In recent years, there was increasing distribution of PFOA/PFOS in environmental systems, and accumulation and toxic effects of PFOA/PFOS in human body. In this paper, quantum chemistry methods were employed to study the interaction between perfluorinated organic pollutants and base (uracil). The results showed that there were four stable binding modes between the two perfluorinated compounds with uracil, especially the second mode which caused the most detrimental physiological functional response. NBO analysis showed that reactive hydrogen in the two perfluorinated compounds had the greatest effect on the hydrogen bond. The nature of the hydrogen bond formed between the two perfluorinated compounds and base was investigated using the AIM theory. The changes of spectroscopic properties in complexes were analyzed by IR and NMR spectra.

Xu, Hui-Ying; Zhu, Jian-Qing; Wang, Wei; Xu, Xiao-Lu; Lu, Yin

2014-02-01

6

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.

7

Spectroscopic studies of glass structure  

SciTech Connect

Today`s understanding of the molecular-level structure of inorganic glasses has been transformed by the availability of a wide range of sensitive spectroscopic probes. Today we can relate glass composition to quantitative distributions of glass-forming cations and to changes in oxygen bonding and modifying cation geometries. Future spectroscopic studies will result in improved descriptions of anion and cation geometries and should provide glass scientists with the capability to optimize atomic arrangements for specific optical, electrical, and thermal properties.

Brow, R.K.

1994-08-01

8

Nuclear spectroscopic studies  

SciTech Connect

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

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

1993-02-08

9

Integrated Spectroscopic Studies of MIL03346  

NASA Technical Reports Server (NTRS)

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 here results of an integrated series of measurements made on the same split of MIL03346, in order to expand our understanding of the properties of these materials and to relate them to other SNCs.

Dyar, M. D.; Pieters, C. M.; Hiroi, T.; Lane, M. D.; Marchand, G. J.

2005-01-01

10

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

11

Vibrational spectroscopic studies of N,N'-dimethylpropyleneurea-water system: affected solvent spectra and factor analysis.  

PubMed

FT-IR spectra of N,N'-dimethylpropyleneurea (DMPU)-water system have been measured in the 4000-500 cm(-1) range by Attenuated Total Reflectance (ATR) technique in the entire composition range. The hydration of DMPU in diluted aqueous solutions has been additionally studied with transmission FT-IR spectroscopy of isotopically diluted HDO in H(2)O, used as a probe of solute hydration. The spectra have been analysed with the quantitative version of the difference spectra method that leads to isolation of the spectrum of solvent affected by the presence of the solute. DMPU-affected HDO spectra provide information about the energetic state of water molecules in the hydration shell, while affected H(2)O spectra additionally reflect the structural state of the water hydrogen bond network. The CO stretching band of DMPU has been used to obtain also the H(2)O-affected DMPU spectrum. The affected H(2)O and DMPU spectra have been determined in infinite dilution approximation, as well as for increasing concentrations of the solute. These results are confronted with factor analysis of ATR spectra, which shows the presence of three well-defined intermolecular complexes in the studied system. Presumable structures of these complexes have been proposed on the basis of Density Functional Theory (DFT) calculations of optimal cluster geometries. PMID:20869300

?miechowski, Maciej

2011-08-15

12

ESCA studies of the surface chemistry of lunar fines. [Electron Spectroscopic Chemical Analysis  

NASA Technical Reports Server (NTRS)

The paper presents an ESCA analysis based on the use of a synthetic lunar-glass standard that allows determination of the surface composition of lunar samples with an accuracy that appears to be better than 10% of the amount present for all major elements except Ti. It is found that, on the average, grain surfaces in the lunar fines samples 10084 and 15301 are strongly enriched in Si, moderately enriched in Fe, moderately depleted in Al and Ca, and strongly depleted in Mg. This pattern could not be produced by the deposition of any expected meteoritic vapor. Neither could it be produced by simple inverse-mass-dependent element loss during sputtering. It is suggested that at least part of the pattern may be a simple consequence of agglutinate glass formation in the fines since there is some evidence that Si can become enriched on the surface of silicate melts. These results do not support the strong enrichments in Fe on grain surfaces reported from Auger studies.

Housley, R. M.; Grant, R. W.

1976-01-01

13

Experimental and theoretical spectroscopic analysis, HOMO-LUMO, and NBO studies of cyanuric chloride.  

PubMed

The vibrational spectral analysis of cyanuric chloride was carried out by using FT-Raman and FT-IR spectra in the range 100-4000cm(-1) and 400-4000cm(-1) respectively. The structure optimization was done and structural characteristics were determined by Density Functional Theory (B3LYP) method with 6-31G(d,p) and 6-311++G(d,p) basis sets. The vibrational wavenumbers have been calculated and scaled values are compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED). The Natural bonding orbital (NBO) analysis performed to confirm the stability of the molecule arising from hyper conjugation and delocalization. The Mulliken atomic charges were also calculated. The computed HOMO-LUMO energy gap shows that charge transfer occurs within the molecule. The thermodynamic properties at different temperatures have been calculated from the vibrational analysis. PMID:24650880

Prabhaharan, M; Prabakaran, A R; Srinivasan, S; Gunasekaran, S

2014-06-01

14

Experimental and theoretical spectroscopic analysis, HOMO-LUMO, and NBO studies of cyanuric chloride  

NASA Astrophysics Data System (ADS)

The vibrational spectral analysis of cyanuric chloride was carried out by using FT-Raman and FT-IR spectra in the range 100-4000 cm-1 and 400-4000 cm-1 respectively. The structure optimization was done and structural characteristics were determined by Density Functional Theory (B3LYP) method with 6-31G(d,p) and 6-311++G(d,p) basis sets. The vibrational wavenumbers have been calculated and scaled values are compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED). The Natural bonding orbital (NBO) analysis performed to confirm the stability of the molecule arising from hyper conjugation and delocalization. The Mulliken atomic charges were also calculated. The computed HOMO-LUMO energy gap shows that charge transfer occurs within the molecule. The thermodynamic properties at different temperatures have been calculated from the vibrational analysis.

Prabhaharan, M.; Prabakaran, A. R.; Srinivasan, S.; Gunasekaran, S.

2014-06-01

15

Spectroscopic, electronic structure and natural bond orbital analysis of o-fluoronitrobenzene and p-fluoronitrobenzene: A comparative study  

Microsoft Academic Search

Experimental FTIR, FT-Raman and FT-NMR spectroscopic studies of o-fluoronitrobenzene and p-fluoronitrobenzene have been carried out. A detailed quantum chemical calculations have been performed using DFT\\/B3LYP method with 6-311++G** and 6-31G** basis sets. Complete vibrational analyses of the compounds were performed. The temperature dependence of thermodynamic properties has been analysed. The atomic charges, electronic exchange interaction and charge delocalisation of the

V. Arjunan; S. Thillai Govindaraja; S. Sakiladevi; M. Kalaivani; S. Mohan

2011-01-01

16

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

17

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

18

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

19

The Spectroscopic study of {sup 33}Ar  

SciTech Connect

The proton-rich nucleus {sup 33}Ar has been produced at the low-energy facility SPIRAL at GANIL. Spectroscopic studies of gamma and p emission of this nucleus were performed with the 'Silicon Cube' detection system. The analysis of proton and gamma singles and coincidence spectra allowed us to establish a complete decay scheme of this nucleus. The comparison of the Gamow-Teller strength distribution deduced from our experiment and the theoretical one obtained with the Shell Model permitted the determination of a quenching factor for the Gamow-Teller strength.

Adimi, N. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, Universite Bordeaux 1, UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan (France); Faculte de Physique, USTHB, B.P.32, El Alia, 16111 Bab Ezzouar, Alger (Algeria); Dominguez-Reyes, R.; Alcorta, M.; Borge, M. J. G.; Perea, A.; Tengblad, O. [Institutode Estructura de la Materia, CSIC, Serrano 113bis, E-28006-Madrid (Spain); Bey, A.; Blank, B.; Dossat, C.; Giovinazzo, J.; Matea, I. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, Universite Bordeaux 1, UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP 120, F-33175 Gradignan (France); Oliveira Santos, F. de; Madurga, M.; Thomas, J. C. [Grand Accelerateur National d'Ions Lourds, B.P. 55027, F-14076 Caen Cedex 05 (France); Fynbo, H. O. U.; Knudsen, H. H. [Department of Physics and Astronomy, University of Aarhus, Ny Munkegade 1520, DK-8000 Aarhus C (Denmark); Suemmerer, K. [Gesellschaft fuer Schwerionenforschung mbH, Planckstrasse 1, D-64291 Darmstadt (Germany)

2011-10-28

20

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

21

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

22

Interaction of salmon gonadotropin subunits : spectroscopic studies  

E-print Network

Interaction of salmon gonadotropin subunits : spectroscopic studies R. SALESSE, J. GARNIER, B en Josas, France Summary. Pituitary gonadotropins of female and male pacific salmon Oncorhynchus) and in salmon (Donaldson et al., 1972), although physicochemical, biological or immunological evidence for two

Paris-Sud XI, Université de

23

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

24

Qualitative spectroscopic study of magnetic nozzle flow  

NASA Technical Reports Server (NTRS)

The physics of the magnetic nozzle flow for a 100-kW-level quasi-steady MPD thruster was studied by photographic spectroscopy focusing on the plasma model in the flow and the acceleration mechanism. Spectroscopic visualization for the flow-species analysis indicates that the plasma-exhaust flow dominated by NII species were confined by the magnetic nozzle effect to collimate the flow for the better thruster performance. Inside the nozzle, the plasma flow was found to be in nonhomogeneous collisional-radiative condition. There appears to be a substantial flow acceleration from the magnetic nozzle inlet to the outlet with slight expansion. This suggests that the flow resembles that of constant area supersonic duct flow with cooling.

Umeki, T.; Turchi, P. J.

1992-01-01

25

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

26

Spectroscopic study in Z-pinch discharge  

SciTech Connect

The temporal variation of the emitted line intensity has been investigated, and thus an important information about the dynamic ionization stages in the Z-pinch discharge has been studied. Also the electron temperature Te, has been deduced by using a spectroscopic technique.

Garamoon, A.A.; Saudy, A.H.; Shark, W. [Al-Azhar Univ., Cairo (Egypt)] [and others

1995-12-31

27

Study of bacteria by spectroscopic techniques  

Microsoft Academic Search

Raman and Laser Induced Fluorescence (LIF) spectroscopic techniques were used for studying Azotobacter vinelandii- a genus of free-living diazotrophic soil bacteria. Azotobacter has generated a great deal of interest owing to their unique mode of metabolism. It is a large, obligately aerobic soil bacterium, which has one of the highest respiratory rates known among living organisms and is able to

Vidhu S. Tiwari; Chan Kyu Kim; Fang-Yu Yueh; Jagdish P. Singh; Michael Cunningham Jr.; Lakshmi Pulakat; Nara Gavini; Paresh Chandra Ray

2006-01-01

28

Binding of the iminium and alkanolamine forms of sanguinarine to lysozyme: spectroscopic analysis, thermodynamics, and molecular modeling studies.  

PubMed

Sanguinarine (SGR) exists in charged iminium (SGRI) and neutral alkanolamine (SGRA) forms. The binding of these two forms to the protein lysozyme (Lyz) was investigated by fluorescence, UV-vis absorbance and circular dichroism spectroscopy, and in silico molecular docking approaches. Binding thermodynamics were studied by microcalorimetry. Both forms of sanguinarine quenched the intrinsic fluorescence of Lyz, but the quenching efficiencies varied on the basis of binding that was derived after correction for an inner-filter effect. The equilibrium binding constants at 25 ± 1.0 °C for the iminium and alkanolamine forms were 1.17 × 10(5) and 3.32 × 10(5) M(-1), respectively, with approximately one binding site for both forms of the protein. Conformational changes of the protein in the presence of SGR were confirmed by absorbance, circular dichroism, three-dimensional fluorescence, and synchronous fluorescence spectroscopy. Microcalorimetry data revealed that SGRI binding is endothermic and predominantly involves electrostatic and hydrophobic interactions, whereas SGRA binding is exothermic and dominated by hydrogen-bonding interactions. The molecular distances (r) of 3.27 and 3.04 nm between the donor (Lyz) and the SGRI and SGRA acceptors, respectively, were calculated according to Förster's theory. These data suggested that both forms were bound near the Trp-62/63 residues of Lyz. Stronger binding of SGRA than SGRI was apparent from the results of both structural and thermodynamic experiments. Molecular docking studies revealed that the putative binding site for the SGR analogues resides at the catalytic site. The docking results are in accordance with the spectroscopic and thermodynamic data, further validating the stronger binding of SGRA over SGRI to Lyz. The binding site is situated near a deep crevice on the protein surface and is close to several crucial amino acid residues, including Asp-52, Glu-35, Trp-62, and Trp-63. This study advances our knowledge of the structural nature and thermodynamic aspects of binding between the putative anticancer alkaloid sanguinarine and lysozyme. PMID:25354369

Jash, Chandrima; Payghan, Pavan V; Ghoshal, Nanda; Suresh Kumar, Gopinatha

2014-11-20

29

Synthesis, spectroscopic studies and thermal analysis of charge-transfer complex of 2,2?-bipyridine with 4-hydroxybenzoic acid in different polar solvents  

NASA Astrophysics Data System (ADS)

The charge-transfer (CT) complex formed between 2,2?-bipyridine with 4-hydroxybenzoic acid has been studied in methanol and acetone at room temperature. The charge-transfer complex was characterized on the basis of FT-IR, 1H NMR, XRD studies of the solid CT complex, UV-Visible spectroscopy, thermogravimetric analysis (TGA-DTA) and conductivity and the results were discussed. The particle size and the energy of the charge-transfer complex were also determined. The data obtained from the spectroscopic studies indicate the formation of 1:1 charge-transfer complex, associated with a proton migration from the acceptor to the donor followed by intermolecular hydrogen bonding. The conductivity was found to increase with increase in the concentration of the donor.

Rzokee, Abdulsatar Abduljabbar; Ahmad, Afaq

2014-11-01

30

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.

31

Nuclear spectroscopic studies. Progress report  

SciTech Connect

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

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

1994-02-18

32

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

33

Nuclear spectroscopic studies. Progress report  

SciTech Connect

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

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

1993-02-08

34

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

35

A spectroscopic analysis of the chemically peculiar star HD 207561  

NASA Astrophysics Data System (ADS)

In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD 207561. During a survey programme to search for new rapidly oscillating Ap (roAp) stars in the Northern hemisphere, Joshi et al. observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz (P ˜ 6 min). However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD 207561, high-resolution spectroscopic and spectropolarimetric observations were carried out. A reasonable fit of the calculated H? line profile to the observed one yields an effective temperature (Teff) and surface gravity (log g) of 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (v sin i) for HD 207561 is 74 km s-1, indicative of a relatively fast rotator. The position of HD 207561 in the Hertzsprung-Russell diagram implies that this is slightly evolved from the main-sequence and located well within the ?-Scuti instability strip. The abundance analysis indicates the star has slight underabundances of Ca and Sc and mild overabundances of iron-peak elements. The spectropolarimetric study of HD 207561 shows that the effective magnetic field is within the observational error of 100 G. The spectroscopic analysis revealed that the star has most of the characteristics similar to an Am star, rather than an Ap star, and that it lies in the ?-Scuti instability strip; hence roAp pulsations are not expected in HD 207561, but low-overtone modes might be excited. The present work is based on the analysis of data collected with the Russian 6-m telescope BTA operated by the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS).

Joshi, S.; Semenko, E.; Martinez, P.; Sachkov, M.; Joshi, Y. C.; Seetha, S.; Chakradhari, N. K.; Mary, D. L.; Girish, V.; Ashoka, B. N.

2012-08-01

36

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

37

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

NASA Astrophysics Data System (ADS)

This work presents the characterization of 2,3-difluorophenylboronic acid (abbreviated as 2,3-DFPBA, C6H3B(OH)2F2) by quantum chemical calculations and spectral techniques. The spectroscopic properties were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C 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 1H and 13C 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. 13C and 1H 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.

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

2012-11-01

38

Benford Analysis: A useful paradigm for spectroscopic analysis  

E-print Network

Benford's law is a statistical inference to predict the frequency of significant digits in naturally occurring numerical databases. In such databases this law predicts a higher occurrence of the digit 1 in the most significant place and decreasing occurrences to other larger digits. Although counter-intuitive at first sight, Benford's law has seen applications in a wide variety of fields like physics, earth-science, biology, finance etc. In this work, we have explored the use of Benford's law for various spectroscopic applications. Although, we use NMR signals as our databases, the methods described here may also be extended to other spectroscopic techniques. In particular, with the help of Benford analysis, we demonstrate the detection of weak NMR signals and spectral corrections. We also explore a potential application of Benford analysis in the image-processing of MRI data.

Bhole, Gaurav; Mahesh, T S

2014-01-01

39

Vibrational spectroscopic studies of mesna and dimesna.  

PubMed

Raman, and infrared spectra of mesna and dimesna have been collected in the present spectroscopic studies. Based on the group frequencies, relative intensities and Raman depolarization measurements, some vibrational assignments have been suggested. For both mesna and dimesna, at least two rotational conformers have been identified. Adsorption behavior was investigated from the recorded surface-enhanced Raman scattering (SERS) spectra. It was found that both mesna and dimesna adsorbed as thiolate on silver sol particles with the cleavage of the S-H bond in mesna and the S-S bond in dimesna. For the adsorbed thiolate, two conformers existed in the adsorption state. PMID:12736065

Li, Ying-Sing; Wang, Yu; Church, Jeffrey S; Garzena, Fabio; Zhang, Zanxing; An, Danqui

2003-06-01

40

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

41

Spectroscopic study of laser irradiated chromatin  

NASA Astrophysics Data System (ADS)

The effects of three UV excimer laser radiations, with wavelengths of 193, 248 and 282 nm respectively, on the structure of chromatin (the complex of deoxyribonucleic acid with proteins that exists in eukaryotic cells nuclei) were investigated. The chromatin was extracted from livers of Winstar rats. The spectroscopic methods used are: fluorescence (Förster) resonance energy transfer (FRET), time resolved fluorescence and steady-state fluorescence. A chromatin deoxyribonucleic acid radiolysis, a chromatin proteins damage and a change of the global chromatin structure on lasers action were indicated by this study. It exists some small differences between the actions of these three laser radiations.

Radu, Liliana; Mihailescu, I.; Gazdaru, Doina; Preoteasa, V.

2013-04-01

42

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

43

Spectroscopic analysis and charge transfer interaction studies of 4-benzyloxy-2-nitroaniline insecticide: a density functional theoretical approach.  

PubMed

A widespread exploration on the intra-molecular charge transfer interaction through an efficient ?-conjugated path from a strong electron-donor group (amino) to a strong electron-acceptor group (nitro) has been carried out using FTIR, FT-Raman, UV-Vis, fluorescence and NMR spectra on insecticide compound 4-benzyloxy-2-nitroaniline. Density functional theory method is used to determine optimized molecular geometry, harmonic vibrational wavenumbers and intensities using 6-311G(d,p) basis set by means of Gaussian 09W program suit. A comprehensive investigation on the sp(2) to sp(3) hybridization and non-planarity property has been performed. Natural bond orbital analysis is used to study the existence of C-H?O, N-H?O and C-H?? proper and improper hydrogen bonds. The HOMO and LUMO analysis reveals the possibility of charge transfer within the molecule. A complete assignment of the experimental absorption peaks in the ultraviolet region has also been performed. Isotropic chemical shifts of (13)C, (1)H, (15)N and (18)O NMR and nuclear spin-spin coupling constants have been computed using the gauge-invariant atomic orbital method. The biological activity of substituent amino and nitro groups are evident from the hydrogen bonds through which the target amino acids are linked to the drug as evidenced from molecular docking. PMID:25216343

Arul Dhas, D; Hubert Joe, I; Roy, S D D; Balachandran, S

2015-01-25

44

?-Bromo-p-tolunitrile: Conformational stability, vibrational spectroscopic studies, NBO analysis and thermodynamic functions based on density functional theory  

NASA Astrophysics Data System (ADS)

In this work, the experimental and theoretical study on molecular structure and vibrational spectra of ?-bromo-p-tolunitrile (?BpTN) are studied. The energies of possible conformers obtained from DFT theory with 6-31+G(d) and 6-311++G(d) basis sets identified the most stable conformer of ?BpTN as C2 conformer. The differences between the observed and scaled wavenumber values of most of the fundamentals are very small in B3LYP/6-311++G(d) than B3LYP/6-31+G(d). The first hyperpolarizability (?0) of this novel molecular system and related properties (? and ?) of ?BpTN are calculated using B3LYP/6-31+G(d) and B3LYP/6-311++G(d) method on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital analysis. The results show that charge in electron density (ED) in the ?* and ?* antibonding orbital and second order delocalization energies conforms the occurrence of intramolecular charge transfer within the molecule. The calculated HOMO and LUMO energies show that charge transfer occurs in the molecule. Finally the vibrations of Ctbnd N and CH2sbnd Br groups coupled with skeletal vibrations are also investigated.

Janaki, A.; Balachandran, V.; Lakshmi, A.

2013-06-01

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); Bigio, Irving J. (Los Alamos, NM); Loree, Thomas R. (Santa Fe, NM)

1994-01-01

46

Vibrational spectroscopic analysis of breast calcifications and surrounding tissue  

NASA Astrophysics Data System (ADS)

Breast calcifications can be found in both benign and malignant lesions and the composition of these calcifications can indicate the possible disease state. Calcium oxalate dihydrate (COD) is found to be associated with benign lesions, however calcium hydroxyapatite (HAP) is found mainly in malignant tissue. As current practices such as mammography and histopathology examine the morphology of the specimen, they can not reliably distinguish between the two types of calcification, which frequently are the only features that indicate the presence of a cancerous lesion. Therefore this information can be used to make a simplistic diagnostic decision, if the biochemistry of the calcifications can be probed. Studies have been performed utilising the synchrotron mid-IR beamline at Daresbury (UK) to probe the local tissue biochemistry around breast calcifications. Raman and FTIR spectroscopic analysis of the same specimen have also been performed and spectral maps have been collected of areas in and around calcifications. Principal component analysis was used to identify the major differences in the spectra across each map. FTIR and Raman spectroscopic techniques provide complementary biochemical information and demonstrate great potential for determining biochemical changes in calcified breast tissue. Further studies will be carried out using these techniques to investigate the formation mechanisms and effects of hydroxyapatite on breast tissue and to correlate the type of hydroxyapatite present to the tumour grade.

Baker, Rebecca N.; Smith, Jennifer; Rogers, Keith D.; Stone, Nicholas

2006-02-01

47

Fundamental spectroscopic studies of carbenes and hydrocarbon radicals  

SciTech Connect

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

Gottlieb, C.A.; Thaddeus, P. [Harvard Univ., Cambridge, MA (United States)

1993-12-01

48

Photoacoustic spectroscopic studies of polycyclic aromatic hydrocarbons  

NASA Astrophysics Data System (ADS)

Because of their involvement in environmental pollutants, in carcinogenic activity, plastics, pharmaceuticals, synthesis of some laser dyes and presence in interstellar space etc., Polycyclic aromatic hydrocarbons (PAHs) are important. As their structure and properties can be varied systematically, they form a beautiful class of molecules for experimental and quantum chemical investigations. These molecules are being studied for last several years by using conventional spectroscopy. In recent years, Photoacoustic (PA) spectroscopy has emerged as a new non-destructive technique with unique capability and sensitivity. The PA effect is the process of generation of acoustic waves in a sample resulting from the absorption of photons. This technique not only reveals non- radiative transitions but also provides information about forbidden singlet-triplet transitions which are not observed normally by the conventional spectroscopy. The present paper deals with the spectroscopic studies of some PAH molecules by PA spectroscopy in the region 250 - 400 nm. The CNDO/S-CI method is used to calculate the electronic transitions with the optimized geometries. A good agreement is found between the experimental and calculated results.

Zaidi, Zahid H.; Kumar, Pardeep; Garg, R. K.

1999-02-01

49

NMR-spectroscopic analysis of mixtures: from structure to function  

PubMed Central

NMR spectroscopy as a particularly information-rich method offers unique opportunities for improving the structural and functional characterization of metabolomes, which will be essential for advancing the understanding of many biological processes. Whereas traditionally NMR spectroscopy was mostly relegated to the characterization of pure compounds, the last few years have seen a surge of interest in using NMR spectroscopic techniques for characterizing complex metabolite mixtures. Development of new methods was motivated partly by the realization that using NMR for the analysis of metabolite mixtures can help identify otherwise inaccessible small molecules, for example compounds that are prone to chemical decomposition and thus cannot be isolated. Furthermore, comparative metabolomics and statistical analyses of NMR-spectra have proven highly effective at identifying novel and known metabolites that correlate with changes in genotype or phenotype. In this review, we provide an overview of the range of NMR spectroscopic techniques recently developed for characterizing metabolite mixtures, including methods used in discovery-oriented natural product chemistry, in the study of metabolite biosynthesis and function, or for comparative analyses of entire metabolomes. PMID:21071261

Forseth, Ry R.; Schroeder, Frank C.

2010-01-01

50

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

51

Indentation device for in situ Raman spectroscopic and optical studies  

NASA Astrophysics Data System (ADS)

Instrumented indentation is a widely used technique to study the mechanical behavior of materials at small length scales. Mechanical tests of bulk materials, microscopic, and spectroscopic studies may be conducted to complement indentation and enable the determination of the kinetics and physics involved in the mechanical deformation of materials at the crystallographic and molecular level, e.g., strain build-up in crystal lattices, phase transformations, and changes in crystallinity or orientation. However, many of these phenomena occurring during indentation can only be observed in their entirety and analyzed in depth under in situ conditions. This paper describes the design, calibration, and operation of an indentation device that is coupled with a Raman microscope to conduct in situ spectroscopic and optical analysis of mechanically deformed regions of Raman-active, transparent bulk material, thin films or fibers under contact loading. The capabilities of the presented device are demonstrated by in situ studies of the indentation-induced phase transformations of Si thin films and modifications of molecular conformations in high density polyethylene films.

Gerbig, Y. B.; Michaels, C. A.; Forster, A. M.; Hettenhouser, J. W.; Byrd, W. E.; Morris, D. J.; Cook, R. F.

2012-12-01

52

Optical trapping and binding in air: Imaging and spectroscopic analysis  

SciTech Connect

We report on an experimental study of direct and spectroscopic imaging of optically trapped Mie droplets in air. The scattering of the trapping beams gives glare points at the droplets' azimuths. Spectroscopic measurements involving polarized light are performed to precisely determine both the droplet sizes and refraction index using Mie scattering theory. Experimental pictures are compared to rigorous numerical simulations. We also include some results on imaging of whispering gallery resonances and conclude with a brief discussion on the possibility of efficiently exciting whispering gallery resonances via radiative coupling.

Guillon, Marc [Laboratoire d'Interferometrie Stellaire et Exoplanetaire, Observatoire de Haute Provence, 04870 Saint Michel l'Observatoire (France); Stout, Brian [Case 161, Institut Fresnel, Faculte des Sciences et Techniques de St. Jerome, 13397 Marseille cedex 20 (France)

2008-02-15

53

ALS 2883: Analysis of spectroscopic features  

NASA Astrophysics Data System (ADS)

ALS 2883 (RA 13^{h} 02^{m} 47^{s}, DEC -63^{o} 50' 08'', M_{v} 10.1) is the first known radio pulsar with an emission B-type companion system, discovered in 1992. The Be companion of ALS 2883 has all line profiles in the visible range in emission. This emission is a common hallmark among many Be stars, and this effect is thought to be due to the presence of a circumstellar environment. Also, the star is orbiting a X-ray source as has been detected by the XMM-Newton Science Operation Center. In this study, we present the observations of ALS 2883 made at the OPD/LNA 1.60 m telescope with the Coudé spectrograph in the range 4000 to 5000 Å and S/N simeq 200, performed in April 2011. First-order estimations of T_{eff} and log g parameters have been performed through Johnson's UBV and JHK photometric calibrations. Projected rotation velocity V sin i has been estimated through the mean of the first zeroes of the Fourier transforms of neutral helium rotation profiles adopting linear, quadratic and square-root limb-darkening laws. The physical conditions of the circumstellar envelope were estimated through the solution of the radiative transport equation assuming local thermodynamic equilibrium within a disk-shaped circumstellar environment with a Keplerian velocity field. The radiative transport equation is solved assuming the Roche model as a boundary condition in the circumstellar environment. Iterating the computations with a downhill-simplex algorithm, this analysis leads to a best solution for an envelope with T simeq 9500 K, gas density ? simeq 2 × 10^{-15} g.cm^{-3}, internal radius r_{i} simeq 8 R_{odot} and external radius r_e simeq 30 R_{odot}, rotating with V_{rot} simeq 140 km.s^{-1} and expanding with V_{exp} simeq 90 km.s^{-1}.

Silva, A. R.; Levenhagen, R. S.; Künzel, R.; Leister, N. V.

2014-10-01

54

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

55

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. PMID:20177449

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

2009-01-01

56

Statistical analysis of single-lined red giant spectroscopic binaries  

Microsoft Academic Search

This article reports a statistical analysis of the orbital elements (period, eccentricity, mass function) performed on a sample of 194 single-lined red giant spectroscopic binaries. From the eccentricity-period diagram, the authors deduce a circularization cut-off period of 70 days and find an eccentricity-period correlation that seemingly does not result from an observational bias. With the aid of two complementary methods,

H. M. J. Boffin; G. Paulus; N. Cerf

1992-01-01

57

Detailed Spectroscopic and Photometric Analysis of DQ White Dwarfs  

E-print Network

We present an analysis of spectroscopic and photometric data for cool DQ white dwarfs based on improved model atmosphere calculations. In particular, we revise the atmospheric parameters of the trigonometric parallax sample of Bergeron et al.(2001), and discuss the astrophysical implications on the temperature scale and mean mass, as well as the chemical evolution of these stars. We also analyze 40 new DQ stars discovered in the first data release of the Sloan Digital Sky Survey.

P. Dufour; P. Bergeron; G. Fontaine

2005-03-04

58

Quantitative spectroscopic studies of a pulsed plasma microthruster  

NASA Astrophysics Data System (ADS)

The absolute intensity of the emission spectra emitted from a PPT plume was studied from both experimental measurements and theoretical analysis to investigate its interference with an optical sensor/signal. The results were also used to estimate the absolute radiant-energy emitted from the PPT plume to compare with the input energy for the energy-budget analysis. Initially the radiating species in the PPT plume were identified by the spectroscopic measurements. For the identified species, the absolute intensity was obtained in three methods. In the first method, the intensity was experimentally measured with the quantitative spectroscopic apparatus to provide the experimental intensity. In the second method, the intensity was theoretically calculated with the experimental results assuming the observed plasma to be spatially uniform and temporally constant for simplification to provide the spatially and temporally uniform (STU) semi-empirical theoretical intensity. In the third method, the intensity was theoretically calculated independently from the experimental results using the MACH2 magnetohydrodynamic code to provide the spatially and temporally nonuniform (STN) fully theoretical intensity. The STU theoretical intensity has reasonable agreement with the experimental intensity to capture the trend although the STU values are larger by up to four times. This discrepancy was reduced by STN theoretical intensity which predicted well the experimental value. Using the result of the experimental intensity and the STN theoretical intensity, the radiant energy was estimated. The experimental and the theoretical radiant energies increase with the input energy in an approximately linear fashion. The result indicates that the radiative loss due to the spontaneous line emission in the range of 400 to 700 nm is at most 0.02% of the input energy. The comparisons of absolute intensity measurements and calculations of radiant energy based on MACH2 MHD simulations indicate that such simulations can provide adequate guides for estimating the amount of radiation from PPTs.

Umeki, Tomokazu

2001-06-01

59

jSIPRO - analysis tool for magnetic resonance spectroscopic imaging.  

PubMed

Magnetic resonance spectroscopic imaging (MRSI) involves a huge number of spectra to be processed and analyzed. Several tools enabling MRSI data processing have been developed and widely used. However, the processing programs primarily focus on sophisticated spectra processing and offer limited support for the analysis of the calculated spectroscopic maps. In this paper the jSIPRO (java Spectroscopic Imaging PROcessing) program is presented, which is a java-based graphical interface enabling post-processing, viewing, analysis and result reporting of MRSI data. Interactive graphical processing as well as protocol controlled batch processing are available in jSIPRO. jSIPRO does not contain a built-in fitting program. Instead, it makes use of fitting programs from third parties and manages the data flows. Currently, automatic spectra processing using LCModel, TARQUIN and jMRUI programs are supported. Concentration and error values, fitted spectra, metabolite images and various parametric maps can be viewed for each calculated dataset. Metabolite images can be exported in the DICOM format either for archiving purposes or for the use in neurosurgery navigation systems. PMID:23870172

Jiru, Filip; Skoch, Antonin; Wagnerova, Dita; Dezortova, Monika; Hajek, Milan

2013-10-01

60

Spectroscopic analysis of biologically synthesized silver nanoparticles under clinorotation  

NASA Astrophysics Data System (ADS)

Nanoparticles are one of the hot topics of research due to their size dependent optical, electrical and magnetic properties & their anti-bacterial and anti-fungal nature. Synthesis of nano particles can be done by various physical and chemical methods. However, Biosynthesis of nanoparticles is environment friendly, can take place around room temperature, and require little intervention or input of energy. In the present study, the synthesis of silver nanoparticles (AgNPs) using bacteria and the effect of clinorotation on rate of synthesis is discussed. The freshly grown bacterial isolate was inoculated in to 250-ml Erlenmeyer flask containing 50 ml sterile nutrient broth (LB). The cultured flasks were incubated in a shaker at 120 rpm for 24 h at 370C. Culture was centrifuged at 10,000 rpm for 10 min. The supernatant was used for carrying extracellular production of silver nanoparticles by mixing it with 5mM AgNO3 solution. The above solution was clinorotated at 2 rpm for 24 h. The synthesis was carried out at 60oC. Visual observation was conducted periodically to check for the nanoparticles formation in normal gravity as well as under clinorotation. UV-visible spectroscopic analysis showed that rate of synthesis was faster in case of clinorotated sample than control. Further, the results of FTIR and XRD characterization will be discussed.

Jagtap, Sagar; Vidyasagar, Pandit; Ghemud, Vipul; Dixit, Jyotsana

61

Nonplanar property study of antifungal agent tolnaftate-spectroscopic approach.  

PubMed

Vibrational analysis of the thionocarbamate fungicide tolnaftate which is antidermatophytic, antitrichophytic and antimycotic agent, primarily inhibits the ergosterol biosynthesis in the fungus, was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features, harmonic vibrational wavenumbers and torsional potential energy surface (PES) scan studies have been computed using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bonding orbital (NBO) analysis and optimized molecular structure show the clear evidence for electronic interaction of thionocarbamate group with aromatic ring. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C-C stretching mode in the phenyl and naphthalene ring provide evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity as a fungicide. PMID:21565546

Dhas, D Arul; Joe, I Hubert; Roy, S D D; Balachandran, S

2011-09-01

62

A spectroscopic analysis of the chemically peculiar star HD207561  

E-print Network

In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is s...

Joshi, S; Martinez, P; Sachkov, M; Joshi, Y C; Seetha, S; Chakradhari, N K; Mary, D L; Girish, V; Ashoka, B N

2012-01-01

63

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

64

Infrared Imaging, Spectroscopic, and Photometric Studies of Comets  

NASA Technical Reports Server (NTRS)

We have continued our program of infrared (IR) photometric, imaging, spectroscopic, and polarimetric temporal observations of comets to study the properties of comet dust and comet nuclei. During the first two years we digitized our IR data base on P/Halley and other recent comets to facilitate further analysis and comparison with other data bases, and found compelling evidence for the emission of a burst of small grains from P/Halley's nucleus at perihelion. We reported imaging and photometric observations of Comets Austin 1990 V and Swift-Tuttle 1992. The Swift-Tuttle 1992t observations included IR photometry, several 7-14 micron long-slit spectra of the coma and a time-sequence of more than 150 10 micron broadband images of the coma. An analysis of near-IR images of the inner coma of P/Halley obtained on three consecutive nights in 1986 March showed sunwardjets. We completed our analysis of IR imaging spectrosco-photometric data on comets. We also obtained observations of Comets Hyakutake 1996 B2 and Hale/Bopp 1995 01. We obtained infrared imaging, photometric, spectroscopic and polarimetric temporal observations of bright comets using a network of five telescopes, with emphasis on simultaneous observations of comets at many wavelengths with different instruments. Our program offers several unique advantages: 1) rapid observational response to new comets with dedicated infrared telescopes; 2) observations within a few degrees of the sun when comets are near perihelion and 3) access to advanced infrared array imagers and spectrometers. In particular, reduction, analysis, publication and archiving of our Jupiter/sl-9 and Comet Hyakutake infrared data received special emphasis. Instrumentation development included installation of the latest version of the innovative FORTH telescope control and a data acquisition system that enables us to control three telescopes remotely by telephone from anywhere in the world for comet observations in broad daylight. We have acquired more than 3000 256x256 images totaling nearly two gigabytes of data detailing the near-IR development of the impact sites of the S-L9 fragments on Jupiter. These data were obtained using the University of Rochester Imaging IR Camera at the cassegrain focus of the 92" at WIRO. The WIRO data set covers 8 days and is, to our knowledge, one of the most extensive observational records of the S-L/Jupiter encounter obtained by any ground-based telescope. This program benefitted from the compilation during these last few months of an upgrade to the data acquisition program at WIRO with support of this NASA contract.

Gehrz, Robert D.

1997-01-01

65

Spectroscopic studies of alkaline activated slag geopolymers  

NASA Astrophysics Data System (ADS)

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

Mozgawa, W.; Deja, J.

2009-04-01

66

Study of the interaction of an anticancer drug with human and bovine serum albumin: Spectroscopic approach  

Microsoft Academic Search

The interactions between gemcitabine hydrochloride (GEM) and bovine serum albumin (BSA) or human serum albumin (HSA) have been studied by spectroscopic techniques. By the analysis of fluorescence spectrum and fluorescence intensity, it was observed that the GEM has a strong ability to quench the intrinsic fluorescence of both BSA and HSA through a static quenching procedure. The association constants of

P. B. Kandagal; S. Ashoka; J. Seetharamappa; S. M. T. Shaikh; Y. Jadegoud; O. B. Ijare

2006-01-01

67

Molecular structure, spectroscopic studies (FTIR, FT-Raman and NMR) and HOMO-LUMO analysis of 6-chloro-o-cresol and 4-chloro-3-methyl phenol by density functional theoretical study  

NASA Astrophysics Data System (ADS)

In this work, the experimental and theoretical vibrational spectra of 6-chloro-o-cresol (COC) and 4-chloro-3-methylphenol (CMP) have been studied. FTIR and FT-Raman spectra of the title compounds in the solid phase are recorded in the region 4000-400 cm-1 and 4000-50 cm-1, respectively. The structural and spectroscopic data of the molecules in the ground state are calculated by using density functional methods (B3LYP) with 6-31G* basis set combinations. The calculated vibrational frequencies are scaled by normal coordinate analysis based on a scaled quantum mechanical force field. The obtained values are compared with experimental FTIR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete vibrational assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The results of 13C and 1H NMR chemical shift are compared with the experimental values.

Krishnakumar, V.; Kumar, M.; Prabavathi, N.; Mathammal, R.

2012-11-01

68

A photometric and spectroscopic study of BG Canis Minoris  

Microsoft Academic Search

The photometric and spectroscopic analysis presented here has revealed new observational features in the Intermediate Polar BG CMi. We have found a strong variability of the dominant light pulsations, rotational (913s) and orbital (3.23hr), on a timescale of years. Variations in the amplitude of the spin pulsation with epoch generally appear to be anti-correlated with that of the orbital modulation

D. de Martino; M. Mouchet; J. M. Bonnet-Bidaud; R. Vio; S. R. Rosen; K. Mukai; T. Augusteijn; M. A. Garlick

1995-01-01

69

Novel high-resolved spectroscopic studies of positive streamer corona  

Microsoft Academic Search

We have developed a fully self-consistent method of diagnostics of streamer discharge plasmas based on analysis of absolute intensities of the second positive (SPS) and first negative (FNS) systems of molecular nitrogen. The theory of the method combines a spectroscopic technique for calculation of temporal waveforms of the nitrogen absolute SPS and FNS (0,0)-band emission and a self-consistent semi-analytical parametric

Yuri V. Shcherbakov

2007-01-01

70

A Detailed Spectroscopic and Photometric Analysis of DQ White Dwarfs  

E-print Network

We present an analysis of spectroscopic and photometric observations of cool DQ white dwarfs based on improved model atmosphere calculations. In particular, we revise the atmospheric parameters of the trigonometric parallax sample of Bergeron, Leggett, & Ruiz, and discuss the astrophysical implications on the temperature scale and mean mass, as well as the chemical evolution of these stars. We also analyze 40 new DQ stars discovered in the first data release of the Sloan Digital Sky Survey. Our analysis confirms that effective temperatures derived from model atmospheres including carbon are significantly lower than the temperatures obtained from pure helium models. Similarly the mean mass of the trigonometric parallax sample, = 0.62 Mo, is significantly lower than that obtained from pure helium models, = 0.73 Mo, and more consistent with the spectroscopic mean mass of DB stars, = 0.59 Mo, the most likely progenitors of DQ white dwarfs. We find that DQ stars form a remarkably well defined sequence in a carbon abundance versus effective temperature diagram; below Teff~10,000 K, carbon pollution decreases monotonically with decreasing effective temperature. Improved evolutionary models including diffusion and connecting to the PG 1159 phase are used to infer a typical value for the thickness of the helium layer M_He/M_* between 10^{-3} and 10^{-2}, compatible with the predictions of post-AGB models.

P. Dufour; P. Bergeron; G. Fontaine

2005-03-21

71

Spectroscopic analysis of vermicompost for determination of nutritional quality.  

PubMed

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

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

2015-01-25

72

Raman spectroscopic studies of the cure of dicyclopentadiene (DCPD)  

NASA Astrophysics Data System (ADS)

The cure of polydicyclopentadiene conducted by ring-opening metathesis polymerisation in the presence of a Grubbs catalyst was studied using non-invasive Raman spectroscopy. The spectra of the monomer precursor and polymerised product were fully characterised and all stages of polymerisation monitored. Because of the monomer's high reactivity, the cure process is adaptable to reaction injection moulding and reactive rotational moulding. The viscosity of the dicyclopentadiene undergoes a rapid change at the beginning of the polymerisation process and it is critical that the induction time of the viscosity increase is determined and controlled for successful manufacturing. The results from this work show non-invasive Raman spectroscopic monitoring to be an effective method for monitoring the degree of cure, paving the way for possible implementation of the technique as a method of real-time analysis for control and optimisation during reactive processing. Agreement is shown between Raman measurements and ultrasonic time of flight data acquired during the initial induction period of the curing process.

Barnes, S. E.; Brown, E. C.; Corrigan, N.; Coates, P. D.; Harkin-Jones, E.; Edwards, H. G. M.

2005-10-01

73

Inhibition of urinary calculi -- a spectroscopic study  

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

74

MULTIBAND PHOTOMETRIC AND SPECTROSCOPIC ANALYSIS OF HV Cnc  

SciTech Connect

In this paper, radial velocity and VI- and JHK{sub S} - (Two Micron All Sky Survey) band photometric data of the detached system HV Cnc have been analyzed. The primary component of HV Cnc, which is a member of the M67 cluster, is suspected to be either a blue straggler or turn-off star. The system is a single-lined spectroscopic binary and its light curve shows a total eclipse. Spectroscopic observations of the system revealed the third component, which shows contribution to the total light of the system. Light curve and radial velocity data have been analyzed using the Wilson-Devinney (W-D) code and JHK{sub S} filter definitions computed for the W-D code in this work. Our analysis shows that the mass and radius of the primary and secondary components are 1.31 M {sub ?}, 0.52 M {sub ?}, 1.87 R {sub ?}, and 0.48 R {sub ?}, respectively. All results are compared with previously published literature values and discussed.

Gökay, G.; Gürol, B.; Derman, E., E-mail: ggokay@science.ankara.edu.tr [Astronomy and Space Sciences Department, Faculty of Science, Ankara University, 06100 Tando?an, Ankara (Turkey)

2013-11-01

75

Spectroscopic studies of metal growth on oxides  

E-print Network

of metal clusters on well-defined oxide surfaces. In this work, the nucleation and growth modes of Ag on TiO?(110)(1x1) and (1x2) surfaces, Ag on ultra-thin Al?O? films, and Au on ultra-thin SiO? films were studied by scanning tunneling microscopy (STM...

Luo, Kai

2012-06-07

76

Spectroscopic Studies of Fluoranthene and 3-Nitrofluoranthene  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are known byproducts of anthropogenic sources including incomplete combustion of fossil fuels. They are known to be teratogenic, mutagenic and carcinogenic. This study investigated the spectral properties of fluoranthene and 3- nitrofluoranthene using NMR, UV-Vis and infrared techniques. The acquisition of spectral data provides a means to identify these compounds in mixtures and can be used

Matthew Parks

2009-01-01

77

Tunneling spectroscopic study of finite superlattices  

NASA Astrophysics Data System (ADS)

We present a tunneling density of states study of the transition from a superlattice miniband to a sequential coupled well structure. We have observed by tunneling spectroscopy the eigenstates of a finite superlattice system far below the Stark localization threshold. The transition from an indistinguishable miniband to a coupled well structure is experimentally found to be 2.5 meV ?W(miniband width)/n(? periods) ?10.5 meV.

Aggarwal, R. J.; Reed, M. A.; Frensley, W. R.; Kao, Y.-C.; Luscombe, J. H.

1990-08-01

78

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

79

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

80

Terahertz spectroscopic study of benzodiazepine sedative hypnotics  

NASA Astrophysics Data System (ADS)

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

Deng, Fusheng; Shen, Jingling; Wang, Xianfeng

2011-08-01

81

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

82

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

83

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

84

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

85

Spectroscopic study of biologically active glasses  

NASA Astrophysics Data System (ADS)

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

Szumera, M.; Wac?awska, I.; Mozgawa, W.; Sitarz, M.

2005-06-01

86

Integrated Spectroscopic Studies of Anhydrous Sulfate Minerals  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

87

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

88

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. PMID:24298417

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

2013-01-01

89

Spectroscopic studies of cold, gas-phase biomolecular ions  

NASA Astrophysics Data System (ADS)

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

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

90

Spectroscopic studies of protein folding: Linear and nonlinear methods  

PubMed Central

Although protein folding is a simple outcome of the underlying thermodynamics, arriving at a quantitative and predictive understanding of how proteins fold nevertheless poses huge challenges. Therefore, both advanced experimental and computational methods are continuously being developed and refined to probe and reveal the atomistic details of protein folding dynamics and mechanisms. Herein, we provide a concise review of recent developments in spectroscopic studies of protein folding, with a focus on new triggering and probing methods. In particular, we describe several laser-based techniques for triggering protein folding/unfolding on the picosecond and/or nanosecond timescales and various linear and nonlinear spectroscopic techniques for interrogating protein conformations, conformational transitions, and dynamics. PMID:22109973

Serrano, Arnaldo L; Waegele, Matthias M; Gai, Feng

2012-01-01

91

Spectroscopic and dynamical studies of highly energized small polyatomic molecules  

SciTech Connect

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

Field, R.W.; Silbey, R.J. [Massachusetts Institute of Technology, Cambridge (United States)

1993-12-01

92

Spectroscopic Analysis of Rock Mineral—Garnet of South Kerala  

NASA Astrophysics Data System (ADS)

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 is inferred from the XRF that the sample contains large concentration of Tungsten [WO3-22%] besides Silicon [SiO2-7-9%], Iron [Fe2O3-55%] etc.. IR spectra in the region 2800-3600 cm-1 indicates absorption pattern attributable to OH structurally bound within the Garnet. The spectral bands corresponding to the various elements present in the garnet sample such as Si, Al, Fe, Mg etc. have been identified from their Raman and IR spectra. The vibrational spectral analysis further confirms that the garnet under investigation has crystallographically non equivalent SiO2 tetrahedral.

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

2008-11-01

93

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

Microsoft Academic Search

This paper reports the results of the characterization of red soils in relation to the sorption of H2S from coal gas at 500°C by spectroscopic techniques in order to provide more information on red soils’ structural change both before and after reaction. In addition, by-products analysis has also been studied using Fourier transform infrared (FTIR) spectroscopy. Before and after the

T. H. Ko; H. Chu

2005-01-01

94

Raman spectroscopic studies on p-terphenyl under high pressure  

NASA Astrophysics Data System (ADS)

High-pressure Raman scattering studies are performed on p-terphenyl up to 5 GPa. The Raman activities of different symmetric molecules were analyzed by means of group theory methods. A phase transition was detected at 1.3 GPa from changes in the slope on plots of frequency versus pressure. The diminishing of internal modes indicated that the molecule symmetry transformed from C2 to D2h. This is an effective method for detecting planar molecular structure of p-terphenyl by ring-ring stretching vibration mode, which can provide a new spectroscopic evidence of planar conjugated polyphenyl molecular conformation.

Liu, Tianyuan; Xu, Shengnan; Sun, Chenglin; Zhou, Mi

2014-11-01

95

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

96

Raman spectroscopic study of a genetically altered kidney cell  

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

97

Albumin adsorption on oxide thin films studied by spectroscopic ellipsometry  

NASA Astrophysics Data System (ADS)

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 Bovine Serum Albumin (BSA) adsorption, as a first step into the development of an initial in vitro test of the films biocompatibility, based on standardized protein adsorption essays. The films were immersed into BSA solutions with different protein concentrations and protein adsorption was monitored in situ by dynamic ellipsometry; the adsorption-rate was dependent on the solution concentration and the immersion time. The overall BSA adsorption was studied in situ using spectroscopic ellipsometry and it was found to be influenced by the wettability of the films; larger BSA adsorption occurred on the more hydrophobic surface, the ZrO 2 film. On the Ta 2O 5, Nb 2O 5 and TiO 2 films, hydrophilic surfaces, the overall BSA adsorption increased with the surface roughness or the polar component of the surface energy.

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

2011-12-01

98

Spectroscopic studies of carbon impurities in PISCES-A  

SciTech Connect

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

Ra, Y.; Hirooka, Y.; Leung, W.K.; Conn, R.W. (California Univ., Los Angeles, CA (USA). Inst. of Plasma and Fusion Research); Pospieszczyk, A. (Association Euratom-Kernforschungsanlage Juelich (Germany, F.R.). Inst. fuer Plasmaphysik)

1989-08-01

99

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

100

Experimental and theoretical spectroscopic studies, HOMO-LUMO, NBO and NLMO analysis of 3,5-dibromo-2,6-dimethoxy pyridine  

NASA Astrophysics Data System (ADS)

The molecular vibrations of 3,5-dibromo-2,6-dimethoxy pyridine (DBDMP) have been investigated in polycrystalline sample, at room temperature, by Fourier transform infrared (FT-IR) and FT-Raman spectroscopies. The vibrational frequencies of the fundamental modes of the compound have been precisely assigned and theoretical results were compared with the experimental vibrations. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman activities were obtained by means of ab initio and density functional theory (DFT) gradient calculations, using 6-311++G(d,p) basis set. Thermodynamic properties like entropy, heat capacity and zero point energy have been calculated for the molecule. 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. The Molecular Electrostatic Potential (MEP) analysis reveals the sites for electrophilic attack and nucleophilic reactions in the molecule.

Xavier, R. John; Gobinath, E.

2012-11-01

101

Quantum mechanical study of the structure and spectroscopic, first order hyperpolarizability, Fukui function, NBO, normal coordinate analysis of Phenyl-N-(4-Methyl Phenyl) Nitrone  

NASA Astrophysics Data System (ADS)

The title compound, Phenyl-N-(4-Methyl Phenyl) Nitrone (PN4MPN) was synthesized and characterized by FT-IR, FT-Raman and 1HNMR, 13CNMR 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.

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

2013-08-01

102

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

103

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 4000-400 cm(-1) and 3500-100 cm(-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

104

Spectroscopic studies in a nonequilibrium hypersonic gas flow  

NASA Astrophysics Data System (ADS)

Self-luminescent hypersonic air flow with additions of sodium and potassium formed by the secondary nozzle of an MHD accelerator wind tunnel was studied spectroscopically, with panoramic measurements of the velocity and temperature fields conducted within a single run. The flow had a mean velocity of 2-8 m/s and a temperature of 1000-30,000 K; the pressure in the test chamber was 0.01 atm; the jet had a lifetime of 0.2 s and a cross section of 60-360 sq cm. The measurement principle, the general design of the panoramic spectrometer, experimental setup and data processing, and results of the study are discussed.

Kniazev, A. A.; Lerner, N. V.; Svinolupov, K. I.

1992-04-01

105

Vibrational spectroscopic studies, normal co-ordinate analysis, first order hyperpolarizability, HOMO-LUMO of midodrine by using density functional methods.  

PubMed

The FTIR (4000-400 cm(-1)), FT-Raman (4000-100 cm(-1)) and UV-Visible (400-200 nm) spectra of midodrine were recorded in the condensed state. The complete vibrational frequencies, optimized geometry, intensity of vibrational bands and atomic charges were obtained by using Density Functional Theory (DFT) with the help of 6-311++G(d,p) basis set. The first order hyperpolarizability (?) and related properties (?, ? and ??) of this molecular system were calculated by using DFT/6-311++G(d,p) method based on the finite-field approach. 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 methodology. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using NBO analysis. From the recorded UV-Visible spectrum, the electronic properties such as excitation energies, oscillator strength and wavelength are calculated by DFT in water and gas methods using 6-311++G(d,p) basis set. The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. Besides MEP, NLO and thermodynamic properties were also calculated and interpreted. The electron density-based local reactivity descriptor such as Fukui functions was calculated to explain the chemical selectivity or reactivity site in midodrine. PMID:25011041

Shahidha, R; Al-Saadi, Abdulaziz A; Muthu, S

2015-01-01

106

Spectroscopic study of the open cluster NGC 6811  

NASA Astrophysics Data System (ADS)

The NASA space telescope Kepler has provided unprecedented time series observations which have revolutionized the field of asteroseismology, i.e. the use of stellar oscillations to probe the interior of stars. The Kepler-data include observations of stars in open clusters, which are particularly interesting for asteroseismology. One of the clusters observed with Kepler is NGC 6811, which is the target of this paper. However, apart from high-precision time series observations, sounding the interiors of stars in open clusters by means of asteroseismology also requires accurate and precise atmospheric parameters as well as cluster membership indicators for the individual stars. We use medium-resolution (R ˜ 25 000) spectroscopic observations, and three independent analysis methods, to derive effective temperatures, surface gravities, metallicities, projected rotational velocities and radial velocities, for 15 stars in the field of the open cluster NGC 6811. We discover two double-lined and three single-lined spectroscopic binaries. Eight stars are classified as either certain or very probable cluster members, and three stars are classified as non-members. For four stars, cluster membership could not been assessed. Five of the observed stars are G-type giants which are located in the colour-magnitude diagram in the region of the red clump of the cluster. Two of these stars are surely identified as red clump stars for the first time. For those five stars, we provide chemical abundances of 31 elements. The mean radial velocity of NGC 6811 is found to be +6.68 ± 0.08 km s-1 and the mean metallicity and overall abundance pattern are shown to be very close to solar with an exception of Ba which we find to be overabundant.

Molenda-?akowicz, J.; Brogaard, K.; Niemczura, E.; Bergemann, M.; Frasca, A.; Arentoft, T.; Grundahl, F.

2014-12-01

107

Optical spectroscopic studies of two star forming regions  

NASA Astrophysics Data System (ADS)

The Rho Ophiuchi and Serpens molecular clouds are sites of low mass star formation. The goals of this study were to identify young stellar objects (YSOs) and estimate ages and masses in order to infer an initial mass function (IMF), investigate disk evolution, and determine the star-forming history. Optical spectroscopic surveys of an unbiased sample of candidate young stars have been completed. Optical images taken in different photometric bands were used to create color-magnitude diagrams from which sources were selected for spectroscopic observation. In combination with published data, 135 association members in Rho Ophiuchi and 63 association members plus 16 possible members in Serpens have been identified based on the presence of H-alpha in emission, lithium absorption, X-ray emission, a mid-infrared excess, and/or reflection nebulosity. Effective temperatures and bolometric luminosities were compared with theoretical tracks and isochrones for pre-main-sequence stars to estimate ages and masses. Both regions have similar median ages, supporting the idea that star formation is a relatively fast process. In Rho Ophiuchi, no age spread was found. In Serpens, an age spread of 1-5 Myrs was found; it could not be determined if this age spread was intrinsic or a result of contamination from foreground young stars. Consistent with these ages similar circumstellar disk frequencies were found. In Rho Ophiuchi, an IMF consistent with the field star IMF for YSOs with masses > 0.2 Msun was inferred. In Serpens, the IMF was in agreement with the field star IMF for M > Msun. Previous studies of these regions have been biased towards particular stages in the star formation process. This study has provided an unbiased sample of pre-main sequence objects, necessary to obtain a complete picture of star formation.

Erickson, Kristen Leilani

108

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

109

DFT study of conformational and spectroscopic properties of yatakemycin.  

PubMed

Molecular structure and conformational preferences of yatakemycin, a novel and exceptionally potent antitumor agent, have been investigated using the density functional theory (DFT) formalism. From the relative stability of various possible conformations, it is found that two conformers are nearly isoenergetic and markedly more stable than the others in the gas phase. To test the effect of polar mediums, the relative energies have been recalculated using the self-consistent reaction field method. Thus, the most stable conformer of the isolated molecule in the gas phase is expected to be still more preferred in solution. The molecular structure of yatakemycin has also been studied by means of its spectroscopic properties. The DFT results satisfactorily reproduce the experimental data and corroborate the reliability of the structural characterization advanced for yatakemycin. The lowest-energy electronic transitions have been interpreted with time-dependent DFT calculations. Notably, the strong IR band observed at 2852 cm(-1) is unambiguously assigned to the O-H stretching of the (C7)O-H...O(C12) fragment, linked by a strong intramolecular H-bond, and may be viewed as a distinctive fingerprint of yatakemycin. Furthermore, the calculated set of NMR chemical shifts of carbonyl carbon atoms and indole protons, the most sensitive to stereoelectronic factors, is consistent with experiment. The effects of both protonation and oxidation on the geometry of the most stable conformer have also been studied. With reference to yatakemycin's DNA alkylation properties, the structure of the yatakemycin-adenine adduct has been theoretically modeled and found to be consistent with experimental spectroscopic evidence. PMID:17564422

Pichierri, Fabio; Galasso, Vinicio

2007-07-01

110

Spectroscopic, electronic structure and natural bond analysis of 2-aminopyrimidine and 4-aminopyrazolo[3,4-d]pyrimidine: A comparative study  

NASA Astrophysics Data System (ADS)

The FTIR and FT-Raman spectra of 2-aminopyrimidine (2-AP) and 4-aminopyrazolo[3,4-d]pyrimidine (4-APP) has been recorded in the region 4000-400 and 3500-100 cm-1, respectively. The tautomeric stability, optimized geometry, frequency and intensity of the vibrational bands of 2-AP and 4-APP were obtained by the DFT level using 6-31G(d) and 6-31G(d,p) basis sets. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. A detailed interpretation of the infrared and Raman spectra of 2-AP and 4-APP are also reported based on total energy distribution (TED). The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically simulated spectra. The 1H and 13C NMR spectra have been simulated using the gauge independent atomic orbital (GIAO) method. The theoretical UV-Vis spectrum of the compound using CIS method and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The first order hyperpolarizability (?0) of these novel molecular system and related properties (?, ?0 and ??) of 2-AP and 4-APP are calculated using DFT/6-31G(d) method on the finite-field approach. The Mulliken charges, the values of electric dipole moment (?) of the molecule were computed using DFT calculations. The change in electron density (ED) in the ?? antibonding orbitals and stabilization energies E(2) have been calculated by natural bond (NBO) analysis to give clear evidence of stabilization originating in the hyper conjugation of hydrogen-bonded interactions.

Prabavathi, N.; Nilufer, A.; Krishnakumar, V.; Akilandeswari, L.

2012-10-01

111

Spectroscopic, electronic structure and natural bond analysis of 2-aminopyrimidine and 4-aminopyrazolo[3,4-d]pyrimidine: a comparative study.  

PubMed

The FTIR and FT-Raman spectra of 2-aminopyrimidine (2-AP) and 4-aminopyrazolo[3,4-d]pyrimidine (4-APP) has been recorded in the region 4000-400 and 3500-100 cm(-1), respectively. The tautomeric stability, optimized geometry, frequency and intensity of the vibrational bands of 2-AP and 4-APP were obtained by the DFT level using 6-31G(d) and 6-31G(d,p) basis sets. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. A detailed interpretation of the infrared and Raman spectra of 2-AP and 4-APP are also reported based on total energy distribution (TED). The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically simulated spectra. The (1)H and (13)C NMR spectra have been simulated using the gauge independent atomic orbital (GIAO) method. The theoretical UV-Vis spectrum of the compound using CIS method and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The first order hyperpolarizability (?(0)) of these novel molecular system and related properties (?, ?(0) and ??) of 2-AP and 4-APP are calculated using DFT/6-31G(d) method on the finite-field approach. The Mulliken charges, the values of electric dipole moment (?) of the molecule were computed using DFT calculations. The change in electron density (ED) in the ?(?) antibonding orbitals and stabilization energies E(2) have been calculated by natural bond (NBO) analysis to give clear evidence of stabilization originating in the hyper conjugation of hydrogen-bonded interactions. PMID:22683558

Prabavathi, N; Nilufer, A; Krishnakumar, V; Akilandeswari, L

2012-10-01

112

Diagnostic Chemical Analysis of Exhaled Human Breath Using a Novel Sub-Millimeter Spectroscopic Approach  

NASA Astrophysics Data System (ADS)

As many as 3000 chemicals are reported to be found in exhaled human breath. Many of these chemicals are linked to certain health conditions and environmental exposures. Present state of the art techniques used for analysis of exhaled human breath include mass spectrometry based methods, infrared spectroscopic sensors, electro chemical sensors and semiconductor oxide based testers. Some of these techniques are commercially available but are somewhat limited in their specificity and exhibit fairly high probability of false alarm. Here, we present the results of our most recent study which demonstrated a novel application of a terahertz high resolutions spectroscopic technique to the analysis of exhaled human breath, focused on detection of ethanol in the exhaled breath of a person which consumed an alcoholic drink. This technique possesses nearly ``absolute'' specificity and we demonstrated its ability to uniquely identify ethanol, methanol, and acetone in human breath. This project is now complete and we are looking to extend this method of chemical analysis of exhaled human breath to a broader range of chemicals in an attempt to demonstrate its potential for biomedical diagnostic purposes.

Fosnight, Alyssa M.; Moran, Benjamin L.; Branco, Daniela R.; Thomas, Jessica R.; Medvedev, Ivan R.

2013-06-01

113

Studies of Two Massive Eclipsing Double-lined Spectroscopic Binaries  

NASA Astrophysics Data System (ADS)

As part of an ongoing investigation into the spectroscopic variability of massive stars, we present preliminary results for two double-lined eclipsing binary systems, HD 130146 (VZ Cen) and LS 3052 (V 1176 Cen). In our analysis we used archival Hipparcos photometry for HD 103146 and All Sky Automated Survey V-band photometry for LS 3052. All spectra were obtained from the Cerro Tololo Inter-American Observatory 1.5-m telescope. The systems were analyzed using the Eclipsing Light Curve code (ELC; Orosz & Hauschildt 2000). A combined analysis of these data yields masses, radii, effective temperatures, gravities, and estimates for the ages and distances of each system. HD 103146 is a 4.9 day binary with a slightly evolved primary (T_{eff} 28000 K and log g 3.75) while the secondary nearly fills its Roche lobe. LS 3052 has an eccentric orbit with a period of 31 days and contains both an evolved primary and secondary. Preliminary solutions indicate the primary's mass to be 33 Mo with a 21 Mo secondary.

Williams, Stephen J.; Gies, D. R.; Hillwig, T. C.; McSwain, M. V.; Huang, W.

2013-06-01

114

Whole-Brain Analysis of Amyotrophic Lateral Sclerosis by Using Echo-Planar Spectroscopic Imaging  

PubMed Central

Purpose: To detect regional metabolic differences in amyotrophic lateral sclerosis (ALS) with whole-brain echo-planar spectroscopic imaging. Materials and Methods: Sixteen patients with ALS (nine men, seven women; mean age, 56.6 years), five persons suspected of having ALS (four men, one woman; mean age, 62.6 years), and 10 healthy control subjects (five men, five women; mean age, 56.1 years) underwent echo-planar spectroscopic imaging after providing informed consent. The study was approved by the institutional review board and complied with HIPAA. Data were analyzed with the Metabolic Imaging and Data Analysis System software, and processed metabolite maps were coregistered and normalized to a standard brain template. Metabolite maps of creatine (Cr), choline (Cho), and N-acetylaspartate (NAA) were segmented into 81 regions with Automated Anatomical Labeling software to measure metabolic changes throughout the brains of patients with ALS. Statistical analysis involved an unpaired, uncorrected, two-sided Student t test. Results: The NAA/Cho ratio across six regions was significantly lower by a mean of 23% (P ? .01) in patients with ALS than in control subjects. These regions included the caudate, lingual gyrus, supramarginal gyrus, and right and left superior and right inferior occipital lobes. The NAA/Cr ratio was significantly lower (P ? .01) in eight regions in the patient group, by a mean of 16%. These included the caudate, cuneus, frontal inferior operculum, Heschl gyrus, precentral gyrus, rolandic operculum, and superior and inferior occipital lobes. The Cho/Cr ratio did not significantly differ in any region between patient and control groups. Conclusion: Whole-brain echo-planar spectroscopic imaging permits detection of regional metabolic abnormalities in ALS, including not only the motor cortex but also several other regions implicated in ALS pathophysiologic findings. © RSNA, 2013 PMID:23360740

Verma, Gaurav; Woo, John H.; Chawla, Sanjeev; Wang, Sumei; Sheriff, Sulaiman; Elman, Lauren B.; McCluskey, Leo F.; Grossman, Murray; Melhem, Elias R.; Maudsley, Andrew A.

2013-01-01

115

Experimental and Theoretical Spectroscopic Study of 3-Aryl-2-Phenyl-3-Phenylaminopropanoic Acids  

NASA Astrophysics Data System (ADS)

A series of 3-aryl-2-phenyl-3-phenylaminopropanoic acids is synthesized, isolated, and spectroscopically and structurally elucidated. The effect of the substituents on the spectroscopic characteristics and conformations has been studied using IR, UV, and 1H NMR spectroscopy. Theoretical quantum chemical calculations are performed with a view to explaining and supporting the experimental optical properties and electronic structure of the compounds studied.

Tasheva, D. N.; Zareva, S. Y.

2014-09-01

116

Spectroscopic database  

NASA Technical Reports Server (NTRS)

Several aspects of quantitative atmospheric spectroscopy are considered, using a classification of the molecules according to the gas amounts in the stratosphere and upper troposphere, and reviews of quantitative atmospheric high-resolution spectroscopic measurements and field measurements systems are given. Laboratory spectroscopy and spectral analysis and prediction are presented with a summary of current laboratory spectroscopy capabilities. Spectroscopic data requirements for accurate derivation of atmospheric composition are discussed, where examples are given for space-based remote sensing experiments of the atmosphere: the ATMOS (Atmospheric Trace Molecule) and UARS (Upper Atmosphere Research Satellite) experiment. A review of the basic parameters involved in the data compilations; a summary of information on line parameter compilations already in existence; and a summary of current laboratory spectroscopy studies are used to assess the data base.

Husson, N.; Barbe, A.; Brown, L. R.; Carli, B.; Goldman, A.; Pickett, H. M.; Roche, A. E.; Rothman, L. S.; Smith, M. A. H.

1985-01-01

117

A photometric and spectroscopic study of BG Canis Minoris.  

NASA Astrophysics Data System (ADS)

The photometric and spectroscopic analysis presented here has revealed new observational features in the Intermediate Polar BG CMi. We have found a strong variability of the dominant light pulsations, rotational (913s) and orbital (3.23hr), on a timescale of years. Variations in the amplitude of the spin pulsation with epoch generally appear to be anti-correlated with that of the orbital modulation with the former decreasing while the latter increases. We do not find stable periodic signals at other frequencies as well as no indication of periodicity at the 847s X-ray period. UV and optical orbital continuum modulations reveal two components at different temperatures. The hot contribution is identified with the bulge (the heated face of the hot-spot) and the cool one with the hot-spot itself eclipsed by the secondary star. Orbital phase resolved spectroscopy reveals a rotational disturbance in the HeII emission line, indicating a partial eclipse of circulating material around the white dwarf, possibly in the form of a ring. From the orbital motion of the white dwarf, we also infer that BG CMi is a moderate inclination system (i~55^o^-75^o^).

de Martino, D.; Mouchet, M.; Bonnet-Bidaud, J. M.; Vio, R.; Rosen, S. R.; Mukai, K.; Augusteijn, T.; Garlick, M. A.

1995-06-01

118

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

SciTech Connect

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

Jagadeesha, N. [Department of Physics, Govt. College (Autonomous), Mondya 57140 (India); Gowda, V. C. Veeranna [Department of Physics, Govt. College for Woman, Chintamani 563125 (India); Chakradhar, R. P. S. [Scientist, Surface Engineering Division, National Aerospace Laboratories, Bangalore 560017 (India); Reddy, C. Narayana [Department of Physics, Maharani's Science College for woman (PG Centre, Bangalore University), Bangalore 560001 (India)

2011-07-15

119

Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite minerals  

E-print Network

Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite] Phyllosilicates on Mars mapped by infrared spectroscopic techniques could have been affected by dehydration and with meteor impact. The effects of heatinduced dehydration and/or dehydroxylation on the infrared spectra

Glotch, Timothy D.

120

Study of the spray to globular transition in gas metal arc welding: a spectroscopic investigation  

E-print Network

Study of the spray to globular transition in gas metal arc welding: a spectroscopic investigation of the spray to globular transition in gas metal arc welding: a spectroscopic investigation F Valensi1.iop.org/JPhysD/46/224005 Abstract The gas metal arc welding (GMAW) process is strongly influenced by the composition

121

Spectroscopic and DFT study of 3-quinolyl-?-aminophosphonates  

NASA Astrophysics Data System (ADS)

Spectroscopic and DFT study of two types of 3-quinolyl-?-aminophosphonate derivatives obtained by one-pot microwave-assisted synthesis of quinoline-3-carboxaldehyde and aniline as well as 3-aminoquinoline and benzaldehyde, respectively, with diethyl phosphite, have been described. Besides the diethyl [?-anilino- N-(3-quinolylmethyl)]phosphonate ( 1) and diethyl [?-(3-quinolylamino)- N-benzyl]phosphonate ( 4) as the main reaction products, in both cases some unexpected monoester phosphonate derivatives were obtained as the by-products. In the first case along with diester 1, its corresponding monoethyl ester ( 2) and one monoethyl dihydrophosphonate-phosphate derivative ( 3) were formed, while in the second case diester 4 and a hydrogen phosphonamidate ( 5) were isolated. All quinoline-based ?-aminophosphonates ( 1- 5) have been characterized by IR spectroscopy, and the results obtained are compared and discussed with those obtained by the NMR studies. Combining experimental IR, 1H and 13C NMR spectra with DFT calculations, most intensive IR spectral bands of diesters 1 and 4, along with 1H and 13C NMR resonances of 1, 2 and 4 derivatives, were assigned.

Juribaši?, Marina; Tušek-Boži?, Ljerka

2009-04-01

122

A Far Ultraviolet Spectroscopic Analysis of the Hot Components in Six S-Type Symbiotic Variables  

NASA Astrophysics Data System (ADS)

We have carried out a far ultraviolet spectroscopic analysis of archival IUE and HST spectra of six symbiotic variables. Two systems, LT Del, which has had one recorded outburst, and BD-21 3873 (= IV Vir) which has had no recorded outburst, are yellow symbiotic systems. Two systems, V443 Her and RW Hya, have also never had a recorded outburst. Two other symbiotics, StH?190 and CQ Dra, are more strongly interacting with an outburst history. We have studied these systems during their quiescence in order to shed light on the nature of their hot components by fitting the observations with optically thick accretion disk models and model white dwarf photospheres. We present the results from our synthetic spectral analysis. This research was supported by NASA grant NNX13AF12G

Kolobow, Craig; Sion, E. M.; Godon, P.; Sabra, B.; Mikolajewska, J.

2014-01-01

123

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

124

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

125

The oEA star TW Dra - a spectroscopic analysis  

NASA Astrophysics Data System (ADS)

We investigate a spectroscopic time series of the oscillating Algol-type star TW Dra to derive basic system and stellar parameters and to prepare for mode identification. From the orbital solution we derive precise masses and get disentangled spectra of the components by using KOREL. For the primary we derive about solar abundance. Computed LSD profiles show a puzzling picture of blue-to-red traveling bumps indicating a rich spectrum of nonradial pulsations. Three pulsation frequencies could be found by using FAMIAS. A first attempt of mode identification indicates that TW Dra shows high-degree modes in the range of l=7-12.

Lehmann, H.; Tkachenko, A.; Tsymbal, V.; Mkrtichian, D. E.

2008-12-01

126

Moessbauer spectroscopic studies of hemoglobin and its isolated subunits  

SciTech Connect

Samples of 90% enriched 57Fe hemoglobin and its isolated subunits have been prepared. Moessbauer spectroscopic measurements have been made on three such samples. Sample one contained contributions of oxyhemoglobin, deoxyhemoglobin, and carbonmonoxyhemoglobin. This sample was studied from a temperature of 90 K down to 230 mK. Measurements were also made at 4.2 K using a small applied magnetic field of 1.0 T. In general, the measured quadrupole splittings and isomer shifts for each component agreed with previous measurements on single component samples in the literature, and thus demonstrated that chemically enriched hemoglobin has not been altered. The second and third samples were isolated alpha and beta subunits, respectively. We have found measurable Moessbauer spectral differences between the HbO/sub 2/ sites in the alpha subunit sample and the beta subunit sample. The measured Moessbauer spectral areas indicate that the iron ion has the largest mean-square displacement at the deoxy Hb sites as compared to that at the oxy- and carbonmonoxy Hb sites. The mean-square displacement at the HbO/sub 2/ sites is the smallest.

Hoy, G.R.; Cook, D.C.; Berger, R.L.; Friedman, F.K.

1986-05-01

127

Spectroscopic Study on the Beryllium Abundances of Red Giant Stars  

E-print Network

An extensive spectroscopic study was carried out for the beryllium abundances of 200 red giants (mostly of late G and early K type), which were determined from the near-UV Be II 3131.066 line based on high-dispersion spectra obtained by Subaru/HDS, with an aim of investigating the nature of surface Be contents in these evolved giants; e.g., dependence upon stellar parameters, degree of peculiarity along with its origin and build-up timing. We found that Be is considerably deficient (to widely different degree from star to star) in the photosphere of these evolved giants by ~1-3 dex (or more) compared to the initial abundance. While the resulting Be abundances (A(Be)) appear to weakly depend upon T_eff, log g, [Fe/H], M, age, and v_sin i, this may be attributed to the metallicity dependence of A(Be) coupled with the mutual correlation between these stellar parameters, since such tendencies almost disappear in the metallicity-scaled Be abundance ([Be/Fe]). By comparing the Be abundances (as well as their correl...

Takeda, Yoichi

2014-01-01

128

MULTI-OBJECTIVE SPECTROSCOPIC DATA ANALYSIS OF INERTIAL CONFINEMENT FUSION IMPLOSION CORES  

E-print Network

MULTI-OBJECTIVE SPECTROSCOPIC DATA ANALYSIS OF INERTIAL CONFINEMENT FUSION IMPLOSION CORES: PLASMA-ray images and X-ray line spectra. The method performs a search in multi-dimensional parameter space confinement fusion implosion cores based on the self-consistent analysis of simultaneous narrow-band X

Louis, Sushil J.

129

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

130

Effect of temperature on the methotrexate BSA interaction: Spectroscopic study  

NASA Astrophysics Data System (ADS)

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

Su?kowska, A.; Maci??ek, M.; Równicka, J.; Bojko, B.; Pentak, D.; Su?kowski, W. W.

2007-05-01

131

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

132

Spectroscopic Analysis of Impurity Precipitates in CdS Films  

SciTech Connect

Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Devices incorporating chemical-bath-deposited (CBD) CdS are comparable in quality to devices incorporating purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this paper, we summarize and review the results of Fourier transform infrared (FTIR), Auger, electron microprobe, and X-ray photoelectron spectroscopic (XPS) analyses of the impurities in CBD CdS films. We show that these impurities differ as a function of substrate type and film deposition conditions. We also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

Webb, J. D.; Keane, J.; Ribelin, R.; Gedvilas, L.; Swartzlander, A.; Ramanathan, K.; Albin, D. S.; Noufi, R.

1999-10-31

133

Spectroscopic analysis of impurity precipitates in CdS films  

SciTech Connect

Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Devices incorporating chemical-bath-deposited (CBD) CdS are comparable in quality to devices incorporating purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this paper, we summarize and review the results of Fourier transform infrared (FTIR). Auger, electron microprobe, and X-ray photoelectron spectroscopic (XPS) analyses of the impurities in CBD CdS films. We show that these impurities differ as a function of substrate type and film deposition conditions. We also show that some of these impurities exist as 10{sup 2} micron-scale precipitates. {copyright} {ital 1999 American Institute of Physics.}

Webb, J.D.; Keane, J.; Ribelin, R.; Gedvilas, L.; Swartzlander, A.; Ramanathan, K.; Albin, D.S.; Noufi, R. [National Renewable Energy Laboratory (NREL), Golden, Colorado 80401-3393 (United States)

1999-03-01

134

Spectroscopic study on the beryllium abundances of red giant stars*  

NASA Astrophysics Data System (ADS)

An extensive spectroscopic study was carried out for the beryllium abundances of 200 red giants (mostly of late G- and early K-type), which were determined from the near-UV Be II 3131.066 line based on high-dispersion spectra obtained by Subaru/High Dispersion Spectrograph, with an aim of investigating the nature of surface Be contents in these evolved giants; e.g., dependence upon stellar parameters, degree of peculiarity along with its origin and build-up timing. We found that Be is considerably deficient (to widely different degrees from star to star) in the photosphere of these evolved giants by ˜ 1-3 dex (or more) compared to the initial abundance. While the resulting Be abundances [A(Be)] appear to depend weakly upon Teff, log g, [Fe/H], M, age, and ve sin i, this may be attributed to the metallicity dependence of A(Be) coupled with the mutual correlation between these stellar parameters, since such tendencies almost disappear in the metallicity-scaled Be abundance ([Be/Fe]). By comparing the Be abundances (as well as their correlations with Li and C) to the recent theoretical predictions based on sophisticated stellar evolution calculations, we concluded that such a considerable extent/diversity of Be deficit is difficult to explain only by the standard theory of first dredge-up in the envelope of red giants, and that some extra mixing process (such as rotational or thermohaline mixing) must be responsible, which presumably starts to operate already in the main-sequence phase. This view is supported by the fact that appreciable Be depletion is seen in less evolved intermediate-mass B-A type stars near to the main sequence.

Takeda, Yoichi; Tajitsu, Akito

2014-09-01

135

Spectroscopic study on the beryllium abundances of red giant stars*  

NASA Astrophysics Data System (ADS)

An extensive spectroscopic study was carried out for the beryllium abundances of 200 red giants (mostly of late G- and early K-type), which were determined from the near-UV Be II 3131.066 line based on high-dispersion spectra obtained by Subaru/High Dispersion Spectrograph, with an aim of investigating the nature of surface Be contents in these evolved giants; e.g., dependence upon stellar parameters, degree of peculiarity along with its origin and build-up timing. We found that Be is considerably deficient (to widely different degrees from star to star) in the photosphere of these evolved giants by ˜ 1-3 dex (or more) compared to the initial abundance. While the resulting Be abundances [A(Be)] appear to depend weakly upon Teff, log g, [Fe/H], M, age, and ve sin i, this may be attributed to the metallicity dependence of A(Be) coupled with the mutual correlation between these stellar parameters, since such tendencies almost disappear in the metallicity-scaled Be abundance ([Be/Fe]). By comparing the Be abundances (as well as their correlations with Li and C) to the recent theoretical predictions based on sophisticated stellar evolution calculations, we concluded that such a considerable extent/diversity of Be deficit is difficult to explain only by the standard theory of first dredge-up in the envelope of red giants, and that some extra mixing process (such as rotational or thermohaline mixing) must be responsible, which presumably starts to operate already in the main-sequence phase. This view is supported by the fact that appreciable Be depletion is seen in less evolved intermediate-mass B-A type stars near to the main sequence.

Takeda, Yoichi; Tajitsu, Akito

2014-10-01

136

FT-Raman spectroscopic analysis of pigments from an Augustinian friary.  

PubMed

The Raman spectroscopic analysis of several stone samples with applied red pigments obtained from an archaeological excavation of an Augustinian friary discovered during the construction of an extension to Hull Magistrates Court in 1994 has revealed a surprising diversity of composition. Cinnabar, red lead and haematite have all been identified alone or in admixture; the cinnabar is exceptional in that it has only been found heavily adulterated with red ochre and red lead, as the other two pigments are found alone. There are signatures of limewash putty, which has been applied to the stone substrate prior to the painting, which is characteristic of the Roman method of wall painting, and there are no traces of gypsum found in the specimens studied. This evidence indicates an early mediaeval method of stone decoration. PMID:20225060

Edwards, Howell G M; Newton, Emma M; O'Connor, Sonia; Evans, D

2010-08-01

137

Spectroscopic investigation and natural bond orbital analysis on 4-ethylmorpholine  

NASA Astrophysics Data System (ADS)

This study is an analysis of FT-IR (4000-400 cm-1) and FT-Raman (4000-0 cm-1) spectra of 4-ethylmorpholine (4EM). The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges have been calculated by using ab initio HF and density functional theory calculation (B3LYP) with 6-311+G(d,p) basis set. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FT-IR and FT-Raman spectra for 4EM. NBO analysis has been performed on the before and after flipping the chair conformation of 4EM at DFT method. The formation of the hydrogen bond was investigated using NBO calculations. The dipole moment (?) and polarizability (?), anisotropy polarizability (??) and hyperpolarizability (?) of the molecule have been reported. The theoretical UV-Visible spectrum of the compound was computed in the region 200-400 nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures were calculated.

Mahalakshmi, G.; Balachandran, V.

2014-04-01

138

POLARIZED RAMAN SPECTROSCOPIC STUDY OF THE PRESSURE-INDUCED PHASE CHANGE FROM  

E-print Network

1747P POLARIZED RAMAN SPECTROSCOPIC STUDY OF THE PRESSURE-INDUCED PHASE CHANGE FROM C2/C TO P21/C will be reported. Polarized spectra of an oriented crystal will be presented demonstrating the ability to obtain

Downs, Robert T.

139

Spectroscopic Study of Extracellular Polymeric Substances from Bacillus subtilis: Aqueous Chemistry and Adsorption  

E-print Network

Spectroscopic Study of Extracellular Polymeric Substances from Bacillus subtilis: Aqueous Chemistry March 3, 2004 Reactions at ionizable functional groups in extracellular polymeric substances (EPS) from lipopolysaccharides, teichoic acids and extra- cellular polymeric substances.6-9 Mineral surfaces exhibit positive

Chorover, Jon

140

A Broadband Viscoelastic Spectroscopic Study of Bovine Bone: Implications for Fluid Flow  

E-print Network

A Broadband Viscoelastic Spectroscopic Study of Bovine Bone: Implications for Fluid Flow P. M Center, University of Wisconsin-Madison, 147 Engineering Research Building, 1500 Engineering Drive transduction mechanisms in bone adaptation, a complementary experimental and analytical modeling effort has

Lakes, Roderic

141

Spectroscopic studies of uranium species for environmental decontamination applications  

NASA Astrophysics Data System (ADS)

After the Cold War, Department of Energy began to concentrate its efforts on cleanup of former nuclear material processing facilities, especially uranium-contaminated groundwater and soil. This research aims to study uranium association to both organic and inorganic compounds found in the contaminated environment in the hopes that the information gathered can be applied to the development and optimization of cost-effective remediation techniques. Spectroscopic and electrochemical methods will be employed to examine the behavior of uranium in given conditions to further our understanding of its impact on the environment. Uranium found in groundwater and soil bind with various ligands, especially organic ligands present in the environment due to natural sources (e.g. metabolic by-products or degradation of plants and animals) or man-made sources (e.g. chelating agents used in operating or cleanup of uranium processing facilities). We selected reasonable analogs of naturally occurring matter and studied their structure, chemical and electrochemical behavior and found that the structure of uranyl complexes depends heavily on the nature of the ligand and environmental factors such as pH. Association of uranium-organic complexes with anaerobic bacteria, Clostridium sp. was studied to establish if the bacteria can effectively bioreduce uranium while going through normal bacterial activity. It was found that the nature of the organic ligand affected the bioavailability and toxicity of the uranium on the bacteria. In addition, we have found that the type of iron corrosion products and uranyl species present on the surface of corroded steel depended on various environmental factors, which subsequently affected the removal rate of uranium by a citric acid/hydrogen peroxide/deionized water cleaning process. The method was found to remove uranium from only the topmost corrosion layers and residual uranium could be found (a) deeper in the corrosion layers where it is occluded by the steel corrosion products or (b) in areas where the dissolved uranium/iron species, the products generated by the dissolution power of citric acid, was not properly rinsed away.

Eng, Charlotte

142

Water pair potential of near spectroscopic accuracy. I. Analysis of potential surface and virial coefficients  

E-print Network

Water pair potential of near spectroscopic accuracy. I. Analysis of potential surface and virial pair potential for water was generated by fitting 2510 interaction energies computed by the use with experiment. Features of the water dimer potential energy surface have been analyzed using SAPT-5s. Average

143

Spectroscopic Studies of the Several Isomers of UO3  

SciTech Connect

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

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

2013-09-26

144

Structural, spectroscopic and theoretical study of novel ephedrinum salt  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

145

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

SciTech Connect

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. [Advanced Material Research Laboratory Department of Pure and Applied physics Guru Ghasidas Vishwavidyalaya, Bilaspur (C.G.)-495009 (India)

2011-11-22

146

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

NASA Astrophysics Data System (ADS)

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

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

147

Spectroscopic and structural studies of strongly correlated oxides  

NASA Astrophysics Data System (ADS)

This dissertation has involved the study of the electronic and crystal structures of strongly correlated oxides by means of a unique combination of several soft x-ray spectroscopies that are currently available at third generation synchrotron facilities. As the major topic, we present temperature-dependent data obtained from single crystals of colossal magnetoresistive manganites of composition La 1-xSrxMnO3 (LSMO, x = 0.3--0.4) using core and valence level photoemission, near edge x-ray absorption, x-ray emission, resonant inelastic x-ray scattering, and x-ray extended fine structure spectroscopies. A dramatic and reversible change of the electronic structure is observed on crossing the Curie temperature, including a significant increase of the local Mn spin moment by about one Bohr magneton and corresponding charge transfer/localization to the manganese atom, while the EXAFS data show signatures typical of Jahn-Teller distortions (JTDs). The charge localization onto the Mn atom concomitant with local JTDs at high temperature provides strong evidence for a direct detection of lattice polaron formation that could possibly lead also to ferromagnetic clusters in the metallic paramagnetic state. These results thus challenge the long-standing belief of some authors that the LSMO compounds are canonical double-exchange (DE) systems, described by the DE model alone and without the need to be supplemented by other more complex mechanism such as polaron formation and phase separation. Our results suggest that the presence of polarons above the Curie temperature, as well as microscopic tendencies toward phase separation, are general defining characteristics of all of the CMR materials, thus bringing unity to their theoretical description. We also present experimental and theoretical results related to multi-atom resonant photoemission (MARPE), a newly discovered spectroscopic effect in which the photoelectron intensity from a core level on one atom is influenced by a core-level absorption resonance on another. The variation of the observed MARPE intensity profiles as a function of both photon energy and x-ray incidence angle for the NiO (001) system, which exhibits a resonance between O1 s photoemission and the Ni 2p1/2,3/2 absorption resonances, are found to be well described by a macroscopic x-ray optical model (to which we will refer as a resonant x-ray optical (RXRO) approach) whose input is the complex dielectric constant on passing the relevant resonance. (Abstract shortened by UMI.)

Mannella, Norman

2003-07-01

148

Transport and spectroscopic studies of liquid and polymer electrolytes  

NASA Astrophysics Data System (ADS)

Liquid and polymer electrolytes are interesting and important materials to study as they are used in Li rechargeable batteries and other electrochemical devices. It is essential to investigate the fundamental properties of electrolytes such as ionic conductivity, diffusion, and ionic association to enhance battery performance in different battery markets. This dissertation mainly focuses on the temperature-dependent charge and mass transport processes and ionic association of different electrolyte systems. Impedance spectroscopy and pulsed field gradient nuclear magnetic resonance spectroscopy were used to measure the ionic conductivity and diffusion coefficients of ketone and acetate based liquid electrolytes. In this study, charge and mass transport in non-aqueous liquid electrolytes have been viewed from an entirely different perspective by introducing the compensated Arrhenius formalism. Here, the conductivity and diffusion coefficient are written as an Arrhenius-like expression with a temperature-dependent static dielectric constant dependence in the exponential prefactor. The compensated Arrhenius formalism reported in this dissertation very accurately describes temperature-dependent conductivity data for acetate and ketone-based electrolytes as well as temperature-dependent diffusion data of pure solvents. We found that calculated average activation energies of ketone-based electrolytes are close to each other for both conductivity and diffusion data (in the range 24-26 kJ/mol). Also, this study shows that average activation energies of acetate-based electrolytes are higher than those for the ketone systems (in the range 33-37 kJ/mol). Further, we observed higher dielectric constants and ionic conductivities for both dilute and concentrated ketone solutions with temperature. Vibrational spectroscopy (Infrared and Raman) was used to probe intermolecular interactions in both polymer and liquid electrolytes, particularly those which contain lithium trifluoromethanesulfonate, LiCF3SO3, abbreviated here as lithium triflate(LiTf). The molar absorption coefficients of nus(SO3), deltas(CF3), and deltas(SO3) vibrational modes of triflate anion in the LiTf-2-pentanone system were found to be 6708+/-89, 5182+/-62, and 189+/-2 kg mol-1 cm-1, respectively using Beer-Lambert law. Our results show that there is strong absorption by nu s(SO3) mode and weak absorption by deltas(CF 3) mode. Also, the absorptivity of each mode is independent of the ionic association with Li ions. This work allows for the direct quantitative comparison of calculated concentrations in different samples and different experimental conditions. In addition, this dissertation reports the temperature-dependent vibrational spectroscopic studies of pure poly(ethylene oxide) and LiTf-poly(ethylene oxide) complexes. A significant portion of this dissertation focuses on crystallographic studies of ketone-salt (LiTf:2-pentanone and NaTf:2-hexanone) and amine-acid (diethyleneamine: H3PO4, N,N'-dimethylethylenediamine:H 3PO4, and piperazine:H3PO4) systems. Here, sodium trifluoromethanesulfonate, NaCF3SO3 is abbreviated as NaTf. As model compounds, these systems provide valuable information about ion-ion interactions, which are helpful for understanding complex polymer systems. During this study, five crystal structures were solved using single X-ray diffractometry, and their vibrational modes were studied in the mid-infrared region. In the secondary amine/phosphoric acid systems, the nature of hydrogen-bonding network was examined.

Bopege, Dharshani Nimali

149

Raman spectroscopic analysis of atypical proliferative lesions of the breast  

NASA Astrophysics Data System (ADS)

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 be made. At present there is no clear recognition of the biochemical changes that distinguish between the different proliferative lesions of the breast. Our aim is to understand these changes through Raman mapping studies. Raman spectroscopy is a highly sensitive and specific technique for demonstration of biochemical changes in different atypical proliferative lesions of the breast. The technique could be used to classify the different grades and analyse progression of pathology in the proliferative lesions of the breast. Breast pathologists carefully marked 50 ducts and classified the different pathology on H and E sections from biopsy samples. Raman spectra were measured, using a Renishaw Raman Spectrometer, on a 20-micron thick consecutive frozen section. Principal component analysis was undertaken using Matlab. Pseudocolor maps of the principal components scores have been generated. The peaks of the corresponding loads were identified enabling visualisation of the biochemical changes associated with proliferative lesions. Proliferative lesions of the duct were grouped according to the existing standard pathological classification and formed four major groups-HUT, ADH, DCIS and IDC. Spectra of biochemical constituents were fitted to mean spectra from selected regions, taken from maps of each pathology, to identify the relative concentration of the constituents. The study gave an insight into chemical make up of the ducts in each pathology group and showed similar results to earlier studies in progression but no clear-cut demarcation or continuum of the proliferative disease.

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

2006-02-01

150

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

151

The ARAUCARIA project: Grid-based quantitative spectroscopic study of massive blue stars in NGC 55  

NASA Astrophysics Data System (ADS)

Context. The quantitative study of the physical properties and chemical abundances of large samples of massive blue stars at different metallicities is a powerful tool to understand the nature and evolution of these objects. Their analysis beyond the Milky Way is challenging, nonetheless it is doable and the best way to investigate their behavior in different environments. Fulfilling this task in an objective way requires the implementation of automatic analysis techniques that can perform the analyses systematically, minimizing at the same time any possible bias. Aims: As part of the ARAUCARIA project we carry out the first quantitative spectroscopic analysis of a sample of 12 B-type supergiants in the galaxy NGC 55 at 1.94 Mpc away. By applying the methodology developed in this work, we derive their stellar parameters, chemical abundances and provide a characterization of the present-day metallicity of their host galaxy. Methods: Based on the characteristics of the stellar atmosphere/line formation code fastwind, we designed and created a grid of models for the analysis of massive blue supergiant stars. Along with this new grid, we implemented a spectral analysis algorithm. Both tools were specially developed to perform fully consistent quantitative spectroscopic analyses of low spectral resolution of B-type supergiants in a fast and objective way. Results: We present the main characteristics of our fastwind model grid and perform a number of tests to investigate the reliability of our methodology. The automatic tool is applied afterward to a sample of 12 B-type supergiant stars in NGC 55, deriving the stellar parameters, Si , C , N , O and Mg abundances. The results indicate that our stars are part of a young population evolving towards a red supergiant phase. For half of the sample we find a remarkable agreement between spectroscopic and evolutionary masses, whilst for the rest larger discrepancies are present, but still within the uncertainties. The derived chemical composition hints to an average metallicity similar to the one of the Large Magellanic Cloud, with no indication of a spatial trend across the galaxy. Conclusions: The consistency between the observed spectra and our stellar models supports the reliability of our methodology. This objective and fast approach allows us to deal with large samples in an accurate and more statistical way. These are two key issues to achieve an unbiased characterization of the stars and their host galaxies. Based on observations obtained at the ESO VLT Large Programme 171.D-0004.

Castro, N.; Urbaneja, M. A.; Herrero, A.; Garcia, M.; Simón-Díaz, S.; Bresolin, F.; Pietrzy?ski, G.; Kudritzki, R.-P.; Gieren, W.

2012-06-01

152

The GEISA spectroscopic database: Current and future archive for Earth and planetary atmosphere studies  

Microsoft Academic Search

The development of Gestion et Etude des Informations Spectroscopiques Atmosphériques (GEISA: Management and Study of Spectroscopic Information) was started over three decades at Laboratoire de Météorologie Dynamique (LMD) in France. GEISA is a computer accessible spectroscopic database, designed to facilitate accurate forward radiative transfer calculations using a line-by-line and layer-by-layer approach. More than 350 users have been registered for on-line

N. Jacquinet-Husson; N. A. Scott; A. Chédin; L. Crépeau; R. Armante; V. Capelle; J. Orphal; A. Coustenis; C. Boonne; N. Poulet-Crovisier; A. Barbe; M. Birk; L. R. Brown; C. Camy-Peyret; C. Claveau; K. Chance; N. Christidis; C. Clerbaux; P. F. Coheur; V. Dana; L. Daumont; M. R. De Backer-Barilly; G. Di Lonardo; J. M. Flaud; A. Goldman; A. Hamdouni; M. Hess; M. D. Hurley; D. Jacquemart; I. Kleiner; P. Köpke; J. Y. Mandin; S. Massie; S. Mikhailenko; V. Nemtchinov; A. Nikitin; D. Newnham; A. Perrin; V. I. Perevalov; S. Pinnock; L. Régalia-Jarlot; C. P. Rinsland; A. Rublev; F. Schreier; L. Schult; K. M. Smith; S. A. Tashkun; J. L. Teffo; R. A. Toth; Vl. G. Tyuterev; J. Vander Auwera; P. Varanasi; G. Wagner

2008-01-01

153

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

154

Spectroscopic abundance analysis of dwarfs in young open cluster IC 4665  

E-print Network

We report a detailed spectroscopic abundance analysis for a sample of 18 F-K dwarfs of the young open cluster IC 4665. Stellar parameters and element abundances of Li, O, Mg, Si, Ca, Ti, Cr, Fe and Ni have been derived using the spectroscopic synthesis tool SME (Spectroscopy Made Easy). Within the measurement uncertainties the iron abundance is uniform with a standard deviation of 0.04 dex. No correlation is found between the iron abundance and the mass of the stellar convective zone, and between the Li abundance and the Fe abundance. In other words, our results do not reveal any signature of accretion and therefore do not support the scenario that stars with planets (SWPs) acquire their on the average higher metallicity compared to field stars via accretion of metal-rich planetary material. Instead the higher metallicity of SWPs may simply reflect the fact that planet formation is more efficient in high metallicity environs. However, since that many details of the planet system formation processes remain poorly understood, further studies are needed for a final settlement of the problem of the high metallicity of SWPs. The standard deviation of [Fe/H] deduced from our observations, taken as an upper limit on the metallicity dispersion amongst the IC 4665 member stars, has been used to constrain proto-planetary disk evolution, terrestrial and giant planets formation and evolution processes. Our results do not support the possibility that the migration of gas giants and the circularization of terrestrial planets' orbits are regulated by their interaction with a residual population of planetesimals and dust particles.

Z. -X. Shen; B. Jones; D. N. C. Lin; X. -W. Liu; S. -L. Li

2005-08-18

155

A Scalable Parallel Genetic Algorithm for Xray Spectroscopic Analysis  

E-print Network

to attack the problem of finding temperature and den­ sity gradients of ICF implosion cores through multi analysis of plasma gradients in inertial confinement fusion (ICF) implosion cores. In previous work, we had temperature and density of astro­ physical as well as laboratory plasmas [9]. Analysis based Permission

Louis, Sushil J.

156

Microwave spectra of some chlorine and fluorine compounds. [spectroscopic analysis  

NASA Technical Reports Server (NTRS)

A computer-controlled microwave spectrometer was used to catalog reference spectra for chemical analysis. Tables of absorption frequencies, peak absorption intensities, and integrated intensities are shown for 21 organic compounds which contain chlorine, fluorine, or both.

White, W. F.

1975-01-01

157

A General Chemistry Laboratory Theme: Spectroscopic Analysis of Aspirin  

NASA Astrophysics Data System (ADS)

In this paper, we describe the introduction of spectroscopy into the general chemistry laboratory using a series of experiments based on a common substance, aspirin. In the first lab the students synthesize and recrystallize aspirin and take melting points of their product, an aspirin standard, and salicylic acid. The students perform the remaining experiments on a rotating basis where the following four labs run simultaneously: structural characterization of the synthesized aspirin by IR and NMR; analysis of synthesized aspirin and commercial products by UV vis spectroscopy; analysis of synthesized aspirin and commercial products by HPLC; and analysis of calcium in commercial buffered aspirin tablets by AAS. In each of the analysis experiments, students collect, graph, and analyze their data using a spreadsheet. We have found that this series of labs has been very beneficial to our students. From the course evaluations, students indicate that they are beginning to understand how chemistry is applied outside of the classroom.

Byrd, Houston; O'Donnell, Stephen E.

2003-02-01

158

Spectroscopic studies on gallic acid and its azo derivatives and their iron(III) complexes.  

PubMed

Azo gallic derivatives and their iron(III) complexes were synthesized and characterized. The stereochemistry and the mode of bonding of the complexes were achieved based on elemental analysis, UV-Vis and IR. The thermal behaviors of the complexes were studied. The effect of pH on the electronic absorption spectra of gallic acid and its azo derivatives are discussed. Different spectroscopic methods (molar ratio, straight line method, continuous variation, slope ratio and successive method) are applied for determination of stoichiometry and pK values for the complex formation of gallic acid with iron(III) in aqueous media. Iron(III) complexes of gallic acid is formed with different ratio: 1:1, 1:2, 1:3 and 1:4 (M:L). PMID:24211811

Masoud, Mamdouh S; Ali, Alaa E; Haggag, Sawsan S; Nasr, Nessma M

2014-01-01

159

FTIR-ATR-spectroscopic analysis of Bis-Crown ether based PVC-membranes  

Microsoft Academic Search

To get more information on the phase boundary and bulk membrane processes, the short and long time behaviour of potassium selective solvent polymeric membranes was studied. In parallel with the measurement of the dynamic response of model membranes, in situ spectroscopic measurements applying the Attenuated Total Reflection (ATR) technique in the infrared region, were carried out in solutions containing anions

K. Tóth; E. Lindner; E. Pungor; E. Zippel; R. Kellner

1988-01-01

160

Preoperative Proton MR Spectroscopic Imaging of Brain Tumors: Correlation with Histopathologic Analysis of Resection Specimens  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Tumor progression is often difficult to distinguish from nonneoplastic treatment response on the basis of MR images alone. This study correlates me- tabolite levels measured by preoperative MR spectroscopic (MRS) imaging with histologic find- ings of biopsies, obtained during image-guided resections of brain mass lesions, to clarify the potential role of MRS in making this distinction. METHODS:

Chris Dowling; Andrew W. Bollen; Susan M. Noworolski; Michael W. McDermott; Nicholas M. Barbaro; Roland G. Henry; Susan M. Chang; William P. Dillon; Sarah J. Nelson; Daniel B. Vigneron

2001-01-01

161

Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration  

Microsoft Academic Search

Using scatterometry based on Spectroscopic Ellipsometry, a complete study of Gate lithography level measurement on standard products has been conducted. Experiments were done on typical ST batches for 120, 90, and 65 nm nodes. KLA-Tencor SpectraCD SE system is used to collect and analyze line critical dimensions and profiles. A systematic correlation with Scanning Electron Microscope (SEM) is done, completed

David Herisson; DaniEle Neira; Cyril Fernand; Philippe Thony; Daniel Henry; Stephanie Kremer; Marco Polli; Marco Guevremont; Assim Elazami

2003-01-01

162

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

PubMed

We have investigated the binding of the biologically important flavonoid fisetin with the carrier protein bovine serum albumin using multi-spectroscopic and molecular docking methods. The binding constants were found to be in the order of 10(4) M(-1) and the number of binding sites was determined as one. MALDI-TOF analyses showed that one fisetin molecule binds to a single bovine serum albumin (BSA) molecule which is also supported by fluorescence quenching studies. The negative Gibbs free energy change (?G°) values point to a spontaneous binding process which occurs through the presence of electrostatic forces with hydrophobic association that results in a positive entropy change (+51.69 ± 1.18 J mol(-1) K(-1)). The unfolding and refolding of BSA in urea have been studied in absence and presence of fisetin using steady-state fluorescence and lifetime measurements. Urea denaturation studies indicate that fisetin is gradually released from its binding site on the protein. In the absence of urea, an increase in temperature that causes denaturation of the protein results in the release of fisetin from its bound state indicating that fisetin binds only to the native state of the protein. The circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic studies showed an increase in % ?-helix content of BSA after binding with fisetin. Site marker displacement studies in accordance with the molecular docking results suggested that fisetin binds in close proximity of the hydrophobic cavity in site 1 (subdomain IIA) of the protein. The PEARLS (Program of Energetic Analysis of Receptor Ligand System) has been used to estimate the interaction energy of fisetin with BSA and the results are in good correlation with the experimental findings. PMID:23277393

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

2013-04-01

163

Analysis of FT-IR spectroscopic data: The Voigt profile  

NASA Astrophysics Data System (ADS)

A novel spectral analysis technique is presented for the determination of peak areas from spectra in which there are multiple overlapping peaks. The technique involves a combination of Fourier spectral analysis and profile modeling. Although the technique presented could be applied to many different types of problems (analysis of UV spectra or chromatographic results) it is applied here to the problem of determining, from Fourier transform infrared (FT-IR) spectra, the peak areas which correspond to monomeric and hydrogen-bonded species. For FT-IR spectra it is found that the Voigt profile is better than either the Lorentzian or Gaussian profiles. Use of the Voigt profile leads to more accurate and descriptive spectral peak parameters and, in turn, to more accurate determinations of concentrations of monomeric and hydrogen-bonded species. The technique is demonstrated using the carbonyl peaks (monomeric and hydrogen-bonded) in the acetone/methanol/carbon tetrachloride system.

Reilly, John T.; Walsh, John M.; Greenfield, Michael L.; Donohue, Marc D.

1992-10-01

164

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

165

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

166

Raman spectroscopic studies of acid dissociation in sulfonated polystyrene resins  

NASA Astrophysics Data System (ADS)

FT-Raman spectra of sulfonated polystyrene resins with varying levels of sulfonation from 9-97% have been recorded. Molecular markers of -SO 3H and -SO 3- moieties have been proposed and used to determine quantitatively the degree of dissociation of the acids as a function of total sulfonic acid and sulfonate concentrations. Comparison with the ethanesulfonic acid/water system has been made and it is concluded that the low-sulfonation and high-sulfonation resins closely resemble this molecular acid/water system, but that intermediate sulfonation specimens are dissociated some 18% less than the corresponding ethanesulfonic acid/water analogues. This is ascribed to the presence of hydrogen-bonded acid groups with water in the gel region of the resins which had been suggested in previous infrared spectroscopic measurements.

Edwards, H. G. M.; Brown, D. R.; Dale, J. R.; Plant, S.

2001-09-01

167

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

168

A spectroscopic analysis of the most polarizing atomic lines of the second solar spectrum  

NASA Astrophysics Data System (ADS)

We present an analysis of the second solar spectrum, as plotted in graphical form in the three volumes of the atlas “The Second Solar Spectrum”, in the wavelength range between 3160 Å and 6995 Å. All the strongest positive linear polarization signals produced by atomic spectral lines are identified, and their amplitudes are listed, along with the most relevant spectroscopic properties of the lines. The various signals are divided into five classes according to the shape of their Q/I profiles. Three empirical rules are formulated from the analysis of the amplitude and shape of the various signals, and of the spectroscopic properties of the spectral lines. Tables 1 and 2 are only available in electronic form at http://www.aanda.org

Belluzzi, L.; Landi Degl'Innocenti, E.

2009-02-01

169

Synthesis, spectroscopic characterization and comparative DNA binding studies of Schiff base complexes derived from L-leucine and glyoxal.  

PubMed

The mononuclear Schiff base complexes of the type, [ML(CH(3)OH)(2)] [M = Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by template condensation of L-leucine and glyoxal. The complexes have been characterized on the basis of the results of the elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz, FT-IR, Mass, (1)H NMR and (13)C NMR spectra. The UV-vis and magnetic moment data revealed an octahedral geometry around Co(II), Ni(II) ion with distortion around Cu(II) ion complex confirmed by EPR data. The conductivity data show a non-electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that all the complexes exhibit a significant binding to calf thymus DNA. PMID:21807556

Shakir, Mohammad; Shahid, Nida; Sami, Naushaba; Azam, Mohammad; Khan, Asad U

2011-11-01

170

Spectroscopic analysis of local structure and small particles of catalysts  

NASA Astrophysics Data System (ADS)

Most practical catalysts are highly porous and amorphous. In order to characterize them structurally, it is essential to use spectroscopies dependent on penetrating radiation that do not require long range order. It is also very useful if such spectroscopies are element specific so that the local structure around individual elements might be probed. Extended X-ray absorption fine structure (EXAFS) analysis, NMR and Mössbauer spectroscopies meet these requirements. Each spectroscopy is briefly reviewed and examples of applications of two or more of these spectroscopies to several catalytic investigations are presented. The application of EXAFS and NMR to Pt/Al 2O 3, EXAFS and Mössbauer to Pt-Ir/Al 22O 3 and Co-Mo/Al 2O 3, and EXAFS and NMR to Ni-Mo/Al 2O 3 catalysts are discussed.

Haller, Gary L.

1985-02-01

171

Spectroscopic analysis of four post-AGB candidates  

E-print Network

We have done a detailed abundance analysis of four unexplored candidate post- Asymptotic Giant Branch(AGB) stars IRAS 13110 - 6629, IRAS 17579 - 3121, IRAS 18321 - 1401 and IRAS 18489 - 0629 using high resolution spectra. We have constructed Spectral Energy Distributions (SED) for these objects using the existing photometric data combined with infrared (IR) fluxes. For all sample stars, the SEDs exhibit double peaked energy distribution with well separated IR peaks showing the presence of dusty circumstellar material. The CNO abundances indicate the production of N via CN cycling, but observed [C/Fe] indicates the mixing of carbon produced by He burning by third dredge up although C/O ratio remains less that 1. A moderate DG effect is clearly seen for IRAS 18489 - 0629 and IRAS 17579 - 3121 while a large scatter observed in depletion plots for IRAS 18321 - 1401 and IRAS 13110 - 6629 indicate the presence of other processes affecting the observed abundance pattern.

Molina, R E; Pereira, C B; Ferro, A Arellano; Muneer, S

2014-01-01

172

Spectroscopic analysis and DFT calculations of a food additive Carmoisine  

NASA Astrophysics Data System (ADS)

FT-IR and Raman techniques were employed for the vibrational characterization of the food additive Carmoisine (E122). The equilibrium geometry, various bonding features, and harmonic vibrational wavenumbers have been investigated with the help of density functional theory (DFT) calculations. A good correlation was found between the computed and experimental wavenumbers. Azo stretching wavenumbers have been lowered due to conjugation and ?-electron delocalization. Predicted electronic absorption spectra from TD-DFT calculation have been analysed comparing with the UV-vis spectrum. The first hyperpolarizability of the molecule is calculated. Intramolecular charge transfer (ICT) responsible for the optical nonlinearity of the dye molecule has been discussed theoretically and experimentally. Stability of the molecule arising from hyperconjugative interactions, charge delocalization and C-H⋯O, improper, blue shifted hydrogen bonds have been analysed using natural bond orbital (NBO) analysis.

Snehalatha, M.; Ravikumar, C.; Hubert Joe, I.; Sekar, N.; Jayakumar, V. S.

2009-04-01

173

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

174

Spectroscopic analysis of four post-AGB candidates  

NASA Astrophysics Data System (ADS)

We have done a detailed abundance analysis of four unexplored candidate post- Asymptotic Giant Branch(AGB) stars IRAS 13110 - 6629, IRAS 17579 - 3121, IRAS 18321 - 1401 and IRAS 18489 - 0629 using high resolution spectra. We have constructed Spectral Energy Distributions (SED) for these objects using the existing photometric data combined with infrared (IR) fluxes. For all sample stars, the SEDs exhibit double peaked energy distribution with well separated IR peaks showing the presence of dusty circumstellar material. The CNO abundances indicate the production of N via CN cycling, but observed [C/Fe] indicates the mixing of carbon produced by He burning by third dredge up although C/O ratio remains less that 1. A moderate DG-effect is clearly seen for IRAS 18489 - 0629 and IRAS 17579 - 3121 while a large scatter observed in depletion plots for IRAS 18321 - 1401 and IRAS 13110 - 6629 indicate the presence of other processes affecting the observed abundance pattern.

Molina, R. E.; Giridhar, S.; Pereira, C. B.; Arellano Ferro, A.; Muneer, S.

2014-10-01

175

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

PubMed

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

Wang, Chuji; Sahay, Peeyush

2009-01-01

176

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

PubMed Central

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

Wang, Chuji; Sahay, Peeyush

2009-01-01

177

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

2007-02-01

178

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

179

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

180

Precise Theoretical Study of Spectroscopic Constants in Diatomics  

NASA Astrophysics Data System (ADS)

During the last decade a significant progress in methods of molecular spectroscopy was achieved. One of the most important applications of these methods is a measurement of an electron electric dipole moment in diatomic molecules and cations containing heavy elements. In order to speed up such experiments, which usually prepared for many years, one can apply accurate ab initio quantum-chemical methods to predict different spectroscopic constants of a molecule or cation under consideration: scheme of electronic terms, vibrational and rotation constants, hyperfine structure constants, g-factors, lifetimes etc. In such calculations both correlation and relativistic effects should be taken into account. This is not a trivial problem for systems containing transition elements and especially lanthanides and actinides. %Therefore, ``direct'' 4-component Hamiltonians are not always the best choice and some alternative We report results of our recent investigations of a number of diatomics including theoretical investigation of HfF^{+}. Details of used methods are discussed. K. C. Cossel, D. N. Gresh, L. C. Sinclair, T. Coffey, L. V. Skripnikov, A. N. Petrov, N. S. Mosyagin, A. V. Titov, R. W. Field, E. R. Meyer, E. A. Cornell and J. Ye, Chem. Phys. Lett., 546, 1 (2012).

Skripnikov, L. V.; Petrov, A. N.; Titov, A. V.; Mosyagin, N. S.

2013-06-01

181

Spectroscopic Analysis of Sequentially Extracted Humic Acid from Compost  

Microsoft Academic Search

Structural characterization of organic matter (OM) is crucial in assessing its role in soils and sediments. In this study, humic acids (HA) were sequentially extracted from a compost and characterized in terms of their molecular, chemical, and structural heterogeneity. HA was extracted in sequence a total of 28 times, using 0.1 mol L Na4P2O7, and sequentially grouped into seven fractions. These fractions

Karen Heymann; Hamid Mashayekhi; Baoshan Xing

2005-01-01

182

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

183

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

184

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

185

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. PMID:20559489

Kumirska, Jolanta; Czerwicka, Ma?gorzata; Kaczy?ski, Zbigniew; Bychowska, Anna; Brzozowski, Krzysztof; Thöming, Jorg; Stepnowski, Piotr

2010-01-01

186

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

187

Visible\\/uv Spectroscopic Analysis of Plasma Generation from Fine Wires  

Microsoft Academic Search

Summary form only given. Experiments are underway to study plasma generation from fine wires. For these experiments, a capacitive discharge (100kV, 80kA) drives one or more aluminum wires (25-100 microns) to form a plasma. Visible\\/uv spectroscopic diagnostics are employed to obtain spatial and temporal temperature and density profiles. Experiments are conducted in a return current geometry to study the effects

M. D. Johnston; K. Hahn; B. V. Oliver; S. Cordova; T. A. Mehlhorn; D. R. Welch; D. V. Rose; D. W. Droemer; R. L. Starbird; Y. Maron

2007-01-01

188

Solid-State NMR Spectroscopic Study of Phosphate Sorption Mechanisms on Aluminum (Hydr)oxides  

E-print Network

Information ABSTRACT: Sorption reactions occurring at mineral/water interfaces are of fundamental importanceSolid-State NMR Spectroscopic Study of Phosphate Sorption Mechanisms on Aluminum (Hydr)oxides Wei. To advance the understanding of sorption reactions, development of new methodology is required. In this study

Sparks, Donald L.

189

Temperature programmed desorption and infrared spectroscopic studies of thin water films on MgO(100)  

E-print Network

such as physisorption versus chemi- sorption and the orientation of water molecules in the first few monolayers deserveTemperature programmed desorption and infrared spectroscopic studies of thin water films on MgO(100 Abstract Thin water (D2O) films on MgO(100) surfaces have been studied. Water was deposited at 115 K

Reisler, Hanna

190

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

Microsoft Academic Search

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

D. Lacroix; C. Boudot; G. Jeandel

1999-01-01

191

Vibrational Spectroscopic Studies of Aqueous Interfaces: Salts, Acids, Bases, and Nanodrops  

E-print Network

high boiling point of water. Moreover, the surface structure of water, directly related to the hydrogen as it is affected by salts, acids, and ammonia. Cluster studies contribute to understanding the aqueous interfaceVibrational Spectroscopic Studies of Aqueous Interfaces: Salts, Acids, Bases, and Nanodrops Sandhya

192

Spectroscopic analysis of urinary calculi and inhibition of their growth  

NASA Astrophysics Data System (ADS)

We present here a study of kidney stone formation and growth inhibition based on a traditional medicine approach with Aquatica Lour (RAL) herbal extracts. Kidney stone material systems were synthesized in vitro using a simplified single diffusion gel growth technique. With the objective of revealing the mechanism of inhibition of calculi formation by RAL extracts, samples prepared without the presence of extract, and with the presence of extract, were analyzed using Raman, photoluminescence, and XPS. The unexpected presence of Zn revealed by XPS in a sample prepared with RAL provides an explanation for the inhibition process, and also explains the dramatic reflectance of incident light observed in attempts to obtain infrared transmission data. Raman data are consistent with the binding of the inhibitor to the oxygen of the kidney stone. Photoluminescence data corroborate with the other results to provide additional evidence of Zn-related inhibition.

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

2009-10-01

193

Spectroscopic study of gold nanoparticle formation through high intensity laser irradiation of solution  

NASA Astrophysics Data System (ADS)

A spectroscopic study of the gold nanoparticle (NP) formation by high-intensity femtosecond laser irradiation of a gold ion solution was reported. The effect of varying energy density of the laser on the formation of gold NPs was also investigated. The surface plasmon resonance (SPR) peak of the gold nanocolloid in real-time UV-visible absorption spectra during laser irradiation showed a distinctive progress; the SPR absorption peak intensity increased after a certain irradiation time, reached a maximum and then gradually decreased. During this absorption variation, at the same time, the peak wavelength changed from 530 to 507 nm. According to an empirical equation derived from a large volume of experimental data, the estimated mean size of the gold NPs varied from 43.4 to 3.2 nm during the laser irradiation. The mean size of gold NPs formed at specific irradiation times by transmission electron microscopy showed the similar trend as that obtained in the spectroscopic analysis. From these observations, the formation mechanism of gold NPs during laser irradiation was considered to have two steps. The first is a reduction of gold ions by reactive species produced through a non-linear reaction during high intensity laser irradiation of the solution; the second is the laser fragmentation of produced gold particles into smaller pieces. The gold nanocolloid produced after the fragmentation by excess irradiation showed high stability for at least a week without the addition of any dispersant because of the negative charge on the surface of the nanoparticles probably due to the surface oxidation of gold nanoparticles. A higher laser intensity resulted in a higher efficiency of gold NPs fabrication, which was attributed to a larger effective volume of the reaction.

Nakamura, Takahiro; Herbani, Yuliati; Ursescu, Daniel; Banici, Romeo; Dabu, Razvan Victor; Sato, Shunichi

2013-08-01

194

Spectroscopic analysis of four post-AGB candidates  

NASA Astrophysics Data System (ADS)

We have done a detailed abundance analysis of four unexplored candidate post- Asymptotic Giant Branch(AGB) stars IRAS 13110 - 6629, IRAS 17579 - 3121, IRAS 18321 - 1401 and IRAS 18489 - 0629 using high resolution spectra. We have constructed Spectral Energy Distributions (SED) for these objects using the existing photometric data combined with infrared (IR) fluxes. For all sample stars, the SEDs exhibit double peaked energy distribution with well separated IR peaks showing the presence of dusty circumstellar material. The CNO abundances indicate the production of N via CN cycling, but observed [C/Fe] indicates the mixing of carbon produced by He burning by third dredge up although C/O ratio remains less that 1. A moderate DG-effect is clearly seen for IRAS 18489 - 0629 and IRAS 17579 - 3121 while a large scatter observed in depletion plots for IRAS 18321 - 1401 and IRAS 13110 - 6629 indicate the presence of other processes affecting the observed abundance pattern. %Z Arellano Ferro, A. 1981, PASP, 93, 351 ibidrule 1985, RMA&A, 11, 113 Bonifacio, P., Caffau, E., & Molaro, P. 2000, A&AS, 145, 473 Boothroyd, A.I., & Sackmann, I.J. 1999, ApJ, 510, 232 Castelli, F., & Kurucz, R.L. 2003, in Modelling of Stellar Atmospheres, ed. Piskunov N., Weiss W.W., Gray D.F., Proc. IAU Symp. 210, (Astron. Soc. Pac., San Fransisco) A20 Clarke, A.J., Oudmaijer, R.D., & Lumsden, S.L. 2005, MNRAS, 363, 1111 Cutri, R.M., et al. 2003, VizieR On-Line Data Catalog: II/246 Deroo, P., Acke, B., Verhoelst, T., Dominik, C., Tatulli, E., & van Winckel, H. 2007, A&A, 474, 45 De Ruyter, S., van Winckel, H., Maas, T., Lloyd Evans, T., Waters, L.B.F.M., & Dejonghe, H., 2006 A&A, 448, 641 Fiorucci, M, Munari, U., 2003 A&A, 401, 781 García-Lario, P., Manchado, P., Pych, W., & Pottasch, S.R. 1997, A&AS, 126, 479 García-Lario, P. 2006, in Planetary Nebulae in our Galaxy and Beyond, Proceedings of the International Astronomical Union, Symposium #234. Edited by Michael J. Barlow and Roberto H. Méndez. (Cambridge: Cambridge University Press 2006) 63 García-Segura, G., López J.A., & Franco, J. 2005, ApJ, 618, 919 Gehren, T., Liang, Y.C., Shi, J.R., Zhang, H.W., & Zhao, G. 2004, A&A, 413, 1045 Giridhar, S. 2011, ASInC, 3, 39 Giridhar, S., Lambert, D.L., & González, G. 2000, ApJ, 531, 521 Giridhar, S., Lambert, D. L., Reddy, B. E., Gonzalez, G., & Yong, D. 2005, ApJ, 627, 432 Gómez, J.F., Suárez, O., Gómez, Y., Miranda, L.F., Torrelles, J.M., Anglada, G., & Morata, O. 2008, AJ, 135, 2074 Gronewegen, M.A.T., & de Jong, T. 1993, A&A, 267, 410 Herwig, F. 2004, ApJS, 155, 651 ibidrule 2005, ARA&A, 43, 435 Hog, E., et al. 2000, A&A, 355, L27-30 Iben, I., & Renzini, A. 1983, ARA&A, 21, 271 Jacoby, G.H., Hunter, D.A., & Christian, C.A. 1984, ApJS, 56, 257 Kameswara Rao, & N., Reddy, B.E. 2005, MNRAS, 357, 235 Karakas, A.I., Lattanzio, J.C., & Pols, O.R. 2002, PASA, 19, 515 Kaufer, A., et al. 1999, The Messenger, 95, 8 Kiss, L.L., Derekas A., Szabó, Gy. M., Bedding T.R., & Szabados L. 2007, MNRAS, 375, 1338 Klochkova, V.G., & Panchuk, V.E. 2012, Astron. Rep., 56, 104 Kurucz, R. L. 1991, Precision Photometry: Astrophysics of the Galaxy, 27 Lind, K., Asplund, M., Barklem, P.S., & Belyaev, A.K. 2011, A&A, 528, 103 Lodders, K. 2003, ApJ, 591, 1220 Luck, R.E., & Bond, H.E. 1989, ApJ, 342, 476 Molina, R.E. 2012, RMxAA, 48, 95 Pereira, C.B., & Miranda, L.F. 2007, A&A, 462, 231 Perryman, M.A.C. 1997, ESA - SP 1200, 0 Pojmanski, G. 2002, Acta Astronomica, 52,397 Perryman, M.A.C., 1997, ESA - SP 1200, 0 Preite-Martínez, A. 1988, A&AS, 76, 317 Ratag, M.A., Pottasch, S.R., Zijlstra, A.A., &Menzies, J, 1990, A&A, 233, 181 Steenman, H., & The, P. S. 1991, Ap&SS, 184, 9 Sahin, T., & Lambert, D.L. 2009, MNRAS, 398, 1730 Silva, A.M., Azcarate, I.N., Poppel, W.G.L., & Likkel, L. 1993, A&A, 275, 510 Schiller, F., & Przybilla, N. 2008, A&A, 479, 849 Schlegel, D.J., Finkbeiner, D.P., & Davis, M. 1998, A

Molina, R. E.; Giridhar, S.; Pereira, C. B.; Arellano Ferro, A.; Muneer, S.

2014-10-01

195

[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

196

Chemical analysis of exhaled human breath using a terahertz spectroscopic approach  

NASA Astrophysics Data System (ADS)

As many as 3500 chemicals are reported in exhaled human breath. Many of these chemicals are linked to certain health conditions and environmental exposures. This experiment demonstrated a method of breath analysis utilizing a high resolution spectroscopic technique for the detection of ethanol, methanol, and acetone in the exhaled breath of a person who consumed alcohol. This technique is applicable to a wide range of polar molecules. For select species, unambiguous detection in a part per trillion dilution range with a total sample size in a femtomol range is feasible. It compares favorably with other methods of breath analysis.

Fosnight, Alyssa M.; Moran, Benjamin L.; Medvedev, Ivan R.

2013-09-01

197

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

NASA Technical Reports Server (NTRS)

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

Walker, A. B. C., Jr.

1975-01-01

198

Spectroscopic studies of molybdenum complexes as models for nitrogenase  

SciTech Connect

Because biological nitrogen fixation requires Mo, there is an interest in inorganic Mo complexes which mimic the reactions of nitrogen-fixing enzymes. Two such complexes are the dimer Mo/sub 2/O/sub 4/ (cysteine)/sub 2//sup 2 -/ and trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ (dppe = 1,2-bis(diphenylphosphino)ethane). The H/sup 1/ and C/sup 13/ NMR of solutions of Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ are described. It is shown that in aqueous solution the cysteine ligands assume at least three distinct configurations. A step-wise dissociation of the cysteine ligand is proposed to explain the data. The Extended X-ray Absorption Fine Structure (EXAFS) of trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ is described and compared to the EXAFS of MoH/sub 4/(dppe)/sub 2/. The spectra are fitted to amplitude and phase parameters developed at Bell Laboratories. On the basis of this analysis, one can determine (1) that the dinitrogen complex contains nitrogen and the hydride complex does not and (2) the correct Mo-N distance. This is significant because the Mo inn both complexes is coordinated by four P atoms which dominate the EXAFS. A similar sort of interference is present in nitrogenase due to S coordination of the Mo in the enzyme. This model experiment indicates that, given adequate signal to noise ratios, the presence or absence of dinitrogen coordination to Mo in the enzyme may be determined by EXAFS using existing data analysis techniques. A new reaction between Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ and acetylene is described to the extent it is presently understood. A strong EPR signal is observed, suggesting the production of stable Mo(V) monomers. EXAFS studies support this suggestion. The Mo K-edge is described. The edge data suggests Mo(VI) is also produced in the reaction. Ultraviolet spectra suggest that cysteine is released in the course of the reaction.

Walker, T.P.

1981-05-01

199

THE APPLICATION OF SPECTROSCOPIC STUDIES OF THE AURORA TO THERMOSPHERIC NEUTRAL  

E-print Network

THE APPLICATION OF SPECTROSCOPIC STUDIES OF THE AURORA TO THERMOSPHERIC NEUTRAL COMPOSITION D abundance in the aurora1 thermosphere is investigated using observations acquired at Poker Flat, Alaska to transitions in 0' and NT ions, respectively, is computed for a range of characteristic energies of aurora1

Lummerzheim, Dirk

200

Speciation of heavy metals in cement-stabilized waste forms: A micro-spectroscopic study  

E-print Network

whether the locally observed Ni and Co phases are representative of the entire cement system. 2. Method 2.1. Sample preparation The cement samples were prepared from a com- mercial sulfate-resisting Portland cementSpeciation of heavy metals in cement-stabilized waste forms: A micro-spectroscopic study M. Vespa

201

Spectroscopic and Electronic Structure Studies of the Diamagnetic Side-On CuII  

E-print Network

Spectroscopic and Electronic Structure Studies of the Diamagnetic Side-On CuII -Superoxo Complex Cu to elucidate the electronic structure of the diamagnetic mononuclear side-on CuII -superoxo complex. The electronic nature of its lowest singlet/triplet states and the ground-state diamagnetism are explored

Chen, Peng

202

Sulfates on Mars: A systematic Raman spectroscopic study of hydration states of magnesium sulfates  

E-print Network

Sulfates on Mars: A systematic Raman spectroscopic study of hydration states of magnesium sulfates of magnesium sulfates on the martian surface. In situ identification of the hydration states of magnesium of magnesium sulfate. Characteristic and distinct Raman spectral patterns were observed for each of the 11

203

Influence of a superficial layer in the quantitative spectroscopic study of strongly scattering media  

E-print Network

Influence of a superficial layer in the quantitative spectroscopic study of strongly scattering media Maria Angela Franceschini, Sergio Fantini, L. Adelina Paunescu, John S. Maier, and Enrico Gratton and the reduced scattering s eff coefficients measured on the surfaces of two-layered turbid media, using

Boas, David

204

Kinetic and infrared spectroscopic studies of ionic reactions of interest to various plasma media  

Microsoft Academic Search

A selected ion flow tube (SIFT) and a Flowing Afterglow (FA) with extensive spectroscopic facilities were used in the kinetic and dynamic studies of gas phase reactions between ions, electrons, and neutral atoms and molecules. Along with the interest, these reactions have importance in planetary atmospheres, interstellar gas clouds, circumstellar shells, comets, laser plasmas, combustion flames, and etchant plasmas. SIFT

Ted Lee Williams

1999-01-01

205

Fluorescence excitation spectroscopic study of the jet-cooled acetyl cyanide  

E-print Network

Fluorescence excitation spectroscopic study of the jet-cooled acetyl cyanide Min-Chul Yoon, Young S Received 21 October 1998; accepted 19 January 1999 Fluorescence excitation spectrum of acetyl cyanide (CH3 Institute of Physics. S0021-9606 99 00515-2 I. INTRODUCTION Photochemistry of acetyl cyanide

Kim, Sang Kyu

206

Chemical Treatment Effect of Si(111) Surfaces in NH4F Solution Studied by Spectroscopic Ellipsometry  

Microsoft Academic Search

Chemically treated Si(111) surfaces in NH4F (40%) solution at 20° C have been studied using spectroscopic ellipsometry (SE) and exsitu atomic force microscopy (AFM). The SE data clearly indicate that the solution causesthe removal of the native oxide with an etch rate of ˜ 15 Å\\/min. Just after the native oxide is etched away completely (t˜ 70 s), the SE

Takahiro Suzuki; Sadao Adachi

1994-01-01

207

Far infrared time domain terahertz spectroscopic study of Ho2Ti2O7  

NASA Astrophysics Data System (ADS)

We report a far infrared time domain terahertz spectroscopic study of the spin ice material holmium titanate. The complex dielectric constant was obtained in the terahertz frequency range. Several low energy excitations were identified from the optical spectra. We will discuss the possible nature of those excitations and their relevance to the spin ice physics.

Pan, Lidong; Valdes Aguilar, R.; Cava, R. J.; Koohpayeh, S. M.; Armitage, N. Peter

2012-02-01

208

A Systematic Spectroscopic X-Ray Study of Stellar Coronae with XMM-Newton: Early Results  

E-print Network

-term evolution of stellar coronae. Complemented by targets from the calibration and performance veri#12;cationA Systematic Spectroscopic X-Ray Study of Stellar Coronae with XMM-Newton: Early Results M. G conducting a comprehensive survey of stellar coronae with the XMM-Newton Re ection Grating Spectrometers

Audard, Marc

209

Spectroscopic Studies of Low-Pressure Flames; Temperature Measurements in Acetylene Flames  

Microsoft Academic Search

Flames at very low pressure have a relatively thick reaction zone (or flame front) and are especially suitable for detailed study of the combustion processes and of the distribution of energy during the reaction. Temperature measurements have been made, by various spectroscopic methods, on flames of acetylene with air, oxygen and nitrous oxide, in some cases down to a pressure

A. G. Gaydon; H. G. Wolfhard

1948-01-01

210

Vibrational spectroscopic study of hydroxylpyromorphite-hydroxylmimetite solid solutions  

NASA Astrophysics Data System (ADS)

Hydroxylpyromorphite Pb5(PO4)3OH and hydroxylmimetite Pb5(AsO4)3OH minerals belong to the apatite supergroup. Their structure allows isomorphous substitutions in both cationic and anionic positions. They are isostructural with pyromorphite Pb5(PO4)3Cl and mimetite Pb5(AsO4)3OH which are the end products of in situ phosphate induced remediation of soils polluted with heavy metals e.g. lead. The research objective was to synthesize and characterize the members of above mentioned solid solution. The minerals were synthesized at room temperature and analyzed by X-Ray diffraction and Infrared spectroscopy (FTIR-DRIFT). The product syntheses was crystalline phase without any impurities within the detection limit of XRD. Shifts of certain diffraction peaks were observed in solid solution series due to replacement PO4 after AsO4. The bands v3 and v4 attributed to vibrations in the PO4 and AsO4 tetrahedra appear at 1050-790 and 580-534 cm-1. Due to difference in atomic mass of P and As as well as bonding strength of P-O and As-O the skeletal bands shift to lower wavenumbers with the increase of AsO4 substitution. The correlation between the position of vibrational modes and the chemical composition is observed. The OH stretching mode in the FTIR spectra appears in the range of 3765-3552 cm-1 as a sharp band for the end members of the solid solution. For the intermediate minerals the OH band becomes complex. The analysis of deconvoluted OH bands indicated several vibrational modes which suggested a significant change of OH group local environment induced by substitutions. The study was supported by the AGH University of Science and Technology (Krakow, Poland) as the research project No. 307 473 638.

Kwa?niak-Kominek, Monika; Matusik, Jakub; Bajda, Tomasz; Manecki, Maciej

2013-04-01

211

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

212

1H NMR spectroscopic studies establish that heparanase is a retaining glycosidase.  

PubMed

Heparanase is an endo-?-glucuronidase that cleaves heparan sulfate side chains of proteoglycans in basement membranes and the extracellular matrix (ECM). Heparanase is implicated in several diverse pathological processes associated with ECM degradation such as metastasis, inflammation and angiogenesis and is thus an important target for anti-cancer and anti-inflammatory drug discovery. Heparanase has been classed as belonging to the clan A glycoside hydrolase family 79 based on sequence analysis, secondary structure predictions and mutagenic analysis, and thus it has been inferred that it is a retaining glycosidase. However, there has been no direct experimental evidence to support this conclusion. Herein we describe (1)H NMR spectroscopic studies of the hydrolysis of the pentasaccharide substrate fondaparinux by heparanase, and provide conclusive evidence that heparanase hydrolyses its substrate with retention of configuration and is thus established as a retaining glycosidase. Knowledge of the mechanism of hydrolysis may have implications for future design of inhibitors for this important drug target. PMID:24291708

Wilson, Jennifer C; Laloo, Andrew Elohim; Singh, Sanjesh; Ferro, Vito

2014-01-01

213

A Quantitative Spectroscopic Study of the Metallic - Stars.  

NASA Astrophysics Data System (ADS)

We have undertaken a study designed to determine, as accurately and as consistently as possible, the physical properties of a group of metallic-line stars. We have obtained observational data that are of higher resolution and that cover a wider spectral range than have any previous authors. Our analysis has been carried out with the most sophisticated methods available, including line-blanketed model atmospheres of differing composition and spectral synthesis techniques. We observed the Am star 81 Tauri to undergo a transient change in its energy distribution over a period of five days. It appears that several other Am stars have displayed this sort of phenomenon in the past and it may be more common than has previously been believed. We have determined effective temperatures and surface gravities for our programme stars by comparing our observed energy distributions to fluxes calculated from model atmospheres that have line-blanketing which reflect solar, three times solar and ten times solar abundances. The theoretical fluxes calculated with the three times solar models provide the best fit to the observed energy distributions and are consistent with the surface gravities determined from the ionization equilibrium of iron. We have used these models to synthesize the Ca K line profiles in our stars and for suitable calcium abundances, and match between theory and observation is excellent. We have calculated the radii of our programme stars and find them to be similar to those of normal A -type stars of the same effective temperature. The radii are thus consistent with normal main sequence gravities. We have determined the rotational and microturbulent velocities of these stars using spectral synthesis techniques. The rotational velocities are small and similar to those determined by other authors. The microturbulent velocities are much smaller than those determined by the classical curve-of -growth techniques. This results in a microturbulent scale for Am stars similar to that for normal A dwarfs. We have used spectral synthesis techniques in combination with high resolution International Ultraviolet Explorer Satellite spectra to investigate the abundances of the lighter elements, many of which cannot be studied in the visual. We find nitrogen to range from slightly overabundant in the cooler Am stars to slightly underabundant in the hotter Am stars. Carbon is underabundant by almost a factor of two, aluminium is solar, phosphorus is fifteen times overabundant and silicon ranges from solar to ten times overabundant. We have investigated the helium abundance in Am stars and find some evidence that it may be temperature dependant. If this is true, helium may be far more deficient, by up to a factor of thirty, in the coolest Am stars than has previously been believed. When our abundance calculations are carried out with helium deficient models, there are small changes in the abundance of some of the lighter elements in the sense that they become more solar. We have compared the results of our abundance determinations to the published results of diffusion theory. The process is somewhat confusing and our results are not conclusive. Many of the tests we have performed support diffusion theory, some do not. Finally, we have combined our data with those of Heacox (1979) for the Hg-Mn stars. We have found substantial observational evidence for a connection between these classes. We believe that they form a continuous sequence of non-magnetic peculiar stars.

Lane, Mary Catherine

214

Spectroscopic Studies of Diatomic Transition Metal Oxides and Fluorides.  

NASA Astrophysics Data System (ADS)

Wavelength selected fluorescence excitation spectroscopy (WSFES) techniques and ligand field theory (LFT) calculations have been applied to the following transition metal diatomics: CeO, UO, LaF, YF, ScF, HfO, TiO, and ZrO. All of the rotational spectra recorded for these molecules were at a resolution of 0.03 cm^{-1}, and, with few exceptions, Omega assignments for electronic states were unambiguously determined from observations of the first lines in at least two rotational branches. Accurate term energies and rotational constants are reported. Thirty one electronic transitions of CeO were recorded, and all of the sixteen states that correlate with rm Ce^{2+}(4f6s)O^ {2-} were characterized. The results are in good accord with a ligand field theory model of the low-lying states. New assignments were established for four previously observed transitions, and spectra for three new excited states were analyzed. LFT calculations have been used in an attempt to provide configurational assignments for the excited states (including those from previous studies). Twenty two states are tentatively assigned to the rm Ce^{2+}(4f6p)O ^{2-} configuration. Twelve others are tentatively assigned to rm Ce^ {2+}(4f5d)O^{2-}.. Rotation-electronic interactions between states of the 4f6s configuration of CeO, mediated by the operator {-}B(R)( J^+ cdot J_sp{a}{-}+ J^-cdot J_sp{a} {+}), have been calculated. Second-order perturbation theory was used to account for the effect of heterogeneous interactions on the rotation constants within a single configuration. Thirty-three electronic transitions of UO were analyzed, and nine low-lying electronic states that correlated with either rm U^{2+}(5f ^37s)O^{2-} or rm U^{2+}(5f^27s^2)O ^{2-} were characterized. Ligand field theory calculations were also used in an attempt to provide configurational assignments for the excited states of UO and ThO. Experimentally derived values for Delta B_sp{0} {0}(nl/n^' l^') parameters were used to predict the electronic structures of UO and UO^+.. Eight electronic transitions of LaF and nine transitions of YF were studied. LFT calculations (and in the case of LaF, hyperfine constants) were used to suggest electronic configurational assignments for the excited states of these molecules. WSFE spectra of the 0-0 and 1-1 bands of the ScF F^1Phi-A^1 Delta transition were observed, and perturbations in the F^1Phi state, caused by interactions with the h^3Pi_2 state, were analyzed. Using a method based on Franck-Condon factors, the vibrational numbering in the perturbing h^3Pi_2 state was estimated. The 5698 A band of HfO has been re examined. The wavelength-resolved fluorescence excitation technique was used to record the (2,0) band of the C ^3Delta_3-a^1 Delta transition, and the (2,3) and (2,4) bands of the C^3Delta_3 -X^3Delta_3 electronic transition of TiO. The (0,0) bands of the satellite e^3 Pi_1-a^3Delta _1 and e^3Pi_2 -a^3Delta_2 transitions of ZrO were investigated, and these data were combined with previous high resolution analyses of the ZrO beta-system and with the analysis of the intercombination e^3Pi_1 -X^1Sigma ^+ transition to obtain accurate term energies for the triplet states of ^{90 }Zr^{16}O. (Abstract shortened by UMI.).

McCord, John Edward

215

Fourier-transform Raman spectroscopic study of frankincense and myrrh  

NASA Astrophysics Data System (ADS)

The application of FT-Raman spectroscopy to the non-destructive analysis of natural resins is illustrated here with several samples of two natural resins; frankincense and myrrh. Both resins are multicomponent systems and comparison of the spectra of the two resins with those of individual samples from each resin was effected. This leads to a means of identifying, frankincense and myrrh of differing concentrations of constituent species, using FT-Raman spectroscopy. The samples were not pre-treated before analysis and were used directly from their respective storage collections.

Edwards, H. G. M.; Falk, M. J.

1997-11-01

216

Fouriertransform Raman spectroscopic study of frankincense and myrrh  

Microsoft Academic Search

The application of FT-Raman spectroscopy to the non-destructive analysis of natural resins is illustrated here with several samples of two natural resins; frankincense and myrrh. Both resins are multicomponent systems and comparison of the spectra of the two resins with those of individual samples from each resin was effected. This leads to a means of identifying, frankincense and myrrh of

H. G. M. Edwards; M. J. Falk

1997-01-01

217

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

218

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

219

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

220

Spectroscopic study of the color characteristics of dyed fabrics  

Microsoft Academic Search

The aim of the present work was the qualitative and quantitative analysis of the changes in the color characteristics of fabric dyes relative to their characteristics in solution. Fabrics type 32494 (viscose) and type 520 (cotton) which were subjected to direct dyeing by a light-fast blue KU dye, light-fast green G dye, and light-fast red and orange dyes were selected

N. V. Borodai; S. G. Guminetskii; E. S. Smolenskii

1979-01-01

221

?-Cyclodextrin polymer nanoparticles as carriers for doxorubicin and artemisinin: a spectroscopic and photophysical study.  

PubMed

The association of doxorubicin (DOX) and artemisinin (ART) to a ?-CyD-epichlorohydrin crosslinked polymer (p?-CyD), organized in nanoparticles of ca. 15 nm size, was investigated in neutral aqueous medium by circular dichroism (CD), UV-vis absorption and fluorescence. The stability constants and the absolute CD spectra of the drug complexes were determined by global analysis of multiwavelength data from spectroscopic titrations. The polymer p?-CyD proved able to disrupt the DOX dimer when the latter is the predominant form of DOX in solution. The spectroscopic and photophysical properties of the complexes evidenced an alcohol-like environment for ART and an improved inherent emission ability for DOX in the nanoparticle frame. PMID:22576059

Anand, Resmi; Manoli, Francesco; Manet, Ilse; Daoud-Mahammed, Samia; Agostoni, Valentina; Gref, Ruxandra; Monti, Sandra

2012-08-01

222

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.

Sandison, David R. (Edgewood, NM)

1998-01-01

223

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

224

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

225

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

PubMed Central

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

226

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

227

WIYN Open Cluster Study. LX. Spectroscopic Binary Orbits in NGC 6819  

NASA Astrophysics Data System (ADS)

We present the current state of the WOCS radial-velocity (RV) survey for the rich open cluster NGC 6819 (2.5 Gyr) including 93 spectroscopic binary orbits with periods ranging from 1.5 to 8000 days. These results are the product of our ongoing RV survey of NGC 6819 using the Hydra Multi-Object Spectrograph on the WIYN 3.5 m telescope. We also include a detailed analysis of multiple prior sets of optical photometry for NGC 6819. Within a 1° field of view, our stellar sample includes the giant branch, the red clump, and blue straggler candidates, and extends to almost 2 mag below the main sequence (MS) turnoff. For each star observed in our survey we present all RV measurements, the average RV, and velocity variability information. Additionally, we discuss notable binaries from our sample, including eclipsing binaries (WOCS 23009, WOCS 24009, and WOCS 40007), stars noted in Kepler asteroseismology studies (WOCS 4008, WOCS 7009, and WOCS 8007), and potential descendants of past blue stragglers (WOCS 1006 and WOCS 6002). We find the incompleteness-corrected binary fraction for all MS binaries with periods less than 104 days to be 22% ± 3% and a tidal circularization period of 6.2^{+1.1}_{-1.1} days for NGC 6819.

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

2014-08-01

228

WIYN Open Cluster Study. LX. Spectroscopic Binary Orbits in NGC 6819  

E-print Network

We present the current state of the WOCS radial-velocity (RV) survey for the rich open cluster NGC 6819 (2.5 Gyr) including 93 spectroscopic binary orbits with periods ranging from 1.5 to 8,000 days. These results are the product of our ongoing RV survey of NGC 6819 using the Hydra Multi-Object Spectrograph on the WIYN 3.5 m telescope. We also include a detailed analysis of multiple prior sets of optical photometry for NGC 6819. Within a 1-degree field of view, our stellar sample includes the giant branch, the red clump, and blue straggler candidates, and extends to almost 2 mag below the main-sequence (MS) turnoff. For each star observed in our survey we present all RV measurements, the average RV and velocity variability information. Additionally, we discuss notable binaries from our sample, including eclipsing binaries (WOCS 23009, WOCS 24009, and WOCS 40007), stars noted in Kepler asteroseismology studies (WOCS 4008, WOCS 7009, and WOCS 8007), and potential descendants of past blue stragglers (WOCS 1006 a...

Milliman, Katelyn E; Geller, Aaron M; Gosnell, Natalie M; Meibom, Søren; Platais, Imants

2014-01-01

229

Hunting the Parent of the Orphan Stream. II. The First High-resolution Spectroscopic Study  

NASA Astrophysics Data System (ADS)

We present the first high-resolution spectroscopic study on the Orphan stream for five stream candidates, observed with the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Clay telescope. The targets were selected from the low-resolution catalog of Casey et al.: three high-probability members, one medium, and one low-probability stream candidate were observed. Our analysis indicates that the low- and medium-probability targets are metal-rich field stars. The remaining three high-probability targets range over ~1 dex in metallicity, and are chemically distinct compared to the other two targets and all standard stars: low [?/Fe] abundance ratios are observed, and lower limits are ascertained for [Ba/Y], which sit well above the Milky Way trend. These chemical signatures demonstrate that the undiscovered parent system is unequivocally a dwarf spheroidal galaxy, consistent with dynamical constraints inferred from the stream width and arc. As such, we firmly exclude the proposed association between NGC 2419 and the Orphan stream. A wide range in metallicities adds to the similarities between the Orphan stream and Segue 1, although the low [?/Fe] abundance ratios in the Orphan stream are in tension with the high [?/Fe] values observed in Segue 1. Open questions remain before Segue 1 could possibly be claimed as the "parent" of the Orphan stream. The parent system could well remain undiscovered in the southern sky. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

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

2014-03-01

230

A combined spectroscopic and theoretical study of propofol·(H2O)3.  

PubMed

Propofol (2,6-di-isopropylphenol) is probably the most widely used general anesthetic. Previous studies focused on its complexes containing 1 and 2 water molecules. In this work, propofol clusters containing three water molecules were formed using supersonic expansions and probed by means of a number of mass-resolved laser spectroscopic techniques. The 2-color REMPI spectrum of propofol[middle dot](H(2)O)(3) contains contributions from at least two conformational isomers, as demonstrated by UV/UV hole burning. Using the infrared IR/UV double resonance technique, the IR spectrum of each isomer was obtained both in ground and first excited electronic states and interpreted in the light of density functional theory (DFT) calculations at M06-2X/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels. The spectral analysis reveals that in both isomers the water molecules are forming cyclic hydrogen bond networks around propofol's OH moiety. Furthermore, some evidences point to the existence of isomerization processes, due to a complicated conformational landscape and the existence of multiple paths with low energy barriers connecting the different conformers. Such processes are discussed with the aid of DFT calculations. PMID:22920116

León, Iker; Cocinero, Emilio J; Millán, Judith; Rijs, Anouk M; Usabiaga, Imanol; Lesarri, Alberto; Castaño, Fernando; Fernández, José A

2012-08-21

231

Spectroscopic study of coal structure and reactivity: Annual report  

SciTech Connect

The purpose of this project is the development of numerical methods for the quantitative analysis of coals by Fourier transform infrared (FT-IR) spectrometry. The infrared spectra of coal and coal extracts consist of complex bands containing many closely overlapped peaks, and resolution enhancement techniques must be used if quantitative data are to be obtained. During the first year of this project, three major areas have been covered: (1) the effect of optical geometry on the diffuse reflectance infrared spectra of coals; (2) the development of numerical methods for resolution enhancement and quantitative measurements of complex spectra; and (3) the effect of rank and particle size on the rate of air oxidation of bituminous coals. The first sub-project, concerning the effect of optical geometry on the diffuse reflectance infrared spectra of coals has been completed. 17 refs., 9 figs., 4 tabs.

Griffiths, P.R.

1988-01-01

232

Mössbauer spectroscopic study of iron in Victorian brown coal  

NASA Astrophysics Data System (ADS)

The forms of non-pyritic Fe in a suite of Victorian brown coals have been determined by 57Fe Mössbauer analysis. The dominant Fe phase is a poorly-ordered ferric oxyhydroxide with a magnetic ordering temperature of (530 ± 50) K and particle size of approximately 50 Å. Upon exposure of the coal to air, this phase slowly crystallises to goethite. Most of the remaining Fe occurs as a high-spin Fe(II) species attributed to dissolved and hence mobile, Fe(II) humate, which precipitates as the ferric oxyhydroxide to an extent determined by the pH. A third species, present in a much lower concentration, appears to exhibit a transition from low-spin to high-spin Fe(II) as water is removed from the coal.

Cook, P. S.; Cashion, J. D.

1987-06-01

233

Archival Ultraviolet Spectroscopic Analysis of Disk-Dominated Cataclysmic Variables: The Importance of the Boundary Layer  

NASA Astrophysics Data System (ADS)

We propose to carry out a systematic ultraviolet (UV) spectral analysis of 43 disk- dominated systems in cataclysmic variable (CV) binaries with the inclusion of the contribution from the boundary layer, from NASA UV Space Missions such as HST, FUSE, HUT, IUE and ORFEUS. The mass accretion in CVs is a badly needed parameter to verify the theory of the evolution of CVs, to understand the accretion process itself and the disk instability. However, many disk-dominated systems unexpectedly prove impossible to model using only standard accretion disks and white dwarfs in combination. Our objective is to overcome this difficulty by modeling the UV spectrum of the boundary layer between the star and disk, including its effect on the spectrum of the disk and star for the first time. This will provide the first step needed for the improvement of the disk model in UV spectroscopic analysis of disk-dominated systems in CVs. At the same time the results of this spectral analysis will provide information on the boundary layer and accretion disk of these systems. As a by-product, we will create a web-based catalog of all the archival UV spectra of disk-dominated CVs, which will be added and fused to our existing and growing web-based catalog of FUSE spectra of CVs. Since the WD is the most common end-product of stellar evolution (approx 90% of all the stars in the Galaxy have or will evolve into white dwarfs), and the accretion disk is the most common universal structure resulting from mass transfer with angular momentum, and since both can be directly viewed in CVs in the ultraviolet (UV), an understanding of the consequences of accretion in these systems is the first step in a global understanding of accretion in other systems throughout the universe. These include Young Stellar Objects, galactic binaries (accretion onto neutron stars and black holes) and the most difficult to study, Active Galactic Nuclei. In addition, the formation history of WDs is closely linked to the history of the Galaxy. As a consequence, this proposal will support the NASA Strategic Goals and Science Outcomes 3D: Discover the origin, structure, evolution, and destiny of the universe, and search for Earth-like planets; Science Objective 3: understanding the development of structure and cycles of matter and energy in the evolving universe: RFA (b) Explore the behavior of matter in extreme astrophysical environments, including disks, cosmic jets, and the source of gamma-ray bursts and cosmic rays.

Godon, Patrick

234

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

235

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

236

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

237

Special targets for nuclear reaction and spectroscopic studies  

SciTech Connect

Strongly focused and monoenergetic charged-particle beams from modern accelerators and targets fabricated from quantities of isotopically enriched and stable materials are the essential components from many current nuclear physics experiments. Although a large body of this kind of experimental work requires substantial amounts of target material, an important subset of such experiments can be done with as little as a few ..mu..g of material. Experiments where charged particles or electrons can be focused on or transported to a detector are examples of accelerator-based studies which can be made with targets that contain relatively small amounts of material. For these kinds of studies, it then becomes possible to extend the domain of potential target materials to species which are very rare or which are unstable and undergo radioactive decay. At our laboratory during the last ten years, we have made targets for nuclear spectroscopy studies of /sup 152/Eu (13.4y), /sup 154/Eu (8.5y), /sup 249/Bk (320d), /sup 151/Sm (90y), and /sup 148/Gd (75y). We will report our experience with fabricating these and other kinds of stable targets and discuss our plans for preparing additional targets which offer interesting and exciting prospects for future nuclear research studies. 12 refs., 1 fig., 2 tabs.

Lanier, R.G.

1987-07-31

238

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

239

Electrochemical and spectroscopic studies of fuel cell reactions  

Microsoft Academic Search

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

Minhua Shao

2006-01-01

240

EXAFS spectroscopic studies of uranium(VI) oxide precipitates  

SciTech Connect

To accurately model radionuclide migration, it is important to identify the source terms and determine their speciation (i.e., thermodynamics, red-ox properties, molecular structure). The authors 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 form 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{double_bond}U{double_bond}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). Chemical Sciences Div.; [Lawrence Livermore National Lab., CA (United States). Seaborg Inst. for Transactinium Science; Shuh, D.K.; Bucher, J.J.; Edelstein, N.M. [Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.; Palmer, C.E.A.; Marquez, L.N. [Lawrence Livermore National Lab., CA (United States). Seaborg Inst. for Transactinium Science

1997-08-01

241

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

242

Negative ion photoelectron spectroscopic studies of transition metal cluster  

Microsoft Academic Search

The studies reported in this thesis were performed using a negative ion photoelectron spectrometer consisting of a cold cathode DC discharge ion source, a flowing afterglow ion-molecule reactor, a magnetic sector mass analyzer, an argon ion laser for photodetachment and a hemispherical electron kinetic energy analyzer and microchannel plate detector for photoelectron spectrum generation. The 476.5 nm (2.601 eV), 488.0

Timothy Paul Marcy

1999-01-01

243

IR spectroscopic study of the reactivity of aromatic 5-acyltetrazoloisoindoles  

Microsoft Academic Search

An IR study of the 5-acyl tetrazoloisoindoles solvent sensitive bands permit to assign the bands associated to the valence mode of the C?O bond in the 1700–1500 cm?1 area. This provides an explanation of the unusual stability of these newly synthesised compounds. Moreover, in air exposed solutions we observe the formation of unique degradation products. A mechanism for their formation

Z. V. Voitenko; M. Th. Boisdon; T. V. Yegorova; J. Favrot; J. G. Wolf

2003-01-01

244

Spectroscopic studies of the structural properties of Ni substituted  

Microsoft Academic Search

Microstructure and local structure of spinel LiNixMn2 ? xO4 (x=0, 0.1 and 0.2) were studied using X-ray diffraction (XRD) and a combination of X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge spectroscopy (XANES) and Raman scattering with the aim of getting a clear picture of the local structure of the materials responsible for the structural stability of LiNixMn2 ? xO4.

Yingjin Wei; Kyung Wan Nam; Kwang Bum Kim; Gang Chen

245

Cyclodextrins-Kaempferol Inclusion Complexes: Spectroscopic and Reactivity Studies  

Microsoft Academic Search

The slightly water-soluble flavonoid kaempferol (KAE) and its inclusion complexes with ?-cyclodextrin (?CD), hydroxypropyl-?-cyclodextrin (HP?CD) or heptakis-2,6-O-dimethyl-?-cyclodextrin (DM?CD) were investigated. The stoichiometric ratios and association constants describing the extent of the formation of the complexes\\u000a have been determined. Binding constants, estimated from fluorescence studies at different temperatures, were analyzed so as\\u000a to gain information about the mechanisms involved in the

Carolina Jullian; Victor Brossard; Iván Gonzalez; Muriel Alfaro; Claudio Olea-Azar

2011-01-01

246

Spectroscopic studies of model polar stratospheric cloud films  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

247

Spectroscopic, thermal and structural studies on manganous malate crystals  

SciTech Connect

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., E-mail: smartlabindia@gmail.com; Lincy, A., E-mail: lincymaria@gmail.com; Mahalakshmi, V.; Saban, K. V. [Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College (India)] [Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College (India)

2013-01-15

248

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

249

Raman spectroscopic study of the antimonate mineral roméite  

NASA Astrophysics Data System (ADS)

Raman spectroscopy has been sued to study the antimony containing mineral roméite Ca 2Sb 2O 6(OH,F,O) from three different origins. Roméite is a calcium antimonate mineral of the pyrochlore group. An intense Raman band at ˜518 cm -1 for roméite is assigned to the SbO ? 1 symmetric stretching mode and the band at 466 cm -1 to the SbO ? 3 antisymmetric stretching mode. The Raman band at 303 cm -1 is attributed to the OSbO bending mode. Some variation in band positions is observed and is attributed to the variation in composition between the three mineral samples.

Bahfenne, Silmarilly; Frost, Ray L.

2010-02-01

250

Thermo-active polymer nanocomposites: a spectroscopic study  

NASA Astrophysics Data System (ADS)

Photo- and thermo-mechanical actuation behaviour in specific polymer-carbon nanotube composites has been observed in recent years and studied at the macroscale. These systems may prove to be suitable components for a wide range of applications, from MOEMs and nanotechnology to neuroscience and tissue engineering. Absence of a unified model for actuation behaviour at a molecular level is hindering development of such smart materials. We observed thermomechanical actuation of ethylene-vinyl acetate | carbon nanotube composites through in situ near-edge X-ray absorption fine structure spectroscopy to correlate spectral trends with macroscopic observations. This paper presents spectra of composites and constituents at room temperature to identify resonances in a building block model, followed by spectra acquired during thermo-actuation. Effects of strain-induced filler alignment are also addressed. Spectral resonances associated with C=C and C=O groups underwent synchronised intensity variations during excitation, and were used to propose a conformational model of actuation based on carbon nanotube torsion. Future actuation studies on other active polymer nanocomposites will verify the universality of the proposed model.

Winter, A. Douglas; Larios, Eduardo; Jaye, Cherno; Fischer, Daniel A.; Omastová, Mária; Campo, Eva M.

2014-09-01

251

Multinuclear nuclear magnetic resonance spectroscopic study of cartilage proteoglycans  

SciTech Connect

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

Lerner, L.

1985-01-01

252

An In-Depth Spectroscopic Analysis of RR Lyr Variations over the Pulsation Cycle  

E-print Network

The stellar parameters of RR Lyrae stars vary considerably over a pulsation cycle, and their determination is crucial for stellar modelling. We present a detailed spectroscopic analysis of the pulsating star RR Lyr, the prototype of its class, over a complete pulsation cycle, based on high-resolution spectra collected at the 2.7-m telescope of McDonald Observatory. We used simultaneous photometry to determine the accurate pulsation phase of each spectrum and determined the effective temperature, the shape of the depth-dependent microturbulent velocity, and the abundance of several elements, for each phase. The surface gravity was fixed to 2.4. Element abundances resulting from our analysis are stable over the pulsation cycle. However, a variation in ionisation equilibrium is observed around minimum radius. We attribute this mostly to a dynamical acceleration contributing to the surface gravity. Variable turbulent convection on time scales longer than the pulsation cycle has been proposed as a cause for the Bl...

Fossati, L; Shulyak, D V; Elmasli, A; Tsymbal, V; Barnes, T G; Guggenberger, E; Kochukhov, O

2014-01-01

253

IR-spectroscopic study of lewis acid centers on polyzirconiummethylsiloxanes  

NASA Astrophysics Data System (ADS)

Acid centers on the surface of polyzirconiummethylsiloxanes (PZMS) containing 5 and 10% ZrO2 were studied by diffuse-reflectance IR-spectroscopy. Deuterated acetonitrile adsorbed at room temperature at a 96 torr saturated vapor pressure was used as a probe-molecule for acid centers. It was shown that zirconium ions were not built into the matrix but were situated predominantly on the surface of the siliconoxygen framework of silica gels. The introduction of zirconium ions into the polymethylsiloxane matrix at the stage of sol formation caused the appearance of Lewis acid centers (coordinatively unsaturated zirconium ions) on the surface of PZMS along with centers of the physical adsorption of CD3CN.

Kustov, L. M.; Tkachenko, O. P.; Bondar', L. A.

2010-07-01

254

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

255

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

256

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

257

Acidic properties of sulfated zirconia: An infrared spectroscopic study  

SciTech Connect

Sulfated zirconia with S content of 2 wt.% equivalent to complete coverage of its surface was studied by infrared spectroscopy. At least four sulfated species were identified and exhibited an important and reversible sensitivity to water. These equilibria were demonstrated to exist by the study of adsorption of incremental amounts of water. D{sub 2}O and H{sub 2}{sup 18}O isotopically enriched water molecules were used to assist interpretation of IR spectra. To characterize acidity features, the probe molecules butane, CO, and H{sub 2}O (as weak bases) or pyridine (as a strong base) were adsorbed. Two Lewis acid sites (L{sub 1} and L{sub 2}) were observed and one Bronsted site (B) related to the zirconia support (L{sub 1}) and the sulfated species (L{sub 2}, B). They were evidenced by pyridine adsorption which was shown to partly displace adsorbed sulfate species. With the help of previous theoretical calculations using an ab initio method and representing the zirconia surface by a mononuclear zirconium complex, it is emphasized that the sulfated zirconia can be visualized as a H{sub 2}SO{sub 4} compound grafted onto the surface of zirconia in a way which makes it very sensitive to water but in a reversible way. Its acidity is similar to that of sulfuric acid but it is not really superacidic. Comparison with other oxides leads us to suggest that the cationic charge borne by the metallic cation is of prime importance for the acidity strength. The role of water on the acidic and catalytic properties for n-butane isomerization reaction is emphasized. 33 refs., 11 figs., 2 tabs.

Babou, F.; Coudurier, G.; Vedrine, J.C. [Institut de Recherches sur la Catalyse (CNRS), Villeurbanne (France)] [Institut de Recherches sur la Catalyse (CNRS), Villeurbanne (France)

1995-04-01

258

Defect study in ZnO related structures—A multi-spectroscopic approach  

Microsoft Academic Search

ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H2O2 pre-treatment induced ohmic

C. C. Ling; C. K. Cheung; Q. L. Gu; X. M. Dai; S. J. Xu; C. Y. Zhu; J. M. Luo; K. H. Tam; A. B. Djuriši?; C. D. Beling; S. Fung; L. W. Lu; G. Brauer; W. Anwand; W. Skorupa; H. C. Ong

2008-01-01

259

Gamma-ray resonance spectroscopic study of MoS 2 - and iron-based catalysts  

Microsoft Academic Search

1.A gamma-resonance spectroscopic study has been made of systems obtained by impregnating molybdenum disulfide samples with solutions of57Fe(NO3)3·9H2O in different solvents (formamide, acetone, water) and subsequently sulfidizing them. After a catalyst is sulfidized, most of the iron is in the form of magnetic sulfides, and the remainder is present in the form of the paramagnetic ions Fe2+ and Fe3+.2.The catalytic

R. A. Stukan; R. M. Bagirov; L. I. Nikulina; M. V. Landau; B. K. Nefedov; Yu. N. Novikov; M. E. Vol'pin

1988-01-01

260

Spectroscopic study of intermolecular complexes between FAD and some ?-carboline derivatives  

NASA Astrophysics Data System (ADS)

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

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

261

Spectroscopic study of dinitrophenol herbicide sorption on smectite.  

PubMed

Sorption of two dinitrophenolic herbicides, 4,6-dinitro-o-cresol (DNOC) and 4,6-dinitro-2-sec-butylphenol (DINOSEB) to smectite was studied using FTIR, HPLC, and quantum chemical methods. The high affinity of DNOC and DINOSEB for smectite surfaces was attributed to site-specific interactions with exchangeable cations and nonspecific van der Waals interactions with the siloxane surface. The positions of the nu(asym)(NO) and nu(sym)(NO) vibrational modes were perturbed by the exchangeable cations with similar changes occurring for both alkali and alkaline earth cations as a function of ionic potential. The cation-induced changes to the vibrational bands of the NO2 groups indicate that exchangeable metal cations are coordinated to -NO2 groups. Quantum chemical methods predicted a red-shift of the nu(asym)(NO) band and a corresponding blue-shift of the nu(sym)(NO) modes, as was observed experimentally. The nature of the smectite surface itself did not strongly influence the vibrational modes of sorbed DNOC or DINOSEB on the basis of a comparison of DNOC sorbed to three different smectites (K-SWy-2, K-SAz-1, and K-SHCa-1). FTIR spectra of DNOC and DINOSEB sorbed to a K-SWy-2 smectite were studied quantitatively using a modified form of Beers law. The FTIR-derived sorption isotherm of DNOC sorbed to K-SWy-2 was in good agreement with the isotherm derived from HPLC measurements. The molar absorptivity value of DNOC sorbed to K-SWy-2 smectite was 1.43 x 10(7) cm2/mol in good agreement with literature values for nitroaromatics (average value of 1.72 x 10(7) +/- 0.3 cm2/mol). On the basis of this value, the limit of detection using the FTIR method of approximately 5 microgDNOC g(clay) was determined. These two observations (sorption isotherms and molar absorptivity) provide a direct link between the macroscopic sorption results and the FTIR spectra. PMID:12523422

Johnston, C T; Sheng, G; Teppen, B J; Boyd, S A; de Oliveira, M F

2002-12-01

262

Photocurrent spectroscopic studies of diketopyrrolopyrrole-based statistical copolymers.  

PubMed

Diketopyrrolopyrrole (DPP) containing copolymers have gained a lot of interest in organic optoelectronics with great potential in organic photovoltaics. In this work, DPP based statistical copolymers, with slightly different bandgap energies and a varying fraction of donor-acceptor ratio are investigated using monochromatic photocurrent spectroscopy and Fourier-transform photocurrent spectroscopy (FTPS). The statistical copolymer with a lower DPP fraction, when blended with a fullerene derivative, shows the signature of an inter charge transfer complex state in photocurrent spectroscopy. Furthermore, the absorption spectrum of the blended sample with a lower DPP fraction is seen to change as a function of an external bias, qualitatively similar to the quantum confined Stark effect, from where we estimate the exciton binding energy. The statistical copolymer with a higher DPP fraction shows no signal of the inter charge transfer states and yields a higher external quantum efficiency in a photovoltaic structure. In order to gain insight into the origin of the observed charge transfer transitions, we present theoretical studies using density-functional theory and time-dependent density-functional theory for the two pristine DPP based statistical monomers. PMID:24452360

Moghe, Dhanashree; Dutta, Gitish K; Patil, Satish; Guha, Suchi

2014-03-01

263

[Preparation and spectroscopic studies of nanosilver/silk-fibroin composite].  

PubMed

The development of reliable, eco-friendly processes for the synthesis of nanomaterials is an important aspect of nanotechnology today. One approach that shows immense potential is based on the in situ synthesis of noble metal nanocolloids using natural biological material such as silk fibroin. In the present paper, the nano-Ag/silk-fibroin colloids were prepared by in situ reducing AgNO3 with silk-fibroin at room temperature without any reducing agent. UV-Vis absorption, atomic force microscopy, fluorescence spectra and resonance scattering spectra were used to study the preparation process and characterization of the nanocomposite. It was found that the formative Ag nanoparticles were attributed to the tyrosine residues in the chains of silk-fibroin that act as reduction agent in the reduction course of AgNO3, and the Ag nanoparticles were uniformly embedded in silk-fibroin colloid, which possess good dispersity and stability and can be kept for a long period. The strength of fluorescence spectra increased after reaction of silk-fibroin with AgNO3 solution, showing that there was a strong chemical adsorption between silver nanoparticles and silk-fibroin, and a stable complex layer was formed in silver nanoparticles. Meanwhile the existence of silver nanoparticles in silk-fibroin was proved by resonance scattering spectra. PMID:19093576

Ai, Shi-yun; Gao, Ji-gang; Zhu, Lu-sheng; Ma, Zhi-jun; Li, Xiao-chen

2008-09-01

264

IR absorption spectroscopic study of mixed cobalt substituted lithium ferrites  

NASA Astrophysics Data System (ADS)

The IR spectra of Li0.5-(x/2)CoxFe2.5-(x/2)O4 ferrite samples (0?x?0.6) prepared by solution combustion method have been reported. The influence of Co substitution is verified. XRD studies confirm the spinel phase formation of ferrites. Lattice constant varies linearly from 8.31 Å (x=0) to 8.35 Å (x=0.6) with composition. Evidence of two absorption bands in the IR spectra (below 800 cm-1) reveals the characteristic feature of spinel ferrite. The IR spectra featured additional three absorption bands around 550, 670 and 705 cm-1 for the samples x=0.1 and x=0.6. Absence of bands splitting specifies that Fe ions do not exist in excess form. It is found that high frequency band (?1), due to tetrahedral (A) group, lies at around 600 cm-1 and low frequency band (?2), due to octahedral (B) group, around 450 cm-1. The positions of bands are found to be composition dependent. The IR bands due to tetrahedral complexes shift slightly towards high frequency side with composition upto x=0.4 where as that due to octahedral complexes shift towards lower frequency side with x. Based on the data of absorption bands, force constants (kt, ko) and bond lengths (RA, RB) were estimated. Compositional dependence of force constants is explained on the basis of cation-oxygen bond distances of respective sites and cation distribution.

Sawant, V. S.; Bagade, A. A.; Mohite, S. V.; Rajpure, K. Y.

2014-10-01

265

An infrared and Raman spectroscopic study of the uranyl micas  

NASA Astrophysics Data System (ADS)

Vibrational spectroscopy using a combination of infrared and Raman spectroscopy has been used to study the uranyl micas also known as the autunite minerals, of general formula M(UO 2) 2(XO 4) 2·8-12H 2O where M may be Ba, Ca, Cu, Fe 2+, Mg, Mn 2+ or 1/2(HAl) and X is As or P. Included in these minerals are autunite, metautunite, torbernite, meta-torbernite, meta-zeunerite, saléeite and sabugalite. Compared with the results of infrared spectroscopy, Raman microscopy shows excellent band separation enabling the separation and identification of bands attributed to (UO 2) 2+ units, PO 4 and AsO 4 units. Common to all spectra were bands at around 900 and 818 cm -1, attributed to the antisymmetric and symmetric stretching vibrations of the (UO 2) 2+ units. Water in autunites is in a highly structured arrangement in the interlayer of the uranyl micas. Water molecules are differentiated according to the strength of the hydrogen bonds formed between the water and the adjacent uranyl-phosphate or uranyl-arsenate surfaces and the hydration sphere of the interlayer cation.

Frost, Ray L.

2004-06-01

266

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

267

Time-resolved photometric and spectroscopic analysis of a luminous Ap star HD103498  

E-print Network

We present the results on the photometric and spectroscopic monitoring of a luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using three-channel fast photometer attached to the 1.04-m optical telescope at ARIES, Nainital. The photometric data of five nights of year 2007 show clear signature of 15-min periodicity. However, the follow-up observations during 2007--2009 could not repeated any such periodicity. To confirm the photometric light variations, the time-series spectroscopic observations were carried out with the 2.56-m Nordic Optical Telescope (NOT) at La Palma on February 2, 2009. Any radial velocity variations were absent in this data set which is in full agreement with the photometric observations taken near the same night. Model atmosphere and abundance analysis of HD103498 show that the star is evolved from the Main Sequence and its atmospheric abundances are similar to two other evolved Ap stars HD133792 and HD204411: large overabundances of Si, Cr,...

Joshi, S; Kochukhov, O; Sachkov, M; Tiwari, S K; Chakradhari, N K; Piskunov, N

2009-01-01

268

Spectroscopic abundance analysis of dwarfs in young open cluster IC 4665  

E-print Network

We report a detailed spectroscopic abundance analysis for a sample of 18 F-K dwarfs of the young open cluster IC 4665. Stellar parameters and element abundances of Li, O, Mg, Si, Ca, Ti, Cr, Fe and Ni have been derived using the spectroscopic synthesis tool SME (Spectroscopy Made Easy). Within the measurement uncertainties the iron abundance is uniform with a standard deviation of 0.04 dex. No correlation is found between the iron abundance and the mass of the stellar convective zone, and between the Li abundance and the Fe abundance. In other words, our results do not reveal any signature of accretion and therefore do not support the scenario that stars with planets (SWPs) acquire their on the average higher metallicity compared to field stars via accretion of metal-rich planetary material. Instead the higher metallicity of SWPs may simply reflect the fact that planet formation is more efficient in high metallicity environs. However, since that many details of the planet system formation processes remain poo...

Shen, Z X; Lin, D N C; Liu, X W; Li, S L

2005-01-01

269

Raman spectroscopic study of G—A mismatches  

NASA Astrophysics Data System (ADS)

G—A mismatches are non-canonical base pairs that widely occur in native nucleic acids. They have been found to be functionally important in adopting unusual structures. In this paper, G—A mispairing was studied by Raman spectral characterization of Polyadenylic acid (PolyA), Polyguanylic acid (PolyG) and their equimolar mixture in solution of 0.08 mol/L Na+, pH7.0. The experiment showed the following three results. (1) At the experimental conditions used in the present work, PolyA and G—A complexes existed as single-stranded and double-stranded helix of A form, respectively. And PolyG mainly occurred to be anti-parallel quadruplex conformers. (2) The formation of G—A complexes, on one hand strengthened parts of base stacking interactions especially for PolyG, leading to Raman hypochromism effect with some corresponding bands shifting, and on the other hand weakened other base stacking interactions especially for PolyA to a certain degree. During this process, the backbone of PolyG underwent a significant change, but PolyA still conserved its main chain conformation. (3) The formation of G—A complexes was stabilized by two interbase hydrogen-bond interactions (i.e. N6H2(A)—N3 (G) and N7 (A)—N2H2(G)) and a third hydrogen bond between O2' (G) and N6 (A). The third hydrogen bond was responsible for the remarkable changes of PolyG backbone conformation.

Liao, Yu-Bo; Meng, Yao-Yong; Lei, Hao-Dong; Wang, Ying

2007-11-01

270

Applications of Linear Systems Theory to Spectroscopic Instrumentation and Multivariate Analysis  

NASA Astrophysics Data System (ADS)

This research employs linear systems theory to design novel spectroscopic instruments, explain their operation, and provide insight into methods of data analysis. The first study examines the relationship between digital filtering, a technique based on linear systems theory, and multivariate regression, a statistical method. The study focuses on quantitative property estimation for one -sided, repetitive, linear, shift-invariant systems, and compares matched filtering, Kalman innovation filtering, classical least-squares regression, and principal components regression. Kalman innovation filters, which are derived by making signals independent of interferences via orthogonalization, are similar to the respective columns of the pseudo-inverse of the pure signal matrix in classical least-squares regression, and to the regression vectors of principal components least -squares regression, which are derived via calibration. Inverse regression methods, such as principal components regression, are advantageous in that if the experiment is carefully designed, interferences need not be explicitly defined and properties that depend on multiple components can be estimated. In the second study, an absorption spectrophotometer based on a novel stationary interferometer is described. A major advantage of the interferometer is that it requires few optical components: minimally a slit, a collimator, a planar mirror, a magnification lens, and a photodiode array detector. The interferometer images a linear spatial interferogram on a photodiode array. Fourier transformation of the detected interferogram yields the desired spectrum. Equations describing interferometer operation are derived using electromagnetic wave theory and linear systems theory. Systems theory is also used to model and correct systematic errors. The interferometer's baseline noise, resolution, dynamic range and precision are assessed and compared to those of a modern grating-based photodiode-array spectrograph. Finally, the theory of grating-based optical spectrometers is explored using linear systems theory. This theory explains how diffraction gratings transform a polychromatic spectral input to an angularly-dependent output. Using the system transfer functions, a Fourier relationship is shown to exist between the wavenumber and spatial domains of the grating. This domain connectivity can be exploited to design diffraction gratings in the spatial domain that perform specific analytical tasks in the spectral domain.

Erickson, Chris L.

271

Radio-colouration of diamond: a spectroscopic study  

NASA Astrophysics Data System (ADS)

We have undertaken a study of the common green or orange-brown spots at the surface of rough diamond specimens, which are caused by alpha particles emanating from radioactive sources outside the diamond. Richly coloured haloes represent elevated levels of structural damage, indicated by strong broadening of the main Raman band of diamond, intense strain birefringence, and up-doming of spots due to their extensive volume expansion. Green radio-colouration was analogously generated through the irradiation of diamond with 8.8 MeV helium ions. The generation of readily visible radio-colouration was observed after irradiating diamond with ?1015 He ions per cm2. The accumulation of such a high number of alpha particles requires irradiation of the diamond from a radioactive source over long periods of time, presumably hundreds of millions of years in many cases. In the samples irradiated with He ions, amorphisation was observed in volume areas where the defect density exceeded 5 × 10-3 Å-3 (or 0.03 dpa; displacements per target atom). In contrast, graphitisation as a direct result of the ion irradiation was not observed. The green colouration transformed to brown at moderate annealing temperatures (here 450 °C). The colour transformation is associated with only partial recovery of the radiation damage. The colour change is mainly due to the destruction of the GR1 centre, explained by trapping of vacancies at A defects to form the H3 centre. An activation energy of ~2.4 ± 0.2 eV was determined for the GR1 reduction. The H3 centre, in turn, causes intense yellowish-green photoluminescence under ultraviolet illumination. Radio-colouration and associated H3 photoluminescence are due to point defects created by the ions irradiated, whereas lattice ionisation is of minor importance. This is concluded from the depth distribution of the colouration and the photoluminescence intensity (which corresponds to the defect density but not the ionisation distribution pattern). The effect of the implanted He ions themselves on the colour and photoluminescence seems to be negligible, as radio-colouration and H3 emission were analogously produced through irradiation of diamond with C ions. The photoluminescence emission becomes observable at extremely low defect densities on the order of 10-6 Å-3 (or 0.000006 dpa) and is suppressed at moderate defect densities of ~5 × 10-4 Å-3 (or ~0.003 dpa). Intensely brown-coloured diamond hence does not show the H3 emission anymore. Anneals up to 1,600 °C has reduced considerably irradiation damage and radio-colouration, but the structural reconstitution of the diamond (and its de-colouration) was still incomplete.

Nasdala, Lutz; Grambole, Dieter; Wildner, Manfred; Gigler, Alexander M.; Hainschwang, Thomas; Zaitsev, Alexander M.; Harris, Jeffrey W.; Milledge, Judith; Schulze, Daniel J.; Hofmeister, Wolfgang; Balmer, Walter A.

2013-05-01

272

Raman spectroscopic analysis of supersaturated aqueous solution of MgO·B 2O 3–32%MgCl 2–H 2O during acidification and dilution  

Microsoft Academic Search

Raman spectra of supersaturated aqueous solution of MgO·B2O3–32%MgCl2–H2O during acidification\\/alkalization and dilution have been studied. The assignments of the recorded Raman shift are given. The main existing forms of polyborate anions and their interaction in borate aqueous solution have been proposed through spectroscopic analysis. The experimental results indicate that the higher concentration of cation are beneficial not only to the

Liu Zhihong; Gao Bo; Li Shuni; Hu Mancheng; Xia Shuping

2004-01-01

273

Experimental (FT-IR, FT-Raman, UV and NMR) and quantum chemical studies on molecular structure, spectroscopic analysis, NLO, NBO and reactivity descriptors of 3,5-Difluoroaniline.  

PubMed

Comprehensive investigation of geometrical and electronic structure in ground as well as the first excited state of 3,5-Difluoroaniline (C6H5NF2) was carried out. The experimentally observed spectral data (FT-TR and FT-Raman) of the title compound was compared with the spectral data obtained by DFT/B3LYP method using 6-311++G(d,p) basis set. The molecular properties like dipole moment, polarizability, first static hyperpolarizability, molecular electrostatic potential surface (MEPs), and contour map were calculated to get a better insight of the properties of the title molecule. Natural bond orbital (NBO) analysis was applied to study stability of the molecule arising from charge delocalization. UV-Vis spectrum of the title compound was also recorded and the electronic properties, such as Frontier orbitals and band gap energies were measured by TD-DFT approach. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. Global and local reactivity descriptors were computed to predict reactivity and reactive sites on the molecule. (1)H and (13)C NMR spectra by using gauge including atomic orbital (GIAO) method of studied compound were compared with experimental data obtained. Moreover, the thermodynamic properties were evaluated. PMID:25078461

Pathak, S K; Srivastava, R; Sachan, A K; Prasad, O; Sinha, L; Asiri, A M; Karabacak, M

2015-01-25

274

An in-depth spectroscopic analysis of RR Lyr Variations over the pulsation cycle?  

NASA Astrophysics Data System (ADS)

The stellar parameters of RR Lyrae stars vary considerably over a pulsation cycle, and their determination is crucial for stellar modelling. We present a detailed spectroscopic analysis of the pulsating star RR Lyr, the prototype of its class, over a complete pulsation cycle, based on high-resolution spectra collected at the 2.7-m telescope of McDonald Observatory. We used simultaneous photometry to determine the accurate pulsation phase of each spectrum and determined the effective temperature, the shape of the depth-dependent microturbulent velocity, and the abundance of several elements, for each phase. The surface gravity was fixed to 2.4. Element abundances resulting from our analysis are stable over the pulsation cycle. However, a variation in ionization equilibrium is observed around minimum radius. We attribute this mostly to a dynamical acceleration contributing to the surface gravity. Variable turbulent convection on time-scales longer than the pulsation cycle has been proposed as a cause for the Blazhko effect. We test this hypothesis to some extent by using the derived variable depth-dependent microturbulent velocity profiles to estimate their effect on the stellar magnitude. These effects turn out to be wavelength dependent and much smaller than the observed light variations over the Blazhko cycle: if variations in the turbulent motions are entirely responsible for the Blazhko effect, they must surpass the scales covered by the microturbulent velocity. This work demonstrates the possibility of a self-consistent spectroscopic analysis over an entire pulsation cycle using static atmosphere models, provided one takes into account certain features of a rapidly pulsating atmosphere.

Fossati, L.; Kolenberg, K.; Shulyak, D. V.; Elmasli, A.; Tsymbal, V.; Barnes, T. G.; Guggenberger, E.; Kochukhov, O.

2014-12-01

275

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.

276

Comprehensive processing, display and analysis for in vivo MR spectroscopic imaging.  

PubMed

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 images and multiparametric and regional statistical analysis methods can improve detection of altered metabolite distributions. As a result, full MRSI processing and analysis can involve multiple processing steps and several different data types. In this paper, a processing environment is described that integrates and automates these data processing and analysis functions for imaging of proton metabolite distributions in the normal human brain. The capabilities include normalization of metabolite signal intensities and transformation into a common spatial reference frame, thereby allowing the formation of a database of MR-measured human metabolite values as a function of acquisition, spatial and subject parameters. This development is carried out under the MIDAS project (Metabolite Imaging and Data Analysis System), which provides an integrated set of MRI and MRSI processing functions. It is anticipated that further development and distribution of these capabilities will facilitate more widespread use of MRSI for diagnostic imaging, encourage the development of standardized MRSI acquisition, processing and analysis methods and enable improved mapping of metabolite distributions in the human brain. PMID:16763967

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

2006-06-01

277

Molecular orbital studies (hardness, chemical potential, electronegativity and electrophilicity), vibrational spectroscopic investigation and normal coordinate analysis of 5-{1-hydroxy-2-[(propan-2-yl)amino]ethyl}benzene-1,3-diol  

NASA Astrophysics Data System (ADS)

FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm-1 and 4000-100 cm-1 respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the ? antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of ? and ? electron (??DOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated.

Muthu, S.; Renuga, S.

2014-01-01

278

Molecular orbital studies (hardness, chemical potential, electronegativity and electrophilicity), vibrational spectroscopic investigation and normal coordinate analysis of 5-{1-hydroxy-2-[(propan-2-yl)amino]ethyl}benzene-1,3-diol.  

PubMed

FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm(-1) and 4000-100 cm(-1) respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the ? antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of ? and ? electron (??DOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated. PMID:24096064

Muthu, S; Renuga, S

2014-01-24

279

[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

280

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

NASA Astrophysics Data System (ADS)

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

Adeniyi, Adebayo A.; Ajibade, Peter A.

2013-11-01

281

Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses  

NASA Astrophysics Data System (ADS)

In this paper spectroscopic investigation of Cu2+ doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR - X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu2+ state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu2+ is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P-O-P bonds and creating more number of new P-O-Cu bonds.

Sastry, S. Sreehari; Rao, B. Rupa Venkateswara

2014-02-01

282

Synthesis, spectroscopic characterization of novel 16?-(3-acetyl phenyl amino)-3?-hydroxy pregn-5-ene-20-one, its molecular structure, NBO analysis, intramolecular interactions studied by DFT and AIM approach  

NASA Astrophysics Data System (ADS)

A novel compound 16?-(3-acetyl phenyl amino)-3?-hydroxy pregn-5-ene-20-one was synthesized by Michael addition reaction and characterized with the aid of 1H, 13C NMR, IR, UV and mass spectrometry. The molecular geometry of synthesized compound was calculated in the ground state by density functional theory (DFT/B3LYP) using 6-31G(d,p) basis set. 1H and 13C NMR chemical shifts were calculated using Gauge-Including Atomic Orbital (GIAO) approach and these values were correlated with the experimental observations. The electronic properties such as HOMO and LUMO energies were calculated using time dependent density functional theory (TD-DFT). Stability of the molecule as a result of hyperconjugative interactions and electron delocalization were analyzed using natural bond orbital (NBO) analysis. Intramolecular interactions were analyzed by AIM approach. Local reactivity descriptors were calculated to study the reactive site within the molecule.

Sethi, Arun; Shukla, Dolly; Singh, Ranvijay Pratap

2014-09-01

283

Detailed spectroscopic analysis of SN 1987A: The distance to the LMC using the SEAM method  

SciTech Connect

Supernova 1987A remains the most well-studied supernova to date. Observations produced excellent broad-band photometric and spectroscopic coverage over a wide wavelength range at all epochs. We model the observed spectra from Day 1 to Day 81 using a hydrodynamical model. We show that good agreement can be obtained at times up to about 60 days, if we allow for extended nickel mixing. Later than about 60 days the observed Balmer lines become stronger than our models can reproduce. We show that this is likely due to a more complicated distribution of gamma-rays than we allow for in our spherically symmetric calculations. We present synthetic light curves in UBVRIJHK and a synthetic bolometric light curve. Using this broad baseline of detailed spectroscopic models we find a distance modulus mu = 18.5 +/- 0.2 using the SEAM method of determining distances to supernovae. We find that the explosion time agrees with that of the neutrino burst and is constrained at 68 percent confidence to within +/- 0.9 days. We argue that the weak Balmer lines of our detailed model calculations casts doubt on the accuracy of the purely photometric EPM method. We also suggest that Type IIP supernovae will be most useful as distance indicators at early times due to a variety of effects.

Mitchell, Robert C.; Baron, E.; Branch, David; Hauschildt, Peter H.; Nugent, Peter E.; Lundqvist, Peter; Blinnikov, Sergei; Pun, Chun S.J.

2002-05-21

284

Molecular structure, vibrational spectroscopic, first hyperpolarizability, NBO and HOMO, LUMO studies of P-Iodobenzene sulfonyl chloride  

Microsoft Academic Search

In this work, the experimental and theoretical vibrational spectra of P-Iodobenzene sulfonyl chloride (P-IBSC) were studied. P-IBSC and its derivatives present in many biologically active compounds. Because of their spectroscopic properties and chemical significance in particular, sulfonyl chloride and its derivatives have been studied extensively by spectroscopic (FTIR and FT-Raman spectra) and theoretical methods. The infrared spectra of these compounds

M. Arivazhagan; S. Prabhakaran; R. Gayathri

2011-01-01

285

Study of the effect of CalRed on the secondary structure of human serum albumin by spectroscopic techniques  

Microsoft Academic Search

The effect of Cal-Red on the structure of human serum albumin (HSA) was studied using Resonance light scattering (RLS), Fourier transformed Infrared (FT-IR) and Circular dichroism (CD) spectroscopic methods. The RLS spectroscopic results show that the RLS intensity of HSA was significantly increased in the presence of Cal-Red. The binding parameters of HSA with Cal-Red were studied at different temperatures

Lijun Dong; Xingguo Chen; Zhide Hu

2007-01-01

286

11998 Biochemistry 1995,34, 11998-12004 NMR Spectroscopic Analysis of the DNA Conformation Induced by the Human  

E-print Network

that partial intercalation of a protein side chain occurs between two adenine bases in the DNA octamer11998 Biochemistry 1995,34, 11998- 12004 NMR Spectroscopic Analysis of the DNA Conformation Induced Manuscript Received July 18, 1995@ ABSTRACT: The conformation of an eight base pair DNA oligonucleotide

Clore, G. Marius

287

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

288

Spectroscopic and Structural Study of Proton and Halide Ion Cooperative Binding to GFP  

PubMed Central

This study reports the influence of halogens on fluorescence properties of the Aequorea victoria Green Fluorescent Protein variant S65T/T203Y (E2GFP). Halide binding forms a specific nonfluorescent complex generating a substantial drop of the fluorescence via static quenching. Spectroscopic analysis under different solution conditions reveals high halogen affinity, which is strongly dependent on the pH. This evidences the presence in E2GFP of interacting binding sites for halide ions and for protons. Thermodynamic link and cooperative interaction are assessed demonstrating that binding of one halide ion is associated with the binding of one proton in a cooperative fashion with the formation, in the pH range 4.5–10, of a single fully protonated E2GFP·halogen complex. To resolve the structural determinants of E2GFP sensitivity to halogens, high-resolution crystallographic structures were obtained for the halide-free and I?, Br?, and Cl? bound E2GFP. Remarkably the first high-resolution (1.4 Å) crystallographic structure of a chloride-bound GFP is reported. The chloride ion occupies a specific and unique binding pocket in direct contact (3.4 Å) with the chromophore imidazolidinone aromatic ring. Unanticipated flexibility, strongly modulated by halide ion interactions, is observed in the region surrounding the chromophore. Furthermore molecular dynamics simulations identified E222 residue (along with the chromophore Y66 residue) being in the protonated state when E2GFP·halogen complex is formed. The impact of these results on high-sensitivity biosensor design will be discussed. PMID:17434942

Arosio, Daniele; Garau, Gianpiero; Ricci, Fernanda; Marchetti, Laura; Bizzarri, Ranieri; Nifosi, Riccardo; Beltram, Fabio

2007-01-01

289

Solvation and protonation of coumarin 102 in aqueous media: a fluorescence spectroscopic and theoretical study.  

PubMed

The ground- and excited-state protonation of Coumarin 102 (C102), a fluorescent probe applied frequently in heterogeneous systems with an aqueous phase, has been studied in aqueous solutions by spectroscopic experiments and theoretical calculations. For the dissociation constant of the protonated form in the ground state, pKa = 1.61 was obtained from the absorption spectra; for the excited-state dissociation constant, pKa* = 2.19 was obtained from the fluorescence spectra. These values were closely reproduced by theoretical calculations via a thermodynamic cycle (the value of pKa* also by calculations via the Förster cycle) using an implicit–explicit solvation model (polarized continuum model + addition of a solvent molecule). The theoretical calculations indicated that (i) in the ground state, C102 occurs primarily as a hydrogen-bonded water complex, with the oxo group as the binding site, (ii) this hydrogen bond becomes stronger upon excitation, and (iii) in the ground state, the amino nitrogen atom is the protonation site, and in the excited state, the carboxy oxygen atom is the protonation site. A comprehensive analysis of fluorescence decay data yielded the values kpr = 3.27 × 10(10) M(–1) s(–1) for the rate constant of the excited-state protonation and kdpr = 2.78 × 10(8) s(–1) for the rate constant of the reverse process (kpr and kdpr were treated as independent parameters). This, considering the relatively long fluorescence lifetimes of neutral C102 (6.02 ns) and its protonated form (3.06 ns) in aqueous media, means that a quasi-equilibrium state of excited-state proton transfer is reached in strongly acidic solutions. PMID:24945906

Hessz, Dóra; Hégely, Bence; Kállay, Mihály; Vidóczy, Tamás; Kubinyi, Miklós

2014-07-17

290

Development of monoclonal antibodies to 4-hydroxyestrogen-2-N-acetylcysteine conjugates: immunoaffinity and spectroscopic studies.  

PubMed

Catechol estrogen quinones (CEQ) derived from oxidation of the catechol estrogens 4-hydroxyestrone (4-OHE1) and 4-hydroxyestradiol (4-OHE2) can conjugate with glutathione (GSH), a reaction that prevents damage to DNA and can provide biomarkers of exposure to CEQs. Monoclonal antibodies (MAb) to 4-OHE1(E2)-2-N-acetylcysteine [4-OHE1(E2)-2-NAcCys] were developed and characterized by immunological and spectroscopic studies. The NAcCys conjugate is the hydrolytic product of the corresponding conjugate with GSH, followed by N-acetylation of cysteine. MAbs were produced by immunizing mice with 4-OHE1(E2)-2-NAcCys attached to an appropriate linker that was conjugated to keyhole limpet hemocyanin (KLH). Hybridoma cell lines were screened using 4-OHE1(E2)-2-NAcCys conjugated to ovalbumin (OA). There is no immunological cross-reactivity between KLH and OA. Hence, positive hybridoma cell lines secreting antibody against 4-OHE1(E2)-2-NAcCys could be rapidly identified using OA-4-OHE1(E2)-2-NAcCys. An affinity column was developed and used to purify MAb against 4-OHE1(E2)-2-NAcCys. The purified MAb was immobilized on an agarose bead column. This column was used to capture and preconcentrate the hapten of interest out of urine samples. A number of structurally related standards were used to estimate the selectivity and specificity of the chosen MAb. Capillary electrophoresis (CE) with field-amplified sample stacking in absorbance detection mode and laser-induced low temperature luminescence measurements were used to identify and quantitate the 4-OHE1(E2)-2-NAcCys conjugates and related compounds released from the affinity column. Femtomole detection limits have been demonstrated. Future prospects in clinical diagnostics for testing human exposure to CEQ by urine analysis are briefly addressed. PMID:16533015

Markushin, Y; Kapke, P; Saeed, M; Zhang, H; Dawoud, A; Rogan, E G; Cavalieri, E L; Jankowiak, R

2005-10-01

291

Spectroscopic Analysis of First Experiments of Al Planar Foils and Single Planar Wire Arrays on Zebra at UNR*  

NASA Astrophysics Data System (ADS)

A spectroscopic analysis of experiments with Al planar foils and single planar wire arrays (SPWA) performed on the Zebra generator is presented. Both types of experiments were performed at standard (1.0MA) and enhanced (1.7MA) currents each with the required masses to attain implosion close to peak current. As a general trend, the loads performed at enhanced current are shown to have nearly double the energy output than loads performed at standard current. Data from a full diagnostic set was analyzed with major focus on x-ray spectroscopic data. A non-LTE kinetic model was used to derive plasma parameters of electron temperature and density and estimate opacity effects. Similarities and differences in K-shell spectroscopic features radiated from Al foils and SPWAs are identified and discussed.

Zunino, H. A.; Weller, M. E.; Stafford, A.; Safronova, A. S.; Kantsyrev, V. I.; Chuvatin, A. S.; Shrestha, I.; Osborne, G. C.; Shlyaptseva, V. V.; Keim, S. F.

2011-11-01

292

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

NASA Astrophysics Data System (ADS)

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

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

1993-06-01

293

Spectroscopic investigation (FT-IR and FT-Raman), vibrational assignments, HOMO-LUMO analysis and molecular docking study of 2-(Adamantan-1-yl)-5-(4-nitrophenyl)-1,3,4-oxadiazole.  

PubMed

FT-IR and FT-Raman spectra of 2-(Adamantan-1-yl)-5-(4-nitrophenyl)-1,3,4-oxadiazole were recorded and analyzed. The vibrational wavenumbers were computed using DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign vibrational bands obtained experimentally. The energy barriers of the internal rotations about the CC bonds connecting the oxadiazole to the adamantane and benzene rings are reported. The geometrical parameters (DFT) of the title compound are in agreement with the XRD results. The calculated HOMO and LUMO energies allow the calculations of atomic and molecular properties and they also showed that charge transfer occurs in the molecule. A detailed molecular picture of the title compound and its interactions were obtained from NBO analysis. As can be seen from the MEP map of the title compound, which regions having the negative potential are over the electro negative atoms, the region having the positive potential are over the phenyl and adamantine rings and the remaining species are surrounded by zero potential. The molecular docking studies reveal that the adamantyl derivative may exhibit C-South African HIV-proteas inhibitory activity. PMID:25168235

Haress, Nadia G; Al-Omary, Fatmah; El-Emam, Ali A; Mary, Y Sheena; Panicker, C Yohannan; Al-Saadi, Abdulaziz A; War, Javeed Ahmad; Van Alsenoy, Christian

2015-01-25

294

The Penn State-Toru? Centre for Astronomy Planet Search stars. I. Spectroscopic analysis of 348 red giants  

NASA Astrophysics Data System (ADS)

Aims: We present basic atmospheric parameters (Teff, log g, vt, and [Fe/H]) as well as luminosities, masses, radii, and absolute radial velocities for 348 stars, presumably giants, from the ~1000 star sample observed within the Penn State-Toru? Centre for Astronomy Planet Search with the High Resolution Spectrograph of the 9.2 m Hobby-Eberly Telescope. The stellar parameters (luminosities, masses, radii) are key to properly interpreting newly discovered low-mass companions, while a systematic study of the complete sample will create a basis for future statistical considerations concerning the appearance of low-mass companions around evolved low- and intermediate-mass stars. Methods: The atmospheric parameters were derived using a strictly spectroscopic method based on the LTE analysis of equivalent widths of Fe I and Fe II lines. With existing photometric data and the Hipparcos parallaxes, we estimated stellar masses and ages via evolutionary tracks fitting. The stellar radii were calculated from either estimated masses and the spectroscopic log g or from the spectroscopic Teff and estimated luminosities. The absolute radial velocities were obtained by cross-correlating spectra with a numerical template. Results: We completed the spectroscopic analysis for 332 stars, 327 of which were found to be giants. A simplified analysis was applied to the remaining 16 stars, which had incomplete data. The results show that our sample is composed of stars with effective temperatures ranging from 4055 K to 6239 K, with log g between 1.39 and 4.78 (5 dwarfs were identified). The estimated luminosities are between log L/L? = -1.0 and 3 and lead to masses ranging from 0.6 to 3.4 M?. Only 63 stars with masses larger than 2 M? were found. The radii of our stars range from 0.6 to 52 R? with the vast majority between 9-11 R?. The stars in our sample are generally less metal-abundant than the Sun with median [Fe/H] = -0.15. The estimated uncertainties in the atmospheric parameters were found to be comparable to those reached in other studies. However, due to lack of precise parallaxes, the stellar luminosities and, in turn, the masses are far less precise, within 0.2 M? in best cases and 0.3 M? on average. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.Tables 1 and 5 are only available at the 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/547/A91

Zieli?ski, P.; Niedzielski, A.; Wolszczan, A.; Adamów, M.; Nowak, G.

2012-11-01

295

Spectroscopic ellipsometry analysis of a thin film composite membrane consisting of polysulfone on a porous ?-alumina support.  

PubMed

Exposure of a thin polymer film to a fluid can affect properties of the film such as the density and thickness. In particular in membrane technology, these changes can have important implications for membrane performance. Spectroscopic ellipsometry is a convenient technique for in situ studies of thin films, because of its noninvasive character and very high precision. The applicability of spectroscopic ellipsometry is usually limited to samples with well-defined interfacial regions, whereas in typical composite membranes, often substantial and irregular intrusion of the thin film into the pores of a support exists. In this work, we provide a detailed characterization of a polished porous alumina membrane support, using variable-angle spectroscopic ellipsometry in combination with atomic force microscopy and mercury porosimetry. Two Spectroscopic ellipsometry optical models are presented that can adequately describe the surface roughness of the support. These models consider the surface roughness as a distinct layer in which the porosity gradually increases toward the outer ambient interface. The first model considers the porosity profile to be linear; the second model assumes an exponential profile. It is shown that the models can be extended to account for a composite membrane geometry, by deposition of a thin polysulfone film onto the support. The developed method facilitates practicability for in situ spectroscopic ellipsometry studies of nonequilibrium systems, i.e., membranes under actual permeation conditions. PMID:22235899

Ogieglo, Wojciech; Wormeester, Herbert; Wessling, Matthias; Benes, Nieck E

2012-02-01

296

Spectroscopic Analysis of the Double Lined Eclipsing Binary {\\alpha}Vir  

E-print Network

{\\alpha}Vir is a well known double-lined spectroscopic binary with a B-type for both components. In the present paper we have analyzed a total of 90 spectra obtained through 1992-2000. Spectral analysis are based on two spectral lines H(alpha) and HeI 6678 belong to H(alpha) region. Radial velocity analysis have suggested low eccentric orbit (e=0.002) at inclination (i=81.89+-2.34) and with 4d.01422 period, semi-amplitude k1=100 km/s, mass ratio q=0.49+-0.05 and mass function f(m) =0.547. Using KOREL program for spectrum disentangling we have been able to decompose the spectrum of the system to its primary and secondary components. Synthetic spectral analysis of both the individual and disentangled spectra has been performed and yielded effective temperatures Teff= 25000+-250 K, surface gravities log g=3.75+-0.25 and projected rotational velocities (v sin i= 180+-5 km/s) for the primary, while for the secondary they are Teff = 17000+-250 K, log g = 4.0+-0.25.

Nouh, M I; Zaid, I; Elkhateeb, M M; Elkholy, E

2014-01-01

297

Spectroscopic study on the interaction of ct-DNA with manganese Salen complex containing triphenyl phosphonium groups.  

PubMed

The DNA binding properties of a bulky and hydrophobic Schiff base complex of manganese(III) [N,N'-bis(5-(triphenyl phosphonium methyl)salicylidene)-1,2-ethylene diamine chloride Mn(III) acetate] was examined by spectroscopic techniques. UV-vis titration data indicate both hypo and hyperchromic effect with addition of DNA to complex. A competitive binding study showed that the enhanced emission intensity of ethidium bromide (EB) in the presence of DNA was quenched by adding Mn Salen complex. This finding indicates that Mn Salen complex displaces EB from its binding site in DNA. Helix melting studies indicate improvement in the helix stability, and an increase in the melting temperature. The analysis of CD spectra represents the structural changes in DNA due to the binding of Mn Salen complex. The binding constant has been calculated using absorbance and fluorescence data. The results also represent that the binding process proceeds by strong electrostatic and hydrophobic interactions. PMID:22306451

Dehkordi, Maryam Nejat; Bordbar, Abdol-Khalegh; Lincoln, Per; Mirkhani, Valiollah

2012-05-01

298

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

299

The Synthesis, Characterization, Spectroscopic Studies and Catalyst Properties of Some New Dinuclear Uranyl (VI) Metal Complexes Bearing Different vic?Dioxime Groups  

Microsoft Academic Search

The synthesis, characterization and spectroscopic studies of some new dinuclear uranyl (VI) metal complexes prepared from different vic?dioximes ligands and the uranyl acetate metal salt. The structure of these uranyl (VI) metal complexes have been determined as according to elemental analysis, H?NMR spectra, FT?IR spectra, UV?Vis spectra, magnetic susceptibility measurements, melting point and molar conductivity measurements. The metal to ligand

A. Kilic; E. Tas

2007-01-01

300

Laser Raman spectroscopic study of water in gelatin–surfactant solutions and gels  

Microsoft Academic Search

A Raman spectroscopic study was carried out on water in gelatin at 4% w\\/v in gel (25?°C) and sol (40–60?°C) states at various\\u000a concentrations (0.5, 1, 5, 10 and 15?mM) of anionic surfactant, sodium dodecyl sulfate (SDS). The in-phase collective stretching\\u000a mode vibration of hydrogen-bonded -OH oscillators, centered around 3250?cm?1 in a tetrahedral network of water molecules, was observed to

S. Maity; S. S. Jena; A. Pradhan; H. B. Bohidar

1999-01-01

301

Fe-complex of a tetraamido macrocyclic ligand: Spectroscopic characterization and catalytic oxidation studies  

Microsoft Academic Search

This work presents the spectroscopic characterization and reaction studies of a FeIII-complex (2) of a tetraamido macrocyclic ligand (1, 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[a,g]cyclotridecene-6,7,14,16-tetraone). 2 was characterized primarily by means of EPR. In agreement with the magnetic moment (?eff=3.87 BM), EPR spectroscopy of 2 shows signals consistent with S=3\\/2 intermediate-spin ferric-iron. Besides EPR, mass spectrometry, UV\\/vis spectroscopy and cyclic voltammetry were used to further

Shane Z. Sullivan; Anindya Ghosh; Alexandru S. Biris; Sharon Pulla; Anna M. Brezden; Samulel L. Collom; Ross M. Woods; Pradip Munshi; Laura Schnackenberg; Brad S. Pierce; Ganesh K. Kannarpady

2010-01-01

302

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

303

Spectroscopic study of the light-harvesting protein C-phycocyanin associated with colorless linker peptides  

SciTech Connect

The phycobilisome (PBS) light-harvesting antenna is composed of chromophore-containing biliproteins and 'colorless' linker peptides and is structurally designed to support unidirectional transfer of excitation energy from the periphery of the PBS to its core. The linker peptides have a unique role in this transfer process by modulating the spectral properties of the associated biliprotein. There is only one three-dimensional structure of a biliprotein/linker complex available to date (APC/LC7.8) and the mechanism of interaction between these two proteins remains unknown. This study brings together a detailed spectroscopic characterization of C-Phycocyanin (PC)-linker complexes (isolated from Synechococcus sp. PCC 7002) with proteomic analysis of the linker amino acid sequences to produce a model for biliprotein/linker interaction. The amino acid sequences of the rod linkers [LR8.9, LR32.3 and LRC28.5] were examined to identify evolutionarily conserved regions important to either the structure or function of this protein family. Although there is not one common homologous site among all the linkers, there are strong trends across each separate subset (LC, LR and LRC) and the N-terminal segments of both LR32.3 and LRC28.5 display multiple regions of similarity with other linkers. Predictions of the secondary structure of LR32.3 and LRC28.5, and comparison to the crystal structure of LC7.8, further narrowed the candidates for interaction sites with the PC chromophores. Measurements of the absorption, fluorescence, CD and excitation anisotropy of PC trimer, PC/LR32.3, and PC/LRC28.5, document the spectroscopic effect of each linker peptide on the PC chromophores at a series of temperatures (298 to 77 K). Because LR32.3 and LRC28.5 modulate the PC trimer spectral properties in distinct manners, it suggests different chromophore-interaction mechanisms for each linker. The low temperature absorbance spectrum of the PC trimer is consistent with an excitonic coupling interaction between neighboring a84 and b84 chromophores. Association with LR32.3 does not greatly alter this band shape but the absorbance of the PC/LRC28.5 complex is dramatically different. This indicates that LRC28.5 is disrupting the a84 - b84 relation established in the PC trimer. From these, and other polarized spectroscopy measurements, we conclude that both LR32.3 and LRC28.5 affect the spectral properties of the terminally emitting PC trimer chromophore (b84), and that LRC28.5 is additionally perturbing the relationship between the a84 and b84 chromophores to either disrupt or enhance their coupling interaction. The linker can perturb the PC chromophores through either specific aromatic residues or a concentration of electrostatically charged residues. Structurally, the linker disrupts the C3 symmetry of the associated biliprotein and this asymmetric interaction can serve to guide the transfer of excitation energy in one direction.

Pizarro, Shelly A.

2000-05-12

304

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

305

Electrode materials for lithium rechargeable batteries: Synthesis, spectroscopic studies and electrochemical performance  

NASA Astrophysics Data System (ADS)

The lithium rechargeable battery is the newest member of the rechargeable battery family and is best known for its high energy density, long battery life, low self-discharge rate and light weight. This battery may become one of the most important energy sources in consumer market, industrial and military applications. Intercalation compounds play a critical role in determining the overall performance of a lithium rechargeable battery. The common intercalation materials for battery applications are layered structure Lisb{x}CoOsb2, spinel Lisb{x}Mnsb2Osb4 and lithium vanadium oxides, Lisb{x}Vsb2Osb5 and Lisb{x}Vsb3Osb8. Three distinct Lisb{x}Vsb2Osb5 phases, delta,\\ varepsilon, and gamma-Lisb{x}Vsb2Osb5, were obtained through a chemical intercalation reaction and solid state reactions. Infrared and Raman spectra were recorded for the three phases. The spectral changes were interpreted in terms of the local structural changes of the vanadium-oxygen polyhedra. Although the delta and varepsilon phases have very similar powder x-ray diffraction patterns, IR and Raman studies showed these two phases adopt distinctive local structural environments. These results demonstrate that IR and Raman spectroscopy are important techniques for the structural analysis of intercalation materials. Single crystals of Lisb{1.1}Vsb3Osb8 and sp6Lisb{1.1}Vsb3Osb8 were prepared using solid state synthesis techniques. IR spectra and polarized Raman spectra were recorded on the Lisb{1.1}Vsb3Osb8 and sp6Lisb{1.1}Vsb3Osb8 crystals and a lithiated phase, Lisb4Vsb3Osb8. Factor group analysis method was used to interpret the spectral changes. These spectroscopic results provide insight into the structural modifications originating from lithium intercalation/deintercalation processes. In situ Raman spectra of Lisb{x}Vsb2Osb5 were successfully recorded on a operating lithium rechargeable battery. Distinctive spectral changes were observed at different lithium intercalation levels and interpreted in terms of the slight rearrangements of the V-O structural units. The results show that in situ Raman spectroscopy may become an important nondestructive technique in investigating the irreversible structural changes in electrode materials and evaluating battery performance. For the first time novel mesostructural materials were synthesized as electrode materials for the lithium rechargeable battery. The well-ordered mesostructural materials provide an ideal host for lithium transport processes. The preliminary results on the manganese oxide-based cathode and tin oxide-based anode show that the templating synthesis technique may provide important electrode materials for battery applications.

Zhang, Xulong

306

Spectroscopic studies on the interaction between novel polyvinylthiol-functionalized silver nanoparticles with lysozyme.  

PubMed

Silver nanoparticles were functionalized with polyvinylthiol (Ag-PVT) and their effect on the conformation of hen-egg white lysozyme was seen by means of spectroscopic techniques, viz., UV visible, fluorescence (intrinsic and synchronous), resonance Rayleigh scattering and circular dichroism. UV absorption spectra of lysozyme show a hyperchromic shift on the addition of Ag-PVT nanoparticles indicating the complex formation between the two. The interaction between lysozyme and Ag-PVT nanoparticles was takes place via static quenching with 1:1 binding ratio as revealed by the analysis of fluorescence measurements. Circular dichroism spectroscopic data show a decrease in ?-helical content of lysozyme on interaction with Ag-PVT nanoparticles which was due to the partial unfolding of the protein. Synchronous fluorescence spectroscopy disclosed that the microenvironments of both tryptophan and tyrosine residues were perturbed in the presence of Ag-PVT nanoparticles and perturbation in the tryptophan environment was more prominent. Rayleigh scattering (RRS) intensity increases on increasing the Ag-PVT nanoparticles concentration till it reaches to the saturation. The RRS intensity increases four times as compared to the native protein indicating the possibility of protein aggregation at higher concentrations of nanoparticles. PMID:25062060

Ali, Mohd Sajid; Al-Lohedan, Hamad A; Rafiquee, M Z A; Atta, Ayman M; Ezzat, Abdurrahman O

2015-01-25

307

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

308

Spectroscopic pilot study in the near infrared of a sample of star-forming galaxies at z = 2  

NASA Astrophysics Data System (ADS)

In this work we present the results of the spectroscopic analysis inthe near-infrared K band of a sample of 12 active star forminggalaxies at z ˜ 2. The sample was selected by using photometricredshifts, blue colors and large fluxes in the 24 ? m band ofMIPS/Spitzer. To analyze their physical properties we have computedtheir sizes, colors, stellar masses, extinctions and other parametersavailable in literature and in the "Rainbow" database. We computeH? luminosities and star formation rates for all galaxies atthat redshift. We were able to estimate metallicities from [NII]6584for a sub sample of the objects. In particular the dependence of the metallicitywith the stellar mass has been studied and compared with the results of other samples ofgalaxies at several redshifts. For a fixed mass, the metallicities ofour galaxies are compatible than those similar at the corresponding redshift, following the general trend of lower metallicities for higher redshifts.

Gallego, J.; Sánchez de Miguel, A.; Zamorano, J.; Pérez-González, P. G.; Cardiel, N.; Barro, G.

2011-11-01

309

Synthesis, spectroscopic characterization, potentiometric studies, cytotoxic studies and molecular docking studies of DNA binding of transition metal complexes with 1,1-diaminopropane-Schiff base  

NASA Astrophysics Data System (ADS)

A new series of Schiff base transition metal complexes with N,N'-bis(2-hydroxybenzylidene)-1,1-diaminopropane (H2BHBDAP) have been prepared and characterized by elemental analysis, spectroscopic and magnetic measurements. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 °C and ionic strength 0.10 M sodium perchlorate. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. Additionally in silico, the Docking studies and the calculated pharmacokinetic parameters show promising futures for application of the ligand and complexes as high potency agents for DNA binding activity.

Alaghaz, Abdel-Nasser M. A.; El-Sayed, Badr A.; El-Henawy, Ahmed A.; Ammar, Reda A. A.

2013-03-01

310

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

311

Quantum mechanical study of the structure and spectroscopic (FT-IR, FT-Raman), first-order hyperpolarizability, NBO and HOMO-LUMO analysis of S-S-2 methylamino-1-phenyl propan-1-ol  

NASA Astrophysics Data System (ADS)

The experimental and theoretical vibrational spectra of S-S-2 methylamino-1-phenyl propan-1-ol (SSMPL). Fourier transform infrared (FTIR) and FT Raman spectra of SSMPL in the solid phase were recorded and analyzed. The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges were calculated using density functional theory calculation (B3LYP) with standard 6-31G(d,p) and high level 6-311++G(d,p) basis sets. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT Raman data. The thermodynamic functions of the title compound were also performed by B3LYP with two basis sets 6-31G(d,p) and 6-311++G(d,p). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Using the method B3LYP, the dipole moment (?), polarizability (?) and the hyperpolarizability (?) values of the investigated molecule has been computed. Total energy distribution (TED) was used for the assignment of Unambiguous vibrational fundamental modes. Finally, Simulated FTIR and FT Raman spectra of SSMPL showed good agreement with the observed spectra.

Ramachandran, G.; Muthu, S.; Renuga, S.

2013-04-01

312

Spectroscopic, reactivity and NLO analysis of new hydrazone-containing dipyrromethane using experimental and theoretical approaches  

NASA Astrophysics Data System (ADS)

The molecular structure and detailed spectroscopic analysis of a novel synthesized dipyrromethane: 1,9-bis[(2-hydroxybenzoyl)-hydrazonomethyl]-5-(2-nitrophenyl)-dipyrromethane (3) have been performed using both experimental techniques and theoretical calculations. Thermodynamic parameters (H, G, S) of reactants and products have been used to investigate the nature of synthesis. The singlet chemical shift at 5.343 ppm of meso-proton designates formation of product molecule (3). TD-DFT has been used to calculate oscillatory strength (f) and wavelength absorption maxima (?max) of various electronic excitations and their nature within molecule. The molecular orbital coefficients and molecular plots analysis assign nature of electronic excitations as ? ? ?*. Natural bond orbital (NBO) analysis has been carried out to investigate the intramolecular H-bonding, conjugative and hyperconjugative interactions within molecule. The result of intramolecular hydrogen bonding (O68sbnd H69⋯O22/O66sbnd H67⋯O45) is obvious in 1H NMR, FT-IR and NBO due to down field chemical shift, vibrational red shift, and n2(O22) ? ?*(O68sbnd H69)/n2(O45) ? ?*(O66sbnd H67) interactions energies 105.12/104.91 (kJ/mol), respectively. To investigate the strength and nature of H-bonding, topological parameters at bond critical points (BCP) have been analyzed by ‘Quantum theory of Atoms in molecules’ (QTAIM). Local reactivity descriptors- Fukui functions(fk+,fk-), local softnesses (sk+,sk-) and electrophilicity indices (?k+,?k-) analyses have been performed to find out the reactive sites of the molecule. The computed first hyperpolarizability (?0 = 14.30 × 10-30 esu) evaluates the molecule to be suitable for non-linear optical (NLO) response.

Singh, R. N.; Rawat, Poonat; Kumar, Amit

2014-06-01

313

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

314

Spectral analysis of tissues from patients with cancer using a portable spectroscopic diagnostic ratiometer unit  

NASA Astrophysics Data System (ADS)

Spectral profiles of tissues from patients with breast carcinoma, malignant carcinoid and non-small cell lung carcinoma were acquired using native fluorescence spectroscopy. A novel spectroscopic ratiometer device (S3-LED) with selective excitation wavelengths at 280 nm and 335 nm was used to produce the emission spectra of the key biomolecules, tryptophan and NADH, in the tissue samples. In each of the samples, analysis of emission intensity peaks from biomolecules showed increased 340 nm/440 nm and 340 nm/460 nm ratios in the malignant samples compared to their paired normal samples. This most likely represented increased tryptophan to NADH ratios in the malignant tissue samples compared to their paired normal samples. Among the non-small cell lung carcinoma and breast carcinomas, it appeared that tumors of very large size or poor differentiation had an even greater increase in the 340 nm/440 nm and 340 nm/460 nm ratios. In the samples of malignant carcinoid, which is known to be a highly metabolically active tumor, a marked increase in these ratios was also seen.

Sordillo, Laura A.; Pu, Yang; Sordillo, Peter P.; Budansky, Yury; Alfano, R. R.

2014-05-01

315

Raman spectroscopic analysis of a tembeté: a resin archaeological artefact in need of conservation  

NASA Astrophysics Data System (ADS)

The Raman spectroscopic analysis of a Brazilian tembetá, a lip-plug which signifies the attainment of manhood in tribal cultures, and dated to about 1600 years BP is reported. Tembetá are usually made of wood or stone but this lip-plug is very rare in that it is made of resin, which has been severely degraded in the burial environment; the brownish-red fragmented remains are in an extremely fragile condition and information about the chemical composition was required before urgent conservation was undertaken. Raman spectra excited at 1064 nm showed the presence of triterpenoid materials in the main body of the artefact, and indicated that the red-brown coating was not iron(III) oxide as suspected but rather degraded resin. Comparison with contemporary resins has facilitated the partial identification of the material in this important artefact as a triterpenoid-rich material, which is closely similar to the Pistacia species. A possible archaeological link to the Jatobá do Cerrado ( Hymenaea stigonocarpa Mart.) resin has been excluded as the Raman spectra of this resin specimen and the tembetá do not match; indeed, the Jatobá do Cerrado resin specimen belongs to a diterpenoid-rich classification as befits its Hymenaea species.

de Faria, Dalva L. A.; Edwards, Howell G. M.; Afonso, Marisa C.; Brody, Rachel H.; Morais, José L.

2004-06-01

316

Spectroscopic Studies on Small Molecules: Chlorine Containing Compounds in the Gas Phase and Electrolytes in Formamide.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. The work presented in this thesis is concerned with the spectroscopic studies on the small molecules: chlorine containing compounds in the gaseous phase and electrolytes in formamide. Firstly, the work is concerned with the observation and analysis of the ro-vibrational spectra of some symmetric top molecules in the gas phase. The millimetre wave spectra of CH_3 ^{37}Cl in its gamma _3 state, have been measured and analysed to give the rotational constants and the centrifugal distortion constants together with values of the quadrupole coupling constants. The values agree well with the less precise values from high resolution infrared spectra for the ground state of CH_3^{37 }Cl. The quadrupole effects for each state have been evaluated to third order treatment. The microwave and millimetre wave spectra of methyl chloroform, CH_3C^ {35}Cl_3, have been measured and analysed their quadrupole structures in the ground state, the torsional state v_6 = 1 and the lowest doubly degenerate state v _{12} = 1. In the ground and the excited degenerate states, the bond axis quadrupole coupling constants were yielded. Higher order centrifugal distortion constants were obtained in its ground state. The Coriolis coupling constant and the centrifugal distortion constants have been used to provide information on the harmonic force field. Good values of the rotational constant were obtained in the ground state and the lowest doubly degenerate state, and also obtained in the torsional state. In addition the microwave spectra of CHCl _3 and CFCl_{3'} which have no off axis hydrogen atom at the non -chlorine end, were analysed to give the quadrupole coupling constants and the geometrical structure. Secondly, the work is concerned with solutions of electrolytes in non-aqueous solvents and their properties using NMR and Raman Spectroscopy. The influence of lithium chloride dissolved in formamide on the formamide molecule have been investigated using ^1H, ^{13 }C, ^{15}N and ^7Li nuclear magnetic resonance spectroscopy. The spin-lattice and spin-spin relaxation times of ^7Li(spin = 3/2) have also been measured. The solvation number of ^7 Li was obtained from the variations of the chemical shifts due to concentration. Raman spectra of tetrafluoroborate and thiocyanate formamide solutions have given a good evidence for the anion solvation.

Seo, Pil Ja.

317

Theoretical studies of spectroscopic problems of importance for atmospheric radiation measurements  

NASA Technical Reports Server (NTRS)

Many of the instruments used to deduce the physical parameters of the Earth's atmosphere necessary for climate studies or for pollution monitoring (for instance, temperature versus pressure or number densities of trace molecules) rely on the existence of accurate spectroscopic data and an understanding of the physical processes responsible for the absorption or emission of radiation. During the summer, research was either continued or begun on three distinct problems: (1) an improved theoretical framework for the calculation of the far-wing absorption of allowed spectral lines; (2) a refinement of the calculation of the collision-induced fundamental spectrum of N2; and (3) an investigation of possible line-mixing effects in the fundamental spectrum of CH4. Progress in these three areas is summarized below. During the past few years, we have developed a theoretical framework for the calculation of the absorption of radiation by the far wings of spectral lines. Such absorption due to water vapor plays a crucial role in the greenhouse effect as well as limiting the retrieval of temperature profiles from satellite data. Several improvements in the theory have been made and the results are being prepared for publication. Last year we published results for the theoretical calculation of the absorption of radiation due to the dipoles induced during binary collisions of N2 molecules using independently measured molecular parameters; the results were in reasonable agreement with experimental data. However, recent measurements have revealed new fine structure that has been attributed to line-mixing effects. We do not think that this is correct, rather that the structure results from short-range anisotropic dipoles. We are in the process of including this refinement in our theoretical calculation in order to compare with the new experimental data. Subtle changes in the spectra of CH4 measured by researchers at Langley have also been attributed to line-mixing effects. By analyzing the same spectral lines we have attempted to verify or rule out possible line-mixing mechanisms. Due to the complexity and richness of the spectrum of this highly symmetric molecule, as well as the small magnitude of the effects, a detailed first-principle calculation of the mixing is a difficult problem. Before such a program is undertaken it is important to glean as much information as possible concerning the possible mechanisms by a systematic analysis of the existing data.

Tipping, Richard H.

1994-01-01

318

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

319

Laser spectroscopic study of cold host-guest complexes of crown ethers in the gas phase.  

PubMed

A laser spectroscopic study on the structure and dynamics of cold host-guest inclusion complexes of crown ethers (CEs) with various neutral and ionic species in the gas phase is presented. The complexes with neutral guest species are formed by using supersonic free jets, and those with ionic species are generated with electrospray ionization combined with a cold 22-pole ion trap. For CEs, various sizes of 3n-crown-n ethers (n=4, 5, 6, and 8) and their benzene-substituted species are used. For the guest species, water, methanol, ammonia, acetylene, and phenol are employed as neutral guest species, and for charged guest species, alkali metal cations are chosen. The electronic and vibrational spectra of the complexes are measured by using various laser spectroscopic methods; electronic spectra for the neutral complexes are measured by laser-induced fluorescence. Discrimination of different species such as conformers is performed by ultraviolet-ultraviolet hole-burning spectroscopy. The vibrational spectra of selected species are observed by infrared-ultraviolet double-resonance (IR-UV DR) spectroscopy. For the ionic complexes, ultraviolet photodissociation and IR-UV DR spectroscopy are applied. The complex structures are determined by comparing the observed spectra with those of possible structures obtained by density functional theory calculations. How the host CEs change their conformation or which conformer prefers to form unique inclusion complexes are discussed. These results reveal the key interactions for forming special complexes leading to molecular recognition. PMID:23203940

Inokuchi, Yoshiya; Kusaka, Ryoji; Ebata, Takayuki; Boyarkin, Oleg V; Rizzo, Thomas R

2013-03-18

320

A NEAR-INFRARED SPECTROSCOPIC STUDY OF YOUNG FIELD ULTRACOOL DWARFS  

SciTech Connect

We present a near-infrared (0.9-2.4 {mu}m) spectroscopic study of 73 field ultracool dwarfs having spectroscopic and/or kinematic evidence of youth ( Almost-Equal-To 10-300 Myr). Our sample is composed of 48 low-resolution (R Almost-Equal-To 100) spectra and 41 moderate-resolution spectra (R {approx}> 750-2000). First, we establish a method for spectral typing M5-L7 dwarfs at near-IR wavelengths that is independent of gravity. We find that both visual and index-based classification in the near-IR provides consistent spectral types with optical spectral types, though with a small systematic offset in the case of visual classification at J and K band. Second, we examine features in the spectra of {approx}10 Myr ultracool dwarfs to define a set of gravity-sensitive indices based on FeH, VO, K I, Na I, and H-band continuum shape. We then create an index-based method for classifying the gravities of M6-L5 dwarfs that provides consistent results with gravity classifications from optical spectroscopy. Our index-based classification can distinguish between young and dusty objects. Guided by the resulting classifications, we propose a set of low-gravity spectral standards for the near-IR. Finally, we estimate the ages corresponding to our gravity classifications.

Allers, K. N. [Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837 (United States); Liu, Michael C., E-mail: k.allers@bucknell.edu [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2013-08-01

321

Near infrared spectroscopic reflectance imaging: supervised vs. unsupervised analysis using an art conservation application  

Microsoft Academic Search

Near-IR spectroscopic imaging was used to analyze the remnants of a work of art, a 16th century drawing, attributed to the School of Pieter Bruegel the Elder, which had been significantly altered during a cleaning attempt. Using a combination of a CCD camera and a liquid crystal tunable filter (LCTF), near-IR spectroscopic images (650–1050 nm) were collected from the drawing

James R Mansfield; Michael G Sowa; Claudine Majzels; Cathy Collins; Edward Cloutis; Henry H Mantsch

1999-01-01

322

Quantitative Near Infrared Spectroscopic Analysis of Q-switched Nd:YAG Treatment of Generalized Argyria  

PubMed Central

Background and Objective Generalized argyria is a blue-gray hyperpigmentation of the skin resulting from ingestion or application of silver compounds, such as silver colloid. Case reports have noted improvement after Q-Switched Neodymium--Yttrium Aluminum Garnet laser (1064nm QS Nd:YAG) laser treatment to small surface areas. No reports have objectively monitored laser treatment of generalized argyria over large areas of skin, nor have long-term outcomes been evaluated. Study Design/Materials and Methods An incremental treatment plan was developed for a subject suffering from argyria. A quantitative near infrared spectroscopic measurement technique was employed to non-invasively analyze tissue-pigment characteristics pre- and post-laser treatment. Post-treatment measurements were collected at weeks 1, 2, 3, and 4, and again at 1 year. Results Immediate apparent removal of pigment was observed with 1 Q-switched 1064 nm Nd:YAG laser treatment (3-6 mm spot; 0.8-2 J/cm2) per area. Entire face, neck, upper chest and arms were treated over multiple sessions. Treatments were very painful and general anesthesia was utilized in order to treat large areas. Near-infrared spectroscopy was used to characterize and quantify the concentration of silver particles in the dermis based on the absorption features of the silver particles as well as the optical scattering effects they impart. We were able to estimate that there was, on average, 0.042 mg/mL concentration of silver prior to treatment and that these levels went below the minimum detectable limit of the instrument post-treatment. There was no recurrence of discoloration over the 1-year study period. Conclusion QS 1064 nm laser treatment of argyria is a viable method to restore normal skin pigmentation with no evidence of recurrence over study period. Quantitative spectroscopic measurements, 1) confirmed dyspigmentation was due to silver, 2) validated our clinical assessment of no recurrence up to one year post-treatment and 3) indicated no collateral tissue damage with treatments. PMID:23322674

Saager, Rolf B; Hassan, Khaled M; Kondru, Clement; Durkin, Anthony J; Kelly, Kristen M

2012-01-01

323

Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters  

E-print Network

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. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. 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. To do this, we worked 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 a mode identification corresponding to the detected dominan...

Fumel, Aurelie

2011-01-01

324

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

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

325

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

326

Time-Resolved Photoelectric, Photometric and High-Resolution Spectroscopic Data Analysis of a Luminous Ap Star HD 103498  

Microsoft Academic Search

This paper presents combined results of the photometric and spectroscopic data analysis of a luminous Ap star HD 103498. The time series fast-photometric observations were carried out during 17 nights using the PMT based three-channel fast photometer mounted on the 1.04-m Sampurnanand telescope of the ARIES at Nainital. The fast photometric data sets of five nights obtained in 2007 show

S. Joshi; Y. C. Joshi; O. V. Ezhkova; M. Sachkov; T. Ryabchikova; O. Kochukhov; N. K. Chakradhari; S. K. Tiwari

2011-01-01

327

Photoelectron spectroscopic studies on the electronic structures of transition metal clusters and transition metal oxide clusters  

NASA Astrophysics Data System (ADS)

Photoelectron spectroscopic (PES) studies have been conducted on the bare transition metal clusters: Tin/ (n = 1~65),/ Vn/ (n = 1~70),/ Crn/ (n = 1~70),/ Fen/ (n = 1~33), Con/ (n = 1~51) and Nin/ (n = 1~50). The PES spectra of these clusters are taken at several detachment photon energies ranging from the second harmonic (532 nm) to fourth harmonic (266 nm) of the YAG laser and the 193 nm from an ArF excimer laser. Transition metals are very important catalysis elements; the photoelectron spectroscopic studies on the clusters provide a powerful tool for us to understand the metal- metal bonding and their electronic structures atom by atom. The electronic structure of titanium clusters is found to become bulk-like at relative small cluster sizes. It is observed that the 3d band emerges at the eight-atom cluster beyond which the d-band broadens and evolves toward that of the bulk. The vanadium clusters show three regions of spectral evolution: molecular behavior for n = 3-12; transition from molecular to bulk- like for n = 13-17; gradual convergence to bulk for n > 17, for which a surface-like feature is observed to slowly merge into the bulk feature near n = 60. Even-odd alternations are observed in the photoelectron spectra of small Crn clusters. Density functional calculations reveal a unique dimer growth route for chromium clusters up to Cr11, at which a structural transition occurs from the dimer growth to a bulklike body-centered-cubic structure. The PES spectra of the ferromagnetic metal clusters (Fen,/ Con, and Nin) reveal interesting relationships among the electronic structures and reactivity, geometric and magnetic properties, respectively. Photoelectron spectroscopic studies on the transition metal oxide clusters are also conducted. The study on the novel molecules Mx,/ Oy, (M = Ti, V, Cr, Fe, Cu, and Ni) shows the sequential oxidation behavior of the transition metals. Information about the structures and chemical bonding of these oxide molecules is also obtained.

Wu, Hongbin

328

Spectroscopic analysis of soil metal contamination around a derelict mine site in the Blue Mountains, Australia  

NASA Astrophysics Data System (ADS)

Abandoned mine sites pose the potential threat of the heavy metal pollution spread through streams and via runoff leading to contamination of soil and water in their surrounding areas. Regular monitoring of these areas is critical to minimise impacts on water resources, flora and fauna. Conventional ground based monitoring is expensive and sometimes impractical; spectroscopic methods have been emerged as a reliable alternative for this purpose. In this study, the capabilities of the spectroscopy method were examined for modelling soil contamination from around the abandoned silver-zinc mine located at Yerranderie, NSW Australia. The diagnostic characteristics of the original reflectance data were compared with models derived from first and second derivatives of the reflectance data. The results indicate that the models derived from the first derivative of the reflectance data estimate heavy metals significantly more accurately than model derived from the original reflectance. It was also found in this study that there is no need to use second derivative for modelling heavy metal soil contamination. Finally, the results indicate that estimates were of greater accuracy for arsenic and lead compared to other heavy metals, while the estimation for silver was found to be the most erroneous.

Shamsoddini, A.; Raval, S.; Taplin, R.

2014-09-01

329

Spectroscopic analysis of two peculiar emission line stars: RJHA 49 and SS73 21  

E-print Network

Aims: To investigate the spectra and the evolutionary stages of two peculiar emission-line stars: RJHA 49 and SS73 21. Methods: We used low and high resolution optical data. Line identifications and measurements were performed for several features in their spectra. Results: For each object, we have derived the extinction and the excitation temperature from a set of [Fe II] lines, and the electron density from [N II] lines. For RJHA 49, no detailed spectroscopic study was done so far. Regarding SS73 21, our low resolution spectrum have confirmed the main characteristics found in previous works. On the other side, from our high resolution data, we have found that the Halpha line presents a double-peak, in contrast with the suggestion in the literature that it should reveal a P-Cygni profile. Surprisingly, we found a few He I transitions resembling P-Cygni profiles (e.g. He I 5876), directly suggesting that mass loss is active in SS73 21. We also discussed the nature of these two objects based on the data obtained. Although the evolutionary status of SS73 21 seems well established from previous studies (a proto-planetary nebula), the situation for RJHA 49 is not so clear mainly due to its unknown distance. However, from the strength of [N II] 5754 relative to [O I] 6300, the possibility of RJHA 49 being a LBV object is reduced, and a B[e]-supergiant or a proto-planetary nebula status is more plausible.

C. B. Pereira; W. L. F. Marcolino; M. Machado; F. X. de Araujo

2007-07-19

330

Spectroscopic study of antileishmanial drug incubated in the promastigotes of Leishmania mexicana  

NASA Astrophysics Data System (ADS)

In this work we present spectroscopic study of Boldine (aporphine alkaloid) that possesses important biological activities, in particular, in interaction with the promastigotes of Leishmania mexicana. The results show the applicability of autofluorescence of this drug to determinate the possible mechanism of its biological action. The blue shift and hyperchromic effect in the emission spectrum of the drug in interaction with the parasite cells indicate an energy transference process between them. The morphological change of cell shape of the promastigotes treated with the drug is observed using confocal microscopy. This morphological cell-shape transformation evidences an important interaction between the drug studied and some protein of the parasite cell. Here we describe for the first time the fluorescence properties of the Boldine in the promastigotes of L. mexicana.

Hung, J.; Castillo, J.; Jiménez, G.; Hasegawa, M.; Rodriguez, M.

2003-11-01

331

Photoreceptor pigments for photomovement of microorganisms: some spectroscopic and related studies.  

PubMed

Optical spectroscopy of photoreceptor pigments can substantially contribute to our understanding of the molecular processes which are the basis of photoreception and sensory transduction in photomotile microorganisms. The main spectroscopic techniques are briefly illustrated, together with the most significant types of progress that can be achieved. A few "case examples" are discussed in some detail: Halobacterium, with particular attention to the contribution of flash photolysis studies to the identification and characterization of sensory rhodopsins; Euglena, and the role of in vivo microspectrofluorometry in confirming the flavin nature of its photoreceptor pigment; the first suggestions on the rhodopsin-like nature of the Chlamydomonas photosensing system; Stentor and Blepharisma and the contribution of static and time-resolved fluorescence studies to a molecular model of the primary events in their photoreceptor pigments (stentorin and blepharismin) and systems. PMID:2498475

Lenci, F; Ghetti, F

1989-02-01

332

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

333

Utilization of Solar Dynamics Observatory space weather digital image data for comparative analysis with application to Baryon Oscillation Spectroscopic Survey  

NASA Astrophysics Data System (ADS)

Digital solar image data is available to users with access to standard, mass-market software. Many scientific projects utilize the Flexible Image Transport System (FITS) format, which requires specialized software typically used in astrophysical research. Data in the FITS format includes photometric and spatial calibration information, which may not be useful to researchers working with self-calibrated, comparative approaches. This project examines the advantages of using mass-market software with readily downloadable image data from the Solar Dynamics Observatory for comparative analysis over with the use of specialized software capable of reading data in the FITS format. Comparative analyses of brightness statistics that describe the solar disk in the study of magnetic energy using algorithms included in mass-market software have been shown to give results similar to analyses using FITS data. The entanglement of magnetic energy associated with solar eruptions, as well as the development of such eruptions, has been characterized successfully using mass-market software. The proposed algorithm would help to establish a publicly accessible, computing network that could assist in exploratory studies of all FITS data. The advances in computer, cell phone and tablet technology could incorporate such an approach readily for the enhancement of high school and first-year college space weather education on a global scale. Application to ground based data such as that contained in the Baryon Oscillation Spectroscopic Survey is discussed.

Shekoyan, V.; Dehipawala, S.; Liu, Ernest; Tulsee, Vivek; Armendariz, R.; Tremberger, G.; Holden, T.; Marchese, P.; Cheung, T.

2012-10-01

334

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

335

SPECTROSCOPIC STUDIES OF THE ANAEROBIC ENZYME-SUBSTRATE COMPLEX OF CATECHOL 1,2-DIOXYGENASE  

PubMed Central

The basis of the respective regiospecificities of intradiol and extradiol dioxygenase is poorly understood and may be linked to the protonation state of the bidentate-bound catechol in the enzyme:substrate complex. Previous ultraviolet resonance Raman (UVRR) and UV-visible (UV-vis) difference spectroscopic studies demonstrated that in extradiol dioxygenases, the catechol is bound to the Fe(II) as a monoanion. In this study, we use the same approaches to demonstrate that in catechol 1,2-dioxygenase (C12O), an intradiol enzyme, the catechol binds to the Fe(III) as a dianion. Specifically, features at 290 nm and 1550 cm?1 in the UV-vis and UVRR difference spectra, respectively, are assigned to dianionic catechol based on spectra of the model compound, ferric tris(catecholate). The UVRR spectroscopic band assignments are corroborated by density functional theory (DFT) calculations. In addition, negative features at 240 nm in UV-vis difference spectra and at 1600, 1210, and 1175 cm?1 in UVRR difference spectra match those of a tyrosinate model compound, consistent with protonation of the axial tyrosinate ligand when it is displaced from the ferric ion coordination sphere upon substrate binding. The DFT calculations ascribe the asymmetry of the bound dianionic substrate to the trans donor effect of an equatorially ligated tyrosinate ligand. In addition, the computations suggest that trans donation from the tyrosinate ligand may facilitate charge-transfer from the substrate to yield the iron-bound semiquinone transition state, which is capable of reacting with dioxygen. In illustrating the importance of ligand trans effects in a biological system, the current study demonstrates the power of combining difference UVRR and optical spectroscopies to probe metal ligation in solution. PMID:16316234

Horsman, Geoff P.; Jirasek, Andrew; Vaillancourt, Frederic H.; Barbosa, Christopher J.; Jarzecki, Andrzej A.; Xu, Changliang; Mekmouche, Yasmina; Spiro, Thomas G.; Lipscomb, John D.; Blades, Michael W.; Turner, Robin F.B.; Eltis, Lindsay D.

2008-01-01

336

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.

1989-03-01

337

Infrared spectroscopic ellipsometry study on ferroelectric thin films and narrow gap semiconductors  

NASA Astrophysics Data System (ADS)

A type of high accuracy infrared spectroscopic ellipsometer, by fixed polarizer, rotating polarizer, sample and fixed analyzer PPr(?)SA, has been designed and constructed to study the optical properties of infrared materials in the 2.5 - 12.5 ?m wavelength range. The ellipsometric parameters ? and ? can be derived directly from the detected signal by two ac components with the frequencies of 2? and 4?, avoiding measuring the dc component in addition. The system operations, including data acquisition and reduction, pre-amplifier gain control, incident angle, as well as wavelength setting and scanning, were fully and automatically controlled by a computer. The accuracy in straighthrough is better than 1% on tan? and cos? without any defect correction of instrumental elements, which is quite good for the infrared optical constants measurements. Some typical applications on ferroelectric thin films PZT and BST and narrow gap semiconductors Hg1-xCdxTe are presented.

Chu, Junhao; Huang, Zhiming

2002-12-01

338

Spectroscopic and theoretical study of the o-vanillin hydrazone of the mycobactericidal drug isoniazid  

NASA Astrophysics Data System (ADS)

A complete and detailed study of the hydrazone obtained from condensation of antituberculous isoniazid (hydrazide of the isonicotinic acid, INH) and o-vanillin (2-hydroxy-3-methoxybenzaldehyde, o-HVa) is performed. It includes structural and spectroscopic analyses, comparing experimental and theoretical results. The compound was obtained as a chloride of the pyridinic salt (INHOVA +Cl -) but it will be referred as INHOVA for the sake of simplicity. The conformational space was searched and optimized geometries were determined both in gas phase and including solvent effects. Vibrational (IR and Raman), electronic and NMR spectra were registered and assigned with the help of computational methods based on the Density Functional Theory. Isoniazid hydrazones are good candidates for therapeutic agents against tuberculosis with conserved efficiency and lower toxicity and resistance than parent INH.

González-Baró, Ana C.; Pis-Diez, Reinaldo; Parajón-Costa, Beatriz S.; Rey, Nicolás A.

2012-01-01

339

Spectroscopic and semiempirical studies of new Schiff base of gossypol with allylamine in solution  

NASA Astrophysics Data System (ADS)

The Schiff base of racemic gossypol with allylamine (GSBAL) has been studied by FT-IR, 1H and 13C NMR spectroscopy as well as by the PM5 semiempirical method. The spectroscopic methods have shown that GSBAL Schiff base exists in chloroform solution as enamine-enamine tautomer. The structure of GSBAL and the hydrogen bonds within this structure have been calculated to show that the allyl groups are out-of-planes of naphthalene rings. The strongest intramolecular hydrogen bond within the structure of GSBAL is formed between O 7⋯H-N 16 atoms and it belongs to the medium strong bonds. The other hydrogen bonds, although very weak, play a very important role in stabilising the GSBAL enamine-enamine structure.

Przybylski, Piotr; Ma?uszy?ska, Maria; Brzezinski, Bogumi?

2005-08-01

340

High pressure Raman spectroscopic study of H3Co(CN)6  

NASA Astrophysics Data System (ADS)

H3Co(CN)6 belongs to a class of flexible frame work structured cyanides that exhibit negative thermal expansion along c-axis. In-situ high-pressure Raman spectroscopic studies on H3Co(CN)6 in a diamond-anvil cell were carried out under hydrostatic conditions up to 11 GPa. From the evolution of Raman spectra, splitting of modes and discontinuous changes in the pressure dependence of mode frequencies, a phase transition is identified at 2.3 GPa. In contrast to other modes, a lattice mode at 140 cm-1 and the Co-CN deformation mode 348 cm-1 are found to be softening with increase in pressure. Mode Grüneisen parameter is obtained for the ambient trigonal phase using the pressure dependencies of Raman mode frequencies. From the spectral features, the compound has been found to undergo amorphization around 11 GPa.

Mishra, K. K.; Salke, Nilesh; Achary, S. N.; Tyagi, A. K.; Rao, Rekha

2014-04-01

341

Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process  

NASA Astrophysics Data System (ADS)

Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces.

Kurhekar, Anil Sudhakar; Apte, Prakash R.

2013-02-01

342

Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process  

PubMed Central

Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces. PMID:24619506

Kurhekar, Anil Sudhakar; Apte, Prakash R

2014-01-01

343

Spectroscopic Studies of O-Vacancy Defects in Transition Metal Oxides  

SciTech Connect

Dielectrics comprised of nano-crystalline HfO{sub 2} in gate stacks with thin SiO{sub 2}/SiON interfacial transition regions display significant asymmetries with respect to trapping of Si substrate injected holes and electrons. Based on spectroscopic studies, and guided by ab initio theory, electron and hole traps in HfO{sub 2} and other transition metal elemental oxides are assigned to O-atom divacancies clustered at internal grain boundaries of nano-crystalline films. Engineering solutions in which grain boundary defects are suppressed include: (i) ultra-thin, <2 nm, HfO{sub 2} fims, (ii) chemically phase separated high HfO2 content silicate films, and (iii) non-crystalline Zr/Hf Si oxynitride films.

Lucovsky, G.; Luning, J.; Fleming, L.B.; Ulrich, M.D.; Rowe, J.E.; Seo, H.; Lee, S.; Lysaght, P.; Bersuker, G.

2009-06-03

344

Phosphorus-31 nuclear magnetic resonance spectroscopic study of the canine pancreas: applications to acute alcoholic pancreatitis  

SciTech Connect

The first nuclear magnetic resonance spectroscopic study of the canine pancreas is described. Both in-vivo, ex-vivo protocols and NMR observables are discussed. The stability of the ex-vivo preparation based on the NMR observables is established for at least four hours. The spectra obtained from the in-vivo and ex-vivo preparations exhibited similar metabolite ratios, further validating the model. Metabolite levels were unchanged by a 50% increase in perfusion rate. Only trace amounts of phosphocreatine were observed either in the intact gland or in extracts. Acute alcoholic pancreatitis was mimicked by free fatty acid infusion. Injury resulted in hyperamylasemia, edema (weight gain), increased hematocrit and perfusion pressure, and depressed levels of high energy phosphates.

Janes, N.; Clemens, J.A.; Glickson, J.D.; Cameron, J.L.

1988-01-01

345

Molecular and spectroscopic analysis of non-hydrolyzable sedimentary organic matter from the St. Lawrence Estuary  

NASA Astrophysics Data System (ADS)

Sediments are the ultimate long-term sink for organic carbon (OC) on Earth, thus playing an important role in the global cycles of O2 and CO2. Estuaries and river deltas are major conduits for terrestrial organic matter (OM) into marine systems, where it is mixed with locally produced OM and is eventually deposited and buried in the sediment bed. About 45% of global OC burial occurs along these river deltas and estuaries (Hedges and Keil, 1995), therefore it is of interest to follow OM deposition and preservation in these terrestrial to marine transition zones. We chemically fractionated bulk OM from a series of sediments from the St. Lawrence Estuary and Gulf into distinct reactivity classes. We define three such OM fractions based on pioneering work by Hedges and Keil (1995) who classified OM based on chemical reactivities: labile (degradable at similar rate under oxic and anoxic conditions), non-hydrolyzable (degraded primarily under oxic conditions), and refractory (preserved on long time scales independently of redox conditions). Here we present data on the elemental (C and N), isotopic (?13C and ?15N) and spectroscopic (FTIR, HR-MAS 1H/13C NMR) characterization of the different fractions, focusing primarily on the non-hydrolyzable fraction because of its importance in the long-term burial of OC below the seafloor. We used mild oxidation methods (cupric oxide and ruthenium tetroxide oxidation) followed by chromatographic analysis of the oxidation products. Combining results from the bulk and molecular analytical techniques provides insights into the composition and cycling of non-hydrolyzable OM in transitional system, from which OM preservation can be better understood. Hedges, J. I., Keil, Richard G. (1995). "Sedimentary organic matter preservation: an assessment and speculative synthesis." Marine Chemistry 49(2-3): 81-115.

Ibrahim, M.; Simpson, A. J.; Gelinas, Y.

2011-12-01

346

Model-based spectroscopic analysis of the oral cavity: impact of anatomy  

PubMed Central

In order to evaluate the impact of anatomy on the spectral properties of oral tissue, we used reflectance and fluorescence spectroscopy to characterize nine different anatomic sites. All spectra were collected in vivo from healthy oral mucosa. We analyzed 710 spectra collected from the oral cavity of 79 healthy volunteers. From the spectra, we extracted spectral parameters related to the morphological and biochemical properties of the tissue. The parameter distributions for the nine sites were compared, and we also related the parameters to the physical properties of the tissue site. k-Means cluster analysis was performed to identify sites or groups of sites that showed similar or distinct spectral properties. For the majority of the spectral parameters, certain sites or groups of sites exhibited distinct parameter distributions. Sites that are normally keratinized, most notably the hard palate and gingiva, were distinct from nonkeratinized sites for a number of parameters and frequently clustered together. The considerable degree of spectral contrast (differences in the spectral properties) between anatomic sites was also demonstrated by successfully discriminating between several pairs of sites using only two spectral parameters. We tested whether the 95% confidence interval for the distribution for each parameter, extracted from a subset of the tissue data could correctly characterize a second set of validation data. Excellent classification accuracy was demonstrated. Our results reveal that intrinsic differences in the anatomy of the oral cavity produce significant spectral contrasts between various sites, as reflected in the extracted spectral parameters. This work provides an important foundation for guiding the development of spectroscopic-based diagnostic algorithms for oral cancer. PMID:19123680

McGee, Sasha; Mirkovic, Jelena; Mardirossian, Vartan; Elackattu, Alphi; Yu, Chung-Chieh; Kabani, Sadru; Gallagher, George; Pistey, Robert; Galindo, Luis; Badizadegan, Kamran; Wang, Zimmern; Dasari, Ramachandra; Feld, Michael S.; Grillone, Gregory

2008-01-01

347

ESCA studies of lunar surface chemistry. [Electron Spectroscopic Chemical Analysis  

NASA Technical Reports Server (NTRS)

We have used ESCA to compare the composition of the natural exterior surface in lunar fines samples with that of the interior surface exposed by crushing. Even though the exterior surfaces have been exposed to air a significant amount of Fe in them is reduced. In addition, Ca, Al, and Mg are strongly depleted in exterior surfaces relative to Si, Ti, and Fe. Preferential sputtering by the solar wind is a possible explanation for these changes.

Housley, R. M.; Grant, R. W.

1975-01-01

348

Spectroscopic data and Stark broadening of Cu I and Ag I spectral lines: Selection and analysis  

NASA Astrophysics Data System (ADS)

Optical emission and linear laser absorption spectroscopy techniques were used in investigation of plasma with copper and silver admixture. The method of selection of spectral lines and spectroscopic data with the aim of diagnostics of multicomponent air plasma with two metal vapors admixture was developed. Energy level populations behavior on the Boltzmann plot were used for Cu I and Ag I spectroscopic data selection. In this way the selection of spectroscopic data for some of Cu I and Ag I lines was realized. Stark broadening parameters of Cu I and Ag I were examined. Experimentally obtained temperature and electron density radial distributions were used in the calculation of plasma composition in the assumption of local thermodynamic equilibrium. Linear laser absorption spectroscopy was used to examine the state of plasma.

Babich, I. L.; Boretskij, V. F.; Veklich, A. N.; Semenyshyn, R. V.

2014-10-01

349

SPECTROSCOPIC ANALYSIS OF INTERACTION BETWEEN AN EXTREME-ULTRAVIOLET IMAGING TELESCOPE WAVE AND A CORONAL UPFLOW REGION  

SciTech Connect

We report a spectroscopic analysis of an EUV Imaging Telescope (EIT) wave event that occurred in active region 11081 on 2010 June 12 and was associated with an M2.0 class flare. The wave propagated nearly circularly. The southeastern part of the wave front passed over an upflow region near a magnetic bipole. Using EUV Imaging Spectrometer raster observations for this region, we studied the properties of plasma dynamics in the wave front, as well as the interaction between the wave and the upflow region. We found a weak blueshift for the Fe XII {lambda}195.12 and Fe XIII {lambda}202.04 lines in the wave front. The local velocity along the solar surface, which is deduced from the line-of-sight velocity in the wave front and the projection effect, is much lower than the typical propagation speed of the wave. A more interesting finding is that the upflow and non-thermal velocities in the upflow region are suddenly diminished after the transit of the wave front. This implies a significant change of magnetic field orientation when the wave passed. As the lines in the upflow region are redirected, the velocity along the line of sight is diminished as a result. We suggest that this scenario is more in accordance with what was proposed in the field-line stretching model of EIT waves.

Chen, F.; Ding, M. D.; Chen, P. F. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Harra, L. K., E-mail: dmd@nju.edu.cn [UCL-Mullard Space Science Laboratory, Holmbury St. Mary, Dorking RH5 6NT (United Kingdom)

2011-10-20

350

Comparative two- and three-dimensional analysis of nanoparticle localization in different cell types by Raman spectroscopic imaging  

NASA Astrophysics Data System (ADS)

The increasing production and application of engineered nanomaterials requires a detailed understanding of the potential toxicity of nanoparticles and their uptake in living cells and tissue. For that purpose, a highly sensitive and selective method for detecting single nonlabeled nanoparticles and nanoparticle agglomerations in cells and animal tissue is required. Here, we show that Raman microspectroscopy allows for the specific detection of TiO2 nanoparticles inside cultured NIH/3T3 fibroblasts and RAW 264.7 macrophages. The spatial position of TiO2 nanoparticles and in parallel the relative intracellular concentration and distribution of cellular constituents such as proteins or DNA residues were identified and displayed by construction of two- and three-dimensional Raman maps. The resulting Raman images reflected the significant differences in nanoparticle uptake and intracellular storage of fibroblasts and macrophages. Furthermore, TiO2 nanomaterials could be characterized and the presence of rutile- and anatase-phase TiO2 were determined inside cells. Together, the data shown here prove that Raman spectroscopic imaging is a promising technique for studying the interaction of nanomaterials with living cells and for differentiating intracellular nanoparticles from those localized on the cell membrane. The technology provides a label-free, non-destructive, material-specific analysis of whole cells with high spatial resolution, along with additional information on the current status of the material properties.

Bräutigam, Katharina; Bocklitz, Thomas; Silge, Anja; Dierker, Christian; Ossig, Rainer; Schnekenburger, Jürgen; Cialla, Dana; Rösch, Petra; Popp, Jürgen

2014-09-01

351

Structural Assignment of 6-Oxy Purine Derivatives through Computational Modeling, Synthesis, X-ray Diffraction, and Spectroscopic Analysis  

PubMed Central

6-Oxy purine derivatives have been considered as potential therapeutic agents in various drug discovery efforts reported in literature. However, the structural assignment of this important class of compounds has been controversy concerning the specific position of a hydrogen atom in the structure. To theoretically determine the most favorable type of tautomeric form of 6-oxy purine derivatives, we have carried out first-principles electronic structure calculations on the possible tautomeric forms (A, B, and C) and their relative stability of four representative 6-oxy purine derivatives (compounds 1 to 4). The computational results in both the gas phase and aqueous solution clearly reveal that the most favorable type of tautomeric form of these compounds is A in which a hydrogen atom bonds with N1 atom on the purine ring. To examine the computational results, one of the 6-oxy purine derivatives (i.e. compound 4) has been synthesized and its structure has been characterized by X-ray diffraction and spectroscopic analysis. All of the obtained computational and experimental data are consistent with the conclusion that the 6-oxy purine derivative exists in tautomer A. The conclusive structural assignment reported here is expected to be valuable for future computational studies on 6-oxy purine derivative binding with proteins and for computational drug design involving this type of compounds. PMID:20433186

Zhao, Xinyun; Chen, Xi; Yang, Guang-Fu; Zhan, Chang-Guo

2010-01-01

352

The effect of synthesis temperature on the formation of hydrotalcites in Bayer liquor: a vibrational spectroscopic analysis.  

PubMed

The seawater neutralization process is currently used in the alumina industry to reduce the pH and dissolved metal concentrations in bauxite refinery residues through the precipitation of Mg, Al, and Ca hydroxide and carbonate minerals. This neutralization method is very similar to the co-precipitation method used to synthesize hydrotalcite (Mg6Al2(OH)16CO3.4H2O). This study looks at the effect of temperature on the type of precipitates that form from the seawater neutralization process of Bayer liquor. The Bayer precipitates have been characterized by a variety of techniques, including X-ray diffraction (XRD), Raman spectroscopy, and infrared spectroscopy. The mineralogical composition of Bayer precipitates largely includes hydrotalcite, hydromagnesite, and calcium carbonate species. Analysis with XRD determined that Bayer hydrotalcites that are synthesized at 55 degrees C have a larger interlayer distance, indicating that more anions are removed from Bayer liquor. Vibrational spectroscopic techniques have identified an increase in hydrogen bond strength for precipitates formed at 55 degrees C, suggesting the formation of a more stable Bayer hydrotalcite. Raman spectroscopy identified the intercalation of sulfate and carbonate anions into Bayer hydrotalcites using these synthesis conditions. PMID:19589211

Palmer, Sara J; Frost, Ray L

2009-07-01

353

Static and Time-Resolved Spectroscopic Studies of Low-Symmetry Ru(II) Polypyridyl Aimee E. Curtright and James K. McCusker*  

E-print Network

Static and Time-Resolved Spectroscopic Studies of Low-Symmetry Ru(II) Polypyridyl Complexes Aimee E,2-bipyridine, have been prepared and studied using static and time-resolved electronic and vibrational spectroscopies as a prelude to femtosecond spectroscopic studies of excited-state dynamics. Static electronic

McCusker, James K.

354

Studies of multiple stellar systems - IV. The triple-lined spectroscopic system Gliese 644  

NASA Astrophysics Data System (ADS)

We present a radial velocity study of the triple-lined system Gliese 644 and derive spectroscopic elements for the inner and outer orbits with periods of 2.9655 and 627d. We also utilize old visual data, as well as modern speckle and adaptive optics observations, to derive a new astrometric solution for the outer orbit. These two orbits together allow us to derive masses for each of the three components in the system: MA=0.410+/-0.028 (6.9 per cent), MBa=0.336+/-0.016 (4.7 per cent), and MBb=0.304+/-0.014 (4.7 per cent)Msolar. We suggest that the relative inclination of the two orbits is very small. Our individual masses and spectroscopic light ratios for the three M stars in the Gliese 644 system provide three points for the mass-luminosity relation near the bottom of the main sequence, where the relation is poorly determined. These three points agree well with theoretical models for solar metallicity and an age of 5Gyr. Our radial velocities for Gliese 643 and vB 8, two common proper motion companions of Gliese 644, support the interpretation that all five M stars are moving together in a physically bound group. We discuss possible scenarios for the formation and evolution of this configuration, such as the formation of all five stars in a sequence of fragmentation events leading directly to the hierarchical configuration now observed, versus formation in a small N cluster with subsequent dynamical evolution into the present hierarchical configuration.

Mazeh, Tsevi; Latham, David W.; Goldberg, Elad; Torres, Guillermo; Stefanik, Robert P.; Henry, Todd J.; Zucker, Shay; Gnat, Orly; Ofek, Eran O.

2001-07-01

355

Crystallographic, Kinetic, and Spectroscopic Study of the First Ligninolytic Peroxidase Presenting a Catalytic Tyrosine*  

PubMed Central

Trametes cervina lignin peroxidase (LiP) is a unique enzyme lacking the catalytic tryptophan strictly conserved in all other LiPs and versatile peroxidases (more than 30 sequences available). Recombinant T. cervina LiP and site-directed variants were investigated by crystallographic, kinetic, and spectroscopic techniques. The crystal structure shows three substrate oxidation site candidates involving His-170, Asp-146, and Tyr-181. Steady-state kinetics for oxidation of veratryl alcohol (the typical LiP substrate) by variants at the above three residues reveals a crucial role of Tyr-181 in LiP activity. Moreover, assays with ferrocytochrome c show that its ability to oxidize large molecules (a requisite property for oxidation of the lignin polymer) originates in Tyr-181. This residue is also involved in the oxidation of 1,4-dimethoxybenzene, a reaction initiated by the one-electron abstraction with formation of substrate cation radical, as described for the well known Phanerochaete chrysosporium LiP. Detailed spectroscopic and kinetic investigations, including low temperature EPR, show that the porphyrin radical in the two-electron activated T. cervina LiP is unstable and rapidly receives one electron from Tyr-181, forming a catalytic protein radical, which is identified as an H-bonded neutral tyrosyl radical. The crystal structure reveals a partially exposed location of Tyr-181, compatible with its catalytic role, and several neighbor residues probably contributing to catalysis: (i) by enabling substrate recognition by aromatic interactions; (ii) by acting as proton acceptor/donor from Tyr-181 or H-bonding the radical form; and (iii) by providing the acidic environment that would facilitate oxidation. This is the first structure-function study of the only ligninolytic peroxidase described to date that has a catalytic tyrosine. PMID:21367853

Miki, Yuta; Calvino, Fabiola R.; Pogni, Rebecca; Giansanti, Stefania; Ruiz-Duenas, Francisco J.; Martinez, Maria Jesus; Basosi, Riccardo; Romero, Antonio; Martinez, Angel T.

2011-01-01

356

Raman spectroscopic study of a post-medieval wall painting in need of conservation.  

PubMed

Raman spectroscopic studies of four specimens from an important angel wall painting in need of conservation work in a medieval church have provided some information about the pigments and pigment compositions which will influence possible future preservation and restoration strategies. Excitation of the Raman spectra at 1,064 nm in macroscopic mode and at 785 nm in microscopic mode revealed that the white pigment on the angel's wings was a mixture of barytes with calcite and lead white in minor composition. Although the specimens provided were not directly associated with coloured regions of the painting, yellow and blue microcrystals were found and they were identified as chrome yellow and lazurite, respectively. Red and brown particles were identified as cinnabar/vermilion and haematite. Several green particles were also found but could not be identified. The green and blue crystals could be related to neighbouring coloured regions of the artwork and the yellow colour could be identified as a background to the angel figure. Particles of carbon were found to be dispersed throughout the specimens and can be ascribed to soot from candles, heating stoves or oil lamps providing lighting in the church. No evidence for biological deterioration was found from the spectra. The unusual pigment palette is strongly suggestive of a later date of painting than was originally believed but there is a possibility that an earlier rendition exists underneath. Following a review of the spectroscopic data, a more extensive sampling protocol is recommended, from which some stratigraphic evidence could identify the underlying plaster and possible artwork. PMID:16132151

Edwards, Howell G M; Farwell, Dennis W; Brooke, Christopher J

2005-09-01

357

Spectroscopic and radiative properties study of Nd 3+ doped cadmium-phosphate glasses  

NASA Astrophysics Data System (ADS)

A spectroscopic investigation is performed on Nd 3+ doped cadmium-phosphate glasses. The Judd-Ofelt analysis is applied to the glass system in order to evaluate their potential as both glass laser and amplifier materials. The phenomenological Judd-Ofelt parameters ?(2), ?(4), and ?(6) are determined, their values are 4.80×10 -20, 6.18×10 -20, and 7.14×10 -20 cm -2, respectively. The quality factor for glass system is 0.86. Predicted radiative decay rates and branching ratios of transitions from Nd 3+4F 3/2 state to the 4I J manifolds are determined and analyzed. The calculated lifetime of the 4F 3/2 metastable state of Nd 3+ is 31 ?s. The results showed that 4F 3/2 to 4I 11/2 transition, with fluorescence at 1056 nm, has the most potential for laser application. Photoluminescence up-conversion under excitation at 488 nm laser light exhibits three emission bands of Nd 3+ ions at 541 (green), 601 (orange), and 677 nm (red). These emission bands are assigned to 4G 7/2? 4I 9/2, 4G 7/2? 4I 11/2, and 4G 7/2? 4I 13/2 transitions, respectively. Analysis of luminescence spectra enhances the use of glass system in optical displays, lasers, and optical memory devices.

Mahmoud, K. H.

2010-12-01

358

Ab initio/DFT electronic structure calculations, spectroscopic studies of 5-bromo-2-pyridinecarbonitrile - A comparative study  

NASA Astrophysics Data System (ADS)

Fourier transform infrared (FTIR) and FT-Raman spectra have been recorded and extensive spectroscopic investigations have been carried out on 5-bromo-2-pyridinecarbonitrile (5B2PC). The optimized geometries, wavenumber and intensity of the vibrational bands of (5B2PC) have been calculated using density functional level of theory (DFT/B3LYP) employing 6-311G(d,p) basis set. On the basis of the comparison between calculated and experimental results, assignments of the fundamental vibrational modes are examined. The molecular stability and bond strength were investigated by applying the natural bond orbital (NBO) analysis. The electronic properties like HOMO-LUMO analysis of (5B2PC) have been reported.

Kandasamy, M.; Velraj, G.

2012-08-01

359

Raman Spectroscopic Analysis of Geological and Biogeological Specimens of Relevance to the ExoMars Mission  

PubMed Central

Abstract A novel miniaturized Raman spectrometer is scheduled to fly as part of the analytical instrumentation package on an ESA remote robotic lander in the ESA/Roscosmos ExoMars mission to search for evidence for extant or extinct life on Mars in 2018. The Raman spectrometer will be part of the first-pass analytical stage of the sampling procedure, following detailed surface examination by the PanCam scanning camera unit on the ExoMars rover vehicle. The requirements of the analytical protocol are stringent and critical; this study represents a laboratory blind interrogation of specimens that form a list of materials that are of relevance to martian exploration and at this stage simulates a test of current laboratory instrumentation to highlight the Raman technique strengths and possible weaknesses that may be encountered in practice on the martian surface and from which future studies could be formulated. In this preliminary exercise, some 10 samples that are considered terrestrial representatives of the mineralogy and possible biogeologically modified structures that may be identified on Mars have been examined with Raman spectroscopy, and conclusions have been drawn about the viability of the unambiguous spectral identification of biomolecular life signatures. It is concluded that the Raman spectroscopic technique does indeed demonstrate the capability to identify biomolecular signatures and the mineralogy in real-world terrestrial samples with a very high degree of success without any preconception being made about their origin and classification. Key Words: Biosignatures—Mars Exploration Rovers—Raman spectroscopy—Search for life (biosignatures)—Planetary instrumentation. Astrobiology 13, 543–549. PMID:23758166

Edwards, Howell G.M.; Ingley, Richard; Parnell, John; Vitek, Petr; Jehlicka, Jan

2013-01-01

360

Using light to study boundary lubrication: spectroscopic study of confined fluids.  

PubMed

Several instrumental developments to examine the spectroscopic response of molecularly thin fluids confined between mica sheets are described. They are predicated on using a redesigned surface forces apparatus where dielectric coatings, transparent to light at needed optical wavelengths, retain the ability to measure interferometric thickness at other optical wavelengths. Examples of recent measurements are presented using confocal laser Raman spectroscopy to evaluate how molecules orient as well as to perform chemical imaging. Other examples are presented using confocal fluorescence recovery after photobleaching to evaluate translational diffusion of confined polymer melts. The advantage of separating the mechanical average (force and friction) from direct information about structure and mobility at the molecular level is stressed. PMID:18156129

Bae, Sung Chul; Wong, Janet S; Kim, Minsu; Jiang, Shan; Hong, Liang; Granick, Steve

2008-04-28

361

Solvation of Magnesium Dication: Molecular Dynamics Simulation and Vibrational Spectroscopic Study of Magnesium Chloride in Aqueous Solutions  

E-print Network

Solvation of Magnesium Dication: Molecular Dynamics Simulation and Vibrational Spectroscopic Study of Magnesium Chloride in Aqueous Solutions Karen M. Callahan, Nadia N. Casillas-Ituarte, Martina Roeselova 26, 2010 Magnesium dication plays many significant roles in biochemistry. While it is available

362

Polarization-Modulated Infrared Reflection Absorption Spectroscopic Studies of a Hydrogen-Bonding Network at the Air-Water Interface  

E-print Network

Polarization-Modulated Infrared Reflection Absorption Spectroscopic Studies of a Hydrogen-Bonding, 33405 Talence, France ReceiVed: NoVember 11, 1998; In Final Form: February 2, 1999 The hydrogen-bonding absorption spectroscopy (PM-IRRAS). The molecular structure and orientation of the 1:1 hydrogen- bonding

Rusell, K.C.

363

Spectroscopic studies on the binding interaction of phenothiazinium dyes toluidine blue O, azure A and azure B to DNA  

NASA Astrophysics Data System (ADS)

In this study a detailed characterization of the binding aspects of three phenothiazinium dyes, toluidine blue O (TBO), azure A and azure B with herring testes DNA is presented employing spectroscopic techniques. The absorbance and fluorescence properties of these dyes have been remarkably modified upon binding with DNA and the interaction is manifested through noncooperative binding as revealed form non-linear Scatchard plots with negative slopes at all binding ratios. The binding clearly revealed the high preference of TBO to DNA followed by the other two dyes azure A and azure B. The affinity of TBO was higher by about two times than that of the azures. From the series of studies using absorption, steady-state emission, the effect of ferrocyanide ion-induced steady-state fluorescence quenching, fluorescence polarization anisotropy, circular dichroism, the mode of binding of these dyes to the DNA double helix has been substantiated to be principally intercalative in nature. The stoichiometry of the association of these dyes to DNA was determined by the continuous variation analysis of Job from fluorescence data. The conformational aspects of the interaction was delineated from circular dichroism studies wherein higher perturbation was observed with TBO. Hydrodynamic study using viscosity measurements of linear rod like DNA confirmed that the binding was intercalative and strongest for TBO and weaker for azure A and azure B. The utility of the present work lies in exploring the potential binding applicability of these dyes to DNA for their development as effective therapeutic agents.

Paul, Puja; Suresh Kumar, Gopinatha

2013-04-01

364

Spectroscopic studies on the binding interaction of phenothiazinium dyes toluidine blue O, azure A and azure B to DNA.  

PubMed

In this study a detailed characterization of the binding aspects of three phenothiazinium dyes, toluidine blue O (TBO), azure A and azure B with herring testes DNA is presented employing spectroscopic techniques. The absorbance and fluorescence properties of these dyes have been remarkably modified upon binding with DNA and the interaction is manifested through noncooperative binding as revealed form non-linear Scatchard plots with negative slopes at all binding ratios. The binding clearly revealed the high preference of TBO to DNA followed by the other two dyes azure A and azure B. The affinity of TBO was higher by about two times than that of the azures. From the series of studies using absorption, steady-state emission, the effect of ferrocyanide ion-induced steady-state fluorescence quenching, fluorescence polarization anisotropy, circular dichroism, the mode of binding of these dyes to the DNA double helix has been substantiated to be principally intercalative in nature. The stoichiometry of the association of these dyes to DNA was determined by the continuous variation analysis of Job from fluorescence data. The conformational aspects of the interaction was delineated from circular dichroism studies wherein higher perturbation was observed with TBO. Hydrodynamic study using viscosity measurements of linear rod like DNA confirmed that the binding was intercalative and strongest for TBO and weaker for azure A and azure B. The utility of the present work lies in exploring the potential binding applicability of these dyes to DNA for their development as effective therapeutic agents. PMID:23434558

Paul, Puja; Suresh Kumar, Gopinatha

2013-04-15

365

Spectroscopic Properties of Cool Stars in the SDSS: An Analysis of Magnetic Activity and a Search for Subdwarfs  

E-print Network

We present a spectroscopic analysis of nearly 8000 late-type dwarfs in the Sloan Digital Sky Survey. Using the Halpha emission line as an activity indicator, we investigate the fraction of active stars as a function of spectral type and find a peak near type M8, confirming previous results. In contrast to past findings, we find that not all M7-M8 stars are active. We show that this may be a selection effect of the distance distributions of previous samples, as the active stars appear to be concentrated near the Galactic Plane. We also examine the activity strength (ratio of the luminosity emitted in Halpha to the bolometric luminosity) for each star, and find that the mean activity strength is constant over the range M0-M5 and declines at later types. The decline begins at a slightly earlier spectral type than previously found. We explore the effect that activity has on the broadband photometric colors and find no significant differences between active and inactive stars. We also carry out a search for subdwarfs using spectroscopic metallicity indicators, and find 60 subdwarf candidates. Several of these candidates are near the extreme subdwarf boundary. The spectroscopic subdwarf candidates are redder by \\~0.2 magnitudes in g-r compared to disk dwarfs at the same r-i color.

Andrew A. West; Suzanne L. Hawley; Lucianne M. Walkowicz; Kevin R. Covey; Nicole M. Silvestri; Sean N. Raymond; Hugh C. Harris; Jeffrey A. Munn; Peregrine M. McGehee; Zeljko Ivezic; J. Brinkmann

2004-03-19

366

Spectroscopic analysis of Ho3+ transitions in different modifier oxide based lithium-fluoro-borate glasses  

NASA Astrophysics Data System (ADS)

In recent investigations it was observed that the presence of different structural groups in borate glasses was favorable for spectroscopic investigations of rare earth doped borate glasses. Consequent to these observations, the heavy metal fluoride glasses doped with Ho3+ ions received much attention due to their wide transparency in the ultraviolet to infrared region. Keeping these observations in view, the present paper makes an attempt to present spectral investigations of Ho3+ doped lithium-fluoro-borate glasses of the compositions Li2B4O7-BaF2-NaF-MO (where M=Mg, Ca, Cd and Pb), Li2B4O7-BaF2-NaF-MgO-CaO and Li2B4O7-BaF2-NaF-CdO-PbO. These rare earth doped glasses were synthesized by melt quenching technique and an investigation was carried out to observe the structural (SEM and FT-IR) and optical (absorption and luminescence) properties. The paper also aims at the determination of three phenomenological Judd-Ofelt intensity parameters and special attention was paid to study the emission properties by employing the J-O intensity parameters. The visible emission spectra of Ho3+ ion in different lithium-fluoro-borate glasses were recorded by exciting the samples at 409 nm. The results revealed that among all the glass matrices, cadmium glass matrix have shown higher stimulated emission cross-section, which indicates that this is a good lasing material at this wavelength and highly useful for laser excitation.

Balakrishna, A.; Rajesh, D.; Ratnakaram, Y. C.

2014-10-01

367

Binding of Phenazinium Dye Safranin T to Polyriboadenylic Acid: Spectroscopic and Thermodynamic Study  

PubMed Central

Here, we report results from experiments designed to explore the association of the phenazinium dye safranin T (ST, 3,7-diamino-2,8-dimethyl-5-phenylphenazinium chloride) with single and double stranded form of polyriboadenylic acid (hereafter poly-A) using several spectroscopic techniques. We demonstrate that the dye binds to single stranded polyriboadenylic acid (hereafter ss poly-A) with high affinity while it does not interact at all with the double stranded (ds) form of the polynucleotide. Fluorescence and absorption spectral studies reveal the molecular aspects of binding of ST to single stranded form of the polynucleotide. This observation is also supported by the circular dichroism study. Thermodynamic data obtained from temperature dependence of binding constant reveals that association is driven by negative enthalpy change and opposed by negative entropy change. Ferrocyanide quenching studies have shown intercalative binding of ST to ss poly-A. Experiments on viscosity measurements confirm the binding mode of the dye to be intercalative. The effect of [Na+] ion concentration on the binding process suggests the role of electrostatic forces in the complexation. Present studies reveal the utility of the dye in probing nucleic acid structure. PMID:24498422

Roy, Snigdha; Das, Suman

2014-01-01

368

Spectroscopic study of the Moses Lake dune field, Washington: Determination of compositional distributions and source lithologies  

NASA Astrophysics Data System (ADS)

Source lithologies and transport histories of materials within the Ephrata Fan are investigated. Data were collected using a variety of remote-sensing, laboratory spectroscopic, and field observations and techniques. Laboratory thermal emission spectra were collected of bedrock within the Grand Coulee, dune samples, and clast deposits. Factor analysis, target transformation, and end-member recovery techniques were applied to the set of dune samples as well as a set of grain size fractions. The dune sample spectra are composed of three components that represent basalt, granodiorite, and clay compositions. The basalt and granodiorite components are similar to spectra of clast and bedrock samples from the Grand Coulee and the Ephrata Fan. The clay component is similar to weathering surfaces located within the dune field. The same components were recovered from the set of grain size fractions from a single dune sample demonstrating a relatively higher basalt concentration with grain sizes greater than ~250 ?m. Thermal Infrared Multispectral Scanner (TIMS) data display significant intradune compositional variation and no discernable interdune compositional variation, indicating that the basalt and granodiorite components were likely deposited simultaneously and subsequently separated by wind based on grain size. Basalt and granodiorite bedrock units within the Channeled Scablands are source materials for the deposits within the Ephrata Fan and Moses Lake dune field. The Columbia River, located 20 km west of the dune field, is not a likely source of material.

Bandfield, Joshua L.; Edgett, Kenneth S.; Christensen, Philip R.

2002-11-01

369

Spectroscopic and structural studies of allyl urethane derivative of Monensin A sodium salt  

NASA Astrophysics Data System (ADS)

A new derivative of polyether antibiotic Monensin A sodium salt its allyl urethane (MON-UR2-Na) was synthesised and its structure was studied by X-ray, FT-IR, NMR, and ESI-MS methods. The results of these studies demonstrated that the oxygen atom of the Cdbnd O urethane group is not engaged in the coordination of the Na+ as postulated previously. The crystal space group is P21 with a = 12.0378(11), b = 12.4495(11), c = 14.9690(14), ? = 94.791(8) and Z = 2. The structure determined in the present study exhibits significant differences with respect to the earlier published structure of phenyl urethane of Monensin. A comparison of these structures clearly shows that not only the functional urethane group but also its substituent strongly influence the structure of this type of derivatives of Monensin A. X-ray data and spectroscopic and spectrometric behaviour of the new derivative of Monensin A are discussed in detail and compared to the structure of phenyl urethane of Monensin A sodium salt.

Huczy?ski, Adam; Janczak, Jan; Brzezinski, Bogumil; Bartl, Franz

2013-07-01

370

Spectroscopic diagnostics for liquid lithium divertor studies on National Spherical Torus Experiment  

SciTech Connect

The use of lithium-coated plasma facing components for plasma density control is studied in the National Spherical Torus Experiment (NSTX). A recently installed liquid lithium divertor (LLD) module has a porous molybdenum surface, separated by a stainless steel liner from a heated copper substrate. Lithium is deposited on the LLD from two evaporators. Two new spectroscopic diagnostics are installed to study the plasma surface interactions on the LLD: (1) A 20-element absolute extreme ultraviolet (AXUV) diode array with a 6 nm bandpass filter centered at 121.6 nm (the Lyman-{alpha} transition) for spatially resolved divertor recycling rate measurements in the highly reflective LLD environment, and (2) an ultraviolet-visible-near infrared R=0.67 m imaging Czerny-Turner spectrometer for spatially resolved divertor D I, Li I-II, C I-IV, Mo I, D{sub 2}, LiD, CD emission and ion temperature on and around the LLD module. The use of photometrically calibrated measurements together with atomic physics factors enables studies of recycling and impurity particle fluxes as functions of LLD temperature, ion flux, and divertor geometry.

Soukhanovskii, V. A. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Roquemore, A. L.; Bell, R. E.; Kaita, R.; Kugel, H. W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2010-10-15

371

Raman spectroscopic study of keratin 8 knockdown oral squamous cell carcinoma derived cells  

NASA Astrophysics Data System (ADS)

Keratins are one of most widely used markers for oral cancers. Keratin 8 and 18 are expressed in simple epithelia and perform both mechanical and regulatory functions. Their expression are not seen in normal oral tissues but are often expressed in oral squamous cell carcinoma. Aberrant expression of keratins 8 and 18 is most common change in human oral cancer. Optical-spectroscopic methods are sensitive to biochemical changes and being projected as novel diagnostic tools for cancer diagnosis. Aim of this study was to evaluate potentials of Raman spectroscopy in detecting minor changes associated with differential level of keratin expression in tongue-cancer-derived AW13516 cells. Knockdown clones for K8 were generated and synchronized by growing under serum-free conditions. Cell pellets of three independent experiments in duplicate were used for recording Raman spectra with fiberoptic-probe coupled HE-785 Raman-instrument. A total of 123 and 96 spectra from knockdown clones and vector controls respectively in 1200-1800 cm-1 region were successfully utilized for classification using LDA. Two separate clusters with classification-efficiency of ~95% were obtained. Leave-one-out cross-validation yielded ~63% efficiency. Findings of the study demonstrate the potentials of Raman spectroscopy in detecting even subtle changes such as variations in keratin expression levels. Future studies towards identifying Raman signals from keratin in oral cells can help in precise cancer diagnosis.

Singh, S. P.; Alam, Hunain; Dmello, Crismita; Vaidya, Milind M.; Krishna, C. Murali

2012-03-01

372

Spectroscopic studies on the spontaneous assembly of phenosafranin on glycosaminoglycans templates  

NASA Astrophysics Data System (ADS)

Spectroscopic studies showed that binding of phenosafranin (PSF) molecules to glycosaminoglycans (GAGs) resulted in the following observations: (i) appearance of a 52.6 nm hypsochromic shift of the visible absorption band; (ii) static quenching of fluorescence from PSF; (iii) induction of strong circular dichroism (CD) signal of PSF. Stoichiometry of the PSF-GAGs complex was determined by spectrophotometric titration, spectrofluorimetric titration and MacIntosh extraction method. These studies demonstrated the formation of the extended helical PSF array aligned on the helical backbone of GAGs templates by electrostatic force, and the dimeric binding mode of PSF to each anionic site was proposed. The comparative studies between PSF-heparin (Hep) and PSF-chondroitin 4-sulfate (CS) complexes revealed that: (i) stoichiometry of PSF-Hep complex was 1.8 times of PSF-CS complex; (ii) Hep was more effective than CS (1.8 times) in decreasing the absorbance of PSF; and (iii) Stern-Volmer constants of the Hep-PSF system were greater than that of the CS-PSF system. These differences were attributed to the different charge density on the Hep and CS molecules, which in turn suggested that the electrostatic force was dominant in the interaction between PSF and GAGs.

Zhang, Shuzhen; Zhao, Fenglin; Li, Na; Li, Ke'an; Tong, Shenyang

2002-10-01

373

Synthesis, spectroscopic and thermal studies of some IIB group complexes with a new N2-Schiff base ligand.  

PubMed

Synthesis, spectroscopic and thermal studies of some complexes of a new N(2)-Schiff base ligand of N(1),N(2)-bis((E)-2-methyl-3-phenylallylidene)ethane-1,2-diamine (L) with a general formula of MLX(2) (M = Zn(II), Cd(II) and Hg(II); X = Cl(-), Br(-), I(-), SCN(-) and N(3)(-)) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-vis spectra, FT-IR spectra, MS, (1)H NMR and (13)C NMR spectra. The conductivity measurement as well as spectral data indicated that the complexes are non-electrolyte. (1)H and (13)C NMR spectra have been studied in DMSO-d(6) and/or CDCl(3). The thermal behavior of the complexes shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. Activation thermodynamic parameters of decomposition such as E*, ?H*, ?S* and ?G* were calculated from TG curves. PMID:21733744

Montazerozohori, Morteza; Khani, Sara; Tavakol, Hosein; Hojjati, Ahmad; Kazemi, Mostafa

2011-10-15

374

Spectroscopic study of humic acids fractionated by means of tangential ultrafiltration  

NASA Astrophysics Data System (ADS)

Different chemical and spectroscopic techniques—diffuse reflectance infrared Fourier transform (DRIFT), surface-enhanced Raman spectroscopy (SERS), and 1H, 13C nuclear magnetic resonance (NMR) have been applied to investigate a peat humic acid (HA) separated by tangential ultrafiltration into different nominal molecular weight (NMW) fractions. Each fraction analyzed showed a characteristic DRIFT and NMR pattern. High nominal molecular weight fractions were mainly characterized by long chains of methyl and methylene groups and poorly substituted aromatic rings, while in low nominal molecular weight fractions (L-NMW), phenolic and oxygen-containing groups were predominant. A comparative study on fractions before and after treatment with 0.5 M HCl was carried out. Purified fractions showed either an increase in the carboxylate and phenolic OH groups or an improvement in signal-to-noise ratio of their NMR spectra. The SERS study of NMW fractions allowed significative information on structure and conformation of these fractions. In particular, L-NMW fractions showed a great structural modification, when different alkaline extractants or treatment with HCl were used. Humic-like substances obtained by catechol and gallic acid polymerization on metal surface were investigated using SERS. The SERS spectra of these polymers were compared and discussed with those of NMW HA fractions.

Francioso, O.; Sánchez-Cortés, S.; Casarini, D.; Garcia-Ramos, J. V.; Ciavatta, C.; Gessa, C.

2002-05-01

375

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

376

Molecular spectroscopic studies on the interaction of ferulic acid with calf thymus DNA  

NASA Astrophysics Data System (ADS)

The interaction between ferulic acid and calf thymus deoxyribonucleic acid (ctDNA) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) was investigated by UV-Vis spectroscopy, fluorescence spectroscopy, DNA melting techniques, and viscosity measurements. Results indicated that a complex of ferulic acid with ctDNA was formed with a binding constant of K290K = 7.60 × 104 L mol-1 and K310K = 4.90 × 104 L mol-1. The thermodynamic parameters enthalpy change (?H°), entropy change (?S°) and Gibbs free energy (?G°) were calculated to be -1.69 × 104 J mol-1, 35.36 J K-1 mol-1 and -2.79 × 104 J mol-1 at 310 K, respectively. The acting forces between ferulic acid and DNA mainly included hydrophobic interaction and hydrogen bonds. Acridine orange displacement studies revealed that ferulic acid can substitute for AO probe in the AO-DNA complex which was indicative of intercalation binding. Thermal denaturation study suggested that the interaction of ferulic acid with DNA could result in the increase of the denaturation temperature, which indicated that the stabilization of the DNA helix was increased in the presence of ferulic acid. Spectroscopic techniques together with melting techniques and viscosity determination provided evidences of intercalation mode of binding for the interaction between ferulic acid and ctDNA.

Zhang, Shufang; Sun, Xuejun; Qu, Fengli; Kong, Rongmei

2013-08-01

377

Time-resolved photometric and spectroscopic analysis of the luminous Ap star HD103498  

Microsoft Academic Search

We present the results of the photometric and spectroscopic monitoring of the luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using a three-channel fast photometer attached to the 1.04-m optical telescope at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital. The photometric data from five nights in 2007 show a clear signature of

S. Joshi; T. Ryabchikova; O. Kochukhov; M. Sachkov; S. K. Tiwari; N. K. Chakradhari; N. Piskunov

2010-01-01

378

High-Resolution Calibration of the SDSS\\/SEGUE Spectroscopic Analysis Pipeline  

Microsoft Academic Search

We present a discussion of efforts to obtain external validation of the estimated atmospheric parameters (Teff, log g, [Fe\\/H]) obtained from medium-resolution (R = 2000) SDSS spectroscopy and ugriz photometry, which are being employed for both the completed SDSS-I and the ongoing SEGUE survey. The SDSS\\/SEGUE spectroscopic pipeline makes use of a number of methods for the estimation of each

T. Sivarani; T. C. Beers; Y. Lee; J. Krugler; R. Wilhelm; C. Allende Prieto; C. Sneden; D. L. Lambert; M. Shetrone; J. Johnson; I. Ivans; C. Rockosi; D. Lai; H. Morrison; W. Aoki

2006-01-01

379

AN IMAGING AND SPECTROSCOPIC STUDY OF FOUR STRONG Mg II ABSORBERS REVEALED BY GRB 060418  

SciTech Connect

We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) {approx}> 1 A revealed by the afterglow of GRB 060418 at z{sub GRB} = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z {sub GRB}, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Ly{alpha} systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at {delta} {theta} {approx}< 3.''5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity {approx}0.1 - 1 L{sub *} at impact parameter of {rho} {approx}< 10 h {sup -1} kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of {rho} = 2 - 12 h {sup -1} kpc from the afterglow. At the afterglow's position, we derive a 2{sigma} upper limit to the underlying star-formation rate intensity of 0.0074 M{sub sun} yr{sup -1} kpc{sup -2}.

Pollack, L. K.; Prochaska, J. X. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Chen, H.-W. [Department of Astronomy and Astrophysics and Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Bloom, J. S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)], E-mail: hchen@oddjob.uchicago.edu

2009-08-20

380

Two-Pronged Approach to Overcome Spectroscopically Interfering Organic Compounds with Isotopic Water Analysis  

NASA Astrophysics Data System (ADS)

The ability to measure the stable isotopes of hydrogen (dD) and oxygen (d18O) has become much more accessible with the advent of Cavity Ring-Down Spectroscopy (CRDS) laser optical devices. These small and inexpensive analyzers have led to a significant increase in the acquisition of data from a variety of studies in the fields of groundwater, watershed, and other water source applications. However for some samples, such as those linked to fracking, mining, and other activities where higher than normal concentrations of organic materials are to be found, optical spectroscopy may require an adaptation from current methodologies in order to ensure data confidence. That is because CRDS is able to measure all the components within a spectral region - which will include the spectral characteristics of the isotopologues of water as well as the available features from interfering organic molecules. Although, at the first level, the information from the organic material provides spectral overlaps that can perturb the isotopic ratios, a more thorough review shows that these features are a source of information that will be inherently useful. This presentation will examine the approaches developed within the past year to allow for more accurate analyses of such samples by optical methods. The first approach uses an advanced spectroscopic model to flag the presence of organic material in the sample. Signals from known interfering compounds (i.e., alcohols, ketones, aldehydes, short-chain hydrocarbons, etc.) are incorporated into the overall fit of the measured spectra used to calculate the concentration of the individual isotopes. The second approach uses physical treatment of the sample to break down the organic molecules into non-interfering species. The vaporized liquid or solid sample travels through a cartridge packed with an oxidation catalyst. The interfering organic molecules will undergo high temperature oxidation using O2 present in the air carrier gas stream prior to isotopic measurement with CRDS. This approach is highly effective for organics at lower (< 5% v/v) concentrations and is promising to be extended to some higher concentration contamination as it was recently shown in our preliminary experiments.

Saad, Nabil; Hsiao, Gregor; Chapellet-Volpini, London; Vu, Danthu

2013-04-01

381

Photometric and spectroscopic studies of star-forming regions within Wolf-Rayet galaxies  

E-print Network

We present a study of the properties of star-forming regions within a sample of 7 Wolf-Rayet (WR) galaxies. We analyze their morphologies, colours, star-formation rate (SFR), metallicities, and stellar populations combining broad-band and narrow-band photometry with low-resolution optical spectroscopy. The $UBVRI$ observations were made through the 2m HCT (Himalayan Chandra Telescope) and 1m ARIES telescope. The spectroscopic data were obtained using the Hanle Faint Object Spectrograph Camera (HFOSC) mounted on the 2m HCT. The observed galaxies are NGC 1140, IRAS 07164+5301, NGC 3738, UM 311, NGC 6764, NGC 4861 and NGC 3003. The optical spectra have been used to search for the faint WR features, to confirm that the ionization of the gas is consequence of the massive stars, and to quantify the oxygen abundance of each galaxy using several and independent empirical calibrations. We detected the broad features originated by WR stars in NGC 1140 and NGC 4861 and used them to derive their population of massive sta...

M, Chrisphin Karthick; Sahu, D K; Sanwal, B B; Bisht, Shuchi

2013-01-01

382

Origins of Massive Field Stars in the Galactic Center: a Spectroscopic Study  

E-print Network

Outside of the known star clusters in the Galactic Center, a large number of evolved massive stars have been detected; but their origins remain uncertain. We present a spectroscopic study of eight such stars, based on new Gemini GNIRS and NIFS near-infrared observations. This work has led to the discovery of a new O If+ star. We compare the reddening-corrected J-K vs K diagram for our stars with the massive ones in the Arches cluster and use stellar evolutionary tracks to constrain their ages and masses. The radial velocities of both the stars and their nearby H II regions are also reported. All of the stars are blueshifted relative to the Arches cluster by > 50 km/s. We find that our source P35 has a velocity consistent with that of the surrounding molecular gas. The velocity gradient of nearby ionized gas along the Gemini GNIRS long slit, relative to P35 and the adjacent -30-0 km/s molecular cloud, can best be explained by a pressure-driven flow model. Thus, P35 most likely formed in situ. Three more of our...

Dong, Hui; Morris, Mark R; Wang, Q Daniel; Cotera, Angela

2014-01-01

383

Imaging and spectroscopic performance studies of pixellated CdTe Timepix detector  

NASA Astrophysics Data System (ADS)

In this work the results on imaging and spectroscopic performances of 14 × 14 × 1 mm CdTe detectors with 55 × 55 ?m and 110 × 110 ?m pixel pitch bump-bonded to a Timepix chip are presented. The performance of the 110 × 110 ?m pixel detector was evaluated at the extreme conditions beam line I15 of the Diamond Light Source. The energy of X-rays was set between 25 and 77 keV. The beam was collimated through the edge slits to 20 ?m FWHM incident in the middle of the pixel. The detector was operated in the time-over-threshold mode, allowing direct energy measurement. Energy in the neighbouring pixels was summed for spectra reconstruction. Energy resolution at 77 keV was found to be ?E/E = 3.9%. Comparative imaging and energy resolution studies were carried out between two pixel size detectors with a fluorescence target X-ray tube and radioactive sources. The 110 × 110 ?m pixel detector exhibited systematically better energy resolution in comparison to 55 × 55 ?m. An imaging performance of 55 × 55 ?m pixellated CdTe detector was assessed using the Modulation Transfer Function (MTF) technique and compared to the larger pixel. A considerable degradation in MTF was observed for bias voltages below -300 V. Significant room for improvement of the detector performance was identified both for imaging and spectroscopy and is discussed.

Maneuski, D.; Astromskas, V.; Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Marchal, J.; O'Shea, V.; Stewart, G.; Tartoni, N.; Wilhelm, H.; Wraight, K.; Zain, R. M.

2012-01-01

384

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

PubMed

This work uses ATR-FTIR spectroscopic imaging to study the dissolution of delayed release and pH resistant compressed coating pharmaceutical tablets. Tablets with an inner core and outer shell were constructed using a custom designed compaction cell. The core of the delayed release tablets consisted of hydroxypropyl methylcellulose (HPMC) and caffeine. The shell consisted of microcrystalline cellulose (MCC) and glucose. The core of the pH resistant formulations was an ibuprofen and PEG melt and the shell was constructed from HPMC and a basic buffer. UV/vis spectroscopy was used to monitor the lag-time of drug release and visible optical video imaging was used as a complementary imaging technique with a larger field of view. Two delayed release mechanisms were established. For tablets with soluble shell sections, lag-time was dependent upon rapid shell dissolution. For tablets with less soluble shells, the lag-time was controlled by the rate of dissolution medium ingress through the shell and the subsequent expansion of the wet HPMC core. The pH resistant formulations prevented crystallization of the ibuprofen in the core during dissolution despite an acidic dissolution medium. FTIR imaging produced important information about the physical and chemical processes occurring at the interface between tablet sections during dissolution. PMID:23291036

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

2013-03-12

385

Layered structure of room-temperature ionic liquids in microemulsions by multinuclear NMR spectroscopic studies.  

PubMed

Microemulsions form in mixtures of polar, nonpolar, and amphiphilic molecules. Typical microemulsions employ water as the polar phase. However, microemulsions can form with a polar phase other than water, which hold promise to diversify the range of properties, and hence utility, of microemulsions. Here microemulsions formed by using a room-temperature ionic liquid (RTIL) as the polar phase were created and characterized by using multinuclear NMR spectroscopy. (1)H, (11)B, and (19)F?NMR spectroscopy was applied to explore differences between microemulsions formed by using 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) as the polar phase with a cationic surfactant, benzylhexadecyldimethylammonium chloride (BHDC), and a nonionic surfactant, Triton X-100 (TX-100). NMR spectroscopy showed distinct differences in the behavior of the RTIL as the charge of the surfactant head group varies in the different microemulsion environments. Minor changes in the chemical shifts were observed for [bmim](+) and [BF(4)](-) in the presence of TX-100 suggesting that the surfactant and the ionic liquid are separated in the microemulsion. The large changes in spectroscopic parameters observed are consistent with microstructure formation with layering of [bmim](+) and [BF(4)](-) and migration of Cl(-) within the BHDC microemulsions. Comparisons with NMR results for related ionic compounds in organic and aqueous environments as well as literature studies assisted the development of a simple organizational model for these microstructures. PMID:21547960

Falcone, R Dario; Baruah, Bharat; Gaidamauskas, Ernestas; Rithner, Christopher D; Correa, N Mariano; Silber, Juana J; Crans, Debbie C; Levinger, Nancy E

2011-06-01

386

Licochalcone A bound to bovine serum albumin: a spectroscopic, photophysical and structural study.  

PubMed

The interaction of Licochalcone A (LA) with bovine serum albumin (BSA) was studied by circular dichroism (CD), UV-Vis absorption, fluorescence and laser flash photolysis. The most stable 1 : 1 and 2 : 1 LA : BSA complexes were spectroscopically characterized. Two protein sites of similar affinity are involved in the LA association with both stoichiometries. The fluorescence quantum yield was found to be higher by ca. one order of magnitude for bound LA than for the free molecule. The emission lifetime strongly depended on the protein site. Binding induced an increase in the radiative rate constant for one location and a decrease of the non-radiative rate in the other location. Two LA triplets were evidenced in the protein environment, the first one shorter-lived and the second one longer-lived than in buffer. The BSA fluorescence was quenched in the complexes. FRET was found to be inefficient. Molecular mechanics (MM), molecular dynamics (MD) and quantum mechanical calculations of rotational strength combined with CD data afforded the likely structures of the complexes. One, involving the interaction of LA with Trp212 in domain II, was able to account for most of the observed photophysical effects. MM and MD calculations also showed LA associates in domain III, the lowest energy complex being one with the drug close to Tyr409. PMID:19492108

Monti, Sandra; Manet, Ilse; Manoli, Francesco; Ottani, Stefano; Marconi, Giancarlo

2009-06-01

387

Atomically resolved spectroscopic study of Sr2IrO4: Experiment and theory  

PubMed Central

Particularly in Sr2IrO4, the interplay between spin-orbit coupling, bandwidth and on-site Coulomb repulsion stabilizes a Jeff = 1/2 spin-orbital entangled insulating state at low temperatures. Whether this insulating phase is Mott- or Slater-type, has been under intense debate. We address this issue via spatially resolved imaging and spectroscopic studies of the Sr2IrO4 surface using scanning tunneling microscopy/spectroscopy (STM/S). STS results clearly illustrate the opening of an insulating gap (150 ~ 250?meV) below the Néel temperature (TN), in qualitative agreement with our density-functional theory (DFT) calculations. More importantly, the temperature dependence of the gap is qualitatively consistent with our DFT + dynamical mean field theory (DMFT) results, both showing a continuous transition from a gapped insulating ground state to a non-gap phase as temperatures approach TN. These results indicate a significant Slater character of gap formation, thus suggesting that Sr2IrO4 is a uniquely correlated system, where Slater and Mott-Hubbard-type behaviors coexist. PMID:24166292

Li, Qing; Cao, Guixin; Okamoto, Satoshi; Yi, Jieyu; Lin, Wenzhi; Sales, Brian C.; Yan, Jiaqiang; Arita, Ryotaro; Kunes, Jan; Kozhevnikov, Anton V.; Eguiluz, Adolfo G.; Imada, Masatoshi; Gai, Zheng; Pan, Minghu; Mandrus, David G.

2013-01-01

388

High-pressure behaviour of serpentine minerals: a Raman spectroscopic study  

NASA Astrophysics Data System (ADS)

Four main serpentine varieties can be distinguished on the basis of their microstructures, i.e. lizardite, antigorite, chrysotile and polygonal serpentine. Among these, antigorite is the variety stable under high pressure. In order to understand the structural response of these varieties to pressure, we studied well-characterized serpentine samples by in situ Raman spectroscopy up to 10 GPa, in a diamond-anvil cell. All serpentine varieties can be metastably compressed up to 10 GPa at room temperature without the occurrence of phase transition or amorphization. All spectroscopic pressure-induced changes are fully reversible upon decompression. The vibrational frequencies of antigorite have a slightly larger pressure dependence than those of the other varieties. The O-H-stretching modes of the four varieties have a positive pressure dependence, which indicates that there is no enhancement of hydrogen bonding in serpentine minerals at high pressure. Serpentine minerals display two types of hydroxyl groups in the structure: inner OH groups lie at the centre of each six-fold ring while outer OH groups are considered to link the octahedral sheet of a given 1:1 layer to the tetrahedral sheet of the adjacent 1:1 layer. On the basis of the contrasting behaviour of the Raman bands as a function of pressure, we propose a new assignment of the OH-stretching bands. The strongly pressure-dependent modes are assigned to the vibrations of the outer hydroxyl groups, the less pressure-sensitive peaks to the inner ones.

Auzende, A.-L.; Daniel, I.; Reynard, B.; Lemaire, C.; Guyot, F.

389

Spectroscopic study of milled MnF2 nanoparticles. Size-and-strain-induced photoluminescence enhancement  

NASA Astrophysics Data System (ADS)

This work presents a correlated structural and spectroscopic study on ball-milled MnF2. The aims are to produce impurity-lean particles through particle-size reduction leading to room-temperature photoluminescence (PL) and to modify the electronic states of the emitting centres. Despite non-radiative centres being still present, the PL quenching temperature was increased nearly 80 K, from 120 to 200 K, following this method. Milled MnF2 has particle sizes down to several nanometres, and structural changes from the initial ?-TiO2 structure to the ?-PbO2 phase. Milling favours the presence of adsorbed water on the nanoparticle surface. Time-resolved spectroscopy indicates that the nanoparticle PL consists of a significantly inhomogeneous broadened band with respect to the initial MnF2 PL. The temperature dependence of the lifetime measured at different wavelengths of the emission spectrum indicates the presence of several PL centres, the population of which is controlled by exciton migration and trapping. The widespread occurrence of emitting centres is explained in terms of milling-induced strains, the coexistence of two different structural phases, and the presence of adsorbed water molecules.

Hernández, Ignacio; Rodríguez, Fernando

2007-09-01

390

Spectroscopic study of the high-spin states in 135Pr  

NASA Astrophysics Data System (ADS)

An in-beam spectroscopic study of 135Pr was made using a 91 MeV 120Sn(19F,4n) reaction. Two positive parity bands were observed based on the g7/2 proton orbital with (?,?)=(+,+/-(1/2)). A strongly populated negative parity (-,-(1/2)) band was also seen (based on the h11/2 proton orbital). The unfavored (-,+(1/2)) structure may also be present. In both the positive and negative parity bands the first backbend is attributed to the alignment of two h11/2 protons on the basis of cranked shell model calculations. The crossing frequency was found to increase in the (-,-(1/2)) band because of blocking of the h11/2 orbital. The alignment of protons in 135Pr causes a shift of ? towards ~+10° with nearly collective prolate deformation. Also, there is some evidence for a second backbend and an upbend in the case of positive and negative parity bands, respectively. They could result from the alignment of the h11/2 neutrons.

Semkow, T. M.; Sarantites, D. G.; Honkanen, K.; Abenante, V.; Adler, And L.; Baktash, C.; Johnson, N. R.; Lee, I. Y.; Oshima, M.; Schutz, Y.; Chen, Y. S.; Saladin, J. X.; Chen, C. Y.; Dietzsch, O.; Larabee, A. J.; Riedinger, L. L.; Griffin, H. C.

1986-08-01

391

Conformational heterogeneity of methyl 4-hydroxycinnamate: a gas-phase UV-IR spectroscopic study.  

PubMed

UV excitation and IR absorption spectroscopy on jet-cooled molecules is used to study the conformational heterogeneity of methyl 4-hydroxycinnamate, a model chromophore of the Photoactive Yellow Protein (PYP), and to determine the spectroscopic properties of the various conformers. UV-UV depletion spectroscopy identifies four different species with distinct electronic excitation spectra. Quantum chemical calculations argue that these species are associated with different conformers involving the s-cis/s-trans configuration of the ester with respect to the propenyl C-C single bond and the syn/anti orientation of the phenolic OH group. IR-UV hole-burning spectroscopy is used to record their IR absorption spectra in the fingerprint region. Comparison with IR absorption spectra predicted by quantum chemical calculations provides vibrational markers for each of the conformers, on the basis of which each of the species observed with UV-UV depletion spectroscopy is assigned. Although both DFT and wave function methods reproduce experimental frequencies, we find that calculations at the MP2 level are necessary to obtain agreement with experimentally observed intensities. To elucidate the role of the environment, we compare the IR spectra of the isolated conformers with IR spectra of methyl 4-hydroxycinnamate-water clusters, and with IR spectra of methyl 4-hydroxycinnamate in solution. PMID:23574393

Tan, Eric M M; Amirjalayer, Saeed; Smolarek, Szymon; Vdovin, Alexander; Rijs, Anouk M; Buma, Wybren J

2013-05-01

392

Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate  

NASA Astrophysics Data System (ADS)

In this paper results of optical emission spectroscopic (OES) study of atmospheric pressure microwave 915 MHz argon plasma are presented. The plasma was generated in microwave plasma source (MPS) cavity-resonant type. The aim of research was determination of electron excitation temperature Texc gas temperature Tg and electron number density ne. All experimental tests were performed with a gas flow rate of 100 and 200 l/min and absorbed microwave power PA from 0.25 to 0.9 kW. The emission spectra at the range of 300 - 600 nm were recorded. Boltzmann plot method for argon 5p - 4s and 5d - 4p transition lines allowed to determine Texc at level of 7000 K. Gas temperature was determined by comparing the measured and simulated spectra using LIFBASE program and by analyzing intensities of two groups of unresolved rotational lines of the OH band. Gas temperature ranged 600 - 800 K. The electron number density was determined using the method based on the Stark broadening of hydrogen H? line. The measured ne rang ed 2 × 1015 - 3.5×1015 cm-3, depending on the absorbed microwave power. The described MPS works very stable with various working gases at high flow rates, that makes it an attractive tool for different gas processing.

Miotk, R.; Hrycak, B.; Jasinski, M.; Mizeraczyk, J.

2012-12-01

393

Spectroscopic Study of Extended Star Clusters in Dwarf Galaxy NGC 6822  

E-print Network

We present a spectroscopic study of the four extended star clusters (ESCs) in NGC 6822 based on the data obtained with Gemini Multi-Object Spectrograph (GMOS) on the Gemini-South 8.1m telescope. Their radial velocities derived from the spectra range from $-61.2 \\pm 20.4$ km s$^{-1}$ (for C1) to $-115.34 \\pm 57.9$ km s$^{-1}$ (for C4) and, unlike the intermediate age carbon stars, they do not display any sign of systematic rotation around NGC 6822. The ages and metallicities derived using the Lick indices show that the ESCs are old ($\\geq 8$ Gyr) and metal poor ([Fe/H]$\\lesssim -1.5$). NGC 6822 is found to have both metal poor ([Fe/H]$\\approx -2.0$) and metal rich ([Fe/H]$\\approx -0.9$) star clusters within 15 arcmin (2 kpc) from the center, while only metal poor clusters are observed in the outer halo with $r \\geq 20$ arcmin (2.6 kpc). The kinematics, old ages, and low metallicities of ESCs suggest that ESCs may have accreted into the halo of NGC 6822. Based on the velocity distribution of ESCs, we have deter...

Hwang, Narae; Lee, Myung Gyoon; Lim, Sungsoon; Hodge, Paul W; Kim, Sang Chul; Miller, Bryan; Weisz, Daniel

2014-01-01

394

Raman spectroscopic study of the size-dependent order parameter of barium titanate  

NASA Astrophysics Data System (ADS)

Spherical barium titanate nanoparticles, having a diameter of 50-500 nm, were characterized using micro-Raman spectroscopy at 83 K. Proposed is a calibrated intensity method allowing a spectroscopic estimate of the relative fraction of two solid-state structural phases, where the phases have uniquely identifiable Raman bands. The Raman spectroscopy local probe is broadened to quantify macroscopic characteristics, such as the order parameter. Based on the intensity of the 311 cm-1 mode, it is revealed that the order parameter, ?, of BaTiO3 decreases exponentially with particle size reduction. Similarly, an exponential decrease of the long-range (dipole-dipole) interaction is suggested, based on the Raman shift of the 716 cm-1 mode. An approximate long-range interaction decrease of 3% is estimated when the particle size is reduced from 500 nm to 50 nm. This study provides evidence that BaTiO3 nanoparticles can be modeled as being composed of coexisting cubic and non-cubic phases with relative fraction controlled by the degree of long-range Coulombic interactions.

Sendova, Mariana; Hosterman, Brian D.

2014-06-01

395

Spectroscopic study of the high-spin states in /sup 135/Pr  

SciTech Connect

An in-beam spectroscopic study of /sup 135/Pr was made using a 91 MeV /sup 120/Sn(/sup 19/F,4n) reaction. Two positive parity bands were observed based on the g-italic/sub 7/2/ proton orbital with (..pi..,..cap alpha..) = (+, +- (1/2)). A strongly populated negative parity (-,-(1/2)) band was also seen (based on the h-italic/sub 11/2/ proton orbital). The unfavored (-,+(1/2)) structure may also be present. In both the positive and negative parity bands the first backbend is attributed to the alignment of two h-italic/sub 11/2/ protons on the basis of cranked shell model calculations. The crossing frequency was found to increase in the (-,-(1/2)) band because of blocking of the h-italic/sub 11/2/ orbital. The alignment of protons in /sup 135/Pr causes a shift of ..gamma.. towards --+10/sup 0/ with nearly collective prolate deformation. Also, there is some evidence for a second backbend and an upbend in the case of positive and negative parity bands, respectively. They could result from the alignment of the h-italic/sub 11/2/ neutrons.

Semkow, T.M.; Sarantites, D.G.; Honkanen, K.; Abenante, V.; Adler, a.L.A.; Baktash, C.; Johnson, N.R.; Lee, I.Y.; Oshima, M.; Schutz, Y.; Chen, Y.S.; Saladin, J.X.; Chen, C.Y.; Dietzsch, O.; Larabee, A.J.; Riedinger, L.L.; Griffin, H.C.

1986-08-01

396

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

397

UV\\/vis, 1H, and 13C NMR spectroscopic studies to determine mangiferin p K a values  

Microsoft Academic Search

The acid constants of mangiferin (a natural xanthonoid) in aqueous solution were determined through an UV\\/vis spectroscopic study employing the SQUAD program as a computational tool. A NMR study complements the pKa values assignment and evidences a H-bridge presence on 1-C. The chemical model used was consistent with the experimental data obtained. The pKa values determined with this procedure were

Berenice Gómez-Zaleta; María Teresa Ramírez-Silva; Atilano Gutiérrez; Enrique González-Vergara; Marisol Güizado-Rodríguez; Alberto Rojas-Hernández

2006-01-01

398

Formation of cyanoallene (buta-2, 3-dienenitrile) in the interstellar medium: a quantum chemical and spectroscopic study  

NASA Astrophysics Data System (ADS)

The interstellar medium, filling the vast space between stars, is a rich reservoir of molecular material ranging from simple diatomic molecules to more complex, astrobiologically important molecules such as vinylcyanide, methylcyanodiaccetylene, cyanoallene, etc. Interstellar molecular cyanoallene is one of the most stable isomers of methylcynoacetylene. An attempt has been made to explore the possibility of forming cyanoallene in interstellar space by radical-radical and radical-molecule interaction schemes in the gaseous phase. The formation of cyanoallene starting from some simple, neutral interstellar molecules and radicals has been studied using density functional theory. The reaction energies and structures of the reactants and products show that the formation of cyanoallene is possible in the gaseous phase. Both of the considered reaction paths are totally exothermic and barrierless, thus giving rise to a high probability of occurrence. Rate constants for each step in the formation process of cyanoallene in both the reaction paths are estimated. A full vibrational analysis has been attempted for cyanoallene in the harmonic and anharmonic approximations. Anharmonic spectroscopic parameters such as rotational constants, rotation-vibration coupling constants and centrifugal distortion constants have been calculated.

Singh, Amresh; Shivani; Misra, Alka; Tandon, Poonam

2014-03-01

399

X-ray photoelectron spectroscopic studies of graphitic materials and interfacial interactions in carbon-fiber-reinforced polymer composites  

NASA Astrophysics Data System (ADS)

This dissertation involves the X-ray photoelectron spectroscopic (XPS) study of the chemistry associated with carbon fiber-reinforced composites fabricated using PAN-based carbon fibers and a thermoplastic polyimide resin. The mechanical properties of the ultimate composite are significantly affected by the nature of the fiber/matrix interface. Interfacial interaction can be promoted by the electrochemical modification of the fiber surface. The determination of carbon fiber microstructure was conducted through angle-resolved valence band photoemission studies of highly ordered graphite. The change in orientation of the basal planes and reactive edge sites with take-off angle provided a method for the determination of surface microstructure. The electronic structure of solid-state graphite was described using a band structure model and the results obtained were compared with the multiple scattered wave X a calculations. PAN-based fibers were electrochemically oxidized and studied using monochromatic X-radiation. The extremely narrow natural linewidth of the monochromatized Al K a radiation allowed previously unresolved features to be seen. In addition, sample decomposition due to radiative heat from the X-ray source is eliminated. Fibers that were pretreated by the manufacturer were subjected to further electrochemical oxidation. The fibers behaved in an erratic and non-reproducible manner. The surface treatment was removed by heating the fibers in vacuum, followed by XPS analysis and electrochemical oxidation. The fiber/matrix interface was simulated by coating a very thin layer of the polyimide resin on the surface of the fiber followed by XPS analysis. The validity of a proposed structure for the resin was confirmed by comparison with ab initio calculations conducted on the resin repeat unit. A high level of fiber/matrix interaction was observed for electrochemically oxidized fibers. The possibility of solvent interaction with the fiber surface was eliminated by conducting an experiment involving only the solvent. A possible mechanism for fiber/matrix interaction was suggested.

Viswanathan, Hema L.