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1

Rapid Flow Analysis Studies with Spectroscopic Detectors  

Microsoft Academic Search

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

Amlius Thalib

1984-01-01

2

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

3

Vibrational spectroscopic analysis of an amber necklace—a forensic historical study  

Microsoft Academic Search

The vibrational infrared spectroscopic analysis of an important historical necklace of 102 beads that are purported to be\\u000a made of amber indicated strong signal characteristics of cellulose nitrate with dark green-coloured areas of a naphthylamine\\u000a dye. Confocal Raman depth-profiling spectroscopy using a 785-nm laser excitation, a novel application first applied here for\\u000a the analysis of inclusions in amber resin, confirmed

Howell G. M. Edwards

2010-01-01

4

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

5

Vibrational spectroscopic analysis of an amber necklace--a forensic historical study.  

PubMed

The vibrational infrared spectroscopic analysis of an important historical necklace of 102 beads that are purported to be made of amber indicated strong signal characteristics of cellulose nitrate with dark green-coloured areas of a naphthylamine dye. Confocal Raman depth-profiling spectroscopy using a 785-nm laser excitation, a novel application first applied here for the analysis of inclusions in amber resin, confirmed that the beads were amber resin and that residues of cellulose nitrate, camphor plasticiser and a naphthylamine dyestuff were present in surface cracks and inclusions in the bead matrix. The bead stringing material was confirmed as cellulose, which was stained green in part with the dyestuff. Comparison of the Raman spectra of the amber beads with a resin database suggested that the amber was sourced from Northern England. The scientific evidence supports the stylistic opinion that the necklace is an important example that could date from the 19th Century and that efforts had been made to coat it with a synthetic dyed polymer; this provides a rather unusual example of the chemical masking of a genuine article--a procedure that renders the article of particular interest. PMID:20376434

Edwards, Howell G M

2010-04-08

6

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

7

[Infrared spectroscopic study on the component and vigor analysis of Cistanche deserticola seeds].  

PubMed

Comparative study of the different parts of cistanche deserticola seeds and their changes after different processing were examined by Fourier transform infrared spectroscopy spectra (FTIR). The results of the analysis showed that components in the cistanche deserticola seeds were abundant, which contained characteristic absorption peaks of protein, fat and carbohydrate. As well, pectin and aromatic compound can be also found in the seeds. However, the components were different in different parts of cistanche deserticola seeds. The characteristic absorption peak intensities of fat at 2,926, 1,746, 1,161 and 721 cm(-1) were the strongest in the seed kernels. However, the seed coats mainly consisted of carbohydrate and pectin, which were showed at 1,054 cm(-1). The contents of protein and carbohydrate were decreased distinctly in the moldy and dead seeds after processing. The characteristic absorption peak intensity ratio of protein to fat (I1,630/I1,745 ) was all higher than 1.05 in the live seeds. The characteristic absorption peak intensity ratio of amido link I of protein to fat (11,653/I1,745) in the dead seed kernels of the cistanche deserticola was decreased from 0.31 to 0. 23, which was 25.8% less than that in vital seed kernels. The results suggest that FTIR not only can be used in fast comprehensive analysis of seed components, but also can be used in the seed vigor analysis, seed longevity determination and seed quality evaluation. PMID:19385214

Xu, Rong; Sun, Su-Qin; Chen, Jun; Chen, Shi-Lin; Zhou, Feng

2009-01-01

8

Spectroscopic-speckle variance OCT for microvasculature detection and analysis  

PubMed Central

We propose and studied optical coherence tomography (OCT) combining spectroscopic (SOCT) and speckle variance (svOCT) functions to effectively detect locations of microvasculatures and assess blood oxygen saturation level. Chorioallantoic membrane of a chick embryo was imaged in vivo to perform the analysis of the system. We also studied the effect of speckle in spectral domain using experimental data and performed time-averaging to reduce speckle noise locally. We combined SOCT and svOCT images using hue, saturation and value (HSV) color map to show the localized spectroscopic property of blood. Results show distinct spectroscopic properties between arterial blood and capillary blood.

Liu, Xuan; Zhang, Kang; Huang, Yong; Kang, Jin U.

2011-01-01

9

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

NASA Astrophysics Data System (ADS)

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

?miechowski, Maciej

2011-08-01

10

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

PubMed

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

?miechowski, Maciej

2010-09-01

11

Natural bond orbital analysis and vibrational spectroscopic studies of H-bonded N,N?-diphenylguanidinium nitrate  

NASA Astrophysics Data System (ADS)

NIR-FT Raman and FT-IR spectra of the crystallized biologically active molecule N,N?-diphenylguanidinium nitrate (DGN) have been recorded and analyzed using quantum chemical computations based on density functional theory. The extraordinary basicity and strong stability of this novel bioactive compound has been discussed as the consequence of resonance stabilization leading to Y-aromaticity and hydrogen bonding. This peculiar Y-delocalization character of DGN is well reflected in the optimized geometry and bond order (BO) calculations. The observance of the equality of C N bond lengths in the protonated species indicates delocalization of the ?-electron system. The spectroscopic and natural bonds orbital (NBO) analysis confirms the occurrence of strong network of inter molecular hydrogen bonds. The changes in electron density in the global minimum and in the energy of hyperconjugative interactions of DGN calculated by second order perturbation theory have been studied extensively in comparison with the values of the neutral species. The observed characteristic ring vibrations are well fit with the theoretical values calculated at B3LYP/6-31G? level.

James, C.; Jayakumar, V. S.; Hubert Joe, I.

2007-03-01

12

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

2012-02-01

13

A spectroscopic study of southern (candidate) ? Doradus stars. II. Detailed abundance analysis and fundamental parameters  

NASA Astrophysics Data System (ADS)

Context: The ? Doradus stars are a recent class of variable main sequence F-type stars located on the red edge of the Cepheid instability strip. They pulsate in gravity modes, and this makes them particularly interesting for detailed asteroseismic analysis, which can provide fundamental knowledge of properties near the convective cores of intermediate-mass main sequence stars. Aims: To improve current understanding of ? Dor stars through theoretical modelling, additional constraints are needed. Our aim is to estimate the fundamental atmospheric parameters and determine the chemical composition of these stars. Detailed analyses of single stars have previously suggested links to Am and ? Boo stars, so we wish to explore this interesting connection between chemical peculiarity and pulsation. Methods: We analysed a sample of ? Dor stars for the first time, including nine bona fide and three candidate members of the class. We determined the fundamental atmospheric parameters and compared the abundance pattern with other A-type stars. We used the semi-automatic software package VWA for the analysis. This code relies on the calculation of synthetic spectra and thus takes line-blending into account. This is important because of the fast rotation in some of the sample stars, and we made a thorough analysis of how VWA performs when increasing v sin i. We obtained good results in agreement with previously derived fundamental parameters and abundances in a few selected reference stars with properties similar to the ? Dor stars. Results: We find that the abundance pattern in the ? Dor stars is not distinct from the constant A- and F-type stars we analysed. Appendices A and B are only available in electronic form at http://www.aanda.org

Bruntt, H.; De Cat, P.; Aerts, C.

2008-02-01

14

The Spectroscopic study of {sup 33}Ar  

SciTech Connect

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

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

2011-10-28

15

Depolarized light scattering spectroscopic study of OTP dynamics above Tg: a mode coupling analysis approach  

NASA Astrophysics Data System (ADS)

The dynamics of ortho-terphenyl (OTP) was studied using a Tandem-Fabry-Perot interferometer (FPI) and a grating monochromator. The results were analyzed using the mode coupling approach. The scaling laws predicted in this theory were partly confirmed.

Steffen, W.; Meier, G.; Patkowski, A.; Fischer, E. W.

1993-12-01

16

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

17

Spectroscopic and vibrational analysis of the methoxypsoralen system: A comparative experimental and theoretical study  

NASA Astrophysics Data System (ADS)

Raman spectra measurements and density functional theory (DFT) calculations were performed to investigate three psoralens: 5-amino-8-methoxypsoralen (5-A-8-MOP), 5-methoxypsoralen (5-MOP) and 8-methoxypsoralen (8-MOP) with the aim of differentiating these similar bioactive molecules. The Raman spectra were recorded in the region 300-3500 cm-1. All three psoralens were found to have similar Raman spectrum in the region 1500-1650 cm-1. 5-A-8-MOP can be easily differentiated from 5-MOP or 8-MOP based on the Raman spectrum. The Raman spectrum differences at 651 and 795 cm-1 can be used to identify 5-MOP from 8-MOP. The theoretically computed vibrational frequencies and relative peak intensities were compared with experimental data. DFT calculations using the B3LYP method and 6-311++G(d,p) basis set were found to yield results that are very comparable to experimental Raman spectra. Detailed vibrational assignments were performed with DFT calculations and the potential energy distribution (PED) obtained from the Vibrational Energy Distribution Analysis (VEDA) program.

Liu, Y.; Yuan, H.; Vo-Dinh, T.

2013-03-01

18

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

19

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

20

Spectroscopic Techniques for Atmospheric Analysis  

SciTech Connect

Several analytical and optical techniques for atmospheric analysis are discussed. Environmental constraints for real world applications are mentioned. Special emphasis is given to the cavity ring Down Spectroscopy as a very sensitive method for atmospheric trace gas detection is described.

Bililign, Solomon [Department of Physics, North Carolina Agricultural and technical state University Greensboro, NC 27411 (United States)

2009-07-06

21

Spectroscopic Methods of Steroid Analysis  

NASA Astrophysics Data System (ADS)

Modern chemical laboratories contain equipment capable of measuring many of the physical properties of single chemical compounds and mixtures of compounds, particularly their spectral properties, which can, if interpreted correctly, provide valuable information about both structure (of single compounds) and composition (of mixtures). Over the past 50 years, the author have witnessed enormous progress in the technical capabilities of this equipment. Automation and speed of analysis have greatly improved the ease of use and the versatility of the technology.

Kasal, Alexander; Budesinsky, Milos; Griffiths, William J.

22

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

PubMed

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

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

2012-09-24

23

Spectroscopic analysis of irradiated erythrocytes  

NASA Astrophysics Data System (ADS)

The aim of the present work is to study the effect of gamma radiation on the lipid part of the erythrocyte membrane, and to test the efficiency of lipoic acid as a radioprotector. This effect was evaluated using electron paramagnetic resonance (EPR), and Fourier transform infrared (FT-IR) spectroscopy. The results showed an increase in the number of spin density by 14%, 22% and 65% after exposure to 25, 50 and 100 Gy respectively; whereas there was a decline in the obtained density after incubation with lipoic acid by a factor of approximately 32%. The FT-IR spectra of the irradiated erythrocytes samples showed a marked decrease in the intensity of all characteristic peaks, which increased as the irradiation dose increased. The second-derivative of these spectra, allow the conformationally sensitive membrane acyl chain methylene stretching modes to be separated from the protein (mostly hemoglobin) vibrations that dominate the spectra of intact cells. The 2850 cm-1 band showed changes in the band shape and position after exposure to 50 and 100 Gy. Therefore it can be concluded that the band at 2850 cm-1 only is useful in monitoring the radiation effect of the lipids cell membrane intact cells.

Selim, Nabila S.; Desouky, Omar S.; Ismail, Nagla M.; Dakrory, Amira Z.

2011-12-01

24

EOS Family: A Spectroscopic Study  

NASA Astrophysics Data System (ADS)

The Eos family detected by Hirayama in 1918 has been always considered to be compositionally homogeneous. To investigate the composition and the homogeneity of the members of this family, we started a spectroscopic survey at the European Southern Observatory (ESO) with wavelength coverage ranging from 4800 to 9200 Å. We observed 45 Eos asteroid members, which constitutes the first large survey of this family. Our results reveal the Eos objects have spectral signature characterizing the whole family: a maximum at ? ˜ 8000-8500 Å and a reflectivity gradient spanning a continuous range. Only two of the 45 investigated objects seem to be interlopers. While the lower range of this spectral distribution has been easily connected with CO-CV chondrites, we have found no satisfactory meteorite counterpart to the upper range. We have interpreted the spread out of Eos spectra to be the results of compositional variation among the Eos members, implying that the Eos parent body was partially differentiated. Moreover, a space weathering effect has been proven to be present, but with a minor role played in the diversity of Eos family, the major role being the compositional variation.

Doressoundiram, A.; Barucci, M. A.; Fulchignoni, M.; Florczak, M.

1998-01-01

25

Spectroscopic Study of Sulfates Applied to Mars  

NASA Astrophysics Data System (ADS)

Definitive evidence for sulfates on Mars has been presented in 2004, including the Mars Exploration Rover Moessbauer spectroscopic identification of jarosite in Meridiani Planum and the Mars Express OMEGA visible/near infrared spectroscopic identification of kieserite in Valles Marineris and elsewhere. In addition to Moessbauer and VIS/NIR, other spectroscopic techniques can be employed for determining which sulfate minerals are present on Mars. This study focuses on the use of the thermal infrared range of the electromagnetic spectrum and the study of sulfates using emission spectroscopy to uniquely identify sulfate minerals. The fundamental molecular vibrational modes of sulfates are present in thermal infrared spectra. These modes influence the overtones and combination bands seen in VIS/NIR data. Clearly sulfate minerals are important Martian geologic materials and, because sulfates form under diverse environmental conditions, can help understand the specific formational and chemical settings that once existed on Mars.

Lane, M. D.

2004-12-01

26

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

27

Spectroscopic study of Mentha oils  

NASA Astrophysics Data System (ADS)

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

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

28

Spectroscopic studies of the transplutonium elements  

SciTech Connect

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

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

1983-01-01

29

Spectroscopic study of carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

Curran, Seamus; Weldon, D. N.; Blau, Werner; Zandbergen, Henny W.; Kastner, J.; Kuzmany, H.

1994-11-01

30

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

31

Automated heuristic analysis of spectroscopic data  

Microsoft Academic Search

Spectroscopic data consists of a set of numbers which may be plotted on a graph. These numbers indicate a range of values rather than a single discrete value. It is straightforward to assign a meaning to a single value, but interpreting the meaning of a range of values requires more judgment. In nuclear physics, spectroscopic data is related to the

Hank Simon

1988-01-01

32

Spectroscopic analysis of immobilised redox enzymes under direct electrochemical control.  

PubMed

This article reviews recent developments in spectroscopic analysis of electrode-immobilised enzymes under direct, unmediated electrochemical control. These methods unite the suite of spectroscopic methods available for characterisation of structural, electronic and coordination changes in proteins with the exquisite control over complex redox enzymes that can be achieved in protein film electrochemistry in which immobilised protein molecules exchange electrons directly with an electrode. This combination is particularly powerful in studies of highly active enzymes where redox states can be controlled even under fast electrocatalytic turnover. We examine examples in which UV-visible, IR, Raman and MCD spectroscopy have been combined with direct electrochemistry to probe redox-dependent chemistry, and consider future opportunities for 'direct' spectroelectrochemistry of immobilised enzymes. PMID:22057715

Ash, Philip A; Vincent, Kylie A

2011-11-07

33

Preliminary study on the quick detection of Acquired Immune Deficiency Syndrome by saliva analysis using surface enhanced Raman spectroscopic technique.  

PubMed

45 saliva samples of AIDS patients and 55 saliva samples in normal population were detected by the Surface-enhanced Raman spectroscopy (SERS) system. And the spectrum data were analyzed using the Support Vector Machine (SVM) algorithm, one of the data mining technologies. Statistical analysis showed that two groups were distinguished effectively. This study provided a new research direction of the quick non-invasive testing for AIDS. PMID:19963981

Yan, Wang; Lin, Hua; Jinghua, Liu; Dian, Qu; Anyu, Chen; Yi, Jiao; Xun, Guo; Chunwei, Liu; Wen, Huang; Hong, Wang

2009-01-01

34

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

2012-07-31

35

Spectroscopic generalized ellipsometry based on fourier analysis.  

PubMed

The extension of a spectroscopic ellipsometer that consists of a fixed polarizer, a rotating polarizer, a sample, and a fixed analyzer (PRPSE) to generalized ellipsometry to determining the generalized ellipsometric angles and the optical functions of an anisotropic medium is reported. The PRPSE configuration eliminates the polarization sensitivity of the light source. A general numerical technique has been derived to characterize the optical properties of the anisotropic material without intermediate generalized ellipsometric angles. The proposed method is experimentally verified for uniaxial mercuric iodide. The ordinary and the extraordinary refractive and absorption indices, respectively, N(o) = n(o)--ik(o) and N(e) = n(e)--ik(e), can be extracted directly from the Fourier coefficients measured by the PRPSE on a HgI(2) crystal face that contains the optical axis. The orientations of the optical axis with respect to the plane of incidence were also determined by direct analysis of the measured Fourier coefficients. Measurements were made of reflection across a spectral range of 1.5-4.13 eV at one angle of incidence (Phi = 70 degrees ) for several azimuths phi of the optical axis with respect to the plane of incidence. The generalized ellipsometric angles were obtained from numerical inversion by changes of both polarizer and analyzer azimuth angles P and A. PMID:18323969

En Naciri, A; Johann, L; Kleim, R

1999-08-01

36

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

37

Quantitative analysis of electron spectroscopic imaging series  

Microsoft Academic Search

We have developed new methods to quantify the data acquired by electron spectroscopic imaging (ESI) which are based on recording series of energy filtered images across inner shell loss edges or in the low loss region. From the series of ESI images, electron energy loss (EEL) spectra can be extracted for any given image area, i.e. each individual pixel or

J Mayer; U Eigenthaler; J. M Plitzko; F Dettenwanger

1997-01-01

38

Analysis of cancer tissues by means of spectroscopic methods  

PubMed Central

The personalized approach in cancer treatment stimulates the search for new analytical techniques, including spectroscopic methods such as Raman spectroscopy, mass spectrometry MALDI (matrix-assisted laser desorption/ionization) imaging and high-resolution magic angle spinning nuclear magnetic resonance (HR MAS NMR). The purpose of these studies is determination of metabolic profiles of cancer tissues, and their application in diagnostics and therapy of cancers. The review is mainly focused on application of HR MAS NMR technique. Qualitative and quantitative analysis of metabolites by means of this method is described for breast cancer tissues. In the near future HR MAS NMR in vitro studies of metabolic profiles combined with in vivo studies using MRI scanners may be applied as a new diagnostic tool.

Pacholczyk, Barbara; Fabianska, Anna; Kusinska, Renata; Potemski, Piotr; Kordek, Radzislaw

2012-01-01

39

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.

Forseth, Ry R.; Schroeder, Frank C.

2010-01-01

40

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

41

Spectroscopic studies of detonating heterogeneous explosives. [HNS  

SciTech Connect

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

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

1985-01-01

42

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

43

Laser Spectroscopic Studies of Samarium Monoxide  

NASA Astrophysics Data System (ADS)

The results of various laser spectroscopic experiments using Resolved Fluorescence Spectra (RFS), high resolution Wavelength Selected Excitation Spectroscopy (WSES), intermodulated fluorescence, and sub-Doppler Zeeman spectroscopy have been combined to investigate the structure and properties of the low-lying electronic states of samarium monoxide (SmO) in this research. Fifteen low-lying electronic states have been observed and linked together in a single energy diagram. Conclusive Omega assignments have been determined for those states. A detailed examination of the ground state shows that it is an Omega = 0 state (X0^{-}). The order and energies of the observed low-lying states are shown to be in fair agreement with those calculated from a detailed ligand field fit to the Sm^{2+ } (4f^5(^6H)6s) O^{2-} supermultiplet. Twelve of the observed low-lying states have been excited through more than twenty high resolution electronic transitions which have been rotationally analyzed. Global fits to all the transitions for the two most abundant isotopes (^{154}SmO, ^ {152}SmO) and some transitions for the four lighter isotopes (^{150} SmO, ^{149}SmO, ^{148}SmO, ^ {147}SmO) have yielded electronic term energies, rotational constants, and Omega doubling parameters for twelve low-lying and seven upper states. This is the first systematic rotational analysis for the SmO molecule. Several perturbations have been assigned and analyzed. The local perturbations have been frequently used to confirm the assignment of the spectra. Perturbation mechanisms have been proposed and the matrix elements have been calculated from the experimental results. The intensity distribution of the main and extra lines seems to support the proposed mechanisms. The Omega doubling constants and the Lande g_{rm e} factor in Zeeman spectra are obtained from the experiment and used to test the eigenfunctions of the ligand field Hamiltonian. The observed Omega doubling constants show a very good agreement with those calculated from the predicted eigenfunctions for the first few low-lying states but point to a need for revision of the eigenfunctions for higher states. The g_ {rm e} factor of (1)1 state measured from Zeeman experiment agreed with the calculated one and proved to be very sensitive to small perturbations. For the (1)2 state, the g_{rm e} factor indicates a need to modify the eigenfunctions.

Guo, Bujin

44

Clarification of EDM Phenomena by Spectroscopic Analysis  

NASA Astrophysics Data System (ADS)

In electrical discharge machining (EDM), workpiece is machined using heat of the arc-plasma generated in the discharge gap after dielectric breakdown. The characteristics and behavior of the arc-plasma during a single discharge have a great influence on the formation of the discharge crater. In order to improve the machining accuracy and surface roughness of the workpiece, it is quite necessary to research on plasma behavior and its characteristics. In this study, light intensities radiated from the plasma which are considered to reflect the material removal behavior were measured using a spectrometer under different machining conditions. It was found that the starting moment when light intensity was detected had a time delay after the dielectric breakdown. It is because of the time needed for the material to be evaporated before its temperature reaches the boiling point. Besides, the time delay increases accordingly by slowing down the rise speed of the discharge current because of lower heat flux flowing into the surface of the workpiece. In addition, heat conduction analysis was conducted to compare the time delay calculated with the experimental ones. It was found that plasma expanded in a rapid speed within about 180ns right after dielectric breakdown and remained constant with the diameter of about 20µm after that under a roughing condition of micro EDM.

Qu, Chao; Natsu, Wataru; Kunieda, Masanori

45

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

46

Photoelectron spectroscopic study of the oxyallyl diradical.  

PubMed

The photoelectron spectrum of the oxyallyl (OXA) radical anion has been measured. The radical anion has been generated in the reaction of the atomic oxygen radical anion (O(•-)) with acetone. Three low-lying electronic states of OXA have been observed in the spectrum. Electronic structure calculations have been performed for the triplet states ((3)B(2) and (3)B(1)) of OXA and the ground doublet state ((2)A(2)) of the radical anion using density functional theory (DFT). Spectral simulations have been carried out for the triplet states based on the results of the DFT calculations. The simulation identifies a vibrational progression of the CCC bending mode of the (3)B(2) state of OXA in the lower electron binding energy (eBE) portion of the spectrum. On top of the (3)B(2) feature, however, the experimental spectrum exhibits additional photoelectron peaks whose angular distribution is distinct from that for the vibronic peaks of the (3)B(2) state. Complete active space self-consistent field (CASSCF) method and second-order perturbation theory based on the CASSCF wave function (CASPT2) have been employed to study the lowest singlet state ((1)A(1)) of OXA. The simulation based on the results of these electronic structure calculations establishes that the overlapping peaks represent the vibrational ground level of the (1)A(1) state and its vibrational progression of the CO stretching mode. The (1)A(1) state is the lowest electronic state of OXA, and the electron affinity (EA) of OXA is 1.940 ± 0.010 eV. The (3)B(2) state is the first excited state with an electronic term energy of 55 ± 2 meV. The widths of the vibronic peaks of the X? (1)A(1) state are much broader than those of the a? (3)B(2) state, implying that the (1)A(1) state is indeed a transition state. The CASSCF and CASPT2 calculations suggest that the (1)A(1) state is at a potential maximum along the nuclear coordinate representing disrotatory motion of the two methylene groups, which leads to three-membered-ring formation, i.e., cyclopropanone. The simulation of b? (3)B(1) OXA reproduces the higher eBE portion of the spectrum very well. The term energy of the (3)B(1) state is 0.883 ± 0.012 eV. Photoelectron spectroscopic measurements have also been conducted for the other ion products of the O(•-) reaction with acetone. The photoelectron imaging spectrum of the acetylcarbene (AC) radical anion exhibits a broad, structureless feature, which is assigned to the X? (3)A'' state of AC. The ground ((2)A'') and first excited ((2)A') states of the 1-methylvinoxy (1-MVO) radical have been observed in the photoelectron spectrum of the 1-MVO ion, and their vibronic structure has been analyzed. PMID:21323385

Ichino, Takatoshi; Villano, Stephanie M; Gianola, Adam J; Goebbert, Daniel J; Velarde, Luis; Sanov, Andrei; Blanksby, Stephen J; Zhou, Xin; Hrovat, David A; Borden, Weston Thatcher; Lineberger, W Carl

2011-02-16

47

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

48

Spectroscopic analysis of Er 3+ transitions in lithium niobate  

Microsoft Academic Search

We report on the results of a spectroscopic analysis of the transition strengths of Er-doped LiNbO3. The line strengths of several transitions from the ground state to excited state manifolds are evaluated from measured polarised absorption spectra and analysed using Judd-Ofelt theory, taking into account the crystal anisotropy. The measured and calculated oscillator strengths at 300 K compare favourably within

J. Amin; B Dussardier; T Schweizer; M Hempstead

1996-01-01

49

A detailed spectroscopic study of an Italian fresco  

SciTech Connect

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

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

2005-02-15

50

jSIPRO - Analysis tool for magnetic resonance spectroscopic imaging.  

PubMed

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

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

2013-07-17

51

[Chemiluminescence spectroscopic analysis of homogeneous charge compression ignition combustion processes].  

PubMed

To study the combustion reaction kinetics of homogeneous charge compression ignition (HCCI) under different port injection strategies and intake temperature conditions, the tests were carried out on a modified single-cylinder optical engine using chemiluminescence spectroscopic analysis. The experimental conditions are keeping the fuel mass constant; fueling the n-heptane; controlling speed at 600 r x min(-1) and inlet pressure at 0.1 MPa; controlling inlet temperature at 95 degrees C and 125 degrees C, respectively. The results of chemiluminescence spectrum show that the chemiluminescence is quite faint during low temperature heat release (LTHR), and these bands spectrum originates from formaldehyde (CH2O) chemiluminescence. During the phase of later LTHR-negative temperature coefficient (NTC)-early high temperature heat release (HTHR), these bands spectrum also originates from formaldehyde (CH2O) chemiluminescence. The CO--O* continuum is strong during HTHR, and radicals such as OH, HCO, CH and CH2O appear superimposed on this CO--O* continuum. After the HTHR, the chemiluminescence intensity is quite faint. In comparison to the start of injection (SOI) of -30 degrees ATDC, the chemiluminescence intensity is higher under the SOI = -300 degrees ATDC condition due to the more intense emissions of CO--O* continuum. And more radicals of HCO and OH are formed, which also indicates a more intense combustion reaction. Similarly, more intense CO--O* continuum and more radicals of HCO and OH are emitted under higher intake temperature case. PMID:21137383

Liu, Hai-feng; Yao, Ming-fa; Jin, Chao; Zhang, Peng; Li, Zhe-ming; Zheng, Zun-qing

2010-10-01

52

Nonplanar property study of antifungal agent tolnaftate-spectroscopic approach  

NASA Astrophysics Data System (ADS)

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.

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

2011-09-01

53

EEL spectroscopic tomography: towards a new dimension in nanomaterials analysis.  

PubMed

Electron tomography is a widely spread technique for recovering the three dimensional (3D) shape of nanostructured materials. Using a spectroscopic signal to achieve a reconstruction adds a fourth chemical dimension to the 3D structure. Up to date, energy filtering of the images in the transmission electron microscope (EFTEM) is the usual spectroscopic method even if most of the information in the spectrum is lost. Unlike EFTEM tomography, the use of electron energy-loss spectroscopy (EELS) spectrum images (SI) for tomographic reconstruction retains all chemical information, and the possibilities of this new approach still remain to be fully exploited. In this article we prove the feasibility of EEL spectroscopic tomography at low voltages (80 kV) and short acquisition times from data acquired using an aberration corrected instrument and data treatment by Multivariate Analysis (MVA), applied to Fe(x)Co((3-x))O(4)@Co(3)O(4) mesoporous materials. This approach provides a new scope into materials; the recovery of full EELS signal in 3D. PMID:22974761

Yedra, Lluís; Eljarrat, Alberto; Arenal, Raúl; Pellicer, Eva; Cabo, Moisés; López-Ortega, Alberto; Estrader, Marta; Sort, Jordi; Baró, Maria Dolors; Estradé, Sònia; Peiró, Francesca

2012-07-24

54

A Spectroscopic Study of Field and Runaway OB Stars  

NASA Astrophysics Data System (ADS)

Identifying binaries among runaway O- and B-type stars offers valuable insight into the evolution of open clusters and close binary stars. Here we present a spectroscopic investigation of 12 known or suspected binaries among field and runaway OB stars. We find new orbital solutions for five single-lined spectroscopic binaries (HD 1976, HD 14633, HD 15137, HD 37737, and HD 52533), and we classify two stars thought to be binaries (HD 30614 and HD 188001) as single stars. In addition, we reinvestigate their runaway status using our new radial velocity data with the UCAC2 proper-motion catalogs. Seven stars in our study appear to have been ejected from their birthplaces, and at least three of these runaways are spectroscopic binaries and are of great interest for future study.

McSwain, M. Virginia; Boyajian, Tabetha S.; Grundstrom, Erika D.; Gies, Douglas R.

2007-01-01

55

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

56

A Spectroscopic Study of V617 Sagittarii  

NASA Astrophysics Data System (ADS)

We present the results of an analysis of time-resolved spectroscopy of V617 Sgr, the Wolf-Rayet star WR 109, in the H? and He II lambda4686 region. Radial velocity curves were obtained confirming the orbital period of 4.97 hr found from photometric observations. These curves indicate that the superior conjunction of the line-forming region occurs close to the primary eclipse. Constraints on the stellar masses in this peculiar binary are derived from the emission lines. The orbital behavior of the emission line profiles is analyzed in detail. A Doppler tomography study of the H? and He II lambda4686 lines is performed, aiming to estimate the locus of line formation in the system. The observations may suggest the presence of an optically thick wind. An extended emission region consistent with a hot spot and free-falling gas is also inferred from our analysis. The observed characteristics, such as the strong intensity of He II lambda4686 (He II/H? flux ratio ~2.9) and the presence of emission lines of highly ionized elements like N V and O VI, are not usually seen in normal cataclysmic variables and, in this respect, V617 Sgr is quite similar to the star V Sge.

Cieslinski, D.; Diaz, M. P.; Steiner, J. E.

1999-01-01

57

Use of different spectroscopic techniques in the analysis of Roman age wall paintings.  

PubMed

In this paper the analysis of samples of Roman age wall paintings coming from: Pordenone, Vicenza and Verona is carried out by using three different techniques: energy dispersive x-rays spectroscopy (EDS), x-rays fluorescence (XRF) and proton induced x-rays emission (PIXE). The features of the three spectroscopic techniques in the analysis of samples of archaeological interest are discussed. The studied pigments were: cinnabar, yellow ochre, green earth, Egyptian blue and carbon black. PMID:17822258

Agnoli, Francesca; Calliari, Irene; Mazzocchin, Gian-Antonio

58

Crystal growth, structural and spectroscopic analysis of hypoxanthinium chloride monohydrate  

NASA Astrophysics Data System (ADS)

Protonated form of hypoxanthinium chloride monohydrate single crystal has been grown from dilute hydrochloric acid. Single crystal X-ray analysis was carried out and the titled crystal belong to the monoclinic P2 1/ c space group. Hypoxanthine is protonated at N(1) with the hypoxanthine cations, linked to chlorine anion via weak bifurcated N-H⋯Cl hydrogen bonds and interconnected by hydrogen bonding contacts of the type N-H⋯O. Infrared, Raman and UV spectroscopic tools were applied to characterize hypoxanthinium chloride monohydrate. By applying group theoretical methods the internal and external modes of vibrations of the title crystal have been identified and discussed.

Kalyanaraman, S.; Krishnakumar, V.; Ganesan, K.

2007-07-01

59

Developments of the selective photoionization spectroscopic technique - Atomic spectroscopic studies on the density and velocity distributions of atomic beams.  

National Technical Information Service (NTIS)

In developing the materials for atomic energy, it is important to know the density -and velocity -distributions of atomic vapor beams from these materials for their spectroscopic studies. In this study, we developed an atomic beam system and completed des...

H. Cho B. H. Boo S. H. Lee J. H. Lee

1995-01-01

60

[FTIR spectroscopic study on carcinoma cells].  

PubMed

The aim of this research is to establish the cell basis for the carcinoma tissue diagnosis by exploring a method to obtain the FTIR (Fourier transform infrared) spectra of the cultured carcinoma cells with FTIR spectroscopy and investigating the special spectral features of the carcinoma cells compared with the carcinoma tissues. In the present paper, the gastric carcinoma tissues confirmed by histology were measured using a Nicolet Magna750-II FTIR spectrometer and the corresponding FTIR spectra were obtained. The cultured gastric carcinoma cells (SGC7901) were centrifuged to provide a small pellet of cells for FTIR analysis. The cell pellet was then placed on a specially designed salt plate made of BaF2. Then the infrared spectra were recorded by the same equipment. Based on the previously established criteria, a comparative study was subsequently carried out between the spectra of the cultured carcinoma cells (SGC7901) and that of the corresponding gastric tissues. Several infrared spectral features of the carcinoma cells were obtained: the different bands between cells and tissues locate in the range of 3 000-3 600 cm(-1) and 1 640 cm(-1) which are the range of the hydroxy stretching and blending bands of H2O. There are more H2O out of carcinoma cells in carcinoma tissues, so the strong bands of H2O cover the distinctive bands of carcinoma cells in carcinoma tissues. Although the carcinoma tissue is more complicated, which might originate from the intrinsic complexity of the tissue, the results suggest that the spectral features of the carcinoma cells can be well reflected by that of the carcinoma tissue. This study shows that the diagnosis of carcinoma tissue by FTIR method exhibits sufficient cell basis. PMID:18422118

Du, Jun-Kai; Shi, Jing-Sen; Xu, Yi-Zhuang; Zhang, Yuan-Fu; Sun, Xue-Jun; Wang, Jian-Sheng; Weng, Shi-Fu; Wu, Jin-Guang

2008-01-01

61

Infrared Spectroscopic Studies of the Jovian Ionsophere and Aurorae  

NASA Astrophysics Data System (ADS)

We review recent spectroscopic studies of the ionosphere of Jupiter. These demonstrate the importance of the H3+ molecular ion in understanding not only the ion-molecule chemistry of the jovian upper atmosphere, but of its energetics and dynamics as well. Comparisons are made with a new three-dimensional, global circulation model of Jupiter's ionosphere and thermosphere, JIM.

Miller, S.; Rego, D.; Achilleos, N.; Stallard, T. S.; Prangé, R.; Dougherty, M.; Joseph, R. D.; Tennyson, J.; Aylward, A.; Meuller-Wodarg, I.; Rees, D.

62

Spectroscopic studies on binding of shikonin to human serum albumin  

Microsoft Academic Search

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

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

2005-01-01

63

Halo Nucleus 11Be: A Spectroscopic Study via Neutron Transfer  

SciTech Connect

The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct-reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus 11Be, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the 10Be d;p reaction has been used in inverse kinematics at four beam energies to study the structure of 11Be. The spectroscopic factors extracted using the adiabatic model were found to be consistent across the four measurements and were largely insensitive to the optical potential used. The extracted spectroscopic factor for a neutron in an n j 2s1=2 state coupled to the ground state of 10Be is 0.71(5). For the first excited state at 0.32 MeV, a spectroscopic factor of 0.62(4) is found for the halo neutron in a 1p1=2 state.

Schmitt, Kyle [University of Tennessee, Knoxville (UTK); Jones, K. L. [University of Tennessee, Knoxville (UTK); Bey, A. [University of Tennessee, Knoxville (UTK); Ahn, S.H. [University of Tennessee, Knoxville (UTK); Bardayan, Daniel W [ORNL; Blackmon, Jeffery C [Louisiana State University; Brown, S. [University of Surrey, UK; Chae, Kyung Yuk [ORNL; Chipps, K. [Colorado School of Mines, Golden; Cizewski, J. A. [Rutgers University; Kozub, R. L. [Tennessee Technological University; Liang, J Felix [ORNL; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Matos, M. [Louisiana State University; Moazen, Brian H [ORNL; Nesaraja, Caroline D [ORNL; Nunes, F. M. [Michigan State University, East Lansing; O'Malley, Patrick [Rutgers University; Pain, Steven D [ORNL; Peters, W. A. [Rutgers University; Pittman, S. T. [University of Tennessee, Knoxville (UTK); Wilson, G. [University of Surrey, UK

2012-01-01

64

Halo nucleus 11Be: a spectroscopic study via neutron transfer.  

PubMed

The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct-reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus 11Be, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the 10Be(d,?p) reaction has been used in inverse kinematics at four beam energies to study the structure of 11Be. The spectroscopic factors extracted using the adiabatic model were found to be consistent across the four measurements and were largely insensitive to the optical potential used. The extracted spectroscopic factor for a neutron in an n?j=2s(1/2) state coupled to the ground state of 10Be is 0.71(5). For the first excited state at 0.32 MeV, a spectroscopic factor of 0.62(4) is found for the halo neutron in a 1p(1/2) state. PMID:23003029

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

2012-05-08

65

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

66

IR spectroscopic analysis of the new organic silver complex C13H13N4OAg.  

PubMed

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. PMID:23659908

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

2013-03-29

67

Spectroscopic study of bio-functionalized nanodiamonds  

Microsoft Academic Search

Nano-scale materials with attached biomolecules on the surface can be used as bioprobes in cell and tissue analysis. The conjugation of these nanoparticles with biomolecules is one of the key steps in the development of bioprobes. In this work nanometer-sized diamonds (5 and 100 nm) are functionalized and conjugated with protein lysozyme via physical adsorption. The process of creating functional

P.-H. Chung; E. Perevedentseva; J.-S. Tu; C. C. Chang; C.-L. Cheng

2006-01-01

68

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

2008-04-30

69

Spectroscopic study of coal structure and reactivity  

SciTech Connect

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

Rabenstein, D.L.

1990-09-07

70

Imaging spectroscopic analysis at the Advanced Light Source  

SciTech Connect

One of the major advances at the high brightness third generation synchrotrons is the dramatic improvement of imaging capability. There is a large multi-disciplinary effort underway at the ALS to develop imaging X-ray, UV and Infra-red spectroscopic analysis on a spatial scale from. a few microns to 10nm. These developments make use of light that varies in energy from 6meV to 15KeV. Imaging and spectroscopy are finding applications in surface science, bulk materials analysis, semiconductor structures, particulate contaminants, magnetic thin films, biology and environmental science. This article is an overview and status report from the developers of some of these techniques at the ALS. The following table lists all the currently available microscopes at the. ALS. This article will describe some of the microscopes and some of the early applications.

MacDowell, A. A.; Warwick, T.; Anders, S.; Lamble, G.M.; Martin, M.C.; McKinney, W.R.; Padmore, H.A.

1999-05-12

71

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

72

Multiband Photometric and Spectroscopic Analysis of HV Cnc  

NASA Astrophysics Data System (ADS)

In this paper, radial velocity and VI- and JHKS - (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 JHKS 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 ?, 0.52 M ?, 1.87 R ?, and 0.48 R ?, respectively. All results are compared with previously published literature values and discussed.

Gökay, G.; Gürol, B.; Derman, E.

2013-11-01

73

Spectroscopic ellipsometry study of ion-implanted Si(100) wafers  

NASA Astrophysics Data System (ADS)

Optical properties of P+ ion-implanted Si(100) wafers have been studied using spectroscopic ellipsometry (SE). The P+ ions are implanted at 150 keV with fluences ranging from 1×1014 to 2×1015 cm-2 at room temperature. An effective-medium-approximation analysis suggests that the ion-implanted layer can be explained by a physical mixture of microcrystalline and amorphous silicon. The ?(E) spectrum of the microcrystalline component is found to differ appreciably from that of single-crystalline silicon, especially in the vicinity of the sharp critical-point features. This difference in ?(E) can be successfully interpreted by increasing the broadening parameter at each critical point. Considering these and previous data, we obtain an expression, A=(5.13×1011/EacM)1.872, which enables us to estimate the amorphization-threshold fluence A for silicon implanted with optional ion species of mass number M at energy Eac in keV. No clear change in the original structure of silicon surface after P+ ion implantation has been observed by atomic force microscopy. SE has been proven to be an easy, fast, and nondestructive technique which can be used to assess important ion-implantation parameters.

Tsunoda, Kazuaki; Adachi, Sadao; Takahashi, Mitsutoshi

2002-03-01

74

Raman spectroscopic studies of the cure of dicyclopentadiene (DCPD).  

PubMed

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. PMID:16165036

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

2004-12-13

75

A spectroscopic study of the hybrid pulsator Gamma Pegasi  

NASA Astrophysics Data System (ADS)

The recent detection of both pressure and high-order gravity modes in the classical B-type pulsator Gamma Pegasi offers promising prospects for probing its internal structure through seismic studies. To aid further modelling of this star, we present the results of a detailed NLTE abundance analysis based on a large number of time-resolved, high-quality spectra. A chemical composition typical of nearby B-type stars is found. The hybrid nature of this star is consistent with its location in the overlapping region of the instability strips for ? Cephei and slowly pulsating B stars computed using OP opacity tables, although OPAL calculations may also be compatible with the observations once the uncertainties in the stellar parameters and the current limitations of the stability calculations are taken into account. The two known frequencies f1 = 6.58974 and f2 = 0.68241 c/d are detected in the spectroscopic time series. A mode identification is attempted for the low-frequency signal, which can be associated to a high-order g -mode. Finally, we re-assess the binary status of Gamma Peg and find no evidence for variations that can be ascribed to orbital motion, contrary to previous claims in the literature.

Pandey, C. P.; Morel, T.; Briquet, M.; Jayakumar, K.; Bisht, S.; Sanwal, B. B.

2011-02-01

76

Spectroscopic studies of initiation and detonation chemistry  

SciTech Connect

There is much effort currently directed towards elucidating important microscopic processes in reacting high explosives (HEs). In particular, identification of early chemical steps in initiation is crucial to a better understanding of explosive sensitivity and vulnerability. The intimate coupling of the chemical work required to sustain detonation with the mechanical properties of the material and the resulting wave motion drives experimental studies to focus on realistic cases of initiation and steady-state detonation. Extrapolation of results from more homogeneous pressure and temperature domains may provide an inadequate description of the physics and chemistry involved. In practice the study of molecular properties in the extreme environment of detonation requires fast detection of transient phenomena. Over the past few years, the investigators have applied various optical techniques to studies of molecular mechanisms of initiation and detonation. The main focus has been to study reactions in compressed granular HEs like those commonly used in weapon components. Four experimental techniques were used: emission spectroscopy; fast-framing photography; time-resolved infrared spectral photography (TRISP); and single-pulse Raman spectroscopy. In this paper the investigators describe; (1) use of fast-framing photography and emission spectroscopy to study spatial and temporal character of emitted light from detonating HEs; (2) use of TRISP technique to monitor formation of water from various detonating HEs; and (3) use of single-pulse Raman scattering to study changes in shocked TATB. 11 refs., 5 figs.

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

1987-01-01

77

Photoluminescence and vibrational spectroscopic studies on weathered uranium oxides  

NASA Astrophysics Data System (ADS)

Spectroscopic studies were performed both on uranium oxides as baseline and on uranium oxides artificially weathered under known laboratory conditions in air, varying humidity, carbon dioxide concentration, temperature and exposure to UV light. Spectroscopic techniques included photoluminescence and diffuse reflectance FTIR. Photoluminescence measurements were made using a Spex Fluorolog-3TM spectrofluorometer with phosphorimeter. FTIR measurements were made using a Bomem MB157 FTIR spectrophotometer with DTGS detector and approximately 450 cm-1 cut-off and a Graseby SelectorTM diffuse reflectance accessory with special cells and diamond dust as diluent and internal standard. Weathered-related reactions involving the uranium oxides that have been studied include oxidation and the formation of hydroxides and carbonates. Data are discussed with respect to both the reactions of the uranium oxides in the study and in context of reaction chemistry and mechanisms that have been previously documented. The results will be discussed in the context of environmental monitoring.

Eastwood, Delyle; Martin, Jeffrey B.; Burggraf, Larry W.; Rand, Dennis S.; Zickafoose, Matthew S.; Perry, Dale L.

1999-02-01

78

High-pressure spectroscopic studies on solid germane  

NASA Astrophysics Data System (ADS)

We performed extensive spectroscopic studies on dense germane up to 110 GPa. Pressure -- temperature phase diagram has been established from Raman and infrared spectra. There is no any trace of decomposition of Ge and H2 over the pressure range studied. Infrared measurements provide spectroscopic evidence of the metallization of this material at pressure around 16 GPa which is much lower than that observed in sister system - silane. Angle-dispersive powder x-ray diffraction studies reveal that only a structural transition is accompanying when germane enters its metallic state. These experimental observations are examined by ab initio calculations. The theoretical results of the electronic, lattice dynamical, and superconducting properties of metallic phase of this material are also presented.

Chen, Xiaojia; Struzhkin, Viktor V.; Liu, Zhen-Xian; Aihaiti, Muhetaer; Meng, Yue; Mao, Ho-Kwang; Hemley, Russell J.; Zhang, Chao; Zhang, Rui-Qin; Li, Yanling; Lin, Hai-Qing

2009-03-01

79

An impedance spectroscopic study of MEMS microphones  

Microsoft Academic Search

In this paper we present a study of the mechanical properties of MEMS microphones using impedance spectroscopy. An ideal microphone model was used to derive the equation of motion of the diaphragm and the electrical impedance of the microphone as a function of frequency. Both measurements and model show that the phase of the impedance is sensitive to the changes

Sung B. Lee; Peter V. Loeppert

2002-01-01

80

Fundamental spectroscopic studies of some atmospheric pollutants  

SciTech Connect

Molecular electronic transitions that lie in the vuv (vacuum ultraviolet) spectral region initiate many harmful photochemical modifications in the upper atmosphere. Consequently, investigations have focused on molecules that are primary atmospheric pollutants, but which are simple enough structurally to yield detailed photophysical information. Terminal electronic states for vuv transitions can be either valence or Rydberg and, at low enough energies, the distinction between the two becomes fuzzy. A major thrust of this program has been the classification and characterization of Rydberg transitions in an attempt to gain insight into Rydberg/valence state mixing Rydberg studies. It is concluded that in order to understand the nature of photochemical reactions of molecules in the upper atmosphere, it is necessary to understand the structure and function of high-energy molecular electronic states. It is also necessary to understand the ways in which these states interact and, thereby, facilitate energy transfer. The study of molecular Rydberg states provides information crucial to such an understanding.

Findley, G.L.; McGlynn, S.P.

1980-01-01

81

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

82

Spectroscopic study of gamma irradiated bovine hemoglobin  

NASA Astrophysics Data System (ADS)

In the present study, the effects of ionizing radiation of Cs-137 and Co-60 from 4.95 to 743.14 Gy and from 40 Gy to 300 kGy, respectively, on some bovine hemoglobin characteristics were studied. Such an effect was evaluated using electron paramagnetic resonance (EPR) spectroscopy, and infra-red (IR) spectroscopy. Bovine hemoglobin EPR spectra were recorded and analyzed before and after irradiation and changes were explained in detail. IR spectra of unirradiated and irradiated Bovine hemoglobin were recorded and analyzed also. It was found that ionizing radiation may lead to the increase of free radicals production, the decrease in ?-helices contents, which reflects the degradation of hemoglobin molecular structure, or at least its incomplete performance. Results also show that the combined application of EPR and FTIR spectroscopy is a powerful tool for determining structural modification of bovine hemoglobin samples exposed to gamma irradiation.

Maghraby, Ahmed Mohamed; Ali, Maha Anwar

2007-10-01

83

Spectroscopic Studies of Atmospheric Aerosol Chemistry  

NASA Astrophysics Data System (ADS)

Particles are ubiquitous in the troposphere and are involved in chemical and physical processes affecting the composition of the atmosphere, climate, cloud albedo and human health (Finlayson-Pitts and Pitts, 2000). Organic species, such as alcohols, carboxylic acids, ketones, aldehydes, aromatics, alkenes and alkanes, originate both from anthropogenic and natural sources and comprise a large component of atmospheric particles. Gas-phase species, such as ozone, can oxidize these organics, changing the particle's oxygen-to carbon ratio and potentially altering its hygroscopicity, viscosity, morphology and reactivity. One reaction in particular, that between ozone and oleic acid, has been the focus of several recent studies and extensively researched by Ziemann (2005). Oleic acid reacts readily with ozone and has a low vapor pressure making this reaction convenient to study in the laboratory and has become the benchmark for studying heterogeneous reactions representing the oxidative processing of atmospheric organic aerosols. A critical source of uncertainty in reactivity estimates is a lack of understanding of the mechanism through which some VOCs are oxidized. This knowledge gap is especially critical for aromatic compounds. Because the intermediate reaction steps and products of aromatics oxidation are unknown, chemical mechanisms incorporate parameters estimated from environmental chamber experiments to represent their overall contribution to ozone formation, e.g. Volkamer et al. ( 2006). Previous studies of uncertainties in incremental reactivity estimates for VOCs found that the representation of aromatics chemistry contributed significantly to the estimated 40 - 50% uncertainties in the incremental reactivities of common aromatic compounds Carter et al. (2002). This study shows development of an effective IR method that can monitor the reaction and hence obtain the kinetics of the ozonolysis of an aromatic compound in the aerosol phase. The development of such a method allowed for qualitative determination of products during ozonolysis reaction of a symmetric aromatic organic compound. The major and some of the minor products from the ozonolysis stilbene have been determined from solution- phase ozonolysis experiments. The ozonolysis of aromatic compounds has become an area of significant interest within the atmospheric community. Development of knowledge into the mechanisms and reactions that aromatic compounds undergo during ozonolysis is crucial to better understand the complexity of aromatic compounds in the atmosphere. References P. J. Zeimann, Faraday Discuss., 2005, 130, 469. Finlayson-Pitts and Pitts, Chemistry of the Upper and Lower Atmosphere.Academic Press, New York, 2000 Carter et al., 2002; The Mechanisms of Atmospheric Oxidation of Aromatic Hydrocarbons, Oxford University Press, New York, 2002, 556. Rainer Volkamer et al., Geophysical research letters., 2006, Vol 33.

Wamsley, R.; Leather, K.; Horn, A. B.; Percival, C.

2008-12-01

84

Spectroscopic study of coal structure and reactivity  

SciTech Connect

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

Rabenstein, D.L.

1990-09-07

85

Spectroscopic and quantum chemical studies of isocytosine  

SciTech Connect

The methods of electronic and vibrational (IR) spectroscopy were used to study the spectral properties of isocytosine in H/sub 2/O, D/sub 2/O, chloroform, and hexane in a wide concentration interval. Quantum chemical calculations of tautomeric forms and dimers of isocytosine were carried out. The bands of the calculated and experimental spectra were assigned. The results of the quantum calculations were compared with the experimental data. The spectral bands were classified according to the type of tautomer or dimer to which they belong.

Tulub, A.A.; Semenov, S.G.; Stetsenko, A.I.; Yudovich, E.E.

1988-07-01

86

Photoelectron Spectroscopic Study of LiH  

NASA Astrophysics Data System (ADS)

The X-ray photoelectron spectrum and the Li K photoelectric yield spectrum of LiH have been measured to study the electronic structure of the valence band and the conduction band. The structure of the spectra is compared with the existing energy-band calculations of LiH. The calculated energy band including the correlation-relaxation effects explains qualitatively the observed shapes of the spectra. However, in detail there exist several discrepancies between the experimental and the calculated results with respect to the band width and the energy differences among the core level, the valence band and the conduction band.

Ichikawa, Kouichi; Suzuki, Naoki; Tsutsumi, Kenjiro

1981-11-01

87

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

88

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

89

Spectroscopic Analysis of the Eclipsing Binary ? CrB  

NASA Astrophysics Data System (ADS)

The eclipsing binary ? CrB, is a well-known double-lined spectroscopic binary. The system is considered unique among main-sequence systems with respect to its small mass ratio and large magnitude difference between the components. Our aim in the present paper is to compute the orbital parameters and to model the atmospheric parameters of the system. Synthetic spectral analysis of both the individual and disentangled spectra has been performed and yielded effective temperatures T eff = 10000±250 K, surface gravities logg = 4±0.25 and projected rotational velocities v sini = 110±5 km/sec for the primary component, and T eff = 6000±250 K and logg = 4.5±0.25 for the secondary component. Evolutionary state of the system is investigated using stellar models.

Nouh, M. I.; Saad, S. M.; Korany, B.; Elkhamisy, M. A.

2013-09-01

90

Spectroscopic Analysis of the Eclipsing Binary ? CrB  

NASA Astrophysics Data System (ADS)

The eclipsing binary ? CrB, is a well-known double-lined spectroscopic binary. The system is considered unique among main-sequence systems with respect to its small mass ratio and large magnitude difference between the components. Our aim in the present paper is to compute the orbital parameters and to model the atmospheric parameters of the system. Synthetic spectral analysis of both the individual and disentangled spectra has been performed and yielded effective temperatures T eff = 10000±250 K, surface gravities log g = 4±0.25 and projected rotational velocities sin i = 110±5 km/sec for the primary component, and T eff = 6000±250 K and log g = 4.5±0.25 for the secondary component. Evolutionary state of the system is investigated using stellar models.

Nouh, M. I.; Saad, S. M.; Korany, B.; Elkhamisy, M. A.

2013-09-01

91

Energy upconversion and spectroscopic studies of ZBLAN:Er3+  

Microsoft Academic Search

A detailed spectroscopic investigation of ZBLAN:Er3+ sample was performed. Infrared to green, red to blue and blue to ultraviolet energy upconversion studies in this material were also performed. When the material was pumped with a 637 nm dye laser upconversion signals at 402 nm, whose efficiency is ~0.04%, were detected. Intensity parameters, transition probabilities, lifetimes and quantum efficiencies are also

S. R. Bullock; B. R. Reddy; P. Venkateswarlu; S. K. Nash-Stevenson; J. C. Fajardo

1997-01-01

92

A spectroscopic and computational study of stereochemistry in 2-hydroxymutilin  

Microsoft Academic Search

A computational and spectroscopic study of two epimers of 2-hydroxymutilin was conducted to obtain assignments for the configuration of the carbon at the 2-position. Gas-phase structural models for (R)- and (S)-2-hydroxymutilin were optimized using density functional theory (DFT). These models were validated using internuclear distances measured from 1H nuclear Overhauser effect (NOE) build-up rates in CDCl3 solution. The models were

Frederick G. Vogt; Grant P. Spoors; Qiaogong Su; Yemane W. Andemichael; Huan Wang; Thomas C. Potter; Douglas J. Minick

2006-01-01

93

Raman spectroscopic studies of Ni–W oxide thin films  

Microsoft Academic Search

We report on a Raman spectroscopic study of sputtered nickel–tungsten oxide films. Their crystallographic and chemical identification with electrochemical lithium insertion and extraction are obtained by Raman spectroscopy. The Raman spectra of as-deposited Ni–W oxide films show a strong peak at 525 cm?1 due to vibrations of the Ni?O bonds and two weaker peaks at 875 and 950 cm?1, which

Se-Hee Lee; Hyeonsik M. Cheong; Nam-Gyu Park; C. Edwin Tracy; Angelo Mascarenhas; David K. Benson; Satyen K. Deb

2001-01-01

94

Spectroscopic studies in open quantum systems  

PubMed

The Hamiltonian H of an open quantum system is non-Hermitian. Its complex eigenvalues E(R) are the poles of the S matrix and provide both the energies and widths of the states. We illustrate the interplay between Re(H) and Im(H) by means of the different interference phenomena between two neighboring resonance states. Level repulsion may occur along the real or imaginary axis (the latter is called resonance trapping). In any case, the eigenvalues of the two states avoid crossing in the complex plane. We then calculate the poles of the S matrix and the corresponding wave functions for a rectangular microwave resonator with a scatter as a function of the area of the resonator as well as of the degree of opening to a waveguide. The calculations are performed by using the method of exterior complex scaling. Re(H) and Im(H) cause changes in the structure of the wave functions which are permanent, as a rule. The resonance picture obtained from the microwave resonator shows all the characteristic features known from the study of many-body systems in spite of the absence of two-body forces. The effects arising from the interplay between resonance trapping and level repulsion along the real axis are not involved in the statistical theory (random matrix theory). PMID:11088480

Rotter; Persson; Pichugin; Seba

2000-07-01

95

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

96

Photoelectron spectroscopic studies of 5-halouracil anions  

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

97

Spectroscopic studies of cold, gas-phase biomolecular ions  

NASA Astrophysics Data System (ADS)

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

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

98

Spectroscopic studies of protein folding: Linear and nonlinear methods  

PubMed Central

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

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

2012-01-01

99

Resonance Raman spectroscopic studies of enzymesubstrate intermediates at 5 K  

NASA Astrophysics Data System (ADS)

A simple and versatile system for resonance Raman (RR) spectroscopic analysis of enzymesubstrate complexes at liquid helium temperatures is described. The system allows us to record high-quality RR spectra for dithioacyl papain intermediates (MeO-Phe-Gly- and MeO-Gly-Gly-Phe-Gly-C (S)S-papain) in ice matrices at 5 K. Based on established structure-spectra correlations, it is concluded that the active-site conformation of the intermediates about the ??, ?? glycinic linkages and cysteine-25 side chain is B-G+-PH both in ice matrices at 5 K and in solution at room temperature.

Kim, Munsok; Carey, Paul R.

1991-01-01

100

FT-IR spectroscopic study of phase transformation of chloropinnoite in boric acid solution at 303 K  

Microsoft Academic Search

The dissolution and transformation of chloropinnoite in boric acid solution at 303 K has been studied using FT-IR difference spectroscopic technique. After equilibrium was reached, liquid and solid phases were separated and FT-IR spectra of each phase were recorded, FT-IR spectroscopic analysis of solid phases indicated that the transformation products, with the increase of boron-concentration in solution, were 2MgO?·?3B2O3?·?15H2O (inderite),

Liu Zhihong; Gao Shiyang; Xia Shuping

2003-01-01

101

Continuous spectroscopic analysis of vanadous and vanadic ions  

SciTech Connect

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

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

1993-10-01

102

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

103

Thermal,spectroscopic and rheological study of mineral base lubricating oils  

Microsoft Academic Search

The thermal degradation process of mineral base lubricating oils was\\u000a studied in this work by means of thermal, spectroscopic and rheologic analysis.\\u000a The lubricating oils were degraded at temperatures varying from 150 to 210C,\\u000a and for degradation times from 1 to 48 h. After the degradation, the lubricating\\u000a oils were characterized by X-ray fluorescence, IR and NMR spectroscopies,\\u000a rheological properties

J. C. O. Santos; L. N. Lima; Iêda M. G. Santos; A. G. Souza

2007-01-01

104

Spectroscopic study of Ce and Cr-doped LiSrAlF6 crystals  

Microsoft Academic Search

Undoped, as well as Ce3+ and Cr3+ doped LiSrAlF6 (LiSAF) crystals have been examined by Raman spectroscopy in order to identify the system's molecular vibrations and the role of doping. Furthermore the electron spin resonance (ESR) spectroscopic technique has been used to study the distortions of the local crystalline environment of Ce. The analysis of the main ESR resonance shows

A. G. Kontos; G. Tsaknakis; Y. S. Raptis; A. Papayannis; E. Landulfo; S. L. Baldochi; E. Barbosa; N. D. Vieira

2003-01-01

105

A high resolution spectroscopic study of XX Ophiuchi  

NASA Astrophysics Data System (ADS)

The star XX Oph has been known to exhibit peculiar spectral variabilities since the work of Merrill in 1924. A high resolution spectroscopic study of the XX Oph spectra taken in July 1996 and later in June 1997 also exhibit distinctly different line profiles in several spectral regions, the most pronounced variations being in the sodium D and H? profiles. We have estimated the displacement velocities of the strong emission line profiles and their absorption components whenever possible and made an attempt to examine possible physical scenarios that can account for its peculiar variability.

Goswami, Aruna; Rao, N. K.; Lambert, D. L.

2001-09-01

106

Spectroscopic analysis using a hybrid LIBS-Raman system  

NASA Astrophysics Data System (ADS)

A novel setup, combining two spectroscopic techniques, laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy in a hybrid unit, is described. The work presented herein is part of a broader project that aims to demonstrate the applicability of the hybrid LIBS-Raman unit as an analytical tool for the investigation of samples and objects of cultural heritage. The system utilizes a nanosecond pulsed Nd:YAG laser (532 nm) for both LIBS and Raman analysis. In the Raman mode, a low intensity beam from the laser probes the sample surface and the scattering signal is collected into a grating spectrograph coupled to an intensified charge-coupled device (ICCD) detector, which records the Raman spectrum. In the LIBS mode a single high intensity pulse from the laser irradiates the sample surface and the time- and spectrally-resolved emission from the resulting laser ablation plume yields the LIBS spectrum. The use of a non-gated CCD detector was found to produce similar quality data (in terms of S/N ratio and fluorescence background) in the Raman mode, while in the LIBS mode spectral features were clearly broader but did not prevent identification of prominent atomic emission lines. Several model pigment samples were examined and the data obtained show the ability of the hybrid unit to record both Raman and LIBS spectra from the same point on the sample, a clear advantage over the use of different analytical setups.

Giakoumaki, A.; Osticioli, I.; Anglos, D.

2006-06-01

107

X-ray spectroscopic studies of secondary battery materials  

NASA Astrophysics Data System (ADS)

X-ray spectroscopic methods, both NEXAFS and EXAFS were used in the study of the structural and electronic properties of different types of new battery materials. NEXAFS analysis of the spectra of Lisb{1-x}CoO2 secondary battery cathodes revealed that the addition of Li proceeds is strongly correlated to the increase in electronic charge on the Co ion. A structural phase transition is confirmed for x=0.5. The presence of Mnsp{+2} is detected in the conventionally made LiMnOsb2 cathodes but not in ones prepared according to the new ADL process. Lisb{x}Vsb6Osb{13} cathode material, where 0? x?6, was measured using x-ray absorption, EPR and NMR techniques. The intercalation mechanism involves a conversion of Vsp{+5} to Vsp{+4} in Vsb6Osb{13} until the composition Lisb2Vsb6Osb{13} is reached. Further addition of lithium is accompanied by the conversion of Vsp{+4} to Vsp{+3} until Lisb8Vsb6Osb{13} is reached. The process is complicated and involves structural phase changes and increasing structural disorder within the multi-phase system as Li concentration is increased. Studies of LiNi/CoOsb2 intercalation cathodes prepared by a novel sol-gel technique suggests that although the partial substitution of Co for Ni stabilizes the system by removing Nisp{+2}, a Jahn-Teller type structural distortion in the predominantly Nisp{=3} system persists. In-situ EXAFS measurements of the pyrite cathode in a new Li/CPE/FeSsb2 showed two distinct environments of the Fe ion, which were interpreted as those of metallic Fe and residual FeSsb2 at high lithium concentration, and Lisb2FeSsb2 and residual FeSsb2 at low lithium concentration. The formation of FeS was not detected. A new type of hydrogen ion battery incorporating a MnSOsb4sp&*slash;Hsb2O based cathode and polymer electrolyte was also studied. Heavily cycled and discharged cathodes showed an almost identical Mn local structure to that of single cycled ones. The Mn environment becomes very different in the charged cathodes, due to a highly reversible chemical change. Formation of Mn+4 at the expense of Mn+3, upon charging is an unexpected result. Mn+7 does not appear to be created in this process.

Kostov, Svilen Dimitar

1998-09-01

108

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

PubMed

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

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

2013-02-21

109

A correlation of spectroscopic parameters from different magnetic resonance spectroscopies for thiazides: a study by NQR, NMR, EPR and DFT methods  

Microsoft Academic Search

A Letter is devoted to a detailed parallel analysis of the spectroscopic parameters such as quadrupole coupling constant (NQR), chemical shift, chemical shift anisotropy, asymmetry parameter (NMR) and hyperfine coupling constant (EPR) for thiazides. The compounds were studied in solid state by the resonance (NQR, NMR and EPR) and density functional theory (DFT) methods. The spectroscopic parameters determined at room

J. N. Latosi?ska

2004-01-01

110

Raman spectroscopic study of a genetically altered kidney cell  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

111

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

112

Spectroscopic studies on the oxidative decomposition of malachite green using ozone.  

PubMed

Spectroscopic studies on the oxidative decomposition of Malachite Green (MG) using ozone were investigated. Parameters such as color removal, initial dye concentration, COD reduction, reaction temperature and pH were studied to determine optimum conditions for complete MG decomposition. Complete removal of MG color was achieved within 10 min of reaction with ozone. The ozone oxidation reaction time increased as concentration of MG increases, inferring, there would be increase in MG removal as concentration decreases. COD reduction was observed as reaction time increases and the rate of reaction monotonically increased as temperature increases. From the spectroscopic analysis of the intermediates and the by-products of MG reaction with ozone, a tentative mechanistic approach of MG decomposition was postulated. It was also observed that after five minutes of ozone oxidation, color removal rate in the wastewater containing Malachite Green obtained from a small scale local dyeing industry reached almost 90%. PMID:20390910

Baek, Mi-Hwa; Ijagbemi, Christianah Olakitan; Kim, Dong-Su

2010-01-01

113

Detection and Monitoring of Neurotransmitters - a Spectroscopic Analysis  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

114

Synthesis, structural, spectroscopic studies, NBO analysis, NLO and HOMO-LUMO of 4-methyl-N-(3-nitrophenyl)benzene sulfonamide with experimental and theoretical approaches  

NASA Astrophysics Data System (ADS)

The sulfonamide compound, 4-methyl-N-(3-nitrophenyl)benzene sulfonamide (abbreviated as 4M3NPBS) has been synthesized and characterized by FTIR, FT-Raman NMR, single crystal X-ray diffraction and thermal analysis. Density functional (DFT) calculations have been carried out for the title compound by performing DFT level of theory using B3LYP/6-31G(d,p) basis set. The calculated results show that the predicted geometry can well reproduce the structural parameters. Predicted vibrational frequencies have been assigned and compared with the experimental IR spectra and they support each other. The UV-Vis spectrum of the compound was recorded. The theoretical electronic absorption spectra have been calculated by using CIS, TD-DFT, ZINDO methods. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The first order hyperpolarizability (?0) of 4M3NPBS was calculated using B3LYP/6-31G(d,p) method on the basis of finite-field approach. In addition, frontier molecular orbitals and molecular electrostatic potential were carried out by using density functional theory (DFT/B3LYP) 6-31G(d,p) basis set. The calculated HOMO and LUMO energies show that charge transfer occur in the molecule. The thermal stability of the title compound was determined with the aid of thermo gravimetric analysis (TGA) and differential thermal analysis (DTA).

Sarojini, K.; Krishnan, H.; Kanakam, Charles C.; Muthu, S.

2013-05-01

115

In vitro spectroscopic study of normal and pathological blood denaturation  

NASA Astrophysics Data System (ADS)

By means of a systematic spectroscopic study of an in vitro blood clot model, iron compounds involved in blood denaturation have been identified and evaluated at each stage of blood denaturation. So, a blood denaturation pattern is available for normal blood, but also for some pathological bloods (polyglobulic, ?-thalassemic and drepanocytic). Normal blood denaturation stands for a reference that will be used for several purposes. Thus, this study compares normal and pathological blood denaturation rates. Polyglobulic and ?-thalassemic blood denaturations are quite similar to normal blood denaturation. On the opposite, drepanocytic blood denaturation is really different (some hemochromes are not observed) and is a lot slower. This delay can be attributed to deoxyhemoglobin S fiber formation that could protect trapped compounds from oxidization.

Jumpertz, C. M.; Rimbert, J. N.

1996-12-01

116

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

NASA Astrophysics Data System (ADS)

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

Xavier, R. John; Gobinath, E.

2012-11-01

117

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

118

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

119

Spectroscopic Observations and Analysis of the Peculiar SN 1999aa.  

National Technical Information Service (NTIS)

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

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

2004-01-01

120

Molecular spectroscopic study for suggested mechanism of chrome tanned leather.  

PubMed

Collagen represents the structural protein of the extracellular matrix, which gives strength of hides and/or skin under tanning process. Chrome tan is the most important tanning agent all over the world. The methods for production of leather evolved over several centuries as art and engineering with little understanding of the underlying science. The present work is devoted to suggest the most probable mechanistic action of chrome tan on hide proteins. First the affect of Cr upon hide protein is indicated by the studied mechanical properties. Then the spectroscopic characterization of the hide protein as well as chrome tanned leather was carried out with Horizontal Attenuated Total Reflection (HATR) FT-IR. The obtained results indicate how the chromium can attached with the active sites of collagen. Molecular modeling confirms that chromium can react with amino as well as carboxylate groups. Four schemes were obtained to describe the possible interactions of chrome tan with hide proteins. PMID:22225606

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

2011-12-22

121

Spectroscopic and Electrical Conductivity Studies of Some Semicarbazide Hydrochloride Complexes  

NASA Astrophysics Data System (ADS)

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

Fadly, M.; El-Manakhly, H.

1998-11-01

122

Absorption spectroscopic studies on gamma irradiated bismuth borosilicate glasses  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

123

DFT study of conformational and spectroscopic properties of yatakemycin.  

PubMed

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

Pichierri, Fabio; Galasso, Vinicio

2007-06-12

124

Vibrational spectroscopic studies and Natural Bond Orbital analysis of 4,6-dichloro-2-(methylthio)pyrimidine based on density functional theory  

NASA Astrophysics Data System (ADS)

The FT-IR and FT-Raman spectra of 4,6-dichloro-2-(methylthio)pyrimidine (DMP) have been recorded and analyzed. The optimized geometry, intramolecular hydrogen bonding, and harmonic vibrational wave numbers of DMP have been investigated with the help of B3LYP density functional theory (DFT) method supplemented with 6-31G** basis set. The infrared and Raman spectra were predicted theoretically from the calculated intensities. Natural Bond Orbital (NBO) analysis of DMP has been performed to indicate the presence of intramolecular C-H⋯Cl hydrogen bonding. The formation of Lewis and non-Lewis orbitals and second-order perturbation energies of DMP have also been reported.

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

2011-10-01

125

Study of Non-Rigid Aromatic Molecules by Supersonic Molecular Jet Spectroscopy: Observation and Spectroscopic Analysis of the Stable Conformations of Various Alkylbenzenes.  

National Technical Information Service (NTIS)

The technique of supersonic molecular jet laser spectroscopy was used to determine the stable conformations of a series of alkylbenzenes. This study demonstrates, for the first time, the sensitivity of molecular jet spectroscopy in determining both the nu...

E. R. Bernstein H. V. Secor J. I. Seeman P. J. Breen V. H. Grassian

1988-01-01

126

Study of Non-Rigid Aromatic Molecules by Supersonic Molecular Jet Spectroscopy: Observation and Spectroscopic Analysis of the Stable Conformations of Various Alkylbenzenes.  

National Technical Information Service (NTIS)

The technique of supersonic molecular jet laser spectroscopy was used to determine the stable conformations of a series of alkylbenzenes. This study demonstrates, for the first time, the sensitivity of molecular jet spectroscopy in determining both the nu...

E. R. Bernstein H. V. Secor J. I. Seeman P. J. Breen V. H. Grassian

1989-01-01

127

Molecular structure, spectroscopic (FT-IR, FT-Raman) studies and first-order molecular hyperpolarizabilities, HOMO-LUMO, NBO analysis of 2-hydroxy-p-toluic acid  

NASA Astrophysics Data System (ADS)

FT-Raman and FT-IR spectra for 2-hydroxy-p-toluic acid molecule had been recorded in the regions 3500-100 cm-1 and 4000-400 cm-1, respectively. Vibrational frequencies have been calculated in optimum state by employing density functional theory (DFT) and Hartree Fock (HF) methods with 6-311++G(d,p) basis set in monomeric form. SQM force fields have also been used to calculate potential energy distributions in order to make conspicuous vibrational assignments. Optimized geometries of the molecule had been interpreted and compared. The electric dipole moment and first hyperpolarizability values of the investigated molecule were computed using ab initio and DFT calculations. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond analysis. The results show that charge in electron density (ED) in the ?* antibonding orbitals and E(2) energies confirms the occurrence of ICT within the molecule.

Balachandran, V.; Nataraj, A.; Karthick, T.

2013-03-01

128

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

NASA Astrophysics Data System (ADS)

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 1H and 13C 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.

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

2013-10-01

129

On the Mechanism of Ion Transport through Polyphosphazene Solid Polymer Electrolytes 1: NMR, IR, and Raman Spectroscopic Studies and Computational Analysis of 15N Labeled Polyphosphazenes  

SciTech Connect

Comprehensive investigation of lithium ion complexation with 15N-labeled polyphosphazenes- 15N-poly[bis(2-(2-methoxyethoxy)ethoxy)phosphazene] (15N-MEEP) and 15N-poly-[((2-allylphenoxy)0.12(4-methoxyphenoxy)1.02(2-(2-methoxyethoxy)ethoxy)0.86)phosphazene] (15N-HPP)-was performed by NMR, IR, and Raman spectroscopies. Previous studies characterized the ionic transport through the polymer matrix in terms of "jumps" between neighboring polymer strands utilizing the electron lone pairs of the etherial oxygen nuclei with the nitrogen nuclei on the polyphosphazene backbone not involved. However, noteworthy changes were observed in the NMR, IR, and Raman spectra with the addition of lithium trifluoromethanesulfonate (LiOTf) to the polyphosphazenes. The data indicate that the preferred association for the lithium ion with the polymer is with the nitrogen nuclei, resulting in the formation of a "pocket" with the pendant groups folding around the backbone. NMR temperature-dependent spin-lattice relaxation (T1) studies (13C, 31P, and 15N) indicate significant lithium ion interaction with the backbone nitrogen nuclei. These studies are in agreement with molecular dynamics simulations investigating lithium ion movement within the polyphosphazene matrix.

Luther, Thomas Alan; Stewart, Frederick Forrest; Budzien, Joanne Louise; Laviolette, Randall Alexander; Bauer, William Francis; Harrup, Mason Kurt; Allen, Charles Anthony; Elayan, A.

2003-03-01

130

Spectroscopic Evaluation of Glucose Concentration in Phosphate-Buffered Saline Solution Using Principal Component Analysis  

NASA Astrophysics Data System (ADS)

Principal component analysis (PCA) has been used for quantitative analysis of infrared attenuated total reflection (ATR) spectra of chemical mixtures, so that the minute concentration of glucose in the chemical mixture would be evaluated. Spectroscopic calibration of chemical concentration has been, thus far, believed to require multidimensional least-squares methods, such as classical least squares (CLS) and partial least-squares (PLS) regression techniques. In the present study, however, the analysis of the infrared ATR spectra only by PCA has been found to be useful for the evaluation of concentration of specific minute species in a chemical mixture. The prediction accuracy by PCA only has proved to be comparable to that of PLS. The novel technique would enable us to measure the concentration of glucose in human blood with no invasion.

Nakamura, Atsushi; Hasegawa, Takeshi; Nishijo, Jujiro; Kanazawa, Masao; Aizawa, Katsuo; Sota, Takayuki

2002-04-01

131

Laser Raman spectroscopic analysis of polymorphic forms in microliter fluid volumes.  

PubMed

Knowledge and control of the polymorphic phase of chemical compounds are important aspects of drug development in the pharmaceutical industry. We report herein in situ and real-time Raman spectroscopic polymorphic analysis of optically trapped microcrystals in a microliter volume format. The system studied in particular was the recrystallization of carbamazepine (CBZ) in methanol. Raman spectrometry enabled noninvasive measurement of the amount of dissolved CBZ in a sample as well as polymorphic characterization, whereas exclusive recrystallization of either CBZ form I or CBZ form III from saturated solutions was achieved by specific selection of sample cell cooling profiles. Additionally, using a microcell versus a macroscopic volume gives the advantage of reaching equilibrium much faster while using little compound quantity. We demonstrate that laser Raman spectral polymorphic analysis in a microliter cell is a potentially viable screening platform for polymorphic analysis and could lead to a new high throughput method for polymorph screening. PMID:12486691

Anquetil, Patrick A; Brenan, Colin J H; Marcolli, Claudia; Hunter, Ian W

2003-01-01

132

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

PubMed

The usefulness of derivative spectrophotometry for simultaneous assay of l-dopa, benserazide and ascorbic acid in pharmaceuticals was studied. The parameters of derivatisation depends on composition of solution in which particular compound was determined. For quantification of l-dopa in mixtures with benserazide or ascorbic acid the first derivative was used. Its determination in ternary mixture (l-dopa+benserazide+ascorbic acid) is possible by third derivative spectra. Benserazide was assayed in presence of l-dopa using first derivative while in ternary mixture by third derivative. Direct determination of ascorbic acid is possible applying first derivative only in presence of l-dopa. The elaborated derivative spectrophotometric methods were used for assaying of l-dopa and benserazide in their commercial form "Madopar". The proposed spectrophotometric derivative method of simultaneous determination of l-dopa and benserazide was combined with FIA technique. PMID:16257716

Karpi?ska, Joanna; Smyk, Jerzy; Wo?yniec, Elzbieta

2005-11-01

133

Structural and spectroscopic studies of a model for catechol oxidase.  

PubMed

A binuclear copper complex, [Cu2(BPMP) (OAc)2][ClO4] x H2O, has been prepared using the binucleating ligand 2,6-bis[bis(pyridin-2-ylmethylamino)methyl]-4-methylphenol (H-BPMP). The X-ray crystal structure reveals the copper centers to have a five-coordinate square pyramidal geometry, with the acetate ligands bound terminally. The bridging phenolate occupies the apical position of the square-based pyramids and magnetic susceptibility, electron paramagnetic resonance (EPR) and variable-temperature variable-field magnetic circular dichroism (MCD) measurements indicate that the two centers are very weakly antiferromagnetically coupled (J = -0.6 cm(-1)). Simulation of the dipole-dipole-coupled EPR spectrum showed that in solution the Cu-O-Cu angle was increased from 126 degrees to 160 degrees and that the internuclear distance was larger than that observed crystallographically. The high-resolution spectroscopic information obtained has been correlated with a detailed ligand-field analysis to gain insight into the electronic structure of the complex. Symmetry arguments have been used to demonstrate that the sign of the MCD is characteristic of the tetragonally elongated environment. The complex also displays catecholase activity (k(cat) = 15 +/- 1.5 min(-1), K(M) = 6.4 +/- 1.8 mM), which is compared with other dicopper catechol oxidase models. PMID:18188615

Smith, Sarah J; Noble, Christopher J; Palmer, Randahl C; Hanson, Graeme R; Schenk, Gerhard; Gahan, Lawrence R; Riley, Mark J

2008-05-01

134

Electrochemical and Spectroscopic Studies of 9, 10-Anthraquinone in a Room Temperature Molten Salt.  

National Technical Information Service (NTIS)

The electrochemical and spectroscopic properties of 9,10-anthraquinone (AQ) in the low-temperature AlCl3:n-butylpyridinium chloride (BuPyCl) molten salt system have been studied as a function of melt acidity. Infrared spectroscopic data indicate that AQ e...

G. T. Cheek R. A. Osteryoung

1980-01-01

135

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

NASA Astrophysics Data System (ADS)

This paper describes thermal, physical and spectroscopic properties of glasses prepared by a novel micro wave method. These studies exhibited a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The scheme of modification of borate and vanadate groups is controlled by Sanderson's electronegativity principle. Analysis of density and glass transition temperatures suggests the presence of characteristic four coordinated borate and diboro - vanadate groups in these glasses. The presence of [BO4/2]- and [B2V2O9]2-) groups are confirmed by Infrared Spectroscopy of investigated glasses.

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

2011-07-01

136

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

PubMed

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

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

2011-07-28

137

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

1999-03-02

138

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

139

Spectroscopic study of small absorptions in optical coatings  

NASA Astrophysics Data System (ADS)

This report concerns research performed by the Utah University surface physics group for the Air Force Weapons Laboratory (AFWL), Kirtland Air Force Base, New Mexico. It is a supplement to AFWL-TR-79-197. It reports the continued study of thorium fluoride (ThF4) as an optical coating, showing that the moisture found in the ThF4 films probably originated from the preparation itself, and that ThF4 may not degrade by moisture absorption from the atmosphere as rapidly as previously thought. Further advances are reported in the characterization procedures themselves, including computer methods for data handling. New procedures were instituted for determining the optical constants of liquids. To test the procedures, the optical constants of liquid water were determined and compared with values found in literature. The procedures used are reported. A sample of Si3N4 film on germanium was analyzed spectroscopically. The dominant feature was a large infrared band revealing the presence of large amounts of silicon hydride. Finally, new procedures are reported for determining impurity concentrations in optical thin films which takes into account the local electromagnetic field strength seen by an impurity in a known optical material as matrix.

Hansen, W. N.

1982-07-01

140

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

Microsoft Academic Search

Techniques for the study of the solar corona are reviewed as an introduction to a discussion of modifications required for the study of cosmic sources. Spectroscopic analysis of individual sources and the interstellar medium is considered. The latter was studied via analysis of its effect on the spectra of selected individual sources. The effects of various characteristics of the ISM,

A. B. C. Walker Jr.

1975-01-01

141

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

142

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

143

Photoacoustic FTIR spectroscopic study of undisturbed human cortical bone.  

PubMed

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 CO 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. PMID:23257327

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

2012-11-23

144

Spectroscopic Studies of Chemical Adsorption and Reactions at Transition Metal Surfaces.  

National Technical Information Service (NTIS)

The accomplishments of the work under the title 'Spectroscopic Studies of Chemical Adsorption and Reactions at Transition Metal Surfaces' are summarized. Included are studies of flat and stepped surfaces, of surfaces with chemisorbed species and of reacti...

J. E. Demuth G. W. Rubloff

1977-01-01

145

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

146

Spectroscopic analysis of impurity precipitates in CdS films  

NASA Astrophysics Data System (ADS)

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 102 micron-scale precipitates.

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

1999-03-01

147

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

148

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

149

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...

150

Spectroscopic and electrochemical studies of horse myoglobin in dimethyl sulfoxide  

Microsoft Academic Search

This paper reports the first report of rapid, reversible direct electron transfer between a redox protein, specifically, horse myoglobin, and a solid electrode substrate in nonaqueous media and the spectroscopic (UV-vis, fluorescence, and resonance Raman) characterization of the relevant redox forms of myoglobin (Mb) in dimethyl sulfoxide (DMSO). In DMSO, the heme active site of metmyoglobin (metMb) appears to remain

Qiu Li; Patricia Mabrouk

2003-01-01

151

NEUTRON SPECTROSCOPIC STUDIES OF CAESIUM BORATE CRYSTALS AND GLASSES  

Microsoft Academic Search

The properties of alkali borate glasses are determined by the extent and detail of any molecule- like short-range order which persists in the amorphous structures. Although there is considerable evidence that these structures can contain significant proportions of superstructural units, quantitative evidence is difficult to obtain experimentally. Spectroscopic data are invaluable for testing models of glass structure and the inelastic

Roger N. Sinclair; Richard Haworth; Adrian C. Wright; G. Parkinson; Diane Holland; Jon W. Taylor; Natalia M. Vedishcheva; Irina G. Polyakova; Boris A. Shakhmatkin; Steven A. Feller; B Rijal; T Edwards

152

Raman spectroscopic and scanning electron microscopic analysis of a novel biological colonisation of volcanic rocks  

NASA Astrophysics Data System (ADS)

A novel type of colonisation of a basaltic rock, collected on the Arctic island of Svalbard, Norway, during the AMASE expedition in 2004, was characterised using Raman spectroscopy and Scanning Electron Microscopy (SEM). The sample contains two different types of extremophile communities, one occurring behind a radial white crystallisation and the other occurring inside a dark vacuole. Several types of minerals and microbial colonies have been identified by both Raman spectroscopy and SEM analyses. It is the first time that photosynthetic communities have been documented to colonise the inside of dark basaltic rocks. Our discovery has important implications for planetary exploration because it extends the analytical capability and our understanding of microbial rock colonisations to subaerial volcanic outcrops and has wide implications towards the search for life in extraterrestrial planets. In this work we also demonstrate that the use of different laser wavelengths for Raman spectroscopic studies and complementary microscopic analysis are critical for a comprehensive organic and inorganic compound identification.

Jorge Villar, Susana E.; Edwards, Howell G. M.; Benning, Liane G.

2006-09-01

153

Instrumental analysis of bacterial cells using vibrational and emission Mössbauer spectroscopic techniques  

Microsoft Academic Search

In biosciences and biotechnology, the expanding application of physicochemical approaches using modern instrumental techniques is an efficient strategy to obtain valuable and often unique information at the molecular level. In this work, we applied a combination of vibrational (Fourier transform infrared (FTIR), FT-Raman) spectroscopic techniques, useful in overall structural and compositional analysis of bacterial cells of the rhizobacterium Azospirillum brasilense,

Alexander A. Kamnev; Anna V. Tugarova; Lyudmila P. Antonyuk; Petros A. Tarantilis; Leonid A. Kulikov; Yurii D. Perfiliev; Moschos G. Polissiou; Philip H. E. Gardiner

2006-01-01

154

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.  

PubMed

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. PMID:23454843

Isac Paulraj, E; Muthu, S

2013-02-06

155

Electrochemical and Spectroscopic Studies of Some Less Stable Oxidation States of Selected Lanthanide and Actinide Elements.  

National Technical Information Service (NTIS)

Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltamm...

D. E. Hobart

1981-01-01

156

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

National Technical Information Service (NTIS)

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

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

1992-01-01

157

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

NASA Astrophysics Data System (ADS)

Water is the principal constituent of the environment for all living organisms. Nearly all biological molecules required for life are chiral. Therefore the studies of the solvation of chiral molecules in water are of fundamental importance to life science. In this work, we report ab initio and rotational spectroscopic studies of the hydrogen bonded propylene oxide (PO) -- (H2O)N =2/3 clusters, which is a continuing study from our success on PO with one water molecule in the gas phase. The sequential complexation of PO with a few water molecules is a significant step towards understanding the solvation process for this simplest cyclic ether chiral molecule. Complete geometry optimizations for the PO-water complexes are carried out at the MP2 level of theory with the 6-311++G(d,p) basis set using the GAUSSIAN03 software package. The calculated rotational constants and dipole moment components are used to aid the initial spectroscopic investigations. By systematically increasing the pressure, attachment of more water molecules to PO can be formed and distinguished from only one. Both experimental and theoretical results are used to extract structural and dynamic information about the complexes. The experimental analysis will in turn be used to judge the quality of the theoretical predictions and then determine the appropriate model for further calculations.

Su, Zheng; Xu, Yunjie

2007-06-01

158

Spectroscopic studies of uranium species for environmental decontamination applications  

NASA Astrophysics Data System (ADS)

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

Eng, Charlotte

159

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

160

Electron Spin Resonance Spectroscopic Studies of Radical Cation Reactions.  

NASA Astrophysics Data System (ADS)

A spin Hamiltonian suitable for theoretical analyses of ESR spectra in this work is derived by using the general effective Hamiltonian theory in the usual Schrodinger representation. The Permutation Indices method is extended to obtain the dynamic exchange equations used in ESR lineshape simulation. The correlation between beta-hydrogen coupling constants and their geometric orientations is derived through the use of a perturbation method. The three electron bond model is extended to rationalize unimolecular rearrangements of radical cations. The ring-closed radical cations of 9,10-octalin oxide and syn-sesquinorbornene oxide have been characterized by ESR spectroscopy in the CFCl_3 matrix at low temperature. The ESR spectra of the former radical cation exhibit a novel alternating linewidth effect arising from an internal relation between the coupling constants for the four equivalent pairs of hydrogens. The self-electron-transfer rate constants between the methyl viologen dication and cation have been determined by dynamic ESR lineshape simulations at room temperature in allyl alcohol, water, methanol and propargyl alcohol solvents. The radical cation formed by the radiolytic oxidation of allylamine in Freon matrices at 77 K is shown to be the 3-iminiopropyl distonic species(3-iminium-1-propyl radical) resulting from a symmetry-allowed 1,2-hydrogen shift in the parent radical cation. The nucleophilic endocyclization of the but-3-en-1-ol radical cation to the protonated tetrahydrofuran -3-yl radical was observed in the radiolytic oxidation of but-3-en-1-ol in Freon matrices. ESR studies of the radiolytic oxidation of 1,5-hexadiyne have resulted in the first spectroscopic characterization of the radical cation Cope rearrangement, the 1,5-hexadiyne radical cation isomerizing to the 1,2,4,5 -hexatetraene radical cation. ESR studies show that the symmetric(C_{rm 2v}) bicyclo (3.3.0) -octa-2,6-diene-4,8-diyl(a bridged 1,4 -bishomobenzene species) radical cation is produced by the radiolytic oxidation of semibullvalene in Freon matrices. The 3,4-dimethylenecyclobutene radical cation has been characterized as a ^2B_1 state by ESR spectroscopy, prepared by the radiolytic oxidation of the parent compound in Freon matrices. The ring-opening of the 3,4-dimethylenecyclobutene radical cation to the 1,2,4,5-hexatetraene radical cation was observed in the photolysis of the 3,4-dimethylenecyclobutene radical cation. The cyclooctatetraene radical cation generated by radiolytic oxidation photoisomerizes to the bicyclo (3.3.0) octa-2,6 -diene-4,8-diyl radical cation identical to the species produced directly from the radiolytic oxidation of semibullvalene. (Abstract shortened by UMI.).

Dai, Sheng

1990-01-01

161

A spectroscopic ellipsometry study of the growth and microstructure of glow-discharge amorphous and microcrystalline silicon films  

Microsoft Academic Search

Spectroscopic ellipsometry (SE) has been used to study the surface, microstructure, and optical properties of glow-discharge deposited amorphous and microcrystalline silicon films. The SE data has been analyzed using multilayer models, effective medium approximation, and linear regression analysis. The studies have shown that with increasing rf power and silane dilution, a gradual transition from good (dense) a-Si:H to a spongy

Satyendra Kumar; D. K. Pandya; K. L. Chopra

1988-01-01

162

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

163

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

NASA Astrophysics Data System (ADS)

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

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

164

Varimax extended rotation applied to multivariate spectroscopic image analysis  

Microsoft Academic Search

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

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

2004-01-01

165

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

166

Complementary phenomenological and spectroscopic studies of propane sensing with tin dioxide based sensors  

Microsoft Academic Search

Sensing of propane with SnO2-based thick film gas sensors was studied by using a combination of experimental techniques. In order to assign reaction pathways, direct IR surface spectroscopic measurements (DRIFT) were performed. For a better understanding of the full picture, the spectroscopic information was completed with catalytic conversion and electrical measurements. We observed that during propane interaction with SnO2 the

Dorota Koziej; Nicolae Bârsan; Volker Hoffmann; Jacek Szuber; Udo Weimar

2005-01-01

167

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

PubMed

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

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

2006-03-29

168

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

169

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

170

A Spectroscopic Study of the Binary delta Scuti Theta Tucanae  

NASA Astrophysics Data System (ADS)

Using high-resolution spectroscopy, the double-lined spectroscopic binary with anomalous mass-ratio of 10, and the oscillations of theta Tuc are investigated. An indication for the binarity has already been given in Paparo et al. 1996. The spectrum of the more massive component of this binary shows line-profile variations. The radial-velocity variations present some of the pulsation frequencies found in the light variations by Paparo et al. 1996. References: Paparo, M., Steken, C., Spoon, H. W. W., Birch, P. V., A&A 1996, 315, 400

De Mey, K.; Daems, K.; Sterken, C.

171

Some polyhydroxy azo–azomethine derivatives of salicylaldehyde: Synthesis, characterization, spectroscopic, molecular structure and antimicrobial activity studies  

Microsoft Academic Search

Some new substituted polyhydroxy azo–azomethine compounds were prepared by reaction of tris(hydroxymethyl)aminomethane with (E)-2-hydroxy-5-(phenyldiazenyl) benzaldehyde and its substituted derivatives. The structures of azo and azo–azomethine compounds were determined by IR, UV–vis, 1H NMR and 13C NMR spectroscopic techniques, and\\/or X-ray diffraction studies. According to IR spectra, all azo–azomethine compounds adopt keto form in solid state. UV–vis analysis has shown the

Mustafa Odabasoglu; Çigdem Albayrak; Resit Özkanca; Fatma Zehra Aykan; Peter Lonecke

2007-01-01

172

Optical properties of N+ ion-implanted and rapid thermally annealed Si(100) wafers studied by spectroscopic ellipsometry  

Microsoft Academic Search

The optical properties of N+ ion-implanted Si(100) wafers have been studied using the spectroscopic ellipsometry (SE). The N+ ions are implanted at 150 keV with fluences in the range between 1×1016 and 7.5×1016 cm-2 at room temperature. A Bruggeman effective-medium-approximation and a linear-regression analysis require a four-phase model (substrate\\/first and second damaged layers\\/ambient) to explain the experimental data of the

Katsunori Kurihara; Shin-Ichi Hikino; Sadao Adachi

2004-01-01

173

2-thiobarbituric acid test for lipid oxidation in food: Synthesis and spectroscopic study of 2-thiobarbituric acid-malonaldehyde adduct  

Microsoft Academic Search

Synthesis, purification, elemental analysis, and spectroscopic studies were undertaken to characterize the structure of the\\u000a red adduct 2:1 thiobarbituric acid (TBA)-malonaldehyde involved in the evaluation of oxidative rancidity in fats and oils.\\u000a Thin-layer chromatography, infrared and ultravioletvisible absorption, 1H (1H NMR) and 13C nuclear magnetic resonance (NMR) spectra were used. A yield of 93% was obtained in the synthesis. The

Matías Guzmán-Chozas; Isabel M. Vicario-Romero; Remedios Guillén-Sans

1998-01-01

174

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

175

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

176

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.

177

Molecular spectroscopic studies on the interaction of morin with bovine serum albumin.  

PubMed

The interaction between morin and bovine serum albumin (BSA) was studied using molecular spectroscopic approach at different temperatures under imitated physiological conditions. Quenching of intrinsic tryptophanyl fluorescence of BSA with increasing morin concentration is the actuating tool in the analysis. The obtained quenching mechanisms, binding constants, binding sites and corresponding thermodynamic parameters at different temperatures indicate that the hydrophobic interaction play a major role in the morin-BSA association. Binding affinity between morin and BSA was determined using Scatchard equation and the modified Stern-Volmer equation, and the corresponding Structure-affinity relationships of flavonoids were discussed. Site marker competitive displacement experiments demonstrated that morin binds with high affinity to site II (subdomain IIIA) of BSA. Furthermore, the circular dichroism spectral results indicated that the conformation of BSA changed in the presence of morin. In addition, the effect of some common metal ions on the binding constant between morin and BSA was examined. PMID:22564497

Hu, Yan-Jun; Yue, Hua-Li; Li, Xiao-Ling; Zhang, Si-Si; Tang, E; Zhang, Li-Ping

2012-04-19

178

Spectroscopic study of Ce- and Cr-doped LiSrAlF6 crystals  

NASA Astrophysics Data System (ADS)

Undoped, as well as Ce3+ and Cr3+ doped LiSrAlF6 (LiSAF) crystals have been examined by Raman spectroscopy in order to identify the system's molecular vibrations and the role of doping. Furthermore the electron spin resonance (ESR) spectroscopic technique has been used to study the distortions of the local crystalline environment of Ce. The analysis of the main ESR resonance shows that the Ce3+ ions substitute for Sr2+ ones in the structure and permit the description of the electronic eigenfunctions and energy splitting of its 2F5/2 ground state. We have tackled the distortion of the trigonal crystalline environment, induced by Na+ codopants acting as charge compensators to Ce3+, and we have assigned the ESR resonances to Na occupying sites at various distances from the Ce atoms. Our results indicate growth of high quality crystals.

Kontos, A. G.; Tsaknakis, G.; Raptis, Y. S.; Papayannis, A.; Landulfo, E.; Baldochi, S. L.; Barbosa, E.; Vieira, N. D.

2003-03-01

179

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...

180

Identification of primary tumors of brain metastases by infrared spectroscopic imaging and linear discriminant analysis.  

PubMed

This study applies infrared (IR) spectroscopy to distinguish normal brain tissue from brain metastases and to determine the primary tumor of four frequent brain metastases such as lung cancer, colorectal cancer, breast cancer, and renal cell carcinoma. Standard methods sometimes fail to identify the origin of brain metastases. As metastatic cells contain the molecular information of the primary tissue cells and IR spectroscopy probes the molecular fingerprint of cells, IR spectroscopy based methods constitute a new approach to determine the primary tumor of a brain metastasis. IR spectroscopic images were recorded by a FTIR spectrometer equipped with a macro sample chamber and coupled to a focal plane array detector. Unsupervised cluster analysis of IR images revealed variances within each sample and between samples of the same tissue type. Cluster averaged IR spectra of tissue classes with known diagnoses were selected to develop a metric with eight variables. These data trained a supervised classification model based on linear discriminant analysis that was used to identify the origin of 20 cryosections including one brain metastasis with an unknown primary tumor. PMID:16700626

Krafft, Christoph; Shapoval, Larysa; Sobottka, Stephan B; Schackert, Gabriele; Salzer, Reiner

2006-06-01

181

Optical spectroscopic study on magnetoelectric MnWO4  

NASA Astrophysics Data System (ADS)

We report optical spectroscopic investigation on a multiferroic oxide compound, MnWO4. This compound is known to exhibit ferroelectricity induced by the incommensurate spiral magnetic ordering in a temperature range of 7.6 K and 12.7 K [1]. We grew single crystals of MnWO4 by using the floating zone method. To examine the optical anisotropy originating from the monoclinic crystal structure, we measured reflectivity spectra of MnWO4 with light polarizations along three crystallographic axes, and calculated the optical conductivity spectra through the Kramers-Kronig transformation for each axis. We discuss the anisotropic phonon structures and electronic structures with temperature and magnetic field dependence in relation to its multiferroic properties. [1] K. Taniguchi et al., Phys. Rev. Lett. 97, 097203 (2006).

Choi, Woo Seok; Taniguchi, Kouji; Moon, Soon Jae; Kim, Sun Jung; Seo, Sung Seok A.; Lee, Yoon Sang; Arima, Taka-Hisa; Noh, Tae Won

2008-03-01

182

Spectroscopic study of carbonaceous dust particles grown in benzene plasma  

NASA Astrophysics Data System (ADS)

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

Lee, Szetsen; Chen, Hsiu-Feng; Chin, Chien-Ju

2007-06-01

183

Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements  

Microsoft Academic Search

A photometric and spectroscopic analysis of 152 cool white dwarf stars is\\u000apresented. The discovery of 7 new DA white dwarfs, 2 new DQ white dwarfs, 1 new\\u000amagnetic white dwarf, and 3 weak magnetic white dwarf candidates, is reported,\\u000aas well as 19 known or suspected double degenerates. The photometric energy\\u000adistributions, the Halpha line profiles, and the trigonometric

P. Bergeron; S. K. Leggett; Maria Teresa Ruiz

2000-01-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

186

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

187

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.

Wang, Chuji; Sahay, Peeyush

2009-01-01

188

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

189

Fourier transform infrared spectroscopic analysis of cell differentiation  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

190

Spectroscopic determination of leaf water content using continuous wavelet analysis  

Microsoft Academic Search

The gravimetric water content (GWC, %), a commonly used measure of leaf water content, describes the ratio of water to dry matter for each individual leaf. To date, the relationship between spectral reflectance and GWC in leaves is poorly understood due to the confounding effects of unpredictably varying water and dry matter ratios on spectral response. Few studies have attempted

T. Cheng; B. Rivard; A. Sánchez-Azofeifa

2011-01-01

191

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

NASA Astrophysics Data System (ADS)

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

Pearson, John Christoffersen

1995-01-01

192

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

193

Optical and EPR spectroscopic studies of demetallation of hemin by L-chain apoferritins.  

PubMed

Earlier crystallographic and spectroscopic studies had shown that horse spleen apoferritin was capable of removing the metal ion from hemin (Fe(III)-protoporphyrin IX) [G. Précigoux, J. Yariv, B. Gallois, A. Dautant, C. Courseille, B. Langlois d'Estaintot, Acta Cryst. D50 (1994) 739-743; R.R. Crichton, J.A. Soruco, F. Roland, M.A. Michaux, B. Gallois, G. Précigoux, J.-P. Mahy, D. Mansuy, Biochemistry 36 (1997) 15049-15054]. We have carried out a detailed re-analysis of this phenomenon using both horse spleen and recombinant horse L-chain apoferritins, by electron paramagnetic resonance spectroscopy (EPR) to unequivocally distinguish between heme and non-heme iron. On the basis of site-directed mutagenesis and chemical modification of carboxyl residues, our results show that the UV-visible difference spectroscopic method that was used to establish the mechanism of demetallation is not representative of hemin demetallation. EPR spectroscopy does establish, as in the initial crystallographic investigation, that hemin demetallation occurs, but it is much slower. The signal at g=4.3 corresponding to high spin non-heme-iron (III) increases while the signal at g=6 corresponding to heme-iron decreases. Demetallation by the mutant protein, while slower than the wild-type, still occurs, suggesting that the mechanism of demetallation does not only involve the cluster of four glutamate residues (Glu 53, 56, 57, 60), proposed in earlier studies. However, the mutant protein had lost its capacity to incorporate iron, as had the native protein in which the four Glu residues had been chemically modified. Interestingly, a signal at g=1.94 is also observed. This signal most likely corresponds to a mixed-valence Fe(II)-Fe(III) cluster suggesting that a redox reaction may also be involved in the mechanism of demetallation. PMID:16781777

Carette, Noëlle; Hagen, Wilfred; Bertrand, Luc; de Val, Natalia; Vertommen, Didier; Roland, Francine; Hue, Louis; Crichton, Robert R

2006-06-16

194

Monomer, clusters, liquid: an integrated spectroscopic study of methanol condensation.  

PubMed

We have combined static pressure, spectroscopic temperature, Fourier transform infrared spectroscopy (FTIR), and small angle X-ray scattering (SAXS) measurements to develop a detailed picture of methanol condensing from a dilute vapor-carrier gas mixture under the highly supersaturated conditions present in a supersonic nozzle. In our experiments, methanol condensation can be divided into three stages as the gas mixture expands in the nozzle. In the first stage, as the temperature decreases rapidly, small methanol n-mers (clusters) form, increase in concentration, and evolve in size. In the second stage, the temperature decreases more slowly, and the n-mer concentrations continue to rise. Thermodynamic and FTIR experiments cannot, however, definitively establish if the average cluster size is constant or if it continues to increase. Finally, when the vapor becomes supersaturated enough, liquid droplets form via nucleation and growth, consuming more monomer and reducing the concentration of clusters. At the point where liquid first appears, cluster formation has already consumed up to 30% of the monomer. This is significantly more than is predicted by a model that describes the vapor phase as an equilibrium mixture of methanol monomer, dimer, and tetramer. An energy balance suggests that a significant fraction of the cluster population is larger than the tetramer, while preliminary SAXS measurements suggest that these clusters contain, on average, 6 monomers. PMID:21331433

Laksmono, Hartawan; Tanimura, Shinobu; Allen, Heather C; Wilemski, Gerald; Zahniser, Mark S; Shorter, Joanne H; Nelson, David D; McManus, J Barry; Wyslouzil, Barbara E

2011-02-18

195

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

196

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

197

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

198

A Detailed Spectroscopic Analysis of the Open Cluster NGC 5460  

NASA Astrophysics Data System (ADS)

In stellar astrophysics, the study of the atmospheres of early-type stars plays a very special role since they display a variety of different phenomena, such as diffusion of chemical elements. To understand the actual role of all these physical phenomena, it is important to seek constraints from observations and for this purpose open cluster stars are particularly interesting they have: the same original chemical composition and age, and accurate age determinations. Here we present the results obtained for the stars observed in NGC 5460 with the FLAMES multi-object spectrograph of the ESO VLT. We find that the abundance of several elements increases with temperature between 7,000 and 10,500K and decreases from 10,500 to 13,000K. No correlation between abundance and ?siniwas found.

Fossati, Luca; Folsom, Colin P.; Bagnulo, Stefano; Grunhut, Jason; Landstreet, John; Kochukhov, Oleg; Paladini, Claudia; Wade, Gregg A.

199

Spectroscopic analysis of bladder cancer tissues using Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

200

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

201

[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

202

Near-Earth Objects Spectroscopic Survey (NEOSS): First Results from Mineralogical Analysis  

NASA Astrophysics Data System (ADS)

We present first results obtained from our spectroscopic survey of near-Earth objects (NEOSS), comprising a total of 102 visible and near-infrared spectra of asteroids. Visible data have been recorded with the 2.5-m Nordic Optical Telescope (NOT), while near-infrared spectra have been taken at 3.5-m Telescopio Nazionale Galileo, both telescopes located at Observatorio del Roque de los Muchachos, in La Palma (Canary Islands). We perform a raw taxonomical classification of our objects and a first mineralogical analysis using the classical method of spectral parametrization. A statistical analysis of slope distributions is also done for those objects having featureless spectra.

De Leon, Julia; Duffard, R.; Licandro, J.; Pinilla-Alonso, N.; Serra-Ricart, M.

2006-09-01

203

Chemical analysis of exhaled human breath using a terahertz spectroscopic approach  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

204

Spectroscopic studies on the oxidative decomposition of Malachite Green using ozone  

Microsoft Academic Search

Spectroscopic studies on the oxidative decomposition of Malachite Green (MG) using ozone were investigated. Parameters such as color removal, initial dye concentration, COD reduction, reaction temperature and pH were studied to determine optimum conditions for complete MG decomposition. Complete removal of MG color was achieved within 10 min of reaction with ozone. The ozone oxidation reaction time increased as concentration

Mi-Hwa Baek; Christianah Olakitan Ijagbemi; Dong-Su Kim

2010-01-01

205

Electrochemical and spectroscopic studies of uranium(IV), -(V), and -(VI) in carbonate-bicarbonate buffers  

Microsoft Academic Search

Recently a need for more detailed knowledge of the chemistry of actinide ions in basic media has arisen in connection with deducing their chemistry in the environment. In this work the results of polarographic, cyclic voltammetric, and spectroscopic studies of U(IV), -(V), and -(VI) in carbonate and bicarbonate media are reported. Polarographic studies were in excellent agreement with those reported

D. W. Wester; J. C. Sullivan

1980-01-01

206

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

NASA Astrophysics Data System (ADS)

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

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

2005-02-01

207

Synthesis, spectroscopic (FT-IR, FT-Raman, 13C, 1H, UV) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone  

NASA Astrophysics Data System (ADS)

The title compound, 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone (2HPN4MPN) was synthesized and characterized by FT-IR, FT-Raman, UV-Vis and 1HNMR, 13CNMR spectral analysis. The molecular geometry, harmonic vibrational frequencies and bonding features of the title compound in the ground state are computed at three parameter hybrid functional Lee-Yang-Parr/6-311++G(d,p) levels of theory. The most stable conformer of 2HPN4MPN is identified from the computational results. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The UV-Vis spectrum was recorded in chloroform solution. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) complements the experimental findings. The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. In addition, DFT calculations of the compound, Molecular Electrostatic Potential (MEP), Natural Bond Orbital analysis (NBO) and non-linear optical (NLO) properties are performed at B3LYP/6-311++G(d,p) level of theory. Finally, the calculations are applied to simulated FT-IR and FT-Raman spectra of the title compound which show good agreement with observed spectra.

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

2013-05-01

208

Spitzer IRS spectroscopic studies of dust composition of protoplanetary disks  

NASA Astrophysics Data System (ADS)

I present an analysis of mid-infrared spectra of T Tauri stars observed largely as part of the Spitzer IRS Disks Guaranteed Time Observing program, focusing on the composition of the solid-state dust in the upper layers of the protoplanetary disks surrounding these stars. First, I quickly summarize our understanding of the early evolution of our Solar System, with special regard to studies of primitive Solar System dust, and I review studies of Young Stellar Objects. I describe how the data are reduced via spectral extraction methods designed to yield high quality spectra. Next, I provide some background on radiative transfer models of protoplanetary disks to justify the use of simplified dust emission models to measure the dust composition of the upper layers of these disks. I apply these models to five protoplanetary disk spectra that each show evidence for a high abundance of silica dust, in order to identify the polymorphs, or crystalline forms, of silica most likely giving rise to the distinctive features in the spectra, and I discuss the implications for processing of dust in protoplanetary disks. This is followed by a discussion on finding the optimal dust grain opacities to use in modeling protoplanetary disks and some limitations of the simple dust emission models I use. Finally, I discuss dust emission models fit to spectra of sixty-five Class II Young Stellar Objects in the Taurus-Auriga star-forming region and the implications for grain growth, dust processing, and protoplanetary disk evolution.

Sargent, Benjamin A.

2009-06-01

209

[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

210

Near Infrared Photometric and Optical Spectroscopic Study of 22 Low Mass Star Clusters embedded in Nebulae  

NASA Astrophysics Data System (ADS)

Among the star clusters in the Galaxy, those embedded in nebulae represent the youngest group that has only recently been explored. The analysis of a sample of 22 candidate embedded stellar systems in reflection nebulae and/or HII environments is presented. We employed optical spectroscopic observations of stars in the directions of the clusters together with near infrared photometry from the 2MASS catalogue. Our analysis is based on source surface density, colour-colour diagram and on theoretical pre-main sequence isochrones. We take into account the field star contamination by carrying out a statistical subtraction. The studied objects have the characteristics of low mass systems. We derive their fundamental parameters. Most of the cluster ages turned out to be younger than 2 Myr. The studied embedded stellar systems in reflection nebulae and/or HII region complexes do not have stars of spectral types earlier than B. The total stellar masses locked in the clusters are in the range 20-220 solar masses. They are found to be gravitationally unstable and are expected to dissolve in a timescale of a few Myr (Soares et al. 2008, A&A, 478, 419).

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

2009-05-01

211

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

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

212

Elemental and spectroscopic methods with chemometric analysis for characterizing composition and transformation of dissolved organic matter during chicken manure composting.  

PubMed

Dissolved organic matter was extracted from chicken manure after 1, 8, 16, 28 and 40 days of composting and characterized by combining elemental and spectroscopic methods with chemometric analysis to investigate the evolution of composting materials. The elemental and spectroscopic analysis results showed that the composting process was characterized by the biodegradation of aliphatics, polysaccharide and proteins, as well as by the synthesis of aromatic structures, humic-like substances and macromolecules. Principal component analysis and correlation analysis indicated that the data from elemental and spectroscopic analysis fell into three main groups, and corresponded to the biodegradation, aromatization, and humification and polymerization state of the composting materials. Hierarchical cluster analysis indicated rapid biodegradation of organic matter during the first eight days, and the formation of aromatic structures, humic-like materials and macromolecules in dissolved organic matter after eight days. PMID:23240197

He, Xiao-Song; Xi, Bei-Dou; Jiang, Yong-Hai; Li, Ming-Xiao; Yu, Hui-Bin; An, Da; Yang, Yu; Liu, Hong-Liang

2012-09-01

213

Spectroscopic study on binding of rutin to human serum albumin  

NASA Astrophysics Data System (ADS)

Steady-state and time-resolved fluorescence spectroscopy techniques were used to study the interaction of the flavonoid rutin with human serum albumin (HSA) as well as spectral properties of the protein-bound flavonoid. Both quenching of the intrinsic fluorescence of the protein (Trp214) and the ligand fluorescence, appearing upon complexation with HSA, were used to determine binding parameters. The binding constant determined from the quenching of the Trp214 fluorescence by rutin is equal to 6.87 ± 0.22 × 104 M-1 and that obtained from the fluorescence of HSA-bound rutin is 3.8 ± 0.4 × 104 M-1. Based on the Job plot analysis, the 1:1 binding stoichiometry for the HSA-rutin complex was determined. The efficient quenching of the Trp214 fluorescence by rutin, fluorescence resonance energy transfer from excited Trp214 to rutin, and competitive binding of warfarin indicate that the binding site for the flavonoid is situated within subdomain IIA of HSA. The presence of the sugar moiety in the flavonoid molecule reduces affinity of rutin for binding to HSA but does not affect the binding stoichiometry and location of the binding site compared with aglycone analogues.

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

2007-10-01

214

Spectroscopic study of major components of dissolved organic matter naturally occurring in water  

Microsoft Academic Search

Natural organic compounds are present in significant concentration in all types of water. The spectroscopic study of dissolved organic matter and its major components is important for applications of lidar remote sensing techniques for water quality measurements. In this paper, fluorescence emission and excitation spectra, as well as absorption spectra for commercially available analogues of major components of gelbstoff are

Svetlana V. Patsayeva; Rainer Reuter

1995-01-01

215

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

National Technical Information Service (NTIS)

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

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

1995-01-01

216

AN OVERVIEW OF MOLECULAR SPECTROSCOPIC STUDIES ON THEOBROMINE AND RELATED ALKALOIDS  

Microsoft Academic Search

An overview of the recent molecular spectroscopic work on the methylxanthine alkaloid, theobromine and its two closely related relatives, caffeine and theophylline is presented. The role of molecular spectroscopy in studies of the coordination chemistry of these methylxanthine compounds is also discussed briefly.

Brij B. Tewari; Guillaume Beaulieu-Houle; Aaron Larsen; Rosine Kengne-Momo; Karine Auclair; Ian S. Butler

2011-01-01

217

A spectroscopic study of laser injected metallic impurities into TFR tokamak plasmas  

NASA Astrophysics Data System (ADS)

Vanadium, chromium, and nickel have been injected into TFR tokamak plasmas by using the laser injection technique. Spectroscopic studies show that the particle confinement time increases as the impurities diffuse towards the plasma center. Moreover, the confinement time of laser-injected vanadium impurities has been found to increase with the mass of background plasma ions.

TFR Group

1982-01-01

218

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

Microsoft Academic Search

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

Takahiro Suzuki; Sadao Adachi

1994-01-01

219

An Overview of Molecular Spectroscopic Studies on Theobromine and Related Alkaloids  

Microsoft Academic Search

Abstract: An overview of the recent molecular spectroscopic work on the methylxanthine alkaloid theobromine and its two closely related relatives, caffeine and theophylline, is presented. The role of molecular spectroscopy in studies of the coordination chemistry of these methylxanthine compounds is also briefly discussed.

Brij B. Tewari; Guillaume Beaulieu-Houle; Aaron Larsen; Rosine Kengne-Momo; Karine Auclair; Ian S. Butler

2012-01-01

220

Spectroscopic studies on the interaction of cinnamic acid and its hydroxyl derivatives with human serum albumin  

Microsoft Academic Search

Cinnamic acid and its derivatives possess various biological effects in remedy of many diseases. Interaction of cinnamic acid and its hydroxyl derivatives, p-coumaric acid and caffeic acid, with human serum albumin (HSA), and concomitant changes in its conformation were studied using fluorescence and Fourier transform infrared spectroscopic methods. Fluorescence data revealed the presence of one binding site on HSA for

Jiang Min; Xie Meng-Xia; Zheng Dong; Liu Yuan; Li Xiao-Yu; Chen Xing

2004-01-01

221

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

2013-07-02

222

Vibrational spectroscopic study of hydroxylpyromorphite-hydroxylmimetite solid solutions  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

223

Solvated Crystalline Forms of Nevirapine: Thermoanalytical and Spectroscopic Studies  

PubMed Central

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

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

2010-01-01

224

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

PubMed

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(H(2)O)(4)](NO(3))(3), M=Cr(III) and Fe(III), [NiL(H(2)O)(4)](NO(3))(2), [ML(H(2)O)(2)](NO(3))(2), M=Zn(II) and Cd(II), [Cl(2)Pd(?-Cl)(2)PdL], [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 (1)H 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). PMID:23291195

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

2012-12-27

225

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

226

Temporal correlation scheme for spectroscopic gas analysis using multimode diode lasers  

NASA Astrophysics Data System (ADS)

The reliability of diode lasers used in spectroscopic applications is limited by their intrinsic multimode and mode-jump behavior when wavelength-tuned by current or temperature. We report on a scheme for gas analysis based on temporal correlation between absorption signals from an unknown external and a known reference gas concentration, simultaneously recorded when the diode laser wavelength is temperature-tuned across absorption features of the gas of interest. This procedure, which does not require any knowledge of the exact spectrum, also eliminates light intensity fluctuations due to mode competition. The method is illustrated for atmospheric oxygen absorption applied to diffusion measurements.

Somesfalean, G.; Sjöholm, M.; Persson, L.; Gao, H.; Svensson, T.; Svanberg, S.

2005-05-01

227

Principal component and spatial correlation analysis of spectroscopic-imaging data in scanning probe microscopy  

NASA Astrophysics Data System (ADS)

An approach for the analysis of multi-dimensional, spectroscopic-imaging data based on principal component analysis (PCA) is explored. PCA selects and ranks relevant response components based on variance within the data. It is shown that for examples with small relative variations between spectra, the first few PCA components closely coincide with results obtained using model fitting, and this is achieved at rates approximately four orders of magnitude faster. For cases with strong response variations, PCA allows an effective approach to rapidly process, de-noise, and compress data. The prospects for PCA combined with correlation function analysis of component maps as a universal tool for data analysis and representation in microscopy are discussed.

Jesse, Stephen; Kalinin, Sergei V.

2009-02-01

228

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

PubMed

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

Haroun, Mahdi; Idris, Azni; Omar, Syed

2008-09-30

229

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

PubMed

Raman spectroscopy is a valuable and complementary tool for studying geometrically frustrated magnetic systems due to the intrinsic spin-phonon coupling. Here, we report on a Raman spectroscopic study of the geometrically frustrated spin 1/2 antiferromagnet microcrystalline clinoatacamite Cu2(OH)3Cl, focusing on the anomalous transition into the intermediate phase at T(c1) = 18.1 K. By measuring the temperature-dependent (295-4 K) full spectral profiles and main representative modes in spectral regions from 4000 to 95 cm(-1), we observed probable signatures of successive magnetic transitions near T(c1) = 18 K and T(c2) = 6.4 K in the Raman band frequencies and peak widths of the representative modes. Further, we observed a pronounced Raman spectroscopy background featuring a broad continuum at all temperatures. A quantitative analysis reveals that spin fluctuations may exist on a picosecond time scale in the intermediate phase. The short time scale falls out of the ?SR time window; therefore, in the intermediate phase, the ?SR study as reported in (2005 Phys. Rev. Lett. 95 057201) apparently only probed the local field of the ordered spins but overlooked the quickly fluctuating ones. This is likely to give a reasonable explanation of the fact that only a small entropy release occurs at T(c1) = 18 K although a long-range order is formed. PMID:23719338

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

2013-05-30

230

FTIR-based spectroscopic analysis in the identification of clinically aggressive prostate cancer  

PubMed Central

Fourier transform infrared (FTIR) spectroscopy is a vibrational spectroscopic technique that uses infrared radiation to vibrate molecular bonds within the sample that absorbs it. As different samples contain different molecular bonds or different configurations of molecular bonds, FTIR allows us to obtain chemical information on molecules within the sample. Fourier transform infrared microspectroscopy in conjunction with a principal component-discriminant function analysis (PC-DFA) algorithm was applied to the grading of prostate cancer (CaP) tissue specimens. The PC-DFA algorithm is used alongside the established diagnostic measures of Gleason grading and the tumour/node/metastasis system. Principal component-discriminant function analysis improved the sensitivity and specificity of a three-band Gleason score criterion diagnosis previously reported by attaining an overall sensitivity of 92.3% and specificity of 99.4%. For the first time, we present the use of a two-band criterion showing an association of FTIR-based spectral characteristics with clinically aggressive behaviour in CaP manifest as local and/or distal spread. This paper shows the potential for the use of spectroscopic analysis for the evaluation of the biopotential of CaP in an accurate and reproducible manner.

Baker, M J; Gazi, E; Brown, M D; Shanks, J H; Gardner, P; Clarke, N W

2008-01-01

231

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

232

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

233

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

234

Fouriertransform Raman spectroscopic study of frankincense and myrrh  

Microsoft Academic Search

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

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

1997-01-01

235

CD Spectroscope  

NSDL National Science Digital Library

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

University, Colorado S.

2009-01-01

236

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

PubMed

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. PMID:22070992

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

2011-10-17

237

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

238

Some polyhydroxy azo azomethine derivatives of salicylaldehyde: Synthesis, characterization, spectroscopic, molecular structure and antimicrobial activity studies  

NASA Astrophysics Data System (ADS)

Some new substituted polyhydroxy azo azomethine compounds were prepared by reaction of tris(hydroxymethyl)aminomethane with (E)-2-hydroxy-5-(phenyldiazenyl) benzaldehyde and its substituted derivatives. The structures of azo and azo azomethine compounds were determined by IR, UV vis, 1H NMR and 13C NMR spectroscopic techniques, and/or X-ray diffraction studies. According to IR spectra, all azo azomethine compounds adopt keto form in solid state. UV vis analysis has shown the presence of keto enol tautomerism in solution for all azo azomethine compounds, except that for nitro substituted derivative, enol form is dominantly favored in solution. At the same time, above mentioned derivative compounds were studied in vitro for their antimicrobial properties. Among the phenylazosalicylaldehyde series compound tested, 4-phenylazosalicylaldehyde, 4-(3-chlorophenylazo)salicylaldehyde, 4-(2-chlorophenylazo)salicylaldehyde, 4-(4-fluorophenylazo)salicylaldehyde, 4-(3-chlorophenylazo)salicylaldehyde and 4-(4-ethylphenylazo)salicylaldehyde showed a weak antimicrobial activity only against gram positive bacteria. On the contrary, phenylazosalicylaldehyde series compounds were reacted tris(hydroxmethyl)aminomethane, that exhibited a strong antimicrobial activity against gram positive bacteria, yeast and mould. Moreover, while the 2-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylimino]methyl}phenol did not show an inhibition on tested microorganism, the addition of phenyldiazine groups to 2-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylimino]methyl}phenol resulted in a strong increases in antimicrobial activity.

Odaba?o?lu, Mustafa; Albayrak, Çi?dem; Özkanca, Re?it; Aykan, Fatma Zehra; Lonecke, Peter

2007-09-01

239

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 (?-Fe2O3), magnetite (Fe3O4) and Fe2+ and Fe3+ mullite/silicates/glasses.

Harchand, K. S.; Raj, D.

1993-04-01

240

Spectroscopic studies of the effects of anticancer drug mitoxantrone interaction with calf-thymus DNA.  

PubMed

Mitoxantrone (MTX) (1,4-dihydroxy-5,8-bis[[2-[(2-hydroxyethyl)amino]ethyl]amino]-9,10-anthracenedione) is a synthetic antineoplastic drug, widely used as a potent chemotherapeutic agent in the treatment of various types of cancer. It is structurally similar to classical anthracyclines. Widespread interest in the anticancer agent mitoxantrone has arisen because of its apparent lower risk of cardio-toxic effects compared to the naturally occurring anthracyclines. In the present work, we investigated the interaction of mitoxantrone with DNA in the buffer solution at physiological pH using Fourier transform infrared (FTIR), UV-Visible absorption and circular dichroism spectroscopic techniques. FTIR analysis revealed the intercalation of mitoxantrone between the DNA base pairs along with its external binding with phosphate-sugar backbone. The binding constant calculated for mitoxantrone-DNA association was found to be 3.88×10(5)M(-1) indicating high affinity of drug with DNA double helix. Circular dichroism spectroscopic results suggest that there are no major conformational changes in DNA upon interaction with drug except some perturbations in native B-DNA at local level. The present work shows the capability of spectroscopic analysis to characterize the nature of drug-biomolecule complex and the effects of such interaction on the structure of biomolecule. PMID:23266050

Agarwal, Shweta; Jangir, Deepak Kumar; Mehrotra, Ranjana

2012-12-06

241

Infrared Spectroscopic Studies on Amorphous and Crystalline Lanthanum Aluminoborates  

NASA Astrophysics Data System (ADS)

The development of lanthanum aluminoborate crystalline phase of LaAl2.03B4O10.5 (124) composition from the amorphous xerogels prepared by sol-gel technique has been characterized by thermal analysis and infrared spectroscopy. Thermal analysis evidenced continuous weight losses up to 800°C as a result of nitrates decomposition, glycerol combustion and dehydroxylation. The crystallization of amorphous xerogels occurs between 760 and 860°C. The IR data indicate that the local structure dramatically modifies as crystalline phases are developed from the amorphous xerogels. The major changes occur in the boron surrounding where, from the most borons which are three-coordinated in amorphous xerogels, almost only tetra-coordinated species appear in the crystalline samples. While in amorphous xerogels, aluminum occurs as hexa-, penta- and tetra-coordinated by oxygen, in the crystalline samples obtained from lanthanum aluminoborates, amorphous precursors of composition corresponding to 124-lanthanum aluminoborate phase aluminum, it is preponderantly penta- and hexa-coordinated.

Simon, S.; Grecu, R.; Simon, V.

242

In vivo localized proton spectroscopic studies of human gastrocnemius muscle  

Microsoft Academic Search

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

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

1988-01-01

243

Spectroscopic studies of swift heavy ion irradiated nanophase mullite  

Microsoft Academic Search

Photoluminescence (PL) studies of 100 MeV swift Ag8+ ion bombarded combustion synthesized nanophase mullite has been studied at room temperature (RT) and the results are reported here. A pair of PL bands, one broad band centres at ˜550 nm and another sharp one at ˜690 nm are observed with excitation by a 442 nm laser beam. However, when the sample

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

2006-01-01

244

Regionally Specific Neuronal Pathology in Untreated Patients with Schizophrenia: A Proton Magnetic Resonance Spectroscopic Imaging Study  

Microsoft Academic Search

Background: Proton magnetic resonance spectroscopic imaging (1H-MRSI) studies have reported reductions of N-acetyl aspartate (NAA), a marker of neuronal integrity, in the hippocampal region (HIPPO) and dorsolateral prefrontal cortex (DLPFC) of pharmacologically treated patients with schizophrenia. The purpose of the present study was twofold: to exclude drug treatment as a source of the previous findings and to examine NAA relative

Alessandro Bertolino; Joseph H. Callicott; Igor Elman; Venkata S. Mattay; Gioacchino Tedeschi; Joseph A. Frank; Alan Breier; Daniel R. Weinberger

1998-01-01

245

Spectroscopic studies of the size and composition of single aerosol droplets  

NASA Astrophysics Data System (ADS)

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

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

246

Spectroscopic studies on the interaction of bovine serum albumin with surfactants and apigenin.  

PubMed

The binding of apigenin (Ap) to bovine serum albumin (BSA) has been studied using the methods of fluorescence spectroscopy and UV-vis absorption spectroscopy. The spectroscopic analysis of the quenching mechanism indicates that the quenching constants are inversely correlated with the temperatures and the quenching process could result from a static interaction. The type of interaction force was discussed and the binding site of Ap was in site I (subdomain IIA) of BSA. The thermodynamic parameters ?H and ?S are -42.02kJ mol(-1) and -48.31J mol(-1)K(-1), respectively and the negative ?G implying that the binding interaction was spontaneous. The distance r between BSA and Ap was calculated according to Förster's theory and the value is 3.44nm. The synchronous and three-dimensional fluorescence spectra show that the binding of Ap to BSA could lead to the changes in the conformation and microenvironment of BSA. At the same time, the effects of ionic surfactants on the interaction of Ap and BSA have also been investigated. PMID:22561754

Zhao, Xu-Na; Liu, Yi; Niu, Li-Yuan; Zhao, Chen-Ping

2012-03-03

247

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

248

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

NASA Astrophysics Data System (ADS)

Propofol (2,6-di-isopropylphenol) is probably the most widely used general anesthetic. Previous studies focused on its complexes containing 1 and 2 water molecules. In this work, propofol clusters containing three water molecules were formed using supersonic expansions and probed by means of a number of mass-resolved laser spectroscopic techniques. The 2-color REMPI spectrum of propofol.(H2O)3 contains contributions from at least two conformational isomers, as demonstrated by UV/UV hole burning. Using the infrared IR/UV double resonance technique, the IR spectrum of each isomer was obtained both in ground and first excited electronic states and interpreted in the light of density functional theory (DFT) calculations at M06-2X/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels. The spectral analysis reveals that in both isomers the water molecules are forming cyclic hydrogen bond networks around propofol's OH moiety. Furthermore, some evidences point to the existence of isomerization processes, due to a complicated conformational landscape and the existence of multiple paths with low energy barriers connecting the different conformers. Such processes are discussed with the aid of DFT calculations.

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

2012-08-01

249

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

PubMed

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

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

2012-08-21

250

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

251

Spectroscopic and catalytic study of P-modified ZSM-5  

SciTech Connect

Postsynthesis modification of ZSM-5 with phosphorus was performed by gas-phase adsorption of triphenylphosphine. IR spectra of adsorbed pyridine indicated an interaction of phosphorus species with Bronsted acid sites. ESCA analysis of noncalcined catalysts suggests a model for this interaction. A quantitative treatment of ESCA intensity ratios for the calcined catalysis before and after grinding allows one to calculate the size and loading of both extraparticle and intra-pore-lattice (IPL) phosphorus oxide particles. The IPL loading was found to be vary close to the loading of exchange phosphorus calculated from the IR of adsorbed pyridine. The product distribution of MTG conversion was found to be correlated with the extent of Bronsted acid site poisoning following exchange with phosphorus species.

Rahman, A.; Lemay, G.; Adnot, A.; Kaliaguine, S. (Universite Laval, Quebec (Canada))

1988-08-01

252

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...

253

Spectroscopic studies of swift heavy ion irradiated nanophase mullite  

Microsoft Academic Search

Photoluminescence (PL) studies of 100MeV swift Ag8+ ion bombarded combustion synthesized nanophase mullite has been studied at room temperature (RT) and the results are reported here. A pair of PL bands, one broad band centres at ?550nm and another sharp one at ?690nm are observed with excitation by a 442nm laser beam. However, when the sample is excited with 326nm

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

2006-01-01

254

Structural, functional and spectroscopic MRI studies of methamphetamine addiction.  

PubMed

This chapter reviews selected neuroimaging findings related to long-term amphetamine and methamphetamine (MA) use. An overview of structural and functional (fMRI) MR studies, Diffusion Tensor Imaging (DTI), Magnetic Resonance Spectroscopy (MRS) and Positron Emission Tomography (PET) studies conducted in long-term MA abusers is presented. The focus of this chapter is to present the relevant studies as tools to understand brain changes following drug abstinence and recovery from addiction. The behavioral relevance of these neuroimaging studies is discussed as they relate to clinical symptoms and treatment. Within each imaging section this chapter includes a discussion of the relevant imaging studies as they relate to patterns of drug use (i.e., duration of MA use, cumulative lifetime dose and time MA abstinent) as well as an overview of studies that link the imaging findings to cognitive measures. In our conclusion we discuss some of the future directions of neuroimaging as it relates to the pathophysiology of addiction. PMID:22094881

Salo, Ruth; Fassbender, Catherine

2012-01-01

255

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

PubMed

This paper reports the results of the characterization of red soils in relation to the sorption of H2S from coal gas at 500 degrees C by spectroscopic techniques in order to provide more information on red soils' structural change both before and after reaction. In addition, by-products analysis has also been studied using Fourier transform infrared (FTIR) spectroscopy. Before and after the experiments the red soils were characterized with X-ray powder diffraction (XRPD), energy dispersion spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and FTIR spectroscopy. XRPD results indicate that iron oxide species disappear from the original to reacted red soil. EDS analysis shows that a significant amount of sulfur is present in the reacted red soil, which is in agreement with the results of the elemental analysis and the calculated value based on breakthrough curve. XPS regression fitting results further indicate that sulfur retention may be associated with the iron oxides. S 2p XPS fittings point out that the major sulfur species present in the reacted red soil are composed of S(-2), elemental sulfur, polysulfide, sulfite and sulfate. Additionally, the binding energy of iron shifts to a lower position for the reacted red soil, which indicates that iron oxides in the original red soil have been converted into iron sulfide. Appreciable amounts of the by-products CO2, SO2 and COS are detected by on-line FTIR spectroscopy during the initial and later stages of the sorption process. The formation of CO2 is related to the water-shift reaction, and SO2 is probably attributable to the reaction of organic matters and H2S. The concentration of COS is quantified by GC/FPD and found it to be about 350 ppm, which is close to the equilibrium concentration of the reaction of inlet CO and H2S at a temperature of 500 degrees C. PMID:15911419

Ko, T H; Chu, H

2004-12-18

256

Spectroscopic studies on pure and histidine functionalized MWCNTs  

NASA Astrophysics Data System (ADS)

Electron spin resonance (ESR), Fourier transform infrared (FTIR) and Ultraviolet-visible (UV-Vis) studies were carried out for pure and histidine functionalized MWCNTs (0.2, 0.4 and 0.6 M concentration of histidine). EPR absorption spectral data found to be best fit for the Gaussian lineshape. The g-values indicate the presence of magnetic impurities in the samples and the interaction between the localized electrons and delocalized electrons in the nanotubes trapped at defects or magnetic ions site. The electron spin concentration decreases with increasing concentration of histidine, which implies that the unpaired electron in the MWCNTs undergo a reduction process in the histidine functionalized MWCNTs. FTIR study confirms the presence of functional groups in pure and histidine functionalized MWCNTs. UV-Vis study reveals that the formation of histidine-MWCNTs charge transfer complex.

Mathavan, T.; Kanimozhi, C. V.; Jothi Rajan, M. A.; Umapathy, S.; Dhas, M. Kumara; Franklin Benial, A. Milton

2013-06-01

257

EXAFS spectroscopic studies of uranium(VI) oxide precipitates  

SciTech Connect

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

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

1996-04-01

258

Femtosecond spectroscopic study of carminic acid DNA interactions  

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

259

Spectroscopic study of candidate Be stars in the Magellanic Clouds  

NASA Astrophysics Data System (ADS)

The Magellanic Clouds (MCs) are known to be abundant in Be stars. Since the MCs are metal poor than in our Galaxy, it will be interesting to understand the properties of Be stars in these galaxies. Mennickent et al. (2002) and Sabogal et al. (2005) have identified many Be star-like variables showing light curves similar to those of Galactic Be stars (called type-4 stars) and also others presenting different kinds of light curves (called type-1, type-2, type-3 stars). We report the results of spectral analysis of a subset of the above Be candidate stars in the SMC and the LMC. Spectra were obtained for 68 candidate stars in the SMC and 38 candidate stars in the LMC. Observations were made using the 1.5 m CTIO Telescope and 2.5 m LCO Telescope. Our sample includes stars of type 1, 2 and 3 of the LMC and the SMC. The spectral features are used to identify their spectral class and to see whether they show some properties of Be stars.

Paul, Kodiyan Thomas; Subramaniam, A.; Mathew, B.; Mennickent, R. E.; Sabogal, B.

260

Spectroscopic and computational study of a new isomer of salinomycin  

NASA Astrophysics Data System (ADS)

I have synthesized a new derivative of salinomycin.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).A potential mechanism of the rearrangement was proposed.

Pankiewicz, Rados?aw

2013-09-01

261

Raman spectroscopic studies of carbon in extra-terrestrial materials  

Microsoft Academic Search

The measurements obtained here indicate ways in which micro-Raman spectroscopy can be used to elucidate structural characteristics and distribution of carbon in meteorites and interplanetary dust particles (IDPs). Existing information about structurally significant aspects of Raman measurements of graphite is combined with structurally relevant findings from the present micro-Raman studies of carbons prepared by carbonization of polyvinylidine chloride (PVDC) at

John Macklin; Donald Brownlee; Sherwood Chang; Ted Bunch

1990-01-01

262

Spectroscopic studies of terrestrial impact materials: Preparation for Popigai expedition  

NASA Astrophysics Data System (ADS)

Terrestrial craters give us an excellent opportunity of direct analisys as opposed to craters out of the E arth. However, on the Earth there are only few sites where traces of strong impacts event could be studied in the fi eld. The traces of ancient impacts are better preserved in the frozen subsoil at subpolar latitudes. One of such sites is Popigai crater, located in subpolar Siberia, Russia, presumably caused by a giant impactor 35 Ma ago. This astrobleme gives a good chance to observe in situ the asteroid crater, impact materials and other consequenses of great energy deposition. T he crater was thoroughly studied during last few decades due to impact diamond inventories associated with it [1]. However a number of problems remain unresolved and wait for further studies: the physics and chemistry of impactites and impact breccias; mineral components with metamorphic rocks affected by great shock and impactites; material ejecta; structural forms invoked by crater formation; problems of remote sensing studies and problems related to comparative planetology. In the framework o f Europlanet program, we plan the expedition to Popigai site scheduled to 2012.

Evdokimova, N. A.; Rodin, A. V.; Masaitis, V. L.; Timofeev, I. S.; Roste, O. Z.; Korablev, O. I.; Dolnikov, G. G.

2011-10-01

263

Spectroscopic Study of Host-Guest Inclusion Complexes  

Microsoft Academic Search

A host-guest complex is formed by a host molecule encapsulating a guest molecule within it. The host materials in this study are basket-shaped structures, known as cyclodextrins, which can easily incorporate a variety of guests, such as drug molecules. These inclusion complexes made with cyclodextrins and drugs can be developed to have different release rates within the body. The cyclodextrin

Jenessa Lucas; Jennifer Holt

2012-01-01

264

An infrared and Raman spectroscopic study of natural zinc phosphates  

Microsoft Academic Search

Zinc phosphates are important in the study of the phosphatisation of metals. Raman spectroscopy in combination with infrared spectroscopy has been used to characterise the zinc phosphate minerals. The minerals may be characterised by the patterns of the hydroxyl stretching vibrations in both the Raman and infrared spectra. Spencerite is characterised by a sharp Raman band at 3516cm?1 and tarbuttite

Ray L Frost

2004-01-01

265

Spectroscopic Study of Small Absorptions in Optical Coatings.  

National Technical Information Service (NTIS)

This report concerns research performed by the Utah University surface physics group for the Air Force Weapons Laboratory (AFWL), Kirtland Air Force Base, New Mexico. It is a supplement to AFWL-TR-79-197. It reports the continued study of thorium fluoride...

W. N. Hansen

1982-01-01

266

Synchronous fluorescence spectroscopic study of solvatochromic curcumin dye  

Microsoft Academic Search

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

Digambara Patra; Christelle Barakat

2011-01-01

267

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

268

Natural fluorescence of white blood cells: spectroscopic and imaging study  

Microsoft Academic Search

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

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

1995-01-01

269

Raman spectroscopic study of a substituted poly(phosphazene)  

Microsoft Academic Search

Polyphosphazenes present a range of unique and fascinating physical properties, including thermotropic behaviour, which are highly dependent both on the type of substitution at the P atom in the inorganic backbone, and the thermal history of the material. Recent technological advances have allowed us to study this group of polymers using vibrational spectroscopy. Fourier transform (FT) Raman spectra have been

Gary Ellis; M. Angeles Gómez; Carlos Marco; José G. Fatou; Robert C. Haddon

1991-01-01

270

Quantitative spectroscopic strain analysis of AlGaAs-based high-power diode laser devices  

NASA Astrophysics Data System (ADS)

Results of quantitative spectroscopic analysis of packaging-induced strain in In{0.06}Ga{0.86}Al{0.08}As/Ga{0.7}Al{0.3}As/GaAs high-power `cm-bars' diode laser arrays are presented. Theoretically, the influence on the results of particular device structure properties, such as intrinsic strain, is analyzed. We compare these theoretical results, which are based on a unaxial stress model, with photocurrent data. For In-soldered devices on copper heatsinks, we find a strain difference of (0.050± 0.015)% between edge and center of the device. Almost complete strain-relaxation toward the device edges is experimentally demonstrated. The general approach is also applicable to the analysis of all data that refer to changes of the electronic bandstructure, such as absorption and photoluminescence.

Tomm, J. W.; Gerhardt, A.; Biermann, M. L.; Holland, J. P.

2004-07-01

271

Raman spectroscopic study of left-handed Z-RNA  

SciTech Connect

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

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

1987-12-29

272

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

273

Virgin and recycled engine oil differentiation: a spectroscopic study.  

PubMed

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

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

2008-02-20

274

A computational infrared spectroscopic study of graphene oxide  

NASA Astrophysics Data System (ADS)

Infrared (IR) spectroscopy is an important means to study the atomic structure of graphene oxide (GO). In this study, computational simulations of GO IR spectra are carried out. The widely accepted Lerf model gives most experimental IR characteristics correctly except the strong C=O stretching peak. This is a result of the absence of carbonyl groups in the interior part of GO. Defects or small oxidative debris should thus be introduced into GO models to accommodate more carbonyl groups. Unfortunately, even for those with defects or oxidative debris included, most previous models in the literature still fail to give a correct IR response. Actually, the C=O stretching frequency is found to be very sensitive to local chemical environment. Therefore, to introduce defects or oxidative debris into GO models, certain constrains apply.

Yin, Di; Lu, Ning; Li, Zhenyu; Yang, Jinlong

2013-08-01

275

A computational infrared spectroscopic study of graphene oxide.  

PubMed

Infrared (IR) spectroscopy is an important means to study the atomic structure of graphene oxide (GO). In this study, computational simulations of GO IR spectra are carried out. The widely accepted Lerf model gives most experimental IR characteristics correctly except the strong C=O stretching peak. This is a result of the absence of carbonyl groups in the interior part of GO. Defects or small oxidative debris should thus be introduced into GO models to accommodate more carbonyl groups. Unfortunately, even for those with defects or oxidative debris included, most previous models in the literature still fail to give a correct IR response. Actually, the C=O stretching frequency is found to be very sensitive to local chemical environment. Therefore, to introduce defects or oxidative debris into GO models, certain constrains apply. PMID:24007026

Yin, Di; Lu, Ning; Li, Zhenyu; Yang, Jinlong

2013-08-28

276

Spectroscopic study of sorption of nitrogen heterocyclic compounds on phyllosilicates  

Microsoft Academic Search

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

Sandip Chattopadhyay; Samuel J. Traina

1999-01-01

277

Raman spectroscopic study of the synthesis of zeolite Y  

SciTech Connect

The formation of zeolite Y from colloidal silica and soluble silicate species was investigated by Raman spectroscopy. The role of aging of the reactant mixture was studied. During the nucleation period, the solid amorphous phase consists of predominantly six-membered aluminosilicate rings, which act as building blocks for the formation of zeolite Y. It is essential to have polymeric, highly condensed silicate units as a reactant if zeolite Y crystallization is to take place.

Dutta, P.K.; Shieh, D.C.; Puri, M.

1987-04-23

278

X-Ray Spectroscopic Study of Astrophysical Plasma  

NASA Astrophysics Data System (ADS)

This paper discusses on extremely low-density space plasmas with the relation to laboratory plasmas. Extremely low density and large volume in the space provide us with a good laboratory to study elemental process, in particular those in non-equilibrium plasmas or very quick transient phenomena, which are difficult to access in ground laboratories. We demonstrate these aspects using the ASCA data, and discuss briefly on future prospects of space plasmas.

Koyama, Katsuji

2000-01-01

279

Cyclodextrins-Kaempferol Inclusion Complexes: Spectroscopic and Reactivity Studies  

Microsoft Academic Search

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

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

2011-01-01

280

Spectroscopic study of small absorptions in optical coatings  

Microsoft Academic Search

This report concerns research performed by the Utah University surface physics group for the Air Force Weapons Laboratory (AFWL), Kirtland Air Force Base, New Mexico. It is a supplement to AFWL-TR-79-197. It reports the continued study of thorium fluoride (ThF4) as an optical coating, showing that the moisture found in the ThF4 films probably originated from the preparation itself, and

W. N. Hansen

1982-01-01

281

Reduction of selenite on iron surfaces: Amicro-spectroscopic study  

Microsoft Academic Search

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)

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

2003-01-01

282

Ultraviolet Spectroscopic Study of the Cellulose Functionalization with Silanes  

Microsoft Academic Search

The reaction of a cellulosic material (Whatman no. 42 filter paper) with two silanes was studied by Diffuse Reflectance Ultraviolet-Visible Spectroscopy and Diffuse Reflectance Fourier Transform Infrared Spectroscopy. The silanes were 3-aminopropyltriethoxysilane (APS) and methyltrimethoxysilane (MS), a silane with a non-reactive organofunctional group. The use of organic peroxides was required in order to achieve an efficient cellulose modification with the

M. U. de la Orden; M. C. Matías; C. González Sánchez; J. Martínez Urreaga

1999-01-01

283

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

284

Spectroscopic, thermal and biological studies on some trivalent ruthenium and rhodium NS chelating thiosemicarbazone complexes.  

PubMed

The synthetic, spectroscopic, and biological studies of sixteen ring-substituted 4-phenylthiosemicarbazones and 4-nitrophenyl-thiosemicarbazones of anisaldehyde, 4-chlorobenzaldehyde, 4-fluorobenzaldehyde, and vanillin with ruthenium(III) and rhodium(III) chlorides are reported here. Their structures were determined on the basis of the elemental analyses, spectroscopic data (IR, electronic, (1)H and (13)C NMR) along with magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses. Electrical conductance measurement revealed a 1 : 3 electrolytic nature of the complexes. The resulting colored products are monomeric in nature. On the basis of the above studies, three ligands were suggested to be coordinated to each metal atom by thione sulphur and azomethine nitrogen to form low-spin octahedral complexes with ruthenium(III) while forming diamagnetic complexes with rhodium(III). Both ligands and their complexes have been screened for their bactericidal activities and the results indicate that they exhibit a significant activity. PMID:17505530

Sharma, Vinod K; Srivastava, Shipra; Srivastava, Ankita

2007-03-06

285

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

286

Spectroscopic studies of hazardous fuel interactions with soils. Interim report, October 1989-October 1990  

SciTech Connect

This report describes the development and application of techniques for the spectroscopic study of hazardous fuel compounds in soils. The objective is to obtain improved models of bulk pollutant transport through soils. Two approaches have been used for this study: one consists of in-situ measurements of electronic and vibrational interactions via ultraviolet-visible spectroscopy and infrared spectroscopy, respectively; the other incorporates analytical separation techniques to extract contaminants from soils and identify individual reaction products. Initially, montmorillonite clay has been chosen as a prototype soil sample because the structure of this clay is well characterized and spectroscopic results can be readily interpreted. Further simplification has been obtained by exposing the clay samples to individual fuel components rather than mixtures. An interpretation of one clay/fuel system has been accomplished. The plan is to gradually increase the complexity of the samples until typical field conditions can be modeled.

Tipton, T.L.; Stone, D.A.

1993-12-01

287

Sum-frequency spectroscopic studies of surfaces/interfaces and phonons  

NASA Astrophysics Data System (ADS)

In recent decades, sum-frequency generation (SFG) has been demonstrated in numerous cases as a powerful spectroscopic technique. It has a unique feature of being electro-dipole forbidden in media with inversion symmetry. Such a feature leads to the intrinsic surface specificity of SFG. This thesis describes a set of SFG studies on systems which are inaccessible to conventional surface probes employing particles: (1) the buried interfaces between alcohol aqueous solutions and silica, and (2) the highly insulating alpha-quartz(0001) surface. Sum-frequency (SF) results revealed rich information of these systems, allowing the extraction of their microscopic structural information. Besides surface studies, we also revisited the bulk phonon spectra of alpha-quartz and investigated the applicability and advantages of SFG as a more general spectroscopic tool.

Liu, Weitao

288

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

289

[Derivative spectrophotometric and NMR spectroscopic study in pharmaceutical science].  

PubMed

This review starts with an introduction of derivative spectrophotometry followed by a description on the construction of a personal computer-assisted derivative spectrophotometric (DS) system. An acquisition system for inputting digitalized absorption spectra into personal computers and a BASIC program for calculating derivative spectra were developed. Then, applications of the system to drug analyses that are difficult with traditional absorption methods are described. Following this, studies on the interactions of drugs with biological macromolecules by the DS and NMR methods were discussed. An (1)H NMR study elucidated that the small unilamellar vesicle (SUV) has a single membrane made of a phosphatidylcholine bilayer, and that chlorpromazine interacts with both the outer and inner layers. (13)C NMR revealed a reduction of the dissociation constants of phenothiazine drugs due to their interaction with SUV. The partition coefficients of phenothiazine, benzodiazepine and steroid drugs in an SUV-water system and the effects of cholesterol or amino lipids content on these partition coefficients were examined by the DS method. The binding constants of phenothiazine drugs to bovine serum albumin (BSA) and the influence of Na(+), K(+), Cl(-), Br(-), and I(-) on these binding constants were determined by DS. It was found that I(-), Br(-), Cl(-) reduce the binding constants in this order, and that Na(+) and K(+) have no effect. A (19)F NMR study revealed that triflupromazine binds to BSA and human serum albumin in two regions including Site II with different populations, and that a nonsteroidal anti-inflammatory drug, niflumic acid, binds Sites Ia and Ib. PMID:17917421

Kitamura, Keisuke

2007-10-01

290

Fourier transform Raman spectroscopic studies of human and animal skins  

NASA Astrophysics Data System (ADS)

The stratum corneum is the outermost layer of the skin and provides the principal barrier for the ingress of chemicals and environmental toxins into human and animal tissues. However, human skin has several advantages for the administration of therapeutic agents (transdermal drug delivery), but problems occur with the supply, storage, and biohazardous nature of human tissue. Hence, alternative animal tissues have been prepared to model drug diffusion across human skin but the molecular basis for comparison is lacking. Here, FT-Raman spectra of mammalian (human and pig) and reptilian (snake) skins have been obtained and the structural dissimilarities are correlated with drug diffusion studies across the tissues.

Barry, Brian W.; Edwards, Howell G.; Williams, Adrian C.

1994-01-01

291

Multinuclear nuclear magnetic resonance spectroscopic study of cartilage proteoglycans  

SciTech Connect

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

Lerner, L.

1985-01-01

292

Nuclear shapes from spectroscopic studies of fission fragments  

SciTech Connect

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

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

1989-01-01

293

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 × 104 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

294

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

295

IR-spectroscopic study of lewis acid centers on polyzirconiummethylsiloxanes  

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

296

Photodegradation of wood at elevated temperature: infrared spectroscopic study.  

PubMed

The purpose of this investigation was to evaluate the effect of elevated temperature on the photodegradation of solid wood. The work presented here, deals with the changes of infrared spectrum generated by the photodegradation process. Wood samples were irradiated with a mercury vapour lamp. The photodegradation behaviours of conifers and deciduous species were studied at elevated (80 °C) and at ambient (30 °C) temperatures. The infrared data were analysed using the difference spectrum method. The properly calculated difference spectrum gave much more information about the chemical changes than the visual comparison of the absorption spectra measured before and after the irradiation. The results showed considerably greater degradation at 80 °C than at 30 °C. The difference spectra revealed the absorption increase of tree different types of carbonyl groups. Remarkable differences were found between the photodegradation behaviours of softwoods and hardwoods. Poplar belongs anatomically to the hardwoods but its photodegradation properties were between that of hardwoods and softwoods. PMID:23501727

Tolvaj, Laszlo; Molnar, Zsolt; Nemeth, Robert

2013-02-16

297

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.

298

Optical and EPR spectroscopic studies of demetallation of hemin by L-chain apoferritins  

Microsoft Academic Search

Earlier crystallographic and spectroscopic studies had shown that horse spleen apoferritin was capable of removing the metal ion from hemin (Fe(III)-protoporphyrin IX) [G. Précigoux, J. Yariv, B. Gallois, A. Dautant, C. Courseille, B. Langlois d’Estaintot, Acta Cryst. D50 (1994) 739–743; R.R. Crichton, J.A. Soruco, F. Roland, M.A. Michaux, B. Gallois, G. Précigoux, J.-P. Mahy, D. Mansuy, Biochemistry 36 (1997) 15049–15054].

Noëlle Carette; Wilfred Hagen; Luc Bertrand; Natalia de Val; Didier Vertommen; Francine Roland; Louis Hue; Robert R. Crichton

2006-01-01

299

FTIR and circular dichroism spectroscopic study of interaction of 5-fluorouracil with DNA  

Microsoft Academic Search

5-Fluorouracil (5FU) is an anticancer chemotherapeutic drug which exerts cytotoxic effect by inhibiting cellular DNA replication. In the present study, we explore the binding of 5FU with DNA and resulting structural and conformational changes on DNA duplex. UV–visible, Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopic techniques were employed to explore these interactions. A constant concentration of calf thymus

Deepak K. Jangir; Sonika Charak; Ranjana Mehrotra; Suman Kundu

2011-01-01

300

Raman spectroscopic study of ancient South African domestic clay pottery.  

PubMed

The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al2Si2O5(OH)5), illite (KAl4(Si7AlO20)(OH)4), feldspar (K- and NaAlSi3O8), quartz (alpha-SiO2), hematite (alpha-Fe2O3), montmorillonite (Mg3(Si,Al)4(OH)2 x 4.5 5H(2)O[Mg]0.35), and calcium silicate (CaSiO3). Gypsum (CaSO4 x 2H2O) and calcium carbonates (most likely calcite, CaCO3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO(2)) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 degrees C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively. PMID:16839805

Legodi, M A; de Waal, D

2006-07-12

301

Raman spectroscopic study of ancient South African domestic clay pottery  

NASA Astrophysics Data System (ADS)

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

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

2007-01-01

302

Acidic properties of sulfated zirconia: An infrared spectroscopic study  

SciTech Connect

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

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

1995-04-01

303

Spectroscopic studies of laser plasmas for EUV sources  

NASA Astrophysics Data System (ADS)

With the availability of high reflectivity multilayer mirrors and zone plate lenses, the EUV region (5nm - 40nm) of the electromagnetic spectrum is currently being explored for applications of nanoscale printing and imaging. Advances made in this area have consequences for many areas of science. Research for producing a compact, bright EUV source for laboratory use has gained momentum in recent years. For this study, EUV radiation is produced by irradiating target materials using a focused laser beam. Focused laser beam ionizes the target to create a hot, dense, pulsed plasma source, where emission is a result of the relaxation of excited levels. Spectroscopy is used as the main diagnostic to obtain the spectral signature of the plasma. Spectral characteristics are used to deduce the physical state of plasma, thus enabling the tuning of laser irradiance conditions to maximize the needed emission bandwidth. Various target materials are studied, as well as different target geometries, with spectroscopy below 200 nm on pulsed micro-plasmas being a particularly daunting task. Total range spectroscopy from 1 nm to greater than 1 micron is completed for tin-doped spherical droplet plasma source. Reliable plasma diagnostics require both accurate measurements and solid theoretical support in order to interpret the experimental results. Using existing 1D-hydrocode, temperature and density characteristics of the expanding plasma is simulated for any set of experimental conditions. Existing atomic codes written for calculating one-electron radial wavefunctions with LS-coupling scheme via Hartree-Fock method is used in order to gain details of the ion stages, populations, transitions, etc, contributing to the spectral data.

George, Simi A.

304

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

305

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

306

Spectroscopic studies of refractory and dielectric thin films  

SciTech Connect

This work demonstrated the application of the techniques and methodology of surface science to investigate the mechanisms of thin film deposition processes on solid surfaces. The synthesis of boron nitride (BN) thin films was studied using X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). In this model system, diborane (B[sub 2]H[sub 6]), ammonia (NH[sub 3]) and hydrazine (N[sub 2]H[sub 4]) were used as precursors to deposit BN thin films on a clean Ru(0001) surface. The result showed that ammonia reaction with diborane yielded only boron-rich boron nitride overlayers. However, stoichiometric BN films in excess of one monolayer could be produced when hydrazine was substituted for ammonia. The effects of oxygen on boron-rich and stoichiometric boron-nitrogen films were also examined. In the second part of this work, high resolution electron energy loss spectroscopy (HREELS) was used to characterize defect centers in MgO and in lithium-doped MgO thin films. The HREELS results showed that MgO thin films grown on Mo(100) were nearly defect-free at temperatures up to 1100 K. HREELS measurements indicated that annealings to higher temperatures induced F-type defect centers in the MgO films. The formation of [Li[sup +]O[sup [minus

Truong, C.M.

1993-01-01

307

Studies on selected polymeric materials using the photoacoustic spectroscopic technique  

NASA Astrophysics Data System (ADS)

Polymethylmethacrylate—graft—polybisphenol—A-carbonate (PMMA-G-PC) with 50% grafting is synthesized. The graft co-polymerization of methylmethacrylate (0.036 mol · lit-1) onto polybisphenol—A-carbonate (0.5 g) in the presence of a redox couple formed from potassium persulphate (40 mol · lit-1) and thio-urea (30 mmol · lit-1) in aqueous nitric acid (0.18 M, 100 ml) in air at (45±2) °C for 3.0 h. Condensation of (PMMA-G-PC) with N- [p-(carboxyl phenyl amino acetic acid)] hydrazide (PCPH) affords polybisphenol-A-carbonate-graft-polymethylmethacrylate hydrazide (PCGH). The photoacoustic (PA) spectra of (PCGH) are recorded in a wavelength range from 200 nm to 800 nm at a modulation frequency of 22 Hz, and compared with those of pure polybisphenol-A-carbonate (PC), (PMMA-G-PC) and (PCPH). In the present work, a non-destructive and non-contact analytical method, namely the photoacoustic technique, is successfully implemented for optical and thermal characterization of selected polymeric materials. The indigenous PA spectrometer used in the present study consists of a 300-W xenon arc lamp, a lock-in amplifier, a chopper, a (1/8)-m monochromator controlled by computer and a home-made PA cell.

Hukum, Singh

2011-06-01

308

Rotational spectroscopic study of carbonyl sulfide solvated with hydrogen molecules.  

PubMed

Rotational spectra of small-sized (H(2))(N)-OCS clusters with N = 2-7 were measured using a pulsed-jet Fourier transform microwave spectrometer. These include spectra of pure (para-H(2))(N)-OCS clusters, pure (ortho-H(2))(N)-OCS clusters, and mixed ortho-H(2) and para-H(2) containing clusters. The rotational lines of ortho-H(2) molecules containing clusters show proton spin-proton spin hyperfine structure, and the pattern evolves as the number of ortho-H(2) molecules in the cluster increases. Various isotopologues of the clusters were investigated, including those with O(13)CS, OC(33)S, OC(34)S, and O(13)C(34)S. Nuclear quadrupole hyperfine structures of rotational transitions were observed for (33)S (nuclear spin quantum number I = 3/2) containing isotopologues. The (33)S nuclear quadrupole coupling constants are compared to the corresponding constant of the OCS monomer and those of the He(N)-OCS clusters. The assignment of the number of solvating hydrogen molecules N is supported by the analyses of the proton spin-proton spin hyperfine structures of the mixed clusters, the dependence of line intensities on sample conditions (pressure and concentrations), and the agreement of the (para-H(2))(N)-OCS and (ortho-H(2))(N)-OCS rotational constants with those from a previous infrared study [J. Tang and A. R. W. McKellar, J. Chem. Phys. 121, 3087 (2004)]. PMID:19045151

Michaud, Julie M; Jäger, Wolfgang

2008-10-14

309

Raman spectroscopic study of G—A mismatches  

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

310

Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants  

SciTech Connect

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

Gindt, Y.M.

1993-04-01

311

Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants  

SciTech Connect

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

Gindt, Y.M.

1993-04-01

312

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

PubMed

The interactions between gemcitabine hydrochloride (GEM) and bovine serum albumin (BSA) or human serum albumin (HSA) have been studied by spectroscopic techniques. By the analysis of fluorescence spectrum and fluorescence intensity, it was observed that the GEM has a strong ability to quench the intrinsic fluorescence of both BSA and HSA through a static quenching procedure. The association constants of GEM with BSA and HSA were determined at different temperatures based on fluorescence quenching results. The negative DeltaH degrees and positive DeltaS degrees values in case of GEM-BSA and GEM-HSA complexes showed that both hydrogen bonds and hydrophobic interactions play a role in the binding of GEM to BSA or HSA. Experimental results showed that the binding of GEM to BSA or HSA induced conformational changes in BSA and HSA. From the quantitative analysis data of CD spectra, the alpha-helix of 57.58% and 34.82% in free BSA and free HSA decreased to 40.82% and 29.84% in BSA-GEM and HSA-GEM complexes, respectively, and hence confirmed that the secondary structure of protein was altered by GEM. The interactions of BSA and HSA with GEM were also confirmed by UV absorption spectra. The distance, r, between donor (BSA or HSA) and acceptor (GEM) was obtained according to the Förster's theory of non-radiation energy transfer. The effects of common ions on the binding constants of both BSA-GEM and HSA-GEM complexes were also investigated. PMID:16413740

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

2006-01-18

313

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 67 at. %) bulk glasses in the UV-vis-NIR (near infrared) spectral region for photon energies from 0.54 to 4.13 eV (photon wavelengths from 2300 to 300 nm). 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+/-0.02 eV for As33S67 to 1.75+/-0.01 eV for As33Se67 and linear increase in refractive index nTL in the NIR spectral region, e.g., at 0.80 eV 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=33.5 at. % 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

314

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

315

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

NASA Astrophysics Data System (ADS)

The structure of compound has also been examined cyrstallographically. It crystallizes in the monoclinic space group P21/ c with a = 7.673(1), b = 16.251(2), c = 10.874(1) Å, ? = 110.42(1)°, V = 1270.7(3) Å3, D x = 1.418 g cm-3, R 1 = 0.0349 and wR 2 = 0.0935 [ I > 2?( 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, 1H NMR, 13C NMR and UV-Visible spectroscopic techniques.

Ozay, H.; Yildiz, M.; Unver, H.; Kiraz, A.

2013-01-01

316

[Spectroscopic and dynamical studies of highly energized small polyatomic molecules]. [Stimulated emission pumping  

SciTech Connect

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

Not Available

1992-01-01

317

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

318

IR and VUV spectroscopic studies at low temperature for the interpretation of Cassini data  

NASA Astrophysics Data System (ADS)

Titan's atmosphere mainly made of nitrogen and methane is rich in organic molecules. Hydrocarbons are formed from the photolytic dissociation of CH4 and nitriles are created by dissociation of N2 followed by reactions with hydrocarbons. In order to understand the physicochemical mechanisms responsible for the evolution of Titan's atmosphere, photochemical models are built. The latter need constrains for vertical profiles of organic compounds from the high thermosphere down to the low stratosphere as well as photodissociation rates. Those profiles over the entire atmosphere can be retrieved from Cassini observations, in particular by limb sounding, coupling infrared and ultraviolet spectroscopy. However, in order to interpret those data obtained by the ultraviolet (UVIS) and infrared (CIRS) spectrometers on board Cassini's spacecraft, precise spectroscopic parameters and their dependence on temperature are needed. We will review the current knowledge in this field of planetary spectroscopy and point out the lack of spectroscopic parameters of already detected species, especially for radiative transfer calculations at low temperature. We will also underline needs for the determination of spectra of undetected molecules but expected to be present in Titan's atmosphere according to laboratory simulations. Infrared and Ultraviolet spectroscopic data recovered by our team for some compounds of interest for Titan's atmosphere will be presented. These studies concern in particular polyynes and cyanopolyynes, compounds of primary interest since they could link the gaseous and the solid phase. We will show how temperature can influence VUV absorption coefficients and the implications on the interpretation of UVIS observations. We will also show that low temperature laboratory infrared spectra can help for the determination of spectroscopic parameters for molecules with low lying bending modes and thus help the interpretation of CIRS measurements.

Yves, Benilan; Ferradaz, Thomas; Guillemin, Jean-Claude; Fray, Nicolas; Gazeau, Marie-Claire; Jolly, Antoine; Raulin, Francois; Schwell, Martin

319

FTIR and circular dichroism spectroscopic study of interaction of 5-fluorouracil with DNA.  

PubMed

5-Fluorouracil (5FU) is an anticancer chemotherapeutic drug which exerts cytotoxic effect by inhibiting cellular DNA replication. In the present study, we explore the binding of 5FU with DNA and resulting structural and conformational changes on DNA duplex. UV-visible, Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopic techniques were employed to explore these interactions. A constant concentration of calf thymus DNA was incubated with varying concentrations of 5FU. UV-visible and FTIR spectroscopic results revealed that intercalation is the primary mode of interaction between 5FU and nitrogenous bases of the nucleic acid. The binding constant was found to be 9.7×10(4); which is indicative of moderate type of interaction between 5FU and DNA duplex. It was also observed that 5FU intercalates slightly more between AT base pairs compared to GC pairs. FTIR and circular dichroism spectroscopic results revealed that 5FU disturbs native B-conformation of DNA though, DNA remains in its B conformation even at higher concentrations of 5FU. PMID:21940176

Jangir, Deepak K; Charak, Sonika; Mehrotra, Ranjana; Kundu, Suman

2011-08-18

320

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

NASA Astrophysics Data System (ADS)

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

Adeniyi, Adebayo A.; Ajibade, Peter A.

2013-11-01

321

Optical and other spectroscopic studies of lead, zinc bismuth borate glasses doped with CuO  

NASA Astrophysics Data System (ADS)

10MO·20Bi2O3·(70-x)B2O3·xCuO [M=Pb, Zn] with x=0, 0.4 and 0.8 (wt%) glasses were synthesized by the melt-quenching technique and were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Physical parameters, like density, and spectroscopic studies (optical absorption, EPR, FTIR and photoluminescence) were used to understand the role of modifier oxide and CuO in the glass matrix. A red shift of the absorption band corresponds to 2B1g?2B2g transition of Cu2+ ions from P2 to Z4 samples and the increase of hyperfine splitting factor (A?) from P2 to Z2 shows that with the integration of PbO by ZnO the electron density around copper ion is increased. It is also supported by the gradual increase in theoretical optical basicity values of ZnO mixed glasses, as compared to that of PbO mixed glass matrix. Reduced bismuth radicals are found in undoped and 0.4% CuO doped glasses of both the series. Analysis of the absorption and emission studies indicates that the concentration of luminescence centers of bismuth ions (Bi3+ ions in UV region) is decreased by the integration of ZnO as well as by increasing the dopant concentration. In lead series PbO4 and BiO3 units are increased from P2 to P4 and in zinc series BiO3 units are decreased from Z0 to Z4. The conductivity of the glass matrices is increased in both the series with the dopant of CuO.

Rajyasree, Ch.; Vinaya Teja, P. Michael; Murthy, K. V. R.; Krishna Rao, D.

2011-12-01

322

New Orbital Parameters and Radial Velocity Curve Analysis of Spectroscopic Binary Stars  

NASA Astrophysics Data System (ADS)

We use a Probabilistic Neural Network (PNN) technique to derive the orbital parameters of spectroscopic binary stars. Using measured radial velocity data of five double-lined spectroscopic binary systems (i.e., EQ Tau, V376 And, V776 Cas, V2377 Oph and EE Cet), we find the corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with those obtained by other groups via more traditional methods.

Ghaderi, Kamal; Pirkhedri, Ali; Rostami, Touba; Khodamoradi, Salem; Fatahi, Hedayat

2012-02-01

323

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

324

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

325

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

326

Spectroscopic and structural study of proton and halide ion cooperative binding to gfp.  

PubMed

This study reports the influence of halogens on fluorescence properties of the Aequorea victoria Green Fluorescent Protein variant S65T/T203Y (E(2)GFP). Halide binding forms a specific nonfluorescent complex generating a substantial drop of the fluorescence via static quenching. Spectroscopic analysis under different solution conditions reveals high halogen affinity, which is strongly dependent on the pH. This evidences the presence in E(2)GFP of interacting binding sites for halide ions and for protons. Thermodynamic link and cooperative interaction are assessed demonstrating that binding of one halide ion is associated with the binding of one proton in a cooperative fashion with the formation, in the pH range 4.5-10, of a single fully protonated E(2)GFP.halogen complex. To resolve the structural determinants of E(2)GFP sensitivity to halogens, high-resolution crystallographic structures were obtained for the halide-free and I(-), Br(-), and Cl(-) bound E(2)GFP. Remarkably the first high-resolution (1.4 A) crystallographic structure of a chloride-bound GFP is reported. The chloride ion occupies a specific and unique binding pocket in direct contact (3.4 A) with the chromophore imidazolidinone aromatic ring. Unanticipated flexibility, strongly modulated by halide ion interactions, is observed in the region surrounding the chromophore. Furthermore molecular dynamics simulations identified E222 residue (along with the chromophore Y66 residue) being in the protonated state when E(2)GFP.halogen complex is formed. The impact of these results on high-sensitivity biosensor design will be discussed. PMID:17434942

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

2007-04-13

327

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

328

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

NASA Astrophysics Data System (ADS)

Aims: We present basic atmospheric parameters (Teff, log g, vt, and [Fe/H]) as well as luminosities, masses, radii, and absolute radial velocities for 348 stars, presumably giants, from the ~1000 star sample observed within the Penn State-Toru? Centre for Astronomy Planet Search with the High Resolution Spectrograph of the 9.2 m Hobby-Eberly Telescope. The stellar parameters (luminosities, masses, radii) are key to properly interpreting newly discovered low-mass companions, while a systematic study of the complete sample will create a basis for future statistical considerations concerning the appearance of low-mass companions around evolved low- and intermediate-mass stars. Methods: The atmospheric parameters were derived using a strictly spectroscopic method based on the LTE analysis of equivalent widths of Fe I and Fe II lines. With existing photometric data and the Hipparcos parallaxes, we estimated stellar masses and ages via evolutionary tracks fitting. The stellar radii were calculated from either estimated masses and the spectroscopic log g or from the spectroscopic Teff and estimated luminosities. The absolute radial velocities were obtained by cross-correlating spectra with a numerical template. Results: We completed the spectroscopic analysis for 332 stars, 327 of which were found to be giants. A simplified analysis was applied to the remaining 16 stars, which had incomplete data. The results show that our sample is composed of stars with effective temperatures ranging from 4055 K to 6239 K, with log g between 1.39 and 4.78 (5 dwarfs were identified). The estimated luminosities are between log L/L? = -1.0 and 3 and lead to masses ranging from 0.6 to 3.4 M?. Only 63 stars with masses larger than 2 M? were found. The radii of our stars range from 0.6 to 52 R? with the vast majority between 9-11 R?. The stars in our sample are generally less metal-abundant than the Sun with median [Fe/H] = -0.15. The estimated uncertainties in the atmospheric parameters were found to be comparable to those reached in other studies. However, due to lack of precise parallaxes, the stellar luminosities and, in turn, the masses are far less precise, within 0.2 M? in best cases and 0.3 M? on average. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.Tables 1 and 5 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/547/A91

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

2012-11-01

329

A systematic spectroscopic study of eight hydrous ferric sulfates relevant to Mars  

NASA Astrophysics Data System (ADS)

Ferric sulfates were observed on Mars during orbital remote sensing and surface explorations. These observations have stimulated our systematic experimental investigation on the formative conditions, stability fields, phase boundaries, and phase transition pathways of these important minerals. We report here the results from the first step of this project: eight synthesized anhydrous and hydrous crystalline ferric sulfates and their structural characters reflected through spectroscopic studies. A few phenomena observed during the 150 sets of on-going experiments for stability field study are also reported, which reveal the structural distortions that can happen under environmental conditions relevant to Mars.

Ling, Z. C.; Wang, Alian

2010-10-01

330

Spectroscopic study of sub-barrier quasi-elastic nuclear reactions  

SciTech Connect

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

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

1988-01-01

331

High Sensitivity and Resolution Decimetric Spectroscope: Preliminary Analysis of Solar Bursts.  

National Technical Information Service (NTIS)

High sensitivity radio spectroscope in conjunction with a 9 meter diameter polar mounted antenna has been put into regular operation since December 1990. Spectroscope operates over band of 1600 +/- 100 MHz with high time (20-100 ms) and frequency (0.3-3 M...

F. C. R. Fernandes

1992-01-01

332

Variable-temperature Fourier transform infrared spectroscopic investigations of poly(3-hydroxyalkanoates) and perturbation-correlation moving-window two-dimensional correlation analysis. Part I: Study of non-annealed and annealed poly(3-hydroxybutyrate) homopolymer.  

PubMed

Generalized two-dimensional correlation spectroscopy (2DCOS) and perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy were applied to explore the melting behavior of non-annealed and annealed poly(3-hydroxybutyrate) (PHB) homopolymer as studied by variable-temperature Fourier transform infrared (FT-IR) spectroscopy. The absorption band of the C=O stretching vibration was employed to investigate the structural changes during the heating process (30-200 degrees C). Non-annealed PHB showed a recrystallization process in the temperature range 30-120 degrees C. In the asynchronous 2D correlation spectrum we clearly captured the existence of two components in the crystallinity-sensitive wing of the C=O stretching mode: a well-ordered crystalline state at lower wavenumbers (1718 cm(-1)) and a less ordered crystalline state at higher wavenumbers (1724 cm(-1)). These crystallinity-sensitive bands at 1718 and 1724 cm(-1), which are not readily detectable in the one-dimensional (1D) FT-IR spectra, share asynchronous cross-peaks with bands at around 1737 and 1747 cm(-1) assignable to the C=O stretching absorptions due to the amorphous components. In the case of the melting process of non-annealed PHB in the temperature range 120-200 degrees C, it is helpful to use the PCMW2D correlation analysis, which indicates the recrystallization between 40 and 110 degrees C by the shift of the C=O stretching band from 1726 cm(-1) to 1722 cm(-1) and the sharp change to the broad amorphous C=O stretching absorption at 1747 cm(-1) at the melting temperature of PHB around 190 degrees C. For an annealed sample of PHB only the melting behavior was observed in the PCMW2D correlation analysis by the sharp transition from the crystalline to the amorphous C=O stretching band. PMID:19796485

Unger, Miriam; Morita, Shigeaki; Sato, Harumi; Ozaki, Yukihiro; Siesler, Heinz W

2009-09-01

333

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

334

Study of the complexation of different methacrylates with cyclodextrins employing a combination of electrophoretic, chromatographic, and NMR-spectroscopic methods.  

PubMed

The present study describes the application of capillary electromigration techniques; CEC and micellar EKC (MEKC), and the application of spectroscopic methods; 1H NMR and 1H NOESY spectroscopy to investigate interactions between CDs (alpha-CD, statistically methylated beta-CD, hydroxypropyl-beta-CD, and 2-hydroxypropyl-gamma-CD) and different methacrylates (adamantyl, isobornyl, cyclohexyl, and phenyl methacrylate). It is shown that these methods complement each other. While CD-mediated MEKC is a rapid screening technique for comparing complex stabilities in aqueous media, 1H NMR chemical shift analysis provides quantitative data for very strong methacrylate-CD complexes and CD-mediated CEC provides quantitative data for complexes with lower complex forming constants. CD-mediated MEKC did not prove to be suitable for the calculation of complex forming constants. Reasons are discussed. 1H NOESY spectra were used to study spatial relationships between host and guest atoms. PMID:17461118

Al-Rimawi, Fuad; Pyell, Ute

2007-03-01

335

Energy dispersive x-ray spectroscopic analysis in a microscopic area of a grain in YBCO ceramic superconductor  

Microsoft Academic Search

In the YBCO ceramic superconductor family, there are many different phases such as Y-124, Y-125, Y-145 and Y-111. Here, we obtain phase information in a microscopic area using EDX, i.e. energy dispersive X-ray spectroscopic analysis. EDX analysis is a relatively new method for determining the atomic percentage of a specimen. Within a microscopic region, nearly 10 x 10 micron in

J. C. L. Chow; P. C. W. Fung

1994-01-01

336

Synthesis and Raman spectroscopic studies of NaZr2(PO4)3  

NASA Astrophysics Data System (ADS)

Sodium Zirconium Phosphate (NaZr2(PO4)3), a low thermal expansion material is synthesized by aqueous sol gel method. Raman spectroscopic studies are carried out as a function of temperature from 80 K to 860 K. The modes at 72 and 423 cm-1 exhibit a positive temperature coefficient which points to their negative role in thermal expansion. These modes are due to the translational motion of Na atoms and rotational motion of PO4 ions respectively, and it is conceivable that they contribute to negative thermal expansion in this material.

Kamali, K.; Ravindran, T. R.; Sridharan, V.; Nithya, R.

2012-06-01

337

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

338

L-Valine and L-Proline--solid-state IR-LD spectroscopic study.  

PubMed

Spectral investigation including IR-characteristic bands assignment of the amino acids zwitterions (L)-Valine ((L)-Val) and (L)-Proline ((L)-Pro) was carried out by linear-dichroic infrared (IR-LD) spectroscopy of oriented solid sample as a nematic liquid crystal suspension. The obtained experimental IR-LD results (transition moment directions) were compared with known crystal X-ray data for molecules orientation in the unit cells of the studied compounds, confirming the applicability of the used spectral method for structural determination. The influence of the protonation on the IR-spectroscopic patterns of the both amino acids is discussed. PMID:20236087

Chapkanov, A G; Zareva, S Y

2010-03-01

339

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

SciTech Connect

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

Bowers, J.L.; Oldfield, E.

1988-07-12

340

Spectroscopic studies of amino acid ionic liquid-supported Schiff bases.  

PubMed

Amino acid ionic liquid-supported Schiff bases, derivatives of salicylaldehyde and various amino acids (L-threonine, L-valine, L-leucine, L-isoleucine and L-histidine) have been investigated by means of various spectroscopic techniques (NMR, UV-Vis, IR, MS) and deuterium isotope effects on ¹³C-NMR chemical shifts. The results have shown that in all studied amino acid ionic liquid-supported Schiff bases (except the L-histidine derivative) a proton transfer equilibrium exists and the presence of the COO? group stabilizes the proton transferred NH-form. PMID:23629755

Ossowicz, Paula; Janus, Ewa; Schroeder, Grzegorz; Rozwadowski, Zbigniew

2013-04-29

341

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

342

Analysis of Fiber-Optic Spectroscopic Measurements on the Compact Toroid Injection Experiment (CTIX)  

NASA Astrophysics Data System (ADS)

Spectroscopic analysis of accelerated plasmas, such as those created in CTIX, can be used to determine plasma impurity content, density and temperature via line ratios, and velocity via asymmetric Doppler shifting. Optical fibers have been installed at various locations around the CTIX plasma and connected to a visible spectrometer. The fibers can be distributed by axially, radially or by orientation. An intensified charge-coupled camera is used to view the spectrometer output with ˜1.0 å resolution. By vertically stacking the fibers, multiple viewing locations can be monitored simultaneously. To interpret the raw camera data, new software has been developed to process the camera image as a lattice where rows correspond to fiber positions, and columns to wavelengths. By simultaneously acquiring multiple fiber positions, errors arising from shot-to-shot plasma variations are eliminated and the overall amount of spectral data per plasma shot is increased. Specifics on data processing and analysis techniques as well as preliminary results obtained on CTIX will be presented.

Moser, Daniel; Horton, Robert; Hwang, David; Klauser, Ruth

2010-11-01

343

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

SciTech Connect

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

Pizarro, Shelly A.

2000-05-12

344

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

345

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

NASA Astrophysics Data System (ADS)

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

Zhang, Xulong

346

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

NASA Astrophysics Data System (ADS)

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

Lau, Yuen Agnes

347

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

348

An efficient MR phosphorous spectroscopic localization technique for studying ischemic heart.  

PubMed

To obtain the spatially resolved (31)P spectroscopic image from myocardium during an acute myocardium ischemia at a high signal-to-noise ratio (SNR) in a very limited time window, we have exploited the spatial variation of the radiofrequency (RF) field produced by a single loop transmit/receive (TR) RF coil along its axis for spatial discrimination. By incrementally lengthening the duration of a square RF excitation pulse, the positional information can be systematically encoded as harmonics of various orders in MR signal. In the in vivo open-chest animal experiment, this RF coil was surgically sutured onto the epicardial surface of the left ventricular (LV) wall over the region perfused by the left anterior descending coronary artery. Using only 17 encoding steps, we have obtained one-dimensional (31)P spectroscopic images from both a multiple-layer phosphor phantom and an in vivo LV myocardium. In the animal study, the cardiac gating is used with respiratory synchronization. The MR data were only collected during the end diastole phase of the cardiac cycle (cardiac and respiratory synchronized) with an effective sequence repetition time (TR) of 6 seconds (to ensure the complete relaxation of the phosphorous magnetization). The total acquisition time for a complete experiment is about 10 minutes. Prior to the CSI reconstruction process, the raw data matrix was zero-filled in the spatial dimension. The spatially resolved metabolite map exhibited all the metabolite peaks including creatine phosphate and adenosine triphosphate. At the layer of endocardium, two peaks corresponding to 2, 3-diphosphoglycerate, which is contained in the erythrocytes, were clearly seen in the LV wall. Also, the method allows compensation in both volume and coil sensitivity variations for the resulting spectra. All results have demonstrated that it is an efficient nuclear magnetic resonance method capable of obtaining high-quality (31)P spectroscopic images with both excellent spatial localization and SNR in the research of cardiac ischemia. J. Magn. Reson. Imaging 1999;10:892-898. PMID:10548804

Liu, H; Zhang, J

1999-11-01

349

IR and UV spectroscopic studies at low temperature: C2N2  

NASA Astrophysics Data System (ADS)

Titan's atmosphere is mainly made of nitrogen and methane and is furthermore very rich in organic molecules. Hydrocarbons are formed by the photodissociation of CH4 and nitriles are created by dissociation of N2 followed by reactions with hydrocarbons. In order to understand the physicochemical mechanisms responsible for the evolution of Titan's atmosphere, photochemical models are built. The latter needs constraints for the determination of vertical profiles of organic compounds, from the higher thermosphere down to the lower stratosphere. They also need wavelength dependant photodissociation rates as input parameters. Vertical profiles can be retrieved from Cassini observations along the entire atmosphere, in particular by limb sounding using Cassini's UVIS and CIRS spectrometers. However, in order to interpret data obtained by these instruments, precise spectroscopic parameters and their dependence on temperature are needed. We will review the current knowledge in this field of planetary spectroscopy and point out the lack of spectroscopic parameters of already detected species. These parameters are especially needed for radiative transfer calculations at low temperatures. We will focus our talk on the Cyanogen molecule (C2N2) which has been observed in Titan's atmosphere in the FIR domain, around 230 cm-1. We will present the latest spectroscopic studies we have performed on this molecule which cover the entire spectrum from the mid- infrared to the vacuum ultraviolet spectral region. Integrated band intensities have been determined for all bands in the infrared. In the ultraviolet domain, we have determined absolute cross sections from 350 down to 80 nm covering six orders of magnitude for the absorption coefficient. We will also show how temperature can influence VUV absorption coefficients. The corresponding implications of temperature dependant absorption data on the interpretation of UVIS observations will be discussed.

Benilan, Y.; Arzoumanian, E.; Es-Sebbar, Et.; Ferradaz, T.; Fray, N.; Jolly, A.; Gazeau, M.-C.; Schwell, M.

2008-09-01

350

Photometric and spectroscopic study of the S0 galaxy, NGC 1266  

NASA Astrophysics Data System (ADS)

We present the results from a photometric and spectroscopic study of the S0 galaxy, NGC 1266, in the optical wavelengths. This project was carried out as part of the IGO observational training school, held during 20 December, 2010 to 15 January, 2011, at IUCAA (Pune). Surface photometry was performed in the BVR wide band and H-alpha narrow band filters. We used ellipse fitting to the isophotes, to measure the surface-brightness profile, the radial variation of position angle, ellipticity, and the B4 (boxyness/diskyness) parameter. We created colour maps and H-alpha emission line maps to identify the spatial distribution of dust features and ionized gas. We report the identification of extended cone of ionized gas outflow in the central 2 kiloparsec region of NGC 1266. Follow-up spectroscopy shows that the narrow-band emission is dominated by the [N II] emission, which is stronger than H-alpha emission. We detect outflow velocity of approximately 500 km s^{-1} from the wavelength shifts of the emission lines. Our results from the spectroscopic study include emission line identification, flux measurements of the emission lines, and physical parameters of the ionized gas.

Sahu, Sheetal Kumar

351

Reproducibility Study of Whole-Brain 1H Spectroscopic Imaging with Automated Quantification  

PubMed Central

A reproducibility study of proton magnetic resonance spectroscopic imaging (1H-MRSI) of the human brain was conducted to evaluate the reliability of an automated 3D in vivo spectroscopic imaging acquisition and associated quantification algorithm. A PRESS-based pulse sequence was implemented using dualband spectral-spatial RF pulses designed to fully excite the singlet resonances of choline (Cho), creatine (Cre) and N-acetyl aspartate (NAA) while simultaneously suppressing water and lipids. 1% of the water signal was left to be used as a reference signal for robust data processing, and additional lipid suppression was obtained using adiabatic inversion recovery. Spiral k-space trajectories were used for fast spectral and spatial encoding yielding high-quality spectra from 1 cc voxels throughout the brain with a 13 minute acquisition time. Data were acquired with an 8-channel phased-array coil and optimal SNR for the combined signals was achieved using a weighting based on the residual water signal. Automated quantification of the spectrum of each voxel was performed using LCModel. The complete study consisted of 8 healthy adult subjects to assess inter-subject variations and two subjects scanned six times each to assess intra-subject variations. The results demonstrate that reproducible whole-brain 1H-MRSI data can be robustly obtained with the proposed methods.

Kim, Dong-Hyun; Mayer, Dirk; Sullivan, Edith V.; Pfefferbaum, Adolf; Spielman, Daniel M.

2008-01-01

352

Reproducibility study of whole-brain 1H spectroscopic imaging with automated quantification.  

PubMed

A reproducibility study of proton MR spectroscopic imaging ((1)H-MRSI) of the human brain was conducted to evaluate the reliability of an automated 3D in vivo spectroscopic imaging acquisition and associated quantification algorithm. A PRESS-based pulse sequence was implemented using dualband spectral-spatial RF pulses designed to fully excite the singlet resonances of choline (Cho), creatine (Cre), and N-acetyl aspartate (NAA) while simultaneously suppressing water and lipids; 1% of the water signal was left to be used as a reference signal for robust data processing, and additional lipid suppression was obtained using adiabatic inversion recovery. Spiral k-space trajectories were used for fast spectral and spatial encoding yielding high-quality spectra from 1 cc voxels throughout the brain with a 13-min acquisition time. Data were acquired with an 8-channel phased-array coil and optimal signal-to-noise ratio (SNR) for the combined signals was achieved using a weighting based on the residual water signal. Automated quantification of the spectrum of each voxel was performed using LCModel. The complete study consisted of eight healthy adult subjects to assess intersubject variations and two subjects scanned six times each to assess intrasubject variations. The results demonstrate that reproducible whole-brain (1)H-MRSI data can be robustly obtained with the proposed methods. PMID:18727040

Gu, Meng; Kim, Dong-Hyun; Mayer, Dirk; Sullivan, Edith V; Pfefferbaum, Adolf; Spielman, Daniel M

2008-09-01

353

Prosthetic implant associated sarcomas: a case report emphasizing surface evaluation and spectroscopic trace metal analysis.  

PubMed

Advances with implantation of synthetic biomaterials in the setting of orthopedic surgery have clearly resulted in improvements in patient outcomes. However, all implants have been shown to have associated risks. For example, ionic and particulate debris from implants have been shown to engage in biological interactions with the native tissue, and have been associated with a wide range of metabolic, bacteriologic, immunologic, and oncogenic effects. The propensity of synthetic biomaterials to undergo degradation, producing an inflammatory reaction or other sequelae, has been well recognized. The use of porous implants, which allow for a greater interface area between native tissue and the prosthesis, may magnify the interaction between biologically active tissue and synthetic devices in some situations, giving rise to new and intriguing issues concerning biocorrosion and biocompatibility. In this article, we report the case of a high-grade conventional osteosarcoma occurring at the site of a modular porous-surfaced titanium and cobalt alloy total hip prosthesis 3 years after device implantation. Detailed spectroscopic trace metal analysis was performed and elevated levels of both vanadium and chromium, but not aluminum, nickel, or titanium were identified in the tumor. PMID:12616473

Adams, Julie E; Jaffe, Kenneth A; Lemons, Jack E; Siegal, Gene P

2003-02-01

354

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

355

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

356

Spectroscopic and chromatographic analysis of oil from an oil shale flash pyrolysis unit  

Microsoft Academic Search

In this investigation, spectroscopic (FT-IR, UV–Vis, 1H NMR) and chromatographic (GC) techniques were used to analyze two Jordanian shale oils, Sultani and El-Lajjun. The oils were extracted at different pyrolysis temperatures (400–500 °C) using a fluidized bed reactor. The spectroscopic and chromatographic analyses show that the variation of pyrolysis temperature has no significant effect on the composition of the produced

Yahya H Khraisha; Nabih A Irqsousi; Ihsan M Shabib

2003-01-01

357

Raman spectroscopic study of base catalyzed di- and trimerization of malononitrile in ionic liquids and water  

NASA Astrophysics Data System (ADS)

Multivariate Curve Resolution (MCR) and Two-Dimensional Correlation Spectroscopy (2DCoS) have been employed to analyze the Raman spectra recorded from the reaction of malononitrile with KOH carried out in the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate and water. In both cases the carbanion, which is formed by deprotonation of malononitrile, could be detected spectroscopically. When using the ionic liquid as solvent formation of the dimer was observed, whereas in aqueous solution a trimer was formed by a subsequent Michael addition. Based on the component spectra and concentration profiles obtained from MCR analysis the reaction intermediates as well as products could be identified. 2DCoS was very helpful in corroborating these results.

López-Pastor, Mercedes; Domínguez-Vidal, Ana; Ayora-Cañada, Maria José; Valcárcel, Miguel; Lendl, Bernhard

2006-11-01

358

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

NASA Astrophysics Data System (ADS)

( 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, 1H NMR, 13C 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) Å, b = 13.726(2) Å, c = 27.858(4) Å, V = 2756.0(1) Å 3, Dc = 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.

Ünver, Hüseyin; Y?ld?z, Mustafa; Özay, Hava; Durlu, Tahsin Nuri

2009-12-01

359

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

NASA Astrophysics Data System (ADS)

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 spectrometer. A combination of impurity pellet injection and visible bremsstrahlung is an active tool for determination of the diffusion coefficient D and convective velocity V. Using this tool the spatial structures of D and V are obtained and discussed with a neoclassical effect. On the other hand, the spectroscopic method for edge diagnostics is considerably different from the tokamak case because of the existence of a thick ergodic layer in addition to the x-points necessarily included into the diagnostic chord view. In order to break this negative situation, Zeeman and polarization spectroscopy are adopted to LHD edge plasmas. As a result, 2-dimensional emission contours of HeI and H? are successfully obtained. Laser absorption spectroscopy is tried to measure hydrogen neutrals directly. Radial profiles of edge impurities are also measured with a mirror-assembled 3 m VUV spectrometer. Recent results of and progress in LHD spectroscopy are briefly reviewed.

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

2006-01-01

360

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

PubMed

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

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

2012-11-30

361

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

362

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

363

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

SciTech Connect

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

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

2010-10-07

364

Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. Master's thesis  

Microsoft Academic Search

Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. The M0006 semiconductor samples were placed into a 28.5 degree inclination, 480 km altitude, near-circular orbit aboard the Long Duration Exposure Facility satellite and exposed to direct space environment for a period of 11 months, and were shielded by 0.313 inches of aluminum

Shaffer

1990-01-01

365

Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques  

Microsoft Academic Search

Analysis of space radiation effects in gallium arsenide and cadmium selenide semiconductor samples using luminescence spectroscopic techniques. The M0006 semiconductor samples were placed into a 28.5 degree inclination, 480 km altitude, near-circular orbit aboard the Long Duration Exposure Facility satellite and exposed to direct space environment for a period of 11 months, and were shielded by 0.313 inches of aluminum

Brad L. Shaffer

1990-01-01

366

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

367

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

SciTech Connect

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

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

1988-05-05

368

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

369

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

2013-06-11

370

Un sensore CCD bidimensionale veloce per analisi spettroscopiche su plasma. (Fast two-dimensional CCD sensor for spectroscopic analysis of plasma).  

National Technical Information Service (NTIS)

Spectroscopic diagnostics of fast evolving events, like arc or spark discharges, requires the analysis of the light emitted by the plasma with simultaneous spectral, spatial and time resolution. The first two requirements could be fulfilled by imaging the...

U. Perini E. Paganini A. Bargigia G. Tondello

1990-01-01

371

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

NASA Astrophysics Data System (ADS)

ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H 2O 2 pre-treatment induced ohmic to rectifying contact conversion on Au/ n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure.

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

2008-10-01

372

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

PubMed

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

Lenci, F; Ghetti, F

1989-02-01

373

Development of Laser Spectroscopic Techniques and Their Application to the Study of Self-Organizing Molecular Assemblies.  

NASA Astrophysics Data System (ADS)

Laser spectroscopic techniques have been developed and adapted to computer based data gathering, reduction and analysis. The systems implemented are a laser flash photolysis and transient dichroism spectrometer, a single photon counting spectrometer for determination of fluorescence lifetimes and time-resolved fluorescence polarization anisotropy, and a light scattering system for both static and dynamic measurements. These techniques have been concerted to study self-organizing molecular assemblies, particularly surfactant vesicles. Quaternary ammonium surfactant monomers with polymerizable styrene moieties on the headgroup have been sonicated into unilamellar vesicles and these in turn have been photopolymerized by both steady state and pulsed laser irradiation. The detailed kinetics of photopolymerization have been determined and a model developed which permits, in conjunction with the laser spectroscopic data, the characterization of the process in terms of average polymer chain length, quantum efficiency of free radical formation, free radical lifetime, and a characteristic rate parameter. Subsequent to characterizing and modelling the photopolymerization process the consequences of it on vesicle surface properties have been investigated with molecular probes. Strong evidence has been obtained that indicates that photopolymerization leads to the formation of clefts or pockets on the vesicle surface and to extensive surface inhomogeneity. Based on the experimental data, a computer simulation has been developed to help graphically visualize the photopolymerization process and to semi-quantitatively characterize the resulting surface inhomogeneity. As a first step in exploring the possibilities opened up by the discovery of clefts in the vesicle surface, the interaction between a photoexcitable proton transfer agent, 8-hydroxy-1,3,6 - pyrenetrisulfonate (POH), and vesicles has been studied. In unpolymerized vesicles POH loses its proton ejection capacity after several hours, whereas it remains active virtually indefinitely in polymerized vesicles. Polymerized vesicles thus allow selective accomodation of molecules into their surface clefts and permit communication of such molecules with the aqueous medium surrounding the vesicle. Possibilities for utilization of polymeric surfactant vesicles, and different synthetic strategies, are discussed in the light of these findings.

Reed, Wayne Frederick

374

Fluorescence spectroscopic analysis of surface and subsurface residual stress fields in alumina hip joints  

NASA Astrophysics Data System (ADS)

We aim to establish a confocal spectroscopic technique able to study the features of fluorescence spectra arising from native Cr3+ impurity in polycrystalline alumina (Al2O3as a biomaterial and to use their emission lines as microscopic probes for the characterization of residual stress fields stored in artificial hip prostheses during their implantation in vivo. As an application of the technique, we report for the first time concerning the evolution of microscopic (residual) stress fields stored on the surface and in the subsurface of N=7 retrieved Al2O3 hip joints after exposure in the human body from a few months to 19 yr. The micrometric diameter of the laser beam waist impinging on the joint surface (typically about 1 µm in lateral resolution) enables us to estimate the patterns and magnitude of residual stress with high spatial resolution, at least comparable with the grain size of the material. In addition, a selected confocal configuration for the optical probe enables minimization of the probe size along the in-depth direction. According to a statistical collection of data on the microscopic level for retrieved femoral heads in toto, a residual stress field arising from loading history in vivo during the lifetime of the Al2O3 femoral head can be revealed. Finally, an interpretation is given of microscopic wear mechanisms in Al2O3 artificial hip joints consistent with the observed evolution of surface residual stress fields on elapsed time in vivo.

Pezzotti, Giuseppe; Tateiwa, Toshiyuki; Zhu, Wenliang; Kumakura, Tsuyoshi; Yamamoto, Kengo

2006-03-01

375

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 NH and CO 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

376

Metal complexes of luteinizing hormone-releasing hormone (LHRH). Potentiometric and spectroscopic studies  

SciTech Connect

The results are reported of a potentiometric and spectroscopic study of the H+, Cu2+, and Ni2+ complexes of luteinizing hormone-releasing hormone (LHRH, HL) at 25 degrees C and an ionic strength 0.10 mol dm-3 (KNO3), since there is much evidence that the in vivo release of LHRH is influenced by the concentration of copper ions. With Cu2+ the hormone has been shown to behave similarly to the thyrotropin releasing factor, forming a very stable (CuH-1L) complex involving coordination of three nitrogen donors: the Nim atom of the imidazole side chain and the two amido-N atoms of the pyroglutamylhistidyl unit. With Ni2+, coordination proceeds differently to give four nitrogen coordination.

Gerega, K.; Kozlowski, H.; Masiukiewicz, E.; Pettit, L.D.; Pyburn, S.; Rzeszotarska, B.

1988-05-01

377

Molecular complexes of ketaconazole and oxatomide with p-chloranil: spectroscopic and spectrofluorimetric studies.  

PubMed

The molecular complexes of the donors ketaconazole (KTZ) and oxatomide (OXA) drugs with 2,3,5,6-tetrachloro-1,4-benzoquinone (p-chloranil, p-CHL) have been investigated spectroscopically (UV-vis, FT-IR and 1H NMR) and spectrofluorimetrically in different solvents and temperatures. The stoichiometry of the complexes was found to be 1:1. The data are discussed in terms of formation constant, molar extinction coefficient, oscillator strength, dipole moment, ionization potential, dissociation energy and thermodynamic parameters. The results indicated that the formation of molecular complex is spontaneous and endothermic. The fluorescence quenching studies indicated that the interaction of the donors is spontaneous and the fluorescence quenching increased with an increase in the intensity of complexation with the acceptor. PMID:21632281

Balraj, C; Ganesh, K; Elango, K P

2011-05-12

378

Spectroscopic studies on the interaction of fluorescein and safranine T in PC liposomes.  

PubMed

In this study, the fluorescence quenching of fluorescein by safranine T in liposome media had been investigated systematically by fluorescence spectroscopy, UV-vis absorption spectroscopy and fluorescence decay lifetime measurements. The spectroscopic data were analyzed using a Stern-Volmer equation to determine the quenching process. The experimental results showed that the intrinsic fluorescence of fluorescein was strongly quenched by safranine T, and that the quenching mechanism was considered as static quenching by forming a ground-complex. The Stern-Volmer quenching constant Ksv, and the bimolecular quenching constant Kq were estimated. The distances between the donor (fluorescein) and the acceptor (safranine T) were calculated according to the Förster non-radiation energy transfer theory. In addition, the partition coefficient of the safranine T (Kp) in the L-egg lecithin phosphatidylcholine liposomes was also calculated by utilizing the fluorescence quenching. PMID:23099157

Bozkurt, Ebru; Bayraktutan, Tu?ba; Acar, Murat; Toprak, Mahmut

2012-09-29

379

Spectroscopic studies on the interaction of fluorescein and safranine T in PC liposomes  

NASA Astrophysics Data System (ADS)

In this study, the fluorescence quenching of fluorescein by safranine T in liposome media had been investigated systematically by fluorescence spectroscopy, UV-vis absorption spectroscopy and fluorescence decay lifetime measurements. The spectroscopic data were analyzed using a Stern-Volmer equation to determine the quenching process. The experimental results showed that the intrinsic fluorescence of fluorescein was strongly quenched by safranine T, and that the quenching mechanism was considered as static quenching by forming a ground-complex. The Stern-Volmer quenching constant Ksv, and the bimolecular quenching constant Kq were estimated. The distances between the donor (fluorescein) and the acceptor (safranine T) were calculated according to the Förster non-radiation energy transfer theory. In addition, the partition coefficient of the safranine T (Kp) in the L-egg lecithin phosphatidylcholine liposomes was also calculated by utilizing the fluorescence quenching.

Bozkurt, Ebru; Bayraktutan, Tu?ba; Acar, Murat; Toprak, Mahmut

2013-01-01

380

Prompt ? spectroscopic studies of fragment nuclei in thermal neutron induced fission of 235U  

NASA Astrophysics Data System (ADS)

The prompt ?-? coincidence technique has been used to carry out the spectroscopic study of the level schemes and to derive the relative isotopic yield distributions of fission fragment nuclei employing the 235U(nth, f) reaction for the first time. From the coincidence rates of various Ba isotopes with 90Kr nucleus and of Sr isotopes with 138Xe nucleus, it has been found that either the 2n or 3n neutron evaporation channels dominate during the fission process. The average angular momenta for three complementary pairs have been estimated. The yrast and near-yrast level structures in several isotopes of six elements (Sr, Xe, Kr, Ba, Zr, and Te) have been deduced. The level schemes obtained are compared with earlier reported works, where different reactions or spontaneous fission (SF) data were used.

Mukhopadhyay, S.; Danu, L. S.; Biswas, D. C.; Goswami, A.; Prashanth, P. N.; Kinage, L. A.; Chatterjee, A.; Choudhury, R. K.

2012-06-01

381

A dielectric spectroscopic study of the disperse structure of asphaltene solutions at high pressures  

SciTech Connect

The disperse structure of oil asphaltenes in benzene and toluene solutions at different temperatures and concentrations were studied at pressures up to 1.0 GPa. The polarity of the asphaltene molecules allows the dielectric spectroscopic method to be used. A sharp increase in the relaxation time and the sizes of the asphaltene aggregates, calculated according to the Debye model near the phase transition point, were found in the benzene solution. The pressure value corresponding to crystallization is much higher in the toluene solution, and only the border region can be investigated. An explanation of the pressure dependences of the relaxation times are presented. The activation energies and the coefficients of isothermal compressibility are calculated.

Syunyaev, R.Z.; Sh. Abid, R. [Gubkin Oil and Gas Institute, Moscow (Russian Federation)

1994-03-01

382

Theoretical study of the electronic and spectroscopic properties of some Ru(II) anticancer complexes.  

PubMed

DFT method has been applied to study the thermodynamic and spectroscopic properties of three Ru-based complexes. Possible reasons for the reported experimental stability of complexes 1 and 2 with bidentate chelating ligands over complex 3 have been explained using computed properties. The results show that the trend in their thermodynamic, hyperpolarizabilities, magnetizabilities and the NMR isotropic shielding agree well with many of their experimental properties which give further detail explanation to the reported differences in their stability, hydrolysis and anticancer activities. We also found out that these complexes which were originally designed as anticancer agents have high hyperpolarizabilities which suggest that they can also act as good non-linear optical (NLO) materials. PMID:23348198

Adeniyi, Adebayo A; Ajibade, Peter A

2012-12-28

383

Spectroscopic and simulation studies of adsorption and removal of hydrocarbons using novel materials  

SciTech Connect

The authors report adsorption and spectroscopic measurements for mixtures involving low molecular weight hydrocarbons (methane, propane, isobutane) and carbon dioxide and also for pure methane; where possible, comparisons with molecular simulation are made. AlPO{sub 4}-5 and VPI-5 were found to selectively adsorb isobutane in isobutane/CO{sub 2} gas mixtures and propane in propane/methane gas mixtures, while little or no selectivity was observed for isobutane in isobutane/propane on AlPO{sub 4}-5. In-situ diffuse reflectance infrared spectroscopy has been used to study the adsorbate-adsorbent and adsorbate-adsorbate interactions of trace gases on VPI-5. This provided an insight into the extents of adsorption and strengths of the intermolecular adsorbate-adsorbent interactions.

Koh, C.A.; Nooney, R.I. [Univ. of London (United Kingdom); Maddox, M.; Gubbins, K.E. [Cornell Univ., Ithaca, NY (United States). School of Chemical Engineering

1995-12-01

384

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

NASA Astrophysics Data System (ADS)

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

Kurhekar, Anil Sudhakar; Apte, Prakash R.

2013-02-01

385

Laser Raman and ac impedance spectroscopic studies of PVA: NH4NO3 polymer electrolyte.  

PubMed

Ion conducting polymer electrolyte PVA:NH(4)NO(3) has been prepared by solution casting technique and characterized using XRD, Raman and ac impedance spectroscopic analyses. The amorphous nature of the polymer films has been confirmed by XRD and Raman spectroscopy. An insight into the deconvoluted Raman peaks of upsilon(1) vibration of NO(3)(-) anion for the polymer electrolyte reveals the dominancy of ion aggregates at higher NH(4)NO(3) concentration. From the ac impedance studies, the highest ion conductivity at 303 K has been found to be 7.5x10(-3)Scm(-1) for 80PVA:20NH(4)NO(3). The conductivity of the polymer electrolytes has been found to depend on the degree of dissociation of the salt in the host polymer matrix. The combination of the above-mentioned analyses has proven worth while and in fact necessary in order to achieve better understanding of these complex systems. PMID:19963433

Hema, M; Selvasekarapandian, S; Hirankumar, G; Sakunthala, A; Arunkumar, D; Nithya, H

2009-11-13

386

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

NASA Astrophysics Data System (ADS)

This work presents the spectroscopic characterization and reaction studies of a Fe III-complex (2) of a tetraamido macrocyclic ligand (1, 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[a,g]cyclotridecene-6,7,14,16-tetraone). 2 was characterized primarily by means of EPR. In agreement with the magnetic moment ( ?eff = 3.87 BM), EPR spectroscopy of 2 shows signals consistent with S = 3/2 intermediate-spin ferric-iron. Besides EPR, mass spectrometry, UV/vis spectroscopy and cyclic voltammetry were used to further characterize 2. 2 is soluble in water and activates hydrogen peroxide under ambient conditions. 2 catalytically bleaches dyes, pulp and paper effluents and oxidizes several amines to their corresponding N-oxides with high turnover number and good yields.

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

2010-10-01

387

Mössbauer spectroscopic study of iron phosphate catalysts used in selective oxidation  

NASA Astrophysics Data System (ADS)

Three iron phosphate compounds FePO4, Fe2P2O7 and Fe7(PO4)6 have been synthesized and studied as catalysts for the oxidative dehydrogenation of isobutyric acid to methacrylic acid. Mössbauer spectroscopic characterization of the solids before and after catalytic reaction has allowed us to show that the starting phases were transformed in the conditions of reaction and that a new phase was formed. This new phase is a mixed Fe3+ and Fe2+ phosphate with a Fe3+/Fe2+ ratio of 1.8±0.2 with Mössbauer parameters: ?1=0.47 ± 0.05, ?1=0.68± 0.02 mm.s-1 and ?2=1.20 ± 0.05, ?2=2.73±0.02 mm.s-1. This new phase appears to be elective for methacrylic acid formation.

Millet, J. M.; Virely, C.; Forissier, M.; Bussière, P.; Vedrine, J. C.

1989-03-01

388

Exploring the Spectroscopic Capabilities of SAFARI for studies of the Distant Universe  

NASA Astrophysics Data System (ADS)

Deep photometric surveys in the submm and FIR have identified a previously unknown population of distant, dusty galaxies that emit the bulk of their significant bolometric luminosity in the rest-frame IR. Determining the nature of these sources along with what powers their prodigious submm/FIR output is key to securing the place of this cosmologically significant population on the evolutionary pathway of galaxies. Deep MIR and FIR spectroscopy presents the best prospects for interrogating this distant and highly obscured population. In this paper we present he preliminary results of a quantitative study to determine how efficient SAFARI will be at making deep spectroscopic surveys in the MIR and FIR, and introduce a new SAFARI-specific diagnostic from the rest-frame MIR that can be used to differentiate between AGN and starbursts using lines that fall in the SAFARI waveband in objects at z > 0.4.

Isaak, Kate G.; Sturm, Eckhard; Elbaz, David; Spinoglio, Luigi; Gruppioni, Carlotta

2009-12-01

389

Study of the interaction of deoxynivalenol with human serum albumin by spectroscopic technique and molecular modelling.  

PubMed

The mechanism of interaction between deoxynivalenol (DON) and human serum albumin (HSA) was studied using spectroscopic methods including fluorescence spectra, UV-VIS, Fourier transform infrared (FT-IR) and circular dichroism (CD). The quenching mechanism was investigated in terms of the association constants, number of binding sites and basic thermodynamic parameters. The distance between the HSA donor and the acceptor DON was 2.80 nm as derived from fluorescence resonance energy transfer. The secondary structure compositions of free HSA and its DON complexes were estimated by the FT-IR spectra. Alteration of the secondary protein structure in the presence of DON was confirmed by UV-VIS and CD spectroscopy. Molecular modelling revealed that a DON-protein complex was stabilised by hydrophobic forces and hydrogen bonding. It was potentially useful for elucidating the toxigenicity of DON when combined with biomolecular function effect, transmembrane transport, toxicological testing and the other experiments. PMID:23205852

Li, Yuqin; Wang, Hao; Jia, Baoxiu; Liu, Caihong; Liu, Ke; Qi, Yongxiu; Hu, Zhide

2012-12-03

390

Structural and thermal stability analysis of Escherichia coli and Alicyclobacillus acidocaldarius thioredoxin revealed a molten globule-like state in thermal denaturation pathway of the proteins: an infrared spectroscopic study.  

PubMed Central

The structure of thioredoxin from Alicyclobacillus acidocaldarius (previously named Bacillus acidocaldarius ) (BacTrx) and from Escherichia coli ( E. coli Trx) was studied by Fourier-transform IR spectroscopy. Two mutants of BacTrx [Lys(18)-->Gly (K18G) and Arg(82)-->Glu (R82E)] were also analysed. The data revealed similar secondary structures in all proteins, but BacTrx and its mutants showed a more compact structure than E. coli Trx. In BacTrx and its mutants, the compactness was p(2)H-dependent. All proteins revealed the existence of a molten globule-like state. At p(2)H 5.8, the temperature at which this state was detected was higher in BacTrx and decreased in the different proteins in the following order: BacTrx>R82E>K18G> E. coli Trx. At neutral or basic p(2)H, the molten globule-like state was detected at the same temperature in both BacTrx and R82E, whereas it was found at the same temperature in all p(2)Hs tested for E. coli Trx. The thermal stability of the proteins was in the following order at all p(2)Hs tested: BacTrx>R82E>K18G> E. coli Trx, and was lower for each protein at p(2)H 8.4 than at neutral or acidic p(2)Hs. The formation of protein aggregates, brought about by thermal denaturation, were observed for BacTrx and K18G at all p(2)Hs tested, whereas they were present in R82E and E. coli Trx samples only at p(2)H 5.8. The results indicated that a single mutation might affect the structural properties of a protein, including its propensity to aggregate at high temperatures. The data also indicated a possible application of Fourier-transform IR spectroscopy for assessing molten globule-like states in small proteins.

Pedone, Emilia; Bartolucci, Simonetta; Rossi, Mose; Pierfederici, Francesco Maria; Scire, Andrea; Cacciamani, Tiziana; Tanfani, Fabio

2003-01-01

391

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

PubMed Central

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

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

2010-01-01

392

VCD spectroscopic and molecular dynamics analysis of the Trp-cage miniprotein TC5b.  

PubMed

TC5b is a 20 residue polypeptide notable for its compact tertiary structure, a rarity for a short peptide. This structure is due to the "Trp-cage" motif, an association of aromatic, Pro, and Gly residues. The structure of TC5b has been fully characterized by NMR and electronic circular dichroism (ECD) studies, but has never been studied with vibrational circular dichroism (VCD) spectroscopy, which may reveal finer structure. In this study, we examine the VCD spectra of TC5b to characterize the spectroscopic signature of the peptide and its comprising structural elements. TC5b exhibited a negative-positive-negative triplet which is associated with alpha-helical structure in deuterated solvents but also signs of a polyproline II (PPII) helix in the amide I' region. Detection of this element was complicated by the aforementioned triplet form, as well as by an upfrequency shift in PPII helical elements due to the use of the deuterated organic solvents DMSO-d(6) and TFE-d(1). Nevertheless, while ECD spectra showed only alpha-helical structure for TC5b, VCD spectroscopy revealed a more complex structure which was in agreement with NMR results. VCD spectroscopy also showed a rapid conformational change of the peptide at temperatures above 35 degrees C in D(2)O and in aqueous solvent with greater than 75% DMSO-d(6) content. Molecular dynamics (MD) simulations to investigate this latter effect of DMSO-d(6) on TC5b were conducted in DMSO and 50% (v/v) DMSO in H(2)O. In DMSO unfolding of the peptide was rapid while in 50% (v/v) DMSO in H(2)O the unfolding was more gradual. PMID:17326200

Copps, Jeffrey; Murphy, Richard F; Lovas, Sándor

2007-01-01

393

Evaluating spectroscopic and chromatographic techniques to resolve dissolved organic matter via end member mixing analysis.  

PubMed

Real-time or near real-time in-situ monitoring of dissolved organic matter (DOM) composition in natural waters and engineered treatment systems provides critical information to water quality scientists and engineers, particularly when the monitoring techniques can provide some information about the chemical nature of DOM. The efficacy of various indices derived from rapid, low-cost spectroscopic and chromatographic techniques to discriminate DOM composition was tested for samples prepared from well-defined mixtures of purified Aldrich humic acid (PAHA) and Suwannee River fulvic acid (SRFA). Sensitivities of the discrimination indices were examined by comparing (1) the differences between measured values and those predicted based from mass balance and the end member characteristics, and (2) the linear correlations between index values and mass ratios of the DOM mixtures. Size exclusion chromatography (SEC) results revealed that the weight-average molecular weight (MW(w)) may be a useful approach for tracking DOM mixing processes, although the number-average molecular weight (MW(n)) may be better for distinguishing different DOM compositions. Specific ultraviolet absorbance measured at 254 nm (SUVA(254)) performed better as a discrimination index than did two previously recommended absorbance ratios, both in terms of making better predictions of intermediate compositions and in exhibiting a more linear correlation with PAHA mass ratio. Several well-defined peaks in the derivative absorption spectra (301 and 314 nm for the first derivative, 217 nm for the third derivative, and 211 and 224 nm for the fourth derivative) also were found to be promising potential DOM discrimination indices. Finally, a fluorescence ratio based on humic- versus fulvic-like fluorescence proved to be a superior DOM discrimination index for the two DOM end members studied here. In general, this study illustrates the evaluation process that should be followed to develop rapid, low-cost discrimination indices to monitor DOM compositions based on end member mixing analyses. PMID:16307783

Hur, Jin; Williams, Miranda A; Schlautman, Mark A

2005-11-22

394

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

PubMed

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

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

2005-10-12

395

Molecular hydraulic properties of montmorillonite: a polarized fourier transform infrared spectroscopic study.  

PubMed

Understanding the rates at which fluid flows into clay interlayers at the molecular level is fundamental to designing an effective clay barrier system. In this work, molecular interactions at the Na-montmorillonite (MMT)-water interface, emphasizing the flow properties of the clay interlayer, have been studied at the molecular and nanoscale level using polarized Fourier transform infrared (FT-IR) spectroscopic and X-ray diffraction (XRD) techniques. Clay-water slurries were smeared on inert gold-coated metal substrates for FT-IR experiments and slurries were smeared on quartz plates for XRD experiments. By analyzing the O-H stretching and H-O-H bending vibrations in clay slurries, it was concluded that the molecular behavior of interlayer water is significantly different from the molecular behavior of bulk water. With increasing clay-water interaction time, it was also seen that the Si-O stretching bands of clay are being significantly altered by the water molecules in the interlayer. Using these spectroscopic techniques we have estimated the time required for water to flow into the clay interlayer. Further, by analyzing the particle size of the clay using atomic force microscopy (AFM) imaging, we were able to estimate the flow velocity of the water in the clay interlayer. This velocity is found to be 3.23 x 10(-9) cm/s. This flow velocity was found to be of the same order of magnitude as the hydraulic conductivity of smectite-type clay reported elsewhere. Also described in this work is the correct positioning of the Si-O out-of-plane vibration band of MMT at the two-layer saturation level in the interlayer. This band was only observed in p-polarized spectra at 1211 cm(-1). Thus, we attribute this band to the Si-O out-of-plane vibration band. PMID:19094388

Amarasinghe, Priyanthi M; Katti, Kalpana S; Katti, Dinesh R

2008-12-01

396

FTIR-based spectroscopic analysis in the identification of clinically aggressive prostate cancer  

Microsoft Academic Search

Fourier transform infrared (FTIR) spectroscopy is a vibrational spectroscopic technique that uses infrared radiation to vibrate molecular bonds within the sample that absorbs it. As different samples contain different molecular bonds or different configurations of molecular bonds, FTIR allows us to obtain chemical information on molecules within the sample. Fourier transform infrared microspectroscopy in conjunction with a principal component-discriminant function

M J Baker; E Gazi; M D Brown; J H Shanks; P Gardner; N W Clarke

2008-01-01

397

Photophysical properties of dipeptides containing substituted 3-(quinoxalin-6-yl) alanine. Spectroscopic studies and theoretical calculations.  

PubMed

The photophysical properties of excited states of two hybrid dipeptides [N-(3-(2,3-diphenylquinoxaline-6-ylo)alanylo) glycine], Pe-DPhQ, and [N-(3-(2,3 (pirydine-2-ylo) quinoxaline-6-ylo)alanylo) glycine], Pe-DPiQ, have been investigated by a combined solution-state study (absorption, emission) and quantum-mechanical (ab initio, DFT) calculations. The RHF and DFT B3LYP/6-31G (d,p) computations of the ground-state isomers of Pe-DPiQ dipeptide (open, half-closed, and closed) indicate that the most stable is the "open"-type structure with approximately equal (-44.43 degrees , -43.05 degrees ) dihedral angles describing rotation of the aromatic side rings with respect to the quinoxaline framework. This agrees with the literature findings that synthetic peptides are mostly unfolded. The experiments show that emission of Pe-DPiQ dipeptide is strongly temperature dependent, and at ambient and elevated temperatures the fluorescence is prevailing while the phosphorescence dominated emission spectra are observed at 77 K. On the basis of the decay curves that in the broad temperature range (rt-77 K) are biexponential (2 and 9 ns), it was concluded that at least its two major excited-state conformations may interconvert on the nanosecond time scale. The third component, of a small amplitude (10%) and a long time constant (25 ns), appears only in a new fluorescence band (570 nm) that grows up with the temperature increase. Analysis of the CIS/6-31G(d,p) results of the excited-state isomers of Pe-DPiQ supports the interpretation of experimental emission spectra and enables one to assign two excited-state conformations, demonstrating a tendency to keep one of their two side rings coplanar relative to the central quinoxaline plane, as Pe-DPiQ-I* (41.9 degrees , 6.3 degrees ) and Pe-DPiQ-II* (40.1 degrees , 4.5 degrees ) isomers contributing to the room temperature (403 nm) and 363 K (570 nm) fluorescence bands, respectively. The calculations also explain the electronic character of the corresponding S(1)<-->S(0) transitions and show that the state ordering of Pe-DPiQ resembles that of other diazines where the first singlet is of the npi* character while the S(2) and T(1) are the pipi* states. The reason for a strong phosphorescence is assigned to an effective spin-orbit coupling of appropriate singlet and triplet states that leads to ISC transitions and in result to population of the T(1) state and a phosphorescence from the T(1) state. From the present study, it was concluded that incorporation of quinoxaline moiety into the model peptides does not change the useful spectroscopic properties of the fluorophore and allows one to design its new analogues with improved activity and specificity. PMID:20712385

Wi?niewski, ?; Deperasi?ska, I; Staszewska, A; Stefanowicza, P; Berski, S; Lipkowski, P; Szewczuka, Z; Szemik-Hojniak, A

2010-09-01

398

AN IMPROVED SPECTROSCOPIC ANALYSIS OF DA WHITE DWARFS FROM THE SLOAN DIGITAL SKY SURVEY DATA RELEASE 4  

SciTech Connect

We present an improved spectroscopic and photometric analysis of hydrogen-line DA white dwarfs from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) based on model atmospheres that include improved Stark broadening profiles with non-ideal gas effects. We also perform a careful visual inspection of all spectroscopic fits with high signal-to-noise ratios (S/Ns > 12) and present improved atmospheric parameters (T{sub eff} and log g) for each white dwarf. Through a comparison of spectroscopic and photometric temperatures, we report the discovery of 35 DA+DB/DC double degenerate candidates and two helium-rich DA stars. We also determine that a cutoff at S/N = 15 optimizes the size and quality of the sample for computing the mean mass of DA white dwarfs, for which we report a value of 0.613 M{sub sun}. We compare our results to previous analyses of the SDSS DR4 and find a good agreement if we account for the shift produced by the improved Stark profiles. Finally, the properties of DA white dwarfs in the SDSS are weighed against those of the Villanova White Dwarf Catalog sample of Gianninas et al. We find systematically lower masses (by about 3% on average), a difference that we trace back to the data reduction procedure of the SDSS. We conclude that a better understanding of these differences will be important to determine the absolute temperature scale and mean mass of DA white dwarfs.

Tremblay, P.-E.; Bergeron, P.; Gianninas, A., E-mail: tremblay@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca, E-mail: gianninas@astro.umontreal.ca [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada)

2011-04-01

399

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

NASA Astrophysics Data System (ADS)

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

Paul, Puja; Suresh Kumar, Gopinatha

2013-04-01

400

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

PubMed

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

Paul, Puja; Suresh Kumar, Gopinatha

2013-02-01

401

Structural and spectroscopic studies on Er3+ doped boro-tellurite glasses  

NASA Astrophysics Data System (ADS)

Er3+ doped boro-tellurite glasses with the chemical composition (69-x)B2O3-xTeO2-15MgO-15K2O-1Er2O3 (where x=0, 10, 20, 30 and 40 wt%) have been prepared and their structural and spectroscopic behavior were studied and reported. The varying tellurium dioxide content in the host matrix that results, changes in structural and spectroscopic behavior around Er3+ ions are explored through XRD, FTIR, UV-VIS-NIR and luminescence measurements. The XRD pattern confirms the amorphous nature of the prepared glasses and the FTIR spectra explore the fundamental groups and the local structural units in the prepared boro-tellurite glasses. The bonding parameters (?¯ and ?) have been calculated from the observed band positions of the absorption spectra to claim the ionic/covalent nature of the prepared glasses. The Judd-Ofelt (JO) intensity parameters ?? (?=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from the absorption spectra and their results are studied and compared with reported literature. The variation in the JO parameters ?? (?=2, 4 and 6) with the change in chemical composition have been discussed in detail. The JO parameters have also been used to derive the important radiative properties like transition probability (A), branching ratio (?R) and peak stimulated emission cross-section (?PE) for the excited state transitions 2H9/2?4I15/2 and 2H11/2 and 4S3/2?4I15/2 of the Er3+ ions and the results were studied and reported. Using Davis and Mott theory, optical band gap energy (Eopt) values for the direct and indirect allowed transitions have been calculated and discussed along with the Urbach energy values for the prepared Er3+ doped boro-tellurite glasses in the present study. The optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar results.

Selvaraju, K.; Marimuthu, K.

2012-04-01

402

An atmospheric-pressure microplasma jet source for the optical emission spectroscopic analysis of liquid sample  

Microsoft Academic Search

A miniaturized atmospheric-pressure thermal plasma jet source has been developed as a sensitive detector of a portable liquid analysis system that can fulfil various requirements of `on-site' analysis. The plasma source design required for achieving higher power transfer efficiency to the plasma has been studied mainly so that it can be operated with a commercially available compact VHF transmitter. The

Takanori Ichiki; Toru Koidesawa; Yasuhiro Horiike

2003-01-01

403

Spectroscopic analysis of polymerization and exonuclease proofreading by a high-fidelity DNA polymerase during translesion DNA synthesis.  

PubMed

High fidelity DNA polymerases maintain genomic fidelity through a series of kinetic steps that include nucleotide binding, conformational changes, phosphoryl transfer, polymerase translocation, and nucleotide excision. Developing a comprehensive understanding of how these steps are coordinated during correct and pro-mutagenic DNA synthesis has been hindered due to lack of spectroscopic nucleotides that function as efficient polymerase substrates. This report describes the application of a non-natural nucleotide designated 5-naphthyl-indole-2'-deoxyribose triphosphate which behaves as a fluorogenic substrate to monitor nucleotide incorporation and excision during the replication of normal DNA versus two distinct DNA lesions (cyclobutane thymine dimer and an abasic site). Transient fluorescence and rapid-chemical quench experiments demonstrate that the rate constants for nucleotide incorporation vary as a function of DNA lesion. These differences indicate that the non-natural nucleotide can function as a spectroscopic probe to distinguish between normal versus translesion DNA synthesis. Studies using wild-type DNA polymerase reveal the presence of a fluorescence recovery phase that corresponds to the formation of a pre-excision complex that precedes hydrolytic excision of the non-natural nucleotide. Rate constants for the formation of this pre-excision complex are dependent upon the DNA lesion, and this suggests that the mechanism of exonuclease proofreading is regulated by the nature of the formed mispair. Finally, spectroscopic evidence confirms that exonuclease proofreading competes with polymerase translocation. Collectively, this work provides the first demonstration for a non-natural nucleotide that functions as a spectroscopic probe to study the coordinated efforts of polymerization and exonuclease proofreading during correct and translesion DNA synthesis. PMID:22959853

Devadoss, Babho; Lee, Irene; Berdis, Anthony J

2012-08-28

404

Electrochemical and spectroscopic studies of some less stable oxidation states of selected lanthanide and actinide elements  

SciTech Connect

The technique of simultaneous observation of electrochemical and spectroscopic properties at optically transparent electrodes (OTE's) has been applied to the generation and characterization of some less stable oxidation states of selected lanthanides and actinides (Ce, Pr, Sm, Eu, Tb, Yb, U, Np, Am, and Cm) in complexing and noncomplexing aqueous solutions. Electrodes used in the study included reticulated vitreous carbon (RVC) and metal screen OTE's and a new OTE made from porous metal foam. Cyclic voltammetry at microelectrodes was used in conjunction with spectroelectrochemistry for the study of redox couples. Formal reduction potential (E/sup 0/') values for M(III)/M(II) redox couples measured in 1M KCl at pH 6 are reported. E/sup 0/' values for the Pr(IV)/Pr(III) and Tb(IV)/Tb(III) couples measured in carbonate solutions are reported also. U(VI)/U(V)/U(IV) and U(IV)/U(III) redox couples were also studied in 1M KCl. /sup 237/Np, /sup 243/Am, and /sup 248/Cm were studied in containment gloved box facilities. (BLM)

Hobart, D.E.

1981-01-01

405

Spectroscopic ellipsometry study of hydrogenated amorphous silicon carbon alloy films deposited by plasma enhanced chemical vapor deposition  

Microsoft Academic Search

The optical properties of the hydrogenated amorphous silicon carbon alloy films, prepared by plasma enhanced chemical vapor deposition technique from silane and methane gas mixture diluted in helium, have been investigated using variable angle spectroscopic ellipsometry in the photon energy range from 0.73 to 4.59 eV. Tauc-Lorentz model has been employed for the analysis of the optical spectra and it

D. K. Basa; G. Abbate; G. Ambrosone; U. Coscia; A. Marino

2010-01-01

406

Mineralogical Characterization Studies on Unburnt Ceramic Product Made from Rock Residue Additives by Ft-Ir Spectroscopic Technique  

NASA Astrophysics Data System (ADS)

The usability of waste rock (rock residue) powder as an additive material in ceramic samples was investigated. Qualitative analysis was carried out to determine the major and minor constituent minerals present in ceramic bodies made from rock residue powder by using FT-IR spectroscopic technique. Further, the representative ceramic bodies are analyzed by FT-IR technique to yield more information about the functional groups and also to estimate the order or disorder of kaolinite structure.

Vijayaragavan, R.; Mullainathan, S.; Balachandramohan, M.; Krishnamoorthy, N.; Nithiyanantham, S.; Murugesan, S.; Vanathi, V.

2013-10-01

407

N-[4-(3-methyl-3-mesityl-cyclobutyl)-thiazol-2-yl]-succinamic acid: X-ray structure, spectroscopic characterization and quantum chemical computational studies  

NASA Astrophysics Data System (ADS)

N-[4-(3-methyl-3-mesityl-cyclobutyl)-thiazol-2-yl]-succinamic acid (CBTSA).Spectroscopic and structural characterization of CBTSA.HF and DFT electronic structure investigation of CBTSA.The conformational analysis of CBTSA.

?en, Fatih; Dinçer, Muharrem; Çukuroval?, Alaaddin; Y?lmaz, ?brahim

2013-08-01

408

Applications of Synchrotron Radiation and Optical Spectroscopic Techniques to the Study of Electrochemical Interfaces  

NASA Astrophysics Data System (ADS)

Electrochemical interfaces, especially structural changes and spectroscopic properties of adsorbed species on electrode surfaces induced by electrode potential have been examined by means of X-ray absorption fine structure and optical spectroscopic techniques. Potential modulation reflectance spectroscopy and wavelength modulation reflectance technique have been used to monitor the spectral properties of cobalt tetrasulfonated phthalocyanine (CoTsPc) and methylene (MB) blue irreversibly adsorbed on electrode surfaces. With a combination of cyclic voltammetry, linear relationship has been found between the relative reflectivity and the coverage of oxidized species of CoTsPc on the basal plane of highly oriented pyrolytic graphite (HOPG(bp)). Wavelength modulation study has shown that CoTsPc and MB on electrode surfaces exhibit almost the same spectral properties with those when they are in solution phase. Spectral changes accompanying the one-electron reduction of mu-oxo(bis) (iron meso -tetrakis(methoxyphenyl)porphyrin) (FeTMPP)_2 O irreversibly adsorbed on Black Pearl (BP) in aqueous electrolyte have been examined in situ through X-ray absorption fine structure. In the pH range 5-10.8, the average iron -to-porphinato nitrogen distance, d(Fe-N_ {rm p}) (2.08 +/- 0.01 A) for the ferric species was found to be very similar to that for crystalline (FeTMPP)_2O. At extreme pHs, d(Fe-N_{rm p} ) values smaller than those observed in the intermediate pH range, which strongly suggest an axially coordinated dihydroxy (at very high pH) and diaquo (at very low pH) complexes as the predominant species. In contrast, the corresponding ferrous counterpart displayed values for d(Fe-N_{rm p}) (2.04 +/- 0.01 A) consistent with the iron center placed in the plane of the ring over the whole pH region examined. The XAFS studies of Ni and 9:1 Ni/Fe and 9:1 Ni/Co composite hydroxide have shown that (i) Ni-O and Ni-Ni distances in Ni(OH)_2 system are larger than those in NiOOH produced by oxidation; (ii) iron and cobalt ions replace nickel ions in hydrous oxide lattice forming single phase; (iii) iron and cobalt do not undergo oxidation state changes upon oxidizing Ni(OH) _2 to NiOOH, but remain as 3+ state. The XAFS studies of FeS_2 and its Li ion intercalated species have shown that electrochemical insertion of Li ion brings about a marked decrease in the amplitude of the EXAFS and makes Fe-S distance longer. (Abstract shortened by UMI.).

Kim, Sunghyun