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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

UV spectroscopic study and conformational analysis of domperidone  

NASA Astrophysics Data System (ADS)

The UV absorption spectra of domperidone, 2-(3 H)-benzimidazolone and 5-Cl-2-(3 H)-benzimidazolone in CH 3CN have been studied both in the absence and in the presence of hard acids. A theoretical analysis of the electronic transitions of 2-(3 H)-benzimidazolone has also been performed by means of quantum-mechanical methods. Molecular mechanics (force field) calculations have been carried out to characterize the conformational space of domperidone. The results show a large number of conformers lying with 3 kcal mol -1 with respect to the lowest energy structure.

Cignitti, Maurizio; Ramusino, Marina Cotta; Rufini, Leandro

1995-04-01

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

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

5

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.

6

NMR spectroscopic studies of "titanocene"  

E-print Network

NMR SPECTROSCOPIC STUDIES OF "TITANOCENE" A Thea is by DONALD FLOYD BIRKELBACH Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1971 Ma)or Sub...)cot: Chemistry NMR SPECTROSCOPIC STUDIES OF "TITANOCENE" A Thesis by DONALD FLOYD BIRKELBACH Approved as to style and content by: (C ai"iman of Committee) (Head of Department) (Member) (Member) (Member) (Memb er) (Member) May 1971 ABSTRACT NMR...

Birkelbach, Donald Floyd

1971-01-01

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

An experimental and density functional study on conformational and spectroscopic analysis of 5-methoxyindole-2-carboxylic acid  

NASA Astrophysics Data System (ADS)

In this article, a brief conformational and spectroscopic characterization of 5-methoxyindole-2-carboxylic acid (5-MeOICA) via experimental techniques and applications of quantum chemical methods is presented. The conformational analysis of the studied molecule was determined theoretically using density functional computations for ground state, and compared with previously reported experimental findings. The vibrational transitions were examined by measured FT-IR and FT-Raman spectroscopic data, and also results obtained from B3LYP and CAM-B3LYP functionals in combination with 6-311++G(d,p) basis set. The recorded proton and carbon NMR spectra in DMSO solution were analyzed to obtain the exact conformation. Due to intermolecular hydrogen bondings, NMR calculations were performed for the dimeric form of 5-MeOICA and so chemical shifts of those protons were predicted more accurately. Finally, electronic properties of steady compound were identified by a comparative study of UV absorption spectra in ethanol and water solution and TD-DFT calculations.

Cinar, Mehmet; Karabacak, Mehmet; Asiri, Abdullah M.

2015-02-01

9

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

10

A PHOTOMETRIC AND SPECTROSCOPIC STUDY OF DWARF AND GIANT GALAXIES IN THE COMA CLUSTER. I. WIDE-AREA PHOTOMETRIC SURVEY: OBSERVATION AND DATA ANALYSIS1  

E-print Network

A PHOTOMETRIC AND SPECTROSCOPIC STUDY OF DWARF AND GIANT GALAXIES IN THE COMA CLUSTER. I. WIDE 1982), photometric studies (e.g., Strom & Strom 1978; God- win & Peach 1977; Visvanathan & Sandage 1977-AREA PHOTOMETRIC SURVEY: OBSERVATION AND DATA ANALYSIS1 Y. Komiyama,2 M. Sekiguchi,3 N. Kashikawa,4 M. Yagi,4 M

Iye, Masanori

11

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

12

Study on molecular structure, spectroscopic behavior, NBO, and NLO analysis of 3-methylbezothiazole-2-thione.  

PubMed

Experimentally observed spectral data (FT-TR and FT-Raman) of 3-methylbezothiazole-2-thione (3MBT2T) were compared with the spectral data obtained by DFT/B3LYP method using 6-311++G(d,p) basis set. UV-Vis spectrum of the title compound was recorded and the electronic properties, such as frontier molecular orbitals and band gap energies were calculated by TD-DFT approach. The molecular properties like dipole moment, polarizability, first static hyperpolarizability, molecular electrostatic potential surface (MEPs), and contour map were calculated to get a better comprehension of the properties of the title molecule. Natural bond orbital (NBO) analysis was applied to investigate the stability of the molecule arising from charge delocalization. Global and local reactivity descriptors were also computed to predict reactivity and reactive sites on the molecule. PMID:25813170

Chand, Satish; Al-Omary, Fatmah A M; El-Emam, Ali A; Shukla, Vikas K; Prasad, Onkar; Sinha, Leena

2015-07-01

13

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

NASA Astrophysics Data System (ADS)

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

Borho, Nicole; Xu, Yunjie

2007-06-01

14

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

15

FT-IR spectroscopic analysis for studying Clostridium cell response to conversion of enzymatically hydrolyzed hay  

NASA Astrophysics Data System (ADS)

Grass hay is one of assailable cellulose containing non-food agricultural wastes that can be used as a carbohydrate source by microorganisms producing biofuels. In this study three Clostridium strains Clostridium acetobutylicum, Clostridium beijerinckii and Clostridium tetanomorphum, capable of producing acetone, butanol and ethanol (ABE) were adapted to convert enzymatically hydrolyzed hay used as a growth media additive. The results of growth curves, substrate degradation kinetics and FT-IR analyses of bacterial biomass macromolecular composition showed diverse strain-specific cell response to the growth medium composition.

Grube, Mara; Gavare, Marita; Nescerecka, Alina; Tihomirova, Kristina; Mezule, Linda; Juhna, Talis

2013-07-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

17

Studies on the binding of fulvic acid with transferrin by spectroscopic analysis  

NASA Astrophysics Data System (ADS)

Transferrin has shown potential in the delivery of anticancer drugs into primarily proliferating cancer cells that over-express transferrin receptors. Fulvic acid has a wide range of biological and pharmacological activities which caused widespread concerns, the interaction of fulvic acid with human serum transferrin (Tf) has great significance for gaining a deeper insight about anticancer activities of fulvic acid. In this study, the mechanism of interaction between fulvic acid and Tf, has been investigated by using fluorescence quenching, thermodynamics, synchronous fluorescence and circular dichroism (CD) under physiological condition. Our results have shown that fulvic acid binds to Tf and form a new complex, and the calculated apparent association constants are 5.04 × 108 M-1, 5.48 × 107 M-1, 7.38 × 106 M-1 from the fluorescence quenching at 288 K, 298 K, and 310 K. The thermodynamic parameters indicate that hydrogen bonding and weak van der Waals are involved in the interaction between fulvic acid and Tf. The binding of fulvic acid to Tf causes the ?-helix structure content of the protein to reduce, and resulting that peptide chains of Tf become more stretched. Our results have indicated a mechanism of the interaction between fulvic acid and Tf, which may provide information for possible design of methods to deliver drug molecules via transferrin to target tissues and cells effectively.

Zhang, Xiu-feng; Yang, Guang; Dong, Yu; Zhao, Yan-qin; Sun, Xiao-ran; Chen, Lei; Chen, Hong-bo

2015-02-01

18

Multivariate analysis methods for spectroscopic blood analysis  

NASA Astrophysics Data System (ADS)

Blood tests are an essential tool in clinical medicine with the ability diagnosis or monitor various diseases and conditions; however, the complexities of these measurements currently restrict them to a laboratory setting. P&P Optica has developed and currently produces patented high performance spectrometers and is developing a spectrometer-based system for rapid reagent-free blood analysis. An important aspect of this analysis is the need to extract the analyte specific information from the measured signal such that the analyte concentrations can be determined. To this end, advanced chemometric methods are currently being investigated and have been tested using simulated spectra. A blood plasma model was used to generate Raman, near infrared, and optical rotatory dispersion spectra with glucose as the target analyte. The potential of combined chemometric techniques, where multiple spectroscopy modalities are used in a single regression model to improve the prediction ability was investigated using unfold partial least squares and multiblock partial least squares. Results show improvement in the predictions of glucose levels using the combined methods and demonstrate potential for multiblock chemometrics in spectroscopic blood analysis.

Wood, Michael F. G.; Rohani, Arash; Ghazalah, Rashid; Vitkin, I. Alex; Pawluczyk, Romuald

2012-01-01

19

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

20

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

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)

2009-01-01

22

Spectroscopic studies of copper enzymes  

Microsoft Academic Search

Several spectroscopic methods, including absorption, circular dichroism (CD), magnetic CD (MCD), X-ray absorption, resonance Raman, EPR, NMR, and quasi-elastic light-scattering spectroscopy, have been used to probe the structures of copper-containing amine oxidases, nitrite reductase, and nitrous oxide reductase. The basic goals are to determine the copper site structure, electronic properties, and to generate structure-reactivity correlations. Collectively, the results on the

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

1986-01-01

23

Spectroscopic Analysis of Volatile Elements  

NASA Astrophysics Data System (ADS)

We have performed spectral synthesis modeling to measure carbon and oxygen abundances for 297 stars from the Lick and AAT planet search surveys. Of these stars, 27 have known planetary companions and 270 are without detected planets. The abundance of these volatile elements is compared for stars with and without planetary companions, extending the analysis of Fischer & Valenti (2005).

Manrao, E.; Fischer, D.

2005-12-01

24

Analysis of interface layers by spectroscopic ellipsometry  

NASA Astrophysics Data System (ADS)

We investigate the relative validity of the Bruggeman effective-medium approximation and several alloy models to describe interfaces in the analysis of spectroscopic ellipsometric data of laminar samples, using data obtained on an Al xGa 1- xAs multilayer sample fabricated specifically for this purpose. The investigation highlights the types of errors that result from the use of inappropriate models. Optimum results are obtained with the alloy model where the graded-composition regions are approximated with multilayer stacks.

Kim, T. J.; Yoon, J. J.; Kim, Y. D.; Aspnes, D. E.; Klein, M. V.; Ko, D.-S.; Kim, Y.-W.; Elarde, V. C.; Coleman, J. J.

2008-11-01

25

Studying Ink Penetration with Microscopic and Spectroscopic Techniques  

Microsoft Academic Search

Distribution of inkjet ink in paper substrates and the consequences of ink penetration for printing color reproduction have been studied by combining microscopic image processing with spectroscopic analysis. The study focused on the effects of the composition of uncoated paper, for five laboratory papers plus two commercial products, all consisting of similar pulps but with different combinations of additives. In

Li Yang; Andrew Fogden; Nils Pauler; O?rjan Sa?vborg; Bjo?rn Kruse

2006-01-01

26

Spectroscopic analysis of alpha Andromedae  

NASA Astrophysics Data System (ADS)

Coude-spectrographic data for the visible and UV are employed to determine the atmospheric chemical composition of alpha And. Nothing that five previous observations of the star by other researchers failed to produce a consensus for the spectra, the present study considered only lines which were present in all the spectra obtained. The detected energy distribution indicated an effective temperature within 350 of 13850 K, a surface gravity around 3.85, and a microturbulence velocity of 2.5-3.5 km/sec. Normal C and Si abundances were present, along with overabundances of Mg, S, and Fe. Significant overabundances of P, Mn, Ga, Sr, Y, Zr, Eu, and Hg were detected. It is suggested that alpha And has a circumstellar envelope, indicating an unstable atmosphere and mass loss.

Derman, I. E.

1982-11-01

27

Spectroscopic studies of copper enzymes  

SciTech Connect

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

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

1986-05-01

28

Spectroscopic chemical analysis methods and apparatus  

NASA Technical Reports Server (NTRS)

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

29

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

30

Quadrupole resonance spectroscopic study of narcotic materials  

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

31

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

32

FT-IR, FT-Raman, dispersive Raman, NMR spectroscopic studies and NBO analysis of 2-Bromo-1H-Benzimidazol by density functional method  

NASA Astrophysics Data System (ADS)

In this study, geometrical optimization, FT-IR (4000-400 cm-1), FT-Raman (4000-40 cm-1), dispersive Raman (4000-40 cm-1) spectroscopic analysis, electronic structure and 1H and 13C nuclear magnetic resonance (NMR) studies of 2-Bromo-1H-Benzimidazol (abbreviated as 2Br1HB) were undertaken by utilizing DFT/B3LYP with 6-311+G(d,p) basis set. The results of the calculations were applied to simulate spectra of the title compound, which show good agreement with observed spectra. Complete vibrational assignments, analysis and correlations of the fundamental modes for 2Br1HB compound were carried out. Stability of the molecule arising from hyperconjugative interactions, charge delocalization was analyzed using natural bond orbital (NBO) analysis. The molecule orbital contributions were studied by using the total density of states (TDOS), partial density of states (PDOS), and overlap population density of states (OPDOS). The electronic properties like HOMO-LUMO energies and molecular electrostatic potential (MEP) analysis were reported. The calculated HOMO and LUMO energies shows that charge transfer interactions take place within the molecule. Mulliken population analysis on atomic charges was also calculated. Good correlation between the experimental 1H and 13C NMR chemical shifts in DMSO solution and calculated gauge-including atomic orbital (GIAO) shielding tensors were found.

Sas, E. B.; Kurt, M.; Karabacak, M.; Poiyamozhi, A.; Sundaraganesan, N.

2015-02-01

33

Spectroscopic Chemical Analysis Methods and Apparatus  

NASA Technical Reports Server (NTRS)

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

Hug, William F.; Reid, Ray D.

2012-01-01

34

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

35

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

36

Spectroscopic Studies of Classical Cepheids.  

NASA Astrophysics Data System (ADS)

The extent and nature of the distortions of the emergent flux spectrum of cepheids due to the effects of the pulsation as a function of period and amplitude are not clearly understood. A multiphase classification study of a sample of 26 cepheids from the southern hemisphere at the relatively high dispersion of 67(ANGSTROM)/mm has been undertaken and complemented with the recent high quality photometric data for Pel (1976) in order to observe the results of increasing period and amplitude of pulsation on the line spectrum. The original framework of such investigations set up by Struve (1944) and Code (1947) has been enlarged upon principally through the use of modern MK standard supergiant sequences. It has been found that, while the spectrum of weak metal lines (in cepheids with periods less than forty days) can always be found to match that of a non-variable supergiant, anomalies in the strengths of the strong metal lines and Balmer H(delta) and H(gamma) lines increase both in number and intensity with increasing period and amplitude. The consequences of this on the line blanketing of the atmosphere are seen to be significant when comparing the color-spectrum relations of different period bins, indicating the inappropriateness of extending intrinsic color relations established with short period variables to the longer period ones. It has also been found that the effects of the amplitude of the pulsation are more directly felt by the atmosphere near the extrema of the physical displacement as evidenced by the sudden widening of the period-spectrum relation at the mid-descending and mid-rising branch phases. Following the suggestions by Sorvari (1974) that the luminosity sensitive OI 7773(ANGSTROM) triplet is responding to the dynamical effects of the pulsation on the atmosphere, a moderate dispersion (27(ANGSTROM)/mm) study of a small sample of cepheids (4) and supergiant standards has been undertaken. It has been found that the strength of this feature throughout the cycle increases continously with increasing period through the supergiant luminosity class sequences, even though the spectrum of the weak metal lines indicates a constant luminosity class.

Gauthier, Robert Paul

37

Selective spectroscopic methods for water analysis  

SciTech Connect

This dissertation explores in large part the development of a few types of spectroscopic methods in the analysis of water. Methods for the determination of some of the most important properties of water like pH, metal ion content, and chemical oxygen demand are investigated in detail. This report contains a general introduction to the subject and the conclusions. Four chapters and an appendix have been processed separately. They are: chromogenic and fluorogenic crown ether compounds for the selective extraction and determination of Hg(II); selective determination of cadmium in water using a chromogenic crown ether in a mixed micellar solution; reduction of chloride interference in chemical oxygen demand determination without using mercury salts; structural orientation patterns for a series of anthraquinone sulfonates adsorbed at an aminophenol thiolate monolayer chemisorbed at gold; and the role of chemically modified surfaces in the construction of miniaturized analytical instrumentation.

Vaidya, B.

1997-06-24

38

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

39

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

PubMed

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

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

2012-11-01

40

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

41

Study on the interactions of trans-resveratrol and curcumin with bovine ?-lactalbumin by spectroscopic analysis and molecular docking.  

PubMed

The ability of bovine ?-lactalbumin (BLA) as a whey protein to carry curcumin and trans-resveratrol as two natural polyphenolic compounds was investigated by fluorescence quenching measurements and docking studies. Curcumin is the bioactive component of turmeric and trans-resveratrol is abundant in different types of fruits and vegetables. The binding parameters such as binding constants and the number of substantive binding sites have been estimated from the analysis of fluorescence quenching measurements. The differences in affinities of curcumin and trans-resveratrol for BLA were compared. The short Förster's distance (r) between donor (BLA) and acceptor (curcumin and trans-resveratrol) and also the binding constant values demonstrated the strong interaction between these two polyphenolic compounds and BLA. The thermodynamic parameters were obtained from the fluorescence quenching measurements in different temperatures. It can be concluded from the sign and magnitude of ?H and ?S that the final ligand-protein complexes were stabilized by hydrogen bonds. The considerable change in microregion of the Trp residues in BLA is observed upon the binding of the trans-resveratrol to BLA by synchronous fluorescence while this conformation alteration was not observed upon interaction with curcumin. It was indicated by docking studies that curcumin come closer to the Trp-118 than to other tryptophans and trans-resveratrol binds in the vicinity of Trp-60 and Trp-104. Docking studies indicated that these two compounds bind to BLA by two hydrogen bonds. The calculated distances between bound ligands and tryptophans obtained by docking studies were in agreement with fluorescence resonance energy transfer results. Therefore, the strong interaction of curcumin and trans-resveratrol with BLA was confirmed by theoretical and experimental studies. These achieved results may be applicable in the milk industry and drug formulation. PMID:25746281

Mohammadi, Fakhrossadat; Moeeni, Marzieh

2015-05-01

42

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.

2012-06-26

43

Study of optoelectronic energy bands and molecular energy levels of tris (8-hydroxyquinolinate) gallium and aluminum organometallic materials from their spectroscopic and electrochemical analysis  

Microsoft Academic Search

For the purpose of investigating electro-molecular absorption bands, energy gaps, Eg and molecular energy levels (ionization potential, IP and electron affinity, EA) of tris (8-hydroxyquinolinate) gallium and aluminum, spectral analysis in conjunction with electrochemical measurements was carried out. UV–Vis–NIR and FTIR spectroscopic measurements were used to assign the electronic and molecular absorption bands in both of the materials. The XRD

Fahmi Fariq Muhammad; Ali Imran Abdul Hapip; Khaulah Sulaiman

2010-01-01

44

Multi-spectroscopic analysis and molecular modeling on the interaction of curcumin and its derivatives with human serum albumin: a comparative study.  

PubMed

The comparative study about the interaction between curcumin and its derivatives (demothxycurcumin and bisdeoxycurcumin) with human serum albumin (HSA) has been carried out using multi-spectroscopic analysis and molecular modeling method. The characteristic of fluorescence quenching and the thermodynamic parameters have been studied by state emission fluorescence experiments under different temperatures with an interval of 6 K. Curcumin shows largest quenching constant and bisdeoxycurcumin shows the smallest at the temperature of 298 K. However, the quenching constant of curcumin drops quickly with the increase of temperature. Demothxycurcumin gives the largest quenching efficiency at the temperature of 310 K. An average distance of 6.7 nm for energy transfer has been determined based on förster resonance energy theory (FRET). The site competitive replacement experiments illustrate three compounds mainly binding on site I (Subdomain IIA) of the protein, and show tendency of binding on site II (Subdomain IIIA) with the removing of methoxyl groups. Circular dichroism spectra and Fourier transform infrared spectroscopy (FTIR) have been used to investigate the influence on protein secondary structure. Content of the ?-helix increases at low concentrations of the compounds, while unfolding occurs at high concentrations. Docking simulation reveals possible mechanism for different quenching behavior and binding sites preferred by three compounds. The binding modes have effectively supported the conclusion of the experiments. PMID:24491667

Ge, Yu-Shu; Jin, Cheng; Song, Zhe; Zhang, Jia-Qi; Jiang, Feng-Lei; Liu, Yi

2014-04-24

45

Fourier transform infrared spectroscopic study of truffles  

NASA Astrophysics Data System (ADS)

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

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

2006-01-01

46

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

47

Spectroscopic Analysis of Algol during Eclipse Cycle  

NASA Astrophysics Data System (ADS)

Algol, within the Perseus constellation, is referred to as the Winking Demon Star due to its varying apparent magnitude and its representation of the Gorgon Medusa. Every 68.75 hours its light dims suddenly, and brightens again over a ten-hour period. Further observation shows a small dip in light output halfway in between the large dips, indicating that Algol is an eclipsing binary star system. Detailed inspection of the spectrum indicates that Algol is also a spectroscopic binary. Algol consists of a 3 solar diameter B8V star and a 3.5 solar diameter K0IV in very close orbit around each other. This project investigated the spectral characteristics of Algol A and B during the primary eclipse cycle. Low-resolution spectroscopy of the eclipse cycle was imaged over several nights in order to investigate any changes in the emission line profile of the star system. This work lays the foundation for future studies in low-resolution spectroscopy of the Algol and Algol-type systems.

Boyd, Jonathan; Darling, Kodiak; Sparks, Elise; West, Lajeana; Walker, Douglas

2012-05-01

48

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.

Oakland Discovery Center

2011-01-01

49

Spectroscopic study of solar twins and analogues  

NASA Astrophysics Data System (ADS)

Context. Many large stellar surveys have been and are still being carried out, providing huge amounts of data, for which stellar physical parameters will be derived. Solar twins and analogues provide a means to test the calibration of these stellar catalogues because the Sun is the best-studied star and provides precise fundamental parameters. Solar twins should be centred on the solar values. Aims: This spectroscopic study of solar analogues selected from the Geneva-Copenhagen Survey (GCS) at a resolution of 48 000 provides effective temperatures and metallicities for these stars. We test whether our spectroscopic parameters, as well as the previous photometric calibrations, are properly centred on the Sun. In addition, we search for more solar twins in our sample. Methods: The methods used in this work are based on literature methods for solar twin searches and on methods we developed in previous work to distinguish the metallicity-temperature degeneracies in the differential comparison of spectra of solar analogues versus a reference solar reflection spectrum. Results: We derive spectroscopic parameters for 148 solar analogues (about 70 are new entries to the literature) and verify with a-posteriori differential tests that our values are well-centred on the solar values. We use our dataset to assess the two alternative calibrations of the GCS parameters; our methods favour the latest revision. We show that the choice of spectral line list or the choice of asteroid or time of observation does not affect the results. We also identify seven solar twins in our sample, three of which are published here for the first time. Conclusions: Our methods provide an independent means to differentially test the calibration of stellar catalogues around the values of a well-known benchmark star, which makes our work interesting for calibration tests of upcoming Galactic surveys. Based on observations made with ESO Telescopes at the La Silla Observatory under programme ID 077.D-0525 and 090.D-0133.Table 1 is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/A124Full Table 5 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/574/A124

Datson, Juliet; Flynn, Chris; Portinari, Laura

2015-02-01

50

Spectroscopical studies on the structural organization of the lectin discoidin I: analysis of sugar- and calcium-binding activities.  

PubMed

One of the common characteristics observed in different families of sugar-binding proteins is the presence of aromatic residues in the proximity of the functional sugar-binding site (Quiocho, F. (1986) Annu. Rev. Biochem. 55, 287-315). This general property has made these proteins a very appropriate subject for studies using intrinsic fluorescence assays. In the present report we have studied the sugar binding activity of the lectin discoidin I, using a fluorescence-monitored titration assay. The galactose binding has been estimated, with an affinity constant of 1.8.10(-7) M-1 in the absence of calcium. In the presence of 1 mM Ca2+, the Kd of galactose binding is lowered to 2.7.10(-8) M-1. Calcium binding, by itself, seems to occur as two components with Kd values of 10(-7) and 10(-6) M-1. From these data, and sequence comparison of discoidin I with other lectins, a general model for ligand binding has been proposed in which a sequence from position 176 to 188, together with another region close to an apolar tryptophan residue, most probably Trp-50, would participate in the calcium- and sugar-binding site(s) of this protein. PMID:2914150

Valencia, A; Pestaña, A; Cano, A

1989-01-27

51

High Resolution Spectroscopic Study of Abell 78  

NASA Astrophysics Data System (ADS)

High resolution spectroscopic data of the central knots and the outer shell of the planetary nebula Abell 78 are analyzed. Chemical abundances and kinematics were derived for each region. The inner knots appear to be denser and slightly cooler than the outer shell, and they are constituted by an extremely H-deficient material. These knots are receding from the central star with velocities in the range from +40 to -60 km s-1 and present cometary structures probably caused by the stellar wind. The outer shell appears to have very low metallicity but we conclude that abundance determinations are probably affected by large temperature fluctuations in the gas, caused by additional heating mechanisms such as shocks by high speed ejecta and photo-electrons from dust grains, etc. Our kinematical analysis clearly demonstrates that H lines are not emitted in the inner knots but in the outer shell. In the outer zone we have detected a high-velocity compact structure, with velocities from -40 to 90 km s-1. This spike emits in collisionally excited lines (mainly [O III]), but it is not detected in H or He lines. Therefore, it should consist of a ``bullet'' of H-deficient material that is colliding with the outer shell.

Medina, S.; Peña, M.

2000-10-01

52

A Photometric and Spectroscopic Study of Dwarf and Giant Galaxies in the Coma Cluster. II. Spectroscopic Observations  

Microsoft Academic Search

This is the second paper in a series studying the photometric and spectroscopic properties of galaxies of different luminosities in the Coma Cluster. We present the sample selection, spectroscopic observations, and completeness functions. To study the spectral properties of galaxies as a function of their local environment, two fields were selected for spectroscopic observations to cover both the core (Coma

Bahram Mobasher; Terry J. Bridges; Dave Carter; Bianca M. Poggianti; Y. Komiyama; N. Kashikawa; M. Doi; M. Iye; S. Okamura; M. Sekiguchi; K. Shimasaku; M. Yagi; N. Yasuda

2001-01-01

53

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

54

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

55

Spectroscopic study of natural quartz samples  

NASA Astrophysics Data System (ADS)

In this work we performed a spectroscopic characterization of natural amethyst, citrine, and prasiolite samples from different localities. These materials were examined by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV-vis), electron paramagnetic resonance (EPR), and inductively coupled plasma atomic emission spectrometry (ICP-AES). Samples were used in this study in as-received, gamma-irradiated, UV-irradiated, and heat-treated conditions. We observed the changes in the FTIR, UV-vis, and EPR spectra of these samples as a function of the condition they were analyzed. We noticed that gamma radiation had a great effect on the color of amethyst and citrine samples used in this work. It was observed that light colored samples showed a deepening of their colors upon gamma-irradiation and a bleaching upon heat treatment at 450 °C. However, we observed that gamma radiation had a slight effect on the color of citrine. UV-irradiations revealed that the coloration of both amethyst and prasiolite can be bleached by UV radiation. On the other hand, the color of citrine was not affected by UV radiation.

Nunes, Eduardo H. M.; Lameiras, Fernando S.; Houmard, Manuel; Vasconcelos, Wander L.

2013-09-01

56

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

57

Spectroscopic studies of tantalum doped borate glasses  

NASA Astrophysics Data System (ADS)

Glasses with formula 30Li2O 60B2O3xTa2O5 (10-x) Bi2O3 for x=0, 2, 4, 6 and 8 were prepared via normal melt quenching technique and characterized by refractive index and MDSC. Refractive index (?) and glass transition temperature (Tg) are found to increase with increase in dopant concentration. Impedance spectra of the samples were recorded in the frequency range 100 Hz-5 MHz in the temperature range 175-275 °C. The plots are typical of those recorded for disordered systems. Conductivities and relaxation times are found to follow Arrhenius type of relation and activation energies are calculated. Optical absorption spectra were recorded in the wavelength range 200-900 nm range from which cutoff wavelength (?c) and optical band gap energy (Eg) are evaluated. ?c is found to decrease while Eg to increase with increase in composition. FTIR spectra of the samples were recorded in the frequency range 400-1500 cm-1 which exhibit characteristic bands corresponding to BO3, BO4 stretching vibrations and BO bending vibration. Tightening of the structure is indicated by increase in the vibration of BO3 at the cost of BO4 for 8 mol% of Ta2O5. This is in support of the highest value of Tg for this sample among the series. Raman spectra of the samples were recorded in the frequency range 200-1200 cm-1. With successive addition of Ta2O5, increase in the vibration of Ta-O groups TaO6 groups to be responsible for observed increase in ? and Tg. An attempt is made to prepare tantalum doped borate glasses and study them by spectroscopic techniques.

Sharada, M.; Suresh Babu, D.

2012-10-01

58

Spectroscopic analysis of cinnamic acid using quantum chemical calculations.  

PubMed

In this present study, FT-IR, FT-Raman, (13)C NMR and (1)H NMR spectra for cinnamic acid have been recorded for the vibrational and spectroscopic analysis. The observed fundamental frequencies (IR and Raman) were assigned according to their distinctiveness region. The computed frequencies and optimized parameters have been calculated by using HF and DFT (B3LYP) methods and the corresponding results are tabulated. On the basis of the comparison between computed and experimental results assignments of the fundamental vibrational modes are examined. A study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by HF and DFT methods. The alternation of the vibration pattern of the pedestal molecule related to the substitutions was analyzed. The (13)C and (1)H NMR spectra have been recorded and the chemical shifts have been calculated using the gauge independent atomic orbital (GIAO) method. The Mulliken charges, UV spectral analysis and HOMO-LUMO analysis of have been calculated and reported. The molecular electrostatic potential (MEP) was constructed. PMID:25315873

Vinod, K S; Periandy, S; Govindarajan, M

2015-02-01

59

A quantum mechanical/molecular dynamics/mean field study of acrolein in aqueous solution: Analysis of H bonding and bulk effects on spectroscopic properties  

NASA Astrophysics Data System (ADS)

A novel molecular dynamics methodology recently proposed by our group [Rega et al., Chem. Phys. Lett. 422, 367 (2006)], which is based on an integrated hybrid potential rooted in high level quantum mechanical methods using localized basis functions and nonperiodic boundary conditions, has been applied to study acrolein in aqueous solution. The solute structural rearrangement and its hydrogen-bonding pattern due to the interactions with water have been analyzed in some detail. Moreover, the solvent effects on the UV n ??? vertical transition and on the NMR C13 and O17 shielding constants of acrolein have been investigated theoretically by performing a posteriori quantum mechanical calculations on a statistically significant number of snapshots extracted from both gas-phase and aqueous solution simulations. Results show that such effective computational strategy can be successfully used to improve our understanding, at atomic level, of important spectroscopic observables.

Brancato, Giuseppe; Rega, Nadia; Barone, Vincenzo

2006-10-01

60

Analysis of Urinary Calculi Using Infrared Spectroscopic Imaging  

NASA Astrophysics Data System (ADS)

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

Sablinskas, Valdas; Lesciute, Daiva; Hendrixson, Vaiva

2009-06-01

61

Atazanavir-induced urine crystals demonstrated by infrared spectroscopic analysis.  

PubMed

Atazanavir sulfate, an azapeptide inhibitor of HIV protease, has been associated with urolithiasis. A 60-year-old man with atazanavir-induced urinary sediment crystals verified by infrared spectroscopic analysis is described. He had been receiving highly active antiretroviral therapy (HAART) for HIV infection and also had a history of urinary lithiasis and been undergoing urinalysis once every month. Needle-shaped crystals were seen in his urine sediment and infrared spectroscopic analysis revealed that these were atazanavir crystals. Because the presence of the crystals in urine do not always reveal an abnormality in the urinary test strip analysis, the urinary sediment needed to be observed microscopically in order to prevent future urolithiasis and renal failure in this HIV patient receiving atazanavir. © 2013 S. Karger AG, Basel. PMID:24334974

Inagaki, Isao; Adachi, Mariko; Ito, Hiroyasu; Yasuda, Mitsuru; Tsurumi, Hisashi; Deguchi, Takashi; Seishima, Mitsuru

2015-01-01

62

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

63

Raman spectroscopic study of "The Malatesta": a Renaissance painting?  

PubMed

Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research. PMID:25194320

Edwards, Howell G M; Vandenabeele, Peter; Benoy, Timothy J

2015-02-25

64

Raman spectroscopic study of “The Malatesta”: A Renaissance painting?  

NASA Astrophysics Data System (ADS)

Raman spectroscopic analysis of the pigments on an Italian painting described as a 'Full Length Portrait of a Gentleman', known also as the 'Malatesta', and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research.

Edwards, Howell G. M.; Vandenabeele, Peter; Benoy, Timothy J.

2015-02-01

65

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

66

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

67

Type Ia SN1999cw: photometric and spectroscopic study  

E-print Network

The preliminary analysis of the optical data of SN1999cw show that this object has the photometric and spectroscopic behavior of a Type Ia supernova similar to SN1991T, reaching an apparent magnitude at maximum B(max)=14.30 and a Delta m_{15}(B)=0.94.

F. Bufano; M. Turatto; S. Benetti; A. Harutyunyan; N. Elias-Rosa; E. Cappellaro; .

2004-10-20

68

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

69

A SPECTROSCOPIC ANALYSIS OF WHITE DWARFS IN THE KISO SURVEY  

SciTech Connect

We present a spectroscopic analysis of white dwarfs found in the Kiso survey. Spectroscopic observations at high signal-to-noise ratio have been obtained for all DA and DB stars in the Kiso Schmidt ultraviolet excess survey (KUV stars). These observations led to the reclassification of several KUV objects, including the discovery of three unresolved DA+DB double-degenerate binaries. The atmospheric parameters (T{sub eff} and log g) are obtained from detailed model atmosphere fits to optical spectroscopic data. The mass distribution of our sample is characterized by a mean value of 0.606 M{sub sun} and a dispersion of 0.135 M{sub sun} for DA stars, and 0.758 M{sub sun} and a dispersion of 0.192 M{sub sun} for DB stars. Absolute visual magnitudes obtained from our spectroscopic fits allow us to derive an improved luminosity function for the DA and DB stars identified in the Kiso survey. Our luminosity function is found to be significantly different from earlier estimates based on empirical photometric calibrations of M{sub V} for the same sample. The results for the DA stars now appear entirely consistent with those obtained for the PG survey using the same spectroscopic approach. The space density for DA stars with M{sub V} {<=} 12.75 is 2.80 x 10{sup -4} pc{sup -3} in the Kiso survey, which is 9.6% smaller than the value found in the PG survey. The completeness of both surveys is briefly discussed.

Limoges, M.-M.; Bergeron, P., E-mail: limoges@astro.umontreal.c, E-mail: bergeron@astro.umontreal.c [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada)

2010-05-10

70

Infrared Spectroscopic Analysis of Urinary Tract Stones  

Microsoft Academic Search

B Baacckkggrroouunndd.. Urinary tract stones are common urological disorders. However, there have been few studies of the stone composition in Central Taiwan. Infrared spectroscopy is a simple procedure used to analyze urinary stones. We conducted this study to evaluate the composition of urinary tract stones using infrared spectroscopy. M Meetthhooddss.. Most of the samples (89.8%) were obtained during endourological procedures

Chien-Hsing Lu; Hsueh-Fu Lu; Wen-Chi Chen; Tracy Lee; Hsi-Chin Wu

71

FERRE: A Code for Spectroscopic Analysis  

NASA Astrophysics Data System (ADS)

FERRE is a data analysis code written in FORTRAN90. It matches models to data, taking a set of observations and identifying the model parameters that best reproduce the data, in a chi-squared sense. Model predictions are to be given as an array whose values are a function of the model parameters, i.e. numerically. FERRE holds this array in memory, or in a direct-access binary file, and interpolates in it to evaluate model predictions. The code returns, in addition to the optimal set of parameters, their uncertainties, covariances, and the corresponding model prediction. The code is used at the core of the APOGEE Stellar Parameters and Chemical Abundances Pipeline, and it is now publicly available.

Allende-Prieto, Carlos; Apogee Team

2015-01-01

72

Spectroscopic analysis of automotive engine oil  

NASA Astrophysics Data System (ADS)

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

Dahmani, Rachid; Gupta, Neelam

2002-02-01

73

Spatially Resolved Far-Infrared Spectroscopic Analysis of Planetary Nebulae  

NASA Astrophysics Data System (ADS)

Planetary Nebulae (PNs) are late-life intermediate-mass (1-8 solar mass) stars that have shed their outer layers. A wide variety of morphologies and physical conditions is seen in PNs, but a complete understanding of what causes these various conditions is still needed. Spatially resolved far-infrared spectroscopic analysis has been performed on 11 targets using both PACS and SPIRE instruments on the Herschel Space Observatory as part of the Herschel Planetary Nebula Survey (HerPlaNS). Far-IR lines probe the ionized parts of the nebulae and suffer less extinction than optical lines, so observations in the far-IR are critical to our complete understanding of PNs. Because PNs are extended objects, the spectral mapping capabilities of both PACS and SPIRE allow us to better understand the spatial variations of the objects by tracking line strengths as a function of location within the nebula. The far-IR lines detected in this study can be used as tracers of electron density and electron temperature which are critical parameters in radiative transfer modeling of PNs. Information on atomic, ionic, and molecular lines identified in these 11 targets will be presented.

Rattray, Rebecca; Ueta, Toshiya

2015-01-01

74

Parallel multithread computing for spectroscopic analysis in optical coherence tomography  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

75

Spectroscopic Studies of Double Beta Decays and MOON  

SciTech Connect

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

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

2007-10-12

76

Spectroscopic Analysis of Unbound Asteroid Pairs  

NASA Astrophysics Data System (ADS)

We have begun a survey of the asteroids in these pairs to determine whether they share a similar composition, expected if they have originated from the same parent body. We have conducted optical, low-resolution spectroscopy of the asteroids in several unbound pairs. Observations were obtained in January and March 2011 using the 3.6m NTT+EFOSC2 covering the wavelength range 0.4- 0.95 microns, and in May 2011 using the 4.2m WHT+ACAM, covering the wavelength range 0.5- 0.95 microns. The observations of the components in each pair were kept as consistent as possible to reduce spurious effects introduced to the spectra. For example, the same solar analog was observed to remove the solar spectrum from the spectra of each component. Chi-squared fitting of the extracted spectra to the Bus-DeMeo taxonomy [1] allowed taxonomic classifications to be assigned to each asteroid. A chi-squared test was then used to determine the similarity of the spectra of the asteroids in each pair. Initial results suggest that the asteroids in the unbound pair (7343) Ockeghem - (154634) 2003 XX38 exhibit an S-type spectrum. The spectra of these asteroids are excellent matches, with the same spectral slope and apparent silicate-absorption band depth. This information will allow us to use further optical and thermal observations obtained using the Palomar Observatory 200" Hale Telescope and 8m VLT to conduct a thorough dynamical analysis to further constrain the likely formation time of these objects. We will also present the optical spectra of several other unbound pairs obtained during recent observations using the 4.2m WHT and the 8m VLT.

Duddy, S. R.; Lowry, S. C.; Wolters, S. D.; Rozitis, B.; Green, S. F.; Christou, A.; Weissman, P.

2011-10-01

77

Nonlinear spectroscopic studies of chiral media  

SciTech Connect

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

Belkin, Mikhail Alexandrovich

2004-05-20

78

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

79

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

80

A spectroscopic and photometric study of the interacting binary and double period variable HD 170582  

NASA Astrophysics Data System (ADS)

We present a spectroscopic and photometric study of the interacting binary and Double Period Variable HD 170582 based on the analysis of the ASAS V-band light curve and our high-resolution spectra mostly obtained with CHIRON spectrograph at the 1.5m CTIO telescope.

Mennickent, R. E.; Djuraševi?, G.; Cabezas, M.; Cséki, A.; Rosales, J.; Niemczura, E.; Araya, I.; Curé, M.

2015-01-01

81

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

PubMed

A systematic vibrational spectroscopic assignment and analysis of piracetam [(2-oxo-1-pyrrolidineacetamide)] have been carried out using FT-IR and FT-Raman spectral data. The vibrational analysis was aided by an electronic structure calculation based on the hybrid density functional method B3LYP using a 6-311G++(d,p) basis set. Molecular equilibrium geometries, electronic energies, IR and Raman intensities, and harmonic vibrational frequencies have been computed. The assignments are based on the experimental IR and Raman spectra, and a complete assignment of the observed spectra has been proposed. The UV-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies and the maximum absorption wavelengths ?max were determined by the time-dependent DFT (TD-DFT) method. The geometrical parameters, vibrational frequencies and absorption wavelengths were compared with the experimental data. The complete vibrational assignments are performed on the basis of the potential energy distributions (PED) of the vibrational modes in terms of natural internal coordinates. The simulated FT-IR, FT-Raman, and UV spectra of the title compound have been constructed. Molecular docking studies have been carried out in the active site of piracetam by using Argus Lab. In addition, the potential energy surface, HOMO and LUMO energies, first-order hyperpolarizability and the molecular electrostatic potential have been computed. PMID:24487180

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

2014-04-01

82

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

83

Spectroscopic analysis of ferrite doped with different rare earth elements  

Microsoft Academic Search

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

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

2002-01-01

84

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

PubMed

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

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

2008-06-01

85

IR spectroscopic analysis of the new organic silver complex C13H13N4OAg  

NASA Astrophysics Data System (ADS)

IR analysis in the frequency range 400-4000 cm-1 is used here to investigate the changes in different modes of thermally treated new metal complex (diphenyl carbazide silver complex DPCAg, C13H13N4OAg) during the glass transition at 91 °C and the high temperature phase transition at 167 °C. These two phase transitions in this new metal compound are studied here by detecting the changes in some IR spectroscopic parameters (e.g., mode shift, band contour, peak height and peak intensity) during the elevation of temperature. All of the vibrations of DPCAg were found to be due to ionic fundamentals 3311 cm-1, 3097 cm-1, 3052 cm-1, 1677 cm-1, 1602 cm-1, 1492 cm-1, 1306 cm-1, 1252 cm-1, 887 cm-1 and 755 cm-1. The results obtained can be considered as the first spectroscopic analysis of this new metal complex. These results strongly confirmed that the thermally treated DPCAg transverse a glass transition at 91 °C and a high temperature phase transition at 167 °C. Anomalous spectroscopic changes near the glass transition temperature Tg could be recorded. A temperature dependence of peak intensity of the two modes 810 cm-1 and 3440 cm-1 could be observed beyond Tg. Also, the high temperature phase modification at 167 °C showed anomalous change in the spectroscopic parameters before and after the phase transition process. A proposed silver position in the new silver complex DPCAg has been presented.

El-Kabbany, F.; Taha, S.; Hafez, M.

2013-07-01

86

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

87

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

88

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

89

Quantum chemical studies on molecular structure, spectroscopic (IR, Raman, UV-Vis), NBO and Homo-Lumo analysis of 1-benzyl-3-(2-furoyl) thiourea.  

PubMed

Vibrational and electronic spectra for 1-benzyl-3-(2-furoyl) thiourea were calculated by using density functional method (B3LYP) with different basis sets. The complete assignment of all vibrational modes was performed on basis of the calculated frequencies and comparing with the reported IR and Raman spectra for that thiourea derivative. UV-visible absorption spectra of the compound dissolved in methanol were recorded and analyzed using time dependent density functional theory (TD-DFT). The calculated values for the geometrical parameters of the title compound are consistent with the ones reported from XRD studies. The stability of the molecule, related to hyper-conjugative interactions, and electron delocalization were evaluated using natural bond orbital (NBO) analysis. Intra-molecular interactions were studied by AIM approach. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. Molecular electrostatic potential map was performed by the DFT method. PMID:25801444

Gil, Diego M; Defonsi Lestard, M E; Estévez-Hernández, O; Duque, J; Reguera, E

2015-06-15

90

Nondestructive analysis of ancient Egyptian funerary relics by Raman spectroscopic techniques  

Microsoft Academic Search

The non-destructive Raman spectroscopic analysis of a range of ancient Egyptian funerary artefacts has been undertaken with a view to establish the identification of the pigment composition and nature of the interaction with the substrate. The specimens date from the New Kingdom to the Graeco-Roman period, ca. 3900–1800 years b.p. In this study a comparison has also been effected between

Howell G. M. Edwards; Susana E. Jorge Villar; A. Rosalie David; Dalva L. A. de Faria

2004-01-01

91

Spectroscopic and Electrical Analysis of Capacitively Coupled VHF plasma at Atmospheric Pressure for Plasma CVM process  

Microsoft Academic Search

Plasma CVM (Chemical Vaporization Machining) process using atmospheric VHF plasma is developed and have been studied in recent years. It is required to optimize the characterization of such plasma. In this poster, we report the experimental results of spectroscopic and electrical analysis of VHF dischrges in mixed gas (He\\/CF_4\\/O_2) used in CVM process. The total gas pressure is one atmosphere,

Shoichi Kawashima; Yasushi Oshikane; Kenichi Takemoto; Kazuya Yamamura; Katsuyoshi Endo; Yuzo Mori

2001-01-01

92

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

93

Spectroscopic analysis of vermicompost for determination of nutritional quality  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

94

Comparison of two infrared spectroscopic methods for cheese analysis.  

PubMed

Two infrared spectroscopic methods, optothermal near infrared (NIR) spectroscopy and Fourier transform mid-infrared-attenuated total reflection (FTIR-ATR) spectroscopy, were applied to 24 cheese samples in order to obtain protein, fat and moisture contents. Reference values of the protein, fat and moisture contents in weight percent were obtained using standard wet chemistry analysis. Prediction correlation coefficients between 0.93 and 0.96 and standard errors of prediction between 2% and 5% were obtained using optothermal spectroscopy while the corresponding values for FTIR-ATR were 0.81-0.92 and 4-9%. Inhomogeneities in the cheeses, primarily due to the fat droplets, are probably the main reason for the differences in the error sizes. The superior results for optothermal spectroscopy are the more attractive because the instrument is easier to use than the FTIR-ATR instrument, it provides results more quickly with simpler statistical analysis and it is more compact and robust. PMID:18966444

McQueen, D H; Wilson, R; Kinnunen, A; Jensen, E P

1995-12-01

95

Raman spectroscopic studies in supercritical water  

SciTech Connect

Reaction studies have been carried out on the destruction of nitrogen-containing compounds such as ammonium, nitrates, and species containing aromatic nitro functionality. The destruction of ammonium ion in near-critical and supercritical water using Raman spectroscopy is the subject of this presentation. Reaction rates were determined from Raman spectra and from measurements of system pressure. Concentrations of key species in the reactor effluent were determined via off-line assay. The effects of temperature, pressure, and concomitants on reaction rate were determined. The reaction half-life is below ten seconds at 400 C with better than 95% conversion. Oxides of nitrogen were not generated in detectable quantities. The studied system is a model for the destruction of ammonium in municipal wastes.

Bowman, L.E.; Fulton, J.L.

1994-10-01

96

Laser ion source for nuclear spectroscopic studies  

SciTech Connect

An element selective laser ion source has been used to produce beams of exotic radioactive nuclei and to study their decay properties. The operational principle of the ion source is based on selective resonant laser ionization of nuclear reaction products thermalized and neutralized in a noble gas at high pressure. The ion source has been installed at the mass separator (LISOL) which is coupled on line to the cyclotron accelerator at Louvain-la-Neuve. Exotic nickel and cobalt nuclei were produced in proton-induced fission of {sup 238}U. The {beta} decay of {sup 68-74}Ni and {sup 67-70}Co isotopes has been studied by means of {beta}-{gamma} and {gamma}-{gamma} spectroscopy.

Kudryavtsev, Yuri; Andreyev, Andrej; Bruyneel, Bart; Franchoo, Serge; Gentens, Johnny; Huyse, Mark; Kruglov, Kirill; Mueller, Wilhelm; Raabe, Riccardo; Reusen, Ils; Bergh, Paul van den; Duppen, Piet van; Roosbroeck, Jan van; Vermeeren, Ludo; Weissman, Leonid [Instituut voor Kern-en Stralingsfysika, K. U. Leuven Celestijnenlaan 2000 D, B-3001 Leuven (Belgium)

1998-12-16

97

Benzamidoximes: structural, conformational and spectroscopic studies. I  

NASA Astrophysics Data System (ADS)

The synthesis and properties of seven arylamidoximes are reported. 1H- and 13C-NMR studies and MO calculations were performed on all seven and an X-ray crystallographic determination was done on one, to determine their structure. The theoretical calculations were done using the AM1 and PM3 methods. From these results it is concluded that, for all of the arylamidoximes studied here, the NH 2 group of the amidoxime ( N-hydroxyamidine) has very little sp 2 character and the aryl ring is not coplanar with the amidoxime group. X-ray crystallographic data for p-chlorobenzamidoxime were compared with the theoretically calculated coordinates. It is interesting to note that, in crystals, the -NH 2 group is coplanar with the C?N bond and the aryl ring is out of the plane of the amidoxime group. Molecular mechanics (Biosym) calculations on benzamidoxime yielded better coordinates than either the AM1 or PM3 methods.

Srivastava, Rajendra M.; Brinn, Ira M.; Machuca-Herrera, Juan O.; Faria, Herbert B.; Carpenter, Gene B.; Andrade, Djalma; Venkatesh, Chittur G.; F. de Morais, Lécia P.

1997-04-01

98

Integrated Spectroscopic Studies of Hydrous Sulfate Minerals  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

99

Progress report on nuclear spectroscopic studies  

SciTech Connect

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

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

1994-02-18

100

A photometric and spectroscopic study of dwarf and giant galaxies in the Coma cluster - II. Spectroscopic observations  

E-print Network

This is the second paper in a series studying the photometric and spectroscopic properties of galaxies of different luminosities in the Coma cluster. The sample selection, spectroscopic observations and completeness functions are presented here. To study the spectral properties of galaxies as a function of their local environment, two fields were selected for spectroscopic observations to cover both the core (Coma1) and outskirts (ie. south-west of the core and centered on NGC4839)- (Coma3) of the cluster. Medium resolution spectroscopy (6-9 \\AA) was carried out for a total of 490 galaxies in both fields (302 in Coma1 and 188 in Coma3), using the WYFFOS multi-fiber spectrograph on the William Herschel Telescope. The galaxies cover a range of $12 2. The completeness functions for the spectroscopic sample is presented.

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

2001-07-19

101

Nonlinear spectroscopic studies of interfacial molecular ordering  

SciTech Connect

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

Superfine, R.

1991-07-01

102

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

103

Nonlinear spectroscopic studies of interfacial molecular ordering  

NASA Astrophysics Data System (ADS)

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

Superfine, R.

1991-07-01

104

Synthesis, structure, spectroscopic studies (FT-IR, FT-Raman and UV), normal coordinate, NBO and NLO analysis of salicylaldehyde p-chlorophenylthiosemicarbazone  

NASA Astrophysics Data System (ADS)

The thiosemicarbazone compound, salicylaldehyde p-chlorophenylthiosemicarbazone (abbreviated as SCPTSC) was synthesized by refluxing equimolar amounts of 4-(4-methyl phenyl)-3-thiosemicarbazide and salicylaldehyde in presence of one drop of conc. H2SO4 in ethanolic medium for one hour and recrystallised from alcohol. The SCPTSC was characterized by FT-IR, FT-Raman, UV spectroscopy and thermal analysis. By using density functional theory (DFT) using B3LYP method with 6-31+G(d,p) and 6-311++G(d,p) basis sets, molecular geometry and vibrational frequencies were calculated and compared with the experimental data. The detailed interpretation of the vibrational spectra was carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The electronic dipole moment (?D) and the first hyperpolarizability (?tot) values of the investigated molecule were computed by using DFT/B3LYP method with 6-31+G(d,p) and 6-311++G(d,p) basis sets. The stability and charge delocalization of the title molecule were studied by natural bond orbital (NBO) analysis. Mulliken population analysis on atomic charges is also calculated. The molecule orbital contributions were investigated by using the total density of states (TDOS), sum of ? and ? electron density of states (??DOS). Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures were calculated.

Muthu, S.; Elamurugu Porchelvi, E.; Karabacak, M.; Asiri, A. M.; Swathi, Sushmita S.

2015-02-01

105

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

106

Spectroscopic ellipsometry data analysis: Measured vs. calculated quantities  

SciTech Connect

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

Jellison, G.E. Jr.

1997-05-01

107

Spectroscopic and quantum chemical studies on bromopyrazone  

NASA Astrophysics Data System (ADS)

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.

Gökce, Halil; Bahçeli, Semiha

2014-12-01

108

Spectroscopic studies of silver boro tellurite glasses  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

109

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

110

Spectroscopic studies of silver boro tellurite glasses  

SciTech Connect

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

Kumar, E. Ramesh, E-mail: apparao.bojja@gmail.com; Kumari, K. Rajani, E-mail: apparao.bojja@gmail.com; Rao, B. Appa, E-mail: apparao.bojja@gmail.com; Bhikshamaiah, G., E-mail: apparao.bojja@gmail.com [Department of Physics, Osmania University, Hyderabad-500007 (India)

2014-04-24

111

Electrochemical Impedance Spectroscopic Study of Polythiophenes on Carbon Materials  

Microsoft Academic Search

This review article focuses on electrochemical impedance spectroscopic study of thiophenes on carbon materials, the importance of which has been realized by recent progress in literature. The review article has 3 separate sections. In the first part, most of the thiophene derivatives (thiophene, 3-methylthiphene, 3-hexylthiophene, 3,4-ethylenedioxythiophene, 3,4-propylenedioxythiophene, bithiophene, octylthiophene, 3-dodecylthiophene, 3-terthiophene, 3-phenylthiophene, 3-methoxythiophene) and copolymers of thiophenes have been reviewed.

Murat Ates; A. Sezai Sarac

2011-01-01

112

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

113

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

114

Photoelectron spectroscopic studies of 5-halouracil anions  

SciTech Connect

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

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

2011-01-07

115

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

116

Metamictization of zircon: Raman spectroscopic study  

NASA Astrophysics Data System (ADS)

Raman spectroscopy of radiation-damaged natural zircon samples shows increased line broadening and shifts of phonon frequencies with increasing radiation dose. Stretching and bending frequencies of SiO4 tetrahedra soften dramatically with increasing radiation damage. The frequency shifts can be used to determine the degree of radiation damage. Broad spectral bands related to Si-O stretching vibrations between 900 and 1000 cm-1 were observed in metamict/amorphous zircon. The radiation-dose-independent spectral profiles and the coexistence of this broad background and relative sharp Raman modes in partially damaged samples indicate that these bands are correlated with amorphous domains in zircon. The spectral profiles of metamict zircon suggest that in comparison with silica, the SiO4 tetrahedra are less polymerized in metamict zircon. This study also shows that ZrO2 and SiO2 are not the principal products of metamictization in zircon. No indication of bulk chemical unmixing of zircon into ZrO2 and SiO2 was found in 26 samples with a large variation of radiation damage (maximum dose: 23.5 × 1018 icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> -events g-1 ). Only one sample showed clearly, in all measured sample areas, extra sharp lines at 146, 260, 312, 460 and 642 cm-1 characteristic of tetragonal ZrO2 . The geological (and possibly artificial heating) history of this sample is not known. It is concluded that radiation damage without subsequent high temperature annealing does not cause unmixing of zircon into constituent oxides.

Zhang, Ming; Salje, Ekhard K. H.; Farnan, Ian; Graeme-Barber, Ann; Daniel, Philippe; Ewing, Rodney C.; Clark, Andrew M.; Leroux, Hugues

2000-02-01

117

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

PubMed Central

The influence of metal salt on sugar consumption by suspension cells in food models constructed by a sugar and salt aqueous solution was investigated based on mid-infrared spectroscopic analysis. The contaminated suspension cells in the food model could be detected using the spectral feature change that measured the present spectrum subtracted in the initial spectrum. The cells were prepared for growth and although the cell did not grow under the induction period, the cell activation (start of sugar metabolism) was detected on the subtracted spectral behavior before the cell growth. The rough grasp of the spectral change behavior is useful for the high-throughput spectroscopic method to detect the contaminated cell activation. Furthermore, the detailed sugar consumption kinetics of the cells was also investigated based on the spectroscopic method. The kind of added salt in the food model influenced the cell activation and the potassium ions play an important role in the plant cells. The living cells activity in fresh food may act to prevent microbial contamination and to suppress the growth of the contaminated microorganism. Both the simple and detailed analyses based on the spectroscopic method presented in this study might be useful for risk management of food. PMID:24490105

Kameoka, Takaharu; Hashimoto, Atsushi

2013-01-01

118

Effects of essential oil treatments on the secondary protein structure of Vicia faba: A mid-infrared spectroscopic study supported by two-dimensional correlation analysis  

NASA Astrophysics Data System (ADS)

In this study we investigated the effects of essential oil treatments on the secondary protein structure of the Vicia faba roots, a bioindicator plant, in order to obtain information for the potential allelopathic uses of these oils as alternative to the use of pesticides in agriculture. We tested two mixtures of essential oils consisting of Tween 20-emulsions of tea tree oil (TTO) and Tween 20-emulsion of Clove and Rosemary (GARROM) essential oils respectively at three different oil concentrations each. The molecular modifications caused in Vicia faba by exposure to oil emulsions were investigated by FTIR spectroscopy in diffuse reflectance (DRIFT) mode. We considered the specific Amide I, Amide II and Amide VI bands by ordinary and second derivative spectroscopy and the results showed that both Tween 20-emulsion of GARROM and Tween 20-emulsion of TTO oils cause transitions among the secondary (?-helix, ?-sheet and ?-turn) structures with in addition the appearance of random coil structures in exposed samples. The Amide VI bands, placed between 500 and 600 cm-1, confirmed the structural transitions observed for the Amide I bands. In addition we observed the presence of a protein oxidation effect for TTO treated samples, oxidation which resulted negligible instead for the GARROM oil samples. At last, FTIR spectra were also submitted to two-dimensional correlation analysis (2DCORR) and double two-dimensional correlation analysis (D2DCORR); the results confirmed the different effects caused by the two typologies of essential oils on the secondary protein structures of Vicia faba roots.

Mecozzi, Mauro; Sturchio, Elena

2015-02-01

119

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

120

Spectroscopic investigation (FT-IR, FT-Raman), HOMO-LUMO, NBO analysis and molecular docking study of 4-chlorophenyl quinoline-2-carboxylate.  

PubMed

FT-IR and FT-Raman spectra of 4-chlorophenyl quinoline-2-carboxylate 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. Potential energy distribution was done using GAR2PED program. The geometrical parameters obtained theoretically are in agreement with the XRD data. NBO analysis, HOMO-LUMO, first hyperpolarizability and molecular electrostatic potential results are also reported. The calculated hyperpolarizability of the title compound is 77.53 times that of the standard NLO material urea and the title compound and its derivatives are attractive object for future studies of nonlinear optical properties. Molecular docking results suggest that the compound might exhibit inhibitory activity against GPb. PMID:25791883

Fazal, E; Panicker, C Yohannan; Varghese, Hema Tresa; Nagarajan, S; Sudha, B S; War, Javeed Ahamad; Srivastava, S K; Harikumar, B; Anto, P L

2015-06-15

121

Time Resolved Photometric and Spectroscopic Analysis of Chemically Peculiar Stars  

NASA Astrophysics Data System (ADS)

Here we present the report on the ``Nainital-Cape survey'' research project aiming to search for and study the pulsational variability of main-sequence chemically peculiar (CP) stars. For this study, the time-series photometric observations of the sample stars were carried out at the 1.04 m ARIES telescope (India), while the high-resolution spectroscopic and spectro-polarimetric observations were carried out at the the 6.0 m Russian telescope. Under this project, we have recently found clear evidence of photometric variability in the Am star HD 73045, which is likely to be pulsating in nature with a period of about 36 min, hence adding a new member to the family of the ? Scuti pulsating variables that have peculiar abundances.

Joshi, Santosh; Joshi, Gireesh C.; Joshi, Y. C.; Aggrawal, Rahul

2015-01-01

122

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

123

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

Microsoft Academic Search

IR spectroscopic studies are reported for N-stearyl-d-erythro-phytosphingosine (Cer NP) and N-stearyl-2-hydroxy-d-erythro-phytosphingosine (Cer AP) in a hydrated model of the skin lipid barrier comprised of equimolar mixtures of each ceramide with cholesterol and d35-stearic acid. Examination of the methylene stretching, rocking and bending modes reveal some rotational freedom and hexagonal packing in both the ceramide and stearic acid chains. Analysis of

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

2005-01-01

124

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

125

Effects of essential oil treatments on the secondary protein structure of Vicia faba: a mid-infrared spectroscopic study supported by two-dimensional correlation analysis.  

PubMed

In this study we investigated the effects of essential oil treatments on the secondary protein structure of the Vicia faba roots, a bioindicator plant, in order to obtain information for the potential allelopathic uses of these oils as alternative to the use of pesticides in agriculture. We tested two mixtures of essential oils consisting of Tween 20-emulsions of tea tree oil (TTO) and Tween 20-emulsion of Clove and Rosemary (GARROM) essential oils respectively at three different oil concentrations each. The molecular modifications caused in Vicia faba by exposure to oil emulsions were investigated by FTIR spectroscopy in diffuse reflectance (DRIFT) mode. We considered the specific Amide I, Amide II and Amide VI bands by ordinary and second derivative spectroscopy and the results showed that both Tween 20-emulsion of GARROM and Tween 20-emulsion of TTO oils cause transitions among the secondary (?-helix, ?-sheet and ?-turn) structures with in addition the appearance of random coil structures in exposed samples. The Amide VI bands, placed between 500 and 600 cm(-1), confirmed the structural transitions observed for the Amide I bands. In addition we observed the presence of a protein oxidation effect for TTO treated samples, oxidation which resulted negligible instead for the GARROM oil samples. At last, FTIR spectra were also submitted to two-dimensional correlation analysis (2DCORR) and double two-dimensional correlation analysis (D2DCORR); the results confirmed the different effects caused by the two typologies of essential oils on the secondary protein structures of Vicia faba roots. PMID:25203214

Mecozzi, Mauro; Sturchio, Elena

2015-02-25

126

Spectroscopic analysis of the open 3d subshell transition metal aluminides: AIV, AICr, and AlCo  

E-print Network

Spectroscopic analysis of the open 3d subshell transition metal aluminides: AIV, AICr, and Al The present study of AlV, AlCr, and AlCo is a continu- ation of the study of the 3d transition metal element, Al, and the atoms of the 3d transition metal series. Specific chemical bonding considerations

Morse, Michael D.

127

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

128

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

129

Spectroscopic investigation (FT-IR, FT-Raman and SERS), vibrational assignments, HOMO-LUMO analysis and molecular docking study of Opipramol  

NASA Astrophysics Data System (ADS)

FT-IR and FT-Raman spectra of Opipramol were recorded and analyzed. SERS spectrum was recorded in silver colloid. The vibrational wave numbers were computed using DFT quantum chemical calculations. The data obtained from wave number calculations are used to assign vibrational bands obtained in infrared and Raman spectra as well as in SERS of the studied molecule. Potential energy distribution was done using GAR2PED program. The geometrical parameters (DFT) of the title compound are in agreement with the XRD results. The presence of CH2 stretching modes in the SERS spectrum indicates the close of piperazine ring with the metal surface and the interaction of the silver surface with this moiety. NBO analysis, HOMO-LUMO, first hyperpolarizability and molecular electrostatic potential results are also reported. The inhibitor Opipramol forms a stable complex with P4502C9 as is evident from the ligand-receptor interactions and a -9.0 kcal/mol docking score and may be an effective P4502C9 inhibitor if further biological explorations are carried out.

Mary, Y. Sheena; Panicker, C. Yohannan; Kavitha, C. N.; Yathirajan, H. S.; Siddegowda, M. S.; Cruz, Sandra M. A.; Nogueira, Helena I. S.; Al-Saadi, Abdulaziz A.; Van Alsenoy, Christian; War, Javeed Ahmad

2015-02-01

130

Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid  

NASA Astrophysics Data System (ADS)

In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

2015-02-01

131

Ultraviolet spectroscopic studies of Seyfert 1 galaxies and quasars  

NASA Astrophysics Data System (ADS)

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

Doddamani, Vijayakumar H.

132

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

133

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  

NASA Astrophysics Data System (ADS)

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.

Saravanan, S.; Balachandran, V.

2014-09-01

134

Exploring AGN Unification through Mid-Infrared Spectroscopic Analysis  

NASA Astrophysics Data System (ADS)

The emission of silicate dust and species of low- and high-ionization dominate the mid-infrared (MIR) spectra of active galactic nuclei (AGN). The dust, expected to be in a toroidal distribution about a central, supermassive black hole, may or may not obscure optical broad-line emission emanating from within, providing the type 2 and type 1 AGN classes, respectively. In the context of AGN unification, type 1 and 2 AGN may inherently be similar objects which are distinguished by the viewing angle of the observer. Many avenues have been explored to decipher AGN unification, or the lack thereof. We present the findings of a two method approach analyzing an archival sample of AGN observed by the Infrared Spectrograph aboard the Spitzer Space Telescope. The first approach implements MIR spectral energy distributions to determine the arrangement of dust within the torus and if there are similarities between the AGN classes. The second is a comparative analysis of prominent MIR ionization lines between the two AGN classes. We also discuss implications of the star formation present in the MIR spectroscopic observations and their potential influence on the premise of AGN unification.

Thompson, Grant D.; Macnamara, Murray E.

2015-01-01

135

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

NASA Astrophysics Data System (ADS)

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

Reid, Piper

2013-01-01

136

Spectroscopic study of Er:Sm doped barium fluorotellurite glass.  

PubMed

In this paper, we report the physical and spectroscopic properties of Er(3+), Sm(3+) and Er(3+):Sm(3+) ions codoped barium fluorotellurite (BFT) glasses. Different Stokes and anti-Stokes emissions were observed under 532 nm and 976 nm laser excitations. Energy transfer from Er(3+) ion to Sm(3+) ion was confirmed on the basis of luminescence intensity variation and decay curve analysis in both the cases. Under green (532 nm) excitation emission intensity of Sm(3+) ion bands improves whereas on NIR (976 nm) excitation new emission bands of Sm(3+) ions were observed in Er:Sm codoped samples. Ion interactions and the different energy transfer parameters were also calculated. PMID:20510646

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

2010-09-15

137

DFT electronic structure calculations, spectroscopic studies, and normal coordinate analysis of 2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl acetate.  

PubMed

The solid phase FTIR and FT-Raman spectra of 2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl acetate (25N2LCPA) have been recorded 450-4000cm(-1) and 100-4000cm(-1) respectively. The normal coordinate analysis was carried out to confirm the precision of the assignments. DFT calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies and IR intensities. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31+G(d,p) basis set. The detailed interpretation of the vibrational spectra has been carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The Vibrational frequencies are calculated in the above method and are compared with experimental frequencies which yield good agreement between observed and calculated frequencies. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. In addition, Frontiers molecular orbital and molecular electrostatic potential were computed by using Density Functional Theory (DFT) B3LYP/6-31+G(d,p) basis set. The calculated HOMO and LUMO energies show that charge transfer occurs in the molecule. PMID:25544190

Muthu, S; Elamuruguporchelvi, E; Varghese, Anitha

2015-03-01

138

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

NASA Astrophysics Data System (ADS)

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

Obali, Aslihan Yilmaz; Ucan, Halil Ismet

2015-02-01

139

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

140

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

141

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

142

A Planetary Environment and Analysis Chamber Equipped with Multiple Spectroscopic Sensors  

NASA Astrophysics Data System (ADS)

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

Sobron, P.; Wang, A.

2010-03-01

143

In vivo analysis of burns in a mouse model using spectroscopic optical coherence tomography.  

PubMed

Spectroscopic analysis of biological tissues can provide insight into changes in structure and function due to disease or injury. Depth-resolved spectroscopic measurements can be implemented for tissue imaging using optical coherence tomography (OCT). Here, spectroscopic OCT is applied to in vivo measurement of burn injury in a mouse model. Data processing and analysis methods are compared for their accuracy. Overall accuracy in classifying burned tissue was found to be as high as 91%, producing an area under the curve of a receiver operating characteristic curve of 0.97. The origins of the spectral changes are identified by correlation with histopathology. PMID:25360936

Maher, Jason R; Jaedicke, Volker; Medina, Manuel; Levinson, Howard; Selim, Maria Angelica; Brown, William J; Wax, Adam

2014-10-01

144

In vivo analysis of burns in a mouse model using spectroscopic optical coherence tomography  

PubMed Central

Spectroscopic analysis of biological tissues can provide insight into changes in structure and function due to disease or injury. Depth resolved spectroscopic measurements can be implemented for tissue imaging using optical coherence tomography (OCT). Here spectroscopic OCT is applied to in vivo measurement of burn injury in a mouse model. Data processing and analysis methods are compared for their accuracy. Overall accuracy in classifying burned tissue was found to be as high as 91%, producing an area under the curve of a receiver operator characteristic curve of 0.97. The origins of the spectral changes are identified by correlation with histopathology. PMID:25360936

Maher, Jason R.; Jaedicke, Volker; Medina, Manuel; Levinson, Howard; Selim, Maria Angelica; Brown, William J.; Wax, Adam

2015-01-01

145

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

PubMed

Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples. PMID:15766067

Meng, Yu-Fei; Peng, Ming-Sheng

2004-07-01

146

Electron spectroscopic studies of perfect and defect metal oxide surfaces  

NASA Astrophysics Data System (ADS)

A number of surface sensitive electron spectroscopic techniques have been used during the last few years to study the geometric and electronic structure of well characterized surfaces of metal oxide single crystals. For rocksalt monoxides, the (100) surface has been found to be very nearly a truncation of the bulk lattice; only qualitative low energy electron diffraction (LEED) measurements have been performed on other oxide crystal structures. The electronic structure of nearly perfect oxide surfaces is generally very similar to that of the bulk, although excitonic surface states have been found on some rocksalt oxides. However, the presence of O-vacancy point defects on transition metal oxide surfaces changes their electronic structure drastically, increasing the d-orbital population of the cations adjacent to the defect. These surface defects are generally the active sites for chemisorption, with nearly perfect surfaces being relatively inert with respect to most of the molecules that have been studied.

Henrich, Victor E.

1987-09-01

147

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

148

DFT studies on antioxidant mechanisms, electronic properties, spectroscopic (FT-IR and UV) and NBO analysis of C-glycosyl flavone, an isoorientin  

NASA Astrophysics Data System (ADS)

The relationship between structure and electronic properties of isoorientin, a C-glycoside flavone is investigated to relate its radical scavenging activity using molecular descriptors. To elucidate the antioxidant activity of polyphenolics, three mechanisms namely hydrogen atom transfer (HAT), single electron transfer-proton transfer (SET-PT) and sequential proton-loss electron-transfer (SPLET) are employed. In gas-phase, Osbnd H bond dissociation enthalpies (BDE), ionization potential (IP), proton dissociation enthalpies (PDE), proton affinity (PA) and electron transfer enthalpy (ETE) are computed and correlated relevant to antioxidant potency of the title compound employing DFT/6-311G(d,p) protocol. The theoretically simulated FT-IR and the UV-visible absorption spectra have been compared with the experimental data. Based on the absorbed UV spectra and TD-DFT calculations, assignment of the absorption bands are carried out. In addition, formation of intramolecular hydrogen bond and most possible interaction sites are explained by using natural bond orbital (NBO) analysis.

Deepha, V.; Praveena, R.; Sadasivam, K.

2015-02-01

149

Vibrational spectroscopic (FTIR and FT Raman) studies, first order hyperpolarizabilities and HOMO, LUMO analysis of p-toluenesulfonyl isocyanate using ab initio HF and DFT methods.  

PubMed

The Fourier transform infrared (FTIR) and FT Raman spectra of p-toluenesulfonyl isocyanate (p-tosyl isocyanate) have been measured. 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 FTIR and FT Raman data. The thermodynamic functions of the title compound were also performed with the aid of HF/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory. Simulated FTIR and FT Raman spectra for p-tosyl isocyanate showed good agreement with the observed spectra. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The dipole moment (?), polarizability (?) and the hyperpolarizability (?) values of the investigated molecule have been computed using HF and B3LYP methods. PMID:21795105

Parimala, K; Balachandran, V

2011-10-15

150

Spectroscopic analysis of small organic molecules: a comprehensive near-edge x-ray-absorption fine-structure study of C6-ring-containing molecules.  

PubMed

We report high-resolution C 1s near-edge x-ray-absorption fine-structure (NEXAFS) spectra of the C6-ring-containing molecules benzene (C6H6), 1,3- and 1,4-cyclohexadiene (C6H8), cyclohexene (C6H10), cyclohexane (C6H12), styrene (C8H8), and ethylbenzene (C8H10) which allow us to examine the gradual development of delocalization of the corresponding pi electron systems. Due to the high experimental resolution, vibrational progressions can be partly resolved in the spectra. The experimental spectra are compared with theoretical NEXAFS spectra obtained from density-functional theory calculations where electronic final-state relaxation is accounted for. The comparison yields very good agreement between theoretical spectra and experimental results. In all cases, the spectra can be described by excitations to pi*- and sigma*-type final-state orbitals with valence character, while final-state orbitals of Rydberg character make only minor contributions. The lowest C 1s-->1pi* excitation energy is found to agree in the (experimental and theoretical) spectra of all molecules except for 1,3-cyclohexadiene (C6H8) where an energy smaller by about 0.6 eV is obtained. The theoretical analysis can explain this result by different binding properties of this molecule compared to the others. PMID:16438578

Kolczewski, C; Püttner, R; Martins, M; Schlachter, A S; Snell, G; Sant'anna, M M; Hermann, K; Kaindl, G

2006-01-21

151

Vibrational spectroscopic (FT-IR and FT-Raman) studies, natural bond orbital analysis and molecular electrostatic potential surface of Isoxanthopterin.  

PubMed

The FTIR and FT-Raman spectra of Isoxanthopterin have been recorded in the region 4000-450 and 4000-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of Isoxanthopterin were obtained by the density functional theory (DFT) using 6-311++G(d,p) basis set. The harmonic vibrational frequencies were scaled and compared with experimental values. The observed and the calculated frequencies are found to be in good agreement. The (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were also calculated using the gauge independent atomic orbital (GIAO) method. The UV-visible spectrum was also recorded and compared with the theoretical values. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The first order hyperpolarizability (?0), related properties (?, ?0 and ??) and the Mulliken charges of the molecule were also computed using DFT calculations. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the ?* and ?* antibonding orbitals and second order delocalization energies (E2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. Information about the charge density distribution of the molecule and its chemical reactivity has been obtained by mapping molecular electrostatic potential surface. In addition, the non-linear optical properties were discussed from the dipole moment values and excitation wavelength in the UV-visible region. PMID:23751224

Prabavathi, N; Nilufer, A; Krishnakumar, V

2013-10-01

152

A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies  

ERIC Educational Resources Information Center

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

Ramos, Carlos Henrique I.

2004-01-01

153

Thermal and spectroscopic studies of the antioxidant food additive propyl gallate.  

PubMed

Literature mentions propyl gallate (PG) as a non-toxic synthetic antioxidant that can be used as a food additive due to its high tolerance to heat. It is important to understand the thermal properties and to identify the decomposition products of this substance, since it has been reported to be thermally stable at temperatures as high as 300°C. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry-photovisual (DSC-photovisual), coupled thermogravimetry-infrared spectroscopy (TG-FTIR) analyses and spectroscopic techniques were used to study the food additive PG. The TG-DTA curves, which were performed with the aid of DSC-photovisual, provided information concerning the thermal stability and decomposition profiles of the compound. From the TG-FTIR coupled techniques, it was possible to identify n-propanol as a possible volatile compound released during the thermal decomposition of the antioxidant. A complete spectroscopic characterization in the ultraviolet, visible, near and middle infrared regions was performed in order to understand the spectroscopic properties of PG. PMID:25842313

Gálico, D A; Nova, C V; Guerra, R B; Bannach, G

2015-09-01

154

Classification and Identification of Enterococci: a Comparative Phenotypic, Genotypic, and Vibrational Spectroscopic Study  

PubMed Central

Rapid and accurate identification of enterococci at the species level is an essential task in clinical microbiology since these organisms have emerged as one of the leading causes of nosocomial infections worldwide. Vibrational spectroscopic techniques (infrared [IR] and Raman) could provide potential alternatives to conventional typing methods, because they are fast, easy to perform, and economical. We present a comparative study using phenotypic, genotypic, and vibrational spectroscopic techniques for typing a collection of 18 Enterococcus strains comprising six different species. Classification of the bacteria by Fourier transform (FT)-IR spectroscopy in combination with hierarchical cluster analysis revealed discrepancies for certain strains when compared with results obtained from automated phenotypic systems, such as API and MicroScan. Further diagnostic evaluation using genotypic methods—i.e., PCR of the species-specific ligase and glycopeptide resistance genes, which is limited to the identification of only four Enterococcus species and 16S RNA sequencing, the “gold standard” for identification of enterococci—confirmed the results obtained by the FT-IR classification. These results were later reproduced by three different laboratories, using confocal Raman microspectroscopy, FT-IR attenuated total reflectance spectroscopy, and FT-IR microspectroscopy, demonstrating the discriminative capacity and the reproducibility of the technique. It is concluded that vibrational spectroscopic techniques have great potential as routine methods in clinical microbiology. PMID:11325987

Kirschner, C.; Maquelin, K.; Pina, P.; Ngo Thi, N. A.; Choo-Smith, L.-P.; Sockalingum, G. D.; Sandt, C.; Ami, D.; Orsini, F.; Doglia, S. M.; Allouch, P.; Mainfait, M.; Puppels, G. J.; Naumann, D.

2001-01-01

155

FT-IR spectroscopic, thermal analysis of human urinary stones and their characterization  

NASA Astrophysics Data System (ADS)

In the present study, FT-IR, XRD, TGA-DTA spectral methods have been used to investigate the chemical compositions of urinary calculi. Multi-components of urinary calculi such as calcium oxalate, hydroxyl apatite, struvite and uric acid have been studied. The chemical compounds are identified by FT-IR spectroscopic technique. The mineral identification was confirmed by powder X-ray diffraction patterns as compared with JCPDS reported values. Thermal analysis techniques are considered the best techniques for the characterization and detection of endothermic and exothermic behaviors of the urinary stones. The percentages of each hydrate (COM and COD) are present together, in the presences of MAPH or UA. Finally, the present study suggests that the Urolithiasis is significant health problem in children, and is very common in some parts of the world, especially in India. So that present study is so useful and helpful to the scientific community for identification of latest human health problems and their remedies using spectroscopic techniques.

Selvaraju, R.; Raja, A.; Thiruppathi, G.

2015-02-01

156

FT-IR spectroscopic, thermal analysis of human urinary stones and their characterization.  

PubMed

In the present study, FT-IR, XRD, TGA-DTA spectral methods have been used to investigate the chemical compositions of urinary calculi. Multi-components of urinary calculi such as calcium oxalate, hydroxyl apatite, struvite and uric acid have been studied. The chemical compounds are identified by FT-IR spectroscopic technique. The mineral identification was confirmed by powder X-ray diffraction patterns as compared with JCPDS reported values. Thermal analysis techniques are considered the best techniques for the characterization and detection of endothermic and exothermic behaviors of the urinary stones. The percentages of each hydrate (COM and COD) are present together, in the presences of MAPH or UA. Finally, the present study suggests that the Urolithiasis is significant health problem in children, and is very common in some parts of the world, especially in India. So that present study is so useful and helpful to the scientific community for identification of latest human health problems and their remedies using spectroscopic techniques. PMID:25306135

Selvaraju, R; Raja, A; Thiruppathi, G

2015-02-25

157

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

158

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2-acetoxybenzoic acid by density functional methods  

NASA Astrophysics Data System (ADS)

In this work, colorless crystals of 2-acetoxybenzoic acid were grown by slow evaporation method and the FT-IR and FT-Raman spectra of the sample were recorded in the region 4000-500 cm-1 and 4000-100 cm-1 respectively. Molecular structure is optimized with the help of density functional theory method (B3LYP) with 6-31+G(d,p), 6-311++G(d,p) basis sets. 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 confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis following the scaled quantum mechanical force field (SQMFF) methodology. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. Mulliken population analysis on atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule.

Bhavani, K.; Renuga, S.; Muthu, S.; Sankara narayanan, K.

2015-02-01

159

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

ERIC Educational Resources Information Center

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

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

2014-01-01

160

Spectroscopic Studies of Colloidal Solutions of Nanocrystalline Ru(bpy)3 2+-Zeolite Y  

E-print Network

Spectroscopic Studies of Colloidal Solutions of Nanocrystalline Ru(bpy)3 2+-Zeolite Y Norma B of Ru(bpy)3 2+-zeolite Y has made it possible to use conventional optical transmission spectroscopic methods to examine the entrapped Ru(bpy)3 2+ species within the zeolite. To prepare the suspensions

Dutta, Prabir K.

161

Spectroscopic study of sorption of nitrogen heterocyclic compounds on phyllosilicates  

SciTech Connect

The present study focused on understanding the sorption characteristics of acridine (AcN) and acridine-9-carboxylic acid (AcNCOOH), two typical nitrogen heterocyclic compounds (NHCs), on well-characterized phyllosilicates (hectorite, saponite, and muscovite). Results presented in this article show that the degree of sorption of NHCs on phyllosilicates was dependent on the nature of the participating sorbates and sorbents. Sorption of the selected NHCs was pH-dependent, with maximum sorption occurring at low pH conditions, especially at pH < pK{sub a} of the NHC. Though sorption of the cationic forms of the NHCs on clays was preferred, neutral, zwitterionic, and anionic species of NHCs also sorbed on the clay surfaces. Spectroscopic studies have shown that sorbed NHC molecules formed clusters on clay surfaces, which acted as templates for molecular aggregation. Finally, the authors have also found that the clay surfaces promoted protonation of neutral AcN molecules at low sorbate concentrations.

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

1999-03-02

162

Spectroscopic Observations and Analysis of the Peculiar SN 1999aa  

Microsoft Academic Search

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

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

2004-01-01

163

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic analysis of regenerated bone  

NASA Astrophysics Data System (ADS)

The cutting of bone is routinely required in medical procedures, especially in dental applications. In such cases, bone regeneration and new bone quality can determine the success of the treatment. This study investigated the main spectral differences of undamaged and healed bone using the ATR-FTIR spectroscopy technique. Three rabbits were submitted to a surgical procedure; a small piece of bone (3x3 mm2) was removed from both sides of their jaws using a high speed drill. After 15 days, the rabbits were euthanized and the jaws were removed. A bone slice was cut from each side of the jaw containing regions of undamaged and newly formed bone, resulting in six samples which were polished for spectroscopic comparison. The samples were analyzed by FTIR spectroscopy using a diamond ATR accessory. Spectral characteristics were compared and particular attention was paid to the proportion of phosphate to amide I bands and the width of the phosphate band. The results show that the ratio of phosphate to amide I is smaller in new bone tissue than in the undamaged bone, indicating a higher organic content in the newly formed bone. The analysis of the width of the phosphate band suggests a crystallinity difference between both tissues, since the width was higher in the new bone than in the natural bone. These results suggest that the differences observed in bone aging processes by FTIR spectroscopic can be applied to the study of healing processes.

Benetti, Carolina; Kazarain, Sergei G.; Alves, Marco A. V.; Blay, Alberto; Correa, Luciana; Zezell, Denise M.

2014-03-01

164

Spectroscopic Analysis and Modeling of the Red Rectangle  

NASA Astrophysics Data System (ADS)

In this dissertation, we study the mass-loss processes of HD 44179, the central object of the Red Rectangle (RR) nebula. HD 44179 is a single-lined spectroscopic binary system, consisting of a post-AGB primary star and a main-sequence secondary star. The binary is obscured from direct view by an optically thick circumbinary disk; therefore, the primary star is observed exclusively via dust scattering over the top of the disk. The majority of this dissertation uses a data set of high-resolution spectra (R = 38,000), acquired with ARCES echelle spectrograph on the 3.5-m telescope at the Apache Point Observatory. The data set contains 33 observations spanning 8 years that provide spectra with good orbital coverage (orbital period 317 d). This dissertation focuses on the study of the Na I D-lines and H?. We use the time variability of these line profiles in order to study the obscured binary system and its outflowing material. The profile of a single Na I D-line in HD 44179 is complex and contains a double-peaked emission line, a blue-shifted absorption, and a periodic red-shifted absorption. In our study of the Na I D-lines, we are able to explain the origin of the single- and double-peaked emission profiles as arising from emitting gas in the extended nebula. We discuss the orbital phase-dependent asymmetric photospheric lines, as well as find an orbital solution from our data set. We are able to explain the periodically appearing red-shifted absorption feature as the broadened Doppler-shifted photospheric absorption line, while the blue-shifted absorption feature is attributed to material outflowing from the system. The H? profile consists of a narrow single-peaked emission, a broader emission plateau, extended emission wings, and a periodically variable blue-shifted absorption. The single-peaked emission originates from an HII region inside the cavity of the circumbinary disk. The broader emission plateau is likely emission from the bipolar jet, which originates from an accretion disk around the secondary star. The extended emission wings could be produced by the accretion disk or in the jet. In the study of the variable nature of the blue-shifted absorption feature, we are able to determine the geometric, kinematic, and density structure of the jet. We constructed a simple geometric model for the jet, approximating it as a bi-cone. We used this model to produce absorption spectra via the Sobolev approximation for comparison to our observations. The observations, along with our simple model, indicate that the biconical (X-shaped) outflows seen in the RR are formed directly via a relatively constant (on the time scale of our observations) wide angle jet, which has a half opening angle nearly equal to the effective line of sight to the primary star.

Thomas, Joshua David

165

Mössbauer spectroscopic studies of hemoglobin and its isolated subunits.  

PubMed Central

Samples of 90% enriched 57Fe hemoglobin and its isolated subunits have been prepared. Mössbauer 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 Mössbauer spectral differences between the HbO2 sites in the alpha subunit sample and the beta subunit sample. The measured Mössbauer 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 HbO2 sites is the smallest. PMID:3708086

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

1986-01-01

166

Spectroscopic studies of R(+)-?-lipoic acid--cyclodextrin complexes.  

PubMed

?-Lipoic acid (ALA) has a chiral center at the C6 position, and exists as two enantiomers, R(+)-ALA (RALA) and S(-)-ALA (SALA). RALA is naturally occurring, and is a cofactor for mitochondrial enzymes, therefore playing a major role in energy metabolism. However, RALA cannot be used for pharmaceuticals or nutraceuticals because it readily polymerizes via a 1,2-dithiolane ring-opening when exposed to light or heat. So, it is highly desired to find out the method to stabilize RALA. The purpose of this study is to provide the spectroscopic information of stabilized RALA and SALA through complexation with cyclodextrins (CDs), ?-CD, ?-CD and ?-CD and to examine the physical characteristics of the resultant complexes in the solid state. The RALA-CD structures were elucidated based on the micro fourier transform infrared (FT-IR) and Raman analyses. The FT-IR results showed that the C=O stretching vibration of RALA appeared at 1717 cm?¹ and then shifted on formation of the RALA-CD complexes. The Raman spectra showed that the S-S and C-S stretching vibrations for RALA at 511 cm?¹ (S-S), 631 cm?¹ (C-S) and 675 cm?¹ (C-S) drastically weakened and almost disappeared upon complexation with CDs. Several peaks indicative of O-H vibrations also shifted or changed in intensity. These results indicate that RALA and CDs form host-guest complexes by interacting with one another. PMID:25387076

Ikuta, Naoko; Tanaka, Akira; Otsubo, Ayako; Ogawa, Noriko; Yamamoto, Hiromitsu; Mizukami, Tomoyuki; Arai, Shoji; Okuno, Masayuki; Terao, Keiji; Matsugo, Seiichi

2014-01-01

167

Spectroscopic Study on the Interaction of 4-dimethylaminochalcones with Phospholipids  

NASA Astrophysics Data System (ADS)

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

Tome?ková, V.; Revická, M.; Sassen, A.; Veliká, B.; Stupák, M.; Perjési, P.

2014-11-01

168

Spectroscopic Studies of R(+)-?-Lipoic Acid—Cyclodextrin Complexes  

PubMed Central

?-Lipoic acid (ALA) has a chiral center at the C6 position, and exists as two enantiomers, R(+)-ALA (RALA) and S(?)-ALA (SALA). RALA is naturally occurring, and is a cofactor for mitochondrial enzymes, therefore playing a major role in energy metabolism. However, RALA cannot be used for pharmaceuticals or nutraceuticals because it readily polymerizes via a 1,2-dithiolane ring-opening when exposed to light or heat. So, it is highly desired to find out the method to stabilize RALA. The purpose of this study is to provide the spectroscopic information of stabilized RALA and SALA through complexation with cyclodextrins (CDs), ?-CD, ?-CD and ?-CD and to examine the physical characteristics of the resultant complexes in the solid state. The RALA-CD structures were elucidated based on the micro fourier transform infrared (FT-IR) and Raman analyses. The FT-IR results showed that the C=O stretching vibration of RALA appeared at 1717 cm?1 and then shifted on formation of the RALA-CD complexes. The Raman spectra showed that the S–S and C–S stretching vibrations for RALA at 511 cm?1 (S–S), 631 cm?1 (C–S) and 675 cm?1 (C–S) drastically weakened and almost disappeared upon complexation with CDs. Several peaks indicative of O–H vibrations also shifted or changed in intensity. These results indicate that RALA and CDs form host-guest complexes by interacting with one another. PMID:25387076

Ikuta, Naoko; Tanaka, Akira; Otsubo, Ayako; Ogawa, Noriko; Yamamoto, Hiromitsu; Mizukami, Tomoyuki; Arai, Shoji; Okuno, Masayuki; Terao, Keiji; Matsugo, Seiichi

2014-01-01

169

Fluorination of graphene: a spectroscopic and microscopic study.  

PubMed

Since the advent of graphene, there has been intense interest in exploring the possibility of incorporating fluorinated graphene (FG), an ultrathin insulator, into graphene electronics as barriers, gate dielectrics, and optoelectronic elements. Here we report on the synthesis of FG from single-layer graphene sheets grown by chemical vapor deposition (CVD) using CF4 plasma. We examine its properties systematically via microscopic and spectroscopic probes. Our studies show that, by controlling the conditions of the plasma, FG of varying fluorine coverage can be produced; however, the resulting material contains a mixture of CFx (x = 1-3) bonds. Existing grain boundaries and lattice defects of CVD graphene play an important role in controlling its rate of fluorination and the damage of the sheet. Combining topography and current mapping, we demonstrate that the spatial distribution of fluorine on CVD graphene is highly inhomogeneous, where multilayer islands and structural features such as folds, wrinkles, and ripples are less fluorinated and consequently form a conductive network through which charge transport occurs. It is the properties of this network that manifest in the electrical transport of FG sheets. Our experiments reveal the many challenges of deriving electronics-quality FG from current CVD graphene while at the same time point to the possible solutions and potential of FG in graphene electronics and optoelectronics. PMID:24471932

Wang, Bei; Wang, Junjie; Zhu, Jun

2014-02-25

170

Spectroscopic study of laser-produced plasmas in hydrogen  

SciTech Connect

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

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

1995-08-01

171

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

172

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

NASA Astrophysics Data System (ADS)

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

Manciu, Felicia

2012-10-01

173

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

NASA Astrophysics Data System (ADS)

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

Isac Paulraj, E.; Muthu, S.

2013-05-01

174

FT-Raman spectroscopic analysis of an Antarctic endolith  

NASA Astrophysics Data System (ADS)

The FT-Raman spectra of an Antarctic endolith from the LTER site at Lake Hoare are reported. The specimen provides an unusual occurrence of endolithic colonization of an igneous rock substratum, which analyses as microcline feldspar. The presence of aragonite in the red biological stratum and calcite in a fissure of the rock which has not been subjected to colonization can be attributed to the penetration of calcareous deposits from shallow ground water in an earlier environment in the Dry Valleys. The green biological layer is composed of chlorophyll and [beta]-carotene. Comparison with previous Raman spectroscopic work on endoliths in sedimentary Beacon sandstone is effected.

Villar, Susana E. Jorge; Edwards, Howell G. M.; Wynn-Williams, David D.; Worland, M. Roger

2002-10-01

175

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

176

Image tube spectroscopic studies of rapid variables. IV - Spectroscopic and photometric observations of AE Aquarii  

NASA Technical Reports Server (NTRS)

Photoelectric and time-resolved spectroscopic observations of the short-period eruptive binary AE Aqr are presented. The system has a period of 0.4116537 days, and emission and absorption-line components equal to 135 km/sec and 159 km/sec, respectively. The spectral type of the absorption-line component is found to be K5V, from which M1 = 0.82 solar mass, M2 = 0.69 solar mass, and i = 64 deg. A predominantly Ca II emission region occurs on the hemisphere of the K5V star facing the broad emission-line component, whose center of light is located 0.64 of the way from the inner Lagrangian point to the center of mass of the K star. This emission appears to be associated with the transfer of mass from the K5V star to the accretion disk surrounding the primary. In the absence of flare activity, the light of the system is variable in the orbital period with a range in V of about 0.16 mag; maxima occurs near the times of maximum recession velocity and during the approach of each of the two components of the system (0.25 P and 0.80 P).

Chincarini, G.; Walker, M. F.

1981-01-01

177

Spectroscopic studies of the unfolding of a multimeric protein ?-crystallin.  

PubMed

?-Crystallin is a multimeric eye lens protein having molecular chaperone-like function which is crucial for lens transparency. The stability and unfolding-refolding properties of ?-crystallin plays important roles for its function. We undertook a multi probe based fluorescence spectroscopic approach to explore the changes in the various levels of organization of this protein at different urea concentration. Steady state fluorescence studies reveal that at 0.6M urea a compact structural intermediate is formed which has a native-like secondary structure with enhanced surface exposure of hydrophobic groups. At 2.8M urea the tertiary interactions are largely collapsed with partial collapse of secondary and quaternary structure. The surface solvation probed by picosecond time resolved fluorescence of acrylodan labeled ?-crystallin revealed dry native-like core of ?-crystallin at 0.6M urea compared to enhanced water penetration at 2.8M urea and extensive solvation at 6M urea. Activation energy for the subunit exchange decreased by 22 kJ mol(-1) on changing urea concentration from 0 to 0.6M compared with over 75 kJ mol(-1) on changing urea concentration from 0 to 2.8M. Light scattering and analytical ultracentrifugation techniques were used to determine size and oligomerization of the unfolding intermediates. The data indicated swelling but no oligomer breakdown at 0.6M urea. At 2.8M urea the oligomeric size is considerably reduced and a monomer is produced at 6M urea. The data clearly reveals that structural breakdown of ?-crystallin does not follow hierarchical sequence as tertiary structure dissolution takes place before complete oligomeric dissociation. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 549-560, 2014. PMID:24122648

Chowdhury, Aritra; Choudhury, Aparajita; Banerjee, Victor; Banerjee, Rajat; Das, K P

2014-05-01

178

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

179

LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY  

EPA Science Inventory

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

180

Spectroscopic studies of cathode materials for lithium-ion batteries  

Microsoft Academic Search

Structural changes that occur during electrochemical cycling of lithium-ion battery cathode materials have been investigated using in situ spectroscopic techniques. A new method was developed for the preparation of carbon and binder free cathodes utilizing powder materials of interest for commercial batteries. The extraordinary quality of the cyclic voltammetric curves recorded for this type of electrodes during the in situ

Dana Alexa Totir

2000-01-01

181

Spectroscopic analysis of DA white dwarfs from the McCook & Sion catalog  

E-print Network

For some years now, we have been gathering optical spectra of DA white dwarfs in an effort to study and define the empirical ZZ Ceti instability strip. However, we have recently expanded this survey to include all the DA white dwarfs in the McCook & Sion catalog down to a limiting visual magnitude of V=17.5. We present here a spectroscopic analysis of over 1000 DA white dwarfs from this ongoing survey. We have several specific areas of interest most notably the hot DAO white dwarfs, the ZZ Ceti instability strip, and the DA+dM binary systems. Furthermore, we present a comparison of the ensemble properties of our sample with those of other large surveys of DA white dwarfs, paying particular attention to the distribution of mass as a function of effective temperature.

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

2008-10-29

182

Chromospheric variations with solar cycle phase using imaging and spectroscopic studies  

NASA Astrophysics Data System (ADS)

Spectroscopic observations of Sun in Ca-K line profile were made as a function of latitude and integrated over the visible 180° longitude at the Kodaikanal observatory since 1985. The spectroheliograms of the Sun in Ca-K line have also been obtained at the observatory since 1907. We have derived Ca-K line parameters such as K1 and K2 widths and K-index averaged over regions 10° in latitude and 180° in longitudes from the spectroscopic studies and plage areas in these regions using the images of the Sun in Ca-K line. The comparison of Ca-K line widths with plage areas in respective latitude belts shows that small-scale activity due to network areas is very important in the study of irradiance variation with solar cycle phase. The K1 and K2 widths and K-index around 60° latitude belt show much less variation almost at the noise level during the solar cycle 22 and 23 as compared to other latitude belts and polar regions. These variations with latitude and time indicate the presence of two types of activity or flows. We infer the presence of counter flows in the polar regions and find that such type of analysis with better resolution and frequent observations will be very useful for solar cycle studies.

Sindhuja, G.; Singh, Jagdev; Priyal, Muthu

2015-04-01

183

Investigation on interaction of prulifloxacin with pepsin: A spectroscopic analysis  

NASA Astrophysics Data System (ADS)

The interaction between prulifloxacin, a kind of new oral taking antibiotic and pepsin, a kind of enzyme in the stomach has been investigated in vitro under a simulated physiological condition by different spectroscopic methods. The intrinsic fluorescence of pepsin was strongly quenched by prulifloxacin. This effect was rationalized in terms of a static quenching procedure. The binding parameters have been evaluated by fluorescence quenching methods. The negative value of ? G0 reveals that the binding process is a spontaneous process. The binding distance R between donor (pepsin) and acceptor (prulifloxacin) was obtained according to the Förster's resonance energy transfer theory and found to be 0.95 nm. The results obtained herein will be of biological significance in pharmacology and clinical medicine.

Huang, Yabei; Yan, Jie; Liu, Benzhi; Yu, Zhang; Gao, Xiaoyan; Tang, Yingcai; Zi, Yanqin

2010-03-01

184

Spectroscopic Analysis of Today's Compact Fluorescent Light Bulbs  

NASA Astrophysics Data System (ADS)

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

Pluhar, Edward

2012-03-01

185

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

186

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

187

Molecular spectroscopic analysis of nano-chitosan blend as biosensor  

NASA Astrophysics Data System (ADS)

Chitosan/starch and chitosan/gelatin of different ratios were prepared following casting method. FTIR results indicate the formation of hydrogen bonding which dedicates the prepared blends for interaction with wide range of molecules specially those of NH 2 and COOH terminals. The results obtained with molecular modeling PM3 model are in agreement with spectroscopic data. As a result of increasing starch and gelatin in chitosan blends HOMO-LUMO energy slightly decreased while total dipole moment increased. UV-vis spectroscopy indicated the suitability of chitosan/starch blend as a glycine sensor. Further enhancement in the sensing performance of chitosan/starch blend was achieved by introducing 5 nm TiO 2 into the blend.

Ibrahim, Medhat; Mahmoud, Abdel Aziz; Osman, Osama; Refaat, Ahmed; El-Sayed, El-Sayed M.

2010-11-01

188

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.

189

HUNTING THE PARENT OF THE ORPHAN STREAM. II. THE FIRST HIGH-RESOLUTION SPECTROSCOPIC STUDY  

E-print Network

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 ...

Casey, Andrew R.

190

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

E-print Network

Solid-State NMR Spectroscopic Study of Phosphate Sorption Mechanisms on Aluminum (Hydr)oxides Wei the mechanism of phosphate sorption on aluminum hydroxides under different environ- mental conditions, including

Sparks, Donald L.

191

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

192

The effect of refluxing on the alkoxide-based sodium potassium niobate sol-gel system: Thermal and spectroscopic studies  

SciTech Connect

A study on the effects of prolonged heating under reflux conditions of up to 70 h on alkoxides of sodium, potassium and niobium dissolved in 2-methoxyethanol for the synthesis of sols of composition Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) has been carried out using combined thermogravimetric-Fourier transform infrared spectroscopic analyses. Extended refluxing increases the homogeneity of the Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) system. Spectroscopic analyses on the non-refluxed and 70 h refluxed NKN gels reveal the existence of inorganic hydrated carbonates and bicarbonates, which we propose arise from the hydration and carbonation of the samples on standing in air. The X-ray diffraction patterns of these two types of gels show orthorhombic NKN phase evolutions at higher temperatures. -- Graphical abstract: Total organic evolution plots over time for NKN dried gels obtained under different refluxing times show different thermochemical behaviours and these were investigated by thermal and spectroscopic analysis tools to find a correlation between the extent of -M-O-M- chain link formation and the amount of solvent vapour (methoxyethanol) evolution. Display Omitted Research highlights: > Prolonged refluxing of sol-gel NKN precursor solutions improves final properties of an NKN system. > An NKN process thermo-chemistry with thermal and spectroscopic analysis tools was explored. > An FTIR of NKN gels reveals tendency of NKN systems for rehydration and recarbonation on standing.

Chowdhury, Anirban, E-mail: anirban.chowdhury@gmail.co [Institute for Materials Research, Houldsworth Building, University of Leeds, Leeds, LS2 9JT (United Kingdom); Bould, Jonathan [Institute for Materials Research, Houldsworth Building, University of Leeds, Leeds, LS2 9JT (United Kingdom); Institute of Inorganic Chemistry, Academy of Science of the Czech Republic, 250 68 Rez (Czech Republic); Londesborough, Michael G.S. [Institute of Inorganic Chemistry, Academy of Science of the Czech Republic, 250 68 Rez (Czech Republic); Milne, Steven J. [Institute for Materials Research, Houldsworth Building, University of Leeds, Leeds, LS2 9JT (United Kingdom)

2011-02-15

193

Spectroscopic study of carbaryl sorption on smectite from aqueous suspension.  

PubMed

Sorption of carbaryl (1-naphthyl-N-methyl-carbamate) from aqueous suspension to smectite was studied using Fourier transform infrared (FTIR), high-performance liquid chromatography (HPLC) (for batch sorption), and quantum chemical methods. The amount of carbaryl sorbed was strongly dependent on the surface-charge density of the smectite with more sorption occurring on the two "low" surface-charge density smectites (SHCa-1 and SWy-2) compared to that of the high surface-charge SAz-1 smectite. In addition, the amount of carbaryl sorbed was strongly dependent on the nature of the exchangeable cation and followed the order of Ba approximately Cs approximately Ca > Mg approximately K > Na approximately Li for SWy-2. A similartrend was found for hectorite (SHCa-1) of Cs > Ba > Ca > K approximately Mg > Na approximately Li. Using the shift of the carbonyl stretching band as an indicator of the strength of interaction between carbaryl and the exchangeable cation, the observed order was Mg > Ca > Ba approximately K > Na > Cs. The position of the carbonyl stretching band shifted to lower wavenumbers with increasing ionic potential of the exchangeable cation. Density functional theory predicted a cation-induced lengthening of the C=O bond, resulting from the carbonyl group interacting directly with the exchangeable cation in support of the spectroscopic observations. Further evidence was provided by a concomitant shift in the opposite direction by several vibrational bands in the 1355-1375 cm(-1) region assigned to stretching bands of the carbamate N-Ccarbonyl and Oether-Ccarbonyl bonds. These data indicate that carbaryl sorption is due, in part, to site-specific interactions between the carbamate functional group and exchangeable cations, as evidenced by the FTIR data. However, these data suggest that hydrophobic interactions also contribute to the overall amount of carbaryl sorbed. For example, the FTIR data indicated thatthe weakest interaction occurred when Cs+ was the exchangeable cation. In contrast, the highest amount of carbaryl sorption was observed on Cs-exchanged smectite. Of all the cations studied, Cs has the lowest enthalpy of hydration. It is suggested that this low hydration energy provides the carbaryl with greater access to the hydrophobic regions of the siloxane surface. PMID:16382933

de Oliveira, Maurilio Fernandes; Johnston, Cliff T; Premachandra, G S; Teppen, Brian J; Li, Hui; Laird, David A; Zhu, Dongqiang; Boyd, Stephen A

2005-12-01

194

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

195

A spectroscopic study of local hyperluminous infrared galaxies  

NASA Astrophysics Data System (ADS)

While IRAS revealed a plethora of ultraluminous infrared galaxies (ULIGs L_IR > 1010 L_solar), the high luminosity component (L_IR > 1013 L_solar) is relatively rare in number. Often selected with techniques biased towards AGN, Hyperluminous infrared galaxies (HyLIGs) are intriguing sources displaying a variety of optical spectroscopic types, and too faint for any meaningful spectroscopic investigation with instruments to date. Their colossal infrared luminosities imply a highly obscured starburst and/or AGN power source where the majority of the4 UV/optical photons are absorbed and re-radiated by dust across the infrared wavelength range. The presence of dust means the galaxy's emission suffers extinction. This is particularly important as it implies optical spectroscopy probes only the unobscured components of these systems. With the advent of the SST, these rare sources are spectroscopically accessible for the first time at the wavelengths where they are bright and suffer from low extinction. Spectroscopic data from the Infrared Space Observatory (ISO) reveal that the mid-infrared is rich with spectral features: continuum and features from a range of dust grains residing in different phases of interstellar matter within a galaxy; subtle absorption features from silicates and water ice and hydrocarbons; and lines originating from ions, atoms and molecules. However HyLIGs were beyond the reach of ISOs sensitivity. With the Spitzer Space Telescope (SST) we may now probe into the constituent media and physical processes occurring within these luminous galaxies, for which our knowledge to date is broadly confined to coarsely sampled SEDs.

Verma, Aprajita; Dieter, Lutz; Lehnert, Matthew; Sturm, Eckhard; Tecza, Matthias

2004-09-01

196

Spectroscopic Analysis of Hydrothermal Alteration in Geothermal Drill Core  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

197

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

198

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

199

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

200

Spectroscopic Analysis of Perfluoropolyether Lubricant Degradation During Boundary Lubrication  

NASA Technical Reports Server (NTRS)

The degradation of a branched perfluoropolyether (PFPE) under boundary lubrication conditions was studied using mu-FTIR and mu-Raman spectroscopies. Stainless steel (440C) discs coated with thin (600A), uniform films of the PFPE were tested in a ball-on-disc apparatus until various levels of friction coefficient were attained. Discs were then examined using the above techniques. When the friction coefficient surpassed the value obtained with an un-lubricated control, the lubricant film had either been physically displaced or partially transformed in to a 'friction polymer'. Infrared analysis of this 'friction polymer' indicated the presence of a polymeric fluorinated acid species (R(sub f)COOH). Raman spectroscopy indicated the presence of amorphous carbon in the wear track and in the friction polymer. Some reaction mechanisms are suggested to explain the results.

Herrera-Fierro, Pilar; Shogrin, Bradley A.; Jones, William R., Jr.

1996-01-01

201

A Detailed Spectroscopic Analysis of The EQ Pegasi System  

NASA Astrophysics Data System (ADS)

EQ Pegasi (GJ 896, HIP 116132 ) is a resolved binary system comprised of mid-M dwarfs at a distance of only 6.2 pc. The system has been studied extensively over a broad range of wavelengths from the X-ray to the radio. These observations reveal both components are variable, flare, and exhibit high levels of magnetic activity. The pair were recently proposed as members of a nearby young kinematic association on the basis of consistent Galactic kinematics, strong X-ray emission, and color-magnitude diagram position. Thus, they may be the closest pre-main-sequence system to the Sun. Here we present a detailed analysis of EQ Peg A and B using medium resolution spectra covering ~0.5-2.5 microns. We investigate spectral types, chromospheric activity indicators, lithium depletion, and gravity sensitive alkali lines and molecular bands to characterize the system and place constraints on its age.

Schlieder, Joshua E.; Murphy, Simon; Riedel, Adric R.

2015-01-01

202

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

203

Spectroscopic ellipsometry (SE) studies on vacuum-evaporated ZnSe thin films  

SciTech Connect

Iodine-doped ZnSe thin films were prepared onto well-cleaned glass substrates using vacuum evaporation technique under a vacuum of 3.4 x 10{sup -3} Pa. The composition, structural, optical and electrical properties of the deposited films were analyzed using Rutherford Backscattered Spectrometry (RBS), X-ray diffraction (XRD), spectroscopic ellipsometry (SE) and I-V characteristics. In the RBS analysis, the composition of the deposited film was calculated as (ZnSe)I{sub 0.003}. The structure of the deposited film was identified as cubic, oriented along the (111) direction. The structural parameters such as particle size, strain and dislocation density values were calculated as 28.28 nm, 1.38 x 10{sup -3} lin{sup -2} m{sup -4} and 1.29 x 10{sup 15} lin/m{sup 2}, respectively. Spectroscopic Ellipsometric (SE) measurements were done on the (ZnSe)I{sub 0.003} thin films. The spectral data showed three distinct critical-point structures, including weak structures at E {sub 0} + {delta} {sub 0}, indicating that the sample has a high crystalline quality. The optical band gap value of the deposited films was calculated as 2.63 eV using optical transmittance measurements. From the I-V characteristics studies, the conduction mechanism was found to be SCLC.

Venkatachalam, S. [Thin film laboratory, Department of Physics, Bharathiar University, Coimbatore - 641046 (India); Soundararajan, D. [Thin film laboratory, Department of Physics, Bharathiar University, Coimbatore - 641046 (India); Peranantham, P. [Thin film laboratory, Department of Physics, Bharathiar University, Coimbatore - 641046 (India); Mangalaraj, D. [Thin film laboratory, Department of Physics, Bharathiar University, Coimbatore - 641046 (India)]. E-mail: dmraj800@yahoo.com; Narayandass, Sa.K. [Thin film laboratory, Department of Physics, Bharathiar University, Coimbatore - 641046 (India); Velumani, S. [Departamento de Fisica, ITESM-Campus, Monterrey, Nuevo Leon, C.P.64849 (Mexico); Schabes-Retchkiman, P. [Instituto de Fisica, Univ. Nal. Autonoma de Mexico, A.P.20-364, C.P.01000, Mexico, D.F. (Mexico)

2007-08-15

204

Spectroscopic observations and analysis of the peculiar SN1999aa  

SciTech Connect

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

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

2003-12-10

205

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

206

Spectroscopic and quantum chemical analysis of Isonicotinic acid methyl ester  

NASA Astrophysics Data System (ADS)

In this present study, an organic compound Isonicotinic acid methyl ester (INAME) was structurally characterized by FTIR, FT-Raman, and NMR and UV spectroscopy. The optimized geometrical parameters and energies of all different and possible conformers of INAME are obtained from Density Functional Theory (DFT) by B3LYP/6-311++G(d,p) method. There are three conformers (SI, SII-1, and SII-2) for this molecule (ground state). The most stable conformer of INAME is SI conformer. The molecular geometry and vibrational frequencies of INAME in the ground state have been calculated by using HF and density functional method (B3LYP) 6-311++G (d,p) basis set. Detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The computed vibrational frequencies were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. A study on the electronic properties, such as HOMO and LUMO energies were performed by time independent DFT approach. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (?) and first hyper polarizability (?) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results show that the INAME molecule may have microscopic nonlinear optical (NLO) behavior with non zero values. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by gauge independent atomic orbital (GIAO) method.

Shoba, D.; Periandy, S.; Govindarajan, M.; Gayathri, P.

2015-02-01

207

Artificial neural networks for plasma x-ray spectroscopic analysis  

Microsoft Academic Search

Modern diagnostic instrumentation produces a vast amount of data that often requires substantial analysis efforts. New methods are needed to improve the efficiency of the analysis process. Artificial neural networks have been applied to a variety of signal processing and image recognition problems. The feed-forward, back-propagation technique is well suited for the analysis of scientific laboratory data, which is viewed

J. T. Larsen; W. L. Morgan; W. H. Goldstein

1992-01-01

208

Spectroscopic analysis of ligand binding to lanthanide-macrocycle platforms.  

PubMed

A high-affinity, binary Eu(3+) receptor site consisting of 1,4,7,10-tetraazacyclododecane-1,7-diacetate (DO2A) was constructed with the goal of improving the detection of dipicolinic acid (DPA), a major component of bacterial spores. Ternary Eu(DO2A)(DPA)(-) complex solutions (1.0 microM crystallographically characterized TBA x Eu(DO2A)(DPA)) were titrated with EuCl3 (1.0 nM-1.0 mM); increased Eu(3+) concentration resulted in a shift in equilibrium population from Eu(DO2A)(DPA)(-) to Eu(DO2A)(+) and Eu(DPA)(+), which was monitored via the ligand field sensitive (5)D0 --> (7)F3 transition (lambda(em) = 670-700 nm) using luminescence spectroscopy. A best fit of luminescence intensity titration data to a two-state thermodynamic model yielded the competition equilibrium constant (Kc), which in conjunction with independent measurement of the Eu(DPA)(+) formation constant (Ka) allowed calculation of the ternary complex formation constant (Ka'). With this binding affinity by competition (BAC) assay, we determined that Ka' = 10(8.21) M(-1), which is approximately 1 order of magnitude greater than the formation of Eu(DPA)(+). In general, the BAC assay can be employed to determine ligand binding constants of systems where the lanthanide platform (usually a binary complex) is stable and the ligand bound versus unbound states can be spectroscopically distinguished. PMID:18578548

Kirby, James P; Cable, Morgan L; Levine, Dana J; Gray, Harry B; Ponce, Adrian

2008-08-01

209

Quantitative comparison of analysis methods for spectroscopic optical coherence tomography: reply to comment  

PubMed Central

We reply to the comment by Kraszewski et al on “Quantitative comparison of analysis methods for spectroscopic optical coherence tomography.” We present additional simulations evaluating the proposed window function. We conclude that our simulations show good qualitative agreement with the results of Kraszewski, in support of their conclusion that SOCT optimization should include window shape, next to choice of window size and analysis algorithm. PMID:25401016

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

2014-01-01

210

Micro-Ft Spectroscopic Studies of Breast Tissues  

NASA Astrophysics Data System (ADS)

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

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

211

IR spectroscopic study of the chemical composition of epiphytic lichens  

NASA Astrophysics Data System (ADS)

Changes in the chemical composition of lichens exposed to pollutants are investigated by means of FTIR spectroscopy. According to model experiments, alkyl nitrates, ammonium salts, amines, and sulfones develop in the lichen thallus through the action of ammonia and nitric and sulfuric acids. Spectroscopic data of modeling experiments enabled nitrogen- and sulfur-containing substances to be identified as the main air pollutants in the vicinity of a pig-breeding complex and information to be obtained on the content of the pollutants and their impact on the lichens.

Meysurova, A. F.; Khizhnyak, S. D.; Pakhomov, P. M.

2011-11-01

212

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

213

Spectroscopic and quantum chemical analysis of Isonicotinic acid methyl ester.  

PubMed

In this present study, an organic compound Isonicotinic acid methyl ester (INAME) was structurally characterized by FTIR, FT-Raman, and NMR and UV spectroscopy. The optimized geometrical parameters and energies of all different and possible conformers of INAME are obtained from Density Functional Theory (DFT) by B3LYP/6-311++G(d,p) method. There are three conformers (SI, SII-1, and SII-2) for this molecule (ground state). The most stable conformer of INAME is SI conformer. The molecular geometry and vibrational frequencies of INAME in the ground state have been calculated by using HF and density functional method (B3LYP) 6-311++G (d,p) basis set. Detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The computed vibrational frequencies were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. A study on the electronic properties, such as HOMO and LUMO energies were performed by time independent DFT approach. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (?) and first hyper polarizability (?) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results show that the INAME molecule may have microscopic nonlinear optical (NLO) behavior with non zero values. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by gauge independent atomic orbital (GIAO) method. PMID:25459608

Shoba, D; Periandy, S; Govindarajan, M; Gayathri, P

2015-02-01

214

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

PubMed

IR spectroscopic studies are reported for N-stearyl-D-erythro-phytosphingosine (Cer NP) and N-stearyl-2-hydroxy-D-erythro-phytosphingosine (Cer AP) in a hydrated model of the skin lipid barrier comprised of equimolar mixtures of each ceramide with cholesterol and d(35)-stearic acid. Examination of the methylene stretching, rocking and bending modes reveal some rotational freedom and hexagonal packing in both the ceramide and stearic acid chains. Analysis of the acid carbonyl stretch and the ceramide Amide I modes show both shift to higher frequencies, indicating weaker hydrogen bonding, in the mixed systems compared to the pure materials. For both systems, the fatty acid chain disordering temperatures are significantly increased from those of the pure acids. The observed behaviors of these phytosphingosine ceramide systems are fundamentally different from the previously reported analogous sphingosine ceramide systems. The implications of these observations for lipid organization in the stratum corneum are briefly discussed. PMID:15752463

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

2005-03-01

215

Site-specific tagging proteins via a rigid, stable and short thiolether tether for paramagnetic spectroscopic analysis.  

PubMed

Increasing the stability of protein bioconjugates and improving the resolution of protein complexes is important for spectroscopic analysis in structural biology. The reaction of phenylsulfonated pyridine derivatives and protein thiols generates a stable, rigid and short thiolether tether, which is valuable in high-resolution spectroscopic measurements. PMID:25578486

Yang, Yin; Wang, Jin-Tao; Pei, Ying-Ying; Su, Xun-Cheng

2015-02-01

216

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

217

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

218

Artificial neural networks for plasma x-ray spectroscopic analysis  

SciTech Connect

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

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

1992-10-01

219

Analysis of Spectroscopic Radiation Portal Monitor Data Using Principal Components Analysis  

SciTech Connect

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

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

2006-06-01

220

Chemical and spectroscopic analysis of organic matter transformations during composting of pig manure  

Microsoft Academic Search

Composting of separated pig manure (SPM) was studied in an attempt to elaborate upon organic matter (OM) transformation during the process and define parameters for product maturity using both chemical and spectroscopical methods. Composting was performed in two piles and the following parameters were measured in 10 samples during 122 days of composting: temperature, ash content, C\\/N ratio, water-soluble organic

Jenn-Hung Hsu; Shang-Lien Lo

1999-01-01

221

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

222

Chemical factor analysis of skin cancer FTIR-FEW spectroscopic data  

NASA Astrophysics Data System (ADS)

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

Bruch, Reinhard F.; Sukuta, Sydney

2002-03-01

223

Comment on “Quantitative comparison of analysis methods for spectroscopic optical coherence tomography”  

PubMed Central

In a recent paper by Bosschaart et al. [Biomed. Opt. Express 4, 2570 (2013)] various algorithms of time-frequency signal analysis have been tested for their performance in blood analysis with spectroscopic optical coherence tomography (sOCT). The measurement of hemoglobin concentration and oxygen saturation based on blood absorption spectra have been considered. Short time Fourier transform (STFT) was found as the best method for the measurement of blood absorption spectra. STFT was superior to other methods, such as dual window Fourier transform. However, the algorithm proposed by Bosschaart et al. significantly underestimates values of blood oxygen saturation. In this comment we show that this problem can be solved by thorough design of STFT algorithm. It requires the usage of a non-gaussian shape of STFT window that may lead to an excellent reconstruction of blood absorption spectra from OCT interferograms. Our study shows that sOCT can be potentially used for estimating oxygen saturation of blood with the accuracy below 1% and the spatial resolution of OCT image better than 20 ?m. PMID:25401015

Kraszewski, Maciej; Trojanowski, Micha?; Str?kowski, Marcin R.

2014-01-01

224

Structural and spectroscopic studies of a commercial glassy carbon  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

225

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

226

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

NASA Astrophysics Data System (ADS)

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

Drobek, Dominik; Pigulski, Andrzej

2014-02-01

227

RAMAN SPECTROSCOPIC ANALYSIS OF FERTILIZERS AND PLANT TISSUE FOR PERCHLORATE  

EPA Science Inventory

Raman spectroscopy, without the need for prior chromatographic separation, was used for qualitative and quantitative analysis of 59 samples of fertilizers for perchlorate (ClO4-). These primarily lawn and garden products had no known link to Chile saltpeter, which is known to con...

228

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

229

A spectroscopic study of the cis/trans-isomers of penta-2,4-dienoic acid attached to gold nanoclusters.  

PubMed

In this theoretical work, we present a spectroscopic analysis of the cis/trans-isomers of a molecular switch, penta-2,4-dienoic acid, attached to gold clusters of different size (1, 2 and 20 gold atoms). We have simulated 4 different spectroscopic techniques: Infrared spectroscopy, normal Raman scattering, absorption spectra and resonance Raman scattering. We discuss how the position and the conformation of the molecule determine the electronic structure and hence, the spectra. The calculations have been performed using density functional theory for the properties of the ground state and time-dependent density functional theory for the excited-state properties. Special emphasis is put on the resonance Raman spectra for the study of the isomers. In the present case, resonance Raman scattering is best suited to discriminate between the isomers on the gold clusters. PMID:25594564

Latorre, Federico; Guthmuller, Julien; Marquetand, Philipp

2015-03-11

230

Extensive spectroscopic and photometric study of HD 25558, a long orbital-period binary with two SPB components  

NASA Astrophysics Data System (ADS)

We carried out an extensive photometric and spectroscopic investigation of the SPB binary, HD 25558 (see Fig. 1 for the time and geographic distribution of the observations). The ~2000 spectra obtained at 13 observatories during 5 observing seasons, the ground-based multi-colour light curves and the photometric data from the MOST satellite revealed that this object is a double-lined spectroscopic binary with a very long orbital period of about 9 years. We determined the physical parameters of the components, and have found that both lie within the SPB instability strip. Accordingly, both components show line-profile variations consistent with stellar pulsations. Altogether, 11 independent frequencies and one harmonic frequency were identified in the data. The observational data do not allow the inference of a reliable orbital solution, thus, disentangling cannot be performed on the spectra. Since the lines of the two components are never completely separated, the analysis is very complicated. Nevertheless, pixel-by-pixel variability analysis of the cross-correlated line profiles was successful, and we were able to attribute all the frequencies to the primary or secondary component. Spectroscopic and photometric mode-identification was also performed for several of these frequencies of both binary components. The spectroscopic mode-identification results suggest that the inclination and rotation of the two components are rather different. While the primary is a slow rotator with ~6 d rotation period, seen at ~60° inclination, the secondary rotates fast with ~1.2 d rotation period, and is seen at ~20° inclination. Our spectropolarimetric measurements revealed that the secondary component has a magnetic field with at least a few hundred Gauss strength, while no magnetic field was detected in the primary. The detailed analysis and results of this study will be published elsewhere.

Sódor, Á.; De Cat, P.; Wright, D. J.; Neiner, C.; Briquet, M.; Dukes, R. J.; Fekel, F. C.; Henry, G. W.; Williamson, M. H.; Muterspaugh, M. W.; Brunsden, E.; Pollard, K. R.; Cottrell, P. L.; Maisonneuve, F.; Kilmartin, P. M.; Matthews, J. M.; Kallinger, T.; Beck, P. G.; Kambe, E.; Engelbrecht, C. A.; Czanik, R. J.; Yang, S.; Hashimoto, O.; Honda, S.; Fu, J.-N.; Castanheira, B.; Lehmann, H.; Behara, N.; Van Winckel, H.; Scaringi, S.; Menu, J.; Lobel, A.; Lampens, P.; Mathias, P.

2014-02-01

231

Spectroscopical Analysis of Mechano-chemically Activated Surfaces  

E-print Network

methods. The dynamics and kinetics of mechano-chemically activated surfaces will be studied using x-ray spectroscopy methods. Mechano-chemical interactions can be quantified through the study of electron energies. X-ray spectroscopy is a useful method...

Cooper, Rodrigo

2012-10-19

232

In-beam spectroscopic studies of the 44S nucleus  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

233

Mössbauer spectroscopic study of meteorites recovered on Antarctica  

NASA Astrophysics Data System (ADS)

The chemical states of iron in sixteen Antarctic meteorites belonging to H-group chondrites were studied by means of Mössbauer spectroscopy. An Fe-Ni alloy, troilite, paramagnetic Fe(III), and two kinds of paramagnetic Fe(II) were observed in each meteorite. The Mössbauer parameters indicated that the Fe(II) components can be assigned to olivine and some pyroxenes. The relative area intensities of Fe(III) in the chondrites correlated positively with iodine content, which was determined by radiochemical neutron activation analysis, and those of two Fe(II)-species correlated negatively with the content. On the basis of the data on the halogen and the Mössbauer spectrocopy, the terrestrial contamination on Antarctic meteorites is discussed.

Endo, Kazutoyo; Hirunuma, Rieko; Shinonaga, Taeko; Ebihara, Mitsuru; Nakahara, Hiromichi

1994-12-01

234

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

PubMed

We have studied the carbonate mineral kamphaugite-(Y)(CaY(CO3)2(OH)·H2O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088cm(-1) provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the ?4 region offers further support for the non-equivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed. PMID:25710116

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

2015-05-15

235

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

236

The ARAUCARIA project: Grid-Based Quantitative Spectroscopic Study of Massive Blue Stars in NGC55  

E-print Network

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. 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 NGC55 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. Based on the characteristics of the stellar atmosphere/line formation code FASTWIND, we designed and cr...

Castro, N; Herrero, A; Garcia, M; Simón-Díaz, S; Bresolin, F; Pietrzynski, G; Kudritzki, R -P; Gieren, W

2012-01-01

237

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

238

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

SciTech Connect

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, E-mail: nakamu@tagen.tohoku.ac.jp; Sato, Shunichi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Herbani, Yuliati [Research Center for Physics, Indonesian Institute of Science, Kawasan Puspiptek Serpong Gedung 440, JI. Raya Puspiptek, Serpong, Tangerang Banten 15314 (Indonesia); Ursescu, Daniel; Banici, Romeo; Dabu, Razvan Victor [National Institute for Laser, Plasma and Radiation Physics (NILPRP), Laser Department, Atomistilor street 409, P. O. Box MG-36, 077125 Bucharest (Romania)

2013-08-15

239

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

240

[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

241

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

PubMed

Fungi are important organisms in ecosystems, in industrial and pharmaceutical production and are valuable food sources as well. Classical identification is often time-consuming and specialistic. In this study, Raman spectroscopy is applied to the analysis of fungal spores of Lactarius, an economically and ecologically important genus of Basidiomycota. Raman spectra of spores of Lactarius controversus Pers.: Fr., Lactarius lacunarum (Romagn.) ex Hora, Lactarius quieticolor Romagn. and Lactarius quietus (Fr.: Fr.) Fr. are reported for the first time. The spectra of these species show large similarity. These spectra are studied and compared with the Raman spectra of reference substances known to occur in macrofungi, including saccharides, lipids and some minor compounds that may serve as specific biomarkers (adenine, ergosterol and glycine). Most Raman bands could be attributed to specific components. In agreement with the biological role of fungal spores, high amounts of lipids were observed, the main fatty acid being oleate. In addition to different types of lipids and phospholipids, the polysaccharides chitin and amylopectin could be detected as well. The presence of trehalose is not equivocally shown, due to overlapping bands. Raman band positions are reported for the observed bands of the different species and reference products. PMID:16165029

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

2005-10-01

242

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

243

Spectroscopic analysis of AgI-DNA complex.  

PubMed

It has recently been reported that C-C mismatches were able to recognize Ag(I) specifically, and form Ag(I)-mediated cytosine-cytosine base pairs (C-Ag(I)-C pair). In this study, we explored DNA sequences, which are appropriate for structural studies of this new type of metal-mediated base pairs. For this experiments, we synthesized four kinds of DNA duplexes including a single C-C mismatch. By using UV spectra, we performed titration experiments of DNA duplexes with AgNO(3). Within the sequences we tested, it was found that the DNA duplex: 5'-CGCGCGTCC-3' x 5'-GGACCCGCG-3' showed 1:1 complexation of this DNA duplex and Ag(I). In addition, a DNA duplex: 5'-TAAATCTAATA-3' x 5'-TATTACATTTA-3' also exhibited a similar character. Therefore, these two DNA duplexes are interesting candidates for structural analyses. PMID:17150886

Oda, Shuji; Komuro, Tomoyuki; Kondo, Yoshinori; Ono, Akira; Tanaka, Yoshiyuki

2006-01-01

244

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

245

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

246

A SPECTROSCOPIC SURVEY AND ANALYSIS OF BRIGHT, HYDROGEN-RICH WHITE DWARFS  

SciTech Connect

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

Gianninas, A.; Bergeron, P. [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada); Ruiz, M. T., E-mail: gianninas@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca, E-mail: mtruiz@das.uchile.cl [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile)

2011-12-20

247

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

248

Carbohydrate binding and unfolding of Spatholobus parviflorus lectin: fluorescence and circular dichroism spectroscopic study.  

PubMed

Biophysical and carbohydrate binding studies have been carried out on a lectin of Spatholobus parviflorus (SPL) seeds isolated by affinity chromatography on cross-linked guar gum. It agglutinated erythrocytes of all ABO blood groups. SDS-PAGE, both in reducing and non-reducing conditions, showed two bands with MW of 29 and 31 kDa. MALDI TOF analysis revealed two peaks at 60 and 120 kDa, indicating that SPL is a hetero-dimeric tetramer. Temperature and pH stability studies revealed that SPL is a thermostable protein and its lectin activity is unaffected in the temperature range of 0-70 °C. Its activity was maximal in the pH range of 7-8. Unfolding studies with different denaturants like urea and guanidine hydrochloride indicated its globular nature and the presence of tryptophan in the highly hydrophobic area, which could be correlated to the results of fluorescence spectroscopic studies. The effect of carbohydrate binding on the lectin, shown by circular dichroism spectra, indicated the changes in its secondary and tertiary structures. SPL exerted anti-fungal activity against Aspergillus sp. PMID:23817785

K, Geethanandan; Joseph, Abhilash; C, Sadasivan; Haridas, M

2013-09-01

249

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

250

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

251

A theoretical and spectroscopic study of conformational structures of piroxicam  

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

252

HPLC assisted Raman spectroscopic studies on bladder cancer  

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

253

Spectroscopic analysis of global tide gauge sea level data  

NASA Technical Reports Server (NTRS)

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

Trupin, A.; Wahr, J.

1990-01-01

254

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

255

[Infrared spectroscopic analysis of Guilin watermelon frost products].  

PubMed

The objective of the present study is to analyze different products of Guilin watermelon frost by Fourier transform infrared spectroscopy (FTIR), second derivative infrared spectroscopy and two-dimensional correlation spectroscopy (2D-IR) under thermal perturbation. The structural information of the samples indicates that samples from the same factory but of different brands had some dissimilarities in the IR spectra, and the type and content of accessories of them were different compared with conventional IR spectra of samples, peaks at 638 and 616 cm(-1) all arise from anhydrous sodium sulfate in watermelon frost spray and watermelon frost capsule; the characteristic absorption peaks of the sucrose, dextrin or other accessories can be seen clearly in the spectra of watermelon frost throat-clearing buccal tablets, watermelon frost throat tablets and watermelon frost lozenge. And the IR spectra of watermelon frost lozenge is very similar to the IR spectra of sucrose, so it can be easily proved that the content of sucrose in watermelon frost lozenge is high. In the 2D-IR correlation spectra, the samples presented the differences in the position, number and relative intensity of autopeaks and correlation peak clusters. Consequently, the macroscopical fingerprint characters of FTIR, second derivative infrared spectra and 2D-IR spectra can not only provide the information about main chemical constituents in medical materials, but also analyze and identify the type and content of accessories in Guilin watermelon frost. In conclusion, the multi-steps IR macro-fingerprint method is rapid, effective, visual and accurate for pharmaceutical research. PMID:23156761

Huang, Dong-lan; Chen, Xiao-kang; Xu, Yong-qun; Sun, Su-qin; Zhou, Qun; Lu, Wen-guan

2012-08-01

256

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

257

Air-Liquid Interfaces of Aqueous Solutions Containing Ammonium and Sulfate: Spectroscopic and Molecular Dynamics Studies  

E-print Network

Air-Liquid Interfaces of Aqueous Solutions Containing Ammonium and Sulfate: Spectroscopic ammonium (NH4 + ) and sulfate (SO4 2- ) ions were carried out using molecular dynamics simulations used to study the effect of ammonium and sulfate ions on the bulk structure of water, whereas surface

258

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

Microsoft Academic Search

Molecular spectroscopy in the millimeter- and submillimeter-wave regions is an important tool in molecular physics. Information on molecular motions and interactions is obtained from spectroscopic studies of energy levels and collisions. This information and the data from which it is derived are essential in remote sensing of the atmosphere and the interstellar medium. Remote sensing at submillimeter wavelengths is now

John Christoffersen Pearson

1995-01-01

259

Interaction of Indolicidin with Model Lipid Bilayers: FTIR-ATR Spectroscopic Study  

E-print Network

Interaction of Indolicidin with Model Lipid Bilayers: FTIR-ATR Spectroscopic Study Mi Kyung Bahng 30, 1997X An attempt has been made using Fourier transform infrared-attenuated total reflection (FTIR), and dipalmitoylphosphatidylglycerol (DPPG) using the Langmuir-Blodgett (LB) method. From the FTIR-ATR dichroic ratios measured

Park, Jong-Sang

260

X-ray photoelectron spectroscopic studies of valence states produced by ion-sputtering reduction.  

NASA Technical Reports Server (NTRS)

Some preliminary results are presented of X-ray photoelectron spectroscopic measurements of various valence states of Fe and Cu in several compounds using a novel method, ion-sputtering reduction. The potential usefulness of this method for other chemical-physical studies such as multiplet splitting, shakeup satellites, and isoelectronic shifts is emphasized.

Yin, L. I.; Ghose, S.; Adler, I.

1972-01-01

261

Femtosecond spectroscopic study of carminic acid-DNA interactions Radu Comanicia  

E-print Network

reaction from a G base of DNA to the intercalated chromophore, which is associated with the oxidation1 Femtosecond spectroscopic study of carminic acid-DNA interactions Radu Comanicia , Bianca Gabela-sur-Yvette, France Abstract Photo-excited carminic acid and carminic acid-DNA complexes in a buffer solution at pH= 7

Paris-Sud XI, Université de

262

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

Microsoft Academic Search

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

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

2003-01-01

263

Vanadyl(IV) Complexes of Lactobionic Acid: Potentiometric and Spectroscopic Studies  

Microsoft Academic Search

Potentiometric and spectroscopic studies have shown that in the VO(IV)-lactobionic acid system five different species are involved in coordination equilibria. All complexes consist of one metal ion and two ligand molecules. Stability constants for the vanadyl complexes with lactobionic acid are considerably higher than those for uronic acids, although the donor atoms involved in metal ion coordination are exactly the

Henryk Kozlowski; Saad Bouhsina; Patrick Decock; Giovanni Micera; Jolanta Swiatek

1991-01-01

264

FTIR Spectroscopic Study of an Organic/mineral Composite for Bone and Dental Substitute Materials.  

E-print Network

1 FTIR Spectroscopic Study of an Organic/mineral Composite for Bone and Dental Substitute Materials University, ul. Ks. M. Strzody 9, 44-101 Gliwice, Poland. *** David B. Kriser Dental Center, College : 10.1023/A:1018519419539 #12;2 Summary A new injectable biomaterial for bone and dental surgery

Boyer, Edmond

265

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, and chlorite) and two natural zeolites are reported here. Pressed powders of sizeseparated phyllosilicate and natural zeolite samples were heated incrementally from 100°C to 900°C, cooled to room temperature

Glotch, Timothy D.

266

{sup 1}H NMR spectroscopic studies establish that heparanase is a retaining glycosidase  

SciTech Connect

Highlights: •{sup 1}H and {sup 13}C NMR chemical shifts of fondaparinux were fully assigned by 1D and 2D NMR techniques. •Hydrolysis of fondaparinux by heparanase was monitored by {sup 1}H NMR spectroscopy. •Heparanase is established to be a retaining glycosidase. -- Abstract: Heparanase is an endo-?-glucuronidase that cleaves heparan sulfate side chains of proteoglycans in basement membranes and the extracellular matrix (ECM). Heparanase is implicated in several diverse pathological processes associated with ECM degradation such as metastasis, inflammation and angiogenesis and is thus an important target for anti-cancer and anti-inflammatory drug discovery. Heparanase has been classed as belonging to the clan A glycoside hydrolase family 79 based on sequence analysis, secondary structure predictions and mutagenic analysis, and thus it has been inferred that it is a retaining glycosidase. However, there has been no direct experimental evidence to support this conclusion. Herein we describe {sup 1}H NMR spectroscopic studies of the hydrolysis of the pentasaccharide substrate fondaparinux by heparanase, and provide conclusive evidence that heparanase hydrolyses its substrate with retention of configuration and is thus established as a retaining glycosidase. Knowledge of the mechanism of hydrolysis may have implications for future design of inhibitors for this important drug target.

Wilson, Jennifer C., E-mail: jennifer.wilson@griffith.edu.au [Institute for Glycomics, Griffith University Gold Coast Campus, QLD 4222 (Australia); Laloo, Andrew Elohim [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia)] [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia); Singh, Sanjesh [Institute for Glycomics, Griffith University Gold Coast Campus, QLD 4222 (Australia)] [Institute for Glycomics, Griffith University Gold Coast Campus, QLD 4222 (Australia); Ferro, Vito, E-mail: v.ferro@uq.edu.au [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia)] [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia)

2014-01-03

267

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

268

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

PubMed

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. PMID:25554963

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

2015-03-15

269

Raman spectroscopic detection of early stages in DMBA-induced tumor evolution in hamster buccal pouch model: an exploratory study  

NASA Astrophysics Data System (ADS)

Oral cancers are the serious health problem in developing as well as developed world, and more so in India and other south Asian countries. Survival rate of these cancers, despite advances in treatment modalities are one of the poorest which is attributed to lack of reliable screening and early detection methods. The hamster buccal pouch (HBP)carcinogenesis model closely mimics human oral cancers. Optical spectroscopy methods are sensitive enough to detect subtle biochemical changes and thus hold great potential in early detection of cancers. However, efficacy of these techniques in classifying of sequential evolution of tumors has never been tested. Therefore, in this study, we have explored the feasibility of Raman spectroscopic classification of different stages of cancers in hamster model. Strong vibrational modes of lipids (1440, 1654, and 1746 cm-1) are seen in control tissue spectra, whereas strong protein bands are seen in spectra of DMBA treated tissues. These differences were exploited to classify control and treated tissues using Linear Discriminant Analysis (LDA), Principle Component Analysis (PCA)-Limit test, Factorial Discriminant Analysis (FDA), Quadratic Discriminant Analysis (QDA), PLS-DA and non- linear decision tree methods. All these techniques have shown good classification between spectra of different stages of tumor evolution and results were further successfully verified by leave-one-out and single blinded methods. Thus findings of this study, first of its kind,demonstrate the feasibility of Raman spectroscopic detection of early changes in tumor evolution.

Ghanate, Avinash D.; Kumar, G.; Talathi, Sneha; Maru, G. B.; Krishna, C. Murali

2010-12-01

270

Solvated crystalline forms of nevirapine: thermoanalytical and spectroscopic studies.  

PubMed

The study is aimed at exploring the utility of thermoanalytical methods in the solid-state characterization of various crystalline forms of nevirapine. The different forms obtained by recrystallization of nevirapine from various solvents were identified using differential scanning calorimetry and thermogravimetric analysis (TGA). The appearance of desolvation peak accompanied by weight loss in TGA indicated the formation of solvates: hemi-ethanolate (Form I), hemi-acetonitrilate (Form II), hemi-chloroformate (Form III), hemi-THF solvate (Form IV), mixed hemi-ethanolate hemi-hydrate (Form V), and hemi-toluenate (Form VI). The higher desolvation temperatures of all the solvates except toluenate than their respective boiling point indicate tighter binding of solvent. Emphasis has been laid on the determination of heat capacity and heat of solution utilizing microreaction calorimeter to further distinguish the various forms. The enthalpy of solution (?H(sol)), an indirect measure of the lattice energy of a solid, was well correlated with the crystallinity of all the solid forms obtained. The magnitude of ?H(sol) was found to be -14.14 kJ/mol for Form I and -2.83 kJ/mol for Form V in phosphate buffer of pH 2, exhibiting maximum ease of molecular release from the lattice in Form I. The heat capacity for solvation (?C(p)) was found to be positive, providing information about the state of solvent molecules in the host lattice. The solubility and dissolution rate of the forms were also found to be in agreement with their enthalpy of solution. Form (I), being the most exothermic, was found to be the most soluble of all the forms. PMID:20737259

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

2010-09-01

271

Spectroscopic study of the exotic nucleus 25P  

NASA Astrophysics Data System (ADS)

Motivated by the importance of 25P for the two-proton decay of 26S and for searches of the mirror analog of the island of inversion near N =16 , we present the first predictions for the spectroscopy of the exotic isotope 25P obtained in the shell model, a potential model, and a microscopic-cluster model. All models predict 25P to be unbound, with an energy in the range 0.78 -1.03 MeV, which favors previous mass systematics over more recent revisions. We show that 25P possesses a rich low-lying spectrum that should be accessible by experimental studies. All of the predicted states below 7 MeV, except one, are narrow. Many of them are built on the excited-core states of 24Si for which the Coulomb barrier is raised. For decays into the 24Si (g.s.) +p channel we determined the proton widths based on their link to the asymptotic normalization coefficients (ANCs) of their mirror analogs in 25Ne . We determine these ANCs from the analysis of the transfer reaction 24Ne (d,p ) 25Ne . The proton widths for decay into excited-state channels are obtained in model calculations. The only broad state is the intruder 3 /2 -, the mirror analog of which has been recently observed in 25Ne . The 25P (3 /2-) energy is lower than that in 25Ne , suggesting that the island of inversion may persist on the proton-rich side. All excited states of 25P have at least two decay modes and are expected to populate variously the 21,2 + and 4+ states in 24Si , which then decay electromagnetically.

Fernández-Domínguez, B.; Pereira-López, X.; Timofeyuk, N. K.; Descouvemont, P.; Catford, W. N.; Delaunay, F.

2015-02-01

272

Analysis of interaction between tamoxifen and ctDNA in vitro by multi-spectroscopic methods  

Microsoft Academic Search

Multi-spectroscopic methods including resonance light scattering (RLS), ultraviolet spectra (UV), fluorescence spectra, 1H NMR spectroscopy, coupled with thermo-denaturation experiments were firstly used to study the interaction of antitumor drug tamoxifen (TMX) with calf thymus (ctDNA) in acetate buffer solutions (pH 4.55). The interaction of TMX with ctDNA could cause a significant enhancement of RLS intensity, the hyperchromic effect, red shift

Changqun Cai; Xiaoming Chen; Fei Ge

2010-01-01

273

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

DOEpatents

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

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

1997-01-01

274

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

DOEpatents

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

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

1997-03-04

275

Sensitivity analysis for OMOG and EUV photomasks characterized by UV-NIR spectroscopic ellipsometry  

NASA Astrophysics Data System (ADS)

We investigated the potentials, applicability and advantages of spectroscopic ellipsometry (SE) for the characterization of high-end photomasks. The SE measurements were done in the ultraviolet-near infrared (UVNIR) wavelength range from 300 nm to 980 nm, at angle of incidences (AOI) between 10 and 70° and with a microspot size of 45 x 10 ?m2 (AOI=70°). The measured ? and 𝛥 spectra were modeled using the rigorous coupled wave analysis (RCWA) to determine the structural parameters of a periodic array, i.e. the pitch and critical dimension (CD). Two different types of industrial photomasks consisting of line/space structures were evaluated, the reflecting extreme ultraviolet (EUV) and the transmitting opaque MoSi on glass (OMOG) mask. The ? and 𝛥 spectra of both masks show characteristic differences, which were related to the Rayleigh singularities and the missing transmission diffraction in the EUV mask. In the second part of the paper, a simulation based sensitivity analysis of the Fourier coefficients ? and ? is presented, which is used to define the required measurement precision to detect a CD deviation of 1%. This study was done for both mask types to investigate the influence of the stack transmission. It was found that sensitivities to CD variations are comparable for OMOG and EUV masks. For both masks, the highest sensitivities appear close to the Rayleigh singularities and significantly increase at very low AOI. To detect a 1% CD deviation for pitches below 150 nm a measurement precision in the order of 0.01 is required. This measurement precision can be realized with advanced optical hardware. It is concluded that UV-NIR ellipsometry is qualified to characterize photomasks down to the 13 nm technology node in 2020.

Heinrich, A.; Dirnstorfer, I.; Bischoff, J.; Meiner, K.; Richter, U.; Mikolajick, T.

2013-09-01

276

Raman spectroscopic study of synthesized Na-bearing majoritic garnets  

NASA Astrophysics Data System (ADS)

Majoritic garnets in diamond have been considered as the sample from mantle transition zone (e.g. Moore and Gurney, 1985). For non-destructive, in-situ Raman analysis, Gillet et al. (2002) systematically checked chemistry and Raman peak of various majoritic garnets in diamond. They treated majoritic component as number of excess-silica than 3.0 per formula unit. However, in the basaltic system, majorite garnets also have significant amounts of Na. Na substitution is coupled with Si and Ti as follows; Na +Ti = Ca +Al (Ringwood and Lovering, 1970), Na +Si = Ca + Al (Sobolev and Labrentav, 1971; Ringwood and Major, 1971) or Na + Si = Mg + Al (Gasparik, 1989). Each component in garnet is defined as follows; Mj (majorite) component = ((Si-3)-Na)/2), NaSi (Na2MSi5O12 where M= Ca, Mg, Fe2+) component = (Na-T)/2, and NaTi component = Ti/2. Okamoto and Maruyama (2003) conducted UHP experiments in the MORB + H2O system (KNCFMATSH) at 10-19 GPa. They show that 1) Mj and NaTi component are constant and lower than 0.1 at T = 900 \\deg C, and 2) NaSi component increases drastically above 15 GPa although it is neglibly small at P<15 GPa. Raman spectra was newly analyzed using Okamoto and Maruyama (2003)'s run charges. Above 15 GPa, there is a characteristic sharp peak at 910 cm-1 and broad shoulder between 800 and 900 cm-1 as well as broad band near 960 cm-1. Gillet et at (2002) concluded that the former peak at 910cm-1 is the only reliable signature for the majoritic garnet (Si>3). They also implied that the latter two broad peaks are diagnostic feature for Ti rich garnet (> 1wt% of TiO2) as well as peak at 1030 cm-1. However, in all P range (10-19 GPa) of the present study, TiO2 is higher than 1wt%, and there is a peak at 1030 cm-1. Additional Ti-free experiment at 16 GPa, 1200 \\deg C clearly revealed that Na-bearing majoritic garnet has a significant shoulder at 800-900 cm-1. Ref; Gasparik (1989) CMP, 102,389, Gillet et al. (2002) Am.Min., 87, 312, Moore and Gurney (1985)Nature, 318, 553, Okamoto and Maruyama (2003)PEPI, in press, Ringwood and Lovering (1970) EPSL, 7, 371, Ringwood and Major (1971)EPSL, 12, 411, Sobolev and Labrentav (1971)CMP, 31, 1.

Okamoto, K.

2003-12-01

277

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

278

A spectroscopic and photometric study of post main sequence stars in M68  

NASA Astrophysics Data System (ADS)

We present the results of the spectral analysis for 24 post main sequence stars in the metal poor globular cluster M68 ([Fe/H] = -2.23). Our sample includes lower red giant stars, red giant tip stars, red horizontal branch stars and blue horizontal branch stars, therefore spanning 4000 K in Teff, and 3.0 log(g) space. This is the first high-resolution spectroscopic study sampling essentially all post-subgiant evolutionary stages of a very metal poor globular cluster. In the current effort, abundances and atmospheric parameters for all stars in our sample were derived using an internally consistent approach. Special consideration is given to blue horizontal branch stars, as they present a specific set of analytical challenges. Like earlier studies, we also find a small trend of metallicity and evolutionary state, but much less pronounced than before. Abundances of light elements are consistent among the evolutionary stages, while the n-capture elements exhibit traces of r-process enrichment in this cluster. The combination of these results is considered in the discussion of the evolutionary history of M68 and also the difficulties of deriving self-consistent atmospheric parameters over multiple evolutionary stages. Support for this research from the National Science Foundation (grat AST-1211585) is acknowledged with thanks.

Schaeuble, Marc; Preston, George W.; Sneden, Chris; Thompson, Ian; Shectman, Stephen A.; Burley, Gregory S.

2015-01-01

279

Mössbauer spectroscopic studies of iron particulate matter in coal soot  

NASA Astrophysics Data System (ADS)

Recoilless resonant absorption of 14.4 keV gamma-rays from 57Co have been carried out on coal soot deposited on the chimneys of railway engines to identify and characterize the iron particulate matter constituting the air pollutants during coal combustion. The analysis shows the presence of hematite (?-Fe 2O 3), magnetite (Fe 3O 4) and Fe 2+ and Fe 3+ mullite/silicates/glasses.

Harchand, K. S.; Raj, D.

1993-04-01

280

Biogeological Raman spectroscopic studies of Antarctic lacustrine sediments.  

PubMed

Analysis of lacustrine sediments is an accepted method for deciphering the palaeoenvironment of a lake's catchment area, as each strata of the sediment gives information about the rock type it was eroded from and also the state of the lake, i.e. oxic or anoxic. Antarctica has long been accepted as a putative analogue for Mars, so the analysis of Antarctic material may give results that can be compared to sediments on Mars. Raman spectroscopy has been selected as the method of analysis as it does not destroy the sample, can be used in situ and requires very little sample preparation. It is a suitable method for analysing both inorganic and organic matter and a miniature spectrometer is currently being developed for use in the field. The results from the spectrometers can serve as a guide for analysing sediments on Mars. It has been shown that Raman spectroscopy can detect and differentiate between oxic and anoxic sediments. Both 1064 and 785 nm wavelengths are suitable for laser excitation of organic and inorganic matter. PMID:15876550

Moody, C D; Jorge Villar, S E; Edwards, H G M; Hodgson, D A; Doran, P T; Bishop, J L

2005-08-01

281

Spectroscopic study of early-type multiple stellar systems. II. New binary subsystems  

NASA Astrophysics Data System (ADS)

Context. This work is part of a long-term spectroscopic study of a sample of 30 multiple stars with early-type components. In this second paper we present the results for six multiple systems in which new stellar components have been detected. Aims: The main aim is to increase the knowledge of stellar properties and dynamical structure of early-type multiple stellar systems. Methods: Using spectroscopic observations taken over a time baseline of more than five years we measured radial velocities by cross-correlations and spectrally separated the double-lined systems. In addition to the discovery of objects with double-lined spectra, the existence of new spectroscopic subsystems were inferred from the radial velocity variations of single-lined components and through the variation of the barycentric velocity of double-lined subsystems. Orbital elements were calculated when possible. Results: Seven new stellar components and two members that we expect to confirm with new observations have been discovered in the six studied multiples. We present orbital parameters for two double-lined binaries and preliminary orbits for three single-lined spectroscopic binaries. Five of the six analysed systems are quadruples, while the remaining has five components distributed on four hierarchical levels. These multiplicity orders are in fact lower limits, since these systems lack high-resolution visual observations and additional hierarchical levels might exist in that separation range. Conclusions: The six analysed systems have a higher degree of multiplicity and a more complex hierarchical structure than previously known, which suggests that high-order multiple systems are significantly more frequent than currently estimated. The long-term spectroscopic monitoring of multiple systems has shown to be useful for the detection of companions in intermediate hierarchical levels.

Veramendi, M. E.; González, J. F.

2014-07-01

282

Spectroscopic Ellipsometry Studies of CdS:O Layers for Solar Cells  

NASA Astrophysics Data System (ADS)

This work reports the results of spectroscopic ellipsometry study of CdS thin films, deposited on glass substrates in the presence of oxygen at room temperature by rf sputtering. The data acquisition, together with the subsequent linear regression analysis to restore dielectric function has been performed over the photon energy range 1.5-5.0 eV. The obtained oxygen-free CdS films and reference bulk CdS have been found to be very much the same regarding their dielectric function spectra. On the other hand, blue-shift of the main structures in dielectric function has been observed for CdS:O films deposited at 5% value of O/Ar ratio. In spite of the broadening taking place on a par with the shift, the last turns out to be so large that provides transparency of CdS:O thin films in a spectral range above the energy gap of CdS. The obtained results allow to considering CdS:O as an improved window-layer material for solar cell application.

Shim, Yong-Gu; Sakamoto, Junichi; Suzuki, Akinori; Khalilova, Khuraman; Wakita, Kazuki; Mamedov, Nazim; Bayramov, Ayaz; Huseynov, Emil; Hasanov, Ilham

2011-05-01

283

Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands.  

PubMed

Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular O-H?N interactions in salicylaldehyde derivatives between the O-H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory. PMID:25255482

Ferraresi-Curotto, Verónica; Echeverría, Gustavo A; Piro, Oscar E; Pis-Diez, Reinaldo; González-Baró, Ana C

2015-02-25

284

Solvatochromism of 9,10-phenanthrenequinone: An electronic and resonance Raman spectroscopic study  

NASA Astrophysics Data System (ADS)

Solvent effects play a vital role in various chemical, physical, and biological processes. To gain a fundamental understanding of the solute-solvent interactions and their implications on the energy level re-ordering and structure, UV-VIS absorption, resonance Raman spectroscopic, and density functional theory calculation studies on 9,10-phenanthrenequinone (PQ) in different solvents of diverse solvent polarity has been carried out. The solvatochromic analysis of the absorption spectra of PQ in protic dipolar solvents suggests that the longest (1n-?1*; S1 state) and the shorter (1?-?1*; S2 state) wavelength band undergoes a hypsochromic and bathochromic shift due to intermolecular hydrogen bond weakening and strengthening, respectively. It also indicates that hydrogen bonding plays a major role in the differential solvation of the S2 state relative to the ground state. Raman excitation profiles of PQ (400-1800 cm-1) in various solvents followed their corresponding absorption spectra therefore the enhancements on resonant excitation are from single-state rather than mixed states. The hyperchromism of the longer wavelength band is attributed to intensity borrowing from the nearby allowed electronic transition through vibronic coupling. Computational calculation with C2? symmetry constraint on the S2 state resulted in an imaginary frequency along the low-frequency out-of-plane torsional modes involving the C=O site and therefore, we hypothesize that this mode could be involved in the vibronic coupling.

Ravi Kumar, Venkatraman; Rajkumar, Nagappan; Umapathy, Siva

2015-01-01

285

Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands  

NASA Astrophysics Data System (ADS)

Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular Osbnd H⋯N interactions in salicylaldehyde derivatives between the Osbnd H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory.

Ferraresi-Curotto, Verónica; Echeverría, Gustavo A.; Piro, Oscar E.; Pis-Diez, Reinaldo; González-Baró, Ana C.

2015-02-01

286

Hunting the Parent of the Orphan Stream II: The First High-Resolution Spectroscopic Study  

E-print Network

We present the first high-resolution spectroscopic study on the Orphan Stream for five stream candidates, observed with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the Magellan Clay telescope. The targets were selected from the low-resolution catalog of Casey et al. (2013a): 3 high-probability members, 1 medium and 1 low-probability stream candidate were observed. Our analysis indicates the low and medium-probability target are metal-rich field stars. The remaining three high-probability targets range ~1 dex in metallicity, and are chemically distinct compared to the other 2 targets and all standard stars: low [alpha/Fe] abundances 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 an...

Casey, Andrew; Da Costa, Gary; Frebel, Anna; Maunder, Elizabeth

2013-01-01

287

Spectroscopic investigations, molecular interactions, and molecular docking studies on the potential inhibitor "thiophene-2-carboxylicacid".  

PubMed

Thiophene derivatives have been focused in the past decades due to their remarkable biological and pharmacological activities. In connection with that the conformational stability, spectroscopic characterization, molecular (inter- and intra-) interactions, and molecular docking studies on thiophene-2-carboxylicacid have been performed in this work by experimental FT-IR and theoretical quantum chemical computations. Experimentally recorded FT-IR spectrum in the region 4000-400cm(-1) has been compared with the scaled theoretical spectrum and the spectral peaks have been assigned on the basis of potential energy distribution results obtained from MOLVIB program package. The conformational stability of monomer and dimer conformers has been examined. The presence of inter- and intramolecular interactions in the monomer and dimer conformers have been explained by natural bond orbital analysis. The UV-Vis spectra of the sample in different solvents have been simulated and solvent effects were predicted by polarisable continuum model with TD-DFT/B3LYP/6-31+G(d,p) method. To test the biological activity of the sample, molecular docking (ligand-protein) simulations have been performed using SWISSDOCK web server. The full fitness (FF) score and binding affinity values revealed that thiophene-2-carboxylicacid can act as potential inhibitor against inflammation. PMID:25677530

Karthick, T; Balachandran, V; Perumal, S

2015-04-15

288

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

289

Spectroscopic Binary Star Studies with the Palomar Testbed Interferometer II  

E-print Network

for which we will present new orbit mod- els are: 12 Boo (HD 123999), 75 Cnc (HD 78418), 47 And (HD 8374.4 1.6 27.1 #6; 0.4 27.3 #6; 0.8 BY Dra K6 V 4.4 24 65.8 #6; 5.4 60.9 #6; 0.9 75 Cnc G5 IV 5.9 4.6 31 completed our analysis or have solid provisional solutions: 12 Boo (HD 123999), 75 Cnc (HD 78418), 47

290

Metal distribution and spectroscopic analysis after soil washing with chelating agents and humic substances.  

PubMed

Biodegradable chelating agents ([S,S]-ethylenediamine-N,N-disuccinic acid (EDDS) and glutamic-N,N-diacetic acid (GLDA)) and natural humic substances (lignite-derived, standard, and commercially available humic acids) are potentially useful for enhancing soil remediation of timber treatment sites. This study integrated macroscopic and spectroscopic analyses to assess their influence on the distribution and chemical speciation of the remaining metals as well as their interaction with the soil surface after 48-h washing of a field-contaminated soil. The results demonstrated that EDDS and GLDA were an appealing alternative to non-biodegradable ethylenediamine-tetraacetic acid, but the three humic substances were less effective. As shown by sequential extractions, Cu was primarily extracted from the carbonate fraction while Cr and As extraction resulted from (co-)dissolution of the oxide fraction. As a result, the relative proportion of strongly bound organic matter and residual fractions increased by 7-16 %. However, it was noteworthy that the exchangeable fraction also increased by 5-11 %, signifying that a portion of the remaining metals was destabilized by chelating agents and transformed to be more labile in the treated soil. The X-ray photoelectron spectroscopy spectra confirmed the substantial removal of readily accessible Cu from the soil surface, but Cr maintained its original chemical forms of trivalent chromium oxides and iron-chromium coprecipitates, whereas As remained as arsenic trioxide/pentoxide and copper arsenate precipitates. On the other hand, the absence of characteristic peaks of adsorbed carboxylate groups in the Fourier-transform infrared (FTIR) spectra inferred that the extent of adsorption of chelating agents and humic substances on the bulk soil was insufficient to be characterized by FTIR analysis. These results suggested that attention should be paid to the exchangeable fraction of Cu and oxides/coprecipitates of As prior to possible on-site reuse of the treated soil. PMID:24297462

Tsang, Daniel C W; Hartley, Neil R

2014-03-01

291

Resonance Raman spectroscopic study of fused multiporphyrin linear arrays  

NASA Astrophysics Data System (ADS)

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

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

2003-09-01

292

Laser-induced breakdown spectroscopic study of ammonium nitrate plasma  

SciTech Connect

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

Hanif, M., E-mail: drhanif-mcs@nust.edu.pk [MCS, National University of Sciences and Technology (Pakistan); Salik, M. [Beijing Jiaotong University, Institute of Optoelectronics (China); Baig, M. A. [Quaid-E-Azam University Campus, National Center for Physics (Pakistan)

2013-12-15

293

Spectroscopic and dynamical studies of highly energized small polyatomic molecules  

SciTech Connect

The formyl radical and the acetylene molecule were chosen for these studies. The visible and fluorescence spectra of the formyl radical were recorded, and the spectral results are used as a basis to explain the electronic structure. Optical-optical double resonance studies of acetylene were recorded, and the spectral results are interpreted. The results of Zeeman and Stark anticrossing and quantum beat studies of acetylene are reported, and they provide an unusually detailed view of both Intersystem Crossing and Internal Conversion in small polyatomic molecules. 22 references are cited as resulting from Department of Energy sponsorship of this project.

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

1990-01-01

294

SPECTROSCOPIC STUDY OF SORPTION OF NITROGEN HETEROCYCLIC COMPOUNDS ON PHYLLOSILICATES  

EPA Science Inventory

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

295

SPECTROSCOPIC STUDIES OF MATERIALS FOR ELECTROCHEMICAL ENERGY STORAGE  

SciTech Connect

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

Greenbaum, Steven G.

2014-03-01

296

Spectroscopic studies of a multiphasic polymer-ceramic mixture material.  

PubMed

We report the results obtained by infrared (IR) and X-ray photoelectron spectroscopy (XPS) on the multiphasic composite material formed by the mixture of biphasic calcium phosphate (BCP) and hydroxypropylmethylcellulose (HPMC). This synthetic material, intended for bone substitution, is injectable and allows percutaneous surgery. Core level spectra of carbon, oxygen, calcium, and phosphorus were recorded on separate components before mixing and then compared to those obtained in the final product. Analysis of the spectra shows that formation of calcium carbonate has occurred upon mixing the components in agreement with IR results. An attempt to explain the formation mechanism of the composite is given involving the nature of the constituents on one hand and the possible reactions between the different components on the other. PMID:8957710

Nguyen, T P; Dupraz, A

1996-01-01

297

Synthesis and spectroscopical study of rhodanine derivative using DFT approaches.  

PubMed

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of (E)-5-benzylidene-2-thioxothiazolidine-4-one (E5BTTO) have been investigated experimentally and theoretically based on Density Functional Theory (DFT) approach. The FT-Raman and FT-IR spectra of E5BTTO were recorded in solid phase. Theoretical calculations were performed at the DFT level using the Gaussian 03 program. The experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumber by their Total Energy Distribution (TED). The results of the calculation were applied to simulate infrared and raman spectra of the title compound which showed good agreement with the observed spectra. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. Stability arising from hyperconjugative interactions leading to its NLO activity and charge delocalization were analyzed using Natural Bond Orbital (NBO) analysis. PMID:25819314

Anbarasan, R; Dhandapani, A; Manivarman, S; Subashchandrabose, S; Saleem, H

2015-07-01

298

Spectroscopic studies of Tl containing high frequency electrodeless lamps  

NASA Astrophysics Data System (ADS)

In this work we estimate gas temperature from OH rotational spectrum at 306.4 nm and C2 Swan band at 516.5 nm in thallium containing lamps during two working regimes: stable generation and self-modulation regime. The usage of both molecules allowed us to estimate gas temperature in different zones of the discharge. The measurement results show that the central part of discharge has temperature higher for about 400 K than in vicinity of lamp inner walls. The measurement results of self-modulation regime showed that rotational temperature variations are similar to that of atomic and molecular spectral line intensities with period being around 1 minute. More detailed analysis of temporal behavior of spectral lines gives us information about collisional processes in the plasma.

Zinge, M.; Gavare, Z.; Gosko, E.

2014-10-01

299

Bi-anisotropy of optical metamagnetics studied with spectroscopic ellipsometry  

E-print Network

is a periodic array of pairs of silver strips 35x100nm separated by an alumina spacer of 40 nm in thickness, WPAFB, OH 45433 vdrachev@ecn.purdue.edu Abstract: Sub-wavelength gratings of paired Ag strips for metamaterials based on split ring resonators. We study bi-anisotropic properties of metamagnetics based

Shalaev, Vladimir M.

300

Photoemission Spectroscopic Study of Cesium Telluride Thin Film Photocathode  

SciTech Connect

The photoemission spectroscopy using synchrotron radiation has been carried out to study the high quantum efficiency and long working lifetime of cesium telluride (Cs{sub x}Te{sub y}) thin film photocathode. The electron affinity derived from the observed energy-distribution curves provides an important hint for long persistency of the photocathode.

Sugiyama, Harue; Ogawa, Koji; Azuma, Junpei; Takahashi, Kazutoshi; Kamada, Masao [Synchrotron Light Application Center, Saga University, 1 Honjo, Saga 840-8502 (Japan)

2009-08-04

301

LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY  

EPA Science Inventory

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

302

Structural and spectroscopic study of adsorption of naphthalene on silver  

NASA Astrophysics Data System (ADS)

Adsorption characteristics of naphthalene on silver are investigated using methods based on Density Functional Theory (DFT) and Surface Enhanced Raman Spectroscopy (SERS). Variations in bond angles and dihedral angles of the optimized geometry of naphthalene after adsorption on silver indicate distorted hexagonal structure of the ring nearer to Ag atoms and deviations in co-planarity of carbon atoms. Theoretical computations establish binding interactions through ? electrons as natural bond orbital analysis confirms intramolecular charge transfers originating from the orbital overlap between ?(Csbnd C) to ??(Csbnd C) and ?(Csbnd C) to ??(Agsbnd Ag) orbitals. Higher polarization values resulting from charge transfers on adsorption, indicated by DFT calculations, account for Raman enhancement of selective vibrational modes and band shifts. Silver nanoparticles (Ag NPs) were prepared using solution combustion method and were characterized by X-ray diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM). Surface plasmon resonance peak observed around 412 nm in the optical absorption spectrum of Ag NPs after adsorption of naphthalene is in good agreement with the theoretically simulated UV spectra derived using Time-Dependent Density Functional Theory (TDDFT) calculations. Theoretical and experimental SERS are correlating well, strongly confirming the process of adsorption, the tilted orientation of naphthalene on silver surface and the adsorption mechanism reported. Localization of electron density resulting from redistribution of electrostatic potential after adsorption on silver together with the reduction in bandgap of naphthalene suggests its utility in the design of electro active organic molecular devices.

Rekha, T. N.; Umadevi, M.; Rajkumar, Beulah J. M.

2015-01-01

303

Raman spectroscopic study of globulin from Phaseolus angularis (red bean)  

Microsoft Academic Search

Fourier-transform Raman spectroscopy was used to study the conformation of red bean globulin (RBG) in various buffered environments and on heat treatment. The Raman spectrum of 20% (w\\/v) freeze-dried RBG in 0.01 M phosphate buffer at pH 7.4 suggests that its secondary structure composition is dominated by ?-sheets and random coils. Extreme pH values caused the amide I and amide

Guangtao Meng; Ching-Yung Ma; David Lee Phillips

2003-01-01

304

Interfacial spectroscopic studies of UV cured urethane acrylate coatings  

Microsoft Academic Search

Interfacial structural changes of UV cured urethane acrylate coating films were investigated using ATR FTIR spectroscopy. These studies show that at the film–air (F–A) interface, when photo-initiator levels do not exceed 0.1% w\\/w, the band area ratio of H-bonding to non-H-bonding carbonyl stretching vibrations is proportional to UV energy density. However, when the initiator level is increased to 5% w\\/w,

Kenichi Yukiyasu; Marek W. Urban

1999-01-01

305

Synthesis and spectroscopic studies of polyorganophosphazenes containing binaphthalene groups  

NASA Astrophysics Data System (ADS)

Introduction of binaphthalene groups in a polymer structure (saturated and unsaturated polyesters, polyimides, polyoxazolydones and other types) increases its thermal stability in comparison with that of the respective polymers containing phenylene and biphenylene groups. A similar effect is observed in condensation polyphosphazenes obtained from monospirobinaphthalenodioxytetrachlorophosphazenes and diphenols which retain the cyclophosphazene structure. It seemed useful to study the possibility of introducing binaphthalene groups to a poly(dichloro)phosphazene structure.

Su?kowski, W.; Su?kowska, A.; Kireev, V.

1997-06-01

306

Spectroscopic and computational study of a new isomer of salinomycin  

NASA Astrophysics Data System (ADS)

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

Pankiewicz, Rados?aw

2013-09-01

307

Photoelectron spectroscopic study of the bonding in borane adducts  

Microsoft Academic Search

The bonding in the adducts BHâ.NHâ, BHâ.N(CHâ)â, BHâ.CO, BHâ.CNCHâ, BHâ.PFâ, and BHâ.P(CHâ)â are studied by using a combination of valence ionization potentials and core binding energies. The data indicate that ..pi.. back-bonding is significant only in BHâ.CO and BHâ.PFâ. The stabilization of the Lewis base lone pair upon coordination to BHâ is correlated with the proton affinity of the Lewis

David B. Beach; William L. Jolly

1985-01-01

308

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

309

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

SciTech Connect

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Picosecond pulse radiolysis studies at BNL's Laser-Electron Accelerator Facility (LEAF) [1] are used to identify reactive species in ionic liquids and measure their solvation and reaction rates. IL solvation and rotational dynamics are measured by TCSPC in the laboratory of E. W. Castner at Rutgers Univ. Investigations of radical species in irradiated ILs are carried out at ANL by I. Shkrob and S. Chemerisov using EPR spectroscopy.

WISHART,J.F.

2007-11-30

310

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

311

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

312

X-ray spectroscopic studies of microbial transformations of uranium  

SciTech Connect

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

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

1995-10-01

313

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

NASA Astrophysics Data System (ADS)

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

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

1999-10-01

314

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

315

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

316

Interaction studies of Epirubicin with DNA using spectroscopic techniques  

NASA Astrophysics Data System (ADS)

Epirubicin (EPR) is an anticancer chemotherapeutic drug which exerts its cytotoxic effect by inhibiting DNA synthesis and DNA replication. We report the structural and conformational effect of EPR binding on DNA duplex under physiological conditions. Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-visible) spectroscopy and circular dichroism (CD) spectroscopy were used to determine the binding mode and binding constant of EPR with DNA. The effect of EPR-DNA complexation on stability and secondary structure of DNA was studied. FTIR measurements showed that EPR-DNA interaction occurs through guanine and cytosine bases. External binding of EPR with DNA was observed through phosphate backbone. UV-visible measurements revealed the intercalative mode of binding of EPR with DNA. The binding constant was estimated to be K = 3.4 × 10 4 which is indicative of moderate binding between EPR and DNA helix. FTIR and CD studies suggested partial transition from B-conformation of DNA to A-conformation of DNA after EPR binding to DNA duplex.

Charak, Sonika; Jangir, Deepak K.; Tyagi, Gunjan; Mehrotra, Ranjana

2011-08-01

317

Vibrational spectroscopic studies of adsorbates on bimetallic surfaces. Doctoral thesis  

SciTech Connect

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

Kuhn, W.K.

1992-12-01

318

A Spectroscopic and Mineralogical Study of Multiple Asteroid Systems  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

319

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

PubMed

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

Jebaraj, Adriel Jebin Jacob; Scherson, Daniel A

2013-05-21

320

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

321

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  

NASA Astrophysics Data System (ADS)

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. 1H and 13C 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.

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

2015-01-01

322

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

323

Spectroscopic structural studies of salicylic acid, salicylamide and aspirin  

NASA Astrophysics Data System (ADS)

The electronic absorption spectra of the salicylic acid and the salicylamide molecules have been studied using SCF—CL calculations. The singlet and the triplet electronic transition energies have been calculated. The state functions of eight excited states for these molecules have been calculated in addition to the oscillator strengths, charge densities, ionization potentials and electron affinities. Our calculations lead to the presence of salicylic acid and salicylamide in the ?-forms in which the carboxylic hydroxyl group or the amino group is directed toward the enolic hydroxyl group. The salicylic acid and the salicylamide molecules have the Cs point group symmetry, but the aspirin molecule has the C1 point group symmetry, in which the acetyl group does not lie in the plane of the salicylic acid molecule.

El-Shahawy, Anwar S.

324

Raman spectroscopic study of plasma-treated salmon DNA  

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

325

Enhanced Raman spectroscopic study of rotational isomers on metal surfaces  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

326

Fourier transform infrared and electron paramagnetic resonance spectroscopic studies of thylakoid membranes  

Microsoft Academic Search

Changes in both structure and dynamics of thylakoid membranes exposed to heat stress during greening of etiolated barley seedlings were studied using complementary spectroscopic techniques. FTIR spectra of thylakoid membranes were analyzed in the Amide I and the symmetric CH2 stretching vibration regions providing data on protein secondary structures and lipid acyl chain conformations, respectively. The partitioning of 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO)

Zoltán Kóta; Balázs Szalontai; Magdolna Droppa; Gábor Horváth; Tibor Páli

1999-01-01

327

Spectroscopic Studies on Impurity Transport of Core and Edge Plasmas in LHD  

Microsoft Academic Search

Spectroscopic diagnostics have been extensively developed for studies of impurity and neutral particle transports at core and edge plasmas in LHD. Diagnostics of core plasmas are similar to a tokamak case, i.e., Zeff from visible bremsstrahlung, K-x-ray measurements from x-ray spectroscopy using Si(Li) detectors and a compact crystal spectrometer, and high-Z impurity diagnostics from VUV spectroscopy using a flat-field EUV

Morita Shigeru; Goto Motoshi; Muto Sadatsugu; Katai Ryuji; Yamazaki Hisamichi; Nozato Hideaki; Iwamae Atsushi; Atake Makoto; Fujimoto Takashi; Sakaue Atsushi; Nishimura Hiroaki; Sakurai Ikuya; Matsumoto Chiho; Furuzawa Akihiro; Tawara Yuzuru; Aramaki Mitsutoshi; Okumura Yuji; Sasaki Koichi; Xianzu Gong; Jiangang Li; Baonian Wan; Zhengying Cui

2006-01-01

328

A vibrational spectroscopic study of the silicate mineral ardennite-(As).  

PubMed

We have used a combination of scanning electron microscopy with EDX and vibrational spectroscopy to study the mineral ardennite-(As). The mineral ardennite-(As) of accepted formula Mn4(2+)(Al,Mg)6(Si3O10)(SiO4)2(AsO4,VO4)(OH)6 is a silicate mineral which may contain arsenate and/or vanadates anions. Because of the oxyanions present, the mineral lends itself to analysis by Raman and infrared spectroscopy. Qualitative chemical analysis shows a homogeneous phase, composed by Si, Mn, Al and As. Ca and V were also observed in partial substitution for Mn and As. Raman bands at 1197, 1225, 1287 and 1394 cm(-1) are assigned to SiO stretching vibrations. The strong Raman bands at 779 and 877 cm(-1) are assigned to the AsO4(3-) antisymmetric and symmetric stretching vibrations. The Raman band at 352 cm(-1) is assigned to the ?2 symmetric bending vibration. The series of Raman bands between 414 and 471 cm(-1)are assigned to the ?4 out of plane bending modes of the AsO4(3-) units. Intense Raman bands observed at 301 and 314 cm(-1) are attributed to the MnO stretching and bending vibrations. Raman bands at 3041, 3149, 3211 and 3298 cm(-1) are attributed to the stretching vibrations of OH units. There is vibrational spectroscopic evidence for the presence of water adsorbed on the ardennite-(As) surfaces. PMID:24161862

Frost, Ray L; López, Andrés; Xi, Yunfei; Scholz, Ricardo; Gandini, Antonio Luciano

2014-01-24

329

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

SciTech Connect

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

Hey, J. D. [School of Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000 (South Africa); Brezinsek, S.; Mertens, Ph.; Unterberg, B. [Institut fuer Plasmaphysik, Forschungszentrum Juelich, Association EURATOM-FZJ, Trilateral Euregio Cluster (Germany)

2006-12-01

330

Optical properties of As33S67-xSex bulk glasses studied by spectroscopic ellipsometry  

NASA Astrophysics Data System (ADS)

Variable angle spectroscopic ellipsometry (VASE) was employed to study the optical properties of As33S67-xSex (x =0, 17, 33.5, 50, and 67at.%) bulk glasses in the UV-vis-NIR (near infrared) spectral region for photon energies from 0.54to4.13eV (photon wavelengths from 2300to300nm). For data analysis, we employed Tauc-Lorentz (TL) dispersion model in the entire measured near bandgap spectral region and standard Cauchy dispersion model in the spectral region below the bandgap. With increasing Se content (x) in the bulk glass, we observed a linear decrease in optical bandgap energy Egopt from 2.52±0.02eV for As33S67 to 1.75±0.01eV for As33Se67 and linear increase in refractive index nTL in the NIR spectral region, e.g., at 0.80eV from 2.327 for As33S67 to 2.758 for As33Se67. The amplitude A decreased with increasing Se content. The peak transition energy E0 and broadening C had a maximum value for x =33.5at.% and systematically decreased for higher S or Se content in glasses. Our study showed that TL model is suitable to describe dielectric functions of studied chalcogenide bulk glasses in the broad spectral region. The bulk glasses had a higher refractive index compared to thin films of corresponding composition. The bulk glasses with high S content had higher value of optical bandgap energy than was previously reported for thin films. The optical bandgap energy of glasses with higher Se content was very similar to the thin films.

Orava, J.; Šik, J.; Wágner, T.; Frumar, M.

2008-04-01

331

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.

2012-06-26

332

Spectroscopic studies on the antioxidant activity of ellagic acid  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

333

Spectroscopic studies on the antioxidant activity of ellagic acid.  

PubMed

Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 ?g/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), ?-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTS+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, ?-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties. PMID:24813273

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

2014-09-15

334

Synchronous fluorescence spectroscopic study of solvatochromic curcumin dye  

NASA Astrophysics Data System (ADS)

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

Patra, Digambara; Barakat, Christelle

2011-09-01

335

Reduction of selenite on iron surfaces: Amicro-spectroscopic study  

NASA Astrophysics Data System (ADS)

Under anoxie conditions zero-valent iron can react with water to produce hydrogen gas and magnetite or green rust, a highly reactive mineral phase that can induce reduction processes and thus control the speciation, the solubility, toxicity and the mobility of redox sensitive elements in (nuclear) waste repositories. In this study micro X-ray fluorescence (micro-XRF) and micro X-ray absorption spectroscopy (micro-XAS) were used to investigate the speciation of selenium that immobilized in the presence of Fe(0) and an anoxie synthetic groundwater solution. The selenium immobilization was accompanied by the formation of a green rust corrosion layer. Micro-XRF revealed that a Se-rich layer is present along the iron surfaces that were exposed to the Se(IV) solution. Micro-XAS experiments at the Se K-edge showed that Se(IV) was reduced to elemental Se(0). Thus, the reactivity of zero-valent and green rust should to be considered in assessing the long-term fate of selenium in nuclear waste repositories.

Scheidegger, A. M.; Grolimund, D.; Cui, D.; Devoy, J.; Spahiu, K.; Wersin, P.; Bonhoure, I.; Janousch, M.

2003-03-01

336

Luminescence and spectroscopic studies of halosulfate phosphors: a review.  

PubMed

This review discusses the photoluminescence (PL) characteristics of halosulfate phosphors developed by us. Halosulfate phosphors KCaSO4 Cl:X,Y (X?=?Eu or Ce; Y?=?Dy or Mn) and Na6 (SO4 )2 FCl (doped with Dy, Ce or Eu) were prepared using a solid-state diffusion method. The mechanism of energy transfer from Eu(2+) ?Dy(3+) , Ce(3+) ?Dy(3+) and Ce(3+) ?Mn(2+) has also been studied. Dy(3+) emission in the host at 475 and 570?nm is observed due to (4) F9/2 ?(6) H15/2 and (4) F9/2 ?(6) H13/2 transition, whereas the PL emission spectra of Na6 (SO4 )2 FCl:Ce phosphor shows Ce(3+) emission at 322?nm due to 5d?4f transition of the Ce(3+) ion. The main property of KCaSO4 Cl is its very high sensitivity, particularly when doped by Dy, Mn or Pb activators. This review also discusses the PL characteristics of some new phosphors such as LiMgSO4 F, Na6 Pb4 (SO4 )6 Cl2 , Na21 Mg(SO4 )10 Cl3 and Na15 (SO4 )5 F4 Cl. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25045016

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

2015-03-01

337

A spectroscopic study of the reduction of geometrically restrained viologens.  

PubMed

A small series of N,N'-dimethyl-4,4'-bipyridinium dication derivatives (commonly known as viologens) has been synthesized and fully characterized; a short dialkoxy tether attached at the 3,3'-positions is used to alter the central dihedral angle. These angles were determined by both single-crystal X-ray diffraction and by computational studies made for the dication, radical cation, and neutral species in a solvent reservoir. The dihedral angle derived for the dication controls the first reduction potential, whereas the geometry of the resultant pi-radical cation determines the magnitude of the second reduction potential. The optical absorption spectra recorded for the various species, and especially those of the radical cations, and the EPR spectral parameters of the pi-radical cations also depend on the molecular geometry. In particular, the central dihedral angle influences the spin density distribution around the aromatic nucleus and, by way of comparison to the parent viologen, it has been possible to resolve the angle dependence from the inherent inductive effect of the strap. These results are considered in terms of the degree of electronic communication between the two aromatic rings, as controlled by the length of the tether. PMID:17721887

Benniston, Andrew C; Harriman, Anthony; Li, Peiyi; Rostron, James P; Harrington, Ross W; Clegg, William

2007-01-01

338

Raman spectroscopic study of chemically-doped few layer graphenes  

NASA Astrophysics Data System (ADS)

Graphene, the latest carbon allotrope discovered at 2004, has attracted intensively scientific interest owing to its distinctive properties. Chemical doping is expected to substantially increase the density of free charge carriers by charge transfer and to modify the Fermi level of doped materials. Here, we investigated charge transfer and optical phonon mixing in few layer graphenes in detail by utilizing sulfuric acid as an electron-acceptor dopant. Sulfuric acid molecules are found to be only physically adsorbed on the surface layers of graphenes and no intercalation happens. The top and bottom layers of bilayer graphenes can be intentionally doped differently by concentrated sulfuric acid. The difference of hole doping between the top and bottom layers results in phonon mixing of symmetric and antisymmetric modes in bilayer graphenes. The Raman frequency evolution with the doping level qualitatively agrees with recent ab initio theoretical calculations. Sulfuric acid molecules can be expected as a stable electron-acceptor dopant for graphenes to study the physical properties of few layer graphenes at different doping levels.

Tan, Pingheng; Zhao, Weijie; Zhang, Jun; Liu, Jian

2011-03-01

339

A laser spectroscopic study of Nd-doped Zirconia  

SciTech Connect

High-surface-area rare-earth (RE) modified zirconia powders prepared by solution methods can be used as catalytic support of noble metals and as electrolyte oxygen sensors in automobile exhaust-emission- control systems. Previous neutron-scattering study showed that substituting Zr with trivalent RE ions not only stabilizes the cubic and tetrgonal phases over a wide range of temperatures but also creates oxygen vacancies in the RE-Zr oxide solid solution. This work focuses on Nd fluorescence in Nd{sub 0.1}Zr{sub 0.9}O{sub 1.95} powders under laser excitation of the Nd{sup 3+} ground state to the {sup 4}G{sub 7.2} states. Distinct features were found at 8K in the {sup 4}I{sub 9/2}{r_arrow}{sup 4}G{sub 7/2} excitation and {sup 4}F{sub 3.2}{r_arrow}{sup 4}I{sub 9/2} emission spectra using two sets of incident and emission frequencies, respectively. Results are discussed in terms of site-sensitive local structures surrounding the Nd ions in the two-phased oxide structure.

Loong, C.-K.; Liu, G.K. [Argonne National Lab., IL (United States); Ozawa, M.; Suzuki, S. [Nagoya Inst. of Tech. (Japan)

1996-06-01

340

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

341

Oxidation of pyrite surfaces: a photoelectron spectroscopic study  

NASA Astrophysics Data System (ADS)

Surfaces of pyrite (FeS 2) differently prepared in situ and ex situ have been studied before and after contact to air and air-saturated aqueous solutions of 4?pH?10 by means of photoelectron spectroscopy. Pyrite surfaces fractured or scraped in situ revealed FeS-like species concentrated in the surface region. Preparation (polishing, grinding, powdering) and prolonged oxidation in air mainly resulted in basic iron sulphate and iron oxide/hydroxide. A promoting effect of an increased surface roughness due to the preparation was observed for the formation of iron oxide/hydroxide compared with sulphate in contrast to the natural oxidation process. Oxidation in air also led to sulphur-rich species identified as iron-deficient regions below monolayer coverage. Similar regions were present at ground surfaces exposed to air-saturated solution of pH4 and pH5. In near-neutral to alkaline solution mainly iron hydroxy-oxide is formed the layer thickness of which was estimated in the range of 0.5 nm (pH5) to 1.7 nm (pH10).

Karthe, S.; Szargan, R.; Suoninen, E.

1993-10-01

342

A spectroscopic study of laser ablation plasma from Mo target  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

343

A spectroscopic study of IRAS F10214+4724  

E-print Network

The z=2.286 IRAS galaxy F10214+4724 remains one of the most luminous galaxies in the Universe, despite its gravitational lens magnification. We present optical and near-infrared spectra of F10214+4724, with clear evidence for three distinct components: lines of width ~1000 km/s from a Seyfert-II nucleus; <~200 km/s lines which are likely to be associated with star formation; and a broad ~4000 km/s CIII] 1909ang emission line which is blue-shifted by ~1000 km/s with respect to the Seyfert-II lines. Our study of the Seyfert-II component leads to several new results, including: (i) From the double-peaked structure in the Ly alpha line, and the lack of Ly beta, we argue that the Ly alpha photons have emerged through a neutral column of N_H ~ 2.5 x 10^{25}/m^2, possibly located within the AGN narrow-line region as argued in several high redshift radiogalaxies. (ii) The resonant O VI 1032,1036ang doublet (previously identified as Ly beta) is in an optically thick (1:1) ratio. At face value this implies an an extreme density (n_e ~ 10^{17}/m^3) more typical of broad line region clouds. However, we attribute this instead to the damping wings of Ly beta from the resonant absorption. (iii) A tentative detection of HeII 1086 suggests little extinction in the rest-frame ultraviolet.

Stephen Serjeant; Steve Rawlings; Mark Lacy; Richard G. McMahon; Andy Lawrence; Michael Rowan-Robinson; Matt Mountain

1998-02-16

344

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

345

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

346

Spectroscopic investigation (FT-IR and FT-Raman), vibrational assignments, HOMO-LUMO, NBO, MEP analysis and molecular docking study of 2-(4-hydroxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide.  

PubMed

In this work, the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy of 2-(4-hydroxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide. The computations were performed at DFT levels of theory to get the optimized geometry and vibrational frequencies of the normal modes of the title compound using Gaussian09 software. The complete vibrational assignments of frequencies were made on the basis of potential energy distribution. The calculated HOMO and LUMO energies show the chemical activity of the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The hyperpolarizability values are reported and the first hyperpolarizability of the title compound is 19.61 times that of standard NLO material urea. From the MEP plot, the negative charge covers the nitro group and the positive region is over the hydroxyl group and N-H part of the imidazole ring. The calculated (1)H NMR results are in good agreement with experimental data. Molecular docking study is also reported. PMID:25819320

Benzon, K B; Varghese, Hema Tresa; Panicker, C Yohannan; Pradhan, Kiran; Tiwary, Bipransh Kumar; Nanda, Ashis Kumar; Alsenoy, C Van

2015-07-01

347

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

348

Electrochemical and spectroscopic studies of the interaction between the neuroleptic drug, gabapentin, and DNA.  

PubMed

The interaction between gabapentin (GP), a neuroleptic drug, and calf-thymus DNA was investigated. Cyclic voltammetry and different spectroscopic methods (UV/vis spectrophotometry, spectroflourimetry and circular dichroism) were used to study the process. The oxidation current of GP was considerably decreased in the presence of calf-thymus DNA. The negative shift of the peak potential in cyclic voltammetry suggested an electrostatic interaction, while spectroscopic methods show minor groove binding as the predominant mode. The values of binding constants obtained from UV absorption, spectrofluorimetry and voltammetric measurements were in close agreement. Standard Gibbs free energy change, ?G(0), of the interaction was calculated to be -21.99 kJ mol(-1) which indicated the spontaneity of the binding interaction. A hyperchromic effect in the maximum absorption band of DNA as well as quenching in fluorescence experiments were observed in the presence of GP. PMID:22742920

Jalali, Fahimeh; Dorraji, Parisa S

2012-11-01

349

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

350

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

351

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

352

A comparison of microscopic and spectroscopic identification methods for analysis of microplastics in environmental samples.  

PubMed

The analysis of microplastics in various environmental samples requires the identification of microplastics from natural materials. The identification technique lacks a standardized protocol. Herein, stereomicroscope and Fourier transform infrared spectroscope (FT-IR) identification methods for microplastics (<1mm) were compared using the same samples from the sea surface microlayer (SML) and beach sand. Fragmented microplastics were significantly (p<0.05) underestimated and fiber was significantly overestimated using the stereomicroscope both in the SML and beach samples. The total abundance by FT-IR was higher than by microscope both in the SML and beach samples, but they were not significantly (p>0.05) different. Depending on the number of samples and the microplastic size range of interest, the appropriate identification method should be determined; selecting a suitable identification method for microplastics is crucial for evaluating microplastic pollution. PMID:25682567

Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Han, Gi Myung; Rani, Manviri; Lee, Jongmyoung; Shim, Won Joon

2015-04-15

353

Infrared laser-spectroscopic analysis of 14NO and 15NO in human breath  

NASA Astrophysics Data System (ADS)

We report on monitoring of nitric oxide (NO) traces in human breath via infrared cavity leak-out spectroscopy. Using a CO sideband laser near 5 ?m wavelength and an optical cavity with two high-reflectivity mirrors ( R=99.98%), the minimum detectable absorption is 2×10-10 cm-1 Hz1/2. This allows for spectroscopic analysis of rare NO isotopologues with unprecedented sensitivity. Application to simultaneous online detection of 14NO and 15NO in breath samples collected in the nasal cavity is described for the first time. We achieved a noise-equivalent detection limit of 7 parts per trillion for nasal 15NO (integration time: 70 s).

Heinrich, K.; Fritsch, T.; Hering, P.; Mürtz, M.

2009-05-01

354

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  

NASA Astrophysics Data System (ADS)

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 Csbnd C 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.

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

2015-01-01

355

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

356

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

357

Temperature-dependent vibrational spectroscopic study and DFT calculations of the sorbic acid  

NASA Astrophysics Data System (ADS)

This work reports a temperature-dependent vibrational spectroscopic study of the sorbic acid (C6H8O2), as well as the mode assignment at ambient conditions, based on the density functional theory. Temperature-dependent vibrational properties have been performed in polycrystalline sorbic acid through both Raman and infrared spectroscopy in the 20-300 K and 80-300 K temperature ranges, respectively. These studies present the occurrence of some modifications in the Raman spectra that could be interpreted as a low temperature phase transition undergone by sorbic acid from the monoclinic phase to an unknown phase with conformational change of the molecules in the unit cell.

Saraiva, G. D.; Nogueira, C. E. S.; Freire, P. T. C.; de Sousa, F. F.; da Silva, J. H.; Teixeira, A. M. R.; Mendes Filho, J.

2015-02-01

358

Spectroscopic studies on two mono nuclear iron (III) complexes derived from a schiff base and an azodye  

SciTech Connect

Two new mono nuclear Fe(III) complexes of an azodye (ANSN) and a Schiff base (FAHP) are reported. The azodye is prepared by coupling diazotized 1-amino-2-naphthol-4-sulphonicacid with 2-naphthol and the Schiff base is prepared by condensing 2-amino-3-hydroxy pyridine with furfural. The complexes were synthesized by the reaction of FeCl{sub 3}Ðœ‡2H{sub 2}O with respective ligands. They were characterized on the basis of elemental analysis and spectral studies like IR, NMR, Electronic and M.ssbauer. Magnetic susceptibility and Molar conductance of complexes at room temperature were studied. Based on the spectroscopic evidences and other analytical data the complexes are formulated as[Fe(ANSN)Cl(H{sub 2}O){sub 2}] and [Fe(FAHP)Cl{sub 2}(H{sub 2}O){sub 2}].

Mini, S., E-mail: sadasivan.v@gmail.com; Sadasivan, V., E-mail: sadasivan.v@gmail.com [University College, M G Road, Palayam, Thiruvananthapuram 695 034 Kerala (India); Meena, S. S., E-mail: ssingh@barc.gov.in; Bhatt, Pramod, E-mail: ssingh@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2014-10-15

359

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

360

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

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

361

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

362

SPECTROSCOPIC ANALYSIS OF AN EIT WAVE/DIMMING OBSERVED BY HINODE/EIS  

SciTech Connect

EUV Imaging Telescope (EIT) waves are a wavelike phenomenon propagating outward from the coronal mass ejection source region, with expanding dimmings following behind. We present a spectroscopic study of an EIT wave/dimming event observed by the Hinode/Extreme-ultraviolet Imaging Spectrometer. Although the identification of the wave front is somewhat affected by the pre-existing loop structures, the expanding dimming is well defined. We investigate the line intensity, width, and Doppler velocity for four EUV lines. In addition to the significant blueshift implying plasma outflows in the dimming region as revealed in previous studies, we find that the widths of all four spectral lines increase at the outer edge of the dimmings. We illustrate that this feature can be well explained by the field line stretching model, which claims that EIT waves are apparently moving brightenings that are generated by the successive stretching of the closed field lines.

Chen, F.; Ding, M. D.; Chen, P. F., E-mail: dmd@nju.edu.c [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

2010-09-10

363

The molecular structure of chloritoid: A mid-infrared and near-infrared spectroscopic study.  

PubMed

The mineral chloritoid collected from the argillite in the bottom of Yaopo Formation of Western Beijing was characterized by mid-infrared (MIR) and near-infrared (NIR) spectroscopy. The MIR spectra showed all fundamental vibrations including the hydroxyl units, basic aluminosilicate framework and the influence of iron on the chloritoid structure. The NIR spectrum of the chloritoid showed combination (?+?)OH bands with the fundamental stretching (?) and bending (?) vibrations. Based on the chemical component data and the analysis result from the MIR and NIR spectra, the crystal structure of chloritoid from western hills of Beijing, China, can be illustrated. Therefore, the application of the technique across the entire infrared region is expected to become more routine and extend its usefulness, and the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for the unit cell structural analysis. PMID:25828887

Li, Kuo; Liu, Qinfu; Cheng, Hongfei; Deng, Yutao; Frost, Ray L

2015-06-15

364

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

NASA Astrophysics Data System (ADS)

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

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

2005-02-01

365

The interaction of new piroxicam analogues with lipid bilayers--a calorimetric and fluorescence spectroscopic study.  

PubMed

The purpose of the present paper was to assess the ability of new piroxicam analogues to interact with the lipid bilayers. The results of calorimetric and fluorescence spectroscopic experiments of two new synthesized analogues of piroxicam, named PR17 and PR18 on the phase behavior of phospholipid bilayers and fluorescence quenching of fluorescent probes (Laurdan and Prodan), which molecular location within membranes is known with certainty, are shown in present work. The presented results revealed that, depending on the details of chemical structure, the studied compounds penetrated the lipid bilayers. PMID:25856831

Maniewska, Jadwiga; Szcz??niak-Si?ga, Berenika; Po?a, Andrzej; Sroda-Pomianek, Kamila; Malinka, Wies?aw; Michalak, Krystyna

2014-01-01

366

Spectroscopic Studies of Electronically Active Defects in Transition Metal Oxides for Advanced Si Devices  

SciTech Connect

Based on spectroscopic studies, and guided by ab initio theory, the electron and hole traps in HfO2 and other transition metal elemental oxides e.g., TiO2, are assigned to O-atom divacancies, clustered at internal grain boundaries. Engineering solutions for defect reduction are identified: (i) deposition of ultra-thin, < 2 nm HfO2 and phase separated Hf silicate dielectrics, in which grain boundary formation is suppressed by effectively eliminating inter-primitive unit cell {pi}-bonding interactions, and (ii) non-crystalline Zr/Hf Si oxynitrides without nanocrystalline grain boundaries.

Lucovsky, G.; Luning, J.

2009-06-04

367

Spectroscopic study of hydrogen Balmer lines in a microwave-induced discharge  

SciTech Connect

We present the results of a spectroscopic study of hydrogen Balmer line shapes and intensities in a microwave-induced discharge generated in an Evenson resonant cavity at 2.45 GHz in pure hydrogen and hydrogen-argon and hydrogen-helium gas mixtures. The Balmer line shapes do not show signs of excessive Doppler broadening. The discharge parameters-Doppler temperature (980 K), electron excitation temperature (1460-1790 K), and electron density of about 8x10{sup 11} cm{sup -3}--point to a typical microwave-induced discharge.

Jovicevic, S.; Sakan, N.; Ivkovic, M. [Institute of Physics, P.O. Box 68, 11081 Belgrade (Serbia); Konjevic, N. [Institute of Physics, P.O. Box 68, 11081 Belgrade (Serbia); Faculty of Physics, University of Belgrade, P.O. Box 368, 11000 Belgrade (Serbia)

2009-01-01

368

Spectroscopic and crystal field studies of (Ce,Gd)Sc3 (BO3)4:Cr3+ crystals  

NASA Astrophysics Data System (ADS)

Complex spectroscopic studies of (Ce,Gd)Sc3(BO3)4:Cr3+ (CSB:Cr3+) crystals (crystal growth, absorption and luminescence spectroscopy, crystal field calculations, analysis of the radiative and non-radiative decays) are presented. The main results of the paper include calculations of crystal field parameters and energy level scheme for Cr3+ at distorted octahedral Sc3+ sites, evaluation of the Huang Rhys factor, effective phonon frequency, zero-phonon line energy, and parameters of radiative and non-radiative decays. Comparison with experimental results and other literature data is discussed. A very unusual value of the frequency factor (related to the non-radiative processes) is explained as being due to heterodesmic nature of chemical bonds in the CSB crystal. Cr3+-doped CSB crystals (with Cr3+ concentration 5.1×1019 cm-3 or 1%) are suggested as promising candidates for potential applications as active media for solid state lasers.

Brik, M. G.; Lebedev, V. A.; Stroganova, E. V.

2007-09-01

369

Spectroscopic analysis of x-ray bursts from nichrome and conichrome X-pinch plasmas  

NASA Astrophysics Data System (ADS)

Radiative properties of plasmas from X pinches with nichrome and conichrome wires have been studied using the presented diagnostic arrangement. The experimental results have been produced at the Cornell XP facility with a peak current of 450 kA and a full width at half maximum pulse duration of 100 ns. The spatially resolved, time-integrated x-ray line spectra from the region of the X-pinch cross point have been recorded using different crystal spectrometers. In particular, K-shell and L-shell x-ray spectra of Ni and Cr have been recorded through different filters in the same pulses for X pinches from two different wire alloys. A nonlocal thermodynamic equilibrium collisional-radiative atomic kinetic model of Ni has been developed to identify the useful diagnostic spectroscopic features and to model experimental spectra. The results of the modeling and radiative properties of different materials from nichrome and conichrome alloys are compared and discussed.

Chandler, K. M.; Shlyaptseva, A. S.; Ouart, N. D.; Hansen, S. B.; Mitchell, M. D.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Kantsyrev, V. L.; Fedin, D. A.

2004-10-01

370

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

371

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

372

Ultraviolet spectroscopic study of EU UMa and ST LMi from HST and IUE observations  

NASA Astrophysics Data System (ADS)

We present the first orbit-resolved ultraviolet spectroscopic observations of the two polar systems EU UMa and ST LMi obtained with the Hubble Space Telescope Faint Object Spectrograph (HST FOS) and International Ultraviolet Explorer (IUE) during their intermediate- and low-luminosity states in the period between 1982 and 2003. Different line profiles of the two systems showing variations of line fluxes at different orbital phases are presented. This paper focuses on the C IV emission line at 1550 Å produced in the accretion stream, presenting calculations of spectral line fluxes, ultraviolet luminosities, and accretion rates for the two systems. Our analysis of the spectroscopic data reveals changes with orbital phase of the emission line profiles that correspond to the light curve variations of both EU UMa and ST LMi in the optical and infrared bands. The variations of line fluxes are attributed to variations of both density and temperature as a result of a changing rate of mass transfer from the secondary star to the white dwarf. The ultraviolet luminosity and accretion rate of EU UMa are smaller than the ultraviolet luminosity and accretion rate of ST LMi.

Sanad, M. R.; Bobrowsky, M.

2015-04-01

373

Electric and spectroscopic analysis of a pure nitrogen mono-filamentary dielectric barrier discharge (MF-DBD) at 760 Torr  

NASA Astrophysics Data System (ADS)

Mono-filamentary dielectric barrier discharge (MF-DBD), occurring within 1 mm gap of atmospheric pressure pure nitrogen and operating with a sinusoidal electric supply at about 8 kHz, is studied in this paper. A thorough electrical analysis allows experimental determination of the ignition and extinction voltages, respectively (15 750 ± 50) V and (2097 ± 7) V, the injected energy (158 ± 2) J and charge (17.22 ± 0.22) nC in a single filament. The mean axial reduced electric field is equal to (644 ± 2) Td at ignition. An empirical technique is proposed to evaluate these discharge parameters by avoiding bulky calculations. Optical emission spectroscopic measurements of the vacuum ultraviolet (VUV), ultraviolet (UV), visible and near infrared (IR) emissions are presented and discussed. Two atomic nitrogen lines attributed to the decay of the N[2s2p23s 2P] triplet towards N[2s22p3 2D°] level are observed at 150 and 175 nm, together with the Lyman-Birge-Hopfield system (N_{2}[a\\,{}^1\\Pi_g ]\\to N_2 [X\\,{}^1\\Sigma_g^+ ]) in the VUV range. The second positive system (N2[C 3?u] ? N2[B 3?g]) dominates the UV and visible-blue spectra. The (0-0) transition of the first negative system (N_2^+ [B\\,{}^2\\Sigma_u^+ ]\\to N_2^+ [X\\,{}^2\\Sigma_g^+ ]) peaking at 391.4 nm, the first positive system (N_{2}[B\\,{}^3\\Pi_g ]\\to N_2 [A\\,{}^3\\Sigma_u^+ ]) and the Herman IR transitions (N_{2}[C''\\,{}^5\\Pi_u ]\\to N_2 [A'\\,{}^5\\Sigma_g^+ ]) are also present. Both our VUV and near IR spectra are consistent with recently reported results in hollow cathode and cylindrical DBDs. The electrical and spectroscopic experimental results reported here are useful for ongoing and forthcoming modelling of filamentary nitrogen dielectric barrier discharges.

Sewraj, N.; Merbahi, N.; Gardou, J. P.; Rodriguez Akerreta, P.; Marchal, F.

2011-04-01

374

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

375

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

376

Spectroscopic and TSDC analysis of 100 MeV Ag ion irradiated polyetherimide  

NASA Astrophysics Data System (ADS)

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

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

377

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

378

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

379

Structural, spectroscopic (FT-IR, FT-Raman and UV) studies, HOMO-LUMO, NBO, NLO analysis and reactivity descriptors of 2,3 Difluoroaniline and 2,4-Difluoroaniline  

NASA Astrophysics Data System (ADS)

Complete vibrational analysis of the fundamental modes of 2,3-Difluoroaniline and 2,4-Difluoroaniline has been carried out using theoretical and experimental FTIR as well as FT-Raman spectral data and compared to reveal the effect of substituted F atoms on aromatic ring. Comprehensive investigation of geometrical and electronic structure in ground as well as the first excited state of both molecules has been performed. UV-Vis spectra of the title compounds were also recorded and the electronic properties, such as frontier orbitals and band gap energies were calculated by TD-DFT approach. DOS, OPDOS, natural atomic charges, molecular electrostatic potential surface and thermo-dynamical properties have been calculated to get a better insight of the properties of the title compounds. Non-linear optical properties such as dipole moment, polarizability, first static hyperpolarizability were also calculated to predict their NLO behavior. Stability of the compounds arising from hyper-conjugative interaction and charge delocalization has been analyzed using Natural bond orbital (NBO) analysis. Global and local reactivity descriptors have been computed to predict reactivity and reactive sites on the molecules.

Pathak, Shilendra K.; Haress, Nadia G.; El-Emam, Ali A.; Srivastava, Ruchi; Prasad, Onkar; Sinha, Leena

2014-09-01

380

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

SciTech Connect

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

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

2013-01-15

381

Spectroscopic study of emission coal mineral plasma produced by laser ablation  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

382

Spectroscopic study and structure of (E)-2-[(2-chlorobenzylimino)methyl]methoxyphenol.  

PubMed

(E)-2-[(2-chlorobenzylimino)methyl]methoxyphenol has been synthesized from the reaction of 2-hydroxy-3-methoxy-1-benzaldehyde(o-vanillin) with 2-chlorobenzylamine. The title compound has been characterized by using elemental analysis, FT-IR, (1)H NMR, (13)C NMR and UV-vis spectroscopic techniques. The crystal structure of the title compound has also been examined cyrstallographically. It crystallizes in the orthorhombic space group Pbca with unit cell parameters: a = 7.208(1) A, b = 13.726(2) A, c = 27.858(4) A, V = 2756.0(1) A(3), D(c) = 1.18 g cm(-3) and Z = 8. The crystal structure was solved by direct methods and refined by full-matrix least squares to a find R = 0.046 for 2773 observed reflections. PMID:19879183

Unver, Hüseyin; Yildiz, Mustafa; Ozay, Hava; Durlu, Tahsin Nuri

2009-12-01

383

X-ray spectroscopic study of the largest X-ray selected spectroscopic AGN sample in the XMM-XXL north  

NASA Astrophysics Data System (ADS)

The XMM-XXL survey is a large public XMM survey which covers two ˜25 deg^2 sky regions with rich multi-wavelength coverage. In the northern field, we have extracted about ˜8000 unique point-like sources, identified their optical counterparts in SDSS imaging, and obtained spectroscopic redshift for ˜2400 AGN (with high completeness down to r-band optical magnitude of r˜22) thanks to a dedicated ancillary program of the SDSS-III/BOSS survey. This is to date the largest contiguous X-ray selected AGN sample with spectroscopic redshift information. Here we present the overall X-ray spectral properties of these ˜2400 reliable AGN. We fitted each X-ray spectrum with a simple power law model, modified by Galactic and intrinsic absorption. By dividing the sample into different redshift and luminosity bins, it possible to study the average X-ray spectrum properties of AGN in different cosmic epoch. We can also study the correlations between the X-ray spectrum and the optical spectrum parameters, and how those correlations change with redshift and the other physical parameters of the source (e.g. BH mass, accretion disc luminosity, broad emission line shapes etc.). Using the X-ray spectrum stacking method, we also study the properties of the iron K line in different redshift and luminosity bins.

Liu, Z.; Merloni, A.; Georgakakis, A.; Menzel, M.; Buchner, J.; Nandra, K.

2014-07-01

384

Development of an infrared spectroscopic approach for studying metalloenzyme active site chemistry under direct electrochemical control.  

PubMed

Direct electrochemical methods have been productive in revealing mechanistic details of catalysis by a range of metalloenzymes including hydrogenases and carbon and nitrogen cycling enzymes. In this approach, termed protein film electrochemistry, the protein is attached or adsorbed on the electrode surface and exchanges electrons directly, providing precise control over redox states or catalysis and avoiding diffusion-limited electron transfer. The 'edge' surface of pyrolytic graphite has proved to be a particularly good surface for adsorption of proteins in electroactive conformations. We now describe development of an approach that combines the precise control achieved in direct electrochemical measurements at a graphite electrode with surface infrared (IR) spectroscopic analysis of chemistry occurring at metallocentres in proteins. Hydrogenases are of particular interest: their unusual organo-metallic active sites--iron or nickel-iron centres coordinated by CO and CN(-)--give rise to IR v(CO) and v(CN) bands that are detected readily because these ligands are strong vibrational oscillators and are sensitive to changes in electron density and coordination at the metals. Small diatomic species also bind as exogenous ligands (as substrate, product, activator or inhibitor) to a range of other important metalloproteins, and understanding their reactivity and binding selectivity is critical in building up a multidimensional picture of enzyme chemistry and evolutionary history. The surface IR spectroelectrochemical approach we describe is based around Attenuated Total Reflectance (ATR) mode sampling of a film of pyrolytic graphite particles modified with a protein of interest. The particle network extends the electrode into three-dimensional space, providing sufficient adsorbed protein for spectroscopic analysis under precise electrochemical control. This strategy should open up new opportunities for detection of redox-dependent chemistry at metal centres in proteins, including short-lived catalytic intermediates and time-resolved details of catalysis and inhibition. PMID:21322492

Healy, Adam J; Reeve, Holly A; Vincent, Kylie A

2011-01-01

385

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

NASA Astrophysics Data System (ADS)

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

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

1998-03-01

386

Quantum mechanical study of the structure and spectroscopic (FT-IR, FT-Raman, 13C, and 1H) and HOMO-LUMO analysis of 2,4-dimethoxy benzaldehyde (DMBA) and 4-methoxy-3-methyl benzaldehyde (MMBA)  

NASA Astrophysics Data System (ADS)

The present communication is aimed at comparing the molecular structural properties, vibrational and energetic data of 2,4-dimethoxy benzaldehyde and for 4-methoxy-3-methyl benzaldehyde, due to their commercial importance. The ground state properties of the title molecules have been calculated employing DFT/B3LYP level of theory using the 6-31G (d) basis set. In order to obtain a complete description of molecular dynamics, vibrational wavenumber calculation along with the normal mode analysis, have been carried out at the DFT level. The calculated spectra of both the molecules agree well with the experimental data. The 1H and 13C NMR spectra have been simulated using the gauge independent atomic orbital (GIAO) method. The electronic properties, such as HOMO, LUMO energies, absolute electronegativity X and absolute hardness ? were performed by DFT approach. The first order hyperpolarizability (?o) of these novel molecular system and related properties (?, ?o and ??) of DMBA and MMBA are calculated using DFT/6-31G (d) method on the finite-field approach.

KrishnaKumar, V.; Barathi, D.; Mathammal, R.

2013-03-01

387

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

NASA Astrophysics Data System (ADS)

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

Hopp, U.; Vennik, J.

2014-11-01

388

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

389

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

390

Embedded spectroscopic fiber sensor for on-line arc-welding analysis.  

PubMed

A new fiber sensor system designed for spectroscopic analysis and on-line quality assurance of arc-welding processes is presented here. Although several different approaches have been considered for the optical capture of plasma emission in arc-welding processes, they tend to be invasive and make use of optical devices such as collimators or photodiodes. The solution proposed here is based on the arrangement of an optical fiber, which is used at the same time as the optical capturing device and also to deliver the optical information to a spectrometer, embedded within an arc-welding torch. It will be demonstrated that, by using the shielding gas as a protection for the fiber end, the plasma light emission is efficiently collected, forming a sensor system completely transparent and noninvasive for the welding operator. The feasibility of the proposed sensor designed to be used as the input optics of a welding quality-assurance system based on plasma spectroscopy will be demonstrated by means of several welding tests. PMID:17514278

Mirapeix, Jesús; Cobo, Adolfo; Quintela, Antonio; López-Higuera, José-Miguel

2007-06-01

391

Ascidian (Chordata-Tunicata) glycosaminoglycans: extraction, purification, biochemical, and spectroscopic analysis.  

PubMed

Sulfated polysaccharides with unique structures of the chondroitin/dermatan and heparin/heparan families of sulfated glycosaminoglycans have been described in several species of ascidians (Chordata-Tunicata). These unique sulfated glycans have been isolated from-ascidians and characterized by biochemical and spectroscopic methods. The ascidian glycans can be extracted by different tissues or cells by proteolytic digestion followed by cetylpyridinium chloride/ethanol precipitation. The total glycans are then fractionated by ion-exchange chromatography on DEAE-cellulose and/or Mono Q (HR 5/5) columns. Alternatively, precipitation with different ethanol concentrations can be employed. An initial analysis of the purified ascidian glycans is carried out by agarose gel electrophoresis on diaminopropane/acetate buffer, before or after digestion with specific glycosaminoglycan lyases or deaminative cleavage with nitrous acid. The disaccharides formed by exhaustive degradation of the glycans is purified by gel-filtration chromatography on a Superdex-peptide column and analyzed by HPLC on a strong ion exchange Sax-Spherisorb column. 1H or 13C nuclear magnetic resonance spectroscopy in one or two dimensions is used to confirm the structure of the intact glycans. PMID:25325946

Pavão, Mauro S G

2015-01-01

392

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

393

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

394

Spectroscopic-Photometric Analysis of the Binary System V4089 Sagitarii  

NASA Astrophysics Data System (ADS)

We present an observational analysis of the eclipsing double-lined spectroscopic binary HR 7422=V4089 Sgr. Nineteen spectra were obtained with the 2.15 m telescope and the bench echelle spectrograph EBASIM of the CASLEO observatory, while photometric observations in the Johnson V band were carried out with the 61 cm telescope at CASLEO. We measured radial velocities to a precision of 0.45 km s^-1 for both stellar components using the method of separation of composite spectra by González & Levato (2006, A&A, 448, 283). From light and radial velocity curves we derived orbital and physical parameters for the system using the Wilson & Devinney code. With this aim, our light curve was complemented with the photometry in the V band of the Geneva system published by North et al. (1997, A&A, 324, 137). We obtained masses and radii to a precision of 0.45% and 0.9%, respectively. The system V4089 Sgr is very useful to test stellar models due to the great difference between the components. The comparison with theoretical stellar models of Lejeune & Schaerer (2001, A&A, 366, 538) suggest an age of log ? = 8.695+/-0.007. Since the primary is close to the TAMS, we used this system to compare the predictions of standard and overshooting models.

Veramendi, M. E.; González, J. F.

2009-05-01

395

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

396

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

NASA Astrophysics Data System (ADS)

This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph2Tz) and some oligomeric derivatives. Ph2Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV-Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

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

2012-10-01

397

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

398

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

PubMed

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. PMID:14583293

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

2003-11-01

399

Behind the reactivity of lactones: a computational and spectroscopic study of phenol·?-butyrolactone.  

PubMed

In this work, the intermolecular interaction between phenol and ?-butyrolactone (GBL) has been studied by a combination of spectroscopic and computational techniques. The electronic and vibrational transitions of phenol · GBL were measured in a supersonic jet expansion by resonant two-photon ionization (R2PI) and ion dip IR (IDIR) spectroscopy. The results obtained were compared with calculations carried out with both M06-2X and MP2 molecular orbital methods in order to characterize the intermolecular interactions. The singly detected conformer is stabilized by a relatively strong hydrogen bond in which phenol acts as a proton donor to the carbonyl group of GBL. The phenol · GBL2 cluster has also been studied, finding up to three populated conformers. Nevertheless, in the three species, the main interaction between the phenolic hydroxyl group and the GBL's carbonyl group remains similar to that of phenol · GBL. Furthermore, the C ? O · · · H interaction is reinforced. PMID:24678986

León, Iker; González, Jorge; Millán, Judith; Castaño, Fernando; Fernández, José A

2014-04-10

400

Laser performance and spectroscopic analysis of optically written channel waveguides in neodymium-doped gallium lanthanum sulphide glass  

Microsoft Academic Search

We present a spectroscopic analysis and laser characterization of optically written waveguides in neodymium-doped gallium lanthanum sulphide (Nd3+-Ga:La:S) chalcogenide glass. Uniform channel waveguides were fabricated in Nd3+-Ga:La:S by exposure to radiation from a focused UV-laser beam (?=244 nm), producing a refractive index change ▵n?+10-3. The observed laser performance and fluorescence decay were in good agreement with values calculated from a

Arshad K. Mairaj; Alain M. Chardon; David P. Shepherd; Daniel W. Hewak

2002-01-01

401

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

402

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

403

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

404

Analysis of interaction between tamoxifen and ctDNA in vitro by multi-spectroscopic methods.  

PubMed

Multi-spectroscopic methods including resonance light scattering (RLS), ultraviolet spectra (UV), fluorescence spectra, (1)H NMR spectroscopy, coupled with thermo-denaturation experiments were firstly used to study the interaction of antitumor drug tamoxifen (TMX) with calf thymus (ctDNA) in acetate buffer solutions (pH 4.55). The interaction of TMX with ctDNA could cause a significant enhancement of RLS intensity, the hyperchromic effect, red shift of absorption spectra and the fluorescence quenching of TMX, indicating that there is an inserting interaction between TMX and ctDNA. This inference was confirmed by (1)H NMR spectroscopy. The chemical shift of the benzene proton changes significantly which indicates that TMX could insert into the base pairs of ctDNA. These studies are valuable for a better understanding the mode of TMX-ctDNA interaction further, which are important and useful for designing of new ctDNA targeted drug. And the antitumor drug TMX inserted directly into ctDNA in vitro, which can provide a lot of useful information to explore the development of new and highly effective anti-cancer drugs. PMID:20392665

Cai, Changqun; Chen, Xiaoming; Ge, Fei

2010-07-01

405

Analysis of interaction between tamoxifen and ctDNA in vitro by multi-spectroscopic methods  

NASA Astrophysics Data System (ADS)

Multi-spectroscopic methods including resonance light scattering (RLS), ultraviolet spectra (UV), fluorescence spectra, 1H NMR spectroscopy, coupled with thermo-denaturation experiments were firstly used to study the interaction of antitumor drug tamoxifen (TMX) with calf thymus (ctDNA) in acetate buffer solutions (pH 4.55). The interaction of TMX with ctDNA could cause a significant enhancement of RLS intensity, the hyperchromic effect, red shift of absorption spectra and the fluorescence quenching of TMX, indicating that there is an inserting interaction between TMX and ctDNA. This inference was confirmed by 1H NMR spectroscopy. The chemical shift of the benzene proton changes significantly which indicates that TMX could insert into the base pairs of ctDNA. These studies are valuable for a better understanding the mode of TMX-ctDNA interaction further, which are important and useful for designing of new ctDNA targeted drug. And the antitumor drug TMX inserted directly into ctDNA in vitro, which can provide a lot of useful information to explore the development of new and highly effective anti-cancer drugs.

Cai, Changqun; Chen, Xiaoming; Ge, Fei

2010-07-01

406

Raman spectroscopic analysis of geological and biogeological specimens of relevance to the ExoMars mission.  

PubMed

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. PMID:23758166

Edwards, Howell G M; Hutchinson, Ian B; Ingley, Richard; Parnell, John; Vítek, Petr; Jehli?ka, Jan

2013-06-01

407

Spectroscopic, structural, computational and (spectro)electrochemical studies of icosahedral carboranes bearing fluorinated aryl groups.  

PubMed

The icosahedral carboranes 1-C(6)F(5)-2-Ph-1,2-closo-C(2)B(10)H(10) (1), 1-(4'-F(3)CC(6)H(4))-2-Ph-1,2-closo-C(2)B(10)H(10) (2), 1,2-(4'-F(3)CC(6)H(4))(2)-1,2-closo-C(2)B(10)H(10) (3), 1-(4'-H(3)CC(6)F(4))-2-Ph-1,2-closo-C(2)B(10)H(10) (4), 1-(4'-F(3)CC(6)F(4))-2-Ph-1,2-closo-C(2)B(10)H(10) (5), 1,2-(4'-F(3)CC(6)F(4))(2)-1,2-closo-C(2)B(10)H(10) (6), 1,7-(4'-F(3)CC(6)F(4))(2)-1,7-closo-C(2)B(10)H(10) (7) and 1,12-(4'-F(3)CC(6)F(4))(2)-1,12-closo-C(2)B(10)H(10) (8), with fluorinated aryl substituents on cage carbon atoms, have been prepared in good to high yields and characterised by microanalysis, (1)H, (11)B and (19)F NMR spectroscopies, mass spectrometry, single-crystal X-ray diffraction and (spectro)electrochemistry. By analysis of , the weighted average (11)B chemical shift, a ranking order for the ortho carboranes 1-6 is established based on the combined electron-withdrawing properties of the C-substituents, and is in perfect agreement with that established independently by electrochemical study. In a parallel computational study the effects of a wide range of different substituents on the redox properties of carboranes have been probed by comparison of ?E values, where ?E is the energy gap between the DFT-optimised [7,9-R(2)-7,9-nido-C(2)B(10)](2-) anion and its DFT-optimised basket-shaped first oxidation product. The overall conclusion from the NMR spectroscopic, electrochemical and computational studies is that strongly electron withdrawing substituents significantly stabilise [7,9-nido-C(2)B(10)](2-) dianions with respect to oxidation, and that the best practical substituent is 4-F(3)CC(6)F(4). Thus attention focussed on the reduction of 1,2-(4'-F(3)CC(6)F(4))(2)-1,2-closo-C(2)B(10)H(10), compound 6. The sequence 6/[6](-)/[6](2-) appears reversible on the cyclic voltammetric timescale but on the longer timescale of macroelectrolysis the radical anion is only partially stable. EPR study of the electrogenerated monoanions from the ortho-carboranes 1-6 confirms the cage-centred nature of the redox processes. In contrast, the reduction of the meta- and para-carboranes 7 and 8, respectively, appears to be centred on the aromatic substituents, a conclusion supported by the results of DFT calculation of the LUMOs of compounds 6-8. Bulk 2-electron reduction of 6 affords a dianion which is remarkably stable to reoxidation, surviving for several hours in the open laboratory in the absence of halogenated solvents. PMID:21390395

Tricas, Hugo; Colon, Marta; Ellis, David; Macgregor, Stuart A; McKay, David; Rosair, Georgina M; Welch, Alan J; Glukhov, Ivan V; Rossi, Fulvio; Laschi, Franco; Zanello, Piero

2011-04-28

408

Spectroscopic and thermodynamic studies on the binding of gadolinium(III) to human serum transferrin  

SciTech Connect

A wide variety of thermodynamic, kinetic, and spectroscopic studies have demonstrated differences between the two metal-binding sites of transferrin. In the present investigation, the authors have further assessed these differences with respect to the binding of gadolinium, evaluated by UV difference spectrophotometry, electron paramagnetic resonance (EPR) titration, EPR difference spectroscopy in conjunction with urea gel electrophoresis, and equilibrium dialysis. Combinations of these studies establish that only one site of the protein binds Gd(III) sufficiently firmly to be characterized. In order to reveal which of the two sites accepts Gd(III), we made use of monoferric transferrins preferentially loaded with Fe(III) at either site in EPR spectroscopic studies. Because of the overlap of signals, difference spectroscopy was required to distinguish resonances arising from Fe(III) and Gd(III) specifically complexed to the protein. When iron is bound to the C-terminal site, leaving the N-terminal site free for binding of gadolinium, the difference spectrum shows no evidence of specific binding. However, when iron is bound to the N-terminal site, the difference spectrum shows a resonance line at g' = 4.1 indicative of specific binding, thus implicating the C-terminal site in the binding of Gd(III). The effective stability constant for the binding of Gd(III) to this site of transferrin at pH 7.4 and ambient pCO/sub 2/ is 6.8 x 10/sup 6/ M/sup -1/. At physiological pCO/sub 2/, the formation of nonbinding carbonato complexes of Gd(III) precludes a substantial role from transferrin in the transport of the lanthanide in vivo.

Zak, O.; Aisen, P.

1988-02-09

409

3, 40374067, 2003 FTIR spectroscopic  

E-print Network

ACPD 3, 4037­4067, 2003 FTIR spectroscopic studies I. Xueref and F. Domin´e Title Page Abstract/4037/ © European Geosciences Union 2003 Atmospheric Chemistry and Physics Discussions FTIR spectroscopic studies@io.harvard.edu) 4037 #12;ACPD 3, 4037­4067, 2003 FTIR spectroscopic studies I. Xueref and F. Domin´e Title Page

Paris-Sud XI, Université de

410

Structures and spectroscopic studies of indolecarboxylic acids. Part III. Diamminetetrakis-?-(O,O?-indole-3-carboxylate)dicopper(II)  

NASA Astrophysics Data System (ADS)

The crystal and molecular structures of the novel compound diamminetetrakis-?-( O, O'-indole-3-carboxylate)dicopper(II), Cu-I3CA, have been determined using single-crystal X-ray diffraction, infrared spectroscopy and EPR methods. The crystals are monoclinic, space group P2 1/c, with a=9.505(2), b=7.469(1), c=23.779(5), V=1669.1(6) Å 3 and Z=2. Complex has a dinuclear molecular structure of C i symmetry in which the carboxyl groups of the indole-3-carboxylic acid ligands act as bridges. The Cu-Cu distance of 2.6387(8) Å, Cu-O distances of 1.961(2) and 1.970(2) Å, and Cu-NH 3 distance of 2.188(2) Å, are typical of such dinuclear complexes. The novel Cu-I3CA complex unit reveals a remarkable similarity in its structural and spectroscopic features to the Cu(II) complexes of the human anti-inflammatory drug, indomethacin (a derivative of indole-3-acetic acid). The EPR and infrared spectroscopic studies of Cu-I3CA in the solid state well support the results from X-ray analysis. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the O-deprotonated indole-3-carboxylate ion (I3CA -) have been calculated using density functional (B3LYP) method with the 6-311++G(d,p) basis set. The potential energy distribution (PED) calculated for the ionic ligand (I3CA -) has proved to be of great help in assigning the infrared spectrum of the title complex. The results from natural bond orbital (NBO) analyses for I3CA - and indole-3-carboxylic acid (I3CA) are discussed.

Morzyk-Ociepa, Barbara; Rozycka-Sokolowska, Ewa

2006-02-01

411

Cortical mapping of gait in humans: a near-infrared spectroscopic topography study.  

PubMed

While we have a fair understanding of how and where forelimb-hand manipulative movements are controlled by the neocortex, due to functional imaging studies, we know little about the control of bipedal movements such as walking because of technical difficulties. We succeeded in visualizing cortical activation patterns of human gait by measuring relative changes in local hemoglobin oxygenation using a recently developed near-infrared spectroscopic (NIRS) topography technique. Walking activities were bilaterally associated with increased levels of oxygenated and total hemoglobin in the medial primary sensorimotor cortices and the supplementary motor areas. Alternating foot movements activated similar but less broad regions. Gait imagery increased activities caudally located in the supplementary motor areas. These findings provide new insight into cortical control of human locomotion. NIRS topography might be also useful for evaluating cerebral activation patterns during pathological gait and rehabilitative intervention. PMID:11697950

Miyai, I; Tanabe, H C; Sase, I; Eda, H; Oda, I; Konishi, I; Tsunazawa, Y; Suzuki, T; Yanagida, T; Kubota, K

2001-11-01